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11859498 | The following description of exemplary embodiments refer to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. DETAILED DESCRIPTION OF THE INVENTION Turbomachines comprise parts and components that rotates with respect to each other, interfacing regions kept at very different operating pressures. The use of efficient seals is thus of paramount importance to avoid leakages of the process fluids, performance losses and damages to the parts of the turbomachine. Labyrinth seals are a type of mechanical seal that provides a tortuous path to help prevent leakage and are often employed to seal rotating components of turbomachines. Embodiments described herein provide a labyrinth sealing device configured to seal (or that can seal) a circumferential gap between mutually rotatable turbomachine components. The device comprises two sealing elements: a first sealing element, which may be connected to the first turbomachine component, and a second sealing element. The second sealing element, in turn, has an inner part and an outer part. The inner part is provided with a plurality of projections extending towards the second machine component to define the teeth of a labyrinth seal. The outer part is connected to the first sealing element through an elastic element to allow the distance between the first sealing element and the second sealing element to vary depending on the fluid dynamic forces acting on the turbomachine components thus allowing greater efficiency and flexibility of use. As it can be appreciated by looking at the table ofFIG.1, the clearance gap between a labyrinth seal and a rotor is affected by several parameters. Among them, rotor speed (centrifugal force), rotor vibrations and temperature/pressure play a key role. A proper design would thus need to consider the following requirements for a seal:1. To be tolerant to unexpected vibrations and in off-design conditions;2. To have a positive gap during the no-pressure cases such as at 1stcritical speed crossing;3. To have the minimum gap during the factory acceptance test case;4. To have the minimum gap in the normal pressure case (site conditions). The sealing device according to embodiments herein allows to reach the operative gap with differential pressures less than 1 bar and keep it controlled until the maximum pressure. To such extent, elasticity is introduced in the component by less stiff material and a less stiff design.FIG.2shows, in an exemplified way, possible alternatives referenced with letters A to F3:A—A labyrinth seal with an elastic medium between the teeth and the housing working as shock absorber. The elastic medium shall be perfectly sealed with the housing and seal;B—A labyrinth seal with a plurality of springs. A ring spring-like design is possible, for example, by joining different components by welding or brazing or by additive manufacturing. The shape of the elastic system can be «V-shaped», «C-shaped», «S-shaped» or whatever shape able to introduce elasticity in the system;C—Like B with only one spring. The number of elastic elements shall be suitable with the desired stiffness and can vary accordingly;D—Like B with the addition of a channel connecting a high pressure zone (p2) to an intermediate chamber in order to control gap closure with the pressure. The intermediate chambers need to be sealed and isolated from each other;E—Like D with the possibility to connect the intermediate chamber of the seal with a given intermediate labyrinth gap at higher pressure (p2-Δp1);F—A labyrinth seal with elastic walls;F1—as F wherein the intermediate chamber can be pressurized with an intermediate pressure as in E;F2—as F wherein the intermediate chamber can be pressurized with the high pressure (p2) or low pressure (p1) by holes on one of the vertical walls. These holes can be properly shaped in order to introduce some elasticity in the wall;F3—single wall version to have more flexibility. The number of elastic elements, defining also the intermediate chambers, is a design parameter together with the pressure connection points. FIG.3shows a more complex configuration with two intermediate chambers respectively connected with high pressure p2and p2-Δp1. With reference to the embodiment shown in this figure, the seal1is a device comprising a first sealing element101connected to a first turbomachine component2(for example a stator) and a second sealing element201coupled with a second turbomachine component3(for example a rotor). The second sealing element201has an inner part301and an outer part401. The inner part301of the second sealing element201has a plurality of projections501extending towards the second machine component2to define the teeth of a labyrinth seal between the high pressure region and the low pressure region of the turbomachine indicated respectively with p2and p1. In this embodiment, the outer part401of the second sealing element201is coupled with the first sealing element101through three elastic elements601,601′,601″ defining two pressure chambers701,701′ to allow the distance between the first sealing element101and the second sealing element201to vary depending on the fluid dynamic forces acting on the turbomachine components. The pressure chambers701,701′ located between the first sealing element101and the second sealing element201are in fluid communication with the processing fluid of the turbomachine to derive a force acting on the outer part401of the second sealing element201in the direction of gap closure (as shown by the arrow inFIG.3) to automatically adapt the clearance d between the seal and the rotor to various operating conditions. The elastic elements and intermediate chambers can be in any number depending on design constraints and can assume any shape as those, for example, shown inFIG.2. That means that the elastic elements can be in the form of walls, springs or combination thereof with or without intermediate chambers to be accessed through holes in the walls and/or in the sealing elements to derive the most appropriate intermediate pressures for those embodiments requiring so. Reverting to the table ofFIG.1, it is to be noted that an optimum seal needs to satisfy the requirements of having large gap at 1stcritical speed, small gap at very low pressure and also at high pressure. This results in a flexible seal (to properly work at low pressure) but also in a rigid seal (to properly work at full pressure). These contrasting needs are balanced by the use of a mechanical stop801in order to contain deformation above a given pressure as in the embodiment shown inFIG.4. The mechanical stop locks the seal deformation to a given value as shown inFIG.5. In the graph of this figure, on X-axis there is the differential pressure DP acting on the second sealing element in the direction of gap closure, while on the Y-axis there is the deformation of the seal, i.e. the clearance gap between the seal and the rotor. The value at DP=0 is set by adjusting the initial gap of the stopper, the pendency of the curve is determined by the elasticity of the material according to the well-known Hook law, while the saturation for DP values greater than the locking pressure is due to the action of the stopper that provides a threshold to the deformation. The maximum allowable gap is thus controlled by the design of the mechanical stop while the locking pressure is controlled by the system stiffness (elastic constant) and by the initial gap in the internal locking system. In an advantageous configuration, the locking pressure can be controlled also by using proper pressures in the chambers by spilling fluid from the labyrinth seal at different longitudinal distance using one or more channels connected with the intermediate pressures as discussed above with reference toFIG.3. The values Δp1, Δp2, Δp3shown in this figure represent the pressure drops the processing fluid encounter while moving from the high pressure side (p2) to the low pressure side (p1) of the turbomachine. By acting on the pressure of the intermediate chamber(s), the locking state can be reached at different locking pressures thus providing a powerful fine-adjusting mechanism. In an embodiment, referred to inFIG.6toFIG.10, the second sealing element is an elastically deformable element hinged at the first sealing element, and the variable distance between the first sealing element and the second sealing element depends on the deformation of the second sealing element with respect to the first sealing element. The elastic element configured to allow the distance between the first sealing element and the second sealing element to vary depending on the fluid dynamic forces acting on the turbomachine components, is therefore distributed on almost the whole length of the seal. Referring now toFIG.8,FIG.9and toFIG.10, the sealing device1according to embodiments of the present disclosure is intended to create a seal of the circumferential gap between two relatively rotating components, namely, a fixed stator2and a rotating rotor3. The device may be implemented in any type of turbomachine in which a connection between a high pressure region and a low pressure region exists. For example, device1may be implemented in a centrifugal compressor, an expander, a turbine, a pump, etc. The device1includes at least one, but preferably a plurality of adjacent labyrinth seals201(also referenced herein as rotoric portions or second sealing elements), circumferentially spaced by radial cuts901, which are located in a non-contact position along the exterior surface of the rotor3. The plurality of grooves forming the teeth501of the labyrinth seals may be machined or, in a particularly advantageous configuration, grown through additive manufacturing such that portions of higher elevation (also referred as “teeth”) formed between and by the grooves have a profile consistent with any requirements of an application of the device. For example, the tooth profile may be squared, trapezoidal, triangular, or any other shape that may be beneficial to a particular application of the device. The labyrinth seals201are hinged at one extremity4to a statoric portion101(also referenced in the present disclosure as first sealing element) of the turbomachine to allow elastic deformation of the sealing device as best shown inFIG.6andFIG.7. The statoric portion101has circumferential notches5for receiving corresponding circumferential protrusions6of the labyrinth seals201, the circumferential notches5and the circumferential protrusions6having corresponding inclined abutment surfaces7,8limiting the excursion of the protrusions6in the notches5in the radial direction to form a first stopper801. A second stopper801′ may be provided in the form of inclined abutment surfaces in the statoric portion101opposite the hinged extremity4coupled with corresponding inclined portions of the labyrinth seals201to further limit the deformation of the device at high pressures as best seen inFIG.7. Each labyrinth seal201may have a circumferential slot9defining a channel putting into fluid communication the space between the statoric and the rotoric portions101,201of the seal1with the processing fluid of the turbomachine. Said slot9may advantageously extend circumferentially only on part of the circumferential extension of each labyrinth seal201to finely control the effect of the intermediate pressure on the deformation of the sealing device. The statoric part101and the rotoric part(s)201of the sealing device1may advantageously be of the same material, particularly a metallic material such as Aluminum, reinforced PEEK or the like as shown inFIG.8. Alternatively the statoric part101and the rotoric part(s)201of the sealing device may advantageously be of a different material as shown inFIG.9. In another embodiment, the statoric part101and the outer part301of the labyrinth seals are of the same material, while the teeth of the labyrinth seal501are of a different material as shown inFIG.10. The teeth may, for example, be of thermoplastic material while the remaining parts of the sealing elements may be of metallic material such as Aluminum, Steel, Ni-alloys or the like. Teeth are, for example, inserted into a metal cartridge and glued. In some embodiments, the teeth of the sealing device501may be made of an abradable material, or, alternatively, in some other embodiments, the teeth may have an abradable coating formed on a surface thereof disposed opposite and in sealing relation with the rotor. Bi-material seal solutions, composed, for example, by a cartridge in metal and teeth in thermoplastic, are particularly advantageous as they allow to keep the deformations controlled and the shaft protected from contact, particularly at high pressures, minimizing the volume of costly material. In a particularly advantageous configuration, the sealing elements or parts thereof are realized through additive manufacturing process. The term “additive manufacturing” references technologies that grow three-dimensional objects one layer at a time. Each successive layer bonds to the preceding layer of melted or partially melted material. It is possible to use different substances for layering material, including metal powder, thermoplastics, ceramics, composites, glass and even edibles like chocolate. Objects are digitally defined by computer-aided-design (CAD) software that is used to create .stl files that essentially “slice” the object into ultra-thin layers. This information guides the path of a nozzle or print head as it precisely deposits material upon the preceding layer. Or, a laser or electron beam selectively melts or partially melts in a bed of powdered material. As materials cool or are cured, they fuse together to form a three-dimensional object. Thanks to additive manufacturing technology, any geometry for the teeth in particular, and for any part of the sealing device in general, can be obtained thus allowing to optimize the design and contain the overall costs. The result is a compliant seal that is tolerant to rubbing and contacts and that closes the gap since at low pressures (like during ASME PTC10 Type II test). Tighter clearances can be obtained, in fact, already starting from differential pressures of 0.6 bar with a strong limitation at higher pressures to realize a very powerful device, particularly when pressures spilt from various labyrinth regions are used to finely control the locking pressure. Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments. | 15,246 |
11859499 | DETAILED DESCRIPTION According to the present invention this is achieved by the application of thin film physically vapor deposited (PVD) hard coatings on the blade surfaces that come into contact with abradable clearance control coatings as for example (CoNiCrAlY-hBN, NiCrAl-bentonite, NiCrAl-hBN, NiCrFeAl-hBN) during incursion rub events in the compressor section of a turbine engine. In other words, according to the present invention the PVD hard coatings applied to the blades and in particular to the blade tips do have the purpose to protect against the wear resulting from interaction of the blade tips with the abradable substrate. Surprisingly PVD coatings which are known from cutting tool applications may be advantageously used in this context and show excellent protection performance, in particular if coated on titanium alloy, stainless steel and/or nickel alloy blades which are used on low and high pressure compressor rotors and blisks in aero engines, and industrial gas turbine compressor rotors. In the following throughout this disclosure the expression “tipping” is used when referring to provide a coating at least on the tip and preferably as well in the periphery of the tip of the blade. In order to define the word “periphery” it is assumed that a point on the surface of the blade shall according to the present invention be considered as part of the periphery of the tip of the blade if this point is no more than 100 times the coating thickness distant from the outermost part of the mounted blade (seen from the rotation axis). Up to now, it is not known in the art to apply PVD coatings on blade tips for tipping purposes. Blades are commonly used without any form of tipping as (with respect to production) the most economical solution. In cases however where tipping is used, the known technology is limited in general to thicker hard coatings such as those deposited by thermal spray techniques such as Atmospheric Plasma Spray (APS) and High Velocity Oxygen Fuel (HVOF) thermal spray. Coatings applied by these techniques are in general 100 to 200 micrometers thick and suffer disadvantages such as:insufficient adhesion to blade tip material; APS and HVOF coatings are mechanically bonded to the surface to be coated.coating dimensions (thickness) and weight are too large, especially for thin blade tips used in high pressure aero compressors.preparation of material to be coated requires surface roughening e.g. by grit blasting, which can damage the mechanical integrity of blade components. In contrast, coatings deposited on the tips by PVD techniques are mostly metallurgically bonded to the substrate material and have very high adhesion strengths, require no surface pre-preparation techniques that could adversely damage the blade materials, are exceptionally hard, oxidation resistant. According the present invention, tip coatings deposited by PVD can be applied as very thin layers to blade tips e.g. 1-40 microns, preferably 5-25 microns thick, with the advantage of controlled intrinsic coating stresses and moderate surface roughnesses, while at the same time the PVD coatings exhibit a high density and wear resistance. Tipping the blades with PVD coatings according to the present invention means for example applying to the tip of a blade and/or the periphery of the tip a thin (e.g. 1-40 micron thick) hard (e.g. 1000-3500 HV intrinsic coating hardness) PVD coating such as for example titanium nitride (TiN), titanium aluminium nitride (TiAlN), titanium silicon nitride (TiSiN), titanium carbon nitride (TiCN), chromium nitride (CrN) or aluminium chromium nitride (AlCrN), or combinations of these. These are hard coatings which are typically used in the context of cutting tools. It was quite surprising when the inventors found that with these PVD coatings and in particular with the hard thin film PVD coatings as typically used in the field of cutting tools blade wear damage can be decreased and/or eliminated under a wide range of blade incursion conditions into the shroud. It was further surprising that the mentioned nitride based coatings do not suffer from premature oxidation, although it is known that these nitride based coatings have a significantly lower oxidation resistance at high temperatures than e.g. oxides or cubic boron nitride, as explained above. It is not fully clear why this is works, however one possible explanation could be that the conditions present in the blade-tip and abradable surface interaction are approximately similar to the conditions when a high speed cutting tool is working on a metal alloy workpiece. The invention will now be described in detail and with the help of examples. The inventors based their studies on a broad range of abradable materials. Although these are as well coated (for example on the housing) the build up of these materials will be named coated shrouds in order to clearly distinguish them from the PVD coatings. The tests have been based on the following shroud coating materials: 1. Ni 4Cr 4Al 21 Bentonite Product names: Durabrade 2313, Metco 314NS, Metco 312NS, Durabrade 2311 These are cermet powders consisting of a nickel chromium aluminum alloy fully encapsulating the stabilized bentonite core. Encapsulation is achieved using a chemical cladding process. This provides a robust, high quality, binder-free composite powder. The powders were designed to produce substrates with varied erosion resistance and abradability to suit the end application. Substrates are designed to rub against nickel-based alloys or steel hardware. 2. CoNiCrAlY-hBN-Polyester The CoNiCrAlY (cobalt-nickel-chromium-aluminum-yttrium) matrix within substrates of these materials provides improved oxidation and corrosion resistance compared to other nickel-chromium-based abradable materials. The boron nitride component provides solid lubrication, thereby improving abradability and reducing blade wear during rub incursions. The substrate porosity can vary from 35 to 60 vol. %; which is controlled through the amount of entrapped polyester in the coating. It is this controlled, web-like metallic structure that allows for excellent friability against titanium alloy, steel or superalloy components. These substrates can be used at service temperatures up to 750° C. (1380° F.); however, an increased susceptibility to oxidation can be expected above 650° C. (1200° F.). For use under extreme environmental conditions or when hard, erosion resistant coatings are required, hard tipped mating blades or knife edges are recommended. Coatings of Metco 2042 and Metco 2043 are readily cut by bare, untipped nickel alloys and stainless steel components at service temperatures up to 650° C. (1200° F.). For use against bare, untreated titanium components, Metco 2042 is recommended at service temperatures up to 550° C. (1020° F.). 3. NiCrFeAl-hBN Product names: Metco 301C-NS and Metco 301 NS i.e. Ni13Cr8Fe6.5BN3.5Al 2. Nickel chromium alloy/boron nitride thermal spray powders are cermet composites, consisting of a nickel-chrome alloy, hexagonal boron nitride, and aluminum, and are manufactured using mechanical cladding techniques. The powders were designed to produce substrates with varied erosion resistance and abradability to suit the end application. Powders are best applied using the combustion powder spray process using either hydrogen or acetylene as the fuel gas. 4. Aluminium Bronze Polyester Product names: Metco 604NS, Metco 605NS, Metco 610NS Metco 604NS, Metco 605NS and Metco 610NS are powder materials designed to produce abradable substrates for aerospace and industrial turbine clearance control applications operating in marine environments where corrosion from salt is a concern. The metal matrix of these powders is a pre-alloyed aluminum bronze material. A specially formulated polyester material is combined with the aluminum bronze matrix material to form a low-density substrate structure. In the case of Metco 604NS and 605NS, the polyester is blended with the metallic constituent. Metco 610NS is a composite material where the polyester constituent is cladded to the metallic constituent using a solid organic binder. With respect to NiCrAl-hBN-Polyester one can refer to the substrates as described in US patent application: WO 2011/094222 A1 (Dorfman, Wilson et. al). In order to demonstrate the technical effect of the invention, an evaluation program was performed in the frame of which the performance of TiAlN coatings deposited on blade tips using a Physical Vapor Deposition (PVD) process at Oerlikon Balzers was tested. Accordingly TiAl6V4 and Inconel 718 blades were TiAlN-tipped and incursion tested against specific Oerlikon Metco abradable substrates. TiAlN-tipped TiAl6V4 alloy blades were rub tested at 450° C. against:1) M2042 abradable substrates: standard and high hardness levels HR15Y 39 and 69 respectively, as well as2) M314NS abradable substrates: standard hardness level HR15Y 50 In addition TiAlN tipped IN718 alloy blades were rub tested at 750° C. against:1) M2043 abradable hardness HR15Y 672) M314 abradable hardness HR15Y 50 All abradable substrates were thermally sprayed at Oerlikon Metco location in Switzerland (OM-CH). A series of 16 incursion tests was performed on the Oerlikon Metco (OM) incursion test facility. The tests were conducted at velocities of 250 and 410 m/s while the incursion rates tested were either 5 or 500 μm/s. The incursion depth to be reached was 1.0 mm. Under the given tests conditions where bare titanium alloy blades normally undergo significant wear against Metco 2042 and Metco 2043 abradables (mostly at low blade tip velocity and high incursion rate). In contrast TiAlN tipping was found to produce improved rubbing performance with the result that no blade wear was observed i.e. 0% blade wear, which is measured as a percentage of the total incursion depth of the blade tip into the abradable coating shroud, nominally 1.0 mm. Some slightly negative blade wear values e.g. −1.0% were obtained which indicates slight transfer of shroud material to the blade tip, with no observed damage to the blade tip or tip coating. Metco 314NS also exhibited blade wear when rubbed using bare TiAl6V4 blades without tipping. However after tipping these blades with TiAlN the incursion tests showed improved rubbing performance with no blade wear. The program clearly showed that application of thin hard PVD coatings to tips of blades such as for example titanium alloy and nickel alloy blades tip a dramatic reduction in blade tip wear damage can be observed, showing improvement in cutting performance of specific abradable (clearance control) substrate materials sprayed to hardness values of up to at least 70HR15Y (post polymer burn out heat treated state). The second embodiment of the present invention relates to abradable coatings used for high pressure compressor clearance control applications such as for example air turbines, industrial gas turbines and turbochargers. Blade materials concerned are for example titanium alloys, stainless steel alloys and nickel based superalloys. State of the art abradable materials for these applications are commonly metallic alloy based with low thermal stability as they show low oxidation and/or sintering resistance. They are manufactured on purpose in a softer and more porous condition in order to mitigate against blade damage, where blades in most cases have no protective tipping. This results in abradables with low bulk hardness. The porous nature of the abradable coatings make them particularly susceptible to high temperature oxidation due to the larger exposed surface area of metal alloy. In addition, the required higher porosity weakens the coating tensile strength and lowers its erosion resistance. Especially if high temperature applications are in the focus, it is a disadvantage that those materials are in general not temperature resistant. According to state of the art there are thermally stable zirconia-based polyester ceramic thermal spray powders which are commonly used as a high temperature abradable coating for clearance control applications in the turbine section of aerospace and industrial gas turbine engines and where the blade alloys are commonly manufactured from nickel based superalloys. In addition, porous and temperature resistant nickel and cobalt alloy based coatings are also employed in the high pressure compressor region of aerospace and industrial gas turbine engines where blade alloys are manufactured from either titanium alloys, stainless steels or nickel based superalloys. However for most of the higher temperature sealing applications the respective blade tips have to be covered with cubic boron nitride abrasive particles which are applied using established electroplating and high temperature brazing techniques as bare titanium alloys as stainless steel alloys or nickel alloys show too much wear against these hard ceramic abradables. In addition and especially if titanium alloys are used there is the potential of a titanium fire if abraded against high hardness abradable coatings. The first embodiment above discloses hard thin film coatings applied to blade tips in order to protect against wear induced by abradables. Surprisingly the inventors in addition found that when bare blade tips are coated with hard, wear resistant thin film coatings, then even high temperature resistant shroud materials such as thermally sprayed porous zirconia oxide or other porous lower density ceramics such as magnesium aluminates (magnesium spinels) can be used as shroud materials without damaging the blade tips. This now therefore enables the use of thermally stable (high melting point, high oxidation resistant) ceramic or intermetallic based clearance control materials specifically in both low and high pressure compressor regions of aero turbines, industrial gas turbines and turbochargers. Current state of the art for high pressure compressor clearance control (abradable) applications are abradable coatings which are:lower in bulk hardness (softer) than ceramic abradables,more porous than ceramic abradables.commonly metallic alloy based with lower thermal stability (oxidation and sintering resistance) than ceramics They need to be manufactured in a softer and more porous condition in order to mitigate against blade damage, where blades in most cases have no protective tipping. On the other hand it is known to coat the tips of blades in order to eliminate blade damage (wear). Use of PVD thin film coatings such as TiAlN and AlCrN deposited on the tips of blades is used in turbomachinery. Where examples of blade materials are:titanium alloys e.g. TiAl6V4, Ti6242, gamma TiAl type (Ti-45Al-8Nb)stainless steel alloys e.g. 17-4 PH steelnickel based superalloys e.g. Inconel 718. The inventors now found that the thin film hard coatings are so efficient in their wear protection effect that harder abradable shroud materials with higher thermal stability (high melting point/sintering resistance, high oxidation resistance) such as thermally sprayed porous zirconia oxide coatings e.g. Metco 2460 (M2460) can be used with advantage. TiAlN coatings were deposited on blade tips (Inconel 718) using a Physical Vapor Deposition (PVD) process. Incursion tested against two different sets of Metco 2460NS abradable coatings were thermally sprayed. Two incursion tests were performed on an incursion test facility. A first test was run rubbing a TiAlN blade tip coating against a hard version of plasma sprayed M2460NS coatings while a second test was run using another set of M2460NS coatings plasma sprayed using a standard spray parameter. Both tests were conducted at:blade tip velocity of 410 m/sincursion rate of 50 μm/s.Shroud temperature of 1100° C.Incursion depths of 0.2 mm or 0.5 mm. M2460NS is a zirconia-based polyester ceramic thermal spray powder which, as mentioned above is commonly used as a high temperature abradable coating for clearance control applications in the turbine section of aerospace and industrial gas turbine engines where according to prior art cubic boron nitride is used a blade material. The following two variants of this coating were manufactured by thermal spraying and heat treated to burn out the polyester porosity former. High hardness M2460NS: Macro hardness was measured at an average of 59HR15N (polymer burned out condition). This M2460NS abradable coating sample was tested after polymer burnout (550° C./6 h) The test run using a blade tip velocity of 410 m/s and an incursion rate of 50 μm/s exhibited good rubbing performance associated with no blade wear. Standard hardness M2460NS coating: Macro hardness was measured at an average of 36HR15N (polymer burned out condition). This M2460NS abradable coating sample was tested after polymer burnout (550° C./6 h). The test run using a blade tip velocity of 410 m/s and an incursion rate of 50 μm/s exhibited good rubbing performance associated with no blade wear and superficial blade height increase (2.1% blade height increase as a percentage of incursion depth). Typical blade wear seen for un-tipped (uncoated) Inconel 718 blades when incursion tested against M2460 shrouds ranges between 70-100% wear as a percentage of total incursion depth. Typically zero blade wear is seen for state of the art cubic boron nitride tipped Inconel 718 blades when incursion tested against M2460 shrouds. Surprisingly the ranges seen for the TiAlN coated blade tips are similar to those as seen from state of the art cubic boron nitride tipped blades i.e. zero blade wear as a percentage of total incursion depth. Based on these results it is assumed that if the tips are coated with AlCrN the ranges are at least comparable if not better. Especially in the high temperature range AlCrN might be preferred. Probably this goes back to the increased temperature stability of this PVD coating. Surface roughness measurements were made of the post incursion tested (cut) shroud surfaces and compared to those cut using a commercially available standard blade tip (abrasive cubic boron nitride). The results (given below in tables 1 and 2) indicated that the PVD tipped blade produced a smoother, lower roughness surface finish. Such improvements are critical for aerospace clearance control applications in all sections (compressor and turbine) of aero turbomachinery. The table ofFIG.3shows M2460NS shroud roughness after incursion vs. inventive PVD tipped Blade. The table ofFIG.4shows M2460NS shroud roughness after incursion vs. cBN tipped Blade according to state of the art. Improvements observed through the use of TiAlN and/or AlCrN PVD coatings on blades:Reduction in blade wear to zero when compared to un-tipped blades where blade wear is typically high at 70-100% of total incursion depth.Equivalent blade wear (zero) to that observed for current state of the art cubic boron nitride tipped blades.Improved reduction in shroud surface roughness over that observed for current state of the art cubic boron nitride tipped blades.Lower cost, lower dimensions (coating thickness) and higher manufacturing robustness of PVD tipped blades over that observed for current state of the art cubic boron nitride tipped blades. In particular, the ease with which thinner blade tips, with complex tip geometries can be coated by PVD techniques provide a significant advantage over the state of the art.Due to the ease with which nickel super alloy and stainless steel blade materials can be shaped and coated using hard, thin film PVD coatings they now enable the use of porous ceramic based abradables for use in high pressure compressor section of turbomachinery, having significant performance advantages in:i) Oxidation resistanceii) Sintering resistanceiii) Corrosion resistanceover state of the art high pressure compressor abradables (metallic alloy based).Due to the ease with which other blade materials such as titanium alloys can be coated using hard, thin film PVD coatings, they now open up the opportunity for the use of porous ceramic based abradables for use in low pressure compressor section of turbomachinery, with significant advantages in:i) Corrosion resistanceii) Improved thermal expansion mismatch and residual stress compatibility over state of the art low pressure compressor abradables (commonly aluminium alloy based). The combination of hard thin film coated blade tips and thermally stable porous ceramic shrouds as abradables was disclosed as advantageous as compared to prior art. Preferably the hard thin film coating comprises compound materials such as Me1 Me2X, where Me1 is preferably an element of the group formed by Ti, Cr or Zr or a combination thereof and Me2 is preferably Al and/or Si and X is preferably an element of the group formed by N, 0 or 8 or a combination thereof. The one skilled in the art knows a number of methods to efficiently apply such coatings on blade tips, among which the physical vapor deposition such as cathodic arc deposition or sputtering is preferred. According to another aspect of the present invention a method for coating blades with hard thin film coatings is disclosed. This aspect not only relates to the tips of the blades and the protection of these tips against the abradable shrouds but as well to the protection of the blades against erosion particles such as for example dust impinging with high velocity and under multiple angles of incidence onto the surface of the blades. As already mentioned above, physical vapor deposition is one of the preferred methods to apply such thin film coatings onto the surface of the blades. Examples are cathodic arc evaporation as well as sputtering. Typically cathodic arc evaporation provides very dense and hard layers which is of advantage in the applications the present invention is concerned with. The density can be realized as the particles to be deposited are positively charged to a high degree. Applying a negative bias voltage to the substrates accelerates these ions to the surface to be coated. However the resulting coatings in general have a considerable surface roughness, due to the so called droplets which typically are produced during arc evaporation and which are deposited onto the surface and incorporated into the thin films. As already discussed above in the context of coating the tips, such roughness might be of disadvantage. Apart from this the surface roughness on the blade surface creates centers where erosion particles can attack and create centers of erosion which naturally weakens the protection against erosion. Surface roughness in addition disadvantageously affects the flow within the turbine in an accidental and difficult to control manner. There are techniques to mostly avoid the deposition and incorporation of such droplets into the thin film or on its surface during cathodic arc evaporation. For example one could use filtered arc where magnetic and/or electric fields are used to influence the flight of the charged particles to be deposited. As the droplets are not charged or as they are mainly macroscopic, to have to be considerably accelerated, the coating particles are separated from the droplets on their way to the substrates to be coated. Sputtering is the other preferred method to apply a thin film to a substrate based on physical vapor deposition. In the context of sputtering ionized particles of a so called working gas are accelerated onto the surface of a sputtering target. When these ions are impinging into the target surface particles of the target material are catapulted out. Acceleration of the ionized working gas particles is based on a negative voltage applied to the target. As the bombardment of the target with these particles heats it up, the energy density with which the target can be run in general is limited. Sputtered thin films show less surface roughness as compared to thin films deposited by cathodic arc evaporation as no droplets are formed during deposition. However in general the sputtered particles are not charged or the degree of ionization is at least very low. Therefore these particles may not be accelerated in direction to the surface to be coated once they left the surface of the material providing target. The inventors of the present invention now found a way and had the idea to use a special PVD coating method for coating the blades, such method leading to high density thin films without incorporating any droplets into the films. The respective method is based on sputtering, however the energy density, with which the sputtering process is run is dramatically increased as compared to conventional sputtering. Such an increase results in charged particles ejected from the target surface and therefore a negative bias can be applied to the substrates to be coated in order to accelerate the charged coating particles in direction to the substrate. Heating of the target can be avoided by periodically and with high frequency switching off the respective voltage at the target. This so called HIPIMS is, as mentioned a sputtering method but has the disadvantage that complicated power generators which provide well shaped and reproducible high power pulses in a high frequency are required. In the context of another sputtering method as developed by the applicant, the power is not switched off, but is just switched to a different target and/or a power dump. The applicant provides this method under the brand “53p”. A detailed description of one example of implementing the respective sputtering method can be found in patent application WO2013/060415A1. According to one aspect of the present invention it is possible to accelerate the coating particles to such a velocity that when they hit the surface they have a velocity which is in the same order of magnitude as the expected mean velocity of the dust particles to impinge onto the surface during use of the blade. Preferably the hard thin film coating is produced by HIPIMS, especially preferred by S3p and comprises compound materials such as Me1Me2X, where Me1 is preferably an element of the group formed by Ti, Cr or Zr or a combination thereof and Me2 is preferably Al and/or Si and X is preferably an element of the group formed by N, O or B or a combination thereof. All PVD coatings mentioned in the description above can be monolayer or multilayer coatings. They can be applied with an adhesion layer between turbine blade substrate, however preferably directly onto the substrate material itself. In case of multilayers interlayers for example metallic interlayers can be foreseen. It is as well possible to have one or more layers comprising a gradient in the material composition as a function of coating depth, preferred however are monolayers and especially preferred is an AlCrN monolayer. It is as well possible to coat the blade body surface with another coating as compared to the blade tips. One could for example coat all exposed surface parts of the blades with a coating to be used for the blade tips, which preferably can be an AlCrN monolayer. After this it is possible to mask the tips and to coat the other surface parts in addition with some softer thin film material for the dust particles to impinge on the surface. A turbine engine was disclosed with a turbine section comprising a casing and at least one turbine blade rotatably mounted within the casing wherein at least part of the inner surface of the casing is covered with shrouds as abradables to provide clearance control between the inner surface and the tip of the at least one blade and wherein the tip of the blade is coated with a hard PVD coating, characterized in that the shroud material at least comprises and preferably is a porous ceramic based material. The PVD coating can be a coating comprising compound materials such as Me1Me2X, where Me1 is preferably an element of the group formed by Ti, Cr or Zr or a combination thereof and Me2 is preferably Al and/or Si and X is preferably an element of the group formed by N, O or B or a combination thereof. The shroud material can at least comprise and preferably is a zirconia-based polyester ceramic material. A method for manufacturing a turbine engine according to the turbine engines as described above was disclosed, the method comprising the steps of:thermally spraying the shroud material to the inner surface of the casingPVD coating at least the tip of the blade to be used within the casing The step of PVD coating can be performed by high power impulse magnetron sputtering with power density pulses equal or above 5 W/cm2 and preferably equal or below 50 W/cm2, more preferably equal or below 40 W/cm2 and most preferably equal or below 30 W/cm2. The power can be provided by a DC power generator and the pulses are realized by switching the power form one material delivering sputtering target to another and/or to a dummy target. Surprisingly the PVD coating95produced by high power impulse magnetron sputtering further exhibits a uniform coating thickness distribution with a maximum deviation of about 10% from the mean coating thickness t, measured on the blade tip9. The high uniformity of coating thickness and properties also applies along the coated corner between blade tip9and the mantle surface91of the turbine blade, as well as around the turbine blade, as indicated inFIG.2. It turned out that the essentially droplet free coatings exhibit an extremely dense structure which reduce the possibility of coating failure during operation. This feature is assumed to be responsible for the high durability of the PVD coatings against the metallic or ceramic shroud materials, almost independent of their pore volume. Several variants of the inventive PVD coatings, such as Ti50Al50N, Ti40Al60N, Ti33Al67N, as well as Al50Cr50N, Al60Cr40N and Al70Cr30N have been deposited and achieved a similarly good coating thickness distribution. The best performance results have been achieved if the PVD coating95exhibit Me2 contents of 40 to 70 at. %, when calculating from Me2/(Me1+Me2) in Me1Me2X, thereby taking only to the metallic constituents of the coating into account. It was found that the inventive PVD coatings can be deposited as thin layers, e.g. 1-40 microns, preferably 5-25 microns thick. | 30,356 |
11859500 | Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present disclosure. DETAILED DESCRIPTION Reference will now be made in detail to present embodiments of the disclosure, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the disclosure. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations. Additionally, unless specifically identified otherwise, all embodiments described herein should be considered exemplary. As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. The terms “coupled,” “fixed,” “attached to,” and the like refer to both direct coupling, fixing, or attaching, as well as indirect coupling, fixing, or attaching through one or more intermediate components or features, unless otherwise specified herein. Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. For example, the approximating language may refer to being within a 1, 2, 4, 10, 15, or 20 percent margin. Here and throughout the specification and claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. Pressure values, and ranges thereof, are in absolute pressure measurement (psia) or equivalent. Values and ranges of pressure provided herein may be converted to ranges in gauge pressure, or other pressure units, or other units, measurements, or combinations thereof that correspond to the values and/or ranges disclosed herein. The term “overall power output” refers to a maximum rated power output of an engine. The term “operating envelope” refers to a cycle, mission, or set of maneuvers at which the engine may normally operate. In one embodiment, a landing-takeoff (LTO) cycle may define an operating envelope. The LTO cycle including one or more combinations of startup, idle, takeoff, cruise, and approach engine operating conditions may collectively define the operating envelope. In various embodiments, the cruise condition defines a majority of the operating envelope, such as to define a majority of an operating time or duration of the engine operation. In certain embodiments, the cruise condition is between approximately 55% and 75% of the operating envelope. Stated differently, the cruise condition may define approximately 55% to approximately 75% of the duration of engine operation from startup to shutdown following approach operating condition. In another embodiment, the cruise condition may define approximately 60% to approximately 70% of the duration of engine operation. The term “cruise operating condition” may further refer to mid-power engine operating condition. The term “takeoff operating condition” may refer to a full power condition and “idle operating condition” may refer to a low power condition, and “cruise operating condition” is a power or thrust condition therebetween. In some embodiments, the cruise condition corresponds to approximately 75% to approximately 90% of an overall power output of the engine. In still certain embodiments, the cruise condition corresponds to approximately 80% to 88% of the overall power output of the engine. A “third stream” as used herein means a non-primary air stream capable of increasing fluid energy to produce a minority of total propulsion system thrust. A pressure ratio of the third stream may be higher than that of the primary propulsion stream (e.g., a bypass or propeller driven propulsion stream). The thrust may be produced through a dedicated nozzle or through mixing of an airflow through the third stream with a primary propulsion stream or a core air stream, e.g., into a common nozzle. In certain exemplary embodiments an operating temperature of the airflow through the third stream may be less than a maximum compressor discharge temperature for the engine, and more specifically may be less than 350 degrees Fahrenheit (such as less than 300 degrees Fahrenheit, such as less than 250 degrees Fahrenheit, such as less than 200 degrees Fahrenheit, and at least as great as an ambient temperature). In certain exemplary embodiments these operating temperatures may facilitate heat transfer to or from the airflow through the third stream and a separate fluid stream. Further, in certain exemplary embodiments, the airflow through the third stream may contribute less than 50% of the total engine thrust (and at least, e.g., 2% of the total engine thrust) at a takeoff condition, or more particularly while operating at a rated takeoff power at sea level, static flight speed, 86 degree Fahrenheit ambient temperature operating conditions. Furthermore in certain exemplary embodiments, aspects of the airflow through the third stream (e.g., airstream, mixing, or exhaust properties), and thereby the aforementioned exemplary percent contribution to total thrust, may passively adjust during engine operation or be modified purposefully through use of engine control features (such as fuel flow, electric machine power, variable stators, variable inlet guide vanes, valves, variable exhaust geometry, or fluidic features) to adjust or optimize overall system performance across a broad range of potential operating conditions. The term “turbomachine” or “turbomachinery” refers to a machine including one or more compressors, a heat generating section (e.g., a combustion section), and one or more turbines that together generate a torque output. The term “gas turbine engine” refers to an engine having a turbomachine as all or a portion of its power source. Example gas turbine engines include turbofan engines, turboprop engines, turbojet engines, turboshaft engines, etc. The term “combustion section” refers to any heat addition system for a turbomachine. For example, the term combustion section may refer to a section including one or more of a deflagrative combustion assembly, a rotating detonation combustion assembly, a pulse detonation combustion assembly, or other appropriate heat addition assembly. In certain example embodiments, the combustion section may include an annular combustor, a can combustor, a cannular combustor, a trapped vortex combustor (TVC), or other appropriate combustion system, or combinations thereof. The terms “low” and “high”, or their respective comparative degrees (e.g., -er, where applicable), when used with a compressor, a turbine, a shaft, or spool components, etc. each refer to relative speeds within an engine unless otherwise specified. For example, a “low turbine” or “low speed turbine” defines a component configured to operate at a rotational speed, such as a maximum allowable rotational speed, lower than a “high turbine” or “high speed turbine” at the engine. The term “at,” as used herein to refer to a location of a first object relative to a second object (e.g., the first object located or positioned at the second object) refers to the first object being positioned wholly or partially within the second object, the first object contacting the second object, or the first object being positioned closest to the second object (relative to any other surrounding relevant components). One or more components of the turbomachine engine described herein below may be manufactured or formed using any suitable process, such as an additive manufacturing process, such as a 3-D printing process. The use of such a process may allow such component to be formed integrally, as a single monolithic component, or as any suitable number of sub-components. In particular, the additive manufacturing process may allow such component to be integrally formed and include a variety of features not possible when using prior manufacturing methods. For example, the additive manufacturing methods described herein may allow for the manufacture of passages, conduits, cavities, openings, casings, manifolds, double-walls, heat exchangers, or other components, or particular positionings and integrations of such components, having unique features, configurations, thicknesses, materials, densities, fluid passageways, headers, and mounting structures that may not have been possible or practical using prior manufacturing methods. Some of these features are described herein. Suitable additive manufacturing techniques in accordance with the present disclosure include, for example, Fused Deposition Modeling (FDM), Selective Laser Sintering (SLS), 3D printing such as by inkjets, laser jets, and binder jets, Stereolithography (SLA), Direct Selective Laser Sintering (DSLS), Electron Beam Sintering (EBS), Electron Beam Melting (EBM), Laser Engineered Net Shaping (LENS), Laser Net Shape Manufacturing (LNSM), Direct Metal Deposition (DMD), Digital Light Processing (DLP), Direct Selective Laser Melting (DSLM), Selective Laser Melting (SLM), Direct Metal Laser Melting (DMLM), and other known processes. Suitable powder materials for the manufacture of the structures provided herein as integral, unitary, structures include metallic alloy, polymer, or ceramic powders. Exemplary metallic powder materials are stainless steel alloys, cobalt-chrome, aluminum alloys, titanium alloys, nickel based superalloys, and cobalt based superalloys. In addition, suitable alloys may include those that have been engineered to have good oxidation resistance, known as “superalloys” which have acceptable strength at the elevated temperatures of operation in a gas turbine engine, e.g. Hastelloy, Inconel alloys (e.g., IN 738, IN 792, IN 939), Rene alloys (e.g., Rene N4, Rene N5, Rene 80, Rene 142, Rene 195), Haynes alloys, Mar M, CM 247, CM 247 LC, C263, 718, X-850, ECY 768, 282, X45, PWA 1483 and CMSX (e.g. CMSX-4) single crystal alloys. The manufactured objects of the present disclosure may be formed with one or more selected crystalline microstructures, such as directionally solidified (“DS”) or single-crystal (“SX”). Embodiments of a gas turbine engine including an improved clearance control system are provided. The engine reduces weight and tubes, manifolds, or conduits outside of an outer core casing or fan casing by reducing or eliminating air extracted from a fan bypass passage for cooling at a turbine section. Embodiments provided herein allow for engines without fan casings, such as open rotor engines or propfan engines, to have and operate improved clearance control, cooling systems, or air systems for turbine sections and/or bearing assemblies. It should be appreciated that while such embodiments may be applied to turbofan engines including nacelles and fan casings, embodiments provided herein allow for engines without nacelles, fan casings, or other structures surrounding the fan section to receive air for turbine section cooling, clearance control, or bearing assemblies. The improved gas turbine engine provided herein may additionally, or alternatively, allow for lower-pressure and/or lower-temperature air to be removed from the compressor section for cooling or clearance control at the turbine section and bearing assembly. Certain clearance control systems may generally utilize high-energy air (i.e., high-pressure and/or high-temperature air), such as from aft stages of a high pressure compressor, and mix with one or more other sources of air, such as from other compressor stages or from the fan air stream. Such high-energy air reduces engine efficiency, such as by removing energy from the thermodynamic and combustion process, or by requiring greater reduction in heat load before the air is appropriate for cooling or clearance control at the turbine section. Still further, certain clearance control systems may not be suitable for additionally providing air to a bearing assembly for cooling, buffer air, or other uses at the bearing assembly. Another aspect of the disclosure is directed to an improved turbine casing allowing for improved clearance control, cooling fluid distribution, reduced weight, and improved engine efficiency. Embodiments of an engine, casing, and manifold provided herein include integral, unitary structures such as may be formed by additive manufacturing processes that would not have heretofore been possible or practicable. Embodiments depicted and described herein allow for improved and advantageous positioning of thermal control rings for improved clearance control response, improved formation and positioning of openings, passages, and conduits to allow for more efficient heat transfer fluid utilization and movement, and reduced weight, such as via obviating flanges and sub-assemblies into integral components. Particular combinations of these features allow for improved heat transfer properties and reduced thermal gradients. Improved heat transfer properties particularly include a lower heat transfer coefficient at certain features, such as at the plurality of walls that form thermal control rings as provided herein. Such improvements may mitigate or eliminate undesired or excessive deformation, ovalization, bowing, or other changes in casing geometry that may adversely affect deflections or result in undesired contact to the turbine rotors. Embodiments provided herein include, e.g., an integral, unitary high speed turbine casing and turbine center frame or mid-turbine frame positioned downstream of the high speed turbine and upstream of a low- or intermediate-pressure turbine. Embodiments provided herein further include, e.g., an integral, unitary clearance control manifold configured to provide heat transfer fluid to thermal control rings. The integral, unitary structures may further allow for improved positioning of the thermal control rings relative to the turbine rotors, such as to provide improved clearance control across the turbine rotor assembly. As used herein, the term “integral, unitary” as used to describe a structure refers to the structure being formed integrally of a continuous material or group of materials with no seams, connections joints, or the like. The integral, unitary structures described herein may be formed through additive manufacturing to have the described structure, or alternatively through a casting process, etc. Referring now to the drawings,FIG.1is a schematic cross-sectional view of an exemplary gas turbine engine10herein referred to as “engine10” as may incorporate various embodiments of the present disclosure. Particular embodiments of the engine10may be configured as a turbofan, turboprop, turboshaft, or propfan gas turbine engine, or one or more gas turbine engines configured as hybrid-electric gas turbine engines, or other gas turbine engine configuration. As shown inFIG.1, the engine10has a longitudinal or axial centerline axis12that extends therethrough for reference purposes. In general, the engine10may include a turbomachine14disposed downstream from a fan section16. The engine10includes a compressor section21in serial flow arrangement with a turbine section27. The turbomachine14may generally include a substantially tubular outer casing18that defines an annular inlet20. The outer casing18may be formed from multiple casings. The outer casing18encases, in serial flow arrangement, the compressor section21, a combustion section26, and the turbine section27. In a particular embodiment, the compressor section21includes a booster or low speed compressor22and a high speed compressor24. In a still particular embodiment, the turbine section27includes a first turbine assembly or high speed turbine28and a second turbine assembly or low speed turbine30(e.g., including vanes116and rotor blades118). A jet exhaust nozzle section32is positioned downstream of the turbine section27. A high speed shaft or spool34drivingly connects the high speed turbine28to the high speed compressor24. A low speed shaft or spool36drivingly connects the low speed turbine30to the low speed compressor22. The low speed spool36may also be connected to a fan shaft or spool38of the fan section16. In particular embodiments, the low speed spool36may be connected directly to the fan spool38such as in a direct-drive configuration. In alternative configurations, as is depicted in phantom inFIG.1, the low speed spool36may be connected to the fan spool38via a gear assembly37, such as to configure the engine10as an indirect-drive or geared-drive configuration allowing for a higher or lower rotational speed of the fan spool38versus the low speed spool36. Such gear assemblies may be included between any suitable shafts/spools within engine10as desired or required. Although depicted and described as a two-spool engine including the high speed spool34separately rotatable from the low speed spool36, it should be appreciated that the engine10may be configured as a three-spool engine including the high speed spool34, the low speed spool36, and a third spool or intermediate speed spool positioned in serial flow arrangement between the high speed spool34and the low speed spool36. Accordingly, the compressor section21may include an intermediate speed compressor separately rotatable from the high speed compressor24and the low speed compressor22. Similarly, the turbine section27may include a third turbine assembly or an intermediate speed turbine separately rotatable from the high speed turbine28and the low speed turbine30. The intermediate speed compressor and the intermediate speed turbine may together be coupled to form an intermediate speed spool fluidly between the high speed spool and the low speed spool. It should further be appreciated that in certain embodiments the low speed turbine30or second turbine assembly described herein generally refers to a separately rotatable spool downstream of the high speed turbine or first turbine assembly. As such, the second turbine assembly may include an intermediate speed turbine or a low speed turbine positioned aft or downstream of the high speed turbine. As shown inFIG.1, the fan section16includes one or more axially-spaced stages of a plurality of fan blades40that are coupled to and that extend radially outwardly from the fan spool38. An annular fan casing or nacelle42circumferentially surrounds the fan section16and/or at least a portion of the turbomachine14. It should be appreciated that for the embodiment depicted the nacelle42is supported relative to the turbomachine14by a plurality of circumferentially-spaced outlet guide vanes44. A bypass airflow passage48is formed downstream of one or more stages of the plurality of fan blades40and around an outer portion of the turbomachine14. In a particular embodiment, such as depicted inFIG.1, the bypass airflow passage48is defined at a downstream section46of the nacelle42(downstream of the outlet guide vanes44) and between the nacelle42and the outer portion of the turbomachine14. However, in other embodiments, it should be appreciated that the low speed compressor22may form one or more stages of the fan section16, such as depicted inFIG.3. As such, the bypass airflow passage48may generally include any flowpath downstream of one or more stages of the plurality of fan blades40or the low speed compressor22and bypassing or surrounding at least a portion of the high speed compressor24, and having a flow of bypass air177therethrough provide thrust. Accordingly, certain embodiments of the engine10provided herein may be configured as a third stream or adaptive cycle engine having a plurality of bypass airflow passages48downstream of one or more stages of the plurality of fan blades and/or the low speed compressor22and upstream of at least a portion of the high speed compressor24, with one or more of which configured as a “third stream.” The engine10includes a computing system1210configured to perform operations. The computing system1210is communicatively coupled to the turbomachine14and/or a starter motor (not depicted) to adjust, modulate, maintain, change, or articulate any one or more control surfaces to generate the flows of air, one or more embodiments of the flow of heat transfer fluid, and/or a liquid and/or gaseous fuel in accordance with aspects of the present disclosure provided herein. The computing system1210can generally correspond to any suitable processor-based device, including one or more computing devices. Certain embodiments of the computing system1210include a full authority digital engine controller (FADEC), a digital engine controller (DEC), or other appropriate computing device configured to operate the engine10. The computing system1210may include one or more processors1212and one or more associated memory devices1214configured to perform a variety of computer-implemented functions, such as steps of the methods described herein. As used herein, the term “processor” refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit (ASIC), a Field Programmable Gate Array (FPGA), and other programmable circuits. Additionally, the memory1214can generally include memory element(s) including, but not limited to, computer readable medium (e.g., random access memory (RAM)), computer readable non-volatile medium (e.g., flash memory), a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disc (DVD), non-transitory computer-readable media, and/or other suitable memory elements or combinations thereof. The computing system1210may include control logic1216stored in the memory1214. The control logic1216may include computer-readable instructions that, when executed by the one or more processors1212, cause the one or more processors1212to perform operations, such as outlined in one or more steps of the method1000provided further below. In still various embodiments, the memory1214may store charts, tables, functions, look ups, schedules etc. corresponding to the flows, or rates, pressures, or temperatures associated with the flows of air, heat transfer fluid, or fuel provided herein. The instructions can be software written in any suitable programming language or can be implemented in hardware. Additionally, and/or alternatively, the instructions can be executed in logically and/or virtually separate threads on the processor(s). The computing system1210may also include a communications interface module1230. In various embodiments, the communications interface module1230can include associated electronic circuitry that is used to send and receive data. As such, the communications interface module1230of the computing system1210can be used to receive data from one or more control surfaces, sensors, measurement devices, or instrumentation, or calculations or measurements corresponding to one or more portions of the engine10provided herein, and may execute one or more steps of the method1000provided herein. The computing system(s)1210can also include a network interface used to communicate, for example, with the other components of engine10. The network interface can include any suitable components for interfacing with one or more network(s), including for example, transmitters, receivers, ports, controllers, antennas, and/or other suitable components. It should be appreciated that the communications interface module1230can be any combination of suitable wired and/or wireless communications interfaces and, thus, can be communicatively coupled to one or more components of the apparatus via a wired and/or wireless connection. As such, the computing system1210may obtain, determine, store, generate, transmit, or operate any one or more steps of the method described herein via a distributed network. For instance, the network can include a SATCOM network, ACARS network, ARINC network, SITA network, AVICOM network, a VHF network, a HF network, a Wi-Fi network, a WiMAX network, a gatelink network, etc. Referring now toFIG.2, an exemplary embodiment of an open rotor configuration of the engine10depicted and described with regard toFIG.1is provided. The embodiment of the engine10provided inFIG.2is configured substantially similarly as provided inFIG.1. However, inFIG.2, the open rotor configuration of the engine10does not have a fan casing or the nacelle42(depicted inFIG.1) surrounding the plurality of fan blades40. The bypass airflow passage48is formed downstream of the plurality of fan blades40, or particularly downstream of the outlet guide vanes44, and radially outward of the outer portion of the turbomachine14. Referring now toFIG.3, an exemplary embodiment of an open rotor configuration in accordance withFIG.2is provided. The embodiment provided inFIG.3further includes a plurality of bypass airflow passages48formed downstream of the plurality of fan blades40, such as described above. In the particular embodiment depicted, the engine10includes a first bypass airflow passage48A and a second bypass airflow passage48B. The second bypass airflow passage48B is extended from a location between the low speed compressor22and the high speed compressor24to an exhaust to atmosphere (although in other embodiments the second bypass airflow passage48B may extend to the first bypass airflow passage48A). An articulating vane or door structure43may be positioned at the second bypass airflow passage48B. The door structure43may include any appropriate type of actuatable wall, vane, door, or other structure configured to desirably alter a flow of air172received from a core gas flowpath70and allowed through the second bypass airflow passage48B, such as depicted schematically via arrows177. The second bypass airflow passage48B may be referred to as a third stream. AlthoughFIG.3depicts the engine10having a three-stream or adaptive cycle with an open rotor configuration, it should be appreciated that the adaptive cycle configuration may also include a nacelle surrounding the fan section, such as depicted and described with regard toFIG.1. In such a manner, it should further be appreciated that although certain advantages and benefits provided herein may provide benefits for turbofan engines having nacelles, embodiments and arrangements of the components provided herein may overcome issues or challenges that are particular to open rotor configurations. Referring now toFIGS.4-5, enlarged cross-sectioned views of an engine10configured in a similar manner as one or more of the exemplary engines10depicted inFIGS.1-3are provided.FIGS.4-5depict walled conduits, manifolds, tubes, or other structures forming flowpaths configured to extract or receive a flow of air, depicted schematically via arrows91, from the compressor section21and provide the flow of air91to the turbine section27. The flow of air91provided to the turbine section27may be utilized for cooling blades, vanes, shrouds, or other portions of the turbine section27. In certain embodiments, the turbine section27includes a turbine frame308positioned in serial flow arrangement between the first turbine assembly or the high speed turbine28and the second turbine assembly or low speed turbine30. In still particular embodiments, a bearing assembly200is included at the turbine frame308. Accordingly, the turbine frame308may provide a static mount or support structure at which the bearing assembly200is positioned to support rotation of one or more spools (e.g., low speed spool36or high speed spool34). The turbine frame308further includes any appropriate quantity of conduits, manifolds, or passages309, or other structures for allowing at least a portion of the flow of air91(e.g., depicted further below as flow of air193) to the bearing assembly200. The flow of air to the bearing assembly200may provide cooling or buffer air at the bearing assembly200, such as to attenuate vibrations from the spool or generate desired bearing or rotor clearances. In other embodiments, the flow of air91is provided to the gear assembly37positioned at the fan section16, to the compressor section21, to the turbine section27, or to the jet exhaust nozzle section32. The engine10includes a first conduit110extended in fluid communication from the compressor section21to the turbine section27. The first conduit110is configured to communicate the flow of air91from the compressor section21to a first location271at the turbine section27. The first conduit110forms a flow passage separate from the core gas flowpath70. In a particular embodiment, the first conduit110provides the flow of air91from the compressor section21to the turbine section27while bypassing the combustion section26. A first heat exchanger141is positioned in thermal communication with the flow of air91through the first conduit110. The first heat exchanger141is configured to receive heat or thermal energy from the flow of air91through the first conduit110. Accordingly, the first heat exchanger141is configured to cool the flow of air91through the first conduit110before the flow of air91is provided to the turbine section27. The first heat exchanger141is configured as any appropriate heat exchanger for extracting heat or thermal energy from the flow of air91and receiving or transmitting heat or thermal energy to a heat transfer fluid, depicted schematically via arrows221. Particular embodiments of the engine10may include a fluid system220configured to flow the heat transfer fluid221as a lubricant, a liquid and/or gaseous fuel, a hydraulic fluid, a supercritical fluid, a refrigerant, or an appropriately cooler air or inert gas. The fluid system220provides the heat transfer fluid221into thermal communication with the flow of air91via the first heat exchanger141. In a particular embodiment depicted inFIG.9(discussed in more detail below), the heat transfer fluid221is a liquid fuel provided to the combustion section26. However, it should be appreciated that the heat transfer fluid221may be provided and utilized in any appropriate way, including, but not limited to, as a lubricant for a bearing system, an anti-icing fluid, fuel, or actuation fluid. Referring still toFIGS.4-5, the engine10includes a second conduit120extended from the first conduit110downstream of the first heat exchanger141(relative to the flow of air91from the compressor section21to the turbine section27). The second conduit120is extended in fluid communication to a second location272at the turbine section27. A flow control device130is positioned at the second conduit120. The flow control device130is configured to selectively adjust, alter, modulate, or otherwise change an amount of the flow of air91from the first conduit110through the second conduit120. In various embodiments, the second conduit120includes an inlet portion121and an outlet portion122. The inlet portion121is fluidly coupled to the first conduit110and the flow control device130. The inlet portion121extends from the first conduit110to provide a portion of the flow of air91, depicted schematically via arrows192, to the flow control device130. The outlet portion122is fluidly coupled to the flow control device130and the second location272of the turbine section27. The outlet portion122extends from the flow control device130to provide at least a portion of the flow of air192to the second location272at the turbine section27. In such a manner, it will be appreciated that for the embodiment depicted, the flow control device130is positioned between the inlet and outlet portions121,122of the second conduit120. The flow control device130may be a valve or any appropriate device for regulating, directing, controlling, or otherwise modulating an amount of flow of fluid across a passage or flowpath. The flow control device130may include an actuated valve or an automatic valve driven by an electric energy source, a pneumatic energy source (e.g., air, or particularly, at least a portion of the flow of air91), or a fluid source (e.g., liquid and/or gaseous fuel, hydraulic fluid, lubricant, or combinations thereof). The flow control device130may include ball valves, shuttle valves, or other appropriate type of valve or flow regulating device in accordance with the embodiments depicted and described herein. Accordingly, the flow control device130is configured to modulate the amount of flow of fluid through the outlet portion122of the second conduit120, such as depicted schematically via arrows94. In a particular embodiment, the engine10includes a third conduit123extending from the flow control device130to a third location273at the turbine section27, in fluid communication with both the flow control device130and the third location273. The flow control device130may therefore be a three-way valve configured to selectively change the amount of the flow of air91from the first conduit110through the inlet portion121of the second conduit120to one or both of the third conduit123and the outlet portion122of the second conduit120. Accordingly, the flow control device130may be configured to modulate an amount of the flow of air192through the outlet portion122of the second conduit120, such as depicted schematically via arrows194, and furthermore modulate and egress of at least a portion of the flow of air192through the third conduit123, such as depicted schematically via arrows195. The third conduit123may form a bypass passage to further allow for selective adjustment, control, or modulation of the flows of air through the flow control device130. In a particular embodiment, the third conduit123allows for a portion of the air extracted from the first conduit110to bypass the outlet portion122of the second conduit120and egress to the third location273at the turbine section27. In certain embodiments, the third location273allows for bypassing a clearance control system275(described below) and allowing the flow of air195to enter the turbine section27at the core gas flowpath70downstream of the clearance control system275, or to mix with the flow of air193at the turbine frame308, or to vent to ambient (not depicted). Referring still toFIGS.4-5, as briefly noted above, the turbine section27includes the clearance control system275. Exemplary embodiments of improved clearance control systems are depicted inFIGS.8-16, including a casing300, manifold assemblies316, and thermal control rings314such as provided therein. However, it should be appreciated that the clearance control system275depicted inFIGS.4-5may include any appropriate structure or assembly for controlling, adjusting, or otherwise modulating a dimension between a rotor blade tip and a surrounding shroud or wall at the turbine section27, otherwise referred to as tip clearance. The clearance control system275may be an active clearance control (ACC) system configured to dynamically control tip clearance. Particularly, the ACC system may be configured to desirably modulate the tip clearance based on an engine operating condition via the flow of air94received from the second conduit120and provided to a surrounding shroud at the turbine section27. The volumetric or mass flow rate of the flow of air94is regulated or modulated by the flow control device130. Modulating the amount of the flow of air94to the clearance control system275allows the tip clearance to be desirably regulated across various engine operating conditions and associated changes in temperature at the turbine section27. As temperatures and rotor speeds change at the turbine section27across various engine operating conditions, the flow control device130modulates the amount of the flow of air94provided to clearance control system275to maintain or provide a desired tip clearance. With regard to a landing-takeoff cycle (LTO) of the engine10and an aircraft, engine operating conditions include startup, idle, takeoff, climb, cruise, approach, or reverse thrust. However, it should be appreciated that other engine operating conditions and cycles may be applicable. Referring still toFIGS.4-5, the second location272at the turbine section27is at the clearance control system275. Accordingly, the second conduit120, or particularly the outlet portion122of the second conduit120, is fluidly coupled to the turbine section27to provide the flow of air94to the clearance control system275such as described herein. In a particular embodiment, the clearance control system275is operably coupled to a first turbine assembly or the high speed turbine28at the turbine section27. Accordingly, the engine10is configured to receive the flow of air91from the compressor section21and provide the portion of the flow of air94(from the flow of air91) to the clearance control system275at the high speed turbine28via the second conduit120. In still particular embodiments, the first conduit110is fluidly coupled to the turbine frame308positioned between the first turbine assembly, or the high speed turbine28, and a second turbine assembly, or low speed turbine30. The turbine frame308may include a plurality of vanes310in circumferential arrangement and positioned between the turbines28,30. The first location271at the turbine section27is at the turbine frame308. Accordingly, in such embodiments, the first conduit110is configured to provide at least a portion of the flow of air91to the turbine frame308at the first location271. In a particular embodiment, schematic arrows193depict a portion of the flow of air at the first conduit110downstream of a juncture with the second conduit120. The flow of air193is provided to the turbine frame308via the first conduit110. In particular embodiments further depicted and described with regard toFIGS.8-16, the flow of air193may be provided to the casing300and through the plurality of vanes310at the turbine frame308, such as depicted schematically via arrows99. Referring toFIGS.4-5, the turbine frame308may include or form one or more passages309configured to provide fluid communication of the flow of air193to the bearing assembly200. The flow of air193may provide a buffer fluid for operation of the bearing assembly200. The buffer fluid may desirably control or attenuate vibrations, or allow or generate desired clearances or vibratory responses at the bearing assembly200or the rotors to which the bearing assembly is coupled. Referring now specifically toFIG.5, in a particular embodiment, the engine10includes a second heat exchanger142in thermal communication with a flow of air at the bypass airflow passage48. The second heat exchanger142may be configured as a surface heat exchanger configured to receive heat or thermal energy from the flow of air194downstream of the flow control device130at the second conduit120. The heat transfer fluid at the second heat exchanger142is a flow of air through the bypass airflow passage48of the engine10, such as depicted schematically via arrows177. The second heat exchanger142configured as a surface heat exchanger has a heat exchange surface at the bypass airflow passage48and is configured to place the flow of air194at the second conduit120in thermal communication with the flow of bypass air177at the bypass airflow passage48. In a particular embodiment, the second heat exchanger142is positioned at the outlet portion122of the second conduit120and upstream of the second location272at the turbine section27. Referring back generally to bothFIGS.4-5, in a particular embodiment, the first conduit110includes an inlet manifold111configured to receive the flow of air91from a circumferential compressor location211at the compressor section21. It should be appreciated that although the embodiments depicted inFIGS.4-5depict a single circumferential compressor location211, the inlet manifold may be configured to receive the flow of air91from a plurality of circumferential compressor locations211. Referring now toFIG.6, a perspective view of an embodiment of a portion of an engine10in accordance with one or more ofFIGS.1through3is provided. The embodiment provided inFIG.6may be configured substantially similarly as described in regard to the embodiments inFIGS.4-5. InFIG.6, the engine10may include a plurality of inlet manifolds111evenly-spaced or asymmetrically-spaced along the circumferential direction C around the compressor section21. In various embodiments, the plurality of inlet manifolds111includes two (2) or more inlet manifolds. In one embodiment, the plurality of inlet manifolds111includes three (3) inlet manifolds. In another embodiment, the plurality of inlet manifolds111includes four (4) inlet manifolds and up to 30 inlet manifolds111. InFIG.6, the first conduit110includes a collector115configured to receive the flow of air91from the inlet manifold111. In particular embodiments, the plurality of inlet manifolds111is fluidly coupled to a single collector115to provide a collected or unified flow of air91to the first heat exchanger141. The collector115may provide the flow of air91to the first heat exchanger141, such as described herein. In a still particular embodiment, the first conduit110includes an outlet manifold112configured to fluidly communicate the flow of air91from the first heat exchanger141to the turbine section27at the first turbine location271at the turbine section27. The engine10may include a plurality of outlet manifolds112evenly-spaced or asymmetrically-spaced along the circumferential direction C around the turbine section27. In various embodiments, the plurality of outlet manifolds112includes two (2) or more outlet manifolds. In one embodiment, the plurality of outlet manifolds112includes three (3) outlet manifolds. In another embodiment, the plurality of outlet manifolds112includes four (4) outlet manifolds and up to 30 outlet manifolds. In various embodiments, the second conduit120is extended in fluid communication from one or more of the plurality of outlet manifolds112of the first conduit110. The plurality of outlet manifolds112may accordingly extend to a plurality of first turbine locations271at different circumferential positions at the turbine section27. It should be appreciated that although the embodiments depicted inFIGS.4-5depict a single circumferential first turbine location271, the first turbine location271may include a plurality of circumferential first turbine locations271. Embodiments of the engine10provided inFIGS.4-5may include the first conduit110as a fixed area flowpath from the compressor section21to the turbine section27. Stated differently, the first conduit110may include various cross-sectional areas or convergent and divergent flowpaths. However, the first conduit110and the circumferential compressor location211may define fixed or non-articulatable flowpath areas. Such fixed area flowpath allows for a constant volumetric or mass flow rate of the flow of air91from the compressor section21through the first conduit110with respect to a corresponding engine operating condition. Stated differently, the fixed area flowpath allows for the first conduit110to receive a corresponding flow rate of the flow of air91relative to the particular engine operating condition. Accordingly, embodiments of the engine10provided herein allow for constant flows of air91in thermal communication with the flow of heat transfer fluid221at the first heat exchanger141. For instance, flow rates of the heat transfer fluid221, such as a fuel flow rate or lubricant flow rate, may be controlled via a schedule, table, graph, or curve indicative of the flow rate versus the engine operating condition. In one embodiment, the flow of air91at the first conduit110may generally be fixed as a ratio or proportion of the overall flow of air entering the core engine inlet20into the compressor section21. In another embodiment, the flow of air91at the first conduit110may generally be fixed as a ratio or proportion of the flow of air entering the high speed compressor24from the low speed compressor22. The engine10may particularly include a variable area flowpath at the second conduit120via the flow control device130. Accordingly, the engine10may allow a fixed flow of air193to the turbine frame308, such as for the bearing assembly200, and a variable flow of air194to the clearance control system275. The flow control device130may adjust, articulate, or otherwise modulate the flow of air194to the clearance control system275as a function of engine operating condition. Modulation of the flow of air194via the flow control device130may be a function of inlet air speed (into the turbomachine14via an inlet20), or inlet air pressure (e.g., corresponding to altitude of the engine10during operation or at one or more engine operating conditions described above), or inlet air temperature, or combinations thereof. Modulation of the flow of air194via the flow control device130may additionally, or alternatively, be a function tip clearance at the turbine section27, or a predetermined schedule corresponding to wear or deterioration at the turbine section27. Certain embodiments of the engine10include particular placements of the circumferential compressor location211at particular axial stages or other location at the compressor section21corresponding to particular pressure ranges of the flow of air91during operation of the engine10. In various embodiments, the circumferential compressor location211from which the flow of air91is received from the core gas flowpath70corresponds to a compressor location having an airflow therethrough at a pressure between approximately 20 pounds per square inch (psi) and approximately psi during an engine operating condition corresponding to between approximately 55% and approximately 75% of an operating envelope. In another embodiment, the circumferential compressor location211from which the flow of air91is received from the core gas flowpath70may corresponding to a compressor location having an airflow therethrough at a pressure between approximately 30 pounds per square inch (psi) and approximately 50 psi during the engine operating conditions such as described herein. Accordingly, embodiments of the engine10provided herein allow for the clearance control system275and the bearing assembly200to operate and receive air from the compressor section21. In certain embodiments, the engine10provided herein allows for the clearance control system275to receive the flow of91from the compressor section21rather than from the bypass airflow passage48. Furthermore, or alternatively, the engine10provided herein allows for the flow of air91to be received from upstream, forward, or lower-pressure stages of the compressor section21in contrast to other compressor bleed systems that may receive high energy air from downstream, aft, or higher-pressure stages of a compressor section. Certain of these other compressor bleed systems may further mix the higher-energy air with lower-energy (i.e., lower pressure, lower temperature, or both) corresponding to the bypass airflow passage. Still further, or alternatively, embodiments of the engine10provided herein allow for a constant flow of air91through the first conduit110to maintain purge and backflow margin at the turbine frame308and bearing assembly200. Referring now toFIGS.7A-7B, a flowchart outlining steps of the method1000for operating an engine is provided. The steps of the method1000may be stored as instructions and/or executed as operations by embodiments of the engine10and the computing system1210provided herein. Accordingly, the method1000may be a computer-implemented method in which one or more steps is stored as instructions at the memory1214at the computing system1210and/or executed by one or more processors1212at the computing system1210. The computing system1210may cause embodiments of the engine such as described herein with regard toFIGS.1-6to perform operations such as outlined in the flowchart inFIGS.7A-7Band described further herein with regard to method1000. Referring to the flowchart inFIGS.7A-7B, and in conjunction with any one or more embodiments depicted inFIGS.1-6, the method1000includes at1010initiating rotation of one or both of a high speed spool or a low speed spool to, e.g., generate compressed air for combustion within a combustion section of a core engine. In various embodiments, a motive force, such as a starter motor or turbine air starter (not shown), initiates rotation of one or both of the high speed spool34or the low speed spool36to generate an initial airflow through the core gas flowpath70into the combustion section26for mixing with a liquid and/or gaseous fuel before igniting to generate combustion gases. The method1000further includes at1020compressing a flow of air through the compressor section. During operation of the engine10, a flow of air171is received at the fan section16. A portion of the flow of air171enters the turbomachine14through the core engine inlet20, such as depicted schematically via arrows172. The flow of air172is pressurized across successive rows or stages of compressor blades at the compressor section21. Particularly, the low speed compressor22may include a low pressure compressor or booster relative to the high speed compressor24including a high pressure compressor. In certain embodiments, a portion of the flow of air172compressed by the low speed compressor22may be bled or re-routed from the core gas flowpath70, such as to control stall, surge, or operability at one or both of the compressors22,24. The high speed compressor24receives the flow of air172and further compresses the flow of air, such as depicted schematically via arrows173inFIGS.1-3. The successive stages of compressor blades energize the flow of air173, such as to increase the pressure and temperature of the flow of air173before entering the combustion section26, such as depicted via arrows174. The method1000includes at1030extracting a portion of the compressed flow of air from the compressor section, such as described above. The method1000at1030may particularly include extracting the portion of compressed flow of air into a first conduit and bypassing a combustion section, such as provided above with regard to the first conduit110. The method1000includes at1040flowing the extracted portion of the compressed flow of air through the first conduit (e.g., first conduit110) to a turbine section. In a particular embodiment, the first conduit bypasses the combustion section when flowing the extracted portion of compressed flow of air to the turbine section. With regard toFIGS.1-6, a portion of the flow of air at the compressor section21is bled or removed from the core gas flowpath70and provided to the first conduit110, such as depicted schematically via arrows91inFIGS.1-5. Particular embodiments depicted herein may receive the flow of air91from the compressed flow of air173,174from the high speed compressor24. In still other embodiments, the flow of air91may be received from the compressed flow of air172from the low speed compressor22. It should be appreciated that embodiments of the engine10provided herein advantageously receive relatively lower-pressure and lower-temperature flows of air from the compressor section21, and may further avoid structures, complexities, actuatable devices, valves, and associated weight and efficiency losses related to mixing high-pressure and high-temperature air with low-pressure and low-temperature air from the fan bypass airflow passage. It should furthermore be appreciated that, while particular operating conditions and operating envelopes are provided herein, the engine10and/or method1000provided herein allows for performing one or more steps at any engine operating condition, including up to 100% of an overall power output. However, particular advantages and benefits are provided herein with regard to operation of the engine at engine operating conditions defining a majority of an operating envelope. As such, methods and structures provided herein allow for improved efficiency and reduced fuel consumption. In various embodiments, the method1000at1030includes extracting the portion of the compressed flow of air when the compressed flow of air at the compressor section is between approximately 20 pounds per square inch (psi) and approximately 60 psi. In a particular embodiment, the method1000at1030includes extracting the portion of the compressed flow of air when the compressed flow of air at the compressor section is between approximately 30 psi and approximately 50 psi. In a particular embodiment, the method1000includes at1035receiving the portion of the compressed flow of air from the compressor section, in which the portion of the compressed flow of air is between approximately 20 psi and approximately 60 psi, or between approximately 30 psi and approximately 50 psi. In a still particular embodiment, the method1000at1030and/or1035is performed continuously or constantly relative to a discrete engine operating condition, such as to allow for a fixed flow of air relative to the discrete engine operating condition. In a still particular embodiment, the method1000includes at1028operating the engine at an engine condition corresponding to between approximately 55% and approximately 75% of an operating envelope, or between approximately 60% and approximately 70% of the operating envelope, such as described above. In certain embodiments, one or both steps of the method1000at1030and at1035is preceded by, or contemporaneous to, the method1000at1028. In still certain embodiments, the method1000includes at1029operating the engine between approximately 75% and approximately 90% of the overall power output (e.g., rated thrust) of the engine, such as described above. In a still particular embodiment, the method1000at1029includes operating the engine between approximately 80% and approximately 88% of the overall power output of the engine. In certain embodiments, one or more ranges provided herein may define a discrete engine operating condition at which the method1000at1030and/or1035is performed continuously or constantly. In still particular embodiments, the method1000includes performing the steps at1028and1029concurrently. The method1000may include at1050flowing, via a fluid system, a heat transfer fluid in thermal communication with the extracted portion of compressed flow of air, such as described above. In a particular embodiment, the fluid system220depicted inFIGS.4-5is a liquid and/or gaseous fuel system configured to provide a flow of liquid and/or gaseous fuel to the compressed flow of air174to generate combustion gases175. In such an embodiment, the fuel is the heat transfer fluid221in thermal communication with the flow of air91via the first heat exchanger141. The flow of fuel receives heat or thermal energy from the relatively hotter flow of air91, which may advantageously alter certain properties of the fuel, such as viscosity, density, or other property that may desirably affect combustion, fuel-air mixing, swirl, emissions generation, vibrations, or smoke and particulate generation. In certain embodiments, the method1000may further include flowing, via the fluid system, a plurality of heat transfer fluids in thermal communication with the extracted portion of compressed flow of air. In various embodiments, the method1000includes providing one or more flows of fuel, lubricant, hydraulic fluid, refrigerant, a supercritical fluid, or another flow of air at the heat transfer fluid in thermal communication with the extracted flow of air. The method1000may further include modulating the flow of the heat transfer fluid to control a temperature of the extracted flow of air (e.g., flow of air91). Modulating the flow of heat transfer fluid may include adjusting a mass or volumetric flow rate, pressure, or temperature of the heat transfer fluid provided in thermal communication with the extracted flow of air. As provided above, the flow of liquid and/or gaseous fuel is mixed with the compressed air from the compressor section and ignited to form combustion gases175. The combustion gases175flow from the combustion section26to the turbine section27, and particularly to the high speed turbine28and the low speed turbine30. As the combustion gases175expand at the turbine section27, energy is released to drive rotation of the respective turbines28,30, which drives their respective spools34,36, compressors22,24, and fan blades40. It should be appreciated that the combustion gases175release variable amounts of heat at the turbine section27based on the engine operating condition. Accordingly, heat release and turbine rotor speed may alter the tip clearance between turbine rotor blade tips and surrounding shrouds, such as further described below. It should be appreciated that improved aerodynamic and operating efficiencies are generally achieved by minimizing tip clearances. Accordingly, clearance control systems are utilized to modulate the tip clearance based on engine operating condition to improve engine efficiency and performance. The method1000may further include at1060selectively flowing a portion of the flow of air through a second conduit (e.g., second conduit120) extended from the first conduit (e.g., first conduit110) downstream of the heat exchanger (e.g., first heat exchanger141). In a particular embodiment, the method1000includes at1062varying or modulating, via a flow control device (e.g., flow control device130) at the second conduit extended from the first conduit, the portion of the flow of air extracted to the second conduit (e.g., second conduit120) from the first conduit (e.g., first conduit110) downstream of the heat exchanger (e.g., first heat exchanger141). In a still particular embodiment, the method1000includes at1063modulating, via the flow control device, a second portion of the flow of air extracted from the first conduit to the third conduit extended from the flow control device, such as depicted inFIGS.4-5via arrows195. In a still particular embodiment, the method1000at1060is executed contemporaneously with the method1000at one or more of steps1028,1030, or1035. Accordingly, the method1000may allow for continuous, constant, or fixed flow of air from the compressor section through the first conduit, while modulating or varying the flow of air through the second conduit. In particular embodiments, the method1000allows for continuous, constant, of fixed flow of air from the compressor section through the first conduit and to the turbine section, or particularly the bearing assembly, while modulating or varying the flow of air through the second conduit to a clearance control system. As such, modulating the flow of air through the second conduit allows for a variable flow of air through to a clearance control system (e.g., clearance control system275) independent of whether the operating condition of the engine is steady-state (e.g., non-transient or non-varying) or transient (e.g., changing). The method1000may further include at1070selectively varying, altering, or modulating a tip clearance at a clearance control system based on the flow of air received from the second conduit via step1060and/or1062. It should be appreciated that the method1000provided herein may further provide for a method for operating a clearance control system and bearing assembly. Such methods may allow for variable flow rate, temperature, pressure, or other physical property of the flow of air through the second conduit to the clearance control system, while allowing for substantially constant or continuous flows of air through the first conduit relative to an engine operating condition. Although not depicted inFIGS.7A-7B, the method1000may further include generating a flow of bypass air through a bypass airflow passage. A portion of the flow of air171passes across the plurality of fan blades40and bypasses the turbomachine14, such as depicted via arrows176inFIGS.1-3. The flow of air176that enters the bypass airflow passage48, depicted schematically via arrows177, is large in volume or mass and cold relative to the flow of air pressurized by the compressor section21within the turbomachine14.FIG.5, which may be applied to the embodiments of the engine10in any ofFIGS.1-3, particularly depicts the relatively cold flow of bypass air177in thermal communication with the flow of air194via the second heat exchanger142. Accordingly, the method1000may further include at1064thermally communicating, via the second heat exchanger, the flow of bypass air with the portion of the flow of air extracted to the second conduit. The embodiment of the engine10depicted and described with regard toFIG.5may allow for increased magnitudes of heat transfer from the flow of air194, such as via the flow of bypass air177at the bypass airflow passage48. Furthermore, the embodiment depicted inFIG.5, when applied to an open rotor configuration such as depicted inFIG.2, may overcome challenges associated with removing nacelles and passages, tubes, or conduits that may route through nacelles to provide air for heat exchangers, clearance control systems, and/or bearing assemblies. Accordingly, the method1000, when applied to an open rotor configuration such as described herein, may provide for a method for operating an open rotor engine, or particularly, a method for operating a clearance control system for an open rotor engine, or more particularly, a method for operating a clearance control system and bearing assembly for an open rotor engine. Referring now toFIG.8, an enlarged cross sectioned view is provided of a turbine section portion of a turbomachine14in accordance with one or more ofFIGS.1-3, as may incorporate various embodiments of the present disclosure. As shown inFIG.8, a first turbine assembly is formed by the high speed turbine28. A first stage50of the first turbine assembly includes a plurality of first turbine rotor blades58extended within the core gas flowpath70, and further includes an annular array of stator vanes54(only one shown) axially spaced from an annular array of turbine rotor blades58(only one shown) at the high speed turbine28. In a particular embodiment, the high speed turbine28further includes a last stage60which includes an annular array of stator vanes64(only one shown) axially spaced from an annular array of turbine rotor blades68(only one shown). The turbine rotor blades58,68extend radially outwardly from and are coupled to the high speed spool34(FIG.1,FIG.2). The stator vanes54,64and the turbine rotor blades58,68at least partially define the core gas flowpath70for routing combustion gases from the combustion section26(FIG.1,FIG.2) through the high speed turbine28. As further shown inFIG.8, the high speed turbine28may include one or more shroud assemblies, each of which forms an annular ring about an annular array of rotor blades. For example, a shroud assembly72may form an annular ring around the annular array of rotor blades58of the first stage50and the annular array of turbine rotor blades68of the last stage60. In general, the shroud assembly72is radially spaced from blade tips76,78of each of the rotor blades58,68. A radial or clearance gap CL is defined between the blade tips76,78and respective inner surfaces of the shroud segments77. The shroud assembly72generally reduces leakage from the core gas flowpath70. The shroud assembly72can include a plurality of walls forming thermal control rings314that assist in controlling thermal growth of the shroud thereby controlling the radial deflection or clearance gap CL. Thermal growth in the shroud assemblies is actively controlled with the clearance control system275. The clearance control system275is used to minimize radial blade tip clearance CL between the outer blade tip and the shroud, particularly during cruise operation of the engine, such as described herein. Downstream along the core gas flowpath70, or aft of the high speed turbine28, is a second turbine assembly formed by the low speed turbine30. As previously described herein, the second turbine assembly is rotatably separate from the first turbine assembly, such as described in regard to the high speed turbine28and the low speed turbine30above with reference toFIG.1. The casing300surrounds the high speed turbine28. The casing300includes a plurality of vanes310extended through the core gas flowpath70aft of the first turbine assembly formed by the high speed turbine28and forward of the second turbine assembly formed by the low speed turbine30. The shroud assembly72is coupled to the casing300at an outer casing wall312. The outer casing wall312is an annular wall surrounding the shroud assembly72and extended along a circumferential direction C relative to the centerline axis12(FIGS.1-3). The outer casing wall312is extended along an axial direction A forward of the rotor blades58of the first stage50of the high speed turbine28(also referred to as the first stage of rotor blades58) and aft of the rotor blades68of the second or last stage60of the high speed turbine28(also referred to as the second stage of rotor blades68). The plurality of vanes310is extended from the outer casing wall312. The plurality of vanes310is extended into the core gas flowpath70, In certain embodiments further described herein, one or more of the plurality of vanes310may be hollow or include conduits or passages allowing for fluid flow within the vane. The outer casing wall312of the casing300is extended along the axial direction A from a downstream end or trailing edge of the aft-most stage of the rotor blades68to at least an upstream end or leading edge of the plurality of vanes310, such as depicted at dimension B inFIG.8. It should be appreciated that conventional turbine casings include separable or joined flanges, such as bolted flanges or welded flanges, between a high speed turbine casing and a downstream casing, such as an inter-turbine frame, mid-turbine frame, intermediate speed turbine casing, or low speed turbine casing. Embodiments of the casing300provided herein, include unitary, integral structures, such as formed by one or more additive manufacturing processes. Embodiments provided herein further form integral, continuous, compliant structures, allowing for the unitary, integral extension of the casing300such as provided herein, or further including one or more features integrally formed to the casing300such as provided herein. A plurality of walls forming thermal control rings314is extended along the circumferential direction C and extended outward along a radial direction R from the outer casing wall312. In various embodiments, the thermal control rings314include forward thermal control rings3141positioned outward along the radial direction R from the first stage of rotor blades58, or particularly from the blade tips76of the rotor blades58, of the high speed turbine28. In certain embodiments, such as depicted inFIG.8, the forward thermal control rings3141are positioned in alignment along the axial direction A to the first stage of rotor blades58(overlapping axial positions). In another particular embodiment, the thermal control rings314include aft thermal control rings3142positioned outward along the radial direction R from the last stage60of rotor blades68, or particularly from the blade tips78of the rotor blades68, of the high speed turbine28. In certain embodiments, such as depicted inFIG.8, the aft thermal control rings3142are positioned in alignment along the axial direction A to the last stage60of rotor blades68of the high speed turbine28(overlapping axial positions). The forward and aft thermal control rings3141and3142are provided to more effectively control blade tip clearance CL (shown inFIG.8) with a minimal amount of time lag and thermal control airflow (cooling or heating depending on operating conditions). The forward and aft thermal control rings3141and3142are formed with the outer casing wall312as an integral, singular, unitary structure of the casing300. The thermal control rings314provide thermal control mass to more effectively move the shroud segments77along the radial direction R to adjust the blade tip clearances CL. Such clearance control may provide for lower operational specific fuel consumption (SFC). The integral, unitary structure of the thermal control rings314and the outer casing wall312, with the outer casing wall particularly extended aft of the second or last stage of the rotor blades68of the high speed turbine28, may allow for improved clearance control, improved thermal control, and improved cooling flow. The structures provided herein allow for the thermal control rings314to be positioned radially outward of and in axial alignment with each stage of the high speed turbine rotor, such as to improve clearance control at each respective stage. The structures provided herein further allow for obviating flanges between the high speed turbine and an intermediate turbine frame between the high speed turbine and a downstream low speed turbine (or intermediate speed turbine, such as described herein). Embodiments of the integral casing provided herein are generally produced by one or more additive manufacturing processes such as described above. Although additive manufacturing may generally be applied to form various structures or integrate various components, it should be appreciated that combinations of integrated structures provided herein may overcome issues associated with integrating structures while providing unexpected benefits. In one instance, axially-extended casings may generally be susceptible to thermal distortion that may ovalize the core flowpath, which may adversely affect rotor operation as the rotors may rub within a non-concentric flowpath. As such, simple integration of relatively hot casings surrounding the high speed turbine with the relatively cooler casing surrounding downstream vanes proximate to the low speed turbine may adversely affect overall engine operation. In another instance, such large, axially-extended masses may require additional cooling flow, which results in increased fuel consumption and overall losses in engine performance. Embodiments of the engine provided herein overcome such issues at least in part by the positioning of the thermal control rings in axial alignment and radially outward of the respective stages of the high speed turbine blades. Removing flanges between a casing surrounding the high speed turbine rotors and a vane casing or frame downstream of the high speed turbine allows for the thermal control rings to be advantageously positioned as disclosed herein. Other embodiments of the engine provided herein overcome such issues at least in part by improved cooling flow structures, passages, and conduits. In various embodiments, a manifold assembly316surrounds the thermal control rings314along the circumferential direction C and the axial direction A. The manifold assembly316is configured to provide a flow of fluid, such as the flow of air192from the compressor section21such as depicted and described in regard toFIGS.4-5, to the thermal control rings314. Referring still toFIG.8and now also toFIGS.9-11, andFIG.14, further exemplary embodiments are provided. The embodiment depicted inFIG.8,FIG.9, andFIG.14may be configured similarly as one another, such as further described below.FIGS.9-11provide views of flows of fluid and openings at various cross-sections of an embodiment of the engine10at different circumferential positions of the engine10. Each of the embodiments may be formed via one or more manufacturing methods known in the art. InFIG.14, the embodiment provided may include double-wall structures that may be formed via an additive manufacturing process. Various embodiments provided herein may be formed as integral, unitary structures, such as via an additive manufacturing process or other appropriate manufacturing process. Referring to the various embodiments depicted inFIGS.8-11andFIG.14, the manifold assembly316is extended along the axial direction A forward and aft of the plurality of axially-spaced stages of the plurality of walls forming the thermal control rings314. In a particular embodiment, such as depicted inFIG.14, the manifold assembly316is extended aft along the axial direction A of the plurality of vanes310. In various embodiments, such as in the exemplary embodiment ofFIG.8, the manifold assembly316, the outer casing wall312, and the plurality of walls forming the thermal control rings314of the casing300is a single, integral, unitary structure, such as described herein. In particular embodiments, such as in the exemplary embodiment ofFIG.8, the manifold assembly316includes a plurality of concentric walls integrally formed and surrounding the outer casing wall312. In certain embodiments, the manifold assembly316includes an inner manifold1316radially inward of and concentric to an outer manifold2316. In still certain embodiments, the inner manifold1316is a double wall structure concentric to the outer manifold2316. Referring particularly toFIGS.9-10, certain embodiments of the casing300include a corrugated feature399. The corrugated feature399includes a shape defining ridges or grooves configured to mitigate formation of thermal expansion stresses at the casing300. In certain embodiments, the corrugated feature399is formed at the manifold assembly316. In a still particular embodiment, the corrugated feature399may be formed at an inner manifold1316or an outer manifold2316. The corrugated feature399may allow for the unitary, integral formation of the manifold assembly316with the outer casing wall312, such as described in various embodiments herein. Referring now briefly toFIG.15, the manifold assembly316includes a plurality of openings318surrounding the plurality of walls forming the thermal control rings314at the casing300. The plurality of openings318allow for the flow of fluid, depicted schematically via arrows91, to come into thermal communication with the thermal control rings314for desired heat transfer effect. In various embodiments, the plurality of openings318include an inlet opening3181configured to allow the flow of air91into a first cavity1321in thermal communication with the thermal control rings314, as described further below. The plurality of openings318may further include an outlet opening3182configured to allow at least a portion of the flow of air91, depicted schematically via flow of air92, to egress the first cavity1321and enter an inner wall conduit1326such as described further below. An inlet opening wall381is extended between an outer portion346and an inner portion347of the double wall structure formed by the inner manifold1316. The inlet opening wall381forms an inlet opening flowpath382that extends through the double wall structure fluidly separated from the inner wall conduit1326. The inlet opening3181and the inlet opening wall381allow for the flow of air91to pass from a conduit1324surrounding the inner manifold1316to enter a plenum383formed between adjacent thermal control rings314. Particularly, the inlet opening wall381extends between the outer portion346and inner portion347of the inner manifold1316. The inlet opening flowpath382formed by the inlet opening wall381allows the flow of air91to enter the plenum383while being fluidly segregated from the flow of air92through the inner wall conduit1326. Referring back particularly toFIGS.9-10, as discussed, the manifold assembly316includes the inner manifold1316surrounding the thermal control rings314along the circumferential direction C and the axial direction A. The manifold assembly316depicted further includes the outer manifold2316surrounding the inner manifold1316, as discussed above. A passage wall1318is extended to the outer manifold2316from the inner manifold1316to form a passage1320within the passage wall1318. In certain embodiments, such as depicted inFIG.8, the outer manifold2316of the manifold assembly316is extended along the axial direction A at or aft the plurality of vanes310. The outer manifold2316is further connected to the outer casing wall312at or aft of the plurality of vanes310. In still certain embodiments, such as depicted inFIGS.9-11, the inner manifold1316is extended to a location forward along the axial direction A of the plurality of vanes310(terminating forward of the plurality of vanes310). The inner manifold1316is also extended to a location aft along the axial direction A of the plurality of walls forming the thermal control rings314. As such, the inner manifold1316is connected to the outer casing wall312forward of the plurality of vanes310and aft of the thermal control rings314. The first cavity1321discussed above with reference toFIG.15(also depicted inFIGS.9-11) is formed between the inner manifold1316and the outer casing wall312. The thermal control rings314are surrounded by the inner manifold1316at a location within the first cavity1321between the inner manifold1316and the outer casing wall312. The passage1320allows for fluid communication with the first cavity1321between the inner manifold1316and the outer casing wall312. The passage1320further allows for the flow of air91to enter into thermal communication with the thermal control rings314. In various embodiments, the conduit1324briefly mentioned above is formed between the outer manifold2316and the inner manifold1316. The conduit1324is in fluid communication with the first cavity1321and is fluidly separated from passage1320by the passage wall1318. In particular embodiments, the passage wall1318is extended from the outer manifold2316to the inner manifold1316through the conduit1324. Referring particularly toFIGS.9-11, and further in regard toFIG.14, the conduit1324is further extended in fluid communication through one or more of the plurality of vanes310.FIG.10andFIG.14particularly depict the flow of air91entering into thermal communication and fluid communication with the thermal control rings314in the first cavity1321.FIG.10particularly depicts the flow of air91entering into thermal communication and fluid communication with the thermal control rings314in the first cavity1321. In various embodiments, the first cavity1321is formed to direct the flow of fluid to thermal contact portions of the thermal control rings directly, such as in a perpendicular direction.FIG.11andFIG.14particularly depict the flow of air92egressing from the first cavity1321through the conduit1324and then in serial flow through one or more of the plurality of vanes310(as airflow99, discussed below). In certain embodiments, the thermal control rings314are formed with the outer casing wall312to desirably improve clearance control. In one embodiment, such as depicted inFIG.13B, the thermal control ring314includes outer surfaces extended as a ridge, groove, or at acute or zig-zagging angles (see more detailed description below). Referring briefly particularly toFIG.14, and further depicted in the detailed perspective view inFIG.15, in certain embodiments, the inner manifold1316is a double wall structure forming the inner wall conduit1326between the double wall structure of the inner manifold1316. The inner wall conduit1326may extend in fluid communication to a second cavity1322formed between the outer casing wall312and an outer wall170of the core gas flowpath70. In such embodiments, the unitary, integral casing300, or furthermore integral to embodiments of the manifold assembly316, allow for separate flows into the plurality of vanes310. Particularly, the flow of air91enters the conduit1324from a compressor section such as depicted and described with regard toFIGS.1-6. A portion of the flow of air91, depicted via arrows92, flows into the first cavity1321and then into the inner wall conduit1326formed at the double wall structure. The flow of air92then flows into one or more of the plurality of vanes310. Furthermore, another portion of the flow of air91, depicted via arrows99, remains in the conduit1324and flows into one or more of the plurality of vanes310. In certain embodiments, the flows92,99are isolated or fluidly separated from one another until mixing at the plurality of vanes310. In other embodiments, the flows92,99remain fluidly separated and are provided to separate respective vanes310, or separate conduits within each vane310. Embodiments of the casing300and the manifold assembly316allow for improved thermal efficiency and improved overall engine efficiency, such as via providing secondary uses of the flow of fluid after thermal communication with the thermal control rings314, rather than outputting the flows to atmosphere or to an under-cowl area of the engine. In certain embodiments, the outer wall170of the core gas flowpath70forms the outer shroud segment77of the shroud assembly72. The outer shroud segment77is exposed to the core gas flowpath70, and may include thermal barrier coatings or materials configured to withstand heat from the combustion gases. The outer shroud segment77may further be configured to at least partially rub with one or more stages of blades at the core gas flowpath70. Referring still toFIG.14, and further depicted inFIG.15,FIG.16providing a side view of the casing300ofFIG.15, andFIG.17providing a close-up view of Section A inFIG.16, the inner manifold1316includes a plenum wall1319extended from the inner manifold1316and surrounding the thermal control ring314. In certain embodiments, the plenum wall1319is extended radially inward from the inner portion347of the inner manifold1316. The plenum wall1319may be formed as an integral, unitary, or monolithic structure with the inner manifold1316including the outer portion346and the inner portion347. The first cavity1321is formed between an outer surface1325of the thermal control ring314and the plenum wall1319. Referring particularly toFIGS.16and17, the thermal control ring314includes a wall or body332extended outward, such as outward along the radial direction R, from the outer casing wall312. In various embodiments, such as described above with regard to the plurality of thermal control rings314, the body332is extended substantially annularly along the circumferential direction C (FIGS.1-3). Referring more particularly toFIG.17, the body332forms an internal flowpath330to allow a flow of fluid through the thermal control ring314. The flow of fluid through the body332allows for a temperature or thermal gradient at the thermal control ring314to be desirably controlled, altered, or modulated by changes in temperature or flow rate of the flow of fluid through the flowpath330at the body332. The flow of fluid through the body332may furthermore allow for one or more structures attached or integrally formed to the thermal control ring314, such as the outer casing wall312or the shroud assembly72, to move based at least in part on thermal changes provided by the flow of fluid, such as to desirably control the clearance gap CL (FIG.8) between the rotor blades58,68and the shroud assembly72. Referring still toFIG.17, the exemplary casing300depicted further includes a plurality of pins334extended along a radial direction R of the engine10incorporating the casing300from the outer casing wall312to the body332. Referring briefly also toFIG.18, a top-down view of the plurality of pins334depicts each pin334is depicted. As shown inFIGS.17and18, each pin334spaced apart from one another along an axial direction A of the engine10incorporating the casing300and along a circumferential direction C of the engine10incorporating the casing300(FIG.18). In such a manner, adjacent pins334define a space336therebetween. Referring back particularly toFIG.17, the flowpath330extended radially through the body332is further extended in fluid communication to the gap or space336provided between the plurality of pins334. The thermal control ring314may form the flowpath330as a plurality of discrete, round or slotted flowpaths in adjacent arrangement along the circumferential direction C. In other embodiments, the thermal control ring314forms the flowpath330as a plurality of arcuate sections extended at least partially along the circumferential direction C. The flow of air, depicted schematically via arrows91is received and provided in fluid communication with the thermal control rings314in accordance with any one or more embodiments depicted and described above with regard toFIGS.1-15. During operation, the flow of air91passes through the spaces336and across the plurality of pins334to enter into the flowpath330within the body332. During operation, the flow of air91progresses radially through the body332and egresses the body332through an outlet opening338at the flowpath330. The outlet opening338is formed by the body332distal to the spaces336to allow for fluid communication from the flowpath330to the inner wall conduit1326formed within the double wall structure of the inner manifold1316. The flow of fluid egressed from the thermal control ring314, depicted schematically via arrows92, may flow through the inner wall conduit1326in accordance with any one or more embodiments depicted and described with regard toFIGS.1-15. Referring still toFIG.17, in various embodiments, a seal1323is positioned to contact the outer surface1325of the thermal control ring314and the plenum wall1319. Additionally, or alternatively, the seal1323may be formed or positioned in contact with the inner portion347of the inner manifold1316and the outer surface1325of the body332of the thermal control ring314. The seal1323inhibits a flow of fluid through the first cavity1321. In a particular embodiment, the seal1323may form a structural member configured to provide structural support to the inner manifold1316and/or the thermal control ring314. The seal1323may further support the body332relative to the plurality of pins334. In certain embodiments, the seal1323is a braze, weld, or other member attaching the plenum wall1319to the thermal control ring314at the first cavity1321. It should be appreciated that the seal1323and the plenum wall1319may each extend substantially co-directional with the thermal control ring314as either a monolithic annular component or as a plurality of arcuate sections positioned in circumferential arrangement. In particular embodiments, the outer casing wall312, the plurality of pins334, and the body332of the thermal control rings314are a unitary, integral structure, such as may be formed by an additive manufacturing process, or other appropriate manufacturing process. In still particular embodiments, the inner portion347, the outer portion346, and the plenum wall1319are together formed as a unitary, integral structure of the inner manifold1316. In certain embodiments, the thermal control rings314and outer casing wall312are a unitary structure separate from the inner manifold1316. In still certain embodiments, the unitary structures are formed from an additive manufacturing process. Referring now toFIG.19, an exemplary embodiment is provided depicting an operation of the engine10. The embodiment provided inFIG.19is configured substantially similarly to the embodiment depicted and described with regard toFIG.16. Operation of the system provided here may be based substantially as described with regard to embodiments of the engine10as depicted and described with regard toFIGS.1-6andFIGS.7A-7B. InFIG.19, the flow of air91is received at the second location272, such as an opening provided through the outer manifold2316. The flow of air91is received into the conduit1324formed between the outer manifold2316and the inner manifold1316. The flow of air91is routed into the plenum383via the inlet opening1381formed through the inner manifold1316. The flow of air91is routed across the plurality of pins334and through the flowpath330(seeFIG.17) into the inner wall conduit1326(seeFIG.17). In one embodiment, such as depicted inFIG.19, the flow of air92may egress from the inner wall conduit1326to outside of the casing300or engine10, such as depicted via arrows93through opening1380. The flow of air93may egress heat or thermal energy from the thermal control rings314to an atmospheric condition, or to an under-casing or under-cowl area. Referring now toFIG.20, a perspective view of a portion of the engine10is provided. The embodiment provided inFIG.20is configured substantially similarly to the embodiment described with regard toFIGS.16-19. In particular,FIG.20depicts a plurality of discrete flowpaths330extended in adjacent circumferential arrangement through the thermal control rings314. A plurality of outlet openings3182is formed through the inner portion347of the inner manifold1316corresponding to the plurality of flowpaths330and outlet openings338at the thermal control rings314. The engine10may accordingly form a plurality of flowpaths330and outlet openings338at the thermal control rings314in adjacent arrangement along the circumferential direction C corresponding to the plurality of outlet openings3182formed through the inner portion347of the inner manifold1316. Such arrangement may allow for the flow of air92to egress from within the thermal control ring314into the inner wall conduit1326. Referring now toFIG.21, a side cross-sectional view of the embodiment provided inFIG.20is provided. The embodiment inFIG.21further depicts the inner wall conduit1326in fluid communication with the second cavity1322positioned at the turbine frame308. An opening3112is formed through the turbine frame308to allow the flow of air92to egress into thermal communication with the turbine frame308. Referring briefly now back toFIG.12andFIGS.13A-13D, additional aspects of the present disclosure are described.FIG.12provides a partial circumferential view of an embodiment of the manifold assembly316.FIGS.13A-13Dfurthermore provide sectional views of the embodiment depicted inFIG.12(labels for each ofFIGS.13A-13Dare indicated inFIG.12). As previously described, various embodiments of the manifold assembly316are formed via one or more additive manufacturing processes. Referring particularly toFIG.12and the close-up view ofFIG.13C, in various embodiments, a member3316is extended to the inner manifold1316and the outer manifold2316. The member3316is extended at an acute angle (e.g., a V-, Z-, or other angled cross-section) from the inner manifold1316to the outer manifold2316. In various embodiments, the member3316is extended along a first direction, depicted schematically via arrows95, and a second direction opposite of the first direction, depicted schematically via arrows96. Embodiments of the improved turbine casing300, turbine section27, and engine10provided herein allow for improved clearance control, cooling fluid distribution, reduced weight, and improved engine efficiency. Embodiments of the engine10, the casing300, and manifold assembly316provided herein include integral, unitary structures, such as the casing extended over the stages of the high speed turbine, or further including the inter-turbine frame, or further including all or part of the manifold, such as may be formed by additive manufacturing processes that would not have heretofore been possible or practicable. Embodiments depicted and described herein allow for improved and advantageous positioning of thermal control rings314, flowpaths330therethrough, and the plurality of pins334, for improved clearance control response, improved formation and positioning of openings, passages, and conduits to allow for more efficient heat transfer fluid utilization and movement, and reduced weight, such as via obviating flanges and sub-assemblies into integral components. Particular combinations of these features allow for improved heat transfer properties and reduced thermal gradients. Improved heat transfer properties particularly include lowering a heat transfer coefficient at certain features, such as the plurality of walls, body, pins, and/or flowpaths forming the thermal control rings314, in contrast to known clearance control systems. Such improvements may mitigate or eliminate undesired or excessive deformation, ovalization, bowing, or other changes in geometry of the casing300that may adversely affect deflections or result in undesired contact to the turbine rotor blades58at the high speed turbine28. Embodiments of the engine10and the casing300provided herein include an integral, unitary casing for the high speed turbine28together with a turbine center frame or mid-turbine frame308, formed by the outer casing wall312and the plurality of vanes310and positioned downstream along the core gas flowpath70of the high speed turbine28and upstream along the core gas flowpath70of a low- or intermediate-pressure turbine, such as depicted at turbine30. Embodiments provided herein further include e.g., an integral, unitary clearance control manifold configured to provide heat transfer fluid to thermal control rings. The integral, unitary structures may further allow for improved positioning of the thermal control rings relative to the turbine rotors, such as to provide improved clearance control across the turbine rotor assembly. It should be appreciated that the conduits110,120,123, flow control devices130, or heat exchangers141,142depicted and described with regard toFIGS.1-6may be provided to the casing300, manifold assembly316, and other structures depicted and described with regard toFIGS.8-21. However, various embodiments of the engine10provided herein may include one or more of the conduits110,120,123, flow control devices130, or heat exchangers141,142providing flows of air to any appropriate clearance control system, turbine section, or bearing assembly. Such structures, when combined with any appropriate clearance control system, turbine section, or bearing assembly, may provide one or more advantages and benefits described herein. Alternatively, various embodiments of the engine10provided herein may include one or more of the casings300or the manifold assemblies316receiving flows of air from any appropriate conduits, passageways, flowpaths, tubes, or other structures. Such structures, when combined with any appropriate conduit or heat exchanger, may provide one or more advantages and benefits described herein. Benefits and advantages described with regard to either the conduits, flow control devices, heat exchangers, casings, or manifolds, when combined together, may compound such benefits and advantages described herein. Embodiments of the conduits110,120,123and heat exchangers141,142provided herein may be formed, at least in part, by one or more additive manufacturing processes such as described herein. For instance, the first heat exchanger141may be integrally formed with the first conduit110, or the second heat exchanger142may be integrally formed with the second conduit120, or portions thereof. In another instance, all or part of the first conduit110, including one or more inlet manifolds111, outlet manifolds112, or collectors115may be integrally formed as a single, unitary component. In still another instance, all or part of the second conduit120, including one or more inlet portions121or outlet portions122may be formed as a single, unitary component. Still further, certain combinations of portions of the first conduit110, second conduit120, and third conduit123may be formed integrally to one another. For instance, the outlet manifold112may be formed as a single, unitary component with the inlet portion121. In another instance, casings surrounding the compressor section21may be formed integrally with the inlet manifold111. The collector115may be formed integrally with the first heat exchanger141. The second heat exchanger142may be formed integrally with the outlet portion122. This written description uses examples to disclose the preferred embodiments, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. Further aspects of the disclosure are provided by the subject matter of the following clauses: A method of operating a gas turbine engine having a compressor section and a turbine section in serial flow arrangement, a first conduit in fluid communication with the compressor section and the turbine section, a first heat exchanger positioned in thermal communication with a flow of air through the first conduit, a second conduit in fluid communication with the first conduit at a location downstream of the first heat exchanger and in fluid communication with a second location at the turbine section, and a flow control device positioned in flow communication with the second conduit, the method comprising: extracting the flow of air from the compressor section into the first conduit; flowing the extracted flow of air through the first conduit to the a first location at the turbine section, wherein the second conduit is in fluid communication with the turbine section at a second location; flowing a heat transfer fluid to the first heat exchanger, the heat transfer fluid in thermal communication with the extracted flow of air through the first conduit via the first heat exchanger; and modulating, via the flow control device, a portion of the flow of air extracted from the first conduit to the second conduit downstream of the first heat exchanger. The method of one or more of these clauses, further comprising: operating the engine between approximately 75% and approximately 90% of an overall power output of the engine. The method of one or more of these clauses, wherein extracting the flow of air from the compressor section comprises extracting the flow of air from the compressor section at a compressor location having an airflow pressure between approximately 20 pounds per square inch and approximately 60 pounds per square inch while operating the engine between approximately 75% and approximately 90% of the overall power output. The method of one or more of these clauses, further comprising: operating the engine at an operating condition corresponding to between approximately 55% and approximately 75% of an operating envelope; and wherein extracting the flow of air from the compressor section comprises extracting the flow of air from the compressor section at a compressor location having an airflow pressure between approximately 20 pounds per square inch and approximately 60 pounds per square inch during the operating condition corresponding to between approximately 55% and approximately 75% of the operating envelope. The method of one or more of these clauses, wherein the compressor section comprises a low speed compressor and a high speed compressor, and wherein the turbine section comprises a low speed turbine, a high speed turbine, and a turbine frame positioned between the low speed turbine and the high speed turbine, and wherein the first location at the turbine section is at the turbine frame, and wherein the first conduit extends in fluid communication from the high speed compressor to the turbine frame. The method of one or more of these clauses, wherein the first conduit is configured as a fixed area flowpath from the compressor section to the turbine section, and wherein the flow control device defines a variable area flowpath at the second conduit, and wherein flowing the extracted flow of air through the first conduit to the first location at the turbine section is a continuous flow through an operating condition of the engine, and wherein modulating the portion of the flow of air extracted from the first conduit to the second conduit comprises providing a variable flow to the second location at the turbine section. The method of one or more of these clauses, wherein the gas turbine engine further comprises: a clearance control system positioned at the second location at the turbine section; and wherein the method further comprises: selectively altering a tip clearance at the clearance control system based on the portion of the flow of air extracted from the first conduit to the second conduit. The method of one or more of these clauses, wherein the gas turbine engine comprises: a third conduit extended from the flow control device and in fluid communication with a third location at the turbine section; wherein the method further comprises: modulating, via the flow control device, a second portion of the flow of air extracted from the first conduit to the third conduit extended from the flow control device. The method of one or more of these clauses, wherein the gas turbine engine further comprises: a fan section, wherein a bypass airflow passage is formed downstream of the fan section and around an outer casing surrounding the compressor section and the turbine section; and a second heat exchanger positioned at the second conduit downstream of the flow control device and upstream of the second location at the turbine section, wherein the second heat exchanger allows for thermal communication of a flow of bypass air from the bypass airflow passage with the portion of the flow of air extracted to the second conduit; wherein the method further comprises: thermally communicating, via the second heat exchanger, the flow of bypass air with the portion of the flow of air extracted to the second conduit. A gas turbine engine, the gas turbine engine comprising: a compressor section and a turbine section in serial flow arrangement; a first conduit extended from the compressor section to the turbine section, the first conduit in fluid communication with the compressor section and the turbine section to communicate a flow of air from the compressor section to a first location at the turbine section; a first heat exchanger positioned in thermal communication with the flow of air through the first conduit; a second conduit in fluid communication with the first conduit at a location downstream of the first heat exchanger and in fluid communication with a second location at the turbine section; and a flow control device positioned in flow communication with the second conduit for selectively changing an amount of the flow of air from the first conduit through the second conduit. The gas turbine engine of one or more of these clauses, wherein the second conduit comprises an inlet portion and an outlet portion, wherein the inlet portion is fluidly coupled to the first conduit and the flow control device, and wherein the outlet portion is fluidly coupled to the flow control device and the second location of the turbine section. The gas turbine engine of one or more of these clauses, the gas turbine engine comprising: a second heat exchanger in thermal communication with a flow of air through the outlet portion of the second conduit and upstream of the second location at the turbine section. The gas turbine engine of one or more of these clauses, the gas turbine engine comprising: a fan section, wherein a bypass airflow passage is formed downstream of the fan section and around an outer casing surrounding the compressor section and the turbine section, wherein the fan section provides a flow of bypass air to the bypass airflow passage during operation of the gas turbine engine, and wherein the second heat exchanger provides the flow of bypass air at the bypass airflow passage into thermal communication with the flow of air at the outlet portion of the second conduit. The gas turbine engine of one or more of these clauses, the gas turbine engine comprising: a third conduit extended in fluid communication from the flow control device to a third location at the turbine section. The gas turbine engine of one or more of these clauses, wherein the flow control device is a three-way valve configured to selectively change the amount of the flow of air from the first conduit through an inlet portion of the second conduit, and wherein the flow control device is configured to egress at least a portion of the flow of air to the third conduit, an outlet portion of the second conduit, or both. The gas turbine engine of one or more of these clauses, the turbine section comprising: a first turbine assembly surrounded by an outer wall forming a gas flowpath, and wherein the first turbine assembly comprises an outer casing wall surrounding the outer wall, wherein the outer wall and the outer casing wall together form a cavity, and wherein the third location at the turbine section is at the cavity. The gas turbine engine of one or more of these clauses, the turbine section comprising: a first turbine assembly; a clearance control system, wherein the second location at the turbine section is at the clearance control system and wherein the clearance control system is operably coupled to the first turbine assembly; and a turbine frame positioned in serial flow arrangement downstream of the first turbine assembly, and wherein the first location at the turbine section is at the turbine frame. The gas turbine engine of one or more of these clauses, the gas turbine engine comprising: a fluid system configured to provide a flow of heat transfer fluid in thermal communication with the flow of air via the first heat exchanger. The gas turbine engine of one or more of these clauses, wherein the first conduit comprises: a plurality of inlet manifolds configured to receive the flow of air from a plurality of circumferential compressor locations at the compressor section; and a collector configured to receive the flow of air from the plurality of inlet manifolds, and wherein the collector is fluidly coupled to the first heat exchanger to provide the flow of air in thermal communication to the first heat exchanger. An airflow delivery system for a gas turbine engine, the gas turbine engine comprising a compressor section and a turbine section in serial flow arrangement, the airflow delivery system comprising: a first conduit configured to extend from the compressor section to the turbine section in flow communication with the compressor section and the turbine section to communicate a flow of air from the compressor section to a first location at the turbine section when installed in the gas turbine engine; a first heat exchanger positioned to be in thermal communication with the flow of air at the first conduit; a second conduit extending from the first conduit downstream of the first heat exchanger, wherein the second conduit is configured to extend in fluid communication to a second location at the turbine section; and a flow control device positioned at the second conduit, wherein the flow control device is configured to selectively change an amount of the flow of air from the first conduit through the second conduit. | 108,583 |
11859501 | DETAILED DESCRIPTION FIG.1schematically illustrates a gas turbine engine20. The gas turbine engine20is disclosed herein as a two-spool turbo fan that generally incorporates a fan section22, a compressor section24, a combustor section26and a turbine section28. The fan section22drives air along a bypass flowpath while the compressor section24drives air along a core flowpath for compression and communication into the combustor section26then expansion through the turbine section28. Although depicted as a turbofan in the disclosed non-limiting embodiment, it should be appreciated that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engine architectures such as turbojets, turboshafts, and three-spool (plus fan) turbofans. The engine20generally includes a low spool30and a high spool32mounted for rotation about an engine central longitudinal axis X relative to an engine static structure36via several bearing structures38. The low spool30generally includes an inner shaft40that interconnects a fan42, a low pressure compressor (“LPC”)44and a low pressure turbine (“LPT”)46. The inner shaft40drives the fan42directly or through a geared architecture48to drive the fan42at a lower speed than the low spool30. An exemplary reduction transmission is an epicyclic transmission, namely a planetary or star gear system. The high spool32includes an outer shaft50that interconnects a high pressure compressor (“HPC”)52and high pressure turbine (“HPT”)54. A combustor56is arranged between the high pressure compressor52and the high pressure turbine54. The inner shaft40and the outer shaft50are concentric and rotate about the engine central longitudinal axis A which is collinear with their longitudinal axes. Core airflow is compressed by the LPC44then the HPC52, mixed with the fuel and burned in the combustor56, then expanded over the HPT54and the LPT46. The turbines54,46rotationally drive the respective low spool30and high spool32in response to the expansion. The main engine shafts40,50are supported at a plurality of points by bearing structures38within the static structure36. It should be appreciated that various bearing structures38at various locations may alternatively or additionally be provided. With reference toFIG.2, an enlarged schematic view of a portion of the turbine section28is shown by way of example; however, other engine sections will also benefit herefrom. A full ring shroud assembly60within the engine case structure36supports a blade outer air seal (BOAS) assembly62with a multiple of circumferentially distributed BOAS64proximate to a rotor assembly66(one schematically shown). The full ring shroud assembly60and the BOAS assembly62are axially disposed between a forward stationary vane ring68and an aft stationary vane ring70. Each vane ring68,70includes an array of vanes72,74that extend between a respective inner vane platform76,78and an outer vane platform80,82. The outer vane platforms80,82are attached to the engine case structure36. The rotor assembly66includes an array of blades84circumferentially disposed around a disk86. Each blade84includes a root88, a platform90and an airfoil92(also shown inFIG.3). The blade roots88are received within a rim94of the disk86and the airfoils92extend radially outward such that a tip96of each airfoil92is closest to the blade outer air seal (BOAS) assembly62. The platform90separates a gas path side inclusive of the airfoil92and a non-gas path side inclusive of the root88. With reference toFIG.3, the platform90generally separates the root88and the airfoil92to define an inner boundary of a gas path. The airfoil92defines a blade chord between a leading edge98, which may include various forward and/or aft sweep configurations, and a trailing edge100. A first sidewall102that may be convex to define a suction side, and a second sidewall104that may be concave to define a pressure side are joined at the leading edge98and at the axially spaced trailing edge100. The tip96extends between the sidewalls102,104opposite the platform90. It should be appreciated that the tip96may include a recessed portion. A remote temperature measurement system200generally includes a control system202, an optical emitter/receiver204, and, in the blade84, a probe system206. Although the term “optical” is used throughout, other areas in the electromagnet region may be utilized. That is, the optical emitter/receiver204is in a fixed frame of reference adjacent to the blade84. The optical emitter/receiver204can include a miniaturized spectroscope, or other such optical device. The optical emitter/receiver204may operate in at least one of a ultraviolet, visible, infrared, and microwave region of the electromagnetic spectrum. The probe system206may include one or more resonant probes210that communicate with the optical emitter/receiver204via an optical port212. The optical port212communicates with the resonant probe210via a waveguide214. The optical port212and the associated optical emitter/receiver204may be located remote from the resonant probe210within the blade84. That is, temperature measurements may be taken in the blade84that are remote from the optical port212and the associated optical emitter/receiver204which may then be located in a relatively more benign environment. In one embodiment, the optical port212in each blade84may be located in a radial position such that multiple resonant probes210can communicate with the optical emitter/receiver204as the blades rotate thereby to place each optical port212within a field of view F of the optical emitter/receiver204. Each blade84may be formed by additive manufacturing which readily permits installation of the probe system206during the additive manufacture process. It should be appreciated that although a blade84with an internal cooling circuit110(shown schematically;FIG.4) will be described and illustrated in detail, other hot section components including, but not limited to, vanes, turbine shrouds, end walls, BOAS, combustors, and other such components will also benefit here from either with or without internal cooling circuits110. Embedding the resonant optical probe system206inside the component prevents damage (e.g. peel off, corrosion etc.) to the probe system206due to harsh environmental conditions (e.g., high pressure, high temperature gas flow, foreign particles etc.). In addition, the probe system206will not affect the aerodynamics of the part like a coating or painted material would do. Preventing the exposure of the probe system206to engine harsh environment also reduces material compatibility issues (e.g. potential contamination of engine parts due to a new probe material degrading over time etc.) and provide additional flexibility when selecting probe materials. The control system202may include at least one processor220(e.g., a controller, microprocessor, microcontroller, digital signal processor, etc.), memory222, and an input/output (I/O) interface224. The processor220and the I/O interface224are communicatively coupled to the memory222. The memory222may be embodied as any type of computer memory device (e.g., volatile memory such as various forms of random access memory) which stores data and control algorithms such as the logic described herein. The I/O interface224is communicatively coupled to a number of hardware, firmware, and/or software components, including, for example, the remote systems120such as a ground station, Health and Usage Monitoring Systems (HUMS), condition-based maintenance (CBM) system, or other system. Numerous systems may use a condition-based maintenance (CBM) philosophy where sensor input is used to schedule maintenance rather than scheduled maintenance to reduce maintenance labor burden and associated costs. With reference toFIG.5, a method300for manufacture of the resonant probes210initially includes utilization of a substrate250with thermal properties matching the host material of the blade84or other component (302;FIG.6). The substrate can be, for example sapphire, MgO, etc. when optical transparency is needed. Otherwise the substrate material can be the same as the component material, with a variation in microstructure and composition, to reduce mismatch in thermal properties. When the probe substrate is the same as the component material, additional surface smoothing may be applied. Next, optical resonators252are applied, with, for example, thin film deposition and patterning techniques to provide, for example, micro/nano structures (step304ofFIG.5, and see alsoFIG.7). The optical resonators252can include, for example, metals, metal alloys, metalloids, intermetallics, ceramics, carbon-based materials and other metallic materials such as titanium nitride, zirconium nitride etc., and the dielectric materials can include, for example, SiO2, Si3N4, SiC, synthetic diamonds, etc. There need be no difference between dielectric and metallic nanostructures or thin films in terms of fabrication. Both can be manufactured following similar steps and equipment—usually a mixture of patterning (e.g. lithography and etching) and film deposition techniques (physical vapor deposition, chemical vapor deposition, etc.). Next, the optical resonators252are covered with a protective material254to encapsulate the optical resonators252(step306inFIG.5, see alsoFIG.8). One or both of the substrate250and the protective material254may be transparent in the desired wavelength ranges that will be used for measurement. The resonant probes210are essentially antennas for light. Changes in temperature affect the optical properties of the resonant probes210such that application of a spectral source from the optical emitter/receiver204results in a change in reflected electromagnetic radiation spectrum and amplitude. The optical resonators252are designed for resonance in the spectral regions of interest; which can be determined by a variety of factors including background radiation noise, transmission/scattering/absorption properties of the working environment, etc. Changes in temperature thereby result in a change in reflected signal. In another embodiment, a stack of thin film optical materials260(FIG.9) can be utilized as the resonant probe210to provide cavity resonances. Changes in the optical property and thickness of individual layers as a function of temperature can be employed for temperature sensing based on reflection of the incident electromagnetic energy from the emitter/receiver. The resonant probes can include one or more components made of luminescent materials, such as thermographic phosphors, that indicate changes in temperature via a change in the luminescence signal. Luminescent material can be applied as an addition to thin film cavity resonators or nanostructured antenna resonators to enhance the sensing capabilities. Luminescent material can also be applied without other resonating structures to act as the single source of temperature indicating signal Luminescence data provides a change in temporal response whereas reflection data provides a change in spectral response. Therefore, these two mechanisms can be used together for enhanced measurement capabilities. In another embodiment, the resonant probe210can include a stacked thin film resonant cavity,260, (e.g. Fabry-Perot or etalon) to define field localization and reflection/absorption/transmission resonance peaks. Two semi-transparent metallic thin films,262, with thicknesses ranging between 1 nm to 50 nm form the cavity walls and a thermographic phosphor232fills the optical cavity with thickness ranging from 1 nm to 5 micrometer. Multiple films and cavities can be combined to provide additional resonance bands. Resonant nano/micro-structures252(FIG.8) (e.g., metal nanodisks with a diameter ranging from 10 nm to 1 micrometer, and a height ranging from 5 nm to 1 micrometer) can be further embedded into the thermographic phosphor232to provide additional sensing capabilities. The entire resonant probe can be built on a substrate material that is the same as the additively manufactured component (e.g. IN-738 for an Inconel blade) with a surface roughness ranging from 0.3 nm to 100 nm. The resonant probe210can be further encapsulated with an Al2O3film of thickness ranging from 10 nm to 5 micrometer. With reference toFIG.10, a method400for operation of the remote temperature measurement system200is disclosed in terms of functional block diagrams. The functions of the logic are programmed software routines capable of execution in various microprocessor based electronics control embodiments and represented herein as the block diagrams. These functions may be enacted in either dedicated hardware circuitry or programmed software routines capable of execution in a microprocessor-based electronics control embodiment. In one embodiment, the resonant probe210is embedded in a component of interest (402) such that the optical port212is within a line-of-sight of the optical emitter/receiver204(404). The optical emitter/receiver204may thereby be located outside of a relatively harsh environment that is to be monitored. The optical emitter/receiver204communicates with the optical port212which guides the electromagnetic beam to the resonant probe210via the waveguide214(406). The optical emitter/receiver204then monitors the reflected signal in real time for interrogation by the control system202to calculate temperature data. In one embodiment, the control system202may operate in a reflection mode. The reflection mode may utilize electromagnetic radiation with a broad spectrum that is communicated to the resonant probe210. The resonant probe210has certain resonant reflection peak and dips that are defined by design. These resonances shift as a function of temperature. Measuring the reflected signal permits real time measurement of the current temperature of the resonant probe210and surrounding medium to obtain the temperature data (FIG.11). In another embodiment which utilizes an optical material such as the thermographic phosphors, the control system202may operate in a luminescence mode. The luminescence mode utilizes pulsed monochromatic (single wavelength) electromagnetic radiation that is sent on to the resonant probe210and absorbed by the luminescent material. Decaying electromagnetic radiation with lower energy is emitted by the resonant probe210. The decay characteristics (intensity) of the emitted electromagnetic radiation is a function of temperature and it can be used to measure the temperature of the resonant probe210and surrounding material to obtain the temperature data (FIG.12). Algorithms established in the control system then utilize the temperature data for condition-based maintenance, reduced product development cycle, design optimization, or other analysis of the component (404). The remote temperature measurement system200uses engineered resonant optical probes embedded in additively manufactured components for real time remote temperature measurement via free-space coupling of electromagnetic probes that enables access to moving parts. In addition to wear/rub surfaces, other static components that become hot from aerothermal heating or combustion such as leading edges, fins, inlets, cowls, combustor walls, exhausts, isolators of ramjets, scramjets, rotation detonation engines, rocket motors, etc., may also benefit herefrom. Other locations within harsh environments applications including ground turbines, power plants (coal and other), industrial furnaces, drilling tools/applications, hypersonic vehicle sensing. The free-space approach allows the use of a broad electromagnetic spectrum with an additional degree of freedom to address application-specific concerns such as background radiation, or signal attenuation due to operational environment (e.g., soot and gas absorption). Resonant probes leverage both temperature dependence of inherent material properties (e.g. dielectric constant, fluorescent lifetime) and structural engineering (e.g. antennas, gratings, cavities) for enhanced, real-time sensing. The free space coupling enables measurements from parts otherwise inaccessible (e.g., extreme conditions, moving parts). Real-time accurate measurements using resonant optical probes in extreme environments provide critical information for improved design (e.g., higher efficiency, smaller safety margins) and accurate maintenance schedules (e.g., increased reliability and availability factors, minimized forced outage rates and mean time to repair, minimized secondary failures). Although particular step sequences are shown, described, and claimed, it should be appreciated that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure. The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in electromagnetic radiation of the above teachings will fall within the scope of the appended claims. It is therefore to be appreciated that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content. | 17,435 |
11859502 | DESCRIPTION OF EMBODIMENTS For the description of the invention, the radial, longitudinal and transverse orientations according to the reference R, L, T indicated in the figures will be adopted in a non-limiting manner. FIG.1represents a part of a turbine engine, particularly a high- or low-pressure compressor. This compressor40has a main axis A extending along the main longitudinal direction of the turbine engine. The compressor40includes several stages each of which includes a set of mobile vanes42borne by a rotor disk and a plurality of stator vanes14forming a stator44intended to redirect the air flow along the main axial direction of the compressor. The main orientation of each blade14of the stator44is radial in relation to the main axis A of the compressor40, i.e. each vane extends along the radial direction R perpendicular to the longitudinal direction L. It will be understood that the vane can be slightly inclined in relation to the radial direction R, due to the local inclination of the air flow jet wherein the vane14is located. The stator44is of the variable-pitch type, i.e. each stator vane14is pivotally movable about the main axis thereof, which extends here along the radial direction R, to modify the inclination thereof in relation to a plane defined by the longitudinal direction L and the radial direction R of the vane14, i.e. in relation to the overall flow direction of the air flow in the compressor40. It will be understood that not all the stator vanes14of the turbine engine are variable-pitch. Thus, only the stator vanes14of the first stages of the compressor40are mobile, the vanes forming the other stators are stationary in the stator. In the following description, reference will solely be made to a mobile vane14, i.e. a variable-pitch vane. Consequently, the term vane14will solely be used to describe this mobile vane14. It will be understood that when the vane14is pivoted in the compressor40, the reference R, L, T which is associated therewith pivots in the same way about the radial direction R. As can be seen in more detail inFIG.2, each vane14includes a radially inner plate16which delimits, with a stationary wall17of the compressor40, the radially inner part of the air flow jet. The vane14also includes a radially outer plate18(seen inFIG.1), which delimits, with a stationary wall19of the compressor40, the radially outer part of the air flow jet. Since the vane14is a variable-pitch vane, each plate16,18is in the main form of a disk coaxial with the radial axis of rotation of the vane14in relation to the stationary platforms of the compressor. Each plate16,18includes an annular peripheral wall20which is centred on the radial axis of rotation and which is located in a complementary circular orifice21formed in the associated stationary platform. Each plate16,18also includes a transverse longitudinal wall22which extends essentially longitudinally and transversally and which faces the other plate16,18. Each transverse longitudinal wall22extends essentially in the extension of the annular wall of the association platform, to reconstitute the air flow jet. The vane14includes a blade12which extends along the main axis of the vane14, i.e. here in the radial direction R between the two plates16,18. The blade12includes an upstream longitudinal end edge24commonly referred to as the leading edge, a downstream longitudinal end edge26commonly referred to as the trailing edge, a lower surface wall28and an upper surface wall30which transversally delimit the blade12and which extend longitudinally between the leading edge24and the trailing edge26and radially between the two transverse longitudinal walls22of the plates16,18. During the operation of the turbine engine, and as can be seen inFIG.4, the air flow in the jet produces disturbances32at the connection between each end of the blade12and the transverse longitudinal wall22of a plate16,18, i.e. at the connection between the lower surface wall28or the upper surface wall30with the transverse longitudinal wall22of a plate16,18. Here, only the disturbances between the upper surface wall30and the transverse longitudinal wall22of the radially inner plate16have been represented. These disturbances32, which take the form of vortices, tend to increase along the flow direction, i.e. from upstream to downstream, i.e. they are greater on approaching the trailing edge of the blade12. To limit the expansion of the disturbances32in the downstream direction, and as can be seen inFIGS.4to6, each transverse longitudinal wall22of a plate16,18, includes at least one fin34which extends by protruding in relation to said transverse longitudinal wall22along the radial direction. The fin34forms an obstacle to the vortex flow formed at the plate16, preventing the disturbance32from growing further, or even inducing the formation of several disturbances33of lesser amplitude. According to a preferred embodiment represented in the figures, the transverse longitudinal wall22of the plate16includes two fins34which are distributed transversally on either side of the blade12. It will be understood that the invention is not limited to this embodiment, and that a different number of fins34can be disposed on either side of the blade12. Each fin34extends substantially parallel with the blade12, i.e. in a plane parallel with the longitudinal L and vertical V directions in the embodiment represented in the figures. The fin is located transversally facing the lower surface wall28or the upper surface wall30and it extends transversally away from this wall28,30of the blade12. The cross-section of each fin34along a transverse longitudinal plane can be rectilinear, or curved, and in this case, the curvature of the fin34is similar to the curvature of the lower surface wall28or the upper surface wall30, beside which the fin34is located. Thus, in the latter case, the fin34follows the flow direction of the air flow in the stator. Each fin34is delimited by a radial end face36and two lateral faces38which are separated from one another by the radial end face36. The cross-section of the fin34along a transverse radial plane, i.e. along the directions R, T is thus substantially rectangular. According to an alternative embodiment, the sharp angles of the ridges of each fin34are replaced by fillets, thus forming a fin34with rounded edges. The lateral faces are preferably parallel with one another and parallel with the radial direction R of the vane14. The radial dimension of the fin34is variable and increasing along the longitudinal direction. The radial end face36is preferably rounded along the radial direction. Preferably, the maximum radial dimension of each fin is less than 25% of the radial dimension of the blade12, i.e. less than 25% of the radial distance between the transverse longitudinal walls22of the plates16,18. This radial dimension is sufficient to combat the vortices, which are of the same order of dimension as this radial dimension, without overly affecting the flow elsewhere. The radial end face36is flush with the transverse longitudinal wall22of the plate16at the upstream longitudinal end of the fin34. This makes it possible to avoid having an “upward step” effect, which would be detrimental for the performance of the turbine engine. Furthermore, as can be seen inFIG.6, at the downstream longitudinal end of the fin34, i.e. at the downstream end of the fin (34), the radial end face36is curved to extend essentially radially and be flush with the peripheral wall20of the plate16. Thus, at each of the longitudinal ends thereof, the radial end face36is flush with, or extends from the transverse longitudinal wall22or the peripheral wall20of the plate16. There is then no disengagement between the radial end face36of the fin34and the transverse longitudinal wall22or the peripheral wall20of the plate16, which makes it possible to prevent the formation of additional vortices which could be detrimental to the performances of the vane14. In order to limit the disturbances in the air liable to be produced by a fin, the upstream longitudinal end of each fin34is longitudinally offset downstream in relation to the leading edge24of the blade12. Preferably, this longitudinal offset downstream is at least equal to 30% of the longitudinal length of the plate16. The zone located at the leading edge24of the blade12is a zone wherein the air flow is not completely oriented parallel with the vane. An aerodynamic blocking zone (with high Mach) can appear in the vicinity of the leading edge24for certain working points, therefore, projections should be avoided in this zone. As stated above, the vane14is movable in rotation in relation to the compressor stator about a radial axis. As the fins34are mounted on the plate16, the fins34are also movable in rotation integrally with the vane14, ensuring satisfactory rectification efficiency of the air flow in the compressor and the reduction of the disturbances32commonly referred to as “corner vortices”. According to a preferred embodiment, each fin34is made of one piece with the plate16which is associated therewith. This embodiment can be by moulding or any other embodiment, such as for example by additive technology. The description given above for one or two fins applies to the fins which are borne by the plate16located at the radially inner end of the blade12. It will be understood that this description will apply in the same way for each fin34which is borne by the plate18located at the radial outer end of the blade12. | 9,569 |
11859503 | DETAILED DESCRIPTION FIG.1illustrates an aircraft power plant comprising a nacelle N housing a gas turbine engine10of a type preferably provided for use in subsonic flight, and generally comprising in serial flow communication an air inlet11, a compressor12for pressurizing the air from the air inlet11, a combustor13in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, a turbine14for extracting energy from the combustion gases, and an exhaust case15through which the combustion gases exit the engine10. The turbine14includes a low pressure (LP) or power turbine14adrivingly connected to an input end of a fully enclosed reduction gearbox (RGB)16. The RGB16has an output end drivingly connected to an output shaft18configured to drive a rotatable load (not shown). For instance, the rotatable load can take the form of a propeller or a rotor, such as a helicopter main rotor. The gas turbine engine10has an engine centerline17. According to the illustrated embodiment, the compressor and the turbine rotors are mounted in-line for rotation about the engine centerline17. The gas turbine engine10has an axially extending central core which defines an annular gaspath20through which gases flow, as depicted by flow arrows inFIG.1. The exemplary embodiment shown inFIG.1is a “reverse-flow” engine because gases flow through the gaspath20from the air inlet11at a rear portion thereof, to the exhaust case15at a front portion thereof. According to one aspect, the engine10can have an engine architecture corresponding to that of the engine described in applicant's U.S. Pat. No. 10,393,027 issued on Aug. 27, 2019, the entire content of which is herein incorporated by reference. While the engine10is exemplified as a reverse flow engine, it is understood that the engine could be embodied as a through-flow engine. As shown inFIG.1, the exhaust case15may comprise an asymmetric dual port exhaust duct30for exhausting combustion gases received from the last stage of the LP turbine14aon opposed sides of the engine10. The dual port exhaust duct30is qualified as “asymmetric” because the two exhaust ports thereof are not coaxial to the engine centerline17(i.e. the exhaust flow discharged from the exhaust duct is not axial, it is rather discharged in a direction that diverges from the engine centerline17). According to at least some embodiments, the dual port exhaust duct30has a generally “Y-shaped” annular body including an annular central inlet conduit portion extending axially around the engine centerline17for receiving the annular flow of combustions gases discharged from the last stage of LP turbine14a, and first and second diverging outlet conduit portions30b,30cbranching off laterally from the central inlet conduit portion. According to some embodiments, the first and second outlet conduit portions30b,30care identical. Still referring toFIG.1, it can be seen that the turbine14comprises a power or LP turbine housing24mounted to and extending axially from the RGB16centrally into the hollow center of the annular exhaust duct30. The LP turbine housing24is configured to receive a bearing (not shown) for supporting the LP turbine rotor(s). During assembly, the exhaust duct30is axially slid in position over the LP turbine housing24. Once the exhaust duct30has been properly positioned over the LP turbine housing24, the two are detachably secured to the RGB16such as by bolting at a front flange interface. Still referring toFIG.1, it can be seen that the engine10has a cold section C. The cold section C includes the air inlet11and the compressor12. The engine10also has a hot section H, which in use, is subject to high temperatures. The hot section H includes the combustor13, the turbine14and the exhaust case15. For instance, the temperatures inside the turbine14are typically in excess of 1000 degree. C. In use, the continuous flow of gas to which the turbine14is exposed can be at temperatures up to 1700 degree. C. The engine10is equipped with a plurality of probes (sensors) for measuring various operating parameters, such as torque, speed, distance, temperature, pressure etc. Some of these probes are disposed in the hot section H of the engine10. Accordingly, these probes need to be able to cope with the high temperatures prevailing in the hot section H of the engine10. It may thus be desirable to thermally shield the probes in order to maintain the temperature of the probes within acceptable limits.FIGS.1-3illustrate an example of such a thermally shielded probe. More particularly,FIGS.1-3illustrate a probe22projecting through the exhaust case15and the LP turbine housing24to a location where a tip22aof the probe22is positioned adjacent to the LP turbine shaft14bfor measuring an operating parameter (e.g. speed and/or torque) of the LP turbine14a. The exemplary probe22extends through a probe boss32mounted in a receiving hole defined at the top dead center of the exhaust duct30between the two diverging outlet conduit portions30b,30cthereof. The term “boss” is herein intended to generally refer to a mounting feature on a work piece. For instance, it can take the form of a protruding feature used to locate one component (e.g. a probe) within a pocket or hole of another component (e.g. the exhaust duct). As exemplified inFIGS.2-3, the probe boss32may be provided in the form of a cylindrical sleeve32acast with an outer flange32bwelded or otherwise suitably secured to the exhaust duct30. According to some embodiments, the sleeve32ahas a slanted tubular portion that projects inwardly into the exhaust duct30in a “dead” air cavity34radially between the LP turbine housing24and the exhaust duct30. The slanted tubular portion is aligned with an associated probe boss36provided on the turbine housing24. The probe bosses32,36extend centrally around a common probe axis P. Such axially aligned probe bosses32,36provide a passage for the probe22through the exhaust case15and the turbine housing24. As shown inFIG.2, the probe22extends through the registering probe bosses32,36and into the LP turbine housing24next to the LP turbine shaft14b. The tip portion22aof the probe22is thermally shielded by the oil contained in the LP turbine housing24. However, the upper portion of the probe22in the cavity34between the exhaust duct30and the turbine housing24does not benefit from the heat shielding action of the oil in the turbine housing24. Accordingly, a probe heat shield is provided in the cavity34to protect the upper portion of the probe22from heat radiations emanating from the exhaust duct30. As will be seen hereinafter, the probe heat shield is configured to create a heat shielding volume around the probe22along a radial extent of the cavity34between the exhaust duct30and the LP turbine housing24while allowing for the assembly of the exhaust duct30over the LP turbine housing24. As shown inFIG.2, the probe heat shield may include a thermal blanket38mounted to a radially outer surface of the turbine housing24so as to cap or surround the probe boss36. The thermal blanket38can include a thermal insulation core (e.g. high temperature insulation fiber/wool materials) encapsulated in a metallic skin (e.g. sheet metal or metallic foil). The thermal blanket38forms a protective enclosure around a first portion of the length the probe projecting radially outwardly from the LP turbine probe boss36. However, as shown inFIG.2, the protective enclosure formed by the thermal blanket38on the LP turbine housing24only radially extends along a portion of the cavity34. Indeed, the radially outer end of the thermal blanket38through which the probe22extends is spaced radially inwardly from the inner end of the probe boss32on the exhaust duct30so as to permit axial assembly of the exhaust duct30over the LP turbine housing24along the engine centerline17. To further thermally shield the probe22from heat radiation in the cavity34, the heat shield further comprises a sleeve40, which bridges the space between the LP turbine housing24and the exhaust case15. As will be seen hereinafter, the sleeve40cooperates with sealing features and adjoining structures to create an annular “dead” air cavity42around the probe22. Referring toFIGS.2and4, it can be appreciated that the sleeve40has a radially inner end40afixedly mounted to the turbine housing24. More particularly, the radially inner end40aof the sleeve40is assembled on the probe boss36with a tight fit (also know as an interference fit). The radially inner end40aof the sleeve40has an inner diameter surface sized for a tight fit engagement with a corresponding outer diameter surface36aat a radially outer distal end of the probe boss36. As shown inFIG.4, the inner diameter surface of the sleeve40may include circumferentially spaced-apart tight fit contact surface segments44aspaced by inter-segment slots44bto provide a circumferentially discontinuous tight fit engagement of the sleeve40on the outer diameter surface36aof the probe boss36. Such a discontinuous or interrupted tight fit interface between the sleeve40and the probe boss36may be used to facilitate assembly and dis-assembly by reducing the assembly/dis-assembly loads required to assemble or dis-assemble the sleeve40. The sleeve assembly may be further facilitated by thermally expanding the sleeve40prior to the sleeve40being engaged over the probe boss36. Once in position, the sleeve40is allowed to cool down to create the interference fit with the probe boss36. According to such embodiments, the material of the sleeve40is selected to have substantially the same coefficient of thermal expansion as that of the probe boss36of the LP turbine housing24to preserve the integrity of the interference fit during engine operation. For instance, the LP turbine housing24and the sleeve40could be made from a nickel-based superalloy (e.g. Inconel 625). According to the embodiment illustrated inFIG.4, the inner diameter surface of the sleeve40has three tight fit contact surface segments44aand three inter-segment slots44b. However, it is understood that the number of tight fit contact surface segments44aand, thus, of inter-segment slots44bcan vary. For instance, only two tight fit contact surface segments44acould be provided. According to still further variants, the sleeve40could include more than three tight fit contact surface segments44a. According to the illustrated embodiment, the tight fit contact surface segments44aand the inter-segments slots44bhave a same circumferential length. However, it is understood that the circumferential length of the tight fit contact surface segments44acould be different from that of the inter-segment slots44b. Still referring toFIG.4, it can be further appreciated that the tight fit contact surface segments44aare equally circumferentially distributed around the radially inner end of the sleeve40to provide for a uniform circumferential engagement of the sleeve40on the probe boss36. According to some embodiments, the inter-segment slots44bmay be milled or otherwise suitably formed in the inner diameter surface of the radially inner end of the sleeve40. Alternatively, the tight fit contact surface segments44acould be formed by additive manufacturing or other suitable manufacturing processes. Referring back toFIG.2, it can be appreciated that the probe boss36has an annular outer shoulder36bprojecting from the outer diameter surface36a. The outer shoulder36bprovides an abutting surface (normal to the axis P) against which the radially inner end surface of the sleeve40is pushed in sealing abutment at assembly. In this way, the radially inner end40aof the sleeve40can be sealingly assembled onto the probe boss36even though the tight fit interface between the sleeve40and the probe boss36is not circumferentially continuous. Such a mounting arrangement of the sleeve40on the probe boss36allows to substantially sealingly close the radially inner end of the annular cavity42, thereby preventing hot air circulation therethrough. Still referring toFIG.2, the probe boss36further comprises an annular inner shoulder36cfor engagement with a corresponding annular outer shoulder22bon the probe22. The probe22is releasably secured in position against shoulder36cby a hollow bolt50threadably engageable with the probe boss36. As shown inFIG.2, the hollow bolt50is adapted to be slidably fitted over the upper end portion of the probe22and is provided at a distal end with outer threads50afor meshing engagement with corresponding inner threads36dformed in an inner diameter surface of the probe boss36above the shoulder36c. The hollow bolt50may have a hexagonal head50bopposite its externally threaded end portion for facilitating tightening of the bolt50into the probe boss36. Referring jointly toFIGS.2and3, it can be appreciated that the hollow bolt50has an annular outer shoulder50cat an upper end thereof axially adjacent to the hexagonal head50b. The shoulder50cis configured to axially compress a resilient or compressible-type seal, such as the exemplified C-ring seal52(herein after C-seal52), against an annular inner shoulder40cprojecting from an inner diameter surface of a radially outer end40bof the sleeve40. The C-seal52serves the dual purpose of: 1) sealing the radially outer end of the dead air cavity42and 2) urging/biasing the sleeve40in sealing contact against the outer shoulder36bon the probe boss36while accommodating thermal growth of the sleeve40during engine operation. The sleeve40is thus axially clamped between the outer shoulder50cof the bolt50and the outer shoulder36bof the probe boss36with a spring-loaded action provided by the C-seal52. The C-seal clamping assembly may be configured such that the C-seal52is compressed (and thus axially loads the sleeve40) at cold assembly condition (i.e. when the sleeve40is not subject to thermal growth). From the foregoing, it can be appreciated that the annular cavity42between the sleeve40and the hollow bolt50of the probe22is closed at both its radially inner and radially outer ends. The annular cavity42is thus a “dead” air cavity that operates as thermal insulation around the probe22. That is a cavity in which there is no air circulation. A pressure delta may also be used to prevent fluid flow (e.g. hot air) from entering the dead air cavity42. The compressible seal (e.g. the C-seal52) at the radially outer end of the sleeve40allows to accommodate the thermal expansion of the sleeve40relative to the bolt50as schematically depicted by arrows A inFIG.2while preserving the integrity of the dead air cavity42. It can be appreciated fromFIG.2that the sleeve40extends radially into the space thermally shielded by the thermal blanket38around the probe boss36. The radially outer end40bof the sleeve40is floatingly/movably received in the second probe boss32(i.e. the probe boss on the exhaust duct30) for relative movement with respect thereto in response to thermal growth. As best shown inFIG.3, the radially outer end40bof the sleeve40is spaced from a surrounding inner surface of the probe boss32by an annular control gap60. A compressible seal, such as a rope seal62, extends across the annular control gap60. The rope seal62may be removably mounted in an annular groove or any suitable seat defined in an outer diameter surface of the radially outer end40bof the sleeve40. The rope seal62is made out of a compressible material to provide sealing as well as damping between the sleeve40and the probe boss32of the exhaust case15. More particularly, the rope seal62prevents hot air leakage from cavity34into the air cavity G while limiting the transmission of vibrations between the sleeve40and the probe boss32. In addition, the rope seal62prevents water or sand/dirt particles from being ingested from cavity G into cavity34. The sleeve40is installed in position after the exhaust case15and the turbine housing24have been assembled together. The sleeve40is first thermally expanded and then installed over the first probe boss36via the second probe boss32. The sleeve40is pushed axially along axis P so as to sealingly abut the annular end face at the radially inner end40aof the sleeve40against the outer shoulder36bof the probe boss36. Then, the sleeve40is allowed to cool down to cause the tight fit contact surface segments44aon the inner diameter surface of the sleeve40to contract against the outer diameter surface36aof the probe boss36, thereby providing for an interference fit between the sleeve40and the probe boss36. The so created interference fit secures the sleeve40on the turbine housing24. The rope seal62is typically installed on the sleeve40prior to the sleeve40being inserted through the probe boss32. Then, the probe22is inserted through the probe bosses32,36and pushed axially in position so as to abut the probe outer shoulder22bagainst the corresponding inner shoulder36cof the probe boss36. Prior or after inserting the probe22, the C-seal52or an equivalent compression seal thereof is seated on the inner shoulder40cat the radially outer end40bof the sleeve40. Thereafter, the hollow bolt50is fitted over the probe22and tightened to the probe boss36in order to secure the probe22in position and to apply a clamping load against the sleeve40via the bolt outer shoulder50cand the C-seal52. The compression of the C-seal52between the sleeve40and the hollow bolt50allows to seal the radially outer end of the annular dead air cavity42. The radially inner end of the cavity42is sealed via the engagement of the end face of the radially inner end40aof the sleeve40and the opposing surface of the outer shoulder36bon the probe boss36. The biasing action of the C-seal52on the sleeve40contributes to ensure proper sealing contact between the radially inner end40aof the sleeve40and the outer shoulder36bof the probe boss36. It can be appreciated that the cavity42is closed at both ends thereof, thereby avoiding air recirculation or debris ingestion. The mounting arrangement thus provides for the creation of a dead air cavity as a means for thermally shielding the probe22from the heat radiated into the cavity34between the exhaust duct30and the turbine housing24during engine operation. The sleeve mounting arrangement provides a simple solution to thermally protect the probe22from heat radiation emanating from the exhaust duct30. To remove the sleeve40, the bolt50is first untightened and removed. Thereafter, the probe22is removed. Then, a suitable tool, such as a puller (not shown), is used to grab the sleeve40by its inner shoulder40cto pull the sleeve40out of engagement from the first probe boss36. The inner shoulder40cthus serves as a sealing surface and a pulling feature to remove the sleeve40when need be. The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. For instance, while the probe installation has been described in the context of a turboprop/turboshaft engine architecture, it is understood that it could be applied to other engines, including turbofan and auxiliary power unit (APU) engines. Also, while the exemplified probe is installed on the power turbine housing, it is understood that it could be installed on other structures of the hot section of an engine. Also, it is understood that the present disclosure is not limited to a specific type of probe, such as speed and torque probes. Other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims. | 19,726 |
11859504 | DETAILED DESCRIPTION OF INVENTION FIG.1shows an exemplary embodiment of a seal arrangement01according to the invention, wherein portions of a first housing part11(lower side) and a second housing part12(upper side) are shown with a respective flange12,22. The opposing flange faces here form the first end face13of the first housing part11and the second end face23of the second housing part21. The gap which must be sealed by means of the seal arrangement01is defined between the end faces. On one side of the gap or end faces13,23is the inside03, and opposite this the outside04. The seal arrangement01is effective in cases in which the media pressure on the inside03corresponds at least to the media pressure on the outside04. The seal arrangement01is advantageously shown in the detail view inFIG.2. This shows firstly the first receiving groove14in the first housing part11. Said groove14has a simple and advantageous rectangular design. The flank of the first receiving groove14pointing towards the outside04forms the first outer flank15. Opposite this in the second housing part21is the second receiving groove24, which also has a second outer flank25on the side pointing towards the outside04. The seal arrangement01here comprises firstly the sealing strip06achieving the seal, which extends along the receiving grooves14,24and transversely to the end faces13,23. It is clearly evident that here the sealing strip06has a particularly simple, flat form. The sealing strip06bears with one side edge on the first outer flank15and with the second side edge on the second outer flank25. The sealing effect is achieved firstly by the pressure difference between the inside03and the outside04. To guarantee an initial seal, in particular at low pressure differences, and in particular to secure the position of the sealing strip06during mounting, the seal arrangement01furthermore comprises a helical strip07extending along the first receiving groove14. Here, it is provided that the helical strip07is clamped under slight pressure in the first receiving groove14between an inner flank and the first outer flank15or the sealing strip06. This elastic deformation of the helical strip07here creates a radial force applied by the helical strip07on the sealing strip06, so that the latter is pressed onto the first outer flank15and the second outer flank25. Furthermore, the particularly advantageous design of the second outer flank25can be seen, which has a sloping course with respect to the first outer flank15. Here, an extension15aof the first outer flank15is shown. It is evident that an outer end26of the second outer flank25, at the second end face23, has a distance from the first end face15or its extension15a, and is thus arranged offset towards the outside04. In contrast, an inner end27of the second outer flank25, at the groove base of the second receiving groove24, is offset towards the inside03and arranged spaced from the extension15aof the first outer flank15. It is evident that when the second housing part21is joined to the first housing part11, this arcuate or sloping course of the second outer flank25, with the pre-mounted arrangement of the sealing strip06and helical strip07, leads to the sealing strip06being threaded into the second receiving groove24. Furthermore, it is evident that thanks to the sloping course, with the offset pointing towards the inside03above the middle of the second flank25, it can be guaranteed that in mounted state, the sealing strip06in any case bears reliably on the second outer flank25. An essential aspect for the particularly advantageous design is the sloping or arcuate course of the second outer flank25. For this,FIGS.3to5show further possible designs, each with respect to the extension15aof the first outer flank15.FIG.3shows the outer flank formed from two straight sloping portions, wherein the portion pointing towards the outer end26slopes more greatly than the portion pointing towards the inner end27.FIG.4shows the arcuate course of the second outer flank25′ starting from the middle towards the inner end27. In contrast,FIG.5shows an exemplary embodiment in which the second outer flank25″ has an arcuate course in its path towards the outer end26. | 4,229 |
11859505 | DESCRIPTION OF EMBODIMENTS Configuration of Steam Turbine Hereinafter, a steam turbine100according to an embodiment of the present disclosure will be described with reference toFIGS.1to5. As shown inFIGS.1and2, the steam turbine100includes a steam turbine rotor1, a bearing2, a steam turbine casing3, a casing support unit4, a first heating unit5, a second heating unit6, a temperature detection system T, a clearance detection unit7, and a control device90. The steam turbine rotor1has a columnar shape extending in a direction of an axis Ax and is supported by a bearing2in a state of being rotatable around the axis Ax. As shown inFIG.2, the steam turbine rotor1has a columnar rotor body1S extending along the axis Ax and a rotor blade stage1B provided on an outer peripheral surface of the rotor body1S. In addition,FIG.2schematically shows only the outer shape of the rotor blade stage1E. A plurality of the rotor blade stages1B are arranged at intervals in the direction of the axis Ax on the outer peripheral surface of the rotor body1S. One bearing2is provided at each of both end portions of the steam turbine rotor1. As shown inFIG.2, the bearings2are radial bearings that support a radial load exerted by the rotor body1S. The bearing2has a bearing body2H and a bearing support member2S that supports the bearing body2H. An end portion of the rotor body1S is inserted through the bearing body2H. In addition, although not shown in detail, in addition to the bearing2serving as a radial bearing, it is also possible to provide a thrust bearing that supports a load in the direction of the axis Ax. Additionally, inFIG.2, the illustration of the above-mentioned casing support unit4is omitted. The steam turbine casing3surrounds a portion of the steam turbine rotor1between the bearings2from an outer peripheral side. The steam turbine casing3has an upper half casing31and a lower half casing32joined together in an up-and-down direction, and a stationary blade stage31S. The upper half casing31has a semi-cylindrical shape centered on the axis Ax and has an upper half casing body31H that opens downward and an upper half flange31F (flange) that is integrally provided in the upper half casing body31H. The upper half flange31F protrudes in a plate shape from the edge of an opening portion of the upper half casing body31H toward the outside in the horizontal plane. The upper half flange31F is provided with a support portion Sp for supporting the upper half flange31F on the casing support unit4, which will be described below. Similarly, the lower half casing32has a semi-cylindrical shape centered on the axis Ax and has a lower half casing body32H that opens upward and a lower half flange32F (flange) that is integrally provided in the lower half casing body32H. The lower half flange32F protrudes in a plate shape from the edge of an opening portion of the lower half casing body32H toward the outside In the horizontal plane. The lower half flange32F is provided with a support portion Sp for supporting the lower half flange32F on the casing support unit4, which will be described below. The steam turbine casing3is formed by causing the upper half flange31F and the lower half flange32F to abut against each other from the up-and-down direction. A space that accommodates the above-mentioned steam turbine rotor1is formed inside the steam turbine casing3. As shown inFIG.2, an inner peripheral surface of the upper half casing31and an inner peripheral surface of the lower half casing32are provided with the stationary blade stage31S that protrudes toward the inside of the space. Although not shown in detail, a plurality of the stationary blade stages31S are arranged alternately with the rotor blade stages1B of the steam turbine rotor1in the direction of the axis Ax. Additionally, the steam turbine casing3is provided with an intake hole3H for guiding steam from the outside and an exhaust hole3E for discharging steam to the outside. The steam turbine casing3configured in this way is supported from below on a stand40by the casing support unit4. One casing support unit4is provided on each side of the steam turbine casing3in the direction of the axis Ax. The stand40is formed with an opening portion40H that is recessed downward, and most of the lower half casing32of the steam turbine casing3is buried in the opening portion40H. The casing support unit4is provided with a first heating unit3for heating the casing support unit4. Specifically, as the first heating unit5, an electric heater that generates heat because of internal resistance when an electric current is passed is suitably used. Moreover, the above-mentioned upper half flange31F and lower half flange32F are each provided with a second heating unit6. The second heating unit6heats the upper half flange31F and the lower half flange32F. The second heating unit6is provided on each of side surfaces (that is, surfaces facing a horizontal direction) of the upper half flange31F and the lower half flange32F. Specifically, as the second heating unit6, an electric heater similar to that of the first heating unit3is suitably used. The temperature detection system T that detects the temperature of each member is provided in the bearing2, the upper half casing body31H, the upper half flange31F, the lower half flange32F, the casing support unit4, and the support portion Sp. Specifically, the temperature detection system T includes a bearing temperature detection unit2T provided on the bearing2(bearing support member2S), an upper half flange temperature detection unit31T provided on the upper half flange31F, a lower half flange temperature detection unit32T provided on the lower half flange32F, a casing temperature detection unit4T provided in the casing support unit4, an upper half casing temperature detection unit HT provided in the upper half casing body31H, and a support portion temperature detection unit ST provided in the support portion. The temperature detection system T detects the temperature of an object and inputs the defection value to a control device90to be described below as an electric signal. That is, the temperature detection system T is electrically connected to the control device90by a signal line (not shown) or a wireless line. Moreover, as shown inFIG.2, the clearance detection unit7that detects the clearance between the steam turbine rotor1and the steam turbine casing3is provided in the steam turbine casing3. More specifically, the clearance detection unit7detects the magnitude of the clearance between a tip of the rotor blade stage1B and an inner peripheral surface of the steam turbine casing3. The magnitude of the clearance detected by the clearance detection unit7is input to the control device90as an electric signal. (Configuration of Control Device) The control device90switches the operating states of the first heating unit5and the second heating unit6on the basis of the respective detection values input from the above-mentioned temperature detection system T and clearance detection unit7. The operation of the first heating unit5and the second heating unit6can be switched between art ON state in which heating is possible by supplying an electric current and an OFF state in which heating is not possible by interrupting the electric current. The control device90performs switching between the ON state and the OFF state on the basis of each detection value. As shown inFIG.3, the control device90is a computer including a central processing unit (CPU)91, a read only memory (ROM)92, a random access memory (RAM)93, a hard disk, drive (HDD)94, and a signal receiving module95(I/O: Input/Output). The signal receiving module95receives electric signals from the temperature detection system T and the clearance detection unit7. The signal receiving module95may receive an amplified signal via, for example, a charge amplifier or the like. Moreover, as shown inFIG.4, the CPU91of the control device90functions as a control unit81, a storage unit82, a determination unit83, an input unit84, and a heating control unit85by executing a program stored in the CPU91in advance. The control unit81controls other functional units provided in the control device90. The storage unit82stores the target temperature of the casing support unit A when heated by the first heating unit5. Moreover, the storage unit82stores the target temperatures of the upper half flange31F and the lower half flange32F when the flanges are heated by the second heating unit6. In addition, the storage unit82stores a target value of the magnitude of the clearance between the steam turbine casing3and the steam turbine rotor1. The determination unit83determines the magnitude of respective detection values of the temperature detection system T and the clearance detection unit7that have been received via the input unit84, and respective target values, in a case where the determination unit83determines that each detection value is smaller than each target value, the heating control unit85turns on at least one of the first heating unit5and the second heating unit6. Accordingly, at least one of the casing support unit4and the steam turbine casing3is heated to cause thermal extension. More specifically, when the casing support unit4is heated by the first heating unit5, the steam turbine casing3expands in the up-and-down direction because of the thermal extension. When the upper half flange31F and the lower half flange32F are heated by the second heating unit6, the steam turbine casing3expands in the direction of the axis Ax. By combining these phenomena, the clearance between the steam turbine casing3and the steam turbine rotor1is adjusted. On the other hand, in a case where the determination unit83determines that each detection value is larger than each target value, the heating control unit85turns off at least one of the first heating unit5and the second heating unit6. Accordingly, at least one of the casing support unit4and the steam turbine casing3is eliminated from the thermal extension, which has occurred so far, and contracts. More specifically, when the heating of the casing support unit4by the first heating unit5is stopped, the steam turbine casing3contracts in the up-and-down direction because of the elimination of the thermal extension. When the heating of the upper half flange31F and the lower half flange32F by the second heating unit6is stopped, the steam turbine casing3contracts in the direction of the axis Ax. By combining these phenomena, the clearance between the steam turbine casing3and the steam turbine rotor1is adjusted. In addition, it is desirable that the temperature detection of each part by the temperature detection system T is performed in preference to the clearance detection by the clearance detection unit7. This is because, in general, a temperature sensor used as the temperature detection system7has higher durability than a non-contact type distance measuring sensor used as the clearance detection unit7. That is, by simultaneously detecting the temperature via the temperature detection system T, the redundancy and fail-safe performance can be enhanced as compared to, for example, a case where the clearance is adjusted only by the clearance detection unit7. Subsequently, in the operation of the control device90, particularly the operation when the steam turbine100is started will be described with reference toFIG.5. As shown in the figure, in this control flew, the operating states of the first heating unit5and the second heating unit6are switched on the basis of the load of the steam turbine100. First, the control device90turns on the first heating unit5and the second heating unit6prior to the start of the steam turbine100(prior to the start) (Steps S11and S12). Accordingly, the thermal extension (expansion) occurs in the up-and-down direction and the direction of the axis Ax in the steam turbine casing3. That is, prior to the start of the steam turbine100, the above-mentioned clearance is increased. After that, the steam turbine100is started. Simultaneously with the start cf the steam turbine100, the control device90turns off the first heating unit5(Step S2). The second heating unit6maintains the ON state. Subsequently, when the detection value by the temperature detection system T or the detection value by the clearance detection unit7reaches a predetermined target value (temperature target value or clearance target value) (Step S31, Step S32: Yes), the control device90turns on the first heating unit5again (Step S41) and turns off the second heating unit6(Step S42). After that, when the detection value by the temperature detection system T or the detection value by the clearance detection unit7reaches a predetermined target value (temperature target value or clearance target value) again (Step S51: Yes), the control device90turns off the first heating unit5again (Step S52). Accordingly, the start of the steam turbine100is completed. (Working Effects) When the steam turbine100is started, the steam turbine rotor1is slightly displaced upward by the thermal extension earlier than the steam turbine casing3on the basis of a difference in thermal capacity. Because of this displacement, there is a possibility that the clearance between the steam turbine rotor1and the steam turbine casing3becomes excessively small. However, in the above configuration, the thermal extension can be caused in the steam turbine casing3by heating the casing support unit4with the first heating unit5. Accordingly, the above clearance can be maintained. In particular, there is a case where the thermal extension in the direction of the axis Ax occurs in the steam turbine rotor1. According to the above configuration, even in a case where the thermal extension in the direction of the axis Ax has occurred, the thermal extension in the direction of the axis Ax can also be caused in the steam turbine casing3by heating the flanges (the upper half flange31F and the lower half flange32F) with the second heating unit6. Accordingly, the relative position between the steam turbine rotor1and the steam turbine casing3in the direction of the axis Ax can be maintained. Moreover, according to the above configuration, the ON state and the OFF state of the first heating unit5and the second heating unit6can be switched on the basis of the temperature of each part detected by the temperature detection system T. Accordingly, the first heating unit5and the second heating unit6can be appropriately operated depending on the operating state of the steam turbine100. Additionally, after the start of the steam turbine100, first, the steam turbine rotor1thermally extends more than the steam turbine casing3. Therefore, it is desirable to cause the thermal extension in the steam turbine casing3in advance by turning on the first heating unit3before the start of the steam turbine100. Accordingly, the clearance can be maintained. On the other hand, during a certain period immediately after starting the steam turbine100, the thermal extension of the steam turbine casing3may exceed the thermal extension of the steam turbine rotor1. Therefore, by turning off the first heating unit5simultaneously with the start of the steam turbine100as in the above configuration, it is possible to suppress excessive thermal extension of the steam turbine casing3. Moreover, when the casing temperature has changed because of the rapid inflow of high-temperature steam into the turbine casing, the steam turbine rotor1is in a state of having thermally extended more than the steam turbine casing3. Therefore, as in the above configuration, when the temperature detection value or the clearance detection value has reached the target value, the first heating unit5can be turned on again to minimize the difference in thermal extension between the steam turbine rotor1and the steam turbine casing3. Additionally, according to the above configuration, by turning on the second heating unit6before the start of the steam turbine100, the steam turbine casing3can be caused to thermally extend in advance in the direction of the axis Ax. Accordingly, the relative position between the steam turbine rotor1and the steam turbine casing3after the start can be maintained in the direction of the axis Ax. Here, the magnitude of the thermal extension in the up-and-down direction occurring in the bearing2is proportional to the temperature of the bearing2. According to the above configuration, by detecting the temperature of the bearing2with the bearing temperature detection unit2T, it is possible to know the displacement caused by the thermal extension that has occurred in the bearing2. Moreover, the magnitude of the thermal extension in the up-and-down direction occurring in the casing support unit4is proportional to the temperature of the casing support unit4. According to the above configuration, by detecting the temperature of the casing support, unit4with the casing temperature detection unit4T, it is possible to know the displacement caused by the thermal extension that has occurred in the casing support unit4. In addition, the magnitude of the thermal extension in the direction of the axis Ax occurring in the steam turbine casing3is proportional to the temperature of the flange. According to the above configuration, by detecting the temperature of the flange with the flange temperature detection units31T and32T, it is possible to know the displacement because of the thermal extension in the direction of the axis Ax that has occurred in the steam turbine casing3. Furthermore, according to the above configuration, by switching the ON state and the OFF state of the first heating unit5on the basis of the magnitude of the clearance, the clearance between the steam turbine rotor1and the steam turbine casing3can be more actively optimized. Other Embodiments The embodiment of the present disclosure has been described in detail above with reference to the drawings. However, the specific configuration is not limited to the embodiment, and includes design changes or the like without departing from the gist of the present disclosure. <Additional Notes> The steam turbines described in the respective embodiments are understood as follows, for example. (1) A steam turbine100according to a first, aspect includes a steam turbine rotor1that extends in a direction of an axis Ax, a pair of bearings2that rotatably support the steam turbine rotor1around the axis Ax, a steam turbine casing3that surrounds the steam turbine rotor1between the pair of bearings2, a casing support unit4that supports the steam turbine casing3from below, and a first heating unit5that is provided in the casing support unit4and that is capable of heating the casing support unit4. When the steam turbine100is started, the steam turbine rotor1is slightly displaced upward by the thermal extension earlier than the steam turbine casing3on the basis of a difference in thermal capacity. Because of this displacement, there is a possibility that the clearance between the steam turbine rotor1and the steam turbine casing3becomes excessively small. However, in the above configuration, the thermal extension can be caused in the steam turbine casing3by heating the casing support unit4with the first heating unit5. Accordingly, the above clearance can be maintained. (2) In the steam turbine100according to a second aspect, the steam turbine casing3has an upper half casing31and a lower half casing32that are joined together by combining flanges31F and32F thereof with each other, and the steam turbine further includes a second heating unit6that is fixed to side surfaces of the flanges31F and32F of the upper half casing31and the lower half casing32and that is capable of heating the flanges31F and32F. When the steam turbine100is started, the steam turbine rotor1thermally extends earlier than the steam turbine casing3on the basis of the difference in thermal capacity. In particular, there is a case where the thermal extension in the direction of the axis Ax occurs in the steam turbine rotor1. According no the above configuration, even in a case where the thermal extension in the direction of the axis Ax has occurred, the thermal extension in the direction of the axis Ax can also be caused in the steam turbine casing3by heating the flanges31F and32F with the second heating unit6. Accordingly, the relative position between the steam turbine rotor1and the steam turbine casing3in the direction of the axis Ax can be maintained. (3) The steam turbine100according to a third aspect further includes a temperature detection system T that detects the temperature of at least one of the bearing2, the flanges31F and32F, and the casing support unit4, and a control device90that performs switching between an ON state and an OFF state of the first heating unit5and the second heating unit6on the basis of a detection result of the temperature detection system T. According to the above configuration, the ON state and the OFF state of the first heating unit5and the second heating unit6can be switched on the basis of the temperature of each part detected by the temperature detection system T. Accordingly, the first heating unit5and the second heating unit6can be appropriately operated depending on the operating state of the steam turbine100. (4) In the steam turbine100according to a fourth aspect, the control device90turns on the first heating unit5before the start of the steam turbine100, turns off the first heating unit5when the steam turbine100is started, and turns on the first heating unit5again when the detection result of the temperature detection system T has reached a predetermined target value. After the start of the steam turbine100, first, the steam turbine rotor1thermally extends more than the steam turbine casing3. Therefore, it is desirable to cause the thermal extension in the steam turbine casing3in advance by turning on the first heating unit5before the start of the steam turbine100. Accordingly, the clearance can be maintained. On the other hand, during a certain period immediately after starting the steam turbine100, the thermal extension of the steam turbine casing3may exceed the thermal extension of the steam turbine rotor1. Therefore, by turning off the first heating unit5when the steam turbine100is started as in the above configuration, it is possible to suppress excessive thermal extension of the steam turbine casing3. Moreover, when the detection result of the temperature detection system T has reached the predetermined target value, the steam turbine rotor1is in a state of having thermally extended more than the steam turbine casing3. Therefore, as in the above configuration, when the load of the steam turbine100has reached 100%, the first heating unit5can be turned on again to minimize the difference in thermal extension between the steam turbine rotor1and the steam turbine casing3. (5) In the steam turbine100according to a fifth aspect, the control device90turns on the second heating unit6before the start of the steam turbine100to cause the steam turbine casing3to thermally extend in advance in the direction of the axis Ax. According to the above configuration, by turning on the second heating unit6before the start of the steam turbine100, the steam turbine casing3can be caused to thermally extend in advance in the direction of the axis Ax. Accordingly, the relative position between the steam turbine rotor1and the steam turbine casing3after the start can be maintained in the direction of the axis Ax. (6) In the steam turbine100according to a sixth aspect, the temperature detection system T has a bearing temperature detection unit2T that detects the temperature of the bearing2. The magnitude of the thermal extension in the up-and-down direction occurring in the bearing2is proportional to the temperature of the bearing2. According to the above configuration, by detecting the temperature of the bearing2with the bearing temperature detection unit2T, it is possible to know the displacement caused by the thermal extension that has occurred in the bearing2. (7) In the steam turbine100according to a seventh aspect, the temperature detection system T has a casing temperature detection unit4T that detects the temperature of the casing support unit4. The magnitude of the thermal extension in the up-and-down direction occurring in the casing support unit4is proportional to the temperature of the casing support unit4. According to the above configuration, by detecting the temperature of the casing support unit4with the casing temperature detection unit4T, it is possible to know the displacement caused by the thermal extension that has occurred in the casing support unit4. (8) In the steam turbine100according to an eighth aspect, the temperature detection system T has flange temperature detection units31T and32T that detect, the temperatures of the flanges31F and32F. The magnitude of the thermal extension in the direction of the axis Ax occurring in the steam turbine casing3is proportional to the temperatures of the flanges31F and32F. According to the above configuration, by detecting the temperatures of the flanges31F and32F with the flange temperature detection units31T and32T, it is possible to know the displacement caused by the thermal extension in the direction of the axis Ax that has occurred in the steam turbine casing3. (9) The steam turbine100according to a ninth aspect further includes a clearance detection unit7that detects a clearance between the steam turbine rotor1and the steam turbine casing3, and the control device90performs switching between an ON state and an OFF state of the first heating unit5when the clearance detected by the clearance detection unit7has reached a predetermined clearance target value. According to the above configuration, by switching the ON state and the OFF state of the first heating unit5on the basis of the magnitude of the clearance, the clearance between the steam turbine rotor1and the steam turbine casing3can be more actively optimized. (10) A steam turbine100according to a tenth aspect includes a steam turbine rotor1that extends in a direction of an axis Ax, a pair of bearings2that rotatably support the steam, turbine rotor1around the axis Ax, a steam turbine casing3that surrounds the steam turbine rotor1between the pair of bearings2, and a casing support unit. A that supports the steam turbine casing3from below, and the steam turbine casing3has an upper half casing31and a lower half casing32that are joined together by combining flanges31F and32F thereof with each other, and the steam turbine further includes a second heating unit6that is fixed to side surfaces of the flanges31F and32F of the upper half casing31and the lower half casing32and that is capable of heating the flanges31F and32F. When the steam turbine100is started, the steam turbine rotor1thermally extends earlier than the steam turbine casing3on the basis of the difference in thermal capacity. In particular, there is a case where the thermal extension in the direction of the axis Ax occurs in the steam turbine rotor1. According to the above configuration, even in a case where the thermal extension in the direction of the axis Ax has occurred, the thermal extension in the direction of the axis Ax can also be caused in the steam turbine casing3by heating the flanges31F and32F with the second heating unit6. Accordingly, the relative position between the steam turbine rotor1and the steam turbine casing3in the direction of the axis Ax can be maintained. REFERENCE SIGNS LIST 100steam turbine1steam turbine rotor1B rotor blade stage1S rotor body2bearing2H bearing body2S bearing support member3steam turbine casing3E exhaust hole3H intake hole31upper half casing32F upper half flange31H upper half casing body31S stationary blade stage32lower half casing32F lower half flange32H lower half casing body31T upper half flange temperature detection unit32T lower half flange temperature detection unit4casing support unit4T casing temperature detection unit5first heating unit6second heating unit7clearance detection unit81control unit82storage unit83determination unit84input unit85heat control unit90control device91CPU92ROM93RAM94HDD95signal receiving module (I/O) | 28,346 |
11859506 | DETAILED DESCRIPTION FIG.1schematically illustrates a propulsion system10for an aircraft. This aircraft propulsion system10includes a gas turbine engine12and an engine pylon14(or other structure) for mounting the gas turbine engine12to another component16of the aircraft such as, but not limited to, an aircraft wing or an aircraft fuselage. The gas turbine engine12may be a turbofan gas turbine engine, a turbojet gas turbine engine, a turboprop gas turbine engine, or any other type of gas turbine engine capable of producing thrust. The gas turbine engine12ofFIG.1, for example, includes a propulsor18and a gas turbine engine core20configured to drive the propulsor18. The propulsor18may be configured as or otherwise include a bladed propulsor rotor22of the gas turbine engine12. Examples of the propulsor rotor22include, but are not limited to: a fan rotor for the turbofan gas turbine engine; a compressor rotor for the turbojet gas turbine engine; and a propeller rotor for the turboprop gas turbine engine. The engine core20ofFIG.1includes one or more rotating structures24A and24B (generally referred to as “24”) (e.g., spools) and a stationary structure26. The engine core20ofFIG.1also includes a plurality of bearings28rotatably supporting the rotating structures24and mounting the rotating structures24to the stationary structure26. The first (e.g., low speed) rotating structure24A includes a first (e.g., low pressure (LP)) compressor rotor30A, a first (e.g., low pressure) turbine rotor32A and a first (e.g., low speed) shaft34A. The first compressor rotor30A is arranged within and part of a first (e.g., low pressure) compressor section36A of the engine core20. The first turbine rotor32A is arranged within and part of a first (e.g., low pressure) turbine section38A of the engine core20. The first shaft34A extends axially along a rotational axis40between and is connected to the first compressor rotor30A and the first turbine rotor32A, where the first rotating structure24A is rotatable about the rotational axis40. The first rotating structure24A may also be rotatably coupled to the propulsor18and its rotor22. The propulsor rotor22, for example, may be coupled to the first rotating structure24A through a direct drive coupling. This direct drive coupling may be configured as or otherwise include an output shaft42. With such a direct drive coupling, the propulsor rotor22and the first rotating structure24A may rotate at a common (e.g., the same) rotational speed. Alternatively, the propulsor rotor22may be coupled to the first rotating structure24A through a geartrain44(see dashed line); e.g., a transmission. This geartrain44may be configured as an epicyclic geartrain. With such a geared coupling, the propulsor rotor22may rotate at a different (e.g., slower) rotational speed than the first rotating structure24A. The second (e.g., high speed) rotating structure24B includes a second (e.g., high pressure (HP)) compressor rotor30B, a second (e.g., high pressure) turbine rotor32B and a second (e.g., high speed) shaft34B. The second compressor rotor30B is arranged within and part of a second (e.g., high pressure) compressor section36B of the engine core20. The second turbine rotor32B is arranged within and part of a second (e.g., high pressure) turbine section38B of the engine core20. The second shaft34B extends axially along the rotational axis40between and is connected to the second compressor rotor30B and the second turbine rotor32B, where the second rotating structure24B is rotatable about the rotational axis40. The second rotating structure24B ofFIG.1and its second shaft34B axially overlap and circumscribe the first shaft34A; however, the engine core20of the present disclosure is not limited to such an exemplary arrangement. The stationary structure26includes an engine case46; e.g., a core case. This engine case46is configured to at least partially or completely house the first compressor section36A, the second compressor section36B, a combustor section48of the engine core20, the second turbine section38B and the first turbine section38A, where the engine sections36A,36B,48,38B and38A may be arranged sequentially along the rotational axis40between an airflow inlet to the gas turbine engine12and an exhaust from the gas turbine engine12. The engine case46ofFIG.1axially overlaps and extends circumferentially about (e.g., completely around) the first rotating structure24A and the second rotating structure24B. The engine case46may include a plurality of discrete axial and/or circumferential sections (e.g., tubular and/or arcuate subcases), which discrete case sections are attached together to form the engine case46. During operation, air enters the gas turbine engine12through the airflow inlet. This air is directed into at least a core flowpath which extends sequentially through the engine sections36A,36B,48,38B and38A (e.g., the engine core20) to the exhaust. The air within this core flowpath may be referred to as “core air”. The core air is compressed by the first compressor rotor30A and the second compressor rotor30B and directed into a combustion chamber50of a combustor in the combustor section48. Fuel is injected into the combustion chamber50and mixed with the compressed core air to provide a fuel-air mixture. This fuel-air mixture is ignited and combustion products thereof flow through and sequentially cause the second turbine rotor32B and the first turbine rotor32A to rotate. The rotation of the second turbine rotor32B and the first turbine rotor32A respectively drive rotation of the second compressor rotor30B and the first compressor rotor30A and, thus, compression of the air received from the airflow inlet. The rotation of the first turbine rotor32A ofFIG.1also drives rotation of the propulsor rotor22. The propulsor rotor22may propel air through or outside of the gas turbine engine12to provide, for example, a majority of aircraft propulsion system thrust. FIG.2illustrates a structure52for the gas turbine engine12ofFIG.1. This structure52includes the engine case46, the engine pylon14and an engine line54. The engine case46includes an engine case base56and an engine case mounting structure58, which mounting structure58includes a pylon mounting boss60and one or more mounting boss support elements62A-D (generally referred to as “62”); see alsoFIGS.3-5. Referring toFIG.3, the base56extends axially along an axial centerline64of the engine case46and/or the gas turbine engine12, which axial centerline64may be coaxial with the rotational axis40. Referring toFIGS.4and5, the base56extends radially between and to an inner side66of the base56and an outer side68of the base56. The base56extends circumferentially about the axial centerline64. The base56, for example, may extend completely around the axial centerline64, thereby providing the base56and a respective section of the engine case46with a tubular body. The base56may alternatively extend partially (e.g., halfway) around the axial centerline64, thereby providing the base56and a respective section of the engine case46with an arcuate (e.g., half shell) body. The mounting boss60is connected to the base56at (e.g., on, adjacent or proximate) the base outer side68. The mounting boss60ofFIGS.4and5, for example, projects radially out from the base56to a distal radial outer side70of the mounting boss60. Referring toFIG.3, the mounting boss60extends laterally (e.g., circumferentially about the axial centerline64, tangentially to the base outer side68, etc.) between and to a lateral (e.g., circumferential) first side72of the mounting boss60and a lateral (e.g., circumferential) second side74of the mounting boss60. The mounting boss60extends axially along the axial centerline64between and to an axial first side76of the mounting boss60and an axial second side78of the mounting boss60. The mounting boss60may form at least a lateral intermediate portion of a first side surface80of the mounting structure58at the mounting boss axial first side76. The mounting boss60may form at least a lateral intermediate portion of a second side surface82of the mounting structure58at the mounting boss axial second side78. One or each of these mounting structure side surfaces80and82may each be configured as a flat, planar surface. The mounting boss60includes a radial outer surface84(e.g., a pylon land) and one or more mounting apertures86; e.g., threaded bolt holes. The mounting boss outer surface84is disposed at the mounting boss outer side70. This mounting boss outer surface84may be configured as a flat, planar surface; see alsoFIGS.4and5. The mounting boss outer surface84may extend axially between the mounting structure first side surface80and the mounting structure second side surface82. The mounting boss outer surface84ofFIG.3, for example, is contiguous with each mounting structure side surface80,82. The mounting boss outer surface84may meet each mounting structure side surface80,82at a (e.g., ˜90°) respective sharp corner, or alternatively at a rounded and/or otherwise eased corner. Referring toFIGS.4and5, each mounting aperture86projects radially into the mounting boss60from the mounting boss outer surface84. Each mounting aperture86may extend partially into the engine case46; e.g., each mounting aperture86may be a blind (e.g., dead end) aperture. One or more or all of the mounting apertures86may alternatively extend radially through the engine case46; e.g., each mounting aperture86may be a through-hole. Each of the mounting apertures86ofFIG.3is arranged at a respective corner of the mounting boss outer surface84; however, the present disclosure is not limited to such an exemplary arrangement/aperture pattern. The support elements62are configured to structurally reinforce the connection between the mounting boss60and the base56. Each support element62, for example, provides a material extension spanning between the mounting boss60and the base56. For example, each support element62may functionally be configured as a support leg and/or a gusset. The support elements62may thereby disperse loads across a larger swath of area along the base56than the mounting boss60alone. The support elements62may also reduce a load concentration and/or stress concentration at an interface (e.g., joint) between the mounting boss60and the base56. With such an arrangement, the support elements62may functionally increase the size of the mounting boss60without requiring additional material; e.g., if the mounting boss60was alternatively resized to be the same overall axial and lateral size of the entire mounting structure58. Each of the support elements62is connected to the base56at the base outer side68. Each support element62ofFIGS.4and5, for example, projects radially out from the base56to a distal radial outer side87A-D (generally referred to as “87”) of the respective support element62A-D. Each support element62is also connected to the mounting boss60at a respective one of the mounting boss lateral sides72,74. Each support element62ofFIGS.3-5, for example, projects laterally (e.g., circumferentially about the axial centerline64, tangentially to the base outer side68, etc.) out from the mounting boss60to a lateral (e.g., circumferential) distal end88A-D (generally referred to as “88”) of the respective support element62. Each support element62ofFIG.3extends axially along the axial centerline64between and to an axial exterior side90A-D (generally referred to as “90”) of the respective support element62and an axial interior side92A-D (generally referred to as “92”) of the respective support element62. The exterior sides90A and90B of the support elements62A and62B ofFIG.3respectively form opposing side portions of the mounting structure first side surface80. The exterior sides90C and90D of the support elements62C and62D ofFIG.3respectively form opposing side portions of the mounting structure second side surface82. Of course, in other embodiments, one or more or all of the exterior sides90A and/or90B,90C and/or90D may each be axially offset (e.g., spaced from) from the respective mounting boss axial side76,78. The mounting boss60is disposed laterally between the first side support elements62A and62C and the second side support elements62B and62D. The first side support elements62A and62C are thereby laterally offset and spaced from the second side support elements62B and62D. The support elements62A and62B at the mounting boss axial first side76may be axially aligned; e.g., axially overlap. The support elements62C and62D at the mounting boss axial second side78may be axially aligned; e.g., axially overlap. However, the first side support elements62A and62C ofFIG.3are axially offset and spaced from one another. The first side support elements62A and62C ofFIG.3, for example, are axially separated by a first side channel94A in the engine case46and its mounting structure58. The second side support elements62B and62D ofFIG.3are similarly axially offset and spaced from one another. The second side support elements62B and62D ofFIG.3, for example, are axially separated by a second side channel94B in the engine case46and its mounting structure58. With the foregoing arrangement, each boss support element62A-D may be arranged at a respective corner of the mounting boss60and its outer surface84; however, the present disclosure is not limited to such an exemplary arrangement/aperture pattern. The first side channel94A extends axially within the engine case46and, more particularly, the mounting structure58between and to the interior sides92A and92C of the first side support elements62A and62C. The first side channel94A extends laterally into the engine case46and, more particularly, the mounting structure58from the support element distal ends88A and88C to the mounting boss60at its lateral first side72. The first side channel94A extends radially inward into the engine case46and through the mounting structure58from the outer sides70,87A and87C to the base56at its outer side68. The second side channel94B extends axially within the engine case46and, more particularly, the mounting structure58between and to the interior sides92B and92D of the second side support elements62B and62D. The second side channel94B extends laterally into the engine case46and, more particularly, the mounting structure58from the support element distal ends88B and88D to the mounting boss60at its lateral second side74. The second side channel94B extends radially inward into the engine case46and through the mounting structure58from the outer sides70,87B and87D to the base56at its outer side68. At least one of the support elements (e.g.,62A) may be configured as or otherwise include a peripheral boss96; e.g., a mounting boss for the engine line54ofFIG.2. The support element62A ofFIG.4, for example, includes a peripheral boss outer surface98(e.g., an engine line coupler land) and an engine line aperture100. This support element62A may also include one or more mounting apertures102; e.g., threaded bolt holes. The peripheral boss outer surface98is disposed at the outer side87A of the support element62A. This peripheral boss outer surface98may be configured as a flat, planar surface. The peripheral boss outer surface98may extend laterally to the mounting boss outer surface84. The peripheral boss outer surface98ofFIG.4, for example, is contiguous with the mounting boss outer surface84. The peripheral boss outer surface98may meet the mounting boss outer surface84at a relatively sharp corner, or alternatively at a rounded and/or otherwise eased corner. The peripheral boss outer surface98is angularly offset from the mounting boss outer surface84by an included angle104A; e.g., an obtuse angle. This included angle104A may be greater than one-hundred and thirty-five degrees (135°) and less than one-hundred and eighty degrees (180°); e.g., between one hundred and forty degrees (140°) and one hundred and fifty-five degrees (155°), between one hundred and forty-five degrees (145°) and one hundred and fifty degrees (150°), etc. The present disclosure, however, is not limited to the foregoing exemplary positional relationship between the peripheral boss outer surface98and the mounting boss outer surface84. For example, the included angle104A may alternatively be less than one-hundred and thirty-five degrees (135°). In another example, the peripheral boss outer surface98and the mounting boss outer surface84may be parallel; e.g., coplanar. The peripheral boss outer surface98ofFIG.3may extend axially between the exterior side90A and the interior side92A of the support element62A. The peripheral boss outer surface98ofFIG.3is contiguous with the mounting structure first side surface80. The peripheral boss outer surface98may meet the mounting structure first side surface80at a (e.g., ˜90°) relatively sharp corner, or alternatively at a rounded and/or otherwise eased corner. Referring toFIG.4, the engine line aperture100extends radially through the engine case46and its elements56,62A and96from the peripheral boss outer surface98to the base inner side66. This engine line aperture100may be configured as a receptacle, a port or a pass through for the engine line54(seeFIG.2) as described below in further detail. The mounting apertures102projects radially into the peripheral boss96from the peripheral boss outer surface98. Each mounting aperture102may extend partially into the engine case46; e.g., each mounting aperture102may be a blind aperture. One or more or all of the mounting apertures102may alternatively extend radially through the engine case46; e.g., each mounting aperture102may be a through-hole. The mounting apertures102ofFIG.3are arranged on opposing lateral sides of the engine line aperture100; however, the present disclosure is not limited to such an exemplary arrangement. At least a portion of the support element62A and its peripheral boss96may be tapered. For example, referring toFIGS.3and4, a lateral end surface106of the support element62A and its peripheral boss96at the lateral distal end88A extends laterally and radially inward from the peripheral boss outer surface98towards (e.g., to) a radial outer surface108of the base56at the base outer side68. An end portion of the support element62A and its peripheral boss96ofFIG.4may thereby radially taper towards (e.g., to) the base56as the support element62A projects laterally away from the mounting boss60towards (e.g., to) the lateral distal end88A. The lateral end surface106ofFIG.4has a non-straight (e.g., curved, arcuate, splined, etc.) sectional geometry when viewed, for example, in a reference plane perpendicular to the axial centerline64. Of course, in other embodiments, the lateral end surface106may have a straight sectional geometry in the reference plane. Referring toFIG.3, the lateral end surface106may extend axially between the exterior side90A and the interior side92A of the support element62A and its peripheral boss96. The lateral end surface106ofFIG.3is contiguous with the mounting structure first side surface80. The lateral end surface106may meet the mounting structure first side surface80at a (e.g., ˜90°) relatively sharp corner, or alternatively at a rounded and/or otherwise eased corner. Referring toFIG.4, the lateral end surface106may also or alternatively be contiguous with the peripheral boss outer surface98. The lateral end surface106may meet the peripheral boss outer surface98at a relatively sharp corner, or alternatively at a rounded and/or otherwise eased corner. Referring toFIGS.3-5, one or more of the remaining boss support elements (e.g.,62B-D) may be configured as or otherwise include a reinforcement rib110B-D (generally referred to as “110”). By contrast to the support element62A, none of the support elements62B-D ofFIGS.3-5may be configured as or otherwise includes a mounting boss. One or more or all of the support elements62B-D ofFIGS.3-5, for example, may each be configured without a fastener aperture (e.g., threaded hole), a receptacle, a port and/or any other type of aperture configured for mounting, receiving and/or otherwise coupling with another component; e.g., an engine line or an engine line coupler. Each support element62B-D includes a respective support element outer surface112B-D (generally referred to as “112”) at its respective outer side87B-D. This support element outer surface112may extend laterally and radially inward from the mounting boss outer surface84towards (e.g., to) the base outer surface108. At least an end portion or an entirety of the respective support element62B-D ofFIGS.4and5may thereby radially taper towards (e.g., to) the base56as the respective support element62B-D projects laterally away from the mounting boss60towards (e.g., to) the lateral distal end88B-D. Each support element outer surface112B-D ofFIGS.4and5has a straight sectional geometry when viewed, for example, in a respective reference plane perpendicular to the axial centerline64. Of course, in other embodiments, one or more or all of the support element outer surfaces112may each have a non-straight (e.g., curved, arcuate, splined, etc.) sectional geometry when viewed in the respective reference plane. Referring toFIG.3, each support element outer surface112B-D may extend axially between the exterior side90B-D and the interior side92B-D of the respective support element62B-D. Each support element outer surface112ofFIG.3is contiguous with a respective one of the mounting structure side surfaces80,82. Each support element outer surface112may meet the respective mounting structure side surface80,82at a (e.g., ˜90°) relatively sharp corner, or alternatively at a rounded and/or otherwise eased corner. Referring toFIGS.4and5, each support element outer surface112may also or alternatively be contiguous with the mounting boss outer surface84. Each support element outer surface112may meet the mounting boss outer surface84at a relatively sharp corner, or alternatively at a rounded and/or otherwise eased corner. Each support element outer surface112may be angularly offset from the mounting boss outer surface84by an included angle104B-D; e.g., an obtuse angle. This included angle104B-D may be greater than one-hundred and ten degrees (110°) and less than one-hundred and sixty degrees (160°); e.g., between one hundred and forty degrees (140°) and one hundred and fifty-five degrees (155°), between one hundred and forty-five degrees (145°) and one hundred and fifty degrees (150°), etc. The present disclosure, however, is not limited to the foregoing exemplary positional relationship between the support element outer surface112and the mounting boss outer surface84. For example, the included angle104B-D may alternatively be less than one-hundred and ten degrees (110°). Referring toFIG.3, the support element62A and its peripheral boss96has an axial width114A that extends axially between the exterior side90A and the interior side92A. Each of the support elements62B-D and their reinforcement ribs110B-D has an axial width114B-D that extends axially between its exterior side90B-D and its interior side92B-D, which support element widths114B-D may be equal or uniquely sized. Each support element width114B-D is sized different (e.g., less) than the support element width114A. The support element width114A, for example, may be between one and one-half times (1.5×) and five times (5×) each support element width114B-D; e.g., between two times (2×) and three times (3×) each support element width114B-D. The present disclosure, however, is not limited to such an exemplary dimensional relationship. The support element width114A, for example, may be more than five times (5×) the support elements width114B-D. Each of the support element widths114A-D are smaller than an axial width116of the mounting boss60between its axial sides76and78. The support element62A and its peripheral boss96has a lateral length118A that extends laterally between the mounting boss60and the lateral distal end88A. Each of the support elements62B-D and their reinforcement ribs110B-D has a lateral length118B-D that extends laterally between the mounting boss60and the lateral distal end88B-D of the respective support elements62B-D, which support element lengths118B-D may be equal or uniquely sized. Each support element length118B-D is sized equal to or less than the support element length118A. The support element length118A, for example, may be between one times (1×), or one and one-tenth times (1.1×), and one-half times (1.5×) each support element length118B-D. The present disclosure, however, is not limited to such an exemplary dimensional relationship. The support element length118A, for example, may be more than one-half times (1.5×) or less than one times (1×) the support elements length118B-D. Each of the support element lengths118A-D may be equal to, smaller than or greater than a lateral length120of the mounting boss60between its lateral sides72and74depending on, for example, a size of the mounting boss60and/or a magnitude of a load to be transferred between the mounting boss60and the base56. Referring toFIG.2, the engine pylon14is mounted to the mounting boss60. The engine pylon14ofFIG.2, for example, radially engages (e.g., contacts) and is abutted next to (e.g., against) the mounting boss outer surface84. A mount122(e.g., flange) of the engine pylon14is mechanically fastened to the mounting boss60by one or more fasteners124(e.g., bolts), where each fastener124is mated with (e.g., threaded into) a respective one of the fastener apertures86. With this arrangement, the mounting structure58and its elements60and62are configured to structurally tie the engine pylon14to the remainder of the engine case46; e.g., the base56. The engine line54may be a fluid line for a sensor system, a lubrication system, a cooling system and/or a fuel system of the aircraft propulsion system10and its gas turbine engine12. The engine line54, for example, may be a fluid (e.g., gas and/or liquid) conduit such as a pipe or a hose. The engine line54may alternatively be an electrical line for a sensor system and/or an electrical system of the aircraft propulsion system10and its gas turbine engine12. The electrical line, for example, may be a single wire or a grouping (e.g., braid) of wires. However, for ease of description, the engine line54may be described below as the fluid conduit. The engine line54is mounted to the peripheral boss96. The engine line54ofFIG.2, for example, is coupled to an engine line coupler126; e.g., an end fitting. This engine line coupler126radially engages (e.g., contacts) and is abutted next to (e.g., against) the peripheral boss outer surface98. A mount128(e.g., flange) of the engine line coupler126is mechanically fastened to the peripheral boss96by one or more fasteners130(e.g., bolts), where each fastener130is mated with (e.g., threaded into) a respective one of the fastener apertures102. A bore in the engine line coupler126may fluidly couple an internal passage132of the engine line54with the engine line aperture100. Alternatively, the engine line54may project through the engine line coupler126to (or into) the engine line aperture100such that the internal passage132is directly fluidly coupled with the engine line aperture100. Still alternatively, the engine line54may project through the engine line coupler126and the engine line aperture100to an interior of the engine case46. While the engine line coupler126is shown inFIG.2as fixing the engine line54to the peripheral boss96, it is contemplated the engine line54may be fixed, attached or otherwise coupled without use of the engine line coupler126; e.g., the engine line54may be bonded to or otherwise attached to the peripheral boss96. The peripheral boss96ofFIG.6, for example, is configured with a single engine line aperture100; e.g., port, receptacle, etc. In some embodiments, referring toFIGS.3and4, the support element62A configured with the peripheral boss96may not be configured with a separate reinforcement rib. In other embodiments, referring toFIG.6, the support element62A may be configured with the peripheral boss96and a reinforcement rib134, for example, projecting (e.g., laterally) out from the peripheral boss96. The mounting structure58ofFIG.3is shown with the peripheral boss96at a particular corner of the mounting boss60. It is contemplated, however, that this peripheral boss96may alternatively be configured any other one of the support elements62B-D. Furthermore, while the mounting structure58ofFIG.3is shown with a single peripheral boss96, any one or more or all of the support elements62A-D may also or alternatively be configured with its own peripheral boss96A-D (generally referred to as “96”) as shown, for example, inFIG.7. The mounting boss60is described above as mounting the engine pylon14to the engine case46. However, it is contemplated the mounting boss60may alternatively be implemented to mount another (e.g., highly loaded) component to the engine case46. Furthermore, the peripheral boss96is described above as mounting a respective engine line54to the engine case46. However, it is contemplated the peripheral boss96may alternatively be implemented to mount another (e.g., lightly loaded, or unloaded) component to the engine case46. The engine case components56,58,60and62may be configured together as a unitary body. The base56and the mounting structure58, for example, may be cast, forged, milled, machined, additive manufactured and/or otherwise formed having a monolithic body. The term “monolithic” may describe a body configured from a continuous mass of material. Examples of a monolithic body include, but are not limited to, a cast body or a body milled, machined and/or forged from a billet of material. In contrast, a non-monolithic body may be formed from a plurality of discrete bodies that are fastened together to form a single part. While various embodiments of the present disclosure have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the disclosure. For example, the present disclosure as described herein includes several aspects and embodiments that include particular features. Although these features may be described individually, it is within the scope of the present disclosure that some or all of these features may be combined with any one of the aspects and remain within the scope of the disclosure. Accordingly, the present disclosure is not to be restricted except in light of the attached claims and their equivalents. | 30,652 |
11859507 | It is noted that the drawings of the disclosure are not to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the disclosure. In the drawings, like numbering represents like elements between the drawings. DETAILED DESCRIPTION OF THE INVENTION As an initial matter, in order to clearly describe the current disclosure it will become necessary to select certain terminology when referring to and describing relevant machine components within a turbine system. When doing this, if possible, common industry terminology will be used and employed in a manner consistent with its accepted meaning. Unless otherwise stated, such terminology should be given a broad interpretation consistent with the context of the present application and the scope of the appended claims. Those of ordinary skill in the art will appreciate that often a particular component may be referred to using several different or overlapping terms. What may be described herein as being a single part may include and be referenced in another context as consisting of multiple components. Alternatively, what may be described herein as including multiple components may be referred to elsewhere as a single part. In addition, several descriptive terms may be used regularly herein, and it should prove helpful to define these terms at the onset of this section. These terms and their definitions, unless stated otherwise, are as follows. As used herein, “downstream” and “upstream” are terms that indicate a direction relative to the flow of a fluid, such as the working fluid through the turbine system or, for example, the flow of air through the combustor or coolant through one of the turbine system's component systems. The term “downstream” corresponds to the direction of flow of the fluid, and the term “upstream” refers to the direction opposite to the flow. The terms “forward” and “aft,” without any further specificity, refer to directions, with “forward” referring to the front or compressor end of the engine, and “aft” referring to the rearward or turbine end of the engine. It is often required to describe parts that are at differing radial positions with regard to a center axis. The term “radial” refers to movement or position perpendicular to an axis. In cases such as this, if a first component resides closer to the axis than a second component, it will be stated herein that the first component is “radially inward” or “inboard” of the second component. If, on the other hand, the first component resides further from the axis than the second component, it may be stated herein that the first component is “radially outward” or “outboard” of the second component. The term “axial” refers to movement or position parallel to an axis, e.g., the turbine rotor axis. Finally, the term “circumferential” refers to movement or position around an axis. It will be appreciated that such terms may be applied in relation to the center axis of the turbine. In addition, several descriptive terms may be used regularly herein, as described below. The terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not. Where an element or layer is referred to as being “on,” “engaged to,” “disengaged from,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. As indicated above, the disclosure provides a method and system for aligning a component within a turbine casing, and a related turbine casing. In a top-on position, a location of the optical target and another, vertically spaced optical target on a horizontal joint (HJ) flange of the lower casing are measured at one or more primary axial locations. After removing at least the upper casing, the optical targets' locations are measured again, and the locations of a pair of reference points on an upper surface of the HJ flange, are measured. A prediction offset value is calculated for the component support position in the top-on position based on at least the measured locations. The prediction offset value may include a number of calculated adjustments. In one example, a tilt angle of the lower casing and a rotation angle of the lower casing can be calculated, and a vertical adjustment made based on both. In another example, a horizontal adjustment can be calculated based on the horizontal shift of the lower casing from the top-on to the top-off position. In another example, an HJ flange surface distortion can be identified by superimposing reference lines of the HJ flange surfaces and identifying any gaps at an inner or outer location of mating of the surfaces with the prediction offset value including a correction based on the surface distortion. Similar prediction offset values can be calculated for other secondary axial locations that include only one optical target. In any event, the component support position at a variety of axial locations may be adjusted by the prediction offset value to improve alignment at each axial location. The method and system reduce the lifting required and can address practically all of the alignment issues. A. TURBINE SYSTEM AND TURBINE CASING Referring to the drawings,FIG.1shows a perspective partial cut-away illustration of an illustrative turbine system in the form of a steam turbine (ST) system10. ST system10includes a rotor12that includes a turbine rotor14and a plurality of axially spaced rotor wheels18. Turbine rotor14has a rotor axis A. A plurality of rotating turbine blades20are mechanically coupled to each rotor wheel18. More specifically, turbine blades20are arranged in rows that extend circumferentially around each rotor wheel18. A plurality of stationary vanes22extends circumferentially around turbine rotor14, and the vanes are axially positioned between adjacent rows of turbine blades20. Stationary vanes22cooperate with turbine blades20to form a stage and to define a portion of a steam flow path through ST system10. In one embodiment of the present disclosure, as shown inFIG.1, ST system10comprises five stages. The five stages are referred to as L0, L1, L2, L3and L4. Stage L4is the first stage and is the smallest (in a radial direction) of the five stages. Stage L3is the second stage and is the next stage in an axial direction. Stage L2is the third stage and is shown in the middle of the five stages. Stage L1is the fourth and next-to-last stage. Stage L0is the last stage and is the largest (in a radial direction). It is to be understood that five stages are shown as one example only, and each turbine system may have more or less than five stages. Also, as will be described herein, the teachings of the invention do not require a multiple stage turbine. In operation, a working fluid, here steam,24enters an inlet26of ST system10and is channeled through stationary vanes22. Vanes22direct steam24downstream against turbine blades20. Steam24passes through the remaining stages imparting a force on turbine blades20causing turbine rotor14to rotate. At least one end of ST system10may extend axially away from rotor12and may be attached to a load or machinery (not shown) such as, but not limited to, a generator, and/or another turbine. While embodiments of the disclosure will be described relative to ST system10, it will be readily understood that the teachings of the disclosure are applicable to a variety of turbine systems and/or other industrial machines having heavy mating casings or parts that require component alignment. As shown in a side perspective view ofFIG.2, ST system10may include a turbine casing100including a lower casing102having a lower horizontal joint (HJ) flange104, and an upper casing106having an upper horizontal joint (HJ) flange108. (Note,FIG.2shows ST system10with any insulation and much of its piping removed.) Lower and upper casings102,106may each represent any degree of a 360° casing that collectively surround turbine rotor14. That is, upper casing(s)106and lower casing(s)102are collectively configured to surround turbine rotor14(FIG.1) and turbine blades20(FIG.1) coupled to the turbine rotor. The disclosure will be described relative to a single upper casing106and single lower casing102, it will be appreciated by those with skill in the art that the teachings are applicable to turbine systems having numerous upper and/or lower casings. In any event, upper casing106and lower casing102are configured to collectively surround turbine rotor14and turbine blades20coupled to turbine rotor14. Upper casing106and lower casing102can be attached, for example, by fasteners, at respective HJ flanges104,108. HJ flanges104,108extend radially outward from rounded portions of casings102,106to create connection flanges. While named “horizontal joint” flanges, as understood in the art, the HJ flanges104,108may diverge from horizontal. Each casing102,106has an inner radius (IR) (FIG.4) used for operations according to embodiments of the disclosure. Inner radius (IR) may vary depending on the prediction offset value being calculated. For example, inner radius (IR) may be from rotor axis A to an inner surface of each casing102,106, from rotor axis A to an outer surface of component120, or from rotor axis to some part of a relevant component support position124. Typically, upper casing106is removed during maintenance to expose turbine rotor14and internal components of ST system10. Upper casing106can be removed by removing any insulation and external piping (not shown), removing fasteners to lower casing102, and lifting it away with a crane, e.g., a heavy lift crane. Components within lower casing102can then be serviced. In many instances, the components may also be removed, serviced and replaced, requiring alignment thereof relative to casings102,106prior to re-use. Components that may require alignment upon replacement of upper casing106may include, for example, a diaphragm portion112(FIG.1), an inner casing portion114(FIG.1) and one or more stationary nozzle portions116(FIG.1). It is understood that the prior list of components is not comprehensive and a wide variety of components may require alignment. FIG.3shows a top down view in a top-off position of an illustrative component120in the form of a diaphragm122.FIG.3shows an occupied diaphragm support position1240having a diaphragm122therein; and a component (diaphragm) support position124E emptied of a respective diaphragm.FIG.4shows a partial cross-sectional view of an illustrative diaphragm122(shown transparent) in a component support position124in one side of lower casing102. As understood, any number of diaphragms122are axially spaced within casings102,106and extend within an inner radius of each casing102,106to interact with turbine blades20(FIG.1). Diaphragms122of lower casing102and upper casing106(not shown) mate at their respective circumferential ends132(FIG.4) to create a working fluid path with turbine blades20(FIG.1). As illustrated, each diaphragm122has an extension126at circumferential ends132(FIG.4) thereof that is supported by component support position124. In the example shown, component support position124may include a shim128fastened to a ledge130(FIG.4only). More particularly, component support position124may include ledge130(FIG.4only) on an inner radius of lower casing102, and shim128may be positioned thereon to support extension126of diaphragm122. Shim128and/or ledge130can be adjusted to align diaphragm122relative to turbine casing100, e.g., after service of ST system10(FIG.1). For example, shim128can be adjusted by increasing or decreasing its height relative to ledge130to adjust a vertical height of component120, i.e., to raise or lower diaphragm122. In addition or alternatively, shim128can be adjusted to change an angle (a) of an upper surface136thereof. In addition or alternatively, edge130can be adjusted similarly to shim128. While component120has been illustrated and described herein as a diaphragm122, it is understood that the teachings of the disclosure are applicable to a wide variety of alternative components120within turbine casing100. For example, as noted, component120may include at least one of a diaphragm portion112(FIG.1) (of diaphragm122), an inner casing portion114(FIG.1) and one or more stationary nozzle portions116(FIG.1). Further, while component support position124has been described as a ledge and shim arrangement, it is understood that a shim128may not be necessary, and ledge130could be adjusted alone. Further, it is emphasized that component support position124may take a variety of alternative forms other than a ledge and shim arrangement, and may include any form of support for a component120. Component support position124may also be located at a different location than indicated inFIGS.3-4, depending on the component. The component support position can also be directly on HJ flange104,108. The adjustment may be made by means of an adjusting screw or bolt. In accordance with embodiments of the disclosure, parts of turbine casing100can be provided with a number of selected reference points (RP) that can be used to calculate a prediction offset value that can be employed to adjust a component support position124to improve alignment of component120positioned at component support position124relative to rotor axis A upon replacing upper casing106to the top-on position. As shown inFIGS.2and4, turbine casing100may include a plurality of first optical targets140. Each first optical target140is positioned at one of a plurality of axial locations relative to a radially facing outer surface142of lower HJ flange104of lower casing102. In certain embodiments, first optical targets140are coupled to radially facing outer surface142of lower HJ flange104; however, other locations on an outer surface of lower casing102may be possible. Each first optical target140may include any now known or later developed optical target capable of detection using an appropriate measurement system. In one non-limited example, first optical target(s)140may include a spherically mounted retroreflector (SMR) adapter coupled to radially facing outer surface142of lower HJ flange104of lower casing102. First optical target(s)140may be coupled to radially facing outer surface142in any now known or later developed manner, e.g., welding, fasteners, etc. In one example, a measurement system144for measuring a location of optical target(s)140may include, for example, a laser measurement system such as a Vantage model laser tracker available from FARO Corp. of Lake Mary, FL, or a model AT401 laser tracker available from Leica Geosystems Inc. of Norcross, GA Measurement system144may be operatively coupled to an alignment system146, described herein. While a laser measurement system has been listed herein as an example, it is understood that wide variety of alternative measurement systems are available that are capable of the locating a reference point in three-dimensional space. Measurement system144may include but is not limited to: infrared, radar, etc. For purposes that will be described herein, turbine casing100may also include a second optical target148positioned at one or more of axial locations with first optical targets140. Axial locations that include both optical targets140,148are referred to hereafter as “primary axial locations,” while those with only first optical target140are referred to hereafter as “secondary axial locations.” As shown best inFIG.4, each second optical target148is vertically spaced from a respective first optical target140, e.g., on radial facing outer surface142of lower HJ flange104, by a distance D1. This vertical spacing D1may vary depending on, for example, the size of lower HJ flange104. The vertical spacing D1is predefined such that a spatial relationship between optical targets140,148at the selected primary axial locations is known. In one non-limited example, second optical targets148may also include an SMR adapter coupled to an outer surface of lower HJ flange104of lower casing102. Second optical target(s)148may be coupled to the outer surface in any now known or later developed manner, e.g., welding, fasteners, etc. In certain embodiments, second optical targets148are coupled to radially facing outer surface142of lower HJ flange104; however, other locations on an outer surface of lower casing102may be possible. In the example shown, three second optical targets148are shown, resulting in three primary axial locations, but any number may be employed. As illustrated, first optical targets140alone may also be positioned on lower HJ flange104at a number of secondary axial locations at which no second optical target148is present. If reference is made to simply “axial location” it refers to any axial location—primary and/or secondary axial locations, or other axial locations. The purposes of optical targets140,148and the primary and secondary axial locations will be described herein. FIG.4shows a number of reference points that can be used to identify issues that can impact any necessary adjustment to component support position124. The locations of the reference points relative to lower HJ flange104and/or upper HJ flange108may be predefined based on the geometry at the desired axial location of lower casing102, and can be measured by measurement system144according to embodiments of the disclosure. As will be described, the locations can be used by alignment system146to calculate a prediction offset value for one or more component support positions124in the top-on position. Adjusting component support position124in turbine casing100(FIG.2) by the prediction offset value improves an alignment of component120(FIG.3) positioned at component support position124relative to rotor axis A upon replacing upper casing106to the top-on position. In the disclosure, a ‘reference point’ indicates a fixed position on the upper or lower casing, e.g., of an optical target or other selected position, while a ‘location of a reference point X’ indicates a changeable, three dimensional position of a reference point X, e.g., as measured by measurement system144. The locations will be numbered, i.e., first, second, third, etc., for differentiation purposes. Note, each reference point may have a number of locations. In any event, locations may be indicated by any now known or later developed three dimensional coordinate system, e.g., using measurement system144as an origin. Measurement system144, as noted, may include any appropriate measurement system for measuring locations of reference points on casings102,106, e.g., using lasers. Alignment system146may receive the locations of the reference points at measurement module230(FIG.12) where calculation module232(FIG.12) calculates the prediction offset value. As shown inFIG.4, the following illustrative reference points may be defined at each selected primary axial location: a first reference point RP1at first optical target140coupled to an outer surface142(FIG.2) of lower HJ flange104; a second reference point RP2at second optical target148coupled to outer surface142(FIG.2) of lower HJ flange104and vertically spaced from first optical target140(FIG.2); a third reference point RP3on upper surface150; and a fourth reference point RP4on upper surface150. As will be described, upper casing106may include a number of reference points thereon including, for example, a fifth reference point RP5on a lower (as drawn) surface152of upper HJ flange108and a sixth reference point RP6on lower surface152of upper HJ flange108. In addition, secondary axial locations may also include reference points. As noted, secondary axial locations do not include second optical target148coupled to outer surface142(FIG.2) of lower HJ flange104. As shown inFIG.22, secondary axial locations may include seventh, eighth and ninth reference points RP7, RP8and RP9. As will be further described, seventh, eighth and ninth reference points RP7, RP8and RP9correspond in function to first, third and fourth reference points (RP1, RP3, RP4) at primary axial locations. In accordance with embodiments of the disclosure, at least one of the reference points has a known spatial relationship to component support position124such that a change in position of the reference point, i.e., as calculated in the form of the prediction offset value, can be used to adjust component support position124to provide the necessary change in position to component120(FIGS.3and15) to ensure alignment thereof in the top-on position. In the example shown, third reference point RP3has a known spatial relationship with component support position124, e.g., ledge130and/or shim128. The spatial relationship may be in any form. That is, a direct relationship in which third reference point RP3may have a defined vertical and/or radial offset from component support position124, and/or an indirect relationship in which third reference point RP3and component support position124each having a known relationship to another point, e.g., inner edge154of lower casing102. In any event, the spatial relationship can be used to calculate changes for component support position124. At secondary axial locations, seventh reference point RP7(FIG.22) may provide the same function as third reference point RP3for primary axial locations, i.e., it has a known spatial relationship with component support position124at the respective secondary axial location. As observed inFIG.4, spatial relationships between the reference points can be defined based on the known (expected) geometry of lower HJ flange104at each axial location. That is, the reference points can be used to define an expected spatial relationship for each axial location as lower HJ flange104and/or upper HJ flange108changes along axial cross-sections. For example, distance D1between first and second reference points RP1, RP2is defined. In addition, each axial location may have a different third reference point RP3and fourth reference point RP4and/or fifth reference point RP5and sixth reference point RP6that are selected, for example, to avoid structure at a given axial location, e.g., cooling channels as shown inFIG.14. Regardless, each set of third and fourth reference points RP3, RP4and each set of fifth reference points RP5, RP6may have defined spatial relationships with each other and other reference points, which can be verified through measurement in the top-off position. For example, a defined distance D2between third and fourth reference points RP3and RP4(and RP5and RP6) is defined and can be more precisely verified by measurement for each axial location. Further, fourth reference point RP4may be a defined distance D3from outer edge156of lower HJ flange104, and first reference point RP1(i.e., first optical target140) may be a defined distance D4from outer edge156of lower HJ flange104. As a result, a triangular spatial relationship160(see differently shaded triangle inFIG.4) between first reference point RP1, third reference point RP3and fourth reference point RP4, is known and can be verified through measurement. Fifth location L5of third reference point RP3on upper surface150of lower HJ flange104, sixth location L6of fourth reference point RP4on upper surface150of lower HJ flange104, and third location L3of first reference point RP1at first optical target140in the top-off position, may be measured at a selected axial location to identify (verify) triangular spatial relationship160. Consequently, as will be described, differences between an actual location of third reference point RP3as measured in the top-off position and a predicted top-on location thereof based on a translation of triangular spatial relationship160to the top-on position (i.e., based on a location of the first reference point RP1in the top-on position), can be used to calculate at least one form of the prediction offset value. Similar relationships exist for seventh, eighth, and ninth reference points RP7, RP8and RP9(FIG.22) at secondary axial locations. As noted,FIG.4also shows upper casing106with a number of reference points thereon (internal components not shown for upper casing106). For example, upper casing106may include fifth reference point RP5on lower (as drawn) surface152of upper HJ flange108and sixth reference point RP6on lower surface152of upper HJ flange108. In a top-on position, fifth reference point RP5is aligned with third reference point RP3, and sixth reference point RP6is aligned with fourth reference point RP4. Therefore, fifth and sixth reference points RP5and RP6may be distance D2apart. Fifth and sixth reference points RP5and RP6locations may also be known relative to edges of upper HJ flange108. Reference points can be defined relative to casings102,106by optical targets140,148, or by any other mechanism by which measurement system144can measure their location, e.g., marks or objects on a surface detectable by measurement system144, temporary measurement targets placed at the reference point (e.g., optical target, reflective tape, scribe marks, stamped marks, etc.), etc. B. POSSIBLE CASING ISSUES FIGS.5-11show schematic cross-sectional views of possible HJ flange104,108scenarios that may occur during a maintenance operation in which upper casing106is removed from lower casing102, i.e., to a top-off position. The scenarios illustrated can occur at any axial location, and at one or both sides of lower casing102. Each scenario may impact alignment of components120(FIG.3) within turbine casing100differently, and can be addressed according to the methodology described herein. For purposes of description,FIGS.5-11illustrate HJ flanges104,108from a perspective in which turbine rotor axis A is to the left of the side shown. As will be described, rotor axis A acts as a coordinate system origin for the methodology described. For brevity, rotor axis A is only shown inFIG.5; however, a reference line RL at which flanges104,108could potentially meet has been provided. Most of the parts that curve away for casings102,106have been omitted for clarity. It is appreciated that the diametrically opposing side of each casing102,106from that shown may have similar, symmetrical positioning. As understood the in the art, when HJ flanges104,108are separated, lower casing102and lower HJ flange104may spring upwardly or bow, and upper casing106and upper HJ flange108may drop or spring downwardly. As this occurs, lower HJ flange104rotates about rotor axis A, changing vertical positioning. Further, lower HJ flange104may tilt inwardly, tilt outwardly or simply move vertically. Similarly, upper HJ flange108may tilt inwardly, tilt outwardly or simply move vertically. In addition, an upper surface150of lower HJ flange104, and a lower surface152of upper HJ flange108may distort upon separation, i.e., the surfaces become non-planar. In this latter case, when casings102,106are mated together again, surfaces150,152may not meet in a surface-to-surface mating fashion, e.g., planar surface to planar surface, which may cause edges of casings102,106to not close, creating a leak. While casings102,106can be forcibly brought into planar engagement by way of fasteners that couple them together, the meeting of edges rather than surfaces, e.g., inner edges154or outer edges156, may impact the alignment of component120(FIG.3) inside the casings. WhileFIGS.5-11show schematic cross-sectional views of possible HJ flange104,108scenarios that may occur, they do not necessarily show the rotation of lower casing102about rotor axis A. Calculation of a prediction offset value (vertical adjustment) based on the rotation, among other things, will be illustrated elsewhere in the drawings. FIG.5shows an illustrative scenario1in which both HJ flanges104,108are parallel, i.e., surfaces150,152thereof are parallel to one another and reference line (RL). If brought together, inner edges154would meet nearly simultaneously with outer edges156, so the joint would not be open on either side. In this case, casings102,106have not tilt, they simply separated from one another vertically. FIG.6shows an illustrative scenario2in which HJ flanges104,108are not parallel and have tilt such that, if brought together, inner edges154would be initially separated, and outer edges156would touch first, leaving the joint open on the inside (left side, as shown). In the scenario illustrated, lower HJ flange104tilt counterclockwise, and upper HJ flange108tilt clockwise. FIG.7shows an illustrative scenario3in which both HJ flanges104,108are not parallel and have tilt such that, if brought together, outer edges156would be initially separated, and inner edges154would touch first, leaving the joint open on the outside (right side, as shown). In the scenario illustrated, lower HJ flange104tilt clockwise, and upper HJ flange108tilt counterclockwise. FIG.8shows an illustrative scenario4in which HJ flange104,108are not parallel and lower HJ flange104has tilt such that, if brought together, inner edges154would be initially separated, and outer edges156would touch first, leaving the joint open on the inside (left side, as shown). In the scenario illustrated, lower HJ flange104tilt counterclockwise, and upper HJ flange108did not tilt and remains parallel, e.g., to reference line RL. FIG.9shows an illustrative scenario5in which HJ flanges104,108are not parallel and lower HJ flange104has tilt such that, if brought together, inner edges154would be initially separated, and inner edges154would touch first, leaving the joint open on the outside (right side, as shown). In the setting illustrated, lower HJ flange104tilt clockwise, and upper HJ flange108did not tilt and remains parallel, e.g., to reference line RL. FIG.10shows an illustrative scenario6in which both HJ flanges104,108are parallel and both have tilt. Here, however, if brought together, inner edges154would meet nearly simultaneously with outer edges156, so the joint would not be open on either side. In the scenario illustrated, lower HJ flange104tilt clockwise, and upper HJ flange108tilt clockwise. FIG.11shows an illustrative scenario7in which both HJ flanges104,108are parallel and both have tilt. Here, similar toFIG.10, if brought together, inner edges154would meet nearly simultaneously with outer edges156, so the joint would not be open on either side. In the scenario illustrated, lower HJ flange104tilt counterclockwise, and upper HJ flange108tilt counterclockwise. Another issue that can occur in any of the previous scenarios is that surfaces150,152may not be planar after casing102,106separation. In this setting, inner edges154may not be in the same plane as outer edge156, or other point(s) therebetween may make the surfaces non-planar. C. ALIGNMENT SYSTEM Certain aspects of the disclosure may be embodied as an alignment system146, method or computer program product. Accordingly, the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, the present disclosure may take the form of a computer program product embodied in any tangible medium of expression having computer-usable program code embodied in the medium. Any combination of one or more computer usable or computer readable medium(s) may be utilized. The computer-usable or computer-readable medium may be, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a transmission media such as those supporting the Internet or an intranet, or a magnetic storage device. Note that the computer-usable or computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted, or otherwise processed in a suitable manner, if necessary, and then stored in a computer memory. In the context of this document, a computer-usable or computer-readable medium may be any medium that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer-usable medium may include a propagated data signal with the computer-usable program code embodied therewith, either in baseband or as part of a carrier wave. The computer usable program code may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc. Computer program code for carrying out operations of the present disclosure may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). The present disclosure is described below with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer program instructions may also be stored in a computer-readable medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instruction means which implement the function/act specified in the flowchart and/or block diagram block or blocks. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. FIG.12shows an illustrative environment200for alignment system146. To this extent, environment200includes a computer infrastructure202that can perform the various process steps described herein for alignment system146. In particular, computer infrastructure202is shown including a computing device204that comprises alignment system146, which enables computing device204to receive measurements and calculate prediction offset value for adjustments for casings102,106, i.e., by performing the process steps of the disclosure. Computing device204is shown including a memory212, a processor (PU)214, an input/output (I/O) interface216, and a bus218. Further, computing device204is shown in communication with an external I/O device/resource220and a storage system222. As is known in the art, in general, processor214executes computer program code, such as alignment system146, that is stored in memory212and/or storage system222. While executing computer program code, processor214can read and/or write data, such as alignment system146, to/from memory212, storage system222, and/or I/O interface216. Bus218provides a communications link between each of the components in computing device204. I/O device216can comprise any device that enables a user to interact with computing device204or any device that enables computing device204to communicate with one or more other computing devices. Input/output devices (including but not limited to keyboards, displays, pointing devices, etc.) can be coupled to the system either directly or through intervening I/O controllers. In any event, computing device204can comprise any general purpose computing article of manufacture capable of executing computer program code installed by a user (e.g., a personal computer, server, handheld device, etc.). However, it is understood that computing device204and alignment system146are only representative of various possible equivalent computing devices that may perform the various process steps of the disclosure. To this extent, in other embodiments, computing device204can comprise any specific purpose computing article of manufacture comprising hardware and/or computer program code for performing specific functions, any computing article of manufacture that comprises a combination of specific purpose and general purpose hardware/software, or the like. In each case, the program code and hardware can be created using standard programming and engineering techniques, respectively. Similarly, computer infrastructure202is only illustrative of various types of computer infrastructures for implementing the disclosure. For example, in one embodiment, computer infrastructure202comprises two or more computing devices (e.g., a server cluster) that communicate over any type of wired and/or wireless communications link, such as a network, a shared memory, or the like, to perform the various process steps of the disclosure. When the communications link comprises a network, the network can comprise any combination of one or more types of networks (e.g., the Internet, a wide area network, a local area network, a virtual private network, etc.). Network adapters may also be coupled to the system to enable the data processing system to become coupled to other data processing systems or remote printers or storage devices through intervening private or public networks. Modems, cable modem and Ethernet cards are just a few of the currently available types of network adapters. Regardless, communications between the computing devices may utilize any combination of various types of transmission techniques. As previously mentioned and discussed further below, alignment system146enables computer infrastructure202to calculate prediction offset value(s) that can be used to make adjustments to improve alignment of components120(FIG.4) within casings102,106(FIG.4). To this extent, alignment system146is shown including a measurement module230, and a calculation module232. Other system components234may also be provided. Operation of each of these systems is discussed further below. However, it is understood that some of the various systems shown inFIG.12can be implemented independently, combined, and/or stored in memory for one or more separate computing devices that are included in computer infrastructure202. Further, it is understood that some of the systems and/or functionality may not be implemented, or additional systems and/or functionality may be included as part of environment200. Alignment system146may be geographically located on-site, local to turbine system10, or it may be geographically remote from turbine system10, e.g., in a centralized turbine system control center. D. OPERATIONAL METHODOLOGY Referring to the flow diagram ofFIG.13, a method of aligning a component120(FIG.3) within turbine casing100(FIG.2) will now be described.FIG.14shows a perspective view of an illustrative lower casing102with a number of axial locations highlighted with cross-sectional planes,FIG.15shows an enlarged cross-sectional view of one side of HJ flanges104,108in a top-on position of the turbine casing,FIG.16shows an enlarged cross-sectional view of one side of HJ flanges104,108in an illustrative top-off position of the turbine casing, andFIG.17shows an enlarged, schematic cross-sectional view of an illustrative HJ flange104show potential adjustments. InFIGS.15-17, rotor axis A is to the left (off the page), as illustrated. As will be described, a number of processes occur with lower casing102and upper casing106attached in a top-on position, as shown inFIGS.2and15, and a number of processes occur with lower casing102and upper casing106in a de-coupled, top-off position, as shown in for example,FIGS.3-11,14and16. Processes P10-P22are carried out for at least one primary axial location along rotor axis A (FIG.1), i.e., where first and second optical targets140,148are both present (three shown in example inFIG.2). As observed inFIG.14, lower HJ flange104can change over an axial length thereof. For example, at different axial locations of lower HJ flange104(and upper HJ flange108), it can have different, for example: shape, radial position relative to turbine rotor axis A, radial thickness, and/or structure therein (e.g., cooling channels (see e.g.,FIG.14)) extending therethrough. Processing according to embodiments of the disclosure can be carried out at different axial locations to provide highly customized adjustments for component support positions124at each axial location. In addition, since different sides of lower and upper casings102,106can be differently situated even if evaluated at the same axial location, processes P10-P34can be carried out at one or both sides110L,110R (FIG.14) of turbine casing100(FIG.2) at each axial location. While one primary axial location can be used, it is typically advantageous to use a plurality of primary axial locations to obtain better improvement in overall alignment. Referring toFIGS.12and13, processes P10and P12are performed with lower and upper casings102,106in a top-on position, as shown inFIG.15. That is, upper casing106is coupled to lower casing102in a top-on position. In process P10, as shown inFIG.15, measurement system144measures a first location L1of first reference point RP1at first optical target140. As noted, first optical target140is coupled to outer surface142of lower HJ flange104. Measurement system144, as noted, may include any appropriate measurement system for measuring locations of reference points on casings102,106, e.g., using lasers. As noted, locations may be indicated by any now known or later developed three dimensional coordinate system. In process P12, as shown inFIG.15, measurement system144measures a second location L2of a second reference point RP2at a second optical target148coupled to outer surface142(FIG.2) of lower HJ flange104and vertically spaced from first optical target140(FIG.2). As noted, distance D1between first and second reference points RP1, RP2is defined, i.e., known. With processes P10and P12, alignment system146may receive locations L1, L2of reference points RP1, RP2at measurement module230for use by calculation module232to calculate the prediction offset value. Note, optional process P24occurring in a top-on position will be described further herein. In process P14, and as shown inFIG.16, upper casing106is removed from lower casing102. This operation can be completed using any now known or later developed casing removal process including, for example, removing any insulation, piping, casing fasteners, etc., and lifting upper casing106off of lower casing102. Upper casing106can be set aside for separate evaluation, as will be described herein. While not necessary, other parts that are internal to turbine casing100(FIG.2) may also be removed such as but not limited to: remaining portions of upper casing106, turbine rotor14(FIG.1), a lower portion of diaphragm122(lower diaphragm), and/or lower casing102portions. As shown inFIG.13, process P12and P14(and P24) may repeat for each primary (or secondary) axial location desired, e.g., three primary axial locations are shown inFIGS.2and14, and over 20 secondary axial locations are shown inFIG.2. Processes P16-P22, and optional steps P26-P30, are performed with lower and upper casings102,106in a top-off position, as shown inFIG.16. As shown inFIG.16, with upper casing106removed, lower casing102, and in particular, lower HJ flange104thereof, may shift position, e.g., spring upward, rotate about rotor axis A, tilt inwardly or outwardly, etc.FIG.16shows only one possible scenario which matchesFIG.6but includes rotation; however, lower casing102may take any position described inFIGS.5-11. It is understood that the processing may be applied to any scenario. In process P16, with at least upper casing106removed from lower casing102in a top-off position, measurement system144measures a third location L3of first reference point RP1at first optical target140. Further, in process P18, with at least upper casing106removed from lower casing102in a top-off position, measurement system144measures a fourth location L4of second reference point RP2at second optical target148. The shift in position of lower casing102can be observed by comparing third and fourth locations L3, L4to first and second locations L1, L2(FIG.15, and shown in phantom inFIG.16). In theFIG.16example, lower HJ flange104has moved vertically upward and tilt inwardly (counterclockwise) from the position shown inFIG.15. Lower HJ flange104may have also rotated, e.g., counterclockwise, about rotor axis A. In process P20, with at least upper casing106removed from lower casing102in a top-off position, measurement system144measures a fifth location of third reference point RP3on upper surface150of lower HJ flange104. As noted, third reference point RP3has a known spatial relation to component support position124of component120in lower casing102. In process P22, with at least upper casing106removed from lower casing102in a top-off position, measurement system144measures a sixth location of fourth reference point RP4on upper surface150of lower HJ flange104of lower casing102. As noted, fourth reference point RP4is spaced from third reference point RP3on upper surface150of lower HJ flange104by a distance D1. After processes P16-P22, alignment system146may receive locations L3, L4, L5and L6of reference points RP1, RP2, RP3, RP4, respectively, at measurement module230(FIG.12) for use by calculation module232(FIG.12) to calculate the prediction offset value. As shown inFIG.16, triangular spatial relationship160of reference points RP1, RP3and RP4can be measured, i.e., verifying actual spacing and angular relationships thereof, at each axial location. With reference toFIGS.13and22, processes P24-P30are optional measurement steps for secondary axial locations. In process P24, in a top-on position shown partially inFIG.22, measurement system144measures a seventh location L7of a seventh optical target RP7at a first optical target140at secondary axial location (just RP7at seventh location L7of lower casing102shown in top-on position inFIG.22). Seventh reference point RP7is substantially identical in function to first reference point RP1, except it is for a secondary axial location. That is, first optical target140is located at a different axial location than first optical target140inFIG.16. In process P26, in a top-off position, shown inFIG.22, measurement system144measures an eighth location L8of seventh reference point RP7at first optical target140at the secondary axial location. In process P28, in a top-off position, measurement system144measures a ninth location L9of an eighth reference point RP8on upper surface150of lower HJ flange104. Eighth reference point RP8is substantially identical in function to third reference point RP3, except it is for a secondary axial location. Hence, eighth reference point RP8has a known spatial relation to the component support position124of component120(FIG.4) in lower casing102at the respective secondary axial location. In process P28, in a top-off position, measurement system144measures, a tenth location L10of a ninth reference point RP9on upper surface150of lower HJ flange104. Ninth reference point RP9is substantially identical in function to fourth reference point RP4, except it is for a secondary axial location. Hence, ninth reference point RP9is spaced from eighth reference point RP8on upper surface150of lower HJ flange104. Top-off position measurement processes (P16-P30) may repeat for any desired number of primary and/or secondary axial locations. Measurement module230(FIG.12) may receive all of the measured locations L1-L10. In process P32, calculation module232(FIG.12) may calculate the prediction offset value for component support position124in the top-on position based on first, second, third, fourth, fifth and sixth locations L1-L6and inner radius (IR) of lower casing102for at least one of the primary axial locations. In addition, calculation module232(FIG.12) may also calculate the prediction offset value for component support position124in the top-on position based on seventh, eighth, ninth and tenth locations L7-L10and inner radius (IR) of lower casing102for at least one of the secondary axial location(s). It is also noted that calculation of the prediction offset value for component support position124in the top-on position for a first side of the turbine casing100includes accounting for the prediction offset value for the component support position124in the top-on position for a second, opposite side of the turbine casing. That is, the calculation balances the prediction offset value for each side to ensure changes to one side do not negatively impact or disturb changes to the other side, e.g., rotational adjustments that counteract one another. Process P32can take a variety of forms that can be performed individually, or together, in any combination. Consequently, the prediction offset value can take a variety of forms. In process P34, the method may include a user adjusting component support position124in turbine casing100(FIG.2) by the prediction offset value. The adjusting changes component support position124position to improve an alignment of component120(FIG.15) with rotor axis A upon replacing upper casing106of turbine casing100(FIG.2) to the top-on position. The adjusting may include, for example, as shown inFIG.17, a change in a height (H) of component support position124, e.g., by changing shim128and/or ledge130. In any event, an alignment of component120(FIG.4) positioned at component support position124is improved relative to rotor axis A upon replacing upper casing106to the top-on position (FIG.15). Process P34can take a variety of forms that can be performed individually, or together, in any combination, e.g., depending on the prediction offset value form. The following sections will further describe the types of prediction offset value(s) that can be calculated by calculation module232(FIG.12) in process P32, and the related adjustment(s) that can be performed based on the prediction offset value(s) in process P34. a. Prediction Offset Value with Vertical Adjustment In certain embodiments, prediction offset value may include a vertical adjustment. In a simplified form, as shown inFIG.16, vertical adjustments can be determined directly from a vertical change in first location L1and third location L3of first reference point RP1, i.e., between the top-on position and the top-off position. As described previously, and as shown in detail inFIG.17, third reference point RP3and fourth reference point RP4on upper surface150of lower HJ flange104, and first reference point RP1at first optical target140, define triangular spatial relationship160(shaded triangle). More specifically, triangular spatial relationship160represents the location of reference points RP1, RP3and RP4on lower HJ flange104as they are expected to exist. Triangular spatial relationship160thus provides a baseline through which changes in lower HJ flange104can be detected. Triangular spatial relationship160can be identified, for example, based on initial designs and/or manufacturing records of lower HJ flange104, or based on previous manufacturing records of changes to lower HJ flange104. However, triangular spatial relationship160may also be identified (or verified) by calculation module232(FIG.12) based on the measured locations of reference points RP1, RP3, RP4on lower HJ flange104in the top-off position in process P16, P20and P22. As shown inFIG.16, calculation module232also determines a rotation angle (a) of lower HJ flange104about rotor axis A by calculating an angle between a first vector V1extending from rotor axis A to first location L1of first optical target140in top-on position and a second vector V2from rotor axis A through third location L3of first optical target140in the top-off position. As shown inFIG.18, calculation module232can translate triangular spatial relationship160to the top-on position based on first reference point RP1at first location L1in the top-on position and rotation angle (α) of lower HJ flange104about rotor axis A. That is, it rotates the triangular spatial relationship by rotation angle (α). The translating creates a predicted top-on location LP for third reference point RP3in the top-on position. In other words, calculation module232virtually places triangular spatial relationship160in the top-on position, using first reference point RP1as the starting point. As shown inFIG.18, triangular spatial relationship160may be moved vertically and/or rotated to match the rotation angle (α) of lower HJ flange104in the top-on position. In this setting, predicted top-on location LP of third reference point RP3indicates where vertically third reference point RP3should be if there is no distortion in lower HJ flange104. Calculation module232calculates any vertical difference (Δz1) between (actual) fifth location L5of third reference point RP3as measured and predicted top-on location LP for third reference point RP3from expected triangular spatial relationship160. Any vertical difference (Δz1) indicates a vertical change (FIGS.17and18) in the location of third reference point RP3caused, for example, by distortion in lower HJ flange104from use. Calculation module232(FIG.12) calculates a vertical adjustment based on any vertical difference (Δz1) of lower HJ flange104. Process P34may include adjusting component support position124to one of raise or lower (H) the component support position124based on the vertical adjustment and the known spatial relation of third reference point RP3to component support position124of component120in lower casing102. For example, if predicted top-on position LP is 1 millimeter higher than the actual, fifth location L5of third reference point RP3, then component support position124, e.g., ledge130and/or shim128, can be lowered in the tops off condition to accommodate the distortion in lower HJ flange104so that it is in the correct location when the tops is on and bolted. In other embodiments, as also shown inFIG.16, vertical adjustments can also be determined from based on a tilt angle (β) of lower HJ flange104, i.e., between the top-on position and the top-off position. That is, tilt angle (β) of lower HJ flange104also indicates a vertical change of third reference point RP3between the top-on position and the top-off position. Here, calculation module232(FIG.12) calculates the prediction offset value by, as shown inFIG.16, determining a tilt angle (β) of lower HJ flange104by calculating an angle between a first reference line (FRL) extending through first and second locations L1, L2(shown in phantom inFIG.16, and solid line inFIG.15) of first and second optical targets140,148in top-on position (FIG.15), and a second reference line (SRL) extending through third and fourth locations L3, L4of first and second optical targets140,148in the top-off position (FIG.16). Tilt angle (β) captures any inward or outward tilting of lower HJ flange104that changes its radial distance from rotor axis A, and a vertical position of component support position124. In the scenarios ofFIG.16andFIGS.6,8and11, lower HJ flange104tilts counterclockwise to the top-off position. InFIGS.7,9and10scenarios, lower HJ flange104tilts clockwise to the top-off position. Here, as shown inFIG.18, calculation module232also calculates any additional vertical difference (Δz2) between (actual) fifth location L5of third reference point RP3as measured and predicted top-on location LP for third reference point RP3from tilt angle (β) of lower HJ flange104. Note, vertical difference (Δz2) is shown in an exaggerated size for purposes of clarity of illustration, e.g., Δz1may not be smaller than Δz2. Tilt angle (β) of lower HJ flange104may be translated to, for example, reference point RP4and a vertical difference at third reference point RP3evaluated to identify a change in position of third reference point RP3caused by tilting of lower HJ flange104. Any vertical difference (Δz2) indicates an additional vertical change (FIG.18) in the location of third reference point RP3caused, for example, by distortion in lower HJ flange104from use. Calculation module232(FIG.12) calculates a vertical adjustment based on any vertical difference (Δz1) and tilt angle (β), i.e., any vertical difference (Δz2), of lower HJ flange104. Process P34, as noted previously, may include adjusting component support position124to one of raise or lower (H) component support position124based on the vertical adjustment and the known spatial relation of third reference point RP3to component support position124of component120in lower casing102. For example, if predicted top-on position LP is a determined to be an additional 0.2 millimeters off due to tilting (i.e., collectively 1.2 millimeter higher than the actual, fifth location L5of third reference point RP3), then component support position124, e.g., ledge130and/or shim128, can be lowered in the tops off condition to accommodate the distortion in lower HJ flange104so that it is in the correct location when the tops is on and bolted. b. Prediction Offset Value with Horizontal Adjustment Referring toFIG.19, calculation module232calculate a first horizontal difference (Δy1) between first location L1of first optical target140in the top-on position (dashed lines) and third location L3of first optical target140in top-off position (solid lines) at a first side of lower casing102, and a second horizontal difference (Δy2) between first location L1of first optical target140in top-on position (dashed lines) and third location L3of first optical target140in top-off position (sold lines) at a second side of lower casing102. Calculation module232sums first horizontal difference (Δy1) and second horizontal difference (Δy2) to attain a horizontal adjustment. For example, if first horizontal difference (Δy1) is 8 units, and second horizontal difference (Δy2) is −5 units, the sum and horizontal adjustment would be 3 units. In process P34, the adjusting would include adjusting component support position124based on the horizontal adjustment and the known spatial relation of third reference point RP3(FIGS.16-18) to component support position124(FIGS.16-18) of component120in lower casing102. c. Prediction Offset Value with HJ Flange Surface Distortion Adjustment Referring toFIGS.13,20and21, in certain embodiments, the prediction offset value may include a HJ flange104,108surface distortion adjustment to component support position124.FIG.20shows a schematic cross-sectional view of lower HJ flange104and upper HJ flange108in a top-off position with axis on the right. It is noted that while upper casing106is shown elevated above lower casing102, it may actually be laying in any orientation off of lower casing, e.g., in a support remote from lower casing102, flipped over on a floor, etc. As illustrated, with upper casing106in position to be mounted to lower casing102(virtually, with perhaps HJ flange surfaces beginning to touch), a gap G may exist, in the example shown, between third reference point RP3and fifth reference point RP5. Gap G represents an opening that would remain when lower casing102and upper casing106are moved to the top-on position caused by HJ flange surface distortion and in existence prior to closing the gap as upper casing106is fastened to lower casing102. As illustrated in the example ofFIG.21, if lower casing102and upper casing106are moved to the top-on position, inner edges154would meet before outer edges156of HJ flanges104,108, creating a gap G at an outer location near third reference point RP3and fifth reference point RP5. Note, gap G is shown in an exaggerated size in the drawings for purposes of clarity of illustration. Gap G disappears as casings102,106are fastened together. It can be observed inFIG.20that gap G is at least partially correlated to tilt angle (β), such that a prediction offset value to address gap G can be based, in part, on tilt angle (β). In one non-limiting example, a prediction offset value to address gap G can be based on half of tilt angle (β), assuming half of tilt angle (β) is absorbed by each HJ flange104,108during reconnection of casings102,106. In process P32, calculation module232can calculate the prediction offset value for component support position124in the top-on position based on at least the first, second, third, fourth, fifth and sixth locations L1-L6of lower casing102and any gap G. In one example, calculation module232can calculate the prediction offset value to include a HJ flange surface distortion adjustment at third reference point RP3to accommodate half of tilt angle (β) to address gap G. It is appreciated that gap G could also be between fourth and sixth reference points RP4, RP6if HJ flanges104,108tilt in an opposite direction. It is also appreciated that no gap G may exist where HJ flanges104,108remain parallel to one another. In process P34, component support position124(see e.g.,FIG.18) may be adjusted in turbine casing100(FIG.2) by the prediction offset value including the HJ flange surface distortion adjustment. In an optional embodiment, in order to confirm the presence and/or extent of gap G, in certain embodiments, as shown inFIG.20, calculation module232can also calculate any gap G at an inner location near third reference point RP3and fifth reference point RP5, or an outer location near fourth reference point RP4and sixth reference point RP6based on an angular relationship between a first reference line RL1and a second reference line RL2and the inner radius IR of lower casing102. Again, gap G represents an opening that would remain when lower casing102and upper casing106are moved to the top-on position caused by HJ flange surface distortion and in existence prior to closing the gap as upper casing106is fastened to lower casing102. As illustrated in the example ofFIG.21, if lower casing102and upper casing106are moved to the top-on position, inner edges154would meet before outer edges156of HJ flanges, creating a gap at an outer location near third reference point RP3and fifth reference point RP5. As shown inFIG.20, in process P32, calculation module232identifies a first reference line RL1through third reference point RP3and fourth reference point RP4on lower HJ flange104in a top-off position. Further, in process P32, calculation module232identifies a second reference line RL2through a fifth reference point and a sixth reference point of a lower (as shown) surface152of upper HJ flange108. As illustrated, rotor axis A is known for lower casing102, and a rotor axis A′ is (virtually) known for upper casing106, e.g., the latter based on its shape, inner radius and perhaps other dimensions. As shown inFIG.21, calculation module232establishes an angular relationship between first reference line RL1and second reference line RL2by superimposing rotor axis A′ of upper HJ flange108in the top-off position with rotor axis A of lower HJ flange104in the top-off position. Calculation module232can then calculate (confirm) any gap G at an inner location near third reference point RP3and fifth reference point RP5, or an outer location near fourth reference point RP4and sixth reference point RP6based on the angular relationship between first reference line RL1and second reference line RL2and the inner radius IR of lower casing102. Again, gap G represents an opening that would remain when lower casing102and upper casing106are moved to the top-on position caused by HJ flange surface distortion and in existence prior to closing the gap as upper casing106is fastened to lower casing102. As illustrated in the example ofFIG.21, if lower casing102and upper casing106are moved to the top-on position, inner edges154would meet before outer edges156of HJ flanges, creating a gap at an outer location near third reference point RP3and fifth reference point RP5. Gap G can be calculated (confirmed) by, for example, differencing a length of lines IL and line EL, which are both parallel to vertical axis z. IL extends between inner edges154, and EL extends between outer edges156. The location of inner and outer edges154,156can be (virtually) calculated based on the other reference points locations and inner radius IR. It is recognized, based on the scenarios inFIGS.5-11, a gap may also exist at the inner location. Calculation module232calculates the prediction offset value for component support position124in the top-on position based on at least the first, second, third, fourth, fifth and sixth locations L1-L6of lower casing102and any gap. In process P34, component support position124(see e.g.,FIG.18) may be adjusted in turbine casing100(FIG.2) by the prediction offset value including the HJ flange surface distortion adjustment. d. Prediction Offset Value for Secondary Axial Locations As noted previously, any number of secondary axial locations (FIG.2) may be provided along rotor axis A that are different than each primary axial location. As shown inFIGS.2,14and22, each secondary axial location includes first optical target140but no second optical target148, i.e., they have only first optical target140. Embodiments of the disclosure for at least one secondary axial location may occur at one or both sides of turbine casing100. In process P24-P28, measurement system144measures seventh, eighth, ninth and tenth locations L7-L10, as shown inFIGS.13and22, at a secondary axial location. Measurement module230(FIG.12) may receive locations L7-L10, and in process P32, calculation module232(FIG.12) may calculate the prediction offset value for component support position124in the top-on position based on seventh, eighth, ninth and tenth locations L7-L10and inner radius IR of lower casing102for at least one of secondary axial location. Any of the aforementioned prediction offset values for primary axial locations can be calculated for each secondary axial location. Where tilt angle (β) is required for the calculation, the value is unknown for each secondary axial location because no second reference point RP2and second optical target148is provided at those axial locations. In this case, the calculation may use the tilt angle (β) value of the nearest primary axial location. In process P34, component support position124in turbine casing100(FIG.2) at secondary axial location(s) may be adjusted by the prediction offset value therefor in a similar fashion as that described relative to the primary axial locations. The alignment of component120(FIG.15) positioned at component support position124for secondary axial location(s) is improved relative to rotor axis A upon replacing upper casing106to the top-on position. Processing may be completed by replacing any parts removed from lower casing102and/or upper casing106, and replacing upper casing106on lower casing102, and fastening it back in place per any now known or later developed technique. E. CONCLUSION Embodiments of the disclosure provide a method, system and turbine casing for aligning components that does not require numerous removing steps of the upper casing, thus making the process simpler, safer and less time consuming. The method also provides accurate results without direct measurement of component support positions. The method is also highly flexible and can handle unsymmetrical turbine casings. Technical effect is an alignment system capable of providing adjustments for one or more casings of a turbine casing to align components to be supported therein. The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions. As discussed herein, various systems and components are described as “receiving” data (e.g., locations, etc.). It is understood that the corresponding data can be obtained using any solution. For example, the corresponding system/component can include measurement system144or another system capable of generating and/or being used to generate the data, retrieve the data from one or more data stores (e.g., a database), receive the data from another system/component, and/or the like. When the data is not generated by the particular system/component, it is understood that another system/component can be implemented apart from the system/component shown, which generates the data and provides it to the system/component and/or stores the data for access by the system/component. The foregoing drawings show some of the processing associated according to several embodiments of this disclosure. In this regard, each drawing or block within a flow diagram of the drawings represents a process associated with embodiments of the method described. It should also be noted that in some alternative implementations, the acts noted in the drawings or blocks may occur out of the order noted in the figure or, for example, may in fact be executed substantially concurrently or in the reverse order, depending upon the act involved. Also, one of ordinary skill in the art will recognize that additional blocks that describe the processing may be added. Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. “Approximately” as applied to a particular value of a range applies to both values, and unless otherwise dependent on the precision of the instrument measuring the value, may indicate +/−10% of the stated value(s). The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The embodiment was chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated. | 75,612 |
11859508 | It should be noted that the figures disclose the invention in detail for implementing the invention, said figures can of course be used to better define the invention if necessary. DETAILED DESCRIPTION In a known manner, with reference toFIG.3, an aircraft turboshaft engine100extends along a longitudinal axis X and enables an aircraft to be propelled from the acceleration of an incoming air flow in the turboshaft engine100and circulating from upstream to downstream. Hereinafter, the terms “upstream” and “downstream” are defined with respect to the longitudinal axis X oriented from upstream to downstream. Similarly, the terms “internal” and “external” are defined along the radial direction with respect to the longitudinal axis X. In a known manner, with reference toFIG.3, an aircraft dual-flow turboshaft engine100comprises a radially internal primary vein4in which a first part of the incoming air flow, called primary air flow, circulates and a radially external secondary vein102in which a second part of the incoming air flow, called secondary air flow, circulates. In a known manner, with reference toFIG.3, an aircraft dual-flow turboshaft engine100comprises, from upstream to downstream, an air intake comprising a fan103for directing the incoming air flow towards the primary vein4and the secondary vein102, a compressor1for compressing the primary air flow, a combustion chamber105and a turbine106. In a known manner, with reference toFIG.4representing a close-up view A2ofFIG.3, the compressor1comprises a low pressure compressor110located upstream, a high pressure compressor3located downstream and an intermediate casing2axially connecting the low pressure compressor110and the high pressure compressor3. In a known manner, with reference toFIG.4, the intermediate casing2comprises an internal shell21internally delimiting the primary vein4, an external shell22externally delimiting the primary vein4and support arms23extending between the internal shell21and the external shell22. In a known manner, with reference toFIG.4, the high pressure compressor3comprises alternating stators31, also called straighteners, and rotors32axially mounted along the axis X to respectively guide and accelerate the primary air flow. As previously set forth, the stator located furthest upstream of the high pressure compressor3is hereinafter referred to as the inlet guide wheel33and is known to the person skilled in the art by its abbreviation “IGW”. The high pressure compressor3further comprises an external casing35externally delimiting the primary vein4. In a known manner, with reference toFIG.4, the inlet guide wheel33comprises a fixed retaining annulus34of axis X internally delimiting the primary vein4and a plurality of vanes38mounted between the retaining annulus34and the external casing35of the high pressure compressor3. In this example, the retaining annulus34and the external casing35respectively comprise a plurality of internal recesses36and a plurality of external recesses37, respectively formed at their external periphery, for mounting the vanes38. In this example, the inlet guide wheel33comprises a vane shimming system39for adapting the orientation of the vanes38depending on the flight conditions. According to the invention, with reference toFIG.4, the compressor1comprises a blocking device5between the retaining annulus34and the intermediate casing2. With reference toFIGS.5and6, this blocking device5comprises at least one first member6integral with the intermediate casing2and at least a second member7integral with the retaining annulus34. According to the invention, the second member7is configured to cooperate with the first member6in order to block a tangential movement of the retaining annulus34with respect to the intermediate casing2along the axis X while allowing axial movement and radial movement of said retaining annulus34with respect to said intermediate casing2along the axis X. This tangential blocking advantageously makes it possible, upon ingestion of foreign bodies, such as a bird, to avoid generating a mechanical moment about the axis X on the retaining annulus34of the inlet guide wheel33that could damage the vanes38. The radial and axial degrees of freedom, on the other hand, avoid creating a hyperstatic connection between the intermediate casing2and the inlet guide wheel33, and thus preserve the performance of the turboshaft engine100. According to one aspect of the invention, as illustrated inFIGS.5and6, the blocking device5comprises a plurality of first members6and second members7. Preferably, the blocking device5comprises at least three first members6to ensure an effective, distributed and redundant tangential blocking. Preferably also, the blocking device5comprises at most six first members6to limit the overall size, as illustrated in the example ofFIG.5. Similarly, the blocking device5comprises at least three second members7and at most six second members7. Preferably also, the blocking device5comprises as many second members7as first members6, as in the example ofFIGS.5and6, so that each first member6cooperates with a second member7, two by two. It goes without saying, however, that the number of first members6and the number of second members7could be different. The structural characteristics of a first member6and a second member7are successively described thereafter before describing their cooperation. In this embodiment, all first members6are identical. Therefore, for the sake of clarity and conciseness, only a first member6will be described from now on. According to one aspect of the invention, as represented inFIG.7Arepresenting a close-up view A4ofFIG.5, each first member6is integral with the internal shell21of the intermediate casing2. In particular, each first member6is attached to a downstream part of the internal shell21. With reference toFIG.7B, the downstream part of the internal shell21comprises a first radial wall24, an internal second radial wall26located downstream of the first radial wall24and radially internal to said first radial wall24, and a third axial wall25connecting the first radial wall24and the second radial wall26so as to form a concavity. In this example, the first member6is mounted in the concavity and is integral with the first radial wall24on the one hand and the third axial wall25on the other hand. As illustrated inFIG.7B, the first member6extends axially protruding downstream with respect to the second radial wall26. The blocking device5is thus located axially between the retaining annulus34and the internal shell21and has a small overall size. According to another aspect of the invention, as illustrated inFIGS.5and7A, the first member6is located at the same angular position as a support arm23, to limit the overall size. The walls24,25,26are not annular but form radial segments which are angularly positioned at the positions of the support arms23. In the example ofFIG.5, the first six members6are thus located at the same angular position as a support arm23. Advantageously, advantage is taken of the reinforcement of the internal shell21at the support arms23to form the first members6. The first members6thus have a robust structure as will be set forth later. They can thus absorb any shock or tangential movement of the retaining annulus34. It goes without saying, however, that only a part of the first members6can be located at the same angular position as a support arm23, or even that the first members625could be located at a different angular position depending on the locations available on the internal shell21. According to one aspect of the invention, as illustrated inFIGS.7A and7B, the first member6comprises a downstream face63-2, located downstream of the first radial downstream wall24of the internal shell21. Preferably, the downstream face63-2is parallel to said first radial wall24. The first member6further comprises side faces63-1,63-3connecting the downstream face63-2and the first radial wall24so that the radial section of the first member6is substantially rectangular. The downstream face63-2and the side faces63-1,63-3together delimit a median volume, extending axially protruding downstream from the first radial wall24and radially protruding outwards from the third axial wall25. This median volume advantageously allows the creation of a tangential blocking by cooperation with the second member7, while allowing a radial and axial movement. In particular, the side faces63-1,63-3form tangential stop faces as will be set forth later. According to another aspect of the invention, as illustrated inFIGS.7A and7B, the first member6comprises a foot volume that is radially internal to the median volume and a head volume that is radially external to the median volume. In particular, the foot volume is located between the median volume and the third axial wall25of the internal shell21. Preferably, as illustrated inFIGS.7A and7B, the median volume is in the form of a rectangular parallelepiped in the orthogonal plane X1, Y1, Z1, where X1 refers to the axial direction parallel to the axis X, Y1 to the tangential direction with respect to the axis X and Z1 to the radial direction with respect to the axis X. Preferably, the radial height H63of the median volume is large enough for optimal cooperation between the first member6and the second member7and small enough to limit the overall size. Similarly, the tangential length L63and/or the axial thickness E63are large enough for optimal cooperation between the first member6and the second member7and small enough to limit the overall size. As illustrated inFIGS.7A and7B, the first member6comprises a foot downstream face64-2connecting the downstream face63-2and the second radial wall26as well as two foot side faces64-1,64-3connecting the side faces63-1,63-3and the third axial wall25. The foot downstream face64-2and the foot side faces64-1,64-3together define the foot volume, in cooperation with the first radial wall24and the third axial wall25. Preferably, the tangential foot length L64separating the two foot side faces64-1,64-3at the axial downstream wall25is greater than the tangential length L63, so that the foot volume has a large contact section with the third axial wall25, thereby improving the mechanical shear strength. In other words, the foot side faces64-1,64-3are oblique to the radial direction Z1 forming bevels in the foot volume. These bevels have the advantage of avoiding forming a right angle between the side faces63-1,63-3and the foot side faces64-1,64-3, thus avoiding the appearance of local cracks and microcracks. Preferably also, the foot axial thickness E64separating the foot downstream face64-2from the first radial downstream wall24at the radial downstream wall25is less than the axial thickness E63, so that the median volume extends axially protruding downstream. In other words, the foot downstream face64-2is oblique with respect to the radial direction Z1, so as to avoid forming a right angle between the downstream face63-2and the foot downstream face64-2, thus avoiding the appearance of local cracks and microcracks. As illustrated inFIGS.7A and7B, the first member6further comprises an external face61, a head downstream face62-2connecting the downstream face63-2and the external face61, and two head side faces62-1,62-3connecting the side faces63-1,63-3and the external face61. The external face61, the head downstream face63-2and the head side faces63-1,63-3together delimit the head volume, in cooperation with the first radial wall24. Preferably, the section of the head volume of the first member6is smaller than that of the median volume so as to facilitate cooperation with the second member7, in particular, during relative movements along the radial direction. In this example, the tangential head length L61of the external face61is smaller than the tangential length L63. In other words, the head side faces62-1,62-3are oblique with respect to the radial direction Z1 forming bevels in the head volume. These bevels have the advantage of facilitating cooperation between the first member6and the second member7as well as avoiding forming a right angle between the side faces63-1,63-3and the head side faces62-1,62-3, thus avoiding the appearance of cracks and local microcracks. Preferably also, the head axial thickness E61of the external face61is less than the axial thickness E63, so that the median volume extends axially protruding downstream. In other words, the head downstream face62-2is oblique with respect to the radial direction Z1. According to a preferred aspect of the invention, each first member6forms a one-piece assembly with the internal shell21of the intermediate casing2. In other words, each first member6is made of the material of the internal shell21of the intermediate casing2, which provides the first member6increased mechanical strength. It goes without saying, however, that the first member6could be independent of the intermediate casing2and mounted as an insert. The first member6could also be made of a different material from that of the intermediate casing2. The structural characteristics of the second member7are described below before describing its cooperation with the first member6. According to a first embodiment, with reference toFIG.8representing a close-up view A5ofFIG.6, the second member extends in a plane transverse to the axis X. Preferably, the second member7has a U-shape defining two side branches77-1,77-2and a base71. The concavity of the U is radially inwardly oriented so as to allow the retaining annulus34to expand radially outwards due to thermal conditions. As represented inFIG.8, the retaining annulus34comprises an upstream annular ring340and the second member7is formed in the upstream annular ring340. The upstream annular ring340extends transversely to the axis X as illustrated inFIG.8. According to this embodiment, the second member7is in the form of a housing formed in the upstream annular ring340. Preferably, the legs77-1,77-2extend protruding from the internal edge341of the upstream annular ring340to facilitate cooperation with the first member6and improve tangential blocking. In this example, the second member7forms a one-piece assembly with the retaining annulus34. In other words, the second member7is made of the material of the retaining annulus34, which provides the second member7increased mechanical strength. It goes without saying that the second member7could be independent of the retaining annulus34. The second member7could also be of a different material from that of the retaining annulus34. As illustrated inFIG.9A, the second member7is configured to receive the first member6by interlocking the first member6into the housing formed by the second member7. In other words, the base71is configured to cooperate with the external face61of the first member6. Furthermore, the side branches77-1,77-2of the second member7are configured to cooperate with the side faces63-1,63-3of the first member6so as to block any tangential movement. Conversely, the retaining annulus34is free to expand radially and move axially with respect to the internal shell21of the intermediate casing2. Advantageously, there is no hyperstatic connection. Preferably, as illustrated inFIGS.8and9A, the second member7has a total radial height H7substantially equal to the total radial height H6of the first member6. Furthermore, the second member7has a tangential width L73defined as the tangential length separating the two legs77-1,77-2substantially equal to the tangential length L63of the first member6. Furthermore, the second member7has an axial thickness E7preferably less than the axial thickness E63of the first member6, preferably equal to the foot axial thickness E64of the first member6, so as to allow total interlocking in the axial direction X1 of the first member6with the second member7. Such an interlocking connection is also known as a dog connection. Preferably, as illustrated inFIGS.8and9A, the second member7comprises beveled faces72-1,72-2connecting the base71to the side legs77-1,77-2, configured to cooperate with the head side faces62-1,62-3of the first member6. This thus allows radial centering of the first member6relative to the second member7during radial movements. Preferably also, the second member7comprises beveled faces74-1,74-2at the internal end of the legs77-1,77-2which are configured to cooperate with the foot side faces64-1,64-3of the first member6. With reference toFIG.9Brepresenting a close-up view A3ofFIG.4, to mount the previously set forth compressor1, the inlet guide wheel33of the high pressure compressor3is axially mounted to the intermediate casing2such that each first member6is axially inserted by axial movement D into each second member7between the legs77-1,77-2. As a result of the mounting, the retaining annulus34is prevented from rotating about the axis X but remains free to move axially along the axis X or to expand radially. In case of ingestion of a foreign body, such as a bird, the latter may strike the retaining annulus34, which transmits mechanical loads to the internal shell21by virtue of the blocking device5. In other words, the retaining annulus34does not move tangentially, thus avoiding any loss of vane38. Two further embodiments of the second member7are described hereafter with reference toFIGS.10A and10B. According to another embodiment of the invention, as illustrated inFIG.10A, the second member7comprises two portions78-1,78-2extending axially protruding upstream from the retaining annulus34, in particular, from the upstream annular ring340. Preferably also, the portions78-1,78-2are separated from each other at least by the tangential length L73. In other words, the tangential space formed between portions78-1,78-2defines a housing for receiving the first member6. According to one aspect of the invention, the two portions78-1,78-2are configured to extend on either side tangentially from the first member6, so as to form a tangential stop for the first member6in each direction of rotation about the axis X (bidirectional stop). According to another embodiment of the invention, the second member7comprises a single portion78-1,78-2, configured to extend tangentially from a single side of the first member6. This second member7thus forms a unidirectional tangential stop for the first member6, the first member6being tangentially blocked along a single direction of rotation. As illustrated inFIG.10B, the blocking device5comprises at least two second members7to allow bidirectional tangential blocking. As illustrated inFIG.10B, a second member7ais configured to halt a motion along the first direction of rotation B1by cooperation with a first member6(not represented). Another second member7bis configured to halt a motion along the second direction of rotation B2by cooperation with another first member6(not represented). Blocking is thus bidirectional. By virtue of the blocking device of the compressor according to the invention, the vanes38of the inlet guide wheel33are protected upon ingestion of foreign bodies into the compressor1. More precisely, the blocking device5tangentially blocks the inlet guide wheel33with respect to the intermediate casing2, which makes it possible to avoid the appearance of a mechanical moment about the axis X when the foreign body strikes the inlet guide wheel33. This blocking device5is also space-saving and does not require any changes to the overall structure of the inlet guide wheel33and the intermediate casing2. The existing assembly line of the inlet guide wheel33and the intermediate casing2can therefore advantageously be kept. Furthermore, the blocking device5allows an axial and radial movement of the inlet guide wheel33with respect to the intermediate casing2, so that the performance of the turboshaft engine100is not reduced by friction. | 19,915 |
11859509 | DETAILED DESCRIPTION Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “upstream” and “downstream” refer to the relative flow direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the flow direction from which the fluid flows, and “downstream” refers to the flow direction to which the fluid flows. Referring now to the drawings,FIG.1illustrates a cross-sectional view of one embodiment of a turbofan gas turbine engine10(“turbofan10”) for use in an aircraft in accordance with the embodiments disclosed herein. The turbofan10includes a longitudinal or axial centerline axis12extending therethrough for reference purposes. In general, the turbofan10may include a core gas turbine engine14and a fan section16positioned upstream thereof. The core engine14may generally include a substantially tubular outer casing18that defines an annular inlet20. In addition, the outer casing18may further enclose and support a low pressure compressor section22for increasing the pressure of the air that enters the core engine14to a first pressure level. A high pressure, multi-stage, axial-flow compressor section24may then receive the pressurized air from the low pressure compressor section22and further increase the pressure of such air. The pressurized air exiting the high-pressure compressor section24may then flow to a combustor26within which fuel is injected into the flow of pressurized air, with the resulting mixture being combusted within the combustor26. The high energy combustion products are directed from the combustor26along the hot gas path of the turbofan10to a high pressure turbine section28for driving the high pressure compressor section24via a high pressure shaft30, and then to a low pressure turbine section32for driving the low pressure compressor section22and fan section16via a low pressure shaft34generally coaxial with high pressure shaft30. After driving each of turbine sections28and32, the combustion products may be expelled from the core engine14via an exhaust section35to provide propulsive jet thrust. Additionally, as shown inFIG.1, the fan section16of the turbofan10may generally include a rotatable, axial-flow fan rotor assembly38surrounded by an annular fan casing40. It should be appreciated by those of ordinary skill in the art that the fan casing40may be supported relative to the core engine14by a plurality of substantially radially-extending, circumferentially-spaced outlet guide vanes42. As such, the fan casing40may enclose the fan rotor assembly38and its corresponding fan rotor blades44. Moreover, a downstream section46of the fan casing40may extend over an outer portion of the core engine14so as to define a secondary, or by-pass, airflow conduit48providing additional propulsive jet thrust. In several embodiments, the low pressure shaft34may be directly coupled to the fan rotor assembly38to provide a direct-drive configuration. Alternatively, the low pressure shaft34may be coupled to the fan rotor assembly38via a speed reduction device37(e.g., a reduction gear or gearbox) to provide an indirect-drive or geared drive configuration. Such a speed reduction device(s) may also be provided between any other suitable shafts and/or spools within the engine as desired or required. FIG.2is a schematic view of the low pressure turbine section32and the exhaust section35. More specifically, the low pressure turbine section32includes a plurality of stator vanes70and a plurality of turbine blades72. AlthoughFIG.2shows three stator vanes70and two turbine blades72, the low pressure turbine section32may include more or less stator vanes70and more or less turbine blades72as is needed or desired. As the combustion products60flow through the low pressure turbine32, the stator vanes70direct the combustion products60onto the turbine blades72. The turbine blades72extract kinetic energy from the combustion products60, thereby rotating the low pressure shaft34. After flowing through the low pressure turbine32, the combustion products exit the turbofan10through the exhaust section35as mentioned above. The exhaust section35may include a center body62and an exhaust nozzle36positioned circumferentially around and radially spaced apart from the center body62. In this respect, the center body62and the exhaust nozzle36define an annular exhaust conduit76through which the combustion products60flow. In some embodiments, the center body62may include a forward center body64and an aft center body66, which may be coupled via one or more attachment assemblies100. Preferably, the center body62has a generally conical shape; although, the center body62may be any suitable shape. The aft center body66or the center body62(if the center body62is a single piece) may couple to a turbine rear frame68via one or more attachment assemblies100. The turbine rear frame68provides structural support for some of the components (e.g., the stator vanes70) of the low pressure turbine32. In this respect, the turbine rear frame68also supports the center body62. Nevertheless, however, the center body62may connect to other portions of the turbofan10. Referring again toFIG.1, during operation of the turbofan10, it should be appreciated that an initial air flow (indicated by arrow50) may enter the turbofan10through an associated inlet52of the fan casing40. The air flow50then passes through the fan blades44and splits into a first compressed air flow (indicated by arrow54), which flows through conduit48, and a second compressed air flow (indicated by arrow56), which enters the low pressure compressor section22. The pressure of the second compressed air flow56is then increased and enters the high pressure compressor section24(as indicated by arrow58). After mixing with fuel and being combusted within the combustor26, combustion products60exit the combustor26and flow through the high pressure turbine section28. Thereafter, the combustion products60flow through the low pressure turbine section32and exit the exhaust nozzle36to provide thrust for the engine10. Along with a turbofan10, a core turbine14serves a similar purpose and sees a similar environment in land-based gas turbines, turbojet engines in which the ratio of the first portion of air54to the second portion of air56is less than that of a turbofan, and unducted fan engines in which the fan section16is devoid of the annular fan casing40. FIGS.3-6illustrate one embodiment of the attachment assembly100. More specifically,FIG.3illustrates the alignment of a turbine rear frame aperture106with a forward center body aperture112, which permits receipt of the attachment assembly100.FIG.4illustrates the attachment assembly100coupling the turbine rear frame68and the forward center body64.FIG.5illustrates an insert120of the attachment assembly100, andFIG.6illustrates a bushing122of the attachment assembly100. As illustrated inFIGS.3-8, the attachment assembly100defines an axial direction90and a radial direction92. The attachment assembly100secures a first component, such as the turbine rear frame68of the turbofan10, to a second component, such as the forward center body64of the turbofan10. In some embodiments, the first and the second components may be gas turbine walls. Although, the first and second components may be any other adjacent components in the turbofan10. In some embodiments, the forward center body64may be constructed from a CMC material or another suitable composite material. In this respect, the forward center body64may include a plurality of plies186(FIG.3) as will be discussed in greater detail below. Conversely, the turbine rear frame68may be constructed from a metallic material such as a nickel-based superalloy. Although, the forward center body64and the turbine rear frame68may be constructed from any suitable material. FIG.3illustrates the portions of the forward center body64and the turbine rear frame68coupled by the attachment assembly100. More specifically, the turbine rear frame68defines the turbine rear frame aperture106, which extends between a first surface102and a second surface104. In a similar manner, the forward center body64defines the forward center body aperture112, which extends between a first surface108and a second surface110and has a forward center body diameter218. The forward center body64also defines a cavity or depression114in the first surface108positioned circumferentially around the forward center body aperture112for accommodating the insert120as will be discussed in greater detail below. An annular boss116extends radially outward from the second surface110of the forward center body64and is positioned circumferentially around the forward center body aperture112. The forward center body64and the turbine rear frame68may at least partially overlap and may be axially spaced apart by an axial gap118. Preferably, the turbine rear frame aperture106and forward center body aperture112are radially aligned (i.e., concentric), but may be radially offset as well. The turbine rear frame aperture106may include a plurality of threads188. FIG.4illustrates the various components of the attachment assembly100as well as the positioning of each with respect to the forward center body64and the turbine rear frame68. As illustrated inFIGS.4and5, the attachment assembly100includes the insert120having an insert annular wall138. The insert annular wall138includes an insert annular wall length172and extends in the axial direction90. The insert annular wall138defines an insert aperture150extending therethrough. In this respect, the insert annular wall138includes a radially outer surface142and a radially inner surface144. As such, the insert annular wall138includes an inner diameter202and an outer diameter200. Preferably, the entirety of the radially inner surface144includes a plurality of threads190as illustrated inFIG.5. Although, only a portion of the radially inner surface144may include the plurality of threads190. The insert120also includes an insert flange140extending radially outwardly from the insert annular wall138. The insert flange140includes a first surface146, a second surface148, a radially outer surface192, and an insert flange diameter170. Preferably, the insert flange diameter170is greater than the forward center body aperture diameter218. For example, the insert flange diameter170may be about 1.5 times to 5 times longer than the forward center body aperture diameter218. Alternately, the insert flange diameter170may be about 1.5 times to 3 times longer than the forward center body aperture diameter218. If the diameter218of the forward center body aperture112varies in the radial direction92, the smallest of the forward center body aperture diameters218is used to define the insert flange diameter170. Although, the insert flange diameter170may be relatively shorter than or the same as the insert annular wall length172. The radially outer surface192of the insert flange140includes a radially outer radius or fillet154. The radially outer radius154is between 0.05 inches (i.e., 50 mils) and 0.5 inches (i.e., 500 mils); although, the radially outer radius154may have any suitable dimensions. Furthermore, the insert flange140includes a radially inner radius or fillet152between the insert annular wall138and the insert flange140. Specifically, the radially inner radius152is positioned between the radially outer surface142and the first surface146. The radially inner radius152is at least 0.05 inches (i.e., 50 mils), but less than the length172of the insert annular wall138. Although, the radially inner radius152may have any suitable dimensions. As illustrated inFIGS.4and6, the attachment assembly100also includes the bushing122. The bushing122includes a bushing annular wall158and a bushing flange156extending radially outward from the bushing annular wall158. The bushing annular wall158defines a bushing aperture168extending therethrough. In this respect, the bushing annular wall158includes a radially outer surface164and a radially inner surface166. Preferably, the entirety of the radially outer surface164includes a plurality of threads194as illustrated inFIG.6. Although, only a portion of the radially outer surface164may include the plurality of threads194. The bushing annular wall158includes an inner diameter198and an outer diameter196. The outer diameter196should be sized to permit the bushing annular wall158to fit in the insert aperture150. The bushing flange156includes a first surface160and a second surface162. The attachment assembly100further includes a fastener124illustrated inFIG.4. The fastener124may include a head132and a shank204extending axially outward from the head132. In one embodiment, the shank204includes a smooth portion208and a threaded portion206. Although, the shank204may be entirely smooth or threaded. In this respect, the fastener124is preferably bolt-like. Nevertheless, any suitable type of fastener may be used. When the attachment assembly100couples the forward center body64and the turbine rear frame68, the insert annular wall138is positioned in the forward center body aperture112and the insert flange140is positioned in the cavity114. As will be discussed in greater detail below, the cavity114is formed by layering the plies186over the insert flange140and co-curing the plies186and the insert120. In some embodiments, the plies186and the insert flange140may be co-sintered as well. In certain embodiments, a backer washer130may be positioned on the second surface110of the forward center body64circumferentially around and radially outward from the annular boss116. The bushing annular wall158is positioned in the insert aperture150. In this respect, the bushing annular wall158and the insert annular wall138may be threadingly coupled if the radially outer surface164of bushing annular wall158includes the threads194and the radially inner surface144of the insert annular wall138includes the threads190. Although, the bushing annular wall158and the insert annular wall138may be coupled in any suitable manner (e.g., press-fit, tack-welded, snap-fit, swaged, etc.). As illustrated inFIG.4, the bushing122is oriented such that the bushing flange156and the insert flange140are positioned on the opposite sides of the forward center body64. A spring washer or Belleville spring126is positioned between the backer washer130and the bushing flange122. If no backer washer130is present, the spring washer126is positioned between the bushing flange156and the second surface110of the forward center body64. The spring washer126exerts axially outward force on the backer washer130or the second surface110and the bushing flange156. This force presses the insert flange140against the first surface108of the forward center body64(i.e., the cavity114), thereby securing the insert120and the bushing122to the forward center body64. Alternately, a coil spring (not shown) may exert the aforementioned axially outward force. The fastener124extends through the bushing aperture168to couple with the turbine rear frame68. More specifically, the smooth portion208of the shank204may be positioned in the bushing aperture168, and the threaded portion206of the shank204may couple to the turbine rear frame68. Alternately, the fastener124may threadingly engage the bushing annular wall158in some embodiments. In this respect, the fastener124is at least partially received by the turbine rear frame aperture106, the second aperture112, the insert aperture150, and the bushing aperture168. In further alternate embodiments, the smooth portion208of the shank204may extend through the turbine rear frame aperture106and be secured by a nut (not shown) in contact with the first surface102of the turbine rear frame68. After installation, the head132of the fastener124is preferably axially spaced apart from the first surface160of the bushing flange156by an axial gap136to permit thermal expansion between the various components of the attachment assembly100. In the embodiment shown inFIG.4, the threaded portion206threadingly couples with a collar128, which is positioned in the turbine rear frame aperture106and threadingly couples with the turbine rear frame68. Alternately, the threaded portion206may threadingly couple directly to the turbine rear frame64. In some embodiments, the attachment assembly100may include a leaf seal134positioned in the axial gap118. In this respect, the leaf seal134extends between the second surface104of the turbine rear frame68and the second surface148of the insert flange140. The leaf seal134may also contact the first surface108of the forward center body64instead of or in addition to the second surface148of the insert flange140. Although, some embodiments of the attachment assembly100may not include the leaf seal134. As mentioned above, the forward center body64is preferably constructed from a CMC material or another suitable composite material. For example, the CMC material is preferably an oxide-oxide (e.g., oxide fibers in a silicone matrix) CMC material. Although, a polymeric matrix composite or other suitable composite material may be used. The turbine rear frame68, the insert120, the bushing122, the fastener124, the spring washer126, the collar128, and/or the backer washer130are constructed from metallic materials such, including superalloy metals such as nickel-based superalloys, cobalt-based superalloys, etc. Although, the turbine rear frame68, the insert120, the bushing122, the fastener124, the spring washer126, the collar128, and/or the backer washer130may be constructed from any suitable material. FIGS.7and8illustrate an alternate embodiment of the attachment assembly100′. More specifically,FIG.7illustrates the alignment of the forward center body aperture112with an aft center body aperture180, which permits mounting of the attachment assembly100′.FIG.8illustrates the attachment assembly100′ coupling the forward center body64and the aft center body66. The attachment assembly100′ secures a first component, such as the forward center body64of the turbofan10, to a second component, such as the aft center body66of the turbofan10. Like the attachment assembly100, the first and second components may be any other adjacent stationary components in the turbofan10. In some embodiments, the forward center body64and the aft center body66may be constructed from a CMC material or another suitable composite material. In this respect, the forward center body64and the aft center body66may include a plurality of plies186(FIG.7) as will be discussed in greater detail below. Although, the forward center body64and the aft center body66may be constructed from any suitable material. FIG.7illustrates the portions of the forward center body64and the aft center body66coupled by the attachment assembly100′. The features of the forward center body64are discussed in detail above with respect toFIG.3. The aft center body66defines the aft center body aperture180, which extends between a first surface174and a second surface176and has an aft center body diameter220. The aft center body66also defines a cavity or depression178in the first surface174positioned circumferentially around the aft center body aperture180for accommodating an insert120bas will be discussed in greater detail below. An annular boss184extends radially outward from the second surface176of the aft center body66and is positioned circumferentially around the aft center body aperture180. The forward center body64and the aft center body66at least partially overlap and may be axially spaced apart by an axial gap182. Preferably, the forward center body aperture112and the aft center body aperture180are axially aligned (i.e., concentric), but the forward center body aperture112and the aft center body aperture180may be axially offset as well. As illustrated inFIG.8, the attachment assembly100′ includes a pair of inserts120a,120b; a pair of bushings122a,122b; a pair of spring washers126a,126b; and a single fastener124. More specifically, the insert120aand the spring washer126aare substantially identical to the insert120and the spring washer126described above in greater detail. The bushing122ais substantially identical to the bushing122, except that the radially inner surface166of the bushing annular wall158includes a plurality of threads210, which may threadingly couple to the threaded portion206of the fastener124. The first insert120a, the first bushing122a, and the first spring washer126acouple to the forward center body64in the same manner as the insert120, the bushing122, the spring washer126as discussed in greater detail above. In some embodiments, a first backer washer130a, which is substantially identical to the backer washer130, may be positioned between the second surface110of the forward center body64and the spring washer126a. With respect to the aft center body66, the bushing122band the spring washer126bare substantially identical to the bushing122and the spring washer126described above in greater detail. The insert120bis substantially identical to the insert120, except that the radially inner surface144includes a threaded portion214having the plurality of threads190and a smooth portion212. Furthermore, the smooth portion212defines a cavity216positioned circumferentially around the insert aperture150to provide clearance for the head132of the fastener124. The second insert120b, the second bushing122b, and the second spring washer126bcouple to the aft center body66in the same manner as the insert120, the bushing122, the spring washer126couple to the forward center body64as discussed in greater detail above. In some embodiments, a second backer washer130b, which is substantially identical to the backer washer130, may be positioned between the second surface176of the aft center body66and the second spring washer126b. The fastener124couples the forward center body64and the aft center body66. More specifically, the smooth portion208of the shank204is positioned in the bushing aperture168of the second bushing122b, and the threaded portion206of the shank204is positioned in the bushing aperture168of the first bushing122a. As such, the threaded portion206of the shank204threadingly couples to the inner wall166of the first bushing122a. In this respect, the fastener124is received by the forward center body aperture112; the aft center body aperture180; the insert apertures150of the first and second inserts120a,120b; and the bushing apertures168of the first and second bushing122a,122b. The head132of the fastener124is positioned in the cavity216. The first surface108of the forward center body64and second surface176of the aft center body66may be axially spaced apart by the axial gap182to provide clearance for the second insert120b, the second bushing122b, and the second spring washer126b. In some embodiments, the turbine rear frame68, the forward center body64, and/or and the aft center body66may include multiple apertures106,112,180and/or multiple cavities114,178circumferentially spaced apart from each other. In this respect, the turbine rear frame68and the forward center body64and/or the forward center body64and the aft center body66may be coupled with multiple circumferentially spaced apart attachment assemblies100,100′. FIG.9is a flow chart illustrating a method (300) for forming the attachment assembly100,100′ in accordance with the embodiments disclosed herein. The method (300) is described below in the context of coupling the forward center body64to the turbine rear frame68. Although, the method300may be used in the context of coupling the forward center body64to the aft center body66or, more generally, coupling any composite component in the turbofan10to any other component in the turbofan10. In step (302), a plurality of resin-impregnated plies, such as the plies186, are layered over the insert flange140of the insert120to form a composite component, such as the forward center body64. As discussed above, the plies186are preferably oxide-oxide CMC plies, but may be any type of suitable composite plies. Specifically, a portion of the plurality of plies186curves around the radially outer radius154and are positioned on the first surface146of the insert flange140. In this respect, the cavity114is formed in the forward center body64to accommodate the insert flange140. The insert annular wall138extends through the forward center body64, thereby forming the forward center body aperture112. That is, the plies186do not cover the insert annular wall138. Instead, the plies186curve upwardly when in contact with the radially outer surface142of the insert annular wall138to form the annular boss116. As mentioned above, the forward center body64may include as many or as few plies186as is necessary or desired. In step (304), the plies186are initially in the wet state. During the cure process of step (304), the polymeric resins in the wet plies react to yield a composite with a cured matrix. Step (304) may be repeated for a second composite component (e.g., the aft center body66) if multiple composite components are being coupled by the attachment assembly100,100′. Other processes for forming the forward center body64(e.g., braiding, filament winding, etc.) may be used as well. In step (304), the forward center body64, which is in the wet state, and the insert120are co-cured (i.e., cured together and at the same time). Typically, an autoclave is used for the curing in step (304). After step (304), the forward center body64is in the green state. In step (306), the forward center body64and the insert120are placed in a sintering furnace (not shown) and co-sintered (i.e., sintered together and at the same time). Step (306) may be omitted if the forward center body64is formed from polymeric matrix composite plies. The steps (304) and (306) effectively couple the forward center body64and the insert120. That is, the insert flange140and a portion of the insert annular wall138are bonded to the first surface108of the forward center body64. The radially outer fillet154prevents cracking of the forward center body64when the co-cured and co-sintered with the insert120due to the disparate thermal expansion coefficients of the composite forward center body64and the metallic insert120. Nevertheless, this coupling may not be strong enough for carrying loads exerted on the forward center body64. In this respect, the bushing122and the spring washer126may be installed to strengthen this coupling. More specifically, the spring washer126is positioned circumferentially around the forward center body aperture112and the annular boss116in step (308). In step (310), the bushing122is threading coupled to the insert120. As discussed in greater detail above, the spring washer126exerts axially outward force on the forward center body64and the bushing flange156, which secures the insert120to the forward center body64. In some embodiments, the backer washer130is positioned between the spring washer126and the forward center body64. Method (300) may include other steps as well. For example, the fastener124may be positioned in the bushing aperture168to couple the forward center body64to a metallic wall, such as the turbine rear frame68, or another composite wall, such as the aft center body66. This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. | 28,468 |
11859510 | DETAILED DESCRIPTION OF INVENTION The description and the figures present only exemplary embodiments of the invention, which may also be combined with each other in any manner in order to achieve further advantages. FIG.1shows a top view of a turbine blade tip3of a turbine blade1. A leading edge7and a trailing edge10of a blade4of the turbine blade1are shown. The blade tip3has a wall19, which extends along the outer contour of the blade4. The wall19extends on a preferably flat or planar surface28of the turbine blade1. As viewed in the radial direction14(direction of installation of the turbine blade1in the turbine), the wall19preferably has the same thickness at every point. Preferably, the wall19also has the same height throughout, as viewed from the surface28. Such curves and geometries of the wall19are known from the prior art. Within a recess20formed by the wall19, in the main body of the turbine blade1there is preferably at least one, in particular at least two, cooling air holes18, from which cooling air flows out of the surface28. Preferably there are two or three cooling air holes18. The cooling air holes18are preferably arranged close to the leading edge7and in the longitudinal direction (=from the leading edge7in the direction of the trailing edge10) or in the direction of flow around the turbine blade1, as viewed when in use, preferably in front of an inflow housing22. In the case of a plurality of cooling air holes18, these are preferably arranged in succession in the longitudinal direction of the turbine blade1. Within the recess20, there is preferably an inflow housing22covering supply air channels32(FIGS.4,5) from the interior35of the turbine blade1, such that cooling air can be introduced into a channel40in the wall19(FIG.5). In particular, there are at least three supply air channels32. Preferably, there is also only one channel40in the wall19. The inflow housing22is arranged on the surface28inside the recess20, and directly adjoins the wall19directly. This inflow housing22is preferably realized on the suction side13, which is opposite to the pressure side16. The inflow housing22is preferably not as high as the wall19. The inflow housing22is realized so as to be just long enough to cover the supply air channels32(FIG.5). The inflow housing22is preferably located behind the last cooling air hole18, as viewed in the longitudinal direction. FIG.2shows a top view of the turbine blade tip3. On its outermost surface21on the suction side13, the wall19has outlets of a plurality of cooling holes25, here in particular ten, from which cooling air flows out of the channel40(FIGS.5,6) of the wall19, through the wall19to the outside. The cooling holes25are arranged in succession in the longitudinal direction of the turbine blade tip3and preferably offset from one another. There are preferably at least three of these cooling holes25, very preferably at least five. The cooling air supply to the cooling holes25is effected via a cooling air channel40(FIGS.5,6), in particular only through the one cooling air channel40. On the pressure side16, there are preferably no holes realized in the wall19. FIG.3shows an exemplary initial situation in the production of such a turbine blade tip3. The turbine blade1is produced with a preferably flat or planar surface28, or is provided, or reworked after use, which preferably then already has the cooling air holes18, which are arranged within the region of the recess20, as well as further, in particular five, supply air channels32, from which cooling air can flow from the interior35(FIGS.4,5) of the turbine blade1into the channel40within the wall19. Such a turbine blade1may be produced at the time of production of a new blade or during the repair according toFIG.3. The cooling air holes18are newly made, or are already present or are partially closed because the cooling of the blade tip3has been improved. In particular, the last cooling air hole18, as viewed in the direction of circumflow. Likewise, the entire turbine blade1, with the blade tip3, may be wholly produced together in an additive method. Likewise, the blade tip3may be applied to the surface28by means of SLM, SLS, overlay welding or any other additive manufacturing method. It is likewise possible to produce the blade tip3separately (FIG.6) and connect it to the turbine blade1as shown inFIG.3. FIG.4shows a section according toFIG.3with the surface28and the supply air channels32, which are supplied via the interior35, in particular from a deflection channel (the interior35), within the turbine blade1. The supply air channels32preferably extend at an angle α of 90°>α>0°, in particular 80°≥α≥5° to the radial direction14. FIG.5shows a section through a structure of a blade tip3according to the invention. The blade tip3may include a part of the interior35or may be realized only from the surface28(FIG.6). The suction side13and pressure side16, and an interior35or deflection channel35of an internal cooling structure of the turbine blade1can be seen in the blade4. On the inside, the wall19in cross-section has the channel40, into which cooling air flows from the supply air channels32. The channel40then distributes the cooling air to the outside via the preferably ten cooling air holes25. Preferably, all of the cooling air for the wall19flows from preferably all of the supply air channels32into the preferably single channel40, and then preferably to the outside through the wall19, through all of the cooling holes25. The channel40has a triangle-like shape in cross-section, which is rounded at the upper end. As a result, the channel40has a greater width at the level of the surface28than at the radial end as viewed in the radial direction14. The channel40is preferably realized so as to be wider at the level of the surface28than the diameter of the supply air channels. The channel40is thus delimited in cross-section by the surface28of the turbine blade1and the wall19, and is also formed by the inflow housing22. The opposite part of the wall19on the pressure side16preferably has no channel in the wall and also no cooling air holes. Different materials may be used for the blade tip3and the blade4. Likewise, there are preferably no holes exiting on the blade side13,16near the blade tip. Such structures can be produced by additive manufacturing methods, such as, in particular, selective laser melting. This can be effected during production of a new blade or during repair. | 6,493 |
11859511 | DETAILED DESCRIPTION In a first example, a dual-wall airfoil may comprise a spar. The spar has a chord axis and a span axis. The dual-wall airfoil comprises a coversheet on the spar and a dual feed circuit between the spar and the coversheet. The dual feed circuit includes a first dam, a second dam spaced apart from the first dam along the chord axis of the spar, a first inlet disposed adjacent to the first dam, a second inlet disposed adjacent to the second dam, a circuit outlet disposed between the first inlet and the second inlet, and diamond and/or hexangular pedestals disposed on an outer surface of the spar. The outer surface of the spar faces the coversheet. The diamond and/or hexangular pedestals are located between the first inlet and the second inlet. The diamond and/or hexangular pedestals form multiple cooling channels between the first inlet and the circuit outlet and between the second inlet and the circuit outlet. No other circuit inlets are located between the first inlet and the second inlet. In a second example, a dual-wall airfoil comprises the spar. The spar includes a plurality of internal cavities. The internal cavities include a first cavity disposed at a leading edge of the airfoil, a second cavity disposed at a trailing edge of the airfoil, a third cavity disposed between the first cavity and the second cavity. The spar further comprises the coversheet on the spar and the dual feed circuit disposed between the spar and the coversheet. The dual feed circuit includes the first dam, the second dam, the first inlet disposed adjacent to the first dam, the second inlet disposed adjacent to the second dam, and the circuit outlet disposed between the first inlet and the second inlet. The first inlet connects the first cavity to the dual feed circuit and the second inlet may connect the third cavity to the dual feed circuit. Alternatively or additionally, the first inlet connects the third cavity to the dual feed circuit and the second inlet connects the second cavity to the dual feed circuit. In a third example, a method of cooling the airfoil comprises: supplying a cooling fluid to the first internal cavity of an airfoil spar and the second internal cavity of the airfoil spar. The method comprises directing the cooling fluid from the first internal cavity through the first inlet to a dual feed circuit. The first inlet is immediately adjacent to the first dam of the dual feed circuit. The method comprises directing the cooling fluid from the second internal cavity though the second inlet to the dual feed circuit. The second inlet may be adjacent to the second dam of the dual feed circuit. The method comprises directing the cooling fluid from the first inlet downstream through a plurality of diamond and/or hexangular pedestals and through the circuit outlet. The method comprises directing the cooling fluid from the second inlet upstream through the plurality of diamond and/or hexangular pedestals and through the circuit outlet. The method comprises directing the cooling fluid from the circuit outlet along an outer surface of the airfoil downstream of the circuit outlet. One interesting feature of the systems and methods described below may be that dual feed circuits provide an effective airfoil cooling scheme while using less flow and/or delta pressure as compared to exclusively co-fed or counter-fed circuits. For example, by providing a dual feed circuit, which uses both co and counter flow feeds, the upstream side of the circuit is cooled using a co-fed heat exchanger while the downstream side of the circuit is fed using a counter-fed heat exchanger. The two inlets for the dual feed circuit (one upstream and one downstream of the outlet) and lower sink pressure (of the downstream inlet versus the upstream inlet) raises the pressure difference in the dual feed circuit to drive more coolant than an exclusively counter-fed circuit. Alternatively, or in addition, by having the dual feed supply an outlet positioned between the two inlets, the downstream portion of the circuit also benefits from film cooling as cooling fluid exits the outlet. Alternatively, or in addition, an interesting feature of the systems and methods described below may be that by having two inlets, or two rows of inlets each disposed on an opposite end of the circuit, the inlet holes can be larger to mitigate blockage risk and to ensure adequate film coverage downstream of the outlet. Alternatively, or in addition, dual feed circuits may be used in areas where there is a relatively high exit pressure, for example, on the pressure side and/or near the leading edge, in order to provide adequate cooling efficiently. Alternatively, or in addition, dual feed circuits allow for more flexibility in packaging the circuit on the airfoil, as the circuit inlets can be positioned independent from the circuit outlet to avoid internal ribs of the spar. FIG.1illustrates an example of an airfoil100. The airfoil100may include a spar102, a coversheet104, an internal cavity106, a pressure side108, a suction side110, a leading edge112, a trailing edge114, a chord axis116, a heat exchanging circuit118, a circuit inlet120, and/or a circuit outlet122. The leading edge112may be any point at the front of the airfoil100. The airfoil100is designed to have a fluid flow126, such as a flow of hot gases exiting a combustor of a gas turbine engine, flow around the airfoil100. The front of the airfoil100may be considered the side of the airfoil100facing into the fluid flow126. Alternatively, or additionally, the leading edge112may be the most upstream edge of the airfoil100. Upstream refers to a direction opposite of the direction of the fluid flow126. Alternatively or in addition, the leading edge112may be at a stagnation point, which is where a flow velocity of the fluid flow126is reduced to zero. The trailing edge114may be at the back of the airfoil100. The back of the airfoil100may be the side of the airfoil opposite of the front and/or opposite of the leading edge of the airfoil100. The trailing edge114may be the most downstream edge of the airfoil100. Downstream refers to the direction of the fluid flow126. The leading edge112may be opposite the trailing edge114. The pressure side108of the airfoil100is a side designed to have a comparatively higher static pressure than the suction side110in the presence of the fluid flow126so as to contribute to a lift force generated by the airfoil100. The pressure side108may extend from the leading edge112to the trailing edge114of the airfoil100. The suction side110may extend from the leading edge112to the trailing edge114of the airfoil100on a side that is opposite of the pressure side108. The chord axis116may extend along the chord-wise length of the airfoil100, in some examples connecting the leading edge112and the trailing edge114. The spar102may form an inner structure of the airfoil100. For example, the spar102may form an inner wall of the airfoil100and one or more internal cavities106of the airfoil100. One or more internal ribs124may separate multiple internal cavities106. The coversheet104may form an outer wall of the airfoil100. The coversheet104may surround and/or encompass the spar102. The heat exchanging circuit118may be disposed in between the spar102and the coversheet104. Multiple heat exchanging circuits118may be disposed between the spar102and coversheet104. The heat exchanging circuits118may be located around the circumference of the spar102. Each heat exchanging circuit118may include a circuit inlet120and a circuit outlet122. The circuit inlet120may connect the heat exchanging circuit118to an internal cavity106so that the internal cavity106is in fluid communication with the heat exchanging circuit. The circuit outlet122may connect the heat exchanging circuit118to a flow of fluid external to the airfoil100so that the heat exchanging circuit118is in fluid communication with a fluid flowing126over and/or around the airfoil100and/or the outer surface of the coversheet104. The airfoil100is a dual wall airfoil, wherein the coversheet104is the outer wall and the spar102is the inner wall. The airfoil100may be part of a gas turbine engine, for example, the airfoil100may be a blade and/or vane of the gas turbine engine. The gas turbine engine may be configured to supply power to and/or provide propulsion for an aircraft. Examples of the aircraft may include a helicopter, an airplane, an unmanned space vehicle, a fixed wing vehicle, a variable wing vehicle, a rotary wing vehicle, an unmanned combat aerial vehicle, a tailless aircraft, a hover craft, and any other airborne and/or extraterrestrial (spacecraft) vehicle. Alternatively, or in addition, the gas turbine engine may be utilized in a configuration unrelated to an aircraft such as, for example, an industrial application, an energy application, a power plant, a pumping set, a marine application (for example, for naval propulsion), a weapon system, a security system, a perimeter defense or security system. The spar102may be any structure that extends along a span axis (shown inFIG.3) of the airfoil100and through the center of the airfoil100. The spar102may comprise any rigid structural material, for example, a metal and/or a composite material. The internal cavities106may extend inside the spar102along the span axis. The spar102may include a single internal cavity106or multiple internal cavities106. In some examples, the internal cavities106may be divided by internal ribs124into an upstream internal cavity106at the front of the airfoil100, a downstream internal cavity106at the back of the airfoil100, and/or one or more central internal cavities106disposed between the upstream and downstream internal cavities106. The number of internal cavities106may vary. For example, the spar102may have as few as one single internal cavity106or as many as six internal cavities106. A dual-feed circuit may be fed by one or two internal cavities106. The internal cavities106feeding the dual-feed circuit may not be adjacent to each other. For example, two internal cavities106that feed the same dual-feed circuit may have a third internal cavity106disposed between the two internal cavities106, third internal cavity106may not feed the same dual-feed circuit that the other two internal cavities106feed. The coversheet104may be any structure positioned on the spar102that forms an outer layer of the airfoil100. The coversheet104may be made of any material capable of forming an outer surface of the airfoil100, for example, a metal alloy. The heat exchanging circuit118may be formed by the gap and/or space between the outer surface of the spar102and the inner surface of the coversheet104. The heat exchanging circuit118may be a cooling circuit, by which the airfoil100is cooled. The heat exchanging circuit118may include a channel formed between the spar102and the coversheet104. The heat exchanging circuit118may be a dual feed circuit, a counter feed circuit, and/or a co feed circuit. A dual feed circuit may include at least two circuit inlets120and at least one circuit outlet122. The two circuit inlets120may be spaced apart from each other along the chord axis116of the airfoil100, wherein the circuit inlets120are disposed at an opposite ends of the dual feed circuit. For example, a circuit inlet120may be disposed adjacent to an upstream end of the dual feed circuit, or the end of the dual feed circuit closest to the leading edge112of the airfoil100. Another circuit inlet120may be disposed at the downstream end of the dual feed circuit, or the end of the dual feed circuit closest to the trailing edge114of the airfoil100. The circuit outlet122may be disposed between the two circuit inlets120along the chord axis116, for example, at an approximate midpoint of the dual feed circuit along the chord axis116. The airfoil100may comprise one or more dual feed circuits. The dual feed circuit may, for example, be disposed along the pressure side108of the airfoil100and/or near the leading edge112of the airfoil100. Additionally or alternatively the heat exchanging circuits118may be a co-feed and/or a counter-feed circuit. A co-feed circuit may have a circuit inlet120at an upstream end of the co-feed circuit, or the end of the co-feed circuit closest to the leading edge112of the airfoil100. A co-feed circuit may have a circuit outlet122at a downstream end of the co-feed circuit, or the end of the co feed circuit closest to the trailing edge114of the airfoil. A counter-feed circuit may have a circuit inlet120at downstream end of the counter-feed circuit, or the end of the counter-feed circuit closest to the trailing edge114of the airfoil100. A counter-feed circuit may have a circuit outlet122at an upstream end of the counter-feed circuit, or the end of the counter-feed circuit closest to the leading edge112of the airfoil. The airfoil100may include one or more dual feed circuits, co-feed circuits, and/or co-flow circuits around the airfoil100between the spar102and the coversheet104. A dual-feed circuit may, for example, be disposed at a midpoint along the chord axis116of the pressure side108. A co-feed circuit may extend downstream from a downstream end of the dual-feed circuit, towards the trailing edge114, and along the pressure side108of the airfoil100, extending between the dual-feed circuit and the trailing edge114of the airfoil100. For example, the co-feed circuit may extend from the dual-feed circuit to another heat exchanging circuit118that extends to, or covers, the trailing edge114of the airfoil100. Additionally or alternatively, a counter-feed circuit may extend upstream from an upstream end of the dual-feed circuit, towards the leading edge112, and along the pressure side of the airfoil100, extending between the dual-feed circuit and the leading edge112of the airfoil100. For example, the counter-feed circuit may extend from the dual-feed circuit to another heat exchanging circuit118that extends to, or covers, the leading edge112of the airfoil100. The circuit inlets120may be any sort of aperture in the spar102, extending through the spar102wall from an internal cavity106to a heat exchanging circuit118. The circuit inlets120may be, for example, a through-hole formed via machining or casting. The circuit inlets120may be perpendicular to the spar102wall, or may be formed at an acute or obtuse angle with the spar102wall. The circuit outlets122may be any sort of aperture in the coversheet104, extending through the coversheet104from the heat exchanging circuit118and past the outer surface of the coversheet104and/or airfoil100. The circuit outlets122may, for example, be film holes formed at an angle with the coversheet104to direct cooling fluid in a film over the outer surface of the coversheet104and/or airfoil100downstream from the circuit outlet122. During operation, a cooling fluid may flow from a cooling fluid source (not shown) into the internal cavities106. For example, the cooling fluid may flow through a shank of the airfoil100into the internal cavities106. The cooling fluid may come from an upstream component of the turbine engine, for example, bypass air from an upstream compressor. The cooling fluid and the fluid flow126may be the same fluid that originates from upstream and then is split between a cooling fluid flow and the hot fluid flow126. The cooling fluid may flow from the internal cavities106, through the circuit inlets120and into the heat exchanging circuits118. The cooling fluid may flow from the circuit inlets120, through the heat exchanging circuits118, and towards the circuit outlets122. In a dual feed circuit, for example, the cooling fluid may flow through a first internal cavity106, through the circuit inlet120disposed near the end of the dual feed circuit closest to the leading edge112of the airfoil100, flow downstream or towards the trailing edge114of the airfoil100to the circuit outlet122, out the circuit outlet122, and over the surface of the coversheet104downstream from the circuit outlet122. In a dual feed circuit the cooling fluid may also flow through a second internal cavity106, through the circuit inlet120disposed near the end of the dual feed circuit closest to the trailing edge114of the airfoil100, flow upstream or towards the leading edge112of the airfoil100to the circuit outlet122, combine with the cooling fluid flowing from the circuit inlet120closest to the leading edge112of the airfoil100, out the circuit outlet122, and over the surface of the coversheet104downstream from the circuit outlet122. FIG.2illustrates a cross section view of a dual feed circuit200of airfoil100. The dual feed circuit200ofFIG.2may be a heat exchanging circuit118ofFIG.1. The dual feed circuit200may be disposed between the spar102and the coversheet104of the airfoil100. The dual feed circuit200may comprise an upstream circuit inlet202, a downstream circuit inlet204, an upstream dam208, a downstream dam206, and a circuit outlet122. As mentioned above, the terms “upstream” and “downstream” are in reference to the direction that hot gas flows over the outer surface of the coversheet104. The upstream circuit inlet202may include one of the circuit inlets120fromFIG.1and may be disposed adjacent to the upstream dam208, which may be at the end of the dual feed circuit200that is closest to the leading edge112of the airfoil100. The downstream circuit inlet204may be one of the circuit inlets120shown inFIG.1and may be disposed adjacent to the downstream dam206. The downstream dam206may be at the end of the dual feed circuit200closest to the trailing edge114of the airfoil100. The upstream dam208and the downstream dam206may extend between the spar102and the coversheet104along each respective end of the dual feed circuit200so that cooling fluid may only enter or exit the dual feed circuit200from the circuit inlets120,202,204and/or the circuit outlet122. The dams206,208may be made of the same material as the spar102and/or the coversheet104. For example, the dams206,208may be part of a unitary structure with the spar102and/or the coversheet104. Additionally, or alternatively, the dams206,208may be a different material from the spar102and/or the coversheet104. For example, the dams206,208may be a baffle or seal inserted between the spar102and coversheet104. During operation, cooling fluid210may flow from two of the internal cavities106through the upstream circuit inlet202and through the downstream circuit inlet204. Cooling fluid210may flow downstream from the upstream circuit inlet202, through the upstream portion of the dual feed circuit, and out the circuit outlet122. Alternatively or in addition, cooling fluid210may flow upstream from the downstream circuit inlet204, through the downstream portion of the dual feed circuit200, and out the circuit outlet122. Cooling fluid210may flow out the circuit outlet122and form a film of cooling fluid over the outer surface of the coversheet104downstream of the circuit outlet122to cool the outer surface from the flow of hot gas external to the airfoil100. FIG.3illustrates an exploded view of an example of the spar102and of the coversheet104of the dual feed circuit200of the airfoil100. The spar102may comprise a plurality of pedestals300and cooling channels302. The spar102may also comprise a plurality of upstream circuit inlet holes306and downstream circuit inlet holes308. The coversheet104may comprise a plurality of circuit outlets122. The pedestals300may be part of a unitary structure with the spar102. For example, the pedestals300may extend out away from the spar102towards the coversheet104. The pedestals300may contact the coversheet104. For example, the coversheet104may be joined to the spar102at the pedestals300. The pedestal300may, for example, be square, diamond, and/or hexangular in shape and disposed in a repeating pattern. Cooling channels302may be formed in between the pedestals300, spar102, and coversheet104. The upstream circuit inlet202may comprise a plurality of upstream circuit inlet holes306disposed in a row extending along the span axis304of the airfoil100adjacent to the upstream dam208. Additionally or alternatively, the downstream circuit inlet204may comprise a plurality of downstream circuit inlet holes308disposed in a row extending along the span axis304of the airfoil100adjacent to the downstream dam206. The outer surface of the spar102may be unbroken and/or a continuous surface between the upstream circuit inlet holes306and the downstream circuit inlet holes308, meaning, for example, there may be no other circuit inlets, holes, and/or openings on the outer surface of the spar102between the upstream circuit inlet holes306and the downstream circuit inlet holes308along the chord axis116(shown inFIG.1). For example, there may not be any circuit inlets, holes, and/or openings between the pedestals of the dual feed circuit200. The only openings, holes, and/or apertures on the outer surface of the spar and/or pedestals may be the circuit inlet holes306,308. The circuit outlet122may comprise a plurality of circuit outlets122. The plurality of circuit outlets122may be disposed in a single row extending along the span axis304. Additionally, or alternatively, the circuit outlets122may be disposed in parallel rows. The circuit outlets122may be positioned at a midway point between the upstream circuit inlet holes306and the downstream circuit inlet holes308. Additionally, or alternatively, the circuit outlets122may be disposed closer towards the upstream circuit inlet holes306than the downstream circuit inlet holes308. Alternatively, the circuit outlets122may be disposed closer towards the downstream circuit inlet holes308than the upstream circuit inlet holes306. During operation, cooling fluid210may flow through the downstream circuit inlet holes308, upstream through the cooling channels302between the pedestals300, and to the circuit outlets122. Additionally, or alternatively, cooling fluid may flow through the upstream circuit inlet holes306, downstream through the cooling channels302between the pedestals300to the circuit outlets122. FIG.4illustrates an exploded view of an example of the dual feed circuit200of the airfoil100. The spar102may comprise a slot400extending along the span axis304through a row of the pedestals300. The slot400in the pedestals may correspond to a slot circuit outlet402. The slot circuit outlet402may be a circuit outlet122ofFIGS.1-3. The slot400through the pedestals and the slot circuit outlet402may extend along the spar102and the coversheet104, respectively, along the span axis. During operation, the cooling fluid210may flow form the circuit inlets202,204, through the cooling channels302between the pedestals300, through the slot400extending through the pedestals300, and out the slot circuit outlet402. FIG.5illustrates a flow diagram of a method500to cool the airfoil100. The steps may include additional, different, or fewer operations than illustrated inFIG.5. The steps may be executed in a different order than illustrated inFIG.5. During operation cooling fluid210may be supplied to a first internal cavity106of the airfoil100spar102(502). The first internal cavity106may be an upstream and/or leading edge internal cavity106. Additionally or alternatively, may be a central internal cavity106. During operation cooling fluid210may be supplied to a second internal cavity. The second internal cavity106may be a downstream and/or trailing edge internal cavity106. Additionally or alternatively, the second internal cavity106may be a central internal cavity106. The cooling fluid210may be directed from the first internal cavity106through a first inlet120,202to a dual feed circuit118,200(504). The first inlet202may be an upstream circuit inlet202. The first inlet202may be adjacent to a first dam208of the dual feed circuit118,200. The first dam208may be the upstream dam208. The cooling fluid210may be directed from the second internal cavity106though a second inlet120,204to the dual feed circuit118,200(506). The second inlet204may be a downstream circuit inlet204. The second inlet204may be adjacent to a second dam206of the dual feed circuit. The second dam206may be a downstream dam206. The cooling fluid210may be directed from the first inlet202downstream through a plurality of diamond and/or hexangular pedestals300and through a circuit outlet122(508). The cooling fluid201may be directed from the second inlet204upstream through the plurality of diamond and/or hexangular pedestals300and through the circuit outlet122(510). The cooling fluid210may be directed from the circuit outlet122along an outer surface of the airfoil100downstream of the circuit outlet122. Each component may include additional, different, or fewer components. Additionally, or alternatively, the airfoil100may be implemented with additional, different, or fewer components. For example, the airfoil100may include additional or fewer heat exchanging circuits118. The heat exchanging circuits118may include additional dams206,208. The spar102may include additional or fewer internal cavities106and internal ribs124. The heat exchanging circuits118may include fewer or additional pedestals300. The pedestals300may be different or common shapes. The heat exchanging circuits118may include fewer or additional circuit inlets120and/or circuit outlets122. The logic illustrated in the flow diagrams may include additional, different, or fewer operations than illustrated. The operations illustrated may be performed in an order different than illustrated. To clarify the use of and to hereby provide notice to the public, the phrases “at least one of <A>, <B>, . . . and <N>” or “at least one of <A>, <B>, <N>, or combinations thereof” or “<A>, <B>, . . . and/or <N>” are defined by the Applicant in the broadest sense, superseding any other implied definitions hereinbefore or hereinafter unless expressly asserted by the Applicant to the contrary, to mean one or more elements selected from the group comprising A, B, . . . and N. In other words, the phrases mean any combination of one or more of the elements A, B, . . . or N including any one element alone or the one element in combination with one or more of the other elements which may also include, in combination, additional elements not listed. Unless otherwise indicated or the context suggests otherwise, as used herein, “a” or “an” means “at least one” or “one or more.” While various embodiments have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible. Accordingly, the embodiments described herein are examples, not the only possible embodiments and implementations. The subject-matter of the disclosure may also relate, among others, to the following aspects: A first aspect relates to a dual-wall airfoil comprising: a spar having a chord axis and a span axis; a coversheet on the spar; and a dual feed circuit between the spar and the coversheet, the dual feed circuit including a first dam, a second dam spaced apart from the first dam along the chord axis of the spar, a first inlet disposed adjacent to the first dam, a second inlet disposed adjacent to the second dam, a circuit outlet disposed between the first inlet and the second inlet, and a plurality of diamond pedestals disposed on an outer surface of the spar, the outer surface of the spar facing the coversheet, the diamond pedestals located between the first inlet and the second inlet forming a plurality of cooling channels between the first inlet and the circuit outlet and between the second inlet and the circuit outlet, and wherein no other circuit inlets are located between the first inlet and the second inlet. A second aspect relates to the dual-wall airfoil of aspect1wherein the first inlet includes a plurality of first inlets disposed in a row and extending parallel to the first dam, and wherein the second inlet includes a plurality of second inlets disposed in a row and extending parallel to the second dam. A third aspect relates to the dual-wall airfoil of any preceding aspect, wherein the circuit outlet is disposed closer to the second dam than the first dam. A fourth aspect relates to the dual-wall airfoil of any preceding aspect, wherein the circuit outlet is disposed closer to the first dam than the second dam. A fifth aspect relates to the dual-wall airfoil of any preceding aspect, wherein the circuit outlet is a slot. A sixth aspect relates to the dual-wall airfoil of any preceding aspect, wherein the spar further comprises a first internal cavity and a second internal cavity, wherein the first inlet extends through the spar from the first internal cavity to the dual feed circuit and the second inlet extends through the spar from the second internal cavity to the dual feed circuit. A seventh aspect relates to the dual-wall airfoil of any preceding aspect, wherein the first internal cavity is disposed at a leading edge of the spar and the second internal cavity is disposed at a midpoint of the spar, wherein the dual feed circuit is in fluid communication with the first internal cavity at the leading edge of the spar. An eight aspect relates to the dual-wall airfoil of any preceding aspect, wherein the second internal cavity is disposed at a trailing edge of the spar and the first internal cavity is disposed at a midpoint of the spar, wherein the dual feed circuit is in fluid communication with the second internal cavity at the trailing edge of the spar. A ninth aspect relates to the dual-wall airfoil of any preceding aspect, wherein the circuit outlet comprises a plurality of film holes disposed in a row, the row of film holes extending along the span axis of the spar. A tenth aspect relates to the dual-wall airfoil of any preceding aspect, wherein the circuit outlet comprises parallel rows of film holes. An eleventh aspect relates to a dual-wall airfoil comprising: a spar, wherein the spar includes a plurality of internal cavities, the internal cavities including a first cavity disposed at a leading edge of the airfoil, a second cavity disposed at a trailing edge of the airfoil, a third cavity disposed between the first cavity and the second cavity; a coversheet on the spar; and a dual feed circuit disposed between the spar and the coversheet, the dual feed circuit including a first dam, a second dam, a first inlet disposed adjacent to the first dam, a second inlet disposed adjacent to the second dam, and a circuit outlet disposed between the first inlet and the second inlet, wherein the first inlet connects the first cavity to the dual feed circuit and the second inlet connects the third cavity to the dual feed circuit or wherein the first inlet connects the third cavity to the dual feed circuit and the second inlet connects the second cavity to the dual feed circuit. A twelfth aspect relates to the dual-wall airfoil of any preceding aspect, wherein the dual feed circuit is a single dual feed circuit disposed on a pressure side of the airfoil. A thirteenth aspect relates to the dual-wall airfoil of any preceding aspect, wherein an outer surface of the spar is a continuous, unbroken surface between the first inlet and the second inlet. A fourteenth aspect relates to a method of cooling an airfoil, the method comprising: supplying a cooling fluid to a first internal cavity of an airfoil spar and a second internal cavity of the airfoil spar; directing the cooling fluid from the first internal cavity through a first inlet to a dual feed circuit, the first inlet adjacent to a first dam of the dual feed circuit; directing the cooling fluid from the second internal cavity though a second inlet to the dual feed circuit, the second inlet adjacent to a second dam of the dual feed circuit; directing the cooling fluid from the first inlet downstream through a plurality of diamond pedestals and through a circuit outlet; directing the cooling fluid from the second inlet upstream through the plurality of diamond pedestals and through the circuit outlet; and directing the cooling fluid from the circuit outlet along an outer surface of the airfoil downstream of the circuit outlet. A fifteenth aspect relates to method of aspect14, wherein the first internal cavity is disposed at a leading edge of the airfoil. A sixteenth aspect relates to the method of any preceding aspect, wherein the second internal cavity is disposed at a trailing edge of the airfoil. A seventeenth aspect relates to the method of any preceding aspect, wherein the first inlet comprises a single row of holes connecting the first internal cavity to the dual feed circuit. An eighteenth aspect relates to the method of any preceding aspect, wherein the second inlet comprises a single row of holes connecting the second internal cavity to the dual feed circuit. In addition to the features mentioned in each of the independent aspects enumerated above, some examples may show, alone or in combination, the optional features mentioned in the dependent aspects and/or as disclosed in the description above and shown in the figures. | 33,169 |
11859512 | It is noted that the drawings of the disclosure are not necessarily to scale. The drawings are intended to depict only typical aspects of the disclosure and therefore should not be considered as limiting the scope of the disclosure. In the drawings, like numbering represents like elements between the drawings. DETAILED DESCRIPTION As an initial matter, in order to clearly describe the subject matter of the current disclosure, it will become necessary to select certain terminology when referring to and describing relevant machine components within an illustrative industrial machine in the form of a turbomachine. To the extent possible, common industry terminology will be used and employed in a manner consistent with its accepted meaning. Unless otherwise stated, such terminology should be given a broad interpretation consistent with the context of the present application and the scope of the appended claims. Those of ordinary skill in the art will appreciate that often a particular component may be referred to using several different or overlapping terms. What may be described herein as being a single part may include and be referenced in another context as consisting of multiple components. Alternatively, what may be described herein as including multiple components may be referred to elsewhere as a single part. In addition, several descriptive terms may be used regularly herein, and it should prove helpful to define these terms at the onset of this section. These terms and their definitions, unless stated otherwise, are as follows. As used herein, “downstream” and “upstream” are terms that indicate a direction relative to the flow of a fluid, such as the working fluid through the turbine engine or, for example, the flow of air through the combustor or coolant through one of the turbine's component systems. The term “downstream” corresponds to the direction of flow of the fluid, and the term “upstream” refers to the direction opposite to the flow (i.e., the direction from which the flow originates). It is often required to describe parts that are disposed at differing radial positions with regard to a center axis. The term “radial” refers to movement or position perpendicular to an axis. For example, if a first component resides closer to the axis than a second component, it will be stated herein that the first component is “radially inward” or “inboard” of the second component. If, on the other hand, the first component resides further from the axis than the second component, it may be stated herein that the first component is “radially outward” or “outboard” of the second component. The term “axial” refers to movement or position parallel to an axis. Finally, the term “circumferential” refers to movement or position around an axis. It will be appreciated that such terms may be applied in relation to the center axis of the turbine. In addition, several descriptive terms may be used regularly herein, as described below. The terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur or that the subsequently described component or element may or may not be present, and that the description includes instances where the event occurs or the component is present and instances where it does not or is not present. Where an element or layer is referred to as being “on,” “engaged to,” “connected to” or “coupled to” another element or layer, it may be directly on, engaged to, connected to, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. As indicated above, the disclosure provides a turbine system component. The turbine system component includes a body having an exterior surface, and a cooling passage defined in the body. The cooling passage may be a cooling passage as well as other flow metering passages, orifices or other similar elements of a gas turbine component that, when this process is applied, reduces the flow through that portion of the system. The cooling passage extends to an exterior surface of the body and has a first cross-sectional area. The turbine system component also includes a hollow member coupled in the cooling passage and defining a first exit opening at the exterior surface of the body. The first exit opening in the hollow member has a second cross-sectional area that is less than the first cross-sectional area, creating an exit opening with a smaller dimension than the original cooling passage. Coupling of the hollow member in one or more cooling passages according to embodiments of a method of the disclosure allows reduction in the cross-sectional area of the cooling passage at the exterior surface of the body, and reduces the cooling capabilities of the cooling passage. A cooling profile of the turbine system component can be generated to identify those cooling passages having excess cooling so they can have their exit openings reduced in cross-sectional area, allowing the saved cooling potential to be used more efficiently elsewhere in the turbine or turbine system component. FIG.1shows a schematic view of an illustrative industrial machine in the form of a turbomachine100. Some of the turbine system components of turbomachine100may include a cooling passage according to teachings of the disclosure. In the example, turbomachine100is in the form of a combustion or gas turbine system. Turbomachine100includes a compressor102and a combustor104. Combustor104includes a combustion region106and a fuel nozzle assembly108. Turbomachine100also includes a turbine assembly110and a common compressor/turbine shaft112(sometimes referred to as a rotor112). In one embodiment, turbomachine100may be a 7HA.04 gas turbine (GT) system, commercially available from General Electric Company, Greenville, S.C. The present disclosure is not limited to any one particular GT system and may be implanted in connection with other engines including, for example, the other HA, F, B, LM, GT, TM and E-class engine models of General Electric Company, and engine models of other companies. The present disclosure is not limited to any particular turbine or turbomachine, and may be applicable to, for example, steam turbines, jet engines, compressors, turbofans, etc. Furthermore, the present disclosure is not limited to any particular component and may be applied to any form of hot component exposed to, for example, hot combustion gases in a combustor or a hot gas path of a turbine, and requiring cooling. The disclosure may also be applied to any industrial machine, other than a turbomachine, that requires cooling reduction of a hot component. Continuing withFIG.1, air flows through compressor102and compressed air is supplied to combustor104. Specifically, the compressed air is supplied to fuel nozzle assembly108that is integral to combustor104. Assembly108is in flow communication with combustion region106. Fuel nozzle assembly108is also in flow communication with a fuel source and channels fuel and air to combustion region106. Combustor104ignites and combusts fuel. Combustor104is in flow communication with turbine assembly110for which gas stream thermal energy is converted to mechanical rotational energy. Turbine assembly110includes a turbine111that rotatably couples to and drives rotor112. Compressor102also is rotatably coupled to rotor112. In the illustrative embodiment, there is a plurality of combustors106and fuel nozzle assemblies108. FIG.2shows a cross-sectional view of a part of an illustrative turbine assenbly110of turbomachine100(FIG.1). Turbine111of turbine assembly110includes a row or stage of nozzles120coupled to a stationary casing122of turbomachine100and axially adjacent a row or stage of rotating blades124. A stationary nozzle126(also known as a vane) may be held in turbine assembly110by a radially outer platform128and a radially inner platform130. Each stage of blades124in turbine assembly110includes rotating blades132coupled to rotor112and rotating with the rotor. Rotating blades132may include a radially inner platform134(at root of blade) coupled to rotor112and a radially outer tip136(at tip of blade). Shrouds138may separate adjacent stages of nozzles126and rotating blades132. A working fluid140, including for example combustion gases in the example gas turbine, passes through turbine111along what is referred to as a hot gas path (hereafter simply “HGP”). The HGP can be any area of turbine111exposed to combustion gases having hot temperatures. Various components of turbine111are exposed directly or indirectly to the HGP in turbine111, or hot combustion gases in combustor104, and may comprise a hot gas turbine system component200(hereinafter “turbine system component”). In the example turbine111, nozzles126, blades132and shrouds138are all examples of turbine system components that may benefit from the teachings of the disclosure. It will be recognized that other parts of turbine111exposed directly or indirectly to the HGP may also be considered turbine system components capable of benefiting from the teachings of the disclosure. FIGS.3-5show perspective views of examples a turbine system component200in which teachings of the disclosure may be employed.FIG.3shows a perspective view of turbine system component200in the form of a rotating blade132. Rotating blade132includes a root142by which rotating blade132attaches to rotor112(FIG.2). Root142may include a dovetail144configured for mounting in a corresponding dovetail slot in the perimeter of a rotor wheel146(FIG.2) of rotor112(FIG.2). Root142may further include a shank148that extends between dovetail142and platform134, which is disposed at the junction of airfoil152and root142and defines a portion of the inboard boundary of HGP through turbine assembly110. It will be appreciated that airfoil152is the active component of rotating blade132that intercepts the flow of working fluid and induces the rotor disc to rotate. It will be seen that airfoil152of rotating blade132includes a concave pressure side (PS) outer wall154and a circumferentially or laterally opposite convex suction side (SS) outer wall156extending axially between opposite leading and trailing edges158,160respectively. Sidewalls154and156also extend in the radial direction from platform150to radial outer tip136. Tip136may include any now known or later developed tip shroud (not shown). A cooling passage202(FIGS.6-16) according to embodiments of the disclosure can be used, for example, within airfoil152, platform134or other parts of rotating blade132. FIG.4shows a perspective view of a turbine system component200in the form of a stationary nozzle126. Nozzle126includes radial outer platform128by which nozzle126attaches indirectly to stationary casing122(FIG.2) of the turbomachine. Outer platform128may include any now known or later developed mounting configuration for mounting in a corresponding mount in the casing. Nozzle126may further include radially inner platform130for positioning between adjacent turbine rotating blades132(FIG.3) platforms134(FIG.3). Platforms128,130define respective portions of the outboard and inboard boundary of the HGP through turbine assembly110. It will be appreciated that airfoil176is the active component of nozzle126that intercepts the flow of working fluid and directs it towards turbine rotating blades132(FIG.3). It will be seen that airfoil176of nozzle126includes a concave pressure side (PS) outer wall178and a circumferentially or laterally opposite convex suction side (SS) outer wall180extending axially between opposite leading and trailing edges182,184, respectively. Sidewalls178and180also extend in the radial direction from platform130to platform128. A cooling passage202(FIGS.6-16) according to embodiments of the disclosure can be used, for example, within airfoil176, platforms128,130or other parts of nozzle126. FIG.5shows a perspective view of turbine system component200in the form of a shroud138. Shroud138may include a platform190for positioning between tips136(FIGS.2-3) of turbine rotating blades132(FIGS.2-3) and radially outer platforms128(FIGS.2and4) of nozzles126(FIGS.2and4). Shroud138may fasten to casing122(FIG.2) in any fashion. A cooling passage202(FIGS.6-16) according to embodiments of the disclosure can be used, for example, within face192or an inner surface194or other parts of shroud138. Referring collectively toFIGS.3-5, as noted, embodiments of the disclosure described herein may be applied to any turbine system component200of turbine111(FIG.2), such as but not limited to turbine rotating blades132(FIG.3), nozzles126(FIG.4) and/or shrouds138(FIG.5). It is emphasized however that teachings of the disclosure are also applicable to combustor104components such as nozzles, liners, flow channels, head end components, among others. It will be recognized that the turbine system components200oftentimes include one or more cooling circuits therein that include one or more cooling passages202to deliver a coolant, typically a gas such as air, to parts thereof exposed to hot combustion gases of combustor104or the HGP of turbine111, to cool those parts. Referring toFIGS.6-16, for purposes of description, cooling passage202according to embodiments of the disclosure will be illustrated and described relative to a schematic body210, which could include any part of turbine system component200such as but not limited to trailing edge160,184of airfoil152,176for rotating blade132or nozzle126, respectively. It is emphasized that the teachings of the disclosure may be applied to any cooling passage202exiting an exterior surface212of a body200in any turbine system component200. FIG.6shows a schematic length-wise, cross-sectional view of a cooling passage202in an illustrative turbine system component200, andFIG.7shows a schematic width-wise, cross-sectional view of a cooling passage202of an illustrative turbine system component200, according to embodiments of the disclosure. Turbine system component200includes body210having exterior surface212. As noted, body210may be part of a hot gas path component of turbine111(FIG.2). Turbine system component200also includes cooling passage202defined in body210. Cooling passage202may be fluidly coupled to any cooling circuit(s) within body210. Body210can be any structure capable of having cooling passage202therein such that it extends to an (original) exit opening214in exterior surface212thereof. Body210can include any now known or later developed material for a hot component. In the setting of turbine111, body210may include a nickel or cobalt-based superalloy. More particularly, it may include a superalloy appropriate for turbine system components such as but not limited to: R108, MarM-247, GTD-111; nickel-based superalloys such as MarM 247/CM-247, GTD-222/241/262/111/141/444, Rene N5/N4/N400/N500, Inco 738; or similarly structured cobalt superalloys. Cooling passage202has a cross-sectional area in body210, referred to herein as a “passage cross-sectional area.” The cross-sectional area of cooling passage202may vary along its length. The passage cross-sectional area can be calculated as an average cross-sectional area over a length of cooling passage202, excluding where a hollow member220as described herein is used. InFIG.7, cooling passage202has a generally circular width-wise cross-section, such that the passage cross-sectional area is circular. However, cooling passage202may have a variety of non-circular cross-sectional shapes. Cooling passage202has a generally linear or straight layout, but may have some curvature. A cooling passage202length may be that part of it that is generally linear and fluidly communicates with exterior surface212of body210. FIGS.6and7also show turbine system component200including a hollow member220coupled in cooling passage202and defining a (new) exit opening222at exterior surface212of body210. Hollow member220, at exit opening222, has a cross-sectional area that is less than the passage cross-sectional area. For reference purposes, the cross-sectional area of hollow member220is referred to herein as the “member cross-sectional area.” In this manner, hollow member220reduces the amount of coolant passing through cooling passage202and out of exit opening222compared to original exit opening214, reducing the cooling capabilities of cooling passage202. The reduction in cross-sectional area of exit opening222can be user defined. In one example, member cross-sectional area is about 30% to 50% of the passage cross sectional area. Alternatively, the passage cross-sectional area is about 2 to 3 times larger than the member cross-sectional area. It will be recognized that the cross-sectional areas may vary depending on a number of factors such as but not limited to, turbine system component200size, location of turbine system component to be cooled, amount of cooling desired, and/or the particular cooling passage. Hollow member220has an exterior cross-section shaped to allow coupling to an interior cross-section of cooling passage202. Hollow member220may be coupled in cooling passage202in body210by any number of joining techniques including brazing, soldering, resistance welding, among other techniques. In one embodiment, shown inFIG.7, hollow member220may be coupled in cooling passage202in body210by a braze material226. In another embodiment, braze material26may have a maximum thickness of 300 μm. Braze material226may include any appropriate material for brazing the materials of body210and hollow member220, such as but not limited to nickel-based, low-melt temperature braze materials such as AMS4782, 103, D15, DF4B or B1P braze materials. Hollow member220is made of a material having a melt temperature higher than an operating temperature of the turbine system. Accordingly, operation of the turbine system does not impact hollow member220, e.g., its internal cross-sectional area does not change. Hollow member220may include, for example, a nickel-chromium-based superalloy, a cobalt-based superalloy, or a stainless steel, such as but not limited to: Inconel® 625 (available from Special Metals Corporation), or 300 series stainless steels. In one embodiment, hollow member220may extend inwardly of exterior surface212at exit opening222no less than a hydraulic diameter of cooling passage202. In certain embodiments, hollow member220may extend inwardly (see distance D) of exterior surface212at exit opening222from a portion of the length of the cooling passage up to a maximum of an entire length of cooling passage202. Hollow member220may have a variety of shapes. InFIG.7, cooling passage202is shown with a generally circular cross-section. Here, hollow member220has an external cross-section having a shape matching the shape of internal cross-section of at least a portion of cooling passage202. In this example, hollow member220may be tubular. Hollow member220may have a minimum wall thickness in a range of, for example, 0.1 to 0.3 millimeters, and the wall thickness is generally consistent along is length. An interior cross-section of cooling passage202may have a number of different shapes that hollow member220can be formed to accommodate.FIG.8shows a schematic width-wise, cross-sectional view of cooling passage202, according to another embodiment of the disclosure. Cooling passage202inFIG.8has a generally circular cross-section but includes a plurality of turbulators228, e.g., protrusions or dimples, on an interior surface thereof. Turbulator228may be provided to, for example, improve cooling capabilities of a coolant flow therethrough. Cross-sectional shapes other than circular are also possible, e.g., oval or otherwise oblong, polygonal, etc. Hollow member220may have an accommodating external cross-section to allow insertion into original exit opening214of, and/or coupling in, cooling passage202at exterior surface212in body210. For example, hollow member220may have a circular cross-section smaller than in a smallest diameter between turbulators228, or it may include seats to capture turbulator228, etc. FIG.9shows a schematic width-wise, cross-sectional view of hollow member220and cooling passage202, according to yet another embodiment of the disclosure. In certain embodiments, hollow member220need not be tubular, e.g., with inner and outer cross-sectional shapes that are circular along its length. That is, the external cross-section of hollow member220may be different than an internal cross-section of hollow member220. Hollow member220may have an external cross-section having a shape matching a shape of an internal cross-section of at least a portion of cooling passage202. InFIG.9, for example, an external cross-section of hollow member202is generally circular to match an internal cross-section of at least a portion of cooling passage202, and the internal cross-section of hollow member220(e.g., polygonal such as square) may be different than the external cross-section of hollow member220(e.g., circular). Other shapes are also possible for both the external and internal cross-sections of hollow member220. FIG.10shows a schematic length-wise, cross-sectional view of hollow member220and cooling passage202, according to another embodiment of the disclosure. In previous embodiments, hollow member220may have the same internal and external shapes along its length having the same dimensions. That is, at any length-wise cross-section, a wall thickness on both sides of hollow member220would have a uniform length-wise thickness. In alternative embodiments, shown inFIG.10, hollow member220may have a cross-sectional area at an inner end230thereof internal to body210that is different than member cross-sectional area at exit opening222. In this case, hollow member220has a larger cross-sectional area where it fluidly meets the passage cross-sectional area of cooling passage202within body210than member cross-sectional area at exit opening222. That is, its wall thickness increases and its cross-sectional are decreases as coolant flow progresses from cooling passage202towards exit opening222. Hence, hollow member220becomes narrower as flow progresses from cooling passage202to exit opening222. Hollow member220can include a variety of other features including but not limited to: flared ends, inner turbulators, etc. Turbine system components200oftentimes include a plurality of cooling passages202, each of which may exit body210at exterior surface212.FIG.11shows an end view of exterior surface212of body210of a turbine system component200including a plurality of cooling passages202(inside body210). In this example, all cooling passages202(inside body210) include hollow member220therein. Hence, all cooling passages202have the smaller, member cross-sectional area in body210. In this manner, the cooling capability of all of cooling passages202have been reduced. In an alternative embodiment, only some of cooling passages202may include hollow members220therein.FIG.12shows an end view of exterior surface212of body210of a turbine system component200including a plurality of cooling passages202A,202B (inside body210), some of which include hollow members220and some of which do not. In this case, hollow member220may be used in only select cooling passages202A of a plurality of cooling passages defined in body210. InFIG.12, hollow member220defines exit opening222at exterior surface212of body210having the member cross-sectional area for each of the selected cooling passages202A of the plurality of cooling passages202A,202B. Thus, each of the selected cooling passages202A of the plurality of cooling passages have the smaller member cross-sectional area in body210at exit opening222thereof in exterior surface212of body210. The other cooling passages202B that do not include hollow member220remain having the larger passage cross-sectional area at original exit opening214. That is, a plurality of other cooling passage(s)202B may be defined in body210, with each of cooling passages202B in body210exiting exterior surface212of body210at exit opening214defined in body210having the larger passage cross-sectional area. Cooling passages202B also have the original, larger cooling capability. In a given turbine system component200, any number of cooling passages202or different sets of cooling passages202can be resized with the same sized hollow member220or different sized hollow members220. Cooling passage(s)202A and cooling passage(s)202B having exit openings222,214, respectively, that have different cross-sectional areas may be arranged in any desired manner. InFIG.12, for example, two cooling passages202B are separated by six cooling passages202A in a pattern that may or may not repeat. In another embodiment, shown inFIG.13, the different cooling passages202A,202B may alternate along exterior surface212of body210. Any pattern may be employed to obtain the desired cooling characteristics. Referring toFIGS.14-16, methods according to various embodiments of the disclosure will be described. Cooling passages202in which a hollow member220is employed can be selected in a number of ways. As noted, in one example, all cooling passages202can receive a respective hollow member220(FIG.11). In another example, cooling passages202to receive a respective hollow member220can be randomly selected. In another example, cooling passages202to receive a respective hollow member220can be selected to form a certain pattern. For example, among many other arrangements, cooling passages202A,202B can be arranged with: alternating cooling passages; one or more cooling passages with hollow members adjacent one or more cooling passage without; repeating patterns; a percentage of cooling passages; and/or on certain locations on turbine system component200. In any event, at least one cooling passage202from the plurality of cooling passages to receive a hollow member220can be identified based on a cooling profile of turbine system component200indicating any cooling passage(s)202having excess cooling capacity. A cooling profile can be ascertained using any now known or later developed software system employing empirical data, measured data and/or thermal modeling. In terms of empirical data, in one non-limiting example, a flow of air may be measured on turbine system components using a flow bench that pressurizes the component and measures the flow of air out of the cooling passages. The cooling profile can be generated based on the cooling attributes, measured flow characteristics, and/or other flow characteristics, and the cooling passage(s)202C can be identified as part of the method described herein. That is, the method may include identifying cooling passage(s)202C from the plurality of cooling passages defined in body210of turbine system component200based on the cooling profile of the turbine system component. Alternatively, the cooling profile and/or identification can be otherwise obtained, e.g., created by a third party and provided for use with the method described herein. In any event, the cooling profile identifies cooling passages202that have excess cooling capacity. “Excess cooling capacity” can be identified, for example, by an excess air flow volume or flow rate compared to a required or desired airflow threshold, or it can be identified by cooling beyond a predetermined cooling threshold, e.g., a desired temperature, collective temperature amongst a number of cooling passages, among other options. The threshold of the desired parameter that indicates excess cooling capacity may be adjusted for any performance reason. It may be advantageous to reduce cooling passage202cross-sectional area of the identified cooling passages to reduce their cooling capability. The saved cooling capability can be used in another location or for a different purpose, increasing the overall efficiency of, for example, turbine system component200and/or turbomachine100(FIG.1). The cooling capabilities of a particular cooling passage202can be based a wide variety of factors such as but not limited to: exit opening cross-sectional area; passage cross-sectional area; passage and exit opening physical condition (e.g., physically closed); clogging; oxidation or other wear to exterior surface212; conditions of upstream cooling passages or circuits; number of cooling passages202; inner and outer diameter of hollow member220therein; and/or coolant temperature, pressure, flow rate. Hollow member220can be selected to obtain the desired cooling capabilities. FIG.14shows an end view of exterior surface212of body210of a turbine system component200including a plurality of cooling passages202(inside body210). Certain cooling passages202C have been identified as locations having excess cooling capability, and thus targeted to receive hollow members220.FIG.15shows coupling a hollow member220into cooling passage(s)202C (six shown) in exterior surface212of body212of turbine system component200. As noted, cooling passage(s)202C defined in body210have passage cross-sectional area. A cleaning of cooling passage(s)202C, e.g., an interior surface thereof, may be optionally performed prior to inserting hollow member(s)210into cooling passage(s)202C. The cleaning may include but is not limited to, a chemical or abrasive/mechanical cleaning capable of ensuring proper coupling of hollow members220with whatever joining technique is employed. As shown inFIG.15, the coupling may include inserting a hollow member220into selected cooling passage(s)202C. Hollow members220may extend inwardly of exterior surface212at exit opening222no less than a hydraulic diameter of cooling passage202. The extent to which hollow member220extends into cooling passage202C can be set, for example, by the length of cooling passage, or the extent to which hollow members220are positioned in cooling passages202C.FIG.15also shows physically coupling hollow member(s)220in respective cooling passage(s)202C, i.e., so they cannot be removed. The physical coupling may include performing a joining process such as a brazing process to hollow member(s)220. The brazing process may include forming braze material226between at least a portion of hollow member(s)220and respective cooling passage(s)202C in body210. For example, braze material may be applied as: liquid braze material at the exit of cooling passage202that is wicked up between turbine system component200and hollow member220, braze foil between hollow member220and turbine system component200, a dry braze powder or a braze paste/slurry positioned between turbine system component200and hollow member220, among other techniques. The brazing process may also include performing a heat treatment process. The brazing process can be customized for the particular brazing material used and/or the materials of body210and hollow member220. The coupling can be carried out using any appropriate joining equipment240. As shown inFIG.15, a portion242of hollow member(s)220extends outwardly beyond exterior surface212of body210. FIG.16shows an end view of turbine system component200and removing portion242(FIG.15) of hollow member(s)220extending beyond exterior surface212of body210, e.g., by cutting or grinding them off. After the removal, hollow member(s)220define exit opening222in fluid communication with cooling passage(s)202C at exterior surface212of body210, as described herein. Hollow member(s)220at exit opening222have the member cross-sectional area that is less than the passage cross-sectional area, reducing the coolant flow through cooling passages202C. Body210may also include cooling passage(s)202B having the larger, original exit opening214in exterior surface212of body210of turbine system component200. That is, cooling passage(s)202B are defined in body210and have the larger, passage cross-sectional area in body210at original exit opening214in exterior surface212of body210. In one example, passage cross-sectional area may be in a range of 1.31 to 1.70 square millimeters (mm2), and member cross-sectional area may be in a range of 0.58 to 0.62 mm2. A noted, other cross-sectional areas are also possible. Embodiments of the disclosure provide a turbine system component and method to allow reduction in the cross-sectional area of the exit opening of cooling passage(s), and selectively reduce the cooling capabilities of the cooling passage(s). The cooling profile of the turbine system component can be used to identify those cooling passages having excess cooling so they can have their exit openings reduced in cross-sectional area, allowing the saved cooling potential to be used more efficiently elsewhere in the turbine or turbine system component. Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged; such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. “Approximately,” as applied to a particular value of a range, applies to both end values and, unless otherwise dependent on the precision of the instrument measuring the value, may indicate +/−10% of the stated value(s). The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The embodiment was chosen and described in order to best explain the principles of the disclosure and the practical application and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated. | 35,944 |
11859513 | DETAILED DESCRIPTION OF AN EMBODIMENT FIGS.1to4show a movable vane1for a moving wheel of an aircraft turbomachine, and more precisely for a moving wheel of a low-pressure turbine of the turbomachine. The movable vane1could be intended to equip a high-pressure turbine of the turbomachine. The vane1comprises an aerodynamic blade2extending along a stacking axis Z. The blade2comprises a leading edge3and a trailing edge4opposite the leading edge3. In addition, the blade2comprises an intrados side face5and an extrados side face6opposite to the intrados side face5, with the intrados and extrados side faces5,6connecting the leading edge3to the trailing edge4. In a plane P perpendicular to the stacking axis Z, the blade2is profiled along a mean line connecting the leading edge3to the trailing edge4, the mean line separating the vane1into an intrados side and an extrados side. The intrados and extrados faces5,6are curved, and respectively concave and convex. In the present application, the terms “intrados” and “extrados” associated with the different elements of the vane1refer to the intrados and extrados sides. The leading edge3is positioned upstream of the trailing edge4, according to the direction of gas flow around the blade2, and generally following the direction of gas flow in the turbine. In this application, the terms “upstream” and “downstream” are defined in relation to the direction of gas flow around the blade2(and more generally in the turbine). The vane1also comprises an outer heel7and an inner root defining the blade2along the stacking axis Z. More precisely, the blade2is delimited by an inner platform of the root and an outer platform8of the heel7. A moving wheel comprises a disc with an annular row of vanes1on its periphery. Specifically, each root comprises a bulb configured to be engaged in a complementary recess in the disc. The wheel (respectively the vane1) is mobile around an axis of rotation Y coaxial with the axis of the turbomachine. As shown by the arrow inFIGS.2and3, the vane1is movable in rotation about the axis Y from the intrados to the extrados, and in other words here in a trigonometric (counterclockwise) direction of rotation. In this application, the terms “inner”, “outer”, “internal” or “external” are defined in relation to the axis of rotation Y of the vane1(and more generally of the moving wheel). The heel7of the vane1also comprises a first lip9protruding outwards from the outer platform8. The first lip9is inclined upstream at an acute angle to the stacking axis Z. The first lip9extends circumferentially along an axis of elongation X. The heel7comprises a row of ribs10a-10cspaced at a distance from each other. The row comprises at least two ribs10a-10c. The row of ribs10a-10cextends along the axis of elongation X. Each rib10a-10c(or leaf) extends along the stacking axis Z from the outer platform8to the first lip9. Each rib10a-10cis arranged upstream of the first lip9according to the direction of gas flow around the blade2so as to generate turbulence upstream of the first lip9. According to the embodiment illustrated in the figures, the heel7of the vane1comprises a first lip9and a second lip11spaced apart from each other, the second lip11being located downstream of the first lip9. The first lip9and the second lip11are hereinafter referred to as the upstream lip9and the downstream lip11respectively. The upstream lip9is inclined upstream at an angle of 30° to the stacking axis Z, the angle being measured in a plane which is both coincident with the rotational axis Y of the vane1and the stacking axis Z of the vane1. The upstream lip9could be inclined upstream at an acute angle of between 25° and 35° to the stacking axis Z. The downstream lip11extends along the stacking axis Z from the outer platform8. The downstream lip11could be inclined upstream at an angle of up to 10° to the stacking axis Z. Tilting the lips9and11upstream increases the aerodynamic turbulence and thus strengthens the curtain formed by this turbulence, which opposes the passage of gases from upstream to downstream, so as to limit the passage of gas between the moving wheel (respectively the movable vane1) and a block of abradable material12. According to the embodiment illustrated in the figures, the outer platform8of the vane1comprises, from upstream to downstream, an upstream spoiler13extending upstream of the upstream lip9, an upstream surface13a, an downstream surface13b, a central plate14extending between the upstream lip9and the downstream lip11, and a downstream spoiler15extending downstream of the downstream lip11. The heel7also comprises two reinforcing tabs16between the upstream lip9and the plate14, these tabs16being located at each end of the upstream lip9. The plate14comprises a rib17centered on the mean line, with the rib17joining the upstream lip9to the downstream lip11. The plate14also comprises two recesses18on either side of the rib17. The upstream and downstream lips9,11are designed to co-operate in a form-fitting manner with an annular block of abradable material12(e.g. a honeycomb structure) attached to an outer casing surrounding the moving wheel to form a labyrinth-type seal. The outer platforms of the movable vanes1of a same wheel are shaped to interlock with each other so as to externally delimit a portion of flowpath in which a gas stream flows. The outer platforms are thus arranged side by side. Each external platform8is delimited laterally by a male flank19able to fit into a female flank20of an adjacent vane and a female flank20able to receive a male flank19of an adjacent vane. The male and female flanks19,20are respectively arranged on the extrados and intrados sides. For example, the row comprises between two and five ribs. According to the embodiment shown in the figures, the row comprises three ribs10a-10c, referred as first rib10a, second rib10band third rib10cfrom the extrados to the intrados respectively. These three ribs10a-10care spaced apart from each other. The ribs10a-10care positioned at a constant pitch from the male flank19(extrados side). The first rib10ais positioned close to the male flank19. The third rib10cis positioned away from the female flank20. The heel7comprises a protrusion21between the third rib10cand the female flank20. The upstream lip9extends circumferentially along an axis of elongation X. Advantageously, at least one of the ribs10a-10cis inclined at an acute angle A to the axis of elongation X. The acute angle A is defined from the axis of elongation X to the corresponding rib10a-10cin a trigonometric (or counterclockwise) direction. The acute angle A is measured in a plane P perpendicular to the stacking axis Z. The acute angle A is greater than or equal to 30° and less than 90°. According to the embodiment illustrated in the figures, especially inFIG.4, each of the three ribs10a-10cis inclined at an angle of 30° (A=30°) with respect to the axis of elongation X.FIG.4is a top view on which the ribs10a-10care sketched in dotted lines. The construction line T shown inFIG.4corresponds to the origin of the upstream lip9. Advantageously, at least one of the ribs10a-10chas a parallelogram-shaped cross-sectional profile in a sectional plane perpendicular to the stacking axis Z and passing through the corresponding rib10a-10c. According to the embodiment shown in the figures, in particular inFIG.4, each of the three ribs10a-10chas a parallelogram-shaped profile. Advantageously, each of the ribs10a-10ccomprises two flat and parallel intrados side walls22, the intrados side walls22being at a distance B from each other. The distance B is between 0.5 and 3 mm. The distance B corresponds to the thickness of the rib. The distance B is measured in a plane P perpendicular to the stacking axis Z. As shown inFIG.4, front wall23, opposite intrados side walls22are extrados side walls22a. According to the embodiment shown in the figures, especially inFIG.4, the distance B is the same for all three ribs10a-10cand is equal to 1 mm. Advantageously, each of the ribs10a-10ccomprises a flat front wall23. The upstream lip9comprises an outer surface24bounded by a straight downstream edge25and a straight side edge26arranged on the extrados side (hereafter referred to as the extrados side edge26). The distance D between the downstream edge25and the front wall23is less than the length E of the extrados side edge26. The distance D and the length E are measured in a plane P perpendicular to the stacking axis Z. According to the embodiment shown in the figures, in particular inFIG.4, the distance D is identical for the three ribs10a-10c. The distance D is equal to 1.5 mm and the length E is equal to 2.5 mm. Each rib10a-10ccomprises, on the extrados side, a connecting fillet27with the upstream lip9and a connecting fillet27with the upstream spoiler13. Each rib10a-10ccomprises a rounding28between the front wall23and the side wall22orientated on the intrados side. Advantageously, the distance C along the axis of elongation X between two consecutive ribs10a-10cis between 2 and 5 mm. The distance C is measured in a plane P perpendicular to the stacking axis Z. According to the embodiment shown in the figures, especially inFIG.4, the distance C is constant and equal to 3 mm. According to the embodiment shown in the figures, the ribs10a-10chave the same dimensional and geometrical characteristics. The dimensional and geometrical characteristics of each of the ribs may be different. The dimensional and geometrical characteristics of the ribs depend, among other things, on the predefined limit to the thermomechanical stress, the predefined limit to the mass of the vane and the integration of the vane. In order to further limit the gas passage between the moving wheel (respectively the movable vane1) and the block of abradable material12, at least one rib can be installed upstream of the downstream lip11. Such a rib extends along the stacking axis Z from the plate14to the downstream lip11. Such a rib is configured to generate turbulence upstream of the downstream lip11. The technical characteristics associated with the ribs10a-10cof the upstream lip9are transposable to the ribs of the downstream lip11. The vane1, for example, is produced using a method comprising, firstly, obtaining a raw foundry vane using a lost-wax casting process and, secondly, various machining operations carried out on the raw vane in order to obtain a vane1with final dimensions as detailed on the definition drawing. | 10,525 |
11859514 | DETAILED DESCRIPTION In all figures identical features are identified with the same reference numbers. FIG.1shows schematically a gas turbine100with a compressor110, a combustion chamber120and a turbine unit130. The compressor110and the turbine unit130each comprise stationary parts and rotary parts (not shown inFIG.1). According to this exemplary embodiment, an electrical generator150for generating electricity is coupled to a rotor140of the gas turbine. During operation the axial compressor110sucks in ambient air L and conveys it as compressed air VL to its outlet and further to the combustion chamber120. Here, the compressed air VL is mixed with fuel F and burned to a hot gas HG. In the turbine unit130the hot gas HG is expanded. After the expansion the gas leaves the turbine unit130as flue gas RG. The expansion of the hot gas HG generates torque on rotor140in the turbine unit130, which then drives the compressor110and the generator150. The rotor140comprises as rotary parts several rotor disks of which inFIG.2only one rotor disk RD is displayed. On the rotor disk RD, a number of rotor blades RB are attached to the rotor disk RD, of which only one is shown again. Each rotor blade RB comprises an airfoil AF and a blade root BR. For attaching the rotor blades RB onto the rotor disk RD, the rotor disk RD comprises at its outer periphery OP a number of attachment slots AS (FIG.3). Herein the blade roots BR of rotor blades RB are firmly engaged. When the rotor arrangement RA is assembled within the rotor140of the gas turbine100, the rotor140and the rotor disk RD is able to rotate around the machine axis MA. FIG.3is a perspective view onto the rotor arrangement RA and especially onto the lateral surface LS of the rotor disk RD, before assembly of a locking sheet metal strip LSMS. The rotor disk RD comprises at its lateral surface LS an annular groove AG having an annular opening directed in radially outwardly. The lateral surface LS could be either the lateral surface of the upstream side or the downstream side of the rotor disc RD, wherein upstream and downstream are to be determined in reference to the flow direction of the working medium of the compressor or turbine. Radially outwardly relative to the annular groove AG and with rather small distance thereto a number of attachment slots AS are arranged at the outer periphery of the rotor disk RD. InFIG.3only one of the attachment slots is shown. In the attachment slot AS the blade root BR of the rotor blade RB is arranged. Both the attachment slot AS and the blade root BR are shaped complementarily, such that during operation and rotation of the rotor arrangement RA the rotor blades RB are securely attached to the rotor disk RD. According to this exemplary embodiment of the invention, the attachment slot AS and the blade root BR are of fir-tree shape. A front side of the blade root BR is flush with the lateral surface of the rotor disk RD. From said front side a root extension RE protrudes. The root extension RE comprises a root groove RG having an opening towards the machine axis MA. Hence, the root extension RE is embodied as a hook projecting inwardly in such a way, that the opening of the root groove RG and the opening of the annular groove AG are opposingly arranged with flush walls (FIG.6). In the final rotor arrangement RA (FIGS.5and6) the locking sheet metal strip LSMS engages simultaneously the root groove RG and the annular groove AG. The locking sheet metal strip LSMS according to the first exemplary embodiment of the invention comprises, as shown in detail inFIG.6, a C-shaped outer end OE and a C-shaped inner end IE as well as two lateral tongues BT, all extending from a main body MB of the locking sheet metal strip LSMS in all four directions. The tongues are, for example, rectangularly shaped. One of the lateral tongues BT, inFIG.3identified by index1, extends in the same plane as the main body MB of the locking sheet metal strip LSMS, whereas the other lateral tongue BT, inFIG.3identified by index2, is bent. In this regard bent means that the respective tongue extends perpendicular to the plane of the main body MB of the locking sheet metal strip LSMS. During its assembly, the locking sheet metal strip LSMS is moved as shown by arrow AR along the annular groove AG until the lateral tongue BT2contacts root extension RE. The final position of the locking sheet metal strip is shown inFIG.4as plain view onto the rotor arrangement RA. If needed, the locking sheet metal strip LSMS can be fixed temporarily in this position for securing its position during the following bending of the lateral tongue BT1around the bending axis BA. At the beginning of the bending process the required bending force is directed in the axial direction. With continued bending the bending force turns more and more into the tangential direction. The bending of the lateral tongue BT1around the bending axis BA is completed when it contacts the root extension RE in a planar manner, as shown inFIG.5, or with a small gap therebetween. Because of the constant, rather small sheet thickness of the locking sheet metal strip LSMS, a rather small bending force is needed to bring the lateral tongue BT1in its final position. In this position, the locking sheet metal strip LSMS is securely attached to the rotor disk and to the blade root. On other words, the locking sheet metal strip LSMS embraces and/or clamps the root extension RE in a manner which blocks its movement along the annular groove AG in tangential direction. As can be seen inFIG.6the axial width AGW of the annular groove AG, the axial width RGW of the rotor groove RG and the corresponding widths AW of the C-shaped outer end OE and the C-shaped inner end IE of the locking sheet metal strip LSMS are shown. The sizes of all axis widths AGW, RGW, AW are identical to ensure ease of manufacture and assembly and an accurate, clearance-free fit. With that, any axial movement of the respective rotor blade RB, in detail the blade root BR, along the attachment slot AS is avoided, which provides accurate axial positioning of the rotor blade leading to predefined radial gaps between the tip of its airfoil and the opposingly arranged flow path boundary of the compressor resp. turbine. Instead of having C-shaped inner ends and C-shaped outer ends and still for achieving the required axial width AG, a thickening element TE can be firmly attached, e.g., by welding, brazing or the like, onto the locking sheet metal strip LSMS, as shown inFIG.7as a second exemplary embodiment of the invention. This enables easier manufacture, when, because of rather small size of the locking sheet metal strip, the bending of the outer and inner ends is difficult. According to this exemplary embodiment, the tongues that are bent around the bending axis BX, are of triangular shape. In summary the invention relates to a rotor arrangement RA comprising a rotor arrangement RA for a rotor140of a gas turbine100, comprising—at least one rotor disk RD comprising attachment slots for carrying rotor blades RB and an annular groove AG having an annular opening towards the outward direction and—rotor blades RB having an airfoil AF and a blade root BR and assembled in an attachment slot AS, wherein each of the assembled blade roots BR comprises a root extension RE with a root groove RG, said root groove RG facing the annular groove AG when the rotor blade RB is assembled in the attachment slot AS, and wherein for each assembled rotor blade RB a locking element is provided, which locking element engaging, the annular groove AG of the rotor disk RD and the root groove RG of the respective rotor blade RB. For the provision of a light and an easy mountable locking element preferably all locking elements are embodied as a locking sheet metal strip LSMS, which comprises two bended tongues BT embracing the respective root extension RE. | 7,918 |
11859515 | Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present disclosure. Also, common, but well-understood elements that are useful or necessary in a commercially feasible embodiment, are often not depicted to facilitate a less obstructed view of these various embodiments of the present disclosure. Certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. DETAILED DESCRIPTION The following embodiments illustrate flow path designs that shorten an aircraft engine (e.g., its core) length and/or reduce aircraft engine noise, as well as provide other benefits. More specifically, embedding supports struts with inlet stator vanes and/or outlet stator vanes shortens the overall length of the aircraft engine. One or more benefits of shortening the aircraft engine is a reduction of engine weight and improved fuel efficiency. Further, increasing a distance between stator vanes and adjacent rotors without increasing an overall length of the aircraft engine mitigates noise, aeromechanical forcing, and stress. For instance, the designs ofFIGS.3-7are illustrative examples of embodiments that either reduce noise of an engine due to increased spacing between stator vanes and rotors and/or shorten the length of the aircraft engine due to embedding struts with stator vanes. Further, another advantage of the following designs is the ability to achieve one or more of these benefits using the same length of current aircraft engines so to retrofit current aircraft engines and aircraft components. Other benefits might include better turbomachinery efficiencies due to lower stress and forcing sources and turbomachinery component efficiencies due to lower aero loading in vanes. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein. The word “or” when used herein shall be interpreted as having a disjunctive construction rather than a conjunctive construction unless otherwise specifically indicated. The terms “coupled,” “fixed,” “attached to,” and the like refer to both direct coupling, fixing, or attaching, as well as indirect coupling, fixing, or attaching through one or more intermediate components or features, unless otherwise specified herein. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms such as “about”, “approximately”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. For example, the approximating language may refer to being within a 10 percent margin. The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. The foregoing and other benefits may become clearer upon making a thorough review and study of the following detailed description. Referring now to the drawings, and in particular toFIG.1, there is illustrated an exemplary gas turbine engine100. The gas turbine engine100defines an axial direction102, a radial direction104, and a circumferential direction106(i.e., a direction extending about the axial direction A). The gas turbine engine100includes an outer casing112about a fan section108followed by a core section110. The core section110includes an inner casing105that may be substantially tubular and that defines an annular inlet114. The inner casing105encases, in the axial direction102, a compressor section including a low-pressure compressor (LPC)116and a high-pressure compressor (HPC)118, a combustion section120, a turbine section including a high-pressure turbine (HPT)122and a low-pressure turbine (LPT)124, and a jet exhaust nozzle section126. A low pressure (LP) shaft128drivingly connects the LPC116to the LPT124. A high pressure (HP) shaft130drivingly connects the HPC118to the122HPT. The fan section108includes a fan132having a plurality of fan blades134extend in the radial direction104from a disc136. The LPT124drives rotation of the fan132. More specifically, the fan blades134, the disc136, and an actuation member138are rotatable together in the circumferential direction106by LP shaft128in a “direct drive” configuration. Accordingly, the LPT124rotates the fan132at the same rotational speed of the LPT124. A rotatable front hub140covers the disc136and is aerodynamically contoured to promote an airflow through the plurality of fan blades134. Additionally, the fan section108includes an outer nacelle142that circumferentially surrounds the fan section108and a portion of the core section110. More specifically, the nacelle142includes an inner wall144with a section that extends over the core section110to define a bypass airflow passage146therebetween. Additionally, the nacelle142is supported relative to the core section110by a plurality of circumferentially spaced struts148that extend in the radial direction104and are shaped as guide vanes. During operation of the gas turbine engine100, a volume of air150enters the gas turbine engine100through an associated inlet152of the nacelle142. As the volume of air150passes the fan blades134, a first portion of the air154flows into the bypass airflow passage146, and a second portion of the air156flows into the LPC116. The pressure of the second portion of air156is then increased as it flows through the HPC118and into the combustion section120, where it is mixed with fuel and burned to provide combustion gases161. The combustion gases161flow through the HPT122where a portion of thermal and/or kinetic energy from the combustion gases161is extracted via sequential stages of HPT stator vanes that are coupled to an inner casing105and HPT rotor blades that are coupled to the HP shaft130, thus causing the HP shaft130to rotate, which causes operation of the HPC118. The combustion gases161then flow through the LPT124where a second portion of thermal and kinetic energy is extracted from the combustion gases161via sequential stages of LPT stator vanes that are coupled to the inner casing105and LPT rotor blades that are coupled to the LP shaft128, thus causing the LP shaft128to rotate, which causes operation of the LPC and/or the fan132. The combustion gases161subsequently flow through the jet exhaust nozzle section126to provide propulsive thrust. Simultaneously, the pressure of the first portion of air154is substantially increased as the first portion of air154flows through the bypass airflow passage146before it is exhausted from a fan nozzle exhaust section158, also providing propulsive thrust. The HPT122, the LPT124, and the jet exhaust nozzle section126at least partially define a hot gas path for routing the combustion gases161through core section110. It should be appreciated, however, that the exemplary gas turbine engine100depicted inFIG.1and described above is by way of example only, and that in other exemplary embodiments, the gas turbine engine100may have any other suitable configuration. For example, in other exemplary embodiments, the engine100may include any other suitable number of compressors, turbines and/or shaft. Additionally, the gas turbine engine100may not include each of the features described herein, or alternatively, may include one or more features not described herein. Additionally, although described as a “turbofan” gas turbine engine, in other embodiments the gas turbine engine may instead be configured as any other suitable ducted gas turbine engine. FIG.2is a schematic view of a portion of the gas turbine engine100showing a portion of the flow path for the core section110. The flow path is bounded by the inner casing105, a forward end160of the LP shaft128, and the HP shaft130. The flow path guides flow from the LPC116to the HPC118. The struts148support the core section110along the flow path. The LPC116includes a plurality of annular arrays of stator vanes and a plurality of annular arrays of rotor blades. The arrays of LPC stator vanes and LPC rotor blades alternate through the LPC116, as explained further below. The LPC stator vanes extend from the inner casing105that is static, and the LPC rotor blades extend from the forward end160that rotates with the LP shaft128. Similarly, the HPC118includes a plurality of annular arrays of stator vanes and a plurality of annular arrays of rotor blades. The arrays of HPC stator vanes and HPC rotor blades alternate through the HPC118, as explained further below. The HPC stator vanes extend from the static inner casing105, and the HPC rotor blades extend from the HP shaft130. At the downstream end of the LPC116, there is the last array of LPC stator vanes, which may be referred to as the LPC outlet vanes (LPC-OV162). Positioned at the upstream end of the HPC118is the first annular array of HP stator vanes, which may be referred to as the HPC inlet vanes (HPC-IV164). The following describes different configurations of the components of the LPC and the HPC, including the LPC-OV and the HPC-IV. The reference numbers used above will be used in describing the different configurations. Referring toFIG.3andFIGS.9A-9C, there is illustrated an alternate annular compression flow path166. The alternate annular compression flow path166includes arrays of LP rotor blades168alternating with arrays of LP stator vanes170. The most downstream array of LP rotator blades168/172is followed by the LPC-OV170/162. Each of the LPC-OV162includes a trailing edge174. Each strut148includes a leading edge176. The leading edge176may be positioned upstream from the trailing edges174of the LPC-OV162. Embedding the strut148with the LPC-OV162reduces the length of an engine. More specifically, the strut leading edge176of each strut148may be disposed between a leading edge178and the trailing edge174of each of the LPC-OV162, as shown inFIG.9A(see reference line180). Alternatively, the leading edge176of each strut148is substantially aligned with the leading edge178of each of the LPC-OV162, as shown inFIG.9B(see reference line182). In another alternative, the strut leading edge176of each strut148is positioned upstream from the leading edge178of each of the LPC-OV162, as shown inFIG.9C(see reference line184). In some embodiments, the arrays of LPC stator vanes170includes a second to last array of LPC stator vanes186immediately upstream of the furthest downstream array of LPC rotor blades168/172. The second to last array of LPC stator vanes186may have guide vanes, and each guide vane may have a guide vane trailing edge187. In some embodiments, a first axial spacing188between the LPC-OV162and furthest downstream array of LPC rotor blades172is greater than a second axial spacing190between the second to last array of LPC stator vanes186and the furthest downstream array of LPC rotor blades172. In some embodiments, the first axial spacing188is substantially equal to the second axial spacing190. This spacing mitigates engine noise, aeromechanical forcing, and stress. InFIG.4, there is illustrated an alternate flow path191. The alternate flow path191includes arrays of HPC rotor blades192alternating with arrays of HPC stator vanes194. The arrays of HPC rotor blades192include a first array196(most upstream). The arrays of HPC stator vanes194include a first array (most upstream) (HPC-IV164). The HPC-IV164is positioned upstream from the first array of HPC rotor blades196. The arrays of HPC stator vanes194also includes a second most upstream array of HPC stator vanes198. The second most upstream array of HPC stator vanes198is positioned downstream from the first array of HPC rotor blades196. In some embodiments, a strut trailing edge200of each strut148is positioned downstream from a leading edge202of the HPC-IV164, as shown inFIGS.4and9A-9C. More specifically, the strut trailing edge200of each strut148may be positioned between the leading edge202and a trailing edge204of the HPC-IV164, as shown inFIG.9A(see reference line206). Alternatively, the strut trailing edge200of each strut148may be substantially aligned with the trailing edge204of the HPC-IV164, as shown inFIG.9B(see reference line208). In another alternative, the strut trailing edge200of each strut148may be downstream of the trailing edge204HPC-IV164, as shown inFIG.9C(see reference line210). The orientation of the stator vanes is not limited to the orientations shown inFIGS.9A-9C. For instance, the orientation of the IV may be different than that shown, the orientation of the OV may be different than that shown, and the orientation of both the IV and OV may be different than that shown. Embedding the strut148with the HPC-IV164reduces the length of an engine. In some embodiments, a third axial spacing212between the HPC-IV164and the first array of HP compressor rotor blades196is greater than a fourth axial spacing214between the second array of HPC stator vanes198and the first array of HPC rotor blades196. In some embodiments, an increase in axial spacings as described in the present disclosure can mitigate noise reduction, aeromechanical forcing, and stress. In some embodiments, the third axial spacing212is substantially equal to the fourth axial spacing214. Referring toFIG.5, there is shown another alternate flow path218combining the placement of the LPC-OV162and HPC-IV164, as shown, for example, inFIGS.9A and9C. That is, the strut trailing edge200of each strut148is positioned downstream from the leading edge202of the HPC-IV164. Additionally, a strut leading edge176of each strut148is positioned upstream from the trailing edge174of the LPC-OV162. Embedding the strut148with the LPC-OV162and/or the HPC-IV164reduces the length of an engine. With this embodiment, the first axial spacing188and the second axial spacing190may be at least substantially equal. Also, the third axial spacing212and the fourth axial spacing214may be at least substantially equal. Increasing this axial spacing mitigates engine noise, aeromechanical forcing, and stress. As seen inFIG.6, there is shown another alternate flow path220with the strut leading edge176of each strut148is positioned downstream from the LPC-OV162. The HPC-IV164is positioned upstream from the first array of HPC rotor blades192. The strut trailing edge200of each strut148may be positioned relative to the leading edge202and the trailing edge204of each of the HPC-IV164, as shown in any one ofFIGS.9A-9C. Embedding the strut148with the HPC-OV164reduces the length of an engine. In some embodiments, the axial spacing between (1) the strut leading edge176and LPC-OV162, (2) the LPC-OV162and the most downstream array of LPC rotor blades172, and (3) the second to last array of LPC stator vanes186and the most downstream array of LPC rotor blades172are all at least substantially equal. In yet some embodiments, the axial spacing between (1) the HPC-IV164and the first array of HPC rotor blades192and (2) the second array of HPC stator vanes198and the first array of HPC rotor blades192are both at least substantially equal. Increasing this axial spacing mitigates engine noise, aeromechanical forcing, and stress. With reference toFIG.7, there is illustrated another alternate flow path222with the strut leading edge176of each strut148positioned upstream from the trailing edge174of the LPC-OV162. Further, the strut trailing edge200of each strut148is positioned upstream from the HPC-IV164. Embedding the strut148with the LPC-OV162reduces the length of an engine. In some embodiments, the axial spacing between (1) the LPC-OV162and the most downstream array of LPC rotor blades172and (2) the second most array of LPC stator vanes186and the most downstream array of LPC rotor blades172are both at least substantially equal. In some embodiments, the axial spacing between (1) the strut trailing edge200of each strut148and the HPC-IV164, (2) the HPC-IV164and the first downstream array of HPC rotor blades192, and (3) the first downstream array of HPC rotor blades192and second downstream array of HPC stator vanes198are at least substantially equal. Increasing this axial spacing mitigates engine noise, aeromechanical forcing, and stress. FIGS.8A and8Bare views shown in the axial direction. The locations inFIG.2of these views are only indicated to be a general location. More specifically,FIG.8Ais a downstream view of a portion of an exemplary annular compressor flow path224showing the struts148and the LPC-OV162. The LPC-OV162includes an inner flow path surface228on the forward end160of the LP shaft128and an outer flow path surface230on the inner casing105, which also support the LPC-OV162. FIG.8Bis an upstream view of a portion of the annular compressor flow path224showing the struts148and the HPC-IV164. In some embodiments, the HPC-IV164includes an inner flow path surface on the HP shaft130and an outer flow path surface230on the inner casing105, which also supports the HPC-IV164. In some embodiments, a thickness of the strut148is greater than that of the LPC-OV and/or HPC-IV. It is understood that the figures described herein are illustrative non-limiting examples and that the shapes and/or number of struts, stator vanes, and/or rotor blades are not limited to the shapes and/or number of struts, stator vanes, and/or rotor blades shown. Additionally, the chord length of the LPC-OV and HPC-IV shown inFIGS.9A-9Care the same. However, the chord length may vary between each vane of the LPC-OV and/or each vane of the HPC-IV and/or can vary between the LPC-OV and the HPC-IV. FIG.10Aillustrates an exemplary guide vane236that may represent one or both the LPC-OV and HPC-IV. The guide vane236includes a top surface238and a bottom surface240joined at a leading edge242and a trailing edge244. A chord line246extends between the leading edge242and the trailing edge244. FIG.10Billustrates a stacking axis of the guide vane236ofFIG.10A. As shown inFIG.10B, the top and bottom surfaces238,240extend radially outward from an inner base247to an outer end (not shown). The cross-section shown inFIG.10Ais normal to top and bottom surfaces238,240. A mid-line248is shown extending from the leading edge242to the trailing edge244that divides the guide vane236in half. A stacking point250is defined substantially halfway between the leading edge242and the trailing edge244along the mid-line248. A stacking axis252extends along a line formed through the stacking points250along a length of the guide vane236from the inner base247at the inner casing105to the outer end of the guide vane236. As illustrated inFIGS.10A-B, the guide vane236has an airfoil cross-sectional shape. This shape may be applied to all the vanes and blades. While the guide vane236shown inFIG.10Bis linear (i.e., has a constant chord length along its length), the guide vane236also may have a chord length that varies in some regard along its length. In some embodiments, the guide vane236leading edge and trailing edge metal angle varies in radial direction. In yet some embodiments, the guide vane236may have a radial stacking that is not linear in the axial and circumferential directions (e.g., bow, lean, sweep, and/or dihedral stacking). In some embodiments, each or at least one of the LPC-OV and/or each or at least one of HPC-IV is independently and/or as a group movable, variable, and/or rotatable to change corresponding vane angle. In some embodiments, each LPC-OV and/or HPC-IV is fixed against adjustment. With reference toFIGS.9A-9C, the struts148may be asymmetrical along a longitudinal central axis that is parallel to the leading edge176and the trailing edge200to reduce separation of flow moving across them. The improvement derives from a better alignment of surfaces of the struts148with angles and surfaces of adjacent stator vanes (e.g., stator vanes162) than if the struts were symmetrical. More specifically, the surfaces of the struts148adjacent the176leading edge and the trailing edge200can be aligned better with the flow direction when the struts148are asymmetrical. FIG.11illustrates an exemplary strut254that includes a main strut portion256interconnecting a leading edge portion258and a trailing edge portion260. In some embodiments, one or both of the leading edge portion258and the trailing edge portion260may be variably and/or controllably movable (e.g., as indicated by reference number262). This enables better alignment of surfaces of the strut254with angles and surfaces of adjacent stator vanes (e.g., stator vanes162) to reduce separation of flow across it, as with the asymmetrical strut discussed above. Alternatively, in some embodiments, both the leading edge portion258and the trailing edge portion260are fixed relative to the main strut portion256. Also, the leading edge portion258and/or the trailing edge portion260that are movable may be used with the LPC-OV162and/or HPC-IV164. Referring toFIG.12, there is an exemplary method264of assembling a portion of gas turbine engine in accordance with some embodiments. For example, the method264and/or one or more of the steps of the method264are applicable to one or more of the foregoing designs. The method264includes a step of providing an outer engine casing266, a low-pressure shaft, and a high-pressure shaft that combine to define an annular flow path. The method further includes the step of coupling a plurality of circumferentially spaced struts to the outer casing to support the outer casing268. In addition, the method includes the step270of coupling a plurality of circumferentially spaced low-pressure compressor rotor blades to the low-pressure shaft be rotated by the low-pressure shaft and the step of coupling a plurality of circumferentially spaced low-pressure stator vanes to the outer casing272. The method further includes the step of positioning a row of outlet guide vanes at the end of the low-pressure compressor section and downstream from a last array of low-pressure rotor blades274. Moreover, the method includes a step of positioning a strut leading edge of each strut upstream from the trailing edges of the outlet guide vanes276. In some configurations, the method264may include the step of coupling a plurality of circumferentially spaced high-pressure compressor stator vanes within the flow path. The high-pressure compressor stator vanes may include a first high-pressure compressor stator stage (an array of inlet guide vanes). The method264may include positioning a strut trailing edge of each strut downstream from leading edges of the inlet guide vanes. Further, the method264may include coupling a plurality of circumferentially spaced high-pressure compressor stator vanes within the compressor flow path. In some embodiments, the plurality of circumferentially spaced high-pressure compressor stator vanes may be coupled to include a first high-pressure compressor stator and a second high-pressure compressor stator stage. The first high-pressure stator stage may be an annular array of inlet guide vanes. The second high-pressure compressor stator stage may include an annular array of stator vanes. In some embodiments, the method264may include positioning a strut trailing edge of each strut upstream from the inlet guide vanes and positioning the inlet guide vanes upstream from the first array of high-pressure compressor rotor blades. The method264may include positioning the first array of high-pressure rotor blades upstream from the second row of high-pressure compressor stator vanes. Each corresponding axial spacing (1) between the strut trailing edge of each strut and the row of inlet guide vanes IVs, (2) between the row of inlet guide vanes and the first array of high-pressure compressor rotor blades, and (3) between the first array of high-pressure compressor rotor blades and the row of high-pressure compressor stator vanes may be at least substantially equal. Although the foregoing designs include only a single LPC stator stage and/or a single HPC stator stage, those skilled in the art would understand from this disclosure that two or more LPC stator stages and/or two or more HPC stator stages can also be positioned similarly. Furthermore, the present disclosure may be applicable to various configurations when upstream stator vanes (e.g., LP-OV), struts, and/or downstream stator vanes (e.g., HP-IV) are involved regardless of the other upstream and/or downstream components. In a non-limiting example, the upstream component may be a fan and the downstream component may be a low-pressure compressor. In such an example, the present disclosure may be applicable to a fan, LPC-OV, strut, and low-pressure compressor inlet guide vanes configuration. In another example, there may be no upstream component involved. In such an example, the present disclosure may be applicable to the strut and the downstream compressor inlet guide vanes configuration. In another example, there may be upstream stator vanes and no upstream compression component. In such an example, the present disclosure may be applicable to the upstream stator vanes, strut, and the downstream compressor inlet guide vanes configuration. Further, there may be two stator vane arrays back-to-back (i.e., without at any intervening other components, such as rotor components). For example, with reference toFIG.3, the LPC-OV162and the LPC stator vanes170immediately upstream from it may not be separated by the rotor blade array172. In another example, with reference toFIG.4, HPC-IV164and the stator vane array194immediately downstream from it may not be separated by the rotor blade array196. Further aspects of the present disclosure are provided by the subject matter of the following clauses. There is provided a gas turbine engine having a casing defining at least a portion of a flow path; at least one stator vane array disposed within the flow path, the at least one stator vane array having outlet vanes, and the outlet vanes each having an outlet vane trailing edge; and at least one strut having a strut leading edge, the strut leading edge being upstream from the outlet vane trailing edges. The gas turbine engine of the preceding clause may further include the at least one stator vane array having a first stator vane array downstream of a second stator vane array, the first stator vane array having the outlet vanes, the second stator vane array having guide vanes, the guide vanes each having a guide vane trailing edge, and the strut leading edge being upstream of each guide vane trailing edge. The gas turbine engine of one or more of the preceding clauses may further include at least one rotor blade array disposed within the flow path; the at least one stator vane array having a first stator vane array downstream from a second stator vane array, the first stator vane array having the outlet vanes; the outlet vanes being downstream from the at least one rotor blade array and the second stator vane array; and the at least one rotor blade array being upstream of the strut leading edge. The gas turbine engine of one or more of the preceding clauses may further include the outlet vanes each having an outlet vane leading edge, and the strut leading edges being upstream of each outlet vane leading edge. The gas turbine engine of one or more of the preceding clauses may further include that the at least one stator vane array have a first stator vane array and a second stator vane array, the first stator vane array having the outlet vanes, the second stator vane array having inlet vanes and being downstream of the first stator vane array, the inlet vanes each having an inlet vane leading edge, and the strut trailing edge being downstream from each inlet vane leading edge. The gas turbine engine of one or more of the preceding clauses may also include that the inlet vanes each have an inlet vane trailing edge, and the strut trailing edges being downstream from each inlet vane trailing edge. The gas turbine engine of one or more of the preceding clauses also may include that the at least one strut has a main portion between a leading edge portion and a trailing edge portion, and at least one of the leading edge portion and the trailing edge portion being movable. The gas turbine engine of one or more of the preceding clauses may further include at least one rotor blade array and wherein the at least one stator vane array comprises a first stator vane array downstream of a second stator vane array, the at least one rotor blade array being between the first stator vane array and the second stator vane array, a first axial spacing between the first stator vane array and the at least one rotor blade array being greater than a second axial spacing between the second stator vane array and the at least one rotor blade array. The gas turbine engine of one or more of the preceding clauses also may have at least one rotor blade array and wherein the at least one stator vane array comprises a first stator vane array downstream of a second stator vane array, the at least one rotor blade array being between the first stator vane array and the second stator vane array, a first axial spacing between the first stator vane array and the at least one rotor blade array is at least substantially equal to a second axial spacing between the second stator vane array and the at least one rotor blade array. The gas turbine engine of one or more of the preceding clauses may further include that the at least one stator vane array comprises a first stator vane array, a second stator vane array, and a third stator vane array, the first stator vane array having the outlet vanes, the second stator vane array being downstream of the first stator vane array, the third stator vane array being downstream of the second stator vane array, at least one rotor blade array being between the second stator vane array and the third stator vane array, axial distances between the at least one strut and the second stator vane array, the at least one rotor blade array and the second stator vane array, and the at least one rotor blade array and the third stator vane array being at least substantially equal. There is further provided a gas turbine engine comprising: an outer casing defining at least in part a flow path; at least one stator vane array within the flow path, the at least one stator vane array including inlet vanes, and the inlet vanes each having an inlet vane leading edge; and at least one strut having a strut trailing edge downstream from each inlet vane leading edge. The gas turbine engine of one or more of the preceding clauses may further include at least one rotor blade array in the flow path, and the inlet vanes being upstream of the at least one rotor blade array. The gas turbine engine of one or more of the preceding clauses may also include that the inlet vanes each includes an inlet vane trailing edge, and the strut trailing edge being downstream of each inlet vane trailing edges. The gas turbine engine of one or more of the preceding clauses may further include that the at least one stator vane array comprises a first stator vane array and a second stator vane array, the first stator vane array being downstream of the second stator vane array and having the inlet vanes, the second stator vane array having outlet vanes, each outlet vane having an outlet vane trailing edge, and the at least one strut having a strut leading edge upstream of each outlet vane trailing edges. The gas turbine engine of one or more of the preceding clauses may further include that the outlet vanes each comprise an outlet vane leading edge, and the strut leading edge being upstream of each outlet vane leading edge. The gas turbine engine of one or more of the preceding clauses may further have at least one rotor blade array and wherein the at least one stator vane array comprises a first stator vane array and a second stator vane array, the second stator vane array being downstream of the first stator vane array, the at least one rotor blade array being between the first stator vane array and the second stator vane array, a first axial spacing between the first stator vane array and the at least one rotor blade array being greater than a second axial spacing between the at least one rotor blade array and the second stator vane array. The gas turbine engine of one or more of the preceding clauses may further have at least one rotor blade array and wherein the at least one stator vane array comprises a first stator vane array and a second stator vane array, the second stator vane array being downstream of the first stator vane array, the at least one rotor blade array being between the first stator vane array and the second stator vane array, a first axial spacing between the first stator vane array and the at least one rotor blade array being substantially equal to a second axial spacing between the at least one rotor blade array and the second stator vane array. The gas turbine engine of one or more of the preceding clauses also may include that the inlet vanes are variable in stagger angle. There is provided method of assembling a gas turbine engine comprising: combining a casing and a shaft to define at least in part an annular flow path; coupling a first stator vane array to the outer casing in the annular flow path, the first stator vane array having outlet vanes with outlet vane trailing edges; coupling a second stator vane array to the casing in the annular flow path, the second stator vane array having inlet vanes with inlet vane leading edges; and coupling at least one strut to the casing, the at least one strut having a strut leading edge and a strut trailing edge, the strut leading edge being upstream of the each outlet vane trailing edge and/or the strut trailing edge being downstream of each inlet vane trailing edge. There is further provided a gas turbine engine comprising: a casing defining at least a portion of a flow path, a first stator vane array disposed in the flow path and including outlet vanes, the outlet vanes each having an outlet vane trailing edge: a second stator vane array disposed in the flow path and including inlet vanes, and the inlet vanes each having an inlet vane leading edge; and at least one strut having a strut leading edge and a strait trailing edge, the strut leading edge being upstream from each outlet vane trailing edge and/or the strut trailing edge being downstream from each outlet vane leading edge. The gas turbine engine of one or more of the preceding clauses also may include the strut leading edge being upstream from each outlet vane trailing edge and the strut trailing edge being downstream from each outlet vane leading edge. It will be understood that various changes in the details, materials, and arrangements of parts and components which have been herein described and illustrated to explain the nature of the disclosure may be made by those skilled in the art within the principle and scope of the appended claims. Furthermore, while various features have been described with regard to particular embodiments, it will be appreciated that features described for one embodiment also may be incorporated with the other described embodiments. | 36,220 |
11859516 | DETAILED DESCRIPTION Reference will now be made in detail to present embodiments of the disclosure, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the disclosure. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations. Additionally, unless specifically identified otherwise, all embodiments described herein should be considered exemplary. As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “forward” and “aft” refer to relative positions within a gas turbine engine or vehicle, and refer to the normal operational attitude of the gas turbine engine or vehicle. For example, with regard to a gas turbine engine, forward refers to a position closer to an engine inlet and aft refers to a position closer to an engine nozzle or exhaust. The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. The terms “coupled,” “fixed,” “attached to,” and the like refer to both direct coupling, fixing, or attaching, as well as indirect coupling, fixing, or attaching through one or more intermediate components or features, unless otherwise specified herein. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, “generally”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. For example, the approximating language may refer to being within a 1, 2, 4, 5, 10, 15, or 20 percent margin in either individual values, range(s) of values and/or endpoints defining range(s) of values. Here and throughout the specification and claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. A “third stream” as used herein means a non-primary air stream capable of increasing fluid energy to produce a minority of total propulsion system thrust. A pressure ratio of the third stream may be higher than that of the primary propulsion stream (e.g., a bypass or propeller driven propulsion stream). The thrust may be produced through a dedicated nozzle or through mixing of an airflow through the third stream with a primary propulsion stream or a core air stream, e.g., into a common nozzle. In certain exemplary embodiments an operating temperature of the airflow through the third stream may be less than a maximum compressor discharge temperature for the engine, and more specifically may be less than 350 degrees Fahrenheit (such as less than 300 degrees Fahrenheit, such as less than 250 degrees Fahrenheit, such as less than 200 degrees Fahrenheit, and at least as great as an ambient temperature). In certain exemplary embodiments these operating temperatures may facilitate heat transfer to or from the airflow through the third stream and a separate fluid stream. Further, in certain exemplary embodiments, the airflow through the third stream may contribute less than 50% of the total engine thrust (and at least, e.g., 2% of the total engine thrust) at a takeoff condition, or more particularly while operating at a rated takeoff power at sea level, static flight speed, 86 degree Fahrenheit ambient temperature operating conditions. Furthermore in certain exemplary embodiments, aspects of the airflow through the third stream (e.g., airstream, mixing, or exhaust properties), and thereby the aforementioned exemplary percent contribution to total thrust, may passively adjust during engine operation or be modified purposefully through use of engine control features (such as fuel flow, electric machine power, variable stators, variable inlet guide vanes, valves, variable exhaust geometry, or fluidic features) to adjust or optimize overall system performance across a broad range of potential operating conditions. The term “disk loading” refers to an average pressure change across a plurality of rotor blades of a rotor assembly, such as the average pressure change across a plurality of fan blades of a fan. The term “rated speed” refers to an operating condition of an engine whereby the engine is operating in the maximum, full load operating condition that is rated by the manufacturer. The term “standard day operating condition” refers to ambient conditions of sea level altitude, 59 degrees Fahrenheit, and 60 percent relative humidity. The term “propulsive efficiency” refers to an efficiency with which the energy contained in an engine's fuel is converted into kinetic energy for the vehicle incorporating the engine, to accelerate it, or to replace losses due to aerodynamic drag or gravity. The term “bypass ratio” refers to a ratio in an engine of an amount of airflow that is bypassed around the engine's ducted inlet to the amount that passes through the engine's ducted inlet. For example, in the embodiment ofFIG.1, discussed below, the bypass ratio refers to an amount of airflow from the fan152that flows over the fan cowl170to an amount of airflow from the fan152that flows through the engine inlet182. The term “corrected tip speed,” with respect to a fan having fan blades, refers to a speed of the fan blades at an outer tip of the fan blades along a radial direction, corrected to correspond to standard day conditions (i.e., the speed the fan blades at their outer tips would rotate at if the upstream temperature corresponded to standard day conditions). Generally, a turbofan engine includes a relatively large fan to provide a desired amount of thrust without overloading the fan blades (i.e., without increasing a disk loading of the fan blades of the fan beyond a certain threshold), and therefore to maintain a desired overall propulsive efficiency for the turbofan engine. Conventional turbofan engine design practice has been to provide a large fan, or rather a high diameter fan, on the engine to provide as much of a total thrust for the turbofan engine as reasonably possible. The objective, when designing the conventional turbofan engine was to maximize a propulsive efficiency of the turbofan engine. A turbofan engine including such a large fan, however, may result in, e.g., problems packaging the turbofan engine on an aircraft, a relatively heavy turbofan engine (particularly for ducted turbofan engines), etc. Further, as the need for turbofan engines to provide more thrust continues, the thermal demands on the turbofan engines correspondingly increases. The inventor of the present disclosure, however, found that for a three stream turbofan engine having a primary fan and a secondary fan, with the secondary fan being a ducted fan providing an airflow to a third stream of the engine, the amount of thrust generation required from the primary fan may be reduced, with the secondary fan providing the difference through the third stream. Such a configuration may maintain a desired overall propulsive efficiently for the turbofan engine, or unexpectedly may in fact increase the over propulsive efficiency of the turbofan engine. The inventor's proceeded in the manner of designing an engine with given primary fan characteristics, secondary fan characteristics, and turbomachine characteristics; checking the propulsive efficiency of the designed turbofan engine; redesigning the turbofan engine with varying primary fan, secondary fan, and turbomachine characteristics; rechecking the propulsive efficiency of the redesigned turbofan engine; etc. during the design of several different types of turbofan engines, including the gas turbine engine described below with reference toFIG.1. During the course of this practice of studying/evaluating various primary fan characteristics, secondary fan characteristics, and turbomachine characteristics considered feasible for best satisfying mission requirements, it was discovered that a certain relationship exists between a percentage of a total turbofan engine thrust provided by a third stream (as defined herein) and the relative sizes of a turbofan's primary to secondary fan, or more particularly a radius ratio of the primary fan to secondary fan. The resulting radius ratio to third-stream thrust relationship, as herein referred to, can be thought of as an indicator of the ability of a turbofan engine to maintain or even improve upon a desired propulsive efficiency via the third stream and, additionally, indicating an improvement in the turbofan engine's packaging concerns and weight concerns, and thermal management capabilities. Referring now toFIG.1, a schematic cross-sectional view of a gas turbine engine is provided according to another example embodiment of the present disclosure. Particularly,FIG.1provides an engine having a rotor assembly with a single stage of unducted rotor blades. In such a manner, the rotor assembly may be referred to herein as an “unducted fan,” or the entire engine100may be referred to as an “unducted engine.” In addition, the engine ofFIG.1includes a third stream extending from the compressor section to a rotor assembly flowpath over the turbomachine, as will be explained in more detail below. For reference, the engine100defines an axial direction A, a radial direction R, and a circumferential direction C. Moreover, the engine100defines an axial centerline or longitudinal axis112that extends along the axial direction A. In general, the axial direction A extends parallel to the longitudinal axis112, the radial direction R extends outward from and inward to the longitudinal axis112in a direction orthogonal to the axial direction A, and the circumferential direction extends three hundred sixty degrees (360°) around the longitudinal axis112. The engine100extends between a forward end114and an aft end116, e.g., along the axial direction A. The engine100includes a turbomachine120and a rotor assembly, also referred to a fan section150, positioned upstream thereof. Generally, the turbomachine120includes, in serial flow order, a compressor section, a combustion section, a turbine section, and an exhaust section. Particularly, as shown inFIG.1, the turbomachine120includes a core cowl122that defines an annular core inlet124. The core cowl122further encloses at least in part a low pressure system and a high pressure system. For example, the core cowl122depicted encloses and supports at least in part a booster or low pressure (“LP”) compressor126for pressurizing the air that enters the turbomachine120through core inlet124. A high pressure (“HP”), multi-stage, axial-flow compressor128receives pressurized air from the LP compressor126and further increases the pressure of the air. The pressurized air stream flows downstream to a combustor130of the combustion section where fuel is injected into the pressurized air stream and ignited to raise the temperature and energy level of the pressurized air. It will be appreciated that as used herein, the terms “high/low speed” and “high/low pressure” are used with respect to the high pressure/high speed system and low pressure/low speed system interchangeably. Further, it will be appreciated that the terms “high” and “low” are used in this same context to distinguish the two systems, and are not meant to imply any absolute speed and/or pressure values. The high energy combustion products flow from the combustor130downstream to a high pressure turbine132. The high pressure turbine128drives the high pressure compressor128through a high pressure shaft136. In this regard, the high pressure turbine128is drivingly coupled with the high pressure compressor128. The high energy combustion products then flow to a low pressure turbine134. The low pressure turbine134drives the low pressure compressor126and components of the fan section150through a low pressure shaft138. In this regard, the low pressure turbine134is drivingly coupled with the low pressure compressor126and components of the fan section150. The LP shaft138is coaxial with the HP shaft136in this example embodiment. After driving each of the turbines132,134, the combustion products exit the turbomachine120through a turbomachine exhaust nozzle140. Accordingly, the turbomachine120defines a working gas flowpath or core duct142that extends between the core inlet124and the turbomachine exhaust nozzle140. The core duct142is an annular duct positioned generally inward of the core cowl122along the radial direction R. The core duct142(e.g., the working gas flowpath through the turbomachine120) may be referred to as a second stream. The fan section150includes a fan152, which is the primary fan in this example embodiment. For the depicted embodiment ofFIG.1, the fan152is an open rotor or unducted fan152. As depicted, the fan152includes an array of fan blades154(only one shown inFIG.1). The fan blades154are rotatable, e.g., about the longitudinal axis112. As noted above, the fan152is drivingly coupled with the low pressure turbine134via the LP shaft138. For the embodiments shown inFIG.1, the fan152is coupled with the LP shaft138via a speed reduction gearbox155, e.g., in an indirect-drive or geared-drive configuration. Moreover, the fan blades154can be arranged in equal spacing around the longitudinal axis112. Each blade154has a root and a tip and a span defined therebetween. Further, each fan blade154defines a fan blade tip radius R1along the radial direction R from the longitudinal axis12to the tip, and a hub radius (or inner radius) R2along the radial direction R from the longitudinal axis12to the base. Further, the fan152, or rather each fan blade154of the fan152, defines a fan radius ratio, RqR, equal to R2divided by R1. As the fan150is the primary fan of the engine100, the fan radius ratio, RqR, of the fan152may be referred to as the primary fan radius ratio, RqRPrim.-Fan. Moreover, each blade154defines a central blade axis156. For this embodiment, each blade154of the fan152is rotatable about their respective central blades axes156, e.g., in unison with one another. One or more actuators158are provided to facilitate such rotation and therefore may be used to change a pitch the blades154about their respective central blades axes156. The fan section150further includes a fan guide vane array160that includes fan guide vanes162(only one shown inFIG.1) disposed around the longitudinal axis112. For this embodiment, the fan guide vanes162are not rotatable about the longitudinal axis112. Each fan guide vane162has a root and a tip and a span defined therebetween. The fan guide vanes162may be unshrouded as shown inFIG.1or, alternatively, may be shrouded, e.g., by an annular shroud spaced outward from the tips of the fan guide vanes162along the radial direction R or attached to the fan guide vanes162. Each fan guide vane162defines a central blade axis164. For this embodiment, each fan guide vane162of the fan guide vane array160is rotatable about their respective central blades axes164, e.g., in unison with one another. One or more actuators166are provided to facilitate such rotation and therefore may be used to change a pitch of the fan guide vane162about their respective central blades axes164. However, in other embodiments, each fan guide vane162may be fixed or unable to be pitched about its central blade axis164. The fan guide vanes162are mounted to a fan cowl170. As shown inFIG.1, in addition to the fan152, which is unducted, a ducted fan184is included aft of the fan152, such that the engine100includes both a ducted and an unducted fan which both serve to generate thrust through the movement of air without passage through at least a portion of the turbomachine120(e.g., without passage through the HP compressor128and combustion section for the embodiment depicted). The ducted fan is rotatable at about the same axis as the fan blade154. The ducted fan184is, for the embodiment depicted, driven by the low pressure turbine134(e.g. coupled to the LP shaft138). In the embodiment depicted, as noted above, the fan152may be referred to as the primary fan, and the ducted fan184may be referred to as a secondary fan. It will be appreciated that these terms “primary” and “secondary” are terms of convenience, and do not imply any particular importance, power, or the like. The ducted fan184includes a plurality of fan blades (not separately labeled inFIG.1). The fan blades of the ducted fan184can be arranged in equal spacing around the longitudinal axis112. Each blade of the ducted fan184has a root and a tip and a span defined therebetween. Further, each fan blade of the ducted fan184defines a fan blade tip radius R3along the radial direction R from the longitudinal axis12to the tip, and a hub radius (or inner radius) R4along the radial direction R from the longitudinal axis12to the base. Further, the ducted fan184, or rather each fan blade of the ducted fan184, defines a fan radius ratio, RqR, equal to R4divided by R3. As the ducted fan184is the secondary fan of the engine100, the fan radius ratio, RqR, of the ducted fan184may be referred to as the secondary fan radius ratio, RqRSec.-Fan. The fan cowl170annularly encases at least a portion of the core cowl122and is generally positioned outward of at least a portion of the core cowl122along the radial direction R. Particularly, a downstream section of the fan cowl170extends over a forward portion of the core cowl122to define a fan flowpath or fan duct172. According to this embodiment, the fan flowpath or fan duct172may be understood as forming at least a portion of the third stream of the engine100. Incoming air may enter through the fan duct172through a fan duct inlet176and may exit through a fan exhaust nozzle178to produce propulsive thrust. The fan duct172is an annular duct positioned generally outward of the core duct142along the radial direction R. The fan cowl170and the core cowl122are connected together and supported by a plurality of substantially radially-extending, circumferentially-spaced stationary struts174(only one shown inFIG.1). The stationary struts174may each be aerodynamically contoured to direct air flowing thereby. Other struts in addition to the stationary struts174may be used to connect and support the fan cowl170and/or core cowl122. In many embodiments, the fan duct172and the core duct142may at least partially co-extend (generally axially) on opposite sides (e.g., opposite radial sides) of the core cowl122. For example, the fan duct172and the core duct142may each extend directly from the leading edge144of the core cowl122and may partially co-extend generally axially on opposite radial sides of the core cowl. The engine100also defines or includes an inlet duct180. The inlet duct180extends between an engine inlet182and the core inlet124/fan duct inlet176. The engine inlet182is defined generally at the forward end of the fan cowl170and is positioned between the fan152and the fan guide vane array160along the axial direction A. The inlet duct180is an annular duct that is positioned inward of the fan cowl170along the radial direction R. Air flowing downstream along the inlet duct180is split, not necessarily evenly, into the core duct142and the fan duct172by a splitter or leading edge144of the core cowl122. The inlet duct180is wider than the core duct142along the radial direction R. The inlet duct180is also wider than the fan duct172along the radial direction R. During operation of the engine100at an operating condition, the engine100generates a total thrust, FnTotal. The operating condition may be operation of the engine100at a rated speed during standard day operating condition. The total thrust is a sum of a first stream thrust, Fn1s(e.g., a primary fan thrust generated by an airflow over the fan cowl170and core cowl122, generated by the fan152), a third stream thrust, Fn3S(e.g., a thrust generated by an airflow through the fan duct172exiting through the fan exhaust nozzle178, generated at least in part by the ducted fan184), and a second stream thrust, Fn2S(e.g., a thrust generated by an airflow through the core duct142exiting through the exhaust nozzle140). Notably, for the embodiment depicted, the engine100includes one or more features to increase an efficiency of the third stream thrust, Fn3S. In particular, the engine100further includes an array of inlet guide vanes186positioned in the inlet duct180upstream of the ducted fan184and downstream of the engine inlet182. The array of inlet guide vanes186are arranged around the longitudinal axis112. For this embodiment, the fan inlet guide vanes186are not rotatable about the longitudinal axis112. Each inlet guide vanes186defines a central blade axis (not labeled for clarity), and is rotatable about their respective central blade axes, e.g., in unison with one another. One or more actuators188are provided to facilitate such rotation and therefore may be used to change a pitch of the inlet guide vanes186about their respective central blades axes. However, in other embodiments, each inlet guide vanes186may be fixed or unable to be pitched about its central blade axis. Further, located downstream of the ducted fan184and upstream of the fan duct inlet176, the engine100includes an array of outlet guide vanes190. As with the array of inlet guide vanes186, the array of outlet guide vanes190are not rotatable about the longitudinal axis112. However, for the embodiment depicted, unlike the array of inlet guide vanes186, the array of outlet guide vanes190are configured as fixed-pitch outlet guide vanes. Further, it will be appreciated that for the embodiment depicted, the fan exhaust nozzle178of the fan duct172is further configured as a variable geometry exhaust nozzle. In such a manner, the engine100includes one or more actuators192for modulating the variable geometry exhaust nozzle. For example, the variable geometry exhaust nozzle may be configured to vary a total cross-sectional area (e.g., an area of the nozzle in a plane perpendicular to the longitudinal axis112) to modulate an amount of thrust generated based on one or more engine operating conditions (e.g., temperature, pressure, mass flowrate, etc. of an airflow through the fan duct172). A fixed geometry exhaust nozzle may also be adopted. The combination of the array of inlet guide vanes186located upstream of the ducted fan184, the array of outlet guide vanes190located downstream of the ducted fan184, and the exhaust nozzle178may result in a more efficient generation of third stream thrust, Fn3S, during one or more engine operating conditions. Further, by introducing a variability in the geometry of the inlet guide vanes186and the exhaust nozzle178, the engine100may be capable of generating more efficient third stream thrust, Fn3S, across a relatively wide array of engine operating conditions, including takeoff and climb (where a maximum total engine thrust FnTotal, is generally needed) as well as cruise (where a lesser amount of total engine thrust, FnTotal, is generally needed). Referring still toFIG.1, in exemplary embodiments, air passing through the fan duct172may be relatively cooler (e.g., lower temperature) than one or more fluids utilized in the turbomachine120. In this way, one or more heat exchangers200may be positioned in thermal communication with the fan duct172. For example, one or more heat exchangers200may be disposed within the fan duct172and utilized to cool one or more fluids from the core engine with the air passing through the fan duct172, as a resource for removing heat from a fluid, e.g., compressor bleed air, oil or fuel. Although not depicted, the heat exchanger200may be an annular heat exchanger extending substantially 360 degrees in the fan duct172(e.g., at least 300 degrees, such as at least 330 degrees). In such a manner, the heat exchanger200may effectively utilize the air passing through the fan duct172to cool one or more systems of the engine100(e.g., lubrication oil systems, compressor bleed air, electrical components, etc.). The heat exchanger200uses the air passing through duct172as a heat sink and correspondingly increases the temperature of the air downstream of the heat exchanger200and exiting the nozzle178. As alluded earlier, the inventor discovered, unexpectedly during the course of turbofan engine design—i.e., designing turbofan engines (both ducted and unducted turbofans) having a variety of different primary fan and secondary fan characteristics, both physical and operational—and evaluating an overall propulsive efficiency, a significant relationship exists between a percentage of a total turbofan engine thrust provided by a third stream (as defined herein) and the relative sizes of a turbofan's primary to secondary fan. The resulting radius ratio to third-stream thrust relationship, as herein referred to, can be thought of as an indicator of the ability of a turbofan engine to maintain or even improve upon a desired propulsive efficiency via the third stream and, additionally, indicating an improvement in the turbofan engine's packaging concerns and weight concerns, and thermal management capabilities. As will be appreciated, higher and lower third stream thrusts change the packaging abilities of the turbofan engine and the thermal sink capabilities of the turbofan engine. For example, increased thrust from an airflow through the third stream generally means more airflow (on a mass flowrate basis) through the third stream, which in turn mean more thermal capacity for such airflow. Further, the inventor found that you provide too little thrust from the third stream, the turbofan engine may be unnecessarily large (and thus more difficult to package) and heavy, and further may not provide a desired amount of thermal sink capabilities. If you provide too much thrust through the third stream, the engine may not fully take advantage of relatively efficient thrust that may be generated by the primary fan. The above relationship may be a function of a bypass ratio of the turbofan engine, which may generally be limited by reasonable engine temperatures, including operating temperatures, such as exhaust gas temperatures (EGT). For example, as will be appreciated in view of the foregoing teaching, a radius of the primary fan relative to a radius of the secondary fan, along with a percentage of a total turbofan engine thrust generated by an airflow through the third stream during operation, are each, in part, a function of the bypass ratio and together characterize the balancing in the relationship noted above. Many aspects of an architecture dictate the bypass ratio of a turbofan engine. For example, the bypass ratio is, in part, a function of a corrected tip speed of the primary fan relative to a corrected tip speed the secondary fan, as well as a specific thrust of the respective primary and secondary fans. The specific thrusts of the primary and secondary fans, in turn, are a function of a pressure ratio of the primary and secondary fans, respectively, and a disk loading (also referred to as a power loading) on the primary and secondary fans, respectively. These factors also affect the balancing in the relationship noted above, as will described in more detail below with reference to an effective fan parameter, EFP. As noted above, the inventor of the present disclosure discovered a relationship between the percentage of engine thrust configured to be provided by the airflow through the third stream and the radius ratio of the primary fan and secondary fan that can result in a turbofan engine maintaining or even improving upon a desired propulsive efficiency, while also improving the turbofan engine's packaging concerns and weight concerns, and also providing desired thermal management capabilities. Utilizing this relationship, the inventor found that the number of suitable or feasible turbofan engine designs incorporating a primary fan and a secondary fan, and defining a third stream, capable of meeting both the propulsive efficiency requirements and packaging, weight, and thermal sink requirements could be greatly diminished, thereby facilitating a more rapid down selection of designs to consider as a turbofan engine is being developed. Such a benefit provides more insight to the requirements for a given turbofan engine well before specific technologies, integration and system requirements are developed fully. It avoids late-stage redesign. The desired relationship is represented by the following Equation (1): R1R3=(EFP)(1-RqRSec.-Fan2)(1-RqRPrim.-Fan2)(1%Fn3S-1);Equation(1) where R1is a tip radius of the primary fan, R2is a hub radius of the primary fan, R3is a tip radius of the secondary fan, R4is a hub radius of the secondary fan, RqRPrim.-Fanis the ratio of R2to R1, RqRSec.-Fanis the ratio of R4to R3, % Fn3Sis the percentage of thrust through the third stream relative to a total thrust of the engine (e.g., for the embodiment ofFIG.1, Fn3Sdivided by FnTotal), and EFP is called an effective fan parameter. For the purposes of Equation (1), % Fn3Sis defined while operating the engine at a rated speed during standard day operating conditions. EFP is a function of a corrected tip speed of the primary fan, a corrected tip speed of the secondary fan, a disk loading of the primary fan, and a disk loading of the secondary fan. EFP, by taking into account the corrected tip speeds of the primary and secondary fans, accounts for such factors as the specific engine configuration (e.g., geared, direct drive, etc.), which may have some influence on the relationship between tip radius ratio (R1to R3) and the percent thrust through the third stream (% Fn3S) for a turbofan engine having a desired propulsive efficiency. The relationship of these contributing factors to EFP to the tip radius ratio (R1to R3) and the percent thrust through the third stream (% Fn3S) for a turbofan engine is described in more detail above. Values for R1/R3and the corresponding values of the influencing characteristics of an engine defined by Equation (1) are set forth in TABLE 1: TABLE 1Ranges appropriate for usingSymbolDescriptionEq. (1)R1/R3Tip radius ratioabout 2 to about 10, such asabout 2 to about 7, such as about3 to about 5, such as at least 3.5,such as 3.7, such as at least 4,such as up to about 10, such asup to about 7RqRSec.-FanSecondary fan radiusabout 0.2 to about 0.7, such asratioabout 0.35 to about 0.5RqRPrim.-FanPrimary fan radius ratioabout 0.2 to about 0.4, such asabout 0.25 to about 0.35EFPEffective fan parameterabout 1.5 to about 11, such asabout 2 to about 4.5, such asabout 2.5 to about 4, such asabout 3 to about 3.5VCPrim.-Corrected primary fanabout 500 feet per second (fps) toFantip speedabout 2,000 fps, such as about750 fps to about 1,750 fpsVCSec.-FanCorrected secondaryabout 500 feet per second (fps) tofan tip speedabout 2,000 fps, such as about750 fps to about 1,750 fps% Fn3SPercent thrust throughabout 1% to about 50%, such asthird streamabout 3% to about 30%, such asabout 5% to about 20%, such asat least about 7%, such as at leastabout 10%, such as at least about15%, and below about 50% FIGS.2A through2D and3illustrate gas turbine engines in accordance with one or more exemplary embodiments of the present disclosure, showing the relationships between the tip radius ratio and percent thrust through the third stream. In particular,FIGS.2A through2Dprovides a table including numerical values corresponding to several of the plotted gas turbine engines inFIG.3.FIG.3is a plot of gas turbine engines in accordance with one or more exemplary embodiments of the present disclosure, showing the relationships between the tip radius ratio (R1to R3; Y-Axis) and the percent thrust through the third stream (% Fn3S; X-Axis). Notably, inFIG.3, a first range and a second range are provided. The first range may correspond to an EFP of between 1.5 and 11, with % Fn3Sequal to between about 2% and about 50%. Such may result in an engine having a desired propulsive efficiency. The second range may correspond to an EFP of about 2.5 and about 4, with % Fn3Sequal to between about 5% and about 20%. Such may result in an engine having a more preferred propulsive efficiency. As will be appreciated from the description herein, various embodiments of a gas turbine engine are provided. Certain of these embodiments may be an unducted, single rotor gas turbine engine, or a ducted turbofan engine. An example of a ducted turbofan engine can be found in U.S. patent application Ser. No. 16/811,368 (Published as U.S. Patent Application Publication No. 2021/0108597), filed Mar. 6, 2020 (FIG.10, Paragraph [0062], et al.; including an annular fan case13surrounding the airfoil blades21of rotating element20and surrounding vanes31of stationary element30; and including a third stream/fan duct73(shown inFIG.10, described extensively throughout the application)). Various additional aspects of one or more of these embodiments are discussed below. These exemplary aspects may be combined with one or more of the exemplary gas turbine engine(s) discussed above with respect to the figures. For example, in some embodiments of the present disclosure, the engine may include a heat exchanger located in an annular duct, such as in a third stream. The heat exchanger may extend substantially continuously in a circumferential direction of the gas turbine engine (e.g., at least about 300 degrees, such as at least about 330 degrees). In one or more of these embodiments, a threshold power or disk loading for a fan (e.g., an unducted single rotor or primary forward fan) may range from 25 horsepower per square foot (hp/ft2) or greater at cruise altitude during a cruise operating mode. In particular embodiments of the engine, structures and methods provided herein generate power loading between 80 hp/ft2and 160 hp/ft2or higher at cruise altitude during a cruise operating mode, depending on whether the engine is an open rotor or ducted engine. In various embodiments, an engine of the present disclosure is applied to a vehicle with a cruise altitude up to approximately 65,000 ft. In certain embodiments, cruise altitude is between approximately 28,000 ft and approximately 45,000 ft. In still certain embodiments, cruise altitude is expressed in flight levels based on a standard air pressure at sea level, in which a cruise flight condition is between FL280 and FL650. In another embodiment, cruise flight condition is between FL280 and FL450. In still certain embodiments, cruise altitude is defined based at least on a barometric pressure, in which cruise altitude is between approximately 4.85 psia and approximately 0.82 psia based on a sea level pressure of approximately 14.70 psia and sea level temperature at approximately 59 degrees Fahrenheit. In another embodiment, cruise altitude is between approximately 4.85 psia and approximately 2.14 psia. It should be appreciated that in certain embodiments, the ranges of cruise altitude defined by pressure may be adjusted based on a different reference sea level pressure and/or sea level temperature. As such, it will be appreciated that an engine of such a configuration may be configured to generate at least about 25,000 pounds and less than about 80,000 of thrust during operation at a rated speed, such as between about 25,000 and 50,000 pounds of thrust during operation at a rated speed, such as between about 25,000 and 40,000 pounds of thrust during operation at a rated speed. In various exemplary embodiments, the fan may include twelve (12) fan blades. From a loading standpoint, such a blade count may allow a span of each blade to be reduced such that the overall diameter of the primary fan may also be reduced (e.g., to about twelve feet in one exemplary embodiment). That said, in other embodiments, the fan may have any suitable blade count and any suitable diameter. In certain suitable embodiments, the fan includes at least eight (8) blades. In another suitable embodiment, the fan may have at least twelve (12) blades. In yet another suitable embodiment, the fan may have at least fifteen (15) blades. In yet another suitable embodiment, the fan may have at least eighteen (18) blades. In one or more of these embodiments, the fan includes twenty-six (26) or fewer blades, such as twenty (20) or fewer blades. Further, in certain exemplary embodiments, the rotor assembly may define a rotor diameter (or fan diameter) of at least 10 feet, such as at least 11 feet, such as at least 12 feet, such as at least 13 feet, such as at least 15 feet, such as at least 17 feet, such as up to 28 feet, such as up to 26 feet, such as up to 24 feet, such as up to 18 feet. In various embodiments, it will be appreciated that the engine includes a ratio of a quantity of vanes to a quantity of blades that could be less than, equal to, or greater than 1:1. For example, in particular embodiments, the engine includes twelve (12) fan blades and ten (10) vanes. In other embodiments, the vane assembly includes a greater quantity of vanes to fan blades. For example, in particular embodiments, the engine includes ten (10) fan blades and twenty-three (23) vanes. For example, in certain embodiments, the engine may include a ratio of a quantity of vanes to a quantity of blades between 1:2 and 5:2. The ratio may be tuned based on a variety of factors including a size of the vanes to ensure a desired amount of swirl is removed for an airflow from the primary fan. Additionally, in certain exemplary embodiments, where the engine includes the third stream and a mid-fan (a ducted fan aft of the primary, forward fan), a ratio R1/R2may be between about 1 and 10, or 2 and 7, or at least about 3.3, at least about 3.5, at least about 4 and less than or equal to about 7, where R1is the radius of the primary fan and R2is the radius of the mid-fan. It should be appreciated that various embodiments of the engine, such as the single unducted rotor engine depicted and described herein, may allow for normal subsonic aircraft cruise altitude operation at or above Mach 0.5. In certain embodiments, the engine allows for normal aircraft operation between Mach 0.55 and Mach 0.85 at cruise altitude. In still particular embodiments, the engine allows for normal aircraft operation between Mach 0.75 and Mach 0.85. In certain embodiments, the engine allows for rotor blade tip speeds at or less than 750 feet per second (fps). In other embodiments, the rotor blade tip speed at a cruise flight condition can be 650 to 900 fps, or 700 to 800 fps. A fan pressure ratio (FPR) for the fan of the fan assembly can be 1.04 to 1.20, or in some embodiments 1.05 to 1.1, or in some embodiments less than 1.08, as measured across the fan blades at a cruise flight condition. In order for the gas turbine engine to operate with a fan having the above characteristics to define the above FPR, a gear assembly may be provided to reduce a rotational speed of the fan assembly relative to a driving shaft (such as a low pressure shaft coupled to a low pressure turbine). In some embodiments, a gear ratio of the input rotational speed to the output rotational speed is greater than 4.1. For example, in particular embodiments, the gear ratio is within a range of 4.1 to 14.0, within a range of 4.5 to 14.0, or within a range of 6.0 to 14.0. In certain embodiments, the gear ratio is within a range of 4.5 to 12 or within a range of 6.0 to 11.0. As such, in some embodiments, the fan can be configured to rotate at a rotational speed of 700 to 1500 rpm at a cruise flight condition, while the power turbine (e.g., the low-pressure turbine) is configured to rotate at a rotational speed of 2,500 to 15,000 rpm at a cruise flight condition. In particular embodiments, the fan can be configured to rotate at a rotational speed of 850 to 1,350 rpm at a cruise flight condition, while the power turbine is configured to rotate at a rotational speed of 5,000 to 10,000 rpm at a cruise flight condition. With respect to a turbomachine of the gas turbine engine, the compressors and/or turbines can include various stage counts. As disclosed herein, the stage count includes the number of rotors or blade stages in a particular component (e.g., a compressor or turbine). For example, in some embodiments, a low pressure compressor may include 1 to 8 stages, a high-pressure compressor may include 8 to 15 stages, a high-pressure turbine may include 1 to 2 stages, and/or a low pressure turbine (LPT) may include 3 to 7 stages. In particular, the LPT may have 4 stages, or between 4 and 7 stages. For example, in certain embodiments, an engine may include a one stage low pressure compressor, an 11 stage high pressure compressor, a two stage high pressure turbine, and 4 stages, or between 4 and 7 stages for the LPT. As another example, an engine can include a three stage low-pressure compressor, a 10 stage high pressure compressor, a two stage high pressure turbine, and a 7 stage low pressure turbine. A core engine is generally encased in an outer casing defining one half of a core diameter (Dcore), which may be thought of as the maximum extent from a centerline axis (datum for R). In certain embodiments, the engine includes a length (L) from a longitudinally (or axial) forward end to a longitudinally aft end. In various embodiments, the engine defines a ratio of L/Dcore that provides for reduced installed drag. In one embodiment, L/Dcore is at least 2. In another embodiment, L/Dcore is at least 2.5. In some embodiments, the L/Dcore is less than 5, less than 4, and less than 3. In various embodiments, it should be appreciated that the L/Dcore is for a single unducted rotor engine. The reduced installed drag may further provide for improved efficiency, such as improved specific fuel consumption. Additionally, or alternatively, the reduced drag may provide for cruise altitude engine and aircraft operation at the above describe Mach numbers at cruise altitude. Still particular embodiments may provide such benefits with reduced interaction noise between the blade assembly and the vane assembly and/or decreased overall noise generated by the engine by virtue of structures located in an annular duct of the engine. Additionally, it should be appreciated that ranges of power loading and/or rotor blade tip speed may correspond to certain structures, core sizes, thrust outputs, etc., or other structures at the core engine and the than. However, as previously stated, to the extent one or more structures provided herein may be known in the art, it should be appreciated that the present disclosure may include combinations of structures not previously known to combine, at least for reasons based in part on conflicting benefits versus losses, desired modes of operation, or other forms of teaching away in the art. Although depicted above as an unshrouded or open rotor engine in the embodiments depicted above, it should be appreciated that aspects of the disclosure provided herein may be applied to shrouded or ducted engines, partially ducted engines, aft-fan engines, or other gas turbine engine configurations, including those for marine, industrial, or aero-propulsion systems. Certain aspects of the disclosure may be applicable to turbofan, turboprop, or turboshaft engines. However, it should be appreciated that certain aspects of the disclosure may address issues that may be particular to unshrouded or open rotor engines, such as, but not limited to, issues related to gear ratios, fan diameter, fan speed, length (L) of the engine, maximum diameter of the core engine (Dcore) of the engine, L/Dcore of the engine, desired cruise altitude, and/or desired operating cruise speed, or combinations thereof. This written description uses examples to disclose the present disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. Further aspects are provided by the subject matter of the following clauses: A gas turbine engine defining a centerline and a circumferential direction, the gas turbine engine comprising: a turbomachine comprising a compressor section, a combustion section, and a turbine section arranged in serial flow order, the turbomachine defining a working gas flowpath and a fan duct flowpath; a primary fan driven by the turbomachine defining a primary fan tip radius R1and a primary fan hub radius R2; a secondary fan located downstream of the primary fan and driven by the turbomachine, at least a portion of an airflow from the primary fan configured to bypass the secondary fan, the secondary fan defining a secondary fan tip radius R3and a secondary fan hub radius R4, wherein the secondary fan is configured to provide a fan duct airflow through the fan duct flowpath during operation to generate a fan duct thrust, wherein the fan duct thrust is equal to % Fn3Sof a total engine thrust during operation of the gas turbine engine at a rated speed during standard day operating conditions; wherein a ratio of R1to R3equals (EFP)(1-RqRSec.-Fan2)(1-RqRPrim.-Fan2)(1%Fn3S-1); wherein EFP is between 1.5 and 11, wherein RqRPrim.-Fanis a ratio of R2to R1, and wherein RqRSec.-Fanis a ratio of R4to R3. The gas turbine engine of one or more of these clauses, wherein the ratio of R1to R3is between about 2 and about 10, such as between about 2 and about 7. The gas turbine engine of one or more of these clauses, wherein the ratio of R1 to R3 is between about 3 and about 5. The gas turbine engine of one or more of these clauses, wherein EFP is between about 2.5 and about 4, and wherein % Fn3Sis greater than or equal to about 5% and less than or equal to about 20%. The gas turbine engine of one or more of these clauses, wherein RqRPrim.-Fanis between 0.2 and 0.4. The gas turbine engine of one or more of these clauses, wherein RqRPrim.-Fanis between 0.25 and 0.35. The gas turbine engine of one or more of these clauses, wherein RqRSec.-Fan is between 0.2 and 0.7. The gas turbine engine of one or more of these clauses, wherein RqRSec.-Fan is between 0.35 and 0.5. The gas turbine engine of one or more of these clauses, wherein EFP is between A2 and B2, wherein the primary fan defines a primary fan corrected tip speed during operation of the gas turbine engine at the rated speed during standard day operating conditions, wherein the secondary fan defines a secondary fan corrected tip speed during operation of the gas turbine engine at the rated speed during standard day operating conditions, wherein the primary fan corrected tip speed is between 500 feet per second and 2,000 feet per second, and wherein the secondary fan corrected tip speed is between 500 feet per second and 2,000 feet per second. The gas turbine engine of one or more of these clauses, wherein % Fn3Sis between 1% and 50%. The gas turbine engine of one or more of these clauses, wherein % Fn3Sis between 3% and 30%. The gas turbine engine of one or more of these clauses, wherein % Fn3Sis between 5% and 20%. The gas turbine engine of one or more of these clauses, wherein the fan duct flowpath defines an outlet, and wherein the gas turbine engine further comprises: a variable geometry component associated with the secondary fan, wherein the variable geometry component is a stage of variable inlet guide vanes located immediately upstream of the secondary fan, a variable exhaust nozzle located at the outlet of the fan duct flowpath, or both. The gas turbine engine of one or more of these clauses, wherein the primary fan is an unducted fan. The gas turbine engine of one or more of these clauses, wherein the gas turbine engine defines a bypass airflow passage, wherein the primary fan is configured to provide a first portion of a primary fan airflow to the bypass airflow passage and a second portion of the primary fan airflow to the secondary fan, and wherein the secondary fan is configured to provide a first portion of a secondary fan airflow to the fan duct flowpath as the fan duct airflow and a second portion of the secondary fan airflow to the working gas flowpath. The gas turbine engine of one or more of these clauses, further comprising: a heat exchanger positioned in thermal communication with the fan duct flowpath. The gas turbine engine of one or more of these clauses, further comprising: an array of inlet guide vanes located immediately upstream of the secondary fan. The gas turbine engine of one or more of these clauses, further comprising: an array of outlet guide vanes located immediately downstream of the secondary fan and upstream of the fan duct. The gas turbine engine of one or more of these clauses, further comprising: a variable geometry exhaust nozzle located at an exit of the fan duct. The gas turbine engine of one or more of these clauses, further comprising: a fan cowl surrounding the secondary fan located downstream of the primary fan, the fan cowl defining in part an engine inlet located downstream of the primary fan; wherein the turbomachine further comprises a core cowl surrounding at least in part the compressor section, the combustion section, and the turbine section, and wherein the fan duct is defined between the core cowl and the fan cowl. | 51,210 |
11859517 | DETAILED DESCRIPTION OF THE DISCLOSURE The present subject matter will now be described more fully hereinafter with reference to exemplary embodiments thereof. These exemplary embodiments are described so that this disclosure will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art. Indeed, the subject matter can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. As used in the specification, and in the appended claims, the singular forms “a”, “an”, “the”, include plural referents unless the context clearly dictates otherwise. In one or more embodiments, the present disclosure provides for cogeneration of power and one or more further products (e.g., a chemical entity or entities and/or heat) through operation of a power production cycle and treatment of a high pressure stream, such as a syngas stream. The present systems and methods thus can utilize heat transfer between two or more processes or processing units to improve efficiency of one or more of the processes. Likewise, the present systems and methods can beneficially provide one or more product streams at a reduced cost compared to known methods for preparing such products. As used herein syngas (or synthesis gas) is understood to reference a chemical mixture comprising at least hydrogen and carbon monoxide. The syngas is typically a gaseous mixture, although a mixed-phase syngas may also be utilized. Moreover, although it can be preferable to utilize a substantially pure syngas stream (e.g., comprising 95% or greater, 99% or greater, or 99.5% or greater hydrogen and carbon monoxide), the present disclosure does not necessarily exclude the presence of further chemical moieties in the syngas being utilized. The syngas can be subjected to one or more treatment steps as otherwise described herein to generate one or more desired chemical products, and the treatment steps can include utilization of one or more streams generated in a co-operated power production cycle. A power production cycle as discussed herein, or a power production plant, can incorporate a variety of elements for carrying out the power production cycle. Non-limiting examples of elements that may be included in a power production plant (and method of operation thereof) according to the present disclosure are described in U.S. Pat. Nos. 8,596,075, 8,776,532, 8,869,889, 8,959,887, 8,986,002, 9,062,608, 9,068,743, 9,410,481, 9,416,728, 9,546,814, 10,018,115, and U. S. Pat. Pub. No. 2012/0067054, the disclosures of which are incorporated herein by reference. In one or more embodiments, a power production cycle useful according to the present disclosure can include any system and method wherein CO2(particularly supercritical CO2— or sCO2) is used in a work stream. As a non-limiting example, a recycle CO2stream is provided at high temperature and high pressure, is input to a combustor wherein a carbonaceous fuel is combusted in oxygen, is expanded across a turbine to produce power, is cooled in a heat exchanger, is purified to remove water and any other impurities, is pressurized, is re-heated using the heat taken from the turbine exhaust, and is again passed to the combustor to repeat the cycle. Such system and method are beneficial in that all fuel and combustion derived impurities, excess CO2, and water are removed as a liquid or a solid (e.g., ash), and there is virtually zero atmospheric emission of any streams. The system and method achieves high efficiency through, for example, the use of low temperature level (i.e., less than 500° C.) heat input after the recycle CO2stream has been re-pressurized and before combustion. A power production cycle according to the present disclosure can include more steps or fewer steps than described above and can generally include any cycle wherein a high pressure recycle CO2stream is expanded for power production and recycled again for further power production. As used herein, a high pressure recycle CO2stream can have a pressure of at least 100 bar (10 MPa), at least 200 bar (20 MPa), or at least 300 bar (30 MPa). A high pressure recycle CO2stream can, in some embodiments, have a pressure of about 100 bar (10 MPa) to about 500 bar (50 MPa), about 150 bar to about 450 bar (45 MPa), or about 200 bar (20 MPa) to about 400 bar (40 MPa). Reference to a high pressure recycle CO2stream herein may thus be a CO2stream at a pressure within the foregoing ranges. Such pressures also apply to references to other high pressure streams described herein, such as a high pressure work stream comprising CO2. In some embodiments, a power production cycle can be a cycle wherein a recycled CO2stream is subjected to repeated compression, heating, combustion, expansion for power production, and cooling. As a non-limiting example, a power production system100and method of use thereof is illustrated inFIG.1. As illustrated therein, a power production cycle can include a combustor115where a carbonaceous fuel feed112and an oxidant feed114are combusted in the presence of a recycle CO2stream138to form a high pressure, high temperature combustion product stream117that is expanded in a turbine120to produce power with a generator145. The exhaust stream122from the turbine120at high temperature is cooled in a recuperative heat exchanger125to produce a low pressure, low temperature CO2stream127that is passed through a separator130with condensed products132(e.g., water) and a substantially pure recycle CO2stream133exiting therefrom. A substantially pure recycle CO2stream can comprise at 95%, at least 98%, at least 99%, or at least 99.5% molar CO2. The substantially pure recycle CO2stream133is compressed in compressor135to form the high pressure recycle CO2stream138(e.g., having a pressure in a range as described above) that is passed to the recuperative heat exchanger125where it is heated against the cooling turbine exhaust stream122. A power production cycle such as shown inFIG.1can be advantageous for use according to the present disclosure at least in part because of the ability to recuperate a significant amount of the heat from the turbine exhaust122for use in re-heating the recycle CO2stream after compression and before passage to the combustor115. Efficiency, however, can be limited by the ability to add enough heat to raise the temperature of the recycle CO2stream138exiting the hot end of the recuperative heat exchanger125to be sufficiently close to the temperature of the turbine exhaust122entering the hot end of the recuperative heat exchanger. The need for input of additional heating is identified in U.S. Pat. No. 8,596,075, and various possible sources of low grade heat (e.g., at a temperature of less than about 500° C.) are identified. In some embodiments, a power production cycle for use as described herein can include any power production cycle whereby a working fluid comprising CO2is repeatedly cycled at least through stages of compressing, heating, expansion, and cooling. In various embodiments, a power production cycle for use according to the present disclosure may include combinations of the following steps:combustion of a carbonaceous fuel with an oxidant in the presence of a recycled CO2stream to provide a combustion product stream at a temperature of at least about 500° C. or at least about 700° C. (e.g., about 500° C. to about 2000° C. or about 600° C. to about 1500° C.) and a pressure of at least about 100 bar (10 MPa) or at least about 200 bar (20 MPa) (e.g., about 100 bar (10 MPa) to about 500 bar (50 MPa) or about 150 bar (15 MPa) to about 400 bar (40 MPa));expansion of a high pressure recycled CO2stream (e.g., at a pressure as noted above) across a turbine for power production;cooling of a high temperature recycled CO2stream (e.g., at a pressure as noted above), particularly of a turbine discharge stream, in a recuperative heat exchanger;condensing of one or more combustion products (e.g., water) in a condenser, the combustion products being present particularly in a combustion product stream that has been expanded and cooled;separating water and/or further materials from CO2to form a recycled CO2stream;compressing a recycled CO2stream to a high pressure (e.g., a pressure as noted above), optionally being carried out in multiple stages with optional inter-cooling to increase stream density; andheating a compressed recycled CO2stream in a recuperative heat exchanger, particularly heating against a cooling turbine exhaust stream. In further embodiments, the present disclosure also relates to power production systems. In particular, such systems can comprise one or more pumps or compressors configured to compress a CO2stream to a high pressure as described herein. The systems can comprise one or more valves or splitters configured to divide the compressed CO2stream into at least a first portion CO2stream and a second portion CO2stream. The systems can comprise a first heat exchanger (or heat exchange unit comprising a plurality of sections) configured to heat a CO2stream against a high temperature turbine discharge stream and optionally provide heating to one or more further streams. The systems can comprise at least one turbine configured to expand a CO2containing stream to produce power. The systems can comprise one or more transfer elements configured to transfer heat between one or more streams. The systems can comprise a combustor configured to combust a carbonaceous fuel in an oxidant in the presence of the CO2stream. The systems of the present disclosure can comprise at least one compressor configured to compress a CO2stream to a high pressure as described herein, at least one combustor downstream from the compressor, at least one turbine downstream from the combustor and upstream from the compressor, and at least one heat exchanger positioned to receive a stream from the at least one compressor and to receive a separate stream from the at least one turbine. Optionally, a separator can be positioned downstream from the heat exchanger and upstream from the compressor. Further optionally, a compressor can be positioned upstream from the compressor and downstream from the first heat exchanger. The system can further comprise one or more valves or splitters as necessary. As previously discussed, a power production cycle, being configured according to any useful embodiments including, but not limited, to those described above, can be combined with forming and/or processing of a syngas stream in a manner such that further, useful products are provided in addition to the power attributable to the power production cycle. Systems and methods suitable for such cogeneration of power and one or more further products is illustrated according to one or more embodiments of the present disclosure inFIG.2. A power cycle201is illustrated inFIG.2and can be any power cycle configured for production of power and being capable of receiving and providing one or more heated streams and, optionally, carbon dioxide. Thus, the power cycle201, may be a supercritical CO2power cycle utilizing components and operations as already described above, and the power cycle may include one or more of the components described in relation toFIG.1. The power cycle201receives fuel in line202from a fuel source204, receives oxidant through line211from an oxidant source210, provides power205(e.g., electricity) as an output, and optionally can provide a CO2stream through line207as a further output. The oxidant source210may be, for example, an air separation unit (ASU) configured for providing substantially pure oxygen (e.g., at least 95%, at least 98%, at least 99%, or at least 99.5% molar O2); however, other oxygen sources or oxidant sources may be utilized. The oxidant source210may likewise be a nitrogen source. For example, and ASU can be effective to separate air into a stream of predominately oxygen and a stream of predominately nitrogen. Thus, in some embodiments, the same unit can be configured to be one or both of an oxidant source and a nitrogen source. Pressurized raw syngas can be processed to generate one or more end products, and the syngas can be provided from a variety of sources, such as being generated by gasification or reforming of a suitable feedstock. The pressurized, raw syngas can be provided into the process illustrated inFIG.2as a preformed, sourced material. Alternatively, as illustrated, the syngas optionally can be formed directly as part of the overall process. As shown, fuel in line221, steam in line223, and oxidant in line213are introduced to a syngas generation unit220to provide the pressurized, raw syngas stream in line225. As illustrated, the syngas generation unit220may be a single component or can include a plurality of components that are configured to provide the pressurized, raw syngas stream. In some embodiments, the syngas generation unit220can be configured to receive heating from the power cycle201. As illustrated by line(s)224, one or more streams may be passed between the power cycle201and the syngas generation unit220so that heat from the power cycle may be added to the syngas generation unit. For example, heating from a turbine exhaust stream from the power cycle201may be transferred directly (e.g., turbine being passed to a heat exchanger in the syngas generation unit220) or indirectly (e.g., a heat transfer fluid can be used to transfer heat) through line(s)224. Line224is illustrated as dashed to show that it is optional, and the arrow illustrates the direction in which heat is transferred. The pressurized, raw syngas in line225can be processed in cooling/conditioning unit230, and such processing can include only cooling, can include only one or more conditioning steps, or can include both of cooling and conditioning. For example, the raw syngas can be cooled against a high pressure stream of a heat transfer medium (such as carbon dioxide or even a fuel stream) taken from the power cycle201, and this heat transfer medium can be utilized for heat recuperation and additional power generation. As illustrated inFIG.2, line234is shown dashed to illustrate that it is optional, and the arrow illustrates the direction in which heat is transferred. In other embodiments, cooling can be carried out by additional or alternative processes. For example, the steam in line223may be at least partially generated by heating a water stream using heat from the cooling/conditioning unit230. In some embodiments, conditioning of the syngas can be carried out sequentially with cooling. For example, the cooled syngas can then be purified, such as by applying one or more of dewatering, filtering for fine particulate matter, removal of soluble acid gas, and heavy metal removal. As such, it is understood that the cooling/conditioning unit may comprise a plurality of individual components, such as one or more filter units, one or more liquid separation units, one or more membrane units, and the like, and such optional units are illustrated as230a,230b, and230c. The cooling/conditioning unit230thus may provide, through line236, one or more of hydrogen sulfide (H2S), CO2, water, tar, particulates, heavy metals, and/or similar materials that can be separated from the raw syngas. Optionally, clean syngas may be used as all or part of the fuel for the power cycle201in line202. The clean syngas is shown in line237being combined with line202, but it is understood that line237may pass directly to a component of the power cycle201, such as a combustor. The at least partially purified syngas stream in line239(and optionally in line237), preferably will be nominally dry and cooled. In one or more embodiments, all or part of the purified syngas is transferred through line239to a hydrogen separation unit240, which itself can include one or more separation components. The hydrogen separation unit240, for example, may include a gas membrane, a pressure swing absorber (PSA), and/or another gas separation system that can be adapted to or configured to favor the separation of hydrogen via its small kinetic diameter and partial pressure. For example, so-called prism membranes (available from Air Products) can be particularly suitable for such separation. In general, the relative permeation rate of gas molecules through such membranes (in descending order) is H2O, H2, NH3, CO2, H2S, O2, Ar, CO, N2, CH4, C2H4, and C3H8. The membrane and/or further separation component can enable the formation of two separate flows from the hydrogen separation unit. A first stream in line243can be predominantly hydrogen (e.g., greater than 50%, greater than 60%, greater than 75%, greater than 85%, or greater than 90% molar hydrogen). A second stream in line245can comprise any one or more of hydrogen, N2, Ar, CO, CO2, H2S, COS, CH4, C2H4, C3H8, and any further compounds that may have been part of the original syngas input. Preferably, the second stream will be hydrogen lean (e.g., less than 50%, less than 25%, or less than 10% molar) and, as such, the second stream can be referenced as being a hydrogen-depleted stream. Such a hydrogen-depleted stream typically can comprise some combination of H2(preferably in a low concentration), CO2, CO, CH4, N2, and Ar. In this manner, the present systems and methods can provide one or more carbonaceous compounds that may be separated from a hydrogen containing stream without the need for dedicated removal equipment targeting the non-hydrogen species' groups. Similarly, the present disclosure can be useful to provide handling of carbonaceous compounds including export/disposal, wherein such handling is provided by the power cycle combustion and compression regimes. Likewise, the present systems and methods can be useful to reduce/eliminate water consumption for the production of hydrogen in that hydrogen production via WGS is not required (although it may be optionally utilized if desired). Specifically, this can be the case since residual feedstock is used as power cycle fuel. The power cycle serves as a means of balancing lost revenue that would have been generated by additional hydrogen as well as a CAPEX offset. In one or more embodiments, the H2product provided through line243can be separated using H2pressure swing absorption (PSA) technology. In such embodiments, the processing, cleanup, and cooling of the syngas may be carried out in the cooling/conditioning unit230such that syngas with a required H2content and a desired impurity level can be present in line239for input at the inlet of a PSA unit. This can include, for example, carrying out one or more of the following processing steps in the cooling/conditioning unit230or in one or more further units combined therewith: carrying out sour or sweet water gas shift; providing for particulate and/or heavy metal removal; carrying our carbonyl sulfide (COS) hydrolysis; carrying out removal of sulfurous material, such as H2S, in an acid gas removal step; and partial or deep removal of CO2. It can be preferred to carry out such separation steps such that the stream in line239entering the hydrogen separation unit240has a hydrogen content of at least 60% by volume. It is possible to achieve a high hydrogen recovery efficiency using PSA separation when the feed stream entering the unit240has a relatively high hydrogen content with low contaminate levels, the presence of which may be detrimental to the lifetime of adsorbent material used in the PSA. It is generally desirable to achieve an H2recovery efficiency of greater than 75%, greater than 80%, or greater than 85% in the H2PSA unit, which such unit it utilized. The first stream in line243exiting the hydrogen separation unit (comprising predominately hydrogen gas) can be sent on for final processing, if needed, and then can be used as a chemical feedstock in adjacent facilities and/or exported. The second stream in line245(i.e., the hydrogen-depleted stream) exiting the hydrogen separation unit240can be input as at least a portion of the fuel in line202in the co-operated power cycle201. Line245thus may combine with line202or be input directly to a component of the power cycle201. The second gas stream can be compressed to a sufficiently high pressure (potentially being pre-heated against the raw syngas as noted previously) and combusted with nominally pure oxygen in the power cycle's combustor/turbine. Line245thus may be input to a compressor (see element135) of the power cycle201and/or a like compressor may be positioned directly in line245. The resulting turbine exhaust gas in the power cycle201thus can be a mixture of predominantly carbon dioxide and water with traces of (but not exclusively) O2, N2, Ar, NO, and SO2. Referring toFIG.1as an example embodiment of the power cycle201), the turbine exhaust gas can be cooled (e.g., in a recuperative heat exchanger train), such as down to a temperature approaching ambient temperature. Upon the exit of the heat recovery train, the exhaust gas in line122can be provided to a water separator130for one or more purification steps. The purification can include removal of NOx and SOx impurities to provide a nominally dry and substantially pure stream of carbon dioxide in line133. A suitable purification unit can be, for example, a DeSNOx unit470as described in relation toFIG.4below. The substantially pure carbon dioxide can be pressurized (e.g., as part of the power cycle's working fluid recovery process). If desired, sulfur species can also be removed from the syngas via conventional acid gas removal processes prior to syngas combustion. A portion of the pressurized carbon dioxide can be drawn from the working fluid (e.g., in line207) in order to maintain a mass balance with the fuel and oxygen entering the power production cycle. The withdrawn carbon dioxide stream may be vented, sequestered, or sent on for use as a feedstock in a downstream chemical process, such as urea production. In some embodiments, the second stream exiting the hydrogen separation unit240in line245may be further processed in a CO2separation unit250to recover and purify at least a portion of its CO2content. The CO2separation unit250is preferably a low temperature unit. A low temperature CO2separation unit can be a unit that is configured to cool at least a portion of the second stream exiting the hydrogen separation unit (i.e., a hydrogen-depleted stream) to a temperature sufficient for separation of any carbon dioxide therein so as to be in a liquefied form. For example, a suitable low temperature CO2separation unit can be one that is configured to cool at least a portion of the second stream to a temperature that is above but within about 50° C., within about 40° C. or within about 30° C. of the freezing temperature of the second stream. More particularly, the low temperature CO2separation unit can be configured to cool to a temperature that is about 2° C. to about 25° C., about 2° C. to about 15° C., or about 1° C. to about 5° C. greater than the freezing temperature of the second stream. In such embodiments, it can be desirable to design the overall process such that the CO2content of the stream in line245can be at least 40% by volume of the total output from the hydrogen separation unit240. This can be beneficial to reduce the overall cost of CO2separation in a low temperature system. In some embodiments, a preferred CO2separation process can implement CO2separation as a liquid at a low temperature within about 1° C. to about 5° C. of the freezing temperature of the compressed dried gas mixture in line245. The residual CO2partial pressure in the separated uncondensed gas stream will be at a pressure in the range of about 6 bar to about 7 bar. The low pressure gas stream in line245can be compressed to a pressure of about 20 bar to about 70 bar in compressor247. Higher pressures favor higher CO2recovery in the separated liquid CO2phase. The compressed gas then can be dried in a desiccant drier249, which can be thermally regenerated. For example, when an ASU is used as the oxidant source210, N2taken from the ASU in line219can be used for heating in the desiccant drier249. The dried, compressed gas then enters the CO2separation unit250. Carbon dioxide can exit the separation unit250in line251and preferably can have a purity level of at least 80%, at least 90%, at least 95%, or at least 99% molar CO2. Residual H2, along with the CO and CH4separated from H2in the hydrogen separation unit240can exit the CO2separation unit250through line253. This uncondensed gas, which is at elevated pressure, can be used as the supplementary fuel in the power cycle201. The syngas conditioning and cleanup in the cooling/conditioning unit230can, in some embodiments, involve partial removal of CO2in an acid gas removal step to obtain syngas that has a desired H2content prior to the H2recovery step. In such embodiment, CO2removal can be adjusted such that the cleaned syngas product in line239has an H2content of at least 60% and preferably at least 70% by volume. In such embodiments, the waste gas in line245exiting the H2separation unit240may be concentrated in CO2which would make it a preferred quality for low temperature CO2separation. In one or more embodiments, a carbon dioxide product stream (e.g., one or both of stream207and stream251) may be used as a feedstock for chemical production, such as urea synthesis, methanol synthesis, dimethyl ether (DME) synthesis, carbon-cured cement, and synthesis of further products. Beneficially, hydrogen required to generate further chemicals may be sourced from the first gas stream in line243exiting the hydrogen separation unit240(i.e., the stream of predominately hydrogen gas). For example, hydrogen from line243and nitrogen from line219(or otherwise sources) may be input to an ammonia synthesis unit260to create ammonia (in line261). Similarly, ammonia formed in this manner (or otherwise source ammonia) can be combined with substantially pure carbon dioxide (e.g., from stream207and/or stream251) to create urea. The nitrogen stream in line219can be taken from the ASU and pressurized according to the requirement of the ammonia process, typically to a pressure of about 100 bar or greater. This may be a pressure as taken from the ASU or, in some embodiments, a separate compressor may be provided in-line with line219(see compressor219a). Ammonia production reactions are highly exothermic and consequently a significant amount of heat (e.g., in the range of about 400° C. to about 600° C.) is typically generated in ammonia production processes. This heat can be recovered using a heat transfer fluid such as supercritical carbon dioxide and/or water and utilized as supplemental heating in the power production cycle to enhance the efficiency of power generation. This is shown by line262, which can be input to the power cycle201. The presently disclosed systems and methods can allow for substantial elimination or complete elimination of dedicated nitrogen, sulfur, and/or carbon handling systems during the processing of raw syngas for hydrogen production. Furthermore, the presently disclosed systems and methods can provide a desirable level of thermodynamic efficiency that can be comparable to or greater than that of current processes while simultaneously reducing system complexity. This can be achieved, at least in part, due to the ability to use low quality sensible heat in the co-operated power cycle201(e.g., power cycle100inFIG.1). For example, U.S. Pat. No. 8,596,075, the disclosure of which is incorporated herein by reference, describes methods for low grade heat integration to improve efficiency of a power production cycle, and such low grade heat integration can likewise be incorporated into the power production cycle utilized according to the present disclosure. This can substantially or completely eliminate the need for additional hydrogen production through water gas shift (WGS) reactions in order to maintain production/feedstock utilization efficiency. Through the elimination of such further equipment requirements (e.g., for carrying out WGS reactions, methanation units, and the like), the parasitic energy consumption associated with hydrogen production can be reduced over that of traditional processes. In addition, the integration of hydrogen production with the power production cycle can also enables carbon dioxide capture and compression without the addition of equipment beyond the existing requirements of the power cycle. Moreover, unlike polygeneration concepts where power must be produced using hydrogen or clean syngas, the fuel provided to the power production cycle according to the present disclosure can be include a significant concentration of carbon monoxide while also being hydrogen-depleted, thereby allowing for the greatest preservation of the feedstock's hydrogen content with minimal upstream processing. The presently disclosed systems and methods can be particularly beneficial in that carbon capture units that are required in known systems (and are typically significantly expensive) can be completely eliminated. Likewise, full conversion of water-gas-shift reactors is not required according to the present disclosure. Even further, high pressure steam generation equipment can be eliminated since low-grade, sensible heat can be used for improved energy efficiency, as noted above, and complicated cooling/refrigeration trains needed for methanation and carbon dioxide capture solvents can also be eliminated. In comparison to known systems, the present disclosure can provide systems and methods that are cost effective, highly efficient, and effective for substantial or complete carbon capture with co-power generation. Thus, the present disclosure provides an easily implementable poly-generation system and method that has not heretofore been achievable according to the prior art. In light of the foregoing, the present disclosure can provide a variety of configurations wherein cogeneration of power and at least hydrogen can be provided. In such embodiments, a hot syngas stream225can be provided from the syngas generation unit220, which can operate via, for example, coal gasification and/or natural gas partial oxidation, and/or natural gas reforming. The hot syngas stream225can be at least partially cooled in unit230, such as by using a heat transfer fluid. In preferred embodiments, the heat transfer fluid can be a carbon dioxide stream and/or a water stream that is utilized in the power cycle201. The heat transfer fluid particularly can comprise at least supercritical carbon dioxide. Utilization of the carbon dioxide stream (or other stream) from the power production cycle to cool the syngas stream can be particularly useful to enhance the efficiency of the power generation process. For example, heat transferred from the syngas stream225to the carbon dioxide stream (e.g., the stream in line234) can be used for low grade heating of the recycle carbon dioxide stream in the power cycle to improve the cycle efficiency as previously discussed. The final cooled gas temperature is determined according to the inlet temperature of a Water-Gas Shift (WGS) step that can be carried out in the syngas generation unit220. The WGS step can be beneficial to react carbon monoxide with steam and generate added hydrogen and carbon dioxide to the system. Shifting can be performed on a slipstream of syngas and not the total syngas stream in order to reduce the cost of shift process and associated equipment. In such as case, the shift step can be designed such that the hydrogen concentration in the recombined total syngas stream can be enough for economic downstream separation. This can be achieved by controlling one or more of the steam fed into the shift reactor, the size of the catalyst bed, and flow rate of the slipstream to the shift reactors. Pressure swing absorber hydrogen recovery beds typically requires at least 60% molar hydrogen in the feed stream to achieve economic hydrogen recovery (e.g., at least 80% molar hydrogen recovery). When hydrogen sulfide is present in the high temperature syngas stream (e.g., when the syngas is provided from a partial oxidation step), a sour WGS step followed by a downstream acid gas removal for hydrogen sulfide separation is typically utilized. In sour WGS, sulfur resistant shift catalysts, such as cobalt-molybdenum based compositions, can be used. Shifted syngas potentially cleaned from sulfur contaminants can then be fed into a hydrogen separation and recovery unit. When cogeneration of power and hydrogen is desired, as discussed above, the tail gas (see line245inFIG.2or line253inFIG.3) from the hydrogen separation unit240can be used as a fuel gas for power generation in a supercritical carbon dioxide power cycle such as described herein. The tail gas from a PSA hydrogen recovery unit typically can be at a pressure of about 1 to 2 bar and can contain hydrogen, carbon oxides, and methane. The tail gas can be pressurized (see compressor247, which optionally may be present in line245inFIG.2as well) and sent to power production plant as fuel gas. Excessive shifting of the syngas prior to hydrogen recovery can reduce the heating value of the tail gas from the hydrogen separation unit240, which will consequently reduce the amount of power that can be generated. The WGS reaction is exothermic and thus the syngas stream temperature will rise along the length of the shift reactor. The heat from shifted syngas can be recovered using a heat transfer fluid such as supercritical carbon dioxide or water and utilized in a supercritical carbon dioxide power cycle to enhance the efficiency of power generation. After heat recovery from shifted syngas and further cooling, a total syngas stream can be optionally directed to an acid gas removal unit to selectively remove hydrogen sulfide. In further embodiments, in addition to generation of power, hydrogen, and ammonia, the presently disclosed systems and methods can further be useful in production of urea. As such, a urea synthesis unit can be included downstream of the ammonia production train. This is shown in the embodiment illustrated inFIG.4; however, it is understood that the urea synthesis unit may likewise be incorporated in the embodiments illustrated inFIG.3. Referring toFIG.4, fuel in line421is passed to the syngas generation unit420, which may be configured as otherwise described above. Moreover, one or more further feed streams (e.g., a steam stream) may be input to the syngas generation unit420as desired. Raw syngas exits the syngas generation unit in line425and is passed to the hydrogen separation unit440. If needed, a cooling and/or conditioning unit (see unit230above) may be provided between the syngas generation unit420and the hydrogen separation unit440to achieve the desired conditions of the raw syngas entering the hydrogen separation unit. A fuel gas exiting the hydrogen separation unit440through line445can be passed to a power cycle combustor/turbine while a stream of predominately hydrogen exits the hydrogen separation unit440in line443. The fuel gas in line443is a hydrogen-depleted stream of one or more fuel gases and preferably can include a significant content of CO. Oxidant in line411is passed from the oxidant source410into the combustor/turbine unit490. Likewise, oxidant in line412is passed from the oxidant source410to the syngas generation unit420. As noted previously, the oxidant source410may be an ASU or other suitable unit configured for providing oxygen in lines411/412and nitrogen in line419, which is further discussed below. If needed, a further fuel source may be used to supplement the fuel gas in line445and/or may be passed directly to the combustor/turbine490. The power cycle components illustrated inFIG.4may be supplemented as desired to include one or more elements already described above and illustrated inFIG.1. The power cycle combustor/turbine490may be a single, combined unit that is configured for both combustion and expansion of the combustor exhaust, or a separate combustor and turbine may be utilized. Expanded exhaust in line491exits the combustor/turbine and is passed to the power cycle heat exchanger495to be cooled and provide a cooled exhaust stream in line496. The cooled exhaust is treated in the DeSNOx unit470to remove sulfur compounds primarily and optionally any nitrogen compounds present in the exhaust stream. Sulfur and/or nitrogen compounds exit the unit470through line471for disposal or other uses, and a substantially pure stream of CO2(e.g., at least 80%, at least 90%, at least 95%, or at least 99% molar CO2) exits in line472. All or part of the CO2in line472may be recycled back to the power cycle combustor/turbine through line476. As illustrated, all or part of the CO2in line472may be passed in line476athrough the power cycle heat exchanger495for re-heating prior to passage in line476bto the combustor/turbine490. The CO2in line472may be compressed in compressor472aprior to passage back to the combustor/turbine. Hydrogen in line443and nitrogen in line419can be combined in the ammonia synthesis unit460to provide a stream of ammonia in line461as previously discussed above. Part of all of the ammonia in line461may be passed to the urea synthesis unit480to produce a stream of urea in line481. The urea synthesis unit480can be fed with high pressure carbon dioxide from the power production cycle and along with the ammonia from the ammonia synthesis unit. The CO2for urea synthesis is provided in line474and can be taken at the same or different pressure as the CO2that is recycled to the combustor/turbine unit490through line476. Steam may be input to the urea synthesis unit through line482. The steam may come from any suitable source, including an outside source. Moreover, in embodiments wherein steam may be formed in the power cycle, steam can be withdrawn from the power cycle for use in the urea synthesis unit. As illustrated inFIG.4, steam may be taken from the syngas generation unit in line426, and all or part of the steam in line426may be input through line482into the urea synthesis unit480. Likewise, all or part of the steam in line426may be input to the ammonia synthesis unit460through line462. As such, steam may be output from the ammonia synthesis unit460through line463, and all or part of the steam in line463may be passed through line482into the urea synthesis unit480through line482. As can be seen from the foregoing, the present disclosure can provide a facility that adapts a power production cycle (e.g., utilizing a fuel source that is hydrogen-depleted) for the co-production of a hydrogen export stream, which eliminates the typical gas processing equipment required for such hydrogen production, leading to significant cost savings while simultaneously generating power and capturing carbon dioxide normally emitted by this process. In some embodiments, such facility can be configured so that the part or all of the hydrogen export stream may also be used in conjunction with part or all of a carbon dioxide export stream from a power production cycle to produce additional value-added products, such as urea. Examples Co-Production of Urea and Power With reference again toFIG.4, co-production of urea and power may be achieved, in some embodiments, utilizing more specific process and system conditions. In particular, a feedstock (line421) is sent to a gasifier or a SMR unit (420) to create raw syngas (line425). Hydrogen is separated from raw syngas using a pressure swing absorption (PSA) separation unit (440) to provide hydrogen (line443) for Ammonia synthesis. CO-rich syngas (line445) is sent to a power cycle combustor and turbine (490) for power generation. Turbine exhaust (containing predominately carbon dioxide) is directed through line491into the power cycle heat exchanger (495) for high grade heat recuperation. A carbon dioxide stream (line496) exiting the heat exchanger is then directed to a water separator (DeSNOx unit470) for water removal. In the water removal column, any SOx and NOx from the combustion flue gas can be removed in the forms of H2SO4and HNO3(line471). Sulfur species from coal used in the syngas production can be removed from the syngas via conventional acid gas removal processes. Carbon dioxide exiting the water separator unit in line472can be at ambient temperature and a pressure of about 30 bar, and the carbon dioxide can be substantially free of liquid water and SOx/NOx. A portion (e.g., about 60% to about 95%, about 75% to about 95%, or about 80% to about 90% by weight) of this carbon dioxide stream can be sent back to the power production cycle combustor/turbine through line476(preferably passing through the heat exchanger495for heat recovery via lines476aand476b). The remaining portion of the carbon dioxide can be sent via line474to a urea synthesis unit. One or both of the CO2 streams in line474and476may be first compressed to the same or different pressures in compressor472a, which may be a multi-stage compressor with optional inter-stage cooling. Nitrogen in line419(e.g., from the power cycle ASU410) and hydrogen in line443from the membrane separator440are sent to an ammonia synthesis unit460. The operating condition of the ammonia synthesis unit460can be about 200-250 bar and about 400° C. to about 500° C. Therefore, both of the nitrogen and the hydrogen are preferably provided in a compressed and pre-heated condition. The heat source of the ammonia synthesis process can be derived from the turbine exhaust in unit490, an uncooled compressor (e.g., in the ASU410or the CO2compressor472a, or another heat source in the system. Ammonia produced in line461from the ammonia synthesis unit460can be sold as a chemical product or can be sent to a urea synthesis unit480along with substantially pure carbon dioxide from the power production cycle (line474). Co-Production of Hydrogen and Power A feedstock is sent to a gasifier or a SMR unit (e.g., unit420) to create raw syngas (line425). Hydrogen is separated from raw syngas using a PSA separation unit (440) for synthesis of one or more chemicals, such as ammonia and urea (see the example above) or refinery operations, such as hydrotreating. Hydrogen-depleted syngas (line445) is sent to a power cycle combustor and turbine (490) for power generation. Turbine exhaust (containing predominately carbon dioxide) is directed through line491into the power cycle heat exchanger (495) for high grade heat recuperation. A carbon dioxide stream exiting the heat exchanger is then directed through line496to a water separator for water removal (which can be the DeSNOx unit470or a simple water separation unit (see element130inFIG.1). Sulfur species from coal used in the syngas production can be removed from the syngas via conventional acid gas removal processes, and such processes may be units included in syngas generation unit420. Carbon dioxide exiting the water separator unit (line472) can be at ambient temperature and a pressure of about 30 bar, and the carbon dioxide can be substantially free of liquid water and SOx/NOx. All or a portion of this carbon dioxide stream can be sent back to the power production cycle combustor/turbine as otherwise described above. The produced hydrogen can be used for the synthesis of other chemicals, such as ammonia, or can be directly fed into other processes, such as hydrotreating of hydrocarbons. Any remaining portion of the carbon dioxide can be directed through optional line474ato permanent underground sequestration or sent to a hydrocarbon synthesis unit485where H2from renewables and CO2-free sources can be provided to generate additional hydrocarbon products. H2in line444can be passed to the hydrocarbon synthesis unit485from one or more outside sources. Such hydrogen source preferably comes from a source that is renewable and that has low or no associated carbon dioxide emission. CO2for use in the hydrocarbon synthesis unit485may be taken in line474afrom the power cycle (or from another CO2-containing stream in the power cycle) and/or may be taken from line251exiting the CO2separation unit250. CO2and H2are reacted in the synthesis reactor485at a temperature of about 200° C. to about 400° C. or about 250° C. to about 350° C. (e.g., around 300° C.) and a pressure of about 20 bar to about 40 bar or about 25 bar to about 35 bar (e.g., around 30 bar) in the presence of a composite catalyst. CO2from turbine exhaust can be cooled down to 300° C. and directly sent to the synthesis reactor through line474a, before or after compression. Since the synthesis is an exothermic reaction, the heat released from the process can be used to preheat the recycled CO2to increase the power cycle efficiency Many modifications and other embodiments of the presently disclosed subject matter will come to mind to one skilled in the art to which this subject matter pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the present disclosure is not to be limited to the specific embodiments described herein and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. | 45,619 |
11859518 | DETAILED DESCRIPTION Aspects of the example implementations, as disclosed herein, relate to systems, methods, materials, compositions, articles, and improvements for a thermal energy storage system for power generation for various industrial applications. I. Overall System Problems to be Solved The present disclosure is directed to effectively storing VRE as thermal energy in solid storage media. While systems such as Cowper stoves store high-temperature energy in solid media, such units are charged and discharged at similar rates, and are heated and cooled primarily by convection, by flowing heat transfer gases. Pressure differences caused by any combination of buoyancy-mediated draft (the “stack effect”) and induced or forced flow (i.e., flow caused by a fluid movement system which may include fans or blowers) moves the heat transfer fluids through the solid media. Approaches such as this use convection for charge and discharge, with the heat transfer fluid being heated externally to the storage media array. But applying this approach to VRE storage disadvantageously requires large surface area and is therefore costly, because such convective heat transfer systems must operate at the much higher rates associated with VRE charging than heat delivery. Thermal storage systems include various element heaters, storage media, enclosing structures, and heat transfer subsystems, all of which may be affected by temperatures of the storage system and by the rate of change of such temperatures. Excessive temperatures and/or excessive rate of change of temperature can induce failures due to various effects. Some of these effects include material softening, oxide spallation, metal recrystallization, oxidation, and thermal stress-induced cracking and failure. Rising temperatures within a thermal storage unit cause thermal expansion of the materials that are used for thermal energy storage. Nonuniformities in these temperatures can cause stress in solids. Such temperature nonuniformities may arise during both discharging periods (due to flowing heat transfer fluids that cool the storage media) and charging periods (due to the high heat transfer rate). In general, a heat flux at one surface causes nonuniform temperatures within the solid media; such temperature nonuniformity causes heat to flow by conduction to cooler zones, at a rate determined by the thermal conductivity of the material and the magnitude of the temperature nonuniformity. Temperature nonuniformities may also be caused by repeated heating and cooling of a thermal storage array that includes heating elements and channels through which the heat transfer fluid flows. These nonuniformities may be amplified in successive cycles of heating and cooling, which in turn causes localized areas of a storage system to become excessively hot or cool during operation. This phenomenon is known as “thermal runaway,” and can lead to early-life failure of thermal storage arrays. Nonuniformities in temperature may be exacerbated when individual heating elements fail, resulting in the zone of a storage unit having the failed heating elements being unheated, while another zone of the storage unit continues to have active heating elements and high temperatures. Finally, VRE storage systems must operate under an exacting set of standards. They should be able to fully charge during periods that the variable energy is available (e.g., during daylight hours in the case of solar energy, as defined by a solar diurnal cycle that begins with the time of sunrise and ends with the time of sunset; it is understood that the time of sunrise and sunset can vary depending on physical location in terms of latitude and longitude, geography in terms of terrain, date, and season). They need to consistently deliver energy, even though their input energy source is not always predictably available. This means that these systems must sometimes be able to deliver output energy during periods that are longer than the periods of input-energy availability. VRE storage systems need to be able to operate under these conditions daily over decades of use. Overview of Solution The present disclosure relates to the field of thermal energy storage and utilization systems, and addresses the above-noted problems. A thermal energy storage system is disclosed that stores electrical energy in the form of thermal energy in a charging mode, and delivers the stored energy in a discharging mode. The discharging can occur at the same time as charging; i.e., the system may be heated by electrical energy at the same time that it is providing a flow of convectively heated air. The discharged energy is in the form of hot air, hot fluids in general, steam, heated CO2, heated supercritical CO2, and/or electrical power generation, and can be supplied to various applications, including industrial uses. The disclosed implementations include efficiently constructed, long-service-life thermal energy storage systems having materials, fabrication, physical shape, and other properties that mitigate damage and deterioration from repeated temperature cycling. Optionally, heating of the elements of the storage unit may be optimized, so as to store a maximum amount of heat during the charging cycle. Alternatively, heating of elements may be optimized to maximize heating element life, by means including minimizing time at particular heater temperatures, and/or by adjusting peak charging rates and/or peak heating element temperatures. Still other alternatives may balance these competing interests. Specific operations to achieve these optimizations are discussed further below. Example implementations employ efficient yet economical thermal insulation. Specifically, a dynamic insulation design may be used either by itself or in combination with static primary thermal insulation. The disclosed dynamic insulation techniques provide a controlled flow of air inside the system to restrict dissipation of thermal energy to the outside environment, which results in higher energy storage efficiency. System Overview FIG.1is a block diagram of a system1that includes a thermal energy storage system10, according to one implementation. In the implementation shown, thermal energy storage system10is coupled between an input energy source2and a downstream energy-consuming process22. For ease of reference, components on the input and output sides of system1may be described as being “upstream” and “downstream” relative to system10. In the depicted implementation, thermal energy storage system10is coupled to input energy source2, which may include one or more sources of electrical energy. Source2may be renewable, such as photovoltaic (PV) cell or solar, wind, geothermal, etc. Source2may also be another source, such as nuclear, natural gas, coal, biomass, or other. Source2may also include a combination of renewable and other sources. In this implementation, source2is provided to thermal energy storage system10via infrastructure4, which may include one or more electrical conductors, commutation equipment, etc. In some implementations, infrastructure4may include circuitry configured to transport electricity over long distances; alternatively, in implementations in which input energy source2is located in the immediate vicinity of thermal energy storage system10, infrastructure4may be greatly simplified. Ultimately, infrastructure4delivers energy to input5of thermal energy storage system10in the form of electricity. The electrical energy delivered by infrastructure4is input to thermal storage structure12within system10through switchgear, protective apparatus and active switches controlled by control system15. Thermal storage structure12includes thermal storage14, which in turn includes one more assemblages (e.g.,14A,14B) of solid storage media (e.g.,13A,13B) configured to store thermal energy. These assemblages are variously referred to throughout this disclosure as “stacks,” “arrays,” and the like. These terms are intended to be generic and not connote any particular orientation in space, etc. In general, an array can include any material that is suitable for storing thermal energy and can be oriented in any given orientation (e.g., vertically, horizontally, etc.). Likewise, the solid storage media within the assemblages may variously be referred to as thermal storage blocks, bricks, etc. In implementations with multiple arrays, the arrays may be thermally isolated from one another and are separately controllable, meaning that they are capable of being charged or discharged independently from one another. This arrangement provides maximum flexibility, permitting multiple arrays to be charged at the same time, multiple arrays to be charged at different times or at different rates, one array to be discharged while the other array remains charged, etc. Thermal storage14is configured to receive electrical energy as an input. As will be explained in greater detail below, the received electrical energy may be provided to thermal storage14via resistive heating elements that are heated by electrical energy and emit heat, primarily as electromagnetic radiation in the infrared and visible spectrum. During a charging mode of thermal storage14, the electrical energy is released as heat from the resistive heating elements, transferred principally by radiation emitted both by the heating elements and by hotter solid storage media, and absorbed and stored in solid media within storage14. When an array within thermal storage14is in a discharging mode, the heat is discharged from thermal storage structure12as output20. As will be described, output20may take various forms, including a fluid such as hot air. (References to the use of “air” and “gases” within the present disclosure may be understood to refer more generally to a “fluid.”) The hot air may be provided directly to a downstream energy consuming process22(e.g., an industrial application), or it may be passed through a steam generator (not shown) to generate steam for process22. More detail regarding steam generation is provided later in this Section, and more detail regarding various potential downstream processes is provided in Section IV. Additionally, thermal energy storage system10includes a control system15. Control system15, in various implementations, is configured to control thermal storage14, including through setting operational parameters (e.g., discharge rate), controlling fluid flows, controlling the actuation of electromechanical or semiconductor electrical switching devices, etc. The interface16between control system15and thermal storage structure12(and, in particular thermal storage14) is indicated inFIG.1. Control system15may be implemented as a combination of hardware and software in various embodiments. More detail regarding possible implementations of control system15is provided below with respect toFIGS.15through17. Control system15may also interface with various entities outside thermal energy storage system10. For example, control system15may communicate with input energy source2via an input communication interface17B. For example, interface17B may allow control system15to receive information relating to energy generation conditions at input energy source2. In the implementation in which input energy source2is a photovoltaic array, this information may include, for example, current weather conditions at the site of source2, as well as other information available to any upstream control systems, sensors, etc. Interface17B may also be used to send information to components or equipment associated with source2. Similarly, control system15may communicate with infrastructure4via an infrastructure communication interface17A. In a manner similar to that explained above, interface17A may be used to provide infrastructure information to control system15, such as current or forecast VRE availability, grid demand, infrastructure conditions, maintenance, emergency information, etc. Conversely, communication interface17A may also be used by control system15to send information to components or equipment within infrastructure4. For example, the information may include control signals transmitted from the control system15, that controls valves or other structures in the thermal storage structure12to move between an open position and a closed position, or to control electrical or electronic switches connected to heaters in the thermal storage14. Control system15uses information from communication interface17A in determining control actions, and control actions may adjust closing or firing of switches in a manner to optimize the use of currently available electric power and maintain the voltage and current flows within infrastructure4within chosen limits. Control system15may also communicate downstream using interfaces18A and/or18B. Interface18A may be used to communicate information to any output transmission structure (e.g., a steam transmission line), while interface18B may be used to communicate with downstream process22. For example, information provided over interfaces18A and18B may include temperature, industrial application demand, current or future expected conditions of the output or industrial applications, etc. As will be explained in greater detail below, control system15may control the input, heat storage, and output of thermal storage structure based on a variety of information. As with interfaces17A and17B, communication over interfaces18A and18B may be bidirectional—for example, system10may indicate available capacity to downstream process22. Still further, control system15may also communicate with any other relevant data sources (indicated by reference numeral21inFIG.1) via additional communication interface19. Additional data sources21are broadly intended to encompass any other data source not maintained by either the upstream or downstream sites. For example, sources21might include third-party forecast information, data stored in a cloud data system, etc. As will be described in detail below, thermal energy storage system10is configured to efficiently store thermal energy generated from input energy source2, and deliver output energy in various forms to a downstream process22. In various implementations, input energy source2may be from renewable energy and downstream process22may be an industrial application that requires an input such as steam or hot air. Through various techniques, including arrays of thermal storage blocks that use radiant heat transfer to efficiently storage energy and a lead-lag discharge paradigm that leads to desirable thermal properties such as the reduction of temperature nonuniformities within thermal storage14, system10may advantageously provide a continuous (or near-continuous) flow of output energy based on an intermittently available source. The use of such a system has the potential to reduce the reliance of industrial applications on fossil fuels. FIG.2provides a schematic view of one implementation of a system200for storing thermal energy, and further illustrates components and concepts just described with respect toFIG.1. As shown, one or more energy sources201provide input electricity. For example, and as noted above, renewable sources such as wind energy from wind turbines201a, solar energy from photovoltaic cells201b, or other energy sources may provide electricity that is variable in availability or price because the conditions for generating the electricity are varied. For example, in the case of wind turbine201a, the strength, duration and variance of the wind, as well as other weather conditions causes the amount of energy that is produced to vary over time. Similarly, the amount of energy generated by photovoltaic cells201balso varies over time, depending on factors such as time of day, length of day due to the time of year, level of cloud cover due to weather conditions, temperature, other ambient conditions, etc. Further, the input electricity may be received from the existing power grid201c, which may in turn vary based on factors such as pricing, customer demand, maintenance, and emergency requirements. The electricity generated by source201is provided to the thermal storage structure within the thermal energy storage system. InFIG.2, the passage of electricity into the thermal storage structure is represented by wall203. (More details as to the thermal storage structure are provided below with respect toFIGS.7through12.) The input electrical energy is converted to heat within thermal storage205via resistive heating elements207controlled by switches (not shown). Heating elements207provide heat to solid storage media209. As will be explained in greater detail in Section II, thermal storage components (sometimes called “bricks”) within thermal storage205are arranged to form embedded radiative chambers.FIG.2illustrates that multiple thermal storage arrays209may be present within system200. These arrays may be thermally isolated from one another and may be separately controllable.FIG.2is merely intended to provide a conceptual representation of how thermal storage205might be implemented—one such implementation might, for example, include only two arrays, or might include six arrays, or ten arrays, or more. In the depicted implementation, a blower213drives air or other fluid to thermal storage205such that the air is eventually received at a lower portion of each of the arrays209. The air flows upward through the channels and chambers formed by bricks in each of the arrays209, with flow controlled by louvers (as shown1611inFIG.18). By the release of heat energy from the resistive heating elements207, heat is radiatively transferred to arrays209of bricks during a charging mode. Relatively hotter brick surfaces reradiate absorbed energy (which may be referred to as a radiative “echo”), and participate in heating cooler surfaces. During a discharging mode, the heat stored in arrays209is output, as indicated at215. Once the heat has been output in the form of a fluid such as hot air, the fluid may be provided for one or more downstream applications. For example, hot air may be used directly in an industrial process that is configured to receive the hot air, as shown at217. Further, hot air may be provided as a stream219to a heat exchanger218of a steam generator222, and thereby heats a pressurized fluid such as air, water, CO2or other gas. In the example shown, as the hot air stream219passes over a line221that provides the water from the pump223as an input, the water is heated and steam is generated as an output225, which may be provided to an industrial application as shown at227. FIG.3provides a schematic view of a distributed control system300that highlights certain control aspects that may be present in particular implementations of the teachings of the present disclosure. As has been previously described, energy inputs to system300may include VRE sources (such as photovoltaic cells310and/or wind turbines320), as well as other sources340. Control system300, which may be referred to as a “smart energy controller,” is configured to exchange information with a variety of components within system300, including thermal energy storage control system399(also referred to as control system399for convenience) to automatically manage the operation of charging, discharging, and maintaining thermal energy storage in an intelligent manner. Control system399may include a variety of sensors/devices, including one or more voltage and current sensors integrated with power conditioning equipment311and switching equipment303, a wind sensor301, a sky camera302that detects passing clouds, and/or solar radiation sensor303. Control system399may also receive data via a network connection from various remote data sources, such as cloud data source304. Accordingly, control system399may access many different forms of information, including, for example, weather forecasts and market conditions such as the availability of electricity, cost of electricity, presence of other energy sources, etc. Control system399is also configured to communicate with input energy sources via power conversion and control devices such as303,311,321, and341. These controllers may be configured not only to pass data to control system399, but also to receive commands from control system399. Control system399may be configured in some instances to switch between input power sources in some instances by communicating with these controllers. Accordingly, in one implementation, control system399might analyze numerous different external data sources to determine which of several available input energy sources should be utilized, and then communicate with controllers such as311and321to select an input source. In a similar fashion, control system399may also communicate with downstream devices or systems, such as a steam generator334, a hot air output335, and an industrial application336. Control system399may use information from such input sensors to determine actions such as selectively activating switches303-1through303-N, controlling heaters within array330. Such control actions may include rapid-sequence activation of switches303-1through303-N in patterns to present varying total resistive loads in response to varying available power, so as to manage voltage and current levels at controllers311,321, and341within predetermined ranges. Information within the thermal storage structure itself may also be used by control system399. For example, a variety of sensors and communication devices may be positioned within the bricks, arrays, storage units and other locations within the thermal storage structure, as represented as electrical switches, including semiconductor switches, by303-1through303-N. The information may include state of charge, temperature, valve position, and numerous other operating parameters, and the switches may control the operation of the thermal storage system330, based on a signal received from the control system399, for example. Such control actions may include activation of switches303-1through303-N so as to manage temperatures and state of charge within array within predetermined ranges. Control system399can communicate with devices such as303to perform operations based on received data that may be either internal and/or external to the thermal storage structure. For example, control system399may provide commands to heating elements controls, power supply units, discharge blowers pumps, and other components to perform operations such as charging and discharging. Control system399may specifically receive data from thermal storage system330, including from subsections such as350, and individual bricks or heating elements such as305-1through305-N. The ability to receive data from numerous locations inside and outside the thermal storage structure permits system300to be able to operate in a flexible and efficient manner, which is advantageous given the challenges that arise from attempting to deliver a continuous supply of output energy from a variable source. A thermal storage structure such as that depicted inFIGS.1-3may also include output equipment configured to produce steam for use in a downstream application.FIG.4, for example, depicts a block diagram of an implementation of a thermal storage structure400that includes a storage-fired once-through steam generator (OTSG). An OTSG is a type of heat recovery stream generator (HRSG), which is a heat exchanger that accepts hot air from a storage unit, returns cooler air, and heats an external process fluid. The depicted OTSG is configured to use thermal energy stored in structure400to generate steam at output411. As has been described, thermal storage structure400includes outer structure401such walls, a roof, as well as thermal storage403in a first section of the structure. The OTSG is located in a second section of the structure, which is separated from the first section by thermal barrier425. During a charging mode, thermal energy is stored in thermal storage403. During a discharging mode, the thermal energy stored in thermal storage403receives a fluid flow (e.g., air) by way of a blower405. These fluid flows may be generated from fluid entering structure400via an inlet valve419, and include a first fluid flow412A (which may be directed to a first stack within thermal storage403) and a second fluid flow412B (which may be directed to a second stack within thermal storage403). As the air or other fluid directed by blower405flows through the thermal storage403from the lower portion to the upper portion, it is heated and is eventually output at the upper portion of thermal storage403. The heated air, which may be mixed at some times with a bypass fluid flow412C that has not passed through thermal storage402, is passed over a conduit409through which flows water or another fluid pumped by the water pump407. In one implementation, the conduit forms a long path with multiple turns, as discussed further in connection withFIG.5below. As the hot air heats up the water in the conduit, steam is generated at411. The cooled air that has crossed the conduit (and transferred heat to the water flowing through it) is then fed back into the brick heat storage403by blower405. As explained below, the control system can be configured to control attributes of the steam, including steam quality, or fraction of the steam in the vapor phase, and flow rate. As shown inFIG.4, an OTSG does not include a recirculating drum boiler. Properties of steam produced by an OTSG are generally more difficult to control than those of steam produced by a more traditional HRSG with a drum, or reservoir. The steam drum in such an HRSG acts as a phase separator for the steam being produced in one or more heated tubes recirculating the water; water collects at the bottom of the reservoir while the steam rises to the top. Saturated steam (having a steam quality of 100%) can be collected from the top of the drum and can be run through an additional heated tube structure to superheat it and further assure high steam quality. Drum-type HRSGs are widely used for power plants and other applications in which the water circulating through the steam generator is highly purified and stays clean in a closed system. For applications in which the water has significant mineral content, however, mineral deposits form in the drum and tubes and tend to clog the system, making a recirculating drum design infeasible. For applications using water with a higher mineral content, an OTSG may be a better option. One such application is oil extraction, in which feed water for a steam generator may be reclaimed from a water/oil mixture produced by a well. Even after filtering and softening, such water may have condensed solid concentrations on the order of 10,000 ppm or higher. The lack of recirculation in an OTSG enables operation in a mode to reduce mineral deposit formation; however, an OTSG needs to be operated carefully in some implementations to avoid mineral deposits in the OTSG water conduit. For example, having some fraction of water droplets present in the steam as it travels through the OTSG conduit may be required to prevent mineral deposits by retaining the minerals in solution in the water droplets. This consideration suggests that the steam quality (vapor fraction) of steam within the conduit must be maintained below a specified level. On the other hand, a high steam quality at the output of the OTSG may be important for the process employing the steam. Therefore, it is advantageous for a steam generator powered by VRE through TES to maintain close tolerances on outlet steam quality. There is a sensitive interplay among variables such as input water temperature, input water flow rate and heat input, which must be managed to achieve a specified steam quality of output steam while avoiding damage to the OTSG. Implementations of the thermal energy storage system disclosed herein provide a controlled and specified source of heat to an OTSG. The controlled temperature and flow rate available from the thermal energy storage system allows effective feed-forward and feedback control of the steam quality of the OTSG output. In one implementation, feed-forward control includes using a target steam delivery rate and steam quality value, along with measured water temperature at the input to the water conduit of the OTSG, to determine a heat delivery rate required by the thermal energy storage system for achieving the target values. In this implementation, the control system can provide a control signal to command the thermal storage structure to deliver the flowing gas across the OTSG at the determined rate. In one implementation, a thermal energy storage system integrated with an OTSG includes instrumentation for measurement of the input water temperature to the OTSG. In one implementation, feedback control includes measuring a steam quality value for the steam produced at the outlet of the OTSG, and a controller using that value to adjust the operation of the system to return the steam quality to a desired value. Obtaining the outlet steam quality value may include separating the steam into its liquid and vapor phases and independently monitoring the heat of the phases to determine the vapor phase fraction. Alternatively, obtaining the outlet steam quality value may include measuring the pressure and velocity of the outlet steam flow and the pressure and velocity of the inlet water flow, and using the relationship between values to calculate an approximation of the steam quality. Based on the steam quality value, a flow rate of the outlet fluid delivered by the thermal storage to the OTSG may be adjusted to achieve or maintain the target steam quality. In one implementation, the flow rate of the outlet fluid is adjusted by providing a feedback signal to a controllable element of the thermal storage system. The controllable element may be an element used in moving fluid through the storage medium, such as a blower or other fluid moving device, a louver, or a valve. The steam quality measurement of the outlet taken in real time may be used as feedback by the control system to determine the desired rate of heat delivery to the OTSG. To accomplish this, an implementation of a thermal energy storage system integrated with an OTSG may include instruments to measure inlet water velocity and outlet steam flow velocity, and, optionally, a separator along with instruments for providing separate measurements of the liquid and vapor heat values. In some implementations, the tubing in an OTSG is arranged such that the tubing closest to the water inlet is positioned in the lowest temperature portion of the airflow, and that the tubing closest to the steam exit is positioned in the highest temperature portion of the airflow. In some implementations of the present innovations, the OTSG may instead be configured such that the highest steam quality tubes (closest to the steam outlet) are positioned at some point midway through the tubing arrangement, so as to enable higher inlet fluid temperatures from the TSU to the OTSG while mitigating scale formation within the tubes and overheating of the tubes, while maintaining proper steam quality. The specified flow parameters of the heated fluid produced by thermal energy storage systems as disclosed herein may in some implementations allow precise modeling of heat transfer as a function of position along the conduit. Such modeling may allow specific design of conduit geometries to achieve a specified steam quality profile along the conduit. FIG.5illustrates a cross-section of the piping of an OTSG490. Continuous serpentine piping495is provided having multiple bends, and turnarounds at the end of each piping row. As shown, the flow within the pipe495passes through the OTSG and turns around, laterally across a row, and then moves upward one row at a time. The pipe495has a smaller diameter near the inlet and a larger diameter in the sections nearer the outlet. The increase in diameter is to enable adequate linear flow velocity of the cooler inlet fluid, which is smaller in volume and higher in viscosity, to enable effective heat transfer, and compensate for the expansion of steam without excessive flow velocities in the later tubing sections. In one implementation, the diameter is changed in a discrete manner, and in another the diameter of the piping may taper from a smaller diameter at the input to larger diameter at the output, or some combination of these two designs, such as a smaller-diameter tapered portion coupled to a larger, fixed-diameter portion of the pipe495. Openable ports may be provided at the inlet and the outlet of the serpentine tubing to enable the effective introduction, passage and removal of cleaning tools, or “pigs,” periodically driven through the piping to remove any internal deposits. It is beneficial for such cleaning or “pigging” for a tubing section being pigged to be of approximately constant inner diameter. Accordingly, openable ports may be positioned at the points where tubing diameter changes so as to enable the effective introduction and removal of pigs of sizes appropriate to each tubing diameter section during pigging operations. As shown inFIG.6, the output of the thermal energy storage system may be used for an integrated cogeneration system500. As previously explained, an energy source501provides electrical energy that is stored as heat in the heat storage503of the TSU. During discharge, the heated air is output at505. As shown inFIG.6, lines containing a fluid, in this case water, are pumped into a drum506of an HRSG509via a preheating section of tubing522. In this implementation, HRSG509is a recirculating drum type steam generator, including a drum or boiler506and a recirculating evaporator section508. The output steam passes through line507to a superheater coil, and is then provided to a turbine at515, which generates electricity at517. As an output, the remaining steam521may be expelled to be used as a heat source for a process, or condensed at519and optionally passed through to a deaeration unit513and delivered to pump511in order to perform subsequent steam generation. Certain industrial applications may be particularly well-suited for cogeneration. For example, some applications use higher temperature heat in a first system, such as to convert the heat to mechanical motion as in the case of a turbine, and lower-temperature heat discharged by the first system for a second purpose, in a cascading manner; or an inverse temperature cascade may be employed. One example involves a steam generator that makes high-pressure steam to drive a steam turbine that extracts energy from the steam, and low-pressure steam that is used in a process, such as an ethanol refinery, to drive distillation and electric power to run pumps. Still another example involves a thermal energy storage system in which hot gas is output to a turbine, and the heat of the turbine outlet gas is used to preheat inlet water to a boiler for processing heat in another steam generator (e.g., for use in an oilfield industrial application). In one application, cogeneration involves the use of hot gas at e.g. 840° C. to power or co-power hydrogen electrolysis, and the lower temperature output gas of the hydrogen electrolyzer, which may be at about 640° C., is delivered alone or in combination with higher-temperature heat from a TSU to a steam generator or a turbine for a second use. In another application, cogeneration involves the supply of heated gas at a first temperature e.g. 640° C. to enable the operation of a fuel cell, and the waste heat from the fuel cell which may be above 800° C. is delivered to a steam generator or a turbine for a second use, either alone or in combination with other heat supplied from a TSU. A cogeneration system may include a heat exchange apparatus that receives the discharged output of the thermal storage unit and generates steam. Alternately, the system may heat another fluid such as supercritical carbon dioxide by circulating high-temperature air from the system through a series of pipes carrying a fluid, such as water or CO2, (which transfers heat from the high-temperature air to the pipes and the fluid), and then recirculating the cooled air back as an input to the thermal storage structure. This heat exchange apparatus is an HRSG, and in one implementation is integrated into a section of the housing that is separated from the thermal storage. The HRSG may be physically contained within the thermal storage structure, or may be packaged in a separate structure with ducts conveying air to and from the HRSG. The HRSG can include a conduit at least partially disposed within the second section of the housing. In one implementation, the conduit can be made of thermally conductive material and be arranged so that fluid flows in a “once-through” configuration in a sequence of tubes, entering as lower-temperature fluid and exiting as higher temperature, possibly partially evaporated, two-phase flow. As noted above, once-through flow is beneficial, for example, in processing feedwater with substantial dissolved mineral contaminants to prevent accumulation and precipitation within the conduits. In an OTSG implementation, a first end of the conduit can be fluidically coupled to a water source. The system may provide for inflow of the fluids from the water source into a first end of the conduit, and enable outflow of the received fluid or steam from a second end of the conduit. The system can include one or more pumps configured to facilitate inflow and outflow of the fluid through the conduit. The system can include a set of valves configured to facilitate controlled outflow of steam from the second end of the conduit to a second location for one or more industrial applications or electrical power generation. As shown inFIG.6, an HRSG may also be organized as a recirculating drum-type boiler with an economizer and optional superheater, for the delivery of saturated or superheated steam. The output of the steam generator may be provided for one or more industrial uses. For example, steam may be provided to a turbine generator that outputs electricity for use as retail local power. The control system may receive information associated with local power demands, and determine the amount of steam to provide to the turbine, so that local power demands can be met. In some implementations, the “hybrid” or joint supply of steam or process heat from a thermal storage unit powered by VRE and a conventional furnace or boiler powered by fossil fuel is beneficial.FIG.97discloses a system9900where a fuel-fired heater9905(furnace, boiler, or HRSG) supplies heat in the form of a first flow of hot gas or steam to a use9909(e.g. A turbine, an oilfield, a factory), and a thermal storage unit9901powered by VRE or intermittent grid power provides heat in the form of a second flow of hot gas or steam to the use. The two sources—fuel-powered (9905) and VRE-powered (9907)—may be fluidically connected to a common supply inlet9907of air, CO2, salt, oil, or water to be heated, and fluidically connected to a common outlet or use of heated fluid or steam. A controller9903may control or partially control the operation of the fuel-fired heater9905and the VRE storage heater9901, with inputs to the controller including information derived from forecasts of weather9910, the pricing and availability of electricity9911, the pricing and availability of fuel9911, the state of charge of the TSU9915, the readiness and state of the equipment9913, and the current and planned energy requirements of the connected load9914. The controller may schedule and control the operation of TSU charging, fuel combustion, and TSU output in a means to meet the needs of the use at the lowest possible CO2emissions and/or the lowest total operating cost. In addition to the generation of electricity, the output of the thermal storage structure may be used for industrial applications as explained below. Some of these applications may include, but are not limited to, electrolyzers, fuel cells, gas generation units such as hydrogen, carbon capture, manufacture of materials such as cement, calcining applications, as well as others. More details of these industrial applications are provided further below. Thermal Storage Structure FIG.7illustrates an isometric view700of one implementation of a thermal storage structure701, which is an implementation of thermal storage structure12depicted inFIG.1. More specifically, structure701includes a roof703, sidewalls705, and a foundation707. As shown at709, a blower is provided that may draw air in and out for temperature regulation and safety. At711, a housing is shown that may house the blower, steam generation unit, and/or other equipment associated with an input or an output to structure701. Further, switchgear or other electrical and electronic equipment may be installed at thermal storage structure701. This is made possible due to the dynamic insulation, which reduces the heat that is transferred to the outer surface of structure701, which in turn allows for equipment having a limited temperature operating range to be positioned there. Such equipment may include sensors, telecommunication devices, controllers, or other equipment required to operate structure701. FIG.8illustrates a perspective view800of a thermal storage structure801. As shown above, the plenum near803and sidewalls805are shown. The inside of the roof includes insulation807. At809, the housing may contain the exhaust or blower as explained above. As shown at811, the passages between the stacks of structure801and the outer surface of the sidewalls805may be provided as a vertically slotted chamber. Such vertical slots are optional, however, and other configurations may be used, including a configuration that has no slots and forms a chamber. As explained above, the cool air is provided by the blower to a gap between the bricks and the insulation807, and subsequently flows down the walls of structure801to the plenum near803, where the cool air is warmed by heat from the stacks of bricks as it passes between the stacks of bricks and the insulation807, and out to a steam generator813, for example. The somewhat warmed air flows through air flow paths in the stacks of bricks, from below. Further, element809may also include the blower. Finally, the system may be an open-loop, as opposed to a closed-loop, configuration. This means, for example, that intake ambient air instead of recirculating air from the industrial application may be used. FIG.9illustrates a top view900of the inner roof of a thermal storage structure901according to an example implementation. As explained above, an insulating layer903surrounds the hot bricks, and provides a heat barrier between the output of the stacks of bricks and the outer structure of the thermal storage structure901. The incoming air, which may be driven by a blower (such as one in air exchange device905), flows through the sidewalls to the plenum at the base of foundation911. Also shown is the slotted portion907and the steam generator909, as explained above. As used in the present disclosure, “cool” air refers to air that is cooler than the discharge air when the TSU is charged, though it may be in fact quite warm, e.g. around 200° C. or more, in the case of return air from a process, or it may be cooler, ambient-temperature outdoor air in the case of air provided from the environment surrounding the thermal storage unit; or at some temperature between these ranges, depending upon the source of the “cool” air. FIG.10illustrates a bottom portion1000under the stack of bricks. Once the fluid arrives at the bottom of the thermal storage structure described above with respect toFIG.9, it flows from the edges1003lengthwise through channels to a region1001underneath the stack of bricks. This fluid, which is significantly cooler than the temperature of the top of the stack when the stack is charged, cools the foundation and the exterior and provides an insulative layer between the stack and the surrounding structure including the foundation, and thus reduces heat losses and allows the use of inexpensive, ordinary insulation materials. This prevents heat damage to the surrounding structure and foundation. FIG.11illustrates an isometric view1100of a thermal storage structure. As shown, a seismic reinforcing structure1101is provided on the outside of an outer surface of the entire structure. The structure1103, which may house an air exchange device or other equipment as explained above, is formed on top of the seismic reinforcing structure1101. As shown in1105, an insulated layer is formed above the stacks of bricks, leaving an air gap for dynamic insulation for the cool air. Sidewalls1107, foundation1109, slotted portion1113and steam generator1111are also included. Additionally, one or more base isolators1115(which may include elastic and/or plastic deformation materials which may act respectively as springs and as energy absorbers) may be provided below the foundation that reduce the peak forces experienced during seismic events. In some implementations, the base isolator may reduce the peak force in an earthquake such that 10% or less of the force from the earthquake is transferred to the structures above the base isolator. The above percentages may vary as a function of relative motion between the ground and base isolator. Just as an example, the thermal energy storage structure may include a space of 45 cm to 60 cm between the ground and the slab to reduce the g-forces transmitted to stack by 90%. By providing the seismic reinforcing structure1101, the thermal storage structure may be more safely operated in earthquake-prone regions. FIG.12illustrates an isometric view1200of a support structure for bricks in a thermal storage structure according to an example implementation. A foundation1201, shown as beams attached to one another, forms a base upon which stacks of bricks may be positioned. Structures1203a,1203bform a support for the bricks. A vertical support1207, which may directly interface with the bricks, and a support beam1205provide additional support. FIG.13illustrates views1300of additional structures that may be associated with a thermal storage structure. For example, a blower1301receives air and blows it into the structure. As explained above, the air may, in some cases, be cooled air that has passed through the steam generator. At1303, louvers are illustrated, which may control the inlet air flowing into the thermal storage elements. Such louvers may be positioned so as to selectively adjust the flow of air through regions of the TSU so as to adjust the discharge of high-temperature air while being positioned in flows of lower-temperature air. Such louvers may incorporate fail-safe controls that set the louvers to a pre-determined position upon the failure of a control system, an actuator, or a supply of electric power, by actuation means that may include springs, weights, compressed air, materials that change dimensions with temperature, and/or other means. Dynamic Insulation It is generally beneficial for a thermal storage structure to minimize its total energy losses via effective insulation, and to minimize its cost of insulation. Some insulation materials are tolerant of higher temperatures than others. Higher-temperature tolerant materials tend to be more costly. FIG.14provides a schematic section illustration1400of an implementation of dynamic insulation. Note that while the following discussion ofFIG.14provides an introduction to dynamic insulation techniques and passive cooling, more detailed examples are provided below with reference toFIGS.57through62. The outer container includes roof1401, walls1403,1407and a foundation1409. Within the outer container, a layer of insulation1411is provided between the outer container and columns of bricks in the stack1413, the columns being represented as1413a,1413b,1413c,1413dand1413e. The heated fluid that is discharged from the upper portion of the columns of bricks1413a,1413b,1413c,1413dand1413eexits by way of an output1415, which is connected to a duct1417. The duct1417provides the heated fluid as an input to a steam generator1419. Once the heated fluid has passed through the steam generator1419, some of its heat is transferred to the water in the steam generator and the stream of fluid is cooler than when exiting the steam generator. Cooler recycled fluid exits a bottom portion1421of the steam generator1419. An air blower1423receives the cooler fluid, and provides the cooler fluid, via a passage1425defined between the walls1403and insulation1427positioned adjacent the stack1413, through an upper air passage1429defined between the insulation1411and the roof1401, down through side passages1431defined on one or more sides of the stack1413and the insulation1411, and thence down to a passage1433directly below the stack1413. The air in the passages1425,1429,1431and1433acts as an insulating layer between (a) the insulations1411and1427surrounding the stack1413, and (b) the roof1401, walls1403,1407and foundation1409. Thus, heat from the stack1413is prevented from overheating the roof1401, walls1403,1407and foundation1409. At the same time, the air flowing through those passages1425,1429,1431and1433carries by convection heat that may penetrate the insulations1411and/or1417into air flow passages1435of the stack1413, thus preheating the air, which is then heated by passage through the air flow passages1435. The columns of bricks1413a,1413b,1413c,1413dand1413eand the air passages1435are shown schematically inFIG.14. The physical structure of the stacks and air flow passages therethrough in embodiments described herein is more complex, leading to advantages as described below. In some implementations, to reduce or minimize the total energy loss, the layer of insulation1411is a high-temperature primary insulation that surrounds the columns1413a,1413b,1413c,1413dand1413ewithin the housing. Outer layers of lower-cost insulation may also be provided. The primary insulation may be made of thermally insulating materials selected from any combination of refractory bricks, alumina fiber, ceramic fiber, and fiberglass or any other material that might be apparent to a person of ordinary skill in the art. The amount of insulation required to achieve low losses may be large, given the high temperature differences between the storage media and the environment. To reduce energy losses and insulation costs, conduits are arranged to direct returning, cooler fluid from the HRSG along the outside of a primary insulation layer before it flows into the storage core for reheating. The cooler plenum, including the passages1425,1429,1431and1433, is insulated from the outside environment, but total temperature differences between the cooler plenum and the outside environment are reduced, which in turn reduces thermal losses. This technique, known as “dynamic insulation,” uses the cooler returning fluid, as described above, to recapture heat which passes through the primary insulation, preheating the cooler air before it flows into the stacks of the storage unit. This approach further serves to maintain design temperatures within the foundation and supports of the thermal storage structure. Requirements for foundation cooling in existing designs (e.g., for molten salt) involve expensive dedicated blowers and generators—requirements avoided by implementations according to the present teaching. The materials of construction and the ground below the storage unit may not be able to tolerate high temperatures, and in the present system active cooling—aided by the unassisted flowing heat exchange fluid in the case of power failure—can maintain temperatures within design limits. A portion of the fluid returning from the HRSG may be directed through conduits such as element1421located within the supports and foundation elements, cooling them and delivering the captured heat back to the input of the storage unit stacks as preheated fluid. The dynamic insulation may be provided by arranging the bricks1413a,1413b,1413c,1413dand1413ewithin the housing so that the bricks1413a,1413b,1413c,1413dand1413eare not in contact with the outer surface1401,1403,1407of the housing, and are thus thermally isolated from the housing by the primary insulation formed by the layer of cool fluid. The bricks1413a,1413b,1413c,1413dand1413emay be positioned at an elevated height from the bottom of the housing, using a platform made of thermally insulating material. During unit operation, a controlled flow of relatively cool fluid is provided by the fluid blowing units1423, to a region (including passages1425,1429,1431and1433) between the housing and the primary insulation (which may be located on an interior or exterior of an inner enclosure for one or more thermal storage assemblages), to create the dynamic thermal insulation between the housing and the bricks, which restricts the dissipation of thermal energy being generated by the heating elements and/or stored by the bricks into the outside environment or the housing, and preheats the fluid. As a result, the controlled flow of cold fluid by the fluid blowing units of the system may facilitate controlled transfer of thermal energy from the bricks to the conduit, and also facilitates dynamic thermal insulation, thereby making the system efficient and economical. In another example implementation, the buoyancy of fluid can enable an unassisted flow of the cold fluid around the bricks between the housing and the primary insulator1411such that the cold fluid may provide dynamic insulation passively, even when the fluid blowing units1423fail to operate in case of power or mechanical failure, thereby maintaining the temperature of the system within predefined safety limits, to achieve intrinsic safety. The opening of vents, ports, or louvres (not shown) may establish passive buoyancy-driven flow to maintain such flow, including cooling for supports and foundation cooling, during such power outages or unit failures, without the need for active equipment. These features are described in greater detail below in connection withFIGS.58-62. In the above-described fluid flow, the fluid flows to an upper portion of the unit, down the walls and into the inlet of the stacking, depending on the overall surface area to volume ratio, which is in turn dependent on the overall unit size, the flow path of the dynamic insulation may be changed. For example, in the case of smaller units that have greater surface area as compared with the volume, the amount of fluid flowing through the stack relative to the area may utilize a flow pattern that includes a series of serpentine channels, such that the fluid flows on the outside, moves down the wall, up the wall, and down the wall again before flowing into the inlet. Other channelization patterns may also be used. Additionally, the pressure difference between the return fluid in the insulation layer and the fluid in the stacks may be maintained such that the dynamic insulation layer has a substantially higher pressure than the pressure in the stacks themselves. Thus, if there is a leak between the stacks and the insulation, the return fluid at the higher pressure may be forced into the leak or the cracks, rather than the fluid within the stacks leaking out into the dynamic insulation layer. Accordingly, in the event of a leak in the stacks, the very hot fluid of the stacks may not escape outside of the unit, but instead the return fluid may push into the stacks, until the pressure between the dynamic insulation layer in the stacks equalizes. Pressure sensors may be located on either side of the blower that provide relative and absolute pressure information. With such a configuration, a pressure drop within the system may be detected, which can be used to locate the leak. Earlier systems that store high temperature sensible heat in rocks and molten salts have required continuous active means of cooling foundations, and in some implementations continuous active means of heating system elements to prevent damage to the storage system; thus, continuous active power and backup power supply systems are required. A system as described herein does not require an external energy supply to maintain the safety of the unit. Instead, as described below, the present disclosure provides a thermal storage structure that provides for thermally induced flows that passively cools key elements when equipment, power, or water fails. This also reduces the need for fans or other cooling elements inside the thermal storage structure. Control System The operation of a thermal storage unit as described herein can be optimized based on factors such as the lifetime of the components (heaters, bricks, structure, electronics, fans, etc.), required temperature and duration of output heat, availability of energy source and cost, among other factors. In some instances, the components exposed to high temperature are limited, using dynamic insulation to reduce temperatures of foundation, walls, etc.). The control system may use feedback from computer models, weather predictions and sensors such as temperature and airflow to optimize long term performance. In particular, rates of heating and cooling as well as duration at peak temperature can have a detrimental effect on the lifetime of heating elements, bricks and other components. As physical properties of the components and airflow patterns, for example, may change as they age, feedback can be used to inform an artificial intelligence (AI) system to continue to provide high performance for years. Examples of such evolving physical properties and data reflecting such changes may include changing resistance of the heater elements, failure of heaters, changes in airflow behavior, and changes in heat transfer in bricks due to cracks or other damage. An operational mode that reduces exposure to peak temperature can use data from models, weather predictions, sensors and time of year and location information to intelligently tune charging rates and extent. For example, during peak photovoltaic (PV) production days of summer, the days are relatively long and dark hours are relatively short. If the weather prediction expects multiple sunny days in a row, the thermal storage unit does not need to be charged to a high degree in order for the storage to serve the customer's needs during dark hours. In such an example case, reducing the charging extent and peak temperature reduces the stress on the system so that service life is increased. Example implementations of the present disclosure may include a smart energy storage controller system300as described above with respect toFIG.3. The system300monitors and receives information associates with local parameters such as wind, solar radiation, and passing clouds. The system300can also be configured to receive any one or more of network-supplied hourly and multiday forecasts of weather, forecast and current availability and cost of VRE and/or other available energy sources, forecast and current energy demand of load. This includes information on industrial process requirements, current and forecast prices of energy, contractual or regulatory requirements to maintain a minimum state of charge to participate in capacity or resource adequacy transactions and markets. The system300further include state of charge and temperature of subsections of the storage media. FIG.15is a block diagram illustrating one implementation of various control systems that may be located throughout the system300. As shown, system1500includes several constituent control systems configured to control different portions of distributed control system300. These control systems include thermal storage control system1502, application control system1504, power source control system1506and external analysis system1508. Constituent control systems in system1500are interconnected using communication links such as1501,1503and1505. Links1501,1503and1505may be wired, wireless, or combinations thereof. Other implementations of a control system for thermal energy storage and distribution may include different combinations and types of constituent control systems. Thermal storage control system1502is configured to control a thermal energy storage system such as those that have been disclosed herein, and may be an implementation of control system15depicted inFIG.1. Elements controlled by system1502may include, without limitation, switches, valves, louvers, heating elements and blowers associated with thermal storage assemblages, including switches for connecting input energy from energy sources such as a solar field or wind farm. Control system1502is configured to receive information from various sensors and communication devices within the thermal energy storage system, providing information on parameters that may include state of thermal energy charge, temperature, valve or louver position, fluid flow rate, information about remaining lifetime of components, etc. Control system1502may then control system operation based on these parameters. In one implementation, control system1502may be configured to control aspects of the upstream energy source and/or the downstream application system. Power source control system1506is configured to control aspects of the energy source for the thermal storage system. In one implementation, the energy source is a source of variable renewable electricity such as a field of photovoltaic panels (“solar field”) or a wind turbine farm. Systems1502and1506are configured to communicate with one another to exchange control information and data, including data relating to the operational status of the thermal energy storage system or energy source, input energy requirements of the thermal energy storage system, predicted future output of the energy source, etc. In one implementation, control system1506may be configured to control one or more aspects of the thermal energy storage system relevant to operation of the energy source. Application control system1504is configured to control aspects of a system receiving output energy from the thermal energy storage system controlled by system1502. Systems1502and1504are configured to communicate with one another to exchange control information and data, including data relating to the operational status of the thermal energy storage system or application system, amount of energy output from the thermal storage system needed by the application system, predicted future energy output from the thermal storage system, etc. In one implementation, control system1504may be configured to control one or more aspects of the thermal energy storage system relevant to operation of the application system. External analytics system1508is configured, in one implementation, to obtain and analyze data relevant to operation of one or more of systems1502,1504and1506. In one implementation, system1508is configured to analyze forecast information such as weather information or energy market information and generate predictions regarding availability or cost of input power to thermal storage control system1502. System1508may then communicate with thermal storage control system1502over link1503in order to convey information and/or commands, which may then be implemented by system1502and/or systems1506and1504. FIG.16is a block diagram illustrating one implementation of thermal storage control system1502. As shown, system1502includes a processor1510, memory1512, data storage1514and communications interface1516. Processor1510is a processor configured to execute programs stored in memory1512, such as control programs1518for managing the operation of one or more thermal storage arrays similar to those described herein. InFIG.16, memory1512is shown as being located within processor1510, but in other implementations external memory or a combination of internal and external memory is possible. Control programs1518may include a variety of programs, including those for sending signals to various elements associated with a thermal storage structure, such as switches for heater elements, louvers, blowers, valves for directing and adjusting gas flows, etc. Execution of control programs1518can thus effectuate various modes of operation of the thermal storage system, including charging and discharging, as well as coordinated operation of multiple thermal storage arrays to maintain a specified temperature profile (e.g., a constant temperature or a non-constant predefined temperature schedule). Two potential types of control are sensor-based control and model-based control. In a sensor-based control paradigm, readings from sensors placed throughout system1500may be used to determine real-time values that correspond to actual measurements. Thermal storage structures according to this disclosure may be designed in order to limit the exposure of certain components to high, thereby improving reliability. But the use of sensors, while potentially representing the most accurate possible state of system1500, may be expensive, and also may be prone to malfunction if sensors fail. A model-based control paradigm, on the other hand, provides the ability to control a large complex system with less expense than that associated with deploying a multitude of sensors, and to minimize safety risks that might be associated with undetected sensor failure. A modeling program1520within memory1512may thus be used to model and predict behavior of the thermal energy storage system over a range of input parameters and operational modes. Control system1502may also be configured to combine model-based and sensor-based control of the thermal energy storage system—which may allow for redundancy as well as flexibility in operation. Other programs may also be stored in memory1512in some implementations, such as a user interface program that allows for system administration. Data storage1514can take any suitable form, including semiconductor memory, magnetic or optical disk storage, or solid-state drives. Data storage1514is configured to store data used by system1502in controlling the operation of the thermal storage system, including system data1522and historical data1524. In one implementation, system data1522describes the configuration or composition of elements of the one or more thermal storage arrays being controlled. Examples of possible system data include shape or composition of bricks within a thermal storage assemblage, composition of heating elements integrated with an assemblage, and the number of thermal storage assemblages in the thermal storage system. Historical data1524may include data collected over time as the thermal storage system is operated, as well as data from other units in some cases. Data1524may include system log data, peak heater temperatures, peak output gas temperatures, discharge rates of a thermal storage assemblage, a number of heating and cooling cycles for an assemblage, etc. Communications interface1516is configured to communicate with other systems and devices, such as by sending and receiving data and signals between system1502and control systems1504and1506, or between system1502and external analysis system1508. Interface1516is also configured to send control signals to controlled elements of the thermal storage system, and receive sensor signals from sensors for the control system, such as sensors303-1through303-N ofFIG.1. Although shown as a single interface for simplicity, interface1516may include multiple communications interfaces (e.g., both wired and wireless). Control systems1502,1504and1506as illustrated inFIGS.15and16may be implemented in various ways, including using a general-purpose computer system. Systems1502,1504and1506may also be implemented as programmable logic controllers (PLCs) or computer systems adapted for industrial process control. In some cases, systems1502,1504and1506are implemented within a distributed control system architecture such as a Supervisory Control and Data Acquisition (SCADA) architecture. FIG.17is a block diagram illustrating an implementation of external analytics system1508. System1508is configured to provide forecast-based predictions to thermal storage control system1502. System1508includes a processor1530, memory1532, data storage1534and communications interface1536. In one implementation, system1508is implemented in a distributed computing environment such as a cloud computing environment. A cloud computing environment is advantageous in allowing computing power and data storage to be increased on demand to perform intensive analysis of copious amounts of data to provide timely predictions. Processor1530is a processor configured to execute programs stored in memory1532, such as supply forecast program1538, maintenance forecast program1540, market forecast program1542and predictive analytics program1520. Supply forecast program1538includes instructions executable to use weather forecast data and predictive analytics methods to predict power supply availability to the thermal energy storage system. Maintenance forecast program1540includes instructions executable to use system data and predictive analytics methods to predict maintenance requirements for the thermal energy storage system. Market forecast program1542includes instructions executable to use power market data and predictive analytics methods to predict power pricing values or trends for power used by or produced by the thermal energy storage system. Predictive analytics1520includes instructions executable to implement algorithms for analyzing data to make predictions. Algorithms within predictive analytics1520are used by programs1538,1540and1542. Data storage1534stores data including weather data1546, market data1548, supply data1550, thermal storage (TS) data1552, and application (App.) data1554. Data stored in data storage1534may be used by programs stored in memory1532. Weather data1546may include data collected at the location of the power source for the thermal energy storage system along with broader-area weather information obtained from databases. Market data1548includes energy market data received from external data providers. Supply data1550includes data associated with the power source controlled by system1506, and may include, for example, system configuration data and historical operations data. TS data1552includes data associated with the thermal energy storage system, and application data1554includes data associated with the application system controlled by control system1504. Communications interface1536is configured to send data and messages to and from system1502as well as external databases and data sources. Systems and components shown separately inFIGS.15through17may in other implementations be combined or be separated into multiple elements. For example, in an implementation for which an application system like a steam generator is closely connected with a thermal energy storage system, aspects of control systems1502and1504may be combined in the same system. Data and programs may be stored in different parts of the system in some implementations; a data collection or program shown as being stored in memory may instead be stored in data storage, or vice versa. In other scenarios, systems1502or1508may contain fewer program and data types than shown inFIGS.16and17. For example, one implementation of analytics system1508may be dedicated to energy-supply forecasting using weather data, while another implementation is dedicated to power market forecasting using market data, and still another implementation is dedicated to maintenance forecasting using system-related data. Other implementations of analytics system1508may include combinations of two of the three program types shown inFIG.17, along with corresponding data types used by those program types, as discussed above. For example, one implementation of system1508may be configured for both energy-supply forecasting using weather data and power market forecasting using market data, but not for maintenance forecasting using system-related data. Another implementation of the system may be configured for both power market forecasting using market data and maintenance forecasting using system-related data, but not for energy-supply forecasting using weather data. Still another implementation of system1508may be configured for both energy-supply forecasting using weather data and maintenance forecasting using system-related data, but not for power market forecasting using market data. Forecast-Based System Control As noted above, forecast information such as weather predictions may be used by a control system to reduce wear and degradation of system components. Another goal of forecast-based control is to ensure adequate thermal energy production from the thermal energy storage system to the load or application system. Actions that may be taken in view of forecast information include, for example, adjustments to operating parameters of the thermal energy storage system itself, adjustments to an amount of input energy coming into the thermal energy storage system, and actions or adjustments associated with a load system receiving an output of the thermal energy storage system. Weather forecasting information can come from one or more of multiple sources. One source is a weather station at a site located with the generation of electrical energy, such as a solar array or photovoltaic array, or wind turbines. The weather station may be integrated with a power generation facility, and may be operationally used for control decisions of that facility, such as for detection of icing on wind turbines. Another source is weather information from sources covering a wider area, such as radar or other weather stations, which may be fed into databases accessible to by the control system of the thermal energy storage system. Weather information covering a broader geography may be advantageous in providing more advanced notice of changes in condition, as compared to the point source information from a weather station located at the power source. Still another possible source of weather information is virtual or simulated weather forecast information. In general, machine learning methods can be used to train the system, taking into account such data and modifying behavior of the system. As an example, historical information associated with a power curve of an energy source may be used as a predictive tool, taking into account actual conditions, to provide forecasting of power availability and adjust control of the thermal energy storage system, both as to the amount of energy available to charge the units and the amount of discharge heat output available. For example, the power curve information may be matched with actual data to show that when the power output of a photovoltaic array is decreasing, it may be indicative of a cloud passing over one or more parts of the array, or cloudy weather generally over the region associated with the array. Forecast-related information is used to improve the storage and generation of heat at the thermal energy storage system in view of changing conditions. For example, a forecast may assist in determining the amount of heat that must be stored and the rate at which heat must be discharged in order to provide a desired output to an industrial application—for instance, in the case of providing heat to a steam generator, to ensure a consistent quality and amount of steam, and to ensure that the steam generator does not have to shut down. The controller may adjust the current and future output of heat in response to current or forecast reductions in the availability of charging electricity, so as to ensure across a period of future time that the state of charge of the storage unit does not reduce so that heat output must be stopped. By adjusting the continuous operation of a steam generator to a lower rate in response to a forecasted reduction of available input energy, the unit may operate continuously. The avoidance of shutdowns and later restarts is an advantageous feature: shutting down and restarting a steam generator is a time-consuming process that is costly and wasteful of energy, and potentially exposes personnel and industrial facilities to safety risks. The forecast, in some cases, may be indicative of an expected lower electricity input or some other change in electricity input pattern to the thermal energy storage system. Accordingly, the control system may determine, based on the input forecast information, that the amount of energy that would be required by the thermal energy storage system to generate the heat necessary to meet the demands of the steam generator or other industrial application is lower than the amount of energy expected to be available. In one implementation, making this determination involves considering any adjustments to operation of the thermal energy storage system that may increase the amount of heat it can produce. For example, one adjustment that may increase an amount of heat produced by the system is to run the heating elements in a thermal storage assemblage at a higher power than usual during periods of input supply availability, in order to obtain a higher temperature of the assemblage and greater amount of thermal energy stored. Such “overcharging” or “supercharging” of an assemblage, as discussed further below, may in some implementations allow sufficient output heat to be produced through a period of lowered input energy supply. Overcharging may increase stresses on the thermal storage medium and heater elements of the system, thus increasing the need for maintenance and the risk of equipment failure. As an alternative to operational adjustments for the thermal energy storage system, or in embodiments for which such adjustments are not expected to make up for a forecasted shortfall of input energy, action on either the source side or the load side of the thermal energy storage system may be initiated by the control system. On the input side, for example, the forecast difference between predicted and needed input power may be used to provide a determination, or decision-support, with respect to sourcing input electrical energy from other sources during an upcoming time period, to provide the forecasted difference. For example, if the forecasting system determines that the amount of electrical energy to be provided from a photovoltaic array will be 70% of the expected amount needed over a given period of time, e.g., due to a forecast of cloudy weather, the control system may effectuate connection to an alternative input source of electrical energy, such as wind turbine, natural gas or other source, such that the thermal energy storage system receives 100% of the expected amount of energy. In an implementation of a thermal energy storage system having an electrical grid connection available as an alternate input power source, the control system may effectuate connection to the grid in response to a forecast of an input power shortfall. In a particular implementation, forecast data may be used to determine desired output rates for a certain number of hours or days ahead, presenting to an operator signals and information relating to expected operational adjustments to achieve those output rates, and providing the operator with a mechanism to implement the output rates as determined by the system, or alternatively to modify or override those output rates. This may be as simple as a “click to accept” feedback option provided to the operator, a dead-man's switch that automatically implements the determined output rates unless overridden, and/or more detailed options of control parameters for the system. On the output, or load, side of a thermal energy storage unit, various actions may be initiated in response to a forecast-based prediction of an input energy shortfall affecting the output heat to a load.FIG.99illustrates a first forecast energy availability9921(a multi-day forecast of available VRE) and a first controller decision of heat delivery rate (shown as “RATE 1”, and a second, lower forecast9923of multi-day availability of VRE and a second, lower chosen heat delivery rate (shown as “RATE 2”). In one implementation, the controller makes a current-day decision regarding heat delivery rate based on forecast energy availability in the current and coming days so as to avert a shutdown on a future day. In an implementation, a control system of the thermal energy storage system may alert an operator of the load industrial application of the upcoming shortfall, so that a decision can be made. FIG.98illustrates the process9930. At9935, a multi-day charging availability forecast is generated based on a grid power model9933and a weather forecast9931. The energy delivery rate is selected at9937to enable continuous output. At9939, The controller-selected output rate may be presented to an operator either as a notification via email, text message, or other indirect notification, or by a value or icon on a local or remote screen which shows and allows adjustment of the status and operation of the thermal energy storage unit or its associated heat use process; and at9941may receive responding operator input which accepts, rejects, or adjusts the amount or timing of rate adjustment. The information may cause the manual or automatic adjustment at9943of another heat source that supplies heat to the same process, as shown inFIG.97, in such a manner as to achieve a desired overall relatively constant heat supply. Actions that may be taken on the load, or output, side of the thermal energy storage system include adjustment of operation of the load system so that it can operate with the predicted reduction in thermal energy available to it. Alternatively or in addition, the controller may provide commands for the output to be adjusted, and/or adjust the operation of the industrial output itself to compensate for the change in the expected available energy input, and hence the expected available output from the thermal energy storage system. Another possible action in response to a forecast shortfall of input energy is to supplement the output from the thermal energy storage system with an alternate source of that output. In an implementation for which the heated fluid output from a thermal energy storage system is used to generate steam for an industrial process, for example, an alternate source of steam could be an additional steam generator using an alternate fuel source. The control system may provide signals to effectuate connection of the alternate output source to the load system in some implementations. Alternatively, the control system may send a message, such as an instruction or alert, to an operator or controller associated with the load system to indicate the need for connection to the alternate source. In addition to ensuring sufficient output production by the thermal energy storage system to a load, forecast information is used to automatically control the thermal energy storage system to ensure its continued stable operation. For example, when a reduced amount of input power is predicted, the controller may in some implementations adjust the fluid flow rate through a thermal storage assemblage to lower the discharge rate from the assemblage so that the assemblage does not discharge to a point where the associated thermal storage unit shuts down. As another example, the powering of the heater elements may be adjusted to a desired temperature for safety and efficiency, based on the forecast information. For example, if it is expected or forecast that during a future period, the amount of energy from the input source will be less than the expected amount of energy, the system can be configured to “supercharge”, i.e. heat some or all of the bricks in one or more stacks to temperatures higher than normal operation temperatures—for instance, if the normal stack temperature is 1100° C., in case of an expected period of lower energy input, the system can be controlled to heat up to 1300° C. or more for a selected period of time. This can be accomplished by reducing the discharge from certain units and/or by increasing the temperatures of the heater elements. If the forecast indicates an extended period of reduced energy input, such as due to several days of cloudiness, the lead-lag capability of the system explained below may also be modified, because the issue of hotspots and thermal runaway may be somewhat reduced due to the fact that the system will be operating at a temperature that is below the peak temperature. Additionally, in a thermal energy storage system with multiple thermal storage units, if the system cannot be run at full capacity, the controller may reduce or disable charging or completely shut off one or more of the units based on the forecast, such that only a subset of units are operating at full capacity, rather than have none of the units be able to operate at full capacity. In contrast to a situation involving a forecast of reduced power, forecast information may show that the expected electricity availability will meet or exceed the expected amount of energy that is input into the thermal energy storage system. In some implementations, responses of a control system to a forecast of excess energy may include one or more of adjusting operation of the thermal energy storage system to improve system reliability, reducing the amount of input power to the thermal storage energy system, or increasing thermal power to the load. Adjusting operation of the thermal energy storage system may include reducing input power to its heater elements when input energy is available for longer periods, so that a corresponding thermal storage assemblage operates at a lower peak temperature while still delivering sufficient thermal energy output. Such reduction in peak temperature may increase reliability and lifetime of the system. Excess input power supply may allow heating elements to remain powered after a thermal storage assemblage has already been charged with thermal energy, allowing the heating elements to directly heated fluid flowing through a thermal storage assemblage without discharging the assemblage, possibly to use provided such heated fluid to another use. A control system of the thermal energy storage system may cause an amount of energy that is input to the system to be reduced. The energy source or the thermal energy storage system may be coupled to a larger power grid, in which case a reduction in input energy to the thermal energy storage system may be implemented by transferring excess energy to the power grid, e.g., when there is low demand from the system and/or high demand from the power grid to meet other electrical needs. In the absence of a grid connection, a reduction in input energy may be implemented in some implementations by curtailing production from a portion of the energy source infrastructure, such as shutting down certain solar panels in a solar field or wind turbines at a wind farm. Alternatively or in addition to control of the input power supply or thermal energy storage system operation parameters, a response to a forecast of an excess of input energy may be made at the output side of the thermal energy storage system. In an implementation for which electric power is produced at the output of the system (for example, by feeding heated fluid from a thermal storage unit to a steam generator, then passing the produced steam through a turbine), excess power may be transferred to a larger power grid if a grid connection is available, thus providing energy to the grid instead of storing it as heat in the system. In an implementation for which the output to the load is heated fluid, a property of the output fluid may be changed. For example, a higher temperature and/or flow rate of output fluid may be produced. For an implementation in which steam is produced at the output of the thermal energy storage system, a higher vapor quality of the steam may be provided during periods of increased input energy. In some implementations, altered output properties may provide enhanced cogeneration opportunities, through cogeneration systems and methods described elsewhere in this disclosure. The input and output control described above may be interactively controlled in combination, to advantageously adjust the operation of the system. Thus, the controller can use inputs from the forecasting system to account for variations in input energy due to factors such as cloudiness in the case of solar energy, variability in wind conditions for wind generated electricity, or other variability in conditions at the power source. For example, the controller may allow for additional heating, or heating at a higher temperature, prior to a decrease in the forecast availability of input of electricity, based on the forecast information. Additionally, maintenance cycles may be planned based on forecast weather conditions. In situations where the availability of renewable energy is substantially less than the expected energy, such as due to forecast information (e.g., rainy season, several days of low wind cycles, shorten solar day, etc.), maintenance cycles may be planned in advance, to minimize the loss of input energy. Based on the received information, the control system determines and commands, via signals, charging elements, power supply units, heaters, discharge blowers and pumps for effective and reliable energy storage, charging, and discharging. For example, the command may be given to power source controllers for solar energy, wind energy, and energy from other sources. The control system399may also provide instructions to controllers which admit power to the entire heater array or to local groupings of heaters. The control system may include or be in communication with a forecasting and analytics system to monitor real-time and forecasting data corresponding to one or more meteorological parameters associated with an area of interest (AOI) where the electrical energy sources are being installed. The meteorological parameters can include, without limitation, solar radiation, air temperature, wind speed, precipitation, or humidity. The control system, based on the monitored real-time and forecasting data of the meteorological parameters, may in some implementations switch the electrical connection of the system between VRE sources and other energy sources. For instance, when the weather forecast predicts that the availability of sunlight or wind will be lower than a predefined limit for upcoming days, then the control system may command the system to electrically couple the heating elements of the system to other energy sources to meet the demands of a load system for the upcoming days. In another example implementation, the control system monitors real-time and forecast data regarding availability of VRE, and selects an energy discharge rate and command the system to operate at such rate, so as to allow the system to continuously produce energy during the forecast lower-input period. Continuous energy supply is beneficial to certain industrial processes, making it is undesirable for a thermal storage unit to completely discharge itself and shut down. It is also beneficial to certain industrial processes for adjustments in energy supply to be made slowly, and to be made infrequently. Therefore, the control system in some implementations selects a new discharge rate based on a multi-hour or multi-day weather forecast and corresponding VRE production forecast, so as to be able to operate at a fixed rate for (for example) a 24-hour period, or a 48-hour period, or a 72-hour period, given that forecast VRE supply. The control system may additionally and frequently update the information regarding a VRE supply forecast, and may make further adjustments to energy discharge rate so as to meet demand without interruptions, optionally providing signals and interface mechanisms for operator input, adjustment or override as described above. Thus, the behavior of energy delivery is controlled based on the above explained parameters, including forecasting. In addition to forecasting of an input condition such as the weather, forecasting aspects of the thermal energy storage system may also include forecasting of energy markets and available sources and prices of energy, along with supply and demand of the industrial applications at the output of the thermal energy storage system to tune the operation of system. The control system may use the forecast information to control one or more aspects of the thermal energy system, including input of electrical energy, temperature of various elements of the thermal energy storage system, quantity and quality of the output heat, steam, or fluid (including gas), as well as improving the operation of the associated industrial processes. For example, the input electricity may be received or purchased at a time when the cost of the electricity is lower, in conjunction with forecast information about the conditions at the electricity source, and may be output when the demand or pricing of the output from the thermal energy storage system, or of power produced using that output, is higher. Additionally, in situations where there is variability across different time periods as to the forecast conditions, the control system may make the adjustments on a corresponding variable basis. For example, if the expected cost of the input electricity is higher on a first day as compared with a second day, the controller may control the various inputs and outputs and parameters of the thermal energy system to account for differences in conditions between the first day and the second day that are based on differences in the initial forecast. In addition to the foregoing aspects, predictive analytics may be used to more effectively plan for equipment maintenance and replacement cycles. For example, predictive analytics may be used in predicting when maintenance will be needed, based on historical data. These analytics may be used in conjunction with one or more of the above forecast aspects to provide for planned downtime, for example, to coincide with times when input power availability or pricing conditions make operation of the system less advantageous. The foregoing controls may be provided to an operator that makes decisions based on the forecasting information and the operation of the control system. Alternatively, the control system may include some automated routines that provide decision support or make determinations and generate commands, based on the forecast information, in an automated or semi-automated manner. Charging/Discharging Modes As explained above, the system can be operated in a charging mode for storing electrical energy as thermal energy while simultaneously generating and supplying steam and/or electrical power for various industrial applications as required. The charging and discharging operations are independent of one another, and may be executed at the same time or at different times, with varying states of overlap as needed, e.g. to respond to actual and forecast energy source availability and to deliver output energy to varying load demands. The system can also be operated in a discharging mode for supplying the stored thermal energy for steam and/or electrical power generation, as well as other industrial applications. Optionally, the system may be used to provide heated gas to an industrial application directly without first producing steam or electricity. A key innovation in the present disclosure is the charge-discharge operation of the unit in such a means as to prevent thermal runaway, by periodically cooling each element of the storage media well below its operating temperature. In one implementation, this deep-cooling is achieved by operating the storage media through successive charge and discharge cycles in which constant outlet temperature is maintained and each storage element is deep-cooled in alternate discharge cycles. The narrative below refers process flow diagrams1700a-1700hinFIGS.19A through21for charge and discharge, according to the example implementations. AtFIG.19A,1700a, a flow diagram associated with a first charging operating pattern is shown. At1701, power is flowing from an input source of electrical energy such as from a VRE source and operating heaters within stacks1725and1727. At1703, an output of the storage array is shown as steam. As shown at valves1705and1707, the controller1751provides a signal for valve1705(a fluid flow control louver, damper, or other control device) to close for a first thermal storage array, and also provides a signal to a valve1707to be open for a second thermal storage array. Both units are heating, and flow through unit1727is providing flow to deliver heat to the steam generator. With respect to the second unit1727, the second unit is being charged, and flow is provided, as indicated by the valve1707being open. Thus, gas at the input temperature Tlowflows by way of the blower1721, via the dynamic insulation, through the valve1707and through the thermal storage of unit1727to the upper fluid conduit. The gas is heated by the stacks of bricks to an output temperature equal to or above the desired fluid outlet temperature Thigh, which may be a value such as 800° C. A sensor1742may provide information to the controller1751about the temperature of the gas prior to entering the steam generator. The controller1751modulates the setting of valve1741to allow cooler air to mix with the air flowing through the stack of bricks to reduce the blended fluid temperature at point1742to the specified Thighvalue. The hot outlet air continues to flow, including through the steam generator1709, which is supplied with water1719as controlled by pump1717, and cooled air at temperature Tlowis forced by blower1721through the dynamic insulation paths and back to the inlets of valves1705,1707and1741. Additional sensors may be provided throughout the system, such as at1713and1715. The controller1751may also use the same communication and power lines to transmit commands to control elements such as the valves1705,1707. When charging stops, as for example occurs at the end of each solar day or each windy period, discharging continues. InFIG.19B, flow diagram1700bdepicts an example first process flow for the discharging mode without concurrent charging. As shown herein, at the first unit1725, the valve1705remains closed, based on the signal from the controller1751. Thus, there is lower or no gas flow to the first unit associated with the valve1705. On the other hand, the valve1707is open with respect to the second unit1727, based on the signal from the controller1751. Thus, the gas continues to flow through the unit1727, and the controller1751continues to modulate the setting of valve1741to cause the proper amount of cooler air to mix with the air flowing through the stack of bricks to maintain the fluid temperature at point1742to the specified Thighvalue. The hot gas continues to be discharged to the steam generator1709, to generate the steam export1703. As each stack discharges, its outlet gas temperature remains roughly constant until approximately ⅔ of the usable heat has been delivered. At this point the outlet temperature from the stack will begin to drop, and continues dropping as discharge continues. The present innovation uses this characteristic to accomplish “deep cooling” as operation continues. The controller1751senses a reduction in the temperature at point1742and begins closing bypass valve1741. By the time the outlet temperature from unit1727has reached Thigh, valve1741reaches the fully closed position, and as temperature further drops it is no longer possible for unit1727to deliver heat at temperature Thigh. As shown at1700cinFIG.19C, the discharge process is modified to partially open the valve1705based on the signal from the controller1751, so that the first unit1725begins discharging; its higher outlet temperature is now blended with air flowing through cooler stack1727to maintain outlet temperature Thighat point1742. The controller1751now modulates valves1707and1705to vary the flow through stacks1725and1727so as to maintain Thighat point1742. At this point in the discharge process, flow through stack1727emerges at temperature below Thighand is blended with discharge from stack1725which is above Thighin proportions to ensure outlet at1742is maintained at Thigh. Thus, unit1727continues to be cooled by gas flow, and its outlet temperature continues to fall farther below Thigh, while the temperature at1742is maintained at Thighby blending with the higher-temperature air from stack1725. As discharge of stack1725proceeds, its outlet gas temperature begins to drop, and controller1751begins to close valve1707in order to maintain temperature at1742at Thigh. As shown in1700dinFIG.19D, valves1707and1741are closed at the point that the outlet temperature of stack1725has reached Thigh. Note that at this point, the peak brick temperature in stack1727is far below the peak brick temperature in stack1725—it has been “deep-cooled” below Thigh, by continuing to supply flow during the discharge of stack1727. The system would be fully “discharged”—unable to deliver further energy at temperature Thigh—when the outlet temperature of stack1725drops below Thigh. In some implementations, it is beneficial for controller actions to have chosen a rate of discharge such that when next charging begins—as at the beginning of the next solar day, for instance—the system is not yet fully discharged.1700einFIG.20Ashows the next charging period, in which discharging remains constant. Charging energy is again supplied by VRE into both stacks. Stack1727, which has been deeply cooled, is charged without flow, and stack1725is being charged while providing flow to the system output. As the outlet temperature of stack1725rises, controller1751again begins to open valve1741to maintain the blended system outlet temperature at Thigh. At the end of this period of charging (electricity supply is again off), both stacks are fully charged, and discharging continues as in1700fas shown inFIG.20B. Now stack1725is discharging while stack1727has no flow. As discharge proceeds and stack1725's outlet temperature falls, controller1751first begins to close valve1741, then begins to open valve1707as shown in1700ginFIG.20C. Discharging continues; as stack1727's outlet temperature falls, controller1751progressively closes valve1705, so that toward the end of the discharge cycle substantially all flow is coming through stack1727as shown in1700h,FIG.21. As the next charging cycle begins, the system is now in the state shown in1700ainFIG.19A. Thus it will be understood that through actions of the controller responding to the measured and/or modeled state of charge of each stack, in successive charge/discharge cycles each stack is cooled to a gas outlet temperature of approximately Thighin a first cycle and a gas outlet temperature substantially below Thighin a second cycle. This alternating deep-cool operation effectively prevents thermal runaway. Those skilled in the art will recognize that this technique may be applied in larger systems with more than two independent stacks, for instance by organizing the system into pairs which operate as shown here in parallel or in series with other pairs; or by arranging more than two stacks in a deep-cool operating pattern. Flow through the one or both of the stacks may be varied, as explained above. To avoid overheating and to control the output temperature, all or a portion of gas may be diverted by one or more baffles or flow control devices to a bypass1741, controlled by the controller1751, such that the inlet gas is mixed with the discharge gas of the stacks, to provide the output at a constant temperature or specified, non-constant temperature profile. FIG.22also illustrates the charging and discharging modes of a system1800, which includes thermal storage structure1801having first section1803and second section1805. As has been described, system1800can be electrically connected to an electrical energy source, and can facilitate supplying this electrical energy to heating elements1813associated with at least some portion of thermal storage1807within first section1803during a charging mode. Heating elements1813may receive electrical energy at a controlled rate and emit thermal energy such that the bricks can absorb the emitted thermal energy and correspondingly become heated to some desired temperature. As a result, thermal storage1807can store the received electrical energy in the form of thermal energy. As shown, system1800may also be required to simultaneously generate some combination of hot gas, supply steam and/or other heated fluid for various industrial applications. This output may be facilitated within second section1805within thermal storage structure1801, which includes a pump1821that provides water to a first end1817of a conduit1815. Accordingly, during a discharging mode, blower units1823can be actuated to facilitate the flow of a gas such as air from one end to the other of thermal storage1807(e.g., from the bottom to the top), and from there into second section1805such that the gas passing through the first section can be heated to absorb and transfer the thermal energy emitted by the heating elements1813and/or thermal storage. This flow of heated air passes into second section1805, which allows conduit1815to convert the water flowing through the conduit1815into steam and facilitate outflow of the generated steam through a second end1819of conduit1815. Alternatively, during simultaneous charging and discharging, gas flow through thermal storage1807may be minimal or none, and all or a portion of gas from blowers1823may be diverted by one or more baffles or flow control devices, and may be heated by a separate bypass heater (not shown) to deliver inlet gas, such as inlet air, to the steam generator at a suitable temperature. This bypass mode of operation may be beneficial in achieving predefined temperature distributions in thermal storage and in mitigating the required power dissipation of the heating elements. In some configurations, the only required output from the thermal storage structure is the output of hot gas (e.g., hot air) to an industrial process. Accordingly, a steam generator may either not be present or not used. In such configurations, a separate conduit connecting to a processing chamber may be provided to facilitate delivery of the hot gas. In another implementation, if the available electrical energy being received by the structure1800is low, then during charging mode, a smaller number of the total number of available heating elements1813receive the limited available electrical energy. Accordingly, only a portion of thermal storage is heated during charging mode. During discharging, gas can be passed largely through only the portion of thermal storage1807that has been heated. The heated gas thus continues to transfer the stored thermal energy to the conduit1815in order to keep the temperature of the gas at the conduit1815sufficiently high to maintain continuous and controlled steam production, thereby preventing any damages or failure in the steam production system. Simultaneous Charge-Discharge Alternate Heater Implementations discussed above have described the flow of a fluid such as air into a first section of a thermal storage structure that includes the thermal storage material itself, and from there into a second section of the thermal storage structure that includes an output device such as a steam generator. Other fluid flows within the thermal storage structure are also contemplated. In some implementations, the system is configured to cause a heated air flow to be directed into the second section, without first having flowed through the first section. In such implementations, the system is configured to heat inlet air using a heater that is electrically connected to the electrical energy sources. In this manner, the air may be heated to a same temperature range that would be expected from heated air being output from the thermal storage. This mode may be utilized in charging mode, during which time the energy supply from the electrical energy source is likely to be plentiful, and therefore less costly. A heater powered by the input electrical energy receives inlet air (e.g., which may be ambient air, recirculated air, etc. that is cooler than the peak temperatures of air produced by the thermal storage), heats the inlet air, and directs it to the second section of the thermal storage structure, where it may pass over a conduit of an OTSG, for example. During this operation, the system may allow very little or no air to pass through the thermal storage such that charging is performed efficiently without discharging into the second section before discharging mode is initiated. In another type of air flow, the thermal storage structure can be configured to facilitate the passive outflow of heated air from the housing due to the buoyancy effect of heated air. This may be used to provide intrinsic safety for people working in areas near the unit and for the equipment itself, without requiring active equipment or standby electric power sources to maintain safe conditions. For example, if pump or blower motors or drives fail, if control systems fail, or if the operating electric power supply fails, the present innovations include features that cause air to flow in such a manner as to provide ongoing cool temperatures at exterior walls, foundation, and connected equipment points. This type of operation can maintain the temperature of all parts of the system within safety limits and prevent any potential harm to people, the environment, other equipment or the components of the system from being thermally damaged. FIG.18is a block diagram of a system1600that illustrates these air flows. As shown, thermal storage structure1601includes a first section1603that includes thermal storage blocks1607, a second section1605that includes a steam generator1615, and a thermal barrier1625separating the two sections. Further, as described above, insulation is provided with an air gap that allows for the dynamic insulation of thermal storage1607. A blower1621takes inlet air from louver1619and directs it to thermal storage blocks1607. Air that has passed through the thermal storage blocks1607can then pass into second section1605during a discharging mode. As an example of another air flow, release valve1623may be controlled to allow for the release of hot air, and inlet valve1619may be opened to allow for the intake of ambient air, such as in the event of a need for quick shutdown or emergency. By suitable arrangement of the valve locations and air flow paths, a “chimney effect” or buoyancy-driven air flow may establish suitable air flow through the dynamic insulation and system inlets to maintain cool outer temperatures and isolate the steam generator or other high-temperature process from the storage core temperatures, without active equipment. Auxiliary heater1609is a type of auxiliary heater that can be used to heat a portion of the fluid (such as air) moving through the thermal storage structure. As shown inFIG.18, auxiliary heater is positioned in the thermal storage structure, but may also be located outside of the thermal storage array. In the case of the auxiliary heater1609being positioned in the thermal storage structure, the portion of the fluid may pass through the bypass described below with respect toFIGS.19A-19D,20A-20C and21-33. Another type of auxiliary heater that may be used in some implementations is a heater positioned between the fluid output of a thermal storage medium and an inlet of a load system that the fluid is delivered to. Such a heater may be used in some embodiments to increase an output temperature of the fluid provided by a thermal storage structure. These are just two examples of multiple possible fluid flows within system1600. As has been described, system1600is configured to receive inlet fluid at inlet valve1619. This fluid may variously be directed directly to the dynamic insulation or directly to thermal storage1607. Optionally, the system can include one or more louvers1611positioned at the bottom of the stacks within first section1603, and are configured such that the flow path of the fluid flowing through each of the storage arrays and thermal storage elements is as uniform as possible such that constant air pressure is maintained across each thermal element for efficient charging and discharging. Still further, inlet fluid may be directed to second section1605via auxiliary heater1609, as controlled by a louver1611positioned between the blower1621and the auxiliary heater1609, without passing through the dynamic insulation or thermal storage1607. Additionally, fluid flow from the top of the stacks within thermal storage1607may be provided to steam generator1615via a valve1613between first section1603and second section1605. Valve1613can separate receive fluid flows produced from each of the stacks in thermal storage1607. For example, in the case in which two stacks are used, valve1613can receive a first fluid flow from a first stack and a second fluid flow from a second stack. Valve1613can also receive a bypass fluid flow, which corresponds to fluid (such as from louver1619) that has not passed through either the first or second stacks. As will be described below in the context of the lead-lag paradigm, valve1613is controllable by the control system to variously output no fluid, a combination of the first fluid flow and the bypass fluid flow, a combination of the second fluid flow and the bypass fluid flow, a combination of the first and second fluid flows, etc. In order to achieve an output fluid having a specified temperature profile. Louver1619can also be used to release cool fluid from the system instead of recirculating it to thermal storage1607, in the event that the blower is not operational, for example. While the foregoing example includes the bypass heater louvers, such as high-temperature louvers, these features are optional. Further, the bypass heater may have an advantage, in that it can reduce the required heater power within the array. In other words, the bypass heater may discharge heat during charging, without passing air through the array during charging. Note that various other control valves are contemplated, including those described below with reference toFIGS.35(A)-(B). These air flows and associated control structures may provide benefits in terms of safety and temperature regulation, in addition to the benefit of efficient charging and discharging. The selection of charging and discharging modes may be made by a control system on an automatic schedule based on, for example, measurements of temperature or power distribution. Similarly, other features such as the hot air booster mode described above may also be controlled by the control system based on conditions detected within the thermal storage structure. Such sensing may include measurements of radiation by cameras, spectrometers, or other devices, and may include remote measurements carried by optical waveguide systems including fiber optic, fixed reflector, and movable reflector systems; measurements of temperature based on measurements of resistance or current flow in heating elements; direct sensing of temperatures within the refractory array, within flow channels exiting the array, or by other sensing means or locations. Next, the use of a particular type of discharging—“deep discharging”—is described. Lead-Lag and Avoiding Thermal Runaway Thermal energy storage systems are vulnerable to “thermal runaway” or “heat runaway” effects. The phenomenon may arise from imbalances in local heating by heating elements and imbalances in local cooling by heat transfer gas flow. Even small imbalances may be problematic, which are amplified across successive charge-discharge cycles. After several cycles, even small imbalances may result in large temperature differences which may be damaging to bricks and/or heaters, and/or severely limit the temperature range within which the system can be safely operated. FIG.23provides an example2000illustrating how heating imbalances within heating storage arrays may lead to thermal runaway. For each of multiple points in time, example2000depicts temperatures associated with fluid flow conduits2010and2020, each of which passes through a different thermal storage array. (For ease of reference, the arrays through which conduits2010and2020pass may be referred to as arrays 1 and 2, respectively). As shown, different portions or layers of the conduits are heated by different heating elements, indicated as heating element pairs2031A-2036A and2031B-2036B. Point in time2050corresponds to an initial, fully charged state for both arrays 1 and 2. In this state, the conduits are heated to 1000° C. along each section of their lengths. In the case of solar energy input, such a state might to correspond to arrays at the end of a solar day. While the value of 1000° C. is included, this is just an example, and the temperature may be varied depending on factors such as applications or use points. For example, the conduits may be heated within a range of 800° C. to 1600° C., and more specifically, 900° C. to 1300° C., and even more specifically, 800° C. to 1100° C. Other factors that may impact the temperature include temperature impact on heater life, storage capacity, heating patterns, weather conditions, temperature, and heater materials. For example, a ceramic heater may have an upper conduit temperature range as high as 1500° C. to 1600° C., whereas other heaters may have a conduit temperature range of 600° C. to 700° C. The range of conduit temperatures may be varied vertically within the stack by varying the brick materials. At the beginning of discharge period2051(e.g., dusk in the case of solar energy input) of the arrays, cooler heat transfer gas is introduced at the bottom of the arrays and flows upwards. During the charging period that has just concluded, heat has been added by heating elements2031-2036, which may be oriented transverse to the fluid columns and grouped by horizontal position within the array. Ideally, the same input energy will have been supplied to all heating elements in each group, but in practice, individual heating units vary slightly in their resistance (and thus their power delivery). Similarly, local cooling flow rates will vary between conduits, given that individual channels vary in roughness, brick alignment, or are otherwise mismatched in their resistance to flow. Here, example2000assumes that the flow rate in conduit2020is below the flow rate in2010. Accordingly, portions of array 2 adjacent to conduit2020will exhibit higher temperatures than portions of array 1 adjacent to conduit2020, due to the lower cooling flow. The result at the end of discharge period2051is shown inFIG.23. Arrays 1 and 2 both exhibit a “thermocline” temperature distribution, as the bricks at the lower layers of arrays 1 and 2 are cooler than those at the upper layers. This phenomenon results from the discharge period being stopped when a particular outlet temperature (i.e., a temperature at the top of the array)—600° C. in the case of array 1. Furthermore, due to the lower cooling flow in array 2, material temperatures around conduit2020in array 2 are roughly 300° C. higher than those around corresponding layers of conduit2010in array 1. For example, the top layer of array 1 is at 600° C., while the top layer of array 2 is at 900° C. These variations in heating and cooling rates, unless managed and mitigated, can lead to runaway of mismatched storage element temperatures, and can lead to runaway temperatures that cause failures of heaters and/or deterioration of refractory materials within the array. At the end of discharge period2051, the control system determines how much energy to apply to each heating element group during a charging (or recharging) period in order to restore the full state of charge. But the control system may not have information about every temperature nonuniformity within every location within a set of thermal storage arrays. For example, there might be a limited number of sensors available, and thus temperature nonuniformities may be undetected. Sensors may also malfunction. In some implementations, the heating elements may be controlled by a model-based paradigm in which sensors are not used or are used in a limited fashion. The system may also not be configured to vary heating to a fine enough granularity to resolve every area of temperature nonuniformity. In example2000, it is determined that heating elements2031are given enough total energy to raise the surrounding materials by 800° C., while heaters2036are given enough energy to raise their surrounding materials by 400° C. At the end of a charging period2052that uses the above-noted heating parameters, the temperature differences at the end of discharge period2051remain. This is due to inefficient discharging of conduit2020relative to conduit2010, and conduit2020's higher residual temperature at the end of discharge period2051. Accordingly, the amount of input energy received during charging period2052overheats conduit2020along its length by roughly 300 degrees. Note that over the course of a single discharge and charge cycle, temperatures along conduit2020are now 250-300° C. warmer as compared to fully charged state250. If another cycle were repeated (that is, another discharge period followed by another charge period), the overheating of conduit2020would be even more pronounced. (The values shown inFIG.23are for example purposes; realistic temperature mismatches might grow more slowly, but could reach a critical level over repeated cycles.) This increase in temperature over time due to local temperature nonuniformities is thermal runaway, and can cause early failure of heating elements and shortened system life. An effect that exacerbates this runaway is the thermal expansion of fluid flowing in the conduits. Hotter gas expands more, causing a higher outlet velocity for a given inlet flow, and thus a higher hydraulic pressure drop across the column. This effect may contribute to a further reduction of flow. The present disclosure teaches several techniques that may be used to mitigate thermal runaway in a manner that achieves long-term, stable operation of the thermal energy storage system. First, the height of the storage material stack and the physical measurements of the fluid flow conduits may be chosen in such a manner that the system is “passively balanced.” Low fluid flow rates are selected for system discharge, and flow rates and conduit geometries are designed with a relatively low associated hydraulic pressure drop and long column length. In this configuration, the lower density of hotter gas will create a “stack effect,” a relative buoyancy component to the flow rate, which increases fluid flow in hotter conduits. This mismatched cooling flow provides a balancing force to stabilize and limit temperature differences across the thermal storage array. Second, a “deep-cool” sequencing is used to rebalance or level temperature differences among conduits. This concept can also be referred to as a deep discharge (also referred to as “deep-discharge”). Generally speaking, deep discharging refers to continuing discharge of one or more arrays until temperature nonuniformities within the array have reduced (such arrays can thus be said to have been “deeply discharged,” which amounts to a thermal reset). The amount of discharge of an array might be measured in several ways, such as by a comparison of the array's total bulk temperature to that of the inlet gas temperature from inlet or bypass air admitted through an inlet valve. A deep discharge of an array may be contrasted with a partial discharge of the array, in that during a deep discharge, gas flows through the array for a longer period of time (and potentially with greater flow volume) than during a partial discharge. In some applications of a deep discharge, an array may be fully discharged to the inlet air temperature, which may also be referred to as bypass temperature. The operations sequence shown inFIGS.19A-21disclose one “deep discharge” method of operation. Consider the effect of deep-discharge period2054. By discharging arrays 1 and 2 more completely than in discharge period2051(e.g., by flowing gas over the arrays for a longer period of time), it can be seen that arrays 1 and 2 discharge more uniformly during deep-discharge period2054. Temperatures in array 1 range between 300-310° C., while temperatures in array 2 range between 310-480° C. Accordingly, subsequent charging period2055results in a temperature distribution within both arrays 1 and 2 that more closely approximates starting point2050, and thus greatly reduces thermal runaway within the thermal storage. Deep discharging is thus an effective solution to the problem of thermal runaway within a thermal storage array. But thermal runaway is not the only constraint on the thermal energy storage systems contemplated in this disclosure. As noted, it is desirable for thermal energy storage systems to be able to provide a continuous or near-continuous supply of thermal energy for downstream processes. This requires that at least some media within the storage unit be at temperatures above the required delivery temperature. The present inventors have realized that while deep-discharge is desirable for thermal storage arrays, discharging all arrays in a system every discharge cycle is not possible, as it would create periods when no element within the system has sufficient temperature to meet outlet temperature requirements. Accordingly, the inventors have developed a paradigm of only periodically deep-discharging each thermal storage array in a set of one or more storage arrays. This approach meets the dual objectives of periodically performing a thermal reset of each thermal storage array and maintaining sufficient temperature within the thermal storage to meet outlet temperature specifications. One specific implementation that is contemplated includes the use of two thermal storage arrays, and is referred to as the “lead-lag” technique. In this technique, the system deep-discharges each of the two thermal storage arrays every other discharge period. For example, array 1 would be discharged in discharge periods 0, 2, 4, etc. and array 2 would be discharged in discharge periods 1, 3, 5, etc. The process elements for a lead-lag operation are shown inFIGS.19A through21, and the conceptual lead-lag temperature profiles are shown inFIGS.24and25, which illustrate the discharge temperature of a first stack and a second stack in a thermal energy storage system, as well as a temperature of a blended fluid flow that is provided as an output. FIG.24Aillustrates an example configuration24000associated with the concept of lead-lag. More specifically, a first stack24001and a second stack24003are provided that are each configured to receive inlet fluid, as well as a bypass24005, which is also configured to receive inlet fluid. Respective valves24007,24009, and24011control airflow into the first stack24001, the second stack24003and the bypass24005, based on inputs received from the controller, as explained above with respect toFIGS.19-21. The control of the flow will be explained below with respect toFIGS.24-33. As shown in chart2060Aa, temperature is shown along the vertical axis, while time is shown along the horizontal axis. A peak temperature2061of the first stack and the second stack are shown, along with bypass temperature2063, which is the inlet gas temperature. Additionally, at2065, a delivery temperature of the stream of blended output fluid flow is shown. The horizontal axis shows time, including 24-hour intervals2067and2067a, as well as a solar day at2069and2069a. The peak temperature of the first stack is indicated by line2071, while the peak temperature of the second stack is indicated by line2073. As will be shown, the first stack and the second stack operate together such that the first stack is in a “lead” mode of operation when the second stack is in a “lag” mode of operation, and vice versa. During the first day, the first stack is cooled to a very low temperature relative to both peak temperature2061and delivery temperature2065, while the second stack is cooled to a minimum required temperature to deliver the output at the delivery temperature2065, which is shown here as a constant. On the second day, the second stack is cooled to the lower temperature while the first stack is cooled to the delivery temperature. In short, in the case where two stacks are operating together, each stack may be deeply discharged to well below the delivery temperature every other discharge period. Similarly, in those discharge periods in which a given stack is not being deeply discharged, it is discharged from the peak discharge temperature to the delivery temperature (or a temperature approaching the delivery temperature). The cycling between the lead mode and the lag mode for a given stack is accomplished by the control system controlling the flow of fluid in each of the stacks. (In the lead mode, a given stack is deeply discharged, while in the lead mode, the given stack is discharged to a temperature at or above the delivery temperature.) The stack that is being deeply discharged may continue to be heated by having the resistive heating elements receive the electrical energy and emit heat; alternatively, the resistive heating elements may be switched to an off state. At the leftmost position of the chart2060Aa, the first stack and the second stack are both at the peak temperature2061. This starting position may occur outside the solar day such as at midnight. Then, as indicated by line2071, the first stack begins discharging. As the temperature of the first stack starts to fall and continues to fall to below the output delivery temperature, hot fluid from the second stack is blended as shown at2073. As the temperature of the first stack continues to fall, the flow through the first stack is reduced and additional heated fluid is blended in from the second stack, in order to maintain delivery temperature2065. The first stack continues to discharge until it reaches or approaches a minimum temperature, which, in this example, corresponds to bypass temperature2063and represents a fully discharged state of the first stack. This minimum temperature is, in some cases such as in chart2060A, a temperature that approximates the bypass temperature. The degree to which the minimum temperature approximates the bypass/inlet gas temperature may depend on factors such as the quality of heat transfer out of the bricks, as well as a difference between delivery temperature2065and peak temperature2061. For example, if peak temperature2061were 1000° C. and delivery temperature2065were 900° Celsius, the amount of cool air that can be blended into the air that is 1000° C. is relatively small. Thus, minimum temperature2063to which the stack can be cooled may be higher, such as 800° C. On the other hand, if the delivery temperature2065were lower, such as 650° C., then the minimum temperature2063to which the stack can be deeply cooled may be lower, such as around 200° C. Thus, the lower delivery temperature2065is relative to peak temperature2061, the lower minimum temperature2077can be set relative to bypass temperature2063. Thus it is not necessarily the case that a stack must be discharged to the bypass temperature in order to achieve deep discharging. Rather, discharging may occur within a range of temperatures (a “deep-discharge temperature region”) that is sufficient to reduce thermal runaway by reducing thermal nonuniformities. In some cases, the range of a deep-discharge temperature region for a particular use case is bounded on the upper end by the delivery temperature and on the lower end by the inlet gas temperature, the bounds including both the delivery temperature and inlet gas temperature (or bypass temperature) in the region. As noted, the bounds for this region for a particular situation will vary, for example based on the peak temperature and delivery temperature, and may be more specifically determined in some cases by monitoring the thermal behavior of the thermal storage arrays. Alternately, a deep-discharge temperature region may be determined via execution of a computer modeling program. During the deep discharging of the first stack, the bypass valve may be turned off, such as by starting to close the louver on the bottom of the stacks as controlled by the control system, to accelerate the cooling process. At this point, the second stack is being used as the primary source of heated fluid to provide the blended stream at delivery temperature2065. Further, as explained above, fluid may be flowed through the fluid bypass valve so that the fluid is provided at the inlet temperature to the blended stream. The fluid bypass may be used to bypass fluid directly to the blended fluid flow, in order to bring the temperature down at a time when both of the stacks become too hot, such as towards the end of the solar day. As the second stack continues to discharge, its discharge temperature starts to approach the delivery temperature2065, as shown at2081. The discharge may be buffered, such that the minimum discharge temperature of the second stack is higher than the constant delivery temperature2065, as shown at2081z. This temperature of the second stack is the minimum temperature at which the blended stream can be provided at delivery temperature2065. Here, the temperature of the first stack at2079is substantially cooler than the temperature of the second stack at2081. At this point, which is at or around the start of the solar day (e.g., dawn), the flow to the first stack is turned off at2079, and the first stack begins to charge as shown by a broken line2083inFIG.24. At this point, the heaters are on for both the first stack and the second stack. Because there is no fluid flow through the first stack, however, the slope of the line indicating heating is greater than that of the second stack, in which fluid flow is occurring. Alternatively, as shown in25, fluid continues to be trickled through the first stack as it increases its discharge temperature. The trickle may account for the possibility that the units are not sealed in such a manner that would permit 0% flow, and that the louvers permit a residual flow, such as 5% or the like. Further details of this approach are explained with respect toFIG.28. Returning toFIG.24, after a period of charging, both the first stack and the second stack become fully charged by2085, which, in this example, occurs during the solar day. In this example, the second stack continues to provide the hot fluid output at the peak temperature while the first stack continues to charge between2085and2087. On the other hand, louvers of the first stack are fully closed at this point, such that there is essentially no fluid flow through the first stack. At2087, the roles of the first stack and the second stack are reversed, such that the second stack begins to discharge to a deeply discharged state while the first stack continues to provide the fluid for the blended stream, so as to maintain constant delivery temperature2065. The remainder of the timeline shown inFIG.24is similar to that described for the first 24-hour interval. At the end of the first 24-hour period cycle2067and the start of the second 24-hour period cycle2067a(i.e., at2087), the second stack and the first stack are both at peak temperature2061. As can be seen at2071a, the second stack begins discharging. As the temperature of the second stack starts to fall and continues to fall to below the delivery temperature, hot fluid from the first stack is blended at2073a. As the temperature of the second stack continues to fall, the flow through the second stack is reduced and additional heated fluid is blended in from the first stack to maintain delivery temperature2065. The second stack continues to discharge, such as until it reaches a minimum temperature at2077aor other discharge temperature. During the deep discharging of the second stack, the bypass valve may be turned off, such as by starting to close the louvre on the bottom of the stacks as controlled by the control system, to accelerate the cooling process. At this point, the first stack is being used as the primary source of heated gas to provide the blended stream at delivery temperature2065. As the first stack continues to discharge, its discharge temperature starts to approach delivery temperature2065, as shown at2081a. The discharge may be buffered, such that the minimum discharge temperature of the second stack is higher than the constant delivery temperature2065, as shown at2081za. This temperature of the first stack is the minimum temperature (or approximately the minimum temperature) at which the blended stream can be provided at delivery temperature2065. Here, the temperature of the second stack at2079ais substantially cooler than the temperature of the first stack at2081a. At2079a, which is at or around the start of the solar day, the flow to the second stack is turned off, and the second stack charges as shown by broken line2083aofFIG.24. At this point, the heaters are on for both of the second stack and the first stack. Alternatively, as shown inFIG.25, fluid continues to be trickled through the second stack as it increases its discharge temperature. The trickle may account for the possibility that the units are not sealed in such a manner that would permit 0% flow, and that the louvers permit a residual flow, such as 5% or the like. Further details of this approach are explained with respect toFIG.28. The first stack continues to provide the hot fluid at the peak discharge temperature while the second stack continues to charge between2085aand2087a. On the other hand, louvers of the second stack are fully closed at this point, such that there is essentially no fluid flow through the second stack. This pattern of having a lead stack and a lag stack repeats (e.g., every 48 hours). Accordingly, the first discharge operation in discharge period of2067d1and the second discharge operation in successive discharge period2067d2can be repeated, such that the control system alternates between performing the first discharge operation (deep-discharging the first stack but not the second stack) and the second discharge operation (deep-discharging the second stack but not the first stack) over time, allowing the system to continuously provide an output fluid flow, and to do so while avoiding thermal runaway. This approach need not be limited to a first stack and a second stack, and may be used with more than two stacks (e.g., triples, quads, or the like) as will be described further below. FIG.26provides a detailed illustration of the temperature and gas flow according to the lead-lag implementation. The common features withFIG.24are indicated with common reference numerals in chart2060B, including a peak temperature2061b, a bypass temperature2063band a delivery temperature2065b. Further, a 24-hour period2067band a solar day2069bare shown along the horizontal axis. Air flow is also indicated along the right side ofFIG.26. While the description accompanyingFIG.26refers to hot air flow, it can also be generalized to refer to fluid flow. At the left side of chart2060B, the beginning of the timing shown is associated with an end of the solar day. At this point the first stack and the second stack are both at the peak temperature, in this case 1000° C. At2071b, the first stack is discharging hot air at 1000° C., while the second stack is not discharging hot air as indicated at2070b, with an air flow of 0%. As explained above, the discharge temperature may vary between 800° C. to 1600° C., depending on various factors. The temperature of the bricks approaches the temperature of the conduit, usually within 25° C. to 50° C. For example, the conduits may be heated within a range of 800° C. to 1600° C., and more specifically, 900° C. to 1300° C., and even more specifically, 800° C. to 1100° C. Other factors that may impact the temperature include temperature impact on heater life, storage capacity, heating patterns, weather conditions, temperature, and heater materials. For example, a ceramic heater may have an upper conduit temperature range as high as 1500° C. to 1600° C., whereas other heaters may have a conduit temperature range of 600° C. to 700° C. The range of conduit temperatures may be varied vertically within the stack by varying the brick materials. Both of the stacks contain very hot air at the end of the solar day; the bypass unit is flowing in air at the inlet air temperature as the deep-discharge temperature2063b. As the flow of the first stack increases from about 60% to 100%, e.g., 60% to 100%, of the total airflow as indicated by2072b, the discharge temperature of the first stack starts to decrease at2073b. As the discharge temperature of the first stack starts to decrease, the bypass flow is also decreased downward from about 40%, e.g., 40%, of the total air flow. When the discharge temperature at the first stack falls below delivery temperature2065b, as depicted at2075b, the flow of the first stack is now 100% of the total airflow as indicated by2077b, and the flow of the bypass and the second stack are both 0%, as indicated by2076b. At this point, in order to maintain the delivery temperature of the blended air at2065b, air flow is turned on to the second stack at2076b. As the air flow at the second stack increases and the air flow at the first stack decreases, the first stack continues to cool, but the rate of cooling slows as the flow through the second stack is reduced, as shown at2078b. Conversely, as the air flow at the second stack increases, the second stack begins to cool, and as the air flow of the second stack approaches 100% of the total air flow at2074b, the discharge temperature at the second stack starts to rapidly decrease until it reaches the constant delivery temperature as shown in2079b. At this point, the air flow of the first stack is 0% as shown at2080b. Once the discharge temperature of the second stack reaches the minimum temperature at which the constant delivery temperature2065B can be maintained (as indicated by2079b), the airflow through the second stack is decreased, and the discharge temperature of the second stack correspondingly rises at2082b. At the same time, because this is occurring during the late solar day, the bypass flow is used to prevent overheating at2076b′. Further, because there is no flow through the first stack, the discharge temperature of the first stack increases rapidly as the first stack charges, as indicated by2081b. At2083b, the first stack and the second stack have discharge temperatures equal to or approaching peak temperature2061b. At2083b, the 24-hour cycle is now complete. The first and second stacks now switch roles, such that the second stack will “lead” and undergo deep cooling, and the first stack will “lag” and act as the second stack did in the first 24-hour cycle. The bypass will continue to operate in a similar manner. A second 24-hour period2067baand a solar day2069baare indicated along the horizontal axis. At the end of the first 24-hour period cycle2067band the start of the second 24-hour period cycle2067ba(i.e., at2087ba), the timing is associated with an end of the solar day. At this point the second stack and the first stack are at the peak temperature, in this case 1000° C. As shown at2071ba, the second stack is discharging hot air at 1000° C., while the first stack is not discharging hot air as indicated at2070ba, with an air flow of 0%. As before, the bypass unit is flowing in air at the inlet air temperature (deep-discharge temperature2063b). As the flow of the second stack increases from about 60% to 100%, or 60% to 100%, of the total airflow as indicated by2072ba, the discharge temperature of the second stack starts to decrease at2073ba. As the discharge temperature of the second stack starts to decrease, the bypass flow is also decreased downward from about 40%, or 40%, of the total air flow. When the discharge temperature at the second stack falls below the constant delivery temperature2065b, as depicted at2075ba, the flow of the second stack is 100% of the total airflow as depicted at2077ba, and the flow of the bypass and the first stack are both 0%, as depicted by2076ba. At this point, in order to maintain the constant delivery temperature of the blended air at2065b, air flow is turned on to the first stack at2076ba. As the air flow at the first stack increases and the air flow at the second stack decreases, the second stack continues to cool, but the rate of cooling slows as the flow through the first stack is reduced, as shown at2078ba. Conversely, as the air flow at the first stack increases, the first stack begins to cool, and as the airflow of the first stack approaches 100% of the total airflow at2074ba, the discharge temperature at the first stack starts to rapidly decrease until it reaches the constant delivery temperature as shown in2079ba. At this point, the air flow of the second stack is 0% as shown at2080ba. Once the discharge temperature of the first stack reaches the minimum temperature at which delivery temperature2065bcan be maintained (i.e., at2079ba), the air flow through the first stack is decreased, and the discharge temperature of the first stack correspondingly rises at2082ba. At the same time, because this is occurring during the late solar day, the bypass flow is used to prevent overheating at2076ba. Further, because there is no flow through the second stack, the discharge temperature of the second stack increases rapidly as the second stack charges, as indicated by2081ba. At2083ba, the second stack and the first stack have discharge temperatures equal to or approaching peak temperature2061b. Structures such as valves, blowers, louvers and other mechanisms needed to accomplish the above-described operations are operated in response to commands received from the control system. The control system is configured to generate the instructions based on a variety of information, including a combination of sensed information, forecast information, and historical information, as well as models developed based on, for example, artificial intelligence. For example, sensors may be provided to ensure that the system is safe, in combination with a physical model of how the system performs with different inputs in energy—this model may thus serve as a substitute for some sensors in various embodiments. In some cases, sensors may be expensive and may wear out or need replacement, and could cause additional problems. For example, a defective sensor may lead to system overheating. The model may take temperature inputs, and may allow for predictions based on parameters such as sunrise and weather. The model may be adjusted based on the industrial application for a variety of reasons, such as to optimize output temperature, energy output, or a combination thereof. As has been described with reference to2060B, the control system is configured to direct fluid flows (e.g., a first flow associated with the first stack, a second flow associated with the second stack, and a bypass flow that bypasses the first and second stacks) in order to deeply discharge the first stack but not the second stack during first discharge period2069bd1and to deeply discharge the second stack but not first stack during second discharge period2069bd2. The operations of the first and second discharge periods may be performed repeatedly in successive discharge periods, alternating between the operations of2069bd1and2069bd2. In the first discharge period, the second stack is discharged to a lesser degree than the first stack—to the current value of the specified temperature profile. Similarly, in the second discharge period, the first stack is also discharged to a lesser degree than the second stack—to the current value of the specified temperature profile. The specified temperature profile2065bshown inFIG.26is a constant temperature profile, but such temperature profiles may vary, as will be described with respect toFIG.29. It is understood that these temperature and flow illustrations are just examples, and the actual values and shapes of curves may vary. As one simple example, the peak temperature may be reduced during summer. Some examples of variations are provided as follows. FIG.27provides a detailed illustration2060C of a temperature and fluid flow according to the lead-lag implementation, accounting for incomplete discharge of the second stack, in order to have a buffer between the constant output temperature and the discharge temperature of the second stack at its lowest point in the cycle. The ability of the system to discharge the second stack to the constant output temperature depends on variables such as weather forecast, season, length of solar day. The practice of incomplete discharge thus avoids the undesirable discharge to below the constant output temperature. Features common toFIGS.24-33are given similar reference numerals. Instead of having the temperature of the second stack fall precisely to output temperature2065c, the temperature may fall to a buffered amount2085cthat is slightly higher than the constant output temperature2065c. In other words, the second stack does not completely discharge, but only partially discharges. On the other hand, the first stack continues to have the same temperature and air flow pattern as inFIG.26as explained above. The partial discharge may be accomplished by adjusting the flow2084cof the second stack, so that it is less than 100% of the total flow, for example approximately 90%, e.g., 90%, of the total flow. To compensate for the 10% of the total flow, the bypass is opened when the desired second stack discharge (buffer) temperature2085cis reached, as shown at2086c. At2087c, the bypass and the second stack air flow essentially follow the air flow as shown above inFIG.26. The value of 10% is just an example, and may be varied depending on the discharge temperature, return air temperature, target heat content or target temperature of the output, the flow percentage through each stack, as well as the temperature of the stacks. Similarly, during a second 24-hour cycle, the temperature of the first stack fall may fall to an amount2085cthat is slightly higher than constant output temperature2065c. Thus, the first stack only partially discharges. The second stack has the same temperature and air flow pattern as described inFIG.26. As with the first 24-hour period, the partial discharge may be accomplished by adjusting the flow2084caof the first stack, so that it is less than 100% of the total flow, for example approximately 90%, e.g., 90%, of the total flow. To compensate for the 10% of the total flow, the bypass is opened when the desired first stack discharge temperature2085cais reached, as shown at2086ca. As explained above, the value of 10% is just an example, and may be varied depending on the discharge temperature, return air temperature, target heat content or target temperature of the output, the flow percentage through each stack, as well as the temperature of the stacks. Accordingly,2060C illustrates that the control system is configured maintain an output fluid flow at a specified constant temperature profile (2065c), while, in successive discharge periods2069cd1and2069cd2, alternating between 1) deeply discharging the first stack while discharging the second stack to a first buffer temperature (2085c) above the specified temperature profile, and 2) deeply discharging the second stack while discharging the first stack to a second buffer temperature (2085ca) above the specified temperature profile. FIG.28provides a detailed illustration2060D of a temperature and fluid flow according to the lead-lag implementation, accounting for charging of the low-flow lag stack, in which air continues to be trickled through the first stack as it increases its discharge temperature. The trickle may account for the possibility that the units are not sealed in such a manner that would permit 0% flow, and that the louvers permit a residual flow, such as 5% or the like. While the value of 5% is provided, it is noted that louvers generally cannot be closed 100%, but can approach being −99%. The reason for this is because of thermal expansion tolerances, differences between materials in the louvers and bricks, and the like. The residual flow may approach 5%, and may vary during the period, as shown inFIG.28. The louver is less open at beginning of charge to prevent entry of cooler air. As the charge progresses, the residual flow is increased, as warmer air has a less negative impact due to the entry of the cooler air. Over time, the residual flow may be increased to 5%, or even 10%. The upper bound may be defined based on when trickle flow becomes prohibitively large such that hot spot gets hotter, as an example. Features common to previousFIGS.24-33are given similar reference numerals. As with the operation described inFIG.27, the second stack undergoes partial discharge. But at the point at which the air flow of the second stack reaches a maximum, here about 90% as shown at2088d, the air flow of the first stack is not completely shut off, but is instead kept at a very low rate or a trickle, such as about 5% or less (or in some cases, 10% or less), as shown at2089d(thus operating in a “trickle mode”). To compensate for the flow at the first stack, the flow at the second stack is decreased, as can be seen in the drawings. The trickle in the first stack prevents hot spots, because due to the buoyancy of the air, the hot spots will take more flow to be cooled at low flow. As a result, the possibility of thermal runaway may be avoided or reduced. Similarly, in the second 24-hour period, at the point at which the air flow of the first stack reaches a maximum, here about 90%, e.g., 90%, as shown at2088da, the airflow of the second stack is not completely shut off, but is instead kept at a very low rate or a trickle, such as about 5% or less (for example, 5%), as shown at2089da. To compensate for the flow at the second stack, the flow at the first stack is decreased, as can be seen in the drawings. Again, this mode may prevent or reduce the possibility of thermal runaway. Accordingly,2060D illustrates that the control system is configured to maintain a temperature2065dof the output fluid flow according to a specified temperature profile (here, constant). This is accomplished by alternating, in successive discharge periods (2069dd1,2069dd2), between 1) deeply discharging the first stack while discharging the second stack to a first buffer temperature (2085d) that is above the specified temperature, and 2) deeply discharging the second stack while discharging the first stack to a first buffer temperature (2085da) that is above the specified temperature. Furthermore, during discharge period2069dd1, fluid flow is maintained to the first stack in a trickle mode, while during discharge period2069dd2, fluid flow is maintained to the second stack in the trickle mode. FIG.29provides a detailed illustration of a temperature and fluid flow according to the lead-lag implementation, accounting for variations in the delivery temperature to reduce parasitic drag. Again, features common toFIGS.24-33are given similar reference numerals. As can be seen in the drawings, the output temperature may vary within an acceptable range or the industrial application. (In some cases, a “specified temperature profile” may be a constant temperature, but as shown inFIG.29, the specified temperature profile is non-constant.) In this example, the initial constant temperature is 800° C. at2090e. But the temperature is later varied to a lower temperature such as 700° C. at2091e, by adjusting the flow as explained below. As shown, in the first 24-hour cycle (2067e), instead of having the flow through the first stack be 100% of the total flow as inFIGS.24-33, the flow peaks at about 90%, e.g., 90%, of the total flow as indicated by2094E. Further, because the operating temperature is set at 800° C., the necessity of bypass air is reduced from the start as shown at2093e(e.g., bypass air flow begins at approximately 20%, e.g., 20%, inFIG.29as compared to approximately 40%, e.g., 40%, inFIG.28). Additionally, instead of having the flow in the first stack begin from 60% and increase to 100%, the flow here begins from about 75%, e.g., 75%, and increases to about 90%, e.g., 90%. To accommodate for the additional 10% of flow, additional air begins flowing through the second stack earlier than in previous examples. This, in turn, causes the second stack's discharge temperature to cool slightly earlier than previously described. As noted above, the flow through the first stack is maintained at about 10%, e.g., 10%, during the charging phase of the first stack, as indicated by2097e. When the output temperature is varied to about 700° C., e.g., 700° C., at2091e, the discharge temperature of the second stack also approaches about 700° C., e.g., 700° C., at2092e. Because the air flow of the first stack and the second stack are maintained at a relatively constant proportion during the charging phase (as indicated by2096eand2097e, respectively), the discharge temperatures of the first and second stack behave in a similar manner as in the above examples. During the latter part of the solar day, the bypass flow is increased at2095ein order to cool the unit; the flow of the first and second stacks both decrease correspondingly. In the second 24-hour cycle (2067ea), the constant temperature of 800° C. is also varied to 700° C. by adjusting the flow, as indicated by2090eaand2091ea. Again, instead of having the flow through the second stack be 100% of the total flow as in the above-described examples, the flow is instead only increased to about 90% of the total flow as indicated by2094ea. Further, because the operating temperature is set at 800° C., the necessity of bypass air begins at a lower amount than in previous examples. Similarly, instead of having the flow in the second stack start from 60% and increase upward to 100%, the flow extends from about 75% to about 90%. To accommodate for the additional 10% of flow, additional air begins flowing through the first stack earlier than in previous examples. The first stack's discharge temperature thus cools slightly earlier than previously described. As noted above, the flow through the second stack is maintained at about 10%, e.g., 10%, during the charging phase of the second stack, as indicated by2097ea. When the output temperature is varied to about 700° C., e.g., 700° C., at2091ea, the discharge temperature of the first stack also approaches about 700° C., e.g., 700° C., at2092ea. Because the air flow of the second stack and the first stack are maintained at a relatively constant proportions (as indicated by2096eaand2097ea, respectively) the discharge temperatures of the first and second stack behave in a similar manner as in the above examples. During the latter part of the solar day, the bypass flow is increased at2095eain order to cool the unit; the flow of the first and second stacks both decrease correspondingly. Accordingly,2060E illustrates that different sets of flow parameters may be used during a discharge period to change a temperature of an output fluid flow having a non-constant temperature profile. Furthermore, the output fluid flow temperature may be maintained during a charging phase by keeping the fluid flows of the first and second stack at a relatively constant proportion. To recap, deep discharging is the discharging of a thermal storage stack to a sufficient degree to reduce local temperature nonuniformities within the stack, and thus reduce, mitigate, or eliminate thermal runaway within the stack (and thus extends its life). In some cases, a period of deep discharging may result in a stack being discharged all the way to some temperature floor—namely, the temperature of the bypass fluid flow (the “bypass temperature”). As has been noted, the bypass flow is a flow of cooler fluid within the thermal storage structure—it may be based, for example, on a fluid flow that enters the thermal storage structure via an inlet valve. Accordingly, deep discharging may in some cases cause a stack to be discharged all the way to the bypass temperature or to a temperature approximately equal to the bypass temperature (say, within 10% of the bypass temperature). But as noted above relative toFIG.24, factors such as the peak temperature and delivery temperature affect the amount that a particular stack may be cooled within a discharge period. Further, it may be the case that any of a range of temperatures for a particular use case may effectuate deep discharge—e.g., deep-discharge temperature region2063r. FIG-I-F is a block diagram2098c1that illustrates a range of temperatures that can be used to define different deep-discharge temperature regions for different situations. As shown, the range of temperature has an upper bound of delivery temperature2065u(here 600° C.), a lower bound of bypass temperature2063lo(200° C.), and a midpoint temperature2098m(400° C.), which is the midpoint between the delivery temperature and the bypass temperature. Another temperature reference is shown,2098mm(300°), which represents a midpoint between the midpoint temperature and the bypass temperature, and thus may be referred to as a quartile temperature. Nine possible temperatures are shown: 500° C. (2098t1), 450° C. (2098t2), 360° C. (2098t3), 325° C. (2098t4), 275° C. (2098t5), 245° C. (2098t6), 215° C. (2098t7), 204° C. (2098t8), and 200° (2098t9). Typically, the deep-discharge temperature region's upper bound will be below the delivery temperature. In the case in which the upper bound were at, say 550° C., all 9 temperatures2098t1-9would be within the deep-discharge temperature region. Alternately, if the deep-discharge temperature region's upper bound were defined to be substantially below the delivery temperature, this might exclude just temperature2098t1from the deep-discharge temperature region. Substantially below means at least 20% below, and in other cases could be defined to be 25%, below 30% below, 35%, 40%, 45%, and so on. Temperature2098t2is thus 25% below delivery temperature and could be included in the deep-discharge temperature region depending on how the range is defined relative to the delivery temperature. Note that the lower bound of the deep-discharge region can be set to the bypass temperature or some higher temperature as desired. Another way of defining the deep-discharge temperature region is that the upper end of the deep-discharge temperature region is closer to the bypass temperature than to the delivery temperature, and the lower end of the deep-discharge temperature region is the bypass temperature. Referring to chart2098c1, this would mean that the upper bound would be at midpoint temperature2098m(400° C.) (and for purposes of this example, the upper bound could include midpoint temperature2098m). This definition of the deep-discharge temperature region would include temperatures2098t3-2098t9, and exclude temperatures2098t1-2098t2. Still another way of defining the deep-discharge temperature region is that the upper end of the deep-discharge temperature region is closer to the bypass temperature than to the midpoint temperature, and the lower end of the deep-discharge temperature region is the bypass temperature. Referring to chart2098c1, this would mean that the upper bound would be at quartile temperature2098mm(300° C.) (and for purposes of this example, the upper bound could include quartile temperature2098mm). This definition would include temperatures2098t5-2098t9, and exclude temperatures2098t1-2098t4. Still further, an upper bound of the deep-discharge temperature region could be defined as those temperatures that are approximately equal to the bypass temperature. Thus, with “approximately equal” meaning within 10% of the bypass temperature, this would include temperatures between 200 and 220° C., encompassing2098t7-2098t9. Yet another way of defining the deep-discharge temperature region is to define an absolute temperature range measured up from the bypass temperature. Several ranges of this sort are shown inFIG.33. Range2098r1encompasses the bypass temperature2063up to temperatures 25° C. warmer. Thus, if the bypass temperature were 200° C., range2098r1would include 200° C., 225° C., and all temperatures in between. Similarly, range2098r2encompasses temperatures up to 50° C. warmer than the bypass temperature. Ranges2098r3-r6encompass temperatures up to 75° C., 100° C., 150° C., and 200° C. above the bypass temperature. In a similar manner, although not shown, the upper bound of the deep-discharge temperature may also be defined by establishing a temperature distance measured down from the delivery temperature. For example, a first range might have an upper bound of the delivery temperature minus 100° C. and a lower bound of the bypass temperature. A second such range might have an upper bound of the delivery temperature minus 125° C. and a lower bound of the bypass temperature. A third such range might have an upper bound of the delivery temperature minus 150° C. and a lower bound of the bypass temperature. A fourth such range might have an upper bound of the delivery temperature minus 175° C. and a lower bound of the bypass temperature. A fifth such range might have an upper bound of the delivery temperature minus 200° C. and a lower bound of the bypass temperature. Other ranges are possible, such as a sixth range in which the upper bound of the deep-discharge temperature region is the 300° C. below the delivery temperature. FIGS.24through33have described implementations in which each of two thermal storage arrays are deeply discharged every other discharge period. But this disclosure is not limited to the two-thermal-storage-array implementation. First of all, deep discharging may be performed when only a single thermal storage array is used. In such a configuration, the outlet temperature of the single thermal storage array is allowed to drop to a deep-discharge temperature region on a periodic basis or on an as-needed basis. In configurations with three or more groups, deep discharging may be performed less frequently. The preceding Figures have described implementations in which each of two thermal storage arrays are deeply discharged every other discharge period. But this disclosure is not limited to the two-thermal-storage-array implementation. First of all, deep discharging may be performed when only a single thermal storage array is used. In such a configuration, the outlet temperature of the single thermal storage array is allowed to drop to a deep-discharge temperature region periodically—either at regular intervals or on an as-needed basis. In configurations with three or more groups, deep discharging may be performed less frequently. FIG.30is a block diagram illustrating definition of a deep-discharge temperature based its relative closeness to two reference temperatures.FIG.31is a block diagram illustrating definition of a deep-discharge temperature based on a difference from the bypass temperature.FIG.32is a table illustrating an example in which each of N storage arrays (N=3) is deep-discharged once during every N discharge periods.FIG.33is a table illustrating an example in which each of N storage arrays is deep-discharged multiple times and partially discharged once during every N discharge periods. Consider a configuration with N storage arrays.FIG.30illustrates an example2099t1in which each of the N thermal storage arrays2099ais deep-discharged once during every N discharge periods (2099dp). As shown, N=3 and the three arrays are referred to arrays 1, 2, and 3. In discharge period 1, array 1 acts in a leading mode and array 2 acts in a lagging mode. Accordingly, array 1 is deeply discharged and array 2 is partially discharged. In a discharge period 2, array 2 acts in a leading mode (and thus is deeply discharged) and array 3 act sin a lagging mode (and is thus partially discharged) (2099p). Finally, in discharge period 3, array 3 acts in leading mode (deeply discharged) and array 1 acts in a lagging mode (partially discharged). Thus, two of the three stacks may discharge on a given day, while the other stack does not deep discharge on that day. However, this arrangement may be varied. Thus, in one generalization of a thermal energy storage system with some number N thermal storage assemblages, one possible implementation is that each of the N assemblages (2099a) is deeply discharged once (2099e) every N discharge periods (2099dp). Consider another embodiment illustrated by table2099t2, in which N=3 and again involves arrays 1, 2, and 3 (2099a). At the end of a period of VRE availability (e.g. The end of daytime for solar-charged systems), arrays 1 and 2 may complete the day fully charged; full heat is applied, properly by zone, without significant gas flowing through their conduits. Array 3, however, is operated in a discharging mode with high gas flow in its conduits during charging. Suppose that after charging stops, discharge period 1 begins, and array 3 begins to discharge to provide output fluid flow. During the discharge period, lower-temperature discharge fluid from array 3 is mixed with higher-temperature fluid of array 1 to deliver the output fluid flow. Array 3 deeply discharges by cooling to a temperature that is close to the return gas temperature. Then, when the discharge fluid temperature of array 1 begins to decrease, significant flow through array 3 is terminated, and flow through array 2 is initiated. Mixing of lower-temperature fluid from array 1 with higher-temperature fluid from array 2 also allows array 1 to deeply discharge. In this example, near the end of the discharge period, flow from array 1 is terminated, leaving only array 2 in operation. Thus, array 3 and array 1 both deeply discharge during discharge period 1, with array 2 partially discharging. During the next cycle of discharging and charging, the operation of the arrays is rotated—thus, during discharge period 2, array 2 discharges first, followed by array 3, and then array 1. Arrays 2 and 3, but not array 1, are deeply discharged as a result. Similarly, during discharge period 3, array 1 discharges first, its high-temperature energy being mixed with other array discharges. As array 1 reaches its minimum usable outlet temperature, array 2 begins to add higher-temperature gas, until by the end of the discharge period, arrays 1 and 2 are deeply discharged and array 3 has a temperature profile similar to conduit2010at point in time2051inFIG.23. This approach allows each thermal storage array to be deeply discharged two out of every three charging cycles. The above-described processes have various advantages. For example, in the two-array implementation for a solar use case, each stack is deeply discharged every other day by flow control of the two stacks and a bypass; accordingly, variations in temperature that would otherwise arise from nonuniform heating or cooling in the stack and cause thermal runaway problems are avoided. Deeply discharging a stack causes it to thermally reset such that any nonuniformities that would otherwise cause thermal runaway are avoided or reduced. Further, parasitic drag may be avoided by use of a blended output temperature. While the foregoing aspects are disclosed in the context of a thermal storage array having an internal resistive heating element to provide radiant heat transfer, the present disclosure is not limited to this configuration. For example, the lead-lag approach of having stacks operating in tandem with one stack in the lead mode and the other stack in the lag mode is also applicable in scenarios in which heat is externally delivered by gas. In various implementations, the control system is configured to provide one or more control signals to control various aspects of the thermal energy storage system, including the louvers, the bypass valve and the fan or blower associated with the circulation of fluid through the thermal storage arrays. Additionally, instead of using a single blower for all thermal storage arrays, separate blowers may be provided for each of the airflows, such as the flow of air to the first stack, the flow of air to the second stack, etc. In such an alternative, the control system would control the blowers instead of controlling louvers. In other implementations, however, a combination of blowers and louvers may be used together to control the flow of air through the first stack, the second stack, and bypass to implement the lead-lag paradigm. Operations Associated with System The safe and effective start-up of an OTSG and steam network involves several challenges. All equipment must be brought to operating temperature safely, without discharging sub-temperature fluid, including water, into the system outlet, as such discharges can cause substantial “steam hammer” damage and safety risks. The present innovation addresses these matters to provide a safe, efficient start-up for an OTSG whose heat source is a thermal energy storage unit.FIGS.35(A)-(B) illustrate an example flow2200of startup and shutdown sequences for the thermal energy storage system as described herein. This example flow shows the startup and shutdown of steam generation. While the operations associated with the startup and shutdown sequences are shown in a numerical order, in some cases the order of the operations may be modified, and some operations may overlap or be done concurrently instead of in sequential order. At2201, the outlet valve is in a closed position, or is set to a closed position. As explained above, sensors and communication devices associated with the control system may sense the position of the outlet valve, and if the outlet valve is not in the closed position, the control system may send a signal to the outlet valve, such that the outlet valve is transited to the closed position. At2203, the blowdown valve is opened. In a manner similar to that explained above with respect to2201, the blowdown valve may be moved to the open position, if not already in the open position. A blowdown valve allows release of water and/or steam whose temperature or quality is below the temperature and/or quality required, without introducing the requirement of recirculation of fluid within the OTSG system. At2205, operation of a water pump is started, and low water flow is established. The conduits of the steam generator are now receiving water in liquid form. At2207, the operation of the fan associated with the thermal storage structure is started. For example, the fan may be the blower as explained above. Accordingly, a low hot air flow is established. Heat is thus introduced to the tubes. The previous establishment of water flow within the tubes prevents thermal damage. At2209, as the low hot air flows, and the low water flow is established through the steam generator, the water is heated, and steam starts to form from the heated water, as the water changes phase from liquid to gaseous form. At2211, as the hot air continues to flow and the heating of the steam generator continues, the pressure of the steam increases, and the vapor fraction or quality of the output steam rises. At2213, once the quality of the steam is above a threshold, such as 40%, the outlet of the steam generator opens and the blowdown valve closes. At this point, the steam may be output to the industrial application without the risk of introducing water or sub-quality steam into the application network. At2215, as the outlet opens and the steam generator continues to provide steam, the quality and flow of the steam rise to the required level for the industrial application associated with the output. This increase in flow rate may be at a rate chosen so as to allow the rate of change of other steam generators serving the same industrial load to reduce their flow rates proportionally; or at a rate chosen to match the declining steam production rate associated with shutting down a fuel-fired heater; or at another rate. In some implementations, as steam or heat output from a thermal storage unit begins, a controller reduces the steam or heat output of one or more fuel-fired heaters (boilers, OTSGs, HRSGs, furnaces) which serve the same industrial process load, in such a manner as to maintain an approximately constant total steam supply to the industrial load. Additionally, with respect to the shutdown sequence, at2202, the fan transits from the on state to the off state. For example, the air blower may stop its operation. At2204, the water pump slows or reduces the flow of liquid water to the conduits of the steam generator. At2206, as the flow of heat slows, and the flow of water slows, the quality of steam drops. For example, the quality of steam may drop to a lower quality level, such as 50% or 60%. At2208, once the quality of steam has dropped below a prescribed level, the outlet valve returns to the closed position. Thus, the industrial application is no longer receiving steam, as the quality of steam has dropped below the necessary level for the industrial application. At2210, the water pump pumps water into the tubing so that the tubing or conduit of the outlet is completely filled with water. At2212, the natural circulation of air within the thermal storage structure continues to maintain the dynamic cooling associated with the outer wall invalidation, as explained above. Advantages The example implementations may have various advantages. For example, as explained above, there is a dynamic insulation approach, which provides passive cooling of the thermal storage structure. The incoming cool air absorbs the heat on the outside of the insulation layer, and is eventually passed into the lower portions of the stacks of bricks. As a result, the heat is not transferred to the outer surface of the thermal storage structure. The thermal storage structure can thus house equipment having a wider temperature tolerance. Further, there is lower risk of equipment damage, wear and tear, system failure, injury to the personnel, or other safety issue associated with the presence of heat at the surface of the outer container. Further, the present disclosure contemplated the use of recirculated air to provide cooling for the thermal storage structure, thus eliminating or reducing the need for a secondary cooling system. During shutdown periods, passive buoyancy-induced flow continues so as to provide foundation cooling without backup power or special equipment. This provides an advantage over thermal energy storage systems using molten salt which require active cooling of the foundations of the molten salt tanks, provided by blowers that add to cost and to parasitic electric power consumption and require redundant diesel generator backups. By cooling the foundation as described in this disclosure, energy that was otherwise lost in prior systems is captured as useful energy, and thermal safety in all conditions is provided. Additionally, there is an environmental benefit over previous approaches. Because the control system allows the thermal energy storage system to use the source electricity based on the daily supply and demand of energy, the source electricity that is produced when the supply exceeds the demand can be used for storage during the charging mode. When the demand exceeds the supply, the thermal energy storage system can discharge and provide electricity or outputs for other industrial applications to support the additional demand. This paradigm desirably reduces the need to use nonrenewable energy. Further, various industrial applications such as calcining, carbon capture and others may be performed using heat derived from renewable energy sources rather than nonrenewable sources. As a result, the generation of carbon dioxide or other greenhouse gases may be reduced. In terms of efficiency and cost, the various implementations described in the present disclosure provide a more efficient approach to managing energy input and output.FIGS.34(A)-(C) illustrate various energy input and output curves2100associated with solar energy generation. In chart2101, an example energy input and output graph over a daily period is shown. Curve2105shows the available power. For example, during the time of day when solar energy is available, such as between 4 AM and 8 PM, the available power is illustrated as2105. At2103, the available charging power is shown. As can be seen at2107, the available charging power may reflect the power available. At2103, steam delivery is shown, which reflects the energy that is output or produced. At2109, the actual electricity generated to the customer by the solar energy is shown. Charts2111and2121compare daily power profiles for different seasons. Chart2111illustrates a power profile during a winter day, while chart2121illustrates a power profile during a summer day. At points2115and2117, it can be seen that on a winter day, the power available very roughly corresponds to the charging power. At2125and2127, it can be seen that for a portion of the day the power available corresponds to the charging power, but during the afternoon of the summer day, the charging power is substantially lower than the available power. As explained above, the “day” is defined as a diurnal solar cycle that begins with the time of sunrise and ends with the time of sunset; it is understood that the time of sunrise and sunset can vary depending on physical location in terms of latitude and longitude, geography in terms of terrain, date, and season. At2119and2129, the actual electricity generated to the customer by the solar energy is shown. At2113and2123, steam delivery is shown, which reflects the energy that is output or produced. At2131and2141, a comparison is provided, for a summer day, of non-deferred charging at2131, and deferred charging at2141, such as associated with the example implementations. The elements of2131roughly correspond to the elements of2121and2101. By comparison, at2141, with deferred charging, it can be seen that the charging power2147can very roughly match the power available on a summer day during the afternoon periods. Thus, the example implementations can use deferred charging to use the available power more efficiently. The lifetime of the system components and the efficiency of energy storage may benefit from maintaining the storage core at a lower temperature; however, doing so reduces the amount of energy storage capacity. A thermal energy storage system in which the electrical heaters are embedded within the storage media core causes the heaters to remain at the media temperature over extended periods; and the long-term temperature exposure of the heaters is a key factor in their operating life. An innovation presented here contributes to extended heater and equipment life, by mitigating the annual average temperature that heaters experience. In the case where the storage unit is operated to provide a continuous supply of heat from a variable source, a controller may choose a state of charge below “full charge” on a daily basis, based on forecast energy availability and planned energy demand. For example, in a system powered by solar energy, summer days are longer, so a smaller number of hours of stored energy are required; hence in midsummer the storage unit may be operated by a controller to remain at a lower temperature (or “partial charge”) so as to extend system life and reduce thermal losses, without any reduction in energy delivered to system output. And, for example, in a system powered by solar energy, winter days have lower total energy available, so that the entire energy produced by an associated solar facility can be stored using only a portion of the storage capacity. A controller may operate the storage system in these conditions to maintain only partial charge, again so as to extend system life, without any loss of energy delivery at the system output. Various advantages are provided by other features of the overall system, including those relating to the arrangement of thermal storage arrays, as well as the constituent thermal storage blocks. Those features are the subject of the next Section. Additionally, the present example implementations mitigate thermal stress effects in several ways. The present disclosure mitigates thermal stress arising from thermal expansion due to rapid heating and cooling by partitioning the storage media into bricks of a size and shape which enables rapid radiative heat transfer while maintaining thermal stress levels and patterns within the bricks below levels which induce prompt or gradual failures. Heat transfer flow conduits and flow rates are arranged such that turbulent flow of heat transfer gas provides relatively uniform cooling across the entire exposed heat transfer surface. The storage media bricks are arranged in an array that allows relative movement to accommodate expansion and contraction by individual elements. Also, the array is arranged such that cycles of thermal expansion align the elements of the array to preserve the integrity of the array structure, the integrity of the heating element conduits, and the integrity of the heat transfer gas conduits. In some example implementations, individual bricks are designed such that their center of mass is close to a heating element, and an expanded surface area allows high contact with flowing air. II. Heat Transport in TSU: Bricks and Heating Elements A. Problems Solved by One or More Disclosed Embodiments Traditional approaches to the formation of energy storage cells may have various problems and disadvantages. For example, traditional approaches may not provide for uniform heating of the thermal energy storage cells. Instead, they may use structures that create uneven heating, such as hot spots and cold spots. Non-uniform heating may reduce the efficiency of an energy storage system, lead to earlier equipment failure, cause safety problems, etc. Further, traditional approaches may suffer from wear and tear on thermal energy storage cells. For example, stresses such as mechanical and thermal stress may cause deterioration of performance, as well as destabilization of the material, such as cracking of the bricks. B. Example Solutions Disclosed Herein In some implementations, thermal storage blocks (e.g., bricks) have various features that facilitate more even distribution. As one example, blocks may be formed and positioned to define fluid flow pathways with chambers that are open to heating elements to receive radiative energy. Therefore, a given fluid flow pathway (e.g., oriented vertically from the top to bottom of a stack) may include two types of openings: radiation chambers that are open to a channel for a heating element and fluid flow openings (e.g., fluid flow slots) that are not open to the channel. The radiation chambers may receive infrared radiation from heater elements, which, in conjunction with conductive heating by the heater elements may provide more uniform heating of an assemblage of thermal storage blocks, relative to traditional implementations. The fluid flow openings may receive a small amount of radiative energy indirectly via the chambers, but are not directly open to the heating element. The stack of bricks may be used alone or in combination with other stacks of bricks to form the thermal storage unit, and one or more thermal storage units may be used together in the thermal energy storage system. As the fluid blower circulates the fluid through the structure during charge and discharge as explained above, a thermocline may be formed in a substantially vertical direction. Further, the fluid movement system may direct relatively cooler fluid for insulative purposes, e.g., along the insulated walls and roof of the structure. Finally, a venting system may allow for controlled cooling for maintenance or in the event of power loss, water loss, blower failure, etc., which may advantageously improve safety relative to traditional techniques. The present teaching is an advance in exploiting the physics of heat transfer to enable the cost-effective construction of thermal energy storage systems. Compared to prior art using solid media, designs according to the present disclosure reduce reliance on and improve the reliability of conductive heat transfer; deliver uniform high-temperature heat via convective heat transfer; and principally exploit direct radiative heat transfer, with heat radiating from a heating element and reradiating from heated storage materials (“radiation echoes”) to heat other storage materials rapidly and uniformly. All objects in the universe emit thermal radiation at a rate proportional to their absolute temperature to the fourth power. Specifically, per the Stefan—Boltzmann law, the total energy radiated per unit surface area of a black body per unit time is proportional to the fourth power of the black body's thermodynamic temperature (in kelvin). Accordingly, small differences in temperature cause large differences in the rate of thermal radiation. All objects in the universe also absorb thermal radiation. For any two surfaces exposed only to each other, and absent any incoming or outgoing heat, the differences in temperature between such objects exposed to each other rapidly reduce until the objects are at the same temperature, and thus in radiation equilibrium. It is desirable for a system based upon electrical heating elements that heat solid media to operate heaters at a relatively high power loading—that is, to operate with high wattage per square cm of surface area. Doing so reduces the amount of heating material and cost per unit of charging energy (cost per kW). However, heating element life varies inversely with temperature, so in order to maximize power loading while keeping heating element temperatures as low as practicable, it is accordingly desirable for heaters to radiatively expose materials of the lowest and most uniform surface temperatures possible. In some existing designs, e.g. residential “storage heaters” and Stack disclose designs, heaters are exposed to only a relatively small surface area, for instance by being embedded in channels. Prior art based on Stack's teachings and related designs can be expected to suffer greatly from any nonuniformity in brick size, internal structure, or material composition, since the only means by which surface temperature is controlled is by internal conduction of heat away from the outer surface into the inner material. Variations in aggregate content within the brick itself can contribute to varying thermal conductivity. Such variations in heat conduction will necessarily result in variations in surface temperature if incoming radiation is heating the surface, and such variations will be significant if thermal radiation is unable to carry away higher-temperature energy to lower-temperature regions. More significantly, any cracks formed within a brick can cause great reduction the thermal conductivity across the crack, and consequently if the brick is being radiatively heated this will reduce heat conduction away from the surface, and thus cause regions of higher surface temperature unless thermal radiation can carry away such energy. A design based on, e.g., the Stack design would experience large increases in surface temperature in both these cases, as only relatively small, local surface areas are in radiation communication due to the “channel” design concept. Mitigating these problems incurs costs. Because brick with higher thermal conductivity is more expensive than brick with lower thermal conductivity, and because electrical heating elements are expensive, previous teachings have had serious limitations in practically achievable temperatures and challenges in material usage (heater material usage per kW) and per kWh (storage material usage per kWh), due to requiring average temperatures be low enough to accommodate such local variations. Such previous designs are vulnerable to in-field failures arising from brick cracking contributing to heater failures. Any such crack formation would require reducing or ceasing the powering of heaters in the zone with cracking—as replacement heaters installed at that location would continue to experience such abnormal temperatures—and/or disassembly of the TSU and replacement of cracked bricks, both of which are quite impractical from a cost point of view. In consequence, units of such design would be vulnerable to degradation in their usable storage capacity and charging rate. It is also desirable for systems that heat solid media to avoid high temperature gradients within the solid media, as differential expansion based on temperature results in stresses that may cause cracking or degradation of the media as it successively heats and cools during charging and discharging operations, with resulting large time-varying stress patterns. In designs in which heaters are exposed to only a relatively small surface area, only a relatively small fraction of the bulk material is heated by radiation, and a large proportion of the heating is accomplished via heat conduction within the material. As conductive heating is proportional to AT within the material, per Newton's law of cooling, the rapid heating required in VRE-charged storage media creates significant potential for such systems to experience degradation and cracking from thermally induced stresses. In this sense, a desired property for heater designs—high wattage per unit of surface area—is intrinsically in conflict with a desired property for brick designs—low wattage per surface area—when heaters are installed in channels or narrow passages such as taught by Stack and “storage heaters”. It is further desirable for systems that deliver high-temperature heat from solid media to achieve “thermocline” conditions during discharge, in which portions of the media are cooled to much lower temperatures—releasing more energy per kg of material—than other portions, which remain at high temperatures—thus allowing the delivery of relatively high continuous outlet temperatures throughout an extended period of discharging while the bulk of the storage media swings across a large change in temperature (AT). In service of this goal, convective heat transfer by flowing air which is heated effectively and comes into balance with local media temperature as it flows through successive regions of material is advantageous. An example of such effective thermocline design is the Cowper stove, which incorporates a plurality of long narrow vertical air passages within a brick array, inducing turbulent airflow within the passages and thus effective heat transfer between air and adjacent brick in each zone as air proceeds through the material. Provisions that prevent the transfer of heat via radiation from relatively hotter zones to cooler zones are desirable, as such downward vertical radiative heat flow would decrease the temperature differential between the bottom and the top of the thermocline, reducing its effectiveness and thus lowering the available stored energy per unit of material. The Cowper stove's narrow air passages limit the mutual radiative exposure of surfaces in the vertical axis (due to cos 0), and thus the Cowper stove design satisfies both these criteria for effective thermocline design. However, the Cowper stove design contains a liability. The air passages in Cowper stoves are comprised of many bricks stacked vertically within the unit, each of which has a plurality of passages which must be properly aligned with their corresponding passages in bricks above and below during assembly. Any misalignment during assembly, or due to cyclic thermal expansion and contraction during operation, causes blocking of flow through the passages. Any cracking or spalling of brick, or any introduction of foreign material that introduces material within a passage at any point causes the blockage of flow in the entire passage. In a Cowper stove design, in which the system is heated and cooled convectively, this causes a partial loss of heat storage capacity, as such region is neither effectively cooled nor effectively heated. However, in an electrically radiant heated energy storage unit, such blockages of airflow have greater consequence, as they cause large reductions in cooling during discharge, but no reductions in incoming thermal radiation from heaters. Accordingly, passage blocking can cause larger consequences in electrically heated energy storage units, because as discussed above, variations in unit temperature can contribute to premature heater or brick failures, and in consequence an entire unit may have to be operated at a lower temperature so that the peak temperatures associated with the nonuniformity do not exceed safe material operating temperatures. Some designs, e.g. Siemens ETES, incorporate unstructured media with randomly distributed air passages, causing zones of higher and lower temperature air to mix, and allowing low-temperature air to bypass regions of high temperature solids without being heated, thus reducing thermocline effectiveness and increasing the amount of solid media required to deliver a given amount of thermal energy while maintaining a target outlet temperature, increasing storage media usage per kWh. Designs according to the present disclosure combine several key innovations, which together address these challenges and enable a cost-effective, safe, reliable high-temperature thermal energy storage system to be built and operated. A carefully structured solid media system according to the present teaching incorporates structured airflow passages which accomplish effective thermocline discharge; repeated mixing chambers along the direction of air flow which mitigate the thermal effects of any localized air channel blockages or nonuniformities; effective shielding of thermal radiation from propagating in the vertical direction; and a radiation chamber structure which uniformly and rapidly heats brick material with high heater power loading, low and uniform exposed surface temperature, and long-distance heat transfer within the storage media array via multi-step thermal radiation. Innovative structures according to the present disclosure may comprise an array of bricks that form chambers. The bricks have structured air passages, such that in the vertical direction air flows upwards in a succession of open chambers and small air passages. In some embodiments, the array of bricks with internal air passages is organized in a structure such that the outer surface of each brick within the TSU core forms a wall of a chamber in which it is exposed to radiation from other brick surfaces, as well as radiation originating from an electrical heater. The chamber structure is created by alternating brick materials into a checkerboard-type pattern, in which each brick is surrounded on all sides by open chambers, and each open chamber has adjacent bricks as its walls. In addition, horizontal parallel passages are provided that pass through multiple chambers. Electrical heating elements that extend horizontally through the array are installed in these passages. An individual heating element it may be exposed along its length to the interior spaces of multiple chambers. Each brick within such a checkerboard structure is exposed to open chambers on all sides. Accordingly, during charging, radiant energy from multiple heating elements heats all outer surfaces of each brick, contributing to the rapid and even heating of the brick, and reducing reliance on conductive heat transfer within the brick by limiting the internal dimensions of the brick. Such a chamber structure further provides that a first portion of the heat that emanates from an electric heating element is absorbed by a given first brick surface and further transferred by conductive heat transfer within the brick, thus heating that brick; and another portion of the heat is absorbed by a second brick surface relatively closer to the heater than the first brick surface, raising the temperature of that second brick surface. Because the second brick surface grows hotter than brick surfaces farther away from the heater the second brick surface radiates heat to those farther brick surfaces due to the temperature differential. This process of radiation absorption of bricks, leading to temperature rise, and thence leading to increased thermal radiation, is referred herein as “reradiation.” The reradiation of thermal energy throughout the brick stacks is an important factor in the rapid, even heating of bricks. The structure is arranged such that heating elements are radiatively exposed to passages that extend in a horizontal direction, achieving relatively uniform heating across a given horizontal layer tier of bricks, while inhibiting radiative heating from the heating elements in a vertical direction, thus achieving and allowing persistent of an advantageous vertical thermocline. The radiation chamber structure provides a key advance in the design and production of effective thermal energy storage systems that are charged by electrical energy. The large surface area, which is radiatively exposed to heaters, causes the average temperature of the large surface to determine the radiation balance and thus the surface temperature of the heater. This intrinsic uniformity enables a high wattage per unit area of heater without the potential of localized overheating. And exposed brick surfaces are larger per unit of mass than in prior systems, meaning that incoming wattage per unit area is correspondingly smaller, and consequently thermal stresses due to brick internal temperature differences are lower. And critically, re-radiation of energy—radiation by hotter brick surfaces that is absorbed by cooler brick surfaces—reduces by orders of magnitude the variations in surface temperature, and consequently reduces thermal stresses in brick materials exposed to radiant heat. Thus, the radiation chamber design effectively enables heat to be delivered relatively uniformly to a large horizontally oriented surface area and enables high wattage per unit area of heater with relatively low wattage per unit area of brick. Note that while this configuration is described in terms of “horizontal” and “vertical”, these are not absolute degree or angle restrictions. Advantageous factors include maintaining a thermocline and providing for fluid flow through the stack in a direction that results in convective heat transfer, exiting the stack at a relatively hotter portion of the thermocline. An additional advantageous factor that may be incorporated is to position the stack in a manner that encourages buoyant, hot air to rise through the stack and exit at the hot end of the thermocline; in this case, a stack in which the hot end of the thermocline is at a higher elevation than the cold end of the thermocline is effective, and a vertical thermocline maximizes that effectiveness. By arranging the chambers with a relatively high aspect ratio and predominantly horizontal axis, thermal energy is transferred by multiple steps of reradiation to regions of brick that extend far from the heating element; and as the bulk storage temperature rises, the effect of the ° K{circumflex over ( )}4 (the fourth power of the thermodynamic temperature) thermal radiation drives a very strong “temperature leveling” effect. That is, the hotter the cell becomes, the smaller the differences between the hottest and coolest portions of the cell. As a result, the charging heat transfer within the brick array becomes more effective as temperature rises, and the entire media structure is heated to a uniform temperature with a much smaller total amount of heating element than would be required in a design without a radiative heat transfer structure. This is in sharp contrast to previous teachings, including Siemens and Stack, which can be expected to experience lower heat transfer effectiveness relying on conductive ΔT, which diminishes as bulk storage media temperature rises. An important advantage of this design is that uniformity of heating element temperature is strongly improved in designs according to the present disclosure. Any variations in brick heat conductivity, or any cracks forming in a brick that result in changed heat conductivity, are strongly mitigated by radiation heat transfer away from the location with reduced conductivity. That is, a region reaching a higher temperature than nearby regions due to reduced effectiveness of internal conduction will be out of radiation balance with nearby surfaces, and will as a result be rapidly cooled by radiation to a temperature relatively close to that of surrounding surfaces. As a result, both thermal stresses within solid media, and localized peak heater temperatures, are reduced by a large factor compared to previous teachings. Equally important, the effect of any brick spalling, cracking, or the introduction of foreign materials within air passages is greatly minimized. An individual brick that experiences the blocking of a passage will experience reduced cooling during discharge cycles, and its surface and internal material will remain hotter than adjacent areas, and thus such an area will effectively store less energy, as energy storage is proportional to AT. Because the surface of the brick is in radiative communication with other bricks via the open radiation chamber, radiation will transfer heat from such blocked-passage area to other bricks. Thus, the final AT experienced in a heating-cooling cycle for a design with open radiation cavities will be larger than the AT for any design, such as Cowper stoves or Stack, that does not incorporate this concept. The effect of any brick spalling, cracking, or introduction of foreign materials into an air passage is further minimized due to the flow of air in the vertical axis during discharge. The presence of the radiation chambers eliminates any effect of passage blocking in one brick from affecting flow within the brick above it or below it, since air freely mixes in the chambers between bricks. Similarly, misalignments between bricks in the vertical direction cannot cause air passage blockage, as the narrow air passages in bricks are not in contact, but separated by open chambers. Overview As explained in the foregoing discussion, a system for thermal energy storage is provided that includes an input of electrical energy from a supply, one or more thermal storage units, and a fluid output (which may be or include a gas), such as steam and/or heat, to an application. As explained above, the supply may be an energy source, such as one or more photovoltaic cells. Other energy sources may be employed in combination with or substitution for the photovoltaic cells. The electrical power sources may be any one or a combination of VRE power sources including wind and solar power, less variable renewable sources including hydroelectric and geothermal power, or other power sources including thermal power plants powered by coal, oil, gas nuclear, or any other method of electrical power generation that might be apparent to a person of ordinary skill in the art. The thermal storage units may each include one or more heating elements (e.g., resistive heating elements) controlled by switches that manage and enable the heating elements to receive the electrical energy from the input, and an energy storage structure such as a brick. A fluid movement system, (e.g., one or more blowers that may be oriented to push fluid unto the system or pull fluid from the system) directs fluid through fluid flow paths in the thermal storage units. The energy storage structure includes tiers of thermal storage blocks. For example, a first tier of thermal storage bricks may be arranged in an alternating pattern, such that a gap is formed between adjacent or neighboring bricks. A second tier of bricks is positioned adjacent to the first tier, also in an alternating pattern with a gap formed between adjacent or neighboring bricks. The first tier of bricks and the second tier of bricks are positioned with respect to one another such that the gaps of the first tier bricks are adjacent to the second tier bricks, and the gaps of the second tier bricks are adjacent to the first tier bricks. One or more of the first-tier bricks in the second-tier bricks may have airflow channels formed therein. More specifically, the airflow channels may be formed as apertures, holes, conduits or slots. For example, the airflow channels may be formed as an elongate slot, with a longer dimension being nonparallel to a surface of each brick that is adjacent to a gap. In some implementations it may be advantageous for the air channels to have their longer dimension substantially orthogonal to a surface of each brick that is adjacent to a gap. In other implementations it may be beneficial for the air channels to have their longer dimension substantially parallel to a surface of each brick that is adjacent to a gap. Because the air channels have one axis of short dimension oriented as explained above, turbulent flow may be induced, contributing to effective heat transfer between air and the brick as it passes through the brick. Accordingly, a benefit of the slot arrangement may be a more effective cooling of each brick as air passes through the brick, and consequently a more effective thermocline during discharging. The airflow channels and the gaps between adjacent or neighboring bricks are formed in such a manner as to create airflow paths. More specifically, a first air flow path extends through the airflow channels of a first-tier brick and a second-tier gap adjacent to the first tier brick, and a second air flow path extends through the airflow channels of the second-tier brick and a first tier gap adjacent to the second tier brick. The heater or heating element, which may be a resistive heating element coupled to the input of electrical energy from the supply in a means which includes at least one control switch which may adjust input power to any fraction of the currently available power, is positioned adjacent to the first tier of bricks and the second tier of bricks. For example, the heating element may extend parallel to a longitudinal direction of the tiers of thermal storage bricks. According to one example implementation, the heating element extends laterally in a curvilinear pattern, between rows of the plurality of blocks. According to one example implementation, the second tier may be positioned above the first tier, such that the airflow paths are substantially vertical. However, the example implementations are not limited thereto, and other spatial arrangements between the first tier and the second tier as may be understood by those skilled in the art may be used in substitution or combination with the substantially vertical air flow paths. Further, while the foregoing example implementation discloses a first tier and a second tier, the present example implementation is not limited thereto. For example, one or more additional tiers may be incorporated with the first tier and the second tier, to form additional alternating patterns having gaps and airflow channels. Further, the bricks in each of the additional tiers may be positioned to form additional portions of the first and second airflow paths, such that the additional airflow paths extend through airflow channels of a brick, and through a gap of a tier adjacent, such as above or below, the brick. In the foregoing multiple tiers of bricks, the dimensions of the bricks may be varied, such that the tiers at or closer to an upper portion of the stack may be larger in at least one dimension, such as height, as compared with bricks at or closer to a lower portion of the stack. By having such variation in the dimensions of the bricks, brick size may be optimized to account for greater weight loads near the lower portion of the stack, and/or higher air temperatures closer to the upper portion of the stack. Example, bricks in the upper layers may be taller than the bricks in the lower layers. The reason for this is because as gas is constantly flowing in at the bottom of the stack and cooling the lower levels, more heat power is needed per unit mass to heat the bricks near the bottom of the stack. More specifically, the heat from the heating element is not only heating up the brick itself, but also heating the gas within the volume of the brick up to a desired temperature. Moving vertically toward the upper portion of the staff, the same heater may heat larger bricks, because the bricks do not have the same incoming air that needs to the heated as the bricks near the bottom of the stack. Moreover, the heaters have a certain amount of power that they are capable of outputting, such that the heaters at the upper and lower portions of the stack may have a heater with similar or same power output. Thus, the cavities may be taller towards the upper portion of the stack, because the entering air has already been heated by the bricks at the lower portion of the stack, and the energy from the heating elements is heating up the mass of the brick itself, as opposed to the air within the volume of the mass of the brick. In some implementations, a control system for the heater elements is configured to power heater elements at one or more different levels independently, e.g., to output more or less energy depending on the height (e.g., tier) of the heater elements in the assemblage. Multiple stacks of bricks may be arranged adjacent to one another to form a thermal storage unit. Similarly, multiple thermal storage units may be arranged adjacent to one another to form the thermal energy storage system. Example implementations may also provide an efficient and reliable thermal storage system that involves use of multiple thermally conductive and absorbing bricks being stacked together to form thermal energy storage cells having sizes and material compositions chosen to mitigate thermal stresses. The thermal storage system may also maintain a constant temperature profile across the length of the cells (stacked bricks) thereby slowing temperature ramp, and reducing the generation of hot and cold hot spots, mechanical stress, thermal stress, and cracking in the bricks. In some example implementations, the system may include multiple cells to form a thermal unit. The system may include multiple cells, each cell being made of multiple stacks. During charging, a controller may provide power flowing at different rates at different times selectively to individual heating elements or groups of elements so as to control the rate of heating of specific subsections of stacks, or specific stacks within the unit, or specific sections (e.g., specific bricks or sections of bricks within a stack. For example, if only 60% of maximum energy capacity is anticipated during a specific charging cycle, only elements in 60% of stacks or in 60% of bricks in the system may be heated. The selective heating of specific heating elements may ensure that 60% of bricks achieve maximum temperature during the charging period, instead of heating all of the elements causing 100% of bricks being heated to 60% of maximum temperature. Such a charging configuration may have various benefits and advantages. For example, the efficiency discharge of energy during a discharging operation may be substantially increased. The system may include one or more air blowing units including any combination of fans and, blowers, and configured at predefined positions in the housing to facilitate the controlled flow of air between a combination of the first section, the second section, and the outside environment. The first section may be isolated from the second section by a thermal barrier. The air blowing units may facilitate the flow of air through at least one of the channels of the bricks from the bottom end of the cells to the upper end of the cells in the first section at the predefined flow rate, and then into the second section, such that the air passing through the bricks and/or heating elements of the cells at the predefined flow rate may be heated to a second predefined temperature, and may absorb and transfer the thermal energy emitted by the heating elements and/or stored by the bricks within the second section. The air may flow from the second section across a steam generator or other heat exchanger containing one or more conduits, which carry a fluid, and which, upon receiving the thermal energy from the air having the second predefined temperature, may heat the fluid flowing through the conduit to a higher temperature or may convert the fluid into steam. Further, the system may facilitate outflow of the generated steam from the second end of the conduit, to a predefined location for one or more industrial applications. The second predefined temperature of the air may be based on the material being used in conduit, and the required temperature and pressure of the steam. In another implementation, the air leaving the second section may be delivered externally to an industrial process. Additionally, the example implementations described herein disclose a resistive heating element. The resistive heating element may include a resistive wire. The resistive wire may have a cross-section that is substantially round, elongated, flat, or otherwise shaped to admit as heat the energy received from the input of electrical energy. With regard to the composition of the resistive heating element, if the resistive heating element is a resistive wire, it may be metallic. Further, the resistive heating element need not be limited to metallic wire, and may instead be formed from another material, such as a ceramic, including but not limited to silicon carbide, magnesium silicide, or may be formed from a combination of these and/or other materials. Bricks and Stacks Example implementations of the energy storage system include a housing comprising at least two sections (also referred to as cells) which may be fluidically coupled to each other. A first section may include one or more thermally conductive bricks of being stacked together with each other to form a thermal storage cell within the housing. Note that some blocks may be relatively large and include multiple portions (e.g., rectangularly-shaped brick portions). Thus, a given block may include portions on multiple tiers and may cover multiple chambers. A heating element may be suspended from a support within a passage within the array, or may mechanically form part of the array itself (as, for example, a conductive ceramic material formed as one or more bricks within the array), or may be positioned adjacent to the array (as, for example, a heating element such as a tungsten or xenon element encapsulated in a material which is at least partially transparent to electromagnetic radiation in the infrared and visible spectrum). One or more of the bricks may include at least one channel extending longitudinally between two opposite ends of the bricks. Accordingly, at least one of the channels of each of the stacked bricks corresponding to one of the cells are in line with each other. Alternatively, such channels by be arranged such that adjacent bricks channels are arranged together to create a channel. A number of bricks may be stacked over one another to form an assemblage of the required height. The height of the cells may be selected considering the height of the housing. Further, the dimension of the bricks that are stacked over one another may be the same, or it may be different. For example, the bricks and an upper portion of the cell may have a greater height than the bricks at a lower portion of the cell. The system includes at least one heater or heating element disposed within at least one of the channels corresponding to each of the bricks. Each of the heating elements may be electrically connected to one or more electrical power generation sources (also referred to as electrical energy sources), either individually or collectively, and may be configured to receive electrical energy from the electrical power generation sources and generate thermal energy, such that temperature of each of the heating elements reaches to a temperature. The application of electrical power to the heating element may be controlled based on optimal heating conditions configured to reduce thermal stresses in the bricks. Such electrical control may be implemented by switches of various types, including electromechanical contactors and semiconductor devices including thyristor and transistor type devices including insulated-gate bipolar transistors (IGBTs). The control of electrical power to the heating element may be determined by a controller that takes into account values of currently available total energy from a VRE source or other parameters in determining a desired rate of charging. The controller may operate a switch multiple times per second in a control circuit whereby such operation of the switch enables a heater to receive one of many average power levels. The controller may operate a plurality of such switches in a pattern such that an incoming amount of total power is distributed uniformly or nonuniformly across a varying number of heaters whose total power demand (if all operated at full power concurrently) may exceed the incoming available power. For example, electrical energy may be controlled to keep the heating element a fixed temperature above the surrounding bricks to reduce thermal stresses. As the brick temperature increases, more electrical energy may be applied to the heating element to increase the temperature of the heating element to the maximum temperature achievable by the heating element. Therefore, heater elements at different vertical elevations within an assemblage of thermal storage blocks may be operated at different temperatures, as higher blocks will typically have a greater temperature. Further, in some example implementations, the electrical power applied to the heating element may be gradually ramped in during generation to prolong the life of the heating element. The means of this ramping may include a controller commanding external power conversion devices, including solar inverters, to adjust their power delivery, and may include a controller commanding semiconductor switching devices including thyristors and IGBTs to rapidly switch in a time-varying pattern. Additional optimizations of the charging of the system may be achieved by controlling the application of electrical power to the heating element. In an example implementation, bricks may be made of thermally conductive and absorbing materials having a composition and dimensions, such that thermal energy emitted by the corresponding heating elements, upon receiving the electrical energy, may heat each of the bricks and the corresponding cells up to the first predefined temperatures. Further, the cells may be configured within the housing such that there is a predefined gap between adjacent cells, to facilitate the flow of fluid through the cells. Brick Structure and Shape The structure and shape of the bricks is configured to repeatedly heat and cool for the purpose of storing energy. Energy input is provided in the form of electrical energy, which heats wires, filaments, rods, or other solid conductive materials to emit radiant thermal energy. The energy output is in the form of heat delivered in a circulating gas introduced at one portion of the structure, and which leaves another portion of the structure at a higher temperature. The structure includes refractory materials (e.g., bricks), which may be in the form of one or more cast or extruded shapes, and so arranged as to have an alternating sequence, along both vertical and horizontal axes. The structure includes a plurality of open chambers and bricks, with the bricks including air passages having at least one dimension which is much smaller than the other two dimensions. The passages are open to the chambers at its top and bottom surfaces, and are internally exposed to a radiating surface heated by electrical resistance. In the chambers, heat is transferred by thermal radiation from relatively hotter surfaces to relatively cooler surfaces. FIG.36shows views36000of brick and stack structure and shape, a cutaway view36001and an isometric view36003of a chamber36005formed by the surfaces of adjacent bricks36007having channels36009formed as the slots36011. The resistive heater36013provides the heat energy converted from electrical energy. One surface of the chamber36003includes an surface heated to a higher temperature by electrical energy (shown as solid lines with arrows), and other surfaces of the chamber exposed to thermal radiation from all internal surfaces (shown as broken lines with arrows). In more detail, as shown inFIG.37, the structure37000comprised of refractory materials includes an inner chamber having a region directly heated by electric power radiating heat. A region37001receives higher radiative flux from the electric power heating element and is at a higher temperature, and is radiating thermal energy within the chamber that is absorbed by lower temperature surfaces of the chamber37002,37003,37004at different rates based on their angle and distance from the first radiant surface, and which consequently are heated to different temperatures by incoming radiation from region37001. The second surface37002is at a higher temperature than the third surface37003, which radiates thermal energy absorbed by the third surface37003, reducing the temperature difference between them. A fourth surface37004is located farther from an electrical heating element and receives incoming radiation emitted by the electrical heating element, the first surface region37001, and surface regions37002and37003, as well as other surface areas. The system as above, in which the brick materials whose respective surfaces form the walls of the chamber each have internal flow passages37005, which allow air to flow, having at least one dimension that is substantially smaller than other dimensions, which causes the flowing air to have at least partly a turbulence pattern. Additionally, the system incorporates one or more regions below the first heated chamber, with air passages which enable flow upwards into the heated chamber, but so arranged as so block thermal radiation emitted by the heated chamber. Electrical switches (not shown) control the operation of the electrical heaters under the command of a control system (not shown). Further, louvers and/or variable speed fans may control the rate of flow of air upwards within the air passages and chambers.FIG.38is a diagram3300illustrating an example brick3301according to some implementations. The brick3301is formed in a zigzag shape, having an upper surface including a region containing openings3303(which are slots in this example) which extend vertically through the brick3301. Additionally, a seating portion3305is provided, such as that bricks3301may the stacked on top of each other and seated in a manner such that they do not laterally shift with respect to one another. Further, side portions3307,3313in a longitudinal direction may be arranged with other bricks in a manner that creates chambers or cavities within the bricks. These radiative chambers may permit reradiation in various directions, including horizontal reradiation (e.g., charge the brick with radiation at 90 degrees to the vertical axis, such that radiation moves in the horizontal plane). The structure of bricks and stacks may promote the flow of energy in the horizontal plane by giving radiation a free line of sight, or capability to radiatively move energy rapidly in the horizontal plane. This approach may reduce or avoid hot spots. Simultaneously, energy is discharged the vertical axis to the top of the stack. By allowing radiation to move freely in the horizontal plane but not substantially in the vertical axis, the thermocline may be maintained (and vertical reradiation from the point of discharge back down the stack is obstructed, such that the energy flows to the output in an intended manner). The overall shape of the brick3301includes a first section that extends longitudinally in a first direction, a second section that is oriented orthogonally to the first section and extends longitudinally in a second direction, and a third section that extends longitudinally in the first direction. Thus, the brick3301has a zigzag appearance. Each of the sections has the openings3303in a repeated pattern extending along the upper center surface, framed by the seating portion3305along the periphery. The seating portions of the second section and third section are shown as3309and3311, respectively. Additional recesses3315and3317are provided at opposite ends of the first and third sections of the brick3301. In the illustrated implementation, fluid flow slots are elongated in one horizontal direction. As shown, fluid flow slots may be oriented with their longer direction parallel to heater channels and perpendicular to radiation cavities at a given level. FIG.39illustrates a schematic perspective view3500of a brick3501according to another example implementation. While the brick3301shown inFIG.38has a common vertical profile across all of its sections, the brick3501is assembled in a manner such that there are sections of the brick at different vertical profiles. More specifically, the brick3501includes a first portion3501, a second portion3503and a third portion3507. These three portions3501,3503and3507are connected at a junction3511. Recesses3513and3515are provided to house the heating element. As explained above, the openings3509are provided in each of the portions3501,3503and3507. A chamber formed by the bottom surface of the first portion3501, and side surfaces of the second and third portions3503and3507, respectively. Similar seating portions are also formed in the brick3501as explained above. Thus, the bricks3501may be arranged in a stacked structure to form an assemblage, and multiple assemblage may be arranged to form a unit or cells, with a given TSU having one or more units or cells. FIG.40illustrates a schematic perspective view3100of a brick3101according to the above example implementation. The perspective view is positioned to show the features of the brick3101from a side perspective. As explained above, the brick3101includes sections3103,3105and3107that are connected to one another at a junction3111. Slots3109and recesses3113,3115are provided. Similar to the above a seating region is provided adjacent to the slots at the perimeter of the upper surfaces of the sections3103,3105and3107. The chamber formed by the sections3103,3105and3107is directly behind section3103, directly below section3105, and directly to the left of section3107as illustrated. Other bricks3101may be positioned in a stacking or interlocking manner with respect to the brick3101, to form additional sides of the chamber. FIG.41illustrates an isometric view3450of interlocking bricks according to the example implementations. More specifically, bricks3401,3403,3405and3407are arranged so that the seating regions of the bricks are arranged to interface with adjacent bricks. As explained above, this approach allows the bricks to be stacked in a manner that reduces the risk of misalignment or undesirable movement after the installation. At3409, a chamber formed by the interlocking bricks is shown. Thus, the bricks, once interlocked, form the chamber that is substantially enclosed. In some implementations, an assemblage includes bricks oriented differently, e.g., with blocks rotated at different angles, some blocks upside-down, etc. Example Assemblage and TSU Structure FIG.42illustrates an example refractory stack3600according to some implementations. As shown in3601, the bricks may be provided in an interlocking manner, as explained above with respect toFIGS.40and41. Further, the chamber or cavity is formed at3603. Slots or openings3605extend vertically through the bricks. As shown at307, the resistive heating element is provided between some of the bricks. As illustrated, the resistive heating element3607appears as a wire that extends in a repeating curvilinear pattern horizontally with respect to the fluid flow3609of the stack3600. Other configurations of the resistive heating wire3607may be substituted for the configuration illustrated, so long as the resistive heating element3607receives the electrical energy of the source as its input and generates heat energy during a charging mode of the TSU. In some implementations, the blocks are stacked adjacent in vertical tiers such that fluid cannot flow between tiers of blocks in a horizontal direction, but flows only through vertical fluid pathways defined by fluid slots and radiation chambers. This may facilitate controlled, even heating in various implementations. FIG.43shows an isometric view3700of the stacking of the bricks according to an example implementation. As shown herein, bricks3701and3705are stacked with respect to one another to form the radiative chambers3709. A heating element may extend through a space3707(also referred to as a channel) between some of the adjacent bricks. FIG.44illustrates a side cutaway view3800of the stack of bricks according to the example implementation. For example, bricks3801are arranged in an interlocking manner with respect to one another. Some portions of the bricks have openings3803, such as elongated slots that extend vertically through those portions of the bricks. An opening3805is provided between some of the bricks in a repeating pattern, both horizontally and vertically throughout the stack. The resistive heating element, depicted as3807is provided in the openings3805. As the fluid flows vertically as shown at3809, the fluid is heated. Although it is not illustrated in this drawing, the radiative chambers formed by the interlocking bricks, in conjunction with the openings3805, provide for the absorption of heat radiated from the heating elements3807, and further allow for conduction of heat within a block in various direction and reradiation of the heat in various directions. In particular, the heat may be reradiated in a horizontal direction. FIG.45illustrates an isometric view3900of the rows of stacked bricks according to the example implementations. More specifically, some of the bricks3901,3903are interlocked with each other at a first level of the stack, and other portions of those same bricks at3909and3911are inter-locked with one another and a second layer of the stack. Adjacent bricks3913may interlock with some of the bricks in the adjacent row. Other bricks3905may not interlock with some of the bricks in the adjacent row, and may instead be separated by the space in which the heating element is positioned. By forming an interlocking pattern between bricks, the stack may be laterally supported on the sides. For example, separate bricks at3909and3911are spanned by a single brick at3901and3903, to form the interlocking pattern with the underlying bricks. As explained above, an upper surface of the brick has slots in a central portion and a lip at the edge portion. The lip at the edge portion supports the load of another brick that is above the brick. Generally, lips or shelf portions on thermal storage blocks may interlock with other lips/shelves or with other block portions to prevent blocks from shifting laterally relative to one another. For example, in an earthquake, the bricks may not move because they are surrounded with other bricks that are interlocked using the lip structure. The lateral support may result in a more stable structure for the stack. Additionally, the individual bricks may be formed at greater scale, with additional walls, rows, chambers, vertical levels, slots and the like used into a single block structure, such that multiple chambers are formed within the single block structure. The blocks may all be of the same size, or they may be of different sizes. For example, and as explained above, the height of bricks in the lower region of the stack may be less than the height of bricks in the upper region of the stack. By having larger structures, fewer structures are required to form a stack. Similarly, multiple bricks may be fused together prior to stacking, to have the same effect as a brick manufactured as a very large size and scale as a single block. In either case, a potential benefit of having fewer structures to form a stack is the ease of assembly, e.g., in requiring the fitting of less pieces to one another. Further, the approach with larger blocks may also avoid a potential disadvantage of assembling more and smaller bricks, in that the interlocked bricks that are stacked on top of each other may rub against one another during the thermal expansion, thus causing additional wear and tear. The larger bricks have a smaller surface area in contact with other bricks, which may result in less wear and tear. In some implementations, the slots that are adjacent to the heating elements are parallel to the heating elements, while the slots that are above the heating elements are orthogonal to the heating elements. In these implementations, the slots may be perpendicular to a wall from which the energy will be radiatively received. As can be seen in the drawing, a long row of slots is formed above and parallel to the direction of the heating elements. The bricks have slots that are orthogonal to the long rows of slots, and those slots are spaced apart by the radiative chambers. In some implementations, thermal storage blocks may be sized based on thermal conductivity. For example, in some implementations the thermal energy should be radiated into the brick with a certain thermal conductivity, within a certain amount of time, given the thermal mass. If the brick size is too large, the amount of time required for the energy to be radiated into the center portion of the brick may exceed the available time, and the central portion of the brick will not heat up in time for the charge and discharge cycles. On the other hand, if the chamber is dimensioned below a certain width, while the temperature may become more homogeneous, the chamber may become too narrow, which may cause problems with flow or structural integrity. The overall shape of the blocks may also be varied. While the examples shown herein illustrate rectangular volumes with relatively flat walls and interlocking structures with orthogonally position structures formed above or below, the shape is not limited. For example, the bricks may be formed such that the overall shape is trapezoidal or oval instead of rectangular. Further, the wall need not be flat, and may be curved, serpentine or some other profile. Also, as an alternative to having slots in the bricks, the bricks may be configured to be stacked with substantially thinner elements to form gaps between the bricks, and alternating the bricks, to form the gaps as the equivalent of slots, such that the fluid passes between the bricks. Additional Thermal Storage Block Examples FIG.46is a diagram showing an isometric view of an assemblage of thermal storage blocks. In the illustrated example, the storage blocks define channels (e.g., channel4607) in which heater elements are positioned. The channels may include horizontal slits for hanging heater elements. As shown, the blocks define multiple radiation cavities4601and multiple fluid flow slots4603. The cavities and slots are arranged such that a given vertical fluid flow pathway includes alternating cavities and slots, with a cavity positioned above a slot that is in turn positioned above a cavity, and so on, until reaching the top of the assemblage. Thus, a given fluid pathway may include multiple cavities and multiple fluid flow slots, which may alternate. The volume defined by a given cavity is greater than the volume defined by a given fluid flow slot, in this example. In the illustrated example, the blocks also include slots4605positioned above the channels for the heater elements. Fluid flow may also occur via these slots, e.g., due to movement caused by a blower or due to buoyancy of heated fluid. As shown, the heater channels4607are located adjacent to radiation cavities and orthogonal to the vertical direction of fluid flow, which may promote horizontal radiation and energy transfer. The heater elements may also heat the bricks via convection. As shown, in some implementations the size of the radiation cavities is fairly large relative to the size of the block portions that bound the cavities. In some implementations, the area covered in a horizontal plane by a given radiation cavity is at least 40%, 60%, 70%, or 80% of the area of a surface of a portion of a thermal storage block that bounds the radiation cavity (where the area of the surface of the portion of the thermal storage block includes the area of any slots in the portion). The substantial size of the radiation cavities may facilitate even heating via radiated energy. FIG.47is a diagram showing an exploded perspective view of the blocks ofFIG.46. As shown, blocks may have different sizes in a given stack. The blocks may be formed such that multiple blocks define a give radiation cavity or fluid flow slot. The relatively large size of the blocks in the illustrated implementation may reduce wear and tear due to friction forces between blocks caused by slight blocks movements or expansion/compression. Larger blocks may each include multiple radiation cavities and fluid flow slots and may also cover multiple cavities/slots on a lower level. Larger blocks may be manufactured as a whole (e.g., using a correspondingly-sized mold) or in sections and fused together. As shown, a given block may include radiation cavities and fluid flow slots at multiple vertical elevations. Generally, a given block may include multiple portions that each bound multiple radiation cavities and include one or more fluid flow slots. FIG.48is a diagram showing a top-down view of the blocks ofFIG.46, according to some implementations. As shown, the fluid flow pathways are formed by corresponding sets of radiation chambers4601and fluid slots4603. This view also shows the slots4605positioned above and below heater element channels. FIG.49is a diagram showing a top-down view of one or more thermal storage blocks, according to some implementations. In the illustrated example, the block(s) include heater channels49007, heater elements49009positioned in the heater channels, heater slots49005, radiation chambers49001, and fluid flow slots49003. In some implementations, the rounded corners of the radiation chambers may facilitate relatively uniform heating of the blocks. Note that the block(s) ofFIG.49-FIG.51are otherwise mostly similar to the blocks ofFIG.46but with multiple fluid slots49003positioned above a given radiation cavity49001. In these implementations, the stream of fluid passes through the multiple fluid flow slots from a corresponding radiation cavity (and in many cases, from the multiple fluid flow slots into another corresponding radiation cavity of the fluid pathway). This may provide additional structural stability and thermal storage density. Further, the smaller slots may reduce laminar flow in the slots, which may improve energy transfer. FIG.50is an isometric view of the block(s) ofFIG.49andFIG.51is a side view of the block(s) ofFIG.49. Example Stacks and Thermal Storage Unit FIG.52illustrates an isometric view4000of the stack4001of bricks (which may also be referred to as an assemblage) according to an example implementation. More specifically, columns4009of the bricks are provided. In this case, there are six columns. However, the number of columns is not specifically limited, and more or less columns may be formed in a stack. Additionally, the stack has a lower portion4003and an upper portion4005. Bricks at the lower portion4003may have a smaller height as compared with bricks at the upper portion4005of the stack4001. Openings4007for the resistive heating elements are also shown for reference. FIG.53illustrates a side view4100of an example system according to some implementations. An outer structure4101may include a frame that provides seismic protection, as well as an outer surface of the TSU itself. The outer surface of the TSU and the frame need not be built integrally or even connected with one another, but may optionally have such an arrangement. Additionally, a foundation4103is provided at a lower surface of the TSU. A steam generator4105is provided at an output of the TSU, as well as an air blower that is not illustrated. The system may include multiple units4107,4109that are individually controlled for discharge and charge, as explained above. Each of the units4107,4109include stacks of bricks formed in columns4119. The bricks4121may include a passage or opening4123, through which the resistive heating element may pass. At the lower portion of the units4107,4109, the flow of incoming fluid may be controlled by louvers4111and4113, respectively. The louvers may be operated in conjunction with the hot fluid bypass, which is explained above with respect to the overall system. As also explained above, each unit4107,4109is controlled independently, such that the louver4111is open while the louver4113is closed. Similarly, fluid dams or louvers may be provided at the upper portions, as depicted at4115and4117, respectively FIG.54illustrates an isometric view4200of the system, with cutaways showing the system elements, according to the example implementations. More specifically, the structure4201may include the outer frame having seismic protection features, either integrally or separate from the outer surface of the TSU. A foundation4203and the steam generator4205are illustrated as well as the fluid blower4223. Each of the units4207,4209may be separated by one or more brick support structures or walls having insulated properties. Thus, the controller may independently control the charge and discharge of each of the units4207,4209. Further, as explained above louvers4211and4213are provided to control the flow of input pair to the units4207,4209. As shown at4215, the heated fluid is channeled to the steam generator4205. For reference, each of the units4207includes multiple columns4221of stacked bricks4217, including heating elements in a space at4219. FIG.55illustrates an isometric view4300of an outer structure4301of the TSU according to an example implementation. A duct or channel4303is provided to output the hot fluid to the steam generator, which is not shown. The hot fluid is channeled from the stacks of bricks in the units by way of passages4305. FIG.56illustrates another perspective view4400of the thermal energy storage system according to the example implementations. It is understood that the stacks of bricks, units, dynamic insulation, and other structures and features described above are contained in the TSU4401. The output of the TSU4401provides hot fluid to output4403. The hot fluid is received at4405by a steam generator. However, additional structures may be provided such that the hot fluid is sent, either simultaneously or independently, directly to industrial application. Also shown is a water input4407, which may pump water through the conduits of the steam generator4405based on water received as feedback from industrial application, or water from an external source. The fluid blower4409, which provides the cooled fluid that is the byproduct of passing through the steam generator, or reuse in the TSU4401, as circulated either by dynamic insulation or hot fluid bypass, as explained above. FIG.57illustrates an isometric view4500of the thermal energy storage system according to an example implementation. As explained above, the system may be framed with seismic protection features, either separate or integral with the outer structure4501. Between the outer structure4501and an insulation layer4517, there is a fluid gap for dynamic insulation as discussed in detail below, having the flow controlled by louvers4513and4515at the entrance of the stacks. Further, a passage4503receives the heated fluid from the stacks of bricks and the units, and passes the heated fluid to an output, and a duct4505, which provides the heat to be used in industrial applications such as a steam generator or as direct airport other industrial process. The output may be processed at4507at the steam generator. Additionally, at4509, inputs of water and outputs of steam may be provided. The cooled fluid may be recirculated to the TSU by way of the blower4511. Example System with Dynamic Insulation and Failsafe Venting Techniques In some implementations, the system uses dynamic insulation to advantageously improve insulation of a TSU, allow use of less expensive insulation materials, increase equipment life, or some combination thereof. In some implementations, the system uses a stream of fluid that will eventually pass through one or more assemblages of thermal storage blocks to first facilitate passive insulation. In some implementations, the fluid is recycled, e.g., from a steam generator. Further, the system may advantageously use failsafe venting to avoid overheating in certain failure scenarios. The venting may also be used for temperature reduction to allow TSU maintenance. Disclosed dynamic insulation and failsafe venting techniques may be implemented independently (e.g., a system may use dynamic insulation but not failsafe venting or vice versa). In some implementations, however, the two techniques operate in a synergistic manner. For example, the failsafe venting may use the chimney effect to passively draw fluid through passageways through which fluid is normally directed by a blower for dynamic insulation. FIG.58provides an isometric view of another example thermal storage unit, according to some implementations. In the illustrated example, the thermal storage unit5800includes an outside enclosure5801an external vent closure5803, side vents5809, and components5807. In some implementations, various vents may open to cool the unit for maintenance or to safely cool the unit in case of equipment failure. Examples of potential equipment failures include, without limitation: blower failures, power outages, water failures. Various elements utilized for dynamic insulation may also be used for passive cooling by the failsafe mechanism. In some implementations, at least a portion of the steam generator is included within the outer enclosure5801(as shown inFIG.58throughFIG.62and discussed in detail below). Other components5807located outside the outer enclosure may include other steam generator components such as a water pump, valves, an emergency pressure relief valve, etc. In some implementations, the portion of the steam generator in which heated fluid from the thermal storage blocks interacts with water tubes is included in the outer enclosure. In some implementations, this may advantageously allow fluid leaks in certain locations to occur within the outer enclosure, which may mitigate effects of those leaks relative to leaks to an exterior of the outer enclosure. Further, pressure differences within different parts of the unit may also mitigate effects of fluid leaks. Components5807may further include other components that are not part of the steam generator such as electrical components, cooling systems for electrical components, etc. FIG.59provides an isometric view of the thermal storage unit with multiple vents closures open, according to some implementations. Therefore,FIG.59may represent a maintenance or failsafe mode of operation. As shown, the thermal storage unit also includes an inner enclosure5823(shown in more detail inFIG.60). The outer surface of the inner enclosure5823and the inner surface of the outer enclosure define a fluid passageway through which fluid may be conducted actively for dynamic cooling or passively for failsafe operation. The inner enclosure5823includes two vents5815and5817which include corresponding vent closures in some implementations (portions of vent door5813, in this example). In some implementations, vents5815and5817define respective passages between an interior of the inner enclosure5823and an exterior of the inner enclosure. When the external vent closure5803is open, these two vents are exposed to the exterior of the outer enclosure as well. As shown, the vent5815may vent heated fluid from the thermal storage blocks conducted by duct5819. The vent5817may allow entry of exterior fluid into the fluid passageway and eventually into the bottoms of the thermal storage block assemblies via louvers5811(the vent closure5809may remain closed in this situation). In some implementations, the buoyancy of fluid heated by the blocks causes it to exit vent5815and a chimney effect pulls external fluid into the outer enclosure via vent5817. This external fluid may then be directed through louvers5811due to the chimney effect and facilitate cooling of the unit. Speaking generally, a first vent closure may open to output heated fluid and a second vent closure may open to input external fluid for passive venting operation. During passive cooling, the louvers5811may also receive external fluid directly, e.g., when vent closure5809is open. In this situation, both vents5815and5817may output fluid from the inner and outer enclosures. Vent door5813in the illustrated implementation, also closes an input to the steam generator when the vents5815and5817are open. This may prevent damage to steam generator components (such as water tubes) when water is cut off, the blower is not operating, or other failure conditions. The vent5817may communicate with one or more blowers which may allow fluid to passively move through the blowers even when they are not operating. Speaking generally, one or more failsafe vent closure may close one or more passageways to cut off fluid heated by the thermal storage blocks and reduce or avoid equipment damage. When the vent door5813is closed (e.g., as shown inFIG.60), it may define part of the fluid passageway used for dynamic insulation. For example, the fluid movement system may move fluid up along one wall of the inner enclosure, across an outer surface of the vent door5813, across a roof of the inner enclosure, down one or more other sides of the inner enclosure, and into the thermal storage blocks (e.g., via louvers5811). Louvers5811may allow control of fluid flow into assemblages of thermal storage blocks, including independent control of separately-insulated assemblages in some implementations. In the closed position, vent door5813may also define an input pathway for heated fluid to pass from the thermal storage blocks to the duct5819and beneath the vent door5813into the steam generator to generate steam.FIG.61shows a passageway5829that is open when the vent door5813closes vents5815and5817for heated fluid to enter the steam generator. In some implementations, one or more of vent door5813, vent closure5803, and vent closure5809are configured to open in response to a nonoperating condition of one or more system elements (e.g., nonoperation of the fluid movement system, power failure, water failure, etc.). In some implementations, one or more vent closures or doors are held in a closed position using electric power during normal operation and open automatically when electric power is lost or in response to a signal indicating to open. As one example, the thermal storage unit may include a worm gear (not shown) configured to close a vent closure under electric power and an electric clutch configured to hold the vent closure in position. In some implementations, when the electric clutch is unpowered, the force of gravity pulls the vent closure open. In some implementations, the unit includes a counterweight configured to facilitate opening of one or more vent closures. In some implementations, the unit includes one or more resilient members, for example springs, configured to push or pull a vent closure open. In some implementations, one or more electrical switches are configured to control opening or closing of one or more vent closures. Further, one or more vent closures may be opened manually or based on manual control input, e.g., for maintenance mode. In some implementations, one or more vent closures are opened while a fluid blower is operating, e.g., to rapidly cool the unit for maintenance. FIG.60provides an isometric view of the thermal storage unit with multiple vents closures closed and cutaways in the outer enclosure, according to some implementations. As shown, the enclosures form multiple portions5825of a fluid passage between the inner enclosure5827and the outer enclosure5801. Fluid may move along these portions when driven by the fluid movement system (e.g., a blower5821) for dynamic insulation or passively during failsafe operation. FIG.61provides a more detailed perspective view of the primary vent closure, according to some implementations. As shown passage5829leads into the steam generator and this input is closed off from the thermal storage blocks when the vent door5813is open, but opens allow passage of external fluid into the outer enclosure (including into passage5825).FIG.61also shows an assemblage5831of thermal storage bricks. FIG.62provides a still more detailed perspective view of a hinge for the primary vent closure, according to some implementations. In the illustrated example, the vent door5813includes a hinge formed by a cylinder5833and a slot in portion5835and is configured to rotate about the hinge. In some implementations, the hinge is not centered which may cause gravity to pull the door5813open when it is not held shut. As shown, the door5813may include various surfaces configured to provide a strong seal against one or more surfaces when open or closed. As discussed above, dynamic insulation may be implemented in the TSU. The example system may also include passive failsafe safety features. When the system is switched off, thermal conduction might slowly heat up the foundation without passive venting features. One or more vents may create a chimney effect by allowing external fluid into the system, and allowing the hot fluid within the system to be vented upward out of the unit. This may allow the system fluid out at a slow rate without requiring a blower, due to the natural convective movement of fluid caused by the buoyancy of hot fluid rising through the columns. This buoyancy effect may pull cool fluid in and through the system as a passive safety measure, which opens the passage if power has been interrupted, and ensures that the system does not slowly overheat. This aspect of the example implementations may advantageously make the system intrinsically safe and allow the system to be placed in locations that may not be otherwise permitted if the exterior surfaces were unsafe (e.g., too hot) to the touch. This passive cooling may prevent the bricks from reaching temperatures high enough to melt steel reinforcing structures that provide seismic reinforcement and structural support for the bricks. This reinforcing structure may be located within the unit but outside the dynamic insulation passageway. The buoyancy of fluid may enable an automated flow of the fluid through at least one of the fluid pathways through thermal storage blocks from the bottom end of the cells to the upper end of the such that the fluid passing through the bricks and/or heating elements of the cells absorbs thermal energy from the brick and/or heating elements, even when the fluid blowing units fail to operate in case of power or mechanical failure, thereby maintaining the temperature of the unit outer walls and supports at or below their predefined temperatures. Such buoyancy-driven flow may be obtained by one or more movable panels or other ports which passively open at an upper location and a lower location within the system upon such component failure or power failure. The design of such ports and fluid flow conduits may improve the intrinsic passive safety of the unit, ensuring that critical elements such as structural supports and safety-related elements such as external surfaces do not exceed their design limits, without active equipment or the requirement for supplied power. This configuration may allow the system to achieve a controlled, stable shutdown even in the event of unexpected mechanical failure, sensor failure, or power loss to the blowers or any other control system failure. This configuration may also facilitate controlled cooling for maintenance, passively or in conjunction with one or more active blowers. Brick Materials In some implementations, thermal storage blocks are made of a refractory material (e.g., castable) having high thermal conductivity and absorption capability. The brick may be made of a predefined composition of any or a combination of alumina, aggregates like magnetite or olivine, and binders. The material selection, sizing, and fraction of aggregate in binder may be chosen to optimize strength, thermal conductivity, temperature range, specific heat, and/or cost. For example, materials of higher thermal conductivity reduce temperature differences for given heat flux, and enable the use of fewer, larger bricks. Binder materials may be chosen which set during casting, or may be chosen as materials which are thermally fired prior to use or which change composition once heated in use. The bricks may be manufactured using a mold. More specifically, the material may be provided in a powder form that is mixed with water, to achieve a consistency based on the amount of added water relative to the volume of power. The mixture is poured into a mold, and sets in the mold for a period of time. The mold is removed, and the set bricks are formed. Alternatively, the bricks may be manufactured using a brick press system or a brick extrusion system. Regardless of the method of fabrication, the bricks may be formed in a manner that reduces or eliminates unintended voids within solid block areas. FIG.63illustrates a composition3200of the brick3201according to the example implementations. An aggregate3203,3209is provided in a binder3205. Additionally, heat conductivity elements3213, phase change materials3211, and/or strengthening elements3207may also be included. Brick elements may also include elements which improve the mechanical strength of the material, particularly in tension, such as needles or fibers or wires, and may include materials designed to change in physical ways that absorb and release heat, such as reversible thermochemical reactions or phase changes such as melting and freezing. These materials may be used selectively in some of the bricks, with different bricks having different compositions. The predefined composition of the thermally conductive materials and the predefined dimension of the bricks being used, and the thermo-electrical attributes of the heating elements corresponding to each of the bricks, may be chosen such that each of the bricks corresponding to a cell may be heated uniformly so that a substantially constant temperature profile is maintained along the length (or height) of each of the cells for a predetermined time. The foregoing example implementation may have benefits and advantages, including slowing temperature ramp, as well as reducing the generation of hot and cold hot spots, mechanical stress, thermal stress, and cracking in the bricks. Further, the use of multiple bricks to form a single cell may facilitate larger channel surface area and lower heat flux per unit area. Bricks—Pretreatment Thermal storage blocks and other components may also benefit from pre-treatment and conditioning. For example, a brick may be exposed to one or more thermal cycle with controlled heating and cooling rates, either prior to installation or within the storage system prior to being put into service given that the initial cycles may have a larger impact on its mechanical properties than subsequent cycles. Storage Unit Components/Integration For the storage unit, shipping containers may be used, but are not limited thereto. For example, the storage unit may be on the order of 6 meters tall, housing the stacks of bricks. The containers include electronics and wires coupling the containers to the brick housing structure that is protected to avoid damage due to external elements such as rain. The electronics may remain at ambient temperature, allowing for the use of standard, off-the shelf components, and reliability. A steam generator is coupled to the storage system, and cool fluid flows over, under and around the stacks. The heater elements may be integrated inside and with the brick to heat the storage media electrically during the charging period, such as during the day (or at a time that may be determined by other factors such as availability of electricity at a relatively lower cost). The structure houses a stack of bricks with fluid passages that run substantially vertically through them; the hot fluid exits through a duct at the top of the stack and adjacent to pipes, so as to convert water to steam. Cooler fluid may be recycled or may exit the back side of the structure, for example. The unit may have, at an end, a wall with holes and the end of wires protruding and the jumpers to connect the wires from one side to the other. At the other end of the unit, the containers may be configured with a distribution of bus bars provided for electrical distribution to provide the power to the strings of wire heating elements. The bus bars are connected back to the controllers inside the containers. The heating elements may be serviceable and replaceable, if needed, by sliding into and out of the openings passing through the building. Old elements, or elements that otherwise require servicing or replacement, may be pushed or pulled out and replaced with a new one without the need to move other elements such as the bus bars. Thus, the unit may be deenergized, the connections to the bus bar may be detached (e.g., unscrewed) from the container side, and the heating elements may be removed from the opposite side. New elements may be inserted from the opposite side and screwed into the bus bars from the container side, and the unit re-energized. During such a maintenance period, insulation may remain in place with the wire protruding through an insulating plug at the end. The space between the inner and outer roof may contain the relatively cooler return fluid, and the inner enclosure may contain the very hot fluid coming off (e.g., exiting) the top of the stacks. An internal duct is provided that facilitates transport of the fluid through a duct through the steam generator, where the fluid exits. A fan located at the output of the steam generator may be placed in cold fluid, in the cavity between the inner and outer rooms. This configuration allows the fan to avoid needing to have the metallurgy required for higher temperature operations, and increases its reliability. The hot fluid duct feeding into the steam generator may become expensive due to the high temperature of the fluid. It may also have a large pressure drop, since the fluid has expanded to multiple times the volume it was when it was cool. Thus, the hot fluid duct must be significantly larger than needed to handle the cool fluid. However, taking the fluid off at one side of the inner roof may reduce the cost of the high temperature duct for several reasons. For example, the quality of insulation that would otherwise be needed is not required, because any heat which is leaking out of that high temperature duct will warm the inlet fluid. Further, the hot fluid duct is very short and direct. A duct that needs to withstand such high temperatures is expensive, therefore limiting the length is beneficial. Further, the space between the inner roof and the outer roof may also include a divider, and a fan may be provided to control return fluid. On either side of this dividing wall, the return fluid is drawn back into the heating stack. Around the edges of the inner roof, a vertical duct is formed to allow the cooler fluid to descend to the bottom of the unit and return to the bottom of the brick stacks. According to an example implementation, there is no other place (other than the duct connecting to the steam generator) where the outside of the unit experiences the full temperature of the system or the full temperature of the unit. This configuration may dramatically simplify the insulation in other locations and may dramatically reduce the losses and costs, at least because while there will be energy exiting this stack of bricks and through this wall, the incoming fluid is slightly preheated before it gets back to the stack of bricks. The example implementation may be modified by optionally making it self-supporting and using a system of spacers to keep and maintain the spacing between the bricks. Conventionally, brick aspect ratio is chosen so that individual bricks do not topple in an earthquake, for example, by having a base width about 40%, e.g., 40%, of the height or greater. Spacers may be used to impart this stability on bricks that do not have the desired aspect ratio, but interlocking smaller bricks together to make a larger brick that has the desired stability. In this example, the spacers transfer forces from bricks above it and to the ones below and to the side through compression. This essentially makes the structure into a pyramid, an inherently self-supporting and stable structure, without the need for excessive wall bracing. The spacers may be made of a high temperature refractory or ceramic material and may also include features to interface with wire hangers. Thermocline and Radiation Chamber The first temperature of the bricks and the heating elements may be kept higher than the second temperature of the fluid for controlled discharge of thermal energy from the first section into the second section. For instance, the heating elements may be heated at a first predefined temperature of 1200° C. so that the bricks or cells also gets heated up to 1200° C., and fluid at 250° C. may be supplied through from the bottom end of the cells and heating elements, so that the fluid, upon absorbing thermal energy from the bricks and/or heating elements may attain the second temperature of 800° C. Further, the heated fluid of 800° C. may pass through the conduit such that the fluid inside the conduit may be converted into steam. Various structural aspects of the thermocline are provided below. The bricks may be arranged to create a fluid passage between the bricks, in a repeating pattern. This results in the brick providing additional surface area for the heat in the brick to transfer to the fluid. The brick becomes a heat sink system. The fluid flow path is substantially vertically. Fluid comes into the bottom, goes up through these channels, gets heated as it goes up and escapes the top hot and goes into the roof area. The bricks may optionally have a consistent amount of thermal mass along their length, to help maintain temperature uniformity and avoid significant narrowing that may cause hot spots. Optionally, the bricks may include a chamfer at the top and bottom, so that if the bricks are slightly misaligned, the fluid pathways are not closed. The fluid pathways may be relatively narrow and it may be important that the bricks are not offset from each other, which would close the fluid pathways and reduce the fluid flow. Accordingly, chamfers and other features at the top in the bottom of the bricks may have the advantage of preventing misalignment. The bricks of the example may be stacked, such as in a stack six or more bricks high. Some of the bricks have a corresponding heating element that winds through and is hung from a feature in the structure. The bricks are spaced and designed such that they are self-supporting system. From one slot for one set of heater wires to the next, a relatively small space, such as about 30 centimeters (for example, 30 centimeters), is required for the required performance because for the heating time available during the day, the dimension is limited by the conduction rate. Larger dimensions may result in sections of the brick not being efficiently used for thermal storage. Optionally, the size of the fluid flow pathways may be adjusted to tune the fluid flow velocity in different areas, to counteract the temperature profile that already exists in the brick when it is heated. In other words, when the brick is heated, the side of the brick closest to the heater gets hottest and gets progressively cooler moving across the brick. If the energy is extracted equally from the whole system, the output fluid temperature would be a gradient reflecting the brick temperature gradient; hottest fluid near the wires and cooler fluid further from the heaters. Having larger pathways closer to the heater element may create less resistance to fluid flow, resulting in higher fluid velocity, and smaller channels further away from the heater element, which reduces fluid velocity in those regions, to obtain a more homogeneous fluid temperature. As the fluid traveling at higher velocity is in the pathway for less time and is in contact with the brick for less time, that fluid exits the pathway cooler than fluid traveling slower through the same section. The side of the brick with the bigger channels is hotter in the present example implementations; thus, size of these pathways may be tuned such that the fluid that comes out of the wide slots in the hottest part of the brick is nearly the same temperature as the fluid that comes out of the narrower slots in the lower temperature part of the brick. Thus, by tuning the geometry of the brick and fluid pathways, the performance of the thermocline system may be improved and optimized to match the expected and desired charging and discharging characteristics. In addition to using differential fluid flow to even output temperature, by generally increasing or decreasing the overall fluid flow through the system, the temperature of the output fluid may be controlled. According to some example implementations, the bricks are blocks that are separate and effectively have voids. These voids, which might be large voids, between the bricks in the stack create radiation chambers. In these example implementations, the energy may be transferred from the wire to the brick primarily by radiation energy transfer. When the wires get hot, the radiation contacts the brick and comes into radiative balance with a brick, where the brick is cooler than the wire trying to come up to temperature, and radiation from the brick cools the wire. Energy from the wire is thus exposed to more surface area of brick as compared with convective heating. The energy from this wire when it radiates down into this cavity energy penetrates into the cavity and becomes exposed to more surface and mass of brick, instead of just the surface right next to it, which gets a very high flux density and very high energy density. According to this example implementation, some bricks may radiatively heat each other after being heated by the wire. Thus, the system may achieve both direct and indirect radiant heating of brick surface as part of the heat transfer. This design allows the heater element wire to be further spread out. Without radiative cavities designed to heat large surface of brick in this way, e.g., if conduction as the primary mechanism by which heat is being transferred, the design may be limited to a relatively small distance such as between 0.3 and 0.5 meters of space between wire curtains in some implementations, when matched to heating profiles for solar heating, as there is not enough time to heat the center of the mass of the bricks. By using radiation cavities, the wire curtain spacing may be spread out to more than 0.5m and still efficiently utilize the entire mass of the brick. This allows for a reduction in the wire count. One benefit of this example implementation is that the total wire count may be reduced, for example, from 3,400 wires to potentially approximately 96 wires (for example, 96 wires) while transferring the same amount of energy as was being transferred from the 3,400 wires. Further, this example implementation, may use wire having a diameter in the range of 2.5 mm to 8 mm. Design of Stack—Materials During the course of normal operation of the thermal storage system, care may be taken to ensure that certain temperature ranges which may cause early failure are moved through quickly. For example, FeCrAl type alloys are known to embrittle if a significant amount of time is spent between 400-500° C. Different heating elements or bricks may have other sensitive temperature ranges where mechanical, thermal or physical properties are negatively affected. The control system may take this into consideration to avoid damaging the materials prematurely. The thermal storage system may be designed in a way that some sections are made to handle higher temperatures. For example, a top section may comprise higher temperature rated heating elements, such as ones consisting of primarily SiC or MoSi2, and higher temperature rated brick, such as tabular alumina. Such a section could be heated, as required, to temperatures reaching 1500 C, 1600 C or higher. The geometry of bricks and wires may be different than those in another section of the thermal storage unit, to optimize performance, cost or mechanical stability. A second section of the storage, for example, in the lower part of the stack, could have lower temperature rated heating elements, such as metal heating elements in the FeCrAl class, and bricks that are a different material type, selected for cost, performance and mechanical properties as more load is placed on the bricks at the bottom. Flow Mixing Structures Additionally, the flow channel through the brick stack may be modified to facilitate or promote the mixing of gas. These modifications may reduce or eliminate hot spots and cool spots in the main stream. For example, the bricks may be structured (e.g., by fins or an arrangement of the slots) or assembled in a manner that directs the fluid to promote swirling or mixing of the fluid in the chambers, to improve heat transfer of the convection. Such mixing may even out temperature gradients, and have more even thermocline, and better performance, in addition to the benefits of radiative and reradiative heating, as explained above. This effect may be particularly advantageous at lower temperatures, or the beginning of the charge or late in the charge. Further, the greatest thermal gradient stress, which typically occurs most acutely at the beginning and end of the charge, is reduced. Additionally, cool bypass gas in the upper region of the stack may be blended by inducing swirl or turbulent flow, by a stationary auger or other feature at the top of the stack, with the gas discharged from the stacks, to obtain a more homogeneous temperature. For example,FIG.64shows a side view6401and an isometric view6403of a stationary auger6405at the top of the stacks, which may be used in combination with diverters6407, to channelize and blend the output fluid flow. As shown in greater detail inFIG.65, the diverters such as651at the top of the stacks divert the gas sideways instead of vertically, to create a swirl. Heating Element Traditional approaches may have problems and disadvantages associated with the heater for the thermal energy storage cells. For example, a traditional heater or heating element may experience problems and disadvantages such as mechanically induced chemical failure, which is also known as spalling. More specifically, scale growth may occur on the heater to a point where thermal stresses cause failure at an interface between the scale and the substrate. A result of the scale growth is flaking and loss of aluminum, until the aluminum reservoir reaches a critical point. Additionally, intrinsic chemical failure may occur when aluminum oxide breaks down, such that the aluminum migrates outward and the oxygen migrates inward, until the aluminum reservoir reaches a critical point. As a result of the foregoing related art problems and disadvantages, a phenomenon known as “breakaway oxidation” may occur, where non-protective Cr2O3 (chromium oxide) and FexOy (iron oxide) scale quickly, and eventually lead to bulk oxidation and failure of the heating element. Thus, the reliability and lifetime of the heating element is substantially shortened. As explained above, resistive heating elements are provided in channels that are formed between stacks of bricks at repeated horizontal and vertical positions in the units. The resistive heating elements receive electrical energy from the source, which may be a renewable or another source of variable electricity. The resistive heating elements release the electrical energy as heat, which is radiated to the stacks of bricks as explained above. The resistive heating elements may be in the form of wire, which may be in the form of coils or wires, ribbons, or rods which pass through the stack in channels oriented in a direction parallel to heat transfer fluid flow or extend through the stack in channels transverse to heat transfer fluid flow. According to an example implementation, coiled heating elements may be positioned in grooves running across the top and bottom of one or more bricks that may be stacked together. The heating elements may pass from one side of the unit to the other. With a jumper on one side and the coming back through the other side, an electrical circuit may be completed. The coils may be wired into series and parallel, to match the voltages that are being worked with. This diameter of wire may reduce the resistance of the long wire string. As wire may be purchased on a mass basis, and thinner wire has additional processing costs, which may result in a cost savings of hundreds of thousands of dollars for one system, which is an added benefit. By using a thicker diameter wire, the overall life of the wire may be significantly increased because there is no longer cross-sectional wear from the heating or cooling of the wire, and the corrosion of the wire is much less rapid due to the larger cross section, even if the same corrosion rate. Further, increases of the wire diameter may further be feasible, potentially as high as 8 mm. One example implementation has features that restrict the heating elements from contacting the brick or each other, in case they undergo deformation. Such a feature could be a hook on multiple positions, for example, at the top and bottom extremes. FIG.66(A)-(C) illustrate various configurations of the resistive heating elements according to the example implementation. Resistance heaters may be individually wired, wired in groups that connect resistance heaters in series, in parallel, or in a combination of series and parallel. As shown at4700a, heaters4701,4702extend through the refractory material. Heaters are installed into conduits4711after assembly of the refractory material, or during assembly of the material. Protective tubing4707may be used during installation and may be removed mechanically or melted or combusted by application of heat by the heater. Electric power connections4704are joined to heaters at points4703with connections4705athat prevent excessive heat build-up at connection points. Two or more heaters may be connected by successive connections4705,4706before connection to power distribution4704. As shown in the drawing at4700, two coil-type heaters4701are connected by a connection4706, followed by another two heaters in series along power connector4704. Wire, rod, and ribbon-type heaters4702may be similarly connected. As shown in4700b, a refractory storage medium4710, which may be the stacks of bricks, is provided with gaps or passages4711for the inclusion of the resistive heating elements. Further, the heaters may be of a ribbon type4702, or a coil type4701. Optionally, the heaters may be enclosed in a conduit4707as explained above. As shown at4700c, heaters4701with power connections4704are arranged with parallel links4709such that multiple heaters or series-sets of heaters are connected in parallel to a single power distribution connection. Operation of the power connections may be at voltages in the hundreds of volts to tens of thousands of volts. Voltages at or below 5 KV may be selected based on considerations such as safety, costs, and reliability. In some exemplary implementations, the heater(s) or heating elements may be a resistance wire extending along the length of the channels of each brick, where each of the heating elements may have predefined electro-thermal attributes such as resistance, electrical conductivity, thermal conductivity, cross-section area, and the likes, such that each of the heating elements may be heated up to the predefined temperatures upon receiving electrical power from the electrical power sources. Electrically, a loop may be formed by a heating wire that starts at an end of a first channel, passes through a jumper at the other end of the channel, and returns via another channel. Adjacent stacks of bricks may be phased apart (e.g., 3-phase, for adjacent stacks of bricks, such that the stacks forms a group, or cell). The group of stacks, or cell, may be resistance-matched so that the performance of the stacks is consistent with respect to one another. The entire two of groups may form a zone that is on a controller. Vertically, different zones (e.g., rows of stacks) may be on different controllers, and may thus be resistance-matched at a different resistance from different vertical levels. Further, the resistive heaters may be controlled such that the stacks are heated in an uneven manner. More specifically, the upper portions of the stacks may be preferentially heated. The controllers may control the vertical layers of the stacks separately, such that the heaters on different layers of the stack may be turned on or turned off at different times. For example, the controllers for the upper layers of the stacks may turn on the heating elements of the upper layers of the stack in advance of the controllers for the middle or lower layers of the stack turning on those heating elements. Further, this approach takes into account the different in brick height and mass between the bricks at the lower layers, which have a lower height and mass, as compared with the bricks at the upper layers, which have a greater height and mass. Thus, the upper brick layers will have a hotter temperature than the lower brick layers, and the thermocline is maintained. The controller may set the temperature and the timing of the heating for the layers of the stack based on sensor feedback, or based on system models, to determine the temperature of the layers, or a combination thereof. The above example implementation of the brick design may be modified by stretching the above design and the heater element vertically. Thus, instead of being a round spiral, the heater may be a flat coil which goes into the brick and this allows every wire to have more surface area and more exposure with the brick. This also allows the number of wires in the system to be reduced, which may have a benefit of lowering the cost of the heater elements. A wire irradiating to a larger surface may allow for more watts per centimeter of energy to be pushed in. The larger the surface area, the more brick is heated, which may have substantial implications on the temperature of the wire, because the surface temperature of the brick that the wire is exposed to sets a limit. A top wire temperature has direct implications on its lifetime, and the brick wall temperature that the wire is exposed to determines how much energy flux can be safely pushed through the wire. Thus, the example implementation involves a brick volume, exposed surface area, and wire temperature. According to an example implementation, service is provided for the heater wire by forming a tall system wound up and down vertically and heating the sides of two separate bricks. The bricks are formed with fluid flow channels, and are substantially taller than the bricks disclosed in the foregoing example implementations. Larger bricks with the substantially same efficiency may allow fewer parts to be manufactured, and for wires to be spaced out further. This example implementation may have the added benefit of reducing cost of materials and assembly. The bricks may be extruded, pressed or cast and are formed with channels for the fluid to flow through. These channels, or slots, may provide a superior surface to volume ratio over holes or other shapes. The slots may or may not extend all the way at the edge closest to the heating element to concentrate the thermal mass close to the elements so that the energy transfers quickly. As shown inFIG.67, the heating wire6701may be hanging from a rack6703that is held in place by the hangers6705and a rod6707. Spacers6709are provided between the coils6711at the rod6701, to prevent surfaces of the wire6701from touching. Optionally, spacers may be added at the middle or bottom (not shown). Further, the cross-section, geometry, or materials may be adjusted. For example, a twisted ribbon6721as shown inFIG.68, or a flat ribbon6731as shown inFIG.69, may be provided. Similarly, the different heaters may be used at different vertical levels of the stack. For example, the heaters near the inlet flow at a lower portion of the stack may require a different design than the heaters near the discharge at the top of the stack, due to the different fluid flow conditions. Coating Heating Elements Other methods which may be employed to increase service life includes material pre-treatment and conditioning. For example, FeCrAl type heating elements are known to grow a protective, α-alumina scale on the surface which greatly reduces the rate of oxidation of the bulk material. However, at temperatures below 800-1000° C., a less protective form of alumina initially forms. To impart the protective effect of the dense α-alumina, the heater elements may be heated to a controlled temperature and duration above 1000° C. prior to being placed into service. This may be performed pre-installation or inside the thermal storage system post installation. The wires may also be pre-treated to change the surface chemistry for longer life. For example, it is known that the aluminum reserve in the bulk FeCrAl material is an important limiting factor for oxidative failure. Because FeCrAl materials with aluminum fraction significantly higher than about 5%, e.g., 5%, are not suitable for hot processing, a process which adds additional aluminum may be beneficial. Such processes may include hot aluminizing, aluminum electro-plating, sol-gel processing and aluminum plating followed by anodizing. The surface treatment may also be made to increase the emissivity of the surface such that the average temperature of the heating element may be lower than without the treatment. Replaceable Heating Elements Individual heating elements may be configured to be removed and replaced without disassembly of the cell. For example, a broken or failed heating element may be pushed or pulled through the cell using a mechanical puller or pipe to remove and a replacement element placed in the cell using a pipe or other specific tool. As may be understood by a person of ordinary skill in the art, the resistivity of heating elements may change over time due to gradual physical effects from normal operation including wear, oxidation, and changing in metal crystal structure and alloying. In some example implementations, the replacement element may be sized or constructed to produce a resistivity that mirrors a projected resistivity of surrounding elements that may have degraded over during operation of the system. For example, it may be anticipated that a portion of heating elements will fail within a prescribed time, such as 3 years, of operation, and replacement elements installed after three years may be designed with a resistivity that mirrors projected resistivity of the remaining original elements that are still operation but have changed resistivity over the period of operation. Similarly, different resistivities may be chosen for heating elements installed during later periods. Control System In various implementations the system includes a control unit or control system operatively coupled to disclosed elements such as the electrical energy sources, the heating elements, the air blowing units, the pumps, etc. In one implementation, the control unit is configured to enable the electrical coupling of the heating elements with the electrical energy sources. The control unit may switch the electrical connection of the heating elements between different electrical energy sources based on availability and cost per kWh of the electrical energy sources. During low load hours, the cost per kWh of non-renewable energy sources is generally relatively lower and sometimes negative. However, it may not be feasible for the non-renewable energy sources to switch off electrical power generation during these low load hours. Thus, during these low load hours, the control unit may electrically couple the system with an electrical energy source that is providing a lower cost per kWh of energy. The control unit may further control the air blowing units to enable controlled flow of fluid between any combination of one or more insulated cells that include thermal storage block assemblies and the outside environment, and also control one or more pumps to facilitate the controlled flow of fluid and steam through the conduit. In an example implementation, system pumps and blowers are operable at variable flow rates, such that energy production and steam generation may be adjusted from a nominal full rate in steps or continuously down to a lower rate. Such minimum rate may be 10%, 20%, 30% of peak output, or another rate. The system controller may be configured to issue commands to adjust the flow rate of the input liquid pump and the blower so as to allow energy delivery at multiple rates automatically, based on manual commands, or both. In another example implementation, the control unit may be in communication with a system associated with an electrical load or other industrial loads. The control unit may be configured to monitor the demand for hot fluid, steam or electrical power at the load, as well the available energy being stored in the system, and may accordingly charge the system by electrically connecting the heating elements to the electrical energy sources. For instance, when the control unit finds that the demand of the load is higher than the available energy currently stored in the system, then the control unit may electrically couple the heating elements of the system to the renewable or non-renewable energy sources to meet the demand of the load. If the available electrical energy being received by the electrical energy sources is reduced, then during charging mode, the control unit may electrically connect heating elements associated with a predetermined number of cells among all the cells of the housing, such that only the heating elements of a proper subset of cells may receive the limited electrical energy and become heated, and the other heating elements or cells remain electrically disconnected from the electrical energy sources. Later, during discharging, the control unit may allow fluid to be passed through the heated cells to transfer the stored thermal energy to the conduit so the temperature of the fluid at the conduit remains at the delivery temperature, thereby reducing or preventing any damages or failure in the steam production system, and potentially maintaining continuous and controlled steam production. The control system may generate a signal such as a command to activate one or more switching elements which in turn control source electrical energy input to resistive heating elements. The control system may directly or indirectly command the operation of active switches which selectively interrupt current flow so as to deliver a chosen average power. Such switching patterns may be carried out by thyristor-type switches which are continuously on or selectively commanded to switch so as to deliver a lower power by selectively conducting during chosen patterns of half-cycles. A plurality of such switches may be chosen to operate in a pattern such that during each half-cycle of an AC current flow, the average load is constant. One such pattern would have the same or similar number of switches turned on during each half-cycle, even though any given switch might be turned on only once during a sequence of multiple cycles. Other switching patterns may be carried out by insulated-gate bipolar transistor (IGBT)-type switches which operate at frequencies higher than 120 Hz and which selectively conduct or block current in a pattern to provide continuous conduction or partial power whether incoming power is in the form of AC or DC. The control system may determine switching decisions based in part on various parameters, such as the design of the heating element, including its resistance per unit length, its material surface area, its material of construction including its performance with temperature (temperature-related effects may include metal recrystallization and/or dealloying, oxidation, spalling, creep, thermal expansion, and wear) the temperature and size of the surface area surrounding the heating element, local temperatures along the entire heating element length (including support points or points of contact with solid media and points of electrical connection with other conductors), etc., or some combination thereof. Overtemperature at points of connection may be reduced or prevented by arranging regions of lower electrical resistance proximate to such connections, e.g., by winding multiple strands of wire together, changing conductor cross-section, making such connections outside high-temperature regions of the storage unit, or providing local heat-sink/cooling elements at such points. FIG.70illustrates the resistive heating element7000according to an example implementation. The resistive heating element7001is positioned in a conduit7003having an outer wall having a surface temperature as indicated by7007. The surface temperature7007depends on the bulk temperature distribution of the brick, its thermal conductivity, and the radiative heat flux. Switching decisions may be based in part on the design of the heating element7009, including its resistance per unit length, its material surface area, its material of construction including its performance with temperature (temperature-related effects including metal recrystallization and/or dealloying, oxidation, spalling, creep, thermal expansion, and wear) the temperature and size of the surface area surrounding the heating element7007,7009, and local temperatures along the entire heating element length, including support points or points of contact with solid media7011,7013,7015. The surface temperature of the heating element7001,7017may depend on the wattage per unit surface area of heating element, the ambient air temperature around the element, whether or not air is flowing in the conduit in the region defined by7003and7005, and the surface temperature of the enclosing material7007. The surface temperature at7007depends on the bulk temperature distribution of the brick, its thermal conductivity, and the radiative heat flux; radiative heat transfer dominates. Since this is proportional to the difference of the temperatures in degrees Kelvin to the fourth power, as the refractory material approaches the maximum operating temperature of the heater, the power flowing through the heater should approach zero. In one implementation, the surface temperature of the heating element depends on the wattage per unit surface area of heating element, the ambient air temperature around the element, whether or not air is flowing in the conduit, and the surface temperature of the enclosing material. The surface temperature depends on the bulk temperature distribution of the brick, its thermal conductivity, and the radiative heat flux. Radiative heat transfer may dominate in disclosed implementations. Because radiation transfer is proportional to the difference of the temperatures in degrees Kelvin to the fourth power, as the refractory material approaches the maximum operating temperature of the heater, the power flowing through the heater should approach zero. In some implementations the control system algorithms include models of the thermal storage unit. These models approximately simulate the temperature at various points within the storage unit, as well as instantaneous and forecast temperatures based on heater power input. Accordingly, heater life is advantageously preserved, by incorporating weather and seasonal inputs into the controller, including the use of forecasting. The models may adapt to changes in the configuration of the storage unit, including the presence of missing or failed heaters or heater controllers, the presence of blocked heat transfer channels, the presence of scale formation in the steam generation section, or other operating/maintenance matters. In one implementation, the control system confirms and compares simulation models to select measurements of temperatures, flows, and power levels at various points within the system. The control system may consider the models in control calculations governing power to the heating elements. For example, wall temperatures may be a limiting factor in the current input power allowable for a given heater, with limits calculated based on peak refractory temperature and peak wire temperature. A constant-wattage (constant-Q heat flux) charging may not be feasible without the heater temperature significantly exceeding the refractory temperature. The control system responding to such constraints may command charging wattage (e.g., Q heat flux) patterns in time during charging, where initial low-rate heating establishes heat conduction patterns, charging is raised to high rates for part of the charging time, and charging rate drops as material temperature rises, such that the final top temperature is approached asymptotically at slow rates, without exceeding top heater temperatures. Heat transfer fluid may be flowing in the adjacent fluid conduits during charging, allowing charge plus discharge operation concurrently. In some example implementations, heat transfer fluid may be flowing in the conduit that carries the heater element. The resistance per unit length of the heating element may vary, and/or the heat production per unit length may vary, so that (for example) a conduit which has heat transfer fluid flowing axially along the heater may require less heat near the fluid outlet than near the fluid inlet. Advantages In addition to those advantages described above in Section I, the example implementations relating to thermal blocks and assemblages may also afford various advantages relative to traditional approaches. For example, traditional approaches commonly suffer from uneven heat distribution, wear and tear due to the heating and cooling cycles of the bricks, and safety and maintenance issues. The implementations within this disclosure, however, attempt to mitigate various such problems by applying radiative heating (including horizontal radial radiation within the radiation chambers) in combination with fluid flow pathways, to produce a distribution of heat that is more uniform than that achieved by traditional heating techniques. As a result, problems and disadvantages associated the art may be overcome, such as inefficient power storage, degradation, damage and breakdown of various elements (e.g., the heating element, the bricks, the enclosures, etc.), unsafe hotspots, etc. Disclosed dynamic insulation techniques may advantageously improve insulation efficiency, reduce insulation costs, or both relative to traditional techniques. Further, disclosed passive cooling techniques may improve the safety of the thermal storage system. Various disclosed techniques may reduce maintenance complexity relative to traditional techniques. The storage media blocks may be arranged in an assemblage that allows relative movement to accommodate expansion and contraction by individual elements. Also, the array is arranged such that cycles of thermal expansion align the elements of the array to preserve the integrity of the array structure, the integrity of the heating element conduits, and the integrity of the heat transfer gas conduits. Further, because the heat is more evenly stored, waste of heat is also reduced or avoided. Additionally, the example implementations may have another benefit, in that it may be easier to maintain and replace the heater modules, heating elements, and bricks. Further, the example implementations have increased efficiency. For example, the brick and stack configurations disclosed herein may produce an increase in the AT of the bulk material over the course of charging and discharging to allow the bricks to store more megawatt hours per kilogram of material, as compared with current designs. III. DC/DC Conversion In many power transfer systems, alternating current (AC) is employed to transfer power from a generating source to a load. In such systems, passive equipment and transformers need to be energized for the system to work, resulting in the circulation of reactive energy. Additionally, the transfer of AC over distances can result in losses due to impedance of transmission lines coupled between the generating source and the load. In some cases, the power generated may be intermittent. For example, when the generating source is photovoltaic cells, the power being transferred is based on the illumination of the photovoltaic cells, which can vary over the course of the day. As the power drops, the efficiency of the AC transfer system can be further degraded. To improve the efficiency of such power transfers, direct current (DC) transfer can be employed which use multiple input DC voltages to generate a higher voltage for transmission. In some cases, the transmit voltage can be decomposed into multiple smaller voltages at the load end of the transfer system. As described below, the losses associated with converting DC sources to AC for transfer can be eliminated due to lower inductive and eddy current losses. Additionally, ohmic resistive loads can be lower further improving efficiency. A block diagram of such a thermal storage system the employs DC power transfer is depicted inFIG.71. As illustrated power transfer system3100includes generator circuits3101A-C, converter circuit3101, converter circuit3102, and thermal storage unit3104. Generator circuits3103A-C are configured to generate DC voltages3107A-C, respectively. In various implementations, generator circuits3103A-C may employ renewable energy sources such as solar or wind. DC voltages3107A-C may, in some implementations, be time-varying voltages. For example, in some cases, the respectively levels of DC voltages3107A-C may be based on variation in illumination of photovoltaic panels. Although only three generator circuits are depicted in the implementation ofFIG.71, in other implementations, any suitable number of generator circuits may be employed. As described below, converter circuit3101includes multiple sub-converter circuits, each including a first input circuit and a first output circuit. The first input circuit is configured to receive one of DC voltages3107A-C. The first output circuit is galvanically isolated from the first input circuit and is configured to generate a corresponding one of DC voltages3109A. Converter circuit3101is configured to combine DC voltages3109A to generate transmit voltage3108. As described below, converter circuit3102also includes multiple sub-converter circuits, each including a second input circuit and a second output circuit. The second input circuit is configured to receive, via transmission line3106, a portion of transmit voltage3108. The second output circuit is galvanically isolated from the second input circuit and configured to generate a corresponding one of DC voltages3110derived from the portion of transmit voltage3108received by the second input circuit. Converter circuit3102is configured to combine DC voltages3110on output bus3105. It is noted that, in some implementations, DC voltages3110may be coupled, in parallel, onto output bus3105. Thermal storage unit3104includes heating element3111coupled to output bus3105. In various implementations, heating element3111is positioned to heat thermal storage medium3112using power received via output bus3105. As described elsewhere in the specification, thermal storage unit3104may be implemented using a variety of different thermal storage mediums. In some cases, voltages from multiple energy sources can be combined into a transmit voltage that may be used directly by a load. A block diagram of an implementation of power transmission system for a renewable energy source system is depicted inFIG.72. As illustrated, power transmission system3200includes converter circuit3101, renewable energy sources3202A-C, and thermal storage unit3104. Converter circuit3101includes sub-converter circuits3203A-C. Renewable energy sources3202A-C are configured to generate DC voltages3205A-C, respectively. In various implementations, renewable energy sources3202A-C may be implemented using photovoltaic cells, wind turbines, or any other suitable renewable energy source. DC voltages3205A-C may, in some implementations, vary in time due to the intermittent nature of illumination of the photovoltaic cells, the absence of wind, and the like. Although only three renewable energy sources are depicted in the implementation ofFIG.72, in other implementations, any suitable number of renewable energy sources may be employed. Sub-converter circuits3203A-C are configured to receive DC voltages3205A-C, respectively. In various implementations, sub-converter circuits3203A-C are configured to generate output voltages3206A-C using corresponding ones of DC voltages3205A-C. As described below, sub-converter circuits3201A-C include respective input circuits and output circuits that are galvanically isolated by corresponding transformers. Sub-converter circuits3203A-C are coupled in series to combine output voltages3206A-C to generate transmit voltage3108. In various implementations, transmit voltage3108is a sum of output voltages3206A-C. By coupling sub-converter circuits3203A-C in series, a voltage larger than any of one of DC voltages3205A-C can be generated to aid in the transmission of power to thermal storage unit3104. Moreover, coupling sub-converter circuits3203A-C in series eliminate the need to detect failures in any of renewable energy sources3202A-C. If any one of renewable energy sources3202A-C stops generating its corresponding one of DC voltages3205A-C, the corresponding one of sub-converter circuits3203A-C generates a zero output voltage which still allows the generation of transmit voltage3207by adding the output voltages of the remaining ones of sub-converter circuits3203A-C. Although converter circuit3201is depicted as including only three sub-converter circuits, in other embodiments, any suitable number of sub-converter circuits may be employed. In some cases, the number of sub-converter circuits included in converter circuit3101may correspond to a number of renewable energy sources. Alternatively, multiple renewable energy sources may be wired together and a number of sub-converter circuits may be based on a desired magnitude of transmit voltage3108. Thermal storage unit3104includes heating element3108configured to heat thermal storage medium3109using transmit voltage3107. In various embodiments, thermal storage unit3104may be coupled to the output of up-converter circuit3101using a high-voltage DC cable capable of handling the current drawn by thermal storage unit3104at the value of transmit voltage3107. As described elsewhere in the specification, thermal storage unit3104may be implemented using a heating element which can be used to heat a variety of different thermal storage mediums. Turning toFIG.73, a block diagram of an embodiment of a power receiver system for a transmitted direct current voltage is depicted. As illustrated, power receiver system3300includes converter circuit3102, and load circuit3306. Converter circuit3102includes sub-converter circuits3302A-C that are coupled in series across transmit voltage3108. It is noted that while sub-converter circuits3302A-C are depicted as being across transmit voltage3108, in other embodiments, sub-converter circuits3302A-C may be coupled across any suitable DC voltage. By coupling sub-converter circuits3302A-C in series, transmit voltage3108is divided into voltage portions3303A-C, with corresponding inputs of each of sub-converter circuits3302A-C being exposed to only a portion of transmit voltage3108. In the illustrated embodiment, since there are three sub-converter circuits, each of voltage portions3303A-C is a third of the value of transmit voltage3108. Using series-coupled sub-converter circuits may, in various embodiments, allow for the use of lower voltage components in sub-converter circuits3302A-C, thereby saving cost and circuit complexity. Sub-converter circuits3302A-C are configured to receive corresponding ones of voltage portions3303A-C. For example, sub-converter circuit3302A is configured to receive voltage portion3303A, while sub-converter circuit3302B is configured to receive voltage portion3303B. Sub-converter circuits3302A-C are further configured to generate, using corresponding ones of voltage portions3303A-C, corresponding ones of load voltages3304A-C. As with sub-converter circuits3203A-C, sub-converter circuits3302A-C include input and output circuits that are galvanically isolated from each other. Use of such isolation may prevent possible damaging currents flowing directly from cables carrying transmit voltage3108to load circuit3306. Although converter circuit3102is depicted as including only three sub-converter circuits, in other embodiments, any suitable number of converter circuits may be employed. In some cases, the number of sub-converter circuits included in converter circuit3102may be based on a value of transmit voltage3108and desired values of load voltages3304A-C. For example, if smaller values are desired for load voltages3304A-C, additional sub-converter circuits may be employed to split transmit voltage3108into a larger number of smaller portions. Load circuit3306is coupled to output bus3105and is configured to perform a function or operation using a voltage level of output bus3105. It is noted that load circuit3306may be any suitable circuit or unit that employs a DC voltage to perform a function or operation. In various embodiments, load circuit3306may be part of a thermal storage unit (e.g.., thermal storage unit3104) while, in other cases, load circuit3306may be part of an electric vehicle charging system, or other battery charging system. For example, load circuit3306may include charging circuit3207configured to charge battery3208using power received via output bus3105. Turning toFIG.74a block diagram of an embodiment of a sub-converter circuit is depicted. As illustrated, sub-converter circuit3400includes DC converter circuit3401, transformer3402, output circuit3419, control circuit3405, and control circuit3406. Output circuit3419includes rectifier circuit3403and output voltage generator circuit3404. In various embodiments, sub-converter circuit3400may correspond to any of sub-converter circuits3203A-C or sub-converter circuits3302A-C. DC converter circuit3401is configured to receive DC input voltage3409. In various embodiments, DC input voltage3409may correspond to any of DC voltages3205A-C, or voltage portions3303A-C. DC converter circuit3401is further configured to generate current3410in primary coil3407included in transformer3402using DC input voltage3409and based on control signals3414. In some embodiments, current3410is an alternating current, and to generate current3410, DC converter circuit3401may be further configured to switch the polarity of DC input voltage3409relative to the terminals of primary coil3407in order to change the direction of current3410through primary coil3407. In various embodiments, a frequency of such switching may be based on at least one of control signals3414. In various embodiments, DC converter circuit3401is magnetically coupled to output circuit3419by transformer3402. Since the DC converter circuit3401is coupled magnetically to output circuit3419, no current can flow between DC converter circuit3401and output circuit3419thereby galvanically isolating the two circuits. As current3410flows in primary coil3407, a time-varying magnetic field is generated by primary coil3407. The time-varying magnetic field induces current3411in secondary coil3408of transformer3402. It is noted that due to the time-varying nature of the magnetic field, current3411may also be an alternating current. To enhance the inductive coupling between primary coil3407and secondary coil3408, the respective windings of primary coil3407and secondary coil3408may be wound around a common core of ferrous material. To provide additional granularity for the level of transmit voltage3108, transformer3402may be used to change the value of DC output voltage3413relative to DC input voltage3409. By adjusting the number of turns (or “windings”) of primary coil3407relative to the number of turns of secondary coil3408, the magnitude of current3411can be adjusted, either up or down, relative to the magnitude of current3410. For example, if the number of turns of secondary coil3408is greater than the number of turns of primary coil3407, then the magnitude of current3411will be greater than the magnitude of current3410. Different values of current3411can result in different values of DC output voltage3413. Since current3411is an alternating current, it must be converted to a DC voltage (or “rectified”) before it can be used by output voltage generator circuit3404. Rectifier circuit3403is configured to generate internal supply voltage3412using current3411flowing in secondary coil3408. In various embodiments, rectifier circuit3403may be implemented with multiple diodes to maintain a charge on a load capacitor in order to generate internal supply voltage3412. Output voltage generator circuit3404is configured to generate DC output voltage3413using internal supply voltage3412and based on control signals3415. In various embodiments, DC output voltage3413may correspond to any of output voltages3206A-C or load voltages3304A-C. Output voltage generator circuit3404may, in some embodiments, include inductive choke3418, which may be used to couple one instance of converter circuit3400to another instance of converter circuit3400as depicted in the embodiment ofFIG.72. In various embodiments, output voltage generator circuit3404may be implemented using a buck converter circuit or any other suitable circuit. Control circuit3405is configured to generate control signals3414. Such signals may include timing and enable signals for DC converter circuit3401. In various embodiments, control circuit3405may be configured to generate control signals3414using external communication signals3417and communication signals3416. In various embodiments, external communication signals3417may be sent to and received from another sub-converter circuit or a master control circuit included in a power transfer system. It is noted that the transmission of external communication signals3417and communication signals3416may be performed using optical circuits to provide electrical isolation between control circuit3405, control circuit3406, and any external control circuits. In various embodiments, control circuit3405may be implemented using a processor configured to execute software or program instructions, a microcontroller, other suitable state machine. Control circuit3406is configured to generate control signals3415, which may include timing and enable signals for output voltage generator circuit3404. In various embodiments, control circuit3406may be configured to generate control signals3415using communication signals3416received from control circuit3405. Control circuit3406may also be configured to send information regarding the operation and status of output voltage generator circuit3404to control circuit3405via communication signals3416. In various embodiments, control circuit3406may be implemented using a processor configured to execute software or program instructions, a microcontroller, other suitable state machine. Turning toFIG.75, a flow diagram depicting an embodiment of a method for operating a DC power transfer system is illustrated. The method, which may be applied to various DC power transfer systems including DC power transfer system3400, begins in block3501. The method includes receiving, by an input circuit of a given converter circuit of a first plurality of converter circuits, a DC input voltage from a renewable energy source (block3502). In some embodiments, the method further includes generating, by a plurality of photovoltaic panels, the DC input voltage. The method also includes generating, by an output circuit of the given converter circuit that is galvanically isolated from the input circuit, a second plurality of DC output voltage based on the DC input voltage (block3503). In various embodiments, generating the DC output voltage includes inducing, by the given converter circuit using the DC input voltage, a first current in a primary coil of a transformer included in the given converter circuit. In such cases, the method also includes generating, by the given converter circuit using a second current in a secondary coil of the transformer, the DC output voltage. In various embodiments, the second current in the secondary coil is based on the first current in the primary coil of the transformer. In some embodiments, the method may further include inducing the second current in the secondary coil based on the first current, a first number of turns on the primary coil, and a second number of turns on the secondary coil. The method may, in various embodiments, also include rectifying, by the given converter circuit, the second current to generate an internal supply voltage. In such cases, the method may further include generating, by the given converter circuit, the DC output voltage using the internal supply voltage. The method further includes respective DC output voltages from the first plurality of converter circuits to produce a transmit voltage (block3504). In some embodiments, the method includes adding the respective DC voltages to produce the transmit voltage. In various embodiments, coupling the first plurality of converter circuits includes coupling a first output of a first converter circuit to a particular node using a first inductive choke, and coupling a second output of a second converter circuit to the particular node using a second inductive choke. The method also includes heating a thermal storage medium by a heating element using the transmit voltage (block3505). In some embodiments, the method also includes receiving, by a second plurality of converter circuits coupled in series, the transmit voltage. The method may further includes generating, by the second plurality of converter circuits using corresponding portions of the transmit voltage, a plurality of DC output voltages, and combining the plurality of DC output voltages on a common power bus. The method concludes in block3506. Vehicle Charging Applications The above described DC/DC converter can be used for a DC vehicle fast charging application. This example circuit illustrates how it is possible for a standard 500 MAC cable to transport 2MW. Existing charging stations are connected to AC grid and either have their own substation or are connected to a bigger substation at 5060 Hz and low voltage. To pull 2MW, a very high current is required (4,000 amps) exceeding the limits of the grid capacity. By being able to transfer power using DC allows 1-2 MW power transfer at a much lower current allowing battery charging in 10-15 minutes to 80%, similar to a gas station stop. The DC/DC converter shown above may allow this high-speed DC charging. This structure uses multiple PV array microgrids as input, for example, and the DC/DC converters shown can provide high power and economical charging stations. Additionally, the charging station may also include on-site storage of the PV generated power using standard cabling. Thus, relatively small conductors at substantial voltage can be used to power a set of charging ports that can operate independently or in parallel. Power Transportation Applications If a PV panel connected with an inverter that is converting to AC and using a transformer to step up to a higher voltage to transfer it over a distance, then at the destination such as a charging station, battery or storage system, there is a transformer or some sort of rectifier. When such a system is running at peak solar capacity, the losses of the inverters and the transformers and the energizing losses of that AC system the eddy current and the inductive losses add to just under 90 percent efficiency. However, when the system is running at low power, the losses remain similar and the net efficiency drops substantially. Conversely, when doing a DC based system using the DC/DC converters described herein, losses are significantly lower since inductive or eddy current losses are not present in DC and ohmic resistive loads are lower. Thus, the efficiency increases slightly at low loads. Thus, these chained DC/DC converter systems can have applications in fields such as power transportation, vehicle charging, customer applications, solar fields connected to lithium battery systems among others, including a thermal storage system. This may significantly reduce ohmic losses in solar fields because wiring would be running at higher voltage and may reduce ohmic and AC losses between solar fields and batteries or solar field batteries and charging stations. Many microgrids will have these same issues because reliability of that microgrid and its efficiency change if its frequency is decoupled from the main grid. The DC/DC converter designs and implementations create the opportunity to run a fully DC microgrid, particularly at high voltage. For example, a 25 kV DC microgrid around a site and solar facilities can mean batteries can run at ultra-high efficiency. Some loads may be directly DC connected and some loads may be connected via inverters designed for power point loads. There may also be gateway inverters or rectifiers that gateway to an AC grid but the microgrid is not phase locked to the grid would mean that grid instabilities can't take it down. The value of 25 kV is just provided as an example, and other values may be used instead. With AC systems, there is a need to energize all the passive equipment and transformers thus circulating a lot of reactive energy, and transferring AC over distances can additionally incur losses with line impedances and power bouncing. DC power sharing over medium distances can be done very effectively using this DC/DC converter design, may enable more effective energy storage, more efficient energy transportation, using medium voltage DC for example up to 50 miles. Further, the DC/DC converter design eliminates the transformers and allows building that voltage by scaling them in series, which can be essentially lossless. This is made possible by each cluster being fully galvanically isolated, with two separate controllers (master/slave control). Further, there may also be top level-level power management to prevent excessive voltage rise in the main conductor if power demand on the load drops. In addition to the controller in each device (DC/DC converter) there may also be one overall controller that will be in charge of those conversions and conversion stages to set limits to those devices and how they can behave (limit power; limit current; limit voltage) to set boundary conditions. Thus, voltage sharing can be based on the idea of power sharing because if sharing power is started, then logically the voltage will be shared across those devices and the system will experience the same voltage drop on the input, same voltage drops on the output. The high voltage DC/DC conversion allows for very high efficiency connection of solar fields with suitable distance to loads such as a heated brick energy storage unit that can be coupled to electrolyzers and used for electric vehicle charging. Further, the system could have integrated hydrogen production and electric power generation from hydrogen and further have integration of lithium-ion batteries. The system can also be coupled to drive desalination to produce a completely off-grid facility or military base that is self-powering for its domestic loads, its heat loads and its vehicles. IV. Industrial Applications The above-described thermal energy storage system provides a stable output of heat from electrical energy that may be supplied from a renewable source. The stable output of heat may be provided to various industrial applications, to address art problems, as explained below. The ultrahigh temperatures capable of a radiatively heated thermal energy system100allow for application in a wide range of industrial processes. In particular, for processes that require ultrahigh temperatures, for example in glass production and metallurgical applications, such a high temperature thermal energy storage system powered by renewable energy provides the possibility of operating entirely or in large part from renewable energy around the clock, providing a path toward zero carbon processes. A. Material Activation 1. Problems to be Solved Cement production is one of the largest sources of global carbon emissions, responsible for as much as 8% of global CO2emissions. The carbon emission from cement production, however, has been growing more quickly than fossil fuel production. The unmet need to decarbonize the manufacture of cement is thus becoming even more of a critical requirement to achieve reductions in global CO2emissions in order to stabilize Earth's climate. Cement is typically made from limestone and clay (or shale). These raw materials are mined, then crushed to a fine powder. The blended raw material (“raw feed” or “kiln feed” or “meal”) is heated in a rotary kiln where the blended raw material reaches a temperature of about 1400° C. to 1500° C., e.g., 1400° C. to 1500° C. In its simplest form, the rotary kiln is a tube that may be, for example, 200 meters long and 6 meters in diameter, with a long flame at one end. The raw feed enters the kiln at the cool end and gradually passes down to the hot end, then falls out of the kiln and cools down. In the initial stages at lower temperature (e.g., 70-600° C., and more specifically, 70-350° C.), free water evaporates from the raw feed, clay-like minerals and dolomite decompose into their constituent oxides, producing calcium carbonate, magnesium oxide and carbon dioxide. Over intermediate temperatures (650-1050° C.), some calcium carbonate reacts with silica to form belite (Ca2SiO4) and carbon dioxide. Remaining calcium carbonate decomposes to calcium oxide and CO2. At the hottest regions (1300-1450° C.) of the kiln, partial melting takes place and belite reacts with calcium oxide to form alite (Ca3O·SiO4). The rotary kiln is used in more than 95% of modern world cement production. The material exiting the kiln, referred to as “clinker”, is typically composed of rounded nodules. The hot clinker falls into a cooler, which may be designed to recover some of its heat, and cools to a temperature suitable for storage (or is directly passed to the cement mill where it is ground to a fine powder). Gypsum or other materials may be ground together with the clinker to form the final cement product. The hottest end of the rotary kiln heated by a combination of recovered heat from the hot clinker and burning of fuels is at the exit of the clinker. The heated gas travels in a direction counter to the clinker process. The exhaust gas exits where raw feed enters the rotary kiln. A majority of cement production uses a separate precalciner to increase production and efficiency for a given cement kiln. The precalciner is a suspension preheater which allows some of the energy required for the process to be burned at its base. The precalciner allows more thermal processing to be accomplished efficiently in the preheater, greatly increasing throughput for a given sized rotary kiln tube. Depending on the system design, a precalciner can output feed that is 40-95% calcined, at high end, leaving the primary role of the rotary kiln for sintering. The input gas to the precalciner may be preheated by the hot air recovered from cooling clinkers, in addition to the fuel burned. The hot gases exiting the top of the precalciner are often used for drying raw materials. This process, however, tends to be intermittent, thereby wasting heat when the rawmill is stopped. In some cement production systems, a bypass between the kiln inlet and the precalciner may be installed to extract the dust containing materials potentially damaging to equipment and to final product quality. The collected material, referred to as the cement kiln bypass dust (CBPD), can be approximately 2%, e.g., 2%, of the total clinker production by weight and consists primarily of calcium oxide, a key component of clinker, as well as salts such as KCl and other contaminants. CBPD is usually landfilled at a cost. CBPD mainly includes already decarbonized calcium oxide. A recent study has shown that temperatures of approximately 900-1200° C., e.g., 900-1200° C., can transform CBPD into valuable clinker components such as belite, mayenite, alite and ferrite at lower temperatures than in the rotary kiln (assisted by other components in CBPD while vaporizing and removing contaminants such as KCl) leaving behind a cementitious product free from a majority of the undesired contaminants which are initially present. In a traditional cement plant, fuel and oxygen are fired to provide heat into the clinker kiln. This fuel may be in the form of solid media such as refuse or coal (or may be natural gas) introduced along with combustion air into the kiln. At the outlet of the kiln, a stream of hot combustion gases provides a portion of the heat used to preheat the meal and then calcine the meal; the balance of that heat may be supplied by combustion of a fuel and/or heat recovered from hot clinker cooling. The process of calcination consumes about 20-75%, e.g., 20-75%, of thermal energy from fuel depending on precalciner design and operation. The term “calcination” broadly refers to a process in which a solid chemical compound is heated to a controlled, high temperature in a controlled environment in the presence of little to no oxygen to remove impurities and/or to incur thermal decomposition to a desired product. The term calcination has traditionally referred to a process for decomposing limestone (or calcium carbonate) into quicklime (calcium oxide) and carbon dioxide. This reaction is widely used in industry given that limestone is an abundant mineral and that quicklime is used in the production of cement, mortar, plaster, paint, steel, paper and pulp as well as in the treatment of water and flue gases. Other calcination processes include the dehydroxylation (i.e., removal of crystalline water) of gypsum used in producing building materials and other products and the dehydroxylation of alumina used in producing aluminum metal and other products. Another calcination process is the dehydroxylation of clay minerals, which may be used for the activation of clay for use as a supplementary cementitious material (SCM) in a cement mixture, such as alongside Portland cement. Clay mineral activation differs from its limestone counterpart in that the reaction releases water (—OH groups) instead of CO2. Different calcination reactions require different operating conditions (e.g., temperature, environment compositions, etc.) to expose minerals to heat and drive calcination. Over time, different designs have been developed, including shaft furnaces, rotary kilns, multiple hearth furnaces, and fluidized bed reactors. Many associated processes have also been developed including internal radiant heating via fuel combustion within a kiln or reactor, internal convective heating via hot gas flow within a kiln or reactor, or external heating of a kiln or reactor. These traditional modes are referred to as soak-calcination processes, given that the material takes several minutes to hours in the reaction chamber to become fully activated. Flash calcination is another approach, which is more rapid than the soak process, and takes place in a reactor that uses gases at velocities and temperatures creating gas-particle interactions including entrainment and suspension, so as to drive effective heat transfer and encourage chemical reactions. Systems using this principle commonly introduce a gas that has been heated via combustion of a fuel (including direct exhausted combustion products) and/or a gas that may be heated from cooling the products of calcination (or recovered from other heat sources, at the bottom of a reaction chamber in an up-flow configuration). The gas temperature may commonly range from 600° C. to 1100° C. In one implementation, raw clay material to be processed is finely divided and is fed into a chamber above the hot gas injection point. Upward flowing hot gases interact with raw material and may suspend the raw material through the chamber where the particles are quickly heated by the flowing gases. Additional sources of heat may be incorporated within (or without) the chamber, including fuel combustion devices or additional hot gas introduction ports, to maintain a desired temperature profile or ambient gas composition. As the material exits the chamber, it has been heated to the desired state of calcination (or activation). The gas composition within the chamber may be selected to perform a function of controlling the quality of the product. For example, oxygen may be excluded or there may be a reducing atmosphere zone for quality control of the product. The material to be processed may contain iron that will become oxidized in non-reducing environments and cause the product to change color which may not be desired. This atmosphere reduction zone may be enforced via injection of reducing gases or supplied via supplemental burners in which any oxygen in the air is reduced via injected fuel. After heating and calcination, the material is then rapidly cooled, often by air in cooling cyclones or another form of air quench. Water can also be used as a cooling fluid in certain processes. The product is cooled to 100° C. to 200° C. Some attempts have been made to analyze clay calcination in gas suspension heaters in order to determine the effect of operating conditions. In one example, a kaolinite particle feed was added above a burner and passed through the chamber with and without supplemental burners along the channel. Convection was the dominant form of heat transfer in the process where an ideal gas supply temperature was about 900° C., e.g., 900° C., without supplemental burners. In these approaches, internal resistive heaters cannot be used to replace a burner in the calciner. The technical reason is that it is extremely hard to heat the large gas volume needed for gas suspension purely via resistive heaters, as the space and cost required would be too large. Additionally, the resistive heaters may experience degradation due to the particulate matter present in a calcination process. 2. Calciner Heated by Electric Power from Thermal Energy Storage The present disclosure describes example implementations that involve the replacement of fired fuel and/or hot gas generators with a novel high-temperature thermal energy storage (TES) system. Example implementations cover multiple embodiments of a material activation system with different degrees of integration into material activation processes, which may be used to produce quicklime in some implementations or other activated materials such as activated clay or alumina. Example implementations relate to a novel TES system's integration with a material heating system using any of a variety of calciner/kiln configurations. In some implementations, the integration could be with an existing plant where the TES system and all process modifications are retrofitted to an existing material activation system. In other implementations, a new material activation system is built in which the material heating system is designed around the thermal energy storage system. In one implementation, a thermal storage system may be used as a replacement for existing hot gas generators in material activation processes. Accordingly, one or more thermal energy storage arrays may provide hot gas as the primary heat transfer fluid for convective heat transfer demands of the material heating system. These demands may include the drying, preheating, cooling, or calciner heating and may be filled via direct tie-in to a thermal storage unit. Gas of any composition may be either recirculated through the TES system after use or fanned in from ambient air, to be used at higher temperatures in the process. In various implementations, the material activation system includes the above-disclosed thermal energy storage system transferring heat into air, into CO2, into CO2with a small air fraction, into gases which vary in composition with time (e.g., a dominant gas with a second gas such as air or O2being present at a different concentration during some fraction of operating hours), and/or into gases arising from an interconnected industrial process, such as mineral calcination. In a further implementation, a small amount of hydrogen or other reducing gas may be included with the carbon dioxide. Example implementations may also include provisions for tolerating, separating, and/or removing entrained particulate matter in a structure such that periodic cleaning maintains long-term performance of the TES system. In some implementations, carbon dioxide is used as the heat transfer fluid to deliver heat into the material activation process and is then combined with additional carbon dioxide released by calcination. Accordingly, no carbon dioxide separation processes are required (other than condensing any water which results from the combustion of fuel). In another example implementation, thermal energy storage systems employed in the process can heat multiple different gases or gas mixtures for use in the material activation system. Example implementations as disclosed herein can be considered with regard to two subclasses. In the first subclass, a TES system directly supplies heat in the form of a heated fluid (such as air, CO2, gaseous combustion products, or a combination of multiple gases), replacing a combustion-based hot gas generator for some or all of its typical applications in a material activation process. These applications include, but are not limited to, drying raw material (such as limestone, clay, bauxite, or raw meal), aiding in reactor start up and cool down (getting a reactor to auto ignition temperature (600° C. to 1500° C.)), and preheating raw material (such as limestone, clay, bauxite, raw meal, or a mixture) to desired reactor operating conditions (400 to ° 1000° C.). Implementations in this first subclass may apply to combustion-based material heating systems such as fuel-fired calciner/kilns, where all auxiliary heat needs other than the burners in the calciner/kiln are provided by thermal energy stored in the TES system. The second subclass is a more highly integrated process in which the TES system is used to supply thermal energy/heat in the material activation process and combustion may be used in moderation (if at all) to provide suitable atmosphere control for the desired reaction. Example implementations include different process configurations of the TES system integration. In various implementations, one or more high temperature TES units supply heat directly or indirectly to the calciner or kiln reactors as well as dryers and pre-heaters. In implementations that employ direct heat transfer, the fluid used as the heat transfer medium in the TES system is being supplied directly to the raw material in the calciner and then recirculated back to the TES system after coming into direct contact with the raw material. In implementations that employ indirect heat transfer, the fluid used in the TES system does not come into direct, physical contact with the material in the material heating system. Rather, in some implementations, the fluid in the TES system is used to transfer thermal energy via a heat exchanger into a secondary fluid that comes into contact the material. In other implementations, the fluid used in the TES system may indirectly heat the raw material without the presence of a secondary fluid by heating the walls of the calciner or kiln reactor system, with the heated walls transferring heat to the raw material on the other side of the wall via conduction and radiation. This “indirect” heating mode of thermal storage operation can also be used in applications other than calcination or kiln reactors, including but not limited to biomass drying or food processing. The secondary fluid may be in the liquid state in some implementations. There is also a combination of direct and indirect heating modes for the TES system fluid where the higher temperature TES system fluid exchanges heat indirectly with a secondary fluid (with a gas-to-gas heat exchanger, for example) and additionally raises the temperature of the secondary fluid stream via direct injection by a bypass configured to inject a portion of the higher temperature fluid from the TES system into the secondary fluid provided to the material heating system. This can be useful for atmosphere control within the material heating system (and within the TES system as well in some implementations). The secondary fluid mixed with some of the TES fluid is then exposed directly to the raw material of the material activation process to supply heat. After supplying heat, this secondary fluid may be treated to remove undesired components that were added to the stream via contact with the raw material such as water, undesired emissions (SOx, NOx, CO, etc. . . . ), and particulate matter. Some or all of this treated secondary fluid may be used to fill other auxiliary heat demands such as drying or preheating or treating or cooling demands (oftentimes, raw material must be cooled after reactions in the calciner/kiln reactor zones). Some or all of the secondary fluid may be returned to the heat exchanger where the stream can be reheated. In some implementations, a small portion of the heat may also be supplied via supplementary combustion in the material activation process. This may raise the temperature of the gaseous heat transfer stream depending on the specific operating conditions associated with the combustion. Generally, the fuel would be combusted ‘fuel rich’ meaning that there is more fuel than stoichiometric oxygen in the reaction. The primary reason for this fuel rich combustion is atmosphere control as clay, for example, requires slightly reducing systems to not oxidize the iron in the clay and hence prohibit ‘color change’. For example, the amount of oxygen may be reduced, and the iron in the clay may be reduced. The TES system may, however, require slightly oxidizing conditions for nominal operation. The supplementary combustion would remove the small amount of oxygen and create color reducing conditions for the clay. The final product to be output is activated clay, which is used instead of clinker to make cement. There are several relevant calcination processes that are covered by the material activation system described herein. Different processes often demand different operating conditions (temperature, pressure, residence time, gaseous composition in the calciner, etc. . . . ) although various components of the material activation system may be shared amongst different processes. FIG.76illustrates an example implementation of a material activation system76010described herein. As shown, material activation system76010includes a TES system76020, a material heating system76030, and a recirculation system76040. TES system76020includes one or more thermal energy storages76022. Material heating system76030includes a pre-heater/precalciner76032, kiln/calciner76034, atmosphere reduction system76036, and a cooling system76038. In other implementations, material activation system76010may include more (or fewer) components than shown; components may also be arranged differently. As discussed in greater detail in other sections, TES system76020is configured to store thermal energy derived from an energy source. In some implementations, this energy source is a renewable energy source (e.g., wind, solar, hydroelectric, etc.) or some other form of variable energy source. Thermal energy storages76022within TES system76020may include heating elements configured to heat a storage medium using electricity from the energy source. These heating elements may include any of the various examples described herein including, for example, thermal resistors, ceramic resistors, etc. The storage medium may include any of various examples described herein such as brick, stone, etc. To facilitate extraction of thermal energy from the heated storage medium, blowers may be used that are configured to heat a non-combustive fluid (e.g., carbon dioxide, nitrogen, air, or others discussed previously) by circulating the non-combustive fluid through the heated storage medium. As noted above, the use of non-combustive fuel stands in contrast to prior combustion-based systems that rely on a combustive fluid (e.g., natural gas, propane, methane, etc.) to provide energy. In various implementations, TES system76020is configured to provide this circulated non-combustive fluid to the material heating system to facilitate activating a raw material. In some implementations, TES system76020is configured to provide the circulated non-combustive fluid to the material heating system at a temperature within a range of from 600° C. to 1100° C.; however, the fluid may have a different temperature in other implementations. Material heating system76030, in general, is configured to apply thermal energy to a raw material to produce an activated material. Techniques described with respect to the material heating system may be employed with respect to any of various material activation processes. As discussed above, in some implementations, material heating system76030is a calcination system configured to perform a calcination process that removes carbon dioxide from a supply of calcium carbonate to produce calcium oxide. In other implementations, material heating system76030is configured to perform a dehydroxylation process (i.e., use of heat energy to remove molecularly bound water) that removes hydroxide from clay minerals to produce activated clay. In other implementations discussed below withFIG.83, material heating system76030is configured to implement a single stage of the Bayer process that includes a calcination step which transforms bauxite to produce aluminum oxide as the activated material. In various implementations, material heating system76030is configured to receive thermal energy derived from the non-combustive fluid provided by TES system76020. As previously discussed, the provided fluid may be used in a direct heating implementation in which material heating system76030brings the provided fluid into contact with the material. The provided fluid may alternatively be used in an indirect heating implementation in which a heat exchanger is configured to receive the circulated non-combustive fluid from TES system76020, transfer heat from the circulated non-combustive fluid into a second fluid, and provide the heated second fluid to material heating system76030for applying the thermal energy to the raw material. In a mixed fluid implementation, material activation system76010may further include a bypass configured to inject a portion of the circulated non-combustive fluid received from TES system76020into the second fluid provided to material heating system76030. In some implementations in which TES system76020is unable to supply enough thermal energy for material heating system76030, material activation system76010may further include a burner (or some other combustion based energy source) configured to supply combustion energy to the material heating system in addition to the thermal energy supplied by the TES system. Pre-heater76032is configured to apply thermal energy derived from the circulated non-combustive fluid to heat the raw material to a first temperature before providing the heated raw material to the kiln for heating to a second temperature. In some implementations in which the Bayer process is performed, pre-heater76032is configured to implement a first stage of the Bayer process that includes heating the bauxite to a temperature within a range from 300° C. to 480° C. and at a first pressure within a range of 6 bar to 8 bar. In the illustrated implementation, the thermal energy applied by pre-heater76032is received from TES system76020; however, in other implementations, some or all of this thermal energy may be obtained from an exhaust fluid output by kiln76034. Kiln76034, in various implementations, is the primary component responsible for applying thermal energy to a raw material to produce an activated material. Kiln76034may be implemented using any suitable techniques such as flash calcination, rotary kiln, or others discussed above. For example, in some implementations, kiln76034is configured to apply the received thermal energy by injecting the raw material via a first inlet of the kiln and injecting, via a second inlet underneath the first inlet, the heated non-combustive fluid in an up-flow configuration that suspends the raw material within the kiln in order to more efficiently heat the material. In one implementation in which the Bayer process is performed, kiln76034is configured to implement a second stage of the Bayer process that includes elevating a temperature of the bauxite within a temperature range from 750° C. to 950° C. and a second pressure lower than the first pressure. Atmosphere reduction system76036is configured to reduce an amount of oxygen in contact with the activated material produced in kiln76034before the material is cooled. In implementations that produce activated clay, the removal of oxygen may prevent the activated clay from becoming discolored due to oxidation of any iron present in the clay. In one implementation, atmosphere reduction system76036includes a burner that combusts a rich fuel mixture to produce carbon monoxide to absorb any excess oxygen. In some implementations, atmosphere reduction system76036may not be used as either the activated material may not react with oxygen or the fluid in contact with the material may already include a low oxygen content, such as in a direct heating implementation in which carbon dioxide is used as the non-combustive fluid. Cooling system76038is configured to receive the activated material of the material heating system and reduce a temperature of the activated material. Cooling system76038may employ any suitable techniques such as using cooling cyclones or other techniques noted above. In some implementations, the exhaust fluids are collected from cooling system76038for recirculation by recirculation system76040. Recirculation system76040, in general, is configured to recover thermal energy that has not been consumed by the material activation process. In the illustrated implementation, this recovery includes recirculating exhaust fluid output from material heating system76030to TES system76020. In implementations that produce carbon dioxide as a biproduct of the material activation process, recirculation system76040may recirculate produced carbon dioxide to TES system76020for use as the non-combustive fluid. In various implementations, recirculation system76040includes a filter configured to remove particulate from the exhaust fluid prior to the exhaust fluid being provided to the TES system. As noted above and discussed in more detail below, in some implementations excess thermal energy may be used for various other purposes. For example, material activation system76010may include a steam cycle system that includes a heat exchanger configured to produce steam from thermal energy recovered from material heating system76030and a steam turbine configured to generate electricity from the produced steam. FIG.77illustrates another implementation76050of a material activation system using electrically heated thermal energy storages R1-R4. The overall process uses carbon dioxide as the principal heat transfer medium through the kiln/calciner and precalciner. No air, nitrogen, or excess oxygen is introduced into the kiln, and as a result, the CO2that is evolved by the calcination reaction is mixed with CO2that was supplied as the process heat carrier and any CO2produced by fuel combustion, so that the gas stream at point D, the exit of the preheater calciner unit, is nearly pure CO2, potentially with some water if fuel is combusted. This CO2stream in part or whole, is optionally used to dry raw materials, increasing its moisture content and is partly cooled and compressed/pumped away, and partly recirculated to the thermal energy storages R1 and R2 to carry further heat into the process. Each thermal energy storages R1 and R2 accepts a CO2stream at a lower temperature and heats that CO2stream to a very high exit temperature by passing it through a series of conduits in solid material which has been heated by electrical energy (e.g., the “storage media core”). Thus, a closed carbon dioxide cycle heat transfer is provided. By choosing appropriate materials for heating elements and heat storage media, the heat transfer gas may be selected among a wide range of compositions, including but not limited to any of, or any mixture of, air, N2, O2, CO2, H2O, and other gases or gas mixtures. Optionally, a minimum level of oxygen may be included, depending on the composition of the resistive heating element. In addition to carbon dioxide as explained above, in combination with a fraction of hydrogen gas or other reducing gas, nitrogen may also be used. A benefit of using nitrogen is that it is inert and the primary gas present in atmospheric air. Certain gases interact with metallic heaters in such a manner as to limit their operating temperatures. Heating materials which form protective oxide scales are compatible with the continuous or intermittent presence of oxygen. Other heaters, including conductive ceramics and encapsulated heaters, enable higher operating temperatures and selection of atmospheres which are oxidizing or reducing. The CO2stream is passed directly through the thermal energy storage as the principal heat transfer fluid. The solid media is heated by intermittently available renewable or grid electricity, and relatively continuously delivers a high temperature stream of CO2which may be at 1000° C. or higher temperature and may deliver a significant fraction or all of the process energy required by kiln76052and preheater/calciner units. Each “unit” referred to may include one or multiple units to meet charging, discharging or other requirements. The thermal energy storage may not deliver high enough temperature or energy to the kiln76052. The combustion of some fuel may supplement the energy flow and boost the temperature to what the process requires. Therefore, the heating process may optionally be a hybrid of heat derived from renewable electricity and heat derived from fuel combustion. In one example implementation, this fuel combustion directly releases its combustion gases into the kiln, avoiding the expense of heat exchangers. Those combustion gases include principally or only carbon dioxide and water because an air separation unit has delivered a relatively pure stream of oxygen. In some example implementations, a stoichiometric or near stoichiometric amount of oxygen may be used in burning of the fuel to create a stream of syngas (i.e., synthetic gas) containing a desired amount of carbon monoxide. The produced syngas may be used in a separate water gas shift reactor system to produce hydrogen and carbon dioxide, which can be used directly as fuel or separated and productized. Accordingly, nitrogen is not introduced into the gas stream flowing through the kiln, which may yield an additional benefit of avoiding nitrogen oxide formation at high temperature and making obsolete the non-catalytic reduction requirement (i.e., injection of ammonia solution into the kiln), avoiding unnecessary heating of a bystander gas such that a CO2separation technology is not needed in the process to separate CO2from nitrogen. The combustion oxygen stream is optionally preheated to high temperatures, such as 800° C. or higher, by a thermal storage unit R4 in which oxygen is directly flowing through the thermal storage media core. Optionally, the oxygen stream may be mixed with recycled flue gas (predominantly CO2) to control the flame temperature and heat output of the combustion process. In another example implementation, the oxygen stream is mixed with both or either of flue gas (predominantly CO2) and/or gaseous fuel before entry into the kiln combustion system. By tuning the quantity of CO2mixed into the fuel stream, the heating profile can be controlled in a way to adjust, for example, fuel consumption, product production, quality and system configuration to allow retrofitting of existing kilns. The fuel, whether methane, propane, hydrogen, or other fuel, optionally combined with recycled CO2stream, may be preheated by a separate thermal energy storage R3 in which the fuel gas flows directly through the thermal energy storage core. This preheating allows the heat released by combustion to deliver only the high temperature heat, with lower temperature heat needed to heat the oxygen and fuel provided by captured thermal energy. The construction materials used in thermal energy storages R3 and R4 may be the same as those in storages R1 and R2 or may be different so as to tolerate the gas composition(s), temperature requirement or to improve performance, cost, durability, chemical interactions or other parameters. In one implementation, the result of the foregoing example operations is that between storage R1 and combustion of fuel and oxygen optionally heated by storages R3 and R4, high temperature CO2streams deliver the kiln heat required by the kiln reaction steps. The kiln exhaust gas stream is comprised principally of CO2(potentially with H2O from combustion, if any). This gas stream is optionally combined with another superheated CO2stream carrying high temperature heat at point C and introduced into the calcination and preheating process76054, heated by thermal energy storage R2. In the calcination process, additional CO2is released, and thus a higher volume of CO2flows at D. The gas stream at D may be cleaned of particulate matter by, for example, a cyclone separator and/or ceramic filter. The gas stream is divided, with one portion returned to thermal energy storages R1 and R2 where it is reheated to continue to deliver heat into the process, and another portion partially cooled and extracted as captured CO2. In one implementation, a control system matches the rate of CO2extraction and compression to the rate of CO2production in the calciner. That control system may use measurements of the relative gas pressure in the various process units or other ordinary means to control the rate of gas extraction. Two heat exchangers H1 and H2 are shown which may cool the CO2by releasing heat to the environment or may cool the CO2and use the heat for another purpose, for example drying of raw material or heating input CO2stream for R2. This example operation allows for energy recovery even when the rawmill is not operational, as they tend to run intermittently to ensure a surplus of raw material to keep the kiln running continuously. Alternatively, a separate TES system (not illustrated) may be coupled to the rawmill operation such that the drying process is powered from the thermal energy storage. The thermal energy storage may be charged convectively by exhaust at D or electrically. The cooled CO2may be compressed, captured and stored or used for another purpose. Because the stream almost entirely consists of CO2and potentially water, water removal through a condenser would produce a pure stream of CO2ready for compression. Optionally, a relatively inexpensive CO2purification unit may be used. In comparison, MEA absorption requires a considerable amount of energy for regeneration and fans and pumps. FIG.78illustrates an example implementation76060of a kiln76062and precalciner R decoupled system. The hot exhaust air from the rotary kiln is decoupled from the preheat/precalciner inlet. The heat recovered from the cooler for the hot clinker may or may not be fed into the precalciner. In another optional example implementation, thermal storage system R2 or another heat system provides heat for the treatment of cement kiln bypass dust (CBPD) to increase product yield, reduce carbon emission and reduce costs associated with landfilling or otherwise disposing of the material. The separated or addition of salts may be beneficial as additives to the main material stream to lower the processing temperatures, reducing the energy and temperature requirement to form the desired product, potentially further reducing the need for fuel fired heat topping and allowing renewable energy to power a larger fraction of the cement production process. FIG.79shows an implementation76070that uses waste heat from cement production process exhaust to provide economizer heat in a thermal cycle power generation system. As shown, an electrically heated thermal energy storage R5 may produce superheated steam, supercritical carbon dioxide, or another heated working fluid driving a turbine power generation cycle. An electrically charged thermal energy storage unit delivers a high pressure, high temperature stream—superheated steam, carbon dioxide, or another working fluid—driving a turbine which powers the generation of some or all of the electricity used at the facility relatively continuously. The thermal generation cycle reject-heat flows to an air- or water-cooled condenser, and the cooled condensate or return gas is then pumped to high pressure. Heat exchangers H1 and H2, which capture heat from the carbon dioxide streams, may release heat into the feedwater or inlet gas stream for the power generation cycle, thus capturing that otherwise waste heat as a heat recovery economizer in the power cycle. In various implementations, that power cycle may be a simple steam turbine cycle, an organic Rankine cycle, a supercritical carbon dioxide (sCO2) cycle, or it may be a combined cycle power generation system, including a combustion turbine whose exhaust is captured to drive a second thermal cycle. In one example implementation, the combustion turbine is oxyfuel blown and its exhaust gas CO2is introduced back to the overall CO2cycle, eliminating any separate CO2emissions from the power generation. The thermal energy storage R5 may be integrated into that combined cycle as shown. In one example implementation, supercritical carbon dioxide is used as the working fluid inside the heat storage unit and can directly run a sCO2power cycle or be used for another application. The CO2stream extracted from the cement manufacturing process may be used for multiple purposes, including geologic sequestration, carbonation of supplementary cementitious materials, or as an element in the production of synthetic fuels. Another example implementation includes a steam cycle for continuous power generation and additional heat recovery. In such an implementation, hot air from the cooling cyclones or a screw heat exchanger in contact with the hot calcined product exchanges heat with pressurized, recycled water from the steam cycle and some makeup water. This cooled gas/air is either released to the environment, used in the drying part of the process, or introduced as cool gas in a TES system. The preheated water is turned into steam via heat exchange with a TES system. This may be the same TES system involved in the calcination process or a supplementary unit. The air side of this heat exchange is circulated back into the TES system to reduce waste heat. The steam is then expanded in a steam turbine, generating electricity for the plant. The steam downstream of the steam turbine may exchange heat one last time with air or gas for use in the drying process before being mixed with any feed water makeup, pressurized and recirculated in the cycle. FIG.80shows an integration76080of a solid oxide electrolyzer whose operation is maintained by heat stored in a thermal energy storage R6, and whose operation may be advantageously efficient by being maintained at beneficial temperature, with the thermal energy storage providing thermal energy that is absorbed in an endothermic electrolysis reaction. Such a solid oxide electrolyzer may electrolyze water to produce hydrogen or may co-electrolyze a flow of steam and carbon dioxide, such that its outlet products are carbon monoxide and hydrogen, or syngas. The relative flow of CO2and H2O may be so adjusted as to produce the desired proportions in the syngas of carbon monoxide to hydrogen. The desired syngas composition may also be attained by controlling the combustion and stoichiometry of the fuel fired inlet. The syngas may be used for a variety of purposes, including the drive of Sabatier or Fischer-Tropsch reactions to make various hydrocarbon molecules, or a water gas shift reaction producing H2which may be used as fuels or feedstocks in other industrial processes. The solid oxide electrolyzer (SOEC) may be integrated with thermal energy storage R6 in gas contact with the fluid flowing through the thermal storage core, where that circulating fluid is air. In one implementation, the SOEC may be swept by air at a higher temperature, such as 830° C., and the air exiting from the SOEC may be at a lower temperature such as 800° C. The heat in that air is then captured by a heat recovery unit to generate steam or heat another working fluid for another purpose. That heated fluid may for example be integrated into the electric power cycle previously described. The operation for the SOEC releases oxygen into the air sweep. To manage overall oxygen concentration, relatively cooler air coming from the heat recovery unit is partially released, and ambient make up air is partially drawn into the thermal energy storage. This released gas is oxygen enhanced air. This stream may be supplied to an air separation unit, an alternative feedstock to the air separation unit, storage unit or fuel firing units shown onFIGS.77through79as a means of mitigating their electric power consumption and improving their output. Hydrogen or oxygen produced may be stored in tanks or underground caverns for future use or sale. As shown inFIG.81, combustion-based approaches76100may be associated with implementations of a calcination process. In one implementation, the raw material, such as the clay minerals, is provided at76101. The raw material is fed to a dryer/crusher at76103. At76107, the crushed and dried clay is fed to preheat cyclones76107. At76109, the product that was fed through the cyclones and preheated with hot gas at76107is provided to a calcination chamber76109. The calcination chamber76109is heated with hot gas provided from a combustion chamber76113, which is provided by fuel from a burner76111. The gas steam may also be provided to the preheater cyclones76107, dryer/crusher76103and filter and exhaust stack76105. At76115, the product is reduced in a reducing zone76115, which may be powered by supplementary fuel76117. Then, the reduced product is provided to cooling cyclones76119, where ambient air76121is provided for cooling. An activated material, such as activated clay for making cement, is provided at76123. The foregoing approach is modified by the integration76150of a thermal energy storage system as shown inFIG.82. Elements having similar or same depictions asFIG.81are not repeated. More specifically, instead of using fuel to provide air via combustion, the thermal energy storage system76163provides hot gas heated by radiative heating from electrical energy. Thus, it is not necessary to use fuel for combustion. Accordingly, the above-mentioned problems associated with moisture from the combustion process may be avoided. Additionally, a baghouse filter76155is used as an output of the dryer/crusher76153, and the gas byproduct of the baghouse filter76155is provided to an exhaust stack76157and to the thermal storage system76163as an input. The byproduct gas from the cooling cyclones76169is also provided as an input to the thermal energy storage system76163. The structures and operations associated with the other features, such as the dryer/crusher76153, preheat cyclones76159, the calcination chamber76161, the reducing zone76165, the supplementary fuel76167, the cooling cyclones76169, and ambient air76171, are similar to those explained above with respect to the other approaches. In one implementation, the raw material, such as the clay minerals, is provided at76151. An activated material, such as activated clay for making cement, is provided at76173. As noted above, the TES system may be used to provide heat into the calcination step of the Bayer alumina process. Additionally, the heat inputs into other parts of the process may also replace fuel, including the fuel that is provided at the mine, at the lime kiln, and at the steam generator that provides energy to operate these modules. With respect to the calciner stage, art approaches perform calcination in two stages: a first stage at a lower temperature associated with a decomposer and steam separation to perform partial, and a second stage at a higher temperature than the first stage, but at a lower temperature than would be required if calcination was performed in a single stage. The first stage may be at a temperature such as 350° C., and the second stage may be in the range of 750° C. to 950° C. The two-stage calcination process provides energy efficiency advantages over a single stage calcination process. Similar to clay calcination, a fuel is provided as an input to the first calcination stage and the second calcination stage. The heat that is output from calcination may be provided for reading and waste heat recovery, with the remaining heat being expelled after water cooling via stack gas output. Conventional calcination involves heating the cooled, wet gibbsite to 950° C.-1100° C. to remove free and crystalline moisture in the gibbsite, which is derived from bauxite. Art approaches have used a rotary kiln or calciner using heat from combustion. According to some art approaches, the material first enters a high-pressure calcination step (e.g., the decomposer), for example at 6-8 bar and 300° C.-480° C., and removes all the free moisture (e.g., drying) and activates a significant portion of the gibbsite to alumina. These mechanisms produce water vapor as effluent. The partially calcined material passes through a pressure reducer to the lower pressure calcination stage. This occurs at ambient pressure and relatively lower temperatures of 850° C.-950° C. Fuel and air that is preheated in the cooling of the product material is combusted in a gas suspension calciner. The heat from the flue gas is further recovered by being passed into a steam generator/superheater where is exchanges heat with recycled steam from the first stage, recycled steam from other steps in the Bayer process, or makeup water to supply the first calcination step (or decomposer) with superheated steam. These approaches may have problems and disadvantages. For example, when steam is used as a heat transfer medium in calcination stage, it is necessary to account for the plant balance, as the extremely high mass flow of superheated high-pressure steam must be filtered and cleaned before recirculating to other areas of the plant. The theoretically more favorable heat balance from collecting high temperature moisture from the decomposer also translates to a more complex, integrated process. The large mass flow leads to art problems in supplying the correct quantity of superheated steam. The steam generator/superheater is a major area for concern, both from the thermodynamic and operating standpoint. Additional fuel must be fired in this step. Additionally, buildup in process equipment is one of the largest issues in the concept, as the recirculated steam often must be cleaned and filtered of particulate matter before interacting with the steam generator and superheater. To address these problems and disadvantages, the thermal energy storage system described above supplies heat to recirculating process steam, and may be integrated with heat recovery apparatuses to address art plant balance problems. For example, heat from the hot flue gases of the second gas suspension calciner may be utilized to supply a portion of the heat to either the thermal storage working fluid medium (e.g., gas-to-gas heat exchangers) or the process steam (e.g., gas to liquid heat exchanger). This will allow the plant greater flexibility in energy management as well as maintenance to fix solid buildup in heat transfer equipment. The thermal battery may be external to the plant and may either supply steam externally with an attached steam generator or supply steam indirectly, passing hot gases through existing or new heat exchangers replacing the duty of combustion gas products. In another example implementation, the thermal storage relates to a fully integrated process where the thermal batteries replace all combustion on site. This implementation includes the above-described approach, with supplying all or the majority of the heat to the second calcination stage. The temperature of the partially calcined material is brought to near ambient pressure (from the high-pressure stage 1) and put in direct contact with hot flue gases bringing the temperature to 850-950 C. This reduced temperature range allows the heat from fired fuels to be replaced by high temperature stored heat. In some example implementations, the primary working fluid of the thermal energy storage system would contact the material to be calcined. In other example implementations, this heating may occur indirectly, where the primary working fluid of the thermal battery does not directly contact the material. The hot gas would be blown through the calciner at sufficiently high velocities to achieve desired level of suspension and activation. The gas effluent would leave the chamber at a high temperature to be used in the steam generation and superheating of the process steam used in the first stage of calcination as well as any other steam needs in the system. As shown inFIG.83, a calciner process8300associated with aluminum production according to the example implementations has several modifications to prior approaches. The thermal energy storage8301provides a heat input to the second calcination stage8303. Thus, instead of using fuel to generate that heat, such as by combustion in other approaches, the heat is provided as hot gas from the TES system as explained above. A high volume of high temperature hot gas is provided as an input to the second calcination stage at its operating temperature. Thus, it is not necessary to provide preheated air from alumina cooling8311, as may be required in prior approaches. The output byproduct of the second calcination stage8303is slightly cooled gas that can be used for the heat recovery steam generator8307, instead of the additional fuel and air that may be present in the prior approaches. The steam output from the steam generator8307is provided to the first calcination unit8309at the temperature of the first calcination unit8309, which may provide the recycled steam flow and solids as in the prior art. Additionally, instead of expelling excess heat or waste heat from the steam generator as a set gas, the heat byproduct of the steam generator is the gas that has passed through a heat recovery zone, and is injected into the alumina cooling cyclones8311, along with ambient air. The byproduct heat from the alumina cooling cyclones is provided, through a baghouse and filter8317, as the recirculated gas for the input of the thermal storage unit. According to an alternative implementation, the TES system may only be used for providing the heat for the steam generator, so that the existing infrastructure of the alumina processing facility can be used without substantial modification. The example material activation system may have various benefits and advantages. For example, because the output of the waste heat recovery is recirculated as an input to the thermal energy storage, emission of heat through the stack is avoided. Thus, unnecessary heat emissions to the atmosphere can be avoided. Additionally, by using the incoming heat from the TES system, it is not necessary to use fossil fuel to provide the input heat. Further, because the combustion aspect of generating heat is removed, the free moisture in the input combustion stream is eliminated, which avoids the problems introduced by the presence of that moisture, particularly with respect to the calcination of clay, as explained above. The example implementation also has a benefit of more favorable thermodynamics and lower maximum temperatures. 3. Advantages Over Prior Systems The material activation system described herein may have various advantages and benefits over prior calcination implementations. For example, the material activation system may reduce or eliminate carbon dioxide emissions associated with cement manufacturing, by running partially or exclusively on renewable electricity using thermal energy storage arrays heated by electric power. Further, the modularity of the thermal energy storages and applicability in various parts of the cement production process allows for stepwise electrification, retrofitting and hybridization with fuel firing. Integration of thermal energy storage allows low cost, low carbon intensity, low capacity factor electricity to operate various processes in cement production or other industrial applications at high annual capacity factors that may be nearly equivalent to operation with fossil fuels. The material activation system described herein also addresses problems associated with moisture in clay. Clay is generally a very moist substance as it is often acquired in wet areas with relatively large amounts of both free moisture and crystal water in the structure of the mineral. The fuel consumption in the activation rises dramatically with the amount of free moisture present in the clay, due mostly to energy being wasted on a water phase change. This problem is further compounded by additional water vapor produced in combustion. The TES system, however, overcomes this problem as combustion is not the primary form of heat transfer. Not relying on combustion also allows the thermal storage system to have a higher degree of freedom in operating conditions since the air flow rate will not dramatically change the gas composition inside the reactor chamber. Another benefit to switching from combustion to electrically heated and stored energy is that, in clay activation, there exists an upper bound temperature at about 950° C., e.g., 950° C. where the clay mineral structure is destroyed to mullite and loses all of its desired qualities for use as an SCM. In combustion-driven processes, temperature profiles inside of reactors are much harder to control than with a fixed temperature gas heat source that is much easier to control and monitor. By decoupling the hot exhaust air from the rotary kiln from the preheater/precalciner inlet, one or more multiple potential benefits may be achieved. By decoupling the gas flow between the kiln and precalciner, gas flow and heating rates can be independently controlled to optimize each process. For example, in an air-through system, the amount of fuel that can be burned at the calciner can be limited due to excessive gas flow rates that can cool the flame temperature. Also, the heated exhaust gas from the kiln can be captured and used for alternative purposes, such as providing thermal energy to a power cycle to generate electricity. Further, the hot exhaust from the kiln may contain significant amounts of undesirable components such as alkali salts, which evaporate in the hotter sections of the kiln. These undesirable components may cause damage to equipment, cause clogging in the precalciner as it cools and reduce quality of the product as it recirculates. By decoupling the kiln and precalciner, the undesirable byproducts can be kept out of the precalciner and potentially captured. Additionally, heat required for the precalciner can be provided from a TES system powered by renewable energy or other sources, and optionally supplemented by a fuel fired source. As another benefit, the kiln and precalciner can be run on different gas makeups in some implementations. For example, the kiln may be heated by an oxyfuel energy source with added methane, resulting in a gas makeup consisting of predominantly CO2and H2O. This makeup avoids side reactions such as that of air nitrogen with oxygen, producing nitrogen oxides. Carbon dioxide and water can be utilized in processes described elsewhere in this disclosure. The precalciner can be run on air flowing through the thermal energy storage as it may be less expensive and may not have the problem of nitrogen gas reactions. The type of gas and combination of storage versus fuel energy source can be independently adjusted and potentially optimized in some embodiments. The use of carbon dioxide has various benefits and advantages. For example, carbon dioxide does not require an air separator and has thermal properties that are more conducive to heat transfer. Carbon dioxide also has a higher emissivity at high temperatures. Further, carbon dioxide is inert and does not combust, which as stated at the benefit involved. Because the carbon dioxide does not react with the resistive heaters, there is less oxidation or wear and tear on the resistive heaters of the thermal energy storages. The byproduct gas is recirculated as input fluid for the TES system, and carbon dioxide is not released into the atmosphere, which has an environmental benefit of reducing greenhouse gases. Prior approaches do not include an integrated process that uses hot gases generated from electric resistive heaters to supply all of the heat for a calcination process. Further, these approaches do not include an integrated process that uses a TES system that charges from electricity and discharges heated fluid directly into a flash-calcination process as the main mode of heat supply. Additionally, the material activation system may recirculate waste gases from the material heating system back to the TES system. This recirculated fluid may also have a desired composition to meet reaction and quality needs. B. Electrolysis The gas that is output from the TSU may be provided as the input for various industrial applications. One type of industrial application that uses and benefits from a continuous stream of heat at a constant temperature is electrolysis. The thermal energy storage system receiving electric power that can flow into a heat storage system (e.g., taking air in at 200° C. and delivering air in a range between 600° C. and 900° C. (such as 860° C.) when discharged for electrolysis). As explained below, art electrolysis systems can be improved by combination with the above described thermal energy storage system. 1. Problems to be Solved Solid oxide electrolyzers according to conventional designs receive an input of heated gas and water in the form of superheated steam. The gas is heated prior to input to the solid oxide electrolyzer by an electric resistive heater, a fuel heater, or the like. The use of an electric resistive heater or fuel heater for this purpose may have various problems and disadvantages. For example, fuel heaters may consume fossil fuels such as natural gas, which is expensive and causes pollution. Electric heaters powered directly by VRE sources cause problems with changing temperatures and limited operating periods. There are several types of fuel cells that take hydrogen or a mix of gases and make electric power, such as molten carbonate electrolyzer fuel cells, and solid oxide fuel cells. Such fuel cells use essentially the same as electrolyzers in reverse. However, solid oxide fuel cells have problems and disadvantages because the oxidation causes localized heating and issues with cell life. Solid oxide fuel cells require their inlet reactants and the fuel cell assembly to be maintained at particular temperatures. The operation of fuel cells delivers energy partly in the form of electrical energy and partly as heat. Further, solid oxide fuel cells require a recuperator (e.g., high temperature heat generator) to make use of a portion of the heat generated by the fuel cell. However, a substantial portion of the heat so generated is not used, which results in inefficiencies. 2. Reversible Solid Oxide Unit Solid oxide electrolyzers may include an electrolyzer producing hydrogen by using electrical energy to break apart the molecular bonds and drive apart the elemental ions that into separate outlet streams. Solid oxide electrolyzers have a porous cathode with a porous electrolyte that is catalytic when operated at temperatures at or above 830° C., and thermal energy is contributing to cracking those bonds. A solid oxide fuel cell is typically 40-50% efficient at taking fuel energy and making electric energy, with the rest of the energy being released as heat at around 850° C., e.g., 850° C. to 860° C., e.g., 860° C., in some cases, which are slightly higher temperatures than the optimal operational point for the solid oxide electrolyzer. A system may incorporate one or more solid oxide electrolyzers and one or more solid oxide fuel cells; a single solid oxide unit may operate reversibly as an electrolyzer or fuel cell. FIG.84provides an illustration4300of the solid oxide unit as a fuel cell4301and as an electrolyzer4303. The solid oxide fuel cell at4301receives as its input a gas such as hydrogen or carbon monoxide. The hydrogen or carbon monoxide is combined with oxygen enriched gas across a potential to output electrical energy4305and either water or carbon dioxide, depending on whether hydrogen or carbon monoxide, respectively, is the input. Similarly, as shown in the solid oxide electrolysis cell4303, water or carbon dioxide is provided as an input along with heat in the form of hot fluid from the thermal energy storage system, which obtains its energy from an electrical source such as the renewable wind source4307as illustrated. The output is hydrogen gas or carbon monoxide, depending on whether water or carbon dioxide was the input, as well as oxygen enriched gas as a byproduct. FIG.85illustrates the electrolysis mode4900of the example implementation. The thermal energy system4901receives electrical energy from a source, such as a VRE source4903, and/or from another source, either locally or via an electricity grid4905. The electricity source4903may also be coupled to other elements of the solid oxide electrolysis system, for example, to provide electrical potential for the electrolysis reaction. Fluid4902(e.g., hot air) is output from the thermal energy storage system4901and provided to the solid oxide electrolysis cell4907. Fluid4902may be at a temperature between 800° C. and 900° C. (such as 850° C.). Solid oxide electrolysis cell4907may also receive steam4904, which may be at a temperature near fluid4902(for example, 830° C.). The solid oxide electrolysis cell4907may receive electricity from the electricity source4903and generate as its output hydrogen as the product gas4908along with oxygen enriched hot fluid4923as a byproduct. The product gas4908(e.g., hydrogen) is cooled via a heat exchanger. The heat exchanger may reject heat to the environment or, more efficiently, may deliver heat to a thermal load, such as a once-through steam generator (OTSG)4911, as its input. The product gas flows through the heat exchangers of the OTSG4911, which is supplied by cold water from a source4913. As the product gas4908is cooled by the heat exchanger/OTSG4911, much of its carried water is condensed, becoming condensed product gas4912. The condensed product gas4912is primarily provided to a hydrogen processing unit4915, which in turn provides the hydrogen gas in a storage ready form to storage4917. A portion of the condensed product gas is recirculated at4919to be mixed with the input steam4904. In one implementation, steam4904, or a portion of the steam, may be the output of the OTSG4911, as shown at4921. In a manner similar to that explained above for OTSG4911, another OTSG4931may be provided, having water supplied from a source4933. As previously discussed, the OTSG4931may be any heat exchanger heating a fluid, including a recirculating boiler with or without superheat, or a unit that heats circulating air, CO2, oil, water, or salt. The OTSG4931receives the oxygen enriched hot fluid, and outputs the cooled fluid at4937. In some implementations, the OTSG4931may receive another stream of hot fluid from the thermal energy system4901so as to adjust the temperature or heat flow of the combined stream to a more useful condition. The cooled, oxygen-enriched fluid4937may be mixed with ambient or preheated air at4935, to adjust the composition of oxygen to a desired level. The adjusted fluid4939may be provided as an input gas to the thermal energy storage system4901. FIG.86illustrates the fuel cell mode5000according to an example implementation. The thermal energy storage system5001provides air or oxygen as shown at5002, such as explained above with respect to the electrolysis mode. Separately, a supply of hydrogen5003is provided. The hydrogen is heated up via the single pass heat exchanger5005by the hot fluid from the thermal energy storage system. Optionally, a small amount of steam may be mixed in with the hydrogen gas to avoid degradation of the solid oxide unit. The fluid from the thermal energy storage system may be provided at a temperature that is lower than that of the electrolysis mode, such as 650° C. or in a range between 600° C. and 700° C. In the fuel-cell mode of operation, the air5030may provide a cooling effect in solid oxide fuel cell5007. The air5002from the thermal energy storage system5001and the heated hydrogen from the hydrogen storage5003are input as shown by5004and5030respectively to the solid oxide fuel cell5007. As its output, the solid oxide fuel cell5007generates direct current electricity at5006. In one implementation, the direct current electricity is provided to an inverter to convert to an alternating current power output, which can be provided to any use5009(which may, e.g., be a power grid). Additional outputs of the solid oxide fuel cell5007include water and hydrogen as a product fluid at5011, and heated, oxygen-depleted air at5021. The product fluid at5011is provided to heat exchanger5013, which cools the product fluid by heating another fluid which may be water, air, or another fluid received as shown at fluid source5015. The output includes export steam, which may be provided as an input to an industrial application that requires steam, such as a steam turbine as explained above. Additionally, residual hydrogen may be recirculated, by way of a heat exchanger5005, to the solid oxide fuel cell5007, as shown at5027. The oxygen-depleted fluid5021, optionally supplemented with other hot fluid from the storage5031, is provided as the heating gas for the heat exchanger5013, and subsequently provided as the input fluid for the thermal energy storage system5001, as shown at5025. It is noted that the solid oxide fuel cell5007generates electricity and heat. Thus, the input fluid from the thermal energy storage system5001, which is at about 650° C., e.g., 650° C. in this example, is provided as cooling air for the solid oxide fuel cell5007. FIG.87illustrates an example system4100used to power the production of hydrogen and/or hydrocarbon fuels by delivering both heat and power to drive a high-temperature solid-oxide electrolyzer. Solid-oxide electrolyzers can reduce the electrical energy input needed per unit of hydrogen by harnessing thermal energy to drive the breaking of chemical bonds. Relatively higher total efficiency may be achieved by directing a portion4101of the high-temperature stored heat from thermal energy storage system4105as high-temperature heat to an electrolyzer4102which is also fully or partially powered by electricity4103generated by a thermal generation process4104. Thermal generation process4104may include, for example, a Rankine cycle or supercritical CO2cycle. In some implementations, the electrolyzer4102may co-electrolyze water and CO2(separate electrolyzers may also be used to electrolyze water and CO2) with all or a portion of the resulting syngas directed to a methanation or Fischer-Tropsch type conversion unit4109. Unit4109may make a synthetic gaseous or liquid hydrocarbon fuel, shown at4106. Additionally, a once-through steam generator (OTSG)4107may be provided as a condenser that cools the output fluid of the solid oxide electrolysis unit4102and provides the steam as an input to the solid oxide electrolysis unit4102. The byproduct hot fluid is recirculated back to the thermal energy storage system4105as an input fluid. As explained above, the electrolyzer is reversible as a fuel cell. Thus, when the renewable input power such as the photovoltaic array is unavailable or when electricity is needed by the grid, hydrogen can be fed to the fuel cell and water, electricity, and heat can be output from the system. The heat is at a high enough temperature that the heat can be used to produce steam or utilized in another industrial process. Accordingly, less heat is extracted out of the heat storage unit as it is replaced with what would otherwise be waste heat coming from the fuel cell. Alternatively, the gas flow can be reversed, and heat can be put convectively back into heat storage. Thus, when the system is performing co-generation and running heat, the waste heat from the fuel cell can be used to either displace energy that would otherwise have been discharged from heat storage or be returned to heat storage. The efficiency in the electrolyzer dramatically improves when using hot fluid from the thermal energy storage system. Further, if none of the outlet steam is being used, the captured heat can be repurposed. For example, hydrogen is produced in one implementation, with a fraction being sold and another fraction being used for power generation. The waste heat from power generation may be recaptured and used to reduce the electricity used for electrolysis during the next period, such as the next day. Further, in some example implementations, one or both of the convective waste heat from the fuel cell and input electric heat may be used to charge the thermal storage unit. In one implementation, the system may incorporate 1) a solar array or other intermittent electricity source; 2) a combination electrolyzer/fuel cell-heat storage unit; and 3) a lithium-ion battery and an electric vehicle charging station and a hydrogen filling station. This system can be used to store energy as hydrogen that may participate in providing the off-hours electricity for EV charging but is also available for dispensing to vehicles as hydrogen charging. FIG.88illustrates a reversible solid oxide electrolysis system4800according to an example implementation. The thermal energy storage system4801provides hot fluid (e.g., hot gas)4809at its output. As shown in this example, the composition of the fluid is 53% nitrogen gas and 47% oxygen gas, at a temperature of 855° C. and a flow rate of 1620 kg per hour. However, the composition of the oxygen or nitrogen can be adjusted based on the operating parameters of the solid oxide cell4803. For instance, the gas may have an oxygen volume percentage between 25% and 60%. Additionally, the temperature or flow rate may be varied. For example, the temperature may be between 800° C. and 900° C. or the flow rate may be between 1500 kg/hr. and 2000 kg/hr. The hot fluid4809is provided to a solid oxide unit4803. In this case, the solid oxide unit is a two-way reversible unit. For example, solid oxide unit4803can operate in electrolysis mode, which produces an endothermic reaction, or in fuel cell mode, which produces an exothermic reaction. The solid oxide unit4803is currently described in electrolysis mode. The solid oxide cell4803in electrolysis mode receives the hot fluid4809from the thermal energy storage system4801. Because the solid oxide unit4803in electrolysis mode operates such that the internal resistance does not generate enough heat to overcome the endothermic reaction, the solid oxide unit4803is operating in thermal neutral voltage mode. Although it is not shown, each of the cells receives an electrical input at 1.28 V. Other voltages may also be possible such as a voltage in a range between 1 volt and 3 volts. In various embodiments, hot fluid4809is passed through the solid oxide cells as a sweep fluid (e.g., sweep gas). In addition to the hot fluid4809(e.g., sweep fluid) provided by the thermal energy storage unit, a reaction fluid (e.g., steam mixed with hydrogen)4811is also provided as an input to solid oxide unit4803. In this example, the reaction fluid4811is provided having 96% water and 4% hydrogen gas, at a superheated temperature of 807° C. and at a flow rate of 814 kg per hour. The percentage of water, temperature, or flow rate of reaction fluid4811may be varied. In various implementations, the temperature of reaction fluid4811is at a temperature below hot fluid4809but at a temperature above 800° C. In some implementations, the flow rate of reaction fluid4811is balanced with the flow rate of hot fluid4809to provide desired reaction results in solid oxide unit4803. The reaction fluid4811is provided to the solid oxide unit4803. As a result of the reaction in the solid oxide cell, the water molecule is split and the resulting ions form oxygen gas and hydrogen gas. At the same time, the sweep gas (e.g., hot fluid4809) pulls the oxygen off of the air electrode as the water comes in on the cathode and strips the oxides off of the water. As outputs, the solid oxide cell in electrolysis mode produces product fluid4813as well as oxygen enriched fluid4815(e.g., oxygen enriched air). In certain implementations, the temperature of the product gas is near a temperature of the oxygen enriched fluid. Both fluids may be at a temperature between a temperature of the reaction fluid and a temperature of the hot fluid4809. In the illustrated embodiment, the product fluid4813is 76% hydrogen and 24% water by volume, which corresponds to 26% hydrogen and 74% water by weight. The temperature of the product fluid4813is 830° C. and it is provided at a flow rate of 274 kg per hour. The enriched fluid4815is a composition of 60% oxygen and 40% nitrogen by volume, at a temperature of 830° C., and at a flow rate of 2159 kg per hour. The composition, temperature, and flow rate of the product fluid4813and enriched fluid4815may vary based on the operating conditions of the system. For product fluid4813, a thermal load such as an OTSG4805including heat condensers is provided. OTSG4805uses water to cool and condense the hydrogen gas. More specifically, the product fluid4813enters the OTSG4805, where it is exposed to water that is run through pipes. The source of the water for the OTSG4805is a water reservoir4817, where the water is provided at a relatively cool temperature such as 25° C. As the water passes through the various condensers, the water becomes more and more heated from the exit to the entrance of the condenser. More specifically, the water reservoir4817provides the clean water and condensate to a first stage of the heat exchanger, where the product fluid is at its coolest point of the three heat exchangers. The water then flows to a second heat exchanger that is upstream of the first heat exchanger, and the product fluid is warmer than at the first heat exchanger. At the third heat exchanger, the product fluid4813is incoming, and is at its hottest point. While the heat exchangers of the condenser are shown as having three stages, the heat exchanger may be varied to have more or fewer stages as a matter of design choice. As a result of the heat exchange, the condenser operates as the OTSG4805, because as the water absorbs the heat from the hot hydrogen product fluid4813, the water is converted to steam, and the steam is provided to the input of the solid oxide unit at a temperature of around 830° C., e.g., 830° C. The steam is then provided as4837and input to the solid oxide unit at4811. Because the solid oxide unit4803is sensitive to contamination, the source4817of the water for the condenser is purified water. Optionally, the purified water may be combined with the condensate output1819of the condenser. As the hydrogen passes through the condenser, water is removed from the hydrogen gas as condensate due to the hot hydrogen gas passing over the cool pipes of the condenser. The output4821of the condenser is dry product fluid, namely dry hydrogen gas. The hydrogen gas is provided to an industrial application at4823, as explained above. At4825, some of the hydrogen gas (e.g., knock-off hydrogen gas having some water mixed in) is fed back into the input of the solid oxide unit4803in combination with the steam that is formed at the output of the condenser as explained above. The hydrogen gas is combined with steam at the input of the solid oxide because 100% steam cannot be input to the solid oxide unit due to degradation issues. Optionally, the gas that is output from the thermal energy storage system may be provided at a temperature based on a parameter of the solid oxide electrolyzer, such as the operating temperature. Because the thermal energy storage system provides the constant flow of heated fluid4809at the temperature required for the solid oxide cell in electrolysis mode, there is no need for electric resistive heaters as in prior systems. Thus, the solid oxide cell4803may be provided and used without a heater. However, electric resistive heaters (or other heaters) may be optionally added, to provide temperature adjustments or calibration at the entrance of the solid oxide unit. As the oxygen enriched fluid4815is input to the OTSG4807, the water from the water reservoir4827interacts with the enriched fluid, in a manner similar to that described above for the product fluid. Thus, heat is transferred to the water that passes through the heat exchangers. Such water is output as steam at4839and provided to the input of the solid oxide unit as part of reaction fluid4811along with the steam from the product fluid condenser and the recirculated hydrogen gas. The enriched fluid may also be vented at4831. The enriched fluid is output at4829. The enriched fluid is output to the atmosphere as air at standard atmospheric composition at4833. Additionally, oxygen enriched fluid may be recycled at4835after blending with atmospheric air, such that the composition of the fluid is 53% nitrogen and 47% oxygen, for example. This fluid is provided as an input to the thermal energy storage system4801, where it is heated in the thermal storage arrays and provided as an output to the solid oxide unit as hot fluid at4809, as explained above. Further, the blending of the oxygen enriched fluid with atmospheric air also has a benefit for the thermal energy storage system4801, in that problems and disadvantages associated with having oxygen enriched fluid in the thermal energy storage system, such as potential oxidation of components, are avoided. Additionally, the temperature of the heat that is generated by the thermal energy storage system may be provided to the solid oxide unit at a temperature that is thermally neutral. In other words, because the hot fluid4809is provided at an elevated temperature, such as 855° C., the system is in an isothermic condition, and the system does not have any net heat demands. In other words, the chemical reactions in the solid oxide unit4803will cool the system, whereas the only resistance within the thermal energy storage system is from the heating elements that generate heat from electrical energy. The result is that there is no net temperature change and a substantially lower energy cost. Accordingly, there is cost savings in that it is not necessary to add additional resistive heaters or fuel meters to the solid oxide unit to heat the incoming air. However, it should be noted that the electrolyzer need not be operated at the isothermal temperature and may instead use heat that is generated at a higher or lower temperature. As noted above, the solid oxide unit is reversible, such that it can be used as an electrolyzer, as explained above, or as a fuel cell. The fuel cell operation may include, using the structures as explained above, with the thermal energy storage unit providing oxygenated enriched fluid that is combined with compressed hydrogen to produce direct current electricity and water, as described herein. Additionally, in some implementations, when the solid oxide unit is not operating the hot fluid4809generated by the thermal energy storage system may continue to be provided through the solid oxide unit. The benefit of flowing such hot fluid through the solid oxide unit when the system is not in use is that the ramping down during the cooling process and the ramping up during the heating process before and after active operation (e.g., thermal cycling), respectively, is avoided. Additionally, the wear and tear on the unit during those processes is also avoided and, in addition, the time and cost of cooling and heating of the various components is reduced (such as the ceramic inside the solid oxide unit). Further, it is possible to switch loads, between the different modes of operation (such as electrolyzer and fuel cell), without shutting down and warming up the unit. In some implementations, the solid oxide unit may continue to be heated by hot fluid4809at temperatures around those utilized during fuel cell operations. The composition of the fluid flowing within the thermal energy storage unit may be adjusted by the extraction of oxygen enriched fluid4829and/or the introduction of ambient fresh air. The oxygen enriched fluid extracted may be used for another purpose, including the purification and supply of oxygen for a commercial purpose. In addition, hydrogen and oxygen production may be coupled with other processes such as hydrogenation of CO2or CO to make liquid fuels or remediation of contaminated groundwater contamination using oxygen. Excess heat, such as from a Fischer-Tropsch process, could be used to convectively charge or pre-heat fluid for the thermal storage unit. Other electrolysis processes benefitting from renewable electricity or thermal energy can also be coupled to the storage system. As an example, a direct co-electrolysis of CO2in combination with the water-gas shift reaction and steam to produce syngas, which can further be processed in a Fischer-Tropsch reactor for conversion to hydrocarbons, is optimal at a temperature serviceable from a renewable energy storage unit, as described above, and powered using the DC architecture described previously. Nickel-based electrodes may also be utilized to obtain methanation of carbon monoxide (e.g., Sabatier reaction), with the ratios of various component products being controlled by temperature, pressure, and concentration of components in equilibrium. It may be particularly valuable to locate a facility that combines energy storage, Fischer-Tropsch, Sabatier, and co-electrolysis processes at a bio-refinery (such as an ethanol refinery (that has a large supply of biogenic CO2available from the fermenter) or another processing facility such as a renewable diesel refinery (which has CO2streams arising from process units and has fuel production equipment that can purify the products arising from the Fischer-Tropsch reaction). The system may also be used in industrial loads such as renewable diesel refineries, petroleum refineries, or oil fields where there is very high value for hydrogen that is participating in the chemical process. There is also very high value for 24-hour, zero carbon electric power. For instance, instead of producing hydrogen and power at low efficiency, this set of systems allows conversion of essentially every kilowatt hour that comes into the system either leaving as a kilowatt hour of enthalpy and hydrogen or a kilowatt hour of heat or a kilowatt hour of electricity with very high efficiency (for example, 96 percent total system efficiency). In various implementations, fluids that are flowing in and out of the heat storage unit can be directly coupled with the fluids that are flowing across one side of the electrolyzer (e.g., the oxygen side). As such integration of a directly heated contact and a directly cooled contact may assist with integration of the fuel cell. In addition to being connected to the solid oxide electrolysis cell, the thermal energy storage system having electric power that can flow into a heat storage system taking fluid in at 200° C. and delivering fluid at a temperature of 800° C.-1600° C. when discharged as explained above, such as the system disclosed above, can perform district heating, driving of turbines, cogeneration, or other industrial uses. For example, in the case of the solid oxide fuel cell mode, the heat generated in the process of making electricity from a hydrogen input may be used as an industrial output for a steam generator in one implementation. Further, the excess electricity generated by the steam generator may be combined with the electricity provided from the source, such as the renewable source, as the electrical input for the thermal heaters of the thermal energy storage system according to the example implementations. 3. Advantages Over Prior Systems The solid oxide unit of the example implementations may have various benefits and advantages over prior designs. For example, the solid oxide unit described herein receives stored heat from the thermal energy storage system as its input, instead of requiring an external heater, such as an electrical resistive heater or a fuel fired heater. Thus, the cost of operation may be reduced and the amount of pollution may also be reduced. Further, while art approaches may burn the oxygen byproduct at the output of the solid oxide unit to generate heat for the heater that the input of the solid oxide unit, the example implementations do not require heat to be generated at the input of the solid oxide unit. Thus, the byproduct air is provided to the heat exchanger, without burning off the oxygen. The enhanced concentration of oxygen in the flow may contribute to reductions in the cost of secondary oxygen separation. Such solid oxide electrolyzer integration with thermal energy storage has benefits including significantly enhanced efficiency in the conversion of electrical energy to energy and hydrogen and enabling such high efficiency electrolyzers to be combined and used effectively with variable supplies of renewable electricity. Accordingly, charging may be intermittent while temperature is held constant without continuous use of electrical power. Also, a portion of the energy in the electrolytic process in this manner is supplied by stored heat. It is beneficial to do this because the time at which electricity may be captured and stored may be separated from the time at which electricity is captured and used for electrolysis. When electric power is available, the electric power can be used to heat charge the storage system and also drive electrolysis to convert water to hydrogen. Existing electrolyzers cost around $500-600/kW, whereas heat storage systems may be significantly less expensive. Heat storage may be less expensive on a per kilowatt basis than electrolyzer stacks and it may therefore be less costly to pull power in at a very high rate during periods of lower-cost power availability and apportion the power between the heat storage and the electrolyzer. The electrolyzer can be made to run longer and the peak load or the peak power can be dropped quickly into heat storage. Thus, there is a matching of electrolyzer capacity factor and cost against the availability of variable renewable electricity C. Thermoelectric Power Generation 1. Problems to be Solved Gasification is the thermal conversion of organic matter by partial oxidation into gaseous product, consisting primarily of H2, carbon monoxide (CO), and may also include methane, water, CO2and other products. Biomass (e.g. wood pellets), carbon rich waste (e.g. paper, cardboard) and even plastic waste can be gasified to produce hydrogen rich syngas at high yields with high temperature steam, with optimum yields attained at >1000° C. The rate of formation of combustible gases are increased by increasing the temperature of the reaction, leading to a more complete conversion of the fuel. The yield of hydrogen, for example, increases with the rise of reaction temperature. Turning waste carbon sources into a useable alternative energy or feedstock stream to fossil fuels is a potentially highly impactful method for reducing carbon emissions and valorizing otherwise unused carbon sources. 2. Thermoelectric Power Generation Indirect gasification uses a Dual Fluidized Bed (DFB) system consisting of two intercoupled fluidized bed reactors—one combustor and one gasifier—between which a considerable amount of bed material is circulated. This circulating bed material acts as a heat carrier from the combustor to the gasifier, thus satisfying the net energy demand in the gasifier originated by the fact that it is fluidized solely with steam, i.e. with no air/oxygen present, in contrast to the classical approach in gasification technology also called direct gasification. The absence of nitrogen and combustion in the gasifying chamber implies the generation of a raw gas with much higher heating value than that in direct gasification. The char which is not converted in the gasifying chamber follows the circulating bed material into the combustor, which is fluidized with air, where it is combusted and releases heat which is captured by the circulating bed material and thereby transported into the gasifier in order to close the heat balance of the system. Referring toFIG.6, in some example implementations, the thermal energy storage structure503can be integrated directly with a steam power plant to provide an integrated cogeneration system500for a continuous supply of hot air, steam and/or electrical power for various industrial applications. Thermal storage structure503may be operatively coupled to electrical energy sources501to receive electrical energy and convert and store the electrical energy in the form of thermal energy. In some implementations, at least one of the electrical energy sources501may comprise an input energy source having intermittent availability. However, electrical energy sources501may also include input energy sources having on-demand availability, and combinations of intermittent and on-demand sources are also possible and contemplated. The system503can be operatively coupled to a heat recovery steam generator (HRSG)509which is configured to receive heated air from the system503for converting the water flowing through conduits507of the HRSG509into steam for the steam turbine515. In an alternative implementation, HRSG509is a once-through steam generator in which the water used to generate steam is not recirculated. However, implementations in which the water used to generate steam is partially or fully circulated as shown inFIG.6are also possible and contemplated. A control unit can control the flow of the heated air (and more generally, a fluid) into the HRSG509, based on load demand, cost per KWH of available energy source, and thermal energy stored in the system. The steam turbine515can be operatively coupled to a steam generator509, which can be configured to generate a continuous supply of electrical energy. Further, the steam turbine515can also release a continuous flow of relatively lower-pressure521steam as output to supply an industrial process. Accordingly, implementations are possible and contemplated in which steam is received by the turbine at a first pressure and is output therefrom at a second, lower pressure, with lower pressure steam being provided to the industrial process. Examples of such industrial process that may utilize the lower pressure output steam include (but are not limited to) production of liquid transportation fuels, including petroleum fuels, biofuel production, production of diesel fuels, production of ethanol, grain drying, and so on. The production of ethanol as a fuel from starch and cellulose involves aqueous processes including hydrolysis, fermentation and distillation. Ethanol plants have substantial electrical energy demand for process pumps and other equipment, and significant demands for heat to drive hydrolysis, cooking, distillation, dehydrating, and drying the biomass and alcohol streams. It is well known to use conventional electric power and fuel-fired boilers, or fuel-fired cogeneration of steam and power, to operate the fuel production process. Such energy inputs are a significant source of CO2emissions, in some cases 25% or more of total CO2associated with total agriculture, fuel production, and transportation of finished fuel. Accordingly, the use of renewable energy to drive such production processes is of value. Some ethanol plants are located in locations where excellent solar resources are available. Others are located in locations where excellent wind resources are available. The use of electrothermal energy storage may provide local benefits in such locations to grid operators, including switchable electricity loads to stabilize the grid; and intermittently available grid electricity (e.g. during low-price periods) may provide a low-cost continuous source of energy delivered from the electrothermal storage unit. The use of renewable energy (wind or solar power) as the source of energy charging the electrothermal storage may deliver important reductions in the total. CO2emissions involved in producing the fuel, as up to 100% of the driving electricity and driving steam required for plant operations may come from cogeneration of heat and power by a steam turbine powered by steam generated by an electrothermal storage unit. Such emissions reductions are both valuable to the climate and commercially valuable under programs which create financial value for renewable and low-carbon fuels. The electrothermal energy storage unit having air as a heat transfer fluid may provide other important benefits to an ethanol production facility, notably in the supply of heated dry air to process elements including spent grain drying. One useful combination of heated air output and steam output from a single unit is achieved by directing the outlet stream from the HRSG to the grain dryer. In this manner, a given amount of energy storage material (e.g. brick) may be cycled through a wider change in temperature, enabling the storage of extra energy in a given mass of storage material. There may be periods where the energy storage material temperature is below the temperature required for making steam, but the discharge of heated air for drying or other operations continues. In some implementations thermal storage structure503may be directly integrated to industrial processing systems in order to directly deliver heat to a process without generation of steam or electricity. For example, thermal storage structure503may be integrated into industrial systems for manufacturing lime, concrete, petrochemical processing, or any other process that requires the delivery of high temperature air or heat to drive a chemical process. Through integration of thermal storage structure503charged by VRE, the fossil fuel requirements of such industrial process may be significantly reduced or possibly eliminated. The control unit can determine how much steam is to flow through a condenser519versus steam output521, varying both total electrical generation and steam production as needed. As a result, the integrated cogeneration system500can cogenerate steam and electrical power for one or more industrial applications. If implemented with an OTSG as shown inFIG.4instead of the recirculating HRSG shown inFIG.6, the overall integrated cogeneration system500can be used as thermal storage once-through steam generator (TSOTG) which can be used in oil fields and industries to deliver wet saturated steam or superheated dry steam at a specific flow rate and steam quality under automated control. High temperature delivered by the bricks and heating elements of the system503can power the integrated heat recovery steam generator (HRSG)509. A closed air recirculation loop can minimize heat losses and maintain overall steam generation efficiency above 98%. The HRSG509can include a positive displacement (PD) pump511under variable frequency drive (VFD) control to deliver water to the HRSG509. Automatic control of steam flow rate and steam quality (including feed-forward and feed-back quality control) can be provided by the TSOTG500. In an exemplary example implementation, a built-in Local Operator Interface (LOI) panel operatively coupled to system500and the control unit can provide unit supervision and control. Further, thermal storage structure503can be connected to a supervisory control and data acquisition system (SCADA)) associated with the steam power plant (or other load system). In one implementation, a second electrical power source is electrically connected to the steam generator pumps, blowers, instruments, and control unit. In some implementations, system500may be designed to operate using feedwater with substantially dissolved solids; accordingly, a recirculating boiler configuration is impractical. Instead, a once-through steam generation process can be used to deliver wet steam without the buildup of mineral contaminants within the boiler. A serpentine arrangement of conduits507in an alternative once-through configuration of the HRSG509can be exposed to high-temperature air generated by the thermal storage structure503, in which preheating and evaporation of the feedwater can take place consecutively. Water can be forced through the conduits of HRSG509by a boiler feedwater pump, entering the HRSG509at the “cold” end. The water can change phase along the circuit and may exit as wet steam at the “hot” end. In one implementation, steam quality is calculated based on the temperature of air provided by the thermal storage structure503, and feedwater temperatures and flow rates, and is measured based on velocity acceleration at the HRSG outlet. Embodiments implementing a separator to separate steam from water vapor and determine the steam quality based on their relative proportions are also possible and contemplated. In the case of an OTSG implementation, airflow (or other fluid flow) can be arranged such that the hottest air is nearest to the steam outlet at the second end of the conduit. An OTSG conduit can be mounted transversely to the airflow path and arranged in a sequence to provide highly efficient heat transfer and steam generation while achieving a low cost of materials. As a result, other than thermal losses from energy storage, steam generation efficiency can reach above 98%. The prevention of scale formation within the tubing is an important design consideration in the selection of steam quality and tubing design. As water flows through the serpentine conduit, the water first rises in temperature according to the saturation temperature corresponding to the pressure, then begins evaporating (boiling) as flow continues through heated conduits. As boiling occurs, volume expansion causes acceleration of the rate of flow, and the concentration of dissolved solids increases proportionally with the fraction of liquid phase remaining. Maintaining concentrations below precipitation concentration limits is an important consideration to prevent scale formation. Within a bulk flow whose average mineral precipitation, localized nucleate and film boiling can cause increased local mineral concentrations at the conduit walls. To mitigate the potential for scale formation arising from such localized increases in mineral concentration, conduits which carry water being heated may be rearranged such that the highest temperature heating air flows across conduits which carry water at a lower steam quality, and that heating air at a lower temperature flows across the conduits which carry the highest steam quality flow. Returning toFIG.6, various implementations are contemplated in which a fluid movement device moves fluid across a thermal storage medium, to heat the fluid, and subsequently to an HRSG such as HRSG509for use in the generation of steam. In one implementation, the fluid is air. Accordingly, air circulation through the HRSG509can be forced by a variable-speed blower, which serves as the fluid movement device in such an embodiment. Air temperature can be adjusted by recirculation/mixing, to provide inlet air temperature that does not vary with the state of charge of the bricks or other mechanisms used to implement a thermal storage unit. The HRSG509can be fluidically coupled to a steam turbine generator515, which upon receiving the steam from the HRSG509, causes the production of electrical energy using generator517. Further, the steam gas turbine515in various embodiments releases low-pressure steam that is condensed to a liquid by a condenser519, and then de-aerated using a deaerator513, and again delivered to the HRSG509. An exemplary configuration specification of one implementation of a cogeneration system using an OTSG for steam generation is provided below.Parameter ValueNominal Steam Delivery 5,000 barrels per daySteam Quality (nominal) 80%; (60%-96%)Max Charging Rate 70 MWEnergy Storage 350 MWhEnergy Output from Storage 15 hours at max rateStorage Loss Rate 1% per dayOutlet Pressure 900 to 2200 psig (per spec)Inlet Pressure 50 psig (PD pump) or per specRunning Power Per outlet pressure, up to 450 kWDimensions 35×60 ft (11×18 m)Installation Outdoor Referring toFIG.89, in some example implementations, an integrated cogeneration system500as shown inFIG.6is coupled to a fuel-powered generator to provide a thermal storage integrated combined cycle plant550for efficient and reliable operation of a steam power plant. A combined cycle power plant may include a gas powerplant including a compressor502that mixes air into a fuel stream. The fuel and air mixture are then burnt in an expansion turbine516to generate pressurized exhaust, which is provided to a generator518to produce electrical energy. Further, the combined cycle plant may transfer the exhaust gas to a heat recovery steam generator (HRSG)509. The HRSG509may include a positive displacement (PD) pump511under variable frequency drive (VFD) control to deliver water to the HRSG509. When operating as part of a fuel-powered cycle, HRSG509uses the thermal energy of the exhaust gas from turbine516to convert the water into steam. Output of the HRSG509can be operatively coupled to a steam turbine generator515, which upon receiving the steam from the HRSG509, produces electrical energy using generator517. Further, the steam gas turbine515releases low-pressure steam that is condensed to a liquid by a condenser519, and then de-aerated using a deaerator513, and again delivered to the HRSG509. For example, as shown in the expanded view, the steam turbine generator515receives high pressure steam from the HRSG509. At a first turbine515A that is powered by the high pressure steam, intermediate pressure steam is output to the deaerator513, which may remove the oxygen from the steam, and provide as its output liquid fluid to the input of the HRSG509via PD pump511. An output of the first turbine515A may be low pressure steam, which is provided to an industrial process. A second turbine515B that is powered by the remaining pressurized steam also generates electricity, and provides low pressure steam as its output to a condenser. An output of the condenser may be warm air, which may be used for an industrial process, such as grain drying or the like. The thermal storage integrated combined cycle plant550can include the thermal energy storage structure503being fluidically coupled to the HRSG509of the combined cycle power plant. In one implementation, the heated air (at a predefined temperature) for the HRSG is provided by the thermal storage structure503alone or in combination with the exhaust emitted by the gas turbine516. A control unit can control the flow of any combination of the heated air (from thermal storage structure503) and exhaust gas by the gas turbine516into the HRSG509, based on, for example, factors including load demand, availability and cost per KWH of available energy sources, cost per KWH for the operation of the combined cycle power plant, and thermal energy stored in the thermal storage structure503. In other example implementations, thermal storage structure503and a coal power plant may be integrated with a steam power plant through the HRSG509to provide another example implementation of a thermal storage integrated combined cycle plant for efficient and reliable operation of a steam power plant. The heated air being provided by thermal storage structure503, alone or in combination with the exhaust emitted by the coal power plant can be supplied to the HRSG509for converting the water into steam for the steam turbine. A control unit may control the flow of any combination of the heated air (from the thermal storage structure) and exhaust gas by the coal power plant into the HRSG, based on, for example, factors including load demand, availability and cost per KWH of an available energy source, cost per KWH for the operation of the coal power plant, and thermal energy stored in the thermal storage structure. Referring toFIG.90, an integrated cogeneration system capable of delivering high-pressure steam as well as electric power may be configured as shown in one implementation. A thermal storage structure400as described inFIG.4may be configured with an integrated HRSG that delivers high-pressure, optionally superheated steam that flows through a steam turbine602that drives an electric generator604, which may be electrically coupled to local electrical loads or an electrical grid606to maintain and/or provide a continuous supply of electrical power at a load. All or a portion of the exhaust steam from the steam turbine may flow through a heat exchanger610which cools the steam into condensate which is returned for reheating by pump611. The heat exchanger610transfers the heat into a flow of water612which is directed through another HRSG613in thermal storage structure608, which provides steam for an industrial process. The heat transferred by heat exchanger610increases the steam production by HRSG613by preheating the inlet water. This accomplishes high-efficiency cogeneration of electric power and process steam, even when the required steam is at high temperatures and pressures, by capturing low-temperature thermal energy from the waste steam of turbine602into the feedwater of HRSG613. Referring toFIG.87as discussed above, in some implementations a thermal energy storage system may be used to power the production of hydrogen and/or hydrocarbon fuels by delivering both heat and power to drive a high-temperature solid-oxide electrolyzer. Solid-oxide electrolyzers can reduce the electrical energy input needed per unit of hydrogen by harnessing thermal energy to drive the breaking of chemical bonds. Relatively higher total efficiency may be achieved by directing a portion4101of the high-temperature stored heat from VRE as high-temperature heat to an electrolyzer4102which is also fully or partially powered by electricity4103generated by a thermal generation process4104, such as a Rankine cycle or supercritical CO2cycle. In some implementations, electrolyzer4102may co-electrolyze water and CO2, or separate electrolyzers may electrolyze water and CO2, with all or a portion of the resulting syngas directed to a methanation or Fischer-Tropsch type conversion unit4105so as to make a synthetic gaseous or liquid hydrocarbon fuel. In one implementation, stored VRE and an HRSG are coupled to an industrial process facility in such a manner as to eliminate gas combustion in auxiliary, emergency, or backup boilers. Referring toFIG.91, an industrial process plant such as a refinery, petrochemical plant, or other process plant91600may have one or more steam distribution networks91601that provide steam to process units such as pumps91604, blowers91605, process reactors91606, turbines91607, or other uses. In one implementation, the continuous operation of the steam network is required for the safe operation of the plant, including during startup and shutdown operations. Some industrial process units91602, principally those with exothermic reactions, may generate all or a portion of the steam91603in the network during normal operation. In some implementations, however, for the safe and effective operation of the plant other sources of steam must be instantly available in the event of the shutdown of one such unit91602. In some prior implementations gas-fired or oil-fired boilers91611have been used. In some implementations such equipment must be maintained at operating temperature continuously in order to be able to immediately increase its firing rate to provide the steam necessary in such a shutdown event. Such units may employ a conventional recirculating design with a steam drum91613which is open to the main steam network, and the heat necessary to keep the drum warm may be provided by excess steam produced by the process units91602. However, the firebox or burner portion of the boiler must also be kept warm in some implementations, and this is commonly done by operating the burner91612continuously at a low firing rate. This is a source of continuous CO2and other pollutants. In the depicted implementation of a thermal energy storage system, the thermal storage unit91608has an HRSG with recirculating drum boiler process91609, where the drum is again open to the steam header91601and the HRSG section is kept warm by excess steam. The thermal storage unit may maintain its temperature via its insulation, with low energy losses. The storage unit may be charged by a directly-connected VRE source, or may be rapidly or slowly charged from an electricity grid or a local power generation source, in such a manner as to minimize energy cost. The storage unit is configured to instantly (within seconds) begin high-rate steam production from storage, and operate until storage capacity is exhausted. In this implementation the fuel-fired boiler91611may be left in a “cold storage” configuration, burning no fuel, until a shutdown requires its operation. The operating time of the thermal storage unit provides an extended time period to properly start and warm up the fuel-fired boiler before placing it into service for outages that extend beyond the discharge period of the storage unit. Other Energy Usage Applications FIG.92is a schematic illustration10000that shows the availability of electricity from a solid oxide generation facility on a typical day. The illustration shows potential uses for available electric power. In one implementation, use 1 is the local consumption of relatively high-price electricity used at the industrial facility itself. As power production from a solar facility begins in early morning, the electricity is supplied to that highest value use first as the available solar electricity production rises. More specifically, the time of operation or charging may be controlled in such a manner as to optimize other economic value, such as the supply of electricity to a grid at periods of high price or high value. Curve10001represents available energy during a solar day between the beginning of the solar day and the end of the solar day. While the times of 5 AM and 8 PM are shown by way of example, it is understood that the time will vary, depending on the location and time of year. Curve10001shows the solar energy increasing from the beginning of the solar day to a maximum level and then decreasing towards the end of the solar day. Within the available solar energy, the chart illustrates that there may be multiple uses of the solar energy. As shown in the additional charts, a first use 1 and a second use 2, as explained above, are shown. Additionally, outside factors3, such as grid storage, capacity, energy supply, pricing variations due to energy markets or the like may influence the availability and demand of the solar energy for charging the thermal energy storage system. A control system, as described above, may incorporate these factors into determinations and recommendations to the operator regarding the operation of the thermal energy storage system, such as the charging and discharging of the stacks. Accordingly, the thermal energy storage system may dispatch energy for multiple purposes or uses from the output of the thermal energy storage system, while taking into account these factors. As shown in the first additional chart at scenario10007, less solar energy may be available for the thermal energy storage system later in the solar day. Alternatively, as shown in the second additional chart at10009, less solar energy may be available for charging the thermal energy storage system during the early portion and the middle to later portion of the day. Other variations may exist, as would be understood by those skilled in the art. For example, use 1 (represented by region10005) may be a local electric load in one implementation. This may represent the electricity provided to a local area by a photovoltaic array. Additionally, other uses such as use 2 (represented by region10003) may also use the available solar energy. As indicated by the shaded region, the remaining solar energy is available to charge a thermal energy storage system connect to the solar energy source exhibiting the energy profile of curve10001. In one implementation, use 2 is a second-high value use, which may be and industrial process such as electrolysis. Use 2 is then fully powered for as long as possible while excess energy beyond that needed for use 1 is available. As electricity production rises further later in the day, electricity is available for other purposes, including charging a thermal energy storage device, and/or participating in the supply of electricity, for example, to an electricity grid, where electricity may be valued at very different prices at different times. This system may be operated in such a way that, for example, electric power to a thermal storage unit may be turned off and electric power instead released to the grid as desired based upon demand, pricing or other factors, and/or power may be brought from the grid to power a storage unit or for one of other possible uses depending upon local grid conditions. Self-Sufficient Off Grid Infrastructure In some implementations, use of high voltage DC/DC conversion allows for very high efficiency connection of solar fields with suitable distance to loads such as a thermal energy storage unit that can be coupled to electrolyzers and used for electric vehicle charging. Further, a thermal energy storage system may have integrated hydrogen production in some implementations, with electric power generation from hydrogen and also have integration of lithium-ion batteries. A thermal energy storage system can also be coupled to drive desalination to produce a completely off-grid facility or military base that is self-powering for its domestic loads, its heat loads and its vehicles. Refiring of Steam Plants Since outlet temperatures from a thermal energy storage unit are higher than gas turbine outlet temperatures in some implementations, outlet from a thermal storage structure can fire the same HRSGs as a gas turbine, potentially cutting the storage unit cost by about, e.g., 40%. In some implementations, nearly all the off-specification operation of thermal plants can be reduced or eliminated by coupling to a thermal storage unit as disclosed herein. Combined cycle gas turbine (CCGT) plants were designed to run at nominal output at high capacity factor, but may not be operated in this way if connected to a power grid with variable load. In California, for example, such plants may spend significant time as “spinning reserve”—running at idle so as to be able to respond to load changes. CCGT plants may also do daily start-stop operation requiring warmup of all components to bring the plant to ready-to-operate condition and spend significant time in a “load-following” mode of throttling generation in response to load. Such reserve and warmup operations are approximately 0% fuel efficient, and there is tension between fuel cost (dictating warming the plant as fast as possible) and operations and maintenance (O&M) cost (dictating warming the plant slowly to cause less stress damage). This load-following operation in CCGT plants results in efficiency losses of at least 5% and sometimes 15%. Integrating thermal energy storage systems such as those in the example implementations disclosed herein with thermal plants may address the efficiency problems describe above. About, e.g., 90% of a plant's warmup process can be powered by intermittent renewable generation stored in a thermal storage unit. HRSG and steam turbine (ST) preheat energy is a significant factor in many plants. A “part spinning reserve” configuration can be achieved where a thermal energy storage unit fully powers the operating steam turbine, from idle to full power, so the plant can respond instantly with up to about, e.g., 40% of nominal output running completely zero-carbon, and can add then add the gas turbine (GT) in around 10 minutes. Thermoelectrochemical Converters Thermoelectrochemical converters are solid-state devices that utilize the electrochemical potential of a gas pressure applied throughout a membrane electrode assembly to convert heat into electricity via gas compression and expansion. A thermoelectrochemical converter that utilizes the electrochemical potential of a hydrogen pressure differential applied across a proton conductive membrane is known. The system consists of two membrane electrode assemblies (MEA) to convert heat into electricity via hydrogen compression and expansion. One stack is operated at a relatively low temperature and coupled to a heat sink, and the other stack is operated at a relatively high temperature and coupled to a heat source. Hydrogen gas circulates in a closed system. The net electrical power or voltage that can be achieved increases as the temperature differential between the two MEA stacks increases. Thermophotovoltaic (TPV) Cogeneration Thermophotovoltaic (TPV) energy conversion is a process of converting thermal radiation to electricity directly and includes a thermal emitter and a photovoltaic diode cell. The temperature of the thermal emitter needed varies based on system but typically ranges from about 900° C. to about 1300° C., e.g., 900° C. to 1300° C. At these TPV temperatures, radiation is radiated mostly in the form of near infrared and infrared frequencies. The photovoltaic diodes absorb some of the radiation and converts them into electricity. In art, a thermophotovoltaic cell with >29% power conversion efficiency was achieved, at an emitter temperature of 1207 C with potential for further efficiency improvement. Such a TPV system may allow for efficient cogeneration for heat and electricity. The thermal emitter may be, for example, a graphite heated by resistive heating and operated with an inert atmosphere to prevent the oxidation of graphite. Indium gallium arsenide (InGaAs) or silicon (Si) type PV cells can be used for example to generate electricity. The high temperature thermal storage system disclosed herein can be effectively coupled with a thermophotovoltaic cogeneration, offering benefits including but not limited to the following: The high temperatures combined with the storage technology matches well with high efficiency TPV systems which utilize thermal radiation to generate electricity Unlike other thermal storage systems relying largely on convective heat transfer, the “radiative echo chamber” concept described herein can work in concert with convective heat transfer to get radiation out of the thermal storage assembly or array. In one implementation, the arrays include relatively inexpensive materials with mediocre thermal transfer medium to keep costs low. The radiation chambers in effect increase the surface area from which energy can be extracted, allowing for faster discharge rates without rapidly degrading top temperatures. Extremely high storage temperatures above 2000° C. are practically achievable with a thermal storage system of the kind described herein. Such temperatures allow for the use of lower cost, more available but higher bandgap cells using silicon semiconductors for TPV. Inert gas compatible with the emitter (e.g. graphite) and TPV system can be used directly as the heat exchange fluid in the thermal storage system decreasing complexity and cost. An optional feature may include movable shields or other means to shield or block the incoming radiation at the TPV cells during the time that the thermal storage system is being charged. This allows the cells to remain cool, reduce the design cooling load and extend cell lifetime. During periods when the thermal storage system is being heated electrically coincides with periods of low cost or abundant electrical supply, making TPV operation unnecessary. In one example implementation, the lower temperature heat arising from cooling during charging and then during power generation is used for another purpose, such as steam generation, water preheating, supercritical CO2heating for power generation or for industrial process heat. This heat can be blended with hotter air coming from the storage core or segregated (e.g., introduced into another heat exchanger which e.g., supplies preheat for a process that also employs high-temperature heat, or used for another process). This would further increase the total efficiency of energy use for a combined heat and power application, examples of which are disclosed in other parts of this application, such as cement and glass production. The combination of high temperature thermal storage and TPV described herein could unlock significant value even in a pure electric power storage application. TPV can be used as a “topping” cycle and steam turbine as a “bottoming” cycle, resulting in high electricity-to-electricity efficiencies approaching 50%. The TPV component could provide “instant” services including load following, frequency and voltage regulation with rapid (e.g. millisecond) response times. The combined thermal storage-TPV system would function similarly to a lithium ion battery for part of the electric power output, providing grid stability value, with an added benefit of a long-term storage unit at a significantly lower cost and size. Thermoelectrochemical Converters Run by High Temperature Thermal Storage System As described above, the net efficiency of a thermoelectrochemical system can be increased by increasing the temperature differential between the two membrane electrode assemblies (MEA). Implementations of a thermal energy storage system disclosed herein can be coupled to the hot end of a thermoelectrochemical converter to provide near constant or constant high temperature heat. In the present example implementation, a heat exchanger in the high temperature outlet of the thermal storage system is coupled to the high temperature MEA in the thermoelectrochemical conversion system, at temperatures between 500° C. and 1200° C. The remaining heat may be used to generate steam in a Heat Recovery Steam Generator, for example, or used for another industrial application. In another example implementation, the high temperature portion of the thermoelectrochemical converter may be coupled to the heated gas from the secondary heat outlet (i.e. from cooling the high temperature energy sources) to generate electricity while the primary heat outlet (i.e., the highest temperatures, for example, at 1600° C.) is used for industrial applications such as power generation or cement production. Such cogeneration of heat and power could have combined efficiency of nearly 90% because waste heat from the thermoelectrochemical electric generation can be used for industrial purposes. In some example implementations, the environment is used as the heat sink. In other example implementations, the cool side of the thermoelectrochemical converter could use the feedwater to the HRSG as the heat sink, raising the temperature of the feedwater, recovering that energy for steam generation useful for a steam power cycle or industrial processes. Preheating of thermal exchange fluid in this way can be applied to other processes, including, for example, the cement production process. A cooled stream of CO2may first be used as the heat sink for the thermoelectrochemical converter, raising the temperature of CO2, when is then heated to operational temperatures of the cement kiln, preheater or precalciner. The heat/power balance allows retention of very high efficiency of heat and power cogeneration with high temperature heat loads for industrial processes. Electric Booster FIG.93shows an example implementation9300of the thermal energy storage system that includes an electric booster9307that is configured to boost the temperature of a fluid output to meet a requirement of an end use. In this example, electricity is provided from a source9301, such as an off-grid solar array or other VRE, to first and second thermal storage units9303,9305, referred to here as heat batteries. The electricity may be provided as DC current or AC current. While the energy source9301is shown as an off-grid renewable source of energy, and more specifically, solar photovoltaic cells, other renewable sources could be used in substitution or combination, such as wind. Further, grid electricity9302could be used in substitution or combination with the off-grid source of electricity. The electricity from the energy source9301is used to provide the electrical energy as inputs to the first and second heat batteries9303and9305, as well as for the electric booster9307. The first and TSUs9303and9305can include single stacks, double stacks or more, or some combination; the TSU's9303and9305do not have to contain the same number of stacks. In one embodiment, either or both of the TSUs9303and9305can include six stacks. The first heat battery9303can be configured to store electricity as heat, to provide heated fluid as an input to an HRSG, or to provide steam to a steam turbine9309. Alternatively, an OTSG may be used instead of the HRSG. The second heat battery9305provides hot fluid as an output for use in an industrial application, such as in a cement kiln or steel production, referred to here as a process load9311, also referred to as a drying load. It may be the heat battery9305provides the fluid at a temperature of 1000° C., which is below the drying load requirement, which for a given application may be much higher, such as 1300° C. Different fluids may be used in the first and second heat batteries9303,9305. For example, air may be used as the fluid for the first heat battery9303to power the steam turbine9309, while CO2is used as the fluid for the second heat battery9305, as needed for a particular industrial process. For example, in the case of the industrial process being a calciner, a closed loop is provided in which the fluid is recaptured for input to the heat battery9305. The temperature of the return air is such that the air does not require preheating. In other industrial applications, an open loop may be provided, such that atmospheric air9315is preheated by the condenser9313. To raise the temperature of the heated fluid to the drying load requirement, the electric booster9307is provided at the discharge of the hot fluid. Accordingly, hot fluid output from the second heat battery9305passes through the booster heater9307, and then to the process load9311, at the required temperature for the industrial process. In the second heat battery9305, the fluid may be air, CO2, or other fluid, depending on the industrial application at an output temperature, such as 1000° C.-1100° C. Further, the byproduct fluid of the industrial process may be recirculated as the input fluid to the heat battery9305, depending on the industrial process. The electric booster9307may be an electric resistance heater that boosts the fluid temperature from the maximum output of the heat battery9305to the temperature required by the process load9311. Example of the types of industrial applications that would require high temperature fluid input for the process load9311include calcining, steel production, ethylene production, and steam methane reforming of hydrogen. The electric booster9307may be an industrial electric furnace, and may optionally include fins or other structures to transfer electrical resistance heat to the air. The heaters of the electric booster may be metallic (e.g., resistive coil), ceramic or other known materials. The stream of fluid output from the first heat battery9305is heated by direct contact with the heaters of the electric booster9307. When the energy source9301is available, it may provide the electricity for the electric booster9307, as shown inFIG.93by the output line from source9301to the booster9307. For example, the solar array can provide power to the booster heater when solar energy is available. Alternatively, when solar energy is not available, or available only in limited quantity, the steam turbine9309provides all or a needed, supplemental portion of the electricity to the electric booster9307. The byproduct fluid from the steam turbine may be cooled by passing through a condenser9313, such as a cooling tower, before being condensed to a liquid state, and provided as an input to the steam generator of the heat battery9303. Optionally, the condenser9313may serve as a preheater to heat incoming air9315, for use as the input to the second heat battery9305. In other words, the condenser9313is a heat exchanger that transfers heat from the byproduct fluid (e.g., low-pressure steam) from the steam turbine9309to the input fluid9315. As a result, the input fluid to the heat battery9305is preheated. WhileFIG.93illustrates separate first and second heat batteries9303and9305, a single heat battery could instead be used. For example, hot air fluid could be streamed off and diverted from a single heat battery with multiple stacks, such that some portion of the hot fluid is provided to the process and the remainder of the hot fluid is provided to a steam generator. Such an approach might be used when the heat battery is charged from the grid, and economically optimized such that the heat battery charging is carried out at a time of low electricity prices, e.g., below some predetermined price, and the same electricity is provided to the electric booster. According to this approach, the steam turbine9309is used as a backup, on an as-needed basis. 3. Advantages Over Prior Systems Stored high-temperature energy introduced as heated air into biomass combustion and gasification processes can make substantial contributions to the effective and safe operation of such facilities. This may cause various improvements in air emissions associated both with oxides of nitrogen and unburned fuel, ability to handle biomass fuels that are wetter during certain times, as well as improvements in plant reliability and capacity factor, particularly during periods of uncertain or limited biomass supply, reductions in corrosion due to shifts in operating point, ability to operate the plant during periods of limited or no fuel ability, ability to operate the plant as an energy storage facility. Various Cogeneration Implementations Thus, in accordance with the above, a number of cogeneration system implementations are possible and contemplated, a number of examples of which are now provided. In one implementation, a cogeneration apparatus includes a thermal storage assemblage4100) including a plurality of thermal storage blocks, wherein at least some of the thermal storage blocks include multiple radiation cavities and multiple fluid flow slots, wherein some of the radiation cavities and some of the fluid flow slots are configured to define fluid pathways through the thermal storage blocks. The cogeneration apparatus further includes a plurality of heater elements positioned within the thermal storage assemblage and adjacent to at least some of the radiation cavities, wherein each of the plurality of heater elements is configured to heat at least one of the thermal storage blocks via energy radiated into multiple ones of the radiation cavities and onto surfaces that bound the respective radiation cavities. A fluid movement system is configured to direct a stream of fluid through the fluid pathways to heat the fluid to a specified temperature range, wherein the fluid movement device is configured to provide the heated fluid in the specified temperature range to a solid oxide electrolysis system configured to extract hydrogen from water and output the heated fluid at a lower temperature. A steam generator configured to receive the lower temperature fluid from the electrolysis system convert input feed water into steam. In various implementations, the steam generator is a once-through steam generator, and may also be a heat recovery steam generator. The steam generator includes a plurality of conduits coupled to receive the input feed water, wherein selected ones of the conduits are arranged to mitigate scale formation and overheating. In certain implementations, ones of the plurality of conduits are arranged in the steam generator transversely to a path of flow of the lower temperature fluid. The thermal storage assembly comprises an enclosure containing the plurality of thermal storage blocks and a thermal barrier separating a first subset of the plurality of thermal storage blocks from a second subset of the plurality of thermal storage blocks. The fluid movement system is configured to direct the stream of fluid through the fluid pathways of one of the first and second subsets of thermal concurrent with an electricity source adding heat to another one of the first and second subset. In some implementations, the fluid comprises oxygen and nitrogen. Various sources of electricity may be used to charge the thermal storage assemblage. In one implementation, the thermal storage assemblage is configured to store thermal energy generated by a conversion of input electricity from an first input energy supply, the first input energy supply having intermittent availability. Implementations are further contemplated in which the thermal storage assemblage is further configured to store thermal energy generated by a conversion of input electricity from an second input energy supply configured to provide electricity on demand. In yet another implementation, a cogeneration apparatus includes a thermal storage assemblage having a plurality of thermal storage blocks, wherein at least some of the thermal storage blocks include multiple radiation cavities and multiple fluid flow slots, wherein some of the radiation cavities and some of the fluid flow slots are configured to define fluid pathways through the thermal storage blocks. The implementation further includes a plurality of heater elements positioned within the thermal storage assemblage and adjacent to at least some of the radiation cavities, wherein each of the plurality of heater elements is configured to heat at least one of the thermal storage blocks via energy radiated into multiple ones of the radiation cavities and onto surfaces that bound the respective radiation cavities. A fluid movement system is configured to direct a stream of fluid through the fluid pathways to heat the fluid to a specified temperature range. A steam generator is configured to receive the fluid to convert input feed water into input steam having a first pressure. A steam turbine configured to receive the input steam and provide output steam at a second pressure that is less than the first pressure. Such implementations may further include a second fluid movement device configured to move the output steam to an industrial plant for use in an industrial process. The steam generator, in various implementations, is a once-through steam generator. The steam generator includes a plurality of conduits coupled to receive the input feed water, wherein selected ones of the conduits are arranged to mitigate scale formation and overheating. Ones of the plurality of conduits are arranged in the steam generator transversely to a path of flow of the lower temperature fluid. With regard to the industrial process, a number of different processes are possible and contemplated. In one implementation, the industrial process comprises producing petroleum-based fuels. In another implementation, wherein the industrial process comprises producing biofuels. In yet another implementation, the industrial process comprises producing diesel fuels. In still a further implementation, the industrial process comprises drying grains. These industrial processes are provided here as examples, and do not constitute an exhaustive list of possible industrial processes that may be used with the various implementations. The present disclosure contemplates a wide variety of industrial processes beyond the examples given here. It is further noted that implementations are possible and contemplated wherein the steam turbine is configured to cause an electrical generator to provide electricity to the industrial process. In yet another possible implementation, a cogeneration apparatus includes a thermal storage assemblage having a plurality of thermal storage blocks, wherein at least some of the thermal storage blocks include multiple radiation cavities and multiple fluid flow slots, wherein some of the radiation cavities and some of the fluid flow slots are configured to define fluid pathways through the thermal storage blocks. A plurality of heater elements is positioned within the thermal storage assemblage and adjacent to at least some of the radiation cavities, wherein each of the plurality of heater elements is configured to heat at least one of the thermal storage blocks via energy radiated into multiple ones of the radiation cavities and onto surfaces that bound the respective radiation cavities. A fluid movement system is configured to direct a stream of a first fluid through the fluid pathways to heat the first fluid to a specified temperature range. A first steam generator is configured to, using the first fluid, convert input feed water into steam. A steam turbine configured to cause generation of electricity using the steam. The implementation also includes a preheater configured to, using waste heat from the steam turbine, preheat feed water provided to a second steam generator. In an implementation, the first steam generator is a heat recovery steam generator, and may also be (or alternatively be) a once-through steam generator. Various implementations also include a condenser coupled to the steam turbine, wherein the condenser is configured to condense steam received from the steam turbine into water a recirculation pump configured to provide, as feed water to the first steam generator, water produced by the condenser. The second steam generator in various implementations is configured to generate steam using a second fluid from a second storage medium configured to store thermal energy. The preheater in various implementations is configured to output a third fluid to the thermal storage assemblage. A further implementation of a cogeneration apparatus includes a thermal storage assemblage) including a plurality of thermal storage blocks, wherein at least some of the thermal storage blocks include multiple radiation cavities and multiple fluid flow slots, wherein some of the radiation cavities and some of the fluid flow slots are configured to define fluid pathways through the thermal storage blocks. A plurality of heater elements is positioned within the thermal storage assemblage and adjacent to at least some of the radiation cavities, wherein each of the plurality of heater elements is configured to heat at least one of the thermal storage blocks via energy radiated into multiple ones of the radiation cavities and onto surfaces that bound the respective radiation cavities. A fluid movement system is configured to direct a stream of fluid through the fluid pathways to heat the fluid to a specified temperature range. A steam generator is configured to receive the fluid to convert input feed water into input steam. Various implementations also include a measurement unit configured to determine a measured steam quality value of steam output from the steam generator. A controller is configured to cause the cause the fluid movement system to direct the stream of fluid, and further configured to use the measured steam quality as feedback to adjust a flow rate of the fluid to maintain the measured steam quality within a specified steam quality range. In some implementations, the measurement unit includes a separator configured to separate steam output from the steam generator from water vapor output from the steam generator, wherein the measurement unit is configured to determine the measured steam quality based on fraction of the water vapor output from the steam generator relative to the steam output from the steam generator. Implementations are further possible and contemplated in which the measurement unit is configured to determine the steam quality based on a flow velocity of steam output from the steam generator and a mass flow rate of the input feed water. With regard to the steam generator, implementations are possible and contemplated in which the steam generator is a once-through steam generator. The controller of such implementations may be configured to cause delivery of steam in accordance within a specified range of steam delivery rates. Accordingly, the controller is configured to specify the range of steam delivery rates based on forecast information. Various types of forecast information are possible and contemplated as a basis for the controller to specify the range of steam delivery rates. In various implementations, the forecast information includes weather forecast information. Implementations in which the forecast information includes expected electricity rates are also possible and contemplated. Similarly, implementations in which the forecast information includes expected steam demand are contemplated. It is noted that the controller may use one or more types of the forecast information mentioned here, while other types of forecast information not explicitly discussed herein may also be used in various implementations. In still another implementation, a cogeneration system includes a storage medium configured to store thermal energy generated by a conversion of input electricity from an input energy supply, the input energy supply having intermittent availability. A fluid movement device is configured to move fluid through the storage medium to heat the fluid to a specified temperature, the fluid comprising oxygen and nitrogen, wherein the fluid movement device is configured to provide the fluid at the specified temperature to a solid oxide cell electrolysis system that converts water to hydrogen and enriches the fluid with oxygen. Such implementations may also include a once-through steam generator configured to, using the fluid received from the electrolysis system convert input feed water into steam. These implementations may further include a steam turbine configured to cause an electrical generator to generate of electricity using steam received from the steam generator. With regard to thermal storage, the thermal storage unit may comprise a plurality of bricks. A controller in an implementation is configured to cause the fluid movement device to move fluid at a particular rate. Further contemplated in various implementations is a measurement unit configured to measure a parameter of steam output from the steam generator. The controller is configured to adjust the particular rate based on the measurement of the parameter of steam output. Meanwhile, the measurement unit in various implementations comprises a separator configured to measure a quality of the steam output from the steam generator by separating the steam into a liquid phase and a vapor phase. Alternatively, implementations in which the measurement unit is configured to measure a velocity of steam output from the steam generator are also possible and contemplated. The controller is configured to control an amount of fluid moved through the storage medium based on a weather forecast. The controller may also be configured to control and amount of fluid moved through the storage medium based on an expected difference in electricity costs on a first day and a second day. Various types of electrical sources may comprise the intermittent energy supply in various implementations. In one implementation, the intermittent energy supply comprises a thermophotovoltaic generation system configured to convert thermal radiation into electrical energy. The intermittent energy supply may also, or alternatively, comprise a wind turbine configured to generate electricity. The intermittent energy supply may also a solar energy source configured to convert solar energy into electricity, which may be used singularly or with various ones of the other types mentioned herein. The fluid movement device in one implementation comprises a closed fluid recirculation loop. Implementations may a pump, and wherein the pump is configured to force the input feed water through one or more conduits of the steam generator. With regard to the steam generator, one or more conduits may be provided in which feed water flows. In such implementations, the one or more conduits may be mounted in the steam generator transversely to a path fluid flow. In yet another implementation, a cogeneration system include a storage medium configured to store thermal energy generated by a conversion of input electricity from an input energy supply, the first input energy supply having intermittent availability. A first fluid movement device is configured to move fluid through the storage medium to heat the fluid to a specified temperature. A once-through steam generator is configured to, using the fluid, convert input feed water into an input steam having a first pressure. The system may include a steam turbine configured to provide an output steam at a second pressure that is less than the first pressure. A second fluid movement device may in various implementations is configured to move the output steam to an industrial plant for use in an industrial process. The steam turbine in various implementations is configured to cause generation of electricity by an electrical generator. The electrical generator is configured in some implementations to provide electricity to a power grid. Various types of industrial processes are possible and contemplated in accordance with the above. In one implementation, the industrial process comprises production of biofuels. In another implementation, the industrial process comprises production of petroleum-based fuels. In yet another implementation, the industrial process comprises production of diesel fuels. Implementations in which the industrial process comprises drying of grains are also possible and contemplated. The disclosure contemplates industrial processes other than those measured here that may also benefit from use of an implementation of the cogeneration system/apparatus per this disclosure. The cogeneration system in various implementations includes a controller configured to cause the steam generator to generate steam at a specified steam quality based on steam quality. The steam quality may be calculated by a comprising a measurement unit configured to determine the steam quality based on separation of steam and water vapor output from the steam generator. In another implementation, the steam quality may be calculated by a measurement unit configured to determine the steam quality based on measurements of steam outlet flow and feed water input flow. The steam quality may, in various implementations, be affected by the rate at which fluid is moved through the storage device. Accordingly, implementations are possible an contemplated in which the controller is configured to control a rate at which fluid is moved through the storage medium by the first fluid movement device. In some implementations, the storage medium comprises a plurality of bricks. Yet another implementation of a cogeneration system includes a first storage medium configured to store thermal energy generated by a conversion of input electricity from an input energy supply, the input energy supply having intermittent availability. The system further includes a fluid movement device configured to move fluid through the storage medium to heat the fluid to a specified temperature. A first steam generator is configured to, using the fluid, convert first input feed water into steam. A steam turbine is configured to, using the steam, cause an electrical generator to generate electricity. Implementations may further include a preheater configured to, using waste heat from the steam turbine, preheat second feed water provided to a second steam generator. The steam generator in one implementation is a once-through steam generator. However, implementations in which the steam generator performs at least some recirculation of feed water are also possible and contemplated. Accordingly, some implementations include a condenser configured to receive at least a portion of the steam from the steam turbine and configured to condense the portion of steam into third feed water, while a recirculation pump is configured to provide the third feed water to the first steam generator. In various implementations, the steam generator is a heat recovery steam generator. The measurement of steam quality output by the steam generator may be performed in various implementations, which may thus include a measurement unit configured to determine a measured output steam quality and a controller configured to adjust a current output steam quality to within a specified range using the measured output steam quality as feedback. In such implementations, the controller is configured to cause fluid movement device to adjust a rate of fluid flow through the storage medium in accordance with the feedback and the specified range of steam quality. D. Carbon Removal 1. Problems to be Solved Carbon dioxide is the largest contributor to global greenhouse gas emissions, with fossil fuel use being the primary source of carbon. About 20% of emissions come from industrial processes, which primarily involve fossil fuel combustion for energy. In the U. S. alone, greenhouse gas emissions totaled 6,577 million metric carbon tons of carbon dioxide equivalents. At least 16 states and Puerto Rico have enacted legislation establishing reduction requirements for greenhouse gas (GHG) emissions. California, for example, has implemented GHG emissions reduction targets through SB32, which requires that the state Air Resource Board (CARB) ensure GHG emissions reductions to 40% below 1990 levels by 2030. These forces, combined with falling renewable energy prices, have driven a boom in renewables adoption, thus increasing the challenge of balancing energy supply and demand with added intermittent energy supply. Renewable energy curtailment has steadily increased, and oversupply conditions are expected to occur more often going forward. At the same time, in order to respond quickly to sudden losses of generation and/or unexpected changes in load, there may be greater need for expensive spinning and other operating reserves. In addition, the energy produced through renewable means, for example, solar and wind, typically does not match the demand. Accordingly, the value of efficient solutions for energy storage has become increasingly clear in order to continue increasing renewable fraction in our energy supply. Energy storage is able to provide backup power or heat when traditional sources of energy (e.g., grid electricity) are lost or interrupted. Energy stored as high temperature heat has multiple advantages, including higher energy density, lower cost, increased flexibility for use in industrial high temperature applications as well as for producing power. Decarbonization may be particularly difficult for industrial processes requiring very high temperatures, such as above 1000° C. Existing industrial heat processes are generally fired by fossil fuels, sometimes with enriched oxygen atmosphere for applications requiring very high temperatures, for example greater than 1500° C. Such processes cannot be switched to an intermittent renewal source because of the need for continuous, high temperature heat. Meanwhile, some governments around the world limit greenhouse gas emissions. For example, in Europe, the EU emissions trading system (EU ETS) uses a cap-and-trade method to limit carbon emissions. Carbon dioxide prices are expected to significantly increase in the future. At the end of 2019, the average price of carbon dioxide in Europe was €25/ton. Germany has announced prices in the range of €55-65 per ton after 2026 and by 2050, carbon dioxide prices in the range of €100-€150 per ton is expected. In the European cement industry alone, which emitted 117 megatons of CO2in 2018, the current cost of the emission is approximately €3 billion. Globally, energy-related CO2emissions were around 33 gigatons in 2019. Therefore, there is significant unmet need for technologies that can significantly reduce carbon emissions in industry, such as using renewable electricity. However, for very high temperature operations such as cement, glass, power and steel production, there are no reliable ways to achieve the high temperatures needed by using only intermittent energy sources. Processes for separating carbon dioxide gas from exhaust gases that are generated by combustion of fuels may require a continuous flow of heat and electricity. Exhaust gases may increase during time periods of high demand, when generated electricity costs are highest, and therefore, not desirable for use in a carbon capture process. Alternatively, use of renewable sources of electricity are intermittent, and therefore not reliable for generating the required continuous flow of heat and electricity. It is noted that use of “continuous source of heat and electricity” is not intended to imply zero variation in temperature and/or electrical power. Rather the term “continuous,” as used herein, indicates that the source of heat and/or electricity are capable of providing a sufficient amount of electricity and heat to maintain proper operation of a carbon dioxide separation process. Calcium Looping is one example of a CO2capture technology that is based on cyclic calcination/carbonation reaction of, for example, CaO. CaO reacts with CO2to generate CaCO3. The forward reaction is called carbonation, and is exothermic, where CO2is captured onto the sorbent. The reverse reaction, calcination, is endothermic and releases a pure stream of CO2which can be captured, compressed and stored. Such a cycle may include an intermediate step of hydration to increase the cycle life of the sorbent. The calcination reaction (releasing of CO2) requires high temperatures above 900° C. whereas the carbonation reaction (adsorption of CO2) requires temperatures around 600-700° C. Intermediate hydration reactions may occur at temperatures 100-200° C. While calcium looping with CO2and sometimes other gases such as SO2 is an important technology to decrease the carbon footprint, the large energy requirement, often met by burning fossil fuels in a pure stream of oxygen, poses additional challenges toward reducing the carbon intensity of the process. There is an unmet need for a high temperature thermal energy storage system powered by renewable electricity that can provide the energy required to run such a process, making the calcium looping process carbon negative. 2. Carbon Capture While calcium looping offers promising methods for capturing and storing CO2, the requirement in existing technologies for high temperature heat provided by a fuel stream combined with pure oxygen reduces the overall carbon capture efficiency. Such technologies may further require an air separator which adds cost and complexity to the system. The problem of generating constant power and heat from an intermittent power source for use in a calcium-looping carbon dioxide separation process may be resolved by charging thermal storage units when the intermittent power source is available and generating the heat and power from the thermal storage units. Use of such thermal storage units may allow for continuous generation of heat and electricity from an inconsistent power source. Referring toFIG.94, a high temperature thermal energy storage system powered by renewable electricity disclosed herein which uses some of the CO2generated as the thermal exchange fluid running through an example implementation system100eliminates the need for additional fuel or a pure oxygen stream. High temperature heat can be used for the regeneration cycle, mid-range temperature heat for the carbonation cycle, and low temperature heat can be used for the hydration reaction or to pre-heat the CO2stream entering the storage system. A truly carbon-negative calcium looping process can be coupled to any CO2producing processes and may have particular benefit in the cement production industry which can use spent calcium oxide to augment feedstock into the cement production process. One application of the heated brick storage system is to drive a cryogenic carbon removal process. In one case, the unit is used to power a continuous electric power generation source which in turn drives a carbon dioxide separation process, which uses cryogenic effects, compressing and cooling CO2to reduce its temperature until it becomes a solid, or in some embodiments a liquid. A supply of the electrical energy needed to drive that process is derived from energy supplied by a turbine generator whose input heat can be provided by a thermal energy storage unit. Many carbon capture processes, such as calcium looping, rather than purely using electric power (like the cryogenic process described above) also use thermal energy. The thermal energy may be used to regenerate a solid or liquid medium which captures carbon dioxide, then releases it (by being regenerated), and then is used again for one or more cycles to capture further carbon dioxide. Thermal energy from a heat storage unit described above can provide renewable based energy for this process. High temperature heat may drive one implementation of a calcination process, in a multi-step chemical reaction which involves the repeated conversion of a calcium oxide to calcium carbonate using captured carbon dioxide, and then calcination to release the carbon dioxide. Such reactions take place at high temperatures, and high temperature heat from a heat storage unit described above can power this process, followed by the use of the remaining lower temperature heat to drive an electrical generator, via a turbine heat-to-work process, including steam, CO2or Rankine cycle processes. Such heat may be supplied as lower grade heat from the outlet of a turbine generator, into which high grade heat is supplied by a thermal storage unit, such that some portion of energy is used in the form of electricity to drive pumps, and another portion of energy, in the form of heat, is used to drive regeneration. Both forms of energy may be supplied in an efficient manner using high temperature thermal energy storage. Referring toFIG.94, in some example implementations, the integrated cogeneration system400can be configured to provide thermal and electrical energy necessary to drive a carbon capture and sequestration process. The processes of CO2separation from exhaust gases and CO2capture directly from ambient air (Direct Air Capture, or DAC) commonly use processes where a capture media, which may be an absorbent liquid, an adsorbent solid, or a chemically reactive solid is exposed to flue gas or other CO2-containing gas streams at a first temperature, then heated to a second temperature which causes the selective release of the CO2into another fluid conduit, followed by a cooling of the capture media and its re-use in another cycle of capture and release. Stored thermal energy derived from VRE may provide a continuous supply of the necessary heat to drive this process. High-temperature air, or other type of fluid, may be directed to calcine or otherwise regenerate a high-temperature capture media. In one, steam may be directly supplied by an HRSG to drive a capture process element such as an amine solvent reboiler or adsorbent regenerator. In addition, or in place of steam from an HRSG, lower-pressure extracted steam from a steam turbine power cycle may be directed to provide heat to a solvent reboiler. Electrical power generated by a steam turbine, organic Rankine cycle turbine, or supercritical CO2turbine may provide electric power to drive the CO2capture and compression equipment. Thus stored VRE may provide all energy necessary to drive a zero-emission carbon capture system702to enable separation of CO2from exhaust gases or ambient air. One example of using thermal storage units in a carbon capture process includes a carbon dioxide capture system that is configured to separate carbon dioxide from exhaust gases using, for example, a calcium looping process as described above. FIG.100illustrates a direct air capture approach11000according to the example implementations. A thermal storage system is included that is configured to convert input electricity from an input energy supply to stored thermal energy, the input energy supply having intermittent availability, e.g., from VRE11001, such as a renewable energy source. The example further includes a power generation system, including thermal energy storage11003that provides hot fluid to an HRSG11007, that is configured to convert the stored thermal energy to output electricity. This output electricity is provided to the carbon dioxide capture system. The carbon dioxide capture system is configured to operate using the provided electricity. In some embodiments, the thermal storage system includes a thermal energy storage11007that is configured to heat a storage medium using the input electricity from the input energy supply (VRE11001), as well as a blower that is configured to circulate fluid through the heated storage medium, as explained above. The power generation system, in some embodiments, may include a heat exchanger that is configured to generate steam using circulated fluid, and a steam turbine that is configured to generate the supplied electricity from the produced steam. The carbon dioxide capture system may include thermal energy storage11005, which is configured to use a portion of stored thermal energy as heat to separate the carbon dioxide from the exhaust gases. For example, the heat may be used as part of a calcination cycle at calciner11009used to release carbon dioxide from an adsorbent material that has been used to capture the carbon dioxide. The thermal energy storage system, in some implementations, is configured to generate the output electricity in a substantially continuous manner, thus allowing the carbon dioxide capture system to be operational as needed. An example method for operating a thermal energy storage system is presented inFIG.95. Method5100includes, at block5110, converting, by a thermal energy storage system, input electricity from an intermittently availability energy supply to stored thermal energy. For example, a renewable energy source, such as solar or wind, may be used to generate electricity which, in turn, is used to power heating elements that supply heat to a storage medium. At block5120, method5100includes providing stored thermal energy from the thermal energy storage system to a steam turbine to generate electricity. The heated storage medium may be used to supply heat to a boiler that drives an electricity generator (e.g., a steam-powered generator). Heat may be transferred, via a suitable fluid, from the storage medium to a heat exchanger that heats the boiler. Method5100further includes, at block5130, providing the generated electricity and heat from the thermal energy storage system to a carbon dioxide capture system that separates carbon dioxide from exhaust gases, wherein the output electricity and heat is provided at least at times when the energy supply is not available. Any suitable type of carbon dioxide capture process, such as a calcium looping process or cryogenic process, may be used. Use of a thermal storage system may allow the stored heat to be used at times when the energy source is not available, in addition to times when the energy supply is available. An example method for operating a carbon dioxide capture system is shown inFIG.96. Method5200includes, at block5210, receiving, by a carbon dioxide capture system, exhaust gases from combustion of a fuel source. The carbon dioxide capture system may include an absorber tower through which, exhaust gases flow, the exhaust gases coming from a furnace that is used to burn fossil fuels. At block5220, method5200further includes receiving, by the carbon dioxide capture system, electricity generated from a thermal energy storage system. In the present example, power for the carbon dioxide capture system is provided by an intermittent source, such as renewable energy sources. The thermal energy storage system stores thermal energy using the intermittently availability energy supply. Method5200further includes, at5230, separating, by the carbon dioxide capture system, carbon dioxide from exhaust gases using the received electricity and heat. Any suitable type of carbon dioxide capturing process may be used, including the processes disclosed herein. In some implementations, the carbon dioxide capture system may use both electricity and heat from the thermal energy storage system. The separating is performed at least at times in which the energy supply is not available. Since an intermittent energy source is used to supply the thermal energy storage system, this thermal energy storage system is capable of providing continuous heat to be used by the carbon dioxide capture system as a heat source and/or to generate electricity. 3. Advantages of Disclosed Implementations The example implementations related to carbon capture may have various advantages and benefits relative to traditional techniques. For example, the approaches described herein may address oversupply issues, as well as promote additional carbon capture for very high temperature industrial applications. For example, use of thermal storage units may allow use of electricity generated by the combustion of fuels. During time periods of low electricity demand, power generated from combustible fuels is used to charge thermal storage units. During time periods of high electricity demand, charging of the thermal units is ceased and the carbon capture process is powered by the charged thermal storage units. Accordingly, the thermal units may be charged when electricity costs are low and the produced electricity, therefore, has less value. During the time periods of high electricity demand, the produced has greater value and can be sold to an electrical grid rather than being routed to the carbon capture process. E. Additional Industrial Applications 1. Renewable Desalination Desalination processes traditionally run continuously and a significant amount of the world's desalination currently comes from membrane systems. The vast majority of the desalination in some regions (e.g., the Middle East), however, uses older thermal desalination technology that is coupled to a combined cycle power station. The combined cycle power station may have a combustion turbine and a steam turbine which outputs, for example, 70° C. condensation, which powers either a multi-stage flash or a multi-effect distillation production system. This may reduce the steam turbine electricity output by a few percent but may significantly reduce the electricity used to make water by desalination. In one example one ton of input steam makes four tons to seven tons of output water. In some use cases, the power station remains running to keep desalination operational even when there is no other demand for the electricity generated by the power station, which results in power being wasted. With more renewable energy coming online, this may be an increasingly pressing problem. By incorporating a heat storage system in accordance with example implementations, these problems may be addressed. The heat storage system may have an outlet temperature hotter than the outlet temperature of the combustion turbine. Thus, the heat storage system may be connected to a heat recovery steam generator with a separate air inlet port, or a steam generator of the heat storage system may be run to make water, firing no natural gas. The heat storage system may be charged by PV or run from grid power to absorb what would otherwise be over generation in the daytime and transition to true zero carbon water. Thus, this system may be used to buffer peak electricity and provide level load power. If the combustion turbine is not been de-installed, during periods of high electricity demand, such as during a hot summer day, the combustion turbine remains available and thermal storage can be additionally deployed to run the steam turbine above nominal if desired. One challenge in certain geographical regions (e.g., in the Middle East) is that a combustion turbine may produce around 18% less electricity on a hot day than it would on a cold day due to the lower combustion air density on the hot day. The disclosed heat storage system may be used to bring this steam mass flow and/or temperature back up when power from the turbine is drooping. All that can be electric so base load water can be made, but also includes its built-in topping power for peak electricity demand. The heated brick energy storage systems described herein may be capable of producing higher output temperatures which may allow direct integration into existing desalination systems or may serve as the basis for a dedicated desalination system. One beneficial element of these heated brick heat storage systems is that they may be retrofitted into existing plants to capture what would otherwise be overgeneration in the system. It should be noted that the disclosed heat storage system, coupled with a combined cycle power station can also drive a reverse osmosis system or other industrial processes, which may require round the clock power, with renewable energy. 2. Glass Production Glass production typically requires temperatures ranging from 1500-1700° C. in a melting furnace where raw materials transform through a sequence of chemical reactions to form molten glass. The melting process represents over half of energy use in glass production. The metal bath may require temperatures from 1100° C. to around 600° C. at the outlet before the molten glass is annealed at 600° C. In some traditional implementations, the thermal energy required for glass production is provided by fossil fuel combustion and in some cases, electrical heating. Glass production is thus a highly energy-intensive process and global demand continues to increase for glass. According to the International Energy Agency, the container and flat glass industries (which combined account for 80% of glass production) emit over 60 megatons of CO2per year (IEA 2007) and energy use accounts for about 15% of total glass production costs. Glass melting furnaces are complemented by a set of heat recovery regenerators which recover heat from the end of a melt furnace and use it to pre-heat the combustion air, e.g., to 900-1200° C. prior to the temperature being raised further through the burner to about 1700° C., e.g., 1700° C. The high temperature energy storage system disclosed herein may have the capability to provide all thermal needs of the glass production system, including the high temperature melt furnace. In one example implementation, glass regenerators can be replaced by high temperature thermal energy storage systems disclosed herein to provide high temperature air or another gas and eliminate the need for a burner. Because glass production is a round-the-clock process, an energy storage system may be used in one implementation to replace a significant amount of the input energy with intermittent renewable energy. The reduction or elimination of combustion gases may also reduce the amount of undesirable combustion products in the glass furnace. Nitrogen or another gas can be used in a closed loop through the high temperature thermal energy storage system, and into the float tank, reducing cost of air separation and reducing the production of undesirable side product of nitrogen oxides (NOx) produced by thermal reaction of nitrogen and oxygen in air. In an alternative example implementation, the heated air from existing regenerators can be fed into the high temperature thermal energy storage system disclosed herein which then produces output fluid at a temperature utilized by the melt furnace. This may also reduce or eliminate need for a burner and additional combustion of fossil fuels. 3. Iron and Steel Production Traditionally, crude steel is made using blast furnaces. Steelmaking may require high temperatures, such as approximately 1600° C., e.g., 1600° C. Every ton of steel produced in 2018 emitted on average 1.85 tons of carbon dioxide including agglomeration, iron- and steelmaking, casting and hot rolling, and accounts for approximately 30% of the global industrial CO2emissions. Therefore, there is a substantial unmet need for reduction of the carbon intensity of steelmaking. The European steel industry aims to reduce CO2emission by 80-95% by 2050 to meet the requirements of the Paris Agreement. Such drastic reduction may be difficult or impossible to achieve using traditional equipment. Direct reduction processes used with an electric arc furnace may provide a pathway for substantial CO2emission reduction in the steel industry. Use of natural gas as the reducing agent reduces CO2emissions by approximately ⅓ compared to the traditional blast furnace route. Using renewable H2as a reducing agent further reduces emissions. However, the process may be thermally unfavorable due to the endothermic nature of the reaction between hydrogen and iron oxide. For example, 800 m{circumflex over ( )}3 (STP)/t DRI (cubic meters at standard temperature and pressure per metric ton of direct reduced iron) of hydrogen may be necessary for operation with hydrogen alone. The reduction process itself needs 550 m{circumflex over ( )}3 (STP)/t DRI, whereas 250 m{circumflex over ( )}3 STP/t DRI of hydrogen is required as fuel for the gas heater. An additional −50 m{circumflex over ( )}3(STP)/t DRI of natural gas may be needed in order to maintain the temperature and carbon content of the DRI. The temperature reduction from the hydrogen reaction can be compensated by the addition of natural gas. The exothermic reaction is between iron oxide and CO. In comparison, natural gas process requires approximately 259 m{circumflex over ( )}3 STP/t DRI. The ultrahigh temperatures produced by the thermal energy storage system of the example implementations may reduce carbon emissions from the steelmaking process. The ability to obtain some of the highest temperatures of the steelmaking operation near 1600-2000° C. means that thermal process heat needs in the blast furnace can be met using a renewable-energy-charged thermal storage system around the clock as described above. In addition, the gas composition heated inside the thermal storage unit may be tuned/selected to further increase production efficiency, to retrofit fossil fuel systems to a direct reduction process without the need for significant equipment modification, or both. In other words, a traditional system may be relatively simply retrofitted to be electrified using intermittent electricity sources such as a PV system. For example, hydrogen or natural gas can directly be used as the heat exchange fluid which is heated by the thermal storage system and also to directly reduce the ore into steel. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing. For example, the following terminology may be used interchangeably, as would be understood to those skilled in the art:A AmperesAC Alternating currentDC Direct currentDFB Dual Fluidized BedEAR Enhanced Oil RecoveryEV Electric vehicleGT Gas turbineHRSG Heat recovery steam generatorkV kilovoltkW kilowattMED Multi-effect desalinationMPPT Maximum power point trackingMSF Multi-stage flashMW megawattOTSG Once-through steam generatorPEM Proton-exchange membranePV PhotovoltaicRSOC Reversible solid oxide cellSOEC Solid oxide electrolyzer cellSOFC Solid oxide fuel cellST Steam turbineTES Thermal Energy StorageTSU Thermal Storage Unit Additionally, the term “heater” is used to refer to a conductive element that generates heat. For example, the term “heater” as used in the present example implementations may include, but is not limited to, a wire, a ribbon, a tape, or other structure that can conduct electricity in a manner that generates heat. The composition of the heater may be metallic (coated or uncoated), ceramic or other composition that can generate heat. While foregoing example implementations may refer to “air”, including CO2, the inventive concept is not limited to this composition, and other fluid streams may be substituted therefor for additional industrial applications. For example but by way of limitation, enhanced oil recovery, sterilization related to healthcare or food and beverages, drying, chemical production, desalination and hydrothermal processing (e.g. Bayer process.) The Bayer process includes a calcination step. The composition of fluid streams may be selected to improve product yields or efficiency, or to control the exhaust stream. In any of the thermal storage units, the working fluid composition may be changed at times for a number of purposes, including maintenance or re-conditioning of materials. Multiple units may be used in synergy to improve charging or discharging characteristics, sizing or ease of installation, integration or maintenance. As would be understood by those skilled in the art, the thermal storage units disclosed herein may be substituted with other thermal storage units having the necessary properties and functions; results may vary, depending on the manner and scale of combination of the thermal storage units. As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise. The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided with respect to certain example implementations herein is intended merely to better illuminate the example implementation and does not pose a limitation on the scope of the example implementation otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the example implementation. Groupings of alternative elements or example implementations of the example implementation disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims. In the specification, reference may be made to the spatial relationships between various components and to the spatial orientation of various aspects of components as the devices are depicted in the attached drawings. However, as will be recognized by those skilled in the art after a complete reading of the present application, the devices, members, devices, etc. described herein may be positioned in any desired orientation. Thus, the use of terms such as “above,” “below,” “upper,” “lower,” “first”, “second” or other like terms to describe a spatial relationship between various components or to describe the spatial orientation of aspects of such components should be understood to describe a relative relationship between the components or a spatial orientation of aspects of such components, respectively, as the device described herein may be oriented in any desired direction. In interpreting the specification, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C . . . and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc. While the foregoing describes various example implementations of the example implementation, other and further example implementations of the example implementation may be devised without departing from the basic scope thereof. The scope of the example implementation is determined by the claims that follow. The example implementation is not limited to the described example implementations, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the example implementation when combined with information and knowledge available to the person having ordinary skill in the art. Subject Matter of Claims for Future Examination Following are sets of claims relating to various embodiments according to the present disclosure. Claim set 1 matches the set of claims 1-56 as filed herein for examination. Claim sets 2-7 include independent claims matching the independent claims as filed herein for examination beginning with claim 57. The dependent claims in claim sets 2-7, and claims sets 8-9, are reserved for examination in future applications. The claims below can be grouped as follows: Claims 1-56 include, inter alia, claims relating to physical structures of systems according to the present disclosure including bricks, stacks, heating apparatus, radiation chambers and related structures and processes, including once-through steam generators. Claims 57-297 include, inter alia, claims relating to control processes, method and structures, including those relating to charging, discharging, deep discharging, and integrations of systems with variable renewable electricity systems and industrial processes. Claims 298-321 include, inter alia, claims relating to electronic designs and processes for systems according to the present disclosure, including DC-DC conversion systems and techniques. Claims 322-352 include, inter alia, claims relating to application of systems and methods according to the present disclosure to calcining and other industrial processes. Claims 353-594 include, inter alia, claims relating to application of systems and methods according to the present disclosure to solid-state electrolysis systems and processes. Claims 595-629 include, inter alia, claims relating to application of systems and methods according to the present disclosure to cogeneration systems. Claims 630-635 include, inter alia, claims relating to application of systems and methods according to the present disclosure to selective application of discharge energy to different uses and processes based upon demand and other criteria. Claim 636 describes various specific components and characteristics of a TES system. Claims 637-643 include, inter alia, claims relating to application of systems and methods according to the present disclosure to carbon capture processes. Introductory comments are provided to some of the claims below to highlight features and advantages of those claims. Bricks with radiation chambers: Radiative heating via radiation cavities and convective discharging/heating via air movement, as well as internal conduction, more evenly distributes heat through the assemblage of blocks. 1. A system for thermal energy storage and delivery, comprising:a thermal storage assemblage (4100) including a plurality of thermal storage blocks, wherein at least some of the thermal storage blocks include multiple radiation cavities and multiple fluid flow slots, wherein some of the radiation cavities and some of the fluid flow slots are configured to define fluid pathways through the thermal storage blocks;a plurality of heater elements (3607) positioned within the thermal storage assemblage and adjacent to at least some of the radiation cavities, wherein each of the plurality of heater elements is configured to heat at least one of the thermal storage blocks via energy radiated into multiple ones of the radiation cavities and onto surfaces that bound the respective radiation cavities; anda fluid movement system (213,4223) configured to direct a stream of fluid through the fluid pathways. Radiation in a Direction Different from Fluid Movement. 2. The system of claim 1, wherein at least some of storage blocks are positioned such that heater elements positioned adjacent to some of the radiation cavities emit heat primarily in a radiation direction that is different than a fluid flow direction through corresponding fluid pathways. 3. The system of claim 2, wherein the radiation direction is substantially orthogonal to the fluid flow direction. Fluid Pathways Oriented in a Vertical Direction. 4. The system of claim 2, wherein the fluid flow direction through the fluid pathways is substantially vertical and at least some of the heater elements are horizontally adjacent to some of the radiation cavities. 5. The system of claim 2, wherein the heater elements, the storage blocks and the radiation cavities are configured to provide a substantially vertical thermocline wherein an upper portion of the thermal storage assemblage is at a higher temperature than a lower portion of the thermal storage assemblage. Each Radiative Cavity Having Multiple Slots. 6. The system of claim 1, wherein at least one of the fluid pathways includes multiple fluid flow slots that open to a particular radiation cavity and the stream of fluid passes through the multiple fluid flow slots from the particular radiation cavity. Alternating Cavities. 7. The system of claim 1, wherein a fluid pathway includes multiple cavities and multiple fluid flow slots, is oriented for substantially vertical fluid flow, and includes alternating radiation cavities and sets of one or more fluid flow slots in the vertical direction. Slots May Receive Radiation Indirectly. 8. The system of claim 1, wherein the fluid flow slots are positioned such that radiative energy from the heater elements arrives at the fluid flow slots indirectly by reradiation via one or more radiation cavities. Slots are Elongated. The Shape of the Openings Reduces the Amount of Laminar Flow, which May Keep Fluid within the Openings at a More Uniform Temperature. 9. The system of claim 1, wherein the fluid flow slots are elongate with a longer dimension and a shorter dimension. Slot Orientation, e.g., for Zigzag Blocks. The Direction of the Openings May Avoid Blocking Conductive Transfer Through the Bricks Resulting from Absorbing Radiation in the Cavities. 10. The system of claim 8, wherein fluid flow slots of at least one thermal storage block are oriented with their longer dimension in multiple different directions. Upper Blocks Taller. The Upper Part of the Stack is Hotter, so Larger Bricks May Handle the Heat Better. Smaller Bricks at the Bottom May Also Provide More Structural Stability. 11. The system of claim 1, wherein thermal storage blocks are positioned in multiple tiers, wherein the height of radiation cavities and fluid flow slots in a first tier is less than the height of radiation cavities and fluid flow slots in a second tier that is higher than the first tier. Control Heater Elements Based on Vertical Height Optimal Heater Element Energy May Vary Based on Temperature, and the Top of the Stack is Typically Hotter than the Bottom. This May Increase Thermal Retention Efficiency. 12. The system of claim 1, further comprising:control circuitry configured to provide energy to the heater elements;wherein thermal storage blocks are positioned in multiple tiers; andwherein the control circuitry is configured to provide different amounts of energy to the heater elements in at least some of the multiple tiers. Independent vent control for insulated sets of stacks. This may facilitate separate charge/discharge of cells in a TSU. 13. The system of claim 1,wherein the thermal storage assemblage includes:multiple stacks of thermal storage blocks, including a first set of stacks (4107) that is thermally isolated from a second set of stacks (4109); andvents (4111,4113) located under the first set of stacks and the second set of stacks and configured to be independently controlled to direct flow of the stream of fluid into the first set of stacks and the second set of stacks. Cavities are Larger than Slots. Larger Radiation Cavities that would be Needed for Airflow May Facilitate Uniform Radiative Heating. 14. The system of claim 1, wherein the volumes of at least some radiation cavities are greater than neighboring sets of one or more fluid flow slots of a given fluid pathway. Larger Blocks May Reduce Costs of Block Construction and Reduce Friction Damage Between Blocks in a Stack. Certain Shapes May Also Provide Structural Safety, e.g., in Case of Seismic Events. 15. The system of claim 1, wherein at least one of the thermal storage blocks bounds multiple radiation cavities and multiple openings that are at least partially defined by one or more other thermal storage blocks. Tall Blocks. 16. The system of claim 1, wherein a thermal storage block includes radiation cavities and fluid flow slots at multiple vertical elevations. Small Slots Above Heating Elements May Improve Overall Fluid Flow and Even Heat Distribution. 17. The system of claim 1, wherein at least some of the thermal storage blocks include fluid flow slots in a block portion positioned above at least one of the heater elements. Failsafe Vent. 18. The system of claim 1, wherein the thermal storage assemblage includes:an enclosure;wherein the enclosure includes a first vent with a first vent closure, the first vent forming a passage between an interior of the enclosure and an exterior, wherein the apparatus is configured to maintain the first vent closure in a closed position during an operating condition of the fluid movement system; anda failsafe mechanism configured to open the first vent closure in response to a nonoperating condition of the fluid movement system. Dynamic Insulation May Allow Use of Less Expensive Insulation, Improve Equipment Life, or Both. 19. The system of claim 1, wherein the thermal storage assemblage includes:a first enclosure having an interior surface;a second enclosure having an exterior surface, the second enclosure positioned within the first enclosure, wherein the thermal storage blocks are positioned in the second enclosure; anda fluid passage bounded by the exterior surface and the interior surface and in communication with the fluid pathways, wherein the fluid movement system is configured to direct the stream of fluid through the fluid passage and then through the fluid pathways. Interlocking Shelf Portions May Improve Structural Stability and Reduce Friction Damage. 20. The system of claim 1, wherein the thermal storage blocks include shelf portions (3305) that interlock when the thermal storage blocks are positioned in a stack. Cavity and Slot Heights are Substantially the Same. 21. The system of claim 1, wherein the radiation cavities and fluid flow slots at a given vertical elevation have substantially the same height. 22. The system of claim 1, further comprising:an outlet (4303) configured to output gas heated by the thermal storage assemblage. 23. The system of claim 1, wherein the heater elements are connectable to receive energy from one or more energy sources of the following list of energy sources: solar, wind, hydroelectric and geothermal. 24. The system of claim 1, wherein the heater elements are also configured to heat the thermal storage blocks via conduction. 25. The system of claim 1, wherein the fluid includes one or more gases. 26. The system of claim 1, wherein the fluid is air. 27. The system of claim 1, wherein the fluid movement system includes a blower configured to direct the stream of fluid. Failsafe Venting 28. A thermal storage unit (4100), including:a first enclosure;a thermal storage assemblage comprising a plurality of thermal storage blocks within the first enclosure;a plurality of heater elements positioned within the assemblage and configured to heat the plurality of thermal storage blocks;a fluid movement system configured to direct a stream of fluid through fluid pathways in the plurality of thermal storage blocks;wherein the first enclosure defines an interior and an exterior and includes a first vent with a first vent closure, the first vent forming a first passage between the interior and the exterior; anda failsafe mechanism configured to maintain the first vent closure in a closed position during an operating condition of the fluid movement system and to open the first vent closure in response to a nonoperating condition of the fluid movement system. Second Vent is Open to Air Input, Allowing Passive Cooling Using the Chimney Effect, which Draws Cooler Fluid into the Bottom of the Stacks and Prevents Overheating. 29. The thermal storage unit of claim 28, wherein the first enclosure includes a second vent having a second vent closure and forming a second passage between the interior and the exterior, the second passage being configured to allow passage of the fluid to the first passage; andwherein the failsafe mechanism is configured to open the second vent closure in response to the nonoperating condition of the fluid movement system to allow passage of external fluid through the second vent into the interior via the second passage, through the first passage and out of the first enclosure through the first vent. 30. The thermal storage unit of claim 29, wherein the first passage is configured to permit flow of internal heated fluid out of the first enclosure by buoyancy of the internal heated fluid and to permit entry of the external fluid into the first passage as the internal heated fluid flows out of the first enclosure. Rotating Door. 31. The thermal storage unit of claim 29, wherein the first vent closure and the second vent closure are different portions of a vent door, wherein the thermal storage unit is configured to rotate the vent door to close the first and second vents during the operating condition of the fluid movement system. Block Input to Steam Generator. 32. The thermal storage unit of claim 30, further comprising:a steam generator including an input comprising a duct and configured to receive fluid heated by the thermal storage blocks via the duct;wherein the failsafe mechanism is configured to close the duct in response to the nonoperating condition of the fluid movement system. Vent Door Used to Block the Steam Generator Input. 33. The thermal storage unit of claim 32, wherein the first vent closure is positioned to close the duct when the first vent closure is open for the first vent. Open Exterior Input to Steam Generator. 34. The thermal storage unit of claim 32, wherein the second vent forms a passage from the exterior into the input of the steam generator. Failsafe Passively Draws Fluid Through Dynamic Insulation Passage. 35. The thermal storage unit of claim 33, further comprising:a second enclosure having an interior surface, wherein the first enclosure is positioned within the second enclosure;a fluid passage bounded by an exterior surface of the first enclosure and the interior surface and in communication with the fluid pathways;wherein the fluid movement system, during the operating condition, is configured to direct the stream of fluid through the fluid passage before directing the stream of fluid through the fluid pathways;wherein the first vent closure defines a portion of the fluid passage in the closed position; andwherein the open position of the first and second vent closures in the nonoperating condition of the fluid movement system is configured to allow passage of external fluid through the second vent into the interior via the second passage, through the first passage and out of the first enclosure through the first vent. Passive Fluid Movement Through Inactive Blower. 36. The thermal storage unit of claim 35, wherein the open position of the first and second vent closures in the nonoperating condition of the fluid movement system draws fluid from the exterior through the fluid passage via a nonoperating blower of the fluid movement system. Door for Outside Enclosure. 37. The thermal storage unit of claim 35, further comprising a third vent having a third vent closure, wherein the third vent is included in the second enclosure and forms a passage between the interior of the second enclosure and its exterior, wherein the failsafe mechanism is configured to open the third vent closure in response to the nonoperating condition of the fluid movement system. Steam Generator being Positioned Inside Enclosure Helps Keep Leaks Internal, Reducing the Impact of Leaks in the Steam Generator. 38. The thermal storage unit of claim 35, wherein at least a portion of the steam generator that receives heated fluid via the duct is included in the second enclosure. 39. The thermal storage unit of claim 28, wherein the failsafe mechanism is configured to hold the first vent cover in a closed position using electrical power during the operating condition. Clutch/Gravity Implementation of Failsafe Door Opening Mechanism. 40. The thermal storage unit of claim 39, wherein the failsafe mechanism includes a worm drive gear configured to close the first vent cover and an electrical clutch configured to hold the first vent cover in the closed position, wherein the first vent cover is configured to open due to gravitational force when the electrical clutch is not powered. Alternative Implementation of Failsafe Mechanism. 41. The thermal storage unit of claim 39, wherein the failsafe mechanism includes an electrical switch and a motor. Dynamic Insulation—Apparatus 42. A thermal storage unit (4100), including:a first enclosure having an interior surface;a thermal storage assemblage comprising a plurality of thermal storage blocks positioned in a second enclosure having an exterior surface, the second enclosure positioned within the first enclosure, wherein the thermal storage blocks include fluid pathways;a plurality of heater elements positioned within the assemblage and configured to heat the thermal storage blocks; anda fluid passage bounded by the exterior surface and the interior surface and in communication with the fluid pathways; anda fluid movement system configured to direct a stream of fluid through the fluid passage and the fluid pathways. Details on where the Passage Directs Fluid. 43. The thermal storage unit of claim 42, wherein the fluid movement system is configured to direct the stream of fluid upward along a wall of the second enclosure, across a roof of the second enclosure, down along one or more other walls of the second enclosure, then into bottom openings of the fluid pathways of the thermal storage blocks. Bottom Louvers Control Flow into Stacks. 44. The thermal storage unit of claim 42, further comprising:louvers configured to independently control flow of fluid from the fluid passage into different sets of fluid pathways. Failsafe Vents Use Dynamic Insulation Pathway for Failsafe Venting, Improving Safety of the System without Requiring Separate Venting Passages or Powered Mechanisms. 45. The thermal storage unit of claim 42,wherein the second enclosure includes:a first vent with a first vent closure, the first vent forming a first passage between an interior of the first enclosure and an exterior, wherein the thermal storage unit is configured to maintain the first vent closure in a closed position during an operating condition of the fluid movement system; and a second vent having a second vent closure and forming a second passage between the interior and the exterior;wherein the thermal storage unit includes a failsafe mechanism configured to open the first and second vent closures in response to a nonoperating condition of the fluid movement system; andwherein the open position of the first and second vent closures in the nonoperating condition of the fluid movement system are configured to allow passage of external fluid through the second vent into the interior via the second passage, through the first passage, through the fluid pathways and out of the first enclosure through the first vent. 46. The thermal storage unit of claim 45, wherein the first and second vent closures form a portion of the fluid passage when in the closed position. Pressure Differential Between Dynamic Insulation Pathway and Stacks Reduces Impact of Internal Leaks. 47. The thermal storage unit of claim 42, wherein the thermal storage unit is configured to operate in one or more states in which fluid pressure in the fluid passage is greater than fluid pressure within the second enclosure. Source of Fluid for Dynamic Insulation. 48. The thermal storage unit of claim 42, wherein the stream of fluid includes recycled fluid from a steam generator that generates steam using heated fluid from the thermal storage blocks. Methods Including Radiation Cavities, Dynamic Insulation 49. A method, comprising:heating a stack of thermal storage blocks in a thermal storage unit (TSU) that includes a plurality of thermal storage blocks, wherein at least some of the thermal storage blocks include multiple radiation cavities and multiple fluid flow slots, wherein some of the radiation cavities and some of the fluid flow slots are configured to define fluid pathways through the thermal storage blocks;wherein the heating is performed by a plurality of heater elements (3607) positioned within at least some of the thermal storage blocks and adjacent to some of the radiation cavities, via energy radiated into multiple ones of the radiation cavities and onto surfaces that bound the respective radiation cavities within the at least one thermal storage block; anddirecting fluid through the TSU such that a stream of fluid passes through the TSU, including through the fluid pathways. Radiative Transfer in Cavities Improves Heat Distribution Relative to Implementations without Radiation Cavities (e.g., which Might Receive Radiation Along One Wall of a Thermal Storage Brick). 50. The method of claim 49, wherein at least three surfaces of a radiation cavity receive energy radiated from a heater element. 51. The method of claim 50, wherein the fluid flow slots receive radiative energy from the heater element indirectly by reradiation via one or more radiation cavities. Induced Turbulent Flow in Elongated Slots. 52. The method of claim 49, wherein one or more of the plurality of openings are elongated and shaped to introduce turbulent flow of the fluid directed through the one or more of the plurality of openings. 53. An apparatus, comprising:a thermal storage unit (TSU) (4100) including a plurality of thermal storage means, wherein at least some of the thermal storage means include multiple radiation cavities and multiple fluid flow slots, wherein some of the radiation cavities and some of the fluid flow slots are configured to define fluid pathways through the thermal storage means;heater means (3607) positioned within at least some of the thermal storage means and adjacent to some of the radiation cavities, wherein the heater is configured to heat at least one of the thermal storage means via energy radiated into multiple ones of the radiation cavities and onto surfaces that bound the respective radiation cavities within the at least one thermal storage means;fluid movement means (213,4223) for directing a stream of fluid through the TSU, including through the fluid pathways. Radiation Chamber. 54. An apparatus, comprising:one or more thermal storage blocks that define a radiation chamber and a fluid flow slot positioned above the radiation chamber to define a fluid pathway in a first direction;a heater element positioned adjacent to the radiation chamber in a second, different direction, wherein the radiation chamber is open on at least one side to the heater element; anda fluid movement system configured to direct a stream of fluid through the fluid pathway in the first direction. Alternating “Checkerboard” Pattern of Blocks and Radiation Cavities at a Given Tier Facilitates Rapid and Uniform Heat Distribution. 55. A system for thermal energy storage and delivery, including:a plurality of thermal storage blocks positioned to define:a first tier that includes an alternating pattern of block portions, with radiation cavities between neighboring block portions;a second tier that includes an alternating pattern of block portions, with radiation cavities between neighboring block portions, wherein second-tier block portions are positioned adjacent first-tier radiation cavities, and second-tier radiation cavities are positioned adjacent first-tier block portions;fluid flow slots formed in some of the block portions of the thermal storage blocks, the fluid flow slots and radiation cavities positioned to form multiple fluid flow paths through the system;a plurality of heating elements positioned adjacent multiple ones of the radiation cavities in the first and second tiers and configured to heat the plurality of thermal storage blocks via energy radiated into multiple ones of the cavities and onto surfaces that bound the radiation respective cavities within the thermal storage blocks; and a blower configured to direct a stream of fluid through the multiple fluid flow paths. 56. The system of claim 55, wherein the heater elements, the storage blocks and the radiation cavities are configured to provide a substantially vertical thermocline wherein an upper portion of the thermal storage assemblage is at a higher temperature than a lower portion of the thermal storage assemblage. Lead-Lag Process and Deep Discharge to Prevent Thermal Runaway Deep Discharge. 57. A thermal energy storage system (10) configured to produce an output fluid flow (20), the thermal energy storage system comprising:a first assemblage (14A) of first thermal storage blocks (13A) and a second assemblage (14B) of second thermal storage blocks (13B), the first and second thermal storage blocks configured to store thermal energy; anda control system (15) configured to:direct fluid flows during a first discharge period (2067d1) such that the first assemblage, but not the second assemblage, is discharged to within a deep-discharge temperature region (2063r); anddirect fluid flows during a second discharge period (2067d2) such that the second assemblage, but not the first assemblage, is discharged to within the deep-discharge temperature region. 58. The thermal energy storage system of claim 57, wherein the control system is configured, during successive discharge periods (2067d1,2067d2), to alternate between:directing fluid flows to discharge the first assemblage, but not the second assemblage, to within the deep-discharge temperature region; anddirecting fluid flows to discharge the second assemblage, but not the first assemblage, to within the deep-discharge temperature region. 59. The thermal energy storage system of claim 57, wherein the control system is configured to:maintain the output fluid flow at a specified temperature profile (2065b); andin successive discharge periods (2069bd1,2067bd2), alternate between:discharging the first assemblage to within the deep-discharge temperature region while discharging the second assemblage to a current value (2079b) of the specified temperature profile (2065b); anddischarging the second assemblage to within the deep-discharge temperature region while discharging the first assemblage to the current value (2079ba) of the specified temperature profile (2065b); and 60. The thermal energy storage system of claim 57, wherein the control system is configured to:maintain the output fluid flow at a specified temperature profile (2065); andin successive discharge periods (2069cd1,2069cd2), alternate between:discharging the first assemblage to within the deep-discharge temperature region while discharging the second assemblage to a first buffer temperature (2085c) above the specified temperature profile; anddischarging the second assemblage to within the deep-discharge temperature region while discharging the first assemblage to a second buffer temperature (2085ca) above the specified temperature profile. 61. The thermal energy storage system of claim 60, wherein the control system is configured to:maintain the output fluid flow at a specified temperature profile; andin successive discharge periods (2069d,2069da), alternate between:discharging the first assemblage to within the deep-discharge temperature region while 1) discharging the second assemblage to the first buffer temperature (2085d) and 2) maintaining fluid flow to the first assemblage in a trickle mode (2089d); anddischarging the second assemblage to within the deep-discharge temperature region while 1) discharging the first assemblage to the second buffer temperature (2085da) and 2) maintaining fluid flow to the second assemblage in the trickle mode (2089da). 62. The thermal energy storage system of claim 61, wherein, in the trickle mode, fluid flow to a given assemblage being deeply discharged is greater than 0% and less than 10% of a maximum possible flow to the given assemblage. 63. The thermal energy storage system of claim 57, wherein the control system is configured to:use a first set of flow parameters during a first discharge period (2069ed1) to maintain the output fluid flow at a first temperature (2090e) specified by a non-constant temperature profile (2065e);use a second, different set of flow parameters during the first discharge period (2069ed1) to maintain the output fluid flow at a second, different temperature (2091e) specified by the non-constant temperature profile; andmaintain the output fluid flow at second, different temperature during a first charging period (2069ec1) by keeping a first fluid flow for the first assemblage at a relatively constant proportion to a second fluid flow for the second assemblage. 64. The thermal energy storage system of claim 57, further comprising:an inlet valve configured to admit a bypass fluid flow that bypasses the first and second assemblages during discharge periods, the bypass fluid flow having a bypass temperature that is lower than a delivery temperature of the output fluid flow; andwherein the control system is configured to use the bypass fluid flow to produce the output fluid flow during discharge periods. 65. The thermal energy storage system of claim 64, wherein discharging a given one of the first or second assemblages to within the deep-discharge temperature region includes cooling the given assemblage to a discharge temperature approximately equal to the bypass temperature. 66. The thermal energy storage system of claim 64, wherein:an upper end temperature of the deep-discharge temperature region is substantially below a delivery temperature of the output fluid flow; anda lower end temperature of the deep-discharge temperature region is below the upper end temperature and is equal to the bypass temperature. 67. The thermal energy storage system of claim 64, wherein:an upper end temperature of the deep-discharge temperature region is closer to the bypass temperature than to the delivery temperature; anda lower end temperature of the deep-discharge temperature region is below the upper end temperature and is equal to the bypass temperature. 68. The thermal energy storage system of claim 64, wherein:a midpoint temperature is midway between the bypass temperature and the delivery temperature;an upper end temperature of the deep-discharge temperature region is closer to the bypass temperature than to the midpoint temperature; anda lower end temperature of the deep-discharge temperature region is below the upper end temperature and is equal to the bypass temperature. 69. The thermal energy storage system of claim 57, wherein the control system is configured to monitor thermal discharge information for the first and second assemblages in order to determine bounds of the deep-discharge temperature region. 70. The thermal energy storage system of claim 57, wherein the control system is configured to determine bounds of the deep-discharge temperature region based on a computer program that models behavior of the first and second assemblages. 71. The thermal energy storage system of claim 64, wherein the control system is configured to produce the output fluid flow by causing:mixing, during an initial portion of the first discharge period, of a first fluid flow from the first assemblage with the bypass fluid flow;mixing, during a subsequent portion of the first discharge period, of the first fluid flow with a second fluid flow from the second assemblage;mixing, during an initial portion of the second discharge period, of the second fluid with the bypass fluid flow; andmixing, during a subsequent portion of the second discharge period, of the second fluid flow with first fluid flow. 72. The thermal energy storage system of claim 71, wherein the control system is configured to:initiate the subsequent portion of the first discharge period based on a current temperature of the first fluid flow falling below the delivery temperature; andinitiate the subsequent portion of the second discharge period based on a current temperature of the second fluid flow falling below the delivery temperature. 73. The thermal energy storage system of claim 57, wherein the control system is configured to maintain the output fluid flow at a constant temperature, including during the first and second discharge periods. 74. The thermal energy storage system of claim 57, wherein the control system is configured to maintain the output fluid flow according to a specified, non-constant temperature profile. 75. The thermal energy storage system of claim 64, wherein the control system is configured to use the bypass fluid flow to cool the first and second assemblages during a charging period. Alternate Discharging Below Delivery Temperature. 76. A thermal energy storage system configured to produce an output fluid flow, the thermal energy storage system comprising:a first assemblage of first thermal storage blocks and a second assemblage of second thermal storage blocks, the first and second thermal storage blocks configured to store thermal energy; anda control system configured to:direct fluid flows during a first discharge period to perform a first discharge operation in which the first assemblage, but not the second assemblage, is discharged below a delivery temperature of the output fluid flow; anddirect fluid flows during a second, successive discharge period to perform a second discharge operation in which the second assemblage, but not the first assemblage, is discharged below the delivery temperature. 77. The thermal energy storage system of claim 76, wherein the control system is configured to control an inlet valve configured to admit a bypass fluid flow that bypasses the first and second assemblages during discharge periods, the bypass fluid flow having a bypass temperature that is less than the delivery temperature. 78. The thermal energy storage system of claim 77, wherein the control system is configured to:perform the first discharge operation such that the first assemblage is discharged to a first discharge temperature that is closer to the bypass temperature than to the delivery temperature; andperform the second discharge operation such that the second assemblage is discharged to a second discharge temperature that is closer to the bypass temperature than to the delivery temperature. 79. The thermal energy storage system of claim 77, wherein the control system is configured to:perform the first discharge operation such that the first assemblage is discharged to a first discharge temperature that is closer to the bypass temperature than to a midpoint temperature midway between the delivery temperature and the bypass temperature; andperform the second discharge operation such that the second assemblage is discharged to a second discharge temperature that is closer to the bypass temperature than to the midpoint temperature. 80. The thermal energy storage system of claim 77, wherein the control system is configured to:perform the first discharge period such that the first assemblage is discharged to a first discharge temperature that is approximately equal to the bypass temperature; andperform the second discharge period such that the second assemblage is discharged to a second discharge temperature that is approximately equal to the bypass temperature. 81. The thermal energy storage system of claim 78, wherein the control system is configured to cause the first and second discharge operations to be performed alternately in successive discharge periods. 82. The thermal energy storage system of claim 78, wherein the thermal energy storage system is configured to produce the output fluid flow according to a non-constant temperature profile. 83. The thermal energy storage system of claim 78, wherein the control system is configured to:perform the first discharge operation by discharging the first assemblage below the delivery temperature, and then initiating fluid flow to the first assemblage in a trickle mode; andperform the second discharge operation by discharging the second assemblage below the delivery temperature, and then initiating fluid flow to the second assemblage in the trickle mode. Preventing Thermal Runaway by Discharge Operation. 84. A thermal energy storage system, comprising:a first assemblage of first thermal storage blocks and a second assemblage of second thermal storage blocks, the first and second thermal storage blocks configured to store thermal energy; anda control system configured to:direct fluid flows to the first and second assemblages to produce an output fluid flow;during a first discharge period, perform a first discharge operation by discharging the first assemblage sufficiently to prevent thermal runaway while discharging the second assemblage to at or above a delivery temperature of the output fluid flow; andduring a second, successive discharge period, perform a second discharge operation by discharging the second assemblage sufficiently to prevent thermal runaway while discharging the first assemblage to at or above the delivery temperature. 85. The thermal energy storage system of claim 84, wherein the control system is configured to:perform the first discharge operation by initiating discharge of the first assemblage at a beginning of the first discharge period and initiating discharge of the second assemblage after a first discharge temperature of a first fluid flow produced by the first assemblage drops below the delivery temperature; andperform the second discharge operation by initiating discharge of the second assemblage at a beginning of the second discharge period and initiating discharge of the first assemblage after a second discharge temperature of a second fluid flow produced by the second assemblage drops below the delivery temperature. 86. The thermal energy storage system of claim 85, wherein the control system is configured to cause the first and second discharge operations to be performed alternately in successive discharge periods. 87. The thermal energy storage system of claim 85, wherein the control system is configured to perform the first and second discharge operations by initiating a fluid flow to a given assemblage in a trickle mode after discharging the given assemblage to prevent thermal runaway. Deep Discharge with Bypass Fluid Flow During First and Second Discharge Periods. 88. A thermal energy storage system configured to produce an output fluid flow, the thermal energy storage system comprising:a first assemblage of first thermal storage blocks and a second assemblage of second thermal storage blocks, the first and second thermal storage blocks configured to store thermal energy; anda control system configured to:cause, during a first portion of a first discharge period, a first fluid flow produced from the first assemblage to be mixed with a bypass fluid flow that bypasses the first and second assemblages;cause, during a second, subsequent portion of the first discharge period, the first fluid flow to be mixed with a second fluid flow produced from the second assemblage, such that the first assemblage, but not the second assemblage, is deeply discharged during the first discharge period;cause, during a first portion of a second discharge period, the second fluid flow to be mixed with the bypass fluid flow; andcause, during a second, subsequent portion of the second discharge period, the second fluid flow to be mixed with the first fluid flow such that the second assemblage, but not the first assemblage, is deeply discharged during the second discharge period. 89. The thermal energy storage system of claim 88, wherein the control system is configured to alternate, in successive discharge periods, between:deeply discharging the first assemblage but not the second assemblage; anddeeply discharging the second assemblage but not the first assemblage. 90. The thermal energy storage system of claim 89, wherein the control system is configured to initiate a fluid flow to a given one of the first and second assemblage in a trickle mode after deeply discharging the given assemblage. Method of Deep Discharge. 91. A method, comprising:receiving, by a thermal energy storage system that includes a first assemblage of first thermal storage blocks and a second assemblage of second thermal storage blocks, input energy from a renewable energy source;using, by the thermal energy storage system, the input energy to create thermal energy that is stored in the first and second thermal storage blocks;directing, by the thermal energy storage system, fluid flows to create an output fluid flow that is continuous over one or more periods of unavailability of the renewable energy source by: performing, in a first discharge period, a first discharge operation that deeply discharges the first assemblage, but not the second assemblage; andperforming, in a second discharge period, a second discharge operation that deeply discharges the second assemblage, but not the first assemblage. 92. The method of claim 91, wherein the fluid flows include a first flow produced from the first assemblage, a second flow produced from the second assemblage, and a bypass flow produced that bypasses the first and second assemblages during discharge periods, the bypass flow having a bypass temperature that is lower than a delivery temperature of the output fluid flow. 93. The method of claim 92, wherein deeply discharging a given one of the first and second assemblages includes discharging to a discharge temperature that is closer to the bypass temperature than the delivery temperature. 94. The method of claim 92, wherein deeply discharging a given one of the first and second assemblages includes discharging to a discharge temperature that is closer to the bypass temperature than to a midpoint temperature midway between the delivery temperature and the bypass temperature. 95. The method of claim 92, wherein deeply discharging a given one of the first and second assemblages includes discharging to a discharge temperature that is approximately equal to the bypass temperature. 96. The method of claim 92, wherein deeply discharging a given one of the first and second assemblages during a given discharge period includes:initiating discharge of the given assemblage at a beginning of the given discharge period; andinitiating discharge of the other one of the first and second assemblages after a discharge temperature of a given fluid flow produced by the given assemblage drops below the delivery temperature; andcontinuing discharge of the given assemblage after initiating discharge of the other assemblage. 97. The method of claim 92, wherein deeply discharging a given one of the first and second assemblages constitutes discharging the given assemblage to a discharge temperature that is no higher than 25° C. above than the bypass temperature. 98. The method of claim 92, wherein deeply discharging a given one of the first and second assemblages constitutes discharging the given assemblage to a discharge temperature that is no higher than 50° C. above the bypass temperature. 99. The method of claim 92, wherein deeply discharging a given one of the first and second assemblages constitutes discharging the given assemblage to a discharge temperature that is no higher than 75° C. above than the bypass temperature. 100. The method of claim 92, wherein deeply discharging a given one of the first and second assemblages constitutes discharging the given assemblage to a discharge temperature that is no higher than 100° C. above than the bypass temperature. 101. The method of claim 92, wherein deeply discharging a given one of the first and second assemblages constitutes discharging the given assemblage to a discharge temperature that is no higher than 150° C. above than the bypass temperature. 102. The method of claim 92, wherein deeply discharging a given one of the first and second assemblages constitutes discharging the given assemblage to a discharge temperature that is no higher than 200° C. above than the bypass temperature. 103. The method of claim 93, wherein performing the first discharge operation includes discharging the second assemblage to the delivery temperature, and wherein performing the second discharge operation includes discharging the first assemblage to the delivery temperature. 104. The method of claim 93, wherein performing the first discharge operation includes discharging the second assemblage to a first buffer temperature above the delivery temperature, and wherein performing the second discharge operation includes discharging the first assemblage to a second buffer temperature that is above the delivery temperature. 105. The method of claim 93, wherein performing the first discharge operation includes initiating fluid flow to the first assemblage in a trickle mode after deeply discharging the first assemblage, and wherein performing the second discharge operation includes initiating fluid flow to the second assemblage in the trickle mode after deeply discharging the second assemblage. 106. The method of claim 105, wherein fluid flow in the trickle mode for a given assemblage is greater than 0% and no more than 10% of a maximum fluid flow for the given assemblage. 107. The method of claim 92, further comprising changing flow rates for the first flow, the second flow, and the bypass flow to account for a change in the delivery temperature. 108. The method of claim 92, further comprising using the bypass flow to cool the first and second assemblages at a latter portion of a charging period. 109. The method of claim 93, further comprising:alternating, in successive discharge periods, between performing the first discharge operation and the second discharge operation. Method with Discharge Temperature Closer to Bypass Temperature than to Delivery Temperature. 110. A method, comprising:receiving, by a thermal energy storage system that includes a first assemblage of first thermal storage blocks and a second assemblage of second thermal storage blocks, input energy from a renewable energy source;using, by the thermal energy storage system, the input energy to create thermal energy that is stored in the first and second thermal storage blocks;directing, by the thermal energy storage system, fluid flows to create an output fluid flow, the fluid flows including a first fluid flow produced from the first assemblage, a second fluid flow produced from the second assemblage, and a bypass fluid flow that bypasses the first and second assemblages during discharge periods, the bypass fluid flow having a bypass temperature that is lower than a delivery temperature of the output fluid flow;discharging, during a first discharge period, the first assemblage, but not the second assemblage, to a first discharge temperature that is closer to the bypass temperature than to the delivery temperature; anddischarging, during a second discharge period, the second assemblage, but not the first assemblage, to a second discharge temperature that is closer to the bypass temperature than the delivery temperature. 111. The method of claim 110, wherein the first and second discharge temperatures are closer to the bypass temperature than to a temperature midpoint that is midway between the bypass temperature and the delivery temperature. 112. The method of claim 110, wherein the first and second discharge temperatures are approximately equal to the bypass temperature. 113. The method of claim 110, wherein discharging the first assemblage during the first discharge period includes initiating fluid flow to the first assemblage in a trickle mode after discharging the first assemblage to the first discharge temperature; andwherein discharging the second assemblage during the second discharge period includes initiating fluid flow to the second assemblage in the trickle mode after discharging the second assemblage to the second discharge temperature. Method with Discharge to Reduce Thermal Runaway. 114. A method, comprising:receiving, by a thermal energy storage system that includes a first assemblage of first thermal storage blocks and a second assemblage of second thermal storage blocks, input energy from a renewable energy source;using, by the thermal energy storage system, the input energy to create thermal energy that is stored in the first and second thermal storage blocks;controlling fluid flows to the first and second assemblages to produce an output fluid flow at temperatures within a selected temperature range, wherein the controlling causes:during a first discharge period, discharging the first assemblage in a manner sufficient to reduce thermal runaway in the first thermal storage blocks while discharging the second assemblage to a temperature at or above the selected temperature range; andduring a second, successive discharge period, discharging the second assemblage in a manner sufficient to reduce thermal runaway in the second thermal storage blocks while discharging the first assemblage to a temperature at or above the selected temperature range. 115. The method of claim 114, wherein discharging the first assemblage during the first discharge period includes initiating fluid flow to the first assemblage in a trickle mode after deeply discharging the first assemblage, and wherein discharging the second assemblage during the second discharge period includes initiating fluid flow to the second assemblage in the trickle mode after deeply discharging the second assemblage. 116. The method of claim 114, wherein discharging the first and second assemblages to reduce thermal runaway is performed based on measured thermal data for the first and second assemblages. 117. The method of claim 114, wherein discharging the first and second assemblages to reduce thermal runaway is performed based on a modeling of thermal data for the first and second assemblages. System with a Given Stack Discharge Temperature Closer to Bypass Temperature than to Delivery Temperature and Lower than Other Stack's Discharge Temperature. 118. A thermal energy storage system configured to produce an output fluid flow having a delivery temperature, the thermal energy storage system comprising:a first assemblage of first thermal storage blocks and a second assemblage of second thermal storage blocks, the first and second thermal storage blocks configured to store thermal energy; andan inlet valve;a control system configured to:cause the inlet valve to admit a bypass fluid flow that bypasses the first and second assemblages, the bypass fluid flow having a bypass temperature that is lower than the delivery temperature;during a first discharge period, perform a first discharge operation in which the first assemblage is discharged to a first discharge temperature that is (a) closer to the bypass temperature than to the delivery temperature, and (b) lower than a second discharge temperature of the second assemblage; andduring a second, successive discharge period, perform a second discharge operation in which the second assemblage is discharged to a third discharge temperature that is (a) closer to the bypass temperature than to the delivery temperature and (b) lower than a fourth discharge temperature of the first assemblage. 119. The thermal energy storage system of claim 118, wherein the control system is configured to alternate between performing the first discharge operation and the second discharge operation in successive discharge periods. 120. The thermal energy storage system of claim 119, wherein the second and fourth discharge temperatures of the first and second discharge periods, respectively, correspond to the delivery temperature. 121. The thermal energy storage system of claim 119, wherein the second discharge temperature corresponds to a first buffer temperature above the specified delivery temperature, and wherein the fourth discharge temperature corresponds to a second buffer temperature above the specified delivery temperature. 122. The thermal energy storage system of claim 121, wherein:the first discharge operation further includes maintaining a first trickle fluid flow to the first assemblage after discharging the first assemblage to the first discharge temperature; andthe second discharge operation further includes maintaining a second trickle fluid flow to the second assemblage after discharging the second assemblage to the second discharge temperature. 123. The thermal energy storage system of claim 122, wherein:the first trickle fluid flow is less than 10% of a maximum fluid flow for the first assemblage; andthe second trickle fluid flow is less than 10% of a maximum fluid flow for the second assemblage. 124. The thermal energy storage system of claim 118, wherein the first discharge temperature and the second discharge temperature are closer to the bypass temperature than to a temperature midpoint that is midway between the bypass temperature and the delivery temperature. System with Deep Discharge to Reduce Temperature Nonuniformities. 125. A thermal energy storage system, comprising:one or more assemblages of thermal storage blocks, wherein each assemblage is configured to store heat generated from received electrical energy as thermal energy; anda control system configured to:direct fluid flows to the one or more assemblages to produce an output fluid flow, andcause each of the one or more assemblages to be periodically deeply discharged to reduce temperature nonuniformities within the one or more assemblages. 126. The thermal energy storage system of claim 125, wherein the one or more assemblages is made up of a single assemblage, and wherein the control system is configured to cause the single assemblage to periodically be deeply discharged on an as-needed basis. 127. The thermal energy storage system of claim 125, wherein the one or more assemblages is made up of a single assemblage, and wherein the control system is configured to cause the single assemblage to periodically be deeply discharged at regularly occurring intervals. 128. The thermal energy storage system of claim 125, wherein the one or more assemblages are a plurality of N assemblages, and wherein the control system is configured to cause each of the N assemblages to be deeply discharged once every N discharge periods. 129. The thermal energy storage system of claim 125, wherein the output fluid flow has a specified temperature profile, wherein the one or more assemblages are a plurality of N assemblages, and wherein the control system is configured to cause each of the N assemblages to be deeply discharged at least once every N discharge periods and partially discharged to a current value of the specified temperature profile at least once every N discharge periods. 130. The thermal energy storage system of claim 125, wherein the one or more assemblages includes a first assemblage and a second assemblage, and wherein the control system is configured to alternate, in successive discharge periods, between:deeply discharging the first assemblage and partially discharging the second assemblage to a current value of the specified temperature profile; anddeeply discharging the second assemblage and partially discharging the first assemblage to the current value of the specified temperature profile. 131. The thermal energy storage system of claim 125, wherein the control system is configured to open an inlet valve to admit a bypass fluid flow that is mixed with other fluid flows to produce the output fluid flow, the output fluid flow having a delivery temperature and the bypass fluid flow having a bypass temperature, and wherein the one or more assemblages are deeply discharged to be closer to the bypass temperature than to the delivery temperature. 132. The thermal energy storage system of claim 125, wherein the control system is configured to provide supply a trickle fluid flow to a given assemblage after the given assemblage has been deeply discharged. Method with Deep Discharge to Reduce Temperature Nonuniformities. 133. A method, comprising:receiving, at a thermal storage structure, input electrical energy from a renewable energy source;using, by thermal storage structure, the received input electrical energy to heat heating elements within one or more assemblages of thermal storage blocks;directing fluid flows to the one or more assemblages to produce an output fluid flow having a delivery temperature; anddeeply discharging each of the one or more assemblages periodically to reduce temperature nonuniformities. 134. The method of claim 133, wherein the one or more assemblages comprise a plurality of N assemblages, and wherein each of the N assemblages is deeply discharged once every N discharge periods. 135. The method of claim 134, wherein each of the N assemblages is deeply discharged at least once every N discharge periods and partially discharged at least once every N discharge periods. 136. The method of claim 133, wherein the one or more assemblages include a first assemblage and a second assemblage, and wherein the method further comprises alternating, in successive discharge periods, between:deeply discharging the first assemblage and partially discharging the second assemblage; anddeeply discharging the second assemblage and partially discharging the first assemblage. 137. The method of claim 136, wherein the partially discharging constitutes discharging to the delivery temperature of the output fluid flow. 138. The method of claim 133, wherein the fluid flows include flows from each of the one or more assemblages and a bypass fluid flow from an inlet valve that bypasses the one or more assemblages during discharge periods, the bypass fluid flow having a bypass temperature that is lower than the delivery temperature. 139. The method of claim 138, wherein the one or more assemblages are deeply discharged to discharge temperatures that are closer to the bypass temperature than to the delivery temperature. 140. The method of claim 138, wherein the one or more assemblages are deeply discharged to discharge temperatures that are closer to the bypass temperature than to a temperature midpoint that is midway between the bypass temperature and the delivery temperature. 141. The method of claim 136, further comprising causing a trickle fluid flow to be provided to a given assemblage during a discharge period after the given assemblage has been deeply discharged. 142. The method of claim 138, wherein deeply discharging a given assemblage constitutes discharging to temperatures that are no higher than 25° C. above than the bypass temperature. 143. The method of claim 138, wherein deeply discharging a given assemblage constitutes discharging to temperatures that are no higher than 50° C. above than the bypass temperature. 144. The method of claim 138, wherein deeply discharging a given assemblage constitutes discharging to temperatures that are no higher than 75° C. above than the bypass temperature. 145. The method of claim 138, wherein deeply discharging a given assemblage constitutes discharging to temperatures that are no higher than 100° C. above than the bypass temperature. 146. The method of claim 138, wherein deeply discharging a given assemblage constitutes discharging to temperatures that are no higher than 150° C. above than the bypass temperature. 147. The method of claim 138, wherein deeply discharging a given assemblage constitutes discharging to temperatures that are no higher than 200° C. above than the bypass temperature. Thermal Energy Storage System Including Steam Generator with Feedback Control. The System Allows Control of the Temperature and Flow Rate of Heated Fluid, and Hence the Amount of Heat Delivered to the Steam Generator, Allowing the Steam Quality to be Precisely Controlled Using Feedback. 148. A thermal energy storage system, comprising:a storage medium (14,209) configured to store thermal energy obtained using an input energy supply from an energy source (2,201);a fluid movement device (213,4223) configured to move fluid through the storage medium and discharge the stored thermal energy from the storage medium into the fluid;a once-through steam generator (1419) configured to receive the fluid (20) from the storage medium and to exchange heat from the fluid with water from a water source to produce steam; anda control system (15,1502) configured tomeasure a value indicating steam quality of the steam; andbased on the measured value, control a flow rate of the fluid received by the steam generator. 149. The thermal energy storage system of claim 148, further comprising one or more instruments configured to detect the value indicating steam quality of the steam, and wherein the control system is configured to measure the value by interfacing with the instruments. 150. The thermal energy storage system of claim 148, wherein the one or more instruments are configured to detect an inlet flow velocity of water at an inlet of the steam generator and an outlet flow velocity of steam at an outlet of the steam generator. 151. The thermal energy storage system of claim 149, further comprising a vapor-liquid separator configured to separate the steam into a liquid component and a vapor component, and wherein the one or more instruments are configured to detect a liquid component heat value and a vapor component heat value. 152. The thermal energy storage system of claim 148, wherein the control system is configured to measure an inlet flow velocity of water at an inlet of the steam generator and an outlet flow velocity of steam at an outlet of the steam generator. 153. The thermal energy storage system of claim 148, further comprising a vapor-liquid separator configured to separate the steam into a liquid component and a vapor component, and wherein the control system is configured to measure a liquid component heat value and a vapor component heat value. 154. The thermal energy storage system of claim 148, further comprising an adjustable fluid restricting device, and wherein the control system is configured to send control signals to the adjustable fluid restricting device based on the measured value. 155. The thermal energy storage system of claim 154, wherein the adjustable fluid restricting device comprises a louver. 156. The thermal energy storage system of claim 154, wherein the adjustable fluid restricting device comprises a valve. 157. The thermal energy storage system of claim 148, wherein, if the measured value of steam quality indicates a decrease in steam quality, the control system is configured to increase a flow rate of the fluid. The Control of Flow Rate and Temperature Provided by the Thermal Energy Storage System Allows Control of Output Steam Parameters Using Flow Rate. 158. The thermal energy storage system of claim 148, wherein the control system is configured to:prior to measuring the value indicating steam quality, receive a target steam parameter;obtain an inlet water temperature at an inlet of the steam generator; andbased on the target steam parameter and the inlet temperature, determine an initial flow rate for the fluid received by the steam generator. 159. The thermal energy storage system of claim 158, wherein the target steam parameter comprises a target steam quality. 160. The thermal energy storage system of claim 158, wherein the target steam parameter comprises a target steam delivery rate. 161. The thermal energy storage system of claim 158, wherein the controller is configured to obtain the inlet water temperature by measuring the inlet water temperature. 162. The thermal energy storage system of claim 148, wherein the steam generator comprises a once-through steam generator. 163. The thermal energy storage system of claim 148, wherein the energy source is a source of intermittent availability. 164. The thermal energy storage system of claim 148, wherein the energy source comprises a solar energy source. 165. The thermal energy storage system of claim 148, wherein the energy source comprises a wind-powered energy source. Thermal Energy Storage System Method of Operation Controls the Temperature and Flow Rate of Heated Fluid, and Therefore the Amount of Heat Delivered to the Steam Generator, Allowing the Steam Quality to be Precisely Controlled Using Feedback. 166. A method of storing and delivering thermal energy, comprising:receiving input energy from an energy source (2,201);storing thermal energy obtained using the input energy in a storage medium (14,209);moving fluid through the storage medium to heat the fluid;delivering the heated fluid (20) to a once-through steam generator (1419) configured to generate steam by exchanging heat from the fluid with water from a water source;obtaining a steam quality value of the steam; andbased on the steam quality value, providing a feedback signal for adjusting a rate of delivering the heated fluid to the steam generator. 167. The method of claim 166, wherein obtaining the steam quality value comprises:separating the steam into liquid phase and vapor phase components; andindependently monitoring heat of the liquid phase and vapor phase components. 168. The method of claim 166, wherein obtaining the steam quality value comprises:measuring an outlet flow velocity of the steam at an outlet of the steam generator; andmeasuring an inlet flow velocity of the water at an inlet of the steam generator. 169. The method of claim 166, wherein providing a feedback signal comprises providing the signal to a controllable element is configured to adjust a flow rate of the fluid through the storage medium. 170. The method of claim 169, wherein the controllable element comprises a louver. 171. The method of claim 169, wherein the controllable element comprises a valve. Control of Flow Rate and Temperature Provides Control of Output Steam Parameters on a Feed-Forward Basis. 172. The method of claim 166, further comprising, prior to obtaining the steam quality value of the steam:receiving a target parameter for the steam;obtaining an inlet water temperature at an inlet of the steam generator; andbased on the target steam parameter and the inlet temperature, determining an initial rate for delivering the heated fluid to the steam generator. 173. The method of claim 172, wherein receiving a target parameter comprises receiving a target steam quality. 174. The method of claim 172, wherein receiving a target parameter comprises receiving a target steam delivery rate. 175. The method of claim 172, wherein obtaining an inlet water temperature comprises measuring the inlet water temperature. Control of Steam Quality Using Flow Rate from Thermal Storage. 176. The method of claim 166, wherein the steam generator comprises a once-through steam generator. 177. The method of claim 166, wherein the energy source is a source of intermittent availability. 178. The method of claim 166, wherein the energy source comprises a solar energy source. 179. The method of claim 166, wherein the energy source comprises a wind-powered energy source. System Configured to Control Flow Rate and Temperature to Control Output Steam Parameters on a Feed-Forward Basis. 180. A thermal energy storage system, comprising:a storage medium (14,209) configured to store thermal energy obtained using an input energy supply from an energy source (2,201);a fluid movement device (213,4223) configured to move fluid through the storage medium and discharge the stored thermal energy from the storage medium into the fluid;a steam generator (1419) configured to receive the fluid (20) from the storage medium and to exchange heat from the fluid with water from a water source to produce steam; anda control system (15,1502) configured toreceive a target steam parameter,obtain an inlet water temperature at an inlet of the steam generator; andbased on the target steam parameter and the inlet temperature, determine an initial flow rate for the fluid received by the steam generator. 181. The thermal energy storage system of claim 180, wherein the target steam parameter comprises a target steam quality. 182. The thermal energy storage system of claim 180, wherein the target steam parameter comprises a target steam delivery rate. 183. The thermal energy storage system of claim 180, wherein the controller is configured to obtain the inlet water temperature by measuring the inlet water temperature. System Configured Control Temperature and Flow Rate of Heated Fluid, and Therefore the Amount of Heat Delivered to the Steam Generator, Allowing the Steam Quality to be Precisely Controlled Using Feedback. 184. The thermal energy storage system of claim 180, wherein the control system is configured to:measure a value indicating steam quality of the steam; andbased on the measured value, control an ongoing flow rate of the fluid received by the steam generator. 185. The thermal energy storage system of claim 184, further comprising one or more instruments configured to detect the value indicating steam quality of the steam, and wherein the control system is configured to measure the value by interfacing with the instruments. 186. The thermal energy storage system of claim 185, wherein the one or more instruments are configured to detect an inlet flow velocity of water at an inlet of the steam generator and an outlet flow velocity of steam at an outlet of the steam generator. 187. The thermal energy storage system of claim 185, further comprising a vapor-liquid separator configured to separate the steam into a liquid component and a vapor component, and wherein the control system is configured to measure a liquid component heat value and a vapor component heat value. 188. The thermal energy storage system of claim 184, further comprising an adjustable fluid restricting device, and wherein the control system is configured to send a control signal to the adjustable fluid restricting device based on the measured value. 189. The thermal energy storage system of claim 188, wherein the adjustable fluid restricting device comprises a louver. 190. The thermal energy storage system of claim 188, wherein the adjustable fluid restricting device comprises a valve. 191. The thermal energy storage system of claim 180, wherein the steam generator comprises a once-through steam generator. 192. The thermal energy storage system of claim 180, wherein the energy source is a source of intermittent availability. 193. The thermal energy storage system of claim 180, wherein the energy source comprises a solar energy source. 194. The thermal energy storage system of claim 180, wherein the energy source comprises a wind-powered energy source. 195. A method of storing and delivering thermal energy, comprising:receiving input energy from an energy source (2,201);storing thermal energy obtained using the input energy in a storage medium (14,209);moving fluid through the storage medium to heat the fluid;delivering the heated fluid (20) to steam generator (1419) configured to generate steam by exchanging heat from the fluid with water from a water source;receiving a target parameter for the steam;obtaining an inlet water temperature at an inlet of the steam generator; andbased on the target steam parameter and the inlet temperature, determining an initial rate for delivering the heated fluid to the steam generator. 196. The method of claim 195, wherein receiving a target parameter comprises receiving a target steam quality. 197. The method of claim 195, wherein receiving a target parameter comprises receiving a target steam delivery rate. 198. The method of claim 195, wherein obtaining the inlet water temperature comprises measuring the inlet water temperature. 199. The method of claim 195, further comprising, subsequent to determining the initial rate:obtaining a steam quality value of the steam; andbased on the steam quality value, providing a feedback signal for adjusting an ongoing rate of delivering the heated fluid to the steam generator. 200. The method of claim 199, wherein obtaining a steam quality value comprises:separating the steam into liquid phase and vapor phase components; andindependently monitoring heat of the liquid phase and vapor phase components. 201. The method of claim 199, wherein obtaining a steam quality value comprises:measuring an outlet flow velocity of the steam at an outlet of the steam generator; andmeasuring an inlet flow velocity of the water at an inlet of the steam generator. 202. The method of claim 199, wherein providing a feedback signal comprises providing the signal to a controllable element configured to adjust a flow rate of the fluid through the storage medium. 203. The method of claim 202, wherein the controllable element comprises a louver. 204. The method of claim 202, wherein the controllable element comprises a valve. 205. The method of claim 195, wherein the steam generator comprises a once-through steam generator. 206. The method of claim 195, wherein the energy source is a source of intermittent availability. 207. The method of claim 195, wherein the energy source comprises a solar energy source. 208. The method of claim 195, wherein the energy source comprises a wind-powered energy source. System Combining the Outputs of Two Thermal Storage Mediums while Separately Controlling Flow Through them Allows a Specified Output Property of the Delivered Fluid to be Maintained. 209. A thermal energy storage system, comprising:a first storage medium (14,209) configured to store thermal energy obtained using an input energy supply from an energy source (2,201);a second storage medium (14,209) configured to store thermal energy obtained using the input energy supply;a fluid movement device (213,4223) configured to move fluid through the first and second storage mediums to heat the fluid and provide the heated fluid (20) to a load system (22); anda control system (15,1502) configured to separately control movement of the fluid through the first and second storage mediums to maintain a specified property of the heated fluid. 210. The thermal energy storage system of claim 209, wherein the specified property comprises a temperature of the heated fluid. 211. The thermal energy storage system of claim 209, wherein the specified property comprises a thermal energy of the heated fluid. 212. The thermal energy storage system of claim 209, wherein the specified property comprises a flow rate of the heated fluid. 213. The thermal energy storage system of claim 209, further comprising:a first adjustable fluid restricting device configured to adjust a rate of fluid flow through the first storage medium; anda second adjustable fluid restricting device configured to adjust a rate of fluid flow through the second storage medium. 214. The thermal energy storage system of claim 213, wherein the control system is configured to separately send control signals to the first and second adjustable fluid restricting devices. 215. The thermal energy storage system of claim 213, wherein the first and second adjustable fluid restricting devices comprise louvers. 216. The thermal energy storage system of claim 213, wherein the first and second adjustable fluid restricting devices comprise valves. 217. The thermal energy storage system of claim 209, wherein the load system comprises a steam generator. 218. The thermal energy storage system of claim 217, wherein the steam generator comprises a once-through steam generator. 219. The thermal energy storage system of claim 209, wherein the load system comprises an electrolysis reactor. 220. The thermal energy storage system of claim 209, wherein the load system comprises a material activation system. 221. The thermal energy storage system of claim 220, wherein the material activation system comprises a calciner. 222. The thermal energy storage system of claim 209, wherein the energy source is a source of intermittent availability. 223. The thermal energy storage system of claim 209, wherein the energy source comprises a solar energy source. 224. The thermal energy storage system of claim 209, wherein the energy source comprises a wind-powered energy source. Method Combining the Outputs of Two Thermal Storage Mediums while Separately Controlling Flow Through them Allows a Specified Output Property of the Delivered Fluid to be Maintained. 225. A method of storing and delivering thermal energy, comprisingreceiving input energy from an energy source (2,201);storing thermal energy obtained using the input energy in a first storage medium (14,209) and a second storage medium (14,209);moving fluid through the first and second storage mediums to heat the fluid;delivering the heated fluid (20) to a load system (22); andseparately controlling flow rates of the fluid through the first and second storage mediums to maintain a specified property of the heated fluid. 226. The method of claim 225, wherein the specified property comprises a temperature of the heated fluid. 227. The method of claim 225, wherein the specified property comprises a thermal energy of the heated fluid. 228. The method of claim 225, wherein the specified property comprises a flow rate of the heated fluid. 229. The method of claim 225, wherein separately controlling flow rates of the fluid through the first and second storage mediums comprises sending separate control signals to first and second adjustable fluid restricting devices associated with the first and second storage mediums, respectively. 230. The method of claim 229, wherein the first and second adjustable fluid restricting devices comprise louvers. 231. The method of claim 229, wherein the first and second adjustable fluid restricting devices comprise valves. 232. The method of claim 225, wherein the load system comprises a steam generator. 233. The method of claim 232, wherein the steam generator comprises a once-through steam generator. 234. The method of claim 225, wherein the load system comprises an electrolysis system. 235. The method of claim 234, wherein the load system comprises a material activation system. 236. The method of claim 235, wherein the material activation system comprises a calciner. 237. The method of claim 225, wherein the energy source is a source of intermittent availability. 238. The method of claim 225, wherein the energy source comprises a solar energy source. 239. The method of claim 225, wherein the energy source comprises a wind-powered energy source. Use of Forecast Information Regarding Energy Source Availability Allows the System to Adjust its Received Energy, Helping to Maintain Consistent Operation. 240. A thermal energy storage system, comprising:a storage medium (14,209) configured to store thermal energy obtained using input energy from an energy source (2,201);a fluid movement device (213,4223) configured to move fluid through the storage medium to heat the fluid and provide the heated fluid (20) to a load system (22); anda control system (15,1502) configured to:receive forecast information regarding availability of the energy source; andbased on the forecast information, control a heated fluid discharge rate. 241. The thermal energy storage system of claim 240, wherein the control system is configured to communicate with an energy source control system. 242. The thermal energy storage system of claim 241, wherein the control system is configured to send to the energy source control system a request or instruction to reduce an amount of input energy supplied by the source when the forecast information indicates an increase in availability of the energy source. 243. The thermal energy storage system of claim 241, wherein the control system is configured to send to the energy source control system a request or instruction to transfer excess energy to an available power grid when the forecast information indicates an increase in availability of the energy source. 244. The thermal energy storage system of claim 241, wherein the control system is configured to send to the energy source control system a request or instruction to curtail a portion of the energy source's production when the forecast information indicates an increase in availability of the energy source. 245. The thermal energy storage system of claim 240, wherein the control system is configured to connect to an available power grid to obtain additional input energy when the forecast information indicates a decrease in availability of the energy source. 246. The thermal energy storage system of claim 240, wherein the control system is configured to connect to an alternate energy source when the forecast information indicates a decrease in availability of the energy source. 247. The thermal energy storage system of claim 240, wherein the control system is configured to receive the forecast information from an energy source control system. 248. The thermal energy storage system of claim 240, wherein the control system is configured to receive the forecast information from an analytics system external to the control system. 249. The thermal energy storage system of claim 240, wherein the energy source is a source of intermittent availability. 250. The thermal energy storage system of claim 240, wherein the energy source comprises a solar energy source. 251. The thermal energy storage system of claim 240, wherein the energy source comprises a wind-powered energy source. Use of Forecast Information Regarding Energy Source Availability Allows the System to Adjust its Received Energy, Helping to Maintain Consistent Operation. 252. A method of storing and delivering thermal energy, comprising:receiving input energy from an energy source (2,201);storing in a storage medium (14,209) thermal energy obtained using the input energy;moving fluid through the storage medium to heat the fluid for delivery to a load system (22);receiving forecast information regarding availability of the energy source; andbased on the forecast information, controlling a heated fluid discharge rate. 253. The method of claim 252, wherein altering the amount of input energy comprises communicating with a control system for the energy source. 254. The method of claim 253, wherein communicating with the control system for the energy source comprises sending a request or instruction to reduce an amount of input energy supplied by the source when the forecast information indicates an increase in availability of the energy source. 255. The method of claim 253, wherein communicating with the control system for the energy source comprises sending a request or instruction to transfer excess energy to an available power grid when the forecast information indicates an increase in availability of the energy source. 256. The method of claim 253, wherein communicating with the control system for the energy source comprises sending a request or instruction to curtail a portion of the energy source's production when the forecast information indicates an increase in availability of the energy source. 257. The method of claim 252, wherein altering the amount of input energy comprises connecting to an available power grid to obtain additional input energy when the forecast information indicates a decrease in availability of the energy source. 258. The method of claim 252, wherein altering the amount of input energy comprises connecting to an alternate energy source when the forecast information indicates a decrease in availability of the energy source. 259. The method of claim 252, wherein receiving forecast information comprises receiving information from a control system of the energy source. 260. The method of claim 252, wherein receiving forecast information comprises receiving information from an analytics system. 261. The method of claim 250, wherein the energy source is a source of intermittent availability. 262. The method of claim 252, wherein the energy source comprises a solar energy source and/or a wind-powered energy source. Use of Forecast Information Regarding Energy Source Availability Allows the System to Adjust an Operating Parameter, which can Help to Maintain Consistent Operation and Improve System Reliability and Component Lifetime (e.g., when Excess Energy is Available so that Heating Element Temperatures can be Reduced). 263. A thermal energy storage system, comprising:a storage medium (14,209) configured to store thermal energy obtained using input energy from an energy source (2,201);a fluid movement device configured to move fluid through the storage medium to heat the fluid and provide the heated fluid (20) to a load system (22); anda control system (15,1502) configured toreceive forecast information regarding availability of the energy source, andbased on the forecast information, adjust an operating parameter of the thermal energy storage system. 264. The thermal energy storage system of claim 263, wherein the input energy is electrical energy, and further comprising a heating element configured to convert a portion of the input energy to a portion of the thermal energy. Supercharging the Thermal Storage Medium Allows the Specified Output Temperature or Energy of the System to be Maintained Through a Period of Lower Energy Source Availability. 265. The thermal energy storage system of claim 264, wherein the control system is configured to operate the heating element at an increased electrical power level during a period of availability of the energy source, when the forecast information indicates an upcoming reduction in availability of the energy source. Reduced Heater Power Level when Power is Expected to be Available for a Longer Time than Normal Allows Reliable Output to be Maintained while Reducing Stress on the Heating Elements and Storage Medium. 266. The thermal energy storage system of claim 264, wherein the control system is configured to operate the heating element at a decreased electrical power level during a period of availability of the energy source, when the forecast information indicates an upcoming increase in availability of the energy source. 267. The thermal energy storage system of claim 263, further comprising an auxiliary heater system configured to heat at least a portion of the fluid at a location outside of the storage medium, wherein the control system is configured to direct excess input energy to the auxiliary heater system during a period of energy availability. When a High Amount of Input Energy is Forecast, Using Excess Energy to Heat the Fluid Using an Auxiliary Heater while Reducing the Thermal Energy in the Storage Medium May Reduce Wear and Tear on the Storage Medium and its Heating Elements. 268. The thermal energy storage system of claim 267, wherein the forecast information indicates an upcoming increase in availability of the energy source and the control system is configured to reduce an amount of thermal energy stored in the storage medium commensurately with an increase in thermal energy provided by the auxiliary heater system. When a Low Amount of Input Energy is Forecast, Using the Auxiliary Heater May Allow a Delay in when the Thermal Storage Will Need to be Discharged, which Helps to Provide Continuous Power During the Low Input Energy Period. 269. The thermal energy storage system of claim 267, wherein the forecast information indicates an upcoming decrease in availability of the energy source and the control system is configured to maintain or increase an amount of thermal energy stored in the storage medium during the period of energy availability. 270. The thermal energy storage system of claim 267, wherein the auxiliary heater system comprises a heater positioned along a bypass line configured to convey a portion of the fluid to the load system without passing the portion through the storage medium. 271. The thermal energy storage system of claim 267, wherein the auxiliary heater system comprises a heater positioned along an outlet line between an outlet of the storage medium and an inlet of the load system. 272. The thermal energy storage system of claim 263, wherein the control system is configured to adjust a flow rate of the fluid through the storage medium based on the forecast information. 273. The thermal energy storage system of claim 263, wherein the control system is configured to reduce a flow rate of the fluid through the storage medium when the forecast information indicates an upcoming decrease in availability of the energy source. 274. The thermal energy storage system of claim 263, wherein the control system is configured to receive the forecast information from an energy source control system. 275. The thermal energy storage system of claim 263, wherein the control system is configured to receive the forecast information from an analytics system external to the control system. 276. The thermal energy storage system of claim 263, wherein the forecast information relates to relative time periods of energy source availability and unavailability. 277. The thermal energy storage system of claim 263, wherein the forecast information relates to a relative magnitude of energy available from the energy source. 278. The thermal energy storage system of claim 263, wherein the energy source is a source of intermittent availability. 279. The thermal energy storage system of claim 263, wherein the energy source comprises a solar energy source. 280. The thermal energy storage system of claim 263, wherein the energy source comprises a wind-powered energy source. Use of Forecast Information Regarding Energy Source Availability Allows the System to Adjust an Operating Parameter, which can Help to Maintain Consistent Operation and in Some Cases Improve System Reliability and Component Lifetime (e.g., when Excess Energy is Available so that Heating Element Temperatures can be Reduced). 281. A method of storing and delivering thermal energy, comprising:receiving input energy from an energy source (2,201);storing in a storage medium (14,209) thermal energy obtained using the input energy;moving fluid through the storage medium to heat the fluid for delivery to a load system (22);receiving forecast information regarding availability of the energy source; andbased on the forecast information, adjusting an operating parameter associated with moving the fluid through the storage medium. Supercharging the Thermal Storage Medium Allows the Specified Output Temperature or Energy of the System to be Maintained Through a Period of Lower Energy Source Availability. 282. The method of claim 281, wherein adjusting an operating parameter comprises, during a period of availability of the energy source when the forecast information indicates an upcoming reduction in availability of the energy source, operating at an increased electrical power level a heating element associated with the storage medium. Reduced Heater Power Level when a High Amount or Duration Input Energy is Forecast to be Available Allows the Same Output to be Maintained while Reducing Stress on the Heating Element and Storage Medium. 283. The method of claim 281, wherein adjusting an operating parameter comprises, during a period of availability of the energy source when the forecast information indicates an upcoming increase in availability of the energy source, operating at a decreased electrical power level a heating element associated with the storage medium. 284. The method of claim 281, wherein adjusting an operating parameter comprises, during a period of energy source availability, directing excess energy to an auxiliary heater system configured to heat at least a portion of the fluid at a location outside of the storage medium. When a High Amount of Input Energy is Forecast, Using Excess Energy to Heat the Fluid Using an Auxiliary Heater while Reducing the Thermal Energy in the Storage Medium May Reduce Wear and Tear on the Storage Medium and its Heating Elements. 285. The method of claim 284, wherein adjusting an operating parameter comprises, when the forecast indicates an upcoming increase in availability of the energy source, reducing an amount of thermal energy stored in the storage medium commensurately with an increase in thermal energy provided by the auxiliary heater system. When a Low Amount of Input Energy is Forecast, Using the Auxiliary Heater May Allow a Delay in when the Thermal Storage Will Need to be Discharged, which Helps to Provide Continuous Power During the Low Input Energy Period. 286. The method of claim 284, wherein adjusting an operating parameter comprises, when the forecast indicates an upcoming decrease in availability of the energy source, controlling a heated fluid discharge rate to maintain energy output over a determined period of time. 287. The method of claim 284, wherein the auxiliary heater system comprises a heater positioned along a bypass line configured to convey a portion of the fluid to the load system without passing the portion through the storage medium. 288. The method of claim 284, wherein the auxiliary heater system comprises a heater positioned along an outlet line between an outlet of the storage medium and an inlet of the load system. 289. The method of claim 281, wherein adjusting the operating parameter comprises adjusting a flow rate of the fluid through the storage medium based on the forecast information. 290. The method of claim 281, wherein adjusting the operating parameter comprises reducing a flow rate of the fluid through the storage medium when the forecast information indicates an upcoming decrease in availability of the energy source. 291. The method of claim 281, wherein receiving forecast information comprises receiving the forecast information from an energy source control system. 292. The method of claim 281, wherein receiving forecast information comprises receiving the forecast information from an analytics system. 293. The method of claim 281, wherein the forecast information relates to relative time periods of energy source availability and unavailability. 294. The method of claim 281, wherein the forecast information relates to a relative magnitude of energy available from the energy source. 295. The method of claim 281, wherein the energy source is a source of intermittent availability. 296. The method of claim 281, wherein the energy source comprises a solar energy source. 297. The method of claim 281, wherein the energy source comprises a wind-powered energy source. DC-DC Conversion Systems and Methods DC-DC Conversion Allows for a Lower-Loss Method of Power Transmission than Conventional AC Power Transfer Due to Smaller Eddy Currents and Lower Resistances in the System as the Power Generated by the Generator Circuits Varies in Time. 298. A thermal storage system, including:a thermal storage medium (3111);a heating element (3112) positioned to heat the thermal storage medium; anda power transfer system (3103A-C,3101,3102), comprising:a plurality of generator circuits (3103A-C) configured to generate a plurality of time-varying direct current (DC) voltages;a first converter circuit (3101) that includes a plurality of first converter circuits (3203A-C), each first converter circuit including:a first input circuit (3401) configured to receive one of the time-varying DC voltages, and a first output circuit (3419) galvanically isolated from the input circuit and configured to generate a first corresponding DC voltage derived from the time-varying DC voltage received by the first input circuit, wherein the first converter circuit is configured to combine the first corresponding DC voltages of the first output circuits to generate a transmit voltage and drive a transmission line; anda second converter circuit (3102) that includes a plurality of second converter circuits, each second converter circuit including:a second input circuit (3401) configured to receive a portion of the transmit voltage, and a second output circuit (3419) galvanically isolated from the second input circuit and configured to generate a second corresponding DC voltage derived from the portion of the transmit voltage received by the second input circuit; anda common power bus (3105) coupled to the second output circuits and to the heating element;wherein the second converter circuit is configured to deliver the second corresponding DC voltages of the second output circuits to the heating element via the common power bus. 299. The thermal storage system of claim 298, wherein each first converter circuit further includes a transformer, and wherein the first input circuit is further configured to induce, using the time-varying DC voltage received by the first input circuit, a first current in a primary coil of the transformer, and wherein the first output circuit is further configured to generate the first corresponding DC voltage using a second current induced in a secondary coil of the transformer. 300. The thermal storage system of claim 299, wherein to generate the first corresponding DC voltage, the first output circuit is further configured to:rectify the second current to generate an internal supply voltage; andgenerate the first corresponding DC voltage using the internal supply voltage. 301. The thermal storage system of claim 298, wherein the plurality of generator circuits includes a plurality of photovoltaic cells configured to generate the plurality of time-varying DC voltages based on an illumination of the photovoltaic cells. Power Transfer System: Maintains the Voltage Across any One of the Converter Circuits Smaller, Allowing for Smaller and Less Expensive Components; Allows for the Creation of a Larger Transmission Voltage without Using a Traditional Step-Up Transformer which could Create Additional Power Transfer Losses; and Prevents the Draw of Excessive Current from the Generator Circuits by the Power Transfer System. 302. A power transfer system, comprising:a plurality of generator circuits (3103A-C) configured to generate a plurality of time-varying direct current (DC) voltages;a first converter circuit (3101) that includes a plurality of first converter circuits (3203A-C), each first converter circuit including:a first input circuit (3401) configured to receive one of the time-varying DC voltages, and a first output circuit (3419) galvanically isolated from the input circuit and configured to generate a first corresponding DC voltage derived from the time-varying DC voltage received by the first input circuit, wherein the first converter circuit is configured to combine the first corresponding DC voltages of the first output circuits to generate a transmit voltage and drive a transmission line (3106); anda second converter circuit (3102) that includes a plurality of second converter circuits, each second converter circuit including:a second input circuit (3401) configured to receive a portion of the transmit voltage, and a second output circuit (3419) galvanically isolated from the second input circuit and configured to generate a second corresponding DC voltage derived from the portion of the transmit voltage received by the second input circuit, wherein the second converter circuit is configured to deliver the second corresponding DC voltages of the second output circuits on a common power bus; anda load (3104) coupled to the common power bus. 303. The power transfer system of claim 302, wherein each first converter circuit further includes a transformer, and wherein the first input circuit is further configured to induce, using the time-varying DC voltage received by the first input circuit, a first current in a primary coil of the transformer, and wherein the first output circuit is further configured to generate the first corresponding DC voltage using a second current induced in a secondary coil of the transformer. 304. The power transfer system of claim 303, wherein to generate the first corresponding DC voltage, the first output circuit is further configured to:rectify the second current to generate an internal supply voltage; andgenerate the first corresponding DC voltage using the internal supply voltage. 305. The power transfer system of claim 302, wherein the load includes a heating element configured to receive the second corresponding DC voltages via the common power bus to heat a thermal storage medium. 306. The power transfer system of claim 305, wherein the load includes an electric vehicle charger configured to charge at least one battery using the second corresponding DC voltages. Apparatus Allows for the Creation of a Larger Transmission Voltage without Using a Traditional Step-Up Transformer which could Create Additional Power Transfer Losses, and Prevents the Draw of Excessive Current from the Generator Circuits by the Power Transfer System. 307. An apparatus, comprising:a first plurality of converter circuits (3203A-C), each converter circuit including:an input circuit (3401) configured to receive a direct current (DC) input voltage from a renewable energy source; andan output circuit (3419) galvanically isolated from the input circuit and configured to generate a DC output voltage derived from the DC input voltage;wherein the output circuits of the first plurality of converter circuits are coupled in series to combine respective DC output voltages to produce a transmit voltage; anda thermal storage unit (3104) including a heating element (3112) configured to receive the transmit voltage to heat a thermal storage medium (3111). 308. The apparatus of claim 307, wherein each converter circuit further includes a transformer, and wherein the input circuit is further configured to induce, using the DC input voltage, a first current in a primary coil of the transformer, and wherein the output circuit is further configured to generate the DC output voltage using a second current induced in a secondary coil of the transformer. 309. The apparatus of claim 308, wherein to generate the DC output voltage using the second current, the output circuit is further configured to:rectify the second current to generate an internal supply voltage; andgenerate the DC output voltage using the internal supply voltage. 310. The apparatus of claim 307, wherein the renewable energy source includes a plurality of photovoltaic cells configured to generate the DC input voltage based on an illumination of the photovoltaic cells. Method Allows for the Creation of a Larger Transmission Voltage without Using a Traditional Step-Up Transformer which could Create Additional Power Transfer Losses, and Prevents the Draw of Excessive Current from the Generator Circuits by the Power Transfer System. 311. A method, comprising:receiving, by an input circuit (3401) of a given converter circuit of a plurality of converter circuits (3203A-C), a direct current (DC) input voltage from a renewable energy source (3202A-C);generating, by an output circuit (3419) of the given circuit that is galvanically isolated from the input circuit, a DC output voltage derived from the DC input voltage;combining respective DC output voltages by coupling the output circuits of the first plurality of converter circuits in series to produce a transmit voltage (3108); andheating a thermal storage medium (3104) by a heating element (3112) using the transmit voltage. 312. The method of claim 311, further comprising adding the second plurality of DC voltages to generate the transmit voltage. 313. The method of claim 311, wherein generating the DC output voltage includes:inducing, by the input circuit using the DC input voltage, a first current in a primary coil of a transformer included in the given converter circuit; andgenerating, by the output circuit using a second current in a secondary coil of the transformer, the DC output voltage, wherein the second current in the secondary coil is based on the first current in the primary coil of the transformer. 314. The method of claim 313, further comprising:rectifying, by the output circuit, the second current to generate an internal supply voltage; andgenerating, by the output circuit, the DC output voltage using the internal supply voltage. Apparatus: Maintains the Voltage Across any One of the Converter Circuits Smaller, Allowing for Smaller and Less Expensive Components; Allows for the Creation of a Larger Transmission Voltage without Using a Traditional Step-Up Transformer which could Create Additional Power Transfer Losses; and Prevents the Draw of Excessive Current from the Generator Circuits by the Power Transfer System. 315. An apparatus, comprising:a plurality of first converter circuits (3203A-C), each first converter circuit including:a first input circuit (3401) configured to receive a direct current (DC) input voltage from a renewable energy source; anda first output circuit (3419) galvanically isolated from the first input circuit and configured to generate a DC output voltage derived from the DC input voltage, wherein the output circuits of the first plurality of converter circuits are coupled in series to combine respective DC output voltages to produce a transmit voltage;a plurality of second converter circuits (3302A-C) coupled in series across the transmit voltage to generate a plurality of voltage portions, wherein each second converter circuit includes:a second input circuit (3401) configured to receive a corresponding portion of the plurality of voltage portions; anda second output circuit (3419) galvanically isolated from the second input circuit and configured to generate, using the corresponding portion, a DC load voltage; anda thermal storage unit (3104) configured to heat a thermal storage medium (3111) using respective DC load voltages from the second plurality of converter circuits. 316. The apparatus of claim 315, wherein each first converter circuit further includes a transformer, and wherein the first input circuit is further configured to induce, using the DC input voltage, a first current in a primary coil of the transformer, and wherein the first output circuit is further configured to generate the DC output voltage using a second current induced in a secondary coil of the transformer. 317. The apparatus of claim 316, wherein to generate the DC output voltage, the first output circuit is further configured to:rectify the second current to generate an internal supply voltage; andgenerate the DC output voltage using the internal supply voltage. 318. The apparatus of claim 315, wherein the renewable energy source includes a plurality of photovoltaic cells configured to generate the DC input voltage based on an illumination of the photovoltaic cells. Apparatus Allows for the Creation of a Larger Transmission Voltage without Using a Traditional Step-Up Transformer which could Create Additional Power Transfer Losses, and Prevents the Draw of Excessive Current from the Generator Circuits by the Power Transfer System. 319. An apparatus, comprising:a first plurality of converter circuits (3202A-C), each converter circuit including:a first input circuit (3401) configured to receive a direct current (DC) input voltage from a DC voltage source; anda first output circuit (3419) galvanically isolated from the first input circuit and configured to generate a DC output voltage based on the DC input voltage; andwherein the first plurality of converter circuits are coupled in series such that the DC output voltages are combined to produce a transmit voltage (3108). 320. The apparatus of claim 319, further comprising a load unit including an electric vehicle charger configured to charge at least one battery using the transmit voltage. 321. The apparatus of claim 320, further comprising:a second plurality of converter circuits (3302A-C) coupled in series across the transmit voltage, wherein each of the second plurality of converter circuits includes:a second input circuit (3401) configured to receive a corresponding portion the transmit voltage; anda second output circuit (3419) galvanically isolated from the second input circuit and configured to generate, using the corresponding portion of the transmit voltage, a DC load voltage; anda load unit (3306A-B) including an electric vehicle charger configured to charge at least one battery (3208) using at least one of the plurality of DC load voltages. Calcination Systems and Methods Calcium Carbonate Calcination. 322. A calcination system, comprising:a thermal energy storage (TES) system configured to store thermal energy derived from a renewable energy source, wherein the TES system includes:a heating element configured to heat a storage medium using electricity from the renewable energy source; anda blower configured to heat a non-combustive fluid including carbon dioxide by circulating the non-combustive fluid through the heated storage medium;the calcination system further comprising a calciner configured to release carbon dioxide from a supply of calcium carbonate within the calciner, by:receiving thermal energy obtained from the heated non-combustive fluid; andapplying the received thermal energy to the calcium carbonate. 323. The calcination system of claim 322, wherein the calciner is configured to apply the received thermal energy by:injecting calcium carbonate via a first inlet of the calciner; andinjecting, via a second inlet underneath the first inlet, the heated non-combustive fluid in an up-flow configuration that suspends the injected calcium carbonate within the calciner. 324. The calcination system of claim 322, further comprising:a heat exchanger configured to:heat a second fluid by transferring thermal energy from the heated non-combustive fluid into the second fluid; andwherein the calciner is configured to apply the received thermal energy by:injecting the heated second fluid into the calciner to heat the calcium carbonate. 325. The calcination system of claim 322, further comprising:a recirculation system configured to:recover, from the calciner, carbon dioxide produced by the calcination process; andrecirculate the recovered carbon dioxide to the TES system for inclusion in the non-combustive fluid. 326. The calcination system of claim 322, further comprising:a pre-heater configured to:receive additional thermal energy obtain from the heated non-combustive fluid;apply the additional thermal energy to heat calcium carbonate to a first temperature; andprovide the heated calcium carbonate to the calciner for heating to a second temperature that is higher than the first temperature. Material Activation System. 327. A material activation system, comprising:a thermal energy storage (TES) system configured to store thermal energy derived from an energy source, by:heating a storage medium using energy from the renewable energy source; andcirculating a non-combustive fluid through the heated storage medium; anda material heating system configured to:receive thermal energy derived from the circulated non-combustive fluid; andapply the received thermal energy to a raw material to produce an activated material. 328. The material activation system of claim 327, wherein the material heating system is configured to:receive the circulated non-combustive fluid at a first inlet in the material heating system;inject the raw material via a second inlet positioned above the first inlet in the material heating system; anddirect the fluid in an up-flow configuration such that the raw material is suspended in the material heating system. 329. The material activation system of claim 327, further comprising:a heat exchanger configured to:receive the circulated non-combustive fluid from the TES system;transfer heat from the circulated non-combustive fluid into a second fluid; andprovide the heated second fluid to the material heating system for applying the thermal energy to the raw material. 330. The material activation system of claim 329, further comprising:a bypass configured to inject a portion of the circulated non-combustive fluid received from the TES system into the second fluid provided to the material heating system. 331. The material activation system of claim 327, further comprising:a pre-heater configured to:apply thermal energy derived from the circulated non-combustive fluid to heat the raw material to a first temperature; andprovide the heated raw material as an input to the material heating system for heating to a second temperature. 332. The material activation system of claim 327, further comprising:a recirculation system configured to:recirculate an exhaust fluid output from the material heating system to the TES system as an input. 333. The material activation system of claim 332, further comprising:a cooling cyclone configured to:receive the activated material from the material heating system; andreduce a temperature of the activated material; andwherein the recirculation system is configured to:collect, from the cooling cyclone, the exhaust fluid for recirculation. 334. The material activation system of claim 333, wherein the recirculation system includes:a filter coupled between the material heating system and the TES system, wherein the filter is configured to remove particulate from the exhaust fluid prior to the exhaust fluid being provided to the TES system. 335. The material activation system of claim 327, wherein the material heating system is configured to perform a calcination process that transforms calcium carbonate as the raw material into calcium oxide as the activated material for cement production. 336. The material activation system of claim 335, further comprising a recirculation system configured to recirculate carbon dioxide produced by the calcination process to the TES system for use as the non-combustive fluid. 337. The material activation system of claim 327, wherein the material heating system is configured to perform a dehydroxylation process that removes hydroxide from clay minerals as the raw material to produce activated clay as the activated material. 338. The material activation system of claim 337, further comprising:an atmosphere reduction system coupled to the material heating system and configured to reduce an amount of oxygen in contact with the activated clay. 339. The material activation system of claim 327, wherein the material heating system is configured to implement a Bayer process that transforms bauxite as the raw material to produce aluminum oxide as the activated material. 340. The material activation system of claim 339, wherein the material heating system is configured to:Implement a first stage of the Bayer process that includes heating the bauxite to a temperature within a range from 300° C. to 480° C. and at a first pressure within a range of 6 bar to 8 bar;implement a second stage of the Bayer process that includes elevating a temperature of the bauxite within a temperature range from 750° C. to 950° C. and a second pressure lower than the first pressure; andrecirculate, from the second stage to the first stage, the thermal energy derived from the circulated non-combustive fluid. 341. The material activation system of claim 327, further comprising:a burner configured to supply combustion energy to the material heating system in addition to the thermal energy supplied by the TES system. 342. The material activation system of claim 327, further comprising:a steam cycle system that includes:a heat exchanger configured to produce steam from thermal energy recovered from the material heating system; and a stream turbine configured to generate electricity from the produced steam. 343. The material activation system of claim 327, wherein the TES system is configured to:provide the circulated non-combustive fluid to the material heating system at a temperate within a range of from 600° C. to 1100° C. 344. The material activation system of claim 327, wherein the non-combustive fluid is carbon dioxide. 345. The material activation system of claim 327, wherein the storage medium includes brick. 346. The material activation system of claim 327, wherein the heating element includes one or more ceramic resistive heaters. Method of Material Activation. 347. A method for material activation, comprising:receiving, by a thermal energy storage (TES) system of a material activation system, energy supplied by an energy source;storing, by the TES system, the received energy as thermal energy by heating a storage medium with the received energy;providing, by the TES system to a material heating system of the material activation system, the stored thermal energy by circulating a non-combustive fluid through the heated storage medium; andimplementing, by the material heating system, a material activation process that includes applying the provided thermal energy to a raw material to produce an activated material. 348. The method of claim 347, further comprising:recovering, by the material activation system, thermal energy from an output of material heating system; andrecirculating, to the TES system, a fluid including the recovered thermal energy. 349. The method of claim 347, wherein the martial activation process produces calcium oxide and carbon dioxide from calcium carbonate; and wherein the method further comprises:recirculating, by the material activation system, the carbon dioxide to the TES system for use as the non-combustive fluid. 350. The method of claim 347, wherein the martial activation process produces activated clay and hydroxide from clay minerals; andwherein the method further comprises:reducing, by an atmosphere reduction zone of the material activation system, an amount of oxygen in contact with the activated clay. Material Activation System. 351. A material activation system, comprising:a non-combustive means for heating a storage medium using energy from a variable energy source;a means for transferring thermal energy from the storage medium to a fluid; anda means for applying the transferred thermal energy from the fluid to a raw material to produce an activated material. Calcination System. 352. A calcination system, comprising:a thermal energy storage (TES) system configured to store thermal energy derived from an energy source, wherein the TES system includes:a heating element configured to heat a storage medium using electricity from the energy source; anda blower configured to heat a non-combustive fluid by circulating the non-combustive fluid through the heated storage medium;the calcination system further comprising a calciner configured to remove carbon dioxide from a supply of calcium carbonate within the calciner, by:receiving thermal energy obtained from the heated non-combustive fluid; andapplying the received thermal energy to the calcium carbonate. System Using Thermal Energy Storage Discharge for a Solid Oxide Electrolysis System to Efficiently Produce Hydrogen from Electrolysis of Water. 353. A system, comprising:a thermal energy storage (TES) system (4801) configured to store thermal energy derived from a renewable energy source (4903), wherein the TES system includes:a storage medium configured to store thermal energy; anda heating element configured to heat the storage medium using electricity from the renewable energy source; anda fluid movement system (213,4223) configured to move a fluid through the storage medium to heat the fluid to a temperature in a specified temperature range; andan electrolysis system (4803), wherein the electrolysis system includes:a plurality of solid oxide cells (4803) configured to electrolyze water to produce hydrogen when an electric potential is provided to the solid oxide cells; anda sweep path across the solid oxide cells, wherein the sweep path is configured to circulate the fluid from the fluid movement system to transfer heat to the solid oxide cells. 354. The system of claim 353, wherein the fluid comprises a mixture of oxygen and nitrogen. 355. The system of claim 353, wherein the fluid has a volume percentage of oxygen that is above 25% and below 60%. 356. The system of claim 353, wherein a volume percentage of hydrogen in a product fluid produced by electrolysis is greater than a volume percentage of hydrogen in the water provided to the solid oxide cells. 357. The system of claim 353, wherein the water provided to the solid oxide cells comprises water and hydrogen. 358. The system of claim 353, wherein the water comprises at least 90% water. 359. The system of claim 353, wherein the specified temperature range is 800° C. to 900° C. 360. The system of claim 353, wherein the water is at a temperature below the temperature of the fluid but above 800° C. 361. The system of claim 353, wherein the fluid has a flow rate of at least 1500 kg/hr. 362. The system of claim 353, wherein the fluid has a flow rate between 1500 kg/hr and 2000 kg/hr. 363. The system of claim 353, wherein hydrogen produced by electrolysis is at a temperature above a temperature of the water. 364. The system of claim 353, wherein the electric potential provided to the solid oxide cells is between 1 volt and 3 volts. 365. The system of claim 353, wherein the fluid provides an amount of heat sufficient to maintain electrolysis of water in the solid oxide cells. 366. The system of claim 353, further comprising a steam generator (4805) configured to condense the hydrogen and generate steam by exchanging heat from the hydrogen with water. 367. The system of claim 353, wherein at least some of the steam generated by the steam generator (4805) is configured to be recirculated to the solid oxide cells. 368. The system of claim 367, wherein the recirculated fluid includes at least some hydrogen gas. 369. The system of claim 368, wherein at least some of the condensed hydrogen is configured to be stored. 370. The system of claim 353, wherein the fluid is enriched with at least some of oxygen produced by the electrolysis of water in the solid oxide cells. 371. The system of claim 370, wherein the oxygen enriched fluid has a volume percentage of oxygen above the volume percentage of oxygen in the fluid. 372. The system of claim 370, wherein a temperature of the hydrogen is near a temperature of the oxygen enriched fluid. 373. The system of claim 370, wherein the oxygen enriched fluid includes oxygen and nitrogen. 374. The system of claim 370, wherein a temperature of the oxygen enriched fluid is between a temperature of the water and a temperature of the fluid. 375. The system of claim 370, wherein the oxygen enriched fluid is provided to the thermal energy storage system. 376. The system of claim 370, further comprising a steam generator (4807) configured to generate steam by exchanging heat from the oxygen enriched fluid with water. 377. The system of claim 353, wherein the water comprises water and carbon dioxide. 378. The system of claim 377, wherein the water and carbon dioxide is configured to be converted to carbon monoxide and hydrogen by electrolysis in the solid oxide cells. 379. The system of claim 378, further comprising a syngas conversion system (4109) configured to produce a synthetic hydrocarbon fluid from the produced hydrogen and carbon monoxide. Method Using Thermal Energy Storage Discharge for a Solid Oxide Electrolysis System to Efficiently Produce Hydrogen from Electrolysis of Water. 380. A method, comprising:heating a storage medium using heating elements that convert electricity from a renewable energy source (4903) to heat;circulating a fluid through the storage medium to heat the fluid to a temperature in a specified temperature range;circulating the fluid across a plurality of solid oxide cells (4803);providing water to the solid oxide cells (4803); andproviding an electric potential to the solid oxide cells (4803) to electrolyze the water and generate hydrogen. 381. The method of claim 380, wherein the fluid comprises a mixture of oxygen and nitrogen. 382. The method of claim 380, wherein the fluid has a volume percentage of oxygen that is above 25% and below 60%. 383. The method of claim 380, wherein a volume percentage of hydrogen in a product fluid produced by electrolysis is greater than a volume percentage of hydrogen in the water provided to the solid oxide cells. 384. The method of claim 380, wherein the water provided to the solid oxide cells comprises water and hydrogen. 385. The method of claim 380, wherein the water comprises at least 90% water. 386. The method of claim 380, wherein the specified temperature range is 800° C. to 900° C. 387. The method of claim 380, wherein the water is at a temperature below the temperature of the fluid but above 800° C. 388. The method of claim 380, wherein the fluid has a flow rate of at least 1500 kg/hr. 389. The method of claim 380, wherein the fluid has a flow rate between 1500 kg/hr and 2000 kg/hr. 390. The method of claim 380, wherein hydrogen produced by electrolysis is at a temperature above a temperature of the water. 391. The method of claim 380, wherein the electric potential provided to the solid oxide cells is between 1 volt and 3 volts. 392. The method of claim 380, wherein the fluid provides an amount of heat sufficient to maintain electrolysis of water in the solid oxide cells. 393. The method of claim 380, further comprising providing the hydrogen to a steam generator (4805) to condense the hydrogen and generate steam by exchanging heat from the hydrogen with water. 394. The method of claim 393, further comprising adding a recirculated fluid to the water provided to the solid oxide cells, wherein the recirculated fluid includes at least some of the steam generated by the steam generator. 395. The method of claim 394, wherein the recirculated fluid includes at least some hydrogen gas. 396. The method of claim 393, further comprising storing at least some of the condensed hydrogen. 397. The method of claim 380, wherein the electrolysis of water produces oxygen, and wherein the fluid is enriched with at least some of the produced oxygen. 398. The method of claim 397, wherein a temperature of the hydrogen is near a temperature of the oxygen enriched fluid. 399. The method of claim 397, wherein the oxygen enriched fluid has a volume percentage of oxygen above the volume percentage of oxygen in the fluid. 400. The method of claim 397, wherein the oxygen enriched fluid includes oxygen and nitrogen. 401. The method of claim 397, wherein a temperature of the oxygen enriched fluid is between a temperature of the water and a temperature of the fluid. 402. The method of claim 397, further comprising providing the oxygen enriched fluid to the thermal energy storage system, and:implementing the oxygen enriched fluid in continued operation of the thermal energy storage system; orimplementing the oxygen enriched fluid in the conversion of the input electricity to stored thermal energy. 403. The method of claim 397, further comprising providing the oxygen enriched fluid to a steam generator (4807) to generate steam by exchanging heat from the oxygen enriched fluid with water. 404. The method of claim 380, wherein the water provided to the solid oxide cells comprises water and carbon dioxide. 405. The method of claim 404, wherein the water and carbon dioxide is converted to carbon monoxide and hydrogen by electrolysis in the solid oxide cells. 406. The method of claim 405, further comprising providing the hydrogen and carbon monoxide to a syngas conversion system (4109) to produce a synthetic hydrocarbon fluid. System Using Stored Thermal Energy in a Fuel Cell System to Convert Hydrogen to Electricity and Water. 407. A system, comprising:a thermal energy storage (TES) system (5001) configured to store thermal energy derived from a renewable energy source (4903), wherein the TES system includes:a storage medium configured to store thermal energy; anda heating element configured to heat the storage medium using electricity from the renewable energy source; anda fluid movement system (213,4223) configured to move a fluid through the storage medium to heat the fluid to a temperature in a specified temperature range; anda fuel cell system (5007), wherein the fuel cell system includes:a plurality of solid oxide cells (5007) configured to generate electricity and water when hydrogen is provided to the solid oxide cells; anda sweep path across the solid oxide cells (5007), wherein the sweep path is configured to circulate the fluid from the fluid movement system to remove heat from the solid oxide cells. 408. The system of claim 407, wherein the fluid comprises a mixture of oxygen and nitrogen. 409. The system of claim 407, wherein the fluid has a volume percentage of oxygen that is above 25% and below 60%. 410. The system of claim 407, wherein the specified temperature range is 600° C. and 700° C. 411. The system of claim 407, wherein the fluid has a flow rate of at least 1500 kg/hr. 412. The system of claim 407, wherein the fluid has a flow rate between 1500 kg/hr and 2000 kg/hr. 413. The system of claim 407, further comprising a heat exchanger (5013) configured to heat hydrogen fed to the solid oxide cells with the fluid. 414. The system of claim 407, wherein the hydrogen provided to the solid oxide cells includes at least some steam. 415. The system of claim 407, wherein the fluid is configured to maintain a temperature of the solid oxide cells. 416. The system of claim 407, wherein the electricity generated is direct current electricity. 417. The system of claim 407, wherein at least a portion of the residual hydrogen from the solid oxide cells is configured to be recirculated to the solid oxide cells. 418. The system of claim 407, wherein at least a portion of the fluid that sweeps through the solid oxide cells is provided to the TES system. Method Using Stored Thermal Energy in a Fuel Cell System to Convert Hydrogen to Electricity and Water. 419. A method, comprising:heating a storage medium using heating elements that convert electricity from a renewable energy source (4903) to heat;circulating a fluid through the storage medium to heat the fluid to a temperature in a specified temperature range;circulating the fluid across a plurality of solid oxide cells (5007);providing hydrogen to the solid oxide cells (5007); andgenerating electricity and water from the solid oxide cells (5007). 420. The method of claim 419, wherein the fluid comprises a mixture of oxygen and nitrogen. 421. The method of claim 419, wherein the fluid has a volume percentage of oxygen that is above 25% and below 60%. 422. The method of claim 419, wherein the specified temperature range is 600° C. and 700° C. 423. The method of claim 419, wherein the fluid has a flow rate of at least 1500 kg/hr. 424. The method of claim 419, wherein the fluid has a flow rate between 1500 kg/hr and 2000 kg/hr. 425. The method of claim 419, further comprising heating hydrogen fed to the solid oxide cells with the fluid in a heat exchanger (5013). 426. The method of claim 419, further comprising adding steam to the hydrogen provided to the solid oxide cells. 427. The method of claim 419, wherein the fluid removes heat from the solid oxide cells. 428. The method of claim 419, wherein the electricity generated is direct current electricity. 429. The method of claim 419, further comprising recirculating at least a portion of the residual hydrogen produced from the solid oxide cells to the solid oxide cells. 430. The method of claim 419, further comprising providing at least a portion of the fluid that sweeps through the solid oxide cells to the storage medium. System in which Solid Oxide Cells are Reversible to be Used for Either Electrolysis or Fuel Cell Operations, Allowing Fluid to be Constantly Provided to the Cells to Maintain the Cells at Elevated Temperatures while Switching Between Modes of Operation. 431. A system, comprising:a thermal energy storage (TES) system (4801) configured to store thermal energy derived from a renewable energy source (4903), wherein the TES system includes:a storage medium configured to store thermal energy; anda heating element configured to heat the storage medium using electricity from the renewable energy source; anda fluid movement system (213,4223) configured to move a fluid through the storage medium to heat the fluid to a temperature in a specified temperature range; anda plurality of solid oxide cells (4803), wherein the solid oxide cells are configured to:electrolyze water to produce hydrogen when an electric potential is provided to the solid oxide cells;generate electricity and water when hydrogen is provided to the solid oxide cells; anda sweep path across the solid oxide cells, wherein the sweep path is configured to circulate the fluid from the fluid movement system to transfer heat between the fluid and the solid oxide cells. 432. The system of claim 431, wherein the fluid has a volume percentage of oxygen that is above 25% and below 60%. 433. The system of claim 431, wherein a volume percentage of hydrogen in a product fluid produced by electrolysis is greater than a volume percentage of hydrogen in the water provided to the solid oxide cells. 434. The system of claim 431, wherein the water provided to the solid oxide cells comprises water and hydrogen. 435. The system of claim 431, wherein the water for electrolysis comprises at least 90% water. 436. The system of claim 431, wherein the specified temperature range is 800° C. to 900° C. 437. The system of claim 431, wherein the specified temperature range is 600° C. and 700° C. 438. The system of claim 431, wherein the water for electrolysis reaction is at a temperature below the temperature of the fluid but above 800° C. 439. The system of claim 431, wherein the fluid has a flow rate of at least 1500 kg/hr. 440. The system of claim 431, wherein the fluid has a flow rate between 1500 kg/hr and 2000 kg/hr. 441. The system of claim 431, wherein hydrogen produced by electrolysis is at a temperature above a temperature of the water for electrolysis. 442. The system of claim 431, wherein the electric potential provided to the solid oxide cells for electrolysis is between 1 volt and 3 volts. 443. The system of claim 431, wherein the fluid provides an amount of heat sufficient to maintain electrolysis of water in the solid oxide cells. 444. The system of claim 431, wherein the electrolysis of water produces oxygen, and wherein the fluid is enriched with at least some of the produced oxygen. 445. The system of claim 444, wherein the oxygen enriched fluid has a volume percentage of oxygen above the volume percentage of oxygen in the fluid. 446. The system of claim 444, wherein a temperature of the hydrogen produced by electrolysis is near a temperature of the oxygen enriched fluid produced by electrolysis. 447. The system of claim 444, wherein the oxygen enriched fluid includes oxygen and nitrogen. 448. The system of claim 444, wherein a temperature of the oxygen enriched fluid is between a temperature of the water for electrolysis and a temperature of the fluid. 449. The system of claim 444, wherein the oxygen enriched fluid is configured to be provided to the thermal energy storage system, and wherein the thermal energy storage system is configured to:implement the oxygen enriched fluid in continued operation of the thermal energy storage system; orimplement the oxygen enriched fluid in the conversion of the input electricity to stored thermal energy. System Providing Heated Fluid for Electrolysis, the Heat being Provided from a High-Efficiency TES System and Used to Increase Efficiency of Electrolysis Reaction. 450. A thermal energy storage (TES) system (4801), comprising:a storage medium configured to store thermal energy; anda heating element configured to heat the storage medium using electricity from a renewable energy source (4903); anda fluid movement system (213,4223) configured to move a fluid through the storage medium to heat the fluid to a temperature in a specified temperature range and provide the fluid to a solid oxide electrolysis system (4803) that converts water to hydrogen. 451. The system of claim 450, wherein the fluid comprises a mixture of oxygen and nitrogen. 452. The system of claim 450, wherein the fluid has a volume percentage of oxygen that is above 25% and below 60%. 453. The system of claim 450, wherein a volume percentage of hydrogen in a product fluid produced by electrolysis is greater than a volume percentage of hydrogen in the water provided to the solid oxide cells. 454. The system of claim 450, wherein the specified temperature range is 800° C. to 900° C. 455. The system of claim 450, wherein the fluid has a flow rate of at least 1500 kg/hr. 456. The system of claim 450, wherein the fluid has a flow rate between 1500 kg/hr and 2000 kg/hr. 457. The system of claim 450, wherein the fluid provides an amount of heat sufficient to maintain electrolysis of water in the solid oxide cells. Method Providing Heated Fluid for Electrolysis, the Heat being Provided from a High-Efficiency TES System and Used to Increase Efficiency of Electrolysis Reaction. 458. A method, comprising:heating a storage medium using heating elements that convert electricity from a renewable energy source (4903) into heat;circulating a fluid through the storage medium to heat the fluid to a temperature in a specified temperature range; andproviding the fluid to a solid oxide electrolysis system (4803) that converts water to hydrogen. 459. The method of claim 458, wherein the fluid comprises a mixture of oxygen and nitrogen. 460. The method of claim 458, wherein the fluid has a volume percentage of oxygen that is above 25% and below 60%. 461. The method of claim 458, wherein the specified temperature range is 800° C. to 900° C. 462. The method of claim 458, wherein the fluid has a flow rate of at least 1500 kg/hr. 463. The method of claim 458, wherein the fluid has a flow rate between 1500 kg/hr and 2000 kg/hr. 464. The method of claim 458, wherein the fluid provides an amount of heat sufficient to maintain electrolysis of water in the solid oxide cells. 465. The method of claim 458, further comprising receiving at least some oxygen enriched fluid from solid oxide cells in the thermal energy storage system, the method further comprising:implementing the oxygen enriched fluid in continued operation of the thermal energy storage system; orimplementing the oxygen enriched fluid in the conversion of the input electricity to stored thermal energy. System Providing Heated Fluid for Electrolysis, the Heat being Provided from a High-Efficiency TES System and Used to Increase Efficiency of Electrolysis Reaction. 466. A thermal energy storage (TES) system (5001), comprising:a storage medium configured to store thermal energy;a heating element configured to heat the storage medium using electricity from a renewable energy source (4903); anda fluid movement system (213,4223) configured to move a fluid through the storage medium to heat the fluid to a temperature in a specified temperature range and provide the fluid to a solid oxide fuel cell system (5007) that generates electricity and water from hydrogen. 467. The system of claim 466, wherein the fluid comprises a mixture of oxygen and nitrogen. 468. The system of claim 466, wherein the fluid has a volume percentage of oxygen that is above 25% and below 60%. 469. The system of claim 466, wherein the specified temperature range is 600° C. and 700° C. 470. The system of claim 466, wherein the fluid has a flow rate of at least 1500 kg/hr. 471. The system of claim 466, wherein the fluid has a flow rate between 1500 kg/hr and 2000 kg/hr. 472. The system of claim 466, wherein the fluid is configured to maintain a temperature of the solid oxide cells. 473. The system of claim 466, wherein at least a portion of the fluid that sweeps through the solid oxide cells is recirculated to the storage medium. Method Using Stored Thermal Energy in a Fuel Cell System to Convert Hydrogen to Electricity and Water. 474. A method, comprising:heating a storage medium using heating elements that convert electricity from a renewable energy source (4903) into heat;circulating a fluid through the storage medium to heat the fluid to a temperature in a specified temperature range; andproviding the fluid to a solid oxide fuel cell system (5007) that generates electricity and water from hydrogen. 475. The method of claim 474, wherein the fluid comprises a mixture of oxygen and nitrogen. 476. The method of claim 474, wherein the fluid has a volume percentage of oxygen that is above 25% and below 60%. 477. The method of claim 474, wherein the specified temperature range is 600° C. and 700° C. 478. The method of claim 474, wherein the fluid has a flow rate of at least 1500 kg/hr. 479. The method of claim 474, wherein the fluid has a flow rate between 1500 kg/hr and 2000 kg/hr. 480. The method of claim 474, wherein the fluid removes heat from the solid oxide cells. 481. The method of claim 474, further comprising providing at least a portion of the fluid that sweeps through the solid oxide cells to the storage medium. Electrolysis System Providing Heated Fluid for Electrolysis, the Heat being Provided from a High-Efficiency TES System and Used to Increase Efficiency of Electrolysis Reaction. 482. An electrolysis system, comprising:a plurality of solid oxide cells (4803) configured to electrolyze water to produce hydrogen when an electric potential is provided to the solid oxide cells; anda sweep path across the solid oxide cells (4803), wherein the sweep path is configured to circulate a fluid received from a thermal energy storage system (4801), wherein the fluid is heated by circulating the fluid through a storage medium storing thermal energy generated by conversion of input electricity from a renewable energy source, and wherein the fluid is heated to a temperature in a specified temperature range. 483. The system of claim 482, wherein the fluid comprises a mixture of oxygen and nitrogen. 484. The system of claim 482, wherein the fluid has a volume percentage of oxygen that is above 25% and below 60%. 485. The system of claim 482, wherein a volume percentage of hydrogen in a product fluid produced by electrolysis is greater than a volume percentage of hydrogen in the water provided to the solid oxide cells. 486. The system of claim 482, wherein the water provided to the solid oxide cells comprises water and hydrogen. 487. The system of claim 482, wherein the water comprises at least 90% water. 488. The system of claim 482, wherein the specified temperature range is 800° C. to 900° C. 489. The system of claim 482, wherein the water is at a temperature below the temperature of the fluid but above 800° C. 490. The system of claim 482, wherein the fluid has a flow rate of at least 1500 kg/hr. 491. The system of claim 482, wherein the fluid has a flow rate between 1500 kg/hr and 2000 kg/hr. 492. The system of claim 482, wherein hydrogen produced by electrolysis is at a temperature above a temperature of the water. 493. The system of claim 482, wherein the electric potential provided to the solid oxide cells is between 1 volt and 3 volts. 494. The system of claim 482, wherein the fluid provides an amount of heat sufficient to maintain electrolysis of water in the solid oxide cells. 495. The system of claim 482, further comprising a steam generator (4805) configured to condense the hydrogen and generate steam by exchanging heat from the hydrogen with water. 496. The system of claim 495, wherein at least some of the steam generated by the steam generator is configured to be recirculated to the solid oxide cells. 497. The system of claim 496, wherein the recirculated fluid includes at least some hydrogen gas. 498. The system of claim 495, wherein at least some of the condensed hydrogen is configured to be stored. 499. The system of claim 482, wherein the fluid is enriched with at least some of oxygen produced by the electrolysis of water in the solid oxide cells. 500. The system of claim 499, wherein the oxygen enriched fluid has a volume percentage of oxygen above the volume percentage of oxygen in the fluid. 501. The system of claim 499, wherein a temperature of the hydrogen is near a temperature of the oxygen enriched fluid. 502. The system of claim 499, wherein the oxygen enriched fluid includes oxygen and nitrogen. 503. The system of claim 499, wherein a temperature of the oxygen enriched fluid is between a temperature of the water and a temperature of the fluid. 504. The system of claim 499, wherein the oxygen enriched fluid is provided to the thermal energy storage system (4801). 505. The system of claim 499, further comprising a steam generator (4807) configured to generate steam by exchanging heat from the oxygen enriched fluid with water. 506. The system of claim 482, wherein the water comprises water and carbon dioxide. 507. The system of claim 506, wherein the water and carbon dioxide are configured to be converted to carbon monoxide and hydrogen by electrolysis in the solid oxide cells. 508. The system of claim 506, further comprising a syngas conversion system (4109) configured to produce a synthetic hydrocarbon fluid from the produced hydrogen and carbon monoxide. Electrolysis Method Providing Heated Fluid for Electrolysis, the Heat being Provided from a High-Efficiency TES System and Used to Increase Efficiency of Electrolysis Reaction. 509. A method of electrolysis, comprising:circulating a fluid across a plurality of solid oxide cells (4803), wherein the fluid has been heated by a storage medium storing thermal energy generated by conversion of input electricity from a renewable energy source (4903);providing water to the solid oxide cells (4803); andproviding an electric potential to the solid oxide cells (4803) to electrolyze the water and generate hydrogen. 510. The method of claim 509, wherein the fluid comprises a mixture of oxygen and nitrogen. 511. The method of claim 509, wherein the fluid has a volume percentage of oxygen that is above 25% and below 60%. 512. The method of claim 509, wherein a volume percentage of hydrogen in a product fluid produced by electrolysis is greater than a volume percentage of hydrogen in the water provided to the solid oxide cells. 513. The method of claim 509, wherein the water provided to the solid oxide cells comprises water and hydrogen. 514. The method of claim 509, wherein the water comprises at least 90% water. 515. The method of claim 509, wherein the specified temperature range is 800° C. to 900° C. 516. The method of claim 509, wherein the water is at a temperature below the temperature of the fluid but above 800° C. 517. The method of claim 509, wherein the fluid has a flow rate of at least 1500 kg/hr. 518. The method of claim 509, wherein the fluid has a flow rate between 1500 kg/hr and 2000 kg/hr. 519. The method of claim 509, wherein hydrogen produced by electrolysis is at a temperature above a temperature of the water. 520. The method of claim 509, wherein the electric potential provided to the solid oxide cells is between 1 volt and 3 volts. 521. The method of claim 509, wherein the fluid provides an amount of heat sufficient to maintain electrolysis of water in the solid oxide cells. 522. The method of claim 509, further comprising providing the hydrogen to a steam generator (4805) to condense the hydrogen and generate steam by exchanging heat from the hydrogen with water. 523. The method of claim 522, further comprising adding a recirculated fluid to the water provided to the solid oxide cells, wherein the recirculated fluid includes at least some of the steam generated by the steam generator. 524. The method of claim 523, wherein the recirculated fluid includes at least some hydrogen gas. 525. The method of claim 522, further comprising storing at least some of the condensed hydrogen. 526. The method of claim 509, wherein the electrolysis of water produces oxygen, and wherein the fluid is enriched with at least some of the produced oxygen. 527. The method of claim 526, wherein the oxygen enriched fluid has a volume percentage of oxygen above the volume percentage of oxygen in the fluid. 528. The method of claim 526, wherein a temperature of the hydrogen is near a temperature of the oxygen enriched fluid. 529. The method of claim 526, wherein the oxygen enriched fluid includes oxygen and nitrogen. 530. The method of claim 526, wherein a temperature of the oxygen enriched fluid is between a temperature of the water and a temperature of the fluid. 531. The method of claim 526, further comprising providing the oxygen enriched fluid to a thermal energy storage system (4801), and:implementing the oxygen enriched fluid in continued operation of the thermal energy storage system; orimplementing the oxygen enriched fluid in the conversion of the input electricity to stored thermal energy. 532. The method of claim 526, further comprising providing the oxygen enriched fluid to a steam generator (4807) to generate steam by exchanging heat from the oxygen enriched fluid with water. 533. The method of claim 509, wherein the water provided to the solid oxide cells comprises water and carbon dioxide. 534. The method of claim 533, wherein the water and carbon dioxide are converted to carbon monoxide and hydrogen by electrolysis in the solid oxide cells. 535. The method of claim 534, further comprising providing the hydrogen and carbon monoxide to a syngas conversion system (4109) to produce a synthetic hydrocarbon fluid. System Providing Heated Fluid for Electrolysis, the Heat being Provided from a High-Efficiency TES System and Used to Increase Efficiency of Electrolysis Reaction. 536. A fuel cell system comprising:a plurality of solid oxide cells (5007) configured to generate electricity and hydrogen from water; anda sweep path across the solid oxide cells (5007), wherein the sweep path is configured to circulate a fluid received from a thermal energy storage system (5001), wherein the fluid is heated by circulating the fluid through a storage medium storing thermal energy generated by conversion of input electricity from a renewable energy source (4903), and wherein the fluid is heated to a temperature in a specified temperature range. 537. The system of claim 536, wherein the fluid comprises a mixture of oxygen and nitrogen. 538. The system of claim 536, wherein the fluid has a volume percentage of oxygen that is above 25% and below 60%. 539. The system of claim 536, wherein the specified temperature range is 600° C. and 700° C. 540. The system of claim 536, wherein the fluid has a flow rate of at least 1500 kg/hr. 541. The system of claim 536, wherein the fluid has a flow rate between 1500 kg/hr and 2000 kg/hr. 542. The system of claim 536, further comprising a heat exchanger (5013) configured to heat hydrogen fed to the solid oxide cells with the fluid. 543. The system of claim 536, wherein the hydrogen provided to the solid oxide cells includes at least some steam. 544. The system of claim 536, wherein the fluid is configured to maintain a temperature of the solid oxide cells. 545. The system of claim 536, wherein the electricity generated is direct current electricity. 546. The system of claim 536, wherein at least a portion of the residual hydrogen from the solid oxide cells is configured to be recirculated to the solid oxide cells. 547. The system of claim 536, wherein at least a portion of the fluid that sweeps through the solid oxide cells is provided to the storage medium. Method Providing Heated Fluid for Electrolysis, the Heat being Provided from a High-Efficiency TES System and Used to Increase Efficiency of Electrolysis Reaction. 548. A method, comprising:circulating a fluid across a plurality of solid oxide cells (5007), wherein the fluid has been heated by a storage medium storing thermal energy generated by conversion of input electricity from a renewable energy source (4903);providing hydrogen to the solid oxide cells (5007); andgenerating electricity and water from the solid oxide cells (5007). 549. The method of claim 548, wherein the fluid comprises a mixture of oxygen and nitrogen. 550. The method of claim 548, wherein the fluid has a volume percentage of oxygen that is above 25% and below 60%. 551. The method of claim 548, wherein the specified temperature range is 600° C. and 700° C. 552. The method of claim 548, wherein the fluid has a flow rate of at least 1500 kg/hr. 553. The method of claim 548, wherein the fluid has a flow rate between 1500 kg/hr and 2000 kg/hr. 554. The method of claim 548, further comprising heating hydrogen fed to the solid oxide cells with the fluid in a heat exchanger (5013). 555. The method of claim 548, further comprising adding steam to the hydrogen provided to the solid oxide cells. 556. The method of claim 548, wherein the fluid removes heat from the solid oxide cells. 557. The method of claim 548, wherein the electricity generated is direct current electricity. 558. The method of claim 548, further comprising recirculating at least a portion of the residual hydrogen produced from the solid oxide cells to the solid oxide cells. 559. The method of claim 548, further comprising providing at least a portion of the fluid that sweeps through the solid oxide cells to the storage medium. Apparatus for Cogeneration Using Heat from Solid Oxide Electrolyzes to Generate Steam and Reducing Waste of Energy. 560. An apparatus comprising:a thermal storage assemblage (4100) including a plurality of thermal storage blocks, wherein at least some of the thermal storage blocks include multiple fluid flow slots, wherein at least some of the fluid flow slots are configured to define fluid pathways through the thermal storage blocks;a plurality of heater elements (3607) positioned within the thermal storage assemblage, wherein each of the plurality of heater elements is configured to heat at least one of the thermal storage blocks;a fluid movement system (213,4223) configured to direct a stream of fluid through the fluid pathways to heat the fluid to a specified temperature range, wherein the fluid movement device is configured to provide the heated fluid in the specified temperature range to a solid oxide electrolysis system configured to extract hydrogen from water and output the heated fluid at a lower temperature; anda steam generator configured to receive the lower-temperature fluid from the electrolysis system convert input feed water into steam. 561. The apparatus of claim 560, wherein the steam generator is a once-through steam generator. 562. The apparatus of claim 560, wherein the steam generator is a heat recovery steam generator. 563. The apparatus of claim 560, wherein the steam generator includes a plurality of conduits coupled to receive the input feed water, wherein selected ones of the conduits are arranged to mitigate scale formation and overheating. 564. The apparatus of claim 563, wherein ones of the plurality of conduits are arranged in the steam generator transversely to a path of flow of the lower temperature fluid. 565. The apparatus of claim 560, wherein the thermal storage assembly comprises:an enclosure containing the plurality of thermal storage blocks; anda thermal barrier separating a first subset of the plurality of thermal storage blocks from a second subset of the plurality of thermal storage blocks. 566. The apparatus of claim 565, wherein the fluid movement system is configured to direct the stream of fluid through the fluid pathways of one of the first and second subsets of thermal concurrent with an electricity source adding heat to another one of the first and second sub set. 567. The apparatus of claim 560, wherein the fluid comprises oxygen and nitrogen. 568. The apparatus of claim 560, wherein the thermal storage assemblage is configured to store thermal energy generated by a conversion of input electricity from an first input energy supply, the first input energy supply having intermittent availability. 569. The apparatus of claim 568, wherein the thermal storage assemblage is further configured to store thermal energy generated by a conversion of input electricity from an second input energy supply configured to provide electricity on demand. Apparatus for Cogeneration to Use Steam Output from a Steam Turbine in an Industrial Process, Reducing Waste of Energy. 570. An apparatus comprising:a thermal storage assemblage (4100) including a plurality of thermal storage blocks, wherein at least some of the thermal storage blocks include multiple fluid flow slots, wherein at least some of the fluid flow slots are configured to define fluid pathways through the thermal storage blocks;a plurality of heater elements (3607) positioned within the thermal storage assemblage, wherein each of the plurality of heater elements is configured to heat at least one of the thermal storage blocks;a fluid movement system (213,4223) configured to direct a stream of fluid through the fluid pathways to heat the fluid to a specified temperature range;a steam generator configured to receive the fluid to convert input feed water into input steam having a first pressure;a steam turbine configured to receive the input steam and provide output steam at a second pressure that is less than the first pressure; anda second fluid movement device configured to move the output steam for use in an industrial process. 571. The apparatus of claim 570, wherein the steam generator is a superheat boiler. 572. The apparatus of claim 570, wherein the steam generator includes a plurality of conduits coupled to receive the input feed water, wherein selected ones of the conduits are arranged to mitigate scale formation and overheating. 573. The apparatus of claim 572, wherein ones of the plurality of conduits are arranged in the steam generator transversely to a path of flow of the lower temperature fluid. 574. The apparatus of claim 570, wherein the industrial process comprises producing petroleum-based fuels. 575. The apparatus of claim 570, wherein the industrial process comprises producing biofuels. 576. The apparatus of claim 570, wherein the industrial process comprises producing diesel fuels. 577. The apparatus of claim 570, wherein the industrial process comprises drying grains. 578. The apparatus of claim 570, wherein the steam turbine is configured to cause an electrical generator to provide electricity to the industrial process. Apparatus Providing Heat from Thermal Storage Assemblage to Generate Steam for a Turbine with Turbine Waste Heat being Used to Preheat Feed Water for a High-Pressure Once-Through Steam Generator. 579. An apparatus comprising:a thermal storage assemblage (4100) including a plurality of thermal storage blocks, wherein at least some of the thermal storage blocks include multiple fluid flow slots, wherein at least some of the fluid flow slots are configured to define fluid pathways through the thermal storage blocks;a plurality of heater elements (3607) positioned within the thermal storage assemblage, wherein each of the plurality of heater elements is configured to heat at least one of the thermal storage blocks;a fluid movement system (213,4223) configured to direct a stream of a first fluid through the fluid pathways to heat the first fluid to a specified temperature range;a first steam generator configured to, using the first fluid, convert input feed water into steam;a steam turbine configured to cause generation of electricity using the steam; anda preheater configured to, using waste heat from the steam turbine, preheat feed water provided to a second steam generator. 580. The apparatus of claim 579, wherein the first steam generator is a heat recovery steam generator. 581. The apparatus of claim 579, wherein the second steam generator is a once-through steam generator. 582. The apparatus of claim 579, further comprising a condenser coupled to the steam turbine, wherein the condenser is configured to condense steam received from the steam turbine into water. 583. The apparatus of claim 582, further comprising a recirculation pump configured to provide, as feed water to the first steam generator, water produced by the condenser. 584. The apparatus of claim 579, wherein the second steam generator is configured to generate steam using a second fluid from a second storage medium configured to store thermal energy. 585. The apparatus of claim 579, wherein the preheater is configured to output a third fluid to the thermal storage assemblage. Apparatus Using Heat from Thermal Storage Assemblage to Generate Steam with Feedback to Maintain Steam Quality. 586. An apparatus comprising:a thermal storage assemblage (4100) including a plurality of thermal storage blocks, wherein at least some of the thermal storage blocks include multiple fluid flow slots, wherein at least some of the fluid flow slots are configured to define fluid pathways through the thermal storage blocks;a plurality of heater elements (3607) positioned within the thermal storage assemblage, wherein each of the plurality of heater elements is configured to heat at least one of the thermal storage blocks;a fluid movement system (213,4223) configured to direct a stream of fluid through the fluid pathways to heat the fluid to a specified temperature range;a steam generator configured to receive the fluid to convert input feed water into input steam;a measurement unit configured to determine a measured steam quality value of steam output from the steam generator; anda controller configured to cause the cause the fluid movement system to direct the stream of fluid, and further configured to use the measured steam quality as feedback to adjust a flow rate of the fluid to maintain the measured steam quality within a specified steam quality range. 587. The apparatus of claim 586, wherein the measurement unit includes a separator configured to separate steam output from the steam generator from water vapor output from the steam generator, wherein the measurement unit is configured to determine the measured steam quality based on fraction of the water vapor output from the steam generator relative to the steam output from the steam generator. 588. The apparatus of claim 586, wherein the measurement unit is configured to determine the steam quality based on a flow velocity of steam output from the steam generator and a mass flow rate of the input feed water. 589. The apparatus of claim 586, wherein the steam generator is a once-through steam generator. 590. The apparatus of claim 586, wherein the controller is configured to cause delivery of steam in accordance within a specified range of steam delivery rates. 591. The apparatus of claim 590, wherein the controller is configured to specify the range of steam delivery rates based on forecast information. 592. The apparatus of claim 591, wherein the forecast information includes weather forecast information. 593. The apparatus of claim 591, wherein the forecast information includes expected electricity rates. 594. The apparatus of claim 591, wherein the forecast information includes expected steam demand. Cogeneration System Using Heat from Electrolysis Process to Generate Steam Input to a Once-Through Steam Generator. 595. A system comprising:a storage medium configured to store thermal energy generated by a conversion of input electricity from an input energy supply, the input energy supply having intermittent availability;a fluid movement device configured to move fluid through the storage medium to heat the fluid to a specified temperature, the fluid comprising oxygen and nitrogen, wherein the fluid movement device is configured to provide the fluid at the specified temperature to a solid oxide cell electrolysis system that converts water to hydrogen and enriches the fluid with oxygen; anda once-through steam generator configured to, using the fluid received from the electrolysis system convert input feed water into steam. 596. The system of claim 595, further comprising a steam turbine configured to cause an electrical generator to generate of electricity using steam received from the steam generator. 597. The system of claim 595, wherein the thermal storage unit comprises a plurality of bricks. 598. The system of claim 595, further comprising a controller configured to cause the fluid movement device to move fluid at a particular rate. 599. The system of claim 598, further comprising a measurement unit configured to measure a parameter of steam output from the steam generator. 600. The system of claim 598, wherein the controller is configured to adjust the particular rate based on the measurement of the parameter of steam output. 601. The system of claim 598, wherein the measurement unit comprises a separator configured to measure a quality of the steam output from the steam generator by separating the steam into a liquid phase and a vapor phase. 602. The system of claim 598, wherein the measurement unit is configured to measure a velocity of steam output from the steam generator. 603. The system of claim 598, wherein the controller is configured to control an amount of fluid moved through the storage medium based on a weather forecast. 604. The system of claim 598, wherein the controller is configured to control and amount of fluid moved through the storage medium based on an expected difference in electricity costs on a first day and a second day. 605. The system of claim 595, wherein the intermittent energy supply comprises a thermophotovoltaic generation system configured to convert thermal radiation into electrical energy. 606. The system of claim 595, wherein the intermittent energy supply comprises a wind turbine configured to generate electricity. 607. The system of claim 595, wherein the intermittent energy supply comprises a solar energy source configured to convert solar energy into electricity. 608. The system of claim 595, wherein the fluid movement device comprises a closed fluid recirculation loop. 609. The system of claim 595, further comprising a pump, and wherein the pump is configured to force the input feed water through one or more conduits of the steam generator. 610. The system of claim 609, wherein the one or more conduits mounted in the steam generator transversely to a path fluid flow. System for Cogeneration Using Steam Output from a Steam Turbine in an Industrial Process, Reducing Waste of Energy. 611. A system comprising:a storage medium configured to store thermal energy generated by a conversion of input electricity from an input energy supply, the first input energy supply having intermittent availability;a first fluid movement device configured to move fluid through the storage medium to heat the fluid to a specified temperature;a once-through steam generator configured to, using the fluid, convert input feed water into an input steam having a first pressure;a steam turbine configured to provide an output steam at a second pressure that is less than the first pressure; anda second fluid movement device configured to move the output steam for use in an industrial process. 612. The system of claim 611, wherein the steam turbine is configured to cause generation of electricity by an electrical generator. 613. The system of claim 612, wherein the electrical generator is configured to provide electricity to a power grid. 614. The system of claim 611, wherein the industrial process comprises production of biofuels. 615. The system of claim 611, wherein the industrial process comprises production of petroleum-based fuels. 616. The system of claim 611, wherein the industrial process comprises production of diesel fuels. 617. The system of claim 611, wherein industrial process comprises drying of grains. 618. The system of claim 611, further comprising a controller configured to cause the steam generator to generate steam at a specified steam quality based on steam quality. 619. The system of claim 618, further comprising a measurement unit configured to determine the steam quality based on separation of steam and water vapor output from the steam generator. 620. The system of claim 618, further comprising a measurement unit configured to determine the steam quality based on measurements of steam outlet flow and feed water input flow. 621. The system of claim 618, wherein the controller is configured to control a rate at which fluid is moved through the storage device by the first fluid movement device. 622. The system of claim 611, wherein the storage medium comprises a plurality of bricks. System for Cogeneration Using Steam Output from a Steam Turbine is Input to a Steam Generator, Reducing Waste of Energy. 623. A system comprising:a first storage medium configured to store thermal energy generated by a conversion of input electricity from an input energy supply, the input energy supply having intermittent availability;a fluid movement device configured to move fluid through the storage medium to heat the fluid to a specified temperature;a first steam generator configured to, using the fluid, convert first input feed water into steam;a steam turbine configured to, using the steam, cause an electrical generator to generate electricity; anda preheater configured to, using waste heat from the steam turbine, preheat second feed water provided to a second steam generator. 624. The system of claim 623, wherein the second steam generator is a once-through steam generator. 625. The system of claim 623, further comprising a condenser configured to receive at least a portion of the steam from the steam turbine and configured to condense the portion of steam into third feed water. 626. The system of claim 625, further comprising a recirculation pump configured to provide the third feed water to the first steam generator. 627. The system of claim 623, wherein the steam generator is a heat recovery steam generator. 628. The system of claim 623, further comprising:a measurement unit configured to determine a measured output steam quality; anda controller configured to adjust a current output steam quality to within a specified range using the measured output steam quality as feedback. 629. The system of claim 628, wherein the controller is configured to cause fluid movement device to adjust a rate of fluid flow through the storage medium in accordance with the feedback and the specified range of steam quality. Method for Optimizing Use of Available VRE. 630. A method for controlling the distribution of electrical power derived from a renewable energy source received at a power management facility, including the steps of:determining a first demand for a first use of the power, and providing a first portion of the power to the first use;determining a second demand for a second use of the power and, if a first excess amount of power is available once the first portion has been provided to the first use sufficient to meet the first demand, providing a second portion of the first excess amount of power to the second use; andif a second excess amount of power is available once the second portion has been provided to the second use sufficient to meet the second demand, providing the second excess amount of power to a third use. 631. The method of claim 630, wherein:the first use is electrical demand of an industrial facility; andthe second use is an electrolysis process for producing hydrogen. 632. The method of claim 630, wherein the third use includes providing at least a portion of the second excess amount of power to a thermal charging apparatus of a thermal storage unit. 633. The method of claim 630, wherein the third use includes providing at least a portion of the second excess amount of power to an electrical power grid. 634. The method of claim 630, wherein the third use includes providing at least a portion of the second excess amount of power to a thermal charging apparatus of a thermal storage unit. 635. The method of claim 630, wherein the third use includes providing at least a portion of the second excess amount of power to a thermal charging apparatus of a thermal storage unit, and further including the steps of:determining whether the thermal storage unit has been fully charged, and if so, providing a remaining portion of the second excess amount of power to an electrical power grid. Configurations of TES System Components. 636. A system for thermal energy storage and delivery, comprising:a thermal storage assemblage including a plurality of thermal storage blocks, wherein at least some of the thermal storage blocks include multiple radiation cavities and multiple fluid flow slots, wherein some of the radiation cavities and some of the fluid flow slots are configured to define fluid pathways through the thermal storage blocks;a plurality of heater elements positioned within the thermal storage assemblage and adjacent to at least some of the radiation cavities, wherein each of the plurality of heater elements is configured to heat at least one of the thermal storage blocks via energy radiated into multiple ones of the radiation cavities and onto surfaces that bound the respective radiation cavities; anda fluid movement system configured to direct a stream of fluid through the fluid pathways;with any one or more of the following components or characteristics:(a) the heater element pathway includes one or more slots configured to hang a heater element;(b) the thermal storage blocks include shelf portions that interlock when the thermal storage blocks are positioned in a stack;(c) the thermal storage blocks include multiple substantially rectangular portions that each include multiple openings to other tiers and that bound different cavities of one or more tiers;(d) one or more stacks of thermal storage blocks in the TSU are positioned using space elements;(e) the thermal storage blocks of the first and second tiers are stacked without spacing between tiers; and(f) at least half of a surface of at least a portion of a particular thermal storage block thermal storage material is not an opening, i.e. there relatively small slits through the brick, compared to the size of the radiation cavity. Carbon Capture 637. A system that includes:a carbon dioxide capture system configured to separate carbon dioxide from exhaust gases;a thermal storage system configured to convert input electricity from an input energy supply to stored thermal energy, the input energy supply having intermittent availability; anda power generation system configured to:convert a portion of the stored thermal energy to output electricity via a turbine; andprovide the output electricity and turbine waste heat to the carbon dioxide capture system;wherein the carbon dioxide capture system is configured to operate using the provided electricity and heat. 638. The system of claim 637, wherein the thermal storage system includes:a heating element configured to heat a storage medium using the input electricity from the input energy supply; anda blower configured to circulate fluid through the heated storage medium. 639. The system of claim 637 or 638, wherein the power generation system includes:a heat exchanger configured to generate steam using circulated fluid; anda steam turbine configured to generate the supplied electricity from the produced steam. 640. The system of any one of claims 637 to 639, wherein the carbon dioxide capture system is configured to use a portion of stored thermal energy as heat to separate the carbon dioxide from the exhaust gases. 641. The system of any one of claims 637 to 640, wherein the thermal energy storage system is further configured to generate the output electricity in a substantially continuous manner. 642. A method that includes:converting, by a thermal energy storage system, input electricity from an intermittently availability energy supply to stored thermal energy;converting, by the thermal energy storage system and a turbine, the stored thermal energy to output electricity; andproviding, by the thermal energy storage system, the output electricity to a carbon dioxide capture system that separates carbon dioxide from exhaust gases, wherein the output electricity is provided at least at times when the energy supply is not available. 643. A method that includes:receiving, by a carbon dioxide capture system, exhaust gases from combustion of a fuel source;receiving, by the carbon dioxide capture system, electricity and heat generated from a thermal energy storage system and turbine, wherein the thermal energy storage system stores thermal energy using an intermittently availability energy supply; andseparating, by the carbon dioxide capture system, carbon dioxide from exhaust gases using the received electricity and heat, wherein the separating is performed at least at times in which the energy supply is not available. | 694,285 |
11859519 | DETAILED DESCRIPTION Heavy duty (HD) diesel engines require high braking power, in particular at low engine speed. Some HD diesel engines are configured with valvetrains having a valve bridge and include with single overhead cam (SOHO) and overhead valve (OHV) valvetrain. The present disclosure provides high braking power without applying high load on the rest of the valvetrain (particularly the pushrod and camshaft). In this regard, the present disclosure provides a configuration that opens only one exhaust valve during a braking event. With initial reference toFIG.1, a partial valvetrain assembly constructed in accordance to one example of the present disclosure is shown and generally identified at reference10. The partial valve train assembly10utilizes engine braking and is shown configured for use in a six-cylinder engine. It will be appreciated however that the present teachings are not so limited. In this regard, the present disclosure may be used in any valve train assembly that utilizes engine braking. The partial valve train assembly10is supported in a valve train carrier11and can include two or more rocker arm assemblies per cylinder. In the example embodiment, each cylinder includes an intake valve rocker arm assembly (not shown), an exhaust valve rocker arm assembly12, and an engine brake rocker arm assembly13. The intake valve rocker arm assembly is configured to control motion of intake valves of an associated engine (not shown). In the example embodiment, the exhaust valve rocker arm assembly12is configured to control opening of exhaust valves of the engine, and engine brake rocker arm assembly13incorporates integrated engine brake functionality. In general, the exhaust valve rocker arm assembly12is configured to control exhaust valve motion in a combustion engine drive mode, and the engine brake rocker arm assembly13is configured to act on one of the two exhaust valves in an engine brake mode, as will be described herein in more detail. In the illustrated embodiment, the exhaust valve rocker arm assembly12can generally include an exhaust rocker arm14that rotates about a rocker shaft16and selectively engages a valve bridge18. The engine brake rocker arm assembly13can generally include a brake rocker arm20having an engine brake capsule assembly22. In the example embodiment, the valve bridge18is configured to engage first and second exhaust valves24,26associated with a cylinder of the engine. In the illustrated example, the first exhaust valve24is a non-braking exhaust valve that is biased by a valve spring28, and the second exhaust valve26is a braking exhaust valve that is biased by a valve spring30. The exhaust rocker arm14rotates around the rocker shaft16based on a lift profile32of a cam shaft34, as described herein in more detail, and a pass through pin36is positioned on the valve bridge18to enable actuation of exhaust valve26without actuation of valve bridge18or first exhaust valve24. In the illustrated example, exhaust rocker arm14includes an end having a bore40, a mechanical lash adjusting shaft42, an e-foot48, and a nut50. The shaft42includes a first end52and an opposite second end54and extends through bore40. The e-foot48is coupled to or operably associated with the shaft first end52, and the nut50is threadably secured to the shaft second end54. The valve lash set at a central contact point of the bridge18may be adjusted by way of shaft42and nut50. In this regard, the nut50can be adjusted (e.g., rotated) to provide a desired lash setting between the e-foot48and the valve bridge18. Other configurations may be used. With additional reference toFIG.2, in the example embodiment, the engine brake capsule assembly22is operably associated with an actuator assembly60. As will become appreciated from the following discussion, the actuator assembly60is hydraulically controlled between a first position (FIG.2B) and a second position (FIG.2C) to mechanically move the engine brake capsule assembly22between a respective latched or locked position and an unlatched or unlocked position. Notably, the actuator assembly60fluidly segregates the engine brake capsule assembly22from a source of hydraulic fluid. The intermediate placement of the hydraulic actuator assembly60between the selectively lockable engine brake capsule assembly22and the source of hydraulic fluid eliminates limitations associated with a fully mechanical actuator. With continued reference toFIGS.1and2, in the illustrated example, the engine brake capsule assembly22is at least partially disposed within a bore62formed in the brake rocker arm20and generally includes a mechanical lash adjuster assembly64, a first castellation member70, a second castellation member72, and a castellation biasing member74. An anti-rotation mechanism76(FIG.2) such as a screw extends at least partially through the rocker arm14and is configured to facilitate preventing rotation of the engine brake capsule assembly22within the bore62. The mechanical lash adjuster assembly64generally includes a castellation shaft80, a lash adjustment screw82, a retainer84, an e-foot86, a castellation nut88, and a stop screw and washer90. The castellation shaft80includes a first end92and an opposite second end94and extends through the lash adjustment screw82and the retainer84, which are disposed at least partially within the rocker arm bore62. Moreover, the castellation shaft80can be configured to slide within lash adjustment screw82. The e-foot86is coupled to or operably associated with the castellation shaft first end92, and stop screw and washer90can be threadably secured to an inner bore formed in the castellation shaft second end94. The castellation nut88is threadably secured to the lash adjustment screw82. The valve lash set at a contact point of the bridge18may be adjusted by way of lash adjustment screw82and castellation nut88. As shown inFIG.2, in the example embodiment, the first castellation member70can be a cup-like castellated capsule body having a series of first teeth100and first valleys102, and the second castellation member72can be a cup-like castellated capsule body having a series of second teeth104and second valleys106. As described herein in more detail, the castellation members70,72can be positioned in the locked position (FIG.2B) where the first and second teeth100,104engage each other, or in the unlocked position (FIG.2C) where the first and second teeth100,104are respectively received within the second and first valleys106,102. As shown inFIG.1, the castellation biasing member74can be disposed between the second castellation member72and the first castellation member70and is configured to bias the first and second castellation members70,72apart from each other. With additional reference toFIGS.3-5, the actuator assembly60will be described in more detail. The actuator assembly60is configured to rotate the first castellation member70relative to the second castellation member72to switch the engine brake capsule assembly22between the brake active, locked position (FIG.2B) and the brake inactive, unlocked position (FIG.2C). In the example embodiment, the actuator assembly60generally includes a plunger or actuator pin110, a retainer112, and a pin return mechanism114(e.g., a spring). While the actuator pin110is described herein as hydraulically actuated, it will be appreciated that actuator pin110may be actuated by other means such as, for example, electric, pneumatic, and/or electromagnetic. As shown inFIG.5, the actuator pin110is configured to translate within a chamber or bore116formed in the rocker arm20and generally includes a first end118, an opposite second end120, a first seal122, a second seal124, and an annular flange126. The first end118includes the first seal122and at least partially defines a hydraulic chamber128adjacent to the actuator pin110that defines a portion of the bore116. The hydraulic chamber128can be fluidly coupled to a source of hydraulic fluid, for example, via a fluid port130formed in the brake rocker arm20. The second end120is received within retainer112and includes the second seal124. The pin return mechanism114is disposed at least partially within a seat132formed in the retainer112and is configured to bias the actuator pin110into the unlocked position (FIG.2C). In the example embodiment, the annular flange126is received within a slot134formed in the first castellation member70. However, it will be appreciated that in alternative arrangements, the annular flange126can be received within a slot formed in the second castellation member72. In the example shown, the actuator pin110can actuate as a result of high pressure fluid entering the hydraulic chamber128behind the actuator pin110, thereby translating actuator pin110within bore116. This causes rotational movement of the first castellation member70, as described herein in more detail. In some examples, the fluid can be pressurized engine oil or other hydraulic fluid. As discussed, the engine brake capsule assembly22is movable between the brake inactive (unlocked) position and the brake active (locked) position by the actuator assembly60. In the unlocked, brake inactive position (FIG.2C), the second teeth104of second castellation member72are aligned with the first valleys102of the first castellation member70, and the first teeth100of the first castellation member70are aligned with the second valleys106of the second castellation member72such that the second castellation member72slides inside the first castellation member70and the engine brake capsule assembly22collapses. In the locked, brake active position (FIG.2B), the actuator assembly60rotates the first castellation member70relative to the second castellation member72so the first and second teeth100,104are aligned such that the second castellation member72is locked with the first castellation member70and engine braking is activated. With reference now toFIGS.3-5, actuator assembly60is operably associated with a lash setting tool140configured to set the brake capsule assembly22in the brake ON position for mechanical lash setting. In the example embodiment, as seen inFIG.4, the lash setting tool140includes a generally cylindrical body142having a grasping end144and an insertion end146. The grasping end144is configured to be grasped by a user and the insertion end146is keyed to be inserted through an aperture148(FIG.5) at the end of bore116and subsequently received within a complementary shaped recess150(FIG.3) formed in an end of the actuator pin110. In this way, the lash setting tool140can be inserted into recess150and utilized to pull the actuator pin110to rotate the capsule assembly22to the brake ON mode to set the mechanical lash on the brake rocker arm20without removing valve train components such as, for example, injectors (not shown). In one example operation, as shown inFIG.6, the lash setting tool140is inserted into recess150and twisted to engage the actuator pin110. The lash setting tool140is then pulled, thereby pulling the actuator pin110to move the brake capsule assembly to the braking mode ON position. A wedge fork (not shown) is utilized to hold the actuator pin110in the pulled position, and a shim152is subsequently inserted between the e-foot and bridge pin36. The lash adjustment screw82is turned to close the lash at the brake capsule assembly22and bridge pin36. The lash nut88is then turned to lock the lash adjustment screw82in place. Accordingly, the design enables setting of lash on the brake arm without removing valvetrain components. The foregoing description of the examples has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular example are generally not limited to that particular example, but, where applicable, are interchangeable and can be used in a selected example, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. | 12,176 |
11859520 | DESCRIPTION As previously discussed, there exists an opportunity for improvement in the art of engine noise reduction during starting an internal combustion engine with an engine stop/start technology. Vehicle noise, vibration, and harshness (NVH) can be reduced during cranking by reducing the effective compression ratio during cranking. The effective compression ratio can be reduced by significantly by retarding the intake camshaft during engine cranking. Subsequently, the camshaft can be advanced significantly relative to the crankshaft for better fuel economy during engine firing. The instant engine system allows for the use of an aggressive Miller cycle valve actuation while maintaining seamless engine starting with a simple and cost-effective method. The instant solution requires no additional hardware to the engine thereby reducing cost compared to other techniques. The electronic phaser can be used in place of a hydraulic phaser and is a cost-effective method for reducing cranking NVH. As described herein, the present disclosure provides an electric phaser for its extended range of authority to reduce the effective compression ratio during an engine cranking event. This enables the benefit of reduced NVH during engine starting, while maintaining engine performance and fuel economy during engine operation. Using an extended range of authority electric phaser (over 75 crank degrees) enables the ability to reduce vehicle NVH during engine cranking while minimizing fuel consumption and emissions when using a cam with an aggressive EIVC strategy. The effective compression ratio of the engine can be reduced by retarding the intake camshaft during engine cranking. The camshaft can be advanced significantly relative to the crankshaft for better brake-specific fuel consumption (BSFC) during idle and higher engine speeds. As will become appreciated, an added benefit of the instant disclosure is that incorporating electric phasing allows actuation of the phaser during engine cranking prior to engine firing. This is necessary to move the camshaft from a location used for engine cranking to a location used for engine firing. Hydraulic phasers are unable to move the camshaft at low engine speeds for various reasons such as, but not limited to, inadequate camshaft location feedback and insufficient oil pressure. Camshaft phasers are used to vary camshaft timing relative to the crankshaft and are part of the variable valve timing (VVT) system. Phasers are used to maximize engine performance and fuel economy while minimizing engine out emissions. There are various types of camshaft phasers that can be mainly categorized into electric and hydraulic. A phasers range of authority is the number of crank degrees that the phaser can move the camshaft relative to the crankshaft. A typical maximum range of authority that can be expected from a hydraulic phaser is around 75 crank degrees. One added benefit to using an electric phaser, such as integrated into the instant engine system, is that the range of authority is not limited as much by the geometry of the phaser compared to that of a hydraulic vane-type phaser. Electric phasers can have a range of authority over 75 crank degrees (something that is generally not possible with hydraulic phasers). The instant disclosure provides an engine system incorporating an electric phaser for its extended range of authority to reduce the effective compression ratio during engine cranking. This enables the benefit of reduced engine starting NVH while maintaining engine performance and fuel economy during engine operation. Electric phasers have many advantages over hydraulic phasers such as an extended range of authority (ROA), phasing can occur during cranking before oil pressure is available. Phasing during cold temperature operation is more attainable with an electric phaser compared to a hydraulic phaser. Cam position is more easily monitored during cranking and shut down. Significantly less oil pressure and flow is required with an electric phaser. Referring now toFIG.1, a partial schematic representation of an electronic phaser system100that incorporates an electric phaser110according to examples of the present disclosure is shown. The electric phaser110is controlled and driven based on signals sent by an engine control module (ECM)114. In particular, the ECM114sends a command116based on various operating input signals including a cam sensor signal120, a crank sensor signal122, a diagnostics signal124and a speed/direction feedback signal126. An automatic shutdown relay module130can send a wake-up signal132to the electronic phaser110. The electronic phaser110can include a ground134and is generally be powered by a fused battery feed136that sends power input138. The electronic phaser110can generally include a motor150and a gearbox152. The electronic phaser110is connected to an intake camshaft160having lobes162. The electronic phaser110can be connected by any fastening mechanism, shown as a fastener164(FIG.4B) that suitably couples the gearbox152to the intake camshaft160. The motor150is generally driven by a chain connected to the crankshaft166(FIG.4A). The electronic phaser110therefore modifies the relative position of the intake camshaft160and crankshaft166. Turning now toFIG.2, a valve lift versus crank angle range of authority diagram is shown and generally identified at200. An exemplary exhaust valve lift is shown generally at210. An exemplary intake valve lift is shown generally at220. An exemplary intake valve lift230is shown shifted by a hydraulic phaser (according to a prior art configuration). In general, and as discussed above, a hydraulic phaser can provide a range of authority of around 75 crank degrees. While moving the camshaft around 75 crank degrees is beneficial for NVH, such as during engine cranking, the effective compression ratio is still undesirably high (such as, for example, around 12:1). The range of authority offered by a hydraulic phaser can generally be limited (such as to about 100 crank degrees) by the geometry of the hydraulic phaser. An exemplary intake valve lift240is shown shifted by an electric phaser110of the electronic phaser system100according to the present disclosure. As shown, the electric phaser110can provide a greater phase shift enabling lower compression ratio (such as, for example, around 5:1) for cranking. In the example shown, the electric phaser110can move the camshaft160about 130 crank degrees. As can be appreciated, a reduced compression ratio at startup will reduce NVH. As used herein around 5:1 can mean between 5:1 and 6:1. Similarly, about 130 crank degrees can mean between 120 and 150 crank degrees. With reference toFIG.3, an exemplary flow chart for an engine stop request400and an engine start request450using the electronic phaser system ofFIG.1according to examples of the present disclosure will be described. In general, the engine stop and start requests400and450can be carried out by commands sent by the ECM114. For an engine stop request400, an engine stop is requested at410. At412, a cranking compression ratio is targeted. At414a compression ratio is converted to camshaft lobe centerline. Of note, with a Miller valve event, this compression ratio requires the intake camshaft160to move beyond the range of authority that a hydraulic phaser can offer. With the electronic phaser110of the instant disclosure, the desired compression ratio targeted is attainable. At418, the electric phaser150moves the intake camshaft160to a desired position through proportional-integral-derivative (PID) feedback control. At420the desired position of the intake camshaft160is achieved at or before the engine reaches 0 RPM. For an engine start request450, an engine start is requested at460. At462, a cranking compression ratio is targeted. At464a compression ratio is converted to camshaft lobe centerline. At468, the electric phaser110moves the intake camshaft160to a desired position through PID feedback control. At470the engine fires and the intake camshaft160moves to an advanced centerline condition. Turning now toFIG.4(shown collectively asFIGS.4A and4B), an engine system500that incorporates the electronic phaser system100will be described. In general, the engine system500includes the intake camshaft160and an exhaust camshaft510. The exhaust camshaft510can be driven by an exhaust cam phaser512. The exhaust cam phaser512can be a hydraulic cam phaser that is generally driven by an actuator520. An oil control valve522fed by an oil control circuit526can control an amount of oil pressure at the exhaust cam phaser512. A front cover530includes position and seal actuators for the electric phaser110(on the intake side) and the actuator520of the phaser512(on the exhaust side). The gearbox152regulates torque to the intake camshaft160and further limits the range of authority. A timing drive536provides a timing input to the gearbox152and the exhaust cam phaser512. An exhaust trigger wheel540generates a reference target signal to an exhaust cam sensor544to produce an exhaust cam position signal. An intake trigger wheel550generates a reference target signal to the intake cam sensor120to produce an intake cam position signal. In general, a head560enables rotational movement of the intake camshaft160and exhaust camshaft510. The intake and exhaust camshafts160,510transfer rotational energy to a roller finger follower (RFF) in valvetrain570. As used herein, the term controller or module refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. It will be understood that the mixing and matching of features, elements, methodologies, systems and/or functions between various examples may be expressly contemplated herein so that one skilled in the art will appreciate from the present teachings that features, elements, systems and/or functions of one example may be incorporated into another example as appropriate, unless described otherwise above. It will also be understood that the description, including disclosed examples and drawings, is merely exemplary in nature intended for purposes of illustration only and is not intended to limit the scope of the present disclosure, its application or uses. Thus, variations that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. | 10,621 |
11859521 | Identical and functionally identical elements are provided with identical reference numbers in the FIGS. DETAILED DESCRIPTION OF THE DRAWINGS FIG.1shows in part, in a schematic perspective view, a measuring rod1for measuring a fill level of a lubricant in a reservoir2(FIG.4) of an internal combustion engine for a motor vehicle. The motor vehicle formed preferably as a motor car, in particular as a car, can be driven by means of the internal combustion engine also referred to in short as an engine or combustion engine. The lubricant can be an oil which is also referred to as lubricating oil. For example, reservoir2is thus formed as an oil pan. The internal combustion engine is lubricated at respective lubrication points by means of the oil. For this purpose, the lubrication points are supplied with the oil. Once the lubrication points have been supplied with the oil and lubricated by means of the oil, the oil can flow from the lubrication points to reservoir2and is gathered and collected in the reservoir or by means of reservoir2. As a result of this, for example, the lubricant in reservoir2forms an oil sump also referred to as a sump. Measuring rod1can thus be used to measure a fill level and thus a quantity of oil accommodated in reservoir2. To this end, measuring rod1has a rod element3which is apparent in part inFIG.1, is formed, for example, from a metallic material and has a longitudinal extent. It is apparent when viewed together withFIG.2that rod element3has a reservoir-side first end4and a second end5opposite first end4(FIG.5). A measuring tongue6of measuring rod1is arranged at first end4, in particular fastened to rod element3. Rod element3and measuring tongue6are structural elements which are, for example, already formed by one another and connected to one another, wherein measuring tongue6is formed, for example, from a plastic. Rod element3is, for example, also referred to as a braid. Measuring tongue6has, for example, a measuring region7and wiper beads8and9adjoining measuring region7on both sides in the longitudinal direction of extent of measuring tongue6. For example, measuring tongue6is formed in one piece so that, for example, wiper beads8and9are formed in one piece with one another and in one piece with measuring region7. Measuring tongue6can be immersed at least partially into the sump and thus into the oil. As a result of this, measuring tongue6is at least partially wetted with the oil. Overall, measuring tongue6, in particular measuring region7, is wetted with the oil as a function of the current fill level of the oil in reservoir2. The larger, for example, the part of measuring tongue6which is wetted with the oil during immersion of measuring tongue6into the oil accommodated in reservoir2, the greater or higher the fill level in reservoir2. For example, a person can visually determine the wetting of measuring tongue6and thus read it from measuring tongue6so that the person can measure and visually determine the fill level. The person can thus measure and visually determine the fill level by means of measuring tongue6. In order to be able to realize particularly simple leakage testing and particularly advantageous readability of measuring tongue6and be able to keep the costs particularly low, measuring rod1has at least or precisely one seal element10which is arranged on measuring tongue6and formed, for example, as an O-ring and by means of which measuring rod1is to be sealed off or is sealed off from a guide tube11which can be seen partially inFIG.1for guiding measuring rod1. FIGS.2,3and5show an arrangement12of measuring rod1in guide tube11. In the case of arrangement12, measuring rod1is received in such a manner in guide tube11and pushed into guide tube11that a handle element20of measuring rod1provided on second end5and also referred to in short as a handle or handle piece is pushed partially into guide tube11and is thus received partially in guide tube11and is arranged partially outside guide tube11since handle element20protrudes out of guide tube11. Measuring rod1can be handled by the above-mentioned person via handle element20. To this end, the person grips or grips around handle element20. The person can handle measuring rod1via handle element20in such a manner that the person pushes measuring rod1into guide tube11and can push it through guide tube11in particular until measuring rod1comes into supporting bearing with guide tube11, in particular via handle element20. As is apparent fromFIG.2, a first sub-region T1of measuring tongue6then protrudes out of guide tube11and a second sub-region T2of measuring tongue6adjoining sub-region T1is accommodated within guide tube11and thereby in a guide channel13of guide tube11delimited by guide tube11. In this case, seal element10is arranged in second sub-region T2so that second sub-region T2is sealed off from guide tube11, in particular from an inner circumferential shell surface14of guide tube11delimiting guide channel13, by means of seal element10or via seal element10. In particular, measuring tongue6is sealed off from a longitudinal region L of guide tube11also referred to as a sub-region by means of seal element10, wherein longitudinal region L is not arranged outside reservoir2, but rather still in reservoir2and thus in a lubricant chamber also referred to as an oil chamber. It is particularly apparent from a combined view ofFIGS.2and5that measuring tongue6is sealed off from guide tube11, in particular from longitudinal region L, by means of seal element10at a sealing point D. Guide tube11has itself a reservoir-side first end E1and a second end E2, opposite first end E1, and on the handle element side. It is apparent fromFIG.4that guide tube11is connected to reservoir2, wherein, for example, at least longitudinal region L is arranged in reservoir2. While, for example, first end E1is thus received in reservoir2, second end E2is arranged outside reservoir2. Sealing point D is arranged at end E1or in the vicinity of end E1and significantly closer to end E1than to end E2. For example, oil which is, for example, stirred up and thus penetrates from reservoir2into guide channel13can thus not travel to end E2, but rather only to sealing point D since sealing point D is impervious to the oil from the reservoir2. Since longitudinal region L and thus sealing point D are still arranged in reservoir2, one hundred percent imperviousness of guide tube11is not necessary since oil from reservoir2cannot travel to this leak, for example, when guide tube11itself has a leak which is arranged outside reservoir2. If, for example, a leak of guide tube11is arranged in longitudinal region L and thereby between end E1and sealing point D, so that, for example, oil can travel from reservoir2to this leak, this is not at all critical since oil which escapes from guide tube11at the leak travels back into reservoir2. InFIG.2, an arrow15illustrates a dry chamber or dry region of guide channel13, wherein the dry region of guide channel13extends from sealing point D up to end E2. No oil can travel into this dry region from reservoir2since oil can only travel from reservoir2up to sealing point D in guide channel13. Moreover, inFIG.2, an arrow16illustrates the oil chamber or a region into which oil can travel from reservoir2. Seal element10formed, for example, as an O-ring and arranged on measuring tongue6seals off measuring tongue6from inner circumferential shell surface14, as a result of which the oil chamber illustrated by arrow16is separated off with respect to the dry region. The dry region is in this case entire guide channel13or its entire volume with the exception of a small part which extends from sealing point D up to end E1. Neither oil nor oil mist travels from reservoir2into the dry region. It is apparent fromFIG.4that, for example, guide tube11, in particular its outer circumferential shell surface17facing away from inner circumferential shell surface14, is sealed off from reservoir2by means of a further seal element18formed in particular as an O-ring. For this purpose, seal element18is arranged at least partially in a groove19of guide tube11, wherein groove19faces away from guide channel13. Groove19is represented, for example, by a rolling up of guide tube11, wherein seal element18is arranged or sits directly on outer circumferential shell surface17. While, for example, seal element10prevents oil from flowing out of reservoir2into guide channel13between measuring rod1and guide tube11, seal element18prevents oil from flowing through out of reservoir2between guide tube11and reservoir2itself. As a result of this, particularly advantageous imperviousness can be realized. FIG.3shows arrangement12, in the case of which measuring rod1is located in its end position. In the end position, handle element20is pushed in, in particular completely, so that measuring rod1is pushed as far as possible into guide tube11and through guide tube11. A further pushing in of measuring rod1into guide tube11is avoided by handle element20since handle element20is located in the end position with supporting bearing against guide tube11. It is particularly easily apparent fromFIG.3that measuring tongue6has, in particular in sub-region T2, a groove21in which seal element10is received partially, in particularly exclusively. Seal element10is partially arranged in groove21and partially outside groove21so that seal element10is supported in the case of arrangement12and in the end position on one hand on measuring tongue6and on the other hand on guide tube11. Seal element10and/or seal element18are preferably formed from a rubber. It is apparent fromFIG.5that it is in principle possible to seal off handle element20by means of a further, third seal element22from guide tube11, in particular from its inner circumferential shell surface14. It has, however, been shown to be particularly advantageous if measuring rod1is sealed off exclusively by means of seal element10from guide tube11, as a result of which the number of parts and thus costs can be kept particularly low. In other words, it is preferably provided that the sealing, which is illustrated inFIG.5and is performed via seal element22, of measuring rod1from guide tube11is dispensed with. LIST OF REFERENCE NUMBERS 1Measuring rod2Reservoir3Rod element4First end5Second end6Measuring tongue7Measuring region8Wiper bead9Wiper bead10Seal element11Guide tube12Arrangement13Guide channel14Inner circumferential shell surface15Arrow16Arrow17Outer circumferential shell surface18Seal element19Groove20Handle element21Groove22Seal elementD Sealing pointL Longitudinal regionE1, E2EndT1First sub-regionT2Second sub-region | 10,680 |
11859522 | DETAILED DESCRIPTION OF THE PRESENT INVENTION The present invention finds particularly advantageous application when implemented in internal combustion engines, both of multi-cylinder type and single-cylinder type, for example with poppet valves, in particular for vehicles with a rideable saddle, this being the reason why the present invention will be described below with possible particular reference to engines of the aforesaid type. The possible applications of the present invention however are not limited to engines of the aforesaid type alone, the present invention on the contrary being suitable to be used and implemented in all cases in which the effective and reliable lubrication of linkages is required, such as for example in the case of air compressors. System100depicted according to the embodiment inFIGS.1to3comprises a crank chamber110, a basin or pan120for collecting a lubricating liquid (e.g. oil) LL, wherein the crank chamber110communicates with a cylinder in which a piston P is accommodated, the reciprocating translating motion of which, generated by the combustion of fuel, is transformed into the rotation motion of the drive shaft by means of linkages accommodated in the crank chamber110and not depicted in the drawings both because they differ according to the types of engine and because they are not essential for the purposes of the present invention; by way of example and for completeness of description, said linkages may comprise one or more connecting rods or similar components. The crank chamber110and pan or basin120are put in mutual communication by an opening111obtained at the bottom of chamber110, in particular in the lowest part of the bottom of chamber110, in detail at bottom114of an accumulation sump113. Moreover, an adjustment element (of the flow of lubricating liquid from chamber110into pan120, see the following description) is positioned at opening111, practically a reed valve (with flexible reed)112adapted to be switched between a closed position (not depicted) in which it closes opening111, thus preventing the flow of lubricating liquid LL from chamber110into pan120, and the open position inFIG.1, in which the flow of lubricating liquid LL from chamber110to pan120may be possible instead. Practically, the operating modes of system100inFIGS.1to3, partially corresponding to the operating modes of systems according to the prior art, may be summarized as follows. The lubricating oil LL is drawn from the collecting and accumulation pan120and introduced into the crank chamber or crankcase110through the hydraulic circuit (not depicted and including pump, valves, etc . . . ); moreover, the reciprocating translating motion of piston P translates into the introduction of pressurized gas into chamber110, which prevents the chamber110itself from having a pressure drop during the rising movement of piston P. The lubricating oil LL repeatedly introduced (in substantially continuous manner) into chamber110accumulates on the bottom of chamber110, in particular at least partially in the accumulation sump113, to be cyclically discharged into pan120through opening111. Indeed, as the pressure in chamber110rises, the flexible reed (for example made of PVC)112is subjected to increasing pressure up to bending (switching from the closed position inFIG.1ato the open position inFIG.1b) at a predetermined pressure value (inversely proportionate to the flexibility of reed112), thereby opening the opening111and allowing the discharge of oil LL and of the gases from chamber110to pan120. However, as mentioned, system100according to the present invention comprises peculiarities aiming to increase the frequency with which the mixture of lubricating oil LL and gas in chamber110is discharged into pan120. Indeed, numeral140in the drawings identifies a further opening obtained in the outer wall of the crank chamber110; as in the case of opening111, opening140is provided with a reed valve (having flexible reed)141adapted to be switched by bending between a closed position (FIG.1b, in which it closes opening140) and an open position (FIG.1a) in which it frees opening140, thus allowing the introduction of pressurized gas into the crank chamber110. Obviously, the introduction of pressurized gas (e.g. air) into chamber110in addition to the blow-by gases or originating from another source, reduces the time required for the switching pressure of the reed valve112to be reached in chamber110, whereby: the time is reduced between two successive switching operations (both in open position) of reed112; the switching frequency of reed112is increased; the amount of lubricating liquid LL which can be accumulated in chamber110between two successive switching operations of reed112is reduced. The interior of the crank chamber110is put in communication by means of a circuit which leads into opening140, with a further zone of said internal combustion engine, in particular with a source of air inside the engine, for example with an HPC (High Pressure Cooled) system. Depending on the source of air, or more generally pressurized gas, an amount of gas (e.g. air) in a grater order of magnitude than that of the blow-by gases may be introduced, in the time unit, into the crank chamber110. In the embodiment inFIGS.3to7, the second reed141is accommodated in a compartment150(closed by means of a removable cover160) into which an introduction channel151in communication with the exterior of said compartment150for introducing said pressurized gas into said compartment150, and a second channel170lead, the latter defining the opening140, wherein the interior of compartment150is put in communication with the interior of the crank chamber110by means of channel170. In the embodiment depicted inFIGS.6and7, the interior of compartment150is put in communication with the chain compartment and/or the flywheel cover compartment500of the engine by means of channel151, said chain compartment and/or flywheel cover compartment in turn being in communication with the oil pan120, wherein a closed recirculation of air is thus generated from pan120into the crank chamber110without the need to draw on air or gas from the exterior; indeed, the flow of air generated by said moving chain and/or flywheel compartments is introduced into compartment150, wherein in the closed position reed141separates compartment150into a first half-compartment into which channel151leads and a second half-compartment into which channel170leads. The closed recirculation of air which occurs from pan120into the crank chamber110and the chain and/or flywheel compartments allows the flow of air ejected from the blow-by valve to be limited, therefore limiting the ejection of oil-enriched vapors and fumes, and thus reducing the consumption of oil. Indeed, by drawing air from the exterior of the engine, it is noted how such an amount of air is to be then ejected through the blow-by valve. In particular, it is found that by drawing fresh air from the exterior, the flow of ejected air with respect to an internal recirculation is about four times greater. Such an increased outlet flow generates:increased fumes and vapors; such fumes and vapors being oily vapors which therefore contain oil from cleaning the crank chamber. Therefore, there is an increased consumption of oil with the ejection of such vapors. In the above-mentioned solution, channel151causes a closed recirculation of air in which the air is drawn internally from the chain and/or flywheel compartments. This causes an air exchange between two closed internal volumes. Therefore, the air does not originate from the exterior, rather is recirculated from the interior. This solution allows obtaining an effective cleaning of the crank chamber, as described above, thus reducing the temperature of the oil which remains in the crank chamber for less time, it being ejected more frequently by means of reed141, by virtue of the overpressure obtained with the introduction of air. This is due to the increase in the average pressure in the crank chamber, which promotes the disposal of the oil and therefore prevents grinding effects which cause power losses and high temperatures. Additionally, such a solution allows the flow of air ejected outside by means of the blow-by valve to be limited, thus accordingly reducing the fumes and vapors and the consumption of oil itself. As it is an internal air recirculation, the flow ejected outside is less than the amount of air introduced from the exterior; this results in a reduction of fumes and vapors and accordingly, in a reduction of the consumption of oil. Then, and in particular when the pressure of the air in the compartment150reaches the switching value of reed141, the switching of the reed141to open position results in the mutual communication of the channels151and170, and therefore in the introduction of air from the HPC system and/or from the chain compartment and/or from the flywheel compartment into the crank chamber110, with the effects explained above of the increase in switching frequency of reed112. Further peculiarities of the system according to the present invention are described below with reference toFIGS.1to7. As depicted, a fixed insert130is accommodated in chamber110in order to decrease the free inner volume (not occupied by movable linkages) of the crank chamber110. Said insert130has a trapezoidal cross section (according to a plane parallel to the plane on which the connecting rod moves, and therefore perpendicular to the rotation axis of the drive shaft) and is located at sump113, at a predetermined distance from bottom114thereof (so as not to hinder the accumulation of oil LL in sump113), in particular at least partially in the projection of opening111(shown by a dashed line) and so as to define a conveying channel115for conveying said lubricating liquid LL into said collection and drainage sump113. Due to insert110, the predetermined gas pressure value at which reed112switches by bending from the closed position to the open one (hereinafter also defined switching pressure value) is reached inside said crank chamber110in the presence of a volume of lubricating liquid LL which is less than the volume of lubricating liquid LL in the presence of which said predetermined gas pressure value would be reached in the absence of said fixed insert130, wherein obviously the decrease of the amount of oil needed to reach the switching gas pressure results in more frequent switching of reed112(or in other words, in an increase in the switching frequency), and therefore in a decrease in the amount of liquid LL accumulated between two successive switching operations (both from the closed position to the open one) of the flexible reed112, wherein the difference between the volume of lubricating liquid LL in the presence of which said predetermined switching pressure value would be reached in the absence of the fixed insert130and the volume of lubricating liquid LL in the presence of which said predetermined switching pressure value is actually reached substantially is (by virtue of insert130) equal to the difference between the free inner volume of the crank chamber110and the volume of the fixed insert130. As mentioned, the reduction of the amount of lubricating liquid LL which can be accumulated in chamber110between two successive switching operations of reed112results in a reduction of the risk for the drive shaft to interfere with the accumulated oil, and of the further risk for the oil accumulated to be subject to drifting phenomena during the movement of the vehicle, in particular in a bend, thus even compromising the stability thereof (due to the effect of the movement of the center of gravity). Depending on the applications, the volume of said fixed insert130may be between 20% and 70%, preferably between 35% and 55% of the free inner volume of the crank chamber110. Therefore, by the above detailed description of the embodiments of the present invention as depicted in the drawings, it has been demonstrated that the present invention allows the preset objects to be achieved, thus overcoming the drawbacks and/or disadvantages affecting the solutions according to the prior art. For example, the present invention allows providing a ventilation and/or lubrication system, the operating modes of which are more similar to those of a “dry crankcase” than to those of a “wet crankcase”, and which allows avoiding excessive accumulations of lubricating liquid at the shaft of the crank chamber for long time periods. Although the present invention was clarified above by means of the detailed description of the embodiments depicted in the drawings, the present invention is not limited to the embodiments described above and depicted in the drawings; on the contrary, all those variants and/or modifications of the embodiments described above and depicted in the accompanying drawings which are apparent and obvious to those skilled in the art fall within the scope of the present invention. The scope of protection of the present invention is thus defined by the claims. | 13,133 |
11859523 | DETAILED DESCRIPTION The following detailed description is merely exemplary in nature and is not intended to limit the application and uses. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. In addition, those skilled in the art will appreciate that embodiments of the present disclosure may be practiced in conjunction with any type of device that would benefit from sound attenuation and the use of the muffler with an auxiliary power unit or a micro power unit described herein is merely one exemplary embodiment according to the present disclosure. In addition, while the muffler is described herein as being used with an auxiliary power unit or a micro power unit onboard a vehicle, such as a bus, motorcycle, train, motor vehicle, marine vessel, aircraft, rotorcraft and the like, the various teachings of the present disclosure can be used with an engine on a stationary platform. Further, it should be noted that many alternative or additional functional relationships or physical connections may be present in an embodiment of the present disclosure. In addition, while the figures shown herein depict an example with certain arrangements of elements, additional intervening elements, devices, features, or components may be present in an actual embodiment. It should also be understood that the drawings are merely illustrative and may not be drawn to scale. As used herein, the term “axial” refers to a direction that is generally parallel to or coincident with an axis of rotation, axis of symmetry, or centerline of a component or components. For example, in a cylinder or disc with a centerline and generally circular ends or opposing faces, the “axial” direction may refer to the direction that generally extends in parallel to the centerline between the opposite ends or faces. In certain instances, the term “axial” may be utilized with respect to components that are not cylindrical (or otherwise radially symmetric). For example, the “axial” direction for a rectangular housing containing a rotating shaft may be viewed as a direction that is generally parallel to or coincident with the rotational axis of the shaft. Furthermore, the term “radially” as used herein may refer to a direction or a relationship of components with respect to a line extending outward from a shared centerline, axis, or similar reference, for example in a plane of a cylinder or disc that is perpendicular to the centerline or axis. In certain instances, components may be viewed as “radially” aligned even though one or both of the components may not be cylindrical (or otherwise radially symmetric). Furthermore, the terms “axial” and “radial” (and any derivatives) may encompass directional relationships that are other than precisely aligned with (e.g., oblique to) the true axial and radial dimensions, provided the relationship is predominantly in the respective nominal axial or radial direction. As used herein, the term “substantially” denotes within 5% to account for manufacturing tolerances. For the sake of brevity, conventional techniques related to signal processing, data transmission, signaling, control, and other functional aspects of the systems (and the individual operating components of the systems) may not be described in detail herein. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent example functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in an embodiment of the present disclosure. With reference toFIG.1, a functional block diagram illustrates a muffler200employed with an exemplary engine102. In this example, the engine102is associated with a power unit104, which is onboard a vehicle106. For example, the power unit104may be employed with various applications including aerospace (small jets and turboprops; charter companies; fractional companies; corporate fleets; and special mission aircraft). Other applications include military vehicles (e.g., M1 Tank, Joint Light Tactical Vehicle, Paladin, etc.); mobile command posts; mobile medical facilities; and emergency response. Ground based vehicle applications include tracked vehicles and artillery pieces. Military ground power equipment applications include command posts, remote power supplies, medical units, and integrated aircraft systems. Portable power systems applications include remote power generation systems and rapid deployment power systems. Thus, in other examples, the power unit104(including the engine102and the muffler200) may be employed on a stationary platform. As will be discussed, the muffler100receives exhaust gases108from the engine102, and attenuates the sound generated by the engine102to reduce the noise experienced by passengers, crew, and service personnel. In certain instances, the muffler200may also receive cooling fluid, such as cooling air110, from the engine102or a cooling fan116associated with the engine102, which may be used to cool the muffler200. After passing through the muffler200, the exhaust gases108may exit the power unit104and the vehicle106, or may be directed to another secondary muffler downstream. The engine102comprises any suitable engine, including, but not limited to, a gas turbine engine, an internal combustion engine, a Wankel engine, etc. As the muffler200may be employed with any type of engine102that generates the exhaust gases108and optionally cooling air110, the engine102will not be discussed in detail herein. Briefly, in the example of the engine102as a Wankel engine, the engine102employs an eccentric rotary design to convert pressure into rotating motion. The engine102is configured to combust a fuel and air mixture to generate the rotary movement, which is used to generate electrical power. The fuel is any suitable combustible fuel, including, but not limited to jet fuel (unleaded kerosene or a naphtha-kerosene blend), aviation gasoline, biofuels, diesel, gasoline, and the like. In one example, the engine102includes one or more spark coils to generate an electric spark to ignite the fuel, and the resulting combustion drives a rotor of the engine102. The rotor, in turn, drives an output shaft112. One end of the output shaft112is coupled to a starter-generator114to drive the starter-generator114to generate electric power for the vehicle106, and the other end of the output shaft112is coupled to the cooling fan116. The cooling fan116provides the cooling air110to cool the engine102and the muffler200. The electric power generated by the starter-generator114is provided to a consumer118associated with the vehicle106, including, but not limited to a heating, ventilation and cooling system, a lighting system, a starter system, a flight instrument system, etc. The power unit104comprises an auxiliary power unit or a micro power unit, which is coupled to the vehicle106to supply electrical power when the vehicle106is on the ground, for example. As the muffler200and the engine102may be associated with any type of power unit104, the power unit104will not be discussed in detail herein. Briefly, in one example, the power unit104is a micro power unit, such as that described in commonly assigned U.S. application Ser. No. 16/367,564, filed on Mar. 28, 2019 to Dittmar et. al., and published as U.S. Publication No. 2019/0308741, the relevant portion of which is hereby incorporated by reference herein. The engine102, the starter-generator114, the cooling fan116and the muffler200may be contained within a housing120to enable the power unit104to be removable from the vehicle106. Generally, as discussed, the power unit104includes the engine102, which generates power to drive the starter-generator114to supply electric power to the consumer118of the vehicle106. As discussed, the muffler200is in fluid communication with the engine102to receive the exhaust gases108, and optionally, is in fluid communication with the cooling fan116to receive the cooling air110. With reference toFIG.2, and additional reference toFIG.3, the muffler200is shown in greater detail. In on example, the muffler200includes a housing202, a header pipe204(FIG.3), a pressure attenuator206(FIG.3), a first, forward chamber208, a first tube or first transfer tube210(FIG.3), a second, outer chamber212(FIG.3), a second tube or second transfer tube214(FIG.3), a third, aft chamber216, a third tube or exhaust pipe218and a deswirl assembly220. With reference toFIG.3, the housing202surrounds and encloses the pressure attenuator206, the forward chamber208, the first transfer tube210, the outer chamber212, the second transfer tube214, and the aft chamber216. The housing202also encloses and surrounds a portion of the header pipe204and the exhaust pipe218. The housing202is composed of a metal or metal alloy, and may be cast, stamped, forged, or additively manufactured. In this example, the housing202includes a first housing wall222, a second housing wall224and a third housing wall226. The first housing wall222is upstream from the third housing wall226in a direction of fluid flow through the muffler200. The first housing wall222is substantially frustoconical, however, the first housing wall222may have any desired shape. The second housing wall224is coupled to the first housing wall222and the third housing wall226. The second housing wall224is substantially cylindrical. The second housing wall224also defines an intake bore230(FIG.4). The intake bore230enables a portion of the header pipe204to pass into the interior of the housing202. The third housing wall226is substantially conical, and defines an exhaust bore232. The exhaust bore232enables a portion of the exhaust pipe218to pass out of the housing202. The header pipe204is fluidly coupled to the engine102to receive the exhaust gases108. The header pipe204is received through the intake bore230, and terminates at the pressure attenuator206at an end204a. In this example, with reference toFIG.4, the header pipe204bends or curves between the intake bore230and the end204ato direct the exhaust gases108into a center of the pressure attenuator206. In one example, the header pipe204extends through a sub-housing215associated with the second transfer tube214. The end204aof the pressure attenuator206is received and coupled to an annular flange233, which extends axially outward from a portion of the pressure attenuator206. The pressure attenuator206extends radially within the housing202. In one example, the pressure attenuator206includes two spaced apart plates, a first plate240and an opposed second plate242. In this example, each of the first plate240and the second plate242are circular to comport with the shape of the second housing wall224, however, the first plate240and the second plate242may have any desired shape, including, but not limited to, rectangular, oval, square, etc. With brief reference toFIG.5, the first plate240includes at least a pair of nested protrusions, and in this example, the first plate240includes five first protrusions246a-246e. With reference back toFIG.3, in this example, the first protrusions246a-246eare concentric to a central axis C of the first plate240and the second plate242, and are substantially evenly spaced radially along a longitudinal axis L of the muffler200. It should be noted that the first protrusions246a-246emay be arranged in other patterns on the first plate240and may not be evenly spaced. Each of the first protrusions246a-246eextend axially from a first surface240aof the first plate240. The first surface240ais opposite a second surface240b. In this example, each of the first protrusions246a-246eare planar or extend from the first surface240aalong an axis substantially parallel to the central axis C. In other examples, the first protrusions246a-246emay extend from the first surface240aat an angle so as to extend along an axis oblique to the central axis C. Each of the first protrusions246a-246ehave an end coupled to the first surface240a, and an opposite end or terminal end248. The terminal end248of each of the first protrusions246a-246eis spaced apart from a third surface242aof the second plate242. With brief reference toFIG.6, the second plate242includes at least a pair of nested protrusions, and in this example, the second plate242includes five second protrusions250a-250e. With reference back toFIG.3, in this example, the second protrusions250a-250eare concentric to the central axis C of the first plate240and the second plate242, and are substantially evenly spaced radially along the longitudinal axis L of the muffler200. It should be noted that the second protrusions250a-250emay be arranged in other patterns on the second plate242and may not be evenly spaced. Each of the second protrusions250a-250eextend axially from the third surface242aof the second plate242. The third surface242ais opposite a fourth surface242b. In this example, each of the second protrusions250a-250eare planar or extend from the third surface242aalong an axis substantially parallel to the central axis C. In other examples, the second protrusions250a-250emay extend from the third surface242aat an angle so as to extend along an axis oblique to the central axis C. Each of the second protrusions250a-250ehave an end coupled to the third surface242a, and an opposite end or terminal end252. The terminal end252of each of the second protrusions250a-250eis spaced apart from the first surface240aof the first plate240. In this example, the second plate242defines a bore254that forms an inlet of the pressure attenuator206. The bore254is fluidly coupled to the header pipe204. The annular flange233is defined about the bore254and extends outwardly from the fourth surface242bof the second plate242. In this example, the first protrusions246a-246eand the second protrusions250a-250eare circular, however, it should be noted that the first protrusions246a-246eand the second protrusions250a-250emay have any desired shape. In one example, with reference back toFIG.5, the second plate242is coupled to and integrally formed with the second housing wall224. In this example, a plurality of struts253interconnect the second plate242with the second housing wall224. The struts253are spaced apart about the circumference of the second plate242and the second housing wall224to define a plurality of apertures255. Each of the apertures255has a generally race-track shape. The apertures255enable the fluid to flow along the exterior of the second housing wall224in the outer chamber212. The third housing wall226is coupled to the second housing wall224and is in fluid communication with the apertures255. As will be discussed, the sub-housing215fluidly isolates the aft chamber216from the outer chamber212. With reference back toFIG.3, in this example, the first protrusions246a-246eface the second protrusions250a-250eand are offset or misaligned from the second protrusions250a-250ealong the longitudinal axis L. By spacing the terminal end248,252of the first protrusions246a-246eand the second protrusions250a-250e, respectively, from the corresponding one of the first surface240aand the third surface242aand misaligning the first protrusions246a-246efrom the second protrusions250a-250e, an undulating tortuous path256for the exhaust gases108is defined between the first protrusions246a-246eand the second protrusions250a-250ealong the longitudinal axis L. The tortuous path256extends radially from the inlet defined by the bore254to an outer perimeter or circumference258of the first plate240. The outer circumference258of the first plate240is spaced apart from a chamber wall260of the forward chamber208and defines an outlet262about the outer circumference258for the exhaust gases108to enter into the forward chamber208. The tortuous path256results in pressure loss for the exhaust gases108, which has to make sharp turns to pass between gaps257defined between the respective terminal end248,252and the respective first surface240aand third surface242a. The tortuous path256reduces pressure, and thus, velocity of incoming flow. The velocity reduction limits flow noise generation, while incoming acoustic pulses are also attenuated via viscous dissipation along the long path length out of the first plate240and the second plate242. It should be noted that while the terminal end248,252is illustrated herein as being smooth, the terminal end248,252of one or more of the first protrusions246a-246eand the second protrusions250a-250emay be serrated, scalloped, or have a different shape. In addition, while the first plate240and the second plate242are illustrated herein as extending along the longitudinal axis L over substantially an entirety of the forward chamber208, in other embodiments, the first plate240and the second plate242may have a reduced height or length along the longitudinal axis L such that the first plate240and the second plate242extend along the longitudinal axis L for only a portion of the forward chamber208. The first plate240and the second plate242are each composed of metal or metal alloy, and may be stamped, cast, machined, additively manufactured, etc. In one example, the first plate240and the second plate242may be stamped with grooves for the first protrusions246a-246eand the second protrusions250a-250e, respectively, and the first protrusions246a-246eand the second protrusions250a-250emay be separately formed, via stamping, for example, and fixedly coupled to the grooves of the respective first plate240and the second plate242via welding or brazing, for example. Optionally, one or more pins may be employed to couple the first plate240to the second plate242to maintain the gap257between the first plate240and the second plate242. It should be noted that in other embodiments, the pressure attenuator206for the muffler200may be configured differently to define the tortuous path256to reduce pressure and velocity of incoming airflow. For example, with reference toFIG.7, a side view of a pressure attenuator300is shown. As the pressure attenuator300includes components that are the same or similar to components of the pressure attenuator206discussed with regard toFIGS.1-6, the same reference numerals will be used to denote the same or similar components. The pressure attenuator300extends radially within the housing202. It should be noted that the housing202may be modified, if desired, to accommodate the shape of the pressure attenuator300. In one example, the pressure attenuator300includes two spaced apart plates, a first plate302and an opposed second plate304. In this example, with reference toFIG.8, each of the first plate302and the second plate304are substantially D-shaped. With reference toFIG.9, the first plate302includes at least a pair of nested protrusions, and in this example, the first plate302includes four first protrusions312a-312d. The first protrusions312a-312dare nested relative to each other about an axis A300of the first plate302and the second plate304(FIG.7), and are substantially evenly spaced along a first surface302aof the first plate302. It should be noted that the first protrusions312a-312dmay be arranged in other patterns on the first plate302and may not be evenly spaced. Each of the first protrusions312a-312dextend axially from the first surface302aof the first plate302. The first surface302ais opposite a second surface302b. In this example, each of the first protrusions312a-312dare planar or extend from the first surface302aalong an axis substantially parallel to the axis A300. In other examples, the first protrusions312a-312dmay extend from the first surface302aat an angle so as to extend along an axis oblique to the axis A300. Each of the first protrusions312a-312dhave an end coupled to the first surface302a, and an opposite end or terminal end314. The terminal end314of each of the first protrusions312a-312dis spaced apart from a third surface304aof the second plate304. With reference back toFIG.8, the second plate304includes at least a pair of nested protrusions, and in this example, the second plate304includes four second protrusions316a-316d. The second protrusions316a-316dare nested relative to each other about an axis A300of the first plate302and the second plate304, and are substantially evenly spaced along the third surface304aof the second plate304. It should be noted that the second protrusions316a-316dmay be arranged in other patterns on the second plate304and may not be evenly spaced. Each of the second protrusions316a-316dextend axially from the third surface304aof the second plate304. The third surface304ais opposite a fourth surface304b. In this example, each of the second protrusions316a-316dare planar or extend from the third surface304aalong an axis substantially parallel to the axis A300(FIG.7). In other examples, the second protrusions316a-316dmay extend from the third surface304aat an angle so as to extend along an axis oblique to the axis A300. Each of the second protrusions316a-316dhave an end coupled to the third surface304a, and an opposite end or terminal end318. The terminal end318of each of the second protrusions316a-316dis spaced apart from the first surface302aof the first plate302. In this example, the second plate304defines the bore254that forms an inlet of the pressure attenuator300. With brief reference toFIG.9, as discussed, the bore254is fluidly coupled to the header pipe204. The annular flange233is defined about the bore254and extends outwardly from the fourth surface304bof the second plate304. In this example, the first protrusions312a-312dand the second protrusions316a-316dhave an arbitrary shape or a polygonal shape. With reference toFIGS.8and9, each of the first protrusions312a-312dand the second protrusions316a-316dhave a substantially D-shape or include a planar segment330and an arcuate segment332that cooperate to enclose a volume. The planar segment330extends substantially perpendicular to the longitudinal axis L. The volume enclosed by the planar segment330and the arcuate segment332is different or increases from the innermost first protrusion312aand the innermost second protrusion316ato the outermost first protrusion312dand the outermost second protrusion316d. It should be noted that the D-shape illustrated and described herein is merely just one example of a polygonal shape that may be employed to form one or more of the first protrusions312a-312dand the second protrusions316a-316d. Other examples include, but are not limited to stars, pentagons, lobed-shapes, daisy shapes, etc. In addition, it should be noted that a pressure attenuator may be formed in which protrusions having the shape of the first protrusions312a-312dand/or the second protrusions316a-316dalternate with the circular shape of the first protrusions246a-246eand the second protrusions250a-250e. Moreover, it should be noted that a plate of a pressure attenuator may be formed in which a protrusion having the shape of the first protrusions246a-246eand/or the first protrusions312a-312dis mixed with protrusions having a polygonal shape. For example, a plate of a pressure attenuator may be formed such that each protrusion of the plate has a unique polygonal shape. In this example, the first protrusions312a-312dface the second protrusions316a-316dand are offset or misaligned from the second protrusions316a-316dalong the longitudinal axis L. With reference toFIG.7, by spacing the terminal end314,318of the first protrusions312a-312dand the second protrusions316a-316d, respectively, from the corresponding one of the first surface302aand the third surface304aand misaligning the first protrusions312a-312dfrom the second protrusions316a-316d, the undulating tortuous path256for the exhaust gases108(FIG.1) is defined between the first protrusions312a-312dand the second protrusions316a-316dalong the longitudinal axis L. The tortuous path256extends radially from the inlet defined by the bore254to an outer perimeter or circumference320of the first plate302. The outer circumference320of the first plate302defines an outlet322about the outer circumference320for the exhaust gases108to enter into the forward chamber208(FIG.3). The tortuous path256results in pressure loss for the exhaust gases108(FIG.1), which has to make sharp turns to pass between gaps257defined between the respective terminal end314,318and the respective first surface302aand third surface304a. It should be noted that while the terminal end314,318is illustrated herein as being smooth, the terminal end314,318of one or more of the first protrusions312a-312dand the second protrusions316a-316dmay be serrated, scalloped, or have a different shape. The first plate302and the second plate304are each composed of metal or metal alloy, and may be stamped, cast, machined, additively manufactured, etc. The first plate302and the second plate304may be stamped with grooves for the first protrusions312a-312dand the second protrusions316a-316d, respectively, and the first protrusions312a-312dand the second protrusions316a-316dmay be separately formed, via stamping, for example, and fixedly coupled to the grooves of the respective first plate302and the second plate304via welding or brazing, for example. Optionally, one or more pins may be employed to couple the first plate302to the second plate304to maintain the gap257between the first plate302and the second plate304. It should be noted that in other embodiments, the first plate240and the second plate242of the pressure attenuator206for the muffler200may be configured differently to define the tortuous path256to reduce pressure and velocity of incoming airflow. For example, with reference toFIG.10, a front view of a first plate400is shown and inFIG.11, a front view of a second plate402is shown. As the first plate400and the second plate402include components that are the same or similar to components of the first plate240and the second plate242of the pressure attenuator206discussed with regard toFIGS.1-6, the same reference numerals will be used to denote the same or similar components. The first plate400and the second plate402extend radially within the housing202. It should be noted that the housing202may be modified, if desired, to accommodate the shape of the first plate400and the second plate402. In one example, the first plate400is opposite the second plate402to define a pressure attenuator. In this example, each of the first plate400and the second plate402are substantially kidney-shaped, and extend along a plate longitudinal axis PL. With reference toFIG.10, the first plate400includes at least a pair of nested protrusions, and in this example, the first plate400includes four first protrusions410a-410d. The first protrusions410a-410dare nested relative to each other about an axis A400of the first plate400and the second plate402(FIG.11), and are substantially evenly spaced along a first surface400aof the first plate400. It should be noted that the first protrusions410a-410dmay be arranged in other patterns on the first plate400and may not be evenly spaced. Each of the first protrusions410a-410dextend axially from the first surface400aof the first plate400. The first surface400ais opposite a second surface400b. In this example, each of the first protrusions410a-410dare planar or extend from the first surface400aalong an axis substantially parallel to the axis A400. In other examples, the first protrusions410a-410dmay extend from the first surface400aat an angle so as to extend along an axis oblique to the axis A400. Each of the first protrusions410a-410dhave an end coupled to the first surface400a, and an opposite end or terminal end412. When assembled opposite the second plate402, the terminal end412of each of the first protrusions410a-410dis spaced apart from a third surface402aof the second plate402(FIG.11). With reference toFIG.11, the second plate402includes at least a pair of nested protrusions, and in this example, the second plate402includes four second protrusions414a-414d. The second protrusions414a-414dare nested relative to each other about an axis A400of the first plate400and the second plate402, and are substantially evenly spaced along the third surface402aof the second plate402. It should be noted that the second protrusions414a-414dmay be arranged in other patterns on the second plate402and may not be evenly spaced. Each of the second protrusions414a-414dextend axially from the third surface402aof the second plate402. The third surface402ais opposite a fourth surface402b. In this example, each of the second protrusions414a-414dare planar or extend from the third surface402aalong an axis substantially parallel to the axis A400. In other examples, the second protrusions414a-414dmay extend from the third surface402aat an angle so as to extend along an axis oblique to the axis A400. Each of the second protrusions414a-414dhave an end coupled to the third surface402a, and an opposite end or terminal end416. When assembled opposite the first plate400, the terminal end416of each of the second protrusions414a-414dis spaced apart from the first surface400aof the first plate400(FIG.10). In this example, the second plate402defines the bore254that forms an inlet of the pressure attenuator. The second plate402may also include the annular flange233defined about the bore254and extending outwardly from the fourth surface402bof the second plate402. In this example, the first protrusions410a-410dand the second protrusions414a-414dhave an arbitrary shape or a polygonal shape. With reference toFIGS.10and11, each of the first protrusions410a-410dand the second protrusions414a-414dhave a substantially kidney shape that encloses the volume. The volume enclosed by each of the first protrusions410a-410dand the second protrusions414a-414dis different or increases from the innermost first protrusion410aand the innermost second protrusion414ato the outermost first protrusion410dand the outermost second protrusion414d. It should be noted that the kidney shape illustrated and described herein is merely just one example of a polygonal shape that may be employed to form one or more of the first protrusions410a-410dand the second protrusions414a-414d. Other examples include, but are not limited to stars, pentagons, lobed-shapes, daisy shapes, etc. In addition, the first protrusions410a-410dand the second protrusions414a-414dmay comprise circles or ovals. In this example, the first protrusions410a-410dface the second protrusions414a-414dand are offset or misaligned from the second protrusions414a-414dso as to define the undulating tortuous path256between the first plate400and the second plate402when assembled. The tortuous path256extends radially from the inlet defined by the bore254(FIG.10) to an outer perimeter or circumference440of the first plate400(FIG.11). The outer circumference440of the first plate400defines an outlet442about the outer circumference440for the exhaust gases108to enter into the forward chamber208(FIG.3). The tortuous path256results in pressure loss for the exhaust gases108(FIG.1), which has to make sharp turns to pass between gaps257defined between the respective terminal end412,416and the respective first surface400aand third surface402awhen the first plate400is coupled to the second plate402. It should be noted that while the terminal end412,416is illustrated herein as being smooth, the terminal end412,416of one or more of the first protrusions410a-410dand the second protrusions414a-414dmay be serrated, scalloped, or have a different shape. The first plate400and the second plate402are each composed of metal or metal alloy, and may be stamped, cast, machined, additively manufactured, etc. The first plate400and the second plate402may be stamped with grooves for the first protrusions410a-410dand the second protrusions414a-414d, respectively, and the first protrusions410a-410dand the second protrusions414a-414dmay be separately formed, via stamping, for example, and fixedly coupled to the grooves of the respective first plate400and the second plate402via welding or brazing, for example. Optionally, one or more pins may be employed to couple the first plate400to the second plate402to maintain the gap257between the first plate400and the second plate402. With reference back toFIG.3, the forward chamber208is substantially frustoconical, however, the forward chamber208may have any polygonal shape, including, but not limited to cylindrical, hemispherical, etc. The forward chamber208is downstream from the pressure attenuator206and is fluidly coupled to the outlet262. The forward chamber208includes the chamber wall260, which extends from the outlet262to proximate the first housing wall222. In this example, the chamber wall260is spaced apart from the first housing wall222to define the outer chamber212between the chamber wall260and the first housing wall222. The chamber wall260is substantially hemispherical, but the chamber wall260may have any polygonal shape, including, but not limited to cylindrical, frustoconical, etc. (FIGS.5and6). The chamber wall260may be one-piece, and may be composed of metal or metal alloy and stamped, cast, machined etc. to define the forward chamber208. The chamber wall260also defines a chamber bore260a. The chamber bore260areceives the first transfer tube210to enable the first transfer tube210to direct the exhaust gases108out of the forward chamber208. The forward chamber208also includes and is fluidly coupled to a perforated tube270. The perforated tube270is composed of a metal or metal alloy, and is stamped, cast, machined, additively manufactured, etc. The perforated tube270is cylindrical and coaxial with the central axis C. Thus, the perforated tube270extends along an axis, which is coaxial with the central axis C and substantially perpendicular to the longitudinal axis L. The perforated tube270is coupled to the second surface240bof the first plate240at a first tube end270aand extends from the first plate240to the chamber wall260where a second tube end270bis coupled to the chamber wall260. The perforated tube270defines a plurality of holes or perforations272, which are spaced apart about a perimeter or circumference of the perforated tube270from the first tube end270ato proximate the second tube end270b. The perforations272enable the exhaust gases108from the forward chamber208to flow into the perforated tube270. The perforated tube270is fluidly and physically coupled to the first transfer tube210. The first transfer tube210is fluidly coupled between the forward chamber208and the outer chamber212. The first transfer tube210is composed of metal or metal alloy, and is stamped, cast, machined, additively manufactured, etc. The first transfer tube210is cylindrical, and has a solid outer wall. The first transfer tube210is fixedly coupled to the perforated tube270via welding, for example, and is coupled to the chamber wall260. The first transfer tube210has a first transfer inlet210adefined at the perforated tube270, and a first transfer outlet210bdefined at the chamber wall260(FIG.6). The first transfer tube210extends radially, along an axis substantially parallel to the longitudinal axis L, and substantially perpendicular to the central axis C. The first transfer tube210directs the exhaust gases108from the forward chamber208to the outer chamber212. The outer chamber212is defined between the chamber wall260and the first housing wall222, and between the outer circumference258of the pressure attenuator206and the second housing wall224. Thus, the outer chamber212is defined by a portion of the housing202exterior to the pressure attenuator206and the forward chamber208. Stated another way, the outer chamber212is radially and axially outboard of the forward chamber208and the pressure attenuator206. The outer chamber212is defined to extend about or circumscribe the first plate240and the second plate242, but is fluidly isolated from the pressure attenuator206. In one example, a volume of the outer chamber212is different, and less than, a volume of the forward chamber208. It should be noted that the outer chamber212, however, may have any desired volume that may be greater or less than the volume of the forward chamber208to target predetermined frequencies. The forward chamber208and the outer chamber212are each generally an expansion chamber. The dimensions of the outer chamber212may be tuned to frequencies that are not treated by the forward chamber208or the aft chamber216. The outer chamber212is fluidly coupled to the first transfer tube210and the second transfer tube214. The first transfer tube210directs the exhaust gases108into the outer chamber212, while the second transfer tube214directs the exhaust gases108into the aft chamber216. The second transfer tube214is fluidly coupled between the outer chamber212and the aft chamber216. The second transfer tube214is substantially cylindrical, and has a racetrack or oval cross-section. The second transfer tube214has a solid outer wall. In one example, with reference toFIG.6, the second transfer tube214is defined in the sub-housing215. The sub-housing215is composed of metal or metal alloy, and is stamped, cast, machined, additively manufactured, etc. The sub-housing215is generally annular, and includes a first end215aopposite a second end215b. The first end215ais circumferentially open, and is enclosed by the fourth surface242bof the second plate242(FIG.12). The sub-housing215cooperates with the second plate242to fluidly isolate the aft chamber216from the outer chamber212. The second transfer tube214is defined radially inward toward a center of the sub-housing215, but is spaced apart from the header pipe204. The second end215bof the sub-housing215may be conical such that the sub-housing215tapers from the second transfer tube214along the second end215b(FIG.12). The second end215bis substantially circumferentially enclosed, and defines a bore271. With reference toFIG.12, the bore271receives the exhaust pipe218to couple the exhaust pipe218to the muffler200. The sub-housing215is fixedly coupled to the third housing wall226via brazing or welding, for example, and the sub-housing215is coupled to the fourth surface242bof the second plate242via brazing or welding, for example. The second transfer tube214extends radially, along an axis substantially parallel to the longitudinal axis L, and substantially perpendicular to the central axis C. The second transfer tube214directs the exhaust gases108from the outer chamber212to the aft chamber216defined within the sub-housing215. The aft chamber216is defined within the sub-housing215between the second transfer tube214and the exhaust pipe218. With continued reference toFIG.12, the sub-housing215includes an aft chamber wall280, which is coupled to the fourth surface242bof the second plate242and the third housing wall226. Thus, the aft chamber216is defined between the second plate242and the third housing wall226, and is fluidly isolated from the pressure attenuator206. The aft chamber216is fluidly coupled to the second transfer tube214to receive the exhaust gases108from the outer chamber212, and is fluidly coupled to the exhaust pipe218. The exhaust pipe218is fluidly coupled to the aft chamber216and extends beyond the housing202of the muffler200to direct the exhaust gases108from the muffler200. The exhaust pipe218is composed of metal or metal alloy, and is stamped, cast, machined, additively manufactured, etc. The exhaust pipe218is cylindrical, and is solid. The exhaust pipe218is fixedly coupled to the bore271of the sub-housing215via brazing or welding, for example, and is coupled to the exhaust bore232of the third housing wall226via brazing or welding, for example. The exhaust pipe218extends axially, along an axis substantially perpendicular to the longitudinal axis L, and substantially parallel to the central axis C. The exhaust pipe218directs the exhaust gases108from the muffler200, and in one example, directs the exhaust gases108to an ambient environment surrounding the engine102(FIG.1). Alternatively, the exhaust pipe218may be fluidly coupled to a downstream secondary muffler. With reference back toFIG.3, in one example, the deswirl assembly220is defined about the second housing wall224. It should be noted that in certain embodiments, the muffler200need not include the deswirl assembly220and the deswirl assembly220may be optional. The deswirl assembly220includes an outer assembly wall290and at least one or a plurality of vanes294. The deswirl assembly220is composed of metal or metal alloy, and is cast, machined, forged, additively manufactured, etc. The outer assembly wall290is annular, and is concentric with the second housing wall224. The outer assembly wall290extends about the perimeter of the second housing wall224, and is spaced apart from the second housing wall224to define an airflow path296. The outer assembly wall290has a first wall end290aand a second wall end290b. The first wall end290ais upstream from the second wall end290b, and receives the cooling air110(FIG.1) from the cooling fan116. The outer assembly wall290is substantially planar from the first wall end290ato proximate the second wall end290b. The second wall end290bis coupled to a guide flange291. The guide flange291is annular (FIG.5), and curves radially inward from a first flange end291ato a second flange end291b. The curvature of the guide flange291directs the cooling air110along an exterior surface of the third housing wall226. The guide flange291is composed of metal or metal alloy, and is cast, stamped, machined, additively manufactured, etc. The guide flange291is coupled to the second wall end290bvia welding or brazing, for example, however, other techniques may be employed. For example, the guide flange291may be integrally formed with the outer assembly wall290. The vanes294are spaced apart about the perimeter of the second housing wall224and coupled between the second housing wall224and the outer assembly wall290. The vanes294are coupled to the second housing wall224, via brazing or welding, for example, and are coupled to the outer assembly wall290via brazing or welding, for example, or may be integrally formed with the outer assembly wall290. The vanes294extend along an axis substantially parallel to the centerline C and substantially perpendicular to the longitudinal axis L, however, in other embodiments, the vanes294may be orientated differently. With reference toFIG.4, each of the vanes294has a leading end294aand an opposite trailing end294balong the airflow path296. The leading end294ais proximate the first wall end290a, and the trailing end294bis proximate the second wall end290b. The vanes294remove tangential velocity from the cooling air110as it flows through the deswirl assembly220along the airflow path296. In one example, with reference toFIG.3, with the first protrusions246a-246ecoupled to the first plate240, the second protrusions250a-250ecoupled to the second plate242and the second housing wall224formed, the first plate240is spaced apart from the second plate242coupled to the second housing wall224to define the gap257(FIG.4). Alternatively, with the first protrusions312a-312dcoupled to the first plate302, the second protrusions316a-316dcoupled to the second plate304and the second housing wall224formed, the first plate302is spaced apart from the second plate304coupled to the second housing wall224to define the gap257(FIGS.7-9). As a further alternative, with the first protrusions410a-410dcoupled to the first plate400, the second protrusions414a-414dcoupled to the second plate402and the second housing wall224formed, the first plate400is spaced apart from the second plate402coupled to the second housing wall224to define the gap257(FIGS.10and11). The header pipe204is positioned through the sub-housing215and coupled to the second plate242. With the chamber wall260, the perforated tube270and the first transfer tube210formed, the perforated tube270is coupled to the first transfer tube210, via welding, brazing, etc. The chamber wall260is positioned about the perforated tube270and the first transfer tube210is inserted through the chamber bore260aof the chamber wall260. The chamber wall260is coupled to the second plate242via welding, brazing, etc. The first housing wall222is coupled to the second housing wall224via welding, brazing, etc. to form a seal. With the second transfer tube214defined in the sub-housing215, the sub-housing215is coupled to the second plate242via welding, brazing, etc. to form a seal. The third housing wall226is coupled to the sub-housing215via welding, brazing, etc. to form a seal. The vanes294of the deswirl assembly220are coupled to the second housing wall224, and the outer assembly wall290is coupled to the vanes294. The guide flange291is coupled to the outer assembly wall290via welding, brazing, etc. With the muffler200assembled, the muffler200is fluidly coupled to the engine102(FIG.1). In one example, the header pipe204is fluidly coupled to an exhaust manifold associated with the engine102(FIG.1) to receive the exhaust gases108. The deswirl assembly220is placed in fluid communication with the cooling fan116to receive the cooling air110(FIG.1). During operation of the engine102, such as the Wankel engine, the exhaust gases108have high energy. The exhaust gases108flow from the engine102through the header pipe204into the pressure attenuator206. The exhaust gases108flow radially through the tortuous path256and exit the pressure attenuator206at the outer circumference258of the first plate240into the forward chamber208. It should be noted that the gap257may be adjusted (increased or decreased) by moving the first plate240and/or the second plate242if desired based on the operating characteristics of the engine102(FIG.1). The exhaust gases108expand in the forward chamber208, and flow into the perforated tube270. The exhaust gases108flow from the perforated tube270into the first transfer tube210. The first transfer tube210directs the exhaust gases108into the outer chamber212. From the outer chamber212, the exhaust gases108flow through the second transfer tube214to the aft chamber216. From the aft chamber216, the exhaust gases108flow into the exhaust pipe218where the exhaust gases108are directed external to the muffler200. The cooling air110received by the deswirl assembly220provides cooling to the muffler200during the operation of the engine102(FIG.1). Thus, the muffler200receives the high-energy exhaust gases108from the engine102(FIG.1) and reduces the pressure of the exhaust gases without generating excessive velocity with the pressure attenuator206, which limits noise generation. The forward chamber208and the outer chamber212cooperate as expansion chambers to attenuate the sound generated by the exhaust gases. The compact size of the muffler200enables the muffler200to be used within the power unit104and the muffler200may be positioned within the housing120of the power unit104. In addition, the integration of the deswirl assembly220with the muffler200reduces components associated with the power unit104. It should be noted that while the pressure attenuator206is described herein as circular having the first plate240and second plate242with a circular shape, the pressure attenuator300is described herein as D-shaped having the first plate302and second plate304with the D-shape; the pressure attenuator having the first plate400and the second plate402having the kidney shape, a pressure attenuator and the associated plates for use with the muffler200may have any desired shape, including, but not limited to, kidney shaped, D-shaped, circular, oval, polygonal, etc. Thus, the shapes of the plates240,242,302,304,400,402is merely an example. Moreover, as discussed, the shapes of the first protrusions246a-246e, the second protrusions250a-250e, the first protrusions312a-312d, the second protrusions316a-316d, the first protrusions410a-410dand the second protrusions414a-414dare merely an example, as the first protrusions246a-246e, the second protrusions250a-250e, the first protrusions312a-312d, the second protrusions316a-316d, the first protrusions410a-410dand the second protrusions414a-414dmay have any polygonal shape. Moreover, each of the plates240,242,302,304,400,402may have any number of the first protrusions246, the second protrusions250, the first protrusions312, the second protrusions316, the first protrusions410and the second protrusions414and the shape of the first protrusions246, the second protrusions250, the first protrusions312, the second protrusions316, the first protrusions410and the second protrusions414may vary along the respective plate240,242,302,304,400,402such that the first protrusions246, the second protrusions250, the first protrusions312, the second protrusions316, the first protrusions410and the second protrusions414aassociated with the particular plate240,242,302,304,400,402need not have the same shape. In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Numerical ordinals such as “first,” “second,” “third,” etc. simply denote different singles of a plurality and do not imply any order or sequence unless specifically defined by the claim language. The sequence of the text in any of the claims does not imply that process steps must be performed in a temporal or logical order according to such sequence unless it is specifically defined by the language of the claim. The process steps may be interchanged in any order without departing from the scope of the invention as long as such an interchange does not contradict the claim language and is not logically nonsensical. While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the disclosure as set forth in the appended claims and the legal equivalents thereof. | 50,800 |
11859524 | It may be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the present invention. The specific design features of the present invention as included herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particularly intended application and use environment. In the figures, reference numbers refer to a same or equivalent portions of the present invention throughout the several figures of the drawing. DETAILED DESCRIPTION Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the present invention(s) will be described in conjunction with exemplary embodiments of the present invention, it will be understood that the present description is not intended to limit the present invention(s) to those exemplary embodiments. On another hand, the present invention(s) is/are intended to cover not only the exemplary embodiments of the present invention, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the present invention as defined by the appended claims. Hereinafter, various exemplary embodiments of the present invention will be described in detail with reference to the accompanying exemplary drawings, and these exemplary embodiments may be implemented in various different forms by those skilled in the art to which various exemplary embodiments of the present invention pertains as an example, and thus are not limited to the exemplary embodiments described herein. FIGS.1,2A and2Billustrate a method for interlocking an engine exhaust sound with a vehicle traveling mode implemented by a vehicle exhaust system. Referring toFIG.1, a method for interlocking an engine exhaust sound with a vehicle traveling mode implements a SMART SHIFT control (S40, S50-1, S50-2, S50-3, S60-1, S60-2) which automatically switches an exhaust sound from a sporty exhaust sound to a quiet exhaust sound or from the quiet exhaust sound to the sporty exhaust sound based on an accelerator pedal stroke in a SMART DRIVE MODE (S10, S20) after a vehicle is started-up (ON). As illustrated inFIG.2AandFIG.2B, a method for interlocking an engine exhaust sound with a vehicle traveling mode exemplarily provides that a control thereof is implemented by a logic or program hierarchy structure so that the SMART DRIVE MODE (S10, S20) provides a SMART DRIVE MODE using a mode selection device1B-1(seeFIG.3). The SMART SHIFT control (S40, S50-1, S50-2, S50-3, S60-1, S60-2) is classified into a SMART DRIVE MODE automatic switching control (S40, S50-1, S50-2, S50-3) and a switching mode exhaust sound matching control (S60-1, S60-2). As an example, the SMART DRIVE MODE automatic switching control (S40, S50-1, S50-2, S50-3) selects, as the SMART DRIVE MODE, any one of a SMART DRIVE MODE-ECO state, a SMART DRIVE MODE-COMFORT state, and a SMART DRIVE MODE-SPORT state based on an accelerator pedal stroke. Furthermore, the switching mode exhaust sound matching control (S60-1, S60-2) generates an exhaust sound by switching a sporty exhaust sound-based map54-1B in the SMART DRIVE MODE-SPORT state and a quiet exhaust sound-based map54-1A in the SMART DRIVE MODE-ECO state/the SMART DRIVE MODE-COMFORT state therebetween with respect to the SMART DRIVE MODE-ECO state, the SMART DRIVE MODE-COMFORT state, and the SMART DRIVE MODE-SPORT state, which are changed during traveling of a vehicle. In the instant case, the change in the engine exhaust sound is performed by an electronic variable valve30(seeFIG.4,FIG.5,FIG.6,FIG.7, andFIG.8) for varying the flow rate of the exhaust gas, which will be described later. Therefore, the method for interlocking the engine exhaust sound with the traveling mode may implement the feature in which the exhaust sounds of left/right mufflers20-1,20-2interlocked with the electronic variable valve30may be generated in the SMART SHIFT control, automatically changing the engine exhaust sound even without the driver's mode operation. Meanwhile,FIG.3,FIG.4,FIG.5,FIG.6andFIG.7illustrate an example of implementing an exhaust sound change system1-2applied to an exhaust system1-1for a vehicle1in which the method for interlocking the engine exhaust sound with the traveling mode is implemented. Referring toFIG.3, the engine exhaust sound change system1-2drives an actuator (or a DC motor) of the electronic variable valve30by confirming an engine revolutions per minute (RPM), an accelerator pedal stroke (APS), and an engine torque among vehicle sensor signals of the vehicle1from an input condition logic40in a mode recognition logic50, and then transferring a voltage signal of 9 to 16 V as a motor application voltage to an output driving logic60based on the accelerator pedal stroke. Hereinafter, the mode recognition logic50is actually implemented by a controller, a processor, or a central processing unit having a memory for storing a logic or a program but for convenience of explanation, will be described by a control logic or a program which is configured to perform the method for interlocking the engine exhaust sound with the traveling mode. The mode recognition logic50includes: a communication processor51, a mode processor52, an accelerator pedal signal processor53, and a variable valve operation map54. In the instant case, the processor may be a processor having the memory for storing a logic or a program performing a control to execute the logic. As an example, the communication processor51confirms the input conditions of the engine RPM, the accelerator pedal stroke, and the engine torque from the logic40. The mode processor52confirms when the SMART DRIVE MODE has been selected from the mode selection device1B-1of a traveling mode system1B. The accelerator pedal signal processor53is configured to perform the SMART SHIFT control by confirming the accelerator pedal stroke condition in the SMART DRIVE MODE. In the SMART SHIFT control, the following mode enters according to the accelerator pedal stroke condition. [Below]SMART DRIVE MODE-SPORT state: accelerator pedal stroke (APS)>25 to 30%SMART DRIVE MODE-ECO state: accelerator pedal stroke (APS)<5 to 10%SMART DRIVE MODE-COMFORT state: accelerator pedal stroke (APS)>5 to 10% Therefore, the SMART DRIVE MODE automatically switches the engine exhaust sound while the state is switched according to a change in the accelerator pedal stroke as in the SMART DRIVE MODE-ECO state↔the SMART DRIVE MODE-COMFORT state↔the SMART DRIVE MODE-SPORT state in the SMART SHIFT control depending on the accelerator pedal stroke. As an example, the variable valve operation map54is classified into the quiet exhaust sound-based map54-1A in which the engine exhaust sound is matched according to the SMART DRIVE MODE-ECO state and the SMART DRIVE MODE-COMFORT state, and the sporty exhaust sound-based map54-1B in which the engine exhaust sound depending on the SMART DRIVE MODE-SPORT state is matched. In the instant case, the quiet exhaust sound-based map54-1A and the sporty exhaust sound-based map54-1B will be described in detail later with reference toFIG.8. Furthermore, when the mode selection device113-1of the traveling mode system1B is recognized through an engine electronic control unit (ECU)1A for transmitting data to the mode recognition logic50, the engine exhaust sound change system1-2is driven by sending a voltage signal to the electronic variable valve via pulse width modulation (PWM) communication. As an example, the traveling mode system1B provides the feature expressed in Table 1 with respect to the SMART DRIVE MODE selected by the mode selection device1B-1. TABLE 1Customer's driving tendencySporty indexEXTRAMILDNORMALSPORTYEXTRAMILDSPORTY0%100%Automatic switching←→TravelingSMARTSMARTSMART SPORTmodeECOCOMFORTphase 3ShiftHighFuelStandardAccelerationRapidpatternfuelefficiencytypetypeturningphase 5efficiencytypetypetypeEngineFuel efficiency typeStandardResponsive typetorquetypephase 3CoastingOperationNon-operationneutral(intelligence type)controlSuspensionSoftHardphase 2 Therefore, the SMART DRIVE MODE may reflect the driving tendency and habit by setting three types of the SMART DRIVE MODE-ECO state, the SMART DRIVE MODE-COMFORT state, and the SMART DRIVE MODE-SPORT state as a sub mode, and automatically switch the mode such as the SMART DRIVE MODE-ECO state↔the SMART DRIVE MODE-COMFORT state↔the SMART DRIVE MODE-SPORT state in the SMART SHIFT control depending on the accelerator pedal stroke without the driver's intervention or selection. As an example, through the SMART SHIFT control, the SMART DRIVE MODE may 1) determine the long-term habit and momentary intention of the driver, changing not only a shift time point but also riding comfort by adjusting an attenuation force depending on the traveling mode of an electronic controlled suspension (ECS) interlocked with the engine output, and 2) interlock the actually physical exhaust sound with the traveling quality and the traveling mode, providing the differentiated exhaust sound without the driver's operation. Referring toFIG.4, the vehicle1includes: the exhaust system1-1controlled by the engine exhaust sound change system1-2to vary the exhaust sound. As an example, the exhaust system1-1includes: an exhaust line10through which the exhaust gas generated by the combustion of an engine flows, a muffler20including a left muffler20-1and a right muffler20-2provided on the edge portion of the exhaust line10to discharge the exhaust gas to the outside and the electronic variable valve30mounted on the exhaust gas outlets (see first and second tail pipes28,29illustrated inFIG.2AandFIG.2B) of each of the left/right mufflers20-1,20-2. Therefore, the exhaust system1-1is characterized as an exhaust system for a smart vehicle. The exhaust line10is classified into an engine side exhaust pipe10A, an intermediate exhaust pipe10B, and a muffler side exhaust pipe10C connected to one another, and each of the engine side exhaust pipe10A, the intermediate exhaust pipe10B, and the muffler side exhaust pipe10C forms a layout as a double pipe structure configuring a pair of two pipes. Therefore, the left muffler20-1of the left/right mufflers20-1,20-2is mounted on one pipe of two pipes of the muffler side exhaust pipe10C, and the right muffler20-2is mounted on another pipe of two pipes of the muffler side exhaust pipe10C. Furthermore, the electronic variable valve30is provided on each of the left muffler20-1and the right muffler20-2, and the installation location of each of the left muffler20-1and the right muffler20-2is applied to a first tail pipe28(e.g., seeFIG.5) of the first and second tail pipes28,29through which the exhaust gas is discharged from each of the left muffler20-1and the right muffler20-2. The electronic variable valve30is controlled by an engine exhaust sound change signal output from the mode recognition logic50of the engine exhaust sound change system1-2. Meanwhile,FIG.5,FIG.6andFIG.7illustrate detailed configurations of the left muffler20-1, the right muffler20-2, and the electronic variable valve30. Referring toFIG.5andFIG.6, each of the left muffler20-1and the right muffler20-2includes: a housing21, a baffle22, an inlet tube23, a 1IN-2OUT Y-shaped tube24,25,26, a second external connection tube27, the first tail pipe28, and the second tail pipe29as components of the muffler, and the electronic variable valve30includes: a valve driving device31and a valve gate33as components of the valve. Therefore, hereinafter, the components of the muffler will be described without distinction between the left muffler20-1and the right muffler20-2, and the components of the valve will be described without distinction between the electronic variable valve30applied to the left muffler20-1and the electronic variable valve30applied to the right muffler20-2. The housing21includes: a housing body21A forming an internal space by closing one portion (i.e., the upper portion of the housing body21A) with an upper plate21B and closing another portion (i.e., the lower portion of the housing body21A) with a lower plate21C. In the instant case, the upper portion of the housing body21A means a direction in which the exhaust gas is introduced into the housing21, and the lower portion of the housing body21A means a direction in which the exhaust gas is discharged from the housing21. The upper plate21B presses the housing21to form an upper expansion space portion21B-1protruding outward, and the lower plate21C presses the housing21to form a lower expansion space portion21C-1protruding outward. Therefore, each of the upper expansion space portion21B-1and the lower expansion space portion21C-1expands an internal space volume of the housing21. The baffle22includes: a pair of a first baffle22A and a second baffle22B to partition the internal space of the housing21. That is, the first and second baffles22A,22B partition the internal space of the housing21into a first chamber21-1in which the first baffle22A and the upper plate21B face each other, a second chamber21-2, in which the first baffle22A and the second baffle22B face each other, and a third chamber21-3, in which the second baffle22B and the lower expansion space portion21C-1face each other. To, the present end, the first baffle22A is coupled to the inlet tube23by one tube hole22-1of two perforated tube holes22-1,22-2and coupled to the second external connection tube27by another tube hole22-2thereof. Furthermore, the second baffle22B is coupled to an extension tube26by one perforated tube hole22-3. The first baffle22A perforates the peripheries of the tube holes22-1,22-2using a punching hole22-5having a small diameter as a punching hole group, forming a fine passage through which a portion of the exhaust gases is discharged from the first chamber21-1to the second chamber21-2. On another hand, the second baffle22B forms a pair of a first open space portion22-6, which is a space through which the first external connection tube25passes, and a second open space portion22-7, which is a space through which the second external connection tube27passes, forming an opening passage through which a portion of the exhaust gases is discharged from the second chamber21-2to the third chamber21-3. The inlet tube23is fixed to the hole of the upper plate21B in a state of being coupled to the tube hole22-1of the first baffle22A and thus connected to the muffler side exhaust pipe10C outside the housing21, and operates as a gas inlet into which the exhaust gas flowing to the muffler side exhaust pipe10C is introduced. The inlet tube23perforates the circumference of the circle using a punching hole23A having a small diameter as a punching hole group in an intermediate section, sending the exhaust gas to a branch tube24and sending a portion of the exhaust gases to the first chamber21-1. The 1IN-2OUT Y-shaped tube24,25,26includes: the branch tube24, the first external connection tube25, and the extension tube26. As an example, the branch tube24is formed in an “inverse Y” shape to branch the exhaust gas introduced in a direction through one inlet into two directions through two outlets and send the exhaust gas. That is, the branch tube24connects one inlet (i.e., 1IN) to the inlet tube23to introduce the exhaust gas, and connects two outlets (i.e., 2OUT) to the first external connection tube25and the extension tube26, respectively to send the exhaust gas. The first external connection tube25is formed in an elbow pipe shape having a smoothly curved bending structure, and thus fitted into a hole of the lower plate21C through the first open space portion22-6of the second baffle22B at a location of the branch tube24, and connected to the first tail pipe28outside the housing21to form a valve interference path. In the instant case, the valve interference path forms a first exhaust sound tone change section X (seeFIG.9) with respect to the exhaust gas discharged to the first tail pipe28. On another hand, the extension tube26is formed in a substantially straight pipe shape, forming a tube separation interval with the expansion space portion21C-1of the lower plate21C through the tube hole22-3of the second baffle22B at a location of the branch tube24. In the instant case, the tube separation interval forms a third exhaust sound tone change section Z (seeFIG.9) with respect to the exhaust gas diffused into the muffler. Furthermore, the first external connection tube25and the extension tube26are press-fitted and coupled to the branch tube24or coupled to the branch tube24by welding to be integrated. The second external connection tube27is formed in a straight pipe shape, has another end portion fitted into the hole of the lower plate21C through the second open space portion22-7of the second baffle22B in a state of having one end portion fitted into the tube hole22-2of the first baffle22A, and is connected to the second gas discharge tube29outside the housing21. The second external connection tube27perforates the circumference of the circle using a punching hole27A having a small diameter as a punching hole group in an edge portion section to send the exhaust gas to the second gas discharge tube29and send a portion of the exhaust gases to the third chamber21-3, forming a hole interference path. In the instant case, the hole interference path forms a second exhaust sound tone change section Y (seeFIG.9) with respect to the exhaust gas discharged to the second gas discharge tube29. Furthermore, the second external connection tube27is surrounded by a double tube27-1having a short length not covering the punching hole27A. In the instant case, the double tube27-1is made of a same material as the second external connection tube27or may also employ a foam mat having an excellent thermal resistance. Referring toFIG.7, the electronic variable valve30includes: the valve driving device31driven by an engine exhaust sound change signal of the output driving logic60connected to the mode recognition logic50, and a valve gate33for changing a valve opening by operation of the valve driving device31. To, the present end, the valve driving device31includes: an electric control board for controlling an electric signal, a power source using an actuator, a motor side rod (e.g., screw) for converting rotation into a linear motion, a gear mechanism (e.g., worm gear and gear wheel) for converting a linear motion into rotation, a housing, and the like therein, and the valve gate33is located outside the housing of the valve driving device31to change a valve stroke with a rotational angle of a circular rotation plate receiving the rotation of an actuator or a motor toward the valve. In the instant case, the electric circuit board, the actuator, the motor side rod, the gear mechanism, the housing, and the like are general components of the electronic variable valve30. As an example, if the electronic variable valve30employs the DC motor as the actuator, the DC motor is driven by use of an engine exhaust sound change signal of 9 to 16V as the motor application voltage, the motor side rod (e.g., screw) converts the motor rotation into a linear motion and then converts the linear motion into the rotation of the gear wheel through the worm gear, and the rotation of the gear wheel rotates the valve gate33coupled to the gear wheel so that the cross-sectional area of the exhaust gas passage of the first tail pipe28is changed by the valve opening of closing (0% opening)↔50% opening↔100% opening. Hereinafter, the method for interlocking the engine exhaust sound with the traveling mode illustrated inFIG.1will be described in detail with reference toFIGS.8A to12. In the instant case, the control subject is the engine ECU1A configuring the engine exhaust sound change system1-2or the mode recognition logic50interlocked therewith, and the control object is the electronic variable valve30. Referring toFIG.1, the engine ECU1A is configured to perform recognizing start ON (S10), selecting a vehicle traveling mode (S20), and confirming a SMART DRIVE MODE (S30). Referring toFIG.3, the mode recognition logic50is connected to the engine ECU1A to utilize the communication processor51and the mode processor52. As an example, the mode processor52reads an IG_Key ON, which is a start detection signal of the engine ECU1A transmitted to the input condition logic40through the communication processor51. Furthermore, the mode processor52reads the engine RPM, the accelerator pedal stroke, and the engine torque among the vehicle speed, engine load, engine coolant temperature, engine RPM, accelerator pedal stroke, and engine torque of the engine ECU1A transmitted to the input condition logic40through the communication processor51. Furthermore, the mode processor52recognizes a selection signal of the SMART DRIVE MODE generated by the mode selection device1B-1of the traveling mode system1B transmitted to the input condition logic40through the engine ECU1A. Therefore, the mode recognition logic50confirms the engine start (S10) with the start ON of the IG_Key ON, and is configured to perform the confirming of the SMART DRIVE MODE (S20, S30) through the mode selection device1B-1. As a result, the mode recognition logic50recognizes the current traveling state of the vehicle1as the SMART DRIVE MODE (S30) and switches the traveling state to the SMART SHIFT control (S40, S50-1, S50-2, S50-3, S60-1, S60-2). Next, the mode recognition logic50is configured to perform the SMART SHIFT control (S40, S50-1, S50-2, S50-3, S60-1, S60-2) as the SMART DRIVE MODE automatic switching control (S40, S50-1, S50-2, S50-3) and the switching mode exhaust sound matching control (S60-1, S60-2). As an example, the SMART DRIVE MODE automatic switching control (S40, S50-1, S50-2, S50-3) includes: confirming the accelerator pedal stroke (S40), entering the SMART DRIVE MODE-SPORT state (S50-1), entering the SMART DRIVE MODE-ECO state (S50-2), and entering the SMART DRIVE MODE-COMFORT state (S50-3). The mode recognition logic50applies the following equation to the confirming of the accelerator pedal stroke (S40) through the accelerator pedal processor53. Equation to which the sport exhaust sound is applied: A>α? Equation to which the quiet exhaust sound is applied: A<β? where “A” refers to an accelerator pedal stroke detection value, “α” refers to a first threshold of the accelerator pedal stroke and applies the APS of about 25 to 30%, whereas “β” refers to a second threshold of the accelerator pedal stroke and applies the APS of about 5 to 10%, and “>” refers to an inequality sign indicating the size relationship between two values. Referring toFIG.3, the mode recognition logic50confirms whether the accelerator pedal stroke detection value A is a value larger or smaller than the first threshold (a) of the accelerator pedal stroke, and confirms whether the accelerator pedal stroke detection value A is a value larger or smaller than the second threshold (0) of the accelerator pedal stroke through the accelerator pedal processor53. As a result, the mode recognition logic50enters the SMART DRIVE MODE-SPORT state (S50-1) if the condition of the “A>α” is satisfied, and enters the SMART DRIVE MODE-ECO state (S50-2) if the condition of the “A<β” is satisfied, whereas the mode recognition logic50enters the SMART DRIVE MODE-COMFORT state (S50-3) if the condition is not satisfied (i.e., A>β). As an example, the switching mode exhaust sound matching control (S60-1, S60-2) includes: generating a sporty exhaust sound-based map applied exhaust sound for the SMART DRIVE MODE-SPORT state (S60-1), and generating a quiet exhaust sound-based map applied exhaust sound for the SMART DRIVE MODE-ECO state and the SMART DRIVE MODE-COMFORT state (S60-2). Furthermore, the mode recognition logic50receives a change value of the accelerator pedal stroke detected by the engine ECU1A through the input condition logic40to continuously process the change value in the accelerator pedal processor53. Accordingly, each of the sporty exhaust sound-based map54-1B and the quiet10exhaust sound-based map54-1A automatically matches with closing (0% opening)↔50% opening↔100% opening depending on the change in the accelerator pedal stroke in a line diagram of engine torque-engine RPM so that the valve opening of the electronic variable valve30is automatically changed according to the change in the accelerator pedal stroke. Meanwhile,FIGS.8A,8B and8C to12illustrate an example of the change in the flow of the exhaust gas of the muffler20according to the change in the valve opening of the electronic variable valve30and generating the quiet exhaust sound and the sporty exhaust sound generated by the change in the flow of the exhaust gas. FIG.8A,FIG.8BandFIG.8Cillustrate that the valve opening of the electronic variable valve30is changed to any one of the closing (0% opening), the 50% opening, and the 100% opening in an engine torque area of 0 to 100% and an engine RPM area of 0 to 7000 RPM of the quiet exhaust sound-based map54-1A and the sporty exhaust sound-based map54-1B, and automatically changed such as closing (0% opening)↔50% opening↔100% opening according to the change in the accelerator pedal stroke. As an example, in the case of the quiet exhaust sound-based map54-4A, in the engine torque area of 0 to 100% and the engine RPM area of 0 to 7000 RPM of the quiet exhaust sound-based map54-1A, the electronic variable valve30applies the closing (0% opening) to a section A and a section C, applies the 50% opening to a section B and a section D, and applies the 100% opening to a section E. The section A is a section in which the engine torque in an area equal to or smaller than about 20% is matched with the engine RPM in an area equal to or smaller than 4600 RPM and the engine torque in an area equal to or smaller than about 10% with the engine RPM in an area (i.e., the entire area) equal to or smaller than 7600 RPM, and the section C is a section matching the engine torque in an area of about 20 to 100% with the engine RPM in an area of about 1050 to 2600 RPM and the engine torque in an area of about 20 to 40% with the engine RPM in an area of about 1050 to 4600 RPM. Furthermore, the section B is a section matching the engine torque in an area of about 20 to 30% with the engine RPM in an area equal to or smaller than about 1050 RPM, and the section D is a section matching the engine torque in an area of about 10 to 30% with the engine RPM in an area of about 4600 to 5400 RPM. Furthermore, the section E is a section matching the engine torque in an area of about 10 to 30% with the engine RPM in an area of about 5400 to 7000 RPM, the engine torque in an area of about 30 to 50% with the engine RPM in an area of about 4600 to 7000 RPM, and the engine torque in an area of about 50 to 100% with the engine RPM in an area of about 2600 to 7000 RPM. Therefore, in each of the sections A, B, C, D, E, the exhaust sounds of the left/right mufflers20-1,20-2are generated depending on the SMART DRIVE MODE-ECO state and the SMART DRIVE MODE-COMFORT state (S60-2) with the closing (0% opening), 50% opening, 100% opening of the electronic variable valve30according to the application of the quiet exhaust sound-based map. On another hand, in the case of the sporty exhaust sound-based map54-1B, the electronic variable valve30applies any one of the closing (0% opening), the 50% opening, and the 100% opening in the engine torque area of 0 to 100% and the engine RPM area of 0 to 7000 RPM in the sporty exhaust sound-based map54-1B. That is, the closing (0% opening) is applied to a section F and a section J in the engine torque-engine RPM line diagram, the 50% opening is applied to a section G and a section H, and the 100% opening is applied to a section I and a section K. The section F is a section matching the engine torque in an area equal to or smaller than about 20% with the engine RPM in an area of about 1050 to 6200 RPM, and the section J is a section matching the engine torque in an area of about 65 to 100% with the engine RPM in an area of about 1050 to 2500 RPM. Furthermore, the section G is a section matching the engine torque in the area of about 20% or less with the engine RPM in an area of about 6200 to 7000 RPM, and the section H is a section matching the engine torque in an area equal to or smaller than about 65% with the engine RPM in an area equal to or smaller than about 1050 RPM, the engine torque in an area of about 20 to 65% with the engine RPM in an area of about 1050 to 2200 RPM, and the engine torque in an area of about 20 to 55% with the engine RPM in an area of about 2200 to 5600 RPM. Furthermore, the section I is a section matching the engine torque in an area of about 65 to 100% with the engine RPM in an area equal to or smaller than about 1050 RPM, and the section K is a section matching the engine torque in an area of about 20 to 50% with the engine RPM in an area of about 5500 to 7000 RPM, and the engine torque in an area of about 50 to 100% with the engine RPM in an area of about 2200 to 7000 RPM. Therefore, in each of the sections F, G, H, I, K, the exhaust sounds of the left/right mufflers20-1,20-2are generated depending on the SMART DRIVE MODE-SPORT state (S60-1) with the closing (0% opening), 50% opening, 100% opening of the electronic variable valve30according to the application of the sporty exhaust sound-based map. Subsequently,FIG.9,FIG.10andFIG.11illustrate an example in which the left/right mufflers20-1,20-2differently generate the exhaust sounds in each of the closing (0% opening), the 50% opening, and the 100% opening of the valve gate33through the driving of the electronic variable valve (S90). In the instant case, each of the left/right mufflers20-1,20-2has a same configurations and effects, and thus will be referred to as the muffler20. Furthermore, the solid-lined/dotted-lined arrows mean the flow state of the exhaust gas and the wave shape means the diffusion and propagation state of the exhaust gas. InFIGS.9to11, the valve gate33of the electronic variable valve30closes the internal cross section of the first tail pipe28of the two first and second tail pipes28,29(e.g., closing (0% opening)), opens a half of the internal cross section thereof (e.g., 50% opening), or fully opens the internal cross section thereof (e.g., 100% opening) so that a portion in which the emission of the exhaust gas is varied according to the change in the area of the internal flow field of the first tail pipe29with the emission of the exhaust gas maintained through the second tail pipe29in the muffler20has been illustrated. Therefore, the muffler20forms a basic flow of the exhaust gas which utilizes the inlet tube23→the branch tube24→the extension tube26→the second external connection tube27→the second tail pipe29as the flow path, and a variable flow of the exhaust gas which utilizes the inlet tube23→the branch tube24→the first external connection tube25→the first tail pipe28as the flow path. Therefore, with respect to the closing (0% opening) applied to the sections A, C, F, J illustrated inFIG.9, the 100% opening applied to the sections E, I, K illustrated inFIG.10, and the 50% opening applied to the sections B, D, G, H illustrated inFIG.11, the basic flows of the exhaust gases are a same whereas the variable flows of the exhaust gases are different. As an example, describing the basic flow of the exhaust gas with reference toFIGS.9to11, the muffler20forms the flow path in which the exhaust gas is mostly collected in the first chamber21-1through the punching hole23A (e.g., the number of punches is 84EA) of the inlet tube23, the exhaust gas coming through the punching hole27A of the second external connection tube27together with the exhaust gas coming from the extension tube26of the branch tube24and reflected by the lower plate21C is discharged from the third chamber21-3to the second chamber21-2and introduced into the first chamber21-1through the punching hole22-5(e.g., the number of punches is 60EA) of the first baffle22A, and the exhaust gas introduced into the first chamber21-1is discharged to the second tail pipe29through the second external connection tube27. The muffler20distributes/cancels a unpleasant low-frequency booming sound energy, which presses the driver's ears, by the expansion/diffusion of the flow rate of the exhaust gas through the punching holes23A,27A,22-5and the first, second, third chambers21-1,21-2,21-3, reducing some amount of noise energy, and the punching hole27A reduces an airflow sound component once again so that the engine exhaust sound having further reduced some amount of noise energy may be discharged. Describing the variable flow of the exhaust gas with reference to the closing (0% opening) applied to the sections A, C, F, J illustrated inFIG.9, the valve gate33of the electronic variable valve30closes the internal area of the first tail pipe28, preventing the exhaust gas introduced into the first external connection tube25of the muffler20from being discharged to the atmosphere. Therefore, the muffler20discharges the exhaust gas introduced into the inlet tube23to only the second tail pipe29in a state in which the first tail pipe28of the two first and second tail pipes28,29is closed, theoretically reducing the entire area at which the flow rate of the exhaust gas is discharged by 50%. The condition of reducing the flow rate or cross-sectional area of the exhaust gas discharged from the exhaust system1-1to the atmosphere is a same as the condition of reducing the diameter of the tail pipe through which the exhaust gas is discharged in the structure of the general exhaust system. Such a valve operation condition is optimized mostly in an idle driving area or a low RPM driving area, which has a basic flow rate of the exhaust gas much smaller than the basic flow rate of the exhaust gas upon the 100% opening of the valve. Therefore, the muffler20forms the first exhaust sound tone change section X (seeFIG.9) closed by the first external connection tube25, the first tail pipe28, and the electronic variable valve30. As a result, since the muffler20discharges the exhaust gas to only the second tail pipe29, the speed of the exhaust gas is slower in a state in which the internal pressure of the muffler is and the internal resistance of the muffler is large so that the overall exhaust noise may be reduced. Through such a principle, it is possible to implement a quieter exhaust sound than that of the conventional exhaust system in a place in which the quiet exhaust sound is needed or in a vehicle traveling mode. Subsequently, describing the variable flow of the exhaust gas with reference to the 50% opening applied to the sections B, D, G, H illustrated inFIG.10, the valve gate33of the electronic variable valve30closes a half of the internal area of the first tail pipe28so that a portion of the exhaust gas introduced into the first external connection tube25of the muffler20is discharged to the atmosphere. Therefore, the muffler20discharges the exhaust gas introduced into the inlet tube23to only the second tail pipe29in a state in which only a portion of the first tail pipe28of the two first and second tail pipes28,29is closed, theoretically reducing the area of discharging the flow rate of the first tail pipe28side by 20 to 30%. Therefore, a condition of reducing the flow rate or cross-sectional area of the exhaust gas discharged to the atmosphere in the exhaust system1-1is a same as the condition of reducing the diameter of the tail pipe through which the exhaust gas is discharged in the structure of the general exhaust system. As illustrated inFIG.11, the condition of the muffler is optimized in an idle driving area or a low RPM driving area, which has a basic flow rate of the exhaust gas a little smaller than the basic flow rate of the exhaust gas upon the 100% opening of the valve. Therefore, the muffler20may implement a Mild-sporty exhaust sound compared to the quiet exhaust sound upon 0% opening illustrated inFIG.9. Furthermore, describing the variable flow of the exhaust gas with reference to the 100% opening applied to the sections E, I, K illustrated inFIG.11, the valve gate33of the electronic variable valve30fully opens the internal area of the first tail pipe28so that the exhaust gas introduced into the first external connection tube25of the muffler20may be discharged to the atmosphere. Therefore, the muffler20discharges the exhaust gas introduced into the inlet tube23to two paths through the two first and second tail pipes28,29having the external diameters of a same sizes (e.g., Φ54) at the flow rate of 50%:50%. Therefore, the discharging of the flow rate through two paths at 50%:50% has a same condition as when there is no electronic variable valve30so that the exhaust gas is directly discharged to the first and second tail pipes28,29of a relative short path, and the speed at which the exhaust gas is discharged is fast, causing a large noise so that the tough combustion sound of the engine is discharged at it is so that the driver may feel the sporty exhaust sound. Therefore, the muffler20reduces the resistance against the flow of the exhaust gas so that a reflection pressure (load) transferred to the engine is low, contributing to increasing the output of about 2 to 5 PS in a RPM area of the engine. InFIG.9, the electronic variable valve30is matched with the sections A and C of the quiet exhaust sound-based map54-1A and the sections F and J of the sporty exhaust sound-based map54-1B according to the change in the accelerator pedal stroke from the aforementioned conditions, implementing the following operations and effects. In the section A, in a section of a N stage racing and having very low engine torque of the vehicle1, even if the accelerator pedal stroke is large, the electronic variable valve30maintains the closing (0% opening), and thus the exhaust gases coming from the left/right mufflers20-1,20-2are discharged to only the first tail pipe28of the first and second tail pipes28,29, implementing the most quiet exhaust sound. The section C is a section corresponding to “slow acceleration/constant speed driving” of the low speed, and the electronic variable valve30maintains the closing (0% opening), and thus the exhaust gases coming from the left/right mufflers20-1,20-2are discharged to only the first tail pipe28of the first and second tail pipes28,29, implementing the most quiet exhaust sound. In the section F, in a section having very low engine torque of the vehicle1, even if the accelerator pedal stroke is large, the electronic variable valve30maintains the closing (0% opening), and thus the exhaust gases coming from the left/right mufflers20-1,20-2are discharged to only the first tail pipe28of the first and second tail pipes28,29, implementing the most quiet exhaust sound. Since the section J is a slow acceleration driving section upwards to the speed of 0→50 Km, the electronic variable valve30maintains the closing (0% opening), and thus the exhaust gases coming from the left/right mufflers20-1,20-2are discharged to only the first tail pipe28of the first and second tail pipes28,29, implementing the quiet exhaust sound. Furthermore, inFIG.10, in the section B, in a section in which the engine torque is largely needed (e.g., uphill traveling) even in a section having a very low RPM, the exhaust pressure is required to be reduced to alleviate the burden of the vehicle output, and furthermore, the electronic variable valve30maintains the 50% opening due to the burden of the low-speed booming, and thus the exhaust gases coming from the left/right mufflers20-1,20-2are discharged from the first and second tail pipes28,29at the differentiated flow rates, implementing the Mild-sporty exhaust sound. Since the section D is a section before entering the high-speed RPM, the electronic variable valve30maintains the 50% opening, and thus the exhaust gases coming from the left/right mufflers20-1,20-2are discharged from the first and second tail pipes28,29at the differentiated flow rates, implementing the Mild-sporty exhaust sound and emphasizing some amount of exhaust sounds upon shifting. Since the sections G and H are sections corresponding to the “slow acceleration/constant speed driving” of the N stage racing and the low and medium speeds, the electronic variable valve30maintains the 50% opening, and thus the exhaust gases coming from the left/right mufflers20-1,20-2are discharged from the first and second tail pipes28,29at the differentiated flow rates, implementing the Mild-sporty exhaust sound. Furthermore, inFIG.11, since the section E is the medium and high speed and sudden start section, and a section in which the accelerator pedal stroke increases, the electronic variable valve30maintains the 100% opening, and thus the exhaust gases coming from the left/right mufflers20-1,20-2are discharged from the first and second tail pipes28,29at the same flow rates, implementing the sporty exhaust sound. Since the sections I and K are the medium a high speed and sudden start sections and the accelerator pedal stroke is large, the electronic variable valve30maintains the 100% opening, and thus the exhaust gases coming from the left/right mufflers20-1,20-2are discharged from the first and second tail pipes28,29at a same flow rates, implementing the sporty exhaust sound. Meanwhile,FIG.12, andFIG.13illustrate the actual exhaust sound evaluation results of the vehicle exhaust system according to the valve operation map by applying the electronic variable valve30to each of the left/right mufflers20-1,20-2to control the valve opening. As illustrated, the engine exhaust sound evaluation results prove that the engine exhaust sound level in the SMART DRIVE MODE-ECO/COMFORT states using the quiet exhaust sound-based map54-1A (FIG.12, a solid-lined line diagram) may implement a quieter exhaust sound in the low RPM area, and the engine exhaust sound level in the SMART DRIVE MODE-SPORT state using the sporty exhaust sound-based map54-1B (FIG.13, a solid-lined line diagram) may implement the differentiated and emphasized sporty exhaust sound in the low RPM area/start area and the high speed area. As described above, the method for automatically changing the engine exhaust sound in conjunction with the traveling mode implemented by the exhaust system1-1applied to the vehicle1according to the exemplary embodiment of the present invention may vary the valve opening of the electronic variable valve30provided in the first tail pipe28of the first and second tail pipes28,29of the muffler20discharging the exhaust gas coming from the engine by the mode recognition logic50connected to the engine ECU1A to the atmosphere, and control the variation of the valve opening with the engine torque and the engine RPM based on the change in the accelerator pedal stroke in any one of the SMART DRIVE MODE-ECO state, the SMART DRIVE MODE-COMFORT state, and the SMART DRIVE MODE-SPORT state, implementing the quiet engine exhaust sound and the sporty engine exhaust sound depending on various vehicle traveling states provided by the SMART DRIVE MODE and increasing the vehicle/engine outputs, and may reflect the driving style and habit according to the change in the accelerator pedal stroke, generating the differentiated exhaust sound according to the automatic change in the engine exhaust sound. Furthermore, the term “controller”, “controller” or “controller” refers to a hardware device including a memory and a processor configured to execute one or more steps interpreted as an algorithm structure. The memory stores algorithm steps, and the processor executes the algorithm steps to perform one or more processes of a method in accordance with various exemplary embodiments of the present invention. The controller according to exemplary embodiments of the present invention may be implemented through a nonvolatile memory configured to store algorithms for controlling operation of various components of a vehicle or data about software commands for executing the algorithms, and a processor configured to perform operation to be described above using the data stored in the memory. The memory and the processor may be individual chips. Alternatively, the memory and the processor may be integrated in a chip. The processor may be implemented as one or more processors. The controller or the controller may be at least one microprocessor operated by a predetermined program which includes a series of commands for carrying out the method included in the aforementioned various exemplary embodiments of the present invention. The aforementioned invention can also be embodied as computer readable codes on a computer readable recording medium. The computer readable recording medium is any data storage device that can store data which may be thereafter read by a computer system. Examples of the computer readable recording medium include hard disk drive (HDD), solid state disk (SSD), silicon disk drive (SDD), read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy discs, optical data storage devices, etc and implementation as carrier waves (e.g., transmission over the Internet). In various exemplary embodiments of the present invention, each operation described above may be performed by a controller, and the controller may be configured by a plurality of controllers, or an integrated controller. For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner”, “outer”, “up”, “down”, “upwards”, “downwards”, “front”, “rear”, “back”, “inside”, “outside”, “inwardly”, “outwardly”, “interior”, “exterior”, “internal”, “external”, “inner”, “outer”, “forwards”, and “backwards” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. It will be further understood that the term “connect” or its derivatives refer both to direct and indirect connection. The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described to explain certain principles of the present invention and their practical application, to enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the present invention be defined by the Claims appended hereto and their equivalents. | 47,193 |
11859525 | DETAILED DESCRIPTION The following description is presented to enable any person skilled in the art to make and use the invention. For the purposes of explanation, specific nomenclature is set forth to provide a plural understanding of the present invention. While this invention is susceptible of embodiment in many different forms, this description describes and the drawings show specific embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. FIG.1shows diagram view of a turbocharger manifold10deployed with an internal combustion engine12and two turbochargers14,16in an engine system20. The manifold10comprises a first exhaust conduit22, and a second exhaust conduit24, a bridge conduit26, and a valve28. The first exhaust conduit receives exhaust gas from an engine, such as in internal combustion engine12, at a first end29. In some embodiments, the first exhaust conduit connects to an exhaust manifold (not shown) or headers (not shown) of the engine12. The exhaust manifold or headers of the engine route engine exhaust gas away from one or more engine cylinders360. Opposite of the engine, the first exhaust conduit has a second end30that is for connecting to a first turbocharger14at a first turbocharger outlet43. The second end is for connecting to an exhaust intake opening or port350of the turbocharger14. The second exhaust conduit24joins to the first exhaust conduit22at a first intersection32, between the engine12and the second end30. In some embodiments the second exhaust conduit24joins to the first exhaust conduit adjacent the engine12as shown inFIG.1. The valve28controls access to or along the second exhaust conduit. In some embodiments, the valve is located at or adjacent the intersection32. Opposite of the intersection32, the second exhaust conduit has a second end34that is for connecting to a second turbocharger16via a second turbocharger outlet47. The second end is for connecting to an exhaust intake opening or port108of the turbocharger16. The third exhaust conduit has a first end36that is for connecting to an exhaust exit opening or port of the first turbocharger14. A second end38of the third exhaust conduit joins with the second exhaust conduit24for connecting to the exhaust intake opening or port108of the turbocharger16. An exhaust exit opening or port112of the second turbocharger16may be connected to other exhaust system components such as exhaust pipe(s)40, catalytic converter(s) (not shown), and/or muffler(s) (not shown). FIG.2shows the manifold10ofFIG.1using the same figure labels for the same parts. The first end29of the first exhaust conduit22comprises a first exhaust inlet39and a flange41connectable to a corresponding exit flange (not shown) of an exhaust manifold (not shown) or headers (not shown) of the engine12. The second end30comprises a second a first turbocharger outlet43and a flange44for connecting to the exhaust inlet of first turbocharger14. The second exhaust conduit24comprises a second turbocharger outlet47and a first flange46at end34for connecting to the second turbocharger16. The second exhaust conduit comprises a leg48. The bridge conduit26is connectable to the second exhaust conduit at a flange50. In some embodiments, the second exhaust conduit comprises a Y-intersection52at the terminal end of the leg48. At the end36is a bridge exhaust inlet37and a flange54for connecting to the exhaust exit opening350of the first turbocharger14. The valve28comprises a door42. The door is shown in a closed position at42and in an open position at42a. The door42is movable between the open and closed positions (directions H and I ofFIG.2) via an arm mechanism55. The arm mechanism55is the same as arm mechanism117explained below. In some embodiments, an actuator51comprises a moveable rod53that is connected to the arm mechanism55to move the arm mechanism and the door between the open and closed positions. The actuator is mounted to a portion of the exterior of the conduit24as shown inFIG.2. In some embodiments, the terminal end of the rod53is pivotally connected to the arm mechanism with a hinge or pivot connection to allow the rod to move with the arm mechanism in an arcing motion about a pivot location31of the arm mechanism55. In some embodiments, the actuator can be pivotally mounted to the conduit24at a rear pivot location35to allow the actuator and the rod53to move with the arm mechanism55between the open and closed positions. In some embodiments, the actuator51is the same as actuators320or322, as described below. In some embodiments, instead of actuator51, the actuator is a motor45, that rotates the arm mechanism55at or about the pivot location between the open position and the closed position. In some embodiments, the motor45is the same as motors325or327explained below. In some embodiments, the second exhaust conduit comprises the third exhaust conduit and the flange50is not used. The third exhaust conduit may be unitary with the second exhaust conduit. FIG.3shows a second embodiment turbocharger manifold60deployed with an internal combustion engine12and two turbochargers14,16in an engine system62. The manifold60comprises a first exhaust conduit64, a second exhaust conduit68, a third exhaust conduit66, a fourth exhaust conduit70, a fifth exhaust conduit or bridge conduit72, a first valve74, and a second valve76. The valves74,76,28are the same, but oriented differently as shown and described herein. The first exhaust conduit64receives exhaust gas from an engine, such as in internal combustion engine12, at a first exhaust inlet75at a first end79. In some embodiments the first exhaust conduit64connects to an exhaust manifold (not shown) or headers (not shown) of the engine12. The first exhaust conduit has a second end80that is for connecting to the first turbocharger14. The second end80is for connecting to an exhaust intake opening or port350of the turbocharger14. The second end80comprises a first turbocharger outlet section83. The first turbocharger outlet section83comprises a first turbocharger outlet85. The third exhaust conduit66receives exhaust gas from an engine, such as in internal combustion engine12, at an exhaust inlet77at a first end81. In some embodiments the third exhaust conduit66connects to an exhaust manifold (not shown) or headers (not shown) of the engine12. The third exhaust conduit has a second end82that is for connecting to the first turbocharger14at the first turbocharger outlet85. The second end82is for connecting to an exhaust intake opening or port350of the turbocharger14via the first turbocharger outlet85. The second end80of the first exhaust conduit64and the second end82of the third exhaust conduit66join at a first intersection84and connect therefrom to the turbocharger14at the first turbocharger outlet85. The second exhaust conduit68joins to the first exhaust conduit64at a second intersection86, between the engine12and the second end80. The valve74controls exhaust gas access to or along the second exhaust conduit68. In some embodiments, the valve74is located at or adjacent the second intersection86. Opposite of the intersection86, the second exhaust conduit68has a second end88that is for connecting to a second turbocharger16at a second turbocharger outlet95. The second end is for connecting to an exhaust intake opening or port108of the turbocharger16at the second turbocharger outlet95. The fourth exhaust conduit70joins to the third exhaust conduit66at a third intersection90, between the engine12and the second end92. The valve76controls access to or along the fourth exhaust conduit70. In some embodiments, the valve76is located at or adjacent the intersection90. Opposite of the intersection90, the fourth exhaust conduit has a second end92that is for connecting to a second turbocharger16at the second turbocharger outlet95. The second end is for connecting to an exhaust intake opening or port108of the turbocharger16at the second turbocharger outlet95. The second end88of the second exhaust conduit68and the second end92of the fourth exhaust conduit70join at a fourth intersection94for a joint conduit connection at the second turbocharger outlet95to an exhaust intake opening or port108of the turbocharger16. A bridge port conduit101extends rearward from the fourth intersection94at a first end99. The first end99joins with the second and fourth exhaust conduits68,70at the fourth intersection94. The conduit101has a bend103, between the first end99and a port outlet107of the conduit101. In some embodiments the bend103is a ninety-degree bend. The terminal end of the port conduit101comprises a flange105and the port inlet107. A second end98of the fifth exhaust conduit72comprises a flange109and is releasably connected to the flange105of the bridge port conduit101to direct exhaust in the fifth exhaust conduit into the intersection94. The fifth exhaust conduit72can be connected to the bridge port conduit101with a clamp, such as a v-band. A first end96of the fifth exhaust conduit72is connectable to the exhaust exit port354of the first turbocharger. An exhaust exit opening or port112of the second turbocharger16can be connected to other exhaust system components such as exhaust pipe(s)100, catalytic converter(s) (not shown), and/or muffler(s) (not shown). FIGS.4through11B, show an embodiment of the manifold60ofFIG.3using the same figure labels for the same parts.FIGS.4to6,10,11Ado not show the fifth exhaust conduit72, which is shown inFIGS.7through9. In some embodiments the first and third exhaust conduits64,66form a w-shape as shown inFIG.4. In some embodiments the second and fourth exhaust conduits68,70form a u-shape as shown inFIG.4. In some embodiments, a first turbocharger outlet section83extends from the intersection84for connecting with the exhaust intake port350of the first turbocharger. In some embodiments, the first ends79and81of the first and third exhaust conduits comprise flanges (not shown) for joining the first and second exhaust conduits with an exhaust manifold(s) or header(s) of the engine. In some embodiments, a flange97is mounted to or adjacent the fourth intersection for joining the third, fourth, and fifth exhaust conduits to the exhaust intake port108of the second turbocharger16. As shown inFIG.5, the intersection94and/or a portion extending from the intersection, and the opening102of the outlet95, is angled forward from the angle of the first turbocharger outlet section83. Therefore, the second turbocharger16when mounted at the flange97is forward of the outlet section83and the first and third exhaust conduits64,66, as further shown inFIGS.11A and11B. FIG.8shows an example first turbocharger14mounted to the outlet section83of the turbo charger manifold with a clamp106at an exhaust inlet port350of the turbocharger. In some embodiment the clamp is a v-band clamp. The first end96of the fifth exhaust conduit72is connected to an exhaust outlet352of the turbocharger14. Therefore, the exhaust gas exiting the first turbocharger is directed to the exhaust inlet of the second turbocharger16via the intersection94and the outlet95. FIGS.11A and11Bshows an example second turbocharger16connected at the second turbocharger outlet95. An extension109is added to raise the second turbocharger outlet95above the intersection94. The extension109can be integrally formed with the intersection94. The exhaust intake port108of the second turbocharger16is connected to the second turbocharger outlet95with a clamp111, such as a v-band. In some applications, a further exhaust pipe100is connected to the exhaust outlet fitting110of the exhaust exit112. In some embodiments, an extension109can be used to position the second turbocharger in the desired position. FIG.11Bshows the first turbocharger14and the second turbocharger16mounted to the manifold60, with the bridge conduit72connected to the first turbocharger.FIG.11Bshows an exemplary application where the first turbocharger14is smaller than the second turbocharger16. FIGS.12to15show a section of the manifold60comprising valve74and a portion of exhaust conduits64,68. Valve76at the intersection of exhaust conduits66,70is the same as valve74at the intersection of exhaust conduits64,68, except it valve76rotated 180 degrees about a mid-plane114(FIG.7) bisecting the manifold60. Therefore, only valve74will be described in detail. The valve comprises a door116and an arm mechanism117. The arm mechanism comprising a first and second door arms118,120, and a first and second mount arms122,124, and a connecting bar125. Distal ends126,128of the respective mount arms122,124are pivotally mounted to respective side mounting plates130,132. The side mounting plates130,132are attached at and adjacent the intersection of exhaust conduits64and68. The plates create a semi enclosed space134between the intersecting exhaust conduits as shown inFIGS.12,14, and15at a corner of the intersection. In some embodiments, the mounting plates are joined to the respective conduits64,68at or adjacent first edges136,138of the respective plate. Between the first edges of each plate is a second curved edge140,142. The curved edges140,142extend from exhaust conduit64to exhaust conduit68. The mount arm122is located on the outside side of plate130and mount arm124is located on the outside side of the plate132. The door arms118,120are located between the plates130,132and between arms122,124. The plates130,132comprise an aperture (not shown) where pins144,146are mounted. The pivot pins extend through apertures (not shown) in the respective arms122,124. The pins have heads or outside washers148,150that are larger than the apertures in the respective arms122,124. The heads or washers are formed with or fixed to the pins to secure the arms122,124to the respective pins144,146and therefore pivotally to the respective plates130,132. In some embodiments, the plates130,132do not have apertures at the pins and the pins are fixed to the outside surface of the respective plates. In some embodiments, each of the mount arms122,124comprise a first arm portion152,154and a second arm portion156,158. The first arm portions152,154each comprise a mouth160,162. The second arm portion156,158is received into the respective mouth160,162. In some embodiments the mouth160,162covers the second arm portion on at least a portion of two sides. The second arm portion is shaped and sized to be received into the respective mouth. In some embodiments, fasteners, such as bolts or bolt and nut combinations or screws,164,166,168,170join the second arm portion to the respective mouth. In some embodiments, the second arm portions156,158, the connecting bar125, and the door arms118,120are formed of a unitary piece of material. The connection bar125extends transverse to the second arm portions156,158, the mount arms122,124, and the door arms118,120. In some embodiments, the connection bar125is perpendicular to the second arm portions156,158, the mount arms122,124, and the door arms118,120. The door arms118,120join to the connection bar125inward of and between the mount arms122,124. In some embodiments, the connection bar125comprises offset portion172between opposite end portions174,176. The offset portion172is offset from the end portions174,176. The offset portion173provides a back recess178that can accommodate the conduit64and allow a greater range of motion of the connecting bar, the door, and the valve. In some embodiments, the door arms118,120each comprise a first portion180,182and a second curved portion184,186. The first portions are non-curved and joined to the respective curved portions. A door mount188is connected to the door arms118,120opposite the connecting bar125. The door mount188is fixed to the door116. In some embodiments the door mount188is fixed to the door116with a fastener190, such as a bolt or screw. The door mount comprises a concave curve and profile between the door arms118,120. The door arms can be fixed to the door mount with fasteners192,194, such as pins. The door arms118,120extend through or are moveable through, depending on the position of the valve, an arm aperture196in the exhaust conduit68. FIGS.16and17show a cutout view of the intersection of the exhaust conduits64and68showing an interior of the conduit64and conduit68(FIG.16). An interior bottom portion200of exhaust conduit64comprises a bypass aperture198providing access to exhaust conduit68. InFIG.17, the door116of valve74is in a closed position, covering the bypass aperture198and closing and blocking exhaust gas access to the exhaust conduit68from exhaust conduit64. InFIG.16, the door116of valve74is an open position, where the door is against or adjacent an interior sidewall202of the conduit68, and the aperture198is open allowing exhaust gas access from the exhaust conduit64to the exhaust conduit68. The valve, arm mechanism, and door are shown in an open position inFIGS.12and14and in a closed position inFIGS.13and15. InFIG.14, the door arms extend through arm aperture196and into conduit68. All or a substantial portion of the curved portion184,186are within the conduit68when the valve is in the closed position. The curved portions184,186cause the door to move to cover the aperture198when the valve is moved to the closed position. FIGS.18to20show a second embodiment valve204that can be used in place of valve74,76, and/or28. The second embodiment valve204comprises the same door116as valve74. The valve204comprises an arm mechanism206that is similar to the arm mechanism117, except as shown and described. The arm mechanism206comprises a first and second door arms218,220, and a first and second mount arms222,224, and a connecting bar225. Distal ends226,228of the respective mount arms222,224are pivotally mounted to respective side mounting plates130,132at apertures227,229with pins144,146as described with valve74. The connection bar225comprises an offset portion225between opposite end portions228,230. The end portions228,230each comprise recesses232,234. The end recess232,234receives terminal ends236,238of the mount arms222,224. The mount arms may be fixed to the connection bar225at the terminal ends236,238with fasteners, such as bolts or screws240. Ends246,248of the door arms opposite the door mount250are mounted to the connection bar225within the recess244by fasteners (not shown) at apertures252,254. The door mount250comprises recesses256,258for receiving ends260,262of the door arms, which can be fixed thereto with fasteners at apertures265. The door mount is mounted to the back264of the door116at apertures266,268with fasteners. The door116has a concave profile from a first side272to a second side273. The concave curve and profile conforms to the curve and profile of the bottom200of the conduit64. FIGS.19,20and21show the interior side274of the door116. In some embodiments, the interior side274comprises a perimeter recess276. The perimeter recess276is recessed from the main surface275of the interior side274. The first wall280between the recess276and the main surface comprises a top edge282and a bottom edge277. At the outer edge278of the recess276is an outer sidewall284, which may be angled. In some applications, the perimeter recess contacts the exterior side of conduit64within conduit68about the aperture198, and the main surface275is within the aperture198, when closed. FIGS.22and23show a cover290. The cover is for coving around the arm aperture196in the conduit68. The cover has arm apertures292,294for the door arms118,120, or218,220respectively to extend through. Therefore, the connecting bar125,225and the mount arms122,124are outside of the cover, while a portion of the door arms118,120,218,220are inside296of the cover when in use. In some embodiment, the290cover has a rectangular shape. The cover has a front wall298and sidewalls300,302,304,306. The longer first and second sidewalls300,302have a concave cut-outs308,310, and are concave between the third and fourth sidewalls304,306. Therefore, the first and second sidewalls300,302have a concave curved back edge312,314opposite the front wall298. The back edges316,318of the third and fourth sidewalls300,302opposite the front wall298are beveled toward the inside296as shown inFIG.22. The concave back edges312,314allow the cover to conform to the curvature of the outside wall of the conduit68in the general directions A and B ofFIG.15adjacent the arm aperture196along the aperture's196longer length. The beveled back edges316,318allow the cover to conform to the curvature of the outside wall of the conduit68adjacent the arm aperture196along the aperture's196shorter width. In some embodiments, the arm apertures292,294are sized to closely fit around the door arms, either by surface-to-surface contact about the door arm at the points of intersection or by being closely adjacent thereto. The close fit can seal against gas escape from the cover and the exhaust conduit68if gas passes through the arm aperture196into the inside of the cover. Further, the cover can be mechanically held against conduit68about the arm aperture196with a fastener, such as a clamp, or adhesive. Therefore, the edges312,314,316,318can contact and seal to the outside surface of the conduit68about the arm aperture196. As shown inFIG.8, in some embodiments, the manifold60comprises or has attached actuators320,322for moving the arm mechanism117of valves74and76between, to, and from the closed position and the open position. In some embodiments, the actuators are linear actuators. The actuators comprise a moveable rod324,326. The terminal end of the rod324,326are connected328,330attached to the connecting bar125,225of valves74,76. In some embodiments, the connection328,330is a hinged or pivot connection which allows the terminal end of the rod324,326to pivot relative to the connecting bar125,225as the valve moves between closed and open positions in the directions F and E for valve74and H and G for valve76. The valves74,76are shown in or close to the closed position inFIG.8. Therefore, when the rods of the actuators are in a retracted position, the valves are in a closed position. When the rods of the actuators are extended to an extended position, the valves are in the open position, with the door116of the valves76,74adjacent or against the inside wall of conduits68,70, and the respective apertures between conduit64and68and conduits66and70open. In some embodiments, the rods can move in an arc motion to follow the arc motion of the connecting bar125,225moving along the path defined by its connection via the mount arms122,124,222,224to the pins144,146and the plates130,132. In some embodiments, the rods comprise a curved portion332,334and a straight portion as shown inFIG.8. The straight portion is adjacent the actuator housing336,338. The curved portions332,334assist or allow in following the curved path of the connecting bar125,225from and to the open and closed positions. In some embodiments, the actuators are pressure or vacuum operated. In some embodiments, pressure operated actuators comprise a chamber comprising a diaphragm and a spring biasing the diaphragm to a first position corresponding to a retracted position of the rod324,326. The diaphragm operatively moves the rod from the retracted position to an extended position when a predefined open pressure is applied to the diaphragm to overcome the spring bias of the spring. When pressure drops below the predefined open pressure, the spring overcomes the pressure to move the diaphragm back toward and to the first position and therefore retracts the rod to the retracted position. In some embodiments, pressure supplied to the actuators is pressure from the manifold10,60ahead of the first turbocharger. This pressure may be known as exhaust back pressure. Therefore, a pressure control conduit (not shown) can extend from conduit64,64or24to the actuator. The actuation of the actuators and therefore the positions of the valves can be controlled by based on the pressure in the manifold10,60upstream of the first turbocharger. When the actuator is vacuum operated, vacuum is applied and/or released from one side of the diaphragm causing the diaphragm to move, which causes the operatively connected rod to move. In some embodiments, the actuators are electro-mechanical linear actuators. In some embodiments, the electro-mechanical linear actuators comprise a motor and a gear mechanism, such as a leader screw and a nut. The leader screw comprises threads. A nut is operably fixed to the movable rod and engaged to the threads of the leader screw. The rotation of the lead screw by the motor is a first rotation direction causes the nut to move in a first linear direction along the screw, thus moving the rod with it in the first linear direction. The rotation of the screw by the motor in a second rotation direction opposite the first rotation direction causes the nut to move in a second linear direction opposite the first linear direction along the screw, thus moving the rod with the nut in the second linear direction opposite the first linear direction. Therefore, powering the motor to rotate in one direction causes the rod to extend and powering the motor to rotate in the opposite direction causes the rod to retract. In some embodiments, the actuator that controls each valve74,76is a motor325,327(shown diagrammatically inFIG.9), such as a servomotor. Each motor is connected to the respective pins144,146or to the respective arms122,124,222,224at or about the pins to rotate the arms from and to the open and closed positions for each respective valve74,76. FIG.24shows an exemplary block diagram of turbocharger14, which, in some embodiments, is the same as turbocharger16. The turbocharger14comprises a turbine340and a compressor342. The turbine340is connected to the compressor such as by a shaft344. The turbine drives the compressor. The turbine is rotated by the force of exhaust gas from the engine12passing through the turbine housing346from an exhaust inlet350to an exhaust outlet352. The exhaust gas turns the turbine which is connected to the shaft344which turns the compressor342. The compressor342receives ambient air from an inlet354and forces the air out the forced air outlet356of the compressor housing348. The compressor compresses the air forced out of the air outlet356at a pressure higher than atmospheric pressure. In some embodiments, the turbine comprises turbine fan blades (not shown) for capturing the momentum of the exhaust air flowing through the turbine housing and causing the turbine to rotate. The turbine housing directs the exhaust gas to follow through and spin the turbine. In some embodiments, the compressor is a centrifugal compressor comprising an impeller and a diffuser. The impeller raises the energy of the intake air. The diffuser is downstream of the impeller and coverts the kinetic energy of the air/gas into pressure by slowing the gas velocity. A collector is downstream of the diffuser to gather the flow of air/gas from the diffuser and deliver this flow to a downstream conduit, which may be joined to the outlet356. The outlet356of the compressor is connected to the intake manifold at390of the engine12. FIG.25shows a block diagram of a portion360of the engine12including a cylinder362, and a portion of a crankshaft370. The engine may have any number of cylinders, such as 2, 3, 4, 5, 6, 8, 10, or 12 cylinders. The cylinder362comprises a piston364connected to a connecting rod366. The connecting rod366is rotatably connected at a terminal end368to a crankpin374of a crankshaft370(partially shown inFIG.25). The crankshaft370is journaled to rotate in the engine block of the engine at block journal location372on the crankshaft where the engine main bearings are located between the crankshaft and the engine block. The cylinder has four cycles: an intake, compression, combustion, and exhaust cycles. During the intake cycle, the intake valve or valves (not shown) are opened to allow air and fuel to enter the cylinder362through an intake opening376and the piston is drawn down in direction D by the crankshaft to draw air and fuel into the cylinder. The forced air from the turbocharger increases the density of the intake gas/air entering cylinder during the intake cycle. The increase in density of the intake gas/air allows more power per engine cycle. FIG.29is a block diagram showing that the compressed/forced air of the compressor of the turbochargers14,16is routed to the engine, usually through an engine intake manifold at390. The output of the compressors of the turbochargers14,16are routed to intake opening of the cylinders of the engine. At the end of the intake cycle the intake valve or valves are closed and the crankshaft drives the piston upward in the direction C to compress the air and fuel within the cylinder above the piston. When the piston is at or about the top of its up and down travel allowed by the rotation of the crankshaft, a spark is provided at the spark plug380, which extends into the top of the cylinder. The spark ignites the air fuel mixture compressed in the cylinder above the piston, causing fuel to burn and release energy driving the piston downward in the direction D, and driving the crankshaft to rotate. When the piston reaches the bottom of its up and down travel, one or more exhaust valves (not shown) will open to allow exhaust gas to exit the cylinder through an exhaust opening378. The exhaust gas will be received in an engine exhaust manifold or headers. The engine exhaust manifold or headers are connected to the turbocharger manifold at exhaust inlets75,77or39. Therefore, the turbocharger manifold receives the exhaust gas from the engine. In some applications, an engine will have two exhaust manifolds, a first exhaust manifold for receiving exhaust from a first set of cylinders of the engine and the second exhaust manifold for receiving exhaust from a second set of cylinders of the engine. Therefore, the two inlets75and77allow the turbo manifold60to receive exhaust exiting from two exhaust manifolds. In some applications, one engine exhaust manifold may have two exit openings. Therefore, each of the openings can be connected to one of the inlets75,77so that the turbocharger manifold60can collect all of the exhaust gas from the engine. In some embodiments, a controller382controls the operation of the actuators320,322or325,327, or51,45to control the position of the valves74,76, or28. The controller382is connected by wire or wireless connection to a pressure sensor and/or a turbo speed sensor as shown inFIG.26. The controller is connected by wire or wireless connection to the actuators320,322or325,327in the case of manifold60or actuator51or45in the case of manifold10. The controller is configured to send control signals and/or power to direct the movement of the actuators. In some embodiments, the control signals and/or power are sent based on the data received from the one or both of the sensors384,386. In operation, the controller is configured to and will instruct and/or power the actuators to move or position the valves28,74,76to the closed position at lower engine operating speeds up to a predefined open threshold. In the case where the actuators320,322,51are pressure or vacuum operated, the actuators are configured to maintain the valves in a closed position at pressure or vacuum corresponding to lower engine operating speeds up to the predefined open threshold. Therefore, all of the exhaust gas will be directed via conduits64and66, in the case of manifold60or conduit22in the case of manifold10, to the first turbocharger14. When the predefined open threshold is reached, the valves28,74,76are opened, to allow some of the exhaust gas to travel in conduits68,70in the case of manifold60and conduit24in the case of manifold10, to the second turbocharger16. In the case where the actuators320,322,51are pressure or vacuum operated, the actuators are configured to move the valves28,74,76to the open position when the pressure or vacuum corresponding to the predefined open threshold is reached. In the case of the use of a controller283to control the actuators, the controller is configured to and will instruct and/or power the actuators to move or position the valves2874,76to the open position when the predefined open threshold is reached or exceeded. The turbocharger manifolds10,60direct the exhaust gas exiting the first turbocharger14to the second turbocharger16via conduits26and72to the second turbocharger16even when the valves2874,76are closed. In some embodiments, the predefined open threshold is set at the peak efficiency threshold of the first turbocharger14. The peak efficiency can be correlated to a speed of rotation of the turbocharger and/or a manifold pressure leading up to the first turbocharger in the turbocharger manifold60. In some embodiments, the turbocharger14comprises a speed sensor384that measures and reports the rotational speed of the compressor and/or the turbine of the turbocharger14to the controller382. In some embodiments, the turbocharger16comprises a speed sensor383that measures and reports the rotational speed of the compressor and/or the turbine of the turbocharger16to the controller382. In some embodiments, conduits22,64, and/or66comprise a pressure sensor386that measures and reports the pressure within the respective conduit. Therefore, the pressure sensor386can measure the pressure in the turbocharger manifold upstream of the first turbocharger14. The pressure sensor can be mounted to extend into the conduit to measure the pressure. The connection between the sensor and the conduit will be air-tight. Therefore, when a predefined open rotation speed of the first turbocharger14is reached or exceeded as reported by the speed sensor384and/or a predefined open manifold pressure is reached or exceeded in the manifold exhaust conduit(s) upstream of the first turbocharger as reported by sensor(s)386, the valves2874,76will open. Before and below such predefined open speed and/or such predefined open manifold pressure is reached valves are and remain closed. In this manner all or substantially all of the exhaust gas from the engine is directed into the first turbo until the predefined open threshold(s) are reached. After a one or more of the open threshold(s) are reached the valves28,74,76are opened to divert some of the exhaust gas from reaching the first turbo charger and directing it through conduits24,68,70to the second turbocharger16. In some applications, the actuators open or the controller is configured to direct the actuators to open the valves when the first turbo charger reaches peak efficiency so that diverting exhaust gas to the second turbo charger will provide better performance gains from the engine than continuing to deliver all exhaust gas to the first turbocharger. While peak efficiency of the first turbocharger is one threshold at which the controller or the actuators could be configured to open the valve, other user selected or programed thresholds may be used depending on the selected components, such as type and size of the turbos, engine size, and/or other components, and the performance goals of the users. Therefore, the condition(s) upon which the valves are caused to be open or can be selected by the user to achieve the desired performance. In some embodiments, the controller382is an engine control unit (ECU) that controls the operation of the engine12, and components of thereof, as well as the valves28,74,76. The ECU may also receive data from one or more other sensors for controlling engine operation. In some embodiments, the controller382is in communication with and/or directed by the ECU. In some embodiments, the references to conduit herein includes pipe as a conduit. The conduit(s) of the turbocharger manifolds disclosed herein have one or more enclosing walls that are gas impermeable so as to contain the exhaust gas within the conduit and allow it to travel in the open space within the conduit bounded by the enclosing wall or walls. In some embodiments, a turbocharger wastegate is added at location113(FIG.9). In some embodiments, the controller382comprises processing circuitry. The processing circuitry may comprise one or more of microprocessor(s), microcontroller(s), a hardware circuit(s), application-specific integrated circuit(s) (ASIC), digital signal processor(s) (DSP), field-programmable gate array(s) (FPGA), discrete logic circuit(s), or combinations thereof for performing the operations of the controller382or the ECU. From the foregoing, it will be observed that numerous variations and modifications may be affected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. For example, one or more component embodiments may be combined, modified, removed, or supplemented to form further embodiments within the scope of the invention. Further, steps could be added or removed from the processes described. Therefore, other embodiments and implementations are within the scope of the invention. | 37,407 |
11859526 | DISCLOSURE OF THE INVENTION Surprisingly, it was found that the problem underlying the invention is solved by an exhaust gas purification system according to the claims. Further embodiments of the invention are outlined throughout the description. Subject of the invention is an exhaust gas purification system for a gasoline engine, comprising in consecutive order the following devices:a first three-way-catalyst (TWC1), a gasoline particulate filter (GPF) and a second three-way-catalyst (TWC2), wherein the platinum-group metal concentration (PGM) of the GPF is at least 40% greater than the PGM of the TWC2, wherein the PGM is determined in g/ft3 of the volume of the device. The invention relates to an exhaust gas purification system for a gasoline engine. A gasoline engine is a combustion engine, which uses petrol (gasoline) as fuel. A gasoline engine is different from a diesel engine, which does not use spark ignition. Generally, exhaust gas emitted from gasoline engines has a different composition than exhaust gas from diesel engines and requires different exhaust gas purification systems. Preferably, the engine uses gasoline direct injection (GDI), also known as petrol direct injection, because these engines are known for their improved fuel efficiency. Typically, the exhaust gas from such an engine comprises a relatively high number of relatively small soot particles. Especially for such an engine, it can be advantageous that the system is capable of efficient removal of soot particles. The purification system comprises the three devices as outlined above. Typically, the devices are different units, which can be provided in separate housings. The devices can be connected by connection means, such as tubes and/or plugs. The three devices are arranged in consecutive order, such that the TWC1 is located upstream from the GPF, which is located upstream from the TWC2. The TWC1 is positioned downstream from the gasoline engine. As used herein, the terms “upstream” and “downstream” refer to the directions of the flow of the engine exhaust gas stream from the engine towards the exhaust pipe, with the engine in an upstream location and the exhaust pipe downstream. The exhaust gas purification system comprises at least the three purification devices TWC1, GPF and TWC2. In a preferred embodiment, the system does not comprise other purification devices, especially not additional catalytic devices. More preferably, the system does not comprise another TWC, another GPF and/or another pollutant removal device, such as a separate NOxremoval device or the like. According to the invention, it was found that efficient exhaust gas purification is possible only with the three devices in the order described herein. In another embodiment, the system comprises additional devices which participate in pollutant removal. In one embodiment, at least one additional catalyst device may be present. In another embodiment, at least one additional non-catalytic device may be present. A TWC comprises a three way catalyst coating which is coated on a flow-through substrate. The term “three-way” refers to the function of three-way conversion, where hydrocarbons, carbon monoxide, and nitrogen oxides are substantially simultaneously converted. Three-way-catalysts (TWC) are known and widely used in the art. A gasoline engine typically operates under near stoichiometric reaction conditions that oscillate or are perturbated slightly between fuel-rich and fuel-lean air to fuel ratios (A/F ratios) (λ=1+/−˜0.01), at perturbation frequencies of 0.5 Hz to 2 Hz. This mode of operation is also referred to as “perturbated stoichiometric” reaction conditions. TWC catalysts include oxygen storage materials (OSM) such as ceria that have multi-valent states which allows oxygen to be held and released under varying air to fuel ratios. Under rich conditions, when NOxis being reduced, the oxygen storage capacity (OSC) provides a small amount of oxygen to consume unreacted CO and HC, Likewise, under lean conditions when CO and HO are being oxidized, the OSM reacts with excess oxygen and/or NOx. As a result, even in the presence of an atmosphere that oscillates between fuel-rich and fuel-lean air to fuel ratios, there is conversion of HC, CO, and NOxall at the same (or at essentially all the same) time. Typically, a TWC catalyst comprises one or more platinum group metals such as palladium and/or rhodium and optionally platinum; an oxygen storage component; and optionally promoters and/or stabilizers. Under rich conditions, TWC catalysts may generate ammonia. The term “platinum group metal” refers to the six platinum-group metals ruthenium, rhodium, palladium, osmium, iridium, and platinum. A “gasoline particulate filter” (GPF) is a device for removing particulate matter, especially soot, from exhaust gas. The GPF is a wall-flow filter. In such a device, the exhaust gas passes the filter walls inside the device, whereas the particles are not capable of passing the filter walls and accumulate inside the device. Typically, the filters comprise multiple parallel gas-flow channels. A plurality of first channels is open at the upstream side from which the exhaust gas streams into the channels, and closed at the opposite end in flow direction. The exhaust gas enters the first channels, passes the filter walls and enters adjacent second channels, whereas the particles remain trapped in the first channels. The second channels are closed at the upstream end and open at the opposite end downstream in flow direction, such that the exhaust gas exits the GPF. Typically, the GPF comprises a catalytically active coating, typically a TWC coating. Thereby, the overall catalytic efficiency of the overall system can be enhanced and the performance can be increased. Typically, inner surfaces of the GPF, preferably all inner surfaces, are coated with a catalyst coating. Thus, inner walls of the filter channels or at least portions thereof comprise a catalyst coating, such that the exhaust gas which passes the filter walls also flows through the porous catalyst coating. Typically, the catalytic coating is located inside the porous filter walls, or onto the filter walls, or both, inside and onto the filter walls. Thereby, the GPF can filter off particles, and at the same time removes gaseous pollutants by catalytic chemical reaction. The catalyst may also support removal of particles, especially during regeneration. A “wash coat” (WC) is a thin, adherent coating of a catalytic or other material applied to a carrier substrate. The carrier substrate can be a honeycomb flow through monolith substrate or a filter substrate, which is sufficiently porous to permit the passage of the gas stream being treated. A “wash coat layer” is defined as a coating that comprises support particles. A catalyzed wash coat comprises additional catalytic components. The wash coats of the TWC1 and TWC2 of the system are catalytic washcoats. Further, it is preferred that the GPF comprises a catalytic washcoat. According to this application, the wash coat load is determined in g/l, wherein the weight in gram corresponds to all solids in the wash coat, whereas the volume is the total volume of the device, and not only the void volume of the device in the channels. A “carrier” is a support, typically a monolithic substrate, examples of which include, but are not limited to, honeycomb flow-through substrates for the TWC and wall-flow filter substrates for the GPF. A “monolithic substrate” is a unitary structure that is homogeneous and continuous and has hot been formed by affixing separate substrate pieces together. Typically, the carrier is coated with a wash coat comprising the catalyst. An “OSM” refers to an oxygen storage material, which is an entity that has multivalent oxidation states and can actively react with oxidants such as oxygen or nitric oxide (NO2) under oxidative conditions, or reacts with reductants such as carbon monoxide (CO) or hydrogen under reduction conditions. Examples of suitable oxygen storage materials include ceria or praseodymia. Delivery of an OSM to the wash coat layer can be achieved by the use of, for example, mixed oxides. For example, ceria can be delivered as an oxide of cerium and/or zirconium and mixtures thereof, and/or a mixed oxide of cerium, zirconium, and further dopants like rare earth elements, like Nd, Pr or Y. As used herein, the “volume” of a device, such as a TWC or GPF, is the total volume of the device defined by its outer dimensions. Thus, the volume is not only the void volume within the channels or within the porous structure of the device. Preferably, the OSC is determined in fresh condition. The presence or absence of oxygen storage capacity (OSC) can be determined by a jump test. Thereby, the OSC in mg/L of a catalyst or system that is located between two λ-sensors is calculated by the time offset of the two sensor signals that is occurring after air-to-fuel ratio jumps (e.g. between λ0.95-1.05; see for example “Autoabgaskatalysatoren, Grundlagen—Herstellung—Entwicklung—Recycling—Ŏkologie”, Christian Hageliiken, 2nded. 2005, page 62). The catalyst is in fresh condition when it is put into use after manufacture. Typically, the catalytic performance changes during operation and its performance may decrease. This phenomenon is known as aging, Thus, it is preferred that the general catalyst performance is determined in aged condition, as it is required by legislation. According to the invention, the system comprises a TWC1, a GPF and a TWC2 in consecutive order. Such an arrangement of these three devices confers various advantages to the inventive system. It is an advantage of the system that the GPF can be positioned relatively close to the engine. Generally, GPFs require a relatively high temperature for optimal performance and efficient regeneration. When the engine is started, the GPF is heated by the exhaust gas stream. When the GPF is located close to the engine, it is heated faster and achieves the high, optimal operation temperature earlier. The time window in which the filter is not operated efficiently is relatively small. In conventional systems, in which the GPF is a terminal device and/or located further away from the engine, more time is required for achieving the operation temperature for efficient three-way catalyst activity and soot oxidation. Moreover, a GPF must be regenerated actively at defined time intervals if it is located too far from the engine and therefore does not reach the temperature that is required for soot burning. During regeneration, accumulated soot is burned at high temperature. If the required temperature cannot be reached, the soot may not be burned completely and undesired side products, such as CO and hydrocarbons, can be formed in the regeneration process. Therefore, it is advantageous for efficient regeneration that the GPF is located relatively close to the engine. It is another advantage of the system that the partially purified exhaust gas, which is released from the GPF, can be subjected to further purification by the downstream second TWC (TWC2). In known systems, the GPF is often the terminal purification device for final removal of particles from pre-purified exhaust gas. When the GPF is regenerated, the soot is oxidized and impurities, such as carbon monoxide (CO) or hydrocarbons (CH), can be formed. With a conventional system comprising a terminal GPF, pollutants formed during regeneration are released into the environment. According to the invention, the pre-purified exhaust gas from the GPF is subjected to downstream purification in the TWC2. Thereby, residual impurities which pass the GPF or which are formed in the GPF can be removed or at least significantly reduced. The terminal TWC2 can ensure a final catalytic purification, which can function as a finishing step in the overall purification process. It is a further advantage of the system that the TWC2 is located at a position distant from the engine. It is a known problem in the technical field that catalytic devices, such as TWCs, undergo aging during use. Aging means that the activity and performance of the catalyst changes over lifetime, and usually tends to decrease. Generally, aging occurs more rapidly at high temperature. In the inventive system, the TWC2 is positioned relatively far from the engine, which has the consequence that less heat is transferred to the TWC2 than to the upstream devices during use. Therefore, the aging process of the TWC2 is comparably slow and the catalyst can maintain its efficiency and performance for a prolonged time. This can be advantageous for long-time use, especially when emissions are monitored under RDE conditions. On the other hand, since the TWC2 is only the final catalyst for removing residual pollutants from the pre-purified exhaust gas, it can be acceptable that its performance may not be optimal at certain time intervals due to its position relatively far from the engine. The terminal downstream TWC2 can still efficiently clean up the relatively small amounts of residual pollutants, even at times when its temperature should not be as high as required for optimal function. Overall, the system with the special arrangement of the TWC1, GPF and TWC2 allows highly efficient removal of gaseous and particulate pollutants from gasoline engine exhaust gas during standard use and for a prolonged time. According to the invention, the platinum-group metal concentration (PGM) of the GPF is at least 40% greater than the PGM of the TWC2. According to the present application, the PGM is determined in g/ft3 of the volume of the device. It can be advantageous that an efficient overall purification can be achieved with the inventive system, although the PGM, and thus concomitant catalytic efficiency based on platinum group metals, of the second TWC (TWC2) can be relatively low. In this regard, the terminal TWC2 can efficiently remove the residual pollutants from the pre-purified exhaust gas from the GPF, although the amount of precious metal in the TWC2 is relatively low. Overall, an efficient purification of the exhaust gas can be achieved with a relatively moderate total amount of precious metal in the system. This is advantageous for practical applications, because the precious metals are the main cause that catalyst systems are very expensive. Generally, it is preferred that the GPF comprises a catalyst coating, preferably a TWC coating. This can be advantageous, because the GPF can then support the removal of gaseous pollutants by the system. Thereby, the limited space in the system can be used more efficiently compared to a GPF without a catalyst coating. Further, the catalyst coating can support oxidation of particles. In a preferred embodiment, the ratio of the platinum-group metal concentration (PGM) of the TWC1 to the PGM of the GPF is from 1.1 to 10, preferably from 1.25 to 9, more preferably from 1.45 to 5, wherein the PGM is determined in g/ft3 of the volume of the device. This can be advantageous, because the TWC1 is located closer to the gasoline engine than the GPF. Thus, the TWC1 can reach the high temperature required for optimal catalytic performance more rapidly and for longer time periods. Due to the higher temperature, the catalytic performance of the TWC1 can be higher than that of the GPF especially under non-optimal operating conditions. For this reason, it can be advantageous to equip the TWC1 with a higher catalyst concentration than the GPF, such that a large portion of the gaseous pollutants is already removed in the TWC1. Further, it can be advantageous that the platinum-group metal concentration (PGM) of the GPF is lower than in the TWC1, because the GPF has to be equipped with less wash coat. As a result, the pressure drop in the GPF can be kept relatively low. Since the exhaust gas stream has to pass the filter walls in the GPF, control of the pressure drop is important, such that the performance of the engine is not impaired. Overall, due to the optimal distribution of PGM between the devices of the system, the overall amount of precious metals in the system can be kept relatively low, whilst a high exhaust gas purification efficiency and high engine performance is achieved. In a preferred embodiment, the platinum-group metal concentration (PGM) of the TWC1 is at least 40% greater than the PGM of the GPF, wherein the PGM is determined in g/ft3 of the volume of the device. In this embodiment, especially under non-optimal operating conditions, it can be advantageous that the catalytic performance of the TWC1 can be adjusted relatively high, whereas the pressure drop of the GPF can be kept relatively low such that a good engine performance can be maintained. In a preferred embodiment, the platinum-group metal concentration (PGM) of the TWC1 is greater than the sum of the PGM of the GPF and TWC2, wherein the PGM is determined in g/ft3 of the volume of the device. When the PGM of the TWC1 is adjusted accordingly, the overall system can especially have a high catalytic efficiency under non-optimal conditions. Since the TWC1 is located closer to the engine than the GPF and TWC2, it can reach its optimal high operating temperature more rapidly and for longer time periods, and has a higher relative catalytic performance. Therefore, it can be advantageous that a relatively high portion of the overall catalytic activity of the total system is concentrated in the TWC1, whilst a significantly lower portion of the catalytic activity is located in the GPF and TWC2, Overall, this can be acceptable, because the GPF is in contact with the pre-purified exhaust gas from the TWC1, which comprises significantly less gaseous pollutants than the original exhaust gas. Moreover, the TWC2 is only in contact with the pre-purified exhaust gas from the GPF, which only comprises residual, relatively small amounts of gaseous pollutants. Overall, a system can be provided in which the PGM is distributed between the three devices, such that gaseous and particulate pollutants are efficiently removed whilst the pressure drop is kept low and engine performance is maintained. In a preferred embodiment, the total amount of platinum-group metal of the TWC1 is from 1 g to 15 g, preferably from 2 g to 10 g. In a preferred embodiment, the total amount of platinum-group metal of the GPF is from 0 g to 5 g, preferably from 0.05 g to 5 g, more preferably from 1 g to 3 g. In a preferred embodiment, the total amount of platinum-group metal of the TWC2 is from 0.1 g to 2 g, preferably from 0.2 g to 1.5 g. Overall, an efficient removal of pollutants with minimum PGM costs can be achieved with the system when the total amount of platinum group metal is adjusted and distributed accordingly. In a preferred embodiment, the TWC1 comprises palladium and/or rhodium. In a preferred embodiment, the GPF comprises palladium, platinum, rhodium or mixtures thereof. Rhodium is especially efficient in removing NOx, whereas palladium is especially efficient in removing CO. Therefore, the use of these metals in these devices can be advantageous for efficient overall removal of pollutants from the exhaust gas. In a preferred embodiment, the percentage of rhodium of the total amount of platinum-group metal of the GPF is at least 10 wt. %, more preferably at least 20 wt. %, This can be advantageous for efficiently removing NOxin the GPF. In a preferred embodiment, the TWC2 comprises rhodium. In a preferred embodiment, the percentage of rhodium of the total amount of platinum-group metal of the TWC2 is at least 15 wt. %, more preferably at least 25 wt. %, it can be advantageous that the TWC2 comprises rhodium in such amounts in order to remove NOx, but also other impurities, such as CO, from the pre-purified exhaust gas, which is emitted from or not converted by the GPF. In a preferred embodiment, the TWC2 does not comprise platinum. It can be advantageous that the use of expensive platinum can be avoided in the TWC2, whilst an overall efficient removal of pollutants can be achieved. In a preferred embodiment, the wash coat load (WCL) of the TWC2 is greater than the WCL of the GPF, wherein the WCL is determined in g/l of the volume of the device. Generally, a high WCL in the GPF can lead to a high pressure drop, because the exhaust gas has to pass the inner filter walls of the GPF and the catalytic wash coat on the filter walls. According to the invention, it can be advantageous that the WCL of the GPF is relatively low, because the pressure drop of the GPF, and therefore of the whole exhaust gas purification system, can be kept low. In contrast, the exhaust gas usually does not traverse the filter walls of a three way catalyst device. Thus, additional wash coat in the TWC2 will generally not provide a comparable decrease of pressure drop as in the GPF. However, it is preferred that the GPF is provided with a wash coat having catalytic activity. Overall, an efficient overall system can be provided having high catalytic efficiency and low pressure drop. Further, a significant WCL of the TWC2 can be advantageous, because it can provide an efficient removal of all residual pollutants from the pre-purified exhaust gas not converted by or emitted from the GPF, especially when the GPF is regenerated. Thus, the overall system can provide an efficient removal of pollutants. Even further, the TWC2 is located relatively far from the gasoline engine. Thus, the TWC2 is subjected to and frequently operated at lower temperatures than the other upstream devices. Consequently, the TWC2 is less affected by aging and concomitant deterioration of catalyst performance. Thus, since the catalytic efficiency of the TWC2 can be relatively stable, it can be advantageous to provide the TWC2 with a relatively high amount of wash coat. In a preferred embodiment, the wash coat load (WCL) of the TWC2 is from 100 g/l to 300 g/l, preferably from 150 g/l to 280 g/l, more preferably from 175 g/l to 260 g/l. When the WCL of the TWC2 is adjusted accordingly, a relatively good overall removal of pollutants with the catalytic system is possible. Overall, the catalyst is used efficiently, because the TWC2 is located far away from the engine and less affected by aging than the GPF or TWC1. Further, such amounts of wash coat are suitable for providing an effective finishing of the pre-purified exhaust gas emitted from the GPF, whereby residual pollutants are removed. In a preferred embodiment, the wash coat load (WCL) of the GPF is from 0 g/l to 150 g/l, preferably from 30 g/l to 130 g/l, more preferably from 50 g/l to 110 g/l. When adapting the WCL of the GPF in such relatively low ranges, the pressure drop can be adjusted to be low. Further, the overall amount of catalyst in the system can be kept relatively low. The GPF, which is coated with a relatively low amount of wash coat, can efficiently remove residual pollutants from the TWC1, which comprises a relatively high WCL. In a preferred embodiment, the wash coat load (WCL) of the TWC1 is from 150 g/l to 350 g/l, preferably from 180 g/l to 310 g/l, more preferably from 200 g/l to 280 g/l. When the WCL of the TWC1 is used in such relatively high amounts, a good combination of high catalytic performance of the TWC1 with efficient removal of residual pollutants by the GPF and TWC2 is provided. It is also advantageous that the WCL of the TWC1 is adjusted within these relatively high ranges, because the TWC1 is located closest to the gasoline engine. Thus, it is heated more rapidly than the downstream devices and achieves the high optimal operation temperature more often and for longer time periods. Further, a high WCL typically confers higher aging stability to the TWC1, which is especially advantageous when the TWC1 is closed coupled to the engine and thus operated at higher temperatures Therefore, a relatively high wash coat load of the TWC1 can be advantageous for an effective initial and also total removal of pollutants. Overall, by adapting the WCL of the devices accordingly, an efficient use of total catalyst can be adjusted. Further, a relatively high catalytic efficiency of the TWC1 can be advantageous for diagnosis capability. Especially during on-board diagnosis, the catalytic performance is commonly carried out by monitoring the first catalytic device in the system. When the wash coat load and catalytic performance of the TWC1 is relatively high, on-board diagnosis can provide relatively good results in approximation when monitoring only the TWC1. Thereby, a relatively good correlation of the diagnosis result with real driving emissions is possible. In a preferred embodiment, the wash coat load (WCL) of the TWC1 is greater than the WCL of the TWC2, wherein the WCL is determined in of the volume of the device. This can be advantageous, because the upstream TWC1, which is located close to the gasoline engine, can be operated more efficiently and more often at a high temperature and achieves a greater catalytic efficiency at high operation temperature. Since the TWC2 only removes residual pollutants, it is appropriate that the WCL is lower than of the TWC1. However, it can be advantageous that a downstream TWC2 is present, which removes pollutants from the TWC1 and GPF, and which is less affected by aging than the TWC1. In the overall system, it can be advantageous that on-board diagnosis can be performed with the TWC1 and provides a reasonable correlation to total emissions. Overall, the TWC1 and TWC2 complement each other in the system and provide, together with the GPF between them, an unexpected combination of high filtration efficiency, high catalytic efficiency and low pressure drop. In one embodiment, the wash coat of the TWC1 is the same as for the TWC2. This means that the oxides comprised and concentrations thereof are the same in both wash coats. In another embodiment, the TWC1 and TWC2 comprise different wash coats. TWC catalysts include oxygen storage materials (OSM) such as ceria that have multivalent states which allows oxygen to be held and released under varying air to fuel ratios. Under rich conditions, when NOxis being reduced, the OSM provide a small amount of oxygen to consume unreacted CO and HC. Likewise, under lean conditions when CO and HC are oxidized, the OSM reacts with excess oxygen and/or NOx. As a result, even in the presence of an atmosphere that oscillates between fuel-rich and fuel-lean air to fuel ratios, there is conversion of HC, CO, and NOxall at the same (or at essentially all the same) time. In a preferred embodiment, the oxygen storage capacity (OSC) of the TWC2 is greater than the OSC of the GPF, wherein the OSC is determined in mg/l of the volume of the device in fresh state. This can be advantageous, because the TWC2 is located more distant from the gasoline engine and thus is generally receiving less heat from the gasoline engine. Therefore, the TWC2 is less affected by aging and concomitant undesired decrease of catalytic efficiency. When the OSC of the TWC2 is higher than of the GPF, an efficient continuous final removal of residual pollutants from the GPF can be achieved even at a relatively low temperature. Further, a relatively high OSC of the TWC2 can be advantageous, because emissions of CO and NOxfrom the GPF can be relatively high at least temporarily. Thus, it can be advantageous to efficiently control the oxygen level in the TWC2, such that relatively large amounts of oxygen can be stored in or released into the TWC2 to remove residual pollutants under different operation conditions. This can especially be advantageous when the OFF is regenerated. Gasoline particulate filters have to be regenerated at repetitive time intervals if their operating temperature is not sufficient for passive soot oxidation. During regeneration, the soot which has accumulated in the GPF since the last regeneration procedure is oxidized and converted into carbon dioxide. However, the conversion is often not quantitative, and significant amounts of side products such as CO and HC can also be formed in the GPF. To remove these in the downstream TWC2, a significant amount of additional oxygen may be required within a relatively short time window. A relatively high OSC in the TWC2 can provide sufficient oxygen to remove such pollutants also during regeneration of the GPF. Even further, a high OSC in the TWC2 can be advantageous for efficient removal of residual NOxunder lean operation conditions. A TWC2 having a high OSC can bind a large amount of oxygen under lean operation conditions. If the OSC would be too low, too much unbound oxygen can be present under lean conditions and the reduction of NOxto N2can be impaired. Moreover, a relatively low OSC of the GPF can be advantageous, because less catalyst coating can be provided in the GPF, which correlates with a relatively low pressure drop in the GPF. Overall, a good combination of high filtration efficiency, high catalytic efficiency and low pressure drop can be achieved when adjusting the OSC of the TWC2 and GPF accordingly. In a preferred embodiment, the oxygen storage capacity (OSC) of the TWC1 is higher than the OSC of the GPF, wherein the OSC is determined in mg/l of the volume of the device in fresh state. In a preferred embodiment, the OSC of the TWC1 is at least 40% greater than the OSC of the GPF. A higher OSC of the TWC1 can be advantageous, because it can support a relatively high catalytic efficiency of the TWC1. The TWC1 is located closest to the gasoline engine and thus is operated more frequently at optimal high temperature than the downstream GPF, and especially than the even more remote TWC2. Therefore, an efficient catalytic reaction can occur more easily and more frequently in the TWC1 than in the downstream devices. In the overall system, it can be generally advantageous if a relatively high catalytic turnover is mediated by the TWC1. Then, residual pollutants emitted from the TWC1 can be removed by the downstream devices, which can have a lower OSC. Moreover, a relatively high OSC of the TWC1 can be advantageous when the engine is operated alternately under rich operation conditions with lambda<1 and lean operation conditions with lambda>1 for short intervals of time. Such an operation mode is known as wobbling or as wobble operation. In a wobbling mode, a high OSC can be advantageous, because oxygen can be efficiently stored under lean operation conditions and released into the reaction under rich operation conditions. Accordingly, a high OSC in the TWC1 supports an efficient overall removal of pollutants under such conditions. In contrast, a high OSC of the GPF is less relevant for operation under wobble conditions, because the major portion of the pollutants was already removed in the TWC1, such that the absolute concentrations of the pollutants are comparably low in the GPF. Even further, a high OSC in the TWC1 can be advantageous for efficient removal of NOxunder lean operation conditions. A TWC1 having a high OSC can bind a large amount of oxygen under lean operation conditions. If the OSC would be too low, too much unbound oxygen can be present under lean conditions, and the reduction of NOxto N2can be impaired. Further, a high OSC in the TWC1 can be advantageous for diagnosis capability. Especially on-hoard diagnosis is commonly carried out with the first catalytic device. When the upstream TWC1 has a high catalytic efficiency, the result of on-board diagnosis at the TWC1 will provide a reasonable indication of final emissions or real driving emissions (RDE). In a preferred embodiment, the oxygen storage capacity (OSC) of the TWC1 is from 400 mg to 1250 mg, preferably from 500 mg to 900 mg. This can be advantageous, because a high catalytic efficiency can be achieved at the TWC1 when the OSC is adjusted accordingly. As outlined above, this can be advantageous for overall catalytic efficiency, operation in the wobbling mode and diagnosis capability. In a preferred embodiment, the ratio Vcat/Vengis at least 1, wherein Vcatis the total catalyst volume of all devices and Vengis the engine displacement of the gasoline engine. Thus, the total catalyst volume is at least the sum of the volumes of the TWC1, TWC2 and GPF. As used herein, the catalyst volume of a device is the overall volume, and not only the internal void volume. A ratio of 1 or more is advantageous, because a relatively high catalyst volume of all devices can provide a high catalytic performance. The volume of the engine can approximately be correlated to the amount of exhaust gas emitted during operation. If the total catalyst volume would be smaller than the engine volume, the efficiency of the exhaust gas purification system can be too low, especially under high mass flows that are observed under real driving conditions. In order to achieve a high catalytic efficiency, a relatively high catalyst concentration may then have to be provided in the catalytic devices, which could lead to an undesired increase of the pressure drop. In a preferred embodiment, the ratio Vcal/Vengis from 1 to 5, preferably from 1.1 to 4, more preferably from 1.2 to 3.5. If the catalyst volume would be higher, the heat transfer from the gasoline engine to the catalytic devices could become insufficient. Generally, an efficient heat transfer from the gasoline engine to the downstream catalytic devices is required, such that the devices can attain the optimal high operation temperature. Typically, such catalytic devices are operated at a temperature of several hundred degrees Celsius for an optimal performance and catalytic conversion. If the temperature is below the optimal temperature, the catalytic turnover can be decreased. Further, a compact integration of the catalytic system into a vehicle is difficult, when the total catalytic volume is too high. In a preferred embodiment, the volume of the TWC1 (VTWC1) is from 20% to 50%, preferably from 30% to 40%, of the total catalyst volume Vcat. In this embodiment, it is preferred that the volume of the TWC1 is larger than the volume of the TWC2. Overall, a relatively high volume of the TWC1 can be advantageous, because the TWC1 can be provided with a relatively high catalytic efficiency. Accordingly, a major portion of the gaseous pollutants from the gasoline engine can be removed in the TWC1, which is located relatively close to the engine and attains a relatively high temperature more easily and frequently. This is especially advantageous for efficient removal of pollutants under dynamic driving conditions, for example in urban traffic or after a cold start of the engine. Further, diagnosis capability, especially for on-board diagnosis of catalytic efficiency, is usually carried out at the upstream device, in this case the TWC1. Therefore, a high efficiency of the TWC1 allows relatively good monitoring of the overall catalytic efficiency, In a preferred embodiment, the volume of the GPF (VGPF) is from 30% to 60%, preferably from 40% to 55%, of the total catalyst volume Vcat. In a specific embodiment, the total volume of the GPF is larger than the total volume of the TWC1 and/or of the TWC2. A relatively high volume of the GPF can be advantageous, because a relatively high volume can be associated with a relatively low pressure drop. If the volume of the GPF would be too low, the pressure drop could increase, which could yield to inefficient operation of the engine and increased carbon dioxide emissions. A relatively high volume of the GPF can be especially advantageous, if the GPF is a catalytic GPF, which is provided with a catalyst wash coat, preferably a TWC washcoat, which reduces the void volume in the device through which the exhaust gas can flow. A relatively high volume of the OFF can also be advantageous for efficient storage of particles and for efficient regeneration, when accumulated soot particles are removed under oxidizing conditions. In a preferred embodiment, the volume of the TWC2 (VTWC2) is from 10% to 40%, preferably from 15% to 35%, of the total catalyst volume Vcat. A lower volume of the TWC2, when compared to the TWC1 and/or GPF, can be advantageous, because removal of residual pollutants from the OFF may require less catalyst and thus catalyst volume in the TWC2, Therefore, an efficient overall system can be provided at relatively low costs and with favourable distribution of catalyst throughout the three devices. In a preferred embodiment, the ratio of the smallest diameter of the GPF to the length of the GPF is from 0.7 to 3, preferably from 0.75 to 1.6. When the dimensions of the GPF are adjusted accordingly, a relatively efficient particle filtration and catalyst performance could be achieved while maintaining a relatively low backpressure. In a highly preferred embodiment, the system comprises a turbocharger positioned upstream from the TWC1. A turbocharger is a turbine-driven forced induction device that increases an internal combustion engine's efficiency and power output by forcing extra air into the combustion chamber. Therefore, a more efficient exhaust gas purification system can be required if a turbocharger is present. The highly efficient inventive catalytic system is especially suitable for purifying exhaust gas from a gasoline engine and a turbocharger. Preferably, the turbocharger is the only additional device between the gasoline engine and the TWC1. Preferably, the distance from the outlet surface of the turbocharger to the inlet surface of the TWC1 is from 1 cm to 40 cm, preferably from 2 cm to 30 cm, more preferably from 2 cm to 20 cm. Preferably, the distance is less than 10 cm or less than 5 cm. When the dimensions of the turbocharger and TWC1 are adapted accordingly, a close-coupled operation of the TWC1 with the gasoline engine is possible. Then, heat can be transferred more rapidly and efficiently from the engine to the TWC1 and downstream catalyst devices. This can be advantageous, because the catalytic reaction in the TWC1 and downstream devices is generally more efficient at high temperature. Further, rapid heat transfer supports an efficient catalytic reaction after cold-start and under dynamic driving conditions, for example in urban traffic. Moreover, a close-coupled system can be integrated directly in the space behind the gasoline engine. Accordingly, it is not necessary to integrate the TWC1, or downstream catalytic devices which are also close-coupled, into the underbody of a vehicle. Thereby, a compact integrated catalyst system can be provided. Further, close-coupling of the TWC1 and the OFF to the engine generally can also provide a higher catalytic efficiency of the GPF and more efficient regeneration of the GPF. In a preferred embodiment, the distance of the outlet surface of the TWC1 to the inlet surface of the GPF is from 1 cm to 60 cm, preferably from 2 cm to 50 cm, more preferably from 3 cm to 40 cm. Preferably, the distance is less than 20 cm or less than 10 cm. When keeping the distance between the TWC1 and GPF relatively short, a close-coupled connection of the GPF with the gasoline engine is possible. Thereby, heat can be transferred more efficiently and rapidly into the GPF, but also the downstream TWC2. Further, the GPF can be integrated more compactly into a vehicle. Further, the catalyst system can be regenerated more efficiently at high temperature and can have a higher catalytic turnover. In a preferred embodiment, the distance of the outlet surface of the GPF to the inlet surface of the TWC2 is from 0 cm to 120 cm, preferably from 1 cm to 110 cm, more preferably from 2 cm to 100 cm. Preferably, the distance is less than 20 cm or less than 10 cm. Thereby, a close-coupled system is obtainable with additional advantages as described above. Overall, it is preferred that all devices of the system are close-coupled to each other and to the gasoline engine. In a preferred embodiment, the TWC1 comprises at least two different wash coat layers. In a further preferred embodiment, the TWC2 comprises one or two different wash coat layers. Preferably, the wash coat layers are laid over each other. In a preferred embodiment, different wash coat layers can be located at different surfaces of the porous walls of the GPF. When combining different wash coat layers, catalytic coatings can be combined which have different catalytic efficiency, resulting in an overall system which is effective in removing different fractions of pollutants. In a further embodiment, the catalytic efficiency of the TWC1 is greater than that of the GPF with regard to removal of NOx, CO and/or hydrocarbons, when performance of the GPF is determined under the same conditions as for the TWC1. This means that the performance of the GPF is determined without the upstream TWC1, This can be advantageous, because the TWC1 is closer to the engine and can be operated more efficiently at a higher temperature. Further, a high wash coat load in the TWC1 affects pressure drop less significantly than high wash coat load in the OFF, because the exhaust gas in the TWC1 does not have to traverse monolith filter walls. In a further embodiment, the catalytic performance of the GPF is greater than that of the TWC2 with regard to removal of NOx, CO and/or hydrocarbons, when performance of the TWC2 is determined under the same conditions as for the GPF, This means that the performances of the GFP and TWC2 are determined without further upstream exhaust gas purification devices. This can be advantageous, because the levels of gaseous pollutants in the GPF can be higher than in the pre-purified exhaust gas which enters the TWC2. Accordingly, relatively efficient removal of pollutants in the GPF can be combined with final removal of residual pollutants in the TWC2. Overall, a system can be provided with effective combination and adaptation of filtration efficiency, TWC efficiency and low pressure drop in the three devices, with a highly efficient distribution of the catalytic material throughout the catalyst system. Preferably, the purified exhaust gas emitted from the TWC2 comprises the following levels of pollutants (in mg/km):CO: less than 1000, preferably less than 500, more preferably less than 300THC: less than 100, preferably less than 50, more preferably less than 30NOx: less than 60, preferably less than 40, more preferably less than 30PM: less than 0.005, preferably less than 0.002, more preferably less than 0.001 Preferably, the particle number (PN) is less than 6×1011, preferably less than 5×1011, Preferably, these pollutant levels are determined according to the standard tests defined in EURO6, test cycle WLTP (see EU commission regulation 2007/715 and 2008/692 and regulations based thereon 2017/1151, 2017/134). Subject of the invention is also a method for purifying exhaust gas emitted from a gasoline engine, comprising the steps of:(a) providing a gasoline engine and an exhaust gas purification system of the invention, and(b) passing exhaust gas emitted from the gasoline engine through the system, such that the exhaust gas is purified by the system. As outlined above, method uses the exhaust gas purification system as described above, which is suitable for gasoline engines. It is adapted to the specific exhaust gas and pollutants emitted from gasoline engines, which is different than exhaust gas from diesel engines. Subject of the invention is also the use of the inventive exhaust gas purification system for purifying exhaust gas from a gasoline engine. The invention comprises the following embodiments:1. An exhaust gas purification system for a gasoline engine, comprising in consecutive order the following devices:a first three-way-catalyst (TWC1), a gasoline particulate filter (GPF) and a second three-way-catalyst (TWC2),wherein the platinum-group metal concentration (PGM) of the GPF is at least 40% greater than the PGM of the TWC2, wherein the PGM is determined in g/ft3 of the volume of the device.2. The system according to the preceding embodiment, wherein the ratio of the platinum-group metal concentration (PGM) of the TWC1 to the PGM of the GPF is from 1.1 to 10, preferably from 1.25 to 9, more preferably from 1.45 to 5, wherein the PGM is determined in g/ft3 of the volume of the device.3. The system according to at least one of the preceding embodiments, wherein the platinum-group metal concentration (PGM) of the TWC1 is at least 40% greater than the PGM of the GPF, wherein the PGM is determined in g/ft3 of the volume of the device.4. The system according to at least one of the preceding embodiments, wherein the platinum-group metal concentration (PGM) of the TWC1 is greater than the sum of the PGM of the GPF and TWC2, wherein the PGM is determined in g/ft3 of the volume of the device.5. The system according to at least one of the preceding embodiments, wherein the total amount of platinum-group metal of the TWC1 is from 1 g to 15 g.6. The system according to at least one of the preceding embodiments, wherein the total amount of platinum-group metal of the GPF is from 0 g to 5 g, preferably from 0.05 g to 5 g.7. The system according to at least one of the preceding embodiments, wherein the total amount of platinum-group metal of the TWC2 is from 0.1 g to 2 g.8. The system according to at least one of the preceding embodiments, wherein the TWC1 comprises palladium and/or rhodium.9. The system according to at least one of the preceding embodiments, wherein the GPF comprises palladium, platinum, rhodium or mixtures thereof.10. The system according to at least one of the preceding embodiments, wherein the percentage of rhodium of the total amount of platinum-group metal of the GPF is at least 10 wt. %.11. The system according to at least one of the preceding embodiments, wherein the TWC2 comprises rhodium.12. The system according to at least one of the preceding embodiments, wherein the percentage of rhodium of the total amount of platinum-group metal of the TWC2 is at least 15 wt. %.13. The system according to at least one of the preceding embodiments, wherein the TWC2 does not comprise platinum.14. The system according to at least one of the preceding embodiments, wherein the wash coat load (WCL) of the TWC2 is greater than the WCL of the OFF, wherein the WCL is determined in g/l of the volume of the device.15. The system according to at least one of the preceding embodiments, wherein the wash coat load (WCL) of the TWC2 is from 100 to 300 g/l, preferably from 150 g/l to 280 g/l, more preferably from 175 g/l to 260 g/l.16. The system according to at least one of the preceding embodiments, wherein the wash coat bad (WCL) of the OFF is from 0 g/l to 150 g/l, preferably from 30 g/l to 130 g/l, more preferably from 50 g/l to 110 g/l.17. The system according to at least one of the preceding embodiments, wherein the wash coat load (WCL) of the TWC1 is from 150 g/l to 350 g/l, preferably from 180 g/l to 310 g/l, more preferably from 200 g/l to 280 g/l.18. The system according to at least one of the preceding embodiments, wherein the wash coat load (WCL) of the TWC1 is greater than the WCL of the TWC2, wherein the WCL is determined in g/l of the volume of the device.19. The system according to at least one of the preceding embodiments, wherein the oxygen storage capacity (OSC) of the TWC2 is greater than the OSC of the GPF, wherein the OSC is determined in mg/l of the volume of the device.20. The system according to at least one of the preceding embodiments, wherein the oxygen storage capacity (OSC) of the TWC1 is greater than the OSC of the TWC2, wherein the OSC is determined in mg/l of the volume of the device.21. The system according to at least one of the preceding embodiments, wherein the oxygen storage capacity (OSC) of the TWC1 is from 400 mg to 1250 mg, preferably from 500 mg to 900 mg.22. The system according to at least one of the preceding embodiments, wherein the ratio Vcat/Vengis at least 1, wherein Vcatis the total catalyst volume of all devices and Vengis the engine displacement of the gasoline engine.23. The system according to at least one of the preceding embodiments, wherein the ratio Vcat/Vengis from 1 to 5, preferably from 1.1 to 4, more preferably from 1.2 to 3.5.24. The system according to at least one of the preceding embodiments, wherein the volume of the TWC1 (VTWC1) is from 20% to 50% of the total catalyst volume Vcat, preferably from 30% to 40%.25. The system according to at least one of the preceding embodiments, wherein the volume of the GPF (VGPF) is from 30% to 60% of the total catalyst volume Vcat, preferably from 40% to 55%.26. The system according to at least one of the preceding embodiments, wherein the volume of the TWC2 (VTWC2) is from 10% to 40% of the total catalyst volume Vcat, preferably from 15% to 35%.27. The system according to at least one of the preceding embodiments, wherein the ratio of the smallest diameter of the GPF to the length of the GPF is from 0.7 to 3, preferably from 0.75 to 1.6.28. The system according to at least one of the preceding embodiments, wherein the system comprising a turbocharger positioned upstream of the TWC1, wherein the distance of the outlet surface of the turbocharger to the inlet surface of the TWC1 is from 1 cm to 40 cm, preferably from 2 cm to 30 cm, more preferably from 2 cm to 20 cm.29. The system according to at least one of the preceding embodiments, wherein the distance of the outlet surface of the TWC1 to the inlet surface of the GPF is from 1 cm to 60 cm, preferably from 2 cm to 50 cm, more preferably from 3 cm to 40 cm.30. The system according to at least one of the preceding embodiments, wherein the distance of the outlet surface of the GPF to the inlet surface of the TWC2 is from 0 cm to 120 cm, preferably from 1 cm to 110 cm, more preferably from 2 cm to 100 cm.31. The system according to at least one of the preceding embodiments, wherein the TWC1 comprises at least two different wash coat layers.32. The system according to at least one of the preceding embodiments, wherein the TWC2 comprises one or two different wash coat layers.33. The system according to at least one of the preceding embodiments, wherein the catalytic performance of the TWC1 is greater than that of the GPF with regard to removal of NOx, CO and/or hydrocarbons, when performance of the GPF is determined under the same conditions as for the TWC1.34. The system according to at least one of the preceding embodiments, wherein the catalytic performance of the GPF is greater than that of the TWC2 with regard to removal of NOx, CO and/or hydrocarbons, when performance of the TWC2 is determined under the same conditions as for the GPF.35. A method for purifying exhaust gas emitted from a gasoline engine, comprising the steps of:(a) providing a gasoline engine and an exhaust gas purification system of any of the preceding embodiments, and(b) passing exhaust gas emitted from the gasoline engine through the system, such that the exhaust gas is purified in the system.36. Use of an exhaust gas purification system of any of the preceding embodiments for purifying exhaust gas from a gasoline engine. | 51,295 |
11859527 | PREFERRED EMBODIMENTS OF THE INVENTION InFIG.1, indicated as a whole by the number1is a boosted internal combustion engine provided with an exhaust system2for the exhaust gases in a motor vehicle (not illustrated) and having a number of cylinders3, each of which is connected to an intake manifold4and to an exhaust manifold5by at least one respective exhaust valve (not illustrated). Also, according to a preferred embodiment, the following disclosure finds advantageous yet not exclusive application in the case of an internal combustion engine1in which the fuel fed is gasoline. The intake manifold4receives air coming from the external environment through an intake duct6, which is provided with an air filter7for the flow of fresh air and is regulated by a throttle valve8. A mass air flow sensor9(better known as Air Flow Meter) is also arranged along the intake duct6downstream of the air filter7. The exhaust manifold5is connected to an exhaust duct10that feeds the exhaust gases produced by combustion to the exhaust system2, which emits the gases produced by combustion into the atmosphere. The boosting system of the internal combustion engine1comprises a turbocompressor11provided with a turbine12, which is arranged along the exhaust duct10to rotate at high speed under the action of the exhaust gases expelled from the cylinders3, and a compressor13, which is arranged along the intake duct6and is mechanically connected to the turbine12to be dragged into rotation by said turbine12so as to increase the pressure of the air present in the intake duct6. The gas exhaust system2is provided with an exhaust gas after-treatment system14comprising a precatalytic converter15arranged along the exhaust duct10, downstream of the turbocompressor11and a particulate filter16(also known as Gasoline Particulate Filter) also arranged along the exhaust duct10, downstream of the precatalytic converter. According to a preferred embodiment, the exhaust after-treatment system14is provided with a catalytic converter17arranged along the exhaust duct10, upstream of the particulate filter16. According to a preferred embodiment, the catalytic converter17and the particulate filter16are arranged one after the other inside a common tubular container. According to a first variant, the internal combustion engine1is also provided with a linear oxygen sensor18of the UHEGO or UEGO type housed along the exhaust duct10and interposed between the turbocompressor11and the precatalytic converter15so as to detect the air/fuel ratio (or titer) of the exhaust gases (providing a linear output indicating the content of oxygen in the exhaust gases) downstream of the turbocompressor11and upstream of the precatalytic converter15. The internal combustion engine is also provided with a lambda sensor19intended to provide a binary on/off type output indicating whether the exhaust gases titer is above or below the stoichiometric value, housed along the exhaust duct10and interposed between the precatalytic converter15and the assembly defined by the catalytic converter17and by the particulate filter16to detect the oxygen concentration inside the exhaust gases downstream of the precatalytic converter15; and finally, a lambda sensor20suited to provide a binary on/off type output indicating whether the exhaust gases titer is above or below the stoichiometric value, housed along the exhaust duct and arranged downstream of the assembly defined by the catalytic converter17and by the particulate filter16to detect the oxygen concentration inside the exhaust gases downstream of the assembly defined by the catalytic converter17and the particulate filter16. According to a second variant illustrated inFIG.2, the internal combustion engine1is also provided with a lambda sensor19* suited to provide a binary on/off type output indicating whether the exhaust gases titer is above or below the stoichiometric value, housed along the exhaust duct10and interposed between the turbocompressor11and the precatalytic converter15to detect the air/fuel ratio (or titer) of the exhaust gases downstream of the turbocompressor11and upstream of the precatalytic converter15. The internal combustion engine1is also provided with a UHEGO or UEGO type linear oxygen sensor18* housed along the exhaust duct10and interposed between the precatalytic converter15and the assembly defined by the catalytic converter17and by the particulate filter16to detect the oxygen concentration inside the exhaust gases downstream of the precatalytic converter15(a linear output indicating the content of oxygen in the exhaust gases); and lastly, a lambda sensor20suited to provide a binary on/off type output indicating whether the exhaust gases titer is above or below the stoichiometric value, housed along the exhaust duct10and arranged downstream of the assembly defined by the catalytic converter17and by the particulate filter16to detect the oxygen concentration inside the exhaust gases downstream of the assembly defined by the catalytic converter17and by the particulate filter16. The exhaust gas after-treatment system14then comprises a burner21suited to introduce exhaust gases (and consequently heat) into the exhaust duct10so as to speed up the heating of the precatalytic converter15and/or of the catalytic converter17and so as to facilitate the regeneration of the particulate filter16. According to what is better illustrated inFIG.3, a combustion chamber22is defined inside the burner21, the chamber receives fresh air (i.e., air coming from the outside environment) through an air feeding circuit23provided with a pumping device24that feeds the air by means of a duct25regulated by an on/off type shut-off valve26. The combustion chamber22also receives fuel from an injector27designed to cyclically inject fuel inside the combustion chamber22. In addition, a spark plug28is coupled to the burner21to determine the ignition of the mixture present inside said combustion chamber22. The internal combustion engine1then comprises a fuel feeding circuit29provided with a pumping device30that feeds the fuel by means of a duct31. Lastly, the internal combustion engine1comprises a control system32which is adapted to oversee the operation of said internal combustion engine1. The control system32comprises at least one electronic control unit (normally referred to as an “ECU”—“Electronic Control Unit”), which oversees the operation of the various components of the internal combustion engine1. The spark plug28is operated by the electronic control unit ECU to make a spark between its electrodes and therefore determine the ignition of the gases compressed inside the combustion chamber22. The control system32also comprises a plurality of sensors connected to the electronic control unit ECU. The sensors comprise, in particular, a sensor33for the temperature and pressure of the air flow fed to the burner21preferably housed along the duct25; a sensor34for the temperature and pressure of the exhaust gases exiting the burner21housed along an outlet duct35for discharging the exhaust gases exiting the burner21into the exhaust duct10; a sensor36for the pressure of fuel fed to the burner21housed along the duct31; and a sensor37for the pressure and temperature of the air flow fed to the pumping device24. The electronic control unit ECU is also connected to the UHEGO or UEGO type linear oxygen sensor18,18* and to the lambda sensors19,19*,20. According to a first embodiment illustrated inFIG.1, the burner21is arranged so as to introduce the exhaust gases into the exhaust duct10upstream of the UHEGO or UEGO type linear oxygen sensor18and upstream of the precatalytic converter15. According to a second embodiment illustrated inFIG.2, the burner21is arranged so as to introduce the exhaust gases into the exhaust duct10upstream of the UHEGO or UEGO type linear oxygen sensor18* and upstream of the assembly defined by the catalytic converter17and by the particulate filter16. The method implemented by the electronic control unit ECU to control the burner21is described in the following. Firstly, the strategy described in the following disclosure may be implemented exclusively when the UHEGO or UEGO type linear oxygen sensor18,18* is hit exclusively by the exhaust gases produced by the burner21(in other words, it is necessary that the UHEGO or UEGO type linear oxygen sensor18,18* is not hit by the exhaust gases produced by the internal combustion engine1). Therefore, the condition of enabling the control strategy for the burner21is that said burner21is turned on and the internal combustion engine1is instead turned off. In particular, the following two conditions may occur alternatively: a) burner21turned on with the “cold” exhaust system2(i.e., with a detected temperature below a limit value, ranging from 180° C. to 200° C.); or b) burner21turned on with the “hot” exhaust system2(i.e., with a detected temperature above a limit value, ranging from 180° C. to 200° C.) The condition a) may occur in any of the following cases: a1) the burner21is turned on when the door of the driver of the motor vehicle is opened (the opening is detected by means of a sensor or when the door is unlocked by remote control or even when the smart key is detected in proximity to the vehicle); a2) the burner21is turned on when the motor vehicle is a hybrid vehicle that is started in electric mode and the internal combustion engine1has not been turned on yet after the motor vehicle has been started; a3) the burner21is turned on when the vehicle is a hybrid vehicle running in electric mode and the electronic control unit ECU provides for switching to thermal mode (for example, in the case where the State Of Charge of a storage system is not sufficient to proceed in electric mode); in this case, the burner21is turned on about 3 to 5 seconds before the start of the internal combustion engine1. It is clear that, alternatively, in the case where the burner21is arranged so as to introduce the exhaust gases into the exhaust duct10upstream of the UHEGO or UEGO type linear oxygen sensor18* and upstream of the assembly defined by the catalytic converter17and by the particulate filter16(in other words, in the case where the burner21is interposed between the precatalytic converter15and the assembly defined by the catalytic converter17and by the particulate filter16), the strategy described in the following disclosure may also be implemented in the case where the internal combustion engine1is turned on since the exhaust gases produced by the internal combustion engine1have already passed through the precatalytic converter15. The burner21is then turned off if any of the following conditions occur:a temperature of the exhaust system2above a limit value ranging from 180° C. to 200° C. is detected; orwhen a predetermined amount of time has elapsed since the burner21was turned on; orin the case where the estimated energy supplied, for example, by means of the integral of the fuel flow rate exceeds a threshold value;in the case where no passenger is detected to be present on board the motor vehicle for a predetermined amount of time by means of at least one recognition device housed in the passenger compartment (such as, for example, a sensor in a seat of the driver of the motor vehicle, or a sensor of the seat belt of the driver of the motor vehicle). The condition b) may, on the other hand, occur in any of the following cases: b1) the burner21is turned on when the motor vehicle is a hybrid vehicle running in electric mode with the internal combustion engine1turned off; b2) the burner21is turned on during the release phase with the open clutch; and b3) the burner21is turned on during all the stopping phases of the motor vehicle; for example, the burner21is turned on during the stopping phases for a motor vehicle provided with the “Start and Stop” system, during parking manoeuvres of the motor vehicle, or even during the “after run” phase that allows the ventilation to be activated after the internal combustion engine1is turned off. The burner21is then turned off in the case where any of the following conditions occur: c) the internal combustion engine1is turned on; d) a predetermined amount of time has elapsed since the burner21was turned on; or e) the adaptive strategy outlined in the following disclosure has been completed. The strategy implemented by the electronic control unit ECU to operate the burner21is described below. Firstly, the electronic control unit ECU is designed to calculate the thermal power POBJrequired to reach the nominal operating temperature TCAT_OBJof the precatalytic converter15or the catalytic converter17and obtained with the objective value λOBJof the air/fuel ratio. To calculate the thermal power POBJ, it should be considered that the objective is to heat the precatalytic converter15or the catalytic converter17from an initial temperature T0up to the nominal operating temperature TCAT_OBJ; the heat QCATrequired to allow this temperature increase may be calculated as follows: QCAT=CCAT*MCAT*(TCAT_OBJ−T0) where CCATis the specific heat of the precatalytic converter15or the catalytic converter17and MCATrepresents the mass of the precatalytic converter15or the catalytic converter17(in essence, the product CCAT*MCATrepresents the thermal capacity of the precatalytic converter15or the catalytic converter17). In order to heat the precatalytic converter15or the catalytic converter17in an amount of time Δt and taking into account heat losses QDISS(by convection, gases leaving the catalytic converter, etc.), the thermal capacity POBJrequired is therefore given by: POBJ=(QCAT+QDISS)/Δt The thermal power Ptreleased by the combustion in the burner21with an air flow {dot over (m)}Aand titer λ may instead be calculated as follows: Pt={dot over (m)}A/λST*[1/(MAX(1,λ)*Hi*ηc−(1/MIN(λ,1)−1)*Hv] where λSTis the stoichiometric air/fuel ratio; λ is the combustion titer; {dot over (m)}Ais the air mass flow rate; Hiis the lower heating power of the fuel; Hvis the latent heat of vaporization of the fuel; and ηcis the combustion efficiency. Therefore, once the combustion air/fuel ratio (or titer) A is defined, the air flow rate {dot over (m)}Arequired to heat the precatalytic converter15or the catalytic converter17from an initial temperature T0to the nominal operating temperature TCAT_OBJmay be calculated, in the case where the internal combustion engine1is turned off, as follows: {dot over (m)}A=(CCAT*MCAT*(TCAT_OBJ−T0)+QDISS)/Δt)*λST/[1/(MAX(1,λ)*Hi*ηc−(1/MIN(λ,1)−1)*Hv] In the case where the internal combustion engine1is turned on, the contribution due to the heat QENGINE(positive if supplied or negative if subtracted) generated for the exchange of exhaust gases may be added as follows: {dot over (m)}A=(CCAT* MCAT*(TCAT_OBJ−T0)++QDISS−QENGINE)/Δt)*λST/[1/(MAX(1,λ)*Hi*ηc−(1/MIN(λ,1)−1)*Hv] Depending on the thermal power POBJrequired to reach the nominal operating temperature TCAT_OBJof the precatalytic converter15or of the catalytic converter17, the electronic control unit ECU determines both the objective air flow rate {dot over (m)}A_OBJand the nominal fuel flow rate {dot over (m)}F_N. According to a first variant, the pumping device24is regulated by controlling the number N of revolutions while the shut-off valve26is of the on/off type. The electronic control unit ECU is then designed to determine the objective air flow rate {dot over (m)}A_OBJand the nominal fuel flow rate {dot over (m)}F_N, which are obtained by operating the pumping device24, the shut-off valve26, the pumping device30and the injector27. According to what is illustrated schematically inFIG.4, the objective air flow rate {dot over (m)}A_OBJis provided at input to a map (typically provided by the manufacturer of the pumping device24) together with further quantities that comprise the ambient pressure PATMand the ambient temperature TATMprovided by the sensor37and the pressure PAof the air in the duct25provided by the sensor33. The map provides at output the nominal number NNOMof revolutions with which to operate the pumping device24. However, the actual number N of revolutions with which to operate the pumping device24is defined by the sum of the nominal number NNOMof revolutions and two further contributions. In particular, the nominal number NNOMof revolutions with which to operate the pumping device24represents the open-loop contribution and is precisely generated using the experimentally derived control map; while the closed-loop contribution NCLis provided by means of a PID controller which tries to zero an error in the air/fuel ratio, namely, a difference between the objective value λOBJof the air/fuel ratio and the actual value λ of the air/fuel ratio measured by the UHEGO or UEGO type linear oxygen sensor18,18*. The third contribution NADATis also determined depending on the integral action of the PID controller under stationary conditions (i.e., with stationary air flow rate {dot over (m)}A and fuel flow rate {dot over (m)}F). According to what is illustrated inFIG.6, the third contribution NADATwith which to operate the pumping device24is then used to update the map used previously to determine the nominal number NNOMof revolutions. In particular, the third contribution NADATis provided at input to the map together with further quantities that comprise the ambient pressure PATMand the ambient temperature TATMprovided by the sensor37and the pressure PAof the air in the duct25provided by the sensor33. The map provides at output the updated value of the estimated air flow rate {dot over (m)}A. In the case where the sum of the closed-loop contribution NCLand of the third contribution NADATis greater than a calibratable threshold value THR1, a breakdown or fault is diagnosed. According to a second variant, the pumping device24is not regulated by controlling the number N of revolutions while the shut-off valve26is produced with the variable/adjustable passage section (in other words, the shut-off valve26is not of the on/off type). In this case, a pressure sensor38is also provided in the duct25downstream of the shut-off valve26to detect the pressure of the air being fed to the burner21. The electronic control unit ECU is therefore designed to determine the objective air flow rate {dot over (m)}A_OBJand the nominal fuel flow rate {dot over (m)}F_Nthat are obtained by operating the shut-off valve26, the pumping device30and the injector27. According to what is illustrated schematically inFIG.7, the objective air flow rate {dot over (m)}A_OBJis provided at input to a map (typically provided by the manufacturer of the shut-off valve26) together with further quantities that comprise the pressure PAand the temperature TAof the air provided by the sensor33and the pressure PBURNof the air being fed to the burner21provided by the sensor38. The map provides at output the nominal passage section αNOMwith which to operate the shut-off valve26. The actual passage section αOBJwith which to operate the shut-off valve26is, however, defined by the sum of the nominal passage section αNOMand two further contributions. In particular, the nominal passage section αNOMwith which to operate the shut-off valve26represents the open-loop contribution and is precisely generated using the experimentally derived control map. In the case where the ratio between the pressure PBURNof the air being fed to the burner21and the pressure PAof the air is less than or equal to a threshold value THR, the closed-loop contribution αCLis provided by means of a PID controller which tries to zero an error in the air/fuel ratio, namely, a difference between the objective value λOBJof the air/fuel ratio and the actual value A of the air/fuel ratio measured by the UHEGO or UEGO type linear oxygen sensor18,18*. The third contribution αADATis also determined depending on the integral action of the PID controller under stationary conditions (i.e., with stationary air flow rate {dot over (m)}A and fuel flow rate {dot over (m)}F). According to what is illustrated inFIG.8, in the case where the ratio between the pressure PBURNof the air being fed to the burner21and the pressure PAof the air in the duct25is less than the threshold value THR, the third contribution αADATwith which to operate the shut-off valve26is used to update the map used previously to determine the nominal passage section αNOMwith which to operate the shut-off valve26. In particular, the third contribution αADATis provided at input to the map together with further quantities that comprise the pressure PBURNof the air being fed to the burner21, the pressure PAand the temperature TAof the air in the duct25. The map provides at output the updated value of the air flow rate {dot over (m)}A_RPL. In the case where the ratio between the pressure PBURNof the air being fed to the burner21and the pressure PAof the air in the duct25is greater than the threshold value THR, the value VBATis instead provided at input to the map together with further quantities that comprise the ambient pressure PATMand the ambient temperature TATMprovided by the sensor37and the pressure PAof the air in the duct25provided by the sensor33. The map provides at output the nominal value of the air flow rate {dot over (m)}A_NOM. However, the air flow rate {dot over (m)}A_RPHis defined by the sum of the nominal value of the air flow rate {dot over (m)}A_NOMand two further contributions. In particular, the nominal value of the air flow rate {dot over (m)}A_NOMrepresents the open-loop contribution and is precisely generated using the experimentally derived control map. The closed-loop contribution {dot over (m)}A_ADAT, is provided by means of a PID controller which tries to zero an error in the air/fuel ratio, namely, a difference between the objective value λOBJof the air/fuel ratio and the actual value λ of the air/fuel ratio measured by the UHEGO or UEGO type linear oxygen sensor18,18*. The third contribution {dot over (m)}A_ADATis also determined depending on the integral action of the PID controller under stationary conditions (i.e., with stationary air flow rate {dot over (m)}A and fuel flow rate {dot over (m)}F). In the case where the sum of the closed-loop contribution αCLand the third contribution αADATis greater than a calibratable threshold value THR2, a breakdown or fault is diagnosed. In the case where the sum of the closed-loop contribution {dot over (m)}A_CLand the third contribution {dot over (m)}A_ADATis greater than a calibratable threshold value THR3, a breakdown or fault is diagnosed. According to a third variant, the pumping device24is regulated by controlling the number N of revolutions while the shut-off valve26is produced with the variable/adjustable passage section (in other words, the shut-off valve26is not of the on/off type). Also in this case, the pressure sensor38is provided in the duct25downstream of the shut-off valve26to detect the pressure PBURNof the air being fed to the burner21. The electronic control unit ECU is therefore designed to determine the objective air flow rate {dot over (m)}A_OBJand the nominal fuel flow rate {dot over (m)}F_Nthat are obtained by operating the pumping device24, the shut-off valve26, the pumping device30and the injector27. According to what is illustrated schematically inFIG.9, the objective air flow rate {dot over (m)}A_OBJis provided at input to a map (typically provided by the manufacturer of the shut-off valve26) together with further quantities that comprise the pressure PAand the temperature TAof the air provided by the sensor33and the pressure PBURNof the air being fed to the burner21provided by the sensor38. The map provides at output the nominal passage section αNOMwith which to operate the shut-off valve26. The actual passage section αOBJwith which to operate the shut-off valve26is, however, defined by the sum of the nominal passage section αNOMand any two further contributions. In particular, the nominal passage section αNOMwith which to operate the shut-off valve26represents the open-loop contribution and is precisely generated using the experimentally derived control map. In the case where the ratio between the pressure PBURNof the air being fed to the burner21and the pressure PAof the air is less than a threshold value THR, the closed-loop contribution αCLis provided by means of a PID controller which tries to zero an error in the air/fuel ratio, namely, a difference between the objective value λOBJof the air/fuel ratio and the actual value λ of the air/fuel ratio measured by the UHEGO or UEGO type linear oxygen sensor18,18*. The third contribution αADATis also determined depending on the integral action of the PID controller under stationary conditions (i.e., with stationary air flow rate {dot over (m)}Aand fuel flow rate {dot over (m)}F). In addition, the objective air flow rate {dot over (m)}A_OBJ is also provided at input to a map (typically provided by the manufacturer of the pumping device24) together with further quantities that comprise the ambient pressure PATMand the ambient temperature TATMprovided by the sensor37and the objective air pressure PA_OBJin the duct25(which is determined depending on the objective air flow rate {dot over (m)}A_OBJand on the pressure PBURNof the air being fed to the burner21). The map provides at output the nominal number NNOMof revolutions with which to operate the pumping device24. The actual number N of revolutions with which to operate the pumping device24is, however, defined by the sum of the nominal number NNOMof revolutions and any three further contributions. In particular, the nominal number NNOMof revolutions with which to operate the pumping device24represents the open-loop contribution and is precisely generated using the experimentally derived control map. The closed-loop contribution NCLis provided by means of a PID1controller which tries to zero an error in the air pressure, namely, a difference between the objective air pressure PA_OBJin the duct25(which is determined depending on the objective air flow rate {dot over (m)}A_OBJand on the pressure PBURNof the air being fed to the burner21) and the actual pressure value PAof the air measured by the sensor33. In addition, in the case where the ratio between the pressure PBURNof the air being fed to the burner21and the pressure PAof the air is greater than a threshold value THR, a further closed-loop contribution NCL2is provided by means of a PID2controller which tries to zero an error in the air/fuel ratio, namely, a difference between the objective value λOBJof the air/fuel ratio and the actual value λ of the air/fuel ratio measured by the UHEGO or UEGO type linear oxygen sensor18,18*. The third contribution NADATis also determined depending on the sum of the integral action of the PID1controller and of the PID2controller under stationary conditions (i.e., with stationary air flow rate {dot over (m)}Aand fuel flow rate {dot over (m)}F). In other words, regulation of the air flow rate {dot over (m)}Ais controlled depending on the ratio between the pressure PBURNof the air being fed to the burner21(downstream of the shut-off valve26) and on the pressure PAof the air (upstream of the shut-off valve26). When the said ratio is less than the threshold value THR, to control the air flow rate {dot over (m)}A, the opening of the shut-off valve26is operated; since said ratio is greater than the threshold value THR, to control the air flow rate {dot over (m)}A, the pumping device24is operated and the shut-off valve26is substantially fully open. According to what is illustrated inFIG.10, in the case where the ratio between the pressure PBURNof the air being fed to the burner21and the pressure PAof the air in the duct25is greater than the threshold value THR, the third contribution NADATwith which to operate the pumping device24is used to update the map used previously to determine the nominal number NNOMof revolutions. In particular, the third contribution NADATis provided at input to the map together with further quantities that comprise the ambient pressure PATMand the ambient temperature TATMprovided by the sensor37and the pressure PAof the air in the duct25provided by the sensor33. The map provides at output the updated value of the air flow rate {dot over (m)}A_RPH. On the other hand, in the case where the ratio between the pressure PBURNof the air being fed to the burner21and the pressure PAof the air in the duct25is less than the threshold value THR, the third contribution αADATwith which to operate the shut-off valve26is used to update the map used previously to determine the nominal passage section αNOMwith which to operate the shut-off valve26. In particular, the third contribution αADATis provided at input to the map together with further quantities that comprise the pressure PBURNof the air being fed to the burner21, the pressure PAand the temperature TAof the air in the duct25. The map provides at output the updated value of the air flow rate {dot over (m)}A_RPL. In the case where the sum of the closed-loop contribution NCLand the third contribution NADATis greater than a calibratable threshold value THR1, a breakdown or fault is diagnosed. In the case where the sum of the closed-loop contribution αCLand the third contribution αADATis greater than a calibratable threshold value THR2, a breakdown or fault is diagnosed. According to a fourth variant schematically illustrated inFIG.13, the pumping device24is regulated by controlling the number N of revolutions while the shut-off valve26is of the on/off type. The electronic control unit ECU is designed to determine the objective air flow rate {dot over (m)}A_OBJand the nominal fuel flow rate {dot over (m)}F_Nthat are obtained by operating the pumping device24, the pumping device30and the injector27. According to what is illustrated schematically inFIG.11, the objective air flow rate {dot over (m)}A_OBJis also provided at input to a map (typically provided by the manufacturer of the pumping device24) together with further quantities that comprise the ambient pressure PATMand the ambient temperature TATMprovided by the sensor37and the pressure PAof the air in the duct25provided by the sensor33. The map provides at output the nominal number NNOMof revolutions with which to operate the pumping device24. The actual number N of revolutions with which to operate the pumping device24is, however, defined by the sum of the nominal number NNOMof revolutions and two further contributions. In particular, the nominal number NNOMof revolutions with which to operate the pumping device24represents the open-loop contribution and is precisely generated using the experimentally derived control map; while the closed-loop contribution NCLis provided by means of a PID controller which tries to zero an error in the air flow rate, namely, a difference between the objective air flow rate {dot over (m)}A_OBJand the air flow rate {dot over (m)}A. In addition, according to what is illustrated inFIG.13, the air flow rate {dot over (m)}Ais calculated by subtracting the total air flow rate {dot over (m)}TOTdetected by the mass air flow sensor9from the air flow rate {dot over (m)}ICEfed to the internal combustion engine1. The air flow rate {dot over (m)}ICEfed to the internal combustion engine1is determined, for example, by the method to determine the mass of air trapped in each cylinder of an internal combustion engine described in the patent applications EP3650678 and EP3739192A, which are incorporated herein for reference. The third contribution NADATis also determined depending on the integral action of the PID controller under stationary conditions (i.e., with stationary air flow rate {dot over (m)}Aand fuel flow rate {dot over (m)}F). According to what is illustrated inFIG.12, the third contribution NADATwith which to operate the pumping device24is then used to update the map used previously to determine the nominal number NNOMof revolutions. In particular, the difference between the actual number N of revolutions with which to operate the pumping device24and the third contribution NADATis provided at input to the map together with further quantities that comprise the ambient pressure PATMand the ambient temperature TATMprovided by the sensor37and the pressure PAof the air in the duct25provided by the sensor33. The map provides at output the updated value of the air flow rate {dot over (m)}A. In the case where the sum of the closed-loop contribution NCLand the third contribution NADATis greater than a calibratable threshold value THR1, a breakdown or fault is diagnosed. According to a fifth and final variant illustrated schematically inFIG.14, the pumping device24is regulated by controlling the number N of revolutions while the shut-off valve26is of the on/off type. A mass air flow sensor39(better known as Air Flow Meter) is also arranged along the duct25, interposed between the pumping device24and the shut-off valve26. According to a further embodiment (not illustrated), the mass air flow sensor is arranged along the duct25upstream of the pumping device24. The electronic control unit ECU is therefore designed to determine the objective air flow rate {dot over (m)}A_OBJand the nominal fuel flow rate {dot over (m)}F_Nthat are obtained by operating the pumping device24, the pumping device30and the injector27. According to what is illustrated schematically inFIG.11, the objective air flow rate {dot over (m)}A_OBJis also provided at input to a map (typically provided by the manufacturer of the pumping device24) together with further quantities that comprise the ambient pressure PATMand the ambient temperature TATMprovided by the sensor37and the pressure PAof the air in the duct25provided by the sensor33. The map provides at output the nominal number NNOMof revolutions with which to operate the pumping device24. The actual number N of revolutions with which to operate the pumping device24is, however, defined by the sum of the nominal number NNOMof revolutions and two further contributions. In particular, the nominal number NNOMof revolutions with which to operate the pumping device24represents the open-loop contribution and is precisely generated using the experimentally derived control map; while the closed-loop contribution NCLis provided by means of a PID controller which tries to zero an error in the air flow rate, namely, a difference between the objective air flow rate {dot over (m)}A_OBJand the air flow rate {dot over (m)}Adetected by the mass air flow sensor39. The third contribution NADATis also determined depending on the integral action of the PID controller under stationary conditions (i.e., with stationary air flow rate {dot over (m)}Aand fuel flow rate {dot over (m)}F). According to what is illustrated inFIG.12, the third contribution NADATwith which to operate the pumping device24is then used to update the map used previously to determine the nominal number NNOMof revolutions. In particular, the third contribution NADATis provided at input to the map together with further quantities that comprise the ambient pressure PATMand the ambient temperature TATMprovided by the sensor37and the pressure PAof the air in the duct25provided by the sensor33. The map provides at output the updated value of the air flow rate {dot over (m)}A. In the case where the sum of the closed-loop contribution NCLand the third contribution NADATis greater than a calibratable threshold value THR1, a breakdown or fault is diagnosed. According to what is schematically illustrated inFIG.5, once the electronic control unit ECU has determined the actual number N of revolutions with which to operate the pumping device24to obtain the objective air flow rate {dot over (m)}A_OBJ, the nominal fuel flow rate {dot over (m)}F_Nis calculated. The nominal fuel flow rate {dot over (m)}F_Nis determined by the following formula: m.FUEL-N=m.A(AFSTEC*λOBJ) {dot over (m)}FUEL-Nnominal fuel flow rate {dot over (m)}Aestimated air flow rate A/FSTECstoichiometric air and fuel ratio λOBJdesired/objective value of the air/fuel ratio. The estimated air flow rate {dot over (m)}Ais determined according to the method illustrated inFIG.6and described in the preceding disclosure. The objective fuel flow rate {dot over (m)}F_OBJis, however, defined by the sum of the nominal fuel flow rate {dot over (m)}FNand two further contributions. In particular, the nominal fuel flow rate {dot over (m)}F_Nrepresents the open-loop contribution and is precisely generated using the formula described previously; while the closed-loop contribution of the fuel flow rate is provided by a PID controller which tries to zero an error in the air/fuel ratio, namely, a difference between the objective value λOBJof the air/fuel ratio and the actual value λ of the air/fuel ratio measured by the UHEGO or UEGO type linear oxygen sensor18,18*. The third contribution {dot over (m)}F_ADATof the fuel flow rate is also determined depending on the integral action of the PID controller under stationary conditions (i.e., with stationary air flow rate {dot over (m)}Aand fuel flow rate {dot over (m)}F). In the case where the sum of the closed-loop contribution {dot over (m)}F_CLand the third contribution {dot over (m)}F_ADATis greater than a calibratable threshold value THR4, a breakdown or fault is diagnosed. In the case of a fault of the mass air flow sensor9or39, the air flow rate {dot over (m)}Ais calculated by means of a map depending on the ambient pressure PATM, on the ambient temperature TATMand on the pressure PAof the air entering the burner21, the actual number N of revolutions with which to operate the pumping device24, and the further adaptive contribution NADATof the number of revolutions with which to operate the pumping device24. It is clear that the strategies described in the previous disclosure to control and adapt the objective fuel flow rate {dot over (m)}F_OBJand the air flow rate {dot over (m)}Amay be used with any layout of the exhaust system2(regardless of the position of the linear oxygen sensor18,18*). It is also clear that the previous disclosure may also find advantageous application in the case where the linear oxygen sensor18,18*,18** is replaced by a lambda sensor suited to provide a binary on/off type output (indicating whether the exhaust gases titer is above or below the stoichiometric value). In particular, the strategies described in the previous disclosure may also find advantageous application in the case of a linear oxygen sensor18** housed along the outlet duct35. LIST OF REFERENCE NUMBERS 1internal combustion engine2exhaust system3cylinders4intake manifold5exhaust manifold6intake duct7air filter8throttle valve9mass air flow sensor10exhaust duct11turbocompressor12turbine13compressor14after-treatment system15precatalytic converter16particulate filter17catalytic converter18UEHO linear sensor or HEGO switching19lambda sensor20lambda sensor21burner22combustion chamber23air feeding circuit24pumping device25duct26shut-off valve27injector28spark plug29fuel feeding circuit30pumping device31duct32control system33sensor P, T34sensor P, T35outlet duct *36sensor P, T37sensor P, T38pressure sensor39mass air flow sensor | 39,363 |
11859528 | DETAILED DESCRIPTION OF THE INVENTION The present invention concerns a method for controlling an exhaust gas aftertreatment system in order to reduce tailpipe NOx emissions below levels reliably detectable by current NOx sensors. The invention is based upon a realization by the inventors that the non-selectivity of NOx sensors could be exploited to ensure that a suitable level of over-dosing of ammonia is provided using feedback control, thus allowing tailpipe NOx emission levels to be obtained that are below the levels detectable by current NOx sensors. This is feasible as long as it is possible to determine whether a NOx sensor located downstream of the SCR catalyst is operating in a NOx-rich environment (sub-stoichiometric dosing of ammonia to SCR) or an ammonia-rich environment (over-stoichiometric dosing of ammonia to SCR). A tailpipe NOx sensor arranged downstream of the ammonia slip catalyst enables such a determination in combination with a feedback NOx sensor arranged downstream of the SCR device and upstream of the ammonia slip catalyst. The exhaust gas aftertreatment system comprises a reductant dosing device, a selective catalytic reduction (SCR) device, an ammonia slip catalyst and a plurality of NOx sensors. The relation of aftertreatment system components to each other will in this application be defined in terms of upstream and downstream. Upstream and downstream respectively refer to positions in the exhaust aftertreatment system with reference to the typical direction of flow of exhaust gas from the engine to the tailpipe. A component is designated upstream of another if it is located in the exhaust system closer to the engine, whereas it is designated downstream if it is located in the exhaust system closer to the tailpipe. The reductant dosing device is arranged to dose reductant to the exhaust gas aftertreatment system. To this end, the reductant dosing device may comprise or consist of at least one reductant injector. The reductant injector may be of any type known in the art, such as an air-assisted (e.g. jetspray) injector, or a liquid-only (i.e. airless) injector. The reductant may be any SCR reductant known in the art. The reductant is preferably diesel exhaust fluid comprising a solution of urea in water, in accordance with standard AUS 32 of ISO 22241, due to its widespread commercial availability and easy handling. However, other reductants such as aqueous ammonia solution or guanidinium salt solutions may also be used where appropriate. The SCR device is arranged downstream of the reductant dosing device. The SCR device may be of any type known in the art. By SCR device, it is meant a device comprising a catalyst capable of catalysing the reduction of NOx to N2using the reductant. The SCR catalyst device may be a dedicated SCR catalyst, or it may be a device combining the function of an SCR catalyst with another function. For example, the SCR device may be an SCR-catalysed diesel particulate filter (SDPF). The SCR device may comprise multiple SCR catalysts arranged in parallel or series. Selective catalytic reduction (SCR) is used to convert nitrogen oxides (NOx) to benign nitrogen gas (N2), typically using ammonia as the reductant. The dominant reactions in ammonia SCR are: 4 NH3+4 NO+O2→4 N2+6 H2O 4 NH3+2 NO2+2 NO→4 N2+6 H2O It can be seen from these reactions that the optimal stoichiometry of NH3to NOx is approximately 1:1, i.e. an ammonia:NOx ratio (ANR) of about approximately 1. Therefore, an ANR greater than stoichiometric (over-stoichiometric) may be about 1.1 or greater, such as about 1.2 or about 1.3. An ANR less than stoichiometric (sub-stoichiometric) may be less than or equal to 1, such as less than or equal to 0.9. Sub-stoichiometric dosing of ammonia leads to incomplete conversion of NOx, i.e. NOx detectable at the outlet of the SCR device, whereas over-dosing of ammonia leads to ammonia slip, i.e. unreacted ammonia detectable at the outlet of the SCR device. An ammonia slip catalyst is arranged downstream of the SCR device. Ammonia slip catalysts prevent tailpipe ammonia emissions by oxidation of excess ammonia to benign nitrogen gas (N2). However, this catalytic reaction is not fully selective and a proportion of ammonia slip is unavoidably converted to N2O in the catalyst. N2O is a strong greenhouse gas and its emission is highly undesirable. Therefore it is desired to limit the over-stoichiometric dosing of ammonia to a level whereby substantially all NOx is converted but no more, in order to limit production of N2O. Appropriate ANR values may for example be from about 1.05 to about 1.3, such as from about 1.1 to about 1.2. When using over-stoichiometric ammonia:NOx ratios it is advantageous if the ammonia slip catalyst also possesses SCR functionality, since in this manner it may assist in further reducing NOx emission levels or permit use of a smaller-dimensioned SCR catalyst. The exhaust aftertreatment system comprises at least two NOx sensors, preferably three or more NOx sensors. The NOx sensors may be any type known in the art, such as the commercially available YSZ-type NOx sensors. Commercially available NOx sensors are typically not fully selective for NOX and also detect ammonia (NH3). A NOx sensor is arranged in the exhaust aftertreatment system downstream of the ammonia slip catalyst, and is herein termed the tailpipe NOx sensor. Note however that this sensor may be located anywhere in the aftertreatment system downstream of the ASC and is not necessarily located in a tailpipe of the exhaust system. A further NOx sensor is arranged between the SCR and the ASC, downstream of the SCR and upstream of the ASC. This NOx sensor is herein termed the feedback sensor since feedback from this sensor is used to achieve ANR values within a desired interval. Optionally, a NOx sensor may be arranged upstream of the reductant dosing device. This sensor is herein termed the initial NOx sensor and may be used in conjunction with exhaust flow data (either virtual or measured by flow sensor) in order to determine a suitable initial dosing rate of reductant. The exhaust aftertreatment system may comprise further components as commonly known in the art. For example, a diesel oxidation catalyst (DOC) and/or diesel particulate filter (DPF), or combined DOC/DPF may be arranged upstream of the reductant distribution arrangement. A pre-SCR unit comprising a reductant dosing device and SCR catalyst may be arranged upstream of the DOC in order to remove a proportion of exhaust NOx prior to the exhaust gas reaching the main SCR device as described herein. A mixer or evaporation plate may be arranged in conjunction with the reductant dosing device in order to improve the distribution of reductant in the exhaust stream. Further sensors, such as temperature sensors, flow sensors, and/or pressure sensors may be arranged as suitable in the aftertreatment system. The exhaust aftertreatment system may comprise a control device configured to perform the method as described herein. Alternatively, or in addition, the exhaust aftertreatment system may in use be arranged in communication with another suitable control device for performing the method described herein. The inventive method will now be described in more detail with reference to certain exemplifying embodiments and the drawings. However, the invention is not limited to the exemplifying embodiments discussed herein and/or shown in the drawings, but may be varied within the scope of the appended claims. Furthermore, the drawings shall not be considered drawn to scale as some features may be exaggerated in order to more clearly illustrate certain features. FIG.1depicts a vehicle1, here in the form of a truck, in a schematic side view. The vehicle may however be any other motor driven vehicle, for example a bus, a watercraft, or a passenger car. The vehicle comprises a combustion engine2which powers the vehicle's tractive wheels3via a gearbox (not shown) and a drive shaft (not shown). The vehicle is provided with an exhaust gas aftertreatment system4for treating exhaust gases expelled by the engine2. FIG.2schematically illustrates an exhaust aftertreatment system4as known in the prior art. An arrow11indicates the direction of exhaust flow. The terms “downstream” and “upstream” are used with reference to the direction of exhaust flow as indicated by arrow11. The system comprises an initial NOx sensor13. The initial NOx sensor is connected to a control device15. Downstream of the initial NOx sensor13a diesel oxidation catalyst (DOC)17and diesel particulate filter (DPF)19are arranged in series. Downstream of the DOC17and DPF19, a dosing device23is arranged to introduce urea into the aftertreatment system. A temperature sensor21is arranged downstream of the DPF19and upstream the dosing device23. The dosing device23is connected to control device15. Downstream of the dosing device23an SCR device27is arranged, and immediately downstream of the SCR device27an ammonia slip catalyst (ASC)29is arranged. A tailpipe NOx sensor31is arranged downstream of the ASC29and is connected to control device15. In operation, urea solution is dosed to the prior art exhaust aftertreatment system with the aim of achieving as uniform distribution of reductant as possible at the SCR device27. An exhaust gas temperature of approximately at least 150° C. (e.g. about at least 180° C. or about at least 200° C.) is required to be able to evaporate the dosed urea and produce NH3. The exhaust gas temperature may be measured using temperature sensor21. Dosing is controlled by the control device15, based on the signal from NOx sensors13,31, together with other inputs such as for example exhaust gas temperature and/or exhaust flow (measured or calculated). The urea decomposes to ammonia and is conveyed to the SCR device27. The SCR device27catalyses the reaction of the ammonia with NOx present in the exhaust stream. At the outlet of the SCR device27a relatively uniform exhaust stream comprising a mixture of NOx and some ammonia slip is obtained. This exhaust stream is conveyed further to the ASC29where some further NOx may be removed by SCR and the remaining ammonia is oxidized to nitrogen. The exhaust stream exiting the ASC29comprises residual NOx and essentially no ammonia. Initial dosing of reductant is determined by the NOx concentration measured at the initial NOx sensor13together with exhaust flow data (either virtual or from a flow sensor). Due to limits in the measuring accuracy of NOx and exhaust flow, as well as variation in the dosing accuracy from dosing device23, and variation in ambient conditions (ambient temperature, pressure and humidity), the initial dosing typically falls within the range of from about 0.8 to about 1.2 ANR. The tailpipe NOx sensor31detects residual NOx levels and is used in feedback control of urea dosing from dosing device23in order to obtain an ANR suitable for near-complete removal of NOx (typically from about 1.05 to about 1.1). Such prior art arrangements work satisfactorily as long as the residual NOx level is permitted to be above the limit reliably measurable by the tailpipe NOx sensor31, which is approximately 0.1 g/kWh. However, if the permitted NOx emission is below the limit that may reliably be measurable by the tailpipe NOx sensor31, the tailpipe sensor31cannot be used to control dosing of urea from dosing device23. FIG.3schematically illustrates an exemplifying embodiment of an exhaust gas aftertreatment system4according to the present invention. The exhaust gas aftertreatment system resembles the prior art system as illustrated inFIG.2, however with an important difference. A feedback NOx sensor33is arranged downstream of the SCR device27and upstream of the ASC29. This feedback NOx sensor33permits feedback control of reductant dosing when used in combination with data from the tailpipe sensor31. FIG.4is a chart schematically illustrating NOx concentration (line431) and ammonia concentration (line435) as a function of ammonia:NOx ratio (ANR) at the outlet of an SCR device. The concentrations are given in ppm and were obtained under steady-state operating conditions at 300° C. The chart also shows the reading obtained from a NOx sensor arranged at the outlet of the SCR device (line433), which is equivalent to the feedback NOx sensor33in the exhaust aftertreatment system according to the invention. The chart illustrated inFIG.4can be used to understand the operation principles of the exhaust aftertreatment system. At low ANR values (<0.95) it can be seen that significant quantities of NOx escape the SCR device (line431), but there is essentially no ammonia slip (line435). At these ANR values, the reading from the feedback NOx sensor (line433) therefore essentially corresponds to the NOx concentration at the SCR device outlet. At high ANR values (ANR>1.05) it can be seen that essentially no NOx escapes the SCR device (line431), but that significant quantities of ammonia slip are produced (line435). As previously stated, NOx sensors are non-selective, meaning that they cannot distinguish between NOx and ammonia slip. At high ANR values, the reading from the feedback NOx sensor (line433) therefore essentially corresponds to the ammonia slip concentration at the SCR device outlet. In a transitional ANR range (between approx. ANR 0.95-1.05) there is incomplete reaction of ammonia with NOx, meaning that both NOX emission (line431) and ammonia slip (line435) are detected at the SCR device outlet. In such a transitional case, the feedback NOx sensor measures the combined concentration of NOx and ammonia (line433). It can be seen from the chart inFIG.4that the feedback NOx sensor33cannot alone be used to control reductant dosing in order to achieve a desirable ammonia:NOx ratio (ANR). This is because the feedback NOx sensor output signal curve (line433) on sweeping from low ANR values to high ANR values is essentially a symmetrical U-shape, with a minimum around ANR of approximately 1. This means that the feedback NOx sensor gives more-or-less the same output for a low ANR value as for a high ANR value (compare for instance ANR 0.8 with ANR 1.2). Note also that in real-life operation exhaust parameters such as temperature, flow and NOx concentration fluctuate, meaning that the gradient of the feedback sensor curve cannot be measured and used to determine whether the aftertreatment system is operating in the low-ANR or the high-ANR regime. Line451illustrates a typical detection limit for an automotive NOx sensor, and it can be seen that at high ANR values the NOx concentration is lower than the concentration measurable with an automotive NOx sensor. This means that it is not possible to control ANR at high ANR values using only a tailpipe NOx sensor. The solution to this problem is to use a feedback NOx sensor33in combination with a tailpipe NOx sensor31in order to establish whether the exhaust aftertreatment system is operating in a low-ANR regime or a high-ANR regime and provide feedback control of the reductant dosing in order to steer ANR to the desired interval of values (ANR 1.05-1.3, preferably 1.1-1.2). Since tailpipe sensor31is arranged downstream of the ASC29, it is not subjected to ammonia slip, and therefore the signal from tailpipe sensor31essentially corresponds to the NOx curve as illustrated in line431ofFIG.4. From the chart inFIG.4it can be seen that there are a number of ways in which the signals from feedback NOx sensor433and tailpipe NOx sensor431may be used to control ammonia dosing in order to achieve an ANR within the desired interval. All of these ways have in common that the dosing of reductant is adjusted in some manner until the feedback signal exceeds the tailpipe NOx signal by a value within a predetermined positive interval. For example, it may be desirable to adjust dosing such that the feedback signal exceeds the tailpipe NOx signal by a value within an interval corresponding to from about 0.2 to about 0.5 g/kWh (about 20-50 ppm) of ammonia. Controlling dosing to provide such an excess of ammonia will lead to NOx emissions lower than 0.05 g/kWh, as well as very low N2O emissions. The first manner in which this may be done is through a simple comparison of the signals of the feedback NOx sensor31and the tailpipe NOx sensor33. It can be seen fromFIG.4that at low ANR values the difference between the signals from these sensors is negligible (Δkw), since both sensors are measuring the same NOx emission, whereas at high ANR values the difference in the sensor signal is large (Δhigh), since feedback NOx sensor33is detecting significant amounts of ammonia slip, whereas tailpipe NOx sensor is arranged downstream of the ASC29and therefore does not detect this slip. Therefore, a first means of controlling the ammonia dosing is by determining the difference in signal output between feedback NOx sensor31and tailpipe NOx sensor33(Δ). If this difference is less than a lower boundary for the difference then ammonia dosing should be increased (e.g. if Δ<30 ppm then increase ammonia dosing), whereas if it is greater than an upper boundary for the difference then ammonia dosing should be decreased (e.g. if Δ>100 ppm then decrease ammonia dosing). FIG.5is a flowchart illustrating an exemplifying embodiment of this first method of controlling the exhaust gas aftertreatment system. Step s501denotes the start of the method. In step s503an initial dosing of reductant is dosed from the reductant dosing device23. This initial dosing may be based on a signal from the initial NOx sensor13, or may be determined in some other manner. In step s505a feedback signal is obtained from the feedback NOx sensor31and a tailpipe NOx signal is obtained from the tailpipe NOx sensor33. In step s507the difference (Δ) is determined between the feedback signal and the tailpipe NOx signal. In step s509the determined difference (Δ) is compared with a lower boundary difference value and an upper boundary difference value. If the determined difference is lower than the lower boundary value then dosing is increased (s511) and the method returns again to step s505of obtaining the tailpipe and feedback signals. If the determined difference is higher than the upper boundary value then dosing is decreased (s513) and the method returns again to step s505of obtaining the tailpipe and feedback signals. If the determined difference is within the boundary values then the initial dosing is maintained and the method returns directly to step s505of obtaining the tailpipe and feedback signals. A second manner in which the exhaust aftertreatment system may be controlled is by first establishing that the tailpipe NOx sensor31has a signal lower than a threshold value. The threshold value may for example be the detection limit of the sensor (e.g. line451inFIG.4), or at least a value in proximity to the detection limit of the sensor (e.g. 5% to 10% above the detection limit). If the signal of the tailpipe NOx sensor exceeds this threshold value, ammonia dosing should be increased until the signal of the tailpipe NOx sensor is less than this threshold. Once this condition is fulfilled, it is established that the exhaust aftertreatment system is operating in the high-ANR region, and the ammonia dosing may be controlled using the feedback signal from feedback NOx sensor31to steer the ANR to the desired interval. If the feedback signal is below a lower boundary value (e.g. 30 ppm) then the dosing of reductant is increased, or if the feedback signal is above an upper boundary value (e.g. 100 ppm) then the dosing of reductant is decreased. The lower boundary value for the feedback signal should be at least equal to or greater than the threshold value for the tailpipe NOx signal. FIG.6is a flowchart illustrating an exemplifying embodiment of this second method of controlling the exhaust gas aftertreatment system. Step s601denotes the start of the method. In step s603an initial dosing of reductant is dosed from the reductant dosing device23. This initial dosing may be based on a signal from the initial NOx sensor13, or may be determined in some other manner. In step s605a feedback signal is obtained from the feedback NOx sensor33and a tailpipe NOx signal is obtained from the tailpipe NOx sensor31. In step s607the tailpipe NOx signal is compared with a threshold tailpipe NOx value. If the tailpipe NOx signal is greater than a threshold tailpipe NOx value then the dosing of reductant is increased (s611) and the method returns again to step s605of obtaining the tailpipe and feedback signals. If the tailpipe NOx signal is less than the threshold tailpipe NOx value then the method proceeds to step s609. In step s609the feedback signal is compared with a lower boundary value and an upper boundary value. If the feedback signal is below the lower boundary value then the dosing of reductant is increased (s611) and the method returns again to step s605of obtaining the tailpipe and feedback signals. If the feedback signal is above the upper boundary value then the dosing of reductant is decreased (s613) and the method returns again to step s605of obtaining the tailpipe and feedback signals. If the feedback signal is within the boundary values then the initial dosing is maintained and the method returns directly to step s605of obtaining the tailpipe and feedback signals. It is noted that during operation within the desired ANR interval, the feedback NOx sensor33is primarily measuring ammonia slip, and not NOx emission. Therefore, the feedback NOx sensor could in theory be replaced by an ammonium sensor. However, since ammonium sensors are expensive, less robust than NOx sensors, and have the same issues with regard to non-selectivity, it is preferred that a feedback NOx sensor is utilized. During operation, the temperature of the exhaust aftertreatment system may fluctuate. The SCR catalyst is capable of storing an amount of ammonia, and this storage capacity is a function of temperature. During temperature transients, the amount of ammonia stored in the SCR catalyst may rapidly increase or decrease, leading to a transient deficit or peak of ammonia slip at the feedback NOx sensor31. In order to account for such effects the signals from the NOx sensors, such as the signals from the feedback NOx sensor33and tailpipe NOx sensor31, may be time-averaged. For example, the signals may be averaged over a period of from about 1 minute to about 20 minutes. | 22,534 |
11859529 | DESCRIPTION OF EMBODIMENT(S) An exhaust purification device as an embodiment will now be described with reference to the drawings. The embodiment described below is merely an example and there is no intention to exclude application of various modifications and techniques not specified in the following embodiment. Each configuration of the present embodiment can be variously modified and implemented without departing from the gist thereof. In addition, it can be selected as needed or can be combined as appropriate. [1. Overall Configuration] An exhaust purification device1of the present embodiment is a device that purifies exhaust gas discharged from an engine (for example, a diesel engine, not illustrated) mounted on a vehicle. The present embodiment exemplarily discloses, as illustrated inFIG.1, the exhaust purification device1including a DPF device2and an SCR device3. Further, the present embodiment exemplarily discloses a configuration in which the exhaust purification device1is attached to a side frame10(partially indicated by two-dot chain lines inFIG.1). The side frame10is a frame member provided in a pair of left and right and extending in a vehicle front-rear direction, and is, for example, formed to have a U-shaped cross section. The outlined arrow inFIG.1indicates flow of the exhaust gas that flows into the DPF device2. The DPF device2is a purification device arranged on an upstream side in the exhaust purification device1, and is configured by accommodating an upstream oxidation catalyst and a particulate filter (Diesel Particulate Filter, hereinafter referred to as “DPF”), each of which is not illustrated, in a first casing2C formed into a cylinder. The upstream oxidation catalyst is an oxidation catalyst that oxidizes nitric oxide (NO) contained in the exhaust gas, hydrocarbons (HC) contained in unburned fuel, etc., and is configured by a catalytic substance supported by a honeycomb-shaped carrier. The DPF is a porous filter that collects particulate matter (Particulate Matter, hereinafter referred to as “PM”) contained in the exhaust gas, and is arranged downstream of the upstream oxidation catalyst. The upstream oxidation catalyst and the DPF are purifiers for exhaust purification. The SCR device3is a purification device arranged on a downstream side in the exhaust purification device1, and is configured by accommodating a catalyst3A for selective catalytic reduction (seeFIG.3, Selective Catalytic Reduction, hereinafter referred to as “SCR3A”) and a downstream oxidation catalyst3B (seeFIG.3) in a second casing3C formed in a cylinder. The SCR3A is a catalyst that reduces and removes nitrogen oxides (NOx) contained in the exhaust gas, and is configured by a catalyst supported by a honeycomb-shaped carrier. The SCR3A hydrolyzes additive (urea water) supplied from a reducing agent injector6provided on the upstream side of the SCR device3to ammonia (NH3), adsorbs the ammonia, and reduces the NOx in the exhaust gas to nitrogen (N2) by using the adsorbed ammonia as the reducing agent. The downstream oxidation catalyst3B is an oxidation catalyst arranged downstream of the SCR3A to remove excess ammonia in the reduction reaction in the SCR3A, and is configured, for example, to be similar to the upstream oxidation catalyst. The SCR3A and the downstream oxidation catalyst3B are also purifiers for exhaust purification. Longitudinal directions of the casings2C and3C both coincide with the flow direction of the exhaust gas. The exhaust purification device1of the present embodiment is mounted on the vehicle, in an orientation such that the longitudinal direction of the second casing3C crosses the longitudinal direction of the first casing2C at substantially right angles. More specifically, the first casing2C is mounted in an orientation such that the longitudinal direction thereof substantially coincides with the vehicle front-rear direction, and the second casing3C is mounted in an orientation such that the longitudinal direction thereof substantially coincides with a vehicle width direction. The first casing2C is provided with an inlet opening (not illustrated) to allow the exhaust gas to flow into the first casing2C at a first longitudinal end (the end on a vehicle front side), and is also provided with an outlet opening (not illustrated) to allow the exhaust gas to flow out of the first casing2C at a second longitudinal end (the end on a vehicle rear side). To the inlet opening of the first casing2C, a pipe (not illustrated) that joins the engine to the DPF device2is connected. At least one of the pipe and an upstream end of the first casing2C is fixed to the side frame10via a non-illustrated bracket or the like. The second casing3C is provided with an inlet opening3d(seeFIG.3) to allow the exhaust gas to flow into the second casing3C at a first longitudinal end (the end on a vehicle right side), and is also provided with an outlet opening3e(seeFIG.3) to allow the exhaust gas to flow out of the second casing3C at a second longitudinal end (the end on a vehicle left side). In each ofFIGS.3and5, the flow direction of the exhaust gas is indicated by an outlined arrow. The exhaust purification device1is provided with two types of pipes4and5. A first pipe4communicates the two casings2C and3C with each other, and constitutes a flow path that guides the exhaust gas which has flowed through the first casing2C to the second casing3C. Namely, an upstream end of the first pipe4is connected to the outlet opening of the first casing2C, and a downstream end of the first pipe4is connected to the inlet opening3dof the second casing3C. The first pipe4of the present embodiment forms one pipe by two pipe members connected to each other via flanges4fin a portion extending in the vehicle width direction. However, the first pipe4may be configured by a single pipe instead of being the split type. As illustrated inFIGS.2and5, a second pipe5has an upstream end thereof connected to the outlet opening3eof the second casing3C, and constitutes a flow path that discharges the exhaust gas purified by the exhaust purification device1to the outside of the vehicle. As in the case of the first pipe4, the second pipe5of the present embodiment also forms one pipe by two pipe members connected via flanges5fin a portion extending in the vehicle width direction. However, the second pipe5may be configured by a single pipe instead of being the split type. In the exhaust purification device1of the present embodiment, the first pipe4extends in the vehicle width direction and the reducing agent injector6described above is provided on the first pipe4. The position of the reducing agent injector6is not limited to this, and may be, for example, a connection point between the first casing2C and the first pipe4, or in the first casing2C if the upstream end of the first pipe4is placed in the first casing2C. The exhaust purification device1of the present embodiment has an attachment member20that attaches the two casings2C and3C to a vehicle body (the side frame10in the present embodiment), in a state where the first casing2C and the second casing3C are connected to each other. The attachment member20includes a DPF band21that holds an outer periphery of the first casing2C, two SCR bands22that each hold an outer periphery of the second casing3C, two side face portions23that sandwich the second casing3C from the vehicle front-rear direction, and a connecting face portion24that connects the DPF band21to the side face portions23. The DPF band21holds a vehicle rear side portion of the first casing2C, and is fastened to the connecting face portion24. Each of the SCR bands22holds the second casing3C at a different position in the longitudinal direction, and is fastened to the side face portions23. The side face portions23are fastened to the connecting face portion24. As such, in the exhaust purification device1of the present embodiment, the DPF device2and the SCR device3are mounted on the vehicle in a compact state. The exhaust purification device1includes multiple sensors7provided on at least each of the first casing2C and the second casing3C to detect the condition of the exhaust gas flowing inside, and multiple controllers8that control each of the multiple sensors7. Examples of the sensors7include a temperature sensor, a pressure sensor, a NOx sensor, a PM sensor, and an NH3sensor. The sensor designated by reference numeral7A inFIG.1is a temperature sensor, and the sensor designated by the reference symbol7B is a NOx sensor or an NH3sensor. The various types of sensors7may be arranged on, in addition to the casings2C and3C, the pipe on the upstream side of the first casing2C, the first pipe4, and/or the second pipe5. The controllers8are provided one for each sensor7and are connected to the corresponding sensors7via harnesses9. Examples of the controllers8include a pressure sensor controller, a temperature sensor controller, a NOx sensor controller, a PM sensor controller, and an NH3sensor controller. The harnesses9are arranged along the peripheries of the first casing2C and the second casing3C, and are prevented from displacement by non-illustrated clips or the likes. In the exhaust purification device1of the present embodiment, the multiple controllers8are attached to a bracket11so as to be integrally arranged at one place, but alternatively, each of the controllers8may be arranged at the position of the corresponding sensor7to omit the bracket11. [2. Main Configuration] Next, description will be made in relation to the structure of the two pipes4and5connected to the second casing3C (hereinafter, simply referred to as “casing3C”) of the exhaust purification device1, and the connection structure of each of the pipes4and5to the casing3C.FIG.2is a side view illustrating a state in which each of the pipes4and5is connected to the casing3C, andFIGS.3to5are cross-sectional views as seen from the arrows X-X, Y-Y, and Z-Z ofFIG.2, respectively. These figures illustrate each of the pipes4and5separated at each of the flanges4fand5f. As illustrated inFIGS.1and3, the first pipe4is formed in a substantially L-shape when viewed from the vehicle rear side (in a rear view). The first pipe4of the present embodiment includes a body4aextending in the vehicle width direction, a corner4ccurving upward from an end on the vehicle outer side of the body4a, and a connecting end4bconnected to the casing3C. The body4a, the corner4c, and the connecting end4bare continuous, and an extending direction of the body4ais orthogonal to an extending direction of the connecting end4b. In the present embodiment, the extending direction of the body4acoincides with the longitudinal direction (vehicle width direction) of the casing3C, and the extending direction of the connecting end4bcoincides with a lateral direction (if the casing3C is a cylinder, a radial direction) of the casing3C. As illustrated inFIG.2, a cross section of the body4aof the present embodiment is substantially circular, and is uniform in a longitudinal direction (i.e., the vehicle width direction) of the body4a. Hereinafter, an outer diameter of the cross section of the body4ais defined as L1. As illustrated inFIG.3, the cross section of the first pipe4changes from the body4ato the connecting end4bvia the corner portion4c. Specifically, while the cross section of the body4ais substantially circular, as illustrated inFIG.4, a cross section of the connecting end4bis in a flattened shape as if the cross section of the body4ais crushed (narrowed). As illustrated inFIGS.3and4, the cross section of the connecting end4bis in the flattened shape as a dimension (longitudinal dimension L1′) along the longitudinal direction of the casing3C is shorter than a dimension (lateral dimension) along the lateral direction of the casing3C. AlthoughFIG.4illustrates the first pipe4in which the lateral dimension of the cross section of the connecting end4bis equal to the outer diameter L1of the cross section of the body4a, the lateral dimension of the cross section of the connecting end4bis not limited to this example. Further, althoughFIG.4illustrates the first pipe4in which the cross section of the connecting end4bis substantially elliptic, the cross section may alternatively be in the flattened shape other than an ellipse (for example, a rectangle with rounded corners, a polygon, or a track shape). The “track shape” described here means a shape of a race track in an athletic field. As illustrated inFIG.3, in the first pipe4of the present embodiment, the connecting end4bextends inside the casing3C and is in contact with an inner surface (here, the end surface on the vehicle outer side) of the casing3C. As such, by extending from the inlet opening3dto a deep inside of the casing3C and being arranged in contact with the inner surface of the casing3C, the connecting end4bhas a function of reinforcing the casing3C from the inner surface side of the casing3C. A large number of holes4dare formed through the connecting end4b. The exhaust gas that has flowed through the first pipe4further flows into the casing3C through these holes4d. As in the case of the first pipe4, the second pipe5is also formed in a substantially L-shape when viewed from the vehicle rear side (in a rear view). As illustrated inFIG.5, the second pipe5of the present embodiment includes a body5aextending in the vehicle width direction, a corner5ccurving upward from an end on the vehicle inner side of the body5a, and a connecting end5bconnected to the casing3C. The body5a, the corner5c, and the connecting end5bare continuous, and an extending direction of the body5ais orthogonal to an extending direction of the connecting end5b. In the present embodiment, the extending direction of the body5acoincides with the longitudinal direction (vehicle width direction) of the casing3C, and the extending direction of the connecting end5bcoincides with the lateral direction (if the casing3C is a cylinder, the radial direction) of the casing3C. As illustrated inFIG.2, in the present embodiment, a cross section of the body5aof the second pipe5is also substantially circular, and is uniform in the longitudinal direction (i.e., the vehicle width direction) of the body5a. Hereinafter, an outer diameter of the cross section of the body5ais defined as L2. As in the case of the first pipe4, the cross section of the second pipe5changes from the body5ato the connecting end5bvia the corner5c. Specifically, while the cross section of the body5ais substantially circular, as illustrated inFIG.5, a cross section of the connecting end5bis in a flattened shape as if the cross section of the body5ais crushed (narrowed). As illustrated inFIG.5, the cross section of the connecting end5bis in the flattened shape as a dimension (longitudinal dimension L2′) along the longitudinal direction of the casing3C is shorter than a dimension (lateral dimension) along the lateral direction of the casing3C. AlthoughFIG.5illustrates the second pipe5in which the lateral dimension of the cross section of the connecting end5bis equal to the outer diameter L2of the cross section of the body5a, the lateral dimension of the cross section of the connecting end5bis not limited to this example.FIG.5illustrates the second pipe5in which the cross section of the connecting end5bis in a substantial rectangle with rounded corners. It should be noted that the cross section of the connecting end5bmay be in another flattened shape (for example, an ellipse, a track shape, or a flattened polygon other than a rectangle). As illustrated inFIG.5, in the second pipe5of the present embodiment, the connecting end5bextends inside the casing3C and is in contact with the inner surface (here, the end surface on the vehicle inner side) of the casing3C. As such, by extending from the outlet opening3eto a deep inside of the casing3C and being arranged in contact with the inner surface of the casing3C, the connecting end5balso has a function of reinforcing the casing3C from the inner surface side of the casing3C. The connecting end5bof the second pipe5has an opening(s) in the casing3C, and through the opening(s), the exhaust gas that has passed through the SCR3A and the downstream oxidation catalyst3B in the casing3C flows into the second pipe5to be discharged to the outside. In the exhaust purification device1of the present embodiment, as illustrated inFIG.2, the first pipe4is connected to a lower and diagonally rear side of the casing3C, and the second pipe5is connected to a lower and diagonally front side of the casing3C. Accordingly, interference between the two pipes4and5are avoided. [3. Actions and Effects] In the exhaust purification device1described above, the inlet opening3dis provided at the first longitudinal end of the casing3C which accommodates the SCR3A and the downstream oxidation catalyst3B as the purifiers, and the outlet opening3eis provided at the second longitudinal end. In addition, the cross section of at least one of the connecting ends4band5bof the pipes4and5connected to these openings3dand3eis in the flattened shape as the longitudinal dimension L1′, L2′ along the casing3C is shorter than the lateral dimension L1, L2. As such, with the cross section of the connecting end4b,5bof the pipe4,5formed into the shape whose longitudinal dimension L1′, L2′ along the casing3C is shorter than the lateral dimension L1, L2, a longitudinal dimension occupied by the pipe4,5in the casing3C becomes small when the pipe4,5is connected to the longitudinal end of the casing3C. For example, assuming that the longitudinal dimension of the casing3C is 100, the shorter the longitudinal dimension L1′, L2′ of the connecting end4b,5bof the pipe4,5is, the closer to 100 the longitudinal dimension of the purifier arranged in the casing3C becomes. Therefore, by devising the pipe4,5connected to the casing3C, it is possible to shorten the casing3C while ensuring the size of the purifier. This enhances mountability on the vehicle and layout flexibility of not only the SCR device3but also the exhaust purification device1. Alternatively, if the longitudinal dimension of the casing3C is set to, for example, the maximum designable length, a purifier with larger capacity can be accommodated in the casing3C. According to the exhaust purification device1described above, since the connecting end4b,5bof the pipe4,5extends inside the casing3C and is in contact with the inner surface of the casing3C, the strength of the casing3C can be increased. According to the exhaust purification device1described above, since the connecting end4bof the first pipe4and the connecting end5bof the second pipe5are both in the flattened shape, the longitudinal dimensions occupied by the two pipes4and5in the casing3C become smaller. This enables the casing3C to be even shorter while ensuring the size of the purifier. Alternatively, if the casing3C is designed to have a predetermined length, a purifier with larger capacity can be accommodated in the casing3C. In the exhaust purification device1described above, since the casing3C accommodates the SCR3A that serves as the purifier, it is possible to secure the length of the SCR3A without enlarging the longitudinal dimension of the casing3C. This can lengthen the distance for the exhaust gas to pass through the SCR3A, which contributes to enhancement of the exhaust purification performance. In the exhaust purification device1described above, the casing3C is mounted on the vehicle in the orientation such that the longitudinal direction of the casing3C coincides with the vehicle width direction. In other words, even if the casing3C is arranged in such an orientation, according to the exhaust purification device1that adopts the connection structure of the pipe4,5described above, the length (capacity) of the purifier can be secured to enhance the exhaust purification performance while satisfying the vehicle width regulation. [4. Modifications] The configuration of the exhaust purification device1described above is an example. Although the exhaust purification device1described above illustrates a case where the connecting ends4band5bof the two pipes4and5are both in the flattened shape, as long as at least one of the connecting ends4band5bis in the flattened shape, the longitudinal dimension occupied by the pipe4,5in the casing3C can be small when the pipe4,5is connected to the longitudinal end of the casing3C. In addition, each shape of the cross sections of the bodies4aand5aof the pipes4and5is not limited to a circle. The connecting ends4band5bof the pipes4and5described above both extend inside the casing3C and are in contact with the inner surface of the casing3C, but the connecting ends4band5bmay be arranged in a non-contact manner with respect to the inner surface of the casing3C. Further, the connecting ends4band5bdo not have to extend inside the casing3C. For example, an opening may be provided at an end surface of the connecting end of the first pipe, and the connecting end may be connected to the casing3C so that the opening on this end surface communicates with the inlet opening3d. The connecting end of the second pipe may be configured in a manner similar to this. The purifier accommodated in the casing that adopts the structure of the connection portion described above is not limited to the SCR3A and the downstream oxidation catalyst3B. In other words, the above-described flattened shape may be applied to a cross section of a connecting end of a pipe that is connected to a casing which accommodates other purifiers instead of or in addition to the SCR3A and the downstream oxidation catalyst3B. The arrangement of the DPF device2and the SCR device3is not limited to the above. For example, these devices2and3may be oppositely arranged, may be arranged in parallel, or may be arranged so as to extend in the vehicle front-rear direction (along a substantially straight line). The method for fixing the DPF device2and the SCR device3to the vehicle body may be any method other than the one using the attachment member20described above. An exhaust purification device may be provided, which accommodates, in place of or in addition to the DPF device2and the SCR device3, another purifier such as an SCRF (Selective Catalytic Reduction on filter) with a filter coated with a selective reduction catalyst. When an exhaust purification device accommodating the SCRF instead of the DPF device2is provided, the reducing agent injector6described above may be provided on the casing that accommodates the SCRF. The cross-sectional area of the body4aand/or the cross-sectional area of the corner4cof the first pipe4can be made equal to the cross-sectional area of the connecting end4bin size. By setting the areas to be equal to each other in size (the areas almost equal in size are sufficient) as such, the flow rate of the exhaust gas can be substantially equalized between the body4aand/or the corner4cand the connecting end4b, and the resistance due to the change in the flow rate can be reduced. Similarly, the cross-sectional area of the body5aand/or the cross-sectional area of the corner5cof the second pipe5can be made equal to the cross-sectional area of the connecting end5bin size (the areas almost equal in size are sufficient). In this case as well, the resistance due to the change in the flow rate can be reduced in the same manner as described above. In this modification, the body4aand the corner4cof the first pipe, and the body5aand the corner5cof the second pipe each correspond to an outer pipe portion, but the outer pipe portion is not limited to these, and may be any pipe portions outside the casing that connects to the connecting end4bor the connecting end5b. The above-described embodiment regards the direction in which the exhaust gas in the second casing3C passes through the purifier as the longitudinal direction, and the direction orthogonal to the longitudinal direction as the lateral direction, but the present invention may be applied to a casing whose length along a direction in which the exhaust gas passes through the purifier is shorter than a length along an orthogonal direction to the direction in which the exhaust gas passes through the purifier, for example. Although the present specification mentions the longitudinal direction and the lateral direction, for convenience, the longitudinal direction expresses the direction in which the exhaust gas in the casing passes through the purifier, and the lateral direction expresses the orthogonal direction to the direction in which the exhaust gas in the casing passes through the purifier. DESCRIPTION OF REFERENCE SYMBOLS 1exhaust purification device3A SCR catalyst (purifier)3C second casing (casing)3dinlet opening3eoutlet opening4first pipe4bconnecting end5second pipe5bconnecting end | 24,889 |
11859530 | DETAILED DESCRIPTION FIG.1shows in a perspective front view an equalizing tank for a cooling circuit of a motor, in the present instance an electric motor, of a drive unit in the motor vehicle, such as an automobile. The equalizing tank in the present instance comprises a tank top piece1and a tank bottom piece2, which are removably joined together in the region of an encircling and sealing flange connection3. At the top of the housing top piece1, there is provided a fill nozzle4for the filling of coolant, especially water provided with antifreeze, being closed by a lid5. Furthermore, there can be seen inFIG.1a connection fitting6of an inlet line7, to be explained further below, for the coolant kept on hand in the equalizing tank and entering the equalizing tank from the cooling circuit tank. At this connection fitting6, a line of the cooling circuit can be attached, for example, by means of a pipe clamp or in another way. At the bottom of the tank bottom piece2there is a connection fitting8for an outlet line9, by which the coolant taken up in the equalizing tank can go from here to the cooling circuit of the drive motor. The equalizing tank serves in the present case for two goals in particular, namely, on the one hand, the equalizing of a temperature-dependent thermal expansion or change in volume of the coolant, and on the other hand the degassing of air which has been taken up in the coolant. In order to avoid air getting from the equalizing tank into the cooling circuit of the electric vehicle or its drive motor, it is particularly important for no lower pressure to arise inside the equalizing tank. This is a significant problem, especially at low temperatures in the cooling circuit. For this reason, in the present instance, as is moreover evident from a joint consideration ofFIGS.2a,2band2c, the inlet line7is provided separately from the tank top piece1on the inside.FIG.2ashows as a cutout view and in a cross sectional perspective front view the inlet line7mounted on the part1situated inside the equalizing tank, the inlet line7being further shown inFIG.2bseparately without equalizing tank and in an exploded perspective representation in2c. It is especially evident fromFIG.2cthat the inlet line in the present case is formed by a hose which for example is made of an elastically resilient plastic material. This hose10is received at least for one length region in a tubular or snorkel shaped holder11, which in turn is likewise configured separate from the equalizing tank, especially the tank top piece1, and is mounted thereon across an O-ring12. The hose10is connected fluid-tight to the connection fitting6, so that coolant introduced via the connection fitting6from the cooling circuit to the equalizing tank goes by way of the hose10to the interior of the equalizing tank. The holder11here is adapted to the trend of the inside of the equalizing tank and provided with corresponding recesses13. As is especially evident fromFIG.2a, the hose10and the holder11are connected to the tank top piece1, for example by suitable sliding connections, plug connections, or other kinds of connections, also for example with the aid of mechanical connection means such as detent elements, screws or the like. The hose10ends with an outlet opening14located in the area of the tank bottom piece2near a bottom end of the equalizing tank and near a surge wall15, preventing a direct overflow of the coolant9. One peculiarity of the present equalizing tank is now to be seen in that the inlet line7, especially its hose10, as well as the holder11, is configured as a separate structural unit from the tank top piece1and thus is or can be adapted individually to the respective circumstances of the cooling circuit for the drive motor. Thus, for example, and in particular, the length of the hose10can be varied, so as to control the flow rate of coolant in this way or adapt it to the flow rate going from the outlet line9to the cooling circuit. By an appropriate formation of the hose10in particular, a lower pressure in the equalizing tank can be prevented, so that air does not go from the equalizing tank to the cooling circuit. This has the advantage, in particular, that the tank top piece1can be used for multiple variant designs of cooling circuits or drive motors, only the particular inlet line7, in the present instance the hose10in particular, needing to be adapted to the specific conditions of the cooling circuit and the coolant. Hence, a respective hose10or a respective inlet line7can be arranged, specific to a variant design, on the tank top piece which is suitable for variant designs. In the present case, it is provided in particular that the holder11remains identical for some of the variant designs and in particular it has an identical length. Hence, in the present case, only the easily deflected hose10may need to be adjusted to the particular cooling circuit. Another embodiment of the equalizing tank is shown inFIGS.3aand3bin a cross sectional perspective front view and a perspective exploded representation, respectively; in the following, only the differences between the two embodiments shall be discussed, and otherwise the structural parts should have at least substantially the same configuration. The embodiment according toFIGS.3aand3bis distinguished in particular by the alternative design of the hose16, which in this case forms the inlet line7. In the present instance, the holder17is configured as a substantially duct-shaped or tubular front piece, being formed as a single piece with the tank top piece1of the equalizing tank. By contrast with the embodiment ofFIGS.2ato2c, therefore, no separate holder11is provided, but rather a holder17formed as a single piece with the tank top piece1, extending just as far as the region of the tank bottom piece. As can be seen fromFIG.3b, the hose16is inserted into the holder17, passing to the outside through a wall of the tank top piece1and forming in this region the fitting6for the cooling circuit or being connected to the connection fitting6. Furthermore, it can be seen fromFIGS.3aand3bthat the hose16extends to near the surge wall15in the area of the tank bottom piece2, and—as in the case of the embodiment ofFIGS.2ato2c— to near the lower end of the tank bottom piece2or that of the equalizing tank. FIG.3cshows in a cutout view and a cross sectional perspective front view the hose16, once again in the area of the connection fitting6, at which the equalizing tank is connected to the cooling circuit or a line of this cooling circuit. Also in the present case, the hose16is made from an elastically resilient plastic material. The tank top piece and the tank bottom piece1,2are also formed primarily from corresponding plastic materials, as are the holders11and17. Thus, also in the present instance, the hose17is configured as a separate structural unit from the tank top piece1and is held on it at the inside. German patent application no. 10 2021 118799.0, filed Jul. 21, 2021, to which this application claims priority, is hereby incorporated herein by reference, in its entirety. Aspects of the various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. | 7,632 |
11859531 | DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE DISCLOSURE FIG.1shows a drive system for a working machine, here a paver, according to the state of the art. In the state of the art pavers are equipped with a generator. The arrangement of the drive system consists of the internal combustion engine130with a crankshaft131. At least one hydraulic pump140is usually flanged to a power take-off135and drives a wide variety of consumers by means of at least one hydraulic valve141. An electric generator120is driven via the crankshaft131by means of a belt drive132. The generator120is for example used to heat a screed. Since the transferable power is limited by permissible transverse forces on the crankshaft bearing, this arrangement is disadvantageous. In the shown drive system1000according to an embodiment of the present disclosure inFIG.2, the known drive system according to the state of the art is additionally equipped with an auxiliary generator drive100for the belt driven generator120. The generator120is powered in normal state by the internal engine130. For higher loads the generator120is connected with a hydraulic motor110of the auxiliary generator100. The hydraulic motor110is arranged and adapted to drive the generator120and to be driven via a hydraulic pump140powered by the internal engine130. The hydraulic motor is driven directly by the hydraulic pump, connected via hydraulic valves141. With this embodiment the advantages of the belt drive being simple and economical are maintained while additional power can be delivered by the hydraulic motor. Thus advantageously, in the present embodiment, the belt drive can be maintained, but in a power-reduced version, so that the transverse forces on the drive motor are reduced, when an auxiliary generator drive in form of a hydraulic motor is used. In this embodiment in the predominant normal load cases, when the generator is only operated with medium power, the belt drive is used and embodies a highly efficient, simple and robust drive. Since the maximum or high generator output is only called up intermittently (e.g. in the heating-up phase at the start of work), the additional output may be required for this is transmitted using the hydraulic motor as a hydrostatic auxiliary drive. The hydraulic motor is driven directly via the hydraulic pump. Thus the hydraulic motor can react to a power demand of the generator without power limitations of intermediate elements like for example accumulators. The hydraulic motor in this embodiment can be driven by the internal engine via the (existing) hydraulic pump. As in the high load situations, only a few of the other hydraulic drives of a working machine are typically in operation, the hydraulic motor can be driven by existing hydraulic components with the internal engine. Thus no additional engine is needed and high loads of the generator can be provided with a relatively compact system with only an additional hydraulic motor. Thus, the additional drive relieves the belt drive and is itself powered by the already present internal engine130and the further hydraulic components, hydraulic pump140and hydraulic valves141. The hydraulic motor is connected to the hydraulic pump via at least one hydraulic valve. Hydraulic valves are widely used in existing working machines for different applications. The use of hydraulic valves, especially of a pressure control valve or a flow control valve has the advantage to be able to control the power output of the hydraulic motor and thus the auxiliary generator drive precisely. For the hydraulic motor110existing hydraulic valves141of an existing drive system can be used, as when the hydraulic motor is in use most other hydraulic applications are not. Alternatively, a dedicated hydraulic pump or a dedicated hydraulic valve can be used. In the embodiment illustrated, the hydraulic pump140is connected to the internal engine130, which may be a combustion engine, via a power-take off135. Combustion engines are widely used in existing working machines. Thus this embodiment can be used with existing drives. No new drive systems are required. As shown, the hydraulic motor110is flanged to the generator120by means of a one-way clutch115. Installation is shown at the free shaft end of the generator shaft125, but alternative arrangements can be utilized, such as, for example, coupling the hydraulic motor to the pulley. The freewheel may be designed such that the hydraulic motor110can drive the generator120but is not driven by the generator. This prevents drag losses when the hydraulic motor is not activated. Although a dedicated hydraulic motor110may be provided, advantageously since the other working hydraulic functions of a paver are hardly used in heavy heating operation, the hydraulic motor110can be one that powers other hydraulic functions when not driving the generator110. In the shown embodiment the hydraulic motor110may be controlled from an existing circuit of hydraulic components (hydraulic pump140and hydraulic valves141) by means of a pressure control valve142. In the version shown here, additional torque (pressure control) can be controlled in a defined manner. The forces in the belt drive can thus be reduced in a targeted manner. The hydraulic motor can also be connected to the hydraulic pump via a flow control valve. These embodiments also allow a defined torque to be applied by the hydraulic motor, i.e. the additional torque provided by the hydraulic motor is controlled and regulated via pressure or flow control for the hydraulic motor. Furthermore in an embodiment not shown here the hydraulic motor is a variable-displacement motor, which allows for further variation and control of the torque. As the variable-displacement motor provides variable torque and variable speed. With input flow and pressure constant, the torque speed ratio thus can be varied and controlled to meet load requirements by varying the displacement. Furthermore the hydraulic motor110can be monitored by a pressure sensor143and the generator power can be reduced if the belt forces are exceeded. The hydraulic motor can be adapted in an embodiment to be operated in a closed hydraulic circuit with the hydraulic pump, which allows for higher speed and is favourable for the use in vehicle and working machines. Working machines, especially pavers occasionally need high generator output in some working situations. This higher output can be favourably provided by the drive system with an auxiliary generator drive according to the described embodiments. In one embodiment, a method for operating a working machine, such as a paver, comprising an internal engine coupled to a generator via a crankshaft and a belt drive and an auxiliary drive comprising a hydraulic motor, the hydraulic motor is arranged and adapted to drive the generator and to be driven via a hydraulic pump by the internal engine, as described above, comprises determining an output demand for the generator, based on the output demand for the generator activating the auxiliary drive if a predetermined output demand is exceeded. In a further embodiment of the method the auxiliary drive is activated additionally to the to the belt drive and a speed of the internal engine may be reduced when the auxiliary drive is activated. This allows to spare the belt drive and the internal engine and reduces noises. FIG.3shows a second embodiment of a drive system2000according to the disclosure. In this embodiment the generator220is decoupled from the belt drive by means of a second one-way clutch221, which is arranged between generator shaft225and belt drive232. Thus the generator220can also rotate faster than specified by the belt drive232. The further components of this embodiment correspond to the embodiment shown inFIG.2. The hydraulic motor210is connected via a first one-way clutch215to the generator220and is arranged and constructed to drive the generator220. The hydraulic motor210itself is driven by the internal engine230via the hydraulic pump240and the hydraulic valve241. The hydraulic pump240is connected to the internal engine230via a power-take off235. Favourably, the hydraulic motor210should in this arrangement be operated at a defined speed, e.g. is set by a flow control valve242. However, speed control is also possible with the aid of the previously mentioned pressure control valve, shown in the embodiment ofFIG.2. In this embodiment, the generator220can be driven only by the additional hydraulic drive200. In this case the internal combustion engine230remains e.g. at a low speed, although the generator220is operated at a high speed. For example the generator220can turn around driven by the additional hydraulic drive200to generate a desired voltage frequency. This is advantageous for example if electrical tools are to be operated on the generator network (e.g. 230V, 50 Hz). One-way clutches on the generator allow the speeds to be decoupled in such a way that mutual hindrance is excluded. In this embodiment the generator is decoupled from the belt drive by means of the second one-way clutch, so that it can also rotate faster than specified by the belt drive. In this embodiment, the generator may optionally only be driven via the hydraulic motor. Then the internal combustion engine remains e.g. at a low speed, although the generator is operated at a high speed. In this embodiment, when the generator is coupled to the belt drive via a second one-way clutch, the auxiliary generator drive can be activated with higher speed than the speed of the belt drive, if the predetermined output demand is exceeded. Thus the speed of the generator is determined by the hydraulic motor only and the belt is decoupled to allow for higher speed than specified for the belt. With the embodiments of the disclosure described above the advantages of a belt-driven generator are retained. The auxiliary drive only has to be used if a large generator output is occasionally called up. Furthermore the auxiliary drive can be used to operate the drive motor at low speed, which also means at low noise and high efficiency. A possibly required high generator speed can be generated via the additional drive and thus the belt drive is spared. The internal engine thus determines the generator speed if there is sufficient motor speed and the generator power is sufficient. The auxiliary generator drive on the other hand determines the generator speed if the drive motor speed should only be low, which means in situations when low noise and/or high efficiency is required and the belt drive should be spared. This thus allows the belt drive to be used to drive the generator at lower speeds and with lower tensioning and allows the hydraulic motor to augment the power of the belt drive, such as for example when peak generator power is required, such as, for example, when first heating up the paver screed. It is to be understood that the drive system for a working machine, the method for operating a working machine, the computer program, the computer readable medium and the control unit for a working machine according to the further aspects of the disclosure share the advantages of the additional generator drive according to the disclosure. It is further to be understood that the present disclosure is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims. | 11,533 |
11859532 | DETAILED DESCRIPTION OF THE INVENTION The present invention proposes to use the free-piston engine (FPE) as a vibratory plate engine. In the section “FIELD OF THE INVENTION” it is stated that in accordance with the purposes of the present invention, FPEs similar to those depicted inFIGS.1and2are used to drive the vibratory plate. These are FPEs, in which an unbalanced piston2moves in cylinder1. The piston is one part, or, in another formulation, all points of the piston have practically the same speed relative to the cylinder.FIGS.1and2show the vertical mounting of such an FPE on a vibratory plate. For the vibratory plate, the FPE with two working cavities (with two combustion chambers) can be used (seeFIG.6). This refers to the combustion chambers on both sides of the piston2(one chamber is between the piston and one of the cylinder heads, the second is between the piston and the second cylinder head). In this case, combustion (engine cycle) takes place in both chambers. Also, another FPE can be used, it is FPE, in which one cavity (one combustion chamber) is the working (combustion) cavity, and the other cavity is a compressor chamber (this chamber can also be called a buffer chamber). Said FPE version (suitable for driving the vibratory plate, for use as the vibratory plate engine) is described below. As seen inFIGS.1,2, the working chamber5(combustion chamber5) is located in the lower (bottom) part of the FPE (between piston2and the bottom head3of cylinder1), and the compressor chamber6is in the upper part of the FPE (between piston2and the upper cylinder head). In other words, the combustion chamber is located between the piston and the cylinder head that is closer to the plate of the vibratory plate, the cylinder head that is fixed to this plate, and the compressor (buffer) chamber (cavity) is located on the other side of the piston (located between the piston and the opposite head). In this FPE, the piston moves reciprocally, and the cylinder1(FIGS.1,2) performs reciprocating movements opposite to the movements of the piston2. The cylinder is mounted vertically and fixed to the plate8(FIG.2). In each engine cycle after combustion into a bottom chamber5(FIG.1a) the gas pressure acts on the piston and on the cylinder (the gas pressure on the piston2and on the bottom cylinder head3is shown by small arrows), the piston moves up (hereinafter, the direction of movement is shown by the large arrow on the piston) and the cylinder1moves down under the action of gas pressure. Since the cylinder1is fixed to the plate8(seeFIG.2), plate also moves downward and compacts soil, gravel, etc. Depicted onFIG.1a, combustion and expansion processes in the bottom chamber can be considered as the power stroke, in which the piston moves upward under the pressure of the combustion products. Above the piston in the compressor chamber (cavity)6at this time (FIG.1a) a part of the air is pushed out of the cylinder through the exhaust port4. It is possible a scavenging of the cylinder due to the use of gas-dynamic phenomena, in particular, due to the correct choice of lengths and other sizes of intake and exhaust pipes (manifolds) (is not shown in the figures). To prevent the backflow of fresh air from the compressor chamber6through the port7, a valve can be mounted on this port, for example, a check valve (reed valve) shown inFIG.2. A gas dynamic valve can also be used. This valve has a lower resistance to the flow of air entering the cylinder than the resistance to the flow of air out of the cylinder. The gas dynamic valve may be similar to the Tesla gas dynamic valve. In the combustion chamber5, in the bottom part of the cylinder1, while the piston continues to move upward (seeFIG.1b), the piston opens the exhaust port4, and the combustion products (their movement is shown by the black arrow) flows out of the cylinder (from the combustion chamber5) into the port4. Above the piston in the compressor chamber6(seeFIG.1b) while further movement of the piston, the latter closes the intake port7, and air compression begins in the compressor chamber. During compression, the piston moves upward by inertia. Further compression of air in the compressor chamber6while the piston continues to move upward by inertia is shown inFIG.1c. As is clear fromFIG.1c, in the lower part of cylinder1, between the bottom head3of cylinder1and piston2, the continuing increase in the volume of the combustion chamber5and, therefore, the expansion of gases leads to a drop in pressure in this chamber below atmospheric, and air is sucked into the cylinder through the intake port7, into the combustion chamber5. Further, the piston, continuing its upward movement, continues to compress the air in the chamber6(between the upper head of the cylinder1and the piston2). The pressure in the chamber6increases, the piston stops and begins to move in the opposite direction, down. This movement is shown inFIG.1d. After the piston closes the inlet port7(seeFIG.1d), the intake into the combustion chamber5is stopped and a part of the previously entered air and residual combustion products are displaced through the exhaust port4. Further, while the piston moves down, the lower edge of the piston2(seeFIG.1e) passes through the port4, and compression begins in the chamber5; after compression (FIG.1a), fuel self-ignition and combustion occur in chamber5. And the engine cycle is repeated. In chamber6(seeFIG.1e), when the piston moves downward after piston2passes port7, ambient air enters through port7into compressor chamber6. Then, in this chamber, the engine cycle is repeated, i.e. the piston moves upward (FIG.1a), etc. The FPE under consideration can operate both on a diesel cycle with fuel injection into the combustion chamber (into the combustion chambers) and self-ignition of fuel, and when ignited from an external source (from a spark). FPE can run on gasoline, diesel and, due to its high compression ratio, many other fuels. This FPE has a regulated fuel supply. An increase in the fuel supply leads to an increase in the combustion pressure, therefore (seeFIG.1a) to an increase in the force of the plate impact on the rammed material: soil, gravel, asphalt, tiles (for sidewalks), etc. Also, an increase in combustion pressure increases the frequency of FPE operating cycles, hence the frequency of impacts of the plate on the rammed material. The FPE considered above or a similar FPE in which the unbalanced piston2is reciprocating in cylinder1is used as an engine of the vibratory plate (FIG.2). Cylinder1FPE is fixed to plate8rigidly either through a spring or through spring washers. InFIG.2the lower part of the cylinder1has a circular projection (disc)10. The cylinder and disc10are integral (one piece). For example, they can be made (turned) from one piece of metal. In the FPE shown inFIG.2, the disc10and the plate8of the vibratory plate are tightened (connected, fixed) with bolts11, which ensures a rigid connection between the cylinder and the plate. InFIG.2shows that the cylinder is mounted vertically on the plate of the vibratory plate. In an embodiment, the attachment of the cylinder to the plate is performed with an inclination relative to the perpendicular to the plate8, so that there is an angle between the axis of the cylinder and the perpendicular to the plane of the plate. The tilt of the cylinder serves to move the vibratory plate horizontally while ramming (in the process of ramming); move means moving along the rammed area. In a further embodiment, the fixing of the cylinder to the plate is made with the possibility of changing the specified inclination. A stepwise, discrete change in inclination is possible (of course, with the cylinder fixing in discrete tilts), for example, the cylinder can be installed in three positions (relative to the horizontal plate of the vibrating plate): vertical, inclined forward, inclined back. Depending on the inclination, the vibratory plate ramps the soil, etc., remaining in place, moving forward, moving back. Obviously, it is possible to produce a variant of a vibratory plate with smooth regulation of the cylinder tilt angle. This means setting the desired tilt angle and fixing the cylinder at the selected tilt angle. Among the mechanisms for changing the angle between the axis of the cylinder and the perpendicular to the plane of the plate, the following can be considered. The cylinder is mounted obliquely on an auxiliary part (or auxiliary plate), which can be rotated around a vertical axis. | 8,553 |
11859533 | It is noted that the drawings of the disclosure are not necessarily to scale. The drawings are intended to depict only typical aspects of the disclosure and therefore should not be considered as limiting the scope of the disclosure. In the drawings, like numbering represents like elements between the drawings. DETAILED DESCRIPTION As an initial matter, in order to clearly describe the subject matter of the current disclosure, it will become necessary to select certain terminology when referring to and describing relevant machine components within a turbine system, such as but not limited to a gas turbine engine system. To the extent possible, common industry terminology will be used and employed in a manner consistent with its accepted meaning. Unless otherwise stated, such terminology should be given a broad interpretation consistent with the context of the present application and the scope of the appended claims. Those of ordinary skill in the art will appreciate that often a particular component may be referred to using several different or overlapping terms. What may be described herein as being a single part may include and be referenced in another context as consisting of multiple components. Alternatively, what may be described herein as including multiple components may be referred to elsewhere as a single part. In addition, several descriptive terms may be used regularly herein, and it should prove helpful to define these terms at the onset of this section. These terms and their definitions, unless stated otherwise, are as follows. As used herein, “downstream” and “upstream” are terms that indicate a direction relative to the flow of a fluid, such as the working fluid through the turbine engine or, for example, the flow of air through the combustor or coolant through one of the turbine's component systems. The term “downstream” corresponds to the direction of flow of the fluid, and the term “upstream” refers to the direction opposite to the flow (i.e., the direction from which the flow originates). The terms “forward” and “aft,” without any further specificity, refer to directions, with “forward” referring to the front or compressor end of the engine, and “aft” referring to the rearward section of the turbomachine. It is often required to describe parts that are disposed at differing radial positions with regard to a center axis. The term “radial” refers to movement or position perpendicular to an axis. For example, if a first component resides closer to the axis than a second component, it will be stated herein that the first component is “radially inward” or “inboard” of the second component. If, on the other hand, the first component resides further from the axis than the second component, it may be stated herein that the first component is “radially outward” or “outboard” of the second component. The term “axial” refers to movement or position parallel to an axis. Finally, the term “circumferential” refers to movement or position around an axis. It will be appreciated that such terms may be applied in relation to the center axis of the turbine. In addition, several descriptive terms may be used regularly herein, as described below. The terms “first,” “second,” and “third,” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur or that the subsequently describe component or element may or may not be present, and that the description includes instances where the event occurs or the component is present and instances where it does not or is not present. Where an element or layer is referred to as being “on,” “engaged to,” “connected to” or “coupled to” another element or layer, it may be directly on, engaged to, connected to, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Gas turbine fuels can range from natural gas and high-quality liquid distillate fuels to crude oils and low-grade refinery residues and combustible residual gases from some processes like steel manufacturing. For some gas turbine fuels, there may be additives needed for efficiency and effective operation of a gas turbine. Additives can vary based on the fuel type and the nature and quantity of contaminants from all sources that enter the gas turbine. Additional factors for additive selection, such as but not limited to firing temperature and original equipment manufacturer (OEM) specifications, are also considered. Many fuel additives are intended to control high temperature corrosion and ash fouling of gas turbine hot gas path section components. Several different corrosion mechanisms can occur during combustion, and generally may be attributed to formation of low melting point ash deposits. These ash deposits may originate from trace metal impurities in gas turbine fuels. For example, heavy fuel oils (HFOs), including but not limited to crude oils and residual-grade fuel oils, typically contain quantities of vanadium (V). Vanadium is a naturally occurring component of petroleum. During combustion, fuels including vanadium may create vanadic ash deposits. Vanadic ash deposits are formed mainly of vanadium pentoxide (V2O5), and have a “low” melting point of about 675° C. (1247° F.). At typical gas turbine operating temperatures, vanadic ash deposits are molten. Being molten, vanadic ash deposits may accelerate surface oxidation rate of hot gas path components of gas turbines. Gas turbine hot gas path components include, but are not limited to combustion liners, transition pieces, turbine nozzles, turbine blades, and turbine vanes. Other trace metal impurities, such as lead, and zinc, may also initiate high temperature corrosion, by similar mechanisms. Alkali metal impurities, namely sodium (Na) and potassium (K), can also cause high temperature corrosion, known as sulfidation corrosion. Sulfidation corrosion involves formation of sodium sulfates, through reaction with fuel sulfur. Sulfidation corrosion results in inter-granular pitting of gas turbine hot gas path components, which is metallurgically undesirable. In certain regions, especially the Middle East, vanadium and sodium impurities are common in fuel. Thus, lower melting point ash deposits can readily form in a gas turbine system in this region. Accordingly, with non-treated or additive free gas turbine fuel from these regions, a risk of high temperature corrosion in a gas turbine system is increased. Sodium and potassium salts are water-soluble and can be removed (or at least reduced to within acceptable specification limits) by on-site treatment processes. These on-site treatments processes are known as “fuel washing.” Distillate-grade fuels are not typically washed at the gas turbine power plant. Distillate-grade fuels may often be delivered containing some amount of contamination, such as but not limited to sodium contamination. Moreover, vanadium and other oil-soluble trace metals cannot be removed by fuel washing. Corrosion inhibition processes and treatments to remove some contamination, such as but not limited to vanadium contamination, may have to be achieved using chemical additives, as described herein. Liquid fuels are not the only source of ash-forming impurities or contamination. Sodium salts and other contaminants can be found in gas turbine fuel and thusly enter gas turbine engine systems in various manners. Contaminants may enter a gas turbine engine system from gas turbine fuel, from compressor inlet air, from water and steam that may be injected for nitrogen oxide (NOx) control, from power augmentation steps, and/or from other such sources. Thus, risk of contamination from non-fuel sources should also be considered in gas turbine engine system applications. Fuel additives that include magnesium (Mg) can be used to control vanadic ash deposits and vanadic oxidation. Magnesium can modify vanadic ash composition and increase vanadic ash melting points, which reduces the possibility of molten vanadium causing issues. Through combination with V2O5at an appropriate magnesium-to-vanadium (Mg/V) treatment ratio, magnesium ortho-vanadate [3MgO·V2O5] is formed as a new ash component. 3MgO·V2O5has a high melting point of about 1243° C. (2269° F.). Accordingly, with 3MgO·V2O5vanadic ash corrosion of a gas turbine engine system is limited and controlled. By ensuring that vanadic ash as a combustion ash does not melt and remains in a solid state on gas turbine blades and vanes, vanadic ash corrosion can be reduced. Through reaction with sulfur in gas turbine fuel, magnesium inhibition mechanisms through formation of 3MgO·V2O5also generate magnesium sulfate (MgSO4) as an additional ash component. MgSO4is water-soluble. Thus, MgSO4facilitates removal of combustion ash through periodic water washing of gas turbine hot gas path components. The removal of combustion ash can enable power to be recovered that may have been lost due to ash formation on gas turbine hot gas path components. Chromium (Cr) additives for gas turbine fuels can inhibit sulfidation corrosion promoted by alkali metal contaminants, such as, but not limited to, sodium and potassium. Chromium additives have also been shown to reduce ash fouling. Chromium additive ash fouling reduction may involve formation of volatile compounds with contaminants, which pass through the gas turbine without depositing on hot gas path components. Moreover, additives can include chromium alone, or can be in combination with magnesium and other constituents. Additives containing silicon (Si) can also be added to provide added corrosion protection and improved ash friability from hot gas path components of a gas turbine system. Magnesium additives are of a sulfonate type chemistry. Sulfonate type chemistry in ash formation is resistant to hydrolysis. Any tendency for gel formation of sulfonate type additives because of water contact with sulfonate ash formations is extremely low. Thus, sulfonate type chemistry additives can mitigate plugging of gas turbine system components, including but not limited to, filters, flow dividers, nozzles, blades, and/or fuel nozzles. Sulfonate type additives also enable high reactivity during combustion. The high reactivity may permit magnesium to be consumed more efficiently during vanadium inhibition. This high reactivity may be due to extremely small particle sizes of sulfonate type additives, where the particle size of sulfonate type additives are about 5 times smaller than magnesium carboxylate (C10H12MgN2O6) particles. Accordingly, sulfonate magnesium additives can be safely added to gas turbine fuel, thereby ensuring protection without over-treatment. As used in this application, “offline washing” is where the gas turbine is spun by an external crank, and the gas turbine is in a cooled state using cranking speed. When a gas turbine is off-line, it is not burning fuel or supplying power. As embodied by the disclosure, conversely, an online process is conducted with the gas turbine being at an operating temperature, burning fuel and supplying power. Referring now to the drawings, in which like numerals refer to like elements throughout the several views,FIG.1illustrates a schematic view of gas turbine engine system or gas turbine engine system10, as embodied by the disclosure. Gas turbine engine system10may include a compressor15. Compressor15compresses an incoming flow of air20after air20flows through inlet filter house15′. Compressor15delivers the compressed flow of air20to a combustor25. Combustor25mixes the compressed flow of air20with a pressurized flow of fuel30and ignites the mixture to create a flow of combustion gases35. Although only a single combustor25is shown, gas turbine engine system10may include any number of combustors25. The flow of combustion gases35is in turn delivered to a gas turbine40. The flow of combustion gases35drives gas turbine40to produce mechanical work. Mechanical work produced in gas turbine40drives compressor15via a shaft45and an external load50, such as but not limited to, an electrical generator and the like. Gas turbine fuels can range from natural gas and high-quality liquid distillate fuels to crude oils and low-grade refinery residues. Gas turbine engine system10may be any one of a number of different gas turbine engines offered by General Electric Company of Schenectady, N.Y., including but not limited to, those such as a 7 or a 9 series heavy duty gas turbine engine, an H class series heavy duty gas turbine engine, such as an HA gas turbine engine, and the like. The gas turbine engine system10may have different configurations and may use other types of components. Other gas turbine engines may also be used herein. Multiple gas turbine engines, other types of turbines, and other types of power generation equipment also are also within the scope of the embodiments described herein. FIG.2is an example of a compressor15as may be used with gas turbine engine system10and the like. Compressor15may include a number of stages55. Although eighteen stages55are shown, any number of stages55may be used. Each stage55includes a number of circumferentially arranged rotating blades60. Any number of blades60may be used. Blades60may be mounted onto a rotor wheel65. Rotor wheel65may be coupled to shaft45(FIG.1) for rotation therewith. Each stage55also may include a number of circumferentially arranged stationary vanes67. Any number of vanes67may be used. Vanes67may be mounted within an outer casing70. Outer casing70may extend from a bellmouth75towards gas turbine40. The flow of air20(FIG.1) thus enters compressor15about bellmouth75and is compressed through blades60and vanes67of stages55before flowing to combustor25(FIG.1). Bellmouth75may be provided with water wash injection nozzles (not illustrated for ease of understanding and clarity) for applying water and/or detergents to compressor blades60and vanes67of stages55. However, the water and/or detergent may not flow to all blades60and vanes67of stages55of compressor15. Moreover, compressor water wash systems do not provide a direct path to gas turbine components, including but not limited to hot gas path components including stage one nozzles (S1N) and stage 2 nozzles (S2N), as well as associated wheel space cavities of gas turbine40(FIG.1) that may get contamination thereon. Accordingly, as embodied by the disclosure, providing injection points for washing gas turbine components, including but not limited to hot gas path components including stage 1 nozzles (S1N) and stage 2 nozzles (S2N), as well as associated wheel space cavities, may be obtained by locating injection closer to the gas turbine itself. With reference toFIG.3, a combustor25includes a first interior21in which a first fuel supplied thereto by fuel circuit is combustible, and a transition zone43to gas turbine40. Gas turbine40includes rotating turbine blades and nozzles in stages, into which products of at least the combustion are receivable to power rotation of turbine blades. The transition zone43fluidly couples combustor25to turbine40. Transition zone43includes a second interior41into which a second fuel is supplied to further the combustion. As shown, combustor25and transition zone43combine with one another to generally have a form of a head end11. As illustrated inFIG.3, head end11may include multiple premixing nozzles12. However, other head end11configurations are possible. It is understood that versions of other head end11configurations may be late lean injection (LLI) or axial fuel staging (AFS) combustors (to be described hereinafter with respect to secondary fuel injected into combustor25AT fuel injectors60) compatible. For purposes of this description, LLI and AFS are similar and equivalent. An LLI compatible combustor is a combustor with either an exit temperature that exceeds about 2500° F. or about 1370° C., or a combustor that handles fuels with components that are more reactive than methane with a hot side residence time greater than 10 milliseconds (ms). A plurality of late lean fuel injectors60are structurally supported by an exterior wall of transition zone43or by an exterior wall of a sleeve42around transition zone43and extend into second interior41to varying depths. With this configuration, fuel injectors60may be configured to provide late lean injection (LLI) fuel staging capability. That is, fuel injectors60are each configured to supply a second fuel (i.e., LLI fuel) to second interior41by, e.g., fuel injection in a direction that is generally transverse to a predominant flow direction. Fuel injectors60may inject fuel in this manner through transition zone43, in any one of a single axial stage, multiple axial stages, a single axial circumferential stage, and/or multiple axial circumferential stages. Conditions within combustor25and transition zone43are thus staged to create local zones of stable combustion. As embodied by the disclosure, an aspect provides a single axial stage that includes operating a single fuel injector60. Alternatively, multiple axial stages may be operated at multiple axial locations at transition zone43. Further, embodiments may include a single axial circumferential stage operating fuel injector60disposed around a circumference of a single axial location of transition zone43. In other embodiments, multiple axial circumferential stages may be operating fuel injectors60disposed around a circumference of the transition zone43at multiple axial locations. Here, where multiple fuel injectors60are disposed around a circumference of transition zone43, fuel injectors60may be spaced substantially evenly or unevenly from one another. As a non-limiting illustration, eight or ten fuel injectors60may be disposed at a particular circumferential stage, and for example with two, three, four or five or more fuel injectors60installed with varying degrees of separation from one another around transition zone43. Also, where multiple fuel injectors60are disposed at multiple axial stages of transition zone43, fuel injectors60may be in-line and/or staggered with respect to one another. During operations of gas turbine engine system10, each fuel injector60may be jointly or separately activated or deactivated to form one of the single axial stage, the multiple axial stages, the single axial circumferential stage, and the multiple axial circumferential stages. Thus, in an aspect of the embodiments, fuel injectors60each may be supplied with LLI fuel by a fuel injector60port or valve61(hereinafter “valve”61) disposed between a corresponding fuel injector60and a fuel circuit. Valve61signal communicates with a controller80that sends a signal to valve61that causes the valve61to open or close and to thereby activate or deactivate corresponding fuel injector60. Thus, if each fuel injector60is to be simultaneously activated (i.e., multiple axial circumferential stages), controller80signals to each of the valves61to open and thereby activate each of the fuel injectors60. Conversely, if each fuel injector60of a particular axial stage of transition zone43is to be activated (i.e., single axial circumferential stage), controller80includes an element (e.g., but not limited to an electro-mechanical transducer) configured to convert an electrical signal from controller80to a corresponding adjustment to valves60,61. Signals to each of valves61may correspond to only the fuel injectors60of the single axial circumferential stage to open and thereby activate each of the fuel injectors60. Of course, this control system is merely illustrative and it is understood that multiple combinations of fuel injector configurations are possible and that other systems and methods for controlling the activation and deactivation of at least one of fuel injectors60are available. In accordance with another aspect of the disclosure, a method of operating a gas turbine engine system10, in which a turbine40is fluidly coupled to a combustor25by a transition zone43interposed therebetween, is provided. The method includes supplying a first fuel to a first interior21within combustor25, combusting the first fuel in first interior21within combustor25, supplying a second fuel to second interior41within transition zone43in any one of a single axial stage, multiple axial stages, a single axial circumferential stage and multiple axial circumferential stages, and combusting the second fuel and a stream of combustion products, received from first interior21, in second interior41within the transition zone. Supplying of the second fuel to second interior41in the single axial stage may include activating a single fuel injector60. Supplying the second fuel to the second interior41in the multiple axial stages may include activating multiple fuel injectors60respectively disposed at multiple axial locations of the transition zone43. Supplying the second fuel to second interior41in the single axial circumferential stage also includes activating multiple fuel injectors60respectively disposed around a circumference of transition zone43at a single axial location thereof. Additionally, supplying the second fuel to second interior41in the multiple axial circumferential stages includes activating multiple fuel injectors60disposed around a circumference of transition zone43at multiple axial locations thereof. FIG.4shows a wash system100as embodied by the disclosure. Wash system100may include a water source110. The water source110may have any size, shape, or configuration. The water source110may have a volume of water120therein. Wash system100also may include a detergent source130. The detergent source130may have any size, shape, volume, or other configuration. The detergent source130may have a supply of a detergent140therein. The detergent140may be any type of cleaning solution. The detergent140may be diluted with the water120in a predetermined ratio. In another aspect of the embodiments, wash system100also may include a chemical source150. Chemical source150may have any size, shape, or configuration. In certain embodiments, chemical source150may have a volume of an anti-static solution160therein. Anti-static solution160may be any type of anti-static fluid. Anti-static solution160may be diluted with the water120in a predetermined ratio. Water source110, detergent source130, and/or chemical source150may be positioned on a wash skid165in whole or in part. Wash skid165may be mobile and may have any size, shape, or configuration. Other components and other configurations may be used herein. Each source110,130and150are referred to in general as a “source” and may provide particular wash materials, such as, but not limited to, being a water source110; a detergent source130; and a solution or chemical source150. Each source110,130, and150may include level sensors (not illustrated inFIG.3, seeFIG.6) to provide an indication of source content level. Moreover, as used herein, source(s)110,130, and150may be referred generally as a “source” or alternatively, with respect to particulars of the wash material(s) it may include. Wash system100also may include a mixing chamber170. Mixing chamber170may be used to mix detergent140with water120, or anti-static solution160with water120. Other combinations of fluids may also be used. Non-diluted fluids also may be used herein.FIG.5illustrates a non-limiting illustrative mixing chamber170. Mixing chamber170may include one or more of angled counter flow nozzles180for the flow of detergent140and/or anti-static solution160or other type of secondary flows. Flow of detergent140or anti-static solution160may be injected at a non-diametrically opposed or counter angle via angled counter flow nozzles180into an incoming flow of water or other type of primary flow for good mixing therein without the use of moving parts. Effective mixing also may be provided by injecting flow of detergent140or anti-static solution160at a higher pressure as compared to flow of water120. Mixing chamber170may have any size, shape, or configuration. The one or more angled counter flow nozzles180extend into the mixing chamber at an angle with respect to a central axis of mixing chamber170and can be configured to inject a first fluid at an angle in a direction counter to a flow of the water in mixing chamber170. As shown inFIG.4, water source110may be in communication with mixing chamber170via a water line190. Water line190may have a water pump thereon. Water pump may be, e.g., of conventional design. Water line190may have a pair of water line isolation valves210thereon. Detergent source130may be in communication with mixing chamber170via a detergent line220. Detergent line220may have a detergent pump230thereon. Detergent pump230may be, e.g., of conventional design. Detergent line220may have a pair of detergent line isolation valves240thereon. Anti-static solution source160may be in communication with mixing chamber170via an anti-static solution line250. Anti-static solution line250may have an anti-static solution pump260thereon. Anti-static solution pump260may be of conventional design. Anti-static solution line250may have a pair of anti-static solution line isolation valves270thereon. Other components and other configurations may be used herein. Wash system100also may include a conduit or line340, i.e., an output line from mixing chamber170. In this example, with respect toFIGS.3and4, line340leads from skid165to one or more of valves61for late lean injection (axial fuel staging) in combustor25. Thus, wash materials, such as at least one of water120, detergent140, anti-static solution160, and passivation solution (to be described hereinafter) can be fed to combustor25. When fed to combustor25at valves61for late lean injection, wash materials are proximate hot gas path components of gas turbine40, and in particular S1N of gas turbine40. Therefore, as at least one of washing, detergent, anti-static, and passivation solution materials can proceed to late lean injectors valves61of gas turbine40(FIG.4) via combustion gas35(FIG.1) streams to act on and clean gas turbine40components, including but not limited to, blades and nozzles of gas turbine40. With respect toFIGS.4and6, a wash controller380may operate wash system100. Wash controller380may provide at least one of water120, detergent140, anti-static solution160, and/or passivation solution (as described hereinafter) to mixing chamber170and then to combustor25in appropriate ratios thereof. Wash controller380may be any type of programmable logic device (as discussed hereinafter) and may be in communication with or part of an overall control system of gas turbine engine system10. Specifically, wash controller380may control valve interlocks, fluid levels, pump operation, connectivity signals, flow sensors, temperature, pressure, timing, and the like, as discussed herein. Various types of sensors (such as but not limited to, thermometers, flow meters, pressure sensors, and the like.) may be used herein to provide feedback to wash controller380. Access to wash controller380and operation parameters herein may be restricted to ensure adequate cleaning and coverage. In use, wash skid165with fluid sources110,140,150may be positioned adjacent gas turbine engine system10(FIG.1). Alternatively, the fluid sources110,140,150may be more permanently located nearby in whole or in part, to gas turbine engine system10. In certain aspects of the embodiments, wash controller380may determine a ratio of water120to detergent130. Wash controller380may activate water pump220and/or detergent pump230to pump corresponding volumes of water120and detergent140to mixing chamber170. A portion of a detergent/water mixture from mixing chamber170may flow through conduit or line340to a connection with one or more of valves61of combustor25for resultant flow to S1N of gas turbine40. Flow may occur with gas turbine40off-line with gas turbine40under cranking power to permit flow from combustor25to gas turbine40. Also, the flow of mixture through conduit or line340may occur when gas turbine40is on-line with mixture flowing with combustion gas35to gas turbine40. Wash controller380then may turn pumps220,230off once the predetermined volume of detergent/water mixture390has been injected into valves61of combustor25. Wash controller380may again activate water pump220to provide a water rinse, if requested. A volume of water120in a rinse may vary. Wash system100can provide improved cleaning and application of anti-static solution160throughout combustor25including through valves61to be fed to gas turbine40, including washing and treating, for example, stage one and two nozzles (S1N)(S2N) and associated wheel space cavities. The increased coverage of anti-static solution160may enhance the ability to suppress the electrostatic attraction of material on the gas turbine blades as well as the stationary nozzles with a reduced propensity to form deposits, such as ash contaminants. Anti-static coverage may provide water wash recovered gas turbine operational gains for a longer period of time. Accordingly, gas turbine engine system10may have improved sustainable performance characteristics. Moreover, wash system100uses existing LLI (axial fuel staging) piping of combustor25such that reconstruction or retrofitting is not required. Wash system100also may provide the ability to control an injection rate and quantity of anti-static solution160to ensure adequate coverage to gas turbine40and including stage one and two nozzles (S1N and S2N) and associated wheel space cavities. Wash controller380may vary the ratio and volume of a detergent/water mixture and/or anti-static solution/water mixture that may be delivered to combustor25. Embodiments of the disclosure may provide off-line cleaning of combustor25, gas turbine40, and especially stage one and two nozzles (S1N and S2N) and associated wheel space cavities of gas turbine40. With reference toFIG.6, where like reference numerals refer to like elements, and a further discussion of those elements is omitted for clarity and brevity, a schematic illustration of a gas turbine engine system10is illustrated with a wash system100. Off-line cleaning as embodied by the disclosure provides anti-oxidant cleaning to stage one and two nozzles (S1N and S2N) and associated wheel space cavities of gas turbine40. Wash system100provides a mixture of demineralized/deionized water and at least one of magnesium (Mg), yttrium (Y) for vanadium mitigation, as described here, or detergent from wash system100injected into combustor25through late lean injection (axial fuel staging) valves61. Moreover, water and at least one of magnesium (Mg), yttrium (Y), or detergent from wash system100can be delivered to the off-line gas turbine engine system10as a foam or water, for example, in a homogeneous stream at late lean injector valves61. In aspects of the embodiments, anti-oxidant cleaner, water and magnesium, is provided for targeted stage one and two nozzles (S1N and S2N) and associated wheel space cavities in situ cleaning in gas turbine40. Wash system100and the associated process use existing LLI (axial fuel staging) valves61to dispense a predetermined mixture of demineralized water and magnesium into combustor25. As embodied by the disclosure, wash system100, when applied to a gas turbine engine system10can: remove vanadium, including vanadium in ash form, from a stage one and stage two nozzle (S1N) and (S2N) and associated wheel space cavities and/or other internal components of gas turbine40; enhance the ability to retain recovered performance of gas turbine engine system10for longer durations after cleaning; mitigate against nozzle plugging and rust formation/oxidation in gas turbine engine system10and especially in gas turbine40; clean and remove ash formations; clean and remove oxidation and particulate from combustor surfaces; provide increased plant reliability and efficiency that is attributable to reduction in cooling air path plugging; and improve reliability of gas turbine engine systems operating on heavy fuel oils. With reference toFIGS.4-7, wash system100provides wash materials to combustor25and then to stage one and two nozzles (S1N and S2N) and associated wheel space cavities for in situ cleaning in gas turbine40when gas turbine engine system10is offline. It is to be noted that compressor washing through providing wash materials at the bellmouth75(FIG.2) of compressor15(FIG.1) may still be provided with any operation and aspect described herein, as embodied by the disclosure. However, the exact system, process, and other details with respect to compressor washing are not germane to aspects of the embodiments, and further discussion will be omitted. Conduit or line190extends from water supply120and line250extends from supply160(such as a chemical supply of, for example, a water-based magnesium sulphite), and lines190and250meet at mixing chamber170. From mixing chamber170, line340extends to combustor25. Line340may include at least one of chemical sensor341for detecting chemical characteristics of mixture, flow senor342, modulating or control valve343, temperature sensor344, and filter345. Each of at least one of chemical sensor341, flow senor342, modulating valve343, temperature sensor344, as well as motor220and chemical source150level sensor162, communicate with controller380. Accordingly, controller380may regulate and manage operation of wash system100in its off-line operation in accordance with the embodiments herein. Another aspect of the embodiments provides cleaning of combustor25, gas turbine40, and in particular stage one and stage two nozzles (S1N) and (S2N) and associated wheelspace cavities of gas turbine40and additionally ash formation mitigation, during operation of gas turbine engine system10. Reference can again be made toFIGS.4-6, wash system100provides wash materials to combustor25and then stage one and two nozzles (S1N and S2N) and associated wheel space cavities for in situ cleaning in gas turbine40, and also provides ash formation mitigation materials to gas turbine engine system10during operation of gas turbine engine system10. As embodied by the disclosure, this aspect of the wash system100provides and distributes low temperature ash formation mitigants with wash materials from combustor25and its late lean injection valves or nozzles61, and then to gas turbine40internal components, including stage one and two nozzles (S1N and S2N) and associated wheel space cavities of gas turbine40. Wash system100, as per this aspect of the embodiments, provides a mixture of demineralized/deionized water from wash system100injected into combustor25through late lean injection (axial fuel staging) valves61. Also, wash system100may also provide yttrium, magnesium or any now known or later developed low temperature ash formation mitigant, in sources130and/or150from wash system100into existing late lean injection (axial fuel staging) valves or nozzles61of combustor25. Non-limiting types of low temperature ash formation mitigant may include water or oil based yttrium or magnesium. As noted herein, wash system100provides wash water, such as demineralized/deionized water, and low temperature ash formation mitigant into combustor25LLI (axial fuel staging) valves61. As embodied by the disclosure, the late lean injection (axial fuel staging) valves61are ahead of stage one and two nozzles (S1N) and (S2N) and associated wheel space cavities in gas turbine40and flow of combustion gases35is in turn delivered to gas turbine40. Low temperature ash formation mitigant delivered to LLI (axial fuel staging) valves61is conveyed to internal components of gas turbine40with the flow35of combustion gases. As embodied by the disclosure, method and system for ash formation mitigation and cleaning during operation of gas turbine engine system10can: reduce a rate of ash formation on a gas turbine stage one and two nozzles (S1N and S2N), associated wheel space cavities and other gas turbine internal turbine components; enhance the ability to retain recovered performance of gas turbine engine system10for longer durations after cleaning; mitigate against nozzle plugging, hot corrosion/oxidation, aero shape/profile deformation that may be due to plugging; enhances the ability to meet and exceed degradation guarantee bonus opportunity, especially in gas turbine engines that operate on heavy fuel oxide (HFO) gas turbines and gas turbine units that rely on gas fuel with high concentrations of vanadium and other ash forming impurities; increased plant reliability, output and efficiency that can be attributable to reduction in nozzle effective area and changes to blade aerodynamic profiles; clean and remove ash formations; clean and remove oxidation and particulate from combustor surfaces; and provide increased plant reliability and efficiency that is attributable to reduction in cooling air path plugging. As embodied by the disclosure, wash system100for ash formation mitigation during gas turbine engine system10(FIG.1) operation can be illustrated by the configuration ofFIG.6. Line190extends from water supply110and line250extends from chemical source150, for example, chemical source150in this aspect includes a volume of yttrium, magnesium or another low temperature ash formation mitigant, and lines190and250meet at mixing chamber170. From mixing chamber170, line340extends to combustor25. Line340may include at least one of chemical sensor341, flow senor342, modulating valve343, temperature sensor344, and filter345. Each of at least one of chemical sensor341, flow senor342, modulating valve343, temperature sensor344, as well as motor200, chemical source150level sensor162communicate with controller380. Accordingly, controller380may regulate and mange operation of wash system100in its off-line operation in accordance with the embodiments herein. A further aspect of the embodiments provides off-line cleaning and passivation of combustor25, gas turbine40, and especially stage one and stage two nozzles (S1N) and (S2N) and associated wheel space cavities of gas turbine40. With continued reference toFIGS.6and7, where like reference numerals refer to like elements, and a further discussion of those elements is omitted for clarity and brevity, a schematic illustration of a gas turbine engine system10is illustrated with a wash system100. Off-line cleaning as embodied by the disclosure, provides anti-oxidant cleaning and passivation of combustor25, gas turbine40, and especially stage 1 nozzle of gas turbine40to stage 1 nozzle of gas turbine40. Wash system100provides a mixture of demineralized/deionized water and at least one of a polyamine or magnesium (Mg) from wash system100injected into combustor25through late lean injection (axial fuel staging) valves61. In this aspect of the embodiments, mixture of demineralized/deionized water and at least one of a polyamine or magnesium is provided for targeted stage one and two nozzles (S1N and S2N) and associated wheel space cavities in situ cleaning in gas turbine40, including stage one and two nozzles (S1N and S2N) and associated wheel space cavities of gas turbine40, when gas turbine40is off-line. Wash system100and the associated process use existing late lean injection (axial fuel staging) valves61to dispense a predetermined mixture of demineralized/deionized water and at least one of a polyamine or magnesium into combustor25, from where predetermined mixture of demineralized water and magnesium can flow into gas turbine40. As embodied by the disclosure, wash system100ofFIG.6, when applied to a gas turbine engine system10can coat internal gas turbine components to passivate them. Included in the internal gas turbine components that are coated and passivated are stage one and stage two nozzles (S1N) and (S2N) plus associated wheel space cavities and/or other internal components of gas turbine40. Passivation, as embodied by the disclosure, can: enhance the ability to retain recovered performance of gas turbine engine system10for longer durations after cleaning; mitigate against nozzle plugging and rust formation/oxidation in gas turbine engine system10and especially in gas turbine40; clean and remove ash formations; may reduce severity and frequency to perform degradation based maintenance; clean and remove oxidation and particulate from combustor surfaces; provide increased plant reliability and efficiency that is attributable to reduction in cooling air path plugging; reduce potential crack propagation and surface degradation of stage one and two nozzles (S1N and S2N) and associated wheel space cavities and/or other gas turbine components; and improve reliability gas turbine engines operating on heavy fuel oils. With reference toFIGS.4-7, wash system100provides mixed demineralized/deionized water and at least one of a polyamine or magnesium to combustor25and then for S1N in situ cleaning in gas turbine40when gas turbine engine system10is offline. Being offline means it is to be noted that compressor washing through providing wash materials at the bellmouth75(FIG.2) of compressor15(FIG.1) may still be provided with any operation and aspect described herein, as embodied by the disclosure. However, the exact system, process, and other details with respect to compressor washing are not germane to aspects of the embodiments, and further discussion will be omitted. Line190extends from water supply110and line250extends from chemical supply150, for example, a mixture of demineralized/deionized water and at least one of a polyamine or magnesium, and lines190and250meet at mixing chamber170. From mixing chamber170, line340extends to combustor25. Line340may include at least one of chemical sensor341, flow senor342, modulating valve343, temperature sensor344, and filter345. Each of at least one of chemical sensor341, flow senor342, modulating valve343, temperature sensor344, as well as motor200and chemical source150level sensor162communicate with controller380. Accordingly, controller380may regulate and mange operation of wash system100in its off-line operation in accordance with the embodiments herein. As embodied by the disclosure, the passivation material, for example but not limited to at least one of a polyamine or magnesium, can be provided in a liquid form or a foam form. Aspects of the disclosure enable the mixture of demineralized/deionized water and at least one of a polyamine or magnesium to flow from late lean injection valves or nozzles to stage one and two nozzles (S1N and S2N) and associated wheel space cavities of gas turbine40for passivation of stage one and two nozzles (S1N and S2N) and associated wheel space cavities, and other internal gas turbine components. An anti-corrosion mixture, as embodied by the disclosure, can include an anti-corrosion agent and water. Anti-corrosion mixture can be supplied as an aqueous solution (e.g., using water as a liquid carrier) to combustor25and then to gas turbine40sections of gas turbine engine system10. Anti-corrosion mixture can coat gas turbine engine components therein with a metal passivation coating which mitigates corrosion on those coated parts. Magnesium sulfate can be used as a cleaning agent, in accordance with certain aspects of the embodiments. For applications in which gas turbine engine system10employs heavy oil as a fuel, heavy oil can be treated with a vanadium-based corrosion/deposit inhibitor. A vanadium-based corrosion/deposit inhibitor can form slag in gas turbine engine system10during operation. Magnesium sulfate may prevent formation of vanadium-based slag promoted by the use of crude, heavy oils as a gas turbine fuel. Magnesium sulfate, as a vanadium-based corrosion/deposit inhibitor, can be connected to a water-based magnesium sulfate solution, in certain aspects of the embodiments. As embodied by the disclosure, anti-corrosion mixture can be pre-mixed (in mixing chamber170) and supplied to gas turbine engine system10. Further, anti-corrosion mixture can be provided to combustor25through washing system100. Anti-corrosion mixture imparts corrosion resistance and/or inhibition to gas turbine engine system10and gas turbine40including its stage one and stage two nozzles (S1N) and (S2N) and associated wheel space cavities by metal passivation. Metal passivation provides an anti-corrosion coating on the metal and/or metal alloy substrates in gas turbine engine system10with which the anti-corrosion mixture, as embodied by the disclosure, comes into contact via entry at late lean injection valves61of combustor25, as discussed above. A resultant anti-corrosion coating therefore (partially or fully) coats gas turbine40especially its stage one nozzles, and various metallic hot gas path components, such as gas turbine blades and other nozzles). Metal passivation imparts a protective shield to metal and/or metal alloy substrates from environmental factors, such as but not limited to, high temperatures, combustion by-products, debris, etc. exhibited in gas turbine engines by forming a metal oxide layer/coating. Metal oxide layer/coating protects metal or metal alloy substrate components of gas turbine40from corrosive species. Anti-corrosion coatings can be seen as a molecular layer, or on other words, a micro coating. In one aspect of the disclosure, anti-corrosion coating also strengthens bonds in the metal or metal alloy substrate of gas turbine engine system10. In another aspect of the embodiments, significant thermal decomposition of anti-corrosion coating may be avoided at temperatures below 500° C. In yet another aspect, successive anti-corrosion treatment cycles can be applied to the gas turbine engine system10using the wash system100described herein, resulting in a multi-layer anti-corrosion coating. Anti-corrosion mixtures can include water and an anti-corrosion agent in a particularly selected, predetermined ratio. Any anti-corrosion agent/inhibitor that is suitable to impart an anti-corrosion coating may be employed. In an embodiment, the anti-corrosion agent is an organic amine. Amine as a corrosion agent/inhibitor by absorbing at the metal/metal oxide surface of components in gas turbine engine system10, thereby restricting access of potentially corrosive species (e.g., dissolved oxygen, carbonic acid, chloride/sulfate anions, etc.) at a metal or metal alloy substrate surface of the gas turbine engine system10component. In another embodiment, the anti-corrosion agent/inhibitor can be two or more organic amines. In yet another embodiment, anti-corrosion agent/inhibitor may be a polyamine. As used herein, the term “polyamine” refers to an organic compound having two or more primary amino groups, NH2. In still another embodiment, the anti-corrosion agent/inhibitor further includes a volatile neutralizing amine, which can neutralize acidic contaminants and elevate pH into an alkaline range, and with which protective metal oxide coatings are particularly stable and adherent. In another aspect of the embodiments, non-limiting examples of the anti-corrosion agent/inhibitor include, but are not limited to, cycloheaxylamine, morpholine, monoethanolamine, N-9-Octadecenyl-1,3-propanediamine, 9-octadecen-1-amine, (Z)-1-5, dimethylaminepropylamine (DMPA), diethylaminoethanol (DEAE), and the like, and combinations thereof. In a further embodiment, an amount of the anti-corrosion agent/inhibitor in the anti-corrosion mixture is from 5 parts per million (ppm) to 1000 ppm. In another embodiment, an amount of the anti-corrosion agent/inhibitor in the anti-corrosion mixture is provided in a range from about 50 ppm to about 800 ppm. In yet another embodiment, the amount of the anti-corrosion agent/inhibitor in the anti-corrosion mixture is provided in a range from about 100 ppm to about 500 ppm. In a particular aspect of the embodiments, the amount of the anti-corrosion agent/inhibitor in a first anti-corrosion mixture supplied to late lean injection valves61of combustor25is from 5 ppm to 1000 ppm. Anti-corrosion mixtures including water and anti-corrosion agent/inhibitor are introduced into gas turbine engine system10via the LLI valves61, as discussed above, are in an aqueous solution. As used herein, “aqueous solution” refers to a liquid phase medium. In an embodiment of the disclosure, the aqueous solution is a liquid phase medium, which is devoid of polyamine gas, water vapor (such as steam), and/or air. Water acts as a liquid carrier for anti-corrosion agent/inhibitor, which is also in a liquid phase. Water thus carries anti-corrosion agent/inhibitor through piping340and into selected regions of combustor25and gas turbine40, coating the components therein with the anti-corrosion coating. As will be appreciated by one skilled in the art, controller80and controller380, as embodied by the disclosure, may be embodied as a system, method or computer program product. Accordingly, controller80and controller380, as embodied by the disclosure, may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, controller80and controller380, as embodied by the disclosure, may take the form of a computer program product embodied in any tangible medium of expression having computer-usable program code embodied in the medium. Additionally, controller80and controller380, as embodied by the disclosure, may take the form of a non-transitory computer readable storage medium storing code representative of a component according to embodiments of the disclosure. FIGS.7-9are flow diagrams or flow charts for processes, as embodied by the disclosure. Like steps in each flow chart are represented by like reference step numbers. With respect toFIG.7, the wash process500is an off-line process500. In step501, gas turbine engine system10is off-line. Optional process502is to wash compressor15, where the compressor wash can be accomplished through known systems, either separate from wash system100as embodied by the disclosure, or in conjunction with wash system100, as embodied by the disclosure. In off-line process500, water and the particular cleansing agent are applied to internal components of gas turbine40through late lean injectors60of combustor25. In process500, water and an anti-oxidation agent are applied at step503and are applied to internal components of gas turbine40through late lean injectors60of combustor25. Process504is optional and can apply a rinse and apply detergent to remove contaminants, such as but not limited to slag, ash, oils, and the like, as needed, and can be applied to internal components of gas turbine40through late lean injectors60of combustor25. Process505is also optional and can apply a rinse, if needed, are applied to internal components of gas turbine40through late lean injectors60of combustor25. In process500, another optional process506can apply a passivation treatment (similar to that applied in process700described hereinafter), to internal components of gas turbine40through late lean injectors60of combustor25. Drying at process507of gas turbine engine system10components can occur for one embodiment of process500. As shown inFIG.8, process600is an on-line wash process. In process601, the gas turbine engine system10(FIG.1) is on-line, and an optional step of washing compressor15may occur in process602. In process603, water and anti-corrosion agent(s) can be applied to internal components of gas turbine40through LLI(s)60of combustor25. As embodied by the disclosure, magnesium or yttrium can be included as the anti-corrosion agent to remove vanadium. Moreover, in process603the water and anti-corrosion agent can be applied as a homogeneous liquid blend or a foam. In process604, a rinse and detergent can be optionally applied to remove contaminants, such as but not limited to slag, ash, oils, and the like, as needed, and can be applied to internal components of gas turbine40through late lean injectors60of combustor25. Process605is an optional application of a rinse, if needed, applied to internal components of gas turbine40through late lean injectors60of combustor25. Process606is also an optional application of an anti-corrosive or passivation treatment. Referring toFIG.9, in off-line wash process700, water and the particular agent are applied to internal components of gas turbine40through late lean injectors60of combustor25. In process701, gas turbine engine system10is off-line. Optional process702is to wash compressor15, where the compressor wash can be accomplished through known systems, either separate from wash system100as embodied by the disclosure, or in conjunction with wash system100, as embodied by the disclosure. In process700, water and an anti-corrosive/passivation treatment-agent are added at process703and are applied to internal components of gas turbine40through late lean injectors60of combustor25. Process704is optional and can apply a rinse and apply detergent to remove contaminants, such as but not limited to slag, ash, oils, and the like, as needed, and can be applied to internal components of gas turbine40through late lean injectors60of combustor25. Process705is optional and can apply a rinse, if needed, applied to internal components of gas turbine40through LLI(s)60of combustor25. Drying at process706of gas turbine engine system10components can occur for off line process700. Any combination of one or more computer usable or computer readable medium/media may be used for controller(s)80and380. The computer-usable or computer-readable medium that may be utilized for controller(s)80and380may include, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More specific examples (a non-exhaustive list) of the computer-readable medium that may be utilized for one or both of controllers80and180would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a transmission media such as those supporting the Internet or an intranet, or a magnetic storage device. Note that the computer-usable or computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted, or otherwise processed in a suitable manner, if necessary, and then stored in a computer memory. In the context of this document, a computer-usable or computer-readable medium may be any medium that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer-usable medium may include a propagated data signal with the computer-usable program code embodied therewith, either in baseband or as part of a carrier wave. The computer usable program code may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc. Computer program code for carrying out wash operations, as embodied by the disclosure, may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). The embodiments are described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer program instructions may also be stored in a computer-readable medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instruction means which implement the function/act specified in the flowchart and/or block diagram block or blocks. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. The foregoing drawings show some of the processing associated according to several embodiments of this disclosure. In this regard, each drawing or block within a flow diagram of the drawings represents a process associated with embodiments of the method described. It should also be noted that in some alternative implementations, the acts noted in the drawings or blocks may occur out of the order noted in the figure or, for example, may in fact be executed substantially concurrently or in the reverse order, depending upon the act involved. Also, one of ordinary skill in the art will recognize that additional blocks that describe the processing may be added. Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged; such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. “Approximately,” as applied to a particular value of a range, applies to both end values and, unless otherwise dependent on the precision of the instrument measuring the value, may indicate +/−10% of the stated value(s). The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The embodiment was chosen and described in order to explain the principles of the disclosure and the practical application and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated. | 62,134 |
11859534 | DETAILED DESCRIPTION Referring toFIG.1, an aircraft100turbojet10is schematically represented and defined as follows: The pod12is used as the outer casing for the various components, including, at the front (left inFIG.1), an upstream fan14(AM). Downstream (AV) of the fan14, the airflow (locally schematised in38inFIG.4) is separated by the separator slat16of an annular wall160into a primary airflow and a secondary airflow. The primary airflow flows through an internal annular air passage or primary jet18when entering the low-pressure compressor22at the intake guide vanes24IGV, also called first vanes. The secondary airflow is diverted by the separator slat16into an external annular air passage20(secondary jet) towards the outlet guide vanes26OGV, also called secondary vanes, and then towards the engine outlet. InFIG.2, we can visualize more precisely the front part161of the separator slat16, which includes the leading edge164located furthest upstream and at which the outer wall162of the separator slat16meets the inner wall163of the separator slat16, the upper wall162forming the inner shell of the secondary jet20. In the present text, axial refers to anything extending along or parallel to the longitudinal axis (X) of rotation of the concerned part of the turbomachine, the axis being in principle the main axis of rotation of the turbomachine. Anything radial (axis Z) and circumferential is that which extends radially to the X axis and around it, respectively. All that is radially with respect to the X axis is internal or inner and external or outer. Thus, the inner wall163is the radially inner wall of the separator slat16. Moreover, any references to upstream and downstream are to be considered in connection with the flow of gases in the (part of the) turbine engine under consideration: these gases enter upstream and exit downstream, generally circulating parallel to the aforementioned longitudinal axis of rotation. In addition, the attached drawings, and the descriptions relating to them, have been defined with reference to the conventional orthogonal reference mark X-Y-Z, with the X axis as defined above. The separator slat16is hollow: the outer face of the wall162serving as the radially inner boundary to the outer annular air passage20receiving the secondary flow while the inner face of the wall163serves as the radially outer boundary to the inner annular air passage18receiving the primary flow. The lower wall163of the separator slat16forms the outer shell of the low-pressure compressor22. Although the axial offset (X) downstream of the IGVs24from the leading edge164of the separator slat16is less than that of the OGVs26from the same leading edge164, the portion of the front part161directly adjacent to the leading edge164of the separator slat16is clear. For the induced effect of aero-acoustic management by limiting the noise generated by this area, this leading edge164can therefore be expected to have a serrated profile lineline28with a succession of teeth30and depressions32, as shown in the examples inFIGS.5-11, for example. But structures other than on a turbomachine, such as the turbojet10, may be affected by the solution of the invention and therefore have a leading edge164with a profile line28showing serrations including a succession of teeth30and depressions32. FIG.9shows an aircraft100on which profiled structures with such a serrated profile line28are present, on the leading edge, on the wings39, on a pylon41supporting an engine43of the aircraft, on a fin44, a stabilizer46, a propeller or blade48of an open rotor. Furthermore,FIG.3shows a localized serrated profile line28on what may be identified as50, a helicopter blade, a fan blade, of the rotor or the rectifier, a leading edge slat or an aircraft wing flap. All these aerodynamic profiles have in common that they generate a boundary layer on the downstream surface, and therefore a turbulent flow. Whatever the application, for the serrated profile line28, we will consider that it presents undulations that define:along a direction (L) of elongation of the leading edge164, an elementary geometry which repeats itself, two identical (or quasi-identical, when two consecutive teeth have small variations in geometry, to +/−25%) undulations of two successive elementary geometries, such as34,36FIGS.5-6, along said direction L having between them, in this direction, a distance, λ (in m), anda maximum amplitude, h (in m), perpendicular to this direction L. The maximum amplitude h is defined as the maximum distance, along the perpendicular to this direction L, between the top—the most prominent if any—of teeth30and the bottom of the depressions32—the deepest if any—, as shown inFIG.5under the assumption of an elementary geometry with several, preferably two undulations—two different teeth30and two different depressions32. It is also specified that:the direction L is the direction along which the leading edge line164aextends, which can be confused with the leading edge164when viewed along its entire length. This direction L can be straight (e.g. in the case of a wing, daggerboard, stabiliser), or curved, or even closed in on itself (possible case of a propeller, fan blade, rotor or rectifier blade, or the separator slat16),the direction of the maximum amplitude, h, may typically be parallel to the general X axis (FIG.2,FIG.9in part); but it may also be oriented in another direction, for example in the case of a helicopter blade (in which case the direction is a priori perpendicular to the Z axis). In accordance with the invention, in order to attenuate locally intense pressure fluctuations, at least one porous, acoustically absorbent region52is provided on the profile structure concerned, which is located towards the bottom of the depressions32. Thus, these porous acoustically absorbent regions52form locally bottoms for the depressions32and thus define, with the parts of the body62of the profile structure they occupy, the serrated profile line at the leading edge and/or the trailing edge of said profile structure. As usual in this field, the body62still provides the coherence, the essential shape and the rigidity of the profiled structure and thus essentially defines the profiled structure, as can be seen by way of example in the figures. It was found that to promote this attenuation, it may be preferable that the (geometric) centre of the (each) region52with acoustic treatment or porous surface (whether rectangular, elliptical, or other) be located at a distance d (in m) downstream (AV) from the leading edge of the airfoil164/line164a, at the bottom of the depressions124such that: d=h/10, within 30%. In order to reach most of the region with high pressure fluctuations, it is furthermore proposed that the porous acoustically absorbent region52under consideration should have:in the direction of the leading and/or trailing edge line164a(i.e. In the direction of the wingspan or elongation), two limits separated by a distance a (in m) such that a is equal to one third of said distance between two consecutive tooth tips, to within 30%,in the direction of the chord40, two limits separated by a distance b (in m) such that b=h/3, within 30%. FIGS.10and11show this. We see that the distance d is to be taken parallel to “h”, perpendicular to the direction L (typically at the deepest part of the depression32), and that d=b/2. Lengths a and b are used to dimension the edges of rectangles or other shapes where the surface is acoustically treated. In the area where a is of the order of one third of said distance between two consecutive tooth tips and where the fluctuations in wall pressure have been found to be greatest, the effect of porosity via the acoustically absorbent structure must be effective. The indicated margins of (+/−) 30% are intended to remove technical uncertainties/imprecisions. In the claimed applications, the aim is to obtain a significant reduction in the surface area of the structure/part under consideration, and thus in the aerodynamic losses, compared to what it would have been without the solution of the invention, thus having an effect on broadband noise reduction. The porous surface or acoustic treatment targets the place where the interaction noise with wake turbulence is generated. Thus, a major contribution is considered to be that of optimising the surface to be treated in order to reduce acoustic levels. In relation to the example inFIG.5, where the elementary geometry is multi-corrugated, two in the example, the distance λ following the direction L is supplemented by other distances following the same direction L, here two, λ1, λ2, relating to the distances between two consecutive vertices of different but successive teeth30. In accordance with the above-mentioned preferred rules, it will be considered preferable here, for the reasons already indicated, that: a=λ1/3 or a=λ2/3 (within 30%), whichever is the greater distance, so here we will prefer a=λ1/3 (within 30%). From a practical point of view, several technical solutions with an impact on the surface of the structure in the acoustically treated region52can be foreseen. Two of them have been chosen to reconcile effectiveness in reducing the acoustic response at the level of the depressions32and technical mastery, including in terms of maintenance. In the solution shown inFIG.12, the porous acoustically absorbent region52comprises a porous foam54, which may be metallic, having pores of cross-section (in m) less than said distance a/4 or b/4. An alternative is that the pores should be less than 1/10 mm in section. The porous foam54is present on the surface (outer)56towards said profiled leading edge164—where it could then define the shape of the profile—and may occupy a significant part of the thickness of the profiled structure, or even all of this thickness, as shown in the figure. In order to hold this mass of foam, it can be expected to have a protruding tooth shape58towards the downstream (AV), fixed, for example glued, in a frontal depression60of the body62of the structure, which could for example be the pylon41. One or more bars64could furthermore anchor the foam mass with its tooth58in the body62. In the solution shown inFIG.13, the porous acoustically absorbent region52comprises, on the surface56of the profiled structure, a material66with micro-perforated sheet metal or resonant cavities covering a porous foam54having pores with a cross-section (in m) less than a/4 or b/4. An alternative is also that the pores should be less than 1/10 mm in section. A Helmholtz resonator can thus be formed at the location of this porous, acoustically absorbent region52. With both material66and foam54on the surface, a surface finish56compatible with low aerodynamic losses can be achieved. Screws68could secure the fixation of material66in the body62of the structure. In connection withFIGS.14-16, we will now return to the particular case of application to IGV24of the solution of the invention, with its porous acoustically absorbent regions52. In order to benefit from favourable aerodynamics, in particular at the air inlet of the low-pressure compressor22, it is suggested that around the X axis, at least some of the depressions32of the serrated profile lineline28be angularly offset (circumferentially) in relation to the angular position of the IGV blades24, so that these depressions32are interposed between two first IGV blades24circumferentially successive, as shown. In these figures, the IGV24are even placed axially (X) in the continuity of teeth30; more precisely each IGV24has been placed substantially in alignment, along the X axis, with the top of tooth30which precedes it upstream (AM). InFIG.14, this alignment is parallel to the general X axis. And teeth30, which each have a top31, are individually symmetrical there with respect to a parallel to the X axis, this parallel passing through the top31of the tooth30considered (see the parallel X1for example). InFIGS.15-16, the IGV24are inclined in the X-Y plane with respect to the X axis; angle β. The teeth30are, circumferentially around this X axis, each inclined at the same angle β (but this angle could vary), in the same direction as the common IGV24. The influence of the rotation of fan14, which is assumed to rotate in the positive direction of the Y axis, has been taken into account here (seeFIG.1and arrowhead in the L direction inFIG.2). FIG.9, the angle of inclination of the profile28in serrations is marked a to indicate that, especially when not arranged downstream of a fan, the angle θ will not necessarily be respected, but that the angle of inclination α here takes into account the direction of the air flow arriving on the profile28. An angle α, β or even β′ (seeFIG.17below) between 30 and 60°, preferably between 35 and 45°, would be appropriate, given the initial results of tests carried out. This is therefore not limiting. Thus, both the (leading edges of the) IGV24and the (leading edges of the) teeth30are in fact generally facing the air stream38whose overall oblique orientation U is the result of its components Ux following X and Uy following Y, taking into account the here agreed direction of rotation of fan14. Teeth30are individually axially non-symmetrical in relation to a parallel (see X′1and X′2FIGS.10-11) to the general axis X, again through the top31of the tooth in question. The purpose of these positions can be considered to be twofold. First, it is to avoid the interaction between the accelerated and turbulent flow produced in depressions32and the leading edge25of the IGVs (FIGS.14-16). This can indeed contribute significantly to the broadband noise of the low-pressure compressor22. Secondly, this technical solution can be used to optimise the air intake of the low-pressure compressor22and to reduce any aerodynamic losses. As shown inFIGS.15-16, these first blades/IGV24may individually exhibit a line240of average camber along their chord, to account for the influence of fan14rotation. The angle of inclination of the flow produced by fan14depends on the engine speed, i.e. the speed of the fan. Therefore, consideration is being given to orienting teeth30in the direction of the average IGV camber or the camber at the leading edge164. The angle values selected can be averaged along the wingspan or elongation of the IGVs, or take the values of the IGV camber at the blade tip. As illustrated and in this example, the upper surface241is directed in the positive Y direction, the lower surface on the opposite side. In order to further limit the acoustic impact on the IGV24of the swirling air flow that the fan14thus generates downstream, it is also proposed, as shown inFIGS.15-16, that the teeth30be, circumferentially around said general axis X, oriented globally in the direction of a tangent42to said line240of mean camber of the IGV24blades, at the level of their leading edges25. The tangent is at a (β) non-zero angle to the direction of the general axis (X) of the turbomachine. An advantage is then to align the teeth30in the direction of the IGV camber and again to be able to adapt the geometry of the air inlet of compressor22to its environment. The direction of the air flow downstream of fan12depends on its rotation speed, so aligning the teeth in the direction of the IGVs (which are a fixed part) could be a good compromise between variable speeds and geometries to be fixed. It should be noted, however, that the direction of flow upstream of the IGV blades (or the teeth of the separator nozzle16for that matter) will not necessarily be aligned with the camber of the IGVs. Systematically, along the general X axis, in the preferred embodiments shown, teeth30are located upstream from the leading edges2of the IGV24blades, as can be seen in the figures. However, for a dimensional limitation that may exist between the leading edge of the slat and the IGV blades (typically of the order of 1-5 cm), as well as to have the possibility to increase the size/amplitude of the teeth30, it is proposed that, still in this direction of the X axis, the bottoms320of the depressions32of the serrated profile lineline28belong at least for some of them to a first surface, transverse to said X axis, marked Y1FIG.15and Y2FIG.16, positioned at (FIG.15) or further downstream (AV;FIG.16) than a second surface also transverse to the X axis, marked Y′1FIG.15and Y′2FIG.16, to which belong at least some of the leading edges25of the IGV blades24. In spite of the illustrations, this is a priori independent of the shape of the tops of teeth30and the bottoms320of the depressions32. In this respect, the teeth30and depressions32of the serrated profile lineline28will individually present a wavy shape, with rounded tops (FIG.15) or sharp tops (FIG.16), in order to promote effective noise reduction by minimising the mechanical stresses supported by this geometry. As for the shape of the side walls, marked300inFIG.16of these teeth30and depressions32, they can be individually and locally presented as straight (FIG.16), in order to favour the decorrelation of the noise sources along the leading edge and to facilitate the manufacture of this geometry. We will now come back to the inclination of the airfoil structure, in the case of a structure having, in the direction of its leading edge line164a, opposite ends70a,70b, and thus a kind of span (like the length of the wing or that of the pylon41), even if one (at least) of these ends is a root, as on a wing, see example inFIG.9where the considered structure is—substantially—linear along the Y-axis. In such cases (wings, blades, propellers, pylon, dagger boards . . . ) it should be noted that the inclinations of the teeth30will be favourably oriented each and all towards one of these ends (called second end), whether it is, for example for a wing, the root70aor the free end70b. In the case of “wingspan” profiled structures, the angle a will be located in the general plane of the structure, such as plane P which contains the X-Y axes for the wings39inFIG.9. It is also possible that the inclinations of teeth30may vary along the span/elongation (direction L). It should also be noted that the above comments in relation to the figures only refer to leading edge situations. However, trailing edges could be concerned, alternatively or in addition, such as (lines of) trailing edges164bwith profile28in wing serrations, as shown inFIG.9, other turbomachine or aircraft structures provided with trailing edges could also be concerned by the invention. As a trailing edge on an annular wall, there is a nozzle at the outlet of the primary and secondary jets. At the trailing edge, the noise source can typically be related to the interaction between turbulence in the boundary layer of the profile and this trailing edge. InFIG.17, a situation has also been schematised in which, since the turbomachine is always with an upstream fan (14above) and has a general axis (X) around which this upstream fan can rotate, the teeth30are, circumferentially around the general axis (X), individually inclined (angle β′) in the direction of the mean camber of the first IGV24blades. It can also be noted that, inFIG.15, the teeth30are also individually inclined circumferentially around the X-axis in the direction of the camber of the IGV blades at their leading edges25. This angle, marked β, of the teeth30will be identical or not to the angle α of the velocity vector U1which marks the general direction of the flow downstream of the fan. On the attached figures, it will have been understood that those where a velocity vector (U, U1, . . . ) is shown upstream of the leading edge illustrate cases where the teeth are oriented towards the direction of the flow. | 19,833 |
11859535 | DETAILED DESCRIPTION FIG.1schematically illustrates an assembly20for an engine such as a gas turbine engine with at least one flowpath22; e.g., a core flowpath, a gas path, etc. This turbine engine assembly20includes a fuel source24and at least one fuel-cooled engine component26. The flowpath22may include one or more (e.g., serially arranged) fluidly coupled passages, chambers, plenums and/or any other internal volumes that collectively form a pathway for fluid flow (e.g., gas flow) within the turbine engine. The flowpath22may extend within and/or through any one or more sections of the turbine engine. The flowpath22may include, for example: a passage within a compressor section of the turbine engine; a pre-diffuser passage, a diffuser plenum and/or a combustion chamber within a combustor section of the turbine engine; and a passage within a turbine section of the turbine engine. The flowpath22may also include a passage within a fan section of the turbine engine, a passage within an exhaust section of the turbine engine and/or a passage in a supplemental thrust section (e.g., an augmentor section) of the turbine engine. The present disclosure, however, is not limited to the foregoing exemplary flowpath configurations. The fuel source24is configured to provide fuel to the engine component26during turbine engine operation. The fuel source24may also be configured to store the fuel during turbine engine operation and/or while the turbine engine is non-operational (e.g., before and/or after turbine engine operation). The fuel stored and/or provided by the fuel source24may be a non-hydrocarbon fuel (e.g., hydrocarbon-free fuel) and/or a non-coking fuel. The fuel, for example, may be or otherwise include ammonia (e.g., liquid or gaseous NH3), hydrogen (e.g., liquid or gaseous H2) or any other combustible composition that includes, for example, hydrogen (H). The present disclosure, however, is not limited to the foregoing exemplary fuels. The fuel source24ofFIG.1includes a fuel reservoir28and a fuel regulator30. The fuel reservoir28may be configured as or otherwise include a container; e.g., a tank, a cylinder, a pressure vessel, a bladder, etc. The fuel reservoir28is configured to contain and hold a quantity of the fuel. The fuel regulator30may be configured as or otherwise include a pump and/or a valve. The fuel regulator30is configured to control flow of the fuel from the fuel reservoir28to one or more downstream components of the turbine engine. The fuel regulator30ofFIG.1, for example, directs (e.g., pumps) the fuel out from the fuel reservoir28to at least the downstream engine component26. The engine component26may be, may include or may be part of any cooled component or structure in the turbine engine. This engine component26may be arranged adjacent or otherwise proximate the flowpath22within the turbine engine. The engine component26, for example, may be configured to form a peripheral boundary32of the flowpath22(e.g., one or more surfaces forming the flowpath22) within the turbine engine; e.g., seeFIGS.2and3. Examples of the engine component26include, but are not limited to, an airfoil, a vane (e.g., a turbine vane), a strut, a blade outer air seal (BOAS) and a flowpath wall. Examples of the flowpath wall may include, but are not limited to, a combustor wall, a diffuser case, an exhaust liner, a platform and a shroud. The present disclosure, however, is not limited to the foregoing exemplary engine component configurations. During turbine engine operation, the engine component26may be exposed to relatively high temperature gases flowing through the flowpath22and/or relatively high heat fluxes associated with (e.g., produced by) the flowpath gases. To prevent or reduce effects of thermally induced material degradation and/or thermally induced internal stresses to the engine component26, the engine component26includes at least one internal passage34; e.g., an internal cooling passage. This internal passage34extends within (e.g., through) the engine component26, and is fluidly coupled with the fuel source24. The engine component26is thereby configured to receive the fuel from the fuel source24(e.g., the fuel reservoir28via the fuel regulator30), and direct the fuel within/through the internal passage34for cooling the engine component26. During cooling of the engine component26, heat energy may transfer from material of the engine component26to the fuel within the internal passage34through conduction and/or convection. This heat energy transfer reduces the heat energy in the engine component26and thereby reduces the temperature of (e.g., cools) the engine component26, while increasing the energy of the fuel within the internal passage34. The flux of energy into the fuel may be associated with one or more processes such as, but not limited to, (1) a temperature change of the fuel, (2) phase change of the fuel and (3) cracking (e.g., decomposition) of the fuel. The fuel may enter the engine component26and, for example, its internal passage34in a liquid phase (e.g., liquid NH3, etc.). The flux of energy into this liquid fuel may increase the temperature of the fuel; e.g., heat the fuel. When the temperature of the liquid fuel reaches a first temperature (e.g., a vaporization temperature), the flux of energy into the liquid fuel may cause at least some (or all) of the fuel to vaporize into vaporized fuel (e.g., gaseous NH3, etc.). The flux of energy into the vaporized fuel may further increase the temperature of the fuel. When the temperature of the vaporized fuel reaches a second temperature (e.g., a cracking temperature), the flux of energy into the vaporized fuel may cause at least some (or all) of the fuel to crack (e.g., decompose), for example via an endothermic reaction, into at least partially (or completely) cracked fuel (e.g., gaseous H2and gaseous N2, etc.). By facilitating the foregoing processes, the turbine engine assembly20is operable to increase heat transfer between the engine component26and the fuel and, thus, provide enhance engine component cooling. By contrast, if the fuel was only heated and/or vaporized for example, the flux of energy from the engine component26to the fuel may be limited. To aid and/or facilitate in the fuel cracking process, the engine component26may be constructed from a catalytic material36. Alternatively, at least a portion or all of the internal passage34may be lined with the catalytic material36. For example, the engine component26may include a catalytic liner for the internal passage34. In another example, a wall of the internal passage34may be lined with a catalytic coating. Examples of the catalytic material36may include, but are not limited to, nickel (Ni), iron (Fe), ruthenium (Ru) and platinum (Pt). The present disclosure, however, is not limited to the foregoing exemplary catalytic materials. The turbine engine assembly20ofFIG.1is configured to direct at least some or all of the fuel used for cooling the engine component26(e.g., the at least partially or completely cracked fuel) into the flowpath22for combustion. For example, referring toFIG.2, the turbine engine assembly20may also include one or more fuel injectors37(one shown inFIG.2for ease of illustration). Each of these fuel injectors37may be configured to receive the fuel used for cooling the engine component26(e.g., the at least partially or completely cracked fuel) from the engine component26, and direct (e.g., inject) that fuel into the flowpath22(e.g., the combustion chamber, an exhaust duct and/or an augmentor duct) for combustion. In another example, referring toFIG.3, the engine component26may include one or more perforations40; e.g., through-holes, nozzle orifices, fuel injection orifices, etc. These perforations40may fluidly couple the internal passage34with the flowpath22(e.g., the combustion chamber, the exhaust duct and/or the augmentor duct). The perforations40may thereby direct (e.g., inject) at least some of the partially or completely cracked fuel into the flowpath22for combustion. Such perforations40may also facilitate staged combustion within the flowpath22. By using the fuel for at least dual purposes to cool the engine component26and then combusting that fuel within the flowpath22, the turbine engine assembly20may increase turbine engine efficiency. In particular, since the heat energy removed from the engine component26for cooling is at least partially captured by the fuel and that fuel is then directed back into the flowpath22for combustion, at least some of the heat energy that originally heats the engine component26is returned to the flowpath22for conversion into work. Enthalpy that is removed from the flowpath22via heating the engine component26and then removed from the engine component26via the cooling process may thereby be at least partially reintroduced into the flowpath22by the coolant fuel which is subsequently burned. By contrast, air cooling an engine component may decrease turbine engine efficiency since a portion of air that would otherwise be used for combustion is repurposed for cooling. Furthermore, air cooling may reduce flowpath temperature (e.g., by directing relatively cool air into a relatively hot gas flow) and, thus, reduce the work potential of the turbine engine. Directing the coolant fuel (e.g., the at least partially or completely cracked fuel such as a combination of gaseous H2and gaseous N2, or a combination of gaseous H2, gaseous N2and gaseous NH3) into the flowpath22for combustion may significantly increase the volumetric flow rate within the flowpath22as compared to, for example, directing traditional hydrocarbon fuel. The N2, that was originally bound in the fuel and elevated in pressure by pumping a liquid rather than compressing a gas, increases the power output for a given energy input compared to a hydrocarbon fuel. Alternatively, for a desired fixed power output, using the coolant fuel may reduce compression design requirements of the compressor section. In addition to the foregoing, directing the at least partially (e.g., 50%, 60%, 70%, 80% or more) cracked fuel into the flowpath22for combustion may have benefits over directing (e.g., 50%, 60%, 70%, 80% or more) uncracked fuel into the flowpath22for combustion. For example, gaseous H2may be easier to combust within the flowpath22than vaporized (non-cracked) NH3. Using an alternative (e.g., non-hydrocarbon) fuel such as NH3can provide various benefits in addition to those discussed above. For example, NH3can be heated to a relatively high temperature without significant negative effects. Thus, NH3can be used in relatively high temperature environments for cooling prior to combustion as described above. By contrast, in relatively high temperature environments, hydrocarbon fuel such as kerosene (e.g., jet fuel) can coke. Such coking may reduce or block fuel flow and/or otherwise degrade fuel system operation. Hydrocarbon fuel therefore may not be suitable for cooling high temperature components within a turbine engine such as, but not limited to, a combustor wall, a shroud, a blade outer air seal (BOAS), and the like. In some embodiments, referring still toFIG.1, the engine component26may receive the fuel in the liquid phase as described above. In other embodiments, the engine component26may receive the fuel in the gaseous phase. The fuel stored in the fuel reservoir28, for example, may be vaporized fuel. Alternatively, referring toFIG.4, another engine component42(e.g., another fuel-cool component of the turbine engine, or a fuel vaporizer) may be arranged between the fuel source24and the engine component26. The upstream engine component42may be cooled by heating the fuel and vaporizing the fuel. The downstream engine component26may be cooled by heating the vaporized fuel and/or at least partially (or completely) cracking the vaporized fuel. Of course, in other embodiments, each of the engine components26and42may heat, vaporize and/or crack at least some of the fuel flowing therewithin. In some embodiments, referring toFIG.1, the engine component26may be configured to at least partially (or completely) crack the fuel as described above. In other embodiments, however, the engine component26may be configured to heat the fuel and/or vaporize the fuel without, for example, cracking the fuel. In such embodiments, the turbine engine assembly20may direct (e.g., primarily or only uncracked) vaporized fuel (e.g., gaseous NH3, gaseous H2, etc.) into the flowpath22for combustion. In some embodiments, referring toFIGS.5and6, the fuel circuit may be used for cooling and/or heating components and/or internal volumes (e.g., a cabin compartment, etc.) in device(s) or system(s) outside of the turbine engine; e.g., an airframe of an aircraft propelled by and/or powered by the turbine engine. For example, referring toFIG.5, an airframe component44(e.g., a component of a cabin environmental control system such as, but not limited to, a heat exchanger within the airframe) may be fluidly coupled inline between the fuel source24and the engine component26. With such a configuration, the airframe component44may be cooled by the fuel (e.g., functioning as refrigerant) flowing therethrough. Alternatively, referring toFIG.6, the airframe component44may be fluidly coupled inline between the engine component26and the output to the flowpath22. With such a configuration, the airframe component44may be heated by the fuel flowing therethrough. Still alternatively, a valve system may be included to selectively routing the fuel, for example, as shown inFIG.5or as shown inFIG.6depending upon airframe needs; e.g., heat the airframe component44when it is cold outside and cool the airframe component44when it is hot outside. In some embodiments, referring toFIGS.7and8, the fuel may be provided to the engine component26to selectively cool that component. For example, heat transfer associated with heating the liquid fuel may be less than heat transfer associated with heating the vaporized fuel. Therefore, referring toFIG.7, fuel may be directed through the internal passage34such that the fuel is in its liquid phase at (e.g., in, adjacent or proximate) a relatively cold region46of the engine component26, and the fuel is in its gaseous phase at a relatively hot region48of the engine component26. Alternatively, referring toFIG.8, one internal passage34A within the engine component26at the relatively cold region46may receive liquid fuel, whereas another internal passage34B within the engine component26at the relatively hot region48may receive the vaporized fuel. In still other embodiments, a plurality of engine components26A and26B (generally referred to as “26”) that are cooled by the fuel may be staged as shown, for example, inFIG.9. The upstream engine component26A, for example, may receive the liquid fuel and may be relatively cool whereas the downstream engine component26B may receive at least some or all of the vaporized fuel and may be relatively hot. Of course, in other embodiments, each of the engine components26may heat, vaporize and/or crack at least some of the fuel flowing therewithin. FIG.10illustrates the turbine engine assembly20configured with an annular combustor50and a vane structure52; e.g., an inlet turbine nozzle. This combustor50extends axially along an axial centerline54between a forward, upstream end56and an aft, downstream end58, which axial centerline54may be coaxial with a rotational axis of the turbine engine. The combustor50extends circumferentially about (e.g., completely around) the axial centerline54. The combustor50ofFIG.10includes an annular combustor bulkhead60, a tubular combustor inner wall62and a tubular combustor outer wall64. The bulkhead60is arranged at the forward, upstream end56of the combustor50. The bulkhead60extends radially between and is connected to the inner wall62and the outer wall64. The inner wall62is connected to and projects axially out from the bulkhead60to the aft, downstream end58of the combustor50. The inner wall62is positioned radially within the outer wall64. The outer wall64is connected to and projects axially out from the bulkhead60to the aft, downstream end58of the combustor50. The outer wall64extends circumferentially around (e.g., circumscribes) and axially overlaps the inner wall62. The bulkhead60, the inner wall62and the outer wall64may thereby form the combustion chamber66; e.g., an annular combustion chamber. The vane structure52is arranged at the aft, downstream end58of the combustor50. This vane structure52is configured to direct combustion products produced within the combustion chamber66into the turbine section (not visible inFIG.10). The vane structure52ofFIG.10includes a stator vane array, which array includes a plurality of stator turbine vanes68(one visible inFIG.10) arranged circumferentially about the axial centerline54. Any one or more or all of the turbine engine components60,62,64and/or68may each be configured as a fuel-cooled engine component (e.g.,26) as described above. Each of the turbine engine components60,62,64and/or68ofFIG.10, for example, includes at least one respective internal passage70-74for flowing the fuel therethrough. The fuel, for example, may be directed sequentially through the outer wall passage73and the outer bulkhead passage71to the one or more fuel injectors37(one visible inFIG.10) for injection into the combustion chamber66for combustion. The fuel may also be directed (in parallel with the above flow) sequentially through the internal passage74in one or more of the stator vanes68, the inner wall passage72and the inner bulkhead passage70to the one or more fuel injectors37for injection into the combustion chamber66for combustion. Each of the turbine engine components60,62,64and/or68may be configured to heat, vaporize and/or crack at least some of the fuel prior to injection. Alternatively, the turbine engine components60,62,64and/or68may be configured for staged cooling where, for example, an upstream one of the components heats and vaporizes the fuel and a downstream one of the components heats and at least partially cracks the fuel. In some embodiments, any one or more or all of the turbine engine components26(e.g.,60,62,64and/or68) may each be configured without gas (e.g., air) cooling. In other embodiments, referring toFIG.11, any one or more or all of the turbine engine components26(e.g.,60,62,64and/or68) may each be configured with supplemental gas (e.g., air) cooling. The turbine engine component ofFIG.11, for example, includes an additional cooling passage76and/or one or more cooling apertures78(e.g., effusion apertures, impingement apertures, etc.). FIG.12illustrates a portion of the turbine engine assembly20configured with a blade outer air seal80(BOAS) and a first rotor stage82of the turbine section. The blade outer air seal80extends circumferentially around (e.g., circumscribes) the first rotor stage82. The blade outer air seal80is arranged in close proximity to turbine blade tips84(one visible inFIG.12) of the first rotor stage82to reduce or prevent leakage across those tips84during turbine engine operation. The blade outer air seal80may be configured as a fuel-cooled engine component26as described above. An internal passage88(or passages) of the blade outer air seal80, for example, may be fluidly coupled in line with and between the fuel source24and the vane structure52and its vane passages74. In some embodiments, referring toFIG.10, the coolant fuel may be the primary or only fuel directed into the flowpath22(e.g., the combustion chamber66) for combustion. However, in other embodiments, the fuel injector37may also or alternatively receive additional (e.g., non-coolant) fuel. For example, the fuel injector37may also or alternatively receive non-hydrocarbon fuel (e.g., gaseous H2, N2and/or NH3) via another (e.g., bypass) path from the fuel source24or another (e.g., separate) fuel source. The fuel injector37may also or alternatively receive hydrocarbon fuel (e.g., kerosene) from another fuel source. In some embodiments, the flow of fuel used for cooling may be varied based on engine operating conditions, flight conditions and/or environmental conditions. For example, less fuel may be used for cooling where the engine is at a low power setting (e.g., idle) where thermal loads (e.g., cooling requirements) are relatively low. By contrast, more fuel may be used for cooling where the engine is at a high power setting (e.g., aircraft takeoff) where thermal loads (e.g., cooling requirements) are relatively high. FIG.13a side cutaway illustration of a geared turbine engine90with which the turbine engine assemblies20described above can be included. This turbine engine90extends along an axial centerline92(e.g., the centerline54) between an upstream airflow inlet94and a downstream airflow exhaust96. The turbine engine90includes the fan section98, the compressor section99, the combustor section100and the turbine section101. The compressor section99includes a low pressure compressor (LPC) section99A and a high pressure compressor (HPC) section99B. The turbine section101includes a high pressure turbine (HPT) section101A and a low pressure turbine (LPT) section101B. The engine sections98-101are arranged sequentially along the centerline92within an engine housing104. This housing104includes an inner case106(e.g., a core case) and an outer case108(e.g., a fan case). The inner case106may house one or more of the engine sections99A-101B; e.g., an engine core. The outer case108may house at least the fan section98. Each of the engine sections98,99A,99B,101A and101B includes a respective rotor110-114. Each of these rotors110-114includes a plurality of rotor blades arranged circumferentially around and connected to one or more respective rotor disks. The rotor blades, for example, may be formed integral with or mechanically fastened, welded, brazed, adhered and/or otherwise attached to the respective rotor disk(s). The fan rotor110is connected to a gear train115, for example, through a fan shaft116. The gear train115and the LPC rotor111are connected to and driven by the LPT rotor114through a low speed shaft117. The HPC rotor112is connected to and driven by the HPT rotor113through a high speed shaft118. The shafts116-118are rotatably supported by a plurality of bearings120; e.g., rolling element and/or thrust bearings. Each of these bearings120is connected to the engine housing104by at least one stationary structure such as, for example, an annular support strut. During operation, air enters the turbine engine90through the airflow inlet94. This air is directed through the fan section98and into a core gas path122(e.g., the flowpath22) and a bypass gas path124. The core gas path122extends sequentially through the engine sections99A-101B. The air within the core gas path122may be referred to as “core air”. The bypass gas path124extends through a bypass duct, which bypasses the engine core. The air within the bypass gas path124may be referred to as “bypass air”. The core air is compressed by the compressor rotors111and112and directed into the combustion chamber66in the combustor section100. The fuel (e.g., the combination of gaseous H2and gaseous N2, the combination of gaseous H2, gaseous N2and gaseous NH3, etc.) is injected into the combustion chamber66and mixed with the compressed core air to provide a fuel-air mixture. This fuel air mixture is ignited and combustion products thereof flow through and sequentially cause the turbine rotors113and114to rotate. The rotation of the turbine rotors113and114respectively drive rotation of the compressor rotors112and111and, thus, compression of the air received from a core airflow inlet. The rotation of the turbine rotor114also drives rotation of the fan rotor110, which propels bypass air through and out of the bypass gas path124. The propulsion of the bypass air may account for a majority of thrust generated by the turbine engine90ofFIG.13, e.g., more than seventy-five percent (75%) of engine thrust. The turbine engine90of the present disclosure, however, is not limited to the foregoing exemplary thrust ratio. The turbine engine assembly20may be included in various turbine engines other than the one described above. The turbine engine assembly20, for example, may be included in a geared turbine engine where a gear train connects one or more shafts to one or more rotors in a fan section, a compressor section and/or any other engine section. Alternatively, the turbine engine assembly20may be included in a turbine engine configured without a gear train. The turbine engine assembly20may be included in a geared or non-geared turbine engine configured with a single spool, with two spools (e.g., seeFIG.13), or with more than two spools. The turbine engine may be configured as a turbofan engine, a turbojet engine, a propfan engine, a pusher fan engine or any other type of turbine engine. The present disclosure therefore is not limited to any particular types or configurations of turbine engines. The present disclosure is not limited to aircraft thrust applications. The turbine engine, for example, may alternatively be configured as an auxiliary power unit (APU) for the aircraft, a (e.g., industrial) turbine engine for power generation, etc. Furthermore, the present disclosure is not limited to turbine engine applications. For example, in other embodiments, the assembly20may be configured for another type of engine such as, but not limited to, an (e.g., rotary or reciprocating piston) internal combustion (IC) engine, etc. While various embodiments of the present disclosure have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the disclosure. For example, the present disclosure as described herein includes several aspects and embodiments that include particular features. Although these features may be described individually, it is within the scope of the present disclosure that some or all of these features may be combined with any one of the aspects and remain within the scope of the disclosure. Accordingly, the present disclosure is not to be restricted except in light of the attached claims and their equivalents. | 26,351 |
11859536 | DETAILED DESCRIPTION Bleed air produced by a gas turbine engine of an aircraft is compressed air from the compressor stage that is used for various functions of that engine (such as cooling of turbines and to help seal bearing cavities, for example). Bleed air may also be used for aircraft functions (such as engine starting, cabin pressure, air systems, pressurizing liquid tanks, etc.). Engine bleed air can be derived from the high pressure or the low pressure compressor stage, depending on the air pressure requirements and the engine operating condition. In at least some multi-engine aircraft, such as helicopters, prior art bleed systems may not be capable of supplying an adequate flowrate and/or pressure of bleed air in some operating conditions, such as when a gas turbine engine providing the bleed air is operating in a standby mode. For the purposes of this document, the terms “standby” and “sub-idle” are used with respect to a given engine to mean that the given engine is operating but is providing materially no motive power to the aircraft with which it is used, with the “sub-idle” operation being a particular type of standby operation according to the present technology as described in this document. The present technology has been developed in view of this finding, and provides for a secondary compressed air system may provide compressed air to one or more of an aircraft's engines while the engine(s) is/are in a standby or a sub-idle mode. With the development of the present compressed air system technology, it has been further discovered by the developers that at least when applied to some aircraft, the compressed air system may have plumbing lengths that are sufficiently long to be potentially affected by standing wave resonances, pressure pulsations, vibrations, noise and other stresses. It has been found that such additional stresses may pose a risk in at least some cases of premature deterioration of one or more of the compressed air system components. FIG.1illustrates an aircraft engine10of a type preferably provided for use in subsonic flight, generally comprising a shaft12operatively connectable to a fan or other rotor, such as a helicopter rotor, for propelling ambient air, and in serial flow communication a compressor section14for pressurizing ambient air, a combustor16in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section18for extracting energy from the combustion gases. Components of the engine10are rotatable about a longitudinal center axis2of the engine10. In the present embodiment, the engine10is a turboshaft engine. It is contemplated that the engine10could be a different type of engine, such as a rotary engine, a turboprop, or a turbofan engine for example. FIG.2schematically illustrates an aircraft20, in this example a helicopter, having a first engine10′, and a second engine10″. The engines10′,10″ are operable to provide motive power to the aircraft20via conventional transmission systems and controls. For simplicity, only the non-conventional aspects of the present technology are described in detail in this document. In this embodiment, each of the engines10′,10″ is substantially the same as engine10shown inFIG.1and described above. Therefore, only the first engine10′ is described in further detail. Parts of the second engine10″ that correspond to parts of the first engine10′ are labeled with the same numerals. As shown schematically inFIG.2, the first engine10′ includes a first bleed air conduit22and a second bleed air conduit24, both of which bleed compressed air from respective parts of the compressor section14of the first engine10′. In the present embodiment, the first bleed air conduit22includes a check valve24′ and branches off into supply bleed air conduits23downstream of the check valve. In this embodiment, the second bleed air conduit24includes a check valve24′ and a check valve22′. The second bleed air conduit24branches off into supply bleed air conduits25at one or more locations that are fluidly in between the check valves24′,24″. As shown, the check valves24′,24″ are pointing toward each other, for purposes explained below. The supply bleed air conduits23,25deliver bleed air to various sealing systems of the first engine10′. The particular number and configuration of the sealing systems may be any suitable number and configuration, and is therefore not described in detail. The supply bleed air conduits23and25may also provide bleed air for various other functions of the first engine10′ and/or the aircraft. Examples of such functions include, but are not limited to, cooling of turbines, provision of environmental control of the cabin, operation of air systems, and pressurizing liquid tanks. Any suitable air piping and controls arrangement may be used to provide for each particular combination of the functions provided for by the bleed air from the first and second bleed air conduits22,24. Still referring toFIG.2, the first and second bleed air conduits22,24of the first engine10′ fluidly converge/join into a common bleed air conduit26. The common bleed air conduit26fluidly connects to a control valve28. The control valve28may be any suitable one or more control valves so long as it provides for the functionality described in this document. The conduits22,23,24,25,26and valves22′,24′,24″ of the first engine10′ are part of a bleed air system27of the first engine10′. The rest of the bleed air system27may be conventional and is therefore not shown or described in detail herein. As shown inFIG.2, in the present embodiment, the bleed air system29of the second engine10″ is similar to the bleed air system27of the first engine10′, described above. Therefore, to maintain simplicity of this description, the bleed air system29of the second engine10″ is not described in detail. Suffice it to say that parts of the bleed air system29of the second engine10″ that correspond to parts of the bleed air system27of the first engine10′ are labeled with the same numerals. As shown inFIG.2, the common bleed air conduit26of the second engine10″, similar to the common bleed air conduit26of the first engine10′, fluidly connects to a control valve28. The control valve28is operable by a controller of the aircraft20to selectively: i) fluidly connect the common bleed air conduit26of the first engine10′ to the common bleed air conduit26of the second engine10″, by fluidly unblocking the air pressure line that the control valve28is in, and ii) fluidly disconnect the common bleed air conduit26of the first engine10′ from the common bleed air conduit26of the second engine10″, by fluidly blocking the air pressure line that the control valve28is in, as illustrated by the internal structure of the control valve28schematically shown inFIG.2. The control valve28may be actuated using any suitable actuator of the engines10′,10″ and/or of the aircraft20. FIG.2shows a first in-flight, mode of operation of the aircraft20during which both engines10′,10″ are “active” and are therefore both providing motive power to the aircraft20. For the purposes of this document, the term “active” used with respect to a given engine means that the given engine is providing motive power to the aircraft with which it is used. In this operating condition, the bleed air system27of the first engine10′ and the bleed air system29of the second engine10″ are both self-sufficient. For the purposes of this document, the term “self-sufficient” used with respect to a given bleed air system of a given engine means that the given bleed air system of the given engine provides all of its intended functions for the duration of the time during which it is called upon to provide for the functions. A given bleed air system of a given engine is not “self-sufficient” when one or more of the intended functions of the given bleed air system may be unavailable or unstable due to a lack of bleed air pressure and/or bleed air supply rate provided by the corresponding engine to the given bleed air system. Reference is now made toFIG.3, which shows a second in-flight, cruise, mode of operation of the aircraft20during which: i) the first engine10′ is “active” and is therefore providing motive power to the aircraft20, and ii) the second engine10″ is on “standby” (a.k.a. operating in a standby mode) and is therefore not providing any material amount of motive power to the aircraft20. In this operating mode (i.e. in the second in-flight mode of operation), the bleed air system27of the first engine10′ is self-sufficient. On the other hand, depending on each particular embodiment of the engines10′,10″ and/or the aircraft20and/or on the characteristics of the particular “standby” operation of the second engine10″, the bleed air system29of the second engine10″ may or may not be self-sufficient in the standby mode. For this reason, during the second in-flight mode of operation of the aircraft20, the control valve28may be actuated by a suitable controller of the aircraft20to fluidly connect the common bleed air conduit26of the first engine10′ to the common bleed air conduit26of the second engine10″, to provide for an additional supply of bleed air from the bleed air system27of the first engine10′ to the bleed air system29of the second engine10″. Self-sufficiency of the bleed air system29of the second engine10″ may thereby be provided. After the second engine10″ is brought into an “active” state while the first engine10′ is in an “active” state, the control valve28may be actuated by a suitable controller of the aircraft20to fluidly disconnect the common bleed air conduit26of the first engine10′ from the common bleed air conduit26of the second engine10″, as shown inFIG.2. After the first engine10′ is put into a standby mode or a sub-idle mode while the second engine10″ is in an “active” mode, the control valve28may be actuated by a suitable controller of the aircraft20to fluidly connect the common bleed air conduit26of the first engine10′ to the common bleed air conduit26of the second engine10″. The bleed air system29of the second engine10″ may thereby provide compressed air to the bleed air system27of the first engine10′. Self-sufficiency of the bleed air system27of the first engine10′ may thereby be provided. The bleed air systems27,29of the engines10′,10″ and the control valve28are part of an air system30of the aircraft20. As described above, the air system30of the aircraft20implemented according to the present technology may thereby provide for self-sufficient operation of at least one of the engines10′,10″ in at least some operating conditions of the aircraft20in which at least some prior art engine bleed air systems may not be self-sufficient. Further, as shown inFIGS.2and3for example, in the present embodiment, the check valves24′ and24″ are provided in the bleed air conduits24, downstream of the branching-out bleed air conduits25. In this embodiment, this the branching-out bleed air conduits25may supply compressed air to at least some subsystems of the respective engines10′,10″. Each of the check valves24′ and24″ ensures that when the engine10′,10″ having that check valve24′,24″ is providing compressed air from its bleed air system27,29to the bleed air system27,29of the other engine10′,10″, the compressed air is provided from the air source corresponding to the bleed air conduit22of that engine10′,10″. The check valves24′ and24″ therefore help ensure uncompromised self-sufficient operation of the subsystems of the one of the engines10′,10″ that may at a given time be providing compressed air to the other one of the engines10′,10″. In some embodiments, the check valve24′ and/or the check valve24″ may be omitted. The rest of the air system30that is not shown in the figures of the present application may be conventional and is therefore not described in detail herein. Any suitable controls and any suitable control logic may be used to provide for the functionality of the air system30, and/or for various timings of actuation of the control valve28relative to switches between “active” and “standby” states that may occur with respect to each of the engines10′,10″ during in-flight or ground operations of the aircraft20. Referring now toFIG.4, an air system40of the aircraft20, which is an alternative embodiment of the air system30is shown. The air system40is similar to the air system30, and therefore similar reference numerals have been used for the air system40. A difference of the air system40from the air system30, is that air system40includes a control valve41, a control valve42, and an external compressed air source43such as an auxiliary power unit (APU) and/or an air compressor for example. The external compressed air source43may be any conventional external compressed air source suitable for each particular embodiment of the engines10′,10″ and the aircraft20. The control valve41selectively fluidly connects the external compressed air source43to the common bleed air conduit26of the first engine10′, via any suitable corresponding air conduits. More particularly, when the first engine10′ is “active”, the control valve41may be actuated by a suitable controller of the aircraft20to fluidly disconnect the external compressed air source43from the common bleed air conduit26of the first engine10′, and may thereby allow the bleed air system27of the first engine10′ to run self-sufficiently. When the first engine10′ is on “standby”, the control valve41may be actuated by a suitable controller of the aircraft20to fluidly connect the external compressed air source43to the common bleed air conduit26of the first engine10′. The control valve41may thereby provide “supplemental” compressed air to the bleed air system27of the first engine10′ at a supply rate and pressure sufficient to allow the bleed air system27of the first engine10′ to provide for all of its intended functions during the “standby” operation of the first engine10′. The control valve41, via corresponding air conduit(s), may selectively fluidly connect the external compressed air source43to a different part of the bleed air system27of the first engine10′, so long as the functionality described above is provided. The control valve42similarly fluidly connects the external compressed air source43to the common bleed air conduit26of the second engine10″, and is actuated according to a similar control logic to allow the bleed air system29of the second engine10″ to provide for all of its intended functions during the “standby” operation of the second engine10″. As shown, the control valve28that fluidly connects the bleed air system27of the first engine10′ to the bleed air system29of the second engine10″ may be in a position in which it fluidly disconnects the first engine10′ from the second engine10″, to allow for the supplemental compressed air to be provided to either one, or to both, of the engines10′,10″ by the external compressed air source43. In some embodiments, the control valves28,41,42may be actuated correspondingly to switch between the various possible supply modes of air described above. For example, in some operating conditions, the bleed air system27,29of one of the engines10′,10″ may receive “supplemental” compressed air from one or both of: i) the bleed air system27,29of another one of the engines10′,10″, and ii) the external compressed air source43. Referring now toFIG.5, an air system50of the aircraft20, which is yet another alternative embodiment of the air system30is shown. The air system50is similar to the air system40, and therefore similar reference numerals have been used for the air system50. A of the air system50difference from the air system40, is that air system50does not have a control valve28for fluidly connecting the bleed air system27of the first engine10′ to the bleed air system29of the second engine10″. Operation of the air system50is similar to operation of the air system40with respect to the external compressed air source43. In at least some embodiments and applications, the air systems30,40,50may allow to provide “supplemental” compressed air to the bleed air system27,29of one of the engines10′,10″ in at least some cases where that bleed air system27,29is malfunctioning and/or leaking air for example. A person skilled in the art will appreciate that while a particular air conduit arrangement is shown inFIGS.1to5, other air conduit arrangements may be used while providing for at least some of the functionality described in this document. While a single external compressed air source43is used in the embodiments ofFIGS.4and5, multiple different external compressed air sources may be used. Likewise, while the example aircraft20has two engines10′,10″, the present technology may be implemented with respect to more than two engines and/or with respect to other types of engines. With the above systems in mind, the present technology provides a method60of using, in flight, a source of pressurized air external to an engine of an aircraft20. As seen above, in some embodiments and operating conditions, the source of pressurized air may be one of the engines10′,10″ of the aircraft20, and in some embodiments, an APU43or air compressor43of the aircraft20. In some embodiments, the method60includes a step61of operating a given engine10′,10″ of the aircraft20during flight. In some embodiments, the method60also includes a step62of directing pressurized air from the source of pressurized air external to the given engine10′,10″, to a bleed air system27,29of the given engine10′,10″. In some embodiments, the given engine10′,10″ to which pressurized air is directed is a first engine10′ of the aircraft20, the aircraft20includes a second engine10″, and the source of pressurized air external to the first engine10′ is a bleed air system29of the second engine10″. As seen above, in some embodiments, the aircraft20is a multi-engine helicopter in which the engines10′,10″ are operatively connected to drive at least one main rotor of the helicopter to provide motive power to/propel the helicopter. As seen above, in some embodiments, the directing pressurized air to the bleed air system27of the first engine10′ is executed when the first engine10′ is operating on standby. In embodiments in which the source of the pressurized air is the bleed air system29of the second engine10″, the second engine10″ is active (i.e. providing motive power to the helicopter). Similarly, in some operating conditions during flight, the given engine10′,10″ to which pressurized air is directed is a second engine10″ of the aircraft20. In some such cases, the source of pressurized air external to the second engine10″ is a bleed air system27of the first engine10′. In some such cases, the second engine10″ is on standby while the first engine10′ providing the compressed air is active (i.e. providing motive power to the helicopter). As seen above, in some embodiments, the source of pressurized air is a first source of pressurized air (e.g. first engine10′ or second engine10″, depending on which of these engines is active and which is on standby), the aircraft20includes a second source of pressurized air (e.g. APU/air compressor43of the aircraft20). In some such embodiments, the second source of pressurized air43is external to both the first engine10′ and the second engine10″. In some such embodiments and in some flight conditions, the method60comprises directing pressurized air from the second source of pressurized air43to the first engine10′. In some such embodiments and in some flight conditions, the method60comprises directing pressurized air from the second source of pressurized air43to the second engine10″. Further in some such embodiments and in some flight conditions, the method60comprises directing pressurized air from the second source of pressurized air43to both the first engine10′ and the second engine10″. Further with the structure of the aircraft20described above, the present technology also provides method70of operating a bleed air system27of a first gas turbine engine10′ of a multi-engine aircraft20during flight. In some embodiments, the method70comprises a step71of operating the first gas turbine engine10′ of the aircraft20during flight in a standby mode, such as an idle or a sub-idle mode that provides either no motive power or at least materially no motive power to the aircraft20. In some embodiments, the method70comprises a step71of operating a second gas turbine engine10″ of the aircraft20during flight in an active mode (i.e. providing non-substantially-zero motive power to the aircraft20). In some cases, the steps71and72are executed simultaneously. In some such cases, the method70comprises directing pressurized air from a bleed air system29of the second gas turbine engine10″ to a bleed air system27of the first gas turbine engine10′. In some cases, the method70further includes a step73of operating a source of pressurized air (E.g. APU/air compressor43, and the like) of the aircraft20external to both the first gas turbine engine10′ and the second gas turbine engine10″, and a step of directing pressurized air from the source of pressurized air43to at least one of the first gas turbine engine10′ and the second gas turbine engine10″. In some cases, the directing pressurized air from one of the bleed air systems27,29to the other one of the bleed air systems27,29(depending on which one of the bleed air systems27,29requires supplemental compressed air) may be executed simultaneously with directing pressurized air from a second source of pressurized air to the one of the bleed air systems27,29that is receiving the supplemental compressed air. In some embodiments, the second source of pressurized air43includes, or is, at least one of: an APU43of the aircraft20, and an air compressor43of the aircraft20. In some such cases, the air pressure in the one of the bleed air systems27,29receiving supplemental compressed air may be lower than the pressure of the supplemental compressed air. It is contemplated that any suitable controls and control arrangements may be used to provide for this pressure differential, where required. While two engines10′,10″ of an aircraft20are described, it is contemplated that the present technology could be implemented with regard to a larger number of engines of an aircraft to provide supplemental compressed air from one or more of the engines or other compressed air source(s), to one or more other ones of the engines. The air systems30,40,50described above may help improve switching between active modes of operation and the sub-idle modes of operation of one or more engines of a multi-engine aircraft, as the sub-idle modes are described in the commonly owned U.S. patent application Ser. No. 16/560,365, entitled “CONTROL LOGIC FOR GAS TURBINE ENGINE FUEL ECONOMY”, filed Sep. 4, 2019, and incorporated by reference herein in its entirety. Now referring back toFIGS.2to5, in some embodiments, the air systems30,40,50may further comprise one or more pressure wave dampers31in air communication with one or more of the air pressure lines/conduits22-26. A non-limiting example of one of the pressure wave dampers31is shown in detail inFIG.5. The term “pressure wave damper” as used herein includes all devices that may in the present art be referred to as a pressure wave arrestor, pressure wave suppressor, pressure wave attenuator, and the like, and their equivalents including one or more branch pipes configured to filter out one or more frequencies associated with the unwanted pressure waves. The pressure wave damper(s)31may absorb and/or dampen and/or attenuate at least some of the pressure waves/pulses/air pressure fluctuations/pulsations in the air pressure line(s)/conduit(s)22-26that may be generated during operation of the air systems30,40,50, such as through executing the various methods60,70described above for example. In at least some cases, like steady state operation, this may help reduce a likelihood of standing wave resonances in the air systems30,40,50, and may help prolong an expected life cycle of the air systems30,40,50. In at least some embodiments, at least some of the pressure wave dampers31are made large enough to act as resonators during steady state engine operation, thereby helping dissipate transient/surge pressure within the respective line(s) to which it/they are connected. For example, for effectiveness during a steady state operation, the neck dimensions (length and diameter) of a given pressure wave damper31may be tuned to resonate with the accompanying volume of the given pressure wave damper31at the most prevalent excitation frequency and/or an Eigen frequency of the corresponding air pressure line, to dissipate energy that may be imparted to the air pressure line, for example as a result of a control valve operation and/or a switchover of an engine from a standby mode to an active mode and/or vice versa, prior to distressing the air pressure line. As shown, in some embodiments, the pressure wave damper(s)31may be fluidly connected into the air systems30,40,50at locations proximate to one or more of the valves, for example valves22′,24′,24″,28,41,42, of the air systems30,40,50. Also as shown, in some embodiments, the pressure wave damper(s)31may be fluidly connected into the air systems30,40,50at locations each of which may have been determined to correspond to an air pressure maxima, and/or a maximum of a pressure wave inside the corresponding duct(s), pipe(s) or other air conduit(s), in the respective air system30,40,50. Such positioning may help further reduce a likelihood of, and in some embodiments and applications prevent, standing wave resonances in the air systems30,40,50, and may further help prolong life of the air systems30,40,50. More particularly, the air pressure maximums may be determined at one or more switch-over conditions of the air systems30,40,50, as described above (a.k.a. transient operation), during which the air systems30,40,50may switch, for example: a) from supplying one of the engines10′,10″ with supplemental compressed air to supplying another one of the engines10′,10″ with supplemental compressed air, or b) from not supplying any supplemental compressed air to any of the engines10′,10″ to supplying supplemental compressed air to at least one of the engines10′,10″. More particularly, for a given air pressure line having a control valve, such as one or more of the control valves28,41,42for example, the air pressure maximum, and/or the maximum of a pressure wave, may be calculated (e.g. by modeling) as a maximum air pressure in the air pressure line when the control valve switches between one of: i) from fluidly blocking the air pressure line to fluidly unblocking the air pressure line, and ii) from fluidly unblocking the air pressure line to fluidly blocking the air pressure line. In some embodiments, one or more of the pressure wave damper31may be a Helmholtz resonator. In some embodiments, one or more of the pressure wave damper31may include a membrane/diaphragm that is fluidly and/or mechanically pressurized to enhance a frequency response of the respective air systems30,40,50. In some embodiments, one or more of the pressure wave damper31may include a resonator volume that absorbs and/or attenuates and/or dissipates shockwaves and/or pressure oscillations and/or other aerodynamic instabilities. In some such embodiments, the resonator volume(s) may be spherical, cylindrical, or a 3D complex shape for example, and may be made sufficiently large to dissipate transient/surge pressure within the respective air lines, to assist in mitigating stresses during the transient operations of the air systems30,40,50. Also, in some embodiments, one or more of the pressure wave dampers31may include a neck32(numbered inFIG.2only, to preserve clarity of the figures) that fluidly connects the resonator volume(s) to the respective air lines. In some such embodiments, the resonator neck dimensions, including a length and diameter thereof, may be selected to resonate with the corresponding resonator volume(s) at a prevalent excitation frequency and/or at an Eigen frequency of the corresponding air line. In at least some cases, such dimensioning may help reduce stresses experienced by the respective air systems30,40,50during steady state operation. Also, in some embodiments, such as where a Helmohltz resonator is used, the Helmohltz resonator may have an opening having an opening area (A), a neck with a length (L), and a volume (V). In such embodiments, the resonator frequency response of the Helmohltz resonator, or resonance, which may be tuned, may be expressed as the following function: V=c0/2/pi*sqrt(A/V/L), where c0 is the velocity of the sound. The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the disclosed technology. | 29,049 |
11859537 | DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION The following description may use terms such as “horizontal”, “vertical”, “lateral”, “back and forth”, “up and down”, “upper”, “lower”, “inner”, “outer”, “forward”, “rear”, etc. These terms generally refer to the views and orientations as shown in the drawings and that are associated with a normal use of the invention. The terms are used for the reader's convenience only and shall not be limiting. Referring initially toFIG.1, the gas turbine engine according to the invention comprises in general the following three units, one nested within the other and arranged about a common axis of rotation CL: a power output turbine unit (POT)300which is rotatably arranged inside an outer housing unit200, and a compressor-turbine unit (CTU)400which is rotatably arranged inside the POT300. In the following, the compressor-turbine unit (CTU) is also referred to as first turbine unit400, and the power output turbine unit (POT) is also referred to as a second turbine unit300. The housing200may be mounted on a vehicle, vessel or other foundation, using mounting assemblies (not shown) that are well known in the art. It should be understood that several parts (e.g. seals, fittings, bearings, control units, fuel supply) that generally are required in a gas turbine engine have been omitted from the drawings, as these parts are well known in the art and not required for illustrating the invention. By the same token, materials are not specified, as the skilled person will know which material qualities and properties are suitable for a gas turbine engine. Referring now toFIGS.1and2, the housing200comprises a first opening201and a second opening202, each provided with seals and bearings203. Reference number204denotes a typical exhaust gas outlet. Referring now toFIGS.1and3, the power output turbine unit (POT)300comprises an output shaft301, which is configured to be rotatably arranged in the above-mentioned second opening202in the housing200. The output shaft may be connected to a utility device, for example an aircraft propeller or fan, or an electric generator. The invention shall not be limited to such applications. The POT300also comprises a turbine section310(generally indicated by the dotted line310inFIG.3and hereinafter referred to as the “third stage”), which comprises a plurality of turbine blades311arranged in the region of an open end portion of a channel312. A circular portion302forms a shaft about the central axis CL. The POT300also comprises a compressor housing section320(generally indicated by the dotted line320inFIG.3), which comprises a cavity321and orifices322. Although the POT300is illustrated as one singular object in which the compressor housing320and the third stage310are rigidly connected, it should be understood that the compressor housing320and the third stage310may be mechanically connected via e.g. a gearbox14, indicated schematically with dotted lines inFIG.3. As an option, turbine blades322amay be installed in the housing section320, whereby the orifices322are defined by the blades, seeFIGS.6and7. Referring now toFIGS.1and4, the compressor-turbine unit (CTU)400generally comprises a compressor-turbine section410(generally indicated by the dotted line410inFIG.4and hereinafter referred to as the “second stage”) and a turbine section420(generally indicated by the dotted line420inFIG.4and hereinafter referred to as the “first stage”). The first410and second420stages are interconnected by circular portion402forming a shaft about the central axis CL. Reference number401denotes a gas (air) inlet. In the illustrated embodiment, the first stage420is a radial turbine having turbines blades421arranged upstream of an outlet duct422and an orifice423between turbine blades. The second stage410comprises turbine blades411arranged such that an outlet duct412and opening413is formed between the blades. Referring now toFIG.1, the CTU400is rotatably arranged inside the POT300. More specifically, the CTU shaft402(the inside of which forms the air inlet401) is rotatably supported in the POT circular portion (shaft)302, forming between them a cavity10into which seals and bearings (not shown) may be arranged. The first stage420is rotatably arranged in the compressor housing section320, such that air (or other gases) having passed the turbine blades421of the first stage420are ejected through the first outlet opening423(between turbine blades) and the orifice322, and into a combustion chamber12formed by a portion of the housing wall and a portion of the shaft302. It should be understood that the combustion chamber may have other configurations.FIG.1also illustrates how the second stage410is rotatably arranged inside the third stage310; in the channel312. When the gas turbine engine is operating, a gas (e.g. air) enters the inlet401in the CTU400, as indicated by the arrows. Inside the CTU, the gas encounters the high-speed radial compressor in the first stage420and is given an increase in momentum and velocity and then ejected through the first orifices423and the second orifices322, and into the combustion chamber12. The combustion chamber is furnished with a fuel supply system of a known type and therefore not illustrated. The combusted gas is forced towards the exhaust gas outlet204, and therefore passes—and imparts momentum to—the second stage blades411and the third stage blades311. The aerodynamic friction caused by and between the rotating POT300and CTU400will contribute to the output power and thus result in an increased efficiency of the gas turbine engine. More specifically, the close proximity between the POT300and the CTU400generates a dynamic friction coupling between the two units: the friction caused against the POT300by the rotating CTU400contributes to the rotation of the POT300, and vice versa. This contributes to the output power and to an increase of efficiency. Referring toFIG.5, it will be understood that the distance d between the POT300and the CTU400may be dimensioned according to the specific requirements. The inner surface area of the POT300and the outer surface area of the CTU400may also be configured and formed to optimize the friction coupling between the two units. For example, surfaces may (partly or completely) be provided with structures (e.g. ridges and grooves) that promote aerodynamic friction. It should be understood that the gas turbines described above may be axial turbines, radial turbines, or a combination of both. The invention shall not be limited to the type of gas turbines. In the embodiments described above, various features and details are shown in combination. The fact that several features are described with respect to a particular example should not be construed as implying that those features by necessity have to be included together in all embodiments of the invention. Conversely, features that are described with reference to different embodiments should not be construed as mutually exclusive. As a person skilled in the art readily will understand, embodiments that incorporate any subset of features described herein and that are not expressly interdependent have been contemplated by the inventor and are part of the intended disclosure. However, explicit description of all such embodiments would not contribute to the understanding of the principles of the invention, and consequently some permutations of features have been omitted for the sake of simplicity or brevity. | 7,497 |
11859538 | DETAILED DESCRIPTION FIG.1schematically illustrates an example gas turbine engine20that includes a fan section22, a compressor section24, a combustor section26and a turbine section28. The fan section22drives air along a bypass flow path B while the compressor section24draws air in along a core flow path C where air is compressed and communicated to a combustor section26. In the combustor section26, air is mixed with fuel and ignited to generate a high pressure exhaust gas stream that expands through the turbine section28where energy is extracted and utilized to drive the fan section22and the compressor section24. Although the disclosed non-limiting embodiment depicts one gas turbine engine, it should be understood that the concepts and teachings described herein may be applied to other types of turbine engines; for example a turbine engine including a three-spool architecture in which three spools concentrically rotate about a common axis and where a low spool enables a low pressure turbine to drive a fan via a gearbox, an intermediate spool that enables an intermediate pressure turbine to drive a first compressor of the compressor section, and a high spool that enables a high pressure turbine to drive a high pressure compressor of the compressor section. The example engine20generally includes a low speed spool30and a high speed spool32mounted for rotation about an engine central longitudinal axis A relative to an engine static structure36via several bearing systems38. It should be understood that various bearing systems38at various locations may alternatively or additionally be provided. The low speed spool30generally includes an inner shaft40that connects the fan section22and a low pressure (or first) compressor section44to a low pressure (or first) turbine section46. The inner shaft40drives the fan section22through a speed change device, such as a geared architecture48, to drive the fan section22at a lower speed than the low speed spool30. The high-speed spool32includes an outer shaft50that interconnects a high pressure (or second) compressor section52and a high pressure (or second) turbine section54. The inner shaft40and the outer shaft50are concentric and rotate via the bearing systems38about the engine central longitudinal axis A. A combustor56is arranged between the high pressure compressor52and the high pressure turbine54. In one example, the high pressure turbine54includes at least two stages to provide a double stage high pressure turbine54. As used herein, a “high pressure” compressor or turbine experiences a higher pressure than a corresponding “low pressure” compressor or turbine. The example low pressure turbine46has a pressure ratio that is greater than about 5. The pressure ratio of the example low pressure turbine46is measured prior to an inlet of the low pressure turbine46as related to the pressure measured at the outlet of the low pressure turbine46prior to an exhaust nozzle. The low pressure turbine46is coupled to the fan section22through the geared architecture48and therefore is also referred to interchangeably in this disclosure as the fan drive turbine46. A mid-turbine frame58of the engine static structure36is arranged generally between the high pressure turbine54and the low pressure turbine46. The mid-turbine frame58further supports bearing systems38in the turbine section28as well as setting airflow entering the fan drive turbine46. Airflow through the core airflow path C is compressed by the low pressure compressor44then by the high pressure compressor52mixed with fuel and ignited in the combustor56to produce high speed exhaust gases that are then expanded through the high pressure turbine54and fan drive turbine46. The mid-turbine frame58includes vanes60, which are in the core airflow path and function as an inlet guide vane for the low pressure turbine46. Utilizing the vane60of the mid-turbine frame58as the inlet guide vane for low pressure turbine46decreases the length of the low pressure turbine46without increasing the axial length of the mid-turbine frame58. Choosing a high gearbox input to output ratio, reduces the number of vane rows in the fan drive turbine46and shortens the axial length of the turbine section28. Thus, the compactness of the gas turbine engine20is increased and a higher power density may be achieved. The disclosed gas turbine engine20in one example is a high-bypass geared aircraft engine. In a further example, the gas turbine engine20includes a bypass ratio greater than about eight (8), with an example embodiment being greater than about twelve (12). The geared architecture48is an epicyclical gear train, such as a planetary gear system, star gear system or other known gear system, with a gear reduction ratio of greater than about 2.6. In one disclosed embodiment, the gas turbine engine20includes a bypass ratio greater than about twelve (12:1) and a diameter of the fan blades42is significantly larger than an outer diameter of the low pressure compressor44. It should be understood, however, that the above parameters are only exemplary of one embodiment of a gas turbine engine including a geared architecture and that the present disclosure is applicable to other gas turbine engines. A significant amount of thrust is provided by flow through the bypass flow path B due to the high bypass ratio. The fan section22of the engine20is designed for a particular flight condition—typically cruise at about 0.8 Mach and about 35,000 feet. The flight condition of 0.8 Mach and 35,000 ft., with the engine at its best fuel consumption—also known as “bucket cruise Thrust Specific Fuel Consumption (‘TSFC’)”—is the industry standard parameter of pound-mass (lbm) of fuel per hour being burned divided by pound-force (lbf) of thrust the engine produces at that minimum point. “Low fan pressure ratio” is the pressure ratio across the fan blade alone, without a Fan Exit Guide Vane (“FEGV”) system. The low fan pressure ratio as disclosed herein according to one non-limiting embodiment is less than about 1.50. In another non-limiting embodiment, the low fan pressure ratio is between 1.45 and 1.20. “Low corrected fan tip speed” is the actual fan tip speed in ft/sec divided by an industry standard temperature correction of [(Tram °R)/(518.7°R)]0.5. The “Low corrected fan tip speed”, as disclosed herein according to one non-limiting embodiment, is less than about 1150 ft/second. The example gas turbine engine includes the fan section22that comprises in one non-limiting embodiment less than about 26 fan blades42. In another non-limiting embodiment, the fan section22includes less than about 20 fan blades42. Moreover, in one disclosed embodiment the low pressure turbine46includes no more than about 6 turbine rotor stages schematically indicated at34. In another non-limiting example embodiment, the low pressure turbine46includes about 3 turbine rotor states. A ratio between the number of fan blades42and the number of low pressure turbine rotors is between about 3.3 and about 8.6. The example low pressure turbine46provides the driving power to rotate the fan section22and therefore the relationship between the number of turbine rotor stages34in the low pressure turbine46and the number of blades42in the fan section22disclose an example gas turbine engine20with increased power transfer efficiency. An example disclosed engine20provides a system-level combination of component (module) efficiencies and a system-level combination of features within these modules that are used to arrive at uniquely high engine efficiency (i.e. Thrust Specific Fuel Consumption) at takeoff and at bucket cruise. The disclosed combination of components provide benefit in a commercial engine with very high bypass ratio in achieving the stated, very low, thrust specific fuel consumption (see table1) and is especially beneficial to a single aisle aircraft where the overall pressure ratio of the compressor is less than 50. TABLE 1Sea level takeoff,[2]Sea level takeoff,86 deg F., 0.0 Mn:86 deg F., 0.0 Mn:Test Stand Operation:Test Stand Operation:no power extraction, nono power extraction, noBucket Cruise,Environmental ControlEnvironmental Control0.8 Mn, 35,000 ft,System bleedSystem bleedStandard DayThrust Specific Fuel0.27510.53717Consumption [1]Speed changeAt least2.62.6(Input/output)Component efficiencyFan ODat least 0.900.93440.96501Speed Change Mechanismat least 0.9850.99490.99374First Compressor or LPCat least 0.840.86950.86622Second Compressor or HPCat least 0.820.84950.8356Turbine Section(s)at least 0.85 for the single0.875440.8938excluding theHPT or combinedfan drive turbineefficiency if two or moreturbines are usedFan Drive turbineat least 0.890.92510.9266 The combination of module efficiency includes among other possible things, the fan section22with the fan blades42supported on a fan hub64. Each of the fan blades42includes a leading edge62that extends a radial distance66from the engine axis A. The fan hub64extends a radial distance68from the engine axis A. A low hub-tip ratio of fan hub radial radius68to the radius at the leading edge62of the fan blade42is less than 0.34 and greater than 0.020. The disclosed range of ratios is desirable in that the lower this value is, the smaller the outer fan section and inlet section has to be to accommodate a given amount of air, and maintaining this dimension within the desired ratio range enables a reduction in engine weight relative to an engine with a higher hub to tip ratio. In one example embodiment, the fan section22further provides a low fan pressure ratio that is between about 1.45 and about 1.20, and a bypass ratio greater than about 8.0. The disclosed engine20includes the geared architecture48with a gear ratio greater than about 2.6 to 1. In this example, the speed change system is the geared architecture, which is an epicyclical gearbox and which includes planet gears or star gears interspersed by baffles for gathering and directing lubricant during operation. The example turbine section28has at least two turbine stages forward of the first turbine stage94included in the fan drive turbine46. In this example, the high pressure or second turbine includes two turbine stages96forward of the fan drive turbine46. In this example, the two turbine stages96are part of a single high pressure turbine54with at least two turbine rotors96, however, it is within the contemplation of this disclosure that the at least two turbine rotors forward of the fan drive turbine46could be part of multiple turbines that rotate independent of each other, for example, two separate turbine sections with at least one turbine rotor each. Referring toFIG.2, with continued reference toFIG.1, the first compression section44, which in one disclosed example is a low pressure compressor (LPC)44, includes three stages. The example LPC44includes first compressor blade70with a leading edge72and a last compressor blade74with trailing edge76. A tip of the leading edge72of the first blade70extends a radial distance78from the engine axis A. A tip of the trailing edge76of the last blade74extends a radial distance80from the engine axis A. The first compression section44is configured such that a ratio between the radial distance80at the trailing edge76is greater than 67% of the radial distance78of the leading edge72of the first blade70. The example configuration provided by the disclosed ratio enables improved airflow through the first compressor section44that provides improved efficiency. The disclosed relationship between the leading edge72and the trailing edge76enables a beneficial modest slope to the engine casing structures spanning the compressor section24. The modest slope provides for minimal effects to tip clearances of the compressor blades due to axial shifting of the compressor rotor due to overall aerodynamic loading. Referring toFIG.3with continued reference toFIG.1, the second compression section52, which in one disclosed example is a high pressure compressor (HPC), includes at least eight stages. The example HPC52includes a first blade82with a leading edge84that extends a radial distance86from the engine axis A to a tip. The second compressor section52also includes a last blade88having a trailing edge90that extends a radial distance92from the engine axis A to the tip. A ratio between the leading edge84and the trailing edge90defines the configuration of the compressor52that provides the improved efficiency. In one disclosed example, the radial distance92of the trailing edge90of the last blade88is greater than about 57% of the radial distance86of the leading edge84of the first blade82of the second compressor section52. A geared turbine arrangement for short range aircraft can uniquely exploit the particular aspects of an aircraft duty cycle that is characterized by an unusually low proportion of time in cruise operation versus the total time spent at takeoff and climb power (for a representative time span such as between engine overhauls). A definition of a short range aircraft is one with a total flight length less than about 300 nautical miles. TABLE 2Engine#1#2Max takeoff weight53,060 kg(117,000 lb)58,967 kg(130,000 lb)Max landing weight49,895 kg(110,000 lb)55,111 kg(121,500 lb)Maximum cargo3,629 kg(8,000 lb)4,853 kg(10,700 lb)payloadMaximum payload13,676 kg(30,150 lb)16,284 kg(35,900 lb)(total)Max range2,778 km(1,500 nmi)2,778 km(1,500 nmi)Take off run1,219 m(3,999 ft)1,524 m(5,000 ft)at MTOWLanding field1,341 m(4,400 ft)1,448 m(4,751 ft)length at MLW As is shown in Table 2, a short range aircraft for purposes of this disclosure is defined as including a single aisle configuration with 2, 3 seating or 3, 3 seating. Conventionally, a short range aircraft has a capacity of about 200 passengers or less. Moreover, an example short range aircraft will have a maximum range of only about 1500 nautical miles. Because of the extremely high utilization in terms of cumulative hours at relatively high power during take-off conditions, the disclosed geared turbine engine20arrangement is configured differently to achieve a beneficial balance of fuel burn and maintenance costs. The high power utilization is a result of frequent operation at high power conditions that generate high turbine temperatures, elevated turbine cooling air temperatures and elevated temperatures at the rear stage of the compressor. The result of such operation is that LPC pressures rise, temperature rise and efficiency may be lower than for a long range aircraft. In a long range aircraft that operates for longer periods and a greater portion of the cumulative operating hours, maximizing LPC efficiency is desired provides a significant benefit, and is a key difference when compared to short range aircraft. Pressure and temperature rise can be increased due to the less frequent use of takeoff power between overhaul periods which could be around 4000 hours for both the short range and long range commercial airliner. Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the scope and content of this disclosure. | 15,285 |
11859539 | Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention. DETAILED DESCRIPTION Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. Embodiments of an aircraft and propulsion system are provided that include an inter-turbine reheat burner positioned between a first turbine and a second turbine. A first fuel system provides a liquid fuel to a combustion section to generate combustion gases to the turbines. A second fuel system provides a gaseous fuel to the inter-turbine burner to selectively generate reheat gases based on particular engine or aircraft operating conditions. Embodiments of the propulsion system are further configured to generate particular ratios of thrust or power output based on the first fuel system versus the first fuel system and second fuel system together. Embodiments of the propulsion system and aircraft provided herein allow for relatively smaller core engine sizes (i.e., the size and power output of the high pressure spool, the combustion section, and the high pressure turbine together) while generating rated power outputs similar to larger core engine sizes, via increased power extraction from the low pressure spool. Smaller core engine sizes allow for reduced fuel consumption, reduced emissions, greater bypass ratios and improved specific fuel consumption. Smaller core engine sizes may also allow for operating the propulsion system as an auxiliary power unit (APU) to power aircraft subsystems, electronics, or provide engine starting power to other propulsion systems, without the use of dedicated APUs separate from the propulsion system. Such systems allow for improving overall aircraft efficiency, such as by removing a need or desire for non-propulsion gas turbine engines. Referring now to the drawings, inFIG.1, an exemplary embodiment of a vehicle100including a propulsion system10with an inter-turbine burner according to aspects of the present disclosure is provided. In an embodiment, the vehicle100is an aircraft including an aircraft structure or airframe105. The airframe105includes a fuselage110to which wings120and an empennage130are attached. The propulsion system10according to aspects of the present disclosure is attached to one or more portions of the airframe. In various embodiments, the aircraft100includes a thermal management system200configured to desirably distribute thermal loads, such as to add or remove heat from one or more fluids or structures, such as, but not limited to, oxidizer at the propulsion system, fuel, lubricant, hydraulic fluid, pneumatic fluid, or cooling fluid for an electric machine, electronics, computing system, environmental control system, gear assembly, or other system or structure. In still various embodiments, the aircraft100includes sub-systems generally defining an electric load requiring input energy. Such systems include an anti-icing system160, an environmental control system150, and an avionics system140. The propulsion system10is configured to extract energy from one or more spools to power the aircraft sub-systems, such as described herein. Although certain systems may be formed as mechanical systems, electrification of the systems may reduce aircraft weight and complexity. However, such electrification generally requires greater energy inputs, such as from the propulsion system10described herein. In certain instances, the propulsion system10is attached to an aft portion of the fuselage110. In certain other instances, the propulsion system10is attached underneath, above, or through the wing120and/or portion of the empennage130. In various embodiments, the propulsion system10is attached to the airframe105via a pylon or other mounting structure. In still other embodiments, the propulsion system10is housed within the airframe, such as may be exemplified in certain supersonic commercial aircraft. Referring now toFIG.2, a schematic cross-sectional view of a propulsion system for the aircraft in accordance with an exemplary embodiment of the present disclosure is provided. As shown inFIG.2, the propulsion system10defines an axial direction A (extending parallel to a longitudinal centerline12provided for reference), a radial direction R, and a circumferential direction (i.e., a direction extending about the axial direction A; not depicted). In various embodiments, the propulsion system10is configured as a gas turbine engine, such as a turbofan engine. In particular embodiments, the propulsion system10is a ductless open-rotor engine (i.e., without a nacelle surrounding the fan blades). In general, the propulsion system10includes a fan section14and a turbomachine16disposed downstream from the fan section14. The exemplary turbomachine16depicted generally includes a substantially tubular outer casing18that defines an annular inlet20. The outer casing18encases, in serial flow relationship, a compressor section including a first, booster or low pressure (LP) compressor22and a second, high pressure (HP) compressor24; a combustion section26; a turbine section including a first, high pressure (HP) turbine28and a second, low pressure (LP) turbine30; and a jet exhaust nozzle section32. A high pressure (HP) shaft34drivingly connects the HP turbine28to the HP compressor24. A low pressure (LP) shaft36drivingly connects the LP turbine30to the LP compressor22. The compressor section, combustion section26, turbine section, and jet exhaust nozzle section32are arranged in serial flow order and together define a core air flowpath37through the turbomachine16. In certain embodiments, the propulsion system10includes one or more electric machines370operably coupled to a spool of the engine. The electric machine370may be operably coupled to the HP spool, the LP spool, or both, to extract or receive energy from the spool during operation. Additionally, the electric machine370may be configured to output or discharge energy to the spool to start or aide rotation of the HP spool (e.g., during startup or other desired operation), or to the LP spool during desired operation of the aircraft (e.g., during cruise operation, or transient conditions, or for relative bursts of thrust or power output). In various embodiments described herein, the HP spool may be allowed to operate at a substantially steady-state condition, such as to allow for substantially steady-state extraction of energy to the electric machine. The electric machine may discharge energy to one or more sub-systems (e.g., sub-systems140,150,160) at the aircraft100. Particularly, embodiments of the propulsion system10provided herein allow for increased energy extraction from the HP spool. Still further, or alternatively, the system10may allow for power extraction during ground operation conditions, including ground idle or taxiing conditions. In a particular embodiment, such as depicted inFIG.2, the fan section14may include a variable pitch fan38. The turbomachine16is operably coupled to the fan38for driving the fan38. The fan38includes a plurality of rotatable fan blades40coupled to a disk42in a spaced apart manner. As depicted, the fan blades40extend outwardly from disk42generally along the radial direction R. Each fan blade40is rotatable relative to the disk42about a pitch axis P by virtue of the fan blades40being operatively coupled to a suitable actuation member44configured to collectively vary the pitch of the fan blades40, e.g., in unison. The fan blades40, disk42, and actuation member44are together rotatable about the longitudinal axis12by LP shaft36across a power gear box46. The power gear box46includes a plurality of gears for stepping down the rotational speed of the LP shaft36to a more efficient rotational fan speed. Accordingly, for the embodiment depicted, the turbomachine16is operably coupled to the fan38through the power gear box46. Referring still toFIG.2, the compressed second portion of air64from the compressor section mixes with liquid fuel and is burned within the combustion section to provide combustion gases66. The combustion gases66are routed from the combustion section26, through the HP turbine28where a portion of thermal and/or kinetic energy from the combustion gases66is extracted via sequential stages of HP turbine stator vanes68that are coupled to the outer casing18and HP turbine rotor blades70that are coupled to the HP shaft34, thus causing the HP shaft34to rotate, thereby supporting operation of the HP compressor24. The combustion gases66are then routed through the LP turbine30where a second portion of thermal and kinetic energy is extracted from the combustion gases66via sequential stages of LP turbine stator vanes72that are coupled to the outer casing18and LP turbine rotor blades74that are coupled to the LP shaft36, thus causing the LP shaft36to rotate, thereby supporting operation of the LP compressor22and/or rotation of the fan38. The combustion gases66are subsequently routed through the jet exhaust nozzle section32of the turbomachine16. Simultaneously, the pressure of the first portion of air62is substantially increased as the first portion of air62is routed through the bypass airflow passage56before it is exhausted from a fan nozzle exhaust section76of the propulsion system10, also providing propulsive thrust. The HP turbine28, the LP turbine30, and the jet exhaust nozzle section32at least partially define a hot gas path78for routing the combustion gases66through the turbomachine16. It will be appreciated that the exemplary propulsion system10depicted inFIG.2is a relatively large power class turbofan propulsion system10. Accordingly, when operated at the rated speed, the propulsion system10may be configured to generate a relatively large amount of thrust. More specifically, when operated at the rated speed, the propulsion system10may be configured to generate at least about 14,000 pounds of thrust, or at least 18,000 pounds of thrust, or at least 21,000 pounds of thrust, or at least 24,000 pounds of thrust, or at least 30,000 pounds of thrust. Certain embodiments may generate up to 120,000 pounds of thrust at the rated speed. Accordingly, the propulsion system10depicted inFIG.2may be referred to as a relatively medium-to-large power class gas turbine engine. It will be appreciated that other exemplary embodiments of the propulsion system10are relatively large power class turboshaft propulsion system10. Accordingly, when operated at the rated speed, the propulsion system10may be configured to generate a relatively large amount of horsepower. More specifically, when operated at the rated speed, the propulsion system10may be configured to generate up to 10,000 shaft horsepower (shp). In various embodiments, when operated at the rated speed, the propulsion system10may be configured to generate at least 2,000 shaft horsepower (shp). Moreover, it should be appreciated that the exemplary propulsion system10depicted inFIG.2is by way of example only, and that in other exemplary embodiments, the propulsion system10may have any other suitable configuration. For example, in certain exemplary embodiments, the fan may not be a variable pitch fan. Additionally, or alternatively, aspects of the present disclosure may be utilized with any other suitable aeronautical gas turbine engine, such as a turboshaft engine, turboprop engine, turbojet engine, etc. Further embodiments may omit the nacelle surrounding the fan blades, such as to form an open-rotor turbofan engine. It should be appreciated that, as used herein, rotation and modulation of speed of the HP spool and the LP spool correspond to generation and modulation of output torque, power, or thrust. In turbofan configurations of the propulsion system, the substantial majority portion of thrust is generated via rotation of the fan blades via the LP spool. In various embodiments, a remaining portion of thrust is generated via combustion gases exhausted through the exhaust jet nozzle. Referring now toFIG.3, a close-up view of a portion of the exemplary propulsion system10ofFIG.2is provided. More specifically,FIG.3provides a close-up view of the combustion section26and the turbine section. In a particular embodiment, the combustion section26includes a combustor assembly100. The combustor assembly100may be configured as a deflagrative combustor assembly, such as, but not limited to, an annular combustor, a dual-annular combustor, a can-annular combustor, a can combustor, a trapped vortex combustor, or other appropriate combustion system. The combustor assembly may be configured as a lean-burn combustor, a rich-burn combustor, a rich quench lean (RQL) combustor, or other appropriate combustor assembly. In one embodiment, the combustion section26includes a first fuel conduit, such as formed by one or more fuel nozzles124configured to receive a flow of liquid fuel, depicted schematically via arrows352, and provide the liquid fuel to a combustion chamber114for combustion or detonation. Although not depicted in further detail, the fuel nozzle124may be any appropriate type of fuel injector, nozzle, rail, or other liquid fuel dispensing device, atomizing device, or mixing device. In particular embodiments, the fuel nozzle124may be configured for lean or rich mixtures, combustion, or detonation. In certain embodiments, the combustor assembly100generally includes an inner liner102extending between an aft end and a forward end generally along the axial direction A, as well as an outer liner108also extending between an aft end and a forward end generally along the axial direction A. The inner and outer liners102,108together at least partially define a combustion chamber114therebetween. The inner and outer liners102,108are each attached to or formed integrally with an annular dome. More particularly, the annular dome includes an inner dome section116formed integrally with the forward end106of the inner liner102and an outer dome section118formed generally with the forward end of the outer liner108. Further, the inner and outer dome section116,118may each be formed integrally (or alternatively may be formed of a plurality of components attached in any suitable manner) and may each extend along the circumferential direction C to define an annular shape. It should be appreciated, however, that in other embodiments, the combustor assembly100may not include the inner and/or outer dome sections116,118; may include separately formed inner and/or outer dome sections116,118attached to the respective inner liner102and outer liner108; or may have any other suitable configuration. In still other embodiments, the combustion section26may be configured as a detonative combustion system, such as a rotating detonation combustion system or a pulse detonation combustion system. Referring still toFIG.3, the combustor assembly100further includes a plurality of fuel air mixers spaced along the circumferential direction C (not shown) and positioned at least partially within the annular dome. More particularly, the plurality of fuel air mixers are disposed at least partially between the outer dome section118and the inner dome section116along the radial direction R. Compressed air from the compressor section of the propulsion system10flows into or through the fuel air mixers, where the compressed air is mixed with fuel and ignited to create the combustion gases66within the combustion chamber114. The inner and outer dome sections116,118are configured to assist in providing such a flow of compressed air from the compressor section into or through the fuel air mixers124. For example, the outer dome section118may include an outer cowl at a forward end and the inner dome section116similarly includes an inner cowl at a forward end. The outer cowl and inner cowl may assist in directing the flow of compressed air from the compressor section into or through one or more of the fuel air mixers. Again, however, in other embodiments, the annular dome may be configured in any other suitable manner. Certain embodiments of the combustion section26or the turbine section may include one or more components formed of a ceramic matrix composite (CMC) material. In certain embodiments, the inner liner102and the outer liner108are each formed of CMC material. In still certain embodiments, vanes or struts of the frame300further described below are formed of CMC material. Still further embodiments include one or more stages of vanes or blade of the LP turbine30formed of CMC material. CMC material is a non-metallic material having high temperature capability. Exemplary CMC materials utilized for such components may include silicon carbide (SiC), silicon nitride, or alumina matrix materials and combinations thereof. Ceramic fibers may be embedded within the matrix, such as oxidation stable reinforcing fibers including monofilaments like sapphire and silicon carbide (e.g., Textron's SCS-6™), as well as roving and yarn including silicon carbide (e.g., Nippon Carbon's NICALON®, Ube Industries' TYRANNO®, and Dow Corning's SYLRAMIC®), alumina silicates (e.g., Nextel's 440 and 480), and chopped whiskers and fibers (e.g., Nextel's 440 and SAFFIL®), and optionally ceramic particles (e.g., oxides of Si, Al, Zr, Y, and combinations thereof) and inorganic fillers (e.g., pyrophyllite, wollastonite, mica, talc, kyanite, and montmorillonite). For example, in certain embodiments, bundles of the fibers, which may include a ceramic refractory material coating, are formed as a reinforced tape, such as a unidirectional reinforced tape. A plurality of the tapes may be laid up together (e.g., as plies) to form a preform component. The bundles of fibers may be impregnated with a slurry composition prior to forming the preform or after formation of the preform. The preform may then undergo thermal processing, such as a cure or burn-out to yield a high char residue in the preform, and subsequent chemical processing, such as melt-infiltration with silicon, to arrive at a component formed of a CMC material having a desired chemical composition. In other embodiments, the CMC material may be formed as, e.g., a carbon fiber cloth rather than as a tape. Additionally, or alternatively, the CMC material may be formed in any other suitable manner or using any other suitable materials. Referring still toFIG.3, and as is discussed above and further below, the combustion gases66flow from the combustion chamber114into and through the turbine section of the propulsion system10, where a portion of thermal and/or kinetic energy from the combustion gases66is extracted via sequential stages of turbine stator vanes and turbine rotor blades within the HP turbine28and LP turbine30. More specifically, as is depicted inFIG.3, combustion gases66from the combustion chamber114flow into the HP turbine28, located immediately downstream of the combustion chamber114, where thermal and/or kinetic energy from the combustion gases66is extracted via sequential stages of HP turbine stator vanes68and HP turbine rotor blades70. As is also discussed above with reference toFIG.2, the HP turbine28is coupled to the HP compressor24via the HP shaft34to form a HP spool or HP rotor operable to maximum speeds generally higher than an LP spool formed by the LP compressor22, the LP turbine30, the LP shaft36, and the fan section14. Accordingly, rotation of the plurality of stages of HP turbine rotor blades70correspondingly rotates a plurality of stages of HP compressor rotor blades80. The exemplary propulsion system10ofFIGS.2-3are configured to be operated in order to maintain a temperature of the HP turbine28below a maximum operating temperature for the various components therein, with decreased cooling flow extracted from the compressor section. In a particular embodiment, the HP turbine includes one or more stages of blades formed as a substantially solid, impermeable at the airfoil at the core flowpath. In other embodiments, the HP turbine includes one or more stages of blades configured for decreased cooling flow therethrough, such as to improve engine efficiency by reducing or eliminating an amount of air removed from the thermodynamic cycle (i.e., air removed from combustion) via reducing or eliminating cooling flow from the compressor section to the HP turbine. Referring back toFIG.3, the turbine section includes an inter-turbine frame300positioned between the HP turbine28and the LP turbine30. The frame300is configured as a stationary, static support structure configured to support one or both of the HP turbine28or the LP turbine30. The frame300includes an inter-turbine burner310configured to allow a flow of gaseous fuel into the core flowpath upstream of the LP turbine. The frame forms the burner at a vane or strut312of the frame and one or more orifices or openings306configured to allow the flow of gaseous fuel362through the strut312into the core flowpath. In various embodiments, the inter-turbine burner310forms a second fuel conduit configured to deliver the gaseous fuel362to the core flowpath. In a particular embodiment, the burner310is formed as a flameholder at the strut312of the frame300, in contrast to a combustion system such as formed at the combustion section. In certain embodiments, the inter-turbine burner includes struts or vanes formed as airfoils and/or structural members, such as generally provided for inter-turbine frames, midframe structures, or other support frames. The strut312includes a forward or leading edge304and an aft or trailing edge302. The struts312include hollow portions to allow for fluid flow therethrough. In certain embodiments, the frame300includes a lubricant conduit316and an air conduit314such as generally provided for lubricants or air for a bearing assembly320. The inter-turbine frame300may further include a conduit308configured to egress a flow of gaseous fuel362through the orifice306at the strut312. In a particular embodiment, the orifice306is positioned at the trailing edge302of the strut312, such as to allow the gaseous fuel to flow therethrough and aft toward the LP turbine30. The combustion section26is configured as a deflagrative or detonative combustion section. A flow of liquid fuel352is provided to the combustion section26through one or more fuel nozzles124. The flow of liquid fuel352is mixed with compressed air from the compressor section then burned to generate combustion gases66. The liquid fuel352provided to the combustion section26is a liquid jet fuel or aviation turbine fuel, such as a kerosene-based fuel, naphtha-type fuels, or equivalent (e.g., Jet-A, Jet-B, Jet Propellant (JP8), biofuels, synthetic fuels, or other appropriate aviation fuel). The gaseous fuel362provided to the inter-turbine burner is a gaseous fuel, such as hydrogen gas (H2), natural gas, methane, synthesis gas, or other appropriate type of gaseous fuel. The flow of gaseous fuel362released through the inter-turbine burner310between the HP turbine28and the LP turbine30is mixed with the flow of combustion gases66. It should be appreciated that the gaseous fuel362has a gaseous fuel ignition temperature (i.e., a second ignition temperature) less than a liquid fuel ignition temperature (i.e., a first ignition temperature) of the liquid fuel352. The gaseous fuel362further has a gaseous fuel burning velocity (i.e., a second burning velocity) greater than a liquid fuel burning velocity (i.e., a first burning velocity) of the liquid fuel352. The relatively lower second ignition temperature limit allows the mixture of gaseous fuel362from the inter-turbine burner310and the combustion gases66from the combustion section26to generate the second combustion gases with the relatively high-speed flow of fluid through the turbine section. The second combustion gases produced by the inter-turbine burner310may further have a flame speed greater than that of the first combustion gases produced by the combustion section26. In certain embodiments, the gaseous fuel362has an upper flammability limit greater than the liquid fuel. In still certain embodiments, additionally, the range of the flammability limit is generally greater than that of the liquid fuel. In certain embodiments, the lower flammability limit of the gaseous fuel is lower than the upper flammability limit of the liquid fuel. Still further, the gaseous fuel has a higher degree or magnitude of flammability than the liquid fuel. Accordingly, the mixture of gaseous fuel and combustion gases may burn without external ignition (e.g., with an igniter or other energy input), unlike afterburner systems utilizing liquid fuel. The aircraft100and propulsion system10, separately or together, include a first fuel system350for flowing and distributing the liquid fuel352at the combustion section26and a second fuel system360for flowing and distributing the gaseous fuel362at the inter-turbine burner310. It should be appreciated that the first fuel system350may further be configured to provide the liquid fuel352as an actuation fluid and/or a heat exchange fluid (e.g., to receive heat or thermal energy from another fluid or surface), in contrast to the second fuel system360. More particularly, the first fuel system350may be configured to provide actuation force or pressure to modulate one or more valves, actuators, doors, openings, nozzles, flow devices, or adjustable areas at the propulsion system, such as variable area nozzles, bleed valves, exhaust nozzles, active clearance control valves or doors, transient or start bleed valves, or other actuatable portion of the propulsion system or aircraft. Embodiments of the aircraft100and propulsion system10depicted and described herein may provide improved propulsion system and aircraft efficiency, emissions, or fuel burn. The inter-turbine burner310can increase LP turbine30power extraction over a given high pressure (HP) spool or core engine size (i.e., the HP compressor24, the combustion section26, and the HP turbine38). The second fuel system360configured to provide gaseous fuel362to the inter-turbine burner310separate from the first fuel system350configured to provide liquid fuel352to the combustion section26allows for increased LP turbine power extraction and power output greater than the power output from the core engine alone. It should be appreciated that, although described as an inter-turbine burner between an HP turbine and an LP turbine, various embodiments provided herein may include the inter-turbine burner between a first turbine receiving higher pressure combustion gases and a second turbine receiving lower pressure combustion gases. As such, various embodiments may include an intermediate pressure (IP) turbine generally positioned between the HP turbine and the LP turbine. Particular embodiments may position the inter-turbine burner described herein between the HP turbine and the IP turbine, or between the IP turbine and the LP turbine. Still further, although depicted as a conventional turbine rotor, embodiments of the HP turbine or LP turbine provided herein may be configured as interdigitated or vaneless turbine assemblies. Embodiments of the aircraft100and propulsion system10provided herein allow for sizing and operating the core engine at a steady-state speed and power output particularly for hybrid-electric propulsion systems and/or obviating power generation from a separate auxiliary power unit (APU). In certain embodiments, the propulsion system10is configured to generate a work-split between the core engine including the high pressure (HP) spool and combustion section versus the low pressure (LP) spool including the inter-turbine burner. In various embodiments, the propulsion system10has a rated power output ratio of the core engine and the inter-turbine burner310with the LP spool (i.e., the LP turbine30, the LP compressor22, and the fan section14) between 1.5 and 5.7. In certain embodiments, the propulsion system is configured to generate an 85/15 work-split between the core engine and the LP spool. Stated differently, the core engine is configured to operate the HP spool at a maximum rotational speed corresponding to 85% of the rated power output of the propulsion system10. The propulsion system10is further configured to generate up to 15% of the rated power output of the propulsion system via the LP spool and inter-turbine burner using the gaseous fuel and combustion gases generated from the core engine. Such ratios may allow for substantially reduced heat loads from the combustion section26imparted onto the downstream turbine components, which may allow for improved durability and reduced cooling flow, which may improve overall propulsion system efficiency. In another embodiment, the propulsion system is configured to generate an 80/20 work-split between the core engine and the LP spool and the inter-turbine burner. In still another embodiment, the propulsion system is configured to generate a 75/25 work-split between the core engine and the LP spool and the inter-turbine burner. In still yet another embodiment, the propulsion system is configured to generate a 60/40 work-split between the core engine and the LP spool and the inter-turbine burner. In still various embodiments, the propulsion system is configured to generate between 60% and 85% of the maximum power output through combustion gases generated via the core engine, and the remainder via the LP spool and inter-turbine burner using the gaseous fuel and combustion gases generated from the core engine. In various embodiments, the work-split is between a low-power output versus a remaining difference from the maximum power output. Stated differently, the work-split is a limit between a low-power output operating condition, above which (via the inter-turbine burner and flow of gaseous fuel) the operating condition is a high-power output condition. In certain embodiments, the maximum power output is particularly a rated power output with reference to a maximum rotational speed of the propulsion system while operating properly. For example, the propulsion system may be operating at the rated speed or rated power output during maximum load operations, such as during takeoff operation with regard to a landing-takeoff (LTO) cycle. In certain embodiments, the limit or delineation of the work-split (e.g., 60%-85% generally, such as 85%, or 80%, or 75%, or 60%) of the maximum power output corresponds to a cruise or descent operation of the propulsion system and aircraft relative to the LTO cycle versus a difference from the rated power output of the propulsion system. As such, certain embodiments of the propulsion system are configured for maximum rotational speed from operation of only first fuel system providing the liquid fuel (i.e., without operation of the inter-turbine burner) to the core engine corresponding to a cruise condition. In still certain embodiments, the propulsion system is configured for maximum power output or rated power output from operation of both of the combustion section with the first fuel system and the inter-turbine burner with the second fuel system. It should be appreciated that those skilled in the art understand that ranges and ratios of work-split provided herein correspond to particular structures and sizes of the core engine, inter-turbine burner, and the LP spool. Typical aircraft gas turbine propulsion engines are designed, sized, and structured to generate 100% of the maximum power output via combustion gases generated at the combustion section and extracted via the LP spool. Certain aircraft gas turbine propulsion engines utilize afterburner or reheat systems configured to utilize a portion of the liquid fuel, typically directed to a main burner at the combustion section, and mixed with combustion gases downstream of the main burner to further generate thrust (i.e., afterburner). However, such typical afterburning systems are generally unsuitable for commercial aircraft or other aircraft restricted by emissions output. Additionally, such systems utilizing liquid fuel are generally complex, having an igniter system and complications related to the lower flammability of liquid fuel. Such systems may generally produce levels of emissions, smoke, or noise that may prohibit utilization with commercial aircraft. Referring back toFIG.2, the propulsion system10may further include a computing system210configured to operate the propulsion system10such as described herein. The computing system210can correspond to any suitable processor-based device, including one or more computing devices, such as described above. In certain embodiments, the computing system210is a full-authority digital engine controller (FADEC) for a gas turbine engine, or other computing module or controller configured to execute instructions for operating a gas turbine engine. For instance,FIG.6illustrates one embodiment of suitable components that can be included within the computing system210. The computing system210can include a processor212and associated memory214configured to perform a variety of computer-implemented functions. As shown, the computing system210can include control logic216stored in memory214. The control logic216may include instructions that when executed by the one or more processors212cause the one or more processors212to perform operations. Additionally, the computing system210can also include a communications interface module230. In several embodiments, the communications interface module230can include associated electronic circuitry that is used to send and receive data. As such, the communications interface module230of the computing system210can be used to send and/or receive data to/from propulsion system10. In addition, the communications interface module230can also be used to communicate with any other suitable components of the propulsion system10, such as described herein. It should be appreciated that the communications interface module230can be any combination of suitable wired and/or wireless communications interfaces and, thus, can be communicatively coupled to one or more components of the power generation system via a wired and/or wireless connection or distributed network. The communications interface module230can include any suitable wired and/or wireless communication links for transmission of the communications and/or data, as described herein. For instance, the module230can include a SATCOM network, ACARS network, ARINC network, SITA network, AVICOM network, a VHF network, a HF network, a Wi-Fi network, a WiMAX network, a gatelink network, etc. A method for operating a propulsion system for an aircraft is provided (hereinafter “method1000”). The method may be executed with an aircraft and propulsion system such as described above, or other appropriate system. In particular embodiments, the method1000is executable with the computing system210of the propulsion system10or aircraft100, such as a computer-implemented method. It should be appreciated that the computing system210and the method1000provided herein may allow for improved propulsive efficiency, decreased emissions output, and overall improvement in engine and aircraft operation. Certain embodiments may provide benefits particular to propulsion systems and aircraft under restrictions with regard to emissions output, noise, or thrust. The method1000includes at1010flowing liquid fuel to a combustion section of the propulsion system. The method1000at1020includes generating first combustion gases at the combustion section corresponding to 85% or less of a rated power output of the propulsion system. The method1000at1030includes modulating rotational speed of the LP spool via modulating a flow of gaseous fuel to an inter-turbine burner to generate second combustion gases, such as depicted and described herein. In various embodiments, the method1000includes at1022operating a core engine and a low pressure (LP) spool with an inter-turbine burner at a rated power output ratio of the core engine and the inter-turbine burner with the LP spool between 1.5 and 5.7, such as described above. In a particular embodiment, the method1000includes at1024operating a high pressure (HP) spool at a maximum rotational speed corresponding to between 60% and 85% of the rated power output of the propulsion system. The method1000at1026includes flowing gaseous fuel to the inter-turbine burner to generate the rated power output of the propulsion system. As such, the method1000may have the engine operate at a substantially steady-state operating condition via the flow of liquid fuel up to 60% to 85% of the rated power output, and the method1000may have the engine modulate the flow of gaseous fuel to generate the remainder of the rated power output, or portions thereof. In certain embodiments, the method1000includes at1040operating a high pressure (HP) spool at a steady-state rotational speed while modulating the flow of gaseous fuel to the inter-turbine burner. In certain embodiments, the operations include at1042receiving a control signal corresponding to a high-power operating mode of the propulsion system. In some embodiments, receiving the control signal corresponding to the high-power operating mode includes a rated power operation or takeoff operating mode of the propulsion system. In other embodiments, the high-power operating mode corresponds to a climb, descent or approach, or takeoff condition relative to the LTO cycle. The method1000at1044includes flowing gaseous fuel to the inter-turbine burner to generate the second combustion gases corresponding to a difference between the rated power output of the propulsion system and a power output generated by flowing liquid fuel to the combustion section. In another embodiment, the method1000includes at1046receiving a control signal corresponding to a low-power operating mode of the propulsion system. In a particular embodiment, the low-power operating mode corresponds to a cruise condition relative to the LTO cycle. The method1000at1048includes decreasing the flow of gaseous fuel to the inter-turbine burner to decrease the power output of the propulsion system. In a particular embodiment, the method1000at1050includes operating a high pressure (HP) spool at a steady-state rotational speed while decreasing the flow of gaseous fuel to the inter-turbine burner. In a still particular embodiment, decreasing the flow of gaseous fuel to the inter-turbine burner to decrease the power output of the propulsion system corresponds to changing the operating mode of the propulsion system from a high-power operating mode to a low-power operating mode. It should be appreciated that those skilled in the art will understand the elapsed time and tolerances, ranges, or deviations of a given speed or power output corresponding to “steady-state” operating condition. In particular embodiments, those skilled in the art will understand “steady-state’ within the context of aviation propulsion systems. In still particular embodiments, those skilled in the art will understand “steady-state”, speeds, or power outputs provided herein within the context of a landing-takeoff cycle for an aircraft. It should be appreciated that embodiments of the propulsion system10, aircraft100, and method1000provided herein include combinations of elements, subsystems, arrangements, and configurations that provide unexpected benefits over known elements separately or in known arrangements and configurations. For instance, it should be appreciated that having separate fuel systems and methods for control, such as via the first fuel system350and the second fuel system360, and the method1000provided herein, introduces elements that prior to now may be perceived as additionally complicated or complex, such as to discourage implementation into certain propulsion systems and aircraft, such as commercial or general aviation aircraft. However, as provided herein, the present disclosure describes systems, methods, and particular combinations or arrangements that provide unexpected benefits outweighing complexities associated with separate fuel systems. Such benefits include allowing substantially steady-state rotational speed or operation of the HP spool while increasing and decreasing power output of the propulsion system. Such benefit may allow for operating one or more propulsion systems of the aircraft to generate electric power to aircraft subsystems while at idle operating conditions, runway taxiing or gate-side operation, or other instances at which known aircraft propulsion systems may not operate due to higher fuel consumption in contrast to using an auxiliary power unit (APU) to generate electric energy for an aircraft or other propulsion systems. As such, embodiments of the propulsion system and engine provided herein may obviate the need or desire for an APU in an aircraft, such as to reduce aircraft weight and improve aircraft efficiency. Such benefits may also include allowing the core engine to be a smaller size and less fuel consumption to generate the rated power output of a known propulsion system with a relatively larger core engine. Embodiments provided herein allow for the core engine of the propulsion system to perform operations more typical of APUs and unlike those typically performed for aircraft propulsion systems. Additionally, embodiments provided herein allow for improved emissions output over known propulsion systems, such as via the reduced core engine size and the improved emissions output from gaseous fuel to generate rated power output at particular engine operating conditions. Still further, by providing for the second fuel system360and method1000for operation at particular operating conditions, issues related to gaseous fuel are mitigated in contrast to utilizing gaseous fuel for substantially all operating conditions. This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. Further aspects of the invention are provided by the subject matter of the following clauses:1. An aircraft propulsion system, the propulsion system including a low pressure (LP) spool comprising a fan section, a LP compressor, and an LP turbine; a core engine comprising a high pressure (HP) compressor, a combustion section, and an HP turbine, wherein the HP compressor and the HP turbine together form a rotatable HP spool; a frame positioned in serial flow arrangement between the HP turbine and the LP turbine, wherein the frame comprises an inter-turbine burner comprising a strut forming an outlet opening into a core flowpath of the propulsion system; a first fuel system comprising a first fuel conduit in fluid communication with a fuel nozzle at the combustion section, wherein the first fuel system is configured to flow a liquid fuel to the combustion section for generating first combustion gases; a second fuel system comprising a second fuel conduit in fluid communication with the core flowpath via the outlet opening at the inter-turbine burner, wherein the second fuel system is configured to flow a gaseous fuel to the core flowpath for generating second combustion gases; wherein the LP compressor, the HP compressor, the combustion section, the HP turbine, the inter-turbine burner, and the LP turbine are in serial flow arrangement; and wherein the propulsion system comprises a rated power output ratio of the core engine and the inter-turbine burner with the LP spool between 1.5 and 5.7.2. The propulsion system of any one or more clauses herein, wherein the core engine is configured to operate the HP spool at a maximum rotational speed corresponding to between 60% and 85% of the rated power output of the propulsion system.3. The propulsion system of any one or more clauses herein, the propulsion system comprising a computing system comprising a processor and memory, wherein the memory is configured to store instructions that, when executed by the processor, cause the propulsion system to perform operations, the operations comprising flowing liquid fuel to the combustion section then generating first combustion gases at the combustion section corresponding to 85% or less of the rated power output of the propulsion system.4. The propulsion system of any one or more clauses herein, the operations comprising modulating rotational speed of the LP spool via modulating the flow of gaseous fuel to the inter-turbine burner to generate the second combustion gases.5. The propulsion system of any one or more clauses herein, the operations comprising operating the HP spool at a steady-state rotational speed while modulating the flow of gaseous fuel to the inter-turbine burner.6. The propulsion system of any one or more clauses herein, the operations comprising modulating a flow of gaseous fuel through the inter-turbine burner to alter an output power of the propulsion system.7. The propulsion system of any one or more clauses herein, the operations comprising maintaining a steady-state rotational speed of the HP spool when modulating the flow of gaseous fuel.8. The propulsion system of any one or more clauses herein, the operations comprising receiving a control signal corresponding to a high-power operating mode of the propulsion system; then flowing gaseous fuel to the inter-turbine burner to generate the second combustion gases corresponding to a difference between the rated power output of the propulsion system and a power output generated by flowing liquid fuel to the combustion section.9. The propulsion system of any one or more clauses herein, the operations comprising receiving a control signal corresponding to a low-power operating mode of the propulsion system; then decreasing the flow of gaseous fuel to the inter-turbine burner to decrease the power output of the propulsion system.10. The propulsion system of any one or more clauses herein, the operations comprising operating the HP spool at a steady-state rotational speed while decreasing the flow of gaseous fuel to the inter-turbine burner.11. The propulsion system of any one or more clauses herein, wherein the fan section is configured as an unducted open rotor.12. The propulsion system of any one or more clauses herein, the propulsion system comprising an electric machine operably coupled to the HP spool.13. A computing system for an aircraft propulsion system, the computing system comprising one or more processors and one or more memory, wherein the memory is configured to store instructions that, when executed by the processor, cause the propulsion system to perform operations, the operations comprising flowing liquid fuel to a combustion section of the propulsion system; generating first combustion gases at the combustion section corresponding to 85% or less of a rated power output of the propulsion system; and modulating rotational speed of the LP spool via modulating a flow of gaseous fuel to an inter-turbine burner to generate second combustion gases.14. The computing system of any one or more clauses herein, the operations comprising operating a high pressure (HP) spool at a steady-state rotational speed while modulating the flow of gaseous fuel to the inter-turbine burner.15. The computing system of any one or more clauses herein, the operations comprising the operations comprising receiving a control signal corresponding to a high-power operating mode of the propulsion system; and flowing gaseous fuel to the inter-turbine burner to generate the second combustion gases corresponding to a difference between the rated power output of the propulsion system and a power output generated by flowing liquid fuel to the combustion section.16. The computing system of any one or more clauses herein, the operations comprising receiving a control signal corresponding to a low-power operating mode of the propulsion system; and decreasing the flow of gaseous fuel to the inter-turbine burner to decrease the power output of the propulsion system.17. The computing system of any one or more clauses herein, the operations comprising operating a high pressure (HP) spool at a steady-state rotational speed while decreasing the flow of gaseous fuel to the inter-turbine burner.18. The computing system of any one or more clauses herein, the operations comprising operating a core engine and a low pressure (LP) spool with an inter-turbine burner at a rated power output ratio of the core engine and the inter-turbine burner with the LP spool between 1.5 and 5.7.19. The computing system of any one or more clauses herein, the operations comprising operating a high pressure (HP) spool at a maximum rotational speed corresponding to between 60% and 85% of the rated power output of the propulsion system.20. The computing system of any one or more clauses herein, the operations comprising flowing gaseous fuel to the inter-turbine burner to generate the rated power output of the propulsion system.21. The propulsion system of any one or more clauses herein, comprising the computing system of any one or more clauses herein,22. The computing system of any one or more clauses herein, configured to operate the propulsion system of any one or more clauses herein.23. An aircraft comprising the propulsion system of any one or more clauses herein.24. An aircraft comprising the computing system of any one or more clauses herein. | 51,110 |
11859542 | DETAILED DESCRIPTION The disclosure includes a system using a turbine engine to generate one or more thrusts (e.g., vertical and/or forward thrusts) on an aircraft body. The turbine engine is configured to combust a fuel to mechanically rotate a turbine rotor and generate an engine air flow through the turbine engine, as well as power other mechanical loads carried on the aircraft frame. The engine air flow or some portion thereof may be exhausted through a jet nozzle to generate an engine thrust on the aircraft body to, for example, provide forward airspeed to allow the aircraft wings to generate sufficient lift to support conventional airborne flight. The system may be configured to generate one or more additional thrusts (e.g., vertical thrusts) using one or more lift fans to act on the aircraft body simultaneously with or separately from the engine thrust. The system includes a plurality of lift fans powered by the turbine engine. A lift fan may include a plurality of vanes configured to rotate to generate a directed air flow (e.g., in a downward direction), causing an oppositely oriented thrust (e.g., an upward and/or vertical thrust) on the aircraft body. The plurality of lift fans may include one or more shaft-driven lift fans powered by shaft power withdrawn from the rotor of the turbine engine, and may include one or more gas-driven lift fans powered by some portion of the air flow flowing through the turbine engine. The system may be configured to generate the thrusts on the aircraft body using only the one or more of the lift fans (e.g., in a vertical take-off or hover mode), using only the jet nozzle (e.g., in a conventional take-off or conventional flight mode), or using both one or more of the lift fans and the jet nozzle (e.g., in a short take-off or low speed cruise mode). In examples, the turbine engine configured to combust a fuel to cause rotation of a turbine rotor to produce shaft power. The turbine engine may be configured to use some portion of the shaft power to generate an engine air flow (e.g., using the rotation of fan blades) through the turbine engine. In examples, the turbine engine is configured to selectively direct at least some portion of the engine airflow through a jet nozzle to cause engine thrust on the turbine engine and the aircraft body. The system is further configured to transfer power from the turbine engine to the shaft-driven lift fan and/or the gas-driven lift fan, such that the shaft-driven lift fan may provide a first thrust on the aircraft body and/or the gas-driven lift fan may provide a second thrust to the aircraft body. The system may be configured to cause the first thrust and/or the second thrust instead of or in addition to the engine thrust. In examples, the shaft-driven lift fan is configured to provide the first thrust as a vertical thrust acting on the aircraft body to at least partially counteract a gravity vector acting on the aircraft body. The gas-driven lift fan may be configured to provide the second thrust as a vertical thrust acting on the aircraft body to at least partially counteract the gravity vector acting on the aircraft body. The one or more shaft-driven lift fans may be configured to generate the first thrust on the aircraft body using rotor power transferred from the turbine rotor, wherein the rotor power is a portion of the shaft power generated. In some examples, a shaft-driven lift fan may be configured to receive the rotor power from a gearbox configured to transmit the rotor power from the turbine engine to a shaft of the shaft-driven lift fan. In some examples, a shaft-driven lift fan is configured to receive electrical power from a generator driven by the rotor power. The one or more gas-driven lift fans may be configured to generate the second thrust using a gas flow, wherein the gas flow is a portion of the engine air flow. In examples, the gas-driven lift fan is configured to convert a flow energy (e.g., a kinetic energy, potential energy, and/or internal energy) of the gas flow into a rotary motion of a plurality of vanes. For example, the gas-driven lift fan may be a tip-turbine fan including one or more turbine blades configured to rotate the plurality of vanes when the gas flow impinges on the one or more turbine blades. The system may provide advantage over aircraft lift fan systems which use only electrically powered fans receiving electrical power generated by one or more turbines and/or mechanically powered fans receiving mechanical power generated by one or more turbines. Such systems may suffer a decrease in efficiency by exhausting at least some portion of the energy generated by a turbine as a relatively high velocity exhaust flow with limited contribution to the production of vertical thrust on the aircraft. The gas-driven lift fan employed herein may more effectively employ the flow energy that might otherwise be expended as exhaust flow by utilizing the flow energy for the rotation of the gas-driven lift fan. The system is configured such that the turbine engine may generate shaft power to provide the rotor power to drive the shaft-driven lift fan while generating engine air flow to provide the gas flow to drive the gas-driven lift fan, such that the turbine engine may concurrently use both shaft power and engine air flow to provide vertical thrust to the aircraft body. In examples, the system includes control circuitry configured to determine a first power requirement required by the shaft-driven lift fan to provide the first thrust. The control circuitry may be configured to determine a second power requirement required by the gas-driven lift fan to provide the second thrust. The control circuitry may be configured to control a throttle controlling the flow of fuel to the turbine engine based on at least the first power requirement and the second power requirement. In examples, the control circuitry is configured to determine the flow of fuel required for the turbine engine to satisfy at least the first power requirement and the second power requirement. For example, the control circuitry may be configured to determine the flow of fuel required based on the first power requirement, the second power requirement, a third power requirement required to provide an engine thrust, and additional power requirements required to power other operating loads (e.g., generators, pumps, gearboxes, boost compressors, an ECS, a control surface conditioning system, a fuel tank pressurization system, other service air systems, and other loads operating onboard the aircraft). Hence, the control circuitry may be configured to provide the fuel such that operations of the turbine engine sustainably support the shaft power withdrawn from the turbine engine (e.g., the first power requirement) and the flow energy supplied by the withdrawn gas flow (e.g., the second power requirement). In examples, the control circuitry may be configured to determine at least the first power requirement and the second power requirement. The control circuitry may be configured to determine at least the first power requirement and the second power requirement based on a attitude of the aircraft body. The attitude may be, for example, an orientation of the aircraft body with respect to one or more reference axes (e.g., a gravity vector) having an orientation substantially independent from the attitude of the aircraft body. In some examples, the control circuitry is configured to receive a signal indicative of a current attitude and/or desired attitude from an attitude control system. The control circuitry may be configured to determine at least the first power requirement and the second power requirement based on the indicative signal from the attitude control system. As used herein, a thrust on the aircraft body may mean a force acting on the aircraft body which tends to produce motion of the aircraft body through a spatial coordinate system and/or counteracts a gravity force acting on the aircraft body. In examples, a lift fan (e.g., a shaft-driven lift fan and/or a gas-driven lift fan) is configured to generate a flow of air such that the flow of air causes a reaction force (e.g., a first thrust or second thrust) on the lift fan. The lift fan may be configured to transmit the thrust to the aircraft body to produce motion of the aircraft body through a spatial coordinate system and/or counteract a gravity force acting on the aircraft body. In examples, the turbine engine is configured to generate a flow of air such that the flow of air causes a reaction force (e.g., an engine thrust) on the turbine engine. The turbine engine may be configured to transmit the engine thrust to the aircraft body to produce motion of the aircraft body through a spatial coordinate system and/or counteract a gravity force acting on the aircraft body. As used herein, an engine air flow may mean an air flow drawn into the turbine engine (e.g., by an intake fan) and passing through at least some portion of a housing (e.g., a pod and/or cowling) of the turbine engine. FIG.1illustrates a perspective drawing of an example system100including a turbine engine102configured to provide power to a shaft-driven lift fan104and a gas-driven lift fan106. Turbine engine102, shaft-driven lift fan104, and gas-driven lift fan106may be mechanically supported by an aircraft body108of an aircraft110.FIG.1illustrates aircraft body108as a general profile for clarity and further illustrates principal axes of aircraft body108, including a longitudinal axis LON, a lateral axis LAT orthogonal to the axis LON, and a vertical axis V orthogonal to the axes LON and LAT. Turbine engine102is configured to combust a fuel to generate a shaft power (e.g., a rotary power) using turbine rotor112and generate an engine air flow EAF within turbine engine102(e.g., via intake section114). Shaft-driven lift fan104is configured to generate a first thrust using rotor power generated by turbine engine102, where the rotor power is a portion of the shaft power. Gas-driven lift fan106is configured to generate a second thrust using a gas flow provided by turbine engine102, wherein the gas flow is a portion of engine air flow EAF. Turbine engine102may be configured to provide an engine thrust using an exhaust air flow EXF (e.g., via a jet nozzle116), wherein exhaust air flow EXF is another portion of engine air flow EAF. In examples, turbine engine102is configured to cause exhaust air flow EXF to exit jet nozzle116through an outlet area AE defined by a boundary of j et nozzle116. In examples, turbine engine102is configured to vary the outlet area AE by adjusting a configuration of jet nozzle116. Turbine engine102may be configured to vary the outlet area AE to, for example, vary the engine thrust provided by turbine engine102, vary a pressure of engine air flow EAF within turbine engine102, or for other reasons. In examples, aircraft body108mechanically supports turbine engine102such that a housing103of turbine engine102is substantially stationary relative to the axes LON, LAT and V. Shaft-driven lift fan104and/or gas-driven lift fan106may be located anywhere on aircraft body108. One or more gas-driven fans (e.g., gas-driven fan106) may be located relative to one or more shaft-driven fans (e.g., shaft-driven fan104) in any direction on aircraft body108. In some examples, one or more gas-driven fans (e.g., gas-driven fan106) may be located substantially aft of one or more shaft-driven fans (e.g., shaft-driven fan104) on aircraft body108(e.g., displaced in an aft direction from one or more shaft-driven fans). For example, gas-driven fan106may be located aft of shaft-driven fan104to provide a more direct flow path for a gas flow provided to gas-driven fan106from turbine engine102. As used here, an aft direction may mean a direction from a front portion115of aircraft body108toward a rear section of aircraft body108. A forward direction may mean a direction from rear portion117of aircraft body108toward front section115of aircraft body108. Shaft-driven lift fan104may be configured to generate the first thrust, gas-driven lift fan106may be configured to generate the second thrust, and turbine engine102may be configured to generate the engine thrust to act on aircraft body108in any direction relative to the axis LON, the axis LAT, and the axis V. In examples, shaft-driven lift fan104is configured such that at least a component of the first thrust generated acts on aircraft body108in a direction substantially parallel to the axis V (e.g., to counteract a gravity vector acting on aircraft body108). Gas-driven lift fan106may be configured such that at least a component of the second thrust generated acts on aircraft body108in a direction substantially parallel to the axis V (e.g., to counteract a gravity vector acting on aircraft body108). Turbine engine102may be configured such that at least a component of the engine thrust generated acts on aircraft body108in a direction substantially parallel to the axis LON. Aircraft body108includes one or more wings such as wing109configured to generate lift on aircraft body108when turbine engine102, shaft-driven lift fan104, and/or gas-driven lift fan106provide thrust substantially parallel to the axis LON (e.g., in a forward direction of aircraft body108). In examples, shaft-driven lift fan104is configured to produce a first air flow AF1 using the rotor power provided by turbine engine102. Shaft-driven lift fan104may be configured such that air flow AF1 causes a reaction force (e.g., the first thrust) on shaft-driven lift fan104when shaft-driven lift fan104produces air flow AF1. Shaft-driven lift fan104may be configured to transmit at least some portion of the first thrust to aircraft body108. In examples, shaft-driven lift fan104is configured to produce air flow AF1 is a direction substantially away from aircraft body108to provide the first thrust acting toward aircraft body108. Shaft-driven lift fan104may be configured (e.g., steerable by a control system and/or an operator) to produce air flow AF1 in any direction relative to the axes LAT, LON, and/or V. In examples, shaft-driven lift fan104is configured to produce air flow AF1 such that at least some portion of air flow AF1 flows in a direction substantially parallel to the axis V (e.g., in a downward direction relative to aircraft body108), such that shaft-driven lift fan104provides the first thrust acting in a substantially opposite direction on aircraft body108(e.g., in an upward direction relative to aircraft body108). In examples, gas-driven lift fan106is configured to produce a second air flow AF2 using the gas flow provided by turbine engine102. Shaft-driven lift fan104may be configured such that air flow AF2 causes a reaction force (e.g., the second thrust) on gas-driven lift fan106when gas-driven lift fan106produces air flow AF2. Gas-driven lift fan106may be configured to transmit at least some portion of the second thrust to aircraft body108. Gas-driven lift fan106may be configured (e.g., steerable by a control system and/or an operator) to produce air flow AF2 in any direction relative to the axes LAT, LON, and/or V. In examples, gas-driven lift fan106is configured to produce air flow AF2 is a direction substantially away from aircraft body108to provide the second thrust acting toward aircraft body108. In examples, gas-driven lift fan106is configured to produce air flow AF2 such that at least some portion of air flow AF2 flows in a direction substantially parallel to the axis V (e.g., in a downward direction relative to aircraft body108), such that gas-driven lift fan106provides the second thrust acting in a substantially opposite direction on aircraft body108(e.g., in an upward direction relative to aircraft body108). Gas-driven lift fan106may be configured to be steered independently of and/or in a different direction from shaft-driven lift fan104, and vice-versa, such that, for example, shaft-driven lift fan104may generate the air flow AF1 in a first direction and gas-driven lift fan106may generate the air flow AF2 in a second direction different from the first direction. Turbine engine102may be configured may be configured such that exhaust air flow EXF causes a reaction force (e.g., the engine thrust) on turbine engine102when turbine engine102produces exhaust air flow EXF. Turbine engine102may be configured to transmit at least some portion of the engine thrust to aircraft body108. Turbine engine102may be configured to produce exhaust air flow EXF is a direction substantially away from aircraft body108to provide the engine thrust acting toward aircraft body108. Turbine engine102may be configured (e.g., have a component such as jet nozzle116steerable by a control system and/or an operator) to produce exhaust air flow EXF in any direction relative to the axes LAT, LON, and/or V. In examples, turbine engine102is configured to produce exhaust air flow EXG such that at least some portion of exhaust air flow EXF flows in a direction substantially parallel to the axes LON (e.g., in an aft direction relative to aircraft body108), such that turbine engine102provides the engine thrust acting in a substantially opposite direction on aircraft body108(e.g., in a forward direction relative to aircraft body108). Turbine engine102(e.g., jet nozzle116) may be configured to be steered independently of and/or in a different direction from shaft-driven lift fan104and/or gas-driven lift fan106, and vice-versa, such that, for example, turbine engine102may generate exhaust air flow EXF in a third direction different from the first direction of air flow AF1 produced by shaft-driven lift fan104and different from the second direction of air flow AF2 produced by gas-driven lift fan106. In examples, shaft-driven lift fan104may be configured to receive the rotor power transferred from turbine engine102via a transmission system118operably coupled to turbine engine102(e.g., turbine rotor112). The gearbox of transmission system118may be configured to receive the rotor power produced by turbine engine102as an input torque and provide at least some portion of the rotor power to shaft-driven lift fan104as an output torque, such that shaft-driven lift fan104may provide the first thrust using the rotor power. In some examples, transmission system118includes a generator (e.g., an AC generator or DC generator) configured to receive the rotor power from turbine engine102and generate electrical power. For example, the generator may include a generator rotor configured to rotate using the rotor power to generate the electrical power. Transmission system118may be configured to provide some portion of the electrical power to a motor of shaft-driven lift fan104, such that shaft-driven lift fan104may provide the first thrust using the rotor power. In examples, system100is configured to control transmission system118to substantially control and/or determine a magnitude of the first thrust produced by shaft-driven lift fan104. For example, system100may be configured to control the input torque provided to a gearbox of transmission system118(e.g., using a clutch and/or another component). System100may be configured to control the electrical power generated by a generator of transmission system118(by controlling a field of the generator, a rotation of the generator rotor, or some other parameter of the generator). Turbine engine102may be configured to provide the gas flow to gas-driven lift fan106via a duct120. Duct120may be configured to fluidically couple turbine engine102and gas-driven lift fan106, such that turbine engine102may provide some portion of engine air flow EAF (e.g., the gas flow) to gas-driven lift fan106. In examples, turbine engine102is configured to divert at least a portion of engine air flow EAF to duct120to provide the gas flow. For example, turbine engine102may include a diverter valve122configured to divert the portion of engine air flow EAF, such that the portion of engine air flow EAF flows into duct120rather than exhausting through jet nozzle116as exhaust air flow EXF. System100may be configured to substantially control and/or determine a magnitude of the second thrust produced by gas-driven lift fan106and a magnitude of the engine thrust produced by turbine engine102(e.g., using diverter valve122). For example, system100may control diverter valve122such that the second thrust produced by gas-driven lift fan106is greater than the engine thrust provided by turbine engine102(e.g., when aircraft110is in a slow speed cruise mode or hover mode). System100may control diverter valve122such that the second thrust produced by gas-driven lift fan106is less than the engine thrust provided by turbine engine102(e.g., when aircraft110is in a faster speed cruise mode or normal flight mode). System100may control diverter valve122such that gas-driven lift fan106produces the second thrust while turbine engine102produces substantially no engine thrust, and/or control diverter valve122such that turbine engine102produces the engine thrust while gas-driven lift fan106produces substantially no second thrust. In examples, system100includes control circuitry124configured to determine one or more of a first power requirement required by shaft-driven lift fan104to provide the first thrust, a second power requirement required by gas-driven lift fan106to provide the second thrust, and/or a third power requirement required by turbine engine102to provide the engine thrust. Control circuitry124may be configured to control the operation of turbine engine102based on the first power requirement, the second power requirement, or the third power requirement. For example, control circuitry124may be configured to control one or more of a throttle controlling the flow of fuel to turbine engine102, transmission system118, diverter valve122, and/or other components of system100which may impact the first thrust, second thrust, and/or engine thrust produced. Control circuitry124may be configured to control the throttle, transmission system118, diverter valve122, and/or the other components such that turbine engine102operates in a manner to substantially satisfy at least the first power requirement, the second power requirement, and/or the third power requirement. Control circuitry124may be configured to control the throttle, transmission system118, diverter valve122, and/or the other components such that turbine engine102operates in a manner to substantially satisfy additional power requirements required by other operating loads in addition to the first power requirement, the second power requirement, and/or the third power requirement, such as additional generators, pumps, additional gearboxes, boost compressors, an ECS, control surface conditioning systems, fuel tank pressurization systems, other service air systems, and other loads operating onboard the aircraft. Hence, control circuitry124may be configured to control the operation of turbine engine102such that turbine engine102sustainably supports the shaft power withdrawn from rotor112and the flow energy provided by engine air flow EAF to gas-driven lift fan106and/or jet nozzle116. Control circuitry124may be configured to determine at least the first power requirement, the second power requirement, and/or the third power requirement based on an attitude of aircraft body108. For example, system100may include attitude control circuitry126configured to determine an attitude of aircraft body108(e.g., an orientation of the axes LON, LAT, and/or V) with respect to one or more reference axes (e.g., a gravity vector) having an orientation substantially independent from the attitude of aircraft body108. In some examples, control circuitry124is configured to receive a signal indicative of a current attitude and/or desired attitude from attitude control circuitry126and determine at least the first power requirement, the second power requirement, and/or the third power requirement based at least in part on the indicative signal from attitude control circuitry126. In examples, control circuitry124is configured to determine at least the first power requirement, the second power requirement, and/or the third power requirement necessary to substantially achieve and/or substantially maintain an attitude of aircraft body108. For example, control circuitry124may be configured to determine at least the first power requirement, the second power requirement, and/or the third power requirement necessary to substantially achieve and/or and substantially maintain an specific orientation of the axes LON, LAT, and/or V with respect to the one or more reference axes. Control circuitry124may be configured to control the throttle, transmission system118, diverter valve122, and/or other components of aircraft110such that turbine engine102operates in a manner to substantially satisfy at least the first power requirement, the second power requirement, and/or the third power requirement necessary to substantially achieve and/or substantially maintain the specific orientation of the axes LON, LAT, and/or V with respect to the one or more reference axes. System100may include any number of turbine engines, any number of shaft-driven lift fans, and any number of gas-driven lift fans. In examples, system100includes at least a second turbine engine128. System100may include at least a second transmission system130, a second shaft-driven lift fan132, and a second duct134. Second turbine engine128, second transmission system130, second shaft-driven lift fan132, and second duct134may be configured similarly and in relation to each other in the same manner as turbine engine102, transmission system118, shaft-driven lift fan104, and duct120. Second turbine engine128may provide a second gas flow via second duct134to gas-driven lift fan106and/or to other gas-driven lift which may be present in system100. Second shaft-driven lift fan132may be configured to produce a third air flow AF3 using rotor power provided by second turbine engine128in substantially the same manner as that employed by shaft-driven lift fan104for the production of first air flow AF1 using the rotor power provided by turbine engine102. Shaft-driven lift fan104may be configured such that air flow AF1 causes a reaction force (e.g., the first thrust) on shaft-driven lift fan104when shaft-driven lift fan104produces air flow AF1. Second turbine engine228may be configured to provide an engine thrust using a second exhaust air flow EXF2 in substantially the same manner as that employed by turbine engine102for the production of exhaust air flow EXF. Second shaft-driven lift fan132may be configured to transmit at least some portion of a reaction force on second shaft-driven lift fan132caused by air flow AF3 to aircraft body108to produce a third thrust on aircraft body108. Second turbine engine128may be configured to transmit at least some portion of a reaction force on second turbine engine128caused by second exhaust air flow EXF2 to aircraft body108to produce a second engine thrust on aircraft body108. Control circuitry124may be configured to determine a power requirement required by second shaft-driven lift fan132to provide the third thrust, a power requirement required by gas-driven lift fan106to provide the second thrust, and/or a power requirement required by second turbine engine128to provide the second engine thrust. As will be discussed, control circuitry may be configured to control the operation of turbine engine102and/or second turbine engine128such that turbine engine102and/or second turbine engine128sustainably support the energy requirements of at least shaft-driven lift fan104for production of a first thrust, gas-driven lift fan106for production of a second thrust, second shaft-driven lift fan132from production of a third thrust, turbine engine102for production of an engine thrust, and/or second turbine engine128for production of a second engine thrust. FIG.2is a schematic illustration of system100in a first configuration with turbine engine102providing a thrust on aircraft body108(e.g., providing a forward thrust to support the generation of lift by wing109).FIG.3is a schematic illustration of system100in a second configuration with shaft-driven lift fan104provided a first thrust on aircraft body108and gas-driven lift fan providing a second thrust on aircraft body108. Turbine engine102is configured to combust a fuel to generate shaft power using turbine rotor112and generate engine air flow EAF within turbine engine102via intake section114. Turbine engine102may include an intake fan136, an engine core138, an exhaust section140, and jet nozzle116. Engine core138is configured to combust the fuel to produce a rotation of turbine rotor112. Engine core138may include one or more of a compressor142, a combustor144, and a turbine146including a plurality of turbine blades148coupled to turbine rotor112. Intake fan136may be coupled to turbine rotor112and configured to generate an intake air flow EIF using intake fan136(e.g., through the rotation of fan blades150) through turbine engine102. Engine air flow EAF may be some portion of or substantially all of the intake air flow EIF. In examples, intake fan136is a variable pitch fan configured to vary the pitch (e.g., blade angle) of fan blades150to, for example, very a pressure ratio between intake air flow EIF and engine air flow EAF. In examples, turbine engine102is configured to direct some portion of engine air flow EAF to engine core138as a core airflow EAC and direct another portion of engine air flow EAF to bypass engine core138as a bypass airflow EAB. Turbine engine102may be configured to direct at least some portion of engine airflow EAF (e.g., a portion of bypass airflow EAB) through jet nozzle116as exhaust flow EXF to cause an engine thrust on turbine engine102and aircraft body108. Turbine engine102may also be configured such that combustion gases produced by the combustion of fuel within engine core138are directed through jet nozzle116. Turbine rotor112may be one or more rotors configured to provide some portion of the shaft power (e.g., a torque) generated by turbine engine102. For example, turbine rotor112may include at least a first rotor152(e.g., an HP shaft) configured to provide a first portion of the shaft power to a first load (e.g., compressor142) and a second rotor154(e.g., an LP shaft) configured to provide a second portion of the shaft power to a second load (e.g., intake fan136). Turbine rotor112may be configured to vary a speed of and/or power of second rotor154relative to a speed of and/or power of first rotor152, such that, for example, a speed and/or power supplied to intake fan136may be varied substantially independently of a speed and/or power supplied to compressor142. In examples, first rotor152and second rotor154are concentric rotors configured to rotate around a common rotational axis. Within engine core138, compressor142may be configured to pressurize core airflow EAC and provide the pressurized air to combustor144. Turbine engine102may include a fuel line156configured to provide a flow of fuel to combustor144and a throttle158to control the flow of fuel. Combustor144may be configured to combust the fuel supplied via fuel line156using the pressurized air flow from compressor142. Turbine engine102may be configured to direct the resulting combustion gases to turbine146. Turbine engine102may be configured such that the directed combustion gases act on turbine blades148to cause rotation of turbine rotor112and generate shaft power (e.g., a torque on turbine rotor112). Turbine engine102may be configured to provide some portion of the shaft power to drive intake fan136, compressor142, and/or other loads, such as generators, pumps, gearboxes, boost compressors, and the like. In some examples, turbine engine102is configured to provide portions of engine air flow EAF to other systems, such as an environmental control system (ECS), a de-icing or other control surface conditioning system, a fuel tank pressurization system, other service air systems, and other systems onboard the aircraft. In this manner, turbine engine102may combust a fuel to generate engine air flow EAF and shaft power to support operations of aircraft110. Turbine engine102is configured to transfer at least some portion of the shaft power produced using turbine rotor112to transmission system118, such that transmission system118may provide at least a portion of the rotor power to shaft-driven lift fan104(e.g., in the form of mechanical power or electrical power. As discussed, transmission system118may provide the rotor power withdrawn from turbine engine102as mechanical power (e.g., using a gearbox) or as electrical power (e.g., using a generator). In some examples, A gearbox of transmission system118is configured to receive the rotor power as an input torque on an input shaft160and transfer at least some portion of the input torque to a transfer element162. Transfer element162may be, for example, an output shaft. The gearbox of transmission system118may be configured to provide at least some portion of the rotor power to shaft-driven lift fan104as an output torque via power transfer element162(e.g., an output shaft), such that shaft-driven lift fan104may provide the first thrust using the rotor power. The gearbox may include, for example, a gear train, a clutch, and/or other components configured to transfer some portion of an input torque to produce an output torque (e.g., to provide a load path from input shaft160to the output shaft). In examples, the gearbox of transmission system118is configured to vary a rotational speed of the output shaft for a given rotational speed of input shaft160. For example, the gearbox may be configured to vary the rotational speed of the output shaft through the selection of different load paths through a clutch mechanism, selection of individual gear paths providing separate overall gear ratios, and/or using other components configured to vary a rotational speed of the output shaft for a given rotational speed of input shaft160. In some examples, transmission system118includes a generator (e.g., an AC generator or DC generator) configured to receive the rotor power from turbine engine102(e.g., via input shaft160) and generate electrical power. For example, the generator may include a generator rotor configured to rotate using the rotor power to generate the electrical power. Transfer element162may be, for example, an electrical bus configured to receive the electrical power from the generator. Transmission system118may be configured to provide some portion of the electrical power to a motor of shaft-driven lift fan104, such that shaft-driven lift fan104may provide the first thrust using the rotor power. Transmission system118may include, for example, additional electrical buses, switches, electrical breakers, analog and/or digital converters, and other components configured to transfer electrical power from the generator to shaft-driven lift fan104. System100may be configured to control turbine engine102, transmission system118, and/or other components of system100to substantially control and/or determine a magnitude of the first thrust produced by shaft-driven lift fan104. System100may be configured to control turbine engine102, transmission system118, and/or other components of system100to substantially control and/or determine the shaft power withdrawn from turbine engine102to provide rotor power for use by shaft-driven lift fan104. For example, system100may be configured to control an input torque provided to a gearbox of transmission system118(e.g., using a clutch and/or another component). System100may be configured to control the electrical power generated by a generator of transmission system118(by controlling a field of the generator, a rotation of the generator rotor, or some other parameter of the generator). Shaft-driven lift fan104is configured to generate air flow AF1 (FIG.1) to provide a first vertical thrust on aircraft body108using rotor power transferred from turbine rotor112via transmission system118. As discussed, transmission system118may transfer the rotor power transferred from turbine rotor112to shaft-driven lift fan104as mechanical power (e.g., a torque) or as electrical power. Shaft-driven lift fan104may be configured to cause a rotation of a shaft-driven fan shaft164when shaft-driven lift fan104receives the rotor power transferred via transfer element162from transmission system118. Shaft-driven fan shaft164may be configured to transfer a rotary torque to a plurality of vanes166to cause shaft-driven lift fan104to generate air flow AF1. In examples, shaft-driven lift fan104includes one or more shaft-driven fan shafts including shaft-driven fan shaft164. Shaft-driven lift fan104may include one or more pluralities of vanes including plurality of vanes166, with a plurality of vanes configured to receive a rotary torque from at least one of the one or more shaft-driven fan shafts. In some examples, shaft-driven lift fan104is a multi-stage fan (e.g., a two stage fan). In some examples, shaft-driven lift fan104is a counter-rotating fan, such that shaft-driven lift fan104produces air flow AF1 by rotating a first plurality of vanes in a first rotational direction around a rotational axis and rotating a second plurality of vanes in a second rotational direction around the rotational axis, with the second rotational direction substantially opposite the first rotational direction. Shaft-driven lift fan104may be a variable pitch fan configured to vary the pitch (e.g., blade angle) of one or more of the plurality of vanes166to vary a pressure ratio across one or more stages of shaft-driven lift fan104to, for example, vary the first thrust provided by shaft-driven lift fan104, vary a pressure of engine air flow EAF within turbine engine102, or for other reasons. In some examples, shaft-driven lift fan104is configured to generate air flow AF1 through a flow path defined by a shaft-driven fan inlet168and a shaft-driven fan outlet170. Shaft-driven lift fan104may be configured to rotate vanes164to cause air flow AF1 to enter shaft-driven lift fan104through an inlet area A1 defined by a boundary of shaft-driven fan inlet168and exit shaft-driven lift fan104through an outlet area A2 defined by a boundary of shaft-driven fan outlet170. In examples, shaft-driven lift fan104is configured to vary the inlet area A1 by adjusting and/or altering a configuration of shaft-driven fan inlet168, and/or vary the outlet area A2 by adjusting and/or varying a configuration of shaft-driven fan outlet170. Shaft-driven lift fan104may be configured to vary the inlet area A1 and/or the outlet area A2 to, for example, vary the first thrust provided by shaft-driven lift fan104, vary a pressure of engine air flow EAF within turbine engine102, or for other reasons. FIG.3illustrates shaft-driven lift fan104receiving rotor power via transmission system118to cause a rotation W1 of vanes166around shaft-driven fan shaft164. The rotation W1 causes shaft-driven lift fan104to generate air flow AF1 (FIG.1) and provide the first thrust to aircraft body108.FIG.3further illustrates turbine engine102providing a gas flow GF to gas-driven lift fan106to cause a rotation W2 to generate air flow AF2 (FIG.1) and provide the second thrust to aircraft body108. In the example ofFIG.3, turbine engine102is configured to limit or substantially block exhaust flow EXF from exhausting through jet nozzle116, such that turbine engine102limits or substantially prevents production of an engine thrust on turbine engine102. However, this is not required. As discussed, system100may be configured to provide the second thrust of gas-driven lift fan106concurrently with the engine thrust of turbine engine102. Gas-driven lift fan106is configured to generate air flow AF2 (FIG.1) to provide a second vertical thrust on aircraft body108using flow energy (e.g., a kinetic energy, potential energy, and/or internal energy) transferred by gas flow GF. Turbine engine102is configured to provide gas flow GF to gas-driven lift fan106via duct120. Duct120may be configured to fluidically couple turbine engine102and gas-driven lift fan106, such that turbine engine102may provide some portion of engine air flow EAF (e.g., the gas flow) to gas-driven lift fan106. Gas-driven lift fan106is configured to receive gas flow GF from duct120and cause the rotation W2 using gas flow GF. In examples, gas-driven lift fan106is a tip turbine fan including a plurality of tip turbine blades172configured to generate a rotational torque when gas flow GF impinges on one or more of tip turbine blades172. Tip turbine blades172may be configured to impart at least some portion of the rotational torque to a plurality of gas-driven vanes174. Gas-driven vanes174may be configured to rotate (e.g., rotate about a gas-driven fan shaft176) when the rotational torque is imparted by tip turbine blades172. Gas-driven lift fan106may be configured such that the rotation of gas-driven vanes174causes gas-driven lift fan106to generate air flow AF2, causing the second thrust on aircraft body108. In examples, gas-driven lift fan106may be a variable pitch fan configured to vary a pitch (e.g., blade angle) of one or more tip turbine blades172and/or gas-driven vanes174to vary a pressure ratio across gas-driven lift fan106to, for example, vary the second thrust provided by gas-driven lift fan106, vary a pressure of engine air flow EAF within turbine engine102, or for other reasons. Gas-driven lift fan106may be configured to provide a first flow path for gas flow GF through gas-driven lift fan106and a second flow path for the generated air flow AF2 through gas-driven lift fan106. Gas-driven lift fan106may be configured to substantially separate the first flow path and the second flow path, to, for example, limit mixing of gas flow GF and air flow AF2 within gas-driven lift fan106. In examples, gas-driven lift fan includes at least one separation structure178configured to substantially separate the first flow path and the second flow path. Separation structure178may be, for example, a blade shroud, blade shoulder, or other structure configured to separate the first flow path and the second flow path. In examples, gas-driven lift fan106defines an inner surface180substantially surrounding tip turbine blades172, and gas-driven lift fan106defines the first flow path for the gas flow GF substantially between separation structure178and inner surface180. In examples, gas-driven lift fan106defines the second flow path for the air flow AF2 substantially between separation structure178and gas-driven fan shaft176. In some examples, separation structure178is configured to transmit the rotational torque generated by tip turbine blades172(e.g., generated by the impingement of gas flow GF) to the plurality of gas-driven vanes174. In examples, gas-driven lift fan106includes a gas-driven fan outlet182configured to define at a portion of the first flow path and/or the second flow path. Gas-driven lift fan106may be configured to substantially exhaust air flow AF2 and/or gas flow GF through gas driven fan outlet182to generate the second thrust on aircraft body108. In examples, gas-driven lift fan106is configured to cause air flow AF2 and/or gas flow GF to exit gas-driven lift fan106through an outlet area A3 defined by a boundary of gas-driven fan outlet182. In examples, gas-driven lift fan106is configured to vary the inlet area A3 by vary the outlet area A3 by adjusting a configuration of gas-driven fan outlet182. Gas-driven lift fan106may be configured to vary the outlet area A2 to, for example, vary the second thrust provided by gas-driven lift fan106, vary a pressure of engine air flow EAF within turbine engine102, or for other reasons. Turbine engine102may be configured to divert at least a portion of engine air flow EAF to duct120to provide gas flow GF to gas-driven lift fan106using diverter valve122. Divertor valve122may be configured to divert the portion of engine air flow EAF, such that the portion of engine air flow EAF flows into duct120rather than exhausting through jet nozzle116as exhaust air flow EXF. Divertor valve122may be configured to divert any portion (e.g., any percentage of) of engine air flow EAF to duct120to produce gas flow GF. For example, diverter valve122may be configured to divert a first percentage of engine air flow EAF to duct120in a first position, divert a second percentage of engine air flow EAF different from the first percentage in a second position, divert a third percentage of engine air flow EAF different from the first percentage and the second percentage in a third position, and so on. Hence, turbine engine102may be configured to control a magnitude of the engine thrust (produced using exhaust flow EXF) relative to a magnitude of the second thrust (produced using gas flow GF) based at least in part on a position of diverter valve122. Turbine engine102may be configured to divert the portion of engine air flow EAF at any location within turbine engine102. For example, as illustrated inFIG.2andFIG.3, turbine engine102may be configured to divert the portion of engine air flow EAF generally from exhaust section140of turbine engine102. In other examples, turbine engine102may be configured to divert the portion of engine air flow EAF generally from a portion of turbine engine102upstream of exhaust section140, such as a portion upstream or downstream from a portion of engine core138. Further, although duct120is illustrated inFIG.2andFIG.3as a single branch having a single duct inlet for discussion, duct120may include a plurality of ducts and duct inlets configured to direct some portion of engine air flow EAF to gas-driven lift fan106. Each of the plurality of duct inlets may be located anywhere within turbine engine102, such as within exhaust section140, upstream of exhaust section140, and upstream or downstream of a portion of engine core138. As used here, downstream means a direction from intake section114to exhaust section140. Upstream means a direction from exhaust section140to intake section114. FIG.4illustrates a schematic illustration of system100including turbine engine102and second turbine engine128. Turbine engine102is configured to provide rotor power to transmission system118, provide gas flow GF to gas-driven lift fan106via duct120, and provide exhaust flow EXF through jet nozzle116. Second turbine engine128is configured to provide rotor power to second transmission system130, provide a second gas flow GF2 to gas-driven lift fan106via second duct134, and provide exhaust flow EXF2 through a second jet nozzle184. System100may be configured such that only one or both of turbine engine102and second turbine engine128may provide power for the operation of shaft-driven lift fan104, second shaft-driven lift fan132, and/or gas-driven lift fan106. In examples, system100includes a transfer element186configured to transfer power between transmission system118and second transmission system130, such that turbine engine102and/or turbine engine128may provide rotor power to either or both of shaft-driven lift fan104or shaft-driven lift fan132. Transfer element186may be, for example, a shaft or other mechanical element configured to transfer mechanical power (e.g., from a first gearbox to a second gearbox) between transmission system118and second transmission system130, an electrical bus configured to transfer electrical power (e.g., from a first electrical bus to a second electrical bus) between transmission system118and second transmission system130, or some other system configured to transfer power between transmission system118and second transmission system130. For example, turbine engine102may be configured to provide a first rotor power RP1 to transmission system118. Transmission system118may be configured to transfer at least a portion of first rotor power RP1 (e.g., either as mechanical power or electrical power) as a first shaft-driven power SP1 to shaft-driven lift fan104, such that shaft-driven lift fan104may use the first shaft-driven power SP1 to generate the first thrust on aircraft body108. Turbine engine102may further provide power to gas-driven lift fan106as a first gas-driven power GP1, such that gas-driven lift fan106may use first gas-driven power GP1 to generate the second thrust on aircraft body108. Turbine engine102may further provide a first exhaust power EP1 to jet nozzle116for the production of engine thrust on aircraft body108. First gas-driven power GP1 and/or first exhaust power EP1 may be based on the flow energy (e.g., a kinetic energy, potential energy, and/or internal energy) imparted to engine air flow EAF by turbine engine102. Second turbine engine128may be configured to provide a second rotor power RP2 to second transmission system130. Second transmission system130may be configured to transfer at least a portion of second rotor power RP2 (e.g., either as mechanical power or electrical power) as a second shaft-driven power SP2 to second shaft-driven lift fan132, such that second shaft-driven lift fan132may use the second shaft-driven power SP2 to generate a third thrust on aircraft body108. Second turbine engine128may further provide power to gas-driven lift fan106as a second gas-driven power GP2, such that gas-driven lift fan106may use second gas-driven power GP2 to generate the second thrust on aircraft body108. Second turbine engine128may further provide a second exhaust power EP2 to jet nozzle184for the production of a second engine thrust on aircraft body108. Second gas-driven power GP2 and/or second exhaust power EP2 may be based on the flow energy (e.g., a kinetic energy, potential energy, and/or internal energy) imparted to a second engine air flow EAF2 by second turbine engine128. As previously discussed, althoughFIG.4illustrates only turbine engine102, transmission system118, shaft-driven lift fan104, second turbine engine128, second transmission system130, second shaft-driven lift fan132, duct120, duct134, gas-driven lift fan106, and transfer element186, system100may include any number of number of turbine engines, transmission systems, shaft-driven lift fans, ducts, gas-driven lift fans, and transfer elements. System100may be configured such that any turbine engine within system100may provide rotor power to drive one or more shaft-driven lift fans and provide gas-driven power to drive one or more gas-driven lift fans. Transfer element186may be configured to enable an exchange of power between transmission system118and second transmission system130. Thus, transmission system118may be configured to, for example, provide a first portion of first rotor power RP1 to shaft-driven lift fan104as first shaft-driven power SP1 and provide a second portion of first rotor power RP1 to second transmission system130as a first exchange power XP1 via transfer element186. Second transmission system130may be configured to use at least a portion of first exchange power XP1 to provide second shaft-driven power SP2 to second shaft-driven lift fan132. Second transmission system130may be configured such that second shaft-driven power SP2 may be comprised substantially solely of first exchange power XP1, comprised of both first exchange power XP1 and second rotor power RP2, or comprised substantially solely of second rotor power RP2. Hence, system100may be configured may be configured such that turbine engine102contributes substantially all or some portion of the rotor power used by shaft-driven lift fan104and second shaft-driven lift fan132for the production of the first thrust and the third thrust on aircraft body108. In like manner, second transmission system130may be configured to, for example, provide a first portion of second rotor power RP2 to second shaft-driven lift fan132as second shaft-driven power SP2 and provide a second portion of second rotor power RP2 to transmission system118as a second exchange power XP2 via transfer element186. Transmission system118may be configured to use at least a portion of second exchange power XP2 to provide first shaft-driven power SP1 to shaft-driven lift fan104. Transmission system118may be configured such that first shaft-driven power SP1 may be comprised substantially solely of second exchange power XP2, comprised of both second exchange power XP2 and first rotor power RP1, or comprised substantially solely of first rotor power RP1. Hence, system100may be configured such that second turbine engine128contributes substantially all or some portion of the rotor power used by shaft-driven lift fan104and second shaft-driven lift fan132for the production of the first thrust and the third thrust on aircraft body108. Although illustrated as separate transmission systems inFIG.1andFIG.4for clarity, transmission system118and second transmission system130may be substantially co-located on aircraft body108and/or housed in a common housing. Likewise, transmission system118and/or second transmission system130may be comprised of components distributed over aircraft body108, with one or more components of transmission system118and/or second transmission system130housed in individual housings. System100may be configured such that gas-driven lift fan106may receive power (e.g., GP1) substantially solely from turbine engine102, receive power (e.g., GP2) substantially solely from second turbine engine128, or receive power (e.g., GP1 and GP2) from both turbine engine102and second turbine engine128. System100may be configured to control the first gas power GP1 provided to gas-driven lift fan106(e.g., using diverter valve122) by turbine engine102. System100may be configured to control the second gas power GP2 provided to gas-driven lift fan106(e.g., using a second diverter valve188) by second turbine engine128. Hence, system100may be configured may be configured such that either turbine engine102or second turbine engine128contributes substantially all or some portion of the power used by gas-driven lift fan106for the production of the second thrust on aircraft body108. Further, system100may be configured to control (e.g., using the diverter valve122, as discussed), the first exhaust power EP1 and/or a ratio of the first exhaust power EP1 to first gas-driven power GP1 provided by turbine engine102. System100may be configured to control (e.g., using the diverter valve188in like manner to diverter valve122), the second exhaust power EP2 and/or a ratio of the second exhaust power EP2 to the second gas-driven power GP2 provided by second turbine engine128. Control circuitry124may be configured to monitor one or more of first rotor power RP1, first shaft-driven power SP1, first gas-driven power GP1, first exhaust power EP1, second rotor power RP2, second shaft-driven power SP2, first gas-driven power GP1, and/or first exhaust power EP1. In examples, control circuitry124is configured to control turbine engine102and/or second turbine engine128based on one or more of first rotor power RP1, first shaft-driven power SP1, first gas-driven power GP1, first exhaust power EP1, second rotor power RP2, second shaft-driven power SP2, first gas-driven power GP1, and/or first exhaust power EP1. In some examples, control circuitry124is configured to determine a total power requirement including a power required by at least two or more of first rotor power RP1, first shaft-driven power SP1, first gas-driven power GP1, first exhaust power EP1, second rotor power RP2, second shaft-driven power SP2, first gas-driven power GP1, and/or first exhaust power EP1. Control circuitry124may be configured to adjust an operating point of turbine engine102and/or second turbine engine128based on the total power requirement. For example, control circuitry124may be configured to determine a total power requirement for a given operating point of system100. The total power requirement may include a combined shaft-driven power including the first shaft-driven power SP1 required by shaft-driven lift fan104and the second shaft-driven power SP2 required by second shaft-driven lift fan132. The total power requirement may include a combined gas-driven power including the first gas-driven power GP1 and the second gas-driven power GP2 required by gas-driven lift fan106. The total power requirement may include a combined exhaust power including the first exhaust power EP1 and second exhaust power EP2 required from turbine engine102and second turbine engine128. Control circuitry124may be configured to adjust the operating point of turbine engine102and/or turbine engine128such that turbine engine102and second turbine engine128respectively operate to substantially satisfy the total power requirement for the given operating point of system100. In examples, control circuitry124is configured to adjust and/or control the first exchange power XP1 and/or the second exchange power XP2 exchanged between transmission system118and second transmission system130to cause turbine engine102and second turbine engine128substantially satisfy the total power requirement. In examples, control circuitry124is configured to adjust an operating point of turbine engine102to cause turbine engine102to alter the first rotor power RP1, the first gas-driven power GP1, and/or the first exhaust power EP1 provided by turbine engine102. Control circuitry124may be configured to adjust the operating point of turbine engine102to cause an increase or decrease in one or more of first rotor power RP1, the first gas-driven power GP1, and/or the first exhaust power EP1. For example, control circuitry124may be configured to alter the operating point of turbine engine102by adjusting one or more components (e.g., adjusting a position) within system100, such as throttle158, diverter valve122, jet nozzle116, shaft-driven fan outlet170, gas-driven fan outlet182, vanes166, gas-driven vanes174, tip turbine blades172, or one or more other components. Likewise, control circuitry124may be configured to alter the operating point of turbine engine102by adjusting one or more of a second throttle190configured to control a flow of fuel through second fuel line192to second turbine engine128, second diverter valve188, second jet nozzle184, a shaft-driven fan outlet of second shaft-driven lift fan132, a plurality of vanes of second shaft-driven lift fan132, or one or more other components. In some examples, control circuitry may be configured to alter the operation of turbine engine102by controlling transmission system118and/or transmission system130such that, for example, transmission system118and/or transmission system130alters the first exchange power XP1 and/or second exchange power XP2. Control circuitry124may be configured to adjust an operating point of second turbine engine128to cause second turbine engine128to alter the second rotor power RP2, the second gas-driven power GP2, and/or the second exhaust power EP2 provided by second turbine engine128. Control circuitry124may be configured to adjust the operating point of second turbine engine128to cause an increase or decrease in one or more of second rotor power RP2, the second gas-driven power GP2, and/or the second exhaust power EP2. For example, control circuitry124may be configured to alter the operating point of second turbine engine128by adjusting one or more components (e.g., adjusting a position) within system100, such as second throttle190, diverter valve188, jet nozzle184, shaft-driven fan outlet of shaft-driven lift fan132, gas-driven fan outlet182, a plurality of vanes of gas-driven lift fan106, gas-driven vanes174, tip turbine blades172, or one or more other components. Likewise, control circuitry124may be configured to alter the operating point of second turbine engine128by adjusting one or more of a throttle158, diverter valve122, jet nozzle116, shaft-driven fan outlet170, vanes166, or one or more other components. In some examples, control circuitry may be configured to alter the operation of second gas turbine engine128by controlling transmission system118and/or transmission system130such that, for example, transmission system118and/or transmission system130alters the first exchange power XP1 and/or second exchange power XP2. Control circuitry124may be configured to communicate with and/or receive communications from components with system100to, for example, monitor the operations of components within system100, monitor power flows throughout the system, determine and/or alter the operating points of turbine engine102and second turbine engine128, direct the operation and/or positioning of one or more of the components of system100, and/or for other reasons. For example, control circuitry124may be configured to communicate with turbine engine102and/or components therein (e.g., diverter valve122, jet nozzle116, intake fan136, engine core138, and/or other components of turbine engine102) using, for example, communication link194. Control circuitry124may be configured to communicate with second turbine engine128and/or components therein (e.g., diverter valve188, jet nozzle184, an intake fan of second turbine engine128, an engine core of second turbine engine128, and/or other components of second turbine engine128) using, for example, communication link195. Control circuitry124may be configured to communicate with throttle158and/or components within a fuel delivery for turbine engine102system using, for example, communication link196. Control circuitry124may be configured to communicate with throttle190and/or components within a fuel delivery for second turbine engine128using, for example, communication link197. Control circuitry124may be configured to communicate with transmission system118and/or components within transmission system118using, for example, communication link198. Control circuitry124may be configured to communicate with second transmission system130and/or components within second transmission system130using, for example, communication link199. Control circuitry124may be configured to communicate with shaft-driven lift fan104and/or components within shaft-driven lift fan104using, for example, communication link202. Control circuitry124may be configured to communicate with second shaft-driven lift fan132and/or components within second shaft-driven lift fan132using, for example, communication link203. Control circuitry124may be configured to communicate with gas-driven lift fan106and/or components within gas-driven lift fan106using, for example, communication link204. Control circuitry124may be configured to communicate with attitude control circuitry126using, for example, communication link206. Control circuitry124and/or attitude control circuitry126, as well as any other control circuitry described herein, may include any suitable arrangement of hardware, software, firmware, or any combination thereof, to perform the techniques attributed to the control circuits of this disclosure. Control circuitry124and/or attitude control circuitry126may comprise any suitable arrangement of hardware, software, firmware, or any combination thereof, to perform the techniques attributed to the control circuits of this disclosure. Control circuitry124and/or attitude control circuitry126may include any one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. When control circuitry124and/or attitude control circuitry126includes software or firmware, control circuitry124and/or attitude control circuitry126may include any necessary hardware for storing and executing the software or firmware, such as one or more processors or processing units. In general, a processing unit may include one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. The control circuits or controllers may include a memory configured to store data. The memory may include any volatile or non-volatile media, such as a random access memory (RAM), read only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, and the like. In some examples, the memory may be external to a control circuit or controller (e.g., may be external to a package in which the control circuit or controller is housed). Communication links194,195,196,197,198,202,203,204,206, as well as any other communication links described herein, may be hard-line and/or wireless communications links. In some examples, communication links194,195,196,197,198,202,203,204,206, may comprise some portion of control circuitry124, attitude control circuitry126, and/or other control circuitry described herein. Communication links194,195,196,197,198,202,203,204,206, may comprise a wired connection, a wireless Internet connection, a direct wireless connection such as wireless LAN, Bluetooth™, Wi-Fi™, and/or an infrared connection. Communication links194,195,196,197,198,202,203,204,206, may utilize any wireless or remote communication protocol. An example technique for generating a thrust on an aircraft body using a turbine engine is illustrated inFIG.5. Although the technique is described mainly with reference to system100ofFIGS.1-4, the technique may be applied to other systems in other examples. The technique includes combusting a fuel with a turbine engine102,128(502). Turbine engine102,128may mechanically rotate a turbine rotor112to generate shaft power and generate an engine air flow EAF, EAF2 through turbine engine102,128using the fuel combustion. Turbine engine102,128may provide an engine thrust to an aircraft body108using an exhaust flow EXF exhausted through a jet nozzle116,184. The exhaust flow EXF may be a portion of the engine air flow EAF, EAF2. Turbine engine102,128may be mechanically supported by an aircraft body108of an aircraft110. In examples, turbine engine102,128combusts the fuel within an engine core138. Turbine engine102,128may compress a portion of engine air flow EAF, EAF2 (e.g., a core airflow EAC) using a compressor142powered by the shaft power. Compressor142may provide compressed to a combustor144. Combustor144may receive the fuel and combust the fuel using the compressed air to generate combustion gases. Turbine engine102,128may generate the shaft power by causing a rotation of turbine rotor112when the combustion gases impinge on a plurality of turbine blades148. Turbine engine102,128may provide a portion of the shaft power to compressor142and an intake fan136configured to provide the engine air flow EAF, EAF2. The technique includes generating a first thrust and/or third thrust on aircraft body108using rotor power transferred from turbine engine102,128(504). The rotor power may be a portion of the shaft power generated by turbine engine102,128. A transmission system118,130may receive the rotor power from turbine engine102,128and transfer at least some portion of the rotor power to a shaft-driven lift fan104,132. In examples, shaft-driven lift fan104,132mechanically supported by aircraft body108uses the rotor power to produce an air flow AF1, AF3. Shaft-driven lift fan104,132may direct the air flow AF1, AF3 in a direction away from aircraft body108to produce the first thrust and/or third thrust on shaft-driven lift fan104,132. Shaft-driven lift fan104,132may transfer the first thrust and/or third thrust to aircraft body108. In examples, shaft-driven lift fan104,132rotates a plurality of vanes166around a fan shaft164using the rotor power. The rotation of vanes166may generate the air flow AF1, AF3. In examples, transmission system118,130is configured to transfer the portion of rotor power to shaft-driven lift fan104,132as mechanical power. Transmission system118,130may receive the rotor power as an input torque from turbine engine102,128and transfer the portion of the rotor power to shaft-driven lift fan104,132as an output torque. In examples, transmission system118,130is configured to transfer the portion of rotor power to shaft-driven lift fan104,132as electrical power. Transmission system118,130may receive the rotor power as an input torque from turbine engine102,128and generate the electrical power using the input torque. Transmission system118,130may transfer some portion of the generated electrical power to shaft-driven lift fan104,132using one or more electrical buses and/or other electrical distribution components. The technique includes generating a second thrust on aircraft body108using a gas flow GF1, GF2 (506). Gas flow GF1, GF2 may be a portion of engine air flow EAF1, EAF2. Turbine engine102,128may divert some portion of engine air flow EAF1, EAF2 to cause gas flow GF1, GF2. Turbine engine102,128divert the portion of engine air flow EAF1, EAF2 such that gas flow GF1, GF2 flow through duct120,134and substantially bypasses jet nozzle116,184. In examples, turbine engine102,128causes gas flow GF1, GF2 using a diverter valve122,188within turbine engine102,128. Duct120,134may provide GF1, GF2 to a gas-driven lift fan106mechanically supported by aircraft body108. Gas-driven lift fan106may uses gas flow GF1, GF2 an air flow AF2. Gas-driven lift fan106may direct the air flow AF2 in a direction away from aircraft body108to produce the second thrust on gas-driven lift fan106. Gas-driven lift fan106may transfer the second thrust to aircraft body108. In examples, gas-driven lift fan106rotates a plurality of tip turbine blades172using gas flow GF1, GF2. The rotation of tip turbine blades may cause a rotation of a plurality of gas-driven vanes174to generate the air flow AF2. A transfer element186may exchange of power between transmission system118and second transmission system130. In examples, turbine engine102,128provides a first portion of a rotor power RP1, RP2 to a transmission system (e.g., one of transmission system118or second transmission system130) as shaft-driven power SP1, SP2 and provides a second portion of rotor power RP1, RP2 to another transmission system (e.g., the other of transmission system118or second transmission system130) as a first exchange power XP1 via a transfer element186. Turbine engine102,128may contribute substantially all or some portion of the rotor power used by shaft-driven lift fan104and second shaft-driven lift fan132for the production of the first thrust and the third thrust on aircraft body108. Gas-driven lift fan106may receive substantially all or some portion of a power GP1, GP2 from turbine engine102,128to generate the second thrust. Control circuitry124may monitor one or more of rotor power RP1, RP2, shaft-driven power SP1, SP2, gas-driven power GP1, GP2, exhaust power EP1, EP2, and exchange power XP1, XP2. Control circuitry124may control turbine engine102,128based on one or more of rotor power RP1, RP2, shaft-driven power SP1, SP2, gas-driven power GP1, GP2, exhaust power EP1, EP2, and exchange power XP1, XP2. In some examples, control circuitry124may determine a total power requirement including a power required by at least two or more of rotor power RP1, RP2, shaft-driven power SP1, SP2, gas-driven power GP1, GP2, exhaust power EP1, EP2, and exchange power XP1, XP2. Control circuitry124adjust an operating point of turbine engine102,128based on the total power requirement. The present disclosure includes the following examples. Example 1: A system comprising: a turbine engine configured to combust a fuel to mechanically rotate a rotor to generate shaft power and generate an engine air flow through the turbine engine, wherein the turbine engine is configured to provide an engine thrust to an aircraft body using an exhaust flow, and wherein the exhaust flow is a portion of the engine air flow; a shaft-driven lift fan configured to rotate to provide a first thrust to the aircraft body using rotor power transferred from the rotor, wherein the rotor power is at least a portion of the shaft power; and a gas-driven lift fan configured to rotate to provide a second thrust to the aircraft body using a gas flow, wherein the gas flow is another portion of the engine air flow. Example 2: The system of example 1, wherein the gas-driven lift fan includes tip turbine blades configured to generate a rotary motion when the gas flow impinges on one or more tips of the tip turbine blades, and wherein the gas-driven lift fan is configured to generate the second thrust using the rotary motion. Example 3: The system of example 2 or example 3, wherein the turbine engine is configured to generate the engine thrust by exhausting the exhaust flow through at nozzle of the turbine engine, and further comprising a duct configured to cause the gas flow to selectively bypass the nozzle to supply the gas flow to the gas-driven lift fan. Example 4: The system of example 3, further comprising a second turbine engine configured to generate a second engine air flow through the second turbine engine, wherein the second turbine engine is configured to provide a second engine thrust to the aircraft body by exhausting a second exhaust flow through a second nozzle, wherein the second exhaust flow is a portion of the second engine air flow, wherein the duct is configured to cause a second gas flow to selectively bypass the second nozzle to supply the second gas flow to the gas-driven lift fan, wherein the second gas flow is another portion of the second engine air flow, and wherein the gas-driven lift fan is configured to rotate to provide the second thrust using the second gas flow. Example 5: The system of any of examples 1-4, wherein the shaft-driven lift fan includes a fan shaft and a plurality of vanes, wherein the fan shaft is configured to generate a rotary torque using the rotor power, and wherein the plurality of vanes are configured to generate the first thrust when the fan shaft transmits the rotary torque to the plurality of vanes. Example 6: The system of example 5, further comprising a transmission system operably coupled to the rotor and the fan shaft, wherein the transmission system is configured to control the rotor power transferred from the rotor to the fan shaft. Example 7: The system of example 6, wherein the transmission system includes a gearbox mechanically coupled to the rotor and the fan shaft, wherein the gearbox is configured to provide the rotor power to the fan shaft to cause the fan shaft to generate the rotary torque. Example 8: The system of example 6 or example 7, wherein the transmission system includes a generator configured to generate electrical power using the rotor power, and wherein the transmission system is configured to provide the electrical power to a motor operably coupled to the fan shaft to cause the fan shaft to generate the rotary torque. Example 9: The system of any of examples 1-8, further comprising a second turbine engine configured to mechanically rotate a second rotor to generate a second rotor power, wherein the shaft-driven lift fan is configured to rotate to provide the first thrust to the aircraft body using the second rotor power transferred from the second rotor. Example 10: The system of any of examples 1-9, further comprising a transmission system configured to vary the rotor power provided to the shaft-driven lift fan to vary the first thrust as the turbine engine mechanically rotates the rotor. Example 11: The system of any of examples 1-10, further comprising control circuitry configured to: determine a first power requirement required for the shaft-driven lift fan to provide the first thrust; determine a second power requirement required for the gas-driven lift fan to provide the second thrust as the shaft-driven lift fan provides the first thrust; and control an operating point of the turbine engine based on at least the first power requirement and the second power requirement. Example 12: The system of example 11, wherein the control circuitry is configured to: determine a third power requirement required for the turbine engine to provide the engine thrust; and control the operating point of the turbine engine based on at least the first power requirement, the second power requirement, and the third power requirement. Example 13: The system of any of examples 1-12, further comprising: an attitude control system configured to monitor an attitude of the aircraft body; and control circuitry configured to cause the shaft-driven lift fan to provide an amount of the first thrust and cause the gas-driven lift fan to provide an amount of the second thrust based at least in part on a signal indicative of the attitude from the attitude control system. Example 14: The system of any of examples 1-13, wherein at least one of the shaft-driven lift fan is configured to vary a direction of the first thrust relative to the aircraft body or the gas-driven lift fan is configured to vary a direction of the second thrust relative to the aircraft body. Example 15: The system of any of examples 1-14, wherein the shaft-driven lift fan is configured to provide the first thrust in a first direction substantially perpendicular to a longitudinal axis of the aircraft body, wherein the gas-driven lift fan is configured to provide the second thrust in a second direction substantially perpendicular to the longitudinal axis of the aircraft body, and wherein the turbine engine is configured to provide the engine thrust in a direction substantially parallel to the longitudinal axis of the aircraft body. Example 16: A system comprising: a first turbine engine configured to combust a first fuel to mechanically rotate a first rotor to generate a first shaft power and generate a first engine air flow through the first turbine engine, wherein the first turbine engine is configured to provide a first engine thrust to an aircraft body using a first exhaust flow, and wherein the first exhaust flow is a portion of the first engine air flow; a second turbine engine configured to combust a second fuel to mechanically rotate a second rotor to generate a second shaft power and generate a second engine air flow through the second turbine engine, wherein the second turbine engine is configured to provide a second engine thrust to the aircraft body using a second exhaust flow, and wherein the second exhaust flow is a portion of the second engine air flow; a shaft-driven lift fan configured to rotate to provide a first thrust to the aircraft body using at least one of a first rotor power transferred from the first rotor or a second rotor power transferred from the second rotor, wherein the first rotor power is a portion of the first shaft power and the second rotor power is a portion of the second shaft power; and a gas-driven lift fan configured to rotate to provide a second thrust to the aircraft body using at least one of a first gas flow or a second gas flow, wherein the first gas flow is another portion of the first engine air flow and the second gas flow is another portion of the second engine air flow. Example 17: The system of example 16, wherein the first turbine is configured to generate the first engine thrust by exhausting the first exhaust flow through a first nozzle of the first turbine engine, and wherein the second turbine is configured to generate the second engine thrust by exhausting the second exhaust flow through a second nozzle of the second turbine engine, and further comprising: a duct configured to cause the first gas flow to selectively bypass the first nozzle and cause the second gas flow to selectively bypass the second nozzle to supply at least one of the first gas flow or the second gas flow to the gas-driven lift fan. Example 18: The system of example 16 or example 17, wherein: the shaft-driven fan includes a fan shaft and a plurality of blades, wherein the fan shaft is configured to generate a rotary torque using at least one of the first rotor power or the second rotor power, and wherein the fan blades are configured to generate the first thrust when the fan shaft transmits the rotary torque to the plurality of fan blades; and the gas-driven lift fan includes tip turbine blades configured to generate a rotary motion when at least one of the first gas flow or the second gas flow impinges on one or more tips of the tip turbine blades, wherein the gas-driven lift fan is configured to generate the second thrust using the rotary motion. Example 19: A method comprising: combusting a fuel with a turbine engine to mechanically rotate a rotor to generate shaft power and generate an engine air flow through the turbine engine, wherein the turbine engine is configured to provide an engine thrust to an aircraft body using an exhaust flow, and wherein the exhaust flow is a portion of the engine air flow; generating a first thrust on the aircraft body using a shaft-driven lift fan configured to rotate using rotor power transferred from the rotor, wherein the rotor power is at least a portion of the shaft power; and generating a second thrust on the aircraft body using a gas-driven lift fan configured to rotate using a gas flow, wherein the gas flow is another portion of the engine air flow. Example 20: The method of example 19, further comprising: determining, using control circuitry, a first power requirement required for the shaft-driven lift fan to provide the first thrust; determining, using the control circuitry, a second power requirement required for the gas-driven lift fan to provide the second thrust as the mechanically driven fan provides the first thrust; and controlling, using the control circuitry, an operating point of the turbine engine based on at least the first power requirement and the second power requirement. Various examples have been described. These and other examples are within the scope of the following claims. | 82,092 |
11859543 | DETAILED DESCRIPTION FIG.1illustrates a gas turbine engine10of a type preferably provided for use in subsonic flight, generally comprising in serial flow communication along an engine center axis11a fan12through which ambient air is propelled, a compressor section14for pressurizing the air, a combustor16in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section18for extracting energy from the combustion gases. The compressor section14may include a plurality of stators13and rotors15(only one stator13and rotor15being shown inFIG.1), and it may include a centrifugal compressor19. The centrifugal compressor19of the compressor section14includes an impeller17and a plurality of diffuser pipes20, which are located downstream of the impeller17and circumferentially disposed about a periphery of a radial outlet17A of the impeller17. The diffuser pipes20convert high kinetic energy at the impeller17exit to static pressure by slowing down fluid flow exiting the impeller. The diffuser pipes20may also redirect the air flow from a radial orientation to an axial orientation (i.e. aligned with the engine axis11). In most cases, the Mach number of the flow entering the diffuser pipe20may be at or near sonic, while the Mach number exiting the diffuser pipe20may be less than 0.25 to enable stable air/fuel mixing, and light/re-light in the combustor16. FIG.2shows the impeller17and the plurality of diffuser pipes20, also referred to as “fishtail diffuser pipes”, of the centrifugal compressor19. Each of the diffuser pipes20includes a diverging (in a downstream direction) tubular body22, formed, in one embodiment, of sheet metal. The enclosed tubular body22defines a flow passage29(seeFIG.3) extending through the diffuser pipe20through which the compressed fluid flow is conveyed. The tubular body22includes a first portion24extending generally tangentially from the periphery and radial outlet17A of the impeller17. An open end is provided at an upstream end of the tubular body22and forms an inlet23(seeFIG.3) of the diffuser pipe20. The first portion24is inclined at an angle θ1relative to a radial axis R extending from the engine axis11. The angle θ1may be at least partially tangential, or even substantially tangentially, and may further correspond to a direction of fluid flow at the exit of the blades of the impeller17, such as to facilitate transition of the flow from the impeller17to the diffuser pipes20. The first portion24of the tubular body22can alternatively extend more substantially along the radial axis R. The tubular body22of the diffuser pipes20also includes a second portion26, which is disposed generally axially and is connected to the first portion24by an out-of-plane curved or bend portion28. An open end at the downstream end of the second portion26forms a pipe outlet25(seeFIG.3) of the diffuser pipe20. Preferably, but not necessarily, the first portion24and the second portion26of the diffuser pipes20are integrally formed together and extend substantially uninterrupted between each other, via the curved, bend portion28. The large radial velocity component of the flow exiting the impeller17, and therefore entering the first portion24of each of the diffuser pipes20, may be removed by shaping the diffuser pipe20with the bend portion28, such that the flow is redirected axially through the second portion26before exiting via the pipe outlet25to the combustor16. It will thus be appreciated that the flow exiting the impeller17enters the inlet23and the upstream first portion24and flows along a generally radial first direction. At the outlet of the first portion24, the flow enters the bend portion28which functions to turn the flow from a substantially radial direction to a substantially axial direction. The bend portion28may form a 90 degree bend. At the outlet of the bend portion28, the flow enters the downstream second portion26and flows along a substantially axial second direction different from the generally radial first direction. By “generally radial”, it is understood that the flow may have axial, radial, and/or circumferential velocity components, but that the axial and circumferential velocity components are much smaller in magnitude than the radial velocity component. Similarly, by “generally axial”, it is understood that the flow may have axial, radial, and/or circumferential velocity components, but that the radial and circumferential velocity components are much smaller in magnitude than the axial velocity component. Referring now toFIG.3, the tubular body22of each diffuser pipe20has a radially inner wall22A and a radially outer wall22B. The tubular body22also has a first side wall22C spaced circumferentially apart across the flow passage29from a second side wall22D. The radially inner and outer walls22A,22B and the first and second side walls22C,22D meet and are connected to form the enclosed flow passage29extending through the tubular body22. The radially inner and outer walls22A,22B and the first and second side walls22C,22D meet and are connected to form a peripheral edge of the tubular body22which circumscribes the pipe outlet25. The radially inner wall22A corresponds to the wall of the tubular body22that has the smallest turning radius at the bend portion28, and the radially outer wall22B corresponds to the wall of the tubular body22that has the largest turning radius at the bend portion28. The tubular body22diverges in the direction of fluid flow F therethrough, in that the internal flow passage29defined within the tubular body22increases in cross-sectional area between the inlet23and the pipe outlet25of the tubular body22. The increase in cross-sectional area of the flow passage29through each diffuser pipe20is gradual over some of diffuser pipe20and more abrupt in parts of the second portion26, as described in greater detail below. The direction of fluid flow F is along a pipe center axis21of the tubular body22. The pipe center axis21extends through each of the first, second, and bend portions24,26,28and has the same orientation as these portions. The pipe center axis21is thus curved. In the depicted embodiment, the pipe center axis21is equidistantly spaced from the radially inner and outer walls22A,22B of the tubular body22, and from the first and second side walls22C,22D, through the tubular body22. Still referring toFIG.3, the tubular body22has a length L defined from the inlet23to the pipe outlet25. The length L of the tubular body22may be measured as desired. For example, inFIG.3, the length L is the length of the pipe center axis21from the inlet23to the pipe outlet25. In an alternate embodiment, the length L is measured along one of the walls22A,22B,22C,22D of the tubular body22, from the inlet23to the pipe outlet25. Reference is made herein to positions on the tubular body22along its length L. For example, a position on the tubular body22that is along a last 10% of the length L is anywhere in the segment of the tubular body22that is upstream of the pipe outlet25a distance equal to 10% of the length L. This same segment is also downstream of the inlet23a distance equal to 90% of the length L. Similarly, a position on the tubular body22that is along a first 90% of the length L is anywhere in the segment of the tubular body22that is downstream of the inlet23a distance equal to 90% of the length L. This same segment is also upstream of the pipe outlet25a distance equal to 10% of the length L. The tubular body22is composed of many cross-sectional profiles27which are arranged or stacked one against another along the length L of the tubular body22. Each cross-sectional profile27is a planar contour that lies in its own plane that is transverse or normal to the pipe center axis21.FIG.3shows multiple cross-sectional profiles27in every portion24,26,28of the tubular body22, and it will be appreciated that many more cross-sectional profiles27may be defined at other locations along the pipe center axis21. In the depicted embodiment, the orientation of the cross-sectional profiles27in the frame of reference of the diffuser pipe20may vary over the length L of the tubular body22, depending on where the cross-sectional profiles27are located along the pipe center axis21. Each cross-sectional profile27defines the shape, contour, or outline of the tubular body22at a specific location along the pipe center axis21. Referring toFIG.3, and as described in greater detail below, the cross-sectional profiles27vary over the length L of the tubular body22. The cross-sectional profiles27are different over the length L of the tubular body22. Each cross-sectional profile27may be unique, and thus different from the other cross-sectional profiles27. An area of the cross-sectional profiles27varies along the length L of the tubular body22. The area of a given cross-sectional profile27is defined between the inner, outer, first side, and second side walls22A,22B,22C,22D in the cross-sectional profile27. The area of the cross-sectional profiles27increases over the length L of the tubular body22in the direction of the pipe outlet25. This is consistent with the diverging flow passage29defined by the tubular body22. FIG.4plots a normalized value for the area of the cross-sectional profiles27of the tubular body22at different points along the length L of the tubular body22, where the length L is provided as a normalized meanline length. The “meanline” describes the locus of points from the inlet23to the pipe outlet25where each point is defined as the center of each section. A final value for the cross-sectional area of the tubular body22is defined at the pipe outlet25, and is shown inFIG.4as corresponding to 100% of the normalized value for the area of the cross-sectional profile27at the pipe outlet25. The final value is the highest value for the cross-sectional area of the tubular body22.FIG.4shows the area curves for the tubular bodies22of diffuser pipes20with different area distributions along their lengths L. Referring toFIGS.3and4, the tubular body22flares outwardly adjacent to the pipe outlet25. More particularly, the area of the cross-sectional profiles27in the last 10% of the length L of the tubular body22increases by 20% or more. InFIG.4, this is shown as the area of the cross-sectional profiles27going from about 50% of the final value to 100% of the final value, over the last 10% of the length L of the tubular body22. The cross-sectional area of the diffuser pipe20thus increases rapidly in the last section of the diffuser pipe20, right before the pipe outlet25, thereby forming a diffuser pipe20which flares outwardly, like a trumpet, at the end portion thereof. The cross-sectional area of the diffuser pipe20does not increase after the pipe outlet25, and achieves the final value at the pipe outlet25. The diffuser pipe20therefore ends or terminates at the pipe outlet25. Referring toFIG.4, the area curve30A for the tubular body22inFIG.3shows that the area of the cross-sectional profile27at the pipe outlet25is more than 20% greater than the area of the cross-sectional profile27at a point or plane where the last 10% of the length L of the tubular body22begins. Stated differently, an area of the cross-sectional profile at the pipe outlet is at least 20% greater than an area of the cross-sectional profile at a point upstream from the pipe outlet a distance corresponding to 10% of the length of the tubular body. The area curve30A for the tubular body22inFIG.3shows that the area of the cross-sectional profile27at the pipe outlet25is more than 25% greater than the area of the cross-sectional profile27at the beginning of the last 10% of the length L of the tubular body22. InFIG.4, this is shown as the area of the cross-sectional profiles27for the area curve30A going from about 50% of the final value to 100% of the final value, over the last 10% of the length L of the tubular body22. Thus, for the area curve30A, the cross-sectional profiles27increase in area by 50% or more over the last 10% of the length L. For the area curve30A, the area of the cross-sectional profile27at the pipe outlet25is more than 50% greater than the area of the cross-sectional profile27immediately upstream of the last 10% of the length L. Thus the area of the cross-sectional profiles27in the last 10% of the length L of the area curve30A increases by more than 25%, or by at least 25%. For the area curve30A, the cross-sectional profiles27increase in area by at least 40% over the last 20% of the length L of the tubular body22. InFIG.4, this is shown as the area of the cross-sectional profiles27for the area curve30A going from about 40% of the final value to 100% of the final value, over the last 20% of the length L of the tubular body22. More particularly, the area of the cross-sectional profile27at the pipe outlet25in the area curve30A is about 60% greater than the area of the cross-sectional profile27at the last 20% of the length L. The diffuser pipe20having the area curve30A thereby undergoes an area change of at least 60% in the last 20% of the length L of the diffuser pipe20. Indeed, and as shown inFIG.4, the cross-sectional profiles27of the area curve30A increase in area by more than 50% over the last 20% of the length L. For the area curve30A, the cross-sectional profiles27increase in area by at least 50% over the last 30% of the length L of the tubular body22. For the area curve30A, the cross-sectional profiles27increase in area by at least 50% over the last 25% of the length L of the tubular body22. InFIG.4, this is shown as the area of the cross-sectional profiles27for the area curve30A going from about 33% of the final value to 100% of the final value, over the last 30% of the length L of the tubular body22. The diffuser pipe20having the area curve30A thereby undergoes an area change of at least 50% in the last 25% of the length L of the diffuser pipe20. The area curve30A shows that the diffuser pipe20may undergo increases in the area of its cross-sectional profiles27of 50% or more in the last 10% of the length L of the diffuser pipe20, in the last 20% of the length L of the diffuser pipe20, and/or in the last 25% of the length L of the diffuser pipe20. Referring toFIG.4, another possible area curve30B for the tubular body22inFIG.3shows that the area of the cross-sectional profile27at the pipe outlet25is 20% greater than the area of the cross-sectional profile27at the last 10% of the length L of the tubular body22. Thus the area of the cross-sectional profiles27in the last 10% of the length L of the area curve30B increases by 20%. InFIG.4, this is shown as the area of the cross-sectional profiles27for the area curve30B going from about 80% of the final value to 100% of the final value, over the last 10% of the length L of the tubular body22. Another possible area curve30C for the tubular body22inFIG.3shows that the area of the cross-sectional profile27at the pipe outlet25is 33% greater than the area of the cross-sectional profile27at the last 20% of the length L of the tubular body22. InFIG.4, this is shown as the area of the cross-sectional profiles27for the area curve30C going from about 66% of the final value to 100% of the final value, over the last 20% of the length L of the tubular body22. The area curve30D shows that the area of the cross-sectional profile27at the pipe outlet25is 33% greater than the area of the cross-sectional profile27at the last 30% of the length L of the tubular body22. InFIG.4, this is shown as the area of the cross-sectional profiles27for the area curve30D going from about 66% of the final value to 100% of the final value, over the last 30% of the length L of the tubular body22. The increase in cross-sectional area of the diffuser pipe20over a short distance of the diffuser pipe20may allow for rapid diffusion at the exit of the diffuser pipe20. This may lead to increased static pressure prior to providing the fluid flow F downstream into a plenum and ultimately into the combustion chamber of the combustor16. Since diffusion occurs rapidly and over a short distance at the exit of the diffuser pipe20, there may be lower pressure loss when compared to a conventional diffuser pipe where diffusion occurs over a more gradual increase in cross-sectional area. Thus the distribution of the cross-sectional area toward the exit of the diffuser pipe20may result in higher static pressure recovery and lower loss. The area curve30E for such a conventional diffuser pipe, where diffusion occurs over a more gradual increase in cross-sectional area, is shown inFIG.4. As can be seen, the cross-sectional area in the area curve30E increases in a substantially linear manner over the length of the conventional diffuser pipe. Still referring toFIG.4, an upstream area of the diffuser pipe20has a more gradual increase in the area of the cross-sectional profiles27. Referring to the area curves30A,30B,30C, the cross-sectional profiles27increase linearly in area over an upstream segment of the tubular body22starting at 0% of the length L of the tubular body (i.e. at the inlet23) and terminating at approximately 80% of the length L. The slope of the area curves30A,30B,30C is substantially constant over the upstream segment. Thus, the tubular body22represented by the area curves30A,30B,30C increase gradually in cross-sectional area over the upstream segment. Stated differently, the increase in area of the diffuser pipe20represented by the area curves30A,30B,30C is much greater near the exit of the diffuser pipe20than further upstream within the diffuser pipe20. Thus, diffusion occurs through a majority of the pipe length, and more diffusion occurs near the exit of the diffuser pipe20. The upstream segment of the diffuser pipe20may also have other shapes and profiles. As seen inFIG.4, all of the area curves30A,30B,30C,30D, including the area curve30E for the conventional diffuser pipe, have the same value for the area of their respective cross-sectional profiles27at the pipe outlet25. In an embodiment, the radius of the diffuser pipe20, its length L along the pipe center axis21, and its overall area ratio are the same as that of the conventional diffuser pipe. The primary difference is that the diffuser pipe20performs less diffusion through a majority of the pipe length and more diffuser near the exit, compared to the conventional diffuser pipe. FIG.5shows possible lines of the fluid flow F through the diffuser pipe20. As can be seen, the fluid flow F may remain clean and oriented parallel to the pipe center axis21through most of the diffuser pipe20. The fluid flow F may be cleaner throughout upstream sections of the diffuser pipe20because of less diffusion, and there may be a reduction in separated fluid flow F near the exit. The exit flare of the diffuser pipe20may help to lower the average exit Mach number, may help to increases Cp (static pressure recovery), and/or may help to lower the omega (ω) loss. FIG.6shows equivalent cone angle (ECA) plotted along the length L of the tubular body22, where the length L is provided as a normalized meanline length. A larger ECA value is generally an indication of more diffusion and potentially more pressure loss. A lower ECA value is preferable when the flow path of the diffuser pipe20is turning (i.e. in the bend portion). A higher ECA value after the turning can indicate that flow is diffusing more efficiently. It can be seen that the diffuser pipe20has a lower ECA through most of the length L of the diffuser pipe20when compared to a conventional diffuser pipe, which contributes to lower diffusion and loss in the bend portion28of the diffuser pipe20. Static pressure recovery (Cp), losses (ω) and the ECA are determined according to the following formulae: Cp=Ps,outlet-Ps,inletPr,inlet-Ps,inletω=Pt,inlet-Pt,outletPt,inlet-Ps,inletECA=2×tan-1(A2πA1πL) Where Ps is the static pressure, Pt is the total pressure (Ps+pressure from kinetic energy), A1 is the cross-sectional area of diffuser pipe20at the inlet23, A2 is the cross-sectional area of diffuser pipe20at the pipe outlet25, and L is the meanline length of the diffuser pipe20. Referring toFIGS.3and4, there is also disclosed a method of increasing static pressure of fluid at the combustor16. The method includes conveying the fluid through the diffuser pipe20to rapidly diffuse the fluid through a last 10% of the length L, over which a cross-sectional area of the diffuser pipe20increases by at least 20%. The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims. | 20,977 |
11859544 | DETAILED DESCRIPTION The detailed description set forth below, in connection with the accompanying drawings, is intended as a description of various embodiments, and is not intended to represent the only embodiments in which the disclosure may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the embodiments. However, it will be apparent to those skilled in the art that embodiments of the invention can be practiced without these specific details. In some instances, well-known structures and components are shown in simplified form for brevity of description. For clarity and ease of explanation, some surfaces and details may be omitted in the present description and figures. In addition, references herein to “upstream” and “downstream” or “forward” and “aft” are relative to the flow direction of the primary gas (e.g., air) used in the combustion process, unless specified otherwise. It should be understood that “upstream,” “forward,” and “leading” refer to a position that is closer to the source of the primary gas or a direction towards the source of the primary gas, and “downstream,” “aft,” and “trailing” refer to a position that is farther from the source of the primary gas or a direction that is away from the source of the primary gas. Thus, a trailing edge or end of a component (e.g., a turbine blade) is downstream from a leading edge or end of the same component. Also, it should be understood that, as used herein, the terms “side,” “top,” “bottom,” “front,” “rear,” “above,” “below,” and the like are used for convenience of understanding to convey the relative positions of various components with respect to each other, and do not imply any specific orientation of those components in absolute terms (e.g., with respect to the external environment or the ground). It should also be understood that the various components illustrated herein are not necessarily drawn to scale. In other words, the features disclosed in various embodiments may be implemented using different relative dimensions within and between components than those illustrated in the drawings. FIG.1illustrates a schematic diagram of a gas turbine engine100, according to an embodiment. Gas turbine engine100comprises a shaft102with a central longitudinal axis L. A number of other components of gas turbine engine100are concentric with longitudinal axis L and may be annular to longitudinal axis L. A radial axis may refer to any axis or direction that radiates outward from longitudinal axis L at a substantially orthogonal angle to longitudinal axis L, such as radial axis R inFIG.1. Thus, the term “radially outward” should be understood to mean farther from or away from longitudinal axis L, whereas the term “radially inward” should be understood to mean closer or towards longitudinal axis L. As used herein, the term “radial” will refer to any axis or direction that is substantially perpendicular to longitudinal axis L, and the term “axial” will refer to any axis or direction that is substantially parallel to longitudinal axis L. In an embodiment, gas turbine engine100comprises, from an upstream end to a downstream end, an inlet110, a compressor120, a combustor130, a turbine140, and an exhaust outlet150. In addition, the downstream end of gas turbine engine100may comprise a power output coupling104. One or more, including potentially all, of these components of gas turbine engine100may be made from stainless steel and/or durable, high-temperature materials known as “superalloys.” A superalloy is an alloy that exhibits excellent mechanical strength and creep resistance at high temperatures, good surface stability, and corrosion and oxidation resistance. Examples of superalloys include, without limitation, Hastelloy, Inconel, Waspaloy, Rene alloys, Haynes alloys, Incoloy, MP98T, TMS alloys, and CMSX single crystal alloys. Inlet110may funnel a working fluid F (e.g., the primary gas, such as air) into an annular flow path112around longitudinal axis L. Working fluid F flows through inlet110into compressor120. While working fluid F is illustrated as flowing into inlet110from a particular direction and at an angle that is substantially orthogonal to longitudinal axis L, it should be understood that inlet110may be configured to receive working fluid F from any direction and at any angle that is appropriate for the particular application of gas turbine engine100. While working fluid F will primarily be described herein as air, it should be understood that working fluid F could comprise other fluids, including other gases. Compressor120may comprise a series of compressor rotor assemblies122and stator assemblies124. Each compressor rotor assembly122may comprise a rotor disk that is circumferentially populated with a plurality of rotor blades. The rotor blades in a rotor disk are separated, along the axial axis, from the rotor blades in an adjacent disk by a stator assembly124. Compressor120compresses working fluid F through a series of stages corresponding to each compressor rotor assembly122. The compressed working fluid F then flows from compressor120into combustor130. Combustor130may comprise a combustor case132that houses one or more, and generally a plurality of, fuel injectors134. In an embodiment with a plurality of fuel injectors134, fuel injectors134may be arranged circumferentially around longitudinal axis L within combustor case132at equidistant intervals. Combustor case132diffuses working fluid F, and fuel injector(s)134inject fuel into working fluid F. This injected fuel is ignited to produce a combustion reaction in one or more combustion chambers136. The product of the combustion reaction drives turbine140. Turbine140may comprise one or more turbine rotor assemblies142and stator assemblies144(e.g., nozzles). Each turbine rotor assembly142may correspond to one of a plurality or series of stages. Turbine140extracts energy from the combusting fuel-gas mixture as it passes through each stage. The energy extracted by turbine140may be transferred via power output coupling104(e.g., to an external system), as well as to compressor120via shaft102. The exhaust E from turbine140may flow into exhaust outlet150. Exhaust outlet150may comprise an exhaust diffuser152, which diffuses exhaust E, and an exhaust collector154which collects, redirects, and outputs exhaust E. It should be understood that exhaust E, output by exhaust collector154, may be further processed, for example, to reduce harmful emissions, recover heat, and/or the like. In addition, while exhaust E is illustrated as flowing out of exhaust outlet150in a specific direction and at an angle that is substantially orthogonal to longitudinal axis L, it should be understood that exhaust outlet150may be configured to output exhaust E towards any direction and at any angle that is appropriate for the particular application of gas turbine engine100. FIG.2illustrates a block diagram of an example closed system200comprising a gas turbine engine100, according to an embodiment. While particular components are illustrated, one or more of the illustrated components may be omitted from closed system200and/or additional components may be incorporated into closed system200. In addition, while a particular arrangement of components is illustrated, the components may be arranged differently within closed system200. As illustrated, closed system200may comprise an air inlet210, a mixer box300, a generator220, a gas turbine engine100, valves230and235, a cooling system240, an oxygen mixer250, and a carbon-capture system260. During operation, air inlet210may take in and filter an external gas205, such as fresh air, and introduce the filtered external gas205into closed system200as inlet gas215. Inlet gas215and recirculated exhaust gas255may flow into mixer box300, where they are mixed together to produce mixed gas305. Mixed gas305flows, as working fluid F, into gas turbine engine100(e.g., into inlet110), which may power generator220(e.g., via output coupling104). As described above, gas turbine engine outputs exhaust E (e.g., via exhaust outlet150), as exhaust gas225. Exhaust gas225may flow through an exhaust recirculation system, comprising valve230, cooling system240, and/or oxygen mixer250. During startup or during a non-recirculation cycle, valve230may be closed while valve235is opened, such that exhaust gas225is released to the atmosphere. To begin recirculating exhaust gas225, valve230transitions to fully open, while valve235transitions to fully closed, such that exhaust gas225will flow into cooling system240. Conversely, during shutdown, valve235may transition to fully open, while valve230transitions to fully closed. Cooling system240may cool exhaust gas225to produce cooled exhaust gas245. Cooling system240may comprise a direct contact cooler (DCC). Cooled exhaust gas245may flow from cooling system240and be split into at least two paths. For instance, cooled exhaust gas245may be split into a first path to an oxygen mixer250and a second path to a carbon-capture system260, according to a set or controlled ratio (e.g., 45% to oxygen mixer250, and 55% to carbon-capture system260). Oxygen mixer250may mix cooled exhaust gas245with oxygen to produce recirculated exhaust gas255, which, as mentioned above, is mixed with inlet gas215in mixer box300to produce mixed gas305as working fluid F for gas turbine engine100. Carbon-capture system260may capture and store, sequester, or use (e.g., for fracking) carbon dioxide within cooled exhaust gas245. It should be understood that this recirculation of exhaust gas through closed system200may be continuous throughout operation of gas turbine engine100within closed system200. FIG.3illustrates a perspective view of mixer box300, according to an embodiment. Mixer box300is illustrated and described herein with respect to a set of axes X, Y, and Z. In the closed system200, illustrated inFIG.2, the X axis of mixer box300is parallel to longitudinal axis L of gas turbine engine100, and the upstream and downstream directions are the same for mixer box300as for gas turbine engine100. However, it should be understood that the X axis of mixer box300may be oriented in any manner, relative to longitudinal axis L of gas turbine engine100, and/or the upstream and downstream directions of mixer box300may differ from the upstream and downstream directions of gas turbine engine100, depending on the particular design goals and constraints. Mixer box300may comprise a first duct310forming a first flow path for inlet gas215along the X axis, and a second duct320forming a second flow path for recirculated exhaust gas255along the Y axis. For example, first duct310may comprise a cuboid with open sides (i.e., in Y-Z planes) on opposing ends along the X axis, representing the upstream end and downstream end of first duct310with respect to the first flow path for inlet gas215. Similarly, second duct320may comprise a cuboid with open sides (i.e., in X-Z planes) on opposing ends along the Y axis, representing the upstream end and downstream end of second duct320with respect to the second flow path for recirculated exhaust gas255. One of these open sides of second duct320may face one or a plurality of openings in a side (i.e., in an X-Z plane) of first duct310that is perpendicular to the Y axis, such that the second flow path for recirculated exhaust gas255flows into the first flow path for inlet gas215. First duct310and second duct320may be formed as two separate ducts (e.g., from the same material or different materials) that are permanently fixed to each other (e.g., via welding) or detachably fixed to each other (e.g., via nuts and bolts, screws, and/or other fastening means) in the described configuration. Alternatively, first duct310and second duct320could be formed as a single integral duct (e.g., from the same material). First duct310may house one or a plurality of mixers400. In the illustrated embodiment, first duct310houses three mixers400. However, first duct310may house any number of mixers400, depending on the particular design goals and constraints, including one mixer400, two mixers400, four mixers400, and so on. Each mixer400may be a cuboid structure that extends along the X axis between the two open upstream and downstream ends of first duct310, and along the Y axis from a first side of first duct310to which second duct320is affixed to an opposing second side of first duct310. Each mixer400may have a hollow interior with an open end at the first side of first duct310that is aligned with an opening through the first side of first duct310that is within the second flow path through second duct320. Mixers400may be spaced (e.g., equidistantly) apart along the Z axis, such that cuboid channels315are formed between adjacent mixers400and/or between a mixer400and a side of first duct310that is within an X-Y plane. Each mixer400may comprise a leading surface410facing in an upstream direction of first duct310, a trailing surface420facing in a downstream direction of first duct310, and two side surfaces430extending between leading surface410and trailing surface420. Each trailing surface420may comprise at least one aperture422. Preferably, each trailing surface420comprises a plurality of apertures422, illustrated as apertures422A,422B, to422N, aligned in at least one dimension along the Y axis. Similarly, each side surface430may comprise at least one aperture432. Preferably, each side surface430comprises a plurality of apertures432, illustrated as apertures432A,432B, to432N, aligned in two dimensions along both the X and Y axes. While a certain arrangement of apertures422and432are illustrated, it should be understood that other arrangements are possible, such as, for example, two dimensions of apertures422through trailing surface420along both the Y and Z axes. In any case, each aperture422and432forms a flow path between the hollow interior of mixer400, such that the hollow interior of mixer400is in fluid communication with the exterior of mixer400, including channels315. Second duct320may house one or a plurality of fairings330. In the illustrated embodiment, second duct320houses two fairings330. However, second duct320may house any number of fairings330, depending on the particular design goals and constraints, including one fairing330, three fairings330, four fairings330, and so on. Each fairing330may comprise a generally U-shaped or V-shaped structure, with a particular profile corresponding to desired aerodynamics, and with a vertex that faces the open end of second duct320that is opposite the end of second duct320that is affixed to first duct310. Thus, each fairing330acts to split the flow path of a gas entering the open end of second duct320into two separate flow paths325. In the illustrated embodiment, two fairings330split the flow path into three separate flow paths325. Each flow path325may correspond to one mixer400in first duct310. In other words, the side of first duct310to which second duct320is affixed may comprise, for each flow path325, an opening that is aligned with both that flow path325and an open end of one of mixers400. Consequently, gas flowing along a flow path325flows through the aligned opening and into the aligned mixer400. Thus, it should be understood that the number of mixers400, the number of openings in the side of first duct310to which second duct320is affixed, and the number of channels325, in mixer box300, may all be the same. In addition, this number may be one more than the number of fairings330in mixer box300. FIG.4illustrates a cross-sectional perspective view of mixer box300, cut in an X-Z plane, according to an embodiment. As illustrated, leading surface410of mixer400may be generally U-shaped or V-shaped, with a profile corresponding to desired aerodynamics, and with a vertex that faces the open upstream end of first duct310. Thus, leading surface410acts to split the flow path of inlet gas215entering the upstream end of first duct310into two separate channels315with a mixer400between each pair of adjacent channels315. In other words, inlet gas215is split into separate channels315to flow between mixers400. In the illustrated embodiment, three leading surfaces410of three mixers400split the flow path into four separate channels315. Each mixer400may comprise one or a plurality of baffles450that divide the hollow interior of mixer400into distinct channels or columns that extend along the Y axis. In the illustrated embodiment, each mixer400comprises four baffles450, thereby dividing the hollow interior of mixer400into four distinct channels. Notably, the hollow region formed by leading surface410and the forward-most baffle450is not considered a channel, because, in the illustrated embodiments, this hollow region is fully enclosed with no inlet or outlet. However, in an alternative embodiment, this hollow region could comprise an inlet and/or one or more outlets, so as to form a channel that may act in the same or similar manner as the other channels within mixer400. FIG.5illustrates a cross-sectional perspective view of mixer box300, cut in a Y-Z plane, according to an embodiment. Each fairing330splits a flow path of recirculated exhaust gas255into two separate flow paths325. Each flow path325is aligned with an opening312in the side of first duct310to which second duct320is affixed. In addition, each mixer400is aligned with one of these openings312. Thus, recirculated exhaust gas255is split into separate flow paths325to flow through openings312in first duct310into the hollow interiors of mixers400. In an embodiment in which each mixer400comprises baffles450, recirculated exhaust gas255is further divided into the separate channels formed by baffles450within the hollow interior of mixer400. Notably, the use of baffles450to divide the hollow interior of mixer400helps to prevent the formation of a vortex within mixer400. A vortex could cause an area of low pressure within the hollow interior of mixer400, which may cause gas from the exterior of mixer400to flow into the hollow interior of mixer400, referred to as “ingress,” via apertures422and/or432. As illustrated, each mixer400may be open on the end that abuts the side of first duct310that comprises openings312, such that recirculated exhaust gas255may flow into the hollow interior of each mixer400through the open end of mixer400. In addition, each mixer400may comprise a base plate440on the end of mixer400that is opposite the open end of mixer400, along the Y axis. In an alternative embodiment, base plate440may be omitted, since the end of mixer400that would otherwise have base plate440may instead be closed by the side of first duct310. However, the use of base plate440may facilitate fastening of mixer400to first duct310, for example, via welding. FIG.6illustrates a perspective view of a single mixer400in isolation, according to an embodiment. As illustrated, apertures422in trailing surface420may have larger areas (e.g., diameters) closer to the open end of mixer400and smaller areas (e.g., diameters) closer to the closed end of mixer400, having base plate440. In particular, the area of apertures422may gradually decrease from the open end to the closed end. For example, aperture422A has the largest area, aperture422N has the smallest area, and apertures422between aperture422A and aperture422N, such as aperture422B, have smaller areas than aperture422A, but larger areas than aperture422N. While apertures422are described as gradually decreasing in area, two or more apertures422from the open end to the closed end may have the same areas, and/or the areas of apertures422may decrease from the open end to the closed end at a non-uniform or non-gradual rate. The decreasing areas of apertures422from the open end to the closed end of mixer400promotes more uniform mixing by biasing the areas of apertures422towards apertures422near the open end of mixer400. This compensates for the crossflow phenomenon that diminishes the flow of recirculated exhaust gas255through apertures422at the open end of mixer400, relative to apertures422at the closed end of mixer400. Similarly and for the same reasons, apertures432in each side surface430may have larger areas (e.g., diameters) closer to the open end of mixer400and smaller areas (e.g., diameters) closer to the closed end of mixer400, having base plate440. In particular, the area of apertures432may gradually decrease from the open end to the closed end. For example, aperture432A has the largest area, aperture432N has the smallest area, and apertures432between aperture432A and aperture432N, such as aperture432B, have smaller areas than aperture432A, but larger areas than aperture432N. While apertures432are described as gradually decreasing in area, two or more apertures432from the open end to the closed end may have the same areas, and/or the areas of apertures432may decrease from the open end to the closed end at a non-uniform or non-gradual rate. As illustrated, apertures432may be formed in two dimensions through each side surface430. In this case, each column of apertures432, extending from the open end to the closed end of mixer400, may have the same configuration of apertures432. Thus, every aperture432in each row of apertures432, extending from leading surface410to trailing surface420, may have the same area. While four columns of apertures432and six rows of apertures432are illustrated, it should be understood that side surface430may comprise any number of columns and rows of apertures432, depending on the particular design goals and constraints. In addition, while trailing surface420is illustrated with only a single column of apertures422, trailing surface420could be configured with multiple columns of apertures422in a similar or identical manner as side surface430. In the illustrated embodiment, each column of apertures432in each side surface430is identical in terms of the number, arrangement, and areas of apertures432. In addition, the column of apertures422is identical, in terms of the number, arrangement, and areas of apertures422, as each column of apertures432. In an alternative embodiment, each column of apertures432, within each side surface430, may have different numbers, arrangements, and/or areas of apertures432than one or more other columns of apertures432in the same side surface430and/or different side surfaces430. Additionally or alternatively, each column of apertures422, within each trailing surface420, may have different numbers, arrangements, and/or areas of apertures422than one or more columns in the same trailing surface420and/or different trailing surfaces420and/or one or more columns of apertures432in one or more side surfaces430. Between each pair of adjacent columns of apertures432through each side surface430a plurality of plug-weld holes434may be formed. In the illustrated embodiment, a set of two staggered lines of plug-weld holes434are formed between each adjacent column of apertures432. However, in alternative embodiments, fewer or more lines of plug-weld holes434may be formed and/or a different arrangement of plug-weld holes434may be formed between adjacent columns of apertures432. Plug-weld holes434are aligned with the sides of baffles450within the hollow interior of mixer400, such that baffles450may be welded to side surfaces430through plug-weld holes434. In addition, each side surface430may comprise one or a plurality of drainage holes436, along the edge of side surface430that abuts base plate440. Each drainage hole436may align with a channel (e.g., the center of the channel) formed within the hollow interior of mixer400by baffle(s)450. Thus, in the illustrated embodiment, a drainage hole436is formed at the base of each column of apertures432, since each column corresponds to one of the channels within the hollow interior of mixer400. Since the gas within mixer box300may be very humid, condensate may form with the hollow interior of mixer400. Each drainage hole436enables condensate that forms within a respective channel to flow out of the hollow interior of mixer400into channels315, so that the condensate does not collect within mixers400. Rather, the condensate exits mixers400via drainage holes436and is reintroduced into the gases mixing within channels315. In an embodiment, the surface of base plate440within the hollow interior of mixer400could be contoured, creased, grooved, or otherwise configured to guide condensate to drainage holes436. Alternatively, mixer400may rely solely on the pressure differential between the interior and exterior of mixer400to force condensate out of drainage holes436. FIG.7illustrates a perspective view of leading surface410in isolation, according to an embodiment. As illustrated, leading surface410may have a generally U-shaped or V-shaped profile. Leading surface410may be formed from a single material that is bent to the desired curvature. The long edges of leading surface410may be welded or otherwise affixed to respective side surfaces430. FIG.8illustrates a perspective view of trailing surface420in isolation, according to an embodiment. As illustrated, trailing surface420may comprise a substrate424, comprising apertures422(e.g.,422A,422B, . . .422N), with two side portions426A and426B on each long side of substrate424. Substrate424and side portions426A and426B may be integrally formed from a single piece of material, or may be formed as separate pieces of material that are joined together in any suitable manner. Trailing surface420may be welded or otherwise affixed to respective side surfaces430at side portions426A and426B. FIG.9illustrates an elevation view of side surface430in isolation, according to an embodiment. It should be understood that each mixer400may comprise two identical side surfaces430. As discussed elsewhere herein, each side surface430may comprise a plurality of columns of apertures432(e.g.,432A,432B, . . .432N). Each column of apertures432, which will align with channels within the hollow interior of mixer400, may also comprise a drainage hole436, formed as a notch within an edge of side surface430that will be affixed to base plate440. In addition, at least one line of plug-weld holes434may be formed between adjacent columns of apertures432, so as to align with a respective baffle450within the hollow interior of mixer400. In the illustrated embodiment, two staggered lines of plug-weld holes434are provided for each baffle450. It should be understood that a baffle450may be welded to side surface430by aligning the baffle450with a set of plug-weld holes434, and welding through the plug-weld holes434. FIG.10illustrates a perspective view of base plate440in isolation, according to an embodiment. As illustrated, base plate440may comprise a generally rectangular portion444that has a profile that corresponds to the profile of an assembly including trailing surface420and two side surfaces440, and a generally U-shaped or V-shaped portion446that has a profile that corresponds to the profile of leading surface410. In other words, base plate440has a profile that matches the profile of mixer400in an X-Z plane, so as to fully close one end of mixer400along the Y axis. FIG.11illustrates a perspective view of baffle450in isolation, according to an embodiment. As illustrated, baffle450may comprise a substrate454, with two side portions456A and456B on each long side of substrate454. Substrate454and side portions456A and456B may be integrally formed from a single piece of material, or may be formed as separate pieces of material that are joined together in any suitable manner. Baffle450may be welded or otherwise affixed between a pair of side surfaces430at side portions456A and456B (e.g., by welding through corresponding plug-weld holes434through side surfaces430). It should be understood that each baffle450may be identical. FIG.12illustrates a perspective view of first duct310in isolation, according to an embodiment. As illustrated, flanges316(e.g.,316A and316B) are formed around both open ends of first duct310to facilitate joining of first duct310within a duct system of closed system200. In particular, leading flange316A may be affixed (e.g., permanently via welding, or detachably via nuts and bolts, screws, etc.) to a corresponding flange on a duct that supplies inlet gas215, and trailing flange316B may be affixed (e.g., permanently via welding, or detachably via nuts and bolts, screws, etc.) to a corresponding flange on a duct that supplies mixed gas305as working fluid F to gas turbine engine100. The two open ends of first duct310form a primary flow path through first duct310, whereas openings312, through a side that is in a plane that is parallel to the primary flow path, form secondary flow paths into first duct310. In the illustrated embodiment, the primary and secondary flow paths meet at a perpendicular (i.e., 90-degree) angle. However, it should be understood that in alternative embodiments, the primary and secondary flow paths may be configured to meet at a non-perpendicular angle, for example, by adjusting the shape of first duct310, adjusting the shape of second duct320, adding additional components, and/or the like. First duct310may also comprise lines of plug-weld holes314on a side opposite openings312. In the illustrated embodiment, three lines of plug-weld holes314are formed in each of three sets, with each set corresponding to one mixer400. It should be understood that the number of sets of plug-weld holes314will be equal to the number of mixers400to be housed within first duct310(e.g., three in the illustrated example), and that the number of plug-weld holes314in each line and/or the number of lines of plug-weld holes314may be set to any suitable number. In any case, each mixer400may be aligned with a respective set of plug-weld holes314, and then welded to first duct310from the exterior of first duct310through plug-weld holes314. FIG.13illustrates a perspective view of fairing330in isolation, according to an embodiment. Each fairing330may be formed as a generally U-shaped or V-shaped structure334with flat portions336A and336B on either side. Curved structure334and flat portions326A and326B may be integrally formed from a single piece of material, or may be formed as separate pieces of material that are joined together in any suitable manner. Fairing330may be welded to second duct320at the edges of curved structure334and/or welded to the edges of openings312of first duct310at flat portions336A and336B. FIG.14illustrates a profile of mixer box300in the Y-Z plane (i.e., looking down the X axis), according to an embodiment. In an embodiment, the total area of channels315is greater than the total area of mixers400in this profile. For example, the total area of channels315may be 57% or more of the total cross-sectional area through mixer box300. In addition, each interior channel315, illustrated as interior channels315B and315C, may have twice the cross-sectional area as each outer channel315A and315D, since interior channels315B and315C receive twice the amount of recirculated exhaust gas255(i.e., from two side surfaces430of adjacent mixers400). FIG.15illustrates a perspective cross-sectional view of a portion of closed system200with mixer box300installed, according to an embodiment. During operation, inlet gas215, output by air inlet210, flows into first duct310of mixer box300along the X axis. It should be understood that the flow path of inlet gas215is split by leading surface410of each mixer400into channels315, such that inlet gas215flows between mixers400. Simultaneously, recirculated exhaust gas255, output by the exhaust recirculation system (e.g., output by oxygen mixer250), flows into second duct320of mixer box300along the Y axis. It should be understood that the flow path of recirculated exhaust gas255is split by fairings330into channels335, such that recirculated exhaust gas255flows through openings312in first duct310and into the hollow interiors of mixers400. Within the hollow interiors of mixers400, recirculated exhaust gas255may be further divided into channels formed by baffles450within each mixer400. As recirculated exhaust gas255flows through the hollow interiors of mixers400, recirculated exhaust gas255flows out of each mixer400through the column(s) of apertures422in trailing surface420and the column(s) of apertures432in side surfaces430. Apertures422and432may have greater areas at the open end of each mixer400than at the closed end of each mixer400, to produce a more uniform diffusion of recirculated exhaust gas255into inlet gas215flowing through channels315. Recirculated exhaust gas255, exiting apertures422and432, mixes with inlet gas215, flowing through channels315, to produce mixed gas305as the working fluid F that is input to gas turbine engine100. As illustrated, recirculated exhaust gas255(e.g., output by oxygen mixer250) may flow through a first length of duct1510before entering mixer box300. First length of duct1510may be configured to ensure that the oxygen, added by oxygen mixer260, is fully mixed into recirculated exhaust gas255, prior to entering mixer box300. In an embodiment, first length of duct1510may be a diffuser that widens from the upstream end towards the downstream connection to mixer box300, to slow the flow of recirculated exhaust gas255and to match the dimensions of the open end of second duct320in order to maximize the mixing potential within mixer box300. Similarly, mixed gas305may flow through a second length of duct1520after exiting mixer box300. Second length of duct1520may be configured to ensure that inlet gas215and recirculated exhaust gas255are fully mixed, prior to entering compressor120of gas turbine engine100. While the primary flow path through first duct310is described herein as a flow path for inlet gas215, and the secondary flow path through second duct320is described herein as a flow path for recirculated exhaust gas255, in an alternative embodiment, the flow paths could be switched. In this case, recirculated exhaust gas255may flow into the open upstream end of first duct310, whereas inlet gas215may flow through second duct320, through openings312, into mixers400, and out of apertures422and432. It should be understood that the other components of closed system200may be adapted to account for this different configuration of flow paths. Each of the components of mixer box300may be made of any suitable material. In an embodiment, the components are fabricated out of stainless steel, such as grade-304 stainless steel. However, it should be understood that the components may be fabricated from other materials, such as carbon steel. In addition, all of the components of mixer box300may be fabricated from the same material, or one or more components of mixer box300may be fabricated from a different material than one or more other components of mixer box300. INDUSTRIAL APPLICABILITY In a closed system200that recirculates exhaust gas225from a gas turbine engine100, recirculated exhaust gas255should be mixed with inlet gas215in a manner that does not create an excessive pressure drop, since an excessive pressure drop can be detrimental to the performance of gas turbine engine100. The performance of gas turbine engine100may also suffer if the distribution of gases within the resulting mixed gas305, entering gas turbine engine100, is not relatively uniform. This can be especially problematic when site constraints and/or other design constraints limit the duct length in which inlet gas215and recirculated exhaust gas255are mixed. Accordingly, a mixer box300is disclosed for efficient mixing of inlet gas215and recirculated exhaust gas255, to produce a mixed gas305with acceptably uniform distribution, within a short duct length and without an excessive pressure drop. Mixer box300is compact, such that existing closed systems200may be easily retrofitted with mixer box at the existing point of mixing. Alternatively, a closed system200may be constructed, in the first place, with mixer box300. Mixer box300produces a more uniform distribution in mixed gas305by virtue of mixers400. In particular, each mixer400extends the entire length of the Y axis between a first side and a second side of first duct310. Thus, as recirculated exhaust gas255flows through openings315in the first side of first duct310, recirculated exhaust gas255does not simply turn into the primary flow path through first duct310. Rather, because recirculated exhaust gas255is channeled into the hollow interiors of mixers400, the flow of recirculated exhaust gas255is forced to extend along the entire length of the Y axis between the first side and the second side of first duct310. In other words, the secondary flow path of recirculated exhaust gas255is forced perpendicular to the primary flow path along the entire height of the primary flow path in the Y axis. In addition, mixers400may extend the entire length of first duct310, along the X axis, from the open upstream end to the open downstream end. Thus, the secondary flow path of recirculated exhaust gas255is also forced to extend the entire length of first duct310. This extension of the secondary flow path through the primary flow path along both the X and Y axes promotes more uniform mixing by providing more uniform injection of recirculated exhaust gas255into the flow path of inlet gas215. Furthermore, apertures422and432, which provide flow paths from the hollow interior to the exterior of each mixer400, may have areas that increase in area from the closed end to the open end of each mixer400. This increases the volume of recirculated exhaust gas255that is ejected from the apertures422/432that are closer to the open end of mixer400, relative to apertures422/432that are closer to the closed end of mixer400, in order to compensate for the natural bias of recirculated exhaust gas255to remain in the secondary flow path until reaching the closed end of mixer400. Thus, the volume of recirculated exhaust gas255that is ejected from apertures422/432is more uniform across the entire length of mixer400along the Y axis, to again promote more uniform mixing by providing more uniform injection of recirculated exhaust gas255into the flow path of inlet gas215. In addition, each mixer400may comprise baffles450that divide the hollow interior into channels. The separation of the hollow interior of each mixer400into these channels helps to prevent the formation of a vortex within the hollow interior of mixer400. Such a vortex may create a low-pressure area within mixer400, which could cause an ingress of gas into mixer400. Thus, baffles450also promote more uniform mixing by facilitating higher pressure within the hollow interior of mixer400. Unless explicitly excluded, the use of the singular to describe a component, structure, or operation does not exclude the use of plural such components, structures, or operations, or their equivalents. The use of “a”, “an”, “the”, “at least one”, “one or more,” and similar terms in the disclosure (especially in the context of the appended claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by the context. The use of the term “at least one” or “one or more of” followed by a list of one or more items (e.g., “at least one of A and B” or “one or more of A and B”) is to be construed to mean one item selected from the listed items (e.g., A only, or B only) or any combination of two or more of the listed items (e.g., A and B; A, A, and B; A, B, and B; A and A; B and B; and so on), unless otherwise indicated herein or clearly contradicted by the context. Similarly, as used herein, the word “or” refers to any possible permutation of a set of items. For example, the phrase “A, B, or C” refers to at least one of A, B, or C, or any combination thereof, such as any of: A; B; C; A and B; A and C; B and C; A, B, and C; or a plurality of any item, such as A and A; B, B, and C; A, A, B, C, and C; and so on. It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. Aspects described in connection with one embodiment are intended to be able to be used with the other embodiments. Any explanation in connection with one embodiment applies to similar features of the other embodiments, and elements of multiple embodiments can be combined to form other embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. The preceding detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. The described embodiments are not limited to usage in conjunction with a particular type of machine. Hence, although the present embodiments are, for convenience of explanation, depicted and described as being implemented in a closed system with a gas turbine engine, it will be appreciated that it can be implemented in various other types of systems in which gases are mixed, and with various other types of machines in various other environments. Furthermore, there is no intention to be bound by any theory presented in any preceding section. It is also understood that the illustrations may include exaggerated dimensions and graphical representation to better illustrate the referenced items shown, and are not considered limiting unless expressly stated as such. | 41,636 |
11859545 | DETAILED DESCRIPTION FIG.1is schematic illustration of a propulsion system20for an aircraft. Briefly, the aircraft may be an airplane, a drone (e.g., an unmanned aerial vehicle (UAV)) or any other manned or unmanned aerial vehicle. The aircraft propulsion system20includes a gas turbine engine22and a nacelle24. The gas turbine engine22may be configured as a turbofan engine. The gas turbine engine22ofFIG.1, for example, includes a fan section26, a compressor section28, a combustor section30and a turbine section32. The compressor section28may include a low-pressure compressor (LPC) section28A and a high-pressure compressor (HPC) section28B. The turbine section32may include a high-pressure turbine (HPT) section32A and a low-pressure turbine (LPT) section32B. The engine sections26,28,30, and32may be arranged sequentially along an axial centerline34(e.g., a rotational axis) of the gas turbine engine22within an aircraft propulsion system housing36. This propulsion system housing36includes an outer housing structure38and an inner housing structure40. The outer housing structure36includes an outer case42(e.g., a fan case) and an outer structure44of the nacelle24; e.g., an outer nacelle structure. The outer case42houses at least the fan section26. The outer nacelle structure44houses and provides an aerodynamic cover for the outer case42. The outer nacelle structure44also covers a portion of an inner structure46of the nacelle24; e.g., an inner nacelle structure, which may also be referred to as an inner fixed structure (IFS). More particularly, the outer nacelle structure44axially overlaps and extends circumferentially about (e.g., completely around) the inner nacelle structure46. The outer nacelle structure44and the inner nacelle structure46thereby at least partially or completely form a (e.g., annular) bypass flowpath48within the aircraft propulsion system20. The inner housing structure40includes an inner case50(e.g., a core case) and the inner nacelle structure46. The inner case50houses one or more of the engine sections26,28,30, and32, which engine sections26,28,30, and32may be collectively referred to as an engine core. The inner nacelle structure46houses and provides an aerodynamic cover for the inner case50. Each of the engine sections26,28A,28B,32A, and32B includes a bladed rotor52,54,56,58, and60. The fan rotor52and the LPC rotor54are connected to and driven by the LPT rotor56through a low-speed shaft. The HPC rotor58is connected to and driven by the HPT rotor60through a high-speed shaft. The shafts are rotatably supported by a plurality of bearings (not shown). Each of these bearings is connected to the aircraft propulsion system housing36(e.g., the inner case50) by at least one stationary structure such as, for example, an annular support strut. During operation, air enters the aircraft propulsion system20through an aircraft propulsion system inlet structure62. This air is directed through an inlet duct64(e.g., a fan duct in the fan section26) and into a (e.g., annular) core flowpath66and the bypass flowpath48. The core flowpath66extends axially along the axial centerline34within the propulsion system20, through the engine sections28,30, and32, to a core nozzle outlet68, where the core flowpath66is radially within the inner case50. The bypass flowpath48extends axially along the axial centerline34within the propulsion system20to a bypass nozzle outlet70, where the bypass flowpath48is radially between the outer nacelle structure44and the inner nacelle structure46. The air within the core flowpath66may be referred to as “core air.” The air within the bypass flowpath48may be referred to as “bypass air.” The core air is compressed by the LPC rotor54and the HPC rotor58and directed into a combustion chamber72of a combustor74in the combustor section30. Fuel is injected into the combustion chamber72through one or more fuel injectors and mixed with the compressed core air to provide a fuel-air mixture. This fuel-air mixture is ignited and combustion products thereof flow through and sequentially cause the HPT rotor60and the LPT rotor56to rotate. The rotation of the HPT rotor60and the LPT rotor56respectively drive rotation of the HPC rotor58and the LPC rotor54and, thus, compression of the air received from a core airflow inlet76. The rotation of the LPT rotor56also drives rotation of the fan rotor52, which fan rotor52propels bypass air through and out of the bypass flowpath48. The propulsion system20of the present disclosure, however, is not limited to the exemplary gas turbine engine configuration described above. Optimal mass flow requirements of the air entering the propulsion system20through the aircraft propulsion system inlet structure62may change depending upon one or more parameters. These parameters may include, but are not limited to, modes of operation, aircraft maneuvers, and operating conditions. For example, where the aircraft flies at supersonic speeds, a first mass flow of the air may be directed through the aircraft propulsion system inlet structure62into the propulsion system20. When the aircraft flies at subsonic speeds, a second mass flow of the air may be directed through the aircraft propulsion system inlet structure62into the propulsion system20, where the second mass flow is greater than the first mass flow. To accommodate the changing mass flow requirements for the propulsion system20, the aircraft propulsion system inlet structure62is configured as a variable area inlet78. Referring toFIG.2, this variable area inlet78includes a stationary inlet structure80, a movable (e.g., translatable) inlet door82, an inner (e.g., central, primary) inlet passage84, and one or more outer (e.g., side, auxiliary) inlet passages86. Referring toFIGS.1and2, the inlet structure80may be configured as a duct or another tubular body. The inlet structure80ofFIGS.1and2, for example, has a tubular sidewall88. The inlet structure80and its sidewall88extend longitudinally along a longitudinal centerline90of the variable area inlet78to a leading edge92of the variable area inlet78(e.g., the inlet structure80). The longitudinal centerline90may be an extension of or coaxial with the axial centerline34. The inlet structure80and its sidewall88extend circumferentially about (e.g., completely around) around the longitudinal centerline90. The inlet structure80and its sidewall88extend radially between and to an inner side94of the inlet structure80and an outer side96of the inlet structure80. The inner inlet passage84extends longitudinally along the longitudinal centerline90within (e.g., through) the variable area inlet78and its inlet structure80from an inner inlet orifice98into the inner inlet passage84towards the gas turbine engine22and its fan section26(e.g., to the inlet duct64). The inner inlet passage84ofFIGS.1and2, for example, is configured as (or otherwise includes) an interior bore formed within the inlet structure80by the inlet structure inner side94. The inner inlet orifice98is disposed at (e.g., on, adjacent, or proximate) the leading edge92. The inner inlet orifice98ofFIGS.1and2, for example, is formed by an inner skin of an inlet lip (e.g., a nose lip) of the inlet structure80at the leading edge92. Referring toFIGS.3A-C, the inner inlet orifice98has an outer perimeter100(e.g., an outer periphery of a cross-sectional geometry) when viewed in a reference plane, for example, perpendicular to the longitudinal centerline90. Referring toFIG.3A, the outer perimeter100may have curvilinear shape; e.g., circular shape, oval shape, a splined ring shape, etc. Referring toFIG.3B, the outer perimeter100may alternatively have a D shape; e.g., a partially curvilinear and a partially polygonal shape. Referring toFIG.3C, the outer perimeter100may alternatively be polygonal shaped. The present disclosure, however, is not limited to the foregoing exemplary inner inlet orifice perimeter geometries. Referring toFIGS.2and4, the outer inlet passages86are disposed circumferentially about the longitudinal centerline90and the inner inlet passage84in an array (e.g., a circular array). Each of the outer inlet passages86ofFIG.2is aft and/or downstream of the leading edge92. Each of the outer inlet passages86, for example, is longitudinally spaced from the leading edge92and the inner inlet orifice98by a non-zero longitudinal distance. With such an arrangement, a portion (e.g., upstream and/or forward tubular portion) of the inlet structure80separates the inner inlet passage84from the outer inlet passages86. The outer inlet passages86are positioned relative to the fan rotor52so as to minimize flow distortion of air directed into the fan rotor52face (e.g., upstream-facing surfaces of the fan rotor52). Each of the outer inlet passages86may be configured as a port in the inlet structure80and its sidewall88. Each of the outer inlet passages86, for example, may extend through the inlet structure80to the inner inlet passage84. Each outer inlet passage86ofFIG.4, in particular, extends radially inward (e.g., in a direction towards the longitudinal centerline90) from an outer inlet orifice102into that respective outer inlet passage86, through the sidewall88, to an outer outlet orifice104from that respective outer inlet passage86. The outer inlet orifice102is disposed at and, more particularly, may be formed in a surface of the inlet structure80at its outer side96. The outer outlet orifice104is disposed at and, more particularly, may be formed in a surface of the inlet structure80at its inner side94. The outer outlet orifice104is adjacent an outer periphery of the inner inlet passage84. Each outer inlet passage86may thereby be (e.g., directly) fluidly coupled with the inner inlet passage84through the respective outer outlet orifice104. Referring toFIGS.1and2, the inlet door82extends circumferentially about (e.g., completely around) the longitudinal centerline90and the inner inlet passage84. For example, the inlet door82may be an annular inlet door. The inlet door82extends (e.g., axially extends) between and to a leading edge106of the inlet door82and a trailing edge108of the inlet door82. The inlet door82includes an outer side110(e.g., an outer radial side) extending between and to the leading edge106and the trailing edge108. The outer side110has an outer perimeter112(e.g., an outer periphery of a cross-sectional geometry) when viewed in a reference plane, for example, perpendicular to the longitudinal centerline90. The outer perimeter112may be the same as or substantially the same as the outer perimeter100. For example, the outer perimeter112may have a curvilinear shape, a partially curvilinear and a partially polygonal shape, a polygonal shape, etc., and the present disclosure is not limited to the foregoing exemplary outer perimeter112geometries. The inlet door82is configured to move between a closed (e.g., stowed, forward, and/or supersonic) position and an open (e.g., deployed, aft, and/or subsonic) position; see alsoFIGS.5and6. The inlet door82, may be movably mounted to the inlet structure80, or alternatively to another (e.g., fixed) structure of the propulsion system20, and configured to translate (e.g., axially translate) relative to the inlet structure80, or alternatively to another (e.g., fixed) structure of the propulsion system20. The inlet door82may thereby translate axially along the longitudinal centerline90from the closed position ofFIGS.1and5to the open position ofFIGS.2and6. With such an arrangement, the variable area inlet78may reduce or eliminate overhung mass in both the closed and open positions compared to known variable area inlets. With the inlet door82in its closed (e.g., fully closed) position ofFIGS.1and5, the inlet door82is configured to close (e.g., cover, plug, or otherwise obstruct and/or seal off) each of the outer inlet passages86and each respective outer inlet orifice102. In this closed position, the outer side110may be disposed coincident with the outer side96. In this closed position, the leading edge106may contact (e.g., sealingly contact) or otherwise be disposed at (e.g., on, adjacent, or proximate) the tubular sidewall88. With the variable area inlet78in this closed-door arrangement, the variable area inlet78may have a first inlet area that is equal to (e.g., only including) an inlet area of the inner inlet orifice98. The gas turbine engine22and its flowpath(s)48and/or66(seeFIG.1) may thereby (e.g., only) receive incoming air from the inner inlet orifice98. In contrast, with the inlet door82in its open (e.g., fully open) position ofFIGS.2and6, the inlet door82is configured to open (e.g., uncover, unplug, or otherwise facilitate access to) each of the outer inlet passages86and each respective outer inlet orifice102. In this open position, the leading edge106may be axially displaced from the outer inlet passages86. For example, in the open position, the leading edge106may be disposed axially aft of the outer inlet passages86. With the variable area inlet78in this open-door arrangement, the variable area inlet78may have a second (e.g., greater) inlet area that is equal to the inlet area of the inner inlet orifice98plus inlet areas of the open outer inlet orifices102. The gas turbine engine22and its flowpath(s)48and/or66(seeFIG.2) may thereby receive incoming air from each (e.g., open) outer inlet passage86and its outer inlet orifice102in addition to the incoming air from the inner inlet orifice98. Thus, by moving (e.g., translating) between the closed position ofFIGS.1and5and the open position ofFIGS.2and6, the variable area inlet78and its inlet door82may selectively change the incoming air mass flow into the propulsion system20. While operation of the inlet door82is discussed above as moving between the closed (e.g., fully closed) position and the open (e.g., fully open) position (e.g., seeFIGS.1and2), the inlet door82may also (or may not) move to and stop (or otherwise pause) at one or more intermediate positions (e.g., partially open positions) between the closed position and the open position. In this manner, the variable area inlet78may tailor the incoming air mass flow based on different conditions, aircraft speeds, maneuvers, etc. The inlet door82may be translated or otherwise moved between its open position and its closed position via one or more actuators (not shown). The actuator(s) may be electric motor(s), pneumatic drive(s), and/or hydraulic cylinder(s). These actuator(s), for example, may be linear actuators. In some embodiments, the inlet door82may be configured with one or more locks (e.g., dedicated locks) to lock the inlet door82(e.g., the leading edge106or an upstream portion of the inlet door82) into one or more positions; e.g., the open position, the closed position, and/or one or more intermediate positions. In addition or alternatively, the actuator(s) may include one or more integral locks for maintaining the position of the inlet door82. In some embodiments, referring toFIG.7, the propulsion system20may be arranged exterior of an airframe114of the aircraft. The propulsion system20, for example, may be located outside of the aircraft airframe114, and mounted to an exterior of the aircraft airframe114. The aircraft propulsion system20ofFIG.7, in particular, is mounted to a component116of the aircraft airframe114by a mount118(e.g., a pylon). Examples of the airframe component116include, but are not limited to, a wing and a fuselage. With such an arrangement, the variable area inlet78is configured discrete (e.g., remote, spaced, etc.) from the aircraft airframe114and its airframe component116. The outer inlet passages86may thereby be distributed (e.g., uniformly, symmetrically, etc.) about the centerline34,90. The gas turbine engine22and its fan section26(seeFIG.2) may thereby receive a relatively even distribution of incoming air. In some embodiments, a command to open or close the inlet door82may be provided with one or more redundancies and/or safety measures. The command may be issued (e.g., generated) using an open-loop control system or a closed-loop control system. Movement of the inlet door82may be triggered based on one or more parameters. Examples of these parameters include, but are not limited to: position of the aircraft (e.g., on ground, in air); airspeed of the aircraft; fan pressure input; aircraft speed; and operator input (e.g., a command from a pilot). Actuation of the inlet door82may also or alternatively be based on system health. For example, if it is determined the inlet door82cannot close, the control system may prevent (or warn against) operating the aircraft at certain or any supersonic speeds. Conversely, if it is determined the inlet door82cannot open, the control system may prevent (or warn against) proceeding to takeoff where the aircraft is still on ground. The aircraft propulsion system20and its variable area inlet78may be configured with various gas turbine engines other than the exemplary one described above with respect toFIGS.1and2. The gas turbine engine, for example, may be configured as a geared engine or a direct drive engine. The gas turbine engine may be configured with a single spool, with two spools (e.g., seeFIGS.1and2), or with more than two spools. The gas turbine engine may be configured as a turbofan engine, a turbojet engine or any other type of turbine engine. The present disclosure therefore is not limited to any particular types or configurations of gas turbine engines. The present disclosure is also not limited to applications where the aircraft is capable to traveling supersonic speeds. The variable area inlet78, for example, may be utilized at subsonic speeds to, for example, increase ram air intake for certain flight conditions and/or aircraft maneuvers. While the principles of the disclosure have been described above in connection with specific apparatuses and methods, it is to be clearly understood that this description is made only by way of example and not as limitation on the scope of the disclosure. Specific details are given in the above description to provide a thorough understanding of the embodiments. However, it is understood that the embodiments may be practiced without these specific details. It is noted that the embodiments may be described as a process which is depicted as a flowchart, a flow diagram, a block diagram, etc. Although any one of these structures may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be rearranged. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc. The singular forms “a,” “an,” and “the” refer to one or more than one, unless the context clearly dictates otherwise. For example, the term “comprising a specimen” includes single or plural specimens and is considered equivalent to the phrase “comprising at least one specimen.” The term “or” refers to a single element of stated alternative elements or a combination of two or more elements unless the context clearly indicates otherwise. As used herein, “comprises” means “includes.” Thus, “comprising A or B,” means “including A or B, or A and B,” without excluding additional elements. It is noted that various connections are set forth between elements in the present description and drawings (the contents of which are included in this disclosure by way of reference). It is noted that these connections are general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. Any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. No element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprise”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. While various inventive aspects, concepts and features of the disclosures may be described and illustrated herein as embodied in combination in the exemplary embodiments, these various aspects, concepts, and features may be used in many alternative embodiments, either individually or in various combinations and sub-combinations thereof. Unless expressly excluded herein all such combinations and sub-combinations are intended to be within the scope of the present application. Still further, while various alternative embodiments as to the various aspects, concepts, and features of the disclosures—such as alternative materials, structures, configurations, methods, devices, and components, and so on—may be described herein, such descriptions are not intended to be a complete or exhaustive list of available alternative embodiments, whether presently known or later developed. Those skilled in the art may readily adopt one or more of the inventive aspects, concepts, or features into additional embodiments and uses within the scope of the present application even if such embodiments are not expressly disclosed herein. For example, in the exemplary embodiments described above within the Detailed Description portion of the present specification, elements may be described as individual units and shown as independent of one another to facilitate the description. In alternative embodiments, such elements may be configured as combined elements. | 21,993 |
11859546 | DETAILED DESCRIPTION Features, advantages, and embodiments of the present disclosure are set forth or apparent from a consideration of the following detailed description, drawings, and claims. Moreover, it is to be understood that the following detailed description is exemplary and intended to provide further explanation without limiting the scope of the disclosure as claimed. Various embodiments are discussed in detail below. While specific embodiments are discussed, this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without departing from the spirit and the scope of the present disclosure. As noted above, oil used to lubricate the gears of an epicyclical gear train may be expelled radially outward and collected by a gutter. The gutter may be circular and circumscribes the gears of the epicyclical gear train, such that the gutter is located radially outward of the gears. The oil collected by the gutter may be removed at a scavenge port. The amount of oil in the gutter varies based on the circumferential position. Relative to the direction of rotation of a rotor of the epicyclical gear train, such as a planetary gear unit, the amount of oil in the gutter is the least just after the scavenge port and then increases, in the direction of rotation of the rotor, to the scavenge port. This build-up of oil in the gutter can result in windage losses for the rotor and oil churn. The gutter may be sized based on the volume of the largest amount of oil to avoid such losses and churn. Sizing based on this criterion can increase the size of the gutter and the overall size of the gearbox, and leaves excess distance between the rotor and the gutter at positions of the gutter where the amount of oil is less. Instead of positioning the gutter concentrically with the epicyclical gear train, in the embodiments discussed herein, the center of the gutter is located eccentrically with the center of rotation of the epicyclical gear train. In these embodiments, the surface level of the oil in the gutter is more uniformly spaced from the rotor over the entire circumference of the gutter. Keeping the oil and the rotor distance uniform maintains a minimum distance to avoid oil churning and windage losses, but saves space and reduces the overall size of the gearbox by eliminating excess space where large distances between the surface level of the oil and rotor is not necessary but would occur in concentric gutter designs. The gutter designs discussed herein are suitable for use in gearboxes used in the engines of aircraft and, in particular, gas turbine engines.FIGS.1and2illustrate two gas turbine engines that may be used for propulsion of an aircraft. The gas turbine engine shown inFIG.1is a high bypass turbofan engine100. The gas turbine engine shown inFIG.2is a turboprop engine102. Both of the turbofan engine100and the turboprop engine102include a gearbox200having an eccentric gutter250according to the present disclosure, as will be discussed further below. Although the description below refers to the turbofan engine100and/or the turboprop engine102, the present disclosure is also applicable to wind turbines and turbo-machinery, in general, including, e.g., propfan gas turbine engines, turbojet gas turbine engines, and turboshaft gas turbine engines, including marine turbine engines, industrial turbine engines, and auxiliary power units. Moreover, the eccentric gutter arrangement may be used in any suitable gearbox including those having an epicyclical gear train. As shown inFIG.1, the turbofan engine100has an axial direction A (extending parallel to a longitudinal centerline104), a radial direction R, and a circumferential direction. The circumferential direction (not depicted inFIG.1) extends in a direction rotating about the longitudinal centerline104. The turbofan engine100may include an engine core106(also referred to as a turbomachine) and a fan assembly140. The engine core106may generally include, in serial flow arrangement, a compressor section110, a combustion section120, and a turbine section130. The compressor section110may define one or more compressors, such as, for example, a low-pressure compressor112and a high-pressure compressor114. The turbine section130may define one or more turbines, such as, e.g., a high-pressure turbine132and a low-pressure turbine134. In various embodiments, the compressor section110may further include an intermediate pressure compressor. In still other embodiments, the turbine section130may further include an intermediate pressure turbine. In wind turbine applications, the engine core106may generally be defined as one or more generators. The low-pressure compressor112and the high-pressure compressor114in the compressor section110and the high-pressure turbine132, and the low-pressure turbine134in the turbine section130, may each include one or more rotors. In one embodiment, the rotors include one or more shafts of the turbofan engine100connecting the compressor section110to the turbine section130. In other embodiments, the rotors generally define a disk extended at least partially in the radial direction R and a plurality of airfoils connected in a circumferentially adjacent arrangement and extended outward in the radial direction R from the disk. In one embodiment, the one or more rotors may each be connected together. For example, each rotor of the turbine section130or the compressor section110may be connected by mechanical fasteners, such as, e.g., bolts, nuts, screws, and/or rivets, or by a bonding process, such as, e.g., welding, friction bonding, diffusion bonding, etc. In various embodiments, one or more compressors of the compressor section110may be drivingly connected and rotatable with one or more turbines of the turbine section130by way of the one or more shafts. For example, the rotors of the low-pressure compressor112may be connected to and driven by the rotors of the low-pressure turbine134, by a low-pressure shaft122, and the rotors of the high-pressure compressor114may be connected to and driven by the rotors of the high-pressure turbine132, by a high-pressure shaft124. The fan assembly140generally includes a fan rotor142. The fan rotor142includes a plurality of blades144that are coupled to and extend outwardly from the fan rotor142in the radial direction R. In the embodiment shown inFIG.1, the fan rotor142may extend in the axial direction A toward a forward end from a reduction gearbox or a power gearbox200(herein referred to as “gearbox200”). The fan assembly140further includes a coupling shaft126coupled to the gearbox200and extended toward an aft end of the turbofan engine100. The coupling shaft126may couple the engine core106to the gearbox200. As shown inFIGS.1to3, the gearbox200of this embodiment includes an epicyclical gear train202including a sun gear210and a plurality of planet gears222. The sun gear210is axially installed onto and concentric to the coupling shaft126, such that the sun gear210is attached to, or integral to, the coupling shaft126. As will be discussed further below, the sun gear210is driven by the engine core106(receives a torque from the engine core106) to rotate about a rotational axis212, which, in this embodiment, is coincident with the longitudinal centerline104. The sun gear210includes a plurality of teeth that engage (or mesh with) a plurality of teeth formed on each of the plurality of planet gears222. A ring gear230(or annular gear) engages with the plurality of planet gears222and surrounds the plurality of planet gears222. More specifically, the ring gear230includes a plurality of teeth that engage (or mesh with) a plurality of teeth formed on each of the plurality of planet gears222. In this embodiment, the ring gear230is stationary. The plurality of planet gears222rotate, not only about a rotation axis224for each planet gear222, but the plurality of planet gears222also collectively rotate about the rotational axis212of the sun gear210. The planet gears222are rotatably connected to a carrier226, and the carrier226rotates about the rotational axis212of the sun gear210as the plurality of planet gears222collectively rotate. The plurality of planet gears222may be rotatably connected to the carrier226by various bearings (e.g., rollers, balls, or other bearing types, e.g., a journal bearing). The carrier226further connects to an output element to allow for rotation and transfer of power and torque from the sun gear210through the plurality of planet gears222. For example, the carrier226, may be coupled to or otherwise integral with the fan rotor142. Each planet gear222of the plurality of planet gears222engages with the sun gear210to be rotated by the sun gear210. Each planet gear222is configured to receive power and torque from the sun gear210. In other embodiments, the plurality of planet gears222may each be fixed such that the rotation axis224of each planet gear222is fixed relative to the sun gear210. In such an arrangement, the ring gear230rotates about the rotational axis212of the sun gear210, and the ring gear230connects to the output element, such as the fan rotor142, to allow for rotation and transfer of power and torque from the sun gear210through the plurality of planet gears222. The ring gear230engaging with each planet gear222of the plurality of planet gears222to be rotated by the plurality of planet gears222. The ring gear230is configured to receive power and torque from the plurality of planet gears222. In various embodiments, the gearbox200may further include additional planet gears disposed radially between the plurality of planet gears222and the sun gear210, or between the plurality of planet gears222and the ring gear230. The various gears may be various suitable gear designs, such as helical gears and, in the case of the planet gears222, may include step gears. As shown inFIG.1, the coupling shaft126is connected to the engine core106to transmit torque and power from the engine core106to the sun gear210, and through the epicyclical gear train202to the fan rotor142. The fan rotor142may be connected to the carrier226or the ring gear230to receive torque from the sun gear210, and to transfer torque to drive the fan assembly140. As power and torque are transmitted from the engine core106, the gearbox200provides power and torque at an output speed to the fan rotor142that is more suitably adjusted for the fan assembly140. For example, the gearbox200may reduce fan rotor142speed relative to the engine core106by a factor of two or more. According to one embodiment, the gearbox200reduces the rotational speed from the engine core106(e.g., the compressor section110or the turbine section130) and provides a desired amount of torque and rotational speed to the fan assembly140. During operation of the turbofan engine100, a volume of air (inlet air12), as indicated schematically by arrow12, enters the turbofan engine100. As the inlet air12passes across the fan blades144, a portion of the air (bypass air14), as indicated schematically by arrow14, is directed or routed outside of the engine core106to provide propulsion. Additionally, another portion of air, as indicated schematically by arrow22and referred to as core air22, is directed or routed through an associated inlet108into the compressor section110. The core air22is progressively compressed as it flows through the compressor section110, such as through the low-pressure compressor112and the high-pressure compressor114, toward the combustion section120. The now compressed air24(as indicated schematically by arrows24) flows into the combustion section120where a fuel is introduced, mixed with at least a portion of the compressed air24, and ignited to form combustion gases26. The combustion gases26flow into the turbine section130, causing rotary members of the turbine section130to rotate, and to support operation of respectively coupled rotary members in the compressor section110and/or the fan assembly140, as discussed above. As noted above,FIG.2shows a turboprop engine102that may be equipped with the gearbox200having the eccentric gutter arrangement. The discussion of the turbofan engine100shown inFIG.1also applies to the turboprop engine102shown inFIG.2. The same reference numerals are used for the same or similar components between the turbofan engine100and the turboprop engine102, and a detailed description of these components is omitted. In the arrangement, shown inFIG.2, the inlet108is located on the aft end of the turboprop engine102, and the core air22flows in a forward direction, but other arrangements of turboprop engine102may be used where the inlet108is located on the forward end of the turboprop engine102. Instead of a fan assembly140, the turboprop engine102includes a propeller assembly150. The propeller assembly150includes a plurality of propeller blades152that are coupled to and extend outwardly from a propeller shaft154in the radial direction R. As with the fan rotor142, the propeller shaft154is connected to the gearbox200to receive torque and power from the engine core106through the epicyclical gear train202. The propeller shaft154may be connected to the epicyclical gear train202in a similar manner to the fan rotor142as discussed above. FIG.3is a cross-sectional view of the gearbox200according to an embodiment. The cross-sectional view ofFIG.3is taken along line3-3shown inFIG.1. As discussed above, the gearbox200includes an epicyclical gear train202having a sun gear210, a plurality of planet gears222rotatably connected to a carrier226, and a ring gear230. Oil may be used to lubricate the rotating parts of the gearbox200, including the sun gear210, the planet gears222, and the ring gear230. An oil system240is configured to supply oil to the gearbox200. In this embodiment, the oil system240includes an oil pump242that draws oil from a reservoir244(or sump). The oil pump242pressurizes and drives the flow of oil to be injected by at least one oil nozzle246. Oil may be injected downstream (in the rotation direction) of a nip formed between meshing (engaging) gears. As shown inFIG.3, for example, the oil nozzle246is fluidly connected to the reservoir244and configured to inject oil in a nip formed between one of the planet gears222and the ring gear230. Only one oil nozzle246is shown inFIG.3, but a plurality of oil nozzles246may be used, such as, for example, at each of the nips formed between the planet gears222and the ring gear230. The nozzle246is preferably located upstream of the nip and injects oil in a direction toward the nip. Oil may be supplied to the epicyclical gear train202using other suitable supply devices and at other locations, including, for example, nips formed between the planet gears222and the sun gear210. As noted above, the plurality of planet gears222, together with the carrier226, collectively rotate about the rotational axis212of the sun gear210. The plurality of planet gears222, together with the carrier226, may be referred to as a rotor220herein. The ring gear230may be another example of a rotor in, for example, a configuration where the ring gear230rotates about the rotational axis212of the sun gear210instead of the plurality of planet gears222. As the rotor220rotates about the rotational axis212of the sun gear210, the oil is expelled outwardly by inertial (or centrifugal) forces and collected by a gutter250. The gutter250may be circular and circumscribes the gears of the epicyclical gear train202, such that the gutter250is located radially outward of the rotor220and, more specifically, the plurality of planet gears222and the carrier226. The gutter250is also located radially outward of the sun gear210. The gutter250is shown radially outward of the ring gear230, but, in some embodiments, particularly when the ring gear230is stationary, the gutter250may be formed integrally with the ring gear230. The gutter250is shown as having a U-shape in this embodiment, but the gutter250may have any shape suitable for collecting the oil therein. The gutter250includes a scavenge port252. The oil collected in the gutter250may be removed at the scavenge port252. The scavenge port252is located on a bottom portion of the gutter250so that gravity may assist in the flow of oil to the scavenge port252. The scavenge port252is fluidly connected to the reservoir244, and the oil is scavenged from the gutter250through the scavenge port252and returned to the reservoir244. The reservoir244, thus, is configured to receive oil from the scavenge port252. As discussed above, in a concentric arrangement of the gutter250and the rotor220, a distance between the gutter250and the rotor220is preferably sized based on the greatest amount of oil in the gutter250to avoid the oil level from getting close to the rotor (for example, the ring gear). When oil level rises to be close to the rotor, oil could be heavily disturbed and unintentionally picked up by the rotor. If the oil level continues to rise, part of a rim of the rotor could be submerged in the oil, which results in increasing of the drag on the rotor and thus large power loss. This phenomenon is referred to as oil churning. In order to avoid oil churning, one might consider increasing the distance between rotor and gutter, which increases the size of the gutter250and the overall size of the gearbox200but leaves excess distance between the rotor220and the gutter250at positions of the gutter where the amount of oil is less. Instead of positioning the gutter concentrically with the epicyclical gear train202, the gutter250may be located eccentrically with the epicyclical gear train202. FIGS.4and5are schematic diagrams used to illustrate the eccentric gutter250of this embodiment. The rotor220rotates in direction A about a rotation axis, which, in this embodiment, is the rotational axis212of the sun gear210. As noted above, the rotor220expels oil outwardly towards the gutter250, as illustrated by the arrows from the rotor220inFIG.4. As discussed above, the gutter250collects the expelled oil and the collected oil is removed by the scavenge port252. As noted above, the gutter250is circular having a center (gutter center254) and a radius (gutter radius Rg). In some embodiments, the gutter250may have variable radius in an axial direction of the gearbox200, and in these embodiments, the gutter radius Rg may be the minimum radius of the gutter250within the span of the width of the rotor220. The rotor220also has a radius (rotor radius Rr). In some embodiments, the rotor220may have variable radius across the width of the rotor220. In these embodiments, the rotor radius Rr may be the maximum radius of the rotor220within the span of the width of the rotor220, but the gutter radius Rg and the rotor radius Rr should be in the same cross-sectional plane within the span of the width of the rotor220. In the embodiment where the rotor220is the plurality of planet gears222collectively rotate together, the rotor radius Rr may be the maximum distance from the center of rotation to the edge of the rotating components. Note that the gutter radius Rg is larger than the rotor radius Rr. In the following discussion, the radial direction is a radial direction of the rotor taken from the rotational axis212. Likewise, an angular position θ is taken relative to a reference location in the direction of rotation. The reference location may be the center of the scavenge port252. When the scavenge port252is not circular, the center of the scavenge port252may be the center of the width of the port and at inner surface of the gutter250. The reference location has an angular position θ of zero. The angular position θ increases from zero in the direction of rotation A with a first quadrant being from zero to ninety degrees, a second quadrant being from ninety degrees to one hundred eighty degrees, a third quadrant being from one hundred eighty degrees to two hundred seventy degrees, and a fourth quadrant being from two hundred seventy degrees to three hundred sixty degrees. The gutter250is positioned eccentrically with respect to the rotor220. In this embodiment, the gutter250is positioned such that the rotor220is positioned farthest from the gutter250at angular positions θ having the most amount of oil, but closer to the gutter250at angular positions θ having less oil. The gutter center254may be offset in the radial direction of the rotor220. Where the gutter250is circular, the distance that the gutter center254is offset in the radial direction from the rotational axis212is the eccentricity distance (circular) ecirshown inFIG.5. In the arrangements discussed above, the gutter center254is preferably offset such that the gutter center254is in the fourth quadrant. The relative position of the gutter center254in terms of the angular position θ may be given by an eccentricity angle φ. The eccentricity angle φ may preferably be between two hundred seventy degrees and three hundred sixty degrees, and, more preferably, between three hundred ten degrees and three hundred fifty degrees. The position of the gutter250and, more specifically, the gutter center254may be characterized by an eccentricity ratio ε given by equation (1). ε=ecirCcir(1) In equation (1), eccentricity distance (circular) eciris the eccentricity distance (circular) discussed above, and centered clearance (circular) Cciris the difference between the gutter radius Rg and the rotor radius Rr (Ccir=Rg−Rr). Put another way, the eccentricity ratio ε is the ratio of the eccentricity distance e to the difference between the gutter radius Rg and the rotor radius Rr. Based on experimental testing, the eccentricity ratio ε is preferably from two thousandths to seventy-six hundredths and, more preferably, from four thousandths to thirty-eight hundredths. FIG.6is a schematic diagram used to illustrate another gutter250arrangement. In the embodiment shown inFIGS.4and5, the gutter250is circular, but the gutter may have other shapes. The gutter250may have an elliptical shape as shown inFIG.6. In the gutter shown inFIG.6, the gutter center254is the center of the ellipse. The gutter250, and more specifically, the gutter center254may be offset in a manner similar to the gutter250discussed above with respect toFIGS.4and5. FIG.7is a schematic diagram used to illustrate a further gutter250arrangement. In this embodiment, the gutter250has an irregular shape with the distance G between the rotor220and the gutter250(a gap G) variable (not constant) over the three hundred sixty degrees (angular positions θ) around the center of the rotor220(rotational axis212). The distance from the center of the rotor220(rotational axis212) to the gutter250may also be variable (not constant) over the three hundred sixty degrees (angular positions θ) around the center of the rotor220(rotational axis212). In some embodiments, gutter distance Dg is the distance from the center of the rotor220(rotational axis212) to the gutter250at a given angular position θ, and the gap G may be calculated as the difference between the gutter distance Dg and the rotor radius Rr (G=Dg−Rr). In some embodiments, the gap G increases with increasing angular position θ. The gutter distance Dg may have a maximum gutter distance Dgmaxand a minimum gutter distance Dgmin. The irregular shaped gutter250or the elliptical shaped gutter250may also have an eccentricity ratio ε given by equation (2). ε=eirrCirr(2) In equation (2), the eccentricity distance (irregular) eirris given by equation (3) and the centered clearance (irregular) Cirris given by equation (4). eirr=(Dgmax-Dgmin)2(3)Cirr=(Dgmax+Dgmin)2-Rr(4) Based on experimental testing, the eccentricity ratio ε for the non-circular embodiments also is preferably from two thousandths to seventy-six hundredths and, more preferably, from four thousandths to thirty-eight hundredths. FIG.8is a schematic diagram illustrating another gearbox200arrangement. In the embodiments discussed above, the scavenge port252is located in the gutter250, but the embodiments discussed herein may be applicable to other gearbox200arrangements. An alternative gearbox200arrangement is shown inFIG.8. In this embodiment the gutter250includes a plurality of gutter openings256around the circumference of the gutter250. Each gutter opening256allows oil to flow out of the gutter250into a cavity204formed between the gutter250and an outer casing206of the gearbox200. In this embodiment, the scavenge port252is located in the outer casing206and, more specifically on a bottom portion of the outer casing206so that gravity may assist in the flow of oil to the scavenge port252. Further aspects of the present disclosure are provided by the subject matter of the following clauses. A gearbox including an oil system, a rotor, and a gutter. The oil system is configured to supply oil to the gearbox. The rotor is rotatable about a rotational axis in a rotational direction. The rotor has a radial direction and expels oil radially outward when the rotor rotates. The gutter is positioned radially outward of the rotor in the radial direction of the rotor to collect oil expelled by the rotor when the rotor rotates. A radial distance from the rotational axis of the rotor to the gutter is variable in the rotational direction. The gearbox of the preceding clause, wherein the gutter includes a scavenge port. The oil system includes (i) a reservoir fluidly connected to the scavenge port and configured to receive oil from the scavenge port and (ii) at least one oil nozzle fluidly connected to the reservoir and configured to supply oil to the gearbox. The gearbox of any preceding clause, wherein the gutter is positioned eccentrically with respect to the rotor. The gearbox of any preceding clause, wherein the gutter has (i) a maximum distance from the rotational axis to the gutter (Dgmax), (ii) a minimum distance from the rotational axis to the gutter (Dgmin), and (iii) an eccentricity ratio (ε) from two thousandths to seventy-six hundredths. The eccentricity ratio (ε) is the ratio of an eccentricity distance (e) to a centered clearance (C). The eccentricity distance (e) is given by the following formula: e=(Dgmax−Dgmin)/2, and centered clearance (C) is given by the following formula: C=(Dgmax+Dgmin)/2−Rr. The gearbox of any preceding clause, wherein the gutter includes a gutter center. The gutter center is offset from the rotational axis of the rotor in the radial direction of the rotor. The gearbox of any preceding clause, wherein the rotor has a radius (Rr). The gutter has a radius (Rg). The gutter center is offset in the radial direction of the rotor by an eccentricity distance (e) to have an eccentricity ratio (ε) from two thousandths to seventy-six hundredths. The eccentricity ratio (ε) is the ratio of an eccentricity distance (e) to the difference between the gutter radius and the rotor radius (Rg−Rr). The gearbox of any preceding clause, wherein the gutter includes a scavenge port. The gutter center is offset from the rotation axis of the rotor by an eccentricity angle that is between two hundred seventy degrees and three hundred sixty degrees. The eccentricity angle is an angular position in the rotation direction of the rotor from a reference location. The reference location is the center of a scavenge port. The gearbox of any preceding clause, further including an epicyclical gear train. The epicyclical gear train includes a sun gear, a plurality of planet gears, and a ring gear. The sun gear is configured to receive a torque and rotate about an axis of rotation. Each planet gear of the plurality of planet gears engages with the sun gear to be rotated by the sun gear. The ring gear engages with each planet gear of the plurality of planet gears. The gearbox of any preceding clause, wherein the gutter is located radially outward of the ring gear in the rotational direction of the rotor. The gearbox of any preceding clause, wherein the gutter is integrally formed with the ring gear. The gearbox of any preceding clause, wherein the ring gear engages with each planet gear of the plurality of planet gears to rotate about the rotational axis of the sun gear. The ring gear is the rotor and the rotational axis of the rotor is the rotational axis of the sun gear. The gearbox of any preceding clause, wherein the plurality of planet gears are collectively rotatable about the rotational axis of the sun gear. The plurality of planet gears is the rotor, and the rotational axis of the rotor is the rotational axis of the sun gear. The gearbox of any preceding clause, further including a carrier. The planet gears are rotatably connected to the carrier. The carrier rotates about the rotation axis of the sun gear as the plurality of planet gears collectively rotate. The gearbox of any preceding clause, wherein each planet gear meshes with the sun gear at a nip formed between the sun gear and a corresponding planet gear. The oil system includes at least one oil nozzle configured to inject oil into one of the nips formed between the sun gear and the corresponding planet gear. The gearbox of any preceding clause, wherein the at least one oil nozzle is located upstream of the nip and injects oil in a direction toward the nip. The gearbox of any preceding clause, wherein each planet gear meshes with the ring gear at a nip formed between the ring gear and a corresponding planet gear. The oil system includes at least one oil nozzle configured to inject oil into one of the nips formed between the ring gear and the corresponding planet gear. The gearbox of any preceding clause, wherein the at least one oil nozzle is located upstream of the nip and injects oil in a direction toward the nip. A gas turbine engine including a core, an output element, and the gearbox of any preceding clause. The core includes a compression section, a combustion section, and a turbine section. The gearbox is coupled to the core to transmit torque and power from the core to the output element. The gas turbine engine of the preceding clause, further including a fan. The fan includes a fan rotor and a plurality of fan blades extending radially outward from the fan rotor. The fan rotor is the output element. The gas turbine engine of any preceding clause, further including a propeller assembly. The propeller assembly includes a propeller shaft and a plurality of propeller blades extending outwardly from the propeller shaft. The propeller shaft is the output element. A gearbox for a gas turbine engine. The gearbox includes a rotor, an outer casing, and a gutter. The rotor is rotatable about a rotational axis in a rotational direction. The rotor has a radial direction and expels oil radially outward when the rotor rotates. The outer casing is positioned radially outward of the rotor. The gutter is positioned radially outward of the rotor in the radial direction of the rotor between the outer casing and the rotor. The gutter also is positioned to collect oil expelled by the rotor when the rotor rotates. The gutter includes a plurality of gutter openings around a circumference of the gutter. Each gutter opening of the plurality of gutter openings allows oil to flow out of the gutter and into a cavity formed between the gutter and the outer casing. The rotor is positioned eccentrically with respect to at least one of the outer casing and the gutter. A method of collecting oil from a rotating part. The method includes supplying oil to a rotor, rotating the rotor about a rotational axis in a rotational direction and expelling oil radially outward, and collecting the oil expelled by the rotor in a gutter. The gutter is positioned radially outward of the rotor in the radial direction of the rotor, and a radial distance from the rotational axis of the rotor to the gutter is variable in the rotational direction. The method of the preceding clause, wherein the gutter is positioned eccentrically with respect to the rotor. The method of any preceding clause, wherein the gutter has (i) a maximum distance from the rotational axis to the gutter (Dgmax), (ii) a minimum distance from the rotational axis to the gutter (Dg min), and (iii) an eccentricity ratio (ε) from two thousandths to seventy-six hundredths, the eccentricity ratio (ε) being the ratio of an eccentricity distance (e) to a centered clearance (C), wherein the eccentricity distance (e) is given by the following formula: e=(Dgmax−Dgmin)/2, and centered clearance (C) is given by the following formula: C=(Dgmax+Dgmin)/2−Rr. The method of any preceding clause, wherein the gutter includes a gutter center. The gutter center is offset from the rotational axis of the rotor in the radial direction of the rotor. The method of any preceding clause, wherein the rotor has a radius (Rr), the gutter has a radius (Rg), and the gutter center is offset in the radial direction of the rotor by an eccentricity distance (e) to have an eccentricity ratio (ε) from two thousandths to seventy-six hundredths, the eccentricity ratio (ε) being the ratio of an eccentricity distance (e) to the difference between the gutter radius and the rotor radius (Rg−Rr). The method of any preceding clause, wherein the gutter includes a scavenge port. The gutter center is offset from the rotation axis of the rotor by an eccentricity angle that is between two hundred seventy degrees and three hundred sixty degrees. The eccentricity angle is an angular position in the rotation direction of the rotor from a reference location. The reference location being a center of a scavenge port. The method of any preceding clause, wherein the rotor is part of an epicyclical gear train. The method further includes rotating a sun gear about a rotational axis to rotate the rotor. The method of any preceding clause, wherein the rotor is a ring gear connected to the sun gear by a plurality of planet gears. Each planet gear of the plurality of planet gears engages with the sun gear to be rotated by the sun gear, and the ring gear engages with each planet gear of the plurality of planet gears to rotate about the rotational axis of the sun gear. The method of any preceding clause, wherein the rotor is a plurality of planet gears collectively rotating about the rotational axis of the sun gear. Each planet gear of the plurality of planet gears engages with the sun gear to be rotated by the sun gear and engages with a ring gear. The method of any preceding clause, wherein the gutter is integrally formed with the ring gear. The method of any preceding clause, wherein each planet gear meshes with the sun gear at a nip formed between the sun gear and a corresponding planet gear. The method further includes injecting oil into at least one of the nips formed between the sun gear and the corresponding planet gear. The method of any preceding clause, wherein each planet gear meshes with the ring gear at a nip formed between the ring gear and a corresponding planet gear. The method further includes injecting oil into at least one of the nips formed between the ring gear and the corresponding planet gear. The method of any preceding clause, wherein the oil is injected upstream of the nip. Although the foregoing description is directed to the preferred embodiments, it is noted that other variations and modifications will be apparent to those skilled in the art, and may be made without departing from the spirit or scope of the disclosure Moreover, features described in connection with one embodiment may be used in conjunction with other embodiments, even if not explicitly stated above. | 35,671 |
11859547 | DETAILED DESCRIPTION Aspects of the disclosure herein are directed to a turbine engine including a multi-stage compressor section and a turbine section in axial flow arrangement. The multi-stage compressor section can include at least two rotating blades axially adjacent to a corresponding stationary vane. A stationary vane and an axially adjacent, downstream rotating blade can together define a stage. As such, the term “multi-stage compressor section”, as used herein, can refer to a compressor section including two or more stages. A drive shaft can rotational couple the turbine section to the multi-stage compressor section. The drive shaft can rotate about an axis. A thrust bearing can be provided radially between the drive shaft and a portion of the multi-stage compressor section, with respect to the axis. The balance cavity can be fluidly coupled to a downstream portion of the multi-stage compressor section and include a fluid from the downstream portion. During operation of the turbine engine, the turbine engine can rotate the drive shaft, which can rotate the multi-stage compressor section. The overall thrust of the turbine ending can exert fore-to-aft axial force on the drive shaft with respect to the axis, which is ultimately transferred to the thrust bearing. The balance cavity can exert an aft-to-fore axial force, with respect to the axis, on the thrust bearing. The aft-to-fore force exerted by the balancing cavity can oppose and counteract the fore-to-aft force on the thrust bearing. The balance cavity, as described herein, can counteract or balance an axial force on a thrust bearing that rotationally supports a portion of the drive shaft that is axially forward the turbine section. Under some operating conditions, the turbine engine can experience relatively high axial loads. The balance cavity, as described herein, is used to ensure that the thrust bearing can continue to rotationally support the drive shaft, without failing, under all operating conditions of the turbine engine. For purposes of illustration, the present disclosure will be described with respect to a balance cavity provided within the turbine engine, with the balance cavity being provided near a portion of the multi-stage compressor section. It will be understood, however, that aspects of the disclosure described herein are not so limited and can have general applicability within other engines. For example, the disclosure can have applicability for a balance cavity in other engines or vehicles, and can be used to provide benefits in industrial, commercial, and residential applications. As used herein, the term “upstream” refers to a direction that is opposite the fluid flow direction, and the term “downstream” refers to a direction that is in the same direction as the fluid flow. The term “fore” or “forward” means in front of something and “aft” or “rearward” means behind something. For example, when used in terms of fluid flow, fore/forward can mean upstream and aft/rearward can mean downstream. Additionally, as used herein, the terms “radial” or “radially” refer to a direction away from a common center. For example, in the overall context of a turbine engine, radial refers to a direction along a ray extending between a center longitudinal axis of the engine and an outer engine circumference. Furthermore, as used herein, the term “set” or a “set” of elements can be any number of elements, including only one. Further yet, as used herein, the term “fluid” or iterations thereof can refer to any suitable fluid within the gas turbine engine at least a portion of the gas turbine engine is exposed to such as, but not limited to, combustion gases, ambient air, pressurized airflow, working airflow, or any combination thereof. It is yet further contemplated that the gas turbine engine can be other suitable turbine engine such as, but not limited to, a steam turbine engine or a supercritical carbon dioxide turbine engine. As a non-limiting example, the term “fluid” can refer to steam in a steam turbine engine, or to carbon dioxide in a supercritical carbon dioxide turbine engine. All directional references (e.g., radial, axial, proximal, distal, upper, lower, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, upstream, downstream, forward, aft, etc.) are only used for identification purposes to aid the reader's understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of aspects of the disclosure described herein. Connection references (e.g., attached, coupled, secured, fastened, connected, and joined) are to be construed broadly and can include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to one another. The exemplary drawings are for purposes of illustration only and the dimensions, positions, order and relative sizes reflected in the drawings attached hereto can vary. FIG.1is a schematic cross-sectional diagram of a turbine engine10for an aircraft. The turbine engine10has a generally longitudinally extending axis or engine centerline12extending forward14to aft16. The turbine engine10includes, in downstream serial flow relationship, a fan section18including a fan20, a compressor section22including a booster or low pressure (LP) compressor24and a high pressure (HP) compressor26, a combustion section28including a combustor30, a turbine section32including a HP turbine34, and a LP turbine36, and an exhaust section38. The fan section18includes a fan casing40surrounding the fan20. The fan20includes a plurality of fan blades42disposed radially about the engine centerline12. The HP compressor26, the combustor30, and the HP turbine34form an engine core44of the turbine engine10, which generates combustion gases. The engine core44is surrounded by core casing46, which can be coupled with the fan casing40. A drive shaft51can rotationally couple the compressor section22and the fan section18can be operatively coupled to the turbine section32. The rotation of the turbine section32can transfer a rotational force to the drive shaft51, which can in turn be transferred to at least one of the compressor section22or the fan section18to drive the compressor section22or fan section18. The drive shaft51can rotate about an axis. In the illustrated turbine engine10, the drive shaft51can rotate about the engine centerline12. The drive shaft51can include separate spools. As a non-limiting example, the drive shaft51can include an HP shaft or spool48disposed coaxially about the engine centerline12of the turbine engine10drivingly connects the HP turbine34to the HP compressor26. As a non-limiting example, the drive shaft51can include an LP shaft or spool50, which is disposed coaxially about the engine centerline12of the turbine engine10within the larger diameter annular HP spool48, drivingly connects the LP turbine36to the LP compressor24and fan20. The spools48,50can together define the drive shaft51. The spools48,50are rotatable about the engine centerline12and coupled to a plurality of rotatable elements, which can collectively define a rotor. The LP compressor24and the HP compressor26respectively include a plurality of compressor stages52,54, in which a set of compressor blades56,58rotate relative to a corresponding set of static compressor vanes60,62(also called a nozzle) to compress or pressurize the stream of fluid passing through the stage. In a single compressor stage52,54, multiple compressor blades56,58can be provided in a ring and can extend radially outwardly relative to the engine centerline12, from a blade platform to a blade tip, while the corresponding static compressor vanes60,62are positioned upstream of and adjacent to the rotating blades56,58. It is noted that the number of blades, vanes, and compressor stages shown inFIG.1were selected for illustrative purposes only, and that other numbers are possible. The blades56,58for a stage of the compressor can be mounted to a disk61, which is mounted to the corresponding one of the HP and LP spools48,50, with each stage having its own disk61. The vanes60,62for a stage of the compressor can be mounted to the core casing46in a circumferential arrangement. The HP turbine34and the LP turbine36respectively include a plurality of turbine stages64,66, in which a set of turbine blades68,70are rotated relative to a corresponding set of static turbine vanes72,74(also called a nozzle) to extract energy from the stream of fluid passing through the stage. In a single turbine stage64,66, multiple turbine blades68,70can be provided in a ring and can extend radially outwardly relative to the engine centerline12, from a blade platform to a blade tip, while the corresponding static turbine vanes72,74are positioned upstream of and adjacent to the rotating turbine blades68,70. It is noted that the number of blades, vanes, and turbine stages shown inFIG.1were selected for illustrative purposes only, and that other numbers are possible. The turbine blades68,70for a stage of the turbine can be mounted to a disk71, which is mounted to the corresponding one of the HP and LP spools48,50, with each stage having a dedicated disk71. The vanes72,74for a stage of the compressor can be mounted to the core casing46in a circumferential arrangement. Complimentary to the rotor portion, the stationary portions of the turbine engine10, such as the static vanes60,62,72,74among the compressor and turbine sections22,32are also referred to individually or collectively as a stator63. As such, the stator63can refer to the combination of non-rotating elements throughout the turbine engine10. A set of thrust bearings can rotationally support the drive shaft51. As a non-limiting example, the set of thrust bearings can include, at least, a forward thrust bearing90and an aft thrust bearing92. The forward thrust bearing90can be located axially forward, with respect to the engine centerline12, from the aft thrust bearing92. The forward thrust bearing90can be provided radially between the drive shaft51and the compressor section22, with respect to the engine centerline12. The aft thrust bearing92can be provided radially between the drive shaft51and the turbine section32, with respect to the engine centerline12. The turbine engine10can include a turbine balance cavity96along a portion of the turbine engine10confronting the aft thrust bearing92. In operation, the airflow exiting the fan section18is split such that a portion of the airflow is channeled into the LP compressor24, which then supplies pressurized airflow76to the HP compressor26, which further pressurizes the air. The pressurized airflow76from the HP compressor26is mixed with fuel in the combustor30and ignited, thereby generating combustion gases. Some work is extracted from these gases by the HP turbine34, which drives the HP compressor26via the drive shaft51. The combustion gases are discharged into the LP turbine36, which extracts additional work to drive the LP compressor24, and the exhaust gas is ultimately discharged from the turbine engine10via the exhaust section38. The driving of the LP turbine36drives the LP spool50to rotate the fan20and the LP compressor24. A portion of the pressurized airflow76can be drawn from the compressor section22as bleed air77. The bleed air77can be drawn from the pressurized airflow76and provided to engine components requiring cooling. The temperature of pressurized airflow76entering the combustor30is significantly increased. As such, cooling provided by the bleed air77is necessary for operating of such engine components in the heightened temperature environments. A remaining portion of the airflow exiting the fan section, a bypass airflow78bypasses the LP compressor24and engine core44and exits the turbine engine10through a stationary vane row, and more particularly an outlet guide vane assembly80, comprising a plurality of airfoil guide vanes82, at the fan exhaust side84. More specifically, a circumferential row of radially extending airfoil guide vanes82are utilized adjacent the fan section18to exert some directional control of the bypass airflow78. Some of the air supplied by the fan20can bypass the engine core44and be used for cooling of portions, especially hot portions, of the turbine engine10, and/or used to cool or power other aspects of the aircraft. In the context of a turbine engine, the hot portions of the engine are normally downstream of the combustor30, especially the turbine section32, with the HP turbine34being the hottest portion as it is directly downstream of the combustion section28. Other sources of cooling fluid can be, but are not limited to, fluid discharged from the LP compressor24or the HP compressor26. FIG.2is a schematic cross-sectional view of a multi-stage compressor section100suitable for use as the compressor section22of the turbine engine10ofFIG.1. The multi-stage compressor section100can be rotationally coupled to a drive shaft102, which can be rotationally coupled to a turbine section (e.g., the turbine section32) downstream of the multi-stage compressor section100. The drive shaft102can rotate about an axis104. A thrust bearing106can rotationally support the drive shaft102and be located between a portion of the drive shaft102and a portion of the multi-stage compressor section100. As a non-limiting example, the thrust bearing106can be located between a portion of the drive shaft102and a static portion of the multi-stage compressor section100. A balance cavity108can be located at least partially axially fore of the thrust bearing106, with respect to the axis104. The balance cavity108can be fluidly coupled to a pressurized fluid from a portion of the multi-stage compressor section100. The balance cavity108can be operably coupled to the thrust bearing106(e.g., a wall of the balance cavity108can be operably coupled to the thrust bearing106). During operation of the turbine engine a thrust can be generated, which in turn exerts a fore-to-aft axial force on the drive shaft102. The fore-to-aft axial force can ultimately be transferred to the thrust bearing106to define a first axial force110. The balance cavity108can exert an aft-to-fore axial force on the thrust bearing106, with respect to the axis104. As a non-limiting example, the balance cavity108can exert a second axial force112on the thrust bearing106that counteracts, opposes, or otherwise balances the first axial force110. It is contemplated that the first axial force110can be larger than the second axial force112such that the balance cavity108only reduces an overall axial force experienced across the thrust bearing. Alternatively, the first axial force110can be equal, but opposite in magnitude, to the second axial force112such that the thrust bearing is held in axial equilibrium. The thrust bearing106can be provided between a portion of the drive shaft102and a corresponding portion of the multi-stage compressor section100. As a non-limiting example, the thrust bearing106can be provided between a portion of the drive shaft102and a stationary component101of the multi-stage compressor section100. The thrust bearing106can extend radially between the drive shaft102and at least a portion of the multi-stage compressor section100. The thrust bearing106can be any suitable bearing such as, but not limited to, a roller bearing, a ball bearing, a double ball bearing, a tapered roller bearing, a foil/gas bearing, a journal bearing, a spherical bearing, or any combination thereof. The multi-stage compressor section100can include an LP compressor114and an HP compressor116provided axially downstream of the LP compressor114, with respect to the axis104. The LP compressor114, like the LP compressor24ofFIG.1, can include a set of stationary LP compressor vanes117and a set of rotating LP compressor blades118rotationally coupled to the drive shaft102. The HP compressor116, like the HP compressor26ofFIG.1, can include a set of stationary HP compressor vane120and a set of rotating HP compressor blades122rotationally coupled to the drive shaft102. Each rotating LP compressor blade118and rotating HP compressor blade122can be provided axially downstream of a corresponding stationary LP compressor vane117or stationary HP compressor vane120, respectively, with respect to the axis104, and define a corresponding stage of the multi-stage compressor section100. A booster section124can be defined by a downstream stage of the LP compressor114. As a non-limiting example, the booster section124can be the farthest axially downstream stage of the LP compressor114. The balance cavity108can include first pressurized fluid defining a first fluid160. The first fluid160can be dispersed throughout the balance cavity108as indicated by the dots throughout the balance cavity108. The balance cavity108can be located radially inwardly from at least a portion of the LP, with respect to the axis104. As a non-limiting example, the balance cavity108can be located radially inwardly from the booster section124, with respect to the axis104. The balance cavity108can be provided within any portion of the multi-stage compressor section100axially forward the combustion section. Further, the thrust bearing106can be provided along any suitable portion of the multi-stage compressor section100along the drive shaft102(e.g., along the HP spool48or the LP spool50ofFIG.1). As such, the balance cavity108can be at least partially located along the any portion of the drive shaft102. The balance cavity108, as illustrated, is a single balance cavity108. However, it will be appreciated that the balance cavity108can be included within a plurality of balance cavities108that are fluidly coupled to one another. As a non-limiting example, the balance cavity108can be one balance cavity108set of a plurality of balance cavities108that are radially, axially, or circumferentially spaced from each other, with respect to the axis104. A fan section126can be provided upstream of the multi-stage compressor section100. The fan section126, like the fan section18ofFIG.1, can include at least one rotating fan blade128. The at least one rotating fan blade128can be rotationally coupled to the drive shaft102. As a non-limiting example, the at least one rotating fan blade128can be selectively rotationally coupled to the drive shaft102such that the fan section126can be selectively coupled or decoupled to the drive shaft102. The balance cavity108can be fluidly coupled to the multi-stage compressor section100. As a non-limiting example, the balance cavity108can be fluidly coupled to the HP compressor116. A balance cavity inlet line130can fluidly couple the HP compressor116to the balance cavity108. As a non-limiting example, the balance cavity inlet line130can be fluidly coupled along or between the first and fourth stage of the HP compressor116. As a non-limiting example, the balance cavity inlet line130can be fluidly coupled to the 1.5 stage of the HP compressor116(e.g., between the rotating HP compressor blade122and the stationary HP compressor vane120of the second stage of the HP compressor116). The balance cavity inlet line130is shown to be fluidly coupled to a radially outer portion of the HP compressor116, with respect to the axis104. However, as illustrated by the balance cavity inlet line130in phantom lines, the balance cavity inlet line130can also or alternatively fluidly coupled to a radially inner portion of the HP compressor116, with respect to the axis104. The balance cavity inlet line130, as described herein, can be one of either of the two balance cavity inlet lines130described herein. Alternatively, the balance cavity inlet line130can be both of the balance cavity inlet lines130fluidly coupled to the radially outer portion of the HP compressor116and the radially inner portion of the HP compressor116, with respect to the axis104. The balance cavity inlet line130can include at least one component configured to affect a characteristic of a fluid (e.g., the pressurized air from the HP compressor116) flowing through the balance cavity inlet line130and into the balance cavity108. As a non-limiting example, the balance cavity inlet line130can include a heat exchanger132. The heat exchanger132can be fluidly coupled to a coolant (e.g., an ambient airflow, refrigerant, etc.) that has a lower temperature than the fluid within the balance cavity inlet line130that flows into the heat exchanger132. The heat exchanger132can effectively cool the fluid by transferring the heat from the fluid and into the coolant. As a non-limiting example, the balance cavity inlet line130can include a particle separator134configured to remove or otherwise filter out one or more particles from the fluid flowing into the particle separator134. A recoup cavity136can be fluidly coupled to the balance cavity108. The recoup cavity136can include a second pressurized fluid (e.g., the pressurized air or the first pressurized fluid from the balance cavity108) defining the second fluid162. The second fluid162can be dispersed throughout the recoup cavity136as designated by the dots within the recoup cavity136. The recoup cavity136is configured to capture or otherwise recoup a pressurized fluid from the balance cavity108and transfer the pressurized fluid to other portions of the turbine engine. It will be appreciated, however, that the recoup cavity136can be integrally formed with the balance cavity108such that the balance cavity108can transfer at least a portion of the pressurized fluid within the balance cavity108to another portion of the turbine engine10. The recoup cavity136can be located at least partially radially outwardly from the balance cavity108, with respect to the axis104. The recoup cavity136can be located radially inwardly from the booster section124with respect to the axis104. A seal138can be provided between the recoup cavity136and the balance cavity108and define the fluid coupling between the recoup cavity136and the balance cavity108. As a non-limiting example, the seal138can be a piston seal. It will be appreciated, however, that the seal138can be any other suitable seal such as, but not limited to, a labyrinth seal, a brush seal, a non-contact seal, or any combination thereof. The recoup cavity136can be fluidly coupled to an exhaust line140. As illustrated, the exhaust line140can include two branches. One of the two branches is fluidly coupled to a diverter valve142. The other of the two branches is fluidly coupled to a portion of the multi-stage compressor section100downstream of the LP compressor114. As a non-limiting example, the exhaust line140can be fluidly coupled to a portion of the multi-stage compressor section100downstream of the LP compressor114and upstream of the HP compressor116. The diverter valve142can selectively fluidly couple the exhaust line140to at least one of a turbine line144or a bypass line146. As a non-limiting example, the turbine line144can be fluidly coupled to at least one of the turbine section, or the exhaust section (e.g., the exhaust section38ofFIG.1). The bypass line146can be fluidly coupled to a portion of the turbine engine that is directed away from or otherwise bypasses the combustion section of the turbine engine. As a non-limiting example, the turbine engine can include a secondary flow path148that the bypass line146is fluidly coupled to. The secondary flow path148can be fluidly coupled to or otherwise form a portion of at least one of a thrust reverser, a downstream portion of the turbine engine (e.g., the turbine section or exhaust section) or otherwise be fluidly coupled to an exterior portion of the turbine engine. The seal138can be provided a first radial distance between the axis104and a radially inward portion of the seal138. The booster section124can be provided a second radial distance between the axis104and a radially inward portion of the booster section124. The first distance can be smaller than the second distance. The balance cavity108, the recoup cavity136, and the seal138can extend circumferentially about the axis104. In other words, the balance cavity108, the recoup cavity136, and the seal138can define continuous annular components of the turbine engine. Alternatively, at least one of the balance cavity108, the recoup cavity136, or the seal138can be segmented (e.g., they are one of a plurality of balance cavities108, recoup cavities136, or seal138, respectively) or not extend across an entire circumference of the axis104. The turbine engine can include additional balance cavities. As a non-limiting example, the turbine engine can include the turbine balance cavity96(FIG.1) within the turbine section that is configured to apply an opposing axial force on the turbine thrust bearing92(FIG.1) that rotationally supports an aft portion of the drive shaft102. In other words, the turbine engine, as described herein, can include the balance cavity108in conjunction with an additional balance cavity such as those described in the prior art. During operation of the turbine engine, the turbine section can apply a rotational force to the drive shaft102, which can in turn rotate at least a portion of multi-stage compressor section100and selectively rotate at least a portion of the fan section126. As the fan section126rotates, an inlet airflow150can be drawn into the turbine engine. The inlet airflow150can be defined by an ambient airflow surrounding the turbine engine. A remaining portion of the ambient airflow that is not drawn in by the fan section126can flow around the turbine engine as an exterior airflow152, which can ultimately merge with an exhaust fluid downstream of the exhaust section. The exhaust fluid and the exterior airflow152can, together, define an overall thrust of the turbine engine. Once past the fan section126, the inlet airflow150can branch in at least two directions. A first portion of the inlet airflow150can branch into the multi-stage compressor section100to define a primary airflow154within a main flow path extending through the multi-stage compressor section100, the turbine section, and ultimately out the exhaust section. A second portion can flow into the secondary flow path148and define a secondary airflow156. As a non-limiting example, the secondary airflow156can be fluidly coupled to a thrust reverser where it can exit the turbine engine in a direction opposing the exterior airflow152. As a non-limiting example, the secondary airflow156can be fluidly coupled to a downstream portion of the turbine engine (e.g., the turbine section, combustion section, or exhaust section), where it can cool various components within the downstream portion of the turbine engine. As a non-limiting example, the secondary airflow156can be fluidly coupled to the exterior airflow152and merge with the exterior airflow152such that the secondary airflow156can be used to generate at least a portion of the overall thrust of the turbine engine. As the primary airflow154flows through the LP compressor114, the primary airflow154can be compressed or otherwise pressurized and define a compressed primary airflow158. The compressed primary airflow158can flow into the HP compressor116where it is compressed or otherwise pressurized further. The primary airflow154can be defined by a first pressure while the compressed primary airflow158can be defined by a second pressure, larger than the first pressure. It will be appreciated that the first pressure and the second pressure can vary along the stages of the respective LP compressor114and HP compressor116, respectively. The balance cavity108can be fluidly coupled to the compressed primary airflow158through the balance cavity inlet line130to define the first fluid160within the balance cavity108. Before flowing into the balance cavity108, however, the compressed primary airflow158within the balance cavity inlet line130can be heated, via the heat exchanger132, or filtered, via the particle separator134. The first fluid160can be defined by the second pressure. At least a portion of the first fluid160within the balance cavity108can flow into the recoup cavity136to define the second fluid162at a third pressure, smaller than the second pressure. It is contemplated that the seal138can be biased between a high pressure region and a low pressure region such that fluid only flows from the high pressure region and to the low pressure region. In other words, the seal138can be biased such that fluid only flows from the balance cavity108and into the recoup cavity136as the first fluid160is at a higher pressure than the second fluid162. The second fluid162can be exhausted directly into the booster section124from the recoup cavity136. As such, the second fluid162can be exhausted form the recoup cavity136to the booster section and exhausted via the exhaust line140where the second fluid162can be exhausted back into the multi stage compressor100(e.g., downstream of the LP compressor114and upstream of the HP compressor116), or selectively exhausted into at least one of the secondary flow path148via the bypass line146, or to downstream of or within the turbine section via the turbine line144. The overall thrust of the turbine engine can exert the fore-to-aft axial force on the drive shaft102, which can ultimately be at least partially transferred to the thrust bearing as the first axial force110. The pressure of the second fluid162can be sufficient to exert the second axial force112on the thrust bearing that partially counteracts (e.g., is equal but opposite in magnitude) the first axial force110. As such, the overall axial force experienced across the thrust bearing106can be reduced. It is further contemplated that at least a portion of the compressed primary airflow158can be fluidly coupled to a turbine balance cavity inlet line164, which can be provided in the turbine section of the turbine engine and be used to balance or offset an axial force exerted on a thrust bearing in the turbine section from the drive shaft102. It is contemplated that during normal operation of the turbine engine, the fan section126can be decoupled or at least partially decoupled from the drive shaft102to ensure that the fan section126is operating at an optimal rotational velocity. At least a portion of the fore-to-aft axial force generated by the overall thrust of the turbine engine can be transferred to or through the fan section126when the fan section126is coupled to the drive shaft102. However, when decoupled, a larger fore-to-aft axial force is experienced across the thrust bearing106as a portion of the fore-to-aft axial force it is no longer being applied to the fan section126. This, in turn, increases the overall first axial force110that is being exerted on the thrust bearing106. It is contemplated that the second axial force112, created by the balance cavity108, can be sufficient to at least partially counteract the first axial force110under all operating conditions, including when the fan section126is at least partially decoupled from the drive shaft102. Benefits of the present disclosure include a thrust bearing in the compressor section with a longer time-on-wing than a conventional thrust bearing in a conventional compressor section. As used herein, the term “time-on-wing” or “wing-time” can refer to the total amount of time or use that a specific component can have before it must be removed from the turbine engine and replaced, or otherwise repaired. For example, the conventional compressor section does not include a balance cavity. As such, the conventional thrust bearing in the conventional compressor section will experience unchecked (e.g., unopposed) axial loading through the rotational forces of the drive shaft, which over time will wear down the conventional thrust bearing. The turbine engine as described herein, however, includes a thrust bearing that is positioned proximate the balance cavity, which can counteract or otherwise reduce, through an opposing axial force, the axial force on the thrust bearing from the drive shaft. It is contemplated that the use of the balance cavity can reduce the overall axial force experienced along the thrust bearing by 10-35% when compared to conventional thrust bearings in a conventional compressor section. This ultimately increases the overall time-on-wing of the thrust bearing with respect to the time-on-wing of the conventional thrust bearing. Further benefits include a thrust bearing configured to operate under a wider range of operational conditions of the turbine engine when compared to conventional thrust bearings in the conventional compressor section. As described above, the conventional compressor section does not include the balance cavity. As such, the overall axial force experienced across the conventional thrust bearing will be higher than the overall axial force experienced across the thrust bearing, as described herein, during all operational conditions. This, in turn, means that if the thrust bearing and the conventional thrust bearing were identical, the conventional thrust bearing would experience a larger overall axial force when under high-load conditions (e.g., the decoupling of the fan section) when compared to the thrust bearing as described herein. One way to help ensure that the conventional thrust bearing does not fail, would be to increase the size or material properties of the conventional thrust bearing, thus increasing the overall cost and footprint of the conventional thrust bearing. The thrust bearing, as described herein, can withstand operational conditions of the turbine engine without having to increase the size or material properties of the thrust bearing. Further yet, the counteraction of the axial forces across the thrust bearing from the drive shaft can allow for increased operation of the turbine engine when compared to a conventional turbine engine including the conventional thrust bearing. It is contemplated that the rotational forces of the drive shaft can be increased as the rotational velocity of the drive shaft increases. The higher the rotational velocity of the drive shaft, the fast the compressor section rotates, which in turn further comprises or pressures the primary airflow. This ultimately increases the overall efficiency or power output of the turbine engine. In other words, this increases the overall thrust of the turbine engine. One drawback, however, of increasing the overall thrust is that the axial force exerted on the thrust bearing is higher. The balance cavity, as described herein, however, can be utilized to at least partially oppose the increased axial load. The at least partial opposition to increased axial loads helps ensure that the turbine engine can operate under conditions where the drive shaft has a relatively high rotational velocity. Further yet, as the pressure of the primary airflow in the compressor section increases, the pressure of the fluid within the balance cavity increases. This means that the axial force exerted on the thrust bearing by the balance cavity also increases. As such, the axial force exerted on the thrust bearing by the balance cavity can at least partially scale with the operational condition of the turbine engine. This ultimately results in a turbine engine with increased power output when compared to the conventional turbine engine. Further benefits of the present disclosure include a more efficient balance cavity when compared to a conventional balance cavity for a conventional turbine engine. For example, the conventional balance cavity (e.g., one provided within the turbine section) can draw fluid from the compressor section or turbine section to generate the needed axial force. This can result in a 1% to 2% fuel burn penalty of the conventional turbine engine. In other words, the inclusion of the conventional balance cavity can reduce the fuel efficiency of the turbine engine by 1% to 2% compared to a conventional turbine engine without the conventional balance cavity. The balance cavity, as described herein, however, draws a fluid from the compressor section and recirculates (e.g., through the recoup cavity) at least a portion of it back through the turbine engine to be used to generate thrust or cool components of the turbine engine. This, in turn, increased the efficiency of the balance cavity with respect to the conventional balance cavity. The balance cavity, as described herein, can result in a 0.06% to 0.12% fuel burn penalty of the turbine engine. Further benefits of the present disclosure include a balance cavity provided within the compressor section. Conventional turbine engines do not include a compressor balance cavity for various reasons. First, if a conventional turbine engine were to include a conventional balance cavity (e.g., one found in the turbine section) in the compressor section, then materials of the compressor would have to be upgraded. This is due to the fact that in order for the balance cavity to function, the balance cavity must draw in air from a relatively high-temperature area and transfer it into the balance cavity, which is provided within a relatively low-temperature area with respect to the high-temperature area. The low-temperature area is not rated (e.g., able to withstand) the air from the high-temperature area. As such, the conventional turbine engine would need to increase material properties of the low-temperature area to better withstand the high-temperature. The balance cavity, as described herein, however, can include one or more cooling elements (e.g., the heat exchanger) provided along the balance cavity inlet line. This lowers the temperature of the air that is provided to the balance cavity, thus eliminating the need to change the materials of the compressor section to withstand the relatively high-temperature air. Second, if a conventional turbine engine were to include a conventional balance cavity (e.g., one found in the turbine section) in the compressor section, the air from the balance cavity would not be able to be exhausted without an adverse effect to the turbine engine. For example, the conventional turbine balance cavity is provided near the exhaust section or the LP turbine. As such, the conventional turbine balance cavity can exhaust the fluid within the conventional turbine balance cavity into the LP turbine or the exhaust section without adverse effects. If this same arrangement were to be put in the compressor section (e.g., the balance cavity would directly exhaust to the LP compressor), the efficiency of the compressor section would be adversely affected. The balance cavity, as described herein, however, exhausts to the recoup cavity, which selectively exhausts the fluid within the recoup cavity to locations (e.g., the bypass line, the turbine line, the HP compressor, etc.) that are able to accept the fluid from the balance cavity without adverse effects. Further yet, the inclusion of the balance cavity provided within the compressor section provides additional benefits. First, the construction of the turbine engine yields additional space at within the compressor section that can be used to package the balance cavity. This space, in the conventional turbine engine, is unused. Second, a conventional balance cavity provided within the turbine section requires two seals (one seal provided along the outer diameter and one seal provided along the inner diameter) in order to properly function. The balance cavity, as described herein, however, only requires a single seal provided along the outer diameter of the balance cavity. This, in turn, results in a reduced weight, additional available space, and lower leakage losses with respect to the conventional balance cavity. To the extent not already described, the different features and structures of the various aspects can be used in combination, or in substitution with each other as desired. That one feature is not illustrated in all of the examples is not meant to be construed that it cannot be so illustrated but is done for brevity of description. Thus, the various features of the different aspects can be mixed and matched as desired to form new aspects, whether or not the new aspects are expressly described. All combinations or permutations of features described herein are covered by this disclosure. This written description uses examples to describe aspects of the disclosure described herein, including the best mode, and also to enable any person skilled in the art to practice aspects of the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of aspects of the disclosure is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. Further aspects are provided by the subject matter of the following clauses: A turbine engine comprising a drive shaft rotatable about an axis, a multi-stage compressor section circumscribing and driven by the drive shaft, a turbine section circumscribing and operably coupled to the drive shaft, a thrust bearing provided between the drive shaft and at least a portion of the multi-stage compressor section and rotationally supporting the drive shaft, and a balance cavity, located at least partially axially upstream of the thrust bearing, with respect to the axis, and fluidly coupled to at least one of the multi-stages of the multi-stage compressor section, wherein during operation of the turbine engine, a first axial force is applied to the thrust bearing in a fore-to-aft direction by the drive shaft, with respect to the axis, and a second axial force is applied by the balance cavity in an opposing direction to the first axial force. The turbine engine of any preceding clause, wherein the multi-stage compressor section further comprises a first portion having a first airflow at a first pressure, and a second portion, downstream of the first section, having a second airflow at a second pressure, higher than the first pressure, and wherein the balance cavity is fluidly coupled to the second portion such that at least a portion of the second airflow is supplied to the balance cavity. The turbine engine of any preceding clause, wherein the balance cavity is located radially inwardly from the first portion, with respect to the axis. The turbine engine of any preceding clause, wherein the first portion is a low pressure compressor and the second portion is a high pressure compressor. The turbine engine of any preceding clause, wherein the low pressure compressor comprises a booster section provided along a downstream portion multi-stage of the low pressure compressor, and wherein the balance cavity is located radially inwardly from the booster section, with respect to the axis. The turbine engine of any preceding clause, wherein the balance cavity is fluidly coupled to the high pressure compressor between a first stage and a fourth stage of the high pressure compressor. The turbine engine of any preceding clause, wherein the booster section is a farthest axially downstream stage of the low pressure compressor. The turbine engine of any preceding clause, further comprising a balance cavity inlet line fluidly coupling the balance cavity and either a radially inward portion or a radially outward portion of the second portion, with respect to the axis. The turbine engine of any preceding clause, further comprising a heat exchanger thermally coupled to the balance cavity inlet line, and configured to cool at least a portion of the second fluid before it enters the balance cavity, and a particle separator fluidly coupled to the balance cavity inlet line and configured to filter a fluid from the second portion before it enters the balance cavity. The turbine engine of any preceding clause, further comprising a recoup cavity fluidly coupled to the balance cavity. The turbine engine of any preceding clause, wherein the recoup cavity is provided radially outwardly from balance cavity, with respect to the axis. The turbine engine of any preceding clause, further comprising a main flow path having a primary airflow and extending through the multi-stage compressor section and the turbine section, and a secondary flow path having a secondary airflow and provided upstream of the multi-stage compressor section, wherein the recoup cavity is configured to exhaust a fluid from the recoup cavity to at least one of a booster section, downstream of or at a downstream portion of the turbine section, the secondary flow path, or to atmosphere. The turbine engine of any preceding clause, further comprising an exhaust line fluidly coupling the recoup cavity to at least one of the booster section, the turbine section, the secondary flow path, or atmosphere. The turbine engine of any preceding clause, wherein the exhaust line fluidly couples the recoup cavity to the booster section, the turbine section, and the atmosphere, and selectively fluidly coupled to the multi-stage compressor section or the secondary flow path. The turbine engine of any preceding clause, wherein the secondary flow path includes an airflow configured to cool a downstream portion of the turbine engine, provide a reverse thrust of the turbine engine, or contribute to a thrust of the turbine engine. The turbine engine of any preceding clause, further comprising a seal provided between the balance cavity and the recoup cavity. The turbine engine of any preceding clause, wherein the multi-stage compressor section further comprises a booster section, and wherein the seal is radially spaced from the booster section, with respect to the axis. The turbine engine of any preceding clause, wherein the booster section and the seal both extend circumferentially about an entirety of the axis, and wherein a first radius is defined between a radially innermost portion of the booster section and axis, and a second radius, smaller than the first radius, is defined between a radially innermost portion of the seal and the axis. The turbine engine of any preceding clause, further comprising a recoup cavity fluidly coupled to the balance cavity, wherein the balance cavity and the recoup cavity each extend circumferentially about an entirety of the axis. The turbine engine of any preceding clause, further comprising a turbine balance cavity located within the turbine section, wherein the turbine balance cavity is fluidly coupled to a portion of the multi-stage compressor section. A multi-stage compressor section comprising a drive shaft rotatable about an axis, a thrust bearing provided between the drive shaft and at least a portion of the multi-stage compressor section and rotationally supporting the drive shaft, and a balance cavity, located at least partially axially upstream of the thrust bearing, with respect to the axis, and fluidly coupled to at least one of the multi-stages of the multi-stage compressor section, wherein during operation of the multi-stage compressor section, a first axial force is applied to the thrust bearing in a fore-to-aft direction by the drive shaft, with respect to the axis, and a second axial force is applied by the balance cavity in an opposing direction to the first axial force. | 47,794 |
11859548 | DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a gas turbine and a control method thereof, and a combined cycle plant according to the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to this embodiment, and in a case in which there are a plurality of embodiments, the present invention also includes configurations in which the embodiments are combined with each other. First Embodiment FIG.1is a schematic configuration diagram illustrating a gas turbine of a first embodiment. In the first embodiment, as illustrated inFIG.1, a gas turbine10includes a compressor11, a combustor12, a turbine13, and a control device14. The compressor11and the turbine13are integrally rotatably coupled with a rotating shaft21, and a generator22is coupled to the rotating shaft21. The compressor11compresses air A flowing from an air intake line L1. The combustor12mixes and combusts compressed air CA supplied from the compressor11through a compressed air supply line L2and fuel F supplied from a fuel gas supply line L3. The turbine13is rotationally driven by combustion gas CG supplied from the combustor12through a combustion gas supply line L4. The generator22is driven by a rotational power transmitted by the rotation of the turbine13. In addition, a flue gas discharge line L5that discharges flue gas EG is coupled to the turbine13. Therefore, during the operation of the gas turbine10, the compressor11compresses the air A, and the combustor12mixes and combusts the supplied compressed air CA and the fuel F. The turbine13is rotationally driven by the combustion gas CG supplied from the combustor12, and the generator22generates electricity. The gas turbine10(turbine13) discharges the flue gas EG. In addition, the gas turbine10includes a first heat exchanger (for example, an intake air heater)31, a second heat exchanger32, a third heat exchanger33, a first flow rate adjusting valve (heat exchange amount adjusting device)34, and a second flow rate adjusting valve (heat exchange amount adjusting device)35. In the first embodiment, the first heat exchanger31and the second heat exchanger32correspond to the air temperature adjusting heat exchanger of the present invention, and the third heat exchanger33corresponds to the compressed air cooling heat exchanger. In the first embodiment, heat is indirectly exchanged between the air A to be taken into the compressor11and the compressed air CA generated by the compressor11through a first medium. The first heat exchanger31is provided in the air intake line L1. The first heat exchanger31exchanges heat between the air A taken from the air intake line L1and the first medium (for example, hot water) HW. That is, the air A flowing through the air intake line L1is heated with the first medium (for example, water) HW by the first heat exchanger31and then taken into the compressor11. A first cooling air supply line L11and a second cooling air supply line L12are provided in parallel between the compressor11and the turbine13. The first cooling air supply line L11and the second cooling air supply line L12supplies part of the compressed air CA compressed by the compressor11to the turbine13as cooling air. One end portion of the first cooling air supply line L11and one end portion of the second cooling air supply line L12are joined together and coupled to a combustor casing chamber (not illustrated) of the compressor11. The other end portions thereof are joined together and coupled to a high temperature portion of the turbine13. The second heat exchanger32is provided in the first cooling air supply line L11, and the third heat exchanger33is provided in the second cooling air supply line L12. In addition, a first flow rate adjusting valve34is provided on an upstream side of the second heat exchanger32in the first cooling air supply line L11. A second flow rate adjusting valve35is provided on an upstream side of the third heat exchanger33in the second cooling air supply line L12. A first medium circulation line L13is provided between the first heat exchanger31and the second heat exchanger32. A circulation pump41is provided in the first medium circulation line L13. Therefore, the circulation pump41can be driven to circulate the first medium HW between the first heat exchanger31and the second heat exchanger32through the first medium circulation line L13. Then, the first medium HW circulating through the first medium circulation line L13is heated with the compressed air CA1in the second heat exchanger32, which flows through the first cooling air supply line L11, to heat the air A in the first heat exchanger31, which flows through the air intake line L1. Here, the second heat exchanger32is, for example, a turbine cooling air (TCA) cooler. The compressed air CA1flowing through the first cooling air supply line L11is cooled in the second heat exchanger32with the first medium HW circulating through the first medium circulation line L13. The third heat exchanger33is provided in a second medium supply line L14. A supply pump42is provided in the second medium supply line L14. Here, the third heat exchanger33is, for example, a TCA cooler and may be a cooling tower. Therefore, the supply pump42is driven to cause a second medium (for example, air) A1to flow through the second medium supply line L14. Then, compressed air CA2flowing through the second cooling air supply line L12is cooled in the third heat exchanger33with the second medium A1flowing through the second medium supply line L14. The first flow rate adjusting valve34and the second flow rate adjusting valve35function as heat exchange amount adjusting devices that adjust the amount of heat of the compressed air CA1to be supplied to the second heat exchanger32. That is, the compressed air CA compressed by the compressor11is partially supplied through the first cooling air supply line L11and the second cooling air supply line L12to the turbine13as cooling air. In a case in which an opening degree of the first flow rate adjusting valve34is increased and an opening degree of the second flow rate adjusting valve35is decreased, a large amount of the compressed air CA flows to the first cooling air supply line L11side. Then, the amount of heat of the compressed air CA1in the first cooling air supply line L11increases, and the first medium HW circulating through the first medium circulation line L13is heated in the second heat exchanger32, so that the temperature is higher than before changing the opening degrees of the flow rate adjusting valves34and36. As a result, the air A in the air intake line L1is heated by the first heat exchanger31with the first medium HW that circulates through the first medium circulation line L13and has a high temperature, so that the temperature of the air A is higher than before changing the opening degrees. On the other hand, in a case in which the opening degree of the first flow rate adjusting valve34is decreased and the opening degree of the second flow rate adjusting valve35is increased, a large amount of the compressed air CA flows to the second cooling air supply line L12side. Then, the amount of heat of the compressed air CA1in the first cooling air supply line L11decreases, and the first medium HW circulating through the first medium circulation line L13is heated by the second heat exchanger32, but the temperature is lower than before chancing the opening degrees of the flow rate adjusting valves34and36. As a result, although the air A in the air intake line L1is heated in the first heat exchanger31with the first medium HW that circulates through the first medium circulation line L13and has a low temperature, the temperature of the air A is lower than before changing the opening degrees. The control device14controls the first flow rate adjusting valve34and the second flow rate adjusting valve35as the heat exchange amount adjusting devices based on the temperature of the air A to be taken into the compressor11. A first temperature sensor43is provided on a downstream side of the first heat exchanger31in the air intake line L1. The first temperature sensor43measures the temperature of the air A that flows through the air intake line L1and is heated in the first heat exchanger31, and outputs the measured temperature to the control device14. The control device14adjusts the opening degrees of the first flow rate adjusting valve34and the second flow rate adjusting valve35so that the temperature of the air A measured by the first temperature sensor43reaches a target temperature. In addition, the control device14controls the supply pump42based on a temperature of the compressed air CA (CA1+CA2) as cooling air to be supplied to the turbine13. A second temperature sensor44is provided in the joined line on a downstream side of the second heat exchanger32and the third heat exchanger33in the cooling air supply lines L11and L12. The second temperature sensor44measures the temperature of the compressed air CA (CA1+CA2) that flows through the cooling air supply lines L11and L12and is supplied to the turbine13, and outputs the measured temperature to the control device14. The control device14adjusts a rotation speed of the supply pump42so that the temperature of the compressed air CA (CA1+CA2) measured by the second temperature sensor44reaches a target temperature. The compressed air CA (CA1+CA2) supplied from the cooling air supply lines L11and L12to the turbine13is used to cool rotors and rotor blades, which are not illustrated. Therefore, it is necessary to maintain the temperature of the compressed air CA (CA1+CA2) to be supplied to the turbine13at a predetermined cooling temperature required for cooling. That is, the rotation speed of the supply pump42is adjusted so that the temperature of the compressed air CA (CA1+CA2) to be supplied to the turbine13is cooled to the predetermined cooling temperature, and the amount of heat removed from the compressed air CA2flowing through the second cooling air supply line L12is adjusted. Here, the control method of the gas turbine10will be described.FIG.2is a graph illustrating a gas turbine output with respect to an intake temperature of the gas turbine. As illustrated inFIG.2, the gas turbine output tends to be reduced as the intake temperature of the gas turbine is increased. Here, the intake temperature of the gas turbine is a temperature of the air to be taken into the compressor11, and is a temperature measured by the first temperature sensor43. The gas turbine output is the amount of power generated by the generator22coupled to the gas turbine10. In general, in the gas turbine10, an operable region with respect to the gas turbine output is set, an upper limit value is a load of 100%, and a lower limit value is a load of La %. In a case in which the supplying amount of the fuel F to the combustor12is reduced, the gas turbine output is reduced. In a case in which the supplying amount of the fuel F is reduced, a combustion temperature decreases, and the amount of hazardous substances (for example, NOx) generated increases. The load of La % as the lower limit value is set based on the regulated amount of the hazardous substances. For example, in a case in which the intake temperature of the gas turbine is 15° C. and the gas turbine output at the load of 100% is 100 MW, the load of La % is 50 MW (La 15). In this case, in a case in which the air A to be taken into the compressor11is heated by the first heat exchanger31, the intake temperature of the gas turbine increases to 20° C. Then, the gas turbine output at the load of La % is 45 MW (La 20). The gas turbine output 45 MW (La 20) at this load of La % is the same as the gas turbine output 45 MW (Lb 15) at a load of Lb % in a case in which the intake temperature of the gas turbine is 15° C. Therefore, the lower limit value in the operable region of the gas turbine10is reduced from the load of La % to the load Lb %, the operable region can be expanded within a range from the load of 100% (100 MW) to the load of Lb % (45 MW). The gas turbine of the first embodiment includes the compressor11that compresses the air A, the combustor12that mixes and combusts the compressed air CA compressed by the compressor11and the fuel F, the turbine13that obtains rotational power using the combustion gas CG generated by the combustor12, the compressed air cooling heat exchanger (the third heat exchanger33) that cools the compressed air CA to produce cooling air for the turbine, the air temperature adjusting heat exchangers (the first and second heat exchangers31and32) that exchange heat between the air A and the compressed air CA, the heat exchange amount adjusting device that adjusts the heat exchange amount of each of the compressed air cooling heat exchanger and the air temperature adjusting heat exchangers, and the control device14that controls the heat exchange amount adjusting device, in which the control device14controls the heat exchange amount adjusting device based on a temperature of the air A to be taken into the compressor11. Therefore, the air temperature adjusting heat exchanger exchanges heat between the air A and the compressed air CA, so that the air A is heated with the compressed air CA, and the air A whose temperature has increased by heating is taken into the compressor11. In this case, the control device14adjusts the heat exchange amount of the air temperature adjusting heat exchanger by the heat exchange amount adjusting device based on the temperature of the air A to be taken into the compressor11. That is, in a case in which the heat exchange amount of the air temperature adjusting heat exchanger is adjusted, a temperature of the air A heated with the compressed air CA is adjusted. Here, since an output of the gas turbine10changes depending on the temperature of the air A to be taken into the compressor11, the output of the gas turbine10can be adjusted to a target output with high accuracy regardless of a load of the gas turbine10, and an operation region can be expanded by the single gas turbine10. In addition, in the first embodiment, the air A to be taken into the compressor11is heated with the compressed air CA that is compressed by the compressor11and used as cooling air for the turbine13. In this case, the compressed air CA that has heated the air A is cooled with the air A and transmitted to the turbine13, so that the compressed air CA is not discarded. Therefore, the heat of the compressed air CA that is used as the cooling air for the turbine13can be efficiently recovered by the air A. In the gas turbine of the first embodiment, the first temperature sensor43that measures a temperature of the air A heat-exchanged by the air temperature adjusting heat exchanger is provided, and the control device14controls the heat exchange amount in the air temperature adjusting heat exchanger by the heat exchange amount adjusting device so that the temperature of the air A measured by the first temperature sensor43approaches a target temperature. Therefore, the temperature of the air A to be taken into the compressor11can be controlled with high accuracy. In the gas turbine of the first embodiment, the second temperature sensor44that measures a temperature of the compressed air CA cooled by the third heat exchanger33is provided, and the control device14controls the heat exchange amount in the third heat exchanger33by the heat exchange amount adjusting device so that the temperature of the compressed air CA measured by the second temperature sensor44is maintained at a target temperature. Therefore, the temperature of the compressed air CA as cooling air to be supplied to the turbine13can be controlled with high accuracy. In the gas turbine of the first embodiment, the air temperature adjusting heat exchanger includes the first heat exchanger31that exchanges heat between the air A and the first medium HW, and the second heat exchanger32that exchanges heat between the compressed air CA and the first medium HW, and the heat exchange amount adjusting device adjusts a heat exchange amount in the second heat exchanger. Therefore, the second heat exchanger32exchanges heat between the compressed air CA and the first medium HW to heat the first medium with the compressed air CA, the first heat exchanger31exchanges heat between the air A and the first medium HW to heat the air A with the first medium HW, and the air A whose temperature has increased by heating is taken into the compressor11. In this case, the control device14adjusts the amount of heat of the compressed air CA to be supplied to the second heat exchanger32by the heat exchange amount adjusting device based on the temperature of the air A to be taken into the compressor. That is, the amount of heat of the compressed air CA is adjusted to increase the temperature of the air A through the first medium HW and the temperature of the air A to be taken into the compressor11can be controlled with high accuracy. In the gas turbine of the first embodiment, the first cooling air supply line L11and the second cooling air supply line L12that are used to supply the compressed air CA compressed by the compressor11to the turbine13as cooling air are provided in parallel, the second heat exchanger32is provided in the first cooling air supply line L11, the third heat exchanger33that exchanges heat between the compressed air CA and the second medium A1is provided in the second cooling air supply line L12, and the flow rate adjusting valves34and35are provided as the heat exchange amount adjusting devices in the first cooling air supply line L11and the second cooling air supply line L12, respectively. Therefore, opening degrees of the flow rate adjusting valves34and35are adjusted to adjust a flow rate of the compressed air CA flowing through the first cooling air supply line L11, so that the amount of heat supplied from the compressed air CA to the first medium HW can be adjusted by the second heat exchanger32provided in the first cooling air supply line L11, and the temperature of the air A to be taken into the compressor11can be adjusted by the first medium HW with high accuracy. In addition, since the third heat exchanger33exchanges heat between the compressed air CA and the second medium A1such as air, and a, material that exists in the vicinity is used, it is possible to shorten a length of a pipe to be used and contribute the miniaturization of equipment and the decrease in cost. The flow rate adjusting valves34and35are provided as the heat exchange amount adjusting devices in both the first cooling air supply line L11and the second cooling air supply line L12, but the flow rate adjusting valves34and35may be provided in any one of the first cooling air supply line L11and the second cooling air supply line L12. The flow rate of the compressed air CA flowing through the first cooling air supply line L11can be directly adjusted by the flow rate adjusting valve34being provided in only the first cooling air supply line L11. In addition, the flow rate of the compressed air CA flowing through the second cooling air supply line L12is adjusted by the flow rate adjusting valve35being provided in only the second cooling air supply line L12, so that the flow resistance of the compressed air CA fluctuates. Thus, the flow rate of the compressed air CA flowing through the first cooling air supply line L11can be indirectly adjusted. In the gas turbine of the first embodiment, the second medium A1is air. Therefore, it is possible to shorten a length of a pipe to be used, achieve the miniaturization of equipment, and suppress the increase in cost by using air that exists in the vicinity. In the gas turbine of the first embodiment, the third heat exchanger33is a cooling tower. Therefore, the structure can be simplified. In addition, the control method of the gas turbine of the first embodiment includes a step of cooling the compressed air CA to be supplied to the turbine13, a step of increasing a temperature of the air A with the compressed air CA, and a step of adjusting the amount of heat of the compressed air CA, which increases a temperature of the air A based on a temperature of the air A to be taken into the compressor11. Therefore, in a case in which the amount of heat of the compressed air CA is adjusted, a temperature of the air A heated with the compressed air is adjusted. Here, since an output of the gas turbine10changes depending on the temperature of the air to be taken into the compressor11, the output of the gas turbine10can be adjusted to a target output with high accuracy regardless of a load of the gas turbine10. Second Embodiment FIG.3is a schematic configuration diagram illustrating a combined plant of a second embodiment. Members having the same functions as those of the first embodiment described above are designated by the same reference numerals, and detailed descriptions thereof will be omitted. In the second embodiment, as illustrated inFIG.3, a combined cycle plant50includes the gas turbine10, a heat recovery steam generator (HRSG)51, a steam turbine52, and a generator53. The gas turbine10includes the compressor11, the combustor12, the turbine13, and the control device14. Since the gas turbine10is substantially the same as the first embodiment described above, the descriptions thereof will be omitted. The heat recovery steam generator51generates steam (superheated steam) ST by exhausted heat of the flue gas EG discharged from the gas turbine10(turbine13) through the flue pas discharge line L5. Although not illustrated, the heat recovery steam generator51includes a superheater, an evaporator, and an economizer as heat exchangers. The heat recovery steam generator51recovers heat in the order of the superheater, the evaporator, and the economizer by passing the flue gas EG from the gas turbine10through the inside of the heat recovery steam generator51to generate the steam ST. The heat recovery steam generator51coupled to a stack61through a flue gas discharge line L6that discharges the used flue gas EG that has generated the steam ST. The steam turbine52is driven by the steam ST generated by the heat recovery steam generator51, and includes a turbine62. In the turbine62, for example, a high-pressure turbine, a medium-pressure turbine, and a low-pressure turbine are integrally rotatably coupled with a rotating shaft. The generator53is coupled to the turbine62with a rotating shaft63. A steam supply line L7that is used to supply the steam ST in the heat recovery steam generator51to the turbine is provided. In the steam turbine52, the turbine62is rotated by the steam ST from the heat recovery steam generator51, and the generator53is driven by rotational power transmitted by the turbine62being rotated. The steam turbine52is provided with a condenser64for cooling the steam ST that drives the turbine62. The condenser64cools the steam discharged from the turbine62with cooling water (for example, seawater) to produce condensed water. The condenser64transmits the generated condensed water as a water supply WS to the heat recovery steam generator51through a water supply line L8. A condensate pump65is provided in the water supply line L8. In addition, the condenser64is provided with a cooling water line L9for cooling the steam ST with cooling water. The water supply line L8is provided with a water supply circulation line (second medium supply line)110that branches from between the condensate pump65and the heat recovery steam generator51. The water supply circulation line L10extends from the water supply line L8, passes through the third heat exchanger33, and returns to the water supply line L8. A flow rate adjusting valve66is provided in the water supply line L8. Therefore, an opening degree of the flow rate adjusting valve66is adjusted to circulate part of the water supply WS flowing in the water supply line L8through the water supply circulation line L10as a second medium. Then, the compressed air CA2flowing through the second cooling air supply line L12is cooled in the third heat exchanger33by the water supply WS flowing through the water supply circulation line L10. It is not limited that the water supply circulation line L10extending toward the third heat exchanger33is provided with the water supply line L8that branches at this position. For example, the water supply circulation line L10may be provided to branch from an internal system of the heat recovery steam generator51. In addition, a returning destination of the water supply circulation line L10is not limited to an upstream side of the heat recovery steam generator51, and the water supply circulation line L10may return to the internal system of the heat recovery steam generator51. Therefore, during the operation of the combined cycle plant50, the compressor11compresses the air A in the gas turbine10, and the combustor12mixes and combusts the compressed air CA supplied and the fuel F. The turbine13is rotationally driven by the combustion gas CG supplied from the combustor12, and the generator22generates electricity. In addition, the flue gas EG discharged from the gas turbine10(turbine13) is transmitted to the heat recovery steam generator51, the heat recovery steam generator51generates the steam ST, and the steam ST is transmitted to the steam turbine52. In the steam turbine52, the turbine62rotationally driven by the steam ST, and the generator53generates electricity. The steam ST used in the turbine62is cooled by the condenser64to be condensed water, and returns to the heat recovery steam generator51as the water supply WS. The control device14controls the first flow rate adjusting valve34and the second flow rate adjusting valve35as the heat exchange amount adjusting devices based on the temperature of the air A to be taken into the compressor11. That is, the control device14adjusts opening degrees of the first flow rate adjusting valve34and the second flow rate adjusting valve35so that the temperature of the air A measured by the first temperature sensor43reaches a target temperature. In addition, the control device14controls the opening degree of the flow rate adjusting valve66based on a temperature of the compressed air CA (CA1+CA2) as cooling air to be supplied to the turbine13. The control device14adjusts the opening degree of the flow rate adjusting valve66so that the temperature of the compressed air CA (CA1+CA2) measured by a second temperature sensor44reaches a target temperature, and the amount of heat removed from the compressed air CA2flowing through the second cooling air supply line L12is adjusted. Here, a control of the gas turbine10in the combined cycle plant50will be described. In a case in which it is desired to shift the gas turbine10in an operating state with a load of 100% (gas turbine output of 100 MW) into an operating state with a partial load (gas turbine output of 45 MW), the control device14reduces the amount of the fuel F to be supplied to the combustor12. Then, the operating state of the gas turbine10is lowered to an operating state (gas turbine output of 50 MW) at a load of La %. The control device14increases the intake temperature of the gas turbine. In this case, the temperature of the air A that flows through the air intake line L1and is heated by the first heat exchanger31is input to the control device14from the first temperature sensor43, and the opening degrees of the first flow rate adjusting valve34and the second flow rate adjusting valve35are adjusted so that the temperature measured by the first temperature sensor43reaches a target temperature. In a case in which the control device14adjusts the opening degrees of the first flow rate adjusting valve34and the second flow rate adjusting valve35to increase the flow rate of compressed air CA1flowing to the first cooling air supply line L11side, a temperature of the first medium HW is increased, and the temperature of air A, that is, the intake temperature of the gas turbine is increased to the target temperature. As a result, the output of the gas turbine10is reduced to 45 MW at a load of La %. In addition, the control device14controls the flow rate adjusting valve66based on a temperature of the compressed air CA (CA1+CA2) as cooling air to be supplied to the turbine13. The control device14adjusts the opening degree of the flow rate adjusting valve66so that the temperature of the compressed air CA (CA1+CA2) measured by the second temperature sensor44reaches a target temperature. Then, a flow rate of the water supply WS to be supplied to the third heat exchanger33is adjusted, and a temperature of the compressed air CA2cooled by the water supply WS is adjusted by the third heat exchanger33. As a result, the compressed air CA (CA1+CA2) cooled to an appropriate temperature can be supplied to the turbine13, and the turbine13can be appropriately cooled. As described above, in the gas turbine or the second embodiment, the second heat exchanger32is provided in the first cooling air supply line L11, the third heat exchanger33that exchanges heat between the compressed air CA and the water supply WS is provided in the second cooling air supply line L12, and the control device14controls the heat exchange amount adjusting devices based on a temperature of the air A to be taken into the compressor11. Therefore, an output of the gas turbine10can be adjusted to a target output with high accuracy regardless of a load of the gas turbine10, and an operation region can be expanded by the single gas turbine10. In the gas turbine of the second embodiment, the second medium is used as the water supply WS that returns to the heat recovery steam generator51. Therefore, the increase in cost can be suppressed by using the water supply WS existing in the vicinity. In addition, the combined cycle plant of the second embodiment is provided with the gas turbine10, the heat recovery steam generator51that generates the steam ST by exhausted heat of the flue gas EG discharged from the gas turbine10, and the steam turbine52that includes the turbine62driven by the steam ST generated by the heat recovery steam generator51. Therefore, regardless of the load of the gas turbine10, an output of the combined cycle plant50in which the gas turbine10is combined with the steam turbine52can be adjusted to a target output. Since a change rate of the steam turbine52during heating of the intake air is smaller than a change rate of the output of the gas turbine10, the operation region in the combined cycle plant50can be expanded by the output adjustment of the gas turbine10during the combined cycle operation. Third Embodiment FIG.4is a schematic configuration diagram illustrating a combined plant of a third embodiment. Members having the same functions as those of the second embodiment described above are designated by the same reference numerals, and detailed descriptions thereof will be omitted. In the third embodiment, as illustrated inFIG.4, a cooling air supply line L15is provided between the compressor11and the turbine13. The cooling air supply line L15is used to supply part of the compressed air CA compressed by the compressor11to the turbine13as cooling air. One end portion of the cooling air supply line L15is coupled to the combustor casing chamber (not illustrated) of the compressor11, and the other end portion is coupled to a space formed inside a rotor (not illustrated) of the turbine13. The second heat exchanger32and the third heat exchanger33are provided in the cooling air supply line L15in series. The third heat exchanger33is provided on an upstream side of the cooling air supply line L15in a direction where the compressed air CA flows, and the second heat exchanger32is provided on a downstream side. A first medium circulation line L13is provided between the first heat exchanger31and the second heat exchanger32. A circulation pump41and a flow rate adjusting valve45are provided in the first medium circulation line L13. The third heat exchanger33is provided in a water supply circulation line L10. The control device14controls the first flow rate adjusting valve45as the heat exchange amount adjusting device based on the temperature of the air A to be taken into the compressor11. The control device14adjusts the opening degree of the flow rate adjusting valve45so that the temperature of the air A measured by the first temperature sensor43reaches a target temperature. Here, a control of the gas turbine10in the combined cycle plant50will be described. In a case in which it is desired to shift the gas turbine10in an operating state with a load of 100% (gas turbine output of 100 MW) into an operating state with a partial load (gas turbine output of 45 MW), the control device14reduces the amount of the fuel F to be supplied to the combustor12. Then, the operating state of the gas turbine10is lowered to an operating state (gas turbine output of 50 MW) at a load of La %. The control device14increases the intake temperature of the gas turbine. In this case, the temperature of the air A that flows through the air intake line L1and is heated by the first heat exchanger31is input to the control device14from the first temperature sensor43, and the opening degree of the flow rate adjusting valve45is adjusted so that the temperature measured by the first temperature sensor43reaches a target temperature. In a case in which the control device14adjusts the opening degree of the flow rate adjusting valve45to increase the flow rate of the first medium HW flowing through the first medium circulation line L13, the heat exchange amount from the first medium HW to the air A is increased by the first heat exchanger31to increase the temperature, and the temperature of air A, that is, the intake temperature of the gas turbine is increased to a target temperature. As a result, the output of the gas turbine10is reduced to 45 MW at a load of La %. In addition, the control device14controls the flow rate adjusting valve66based on the temperature of the compressed air CA as cooling air to be supplied to the turbine13. The control device14adjusts the opening degree of the flow rate adjusting valve66so that the temperature of the compressed air CA measured by the second temperature sensor44reaches a target temperature. Then, a flow rate of the water supply WS to be supplied to the third heat exchanger33is adjusted, and a temperature of the compressed air CA cooled by the water supply WS is adjusted by the third heat exchanger33. As a result, the compressed air CA at an appropriate temperature can be supplied to the turbine13, and the turbine13can be appropriately cooled. As described above, in the gas turbine of the third embodiment, the cooling air supply line L15that is used to supply the compressed air CA compressed by the compressor11to the turbine13as cooling air is provided, the second heat exchanger32and the third heat exchanger33are provided in the cooling air supply line L15in series, and the flow rate adjusting valve45is provided as the heat exchange amount adjusting device in the first medium circulation line L13through which the first medium HW circulates between the first heat exchanger31and the second heat exchanger32. Therefore, the opening degree of the flow rate adjusting valve45is adjusted to adjust a flow rate of the first medium HW flowing through the first medium circulation line L13, so that the amount of heat supplied from the compressed air CA to the first medium HW can be adjusted by the second heat exchanger32provided in the cooling air supply line L15, and the temperature of the air A to be taken into the compressor11can be adjusted by the first medium HW with high accuracy. Here, in the second and third embodiments described above, the third heat exchanger33is, for example, a TCA cooler and may be a cooling tower. Fourth Embodiment FIG.5is a schematic configuration diagram illustrating a gas turbine of a fourth embodiment. Members having the same functions as those of the embodiments described above are designated by the same reference numerals, and detailed descriptions thereof will be omitted. In the fourth embodiment, as illustrated inFIG.5, the gas turbine10includes the first heat exchanger31, the third heat exchanger33, the first flow rate adjusting valve34, and the second flow rate adjusting valve35. In the fourth embodiment, the first heat exchanger31corresponds to the air temperature adjusting heat exchanger of the present invention, and directly exchanges heat between the air A to be taken into the compressor11and the compressed air CA generated by the compressor11. The first heat exchanger31is provided in the air intake line L1. A first cooling air supply line L11and a second cooling air supply line L12are provided in parallel between the compressor11and the turbine13. The first heat exchanger31is provided in the first cooling air supply line L11, and the third heat exchanger33is provided in the second cooling air supply line L12. Therefore, the air A flowing through the air intake line L1is heated with the compressed air CA1flowing through the first cooling air supply line L11by the first heat exchanger31, and the compressed air CA1is cooled. The first flow rate adjusting valve34is provided on an upstream side of the first heat exchanger31in the first cooling air supply line L11. A second flow rate adjusting valve35is provided on an upstream side of the third heat exchanger33in the second cooling air supply line L12. The first flow rate adjusting valve34and the second flow rate adjusting valve35function as heat exchange amount adjusting devices that adjust the amount of heat of the compressed air CA1to be supplied to the first heat exchanger31. The control device14controls the first flow rate adjusting valve34and the second flow rate adjusting valve35as the heat exchange amount adjusting devices based on the temperature of the air A to be taken into the compressor11. The first temperature sensor43measures the temperature of the air A that flows through the air intake line L1and is heated by the first heat exchanger31, and the control device14adjusts the opening degrees of the first flow rate adjusting valve34and the second flow rate adjusting valve35so that the temperature of the air A measured by the first temperature sensor43reaches a target temperature. As described above, the gas turbine of the fourth embodiment includes the first heat exchanger31that directly exchanges heat between the air A and the compressed air CA, the heat exchange amount adjusting devices that adjust the amount of heat of the compressed air CA to be supplied to the first heat exchanger31, and the control device14that controls the heat exchange amount adjusting devices based on a temperature of the air A to be taken into the compressor1. Here, since an output of the gas turbine10changes depending on the temperature of the air A to be taken into the compressor11, the output of the gas turbine10can be adjusted to a target output regardless of a load of the gas turbine10, and an operation region can be expanded by the single gas turbine10. In addition, since heat exchange is directly carried out between the air A to be taken into the compressor11and the compressed air CA generated by the compressor11, the system can be simplified. Fifth Embodiment FIG.6is a schematic configuration diagram illustrating a combined plant of a fifth embodiment. Members having the same functions as those of the embodiments described above are designated by the same reference numerals, and detailed descriptions thereof will be omitted. In the fifth embodiment, as illustrated inFIG.6, the gas turbine10includes the first heat exchanger31, the third heat exchanger33, and the heat exchange amount adjusting devices. In the fifth embodiment, the first heat exchanger31corresponds to the air temperature adjusting heat exchanger of the present invention, and directly exchanges heat between the air A to be taken into the compressor11and the compressed air CA generated by the compressor11. The cooling air supply line L15is provided between the compressor11and the turbine13. The first heat exchanger31and the third heat exchanger33are provided in the cooling air supply line L15in series. That is, the first heat exchanger31is provided in the cooling air supply line L15, and the third heat exchanger33is provided on an upstream side. The third heat exchanger33is provided in the water supply circulation line L10, and the flow rate adjusting valve66is provided in the water supply circulation line L10. In addition, as the heat exchange amount adjusting devices, an air bypass line L16and a flow rate adjusting valve71are provided. One end portion of the air bypass line L16is coupled to an upstream side of the first heat exchanger31in the air intake line L1, and the other end portion is coupled to a downstream side of the first heat exchanger31in the air intake line L1. The flow rate adjusting valve71is provided in the air bypass line L16. The control device14controls the first flow rate adjusting valves66and71as the heat exchange amount adjusting devices based on the temperature of the air A to be taken into the compressor11. The control device14adjusts the opening degrees of the flow rate adjusting valves66and71so that the temperature of the air A measured by the first temperature sensor43reaches a target temperature. That is, in a case in which it not necessary to adjust the temperature of the air A to be taken into the compressor11, the control device14causes the air A to be supplied from the air bypass line L16to the compressor11by the flow rate adjusting valve71being opened without the air A passing through the first heat exchanger31. As described above, in the gas turbine of the fifth embodiment, the first heat exchanger31and the third heat exchanger33are provided in the cooling air supply line L15in series, and the flow rate adjusting valve66is provided as the heat exchange amount adjusting device in the water supply circulation line L10as the second medium supply line through which the water supply WS circulates as the second medium in the third heat exchanger33. Therefore, the opening degree of the flow rate adjusting valve66is adjusted to adjust a flow rate of the water supply WS flowing through the water supply circulation line L10, so that the amount of heat supplied from the compressed air CA to the water supply WS can be adjusted by the third heat exchanger33provided in the cooling air supply line L15, and the temperature of the air A to be taken into the compressor11can be adjusted by the compressed air CA with high accuracy. In the gas turbine of the fifth embodiment, as the heat exchange amount adjusting devices, the air bypass line L16that bypasses the first heat exchanger31and supplies the air A to the compressor11, and the flow rate adjusting valve71provided in the air bypass line L16are provided. Therefore, in a case in which it is not necessary to adjust the temperature of the air A to be taken into the compressor11, the air A can be supplied from the air bypass line L16to the compressor11by the flow rate adjusting valve71without the air passing through the first exchanger31. Here, in the fifth embodiment described above, the third heat exchanger33is, for example, a TCA cooler and may be a cooling tower. Sixth Embodiment FIG.7is a schematic configuration diagram illustrating a gas turbine of a sixth embodiment. Members having the same functions as those of each embodiment described above are designated by the same reference numerals, and detailed descriptions thereof will be omitted. In the sixth embodiment, as illustrated inFIG.7, the gas turbine10includes the first heat exchanger31, the second heat exchanger32, the third heat exchanger33, and the heat exchange amount adjusting device. The first heat exchanger31is provided in the air intake line L1. A cooling air supply line L17is provided between the compressor11and the cooling subject member80. The cooling air supply line L17is used to supply part of the compressed air CA compressed by the compressor11to the cooling subject member80as cooling air. The second heat exchanger32is provided in the cooling air supply line L17. A first medium circulation line L13is provided between the first heat exchanger31and the second heat exchanger32. A circulation pump41and a flow rate adjusting valve45are provided in the first medium circulation line L13. Therefore, the circulation pump41can be driven to circulate the first medium HW between the first heat exchanger31and the second heat exchanger32through the first medium circulation line L13. The third heat exchanger33is provided in the first medium circulation line L13. The circulation pump41and the flow rate adjusting valve45are provided on one side of the first medium circulation line L13where the first medium HW flows from the first heat exchanger31to the second heat exchanger32, and the third heat exchanger33is provided on the other side of the first medium circulation line L13where the first medium HW flows from the second heat exchanger32to the first heat exchanger31. The third heat exchanger33is provided in the second medium supply line L14, and the supply pump42is provided in the second medium supply line L14. The second medium supply line L14causes the second medium (for example, air) A1to flow through the second medium supply line L14. The circulation pump41and the flow rate adjusting valve45may be provided the other side of the first medium circulation line L13where the first medium HW flows from the second heat exchanger32to the first heat exchanger31, and the third heat exchanger33may be provided on one side of the first medium circulation line L13where the first medium HW flows from the first heat exchanger31to the second heat exchanger32. The control device14controls the supply pump42as the heat exchange amount adjusting device based on the temperature of the air A to be taken into the compressor11. The control device14adjusts a rotation speed of the supply pump42so that the temperature of the air A measured by the first temperature sensor43reaches a target temperature. In addition, a third temperature sensor46that measures a temperature of the compressed air CA between the second heat exchanger32and the cooling subject member80is provided in the cooling air supply line L17. The control device14controls the flow rate adjusting valve45based on the temperature of the compressed air CA cooled by the second heat exchanger32. The control device14adjusts the opening degree of the flow rate adjusting valve45so that the temperature of the compressed air CA measured by the third temperature sensor46reaches a target temperature. As described above, in the gas turbine of the sixth embodiment, while heat exchange is carried out between part of the compressed air CA bled from the compressor11and the first medium HW by the second heat exchanger32to supply the cooled compressed air CA to the cooling subject member80, heat exchange is carried out between the heated first medium HW and the air A by the first heat exchanger31, and the control device14controls the supply pump42so that the temperature of the air A reaches a target temperature. Therefore, an output of the as turbine10can be adjusted to a target output with high accuracy regardless of a load of the gas turbine10, and an operation region can be expanded by the single gas turbine10. In the gas turbine of the present embodiment, the third heat exchanger33as the compressed air cooling heat exchanger is provided in the first medium circulation line L13that circulates the first medium HW between the first heat exchanger31and the second heat exchanger32. Therefore, the first heat exchanger31, the second heat exchanger32, and the third heat exchanger33can be disposed in the first medium circulation line L13, which enables the device to be compact. Seventh Embodiment FIG.8is a schematic configuration diagram illustrating a gas turbine of a seventh embodiment. Members having the same functions as those of the sixth embodiment described above are designated by the same reference numerals, and detailed descriptions thereof will be omitted. In the seventh embodiment, as illustrated inFIG.8, the gas turbine10includes the first heat exchanger31, the second heat exchanger32, the third heat exchanger33, and the heat exchange amount adjusting device. The first heat exchanger31is provided in the air intake line L1. The cooling air supply line L17is provided between the compressor11and the cooling subject member80. The second heat exchanger32is provided in the cooling air supply line L17. A first medium circulation line L13is provided between the first heat exchanger31and the second heat exchanger32. The circulation pump41, the flow rate adjusting valve45, and the third heat exchanger33are provided in the first medium circulation line L13. The circulation pump41, the flow rate adjusting valve45, and the third heat exchanger33are provided on one side of the first medium circulation line L13where the first medium HW flows from the first heat exchanger31to the second heat exchanger32. The circulation pump41, the flow rate adjusting valve45, and the third heat exchanger33may be provided on the other side of the first medium circulation line L13where the first medium HW flows from the second heat exchanger32to the first heat exchanger31. The control device14controls the first flow rate adjusting valve45as the heat exchange amount adjusting device based on the temperature of the air A to be taken into the compressor11. The control device14adjusts the opening degree of the flow rate adjusting valve45so that the temperature of the air A measured by the first temperature sensor43reaches a target temperature. In addition, the control device14controls the supply pump42based on the temperature of the compressed air CA cooled by the second heat exchanger32. The control device14adjusts a rotation speed of the supply pump42so that the temperature of the compressed air CA measured by the third temperature sensor46reaches a target temperature. As described above, in the gas turbine of the seventh embodiment, while heat exchange is carried out between part of the compressed air CA bled from the compressor11and the first medium HW by the second heat exchanger32to supply the cooled compressed air CA to the cooling subject member80, heat exchange is carried out between the heated first medium HW and the air A by the first heat exchanger31, and the control device14controls the flow rate adjusting valve45so that the temperature of the air A reaches a target temperature. Therefore, an output of the as turbine10can be adjusted to a target output with high accuracy regardless of a load of the gas turbine10, and an operation region can be expanded by the single gas turbine10. Eighth Embodiment FIG.9is a schematic configuration diagram illustrating a gas turbine of an eighth embodiment. Members having the same functions as those of the embodiments described above are designated by the same reference numerals, and detailed descriptions thereof will be omitted. In the eighth embodiment, as illustrated inFIG.9, the gas turbine10includes the first heat exchanger31, the second heat exchanger32, the third heat exchanger33, and the heat exchange amount adjusting device. The first heat exchanger31is provided in the air intake line L1. The cooling air supply line L17is provided between the compressor11and the cooling subject member80. The second heat exchanger32, the first heat exchanger31, and the third heat exchanger33are provided from an upstream side of the cooling air supply line L17in a direction where the compressed air CA flows, in this order. In addition, in the cooling air supply line L17, a supply pump91is provided between the first heat exchanger31and the third heat exchanger33. The second heat exchanger32is provided in a third medium supply line L18, and a supply pump92is provided in the third medium supply line L18. The third medium supply line L18causes a third medium (for example, air) A2to flow through the third medium supply line L18. The third heat exchanger33is provided in the second medium supply line L14, and the supply pump42is provided in the second medium supply line L14. The control device14controls the supply pump92as the heat exchange amount adjusting device based on the temperature of the air A to be taken into the compressor11. The control device14adjusts a rotation speed of the supply pump92so that the temperature of the air A measured by the first temperature sensor43reaches a target temperature. In addition, the control device14controls the supply pump42based on the temperature of the compressed air CA cooled by the third heat exchanger33. The control device14adjusts a rotation speed of the supply pump42so that the temperature of the compressed air CA measured by the third temperature sensor46reaches a target temperature. As described above, in the gas turbine of the eighth embodiment, heat exchange is carried out between part of the compressed air CA bled from the compressor11and the third medium A2by the second heat exchanger32, heat exchange is carried out between the compressed air CA whose temperature is adjusted and the air A by the first heat exchanger31, and the cooled compressed air CA is supplied to the cooling subject member80. On the other hand, the control device14controls the supply pump92so that the temperature of the air A reaches a target temperature. Therefore, an output of the gas turbine10can be adjusted to a target output with high accuracy regardless of a load of the gas turbine10, and an operation region can be expanded by the single gas turbine10. The configurations of the air bypass line L16and the flow rate adjusting valve71in the fifth embodiment may be used in the first to fourth embodiments and the sixth to eighth embodiments. In that case, the entire system may be used as a single gas turbine or a combined plant. For example, in a case in which the configuration of the air bypass line L16and the flow rate adjusting valve71is applied to the first, second, and fourth embodiments, the control performed by the flow rate adjusting valves34and35may be stopped. In a case in which the configuration of the air bypass line L16and the flow rate adjusting valve71is applied to the third embodiment, the control performed by the flow rate adjusting valves45and66may be stopped. In addition, in a case in which the configuration of the air bypass line116and the flow rate adjusting valve71is applied to the sixth to eighth embodiments, the control performed by the flow rate adjusting valve45, and the supply pumps42and92may be stopped. In addition, in the above-described embodiments, the temperature of the air A to be taken into the compressor11is measured by the first temperature sensor43provided in the air intake line L11, but the present invention is not limited to this configuration. For example, the temperature of the air to be taken into the compressor may be set to an outside air temperature, or a temperature set according to seasons, weather, time, or the like may be used. In addition, in the above-described embodiments, the turbine13and the cooling subject member80are applied as members subjected to temperature adjustment, and the air for heat exchange is used as the cooling air, so that the turbine13and the cooling subject member80are cooled with the cooling air, but the present invention is not limited to this configuration. For example, a configuration in which a heating subject member is applied as a member subjected to temperature adjustment, the air for heat exchange is used as heating air, and the heating subject member is heated with the heating air may be adopted. In addition, the single gas turbine or the combined plant of the present invention is applied in the above-described first to eighth embodiments, but the present invention in which the single gas turbine is applied can be applied to the combined plant. Conversely, the present invention in which the combined plant is applied can also be applied to the single gas turbine. In addition, a plurality of the heat exchange amount adjusting devices applied in individual embodiments can be applied in combination. REFERENCE SIGNS LIST 10Gas turbine11Compressor12Combustor13Turbine14Control device21Rotating shaft22Generator31First heat exchanger (air temperature adjusting heat exchanger)32Second heat exchanger (air temperature adjusting heat exchanger)33Third heat exchanger (compressed air cooling heat exchanger)34First flow rate adjusting valve (heat exchange amount adjusting device)35Second flow rate adjusting valve (heat exchange amount adjusting device)41Circulation pump42Supply pump43First temperature sensor44Second temperature sensor45Flow rate adjusting valve (heat exchange amount adjusting device)46Third temperature sensor50Combined cycle plant51Heat recovery steam generator52Steam turbine53Generator61Stack62Turbine63Rotating shaft64Condenser65Condensate pump66Flow rate adjusting valve (heat exchange amount adjusting device)71Flow rate adjusting valve (heat exchange amount adjusting device)80Cooling subject member91Supply pump92Supply pumpL1Air intake lineL2Compressed air supply lineL3Fuel gas supply lineL4Combustion gas supply lineL5Flue gas discharge lineL6Flue gas discharge lineL7Steam supply lineL8Water supply lineL9Cooling water lineL10Water supply circulation line (second medium supply line)L11First cooling air supply lineL12Second cooling air supply lineL13First medium circulation lineL14Second medium supply lineL15Cooling air supply lineL16Bypass lineL17Cooling air supply lineL18Third medium supply lineA AirA1Second mediumA2Third mediumCA, CA1, CA2Compressed airCC Combustion gasEG Flue gasF FuelHW First mediumST SteamWS Water supply | 58,014 |
11859549 | DETAILED DESCRIPTION The present disclosure relates to a closed loop heat engine or heat pump system comprising a compressor system and/or a turbine system of the present disclosure. In operation a working fluid is passed through the compressor and turbine. At the same time, a compressor heat transfer medium (for example a coolant for removal of heat from the working fluid in the compressor) is passed through the body of the compressor module, and a turbine heat transfer medium (for example a heating medium for addition of heat to the working fluid in the turbine) is passed through the body of the turbine module. A thermodynamic apparatus comprising the turbine system and compressor system of the present disclosure may be used in power generation applications using regenerative, reheated, intercooled closed cycle turbo machinery. A turbine module of the present disclosure may be operable to approximate isothermal expansion. A compressor of the present disclosure may approximate isothermal compression. Hence the turbine module and compressor module may be included into a heat engine based on a closed cycle gas turbine arrangement for producing power from a heat source. This arrangement of equipment may provide a heat engine which operates in a manner approximating the Ericsson thermodynamic cycle. Hence the thermodynamic apparatus may be provided a closed cycle gas turbine that may be driven by a heated fluid source and a cooled fluid source to rotate a shaft, and hence provide a power output. A thermodynamic apparatus comprising the turbine system and compressor system of the present disclosure may be used in refrigeration applications (i.e. to operate as a heat pump). Hence the thermodynamic apparatus may be provided a closed cycle gas turbine that may be driven by a motor to provide a power input, and hence move heat from a heat source to a heat sink. The apparatus of the present disclosure may also include equipment operable to control, start and stop and seal the machinery. The present disclosure may also relate to a method of manufacture and assembly of a compressor, turbine and regenerative heat exchanger according to the present disclosure. FIG.1shows a schematic representation of a thermodynamic apparatus10(which may be configured as a heat engine or heat pump) including a cooled compressor100, a heated turbine200, a fluid heater6(configured to be in heat flow communication with a heat source), a fluid cooler5(configured to be in heat flow communication with a heat sink) and a recuperator (heat exchanger)300to create the thermodynamic apparatus10. As a heat engine, this can be used to drive a generator4, or alternatively a propulsion shaft and propeller, a compressor, pumps or other power consuming equipment. It can also power combinations of these items. As a heat pump, power is input into the shaft. Both may comprise turbine inter-stage heating and a nozzle heater, and a compressor with cooled diaphragm blading and inter-stage cooling according to the present disclosure herein described. It provides a heat engine or heat pump with extremely high thermodynamic efficiency, and a simple design which can be manufactured using the components as described. Heat sources can include but are not limited to: burning fuel, reactors, thermal solar and/or geothermal. InFIG.1the heater fluid supply and return, and cooler fluid supply and return pipework, is shown as a single line for illustration purposes only. Each of these pipes can pass through a manifold, and split into the many supply and return lines to provide fluid at the same temperature to each heating or cooling element. As presented inFIGS.2,3,5to10, a thermodynamic apparatus10according to the present disclosure comprises a compressor module100, a turbine module200, and a regenerative heat exchanger300centred on a central axis12. The compressor module100, a turbine module200, and a regenerative heat exchanger300are arranged in series along the central axis12such that the regenerative heat exchanger300is provided between the compressor module100and the turbine module200. As shown inFIGS.7,8, the regenerative heat exchanger300defines two flow paths302,304. The first flow path302is operable to deliver working fluid from the compressor module100to the turbine module200, and the second flow path304is operable to deliver working fluid from the turbine module200to the compressor module100. The paths302,304are in heat transfer communication with one another. That is to say, the first flow path302and second flow path304are configured so that heat energy may be transferred between them. For example, the flow paths302,304may be adjacent one another, divided by a wall with an appropriate heat transfer characteristic. The regenerative heat exchanger300may be configured to be counter flow. That is to say, the first flow path302and second flow path304may be arranged such that working fluid flows in a first direction along the first flow path302from the compressor module100to the turbine module200, and in a second direction along the second flow path304from the turbine module200to the compressor module100. Hence the first direction may be opposite to the second direction, such that a counter flow is provided. In an example in which the thermodynamic apparatus is a heat engine the regenerative heat exchanger300is operable (i.e. configured to) transfer heat energy from the second path304to the first path302, and thereby transfer energy from the working fluid in the second path304(i.e. working fluid being delivered from the turbine module200to the compressor module100) to the working fluid in the first path302(i.e. working fluid being delivered from the compressor module100to the turbine module200). In an example in which the thermodynamic apparatus is a heat pump, the regenerative heat exchanger300is operable (i.e. configured to) transfer heat energy from the first path302to the second path304, and thereby transfer energy from the working fluid in the first path302(i.e. working fluid being delivered from the compressor module100to the turbine module200) to the working fluid in the second path304(i.e. working fluid being delivered from the turbine module200to the compressor module100). The regenerative heat exchanger300may have a design of simple construction using a low number of simple parts (minimum of three, shown assembled inFIG.17) which can be manufactured using common manufacturing techniques (machining, forging, casting, additive manufacture) ensuring low cost. The design also allows for a high surface area (increasing heat exchange and efficiency), low flow friction losses and for the channels in each side of the working fluid to be optimised in shape and size to achieve an efficient heat transfer with minimal flow losses. The main components include two heat exchanger plates (FIGS.26to31) and a flow guide (FIGS.32,33). The apparatus further comprises a shaft14centred on, and rotatable about, the central axis12. The shaft14extends through the compressor module100, the turbine module200, and regenerative heat exchanger300. The compressor module100comprises at least one rotor120(i.e. compressor rotor stage). The turbine module200comprises at least one rotor220(i.e. turbine rotor stage). Both rotors120,220are carried on and rotatable with the shaft14. Each of the compressor module100, turbine module200, and regenerative heat exchanger300are enclosed by a common casing400. Hence the thermodynamic apparatus10further comprises a casing400. As shown inFIG.4, the casing400extends around the compressor module100, turbine module200, and regenerative heat exchanger300. Also as shown inFIG.4, the casing400may be substantially cylindrical. That is to say, the casing400may be substantially cylindrical along its length. Put another way, the casing400may have an external surface which extends parallel to the central axis12along the length of the casing400. One or both ends of the casing400may be provided with a flange401for connection with an end plate402. In an alternative example the casing400may have different alternative external geometry, while still enclosing all of the compressor module100, turbine module200, and regenerative heat exchanger300. The casing400may be provided as a casing assembly. Hence the casing may comprise at least two modules (i.e. elements, pieces or segments) which are assembled to form the casing400. The arrangements shown inFIG.2,3show variations of the design shown inFIG.1. In these the relative position of the compressor module100, turbine module200, regenerative heat exchanger300and casing400are shown. As will be described, the compressor module100comprises heat exchangers to cool working fluid passing therethrough, and the turbine module200comprises heat exchangers to heat working fluid passing therethrough. InFIG.2the low pressure side of the working fluid is contained next to the casing400and in a working fluid return channel. InFIG.3the high pressure fluid is next to the casing and in the working fluid return channel. FIG.4shows an example of the thermodynamic apparatus10when assembled, andFIG.5shows the apparatus10with the casing400removed. In use, the casing400is pressurised, and a closed cycle loop is defined by the compressor module100, a regenerative heat exchanger300and turbine module200. As shown inFIGS.7,8,9,10,12to14the compressor module100, a turbine module200, and a regenerative heat exchanger300define a working fluid flow duct20. The working fluid flow duct20defines a closed loop, and hence is configured to be a closed cycle system. The working fluid flow duct20extends, in series, through a compressor module inlet102to a compressor module outlet122; the first path302through the regenerative heat exchanger300; a turbine module inlet202to the turbine module outlet222; a first intermediate duct22provided in (i.e. defined by) the turbine module200; the second path304through the regenerative heat exchanger300, which is in heat transfer communication with the first path302; a second intermediate duct24provided in (i.e. defined by) the compressor module100, which leads back to the compressor module inlet102. In the example shown inFIGS.7,8the thermodynamic apparatus comprises a compressor module100made up of two compressor stages arranged in series, and a turbine module200made up of two turbine stages. Each stage comprises a respective rotor120,220and a first heat exchanger110,210. In some examples, not shown, the compressor module100may comprise a single compressor stage, and the turbine module200may comprise a single turbine stage. Hence in the description reference to the compressor or turbine module inlet or outlet may refer to the module assembly as whole (as shown inFIG.7,8, where the compressor inlet102is the inlet to the whole compressor module assembly, and the outlet122is the outlet for the whole compressor assembly, and the turbine inlet202is the inlet to the whole turbine module assembly, and the outlet222is the outlet for the whole turbine assembly) or to a region in the working flow duct20which defines the end of one stage and the beginning of another (as shown inFIGS.12,13,14where the compressor module/stage inlet102is shown upstream of the first heat exchanger110and the compressor module/stage outlet122is shown downstream of the second heat exchanger150. The regenerative heat exchanger300may comprise a single stage, for example as shown inFIG.7,8, or may comprise a plurality of stages (for example two stages) as shown in the example ofFIG.10. Hence an example comprising a plurality of stages may be operable to increase the amount of heat transferred to the working fluid passing through the working fluid flow duct20. As illustrated inFIG.8, the compressor module100defines a first portion26of the working fluid flow duct20. The first portion26extends between the compressor module inlet102and the compressor module outlet122. In the example shown the first portion comprises two compressor modules100. As shown inFIGS.7,8,9,10,12to14, each stage of the compressor module100comprises a first heat exchanger110and the compressor rotor120, each being provided in the working fluid flow duct20. The first heat exchanger110is provided in flow series between the compressor module inlet102and the compressor rotor120. The compressor rotor120is provided in flow series between the first heat exchanger110and the compressor module outlet122. The first heat exchanger110is defined by a wall112having an external surface114which is located in the working fluid flow duct20. A heat transfer unit130defines the first portion26of the working fluid flow duct20. The first heat exchanger110is in heat transfer communication with the heat transfer unit130via a first main passage134for a first heat transfer medium (i.e. a coolant). The first heat exchanger110is configured such that it is operable to transfer heat to the heat transfer unit130from the working fluid passing the first heat exchanger110. The turbine module200defines a second portion28of the working fluid flow duct20which extends between a turbine module inlet202and a turbine module outlet222. The turbine module222is configured to expand a working fluid as the working fluid passes along the working fluid flow duct20. Each stage of the turbine module200comprises a first heat exchanger210and the turbine rotor220, each being provided in the working fluid flow duct20. The first heat exchanger210is provided in flow series between the turbine module inlet202and the turbine rotor220. The turbine rotor220is provided in flow series between the first heat exchanger210and the turbine module outlet222. The first heat exchanger210is defined by a wall212having an external surface214which is located in the working fluid flow duct20. A heat transfer unit230defines a portion232of the working fluid flow duct20in flow series between the turbine rotor220and turbine module outlet222. The first heat exchanger210is in heat transfer communication with the heat transfer unit230via a second main passage234for a second heat transfer medium. The first heat exchanger210is configured such that it is operable to transfer heat received from the heat transfer unit230to the working fluid passing the first heat exchanger210. As shown in figures, the working fluid flow duct20may be serpentine. That is to say the working fluid flow duct may comprise a plurality of sections which extend at an angle, for example at a right angle, to the central rotational axis12. Put another way, the working fluid flow duct20may comprise a number of sections which extend radially relative to the central rotational axis12. The radially extending sections may be joined by longitudinally extending or curved sections. That is to say the radially extending sections may be linked to one another by further sections which extend in a direction which has a component which extends parallel to the central axis12. These further/joining sections are in part defined by the rotor stages120,220. The heat exchangers110,150,210,250are located in the radially extending sections of the working fluid flow duct20. Providing the working fluid flow duct20with a serpentine configuration means that the surface area of the working fluid flow duct20may be maximised for the length of the apparatus10. The working fluid flow duct20may have such a serpentine flow route through each of the compressor stage(s), turbine stage(s) and regenerative heat exchanger stage(s). As shown inFIGS.6,7,9,11the first main passage134of the compressor module100and second main passage234of the turbine module200each comprise an inlet plenum140,240and an outlet plenum142,242. The inlet plenum140and outlet plenum142of the compressor100are in fluid flow communication via a compressor first sub-passage144defined by the compressor heat transfer unit130for the transfer of the respective heat transfer medium through the compressor first heat exchanger110. The inlet plenum240and outlet plenum242of the turbine100are in fluid flow communication via a turbine first sub-passage244defined by the turbine heat transfer unit230for the transfer of the respective heat transfer medium through the turbine first heat exchanger210. Each inlet plenum140,240has an inlet146,246for communication with a different source of heat transfer medium, and each outlet plenum142,242has an outlet148,248to exhaust the respective heat transfer medium. That is to say, the compressor inlet plenum142has an inlet146for communication with a source of a heat transfer medium which is a cooling medium (i.e. a coolant) and the compressor outlet plenum142has an outlet148to exhaust the coolant from the first main passage134. Likewise the turbine inlet plenum242has an inlet246for communication with a source of heating medium (for example a heated fluid), and the turbine outlet plenum240has an outlet248to exhaust the heating medium from the second main passage234. As shown inFIGS.7,7A,11,12to14the first sub-passages144,244of the compressor module and turbine module extend through the first heat exchanger110,210.FIG.7Ashows an alternative arrangement to that shown inFIG.7, and may be applied to the compressor module and/or turbine module heat exchangers.FIG.11shows a sectional view of a compressor100and/or turbine200according to the present invention. That is to say, the compressor100and turbine200may have the same features as one another, and the features are indicated in FIG.11using reference numerals of the compressor100and turbine200. InFIGS.12,13,14the top half of the figure relate to the turbine module200(with flow through the working fluid flow duct20being from left to right), and the bottom half of the figures relate to the compressor module100(with flow through the working fluid flow duct20being from right to left). The first heat exchanger110,210is in flow series between a first inlet160,260to the first sub-passage144,244and a first outlet162from the first sub-passage144,244. The first inlet160,260is configured to receive heat transfer medium from the inlet plenum140,240. The first outlet162,262is configured to exhaust into the outlet plenum142,242. As shown inFIGS.7to10,12to14each stage of the compressor module100may comprise a second heat exchanger150located in the working fluid flow duct20in flow series between the compressor rotor120and the compressor module outlet122in the heat transfer unit130. The compressor second heat exchanger150is defined by a wall152having an external surface154which is located in the working fluid flow duct20. The second heat exchanger150is configured such that it is operable to transfer heat to the heat transfer unit130from the working fluid passing the second heat exchanger150. Each stage of the turbine module200may comprise a second heat exchanger250which is located in the working fluid flow duct20in flow series between the turbine rotor stage220and the turbine module outlet222in the heat transfer unit230. The compressor second heat exchanger250defined by a wall252having an external surface254which is located in the working fluid flow duct20. The second heat exchanger250is configured such that it is operable to transfer heat received from the heat transfer unit230to the working fluid passing the second heat exchanger250. Hence since a compressor module100and a turbine module200may comprise multiple stages, there may be several pairs of first heat exchangers and second heat exchangers in the working fluid flow duct20defined by each of the compressor module and turbine module. In an alternative example the compressor module and turbine module may comprise a single stage, in which case only a first heat exchanger and second heat exchanger may be provided in the section of the working fluid flow duct20which extends through each of the compressor module100and turbine module200. In each of the compressor module100and turbine module200the first sub-passage144,244extends through the second heat exchanger150,250. As shown in the example ofFIG.12, in each of the compressor module100and turbine module200a second sub-passage170,270extends through the second heat exchanger150,250. The second heat exchanger150,250is in flow series between a second inlet172,272to the second sub-passage170,270and a second outlet174,274from the second sub-passage170,270. The second inlet172,272is configured to receive heat transfer medium from the inlet plenum140,240. The second outlet174,274is configured to exhaust into the outlet plenum142,242. In each of the compressor module100and turbine module the first heat exchanger110,210is provided in series along/in the first sub-passage144,244between the first inlet160,260and the second heat exchanger150,250, and the second heat exchanger150,250is provided in flow series between the first heat exchanger110,210and the first outlet162,262from the first heating medium flow sub-passage144,244. As shown in an alternative example ofFIG.13the first sub-passage144,244may comprise a first node180between the first inlet160,260and the first heat exchanger110,210where the sub-passage splits/diverges to form a first branch184and second branch186. A second node190is provided between the outlet162,262and the second heat exchanger150,250where the first branch184and second branch186join. The first branch184of the first sub-passage144,244extends through the first heat exchanger110,210and bypasses the second heat exchanger150,250. The second branch186bypasses the first heat exchanger110,210and extends though the second heat exchanger150,250. As shown in an alternative example ofFIG.14the first sub-passage144,244may comprise a third sub-passage188,288which extends from a second inlet189,289in fluid communication with the inlet plenum140,240through the second heat exchanger150,250. The third sub-passage188,288joins the first sub-passage144,244between the outlet of the first heat exchanger110,210and first sub-passage outlet144,244such that flow through the first inlet160,260and second inlet189,289exit through the first outlet162,262. InFIGS.12to14the connection to the plenums140,142and240242is indicated with arrows, which indicates that at the inlets and outlets to the sub-passages there is a fluid connection to the plenums. FIG.16shows a3dimage of the heat exchange module inFIG.13—heat exchange fluid is supplied and returned from a single supply and return which simplifies the heating and cooling supplies at the expense of efficiency. FIG.15shows an alternative exploded view of a compressor module of the thermodynamic apparatus, although equally applies to a turbine module. It shows flow paths through and defined by a casing section402, working fluid flow guide404and sections of the heat transfer unit130. The first inlet160to the first sub-passage144and first outlet162are shown. A key feature of the design is that plates are used to create the heat exchangers. For example, two machined inner casing plates are used to create a single sealing face, which is clamped together using a bolted joint arrangement. The internal surface/volume of this pair of plates hold the heat transfer fluid, with a single sealing surface. The plates clamp around a flow path guide assembly. This fits within slotted holes which define heat exchangers and restricts the flow of the heat transfer fluid to the optimum path through the space. This can be made up from a single flat plate, with a number of slotted holes which a number of shaped guide plates fit into, or a single machined or3dprinted item. When connected together these three plates create a heat exchanger with the heat transfer fluid contained within the inner casing plates. FIG.16shows a sectional view of a heat exchanger assembly of the thermodynamic apparatus shown inFIG.13. In this example three cross-linked internal heat transfer flow passages are provided, so only one supply and return is required, for example as shown inFIG.14. FIG.17shows a sectional view of a regenerative heat exchanger of the thermodynamic apparatus.FIG.17shows one half of the regenerative heat exchanger assembly. Rounded edges are shown on the inlet/outlet of the low pressure side slots which improve air flow. FIGS.18to21show different elements of the compressor, turbine and plenum structure of the thermodynamic apparatus.FIGS.18to20show possible combined structural support arrangements and components which make up the supply and return plenum detailed as parts140,142,240and242. This provides support to the compressor and turbine structure and also a means of simple manufacture of the support assembly. InFIG.18there is shown supply and return502of hot and cold heat exchange fluid. Also shown is a return504for seal leak/control line and a sliding seal506for supply and return. InFIG.19there is shown a support structure500for the internal stages. InFIG.20is shown internal restraints508.FIG.20shows a possible arrangement where there are multiple plenums to allow for increased heat transfer fluid flow. It also allows for the return of fluid from the seal drains. The seal drains allow leaking fluid to be captured and re-used. InFIG.21is shown alternative arrangements510for supply and return of heat transfer fluids. For simplicity, only barrel type arrangements are shown but equivalent horizontal and vertical split casing designs are possible to allow for assembly. FIG.22shows a sealing arrangement of use in the apparatus of the present disclosure. FIG.23shows a sectional view of the thermodynamic apparatus shown inFIG.7.FIG.23shows a cross section with a horizontal rather than vertical split in the turbine and compressor casing. FIGS.24,25shows detailed views of a regenerative heat exchanger which forms a part of the thermodynamic apparatus. FIGS.26to31illustrate example components of the regenerative heat exchanger shown inFIG.16. FIGS.32,33shows an example component of the regenerative heat exchanger shown inFIG.16. FIG.34shows an alternative arrangement which can be used to support a set of multiple heat exchanger assemblies, for insertion into a barrel type casing. An arrangement of long studs or bolts600pass through all of the plates. Dowels which link the plate faces (in shear) allow for the casing to be accurately assembled. The thermodynamic apparatus may be configured to operate as a heat engine. With reference toFIGS.7,8,10, in use, the operation of the thermodynamic apparatus involves coupling the inlet plenum140to a heat sink (e.g. source of cold fluid) and the coupling of the inlet plenum242a heat source, so that each are supplied with a heat transfer fluid/medium. The heat transfer fluid in the first main passage134must be provided to be colder than the heat transfer fluid in the second main passage234. The outlet plenum142in outlet plenum242may exhaust back to the heat sink and heat source respectively, or maybe the directed elsewhere. A working fluid is provided in the working fluid flow duct20. The different heat transfer fluid fluids are pumped from their source, through the main passages134,234and leave the apparatus. This temperature differential causes the flow of the working fluid through the working fluid flow duct20. The working fluid will travel around the working fluid flow duct20from the compressor module inlet102, through the compressor module100to the compressor module outlet122, then through the first path302through the regenerative heat exchanger300, then through the turbine module inlet202, through the turbine module200to the turbine module outlet222, then through the first intermediate duct22, then through the second path304through the regenerative heat exchanger300, which is in heat transfer communication with the first path302, and through the second intermediate duct24to the compressor module inlet102. The flow of working fluid results in the turning of the rotors120,220and hence turning the shaft12which may be coupled to a power offtake, and hence be used to drive another piece of apparatus, for example a generator. The power output of the machine can be controlled through the addition and removal of working fluid from the system (increasing and decreasing the pressure and density of the fluid) or by altering the rotational speed of the rotor and shaft. Ideal positions for this which allow for addition and removal of working fluid without an additional compressor are shown inFIG.8. In an alternative example, the thermodynamic apparatus may be configured to operate as a heat pump. In such an example the shaft14is driven by a motor to move the working fluid around the working fluid flow duct20, causing heat exchange across the regenerative heat exchanger to transfer heat from the heat transfer medium in the compressor to the heat transfer medium in the turbine. In such an example the compressor temperature would be higher than the turbine temperature. The configuration of the apparatus of the present disclosure results in a heat engine or heat pump of increased thermal efficiency and power output, and hence one that provides reduced running costs compared to examples of the related art. Hence a thermodynamic apparatus according to the present disclosure will be smaller and cheaper than examples of the related art, giving a significant competitive advantage. The internal routing of the heat exchangers of the compressor and turbine increases heat transfer and hence effectiveness of the cooling of working fluid passing through the compressor and heating are working fluid passing through the turbine. The improved design for electrical power production marine or other propulsion arrangements (for example engines/power units for trains) of this invention can provide a benefit by decreasing fuel consumption (i.e. increasing the range or performance of vessels), by minimising the need for high pressure fluid pipework (i.e. providing a safe design concept) and by simplifying the supporting systems required to operate propulsion equipment (i.e. cheaper and simpler design). The apparatus of the present disclosure is encapsulated in a single casing, reducing part count, overall size of the machine, reduced piping (resulting in lower losses), reduced sealing requirements, and removes the need for external regenerative heat exchangers. This improves the efficiency of the machine. The turbine module and compressor module of the present disclosure may increase the thermal efficiency of a heat engine or heat pump in which they are included over currently available systems and has reduced requirements for space and supporting systems over conventional power generation and cooling equipment having similar thermal efficiency. This has the effect of making equipment of the present disclosure cheaper than the alternatives for the same power rating, giving a significant competitive advantage. The apparatus of the present disclosure may be employed as constant speed machinery for electrical power production (for example where a heat source is created to drive a turbine). It may also be used in constant speed machinery for electrical power using fuels or heat sources. It may also have utility as variable speed machinery for marine or other propulsion. Both electrical power production and the marine propulsion arrangements of apparatus of the present invention may provide benefit maritime applications by decreasing fuel consumption, and hence increasing the range or performance of vessels, by minimising the need for high pressure fluid pipework (making a safer product) and by simplifying the supporting systems required to operate the propulsion equipment (i.e. making cheaper and simpler design). It may also find application in power production from any heat source (as described previously) including commercial power plants, traditional fossil fuel fired power stations, combined cycle power stations, geothermal power and automotive applications. Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. | 33,272 |
11859550 | DETAILED DESCRIPTION Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “forward” and “aft” refer to relative positions within a gas turbine engine or vehicle and refer to the normal operational attitude of the gas turbine engine or vehicle. For example, with regard to a gas turbine engine, forward refers to a position closer to an engine inlet and aft refers to a position closer to an engine nozzle or exhaust. The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. The terms “coupled,” “fixed,” “attached to,” and the like refer to both direct coupling, fixing, or attaching, as well as indirect coupling, fixing, or attaching through one or more intermediate components or features, unless otherwise specified herein. The singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Further, as used herein, the terms “axial” or “axially” refer to a dimension along a longitudinal axis of an engine. The term “forward” used in conjunction with “axial” or “axially” refers to a direction toward the engine inlet, or a component being relatively closer to the engine inlet as compared to another component. The term “aft” or “rear” used in conjunction with “axial” or “axially” refers to a direction toward the engine exhaust, or a component being relatively closer to the engine exhaust as compared to another component. The terms “radial” or “radially” refer to a dimension extending between a center longitudinal axis (or centerline) of the engine and an outer engine circumference. Radially inward is toward the longitudinal axis and radially outward is away from the longitudinal axis. Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. The approximating language may refer to being within a +/−1, 2, 4, 10, 15, or 20 percent margin in either individual values, range(s) of values, and/or endpoints defining range(s) of values. Here and throughout the specification and claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. Generally, the present subject matter is directed to gas turbine engine accelerators having compound exit angles. More particularly, the present subject matter is directed to an accelerator that defines a radial direction and an axial direction and comprises an annular outer wall, an annular inner wall, and an annular channel defined therebetween having an outlet for egress of a cooling fluid from the channel. The outlet is angled such that an exit angle of the cooling fluid is nonzero with respect to the radial direction and is nonzero with respect to the axial direction. Further, at least one of the inner wall and the outer wall may have a first length defined at a first non-zero angle with respect to the axial direction and a second length defined at a second non-zero angle with respect to the axial direction. In exemplary embodiments, the outlet is disposed immediately upstream of a first turbine rotor blade stage to direct the cooling fluid to the first turbine rotor blade stage. Referring now to the drawings, wherein identical numerals indicate the same elements throughout the figures,FIG.1is a schematic cross-sectional view of a gas turbine engine in accordance with an exemplary embodiment of the present disclosure. More particularly, for the embodiment ofFIG.1, the gas turbine engine is a high-bypass turbofan jet engine10, referred to herein as “turbofan engine10.” As shown inFIG.1, the turbofan engine10defines an axial direction A (extending parallel to a longitudinal centerline12provided for reference), a circumferential direction C (extending about the longitudinal centerline12and the axial direction A), and a radial direction R. In general, the turbofan10includes a fan section14and a core turbine engine16disposed downstream from the fan section14. The exemplary core turbine engine16depicted generally includes a substantially tubular outer casing18that defines an annular inlet20. The outer casing18encases, in serial flow relationship, a compressor section including a booster or low pressure (LP) compressor22and a high pressure (HP) compressor24; a combustion section26; a turbine section including a high pressure (HP) turbine28and a low pressure (LP) turbine30; and a jet exhaust nozzle section32. A high pressure (HP) shaft or spool34drivingly connects the HP turbine28to the HP compressor24. A low pressure (LP) shaft or spool36drivingly connects the LP turbine30to the LP compressor22. For the depicted embodiment, fan section14includes a fan38having a plurality of fan blades40coupled to a disk or hub42in a spaced apart manner. As depicted, fan blades40extend outward from disk42generally along the radial direction R. The fan blades40and disk42are together rotatable about the longitudinal centerline12by LP shaft36. In some embodiments, a power gear box having a plurality of gears may be included for stepping down the rotational speed of the LP shaft36to a more efficient rotational fan speed. Referring still to the exemplary embodiment ofFIG.1, the disk42is covered by a rotatable front nacelle48aerodynamically contoured to promote an airflow through the plurality of fan blades40. Additionally, the exemplary fan section14includes an annular fan casing or outer nacelle50that circumferentially surrounds the fan38and/or at least a portion of the core turbine engine16. It should be appreciated that fan case (nacelle)50may be configured to be supported relative to the core turbine engine16by a plurality of circumferentially-spaced outlet guide vanes52. Moreover, a downstream section54of the fan case50may extend over an outer portion of the core turbine engine16so as to define a bypass airflow passage56therebetween. During operation of the turbofan engine10, a volume of air58enters turbofan10through an associated inlet60of the fan case50and/or fan section14. As the volume of air58passes across fan blades40, a first portion of the air58as indicated by arrows62is directed or routed into the bypass airflow passage56and a second portion of the air58as indicated by arrows64is directed or routed into the LP compressor22. The ratio between the first portion of air62and the second portion of air64is commonly known as a bypass ratio. The pressure of the second portion of air64is then increased as it is routed through the compressor section and into the combustion section26, where it is mixed with fuel and burned to provide combustion gases66. More particularly, the compressor section includes the LP compressor22and the HP compressor24that each may comprise a plurality of compressor stages80, with each stage80including both an annular array or circumferential row of stationary compressor vanes82(also referred to as compressor stator vanes82) and an annular array or circumferential row of rotating compressor blades84(also referred to as compressor rotor blades84) positioned immediately downstream of the compressor vanes82. The plurality of compressor blades84in the LP compressor22are coupled to the LP shaft or spool36, and the plurality of compressor blades in the HP compressor24are coupled to the HP shaft or spool34. The plurality of compressor vanes82in the LP compressor22are coupled to a compressor casing, and the plurality of compressor vanes82in the HP compressor24are coupled to a compressor casing; at least a portion of the HP compressor vanes82are coupled to compressor casing90. In some embodiments, the compressor casing90may extend through both the LP compressor22and the HP compressor24and support all of the compressor vanes82. In other embodiments, the compressor casing90supports only a portion of the compressor vanes82and may support only a portion of the compressor vanes82in the HP compressor24. As previously described, as the second portion of air64passes through the sequential stages of compressor vanes82and blades84, the volume of air64is pressurized, i.e., the pressure of the air64is increased prior to combustion with fuel in the combustion section26to form the combustion gases66. The combustion gases66are routed through the HP turbine28where a portion of thermal and/or kinetic energy from the combustion gases66is extracted via sequential stages of HP turbine stator vanes68that are coupled to the outer casing18and HP turbine rotor blades70that are coupled to the HP shaft or spool34, thus causing the HP shaft or spool34to rotate, thereby supporting operation of the HP compressor24. The combustion gases66are then routed through the LP turbine30where a second portion of thermal and kinetic energy is extracted from the combustion gases66via sequential stages of LP turbine stator vanes72that are coupled to the outer casing18and LP turbine rotor blades74that are coupled to the LP shaft or spool36, thus causing the LP shaft or spool36to rotate, thereby supporting operation of the LP compressor22and/or rotation of the fan38. The combustion gases66are subsequently routed through the jet exhaust nozzle section32of the core turbine engine16to provide propulsive thrust. Simultaneously, the pressure of the first portion of air62is substantially increased as the first portion of air62is routed through the bypass airflow passage56before it is exhausted from a fan nozzle exhaust section76of the turbofan10, also providing propulsive thrust. The HP turbine28, the LP turbine30, and the jet exhaust nozzle section32at least partially define a hot gas path78for routing the combustion gases66through the core turbine engine16. Although the gas turbine engine ofFIG.1is depicted in a turboshaft configuration, it will be appreciated that the teachings of the present disclosure can apply to other types of turbine engines, turbomachines more generally, and other shaft systems. For example, the turbine engine may be another suitable type of gas turbine engine, such as e.g., a turboprop, turbojet, turbofan, aeroderivatives, etc. The present disclosure may also apply to other types of turbomachinery, such as e.g., steam turbine engines. FIG.2provides a schematic cross-sectional view of a portion of the combustion section26and the HP turbine28. More particularly,FIG.2illustrates an accelerator100disposed in a gas turbine engine, such as the core turbine engine16of the turbofan10. The gas turbine engine16includes a combustor26, a first turbine stator vane stage28A of the HP turbine28disposed immediately downstream of the combustor26, and a first turbine rotor blade stage28B of the HP turbine28disposed immediately downstream of the first turbine stator vane stage28A. The first turbine stator vane stage28A comprises an annular array of stator vane airfoils68, and the first turbine rotor blade stage28B comprises an annular array of rotor blade airfoils70. The rotor blade airfoils70are coupled to a rotatable shaft, i.e., the HP shaft or spool34. The accelerator100circumferentially surrounds the shaft34. The accelerator100comprises an annular channel102for receipt of a cooling fluid F. The channel includes an inlet104for receipt of the cooling fluid F, and an outlet106defining a compound exit angle for the cooling fluid F. The outlet106is disposed immediately upstream of the first turbine rotor blade stage28B to direct the cooling fluid F to the first turbine rotor blade stage28B. FIGS.3,4A and4Billustrate the accelerator100in greater detail. As shown inFIGS.3and4A, the accelerator100defines a radial direction R and an axial direction A. The accelerator100comprises an annular outer wall108and an annular inner wall110that define the annular channel102therebetween. As described above, the channel102has inlet104for ingress of the cooling fluid F into the channel102and outlet106for egress of the cooling fluid F from the channel102. The accelerator100has an overall annular shape and, as such, encircles the rotor34such that the rotor34passes therethrough. An axial centerline of the accelerator100may be aligned generally along a longitudinal centerline of the rotor34(which may be disposed along the longitudinal centerline12of the engine10). Further, a plurality of vanes112are disposed within the channel102. Each vane112extends from the outer wall108to the inner wall110, and each vane112is disposed adjacent the outlet106. Moreover, each vane112has a shape configured to induce a tangential flow of the cooling fluid F upon egress from the outlet106. That is, the vanes112are shaped to turn the flow of the cooling fluid F tangential to the rotor blades70of the first turbine rotor blade stage28B. As described in greater detail herein, the outer wall108, the inner wall110, and the plurality of vanes112are integrally formed as a single monolithic component, e.g., using an additive manufacturing process. As previously described, the outlet106defines a compound exit angle for the cooling fluid F. For instance, as shown inFIGS.4A and4Bcollectively, the outlet106is angled such that an exit angle α of the cooling fluid F is nonzero with respect to the radial direction R and is nonzero with respect to the axial direction A. That is, the exit angle α of the cooling fluid F is angled with respect to both the radial direction R and the axial direction A such that the exit angle α is nonzero when measured with respect to the radial direction R (αradial) and is nonzero when measured with respect to the axial direction A (αaxial). The cooling fluid channel having a compound exit angle α of the exemplary embodiments described herein may have a greater portion of its length extending along the radial direction R than typical designs, which usually extend substantially along an axial direction such that the exiting flow is substantially axial. More particularly, as illustrated in the exemplary embodiment ofFIG.4A, the inner wall110is angled with respect to the axial direction A, as well as the radial direction R. That is, the inner wall110is defined at a nonzero angle with respect to both the axial direction A and the radial direction R. As shown inFIG.4A, the channel102comprises a mid-portion114located between the inlet104and the outlet106. In some embodiments, the mid-portion114may be approximately halfway between the inlet104and the outlet106along a length of the channel102measured from the inlet104to the outlet106. In other embodiments, the mid-portion114may be closer to the inlet104or closer to the outlet106rather than the approximate halfway location between the inlet104and the outlet106. In the depicted embodiment, the inner wall110is defined at a first nonzero angle β with respect to the axial direction A over a first length L1, and the inner wall110is defined at a second nonzero angle γ with respect to the axial direction over a second length L2. The first length L1extends from the inlet104to the mid-portion114, and the second length L2extends from the mid-portion114to the outlet106. As shown inFIG.4, the first nonzero angle β is larger than the second nonzero angle γ, i.e., β>γ. In other embodiments, however, the second nonzero angle γ may be larger than the first nonzero angle β such that β<γ. Further, the first and second lengths L1, L2may extend over other portions of the inner wall110, although one of the first length L1and second length L2is defined adjacent the outlet106to provide the exiting cooling fluid F at an angle with respect to the radial and axial directions R, A. In the illustrated embodiment, unlike the inner wall110, the outer wall108is not defined at two different nonzero angles with respect to the axial direction A. It will be appreciated that, in other exemplary embodiments, the outer wall108also may be defined at two or more nonzero angles with respect to the axial direction A. Further, the inner wall110may be defined at more than two nonzero angles with respect to the axial direction A. In some embodiments, the outer wall108may be defined at multiple nonzero angles with respect to the axial direction A while the inner wall110is not defined at multiple nonzero angles with respect to the axial direction A (e.g., may be defined at only one nonzero angle with respect to the axial direction A). In still other embodiments, one of the outer wall108and the inner wall110(or a portion thereof) may be substantially parallel to the axial direction A while the other of the outer wall108and the inner wall110is defined at multiple nonzero angles with respect to the axial direction A. It will be appreciated that the multiple nonzero angles of the outer wall108and/or inner wall110help define the compound exit angle of the cooling fluid F. As further depicted inFIGS.4A and4Bcollectively, the channel outlet106is angled radially inward such that the channel inlet104is disposed radially outward of the outlet106. More particularly, the outlet106is angled such that the outlet106directs the flow of the cooling fluid F radially inward with respect to the first turbine rotor blade stage28B. As such, the cooling fluid F is directed toward the rotor34(i.e., the HP shaft or spool34in the illustrated exemplary embodiment) to help cool the rotor34. By angling the flow of the cooling fluid F as it exits the channel102, as well as using the vanes112to direct the cooling fluid flow tangential to the rotor34, the cooling fluid flow may be sped up to the tangential speed of the rotor34and rotor blades70. In exemplary embodiments, the channel102of the accelerator100may be defined such that, upon exiting the channel102, the flow of the cooling fluid F is going approximately the same speed in approximately the same direction as the rotor34and rotor blades70, which can help increase cooling efficiency by reducing relative stagnation between the cooling fluid flow and the rotor34and rotor blades70. Keeping withFIG.4A, the channel102defines a width W from the inner wall110to the outer wall108, and the width W varies along the channel102from the inlet104to the outlet106. In the depicted embodiment, the width W of the channel102decreases both from the inlet104to the mid-portion114and from the mid-portion114to the outlet106such that the width W at the inlet104is larger than the width W at the outlet106, i.e., Winlet>Woutlet. Narrowing the channel102from the inlet104to the outlet106helps speed up the flow of the cooling fluid F to the tangential speed of the rotor34and rotor blades70. As further illustrated inFIGS.3and4, an annular flange116extends radially outward from the outer wall108. In exemplary embodiments, the flange116is integrally formed with the outer wall108, e.g., such that the outer wall108, the inner wall110, the plurality of vanes112, and the flange116are integrally formed as a single monolithic component. Moreover, the flange116defines a plurality of apertures118therein. The apertures118are defined about a circumference of the flange116such that the apertures118are spaced apart from one another about the circumference of the flange116. As shown inFIG.2, in exemplary embodiments, the apertures118are configured to receive an attachment mechanism, such as a bolt or other suitable fastener, e.g., to secure the accelerator100in position within the core turbine engine16. In the depicted exemplary embodiment, the flange116is substantially parallel to the radial direction R. Further, the flange116is disposed radially outward from the outlet106such that the flange116and the outlet106define an aft end120of the accelerator100. More particularly, the flange116and the outlet106may be generally aligned with one another along the radial direction R and may define the aftmost portions of the accelerator100. Additionally, a connecting portion122, or simply connector122, may be defined between an inlet end124of the outer wall108and the flange116. In the exemplary embodiment illustrated inFIGS.4A and4Bcollectively, the connector122is substantially parallel to the axial direction A. A semi-circular fillet125is defined between the inlet end124of the outer wall108and the connector122. Further, the connector122defines an inner surface126against which a seal, such as an abradable seal128, may be disposed, e.g., to provide a fluid seal between the accelerator100and the first turbine rotor blade stage28B. Also in the illustrated embodiment, an inner wall flange130extending axially forward from the inner wall110. The inner wall flange130extends from the inner wall110adjacent the mid-portion114such that a fillet132is defined between the inner wall110and the inner wall flange130at the mid-portion114. Moreover, the inner wall flange130defines an inner surface134against which a seal, such as an abradable seal128, may be disposed, e.g., to provide a fluid seal between the accelerator100and the first turbine rotor blade stage28B. The accelerator100may define other flanges as well. For example, as shown most clearly inFIG.4A, a flange136may be defined at an inlet end138of the inner wall110. In the depicted embodiment, the flange136extends substantially along the radial direction R. Similarly, a flange140may be defined at an outlet end142of the outer wall108. In the illustrated embodiment, the flange140extends generally along the radial direction R but is slightly angled with respect to the radial direction R. The flanges136,140may help align the accelerator100with other engine components, may provide an area for coupling the accelerator100to other engine components, etc. Accordingly, other orientations of the flanges136,140than the illustrated orientations also may be suitable. In general, the exemplary embodiments of the accelerator100described herein may be manufactured or formed using any suitable process. However, in accordance with several aspects of the present subject matter, the accelerator100may be formed using an additive-manufacturing process, such as a 3D printing process. The use of such a process may allow the outer wall108, the inner wall110, and the vanes112of the accelerator100to be formed integrally, as a single monolithic component, or as any suitable number of sub-components. In particular, the manufacturing process may allow the outer wall108, the inner wall110, and the vanes112to be integrally formed and include a variety of features not possible when using prior manufacturing methods. For example, the additive manufacturing methods described herein enable the manufacture of cooling channels and accelerators having any suitable size and shape with one or more configurations of channel walls, channel widths, and channel exit angles, as well as other features which were not possible using prior manufacturing methods, such as smaller features including smaller fillets and smaller holes or apertures, as well as smaller fillet radii. Some of these novel features are described herein. As used herein, the terms “additively manufactured” or “additive manufacturing techniques or processes” refer generally to manufacturing processes wherein successive layers of material(s) are provided on each other to “build-up,” layer-by-layer, a three-dimensional component. The successive layers generally fuse together to form a monolithic component which may have a variety of integral sub-components. Although additive manufacturing technology is described herein as enabling fabrication of complex objects by building objects point-by-point, layer-by-layer, typically in a vertical direction, other methods of fabrication are possible and within the scope of the present subject matter. For instance, although the discussion herein refers to the addition of material to form successive layers, one skilled in the art will appreciate that the methods and structures disclosed herein may be practiced with any additive manufacturing technique or manufacturing technology. For example, embodiments of the present invention may use layer-additive processes, layer-subtractive processes, or hybrid processes. Suitable additive manufacturing techniques in accordance with the present disclosure include, for example, Fused Deposition Modeling (FDM), Selective Laser Sintering (SLS), 3D printing such as by inkjets and laserjets, Sterolithography (SLA), Direct Selective Laser Sintering (DSLS), Electron Beam Sintering (EBS), Electron Beam Melting (EBM), Laser Engineered Net Shaping (LENS), Laser Net Shape Manufacturing (LNSM), Direct Metal Deposition (DMD), Digital Light Processing (DLP), Direct Selective Laser Melting (DSLM), Selective Laser Melting (SLM), Direct Metal Laser Melting (DMLM), and other known processes. In addition to using a direct metal laser sintering (DMLS) or direct metal laser melting (DMLM) process where an energy source is used to selectively sinter or melt portions of a layer of powder, it should be appreciated that according to alternative embodiments, the additive manufacturing process may be a “binder jetting” process. In this regard, binder jetting involves successively depositing layers of additive powder in a similar manner as described above. However, instead of using an energy source to generate an energy beam to selectively melt or fuse the additive powders, binder jetting involves selectively depositing a liquid binding agent onto each layer of powder. The liquid binding agent may be, for example, a photo-curable polymer or another liquid bonding agent. Other suitable additive manufacturing methods and variants are intended to be within the scope of the present subject matter. The additive manufacturing processes described herein may be used for forming components using any suitable material. For example, the material may be plastic, metal, concrete, ceramic, polymer, epoxy, photopolymer resin, or any other suitable material that may be in solid, liquid, powder, sheet material, wire, or any other suitable form. More specifically, according to exemplary embodiments of the present subject matter, the additively manufactured components described herein may be formed in part, in whole, or in some combination of materials including but not limited to pure metals, nickel alloys, chrome alloys, titanium, titanium alloys, magnesium, magnesium alloys, aluminum, aluminum alloys, iron, iron alloys, stainless steel, and nickel or cobalt based superalloys (e.g., those available under the name Inconel® available from Special Metals Corporation). These materials are examples of materials suitable for use in the additive manufacturing processes described herein, and may be generally referred to as “additive materials.” In addition, one skilled in the art will appreciate that a variety of materials and methods for bonding those materials may be used and are contemplated as within the scope of the present disclosure. As used herein, references to “fusing” may refer to any suitable process for creating a bonded layer of any of the above materials. For instance, if an object is made from polymer, fusing may refer to creating a thermoset bond between polymer materials. If the object is epoxy, the bond may be formed by a crosslinking process. If the material is ceramic, the bond may be formed by a sintering process. If the material is powdered metal, the bond may be formed by a melting or sintering process. One skilled in the art will appreciate that other methods of fusing materials to make a component by additive manufacturing are possible, and the presently disclosed subject matter may be practiced with those methods. Moreover, the additive manufacturing process disclosed herein allows a single component to be formed from multiple materials. Thus, the components described herein may be formed from any suitable mixtures of the above materials. For example, a component may include multiple layers, segments, or parts that are formed using different materials, processes, and/or on different additive manufacturing machines. In this manner, components may be constructed that have different materials and material properties for meeting the demands of any particular application. Further, although additive manufacturing processes for forming the components described herein are described in detail, it should be appreciated that in alternate embodiments, all or a portion of these components may be formed via casting, machining, and/or any other suitable manufacturing process. Indeed, any suitable combination of materials and manufacturing methods may be used to form these components. An exemplary additive manufacturing process will now be described. Additive manufacturing processes fabricate components using three-dimensional (3D) information, for example, a three-dimensional computer model, of the component. Accordingly, a three-dimensional design model of the component may be defined prior to manufacturing. In this regard, a model or prototype of the component may be scanned to determine the three-dimensional information of the component. As another example, a model of the component may be constructed using a suitable computer aided design (CAD) program to define the three-dimensional design model of the component. The design model may include 3D numeric coordinates of the entire configuration of the component including both external and internal surfaces of the component. For example, the design model may define the body, the surface, and/or internal passageways such as openings, support structures, etc. In one exemplary embodiment, the three-dimensional design model is converted into a plurality of slices or segments, e.g., along a central (e.g., vertical) axis of the component or any other suitable axis. Each slice may define a thin cross section of the component for a predetermined height of the slice. The plurality of successive cross-sectional slices together form the 3D component. The component is then “built-up” slice-by-slice, or layer-by-layer, until finished. In this manner, the components described herein may be fabricated using the additive process, or more specifically each layer is successively formed, e.g., by fusing or polymerizing a plastic using laser energy or heat or by sintering or melting metal powder. For instance, a particular type of additive manufacturing process may use an energy beam, for example, an electron beam or electromagnetic radiation such as a laser beam, to sinter or melt a powder material. Any suitable laser and laser parameters may be used, including considerations with respect to power, laser beam spot size, and scanning velocity. The build material may be formed by any suitable powder or material selected for enhanced strength, durability, and useful life, particularly at high temperatures. Each successive layer may be, for example, between about 10 μm and 200 μm, although the thickness may be selected based on any number of parameters and may be any suitable size according to alternative embodiments. Therefore, utilizing the additive formation methods described above, the components described herein may have cross sections as thin as one thickness of an associated powder layer, e.g., 10 μm, utilized during the additive formation process. In addition, utilizing an additive process, the surface finish and features of the components may vary as need depending on the application. For instance, the surface finish may be adjusted (e.g., made smoother or rougher) by selecting appropriate laser scan parameters (e.g., laser power, scan speed, laser focal spot size, etc.) during the additive process, especially in the periphery of a cross-sectional layer that corresponds to the part surface. For example, a rougher finish may be achieved by increasing laser scan speed or decreasing the size of the melt pool formed, and a smoother finish may be achieved by decreasing laser scan speed or increasing the size of the melt pool formed. The scanning pattern and/or laser power can also be changed to change the surface finish in a selected area. Notably, in exemplary embodiments, several features of the components described herein were previously not possible due to manufacturing restraints. However, the present inventors have advantageously utilized current advances in additive manufacturing techniques to develop exemplary embodiments of such components generally in accordance with the present disclosure. While the present disclosure is not limited to the use of additive manufacturing to form these components generally, additive manufacturing does provide a variety of manufacturing advantages, including ease of manufacturing, reduced cost, greater accuracy, etc. In this regard, utilizing additive manufacturing methods, even multi-part components may be formed as a single piece of continuous metal, and may thus include fewer sub-components and/or joints compared to prior designs. The integral formation of these multi-part components through additive manufacturing may advantageously improve the overall assembly process. For instance, the integral formation reduces the number of separate parts that must be assembled, thus reducing associated time and overall assembly costs. Additionally, existing issues with, for example, leakage, joint quality between separate parts, and overall performance may advantageously be reduced. Also, the additive manufacturing methods described above enable much more complex and intricate shapes and contours of the components described herein. For example, such components may include thin additively manufactured layers, unique pseudo flange geometries, tailored cooling cavity sizes and shapes, and/or tailored cooling fluid passageway numbers, shapes, and paths. As a specific example, using additive manufacturing methods such as those described herein, one or more case segments of a compressor case may be formed with uniquely shaped outer surface raised portions that define one or more cavities and/or one or more passageways therein. Further, the cross-sectional shape, number, and/or relative position of each cavity and passageway within a raised portion may vary among the raised portions of a case segment. In addition, although additive manufacturing enables manufacture of single monolithic components as describe herein from a single material, the additive manufacturing process also enables the manufacture of a single component having different materials such that different portions of the component may exhibit different performance characteristics. The successive, additive nature of the manufacturing process enables the construction of these novel features. As a result, the components described herein may exhibit improved performance and reliability. It should be appreciated that the accelerator100, having a channel102with a compound exit angle for a fluid flowing through the channel, described herein is only for the purpose of explaining aspects of the present subject matter. For example, the accelerator100is used herein to describe exemplary configurations, constructions, and methods of manufacturing the accelerator100. It should be appreciated that the additive manufacturing techniques discussed herein may be used to manufacture other casings or similar components for use in any suitable device, for any suitable purpose, and in any suitable industry. Thus, the exemplary components and methods described herein are used only to illustrate exemplary aspects of the present subject matter and are not intended to limit the scope of the present disclosure in any manner. Now that the construction and configuration of the accelerator100according to exemplary embodiments of the present subject matter have been presented, an exemplary method500is provided for forming an accelerator according to an exemplary embodiment of the present subject matter. Method500can be used by a manufacturer to form an outer wall108and an inner wall110defining a channel102therebetween, along with the various other features described herein, and, thus, form the accelerator100or any other suitable accelerator. It should be appreciated that the exemplary method500is discussed herein only to describe exemplary aspects of the present subject matter and is not intended to be limiting. Referring now toFIG.5, method500includes, at block502, depositing a layer of additive material on a bed of an additive manufacturing machine. Method500further includes, at block504, selectively directing energy from an energy source onto the layer of additive material to fuse a portion of the additive material and form an accelerator. For example, the accelerator may be the accelerator100formed for the HP turbine28of the core turbine engine16of the turbofan jet engine10described herein. More particularly, as described herein, the accelerator100may comprise an annular outer wall108, an annular inner wall110, an annular channel102defined between the outer wall108and the inner wall110, and one or more vanes112disposed within the channel102. The channel102may include an inlet104for ingress of a cooling fluid F into the channel102and an outlet106for egress of the cooling fluid F from the channel102. The one or more vanes112may each extend from the outer wall108to the inner wall110at a location adjacent the channel outlet106. Moreover, the channel outlet106may be angled such that an exit angle α of the cooling fluid F is nonzero with respect to both a radial direction R and an axial direction A defined by the accelerator100. Using the additive manufacturing process of method500, the outer wall108, the inner wall110, and the vane112are integrally formed as a single monolithic component. It will be appreciated that the accelerator100formed by the additive process of method500also may include any or all of the additional features described herein, such as the flange116having apertures118defined therein, the connector122, and the flanges136,140. Accordingly, the present subject matter is directed to assemblies, systems, and methods for providing cooling flow to rotor blade stages. More particularly, the present subject matter is directed to an accelerator that introduces a tangential velocity component to cooling air, e.g., turbine stage one cooling air, that is larger than the rotor speed to minimize parasitic power losses in the rotor cavity and pressure losses in the cooling supply circuit, e.g., the stage one blade cooling supply circuit. Further, the accelerator described herein provides high efficiency pumping characteristics to minimize the temperature of blade cooling flow. Moreover, as described herein, the accelerator may be additively manufactured to enable optimized vane geometry and aerodynamic performance beyond traditional casting technology. Still further, the accelerator described herein includes a compound exit angle for the cooling fluid, which enables smaller axial packaging of the engine while maintaining rotor clearances, as well as close coupling between the accelerator and the rotor blades while maintaining rotor clearances. What is more, an accelerator as describe herein reduces exit velocity drop of the arc between the accelerator exit and cooling plate entry, which increases close coupling between the accelerator and rotor blade stage while decreasing cooling fluid jet travel length and velocity degradation, thereby improving cooling system performance. Other benefits and advantages of the present subject matter may be realized as well. Further aspects of the invention are provided by the subject matter of the following clauses: An accelerator for a gas turbine engine, the accelerator defining a radial direction and an axial direction, the accelerator comprising an annular outer wall; an annular inner wall; an annular channel defined between the outer wall and the inner wall, the channel having an inlet for ingress of a cooling fluid into the channel and an outlet for egress of the cooling fluid from the channel; and a plurality of vanes disposed within the channel, each vane of the plurality of vanes extending from the outer wall to the inner wall adjacent the outlet, wherein the outlet is angled such that an exit angle of the cooling fluid is nonzero with respect to the radial direction and is nonzero with respect to the axial direction. The accelerator of any preceding clause, wherein the outer wall, the inner wall, and the plurality of vanes are integrally formed as a single monolithic component. The accelerator of any preceding clause, wherein the outlet is angled radially inward such that the inlet is disposed radially outward of the outlet. The accelerator of any preceding clause, wherein each vane of the plurality of vanes has a shape configured to induce a tangential flow of the cooling fluid upon egress from the outlet. The accelerator of any preceding clause, wherein the channel defines a width from the inner wall to the outer wall, and wherein the width varies along the channel from the inlet to the outlet. The accelerator of any preceding clause, wherein the channel comprises a mid-portion located between the inlet and the outlet, and wherein the width of the channel decreases both from the inlet to the mid-portion and from the mid-portion to the outlet such that the width at the inlet is larger than the width at the outlet. The accelerator of any preceding clause, wherein the inner wall is angled with respect to the axial direction. The accelerator of any preceding clause, wherein the channel comprises a mid-portion located between the inlet and the outlet, wherein the inner wall is defined at a first nonzero angle with respect to the axial direction over a first length, and wherein the inner wall is defined at a second nonzero angle with respect to the axial direction over a second length, the first length defined from the inlet to the mid-portion and the second length defined from the mid-portion to the outlet. The accelerator of any preceding clause, wherein the first nonzero angle is larger than the second nonzero angle. The accelerator of any preceding clause, further comprising an annular flange extending radially outward from the outer wall. The accelerator of any preceding clause, wherein the flange defines a plurality of apertures therein, the plurality of apertures spaced apart from one another about a circumference of the flange. The accelerator of any preceding clause, wherein the flange is substantially parallel to the radial direction. The accelerator of any preceding clause, wherein the outer wall, the inner wall, the plurality of vanes, and the flange are integrally formed as a single monolithic component. The accelerator of any preceding clause, further comprising a connector defined between an inlet end of the outer wall and the flange, wherein the connector is substantially parallel to the axial direction. The accelerator of any preceding clause, wherein the outer wall, the inner wall, the plurality of vanes, the flange, and the connector are integrally formed as a single monolithic component. The accelerator of any preceding clause, further comprising an inner wall flange extending axially forward from the inner wall, wherein the channel comprises a mid-portion located between the inlet and the outlet, and wherein the inner wall flange extends from the inner wall adjacent the mid-portion such that a fillet is defined between the inner wall and the inner wall flange at the mid-portion. The accelerator of any preceding clause, wherein the outer wall, the inner wall, the plurality of vanes, and the inner wall flange are integrally formed as a single monolithic component. The accelerator of any preceding clause, wherein the outer wall, the inner wall, the plurality of vanes, the flange defining a plurality of apertures therein, the connector, and the inner wall flange are integrally formed as a single monolithic component. The accelerator of any preceding clause, further comprising a second inner wall flange defined at an inlet end of the inner wall, the second inner wall flange extending substantially along the radial direction. The accelerator of any preceding clause, wherein the outer wall, the inner wall, the plurality of vanes, and the second inner wall flange are integrally formed as a single monolithic component. The accelerator of any preceding clause, wherein the outer wall, the inner wall, the plurality of vanes, the flange defining a plurality of apertures therein, the connector, the inner wall flange, and the second inner wall flange are integrally formed as a single monolithic component. The accelerator of any preceding clause, further comprising an outer wall flange defined at an outlet end of the outer wall, the outer wall flange extending generally along the radial direction. The accelerator of any preceding clause, wherein the outer wall flange is slightly angled with respect to the radial direction. The accelerator of any preceding clause, wherein the outer wall, the inner wall, the plurality of vanes, and the outer wall flange are integrally formed as a single monolithic component. The accelerator of any preceding clause, wherein the outer wall, the inner wall, the plurality of vanes, the flange defining a plurality of apertures therein, the connector, the inner wall flange, the second inner wall flange, and the outer wall flange are integrally formed as a single monolithic component. The accelerator of any preceding clause, wherein the accelerator comprises a plurality of layers formed by depositing a layer of additive material on a bed of an additive manufacturing machine; and selectively directing energy from an energy source onto the layer of additive material to fuse a portion of the additive material, wherein the outer wall, the inner wall, and the plurality of vanes are integrally formed as a single monolithic component. The accelerator of any preceding clause, wherein the outlet defines a compound exit angle for the cooling fluid. A method of manufacturing an accelerator for a gas turbine engine, the method comprising depositing a layer of additive material on a bed of an additive manufacturing machine; and selectively directing energy from an energy source onto the layer of additive material to fuse a portion of the additive material and form the accelerator, the accelerator comprising an annular outer wall, an annular inner wall, an annular channel defined between the outer wall and the inner wall, and a vane disposed within the channel, wherein the channel includes an inlet for ingress of a cooling fluid into the channel and an outlet for egress of the cooling fluid from the channel, wherein the vane extends from the outer wall to the inner wall adjacent the outlet, wherein the outlet is angled such that an exit angle of the cooling fluid has a nonzero radial portion and a nonzero axial portion, and wherein the outer wall, the inner wall, and the vane are integrally formed as a single monolithic component. The method of any preceding clause, wherein the accelerator further comprises an annular flange extending radially outward from the outer wall, wherein the flange is integrally formed with the outer wall. The method of any preceding clause, wherein the flange defines a plurality of apertures therein, the plurality of apertures defined about a circumference of the flange. The method of any preceding clause, wherein the flange is disposed radially outward from the outlet such that the flange and the outlet define an aft end of the accelerator. A gas turbine engine, comprising a combustor; a first turbine stator vane stage disposed immediately downstream of the combustor, the first turbine stator vane stage comprising an annular array of stator vane airfoils; a first turbine rotor blade stage disposed immediately downstream of the first turbine stator vane stage, the first turbine rotor blade stage comprising an annular array of rotor blade airfoils coupled to a rotatable shaft; and an accelerator circumferentially surrounding the shaft, the accelerator comprising an annular channel for receipt of a cooling fluid, the channel including an outlet defining a compound exit angle for the cooling fluid, wherein the outlet of the accelerator is disposed immediately upstream of the first turbine rotor blade stage to direct the cooling fluid to the first turbine rotor blade stage. This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. | 50,269 |
11859551 | DETAILED DESCRIPTION Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, an illustrative view of an embodiment of a fuel system in accordance with the disclosure is shown inFIG.1and is designated generally by reference character100. Other embodiments and/or aspects of this disclosure are shown inFIG.2. In accordance with at least one aspect of this disclosure, as shown inFIG.1, a fuel system100can include a selection and shutoff valve (SSOV)101configured to allow a primary flow having a primary flow pressure P3to pass therethrough in a first state (e.g., a normal operation) such that the primary flow can travel to an output line103. As shown inFIG.2, the SSOV101can also be configured to shut off the primary flow in a second state (e.g., a shutoff/secondary operation) to prevent the primary flow from travelling to the output line. In the second state, the SSOV101can be configured to allow a secondary flow from a secondary flow source105(e.g., a secondary pump used to create hydraulic pressure for actuators) to pass therethrough such that the secondary flow can travel to the output line103. As shown, the SSOV101can be a spool valve that has a spool102that slides linearly between the first state and the second state. A seal can be installed in the SSOV101to stop leakage during shutdown (e.g., in the second position as shown inFIG.2). Any other suitable valve type is contemplated herein. In the first state, the SSOV101can be configured to communicate a primary input101aof the SSOV101to a primary output101bof the SSOV101that is in fluid communication with the output line103(e.g., indirectly through a minimum pressure valve109, directly, or otherwise). In the first state, the SSOV101can be configured to communicate a secondary flow source input101cof the SSOV101to a secondary flow destination output101dof the SSOV101to allow the secondary flow to flow from the secondary flow source105to the secondary flow destination107. In the second state, the SSOV101can be configured to communicate the secondary flow source input101cto the primary output101bor to a secondary output101e(e.g., as shown inFIGS.1and2) in fluid communication with the output line103. In the second state, the SSOV101can be configured to communicate a low pressure port101fof the SSOV101to a bypass valve port101gof the SSOV101in fluid communication with a bypass valve111, e.g., a windmill bypass valve (WMBV), via a bypass line113to communicate a low pressure P1to the WMBV111. In the first state, the SSOV101can be configured to prevent fluid communication between the low pressure port101fand the bypass valve port101g. The primary input101acan be positioned to cause the primary flow to act on the SSOV101to bias the SSOV101toward the first position (e.g., as shown inFIG.1). The SSOV101can include a back pressure port101hconfigured to be in fluid communication with a back pressure line115such that a back pressure PSO acts on the SSOV101to bias the SSOV101toward the second position such that when the back pressure PSO exceeds a primary flow pressure P3of the primary flow, the SSOV101moves to the second position (e.g., as shown inFIG.2). In certain embodiments, the SSOV101can be biased to the second position via a biasing member117. The system100can include a metering valve (MV)119operatively connected to a pump121to receive a pump pressure P2and to the SSOV101to provide the primary pressure P3to the primary input port101aof the SSOV101. The MV119can be configured to reduce the pump pressure P2to the primary pressure P3as a function of its position (e.g., as appreciated by those having ordinary skill in the art) to meter flow to the SSOV101. The ratio between P1and P3can be controlled by the MV119as a function of position. As shown inFIGS.1and2, an MV119position all the way right can be a shut off position such that there is minimum or no primary flow, and max primary flow is the MV119position all the way left. As shown, in certain embodiments, the MV119can also be operatively connected to the back pressure port101hof the SSOV101via the back pressure line115. The MV119can be configured to prevent communication of the pump pressure P2to the back pressure line115in a first metering valve state (e.g., as shown inFIG.1). The MV119can also be configured to communicate the pump pressure P2to the back pressure line115in a second metering valve state (e.g., as shown inFIG.2) to cause the SSOV101to move to the second state. The back pressure line115can be connected to the low pressure P1via a first orifice123such that in the first metering valve state, the back pressure PSO stagnates at the low pressure P1, and in the second metering valve state, the back pressure PSO exceeds the primary flow pressure PS3(e.g., back pressure PSO equals pump pressure P2as shown inFIG.2). The first orifice123can be sized to ensure the pressure on the SSOV side is always higher than P1(and P3) in the second metering valve state and/or in the open state of the solenoid valve129, even though there is leakage through the orifice123, to cause the SSOV101to close. In a normal mode, the pressure would stagnate on the back pressure line115and reach P1through the first orifice123. In certain embodiments, the MV119can be controlled by an electrohydraulic servo valve125(EHSV) configured to control a position of the metering valve119between the first metering valve state and the second metering valve state. The EHSV125can be configured to receive the low pressure P1and the pump pressure P2, and to output a first control pressure PC1and a second control pressure PC2to opposing sides of the MV119to control a position of the MV119(e.g., as appreciated by those having ordinary skill in the art of EHSVs). The system100can include a bypass valve (WMBV)111. The WMBV111can be connected to the pump121to receive the pump pressure P2on a first side, and to the SSOV101on a second side via the bypass line113. The bypass line113can be connected to the pump121via a second orifice127such that in the first state of the SSOV, a bypass line pressure PBYP of the bypass line113stagnates at the pump pressure P2, and in the second state of the SSOV101, the bypass line pressure PBYP is lower than the pump pressure P2(e.g., PBYP being equal to P1) to cause the WMBV111to open on the first side of the WMBV111to allow the pump pressure P2to communicate with the low pressure P1to cause a bypass flow. For example, the low pressure P1can be a boost pump pressure and can be the upstream pressure provided to the pump121such that communicating the pump pressure P2to the low pressure P1causes circulation through the pump121. In certain embodiments, a solenoid valve129can be operatively connected to the pump121to receive the pump pressure P2and to the back pressure line115to communicate the pump pressure P2to the back pressure line115in an open state to cause the SSOV101to move to the second state, and to prevent the pump pressure P2from communicating with the back pressure line115in a closed state. The back pressure line115can be connected to the low pressure P1via a first orifice123such that in the closed state of the solenoid valve129(e.g., and the first metering valve state of the MV119), the back pressure stagnates at the low pressure, and in the open state (e.g., and/or the second metering valve state of the MV119), the back pressure PSO exceeds the primary flow pressure P3. In certain embodiments, e.g., as shown, the system100can include both the MV119and the solenoid valve129to provide redundancy (and different control paths) in control of the position of the SSOV101, and/or for any other suitable use. The system100can include a minimum pressure valve (MPV)109disposed downstream of the primary output101bof the SSOV101between the SSOV101and the output line103. In certain embodiments, e.g., as shown, the secondary output101ecan be in direct fluid communication with the output line103to bypass the MPV109in the second state of the SSOV101. Bypass around the MPV109can be optional, e.g., if the secondary flow source105is powerful enough to overcome MPV109. The MPV109can set a minimum delta pressure between primary pressure P3and low pressure P1(e.g., and thereby P2and P1) and can move toward closed position to increase pressure in system. A closure force value (and thus min pressure) can be defined by P1plus a biasing member value, for example. In certain embodiments, P3and/or Ps can always be higher than P1. An engine burner can be downstream of the output line103. Any other suitable components and/or arrangements for the fuel system are contemplated herein. In accordance with at least one aspect of this disclosure, a fuel system can be configured to direct a main pump flow to an engine in a first mode, and to direct a secondary flow source to the engine in a second mode. The fuel system can be any suitable embodiment of a fuel system disclosed herein, e.g., system100as described above, for example. In accordance with at least one aspect of this disclosure, a fuel system can include two independent electric shutoff systems (e.g., EHSV125controlling the MV119and the solenoid valve119) configured to control a selection and shutoff valve (SSOV)101. The two electric shutoff systems can be configured to control three valves (e.g., MV119, SSOV101, and WMBV111) to perform five functions. The fuel system can be any suitable embodiment of a fuel system disclosed herein, e.g., system100as described above, for example. In accordance with at least one aspect of this disclosure, an aircraft (not shown) can include a fuel system as disclosed herein, e.g., fuel system100as described above. Any other suitable aircraft systems are contemplated herein. Embodiments can include a fuel system that includes a main pump that delivers precisely the required flow at all operating conditions (e.g. through displacement control, speed control, or other). The pump can provide flow to a windmill bypass valve, a metering valve, and an EHSV. The system can include two independent electric shutoff systems. For example, an EHSV can command the metering valve to a position such that the pump pressure P2is exposed to the backend of the SSOV101, or a solenoid valve may open to allow the pump pressure P2at the backend of the SSOV101, thereby closing the SSOV101. When the SSOV is closed, low pressure P1can be exposed to the backend of the WMBV111, allowing it to open and bypass pump flow. With the SSOV101closed, a secondary flow source105can be ported to the output line103(e.g., connected to an engine burner). Embodiments can allow a no bypass metering valve system, secondary source selection, and a minimum number of EMIDs to control modes. Embodiments can provide pump protection when flow demand is not present and can provide min pressure regulation for low flow demands. Embodiments of a fuel system can safely accommodate a no-bypass pumping system through the use of two independent electric shutoff systems. Two EMIDs can be used to control three valves which perform five functions. Those having ordinary skill in the art understand that any numerical values disclosed herein can be exact values or can be values within a range. Further, any terms of approximation (e.g., “about”, “approximately”, “around”) used in this disclosure can mean the stated value within a range. For example, in certain embodiments, the range can be within (plus or minus) 20%, or within 10%, or within 5%, or within 2%, or within any other suitable percentage or number as appreciated by those having ordinary skill in the art (e.g., for known tolerance limits or error ranges). The articles “a”, “an”, and “the” as used herein and in the appended claims are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article unless the context clearly indicates otherwise. By way of example, “an element” means one element or more than one element. The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and/or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of” or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e., “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” Any suitable combination(s) of any disclosed embodiments and/or any suitable portion(s) thereof are contemplated herein as appreciated by those having ordinary skill in the art in view of this disclosure. The embodiments of the present disclosure, as described above and shown in the drawings, provide for improvement in the art to which they pertain. While the subject disclosure includes reference to certain embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the spirit and scope of the subject disclosure. | 14,520 |
11859552 | DETAILED DESCRIPTION FIG.1schematically illustrates a system20for an engine22. The engine22may be, for example, but not limited to, a gas turbine engine utilized for propulsion of an aircraft, a gas turbine engine utilized as an auxiliary power unit (APU) or other system. The system20may include a working fluid subsystem30, an electrical subsystem32and a control subsystem34. Although primarily described with respect to a fuel system in the illustrated embodiment, the working fluid subsystem30may alternatively utilize a fluid, such as for example, fuel, hydraulic, pneumatic, etc. The system20may alternatively or additionally include various components such as multiple fuel tanks, air-oil coolers, fuel driven actuators, fuel modules, solenoid valves, metering valves, shut-off valves, spill valves, and other filters. It should be appreciated that various other systems, subsystems and components particular to the working fluid may alternatively or additionally be provided and are contemplated as included by the system20. The fluid subsystem30includes a supply conduit36in communication with a low pressure boost pump40located within a fuel tank42. The supply conduit36may provide a fluid path through a filter system44, a high pressure pump46downstream of the filter system44, and a servo valve48downstream of the high pressure pump46. The servo valve48may be controlled by the control subsystem34to set a desired fuel flow to a combustor section50of the engine22through the supply conduit36. Downstream of the servo valve48, the working fluid, e.g., fuel, is communicated to the combustor section50of the engine22via solenoid valves,52A,52B that respectively control fuel into a primary manifold54with one or more injectors56A that provides start flow to the engine22and to a secondary manifold58with one or more injectors56B that provides the main flow to the engine22. A flow divider60may be utilized to facilitate flow control between the manifolds. Downstream of the high pressure pump46but upstream of the servo valve48, a recirculation conduit70communicates excess working fluid, e.g., fuel that is not communicated through the servo valve48to the combustor section50of the engine22is recirculated back to the fuel tank42. Fuel supply pumps are typically sized to provide fuel flow for peak power conditions with some additional margin. Under other operating conditions, the fuel supply pumps may supply significantly more fuel than required by the combustor section50and the excess flow is recirculated. Peak power is usually required on takeoff for turbofan main engines. For Auxiliary Power Units (APUs) peak power demand is typically during main engine start, or a combined operating condition where bleed air is required for an aircraft environmental control system or start system, and a generator load for electrical power. As an example, an APU at idle, 100% speed, no load, could operate at about 40 pounds per hour fuel consumption. Under max load, the APU may require up to 400 pounds per hour fuel consumption, an order of magnitude (10:1) more fuel. Gearbox driven mechanical pumps are always supplying that 400 pounds per hour fuel at 100% speed, independent of engine load conditions. Typically, a metering device (e.g., a servo valve) that is engine controller driven will only provide the fuel flow needed to maintain engine speed at 100% while providing the necessary load. So in the example of the APU at idle, 360 pounds per hour of fuel flow would be recirculated. At partial and full loads, some lesser quantity of fuel flow would be recirculated. All scenarios that represent some level of lost energy that may be recuperated. A pressure relief valve72may be located in the recirculation conduit70. Alternatively, the recirculation conduit70A may communicate excess working fluid upstream of the high pressure pump46(FIG.2). Downstream of the pressure relief valve72, but upstream of the fuel tank40, a permanent magnet generator module80is located within the recirculation conduit70and is thereby driven by the working fluid. Due to the change in engine load conditions and the resultant recirculation flow variation, the permanent magnet generator module80will provide variable output voltage such that a voltage regulator82or other system may complement the permanent magnet generator module80as part of the electrical subsystem32. The permanent magnet generator module80may provide the generated power to an electrical distribution system84such as a battery, distribution bus, engine auxiliaries requiring electrical power, or other such system. Alternatively, or in addition, the power may be routed through transformers, rectifiers or inverters to change the voltage or type of current. Individual components and systems may be powered from the bus with circuit protection in the form of a circuit breaker. The battery system may be used for engine start and as an emergency source of power in the event of a generation or distribution system failure. The electrical distribution system84may also be utilized with a hybrid electric engine system. The generated power may be distributed, stored, and/or controlled through the control subsystem34. With reference toFIG.3, the permanent magnet generator module80includes a housing90, a stator92, a rotor94, and a turbine96mounted to the rotor94along an axis A. The turbine96may be of various configurations to include, for example, gears, screws, etc. The turbine96may be at least partially located in the housing90. The turbine96communicates with the working fluid though the recirculation conduit70that is connected to the permanent magnet generator module80via an inlet100and an outlet102. The recirculation conduit70is in communication with the permanent magnet generator module80via the inlet100and the outlet102. The turbine96is thereby rotated by the working fluid from the recirculation conduit70to power the permanent magnet generator module80. The housing90may also include a cooling path104for the working fluid. The cooling path104circulates the working fluid to facilitate thermal control of the permanent magnet generator module80. Although the different non-limiting embodiments have specific illustrated components, the embodiments are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments. It should be appreciated that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be appreciated that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom. Although particular step sequences are shown, described, and claimed, it should be appreciated that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure. The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be appreciated that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content. | 7,594 |
11859553 | DETAILED DESCRIPTION Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, an illustrative view of an embodiment of a system in accordance with the disclosure is shown inFIG.1and is designated generally by reference character100. Other embodiments and/or aspects of this disclosure are shown inFIGS.2and3. Referring toFIGS.1-3, a fluid injection system100can include a main flow line101configured to pass injectant flow therethrough. The system100can include a primary flow line103connected to the main flow line101and configured to provide a primary portion of the injectant flow from the main flow line101to a primary injector (not shown). The system100can include a primary flow valve105disposed between the primary flow line103and the main flow line101and configured to allow injectant flow to the primary flow line103from the main flow line101in an open primary flow valve state (e.g., as shown inFIGS.1and2), and to prevent injectant flow to the primary flow line103from the main flow line105in a closed primary flow valve state (e.g., as shown inFIG.3). The system100can include a secondary flow line107connected to the main flow line101and configured to provide a secondary portion of the injectant flow from the main flow line101to a secondary injector (not shown). The system100can include a secondary flow valve109disposed between the secondary flow line107and the main flow line101(e.g., on the secondary flow line107) and configured to selectively allow injectant flow to the secondary flow line107from the main flow line101in an open secondary flow valve state (e.g., as shown inFIG.1), and to prevent injectant flow to the secondary flow line107from the main flow line101in a closed secondary flow valve state (e.g., as shown inFIGS.2and3). The system100can include a primary purge branch111configured to be in fluid communication with the primary flow line103in the closed primary flow valve state (e.g., as shown inFIG.3) and to not be in fluid communication with the primary flow line103in the open primary flow valve state (e.g., as shown inFIGS.1and2). The system100can include a secondary purge branch113configured to be in fluid communication with the secondary flow line107in the closed secondary flow valve state (e.g., as shown inFIGS.2and3) and to not be in fluid communication with the secondary flow line107in the open secondary flow valve state (e.g., as shown inFIG.1). The primary purge branch111and the secondary purge branch113can be configured to be in fluid communication with a purge gas line115to receive a purge gas flow from the purge gas line115. In certain embodiments, the primary purge branch111and the secondary purge branch113can form part of the purge gas line115. The purge gas line115can be connected to any suitable purge gas source (e.g., compressor bleed air from a turbomachine). In certain embodiments, e.g., as shown, the first purge branch111and the second purge branch113can be in fluid communication such that there is no valve between the first purge branch111and the second purge branch113. Any other suitable arrangement is contemplated herein. In certain embodiments, the primary flow valve105can be a pressure actuated shuttle valve, e.g., as shown, and can be configured to transition from the closed primary flow valve state (e.g., as shown inFIGS.2and3) to the open primary flow valve state (e.g., as shown inFIG.1) when pressure in the main flow line101exceeds a pressure in the purge gas line115such that the primary flow valve105prevents fluid communication between the primary purge branch111and the primary flow line103when the pressure in the main flow line101exceeds a pressure in the purge gas line115. The primary flow valve105can be connected between the main flow line101and the primary flow line103on a front side105athereof and between the primary purge branch111and the primary flow line103on a back side thereof105b. The primary flow valve105can be configured to block either purge gas from the primary flow line103or injectant from the primary flow line103(e.g., as shown). For example, the primary flow valve105can be configured to block purge gas from the primary flow line103in the open primary flow valve state and to block injectant from the primary flow line103in the closed primary flow valve state. Such an arrangement allows the use of a single valve for primary flow and primary line purging. The secondary flow valve109can be connected between the main flow line101and the secondary flow line107on a first side109athereof and between the secondary purge branch113and the secondary flow line107on a second side thereof109b. The secondary flow valve109can be configured to block either purge gas from the secondary flow line107or injectant from the secondary flow line107(e.g., as shown). For example, the secondary flow valve109can be configured to block purge gas from the secondary flow line107in the open secondary flow valve state and to block injectant from the secondary flow line107in the closed secondary flow valve state. Such an arrangement allows the use of a single valve for secondary flow and secondary line purging. The secondary flow valve109can be a solenoid valve having an energized position and a de-energized position. The energized position can correspond to the open secondary flow valve state and the de-energized position can correspond to the closed secondary flow valve state. The opposite is contemplated herein. The secondary flow valve109can include a pintle type valve, e.g., as shown, or any other suitable type of controllable valve. The system100can include a controller117configured to control the secondary flow valve109to move the secondary flow valve109between the open secondary flow valve state and the closed secondary flow valve state. The controller121can include any suitable hardware module(s) and/or software module(s) to configure to perform and suitable function, e.g., any sequence and/or method disclosed herein. The controller117can be configured to execute a purge sequence from an operational state (e.g., as shown inFIG.1) where injectant flow is flowing through both the primary and secondary flow lines103,107. The purge sequence can include closing the secondary flow valve109to shut off injectant flow to the secondary flow line107from the main flow line while simultaneously causing purge gas flow to purge the secondary flow line107. The purge sequence can include allowing injectant flow in the primary flow line103to reduce in pressure to below the purge gas pressure to cause the primary flow valve105to move to the closed primary flow valve state simultaneously causing purge gas flow to purge the primary flow line103, e.g., after closing the secondary valve109. Any other suitable sequence(s) and/or portion(s) thereof are contemplated herein. In accordance with at least one aspect of this disclosure, a fuel system can include a fluid injection system having a single controllable valve (e.g., secondary valve109) and a single passive valve (e.g., primary valve105) arranged to cause selective and/or sequential purging of a secondary flow line and a primary flow line. The controllable valve and the passive valve can be the only valves in the fluid injection system. The controllable valve can be a solenoid valve. The passive valve can be a pressure actuated shuttle valve. Any other suitable valve types are contemplated herein. In accordance with at least one aspect of this disclosure, a method can include operating a single controllable valve to purge a secondary flow line of a fluid injection system with a purge gas flow, and causing a passive valve to open using a purge gas pressure to cause purging of a primary flow line of the fluid injection system after purging the secondary flow line. Operating the controllable valve can include closing the secondary flow valve to shut off injectant flow to the secondary flow line from the main flow line while simultaneously causing purge gas flow to purge the secondary flow line. Causing a passive valve to open can include allowing injectant flow in the primary flow line to reduce in pressure to below the purge gas pressure to cause the primary flow valve to move to the closed primary flow valve state simultaneously causing purge gas flow to purge the primary flow line. Any other suitable method(s) and/or portion(s) thereof are contemplated herein. Certain embodiments include a combination of a single solenoid and one shuttle valve used to manage fluid and purge air flow. Primary flow can be commanded when a pump is spun up (e.g., either mechanically or electrically), and as the injectant fluid pressure increases above the purge air pressure the passive primary flow valve shuttles to connect the injectant fluid to the primary flow path. One solenoid can be used to switch between injection fluid and purge air on the secondary injection lines and the shuttle valve performs the same function on the primary flow line. Secondary flow can be activated by commanding the solenoid to shuttle the active secondary flow valve into the state that connects the secondary flow path with the injectant fluid. As the operating conditions no longer require secondary injection, the system can command the secondary solenoid to shuttle the valve to connect purge air with the secondary flow path. Purging of the secondary flow line can be user selectable and can be done at any time by, e.g., de-energizing the solenoid. Purge air can then enters the secondary flow path to evacuate any remaining injectant fluid. Once the operating conditions no longer require primary injection, the pump can be commanded off and the fluid pressure begins to decay in the primary flow path. Eventually the fluid pressure will drop to a sufficient level for the purge air pressure to shuttle the passive primary flow valve allowing purge air to flow down the primary flow path. Thus, purging of the primary flow line can be achieved based on system pressures. For example, only once injection fluid pressure has dropped below purge air pressure will the shuttle valve change states allowing purge air to flow down the primary injection line. Certain embodiments can meet engine injection needs and allow purging with only two three-way valves, one passive and one active. Embodiment can provide an ability to have a control system command injectant flow and purge air on/off, while allowing differentiation between primary and secondary purge operation through the use of control laws and passive mechanical valve actuation. Embodiments can reduce the build-up and/or clogging of fluid lines and nozzles, while minimizing the number of solenoids/control valves required to accomplish the task in injection systems for aircraft gas turbines. Embodiments can eliminate the need for a separate solenoids for each fluid in each path (e.g., primary purge air, primary flow, secondary purge air, and secondary flow) which reduces control system complexity (e.g., in control laws, Built-In Test, and reliability). Embodiments can trade four solenoids for a passive valve and one solenoid controlled valve which can reduce recurring costs. As will be appreciated by those skilled in the art, aspects of the present disclosure may be embodied as a system, method or computer program product. Accordingly, aspects of this disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.), or an embodiment combining software and hardware aspects, all possibilities of which can be referred to herein as a “circuit,” “module,” or “system.” A “circuit,” “module,” or “system” can include one or more portions of one or more separate physical hardware and/or software components that can together perform the disclosed function of the “circuit,” “module,” or “system”, or a “circuit,” “module,” or “system” can be a single self-contained unit (e.g., of hardware and/or software). Furthermore, aspects of this disclosure may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon. Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing. Computer program code for carrying out operations for aspects of this disclosure may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). Aspects of the this disclosure may be described above with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of this disclosure. It will be understood that each block of any flowchart illustrations and/or block diagrams, and combinations of blocks in any flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in any flowchart and/or block diagram block or blocks. These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks. The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified herein. Those having ordinary skill in the art understand that any numerical values disclosed herein can be exact values or can be values within a range. Further, any terms of approximation (e.g., “about”, “approximately”, “around”) used in this disclosure can mean the stated value within a range. For example, in certain embodiments, the range can be within (plus or minus) 20%, or within 10%, or within 5%, or within 2%, or within any other suitable percentage or number as appreciated by those having ordinary skill in the art (e.g., for known tolerance limits or error ranges). The articles “a”, “an”, and “the” as used herein and in the appended claims are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article unless the context clearly indicates otherwise. By way of example, “an element” means one element or more than one element. The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and/or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of” or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e., “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” Any suitable combination(s) of any disclosed embodiments and/or any suitable portion(s) thereof are contemplated herein as appreciated by those having ordinary skill in the art in view of this disclosure. The embodiments of the present disclosure, as described above and shown in the drawings, provide for improvement in the art to which they pertain. While the subject disclosure includes reference to certain embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the spirit and scope of the subject disclosure. | 20,291 |
11859554 | DETAILED DESCRIPTION To maintain clarity of this description, some of the same reference numerals have been used in different embodiments to show features that may be common to the different embodiments. FIG.1depicts an exemplary multi-engine aircraft1, which in this case is a helicopter. The aircraft1may however also be a fixed-wing aircraft. The aircraft1includes at least two aircraft engines10(or simply “engines”), labeled inFIG.1as “ENGINE 1” and “ENGINE 2”. In a particular embodiment, these two engines are turboshaft gas turbine engines. However, it is to be understood that one or both of the engines may also and/or alternately be hybrid or other types suitable aircraft engines, and may therefore be at least partially electrically driven. The two engines10may be interconnected by a common gearbox46(seeFIG.2), forming a multi-engine system42as shown inFIG.2and as will be described in further detail below. FIG.2illustrates an exemplary multi-engine system42to be used as a power plant for the aircraft1, which can include but is not limited to a rotorcraft such as the helicopter (H) ofFIG.1. The multi-engine system42may include multiple engines10, and in one embodiment includes two or more engines10A,10B. In the case of a helicopter application, these engines10A,10B may be turboshaft gas turbine engines. They may alternatively be other types of gas turbine engines, or any suitable aircraft engines such as hybrid and/or electrically powered engines. Control of the multi-engine system42is effected by one or more controller(s)29, which may be FADEC(s), electronic engine controller(s) (EEC(s)), or the like, that are programmed to manage, as described herein below, the operation of the engines10A,10B to reduce an overall fuel burn, particularly during sustained cruise operating regimes, wherein the aircraft is operated at a sustained (steady-state) cruising speed and altitude. The cruise operating regime is typically associated with the operation of prior art engines at equivalent part-power, such that each engine contributes approximately equally to the output power of the system42. Other phases of a typical helicopter mission would include transient phases like take-off, climb, stationary flight (hovering), approach and landing. Cruise may occur at higher altitudes and higher speeds, or at lower altitudes and speeds, such as during a search phase of a search-and-rescue mission. When the aircraft conditions, such as cruise speed and altitude, are substantially stable—such as during a cruise flight segment of the aircraft—the engines10A,10B of the system42may be operated asymmetrically, with one engine operated in a high-power “active” mode and the other engine operated in a lower-power “standby” mode. Doing so may provide fuel saving opportunities to the aircraft, however there may be other suitable reasons why the engines are desired to be operated asymmetrically. This operation management may therefore be alternately referred to herein as an “asymmetric mode”, an “asymmetric operating regime” or an “idle cruise regime” (ICR), wherein one of the two engines is operated in a low-power “standby mode” while the other engine is operated in a high-power “active” mode. In such an asymmetric operation, which may be engaged during a cruise phase of flight (continuous, steady-state flight which is typically at a given commanded constant aircraft cruising speed and altitude). This operation management may therefore be referred to as a “asymmetric operation mode”, or an “idle cruise regime” (ICR), wherein one of the two engines is operated in a low-power or “standby mode” (also referred to herein as a “standby operating condition”) while the other engine is operated in a high-power or “active mode”. In the standby mode, an engine provides significantly less propulsive power to the aircraft than does the other engine operating in the higher-power, active mode. In certain embodiments, the engine operating in the standby mode may even provide no or almost no propulsive power to the aircraft. The multi-engine system42may be used in an aircraft, such as but not limited to a helicopter, but also has applications in suitable marine and/or industrial applications or other ground operations. As shown inFIG.2, the multi-engine system42may include a first engine10A and a second engine10B configured to drive a common load44. In the depicted embodiment, the engines10A,10B are turboshaft gas turbine engines. In some embodiments, the common load44may comprise a rotary wing of a rotary-wing aircraft. For example, the common load44may be a main rotor of the helicopter. Depending on the type of the common load44and on the operating speed thereof, turboshaft engines10A,10B may be drivingly coupled to the common load44via a gearbox46, which may be any suitable type, such as a speed-changing (e.g., reducing) type. The gearbox46may have a plurality of transmission shafts48to receive mechanical energy from respective output shafts40A,40B of respective turboshaft engines10A,10B to direct at least some of the combined mechanical energy from the plurality of the turboshaft engines10A,10B to a common output shaft50for driving the common load44at a suitable operating (e.g., rotational) speed. The multi-engine system42may include a transmission52driven by the output shaft40B and driving the rotatable transmission shaft48. The transmission52may be controlled to vary a ratio between the rotational speeds of the respective output shaft40A/40B and transmission shaft48. The multi-engine system42may be configured, for example, to drive accessories of an associated aircraft in addition to the main rotor. The gearbox46may be configured to permit the common load44to be driven by either the first turboshaft engine10A or the second turboshaft engine10B, or, by a combination of both the first turboshaft engine10A and the second turboshaft engine together10B. A clutch53may be provided to permit each engine10A,10B to be engaged and disengaged with the transmission X, as desired. For example, an engine10A,10B running at low- or no-power conditions may be declutched from the transmission if desired. In some embodiments, a conventional clutch may be used. Referring still toFIG.2, according to the present description the multi-engine system42driving a helicopter (H) or other aircraft1may be operated in such an asymmetric manner, in which a first one of the engines (say,10A) is operated at high power in an active mode and the second one of the engines, for instance the engine10B in this example, is capable of being operated in a low-power standby mode. In one example, the first engine10A may be controlled by the controller(s)29to run at full (or near-full) power conditions in the active mode, to supply substantially all or all of a required power and/or speed demand of the common load44and thus the aircraft. The second engine10B may be controlled by the controller(s)29to operate at low-power or no-output-power conditions to supply one of substantially little, substantially none or none of a required power and/or speed demand of the common load44. Optionally, a clutch may be provided to declutch the low-power engine. Controller(s)29may control the engine's governing on power according to an appropriate schedule or control regime. The controller(s)29may comprise a first controller for controlling the first engine10A and a second controller for controlling the second engine10B. The first controller and the second controller may be in communication with each other in order to implement the operations described herein. In some embodiments, a single controller29may be used for controlling the first engine10A and the second engine10B. The term controller as used herein includes any one of: a single controller controlling the engines, and any suitable combination of multiple controllers controlling the engines, including one or more controllers for each engine, so long as the functionality described in this document is provided. In another example, an asymmetric operating regime of the engines may be achieved through the one or more controller's29differential control of fuel flow to the engines, as described in pending application Ser. No. 16/535,256 filed Aug. 8, 2019, the entire contents of which are incorporated herein by reference. Low fuel flow may also include zero fuel flow in some examples. Although various differential control between the engines of the engine system42are possible, in one particular embodiment the controller(s)29may correspondingly control fuel flow rate to each engine10A,10B accordingly. In the case of the standby engine, a fuel flow (and/or a fuel flow rate) provided to the standby engine may in certain embodiments be controlled to be between 70% and 99.5% less than the fuel flow (and/or the fuel flow rate) provided to the active engine. In the asymmetric mode, the standby engine may be maintained between 70% and 99.5% less than the fuel flow to the active engine. In some embodiments, the fuel flow rate difference between the active and standby engines may be controlled to be in a range of 70% and 90% of each other, with fuel flow to the standby engine being 70% to 90% less than the active engine. In some embodiments, the fuel flow rate difference may be controlled to be in a range of 80% and 90%, with fuel flow to the standby engine being 80% to 90% less than the active engine. In other possible embodiments, the standby engine may be completely shut down, such that no fuel flow is used by this engine when it is operating in the standby mode. In such a case, therefore, the fuel flow (which is zero) to the standby engine is thus 100% less than the fuel flow to the active engine. It is therefore to be understood that the term “standby” mode as used herein is intended to include, in certain embodiments, a complete shut-down state of the standby engine, whereby only one of the two engines (i.e. the active engine) is in operation. A complete shut down of the second engine placed into the standby mode may be particularly interesting given that it completely eliminates fuel consumption by that engine, thereby reducing fuel consumption and thus fuel costs, while also reducing the total flight hours of the engine, thereby reducing related maintenance and operating costs. In another embodiment, the controller29may operate one engine of the multiengine system42, for instance the engine10B, in a standby mode at a power substantially lower than a rated cruise power level of the engine, and in some embodiments at zero output power and in other embodiments less than 10% output power relative to a reference power (provided at a reference fuel flow). Alternately still, in some embodiments, the controller(s)29may control the standby engine to operate at a power in a range of 0% to 1% of a rated full-power of the standby engine (i.e. the power output of the second engine to the common gearbox remains between 0% to 1% of a rated full-power of the second engine when the second engine is operating in the standby mode). In another example, the multi-engine system42ofFIG.2may be operated in an asymmetric operating regime by control of the relative speed of the engines using controller(s)29, that is, the standby engine is controlled to a target low speed and the active engine is controlled to a target high speed. Such a low speed operation of the standby engine may include, for example, a rotational speed that is less than a typical ground idle speed of the engine (i.e. a “sub-idle” engine speed). Still other control regimes may be available for operating the engines in the asymmetric operating regime, such as control based on a target pressure ratio, or other suitable control parameters. In use, the first turboshaft engine (say10A) may operate in the active mode while the second turboshaft engine, such as the engine10B, may operate in the standby mode, as described above. Although the examples described herein illustrate two engines, asymmetric mode is applicable to more than two engines, whereby at least one of the multiple engines is operated in a low-power standby mode while the remaining engines are operated in the active mode to supply all or substantially all of a required power and/or speed demand of a common load. During such asymmetric operation, if the helicopter (H) needs a power increase (expected or otherwise), the second turboshaft engine10B may be required to provide more power relative to the low power conditions of the standby mode, and possibly rapidly to a high-power or full-power condition. In such situations, the engine10B operating previously in a low power condition must be able to quickly accelerate back up to cruise or full power output levels. This may be required, for example, in the event of an emergency or an urgent need for increased power (e.g. if the pilot requires additional power in order to perform a desired manoeuver). In certain conditions/applications, it may also be possible to completely shut down the second engine10B engine. However, to do so would require the ability to rapidly re-start the second engine in the event of an emergency or sudden need for more power. Even absent an emergency, it will be desirable to repower the standby engine to exit the asymmetric mode, such that the two engines operate in a normal cruise operating regime whereby both engines operate at similar power output levels (e.g. each engine provides about 50% of the total power output provided to the aircraft). As will be described in further detail below with reference toFIGS.4and5, the multi-engine system42of the present disclosure includes an air accumulation system70which is operable to assist an engine operating in a low power condition to quickly accelerate back up to cruise or full power output levels. As will be seen, this is accomplished by introducing external compressed air from outside the engines10A,10B into the engine to be accelerated, in order to assist its rapid acceleration back up to cruise or full power. More particularly, compressed air is extracted (e.g. bled off) form one or both engines10A,10B of the multi-engine system42and accumulated in a tank or pressure vessel80that is external to both engines10A,10B. When rapid re-acceleration of an engine operating in a stand-by mode becomes required, for example in response to a power demand, then the compressed air that has been accumulated in the external pressure vessel80is introduced (or re-introduced, as the case may be) into the cold section of the engine in order to permit it to more rapidly accelerate to a higher power output. The cold section of the engine is understood to be located upstream of a combustor16of the engine, and more particularly is defined as extending from an air inlet of the engine22to, but not including, a combustion zone located within the combustion chamber liner of the combustor16. Before additional details of the air accumulation system70and its method of operation are described, each of the engines10,10A,10B of the multi-engine system42will first be described in further detail, with reference toFIGS.2and3. As shown inFIGS.2and3, each aircraft engine10A,10B (identified simply as engine10inFIG.3) of the multi-engine system42may, as in the depicted embodiment, be a turboshaft gas turbine engine generally comprising in serial flow communication a low pressure (LP) compressor section, which will be referred to herein as the LP compressor12and a high pressure (HP) compressor section, which will be referred below as the HP compressor14for pressurizing air received via an air inlet22. The air compressed by the LP compressor12and by the HP compressor14is fed to a combustor16in which the compressed air is mixed with a fuel flow, delivered to the combustor16via fuel nozzles17from a suitable fuel system, and ignited for generating a stream of hot combustion gases. A high pressure turbine section, which will referred to herein as the HP turbine18, extracts energy from the combustion gases. A low pressure turbine section, which will be referred to herein as the LP turbine20is located downstream of the HP turbine18for further extracting energy from the combustion gases and driving the LP compressor12. The combustion gases are then exhausted by an exhaust outlet24. The LP compressor12may include one or more compression stages, and the HP compressor14may include one or more compression stages. In the embodiment shown, the turboshaft engine10includes a low-pressure spool, referred to below as LP spool26, and a high-pressure spool, referred to below as a HP spool28. The LP spool26includes a low-pressure shaft, referred to below as LP shaft32. The HP spool28includes a high-pressure shaft, referred to below as HP shaft34. The HP turbine18is drivingly engaged to the HP compressor14via the HP shaft34. The LP turbine20is drivingly engaged to the LP compressor12via the LP shaft32. The HP spool28, and the components mounted thereon, are configured to rotate independently from the LP spool26and from the components mounted thereon. These two spools may thus rotate at different speeds about an engine central axis30. The HP shaft34and the LP shaft32may be concentric. In the embodiment shown, the HP shaft34extends around the LP shaft32. The term “spool” is herein intended to broadly refer to drivingly connected turbine and compressor rotors, and need not mean the simple shaft arrangements depicted. Although the gas turbine engine10as shown inFIG.3is a multi-spool engine, having separate LP spool26and HP spool28, it is to be understood that in an alternate embodiment, one or more of the engines10A,10B of the multi-engine system42may have a single spool architecture, which is often the case for auxiliary power unit (APU) engines used in aircraft. In the embodiment shown, the HP compressor14rotates at the same speed as the HP turbine18. And, the LP compressor12rotates at the same speed as the LP turbine20. However, this may not be the case if transmission(s) are provided on the LP spool26and HP spool28to create speed ratios between the interconnected compressors and turbines. This may increase or decrease rotational speeds of the compressors relative to that of the turbines. Any suitable transmissions may be used for this purpose. The turboshaft engine10may include a transmission38driven by the low pressure shaft32and driving a rotatable output shaft40. The transmission38may be provided to vary a ratio between rotational speeds of the low pressure shaft32and the output shaft40. The LP compressor12and the HP compressor14are configured to deliver desired respective pressure ratios in use, as will be described further below. The LP compressor12of the engine10(and therefore of each of the engines10A,10B ofFIGS.2and4) may have a bleed valve13(shown schematically) configured to selectively bleed air from the LP compressor12, via an associated bleed port, according to a desired control regime of the engine10, for example to assist in control of compressor stability. As mentioned, the HP compressor14is configured to independently rotate from the LP compressor12by virtue of their mounting on different engine spools. The HP compressor14may include one or more compression stages, such as a single stage, or two or more stages as shown in more detail inFIG.2. It is contemplated that the HP compressor14may include any suitable type and/or configuration of stages. The HP compressor14is configured to deliver a desired pressure ratio in use, as will be described further below. The HP compressor14may have a bleed valve15(shown schematically) which may be configured to selectively bleed air from the HP compressor14, via an associated bleed port, according to a desired control regime of the engine10, for example to assist in control of compressor stability. One or both of the bleed valve13located within the LP compressor12and the HP compressor14may also serve as accumulator injection/bleed ports86A,86B, as shown inFIG.4and described further below as part of the air accumulation system70. Alternately, the engine10(and thus the two engines10A,10B) may each include regular bleed valve13and/or15, in addition to at least one accumulator injection/bleed ports86A,86B as described below. In one particular embodiment, the accumulator injection/bleed ports86A,86B may be located within the HP compressor14, for example just upstream of the combustor (at an engine station often referred to as “P3”, where the static pressure of the compressed air produced by the compressor(s) of the engine is the highest). Regardless of the chosen configuration, both the standard compressor bleed valves13,15and the accumulator injection/bleed ports86A,86B are located within the “cold section” of the engine, that is upstream of the combustor16within the engine. Further details of the accumulator injection/bleed ports86A,86B will be provided below. The expression “upstream of the combustor” as used herein, particularly with reference to the location at which compressed air from the pressure vessel80is introduced into the second engine, is therefore understood to mean anywhere within the cold section of the engine, between the air inlet22and the combustor16(and more precisely the combustion zone contained within the combustion chamber liner(s) of the combustor). This includes the air plenums, cavities or passages which may surround the combustor16, even if some or all of such plenums, cavities or passages are axially located at or forward of the combustion chamber liner itself), at which location(s) the pressure of the compressed air (e.g. P3 air) is the highest. In use, suitable one or more controllers29, such as one or more full authority digital controllers (FADEC) providing full authority digital control of the various relevant parts of the engine10, controls operation of the engine10. The FADEC(s) may be provided as for example conventional software and/or hardware, so long as the FADEC(s) is/are configured to perform the various control methods and sequences as described in this document. Each controller29may be used to control one or more engines10of an aircraft (H). Additionally, in some embodiments the controller(s)29may be configured for controlling operation of other elements of the aircraft (H), for instance the main rotor44. Referring still toFIGS.2and3, the turboshaft engine10may also include variable guide vanes (VGVs)36,36A,36B. As seen inFIG.2, a first set of VGVs36A is located upstream of the LP compressor12, and a second set of VGVs36B is located upstream of the HP compressor14. The VGVs36may be independently controlled by suitable one or more controllers29, as described above. The VGVs36may direct inlet air to the corresponding stage of the LP compressor12and of the HP compressor14. The VGVs36may be operated to modulate the inlet air flow to the compressors in a manner which may allow for improved control of the output power of the turboshaft engine10, as described in more detail below. The VGVs36may be provided with any suitable operating range. In some embodiments, VGVs36may be configured to be positioned and/or modulated between about +80 degrees and about −25 degrees, with 0 degrees being defined as aligned with the inlet air flow. In a more specific embodiment, the VGVs36may rotate in a range from +78.5 degrees to −25 degrees, or from +75 degrees to −20 degrees, and more particularly still from 70 degrees to −20 degrees. The two set of VGVs36may be configured for a similar range of positions, or other suitable position range. In some embodiments, the first set of VGVs36A upstream of the LP compressor12may be mechanically decoupled from the second set of VGVs36B upstream of the HP compressor14and downstream of the LP compressor12, having no mechanical link between the two sets of VGVs to permit independent operation of the respective stages. The VGVs36may be operatively controlled by the controller(s)29described above, to be operated independently of each other. Indeed, the turboshaft engine10is also controlled using controller(s)29described above, to carry out the methods described in this document. For the purposes of this document, the term “independently” in respects of the VGVs36means that the position of one set of the VGV vanes (e.g.36A) may be set without effecting any change to a position of the other set of the VGV vanes (e.g.36B), and vice versa. Independent control of the VGVs36may allow the spools26,28to be operated to reduce or eliminate or reduce aerodynamic coupling between the spools26,28. This may permit the spools26,28to be operated at a wider range of speeds than may otherwise be possible. The independent control of the VGVs36may allow the spools26,28to be operated at constant speed over a wider operating range, such as from a “standby” speed to a “cruise” power speed, or a higher speed. In some embodiments, independent control of the VGVs36may allow the spools26,28to run at speeds close to maximum power. In some embodiments, independent control of the VGVs36may also allow one of the spools26,28to run at high speed while the other one run at low speed. In use, the turboshaft engine10is operated by the controller(s)29described above to introduce a fuel flow via the nozzles17to the combustor16. Combustion gases turn the HP turbine18and the LP turbine20which in turn drive the HP compressor14and the LP compressor12. The controller(s)29control(s) the angular position of VGVs36in accordance with a desired control regime, as will be described further below. The speed of the engine10is controlled, at least in part, by the delivery of a desired fuel flow rate to the engine, with a lower fuel flow rate causing the turboshaft engine10to operate at a lower output speed than a higher fuel flow rate. Referring now toFIG.4, the multi-engine system42also includes an air accumulation system70which includes an air tank or pressure vessel80, which is external to both the first and second engines10A,10B, an serves to receive and retain therein compressed air that is bled off from one or both of the engines10A,10B. As will be described in further detail, once the pressure vessel80is filled, either partially or fully, with compressed air, it is stored therein until such as time as it is needed for injection, or re-injection, into one of the two engines10A,10B that is operating in a standby mode as described above. Accordingly, in certain embodiments the standby engine can be completely shut down, once there is sufficient air pressure in the pressure vessel80. The external pressure vessel80will have an internal volume that is sufficient to guarantee engine start when the compressed air stored in the pressure vessel is injected back into the standby engine when required for an emergency re-start and/or rapid acceleration. The pressure vessel80is external to both engines10A,10B, and may be physically located either within the overall multi-engine system package or may alternately be located elsewhere within the aircraft. While it will be appreciated that the pressure vessel80must be suitable to hold compressed air having a pressure corresponding to the air pressures generated by the engines, the exact construction of the pressure vessel80may be selected to be suitable for the purposes described herein. In certain embodiments, the pressure vessel80may be inflatable, such that it remains lightweight and when it is empty (and thus is deflated) it will take up relatively little space within the aircraft. Additionally, in certain embodiments, the external pressure vessel80may also be thermally insulated, so as to help to retain the heat in the extracted air that was generated when it was compressed. Alternately still, the pressure vessel80may also be cooled, either passively or actively using a suitable heat-exchanger for example. This may be useful so as to increase the storage capacity, in terms of total mass of the compressed air accumulated therein at a given pressure, thereby allowing—when the accumulated air is injected back into the re-acerbating engine—more fuel flow into the combustion chamber before reaching the hot section temperature limit. Thus, the pressure vessel80is fluidly connected to each of the first engine10A and the second engine10B by one or more air conduits82A,82B which define each one or more airflow paths between an internal cavity of the pressure vessel80and the cold section of a respective one of the engines10A,10B. More particularly, each of the air conduits82A,82B may provide a first, accumulation, flow path used to transport compressed air from the cold section of the respective engines10A,10B (i.e. from the compressor(s), upstream of the combustors) to the pressure vessel80, and a second, injection, flow path used to transport compressed air from the pressure vessel80to the cold section of the respective engines10A,10B. It is to be understood, however, that a single conduit82A,82B can be used to direct air to and from each respective engine10A,10B, such that air flows out of the engines and into the engines through the same passage, line or conduit. Although the depicted embodiment shows only a single pressure vessel80, it is to be understood that two or more pressure vessels may also be used. For example, each engine10A,10B may have its own dedicated pressure vessel80, within which air is accumulated and stored for sub-sequent delivery to is respective engine. Each of the first and second engines10A,10B includes a respective accumulator injection/bleed port86A,86B located within the cold section of the engine. These ports86A,86B may also be simply referred to herein as “bleed ports” even if they may also serve to inject compressed air flow into the engine in addition to or in stead of being used to bleed compressed air off from the engine for filling the pressure vessel80. In the depicted embodiment, the accumulator bleed ports86A,86B are located within the HP compressor14A,14B, just upstream of their respective combustors16A,16B. Thus, the air bled off via the accumulator bleed ports86A,86B, when one or more associated control valves84A,84B are opened, and subsequently stored in the pressure vessel80, will have a high pressure. These control valves84A,84B may also be, or include, one-way valves such as to prevent flow of the compressed air in an unwanted direction. The control valves84A,84B are thus operable to control the flow of air to and from the pressure vessel80, and thus to control the injection of the pressurized air contained within the pressure vessel80into one of the engines, when it becomes desirable to do so in the manner described herein. In the depicted embodiment, a first control valve84A is disposed in flow communication with the first air conduit82A and a second control valve84B is disposed in flow communication with the second air conduit82B, wherein the first and second control valves84A,84B can be used to either allow or prevent flow between the cold sections of the engines10A,10B and the pressure vessel80. In an alternate embodiment, a single, multi-port, valve may be able to be used in place of the two separate control valves84A,84B, provided that independent flow within each of the first and second air conduits82A,82B can be separately controlled. As such, compressed air can be drawn or bled off from only one or both of the engines10A,10B via one or both of the accumulator bleed ports86A,86B located within the cold section of the engines, as controlled by the one or both control valves84A,84B prior to the shut-down (or reduction of power output) of one of the two engines into a low-power standby mode. The air extracted in this manner is accordingly directed through the respective one(s) of the first and second air conduits82A,82B (depending of course on which port is opened to allow bleed flow therethrough) to the pressure vessel80, where the compressed air is accumulated, and retained future use. This accumulated of the compressed air within the pressure vessel80may, in one particular embodiment, be done gradually, while the engine from which the air is extracted is operating at standard cruise or high power (e.g. a high pressure ratios). For example, in one operation scenario, high pressure air is drawn off from the HP compressor14B of the second engine10B, via its accumulator bleed port86B, right from the beginning of a normal flight mission, as the engine10B starts, then idles, then gets to take-off power. Because the pressure at this location of the engine will increase over a sufficiently long time interval, and the volume of compressed air extracted via accumulator bleed port86B and fed to the pressure vessel80remains relative small (i.e. relative to the total volume of air flowing through the HP compressor14B) throughout, this small extraction of flow from the HP compressor14B will not be “perceptible” to the overall engine operability—in other words, this relatively small amount of compressed air that is extracted for feeding to the pressure vessel80will have little to no impact on the overall performance and operability of the engine. However, if the compressed air used to fill the pressure vessel80is extracted from either engine while the engine or engines are already operating in a high power regime (e.g. following an emergency re-start or acceleration for instance), then it may be desirable to bleed this air off slowly, again via the accumulator bleed ports86A,86B, such as to prevent compressor surge and limit performance penalties. For that purpose, a servo valve (controlled via the FADEC for instance) could be used. Such a servo valve may form part of the control valve or valves84A,84B, or may be an additional servo valve(s) in other instances. Further, when the external pressure vessel80has been “charged” (i.e. filled, either partially or fully, with the accumulated compressed air), and the second engine10B has been shut down or placed into a low power operating condition, it is also possible to use the first engine10A (e.g. the active engine operating a regular cruise or full power) to add small amounts of additional compressed air into the external pressure vessel80—e.g. either periodically or using a small but continuous trickle flow. In this manner, the compressed air within the pressure vessel80can be “topped up” using air extracted from the active engine. This may help to keep the pressure within the external pressure vessel80at a desired level and/or may be used to replenish any lost or used accumulated compressed air, which may be particularly useful if there is a cooling mechanism in place that could cause the pressure within the pressure vessel80to drop. In this manner, both the volume and pressure of the accumulated compressed air within the external pressure vessel can be maintained at desired levels, so as to ensure that if/when this accumulated air is needed it will be sufficient for injection into the standby engine for emergency start-up and/or rapid acceleration of the standby or shut-down engine. In one possible scenario, at the end of aircraft take-off, compressed air from one engine (e.g. second engine10B) may have been slowly bled off and fed to the external pressure vessel80such that this external pressure vessel80is fully “charged” with compressed air. The second engine10B can then be shut down or placed in very low power standby mode, as described above, once the aircraft has reached its flight cruise phase, with the accumulated compressed air stored in the external pressure vessel80. When/if needed for an emergency re-start or power recovery of the second engine10B, the accumulated compressed air retained in the pressure vessel80is then fed back into the compressor of the shut-down engine10B to enable a rapid re-start thereof. With specific respect to the introduction of the compressed air from the pressure vessel80into the cold section of the engine operating in a standby mode, when required for the purposes of executing an emergency re-start and/or a rapid acceleration of the low power standby engine, this injection of the accumulated compressed air is optimally done somewhere between the inlet22A,22B of the engine in question and the combustor16A,16B thereof (i.e. somewhere within the cold section of the engine. The precise location that this accumulated compressed air is injected into the cold section may vary, and is selected depending on the particular engine architecture (e.g. number of compressor stages, compressor inertia, etc.) and the available compressed air (volume, pressure) as well as the desirable engine power recovery time. However, in one particular embodiment, the injection of the compressed air from the pressure vessel80into the standby engine, when it needs to be rapidly re-accelerated and/or started, may be done at or just upstream of the HP compressor14A,14B of the engine so as to rapidly spin-up the HP spool28(seeFIGS.2and3). In such an embodiment, therefore, the injection of the accumulated compressed air stored in the external pressure vessel80may be done at a point upstream of the HP compressor14,14A,14B (e.g. impeller), which will cause the HP impeller14,14A,14B to rotate as the accumulated compressed air flows therethrough. This may help to facilitate the re-start. In an alternate embodiment, however, the accumulated compressed air from the pressure vessel80can be injected into the standby engine at a location that is just downstream end of the HP compressor14,14A,14B and immediately upstream of the combustor16,16A,16B. Additionally, in one particular embodiment, the air accumulated in the pressure vessel80can also be injected or re-injected back into the standby engine via the same accumulator bleed ports86A,86B described above, which may have been used to extract the compressed air in the first place. Regardless of the specific location at which the accumulated compressed air from the pressure vessel80is injected into the engine that needs to be rapidly re-started or accelerated to full power, an active control system90may be provided to control this re-injection of the external compressed air from the pressure vessel80. The actively controlled reinjection system90, which is in communication with the engine controller29(also referred to herein simply as FADEC29) (seeFIGS.2-3) and is controlled thereby, may for example include at least one active valve (which may be, for example, one for each engine) and/or a pressure regulating valve which are collectively operable to control the injection of the compressed air. For example, the actively controlled reinjection system90may be configured to permit a more constant flow of the compressed air being injected back into the standby engine, and thus may avoid having too much compressed air injected back into the engine too early, thus avoiding all of the accumulated compressed air being used up and consequently ensuring that there is sufficient compressed air for use in a later phase of the start and re-acceleration sequence of the engine as it starts back up. The actively controlled reinjection system90may also include, or alternately form part of, the control valve or valves84A,84B and/or servo valves, all controlled via the FADEC, used for the extraction of the accumulated compressed air in the first place. Thus, in certain embodiments, a single flow control system (e.g. the system90) that is itself controlled by the FADEC, may be used to control both compressed air extraction from one or both engines, and the injection of the accumulated compressed from the external pressure vessel80into the standby engine when required for a rapid re-acceleration thereof. When the accumulated compressed air is introduced back into the shut-down engine for the purposes of emergency restart or acceleration, the regular starter of the engine in question may still be used to re-start the engine. However, in certain situations, the flight conditions (e.g. altitude, temperature, Mach number, etc. and the operating status of each of the engines (e.g. out of usage, shut-down, sub-idle, idle, low or high power) may permit the engine to be re-started without requiring the use of the regular starter. Additionally, a suitable flow blocking system88A,88B may also be provided within each engine10A,10B to prevent the accumulated high pressure compressed air within the pressure vessel80, when re-injected back into the shut-down engine, from flowing backwards through the engine (e.g. from the re-injection point within the cold section of the engine upstream through the main gas path of the engine core towards the air inlet of the engine, rather than downstream to the combustor). This may be achieved, for example, using one or more one-way valves or another backflow prevention system—e.g. valves or other devices to block the exits of HP compressor diffuser pipes, for example when the injection point is done past that component. Additionally, other engine components, such as variable guides vanes for instance, could also be used to block the compressor gas path when the compressor air is injected downstream that component and upstream to one or more compressor stage. Solutions for improving operating fuel efficiencies of multi-engine systems, such as the present multi-engine system42as described herein, have been proposed in other disclosures. One such example is described in U.S. patent application Ser. No. 16/560,365 filed Sep. 4, 2019, the entire contents of which are incorporated herein, which describes a specific control logic for achieve fuel economy of a multi-engine system. In this document, a “breathing cycle” of an engine is described, wherein rotor inertia is used for energy accumulation and then re-used during a suitable point in the breathing cycle. It is of note that the compressed air accumulated in the external pressure vessel80of the present disclosure may be used in a similar manner, namely in order to extend the time of the “breathing phase” when fuel flow is low. Referring now toFIG.5, a method of operating the multi-engine system42of an aircraft is shown at500. In accordance with the present description, there is therefore provided a method500of operating a multi-engine system42of an aircraft1, such as helicopter H, having a first engine10A and a second engine10B. The method500includes: accumulating compressed air in a pressure vessel80that is external to the first and second engines10A,10B, at step502; operating the first and second engines asymmetrically, by controlling the first engine10A to operate in an active, or high power, operating condition wherein it provides sufficient power and/or rotor speed to meet the demands of the aircraft, and controlling the second engine10B to operate in a standby operating condition wherein the second engine10B produces less power output than the first engine10A, at504; and, in response to a power demand request, accelerating the second engine10B by introducing the compressed air from the pressure vessel80into the second engine10B at a location therein upstream of a combustor16B of the second engine10B, at506. Because this location at which the compressed air is introduces is within the cold section of the engine, it is necessarily downstream of an air inlet22B of the second engine. Step502of the method500may include extracting bleed air from one or more of the first engine10A and the second engine10B, and feeding the bleed air into the pressure vessel80. Additionally, extracting the bleed air may include extracting the bleed air from one or more of a high pressure compressor14A of the first engine10A and a high pressure compressor14B of the second engine10B. Extracting the bleed air may also include extracting the bleed air from the second engine10B prior to the second engine being controlled to produce less power output than the first engine10A. Step502may also include gradually extracting the bleed air from both the one or more of the first and second engines from a beginning of a flight mission, after the one or more of first and second engines is started or after the aircraft has taken-off. Additionally, accumulating the compressed air may include using one or more valves, such as servo control valves operated by the engine controller or FADEC29, to control the extracting of the bleed air. Accumulating the compressed air may also include extracting additional bleed air from the first engine10A, after the second engine10B has been controlled to produce less power output than the first engine. At step506of the method500, introducing the compressed air from the pressure vessel80may include injecting the compressed air into the second engine10B upstream of the high pressure compressor14B of the second engine10B, such as to rapidly spin (e.g. to “spin-up”) a high pressure spool28of the second engine10B (the high pressure spool28including the high pressure compressor14B mounted thereon). At step502, both extracting the bleed air to accumulate the compressed air in the pressure vessel and introducing the compressed air into the second engine may be carried out via one or more common ports in the second engine10B, such as the port86B for example. Step504may include operating the second engine10B to provide minimal or no propulsive power to the aircraft. Step506may include accelerating the second engine10B from the standby operating condition to an active operating condition corresponding to that of the first engine. Operating the first and second engines10A,10B asymmetrically, as in step504, may be performed during a cruise flight segment of the aircraft. At step506, prior to the introducing of the compressed air from the pressure vessel80into the second engine10B at said location upstream of the combustor16B, there may also include blocking a main gas path of the second engine10B upstream of said location to prevent back-flow of the compressed air through the main gas path of the second engine. The method500may be used for example to operate the multi-engine engine system42during, in one example, a cruise flight segment which may be described as a continuous, steady-state flight segment which is typically at a relatively constant cruising speed and altitude. In a typical cruise mode for twin-engine helicopters, both engines provide ˜50% of the cruise power demand of the helicopter. This power level of each engine (˜50% of total power required by the helicopter) may be referred to herein as a “cruise power level”. Step504of the method500can include using the engine controller29, such as a full authority digital control (FADEC)29to control the engines10A,10B to operate asymmetrically. The FADEC29may thus determine that the aircraft is in a suitable condition for entering asymmetric mode, for example during a cruise flight segment. The FADEC29may accelerate one engine (say10A) of the multiengine system42from a cruise power level into an active engine mode, in which the first engine may provide a higher cruise power level and sufficient power to satisfy substantially all or all (e.g. 90% or higher) of a helicopter power or rotor speed demand. The FADEC29may then decelerate another engine (say10B) of the multi-engine system42to operate in a standby mode (as described herein) at a power substantially lower than cruise power level, and in some embodiments at zero output power (i.e. the standby engine is completely shut down) and in other embodiments less than 10% output power relative to a reference power (provided at a reference fuel flow). With reference toFIG.6, an example of a computing device600is illustrated. For simplicity only one computing device600is shown but the system may include more computing devices600operable to exchange data. The computing devices600may be the same or different types of devices. The controller29may be implemented with one or more computing devices600. Note that the controller29can be implemented as part of a full-authority digital engine controls (FADEC) or other similar device, including electronic engine control (EEC), engine control unit (ECU), electronic propeller control, propeller control unit, and the like. In some embodiments, the controller29is implemented as a Flight Data Acquisition Storage and Transmission system, such as a FAST™ system. The controller29may be implemented in part in the FAST™ system and in part in the EEC. Other embodiments may also apply. The computing device600comprises a processing unit602and a memory604which has stored therein computer-executable instructions606, which serve to control the engine system in the manner described herein. More particularly, the processing unit602may comprise any suitable devices configured to implement the method500such that instructions606, when executed by the computing device600or other programmable apparatus, may cause the functions/acts/steps performed as part of the method500as described herein to be executed. The processing unit602may comprise, for example, any type of general-purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, a central processing unit (CPU), an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, other suitably programmed or programmable logic circuits, or any combination thereof. The memory604may comprise any suitable known or other machine-readable storage medium. The memory604may comprise non-transitory computer readable storage medium, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. The memory604may include a suitable combination of any type of computer memory that is located either internally or externally to device, for example random-access memory (RAM), read-only memory (ROM), compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or the like. Memory604may comprise any storage means (e.g., devices) suitable for retrievably storing machine-readable instructions606executable by processing unit602. The methods and systems for operating the multi-engine system described herein may be implemented in a high level procedural or object oriented programming or scripting language, or a combination thereof, to communicate with or assist in the operation of a computer system, for example the computing device600. Alternatively, the methods and systems for operating the multi-engine system may be implemented in assembly or machine language. The language may be a compiled or interpreted language. Program code for implementing the methods and systems for operating the multi-engine system may be stored on a storage media or a device, for example a ROM, a magnetic disk, an optical disc, a flash drive, or any other suitable storage media or device. The program code may be readable by a general or special-purpose programmable computer for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein. Embodiments of the methods and systems for operating the multi-engine system may also be considered to be implemented by way of a non-transitory computer-readable storage medium having a computer program stored thereon. The computer program may comprise computer-readable instructions which cause a computer, or more specifically the processing unit602of the computing device600, to operate in a specific and predefined manner to perform the functions described herein, for example those described in the method500. Computer-executable instructions may be in many forms, including program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types. Typically the functionality of the program modules may be combined or distributed as desired in various embodiments. The embodiments described herein are implemented by physical computer hardware, including computing devices, servers, receivers, transmitters, processors, memory, displays, and networks. The embodiments described herein provide useful physical machines and particularly configured computer hardware arrangements. The embodiments described herein are directed to electronic machines and methods implemented by electronic machines adapted for processing and transforming electromagnetic signals which represent various types of information. The embodiments described herein pervasively and integrally relate to machines, and their uses; and the embodiments described herein have no meaning or practical applicability outside their use with computer hardware, machines, and various hardware components. Substituting the physical hardware particularly configured to implement various acts for non-physical hardware, using mental steps for example, may substantially affect the way the embodiments work. Such computer hardware limitations are clearly essential elements of the embodiments described herein, and they cannot be omitted or substituted for mental means without having a material effect on the operation and structure of the embodiments described herein. The computer hardware is essential to implement the various embodiments described herein and is not merely used to perform steps expeditiously and in an efficient manner. The term “connected” or “coupled to” may include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). The technical solution of embodiments may be in the form of a software product. The software product may be stored in a non-volatile or non-transitory storage medium, which can be a compact disk read-only memory (CD-ROM), a USB flash disk, or a removable hard disk. The software product includes a number of instructions that enable a computer device (personal computer, server, or network device) to execute the methods provided by the embodiments. The embodiments described in this document provide non-limiting examples of possible implementations of the present technology. Upon review of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made to the embodiments described herein without departing from the scope of the present technology. Yet further modifications could be implemented by a person of ordinary skill in the art in view of the present disclosure, which modifications would be within the scope of the present technology. Thus, the above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. For example, the multi-engine system may have more than two engines, in which case any suitable number of the engines may operate in the active and standby modes, respectively. Additionally, although turboshaft engines have been generally described, the engines of the multi-engine system can alternately be other types of gas turbine engines, and they can also be other types of suitable aircraft engines, including for example engines which include electrical components for motive power—provided of course that these engines can benefit from compressed air injection therein for the purposes of accelerating a standby engine back up to a motive power, in the manner described hereinabove. Further still, the engines of the multi-engine system need not all be of the same type, wherein for example one or more of the engines is a gas turbine engine and the other is a fully electric or hybrid engine, for example. It also to be understood that a single engine system, such as shown inFIG.3, may also be operated in a low power regime, without the context of a multi-engine system, and thus the systems and methods described herein may also be used in the context of a single engine. For example, a very low speed “sub-idle” or “standby” operation of a single-engine system may also be desirable in some circumstances, such as on the ground. While the present specification describes the multi-engine system used in a rotorcraft, such as helicopter H, it can applied to other types of multi-engine aircraft or power systems, such as marine and industrial power systems. The engine controller may be any suitable, and the methods of effecting engine control also do not form any part of this description other than as expressly provided. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure. | 57,016 |
11859555 | It will be noted that throughout the appended drawings, like features are identified by like reference numerals. DETAILED DESCRIPTION FIG.1illustrates a gas turbine engine10of a type provided for use in subsonic flight, generally comprising in serial flow communication, a fan12through which ambient air is propelled, a compressor section14for pressurizing the air, a combustor16in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section18for extracting energy from the combustion gases. High pressure rotor(s)20of the turbine section18are drivingly engaged to high pressure rotor(s)22of the compressor section14through a high pressure shaft24. Low pressure rotor(s)26of the turbine section18are drivingly engaged to the fan rotor12and to low pressure rotor(s)30of the compressor section14through a low pressure shaft28extending within the high pressure shaft24and rotating independently therefrom. Although illustrated as a turbofan engine, the gas turbine engine10may alternatively be another type of engine, for example a turboshaft engine, also generally comprising in serial flow communication a compressor section, a combustor, and a turbine section, and an output shaft through which power is transferred. A turboprop engine may also apply. In addition, although the engine10is described herein for flight applications, it should be understood that other uses, such as industrial or the like, may apply. The engine10may include one or more variable geometry mechanisms (VGMs) which may assist in guiding airflow through the engine10. In some embodiments, the VGMs consist of one or more variable guide vanes (VGVs), which may be one of inlet compressor guide vanes for directing air into the compressor section14, outlet guide vanes for directing air out of the compressor section14, variable stator vanes for directing incoming air into rotor blades of the engine10, and/or one or more of variable nozzles, variable bleed-off valves, and the like. One or more of the above-mentioned VGMs may be modulated during the engine starting procedure. Control of the operation of the engine10can be effected by one or more control systems, for example an engine controller100. The engine controller100can modulate a fuel flow rate provided to the engine10via a fuel control unit, the position and/or orientation of VGMs within the engine10, a bleed level of the engine10, and the like. The engine controller100may be configured to start the engine10, as will be described in more detail herein. In some embodiments, the starting procedure is applied inflight. The engine controller100has access to various measured and/or synthesized operating parameters, such as altitude, calibrated airspeed (VCAS), engine temperatures (i.e. Static ambient temperature (Tamb), T1-T5and inter-turbine temperature (ITT)), engine fan speed (N1), engine core speed (N2), time, fuel flow (Wf), etc. For the purposes of the present disclosure, “operating parameters” refer to any parameters relating to the engine and/or aircraft environment that may be used by the engine controller100to set and/or determine engine control parameters. “Engine control parameters” refer to parameters that are controlled, set, modified, and/or modulated by the engine controller100for starting the engine10. With reference toFIG.2, there is illustrated an example method200for starting a gas turbine engine, such as engine10. Generally, in a gas turbine engine, inlet air is compressed through the compressor section14, mixed with fuel in an inflammable proportion in the combustor16, and then contacted with an ignition source inside the combustor16to ignite the mixture, which will then continue to burn. Certain combustors are designed to minimize emissions of gas from the engine. One consequence of this is that it is more difficult for the flames to propagate around the combustor upon light-up to cause light-around. For the purposes of the present disclosure, “light-up” or “light-off” refers to an initial ignition inside the combustor; “light-around” refers to the initial ignition having spread or propagated all around the combustor, to force air flow through a nozzle towards the turbine section18, for complete ignition. “Complete ignition” refers to a durable combustion inside the combustor16. The method200is separated into a plurality of sequential, gated phases, whereby different parameters are acted on at each phase. Each phase is dependent on specific criteria using various parameters, such as but not limited to engine exit temperature (T5), N2, rate of change of N2(N2dot), time, fuel flow, VGMs position, fuel divider valve position, altitude, and VCAS. In some embodiments, one or more of fuel flow amount, fuel flow distribution (via a fuel divider valve), VGM positions, and ignition frequency is applied and/or modified in a predefined and/or adaptive manner throughout the starting procedure. At step202, a first phase of the startup is initiated upon receipt of a start request. The first phase comprises modifying a first set of engine control parameters to cause light-up. At step204, a second set of engine control parameters are modified in a second phase of the startup. In some embodiments, the second phase is initiated when light-up is detected, which effectively ends the first phase. Alternatively, the second phase may be initiated before light-up is detected, such that there may be a small overlap between the first phase and the second phase. The second phase comprises setting conditions for light-around by modifying a second set of engine control parameters. At step206, a third set of engine control parameters are modified in a third phase of the startup. In some embodiments, the third phase is initiated when the light-around conditions are met, which effectively ends the second phase. Alternatively, the third phase may be initiated before the light-around conditions are fully met, such that there may be a small overlap between the second phase and the third phase. The third phase comprises modifying the third set of engine control parameters to propagate a flame around the combustor and cause complete ignition. In some embodiments, at step208, a fourth set of engine control parameters are modified in a fourth phase of the startup. In some embodiments, the fourth phase is initiated when compete ignition is detected, which effectively ends the third phase. Alternatively, the fourth phase may be initiated before complete ignition is detected, such that there may be a small overlap between the third phase and the fourth phase. The fourth set of engine control parameters are modified to transition towards a closed loop fuel control. After the fourth phase, the engine is ready for acceleration. A specific and non-limiting example will be presented with reference toFIGS.3A-3DandFIG.4.FIGS.3A-3Dare example embodiments of steps202,204,206, and208, respectively, of the method200.FIG.4is a graph illustrating an example scheduling of fuel flow, FDV, VGMs, and ignitor frequency for each phase. Referring toFIG.3A, a start request is received at step302. At step304, the VGMs are transitioned from a windmilling position to an ignition position. A windmilling position refers to a position allowing the optimum high spool rotating speed in preparation for in-air relight. An ignition position refers to a position allowing the optimum amount of air in the combustor for ignition. At step306, the fuel flow is set to an optimal amount for ignition based on operating parameters A1. In some embodiments, the operating parameters A1are altitude, VCAS, ITT and Tamb. The objective is to use a minimum number of parameters in order to set an optimum condition for ignition, while preventing stall on light-up. Therefore, any parameter affecting compressor stall margin or combustion quality can be used, such as fuel temperature, combustion chamber pressure, Mach number, N2(high spool speed), time since shutdown, etc. An adaptive fuel flow is used to set the fuel flow at step306, whereby fuel flow is increased by a predefined amount at predefined time intervals until light-up is detected. Other forms of adaptive fuel flow may also apply depending on practical implementations. At step308, an ignition frequency is set based on operating parameters A2, which may be for example altitude and VCAS. Other parameters may also be used, such as but not limited to fuel temperature, combustion chamber pressure, Mach number, N2(high spool speed), and time since shutdown. In some embodiments, the parameters used are related to a thermal state of the engine, since hot engines are less likely to require faster ignitor spark rates to ignite. Generally, the ignition frequency is set for a predefined amount of time, in accordance with ignitor system capabilities. Steps304-308are not necessarily performed sequentially. Each one of step304,306,308is performed independently within the first phase of the start procedure in accordance with its own parameters, so as to cause light-up. Dependence between the steps304,306,308may occur due to common operating parameters being used to trigger certain engine control parameters. Referring toFIG.4, the first phase is shown to occur between times TO and T2. At time T0, the start request is received. At time T2, light-up is detected and the first phase ends. Fuel flow and VGM are modulated starting at time TO. At time T1, ignitor frequency is modulated. Time T1is also a trigger for applying the ignition fuel flow. After a predefined amount of time past T1, an adaptive logic will progressively increase fuel flow if ignition is not detected. The exact approach may vary as a function of various factors and/or parameters. Referring toFIG.3B, the second phase is initiated once light-up is detected, in order to set conditions for light-around. Various criteria may be used to detect light-up, such as a change in engine exit temperature (ΔT5), N2, N2dot, ΔN2dot, and time. Other criteria may also apply. At step310, the adaptive fuel flow ends and the fuel flow amount is held constant. At step312, the ignitor frequency is pulled back after a certain amount of time to preserve ignitor life. Step310is triggered as soon as the second phase is initiated. Step312is triggered during the second phase, as a function of time. Referring toFIG.4, the second phase is shown to occur between times T2and T4. Fuel flow is held constant the entire duration of the second phase. The ignitor frequency changes at T3, with time being a trigger criteria. Referring toFIG.3C, the third phase is initiated when the light-around conditions are met. This phase may also be called light-around initiation. Various criteria may be used to determine that light-around conditions have been met, such as time, ΔT5, N2, and N2dot. Other criteria may also apply. At step314, the FDV position may, for example, be transitioned from an unequalized position to an equalized position, based on operating parameters A3. Placing the FDV in an equalized position will change the fuel flow distribution between the primary and secondary fuel nozzles and ease propagation of the flame all around the combustor. Other examples for positioning the FDV include maintaining an equalized position, maintaining an unequalized position, and transitioning from an equalized to an unequalized position. In some embodiments, the operating parameters A3are altitude and VCAS. In other embodiments, the operating parameters A3also include ITT and time since shutdown. Parameters related to the engine thermal state are considered since a hot engine may not require a transition to the FDV in order to propagate the flame around the combustor. Referring toFIG.4, the third phase is shown to occur between times T4and T5. Fuel flow, VGM position, and ignitor frequency are shown to remain constant during the third phase. Referring toFIG.3D, the fourth phase is initiated when complete ignition is detected. The fourth phase allows for a transition to closed loop fuel control and to compressor acceleration with surge protection. Various criteria may be used to determine that complete ignition has occurred, such as time, ΔT5, N2, and ΔN2dot. Other criteria may also apply. At step316, fuel flow is reduced based on operating parameters A4. Reduction of fuel flow may be done to minimize a risk of stalling and exceeding engine temperature limits while still allowing for stable combustion and engine acceleration. In some embodiments, the operating parameters A4are altitude, VCAS, and ambient temperature. Any parameter affecting stable combustion and compressor stall margin may be used in various combinations. In addition, the rate at which the fuel flow is reduced may be based on operating parameters A5, such as altitude, VCAS, and other parameters affecting stable combustion and compressor stall margin. At step318, VGMs are moved from the ignition position to an engine acceleration position based on time, N2, N2dot, and/or others. An engine acceleration position refers to a position allowing the optimum high spool compressor stall margin for a stall free acceleration. Referring toFIG.4, the fourth phase is shown to occur between times T5and T7. Fuel flow is reduced to a fixed, predefined value. The VGMs are moved at time T6. After time T7, a closed loop fuel flow control approach takes over as the engine has successfully started. Optimal conditions for acceleration are considered achieved. The engine will accelerate to idle at a suitable rate. FIG.5is an example embodiment of a computing device500for implementing parts or all of the method200described above. The computing device500comprises a processing unit502and a memory504which has stored therein computer-executable instructions506. The processing unit502may comprise any suitable devices configured to cause a series of steps to be performed such that instructions506, when executed by the computing device500or other programmable apparatus, may cause the functions/acts/steps specified in the method200described herein to be executed. The processing unit502may comprise, for example, any type of general-purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, a CPU, an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, other suitably programmed or programmable logic circuits, or any combination thereof. The memory504may comprise any suitable known or other machine-readable storage medium. The memory504may comprise non-transitory computer readable storage medium, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. The memory504may include a suitable combination of any type of computer memory that is located either internally or externally to device, for example random-access memory (RAM), read-only memory (ROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or the like. Memory504may comprise any storage means (e.g., devices) suitable for retrievably storing machine-readable instructions506executable by processing unit502. It should be noted that the computing device500may be implemented as part of a FADEC or other similar device, including an electronic engine control (EEC), engine control unit (EUC), engine electronic control system (EECS), an Aircraft Avionics System, and the like. In addition, it should be noted that the techniques described herein can be performed by a computing device500substantially in real-time. The methods and systems for starting a gas turbine engine as described herein may be implemented in a high level procedural or object oriented programming or scripting language, or a combination thereof, to communicate with or assist in the operation of a computer system, for example the computing device500. Alternatively, the methods and systems for starting a gas turbine engine may be implemented in assembly or machine language. The language may be a compiled or interpreted language. Program code for implementing the methods and systems for starting a gas turbine engine may be stored on a storage media or a device, for example a ROM, a magnetic disk, an optical disc, a flash drive, or any other suitable storage media or device. The program code may be readable by a general or special-purpose programmable computer for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein. Embodiments of the methods and systems for starting a gas turbine engine may also be considered to be implemented by way of a non-transitory computer-readable storage medium having a computer program stored thereon. The computer program may comprise computer-readable instructions which cause a computer, or more specifically the processing unit502of the computing device500, to operate in a specific and predefined manner to perform the functions described herein. Computer-executable instructions may be in many forms, including program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types. Typically the functionality of the program modules may be combined or distributed as desired in various embodiments. The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure. For example, it will be understood that different engine control parameters may be modulated, based on different operating parameters. A different number of phases may also apply, and the criteria for transitioning from one phase to another may differ and be adapted to different engine applications. Various aspects of the methods and systems for starting a gas turbine engine may be used alone, in combination, or in a variety of arrangements not specifically discussed in the embodiments described in the foregoing and is therefore not limited in its application to the details and arrangement of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments. The scope of the following claims should not be limited by the embodiments set forth in the examples, but should be given the broadest reasonable interpretation consistent with the description as a whole. | 19,058 |
11859556 | DETAILED DESCRIPTION Aspects of the disclosure described herein are directed to a turbine engine with an air turbine starter that includes a first bearing assembly configured to rotatably support a drive shaft or turbine member of the air turbine starter. A lubricant passageway provides lubricant to an outlet adjacent a gear operably coupled to the turbine member for rotation the gear. The gear can direct lubricant towards the first bearing assembly. Alternatively, a passageway can provide lubrication to a hollow stationary structure that includes at least one member can lift or direct lubricant toward the first bearing assembly. For purposes of illustration, the present disclosure will be described with respect to an air turbine starter for an aircraft turbine engine. For example, the disclosure can have applicability in other vehicles or engines, and can be used to provide benefits in industrial, commercial, and residential applications as further described inFIG.8. As used herein, the term “upstream” refers to a direction that is opposite the fluid flow direction, and the term “downstream” refers to a direction that is in the same direction as the fluid flow. The term “fore” or “forward” means in front of something and “aft” or “rearward” means behind something. For example, when used in terms of fluid flow, fore/forward can mean upstream and aft/rearward can mean downstream. Additionally, as used herein, the terms “radial” or “radially” refer to a direction away from a common center. For example, in the overall context of a turbine engine, radial refers to a direction along a ray extending between a center longitudinal axis of the engine and an outer engine circumference. Furthermore, as used herein, the term “set” or a “set” of elements can be any number of elements, including only one. All directional references (e.g., radial, axial, proximal, distal, upper, lower, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, upstream, downstream, forward, aft, etc.) are only used for identification purposes to aid the reader's understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of aspects of the disclosure described herein. Connection references (e.g., attached, coupled, secured, fastened, connected, and joined) are to be construed broadly and can include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to one another. The exemplary drawings are for purposes of illustration only and the dimensions, positions, order and relative sizes reflected in the drawings attached hereto can vary. Referring toFIG.1, an air turbine starter motor or air turbine starter10is coupled to an accessory gear box (AGB)12, also known as a transmission housing, and together are schematically illustrated as being mounted to a turbine engine14such as a gas turbine engine. This assembly is commonly referred to as an Integrated Starter/Generator Gearbox (ISGB). The turbine engine14comprises an air intake with a fan16that supplies air to a high-pressure compression region18. The air intake with a fan16and the high-pressure compression region collectively are known as the ‘cold section’ of the turbine engine14upstream of the combustion. The high-pressure compression region18provides a combustion chamber20with high pressure air. In the combustion chamber, the high-pressure air is mixed with fuel and combusted. The hot and pressurized combusted gas passes through a high-pressure turbine region22and a low-pressure turbine region24before exhausting from the turbine engine14. As the pressurized gases pass through the high-pressure turbine (not shown) of the high-pressure turbine region22and the low-pressure turbine (not shown) of the low-pressure turbine region24, the turbines extract rotational energy from the flow of the gases passing through the turbine engine14. The high-pressure turbine of the high-pressure turbine region22can be coupled to the compression mechanism (not shown) of the high-pressure compression region18by way of a shaft to power the compression mechanism. The low-pressure turbine can be coupled to the fan16of the air intake by way of a shaft to power the fan16. The AGB12is coupled to the turbine engine14at either the high pressure or low-pressure turbine region22,24by way of a mechanical power take-off26. The mechanical power take-off26contains multiple gears and means for mechanical coupling of the AGB12to the turbine engine14. Under normal operating conditions, the mechanical power take-off26translates power from the turbine engine14to the AGB12to power accessories of the aircraft for example but not limited to fuel pumps, electrical systems, and cabin environment controls. The air turbine starter10can be mounted on the outside of either the air intake region containing the fan16or on the core near the high-pressure compression region18. FIG.2is a schematic cross section of an exemplary air turbine starter10that can be included inFIG.1. Generally, the air turbine starter10includes a housing30defining an interior31and an exterior33of the housing30. An inlet32and an outlet34can also be defined by the housing30. A flow path36through the interior31is illustrated schematically with arrows. The flow path36extends between the inlet32and the outlet34for communicating a flow of fluid, including, but not limited to gas, compressed air, or the like, there through. In one non-limiting example, the fluid is air, such as pressurized air, that is supplied from a pressurized air source, including but not limited to, a ground-operating air cart, an auxiliary power unit, or a cross-bleed start from an engine already operating. The housing30can be formed in any suitable manner including, but not limited to, that it can be made up of two or more parts that are joined or otherwise coupled together or can be integrally formed as a single piece. A stator38can be included in the flow path36. The stator38can couple to or be formed as part of the housing30and include permeable portions40. The permeable portions40allow air in the flow path36to pass from the inlet32, through the stator38and to a turbine member42. The turbine member42can be journaled within the interior31of the housing30. The turbine member42can be disposed within the flow path36for rotatably extracting mechanical power from the flow of gas along the flow path36. The turbine member42can include a rotor portion44. A drive shaft50is coupled to the rotating turbine member42so that the drive shaft50can provide a rotational output. An output gear assembly52coupled to the drive shaft50allows for the transfer of mechanical power from the turbine member42to the output gear assembly52via the rotational output of the drive shaft50. The turbine member42, the drive shaft50, or a portion of the output gear assembly52can rotate about an axis of rotation54. The output gear assembly52can be or include a gear train56. An output shaft60can be operably coupled to the turbine member42via the gear assembly52including the gear train56. It is contemplated that the output gear assembly52can include an output gear62. A first bearing assembly64rotatably supports the drive shaft50. Optionally, a second bearing assembly66can rotatably support the drive shaft50or the output shaft60. The second bearing assembly66can be located downstream of the first bearing assembly64. By way of non-limiting example, the second bearing assembly66can be provided adjacent the gear train56or the gear assembly52. A stationary member72including a body74can be included within an interior formed by the housing30. The stationary member72can be formed with or coupled to the housing30, or the stator38, or any other suitable portion of the air turbine starter10. In the illustrated example, the stationary member72is illustrated as having a separate body74aas well as the portion74b. However, it will be understood that only a single unitary body can be utilized or the portion74bcould be utilized alone. It is contemplated that at least a portion of the stationary member72can form, by way of non-limiting example, a portion of a bearing housing of the first bearing assembly64. A bearing cavity78can be formed or defined by at least a portion of the body74and receive the first bearing assembly64therein. In this manner, the first bearing assembly64is located radially between a portion of the stationary member72and the drive shaft50. At least one bearing80, included in the first bearing assembly64, can be located in the bearing cavity78. A passage or lubricant passageway82can extend or traverse from an exterior84of the body74of the stationary structure or stationary member72to the bearing cavity78. In this manner, the lubricant passageway82extends, at least in part, in the radial direction. It is contemplated that the lubricant passageway82extends in the inward radial direction as illustrated by lubricant flow arrow85. The lubricant passageway82can couple an oil inlet86, provided at the exterior84of the body74, to an oil outlet88, provided at the bearing cavity78. The inlet86can have a radial distance measured from the axis of rotation54that is greater than the radial distance measured from the axis of rotation to the outlet88. The inlet86of the lubricant passageway82can couple to a conduit or be open to a chamber or cavity at the exterior84of the body74so that lubricant is received at the inlet86. For example, splash oil can be received on an upper exterior portion79of the stationary member72to form the lubricant received at the inlet86. A gear90can be axially located between the first bearing assembly64and the gear assembly52. The gear90is radially located between the drive shaft50and the stationary member72and located adjacent to the outlet88of the lubricant passageway82. The gear90is positioned and configured to direct lubricant from the outlet88towards the first bearing assembly64. The gear90operably couples to the drive shaft50. The gear90can be driven by the drive shaft50and rotate with the drive shaft50about the axis of rotation54. No portion of the gear90operably couples to another gear. That is, the gear90is separate, spaced, or otherwise operably independent of the gear train56and the gear assembly52. The gear90, by way of non-limiting example, can be a bevel gear.FIG.3illustrates an example of the gear90having a gear body92and a plurality of helical teeth94that protrude from the gear body92. The gear body92and the plurality of helical teeth94can be unitarily formed. The plurality of helical teeth94can be inclined at an angle with respect to the axis of rotation54. One non-limiting example of inclination with respect to the axis of rotation54can be a radial inclination. That is, the plurality of helical teeth94are at a radial angle greater than zero with respect to the axis of rotation54. This can be illustrated by measuring an upstream outer diameter96and a downstream outer diameter98of the gear body92. If the first bearing assembly64is upstream of the gear90, as illustrated, the upstream outer diameter96is less than the downstream outer diameter98. However, it is contemplated that based on the location of the first bearing assembly64relative to the gear90, that the upstream outer diameter96can be greater than or equal to the downstream outer diameter98. Another non-limiting example of inclination with respect to the axis of rotation54is an axial inclination. That is, a peak line100of at least one of the plurality of helical teeth94is not parallel in an axial direction to the axis of rotation54. The peak line100can be drawn axially across the entirety of each helical tooth94at a point that radially protrudes the greatest distance from the gear body92. In operation, and referring back toFIGS.2and3, compressed air is provided at the inlet32of the air turbine starter10. The compressed air is directed by the stator38through the flow path36. The turbine member42in the flow path36rotates in response to the compressed air flow. The turbine member42is operably coupled to the drive shaft50, which provides rotational output that will result in starting the turbine engine14. Lubricant via normal operation of the air turbine starter10is delivered, splashed, or otherwise transferred to the inlet86of the lubricant passageway82. The lubricant flows through the lubricant passageway82to the outlet88. The gear90, located adjacent to the outlet88, receives the lubrication which flows or splashes against the gear body92. In the illustrated example, the plurality of helical teeth94are inclined away from the first bearing assembly64such that lubricant travels downwards towards the first bearing assembly64. The drive shaft50rotates the gear90. As the drive shaft50rotates, the gear90reaches a position in which the lubricant flows from between the plurality of helical teeth94towards the first bearing assembly64. The lubricant delivered to the first bearing assembly64can cool and lubricate the first bearing assembly64. FIG.4is another example of a schematic cross section of an air turbine starter110that can be used with the turbine engine14. The air turbine starter110is similar to the air turbine starter10, therefore, like parts will be identified with like numerals increased by 100, with it being understood that the description of the like parts of the air turbine starter10applies to the air turbine starter110, unless otherwise noted. Generally, the air turbine starter110includes a housing130defining an interior131and an exterior133of the housing130. An inlet132and an outlet134can also be defined by the housing130. The flow path136through the interior131is illustrated schematically with arrows. The flow path136extends between the inlet132and the outlet134for communicating a flow of fluid, including, but not limited to gas, compressed air, or the like, there through. A stator138can be included in the flow path136. The stator138can couple to or be formed as part of the housing130and include permeable portions140. The permeable portions140allow air in the flow path136to pass from the inlet132, through the stator138and to a turbine member142. The turbine member142can be journaled within the interior131of the housing130. The turbine member142can be disposed within the flow path136for rotatably extracting mechanical power from the flow of gas along the flow path136. The turbine member142can include a rotor portion144. A drive shaft150is coupled to the rotating turbine member142so that the drive shaft150can provide a rotational output. A gear assembly152coupled to the drive shaft150allows for the transfer of mechanical power from the turbine member142to the gear assembly152via the rotational output of the drive shaft150. The turbine member142, the drive shaft150, or a portion of the gear assembly152can rotate about an axis of rotation154. The gear assembly152can be or include a gear train156. An output shaft160can be operably coupled to the turbine member142via the gear assembly152or the gear train156. It is contemplated that the gear assembly152or the gear train156can include an output gear162. A first bearing assembly164rotatably supports the drive shaft150. Optionally, a second bearing assembly166can rotatably support the drive shaft150or the output shaft160. The second bearing assembly166can be located downstream of the first bearing assembly164. By way of non-limiting example, the second bearing assembly166can be included in the gear train156or the gear assembly152. A hollow stationary structure or hollow stationary member172can be formed with or coupled to the housing130or the stator138. The first bearing assembly164is located radially between a portion of the hollow stationary member172and the drive shaft150. It is contemplated that at least a portion of the hollow stationary member172can be, by way of non-limiting example, a portion of a bearing housing. The hollow stationary member172includes a body174bthat at least in part defines a bearing cavity178. The bearing cavity178include the first bearing assembly164. At least one bearing180can be located in the bearing cavity178. While illustrated as a separate piece, the body174bcan be unitarily formed with the hollow stationary member172. A passage or passageway182can extend through extending through at least a portion of the hollow stationary member172. An oil inlet186for splash oil can be defined at an upper portion187of the hollow stationary member172. An oil outlet188of the passageway182can be defined by at a lower portion189of the hollow stationary member172. The passageway182can extend circumferentially through at least a portion of the hollow stationary member172from the inlet186to the outlet188. While this is not shown in its entirety, the passageway182essentially extends into the page ofFIG.4at the inlet186and returns towards the reader at the outlet188. That is, the passageway182at least partially circumscribes the drive shaft150so that lubricant flows in a circumferential direction about the axis of rotation154through the passageway182from the inlet186to the outlet188. A basin191can fluidly connect with the outlet188. The basin191can, at least in part, be defined by the lower portion189of the hollow stationary member172. The basin191can be adjacent to or otherwise fluidly connected to the bearing cavity178. The basin191can also be formed by at least one member located within the bearing cavity178and configured to direct lubricant in the basin191towards the first bearing assembly164. For example, a first part201can be radially received adjacent the hollow stationary member172. At a lower end the first part201includes a lower surface193forming a portion of the basin191. The lower surface193declines towards the first bearing assembly164, forming the at least one member configured to direct lubricant in the basin191to the first bearing assembly164. Alternatively, it is contemplated that the bearing cavity178itself can be shaped to form such a sloping basin. Additionally, or alternatively, at least one seal197can extend from the first part201. The at least one seal197can be located at a first end195of the basin191. The at least one seal197can be axially located between the bearing cavity178and the gear assembly152or gear train156. A labyrinth seal having a set of projections199can, at least in part, define the at one seal197. It is contemplated that the hollow stationary member172can include one or more inner radial components, such as but not limited to inner radial component173that can be coupled to or formed with the hollow stationary member172. The inner radial component173can in part define the passageway182, the inlet186, the outlet188, the basin191, or the at least one seal197. In operation, the passageway182is fluidly coupled to receive splash oil on an upper exterior portion179of the hollow stationary member172. That is, lubricant is delivered, splashed, or otherwise transferred to the inlet186of the passageway182. The lubricant flows from the inlet186, through the passageway182, and exits through the outlet188. The lubricant can then flow or accumulate in the basin191in the lower portion189of the hollow stationary member172. The basin191includes the lower surface193slanted or angled so that the lubricant is directed into the first bearing assembly164. The seal197, that can be a labyrinth seal, can includes a set of projections199to further discourage the lubricant from leaving the basin191from the rear and thus encourage the lubricant to enter the first bearing assembly164. The lubricant delivered to the first bearing assembly164can cool and lubricate the first bearing assembly164, allowing the drive shaft150to provide rotational output that will result in starting the turbine engine14. FIG.5is yet another example of a schematic cross section of an air turbine starter210that can be used with the turbine engine14. The air turbine starter210is similar to the air turbine starter10,110therefore, like parts will be identified with like numerals further increased by 100, with it being understood that the description of the like parts of the air turbine starter10,110applies to the air turbine starter210, unless otherwise noted. Generally, the air turbine starter210includes a housing230defining an interior231and an exterior233of the housing230. An inlet232and an outlet234can also be defined by the housing230. A flow path236through the interior231is illustrated schematically with arrows. The flow path236extends between the inlet232and the outlet234for communicating a flow of fluid, including, but not limited to gas, compressed air, or the like, there through. In one non-limiting example, the fluid is air, such as pressurized air, that is supplied from a pressurized air source, including but not limited to, a ground-operating air cart, an auxiliary power unit, or a cross-bleed start from an engine already operating. The housing230can be formed in any suitable manner including, but not limited to, that it can be made up of two or more parts that are joined or otherwise coupled together or can be integrally formed as a single piece. A stator238can be included in the flow path236. The stator238can couple to or be formed as part of the housing230and include permeable portions240. The permeable portions240allow air in the flow path236to pass from the inlet232, through the stator238and to a turbine member242. The turbine member242can be journaled within the interior231of the housing230. The turbine member242can be disposed within the flow path236for rotatably extracting mechanical power from the flow of gas along the flow path236. The turbine member242can include a rotor portion244. A drive shaft250is coupled to the rotating turbine member242so that the drive shaft250can provide a rotational output. A gear assembly252coupled to the drive shaft250allows for the transfer of mechanical power from the turbine member242to the gear assembly252via the rotational output of the drive shaft250. The turbine member242, the drive shaft250, or a portion of the gear assembly252can rotate about an axis of rotation254. The gear assembly252can be or include a gear train256. An output shaft260can be operably coupled to the turbine member242via the gear assembly252or the gear train256. It is contemplated that the gear assembly252or the gear train256can include an output gear262. A first bearing assembly264rotatably supports the drive shaft250. Optionally, a second bearing assembly266can rotatably support the drive shaft250or the output shaft260. The second bearing assembly266can be located downstream of the first bearing assembly264. By way of non-limiting example, the second bearing assembly266can be included in the gear train256or the gear assembly252. A hollow stationary member272can be formed with or coupled to the housing230or the stator238. The first bearing assembly264is located radially between a portion of the hollow stationary member272and the drive shaft250. It is contemplated that at least a portion of the hollow stationary member272can form a portion of a bearing housing. The hollow stationary member272can include a body274that is located radially within the hollow stationary member272and can, at least in part, define a bearing cavity278. The bearing cavity278include the first bearing assembly264. At least one bearing280can be located in the bearing cavity278. While illustrated as a separate piece, the body274can be unitarily formed with the hollow stationary member272. A passage or passageway282can extend through extending through at least a portion of the hollow stationary member272. An oil inlet286for splash oil can be defined at an upper portion287of the hollow stationary member272. An oil outlet288of the passageway282can be defined by at a lower portion289of the hollow stationary member272. The passageway282can extend circumferentially through at least a portion of the hollow stationary member272from the inlet286to the outlet288. A basin291can fluidly connect with the outlet288. The basin291can, at least in part, be defined by the lower portion289of the hollow stationary member272. The basin291can be adjacent to or otherwise fluidly connected to the bearing cavity278. At least one member is located within the bearing cavity278and configured to direct lubricant in the basin291towards the first bearing assembly264. The at least one member can, by way of non-limiting example, be a rotatable member265. The rotatable member265can be coupled to the drive shaft250, where the rotatable member265and the drive shaft250rotate together about the axis of rotation254. The rotatable member265can be a scoop wheel that can lift lubricant from the basin291as the rotatable member265rotates. At least one vane267is located on the scoop wheel or rotatable member265to direct fluid to at least one fluid outlet269laterally adjacent the at least one vane267. FIG.5further illustrates the rotatable member265or scoop wheel having vanes267. Lubricant flow arrow285illustrates the flow of lubricant into the rotatable member265and exiting via the at least one fluid outlet269as guided by the at least one vane267during rotational movement of the rotatable member265. Rear wall271seals the downstream side of the rotatable member265, ensuring the exit of the lubricant through the at least one fluid outlet269that is fluidly connected to the bearing cavity278. FIG.6is a cross section of the rotatable member265further illustrating the scoops or vanes267. The at least one vane267can include a scooping portion273that directs fluid from the basin291into the rotatable member265. A guiding portion275of the at least one vane267directs fluid as the rotatable member265rotates. The guiding portion275can define at least one void277capable of receiving fluid. The scooping portion275directs the fluid from the at least one void277to the bearing cavity278via the at least one fluid outlet269. While illustrated as having four vanes267, it is contemplated that any number of vanes or other methods of scooping fluid can be used in the rotatable member265. In operation, compressed air is provided at the inlet232of the air turbine starter210. The compressed air is directed by the stator238through the flow path236. The turbine member242in the flow path236rotates in response to the compressed air flow. The turbine member242is operably coupled to the drive shaft250. The passageway282is fluidly coupled to receive splash oil on an upper exterior portion279of the stationary member272. That is, lubricant is delivered, splashed, or otherwise transferred to the inlet286of the passageway282. The lubricant flows from the inlet286through the passageway282, exiting at the outlet288. The lubricant can then flow or accumulate in the basin291in the lower portion289of the hollow stationary member272. The lubricant in the basin291is scooped or otherwise lifted by the rotatable member265that is operably coupled and rotating with the drive shaft250. The at least one vane267includes the scooping portion273that directs fluid from the basin291into the at least one void277of rotatable member265defined by the guiding portion275(FIG.7) and the rear wall271. As the rotatable member265rotates, the lubricant is lifted upwards and spills out the at least one fluid outlet269. Upon exiting the rotatable member265at the at least one fluid outlet269, the lubricant flows into the bearing cavity278. The lubricant delivered to the first bearing assembly264can cool and lubricate the first bearing assembly264, allowing the drive shaft250to provide rotational output that will result in starting the turbine engine14. Many other possible examples and configurations in addition to those shown in the above figures are contemplated by the present disclosure. Additionally, the design and placement of the various components such as the AGB12or the air turbine starter10or components thereof can be rearranged such that a number of different configurations could be realized. FIG.8is a schematic illustration of the turbine engine14and starter10fromFIG.1, where the turbine engine14can be in a vehicle or structure300. The vehicle or structure300can be, by way of non-limiting example, a helicopter or other aircraft, a boat or other aquatic vehicle, or a car or other land vehicle. Further, the vehicle or structure300can be, but is not limited to, a marine power plant, a wind turbine, or a small power plant. It is further considered that the turbine engine14can be any engine using a turbine with the starter/generator10required by the vehicle or structure300. Benefits associated with aspects of the disclosure herein reduced temperatures in the first bearing assembly can lead to longer part life. Additionally, the reduced running temperature in the first bearing assembly can lead to an overall longer operational time for the air turbine starter. The reduced temperatures in the first bearing assembly can also allow for a faster rotation of the drive shaft. A faster rotation of the drive shaft increases the power output from the air turbine starter. This will allow smaller air turbine starters to provide the power needed to start a larger variety of turbine engines. The reduced temperatures in the first bearing assembly can also allow for a longer run time of the air turbine starter. A longer run time allows the turbine engine to attempt to start using the air turbine starter more than once before a cool-down cycle is performed. Further aspects of the invention are provided by the subject matter of the following clauses:1. An air turbine starter that includes a housing defining an exterior, an interior, an inlet, an outlet, and a flow path extending through the interior between the inlet and the outlet, a turbine member having a rotor portion journaled within the interior of the housing and disposed within the flow path, a drive shaft operably coupled with the turbine member, a stationary member having a body forming a bearing cavity, a first bearing assembly configured to rotatably support the drive shaft or turbine member, a lubricant passageway traversing from an exterior of the body of the stationary structure to the bearing cavity, and a gear located adjacent an outlet of the lubricant passageway and operably coupled to the turbine member for rotation therewith, the gear configured to direct lubricant towards the first bearing assembly.2. The air turbine starter of clause 1 wherein the lubricant passageway extends, at least in part, in a radial direction.3. The air turbine starter of any preceding clause, further comprising a gear assembly operably coupling the turbine member and the drive shaft and separate from the gear located adjacent the outlet.4. The air turbine starter of any preceding clause wherein the gear assembly is a gear train including an output gear providing a driving force to an output shaft.5. The air turbine starter of any preceding clause wherein the gear includes a plurality of helical teeth that are not operably coupled to another gear.6. The air turbine starter of any preceding clause wherein the gear rotates about an axis of rotation and the plurality of helical teeth are inclined at an angle with respect to the axis of rotation.7. The air turbine starter of any preceding clause wherein the gear comprises a bevel gear mounted to the drive shaft.8. The air turbine starter of any preceding clause, further comprising a second bearing assembly configured to rotatably support the drive shaft downstream of the first bearing assembly.9. The air turbine assembly of any preceding clause wherein the lubricant passageway is fluidly coupled to receive splash oil on an upper exterior portion of the stationary member.10. An air turbine starter, including a housing defining an interior, a turbine member having a rotor portion journaled within the interior of the housing, a drive shaft operably coupled with the turbine member, a hollow stationary structure located within the housing and having a body defining a bearing cavity, a passage extending through at least a portion of the hollow stationary structure, the passage having an inlet for splash oil in at least an upper portion of the hollow stationary structure and a basin defined at a lower portion of the hollow stationary structure and wherein the basin is fluidly coupled to the bearing cavity, a first bearing assembly located within the bearing cavity, the first bearing assembly configured to rotatably support the drive shaft, and at least one member located within the bearing cavity and configured to direct lubricant in the basin towards the first bearing assembly.11. The air turbine starter of any preceding clause wherein the passage extends circumferentially from the inlet located at an upper portion of the hollow stationary structure to an outlet located at the lower portion of the hollow stationary structure and wherein the outlet is fluidly coupled to the basin.12. The air turbine starter of any preceding clause, further comprising a seal at a first end of the basin, the seal located between the hollow stationary structure and the drive shaft.13. The air turbine starter of any preceding clause wherein the seal is a labyrinth seal having a set of projections.14. The air turbine starter of any preceding clause wherein a surface of the seal is declined towards the first bearing assembly and forms the at least one member.15. The air turbine starter of any preceding clause wherein the at least one member comprises a rotatable member located within the bearing cavity at least a portion of which is radially external of the first bearing assembly and wherein the rotatable member is configured to lift lubricant from the basin.16. The air turbine starter of any preceding clause wherein the rotatable member is a scoop wheel having a set of vanes.17. The air turbine starter of any preceding clause wherein the scoop wheel further comprises at least one fluid outlet laterally adjacent the set of vanes.18. The air turbine housing of any preceding clause wherein the fluid outlet is fluidly coupled to a void formed in the scoop wheel via the vane.19. The air turbine assembly of any preceding clause wherein the lubricant passageway is fluidly coupled to receive splash oil on an upper exterior portion of the stationary member to form the lubricant.20. The air turbine starter of any preceding clause, further comprising a second bearing assembly configured to rotatably support the drive shaft downstream of the first bearing assembly. This written description uses examples to describe aspects of the disclosure described herein, including the best mode, and also to enable any person skilled in the art to practice aspects of the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of aspects of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. | 35,562 |
11859557 | DETAILED DESCRIPTION With reference toFIGS.1and2, there is shown a generator drive disconnect device1of a generator2(shown in part) arranged to be driven by an aircraft engine (shown schematically as item3inFIG.1). The generator drive disconnect device1can be comprised in a generator2, arranged to be driven by an aircraft engine3. The disconnect device1comprises drive transfer means100, a disconnect mechanism200and a latch mechanism300. The disconnect mechanism200is configured to move the drive transfer means100from a connected configuration, as shown inFIG.1, to a disconnected configuration, as shown inFIG.2. The drive transfer means100comprises an input shaft110and an output shaft120. The input and output shafts110,120are coaxially aligned about input shaft axis A. The input shaft110is coupled to a drive shaft410from the engine3and the output shaft120is coupled to a rotor shaft420of the generator2by splines121extending circumferentially around its exterior surface such that the output shaft120is axially moveable relative to the rotor shaft420. In the connected configuration of the drive transfer means100, the input shaft110and the output shaft120are rotated together, at the same rotational speed. Between the input and output shafts110,120, there is provided a separable drive transfer device130which is moveable between connected and disconnected configurations. The separable drive transfer device130can be any suitable device by which rotary movement of the input shaft110is selectively transferred to the output shaft120. In this example, the separable drive transfer device130is a clutch comprising a first plate131coupled to the input shaft110, a second plate132coupled to the output shaft120, and a spring133which urges the output shaft120and the second plate132towards the input shaft110and the first plate131. Friction between the first plate131and the second plate132, in the case of a friction based clutch mechanism, and/or the meshing of teeth of dogs or face gears of the respective first and second plates in certain embodiments, couples a rotational driving torque between the rotor shaft420and the gearbox drive shaft410, allowing the gearbox drive shaft to drive the rotor shaft (or vice versa, which can allow the generator to function as a starter-generator if required). Operation of the drive transfer device130is controlled by the disconnect mechanism200. The disconnect mechanism200is arranged to move the drive transfer means between its connected and disconnected configurations. In this example, the disconnect mechanism is engageable with the second plate132of the drive transfer device130to move the output shaft120axially away from the input shaft110and thereby disengage the drive transfer device130by moving it to the disconnected configuration. In other examples, the disconnect mechanism may engage with one or more other components of the drive transfer device130, for example axially moveable input or output shafts or the first plate131, in order to move the drive transfer means between its connected and disconnected configurations. The disconnect mechanism200comprises an actuator210having a piston211which is moveable within a chamber212between a first position, as shown inFIG.1, and a second position, as shown inFIG.2. In this example, the piston211and chamber212are annular and arranged around the drive transfer device130for improved packaging of the overall disconnect mechanism. The actuator may be any suitable type of actuator, for example a pneumatic actuator, a hydraulic actuator, or an electrically driven actuator, such as a solenoid. In this example, the actuator is a pneumatic actuator and the disconnect mechanism200also includes a gas storage means (not shown) which is connected to the chamber212by a pipe (not shown). When actuation of the disconnect device is required, compressed gas is transferred by a gas release means, such as a valve or a moveable puncture device for rupturing a seal of the gas storage means, from the gas storage means to the chamber212via the pipe to move the piston211from the first position to the second position. The force from the compressed gas exceeds the force from the spring133of the clutch130thereby moving the drive transfer means130to the disconnected configuration by driving the second plate132away from the first plate131. The actuator has an outer surface on which a recess213is formed and with which the latch mechanism300interacts to hold the actuator in the second position, and therefore hold the drive transfer device130, and the disconnect device as a whole, in the disconnected configuration. The latch mechanism300includes a support structure310, a latch member in the form of a latch plate320, and a biasing mechanism in the form of a spring assembly330. The support structure310is fixed in position relative to the rest of the disconnect device1and forms a base by which the rest of the latch mechanism300is supported. The latch plate320is moveable between a retracted position, as shown inFIG.1, and an extended position, as shown inFIG.2, in which movement of the actuator towards the first position from the second position is prevented by the latch plate320, as discussed in more detail below. The spring assembly330is configured to apply a biasing force to the latch plate320to bias it towards the extended position. The spring assembly330is also configured to apply to the latch plate320a reaction force to resist movement of the latch plate320towards the retracted position. The reaction force has a magnitude which increases as a function of the distance of the latch member320from the retracted position. Thus, as the latch plate320moves towards the extended position, the magnitude of the reaction force increases. FIGS.3to5show the latch mechanism300according to the present invention in which the support structure310, latch member320, and biasing mechanism are shown in more detail. The support structure310comprises a support frame311and a mounting portion312by which the support structure310is fixed in position relative to other fixed components of the disconnect device1. The support frame311has two support arms extending along either side of the latch member320by which the latch member320is supported. The support arms include a pair of support slots313, each support slot313extending through one of the support arms on either side of the latch member320. The support slots313define a bearing surface314forming part of a cam follower mechanism of the latch mechanism300. The support arms of the support frame311also include a pair of pivot holes315through which a pivot pin316extends to rotatably mount the latch member320on the support structure310. The mounting portion312may be fixed in position by any suitable fastener. In this example, the mounting portion312includes bolt holes317extending through a mounting plate318by which the support structure310can be fixed in position to the generator housing using threaded bolts. The latch plate320includes a latch portion321having a latch surface322by which the disconnect mechanism can be held in place when the latch plate320is in the extended position to retain the drive transfer means in a disconnected configuration. The latch plate320also includes a curved latch slot323defining a curved cam surface324by which forces from the biasing mechanism330are applied to the latch plate320. The latch slot323forms part of the cam follower mechanism of the latch mechanism300. The latch plate320also includes a latch pivot hole325, through which the pivot pin316extends. As with the support structure310, the latch plate320may further include one or more cut-out portions325by which the overall weight of the latch mechanism can be reduced. The biasing mechanism330includes a biasing means331, a sprung block332, a sprung pin333, a pair of link plates334, and a drive pin335. The biasing means generates a biasing force in a biasing direction. In this example, the biasing means is a coil spring which is mounted at one of its ends to the support structure310and is connected at its other end to the sprung block332so that the biasing force is applied to the sprung block332in a biasing direction away from the disconnect mechanism200. The sprung pin333extends through the spring block332and is connected at each of its ends to a first end of the link plates334. In a similar manner, the drive pin335is connected at each of its ends to the link plates334, at the opposite end of the link plates334to the sprung pin333. In this manner, the drive pin335is biased away from the disconnect mechanism200by the biasing means331via the link plates334and the sprung spin333. In this example, the sprung pin333and the drive pin335each extend through holes in the link plates335and are held in place by circlips336. The drive pin335extends through the support slots313in the support arms of the support frame311and is moveable within the support slots313in contact with the bearing surface314defined by each support slot313. The drive pin335also extends through the latch slot323in the latch member320and is moveable within the latch slot323in contact with the cam surface324defined by the latch slot323. In this manner, movement of the drive pin335is constrained by the support slots313and the latch slot323. The drive pin335is biased away from the disconnect mechanism200by the spring331and is constrained to move relative to the support structure310along the direction of the bearing surfaces314of the support slots313. In this example, the bearing surfaces314are linear and substantially parallel with the spring axis of the spring331. As such, the drive pin335is biased by the spring331to move along a path which is parallel with the biasing direction. This can maximise the efficiency with which the biasing force is transferred to the drive pin335. Together, the cam surface324and the drive pin form a cam follower mechanism. FIG.4includes a schematic illustration of the forces applied by the biasing mechanism to the latch mechanism, when the latch member320is in the retracted position. In the retracted position, the drive pin335(i.e. the follower) is in contact with a first portion of the cam surface324(i.e. the cam) which extends at a first angle of A1relative to the biasing direction and at a third angle of B1relative to the bearing surface314. In this example, the bearing surface314adjacent to the first portion of the cam surface324is parallel with the biasing direction and so the first and third angles, A1, B1are the same, although this might not be the case in other embodiments. The biasing means applies a first biasing force of FB1to the drive pin335, which in turn applies a first latching force FL1perpendicular to the first portion of the cam surface324to bias the latch member320towards the extended position. As can be seen, the first latching force FL1is broadly equal to FB1sin(A1). As the latch member320rotates towards the extended position, the drive pin335moves along the support slot313and along the latch slot323to the position shown inFIG.5. In addition to biasing forces applied by the biasing means331to rotate the latch member320towards the extended position, the latch member320can also be subjected to retraction forces which will tend to rotate the latch member320towards the retracted position. Such retraction forces could be caused by acceleration, or operational forces caused by the disconnect mechanism, for example. For illustrative purposes, the retraction forces are shown as a single point load FR1exerted at the latch surface. The biasing mechanism is configured to resist these retraction forces by applying to the latch plate320a reaction force to resist movement of the latch member320towards the retracted position. As can be seen, in the retracted position, a first reaction force R1is exerted by the drive pin335on the latch member320perpendicularly to the first portion of the cam surface324. Since the drive pin335is prevented from moving away from the cam surface324, in order to rotate the latch member320in the retraction direction, the retraction force FR1must generate sufficient torque to overcome the first reaction force R1and thereby push the drive pin335away from the biasing spring331. The first reaction force R1has a magnitude which can be approximated by dividing the first biasing force FB1by sin(A1). In order to rotate the latch member320, the retraction force FR1must generate a force which opposes the first reaction force R1and exceeds it. When the latch member320is in the retracted position, it is beneficial for the reaction force to be relatively low so that the disconnect mechanism is not unduly hindered in moving from its first position to its second position to disconnect the drive transfer means. FIG.5includes a schematic illustration of the forces applied by the biasing mechanism to the latch mechanism, when the latch member320is in the extended position. In the extended position, the drive pin335(i.e. the follower) is in contact with a second portion of the cam surface324(i.e. the cam) which extends at a second angle of A2relative to the biasing direction and at a third angle of B2relative to the bearing surface314. In this example, the bearing surface314adjacent to the second portion of the cam surface324is parallel with the biasing direction and so the second and fourth angles, A2, B2are the same, although this might not be the case in other embodiments. As with the retracted position, the latch member320can also be subject to retraction forces which will tend to rotate the latch member320towards the retracted position. Again, for illustrative purposes, the retraction forces are shown as a single point load FR2exerted at the latch surface. The biasing mechanism is configured to resist these retraction forces by applying to the latch plate320a reaction force to resist movement of the latch member320towards the retracted position. As can be seen, in the extended position, a second reaction force R2is exerted by the drive pin335on the latch member320perpendicularly to the second portion of the cam surface324. Since the drive pin335is prevented from moving away from the cam surface324, the second retraction force FR2must generate sufficient torque to overcome the second reaction force R2and thereby push the drive pin335away from the biasing spring331in order to rotate the latch member320in the retraction direction. The second reaction force R2has a magnitude which can be approximated by dividing the second biasing force FB2by sin(A2). In order to rotate the latch member the retraction force R2must generate a force which opposes the first reaction force R1and exceeds it. When the latch member320is in the extended position, it is beneficial for the reaction force to be high so that the latch mechanism is not inadvertently de-latched from the disconnect mechanism by the retraction forces. For a linear coil spring, the magnitude of the biasing force decrease as the spring is displaced away from the compressed condition. Thus, the biasing force exerted by the biasing mechanism can be expected to be lower when the latch member320is in the extended position. In other words, generally, the first biasing force will be greater than the second biasing force. For conventional sprung latch systems this can be problematic, since the high spring rate required to generate sufficient resistance to de-latching in the extended position can result in excessively high forces being exerted by the latch on the actuator when the latch is in the retracted position. Conversely, the low spring rate required to avoid hindering the operation of the disconnect mechanism when the latch member320is in the retracted position can lead to insufficient resistance to de-latching in the extended position. This problem can be overcome by the disconnect device of the present invention. As can be seen inFIGS.4and5, despite the fact that the first biasing force FB1is greater than the second biasing force FB2, the second reaction force R2is far higher than the first reaction force R1. Consequently, the retraction force required to rotate the latch member in the retraction direction from the extended position is also far higher than the retraction force required to rotate the latch member320in the retraction direction from the retracted position. This is further illustrated inFIG.6, below. FIG.6is a chart illustrating reaction force as a function of latch member position. As can be seen, when the latch member320is in the retracted position (position “1” on the chart), the reaction force is relatively low. This means that the de-latching force required to move the latch member320in the retraction direction is also fairly low. Thus, movement of the disconnect mechanism is largely unhindered by the latch mechanism. However, as the latch member320moves towards the extended position (position “11” on the chart) the reaction force increases exponentially as a function of the distance of the latch member320from the extended position. This is because the angle of the cam surface324becomes shallower towards the extended position and tends towards the biasing direction and the orientation of the bearing surface. In fact, the curved shape of the latch slot means that the angle of the cam surface324could be arranged such that the cam surface324is parallel with the bearing surface and the biasing direction, or negative with respect to the bearing surface or the biasing direction, when the latch member is in the extended position. In such examples, the cam mechanism forms a mechanical or geometric lock when the latch member is in the extended position so that the latch mechanism could not be de-latched by any amount of de-latching force exerted on the latch member. To return the latch mechanism to the retracted position, a tool350can be inserted into an access port351in the disconnect device1to push on the sprung block332and compress the biasing means331, as shown inFIG.7. Operation In the following, the operation of the generator drive disconnect device shall be described with reference toFIGS.1to7. In the connected configuration of the drive transfer means130, shown inFIG.1, the clutch arrangements131and132of the drive transfer device130are engaged so that the input shaft110and the output shaft120are connected. In particular, the drive transfer device130is biased towards the output shaft120by the resilient member133, such that the clutch arrangements131and132are in meshing contact. Rotary drive input via the input shaft110is transferred from the drive shaft410to the drive transfer device130. The drive transfer device130, in turn, is connected to the output shaft120via the clutch arrangements131,132, and thus drives the output shaft at the same rotational speed as the input shaft110. The latch mechanism300is in the retracted position, with the latch surface of the latch member resting against the outer surface of the actuator of the disconnect mechanism. Although the latch member is biased towards its extended position, and therefore towards the actuator, the biasing force and the resulting friction forces are low enough that movement of the actuator is not hindered by the latch member. This is due to the arrangement of the cam surface324and the drive pin, as discussed above. If a fault condition, or other trigger condition, requires the generator to be disconnected, the disconnect mechanism200is actuated to separate the clutch arrangements131,132from each other. To this end, the piston211of the actuator is moved in the chamber212in the direction of the input shaft axis A, causing the output shaft120to move in the direction of the input shaft axis and away from the input shaft110. As the output shaft120is moved away from the input shaft110, the clutch arrangements131and132disengage, thereby mechanically decoupling the input shaft110from the output shaft120and thereby placing the disconnect device1in the disconnect configuration, as shown inFIG.2. In the disconnected configuration of the disconnect device1shown inFIG.2, the resilient member133(coil spring) is compressed and acts to restore the connected configuration shown inFIG.1. However, when the piston211reaches the end of its stroke in its second position, the latch surface of the latch member is received in the recess on the outer surface of the piston211. This prevents movement of the actuator and holds the disconnect device in the disconnected configuration. Furthermore, due to the position of the pivot, any lateral forces applied to the latch member by the actuator in the connecting direction will be in the extension direction of the latch member and further increase the security with which the disconnect device is held in the disconnect configuration by the latch mechanism. As such, it is not possible to transfer the drive transfer means back into its connected configuration while the latch member is in its extended position. If the condition requiring disconnection of the generator has been resolved, then the latch member can be rotated back to the retracted position by removing a bung352from an access port351in the disconnect device1and inserting a tool350in the access portion351to push the drive pin335away from the spring331and against the biasing force. The actuator can then be moved back to its first position and the latch member will be held in the retracted position in which the latch surface rests against the outer surface of the actuator. As will be appreciated, the new arrangement of the generator drive disconnect device according to the present invention provides a reliable and secure way of disconnecting the generator. Although the cam mechanism is illustrated as being formed by a cam surface on the latch member and a follower attached the biasing member, these components could be reversed so that the follower is connected to the latch member and the cam surface is formed as part of the biasing mechanism. Although the latch slot is described as curved, the latch slot could be formed of one or more linear portions. For example, the latch slot could be a V-shaped slot, or a simple linear slot at an angle to the bearing surface. Such a linear slot could still result in an increase in the resistance to retraction of the latch member towards the extended position as the angle of the cam surface will change relative to the bearing surface as the latch member rotates. | 22,484 |
11859558 | The elements having the same functions in the different implementations have the same references in the figures. DETAILED DESCRIPTION OF THE INVENTION FIGS.1to3show a turbomachine10, comprising a driving device20according to the invention. The turbomachine10comprises an accessory gear box12which is configured to be driven by an engine shaft. The accessory gear box12may comprise a plurality of gear trains connected to output shafts for driving various equipment. Here, one of the output shafts14of the gearbox drives an integrated generator16via the driving device20. The turbomachine10also comprises the integrated generator16. The generator16allows to convert mechanical energy from the rotation of its input shaft18into electrical energy. The driving device20comprises a first electric motor30, and control means configured to control the first electric motor30. The first electric motor30may be a motor/generator. In other words, the first electric motor30may be configured to operate in a generator mode by supplying electrical energy and to operate in a motor mode by recovering electrical energy. In particular, the first electric motor30may be equipped with a battery. The driving device20comprises a second electric motor40, and control means configured to control the second electric motor40. The second electric motor40may be a motor/generator. The first and second electric motors30,40are arranged to transfer electrical power from one to the other. Preferably, the first and second electric motors30,40, are asynchronous in alternative current. The driving device20may comprise reversible power converters32,42arranged between the first and second electric motors30,40so as to reversibly transfer electrical power from one to the other. More specifically, the first electric motor30is connected to a first power converter32, and the second electric motor40is connected to a second power converter42, and the first and second power converters32,42are connected together. A power converter can be an inverter or a straightener. The driving device20also comprises an epicyclic reduction gear train50. The properties of the epicyclic reduction gear train are used to adapt the speed of rotation of the input shaft18of the generator16. FIGS.4a,4band4cshow an epicyclic reduction gear train50. The epicyclic reduction gear train50comprises a central planetary gear52A, arranged to be rotatable about the axis of the gearbox at a rotational speed, denoted ωA, and a planet carrier52U arranged to be rotatable about the axis of the gearbox at a rotational speed, denoted ωU. The epicyclic reduction gear train50also comprises planet gears52S which mesh with the central planetary gear52A and are carried by a planet carrier52U. The epicyclic reduction gear train50also comprises an external ring gear52B arranged to be rotatable about the axis of the gearbox at a rotational speed, denoted ωB, and with which the planet gears52S also mesh. In the epicyclic reduction gear train50, the three elements, namely the central planetary gear52A, the planet carrier52U and the ring gear52B, are rotatable about the axis of the gearbox. For example, the ring gear52B is free to rotate within a fixed casing52C that is configured to protect the gearbox50. The operation of the epicyclic reduction gear train50is governed by the Willis formula. This is a two-degree-of-freedom mechanism, in which the knowledge of the rotational speeds of two elements among the central planetary gear52A, the planet carrier52U and the ring gear52B, allows the calculation of the rotational speed of the third element. The Willis formula is expressed by the following equations: ωA-ωUωB-ωU=k[Math1]orωA-k×ωB+(k-1)×ωU=0[Math2] with ωA the rotational speed of the central planetary gear52A, ωU the rotational speed of the planet carrier52U, ωB the rotational speed of the ring gear52B, and the factor k, also referred to as ratio, a constant determined by the geometry of the gears. For the gearbox inFIG.4, the factor k follows the following equation: k=-ZBZA[Math3] where ZA is the number of teeth of the central planetary gear52A and ZB is the number of teeth of the ring gear52B. The factor k is therefore negative with a modulus less than 1. The output shaft14of the accessory gear box12is coupled to one of the three elements of the gearbox50, the input shaft18of the generator16is coupled to a second element of the gearbox50, and the first electric motor30is coupled to the third element of the gearbox50to control the rotational speed of the latter. According to the invention, the control means are configured to change the rotational speed of the third element, i.e. the rotational speed ω30of the first electric motor30, so that the second element, i.e. the generator16, is driven in rotation at a constant speed. In order to obtain a constant rotational speed of the input shaft18of the generator16for a given rotational speed of the output shaft14of the accessory gear box12, it is possible to vary the rotational speed of the third element of the gearbox50. Six kinematic combinations are possible for positioning the three pieces of equipment, namely the accessory gear box12, the generator16and the first electric motor30, relative to the three elements of the epicyclic reduction gear train50. The second electric motor40is also coupled to one of the elements of the gearbox50that is not coupled to the first electric motor30. The second electric motor40may be positioned on the axis of the generator16or on the axis of the accessory gear box. The first electric motor30and the second electric motor40each comprise a stator and a rotor. The first and second electric motors30,40are controllable in terms of the torque applied to their rotor and the rotational speed ω30, ω40of their rotor. The torque and the speed of each electric motor30,40are then controlled by the electrical power and the frequency of the current sent by the power converters32,42dedicated to each. Furthermore, the second electric motor40is electrically linked to the first electric motor30by means of the reversible power converters32,42to transfer power from one to the other. The position of the second electric motor40doubles the number of possible combinations for the driving device20. This results in twelve combinations listed in the table below. Table 1 also shows the function giving the rotational speed ω16of the generator16from the rotational speed ω12of the output shaft14of the accessory gear box12and the rotational speed ω30of the first electric motor30. The rotational speed ω40of the second electric motor40is determined by the rotational speed of the equipment with which it is coupled in series on the gearbox50, either the shaft of the generator16or the output shaft14of the accessory gear box12. In this table, the option1corresponds to cases where the second electric motor40is coupled in series with the generator16on the same element of the gearbox50, and the option2corresponds to cases where the second electric motor40is coupled in series with the output shaft of the accessory gear box12on the same element of the gearbox50. TABLE 1Connection secondConnection accessory gearelectric motorbox/generator/first electric motorGenerator speedOption 1Option 2Accessory gear box 12 connectedto the planet carrier 52UFirst electricGeneratormotor 30161ARing gearPlanetaryω16 = (1 − k) × ω12 + k × ω30PlanetaryPlanet52Bgear 52Agear 52Acarrier 52U1BPlanetary gear 52ARing gear 52Bω16=-ω12×1-kk+ω30kRing gear 52BPlannet carrier 52UAccessory gear box 12 connectedto the planet carrier 52BFirst electricGeneratormotor 30162APlanet carrierPlanetaryω16 = k × ω12 + (1 − k) × ω30PlanetaryRing gear52Ugear 52Agear 52A52B2BPlanetary gear 52APlanet carrier 52Uω16=-ω12×1-kk+ω301-kPlanet carrier 52URing gear 52BAccessory gear box 12 connectedto the planet carrier 52AFirst electricGeneratormotor 30163ARing gear 52BPlanet carrier 52Uω16=ω121-k-ω30×k1-kPlanet carrier 52UPlannet carrier 52A3BPlanet carrier 52URing gear 52Bω16=ω12k-ω30×1-kkRing gear 52BPlannet carrier 52A The torques delivered by the accessory gear box12, the generator16, and the first electric motor30are connected by a balance expression of the gear train. In particular, a study of the gearbox50allows to obtain the following train balance relationship and power balance relationship: CA+CB+CU=0 [Math 4] ωA×CA+ωB×CB+ωU×CU=0 [Math 5] where CA is the torque on the planetary gear52A, CB is the torque on the ring gear52B, CU is the torque on the planet carrier52U, ωA is the rotational speed of the central planetary gear52A, ωB is the rotational speed of the ring gear52B and ωU is the rotational speed of the planet carrier52U. This results in a torque at the level of the first electric motor30, and thus a driving or generating power at the level of this motor depending on the direction of the speed and the torque. The second electric motor40is connected in series with the generator16or with the accessory gear box12, and thereby the rotational speed ω40of the second electric motor40is determined to be equal to that of this equipment. Thus, the second electric motor40provides an additional degree of freedom to the driving device depending on the torque it exerts and which is added to that of the generator16or the accessory gear box12on the corresponding element of the gearbox50. This additional degree of freedom is used to provide a power transfer with the first electric motor30. Indeed, without the addition of the second electric motor40which allows the transfer of power with the first electric motor30, the power drawn off from the axis of the accessory gear box12would in certain phases of flight of the turbomachine be less than the electrical power delivered by the generator16and in certain phases of flight of the turbomachine greater than the requirements of the phase of flight. In the case of an electrical power delivered by the generator16being greater than the power drawn off from the accessory gear box12, the power gain comes from the electrical power drawn off by the first electric motor in motor mode. In the case of an electrical power delivered by the generator16is less than the power drawn off from the accessory gear box12, the power loss is drawn off by the first electric motor30in generator mode. In the absence of the second electric motor, the battery of the first electric motor30would allow to retrieve the electrical power during the generating phases and to restore this electrical power during the driving phases. The driving mode of the first electric motor30allows it to operate in all four quadrants, in terms of torque and speed. The overall energy drawn off from the accessory gear box12during the entire flight phase then corresponds to the electrical energy delivered by the generator16. The choice of parameters such as the ratio k of the epicyclic gear train of the gearbox50and the input rotation speed on the side of the accessory gear box12must be optimized to meet different constraints, motor speed constraints, maximum power constraints of the electric machines. Indeed, the driving device20depends on several parameters including: the ratio k of the epicyclic gear train of the gearbox50, the ratio of the rotational speed ω12at the output of the accessory gear box12with respect to the rotational speed of the engine axis of the turbomachine and the maximum value of the rotational speed ω16of the generator16. A choice among the twelve configurations must be made by optimizing these parameters to achieve in particular the following objectives:having a speed of the generator16higher than the speed of the accessory gear box12;reducing the torque of the first electric motor30for optimizing the motor size;having the speed of the first electric motor30as high as possible;having the speed of the second electric motor40as high as possible;optimizing the power transfers between the first electric motor30and the second electric motor40. Not all combinations in Table 1 will allow to achieve these objectives. A specific optimization study of each combination is therefore necessary to motivate a choice of implementation on a turbomachine. The combinations described below present various advantages to be considered for an integration in a turbomachine. FIG.1illustrates the “1B-Option1” configuration in which the accessory gear box12is connected to the planet carrier52U, the generator16is connected to the ring gear52B, and the first electric motor30is connected to the central planetary gear52A. In this configuration, the second electric motor40is connected to the ring gear52B. This configuration allows to meet the following constraints:rotational speed ω16of the generator16higher than the rotational speed ω12of the accessory gear box12, in particular due to the connection of the generator16to the ring gear52B;reduction of the torque of the first electric motor30to optimize the size of the motor, in particular by connecting the first electric motor30to the planetary gear52A;the highest possible rotational speed ω30of the first electric motor30, in particular by the connection of the first electric motor30to the planetary gear52A; androtational speed ω40of the second electric motor40as high as possible, in particular by the connection of the second electric motor40to the ring gear52B. In this configuration, the control of the second electric motor40is limited to a torque control loop, as its speed is constant, the second electric motor40and the generator16being connected to the same element of the gearbox50. FIG.2illustrates the “1B-Option2” configuration in which the accessory gear box12is connected to the planet carrier52U, the generator16is connected to the ring gear52B, and the first electric motor30is connected to the central planetary gear52A. In this configuration, the second electric motor40is connected to the planet carrier52U. This configuration allows to meet the following constraints:rotational speed ω16of the generator16higher than the rotational speed ω12of the accessory gear box;reducing the torque of the first electric motor30to optimize the size of the motor; androtational speed ω30of the first electric motor30as high as possible. In this configuration, the control of the second electric motor40comprises a torque and speed control loop, the second electric motor40and the accessory gear box12being connected to the same element of the gearbox50. The choice of positioning the second electric motor40on the axis of the generator16(configuration “1B-Option1”) or on the axis of the accessory gear box12(configuration “1B-Option2”) depends on the application, and mainly on the layout and the cluttering of the equipment, and on the maximum speed of the turbomachine10and the maximum speed of the generator16which is delimited by the maximum torque, and therefore by the maximum power. FIG.3illustrates the “2B-Option1” configuration in which the accessory gear box12is connected to the ring gear52B, the generator16is connected to the planet carrier52U, and the first electric motor30is connected to the central planetary gear52A. In this configuration, the second electric motor40is connected to the planet carrier52U. The choice of the configuration depends on the power levels of the considered application. The configurations1A and1B, independently of the Option, allow to meet the majority of the applications and the various major constraints. In the configuration1B, Option1or Option2, the lack of loss is due to the transfer of electrical power. Indeed, the first electric motor30may recover energy in generator mode through the epicyclic reduction gear train50and return it to the second electric motor40, or retrieve energy from the second electric motor40and return it in motor mode to the epicyclic reduction gear train50. In operation the epicyclic reduction gear train50behaves in three different ways. First, if the speed of the shaft14of the accessory gear box12is such that the speed of the generator16corresponds to the value of the constant speed, the control speed of the first electric motor30is zero and the speed of the generator16is related to the speed of the shaft14of the accessory gear box12by the reduction ratio of the epicyclic gear train at zero speed of the first electric motor30. Secondly, if the speed of the shaft14of the accessory gear box12is such that the speed of the generator16is greater than the value of the constant speed, the first electric motor30is driven to operate in a certain direction of rotation in the generator mode to reduce the speed of the generator16. The recovered energy is then returned to the second electric motor40operating in motor mode. Third, if the speed of the shaft14of the accessory gear box12is such that the speed of the generator16is less than the requirements of the turbomachine10, the first electric motor30is driven to operate in the other direction of rotation in motor mode to increase the speed of the generator16. The energy returned to the first electric motor30comes from the energy recovered from the second electric motor40operating in generator mode. The power drawn off from the accessory gear box12is converted entirely to the power delivered by the generator16. Depending on the design and the technology of the motors, preferably asynchronous, the redundancy of the motors to ensure high a reliability has only a small impact on the size of the motors. The invention also relates to a method for regulating the speed of an integrated generator16of a turbomachine10as previously described. The method comprises a step of changing the speed of the third of the three elements by driving the first electric motor30by means of the control means so that the second of said three elements, i.e. the generator16, is driven in rotation at a constant speed. In particular, the speed of the first electric motor30is adapted to the speed of the output shaft of the accessory gear box12so that the speed of the generator16is constant. | 18,073 |
11859559 | DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment will be described with reference to the drawings. FIG.1is a schematic diagram showing an aircraft engine1and an electric power generating apparatus13according to the embodiment. As shown inFIG.1, the aircraft engine1is a two-shaft gas turbine engine and includes a fan2, a compressor3, a combustor4, a turbine5, a high-pressure shaft6, and a low-pressure shaft7. The fan2is arranged at a front portion of the aircraft engine1and is surrounded by a fan casing. The turbine5includes a high-pressure turbine8at a front stage side and a low-pressure turbine9at a rear stage side. The high-pressure turbine8is coupled to the compressor3through the high-pressure shaft6. The high-pressure shaft6is a tubular shaft body including therein a hollow space. The low-pressure turbine9is coupled to the fan2through the low-pressure shaft7. The low-pressure shaft7is inserted into the hollow space of the high-pressure shaft6. A connecting shaft11extending outward in a radial direction is connected to the low-pressure shaft7such that the low-pressure shaft7can transmit power to the connecting shaft11. A gear box12is connected to the connecting shaft11such that the connecting shaft11can transmit the power to the gear box12. The electric power generating apparatus13is connected to the gear box12such that the gear box12can transmit the power to the electric power generating apparatus13. To be specific, rotational power of the low-pressure shaft7is transmitted through the connecting shaft11and the gear box12to the electric power generating apparatus13. Since rotational frequency fluctuation of the low-pressure shaft7is larger than rotational frequency fluctuation of the high-pressure shaft6, a rotational frequency fluctuation range of the power input to the electric power generating apparatus13becomes large. It should be noted that the power to be transmitted to the electric power generating apparatus13may be taken out from the high-pressure shaft6instead of the low-pressure shaft7. FIG.2is a block diagram showing the electric power generating apparatus13shown inFIG.1. As shown inFIG.2, the electric power generating apparatus13includes an emergency cut-off device20(disconnect assembly), a manual transmission21, a continuously variable transmission22, an electric power generator23, first to third rotational frequency sensors24to26, and an electric power generation controller27. The rotational power taken out from the low-pressure shaft7of the aircraft engine1is input to the electric power generator23through the emergency cut-off device20, the manual transmission21, and the continuously variable transmission22. The emergency cut-off device20is a power transmission mechanism to which the rotational power taken out from the aircraft engine1is input and which cuts off the power transmission at the time of the occurrence of an emergency. To be specific, the emergency cut-off device20is normally maintained in a power transmitting state, and in an emergency, the emergency cut-off device20can change from the power transmitting state to a power transmission cut-off state. The emergency cut-off device20may be a disconnect which is driven by an external command (for example, a command from a pilot) and cuts off the power transmission, a thermal disconnect which automatically cuts off the power transmission by utilizing the motion of a material by heat characteristic of the material when heat exceeds a predetermined upper limit, or a fuse disconnect which twists and breaks when the input rotational power becomes excessive. The emergency cut-off device20is arranged upstream of the manual transmission21. Therefore, when the emergency cut-off device20cuts off the power transmission at the time of the occurrence of the abnormality, the power transmission to all of the manual transmission21, the continuously variable transmission22, and the electric power generator23is cut off. Thus, the entire apparatus is appropriately protected at the time of the occurrence of the abnormality. The rotational power taken out from the aircraft engine1is input to the manual transmission21through the emergency cut-off device20. The manual transmission21is a transmission configured to select a gear train, by which the power is transmitted, from a plurality of gear trains and perform speed change. In the present embodiment, as one example, the manual transmission21is of a two-stage speed change type and includes a lower stage (equal speed stage) and an upper stage (speed increasing stage) having a larger change gear ratio (smaller reduction ratio) than the lower stage. When performing shift-up from the lower stage to the upper stage or performing shift-down from the upper stage to the lower stage, the manual transmission21changes from a state where one gear train is being selected to a state where another gear train is being selected through a disengaged state (neutral state). The rotational power which has been changed in speed by and output from the manual transmission21is input to the continuously variable transmission22. For example, a toroidal continuously variable transmission can be used as the continuously variable transmission22. The toroidal continuously variable transmission changes the change gear ratio in such a manner that a power roller sandwiched by input and output discs is tilted by changing the position of the power roller by an actuator. Since the toroidal continuously variable transmission is publicly known, the explanation of a detailed structure thereof is omitted. It should be noted that the continuously variable transmission may be of a different type, and for example, may be a hydraulic transmission (Hydro Static Transmission). The rotational power which has been changed in speed by and output from the continuously variable transmission22is input to the electric power generator23. The electric power generator23is an AC generator. For example, when the power having a constant rotational frequency is input to the electric power generator23, the electric power generator3generates alternating current having a constant frequency. The electric power generated by the electric power generator23is supplied to an electrical apparatus (not shown) mounted on the aircraft. The manual transmission21, the continuously variable transmission22, and the electric power generator23are integrated with each other as an IDG unit30. To be specific, the manual transmission21, the continuously variable transmission22, and the electric power generator23are accommodated in a housing31(FIG.3) as described below. It should be noted that the IDG unit30may accommodate the emergency cut-off device20in addition to the manual transmission21, the continuously variable transmission22, and the electric power generator23. The first rotational frequency sensor24detects an input rotational frequency N1of the manual transmission21. The second rotational frequency sensor25detects an output rotational frequency N2of the manual transmission21(i.e., an input rotational frequency of the continuously variable transmission22). The third rotational frequency sensor26detects an output rotational frequency N3of the continuously variable transmission22. The electric power generation controller27controls a speed change operation of the manual transmission21and a speed change operation of the continuously variable transmission22in accordance with the rotational frequencies N1, N2, and N3detected by the first to third rotational frequency sensors24to26. FIG.3is a sectional view showing the IDG unit30shown inFIG.2.FIG.4is a diagram when viewed from a direction indicated by an arrow IV shown inFIG.3. As shown inFIGS.3and4, the IDG unit30includes the housing31accommodating the manual transmission21, the continuously variable transmission22, and the electric power generator23. To be specific, since the manual transmission21is accommodated in the housing31accommodating the continuously variable transmission22and the electric power generator23, the apparatus is made compact, and handleability of the apparatus improves. The housing31includes a housing main body portion31aand an attaching portion31bat which an input opening31cis formed. The manual transmission21is connected to the continuously variable transmission22through a power transmission mechanism32(for example, a gear train). The continuously variable transmission22is connected to the electric power generator23through a power transmission mechanism33(for example, a gear train). A power transmission path (the continuously variable transmission22,23) between the manual transmission21and the electric power generator23is complete in the housing31. An axis X1of the manual transmission21, an axis X2of the continuously variable transmission22, and an axis X3of the electric power generator23are parallel to each other. It should be noted that the term “parallel” does not have to denote “completely parallel,” and slight misalignment is acceptable. For example, an angle between the axes may be in a range from 10° to −10°. Moreover, in the present embodiment, the axes X1to X3are simply parallel to each other. However, the axes X1to X3may be set such that: the axes X1to X3are skew lines; and when viewed from one direction, the axes X1to X3are parallel to each other. For example, the axes X1to X3may be set such that: when viewed from a direction perpendicular to the axis X1and an arrangement direction D in which the continuously variable transmission22and the electric power generator23are arranged (i.e., from a viewpoint ofFIG.3), the axes X1to X3are parallel to each other; and when viewed from the arrangement direction, at least two of the axes X1to X3intersect with each other. The continuously variable transmission22and the electric power generator23are provided adjacent to each other in a direction perpendicular to the axes X2and X3. The manual transmission21is arranged in an accommodating space S of the housing31so as to be located closer to the attaching portion31bthan the continuously variable transmission22and the electric power generator23. An input shaft41of the manual transmission21is inserted into the input opening31cof the attaching portion31band projects to an outside. When viewed from a direction along the axis X1, the manual transmission21is arranged so as to overlap the continuously variable transmission22and the electric power generator23. In the arrangement direction D in which the axis X2of the continuously variable transmission22and the axis X3of the electric power generator23are lined up, the axis X1of an output shaft42of the manual transmission21is located between the axis X2of the continuously variable transmission22and the axis X3of the electric power generator23. In the present embodiment, when viewed from the direction along the axis X1, the axis X1of the manual transmission21is sandwiched between the continuously variable transmission22and the electric power generator23. It should be noted that when viewed from the direction along the axis X1, the manual transmission21, the continuously variable transmission22, and the electric power generator23do not have to be lined up in a row. For example, as shown inFIG.5, the axes X1to X3may be set such that: the axis X1of the manual transmission21is located between the axis X2of the continuously variable transmission22and the axis X3of the electric power generator23in the arrangement direction D; and a line connecting the axis X1and the axis X2may form an angle θ with respect to the arrangement direction D, i.e., the angle θ between a line connecting the axis X2and the axis X3and the line connecting the axis X1and the axis X2is larger than 0° and smaller than 90°. In the present embodiment, the input shaft41and the output shaft42of the manual transmission21are coaxially arranged. The axis X1of the input and output shafts41and42of the manual transmission21is arranged between the continuously variable transmission22and the electric power generator23. According to this configuration, a power transmission path extending from the manual transmission21through the continuously variable transmission22to the electric power generator23is made compact. The attaching portion31bis smaller in diameter than the housing main body portion31a. The continuously variable transmission22and the electric power generator23are accommodated in the housing main body portion31a, and the manual transmission21is supported by the attaching portion31bby being fitted to an inner peripheral surface of the attaching portion31b. To be specific, since the attaching portion31bof the housing31can be utilized as a support structure for the manual transmission21, the support structure for the manual transmission21is simplified. Moreover, since an inner peripheral space of the attaching portion31bis utilized as an accommodating space accommodating the manual transmission21, the IDG unit30is made compact by effective utilization of the space. Furthermore, since the manual transmission21is provided at the inner peripheral surface of the attaching portion31bof the housing31, the attaching portion31bis relatively large in diameter, and attachment stability of the housing31improves. FIG.6is a sectional view showing the manual transmission21shown inFIG.3. As shown inFIG.6, the manual transmission21includes a planetary gear mechanism40, the input shaft41, the output shaft42, and a casing43. The planetary gear mechanism40includes a sun gear51, a ring gear52, a planetary gear53, a carrier54, a one-way clutch55, and a brake56. The input shaft41is connected to the carrier54holding the planetary gear53of the planetary gear mechanism40. The output shaft42is connected to the sun gear51of the planetary gear mechanism40. The brake56supported by the casing43is connected to the ring gear52. The input shaft41includes: a first shaft portion41aprojecting from the casing43toward an input side; and a second shaft portion41baccommodated in the casing43. The second shaft portion41bis connected to the carrier54. The second shaft portion41bis tubular and includes an internal space that is open toward the output shaft42. It should be noted that inFIG.6, the carrier54is formed integrally with the input shaft41, but the carrier54may be formed separately from the input shaft41and may be fixed to the input shaft41. The output shaft42includes a tip end portion42ainserted into the internal space of the tubular second shaft portion41b. The tip end portion42aof the output shaft42is supported by the second shaft portion41bof the input shaft41through a bearing (not shown) such that the output shaft42is rotatable. The sun gear51is connected to a portion of the output shaft42which portion is located at an output side of the tip end portion42a(i.e., located downstream of the tip end portion42a). The one-way clutch55is sandwiched between the input shaft41and the output shaft42. Specifically, the one-way clutch55is annular and is sandwiched between an inner peripheral surface of the second shaft portion41bof the input shaft41and an outer peripheral surface of the tip end portion42aof the output shaft42. The one-way clutch55transmits power only in one rotational direction and does not transmit the power in an opposite rotational direction. The one-way clutch55transmits rotational power from the input shaft41to the output shaft42but does not transmit the rotational power from the output shaft42to the input shaft41. For example, the one-way clutch55is of a known sprag type. The one-way clutch55is arranged at a radially inner side of the ring gear52. The ring gear52includes internal teeth which mesh with the planetary gear53. The brake56is connected to an outer peripheral surface of the ring gear52while being supported by the casing43. The brake56operates between an operating state in which the ring gear52is fixed to the casing43and a non-operating state in which the ring gear52is rotatable relative to the casing43. Specifically, the brake56includes a friction clutch61and a piston62configured to apply press-contact force to the friction clutch61. It should be noted that the brake56may include a component other than the friction clutch as long as the brake56can realize a state where the ring gear52is unrotatable relative to the casing43and a state where the ring gear52is rotatable relative to the casing43. The friction clutch61is interposed between an inner peripheral surface of the casing43and the outer peripheral surface of the ring gear52. The friction clutch61is, for example, a multiple disc clutch. Specifically, the friction clutch61includes a friction plate65and a mating plate66. The friction plate65is connected to the ring gear52so as to be unrotatable relative to the ring gear52and movable relative to the ring gear52in the direction along the axis X1. The mating plate66is connected to the casing43so as to be unrotatable relative to the casing43and movable relative to the casing43in the direction along the axis X1. The piston62is opposed to the friction clutch61. The piston62is supported by the casing43so as to be slidable. The casing43includes a hydraulic pressure passage43athrough which hydraulic pressure is applied to the piston62. Pressure oil is supplied to the hydraulic pressure passage43bby a hydraulic pump (not shown) driven by the power of the aircraft engine1. Since the pressure oil supplied from the hydraulic pressure passage43apushes the piston62, the piston62presses the friction clutch61, and the friction clutch61becomes an engaged state (the operating state of the brake56). When the hydraulic pressure applied from the hydraulic circuit43ato the piston62decreases, and the piston62retreats, the friction clutch61becomes a disengaged state (the non-operating state of the brake56). It should be noted that the actuator configured to press the friction clutch61is not limited to a hydraulic actuator, such as the piston62, and may be a different actuator (for example, an electromagnetic actuator). According to the above configuration, the manual transmission21can be formed in a thin shape that is compact in the direction along the axis X1. Therefore, an occupied space located upstream of the continuously variable transmission22in the IDG unit30is suppressed. Moreover, since the manual transmission21is of a thin type, the manual transmission21bis stably supported by the attaching portion31bwhile being accommodated in the inner peripheral space of the attaching portion31bof the IDG unit30. FIGS.7A and7Bare schematic diagrams for explaining an operation principle of the manual transmission21shown inFIG.6. As shown inFIG.7A, in the manual transmission21, when the brake56becomes the operating state, the ring gear52is fixed to the casing43, and the rotational power of the input shaft41is transmitted to the output shaft42through the carrier54, the planetary gear53, and the sun gear51. Thus, speed increase is performed (N1<N2). On the other hand, as shown inFIG.6B, in the manual transmission21, when the brake56becomes the non-operating state, the ring gear52is rotatable relative to the casing43, and the rotational power of the input shaft41is transmitted to the output shaft42through the one-way clutch55at equal speed (N1=N2). To be specific, when the brake56becomes the operating state, the manual transmission21becomes a high-speed stage (speed increase) that is the upper stage. When the brake56becomes the non-operating state, the manual transmission21is set to a low-speed stage (equal speed) that is the lower stage. However, the present embodiment is not limited to this as long as the upper stage is larger in a speed increasing ratio (smaller in the reduction ratio) than the lower stage. For example, the combination of two gear stages (the high-speed stage and the low-speed stage) of the manual transmission21does not have to be the combination of the speed increasing stage and the equal speed stage and may be, for example, the combination of the speed increasing stage and a speed decreasing stage or the combination of the equal speed stage and the speed decreasing stage. According to this configuration, when the brake56changes from the operating state to the non-operating state, the rotational frequency of the output shaft42connected to the load (electric power generator23) decreases as compared to the rotational frequency of the input shaft41. When the rotational frequency of the output shaft42becomes equal to the rotational frequency of the input shaft41, the one-way clutch55becomes an engaged state, and the rotational power of the input shaft41is transmitted to the output shaft42at equal speed. To be specific, two-stage speed change (equal speed and speed increase) can be realized by switching the operating state of the brake56. Then, since the two-stage manual transmission21is included in the electric power generating apparatus13, the apparatus can be made compact. REFERENCE SIGNS LIST 1aircraft engine13electric power generating apparatus20emergency cut-off device21manual transmission22continuously variable transmission23electric power generator27electric power generation controller30IDG unit31housing31battaching portion40planetary gear mechanism41input shaft42output shaft43casing51sun gear52ring gear53planetary gear54carrier55one-way clutch56brake61friction clutch62piston | 21,396 |
11859560 | DETAILED DESCRIPTION OF THE INVENTION FIG.1describes a turbomachine1which conventionally comprises a fan S or fan propeller and a gas generator comprising a low pressure compressor1a, a high pressure compressor1b, an annular combustion chamber1c, a high pressure turbine1d, a low pressure turbine1eand an exhaust nozzle1h. The high-pressure compressor1band the high-pressure turbine1dare connected by a high-pressure shaft2and together they form a high-pressure (HP) body. The low-pressure compressor1aand the low-pressure turbine1eare connected by a low-pressure shaft3and together they form a low-pressure (LP) body. The turbomachine1is here double-flow in the sense that two air flows, respectively primary F1and secondary F2, flow along the longitudinal axis X of the turbomachine. The air inlet flow F entering the turbomachine and passing through the fan S is divided in two downstream of the fan by an annular splitter nose17. A radially internal air flow flows within the splitter nose17and forms the primary flow F1which flows within the gas generator. A radially external air flow flows out of the splitter nose17and forms the secondary flow F2which flows around the gas generator. The fan S is driven by a fan shaft4which is driven by the LP shaft3by means of a reducer6. This reducer6is generally of the planetary or epicyclic type. The following description relates to a reducer of the epicyclic type, in which the planet carrier and the sun gear are rotatable, the ring gear of the reducer being stationary in the reference frame of the engine. The reducer6is positioned in the upstream portion of the turbomachine. A stationary structure comprising schematically, here, an upstream portion5aand a downstream portion5bwhich makes up the engine casing or stator5is arranged so as to form an enclosure E surrounding the reducer6. This enclosure E is here closed upstream by seals at the level of a bearing allowing the passage of the fan shaft4, and downstream by seals at the level of the passage of the LP shaft3. FIG.2shows an epicyclic reducer6. In the input, the reducer6is connected to the LP shaft3, for example by means of internal splines7a. Thus the LP shaft3drives a planetary sprocket referred to as the sun gear7. Classically, the sun gear7, whose axis of rotation is coincident with that of the longitudinal axis X, drives a series of sprockets referred to as planet gears8, which are equally spaced on the same diameter around the axis of rotation X. This diameter is equal to twice the operating centre distance between the sun gear7and the planet gears8. The number of planet gears8is generally defined between three and seven for this type of application. The assembly of planet gears8is held by a chassis referred to as planet carrier10. Each planet gear8rotates around its own axis Y, and meshes with the ring gear9. In the output we have:In this epicyclic configuration, the assembly of planet gears8drives the planet carrier10in rotation about the axis X of the turbomachine. The ring gear is secured to the engine casing or stator5via a ring gear carrier12and the planet carrier10is secured to the fan shaft4.In another planetary configuration, the assembly of the planet gears8is held by a planet carrier10which is attached to the engine casing or stator5. Each planet gear drives the ring gear which is fitted to the fan shaft4via a ring gear carrier12.In another differential configuration, the assembly of planet gears8is held by a planet carrier10which is connected to a first fan shaft5. Each planet gear drives the ring gear which is fitted to a second counter-rotating fan shaft4via a ring gear carrier12. Each planet gear8is mounted free in rotation by means of a bearing11, for example of the rolling bearing or hydrodynamic bearing type. Each bearing11is mounted on one of the axles10bof the planet carrier10and all axles are positioned relative to each other using one or more structural chassis10aof the planet carrier10. There are a number of axles10band bearings11equal to the number of planet gears. For reasons of operation, mounting, manufacture, inspection, repair or replacement, the axles10band the chassis10acan be separated into several parts. For the same reasons mentioned above, the toothing of a planet gear can be separated into several propellers or teeth each with a median plane P, P′. In our example, we detail the operation of a reducer in which each planet gear comprises two series of herringbone teeth cooperating with a ring gear separated into two half-ring gears:an upstream half-ring gear9aconsisting of a rim9aaand an attachment half-flange9ab. On the rim9aais the front propeller meshed with a propeller of the toothing8dof each planet gear8. The propeller of the toothing8dalso meshes with that of the sun gear7.a downstream half-ring gear9bconsisting of a rim9baand an attachment half-flange9bb. On the rim9bais the rear propeller meshed with a propeller of the toothing8dof each planet gear8. The propeller of the toothing8dalso meshes with that of the sun gear7. If the propeller widths vary between the sun gear7, the planet gears8and the ring gear9because of the toothing overlaps, they are all centred on a median plane P for the upstream teeth and on another median plane P′ for the downstream teeth. FIG.2thus illustrates the case of a single gearing stage reducer, i.e. a same toothing8dof each planet gear8cooperates with both the sun gear7and the ring gear9. Even though the toothing8dcomprises two series of teeth, these teeth have the same average diameter and form a single toothing referred to as herringbone. The attachment half-flange9abof the upstream half-ring gear9aand the attachment half-flange9bbof the downstream half ring gear9bform the attachment flange9cof the ring gear. The ring gear9is attached to a ring gear carrier by assembling the attachment flange9cof the ring gear and the attachment flange12aof the ring gear carrier by means of a bolted mounting, for example. The arrows inFIG.2describe the conveying of the oil in the reducer6. The oil enters the reducer6from the stator portion5into a dispenser13by different means which will not be specified in this view because they are specific to one or more types of architecture. The dispenser13comprises injectors13aand arms13b. The function of the injectors13ais to lubricate the toothings and the function of the arms13bis to lubricate the bearings. The oil is fed towards the injector13aand exits through the end13cto lubricate the toothings. The oil is also fed towards the arm13band flows through the feed opening13dof the bearing. The oil then circulates through the axle into one or more buffer areas10cand emerges through the orifices10din order to lubricate the bearings of the planet gears. FIG.3shows an aircraft turbomachine100with double-flow. The references used inFIG.1are used inFIG.3to designate the same elements. The air inlet flow F entering the turbomachine100and passing through the fan S, which is here a main fan, is split in two downstream of the fan S by an annular splitter nose17. A radially internal air flow flows into the splitter nose17and forms the primary flow F1. A radially external air flow flows out of the splitter nose17and forms the secondary flow F2which flows around the gas generator. The turbomachine1comprises a secondary fan S′ which comprises a propeller or bladed wheel located in the flow duct for the primary flow F1. The turbomachine100comprises a power transmission module110comprising a torque input110aconnected to the low pressure shaft3, a first torque output110bconnected to the main drive shaft104of the rotor and the propeller of the main fan S, and a second torque output110cconnected to the secondary drive shaft114of the rotor and the propeller of the secondary fan S′. FIG.4illustrates a double-flow turbomachine100in accordance with one embodiment of the invention. The power transmission module110of this turbomachine100comprises a reducer6similar to that ofFIGS.1and2, and comprises planet gears120with three independent toothings120a,120b,120c(only one planet gear being visible inFIG.4). The reducer6comprises the torque input110aand the two torque outputs110b,110c. The torque input110ais formed by the sun gear7of the reducer6, which is coupled to the low-pressure shaft3and is meshed with one of the toothings (120cin the example ofFIG.4) of each of the planet gears120. As will be explained in detail in the following, there are a multitude of possible configurations for the meshing of the toothings120a,120b,120cof the planet gears120.FIGS.4to8and9ato9jillustrate several possible configurations and several variants of a same configuration, among the multitude of possible configurations (over 1000). As can be seen inFIGS.4to8in particular, the diameters of the toothings120a,120b,120ccan be different. The toothings120a,120b,120cmay be arranged in any manner or according to their diameters, for example from smallest to largest diameter from upstream to downstream, or from largest to smallest diameter from upstream to downstream. Each of the toothings can be meshed with a ring gear or a sun gear. The advantage of changing the positional gears is that it allows to balance the forces in the planet gears120a,120b,120cand minimizes the residual moments. Generally speaking, the toothing located upstream is referred to as “upstream toothing”, the toothing located downstream is referred to as “downstream toothing” and the toothing located between the upstream and downstream toothings is referred to as the “intermediate toothing”. In the example shown inFIG.4, the larger diameter upstream toothing120ais meshed with a first ring gear12bforming the first torque output110band connected to the main shaft104. This main shaft104is rotatably guided by at least one rolling bearing170athat is carried by an upstream annular support170. The smaller diameter downstream toothing120cis meshed with the sun gear7which forms the torque input110aand is connected to the low-pressure shaft3. The intermediate toothing120bis meshed with a second ring gear12cwhich is stationary. The planet carrier10of the reducer6is rotatable and forms the second torque output110cby being connected to the secondary shaft114. This secondary shaft114is rotatably guided by at least one rolling bearing180athat is carried by a downstream annular support180. The transmission module110is located inside an annular casing160that comprises two coaxial annular walls160a,160bdefining the flow duct for the primary flow F1between them. The annular supports170,180are attached to the casing160. The bearings170a,180aare located respectively upstream and downstream of the module110. The ring gear12cis located between the supports170,180. The low-pressure shaft3is rotatably guided by at least one rolling bearing190awhich is carried by another annular support190. In the example shown inFIG.5, the smaller diameter upstream toothing120ais meshed with the sun gear7which forms the torque input110aand is connected to the low-pressure shaft3. An upstream end of the low-pressure shaft3or the sun gear7can be centred and guided inside the planet carrier10, upstream of the reducer6. The planet carrier10is rotatable and forms the second torque output110cby being connected to the secondary shaft114. The planet carrier10comprises a downstream tubular segment10ethrough which the low-pressure shaft3passes. The guide bearings (not shown) of the planet carrier10or of the secondary shaft114may be carried by the casing160, as discussed above. The downstream toothing120cof larger diameter is meshed with a stationary ring gear12cconnected to the casing160. The intermediate toothing120bis meshed with the ring gear12bwhich is rotatable and forms the first torque output110bby being connected to the main shaft104. The guide bearing (not shown) for this main shaft104may be carried by the casing160, as discussed above. FIG.6is a less schematic view of the reducer6inFIG.5. The types of toothings can be identical or different. For example, the toothings120a,120b,120ccan be all straight, helix or herringbone. Alternatively, all configurations and associations are possible. In the case ofFIG.7, for example, the upstream toothing120ais of the helix type, the intermediate toothing120bis of the straight type, and the downstream toothing120cis of the helix type. With a predefined propeller angle, it is possible with such a solution to cancel the axial forces on the planet gears120. In the case ofFIG.8, the upstream toothing120ais of the herringbone type, the intermediate toothing120bis of the straight type, and the downstream toothing120′cis of the helix type. Each of the planet gears120further comprises a fourth toothing120dmeshed with the sun gear7. The toothings120b,120′care located between the toothings120a,120dand the sun gear7comprises two independent and axially spaced toothings7afor meshing with the toothings120a,120d. This last solution is interesting because it allows to keep the direction of rotation on the two torque outputs110b,110c. In contrast to a solution with an output on a second sun gear, this solution is suitable for a reduction ratio higher than 1.9. In the configuration TR1ofFIG.9a, the smaller diameter downstream toothing120cis meshed with the sun gear7. The larger diameter upstream toothing is meshed with the ring gear12bwhich forms the first torque output110b, and the intermediate toothing120bis meshed with the ring gear12cwhich forms the second torque output110c. The planet carrier10is stationary. The configuration TR1′ inFIG.9bis close to the configuration TR1. The difference concerns the upstream toothing120awhich is meshed with the ring gear12cthat forms the second torque output110c, and the intermediate toothing120bis meshed with the ring gear12bthat forms the first torque output110b. In the configuration TR2ofFIG.9c, the smaller diameter downstream toothing120cis meshed with the sun gear7. The larger diameter upstream toothing120ais meshed with another sun gear7′ which forms the first torque output110b, and the intermediate toothing120bis meshed with the ring gear12cwhich forms the second torque output110cand which comprises a tubular segment12c1through which the sun gear7or the low-pressure shaft3passes. The planet carrier10is stationary. In the configuration TR2′ ofFIG.9d, the smaller diameter upstream toothing120ais meshed with the sun gear7. The larger diameter downstream toothing120cis meshed with another sun gear7′ which comprises a tubular segment7bthrough which the sun gear7or the low-pressure shaft3passes and which forms the second torque output110c. The intermediate toothing120bis meshed with the ring gear12bwhich forms the first torque output110b. The planet carrier10is stationary. In the configuration TR3ofFIG.9e, the intermediate toothing120bis meshed with the sun gear7. The larger diameter upstream toothing120ais meshed with another sun gear7′ which forms the first torque output110b. The smaller diameter downstream toothing120cis meshed with another sun gear7″ which comprises a tubular segment7bthrough which the sun gear7or the low-pressure shaft3passes and which forms the second torque output110c. The planet carrier10is stationary. The configuration TR3′ inFIG.9fis close to the configuration TR3. The difference concerns the upstream toothing120awhich is meshed with the sun gear7″ which forms the second torque output110c, and the downstream toothing120cis meshed with the sun gear7′ which forms the first torque output110b. In the configuration TR4ofFIG.9g, the smaller diameter downstream toothing120cis meshed with the sun gear7. The larger diameter upstream toothing120ais meshed with the ring gear12bwhich forms the first torque output110b. The intermediate toothing120bis meshed with the stationary ring gear12c. The planet carrier10is movable and comprises a tubular segment10ethrough which the sun gear7or the low-pressure shaft3passes and forms the second torque output110c. In the configuration TR4′ ofFIG.9h, the smaller diameter upstream toothing120ais meshed with the sun gear7. The larger diameter downstream toothing120cis meshed with the ring gear12cwhich forms the second torque output110c. The intermediate toothing120bis meshed with the stationary ring gear12b. The planet carrier10is movable and forms the first torque output110b. In the configuration TR5inFIG.9i, the smaller diameter downstream toothing120cis meshed with the sun gear7. The larger diameter upstream toothing120ais meshed with another sun gear7′ which forms the first torque output110b. The intermediate toothing120bis meshed with the stationary ring gear12b. The planet carrier10is movable and comprises a tubular segment10ethrough which the sun gear7or the low-pressure shaft3passes and forms the second torque output110c. In the configuration TR5′ ofFIG.9j, the intermediate toothing120bis meshed with the sun gear7. The larger diameter upstream toothing120ais meshed with the stationary ring gear12b. The smaller diameter downstream toothing120cis meshed with another sun gear7′ which comprises a tubular segment7bthrough which the sun gear7or the low-pressure shaft3passes and forms the second torque output110c. The planet carrier10is movable and forms the first torque output110b. FIG.10shows the directions of rotation of the parts of the reducer6of the power transmission module110. Only one planet gear120is shown and the arrow F3shows its direction of rotation around its axis Y. The sun gears7,7′ rotate in the same direction of rotation F4, F5around the longitudinal axis X of the reducer6. The ring gear12brotates in the opposite direction around this axis X. All these solutions allow to obtain two outputs from one input with constant reduction ratios. Depending on the desired reduction ratio and directions of rotation, one or more configurations can meet the need. For example, if a ratio of 1/1.5/8 is desired (i.e., a torque input110aat 1, a first torque output110bat 1:1.5 and a second torque output110cat 1:8) then one of the solutions to be preferred is of the type TR4. The power transmission module110according to the invention thus allows, from the high speed transmitted by the low-pressure shaft3, to provide two torque outputs with two different speeds, while minimizing the mass and overall dimension of the reducer6of this module. The invention is particularly suitable for low reduction ratios, e.g., less than two, and for powers in the megawatt range. Although the invention is illustrated in the scope of an aircraft double-flow turbomachine, the module can be equipped to any other type of turbomachine. | 18,693 |
11859561 | DETAILED DESCRIPTION FIGS.1A to1Cillustrate different aircraft engines10of a type preferably provided for use in subsonic flight. Each of the aircraft engines10is a gas turbine engine10. The gas turbine engines10generally comprises in serial flow communication an air inlet11, a compressor section12for pressurizing the air from the air inlet11, a combustor13in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, a turbine section14for extracting energy from the combustion gases, and an exhaust outlet15through which the combustion gases exit the gas turbine engine10. The gas turbine engine10have a longitudinal center axis17about which components rotate. In the gas turbine engines10shown inFIGS.1A and1C, the air inlet11is positioned forward of the compressor section12, whereas in the gas turbine engine10shown inFIG.1B, the air inlet11is positioned aft of the compressor section12. The gas turbine engine10ofFIG.1Aincludes a driven gear train16A mounted at a front end of the gas turbine engine10, and is an example of a “turboshaft” gas turbine engine10. The gas turbine engine10ofFIG.1Bincludes a propeller16B which provides thrust for flight and taxiing, and is an example of a “turboprop” gas turbine engine10. The gas turbine engine10ofFIG.1Cincludes a fan16C which rotates about a fan axis (inFIG.1C, collinear with the center axis17) and which provides thrust for flight, and is an example of a “turbofan” gas turbine engine10. The gas turbine engines10(sometimes referred to herein simply as “engines10”) have a central core18through which gases flow and which includes some of the turbomachinery of the engine10. The engine10ofFIG.1Bis a “reverse-flow” engine10because gases flow through the core18from the air inlet11at a rear portion, to the exhaust outlet15at a front portion. This is in contrast to “through-flow” gas turbine engines10, such as those shown inFIGS.1A and1C, in which gases flow through the core18of the engine10from a front portion to a rear portion. The direction of the flow of gases through the core18of the engine10ofFIG.1Bcan be better appreciated by considering that the gases flow through the core18in the same direction D as the one along which the engine10travels during flight for the engine. Stated differently, gases flow through the engine10ofFIG.1Bfrom a rear end towards a front end in the direction of the propeller16B. The direction of the flow of gases through the core18of the engines10ofFIGS.1A and1Ccan be better appreciated by considering that the gases flow through the core18in a direction D1that is opposite to the direction one along which the engines10travel during flight for the engines. Stated differently, gases flow through the engines10ofFIGS.1A and1Cfrom a front end towards a rear end in the direction of the exhaust outlet15. The engines10ofFIGS.1A to1Cmay have one or multiple spools which perform compression to pressurize the air received through the air inlet11, and which extract energy from the combustion gases before they exit the core18via the exhaust outlet15. The spools and this engine architecture are described in greater detail in U.S. patent application Ser. No. 15/266,321 filed on Sep. 15, 2016, the entire contents of which are hereby incorporated by reference. It will thus be appreciated that the expressions “forward” and “aft” used herein refer to the relative disposition of components of the engines10, in correspondence to the “forward” and “aft” directions of the engines10and aircraft including the engines10as defined with respect to the direction of travel. InFIGS.1A and1C, a component of the engines10that is “forward” of another component is arranged within the engine10such that it is located closer to the air inlet11. Similarly, a component of the engines10inFIGS.1A and1Cthat is “aft” of another component is arranged within the engines10such that it is further away from the air inlet11. InFIG.1B, a component of the engine10that is “forward” of another component is arranged within the engine10such that it is located closer to the propeller16B. Referring toFIGS.1A to1C, the air inlet11is the first point of entry for air into the core18of the engine10. The air inlet11has, or is defined by, an inlet duct21along which air flows as it drawn into the engine10. The inlet duct21may take different forms, as described in greater detail below. Referring toFIGS.1A and1B, the air inlet11is a radial air inlet11because, during operation of the engines10, air is drawn into the engine via the air inlet11along a substantially radial direction relative to the center axis17. The inlet duct21is defined by two annular walls22A,22B with sections that extend along substantially radial directions relative to the center axis17. Each wall22A,22B is shown as being an integral body. In an alternate embodiment, one or both of the walls22A,22B is made up of wall segments. Each annular wall22A,22B extends between a radially-outer portion23A and a radially-inner portion23B. The radially-inner portion23B is a portion of each wall22A,22B that is radially inward (i.e. closer to the center axis17of the engine10) than the radially-outer portion23A. Each wall22A,22B therefore extends from an outer surface or portion of the engine10radially inwards toward the core18. The walls22A,22B in the depicted embodiment also have portions extending in an axial direction relative to the center axis17. The radially-inner portions23B of each wall22A,22B have trailing ends24which, in the frame of reference of the engine10, are defined by both axial and radial direction vectors. An air opening or inlet25is defined at the radially-outer portions23A of the walls22A,22B. The inlet25is circumferential because it spans a portion or all of the circumference of the inlet duct21. The inlet25extends through an outermost surface26of the engine10. The outermost surface26may be defined by an engine covering, such as a nacelle or casing. The inlet25may be provided with a screen, filter, or mesh to prevent the ingress of foreign objects into the engine10. The inlet duct21extends from the inlet25in a radially-inward direction to an outlet24A of the inlet duct21which is defined by the radially-inner portions23B of each wall22A,22B. The outlet24A is within the engines10and forms part of their cores18. Referring toFIGS.1A and1B, the walls22A,22B are axially spaced apart from one another. InFIG.1A, the wall22B is aft of the wall22A in a direction along the center axis17. InFIG.1B, the wall22B is forward of the wall22A in a direction along the center axis17. The axial offset between the annular walls22A,22B defines an inner volume of the inlet duct21through which air is conveyed toward the compressor section12. The spaced-apart walls22A,22B therefore define an annular air passage27between them. The air passage27is an annular volume that extends radially inwardly at the radially-outer portions23A and which has both axial and radial direction vectors at the radially-inner portion23B of the walls22A,22B. Referring toFIG.1C, the air inlet11is an axial air inlet11because, during operation of the engine10, air is drawn into the engine via the air inlet11along a substantially axial direction relative to the center axis17. The inlet duct21is defined by an annular wall22A that extends along substantially an axial direction relative to the center axis17. The wall22A is shown as being an integral body. In an alternate embodiment, the wall22A is made up of wall segments. The annular wall22A extends between an axially-outer portion23A and an axially-inner portion23B. The axially-inner portion23B is a portion of the wall22A that is axially inward (i.e. closer to the compressor section12the engine10) than the axially-outer portion23A. The wall22A therefore extends from an outer surface or portion of the engine10axially inwards toward the core18. An inlet25is defined at the axially-outer portion23A of the wall22A. The inlet25is circumferential because it spans a portion or all of the circumference of the inlet duct21. The wall22A defines an annular air passage27. The air passage27is an annular volume that extends axially inwardly at the axially-outer portions23A. The inlet duct21extends from the inlet25in an axially-inward direction to an outlet24A of the inlet duct21which is defined by the axially-inner portion23B of the wall22A. The outlet24A is within the engine10and forms part of the core18. The air inlets11of the engines10ofFIGS.1A to1Cinclude structural supports, or struts30. The struts30may take different forms. Referring to the radial air inlets11ofFIGS.1A and1B, multiple air inlet struts30are located within the inlet duct21. Each strut30is part of the fixed structure of the engine10. Each strut30is a stationary component that helps to provide structure to the air inlet11. The struts30are circumferentially spaced-apart from one another about the center axis17within the inlet duct21. Each strut30extends across the inlet duct21between the annular walls22A,22B and through the annular air passage27. Each strut30is attached to the annular walls22A,22B. In the depicted embodiment, each strut30is integral with the walls22A,22B. In an alternate embodiment, one or more of the struts30can be removably mounted to the walls22A,22B. Each of the struts30in the depicted embodiment is a radial air inlet strut30because it extends radially inwardly. Stated differently, each strut30has a radial span defined between a radially-outer edge which defines the leading edge31A of the strut30near the radially-outer portions23A of the walls22A,22B, and a radially-inner edge which defines the trailing edge31B near the radially-inner portions23B of the walls22A,22B. Some or all of the trailing edge31B is radially closer to the center axis17than the leading edge31A. The position of the edges31A,31B of the strut30relative to the engine10may vary, and what remains constant is that the trailing edge31B is downstream of the leading edge31A relative to the flow of air over the strut30. Referring toFIGS.1A and1B, each strut30also has an axial span defined between the annular walls22A,22B of the inlet duct21. Referring toFIGS.1A and1B, one or more of the struts30is shaped like an airfoil. The airfoil shape of the strut30helps to guide the flow of air through the air inlet11. Each airfoil-shaped strut30includes the leading edge31A, and the trailing edge31B. The trailing edge31B is radially closer to the center axis17than the leading edge31A along some or all of its length. The strut30may be positioned radially inwardly of the inlet25and radially outwardly of the outlet24A. The strut30is positioned downstream of the inlet25and upstream of the outlet24A, relative to the direction of flow across the strut30from the leading edge31A to the trailing edge31B. In an embodiment, the strut30is positioned at or adjacent to the inlet25. The chord C of the strut30is therefore defined along a line extending between the leading and trailing edges31A,31B (seeFIG.2). The chord C therefore extends in a substantially radial direction. By “substantially radial”, it is understood that in the frame of reference of the engine10, the magnitude of the radial direction vector of the chord C may be much greater than the magnitude of the axial direction vector of the chord C. The chord C may have a camber or stagger angle. In alternate embodiments, one or more of the struts30do not have an airfoil shape. Referring toFIG.1A, the gas turbine engine10is instrumented to provide data for different components of the engine10. The engine10is equipped with sensors40, which may measure pressure, temperature, speed, angular velocity, torque, power, vibration, and the like. Non-limiting examples of possible sensors40for the engine10are now described in greater detail with reference to the gas turbine engine10ofFIG.1A, it being understood that the gas turbine engines ofFIGS.1B and1Cmay also be equipped with these sensors40, in addition to or separately from, different sensors40. Referring toFIG.1A, the engine10has a static pressure sensor40SP. The static pressure sensor40SP may take any configuration (e.g. a tap, a probe, etc.) which is capable of measuring or recording the static pressure of the air at the air inlet11, sometimes referred to herein as the “PS1” pressure, where the number “1” is used to designate the position of the air inlet11. The static pressure is the pressure applied by the air at the location of the static pressure sensor40SP when the air has substantially zero local velocity relative to the static pressure sensor40SP. In an embodiment, the static pressure sensor40SP excludes, prevents, or reduces the measurement of any dynamic pressure component of the air at the location of the static pressure sensor40SP, where the dynamic pressure is the pressure applied by the air as a result of its motion relative to the static pressure sensor40SP. In an embodiment, the static pressure sensor40SP contributes to the measurement of a total or ram pressure component of the air at the location of the static pressure sensor40SP, where the total pressure is the addition of static pressure and dynamic pressure at the static pressure sensor40SP. One possible configuration for the static pressure sensor40SP is now described with reference toFIG.2. The illustrated strut30has one or more internal strut passages33. Each strut passage33is a volume positioned within the body of the strut30that is sealed-off from the flow of air along the external surfaces of the strut30. The strut passage33allows for air to flow through the interior of the strut30in order to measure a static pressure at a location of the strut30, as explained in greater detail below. The strut passage33may be formed by drilling, etching, milling or any other operation for forming an internal volume within the material thickness of the strut30. Referring toFIG.2, the strut passage33extends to, through or is otherwise in fluid communication with, the static pressure sensor40SP. The fluid communication between the static pressure sensor40SP and the strut passage33allows the static pressure sensor40SP to obtain a pressure reading from the air within the strut passage33. The static pressure sensor40SP is fixedly mounted to the strut30or to any adjacent fixed structure using any suitable attachment technique. For example, and referring toFIG.2, the engine casing includes a boss36defining a groove for receiving the static pressure sensor40SP. The static pressure sensor40SP is attached to the engine inlet casing through the boss36, where the base of the groove of the boss36has an opening in fluid communication with the strut passage33. The boss36has an opening in fluid communication with the strut passage33. The internal strut passage33is thus in fluid communication with the static pressure sensor40SP when it is mounted to the strut30. Referring toFIG.2, the strut passage33extends from a root of the strut30towards a tip of the strut30. In an alternate embodiment, the strut passage33is defined by a fluid line which extends along an external surface of the strut30to the static pressure sensor40SP. In an alternate embodiment, the static pressure sensor40SP is remotely mounted away from the strut30and the engine casing. In such an alternate embodiment, a tube may extend from the boss36and be routed to a port of the static pressure sensor40SP. The strut30has additional components which allow for a pressure reading of the air at locations on the strut30to be generated. Referring toFIG.2, the strut30has multiple static pressure measurement taps38at the trailing edge31B of the strut30. The static pressure measurement taps38allow the static pressure sensor40SP to generate a reading of the static pressure at the static pressure measurement taps38(sometimes referred to herein simply as “taps38”) along the trailing edge31B. In an embodiment, and referring toFIG.2, the taps38are used to obtain a reading of only the static pressure at the location of the taps38on the trailing edge31B. The static pressure is the pressure applied by the air at the location of the taps38when the air has a substantially zero local velocity relative to the taps38. In an embodiment, the taps38exclude, prevent, or reduce the measurement of any dynamic pressure component of the air at the location of the taps38, where the dynamic pressure is the pressure applied by the air as a result of its motion relative to the taps38. The static pressure sensor40SP may be located elsewhere in the air inlet11, or may function to provide a measurement of the static pressure at different locations of the air inlet11. Referring toFIG.1A, another possible sensor40for the engine10is a compressor discharge pressure sensor40CD. The compressor discharge pressure sensor40CD may take any configuration (e.g. a tap, a probe, etc.) which is capable of measuring or recording the pressure of the air after it has been compressed and discharged by the compressor12, sometimes referred to herein as the “compressor discharge pressure” or the “P3” pressure, where the number “3” is used to designate the position of the compressor discharge pressure sensor40CD at the outlet of the compressor12. The compressor discharge pressure sensor40CD is disposed downstream of the compressor12. Referring toFIG.1A, another possible sensor40for the engine10is a shaft sensor40P. The shaft sensor40P may take any configuration (e.g. a probe, meter, optical, magnetic, etc.) which is capable of measuring or recording the power of an output shaft120of the engine10. The output shaft120is an elongated body that is rotatable about a shaft axis (inFIG.1A, the shaft axis is collinear with the center axis17). The output shaft120conveys power from the turbine18to a load driven by the engine10, which in the configuration of the engine10ofFIG.1A, is the driven gear train16A. The shaft sensor40P is capable of measuring or recording the power of the output shaft120, which sometimes referred to herein by the parameter “SHPN”. Referring toFIG.1C, another possible sensor40for the engine10is a speed sensor40N. The speed sensor40N may take any configuration (e.g. a probe, mechanical, optical, magnetic, etc.) which is capable of measuring or recording the rotational speed of the fan16C about the fan axis, sometimes referred to herein by the parameter “N1”, where the number “1” is used to designate the position of the speed sensor40N at the air inlet11. The aircraft engine10, or the aircraft to which the engine10is mounted, may have additional sensors40. For example, the aircraft may have a pitot tube to measure an airspeed of the aircraft or the dynamic pressure of the air at the location of the pitot tube. Another example of a sensor40of the engine10, and referring toFIG.1A, is a combustor discharge sensor40Q at a vane of the turbine section18. The combustor discharge sensor40Q may take any configuration (e.g. a tap, a probe, etc.) which is capable of measuring or recording the pressure of the hot combustion gases after they exit the combustor13, sometimes referred to herein by the parameter “Q4”, where the number “4” is used to designate the position of the combustor discharge sensor40Q at the outlet of the combustor13. The combustor discharge sensor40Q is disposed downstream of the combustor13. In an embodiment, the Q4parameter is not derived from the combustor discharge sensor40Q, and is instead a value stored in the memory of a computing system or controller of the engine10. In such an embodiment, the parameter Q4is a normalized value that characterizes a surface area of a turbine vane downstream of the outlet of the combustor13. This value is coded into the computing system or controller and does not vary over different engine operating cycles or conditions. In an embodiment, the value for the parameter Q4is constant for a given engine10, or a specific serial number of the engine10. Another example of a sensor40of the engine10, and referring toFIG.1A, is a bleed air sensor40B located where air is bled out of the compressor12. Air may be bled from the cold section of the engine10(i.e. the compressor12) for different purposes. One possible purpose is to bleed air to pressurize the cabin of the aircraft to which the engine10is mounted, and this may sometimes be referred to herein by the parameter “ECS”. Another possible purpose is to bleed air to maintain proper operating conditions for the engine10, such as to prevent surge in the compressor12or to reduce the effects of compressor surge, and this may sometimes be referred to herein by the parameter “HBOV”. The bleed air sensor40B may take any configuration (e.g. a tap, a probe, etc.) which is capable of measuring or recording a unit value or a normalized value for the parameters ECS and HBOV. In an embodiment, the bleed air sensor40B is a device which functions to output a signal indicating whether a bleed valve is actuated to a fully open position, a fully closed position, or is modulating at a position between fully opened and fully closed. The computing system or controller of the engine10may be able to determine from this output the bleed air parameter to use. In such a configuration, the bleed air sensor40B may be a component or feature of the bleed valve. Another example of a sensor40of the engine10, and referring toFIG.1A, is a temperature sensor40T located at the air inlet11. The temperature sensor40T may take any configuration (e.g. a tap, a probe, etc.) which is capable of measuring or recording the temperature of the air at the air inlet11, sometimes referred to herein by the parameter “T”, where the number “1” is used to designate the position of the temperature sensor40T at the air inlet11. In an embodiment, and referring toFIG.1A, the sensors40convert their readings or measurements into electrical signals that are provided to a controller or control system of the engine10. For example, the engine10ofFIG.1Ais used in an aircraft, and the control system for the engine10is a full-authority digital engine control (FADEC)420. The sensors40are communicatively coupled to the FADEC420for providing information to the FADEC420. In an embodiment, the FADEC420commands one or more of the sensors40to provide their measurements or recordings to the FADEC420. The FADEC420may also be coupled to the engine10for extracting other information from the engine10itself, and for controlling operation of the engine10. Referring toFIG.3, a system for determining the inlet total pressure400at the air inlet11is disclosed (sometimes referred to herein simply as the “system400”). The system400is composed of, or includes, the FADEC420and one or more of the sensor(s)40. An operator interface405may be coupled to the FADEC420, for example to receive inputs from an operator of the engine10, and for presenting information outputted by the FADEC420to the operator of the engine10. The FADEC420functions to implement the system400so as to determine the inlet total pressure P1of the air at the air inlet11of the engine, as described in greater detail below. The inlet total pressure P1is a total or ram pressure of the air at the air inlet11, where the inlet total pressure P1is the combination of the static pressure PS1and the dynamic pressure at the air inlet11. The inlet total pressure P1determined by the system400may be used for many different purposes of the engine10. For example, the inlet total pressure P1may be used by the FADEC420to determine the real pressure ratio across a given stage of the compressor12, and the overall pressure ratio across all of the stages of the compressor12. The inlet total pressure P1is provided to the FADEC420, and may be used by the FADEC420to determine different thermodynamic or aerodynamic properties of the engine10. In an embodiment, the system400determines the inlet total pressure P1from one or more other measured properties of the engine10. The system400in an embodiment does not obtain or measure the inlet total pressure P1directly, and may thus avoid one or more problems associated with trying to measure the inlet total pressure P1directly. For example, one technique for measuring the inlet total pressure P1directly involves using a P1sensor. Such sensors are often complex, add additional weight to the engine and are subjected to icing which may impact engine reliability. By not relying on such a sensor to obtain the inlet total pressure P1, the system400may avoid one or more problems associated with such a sensor and may further reduce the weight of the engine10. The FADEC420includes a mass flow module410which functions to provide other components of the FADEC420with a value for a mass flow W1C at the air inlet11. The mass flow W1C calculated or outputted by the mass flow module410is a corrected mass flow W1C. The corrected mass flow W1C is a mass flow rate that would pass through the air inlet11if the inlet pressure and temperature corresponded to ambient conditions at Sea Level, on a Standard Day (e.g. 101.325 kPa, 288.15 K). The mass flow W1C may be provided by the mass flow module410as an output in units of mass per unit of time. One or more inputs from the engine10and/or from the FADEC420are provided to the mass flow module410in order to determine the mass flow W1C. Referring toFIG.3, one such input is a first inlet total pressure P1IN. In an embodiment, such as when the FADEC420is powered up, the first inlet total pressure P1IN is an initial estimate or initial guess of the value of the inlet total pressure P1and is thus sometimes referred to herein as the “initial inlet total pressure P1IN”. As explained in greater detail below, the first inlet total pressure P1IN will be replaced or substituted with a revised inlet total pressure P1R after the FADEC420has performed one or more iterations to achieve the inlet total pressure P1. Therefore, the first inlet total pressure P1IN may be equal to, or the same as, the revised inlet total pressure P1R, after the system400has completed at least one iteration. The first inlet total pressure P1IN is thus the first value of the inlet total pressure that is provided to or by the system400before it functions to generate the inlet total pressure P1. The first inlet total pressure PIN may be a valued stored in memory and which is provided to the FADEC420when it is first started. In the embodiment where the FADEC420is starting up and has not yet generated a revised inlet total pressure P1R, the first inlet total pressure P1IN is an initial, first value for the inlet total pressure P1which may be stored in the FADEC420, or which may set or selected from a range of values. The range may be defined between a minimum initial inlet total pressure and a maximum initial inlet total pressure. In the embodiment where the FADEC420is starting up and has not yet generated a revised inlet total pressure P1R, the FADEC420may provide to the mass flow module410a value for the initial inlet total pressure P1IN that is one of a finite number (e.g. two) values. In an embodiment, the value for the initial inlet total pressure P1IN that the FADEC420provides to the mass flow module410is always the same when the FADEC420is first started. Therefore, the system400begins with a guess of what the inlet total pressure P1is or will be, and this guess is refined and modified in one or more subsequent iterations. During some operating conditions of the engine10, such as prior to engine startup and after shutdown when the FADEC420is on but the engine10is not drawing air into the air inlet11, the first inlet total pressure P1IN may be the primary parameter inputted into the mass flow module410to determine the mass flow W1C. During the same or different operating conditions of the engine10, such as during engine startup or flight, one or more other inputs are provided to the mass flow module410, in addition to the first inlet total pressure P1IN. Referring toFIG.3, the discharge pressure P3of the air discharged from the compressor12, which is measured with the compressor discharge pressure sensor40CD, is provided to the mass flow module410. The discharge pressure P3is used to define the overall pressure ratio across the compressor12, which is defined as the discharge pressure P3or the first inlet total pressure P1IN (or the revised inlet total pressure P1R). The overall pressure ratio is used to estimate the corrected mass flow W1C at the air inlet11. The mass flow W1C provided by the mass flow module410is primarily a function of the overall pressure ratio. However, other parameters/inputs may be provided to the mass flow module410in order to further improve the accuracy of the mass flow W1C and/or of the inlet total pressure P1obtained by the system400. Referring toFIG.3, one example of another such input to the mass flow module410is an altitude factor, shown inFIG.3as “Delta”. Delta is an altitude factor of the aircraft carrying the engine10. Delta is a normalised parameter that is a function of the atmospheric pressure at the altitude divided by atmospheric pressure at sea level. The atmospheric pressure may be provided by the pitot tube. Another example of an additional input to the mass flow module410is the correction factor Q4. The correction factor Q4is provided by the combustor discharge sensor40Q, or is stored at the FADEC420. The correction factor Q4can be used to correct the mass flow W1C based on engine conditions at the outlet of the combustor13. Another example of an additional input to the mass flow module410is the unit value or normalized value for the parameters ECS and HBOV provided by the bleed air sensor40B (which may be part of the bleed valve). The parameter ECS may have a small impact on the accuracy of value of the revised inlet total pressure P1R that is obtained by the system400, but may have a larger impact (e.g. approximately 5%) on the accuracy of the value for mass flow W1C that is provided by the mass flow module410. Of the inputs into the mass flow module410, the overall pressure ratio may have the greatest impact on the accuracy of the revised inlet total pressure P1R that is obtained by the system400, and the other inputs into the mass flow module410described above may improve the determination or accuracy of the mass flow W1C. One or more of the inputs Delta, Q4, ECS and HBOV may be stored in the FADEC420. In an embodiment, and referring toFIG.3, the mass flow W1C is calculated using another component or functionality of the FADEC420. The FADEC includes an auxiliary mass flow module410A which functions to provide a value for the mass flow W1C at the air inlet11based on inputs other than the overall pressure ratio. Referring toFIG.3, one such input is the power SHPN of the output shaft120provided by the shaft sensor40P. The mass flow W1C calculated or outputted by the auxiliary mass flow module410A and based on the power SHPN is the corrected mass flow W1C. The auxiliary mass flow module410A may have other inputs, such as those above, or different inputs. For example, and referring toFIG.3, one of the inputs into the auxiliary mass flow module410A is the temperature T1of the air at the air inlet11, which is provided by the temperature sensor40T. The temperature T1provided to the auxiliary mass flow module410A may represent a temperature value in units of degrees, or may be a normalized value (sometimes referred to as “Theta”) which is the temperature at the air inlet11divided by the temperature at International Standard Atmosphere (ISA) conditions for sea level. In an embodiment of the engine10, the temperature sensor40T is located in close proximity to, or may be incorporated into, the static pressure sensor40SP. In an embodiment of the engine10, the temperature sensor40T is located in close proximity to the taps38. The auxiliary mass flow module410A thus provides another technique for determining W1C based primarily on the normalized power SHPN of the output shaft1200, where the other inputs into the auxiliary mass flow module410A described above may improve the determination or accuracy of the mass flow W1C. In the embodiment where the input into the auxiliary mass flow module410A is the power SHPN, the auxiliary mass flow module410A is used to determine the mass flow W1C for a turboprop engine10such as the one shown inFIG.1B, or for a turboshaft engine10such as the one shown inFIG.1A. For example, the auxiliary mass flow module410A will use the power SHPN as the primary input when the aircraft engine10is a turboprop or turboshaft engine10. In an embodiment, and referring toFIG.3, the auxiliary mass flow module410A may also function to provide a value for the mass flow W1C at the air inlet11based on another input. This input is the rotational speed N1of the fan16C, which is measured by the speed sensor40N and provided to the FADEC420by the speed sensor40N. The rotation speed N1may be provided by the speed sensor40N, or manipulated by the FADEC420, to be employed in the auxiliary mass flow module410A as a corrected fan speed N1C. The auxiliary mass flow module410A thus provides another technique for determining W1C based primarily on the rotational speed N1of the fan16C, where the other inputs into the auxiliary mass flow module410A described above may improve the determination or accuracy of the mass flow W1C. In the embodiment where the input into the auxiliary mass flow module410A is the rotational speed N1, the auxiliary mass flow module410A is used to determine the mass flow W1C for a turbofan engine10, such as the one shown inFIG.1C. For example, the auxiliary mass flow module410A will use the rotational speed N1as the primary input when the aircraft engine10is a turbofan engine10. In an embodiment, and referring toFIG.3, the mass flow module410and the auxiliary mass flow module410A operate simultaneously and separately to generate separate and different values for the mass flow W1C, but only the mass flow W1C output from one of the mass flow module410and the auxiliary mass flow module410A is provided to be used by the system400to determine the inlet total pressure P1. The mass flow W1C output from the mass flow module410may be more accurate (i.e. more representative of actual mass flow at the air inlet11) than the mass flow W1C output from the auxiliary mass flow module410A. However, the system400still determines the mass flow W1C in the auxiliary mass flow module410A (as a function of the power SHPN or the speed N1) in parallel to the mass flow module410, in case the mass flow module410is unable to provide the mass flow W1C. This may occur if the compressor discharge pressure sensor40CD malfunctions or becomes inoperative, for example, such that it cannot provide the discharge pressure P3to the mass flow module410. In such an eventuality, the system400has a built-in redundancy and back-up in the auxiliary mass flow module410A, which will continue to output the mass flow W1C based on an input of the shaft power SHPN from the shaft sensor40P (for turboprop or turboshaft engines10) or based on an input of the rotational speed N1from the speed sensor40N (for turbofan engines10). When the mass flow module410and the auxiliary mass flow module410A operate simultaneously and separately to generate the mass flow W1C, the mass flow W1C from the auxiliary mass flow module410A is the mass flow W1C used by the system400to determine the inlet total pressure P1in the event that the mass flow W1C from the mass flow module410cannot be provided. An example of this logic is shown inFIG.3. The FADEC420has a gate412. The gate412receives the mass flow W1C from both the mass flow module410and the auxiliary mass flow module410A. The gate412includes a switch412A. The switch412A is responsive to a fault condition associated with the mass flow module410. For example, if the compressor discharge pressure sensor40CD is functioning normally and providing the discharge pressure P3to the mass flow module410(which may be a default condition), there is no fault condition and the switch412A will allow the mass flow W1C from the mass flow module410to be used by the system400. Alternatively, if the compressor discharge pressure sensor40CD is malfunctioning and/or incapable of providing the discharge pressure P3to the mass flow module410, there is a fault condition and the switch412A will move to allow the mass flow W1C from the auxiliary mass flow module410A to be used by the system400. The system400thus provides for estimating, calculating, and/or computing the mass flow W1C of the air at the air inlet11using the first inlet total pressure P1IN, the measured compressor discharge pressure P3, and possibly other measured parameters including, but not limited to, the shaft power SHPN and the fan rotational speed N1. While the mass flow W1C is an intermediary property used by the system400to determine the inlet total pressure P1, as explained in greater detail below, it may also be a valuable property on its own when performing different calculations and assessments of engine10performance and operation. For this reason, and as shown inFIG.3, each of the mass flow module410and the auxiliary mass flow module410A may output their mass flows W1C to other portions of the FADEC420or engine10. The system400therefore allows for the mass flow W1C at the air inlet11to be used by the FADEC420or the engine10for other purposes not related to pressure determination. In an alternate embodiment, the mass flow W1C is provided by only the mass flow module410using the overall pressure ratio as described above. In an alternate embodiment, the mass flow W1C is provided by only the auxiliary mass flow module410A using the shaft power SHPN as described above. In an alternate embodiment, the mass flow W1C is provided by only the auxiliary mass flow module410A using the fan rotational speed N1as described above. After the system400has determined the mass flow W1C, the mass flow W1C is used to determine the Mach number of the air at the air inlet11. Referring toFIG.3, the FADEC420includes a Mach number module430which functions to provide other components of the FADEC420with a value for the Mach number at the air inlet11. The mass flow W1C is the primary input to the Mach number module430. Using the mass flow W1C, and optionally other inputs, the Mach number module430outputs a calculated, estimated, or computed Mach number for the system400to use in determining the inlet total pressure P1. The Mach number module430may function to generate the Mach number using computational fluid dynamics (CFD) tables or curves which relate various values for the corrected mass flow W1C at the air inlet11to various values for the Mach number. Thus, the Mach number module430may perform CFD, or rely on existing CFD analysis, to establish a correlation between corrected mass flow W1C and the Mach number at the air inlet11. In an embodiment, and referring toFIG.3, the Mach number of the air at the air inlet11is determined using other inputs for the Mach number module430, in addition to the primary input of mass flow W1C. One example of such an input is the speed of the aircraft having the aircraft engine10, shown inFIG.3by the parameter “VTAS”. The aircraft speed VTAS may be provided by the pitot tube of the aircraft. The aircraft speed VTAS may be provided to the Mach number module430as a “true” airspeed, which is the speed of the aircraft relative to the air mass through which the aircraft is flying. In an embodiment, the aircraft speed VTAS is not a separate input, but is instead incorporated into the CFD tables or curves which relate various values for the corrected mass flow W1C at the air inlet11to various values for the Mach number. Another example of an additional input to the Mach number module430is the configuration of the aircraft having the aircraft engine10, shown inFIG.3by the parameter “AC”. The configuration AC may be a numerical value representative of a characteristic or feature of the aircraft and/or the engine10. For example, the configuration AC may be a numerical value representative of the engine10being used in a helicopter or an airplane, since these configurations may influence the Mach number at the air inlet11. For example, the configuration AC may be a numerical value representative of the engine10being mounted on the left or on the right of the aircraft, since these configurations of the engine10may influence the Mach number at the air inlet11. In an embodiment, the value for the configuration AC is stored in the memory of the FADEC420and is not an input provided from outside of the FADEC420. After the system400has determined the Mach number, the Mach number is used to determine a pressure ratio of the air at the air inlet11. The pressure ratio is defined as the revised inlet total pressure P1R at the air inlet11over an estimate of the static pressure PS1E of the air at the air inlet11. Referring toFIG.3, the FADEC420includes, embodies and/or uses one or more curve(s)440which plot the pressure ratio as a function of the Mach number, according to the following equation: P1RPS1E=f(Mach) Using the Mach number from the Mach number module430, the curve(s)440are able to compute or calculate the pressure ratio P1R/PS1E using, for example, a one-dimensional isentropic compressible flow function or equivalent. The system400may then use the pressure ratio P1R/PS1E in determining the inlet total pressure P1. The curve(s)440may assume certain properties, such as gamma being 1.4, where gamma is a property of the air at the cold section of the engine10. In a conventional application where the Mach number is already known, the pressure ratio can be computed from the known Mach number using the one-dimensional isentropic compressible flow function. However, since the Mach number is not known by the system400before it is estimated in the Mach number module430, it is required to first estimate the Mach number from the corrected mass flow W1C. However, the prediction of corrected mass flow W1C itself requires knowing in advance the value for the inlet total pressure P1such as by measuring it directly (which may have disadvantages explained above), but this is the variable that the system400is trying to determine in the first place because the system400does not directly measure the inlet total pressure P1in an embodiment. The system400thus performs one or more iterations to overcome this difficulty, as explained in greater detail below. Referring toFIG.3, the FADEC420includes a static pressure module450. The static pressure module450functions to provide other components of the FADEC420with a value for the real static pressure PSR at the air inlet11. The measured static pressure PS1obtained from the static pressure sensor40SP is the primary input into the static pressure module450. The static pressure module450outputs a calculated, estimated, or computed real static pressure PSR for the system400to use in determining the inlet total pressure P1. The static pressure module450may function to generate the real static pressure PSR using CFD tables or curves which relate various values for the measured static pressure PS1at the air inlet11to various values for the actual or real static pressure PSR. Thus, the static pressure module450may perform CFD, or rely on existing CFD analysis, to establish a correlation between measured static pressure PS1and the real static pressure PSR at the air inlet11. For example, in some instances, it may be necessary to correct a probe measurement of the static pressure PS1, using a process called “measure to real” compensation, to get the real value for the static pressure PSR. In an alternate embodiment, the static pressure module450does not receive an input of the measured static pressure PS1from the static pressure sensor40SP, and instead outputs the real static pressure PSR that has been approximated from other variables (measured or approximated), such as an altitude of the engine10. The real static pressure PSR from the static pressure module450is combined in the FADEC420with the pressure ratio P1R/PS1E to obtain the revised inlet total pressure P1R. Referring toFIG.3, the FADEC420has a multiplier460. The inputs to the multiplier460are the pressure ratio P1R/PS1E from the curve(s)440and the real static pressure PSR from the static pressure module450. In an alternate embodiment, one of the inputs into the multiplier460is the measured static pressure PS1instead of the real static pressure PSR. The revised inlet total pressure P1R is a modified or updated version of the first inlet total pressure P1IN, in that the revised inlet total pressure P1R is the result of the manipulations and calculations performed on the first inlet total pressure P1IN by the features of the system400and the inputs provided thereto. After a first iteration of the system400, it is possible that the revised inlet total pressure P1R is representative of the actual inlet total pressure P1of the air at the air inlet11. In another embodiment, after a first iteration of the system400, it is possible that the revised inlet total pressure P1R is not representative of the actual inlet total pressure P1of the air at the air inlet11. The system400therefore allows for the revised inlet total pressure P1R determined after a first iteration of the system400to be plugged back into the system400to run another iteration and obtain another revised inlet total pressure P1R that is more representative of the actual inlet total pressure P1. Referring toFIG.3, the revised inlet total pressure P1R is sent back to one or both of the mass flow module410and the auxiliary mass flow module410A. The revised inlet total pressure P1R is provided as an input to substitute or replace the first inlet total pressure P1IN, and one or both of the mass flow module410and the auxiliary mass flow module410A are operated to provide a new and revised mass flow W1C. By “substitute” or “replace”, it is understood as being any one of: using the revised inlet total pressure P1R instead of the first inlet total pressure P1IN, assigning the value of the revised inlet total pressure P1R to the first inlet total pressure P1IN and rerunning the sequence with the first inlet total pressure P1IN having the updated value, and any other combination that has the effect of rerunning the sequence with the newly obtained value. Referring toFIG.3, the FADEC420may have a delay module470. The delay module470stores in memory the revised inlet total pressure P1R received from the multiplier460. The delay module470transmits the revised inlet total pressure P1R to both of the mass flow module410and the auxiliary mass flow module410A. The delay module470may transmit the revised inlet total pressure P1R after a time delay, so as to permit the flow conditions of air at the air inlet11to change or settle before the system400performs another iteration. The delay module470may establish a cycle or scan duration, during which the system400must output the revised inlet total pressure P1R to the delay module470. The delay module470may then provide the revised inlet total pressure P1R to both of the mass flow module410and the auxiliary mass flow module410A at the end of the cycle or scan duration. The time delay or scan duration may be any unit of time. One possible and non-limiting example of a time delay or scan duration for the delay module470is 24 ms, such that the FADEC420runs an iteration of the system400every 24 ms. Once the revised inlet total pressure P1R is received at the mass flow module410and the auxiliary mass flow module410A, the system400is run again with the revised inlet total pressure P1R (and with subsequent values of the revised inlet total pressure P1R). The system400thus allows for indirectly determining the actual inlet total pressure P1at the air inlet11from one or more other measured parameters. In particular, the system400allows for indirectly determining the actual inlet total pressure P1at the air inlet11using the static pressure PS1as the only input of pressure of the air at the air inlet11. The system400also allows for indirectly determining the actual inlet total pressure P1at the air inlet11using input from other sensors40that are often already available on engines10and that are not subjected to icing, therefore increasing the reliability of the inlet total pressure P1without adding additional sensors and thus weight to the engine10. These other sensors40which are already available include, but are not limited to, the compressor discharge pressure sensor40CD, the power sensor40P, the temperature sensor40T, and the bleed air sensor40B. The system400thus allows for accurately determining the inlet total pressure P1without having to directly measure it. In an alternate embodiment, the inlet total pressure P1may be directly measured with a sensor to validate the inlet total pressure P1determined by the system400, or as a redundancy to the inlet total pressure P1determined by the system400. The system400may or may not have a convergence criteria to determine when/if the revised inlet total pressure P1R converges to a converged inlet total pressure P1C. The converged inlet total pressure P1C is a final value that is achieved after one or more iterations, and is, or corresponds to, the actual inlet total pressure P1. In an example of the system400iterating with a convergence criteria, the system400may repeat or iterate with different values for the revised inlet total pressure P1R until the values of the revised inlet total pressure P1R determined by the system400are numerically stable. Stated differently, the values of the revised inlet total pressure P1R determined by the system400over multiple cycles/iterations are substantially the same (i.e. within a given threshold/tolerance). This may be an indication that subsequent iterations of the system400will not provide changes to the determined revised inlet total pressure P1R, which may indicate that the revised inlet total pressure P1R has converged to the converged inlet total pressure P1C. In another example of the system400iterating with a convergence criteria, the system400may repeat or iterate with different values for the revised inlet total pressure P1R until the “output” equals the “input”. Stated differently, the system400continues to iterate until the revised inlet total pressure P1R that is substituted into the mass flow module410and auxiliary mass flow module410A is equal or substantially similar to the revised inlet total pressure P1R obtained at the multiplier460. Alternatively, the system400may iterate without requiring convergence. In an example of the system400iterating without a convergence criteria, the system may repeat or iterate with different values for the revised inlet total pressure P1R for a fixed or predetermined number of additional cycles. In an embodiment, the number of cycles is one additional cycle, such that the system400iterates with the revised inlet total pressure P1R a single additional instance. In at least some applications and engines with which the claimed method100and system400are used, a single additional sequence provides a reliable value and carries additional benefits of: a) reduced load at the controller and reduced energy consumption, due to requiring fewer operations than at least some prior art iterative processes; and b) may in some applications and on some engines improve engine reliability by making the iteration immune to possible engine sensor operation disruptions. In an embodiment, the number of cycles is greater than two. In an embodiment, the number of cycles is less than ten. In an embodiment, the number of cycles is between 2 and 10, inclusively. After the last cycle, the revised inlet total pressure P1R is considered sufficiently representative of the inlet total pressure P1, and thus defines the inlet total pressure P1. In another example of the system400iterating without a convergence criteria, the system400may repeat or iterate with different values for the revised inlet total pressure P1R for a fixed duration or period of time. All of the iterations or loops of the system400may be completed within a specific or fixed period (e.g. 24 ms). After the fixed period has ended, the revised inlet total pressure P1R is considered sufficiently representative of the inlet total pressure P1, and thus defines the inlet total pressure P1. In another example of the system400iterating without a convergence criteria, the system400(e.g. the delay module470) defines a cycle or scan time which establishes a limit for how long the system400has to complete one iteration or one cycle of the system and output the revised inlet total pressure P1R to the delay module470. At the end of the cycle or scan time, the delay module470outputs the revised inlet total pressure P1R to the mass flow modules410,410A. Thus, the delay module470defines the duration of one cycle or iteration of the system400. The system400will continue executing a fixed number of one or more additional instances/iterations, where each additional instance/iteration has the same cycle or scan time defined by the delay module470. After completing the fixed number of additional instances/iterations, the last revised inlet total pressure P1R will be considered sufficiently representative of the inlet total pressure P1, and thus defines the inlet total pressure P1. The iterations of the system400are thus predictable in terms of time, which may be desirable in systems like the FADEC420which may need to complete all algorithms in a prescribed time. Thus, by not using a convergence criteria, the system400may be considered to be deterministic in terms of time. This technique of iterating without a convergence criteria may reduce the load on the computer processing unit. In an embodiment, when the FADEC420is powered on, the initial inlet total pressure P1IN may not be accurate, but the revised inlet total pressure P1R may quickly become representative of the inlet total pressure P1after only one or more additional iterations of the system400. The revised inlet total pressure P1R may still be provided to other systems of the engine10even before it has become representative. In an embodiment, after a pilot has powered on the FADEC420, the revised inlet total pressure P1R may already have become representative of the inlet total pressure P1and the inlet total pressure P1determined before the pilot turns on the engine10. It can thus be appreciated that, in at least some embodiments, after the first inlet total pressure P1IN is provided, the system400is able to have the inlet total pressure obtained relatively quickly. In an embodiment, the first inlet total pressure P1IN is provided only once when the FADEC420is powered on while the engine10is on the ground. When the engine10is airborne, the system400may be run again, and will use the value for the revised inlet total pressure P1R that was generated after the last iteration and which is stored in the delay module470. Referring toFIG.4, there is disclosed a method100of determining the inlet total pressure P1of air at the air inlet11of the aircraft engine10. The method100is performed on a computing device, such as the FADEC420or other suitable device or controller. At102, the method100includes setting or determining the first inlet total pressure P1IN. This may be done, for example, while the engine10is grounded. Alternatively, step102may involve using the revised inlet total pressure P1R obtained from a previous iteration of the method100. This may be done by selecting the initial inlet total pressure P1IN from a range defined between maximum and minimum values. The first inlet total pressure P1N may be computed or used as a parameter, sometimes referred to herein as the “first parameter”. The first parameter may be any single value or multiple values that are representative of the value of first inlet total pressure P1N, and which is coded or configured to be used in the method100and system400. The method100includes performing or executing a routine or sequence that includes the following actions. The use of term “sequence” does not require the actions to be performed sequentially or in series. In an embodiment, the actions are performed sequentially or in series. In an alternate embodiment, the actions are performed non-sequentially. At104, the sequence includes determining the mass flow W1C of air passing through the air inlet11using the first parameter which is representative of the first inlet total pressure P1N, or by using a parameter representative of the revised inlet total pressure P1R from a previous iteration or cycle. This may be done, for example, using one or both of the mass flow module410and the auxiliary mass flow module410A. At106, the sequence includes determining the Mach number of air passing through the air inlet11using the mass flow W1C. This may be done, for example, using the Mach number module430. At107, the sequence includes determining the static air pressure PS1at the air inlet11. This may be done, for example, by receiving the static pressure PS1from the static pressure sensor40SP. At108, the sequence includes determining the air pressure ratio P1R/PS1E using the Mach number, where the pressure ratio P1R/PS1E is defined as the revised inlet total pressure P1R over the estimated static pressure PS1E of air at the air inlet11. At110, the sequence includes generating a subsequent parameter that is indicative of the revised inlet total air pressure P1R based on the air pressure ratio P1R/PS1E and the static air pressure PS1. The revised inlet total pressure P1R may be computed or used as a parameter, sometimes referred to herein as the “subsequent parameter”. The subsequent parameter may be any single value or multiple values that are representative of the value of revised inlet total pressure P1R, and which is coded or configured to be used in the method100and system400. Step110may include receiving the static pressure PS1of air at the air inlet11that is measured with the static pressure sensor40SP, and multiplying the pressure ratio P1R/PS1E with the static pressure PSR to obtain the revised inlet total pressure P1R. The sequence includes substituting the subsequent parameter from step110for the first parameter in step104, thereby allowing the method100to run another iteration or cycle using the revised inlet total pressure P1R. The method steps104to110forming the sequence are repeated with the subsequent parameter (i.e. the revised inlet total pressure P1R) in place of the first parameter (i.e. the first inlet total pressure P1IN), in order to obtain another revised inlet total pressure P1R. The revised inlet total pressure P1R may then be outputted as the inlet total pressure P1. In one possible configuration, and as shown at decision node112, the method100may continue to perform one or more additional instances of the sequence, using the revised inlet total pressure P1R, until the revised inlet total pressure P1R converges to the converged inlet total pressure P1C, which is then outputted as the inlet total pressure P1. The method100may output the inlet total pressure P1to the FADEC420and/or to other systems or components of the engine10. With reference toFIG.5, an example of a computing device310is illustrated. For simplicity only one computing device310is shown but the system400may include more computing devices310operable to exchange data. The computing devices310may be the same or different types of devices. The system400and/or method100may be implemented with one or more computing devices310. Note that the system400and/or method100may be implemented as part of a full-authority digital engine controls (FADEC)420or other similar device, including electronic engine control (EEC), engine control unit (ECU), electronic propeller control, propeller control unit, and the like. In some embodiments, the system400and/or method100is implemented as a Flight Data Acquisition Storage and Transmission system, such as a FAST™ system. The system400and/or method100may be implemented in part in the FAST™ system and in part in the EEC. Other embodiments may also apply. The computing device310comprises a processing unit312and a memory314which has stored therein computer-executable instructions316. The processing unit312may comprise any suitable devices configured to implement the system400and/or method100such that instructions316, when executed by the computing device310or other programmable apparatus, may cause the functions/acts/steps performed as part of the system400and/or method100as described herein to be executed. The processing unit312may comprise, for example, any type of general-purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, a central processing unit (CPU), an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, other suitably programmed or programmable logic circuits, or any combination thereof. The memory314may comprise any suitable known or other machine-readable storage medium. The memory314may comprise non-transitory computer readable storage medium, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. The memory314may include a suitable combination of any type of computer memory that is located either internally or externally to device, for example random-access memory (RAM), read-only memory (ROM), compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or the like. Memory314may comprise any storage means (e.g., devices) suitable for retrievably storing machine-readable instructions316executable by processing unit312. The methods and systems for determining the inlet total pressure described herein may be implemented in a high level procedural or object oriented programming or scripting language, or a combination thereof, to communicate with or assist in the operation of a computer system, for example the computing device310. Alternatively, the methods and systems for determining the inlet total pressure may be implemented in assembly or machine language. The language may be a compiled or interpreted language. Program code for implementing the methods and systems for determining the inlet total pressure may be stored on a storage media or a device, for example a ROM, a magnetic disk, an optical disc, a flash drive, or any other suitable storage media or device. The program code may be readable by a general or special-purpose programmable computer for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein. Embodiments of the methods and systems for determining the inlet total pressure may also be considered to be implemented by way of a non-transitory computer-readable storage medium having a computer program stored thereon. The computer program may comprise computer-readable instructions which cause a computer, or more specifically the processing unit312of the computing device310, to operate in a specific and predefined manner to perform the functions described herein, for example those described in the system400and/or method100. Computer-executable instructions may be in many forms, including program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types. Typically the functionality of the program modules may be combined or distributed as desired in various embodiments. The embodiments described herein are implemented by physical computer hardware, including computing devices, servers, receivers, transmitters, processors, memory, displays, and networks. The embodiments described herein provide useful physical machines and particularly configured computer hardware arrangements. The embodiments described herein are directed to electronic machines and methods implemented by electronic machines adapted for processing and transforming electromagnetic signals which represent various types of information. The embodiments described herein pervasively and integrally relate to machines, and their uses; and the embodiments described herein have no meaning or practical applicability outside their use with computer hardware, machines, and various hardware components. Substituting the physical hardware particularly configured to implement various acts for non-physical hardware, using mental steps for example, may substantially affect the way the embodiments work. Such computer hardware limitations are clearly essential elements of the embodiments described herein, and they cannot be omitted or substituted for mental means without having a material effect on the operation and structure of the embodiments described herein. The computer hardware is essential to implement the various embodiments described herein and is not merely used to perform steps expeditiously and in an efficient manner. The term “connected” or “coupled to” may include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). The technical solution of embodiments may be in the form of a software product. The software product may be stored in a non-volatile or non-transitory storage medium, which can be a compact disk read-only memory (CD-ROM), a USB flash disk, or a removable hard disk. The software product includes a number of instructions that enable a computer device (personal computer, server, or network device) to execute the methods provided by the embodiments. In addition, it should be noted that the system400and/or method100and, more generally, the techniques described herein can be performed substantially in real-time, during operation of the engine10. For example, if the engine10is used as part of an aircraft, the determination of the inlet total pressure P1of the engine10can be performed in real-time during a flight mission. The results of the determination can be reported to the operator and adjustments to the operational parameters of the engine10can also be performed in real-time. Thus, the computing device310can be used to dynamically determine the inlet total pressure P1of the air inlet11of the engine10in substantially real-time. The embodiments described in this document provide non-limiting examples of possible implementations of the present technology. Upon review of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made to the embodiments described herein without departing from the scope of the present technology. Yet further modifications could be implemented by a person of ordinary skill in the art in view of the present disclosure, which modifications would be within the scope of the present technology. | 67,372 |
11859562 | DETAILED DESCRIPTION OF THE INVENTION The subject disclosure is described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure such that one skilled in the art will be enabled to make and use the present invention. It may be evident, however, that the present disclosure may be practiced without some of these specific details. Broadly, one embodiment of the present invention is at least one turbine engine controller implementing a hybrid fuel governor to control the amount of fuel delivered to a turbine every frame. A frame of time is usually between 5 ms and 20 ms where the controller predicts the amount of fuel needed to consume to maintain operating conditions. Typically, turbine engine controllers implement a closed loop PID controller that monitors turbine parameters and utilizes the PID mathematical formula to calculate the needed fuel per frame but uses only one PID as a fuel governor. The present invention will utilize a series of VCPIDs4to enable the ATDEC to monitor systems not directly connected to the turbine and control their setpoints by controlling the output power of the turbine to these external set points. In general, and in accordance with the present invention, a VCPID4adds two new feedback inputs to a standard PID calculation: SELoutput2and In CNTRL3, that allows multiple VCPIDs4to work together, or in parallel.FIG.4depicts the two feedback mechanisms9and10that drive the modified PID loopFIG.2inputs2and3. In CNTRL3switches the standard PID loop between modified operation and standard operation. When TRUE3, the PID calculations inFIG.2default to normal operations. When FALSE3, the PID calculations utilize the last OUTPUT from Min Select9and feed that value10through the calculations defined in2. This moves the integral portion of the PID loop to the last output from the in control VCPID4and calculates the fuel demand for the next frame. This feedback allows for a smooth handover between VCPIDs, of which one is in control3. To take advantage of the ATDEC invention, adding an external VCPID, like well pressure8, enables the ATDEC to monitor the well pressure and automatically adjusts turbine output based on a purely external stimulus allowing for a quicker response. Being an automated system to perform the rate reducing ensures the safety of the well casing, even if the operator is distracted. This fast automatic response allows running a higher rate and higher pressures closer to the limits since any sudden increase in pressure can be detected and mitigation actions taken within milliseconds, instead of the operator response time of a few seconds. The present invention allows for a turbine control that can take over tasks typically done by operators or other control systems, providing for faster response times, smoother operations, higher reliability, and finer control than a human operator. Human operators have limited response times and can become distracted when working a highly repetitive operations for hours on end. An automated system ties to the heart of the turbine control system is more reliable at tedious operations, and quicker to respond. Certain embodiments of the present invention may include an ATDEC configured as depicted inFIG.3that will operate more efficiently than an older system as depicted inFIG.1. Certain embodiments of the present invention may include an ATDEC configured as depicted inFIG.4that will operate more efficiently than an older system as depicted inFIG.1and protect the external well. Certain embodiments of the present invention may include an ATDEC configured as depicted inFIG.4but with the addition of VCPIDs4that monitor pump sensors (oil temp, torque) and transmission sensors (oil temp, torque) to provide a fully integrated ATDEC. Certain embodiments of the present invention include a fracking pump control system such that the operator inputs both the rate and the pressure limits and the control system limits the power applied by the pump to stay within those limits and any other pre-programmed limits as indicated by expanded VCPIDs. In general, a closed loop pump controller first receives a pressure setpoint from a user (via an input device, such as a graphical user interface). This is shown, for example, inFIG.4, which illustrates a Well PSI CMD, which is set via user input. Next, the ATDEC is connected to a hardware input (e.g., WELL PSI inFIG.4) to read an analog signal. Third, the pump controller translates the user setpoint to analog scale. Once setup, adjustments are made in the fuel governor at the same rate the governor is governing turbine speed and temperature. By executing at the fuel governor level, the most efficient operation of the engine can be achieved. This is depicted inFIG.4, where the Well Pressure VCPID is running in parallel to the N1, N2, and EGT VCPIDs. All of the parallel VCPIDs are connected to two feedbacks from the output of the system. Min Select9sets the state of whether a VCPID was the lowest demand for fuel the last time the control loop executed. SEL Out10is connected to the input SEL Output2which will be used to calculate the new fuel command for all VCPIDs that were not in control3. Before or during operation, the user inputs the rate and pressure limits, which are generally a few percentage points below the allowable limits. The well head pressure transducer is constantly monitored by the control software for, if and when the pressure approaches and/or exceeds said pressure limit, reducing the pumping rate. FIG.2depicts, mathematically, how the governor (referred to herein as a VCPID) of the present invention is different so that an ATDEC with a fuel governor controlling fuel based on an external hardware analog input8(as mentioned above) is possible. As discussed in the Background, the governor1inFIG.1contains a classical PID loop, but this type of loop does not allow for multiple PID calculations in parallel. In comparison, the adapted PID loop inFIG.2defines the modifications to a PID loop that incorporates information from the PID loop in control. This adapted PID loop is referred to herein as a VCPID4. The VCPID contains two feedback points so that an external VCPID can initialize it to a current state. The first feedback point is SELoutput2, which is the output of an external VCPID that is currently in control of the fuel for the last time frame. SELoutput2uses an external VCPID integral term as current input when another VCPID is being used. The integral term in the VCPID will utilize the current ‘in charge’ VCPID leading to a seamless switch between VCPIDs. In doing so, independent governors can be tuned to very accurate performances on their own create a more efficient system. The second feedback point is “In CNTRL”3, which indicates if this VCPID is currently in control or not (i.e., whether the VCPID is controlling or utilizing an external state). In this modification to the standard PID, if this PID is NOT in control, it will initialize the integral portion of the calculation with the output of an external PID running in parallel and subtracts the previous internal derivative and proportional terms. The VCPID4has the following inputs: In CNTRL3, CMD Set Point (which is the value this governor4should control to), and CUR Value (which is the current value that should be driven to the set point). FIG.3illustrates standard turbine setup with no external sensor, but with the ability to incorporate it, since there are now three independent governors (VCPIDs5,6,7) as opposed toFIG.1, with only one governor1. Accordingly,FIG.3is similar toFIG.1, the original control, but updated to use the new VCPID4. The new implementation of the simple turbine control implements, for example, three VCPIDs4bound to the same variables as that ofFIG.1. An N1VCPID5controls fuel against N1set points and N1speed, an N2VCPID6controls fuel against N2set points and N2speed, and an EGT VCPID7controls fuel against turbine exhaust temperature set points. This modified application of the VCPID4is more fuel efficient, given that the fuel can be tuned to each parameter independently. FIG.4shows the addition of an external sensor working with parallel VCPIDS. The new VCPID allows for external control of fuel by sources that can be affected by external factors (i.e., an external parameter) other than just the turbine. By having independent VCPIDs, the turbine can be integrated into complex systems that have external forces affecting them. A Well Pressure VCPID8implements a VCPID, as described above, against well pressure that is affected by other pumps in the system. Without explicit coordination, each direct drive turbine pump utilizing the teachings of this disclosure will monitor the effects of the other pumps on well pressure and predict fuel based on that observation. In this example, a well pressure on a frac site can control the fuel and be tuned even though the well pressure is a product of rock formations, other pumps, and other factors. Those with skill in the art will appreciate that the VCPID can also be applied to other system critical sensors like torque and oil temperature. This will create a truly ‘smart turbine control’ that does not simply look at turbine operational parameters, but instead all operational parameters in an integrated system. To make various embodiments of the present invention, these algorithmic software embodiments utilize industrial standard components such as pressure transducers and digital engine controllers, which reduces the complexity of implementing the present invention. At least one of each head pressure transducer, an engine controller connected to a fracking pump are required. Multiple pressure transducers could also be placed at various points in the frack pluming (often referred to as “the iron”) which would serve to not only protect the well head, but also the pump, the missile, it's valves and other elements of the iron. In use, most commonly, the operator would enter the rate and pressure limits into the system. The pressure limit will usually be set to the well casing pressure, but other limiting factors in the iron maybe considered and input into this limit. The operator will start up the pumps and command the rate as needed for the frack job. As the fracking operation continues, commonly, the pressure will rise. If and when the pressure gets to the inputted limit, the engine will begin to limit its power to prevent the pressure form rising above the pressure limit. Additional uses include water transfer (e.g., fluid pumps) and other pipeline systems that require monitoring/managing pressure, temperature, and other parameters for safety. Therefore, the disclosed systems and methods are well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the teachings of the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined, or modified and all such variations are considered within the scope of the present disclosure. The systems and methods illustratively disclosed herein may suitably be practiced in the absence of any element that is not specifically disclosed herein and/or any optional element disclosed herein. While apparatuses and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the apparatuses and methods can also “consist essentially of” or “consist of” the various components and steps. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the elements that it introduces. If there is any conflict in the usages of a word or term in this specification and one or more patent or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted. As used herein, the phrase “at least one of” preceding a series of items, with the terms “and” or “or” to separate any of the items, modifies the list as a whole, rather than each member of the list (i.e., each item). The phrase “at least one of” allows a meaning that includes at least one of any one of the items, and/or at least one of any combination of the items, and/or at least one of each of the items. By way of example, the phrases “at least one of A, B, and C” or “at least one of A, B, or C” each refer to only A, only B, or only C; any combination of A, B, and C; and/or at least one of each of A, B, and C. | 13,770 |
11859563 | DETAILED DESCRIPTION In at least some multi-engine aircraft, such as helicopters, prior art bleed systems may not be capable of supplying an adequate flowrate and/or pressure of bleed air in some operating conditions, such as when a gas turbine engine providing the bleed air is operating in a low power, or standby mode, and not being used to provide substantive motive power to the aircraft. For the purposes of this document, the term “active” used with respect to a given engine means that the given engine is providing motive power to the aircraft. For the purposes of this document, the terms “standby” and “sub-idle” are used with respect to a given engine to mean that the given engine is operating but is providing no motive power, or at least substantially no motive power, to the aircraft, with “sub-idle” operation being a particular type of standby operation according to the present technology as described in this document. It is however understood that when operating in a “standby” mode, as used herein, the engine provides little to no motive power to the aircraft, when the standby engine is running at, below, or above, idle speed. For the purposes of the present description, the term “conduit” with respect to a fluid is used to describe an arrangement of one or more elements, such as one or more conventional hoses, connectors, filters, pumps and the like, as may be suitable for the described functionality of the conduit, and which together form the flow path(s) to provide the functionality described with respect to the conduit. For example, a given air conduit may be defined by any number and combination of air lines, filters, control actuators, and the like, selected to provide the particular functionality described with respect to the given air conduit. As another example, a given fuel conduit may be defined by any number and combination of hoses hydraulically interconnected in parallel and/or series, by or with one or more fuel filters, switches, pumps, and the like, selected to provide the particular functionality described with respect to the given fuel conduit. FIG.1illustrates an aircraft engine10of a type preferably provided for use in subsonic flight, generally comprising a shaft12operatively connectable to a fan or other rotor, such as a helicopter rotor, and, in serial flow communication, a compressor section14for pressurizing ambient air, a combustor16in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section18for extracting energy from the combustion gases. Components of the engine10are rotatable about a longitudinal center axis2of the engine10. In the present embodiment, the engine10is a turboshaft engine. It is contemplated that the engine10could be a different type of engine, such as a rotary engine, a turboprop, or a turbofan engine for example. FIG.2schematically illustrates an aircraft20, in this example a helicopter, having a first engine10′, and a second engine10″. The engines10′,10″ are operable to provide motive power to the aircraft20via conventional transmission systems and controls. For simplicity, only the non-conventional aspects of the present technology are described in detail in this document. In this embodiment, each of the engines10′,10″ is substantially the same as engine10shown inFIG.1and described above. Therefore, only the first engine10′ is described in further detail. Parts of the second engine10″ that correspond to parts of the first engine10′ are labeled with the same numerals. The illustrated exemplary multi-engine system may be used as a power plant for the aircraft20, including but not limited to a rotorcraft such as a helicopter. The multi-engine system may include the two or more gas turbine engines10′,10″. In the case of the aircraft20being a helicopter, these gas turbine engines10′,10″ will be turboshaft engines. Control of the multi-engine system shown inFIG.2is effected by one or more controller(s)20′ (shown inFIG.2only, to maintain clarity of the figures), which may be FADEC(s), electronic engine controller(s) (EEC(s)), or the like, that are programmed to manage, as described herein below, the operation of the engines10′,10″. In some embodiments and operating conditions, control sequences as described in the present application may reduce an overall fuel burn of the aircraft20, particularly during sustained cruise operating regimes, wherein the aircraft20is operated at a sustained (steady-state) cruising speed and altitude. The cruise operating regime is typically associated with the operation of prior art engines at equivalent part-power, such that each engine contributes approximately equally to the output power of the multi-engine system. Other phases of a typical helicopter mission would include transient phases like take-off, climb, stationary flight (hovering), approach and landing. Cruise may occur at higher altitudes and higher speeds, or at lower altitudes and speeds, such as during a search phase of a search-and-rescue mission. In the present description, while the aircraft20conditions (cruise speed and altitude) are substantially stable, the engines10′,10″ of the multi-engine system may be operated asymmetrically, with one engine operated in a high-power “active” mode and the other engine operated in a lower-power “standby” mode. Doing so may provide fuel saving opportunities to the aircraft, however there may be other suitable reasons why the engines are desired to be operated asymmetrically. This operation management may therefore be referred to as an “asymmetric mode” or an “asymmetric operating regime”, wherein one of the two engines is operated in a low-power “standby mode” while the other engine is operated in a high-power “active” mode. In such an asymmetric operation, which may be engaged during a cruise phase of flight (continuous, steady-state flight which is typically at a given commanded constant aircraft cruising speed and altitude). The multi-engine system may be used in an aircraft, such as a helicopter, but also has applications in suitable marine and/or industrial applications or other ground operations. Referring still toFIG.2, according to the present description the multi-engine system driving a helicopter20may be operated in this asymmetric manner, in which one of the engines10′,10″ may be operated at high power in an active mode and another one of the engines10′,10″ may be operated in a low-power standby mode. In one example, the active engine may be controlled by the controller(s)20′ to run at full (or near-full) power conditions in the active mode, to supply substantially all or all of a required power and/or speed demand of the aircraft20. The standby engine may be controlled by the controller(s)20′ to operate at low-power or no-output-power conditions to supply substantially none or none of a required power and/or speed demand of the aircraft20. Optionally, a clutch may be provided to declutch the low-power engine. Controller(s)20′ may control the engine's governing on power according to an appropriate schedule or control regime, for example as described in this document. The controller(s)20′ may be one or multiple suitable controllers, such as for example a first controller for controlling the engine10′ and a second controller for controlling the second engine10″. The first controller and the second controller may be in communication with each other in order to implement the operations described herein. In some embodiments, and a single controller20′ may be used for controlling the first engine10′ and the second engine10″. To this end, the term controller as used herein includes any one of: a single controller controlling the engines10′,10″, and multiple controllers controlling the engines10′,10″. In another example, an asymmetric operating regime of the engines may be achieved through the one or more controller's differential control of fuel flow to the engines, as described in pending application Ser. No. 16/535,256, the entire contents of which are incorporated herein by reference. Low fuel flow may also include zero fuel flow in some examples and/or times. Although various differential control between the engines of the multi-engine engine system are possible and some such sequences are described in this document, in one particular embodiment the controller(s)20′ may correspondingly control fuel flow rate to each engine10′,10″ as follows. In the case of the standby engine, a fuel flow (and/or a fuel flow rate) provided to the standby engine may be controlled to be between 70% and 99.5% less than the fuel flow (and/or the fuel flow rate) provided to the active engine. In the asymmetric mode, the standby engine may be maintained between 70% and 99.5% less than the fuel flow to the active engine. In some embodiments of the method60, the fuel flow rate difference between the active and standby engines may be controlled to be in a range of 70% and 90% of each other, with fuel flow to the standby engine being 70% to 90% less than the active engine. In some embodiments, the fuel flow rate difference may be controlled to be in a range of 80% and 90%, with fuel flow to the standby engine being 80% to 90% less than the active engine. In another embodiment, the controller29may operate one engine of the multiengine system in a standby mode at a power substantially lower than a rated cruise power level of the engine, and in some embodiments at zero output power and in other embodiments less than 10% output power relative to a reference power (provided at a reference fuel flow). Alternately still, in some embodiments, the controller(s)20′ may control the standby engine to operate at a power in a range of 0% to 1% of a rated full-power of the standby engine (i.e. the power output of the second engine to the common gearbox remains between 0% to 1% of a rated full-power of the second engine when the second engine is operating in the standby mode). In another example, the engine system ofFIG.2may be operated in an asymmetric operating regime by control of the relative speed of the engines using controller(s)20′, that is, the standby engine is controlled to a target low speed and the active engine is controlled to a target high speed. Such a low speed operation of the standby engine may include, for example, a rotational speed that is less than a typical ground idle speed of the engine (i.e. a “sub-idle” engine speed). Still other control regimes may be available for operating the engines in the asymmetric operating regime, such as control based on a target pressure ratio, or other suitable control parameters. Although the examples described herein illustrate two engines, asymmetric mode is applicable to more than two engines, whereby at least one of the multiple engines is operated in a low-power standby mode while the remaining engines are operated in the active mode to supply all or substantially all of a required power and/or speed demand of a common load. In use, the one of the engines10′,10″ may operate in the active mode while the other of the engines10′,10″ may operate in the standby mode, as described above. During this asymmetric operation, if the aircraft20needs a power increase (expected or otherwise), the active engine(s) may be required to provide more power relative to the low power conditions of the standby mode, and possibly return immediately to a high- or full-power condition. This may occur, for example, in an emergency condition of the multi-engine system powering the helicopter, wherein the “active” engine loses power the power recovery from the lower power to the high power may take some time. Even absent an emergency, it will be desirable to repower the standby engine to exit the asymmetric mode. The controller(s)20′ may also be used to operate the various air valves described herein. To this end, any suitable operative connections and configurations of controls may be provided, so long as the functionality described herein is provided. Because such operative connections may be conventional, to maintain clarity, only one such operative connection is shown schematically inFIG.2. The rest of the operative connections may be similar, and hence are not shown. As shown schematically inFIG.2, the first engine10′ includes a bleed air system27that includes air conduits22,23,24,25,26and valves22′,24′,24″, as will be seen. A first bleed air conduit22and a second bleed air conduit24are provided, both of which bleed compressed air from respective parts of the compressor section14of the first engine10′. While in this application the air sources are P2.7and P2.8, respectively, in other embodiments other locations in the compressor section14and/or other locations fluidly connected to the compressor section14may be used, for example to suit each particular embodiment and application of the engine(s)10′,10″. In the present embodiment, the first bleed air conduit22includes a check valve22′ and branches off into supply bleed air conduits23downstream of the check valve. In this embodiment, the second bleed air conduit24includes a check valve24′ and a check valve24″. The second bleed air conduit24branches off into supply bleed air conduits25at one or more locations that are fluidly in between the check valves24′,24″. As shown, the check valves24′,24″ are pointing toward each other, for purposes explained below. The supply bleed air conduits23,25deliver bleed air to various sealing and lubrication systems of the first engine10′ and/or to various locations for various aircraft functions. The particular airflow destinations may be selected to suit and/or may depend on the particular embodiment and application of the engine(s)10′,10″. The particular number and configuration of the sealing systems may be any suitable number and configuration, and is therefore not described in detail. The supply bleed air conduits23and25may also provide bleed air for various other functions of the first engine10′ and/or the aircraft. Examples of such functions include, but are not limited to, cooling of turbines, maintenance of cabin pressure, operation of air systems, and pressurizing liquid tanks. Any suitable air piping and controls arrangement may be used to provide for each particular combination of the functions provided for by the bleed air from the first and second bleed air conduits22,24. Still referring toFIG.2, the first and second bleed air conduits22,24of the first engine10′ fluidly converge/join into a common bleed air conduit26. The common bleed air conduit26fluidly connects to a control valve28. The control valve28may be any suitable one or more control valves so long as it provides for the functionality described in this document. The conduits22,23,24,25,26and valves22′,24′,24″ of the first engine10′ are part of the bleed air system27of the first engine10′. The rest of the bleed air system27may be conventional and is therefore not shown or described in detail herein. As shown inFIG.2, in the present embodiment, the bleed air system29of the second engine10″ is similar to the bleed air system27of the first engine10′, described above. Therefore, to maintain simplicity of this description, the bleed air system29of the second engine10″ is not described in detail. Suffice it to say that parts of the bleed air system29of the second engine10″ that correspond to parts of the bleed air system27of the first engine10′ are labeled with the same numerals. As shown inFIG.2, the common bleed air conduit26of the second engine10″, similar to the common bleed air conduit26of the first engine10′, fluidly connects to a control valve28. The control valve28is operable by a controller of the aircraft20to selectively: i) fluidly connect the common bleed air conduit26of the first engine10′ to the common bleed air conduit26of the second engine10″, and ii) fluidly disconnect the common bleed air conduit26of the first engine10′ from the common bleed air conduit26of the second engine10″, as illustrated by the internal structure of the control valve28schematically shown inFIG.2. The control valve28may be actuated using any suitable actuator of the engines10′,10″ and/or of the aircraft20. FIG.2shows a first in-flight, powered, mode of operation of the aircraft20during which both engines10′,10″ are “active” (a.k.a. operating in an active mode), and are therefore both providing motive power to the aircraft20. In this operating condition, the bleed air system27of the first engine10′ and the bleed air system29of the second engine10″ are both self-sufficient. For the purposes of this document, the term “self-sufficient” used with respect to a given bleed air system of a given engine means that the given bleed air system of the given engine provides all of its intended functions for the duration of the time during which it is called upon to provide for the functions. A given bleed air system of a given engine is not “self-sufficient” when one or more of the intended functions of the given bleed air system may be unavailable or unstable due to a lack of bleed air pressure and/or bleed air supply rate provided by the corresponding engine to the given bleed air system. Reference is now made toFIG.3, which shows a second in-flight, powered, mode of operation of the aircraft20during which: i) the first engine10′ is “active” and is therefore providing motive power to the aircraft20, and ii) the second engine10″ is on “standby” (a.k.a. operating in a standby mode) and is therefore not providing any material amount of motive power to the aircraft20. In this operating condition (i.e. in the second in-flight mode of operation), the bleed air system27of the first engine10′ is self-sufficient. On the other hand, depending on each particular embodiment of the engines10′,10″ and/or the aircraft20and/or on the characteristics of the particular “standby” operation of the second engine10″, the bleed air system29of the second engine10″ may or may not be self-sufficient in the standby mode. For this reason, during the second in-flight mode of operation of the aircraft20, the control valve28may be actuated by a suitable controller of the aircraft20to fluidly connect the common bleed air conduit26of the first engine10′ to the common bleed air conduit26of the second engine10″, to provide for an additional supply of bleed air from the bleed air system27of the first engine10′ to the bleed air system29of the second engine10″. Self-sufficiency of the bleed air system29of the second engine10″ may thereby be provided. After the second engine10″ is brought into an “active” state while the first engine10′ is in an “active” state, the control valve28may be actuated by a suitable controller of the aircraft20to fluidly disconnect the common bleed air conduit26of the first engine10′ from the common bleed air conduit26of the second engine10″, as shown inFIG.2. After the first engine10′ is put into a standby mode or a sub-idle mode while the second engine10″ is in an “active” mode, the control valve28may be actuated by a suitable controller of the aircraft20to fluidly connect the common bleed air conduit26of the first engine10′ to the common bleed air conduit26of the second engine10″. The bleed air system29of the second engine10″ may thereby provide compressed air to the bleed air system27of the first engine10′. Self-sufficiency of the bleed air system27of the first engine10′ may thereby be provided. The bleed air systems27,29of the engines10′,10″ and the control valve28are part of an air system30of the aircraft20. As described above, the air system30of the aircraft20implemented according to the present technology may thereby provide for self-sufficient operation of at least one of the engines10′,10″ in at least some operating conditions of the aircraft20in which at least some prior art engine bleed air systems may not be self-sufficient. Further, as shown inFIGS.2and3for example, in the present embodiment, the check valves24′ and24″ are provided in the bleed air conduits24, downstream of the branching-out bleed air conduits25. In this embodiment, this the branching-out bleed air conduits25may supply compressed air to at least some subsystems of the respective engines10′,10″. Each of the check valves24′ and24″ ensures that when the engine10′,10″ having that check valve24′,24″ is providing compressed air from its bleed air system27,29to the bleed air system27,29of the other engine10′,10″, the compressed air is provided from the air source corresponding to the bleed air conduit22of that engine10′,10″. The check valves24′ and24″ therefore help ensure uncompromised self-sufficient operation of the subsystems of the one of the engines10′,10″ that may at a given time be providing compressed air to the other one of the engines10′,10″. In some embodiments, the check valve24′ and/or the check valve24″ may be omitted. The rest of the air system30that is not shown in the figures of the present application may be conventional and is therefore not described in detail herein. Any suitable controls and any suitable control logic may be used to provide for the functionality of the air system30, and/or for various timings of actuation of the control valve28relative to switches between “active” and “standby” states that may occur with respect to each of the engines10′,10″ during in-flight or ground operations of the aircraft20. Referring now toFIG.4, an air system40of the aircraft20, which is an alternative embodiment of the air system30is shown. The air system40is similar to the air system30, and therefore similar reference numerals have been used for the air system40. A difference of the air system40from the air system30, is that air system40includes a control valve41, a control valve42, and an external compressed air source43such as an auxiliary power unit (APU) and/or an air compressor for example. The external compressed air source43may be any conventional external compressed air source suitable for each particular embodiment of the engines10′,10″ and the aircraft20. The control valve41selectively fluidly connects the external compressed air source43to the common bleed air conduit26of the first engine10′, via any suitable corresponding air conduits. More particularly, when the first engine10′ is “active”, the control valve41may be actuated by a suitable controller of the aircraft20to fluidly disconnect the external compressed air source43from the common bleed air conduit26of the first engine10′, and may thereby allow the bleed air system27of the first engine10′ to run self-sufficiently. When the first engine10′ is on “standby”, the control valve41may be actuated by a suitable controller of the aircraft20to fluidly connect the external compressed air source43to the common bleed air conduit26of the first engine10′. The control valve41may thereby provide “supplemental” compressed air to the bleed air system27of the first engine10′ at a supply rate and pressure sufficient to allow the bleed air system27of the first engine10′ to provide for all of its intended functions during the “standby” operation of the first engine10′. The control valve41, via corresponding air conduit(s), may selectively fluidly connect the external compressed air source43to a different part of the bleed air system27of the first engine10′, so long as the functionality described above is provided. The control valve42similarly fluidly connects the external compressed air source43to the common bleed air conduit26of the second engine10″, and is actuated according to a similar control logic to allow the bleed air system29of the second engine10″ to provide for all of its intended functions during the “standby” operation of the second engine10″. As shown, the control valve28that fluidly connects the bleed air system27of the first engine10′ to the bleed air system29of the second engine10″ may be in a position in which it fluidly disconnects the first engine10′ from the second engine10″, to allow for the supplemental compressed air to be provided to either one, or to both, of the engines10′,10″ by the external compressed air source43. In some embodiments, the control valves28,41,42may be actuated correspondingly to switch between the various possible supply modes of air described above. For example, in some operating conditions, the bleed air system27,29of one of the engines10′,10″ may receive “supplemental” compressed air from one or both of: i) the bleed air system27,29of another one of the engines10′,10″, and ii) the external compressed air source43. Referring now toFIG.5, an air system50of the aircraft20, which is yet another alternative embodiment of the air system30is shown. The air system50is similar to the air system40, and therefore similar reference numerals have been used for the air system50. A of the air system50difference from the air system40, is that air system50does not have a control valve28for fluidly connecting the bleed air system27of the first engine10′ to the bleed air system29of the second engine10″. Operation of the air system50is similar to operation of the air system40with respect to the external compressed air source43. In at least some embodiments and applications, the air systems30,40,50may allow to provide “supplemental” compressed air to the bleed air system27,29of one of the engines10′,10″ in at least some cases where that bleed air system27,29is malfunctioning and/or leaking air for example. A person skilled in the art will appreciate that while a particular air conduit arrangement is shown inFIGS.1to5, other air conduit arrangements may be used while providing for at least some of the functionality described in this document. While a single external compressed air source43is used in the embodiments ofFIGS.4and5, multiple different external compressed air sources may be used. Likewise, while the example aircraft20has two engines10′,10″, the present technology may be implemented with respect to more than two engines and/or with respect to other types of engines. With the above systems in mind, the present technology provides a method60of using, in flight, a source of pressurized air external to an engine of an aircraft20. As seen above, in some embodiments and operating conditions, the source of pressurized air may be one of the engines10′,10″ of the aircraft20, and in some embodiments, an APU43or air compressor43of the aircraft20. In some embodiments, the method60includes a step61of operating a given engine10′,10″ of the aircraft20during flight. In some embodiments, the method60also includes a step62of directing pressurized air from the source of pressurized air external to the given engine10′,10″, to a bleed air system27,29of the given engine10′,10″. In some embodiments, the given engine10′,10″ to which pressurized air is directed is a first engine10′ of the aircraft20, the aircraft20includes a second engine10″, and the source of pressurized air external to the first engine10′ is a bleed air system29of the second engine10″. As seen above, in some embodiments, the aircraft20is a multi-engine helicopter in which the engines10′,10″ are operatively connected to drive at least one main rotor of the helicopter to provide motive power to/propel the helicopter. As seen above, in some embodiments, the directing pressurized air to the bleed air system27of the first engine10′ is executed when the first engine10′ is operating in a standby mode. In embodiments in which the source of the pressurized air is the bleed air system29of the second engine10″, the second engine10″ is active (i.e. providing motive power to the helicopter). Similarly, in some operating conditions during flight, the given engine10′,10″ to which pressurized air is directed is a second engine10″ of the aircraft20. In some such cases, the source of pressurized air external to the second engine10″ is a bleed air system27of the first engine10′. In some such cases, the second engine10″ is in a standby mode while the first engine10′ providing the compressed air is active (i.e. providing motive power to the helicopter). As seen above, in some embodiments, the source of pressurized air is a first source of pressurized air (e.g. first engine10′ or second engine10″, depending on which of these engines is active and which is in a standby mode), the aircraft20includes a second source of pressurized air (e.g. APU/air compressor43of the aircraft20). In some such embodiments, the second source of pressurized air43is external to both the first engine10′ and the second engine10″. In some such embodiments and in some flight conditions, the method60comprises directing pressurized air from the second source of pressurized air43to the first engine10′. In some such embodiments and in some flight conditions, the method60comprises directing pressurized air from the second source of pressurized air43to the second engine10″. Further in some such embodiments and in some flight conditions, the method60comprises directing pressurized air from the second source of pressurized air43to both the first engine10′ and the second engine10″. Further with the structure of the aircraft20described above, the present technology also provides method70of operating a bleed air system27of a first gas turbine engine10′ of a multi-engine aircraft20during flight. In some embodiments, the method70comprises a step71of operating the first gas turbine engine10′ of the aircraft20during flight in a standby mode, such as an idle or a sub-idle mode that provides either no motive power or at least materially no motive power to the aircraft20. In some embodiments, the method70comprises a step71of operating a second gas turbine engine10″ of the aircraft20during flight in an active mode (i.e. providing non-substantially-zero motive power to the aircraft20). In some cases, the steps71and72are executed simultaneously. In some such cases, the method70comprises directing pressurized air from a bleed air system29of the second gas turbine engine10″ to a bleed air system27of the first gas turbine engine10′. In some cases, the method70further includes a step73of operating a source of pressurized air (E.g. APU/air compressor43, and the like) of the aircraft20external to both the first gas turbine engine10′ and the second gas turbine engine10″, and a step of directing pressurized air from the source of pressurized air43to at least one of the first gas turbine engine10′ and the second gas turbine engine10″. In some cases, the directing pressurized air from one of the bleed air systems27,29to the other one of the bleed air systems27,29(depending on which one of the bleed air systems27,29requires supplemental compressed air) may be executed simultaneously with directing pressurized air from a second source of pressurized air to the one of the bleed air systems27,29that is receiving the supplemental compressed air. In some embodiments, the second source of pressurized air43includes, or is, at least one of: an APU43of the aircraft20, and an air compressor43of the aircraft20. In some such cases, the air pressure in the one of the bleed air systems27,29receiving supplemental compressed air may be lower than the pressure of the supplemental compressed air. It is contemplated that any suitable controls and control arrangements may be used to provide for this pressure differential, where required. While two engines10′,10″ of an aircraft20are described, it is contemplated that the present technology could be implemented with regard to a larger number of engines of an aircraft to provide supplemental compressed air from one or more of the engines or other compressed air source(s), to one or more other ones of the engines. In at least some cases and in at least some embodiments, the technology described above may be implemented with, and may help provide or improve standby operation or sub-idle operation of one or more engines of a multi-engine aircraft, as described in the commonly owned U.S. Patent Application No. 62/855,062, entitled “CONTROL LOGIC FOR GAS TURBINE ENGINE FUEL ECONOMY”, filed on May 31, 2019, and incorporated by reference herein in its entirety. The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the disclosed technology. For example, while the present technology is illustrated with respect to, inter alia, bleed air systems, the present technology may also be implemented with respect to other systems of a multi-engine aircraft. For example, a fuel system of one engine of an aircraft operating in an active mode may be fluidly connectable to a fuel system of another engine of the aircraft operating in a standby mode to provide supplemental pressure to the fuel system of the other engine. As another example, an oil system of one engine of an aircraft operating in an active mode may be fluidly connectable to an oil system of another engine of the aircraft operating in a standby mode to provide supplemental pressure to the oil system of the other engine. The foregoing examples are non-limiting. | 33,159 |
11859564 | DETAILED DESCRIPTION FIG.1shows a system20that incorporates a gas turbine engine22. The gas turbine engine22has a full authority digital electronic controller (“FADEC”)24that controls all aspects of the engine including its combustor26. The gas turbine engine controller24takes signals from a plurality of components on the gas turbine engine and identifies a desired flow demand and fuel pressure dependent on conditions at the gas turbine engine. The FADEC24communicates with a fuel supply system30to demand a desired flow volume of fuel and at a desired pressure. Fuel tank28supplies fuel to a fuel pump32in the fuel supply system30. Downstream of the pump32is a metering valve34. A control36, which is part of the fuel supply system30, controls the pump32and the metering valve34such that a desired volume flow of fuel reaches a line19leading to the combustor26. Moreover, the control36controls the pump32and metering valve34such that the fuel in line19is at a desired pressure. In a feature of this disclosure, the FADEC only provides the desired volume flow and pressure to the control36. The control36is programmed to control a variable displacement pump32and the metering valve34such that the desired volume and pressure are achieved in line19. The control is supplied by the supplier of the fuel supply system30, and is calibrated by the supplier of the pump32and metering valve34. In this manner, improved accuracy is achieved. FIG.2Ashows a first embodiment variable displacement pump40. Pump40incorporates a swash plate42having an actuator44that can change the eccentricity of the swash plate42relative to a reciprocating axis of a pump piston48. The swash plate42is shown at a large volume flow position. However, the actuator44can adjust the position of the swash plate to a smaller volume position such as shown in phantom at52. The piston48moves within a cylinder50to supply fuel to a downstream line51. Although a single piston48is illustrated, in practice, there may a plurality of circumferentially spaced pistons48. A motor46drives the swash plate42to rotate. A sensor49senses the pressure and/or volume of the fuel at line51. The control36receives signals from the sensor49, and operates to control the actuator44and motor46such that the swash plate42is operated at a desired speed and at a desired eccentricity to provide the desired flow volume and pressure to the line51. The pump40is shown somewhat schematically, as the operation of a swash plate piston pump is known. FIG.2Bshows another embodiment pump53. Variable displacement pump52is a vane pump, having a motor54driving a rotor56. As known, a plurality of vanes60are driven to move along an inner surface of a liner58to move fuel from an inlet to an outlet. The liner58has an actuator57such that the eccentricity of the liner58relative to a rotational axis of the rotor56can be controlled. In this manner the displacement of the pump can be controlled. This is shown schematically, as vane pumps are well known. Control36is shown here communicating with actuator57and motor54to provide the desired volume flow and pressure downstream of the pump52. While the sensor is not illustrated here, a sensor such as shown inFIG.2Amay be provided to communicate signals back to the control36. FIG.2Cshows another embodiment70. Embodiment70includes a sharing valve72communicating flow to two pumps74and76. While two pumps are shown, of course other plural numbers of pumps may be utilized. Pump74and76may be fixed displacement pumps. Sharing valve72may also send fuel into a bypass line73leading back to a fuel tank. The control36controls the valve72and the speed of the pumps74and76to provide a desired volume of flow downstream of the pump74and76to the combustor and at a desired pressure. Here again, the operation of such system generally is known. It is the use of the controller having calibration information to control the valve72and pump74/76which is part of this disclosure. While the sensor is not illustrated here, a sensor such as shown inFIG.2Amay be provided to communicate signals back to the control36. As shown inFIG.3A, the fuel supply system30is a “line replaceable” unit. That is, the fuel supply system is received within a single housing110that can be removed as a unit. The pump32is shown as well as a cover plate136. InFIG.3Bthe cover plate136is removed and one can see the control36is received within a compartment140in the line replaceable fuel metering unit30. FIG.4shows a flow chart. At step100a signal is received from a FADEC, and that signal is FLOW=X, PRESSURE=Y. At step102the control36receives this signal and is programmed and calibrated to recognize that to achieve the flow X the pump should operate at condition A and the valve should operate at condition B. The control36is also calibrated to know that to achieve the pressure Y the pump should be operated at condition A′ and the valve operated at condition B′. At step104, the flow downstream of the fuel supply system will be such that the flow will equal X and the pressure will equal Y. In sum, by moving the specific control for the fuel supply system to a dedicated controller the accuracy of the fuel downstream of the fuel supply system meeting the demanded flow and pressure requirements will be improved. FIG.5shows another embodiment200. In embodiment200, a local control202controls a pump204, similar to theFIG.1embodiment. However, control202still receives signals from the FADEC206. However, the FADEC206directly controls the metering valve208in this embodiment. A fuel supply system includes a pump to be connected to a fuel tank. A metering valve is downstream of the pump. A control is programmed to control at least one of the pump and metering valve. The control is operable to take in a flow demand signal and a fuel pressure signal from a controller associated with a gas turbine engine. The flow demand signal is indicative of a desired flow volume and the fuel pressure signal is indicative of a desired fuel pressure. Operation conditions are identified for the at least one of said pump and the metering valve to achieve the desired flow volume and the desired fuel pressure. Although embodiments have been disclosed, a worker of skill in this art would recognize that modifications would come within the scope of this disclosure. For that reason the following claims should be studied to determine the true scope and content of this disclosure. | 6,454 |
11859565 | DETAILED DESCRIPTION OF THE DISCLOSURE FIG.1illustrates a gas turbine engine10having a principal rotational axis9. The engine10comprises an air intake12and a propulsive fan23that generates two airflows: a core airflow A and a bypass airflow B. The gas turbine engine10comprises a core11that receives the core airflow A. The engine core11comprises, in axial flow series, a low pressure compressor14, a high-pressure compressor15, combustion equipment16, a high-pressure turbine17, a low pressure turbine19and a core exhaust nozzle20. A nacelle21surrounds the gas turbine engine10and defines a bypass duct22and a bypass exhaust nozzle18. The bypass airflow B flows through the bypass duct22. The fan23is attached to and driven by the low pressure turbine19via a shaft26and an epicyclic gearbox30. In use, the core airflow A is accelerated and compressed by the low pressure compressor14and directed into the high pressure compressor15where further compression takes place. The compressed air exhausted from the high pressure compressor15is directed into the combustion equipment16where it is mixed with fuel F and the mixture is combusted. The resultant hot combustion products then expand through, and thereby drive, the high pressure and low pressure turbines17,19before being exhausted through the nozzle20to provide some propulsive thrust. The high pressure turbine17drives the high pressure compressor15by a suitable interconnecting shaft27. The fan23generally provides the majority of the propulsive thrust. The epicyclic gearbox30is a reduction gearbox. An exemplary arrangement for a geared fan gas turbine engine10is shown inFIG.2. The low pressure turbine19(seeFIG.1) drives the shaft26, which is coupled to a sun wheel, or sun gear,28of the epicyclic gear arrangement30. Radially outwardly of the sun gear28and intermeshing therewith is a plurality of planet gears32that are coupled together by a planet carrier34. The planet carrier34constrains the planet gears32to precess around the sun gear28in synchronicity whilst enabling each planet gear32to rotate about its own axis. The planet carrier34is coupled via linkages36to the fan23in order to drive its rotation about the engine axis9. Radially outwardly of the planet gears32and intermeshing therewith is an annulus or ring gear38that is coupled, via linkages40, to a stationary supporting structure24. Note that the terms “low pressure turbine” and “low pressure compressor” as used herein may be taken to mean the lowest pressure turbine stages and lowest pressure compressor stages (i.e. not including the fan23) respectively and/or the turbine and compressor stages that are connected together by the interconnecting shaft26with the lowest rotational speed in the engine (i.e. not including the gearbox output shaft that drives the fan23). In some literature, the “low pressure turbine” and “low pressure compressor” referred to herein may alternatively be known as the “intermediate pressure turbine” and “intermediate pressure compressor”. Where such alternative nomenclature is used, the fan23may be referred to as a first, or lowest pressure, compression stage. The epicyclic gearbox30is shown by way of example in greater detail inFIG.3. Each of the sun gear28, planet gears32and ring gear38comprise teeth about their periphery to intermesh with the other gears. However, for clarity only exemplary portions of the teeth are illustrated inFIG.3. There are four planet gears32illustrated, although it will be apparent to the skilled reader that more or fewer planet gears32may be provided within the scope of the claimed invention. Practical applications of a planetary epicyclic gearbox30generally comprise at least three planet gears32. The epicyclic gearbox30illustrated by way of example inFIGS.2and3is of the planetary type, in that the planet carrier34is coupled to an output shaft via linkages36, with the ring gear38fixed. However, any other suitable type of epicyclic gearbox30may be used. By way of further example, the epicyclic gearbox30may be a star arrangement, in which the planet carrier34is held fixed, with the ring (or annulus) gear38allowed to rotate. In such an arrangement the fan23is driven by the ring gear38. By way of further alternative example, the gearbox30may be a differential gearbox in which the ring gear38and the planet carrier34are both allowed to rotate. It will be appreciated that the arrangement shown inFIGS.2and3is by way of example only, and various alternatives are within the scope of the present disclosure. Purely by way of example, any suitable arrangement may be used for locating the gearbox30in the engine10and/or for connecting the gearbox30to the engine10. By way of further example, the connections (such as the linkages36,40in theFIG.2example) between the gearbox30and other parts of the engine10(such as the input shaft26, the output shaft and the fixed structure24) may have any desired degree of stiffness or flexibility. By way of further example, any suitable arrangement of the bearings between rotating and stationary parts of the engine (for example between the input and output shafts from the gearbox and the fixed structures, such as the gearbox casing) may be used, and the disclosure is not limited to the exemplary arrangement ofFIG.2. For example, where the gearbox30has a star arrangement (described above), the skilled person would readily understand that the arrangement of output and support linkages and bearing locations would typically be different to that shown by way of example inFIG.2. Accordingly, the present disclosure extends to a gas turbine engine having any arrangement of gearbox styles (for example star or planetary), support structures, input and output shaft arrangement, and bearing locations. Optionally, the gearbox may drive additional and/or alternative components (e.g. the intermediate pressure compressor and/or a booster compressor). Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. For example, such engines may have an alternative number of compressors and/or turbines and/or an alternative number of interconnecting shafts. By way of further example, the gas turbine engine shown inFIG.1has a split flow nozzle18,20meaning that the flow through the bypass duct22has its own nozzle18that is separate to and radially outside the core engine nozzle20. However, this is not limiting, and any aspect of the present disclosure may also apply to engines in which the flow through the bypass duct22and the flow through the core11are mixed, or combined, before (or upstream of) a single nozzle, which may be referred to as a mixed flow nozzle. One or both nozzles (whether mixed or split flow) may have a fixed or variable area. Whilst the described example relates to a turbofan engine, the disclosure may apply, for example, to any type of gas turbine engine, such as an open rotor (in which the fan stage is not surrounded by a nacelle) or turboprop engine, for example. In some arrangements, the gas turbine engine10may not comprise a gearbox30. The geometry of the gas turbine engine10, and components thereof, is defined by a conventional axis system, comprising an axial direction (which is aligned with the rotational axis9), a radial direction (in the bottom-to-top direction inFIG.1), and a circumferential direction (perpendicular to the page in theFIG.1view). The axial, radial and circumferential directions are mutually perpendicular. The fuel F provided to the combustion equipment16may comprise a fossil-based hydrocarbon fuel, such as Kerosene. Thus, the fuel F may comprise molecules from one or more of the chemical families of n-alkanes, iso-alkanes, cycloalkanes, and aromatics. Additionally or alternatively, the fuel F may comprise renewable hydrocarbons produced from biological or non-biological resources, otherwise known as sustainable aviation fuel (SAF). In each of the provided examples, the fuel F may comprise one or more trace elements including, for example, sulphur, nitrogen, oxygen, inorganics, and metals. Functional performance of a given composition, or blend of fuel for use in a given mission, may be defined, at least in part, by the ability of the fuel to service the Brayton cycle of the gas turbine engine Parameters defining functional performance may include, for example, specific energy; energy density; thermal stability; and, emissions including particulate matter. A relatively higher specific energy (i.e. energy per unit mass), expressed as MJ/kg, may at least partially reduce take-off weight, thus potentially providing a relative improvement in fuel efficiency. A relatively higher energy density (i.e. energy per unit volume), expressed as MJ/L, may at least partially reduce take-off fuel volume, which may be particularly important for volume-limited missions or military operations involving refuelling. A relatively higher thermal stability (i.e. inhibition of fuel to degrade or coke under thermal stress) may permit the fuel to sustain elevated temperatures in the engine and fuel injectors, thus potentially providing relative improvements in combustion efficiency. Reduced emissions, including particulate matter, may permit reduced contrail formation, whilst reducing the environmental impact of a given mission. Other properties of the fuel may also be key to functional performance. For example, a relatively lower freeze point (° C.) may allow long-range missions to optimise flight profiles; minimum aromatic concentrations (%) may ensure sufficient swelling of certain materials used in the construction of o-rings and seals that have been previously exposed to fuels with high aromatic contents; and, a maximum surface tension (mN/m) may ensure sufficient spray break-up and atomisation of the fuel. The ratio of the number of hydrogen atoms to the number of carbon atoms in a molecule may influence the specific energy of a given composition, or blend of fuel. Fuels with higher ratios of hydrogen atoms to carbon atoms may have higher specific energies in the absence of bond strain. For example, fossil-based hydrocarbon fuels may comprise molecules with approximately 7 to 18 carbons, with a significant portion of a given composition stemming from molecules with 9 to 15 carbons, with an average of 12 carbons. ASTM International (ASTM) D7566, Standard Specification for Aviation Turbine Fuels Containing Synthesized Hydrocarbons (ASTM 2019c) approves a number of sustainable aviation fuel blends comprising between 10% and 50% sustainable aviation fuel (the remainder comprising one or more fossil-based hydrocarbon fuels, such as Kerosene), with further compositions awaiting approval. However, there is an anticipation in the aviation industry that sustainable aviation fuel blends comprising up to (and including) 100% sustainable aviation fuel (SAF) will be eventually approved for use. Sustainable aviation fuels may comprise one or more of n-alkanes, iso-alkanes, cyclo-alkanes, and aromatics, and may be produced, for example, from one or more of synthesis gas (syngas); lipids (e.g. fats, oils, and greases); sugars; and alcohols. Thus, sustainable aviation fuels may comprise either or both of a lower aromatic and sulphur content, relative to fossil-based hydrocarbon fuels. Additionally or alternatively, sustainable aviation fuels may comprise either or both of a higher iso-alkane and cyclo-alkane content, relative to fossil-based hydrocarbon fuels. Thus, in some examples, sustainable aviation fuels may comprise either or both of a density of between 90% and 98% that of kerosene and a calorific value of between 101% and 105% that of kerosene. Owing at least in part to the molecular structure of sustainable aviation fuels, sustainable aviation fuels may provide benefits including, for example, one or more of a higher energy density; higher specific energy; higher specific heat capacity; higher thermal stability; higher lubricity; lower viscosity; lower surface tension; lower freeze point; lower soot emissions; and, lower CO2emissions, relative to fossil-based hydrocarbon fuels (e.g. when combusted in the combustion equipment16). Accordingly, relative to fossil-based hydrocarbon fuels, such as Kerosene, sustainable aviation fuels may lead to either or both of a relative decrease in specific fuel consumption, and a relative decrease in maintenance costs. As used herein, T30, T40, T41, P30, P40 and P41, and any other numbered pressures and temperatures, are defined using the station numbering listed in standard SAE AS755, in particular:P30=High Pressure Compressor (HPC) Outlet Total Pressure;T30=HPC Outlet Temperature;P40=Combustion Exit Total Pressure;T40=Combustion Exit Temperature;P41=High Pressure Turbine (HPT) Rotor Entry Total Pressure;T41=HPT Rotor Entry Temperature. As depicted inFIG.6, an aircraft1may comprise multiple fuel tanks50,53; for example a larger, primary fuel tank50located in the aircraft fuselage, and a smaller fuel tank53a,53blocated in each wing. In other examples, an aircraft1may have only a single fuel tank50, and/or the wing fuel tanks53may be larger than the central fuel tank50, or no central fuel tank may be provided (with all fuel instead being stored in the aircraft's wings)—it will be appreciated that many different tank layouts are envisaged and that the examples pictured are provided for ease of description and not intended to be limiting. FIG.6shows an aircraft1with a propulsion system2comprising two gas turbine engines10. The gas turbine engines10are supplied with fuel from a fuel supply system3on board the aircraft. The fuel supply system3of the example pictured comprises a single fuel source. For the purposes of the present application the term “fuel source” is understood to mean either 1) a single fuel tank or 2) a plurality of fuel tanks which are fluidly interconnected. Each fuel source is arranged to provide a separate source of fuel i.e. the first fuel source may contain a first fuel having a different characteristic or characteristics to a second fuel contained in a second fuel source. First and second fuel sources are therefore not fluidly coupled to each other so as to separate the different fuels (at least under normal running conditions). In the present example, the first fuel source comprises a centre fuel tank50, located primarily in the fuselage of the aircraft and a plurality of wing fuel tanks53a,53b, where at least one wing fuel tank is located in the port wing and at least one wing fuel tank is located in the starboard wing for balancing. All of the tanks50,53are fluidly interconnected in the example shown, so forming a single fuel source. Each of the centre fuel tank and the wing fuel tanks may comprise a plurality of fluidly interconnected fuel tanks. In another example, the wing fuel tanks53a,53bmay not be fluidly connected to the central tank50, so forming a separate, second fuel source. For balancing purposes, one or more fuel tanks in the port wing may be fluidly connected to one or more fuel tanks in the starboard wing. This may be done either via a centre fuel tank50(if that tank does not form part of the other fuel source), or bypassing the centre fuel tank(s), or both (for maximum flexibility and safety). In another example, the first fuel source comprises wing fuel tanks53and a centre fuel tank50, while a second fuel source comprises a further separate centre fuel tank (not pictured). Fluid interconnection between wing fuel tanks53and the centre fuel tank50of the first fuel source may be provided for balancing of the aircraft1. In some examples, the allocation of fuel tanks50,53available on the aircraft may be constrained such that the first fuel source and the second fuel source are each substantially symmetrical with respect to the aircraft centre line. In cases where an asymmetric fuel tank allocation is permitted, a suitable means of fuel transfer may be provided between fuel tanks of the first fuel source and/or between fuel tanks of the second fuel source such that the position of the aircraft's centre of mass can be maintained within acceptable lateral limits throughout the flight. An aircraft1may be refuelled by connecting a fuel storage vessel60, such as that provided by an airport fuel truck, or a permanent pipeline, to a fuel line connection port62of the aircraft, via a fuel line61. A desired amount of fuel may be transferred from the fuel storage vessel60to the one or more tanks50,53of the aircraft1. Especially in examples with more than one fuel source, in which different tanks50,53are to be filled with different fuels, multiple fuel line connection ports62may be provided instead of one, and/or valves may be used to direct fuel appropriately. Whilst there are standards with which all aviation fuels must be compliant, different aviation fuels have different compositions, for example depending on their source (e.g. different petroleum sources, biofuels or other synthetic aviation fuels (often described as sustainable aviation fuels—SAFs), and/or mixtures of petroleum-based fuels, and other fuels) and on any additives included (e.g. such as antioxidants and metal deactivators, biocides, static reducers, icing inhibitors, corrosion inhibitors) and any impurities. As well as varying between airports and fuel suppliers, even for a given airport or fuel supplier, fuel composition of the available aviation fuel may vary between batches. Further, fuel tanks50,53of aircraft1are usually not emptied before being topped up for a subsequent flight, resulting in mixtures of different fuels within the tanks—effectively a fuel with a different composition resulting from the mixture. The inventors appreciated that, as different fuels can have different properties, whilst still conforming to the standards, knowledge of the fuel(s) available to an aircraft1can allow more efficient, tailored, control of the propulsion system2. For example, a fuel with a higher heat capacity may be used for more engine cooling than a fuel with a lower heat capacity, and a fuel with a higher calorific value may allow a lower flow rate of fuel to be supplied to the combustor for the same power output. Knowledge of the fuel can therefore be used as a tool to improve aircraft performance. In particular, the inventors appreciated that Variable Inlet Guide Vane (VIGV) scheduling may be adjusted based on fuel characteristics. One or more fuel characteristics of a fuel arranged to be provided to a gas turbine engine10of an aircraft1may therefore be obtained or otherwise determined and used to influence control of the propulsion system2; this may be described as making an operational change to the propulsion system2. As used herein, the term “fuel characteristics” refers to intrinsic or inherent fuel properties such as fuel composition, not variable properties such as volume or temperature. Examples of fuel characteristics include one or more of:i. the percentage of sustainable aviation fuel (% SAF, by weight or volume) in the fuel, or an indication that the fuel is a fossil fuel, for example fossil kerosene, or that the fuel is a pure SAF fuel;ii. parameters of a hydrocarbon distribution of the fuel, such as:the aromatic hydrocarbon content of the fuel, and optionally also/alternatively the multi-aromatic hydrocarbon content of the fuel;the hydrogen to carbon ratio (H/C) of the fuel;% composition information for some or all hydrocarbons present;iii. the presence or percentage of a particular element or species, such as:the percentage of nitrogen-containing species in the fuel;the presence or percentage of a tracer species or trace element/substance in the fuel (e.g. a trace substance inherently present in the fuel which may vary between fuels and so be used to identify a fuel, and/or a substance added deliberately to act as a tracer);naphthalene content of the fuel;sulphur content of the fuel;cycloparaffin content of the fuel;oxygen content of the fuel;iv. one or more properties of the fuel in use in a gas turbine engine10, such as:level of non-volatile Particulate Matter (nvPM) emissions or CO2emissions on combustion (a value may be provided for a specific combustor operating under particular conditions to compare fuels fairly—a measured value may be adjusted accordingly based on combustor properties and conditions);level of coking of the fuel;v. one or more properties of the fuel itself, independent of use in an engine10or combustion, such as:thermal stability of the fuel (e.g. thermal breakdown temperature); andone or more physical properties such as density, viscosity, calorific value, freeze temperature, and/or heat capacity. For example, calorific value of a fuel may be selected as a fuel characteristic of interest. As used herein, the term “calorific value” denotes the lower heating value (also known as net calorific value) of the fuel, unless otherwise specified. The net calorific value is defined as the amount of heat released by combusting a specified quantity of the fuel, assuming that the latent heat of vaporisation of water in the reaction products is not recovered (i.e. that produced water remains as water vapour after combustion). Calorific values (also referred to as heating values) of fuels may be directly determined—for example by measuring the energy released when a certain volume or mass of the fuel is combusted in the gas turbine engine10—or calculated from other fuel parameters; e.g. based on the hydrocarbon distribution of the fuel and the calorific value of each constituent hydrocarbon type (for which a standard value may be looked up). Alternatively, or additionally so as to provide verification, the calorific value may be determined using external data, such as a look-up table for a tracer substance in the fuel, or data encoded in a barcode associated with the fuel, or other stored data. The operational change is a change to the current, or intended, operation of the propulsion system2. In particular, changes to Variable Inlet Guide Vane scheduling may be made, based on the one or more obtained fuel characteristics. For example, a variable inlet guide vane (VIGV)246, as shown inFIG.4, may be moved in a direction, and/or by an amount, determined based on the one or more fuel characteristics. Alternatively, a VIGV may be held stationary under a condition/at a time at which it would normally be moved, based on the one or more fuel characteristics being different from those of a standard or previously-used fuel. The operational change may therefore, in some instances, be a decision not to make a change to VIGV scheduling that would normally be made in the circumstances (e.g. a fuel flow rate change or aircraft speed change). Examples of operational changes therefore include adjusting, or cancelling an adjustment to, VIGV positioning. It will be appreciated that a change in VIGV geometry may generally be triggered by a change in speed of the aircraft1, a change in temperature at the inlet to a compressor14, and/or a change in pressure across a compressor14. The inventors appreciated that VIGV geometry changes may also be appropriate when a fuel with different characteristics is used—as such, when a fuel is changed in-flight (for an aircraft1with a plurality of different fuels on board) or between flights, different VIGV scheduling may be appropriate even if all engine control and environmental factors other than the fuel are the same. For example, for a given gravimetric fuel flow rate and shaft speed, the VIGVs may be opened more widely when using a fuel with a higher % SAF. Opening the VIGVs for a higher % SAF or higher calorific value fuel may do one or more of the following: improve efficiency, reduce T41, increase P30, and/or increase the overall pressure ratio across the compression system. It will be appreciated that VIGV geometry/opening angle may be measured directly, e.g. using feedback from one or more angle controllers (e.g. the actuator242described below), or may be inferred from secondary effects. Changing VIGV geometry changes the angle of flow of air into the compressor14—if one or more VIGVs246are not adjusted appropriately, the inappropriate flow can result in compressor surge or stall unless remedial action is taken (e.g. opening or closing a bleed valve, and/or making an additional operational change to the engine10). A compressor stall is a local disruption of the airflow in the compressor. A compressor surge is a stall that results in complete disruption of the airflow through the compressor14. The severity of a stall ranges from a momentary and insignificant power drop to a complete loss of compression in case of a surge, requiring adjustments to fuel flow to recover normal operation. Monitoring of pressures and flow rates enables detection of when a compressor14is approaching a surge point, and corrective action can then be taken (e.g. VIGV changes and/or bleed valve changes). A compressor14will only pump air stably up to a certain engine pressure ratio (the Engine Pressure Ratio (EPR) is the ratio of the turbine discharge pressure divided by the compressor inlet pressure); if the EPR is exceeded, the airflow will become unstable. This occurs at what is known as the surge line on a compressor map. The engine10is designed to keep the compressor14operating a small distance below the surge line, on an operating line of a compressor map. The distance between the two lines may be referred to as the surge margin. A change in fuel characteristics may raise or lower the operating pressure ratio, so moving the operating line towards or away from the surge line. If the gap between the lines/the surge margin decreases to zero, compressor stall may result. Modern compressors14are designed and controlled, usually by an electronic engine controller (EEC)42, to avoid or limit stall within an engine's operating range. FIG.4illustrates airflow A, on approach to a compressor14, and more specifically to the low pressure compressor14of the gas turbine engine10. The compressor14comprises a rotor having a plurality of blades14aextending from a central region and arranged to do work on the airflow therethrough. In the implementation depicted inFIG.4, there are a plurality of VIGVs246disposed in the working fluid flow path upstream of/at or near an entrance to the compressor14. The VIGV blade246shown is just one of a plurality of VIGVs246disposed around the fluid flow path in this example. The VIGVs246are evenly spaced around the annular flow path in the example shown, and are pivotable to adjust the angle of the VIGVs relative to the fluid flow A. VIGV arrangements may differ in other examples. In the example shown inFIG.4, the plurality of VIGVs246are coupled to a ring member244that allows the plurality of VIGVs246to move in unison. An actuator242is operatively coupled with the ring member244. The actuator242is controlled by the engine control system (EEC42) and moves the ring member244the desired amount to effect a change in position of the plurality of VIGVs246relative to the fluid flow within the working fluid path. The actuator242may also include a position-sensing feature to provide feedback on the actual position of the VIGV246. In an alternative example, a separate position sensor may be used to provide an output signal indicative of the actual position of the VIGVs246. It will be appreciated that different control and actuation arrangements may be used in different examples, for example with one or more VIGVs246being independently controllable. A VIGV scheduling manager240is used to adjust VIGV scheduling based on the one or more fuel characteristics. One or more fuel characteristics are therefore obtained for the fuel in order to perform the scheduling adjustment. For a given fuel flow rate, fuel characteristics such as the calorific value of the fuel have an effect on turbine inlet temperature, and thereby on temperatures and pressures and on the engine pressure and temperature ratios. Calorific value may therefore be selected as a, or the, fuel characteristic on which changes to VIGV scheduling are based. In some examples, such as that shown inFIG.6, the aircraft1may have only a single fuel tank50, and/or may have multiple fuel tanks50,53which each contain the same fuel, and/or are fluidly linked, or fluidly connected to the gas turbine engine10, such that only a single fuel type is supplied to the gas turbine engine10between refuelling events—i.e. the fuel characteristics may remain constant throughout a flight, and only change between flights. In other examples, however, the aircraft1may have a plurality of fluidly separate fuel tanks50,53which contain fuels of different compositions, and the propulsion system2may comprise an adjustable fuel delivery system, allowing a selection to be made of which tank(s)50,53, and therefore what fuel/fuel blend, to use. In such implementations, the fuel characteristics may vary over the course of a flight, with a specific fuel or fuel blend being provided to the gas turbine engine10. Fuel characteristics for the multiple different fuels in each tank50,53may therefore be determined, and/or fuel characteristics of a fuel/fuel blend currently being supplied to the gas turbine engine10may be directly detected or otherwise determined. Fuel characteristics, such as calorific values, may therefore be obtained in various different ways. For example:a barcode of a fuel to be added to a fuel tank50,53of the aircraft1may be scanned to read data of the fuel, ora tracer substance (e.g. a dye) identified and fuel properties looked up based on that tracer;data may be manually entered, or transmitted to the aircraft1for storage;a fuel sample may be extracted for ground-side analysis prior to take-off;fuel properties may be inferred from measurements of the propulsion system2activity during one or more periods of aircraft operation, e.g. engine start-up, taxi, take-off, climb and/or cruise; and/orone or more fuel properties may be detected onboard, optionally in-flight, for example using in-line sensors and/or other measurements. Fuel characteristics may be detected in various ways, both direct (e.g. from sensor data corresponding to the fuel characteristic in question) and indirect (e.g. by inference or calculation from other characteristics or measurements, or by reference to data for a specific detected tracer in the fuel). The characteristics may be determined as relative values as compared to another fuel, or as absolute values. For example, one or more of the following detection methods may be used:The aromatic or cycloparaffin content of the fuel can be determined based on measurements of the swell of a sensor component made from a seal material such as a nitrile seal material.Trace substances or species, either present naturally in the fuel or added to act as a tracer, may be used to determine fuel characteristics such as the percentage of sustainable aviation fuel in the fuel or whether the fuel is kerosene.Measurements of the vibrational mode of a piezoelectric crystal exposed to the fuel may be used as the basis for the determination of various fuel characteristics including the aromatic content of the fuel, the oxygen content of the fuel, and the thermal stability or the coking level of the fuel—for example by measuring the build-up of surface deposits on the piezoelectric crystal which will result in a change in vibrational mode.Various fuel characteristics may be determined by collecting performance parameters of the gas turbine engine10during a first period of operation (such as during take-off), and optionally also during a second period of operation (e.g. during cruise), and comparing these collected parameters to expected values if using fuel of known properties.Various fuel characteristics including the aromatic hydrocarbon content of the fuel can be determined based on sensor measurements of the presence, absence, or degree of formation of a contrail by the gas turbine10during its operation.Fuel characteristics including the aromatic hydrocarbon content can be determined based on a UV-Vis spectroscopy measurement performed on the fuel.Various fuel characteristics including the sulphur content, naphthalene content, aromatic hydrogen content and hydrogen to carbon ratio may be determined by measurement of substances present in the exhaust gases emitted by the gas turbine engine10during its use.Calorific value of the fuel may be determined in operation of the aircraft1based on measurements taken as the fuel is being burned—for example using fuel flow rate and shaft speed or change in temperature across the combustor16.Various fuel characteristics may be determined by making an operational change arranged to affect operation of the gas turbine engine10, sensing a response to the operational change; and determining the one or more fuel characteristics of the fuel based on the response to the operational change.Various fuel characteristics may be determined in relation to fuel characteristics of a first fuel by changing a fuel supplied to the gas turbine engine10from the first fuel to a second fuel, and determining the one or more fuel characteristics of the second fuel based on a change in a relationship between T30 and one of T40 and T41 (the relationship being indicative of the temperature rise across the combustor16). The characteristics may be determined as relative values as compared to the first fuel, or as absolute values, e.g. by reference to known values for the first fuel. In examples in which a fuel cannot be changed in flight, the VIGV scheduling manager240may be provided with one list of one or more fuel characteristics which list is then used throughout the flight/until the next refuelling event. The one or more fuel characteristics are therefore obtained just once per flight or refuelling event, and used multiple times throughout the flight, whenever a movement of VIGVs246is planned or considered. In examples in which a fuel or fuel blend can be changed in flight, the one or more fuel characteristics of fuel fed to the combustor16may change during the flight as the fuel or fuel blend is changed, so values may be obtained multiple times during a flight. For example, the VIGV scheduling manager240may obtain values for the fuel characteristics (i) at regular intervals (optionally with the frequency varying depending on stage of flight, e.g. less frequently during cruise than during climb); (ii) each time the fuel or fuel blend supplied to the gas turbine engine10is changed; and/or (iii) before each (potential) change to VIGV scheduling. The VIGV scheduling manager240may obtain data of a percentage mix of one or more different fuels being fed to the gas turbine engine10at a certain time, look up fuel characteristic data for the/each fuel in data storage, and determine/calculate fuel characteristics for the fuel/blend accordingly. In some examples, no in-flight detection or analysis may be performed, and instead pre-supplied data may be relied upon. In other examples, physical and/or chemical detection (either of the fuel characteristic(s) directly, or of one or more fuel properties or engine properties from which the fuel characteristic(s) can be derived) may be used instead of, or in addition to, data retrieval from storage. The VIGV scheduling manager240is therefore arranged to obtain one or more characteristics of the fuel currently being provided to the gas turbine engine10in any suitable way. Once one or more fuel characteristics have been determined for fuel currently being provided to the gas turbine engine10, control of the propulsion system2, and in particular VIGV scheduling, may be adjusted based on the determined fuel characteristic(s). It will be appreciated that, for many current aircraft1, VIGV scheduling changes may only be applicable to geared gas turbine engines10. For example, for a 2% increase in the calorific value of a fuel being fed to the gas turbine engine10, the VIGVs may be opened at take-off by approximately 2% of their range (assuming a full movement/rotation range of 40°). For example, for a given aircraft1with a usual VIGV angle for Jet A, the VIGVs may be opened beyond that usual angle by 5% of their range (i.e. moved by 2°) if a fuel with a calorific value 5% greater than that of Jet-A is used. This VIGV scheduling change may facilitate maintenance of a more constant turbine gas temperature (e.g. T41). A corresponding change may be made at cruise, although the magnitude of the position change is likely to be lower. It will be appreciated that VIGV scheduling changes may be tailored to a particular aircraft1, and/or to a particular part of the flight envelope (e.g. take-off or cruise), so as to achieve a certain turbine gas temperature (e.g. T41), or a certain temperature rise across the combustor16(e.g. T30-T41 relationship). By way of further example, for a 30% increase in heat capacity, the VIGVs246may be opened by an additional 0.5% at take-off, up to a limit of 5% of their full range. This may be scaled linearly for a smaller (or larger) change in heat capacity. A corresponding change may be made at cruise, although the magnitude of the change is likely to be lower. Similarly, a 30% decrease in heat capacity may prompt a 0.5% closing of the VIGVs246at take-off, up to a limit of 5% of their full range. Additional data may be used in conjunction with the determined fuel characteristics to adjust control of the VIGVs246. For example, the approach being described may comprise receiving data of operational parameters such as speed of the aircraft, air and/or fuel flow rate, temperature at the inlet to a compressor14, and/or pressure across a compressor14, fuel temperature data and/or environmental parameters such as altitude. These received data (e.g. operational and/or environmental parameters) may be used to make or influence changes in VIGV scheduling. For example, if fuel temperature were higher on entry to the combustor16, for every 50 degree increase in fuel temperature at take-off, the VIGVs246may be opened by 1% A propulsion system2for an aircraft1may therefore comprise one or more variable inlet guide vanes—VIGVs—246through/past which airflow into the compressor14passes; and a VIGV scheduling manager240arranged to obtain one or more characteristics of the fuel being provided to the gas turbine engine10; and make a change to scheduling of the one or more VIGVs246based on the one or more obtained characteristics of the fuel. The VIGV scheduling manager240may determine a desired change to VIGV scheduling based on the one or more obtained fuel characteristics and control an actuator242so as to move the one or more VIGVs246accordingly. In the implementation shown inFIG.4, a separate VIGV scheduling manager240is provided for each gas turbine engine10. In other implementations, only a single VIGV scheduling manager240may be provided, and may control VIGV scheduling for both (or all) engines10. The VIGV scheduling manager240of the example shown also includes a receiver241arranged to receive data relating to fuel composition and/or requests for VIGV scheduling changes. The determination of a desired VIGV scheduling change may therefore be performed by the VIGV scheduling manager240itself, or the VIGV scheduling manager240may implement a change determined by another entity, depending on the implementation. A fuel composition tracker202may be used to record and store fuel composition data, and optionally also to receive sensor data (and optionally other data) and to calculate fuel characteristics based on that data. The VIGV scheduling manager240may be provided as part of the same entity, or may obtain data from the fuel composition tracker202. The fuel composition tracker202of the example being described comprises memory202a(which may also be referred to as computational storage) arranged to store the current fuel characteristic data, and processing circuitry202carranged to calculate updated values for the one or more fuel characteristics of the fuel in the fuel tank50,53after refuelling. The calculated values may then replace the previously-stored fuel characteristic data in the memory, and/or may be time- and/or date-stamped and added to the memory. A log of fuel characteristic data with time may therefore be assembled. The fuel composition tracker202of the example shown also includes a receiver202barranged to receive data from which fuel characteristics may be calculated, and/or the fuel characteristics themselves, and/or requests for fuel composition information. The fuel composition tracker202of the example shown forms a part of, or is in communication with, an electronic engine controller (EEC)42. The EEC42may be arranged to issue propulsion system control commands based on the calculated fuel characteristics. It will be appreciated that an EEC42may be provided for each gas turbine engine10of the aircraft1, or a single EEC42may control both, or all, engines10. Further, the role played by the EEC for the fuel composition tracker202may be just a small part of the functionality of the EEC. Indeed, the fuel composition tracker202may be provided by the EEC, or may comprise an EEC module distinct from the engine's EEC42in various implementations. In alternative examples, the fuel composition tracker202may not comprise any engine control functionality, and may instead simply supply fuel composition data on demand, to be used as appropriate by another system. Optionally, the fuel composition tracker202may supply a proposed change in engine control functionality for approval by a pilot (or other authority); the pilot may then implement the proposed change directly, or approve or reject the automatic making of the proposed change. The propulsion system2may therefore include an electronic engine controller42arranged to issue propulsion system control commands based on the determined fuel characteristics, the fuel characteristics being determined based on data provided by the fuel composition tracker202and/or the VIGV scheduling manager240and optionally other data. The VIGV scheduling manager240of the example shown may be a part of, or be in communication with, the electronic engine controller (EEC)42which is arranged to issue propulsion system control commands based on the fuel characteristics. It will be appreciated that the role played by the EEC42for the VIGV scheduling manager240may be just a small part of the functionality of the EEC. Indeed, the VIGV scheduling manager240may be provided by the EEC42, or may comprise an EEC module distinct from the engine's EEC42in various implementations. In alternative examples, the VIGV scheduling manager240may not comprise any engine control functionality, and may instead provide VIGV scheduling data on demand, to be used as appropriate by another system. The fuel composition tracker202and/or the VIGV scheduling manager240may be provided as a separate unit built into the propulsion system2, and/or as software and/or hardware incorporated into other aircraft control systems such as the EEC42. Fuel composition tracking abilities may be provided as part of the same unit or package as engine control functionality. The EEC42, which may also be thought of as a propulsion system controller, may make changes to the propulsion system2, and in particular to VIGV scheduling, directly, or may provide a notification to the pilot (or other authority) recommending the change, for approval. In some examples, the same propulsion system controller42may automatically make some changes, and request others, depending on the nature of the change. In some examples, the same implementation may include automatically making some changes, and requesting others, depending on the nature of the change. In particular, changes which are “transparent” to the pilot—such as internal changes within engine flows which do not affect engine power output and would not be noticed by a pilot—may be made automatically, whereas any changes which the pilot would notice may be notified to the pilot (i.e. a notification appearing that the change will happen unless the pilot directs otherwise) or suggested to the pilot (i.e. the change will not happen without positive input from the pilot). In implementations in which a notification or suggestion is provided to a pilot, this may be provided on a cockpit display of the aircraft and/or as an audible alarm, and/or sent to a separate device such as a portable tablet or other computing device. A method3010of controlling a propulsion system2of an aircraft1may therefore be implemented, the propulsion system2comprising a gas turbine engine10with one or more VIGVs246at or near the entrance to a compressor14of the gas turbine engine10. The method3010comprises obtaining3012one or more characteristics of the fuel being provided to the gas turbine engine10. The obtaining3012may be performed by retrieving data from storage and/or by physically and/or chemically detecting one or more fuel properties. The obtaining step3012may be performed just once, for example on refuelling or at the start of a flight. Particularly in examples in which a fuel or fuel blend can be changed in flight, the obtaining step3012may be performed repeatedly over the course of a flight. The method3010comprises making3014a change to scheduling of the one or more VIGVs246based on the one or more obtained characteristics of the fuel, for example by moving a VIGV by a certain amount (e.g. a rotation of a certain angle), in a certain direction. In implementations with a variable fuel in flight, the obtaining step3012and the step3014of making a change based on the obtained data may be repeated together each time a change in VIGV position is considered, or the obtaining step3012may be performed at intervals. In implementations with a single, constant fuel in flight, the obtaining step3012may be performed only once and the step3014of making a change may be performed multiple times over the course of a flight, using the same obtained data. Alternatively, the obtaining step3012may again be performed at intervals, e.g. for verification. As described above, the inventors appreciated that knowledge of the fuel(s) available to an aircraft1can allow more efficient, tailored, control of the propulsion system2—such as for the VIGV scheduling control described herein. In some cases, fuel characteristics may be supplied to the aircraft1by a third party, e.g. by a supplier on refuelling. However, in other cases, prior knowledge of fuel characteristics may not be available. One or more fuel characteristics of a fuel arranged to be provided to a gas turbine engine10of an aircraft1may therefore be determined on board the aircraft1, and optionally then used to influence control of the propulsion system2. In the examples described below, the aircraft's propulsion system2is used to perform an “experiment” so as to determine, or provide data useful in the determination of, one or more fuel characteristics. This performance of an “experiment” comprises making an operational change to the propulsion system2and determining what effect that operational change has—one or more fuel characteristics can then be determined from the response to the known operational change. The fuel characteristics may include one or more of those listed above. More specifically, an operational change is made, the operational change being effected by a controllable component of the propulsion system2. The operational change is selected to affect operation of the gas turbine engine10in a manner dependent on at least one fuel characteristic. The operational change is a change to the current, or intended, operation of the propulsion system2. For example, a variable inlet guide vane (VIGV)246may be moved, and a response to that movement detected. Alternatively, a VIGV may be held stationary under a condition/at a time at which it would normally be moved, and a response to that change from the standard operational procedure may be monitored. The operational change may therefore, in some instances, be a decision not to make a change to operation that would normally be made in the circumstances. It will be appreciated that this may be thought of as the inverse of the approach3012,3014described above—rather than obtaining one or more fuel characteristics and changing VIGV scheduling based on those fuel characteristics to achieve a desired response, a change is made to VIGV scheduling and one or more fuel characteristics are inferred or determined from the response to that scheduling change. For example, VIGVs246may be moved so as to maintain a constant T41 or T30-T41 relationship on changing fuel (e.g. T41 minus T30 or T40 minus T30, indicative of a combustor temperature rise); the movement required to maintain the constant temperature or temperature relationship may then be used to identify a change in calorific value between the initial fuel (prior to the change in fuel fed to the gas turbine engine10) and the new fuel. Assuming that mass fuel flow is held constant on changing fuel, an increase in temperature rise across the combustor16(T40−T30) is likely to be seen on changing to a fuel with a higher calorific value if no VIGV scheduling changes are made. If a decision is made not to change VIGV scheduling on changing fuel/on seeing temperature rise start to increase, the change in the temperature rise across the combustor16may be used to calculate the change in fuel calorific value. For current SAFs and SAF-blends, a change of temperature rise of at least 2% or 3% may be seen as compared to kerosene, which may correspond to a change of more than 30° C., or more than 50° C. If low pressure shaft speed/thrust is held constant instead of mass flow of fuel, a rise in T41 may still be observed due to the higher calorific value of the new fuel if no VIGV scheduling changes are made, and the size of that change may be used to infer the change in calorific value. A change of around 3° C. may be observed for each 3% change in fuel calorific value. As described above, a compressor14will only pump air stably up to a certain engine pressure ratio (the Engine Pressure Ratio (EPR) is the ratio of the turbine discharge pressure (P42) divided by the compressor inlet pressure (P26)); if the EPR is exceeded, the airflow will become unstable. This occurs at what is known as the surge line on a compressor map. The engine is designed to keep the compressor operating a small distance below the surge line, on an operating line of a compressor map. The distance between the two lines may be referred to as the surge margin. A change in fuel characteristics may raise or lower the operating pressure ratio, so moving the operating line towards or away from the surge line. If the gap between the lines/the surge margin decreases to zero, compressor stall may result. Modern compressors14are designed and controlled, usually by the EEC42, to avoid or limit stall within an engine's operating range. Whilst compressor surge is generally to be avoided completely, the precise point at which a minor stall occurs for a given fuel flow rate may be used to infer fuel characteristics. The compressor14will then recover to normal flow once the engine pressure ratio reduces to a level at which the compressor can sustain stable airflow. For example, for a given fuel flow rate, the calorific value of the fuel has an effect on turbine inlet temperature, and thereby on the engine pressure and temperature ratios. Monitoring how close the compressor14comes to stall after changing the VIGV geometry, or after changing fuel and not changing the VIGV geometry, may therefore allow a calorific value or other parameter of the fuel to be determined or inferred. Whilst airflow patterns may be measured in some implementations, VIGV angles, and secondary effects such as temperature and pressure changes may be easier to measure directly. For example, as well as changes in the T30-T41 relationship, opening VIGVs246often results in a higher P30 and an increase in overall pressure ratio across the compression system. Further, VIGV position information may be directly available from one or more actuators242. Other examples of operational changes, aside from VIGV scheduling changes, may include adjusting, or cancelling an adjustment to one or more of:fuel composition (e.g. varying a % mixture of fuels from two different sources/tanks50,53);fuel temperature (e.g. of fuel entering the combustor16) or one or more other features of heat management;engine thrust;fuel flow rate;fuel pump spill ratio; andwater injection into the combustor16. For example, if a change in fuel is made whilst the gas turbine10is held to operate at a fixed speed/thrust and the fuel mass flow has dropped but the volumetric flow has not, then the new fuel can be inferred to have a lower density, and the density may be calculated accordingly. It will be appreciated that, for many current flow rate sensors, a change in flow rate may be more accurate than an absolute value, so allowing density to be calculated more accurately on changing fuel, by reference to values for the first fuel, than might be possible using the sensor flow rate values for one fuel alone. By way of further example, if air flow and/or oil flow to one or more air-oil heat exchangers118is reduced on changing fuel and no increase in pressure (or a smaller pressure increase than would be expected for the original fuel) is seen across all or a part of the fuel system3and/or if no fuel temperature change (or a smaller fuel temperature change than would be expected for the original fuel) is seen, the new fuel may be inferred to have a better heat capacity and/or thermal stability (the lack of pressure increase indicating a lack of carbon deposit formation). (The fuel system3comprises the fuel path between the tanks50,53and the engine(s)10, including all pipelines and components along that route.) It will be appreciated that reducing air flow to the air-oil heat exchanger118(which may be referred to as an air cooler) would result in less cooling of the oil and resultantly less heat removal from the engine10, and so a warmer engine10and more heat in the fuel, and that reducing oil flow to the air-oil heat exchanger118may cause more hot oil to be directed to a fuel-oil heat exchanger (not shown), so directly adding heat to the fuel. By way of further example, in a gas turbine engine10comprising a combustor16with multiple different combustion modes, a change in nvPM generation may be monitored when a change is made between combustor modes—the observed change in nvPM generation may be used to determine one or more fuel characteristics, e.g. SAF percentage or nvPM generation potential itself. Multiple operational changes may be made simultaneously, or sequentially, and the behaviour of the propulsion system2may be monitored over a period of time, gathering data to determine the one or more fuel characteristics of interest. In some examples, the aircraft1may have only a single fuel tank50, and/or may have multiple fuel tanks50,53which each contain the same fuel, and/or are fluidly linked, or fluidly connected to the gas turbine engine10, such that only a single fuel type is supplied to the gas turbine engine10between refuelling events—i.e. the fuel characteristics may remain constant throughout a flight. In other examples, the aircraft1may have a plurality of fuel tanks50,53which contain fuels of different compositions, and the propulsion system2may comprise an adjustable fuel delivery system, allowing a selection to be made of which tank(s)50,53, and therefore what fuel/fuel blend, to use. In such examples, the fuel characteristics may vary over the course of a flight, and a specific fuel or fuel blend may be selected to improve operation at certain flight stages or in certain external conditions. In such examples, the same operational change may be performed at multiple different times, with an active fuel management system214being arranged to change the fuel, or fuel blend, in between. Fuel characteristics for the multiple different fuels on board may therefore be determined. For example, in implementations in which the fuel temperature on entry to the combustor16is changed, a response to this operational change may be or comprise (i) a change in power output from the gas turbine engine10; or (ii) a change in fuel degradation or coking. Once one or more fuel characteristics have been determined for fuel currently being provided to the gas turbine engine10, control of the propulsion system2may be adjusted based on the determined fuel characteristics. Additional data may be used in conjunction with the determined fuel characteristics to adjust control of the propulsion system2. For example, the method may comprise receiving data of current conditions around the aircraft1(either from a provider, such as a third-party weather-monitoring company, or from on-board detectors). These received data (e.g. weather data, temperature, humidity, presence of a contrail, etc.) may be used to make or influence changes in propulsion system control. Instead of, or as well as, using “live” or near-live weather data, forecast weather data for the aircraft's route may also be used to estimate current conditions. By way of further example, in implementations in which the propulsion system2comprises a plurality of non-fluidly-linked fuel tanks50,53, the making an operational change may comprise or consist of changing from which tank50,53fuel is taken, or changing what percentage of fuel is taken from a particular tank, thereby changing the fuel composition. The response to a change in fuel composition may consist of or comprise one or more of the below examples:(i) a change in power output from the gas turbine engine10;(ii) a change in fuel degradation or coking;(iii) a change in contrail formation (contrails may be detected visually and/or by an infra-red sensor, or may be inferred from measurements of temperature, pressure, and humidity, amongst other variables, for example);(iv) a change in the Engine Pressure Ratio;(v) a change in the relationship between a compressor exit temperature—T30—and a turbine rotor entry temperature—T41;(vi) a change in the relationship between a compressor exit total pressure—P30—and a turbine rotor entry total pressure—P41. In the examples being described, a turbine17of the engine10comprises a rotor having a leading edge and a trailing edge. A turbine rotor entry temperature—T41—is defined as an average temperature of airflow at the leading edge of the rotor of the turbine17at cruise conditions. Similarly, a turbine rotor entry pressure—P41—is defined as the total pressure of airflow at the leading edge of the rotor of the turbine17at cruise conditions. The engine10also comprises a compressor15having an exit, and a compressor exit temperature—T30—is defined as an average temperature of airflow at the exit from the compressor15at cruise conditions. Similarly, a compressor exit pressure—P30—is defined as the total pressure of airflow at the exit from the compressor15at cruise conditions. In some examples, the gas turbine engine10comprises multiple compressors; the compressor exit temperature or pressure may be defined as the temperature or pressure at the exit from the highest pressure compressor15. The compressor15may comprise one or more rotors each having a leading edge and a trailing edge; the compressor exit temperature or pressure may be defined as the temperature or pressure at the axial position of the trailing edge of the rearmost rotor of the compressor. Between station40(combustor exit) and station41(inlet to the high pressure turbine17) there is generally provided a set of nozzle guide vanes that can be moved to modify the flow into the rotating turbine17; these are often described as variable inlet guide vanes—VIGVs246—as described above. Once one or more fuel characteristics have been determined for fuel currently being provided to the gas turbine engine, control of the propulsion system2may be adjusted based on the determined fuel characteristics. Additionally or alternatively, a planned flight profile may be changed based on the one or more determined fuel characteristics. As used herein, the term “flight profile” refers to the operational characteristics (e.g. height/altitude, power setting, flight path angle, airspeed, and the like) of an aircraft1as it flies along a flight track, and also to the trajectory/flight track (route) itself. Changes of route are therefore included in the term “flight profile” as used herein. Additional data may be used in conjunction with the determined fuel characteristics to adjust control of the propulsion system2and/or changes to the flight profile, as described above with respect to control of the propulsion system2. Once the one or more fuel characteristics of the resultant fuel in the fuel tank50,53after refuelling have been determined, the propulsion system2can be controlled based on the calculated fuel characteristics. For example:An operating parameter of a heat management system of the aircraft (e.g. a fuel-oil heat exchanger or an air-oil heat exchanger118) may be changed, or the temperature of fuel supplied to the combustor16of the engine10can be changed.When more than one fuel is stored onboard an aircraft1, a selection of which fuel to use for which operations (e.g. for ground-based operations as opposed to flight, for low-temperature start-up, or for operations with different thrust demands) or at what time during a flight may be made based on fuel characteristics such as % SAF, nvPM generation potential, viscosity, and calorific value. A fuel delivery system may therefore be controlled appropriately based on the fuel characteristics.One or more flight control surfaces of the aircraft1may be adjusted so as to change route and/or altitude based on knowledge of the fuel.The spill percentage of a fuel pump (i.e. the proportion of pumped fuel recirculated instead of being passed to the combustor) may be changed, e.g. based on the % SAF of the fuel. The pump and/or one or more valves may therefore be controlled appropriately based on the fuel characteristics.Changes to the scheduling of variable-inlet guide vanes (VIGVs246) may be made based on fuel characteristics. The VIGVs246may therefore be moved, or a movement of the VIGVs be cancelled, as appropriate based on the fuel characteristics. A propulsion system2for an aircraft1may therefore comprise a fuel composition tracker202arranged to record and store fuel composition data, and optionally also to receive data of an operational change and measurement data relating to a response to the operational change and to calculate one or more fuel characteristics based on that data (and optionally also based on other data, such as measurement data relating to responses to one or more other operational changes, or reference tables). The fuel composition tracker202may be provided as a separate fuel composition tracking unit built into the propulsion system2, and/or as software and/or hardware incorporated into the pre-existing aircraft control systems. Data from the fuel composition tracker202may be used to adjust control of the propulsion system2, based on the one or more fuel characteristics. In the example shown, two sensors204are provided, each arranged to physically and/or chemically detect one or more features of gas turbine engine performance. In different implementations, different numbers and/or types of sensors may be provided. For example, one or more pressure and/or temperature sensors204may be provided, a fuel flow rate sensor may be provided, and/or one or more chemical sensors may be provided, e.g. to detect exhaust characteristics or fuel components. The sensors204and the fuel composition tracker202together may be described as a fuel composition tracking system203, as shown inFIG.8. In some implementations, pre-existing sensors may be used such that implementing the method2090described below may not require any hardware changes. In other implementations, one or more additional sensors may be added to the propulsion system2. The fuel composition tracking system203comprises a fuel composition tracker202, or other fuel composition determination module210. The fuel composition tracker202of the example being described comprises memory202aarranged to store the current fuel characteristic data, and processing circuitry202carranged to calculate updated values for the one or more fuel characteristics of the fuel being combusted in the engine10. The calculated values may then replace the previously stored fuel characteristic data in the memory, and/or may be time- and/or date-stamped and added to the memory. A log of fuel characteristic data with time may therefore be assembled. In other implementations, a log might not be kept and indeed instantaneous control decisions may be made without storing the fuel composition data for a prolonged period. In such implementations, the term fuel composition determination module210may be preferred over fuel composition tracker202, as past data may not be tracked—the terms may otherwise be used synonymously. In the implementation shown inFIG.6, a separate fuel composition determination module210is provided for each gas turbine engine10. In other implementations, only a single fuel composition determination module210may be provided. The fuel composition tracker202,210of the example shown also includes a receiver202barranged to receive data relating to fuel composition and/or requests for fuel composition information. The propulsion system2may include an electronic engine controller42arranged to issue propulsion system control commands based on the determined fuel characteristics, based on data provided by the fuel composition tracker202and optionally other data. The fuel composition tracker202of the example shown may be a part of or be in communication with the electronic engine controller (EEC)42, and the EEC42may be arranged to issue propulsion system control commands based on the fuel characteristics. It will be appreciated that an EEC42may be provided for each gas turbine engine10of the aircraft1, and/or that the role played by the EEC42in or for the fuel composition tracker202may be just a small part of the functionality of the EEC. Indeed, the fuel composition tracker202may be provided by the EEC42, or may comprise an EEC module distinct from the engine's EEC42in various implementations. In alternative examples, the fuel composition tracker202may not comprise any engine control functionality, and may instead simply supply fuel composition data on demand, to be used as appropriate by another system. The fuel composition tracker202may be provided as a separate propulsion system controlling unit built into the propulsion system2, and/or as software and/or hardware incorporated into other aircraft control systems. Fuel composition tracking abilities may be provided as part of the same unit or package as engine control functionality, or separately. The EEC42, which may also be thought of as a propulsion system controller, may make changes to the propulsion system2directly, or may provide a notification to the pilot recommending the change, for approval, as discussed above. In some examples, the same propulsion system controller42may automatically make some changes, and request others, depending on the nature of the change, as discussed above. The propulsion system controller42may also provide recommendations regarding flight profile changes. Alternatively or additionally, the propulsion system2may further comprise a flight profile adjustor arranged to change a planned flight profile based on the one or more fuel characteristics of the fuel, and optionally other data. The flight profile adjustor may be provided as a separate propulsion system controlling unit built into the propulsion system2, and/or as software and/or hardware incorporated into the pre-existing aircraft control systems. Fuel composition tracking abilities may be provided as part of the same unit or package. A method2090of determining one or more fuel characteristics of a fuel provided to a gas turbine engine10of an aircraft1may therefore be implemented, the gas turbine engine10forming part of a propulsion system2. The method2090comprises making2092an operational change, the operational change being brought about by a controllable component of the propulsion system2and arranged to have a measurable effect on operation of the gas turbine engine10. The operational change is any suitable change to operation of the propulsion system which will have an effect on operation of the gas turbine engine10, and may be or comprise moving a component of the propulsion system2(e.g. moving a VIGV, changing pump speed, diverting fuel, and/or opening a bleed valve), or may be or comprise not moving a component of the propulsion system2in a situation in which, following normal operational procedures, it would normally be moved. The operational change may be temporary, and may be reversed as soon as enough time has elapsed for any effect on operation of the gas turbine engine10to be sensed (noting that a time interval may be left to allow for any transient effects to subside in some cases, as described in more detail below). The method2090further comprises sensing2094a response to the operational change—for example a change in one or more pressures, temperatures, shaft speeds, and/or ratios such as the engine pressure ratio. Alternatively or additionally, the change may be a change in contrail formation, coking, or any other suitable engine parameter. The response over time may be assessed instead of, or as well as, looking at values at set time-points before and after the change. The method2090further comprises determining2096the one or more fuel characteristics of the fuel being combusted by the gas turbine engine10based on the response to the operational change. In some implementations, the method2090may further comprise making2098one or more changes to aircraft operation and/or planned flight profile after the determination2096is made, based on the determined fuel characteristic(s), for example so as to improve engine efficiency or reduce climate impact (e.g. by adjusting contrail formation). In other implementations, the knowledge of fuel characteristics may not be used to change aircraft operation, but may be used to influence refuelling choices and/or to verify that fuel data supplied for a fuel are correct. In cases of a significant mismatch between the determined fuel characteristics and expected fuel characteristics, the aircraft1may be returned to a refuelling station for checking of the fuel, and/or supplemental checks may be performed. The EEC42may be arranged to provide a warning/alert to a pilot in such scenarios. In some implementations, the “experiment” may therefore be performed very early in aircraft operation—e.g. during engine warm-up and/or other pre-taxi operations, or during the early stages of taxiing, so as to facilitate return to a refuelling station if required. The operational change made at step2092may temporarily have a (generally minor) detrimental effect on engine operation; for example decreasing efficiency or pushing the propulsion system2closer to the bounds of its operating envelope—such a temporary detrimental effect on engine operation may be acceptable due to the improvements to engine performance which may then be made once the fuel characteristics are known; optimising engine performance for the fuel type. In some implementations, the operational change made at step2092may be made whilst the engine10is idling with the aircraft1on the ground, such that operation in flight is never detrimentally impacted. In implementations with multiple fuel sources, the fuel or blend supplied to the engine10may be changed during idle to allow one or more fuel characteristics of each stored fuel to be determined and stored for future reference. In implementations in which a fuel composition tracker202as described above is used to perform the method2090, the fuel composition tracker202may be arranged to:receive information regarding an operational change, the operational change being effected by a controllable component of the propulsion system2and arranged to affect operation of the gas turbine engine10;receive data corresponding to a response to the operational change; anddetermine one or more fuel characteristics of the fuel arranged to be provided to the gas turbine engine10based on the response to the operational change, as determined from the received data. In the examples described hereinbelow, one or more temperatures and/or pressures within the gas turbine engine10(and optionally a relationship between temperatures and/or pressures at different points within the gas turbine engine10) are used to determine, or provide data useful in the determination of, one or more fuel characteristics of the fuel currently being combusted in the engine10. In particular, in examples using one or more temperatures, each temperature or the temperature relationship is noted for a first fuel, and then noted again after a change in the fuel. A difference in the fuel characteristics, e.g. an increased calorific value, may therefore be determined from a difference in the temperature(s) or temperature relationship. Instead of “performing an experiment” for a single fuel currently being combusted, the fuel change is the difference, and a response to the fuel change is used to determine one or more fuel characteristics. For example, T41, or a relationship between T30 and T41, may change depending on the % SAF of a fuel if automatic VIGV adjustment (e.g. to keep T41 or the temperature relationship constant) is cancelled or delayed. A change of around 5° C. in T41 may occur, for example, if changing between kerosene and a currently used SAF. It will be appreciated that VIGV scheduling may be traditionally based on maintaining a constant level of one or more of T40, T41, T30, or the T30-T41 relationship, and that allowing temperature to change and seeing by how much, rather than automatically moving VIGVs246, may allow fuel characteristics to be inferred. Changes in the temperature(s) or in a temperature relationship may be used to identify relative fuel characteristics, rather than absolute values—e.g. an 8% increase in calorific value as compared to the previous, or reference, fuel—in some examples. In other examples, absolute values may be calculated, optionally by reference to data which may include absolute values for the previous or reference fuel. One or more pressures might also change—in some cases, pressures and temperatures may both be monitored, and a sensed change in one used to verify a sensed change in the other. In additional or alternative examples using pressures, one or more pressures and/or a pressure relationship is noted for a first fuel, and then noted again after a change in the fuel. A difference in the fuel characteristics, e.g. an increased calorific value, may therefore be determined from a difference in the pressure(s) or pressure relationship. As for temperature changes, changes in the pressure(s) may be used to identify relative fuel characteristics, rather than absolute values—e.g. an 8% increase in calorific value as compared to the previous, or reference, fuel—in some examples. In other examples, absolute values may be calculated, optionally by reference to data for the previous or reference fuel. In various examples, both pressures and temperatures are sensed, measured, calculated, or otherwise inferred, and both may be used in determining fuel characteristics. The propulsion system2may comprise one or more variable inlet guide vanes—VIGVs246—and also a fuel pump. No change to the position of VIGVs246and/or to the fuel flow rate may be made on changing fuel, at least until after updated temperature and/or pressure data have been collected, so as to allow monitoring of any change in the temperature(s) and/or pressure(s) with minimal interference/minimal variation of engine control beyond fuel type. Multiple temperature relationships, between multiple gas turbine engine temperatures, may be used in some examples. In additional or alternative examples, multiple pressure relationships, between multiple gas turbine engine pressures, may be used. In the examples being described, combustion equipment16, for example being or comprising a combustor16, combusts the fuel within the gas turbine engine10. The combustor16has an exit, and a combustor exit temperature—T40—is defined as an average temperature of airflow at the combustor exit at cruise conditions. Similarly, a combustor exit pressure—P40—is defined as the total pressure of airflow at the combustor exit at cruise conditions. Airflow from the combustor16then enters a turbine17. In the examples being described, a turbine17of the engine10comprises a rotor having a leading edge and a trailing edge. A turbine rotor entry temperature—T41—is defined as an average temperature of airflow at the leading edge of the rotor of the turbine17at cruise conditions. Similarly, a turbine rotor entry pressure—P41—is defined as the total pressure of airflow at the leading edge of the rotor of the turbine17at cruise conditions. The engine also comprises a compressor15having an exit, and a compressor exit temperature—T30—is defined as an average temperature of airflow at the exit from the compressor15at cruise conditions. Similarly, a compressor exit pressure—P30—is defined as the total pressure of airflow at the exit from the compressor15at cruise conditions. In some examples, the gas turbine engine10comprises multiple compressors14,15; the compressor exit temperature or pressure may be defined as the temperature or pressure at the exit from the highest pressure compressor15. The compressor15may comprise one or more rotors each having a leading edge and a trailing edge; the compressor exit temperature or pressure may be defined as the temperature or pressure at the axial position of the trailing edge of the rearmost rotor of the compressor. One or more of the listed temperatures and/or pressures is used to determine one or more fuel characteristics. A change in a relationship between T41 and T30, and/or between P41 and P30, may be used to determine the one or more fuel characteristics. T40 or P40 may be used in addition to, or instead of, T41 or P41 in some examples. In various implementations, cooling air that is at T30 temperatures may be introduced across a nozzle guide vane at the exit of the combustor16, between the T40 and T41 stations. In some implementations, especially in implementations in which the amount of cooling air added varies, T40 may be selected in place of T41 to avoid any variability in T41 due to the amount of cooling air influencing the relationship/temperature changes. As mentioned above, T30, T41, P30, and P41 and any other numbered pressures and temperatures listed herein are defined using the station numbering listed in standard SAE AS755, in particular:P30=High Pressure Compressor (HPC) Outlet Total PressureT30=HPC Outlet TemperatureP40=Combustion Exit Total PressureT40=Combustion Exit TemperatureP41=High Pressure Turbine (HPT) Rotor Entry Total PressureT41=HPT Rotor Entry Temperature In current engines10, T40 and T41 are generally not measured directly using conventional measurement technology, such as thermocouples, due to the high temperature. A direct temperature measurement may be taken optically but, alternatively or additionally, T40 and/or T41 values may instead be inferred from other measurements (e.g. using readings from thermocouples used for temperature measurement at other stations and knowledge of the gas turbine engine architecture and thermal properties). The relationship between pressure or temperature values at station30and at station40or41depends on how the engine10is being controlled/on what parameter is being held constant. For example, for an engine10running at a fixed (gravimetric) fuel flow rate, T41 would generally increase with the introduction of SAF, or a blend including more SAF, due to the generally higher calorific value. This change in T41 (or equivalently in T40) is then followed by a corresponding increase in shaft speeds and in T30/P30. After the transient changes in the relationship on the change in fuel type, the steady state T30-T41 relationship may return to its initial status. If instead the engine10is run with a fixed shaft speed, fuel mass flow drops when a higher calorific value fuel is used, and the core flow goes up. After the transient changes in the relationship on the change in fuel mass flow rate, the steady state T30-T41 relationship may again return to its initial status. In examples in which relative temperatures and/or pressures (temperature or pressure relationships) are used, a change in the relationship between the temperatures and/or pressures over time around the change of fuel may be used to infer or calculate one or more fuel characteristics, instead of, or as well as, looking at a ratio of, or difference between, the selected temperatures or pressures at a single point in time before the change and a single point in time after the change. Information may therefore be gleaned from the transient behaviour. In some examples, the aircraft1may have only a single fuel tank50, and/or may have multiple fuel tanks50,53which each contain the same fuel, and/or are fluidly linked, or fluidly connected to the gas turbine engine10, such that only a single fuel type is supplied to the gas turbine engine10between refuelling events—i.e. the fuel characteristics may remain constant throughout a flight. In such examples, the change in the temperature(s) and/or pressure(s) may therefore be noted based on saved data for an earlier flight (since the last refuelling event) or an earlier stage of the same flight compared to current data, rather than taking pressure and/or temperature data before and after a change made during the same flight. Additionally or alternatively, temperature and/or pressure relationship data for a reference, or standard, fuel may be supplied and current data compared to that. However, it will be appreciated that, due to the number of potential variables involved and the possibility of some sensor data not being precise (e.g. fuel flow rate), it may be preferable to use data from immediately before and after a given change in the determination described (allowing for any transients), and/or from over the course of the fuel change (including transient behaviour), so as to minimise uncontrolled variables and/or changes in environmental parameters. The examples currently being described may therefore have particular utility in examples with at least two fuel sources. In such examples, the aircraft1may have a plurality of fuel tanks50,53which may contain fuels of different compositions, and the propulsion system2may comprise an adjustable fuel delivery system, allowing a selection to be made of which tank(s)50,53, and therefore what fuel/fuel blend, to use. In such examples, the fuel characteristics may vary over the course of a flight. The temperature(s) and/or pressure(s) may be checked every time a change in the fuel is made, so as to allow properties of the current fuel to be determined. Alternatively, the temperature(s) and/or pressure(s) may be checked only when switching to a new tank50,53, or new fuel blend, for which fuel characteristics have not previously been determined and stored. In such examples, the temperature and/or pressure monitoring may be performed at multiple different times, with an active fuel management system214being arranged to change the fuel, or fuel blend, in between. Fuel characteristics for the multiple different fuels F1, F2onboard may therefore be determined. The changing of the fuel supplied to the gas turbine engine10may be performed at cruise, so as to allow the monitoring of the temperature(s) and/or pressure(s) to be performed under relatively constant conditions, such that the change of fuel is effectively the only change. This may allow more accurate determination of any change in the temperature and/or pressure relationship(s). Similarly, the changing of the fuel supplied to the gas turbine engine10may be performed at ground idle, for example before take-off. Again, this may provide relatively constant conditions, such that the change of fuel is effectively the only change. The temperature(s) and/or pressure(s) may therefore be monitored in two different time periods—one each for the two different fuels F1, F2, or over a single time period including the change of fuel. The change in fuel may be the only change made to engine control between the two time periods/over the single time period. Where two separate time periods are used, the two time periods may also be selected such that altitude and/or other external parameters are at least substantially the same for both, and may therefore be selected to be close to each other in time, if not immediately consecutive. An interval may be left between the two time periods to allow for any transient behaviour around the change in fuel. Similarly, where a single time period is used, it may be selected to be short enough for altitude and/or other external parameters to be at least substantially the same throughout. When changes are assessed between two separate time periods, as described above, it may be desirable to have the first and second time periods as close together as reasonably possible—a small interval may be left to ensure a complete change of fuel in the combustor16and allow for any transient effects to pass. (In other implementations, the transient behaviour itself may be used to determine the one or more fuel characteristics.) The required interval size (if any) may depend on fuel flow rate at the operating condition. The gas turbine engine10generally reacts almost instantly (within a second) to differences in fuel once that fuel reaches the combustor16, and speed probes used for shaft speed measurements generally have a low time constant. At relatively low power, low fuel flow rate conditions, an interval of around ten seconds from when the fuel entering the pylon which connects the engine10to the airframe of the aircraft1changes may be used. At higher power, where fuel flow rate may be four or more times higher, and interval of 2-3 seconds from fuel change on pylon entry may be appropriate. It will be appreciated that travel time from a fuel tank to the engine10may vary based on tank location as well as fuel flow rate, and can be accommodated accordingly with knowledge of the specific aircraft1—pylon entry is therefore mentioned here for ease of generalisation, although time change from opening or closing of a valve at or near a fuel tank or activation or deactivation of a fuel pump108, may be used in various implementations, with the interval calculated with reference to fuel flow time between the point of interest and the engine10. Further, measurements may be averaged over a period of time (e.g. 5 seconds up to 30 seconds) within each time period, or in the second time period only, and any trends examined, to check that a new steady state has been reached and/or to improve reliability. Based on knowledge of the fuel characteristics, a specific fuel or fuel blend may be selected to improve operation at certain flight stages or in certain external conditions. Additional data may be used in conjunction with the determined fuel characteristics to adjust control of the propulsion system2and/or changes to the flight profile. For example, the method may comprise receiving data of current conditions around the aircraft1(either from a provider, such as a third-party weather-monitoring company, or from onboard detectors). These received data (e.g. weather data, temperature, humidity, presence of a contrail, etc.) may be used to make or influence changes in propulsion system control. Instead of, or as well as, using “live” or near-live weather data, forecast weather data for the aircraft's route may also be used to estimate current conditions. As used herein, the term “flight profile” refers to the operational characteristics (e.g. height/altitude, power setting, flight path angle, airspeed, and the like) of an aircraft as it flies along a flight track, and also to the trajectory/flight track (route) itself. Changes of route (even of just 100 m or so) are therefore included in the term “flight profile” as used herein. Examples of options for control of the propulsion system2based on knowledge of fuel characteristics include those listed above. A propulsion system2for an aircraft1may therefore comprise a fuel composition tracker210arranged to record and store fuel characteristic data, and optionally also to receive measurement data relating to temperatures and/or pressures within the gas turbine engine10, and determine one or more fuel characteristics based on that data (the determination optionally involving calculating a temperature and/or pressure relationship between multiple temperatures or pressures, respectively) and optionally other data, such as measurement data relating to responses to one or more operational changes (non-limiting examples of suitable operational changes are listed above). The fuel composition tracker210may be provided as a separate fuel composition tracking unit210built into the propulsion system2, and/or as software and/or hardware incorporated into the pre-existing aircraft control systems. Data from the fuel composition tracker210may be used to adjust control of the propulsion system2, based on the one or more fuel characteristics. A plurality of temperature and/or pressure sensors204may be provided in selected locations within the gas turbine engine10. In the examples being described, multiple sensors are provided for each location of interest, optionally being symmetrically arranged around the turbine rotor entry, for example, so as to provide improved accuracy of the temperature and/or pressure measurements obtained. In the example shown, two sensors204are provided, each arranged to detect one or more pressures or temperatures relating to gas turbine engine performance—the sensors may measure one or more of P30, T30, P40, T40, P41, and T41 directly, or may provide other measurements from which one or more of those values can be calculated or inferred. In different implementations, different numbers and/or types of sensors may be provided, as described above. The sensors204and the fuel composition tracker202together may be described as a fuel composition tracking system203, as shown inFIG.8, and a fuel composition tracking system203and EEC42may be as described above. A method2010of determining one or more fuel characteristics of a fuel provided to a gas turbine engine10of an aircraft1may therefore be implemented, the gas turbine engine10forming part of a propulsion system2. The method2010comprises changing2012the fuel supplied to a gas turbine engine10of an aircraft1. The change2012may be made during operation of the aircraft1—e.g. by using a fuel management system214to take fuel from a different tank50,53—or between different sessions of operation of an aircraft1—e.g. on refuelling an aircraft1with a new fuel. The fuel change may be temporary, and may be reversed as soon as enough time has elapsed for any effect on the temperature(s) and/or pressure(s) to be sensed. The method2010further comprises sensing2014a response to the change of fuel, and in particular sensing, determining, or inferring a change to at least one selected temperature and/or pressure. Optionally two or more temperatures or pressures may be sensed, such that a relationship between P30 and one or more of P41 and P40, or T30, and one or more of T41 and T40, may be determined based on sensor data. For example, a change in one or more of the listed pressures and/or temperatures may be sensed directly or inferred/determined/calculated from other measurements and knowledge of the engine10. The method2010further comprises determining2016one or more fuel characteristics of the fuel being combusted by the gas turbine engine10based on the response to the fuel change. For example, a percentage change in calorific value between the first fuel (prior to the change) and the second fuel may be determined, so as to provide knowledge of relative fuel properties, and/or an actual calorific value may be determined (either directly, or using knowledge of values for the first fuel). The fuel change2012, and the following steps of the method2010, may be repeated to confirm the obtained fuel characteristics. In some implementations, the method2010may further comprise making2018one or more changes to aircraft operation and/or to a planned flight profile after the determination2016is made, based on the determined fuel characteristic(s), for example so as to improve engine efficiency or reduce climate impact (e.g. by adjusting contrail formation). In other implementations, the knowledge of fuel characteristics may not be used to change aircraft operation, but may be used to influence refuelling choices and/or to verify that fuel data supplied for a fuel are correct. In cases of a significant mismatch between the determined fuel characteristics and expected fuel characteristics, the aircraft1may be returned to a refuelling station for checking of the fuel, and/or supplemental checks may be performed. The EEC42may be arranged to provide a warning/alert to a pilot in such scenarios. In implementations in which a fuel composition tracker202,210as described above is used to perform some or all of the method2010, the fuel composition tracker202,210may be arranged to receive data corresponding to a change in one or more of T30, P30, T40, T41, P40 and P41; and determine one or more fuel characteristics of the fuel based on the change in the temperature(s) and/or pressure(s). In some cases, the fuel composition tracker202,210may be arranged to:receive data corresponding to a change in a relationship between T30 (or P30) and one of T40 and T41 (or one of P40 and P41); anddetermine one or more fuel characteristics of the fuel based on the change in the temperature and/or pressure relationship. In examples with two or more fuel sources, the propulsion system2may further comprise a fuel management system, e.g. fuel manager214, arranged to change the fuel supplied to the gas turbine engine10in flight; for example by actively selecting a particular tank50,53, or particular fuel blend from multiple tanks, in flight. A propulsion system controller (e.g. the EEC42) may be used to adjust control of the propulsion system2based on the one or more fuel characteristics of the fuel, based on data provided by the fuel composition tracker202and optionally other data. The propulsion system controller42may be provided as a separate propulsion system controlling unit built into the propulsion system2, and/or as software and/or hardware incorporated into the pre-existing aircraft control systems. Fuel composition tracking abilities may be provided as part of the same unit or package. As described above, the propulsion system controller42may make changes to the propulsion system directly, or may provide a notification to the pilot recommending the change, for approval. In some examples, the same propulsion system controller42may automatically make some changes, and request others, depending on the nature of the change, as discussed above. The propulsion system controller42may also provide recommendations regarding flight profile changes. Alternatively or additionally, the propulsion system2may therefore comprise a flight profile adjustor arranged to change the planned flight profile based on the one or more fuel characteristics of the fuel, and optionally other data. The flight profile adjustor may be provided as a separate propulsion system controlling unit built into the propulsion system2, and/or as software and/or hardware incorporated into the pre-existing aircraft control systems such as the EEC42. Fuel composition tracking abilities may be provided as part of the same unit or package. It will be understood that the invention is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein. | 97,001 |
11859566 | DETAILED DESCRIPTION OF THE INVENTION While the specification concludes with claims defining the features of the invention that are regarded as novel, it is believed that the invention will be better understood from a consideration of the description in conjunction with the drawings. As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the inventive arrangements in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting but rather to provide an understandable description of the invention. As described herein, a “unit,” and a “component” are used interchangeably to describe one or more identified physical objects and/or devices which are linked together and/or function together to perform a specified function. As described herein, a “powertrain resource request” can include an instruction to initiate, change or stop an operation of a powertrain component such as the engine speed, engine RPM, engine torque, and/or transmission mode/gear, for example. As described herein, an “error notification” can include a detection by the multiplex system or other life safety system that a system fault exists and/or that a configuration of components is not in the necessary order to allow new or continued operation of a life safety system. Various embodiments of an emergency vehicle throttle management system100are described below for understanding the inventive concepts disclosed herein. In each of the drawings, identical reference numerals are used for like elements of the invention or elements of like function. For the sake of clarity, only those reference numerals are shown in the individual figures which are necessary for the description of the respective figure. As described herein, a “safety interlock system” and derivatives thereof shall refer to a set of one or more electrical states representing the operating conditions of one or more life safety system components as being ordered in a logical sequence and/or configuration to allow safe or prevent unsafe operator control of the engine to change the operating speed of a coupled water pump. FIGS.2and3illustrate one embodiment of an emergency vehicle throttle management system100, having a system controller110for managing powertrain resource requests, resolving potential system conflicts, and for allowing an on-site operator to selectively engage control of the vehicle powertrain when needed to operate a specific life safety system. As shown, the controller110can include a main body111for housing a processor112that is conventionally connected to a memory113, a powertrain connection component114, a Multiplex communication component115, an internal throttle source circuit116, a throttle rule management unit117, a plurality of life safety connectivity components118a-118z, and a power module119. Although illustrated as separate elements, those of skill in the art will recognize that one or more system controller components may comprise or include one or more printed circuit boards (PCB) containing any number of integrated circuit or circuits, for completing the activities described herein. Of course, any number of other analog and/or digital components capable of performing the below described functionality can be provided in place of, or in conjunction with the below described controller elements. The main body111can include any number of different shapes and sizes and can be constructed from any number of different materials suitable for encompassing each of the controller elements. In one preferred embodiment, the main body111can be constructed from plastic having a plurality of internal connectors (not shown) for securely housing each of the device elements in a compact, shockproof, and watertight manner. Of course, any number of other known construction materials are also contemplated. The processing unit112can be one or more conventional central processing units (CPU) or any other type of device, or multiple devices, capable of manipulating or processing information such as program code stored in the memory113and/or the throttle source116and throttle rules117modules and for causing the circuitry to complete the activities and functionality described herein. The memory113can act to store operating instructions in the form of program code for the processor112to execute. Although illustrated inFIG.3as a single component, memory113can include one or more physical memory devices such as, for example, local memory and/or one or more bulk storage devices. As used herein, local memory can refer to random access memory or other non-persistent memory device(s) generally used during actual execution of program code, whereas a bulk storage device can be implemented as a persistent data storage device such as a hard drive, for example, containing programs that permit the processor to perform the functionality described below. Additionally, memory113can also include one or more cache memories that provide temporary storage of at least some program code in order to reduce the number of times program code must be retrieved from the bulk storage device during execution. Each of these devices are well known in the art. The powertrain connection component114can include circuitry that converts/formats operating instructions from the controller processor into CAN messages for transmission to a designated component and/or ECU of the vehicle powertrain system. To this end, the powertrain connection component can include a Can Bus port, or other such device for receiving a communication cable180such as a J1939 Can-Bus data cable that engages the vehicle's Controller Area Network. Of course, any number of other connection ports, cables and/or components are also contemplated. The multiplex communication component115can function to communicatively link the controller110to the onboard multiplex system5, via a command bus184, for example, to allow the system controller to receive a report indicating the vehicle's current status. As previously noted, the multiplex system5captures discrete input/output data from a plurality of nodes/sensors and interlocks positioned along the vehicle. Exemplary data which can be received includes, for example, park/drive/neutral transmission status, parking brake status, suppression fluid status, aerial ladder status, pump switch on/off status and the like. Of course, any number of other connection ports, cables and/or components are also contemplated for allowing one- or two-way communication between the multiplex system5and the system controller110. The internal throttle source circuit116can be provided as a discrete circuit or as a memory component, that includes logic for allowing the controller110to send resource requests to the vehicle powertrain system4. These powertrain resource requests can include, for example, an instruction to engage the vehicle engine, which is communicatively linked with a life safety system, and to operate the engine throttle at a set RPM, a set speed, or a set torque, for example, along with ceasing to operate the vehicle engine. The resource requests sent via the circuit116can be generated in response to a request for throttle adjustment/control from one of the life safety systems, and/or an on-site user operating an emergency throttle pedal40or other such device. In either instance, such resource commands can function to permit new or continued operation of a life safety system that is mechanically coupled to the vehicle powertrain, despite the presence of a fault or misconfiguration detected by the multiplex system5and reported to the communication component115. The throttle rule management unit117can be provided as a discrete circuit or as a memory component including a predetermined and/or programmable set of rules configured to evaluate and permit a powertrain resource request that is received from one of the life safety systems to be sent to the powertrain via the throttle source circuit116. To this end, the unit117can determine when it is permissible for the internal throttle source circuit116to obtain exclusive control of the powertrain system4despite the presence of an error notification (e.g., system fault, network fault, and/or configuration error) reported by the multiplex system5and/or a contrary instruction from the multiplex system or other life safety system. The life safety connectivity components118a-118zcan each function to communicate directly with one or more of the onboard life safety systems, such as the illustrated fire suppression system2and the aerial implement system3, via any number of different communication cables132. To this end, each of the components118a-118zcan include, comprise or consist of any device capable of creating a communications link (e.g., wired and/or wireless, serial communications interfaces, bus connector, etc.) between the system110and the life safety systems. The power module119can function to supply the necessary power requirements to each component of the system controller110. In various embodiments, the power module can include connections for engaging the onboard power supply of the vehicle and/or may include an onboard battery to permit continued operation of the system in the event the connection to the vehicle power is interrupted or unavailable. In operation, the throttle system controller110can be communicatively coupled with each of the vehicle power system4, the multiplex system5, and any number of onboard life safety systems2and3, for example, to allow the system controller110to selectively control the powertrain system4and/or to permit the life safety system to obtain or retain control of the powertrain system even if the multiplex system5or one of the other life safety systems reports an error or misconfiguration status. FIG.4schematically illustrates one embodiment of an emergency throttle system100and controller110in operation. As noted above, when the vehicle is configured to operate the fire suppression system, the vehicle PTO4awill be mechanically linked to the suppression system pump2c, and the engine/throttle4dwill be controlled by the control station2dand the pressure governor control subsystem2evia the multiplex system. During this operation, the system controller110will continue to monitor all connected systems. In the event that an error is detected, such as a failure of node5e1, for example, the system controller110can selectively take control of the powertrain system, thus preventing the multiplex system5from disabling the ongoing operation of the engine4dand pump2cthat is actively discharging water and/or provide manual override throttle control to a user. For example, if a specific rule covering the exemplary failure is programmed within the rule management unit117, the system controller110may automatically assume exclusive control of the powertrain system and may transform and convey throttle adjustment requests from the pressure governor2edirectly to the engine4d. In addition to the above, the system100can provide options for allowing an on-site user to manually control the powertrain in order to supply operating power to a life safety system. Such a feature being particularly beneficial in instances where a preset rule is not available. In such a situation, a user can instruct the system controller110to enable manual control of the engine throttle4dusing the vehicle's throttle (accelerator) pedal40and/or foot (service) brake inputs, for example. Upon receiving the user command, the system controller can transform instructions received from the operator pedals and send a powertrain resource request to the engine throttle control4dfeeding the pump2c. Although described above with regard to “manual” control, the preferred embodiment of the system controller110can employ throttle control logic in order to prevent dangerous changes in water pressure resulting from inadvertent and/or extreme throttle commands. For example, if a user suddenly applies full throttle, the system controller may gradually increase the throttle from zero to the maximum allowable throttle amount over a period of time such as 30 seconds, for example. Likewise, if a user removes their foot from the pedal40, the system controller110can gradually reduce the throttle from the current operating parameter to zero over a period of 5-10 seconds, for example. The throttle control logic can be provided as a function of the throttle source circuitry and/or the throttle rule management, and represents an important safety feature, as drastic changes in water pressure can cause equipment damage and/or serious injuries or death to firefighters and other users operating hoses and other fire suppression system components. Although described above with regard to a specific system error, this is for illustrative purposes only, as the system100may be configured for allowing the system controller110to obtain exclusive control of the powertrain system in any number of different circumstances, and such control may be implemented automatically and/or manually. As to a further description of the manner and use of the present invention, the same should be apparent from the above description. Accordingly, no further discussion relating to the manner of usage and operation will be provided. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a system, method or computer program product. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module,” “unit” or “system.” Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon. The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. | 15,933 |
11859567 | DETAILED DESCRIPTION Following below are more detailed descriptions of methods, apparatuses, and systems for modifying skip-fire CDA operation based on various thresholds to maintain operation of an injector associated with a cylinder of an engine system. The methods, apparatuses, and systems introduced above and discussed in greater detail below may be implemented in any of numerous ways, as the described concepts are not limited to any particular manner of implementation. Examples of specific implementations and applications are provided primarily for illustrative purposes. According to the present disclosure, methods, apparatuses, and systems are disclosed that modify skip-fire CDA operation of a cylinder of an engine. During CDA mode, one or more cylinders are deactivated/inactive (i.e., combustion does not occur), such that power from the engine is provided from less than all of the cylinders. In some situations, one or more of the air intake valves may be closed so to not allow air for combustion to flow into the cylinder thereby preventing combustion. In other situations, air may be allowed to flow through the cylinder but combustion is prevented via no spark or diesel fuel injection. Cylinder deactivation mode is a broad term that encompasses various related but distinct cylinder deactivation operating modes. A first type of CDA operating mode is known as “fixed cylinder CDA.” In fixed cylinder CDA, the same cylinder(s) are active/inactive each engine cycle during the fixed cylinder CDA operating mode. A second type of CDA operating mode is known as “skip-fire” operating mode. In skip-fire CDA mode, one or more cylinders are deactivated/inactive (e.g., combustion does not occur) on a cycle-by-cycle basis, such that power from the engine is provided from less than all of the cylinders. Accordingly, a cylinder may be inactive for a first engine cycle and active for a second engine cycle. An “active” cylinder means that combustion is allowed to occur in that cylinder. An “inactive” cylinder means that combustion is not allowed to occur in that cylinder. The present disclosure is applicable with each type of CDA operating mode, and the term “skip-fire mode” or “skip-fire CDA mode” is used to indicate herein that each type of operating mode is possible/applicable with the associated concept(s). In contrast and as referred to herein, the term “non-skip-fire mode” is used to refer to operation of the engine where each of the cylinders of the engine are active (able to experience to a combustion event) or the engine is operating in a fixed cylinder CDA mode. When a cylinder is inactive for an extended period, various complications may arise that impact the operation of the cylinder and engine system overall. The temperature of the tip of the fuel injector may rise to temperatures sufficient to cause coking (e.g., components of fuel and combustion products adhere to the internal surfaces of the fuel injector, causing a clog or decrease in performance). Coking may also be caused by an excessive amount of static fuel and/or a high temperature of static fuel located in the inactive injector. Furthermore, lack of lubrication within the injector may prevent the fuel injector from operating properly when subsequently activated. According to the present disclosure and as described in more detail herein, a system and method of operating an engine in a CDA operating mode is utilized to avoid the complications described. In operation, various thresholds indicative of performance and/or determined or estimated operating conditions of a fuel injector are utilized to determine whether a potential issue or complication may exist with the fuel injector (e.g., presence of coking, etc.). A controller coupled to the fuel injector may monitor characteristics of the fuel injector and compare those characteristics to the various thresholds. Based on the comparison, the controller may alter/change operation of the CDA mode to prevent a potential complication. One of the thresholds may include a temperature of the fuel injector tip. If the controller determines that a temperature of the fuel injector tip is greater than a threshold temperature, the controller may activate the cylinder to reduce the temperature of the fuel injector tip. Another threshold may include an amount or temperature of static fuel located in the fuel injector. If the controller determines that the amount or temperature of static fuel located in the fuel injector is greater than a threshold amount or threshold temperature, the controller may activate the cylinder to reduce the amount or temperature of static fuel in or proximate to the injector. Yet another threshold may include a lubrication level of the injector. If the controller determines that the injector has less lubricant than a threshold amount of lubricant, the controller may activate the cylinder to introduce additional lubricant to effectively lubricate the injector. As used herein, the term “lubricant” refers to fuel and/or fuel additives that enhance lubrication for, as an example, the injector needle. It should be understood that while the description and Figures herein is primarily directed to skip-fire CDA mode that this description is not meant to be limiting. The systems, methods, and apparatuses described herein are also applicable with other CDA operating modes (e.g., fixed cylinder CDA). Referring now toFIG.1, an illustration of a controller122coupled to a system100for skip-fire CDA operation is shown, according to an exemplary embodiment. In one embodiment, this system is implemented in a vehicle. The vehicle may include an on-road or an off-road vehicle including, but not limited to, line-haul trucks, mid-range trucks (e.g., pick-up trucks), cars, boats, tanks, airplanes, locomotives, mining equipment, and any other type of vehicle that may utilize a CDA mode. The vehicle may include a powertrain system, a fueling system, an operator input/output device, one or more additional vehicle subsystems, etc. The vehicle may include additional, less, and/or different components/systems, such that the principles, methods, systems, apparatuses, processes, and the like of the present disclosure are intended to be applicable with any other vehicle configuration. It should also be understood that the principles of the present disclosure should not be interpreted to be limited to vehicles; rather, the present disclosure is also applicable with stationary pieces of equipment such as a power generator or genset. While not shown, the system100is used with an engine system. The engine of the engine system may be structured as any internal combustion engine (e.g., compression-ignition or spark-ignition), such that it can be powered by any fuel type (e.g., diesel, ethanol, gasoline, etc.). The engine system may include an air intake system and exhaust aftertreatment system. The exhaust aftertreatment system may be configured to treat exhaust gas emissions to obtain more environmentally friendly emissions (e.g., reduce particulate matter or NOx emissions). In some alternate embodiments, the engine system may be used with a hybrid vehicle. The system100is shown to include a cylinder head104, a fuel injector assembly102, an intake valve118, an exhaust valve120, and the controller122. As described herein, various thresholds may be used to determine whether to maintain a skip-fire CDA mode or deactivate the skip-fire CDA mode to avoid potential complications of the system100. The cylinder head104may be located at the top of the engine system (e.g., above the cylinders of the engine system) and provides a housing for various components of the engine system (e.g., the fuel injector assembly102, the intake valve118, the exhaust valve120, sensors such as temperature and fuel sensors, and various other components not shown that may be a part of the engine system). The cylinder head104is positioned on top (furthest from ground surface) of a cylinder block. The cylinder head couples to the cylinder block to form a closed cylinder that is a combustion chamber. A piston is disposed in each closed cylinder and reciprocates during operation of the engine. The intake valve118is positioned within the cylinder head104and is configured to selectively open to permit air to enter the cylinder and to close to prevent air from entering the cylinder. The exhaust valve120is positioned within the cylinder head104and is configured to open to permit exhaust gases to exit the cylinder after combustion has occurred. In non-skip-fire mode operation, both the intake valve118and the exhaust valve120selectively open and close during cylinder cycles to allow air to enter the cylinder, undergo combustion, and direct exhaust gases out of the cylinder. When the engine system is in skip-fire CDA mode, the intake valve may118remain closed thereby preventing air from entering the cylinder and being combined with fuel to cause combustion. In some embodiments, the exhaust valve120remains closed, as no exhaust gases are present in the cylinder that must be allowed to exit the cylinder. In other embodiments, during skip-fire CDA mode, the intake and exhaust valves are allowed to selectively open and close akin to operation during non-skip-fire CDA mode, but combustion does not occur due to no fuel being injected (compression ignition engines) or a spark being commanded (spark-initiated engines). In these embodiments, air circulates through the deactivated cylinders but does not combust. The fuel injector assembly102is coupled to the cylinder head104and is in fluid communication with the cylinder. The fuel injector assembly102is configured to deliver, transmit, inject, or otherwise provide fuel to the cylinder for combustion. The fuel injector assembly102may include, but is not limited to, an injector body106, an injector needle108, an injector nozzle retainer110, an injector combustion seal member112, an injector nozzle114, and an injector nozzle tip116. The injector body106is an outer housing of the fuel injector assembly102and is configured to house and secure the components of the fuel injector assembly102. The injector needle108is sized and configured to fit within the injector nozzle114and is sized to occlude the injector nozzle tip116when located at the bottom of the injector nozzle114. The injector needle108is operable to move based on electrical signals received by the fuel injector assembly102. In some embodiments, when fuel is not being injected in to the cylinder associated with the fuel injector assembly102, the injector needle108is in contact with the injector nozzle tip116such that the injector needle108occludes the injector nozzle tip116to prevent fuel from exiting the injector nozzle tip116. In some embodiments, when fuel is injected into the cylinder associated with the fuel injector assembly102, an electrical signal may activate various components within the fuel injector assembly102to raise the injector needle108, thereby allowing fuel to flow through the injector nozzle tip116. To lower the injector needle108, the electrical signal may be stopped. The injector nozzle retainer110is configured to secure, hold, or otherwise retain the injector nozzle114to the injector body106. The injector nozzle retainer110is further configured to contact the injector combustion seal member112to create a seal between the fuel injector assembly102and the cylinder head104. The injector combustion seal member112may be any type of sealing component configured to maintain a seal between the injector nozzle retainer110and the cylinder head104. Examples of the injector combustion seal member112include, but are not limited to, o-rings, washer seals, etc. The injector nozzle114is configured to receive the injector needle108and to provide a fuel passage through which fuel flows when fuel is being injected into a cylinder. The injector nozzle114extends into the cylinder and terminates at the injector nozzle tip116, which includes an injector passage in fluid communication with the fuel passage. The injector passage is also in fluid communication with the cylinder so fuel flowing through the fuel passage reaches the injector passage, and eventually flows into the cylinder through the injector passage in preparation for a combustion event. The controller122is coupled to the system100and the fuel injector assembly102and is configured to at least partly control the operation of the fuel injector assembly102. The controller122is further described with reference toFIG.2. Referring now toFIG.2, a schematic diagram of the controller122ofFIG.1is shown, according to an exemplary embodiment. The controller122is structured to receive inputs (e.g., signals, information, data, etc.) from the engine system. Thus, the controller122is structured to control, at least partly, the fuel injector assembly102(and, at least partly, components of the engine system). As the components ofFIG.2can be embodied in a vehicle, the controller122may be structured as one or more electronic control units (ECU). The controller may be separate from or included with at least one of a transmission control unit, an exhaust aftertreatment control unit, a powertrain control module, and engine control module, etc. As shown, the controller122includes a processing circuit210having a processor212and a memory device214, a control system230having an input circuit232, a control logic circuit234, an output circuit236, and a communications interface250. In one configuration, the input circuit232, the control logic circuit234, and the output circuit236are embodied as machine or computer-readable media that is executable by a processor, such as processor212and stored in a memory device, such as memory device214. As described herein and amongst other uses, the machine-readable media facilitates performance of certain operations to enable reception and transmission of data. For example, the machine-readable media may provide an instruction (e.g., command, etc.) to, e.g., acquire data. In this regard, the machine-readable media may include programmable logic that defines the frequency of acquisition of the data (or, transmission of the data). The computer readable media may include code, which may be written in any programming language including, but not limited to, Java or the like and any conventional procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program code may be executed on one processor or multiple remote processors. In the latter scenario, the remote processors may be connected to each other through any type of network (e.g., CAN bus, etc.). In another configuration, the input circuit232, the control logic circuit234, and the output circuit236are embodied as hardware units, such as electronic control units. As such, the input circuit232, the control logic circuit234, and the output circuit236may be embodied as one or more circuitry components including, but not limited to, processing circuitry, network interfaces, peripheral devices, input devices, output devices, sensors, etc. In some embodiments, the input circuit232, the control logic circuit234, and the output circuit236may take the form of one or more analog circuits, electronic circuits (e.g., integrated circuits (IC), discrete circuits, system on a chip (SOCs) circuits, microcontrollers, etc.), telecommunication circuits, hybrid circuits, and any other type of “circuit.” In this regard, the input circuit232, the control logic circuit234, and the output circuit236may include any type of component for accomplishing or facilitating achievement of the operations described herein. For example, a circuit as described herein may include one or more transistors, logic gates (e.g., NAND, AND, NOR, OR, XOR, NOT, XNOR, etc.), resistors, multiplexers, registers, capacitors, inductors, diodes, wiring, and so on). The input circuit232, the control logic circuit234, and the output circuit236may also include programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like. The input circuit232, the control logic circuit234, and the output circuit236may include one or more memory devices for storing instructions that are executable by the processor(s) of the input circuit232, the control logic circuit234, and the output circuit236. The one or more memory devices and processor(s) may have the same definition as provided below with respect to the memory device214and processor212. In some hardware unit configurations, the input circuit232, the control logic circuit234, and the output circuit236may be geographically dispersed throughout separate locations in, for example, a vehicle. Alternatively and as shown, the input circuit232, the control logic circuit234, and the output circuit236may be embodied in or within a single unit/housing, which is shown as the controller122. In the example shown, the controller122includes the processing circuit210having the processor212and the memory device214. The processing circuit210may be structured or configured to execute or implement the instructions, commands, and/or control processes described herein with respect to the input circuit232, the control logic circuit234, and the output circuit236. The depicted configuration represents the input circuit232, the control logic circuit234, and the output circuit236as machine or computer-readable media that may be stored by the memory device. However, as mentioned above, this illustration is not meant to be limiting as the present disclosure contemplates other embodiments where the input circuit232, the control logic circuit234, and the output circuit236, or at least one circuit of the input circuit232, the control logic circuit234, and the output circuit236, is configured as a hardware unit. All such combinations and variations are intended to fall within the scope of the present disclosure. The processor212may be a single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. Accordingly, the processor212may be a microprocessor, a different type of processor, or state machine. The processor212also may be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some embodiments, the processor212may two or more processors that may be shared by multiple circuits (e.g., the input circuit232, the control logic circuit234, and the output circuit236may comprise or otherwise share the same processor which, in some example embodiments, may execute instructions stored, or otherwise accessed, via different areas of memory). Alternatively or additionally, the processors may be structured to perform or otherwise execute certain operations independent of the other co-processors. In other example embodiments, the processors may be coupled via a bus to enable independent, parallel, pipelined, or multi-threaded instruction execution. All such variations are intended to fall within the scope of the present disclosure. The memory device214(e.g., memory, memory unit, storage device) may include one or more devices (e.g., RAM, ROM, Flash memory, hard disk storage) for storing data and/or computer code for completing or facilitating the various processes, layers and modules described in the present disclosure. The memory device214may be coupled to the processor212to provide computer code or instructions to the processor212for executing at least some of the processes described herein. Moreover, the memory device214may be or include tangible, non-transient volatile memory or non-volatile memory. Accordingly, the memory device214may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described herein. The input circuit232is structured to receive information from one or more fuel injector assemblies (e.g., the fuel injector assembly102) and/or one or more sensors coupled to the one or more fuel injector assemblies via the communications interface250. The sensors may include one or more of a temperature sensor (e.g., to determine a temperature of an injector nozzle tip such as the injector nozzle tip116), a flow sensor (e.g., to determine a flow rate of fuel flowing through a fuel injector assembly such as the fuel injector assembly102), an optical sensor (e.g., to determine an amount of fuel or lubricant within the fuel injector assembly102), or any other type of sensor that can provide information related to the operation of a fuel injector assembly. In some arrangements, the information generated by the sensors is sent to the control logic circuit234wirelessly (e.g., the sensors include a wireless transmitter to transmit information and the control logic circuit234includes a wireless receiver to receive the information). The information generated by the sensors can also be sent to the control logic circuit234via a wired connection. The input circuit232may modify or format the sensor information (e.g., via analog/digital converter) so that the sensor information can be readily used by the control logic circuit234. In some embodiments, the sensor information may include the temperature of the injector nozzle tip116during skip-fire CDA mode. In some embodiments, the sensor information may include an amount or temperature of static fuel in the injector nozzle114during skip-fire CDA mode. In some embodiments, the sensor information may include an amount of lubricant on or proximate to the injector needle108and/or a temperature of the lubricant on or proximate to the injector needle108during skip-fire CDA mode or at another time (e.g., immediately before activation of skip-fire CDA mode). The control logic circuit234is structured to receive information regarding the fuel injector assembly102from the input circuit232and to determine skip-fire CDA operation strategy based on the information. For example, the control logic circuit234can determine whether the vehicle should operate in skip-fire CDA mode, which cylinders will be fired and which cylinders will be skipped when in skip-fire CDA mode, the number of cycles during which the skip-fire CDA mode will operate, etc. As used herein, “control parameters” refer to values or information determined within the control logic circuit234by the embedded control logic, model, algorithm, or other control scheme. The control parameters may include values or information that represents a status or a state of a vehicle system, a predictive state information, or any other values or information used by the control logic circuit234to determine what the controller122should do or what the outputs should be. For a skip-fire CDA system, a complex control scheme is needed to balance requirements to meet a requested torque demand at an optimum fuel efficiency, while assuring reliable operation of inactive cylinders after those cylinders are activated. In order to control the technology needed to meet these requirements, “control parameters” are needed to understand the current state of the components and how to adjust the actuators. On a typical modern diesel engine, there are on the order of thirty sensors and fifteen actuators. This includes items like: air handling components, including variable geometry turbochargers, EGR valves, throttles, variable valve actuators, etc.; combustion, including multiple fuel injection events varying in quantity and timing, fuel pressure, etc.; and aftertreatment, including catalyst bed temperatures, stored constituents (like ammonia or particulates), progress towards filling or regeneration of the catalyst, special cleaning events, etc. In some embodiments, the control logic circuit234includes algorithms or traditional control logic (e.g., PIDs, etc.). In some embodiments, the control logic circuit234includes modelling architecture for component integration or other model based logic (e.g., physical modelling systems that utilize lookup tables). In some embodiments, the control logic circuit234utilizes one or more lookup tables stored on the memory device214for determination of the control parameters. In some embodiments, the control logic circuit234may include artificial intelligence or machine learning circuits, or fuzzy logic circuits, as desired. In one embodiment, the control logic circuit234may receive a request related to a skip-fire CDA mode, and determine a control parameter in the form of activating or deactivating one or more cylinders. In another embodiment, the control logic circuit234may receive a request related to a skip-fire CDA mode, and determine a control parameter in the form of one or more thresholds related to characteristics of the fuel injector assembly102. The output circuit236is structured to receive the control parameters from the control logic circuit234and provide outputs in the form of actuation information (e.g., the “output”) to the system100via the communications interface250. In some embodiments, the output circuit236receives a threshold tip temperature for the injector nozzle tip116from the control logic circuit234and outputs a signal to the system100to activate if the actual tip temperature of the injector nozzle tip116is greater than the threshold tip temperature. In some embodiments, the output circuit236receives a threshold fuel temperature for the static fuel in the injector nozzle114from the control logic circuit234and outputs a signal to the system100to activate if the actual fuel temperature of the static fuel in the injector nozzle114is greater than the threshold fuel temperature. In some embodiments, the output circuit236receives a threshold amount of static fuel in the fuel injector assembly102from the control logic circuit234and outputs a signal to the system100to activate if the actual amount of static fuel in the fuel injector assembly102is greater than the threshold amount. In some embodiments, the output circuit236receives a threshold lubrication amount for the injector needle108from the control logic circuit234and outputs a signal to the system100to activate if the actual lubrication amount of the injector needle108is less than the threshold lubrication amount. According to various embodiments, the actual temperature of the injector nozzle tip116may be determined by direct measurement or by proxy based on various operating parameters of the system100. To measure the actual temperature of the injector nozzle tip116via direct measurement, one or more temperature sensors (e.g., thermocouples, etc.) coupled to the controller122may be placed in, on, or near the injector nozzle tip116. To measure the temperature of the injector nozzle tip116by proxy (e.g., determined or predicted), the temperature of the injector nozzle tip116may be estimated by the controller122based on operating parameters such as the number of continuous deactivation cycles (e.g., the number of consecutive cycles during which a particular cylinder is deactivated), the engine speed, the engine torque, and any other parameters associated with the engine system that may indicate the temperature of the injector nozzle tip116. When the cylinder associated with the injector nozzle tip116is deactivated during skip-fire CDA mode for an extended period of time (e.g., more than a predefined threshold value, such as a time value (e.g., 30 minutes) or a usage value (e.g., 30 engine cycles)), the temperature of the cylinder may continue to steadily increase based on the work being done inside the deactivated cylinder. As the temperature of the cylinder increases, the temperature of the injector nozzle tip116may also increase beyond a temperature threshold value (e.g., a temperature greater than approximately three hundred degrees Celsius), which may cause/result in coking of the injector nozzle tip116. Activating the cylinder when the temperature of the injector nozzle tip116is greater than a threshold tip temperature (e.g., approximately three hundred degrees Celsius) may reduce the temperature of the injector nozzle tip116, thereby preventing coking of the injector nozzle tip116. According to various embodiments, the actual temperature of the static fuel in the fuel injector assembly102and/or the amount of static fuel in the fuel injector assembly102may be determined by direct measurement or by proxy based on various operating parameters of the system100. To measure the actual temperature of the static fuel via direct measurement, one or more sensors (e.g., thermocouples, etc.) coupled to the controller122may be placed in, on, or near the injector nozzle114. To measure the temperature of the static fuel by proxy (e.g., determined or predicted), the temperature of the static fuel may be estimated by the controller122based on operating parameters such as the number of continuous deactivation cycles (e.g., the number of consecutive cycles during which a particular cylinder is deactivated), the engine speed, the engine torque, and any other parameters associated with the engine system that may indicate the temperature of the static fuel in the fuel injector assembly102. To measure the amount of static fuel in the fuel injector assembly102via direct measurement, one or more sensors (e.g., force sensors, pressure sensors, optical sensors, etc.) coupled to the controller122may be placed in, on, or near the injector nozzle114. To measure the amount of static fuel by proxy (e.g., determined or predicted), the amount of static fuel may be estimated by the controller122based on operating parameters such as the number of continuous deactivation cycles (e.g., a known amount of fuel may enter the injector nozzle114during each deactivation cycle, causing the amount of static fuel to increase over time), the engine speed, the engine torque, and any other parameters associated with the engine system that may indicate the amount of static fuel in the fuel injector assembly102. When the cylinder associated with the fuel injector assembly102is deactivated during skip-fire CDA mode, the amount of static fuel in the fuel injector assembly102may continue to increase. For example, a known amount of fuel may enter the injector nozzle114during each deactivation cycle. In some instances, fuel may continue to enter the injector nozzle114during each deactivation cycle if the system100is not adequately sealed, causing an unknown amount of fuel to enter the injector nozzle114during each deactivation cycle. Furthermore, the temperature of the static fuel in the fuel injector assembly102may continue to increase based on the work being done in the deactivated cylinder. Increasing the amount of static fuel and/or the temperature of the static fuel may cause coking of the injector nozzle tip116. Activating the cylinder when the temperature of the static fuel is above a threshold temperature may reduce the temperature of the static fuel, thereby preventing coking of the injector nozzle tip116. Furthermore, activating the cylinder when the amount of static fuel is greater than a threshold amount may reduce and/or expel the static fuel, thereby preventing coking of the injector nozzle tip116. According to various embodiments, the amount of lubricant on the injector needle108may be determined by direct measurement or by proxy based on various operating parameters of the system100. To measure the actual amount of lubricant on the injector needle108via direct measurement, one or more sensors (e.g., optical sensors, flow sensors, etc.) coupled to the controller122may be placed on or near the injector needle108to detect the amount of lubrication present on the injector needle108. To measure the amount of lubricant on the injector needle108by proxy (e.g., determined or predicted), the amount of lubricant may be estimated by the controller122based on operating parameters such as the number of continuous deactivation cycles (e.g., a certain amount of lubricant may be consumed during each deactivation cycle, causing the lubrication level to decrease over time), the engine speed, the engine torque, and any other parameters associated with the engine system that may indicate the amount of lubrication on or near the injector needle108. When the cylinder associated with the injector needle108is deactivated during skip-fire CDA mode, the lubrication level of the injector needle108may change. Because the injector needle108moves up and down within the injector nozzle114when the cylinder is active, sufficient lubrication must be present on one or both of the injector needle108and the injector nozzle114to prevent sticking. Sufficient lubrication allows the injector needle108to move up and down smoothly to provide for consistent fuel injection into the cylinder. In some embodiments, lubricant may be provided to the injector needle108and/or the injector nozzle114when the cylinder is active. When the cylinder is deactivated during skip-fire CDA mode, the heat associated with operation of the engine system may cause some of the lubricant to evaporate or evacuate from the assembly thereby leaving less lubricant on the injector needle108than desirable for operation of an active cylinder. In addition, lubricant in an inactive cylinder may flow away from the desired surfaces (e.g., the contact points between the injector needle108and the injector nozzle114) such that the amount of lubricant in the desired location is less than the amount necessary for operation of an active cylinder. Having less lubricant than needed for operation of an active cylinder may cause the injector needle108to stick within the injector nozzle114during operation of an active cylinder, which would prevent fuel from flowing properly into the cylinder and negatively affect the efficiency of the engine system. Furthermore, the heat associated with operation of the engine system when the cylinder is deactivated during skip-fire CDA mode may cause lubricant additives in the fuel (e.g., diesel fuel) to break down (e.g., evaporate, change chemical structure, etc.) over time. Such a breakdown of lubricant additives can cause the properties of the lubricant to change such that the lubricant with broken down additives provides less lubrication than the original lubricant. Activating the cylinder when the amount of lubricant is lower than a threshold level for efficient operation of the engine system, or before the lubricant additives have broken down, may prevent the injector needle108from sticking in the injector nozzle114. FIG.3is a flow diagram of a method300to control skip-fire CDA operation of a cylinder, according to an exemplary embodiment. The method300may be implemented, at least in part, by the controller122such that reference is made to the controller122to aid in explanation of the method300. At302, the engine is operated in skip-fire CDA mode. For example, the vehicle operated by the engine may not require all cylinders to be active for efficient operation (e.g., the vehicle may be traveling on a flat highway at a constant speed). The controller122may determine that one or more of the cylinders of the engine can be deactivated to provide for more efficient operation. At304, a determination is made as to whether the temperature of the injector nozzle tip116is greater than a threshold temperature. For example, as the cylinder associated with the injector nozzle tip116remains inactive for consecutive cycles such as engine cycles, the temperature of the injector nozzle tip116may increase based on the work being done by the inactive cylinder. The controller122compares the actual temperature of the injector nozzle tip116to a threshold tip temperature (e.g., approximately three hundred degrees Celsius). If the actual temperature of the injector nozzle tip116is lower than the threshold tip temperature, the controller122may maintain the cylinder in an inactive state in skip-fire CDA mode at302. If the actual temperature of the injector nozzle tip116is greater than the threshold tip temperature, at310the controller122may activate the cylinder associated with the injector nozzle tip116to exit skip-fire CDA mode for that cylinder. Activating the cylinder associated with the injector nozzle tip116may reduce the actual temperature of the injector nozzle tip116below the threshold tip temperature, thereby reducing the likelihood of coking of the injector nozzle tip116when in skip-fire CDA mode. At306, a determination is made as to whether the amount of static fuel in the fuel injector assembly102and/or static fuel temperature is greater than a threshold value. For example, as the cylinder associated with the injector nozzle114remains inactive for consecutive cycles, the temperature of the static fuel within the injector nozzle114may increase. Furthermore, the amount of static fuel within the injector nozzle114may increase. The controller122may compare the actual temperature of the static fuel within the injector nozzle114to a threshold fuel temperature value (e.g., approximately three hundred degrees Celsius). If the actual temperature of the static fuel is lower than the threshold fuel temperature, the controller122may maintain the cylinder in an inactive state in skip-fire CDA mode at302. If the actual temperature of the static fuel is greater than the threshold fuel temperature, at310the controller122may activate the cylinder associated with the injector nozzle114to exit skip-fire CDA mode for that cylinder. Furthermore, the controller122may compare the amount (e.g., volume) of static fuel within the injector nozzle114to a threshold fuel amount. If the amount of static fuel within the injector nozzle114is less than the threshold fuel amount, the controller122may maintain the cylinder in an inactive state in skip-fire CDA mode at302. If the amount of static fuel within the injector nozzle114is greater than the threshold fuel amount, at310the controller122may activate the cylinder associated with the injector nozzle114to exit skip-fire mode for that cylinder. Activating the cylinder associated with the injector nozzle114may reduce the amount and/or temperature of the static fuel within the injector nozzle114below the threshold fuel amount and/or the threshold temperature, thereby reducing the likelihood of coking of the injector nozzle tip116when in skip-fire CDA mode. At308, a determination is made as to whether the amount of lubricant on the injector needle108is lower than a threshold value. For example, as the cylinder associated with the injector needle108remains inactive for consecutive cycles, the amount of lubricant on the injector needle108may decrease. The controller122may compare the amount of lubricant on the injector needle108to a threshold lubricant amount. If the actual amount of lubricant on the injector needle108is greater than the threshold lubricant amount, the controller122may maintain the cylinder in an inactive state in skip-fire CDA mode at302. If the actual amount of lubricant on the injector needle108is less than the threshold lubricant amount, at310the controller122may activate the cylinder associated with the injector needle108to exit skip-fire CDA mode for that cylinder. Activating the cylinder associated with the injector needle108when the amount of lubricant drops below the threshold lubricant amount may increase the amount of lubricant on the injector needle108, thereby reducing the likelihood of suboptimal engine operation due to sticking of the injector needle108. In some situations, direct sensing and/or measurement of operating parameters of or relating to a fuel injector may be inapplicable (e.g., if no sensors are in communication with the fuel injector assembly102). Accordingly, one or more of the injector nozzle tip temperature, static fuel amount and/or temperature, and injector lubrication level may be estimated (or in some embodiments, predicted) based on other parameters associated with operation of a vehicle and components thereof instead of measuring or sensing the parameter values directly. For example, the control logic circuit234may include a lookup table that provides correlations between one or more other parameters (e.g., engine torque, engine speed, intake manifold pressure and temperature, etc. and combinations thereof) and one or more of the injector nozzle tip temperature, static fuel amount and/or temperature, and injector lubrication level of the fuel injector assembly102. The correlations may be based on experimental data, in some instances. The correlations may also be based on mathematical relationships between operating parameters. Thus, in some embodiments, the use of sensed values may be replaced herein with estimated or predicted values using one or more processes, algorithms, etc. The other parameters may include, for example, parameters such as duration of a skip-fire operation, temperature of ambient air, and a number of skipped cycles such as injector cycles. In situations where the duration of a skip-fire operation is used as an estimate, a longer duration of skip-fire operation may be associated with higher nozzle tip and static fuel temperatures, larger amounts of static fuel, and lower lubrication levels than a shorter duration skip-fire operation. Accordingly, as a duration of a skip-fire operation increases, the likelihood of the control logic circuit234modifying the skip-fire operation to manage one or more of the injector nozzle tip temperature, static fuel amount and/or temperature, and injector lubrication level also increases. In situations where the temperature of the ambient air is used as an estimate, a higher ambient air temperature may be associated with higher nozzle tip and static fuel temperatures, larger amounts of static fuel, and lower lubrication levels than a lower ambient air temperature. Accordingly, as ambient air temperature increases, the likelihood of the control logic circuit234modifying the skip-fire operation to manage one or more of the injector nozzle tip temperature, static fuel amount and/or temperature, and injector lubrication level also increases. In situations where the number of skipped cycles such as injector cycles is used as an estimate, a higher number of skipped injector cycles may be associated with higher nozzle tip and static fuel temperatures, larger amounts of static fuel, and lower lubrication levels than a lower number of cycles. Accordingly, as the number of skipped injector cycles increases, the likelihood of the control logic circuit234modifying the skip-fire operation to manage one or more of the injector nozzle tip temperature, static fuel amount and/or temperature, and injector lubrication level also increases. For example, the lookup table may include a threshold number of skipped (e.g., deactivated) injector cycles (e.g., instances when the injector would have injected fuel but for the cylinder being deactivated). The control logic circuit234may reactivate one or more deactivated cylinders in response to the preset threshold number of deactivated injector cycles being reached or exceeded. Though specific examples of other parameters are described as being used to estimate one or more of the injector nozzle tip temperature, static fuel amount and/or temperature, and injector lubrication level, one of ordinary skill would understand that additional parameters may be used for the same purpose. In addition, estimation of one or more of the injector nozzle tip temperature, static fuel amount and/or temperature, and injector lubrication level can be accomplished using a single parameter or a combination of multiple parameters. For the purpose of this disclosure, the term “coupled” means the joining or linking of two members directly or indirectly to one another. Such joining may be stationary or moveable in nature. For example, a propeller shaft of an engine “coupled” to a transmission represents a moveable coupling. Such joining may be achieved with the two members or the two members and any additional intermediate members. For example, circuit A communicably “coupled” to circuit B may signify that circuit A communicates directly with circuit B (i.e., no intermediary) or communicates indirectly with circuit B (e.g., through one or more intermediaries). While various circuits with particular functionality are shown inFIG.2it should be understood that the controller122may include any number of circuits for completing the functions described herein. For example, the activities and functionalities of the circuits232-236may be combined in multiple circuits or as a single circuit. Additional circuits with additional functionality may also be included. Further, the controller122may further control other activity beyond the scope of the present disclosure. As mentioned above and in one configuration, the “circuits” may be implemented in machine-readable medium for execution by various types of processors, such as the processor212ofFIG.2. An identified circuit of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions, which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified circuit need not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the circuit and achieve the stated purpose for the circuit. Indeed, a circuit of computer readable program code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within circuits, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network. While the term “processor” is briefly defined above, the term “processor” and “processing circuit” are meant to be broadly interpreted. In this regard and as mentioned above, the “processor” may be implemented as one or more processors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), digital signal processors (DSPs), or other suitable electronic data processing components structured to execute instructions provided by memory. The one or more processors may take the form of a single core processor, multi-core processor (e.g., a dual core processor, triple core processor, quad core processor), microprocessor, etc. In some embodiments, the one or more processors may be external to the apparatus, for example the one or more processors may be a remote processor (e.g., a cloud based processor). Alternatively or additionally, the one or more processors may be internal and/or local to the apparatus. In this regard, a given circuit or components thereof may be disposed locally (e.g., as part of a local server, a local computing system) or remotely (e.g., as part of a remote server such as a cloud based server). To that end, a “circuit” as described herein may include components that are distributed across one or more locations. Although the diagrams herein may show a specific order and composition of method steps, the order of these steps may differ from what is depicted. For example, two or more steps may be performed concurrently or with partial concurrence. Also, some method steps that are performed as discrete steps may be combined, steps being performed as a combined step may be separated into discrete steps, the sequence of certain processes may be reversed or otherwise varied, and the nature or number of discrete processes may be altered or varied. The order or sequence of any element or apparatus may be varied or substituted according to alternative embodiments. All such modifications are intended to be included within the scope of the present disclosure as defined in the appended claims. Such variations will depend on the machine-readable media and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. The foregoing description of embodiments has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from this disclosure. The embodiments were chosen and described in order to explain the principles of the disclosure and its practical application to enable one skilled in the art to utilize the various embodiments and with various modifications as are suited to the particular use contemplated. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the embodiments without departing from the scope of the present disclosure as expressed in the appended claims. Accordingly, the present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the disclosure is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, Z, X and Y, X and Z, Y and Z, or X, Y, and Z (i.e., any combination of X, Y, and Z). Thus, such conjunctive language is not generally intended to imply that certain embodiments require at least one of X, at least one of Y, and at least one of Z to each be present, unless otherwise indicated. | 50,877 |
11859568 | DETAILED DESCRIPTIONS OF ILLUSTRATED EMBODIMENTS The following examples are described to illustrate preferred embodiments for carrying out the invention in practice, as well as certain preferred alternative embodiments to the extent they seem particularly illuminating at the time of this writing. In the course of understanding these various descriptions of preferred and alternative embodiments, those of skill in the art will be able to gain a greater understanding of not only the invention but also some of the various ways to make and use the invention and embodiments thereof. Wording Conventions For purposes of these descriptions, a few wording simplifications should be understood as universal, except to the extent otherwise clarified in a particular context either in the specification or in any claims. For purposes of understanding descriptions that may be basic to the invention, the use of the term “or” should be presumed to mean “and/or” unless explicitly indicated to refer to alternatives only, or unless the alternatives are inherently mutually exclusive. When referencing values, the term “about” may be used to indicate an approximate value, generally one that includes a standard deviation of error for any particular embodiments that are disclosed or that are commonly used for determining or achieving such value. Reference to one element, often introduced with an article like “a” or “an”, may mean one or more, unless clearly indicated otherwise. Such “one or more” meanings are most especially intended when references are made in conjunction with open-ended words such as “having,” “comprising” or “including.” Likewise, “another” may mean at least a second or more. Other words or phrases may have defined meanings either here or in the accompanying background or summary descriptions, and those defined meanings should be presumed to apply unless the context suggests otherwise. These descriptions occasionally point out and provide perspective as to various possible alternatives to reinforce that the invention is not constrained to any particular embodiments, although described alternatives are still just select examples and are not meant to represent an exhaustive identification of possible alternatives that may be known at the time of this writing. The descriptions may occasionally even rank the level of preference for certain alternatives as “most” or “more” preferred, or the like, although such ranked perspectives should be given little importance unless the invention as ultimately claimed irrefutably requires as much. Indeed, in the context of the overall invention, neither the preferred embodiments nor any of the referenced alternatives should be viewed as limiting unless our ultimate patent claims irrefutably require corresponding limits without any possibility for further equivalents, recognizing that many of the particular elements of those ultimate patent claims may not be required for infringement under the U.S. Doctrine of Equivalents or other comparable legal principles. Having said that, even though the invention should be presumed to cover all possible equivalents to the claimed subject matter, it should nonetheless also be recognized that one or more particular claims may not cover all described alternatives, as would be indicated either by express disclaimer during prosecution or by limits required in order to preserve validity of the particular claims in light of the prior art. As of the date of writing, the structural and functional combinations characterized by these examples are thought to represent valid preferred modes of practicing the invention. However, in light of the present disclosure, those of skill in the art should be able to fill-in, correct or otherwise understand any gaps, misstatements or simplifications in these descriptions. For descriptive reference, we categorize supply flowrate setpoint accuracy as being “generally accurate” if it is consistently within 5% of the demanded flowrate across its entire operating range. When consistently within 3% of the demanded flowrate across the entire range, setpoint accuracy can be categorized as “highly accurate.” At the extreme, when setpoint accuracy is consistently within about 1% of the demanded flowrate across the entire operating range, it can be classified as “extremely accurate.” It is also notable that, while many embodiments may be used for mass flow control of either air or fuel, or combinations of air and fuel, these descriptions will commonly refer to control of a “supply flow”, which should generally be understood to refer to control of any such supply flow, whether it be air, fuel, or a combination. It will be understood, nonetheless, that a throttle according to these descriptions that is intended strictly for controlling the fuel supply flow will be plumbed at a different location than one that is plumbed for just controlling air. Likewise, a throttle according to these descriptions that is deployed for controlling mass flow of air without fuel will be plumbed at a different location than one that is plumbed for controlling the mixture of fuel and air. We presently prefer to include one throttle for controlling just the gaseous fuel supply flow, to achieve highly accurate control of the mass flow of the fuel (sometimes referred to as mass-flow-gas, or “MFG”), together with another throttle further downstream for controlling the supply flow after air has been mixed with the supply flow of fuel (which is sometimes referred to as mass-flow-air, or “MFA”, irrespective of the inclusion of the fuel in the same flow). Nonetheless, complete and highly accurate mass flow control can also be achieved by combining an MFG throttle together with an MFA throttle that is plumbed in the air supply upstream of the fuel-air mixer. Moreover, generally accurate overall control might also be attainable by just controlling the mass flow of the fuel, without actively controlling the mass flow of the air if other reliable data is used to calculate that mass flow of the air, such as through use of oxygen sensors in combination with pressure, temperature and the like. With respect to any valve, throttle or actuator, “fast-acting” is a term that is generally understood by those of skill in the art, and the term should be presumed to generally mean that it is designed to act or respond considerably faster or quicker than most throttles, valves or actuators. More limited definition may be applied to the phrase to the extent expressly disclaimed during prosecution or to the extent necessary for preserving validity of particular claims in light of the prior art. Despite the presumed broader meaning, fast-acting actuators referenced in these descriptions are preferably operable to move the actuated throttle element through most of its entire operable range of motion (preferably from 20% to 80% of that operable range), if not all of that operable range, in fifty milliseconds or less, although many other types of actuators are still likely to be suitable as alternatives, especially to the extent particular claim elements are not expressly disclaimed to require particular fast-acting characteristics. The term “large engine throttle”10is used herein to describe the mass-flow throttle of numerous preferred embodiments and it refers to the throttle and throttle control system rather than merely the throttle body20or the butterfly valve (or throttle blade)210therein. Despite the “large engine” descriptor for throttle10, the reader should understand that various aspects of such large engine throttle may be beneficial for smaller engines as well, such that the reference to “large engine” should not be considered as limiting unless estoppel, validity in view of the prior art, or other legal principles clearly require an interpretation that is limited to large engines. The simpler term “throttle”20is used herein interchangeably with the term “throttle body assembly”20. With respect to fuels, the term “fluid” is used herein to mean either a liquid or a gas, although liquid fuel embodiments are preferably adapted to vaporize the liquid phase of the fuel before the flow reaches the large engine throttle10. In the context of a supply flowrate control, a “continuous fluid passage” refers to a fluid passageway of any sort, whether defined through tubes, channels, chambers, baffles, manifolds or any other fluid passageway that is uninterrupted by fully closed valves, pistons, positive displacement pumps or the like during its normal operative mode of controlling the fuel flowrate, such that gaseous fluid is generally able to continually flow through a continuous fluid passage whenever a pressure gradient is present to cause such flow. It should be recognized, though, that a continuous fluid passage in this context can be regulated to zero flowrate by reducing the effective area of an opening to zero, while the passage would still be considered as a continuous fluid passage in this context. In addition, absent clear disclaimer otherwise, equivalent structures can be fully closed when not operating to control the flowrate, and equivalent structures may also have parallel or alternate passageways where one or more may be interrupted without discontinuing the overall flow. Exploded and Unexploded Views of Large Engine Throttle10 Turning toFIGS.1A and1B, there are shown perspective views of the preferred large engine throttle10. As shown therein, large engine throttle10includes an inlet adapter30and an outlet adapter40. Inlet adapter30, in part, defines supply inlet390, which is configured to allow supply flow into large engine throttle10. Outlet adapter40, in part, defines supply outlet170(shown inFIGS.2B and10), which is configured to allow supply flow out of large engine throttle10. Machine screws31-34are paired with machine nuts31a-34afor securing inlet adapter30to housing assembly20(shown in more detail inFIGS.2A-4). Similarly, machine screws41-44are paired with machine nuts41a-44afor securing outlet adapter40to housing assembly20. Detailed descriptions of assemblies and components of the preferred embodiment are provided in ensuing paragraphs. With reference toFIG.2A, there is shown a two-dimensional view of the large engine throttle10. A coolant port220can be seen in the front of housing assembly20(shown in dashed-line box) and another coolant port221(not shown) is located on the opposite side. Especially when throttle10is used as an air-fuel (MFA) throttle, hot gasses may flow through throttle10. To cope with the temperature of such hot gasses, and particularly to guard against thermal damage to the control circuitry associated with PCB900or to the motor700, a heat dissipator (not numbered) is located within the unitary block assembly99between main throttle body20and motor700as well as PCB900. The heat dissipater preferably is in the form of an aluminum component enclosing one or more flow-through passageways with relatively large surface areas for enabling liquid coolant to circulate therethrough and thereby cool the aluminum component. As will be understood by those of skill in the art, heat dissipators are commonly used on turbocharged applications like the large engine throttle10. The coolant ports220and221enable coolant to enter and flow around the large engine throttle10to keep the brushless motor700(shown inFIG.7) and main PCB900(shown inFIG.9) from overheating. With reference toFIG.2B, there is shown a cross-section, indicated by line B-B, of the embodiment illustrated inFIG.2Arotated clockwise 90 degrees. The throttle shaft710(sometimes referred to as an actuator “drive shaft”) controls movement of the throttle blade210, with minimal opportunity for slop or other errors. The upstream pressure P1(upstream of throttle blade210) is measured at port230by pressure sensor951on PCB900, as the stovepipe of sensor951is connected in open fluid communication with port230, through an open passage (not shown) that runs through the unitary block assembly and a tube between port230and the stovepipe of sensor951. Likewise, the downstream pressure P2(downstream of throttle blade210) is measured at port240by pressure sensor952on PCB900, as the stovepipe of sensor952is connected in open fluid communication with port240, through an open passage (not shown) that runs through the unitary block assembly and a tube between port240and the stovepipe of sensor952. Each of ports230and240have fluid passage segments in close proximity to the ports that are oriented perpendicular to the flowline of the throttle fluid passage of throttle10, to minimize stagnation or suction pressures due to their orientation relative to flow. However, the next adjacent segments of each are oriented to slope slightly upwardly relative to gravity in order to minimize the risk of clogging. The temperature of the fluid is measured at port250using a thermistor600(shown inFIG.6). Machine screws201-204unite throttle body assembly20with intermediate housing assembly80. With reference toFIG.3, dashed-line boxes are used to depict some of various assemblies of and within an embodiment of the unitary block assembly99of throttle10. While some (but not all) embodiments of the throttle10employ a unitary block for each throttle10, assemblies that rigidly unite to form the unitary block assembly99include the walls22of central throttle body20, the spring return cover550of spring return assembly50at the end toward the right inFIG.3, control circuitry cover901at the other end toward the left inFIG.3, with the intermediate housing800of motor enclosure80positioned between throttle body20and the PCB space. In addition, as will be understood, numerous screws are used to rigidly unite the sub-blocks of the embodiment ofFIG.3together, preferably with inset seals to ensure a sealed union between each of the various subblocks. Two additional subblocks—namely the inlet extension and the flow outlet extension are also united to the unitary block assembly99ofFIG.3. Analogously, the unitary block assembly99′ of the embodiment shown ifFIG.3Ais also very similar to assembly99ofFIG.3. More particularly, the unitary block assembly is composed of various sub-blocks and covers that are preferably all of predominantly aluminum composition in the preferred embodiment. The resulting unitary block assembly of throttle10defines the inner and outer surfaces of throttle10. That unitary block assembly is illustrated as a billet type assembly of aluminum parts evident in the various views ofFIGS.1-4, although it should be understood that preferred embodiments may also be formed through larger castings having fewer sub-blocks in order to reduce costs for volume production. These assemblies are illustrated in greater detail in the figures that follow. InFIG.3there is shown an inlet adapter30above a throttle body assembly20(more particularly shown inFIG.4). Four screws31-34(three shown) unite the inlet adapter30to the throttle body assembly20with a circular seal35, to sealingly enable mass flow from upstream into the throttle body assembly20. Similarly, the outlet adapter40is united with throttle body assembly20using screws41-44with a circular seal45, to sealingly enable mass flow downstream from the throttle body assembly20. Although of secondary importance, it may be noted that the inlet adapter30and outlet adapter40are more beneficial when throttle10is being used as an MFG throttle, as opposed to when it is being used as an MFA throttle. Although each of the plurality of spaces defined by the unitary block assembly and that collectively contain the rotary shaft710—namely the PCB space, the motor space of intermediate housing800, the throttle body space, and the spring return assembly space of assembly50—are formed by sealed uniting of adjacent sub-blocks, leakage may still occur from one such space to the next due to the imperfect seals around a rotating shaft710. Accordingly, to protect the control circuitry of PCB900from the corrosive effects of gaseous fuel supplies, electronic components of PCB900are coated with a coating that is protective of such electronic components against the otherwise corrosive characteristics of gaseous fuels. To the right of throttle body20is a spring assembly50(shown in detail inFIG.5). The spring assembly50operates as a torsion type spring that winds up while the block assembly10is powered on. When the block assembly10is powered off, the spring assembly50winds down and returns to a closed position or, more preferably, to a substantially closed position. To the left of throttle body20is a thermistor assembly60(shown in detail inFIG.6) that senses temperature. Also to the left of throttle body assembly20is a motor and throttle shaft assembly70(shown in detail inFIG.7) that controls the movement of the throttle (shown inFIG.4). An intermediate housing assembly80(shown in detail inFIG.8) unites the motor and throttle shaft assembly70and a printed circuit board (PCB) assembly90(shown in detail inFIG.9). As an alternative to the embodiments ofFIGS.3and5,FIGS.3A and5Ashow a comparable but alternative embodiment. However, due to the close similarities of throttle10′ as compared to throttle10, the parts in each ofFIGS.3A and5Aare numbered similarly to the comparable parts ofFIGS.3and5, with the main difference being the addition of a prime symbol (“′”) for the components of the embodiment ofFIGS.3A and5A. Particularly, with reference toFIG.3A, most all the subassemblies of the throttle10′ are practically similar to those of throttle10ofFIG.3, with the most notable exception being the spring return assembly500′, which has components analogous but different from those of spring return assembly500. Nonetheless, details ofFIG.5Aare different enough from those similar details ofFIG.5that some description may be helpful. Particularly, component510′ ofFIG.5Ais a shaft seal. In this embodiment, seal retainer511′ and512′ are merged as one component. Part501′ is a bushing separator that supports spring500′, and screw531′ screws the assembly50′ to the end of the throttle shaft710. D-shaped cutout in the screw531′ tend to orient the spring assembly to the desired orientation on the shaft710. Bearing assembly513′ is a conventional bearing assembly much like bearing assembly513and element520′ is a bearing freeload spring. Part530′ is spring return for returning throttle blade210to a five-degrees-from-fully closed position. Each end of the spring500′ has projecting flare that engages mating notches and the like to drive the spring-biased return of throttle blade210, in a manner that is generally common for many spring-biased returns for automotive throttles. Throttle Body Assembly20 With reference toFIG.4, there is shown an isometric view of the throttle body assembly (also referred to as “gaseous supply throttle”)20. As previously discussed, a throttle body assembly20may be used for controlling fuel flow rates, air flow rates, or fuel-air mixture flow rates. The cylindrically shaped volume of space from the top to the bottom of throttle body assembly20is defined herein as the throttle chamber205. For fuel throttles, the throttle orifice200is preferably between 50 millimeters and 76 millimeters in diameter. For fuel-air throttles, the throttle orifice200is preferably between 60 millimeters and 120 millimeters in diameter. Note that, although throttle orifice200is a circular-faced orifice in a preferred embodiment, other shapes may be used in alternative embodiments such as a square-shaped orifice. Spring Assembly50 With reference toFIG.5, there is shown an exploded view of the spring assembly50. On the left side ofFIG.5is a throttle shaft seal510(with insert) that seals the throttle shaft710(shown inFIG.7). A throttle seal spacer511separates the throttle shaft seal510from a seal retainer washer512. A roller bearing513is located between the seal retainer washer512and a wave spring520. A spring guide bearing501prevents torsional spring500from contacting or rubbing against the body of throttle10. A larger spring guide bearing502separates the torsional spring500from a spring return flange530. A screw-like perpendicular pin531located in the center of flange530of the spring assembly50serves to transmit the neutrally-biasing force of spring500to the shaft710and, in turn, to throttle blade210. Screws551-554fasten the spring return cover550to the throttle body assembly20, and an O-ring540sealingly unites the assemblies. With reference to the alternative embodiment ofFIG.5A, there is shown another exploded view of a spring assembly50′, which is structured comparably and functions in a manner generally comparable to spring assembly50. Thermistor Assembly60 With reference toFIG.6, there is shown an exploded view of the thermistor assembly60. In one embodiment, the thermistor600has a temperature measurement range from −70° C. to 205° C. The thermistor assembly60has two O-ring gaskets603and604that function as sealants. Lead wires611and612are soldered to thermistor PCB610, extend (not shown) through the intermediate housing assembly80, and are also soldered to the main PCB900. An epoxy overmolding620is used to protect the thermistor600and thermistor PCB610. A thermistor tube630encloses the epoxy overmolding620, thermistor600, and thermistor PCB610. The thermistor tube630is united with the throttle body assembly20using a screw640. Motor and Throttle Shaft Assembly70 With reference toFIG.7, there is shown the motor and throttle shaft assembly70. A brushless motor700controls the movement of the throttle shaft710. On the right side ofFIG.7is a throttle shaft seal (with insert)711. A throttle seal spacer712separates the throttle shaft seal711from the throttle shaft710. Four screws701-704(three shown) unite the brushless motor700and the throttle shaft710with the throttle body assembly20. The throttle shaft710extends all the way through the brushless motor700and connects to a rotor arm720. There are two rotary bearing assemblies705and706within motor700such that, together with the rotary bearing assembly513(or513′ in the embodiment ofFIG.3A), three bearing assemblies support the rotatable movement of shaft710. A screw730integrally fastens the rotor arm720to an end of the throttle shaft710that protrudes into the PCB space from the left side (as viewed inFIG.7) of the brushless motor700. The rotor arm720has a permanent magnet740permanently attached to a radially outward portion of rotor arm720, such that arm720can be used in conjunction with a magnet740to indirectly measure the position of the throttle blade210in its range of rotatable motion. Intermediate Housing Assembly80 With reference toFIG.8, there is shown the intermediate housing assembly80. A large open space810is used for housing the brushless motor700. A smaller circular opening820at the bottom left is used for housing the controller-area-network (CAN) pin connector that protrudes from the main PCB900. One small opening830at the top of the assembly80houses a reverse flow check valve840, to protect sensors from over-pressurization. Another smaller opening850houses a forward flow check valve860to protect sensors from over-pressurization. An in-groove seal870shaped to fit the intermediate housing assembly80sealingly unites assembly80to the throttle body assembly20. Printed Circuit Board (PCB) Assembly90 With reference toFIG.9, there is shown the PCB assembly90, which sealingly contains PCB900. The PCB900is enclosed in a space (the “PCB space”) defined between a PCB housing cover901and intermediate housing800, which are united by screws915-920in a sealed manner. The sealed union between cover901and intermediate housing800is partially enabled by an in-groove elastic seal902positioned perimetrically around the PCB space in the interface between intermediate housing800and PCB housing cover901. Twelve screws903-914securely fasten the PCB900and pressure sensors950-952to the PCB housing901. Six screws915-920(three shown) and a PCB housing seal902sealingly unite the PCB assembly90with the intermediate housing assembly80(shown inFIG.8). Such sealed integration enables optimal control and helps minimize extraneous artifacts or other influences that might otherwise affect its operation. PCB900comprises a microcontroller930, which can be any commercially available microcontroller with a memory that is capable of receiving machine readable code, i.e., software. The microcontroller930provides the “brains” of the large engine throttle10. Microcontroller930receives throttle position signals from Hall Effect sensors940a-e, pressure signals from pressure sensors950-952, temperature signals from the thermistor600, and control signals from the ECM100. The microcontroller930uses an algorithm to calculate throttle position in order to achieve the instantaneously desired mass flow rates and then outputs pulse width modulated and H-bridge signals to motor80to cause motor700to properly control the position of throttle blade210, while also outputting measured data to the ECM. PCB900has five pairs of identical Hall Effect sensors940a-ewhich are part of a position sensor assembly for indirectly detecting the position of throttle blades210. With cross reference toFIG.10, these sensors are collectively named “Blade Position Sensor”940. As the throttle shaft710rotates, the rotor arm720which is an integral part of shaft710rotates within the PCB space and this causes the magnet740to move relative to the Hall Effect sensors940a-e, which are able to detect the resulting changes in the magnetic field. These sensors940a-evary their output voltage in response to magnetic field changes and these electrical signals are processed by the microcontroller930. The sensors940a-eare used for calibrating the location of the throttle blade210relative to the strength of the magnetic field given by the magnet740. Delta-P sensor950is a double sided pressure transducer that measures the differential pressure (“Delta-P”) between the upstream pressure port230and downstream pressure port240. Two pressure sensor gaskets950aand950bseal Delta-P sensor950. Upstream pressure sensor951measures the absolute upstream pressure (“P1”) and has pressure sensor gasket951a. Downstream pressure sensor952measures the absolute downstream pressure (“P2”) and has pressure sensor gasket952a. The Delta-P sensor950is significantly more accurate in measuring the differential pressure than the method of mathematically subtracting the difference between P1and P2. However, there are conditions when the throttle operates at pressures out of range of the Delta-P sensor950. When the Delta-P sensor950begins to peg (ie, approaches its maximum reliable limits), the microcontroller930will begin using pressure sensors951and952to calculate the differential pressure. Once the maximum pressure range is exceeded, the microcontroller930will stop using Delta-P sensor950and switch entirely to pressure sensors951and952in addition, PCB900will troubleshoot other instances whenever P1, P2and/or Delta-P do not conform to rationality checks, in such cases a false signal is sent to ECM100. Pressure sensors951and952are conventional pressure transducers, although non-conventional ones (or even sensors or the like for fluid conditions other than pressure) can be considered for use as alternatives for some of the same purposes. Pressure transducers951and952are preferably of the type that can be and are mounted to PCB900and have stiff tube connectors (sometimes called “stove pipes”) extending from their bases, through which the transducers access the pressure to be sensed. To neutralize some of the effects of pressure fluctuations—particularly downstream pressure fluctuations—the control algorithms of microcontroller930preferably use time-averaged pressure readings from the pressure sensors950-952rather than instantaneous pressure readings. More particularly, based on the number of cylinders and the current RPM of the engine, as received by microcontroller930from ECM100, microcontroller930continuously determines the stroke cycle time for the pistons of engine102 FIG.10—Block Diagram In the illustrative block diagram ofFIG.10, there are four main segments of supply flow depicted for preferred embodiments: (1) an upstream gaseous fuel supply350depicted on the left; (2) a large engine throttle10depicted within the dashed-line box in the middle; and (3) an engine102depicted in the smaller dashed-line box further to the right. The three segments350,10, and102are operatively connected to provide rotary shaft power for any number of large engine applications, with fuel supply350serving as the basic gaseous fuel supply for engine102, and with large engine throttle10serving to provide accurate control of the gaseous fuel flowrate from that fuel supply350to engine102, in accordance with various teachings of the present invention. Upstream Fuel Supply350 As illustrated inFIG.10, fuel supply350preferably includes a fuel tank360serving as the source for fluid fuel, together with a mechanical pressure regulator370and other conventional components such as a shut-off gate valve380. Valve380is preferably controlled by ECM100, although independent control may be utilized in alternative embodiments. The gaseous fuel supply350is equipped and adapted to deliver a gaseous fuel supply to supply inlet390at desired pressure levels. More preferably, the gaseous fuel supply350is a natural gas or vaporized propane fuel supply that delivers natural gas or propane stored in fuel tank360. Though not shown inFIG.10, fuel tank360may be equipped with vaporization subassemblies and controls to manage LNG (liquefied natural gas) or propane vaporization and resulting pressure within fuel tank360and the associated lines365,375and376. Such vaporization subassemblies and controls for LNG preferably prime tank360by pre-circulating some of the stored LNG through a heat exchange loop that increases the temperature of the pre-circulated LNG to the point of partial or complete vaporization, thereby creating a vapor phase with an adequate pressure head within tank360. Line365preferably also includes a second heat exchanger downstream of the fuel tank360, to further aid in complete vaporization of the LNG or propane once gaseous fuel is allowed to flow from fuel supply350to large engine throttle10. Downstream of the heat exchanger in line365, the gaseous fuel is directed sequentially through a mechanical pressure regulator370, a downstream fuel shut-off valve380, and a line quick-disconnect assembly (not shown) prior to entry into large engine throttle10. In this embodiment, initial fuel pressure is supplied by the tank360, although the initial pressure from tank360is preferably regulated by mechanical pressure regulator370before reaching supply inlet390of large engine throttle10. Mechanical pressure regulator370is able to manage the low pressures from tank360and includes one or more conventional pressure regulators that use pressure-balanced diaphragms to vary effective orifice sizes and thereby control the pressure to within the preferred range at supply inlet390. Mechanical pressure regulator370preferably includes an integrated pressure sensor for providing upstream pressure data (i.e., equivalent to the pressure “P1” at supply inlet390) to ECM100via control link371. Whether or not a pressure sensor is integrated with regulator370, the preferred embodiment includes a pressure transducer951that measures the pressure at port230, which is upstream of throttle blade210and which is in fluidic proximity to supply inlet390, such that it is the same as P1, for reliable input on the actual pressure of the gaseous supply entering throttle10. Assuming all lines365,375and376are operatively sealed and connected to direct supply flow therethrough, supply flow from fuel supply350to large engine throttle10is enabled or disabled by On/Off operation of a mechanical shut-off valve380. Although manual valves may be used in certain alternative embodiments, valve380is preferably motor or solenoid actuated via oversight control by ECM100, as illustrated by the dotted-line control link381inFIG.10. When shut-off valve380is open, gaseous supply flow is induced by an operable pressure gradient between tank360and supply inlet390. Hence, with valve380open, fuel first moves through the heat exchanger and the mechanical pressure regulator(s)370, and the fuel is then directed through the valve380and into the fuel inlet390. Despite vaporization subassemblies and controls, the potential exists for the passage of vaporized natural gas or propane fuel that also contains droplets of liquid phase LNG or propane, which may occur for instance if the ports or conduits for heat exchange fluids become clogged. If any LNG or propane droplets remain in the fuel stream downstream from the mechanical pressure regulator(s)370, their subsequent vaporization may introduce dramatic pressure spikes into large throttle engine10, which would overwhelm large throttle engine10. In order to compensate for the possible introduction of LNG or propane droplets downstream of the heat exchanger, a pressure control loop may be inserted into the system in a position intermediate between the pressure regulator(s)370and the supply inlet390to large engine throttle10, preferably downstream of the heat exchanger and mechanical pressure regulator(s)370. In the event any errant droplets of LNG or propane enter into large engine throttle10, the delayed vaporization would likely lead to a spike of increased pressure at the supply inlet390of the large engine throttle10. If such a pressure spike is produced, the inserted pressure control loop preferably buffers the spike by venting back to the upstream side of the mechanical pressure regulator370. As other alternatives, one or more overpressure vents or bypass check valves can be included in line375and/or376to help divert vaporization spikes that would otherwise propagate and disrupt the control of large engine throttle10. Similarly, pressure spikes due to fuel vaporization upstream of the mechanical pressure regulator can also be vented to atmosphere and/or diverted to other containment further upstream in fuel supply350. By providing a multi-faceted strategy for control of such errant pressure spikes, namely through the inclusion of a heat exchanger in line365as well as one or more of the vents, check valves or the like as discussed above, preferred embodiments control and modulate the pressure introduced to the supply inlet390to reduce or prevent overwhelming the flowrate control of large engine throttle10. The fuel tank360may alternatively be embodied as any of a number of commonly available gaseous fuel sources, such as stationary gas pipelines, compressed gas cylinders, or other types of liquefied storage tanks with vaporization controls, together with conventional pressure regulators and the like. Preferably, most such alternatives still include some form of a fuel storage tank360that feeds fuel to large engine throttle10via a high-pressure mechanical pressure regulator370which regulates the pressure to a desired range for the supply inlet390. Again, from the high-pressure mechanical pressure regulator370, the fuel is fed through a fuel tube or supply line375, which preferably includes a shut-off gate valve380as shown. Downstream from shut-off gate valve380, the fuel supply line376is connected to the large engine throttle10at supply inlet390, at which point the fuel is preferably introduced into the gaseous supply throttle20of large engine throttle10. As will be understood by those of skill in the art, the supply line375may also include a fuel filter (not shown) or other conventional systems for monitoring and/or optimizing fuel supply conditions prior to introduction into large engine throttle10. Such other systems may include, for instance, fuel quality sensors connected to the engine control module (ECM)100and/or the PCB900of large engine throttle10for anticipating operating needs. The fuel supply350may also include a combination of several independent pressure regulators370(rather than just one), or may include additional pressure regulators that are integral to the fuel storage tank360. Referring again to the preferred embodiment as illustrated inFIG.10, the large engine throttle10includes a fuel supply350. Downstream of that large engine throttle10, the supplied fuel flow is then blended with air160for supplying a gaseous fuel-air mix150to internal combustion engine102. While theFIG.10arrangement is preferred, alternative embodiments in line with some broader teachings of the present invention may alternatively introduce some or all of the required air into the fuel upstream of large engine throttle10(as suggested by alternate air mixing flow arrow260′), albeit with corresponding challenges and possible compromises given that corresponding adjustments may be needed to account for the air flow introduction at whichever point it is introduced. Gaseous Supply Throttle20 Linked to the ECM100of engine102via the communication link illustrated by dotted line101, gaseous supply throttle20is adapted to provide rapid and highly accurate control of the actual {dot over (m)} supply flowrate at its outlet170in response to the {dot over (m)} flowrate signal105, for controlled delivery of the fuel supply to the fuel-air mixer161and subsequently the engine102. By its nature, gaseous supply throttle20is used to control gaseous supply flow from a primary fuel supply350(on the left inFIG.10) to an internal combustion engine102(on the right inFIG.10). Accordingly, gaseous supply throttle20is operatively positioned downstream of the fuel supply350and upstream of the fuel-air mixer161and engine102, such that it is plumbed and sealed to be part of a fluidly continuous fuel supply system during operation of engine102, with gaseous supply throttle20being intermediate the fuel supply350and the engine102. A detailed description of large engine throttle10with references to additional figures is made in ensuing paragraphs. For further optimization, the in-block microcontroller930and related control circuitry are preferably embodied on a single printed circuit board900(also visible inFIG.9). The in-block microcontroller930of PCB900is connected via data link101to receive the {dot over (m)} data signal105(and all other available data, including a P3data signal121, if needed, as discussed elsewhere herein) from ECM100. Data link101connects to ECM100and its control network, which is a CAN network in the preferred embodiment. Using the received data signals105,120, the printed circuit board900controls large engine throttle10, preferably without any external communication other than power and data connection101to the engine's ECM100. Although “CAN” is technically an acronym for controller-area-network, the “CAN” reference is a commonly used technical word that refers to a CAN network or to data received via a CAN network. On that note, it should be recognized that although a CAN network is the preferred communication link for communication of all commands, variables and other data received through line101by microcontroller930from outside of throttle system10, wireless, analog signals, digital signals, or other communication means may be used as alternatives while still embracing many aspects of the present invention. Also located on the PCB900is the CAN network connector960(visible inFIG.2B). As will be understood by those of skill in the art, CAN network connector960is a five pin connector. The five pins comprise a power pin, a ground pin, a CAN plus pin, a CAN minus pin, and a CAN termination pin. As will be understood by those of skill in the art, alternative embodiments could be direct (0-5V or 5-20 milliamp) data connections or any other known alternative for data connections that are otherwise suitable for an application such as large engine throttle10. Alternative embodiments may have eight pin connectors instead of the five pins for a CAN network. In the preferred embodiment, optimal fluid condition feedback is obtained from double sided transducer (“Delta-P sensor”)950by positioning the tips of its stove pipes (or a tube therefrom, as an alternative) in direct fluid contact with throttle chamber205(shown inFIG.4), while the base of transducer950is mounted directly on PCB900. With cross-reference toFIG.2B, Delta-P sensor950measures the differential pressure (“Delta-P”) between the upstream pressure port230and downstream pressure port240. Pressure sensor951measures the absolute upstream pressure (“P1”) from port230. Pressure sensor952measures the absolute downstream pressure (“P2”) from port240. With further cross-reference toFIG.2B, the stove pipe tips of pressure sensors951and952extend from PCB900through appropriately positioned sensor ports230and240in a side wall of throttle chamber205. To minimize clogging or other fouling of transducers950-952, ports230and240are preferably in a side compartment of throttle chamber205and are shielded through use of downwardly sloping passages or other measures as are known for use as contamination preventers. With cross-reference toFIG.6, optimal fluid condition feedback is obtained by positioning the sensor tip601of thermistor600directly within throttle chamber205, while the base602of thermistor600is soldered directly to thermistor PCB610. Thermistor600is a conventional thermistor that senses temperature at its tip601and has wire leads extending to the sensor tip601, although other forms of temperature sensors (or even sensors or the like for fluid conditions other than temperature) can be considered for use as alternatives for some of the same purposes. Throughout the control of in-block microcontroller930, embodiments of the present invention address long felt unresolved needs in the field through innovative approaches that overcome many of the limitations and challenges of the prior art. In accord with many of the teachings of the present invention, the industry is enabled to provide solutions manifested in large engine control systems that are readily adaptable to the power demands of numerous applications and are readily capable of highly accurately and precisely controlling supply flow across sizable dynamic power ranges in internal combustion engines. Engine102 With reference again toFIG.10, Engine102is a large spark-ignited internal combustion engine102of a type that uses gaseous fuel as its primary energy source, most preferably of a type that uses natural gas (NG) or vaporized propane (LPG) as its fuel. A large engine is defined here as any engine that is 30 liters or greater. Engine102is preferably used in stationary applications such as generator sets (hereinafter “gensets”) on natural gas compression skids. Alternatively, engine102may be used in large mobile applications such as trains, ships, mining trucks or other heavy duty vehicles. As is conventional, engine102has an ECM100or the equivalent, which continually monitors the operating conditions of various parts of engine102and its peripheral systems. Such an engine102may be operatively incorporated in any number of powered applications in alternative embodiments, as well as many other applications that may be now or in the future known in the art for being powered by spark-ignited gaseous-fuel internal-combustion engines. ECM100of engine102is connected via data communication lines181-182or other conventional means to monitor pressures, temperatures and operating states in or around numerous subsystems of engine102, such as its fuel-air handling system (that preferably includes a turbo charger172), a fuel-air throttle140, its ignition system, its combustion chambers180, its coolant system, its oil pressure, and its exhaust system, amongst others as are known in the art. Although alternative embodiments may use wireless connections for some or all of the data connections between ECM100and the various subsystems of engine102, preferred embodiments of ECM100are connected to send and receive analog or digital signals through wire harnesses or other forms of communication lines101,181,182,182a,182b,371, and381. Though represented inFIG.10by the various dotted-line communication links directly between the various components, communication lines101,181,182,182a,182b,371, and381are preferably embodied in the form of a conventional data network, such as a controller-area-network (“CAN”) network. As will be understood by those skilled in the art, ECM100is programmed to operate, in part, to determine the desired supply flowrate (“{dot over (m)}” or “mdot”)105at any given instant in time, based on current operating conditions of engine102in comparison to current user demands. As the desired m flowrate is determined by ECM100, the ECM produces a corresponding m data signal105that represents the current m flowrate demand for engine102. As the desired m flowrate is determined by ECM100, the corresponding m data signal105is conveyed by communication link101to the microcontroller930of large engine throttle10, and large engine throttle10operatively serves to instantaneously and accurately deliver as much from throttle system outlet170. After the flow control by large engine throttle10, the controlled flow of gaseous supply from the throttle system outlet170is directed to fuel-air mixer161where it is preferably mixed with air160, to produce a combustible fuel-air mix150. Preferred embodiments use a flow of filtered air160. The intake air160that is directed into the fuel-air mixer161may be drawn from ambient air in alternative embodiments, with or without pressure compensators, albeit with performance compromises. Fuel-air mixer161is preferably a venturi-like mixer or another type that does not use moving parts in the supply flow, thereby maximizing durability and fuel/air mixture homogeneity of flow conditions actually delivered to combustion chambers180. Most preferably, fuel-air mixer161is in a form that includes a fuel ring, to help preserve the benefit of the accurate {dot over (m)} flowrate control provided by throttle system10. Once the proper fuel-air mixture150is provided by fuel-air mixer161, that mixture150flows toward engine102. The fuel-air mixture150passes through a turbocharger172. The turbocharger172takes in recirculated gas from the pre-turbo exhaust171, mixes it with fuel-air mixture150and compresses it. After leaving the turbocharger172, the fuel-air mixture150passes through a turbo aftercooler174. The turbo aftercooler174cools fuel-air mixture150before it enters the engine102. It is necessary to reduce the temperature of the fuel-air mixture to allow for a denser intake to the engine102, thereby increasing the output of the engine102. The post turbo exhaust gas173flows into a three-way catalytic converter (TWC)175. As will be understood by those of skill in the art, the TWC175reduces pollutants prior to the exhaust gas being released to the environment. Although not illustrated in the drawings, those of skill in the art will understand that preferred embodiments would include various components that are not shown. Moreover, other components like filters and pressure relief valves are also not shown. With respect to any such simplifications and omissions from the drawings, it should be understood that preferred embodiments include them in such character and configuration as would be generally understood within the discretion of those of skill in the art. The flow of fuel-air mixture150is controlled by fuel-air throttle140, which is preferably an electronic throttle that further facilitates preservation of the highly accurate flowrate control provided by the supply throttle10inFIG.10. Accordingly, fuel-air throttle140is preferably also constructed with the same basic structure and software as throttle10, albeit preferably with adaptations to accommodate the different pressure ranges that would be experienced downstream of mixer161and perhaps with less protection of internal components against the corrosive effects of more concentrated fuels, as would be encountered upstream of mixer161. BecauseFIG.10plumbs and uses throttle10to control the mass flowrate of the fuel itself, that type of throttle deployment is sometimes referred to as mass-flow-gas throttle (or an “MFG” throttle). In contrast, the fuel-air throttle140that is used to achieve highly accurate control of the mass flow of the fuel-air mixture150is sometimes referred to as a mass-flow-air throttle, or an “MFA” throttle, irrespective of whether or not the fuel is mixed with the air at the point of that control. Preferably, the fuel-air throttle140is also constructed according to the teachings of the present invention, with the same basic structure as the supply flow throttle10that is used as an MFG throttle to control the mass flow of the fuel by itself. Hence, the highly accurate fuel supply flow of the MFG throttle10inFIG.10is preferably combined with highly accurate air supply mass flow control achieved by a fuel air throttle140constructed according to the same basic teachings as the MFG throttle10. Alternatively, complete and highly accurate mass flow control can also be achieved by combining an MFG throttle together with an MFA throttle that is plumbed in the air supply160upstream of the fuel-air mixer161. Either such combination, either the one illustrated inFIG.10or the alternative combination of using a similar throttle to control the mass flow of air160by itself, enables comprehensive mass flow control of all supply flows for combustion. Moreover, generally accurate overall control might also be attainable by just controlling the mass flow of the fuel, without actively controlling the mass flow of the air if other reliable data is used to calculate that mass flow of the air, such as through use of oxygen sensors in combination with pressure, temperature and the like. Whatever the choice for a specific application, we trust that those of skill in the art will understand where and how to include such throttles for the different purposes to achieve the different combinations for overall mass flow control. Whatever the choice, the resulting fuel-air mixture150is then operatively introduced into combustion chambers180of engine102under the control of ECM100. Within combustion chambers180, the fuel-air mixture150is then operatively spark-ignited to cause working combustion. Surprisingly, the use of such an MFG throttle together with such an MFA throttle enables a dramatically streamlined development cycle for engines. Whereas large natural gas spark-ignited internal combustion engines have historically required considerable time and expense to finalize and validate the engine design prior to commercial release, the highly accurate mass flow control of the present invention enables a greatly simplified development, conceivable without any test cell expense. Although the industry will likely continue the use of test cells for finalizing designs, the accurate controls enabled by the present invention will allow much more relaxed standards in the process, not to mention the ability to achieve highly accurate mass flow control despite highly variable quality in fuel quality, air composition, and other environmental factors. Fuel Property Determination In situations where the quality and composition of the fuel being supplied to an engine is known and consistent, the fuel flow is a measured and a known value, and air flow is either measured or inferred, among other variables. Based on these measurements or inferences, the engine may be accurately adjusted to achieve maximum power while remaining compliant with emissions standards. However, in situations where the quality and/or composition of the fuel is not known or is variable over time, the process for adjusting the engine can be difficult and may often require manual sensing to ultimately provide accurate mass flow of fuel based on the demands of the engine. It is in this context that the disclosed systems and methods can provide much improved automatic adjustments to the engine based on accurately determining the mass flow of air and mass flow of fuel at any given time during operation of the engine. When fuel composition varies as the fuel is supplied over time to the engine102, on-the-fly adjustments for maintaining efficient operation and maximum power of the engine102and also for keeping the engine operation within emissions compliance standards, can be difficult. In order to resolve this difficultly and more efficiently adjust the engine on-the-fly, two throttles, as shown and described herein, can be employed in a system configuration that provides the necessary data points to make real-time determinations for adjusting or calibrating the engine based on fuel quality. To achieve as much, the fuel supply microcontroller930(or the ECM100or another controller or group of controllers, in alternative embodiments) is programmed to infer fuel quality characteristics using a process as represented by the flowchart ofFIG.11A, described further below. In keeping with at least some aspects of the system as illustrated inFIG.10, two throttles are provided: one as a mass-flow-gas (MFG) throttle20and the other as a mass-flow-air (MFA) throttle140. Looking toFIG.11A, shown is a simplified flowchart that is representative of methods used to infer fuel properties of a fuel supply, wherein the fuel supply has unknown fuel properties. More particularly,FIG.11Aillustrates the determination of the mass flow of the fuel (“MFG”) at step450, and the mass flow of the air (“MFA”) at step450. Beginning at point400, the mass flows of air and gas are determined first, shown as step410. At step415, the actual mass flow of air is determined from mass flow sensors located in the MFA throttle140. Moving to step420, an actual mass flow of gas is determined using an algorithm programmed in the MFG throttle20microcontroller. At step430, the exhaust gas oxygen levels are read by the EGO sensor190; this step provides the actual air-fuel ratio, whereby an air-fuel ratio offset value can be determined. The process for determining offset values for the air-fuel ratio and other engine operations will be discussed in later sections. The controller930(or another controller or combinations of controllers in alternative embodiments) is able to determine the mass flow of both the fuel and the air through use of two throttles10embodied according to the teachings of the present invention. The controllers determine results of combustion through monitoring of oxygen sensor190. InFIG.10, oxygen sensor190is positioned in the exhaust manifold, downstream from the MFA140is an, preferably in the form of an exhaust oxygen sensor. As such, sensor190is positioned and configured to sense the oxygen content in the exhaust. The oxygen sensor190will provide a measurement to the ECM100of oxygen concentrations or deficits in the exhaust gas. The oxygen levels in the exhaust can be correlated to characteristics of either a rich or lean air-fuel ratio. As it is known by those of skill in the art, the term “rich” is used to describe an air-fuel ratio that has more fuel than air. Inversely, the term “lean” is used to describe an air-fuel ratio that has more air than fuel. With respect to engine performance demands, a rich or lean air-fuel ratio may be desired to achieve certain load limit applications. The quality of the fuel also may determine if an air-fuel ratio is rich or lean. Natural gas directly from a wellhead has inconsistent chemical compositions. Depending on the source, unrefined natural gas will have properties associated with concentrations of any it's constituent gases. Typically, natural gas has high concentrations of Methane CH4; however, amounts of Ethane C2H6, Propane C3H8, Butane C4H10, Pentane C5H12, and Hexane C6H14 may also be found. Methane, being the lighter fuel, will show lower oxygen levels in the exhaust. Heavier fuels, like Propane and Ethane, will show higher oxygen levels in the exhaust. It should be noted, such mass flow determinations are determined by the throttle controllers in the course of operating the throttles20and140in the preferred configuration illustrated inFIG.10. At step440, fuel properties can be interpolated based on the offset values. A feedback loop, shown as arrow450, transmits engine operation offsets to respective equipment, wherein the MFG throttle20and MFA throttle140are adjusted to meet engine demands. At step460, fuel properties are then inferred based on the methods described while referencingFIG.11Aand additional methods described in later sections. FIG.11Bis a flowchart intended to further explain, in more detail, the methods described inFIG.11A. Looking at the starting point400′, the initial Fuel properties and variables are assume at step401. The mass flow of air and the mass flow of fuel are calculated at step404based on current inputs403from MFG20and MFA140. In addition to inputs403, offset correction values, shown at step430′, applied to the MFG20and MFA140actuators are also factor into determining the mass flow of air and mass flow of fuel. At step402, the true air-fuel ratio, shown as AF Ratio, is determined. At step405, the ideal air-fuel ratio, shown as ideal AF ratio, is determined. The percent error of the air-fuel ratio is calculated at step406. The MFG20and MFA140offsets used at step430′ are determined at step408. The MFG20and MFA140offset determinations are based off of input407from the current EGO sensor measurements. If there are no corrections needed, shown as the YES direction at step409, then fuel properties can be interpolated using the calibrated lookup tables, referred to as fuel tables in step440, and the percent error of the air-fuel ratio. An example of the fuel tables can be seen inFIG.12. The fuel properties then can be used as desired shown at step460′. If correction are needed, shown as NO at step409, then MFG20and MFA140actuators need to be adjusted, shown at step430′. The ECM uses an engine integrated control system (“EICS”) that is linked up to a database program that includes calibratable manufacturer suggested engine ratings. The database enables the EICS to access numerous manufacturer suggested engine specifications. To further elaborate how the database is used in the present disclosure, there are specific fuel properties that a fuel supply must maintain to ensure optimization of engine performance. To simplify the concept, a fuel with properties similar to gasoline will have adverse effects on an engine designed to operate on fuel with properties similar to diesel, furthermore gasoline and diesel can have various octane numbers that are associated with increasing levels of engine performance. The engines associated with the present disclosure are designed to operate on natural gas that, much like the octane number, can be rated with a methane number or BTU content. The fuel properties of the fuel supply can be compared to the manufacturer suggested fuel properties, thus enabling the EICS to calculate associated offset values. The stoichiometric air-fuel ratio is a theoretical value that, with a known or estimated mass flow of air, can be used to calculate a theoretical mass flow of gas. As it is known by those of skill in the art, a simple method for calculating the air-fuel ratio is to divide the estimated mass flow of air by the mass flow of gas. This convention coincides with the ECM's100ability to instantaneously demand a specific mass flow of gas depending on performance needs. To obtain a value for a desired mass flow rate of gas, the ECM100conducts a percent error analysis, shown at step412inFIG.11B, that quantifies the accuracy of the actual air fuel ratio to the ideal air-fuel ratio. This analysis is used to determine the proximity of actual mass flow values to desired mass flow values, wherein offset values are determined, shown in block450′. The offset values demanded by ECM100, whereby the MFG throttle20is adjusted to meet said offset values Similarly, the mass flow of air can be determined such that the MFA throttle140, positioned downstream of the MFG20, provides the mass flow rate of air to the ECM100. For the purposes of describing the current disclosure, the mass flow of air will be treated mathematically as a known or estimated constant, therefore MFA140adjustments will not be explicitly described. However, MFA140adjustments are within the capabilities of the current disclosure. The methods for achieving MFA140adjustments are identical or similar to achieving MFG20adjustments. Note that it should be understood that the MFA throttle140, when positioned downstream of the air intake and downstream of an air/fuel mixer161where the air is mixed with the fuel, would actually be measuring the mass flow of a mixture of air and fuel, such that the mass flow of the air would be determined by subtracting the mass flow of the fuel from the mass flow of the mixture. It should be understood, nonetheless, that a second throttle in certain alternative embodiments can be positioned in an air supply upstream of fuel-air mixer161such that it directly determines and controls the mass flow of the air rather than the mixture. As previously mentioned, unrefined natural gas has discontinuities of chemical composition that, if routed directly from a natural gas well head to an on-sight engine, lead to volatile engine performance due to inconsistent fuel quality. In addition to conducting an air-fuel ratio error analysis, as described at step440′, the ECM100also conducts closed-loop error corrections, which then can be used to infer fuel properties. The closed loop error corrections are made using the resulting percent error value described at step440′. By utilizing closed-loop correction, exact fuel property values, such as BTU content “BTU” and Methane number “MN”, can be interpolated based on fuel tables, shown inFIG.12, or response curves, shown inFIG.13, included in the database of manufacturer's suggested engine ratings. Looking toFIG.11B—at step440′—fuel quality can be inferred from the air-fuel ratio closed-loop error corrections generated from the ECM100. Assuming the engine has been calibrated to operate with certain fuel specifications, fuel properties can effectively be interpolated from a table of properties known to be associated with the calculated error interval. Using a database program, such as GERP, at step420′, fuel specifications recommended by the engine manufacturer are accessed and used to infer fuel properties based on the closed-loop error. For example, if an engine is calibrated to operate with propane as the base fuel, there will be a closed-loop error associated with the characteristics of the incoming fuel source. The closed-loop error determines the amount of correction needed to achieve properties similar to the base fuel. In the current disclosure, corrections made to the MFG20and MFA140throttle positions are described, however corrections to other equipment settings may be applicable to alternative embodiments. It should also be understood that, as suggested by the feedback path450inFIG.11A, that the inferences about fuel quality can be iteratively improved by using the inferred fuel quality characteristics in the next determination of mass flows at step410. Typically during engine operation, if it is determined through measurement that the air/fuel ratio changes from the preferred ratio (rich, lean, or stoichiometric) based on the particular application, one can expect that the change results from either a change in the air or a change in the fuel. More specifically, for a given calibrated engine102, changes in closed-loop correction are likely related to air flow changes or fuel flow/fuel property changes. Since air flow for a given speed and load condition can now be measured, changes in closed-loop correction can more likely be attributed to fuel property changes. Thus, properties related to air flow are unlikely to change and can be monitored with an oxygen flow sensor190. However, given that the above-identified parameters are known based on the configuration of the MFG throttle20, the MFA throttle140, and the oxygen sensor190, it can be more accurately inferred that there has been a change in the fuel, more particularly a change in the fuel composition or fuel properties. A number of fuel properties may be inferred based on the known data related to the mass flow of fuel, mass flow of air, and the air/fuel ratio. These fuel properties can include, but are not limited to, British Thermal Unit (BTU) content, Wobbe Index, methane number, stoichiometric fuel/air ratio, specific gravity of the fuel, hydrogen/carbon ratio, ratio of specific heats of the fuel, etc. Although the following description particularly references BTU content, it should be understood that any of the identified fuel properties may be inferred. Nonetheless, generic reference is sometimes made to either “fuel property” or “fuel quality”, which should be interpreted as all-encompassing generic references to any of those fuel properties mentioned above, as well as to still any other fuel quality properties that characterize the quality of natural gas in fields related to natural gas engines. By knowing the mass flow of air, the mass flow of gas, and the air/fuel ratio, the disclosed system10can infer the BTU content of the gas. All of these parameters are then supplied to the ECM100. In turn, knowing the BTU content of the gas, the ECM100, by execution of its proprietary software, is programmed to automatically adjust particular engine settings to maintain efficient engine operation that results in appropriate power output and preferably maintaining the engine operation in compliance with applicable emissions standards. For instance, changes can be made to phi targets (pre- or post-catalyst), spark timing, and/or maximum allowable load based on the BTU input. Furthermore, another check can be used whereby spark timing is adjusted and knock level is measured with a knock sensor (not shown). This can help correlate the expected relationship between BTU content and methane number. One general application in which the above principles and system configurations are especially beneficial is engines incorporated in various applications in oil and gas fields. This includes, but is not limited to, generator packages driving downhole electric pumps, engines incorporated into gas compression systems, and other like uses. For example, certain applications in oil and gas fields incorporating an internal combustion engine can be supplied fuel, with the fuel being the gas from a gas well. Because the composition of the gas out of the well varies over time, the BTU content of such gas is typically unknown without a person on-site taking measurements to determine as much, for instance using a gas chromatograph. Instead, as with the currently described systems and methods, having the ability to more accurately determine the BTU content of the gas out of a well without having to physically take measurements but relying on the information gathered by using the systems and methods as herein described, clearly represents an improvement, particularly when it is crucial to be able to distinguish between buy-back gas and sell gas based at least in part on the composition of the gas. To further elaborate, on typical systems having an internal combustion engine being supplied with gas directly from a well, a person would have to physically visit the site to enter particular setup points for the operation of the engine. The gas is measured, the methane number of the gas is determined, the spark timing can be set based on known information, and based on all of that information, the engine might be derated. Because the composition of the gas out of the well often fluctuates, in order to keep the engine operating with emissions standards, a person must physically be on site and make adjustments to the engine for this purpose. Utilizing the disclosed system and methods, particularly providing an MFG throttle and a MFA throttle that allow for very accurate measurement of fuel and air, the composition of the gas (BTU content) can be accurately inferred and the adjustments to the internal combustion engine in this scenario can be done without requiring physical intervention. In particular applications, on-the-fly closed-loop corrections can be made with respect to the fuel supplied to the engine102when the system10infers one or more fuel properties, and based on that determination, a correction is required. Fuel flow is measured and a known value. Using oxygen sensor190, the air/fuel ratio is determined, and that value is communicated to ECM100. Thus, the fuel flow and air flow are known. In order to accurately determine whether a closed-loop correction is necessary, alarm faults are setup in ECM100. These alarm faults are calibratable. For instance, if the closed-loop correction value is zero, this indicates that no intervention is necessary to change the fuel flow. However, if the closed-loop correction value is −15, this indicates that the system10has to pull back 15% of the energy or the BTU content or the fuel flow rate. In other words, to maintain sufficient power, ECM100commands that mass fuel flow be reduced by 15% in order to maintain the preferred air/fuel ratio. In this given example, alarm faults of +1-15% can be set in ECM100, such that if the indication is that the air/fuel ratio is off by +/−15%, ECM100will command an increase or decrease of the mass fuel flow to return the air/fuel ratio to the preferred value. Fault alarm settings are dependent on the particular application in which MFG throttle20and MFA throttle140are employed. Furthermore, because the mass flow of fuel, the mass flow of air, and the air/fuel ratio are known, knowing the closed-loop correction value, particularly a value other than zero, indicates to an operator that the fuel properties have changed. It will be understood that another application of the systems herein described that is contemplated is the use of the large engine throttle strictly as a metering device such as may be used on a gas pipeline. Given that the large engine throttle is accurate for measuring flow, particularly in a low-pressure application such as a large pipeline, wherein the difference in upstream and downstream pressures is small, the application of the large engine throttle as a flow metering device can replace more complicated and/or more expensive devices and techniques. It will be understood that still another application that can benefit from the systems and methods herein disclosed is use in gas compression systems in oil and gas fields. More particularly, once the fuel property information has been determined, the ECM can output that fuel property information for a variety of other important uses, such as is represented at step460of the flowchart inFIG.11A. As an example, the fuel property information can be sent to a compressor that is compressing the same general supply of natural gas for more accurate prediction and control of compressor power, as well as compressor and internal stage information. Turning toFIG.11C, shown is the strategy for determining fuel properties such as fuel quality, load limit offset, phi offset, and spark offset.FIG.11Celaborates further the methods used to determine the concepts inFIG.11AandFIG.11B. AlthoughFIG.11Cexplicitly describes methods to determine fuel quality, load limits, phi offset, and spark offset, other properties, such as BTU content, can be determined with similar methods. For demonstrative purposes,FIG.11Cincludes various sections that are bracketed for quick reference. The section shown with bracket1050includes the process used to determine a closed-loop error associated with the air fuel ratio of a fuel supply with unknown properties. The section shown with bracket1051includes the interpolation methods for determining fuel quality, spark advance, and load limit. Looking at starting point1000, the true mass flow of air1001, shown as mdot_a_i, determined from mass flow sensors in the MFA140throttle, represented as box1002. Various alternative embodiments may utilize only one mass flow throttle. Some of those alternative embodiments will use MFG for controlling the mass flow of gas to the extent that corresponding assumptions can be made about the mass flow of air. Looking to box1003, the true mass flow of air1001is divided by the true mass flow of gas, shown as 1/mdot_g_i, based on sensed readings from the MFG20throttle control algorithm990, represented as box1002′. The output from box1003is the true air-fuel ratio1004, shown as AF_i. The true air-fuel ratio1004is subtracted from the ideal air-fuel ratio1005, shown as AF_stck. The ideal air-fuel ratio1005is determined using methods represented in box1028, the values and methods represented in box1028are determined as a part of the engine calibration process. The air-fuel differential1007, shown as delta_AF_i, between the true air-fuel ratio1004and the ideal air-fuel ratio1005is calculated. Then, represented in box1008, the air-fuel differential1007is divided by the ideal air-fuel ratio and multiplied by 100, which results in a percent error value1009. The percent error value1009, shown as +/−e, branches off to be used in determining fuel properties, which will be discussed later, and in determining adjustments for the MFG throttles20. Use of the percent error value for determining throttle corrections will be referred to as closed-loop corrections, whereby the representative “loop” process is enclosed by the dashed box1014. The percent error is multiplied, represented as box1010, by the true air-fuel ratio1004, which results in an air-fuel ratio adjustment value1011, shown as +/−AF_adj. The air-fuel adjustment value is transmitted to the throttle microcontroller930. As previously mentioned, if the mass flow of air is known, estimated, or held constant, adjustments to air-fuel ratio can be effectively be made by adjusting the mass flow of gas. For the purposes of describing the current disclosure in terms of simple inputs and outputs, the throttle control algorithm990is shown inFIG.11Cas receiving the air-fuel adjustment in the form of a demanded mass flow of gas value1012, shown as mdot_g_0. The throttle control algorithm990, with the use of formulas described later, correlates the demanded mass flow to a specific blade angle1013, whereto the MFG throttle20will adjust. Looking back to the percent error value1009, this value is also used to determine fuel properties. The percent error value1009is associated with an instantaneous air-fuel ratio. To determine fuel properties of the fuel supply, Calibrated Lookup Tables, represented as box1006, must be used, whereby fuel properties can be interpolated. An example of the calibrated lookup table can be seen inFIG.12. The calibration method associated with the current disclosure includes the determination of percent error values associated with known fuel types. For example, assuming an engine is designed to operate on propane, the calibration process would include operating said engine with other known types of fuel where the properties are already known. As the fuel type drifts further from propane, there will be an air-fuel ratio percent error associated with said fuel type; propane would have an error of 0%. To elaborate further, if a fuel like Butane were to be used in the calibration process for an engine designed to operate on propane, there would be an air-fuel ratio percent error associated with Butane. Outside of the calibration process, if the percent error value1009were to be between the values of Butane and Propane, then the properties of the unknown fuel could theoretically be interpolated with some degree of accuracy. Moving forward, the percent error value1009is entered into the Calibrated lookup tables. The result1016, shown as delta_e, is then used in a standard interpolation equation, shown in box1018a, whereof variable y represents the fuel quality. It will be evident to those of skill in the art, how to apply the equation shown in1018a,1018b,1018c. The interpolation equation is also used, with other inputs, to determine the engine's spark advance, as seen in box1018band load limit, as seen in box1018c. Although it is not shown, BTU content of the fuel supply is determined using methods similar or identical to determining Fuel Quality. The equation shown in box1018bis used to solve for the demanded spark advance, Inputs for equation1018a,1018b,1018c, with the exception of the percent error value1009, are determined from the calibrated lookup table1006. Looking back to equation1018b, the output is the spark advance1027adjustment, whereof would be demanded by the ECM100. It should be known to those of skill in the art, that spark advance refers to the combination of ignition timing as it relates to piston position and crankshaft angle. Looking to the output of equation in box1018c, where y represents the ideal load limit. The ideal load limit1019, value, shown as LL_0, is used to determine the maximum blade angle of the MFA throttle; the methods used to determine the max blade angle are represented as box1024. The output of box1024is feeds into the throttle algorithm990, wherein the blade angle1013′ of the MFA throttle140will not violate the maximum blade angle value. Looking back equation1018a, the determined fuel quality1025of the fuel supply is used to determine the ideal phi value1028, or can be reported1034. The fuel quality can be reported as a BTU content or a methane number. It should be noted thatFIG.11Cis intended to aid in describing the concepts of the current disclosure, wherein methods for determining other associated fuel properties are beyond the scope of the description's purpose. Fuel Quality Control Strategy Looking toFIG.12andFIG.13,FIG.12is a representative fuel table1200as previously described in the example of the calibration process from the previous section. Referencing the calibration example, the estimated closed loop error associated with propane, along with the fuel properties, is shown in row1201. If the systems closed loop error falls between two known closed loop errors, shown for demonstrative purposes as1203, then the rows above and below the system's value are used to interpolate any desired fuel property. The manufacturer specifications are shown in columns1202.FIG.13, shows a response curve1300used to determine the fuel quality of a fuel source. Depending on the value of the load limit, calculated using the previously described interpolation method, a maximum load limit is associated with 100% to 75% natural gas1303, whereof the fuel quality would be reported as 100 to 75. A minimum load limit is associated with 0% natural gas and 100% propane1304. Because there is no slope between 100 and 75 fuel quality, load limits between points1301and1302would result in an observable fuel quality. Point1301is at 75% fuel quality and point1302is at 0% fuel quality. The fuel quality control feature of the current disclosure uses an Engine Integrated Control System (“ECIS”) to determine simplified fuel quality data that may be useful to onsite personnel. The ECIS has interactive software that allows a technician to input fuel property values for calibration. The software also allows the technician to manipulate the modes of ECIS operation. Depending on if the fuel quality control feature is in static or dynamic mode, the fuel quality data can also be used to determine the aforementioned MFG throttle20or MFA throttle140adjustments necessary to maintain engine performance. Common methods for determining fuel quality from a natural gas wellhead involve measurements of BTU content and Methane Number, however, inexperienced technicians or other personnel may have difficulties interpreting the measurements. With the teachings of the current disclosure, a simple 0-100 percent scale can be used to describe the quality of fuel from a natural gas wellhead. A simplified response curve, shown inFIG.13, illustrates the relationship between fuel quality and engine load limits. The 0-100 scale is effectively a ratio of the fuel supply's natural gas content to propane content, whereas natural gas “NG” has a fuel quality of 100% and liquid propane gas “LPG” has a fuel quality of 0%. For example, a reading of 25% fuel quality indicates that the wellhead produces fuel that behaves as a mixture of 25% natural gas and 75% propane. Utilization of the current disclosure's fuel quality control feature is dependent upon the AFR closed-loop error offset value. The closed-loop error offset value is entered into a fuel calibration table similar to the table shown inFIG.12and uses block multiplication to interpolate values for BTU content, AFR “phi”, spark advance, and fuel quality. The interpolated values are used to determine offset values that are demanded by the ECM100. The conceptual paths for interpolating said values can be seen inFIG.11B. Upon startup of the ECIS, a base fuel BTU value is used to initialize the system. The fuel quality control feature is automatically enabled if the incoming fuel is natural gas, however, if the incoming fuel type is different or manually switched, the closed-loop error generated from the NG calibration will remain constant; in other words, any fuel error adjustments will remain relative to the NG properties. As previously mentioned, the fuel quality control feature has the capability to operate in a dynamic mode or a static mode. When dynamic mode is enabled, the closed-loop error offset value is used to initialize the EICS fuel table block multiplier and continuously updates BTU content and MN with respect to the MFG20and MFA140provided mass flow rate readings. The interpolated values for manufacturer recommended spark/phi/load limit, which are calculated from the updated BTU content and MN, are used to automatically adjust associated equipment. If static mode is enabled, the EICS initializes in the same manner as dynamic mode, but the values for BTU content, MN, and manufacturer recommended spark/phi/load limit remain constant relative to the base fuel. Static mode allows equipment adjustment that is determined by the one-time base fuel properties used to initialize the system. To simplify the conceptual difference, static mode allows wellhead fuel quality to be observed without making adjustments relative to said wellhead fuel quality. Application of the static mode would be valuable once the properties of a fuel source is determined and can be used as a base fuel for calibration. For example, a natural gas well in the Permian Basin of Texas may supply fuel of quality that differs from another geographical source, like the Eagle Ford Group in Texas. To elaborate further, calibration of the system can be based off a geographical fuel supply; relating to the previous example, natural gas from either the Permian Basin or Eagle Ford could be used as the calibrating base fuel. If the methane number fuel trim feature is enabled, the air fuel ratio or “phi” can be adjusted accordingly. In dynamic mode, phi is adjusted according to MN interpolated using the closed loop error value and the fuel calibration table. If the interpolated MN is greater than or equal to the MN associated with the manufacturer recommended spark/phi specifications, phi is adjusted. The adjusted phi value generated from this system is used to make corrections in mass flow rate of gas or air. The correction values are demanded by the ECM100to the MFG20and MFA140throttles. In static mode, the interpolated MN value of the fuel source can simply be looked up from the fuel calibration table. Spark advance values are controlled by the previously mentioned database program compensation mode. When the database program is enabled, manufacturer recommended values for spark advance, phi, and load limits can be used by the ECIS. The database program uses the closed loop error input to interpolate a spark advance value from the fuel table. After the spark advance is determined, the adjusted offset amount applied by the ECM100can be observed as well as the resulting spark advance from said adjusted offset amount. The above method for determining spark advance is only enabled when the fuel quality control system is enabled. If the fuel quality control system is not enabled, the database program determines the spark advance based on a one time calibrated 0-100% range; natural gas has a database program value of 0% and liquid propane gas has a value of 100%. The database program percentage value depends if the fuel supply behaves more like natural gas or propane. To control engine load limits, the fuel type must be NG and the fuel quality control system must be enabled. Determining the load limit is also done using the fuel table interpolation method. The closed loop error is entered as an input value and the load limits are interpolated based off the manufacturer's recommended values for the engine's load limit. After the load limits are determined, the fuel quality can be determined by interpolating values based off a response curve similar to the illustration inFIG.13. Throttle Control Strategy As will be understood by those of skill in the art, the following mass flow rate equations are used to describe the non-choked flow of gases through an orifice. Equation (1) is the mass flow rate equation for ideal gases and equation (2) uses a gas compressibility factor “Z” to correct for the mass flow rate of real gases. m.=CA22ρ1P1(kk-1)[(P2/P1)2/k-(P2/P1)(k+1)/k](1)m.=CA2P12MZRT1(kk-1)[(P2/P1)2/k-(P2/P1)(k+1)/k](2) In these equations, “in” is the desired mass flow rate demanded by the ECM; “C” is the dimensionless orifice flow coefficient; “A2” is the cross-sectional area of the orifice hole (“effective area”); “ρ1” is the upstream real gas density; “P1” is the upstream gas pressure; “k” is specific heat ratio; “P2” is the downstream gas pressure; “M” is the gas molecular mass; “T1” is the absolute upstream gas temperature; “Z” is the dimensionless gas compressibility factor at “P1” and “T1”; and “R” is the universal gas law constant. Values for “Z” and “R” are unique to specific gases, or in the case of the current disclosure, a specific fuel type. These values can be held constant with respect to the calibrating base fuel. Values for “C” can be found using the pressure differential “deltaP” in the MFA or MFG throttle valve. With reference toFIG.10, the throttle control algorithm990determines the A2“effective area” needed to achieve the desired m mass flowrate using equation (2). The algorithm essentially rearranges equation (2) so that the effective area is calculated and correlated to the throttle blade angle. P2, P1, and T1are measured as previously described and these values are used in equation (2). Corrections to the mass flow can be correlated to “effective area” corrections needed to achieve the desired mass flow. The microcontroller930is constantly utilizing the throttle control algorithm990to attain precise m flowrates while the parameters change. Once the “effective area” A2is determined by throttle control algorithm990, a signal is transmitted to brushless motor700. Brushless motor700is an actuator that controls the movement of throttle shaft710, thereby adjusting throttle blade210of gaseous supply throttle20until the desired “effective area” A2is achieved. Brushless motor700is preferably a fast-acting actuator, preferably operable to move the throttle blade210through its entire range of motion in fifty milliseconds or less. Fast-acting actuators are preferably operable to move the actuated element through most of its operable range of motion (preferably from 20% to 80% of stroke), if not all of that operable range, in fifty milliseconds or less, although many other types of actuators are still likely to be suitable as alternatives, especially to the extent particular claim elements are not expressly disclaimed to require particular fast-acting characteristics. Operating Pressures—Low Pressure Although it will be understood that adaptations may be made for other upstream conditions, the pressure in the supply line376at the supply inlet390is preferably controlled by mechanical pressure regulator370to be approximately at a gauge pressure slightly above one atmosphere, although when throttle10is used as an MFG throttle, pressures could be as high as 2.5 bar absolute or, in the case of MFA application, as high as four bar absolute. Although not necessary for highly accurate mass flow control, some methods of controlling large engine throttle10may also be further tuned to achieve the desired control depending in part on actual or estimated fluid conditions even further downstream, such as by a downstream sensor121monitoring pressure (designated as “P3” for our purposes) that is monitored by ECM100and for which a representative data signal120is continuously available from ECM100(or from the data network associated with ECM100). The particular P3value of data signal120represents any available data stream from engine102that is characteristic of pre-combustion fluid pressure within engine102. Such a downstream sensor121may be a conventional temperature and manifold absolute pressure (TMAP) sensor module located in the engine's intake manifold downstream from fuel-air throttle140. In addition to, or as an alternative to, a conventional TMAP sensor121, downstream data can also be gathered from a conventional throttle inlet pressure (TIP) sensor module upstream of fuel-air throttle140. Again, though, despite the plausible benefits of knowing the further downstream pressure P3for some variations of the invention, most preferred embodiments of throttle10omit consideration of P3data from sensor121as unnecessary, opting instead for simplicity and cost saving. Alternative Fuels Gaseous fuel for these purposes means a fuel that is in the gaseous state at standard operating temperatures and pressures. In presently preferred embodiments, the gaseous fuel is natural gas, derived from either a liquefied natural gas (LNG) or compressed natural gas (CNG) storage state. While the most preferred embodiments are adapted for use with these fuels, adaptations will be evident to those of skill in the art for use of aspects of this invention with other fuels in alternative embodiments. Such alternative embodiments are adapted, for instance, for use with hydrogen or other gaseous fuels such as propane, butane or other gas mixtures, including those common with liquefied petroleum gas (LPG) mixtures. Indeed, although the present invention is focused on the particular fields to which the preferred embodiments apply, it may also well be that some aspects of the invention may be found revolutionary in other fields as well. Alternatives in General While the foregoing descriptions and drawings should enable one of ordinary skill to make and use what is presently considered to be the best mode of the invention, they should be regarded in an illustrative rather than a restrictive manner in all respects. Those of ordinary skill will understand and appreciate the existence of countless modifications, changes, variations, combinations, rearrangements, substitutions, alternatives, design choices, and equivalents (“Alternatives”), most if not all of which can be made without departing from the spirit and scope of the invention. Therefore, the invention is not limited by the described embodiments and examples but, rather, encompasses all possible embodiments within the valid scope and spirit of the invention as claimed, as the claims may be amended, replaced or otherwise modified during the course of related prosecution. Any current, amended, or added claims should be interpreted to embrace all further modifications, changes, rearrangements, substitutions, alternatives, design choices, and embodiments that may be evident to those of skill in the art, whether now known or later discovered. For example, other alternatives associated with the current disclosure with one mass flow throttle may use a mass flow throttle that controls the mass flow of an air-fuel mixture, which for convenience may be referred to as MFA/MFG. Still alternatives will be evident to those of ordinary skill in the art. In any case, all equivalents should be considered within the scope of the invention, to the extent expressly disclaimed during prosecution or to the extent necessary for preserving validity of particular claims in light of the prior art. | 92,853 |
11859569 | DETAILED DESCRIPTION Before turning to the figures, which illustrate certain exemplary embodiments in detail, it should be understood that the present disclosure is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology used herein is for the purpose of description only and should not be regarded as limiting. Referring generally to the FIGURES, the various embodiments disclosed herein relate to systems, apparatuses, and methods for utilizing an electric motive device, such as an electric motor, motor-generator, and the like, to supplement power during cylinder deactivation and cylinder reactivation when a vehicle receives a request (e.g., accelerator pedal input, brake pedal input, etc.) for an increase or a decrease in power output. Utilizing the electric motive device to supplement power during cylinder deactivation and cylinder reactivation may decrease certain emissions, such as NOx spikes and particulate matter (PM) spikes. Cylinder deactivation (CDA) mode is a broad term that encompasses various related but distinct cylinder deactivation operating modes. A first type of CDA operating mode is known as “fixed cylinder CDA.” In fixed cylinder CDA operating mode, the same cylinder(s) are active/inactive each engine cycle during the fixed cylinder CDA operating mode. A second type of CDA operating mode is known as “skip-fire” operating mode. In skip-fire CDA mode, one or more cylinders are deactivated/inactive (e.g., combustion does not occur) on a cycle-by-cycle basis. Accordingly, a cylinder may be inactive for a first engine cycle and active for a second engine cycle. An “active” cylinder means that combustion is allowed to occur in that cylinder. An “inactive” or “deactivated” cylinder means that combustion is not allowed to occur in that cylinder. The present disclosure is applicable with each type of CDA operating mode, and the term CDA mode is meant to encompass all such operating modes unless indicated otherwise. In operation and at the conclusion of CDA operating mode, reactivating one or more cylinders can lead to unwanted exhaust gas emissions due to the contents of the one or more cylinders upon reactivation. For example, a deactivated cylinder may have an undesired ratio of cylinder contents (e.g., air, fuel, recirculated exhaust gas, etc.) when commanded for combustion (reactivation) that may result in NOx spikes and PM spikes (i.e., NOx or PM emissions above a predefined threshold). Wherein the predefined NOx spikes and PM spikes may adversely result in a difficulty in complying with various emissions regulations. As described herein, a controller commands an electric motive device to provide or supplement the power provided by the engine system to accommodate the request for increased power during reactivation, such that the deactivated cylinder(s) is not immediately reactivated (i.e., reactivation of the one or more inactive cylinders is time delayed). In operation and when a reactivation command is received, the controller may open an exhaust valve of the deactivated cylinder(s) to allow at least some of the contents of the cylinder to be exhaled to an exhaust gas conduit. As another example, the controller may determine or estimate the contents of the deactivated cylinder(s). In each situation, the controller may then determine a desired charge for the cylinder(s) for reactivation (e.g., intake air and/or intake air and fuel) to enable a desired combustion condition (e.g., rich, lean, stoichiometric). During this time, the controller may command the electric motive device to provide the additional power requested by the operator while the contents of the to-be-activated cylinder(s) are adjusted such that power requirements for the vehicle are met or likely met. When the contents of the to-be-activated cylinder(s) meet or likely meet a desired composition (i.e., mixture), combustion is enabled in the to-be-activated cylinder(s) by the controller. In some embodiments, the contents may include a desired charge composition and/or the cylinder having a pressure at or above a predefined pressure threshold. Information regarding the contents of the cylinder may be determined by a plurality of sensors that directly measure the contents of the cylinder, or may be estimated based on sensors located proximate the cylinders (e.g., upstream and/or downstream of the cylinders). In some embodiments and as described herein, the electric motive device may be utilized during cylinder deactivation, such as when the engine system receives a request for decreased power. With respect to deactivation or reactivation, the controller may command the electric motive device to supplement engine power while one or more cylinders are cycled until the one or more cylinders have the desired cylinder contents. Without waiting for a desired composition of the contents of the cylinders (which may be a balance with the current active cylinders), the currently commanded charge (e.g., air, fuel injection, etc.) may not result in a complete or near complete combustion of the to-be-activated cylinders. For example, during CDA, the contents of deactivated cylinders may decrease in temperature, congregate in unwanted portions of the cylinder, and so on, all of which may lead to incomplete or nearly incomplete combustion characteristics. As a result, increased amounts of NOX, PM, and other undesired exhaust gas emissions characteristics may occur. However, by waiting to cause combustion when the contents are at a desired composition, these emissions “spikes” may be mitigated. As used herein, the phrases “typical operating pattern” or “normal operating pattern” as used with respect to describing operation of valves refers to standard valve timing in an internal combustion engine. For example, during an intake stroke, the intake valve is open to allow for the cylinder to draw in contents and the exhaust valve is closed to prevent the same contents or trapped contents from escaping and to prevent drawing in exhaust gas. A valve operating “outside of the typical operating pattern” refers to a valve being open or closed outside of standard valve timing. For example, an exhaust valve would be operating outside of the typical operating pattern if it were open during an intake stroke of a cylinder. As used herein, the term “cycling” or “cycle” as used with respect to describing operation of a deactivated cylinder (i.e., cycling a cylinder) refers to operating the engine and particularly the cylinder without combustion (e.g., no spark ignition or compression ignition) through a full set of repeatable operations for the deactivated cylinder (e.g., a single occurrence of each stroke of the cylinder). Operation of the deactivated cylinder may include an exhaust stroke, wherein the contents of the cylinder are evacuated through an open exhaust valve by a piston pushing out the cylinder contents, and an intake stroke, where the piston pulls in contents through an open intake valve. Power and compression strokes may also occur. However and as used herein, the cycle of a deactivated cylinder refers to a cylinder experiencing an exhaust and an intake stroke and any other strokes without combustion occurring. Thus, power and compression strokes may occur during the cycle, but combustion is prevented while the cylinder is deactivated (e.g., no fuel injection during compression in a compression-ignition engine, no spark in a spark-ignited engine). Accordingly and for a four-stroke engine, a cycle of a deactivated cylinder includes the four-strokes occurring in the cylinder but combustion not happening. The cycle may be different for different engine types (e.g., a four-stroke engine cycle may differ from a two-stroke engine cycle). The controller as described herein may count/track the number of cycles of the deactivated cylinder. In some embodiments, cycling a cylinder may include operating an intake valve and/or an exhaust valve of the deactivated cylinder according to a typical operating pattern (e.g., intake valve is open and exhaust valve is closed during intake stroke, etc.). Alternatively, cycling a cylinder may include a controller commanding a valve actuation system, both described herein, to operate the intake valve and/or the exhaust valve of the deactivated cylinder outside of typical operating patterns (e.g., intake valve is open during exhaust stroke, etc.). Referring now toFIG.1, a schematic diagram of a vehicle with a system100is shown, according to an exemplary embodiment. The system100may be included in an on-road or an off-road vehicle including, but not limited to, line-haul trucks, mid-range trucks (e.g., pick-up trucks), tanks, airplanes, locomotives, various types of industrial equipment (excavators, backhoes, tractors, mowers, etc.), etc. The system100could also be a part of a stationary system (e.g., generator, certain factory machinery, etc.). The system100includes an engine system102having an engine103with at least one cylinder104, at least one valve106, and at least one camshaft108, at least one sensor110, a drivetrain112coupled to the engine system102, an electric motive device114coupled to the drivetrain112, a battery116coupled to the electric motive device114, an input device120, a valve actuation system122, and a controller118coupled to each of the aforementioned components/systems. It should be understood that the vehicle may include additional components/systems than those depicted and described herein. In some embodiments, the engine103is a compression engine (e.g., engine operating on the diesel cycle) using fuel configured for compression engines (e.g., diesel fuel, bio-diesel, etc.). In some other embodiments, the engine103is a spark-ignition engine (e.g., engine employing a spark plug to produce ignition) using fuel configured for spark-ignition engines (e.g., gasoline, etc.). In various alternate embodiments, the engine103may have other structures or be a part of other engine systems. For example, the engine103may be a hybrid engine, which may include both an electric motor or motor(s) and an internal combustion engine that function to provide power to propel the vehicle. A hybrid vehicle can have various configurations. For example, in a parallel configuration, both the electric motor and the internal combustion engine are operably connected to the drivetrain112to propel the vehicle. In a series configuration, the electric motor is operably connected to the drivetrain112and the internal combustion engine indirectly powers the drivetrain112by powering the electric motor (examples include extended range electric vehicles or range-extended electric vehicles). In the example depicted, the engine103is a compression-ignition powered by diesel fuel. The system100may also include an exhaust aftertreatment system. The exhaust aftertreatment system may be coupled to the engine103and structured to treat exhaust gases from the engine103in order to reduce the emissions of harmful or potentially harmful elements (e.g., NOXemissions, CO emissions, PM emissions, etc.). The aftertreatment system may include various components and system, such as a particulate filter and a selective catalytic reduction (SCR) system. A selective catalytic reduction system can convert nitrogen oxides present in the exhaust gases produced by the engine into diatomic nitrogen and water through oxidation within a catalyst. A particulate filter may be configured to remove particulate matter, such as soot, from exhaust gas flowing in an exhaust gas conduit system. The SCR catalyst operation can be affected by several factors. For example, the effectiveness of the SCR catalyst to reduce the NOXin the exhaust gas can be affected by the operating temperature. If the temperature of the SCR catalyst is below a threshold value or range, the effectiveness of the SCR catalyst in reducing NOXmay be reduced below a desired threshold level, thereby increasing the risk of high NOXemissions into the environment. The SCR catalyst temperature can be below the threshold temperature under several conditions, such as, for example, during and immediately after engine startup, during cold environmental conditions, etc. Further, typically, higher combustion temperatures promote engine out NOX(EONOX) production. This is due to the rapid fire expansion from within the cylinder, which leads to the release of NOX. Increasing EGR leads to reduction in combustion temperatures, which reduces EONOX. However, EGR can promote particulate matter emissions due to incomplete combustion of particles. Additionally, higher loads and power demands also tend to increase combustion temperatures and, in turn, EONOX. Higher power output coincides with higher fueling pressures and quantity (increases in fuel rail pressure). In turn, increasing fueling pressures, quantity, etc. also tends to promote EONOXproduction. The aftertreatment system may further include a reductant delivery system which may utilize a decomposition chamber (e.g., decomposition reactor, reactor pipe, decomposition tube, reactor tube, etc.) to convert the reductant (e.g., urea, diesel exhaust fluid (DEF), Adblue®, a urea water solution (UWS), an aqueous urea solution, etc.) into ammonia. Reductant is added to the exhaust gas stream to aid in the catalytic reduction. The reductant may be injected by an injector upstream of the SCR catalyst member such that the SCR catalyst member receives a mixture of the reductant and exhaust gas. The reductant droplets undergo the processes of evaporation, thermolysis, and hydrolysis to form non-NOxemissions (e.g., gaseous ammonia, etc.) within the decomposition chamber, the SCR catalyst member, and/or the exhaust gas conduit system, which leaves the aftertreatment system. The aftertreatment system may further include an oxidation catalyst (DOC) fluidly coupled to the exhaust gas conduit system to oxidize hydrocarbons and carbon monoxide in the exhaust gas. In order to properly assist in this reduction, the DOC may be required to be at a certain operating temperature. In some embodiments, this certain operating temperature is between approximately 200 degrees C. and 500 degrees C. In other embodiments, the certain operating temperature is the temperature at which the conversion efficiency of the DOC exceeds a predefined threshold value. The aftertreatment system may further include a Lean NOx Trap (LNT) and/or a three-way catalyst (TWC) (or another catalytic converter). The LNT may act to reduce NOx emissions from a lean burn internal combustion engine by means of adsorption. Among other potential functions and features, the TWC may function to manage emissions from rich-burn engines while providing optimal performance with minimal cleaning or maintenance. Utilizing a flow-through substrate coated with a precious metal catalyst, the chemical oxidation process may convert engine out emissions into harmless nitrogen, carbon dioxide and water vapor as the gas passes through the catalytic converter (e.g., three-way catalyst). The engine103includes a plurality of cylinders104. The size/displacement of the engine103may vary based on application (e.g., 1 L to 120 L, etc.). The orientation of the cylinders104may vary based on structure of the engine103as well (e.g., V6-style engine, V8, include, etc.). Further, there may be any number of cylinders104arranged in any engine orientation (e.g., in a V-shape, in a W-shape, inline, etc.). For example, there may be six cylinders104oriented in a V-configuration (e.g., two rows of three cylinders104). In some embodiments, such as when the engine103is a spark-ignition engine, the engine103may include a spark plug. The spark plug may be a device capable for ignition the contents of the combustion chamber (e.g., electric current spark ignition plug, flame igniters, etc.). During CDA mode, the spark plug may be deactivated in the cylinders that are deactivated. The engine system102further includes valves106that are coupled to the engine103. The valves106are configured to facilitate an intake of air or a charge into the cylinders104and an exhaust of exhaust gases from the cylinders104. Each cylinder104includes at least two valves106, an intake valve and an exhaust valve. Opening the intake valve enables the associated cylinder104to be in fluid communication with an engine's intake system (e.g., carburetor, fuel injector, etc.). The intake valve facilitates the input of constituents required for combustion (e.g., fuel, oxidant, etc.). For example, the intake valve allows air, recirculated exhaust gas, and fuel into the combustion chamber. Opening the exhaust valve enables the associated cylinder104to be in fluid communication with the engine exhaust aftertreatment system (e.g., filters, catalytic converter, exhaust recirculation system, etc.). The exhaust valve facilitates output of at least a portion of contained cylinder contents. The exhaust valve may exhaust cylinder contents after combustion, or may exhaust cylinder contents prior to combustion. In some embodiments and in the example shown as described above where the engine103is a compression-ignition engine, the cylinder104includes a fuel injector configured to inject fuel directly into the combustion chamber. As described herein, the controller118may selectively open, partially open, and/or close the intake and/or exhaust valves in order to refresh the contents of the deactivated cylinder until the contents are within a desired tolerance or range (e.g., by monitoring an intake air amount and/or EGR amount to the cylinder while the intake valve is open and allowing some contents to escape via opening of the exhaust valve until the intake air and/or EGR amount are within a desired range). The engine system includes a camshaft108coupled to the engine103. In particular, the camshaft108is operably coupled to the valves106. The engine system may include a plurality of camshafts108, in some embodiments. For example, when the cylinders104are oriented in a V-configuration (e.g., two rows of cylinders104), the engine system102may include a camshaft108on each row of cylinders104. In some embodiments, the plurality of camshafts108may be configured to independently control different portions of a system100. The camshaft108includes a plurality of cams (not shown), each cam corresponding to a valve106. When the camshaft108rotates, the cams open and close the corresponding valves106. In some embodiments, the valves106may include a device configured to keep the valve106in an open position or a closed position, regardless of the camshaft108position. During CDA mode (such as a dynamic skip fire operating mode), the valves106associated with one or more of the cylinders104are commanded (by the controller118) into a closed position. As a result, intake and exhaust is prevented or substantially prevented from those one or more cylinders (i.e., the one or more cylinders are deactivated). As described herein, the controller118may monitor operation of the system100via one or more sensors110. The sensors110are configured to detect operation characteristics (e.g., temperature, pressure, contents, etc.) of certain components ofFIG.1, such as the cylinder104, the valve106, the drivetrain112, the electric motive device114, and so on. The number, placement, and type of sensors included in the system100is highly configurable. The sensors110may include, but are not limited to, one or more of an oxygen sensor, NOXsensor, PM sensor, mass-air-flow sensor, intake manifold sensor, exhaust manifold pressure sensor, a fluid sensor (e.g., exhaust gas flow rate, coolant flow rate, etc.), a pressure sensor (e.g., tire pressure, cylinder pressure, etc.), and so on. The sensors110may be located within or proximate to one or more cylinders of the cylinders104. In some embodiments, only certain cylinders104may include a sensor110. In some embodiments, the sensors110may be included in intake and exhaust channels leading to and away from the cylinders104, respectively. Accordingly, one or more sensors110may be configured to detect or otherwise acquire information regarding a makeup of the contents of the cylinder104. For example, an oxygen sensor may be disposed upstream of the cylinder and configured to determine an oxygen content of charge air entering the cylinder104. Based on the fuel injected for the cylinder, the controller118may determine or estimate an air-to-fuel ratio for the cylinder (or, an oxygen content based on the readings/data/information from the oxygen sensor). As another example, a mass flow sensor may be disposed upstream of the cylinder and configured to determine a flow rate of exhaust gas into the cylinder104. Based on the flow rate over a predefined unit of time, the controller118may determine an amount of EGR provided to the cylinder for a period of time (via an integration process using the flow rate over a predefined amount of time). A pressure sensor may be disposed proximate to one or more fuel injectors and configured to acquire information regarding a fuel pressure (or, with systems with a common rail, a pressure of the common rail). Thus, the one or more of the sensors110may be located upstream (e.g., in the intake) and/or downstream (e.g., in the exhaust) of the cylinder104. In some embodiments, a cylinder104may include a plurality of sensors110each configured to detect different contents of the cylinder104. In some embodiments, each individual sensor110is configured detect multiple types of cylinder contents. In some embodiments, the sensors110directly measure the contents of the cylinder104. For example, a sensor110may be configured in the cylinder104to measure the makeup of the charge within the cylinder104. While the description is primarily directed to a single cylinder104herein, it should be understood that the principles and features may be applied across some or all of the cylinders of the engine. Cylinder104contents may be determined by the controller118after receiving signals, information, data, etc. from the at least one sensor110. The controller118may compare the sensor110signals to a lookup table stored in a memory of the controller118. For example, a sensor110may detect a specific temperature of intake air, and in response, the controller118may then compare the temperature as detected by the sensor110and determine the density of the air corresponding to that temperature. The controller118may also use one or more algorithms, formulas, models, etc. to determine the cylinder contents. For example, to determine an EGR fraction, the controller118may receive signals from one or more sensors110that detect mass-flow-rate of intake air and mass-flow-rate of intake EGR into the cylinder104for a period immediately preceding the cylinder104deactivation (e.g., the cycle before the cylinder104was deactivated). The controller118may then use an algorithm to calculate the EGR fraction estimated to be trapped/stored in the cylinder104during deactivation based on these flow rates. The sensors110may also include sensors to detect information regarding emitted exhaust gas from the engine103. The sensors may be NOx sensors, temperature sensors, particulate matter (PM) sensors, and/or other emissions-related sensors. The NOx sensors are structured to acquire data indicative of a NOx amount at each location that the NOx sensor is located (e.g., a concentration amount, such as parts per million). The NOx sensor may also measure or acquire data indicative of an oxygen concentration in the exhaust gas flowing by the sensor. The temperature sensors are structured to acquire data indicative of a temperature at their locations. The PM sensors are structured to monitor particulate matter flowing through the aftertreatment system. In one embodiment, the sensors are structured as exhaust gas constituent sensors (e.g., CO, NOx, PM, SOx, etc. sensors). In another embodiment, certain of the sensors110are structured as non-exhaust gas constituent sensors that are used to estimate exhaust gas emissions (e.g., temperature, flow rate, etc.). Additional sensors may be also included with the vehicle. The sensors may include engine-related sensors (e.g., torque sensors, speed sensors, pressure sensors, flow rate sensors, temperature sensors, etc.). The sensors may further include electric motive device-related sensors (e.g., a battery state of charge (SOC) sensor, a power output sensor, a voltage sensor, a current sensor, etc.). The additional sensors may still further include sensors associated with other components of the vehicle (e.g., speed sensor of a turbo charger, fuel quantity and injection rate sensor, fuel rail pressure sensor, etc.). The sensors may be real or virtual (i.e., a non-physical sensor that is structured as program logic in the controller118that makes various estimations or determinations based on received data). For example, an engine speed sensor may be a real or virtual sensor arranged to measure or otherwise acquire data, values, or information indicative of a speed of the engine103(typically expressed in revolutions-per-minute). The sensor is coupled to the engine (when structured as a real sensor), and is structured to send a signal to the controller118indicative of the speed of the engine103. When structured as a virtual sensor, at least one input may be used by the controller118in an algorithm, model, look-up table, etc. to determine or estimate a parameter of the engine (e.g., power output, etc.). The other sensors may be real or virtual as well. As described herein, the sensors110and additional sensors may provide data regarding how the particular vehicle system is operating, and determine how to adjust operating points of the engine and/or motor/generator based on the sensor feedback. The system100includes a drivetrain112. The drivetrain112is coupled to the engine103. The drivetrain112may include a transmission coupled to the engine103, a final drive coupled to the transmission, and any other components of a drivetrain. When combustion occurs within the cylinders104, the drivetrain112receives the energy released by the combustion (in the form of a rotating crankshaft) and converts the rotating crankshaft into mechanical energy for rotating a driveshaft (not shown). The drivetrain112provides the final drive power to an end component/system (e.g., power the wheels, another motive device, such as tracks, or a power receiving device if, for example, embodied in a stationary piece of equipment such as a generator or genset). In the example shown, the system100is included in a vehicle such that power is provided to wheels to move the vehicle. The drivetrain112may include sensors (virtual or real) that provide information or data regarding operation of the drivetrain112. For example, the sensors110may provide the rotational speed of the wheels. The system100includes an electric motive device114(also referred to as an electric machine herein). The electric motive device114is operably coupled to the drivetrain112. The electric motive device114may be an electric motor, a motor-generator, an alternator, or another electric power device. The electric motive device114includes a motor portion configured to produce mechanical energy. In some embodiments, such as when the electric motive device114is a motor-generator, the electric motive device114includes a distinct motor and a distinct generator, coupled together. The motor coils of the distinct motor and generator coils of the distinct generator may be wound around a single rotor, or may be wound around separate rotors. The electric motive device114is electrically coupled to a battery116. The battery116is a power source (e.g., lead-acid, Li-Ion, Li-Po, etc.) configured to provide the electric motive device114with electrical power. In some embodiments, the battery116is the main vehicle battery (e.g., used for starting the engine, used for operating certain vehicle systems/components when the engine is not operating, etc.). In some embodiments, such as when the electric motive device114includes a generator portion, the generator portion of the electric motive device114may be configured to provide the battery116with electric power, which the battery116may then store. The electric motive device114converts the electrical power provided by the battery116into mechanical energy (e.g., rotational energy) in the drivetrain112, providing the drivetrain112with supplemental power. It should be understood that other power providing devices for the electric motive device114are contemplated herein (e.g., ultra-capacitors, etc.). In the example shown, the electric motive device114is coupled to the drivetrain112and selectively drives or rotates the driveshaft to, for example, propel the vehicle embodying the system100. The electric motive device114may be operated at various levels and loads/power outputs (e.g., 0%, 10%, 20%, 50%, 70%, 100%, etc.) of the maximum rated load of the electric motive device114. As also shown, an input device120is included in the system100. The input device120is coupled to the controller118, and in turn, may exchange signals, information, etc. with the controller118. For example, the input device120may provide an indication regarding a change in power requested from the system100. The input device120may be vehicle control devices, such as an accelerator pedal, a transmission shifter, a brake pedal, transmission paddle shifter, etc. The input device120may also be a circuit configured to send power requirement signals to the controller118. The input device120may include a steering wheel, a joystick, a brake pedal, an accelerator pedal, etc. For example, when the accelerator pedal is pressed, the controller118may interpret this position as a request for an increase in power. A valve actuation system122is included in the system100. The valve actuation system is coupled to the controller118. The valve actuation system122also coupled to the camshaft108. The valve actuation system122is configured to rotate the camshaft108responsive to signals, commands, etc. from the controller118. The valve actuation system122may be coupled directly to the valves106, such that the valves may be operated (opened or closed) without the camshaft108. In some embodiments, the valve actuation system122, based on one or more commands or instructions from the controller118, may operate the intake valve and/or exhaust valve of at least one cylinder104outside of a typical operating pattern (e.g., the intake valve is open during the exhaust stroke of the cylinder104). As also shown, the system100includes a controller118. The controller118is structured to control, or at least partly, operation of the electric motive device114and the valve actuation system122, the sensors110, engine103, and the input device120. Communication between and among the components may be via any number of wired and/or wireless connections. For example, a wired connection may include a serial cable, a fiber optic cable, a CAT5 cable, or any other form of fired connection. A wireless connection may include the Internet, Wi-Fi, cellular, radio, etc. In one embodiment, a controller area network (“CAN”) bus provides the exchange of signals, information, and/or data. The CAN bus includes any number of wired and wireless connections that provide the exchange of signals, information, and/or data. The CAN bus may include a local area network (LAN), or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). Thus, the controller118may receive and use various data, where the data may include EGR fraction data (e.g., EGR fraction or estimated amount within at least one cylinder104), air-to-fuel ratio data (e.g., air-to-fuel ratio or estimated ratio within at least one cylinder104), temperature data (e.g., temperature inside an intake channel leading to at least one cylinder104, an estimated temperature within at least one cylinder104), vehicle operating data (e.g., accelerator pedal position, brake pedal position, transmission setting, a requested torque, an engine speed, vehicle speed, engine temperature, etc.), and so one where the data may receive via one or more sensors110and/or determined by the controller118based on information received from the sensors, and so on. The structure and function of the controller118are further described in regard toFIG.2 Referring now toFIG.2, a schematic diagram of the controller118ofFIG.1is shown, according to an exemplary embodiment. The controller118is structured to receive inputs (e.g., signals, information, data, etc.) from one or more components of system100, such as the sensors110or the input device120. The controller118is also structured to send commands, instructions, etc. to one or more components of the system100. Thus, the controller118is structured to control, at least partly, the electric motive device114, the engine103, and the valve actuation system122. As the components of theFIG.2can be embodied in a vehicle, the controller118may be structured as one or more electronic control units (ECU). The controller may be separate from or included with at least one of a transmission control unit, an exhaust aftertreatment control unit, a powertrain control module, and engine control module, etc. In operation, the controller118is configured to determine activate/deactivate the electric motive device and operate the electric motive device114to supplement an engine power output during cylinder deactivation or reactivation as part of the CDA mode to prevent or reduce certain undesired emissions characteristics (e.g., NOx spikes and PM spikes). Utilization of the electric motive device114allows a supplemental amount of power to be provided to, for example, the drivetrain112until one or more of the deactivated cylinders104are reactivated to minimize NOx spikes and without PM spikes. In operation and as described herein, when the controller118receives an input, such as a power request, from the input device120, the controller118then determines the supplemental power required or likely required by the electric motive device114to fulfill the power request relative to a current power output from the engine103. The controller118may analyze data from a sensor110to determine the cylinder contents of one or more deactivated cylinders104. The controller118may compare the cylinder contents to a predefined threshold and, particularly, a predefined tolerance or range regarding the contents of the cylinder for reactivation. If the cylinder contents of the cylinder104are outside the tolerance or range, the controller118sends a signal to the valve actuation system122to cycle the cylinders104, without commanding combustion, until the contents of the cylinder104are within the predefined tolerance or range amounts. In some embodiments, the valve actuation system122cycles the cylinders104according to a typical operating pattern. Alternatively, the controller118commands the valve actuation system122to operate the valves106of the cylinder104outside of the typical operating pattern during cylinder104to refresh the contents of the cylinder to reach or obtain a predefined tolerance or range amount of certain cylinder contents faster than when the valves106operate according to the typical operating pattern. If the cylinder contents are within the predefined tolerance or range amounts, then the controller118reactivates the one or more cylinders104(i.e., causes combustion to occur in these cylinders). In some embodiments, each cylinder104is reactivated independently of the other cylinders104. The controller118is shown to include a processing circuit200having a processor202and a memory device204, a CDA control system206having an input circuit208, a control circuit210, and an output circuit212, and a communications interface214. The communications interface214is structured to enable the controller118to communicate with system100components such as the electric motive device114, the sensors110, the valve actuation system122, and the input device120. The communications interface214may include any combination of wired and/or wireless interfaces (e.g., jacks, antennas, transmitters, receivers, transceivers, wire terminals, etc.) for conducting data communications with these various systems, devices, or networks to enable in-vehicle communications (e.g., between and among the components of the vehicle) and, in some embodiments, out-of-vehicle communications (e.g., with a remote server). For example and regarding out-of-vehicle/system communications, the communications interface214may include an Ethernet card and port for sending and receiving data via an Ethernet-based communications network and/or a Wi-Fi transceiver for communicating via a wireless communications network. In some embodiments, a telematics device may be included with the vehicle that enables out-of-vehicle communications. The communications interface214may be structured to communicate via local area networks or wide area networks (e.g., the Internet) and may use a variety of communications protocols (e.g., IP, LON, Bluetooth, ZigBee, radio, cellular, near field communication). In one configuration, the input circuit208, the control circuit210, and the output circuit212are embodied as machine or computer-readable media storing instructions that are executable by a processor, such as processor202and stored in a memory device, such as memory device204. As described herein and amongst other uses, the machine-readable media facilitates performance of certain operations to enable reception and transmission of data. For example, the machine-readable media may provide an instruction (e.g., command, etc.) to, e.g., acquire data. In this regard, the machine-readable media may include programmable logic that defines the frequency of acquisition of the data (or, transmission of the data). The computer readable media may include code, which may be written in any programming language including, but not limited to, Java or the like and any conventional procedural programming language, such as the “C” programming language or similar programming languages. The computer readable program code may be executed on one processor or multiple remote processors. In the latter scenario, the remote processors may be connected to each other through any type of network (e.g., CAN bus, etc.). In another configuration, the input circuit208, the control circuit210, and the output circuit212are embodied as hardware units, such as electronic control units. As such, the input circuit208, the control circuit210, and the output circuit212may be embodied as one or more circuitry components including, but not limited to, processing circuitry, network interfaces, peripheral devices, input devices, output device, sensors, etc. In some embodiments, the input circuit208, the control circuit210, and the output circuit212may take the form of one or more analog circuit, electronic circuit (e.g., integrated circuits (IC), discrete circuits, system on a chip (SOCs) circuits, microcontrollers, etc.), telecommunication circuits, hybrid circuits, and any other type of “circuit.” In this regard, the input circuit208, the control circuit210, and the output circuit212may include any type of component for accomplishing or facilitating achievement of the operations described herein. For example, a circuit as described herein may include one or more transistors, logic gates (e.g., NAND, AND, NOR, OR, XOR, NOT, XNOR, etc.), resistors, multiplexers, registers, capacitors, inductors, diodes, wiring, and so on. The input circuit208, the control circuit210, and the output circuit212may also include programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like. The input circuit208, the control circuit210, and the output circuit212may include one or more memory device for storing instructions that are executable by the processor(s) of the input circuit208, the control circuit210, and the output circuit212. The one or more memory device and processor(s) may have the same definition as provided below with respect to memory device204and processor202. In some hardware unit configurations, the input circuit208, the control circuit210, and the output circuit212may be geographically dispersed throughout separate locations in, for example, a vehicle. Alternatively and as shown, the input circuit208, the control circuit210, and the output circuit212may be embodied in or within a single unit/housing, which is shown as the controller118. In the example shown, the controller118includes the processing circuit200having the processor202and the memory device204. The processing circuit200may be structured or configured to execute or implement the instructions, commands, and/or control processes described herein with respect to the input circuit208, the control circuit210, and the output circuit212. The depicted configuration represents the input circuit208, the control circuit210, and the output circuit212as machine or computer-readable media storing instructions that may be stored by the memory device. However, as mentioned above, this illustration is not meant to be limiting as the present disclosure contemplates other embodiments where the input circuit208, the control circuit210, and the output circuit212, or at least one circuit of the input circuit208, the control circuit210, and the output circuit212, is configured as a hardware unit. All such combinations and variations are intended to fall within the scope of the present disclosure. The processor202may be a single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, and the like. In this regard, a processor may be a microprocessor, or, any conventional processor, or state machine. A processor also may be implemented as a combination of computer devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some embodiments, the processor202may be shared by multiple circuits (e.g., the input circuit208, the control circuit210, and the output circuit212may comprise or otherwise share the same processor that, in some example embodiments, may execute instructions stored, or otherwise accessed, via different areas of memory). Alternatively or additionally, the one or more processors may be structure to perform or otherwise execute certain operations independent of one or more coprocessors. In other example embodiments, two or more processors may be coupled via a bus to enable independent, parallel, pipelined, or multi-threaded instruction execution. All such variations are intended to fall within the scope of the present disclosure. The memory device204(e.g., memory, memory unit, storage device) may include one or more devices (e.g., RAM, ROM, Flash memory, hard disk storage) for storing data and/or computer code for completing or facilitating the various processes, layers and modules described in the present disclosure. The memory device204may be coupled to the processor202to provide computer code or instructions to the processor202for executing at least some of the processes described herein. Moreover, the memory device204may be or include tangible, non-transient volatile memory or non-volatile memory. Accordingly, the memory device204may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described herein. The CDA control system206is structured to receive information from the sensors110through the input circuit208. In particular, the input circuit208is structured to receive information from the sensors110via the communications interface214. The input circuit208may also receive data (e.g., power request commands) from the input device120(e.g., depression of the accelerator pedal, release of the accelerator pedal, indications of transmission shift events, etc.). The input circuit208may modify or format the received information (e.g., via an analog/digital converter, etc.) so that the information can be readily used by the control circuit210or another circuit (e.g., the output circuit212). Based on the received information, the control circuit210of the CDA control system206is structured to monitor the system100and determine one or more control operating parameters for the electric motive device114, engine103, valve actuation system122, and various other components or systems. The output circuit212is structured to send the control operating parameters to the electric motive device114and the valve actuation system122. The output circuit212may modify or format the information prior to sending (e.g., via an analog/digital converter, etc.) so that information can be readily used by the electric motive device114and the valve actuation system (and/or other systems, components, etc.). The CDA control system206is structured to implement a CDA operating mode with the engine. The CDA control system206is configured to control activation and deactivation of the cylinders104of the engine103. The CDA control system206is also structured to implement various CDA operating modes, such as dynamic skip-fire operating mode. The CDA control system206may also determine the power provided by the active cylinders104to the drivetrain112during the CDA operating mode. For example, a sensor110may monitor the power output and send the power output data to the controller118. As another example, the CDA control system206may correlate fueling commands (e.g., quantity, timing, etc.) to an approximate power output for the engine (i.e., the active cylinders). Based on received information, the CDA control system206may determine a maximum or approximate maximum power output that the number of activated cylinders104can produce without activation of additional cylinders. The maximum power output may be a predefined value that is specific to the number of active cylinders and potentially other factors. For example, the CDA control system206may determine that four of six cylinders104are active in an engine103and, as such, the CDA control system206may then determine that the engine103may produce Y HP maximum power corresponding to four active cylinders. In another embodiment, the CDA control system206may determine a maximum power output for the number of active cylinders by the control circuit210accessing a lookup-table, using an algorithm, a model, etc. The operating mode as well as any associated information (e.g., power output, maximum power output, etc.) may be stored and accessed in the memory device204. The CDA control system206is structured to receive a power request from the input device120. The control circuit210compares the power request to the current power output of the engine103to determine how much supplemental power is needed. For example, if the current power output is 10 units of power and the power request is for approximately 13 units of power, the control circuit210determines that 3 units of power are needed. The control circuit210determines if the current number of activated cylinders can provide the supplemental power, such as when the power request is at or below the maximum power threshold, or if the electric motive device114can provide the supplemental power. If the control circuit210determines the electric motive device114can provide the supplemental power, the CDA control system206is structured to send a command (e.g., an electric signal) to the electric motive device114. In one embodiment, the electric motive device114is deactivate so the control circuit210activates the electric motive device114. In another embodiment, the electric motive device114is already active so the control circuit210commands the electric motive device114to the requested supplemental power. The output circuit212of the CDA control system206transmits the command to the electric motive device114to provide the supplemental power. For example, if the CDA control system206receives a power request above the maximum power output, the output circuit212sends a command to the electric motive device114to supplement the power of the engine103, the amount of supplemental power corresponding to the difference between the current power output and the power request. In some embodiments, the output circuit212may send a signal to the electric motive device114for the supplemental power to increase from zero, approximately zero, or another small amount to the desired amount over a period of time so to prevent sudden acceleration. The CDA control system206is also structured to send a command to the electric motive device114to deactivate or stop the electric motive device114when supplemental power is no longer needed, such as when the engine103provides sufficient power. The input circuit may receive information regarding the electric motive device114before and/or during activation, such as a battery state of charge, etc. If the battery state of charge is below a minimum threshold, the control circuit210may not command the supplemental power from the electric motive device114and instead activate one or more of the deactivated cylinders to meet the power demand. While the electric motive device114is providing the supplemental power, the CDA control system206is further structured to monitor cylinder contents via direct assessment and/or an estimation based on information received from the sensors110, which may include an oxygen sensor, a NOx sensor, PM sensor, mass-air-flow sensor, intake manifold sensor, exhaust manifold pressure sensor, and/or the like. The CDA control system206may receive direct measurements of cylinder contents from sensors110. For example, the control system may receive a direct measurement of the EGR fraction, the oxygen content, mass-air-flow, etc. within at least one cylinder104. The CDA control system206may be structured to receive sensor data that may be processed by the control circuit210to estimate the cylinder contents (e.g., EGR sensor that provides an indication of an EGR amount/fraction, oxygen/air amount via an air intake oxygen sensor, etc.). For example, the CDA control system206may receive sensor data from sensors110located upstream (e.g., in fuel lines, in air intakes, etc.) of the cylinders104. Based on the received sensor data, the control circuit210estimates (e.g., using a look-up table, using an algorithm, a model, etc.) the cylinder contents. More specifically and as an example, the CDA control system206may receive sensor data from a sensors110located in an air intake channel and in an exhaust intake channel. Based on the received data, the control circuit210determines the amount of air and exhaust that will be within at least one cylinder104and calculates the EGR fraction for the at least one cylinder104. The CDA control system206may also predict future cylinder contents by extrapolating information received from sensors110. For example, if the CDA control system206receives a number of measurements of air-to-fuel ratio over a period of time, the control circuit210may extrapolate (e.g., via a regression analysis) what the air-to-fuel ratio may be in the future. Once determined by the CDA control system206, the cylinder contents information may be stored and accessed in the memory device204. The CDA control system206may continuously monitor the cylinder contents or may monitor the cylinder contents periodically (e.g., every 1 s, every 2 s, every 3 s etc.). Based on the monitored cylinder contents, the CDA control system206is structured to determine when inactive cylinder104may be reactivated. To prevent NOXand PM spikes, cylinder contents are monitored until they are at a desired composition for reactivation. The desired contents may be predetermined ranges of cylinder contents based on operation of the engine (e.g., a current air-to-fuel ratio, a current EGR amount, etc.). Alternatively or additionally, the control circuit210determines the desired contents based on the situation (e.g., power request, temperature, speed, etc.). In some embodiments, the desired contents for reactivation may be an EGR fraction that is roughly equivalent across at least a subset of the cylinders104. The CDA control system206may determine when each cylinder104may be activated independently of the other cylinders104, or may determine when all of the cylinder104may be activated. Once the CDA control system206determines a cylinder104has a desired contents, the output circuit212sends a signal to the valve actuation system122to activate the corresponding cylinder104. For example, if the CDA control system206determines that the EGR fraction and the air-to-fuel ratio within the cylinder104are within a desired EGR fraction and air-to-fuel ratio range, the output circuit212sends a signal to the valve actuation system122to activate the corresponding cylinder104. If the cylinder contents are determined by the control circuit210to be undesired for reactivation, the output circuit212of the CDA control system206sends signals to the valve actuation system122to cycle the cylinders104. In some embodiments, the CDA control system206sends signals to the valve actuation system122to operate valves106in a typical operating pattern while cycling the cylinders104. During this time, the CDA control system206receives information regarding intake contents for the deactivated cylinder(s) (e.g., an air-to-fuel ratio, an oxygen value, an EGR value, etc. wherein the values are at an instant in time or over a predefined amount of time) and receives information regarding contents expelled to the exhaust manifold. Based on this information, the CDA control system206determines when the contents are at or approximately at a desired composition/mixture for reactivation. Alternatively, in some embodiments, the CDA control system206sends signals/commands to the valve actuation system122to operate valves106outside of a typical operating pattern while cycling the cylinders104, to reach desired cylinder contents faster than when using a typical operating pattern. In some embodiments, the output circuit212may command only the cylinders104with undesired contents to be refreshed (e.g., refresh the contents of the cylinder via opening and/or closing the intake and/or exhaust valves associated with those cylinders). In some embodiments, the output circuit212cycles the cylinders104a predefined number (e.g., 1, 2, 3, 4, 5, 6, etc.) of times. Further, at least one of the intake or exhaust valves may be open during the cycling so that the contents of the at least one deactivated cylinder are modified until a desired content composition is obtained (e.g., based on information from one or more sensors upstream and/or downstream of the cylinder, such as an oxygen content value, an EGR value, etc.). Once the control circuit210determines that the cylinder contents are desired for reactivation, the output circuit212commands the valve actuation system122to activate the at least one cylinder104with the desired contents. In some embodiments, the CDA control system206only activates cylinders104until the total number of active cylinders104are able to provide power at or above the power request. Referring generally toFIGS.3A-3C, various cylinder deactivation methods are shown, according to example embodiments. Cylinder deactivation includes closing the intake and exhaust valves of a cylinder, such as cylinders104, in an internal combustion engine. The intake and exhaust valves of the cylinder104are kept close until the cylinder104is reactivated. Movement of the valves is controlled by the valve actuation system122, which is controlled by the controller118. Thus, the controller118controls activation and deactivation of the cylinders104during CDA operating mode. Cylinder deactivation can trap different types of cylinder contents associated with different stages of combustion (e.g., intake, compression, exhaust, etc.) within the combustion chamber. The methods shown inFIGS.3A-3Crelate to a single cylinder104of the system100, but the methods may be applied to all of the cylinders104of the system100. Cylinders104of the system100may use different methods or may all use the same method. Furthermore, certain cylinders104may be at a different stage of a method, or all or some of the cylinders may be at the same stage of a method ofFIGS.3A-3C. Referring first toFIG.3A, a flow diagram of a method of vacuum trapping the contents of a cylinder104is shown, according to an example embodiment. The vacuum trapping method300is a method for emptying the contents of a cylinder104prior to deactivating the cylinder104. During the vacuum trapping method300, the intake valve of the cylinder104is closed. At process302, the remaining fuel in the cylinder104is combusted (e.g., via compression-ignition in the engine shown herein, via a spark in an SI engine, or other means in other applications). Combustion produces exhaust gases, which may include NOx and PM. At process304, the exhaust valve of the cylinder104is opened, allowing for the exhaust gas within the combustion chamber to be exhausted from the combustion chamber at process306. At process308, after at least a portion of the exhaust gases have been exhausted, the exhaust valve is closed. With the intake valve and the exhaust valve closed, additional contents are or are substantially prevented from entering the cylinder104. At process310, the cylinder104is deactivated, wherein the valves106of the cylinder104are closed or substantially closed until the cylinder104is reactivated. The resulting cylinder104is vacuum trapped, as the cylinder104does not contain any combustion gases or any other gases, e.g., a vacuum. The vacuum trapping method300may be repeated for each of a plurality of cylinders104independently, or the vacuum trapping method300may occur in each of a plurality of cylinders104simultaneously. Referring now toFIG.3B, a flow diagram of a method of hot trapping the contents of a cylinder104is shown, according to an example embodiment. The hot trapping method312is a method of capturing exhaust in a cylinder104and deactivating the cylinder104with the hot exhaust gas inside the cylinder. The exhaust valve is closed throughout the entirety of the hot trapping method312. The hot trapping method312begins with a desired charge for combustion inside the cylinder104. At process314, the intake valve is closed. Closing the intake and exhaust valves prevents or substantially prevents gases and particulate matter from entering or leaving the combustion chamber of the cylinder104. At process316, the contents of the cylinder104are combusted (e.g., via compression-ignition in the engine shown herein, via a spark in an SI engine, or other means in other applications). At process318, the cylinder104is deactivated with the relatively hot exhaust gas remaining in the combustion chamber of the cylinder104. Because of the presence of relatively hot exhaust gases being now trapped in the deactivated cylinder, this process is known as hot trapping. The valves106of the cylinder104are closed until the cylinder104is reactivated. The hot trapping method312may be repeated for each of a plurality of cylinders104independently, or the hot trapping method312may occur in each of a plurality of cylinders104simultaneously. Referring now toFIG.3C, a flow diagram of a method of cold trapping the contents of a cylinder104is shown, according to an example embodiment. In contrast to the hot trapping method described above, the cold trapping method320is a method of deactivating the cylinder104prior to combustion. At process322, the contents of the combustion chamber are combusted. The exhaust valve is then opened at process324, allowing for the exhaust gases and other matter produced during combustion to be exhausted through the exhaust valve. At process328, the exhaust valve is closed, while the intake valve is simultaneously opened at process330. At process332, the cylinder104takes in a desired charge for combustion. At process334, the cylinder104is monitored, by the controller118, for desired cylinder104contents. In some embodiments, the desired cylinder104contents may be a range of values for various constituents. Monitoring for desired contents may include monitoring the fraction of recirculated exhaust gas and the air-to-fuel ratio immediately prior to commanding the deactivation. Process334may be facilitated by at least one sensor110coupled to the controller118, or may be approximated by a computer configured to approximate the contents of a cylinder104. If the cylinder104is found to have undesired contents, the cold trapping method320returns to412to cycle the cylinder104. Process332and process334may be repeated until the contents of the cylinder104are desired for reactivation. In some embodiments, process334is omitted and process432is repeated a predetermined number of times before proceeding to process436. In some embodiments, process332is repeated a predetermined number of times. If the cylinder104is found to have the desired contents, then the method proceeds to process336. In some embodiments, process334may be omitted and the cold trapping method320may proceed directly to process336. At process336, the cylinder104is deactivated with the combustion gases remaining in the combustion chamber of the cylinder104, also known as cold trapping. The cold trapping method320may be repeated for at least one of the plurality of cylinders104independently, or the cold trapping method320may occur in each of the plurality of cylinder104simultaneously. In some embodiments, cold trapping method320is preferred over the vacuum trapping method300and the hot trapping method312, as the cold trapping method320can capture a predetermined amount of cylinder contents, such that when the cylinder104is reactivated, the system100can avoid NOx and PM spikes if the predetermined amount of cylinder contents is desired. Referring generally toFIGS.4-6, methods of utilizing an electric motive device (EMD), such as electric motive device114to provide supplemental power when a power request is received from an input device120by the controller118during a CDA operating mode are depicted, according to various example embodiments. Providing power from the electric motive device before reactivating one or more deactivated cylinders to meet, substantially meet, or attempt to meet the increased power demand from the operator may avoid transient undesired exhaust gas emissions characteristics (e.g., NOx and PM emissions above a predefined amount/threshold). In this regard, the one or more deactivated cylinders may have contents therein (e.g., particulate matter, oxygen, hydrocarbons, etc.) that may produce an undesired emission characteristic(s) when reactivated because the content mixture may not be tuned/calibrated for the present combustion conditions (e.g., a mixture of charge air, EGR, etc. to enable stoichiometric combustion or a desired rich or lean combustion). By delaying cylinder reactivation, the one or more deactivated cylinders are cycled by the controller118until a determined or estimated contents of the one or more deactivated cylinders may coincide with a desired mixture for combustion that alleviates potential exhaust gas emission spikes. Moreover, the additional power requirement may be met by the electric motive device. Accordingly, a realization of operability of the vehicle in combination with minimizing undesired transient emissions may be experienced. In some embodiments, the instructions to complete the methods described in reference toFIGS.4-6may be stored in the memory device204of the controller118. FIG.4is flow diagram of a method of supplementing power with an electric motive device, such as electric motive device114, according to an exemplary embodiment. The reactive activation method400includes utilizing an electric motive device114to supplement power (e.g., for the vehicle) after receiving a request for an increase in power output. At process402, the controller118commands the engine103to operate in a CDA operating mode. As mentioned above, the CDA operating mode may include a skip fire or dynamic skip fire operating mode, a fixed cylinder CDA operating mode, or another type of CDA operating mode. During the CDA operating mode, less than all of the cylinders104of the engine are active (i.e., a subset of the cylinders are deactivated). Accordingly, the system100can only produce a limited amount of power, as not all cylinders104are activate. At process404, a request for increased power is received. For example, the controller receives a signal from the input device120requesting additional power output above a current power output from the engine103. For example, an accelerator pedal may be depressed relatively further than the accelerator pedal was depressed for the past predefined amount of time. The power request may be based on a continual request (e.g., more than a predefined amount of time, such as two seconds) or be instantaneous. To determine the current power output, the controller118may determine an average power output for a past predefined amount of distance and/or time. The controller118may then add an upper threshold to this average. The upper threshold may correspond to the maximum power that the number of activated cylinders104of the system100may produce without reactivating any deactivated cylinders104. If the power request is greater than this threshold, the reactive activation method400may proceed. If the power request is below this threshold, the engine103is able to produce the desired power without activating any additional cylinders and does not require supplemental power. By employing this threshold, transient power fluctuations that may be caused by short grade situations may avoid triggering the reactive activation method400from proceeding. Thus, in this embodiment, the supplemental power request may typically cause reactivation of at least one deactivated cylinder. There may also be an analysis by the controller118of the battery116, facilitated by a sensor coupled to the battery116and the controller118. If the state of charge or other battery characteristic is above a threshold as determined by the controller118, then the controller118may direct the electric motive device114to draw power from the battery116. At process406, the controller118utilizes the electric motive device114to supplement power. At process406, the controller118may determine the power provided by the currently activated cylinders104of the system100and may command the electric motive device114to supplement the power provided by the currently activated cylinder104so that the drivetrain112may provide the power required by the request received at process404. In some embodiments, the controller118sends the electric motive device114instructions to deliver an amount of power corresponding to the number of deactivated cylinders104. For example, if one cylinder104is deactivated, the controller118commands the electric motive device114to provide a first amount of power. If two cylinders104are deactivated, the controller118commands the electric motive device114to provide a second amount of power, the second amount of power greater than the first amount of power. If three cylinders104are deactivated, the controller118commands the electric motive device114to provide a third amount of power, the third amount of power greater than the second amount of power. This may be extended to any number of deactivated cylinders104. At process408, the controller118monitors the contents of the cylinder104and compares the cylinder contents to a desired level for reactivation, as described in reference toFIG.2. In some embodiments, the valve actuation system122cold trapped the cylinders104, by following the cold trapping method320, such that the cylinders104have the desired cylinder contents prior to beginning the reactive activation method400and process408may be skipped. In some embodiments, the desired cylinder104contents may be a range of values specific to various cylinder constituents. For example, the controller118may receive signals from sensors110located proximate an air intake and fuel injector. The controller118may then determine the air-to-fuel ratio by extrapolating how much air and fuel would be within the cylinder104from the measurements taken by the sensors located in the air intake and the fuel injector. When determining the EGR fraction or amount, the controller118may, for example, receive signals from sensors110located in an exhaust intake and an air intake. The controller118may then calculate or determine the amount of exhaust and air in the cylinder104by extrapolating the reading from the sensors110. The controller118may determine the EGR fraction by determining a ratio of exhaust to air within the cylinder104. Once the cylinder contents are determined, the controller118compares the cylinder contents with a desired level to determine if the cylinder contents are as desired for activation. The desired level may be a predetermined range stored in the controller memory. The desired level may also be when the EGR fraction, or other cylinder contents parameter, are roughly equal across at least a subset of cylinders104. If the cylinder contents are determined to be undesired for activation, the controller118sends signals to the valve actuation system122to cycle the cylinder104at process410. The controller118may determine and send signals/commands/etc. corresponding to when the valve actuation system122should operate the valves106of the cylinder104during cycling (e.g., open, close, partially open the valves), outside of the typical operating pattern of the valves106. While the cylinder104is cycled at process410, the system100continues to utilize the electric motive device114. Process408and process410repeat until the cylinder104is determined to have the desired cylinder contents. Once the cylinder contents are determined to be desired for activation, the cylinder104is activated at process412. The activated cylinder104can then provide the drivetrain112with additional power. At process414, the controller118commands the electric motive device114to reduce the amount of power supplemented to drivetrain112by an amount equal to that of the additional power provided by the activated cylinder104. At process416, the controller118determines whether the engine103provides the requested power, independently of the electric motive device114. If the controller118determines the engine103provides the requested power, the electric motive device114is deactivated. If the controller118determines the engine103does not provide the requested power, the method returns to process408such that additional deactivated cylinder104may be activated. From process408, the process repeats until, at process416, the activated cylinders104are determined to provide the requested power and the electric motive device114is deactivated. Alternatively, the electric motive device114may continue to provide power. The reactive activation method400is repeated for each of the cylinders104independently or is repeated for each of the cylinders104simultaneously. At process418, the controller118sends signals to the electric motive device114to deactivate. In some embodiments, deactivation of the electric motive device114includes switching the electric motive device114from motor operation to generator operation. FIG.5is flow diagram of a repeating activation method500of supplementing power with an electric motive device, such as electric motive device114, according to another exemplary embodiment. The repeating activation method500includes utilizing an electric motive device114to supplement power in a drivetrain112after receiving a request for an increase in power. At process502, the engine103is operating in CDA operating mode, wherein a number of cylinders104are deactivated. During CDA mode, the engine103can only produce a limited amount of power, as not all cylinders104are activated. At process504, a request for increased power is received. For example, the controller118may receive a request for increased power from the input device120. This may be an accelerator pedal being pressed in a vehicle. In some embodiments, the controller118determines how many cylinders104should be activated to meet the power request. The controller118may determine an average power output for a past predefined amount of distance and/or time. The controller118may then add an upper threshold to this average. The upper threshold may correspond to the maximum power that the number of activated cylinders104of the system100may produce without reactivating any deactivated cylinders104. If the power request is greater than this threshold, the repeating activation method may proceed. If the power request is lower than this threshold, the engine103may produce the desired power without activating any additional cylinders. The power request may be based on a continual request (e.g., more than a predefined amount of time, such as two seconds) or be instantaneous. By employing this threshold, transient power fluctuations (e.g., that may be caused by short grade situations) may avoid triggering the repeating activation method500from proceeding. There may also be an analysis by the controller118of the battery116, facilitated by a sensor coupled to the battery116and the controller118. If the state of charge or other battery characteristic is above a threshold as determined by the controller118, then the controller118may direct the electric motive device114to draw power from the battery116. At process506, the electric motive device114is utilized to supplement power from the engine103. At process506, the controller118may determine the power provided by the currently activated cylinders104of the system100. Based on the determination, the controller118may command the electric motive device114to supplement the power so that the drivetrain112may provide the power required by the request received at process504. In some embodiments, the controller118commands the electric motive device114to deliver an amount of power corresponding to the number of deactivated cylinders104. For example, if one cylinder104is deactivated, the controller commands the electric motive device114to provide a first amount of power. If two cylinders104are deactivated, the controller118commands the electric motive device114to provide a second amount of power, the second amount of power greater than the first amount of power. If three cylinders104are deactivated, the controller118commands the electric motive device114to provide a third amount of power, the third amount of power greater than the second amount of power. This may be extended to any number of deactivated cylinders104. At process508, the controller118commands the valve actuation system122to cycle the deactivated cylinders104a number of times, where the number is a predetermined number (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.). In some embodiments, the number may be different for different cylinders104. In some embodiments, the number may change according to a variety of factors (e.g., requested power, temperature, air density, fuel type, etc.). For example, the controller118may determine the N number responsive to data from the sensors110and any other sensors associated with the system100. In some embodiments, the controller118commands the valve actuation system122to operate the valves106outside of the typical operating pattern while cycling the cylinders104. For example, the controller118may command the valve actuation system122close the valves106of a cylinder104once the cylinder104is determined to have desired cylinder contents, prior to completing the predetermined number of cycles. Cycling the cylinders104refreshes the cylinder contents and can equalize or substantially equalize the contents of the cylinders104, decreasing the likelihood of a NOx spike, a PM spike, or other unwanted emissions characteristic. In some embodiments, the cylinders104are cycled a predetermined amount of time (e.g., 3 seconds, 4 seconds, 5 seconds, etc.). After the cylinders104are cycled, the controller118commands the valve actuation system122to activate the cylinders104at process510. Once the cylinders104are activated, the controller118commands the electric motive device114to deactivate at process512. Alternatively, the electric motive device114may continue to be on. In some embodiments, the repeating activation method500only occurs for a subset of the deactivated cylinder104. For example, in a six-cylinder engine with four deactivated cylinders104, if the controller118determines that only four of the six cylinders104provide the requested power, the controller118only completes the repeating activation method500for two deactivated cylinders104. In some embodiments, the repeating activation method500is repeated for a plurality of cylinders104independently. FIG.6is a flow diagram of a method of supplementing power with an electric motive device, such as electric motive device114, according to another exemplary embodiment. In deactivation method600, an electric motive device114provides supplemental power while deactivating cylinders104. The deactivation method600deactivates cylinders104once the cylinders104have the desired contents, without or substantially without negatively impacting the power output. This allows for the cylinder104to be prepared for reactivation without or substantially without producing unwanted emissions, such as NOx or PM spikes. At process602, a request for a decrease in power is received. For example, controller118receives a request for a decrease in power from the input device120that is lower than a current power output (which may be an average power output over a predefined amount of time and/or distance, or an instantaneous power output when the request is received). This request may be in the form of a brake pedal being pressed in a vehicle, a transmission shift to a lower gear/setting, slowing a speed via a cruise control setting, a combination thereof, and so on. If the power request is less than a predefined power threshold, the deactivation method600may proceed. The power request may be based on a continual request (e.g., more than a predefined amount of time, such as two seconds) or be instantaneous. There may also be an analysis by the controller118of the battery116and the controller118. If the state of charge or other battery characteristic is above a threshold as determined by the controller118, then the controller118may direct the electric motive device114to draw power from the battery116. At process604, the controller118commands the electric motive device114to provide supplemental power. The supplemental power may vary during the deactivation method600. At process606, the controller118commands the valve actuation system122to cycle the cylinder104to refresh the cylinder contents. While the cylinder104is cycled, it does not produce power (e.g., combustion is disabled). The electric motive device114provides supplemental power during this step, such that the drivetrain112may still provide the requested power. The controller118may command the electric motive device114to provide supplemental power corresponding to the number of inactive cylinders104. At process608, the controller118determines the cylinder contents as described in reference to process408ofFIG.4. If the cylinder contents are determined by the controller118to be undesired for activation, the controller118commands the valve actuation system122to again cycle the cylinder104at process606. If the cylinder contents are determined by the controller118to be desired at process608, the controller118deactivates the cylinder104at process610. In some embodiments, process608may be omitted and process606may be repeated a number of times before proceeding to process610. At process612, controller118determines the power output of the remaining activated cylinders104, independent of the power provided by the electric motive device114. If the power output is determined to be equivalent or approximately equivalent to that of the power request, the controller118commands the electric motive device114to deactivate at process614. Alternatively, the electric motive device114may continue to be on. If the power output is determined to be not or substantially not equal to the power request, the deactivation method600returns to process606, such that the controller118cycles and later deactivates another cylinder104. In some embodiments, the deactivation method600is completed for multiple cylinders104simultaneously. As utilized herein with respect to numerical ranges, the terms “approximately,” “about,” “substantially,” and similar terms generally mean +/−10% of the disclosed values. When the terms “approximately,” “about,” “substantially,” and similar terms are applied to a structural feature (e.g., to describe its shape, size, orientation, direction, etc.), these terms are meant to cover minor variations in structure that may result from, for example, the manufacturing or assembly process and are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the disclosure as recited in the appended claims. It should be noted that the term “exemplary” and variations thereof, as used herein to describe various embodiments, are intended to indicate that such embodiments are possible examples, representations, or illustrations of possible embodiments (and such terms are not intended to connote that such embodiments are necessarily extraordinary or superlative examples). The term “coupled” and variations thereof, as used herein, means the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent or fixed) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members coupled direction to each other, with the two members coupled to each other using a separate intervening member and any additional intermediate members coupled with one another, or with the two members coupled to each other using an intervening member that is integrally formed as a single unitary body with one of the two members. If “coupled” or variations thereof are modified by an additional term (e.g., directly coupled), the generic definition of “coupled” provided above is modified by the plain language meaning of the additional term (e.g., “directly coupled” means the joining of two members without any separate intervening member), resulting in a narrower definition than the generic definition of “coupled” provided above. Such coupling may be mechanical, electrical, or fluidic. For example, circuit A communicably “coupled” to circuit B may signify that circuit A communicates directly with circuit B (i.e., no intermediary) or communicates indirectly with circuit B (e.g., through one or more intermediaries). While circuits with particular functionality is shown inFIG.2, it should be understood that the controller118may include any number of circuits for completing the functions described herein. For example, the activities and functionalities of certain circuits may be combined in multiple circuits or as a single circuit. Additional circuits with additional functionality may also be included. Further, the controller118may further control other activity beyond the scope of the present disclosure. As mentioned above and in one configuration, the “circuits” may be implemented in machine-readable medium storing instructions for execution by various types of processors, such as the processor202. An identified circuit of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions, which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified circuit need not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the circuit and achieve the stated purpose for the circuit. Indeed, a circuit of computer readable program code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within circuits, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network. While the term “processor” is briefly defined above, the term “processor” and “processing circuit” are meant to be broadly interpreted. In this regard and as mentioned above, the “processor” may be implemented as one or more processors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), digital signal processors (DSPs), or other suitable electronic data processing components structured to execute instructions provided by memory. The one or more processors may take the form of a single core processor, multi-core processor (e.g., a dual core processor, triple core processor, quad core processor, etc.), microprocessor, etc. In some embodiments, the one or more processors may be external to the apparatus, for example the one or more processors may be a remote processor (e.g., a cloud based processor). Alternatively or additionally, the one or more processors may be internal and/or local to the apparatus. In this regard, a given circuit or components thereof may be disposed locally (e.g., a local computing system, etc.) or remotely (e.g., as part of a remote server such as a cloud based server). To that end, a “circuit” as described herein may include components that are distributed across one or more locations. Embodiments within the scope of the present disclosure include program products comprising computer or machine-readable media for carrying or having computer or machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a computer. The computer readable medium may be a tangible computer readable storage medium storing the computer readable program code. The computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable medium may include but are not limited to a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a portable compact disc read-only memory (CD-ROM), a digital versatile disc (DVD), an optical storage device, a magnetic storage device, a holographic storage medium, a micromechanical storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, and/or store computer readable program code for use by and/or in connection with an instruction execution system, apparatus, or device. Machine-executable instructions include, for example, instructions and data which cause a computer or processing machine to perform a certain function or group of functions. The computer readable medium may also be a computer readable signal medium. A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electrical, electro-magnetic, magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport computer readable program code for use by or in connection with an instruction execution system, apparatus, or device. Computer readable program code embodied on a computer readable signal medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, Radio Frequency (RF), or the like, or any suitable combination of the foregoing In one embodiment, the computer readable medium may comprise a combination of one or more computer readable storage mediums and one or more computer readable signal mediums. For example, computer readable program code may be both propagated as an electro-magnetic signal through a fiber optic cable for execution by a processor and stored on RAM storage device for execution by the processor. Computer readable program code for carrying out operations for aspects of the present disclosure may be written in any combination of one or more other programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone computer-readable package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). The program code may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the schematic flowchart diagrams and/or schematic block diagrams block or blocks. Although the figures and description may illustrate a specific order of method steps, the order of such steps may differ from what is depicted and described, unless specified differently above. Also, two or more steps may be performed concurrently or with partial concurrence, unless specified differently above. Such variation may depend, for example, on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. The foregoing description of embodiments has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from this disclosure. The embodiments were chosen and described in order to explain the principals of the disclosure and its practical application to enable one skilled in the art to utilize the various embodiments and with various modifications as are suited to the particular use contemplated. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the embodiments without departing from the scope of the present disclosure as expressed in the appended claims. Additionally, any element disclosed in one embodiment may be incorporated or utilized with any other embodiment disclosed herein. Accordingly, the present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the disclosure is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope. | 93,307 |
11859570 | DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawings and description below essentially contain elements of certain nature. They may therefore be used not only to better understand the present disclosure, but also for contributing to the definition thereof, where applicable. In the following description, both angles measured at the level of a camshaft and called degrees CAM or °CAM and angles measured at the level of a crankshaft and called degrees CRK or °CRK are used. We have the equality 1°CAM=2°CRK since the rotational speed of a camshaft is half the rotational speed of a crankshaft on all four-stroke internal combustion engines. The description which follows relates more particularly to a camshaft toothed wheel1and such a wheel is shown schematically inFIG.1. The toothed wheel1ofFIG.1has eight teeth. Despite its relatively large number of teeth, it is intended to cooperate with a TPO-type sensor and can moreover be of a relatively small diameter, small enough to also be able to be used on engines intended to equip motorcycles. This toothed wheel1is thus intended to form a target for a camshaft position sensor of the TPO (True Power On) type. This wheel is formed from a circular disk comprising two substantially parallel opposite main faces. The disk has for example an outer radius R, for example (purely by way of nonlimiting illustration) of 20 or 25 mm. Its peripheral surface is then machined to form teeth, a recessed part each time separating two neighboring teeth. Each tooth has flanks, called edges, which each correspond to a face which can be machined of the corresponding tooth and which extends substantially radially with respect to the circular disk. Each tooth also has a top face which corresponds to the initial shape of the disk, that is to say here a circular cylindrical surface zone of radius R. The recessed parts also appear as a circular cylindrical surface zone (with possibly a rounded connection toward the flanks of the teeth). The radius of curvature of these recessed parts corresponds to the radius R of the base disk reduced by a height h, also called tooth height. It is assumed here that all the teeth of the toothed wheel have the same height. The design of the toothed wheel1presented inFIG.1corresponds to a camshaft target capable of cooperating with a TPO-type sensor making it possible to detect low levels (corresponding to a recessed part) and high levels (corresponding to a tooth). It makes it possible to ensure synchronization with a “conventional” signal supplied by a sensor associated with a crankshaft toothed wheel (for example a toothed wheel with 60 teeth minus two forming a GAP) and to give a signal every 90°CRK to precisely control variable valve timing (VVT). The use of this type of sensor imposes having, on the one hand, a sufficiently large space between the teeth to be able to detect a first edge after initialization of the sensor. Specifically, depending on the air gap distance between the target (here the toothed wheel1) and the sensor, the magnetic field detected by the sensor may vary too weakly to be able to detect the first recessed part. Conventionally, a tooth must have a minimum length Lhigh (which is generally of the order of 3 mm measured on the periphery of the target) to be correctly detected from the first revolution during an initialization of the sensor, while a recessed part must for its part have a minimum length Llow which is generally of the order of 9 mm. The measurement of this last length is done for example at the level of the periphery of the target. To be detected by a TPO-type sensor from the first revolution of the target, it is therefore necessary to have a minimum theoretical length of:arctan(Lhigh/R) for a tooth, andarctan(Llow/R) for a recessed part. With the result being an angle measured directly on the toothed wheel, it is therefore °CAM. By way of nonlimiting numerical examples, for a target of radius R=25 mm:a recessed part must then have an angular length of 19.8°CAM=arctan(9/25)a tooth must then have an angular length of 6.84°CAM=arctan(3/25). For a target with a radius of 20 mm:a recessed part must have an angular length of arctan(9/20)°CAM, i.e. 24.23°CAM=48.46°CRK.a tooth must have an angular length of arctan(3/20)°CAM, i.e. 8.53°CAM=17.06°CRK. The original proposal made here is to provide, on the one hand, a recessed part having an angular length less than arctan(8/R) and a tooth with an angular length less than arctan(2.5/R) to ensure that this recessed part and this tooth will not be detected after the initialization of the sensor. The values 8 and 2.5 are chosen to be slightly less than 9 and 3, that is to say Llow and Lhigh respectively, as a margin to make the system more robust. Thus, if a recessed part is not detected during the first rotation of the camshaft target, the signal from the sensor at this zone corresponds substantially to that of a tooth of great length. Similarly, if the tooth of short length is not detected during this first rotation, the signal from the sensor at this zone then corresponds to that of a large recessed part. There is thus inFIG.1a toothed wheel1forming a camshaft target intended to cooperate with a TPO-type sensor with:six “normal” teeth6intended to be seen by the TPO sensor during initialization. These teeth6each have an angular length greater than arctan(Lhigh/R). Thus, for example, for R=25 mm (we then have arctan(Lhigh/R)=arctan(3/25)=6.84°CAM), we choose, for example, as illustrated inFIG.1, an angular tooth length of 7°CAM, that is to say 14°CRK;a long tooth8with an angular length of 38°CAM (i.e. 76°CRK);a short tooth10with an angular length of 4.5°CAM (i.e. 9°CRK);six “normal” recessed parts16with an angular length of 38°CAM. Such a recessed part16forms with a “normal” tooth6a zone with an angular length of 45°CAM, that is to say one-eighth of a revolution;a short recessed part18with an angular length of 7°CAM. This short recessed part18forms with the long tooth8a zone with an angular length of 45°CAM, that is to say one-eighth of a revolution; anda long recessed part20with an angular length of 41.5°CAM. This long recessed part20forms with the short tooth10a zone with an angular length of 45°CAM, that is to say one-eighth of a revolution. The teeth are arranged as follows: if we consider that the TPO sensor identifies the falling edges with greater precision, that is to say that it better identifies the passage from a tooth to a recessed part, all the falling edges of the teeth are evenly distributed at the periphery of the target and are therefore offset from one another by 45°CAM (i.e. 90°CRK). In summary, the position of the edges (alternation of rising and falling edges, the first edge being rising) is for example the following (in °CRK): 30; 30+B; 120; 120+B; 210; 210+B; 210+B+E; 300+B; 390; 390+B; 480; 480+B; 570+B-D; 570+B; 660; 660+B. These values are chosen so that the falling edges (x+B) are equidistant from 90°CRK. In the example illustrated, B is chosen as being the smallest possible but large enough to allow detection during an initialization, that is to say greater than arctan(Lhigh/R), i.e. for R=25 and Lhigh=3, B>arctan(3/25) (°CAM) or even B>13.69°CRK. D corresponds to the angular length of the short tooth10. It is chosen to be less than arctan(Lhigh/R). For Lhigh=3, D will for example preferably be chosen to be less than arctan(2.5/R), that is to say for R=25 mm less than 13.69°CRK, preferably less than 11.42°CRK. Here, in the example given for R=25 mm, we took D=9°CRK. Finally, E which corresponds to the angular length of the short recessed part18is chosen to be less than arctan(Llow/R). For Llow=9 mm, E is preferably taken to be even less than arctan(8/R), that is to say for R=25 mm less than 39.61°CRK, preferably less than 35.49°CRK. Here, in the example given for R=25 mm, we took E=17°CRK. In the direction of rotation illustrated inFIG.1by the arrow4, there is a succession of recessed parts and teeth such that the angular length of a recessed part and of the tooth which follows is 45°CAM. In addition, the 45°CAM zone formed by the short recessed part18and the long tooth8is diametrically opposed to the 45°CAM zone (comprising a “normal” recessed part16and a “normal” tooth6) following the long recessed part20and the short tooth10. This is of course a preferred embodiment with numerical values given by way of nonlimiting illustration. InFIG.2, the periphery of the target (toothed wheel1) is developed flat and presented in the form of a (filtered) signal which could come from a sensor arranged facing the target. This target periphery, or signal, is placed in parallel with a similar diagram corresponding to a crankshaft target. As already mentioned, a crankshaft makes two revolutions while a camshaft makes only one. There is therefore at the top ofFIG.2a representation over 720°CRK for a representation at the bottom over 360°CAM. At the top ofFIG.2, we recognize first of all crenellations corresponding to teeth (there are 58 teeth here) and a GAP corresponding to two teeth. We have also represented the position of the top dead centers TDC (for a 3-cylinder engine, that is to say at 0°, 240° and 480°CRK. InFIG.2, synchronization is provided between the crankshaft and the camshaft so that the GAP is situated either after the short recessed part18and before the falling edge which follows, or after the short tooth10and before the falling edge which follows. In thisFIG.2, there is thus a schematic representation of a crankshaft sensor signal (at the top) and of a camshaft sensor (at the bottom) after initialization of the camshaft sensor. FIG.3is a diagram corresponding toFIG.2: the top line corresponding to the crankshaft is similar to that ofFIG.2. On the other hand, the bottom line illustrates what a TPO sensor associated with the target ofFIG.1sees during the initialization of this sensor, on the first revolution of the corresponding camshaft after starting the engine.FIG.2shows what the TPO sensor sees during the following revolutions of the camshaft. As mentioned above, the short tooth10and the short recessed part18have been designed so that they are not detected by the camshaft sensor. Thus the sensor “sees” a single “very” long tooth instead of a “normal” tooth6and the long tooth8and a single “very” long recessed part instead of a “normal” recessed part16and the long recessed part20. The synchronization is such that each GAP at the crankshaft comes to coincide with this “very” long tooth and this “very” long recessed part. This asymmetrical signal thus makes it possible to achieve synchronization. With reference toFIG.4, there is shown schematically an example of an internal combustion engine with variable timing comprising a toothed wheel according to the preceding description. The engine M comprises a crankshaft9, driving in rotation by a timing belt90at least one camshaft91, the rotation of which successively causes the opening and closing of intake and exhaust valves by cams92. Since the engine has variable timing, it may also comprise means (not shown) for angularly offsetting the camshaft to modify the opening times of the valves with respect to an identical position of the crankshaft. The maximum offsetting angle is generally of the order of 25°CAM (i.e. 50°CRK). The engine may comprise an intake camshaft91, controlling the opening and closing of the intake valves, and an exhaust camshaft91, controlling the opening and closing of the exhaust valves. In the view ofFIG.4, these two camshafts91coincide, one hiding the other which has the same shape. The crankshaft9comprises a toothed wheel93comprising a set of teeth evenly distributed at its circumference, typically 36 or 60 teeth, with the exception of one or two GAP zones, typically with one or two missing teeth. The example taken fromFIGS.2and3corresponds to 60 teeth with two GAP zones of two missing teeth each. A sensor94of the angular position of the crankshaft9is positioned facing a toothed wheel93associated with the crankshaft9and is adapted to detect the passage of each tooth of the toothed wheel93. On the camshaft91or on each camshaft is mounted a toothed wheel1. A sensor2is positioned in front of each toothed wheel1and is adapted to detect the passage of each tooth of the corresponding toothed wheel1, by detecting the rising edge or the falling edge, in the case described above, the falling edge. In the case where the engine comprises two camshafts, which is most common for a variable valve timing engine, the toothed wheels of the camshafts can either be similar or different. It is possible to use one type of toothed wheel on one camshaft and another type on the other camshaft. Likewise, the sensors2can be similar or different. It is assumed here that at least one camshaft91is equipped with a toothed wheel1as described above (or with similar characteristics). Preferably, this toothed wheel1is mounted on the camshaft91cooperating with the intake valves of the engine M and moreover, still preferably, the associated sensor2is of the TPO type. The preferred embodiment is that where the two camshaft targets are similar and the two associated sensors are also similar. The engine M also comprises a central processing unit95adapted to receive the detection signals from the angular position sensors of the crankshaft and of the camshaft, and to deduce therefrom a state of the engine cycle at each instant. The central processing unit95particularly manages the synchronization of the engine. To achieve this synchronization, the variable valve timing system is deactivated and the camshafts91remain in a predetermined position, or neutral position. When the engine is started, each camshaft91makes a first revolution. The sensor2associated with the camshaft91(or each camshaft) provided with a toothed wheel1similar to that illustrated inFIG.1operates with a first sensitivity which does not allow it to distinguish, on the one hand, the short tooth10and, on the other hand, the short recessed part18. Thus, during this first revolution, the sensor2considered sees the passage of five similar teeth and one longer tooth, just as it sees the passage of five similar recessed parts and one longer recessed part. To recognize this signal supplied by the sensor2, the central processing unit95compares it with a first signal model corresponding to the signal supposed to be supplied by a target with five similar teeth and one longer tooth. Thus the signal supplied by the sensor2is recognized by the central processing unit95and synchronization with the signal received by the sensor94of the angular position of the crankshaft9. The longer tooth is detected simultaneously with the passage of a first GAP of the toothed wheel93associated with the crankshaft9while the longer recessed part is detected simultaneously with the passage of a second GAP of the toothed wheel93. In this way, it is possible to distinguish the passage of the first GAP from the passage of the second GAP and thus to know precisely the position of the engine over 720°CRK. During the second revolution of the camshaft, the sensitivity of the sensor2associated with the camshaft91provided with a toothed wheel1similar to that illustrated inFIG.1is increased so that the associated sensor2identifies the passage, on the one hand, of the short tooth10and, on the other hand, of the short recessed part18. Thus, subsequently, the eight falling edges of the toothed wheel1are identified at each rotation of the corresponding camshaft91and the variable valve timing (VVT) benefits from a signal every 90°CRK for its control. For this second revolution and the following ones, the signal from the sensor2is compared in the central processing unit95with a second signal model with a falling edge every 90°CRK. In an original manner, two models of signals (or targets) are stored in the central processing unit95. INDUSTRIAL APPLICATION The technical solution described above takes advantage of a drawback of TPO-type sensors to propose a toothed wheel design which is both compact and which makes it possible to supply a signal every 90°CRK. During a first passage, depending on the air gap distance between the sensor and the target, the magnetic field detected by the sensor varies too weakly to be able to detect all the edges. Internal learning in the sensor2is carried out to allow correct detection from the second revolution of the camshaft (and its associated target). This characteristic of TPO-type sensors is generally considered to be a weakness because it requires taking the margin in the dimensioning of the targets in order to be able to detect the passage of the teeth, in particular the first tooth, with certainty. Poor detection generally generates a failure in the synchronization method because the succession of detected edges does not correspond to the stored model and which should have been detected. Until now, it was considered that the use of a TPO sensor allowed quick synchronization because it allows a detection of the levels but did not make it possible to carry out quick control of a variable valve timing. Here, in an original manner, a first stored model is used for the first revolution of the target and a second stored model is used subsequently. The proposed solution also has good synchronization performance because different tooth levels are arranged facing the GAP markers on the crankshaft. Thus synchronization can be performed on average over 230°CRK thanks also to the use of two distinct models for synchronization. The use of a target which would comprise eight teeth distributed at the periphery of the target and a ninth tooth to create an asymmetry in the profile of the target would lead a priori to an average value of the order of 360°CRK to achieve synchronization of the engine. The proposed solution can be proposed both on a camshaft controlling the intake valves and the exhaust valves. It is possible in the same engine to have two similar targets on the camshafts and two sensors associated with said targets which are similar as well. Thus the number of separate parts in the engine is limited, which is favorable because it makes it possible to reduce costs without compromising in terms of quality. The present disclosure is not limited to the exemplary embodiments described and mentioned above, solely by way of examples, but it encompasses all the variants that those skilled in the art may consider in the context of the protection sought. | 18,578 |
11859571 | DETAILED DESCRIPTION The following description relates to systems and methods for estimation of a road surface metric and adjusting vehicle operation such as exhaust gas recirculation (EGR) and VDE mechanism activation based on the metric. An example vehicle operating on a road is shown inFIG.1. The vehicle may include an internal combustion engine and a plurality of sensors for measuring road roughness conditions as shown inFIG.2. An engine controller is configured to perform control routines, such as the example routines ofFIG.3-5, to determine a plurality of parameters for estimation of a road roughness index (RRI). Estimation of the RRI and adjusting one or more engine operating associated with improved fuel economy at elevated NVH during rough road conditions is elaborated inFIG.6. Turning now toFIG.1illustrating a side view schematics of a vehicle100. The vehicle may include four wheels130and be driven on a surface of a road105. A distinct speed sensor may be coupled to each vehicle wheel such as wheel speed sensors132and134. A speed of rotation of a respective wheel may be estimated based on output of the wheel speed sensors132,134. A vehicle speed sensor136may be coupled to the vehicle body. A rate of change of vehicle speed may also be estimated based on output of the speed sensor136. A coordinate system for the vehicle may be defined with its origin at the center of gravity of the vehicle. A first, longitudinal axis112may be a pitch axis of the vehicle and body pitch may be longitudinal rotational motion of the vehicle body about the first axis112(such as a dip down of the nose of the vehicle relative to the tail) A second, latitudinal (lateral) axis114may be a roll axis of the vehicle and body roll may be an axial rotational motion of the vehicle body about the second axis114such as to lean in a direction of perceived centrifugal force acting upon the vehicle. A third, vertical axis116may be a yaw axis of the vehicle and body yaw may be a rotational motion of the vehicle body about the third axis116. When moving forward, the vehicle may travel along the positive x-axis of the Cartesian coordinate150on the road105. Separate acceleration sensors (accelerometers) including a first longitudinal acceleration (about axis112) sensor, a second latitudinal acceleration (about axis114) sensor, and a third yaw rate (about axis116) sensor may be coupled to the vehicle. The front of the vehicle100may include an active grille shutter (AGS) system210. The AGS210may be a dual active grille shutter system comprising two groups of one or more grille shutters configured to adjust the amount of ambient airflow received through grille. In another example, the AGS system210may be an active grille shutter system comprising a single group of one or more grille shutters. Vertically below the AGS210such as between the AGS210and the road, is an air dam211. The air dam211may reduce or nullify the effect of undesired air movement across the vehicle when it is in motion. The air dam211may also generate a down-force as the air passes around the vehicle, thereby improving vehicle stability and traction control at higher speeds. Vehicle height H1 can refer to the front vehicle height of the vehicle such as the distance between the surface of the road on which the vehicle is operating and a nose of the vehicle100. Vehicle100may comprise an active suspension system that enables the control system to regulate vertical positioning of the vehicle wheels130relative to the vehicle body. Active suspension system may comprise having hydraulic, electrical, and/or mechanical devices, as well as active suspension systems that control the vehicle height on an individual corner basis (e.g., four corner independently controlled vehicle heights), on an axle-by-axle basis (e.g., front axle and rear axle vehicle heights), or a single vehicle height for the entire vehicle. For example, the active suspension system may include hydraulic or electronic actuators that may raise and lower a vehicle body chassis independently at each wheel. Additionally or alternately, the active suspension system may include shock absorbers coupled at each wheel that can be varied in firmness, depending on vehicle operating conditions. In this way, the control system may raise or lower the front and rear of the vehicle independently in response to vehicle operating conditions. FIG.2is a schematic diagram showing one cylinder of a multi-cylinder engine10in an engine system200. The engine system200, may be coupled inside a propulsion system of an on road vehicle system201. In one example vehicle201may be vehicle100inFIG.1. The engine10may be controlled at least partially by a control system including a controller12and by input from a vehicle operator232via an input device230. In this example, the input device230includes an accelerator pedal and a pedal position sensor234for generating a proportional pedal position signal. A combustion chamber30of the engine10includes a cylinder formed by cylinder walls32with a piston36positioned therein. The piston36may be coupled to a crankshaft40so that reciprocating motion of the piston is translated into rotational motion of the crankshaft. The crankshaft40may be coupled to at least one drive wheel of a vehicle via an intermediate transmission system. Further, a starter motor may be coupled to the crankshaft40via a flywheel to enable a starting operation of the engine10. In one example, engine10may be a boosted engine system wherein intake air received in engine cylinders are compressed by an intake compressor (not shown). When included, the intake compressor may be a supercharger compressor driven by a motor or a turbocharger compressor driven by an exhaust turbine. Alternatively, engine10may be naturally aspirated. The combustion chamber30may receive intake air from an intake manifold44via an intake passage42and may exhaust combustion gases via an exhaust passage (e.g., exhaust pipe)48. The intake manifold44and the exhaust pipe48can selectively communicate with the combustion chamber30via respective intake valve52and exhaust valve54. In some examples, the combustion chamber30may include two or more intake valves and/or two or more exhaust valves. In this example, the intake valve52and exhaust valve54may be controlled by cam actuation via respective cam actuation systems51and53. The cam actuation systems51and53may each include one or more cams and may utilize one or more of cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and/or variable valve lift (VVL) systems that may be operated by the controller12to vary valve operation. The position of the intake valve52and exhaust valve54may be determined by position sensors55and57, respectively. In alternative examples, the intake valve52and/or exhaust valve54may be controlled by electric valve actuation. For example, the cylinder30may alternatively include an intake valve controlled via electric valve actuation and an exhaust valve controlled via cam actuation including CPS and/or VCT systems. A fuel injector69is shown coupled directly to combustion chamber30for injecting fuel directly therein in proportion to the pulse width of a signal received from the controller12. In this manner, the fuel injector69provides what is known as direct injection of fuel into the combustion chamber30. The fuel injector may be mounted in the side of the combustion chamber (as shown) or in the top of the combustion chamber, for example. Fuel may be delivered to the fuel injector69by a fuel system (not shown) including a fuel tank, a fuel pump, and a fuel rail. In some examples, the combustion chamber30may alternatively or additionally include a fuel injector arranged in the intake manifold44in a configuration that provides what is known as port injection of fuel into the intake port upstream of the combustion chamber30. Spark is provided to combustion chamber30via spark plug66. The ignition system may further comprise an ignition coil (not shown) for increasing voltage supplied to spark plug66. In other examples, such as a diesel, spark plug66may be omitted. The intake passage42may include a throttle62having a throttle plate64. In this particular example, the position of throttle plate64may be varied by the controller12via a signal provided to an electric motor or actuator included with the throttle62, a configuration that is commonly referred to as electronic throttle control (ETC). In this manner, the throttle62may be operated to vary the intake air provided to the combustion chamber30among other engine cylinders. The position of the throttle plate64may be provided to the controller12by a throttle position signal. The intake passage42may include a mass air flow sensor120and a manifold air pressure sensor122for sensing an amount of air entering engine10. An exhaust gas sensor126is shown coupled to the exhaust pipe48upstream of both an exhaust gas recirculation system140and an emission control device70according to a direction of exhaust flow. The sensor126may be any suitable sensor for providing an indication of exhaust gas air-fuel ratio such as a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen), a two-state oxygen sensor or EGO, a HEGO (heated EGO), a NOx, HC, or CO sensor. In one example, upstream exhaust gas sensor126is UEGO configured to provide output, such as a voltage signal, that is proportional to the amount of oxygen present in the exhaust. Controller12converts oxygen sensor output into exhaust gas air-fuel ratio via an oxygen sensor transfer function. Engine10may be a variable displacement engine (VDE) having separate cylinder banks such as a first bank and a second bank with equal or unequal number of engine cylinders. During selected conditions, such as when the full torque capability of the engine is not needed, one of a first or a second cylinder group may be selected for deactivation (herein also referred to as a VDE mode of operation). Specifically, one or more cylinders of the selected group of cylinders may be deactivated by shutting off respective fuel injectors, and deactivating the intake and exhaust valves. While fuel injectors of the disabled cylinders are turned off, the remaining enabled cylinders continue to carry out combustion with fuel injectors active and operating. To meet the torque requirements, the engine produces the same amount of torque on those cylinders for which the injectors remain enabled. This requires higher manifold pressures, resulting in lowered pumping losses and increased engine efficiency. Also, the lower effective surface area (from only the enabled cylinders) exposed to combustion reduces engine heat losses, improving the thermal efficiency of the engine. Cylinders may be grouped for deactivation in a bank-specific manner. For example, the first group of cylinders may include the four cylinders of the first bank while the second group of cylinders may include the four cylinders of the second bank. In an alternate example, instead of one or more cylinders from each bank being deactivated together, two cylinders from each bank of the engine may be selectively deactivated together. However, during activation of the VDE mechanism such as when one or more cylinders are deactivated or subsequently reactivated, there may be an increase in vehicle NVH which may restrict the use of VDE mechanism in order to maintain operator satisfaction. An exhaust gas recirculation (EGR) system140may route a desired portion of exhaust gas from the exhaust pipe48to the intake manifold44via an EGR passage152. EGR reduces pumping work of an engine resulting in increased fuel economy. In addition, EGR effectively cools combustion chamber temperatures thereby reducing NOx formation and improving emissions quality. EGR may also be used to regulate the temperature of the air-fuel mixture within the combustion chamber, thus providing a method of controlling the timing of ignition during some combustion modes. In the depicted example, the EGR delivered is a low-pressure EGR (LP-EGR), wherein a portion of exhaust gas from the exhaust pipe48may be delivered from downstream of a turbocharger turbine (not shown) to the engine intake manifold44, upstream of a turbocharger compressor (not shown). In an alternate example, the EGR delivered may be a high-pressure EGR (HP-EGR), wherein a portion of exhaust gas from the exhaust pipe48may be delivered from upstream of a turbocharger turbine (not shown) to the engine intake manifold44, downstream of a turbocharger compressor (not shown). In addition to exhaust gases, fuel vapors hydrocarbons may also be delivered to the engine intake manifold44for combustion in cylinder30. For example, fuel vapors stored in a fuel vapor canister (coupled to a fuel tank of the engine's fuel system) may be intermittently purged to the engine intake manifold via purge port90. The fuel vapors stored in the canister may include refueling vapors, as well as diurnal fuel vapors. Purge flow (including air and canister fuel vapors) along purge port90may be controlled via a purge valve (also known as a canister purge valve, not shown). In one example, purge flow may be enabled responsive to a hydrocarbon load of a fuel system canister being higher than a threshold load. In another example, purge flow may be enabled during selected engine operating conditions when air-fuel excursions induced by the ingestion of fuel vapors can be minimized. The amount of EGR (LP-EGR or HP-EGR) provided to the intake manifold44may be determined based on engine operating conditions and further based on NVH constraints. NVH constraints may be based on road roughness conditions. Maximum permissible (target level) EGR flow rate may be determined for a given set of engine operating conditions, such as based on engine speed and load. However, during high EGR flow rates, there may be an increase in vehicle NVH due to poor combustion. Accordingly, an engine control system may operate the engine with sub-optimal levels (lower than the target level) of EGR to improve vehicle drivability and reduce operator dissatisfaction. For example, for a given engine speed-load condition, the actual EGR delivered may be lower than the maximum permissible or target EGR for the given speed-load condition, the actual EGR limited from the target EGR based on an amount of combustion instability generated. As an example, in response to an indication of engine roughness, as indicated by an increase in misfire events, EGR may be lowered from the target EGR. As a consequence of the EGR being limited, the full fuel economy potential of EGR in an engine may be reduced. However the inventors herein have recognized that during rough road conditions, based on engine operating conditions, EGR flow may be selectively increased to the target level and VDE mechanism may be activated as the NVH resulting from the elevated EGR and VDE mechanism activation may be masked by the NVH resulting from the rough road conditions. Consequently, a vehicle operator may not perceive any further change in NHV due to the increased EGR levels or VDE activation while higher fuel economy is achieved. In the same manner, the amount of purge flow provided to the intake manifold44may be determined based on engine operating conditions and further based on NVH constraints. A maximum permissible (target level) purge flow rate may be determined for a given set of engine operating conditions, such as based on engine speed and load, and further based on canister load. However, during high purge flow rates, there may be an increase in vehicle NVH due to misdistribution of the ingested fuel vapors and poor combustion. Accordingly, an engine control system may operate the engine with sub-optimal levels (lower than the target level) of purge and/or positive crankcase ventilation (PCV) flow to improve vehicle drivability and reduce operator dissatisfaction. For example, for a given engine speed-load condition, the actual purge flow delivered may be lower than the maximum permissible or target purge flow for the given speed-load condition, the actual purge flow limited from the target purge flow based on an amount of combustion instability generated. As a consequence of the purge flow being limited, the full fuel economy potential of fuel vapor ingestion in an engine may be limited. However the inventors herein have recognized that during higher RRI conditions, purge flow may be selectively increased to (or towards) the target level as the NVH resulting from the elevated fuel vapor flow may be masked by the NVH resulting from the rough road conditions. Rough road conditions may be detected based on the output of various vehicle sensors coupled external to the engine. As non-limiting examples, sensors used for estimating road roughness may include four wheel speed sensors80positioned at the four wheels, a vehicle speed sensor82coupled to the vehicle body, and a yaw-rate sensor84, a longitudinal acceleration (first) sensor86, and a latitudinal acceleration (second) sensor88provided as part of a dynamic suspension system of the vehicle or integrated within the vehicle body near a center of gravity of the vehicle. Still other sensors include a crankshaft acceleration sensor, a suspension sensor, and a wheel slip sensor. Readings from one or more of the above-mentioned sensors may be combined over a distance traveled by the vehicle to determine the RRI of the road on which the vehicle is travelling. Estimation of a rough road index (RRI) and use of the RRI for adjustments of engine parameters is elaborated herein with reference toFIGS.3-6. In one example, the RRI may be estimated as a weighted average of a pitch energy, a roll energy, a first absolute wheel speed deviation energy, a second absolute wheel speed deviation energy, a third absolute wheel speed deviation energy, and a fourth absolute wheel speed deviation energy. The pitch energy of the vehicle may be estimated as a function of an acceleration of the vehicle along a longitudinal axis of the vehicle as estimated via a first acceleration sensor86, and a rate of change of speed of the vehicle as estimated based on an output of a vehicle speed sensor80, and the roll energy is estimated as a function of an acceleration of the vehicle along a latitudinal axis of the vehicle as estimated via a second acceleration sensor88, a speed of the vehicle as estimated via the vehicle speed sensor, and a yaw rate of the vehicle as estimated via a yaw rate sensor84. Each of the pitch energy and the roll energy may be estimated over a first threshold distance, the first threshold distance corresponding to one car length. The first absolute wheel speed deviation energy may be a function of a first wheel speed of the first wheel as estimated via a first wheel speed sensor, the second absolute wheel speed deviation energy may be a function of a second wheel speed of the second wheel as estimated via a second wheel speed sensor, the third absolute wheel speed deviation energy may be a function of a third wheel speed of the third wheel as estimated via a third wheel speed sensor, and the fourth absolute wheel speed deviation energy may be a function of a fourth wheel speed of the fourth wheel as estimated via a fourth wheel speed sensor. The first absolute wheel speed deviation energy may be estimated over a first threshold rotational distance, the second absolute wheel speed deviation energy is estimated over a second threshold rotational distance, the third absolute wheel speed deviation energy is estimated over a third threshold rotational distance, and the fourth absolute wheel speed deviation energy is estimated over a fourth threshold rotational distance. The first threshold rotational distance may be one rotation of the first wheel, the second threshold rotational distance may be one rotation of the second wheel, the third threshold rotation distance may be one rotational of the third wheel, and the fourth threshold rotation distance may be one rotation of the fourth wheel. In response to the RRI being higher than a threshold, it may be inferred that an increased NVH is generated upon travelling on that road surface and the vehicle may be operated with a fuel economy mode enabled. Operating the vehicle in the fuel economy mode may include adjusting one or more engine operating parameters causing an increase in engine NVH, the one or more engine operating parameters include selectively increasing a flow rate of exhaust gas recirculation (EGR) to an engine intake manifold. The selective increasing may include increasing the flow rate from a first EGR level based on engine speed-load conditions and an engine NVH limit to a second EGR level based on the engine speed-load conditions and independent of the engine NVH limit. Further, in the fuel economy mode, one or more cylinders may be deactivated via actuation of the variable displacement engine (VDE) mechanism. The emission control device70is shown inFIG.2arranged along the exhaust pipe48, downstream of the exhaust gas sensor126. The device70may be a three way catalyst (TWC), NOxtrap, various other emission control devices, or combinations thereof. In some examples, during operation of the engine10, the emission control device70may be periodically reset by operating at least one cylinder of the engine within a particular air-fuel ratio. A particulate filter72is shown arranged along the exhaust pipe48downstream of the emission control device70. Exhaust gas treated by emission control device70and particulate filter72is released into the atmosphere through tailpipe87. The particulate filter72may be a diesel particulate filter or a gasoline particulate filter. The controller12is shown inFIG.1as a microcomputer, including a microprocessor unit102, input/output ports104, an electronic storage medium for executable programs and calibration values shown as read only memory chip106(e.g., non-transitory memory) in this particular example, random access memory108, keep alive memory110, and a data bus. The controller12may receive various signals from sensors coupled to the engine10, in addition to those signals previously discussed, measurement of inducted mass air flow (MAF) from the mass air flow sensor120; engine coolant temperature (ECT) from a temperature sensor113coupled to a cooling sleeve115; an engine position signal from a Hall effect sensor118(or other type) sensing a position of crankshaft40; throttle position from a throttle position sensor65; and manifold absolute pressure (MAP) signal from the sensor122. An engine speed signal and crankshaft acceleration may be generated by the controller12from crankshaft position sensor118. Vehicle wheel speed may be estimated based on output from the wheel speed sensor(s)80. The angular velocity and slip-angle of the vehicle may be measured using the yaw-rate sensor84. Acceleration sensors86and88may provide acceleration estimates in longitudinal and latitudinal directions. A vehicle speed sensor may provide estimates of vehicle speed and a rate of change in vehicle posed. Manifold pressure signal also provides an indication of vacuum, or pressure, in the intake manifold44. Note that various combinations of the above sensors may be used, such as a MAF sensor without a MAP sensor, or vice versa. During engine operation, engine torque may be inferred from the output of MAP sensor122and engine speed. Further, this sensor, along with the detected engine speed, may be a basis for estimating charge (including air) inducted into the cylinder. In one example, the crankshaft position sensor118, which is also used as an engine speed sensor, may produce a predetermined number of equally spaced pulses every revolution of the crankshaft. The storage medium read-only memory106can be programmed with computer readable data representing non-transitory instructions executable by the processor102for performing the methods described below as well as other variants that are anticipated but not specifically listed. The controller12receives signals from the various sensors ofFIGS.1-2and employs the various actuators ofFIG.2to adjust engine operation based on the received signals and instructions stored on a memory of the controller12. In one example, during increase in road roughness conditions, the controller12may send a signal to an actuator coupled to an EGR valve144to increase the opening of the EGR valve144in order to increase EGR flow rate. In this way, the components described inFIGS.1-2enable a system for a controller storing instructions in non-transitory memory that, when executed, cause the controller to: estimate a longitudinal acceleration of the vehicle via a longitudinal accelerometer (such as sensor86), estimate a latitudinal acceleration of the vehicle via a latitudinal accelerometer (such as sensor88), estimate a yaw rate of the vehicle via a yaw rate sensor (such as sensor84), estimate a speed of the vehicle and a rate of change of the speed of the vehicle via a vehicle speed sensor (such as sensor80), estimate a pitch energy of the vehicle over a threshold distance based on the estimated longitudinal acceleration and the rate of change of the speed, estimate a roll energy of the vehicle over the threshold distance based on the estimated latitudinal acceleration, the yaw rate, and the speed, estimate a road roughness index (RRI) based on the estimated pitch energy and roll energy, and in response to the RRI being higher than a threshold, selectively deactivating one or more engine cylinders via a variable displacement engine (VDE) mechanism while maintain combustion in remaining engine cylinders. FIG.3illustrates an example method300for estimating pitch energy of the vehicle relative to the road surface, in real-time, based on conditions of a road on which a vehicle is travelling. The pitch energy of the vehicle may provide an estimate of the vehicle's dynamics separate from the road surface. The estimation of the pitch energy may be distance filtered over a threshold distance of travel on the road surface. Instructions for carrying out method300may be executed by a controller based on instructions stored on a memory of the controller and in conjunction with signals received from sensors of the engine system and the vehicle system, such as the sensors described above with reference toFIGS.1and2. The controller may employ engine actuators of the engine system to adjust engine operation, according to the methods described below. At302, the routine includes estimating and/or measuring current engine and vehicle operating conditions. Conditions assessed may include, for example, engine load, engine speed, vehicle speed, rate of change of vehicle speed, engine temperature, throttle position, exhaust pressure, exhaust air/fuel ratio, ambient conditions (such as ambient temperature, pressure, and humidity), vehicle acceleration along longitudinal and latitudinal directions, yaw rate, etc. At304, the acceleration of the vehicle along the longitudinal axis (such as pitch axis112inFIG.1), Longatt, may be estimated as a function of the output of a longitudinal acceleration sensor (such as longitudinal acceleration sensor86inFIG.2). Longattmay be an estimation on the vehicle pitch angle relative to gravity. Longattmay be computed using equation 1. Longatt=sin-1(longaccg)3602π(1)where Longattis the acceleration of the vehicle along the longitudinal axis, longaccis the output of the longitudinal acceleration sensor, and g is acceleration due to gravity. At306, the vehicle pitch angle relative to gravity (Dymlong), may be estimated as a function of a rate of change in vehicle speed. Dymlongmay be an indication of the vehicle acceleration due to propulsion (average acceleration rate the vehicle is causing for itself). Dymlongmay be computed using equation 2. Dymlong=sin-1(vsrateg)3602π(2)where Dymlongis the vehicle pitch angle relative to gravity, vsrateis the rate of change in vehicle speed, and g is acceleration due to gravity. At308, an instantaneous pitch angle (Instatt) of the vehicle body relative to gravity may be estimated based on a difference between Longattand Dymlong. Instattmay correspond to an instantaneous measurement from the longitudinal acceleration sensor. At310, a short term pitch (Staticatt) of the vehicle may be estimated based on the Instat. The Staticattmay be filtered over a threshold distance such as over one car length. Staticattmay be computed using equation 3. Staticatt=distfilt(Instatt) (3)where Staticattis the short term pitch of the vehicle, Instattis the instantaneous pitch angle, and distfiltis a distance filter applied on the instantaneous pitch angle. At312, an instantaneous body pitch (Instpitch) of the vehicle may be estimated based on Instattand Staticatt. The Instpitchmay provide an estimate of how much the front end of the vehicle (such as the nose of the vehicle) is moving along the y-axis (up and down) relative to the road surface. In one example, if the Instpitchis higher than a threshold, the suspension may adjust the height of the vehicle. Also, if the front of the vehicle moves close to the road surface and is within a threshold distance to the road surface (such as within 6 inches), the air dam may be adjusted (raised and/or lowering disabled) upon the front of the vehicle moving closer to the road surface. At314, absolute pitch energy of the vehicle body from the road over the distance may be estimated based on Instpitch. The pitch energy or pitchness of the vehicle may be an indication of variation in vehicle body pitch from average pitch. The pitch energy provides an estimation of an amount of impact provided by the road surface to the body causing the body to move along the y-axis relative to the road surface. The pitch energy may be computed using equation 4. Pitchness=abs(UpLwrEnv(Instpitch)) (4)where Pitchness is the pitch energy of the vehicle body as the absolute value obtained from using an upper and lower envelope filter (peak and valley detector with decay) on the instantaneous body pitch (Instpitch). One or more additional filters may also be used such as over time. FIG.4illustrates an example method400for estimating roll energy of the vehicle relative to the road surface, in real-time based on conditions of a road on which a vehicle is travelling. The estimation of the roll energy may be distance filtered over a threshold distance of travel on the road surface. At402, the routine includes estimating and/or measuring current engine and vehicle operating conditions. Conditions assessed may include, for example, engine load, engine speed, vehicle speed, rate of change of vehicle speed, engine temperature, throttle position, exhaust pressure, exhaust air/fuel ratio, ambient conditions (such as ambient temperature, pressure, and humidity), vehicle acceleration along longitudinal and latitudinal directions, yaw rate, etc. At404, the acceleration of the vehicle along the latitudinal axis (such as roll axis114inFIG.1), Latatt, may be estimated as a function of the output of a latitudinal (lateral) acceleration sensor (such as latitudinal acceleration sensor88inFIG.2). Latattmay be an estimation of the vehicle roll angle relative to gravity. The Longattmay be computed using equation 5. Latatt=sin-1(lataccg)3602π(5)where Latattis the acceleration of the vehicle along the latitudinal axis, lataccis the output of the latitudinal acceleration sensor, and g is acceleration due to gravity. At406, the vehicle roll angle relative to gravity (Dymlat), may be estimated as a function of vehicle speed, front wheel speed, rear wheel speed, and yaw rate. Dymlatmay be an indication of the vehicle lateral acceleration due to dynamic motion such as turn/slip. Dymlatmay be computed using equation 6. Dymlat=sin−1{(k1k2vspd(wr−wl)+(1−k1)k3Yawrate)} (6)where Dymlatis the vehicle roll angle relative to gravity, vspd is the vehicle speed, wris the right wheel speed, wlis the left wheel speed, Yawrate is the output of the yaw rate sensor, and k1, k2, k3are constants. Dymlatprovides an estimate of how far the left and right side of the vehicle can move up and down relative to the road surface. At408, an instantaneous roll angle (Instlat) of the vehicle body relative to gravity may be estimated based on a difference between Latattand Dymlat. Instlatmay correspond to an instantaneous measurement from the latitudinal acceleration sensor. At410, a short term roll (Staticlat) of the vehicle may be estimated based on the Instlat. The Staticlatmay be filtered over a threshold distance such as over one car length. Staticlatmay be computed using equation 7. Staticlat=distfilt(Instlat) (7)where Staticlatis the short term roll of the vehicle, Instlatis the instantaneous roll angle, and distfiltis a distance filter applied on the instantaneous roll angle. At412, an instantaneous body roll (Instroll) of the vehicle may be estimated based on Instlatand Staticlat. The Instrollmay provide an estimate of the lateral motion of the vehicle body relative to the road surface. At414, absolute roll energy of the vehicle body from the road over the distance may be estimated based on Instroll. The roll energy or rolliness of the vehicle may be an indication of variation in vehicle body roll from average roll. The roll energy provides an estimation of an amount of impact provided by the road surface to the body causing the body to move laterally relative to the road surface. The roll energy may be computed using equation 8. Rolliness=abs(UpLwrEnv(Instroll)) (8)where Rolliness is the roll energy of the vehicle body as the absolute value obtained from using an upper and lower envelope filter (peak and valley detector with decay) on the instantaneous body roll. One or more additional filters may also be used such as over time. FIG.5illustrates an example method500for estimating wheel speed deviation energy for each wheel of the vehicle, in real-time based on conditions of a road on which the vehicle is travelling. At502, the routine includes estimating and/or measuring current engine and vehicle operating conditions. Conditions assessed may include, for example, engine load, engine speed, vehicle speed, rate of change of vehicle speed, engine temperature, throttle position, exhaust pressure, exhaust air/fuel ratio, ambient conditions (such as ambient temperature, pressure, and humidity), vehicle acceleration along longitudinal and latitudinal directions, yaw rate, wheel speeds, etc. At504, an average speed (Staticspd) of a first wheel may be estimated over a threshold distance as a function of speed of the first wheel as estimated via a speed sensor coupled to the first wheel. In one example, the distance may be one rotation of the wheel. Staticspdmay be an estimation of how much the wheel is speeding up or slowing down on average over the threshold distance. Staticspdmay be computed using equation 9. Staticspd=distfilt(wheelspd) (9)where Staticspdis the average speed of the first wheel, wheelspdis the output of the speed sensor on the first wheel, and distfiltis a distance filter. At506, an instantaneous deviation in speed (Instspd) of the first wheel may be estimated over the threshold distance based on a difference between the speed of the first wheel (wheelspd) and the average speed of the first wheel Staticspd. Instspdmay provide an estimation of the first wheel gaining or losing any speed over the threshold (rotational) distance. At508, an average deviation in speed (Instdev) of the first wheel may be estimated based on the instantaneous deviation in speed, Instspd. Instdevmay be computed using equation 10. Instdev=UpLwrEnv(Instspd) (10)where Instdevis the average deviation in speed of the first wheel and UpLwrEnv is an upper and lower envelope filter applied on the instantaneous deviation in speed, Instspd. At510, an actual deviation in speed of the first wheel (Hpfdev) may be estimated over the threshold distance based on a difference between the instantaneous deviation in speed (Instspd) of the first wheel and the average deviation in speed (Instdev) of the first wheel over the threshold distance. The Hpfdevmay provide an estimate of an actual rebound on the tire as the wheel travels on the road surface. At512, an absolute wheel speed deviation energy (upspd) of the first wheel may be estimated based on the actual deviation in speed of the first wheel (Hpfdev). The upspdmay correspond to an energy content of the first wheel as it moves along the road surface and may be proportional to the impact energy on the tire of the first wheel. The absolute wheel speed deviation energy may be computed using equation 11. upspd=abs(UpLwrEnv(distance,Instdev)) (11)where upspdis the energy of the first wheel as the absolute value obtained from using an upper and lower envelope filter (peak and valley detector with decay) on the instantaneous deviation in speed of the first wheel over the threshold distance. One or more additional filters may also be used such as over time. At514, the respective absolute wheel speed deviation energy for each of the vehicle wheels may be estimated over the threshold duration following the steps discussed in504-512. In a vehicle with four wheels, the absolute wheel speed deviation energy may be estimated for each of the four wheels separately based on respective outputs of the wheel speed sensors. FIG.6illustrates an example method600for estimating a road roughness index (RRI) and adjusting engine operation based on the estimated roughness. The road roughness index may provide an estimation of roughness on the road that may cause NVH in the vehicle while being driven on the road. At602, a pitch energy (Pitchness) of the vehicle body relative to the road surface may be estimated based on the method elaborated inFIG.3. The pitch energy may provide an estimate of an absolute pitch variation in the vehicle per unit distance travelled along the road surface. At604, a roll energy (Rolliness) of the vehicle body relative to the roads surface may be estimated based on the method elaborated inFIG.4. Similar to the pitch energy, the roll energy may provide an estimate of an absolute roll variation in the vehicle per unit distance travelled along the road surface. At606, absolute wheel speed deviation energy for each wheel (upspd1, upspd2, upspd3, upspd4) may be estimated based on the method elaborated inFIG.5. Each of the four wheel speed deviation energy values provide estimate of absolute wheel angle variation per distance for that wheel travelled along the roadway. At608, the road roughness index (RRI) may be estimated based on each of the estimated pitch energy, the roll energy, and the four absolute wheel speed deviation energies. In one example, the RRI may be estimated as weighted average of each of the pitch energy, the roll energy, and the four absolute wheel speed deviation energies. In another example, a non-linear map of RRI may be obtained by statistical combination (such as average/maxima/minima/median) of the pitch energy, the roll energy, and the four absolute wheel speed deviation energies. A road with a lower RRI may have a smoother surface and vehicle operation on the smoother surface may cause a lower level of NVH relative to travel on a road with a higher RRI. At610, the routine includes determining if the RRI of the road surface is higher than a pre-calibrated threshold RRI. The threshold RRI may correspond to a level of road roughness at which sufficient NVH may be generated while driving on the road to mask undesirable sounds in the engine. When the RRI is higher than the threshold, there may be an opportunity to increase the level of one or more engine operating parameters, such as the EGR level and the purge frequency or actuate a VDE mechanism, since the increased NVH due to the road roughness may mask any NVH resulting from the change in the operating parameter (such as the EGR or VDE engagement). If it is determined that the RRI is lower than the threshold RRI, at612, the fuel economy mode is disabled. The fuel economy mode may include activation or increase of engine operating parameters such as activation of VDE and increase in EGR flow rate which may improve fuel economy but may increase engine NVH. For example, the EGR flow rate may be maintained at a lower level and/or the VDE mechanism may be maintained disabled such that the increased NVH is not perceived by the operator. If it is determined that the RRI index is higher than the threshold RRI, it may be inferred that the NVH generated by the vehicle travel on the road may be sufficient to mask any further NVH caused by change in engine operation. Therefore, at614, a fuel economy mode may be enabled regardless of the increased NHV concerns from the change in engine operation. The fuel economy mode may include, at615, adjusting cylinder deactivation using the VDE mechanism. In one example, cylinder deactivation may be enabled when torque demand is less than a pre-calibrated threshold. Upon confirmation of a VDE mode of operation, a group of cylinders and/or an engine bank to be deactivated may be selected based on the estimated engine operating conditions. The selection may be based on, for example, which group of cylinders was deactivated during a previous VDE mode of operation. For example, if during the previous cylinder deactivation condition, a first group of cylinders on a first engine bank were deactivated, then a controller may select a second group of cylinders on a second engine bank for deactivation during the present VDE mode of operation. As another example, the selection may be based on a regeneration state of a first exhaust catalyst (or emission control device) coupled to the first bank relative to the regeneration state of a second exhaust catalyst (or emission control device) coupled to the second bank. Following the selection, the controller may selectively deactivate one or more engine cylinders. As used herein, the deactivation may include selectively deactivating (e.g., turning off) a fuel injector of the selected one or more engine cylinders. While deactivating fuel injection to the selected group of cylinders, the controller may continue to operate (e.g., open or close) intake and exhaust valves of the deactivated cylinders so as to flow air and/or exhaust gases through the deactivated cylinders. In one example, where the engine is a V8 engine, during a VDE mode, the engine may be operated with one group of cylinders activated (that is, in a V4 mode) while during the non-VDE mode, the engine may be operated with both groups of cylinders activated (that is, in a V8 mode). By operating the engine with lower number of combusting cylinders during lower torque demand conditions, fuel economy may be improved. The fuel economy mode may further include, at616, adjusting EGR flow rate. Increasing the EGR flow rate may include increasing an opening of the EGR valve coupled in a low pressure EGR passage. A target EGR flow rate may be estimated based on engine operating conditions such as engine speed, engine load, and engine temperature. For example, the controller may send a signal to an actuator coupled to the EGR valve to increase the opening of the EGR valve to enable EGR flow at the target EGR level. By increasing the EGR flow rate to the target level, engine fuel economy is improved. At the same time, any increase in engine roughness due to a drop in combustion quality at the higher EGR level may be masked by the NVH associated with rough road conditions and therefore may not be perceptible to the vehicle operator. The fuel economy mode may further include opportunistically updating one or more other additional engine operating parameters to improve fuel economy and engine performance. The parameters may include (but are not limited to) use of spark retard during a transmission gear shift schedule, torque convertor slip schedule, purge frequency, altering exhaust cam phasing in a variable cam timing (VCT) engine, and initialization of on-board diagnostic routines. Any increase in NVH experienced due to a change in one or more of the above-mentioned parameters would be masked by the increased NVH levels associated with the rough road conditions. For example, a purge frequency may be increased allowing for more purge flow vapors to be ingested in the engine during rough road conditions. As another example, a transmission gear shift may be scheduled earlier during the rough road condition so that they can be completed during the rough road condition. In addition, they may be scheduled with the use of less spark retard. As yet another example, on-board diagnostic monitors that may be intrusive and cause potential NVH concerns may be initialized during rough road conditions without causing any noticeable deterioration in NVH levels. As yet another example, if a torque converter slip was scheduled to eliminate NVH, less slip (or more lock-up) may be scheduled to reduce fuel loss. For example, a lock-up clutch of the torque converter may be configured to slip less during the gear shift. As still another example, an engine knock threshold may be raised to a level that allows for the use of more spark advance. Likewise, an engine pre-ignition threshold may be raised to allow for improved pre-ignition detection in the presence of rough road conditions. As with the increase in EGR, the adjustment of each of the other operating parameters may be increased until engine misfires are indicated, and then the increase may be capped or limited. For example, EGR may be reduced under the misfire limit. The inventors have recognized that the increasing regulation for fuel economy and emissions have led to many new technologies being developed for spark ignition gasoline engines. For example, transmissions can either slip the lock up clutch, or lock and unlock the torque convertor during gear shifting to make shifts feel smooth. Additionally, to make shifts smooth, large spark retard may be used to match torque levels before and after a gear change. Both slipping and opening of the torque convertor clutch, and large spark retard from MBT result in decreased fuel economy. Another example may be the engine lug limit. At low engine speed and moderate load the vehicle may vibrate, and lug resulting in poor NVH characteristics. Typically this is mitigated by slipping or opening the torque convertor clutch allowing the engine speed to be raised relative to wheel speed avoiding the lugging area. However, during rough road conditions, a torque convertor slip or lock up schedule can be modified, as well as the spark retard used for torque control can be adjusted. Since it will be difficult for the operator to discern the rough road NVH from the powertrain NVH, the powertrain could be operated more efficiently. For example when on a rough road, during a shifting event, the torque converter may be left locked, or slipped less (e.g., 10% on a rougher road vs 20% on a smoother road), the slippage depending on the roughness of the road. Also during the shift events, spark may be retarded less for torque matching (e.g., 25 deg. retarded from MBT on a rougher road vs 35 deg. retarded from MBT on a smoother road). Similar slip percentage changes could also be done during the lugging period. All these modifications result in improved fuel economy, which may provide customers more real world fuel economy improvement where roads are unimproved, or benefit customers in countries where road conditions are poor, and improved fuel economy is appreciated. It will be appreciated that as with EGR, the one or more other engine operating parameters may be adjusted (e.g., increased) until a misfire count becomes higher than a threshold. Thereafter, the parameter may be reduced. Specifically, if misfires are detected while providing the elevated purge level, the increase in purge flow may be limited or reduced to the misfire limit level of purge. The limit may be a mapped limit, including a safety margin for misfire/poor combustion in the presence of noise factors (such as humidity, and part to part variation). In this way it is possible to change engine operating parameter during rough road conditions, thereby improving engine performance. In this way, during a first condition, in response to an estimated road roughness index (RRI) being lower than a threshold level, an amount of EGR delivered to an engine may be maintained at a lower than a target amount of EGR, and during a second condition, in response to the estimated RRI being higher than the threshold level, the amount of EGR delivered to the engine may be increased to the target amount of EGR, the RRI estimated based on an each of an estimated pitch energy of the vehicle and an estimated roll energy of the vehicle. AT618, a position of the air dam may be adjusted based on the RRI. In one example, during a higher than threshold RRI, the air dam may be raised to avoid contact of the air dam with the road surface. In this way, by estimating a RRI as a function of each of an estimated vehicle pitch energy, vehicle roll energy, and absolute wheel speed deviation energy from each vehicle wheel, an accurate estimation of road roughness may be attained for improved vehicle operation adjustments. The technical effect of adjusting engine operation such as EGR supply and cylinder deactivation based on the RRI is that the NVH caused by the change in engine operations may be masked by the vehicle's VNH caused by travelling on a rough road, thereby making the engine adjustments not perceivable by the operator. Overall, by opportunistically adjusting the mentioned engine operations, fuel efficiency and emissions quality. An example method for a vehicle comprises: estimating a road roughness index (RRI) of a road based on one or more of a pitch energy and a roll energy of the vehicle travelling on the road, and in response to a higher than threshold road roughness, enabling a fuel economy mode of the vehicle. In the preceding example, additionally or optionally, the pitch energy is estimated as a function of an acceleration of the vehicle along a longitudinal axis of the vehicle as estimated via a first acceleration sensor, and a rate of change of a speed of the vehicle as estimated based on an output of a vehicle speed sensor. In any or all of the preceding examples, additionally or optionally, the roll energy is estimated as a function of an acceleration of the vehicle along a latitudinal axis of the vehicle as estimated via a second acceleration sensor, the speed of the vehicle as estimated via the vehicle speed sensor, and a yaw rate of the vehicle as estimated via a yaw rate sensor. In any or all of the preceding examples, additionally or optionally, each of the pitch energy and the roll energy is estimated over a first threshold distance, the first threshold distance corresponding to one car length. In any or all of the preceding examples, additionally or optionally, the RRI is further estimated based on each of a first absolute wheel speed deviation energy of a first wheel, a second absolute wheel speed deviation energy of a second wheel, a third absolute wheel speed deviation energy of a third wheel, and a fourth absolute wheel speed deviation energy of a fourth wheel. In any or all of the preceding examples, additionally or optionally, the first absolute wheel speed deviation energy is a function of a first wheel speed of the first wheel as estimated via a first wheel speed sensor, wherein the second absolute wheel speed deviation energy is a function of a second wheel speed of the second wheel as estimated via a second wheel speed sensor, wherein the third absolute wheel speed deviation energy is a function of a third wheel speed of the third wheel as estimated via a third wheel speed sensor, and wherein the fourth absolute wheel speed deviation energy is a function of a fourth wheel speed of the fourth wheel as estimated via a fourth wheel speed sensor. In any or all of the preceding examples, additionally or optionally, the first absolute wheel speed deviation energy is estimated over a first threshold rotational distance, the second absolute wheel speed deviation energy is estimated over a second threshold rotational distance, the third absolute wheel speed deviation energy is estimated over a third threshold rotational distance, and the fourth absolute wheel speed deviation energy is estimated over a fourth threshold rotational distance. In any or all of the preceding examples, additionally or optionally, the first threshold rotational distance is one rotation of the first wheel, the second threshold rotational distance is one rotation of the second wheel, the third threshold rotation distance is one rotational of the third wheel, and the fourth threshold rotation distance is one rotation of the fourth wheel. In any or all of the preceding examples, additionally or optionally, the RRI is estimated as a weighted average of the pitch energy, the roll energy, the first absolute wheel speed deviation energy, the second absolute wheel speed deviation energy, the third absolute wheel speed deviation energy, and the fourth absolute wheel speed deviation energy. In any or all of the preceding examples, additionally or optionally, operating the vehicle in the fuel economy mode includes adjusting one or more engine operating parameters causing an increase in engine noise, vibration, and hoarseness (NVH), the one or more engine operating parameters include selectively increasing a flow rate of exhaust gas recitation (EGR) to an engine intake manifold. In any or all of the preceding examples, additionally or optionally, the selectively increasing includes increasing the flow rate increased from a first EGR level based on engine speed-load conditions and an engine NVH limit to a second EGR level based on the engine speed-load conditions and independent of the engine NVH limit. In any or all of the preceding examples, additionally or optionally, the one or more engine operating parameters include deactivating one or more cylinders via actuation of a variable displacement engine (VDE) mechanism. Another example method for an engine coupled to an on-road vehicle, comprises: during a first condition, in response to an estimated road roughness index (RRI) being lower than a threshold level, maintaining an amount of EGR delivered to the engine lower than a target amount of the EGR; and during a second condition, in response to the estimated RRI being higher than the threshold level, increasing the amount of the EGR delivered to the engine to the target amount of the EGR, the RRI estimated based on an each of an estimated pitch energy of the vehicle and an estimated roll energy of the vehicle. In the preceding example, additionally or optionally, the pitch energy of the vehicle is estimated as a function of a longitudinal acceleration of the vehicle and a rate of change of vehicle speed, and wherein the roll energy is estimated as a function of a lateral acceleration of the vehicle, a speed of the vehicle, and a yaw rate of the vehicle. In any or all of the preceding examples, additionally or optionally, each of the pitch energy and the roll energy is filtered over a threshold distance. In any or all of the preceding examples, additionally or optionally, the RRI is estimated based on a weighted average of each of the roll energy, the pitch energy, a first absolute wheel speed deviation energy of a first wheel, a second absolute wheel speed deviation energy of a second wheel, a third absolute wheel speed deviation energy of a third wheel, and a fourth absolute wheel speed deviation energy of a fourth wheel. In any or all of the preceding examples, additionally or optionally, the first absolute wheel speed deviation energy is a function of a speed of the first wheel over a threshold rotational distance, wherein the second absolute wheel speed deviation energy is a function of a speed of the second wheel over the threshold rotational distance, wherein the third absolute wheel speed deviation energy is a function of a speed of the third wheel over the threshold rotational distance, and wherein the fourth absolute wheel speed deviation energy is a function of a speed of the fourth wheel over the threshold rotational distance. Another example for a vehicle, comprises: a controller storing instructions in non-transitory memory that, when executed, cause the controller to: estimate a longitudinal acceleration of the vehicle via a longitudinal accelerometer, estimate a latitudinal acceleration of the vehicle via a latitudinal accelerometer, estimate a yaw rate of the vehicle via a yaw rate sensor, estimate a speed of the vehicle and a rate of change of the speed of the vehicle via a vehicle speed sensor, estimate a pitch energy of the vehicle over a threshold distance based on the estimated longitudinal acceleration and the rate of change of the speed, estimate a roll energy of the vehicle over the threshold distance based on the estimated latitudinal acceleration, the yaw rate, and the speed, estimate a road roughness index (RRI) based on the estimated pitch energy and roll energy, and in response to the RRI being higher than a threshold, selectively deactivating one or more engine cylinders via a variable displacement engine (VDE) mechanism while maintain combustion in remaining engine cylinders. In any of the preceding examples, additionally or optionally, the controller includes further instructions to: estimate a first speed of a first wheel via a first wheel speed sensor, estimate a second speed of a second wheel via a second wheel speed sensor, estimate a third speed of a third wheel via a third wheel speed sensor, estimate a fourth speed of a fourth wheel via a fourth wheel speed sensor, and estimate a first absolute wheel speed deviation energy, a second absolute wheel speed deviation energy, a third absolute wheel speed deviation energy, and a fourth absolute wheel speed deviation energy based on the first speed, the second speed, the third speed, and the fourth speed, respectively. In any or all of the preceding examples, additionally or optionally, the RRI is estimated as a weighted average of each of the pitch energy, the roll energy, the first absolute wheel speed deviation energy, the second absolute wheel speed deviation energy, the third absolute wheel speed deviation energy, and the fourth absolute wheel speed deviation energy. Note that the example control and estimation routines included herein can be used with various engine and/or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be carried out by the control system including the controller in combination with the various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various actions, operations, and/or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations, and/or functions may be repeatedly performed depending on the particular strategy being used. Further, the described actions, operations, and/or functions may graphically represent code to be programmed into non-transitory memory of the computer readable storage medium in the engine control system, where the described actions are carried out by executing the instructions in a system including the various engine hardware components in combination with the electronic controller. It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. Moreover, unless explicitly stated to the contrary, the terms “first,” “second,” “third,” and the like are not intended to denote any order, position, quantity, or importance, but rather are used merely as labels to distinguish one element from another. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein. As used herein, the term “approximately” is construed to mean plus or minus five percent of the range unless otherwise specified. The following claims particularly point out certain combinations and sub-combinations regarded as novel and non-obvious. These claims may refer to “an” element or “a first” element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure. | 61,884 |
11859572 | DETAILED DESCRIPTION Embodiments of the present disclosure will be described below with reference to the accompanying drawings. It is intended, however, that unless particularly identified, dimensions, materials, shapes, relative positions, and the like of components described in the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present disclosure. For instance, an expression of relative or absolute arrangement such as “in a direction”, “along a direction”. “parallel”, “orthogonal”. “centered”, “concentric” and “coaxial” shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance, or by an angle or a distance whereby it is possible to achieve the same function. For instance, an expression of an equal state such as “same” “equal” and “uniform” shall not be construed as indicating only the state in which the feature is strictly equal, but also includes a state in which there is a tolerance or a difference that can still achieve the same function. Further, for instance, an expression of a shape such as a rectangular shape or a cylindrical shape shall not be construed as only the geometrically strict shape, but also includes a shape with unevenness or chamfered corners within the range in which the same effect can be achieved. On the other hand, an expression such as “comprise”, “include”, “have”, “contain” and “constitute” are not intended to be exclusive of other components. (Overall Configuration) FIG.1is a diagram of an overall configuration of an engine and auxiliaries according to some embodiments.FIG.2is a cross-sectional view schematically showing the configuration of an engine according to an embodiment.FIG.3is a cross-sectional view schematically showing the configuration of an engine according to another embodiment.FIG.4is a diagram showing the configuration regarding a fuel injection system of the engine shown inFIGS.2and3.FIG.5is a block configuration diagram of a fuel injection control device according to an embodiment.FIG.6is a graph showing the relationship between the momentum of fuel in a cylinder and the momentum of swirl stored in a corresponding momentum storage part. An engine1according to some embodiments is, for example, a uniflow type two-stroke diesel engine. The engine1according to some embodiments includes an engine body11, a control device (ECU)13, a fuel pump15, a common rail17, a fuel injection valve19, and a turbocharger5. The engine1according to some embodiments includes an air cooler2, a scavenging manifold3, and an exhaust manifold4. The turbocharger5has a compressor51for compressing combustion air and a turbine52driven by exhaust gas. In the engine1according to some embodiments, the compressor51compresses the air. The air compressed by the compressor51is cooled by the air cooler2and supplied into a cylinder20of the engine body11via the scavenging manifold3. Further, fuel supplied from the fuel injection valve19into the cylinder20self-ignites due to the heat of compression, so that the fuel burns and expands in the cylinder20. Further, exhaust gas produced in the cylinder20is discharged to the exhaust manifold4. The exhaust gas discharged to the exhaust manifold4flows into the turbine52of the turbocharger5and drives a turbine impeller (not shown) to rotate, thereby driving the compressor51. The control device13is a control device for controlling each part of the engine1. The fuel pump15is a pump for supplying fuel to the engine1. The common rail17is a pressure accumulation device for accumulating the fuel supplied from the fuel pump15at a predetermined supply pressure. The fuel injection valve19is a fuel injection device for injecting the fuel supplied from the common rail17into the cylinder20, as described above. As shown inFIGS.2and3, the engine1according to some embodiments includes at least one cylinder20and at least one piston30disposed in the at least one cylinder20. The engine1according to some embodiments may be, for example, a multi-cylinder engine. In the engine1according to some embodiments, the at least one cylinder20has a plurality of fuel injection valves19. In the engine1shown inFIGS.2and3, for example, two fuel injection valves19are disposed per cylinder. In the engine1according to some embodiments, for example, the two fuel injection valves19disposed per cylinder may be arranged at an even angular pitch about the central axis of the cylinder20. The fuel injection valve19is configured to open only w % bile receiving a valve opening signal from the control device13to be able to inject the supplied fuel. In the engine1according to some embodiments, the fuel injection valve19is configured to inject the fuel into the cylinder20in a direction of swirling around the central axis of the cylinder20(hereinafter, also simply referred to as the swirling direction). The control device13according to some embodiments is configured to control each part so as to inject the fuel at an injection pressure corresponding to a momentum in the swirling direction of a swirl flow (hereinafter, also referred to as the momentum of swirl or the swirl momentum Σma·va), which is a flow of the combustion air formed in the cylinder20. The control contents in the control device13according to some embodiments will be described in detail later. (Engine1A) The engine1A shown inFIG.2is, for example, an opposed-piston engine. In each of the at least one cylinder20, a pair of pistons30is disposed in the same cylinder20and is configured to move in opposite directions along the axial direction of the cylinder20. That is, in the engine1A shown inFIG.2, the at least one piston30includes a first piston31and a second piston32disposed opposite to the first piston31in the same cylinder20where the first piston31is disposed. For example, the engine1A shown inFIG.2is a single-cylinder opposed-piston engine having one cylinder, but may be a multi-cylinder opposed-piston engine having not less than two cylinders. In the engine1A shown inFIG.2, the first piston31is connected to one end of a connecting rod43via a piston pin41, and the other end of the connecting rod43is connected to a first crankshaft211. Likewise, the second piston32is connected to one end of a connecting rod43via a piston pin41, and the other end of the connecting rod43is connected to a second crankshaft221. In the engine1A shown inFIG.2, the first piston31and the second piston32reciprocate in the cylinder20in synchronization with each other by rotation of the first crankshaft211about a first output shaft213and rotation of the second crankshaft221about a second output shaft223. In the engine1A shown inFIG.2, at least one scavenging port26is formed in a peripheral wall20aof each cylinder20on one axial side of the cylinder20, and at least one exhaust port27is formed in the peripheral wall20aof the cylinder20on the other axial side of the cylinder20. In the engine1A shown inFIG.2, multiple scavenging ports26and exhaust ports27are arranged in the circumferential direction of each cylinder20. In the engine1A shown inFIG.2, the scavenging ports26are connected to the scavenging manifold3, and the exhaust ports27are connected to the exhaust manifold4. In the engine1A shown inFIG.2, for example, the port angle of each scavenging port26is set so that the air flowing from the scavenging manifold3into the cylinder20forms a swirl flow in the cylinder20. In the engine1A shown inFIG.2, the fuel injection valve19is disposed on the peripheral wall20aof each cylinder20. In the engine1A shown inFIG.2, for example, two fuel injection valves19are disposed to be displaced in the circumferential direction so as to be opposite to each other across the axis of each cylinder20(the center of radial cross-section in each cylinder20). (Engine1B) The engine1B shown inFIG.3is, for example, a uniflow type two-stroke diesel engine in which one piston30is disposed in one cylinder20. For example, the engine1B shown inFIG.3is a single-cylinder engine having one cylinder, but may be a multi-cylinder engine having not less than two cylinders. In the engine1B shown inFIG.3, the piston30is connected to one end of a connecting rod43via a piston pin41, and the other end of the connecting rod43is connected to a crankshaft210. In the engine1B shown inFIG.3, the piston30reciprocates in the cylinder20by rotation of the crankshaft210about an output shaft215. In the engine1B shown inFIG.3, at least one scavenging port26is formed in the peripheral wall20aof the cylinder20on one axial side (bottom dead center side) of the cylinder20, and at least one exhaust port27is formed in a cylinder head28disposed on the other axial side (top dead center side) of the cylinder20. In the engine1B shown inFIG.3, multiple scavenging ports26are disposed in the circumferential direction of the cylinder20. In the engine1B shown inFIG.3, opening/closing of the exhaust port27is controlled by an exhaust valve29. In the engine1B shown inFIG.3, the scavenging ports26are connected to the scavenging manifold3, and the exhaust port27is connected to the exhaust manifold4. In the engine1B shown inFIG.3, for example, the port angle of each scavenging port26is set so that the air flowing into the cylinder20from the scavenging manifold3forms a swirl flow in the cylinder20. In the engine1B shown inFIG.3, for example, the fuel injection valve19is disposed on the cylinder head28. In the engine1B shown inFIG.3, for example, two fuel injection valves19are disposed to be displaced in the circumferential direction so as to be opposite to each other across the axis of the cylinder20, and the fuel is injected in a direction including a component in a swirl flow direction. (Fuel Injection Pressure Control) As described above, in a general diesel engine, the fuel injection conditions are determined based on a control map regarding the relationship between the load of the diesel engine and the fuel injection conditions such as fuel injection pressure. However, for example, in a two-stroke diesel engine, if the pressure balance of scavenging and exhaust gas changes, the air flow rate into the cylinder and the state of in-cylinder swirl change. The pressure balance of the scavenging and exhaust gas changes not only according to engine operating conditions but also according to changes in atmospheric conditions and temporal change in the engine. Therefore, if the fuel injection conditions are simply determined based on the control map, a good combustion state may not be obtained. In view of this, the engine1according to some embodiments is configured to estimate the swirl flow state in the cylinder20as follows, and inject the fuel into the cylinder20at an injection pressure suitable for the estimated swirl flow state. Details will now be described. FIG.7is a diagram schematically showing an example of fuel injection pattern in the cylinder20. As a result of diligent studies by the inventors, it was found that a good combustion state can be obtained when the relationship between the swirl momentum Σma·va and the momentum of fuel in the cylinder20in the swirling direction R (hereinafter, also referred to as the fuel momentum Σmf·vf) is appropriate. If the flow state of the swirl flow65changes such that the swirl momentum Σma·va is excessively large relative to the fuel momentum Σmf·vf in the cylinder20due to the change in the pressure balance of scavenging and exhaust gas, for example, the injected fuel spray61may interfere with an inner wall surface (cylinder wall surface)20bof the cylinder20in the vicinity of the injection position63, and the combustion state may not be good. Conversely, if the swirl momentum Σma·va is excessively small relative to the fuel momentum Σmf·vf in the cylinder20due to the change in the pressure balance of scavenging and exhaust gas, for example, the injected fuel spray61may interfere with the spray61from the opposite fuel injection valve19or interfere with a cylinder wall surface20bopposite to the injection position63, and the combustion state may not be good. That is, as a result of diligent studies by the inventors, it was found that a good combustion state can be obtained by approximating the relationship between the swirl momentum Σma·va and the fuel momentum Σmf·vf to the correspondence as shown by line L in the graph ofFIG.6. The line L in the graph ofFIG.6shows an example when the relationship between the swirl momentum Σma·va and the fuel momentum Σmf·vf is appropriate. The region on the lower right side of the line L in the graph ofFIG.6is a region where the swirl momentum Σma·va is large relative to the fuel momentum Σmf·vf in the cylinder20. Further, the region on the upper left side of the line L in the graph ofFIG.6is a region where the swirl momentum Σma·va is small relative to the fuel momentum Σmf·vf in the cylinder20. In the engine1according to some embodiments, the control device13has the fuel injection control device100as a function block. The fuel injection control device100controls the injection pressure of fuel, as described below. (Fuel Injection Control Device100) As shown inFIG.5, the fuel injection control device100according to an embodiment has a scavenging and exhaust gas state quantity acquisition part101, an in-cylinder air amount calculation part103, a swirl flow intensity calculation part143, a swirl momentum calculation part110, a fuel injection pressure calculation part120, and an injection amount determination part131as function blocks. Further, the fuel injection pressure calculation part120includes a fuel momentum calculation part121and an injection pressure determination part122. The fuel injection control device100according to an embodiment includes a various information storage part141and a corresponding momentum storage part145as a storage part140for storing various information. (Scavenging and Exhaust Gas State Quantity Acquisition Part101) The scavenging and exhaust gas state quantity acquisition part101is a function block for acquiring a parameter related to the state quantity of scavenging and exhaust gas in the cylinder20. In the fuel injection control device100according to an embodiment, the scavenging and exhaust gas state quantity acquisition part101acquires, for example, the pressure Psc in the scavenging manifold3, the temperature Tsc in the scavenging manifold3, and the pressure Pex in the exhaust manifold4. The scavenging and exhaust gas state quantity acquisition part101may be configured to acquire the pressure Psc and the temperature Tsc in the scavenging manifold3from a pressure sensor and a temperature sensor (not shown) installed in the scavenging manifold3. Further, the scavenging and exhaust gas state quantity acquisition part101may be configured to acquire the pressure Pex in the exhaust manifold4from a pressure sensor (not shown) installed in the exhaust manifold4. (In-Cylinder Air Amount Calculation Part103) The in-cylinder air amount calculation part103is a function block for calculating the air amount in the cylinder from the scavenging density and the cylinder internal volume. Specifically, the in-cylinder air amount calculation part103calculates the scavenging density ρsc on the basis of the pressure Psc in the scavenging manifold3and the temperature Tsc in the scavenging manifold3acquired by the scavenging and exhaust gas state quantity acquisition part101. The volume Vsc in the cylinder20at the end of the scavenging stroke can be obtained in advance from the cylinder diameter, stroke length, connecting rod length, compression ratio, and scavenging stroke end time (that is, the arrangement position of the scavenging port26) in the engine1. The air amount ma trapped in the cylinder20is obtained from the scavenging density ρsc and the volume Vsc of the cylinder20at the end of the scavenging stroke. (Swirl Flow Intensity Calculation Part143) The swirl flow intensity calculation part143is a function block for calculating the swirl flow intensity vsl in the cylinder20at the end of the scavenging stroke. The swirl flow intensity vsl is calculated according to the differential pressure Δ (Psc−Pex) between the pressure Psc in the scavenging manifold3and the pressure Pex in the exhaust manifold4acquired by the scavenging and exhaust gas state quantity acquisition part101on the basis of the relationship between the swirl flow intensity and the scavenging and exhaust differential pressure acquired in advance by steady flow test or CFD analysis of the scavenging port26in the engine1. (Swirl Momentum Calculation Part110) The swirl momentum calculation part110is a function block for calculating the momentum of swirl (swirl momentum Marva) generated in the cylinder20. In the fuel injection control device100according to an embodiment, the swirl momentum calculation part110calculates the swirl momentum Σma·va on the basis of the air amount in the cylinder20, that is, the in-cylinder trapped air amount ma and the swirl flow intensity va in the cylinder20at the end of the piston compression. The relationship between the swirl flow intensity vsl at the end of scavenging and the swirl flow intensity va at the end of piston compression is previously incorporated as a formula or a map by acquiring the relationship between two according to the engine rotation speed of the engine1by CFD or the like. Then, the swirl momentum calculation part110calculates the swirl flow intensity va at the end of piston compression in the cylinder20using the formula or the map on the basis of the swirl flow intensity vsl at the end of scavenging calculated by the swirl flow intensity calculation part143and the engine rotation speed, and calculates the swirl momentum Σma·va on the basis of the swirl flow intensity va and the in-cylinder trapped air amount ma. (Injection Amount Determination Part131) In the injection amount determination part131, the fuel injection amount mf is determined by a PID controller on the basis of the difference between the measured engine torque or rotation speed each time and the target engine torque or rotation speed so that the required engine output can be obtained. (Various Information Storage Part141) The various information storage part141is a storage part which stores various data required for calculating a fuel injection pressure target value Pf*, which will be described later. In the fuel injection control device100according to an embodiment, for example as described above, the various information storage part141stores data on scavenging and exhaust characteristics of the engine1acquired in advance by element test or numerical simulation, data on the volume Vsc of the cylinder20at the end of the scavenging stroke, and data on fuel injection characteristics of the fuel injection valve19. (Corresponding Momentum Storage Part145) The corresponding momentum storage part145is a storage part which previously stores the fuel momentum Σmf·vf in the cylinder20corresponding to the swirl momentum Σma·va. In the fuel injection control device100according to an embodiment, the corresponding momentum storage part145stores conditions with which the relationship between the swirl momentum Σma·va and the fuel momentum Σmf·vf is appropriate, as shown in the graph ofFIG.6, for example. (Fuel Injection Pressure Calculation Part120) The fuel injection pressure calculation part120is a function block for calculating the injection pressure Pf of fuel (fuel injection pressure target value Pf*) from the fuel injection valve19corresponding to the swirl momentum Σma·va calculated by the swirl momentum calculation part110. In the fuel injection control device100according to an embodiment, the fuel injection pressure calculation part120reads out, from the corresponding momentum storage part145, the fuel momentum Σmf·vf corresponding to the swirl momentum Σma·va calculated by the swirl momentum calculation part110, and calculates the fuel injection pressure target value Pf* on the basis of the fuel momentum Σmf·vf read out from the corresponding momentum storage part145. Specifically, in the fuel injection pressure calculation part120of the fuel injection control device100according to an embodiment, the fuel momentum calculation part121reads out a necessary fuel momentum Σmf·vf according to the swirl momentum Σma·va calculated by the swirl momentum calculation part110from data on the relationship between the swirl momentum Σma·va and the fuel momentum Σmf·vf stored in the corresponding momentum storage part145on the basis of the swirl momentum Σma·va calculated by the swirl momentum calculation part110. The relationship between the fuel injection pressure target value Pf* and the fuel injection speed Vf is previously obtained and derived as fuel injection characteristic data in the fuel injection valve19by element test or numerical simulation. Then, in the fuel injection pressure calculation part120of the fuel injection control device100according to an embodiment, the injection pressure determination part122calculates the injection pressure Pf of fuel required for obtaining the fuel momentum Emf-vf as the fuel injection pressure target value Pf* on the basis of the fuel momentum Σmf·vf read out from the corresponding momentum storage part145and the fuel injection amount mf calculated by the injection amount determination part131. In the engine1according to some embodiments, the control device13may be configured to control the fuel pump15so that the rail pressure Pr of the common rail17reaches the fuel injection pressure target value Pf* calculated as described above. The present disclosure is not limited to the embodiments described above, but includes modifications to the embodiments described above, and embodiments composed of combinations of those embodiments. The contents described in the above embodiments would be understood as follows, for instance. (1) A fuel injection control device100according to at least one embodiment of the present disclosure is a device for controlling fuel injection performed by a fuel injection device (fuel injection valve19) disposed in a cylinder20of a two-stroke engine, comprising: a scavenging and exhaust gas state quantity acquisition part101configured to acquire a parameter related to the state quantity of scavenging and exhaust gas in the cylinder20; a swirl momentum calculation part110configured to calculate the momentum of swirl (swirl momentum Σma·va) generated in the cylinder20on the basis of the parameter; and a fuel injection pressure calculation part120configured to calculate an injection pressure Pf of fuel from the fuel injection valve19corresponding to the swirl momentum Σma·va calculated by the swirl momentum calculation part110. According to the above configuration (1), since fuel can be injected at the injection pressure Pf corresponding to the swirl momentum Σma·va calculated by the swirl momentum calculation part110, for example, even if the pressure balance of scavenging and exhaust gas changes, a good combustion state can be obtained, so that the reduction in thermal efficiency in a two-stroke engine can be suppressed. (2) In some embodiments, in the above configuration (1), the fuel injection control device100according to at least one embodiment further comprises a corresponding momentum storage part145previously storing the momentum of fuel (fuel momentum Σmf·vf) in the cylinder20corresponding to the swirl momentum Σma·va. The fuel injection pressure calculation part120is configured to read out, from the corresponding momentum storage part145, the fuel momentum Σmf·vf corresponding to the swirl momentum Σma·va calculated by the swirl momentum calculation part110, and calculate the injection pressure Pf of fuel from the fuel injection valve19on the basis of the fuel momentum Emf-vf read out from the corresponding momentum storage part145. According to the above configuration (2), the relationship between the swirl momentum Σma·va and the fuel momentum Σmf·vf in the cylinder20is likely to be kept appropriate, so that a good combustion state can be easily obtained. (3) In some embodiments, in the above configuration (1) or (2), the fuel injection control device100according to at least one embodiment further comprises a swirl flow intensity calculation part143configured to calculate the swirl flow intensity vsl in the cylinder20during the scavenging stroke on the basis of the differential pressure Δ (Psc−Pex). The swirl momentum calculation part110is configured to calculate the swirl flow intensity va in the cylinder20at the end of piston compression on the basis of the swirl flow intensity vsl at the end of the scavenging stroke calculated by the swirl flow intensity calculation part143, and calculate the swirl momentum Σma·va on the basis of the swirl flow intensity va in the cylinder20and the air amount (in-cylinder trapped air amount ma) in the cylinder20. According to the above configuration (3), it is possible to improve the calculation precision of the swirl momentum Σma·va. REFERENCE SIGNS LIST 1,1A,1B Engine5Turbocharger11Engine body13Control device (ECU)15Fuel pump17Common rail19Fuel injection valve20Cylinder26Scavenging port27Exhaust port100Fuel injection control device101Scavenging and exhaust gas state quantity acquisition part103In-cylinder air amount calculation part110Swirl momentum calculation part120Fuel injection pressure calculation part143Swirl flow intensity calculation part145Corresponding momentum storage part | 25,649 |
11859573 | DESCRIPTION An Emission Control System (ECS) for an automobile is designed to fulfill Environmental Protection Agency (EPA) mandates to reduce harmful emissions. As one function, the ECS protects the automobile by adjusting the air to fuel (e.g., gasoline) ratio in the mixture that is combusted. Current ECS include an oxygen sensor located in an exhaust pipe of the automobile to generate a signal that is sent to an electronic control unit (ECU). In response, the ECU can raise or lower the air to fuel ratio of the mixture. FIG.1is a schematic diagram of components of an automobile10, including an internal combustion engine (ICE)11having an intake manifold12. An electrical control unit (ECU)13is operatively coupled with the ICE11in order to control air to fuel ratio of the mixture provided to the ICE11based on signals from an oxygen sensor14. The ECU13and oxygen sensor14are communicatively coupled through a wire harness15. A battery16is coupled with an interface circuit17to transform signals from the oxygen sensor14to the ECU when hydrogen is being provided to the ICE11. The interface circuit17is coupled to the wire harness5through a connection assembly8(e.g., a pair of pigtail connections21aand21b) in order to provide modification to signals from the oxygen sensor14when an electrolysis cell19provides hydrogen to the ICE11. The interface circuit17is connected with an input port22aand an output port22bof the interface circuit17. The water cell19can be controlled with a suitable circuit box20. Wires23connect the battery with the interface circuit17. A wire24connects the battery16with the electrolysis water cell19and a wire25connects the electrolysis cell with the circuit box20. A further wire26connects the circuit box20with the battery16. The water cell19contains water that will be converted to hydrogen and oxygen by electrolysis. The water cell19further includes a water tank27that charges negative ions and regulates the impurity of distilled water that is forced to the electrolysis water cell19so as to control amperage. During operation, power from the battery16is provided to the water cell19, where water within tank19is split into hydrogen and oxygen. This mixture is then provided into the intake manifold12and mixed with ambient air. The fuel (e.g., gasoline) is also injected into the ambient air-hydrogen mixture in the ICE11. The ICE11ignites the mixture to produce power through combustion. A cooling coil and capture container28can be provided to capture water from the exhaust of the ICE11. Carbon capture from this water and the water can be recycled from container28. In a conventional automobile, the oxygen sensor14sends a signal to the ECU13. Dependent upon the signal from the oxygen sensor14, the ECU13will protect various valves and other elements (e.g., a catalytic converter) associated with the ICE11by modifying operation of the ICE11. When hydrogen is further supplied to the intake manifold12, the oxygen sensor14produces a signal indicative of low levels of hydrocarbons in the exhaust of the ICE11. As a result, the ECU13will adjust operation of the ICE11to increase enrichment of the fuel. However, this situation is undesirable when using hydrogen as an additive with ICE11. When interface circuit17is in operation, the circuit17adds voltage to the signal from the oxygen sensor14. The oxygen sensor14signal can gate a switch (e.g. a MOSFET) of the interface circuit17. In particular, the switch creates a hard pulse that is sent to the ECU13. In response, the ECU13determines that hydrocarbons levels are appropriate and does not adjust operation of the ICE11. FIG.2schematically illustrates a circuit diagram showing one example circuit layout of circuit17. Signals from the oxygen sensor are provided to an input port (Input-1) and sent to a switch gate (Q2). In one embodiment, the switch is a gated metal-oxide semiconductor field-effect transistor (MOSFET) that is used to control the added voltage to the signal provided to by the input port. The switch creates an on/off voltage pulse that is sent to an output (output-2). A diode (D2) is used to connect the input (input-1) and the output (output-2) in the direction of the output (output-2). The circuit can be powered from the battery16and, in order to achieve a selected voltage, can use a voltage regulator (IC4) one or more capacitors (C1, C2) to stabilize the voltage, one or more resistors (R10-R16) and one or more potentiometers (R9, R12) to step down and adjust the voltage. FIG.3schematically illustrates a diagram illustrating connection of the circuit17into the wire harness15connecting the oxygen sensor14to the electronic control unit13. The connector21ais connected to closest to the ECU13, whereas the connector21bis connected closest to the oxygen sensor14. An input signal (I) travels to connector21band is sent from a tap50through port22bto circuit17and to a diode51. The interface circuit17then adds voltage to signal (I). This increased voltage signal (FIG.2. Output-2) is sent through port22aand a tap52. An output signal (0) is provided through connector21aand on to the ECU13.FIG.4is an example waveform illustrating a difference between the input signal (I) and the output signal (O). Various embodiments of the invention have been described above for purposes of illustrating the details thereof and to enable one of ordinary skill in the art to make and use the invention. The details and features of the disclosed embodiment[s] are not intended to be limiting, as many variations and modifications will be readily apparent to those of skill in the art. Accordingly, the scope of the present disclosure is intended to be interpreted broadly and to include all variations and modifications coming within the scope and spirit of the appended claims and their legal equivalents. | 5,834 |
11859574 | DETAILED DESCRIPTION OF THE DISCLOSURE Hereinafter, one embodiment of a method of controlling an engine, and an engine system is described with reference to the accompanying drawings. The engine, the engine system, and the engine control method described herein are merely illustration. FIG.1is a view illustrating the engine system.FIG.2is a view illustrating a configuration of a combustion chamber of the engine. An intake side and an exhaust side illustrated inFIG.1are opposite from the intake side and the exhaust side illustrated inFIG.2.FIG.3is a block diagram illustrating a control device for the engine. The engine system includes an engine1. The engine1includes cylinders11, and is a four-stroke engine in which an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke are repeated in each cylinder11. The engine1is mounted on a four-wheeled automobile, and the automobile travels according to the operation of the engine1. Fuel of the engine1is gasoline in this example. (Configuration of Engine) The engine1is provided with a cylinder block12and a cylinder head13. The cylinder head13is placed on the cylinder block12. A plurality of cylinders11are formed inside the cylinder block12. The engine1is a multi-cylinder engine. InFIG.1, only one cylinder11is illustrated. A piston3is inserted into each cylinder11. The piston3is coupled to a crankshaft15through a connecting rod14. The piston3reciprocates inside the cylinder11. The piston3, the cylinder11, and the cylinder head13define a combustion chamber17. As illustrated in the lower part ofFIG.2, a lower surface of the cylinder head13(i.e., a ceiling of the cylinder11) is constituted by a sloped surface1311and a sloped surface1312. The sloped surface1311is a slope on a side of an intake valve21(described later), and inclines upwardly toward a central part of the ceiling of the cylinder11. The sloped surface1312is a slope on a side of an exhaust valve22(described later), and inclines upwardly toward the central part of the ceiling of the cylinder11. The ceiling of the cylinder11is a so-called pentroof type. The cylinder head13is formed with intake ports18for the cylinders11such that each intake port18communicates with the inside of the corresponding cylinder11. Although detailed illustration is omitted, the intake port18is a so-called tumble port. That is, the intake port18has a shape which generates a tumble flow inside the cylinder11. The pentroof ceiling of the cylinder11and the tumble port generate the tumble flow inside the cylinder11. Each intake port18is provided with the intake valve21. The intake valve21opens and closes the intake port18. A valve operating mechanism opens and closes the intake valve21at a given timing. The valve operating mechanism may be a variable valve operating mechanism which varies a valve timing and/or a valve lift. As illustrated inFIG.3, the valve operating mechanism includes an intake S-VT (Sequential-Valve Timing)23of an electric type or a hydraulic type. The intake S-VT23continuously changes a rotational phase of an intake camshaft within a given angle range. A valve opening period of the intake valve21does not change. The cylinder head13is formed with exhaust ports19for the cylinders11such that each exhaust port19communicates with the inside of the corresponding cylinder11. Each exhaust port19is provided with the exhaust valve22. The exhaust valve22opens and closes the exhaust port19. A valve operating mechanism opens and closes the exhaust valve22at a given timing. The valve operating mechanism may be a variable valve operating mechanism which varies a valve timing and/or a valve lift. As illustrated inFIG.3, the valve operating mechanism includes an exhaust S-VT24of an electric type or a hydraulic type. The exhaust S-VT24continuously changes a rotational phase of an exhaust camshaft within a given angle range. A valve opening period of the exhaust valve22does not change. Injectors6are attached to the cylinder head13for the respective cylinders11. As illustrated inFIG.2, each injector6is provided to the central part of the cylinder11in the plan view (at or near a center axis X1of the cylinder). In detail, the injector6is disposed in a valley part of the pentroof where the sloped surface1311and the sloped surface1312intersect with each other. The injector6directly injects fuel into the cylinder11. The injector6is one example of a fuel injector, and is of a multiple nozzle hole type having a plurality of nozzle holes (not illustrated in detail). As illustrated by two-dot chain lines inFIG.2, the injector6injects fuel radially outwardly from the central part to a peripheral part of the cylinder11. Although, in this example, the injector6has ten nozzle holes which are circumferentially disposed at an equal angle, the number of nozzle holes and the positions thereof are not particularly limited to this configuration. The injector6is connected to a fuel supply system61. The fuel supply system61is comprised of a fuel tank63which stores fuel, and a fuel supply passage62which couples the fuel tank63to the injector6. A fuel pump65and a common rail64are interposed in the fuel supply passage62. The fuel pump65pumps fuel to the common rail64. The fuel pump65is a plunger-type pump driven by the crankshaft15in this example. The common rail64stores at a high fuel pressure the fuel pumped from the fuel pump65. When the injector6is valve-opened, the fuel stored in the common rail64is injected into the cylinder11from the nozzle holes of the injector6. The pressure of the fuel supplied to the injector6may be changed according to the operating state of the engine1. Note that the configuration of the fuel supply system61is not limited to the configuration described above. Spark plugs25are attached to the cylinder head13for the respective cylinders11. Each spark plug25forcibly ignites a mixture gas inside the cylinder11. Although detailed illustration is omitted, a center electrode and a ground electrode of the spark plug25are positioned at the central part of the cylinder11in the plan view, near the ceiling. As illustrated inFIGS.1and3, the spark plug25is electrically connected to an ignition device7. The ignition device7applies voltage between the electrodes of the spark plug25to cause an electric discharge (arc discharge) so as to ignite the mixture gas inside the cylinder11. The ignition device7also causes the spark plug25to discharge the electricity when the mixture gas is not ignited, and detects a parameter related to a current value of an electric-discharge channel, which is generated between the electrodes in the electric discharge (details will be described later). The detected parameter is used to estimate a state of flow inside the cylinder11. The configuration of the ignition device7will be described later. The engine1is connected at one side to an intake passage40. The intake passage40communicates with the intake ports18of the cylinders11. Air to be introduced into the cylinders11flows through the intake passage40. The intake passage40is provided at its upstream-end part with an air cleaner41. The air cleaner41filters the air. The intake passage40is provided, near its downstream end, with a surge tank42. A part of the intake passage40downstream of the surge tank42constitutes independent passages branching for the respective cylinders11. Downstream ends of the independent passages are connected to the intake ports18of the cylinders11, respectively. The intake passage40is provided, between the air cleaner41and the surge tank42, with a throttle valve43. The throttle valve43adjusts the opening of the valve to control an amount of air to be introduced into the cylinder11. The engine1is provided with a swirl generator which generates a swirl flow inside the cylinders11. Although detailed illustration is omitted, the swirl generator has a swirl control valve56attached to the intake passage40. The intake passage40includes a first intake passage18aand a second intake passage18b(seeFIG.2) which are parallelly provided downstream of the surge tank42, and the swirl control valve56is provided to the second intake passage18b. The swirl control valve56is an opening control valve which is capable of choking a cross-section of the second intake passage18b. When the opening of the swirl control valve56is small, a flow rate of the intake air flowing into the cylinder11from the first intake passage18ais relatively large, and a flow rate of the intake air flowing into the cylinder11from the second intake passage18bis relatively small, which increases the swirl flow inside the cylinder11. On the other hand, when the opening of the swirl control valve56is large, the flow rate of the intake air flowing into the cylinder11from the first intake passage18aand the flow rate of the intake air flowing from the second intake passage18bare substantially equal, which reduces the swirl flow inside the cylinder11. When the swirl control valve56is fully opened, the swirl flow is not generated. Note that as illustrated by white arrows inFIG.2, the swirl flow circles in the counterclockwise direction. Note that instead of generating the swirl flow by the swirl control valve56, the intake port18of the engine1may be configured to be a helical port capable of generating the swirl flow. The engine1is connected at the other side to an exhaust passage50. The exhaust passage50communicates with the exhaust ports19of the cylinders11. The exhaust passage50is a passage through which exhaust gas discharged from the cylinders11flows. Although detailed illustration is omitted, an upstream part of the exhaust passage50constitutes independent passages branching for the respective cylinders11. Upstream ends of the independent passages are connected to the exhaust ports19of the cylinders11, respectively. The exhaust passage50is provided with an exhaust gas purification system having a plurality of catalytic converters. An upstream catalytic converter includes a three-way catalyst511and a GPF (Gasoline Particulate Filter)512. A downstream catalytic converter includes a three-way catalyst513. Note that the exhaust gas purification system is not limited to the illustrated configuration. For example, the GPF may be omitted. Moreover, the catalytic converter is not limited to the one including the three-way catalyst. Further, the disposed order of the three-way catalyst and the GPF may be changed suitably. An exhaust gas recirculation (EGR) passage52is connected between the intake passage40and the exhaust passage50. The EGR passage52is a passage through which a part of exhaust gas recirculates to the intake passage40. An upstream end of the EGR passage52is connected to a part of the exhaust passage50between the upstream and downstream catalytic converters. A downstream end of the EGR passage52is connected to a part of the intake passage40between the throttle valve43and the surge tank42. The EGR passage52is provided with an EGR cooler53of a water-cooled type. The EGR cooler53cools exhaust gas. The EGR passage52is also provided with an EGR valve54. The EGR valve54controls a flow rate of exhaust gas flowing through the EGR passage52. The EGR valve54changes its opening to control a recirculating amount of the cooled exhaust gas. As illustrated inFIG.3, the control device for the engine1is provided with an ECU (Engine Control Unit)10to operate the engine1. The ECU10is a controller based on a well-known microcomputer, and includes a processor (e.g., a central processing unit (CPU))101which executes a program, memory102which is comprised of, for example, RAM (Random Access Memory) and ROM (Read Only Memory), and stores the program and data, and an interface (I/F) circuit103which inputs and outputs an electric signal. The ECU10is one example of a “controller.” As illustrated inFIGS.1and3, various kinds of sensors SW1-SW9are connected to the ECU10. The sensors SW1-SW9output signals to the ECU10. The sensors include the following sensors. An airflow sensor SW1is provided to the intake passage40downstream of the air cleaner41, and measures the flow rate of air flowing through the intake passage40. An intake temperature sensor SW2is provided to the intake passage40downstream of the air cleaner41, and measures the temperature of the air flowing through the intake passage40. An intake pressure sensor SW3is attached to the surge tank42, and measures the pressure of the air to be introduced into the cylinder11. An in-cylinder pressure sensor SW4is attached to the cylinder head13for each cylinder11, and measures the pressure inside the cylinder11. A water temperature sensor SW5is attached to the engine1, and measures the temperature of coolant. A crank angle sensor SW6is attached to the engine1, and measures a rotational angle of the crankshaft15. An accelerator opening sensor SW7is attached to an accelerator pedal mechanism, and measures an accelerator opening corresponding to an operation amount of an accelerator pedal. An intake cam angle sensor SW8is attached to the engine1, and measures a rotational angle of the intake camshaft. An exhaust cam angle sensor SW9is attached to the engine1, and measures a rotational angle of the exhaust camshaft. The ECU10determines the operating state of the engine1based on the signals of the sensors SW1-SW9, and also calculates a control amount of each device based on a given control logic stored in the memory102. The control logic includes calculating a target amount and/or the control amount by using a map stored in the memory102. The ECU10outputs electric signals related to the calculated control amounts to the injectors6, the spark plugs25, the intake S-VT23, the exhaust S-VT24, the fuel supply system61, the throttle valve43, the EGR valve54, and the swirl control valve56. The ECU10electrically connected to the various sensors and devices constitutes a plurality of functional blocks to operate the engine1, which will be described later. (Configuration of Ignition Device) FIG.4illustrates a configuration of the ignition device7. The ignition device7applies voltage between a center electrode251and a ground electrode252of the spark plug25so as to cause the electric discharge inside the cylinder11. The ignition device7includes an ignition coil70having a primary coil70a, a secondary coil70c, and an iron core70b. The ignition device7is also provided with a capacitor72, a transistor73, an energy generator74, and an ignition controller75. The center electrode251is connected to the secondary coil70cof the ignition coil70, and the ground electrode252is connected to the ground. When a secondary voltage applied between the electrodes by the secondary coil70creaches a voltage required for electrical breakdown, the electric discharge occurs at a gap between the center electrode251and the ground electrode252. One end of the primary coil70ais connected to the capacitor72. The capacitor72stores electrical energy to supply a primary current to the primary coil70a. The energy generator74includes a power source, and charges the capacitor72. The other end of the primary coil70ais connected to a collector of the transistor73. The transistor73switches between supplying or not supplying the primary current to the ignition coil70. As described above, one end of the secondary coil70cis connected to the center electrode251, and the other end is connected to the ignition controller75. The ignition controller75controls the energy generator74and the transistor73so that the spark plug25ignites the mixture gas inside the cylinder11at a given timing. Moreover, the ignition controller75can measure the secondary voltage applied between the electrodes of the spark plug25by the secondary coil70c, and a secondary current flown from the secondary coil70cto the spark plug25. As described above, the ignition device7causes the spark plug25to discharge the electricity when the mixture gas is not ignited, and detects the parameter related to the current value at the time of the electric discharge. (Operation Control for Engine) Next, operation control for the engine1by the ECU10is described. The engine1is a spark-ignition engine. The injector6injects fuel into the cylinder11during an intake stroke or a compression stroke by an amount corresponding to the operating state of the engine1to form mixture gas inside the cylinder11, and the spark plug25ignites the mixture gas at a given timing near a compression top dead center (TDC) to combust the mixture gas. The engine1generates a turbulence inside the cylinder11to improve fuel efficiency. When the turbulence is generated inside the cylinder11, combustion speed increases. In detail, the engine1is provided with the cylinder11with the pentroof ceiling, and the intake port18of the tumble-port type. The intake air introduced into the cylinder11generates a tumble flow. The engine1also includes the swirl control valve56. When the swirl control valve56is closed, the intake air introduced into the cylinder11generates a swirl flow. By the tumble flow and the swirl flow being combined together, an oblique flow in which a tumble vortex and a swirl vortex are combined, is generated inside the cylinder11. Here, the state of the intake flow inside the cylinder11is not the same in every cycle, but may vary depending on various factors. The change in the state of the intake flow may lead to the change in the combustion speed. When the combustion speed varies between cycles, combustion variation of the engine1may be caused. The engine system and the method of controlling the engine1disclosed herein reduce the combustion variation of the engine1by reducing the variations in the combustion speed between the cycles. In more detail, in this engine system, the state of the flow inside the cylinder11is estimated every cycle, as well as the spark plug25operating inside the cylinder11(performing a supplemental ignition) as needed based on the estimated flowing state. FIG.5is a block diagram illustrating a configuration of the control device for the engine1, which executes the control for reducing the combustion variation.FIG.5illustrates functional blocks of the ECU10. The ECU10includes a main fuel injection module81and a main ignition control module82executed by the processor101to perform their respective functions. These modules are stored in the memory102as software modules. The main fuel injection module81sets an injection amount and an injection timing of main fuel corresponding to a demanded torque of the engine1, and causes the injector6to inject the main fuel. The main ignition control module82causes the spark plug25to ignite the mixture gas inside the cylinder11at a given timing (i.e., a main ignition) after the injection of the main fuel. The ECU10also includes a determination module83and a supplemental ignition control module84. As will be described later, the determination module83determines the flowing state inside the cylinder11based on the parameters detected by using the ignition device7and the spark plug25. The supplemental ignition control module84causes the spark plug25to carry out electric discharge inside the cylinder as needed before the main ignition of the mixture gas, based on the flowing state inside the cylinder11determined by the determination module83, and generates a hot plasma. Below, the estimation of the flowing state inside the cylinder11, which is executed by the engine control device illustrated inFIG.5, is described. Then, injection control of the supplemental ignition based on the estimated flowing state is described. (Estimation of Flowing State) FIG.6is a view illustrating the center of the tumble vortex in an early half of a compression stroke and the flowing state inside the cylinder11in a latter half of the compression stroke. Chart601inFIG.6illustrates the flowing state inside the cylinder11in the early half of the compression stroke, where the center of the tumble vortex is near the piston3inside the cylinder11. Chart604illustrates the flowing state inside the cylinder11in the latter half of the compression stroke, in which the crank angle progressed from the state of chart601. Similarly, chart602illustrates the flowing state inside the cylinder11in the early half of the compression stroke, where the center of the tumble vortex is at the middle between the piston3and the ceiling inside the cylinder11. Chart605illustrates the flowing state inside the cylinder11in the latter half of the compression stroke, in which the crank angle progressed from the state of chart602. Moreover, chart603illustrates the flowing state inside the cylinder11in the early half of the compression stroke, where the center of the tumble vortex is near the ceiling inside the cylinder11. Chart606illustrates the flowing state inside the cylinder11in the latter half of the compression stroke, in which the crank angle progressed from the state of chart603. Note that the early half and the latter half of the compression stroke correspond to the early half and the latter half when the compression stroke is equally divided, respectively. First, as illustrated in chart602, when the center of the tumble vortex inside the cylinder11is located around the center of the combustion chamber17in the side view, the rotating flow is maintained also in the latter half of the compression stroke as indicated by a solid arrow in chart605. As a result, the turbulence is uniform or substantially uniform entirely inside the cylinder. In this case, the flame is uniformly or substantially uniformly propagated from around the center toward the peripheral part inside the cylinder11. Since the propagation of the flame is accelerated by the turbulence inside the cylinder11, the combustion speed is comparatively high. As illustrated in chart601, when the center of the tumble vortex deviates downward inside the cylinder11in the side view, the vortex center contacts the top surface of the piston3and a lower half of the tumble vortex is broken in the latter half of the compression stroke as illustrated in chart604. Accordingly, as indicated by an arrow in chart604, the flow inside the cylinder11becomes a one-way flow from the intake valve21toward the exhaust valve22. Hereinafter, this one-way flow is referred to as a “forward one-way flow.” When the flow inside the cylinder11is the forward one-way flow, the turbulence inside the cylinder11is uneven. In detail, while the turbulence in an area on the exhaust-valve side is strong, the turbulence in an area on the intake-valve side (the area surrounded by a one-dot chain line in chart604) is weak. In such a case, although the flame generated by the ignition of the mixture gas at the central part of the cylinder11is easily propagated to the exhaust-side area, the propagation toward the intake-side area is difficult. The combustion speed in the case of chart604is lower than the case of chart605. As illustrated in chart603, when the center of the tumble vortex deviates upward inside the cylinder11in the side view, the vortex center contacts the ceiling of the cylinder11and an upper half of the tumble vortex is broken in the latter half of the compression stroke as illustrated in chart606. Accordingly, as indicated by arrows in chart606, the flow inside the cylinder11becomes a one-way flow from the exhaust valve22toward the intake valve21. Hereinafter, this one-way flow is referred to as a “backward one-way flow.” When the flow inside the cylinder11is the backward one-way flow, the turbulence inside the cylinder11is uneven. In detail, while the turbulence in the area on the intake-valve side is strong, the turbulence in the area on the exhaust-valve side (the area surrounded by a one-dot chain line in chart606) is weak. In such a case, although the flame is easily propagated toward the intake-side area, the propagation toward the exhaust-side area is difficult. The combustion speed in the case of chart606is lower than the case of chart605. In the engine system, the ignition device7detects the flowing state inside the cylinder11. In detail, the ignition device7causes the electric discharge inside the cylinder11at a timing when the mixture gas is not ignited, and detects a period of time for which the electric discharge continues (discharge duration). The determination module83estimates the intensity of the flow around the spark plug25based on the detected discharge duration, and determines the center of the tumble vortex based on the estimated flow intensity. FIG.7illustrates a time-series change701in the voltage and a time-series change702in the current between the electrodes of the spark plug25at different flow intensities around the spark plug25. When the spark plug25is applied with energy and voltage is applied between the electrodes, an electric-discharge channel is formed between the center electrode251and the ground electrode252(see charts703and704). As the intensity of the flow around the spark plug25increases, the electric-discharge channel is blown and extended by the flow. The extension of the electric-discharge channel increases the resistance between the electrodes, which accelerates a decrease in the voltage applied between the electrodes. As the intensity of the flow around the spark plug25increases, a period of time required for the consumption of the energy applied to the spark plug25(i.e., the discharge duration) becomes shorter. In more detail, as indicated by solid lines inFIG.7, when there is no flow around the spark plug25, the electric-discharge channel is hardly extended (see chart703), and thus, the discharge duration is long. Since the electric-discharge channel extends as the intensity of the flow around the spark plug25increases (see chart704), the discharge duration becomes shorter as illustrated by broken lines and dotted lines in charts701and702. That is, the discharge duration of the current between the electrodes of the spark plug25is in proportion to the intensity of the flow around the spark plug25. When the ignition device7detects the discharge duration, the determination module83can estimate the intensity of the flow (i.e., a flow velocity) around the spark plug25. FIG.8illustrates a relationship between the discharge duration detected by the ignition device7, and the center of the tumble vortex inside the cylinder11. Chart800ofFIG.8illustrates a relationship between the discharge duration and a flow velocity Vp around the spark plug25. As described above, the discharge duration is in proportion to the flow velocity Vp, and the flow velocity Vp increases as the discharge duration is shorter, and the flow velocity Vp decreases as the discharge duration is longer. As illustrated in chart802ofFIG.8, when the center of the tumble vortex is at the middle between the piston3and the ceiling inside the cylinder11in the early half of the compression stroke, the center of the vortex is separated from the spark plug25to some extent. Therefore, the flow velocity Vp around the spark plug25is between V1and V2. On the other hand, as illustrated in chart801, when the center of the tumble vortex is near the piston3in the early half of the compression stroke, the center of the vortex is largely separated from the spark plug25. Therefore, the flow velocity Vp around the spark plug25is higher than V1. Moreover, as illustrated in chart803, when the center of the tumble vortex is near the ceiling in the early half of the compression stroke, the center of the vortex is near the spark plug25. Therefore, the flow velocity Vp around the spark plug25is lower than V2. The tumble vortex which is formed inside the cylinder11mainly by a tumble flow, becomes stable and the center of the tumble vortex is defined during the compression stroke after the intake valve21is closed. Therefore, the center of the tumble vortex can be estimated by the spark plug25carrying out the electrical discharge (a second electric discharge described later) and the ignition device7detecting the discharge duration (a second discharge duration described later) in the early half of the compression stroke. If the discharge duration is shorter than a first threshold corresponding to the velocity V1, the center of the tumble vortex can be estimated to be near the piston3. If the discharge duration is longer than a second threshold corresponding to the velocity V2, the center of the tumble vortex can be estimated to be near the ceiling. If the discharge duration is between the first threshold and the second threshold, the center of the tumble vortex can be estimated to be at the middle of the combustion chamber17in the side view. FIG.9is a view illustrating a relationship between the center of the swirl vortex during the intake stroke and the flowing state inside the cylinder11in the latter half of the compression stroke. Chart901ofFIG.9illustrates the flowing state inside the cylinder11when the center of the swirl vortex deviates to the exhaust-valve side inside the cylinder11during the intake stroke. Chart904illustrates a propagation state of the flame after the latter half of the compression stroke, in which the crank angle progressed from the state of chart901. Similarly, chart902illustrates the flowing state inside the cylinder11when the center of the swirl vortex is almost on the axis of the cylinder11at the central part of the cylinder11during the intake stroke. Chart905illustrates the propagation state of the flame after the latter half of the compression stroke, in which the crank angle progressed from the state of chart902. Moreover, chart903illustrates the flowing state inside the cylinder11when the center of the swirl vortex deviates to the intake-valve side inside the cylinder11during the intake stroke. Chart906illustrates the flowing state inside the cylinder in the latter half of the compression stroke, in which the crank angle progressed from the state of chart903. First, as illustrated in chart902, when the center of the swirl vortex inside the cylinder11is located on the axis at the central part of the cylinder11in the plan view, the center of the swirl vortex is located near the axis also in the latter half of the compression stroke. The turbulence inside the cylinder11is uniform or substantially uniform entirely inside the cylinder11. When the spark plug25ignites the mixture gas at the central part of the cylinder11, the flame is propagated from the central part toward the peripheral part inside the cylinder11while being curved in the circumferential direction by the swirl vortex as indicated by broken arrows in chart905. The flame is uniformly or substantially uniformly propagated from around the center toward the peripheral part inside the cylinder11. Since the propagation of the flame is accelerated by the turbulence inside the cylinder11, the combustion speed is comparatively high. As illustrated in chart901, when the center of the swirl vortex deviates to the exhaust-valve side in the plan view, the center of the swirl vortex deviates from the center of the cylinder11. The turbulence inside the cylinder11becomes uneven entirely inside the cylinder11. Moreover, when the spark plug25ignites the mixture gas at the central part of the cylinder11near the compression TDC in the latter half of the compression stroke, the flame is propagated from the central part toward the peripheral part inside the cylinder11while being curved (turned) in the circumferential direction by the swirl vortex as indicated by broken arrows in Chart904. Here, the flow velocity of the swirl vortex is higher as being separated from the center of the swirl vortex (see concentric circles in chart904). That is, the flow velocity of the swirl vortex is relatively high on the intake-valve side which is far from the center of the swirl vortex. Although the flame propagating from the central part of the cylinder11to the exhaust-valve side propagates radially outwardly while being curved in the circumferential direction, the flame propagating from the central part of the cylinder11to the intake-valve side is intensely curved by the swirl vortex at the high flow velocity, thus the radially outward propagation being difficult. As a result, the flame propagation in the intake-side area is difficult as indicated by the one-dot chain line in chart904. In this case, the combustion speed is lower than the case of chart905. As illustrated in chart903, also when the center of the swirl vortex deviates to the intake-valve side in the plan view, the center of the swirl vortex deviates from the center of the cylinder11. The turbulence inside the cylinder11becomes uneven entirely inside the cylinder11. Moreover, when the spark plug25ignites the mixture gas at the central part of the cylinder11near the compression TDC in the latter half of the compression stroke, the flame is propagated from the central part toward the peripheral part inside the cylinder11while being curved in the circumferential direction by the swirl vortex as indicated by broken arrows in chart906. Here, the direction from the central part to the intake-valve side of the cylinder11is the direction opposite from the flow of the swirl vortex in the counterclockwise direction indicated by solid lines in chart906. As a result, although the flame propagating from the central part of the cylinder11to the exhaust-valve side propagates radially outwardly while being curved in the circumferential direction, the flame propagating from the central part of the cylinder11to the intake-valve side is pushed back by the flow of the swirl vortex, thus the radially outward propagation being difficult. As a result, the flame propagation in the intake-side area is difficult as indicated by the one-dot chain line in chart906. In this case, the combustion speed is lower than the case of chart905. FIG.10illustrates a relationship between the duration of the electric discharge detected by the ignition device7, and the center of the swirl vortex inside the cylinder11. Chart1000ofFIG.10illustrates a relationship between the discharge duration and the flow velocity around the spark plug25. The intake air is flown into the cylinder11mainly from the first intake passage18ato generate the swirl flow. As illustrated in chart1002ofFIG.10, a flow-velocity distribution occurs inside the cylinder11during the intake stroke by the intake air which is introduced mainly from the first intake passage18a. The center of the swirl vortex is located on the axis around the central part of the cylinder11when the velocity distribution during the intake stroke is as illustrated in chart1002, in which the flow velocity is the maximum at a certain position in the radial direction between the central part and a liner of the cylinder11, and the flow velocity decreases toward the central part and toward the liner from the certain position. In this case, the flow velocity around the spark plug25is between V3and V4. On the other hand, as illustrated in chart1001, in a case of the flow-velocity distribution in which the flow velocity near the liner is extremely high during the intake stroke, the center of the swirl vortex deviates to the exhaust-valve side. In this case, the flow velocity around the spark plug25is lower than V4. Moreover, as illustrated in chart1003, when the maximum flow velocity is comparatively low, and a kurtosis of the flow velocity is small in the flow-velocity distribution during the intake stroke, the center of the swirl vortex deviates to the intake-valve side. In this case, the flow velocity around the spark plug25is higher than V3. The swirl vortex formed mainly by a swirl flow inside the cylinder11becomes stable during the intake stroke between the opening and closing of the intake valve21. The ignition device7causes the spark plug25to carry out the electrical discharge (a first electric discharge described later) and detects the discharge duration (a first discharge duration described later) during the intake stroke. In detail, the flow of the intake air easily changes for a certain period from the opened timing of the intake valve21. The swirl vortex stabilizes after the certain period from the opening of the intake valve21, before the closing of the intake valve21. The ignition device7causes the spark plug25to carry out the electric discharge after a given period (a time constant Δt described later) from the opening of the intake valve21, and detects the discharge duration. The determination module83can determine that the center of the swirl vortex deviates to the intake-valve side when the discharge duration is shorter than the first threshold corresponding to the velocity V3. The determination module83can determine that the center of the swirl vortex deviates to the exhaust-valve side when the discharge duration is longer than the second threshold corresponding to the velocity V4. The determination module83can determine that the center of the swirl vortex is on the axis at the central part of the cylinder11when the discharge duration is between the first threshold and the second threshold. Note that the velocity V3corresponding to the first threshold and the velocity V1described above are not necessarily the same. Similarly, the velocity V4corresponding to the second threshold and the velocity V2described above are not necessarily the same. (Supplemental Ignition Control) FIG.11is a time chart illustrating the timing of the fuel injection by the injector6, and the timings of the electric discharge, the supplemental ignition, and the main ignition by the spark plug25. The crank angle progresses from the left to the right inFIG.11. As described above, when the center of the tumble vortex and/or the swirl vortex deviate due to the variation in the intake flow, the area with a small turbulence and/or the area with difficulty in the flame propagation are generated inside the cylinder11. The supplemental ignition makes the mixture gas increased in the temperature by the hot plasma be positioned in the area with the small turbulence and/or the area with the difficulty in the flame propagation so as to accelerate the flame propagation toward such specific areas. First, the main fuel injection module81causes the injector6to inject the main fuel inside the cylinder11in a period during the intake stroke between the opening and closing of the intake valve21(see a main fuel injection1104). The main fuel is spread inside the cylinder11by the flow, and the mixture gas is generated inside the cylinder11. As illustrated in chart1102, the determination module83causes the ignition device7and the spark plug25to carry out a first electric discharge1105at a timing during the intake stroke after the given time constant Δt passes from the opening of the intake valve21. The first electric discharge1105is the electric discharge which is performed when the mixture gas is not ignited. The ignition device7detects the first discharge duration of the first electric discharge. The determination module83estimates the center of the swirl vortex based on the first discharge duration detected in the first electric discharge1105. The determination module83also causes the ignition device7and the spark plug25to carry out a second electric discharge1106, for example, in the early half of the compression stroke after the closing of the intake valve21. Also the second electric discharge1106is the electric discharge which is performed when the mixture gas is not ignited. The ignition device7detects the second discharge duration of the second electric discharge. The determination module83estimates the center of the tumble vortex based on the second discharge duration detected in the second electric discharge1106. When both of the first discharge duration and the second discharge duration detected by the ignition device7are between the first threshold and the second threshold, the center of the tumble vortex is located at the middle between the piston3and the ceiling inside the cylinder11, and the center of the swirl vortex is located on the axis at the central part of the cylinder11. In this case, the injection of the supplemental ignition is unnecessary. As illustrated in chart1102ofFIG.11, the supplemental ignition control module84suspends the supplemental ignition, and the main ignition control module82causes the spark plug25to ignite the mixture gas at the given timing near the compression TDC in the latter half of the compression stroke (see a main ignition1107ofFIG.11). In this case, since the centers of the swirl vortex and the tumble vortex are located at the central part of the cylinder11when seen in a plan view and side view, respectively, the turbulence is uniform or substantially uniform entirely inside the cylinder11. The flame uniformly or substantially uniformly propagates from the central part toward the peripheral part of the cylinder11. The combustion speed is comparatively high. Next, the case where the second discharge duration detected by the ignition device7is below (shorter than) the first threshold is described. In this case, the center of the tumble vortex is near the piston3inside the cylinder11, and the forward one-way flow is generated inside the cylinder11in the latter half of the compression stroke. As illustrated in chart1101ofFIG.11, the supplemental ignition control module84causes the spark plug25to carry out a first supplemental ignition1108. The spark plug25carries out the first supplemental ignition1108at a first operation timing, for example, in the early half of the compression stroke or the latter half of the compression stroke. As illustrated inFIG.12, by the ignition device7applying the energy to the spark plug25, the arc discharge occurs between the center electrode251and the ground electrode252of the spark plug25(i.e., the supplemental ignition). The hot plasma thus generated inside the cylinder11rides on the flow inside the cylinder11to be carried. FIG.13is a view illustrating the flow change and distribution of the hot plasma inside the cylinder11when the center of the tumble vortex is near the piston3inside the cylinder11. As described above, when the center of the tumble vortex is near the piston3, the center of the vortex contacts the top surface of the piston3and the lower half of the tumble vortex is broken as the piston3ascends as illustrated in P1301, P1302, P1303, and P1304, in this order. Accordingly, as indicated by a black arrow in P1305, the flow inside the cylinder11becomes the forward one-way flow from the intake valve21toward the exhaust valve22in the latter half of the compression stroke. The spark plug25carries out the first supplemental ignition at a relatively early timing (P1303) during the compression stroke, and since the pressure inside the cylinder11is not relatively high at that early timing, the hot plasma generated inside the cylinder11rides on the tumble vortex to be carried from the exhaust-valve side to the intake-valve side (see hatched areas in P1303, P1304, and P1305) before the vortex is broken. As a result, the mixture gas around the intake valve can be high in the temperature. After the first supplemental ignition1108, the main ignition control module82causes the spark plug25to ignite the mixture gas at the given timing near the compression TDC in the latter half of the compression stroke (see the main ignition1107in chart1101). Although the flame is difficult to be propagated toward the intake-valve side due to the forward one-way flow, since the temperature of the mixture gas is high on the intake-valve side, the flame propagation toward the intake-valve side is accelerated. Accordingly, the combustion speed is increased to the extent similar to the case where the discharge duration is between the first threshold and the second threshold. Therefore, combustion variation of the engine1is reduced. Next, the case where the second discharge duration detected by the ignition device7is above (longer than) the second threshold is described. In this case, the center of the tumble vortex is near the ceiling inside the cylinder11, and the backward one-way flow is generated inside the cylinder11in the latter half of the compression stroke. As illustrated in chart1103inFIG.11, the supplemental ignition control module84causes the spark plug25to perform a second supplemental ignition1109. The spark plug25performs the second supplemental ignition1109at a second operation timing in the latter half of the compression stroke. The timing of the second supplemental ignition1109is later than the timing of the first supplemental ignition1108. FIG.14is a view illustrating the flow change and distribution of the hot plasma inside the cylinder11when the center of the tumble vortex is near the ceiling inside the cylinder11. As described above, when the center of the tumble vortex is near the ceiling, the center of the vortex contacts the ceiling and the upper half of the tumble vortex is broken as the piston3ascends as illustrated in P1401, P1402, P1403, and P1404, in this order. Accordingly, as indicated by black arrows in P1405, the flow inside the cylinder11becomes the backward one-way flow from the exhaust valve22toward the intake valve21in the latter half of the compression stroke. The spark plug25carries out the second supplemental ignition in the latter half of the compression stroke (see P1404). Since the pressure inside the cylinder11is high in the latter half of the compression stroke, the hot plasma generated inside the cylinder11stays at the central part inside the cylinder11by receiving the high compression pressure, as well as flowing to the exhaust-valve side where the flow is relatively weak (see hatched areas in P1404and P1405). As a result, the mixture gas at the high temperature can be positioned around the exhaust valve. After the second supplemental ignition1109, the main ignition control module82causes the spark plug25to ignite the mixture gas at the given timing near the compression TDC in the latter half of the compression stroke (see the main ignition1107in chart1103). Although the flame is difficult to be propagated toward the exhaust-valve side due to the backward one-way flow, since the temperature of the mixture gas is high on the exhaust-valve side, the flame propagation toward the exhaust-valve side is accelerated. Accordingly, the combustion speed is increased to the extent similar to the case where the discharge duration is between the first threshold and the second threshold. Therefore, combustion variation of the engine1is reduced. Therefore, by performing the supplemental ignition according to the flowing state inside the cylinder11, even when the center of the tumble vortex varies due to the variation in the state of the intake flow between the cycles, the ECU10can make the combustion speed to be the same or substantially the same. Thus, combustion variation can be reduced. Next, the case where the first discharge duration detected by the ignition device7is below (shorter than) the first threshold is described. In this case, the center of the swirl vortex is deviated to the intake-valve side inside the cylinder11. As illustrated in chart1101ofFIG.11, the supplemental ignition control module84causes the spark plug25to perform the first supplemental ignition1108. The spark plug25carries out the first supplemental ignition1108at the first operation timing, for example, in the early half of the compression stroke or the latter half of the compression stroke. P1501and P1502inFIG.15are views illustrating the flow change and distribution of the hot plasma inside the cylinder11when the center of the swirl vortex is deviated to the intake-valve side. When the center of the swirl vortex is deviated to the intake-valve side, as illustrated in P1501, the kurtosis of the flow velocity distribution inside the cylinder11during the compression stroke is low. Therefore, an area where the flow velocity is extremely high does not exist. The hot plasma generated by the spark plug25at the central part inside the cylinder11in the early or latter half of the compression stroke after the second electric discharge, rides on the flow indicated by solid arrows inFIG.15to be carried radially outwardly, as well as being carried in the circumferential direction along the liner (see broken arrows inFIG.15). Since the supplemental-ignition timing is relatively advanced, a long period of time is spent for the hot plasma to be carried to the intake-valve side. As a result, the temperature of the mixture gas on the intake-valve side is increased at the ignition timing (P1502). After the first supplemental ignition, the main ignition control module82causes the spark plug25to ignite the mixture gas at the given timing near the compression TDC in the latter half of the compression stroke (see the main ignition1107of chart1101). As described above, since the flame is prevented from propagating radially outwardly by the swirl vortex with the deviated center, the propagation toward the intake-valve side is difficult. However, since the temperature of the mixture gas on the intake-valve side is high, the flame propagation toward the intake-valve side is accelerated. Accordingly, the combustion speed is increased to the extent similar to the case where the discharge duration is between the first threshold and the second threshold. Therefore, combustion variation of the engine1is reduced. Next, the case where the first discharge duration detected by the ignition device7is above (longer than) the second threshold is described. In this case, the center of the swirl vortex is deviated to the exhaust-valve side inside the cylinder11. As illustrated in chart1103ofFIG.11, the supplemental ignition control module84causes the spark plug25to perform the second supplemental ignition1109. The spark plug25carries out the second supplemental ignition1109at the second operation timing in the latter half of the compression stroke. The timing of the second supplemental ignition1109is later than the timing of the first supplemental ignition1108. P1503and P1504inFIG.15are views illustrating the flow change and distribution of the hot plasma inside the cylinder11when the center of the swirl vortex is deviated to the exhaust-valve side. When the center of the swirl vortex is deviated to the exhaust-valve side, as illustrated in P1503, the velocity distribution inside the cylinder11in the latter half the compression stroke includes an area near the liner where the flow velocity is extremely high. The hot plasma generated by the spark plug25at the central part inside the cylinder11at the late timing in the latter half of the compression stroke, is carried radially outwardly, and rides on the fast flow in the circumferential direction to be promptly carried to the intake-valve side in the circumferential direction along the liner. As a result, the temperature of the mixture gas on the intake-valve side is increased at the ignition timing (P1504). After the second supplemental ignition1109, the main ignition control module82causes the spark plug25to ignite the mixture gas at the given timing near the compression TDC in the latter half of the compression stroke (see the main ignition1107of chart1103). As described above, the flame is difficult to be propagated toward the intake-valve side since the propagating direction is curved by the swirl vortex with the deviated center. However, since the temperature of the mixture gas is high on the intake-valve side, the flame propagation toward the intake-valve side is accelerated. Accordingly, the combustion speed is increased to the extent similar to the case where the discharge duration is between the first threshold and the second threshold. Therefore, combustion variation of the engine1is reduced. Therefore, by performing the supplemental ignition according to the flowing state inside the cylinder11, even when the center of the swirl vortex varies due to the variation in the state of the intake flow between the cycles, the ECU10can make the combustion speed to be constant or substantially constant. Thus, combustion variation of the engine1can be reduced. Note that the energies applied to the spark plug25in the first electric discharge, the second electric discharge, the first supplemental ignition, the second supplemental ignition, and the main ignition may be the same as, or different from each other. Moreover, in the first supplemental ignition and the second supplemental ignition, the spark plug25may generate a cold plasma by being repetitively applied with short voltage pulses. The cold plasma also accelerates the flame propagation, and thus contributes to the improvement in the combustion speed. (Controlling Process of Engine Control Device) Next, a controlling process of the control device of the engine1described above is described with reference to the flowchart ofFIG.16. First, at step S1, the ECU10acquires the sensor values of the sensors SW1to SW9. Next, at step S2, the ECU10calculates the demanded torque of the engine1based on the acquired sensor values. At step S3, the ECU10determines the injection amount and injection timing of the main injection, which can achieve the demanded torque. The ECU10also determines the main ignition timing. At step S4, the ECU10determines the timings of the first electric discharge and the second electric discharge. At this step, the ECU10also determines the time constant Δt for the execution of the first electric discharge. For example, the ECU10may adjust the time constant Δt according to the operating state of the engine1(i.e., the load and/or the speed of the engine1) Next, at step S5, the ECU10causes the injector6to carry out the main injection1104based on the injection amount and injection timing determined at Step S3. As illustrated inFIG.11, the injector6performs the main injection1104during the intake stroke. At step S6, the ECU10causes the ignition device7to carry out the first electric discharge1105. The ignition device7performs the first electric discharge1105during the intake stroke, and detects the first discharge duration. Moreover, at step S7, the ECU10causes the ignition device7to carry out the second electric discharge1106. The ignition device7performs the second electric discharge1106in the early half of the compression stroke, and detects the second discharge duration. At step S8, the ECU10determines whether the first discharge duration is below the first threshold, and whether the second discharge duration is below the first threshold. When the ECU10determines as YES at step S8(when the first discharge duration or the second discharge duration is below the first threshold), the process proceeds to Step s10. When the ECU10determines as NO at step S8, the process proceeds to step S9. At step S9, the ECU10determines whether the first discharge duration is above the second threshold, and whether the second discharge duration is above the second threshold. When the ECU10determines as YES at step S9(when the first discharge duration or the second discharge duration is above the second threshold), the process proceeds to step S11. When the ECU10determines as NO at step S9, the supplemental fuel is not injected. At step S10, the ECU10determines the duration and the timing of the first supplemental ignition1108. As described above, the timing of the first supplemental ignition1108is advanced from the timing of the second supplemental ignition1109. At step S11, the ECU10determines the duration and the timing of the second supplemental ignition1109. As described above, the timing of the second supplemental ignition1109is retarded from the timing of the first supplemental ignition1108. The duration and the timing of the first supplemental ignition1108, and the duration and the timing of the second supplemental ignition1109may be determined, for example, according to the operating state of the engine1. After the ECU10determines the duration and the timing of the supplemental ignition, at step S12, the ECU10executes the supplemental ignition in the early or latter half of the compression stroke (in the case of the first supplemental ignition1108), or in the latter half of the compression stroke (in the case of the second supplemental ignition1109). Then, at step S13, the ECU causes the spark plug25to perform the main ignition to the mixture gas, which starts the combustion of the mixture gas. Note that the injector6is not limited to injecting the main fuel during the intake stroke, but may inject the main fuel during the compression stroke. The spark plug25may perform the first electric discharge before or after the injection of the main fuel. Similarly, the spark plug25may perform the second electric discharge before or after the injection of the main fuel. Moreover, the technology disclosed herein is applicable not only to the engine1with the configuration described above, but to engines with various configurations. It should be understood that the embodiments herein are illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof, are therefore intended to be embraced by the claims. DESCRIPTION OF REFERENCE CHARACTERS 1Engine10ECU (Controller)11Cylinder1311Sloped Surface (Ceiling)1312Sloped Surface (Ceiling)25Spark Plug6Injector (Fuel Injector)7Ignition Device81Main Fuel Injection Module82Main Ignition Control Module83Determination Module84Supplemental Ignition Control Module | 57,745 |
11859575 | DETAILED DESCRIPTION FIG.1shows an internal combustion engine1comprising the arrangement according to aspects of the invention. The depiction shows two combined cross-sections in order to explain the principle of the arrangement. It should be mentioned that the cooling medium passages of the first set of cooling medium passages13and the cooling medium passages of the second set of cooling medium passages14actually have an angular separation, which is not shown inFIG.1, but can be seen inFIG.5. Proper cross sections through a cooling medium passage of the first set of cooling medium passages13and a cooling medium passage of the second set of cooling medium passages14are shown inFIGS.2and3, respectively. The internal combustion engine1comprises the arrangement including the crank case2, the cylinder liner3, and the cylinder head5. The cylinder liner3is mounted in a simple and easy manufacturable and maintainable manner in a cylinder of the crank case2via a flange4, which is arranged circumferentially around a body11of the cylinder liner3(top hung cylinder liner3). For this purpose, the flange4is braced between the cylinder head5and the crank case4. This bracing can for example be achieved through load screws around the periphery of the cylinder (not depicted). The flange4in this embodiment has a substantially rectangular cross-section with a chamfer on the outer edge facing the cylinder head. Between the flange4and the facing surface of the cylinder head5, there is a head gasket20sealing the combustion zone6. The cylinder of the crank case2as well as the body11of the cylinder liner3with its outer surface18and its inner surface19and the circumferential surface8of the flange of the cylinder liner3are substantially of a cylindrical shape. The flange4, and consequently the circumferential surface8of the flange4, completely reach around the body11of the cylinder liner3. According to aspects of the invention, there is a flange cooling cavity7arranged on the circumferential surface8of the flange4. The flange cooling cavity7is further delimited by the cylinder head5. For this purpose, the cylinder head5has a peripheral surface extending the circumferential surface8of the flange4in the depiction above the head gasket20. The direction “above” the flange4is aligned with a longitudinal axis X (seeFIG.5) of the cylinder liner3. The flange cooling cavity7covers slightly more than half of the height of the circumferential surface8of the flange4and a roughly equal amount of a peripheral surface of the cylinder head5(as well as the head gasket20). There is a liner cooling cavity9delimited by the outer surface18of the cylinder liner3on the inside and the crank case2on the outside. Therefore, the cylinder liner3is in direct contact with the cooling medium during operation of the internal combustion engine1(wet cylinder liner3). As mentioned in the introduction, the advantage of the wet cylinder liner3is a higher heat transfer as compared to dry cylinder liners where the cooling cavity is arranged inside the crank case2. The liner cooling cavity9is further delimited by a wall17of the flange4, the wall facing away from the cylinder head5. Just like the flange cooling cavity7, the liner cooling cavity9extends all the way around the cylinder liner3. There is also a head cooling cavity12, which is disposed inside the cylinder head5for cooling the same, in particular for cooling the fire plate (in the depiction ofFIG.1below the head cooling cavity12) as well as intake and exhaust ports/valves. The flange cooling cavity7, according to aspects of the invention, is tied into the cooling circuit througha first set of cooling medium passages13providing fluid communication between the liner cooling cavity9and the flange cooling cavity7, anda second set of cooling medium passages14providing fluid communication between the flange cooling cavity7and the head cooling cavity12. The first set of cooling medium passages13and the second set of cooling medium passages14can easily be manufactured using bores in the crank case2and the cylinder head5. In particular, the first set of cooling medium passages13can be manufactured using two bores, each of which meets at a certain point inside the crank case2. Of course, one of these bores originates at a location where the liner cooling cavity9is located and a second one of these bores originates where the flange cooling cavity7is located. First openings15interface the first set of cooling medium passages13and the flange cooling cavity7. Second openings16interface the flange cooling cavity7and the second set of cooling medium passages14. It should be mentioned that the outer border of the flange cooling cavity7can also be formed by a further component part separate from the crank case2, if this is desired. Such a separate component part can then of course include (at least part of) the first set of cooling medium passages13. In this embodiment, a pump (not shown) is provided for creating a cooling medium flow from the liner cooling cavity9through the flange cooling cavity7to the head cooling cavity12. The cooling medium flow can however also be directed from the head cooling cavity12through the flange cooling cavity7to the liner cooling cavity9. As mentioned before, the first openings15and the second openings16, and consequently at least partly the first set of cooling medium passages13and the second set of cooling medium passages14, can have an angular separation (seeFIG.5). Accordingly, the first openings15and the second openings16would then not be visible in a single cross-section as depicted inFIG.1. In this sense,FIG.1is only for describing the basic principle of aspects of the invention in this regard. “True” cross-sectional views are depicted inFIGS.2to4, namelyFIG.2a cross-sectional view through a cooling passage of the first set of cooling medium passages13,FIG.3a cross-sectional view through a cooling passage of the second set of cooling medium passages14, andFIG.4a cross-sectional view, where none of the first set of cooling medium passages13or the second set of cooling medium passages14are visible. FIG.5shows a cross-sectional “top view”, i.e., along the longitudinal axis X from the side of the cylinder head5and through the cylinder head5. The longitudinal axis X is perpendicular to the view ofFIG.5located at the indicated location. The longitudinal axis X pertains to the cylinder liner3. In this embodiment, the longitudinal axis X substantially coincides with the centre axis of the cylinder of the crank case2. The locations of the first set of cooling medium passages13are indicated by eight bars. The locations of the second set of cooling medium passages14are indicated by eight arrows. The locations of the first openings15and the second openings16are apparent from these indications. Not all of the cooling passages are furnished with reference numerals. The first set of cooling medium passages13and the second set of cooling medium passages14are generally embodied as depicted inFIG.2andFIG.3, respectively. Clearly, there is an angular separation, i.e., a non-zero angle with the position of the longitudinal axis X as centre point, between each of the first openings15on the one hand and each of the second openings16on the other hand. This angular separation causes the cooling medium flow through the flange cooling cavity7to at least partly have a circumferential direction around the flange4, which serves to improve the heat transfer in this area. FIG.5also clearly shows that some of the second set of cooling medium passages14are aligned radially with respect to the longitudinal axis X and some are not, in order to optimize the cooling of the cylinder head5in the vicinity of intake and exhaust ports (valve seats). In this embodiment of the invention, the cooling medium passages of the first set of cooling medium passages13are aligned radially with respect to the longitudinal axis X. In other conceivable embodiments of the invention, this does not have to be the case. The intake and exhaust ports are the four circular structures roughly in the centre ofFIG.5, the larger ones being the exhaust ports. FIG.5shows that there are more of the second set of cooling medium passages14near the exhaust ports/valves in order to improve the cooling in this area, as the exhaust ports/valves experience higher thermal loads than the intake ports/valves stemming from the exhaust gas after combustion. The Figures depict a single cylinder of the internal combustion engine1. Of course, most internal combustion engines1can, and in most cases will, have more than one cylinder. The invention can be realised on all of the cylinders of the internal combustion engine1according to aspects of the invention or a subset thereof. | 8,813 |
11859576 | DETAILED DESCRIPTION Referring toFIG.1, there is shown a power module10for an internal combustion engine. Power module10may include a cylinder liner12and a connecting rod14and cap16, coupled with a piston (not shown) positioned within cylinder liner12. Power module10may also include a cylinder head assembly20having a cylinder head21including a cylinder head casting26. A water jacket18may be attached to cylinder head21and extends around cylinder liner12to provide a flow of a liquid engine coolant such as a mixture of water and conventional engine coolant around cylinder liner12and into cylinder head21. A combustion chamber not visible inFIG.1is formed by cylinder head21, cylinder liner12, and the piston therein. In a practical implementation strategy power module10may be one of several power modules supported in a cylinder block, for instance, in a V-configuration. Other configurations such as an inline configuration are within the scope of the present disclosure. Power module10may be used in an internal combustion engine in a wide variety of applications, including vehicle propulsion, electric power generation, operation of a pump, compressor, or various others. In one embodiment, power module10is one of several power modules in an internal combustion engine system in a locomotive. Cylinder head21and cylinder head casting26, referred to at times interchangeably herein, may be formed of a single piece of casted metallic material such as an iron or a steel, or potentially an aluminum material. A plurality of engine valves22each associated with a valve return spring24are supported in cylinder head casting26and operable to control fluid communication between a combustion chamber in power module10and an intake system and exhaust system in a generally conventional manner. Power module10and the associated engine may be operated in a conventional fourcycle pattern, although the present disclosure is not thereby limited. Engine coolant conveyed through cylinder head casting26can exchange heat with material of cylinder head casting26and associated components, including a fuel injector and a fuel injector sleeve to be described. As explained above, cylinder heads in certain applications can experience various thermal and mechanical fatigue phenomena. As will be further apparent from the following description, cylinder head assembly20is structured for improved performance with regard to heat rejection and extended cylinder head fatigue life. Referring also now toFIG.2, there are shown features of cylinder head assembly20in further detail. Valve stem inserts28may be resident in cylinder head21and structured to support and guide engine valves in a generally conventional manner. Valve seat inserts30may also be installed in cylinder head21also in a generally conventional manner. It is contemplated that cylinder head assembly20when coupled with other components of power module10may include two exhaust valves and two intake valves, although the present disclosure is not thereby limited. Cylinder head casting26also includes a top deck surface32to which a valve cover (not shown) may be attached, a fire deck34having a lower fire deck surface36exposed to combustion gases, and a middle deck37including an upward facing middle deck surface38. Cylinder head casting26further has formed therein a coolant cavity40to convey a flow of engine coolant supplied by way of water jacket18, and an injector bore42fluidly connected to coolant cavity40. In cylinder head casting26coolant cavity40extends around an exhaust conduit44and an intake conduit46each extending through fire deck34. Exhaust conduit44may be one of two exhaust conduits, fluidly connecting to an exhaust manifold (not shown), and intake conduit46may be one of two intake conduits fluidly connecting to an intake manifold (not shown). Injector bore42may include a cylindrical upper bore section48formed by an injector well50extending downwardly from top deck surface32to coolant cavity40. Injector bore42may also include a sleeve tip hole52, cylindrical in shape, extending through fire deck34, and a cylindrical middle bore section54formed by a cylindrical surface55extending upwardly from sleeve tip hole52and terminating at upward facing middle deck surface38. Upper bore section48, middle bore section54, and sleeve tip hole52may be arranged coaxially about a bore center axis66. Referring also now toFIG.3, cylinder head assembly20may further include an injector sleeve60within injector bore42, and including an outer sleeve surface62, and an inner sleeve surface64extending circumferentially around a longitudinal axis66, commonly labeled with bore center axis66, and axially from a first sleeve end68to a cylindrical second sleeve end70within sleeve tip hole52and extending through fire deck34. Cylindrical second sleeve end70may include a sleeve tip (not numbered), generally arranged close to, and typically parallel to, lower fire deck surface36, and exposed to combustion gases. Cylindrical second sleeve end70may be interference-fitted with cylinder head casting26within sleeve tip hole52and thereby forms a coolant and combustion seal. Referring also now toFIG.4, fuel injector sleeve60is further understood to include an elongate sleeve body also labeled with reference numeral60, and including outer sleeve surface62and inner sleeve surface64. Inner sleeve surface64forms an injector socket 72 sized and shaped to accept a fuel injector and extending axially from first sleeve end68to cylindrical second sleeve end70that forms injector tip hole74. Inner sleeve surface64may further include an injector clamping surface76adjacent to cylindrical second sleeve end70. Injector clamping surface76may include a conical injector clamping surface76in some embodiments. Elongate sleeve body60may further include a radially outward shoulder78having a sleeve clamping surface80formed thereon and facing a direction of cylindrical second sleeve end70. Outer sleeve surface62forms a wetted wall of coolant cavity40at a location axially between radially outward shoulder78and first sleeve end68. Elongate sleeve body60may further include a straight cylindrical wall82extending from radially outward shoulder78in a direction of cylindrical second sleeve end70. Referring also now toFIG.6, a second straight cylindrical wall83may extend upwardly from radially outward shoulder78. Elongate sleeve body60further includes a reaction wall84having conical injector clamping surface76formed thereon and extending transversely from cylindrical second sleeve end70to straight cylindrical wall82. Reaction wall84is also understood to extend axially between injector clamping surface76and sleeve clamping surface80. When installed in cylinder head casting26sleeve clamping surface80is in contact with upward facing middle deck surface38, and reaction wall84transfers an injector clamping load to upward facing middle deck surface38, as further described herein. With focus onFIGS.4and6, it can be noted reaction wall84may include an increased wall thickness relative to wall thicknesses of cylindrical second sleeve end70and straight cylindrical wall82. It can also be noted from the drawings that outer sleeve surface62includes, upon reaction wall84, a convex profile opposite to injector clamping surface76, and a linear profile transitioning between the convex profile and straight cylindrical wall82. It can also be noted that a convexity formed by reaction wall84is biased or bulged downwardly in the illustrated embodiment. A relief groove86may be formed in radially outward shoulder78and extends circumferentially around axis66at a location that is radially between sleeve clamping surface80and outer sleeve surface62. Relief groove86is thus understood to be radially inward of sleeve clamping surface80. Radially outward shoulder78may have a recurving hook shape in some embodiments, and protrudes radially outward of outer sleeve surface62relative to portions thereof located axially between shoulder78and first sleeve end68and axially between shoulder78and cylindrical second sleeve end70. Cylindrical upper bore section48, cylindrical middle bore section54, and sleeve tip hole52may be successively stepped-in in diameter, in a direction of lower fire deck surface36. It can further be noted from the drawings that upward facing middle deck surface38may be planar and intersected by a cylinder defined by cylindrical upper bore section48. Upward facing middle deck surface38may also be located closer to lower fire deck surface36than to top deck surface32. Fire deck34may also include a planar upward facing fire deck surface88extending circumferentially around sleeve tip hole52. Reaction wall84may include a downward facing end surface90, and a coolant clearance92extends axially between downward facing end surface90and upward facing fire deck surface88. Coolant clearance92may also extend radially inward to cylindrical second sleeve end70, thus enabling a flow of coolant conveyed through cylinder head casting26to exchange heat directly with reaction wall84and with cylindrical second sleeve end70. As can be seen inFIG.6, reaction wall84may be within a lower axial half102of injector sleeve60, with an upper axial half100of injector sleeve60including first sleeve end68. Referring now also toFIG.5, upward facing middle deck surface38may extend circumferentially and discontinuously around axis66. A plurality of coolant feed openings94may each be formed in part by discontinuities95, or gaps, in upward facing middle deck surface38and fluidly connect cylindrical middle bore section54to coolant cavity40. In an implementation, the plurality of coolant feed openings94include open-channel coolant feed openings94. Cylinder head casting26may further include at least one closed-channel coolant feed opening96fluidly connected to cylindrical middle bore section54at a location axially between upward facing middle deck surface38and sleeve tip hole52. As can be envisioned fromFIG.5when fuel injector sleeve60is installed in contact with upward facing middle deck surface38discontinuities95may provide paths for engine coolant flow up and around fuel injector sleeve60. Liquid engine coolant may be pumped or passively conveyed through the one or more closed-channel coolant feed openings96to flow around fuel injector sleeve60to exchange heat therewith, and then conveyed upwardly into upper regions of coolant cavity40, for eventually flowing out of cylinder head casting26and to a radiator or other heat exchanger, eventually to be recirculated. INDUSTRIAL APPLICABILITY Referring to the drawings generally, but also now focusing onFIG.7, there are shown portions of cylinder head assembly20where a fuel injector56is installed in fuel injector sleeve60and clamped in place by way of a so-called “crab” clamp58engaged with fuel injector56and attached to top deck surface32, thereby applying a downward clamping load on fuel injector56. As explained above, in certain prior strategies fuel injectors and/or fuel injector sleeves were often clamped in a cylinder head such that a clamping load on the fuel injector was reacted by way of the cylinder head fire deck. InFIG.7, an example load path98is shown extending downwardly through fuel injector58, and applied to injector clamping surface76. A second example load path99is shown whereby it can be seen that the clamping load is reacted by reaction wall84axially and transversely upward to radially outward shoulder78. It can further be appreciated that the injector clamping load is transferred through radially outward shoulder78downwardly to upward facing middle deck surface38. Upward facing middle deck surface38may be part of or physically connected to middle deck37of cylinder head casting26, and thereby enabling the injector clamping load to be redirected entirely out of fire deck34. During operation of an internal combustion engine employing power module20, fuel injector58may be actuated, such as by way of rotation of a cam, to pressurize fuel, for example a liquid diesel distillate fuel, to a relatively high injection pressure. Fuel injector actuation, combustion of the injected fuel and air in the associated combustion chamber, and pressurization action of the associated piston pressurizing gases in the combustion chamber to an auto-ignition pressure, results in significant loading on both the fuel injector and the cylinder head itself. The rapidly changing pressures and other loads could in earlier strategies result in the fire deck deforming up and down almost akin to the membrane of a drum. According to the present disclosure the contribution to such loading that would have previously been made by the injector clamping load is reduced or eliminated entirely, enabling material of the middle deck region to react the injector clamping load, and limit the extent to which fire deck34is caused to deform. As a result, improved fatigue life is expected to be observed. The present description is for illustrative purposes only, and should not be construed to narrow the breadth of the present disclosure in any way. Thus, those skilled in the art will appreciate that various modifications might be made to the presently disclosed embodiments without departing from the full and fair scope and spirit of the present disclosure. Other aspects, features and advantages will be apparent upon an examination of the attached drawings and appended claims. As used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Where only one item is intended, the term “one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. | 13,879 |
11859577 | DESCRIPTION OF EMBODIMENT In the following, an embodiment of the present invention will be described with reference to the drawings. First, referring toFIG.1toFIG.8, an overall structure of an engine (engine device) constituted by a diesel engine will be described. In the descriptions below, opposite side portions parallel to a crankshaft5(side portions on opposite sides relative to the crankshaft5) will be defined as left and right, a side where a flywheel housing7is disposed will be defined as front, and a side where a cooling fan9is disposed will be defined as rear. For convenience, these are used as a benchmark for a positional relationship of left, right, front, rear, up, and down in an engine1. As shown inFIG.1toFIG.8, an intake manifold3and an exhaust manifold4are disposed in one side portion and the other side portion of the engine1parallel to the crankshaft5. In the embodiment, the intake manifold3provided on a right surface of a cylinder head2is formed integrally with the cylinder head2. The exhaust manifold4is provided on a left surface of the cylinder head2. The cylinder head2is mounted on a cylinder block6in which the crankshaft5and a piston (not shown) are disposed. The cylinder block6pivotally supports the crankshaft5such that the crankshaft5is rotatable. The crankshaft5has its front and rear distal ends protruding from front and rear surfaces of the cylinder block6. The flywheel housing7is fixed to one side portion of the engine1(in the embodiment, a front surface side of the cylinder block6) intersecting the crankshaft5. A flywheel8is disposed in the flywheel housing7. The flywheel8, which is pivotally supported on the front end side of the crankshaft5, is configured to rotate integrally with the crankshaft5. The flywheel8is configured such that power of the engine1is extracted to an actuating part of a work machine (for example, a hydraulic shovel, a forklift, or the like) through the flywheel8. The cooling fan9is disposed in the other side portion of the engine1(in the embodiment, a rear surface side of the cylinder block6) intersecting the crankshaft5. A rotational force is transmitted from the rear end side of the crankshaft5to the cooling fan9through a V-belt10. An oil pan11is disposed on a lower surface of the cylinder block6. A lubricant is stored in the oil pan11. The lubricant in the oil pan11is suctioned by an oil pump12(seeFIG.11) disposed on the right surface side of the cylinder block6, the oil pump12being arranged in a coupling portion where the cylinder block6is coupled to the flywheel housing7. The lubricant is then supplied to lubrication parts of the engine1through an oil cooler13and an oil filter14that are disposed on the right surface of the cylinder block6. The lubricant supplied to the lubrication parts is then returned to the oil pan11. The oil pump12is configured to be driven by rotation of the crankshaft5. In the coupling portion where the cylinder block6is coupled to the flywheel housing7, a fuel feed pump15for feeding a fuel is attached. The fuel feed pump15is disposed below an EGR device24. A common rail16is fixed to a side surface of the cylinder block6at a location below the intake manifold3of the cylinder head2. The common rail16is disposed above the fuel feed pump15. Injectors17(seeFIG.24) for four cylinders are provided on an upper surface of the cylinder head2which is covered with a head cover18. Each of the injectors17has a fuel injection valve of electromagnetic-controlled type. Each of the injectors17is connected to a fuel tank118(seeFIG.24) through the fuel feed pump15and the common rail16having a cylindrical shape. The fuel tank118is mounted in a work vehicle. A fuel in the fuel tank118is pressure-fed from the fuel feed pump15to the common rail16, so that a high-pressure fuel is stored in the common rail16. By controlling the opening/closing of the fuel injection valves119(seeFIG.24) of the injectors17, the high-pressure fuel in the common rail16is injected from the injectors17to the respective cylinders of the engine1. A blow-by gas recirculation device19is provided on an upper surface of the head cover18covering intake and exhaust valves (not shown), etc. disposed on the upper surface of the cylinder head2. The blow-by gas recirculation device19takes in a blow-by gas that has leaked out of a combustion chamber of the engine1or the like toward the upper surface of the cylinder head2. A blow-by gas outlet of the blow-by gas recirculation device19is in communication with an intake part of a two-stage turbocharger30through a recirculation hose68. A blow-by gas, from which a lubricant component is removed in the blow-by gas recirculation device19, is then recirculated to the intake manifold3via the two-stage turbocharger30. An engine starting starter20is attached to the flywheel housing7. The starter20is disposed below the exhaust manifold4. A position where the starter20is attached to the flywheel housing7is below a coupling portion where the cylinder block6is coupled to the flywheel housing7. A coolant pump21for circulating a coolant is provided in a portion of the rear surface of the cylinder block6, the portion being a little left-hand. The coolant pump21is disposed below the cooling fan9. Rotation of the crankshaft5causes the coolant pump21as well as the cooling fan9to be driven through the cooling fan driving V-belt10. Driving the coolant pump21causes a coolant in a radiator (not shown) mounted in the work vehicle to be supplied to the coolant pump21. The coolant is then supplied to the cylinder head2and the cylinder block6, to cool the engine1. A coolant inlet pipe22disposed below the exhaust manifold4is provided on the left surface of the cylinder block6and is fixed at a height equal to the height of the coolant pump21. The coolant inlet pipe22is in communication with a coolant outlet of the radiator. A coolant outlet pipe23that is in communication with a coolant inlet of the radiator is fixed to a rear portion of the cylinder head2. The cylinder head2has a coolant drainage35that protrudes rearward from the intake manifold3. The coolant outlet pipe23is provided on an upper surface of the coolant drainage35. The inlet side of the intake manifold3is coupled to an air cleaner (not shown) via a collector25of an EGR device24(exhaust-gas recirculation device) which will be described later. Fresh air (outside air) suctioned by the air cleaner is subjected to dust removal and purification in the air cleaner, then fed to the intake manifold3through the collector25, and then supplied to the respective cylinders of the engine1. In the embodiment, the collector25of the EGR device24is coupled to the right side of the intake manifold3which is formed integrally with the cylinder head2to form the right surface of the cylinder head2. That is, an outlet opening of the collector25of the EGR device24is coupled to an inlet opening of the intake manifold3provided on the right surface of the cylinder head2. In this embodiment, the collector25of the EGR device24is coupled to the air cleaner via an intercooler (not shown) and the two-stage turbocharger30, as will be described later. The EGR device24includes: the collector25serving as a relay pipe passage that mixes a recirculation exhaust gas of the engine1(an EGR gas from the exhaust manifold4) with fresh air (outside air from the air cleaner), and supplies a mixed gas to the intake manifold3; an intake throttle member26that communicates the collector25with the air cleaner; a recirculation exhaust gas tube28that constitutes a part of a recirculation flow pipe passage connected to the exhaust manifold4via an EGR cooler27; and an EGR valve member29that communicates the collector25with the recirculation exhaust gas tube28. The EGR device24is disposed on the right lateral side of the intake manifold3in the cylinder head2. The EGR device24is fixed to the right surface of the cylinder head2, and is in communication with the intake manifold3in the cylinder head2. In the EGR device24, the collector25is coupled to the intake manifold3on the right surface of the cylinder head2, and an EGR gas inlet of the recirculation exhaust gas tube28is coupled and fixed to a front portion of the intake manifold3on the right surface of the cylinder head2. The EGR valve member29and the intake throttle member26are coupled to the front and rear of the collector25, respectively. An EGR gas outlet of the recirculation exhaust gas tube28is coupled to the rear end of the EGR valve member29. The EGR cooler27is fixed to the front surface of the cylinder head2. The coolant and the EGR gas flowing in the cylinder head2flows into and out of the EGR cooler27. In the EGR cooler27, the EGR gas is cooled. EGR cooler coupling bases33,34for coupling the EGR cooler27to the front surface of the cylinder head2protrude from left and right portions of the front surface of the cylinder head2. The EGR cooler27is coupled to the coupling bases33,34. That is, the EGR cooler27is disposed on the front side of the cylinder head2and at a position above the flywheel housing7such that a rear end surface of the EGR cooler27and the front surface of the cylinder head2are spaced from each other. The two-stage turbocharger30is disposed on a lateral side (in the embodiment, the left lateral side) of the exhaust manifold4. The two-stage turbocharger30includes a high-pressure turbocharger51and a low-pressure turbocharger52. The high-pressure turbocharger51includes a high-pressure turbine53in which a turbine wheel (not shown) is provided and a high-pressure compressor54in which a blower wheel (not shown) is provided. The low-pressure turbocharger52includes a low-pressure turbine55in which a turbine wheel (not shown) is provided and a low-pressure compressor56in which a blower wheel (not shown) is provided. An exhaust gas inlet57of the high-pressure turbine53is coupled to the exhaust manifold4. An exhaust gas inlet60of the low-pressure turbine55is coupled to an exhaust gas outlet58of the high-pressure turbine53via a high-pressure exhaust gas tube59. An exhaust gas introduction side end portion of an exhaust gas discharge pipe (not shown) is coupled to an exhaust gas outlet61of the low-pressure turbine55. A fresh air supply side (fresh air outlet side) of the air cleaner (not shown) is connected to a fresh air inlet port (fresh air inlet)63of the low-pressure compressor56via an air supply pipe62. A fresh air inlet port66of the high-pressure compressor54is coupled to a fresh air supply port (fresh air outlet)64of the low-pressure compressor56via a low-pressure fresh air passage pipe65. A fresh air introduction side of the intercooler (not shown) is connected to a fresh air supply port67of the high-pressure compressor54via a high-pressure fresh air passage pipe (not shown). The high-pressure turbocharger51is coupled to the exhaust gas outlet58of the exhaust manifold4, and is fixed to the left lateral side of the exhaust manifold4. On the other hand, the low-pressure turbocharger52is coupled to the high-pressure turbocharger51via the high-pressure exhaust gas tube59and the low-pressure fresh air passage pipe65, and is fixed above the exhaust manifold4. Thus, the exhaust manifold4and the high-pressure turbocharger51with a small diameter are disposed side-by-side with respect to the left-right direction below the low-pressure turbocharger52with a large diameter. As a result, the two-stage turbocharger30is arranged so as to surround the left surface and the upper surface of the exhaust manifold4. That is, the exhaust manifold4and the two-stage turbocharger30are arranged so as to form a rectangular shape in a rear view (or front view), and are compactly fixed to the left surface of the cylinder head2. Next, referring toFIG.9toFIG.13, a configuration of the cylinder block6will be described. The cylinder block6is provided with a left housing bracket portion304and a right housing bracket portion305(protruding portions) that are disposed in end portions of a left surface301and a right surface302of the cylinder block6, the end portions being on the front surface303side and extending in a direction along a crankshaft center300. The flywheel housing7is fixed to the left housing bracket portion304and the right housing bracket portion305with a plurality of bolts. A left-side first reinforcing rib306, a left-side second reinforcing rib307, a left-side third reinforcing rib308, and a left-side fourth reinforcing rib309, which are arranged in this order from up to down (from the top deck side to the oil pan rail side), are provided between the left housing bracket portion304and a side wall of the left surface301. A right-side first reinforcing rib310and a right-side second reinforcing rib311, which are arranged in this order from up to down, are disposed between the right housing bracket portion305and the side wall of the right surface302. The housing bracket portions304,305and the reinforcing ribs306to311are formed integrally with the cylinder block6. Each of the reinforcing ribs306to311extends in the direction along the crankshaft center300. In a plan view, each of the housing bracket portions304,305has a substantially wide triangular shape. The left-side reinforcing ribs307,308,309and the right-side second reinforcing rib311have linear portions307a,308a,309a,311athat extend from the substantially triangular portions toward a rear surface312of the cylinder block6(seeFIG.7andFIG.8, too). The reinforcing ribs306,307,308are disposed in a cylinder portion of the cylinder block6. The reinforcing ribs309,310,311are disposed in a skirt portion of the cylinder block6. Each of the left surface301and the right surface302is provided with two mount attachment pedestals317for attachment of an engine mount which couples the engine1to a vehicle body. The two mount attachment pedestals317are arranged one behind the other with respect to the front-rear direction, and protrude at positions close to the oil pan rail. The left-side fourth reinforcing rib309is coupled to the two mount attachment pedestals317protruding from the left surface301. The right-side second reinforcing rib311is coupled to the two mount attachment pedestals317protruding from the right surface302. As shown inFIG.17, a crank case covering member326is secured to the rear surface312of the cylinder block6with bolts. The crank case covering member326covers surroundings of the crankshaft5so as not to expose the inside of a crank case to the outside of the engine1. The oil pan11is fastened to a lower surface of the crank case covering member326with at least one bolt. The housing bracket portions304,305and the reinforcing ribs306to311which are formed integrally with the cylinder block6contribute to enhancement of the rigidity of the cylinder block6, and particularly the rigidity and strength of a portion of the cylinder block6near the front surface303. Thus, vibration and noise of the engine1can be reduced. In addition, since the housing bracket portions304,305and the reinforcing ribs306to311contribute to an increase in a surface area of the cylinder block6, the cooling efficiency of the cylinder block6can be enhanced, and therefore the cooling efficiency of the engine1can be enhanced. A coolant pump attaching part319and an inlet pipe attachment pedestal320are provided so as to protrude from a portion of the left surface301of the cylinder block6, the portion being relatively close to the rear surface312. To the coolant pump attaching part319, a coolant pump21(seeFIG.2, etc.) is attached. To the inlet pipe attachment pedestal320, the coolant inlet pipe22(seeFIG.3, etc.) is attached. The coolant pump attaching part319and the inlet pipe attachment pedestal320are formed integrally with the cylinder block6. A portion of the inlet pipe attachment pedestal320close to the rear surface312is coupled to the coolant pump attaching part319. The coolant pump attaching part319and the inlet pipe attachment pedestal320protrude in a direction away from the crankshaft5, and can enhance the rigidity, the strength, and the cooling efficiency of the cylinder block6. A camshaft casing314(seeFIG.13) for accommodating a camshaft313is provided inside the cylinder block6. Although details are omitted, a crank gear331fixed to the crankshaft5and a cam gear332fixed to the camshaft313are disposed on the front surface303of the cylinder block6. The cam gear332and the camshaft313are rotated in conjunction with the crank gear331. Driving a valve mechanism (not shown) that is associated with the camshaft313causes an intake valve and an exhaust valve (not shown) of the engine1to be opened or closed. The engine1of this embodiment has a so-called overhead valve system. The camshaft casing314is disposed in the cylinder portion of the cylinder block6, and is arranged at a position relatively close to the left surface301. The camshaft313and the camshaft casing314are disposed in the direction along the crankshaft center300. Substantially triangular portions and the linear portions307a,308aof the left-side second reinforcing rib307and the left-side third reinforcing rib308provided on the left surface301of the cylinder block6are arranged close to a position where the camshaft casing314is disposed in a side view, and more specifically at a position overlapping the position where the camshaft casing314is disposed. This embodiment, in which the rigidity of the camshaft casing314and therearound is enhanced by the left-side second reinforcing rib307and the left-side third reinforcing rib308, can prevent distortion of the camshaft casing314. Accordingly, a variation in the rotation resistance and the rotational friction of the camshaft313, which may occur due to distortion of the camshaft casing314, can be prevented, so that the camshaft313can be rotated appropriately to open or close the intake valve and the exhaust valve (not shown) appropriately. Of a lubricant passage provided in the cylinder block6, a part is disposed in the skirt portion of the cylinder block6and arranged at a position relatively close to the right surface302. The part includes a lubricant sucking passage315and a lubricant supply passage316. The lubricant supply passage316is disposed in the skirt portion of the cylinder block6and arranged at a position relatively close to the cylinder portion. The lubricant sucking passage315is arranged at a position relatively close to the oil pan rail as compared to the lubricant supply passage316. One end of the lubricant sucking passage315is opened in an oil pan rail lower surface (a surface opposed to the oil pan11) of the cylinder block6, and is connected to a lubricant sucking pipe (not shown) disposed in the oil pan11. The other end of the lubricant sucking passage315is opened in the front surface303of the cylinder block6, and is connected to a suction port of the oil pump12(seeFIG.11) fixed to the front surface303. One end of the lubricant supply passage316is opened in the front surface303of the cylinder block6at a position different from the position where the lubricant sucking passage315is opened, and is connected to an ejection port of the oil pump12. The other end of the lubricant supply passage316is opened in an oil cooler bracket attachment pedestal318protruding from the right surface302of the cylinder block6, and is connected to a suction port of the oil cooler13(seeFIG.4, etc.) disposed on the oil cooler bracket attachment pedestal318. Not only the lubricant sucking passage315and the lubricant supply passage316but also other lubricant passages are provided in the cylinder block6. On the right surface302of the cylinder block6, the right-side first reinforcing rib310is arranged close to the position where the lubricant supply passage316is arranged in a side view. More specifically, the right-side first reinforcing rib310is arranged so as to overlap the position where the lubricant supply passage316is arranged in a side view. The right-side second reinforcing rib311is arranged close to the position where the lubricant sucking passage315is arranged in a side view. The reinforcing ribs310,311and the passages315,316extend in the direction along the crankshaft center300. In this embodiment, the cooling efficiency in the vicinity of the lubricant sucking passage315, the oil pump12, and the lubricant supply passage316can be enhanced by the right housing bracket portion305, the right-side first reinforcing rib310, and the right-side second reinforcing rib311. In particular, the right-side first reinforcing rib310arranged at a position overlapping the lubricant supply passage316in a side view efficiently dissipates heat in the vicinity of the lubricant supply passage316to the outside. This can lower the temperature of the lubricant flowing into the oil cooler13, and can reduce the amount of heat exchange required of the oil cooler13. A gear train structure of the engine1will now be described with reference toFIG.10toFIG.16. A gear case330is provided in a space surrounded by the front surface303of the cylinder block6, the housing bracket portions304,305, and the flywheel housing7. As shown inFIG.12andFIG.14, front distal end portions of the crankshaft5and the camshaft313protrude from the front surface303of the cylinder block6. The crank gear331is secured to the front distal end portion of the crankshaft5. The cam gear332is secured to the front distal end portion of the camshaft313. A disk-shaped camshaft pulser339is fastened with bolts to a surface of the cam gear332on the flywheel housing7side such that the camshaft pulser339is rotatable integrally with the cam gear332. As shown inFIG.12,FIG.13, andFIG.16, the fuel feed pump15provided in the right housing bracket portion305of the cylinder block6includes a fuel feed pump shaft333as a rotation shaft extending in parallel to the rotation axis of the crankshaft5. The front end side of the fuel feed pump shaft333protrudes from a front surface305aof the right housing bracket portion305. A fuel feed pump gear334is secured to a front distal end portion of the fuel feed pump shaft333. As shown inFIG.13, the right housing bracket portion305of the cylinder block6includes a fuel feed pump attachment pedestal323for arranging the fuel feed pump15above the right-side first reinforcing rib310. The fuel feed pump attachment pedestal323has a fuel feed pump shaft insertion hole324with a size that allows the fuel feed pump gear334to pass therethrough. As shown inFIG.11andFIG.12, the oil pump12, which is disposed on the front surface305aof the right housing bracket portion305and arranged below the fuel feed pump gear334, includes an oil pump shaft335as a rotation shaft extending in parallel to the rotation axis of the crankshaft5. An oil pump gear336is secured to a front distal end portion of the oil pump shaft335. On the front surface303of the cylinder block6, an idle shaft337extending in parallel to the rotation axis of the crankshaft5is provided in a portion surrounded by the crankshaft5, the camshaft313, the fuel feed pump shaft333, and the oil pump shaft335. The idle shaft337is fixed to the front surface303of the cylinder block6. An idle gear338is rotatably supported on the idle shaft337. The idle gear338is meshed with four gears, namely, the crank gear331, the cam gear332, the fuel feed pump gear334, and the oil pump gear336. Rotational power of the crankshaft5is transmitted from the crank gear331to the three gears of the cam gear332, the fuel feed pump gear334, and the oil pump gear336, via the idle gear338. Thus, the camshaft313, the fuel feed pump shaft333, and the oil pump shaft335are rotated in conjunction with the crankshaft5. In the embodiment, the gear ratio among the gears331,332,334,336,338is set such that: two rotations of the crankshaft5correspond to one rotation of the camshaft313; and one rotation of the crankshaft5corresponds to one rotation of the fuel feed pump shaft333and the oil pump shaft335. In this configuration, rotating the cam gear332and the camshaft313in conjunction with the crank gear331which rotates together with the crankshaft5to drive the valve mechanism (not shown) that is associated with the camshaft313causes the intake valve and the exhaust valve (not shown) provided in the cylinder head2to be opened or closed. In addition, rotating the fuel feed pump gear334and the fuel feed pump shaft333in conjunction with the crank gear331to drive the fuel feed pump15causes the fuel in the fuel tank118to be pressure-fed to the common rail16so that a high-pressure fuel is stored in the common rail16. In addition, rotating the oil pump gear336and the oil pump shaft335in conjunction with the crank gear331to drive the oil pump12causes the lubricant in the oil pan11to be supplied to various sliding component parts and the like through a lubricating system circuit (details are not shown) including the lubricant sucking passage315, the lubricant supply passage316, the oil cooler13, the oil filter14, and the like. As shown inFIG.16, the fuel feed pump15serving as an auxiliary machine that is operated in conjunction with rotation of the crankshaft5is secured with bolts to the fuel feed pump attachment pedestal323of the right housing bracket portion305. The right-side first reinforcing rib310is arranged close to the fuel feed pump attachment pedestal323. The right-side first reinforcing rib310is arranged directly under the fuel feed pump15, and the right-side second reinforcing rib311is arranged directly under the right-side first reinforcing rib310. The reinforcing ribs310,311can enhance the rigidity of the fuel feed pump attachment pedestal323, and also can prevent the fuel feed pump15from being contacted by a foreign object such as muddy water or stone coming from below, for protection of the fuel feed pump15. The gear case330that accommodates the gear train will now be described with reference toFIG.10toFIG.12,FIG.14, andFIG.15. A block-side projecting portion321that extends along a peripheral edge of a region including the front surfaces303,304a,305aof the cylinder block6and of the left and right housing bracket portions304,305is provided upright on a peripheral edge portion of the front surfaces303,304a,305a. The block-side projecting portion321is joined with the flywheel housing7. The block-side projecting portion321has a cutout portion321aat a location between the left and right oil pan rails of the cylinder block6. A space between an end surface of the block-side projecting portion321and the front surfaces303,304a,305ain a side view defines a block-side gear casing322. As shown inFIG.14andFIG.15, the flywheel housing7which is made of, for example, cast iron includes a flywheel accommodating part401that accommodates the flywheel8. The flywheel accommodating part401has a bottomed cylindrical shape formed by a circumferential wall surface portion402and a rear wall surface portion403being coupled to each other. The circumferential wall surface portion402has a substantially cylindrical shape and covers the outer circumferential side of the flywheel8. The rear wall surface portion403covers a rear surface side (a surface on the cylinder block6side) of the flywheel8. The flywheel8is accommodated in a space surrounded by the circumferential wall surface portion402and the rear wall surface portion403. The circumferential wall surface portion402is in the shape of a substantially truncated cone with its radius decreasing toward the rear wall surface portion403. The rear wall surface portion403has, in its central portion, a crankshaft insertion hole404through which the crankshaft5is inserted. A housing-side projecting portion405having an annular shape that corresponds to the shape of the block-side projecting portion321of the cylinder block6is coupled to the rear wall surface portion403so as to surround a position where the crankshaft insertion hole404is disposed. The center of the housing-side projecting portion405is deviated upward from the crankshaft insertion hole404. A lower portion of the housing-side projecting portion405, which extends in the left-right direction (lateral direction), is close to the crankshaft insertion hole404and is coupled to the rear wall surface portion403. Upper, left, and right portions of the housing-side projecting portion405are located outside the rear wall surface portion403. A front portion of the circumferential wall surface portion402and a front portion of the housing-side projecting portion405located outside the rear wall surface portion403are coupled to each other in an outer wall portion406. The outer wall portion406has a curved slope shape convexing in a direction away from the crankshaft5. In the flywheel housing7, a lower portion of the flywheel accommodating part401protrudes from the housing-side projecting portion405in a direction away from the crankshaft5. A space between the rear wall surface portion403and an end surface of the housing-side projecting portion405in a side view defines a housing-side gear casing407. This housing-side gear casing407and the above-mentioned block-side gear casing322constitute the gear case330. Inside the flywheel housing7, a lightening space408is formed between an outer wall of the circumferential wall surface portion402of the flywheel accommodating part401and an inner wall of the outer wall portion406. A plurality of ribs409configured to couple the circumferential wall surface portion402to the outer wall portion406are disposed in the lightening space408. The flywheel housing7has a starter attaching part411having a starter attachment pedestal410that is flush with the housing-side projecting portion405. The starter attachment pedestal410is coupled to the circumferential wall surface portion402and the housing-side projecting portion405at a location outside the housing-side projecting portion405. The starter attaching part411has a through hole412bored from the starter attachment pedestal410to the inner wall of the circumferential wall surface portion402. The flywheel housing7is fastened to the front surface303side of the cylinder block6with bolts in thirteen bolt holes351of the block-side projecting portion321of the cylinder block6and in bolt holes353of two housing bolting boss portions352of the front surface303. As shown inFIG.10,FIG.12,FIG.13, andFIG.17toFIG.20, the left housing bracket portion304of the cylinder block6has its peripheral edge portion recessed toward a peripheral edge portion of the flywheel housing7, to form a bracket recessed portion325having a recessed shape. While the flywheel housing7is fixed to the cylinder block6, the starter20is disposed to the starter attachment pedestal410of the flywheel housing7which is exposed on the lower side of the bracket recessed portion325. As shown inFIG.14, an annular ring gear501for the starter20and a crankshaft pulser502are fixed to the outer circumferential side of the flywheel8. The ring gear501and the crankshaft pulser502are fitted in from opposite sides in a thickness direction of the flywheel8. The starter20includes a pinion gear503(seeFIG.12,FIG.19, andFIG.20) that is disposed in the through hole412and is separatably meshed with the ring gear501. Here,FIG.19andFIG.20show a state where the pinion gear503is meshed with the ring gear501. As shown inFIG.20, the through hole412in which an end portion of the starter20with the pinion gear503is inserted is partitioned from an internal space of the gear case330by the housing-side projecting portion405. This can prevent a lubricant, vibration and noise in the gear case330from leaking into the through hole412. In the vicinity of the starter attachment pedestal410, the flywheel housing7made of cast iron is fastened with bolts to the block-side projecting portion321(seeFIG.12andFIG.14) that is provided upright on the peripheral edge portion of the front surface304aof the left housing bracket portion304. In the cylinder block6, the left-side fourth reinforcing rib309that couples the left housing bracket portion304to the left surface301is disposed near the bracket recessed portion325of the left housing bracket portion304which is provided near the starter attachment pedestal410. Thereby, the rigidity of the starter attachment pedestal410and therearound is enhanced. In addition, the bracket recessed portion325of the left housing bracket portion304and a portion of the block-side projecting portion321(seeFIG.12) provided on the front surface303and near the starter attachment pedestal410so as to be continuous with the bracket recessed portion325also enhance the rigidity of the starter attachment pedestal410and therearound. In this embodiment, the starter20can be attached to a portion given a high rigidity by the left-side fourth reinforcing rib309and the like. Thus, mispositioning and deformation of the starter20can be prevented, which may otherwise be caused by distortion of the starter attachment pedestal410or the left housing bracket portion304. Accordingly, breakdown of the starter20and poor meshing between the pinion gear503of the starter20and the ring gear501of the flywheel8can be prevented. As shown inFIG.1,FIG.2,FIG.5, andFIG.17, the starter20is disposed inner than a portion of the flywheel housing7, the portion being located outermost in the engine1on the left surface301side of the cylinder block6with respect to a horizontal direction that is perpendicular to the direction along the crankshaft center300of the crankshaft5and that is parallel to a block upper surface341(cylinder head joining surface) of the cylinder block6. In this manner, the starter20is arranged such that it is not located outermost in the engine1with respect to the horizontal direction. This can make the engine1compact, and can reduce breakdown of the starter20, which may otherwise be caused by contact with a foreign object. As shown inFIG.17andFIG.21, a motor shaft center344of a motor unit343of the starter20is disposed closer to the block lower surface342of the cylinder block6than the crankshaft center300of the crankshaft5is with respect to the horizontal direction. This lowers the center of gravity of the engine1as compared to a configuration in which the starter20is disposed above the crankshaft center300. Accordingly, the center of gravity of a vehicle equipped with the engine1can be lowered. As shown inFIG.5,FIG.6, andFIG.21, the starter20is arranged at a position not overlapping the two-stage turbocharger30with respect to the direction along the crankshaft center300of the crankshaft5, and particularly is arranged at a position not overlapping a lubricant pipe345that circulates the lubricant to the two-stage turbocharger30. As mentioned above, the EGR cooler27is fixed to the front surface of the cylinder head2. With this configuration, even when a liquid such as the lubricant leaks from the two-stage turbocharger30or a liquid such as the coolant leaks from the EGR cooler27, the liquid can be prevented from adhering to the starter20, so that stain and breakdown of the starter20can be prevented, which may otherwise be caused by adherence of the liquid. As shown inFIG.22andFIG.23, an external auxiliary machine328that is operated in conjunction with rotation of the crankshaft5is disposed to an external auxiliary machine attachment pedestal327of the left housing bracket portion304of the cylinder block6. The external auxiliary machine328is, for example, a work machine pump used in a work machine to which the engine1is mounted. The external auxiliary machine328is meshed with the cam gear332(seeFIG.12), and is actuated by rotation of an auxiliary machine gear (not shown) which is in conjunction with rotation of the crankshaft5. The left-side third reinforcing rib308and the left-side fourth reinforcing rib309are disposed near the external auxiliary machine attachment pedestal327. Since reinforcing ribs308,309enhances the rigidity of the external auxiliary machine attachment pedestal327, mispositioning and malfunction of the external auxiliary machine328can be prevented, which may otherwise be caused by distortion of the external auxiliary machine attachment pedestal327. Moreover, the external auxiliary machine328is disposed directly above the starter20, and therefore has a function for protecting the starter20. Accordingly, the starter20can be prevented from being contacted by a foreign object such as a tool coming from above. Thus, breakdown and mispositioning of the starter20can be prevented, which may otherwise be caused by contact with the foreign object. A fuel system structure of a common rail system117and the engine1will now be described with reference toFIG.24. As shown inFIG.24, the fuel tank118is connected to the respective injectors17corresponding to four cylinders provided in the engine1through the fuel feed pump15and the common rail system117. Each injector17has the fuel injection valve119of electromagnetic-controlled type. The common rail system117includes the common rail16having a cylindrical shape. The common rail16is provided on the right surface302of the cylinder block6, and is disposed near the intake manifold3. The fuel tank118is connected to a suction side of the fuel feed pump15with interposition of a fuel filter121and a low-pressure tube122. A fuel in the fuel tank118is suctioned into the fuel feed pump15through the fuel filter121and the low-pressure tube122. Meanwhile, the common rail16is connected to an ejection side of the fuel feed pump15with interposition of a high-pressure tube123. A high-pressure tube connector124is disposed longitudinally midway in the cylindrical common rail16. An end portion of the high-pressure tube123is coupled to the high-pressure tube connector124by screwing with a high-pressure tube connector nut125. The injectors17corresponding to four cylinders are connected to the common rail16with interposition of four fuel injection pipes126, respectively. Fuel injection pipe connectors127corresponding to four cylinders are arranged in a longitudinal direction of the cylindrical common rail16. An end portion of each fuel injection pipe126is coupled to the corresponding fuel injection pipe connector127by screwing with a fuel injection pipe connector nut128. A return pipe connector129(pipe joint member) for returning a surplus fuel, which limits a fuel pressure in the common rail16, is connected to a longitudinal end portion of the common rail16. The return pipe connector129is connected to the fuel tank118through a fuel return pipe130. A surplus fuel in the fuel feed pump15is fed to the return pipe connector129through a pump surplus fuel return pipe131. A surplus fuel in each injector17is fed to the return pipe connector129through an injector surplus fuel return pipe132. That is, the surplus fuel in the fuel feed pump15, a surplus fuel in the common rail16, and the surplus fuel in each injector17are merged in the return pipe connector129, and then collected to the fuel tank118through the fuel return pipe130. Here, it may be possible that the return pipe connector129is connected to the fuel tank118via a pipe joint member (not shown) for returning a filter surplus fuel, the pipe joint member being provided in the fuel filter121. A fuel pressure sensor601that detects a fuel pressure in the common rail16is provided in an end portion of the common rail16opposite to the end portion thereof having the return pipe connector129. Under control by an engine controller600, the degree of opening of a suction metering valve602of the fuel feed pump15is adjusted, while the fuel pressure in the common rail16is monitored based on an output of the fuel pressure sensor601. Thereby, with adjustment of the amount of fuel suctioned by the fuel feed pump15, and thus with adjustment of the amount of fuel ejected by the fuel feed pump15, the fuel in the fuel tank118is pressure-fed to the common rail16by the fuel feed pump15, so that a high-pressure fuel is stored in the common rail16. Under control by the engine controller600, opening/closing of each of the fuel injection valves119is controlled, so that the high-pressure fuel in the common rail16is injected from each injector17to each cylinder of the engine1. That is, by electronically controlling each fuel injection valve119, an injection pressure, an injection timing, and an injection period (injection amount) of the fuel supplied from each injector17can be controlled with a high accuracy. Accordingly, a nitrogen oxide (NOx) discharged from the engine1can be reduced. Noise and vibration of the engine1can be reduced. A pressure reducing valve603of electromagnetic-driven type for adjusting a pressure in the common rail16and a fuel temperature sensor604for detecting a fuel temperature in the fuel feed pump15are also electrically connected to the engine controller600. Other devices as exemplified by various sensors provided in the engine1are also electrically connected to the engine controller600, though not shown. A part of a harness structure which is annexed to the engine1will now be described with reference toFIG.25. A harness connector701that connects component parts of the engine1to the engine controller600(seeFIG.24) and to a battery (not shown) is fixed to the right surface302of the cylinder block6with a connector bracket702interposed therebetween. The harness connector701and the connector bracket702are disposed in a region surrounded by the oil cooler13, the oil filter14, the fuel feed pump15, and the common rail16. A main harness assembly703extending from the harness connector701is guided through a space between the right surface302of the cylinder block6and the connector bracket702to a lower region in the engine1, and then is guided along the linear portion311aof the right-side second reinforcing rib311, through a space between the right surface302and the oil filter14, toward a rear region in the engine1. Furthermore, at a location more rearward in the engine1than the oil filter14, the main harness assembly703is bent upward in the engine1, and is guided through the rear side of the oil cooler13in the engine1, toward the cylinder head2. The main harness assembly703is, in the vicinity of a joining surface where the cylinder head2and the cylinder block6are joined to each other, branched into an intake/exhaust system harness assembly704and a fuel system harness assembly705. The intake/exhaust system harness assembly704is guided along the right surface of the cylinder head2toward the upper side in the engine1, and in the vicinity of an upper portion of the right surface of the head cover18relatively close to the rear side, branched into an intake system harness assembly706and an exhaust system harness assembly707. The intake system harness assembly706is guided along the right surface of the head cover18, toward a front region in the engine1. The exhaust system harness assembly707is guided along the right surface and the rear surface of the head cover18, toward a left region in the engine1. The fuel system harness assembly705is guided through a space between the oil cooler13and the collector25of the EGR device24, toward a front region in the engine1, and is branched into harnesses connected to the fuel pressure sensor601and the pressure reducing valve603of the common rail16and to the suction metering valve602and the fuel temperature sensor604of the fuel feed pump15shown inFIG.24. A layout of the common rail16and therearound will be described with reference toFIG.26toFIG.30. The common rail16having a substantially cylindrical shape is attached to an upper portion of the right surface302of the cylinder block6relatively close to the front side such that a longitudinal direction of the common rail16is along the crankshaft center300(seeFIG.11). The common rail16is disposed on the right surface of the cylinder head2, at a location below the intake manifold3which is formed integrally with the cylinder head2. A front end portion (one end portion) of the common rail16is arranged on the gear case330and on the flywheel housing7. The common rail16includes, in its front end portion, the return pipe connector129(pipe joint member) for returning a surplus fuel, the return pipe connector129limiting a fuel pressure in the common rail16. For example, the return pipe connector129is arranged on the flywheel housing7. A bracket recessed portion621provided in the right housing bracket portion305of the cylinder block6and a housing recessed portion622provided in the flywheel housing7are arranged near an upper front corner of the right surface302of the cylinder block6. As shown inFIG.26, the recessed portions621,622are provided near the upper front corner of the right surface302such that a joining portion where the flywheel housing7and the right housing bracket portion305are joined with each other is at a level lower than the upper surface of the cylinder block6. This allows the front end portion of the common rail16attached to the right surface302of the cylinder block6to extend above the recessed portions621,622toward the upper side of the flywheel housing7. The return pipe connector129includes a connecting portion130ato which one end of the fuel return pipe130(seeFIG.24) is connected, a connecting portion131ato which one end of the pump surplus fuel return pipe131(seeFIG.24) is connected, and a connecting portion132ato which one end of the injector surplus fuel return pipe132(seeFIG.24) is connected. The return pipe connector129is provided therein with an internal fluid passage (not shown) that connects the connecting portions130a,131a,132a, and a fuel pressure regulating valve (not shown) disposed between the internal fluid passage and an internal space of the common rail16. A surplus fuel outlet132bfor a surplus fuel from the injectors17(seeFIG.24) is provided in a portion of the cylinder head2near an intersection between the right surface302and the front surface303of the cylinder block6(seeFIG.12), which in this embodiment means a portion near a corner where the right surface and the front surface of the cylinder head2intersect each other and more specifically means a front end portion of the right surface of the cylinder head2relatively close to the upper side. An injector surplus fuel return pipe132cis disposed in connection between the surplus fuel outlet132band the connecting portion132aof the return pipe connector129. The surplus fuel outlet132bis connected to a surplus fuel outlet of each injector17(seeFIG.24) via a surplus fuel passage (not shown) provided inside a side wall of the cylinder head2and the injector surplus fuel return pipe132(seeFIG.24) disposed within the cylinder head2. Connectors601a,603aof the fuel pressure sensor601and the pressure reducing valve603of the common rail16, which are electrically connected to the engine controller600(seeFIG.24), are disposed below the intake manifold3of the cylinder head2. As shown inFIG.13andFIG.30, the right surface302of the cylinder block6has a concavo-convex surface portion611that corresponds to the shape of a water rail610(coolant passage) which is provided inside the cylinder block6. The connector601aof the fuel pressure sensor601is disposed above a concave region612of the concavo-convex surface portion611. A connecting portion of the connector601ais directed toward the concave region612in a side view. A connecting portion of the connector603aof the pressure reducing valve603is directed toward the right lateral side of the engine1, for example. The four fuel injection pipes126extending from the common rail16toward the cylinder head2pass through a space between the cylinder head2and the EGR device24(exhaust-gas recirculation device), and are connected to the respective injectors17(seeFIG.24). As shown inFIG.29, a midway portion of each of the four fuel injection pipes126is attached to the cylinder head2by a fuel injection pipe fixture614which is attached to the cylinder head2directly or with a spacer member613interposed therebetween. Since the midway portion of each fuel injection pipe126is fixed to the cylinder head2, the fuel injection pipe126causes less vibration, and thus damage of the fuel injection pipe126due to vibration can be prevented. In this embodiment, among the four fuel injection pipes126, two fuel injection pipes126located more frontward in the engine1have their midway portions fixed to the cylinder head2with interposition of a spacer member613having a substantially cylindrical shape. By adjusting the spacer member613to a desired length, the midway portion of the fuel injection pipe126can be fixed at a position that is at any distance from the side surface of the cylinder head2. Thus, the fuel injection pipe126with any shape can be handled without the need to change the design of a surface configuration of the cylinder head2. As shown inFIG.27, the fuel feed pump15attached to the right housing bracket portion305of the cylinder block6is disposed below the EGR device24. As mentioned above, the right-side first reinforcing rib310is arranged directly under the fuel feed pump15, and the right-side second reinforcing rib311is arranged directly under the right-side first reinforcing rib310, to thereby prevent the fuel feed pump15from being contacted by a foreign object such as muddy water or stone coming from below (seeFIG.16). The engine1of this embodiment, in which one end portion of the common rail16attached to the right surface302(one side portion) of the cylinder block6is disposed above the flywheel housing7, can reduce an area of the right surface302of the cylinder block6occupied by a region where the common rail16is disposed, as compared to a configuration in which the whole of the common rail16is disposed on the right surface302of the cylinder block6. Accordingly, the degree of freedom can be enhanced in a layout of other members on the right surface302of the cylinder block6. For example, in the engine device1of this embodiment, the oil cooler13is arranged on the rear side of a rear end portion of the common rail16in the engine1such that the oil cooler13is close to the intake manifold3and the EGR device24. Thereby, a compact arrangement configuration of these component parts can be achieved. In the engine1of this embodiment, the connectors601a,603aof the fuel pressure sensor601and the pressure reducing valve603of the common rail16, which are electrically connected to the engine controller600, are disposed below the intake manifold3which is formed integrally with the cylinder head2. Thus, the intake manifold3can protect the connectors601a,603aagainst contact with a foreign object. In addition, the EGR device24attached to the intake manifold3also protects the connectors601a,603ain the same manner. Since a connection port of the connector601ais directed toward the concave region612of the concavo-convex surface portion611that corresponds to the shape of the water rail610in a side view. This enables a harness-side connector to be attached to the connector601aso as to extend along the concave region612, which can enhance operability in attaching harnesses. Furthermore, this enables the connector601ato be arranged at a location relatively close to the cylinder block6, as compared to a configuration in which the connection port of the connector601ais directed toward the outside of the engine1. Thus, the width of the engine1as a whole can be reduced. In the engine1of this embodiment, the common rail16has, in its front end portion, the return pipe connector129for returning a surplus fuel, and the surplus fuel outlet132bfor a surplus fuel from the respective injectors17is provided near the intersection between the right surface302and the front surface303of the cylinder block6of the cylinder head2in a plan view. Since the return pipe connector129is disposed above the flywheel housing7, the injector surplus fuel return pipe132c(surplus fuel return path) that connects the surplus fuel outlet132bto the connecting portion132aof the return pipe connector129can be shortened and simplified. This can solve a problem of the conventional technique that a surplus fuel return path for a surplus fuel from the injectors17is elongated and complicated. In a case where, for example, the fuel filter121(seeFIG.24) is provided in a work machine or a vehicle equipped with the engine1, a vacant space above the flywheel housing7can be used to shorten and simplify a piping path between the fuel filter121and the connecting portion130aof the return pipe connector129, and also to enhance the degree of freedom in designing the piping path. In the engine1of this embodiment, the EGR device24configured to mix a part of the exhaust gas discharged from the exhaust manifold4with fresh air is coupled to the intake manifold3, and the four fuel injection pipes126extending from the common rail16toward the cylinder head2pass through the space between the cylinder head2and the EGR device24. Thus, the fuel injection pipes126can be protected by the EGR device24. This can solve a problem of the conventional technique having a fuel injection pipe assembled to an outer peripheral portion of an engine device, that is, a problem that deformation of the fuel injection pipe or fuel leakage may be caused due to contact between the engine device and another member during transportation or due to falling of a foreign object, for example. In the engine1of this embodiment, the fuel feed pump15for supplying a fuel to the common rail16is attached to the cylinder block6and is disposed below the EGR device24. This can protect the fuel feed pump15against contact with a foreign object coming from above, such as a tool falling at a time of assembling. Thus, damage of the fuel feed pump15can be prevented. In addition, the fuel feed pump15is attached to the right housing bracket portion305that protrudes from the right surface302of the cylinder block6, and the reinforcing ribs310,311for coupling the right surface302to the right housing bracket portion305are disposed below the fuel feed pump15. This can protect the fuel feed pump15against contact with a foreign object, such as a stone, coming from below. As a result, damage of the fuel feed pump15can be further prevented. In this embodiment, as shown inFIG.27, a space is provided between the oil cooler13and the fuel feed pump15, in order to enable the fuel feed pump15having the fuel feed pump gear334(seeFIG.12) secured thereto to be removed from the right housing bracket portion305without the need to remove the oil cooler13. As shown inFIG.25, the harness connector701and the connector bracket702are arranged between the oil cooler13and the fuel feed pump15. Thereby, with effective utilization of the space between the oil cooler13and the fuel feed pump15, the harness connector701can be arranged at a position surrounded by the oil cooler13, the oil filter14, the fuel feed pump15, and the EGR device24, for protection of the harness connector701. A well-known configuration of the conventional engine includes: an oil cooler for heat exchange between a lubricant and a coolant; and an oil filter for purifying the lubricant by filtration (see, for example, Japanese Patent Application Laid-Open No. 2005-273484). A lubricant path and a coolant path leading to the oil cooler are separately provided. In an engine disclosed in Japanese Patent Application Laid-Open No. 2005-273484, therefore, coolant piping such as pipes and hoses for circulating the coolant through the oil cooler is disposed. According to Japanese Patent Application Laid-Open No. 2005-273484, moreover, a lubricant pipe member for circulating the lubricant between the oil cooler and the oil filter is disposed. For example, a change in oil cooler capacity requires a component part such as piping or a bracket corresponding to the oil cooler capacity. It therefore is necessary to prepare piping for each oil cooler capacity. This involves a problem that an increase number of component parts. The configuration disclosed in Japanese Patent Application Laid-Open No. 2005-273484 requires the lubricant pipe member for connecting the oil cooler to the oil filter, which involves a problem that an increase number of component parts. Thus, the engine1of this embodiment aims to reduce the number of component parts in an engine device including an oil cooler and an oil filter. A structure for attaching the oil cooler13and the oil filter14will be described with reference toFIG.31toFIG.35. The oil cooler13and the oil filter14are disposed on the right surface302of the cylinder block6with an oil cooler bracket631(bracket member) interposed therebetween. In this embodiment, the oil cooler13is a multi-plate type plate stack heat exchanger in which a plurality of plate members are stacked such that an oil passage and a coolant passage are formed alternately in a stacking direction. The oil cooler bracket631is fastened and fixed to an oil cooler bracket attachment pedestal318(attaching part) protruding from the right surface302, with bracket bolts632. The oil cooler bracket631is composed mainly of an oil cooler attaching part633, a coupling portion634, and an oil filter attaching part635. The oil cooler bracket631is a casting. The oil cooler attaching part633, the coupling portion634, and the oil filter attaching part635are integrally formed. The oil cooler attaching part633is substantially in the shape of a flat plate, and has an oil cooler attaching face637on its surface opposite to a joining surface636joined to the oil cooler bracket attachment pedestal318. The oil cooler attaching part633has, in its peripheral edge portion, a plurality of flange portions protruding outward along the joining surface636. Bolt insertion holes638through which the bracket bolts632are inserted are formed in the flange portions. Two bolt placement concavities639are provided in a central portion of the oil cooler attaching face637, the bolt placement concavities639accommodating heads of the bracket bolts632. Each bolt placement concavity639has, at its bottom, a bolt insertion hole638that bores to reach the joining surface636. The coupling portion634is provided upright on the peripheral edge portion of the oil cooler attaching part633, and protrudes in a direction roughly perpendicular to the oil cooler attaching face637, toward the side opposite to the joining surface636. The coupling portion634is disposed in a portion of the oil cooler attaching part633, the portion being located lower when the oil cooler bracket631is attached to the oil cooler bracket attachment pedestal318. The oil filter attaching part635is provided on the distal end side of the coupling portion634. The oil filter attaching part635has an oil filter attaching surface640with an annular shape. The oil filter attaching surface640is provided in a portion of the oil filter attaching part635, the portion being on the side opposite to the oil cooler13which is attached to the oil cooler attaching face637. The oil cooler attaching part633has: a coolant inflow hole641that is connected to a coolant inlet port13aof the oil cooler13; a coolant outflow hole642that is connected to a coolant outlet port13bof the oil cooler13; a lubricant inflow hole643that is connected to a lubricant inlet port13cof the oil cooler13; and a lubricant outflow hole644that is connected to a lubricant outlet port13dof the oil cooler13. The coolant inflow hole641, the coolant outflow hole642, the lubricant inflow hole643, and the lubricant outflow hole644bore through the joining surface636and the oil cooler attaching face637. A fluid passage cross-sectional area (diameter) of the coolant outflow hole642is smaller than a fluid passage cross-sectional area of the coolant inflow hole641. In the oil cooler bracket631, a lubricant inlet passage645and a lubricant outlet passage646are formed, which extend from the joining surface636of the oil cooler attaching part633to the oil filter attaching surface640of the oil filter attaching part635through the inside of the coupling portion634. The lubricant inlet passage645and the lubricant outlet passage646extend from the joining surface636to the oil filter attaching part635, in a direction perpendicular to the joining surface636. The lubricant inlet passage645is, within the oil filter attaching part635, bent in a direction perpendicular to the oil filter attaching surface640, and is opened at a central position of the oil filter attaching surface640. The lubricant outlet passage646is, within the oil filter attaching part635, coupled to a substantially cylindrical passage formed around the lubricant inlet passage645, and is opened with an annular shape enclosing the lubricant inlet passage645inside the oil filter attaching surface640with an annular shape. As shown inFIG.34, the oil cooler bracket attachment pedestal318is provided with: a coolant outlet647connected to the water rail610(seeFIG.13andFIG.30) provided inside the cylinder block6; a coolant return port648connected to a coolant return passage (not shown) provided inside the cylinder block6; a lubricant outlet649connected to the lubricant supply passage316(seeFIG.11andFIG.13) provided inside the cylinder block6; and a lubricant return port650connected to a lubricant feed passage (not shown) provided inside the cylinder block6. In the oil cooler bracket attachment pedestal318, a coolant inflow passage651, a lubricant inflow passage652, a lubricant relay passage653, and a lubricant outflow passage654are formed. The coolant inflow passage651guides a coolant from the coolant outlet647to the coolant inflow hole641of the oil cooler bracket631. The lubricant inflow passage652guides a lubricant from the lubricant outlet649to the lubricant inflow hole643. The lubricant relay passage653guides a lubricant from the lubricant outflow hole644to the lubricant inlet passage645. The lubricant outflow passage654guides a lubricant from the lubricant outlet passage646to the lubricant return port650. A bypass passage655is formed between the lubricant inflow passage652and the lubricant relay passage653. Each of these passages651,652,653,654,655is constituted of a recessed groove formed in a surface of the oil cooler bracket attachment pedestal318, and, when covered with the joining surface636of the oil cooler bracket631, forms a passage that allows a fluid to circulate therethrough. The bypass passage655is a passage for bypassing a lubricant of the lubricant outlet649from the lubricant inflow passage652to the lubricant relay passage653, in order to prevent an excessive oil pressure rise within the oil cooler13. A groove width and a groove depth of the bypass passage655, which mean a fluid passage cross-sectional area of the bypass passage655, is smaller than that of the lubricant inflow passage652and that of the lubricant relay passage653. The oil cooler bracket attachment pedestal318has, at positions corresponding to the bolt insertion holes638of the oil cooler bracket631, bracket bolt holes656in which the bracket bolts632are inserted. As shown inFIG.32, the joining surface636of the oil cooler bracket631has a seal member accommodating groove657, a seal member accommodating groove658, a seal member accommodating groove659, and a seal member accommodating groove660. While the oil cooler bracket631is attached to the oil cooler bracket attachment pedestal318; the seal member accommodating groove657encloses an outer periphery of the coolant inflow passage651, the seal member accommodating groove658encloses an outer periphery of the coolant return port648, the seal member accommodating groove659encloses an outer periphery of a group of the lubricant inflow passage652, the lubricant relay passage653, and the bypass passage655, and the seal member accommodating groove660encloses an outer periphery of the lubricant outflow passage654. While these seal member accommodating grooves657,658,659,660accommodate seal members (not shown) made of elastic members for example, the oil cooler bracket631is attached to the oil cooler bracket attachment pedestal318, to thereby exert a sealability between the oil cooler bracket631and the oil cooler bracket attachment pedestal318. As shown inFIG.31andFIG.32, the oil cooler attaching face637of the oil cooler bracket631has, in its peripheral edge portion, a plurality of cooler bolt holes661. Cooler bolts662are inserted through bolt insertion holes formed in a peripheral edge portion of the oil cooler13, and are fastened to the cooler bolt holes661, thereby fixing the oil cooler13to the oil cooler bracket631. The oil cooler attaching face637has four circular seal member accommodating grooves663surrounding outer peripheries of the coolant inflow hole641, the coolant outflow hole642, the lubricant inflow hole643, and the lubricant outflow hole644, respectively. The oil cooler13is attached to the oil cooler bracket631with a seal member (not shown) made of an elastic member such as an O-ring accommodated in each seal member accommodating groove663, so that a sealability between the oil cooler13and the oil cooler bracket631is exerted. A female thread provided in a peripheral edge portion of a casing of the oil filter14and a male thread provided in a peripheral edge portion of the oil filter attaching surface640of the oil cooler bracket631are fastened and fixed to each other, so that the oil filter14is attached to the oil filter attaching surface640. The engine1of this embodiment includes the oil cooler bracket631for supporting the oil cooler13and the oil filter14, the oil cooler bracket631being attached to the cylinder block6. The coolant outlet647, the coolant return port648, the lubricant outlet649, and the lubricant return port650are provided in the oil cooler bracket attachment pedestal318of the cylinder block6. Via the oil cooler bracket631, a coolant and a lubricant are circulated in the oil cooler13, and a lubricant is circulated in the oil filter14. Accordingly, the engine1of this embodiment eliminates the need to provide coolant piping to be connected to the oil cooler13and a lubricant pipe member for connecting the oil cooler13to the oil filter14, thus reducing the number of component parts. In addition, since the oil cooler13and the oil filter14are supported by the same oil cooler bracket631, the oil cooler13and the oil filter14can be arranged compactly. Furthermore, since the oil cooler13and the oil filter14are supported by the single oil cooler bracket631, the structure for attaching the oil cooler13and the oil filter14can be simplified. The oil cooler bracket631has the coolant inflow hole641to be connected to the coolant outlet647, and the coolant outflow hole642to be connected to the coolant return port648. The fluid passage cross-sectional area of the coolant outflow hole642is smaller than the fluid passage cross-sectional area of the coolant inflow hole641. This can raise a water pressure in the coolant path that extends from the coolant outlet647provided in the oil cooler bracket attachment pedestal318, through the coolant inflow hole641and the coolant passage provided in the oil cooler13, to the coolant outflow hole642. Accordingly, a phenomenon in which a larger amount of coolant than necessary flows out from the coolant inflow hole641to the coolant return port648to drop the water pressure in the coolant passage provided inside the cylinder block6can be prevented. Thus, a deterioration in the cooling efficiency of the engine1can be prevented. The oil cooler bracket631has, in its oil cooler attaching face637which is parallel to the joining surface636joined to the oil cooler bracket attachment pedestal318, the oil cooler attaching part633to which the oil cooler13is attached, and also has, on the distal end side of the coupling portion634which is provided upright on the oil cooler attaching part633, the oil filter attaching part635to which the oil filter14is attached on the side opposite to the oil cooler13. This allows the oil filter14to protrude substantially in parallel to the right surface302(lateral side portion) of the cylinder block6, which enables the oil cooler13and the oil filter14to be arranged compactly and also enables the oil filter14to protrude from the right surface302of the cylinder block6by a shortened distance, thereby compactifying the engine1. As shown inFIG.36andFIG.37, the oil filter14is supported by the oil cooler bracket631, and therefore a space can be provided between the oil filter14and the right surface302of the cylinder block6. Such a space cannot be obtained by a configuration in which, for example, the oil filter14is directly attached to the cylinder block6. For example, it is possible that the linear portion311aof the right-side second reinforcing rib311is arranged in the space between the right surface302and the oil filter14, to enhance the strength and heat dissipation performance of the cylinder block6, or that the main harness assembly703is passed through the space, to shorten the distance by which the main harness assembly703is guided. The space between the right surface302and the oil filter14can be used for other purposes. In this manner, arranging the oil filter14at a distance from the cylinder block6by using the oil cooler bracket631enhances the degree of freedom in designing the engine1. In addition, arranging the main harness assembly703so as to extend along the linear portion311aof the right-side second reinforcing rib311can eliminate the need to dispose a bracket for placing and arranging the main harness assembly703, and also can protect the main harness assembly703against dust and dirt, etc. coming from below while preventing interference with a foreign object such as another component part. The configurations of respective parts of the present invention are not limited to those of the illustrated embodiment, but can be variously changed without departing from the gist of the invention. REFERENCE SIGNS LIST 1, engine5, crankshaft6, cylinder block7, flywheel housing8, flywheel13, oil cooler14, oil filter20, starter27, EGR cooler30, two-stage turbocharger (turbocharger)300, crankshaft center301, left surface (opposite side portions)302, right surface (opposite side portions)303, front surface (one side portion)304, left housing bracket portion305, right housing bracket portion306,307,308,309,310,311, reinforcing rib307a,308a,309a,311a, linear portion of reinforcing rib318, oil cooler bracket attachment pedestal (attaching part)325, bracket recessed portion341, block upper surface (cylinder head joining surface)344, motor shaft center345, turbocharger lubricant pipe410, starter attachment pedestal631, oil cooler bracket (bracket member)633, oil cooler attaching part634, coupling portion635, oil filter attaching part636, joining surface637, oil cooler attaching face (parallel surface)641, coolant inflow hole642, coolant outflow hole647, coolant outlet648, coolant return port649, lubricant outlet650, lubricant return port | 70,866 |
11859578 | DETAILED DESCRIPTION FIG.1illustrates an aircraft propulsion system20for an aircraft such as, but not limited to, a commercial airliner or a cargo plane. The propulsion system20includes a nacelle22and a gas turbine engine. This gas turbine engine may be configured as a high-bypass turbofan engine. Alternatively, the gas turbine engine may be configured as a turbojet engine or any other type of gas turbine engine capable of propelling the aircraft during flight. The nacelle22is configured to house and provide an aerodynamic cover for the gas turbine engine. An outer structure24of the nacelle22extends axially along an axial centerline26(e.g., a centerline of the propulsion system20, the nacelle22and/or the gas turbine engine) between a nacelle forward end28and a nacelle aft end30. The nacelle outer structure24ofFIG.1includes a nacelle inlet structure32, one or more fan cowls34(one such cowl visible inFIG.1) and a nacelle aft structure36, which is configured as part of or includes a thrust reverser system38(see alsoFIG.2). The inlet structure32is disposed at the nacelle forward end28. The inlet structure32is configured to direct a stream of air through an inlet opening40at the nacelle forward end28and into a fan section of the gas turbine engine. The fan cowls34are disposed axially between the inlet structure32and the aft structure36. Each fan cowl34ofFIG.1, in particular, is disposed at (e.g., on, adjacent or proximate) an aft end42of a stationary portion44of the nacelle22, and extends forward to the inlet structure32. Each fan cowl34is generally axially aligned with the fan section of the gas turbine engine. The fan cowls34are configured to provide an aerodynamic covering for a fan case46. Briefly, the fan case46extends circumferentially around the axial centerline26and thereby circumscribes the fan section. Referring toFIG.3, the fan case46along with the nacelle22form a forward outer peripheral boundary of a forward thrust duct48of the propulsion system20. In the embodiment ofFIG.3, the forward thrust duct48is configured as a bypass duct. The forward thrust duct48ofFIG.3, for example, at least partially or completely forms a bypass flowpath50within the propulsion system20, which bypass flowpath50bypasses (e.g., flows around and/or outside of, not through) a core of the gas turbine engine to a bypass nozzle52. Thus, during nominal propulsion system operation (e.g., when the thrust reverser system38is in its stowed configuration; seeFIG.3), the forward thrust duct48is configured to facilitate forward thrust for the propulsion system20; e.g., direct fluid (e.g., fan/compressed air) out of the propulsion system20through the bypass nozzle52in an axially aft direction. Referring again toFIG.1, the aft structure36includes a translating sleeve54for the thrust reverser system38. The translating sleeve54ofFIG.1is disposed at the nacelle aft end30. This translating sleeve54extends axially along the axial centerline26between a forward end56of the translating sleeve54and the nacelle aft end30. The translating sleeve54is configured to partially form an aft outer peripheral boundary of the forward thrust duct48and its flowpath50(seeFIG.3). The translating sleeve54may also be configured to form the bypass nozzle52for the bypass flowpath50with an inner structure58of the nacelle22(e.g., an inner fixed structure (IFS)), which nacelle inner structure58houses the core of the gas turbine engine. Briefly, the turbine engine core typically includes a compressor section, a combustor section and a turbine section of the gas turbine engine. The translating sleeve54ofFIG.1includes a pair of sleeve segments60(e.g., halves) arranged on opposing sides of the propulsion system20(one such sleeve segment visible inFIG.1). The present disclosure, however, is not limited to such an exemplary translating sleeve configuration. For example, the translating sleeve54may alternatively have a substantially tubular body. For example, the translating sleeve54may extend more than three-hundred and thirty degrees)(330° around the axial centerline26. Referring toFIGS.1and2, the translating sleeve54is an axially translatable structure. Each translating sleeve segment60, for example, may be slidably connected to one or more stationary structures (e.g., a pylon and a lower bifurcation) through one or more respective track assemblies. Each track assembly may include a rail mated with a track beam; however, the present disclosure is not limited to the foregoing exemplary sliding connection configuration. Referring toFIGS.3and4, the translating sleeve54is configured with (e.g., coupled to) one or more actuators61(e.g., linear actuators); see alsoFIG.5. These actuators61are configured to move the translating sleeve54axially along the axial centerline26and relative to the stationary portion44. More particularly, the actuators61are configured to axially translate the translating sleeve54between a forward stowed position (seeFIGS.1and3) where the thrust reverser system38is in the stowed configuration and an aft deployed position (seeFIGS.2and4) where the thrust reverser system38is in a deployed configuration. In the forward stowed position ofFIG.3, the translating sleeve54provides the functionality described above. In the aft deployed position ofFIG.4, the translating sleeve54opens one or more thrust reverser ducts62(one visible inFIG.4). Each of these thrust reverser ducts62extends radially through the nacelle outer structure24from a respective thrust reverser duct inlet64to a respective thrust reverser duct outlet66. The thrust reverser duct inlet64is located radially adjacent the forward thrust duct48. The thrust reverser duct inlet64fluidly couples the respective thrust reverser duct62with the forward thrust duct48when the thrust reverser system38is in its deployed configuration. In the aft deployed position ofFIG.4, the translating sleeve54also uncovers one or more additional components of the thrust reverser system38. The translating sleeve54ofFIG.4, for example, uncovers one or more cascade structures68(e.g., cascade halves) (one cascade structure visible inFIGS.2and4). In addition, as the translating sleeve54moves from the stowed position to the deployed position, one or more blocker door assemblies70(e.g., arcuate arrays of blocker doors72A-E (generally referred to as “72”); e.g., seeFIG.5) are deployed. Each blocker door assembly70is configured to divert the fluid (e.g., fan/compressed air) from the forward thrust duct48and its flowpath50into a respective one of the thrust reverser ducts62and through a respective one of the cascade structures68to provide reverse thrust for the propulsion system20; e.g., direct the fluid out of the propulsion system20through the thrust reverser duct outlets66generally in an axially forward direction and/or a radially outward direction. Referring toFIG.5, each cascade structure68includes a plurality of cascade segments74A-H (generally referred to as “74”). Each of these cascade segments74may be configured as a cascade basket. For example, referring toFIG.6, each cascade segment74extends axially along the axial centerline26between and to a first (e.g., forward and/or upstream) end76and a second (e.g., aft and/or downstream) end78. Each cascade segment74extends laterally (e.g., circumferentially or tangentially) between and to opposing sides80A and80B (generally referred to as “80”). Referring toFIG.7, each cascade segment74extends vertically (e.g., radially) between and to a first (e.g., radial inner and/or upstream) side82and a second (e.g., radial outer and/or downstream) side84. The cascade segment74ofFIGS.6and7includes a base cascade structure86and one or more attachments88and90; e.g., mounting structures. Each of these attachments88and90is configured to attach/mount the cascade segment74and, thus, the respective cascade structure68to another structure of the propulsion system20such as, but not limited to, a forward structural beam92(e.g., the torque box) or an aft cascade ring94(seeFIG.4). The attachments88and90ofFIGS.6and7, for example, are configured as attachment flanges. The first (e.g., forward and/or upstream) attachment88is arranged at the cascade structure first end76. The second (e.g., aft and/or downstream) attachment90is arranged at the cascade structure second end78. Referring toFIG.6, the base cascade structure86includes a plurality of strongback rails96and one or more arrays97of cascade vanes. The strongback rails96ofFIG.6are arranged parallel with one another. The strongback rails96are connected to the attachments88and90. The strongback rails96ofFIG.6, for example, extend axially along the axial centerline26between and to the cascade attachments88and90. Referring toFIG.8, one or more or each of the strongback rails96may have a straight, linear sectional geometry when viewed, for example, in a plane perpendicular to the axial centerline26; e.g., the plane ofFIG.8. Each strongback rail96, for example, may extend along a straight, substantially (e.g., completely) radial centerline. With such an arrangement, the respective cascade segment74may direct fluid along a radial outward trajectory100A-H (generally referred to as “100”; see alsoFIG.5) with no or a relatively small circumferential component. However, referring toFIGS.9A and9B, the cascade segment74and one or more or each of its strongback rails96may alternatively be configured to direct the fluid in a circumferential direction. The radial outward trajectory100, more particularly, may have a circumferential component; a clockwise or counter-clockwise component. Each strongback rail96ofFIGS.9A and9B, for example, extends along a non-linear (e.g., curved, arcuate, splined, concave) centerline when viewed, for example, in a plane perpendicular to the axial centerline26; e.g., the plane ofFIGS.9A and9B. Of course, in other embodiments, one or more or each of the strongback rails96may have a straight centerline that is angularly offset from a radial line. Referring toFIG.6, the arrays97of cascade vanes are respectively arranged between laterally adjacent strongback rails96. Each of the arrays97of cascade vanes includes a plurality of the cascade vanes98(only a select few of which are labeled inFIGS.6and7for ease of illustration), which cascade vanes98are disposed at discrete locations along an axial length of the strongback rails96. These cascade vanes98are configured to turn a flow of fluid (e.g., air) forward, thereby reversing the thrust of the engine fan stream, and aiding in reducing speed (e.g., stopping) of the aircraft. Each axially adjacent pair of vanes98forms a respective flow passage102axially therebetween. Similarly, each forwardmost and/or upstream-most cascade vane98forms a respective flow passage102with the first attachment88. Each aftmost and/or downstream-most cascade vane98forms a respective flow passage102with the second attachment90. A degree of forward turning may vary between the cascade segments74A to74H. For example, the degree of forward turning angle at a bottom of the nacelle (e.g., towards the cascade segment74H) may be less than the degree of forward turning angle at a top of the nacelle (e.g., towards the cascade segment74A). An effective flow area of the cascade segment may depend on the forward turning angle. Each of the cascade vanes98is connected to a respective adjacent set of the strongback rails96. Each cascade vane98ofFIG.6, for example, extends laterally between and to a respective adjacent set of the strongback rails96. Each of the flow passages102ofFIG.6therefore extends laterally between a respective pair of the strongback rails96. Referring toFIG.10, one or more or each of the cascade vanes98may have a non-linear (e.g., curvilinear) cross-sectional geometry when viewed, for example, in a plane parallel with the axial centerline26; e.g., the plane ofFIG.10. Each cascade vane98, for example, may extend along a non-linear (e.g., curved, arcuate, splined, concave) centerline. With such an arrangement, each cascade segment74and its cascade vanes98may axially redirect the fluid flowing through the respective cascade segment74. The cascade vanes98ofFIG.10, for example, are configured to turn the fluid flowing through the respective cascade segment74to provide the radial outward trajectory100with an axial forward component. In another example, the cascade vanes98ofFIG.11are configured to turn the fluid flowing through the respective cascade segment74to provide the radial outward trajectory100with no or a relatively small axial component. The present disclosure, however, is not limited to the foregoing exemplary cascade vane configurations. For example, in other embodiments, the cascade vanes98may be configured to provide the radial outward trajectory100with an axial aft component that is less than an axial aft component of a trajectory of the fluid entering the respective cascade segment74from the forward thrust duct48. Referring toFIG.5, the cascade segments74in each cascade structure68are arranged circumferentially about the axial centerline26in an arcuate array. The cascade segment74A ofFIG.5circumferentially neighbors (e.g., is adjacent, abuts, etc.) a first (e.g., upper) bifurcation104of the forward thrust duct48. The cascade segment74H ofFIG.5circumferentially neighbors a second (e.g., lower) bifurcation106of the forward thrust duct48. The cascade segments74B-G are arranged one-by-one around the axial centerline26and sequentially between the end cascade segments74A and74H. Each of the cascade segments74is configured with a respective cascade segment flow area; e.g., the effective flow area. The term “cascade segment flow area” may describe a total flow area through the respective cascade segment74. For example, the cascade segment flow area of the cascade segment74ofFIG.6is equal to a sum of the flow areas (e.g., cross-sectional areas) of all the flow passages102through that respective cascade segment74. The flow area of each flow passage102may be measured in a lateral (e.g., circumferential or tangential) plane that extends through and/or along the cascade segment74and at, for example, an outlet107(e.g., an exit) of the respective flow passage102. Referring toFIG.7, this plane may be measured normal to a flow direction109out of the respective outlet107; e.g., see plane111. The flow direction109at the outlet107is related to the turning angle of a respective cascade vane (e.g.,98A). The flow direction109at the outlet107, for example, may be parallel with a pressure side surface (e.g.,113) of the respective cascade vane (e.g.,98A) at or about the outlet107. In the specific embodiment ofFIG.5, each of the cascade segments74may have the cascade segment flow areas outlined in TABLE 1 below. Cascade SegmentCircumferentialCascade SegmentFlow AreaFlow componentSegment 74A1.75X to 1.90XNone/radialSegment 74B1.30X to 1.50XFirst circumferentialcomponentSegment 74CXFirst circumferentialcomponentSegment 74D1.65X to 1.85XSecond circumferentialcomponentSegment 74E1.65X to 1.85XSecond circumferentialcomponentSegment 74F1.65X to 1.85XSecond circumferentialcomponentSegment 74G1.65X to 1.85XFirst circumferentialcomponentSegment 74H1.30X to 1.50XFirst circumferentialcomponent The present disclosure, however, is not limited to the exemplary arrangement and/or ratios of cascade segment flow areas in TABLE 1. For example, in some embodiments, the cascade segment flow area of any one of the cascade segments74may be equal to or greater than 1.2X or 1.4X (e.g., as much as or greater than 2.0X), where X is the cascade segment flow area of any other one of the cascade segments74. In addition or alternatively, the cascade segment flow area of any one of the cascade segments74may be equal to or greater than 1.5X or 1.7X, where X is the cascade segment flow area of any other one of the cascade segments74. The value X may be between fifty square inches (50 in2) and one-hundred and seventy-five square inches (175 in2). Of course, in other embodiments, the value X may be less than fifty square inches (50 in2) or greater than one-hundred and seventy-five square inches (175 in2). Each of the cascade segments74A-H ofFIG.5is configured to direct the fluid along a respective radial outward trajectory100A-H as described above. The radial outward trajectory100associated with any one or more or all of the cascade segments74(e.g., the cascade segment74A) may have little or no circumferential flow component/direction; e.g., see alsoFIG.8. In addition or alternatively, the radial outward trajectory100associated with any one or more or all of the cascade segments74(e.g., the cascade segments74B,74C,74G and74H) may have a first (e.g., counter-clockwise) circumferential component/direction; e.g., see alsoFIG.9A. In addition or alternatively, the outward trajectory100associated with any one or more or all of the cascade segments74(e.g., the cascade segments74D-F) may have a second (e.g., clockwise) circumferential component/direction; e.g., seeFIG.9B. The present disclosure, of course, is not limited to the circumferential flow component relationships outlined in TABLE 1. The effective flow area of the cascade segment may also depend on the circumferential turning angle. Each of the cascade segments74ofFIG.5has a respective cascade segment configuration. This cascade segment configuration is defined by various parameters including, but not limited to: a size (e.g., axial length, lateral width, etc.) of the cascade segment74; turning angles of the cascade vanes98within the cascade segment74; turning angles of the strongback rails96within the cascade segment74; orientation of the cascade segment74; etc. Any one or more or all of the foregoing parameters may be the same or different for some or all of the cascade segments74. More particularly, one or more of the cascade segments74may have a common cascade segment configuration. One or more of the cascade segments74may also or alternatively have a different (e.g., unique) cascade segment configuration. For example, the cascade segments74D-F may share a common cascade segment configuration. Each of the cascade segments74A-C,74G and74H may have a unique cascade configuration. The present disclosure, however, is not limited to such an arrangement of cascade segments. The blocker door assembly70ofFIG.5includes the plurality of blocker doors72. Referring toFIG.12, each of the blocker doors72extends longitudinally between and to a first end108and a second end110. The blocker door first end108may be an axially forward end when the respective blocker door72is in its stowed position (seeFIG.3) and/or a radial outer end when the respective blocker door72is in its deployed position (seeFIG.4). The blocker door second end110may be an axially aft end when the respective blocker door72is in its stowed position (seeFIG.3) and/or a radial inner end when the respective blocker door72is in its deployed position (seeFIG.4). Each blocker door72ofFIG.12extends laterally (e.g., tangentially or circumferentially when stowed) between opposing sides112and114. Each blocker door72A-E ofFIG.5has a blocker door surface116A-E (generally referred to as “116”). Referring toFIG.3, this blocker door surface116may be configured to partially form the aft outer peripheral boundary of the forward thrust duct48and its flowpath50when the respective blocker door72is in its stowed position. Referring toFIG.4, the blocker door surface116is configured to form a turning surface/a barrier surface within the forward thrust duct48and its flowpath50when the respective blocker door72is in its deployed position. The blocker door surface116is thereby operable to redirect a portion of the axially aft flowing fluid within the forward thrust duct48radially outward into the respective thrust reverser duct62and one or more respective cascade segments74. The blocker door surface116ofFIG.12is bounded longitudinally by the blocker door first end108and the blocker door second end110. The blocker door surface116is bounded laterally by the opposing blocker door sides112and114. At least a portion or an entirety of the blocker door surface116may be a tapered surface. A lateral width118of the blocker door72and its surface116, for example, may laterally taper as the blocker door72and its surface116extends longitudinally towards the blocker door second end110; e.g., from the blocker door first end108and/or to the blocker door second end110. This taper may be symmetrical relative to a longitudinal centerline120of the blocker door72. For example, the blocker door second end110and the blocker door first side112are angularly offset by an included first angle122at, for example, a corner between the blocker door elements110and112. The blocker door second end110and the blocker door second side114are angularly offset by an included second angle124at, for example, a corner between the blocker door elements110and114, where the second angle124may be equal to the first angle122. A length126of the blocker door first side112may also be equal to a length128of the blocker door second side114. A contour/shape of the blocker door first side112may also be the same as a contour/shape of the blocker door second side114, etc. Alternatively, referring toFIG.13, the taper may be asymmetrical relative to the longitudinal centerline120of the blocker door72. For example, the second angle124may be different (e.g., greater, or less) than the first angle122. The length126of the blocker door first side112may also or alternatively be different (e.g., less or greater) than the length128of the blocker door second side114. The contour/shape of the blocker door first side112may also or alternatively be the different than the contour/shape of the blocker door second side114, etc. Referring toFIG.12, each of the blocker doors72has a blocker door configuration. This blocker door configuration may be defined by various parameters including, but not limited to: surface area and/or perimeter shape of the blocker door surface116; the lateral width118of the blocker door72at the blocker door first end108; the lateral width118of the blocker door72at the blocker door second end110; a longitudinal length130of the blocker door72; the contour, the shape and/or the length126of the blocker door first side112; the contour, the shape and/or the length128of the blocker door second side114; the first angle122; the second angle124; etc. Any one or more or all of the foregoing parameters may be the same or different for some or all of the blocker doors72. More particularly, one or more of the blocker doors72may have a common blocker door configuration. One or more of the blocker doors72may also or alternatively have a different (e.g., unique) blocker door configuration. For example, referring toFIG.5, the lateral widths at the first (e.g., outer) ends of the blocker doors72A-72E may be equal. The lateral widths at the second (e.g., inner) ends of the blocker doors72A,72B and72E may be equal. The lateral widths at the second (e.g., inner) ends of the blocker doors72C and72D may also be equal, and greater than the lateral widths at the second (e.g., inner) ends of the blocker doors72A,72B and72E. The longitudinal lengths of the blocker doors72A-72E may be equal. The blocker doors72A,72B and72E may be asymmetric tapered doors, whereas the blocker doors72C and72D may be symmetric tapered doors. The first angle of the blocker door72A may be equal to the second angles of the blocker doors72C and72D. The second angle of the blocker door72A may be equal to the first angles of the blocker doors72B and72E. The first angles of the blocker doors72C and72D may be equal, and the second angles of the blocker doors72C and72D may be equal. SeeFIGS.12and13for reference to at least some of the dimensions discussed above. The blocker doors72ofFIG.5are arranged circumferentially about the axial centerline26in an arcuate array. The blocker door72A ofFIG.5is laterally (e.g., circumferentially) next to the first bifurcation104of the forward thrust duct48. The blocker door72E ofFIG.5is laterally (e.g., circumferentially) next to the second bifurcation106of the forward thrust duct48. The blocker doors72B-D are arranged one-by-one around the axial centerline26and sequentially between the end blocker doors72A and72E. Referring toFIGS.3and4, each of the blocker doors72is configured to move (e.g., pivot radially inward towards the axial centerline26) from its stowed position (seeFIG.3) to its deployed position (seeFIG.4). In the deployed position ofFIG.4, each blocker door72redirects at least some of the fluid from the forward thrust duct48into a respective one of the thrust reverser ducts62and one or more of the cascade segments74. More particularly, when the blocker doors72of are deployed as shown inFIGS.14and15, a portion (e.g., a majority) of the fluid flowing within the forward thrust duct48is redirected into the thrust reverser ducts62and through the cascade structures68to produce reverse thrust. However, referring toFIG.15, some fluid may leak past the cascade structures68. Some of the fluid, for example, may leak around the cascade segments74A-H; e.g., through gaps between laterally neighboring cascade segments (e.g., between74A and74B, between74B and74C, etc.) through cavities accommodating the actuators61, etc. Some additional fluid may also or alternatively leak past each blocker door assembly70. Some of the fluid, for example, may leak around the blocker doors72A-E; e.g., through lateral gaps between laterally neighboring blocker doors (e.g., between72A and72B, between72B and72C, etc.), through respective lateral gaps between blocker doors72A and72E and the bifurcations104and106, through radial gaps between the blocker doors72A-E and nacelle inner structure58(see alsoFIG.14), through radial gaps between the blocker doors72A-E and the nacelle outer structure (e.g., the cascade structure68) (see alsoFIG.14), etc. Each cascade structure68is associated with a plurality of lateral sectors132A-G (e.g., circumferential sectors) (generally referred to as “132”) of an assembly. In particular, each cascade segment74A-H is associated with/defines a respective one of the lateral sectors132. For example, lateral (e.g., circumferential) bounds of each cascade segment74define radial lines to the centerline26, which radial lines may form lateral bounds of the respective lateral sector132. Each of these lateral sectors132has an effective axial leakage flow area, an effective radial leakage flow area and an effective total flow area. The axial leakage flow area represents a flow area of leakage path(es) about the blocker door assembly70(e.g., one or more of the blocker doors72) within a respective lateral sector132. The flow area of each axial leakage path may be measured in a plane perpendicular to the axial centerline26, and/or in a plane normal to the respective axial leakage path. The radial leakage flow area represents a flow area of leakage path(es) about the cascade structure68(e.g., a respective one of the cascade segments74) within a respective lateral sector132. The flow area of each radial leakage path may be measured in a lateral (e.g., circumferential or tangential) plane that extends through and/or along a respective cascade segment74and extends circumferentially about the axial centerline26, and/or in a plane normal to the respective radial leakage path. The total flow area may be calculated by adding the axial leakage flow area, the radial leakage flow area and the cascade segment flow area for a respective lateral sector132. Note, any one or more of the axial leakage flow area, the radial leakage flow area and/or the cascade segment flow area may incorporate a respective discharge coefficient to account for various flow properties such as, but not limited to, flow separation. For example, the sum of the axial leakage path flow area(s) (or each flow area) may be multiplied by a respective discharge coefficient to provide the axial leakage flow area. During thrust reverser system operation, the fluid flowing from the forward thrust duct48to the thrust reverser ducts62may be subject to primary flows and secondary flows. The term “primary flow” may describe a fluid trajectorial component in an axial or radial direction. For example, the primary flows of the fluid may travel axially within the forward thrust duct48and radially within the thrust reverser duct62. The term “secondary flow” may describe a fluid trajectorial component in a lateral (e.g., circumferential or tangential) direction. For example, secondary flows of the fluid may travel laterally within the forward thrust duct48and/or the thrust reverser duct62. The secondary flows may be generated by a tendency of the fluid to travel along a path of least resistance. For example, where a first of the cascade segments74has a greater cascade segment flow area than a neighboring second of the cascade segments74, some of the fluid laterally aligned with the second cascade segment may have a tendency to turn laterally towards the first cascade segment. Similarly, where leakage passages about a first of the cascade segments74and/or a first of the blocker doors72are smaller than leakage passages about a neighboring second of the cascade segments74and/or a neighboring second of the blocker doors72, some of the fluid laterally aligned with the first cascade segment and/or the first blocker door may have a tendency to turn laterally towards the second cascade segment and/or the second blocker door. In addition, where one of the cascade segments74(e.g., the first cascade segment) is next to a flow impediment and/or a flow diverter such as, but not limited to, one of the bifurcations, some of the fluid laterally aligned with that flow impediment/diverter may have a tendency to turn laterally towards the cascade segment74and/or the associated blocker door. Generation of the secondary flows within the fluid may decrease efficiency of the aircraft propulsion system20and, more particularly, the thrust reverser system38. Therefore, to reduce the generation of the secondary fluid flows and thereby increase thrust reverser efficiency, the thrust reverser system38of the present disclosure may be configured such that the total flow areas of at least some of the laterally neighboring lateral sectors132are performance matched. An example of such performance matching is outlined below in TABLE 2. TABLE 2Circumferential SectorEffective Total Flow AreaSector 132A185% to 200% of Y1.85Y to 2.00YSector 132B105% to 115% of Y1.05Y to 1.15YSector 132CYYSector 132D110% to 120% of Y1.10Y to 1.20YSector 132E105% to 115% of Y1.05Y to 1.15YSector 132F105% to 115% of Y1.05Y to 1.15YSector 132G115% to 125% of Y1.15Y to 1.25YSector 132H150% to 165% of Y1.50Y to 1.65Y The present disclosure, however, is not limited to the exemplary arrangement and/or ratios of total flow areas in TABLE 2. For example, in some embodiments, the total flow area of any one of the lateral sectors132may be within (+/−) five, eight or ten percent (5, 8 or 10%) of Y, where Y is the total flow area of any other one of the lateral sectors132. In addition or alternatively, the total flow area of any one of the lateral sectors132may be within (+/−), fifteen, twenty or twenty-five percent (15, 20 or 25%) of Y, where Y is the total flow area of any other one of the lateral sectors132. In the exemplary embodiment of TABLE 2, the total flow areas of the intermediate lateral sectors132B-G are within (+/−) five, ten, fifteen or twenty percent (5, 10, 15 or 20%) of one another. By contrast, the total flow areas of the end lateral sectors132A and132H are more than one-hundred and fifty percent (150%) of the total flow area of one or more of the intermediate lateral sectors132B-G. This discrepancy in flow areas may be provided such that the end lateral sectors132A and132H can accommodate additional fluid flow associated with, for example, the additional fluid laterally diverted into those sectors132A and132H by the first and the second bifurcations104and106. The total flow area of a respective lateral sector132can be increased by, for example, decreasing the surface area of a respective blocker door72and its blocker door surface116. For example, the blocker door72A ofFIG.5is trimmed to increase the axial leakage flow area thereabout and, thus, increase the total flow area within the respective lateral sector132A. Conversely, the total flow area of a respective lateral sector132can be decreased by, for example, increasing the surface area of a respective blocker door72and its blocker door surface116. For example, the blocker door72C ofFIG.5is extended to decrease the axial leakage flow area thereabout and, thus, decrease the total flow area within the respective lateral sector132D,132E. The cascade segment flow areas and/or the radial leakage flow areas may also or alternatively be adjusted to provide total flow area performance matching. FIG.16illustrates the blocker door assembly70with another arrangement of the blocker doors72. In the embodiment ofFIG.16, each of the blocker doors72A-E has a different configuration; e.g., a different shape and/or dimensions. This blocker door assembly70may provide even closer performance matching between the total flow areas of the different lateral sectors132A-H. Referring toFIG.16, any one of the lateral sectors132(e.g.,132B-G) may have a lateral width134A-H (generally referred to as “134”) (e.g., circumferential width) that is substantially equal to the lateral width134of any other one of the lateral sectors132(e.g.,132B-G). The lateral widths134of some or all of the lateral sectors132(e.g.,132B-G), for example, may be exactly or approximately (e.g., +/−2%) equal to one another. Alternatively, the lateral width134of any one or more of the lateral sectors132(e.g.,132B-G) may be different than the lateral width134of any other one or more of the lateral sectors132(e.g.,132A,132H). While the gas turbine engine is generally described above as a turbofan turbine engine, the present disclosure is not limited to such an exemplary gas turbine engine configuration. For example, in other embodiments, the gas turbine engine may alternatively be configured as a turbojet gas turbine engine where, for example, the forward thrust duct48is configured as a core duct and/or an exhaust duct rather than a bypass duct. The present disclosure therefore is not limited to any particular gas turbine engine types or configurations. Furthermore, the present disclosure is not limited to a translating sleeve type thrust reverser. While various embodiments of the present invention have been disclosed, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. For example, the present invention as described herein includes several aspects and embodiments that include particular features. Although these features may be described individually, it is within the scope of the present invention that some or all of these features may be combined with any one of the aspects and remain within the scope of the invention. Accordingly, the present invention is not to be restricted except in light of the attached claims and their equivalents. | 35,378 |
11859579 | Unless otherwise indicated, similar reference characters denote corresponding features consistently throughout the attached drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS Some embodiments of the present invention pertain to a system that enables multiple burns from a solid fuel rocket motor. Rather than using a one-use ignition system as in conventional solid rockets, for example, some embodiments employ a multi-use ignition system that can reignite the rocket at least two times, and in some embodiments, many times. For example, in some embodiments, 10-20 burns may be possible since this should be able to accomplish most maneuvers. However, any desired number of burns may be possible without deviating from the scope of the invention. In certain embodiments, a non-damaging extinguishing system is included that is capable of extinguishing the rocket via rapid decompression and then returning the rocket to a configuration where it can be reignited. Some embodiments of the present invention pertain to a decompressive extinguishing plug nozzle that can extinguish solid rocket fuel after the rocket has been ignited and/or keep a rocket in a disarmed (zero thrust) state until the rocket is to be armed. Certain embodiments provide a non-damaging extinguishing system including a nozzle with a mechanically variable throat. This mechanically variable throat affects rapid decompression of the combustion chamber, resulting in extinguishing of the burn. The nozzle may then be returned to the “active” configuration shortly thereafter, or whenever desired. The nozzle may include a plug that partially impedes the opening of the nozzle and an outer cowl that is movable to rapidly decompress the combustion chamber, changing the open area of the mechanically variable throat. The decompressive extinguishing plug nozzle of some embodiments may be useful for terrestrial or space solid fuel rocket propulsion systems of any desired size, complexity, and/or application without deviating from the scope of the invention. For terrestrial applications, for example, such a decompressive extinguishing plug nozzle has the added benefit of reduced dependency of exhaust expansion on altitude during atmospheric flight. In some embodiments, the rocket may be kept in a disarmed, decompressive configuration for added safety against an accidental impulsive firing. The general concept would be to arm the system by pulling in the cowl prior to firing the rocket. Such a nozzle may be used just for this safety/arming purpose regardless of extinguishing in certain embodiments. Solid rocket systems have various benefits over liquid rocket systems, such as being less complex, reliable, low cost, and capable of fully fueled storage for long periods of time. Solid rocket systems may also be safer than liquid rocket systems. Safety may be of particular importance for relatively small space vehicles that are typically launched together in a dispenser or other delivery system, such as CubeSats. In such missions, risks to the primary mission are not tolerated, which limits the materials that may be used for propulsion on orbit (e.g., for maneuvers or to place the space vehicle into a higher or lower orbit). Also, long and indeterminate storage times are often required and/or a significant time on orbit may occur prior to thrusting. Furthermore, the scalability of solid rockets provides an advantage. Since solid rockets typically have little valving, piping, pumps, etc. as compared to liquid rockets, solid rockets can be scaled over a large range in fine increments to emphasize different desired characteristics. Small space vehicles are being applied to an increasingly diverse set of commercial, national security, and science missions. This begets a corresponding demand for diversity in propulsion system capability. Virtually any orbit maneuver that a satellite or other space vehicle may need to perform requires multiple burns. Furthermore, to be practical, multiple independently controllable pulses with good impulse are typically required. Solid rocket systems provide relative safety, low cost, low power, scalability, the ability to be stored for long periods of time, the lack of a requirement for pressurized tanks, and good impulse. Conventional solid rockets systems are not suitable for such applications since they provide only a single burn at a fixed impulse per motor. However, the system of some embodiments enables a suitable solid rocket motor to be extinguished and then subsequently reignited, if desired. FIG.1is an architectural diagram illustrating a solid rocket multiple burn system100, according to an embodiment of the present invention. System100includes a water reservoir110that provides a base source for hydrogen (H2) and oxygen (O2), which are separated from the water molecules via a proton exchange membrane (PEM) electrolyzer120. Electrolyzer120includes electrodes (e.g., electrodes produced via chemical vapor decomposition (CVD)) that are supplied with current from batteries194to perform electrolysis. Nonlimiting example embodiments of electrolyzers400,500are shown inFIGS.4and5, respectively. However, it should be noted that any suitable electrolyzer may be used without deviating from the scope of the invention. The separated hydrogen130and oxygen140are then supplied to an igniter150. In some embodiments, water reservoir110and electrolyzer120are not included. Instead, hydrogen and oxygen are supplied by respective storage tanks130,140. Igniter150in this embodiment is a catalytic igniter that recombines the gaseous hydrogen and oxygen on a catalyst bed (see, e.g.,FIGS.6A and6B). The catalyst bed could be alumina with approximately 10% iridium, a precious metal catalyst, or any other suitable catalyst capable of causing high temperatures and igniting the hydrogen and oxygen without deviating from the scope of the invention. Igniter150may also be a spark igniter (see, e.g.,FIGS.7A and7B) that directly ignites the gaseous hydrogen and oxygen. Indeed, any suitable igniter that can survive the associated temperatures and pressures (e.g., temperatures of 2,000° C. to 3,000° C. or more and pressures of 700 to 1,500 pounds per square inch (psi) or more) may be used without deviating from the scope of the invention. The igniter may be constructed from a high temperature steel alloy, a metalized ceramic, or any other suitable high temperature material(s) without deviating from the scope of the invention. The ignited hydrogen and oxygen then ignite solid fuel160, which then burns in concert with an oxidizer170. In some embodiments, fuel160may be a triaminoguanidine nitrate (TAG-N) base with flake aluminum powder bound together with a glycidyl azide polymer (GAP). However, any suitable solid rocket fuel(s) may be used without deviating from the scope of the invention. In certain embodiments, oxidizer170may include a catalyst that includes, but is not limited to, micron and nanoscale particles of the oxides of Fe, Ni, Cr, Ti, Cu, Bi, Co, Mn, Pd, Pt, Zn, Mg, Ca, rare Earth metals, metal permanganates (alkali, alkali Earth, rare Earth, and transition), chromates, chromites, ferrates, ferrites, metallocenes (e.g., ferrocene, ruthenocene, etc.), substituted metallocenes, or any combination thereof. The fuel and/or oxidizer may be a segmented solid fuel solid oxidizer system (e.g., that of U.S. patent application Ser. No. 15/259,086) or any desired composite monopropellant in some embodiments. Initially, a decompressive nozzle180is set to an active configuration that is appropriate to balance the rate of product mass creation from the burning in combustion chamber120with the desired pressure within combustion chamber120needed to achieve the desired high impulse burn. Alternatively, decompressive nozzle180may be set to a sealed configuration that allows gas to build up in combustion chamber120. Once sufficient gas pressure builds for ignition, decompressive nozzle180may then transition to the active configuration where exhaust gases can escape combustion chamber120via decompressive nozzle180once the rocket motor is ignited. It should be noted that any suitable decompressive nozzle may be used without deviating from the scope of the invention, so long as the decompressive nozzle is capable of rapidly decompressing the combustion chamber to extinguish the burn and of resetting to the active configuration. Once a desired impulse is achieved for the current burn, this is detected via a computing system190in communication with an accelerometer192. Computing system190is configured to control the operation of electrolyzer120, igniter150, and decompressive nozzle180. In some embodiments, computing system190and accelerometer192, and battery194are computing system1500, accelerometer(s)1545, and batteries1540ofFIG.15. The dashed box around computing system190, accelerometer192, and batteries194is intended to indicate that these components are at a different location than what is depicted inFIG.1(e.g., in a different location on the solid rocket motor, in an associated space vehicle, etc.). In certain embodiments, computing system190may be on the ground or on a different space vehicle, and may communicate with accelerometer192and components of system100wirelessly. FIGS.2A and2Bare side cutaway views illustrating a solid rocket motor200with a multiple burn system, according to an embodiment of the present invention. Solid rocket motor200includes a rocket body210and a combustion chamber220. Combustion byproducts flow in the direction of the arrow at the center of combustion chamber220. A water reservoir230provides a base source for hydrogen (H2) and oxygen (O2), which are separated from the water molecules via an electrolyzer240. Electrolyzer240includes electrodes (e.g., electrodes produced via chemical vapor decomposition (CVD)) that are supplied with current from a battery to perform electrolysis. Nonlimiting example embodiments of electrolyzers400,500are shown inFIGS.4and5, respectively. However, any suitable electrolyzer may be used without deviating from the scope of the invention. The separated hydrogen and oxygen are then supplied to an igniter250via a hydrogen feed line252and an oxygen feed line254, respectively. Igniter250may be a catalytic igniter (see, e.g.,FIGS.6A and6B) that recombines the gaseous hydrogen and oxygen on a catalyst bed capable of causing high temperatures and igniting the hydrogen and oxygen. Igniter250may also be a spark igniter (see, e.g.,FIGS.7A and7B) that directly ignites the gaseous hydrogen and oxygen. The igniter should survive the temperatures and pressures of multiple burns (e.g., temperatures of 2,000° C. to 3,000° C. or more and pressures of 700 to 1,500 pounds per square inch (psi) or more). The ignited hydrogen and oxygen then ignite solid fuel260, which then burns in concert with an oxidizer270. Initially, a decompressive extinguishing nozzle, such as decompressive extinguishing plug nozzle280, is set to an active configuration (or to a sealed configuration before the active configuration that allows gas to build in combustion chamber220before transitioning to the active configuration) that is appropriate to balance the rate of product mass creation from the burning in combustion chamber220with the desired pressure within combustion chamber220needed to achieve the desired high impulse burn. It should be noted that any suitable decompressive extinguishing nozzle may be used without deviating from the scope of the invention, so long as the decompressive extinguishing nozzle is capable of rapidly decompressing combustion chamber220to extinguish the burn and of resetting to the active configuration (or to the sealed configuration before the active configuration). The active configuration of decompressive extinguishing plug nozzle280is shown inFIGS.2A and2B. The sealed configuration appears similar, but decompressive extinguishing plug nozzle280is sealed instead of allowing gas to flow out. Once a desired impulse is achieved for the current burn, this is detected via a computing system290in communication with an accelerometer292. Computing system290is configured to control the operation of electrolyzer240, igniter250, and decompressive extinguishing nozzle280. In some embodiments, computing system290and accelerometer292are computing system1500and accelerometer(s)1545ofFIG.15. The dashed box around computing system290and accelerometer292is intended to indicate that these components are at a different location than what is depicted inFIGS.2A and2B(e.g., in a different location on solid rocket motor200, in an associated space vehicle, etc.). In certain embodiments, computing system290may be on the ground or on a different space vehicle, and may communicate with accelerometer292and components of rocket engine200wirelessly. Computing system290extinguishes solid rocket motor200by controlling decompressive extinguishing plug nozzle280to cause a rapid decompression of the combustion chamber. InFIG.2A, a plug281of a decompressive extinguishing plug nozzle280is fixed and an outer cowl286is movable, whereas inFIG.2B, outer cowl286is fixed and plug281is movable. InFIG.2A, cowl286is a single unit, forming both a cowl and cowl housing. However, in some embodiments, the cowl and cowl housing are separate, but attached, components. With reference toFIG.2A, decompressive extinguishing plug nozzle280in this embodiment includes a plug281housed within a plug housing284inside rocket body210. Plug281includes a plug seal282that seals plug281from combustion chamber220, with the exception of holes283in plug seal282that allow exhaust to escape combustion chamber220. Decompressive extinguishing plug nozzle280includes a plug ring285surrounding a bottom portion of plug281and outer cowl286that surrounds plug ring285and contacts plug housing284. In some embodiments, plug seal282and outer cowl286are a single uniform component. Outer cowl286is movable via movement mechanisms287to increase the volume of a mechanically variable throat288. Portions of plug ring285and/or outer cowl286contacting or coming proximate to plug housing284may be coated in a dampening material, as may corresponding portions of plug housing284. The dampening material cushions the impact of contacting portions of these components when decompressive extinguishing plug nozzle280transitions from the active configuration to the decompressive configuration. Additionally or alternatively, this dampening could be accomplished via springs. The volume surrounding plug281and defined by plug281, plug housing284, plug ring285, and outer cowl286provides a mechanically variable throat288. Movement mechanisms287could be electrical, mechanical, hydraulic, electromechanical, magnetic, and/or any other suitable mechanism to facilitate movement without deviating from the scope of the invention. For example, electromagnet(s) could be deenergized to permit outer cowl286to be moved out by the internal combustion pressure. After decompression, decompressive extinguishing plug nozzle280may be returned to the active or sealed configuration by returning outer cowl286to its original position via movement mechanisms287. Computing system290may then initiate another burn at some point. Computing system290may then activate electrolyzer240to produce more hydrogen and oxygen gas and then ignite the hydrogen and oxygen gas by controlling igniter250. The solid rocket motor would then burn yet again. Pressure sensors222(e.g., pressure transducers) are included within combustion chamber220to detect pressure. In certain embodiments, one or more such sensors may be included in decompressive extinguishing plug nozzle280. Using pressure sensors222, software running on computing system290monitors the current pressure during the burn. Should the pressure go too high or deviate significantly from the expected pressure profile, an auto abort command may be initiated to open outer cowl286and decompress combustion chamber220. Decompressive extinguishing plug nozzle280may then be returned to the active or sealed configuration. By having a mechanism like decompressive extinguishing plug nozzle280to rapidly open mechanically variable throat288, an overpressure or runaway pressure event may be alleviated to avoid the rocket blowing up. With reference toFIG.2B, decompressive extinguishing plug nozzle280in this embodiment includes plug281housed within plug housing284. Plug281includes plug seal282that seals plug281from combustion chamber220, with the exception of holes283in plug seal282that allow exhaust to escape combustion chamber220. Decompressive extinguishing plug nozzle280includes plug ring285surrounding an upper part of a flared portion of plug281and outer cowl286that surrounds plug ring285and contacts plug housing284. In some embodiments, plug seal282, plug housing284, and/or cowl286are a single uniform component. Plug281is movable via movement mechanism287to provide a choked flow in the depicted active configuration, and to decompress combustion chamber220in the decompressive configuration. The decompressive configuration increases the volume of mechanically variable throat area288. The volume surrounding plug281and defined by plug281, plug housing284, and plug ring285provides a mechanically variable throat area288. Further details regarding some embodiments of decompressive extinguishing plug nozzle280may be found in U.S. Provisional Patent Application No. 62/879,783. FIG.3is a perspective view illustrating a CubeSat310with a solid rocket motor310capable of multiple burns, according to an embodiment of the present invention. In some embodiments, solid rocket motor310may be solid rocket motor200ofFIG.2A. It should also be noted that instead of a CubeSat, solid rocket motor may be integrated with any desired manned or unmanned terrestrial or space vehicle without deviating from the scope of the invention. Solid rocket motor310includes an outer cowl312and a nozzle314. Solid rocket motor is also movable via a gimbaled actuator320so thrust can be oriented in a range of directions. In some embodiments, at least one solid rocket motor310may be located on a different side of CubeSat300in order to provide thrust in various directions. Any desired number of solid rocket motors may be affixed to one or more sides without deviating from the scope of the invention. The use of solid rocket motors for space vehicles has the advantage of facilitating rapid insertion into the desired orbit(s). For instance, a constellation of CubeSats could be deployed from a dispenser to their respective orbits in a matter of days. Also, space vehicles could be moved to different orbits to avoid other space vehicles or debris fields. Space vehicles could also be deorbited on command, and if large enough that debris will strike the ground after reentry, solid rockets could be used to deorbit the vehicle to a relatively safe and unpopulated location, such as non-shipping lane areas of the Pacific Ocean. FIG.4illustrates an electrolyzer400, according to an embodiment of the present invention. In some embodiments, electrolyzer400may be electrolyzer120ofFIG.1or electrolyzer240ofFIGS.2A and2B. Electrolyzer400includes a water reservoir and an anode420located between a PEM430and water reservoir420. In some embodiments, water reservoir410may be water reservoir230ofFIGS.2A and2B. Alternatively, water may be supplied to water reservoir410by an external water tank, such as water tank110ofFIG.1. A cathode440is located on the side of PEM430opposite anode420. When a direct current (DC) voltage is applied to anode420and cathode440via a power supply unit (PSU)460, water in water reservoir410is oxidized to oxygen and protons (H+). The protons pass through PEM430to cathode440(also known as a hydrogen electrode), and the protons are reduced to hydrogen gas in hydrogen chamber450, obtaining electrons. Oxygen (O2) and hydrogen (H2) are then output from electrolyzer400via oxygen feed line470and hydrogen feed line480, respectively. Electrolyzer400is a single cell electrolyzer. However, multi-cell electrolyzers may also be used. A dual cell electrolyzer500is shown inFIG.5. Dual cell electrolyzer500includes a wet cell510and a dry cell520. Wet cell510and dry cell520are supplied with a voltage from a power source530. Wet cell510includes a PEM electrolyzer512and two water plenums514at opposite ends of electrolyzer512. Water from water plenums514is fed into electrolyzer512, where water is converted to 2e−+2H++½O2on the anode side. On the cathode side, 2e−+2H+is converted to H2. Due to the liquid water in wet cell510, the product H2and O2gases are “wet” in that they become humidified and may possibly contain entrained water droplets. The oxygen from PEM electrolyzer512flows to the anode side of dry cell520via wet oxygen line540, and flow of oxygen is controlled by a valve542. The hydrogen from PEM electrolyzer512flows to the cathode side of dry cell520via wet hydrogen line550, and flow of hydrogen is controlled by a valve552. A PEM electrolyzer522of dry cell520adsorbs the water from the wet H2and O2gas streams and converts the water to additional H2and O2, thus “drying” the product gasses and increasing the H2and O2yield of the water from water reservoir420. Dry oxygen and dry hydrogen is output to dry oxygen feed line560and dry hydrogen feed line570. Flow of gas in dry oxygen feed line560and dry hydrogen feed line570is controlled by valves562,572, respectively. FIGS.6A and6Billustrate a catalytic igniter600, according to an embodiment of the present invention. Catalytic igniter600is fed independently by a gaseous hydrogen feed line610and a gaseous oxygen feed line620. A portion of gaseous hydrogen feed line610and gaseous oxygen feed line620are surrounded by a feed line housing660(seeFIG.6B). This protects a portion of feed lines610,620from exposure to combustion chamber650. Near where feed lines610,620enter a combustion chamber650, they include independent ball bearing (“BB”) style backflow prevention valves630. In BB style backflow prevention valves630, gas can flow freely in one direction (i.e., towards combustion chamber650). However, when the gas flows in the opposite direction, the BB is pushed up against a hole, stopping the flow of gas. Gaseous hydrogen feed line610and gaseous oxygen feed line620then independently extend into combustion chamber650to the point where they are combined coincident with a catalyst bed640(e.g., a catalyst pellet bed that includes ˜10% iridium on alumina) near to the primary propellant (not shown). To ignite the solid rocket motor, the following sequence occurs: (1) igniter600is fed by gaseous hydrogen feed line610and gaseous oxygen feed line620, which receive hydrogen and oxygen, respectively, from an internal source (e.g., storage tanks, an electrolyzer, etc.); (2) the pressure from the feed of gaseous hydrogen and oxygen opens respective backflow valves630; (3) the gases flow independently to catalyst bed540, where they combine on catalyst bed640at stoichiometric proportions; (4) the temperature of catalyst bed640raises to the flash point temperature of a stoichiometric hydrogen and oxygen mixture (e.g., approximately 850° C. on the surface at atmospheric pressure at Los Alamos National Laboratory for an experiment); (5) after the flash ignition event, a sustained flame occurs at the point of hydrogen/oxygen mixing (i.e., at the tip of gaseous hydrogen feed line610and gaseous oxygen feed line620within combustion chamber650; (6) this flame ignites the propellant; and (7) as the chamber pressure rises to become greater than the feed pressure, backflow prevention valves630seal gaseous hydrogen feed line610and gaseous oxygen feed line620from combustion chamber650. It may be beneficial to use a catalyst bed material that is not significantly poisoned by combustion chamber products. Also, the catalyst should survive most realistic combustion chamber pressures and temperatures. Therefore, the system of some embodiments is completely reusable for many burns to many (e.g., dozens or more). Typically, ignition systems for solid rockets are single-use igniters that employ pyrotechnics, hypergolic liquids, or other hazardous materials. However, the ignition systems of some embodiments employ relatively benign materials (e.g., steel, aluminum, aluminum oxide, and iridium). Such materials are suitable for launch rideshare, for example. Whereas liquid fuel rockets have used catalytic igniters, these igniters are complex in their approach to achieving stoichiometric mixture burning of hydrogen and oxygen. The complexity arose from preventing “flashback” and improving the life of the igniter to often extremely long times (e.g., a common approach was to ignite a hydrogen rich mixture and bring the flame products to stoich downstream of the catalyst). However, some embodiments employ a novel and relatively straightforward approach to this problem in that mixing occurs only in the catalyst bed and is stoichiometric at that point. Rather than a catalytic igniter, some embodiments employ a spark igniter. Such a spark igniter700is shown inFIGS.7A and7B. Spark igniter700includes a wire710that can carry a current and cause a spark at the end closest to gaseous hydrogen feed line720and gaseous oxygen feed line730. The spark then ignites the gaseous hydrogen and oxygen, which ignites rocket fuel (not shown). Catalytic or spark igniters of some embodiments, such as those depicted in6A-7B, may be suitable for a variety of rockets. Such igniters may provide a relatively simple, safe, and reusable ignition system. Such embodiments may also improve the safety and environmental friendliness of arming and ignition, which provides a significant advantage. FIGS.8A and8Billustrate an embodiment of a decompressive extinguishing plug nozzle800in an active or sealed configuration. Decompressive extinguishing plug nozzle800is attached to a rocket body880and includes an outer cowl810, a cowl housing812, a plug ring820, and a plug830. In some embodiments, cowl810and cowl housing812are formed as one integral piece. Collectively, plug ring820and plug830provide an aerospike nozzle due to the shape and position of plug830with respect to plug ring820. In a sealed configuration (i.e., when gas is being built up inside a combustion chamber890), plug830and outer cowl810collectively impede the nozzle defined by plug ring820and seal combustion chamber890(seeFIG.8E) since springs866bias decompressive extinguishing plug nozzle800closed. Once sufficient pressure builds in combustion chamber890, the force generated by springs866is overcome by the gas pressure and outer cowl810is pushed slightly away such that plug830no longer completely impedes the nozzle, and rocket exhaust is able to pass around plug830and out through plug ring820via a gap870. The decompressive extinguishing plug nozzle is now in the active configuration and ready for the rocket motor to be ignited. Since plug830and plug ring820are in the flow of the hot exhaust and may be subjected to temperatures of 2,000° C. to 3,000° C. or more, plug830and plug ring820are constructed from a high temperature-compatible material, such as graphite, boron carbide, ceramics, etc. It should be noted that for atmospheric flight where air is available, springs866may not be included and decompressive extinguishing plug nozzle800may lack a sealed configuration. However, where only space flight or both atmospheric and reignited space flight are planned, the sealed configuration may be beneficial. This is because combustion gases are allowed to build in the combustion chamber, which allows the rocket motor to burn for the first time in space, or to burn again in space after being extinguished. Decompressive extinguishing plug nozzle800includes a plug housing840that houses plug830. Plug housing840is connected to plug830via plug seal832. Plug seal832also seals against the inside of rocket body880around its peripheral edges, located downstream from a combustion chamber890(seeFIG.8E). Plug seal832has passages834that allow exhaust to flow around plug830through plug housing840and plug ring820, and then out of the nozzle defined by plug ring820. In some embodiments, in addition to or in lieu of springs866, passages834may be vents that can close to put decompressive extinguishing plug nozzle800in the sealed configuration and open to put decompressive extinguishing plug nozzle800in the active configuration. The volume surrounding plug830and defined by plug830, plug housing840, and outer cowl810provides a mechanically variable throat850. Mechanically variable throat850defines the sonic “choked” flow. In the “activated” configuration in some embodiments, mechanically variable throat850is appropriate to balance the rate of product mass creation from the burning in combustion chamber890with the desired pressure within combustion chamber890needed to achieve a high specific impulse burn. For instance, pressures may be 500 to 2,000 pounds per square inch (psi) or more in some embodiments. Movement mechanisms860(seeFIG.8E) include a plug housing portion862and an outer cowl portion864that hold outer cowl810and a portion of plug ring820against a lip844of plug housing840, as well as next to a plug ring guard816. In some embodiments, movement mechanisms860are controlled by a computing system, such as computing system1500ofFIG.15. In certain embodiments, accelerometers, such as accelerometer(s)1545of computing system1500, are included in one or more locations on the rocket to determine acceleration characteristics. Movement mechanisms860could be electrical, mechanical, hydraulic, electromechanical, magnetic, and/or any other suitable mechanism to facilitate movement without deviating from the scope of the invention. For example, the polarity of the electromagnet(s) could be reversed to drive them apart and permit outer cowl810to be moved out by a combination of this force and the internal combustion pressure. Keeping the electromagnet(s) reversed after the rocket motor is extinguished may overcome the force of springs866to keep the decompressive configuration maintained. However, where no sealed configuration is needed, or it is desired for decompressive extinguishing plug nozzle800to return to the sealed configuration immediately after the rocket motor is extinguished, the electromagnet(s) could simply be deenergized. This movement forced by the combustion pressure is a novel aspect of some embodiments. After extinguishing the fuel, the polarity of the electromagnet(s) could then be reversed to draw outer cowl and plug housing840together, returning decompressive extinguishing plug nozzle800to the active configuration or sealed configuration. In some embodiments, springs866may have sufficient strength to seal decompressive extinguishing plug nozzle. It should be noted that any desired number and/or types of movement mechanisms may be used without deviating from the scope of the invention. FIGS.8C and8Dillustrate decompressive extinguishing plug nozzle800in a decompressive configuration. To transition from the active configuration to the decompressive configuration, movement mechanisms860create separation between outer cowl810/cowl housing812and plug housing840, as denoted by the gray arrows inFIG.8D. This separation could be created by deenergizing electromagnets, activating actuators, extending rods via hydraulic mechanisms, any combination thereof, etc. When in the decompressive configuration due to a rapid separation between outer cowl810/cowl housing812and plug housing840, a sudden drop in pressure occurs in mechanically variable throat850. In some embodiments, the decompression rates may be 50 kilopounds per square inch (ksi) per second or greater. This rapid decompression occurs in combustion chamber890as well via passages834and extinguishes the rocket motor. It should be noted that in some embodiments, lip844moves vertically past extension816, forming a gap that exposes outside air or space to the interior of plug housing840. This may drop the pressure even further, facilitating more rapid extinguishing of the rocket motor. FIG.8Eis a side cutaway view illustrating the bottom portion of a rocket with decompressive extinguishing plug nozzle810, according to an embodiment of the present invention. Combustion chamber890is surrounded by fuel892and an oxidizer994that provides oxygen so fuel892can combust fully at all altitudes. However, it should be noted that more traditional composite monopropellants, such as ammonium perchlorate, may be used. Indeed, the decompressive concept will work for any solid rocket fuel in some embodiments. Pressure sensors896(e.g., pressure transducers) are included within combustion chamber890to detect pressure. In certain embodiments, one or more such sensors may be included in decompressive extinguishing plug nozzle800. Using pressure sensors896, software running on a computing system (e.g., computing system1500ofFIG.15) monitors the current pressure during the burn. Should the pressure go too high or deviate significantly from the expected pressure profile, an auto abort command may be initiated to open outer cowl810and decompress combustion chamber890. Decompressive extinguishing plug nozzle800may then be returned to the active or sealed configuration. By having a mechanism like decompressive extinguishing plug nozzle800to rapidly open mechanically variable throat850, an overpressure or runaway pressure event may be alleviated to avoid the rocket blowing up. Lip814of cowl housing812contacts the outside of rocket body880. Plug housing840is sealed against the end and inside of rocket body880. Plug seal832also seals against the inside of rocket body880. As such, in this embodiment, it is outer cowl810/cowl housing812, and by extension, plug ring820, that are movable via movement mechanism860. FIG.9illustrates some example plug designs, according to an embodiment of the present invention. Plugs900,910,920,930may be substituted for plug830ofFIGS.1A-Ein some embodiments. However, any suitable plug shape may be used without deviating from the scope of the invention. In some embodiments, such as nozzle system940, the rocket may have a bell-shaped nozzle with a decompressive extinguishing plug nozzle. Any rocket nozzle and plug type is contemplated within the scope of the present invention, so long as the fuel can be extinguished via rapid decompression. In some embodiments, the plug may be movable instead of the outer cowl. In such embodiments, a feature on a wall side may be included to set the mechanically variable throat area. A plug behind a cowl inside the vehicle may be moved in or a plug outside the vehicle after an aperture (i.e., a nozzle) may be moved out. If similar to nozzle system940ofFIG.9, for example, moving the plug itself may make more sense to facilitate decompression. FIG.10Ais a side cutaway view illustrating a decompressive extinguishing plug nozzle1000in an active configuration, according to an embodiment of the present invention. It should be noted that in some embodiments, decompressive extinguishing plug nozzle1000incorporates one, some, or all of the features fromFIGS.8A-Ethat are unlabeled and/or non-illustrated inFIGS.10A and10B. In certain embodiments, decompressive extinguishing plug nozzle1000is also configured to have a sealed configuration so gas pressure can build in the combustion chamber prior to ignition. As with decompressive extinguishing plug nozzle800ofFIGS.8A-E, decompressive extinguishing plug nozzle1000includes a cowl1010, a cowl housing1012, a plug ring1020, a plug1030, a plug housing1040, and a mechanically variable throat1060. However, in this embodiment, rather than being attached to a plug seal, plug1030is attached to a rod1052of a seal1050that extends through plug1030. The mechanism for moving decompressive extinguishing plug nozzle1000is not shown herein. However, any suitable mechanism may be used without deviating from the scope of the invention. In this embodiment, rod1052was included for structural reasons. If plug1030is made from a solid piece of graphite, for example, the graphite is quite brittle. Vibrations in decompressive extinguishing plug nozzle1000may cause failure in the neck of plug1030near seal1050. Accordingly, including a rod1052that is designed for flexibility and robustness under vibration (e.g., steel, aluminum, etc.) alleviates this problem. Such a feature may work for plugs of any size and/or type, including for static nozzles. Decompressive extinguishing plug nozzle1000can also be moved into a decompressive configuration, as shown inFIG.11B. In the decompressive configuration, plug1030and rod1052remain fixed in this embodiment while cowl1010/cowl housing1012move. This increases the area of mechanically variable throat1060and causes rapid decompression, extinguishing the burning solid rocket fuel in the combustion chamber. In some embodiments, passages1042to vent out transverse to the direction of travel and/or passages1016in lip1014may be provided. Additionally or alternatively, in certain embodiments, passages1018may be included in cowl1010to ensure that gasses that are unintentionally vented into the volume between cowl1010and plug housing1040can easily leave. It should be noted that such passages may also be included in decompressive extinguishing plug nozzle800ofFIGS.8A-E, for example. FIGS.11A-Fillustrate a decompressive extinguishing plug nozzle1100, according to an embodiment of the present invention. Decompressive extinguishing plug nozzle utilizes wheel bearings1110(e.g., wheels) sitting on shelves1122that are formed in a cowl housing1120. Any desired number, size, shape, and/or location of wheels and shelves may be used without deviating from the scope of the invention. Shelves1122define tracks along which wheel bearings1110may roll along the edges of respective shelves1122. In this embodiment, wheel bearings1110are attached to a rocket body1130. Rocket body1130also defines a combustion chamber1132within. A portion of cowl housing1120surrounds rocket body1130. The remaining components of extinguishing plug nozzle1100that are in this embodiment are housed within cowl housing1120are the same as those shown inFIGS.11A and11B. However, any suitable extinguishing plug nozzle design may be housed therein without deviating from the scope of the invention. InFIGS.11A,11C, and11E, decompressive extinguishing plug nozzle1100is in the active configuration. In some embodiments, decompressive extinguishing plug nozzle1100is also configured to have a sealed configuration so gas pressure can build in the combustion chamber prior to ignition. When in the active configuration, shelves1122translate the large force along the motor thrust axis to wheel bearings1110in the form of a relatively small torque for ease of retention. Some embodiments, such as that depicted inFIGS.11A-F, may be made with very low mass, which is beneficial for space applications. This is a novel aspect of some embodiments. To move to the decompressive configuration, as shown inFIGS.11B,11D, and11F, a solenoid (not shown) may be used to cause cowl housing1120and wheel bearings1110to rotate. Alternatively, shelves1122may have an incline such that when a pin (not shown) is pulled, the pressure from the burning fuel naturally drives the rotation and decompression. Such embodiments may be made resettable via a spring, via a spring and another pin holding the decompressive extinguishing plug nozzle in the decompressive position until a command is received, and/or via a solenoid, for example.FIGS.12A and12Bshow a decompressive extinguishing plug nozzle1200in an active and decompressive configuration, respectively, according to an embodiment of the present invention. In some embodiments, decompressive extinguishing plug nozzle1200is also configured to have a sealed configuration so gas pressure can build in the combustion chamber prior to ignition. As with decompressive extinguishing plug nozzle1100ofFIGS.11A-F, decompressive extinguishing plug nozzle1200utilizes wheel bearings1210sitting on shelves1222that define tracks and are formed in a cowl housing1220. Only one wheel bearing1210and shelf1220are visible in this embodiment. However, in certain embodiments, only a single wheel bearing and track may be used. Indeed, any desired number, size, shape, and/or location of wheels and shelves may be used without deviating from the scope of the invention. Shelves1222define tracks along which wheel bearings1210may roll along the edges of respective shelves1222. However, in this embodiment, a solenoid1240is attached to a rocket body1230. Solenoid1240has a pin1242that engages with pin locks1224,1226of cowl housing1220. With reference toFIG.12A, when pin1242is pulled from pin lock1224by solenoid1240, the combustion chamber pressure generates a torque, causing wheel bearings1210to rotate along shelves1222. Cowl housing1220moves both upward and rotates to the left fromFIG.12AtoFIG.12Bwith respect to the orientations shown therein. Pin1242then engages with and locks into pin lock1226. In certain embodiments, springs (not shown) may bias cowl housing1220in a downward direction with respect toFIGS.12A and12B. The springs do not have sufficient strength to overcome the combustion chamber pressure and keep cowl housing1220in place when pin1242is released in the active configuration. However, once the rocket motor is extinguished, when pin1242is released from pin lock1226in the decompressive configuration, cowl1220can return to the active configuration setting by moving in the opposite directions as those shown inFIG.12B, returning to the active configuration ofFIG.12A, or to a sealed configuration. It should be noted that the wheel and rotating cowl concept ofFIGS.11A-12Bmay be a very scalable mechanism. If the rocket is large, more wheels may be spaced around the cowl. For instance, very large rockets may have many relatively small wheels (e.g., dozens, hundreds, etc.) in some embodiments. Indeed, any desired wheel size, location, track shape, and/or number of wheels/tracks may be used without deviating from the scope of the invention. Such embodiments may be more scalable than those that use pipes containing liquids (e.g., hydraulics), pumps, etc. FIG.13is a flowchart illustrating a process1300for facilitating multiple burns with a solid rocket motor, according to an embodiment of the present invention. The process begins with igniting the rocket motor at1310. For each firing, hydrogen and oxygen are provided to an igniter. The hydrogen and oxygen may be supplied from benign water decomposed on demand into gaseous hydrogen and oxygen by an electrolyzer. The gaseous hydrogen and oxygen may be recombined on a catalyst bed igniter within the combustion chamber to cause high temperatures. Additionally or alternatively, a spark igniter may be used to ignite the hydrogen and oxygen. The igniter should survive the temperatures and pressures of multiple burns and be reusable in some embodiments. The ignited hydrogen and oxygen then ignite solid fuel, which then burns. In some embodiments, a segmented solid fuel solid oxidizer system or any desired composite monopropellant may then be used. However, the specific fuel and/or oxidizer that is used is not critical in some embodiments, so long as it is capable of combustion and propelling the rocket. The rocket motor then burns until the desired stopping criteria are reached at1320. These may include, but are not limited to, a desired total impulse, a desired total change in velocity, and/or any other desired criteria related to the burn without deviating from the scope of the invention. The criteria may be determined from output by one or more accelerometers, for example. Once the desired criteria are achieved for the current burn (e.g., as detected by a computing system analyzing measurements from accelerometer(s)), a nozzle with a mechanically variable throat area affects rapid decompression of the combustion chamber at1330, resulting in extinguishing of the burn. The nozzle is then reset to an active or sealed configuration at1340, and the rocket motor may be reignited when desired by returning to step1310and repeating the process. FIG.14is a flowchart illustrating a process1400for extinguishing a solid rocket motor using a decompressive extinguishing plug nozzle, according to an embodiment of the present invention. The process optionally begins with moving the outer cowl against the plug housing to arm the rocket at1410. In certain embodiments, flying a system in the decompressive configuration for added safety against an accidental impulsive firing may be beneficial. The general concept would be to arm the system by pulling in the cowl to the active or sealed configuration prior to firing the rocket. Such a nozzle may be used just for this safety/arming purpose regardless of extinguishing in certain embodiments. Then, the rocket motor is ignited at1420(which may be the first step in some embodiments per the above). The rocket motor is commanded to fire for a specified time or until a specified impulse is reached at1430. Computing system1500, for example, may be used to determine the total velocity change via accelerometers (e.g., accelerometer(s)1545). After a desired burn time, an outer cowl of a decompressive extinguishing plug nozzle is moved away from a plug housing at1540. This causes rapid decompression of the combustion chamber, extinguishing the fuel. In some embodiments, only a single burn and decompression may be desired. However, in other embodiments, the outer cowl is moved back against the plug housing at650, resetting the decompressive extinguishing plug nozzle to an active or sealed configuration where the rocket motor can be fired again. The process may then proceed to step620and be repeated as many times as desired. FIG.15is a block diagram illustrating a computing system1500configured to control a solid rocket motor and/or a decompressive extinguishing plug nozzle, according to an embodiment of the present invention. Computing system1500may be a flight computer, for example. Computing system1500includes a bus1505or other communication mechanism for communicating information, and processor(s)1510coupled to bus1505for processing information. Processor(s)1510may be any type of general or specific purpose processor, and may be or be a part of a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a system on a chip (SoC), etc. Processor(s)1510may also have multiple processing cores, and at least some of the cores may be configured to perform specific functions. Multi-parallel processing may be used in some embodiments. Computing system1500further includes a memory1515for storing information and instructions to be executed by processor(s)1510. Memory1515can be comprised of any combination of random access memory (RAM), read only memory (ROM), flash memory, cache, static storage such as a magnetic or optical disk, or any other types of non-transitory computer-readable media or combinations thereof. Additionally, computing system1500includes a communication device1520, such as a transceiver and antenna, to wirelessly provide access to a communications network. Non-transitory computer-readable media may be any available media that can be accessed by processor(s)1510and may include volatile media, non-volatile media, or both. The media may also be removable, non-removable, or both. Batteries1540provide power to computing system1500, and potentially to other systems as well. Memory1515stores software modules that provide functionality when executed by processor(s)1510. The modules include an operating system1525for computing system1500. The modules further include a rocket motor and decompression control module1530that is configured to control a solid rocket system and/or a decompressive extinguishing plug nozzle thereof. Computing system1500may include one or more additional functional modules1535that include additional functionality. Batteries1540provide power to computing system1500, and potentially to other systems as well. It may be beneficial to track rocket performance using various sensors. Accordingly, computing system1500includes accelerometer(s)1545for tracking rocket accelerations, pressure sensor(s)1550for tracking pressure within the combustion chamber, for example, and other sensors and/or controls1555(e.g., cameras, actuators controlling flight control surfaces, etc.) that may allow the rocket to monitor its performance and control flight. One skilled in the art will appreciate that a “system” could be embodied as a flight control computer, an embedded computing system, or any other suitable computing device, or combination of devices. Presenting the above-described functions as being performed by a “system” is not intended to limit the scope of the present invention in any way, but is intended to provide one example of many embodiments of the present invention. Indeed, methods, systems and apparatuses disclosed herein may be implemented in localized and distributed forms consistent with computing technology, including cloud computing systems. It should be noted that some of the system features described in this specification have been presented as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom very large scale integration (VLSI) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, graphics processing units, or the like. A module may also be at least partially implemented in software for execution by various types of processors. An identified unit of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions that may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module. Further, modules may be stored on a computer-readable medium, which may be, for instance, a hard disk drive, flash device, RAM, tape, or any other such medium used to store data. Indeed, a module of executable code could be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network. The process steps performed inFIGS.13and14may be controlled by a computer program, encoding instructions for the processor(s) to facilitate at least the process(es) described inFIGS.13and14, in accordance with embodiments of the present invention. The computer program may be embodied on a non-transitory computer-readable medium. The computer-readable medium may be, but is not limited to, a hard disk drive, a flash device, RAM, a tape, or any other such medium used to store data. The computer program may include encoded instructions for controlling the processor(s) to implement the process(es) described inFIGS.13and14. The computer program can be implemented in hardware, software, or a hybrid implementation. The computer program can be composed of modules that are in operative communication with one another. The computer program can be configured to operate on a general purpose computer, an ASIC, or any other suitable device. It will be readily understood that the components of various embodiments of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the detailed description of the embodiments of the present invention, as represented in the attached figures, is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. The features, structures, or characteristics of the invention described throughout this specification may be combined in any suitable manner in one or more embodiments. For example, reference throughout this specification to “certain embodiments,” “some embodiments,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in certain embodiments,” “in some embodiment,” “in other embodiments,” or similar language throughout this specification do not necessarily all refer to the same group of embodiments and the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. It should be noted that reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present invention should be or are in any single embodiment of the invention. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, discussion of the features and advantages, and similar language, throughout this specification may, but do not necessarily, refer to the same embodiment. Furthermore, the described features, advantages, and characteristics of the invention may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the invention can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the invention. One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention. In order to determine the metes and bounds of the invention, therefore, reference should be made to the appended claims. In an embodiment, a multiple burn rocket system includes a hydrogen gas source and an oxygen gas source that provide gaseous hydrogen and oxygen, respectively. The system also includes a combustion chamber that is provided with the hydrogen gas and the oxygen gas and an igniter configured to ignite the hydrogen gas and the oxygen gas. The igniter is located at least partially in the combustion chamber. The system further includes fuel located within the combustion chamber that is ignited by the igniter. Additionally, the system includes a decompressive nozzle that is configured to allow the fuel to burn in an active configuration and to extinguish the fuel in a decompressive configuration. In some embodiments, the system is configured to reignite the fuel after the fuel is extinguished. In certain embodiments, the decompressive nozzle is a decompressive extinguishing plug nozzle. In some embodiments the system further includes an electrolyzer that has access to a water source. The electrolyzer is configured to produce hydrogen gas and oxygen gas via electrolysis. In certain embodiments, the electrolyzer is a PEM electrolyzer that separates hydrogen and oxygen from the water via the PEM. The electrolyzer may include anode and cathode electrodes that are supplied with current from a power source. In some embodiments, the electrolyzer is a single cell electrolyzer. In certain embodiments, the electrolyzer is a multi-cell electrolyzer that includes at least one wet cell and at least one dry cell. In some embodiments, the igniter is a catalytic igniter that includes a catalysts bed where the hydrogen gas and the oxygen gas are recombined, producing heat and igniting the fuel. In certain embodiments, the catalyst bed includes alumina and iridium, or a precious metal catalyst. In some embodiments, the igniter is a spark igniter that is configured to directly ignite the hydrogen gas and the oxygen gas. In certain embodiments, the igniter is constructed from a steel alloy and/or a metalized ceramic. In some embodiments, the system includes an oxidizer that facilitates more efficient combustion of the fuel. In certain embodiments the system includes a computing system and an accelerometer. The computing system is configured to control the operation of the system, and to extinguish and/or reignite the fuel based on input form the accelerometer. In another embodiment, a multiple burn rocket system includes a water source and a PEM electrolyzer operably connected to the water source. The PEM electrolyzer is configured to create hydrogen gas and oxygen gas from the water source. The system also includes a combustion chamber that is provided with the hydrogen gas and the oxygen gas produced by the electrolyzer and an igniter configured to ignite the hydrogen gas and the oxygen gas. The igniter is located at least partially in the combustion chamber. The system further includes fuel located within the combustion chamber that is ignited by the igniter. Additionally, the system includes a decompressive nozzle that is configured to allow the fuel to burn in an active configuration and to extinguish the fuel in a decompressive configuration. In yet another embodiment, a multiple burn rocket system includes a water source and a PEM electrolyzer operably connected to the water source. The PEM electrolyzer is configured to create hydrogen gas and oxygen gas from the water source. The system also includes a combustion chamber that is provided with the hydrogen gas and the oxygen gas produced by the electrolyzer. The system further includes a catalytic igniter or a spark igniter configured to ignite the hydrogen gas and the oxygen gas. The igniter is located at least partially in the combustion chamber. Additionally, the system includes fuel located within the combustion chamber that is ignited by the igniter and an oxidizer that facilitates more efficient combustion of the fuel. Additionally, the system includes a decompressive extinguishing plug nozzle that is configured to allow the fuel to burn in an active configuration and to extinguish the fuel in a decompressive configuration. In still another embodiment, a method includes igniting a rocket motor using an igniter and a supply of hydrogen gas and oxygen gas and allowing the rocket motor to burn until a desired impulse is reached. After the desired impulse is reached, the method also includes decompressing a combustion chamber of the rocket motor via a decompressive nozzle, thereby extinguishing the rocket motor. In some embodiments, the method further includes resetting the decompressive nozzle to an active configuration, or to a sealed configuration followed by an active configuration, and reigniting the rocket motor. In certain embodiments, the process may be repeated an arbitrary number of times based on fuel constraints. In an embodiment, a solid fuel rocket includes a decompressive extinguishing plug nozzle having a variable mechanical throat defining a choked sonic flow when the decompressive extinguishing plug nozzle is in an active configuration, a combustion chamber, and a computing system configured to control operation of the solid fuel rocket. The computing system is configured to control the decompressive extinguishing plug nozzle to transition from an active configuration that allows solid rocket fuel in the combustion chamber to burn to a decompressive configuration where the solid rocket fuel is extinguished by increasing an area of the variable mechanical throat of the decompressive extinguishing plug nozzle. In certain embodiments, the decompressive extinguishing plug nozzle is configured to transition from a sealed configuration to an active configuration to a decompressive configuration, and then back to the sealed configuration. In some embodiments, the decompressive extinguishing plug nozzle is attached to a body of the solid fuel rocket. In certain embodiments, the decompressive extinguishing plug nozzle includes an outer cowl, a cowl housing, and a plug. In certain embodiments, the decompressive extinguishing plug nozzle further includes a plug ring defining a nozzle and located within the outer cowl. In some embodiments, the plug ring and the plug provide an aerospike nozzle due to a shape and position of the plug with respect to the plug ring such that the plug does not completely impede the nozzle defined by the plug ring, and rocket exhaust is able to pass around the plug and out through the plug ring via a gap therebetween. In some embodiments, the decompressive extinguishing plug nozzle includes a plug housing that houses the plug, the plug housing connected to the plug via a plug seal. The plug seal seals against an inside of a body of the solid fuel rocket around its peripheral edges, located downstream from the combustion chamber. In certain embodiments, the plug seal includes passages that allow exhaust to flow around the plug through the plug housing and the plug ring, and then out of the nozzle defined by the plug ring. In some embodiments, the decompressive extinguishing plug nozzle includes springs that bias the decompressive extinguishing plug nozzle into a sealed configuration when there is insufficient gas pressure in the combustion chamber to move the decompressive extinguishing plug nozzle into an active configuration. In certain embodiments, in addition to or in lieu of springs, decompressive extinguishing plug nozzle includes vents configured to close to put the decompressive extinguishing plug nozzle in the sealed configuration and open to put the decompressive extinguishing plug nozzle in the active configuration. In some embodiments, a volume surrounding the plug and defined by the plug, the plug housing, and the outer cowl provides the mechanically variable throat. In certain embodiments, one or more movement mechanisms facilitate movement between the active configuration and the decompressive configuration by moving the outer cowl so as to increase an area of the mechanically variable throat, or by allowing the outer cowl to be moved by a combustion chamber pressure. In certain embodiments, the solid fuel rocket includes one or more accelerometers that provide acceleration information to the computing system. In some embodiments, the solid fuel rocket includes one or more pressure sensors that provide pressure information in the combustion chamber, the decompressive extinguishing plug nozzle, or both, to the computing system. In certain embodiments, the computing system is configured to cause the decompressive extinguishing plug nozzle to transition from the active configuration to the decompressive configuration when data from the one or more pressure sensors indicates that the pressure is above a threshold value and/or has deviated beyond a tolerance from an expected pressure profile. In some embodiments, the plug housing of the decompressive extinguishing plug nozzle includes a first lip and the outer cowl or a cowl housing includes a second lip. The first lip and the second lip are configured to limit a range of motion of the outer cowl when the decompressive extinguishing plug nozzle transitions from the active configuration to the decompressive configuration. In certain embodiments, the plug is operably connected to a rod that is operably connected to the plug seal. The rod may be more flexible and less brittle than the plug. In some embodiments, passages may be provided in the plug housing to vent out transverse to the direction of travel, passages may be provided in the lip to vent therefrom, and/or passages may be included in the outer cowl to ensure that gasses that are unintentionally vented into the volume between the outer cowl and the plug housing can leave the decompressive extinguishing plug nozzle. In some embodiments, the decompressive extinguishing plug nozzle includes one or more wheel bearings sitting on one or more respective shelves that are formed in the cowl housing. The one or more shelves define tracks along which respective wheel bearings roll along the edges of respective shelves. In certain embodiments, the one or more wheel bearings are attached to a body of the solid fuel rocket. In some embodiments, a portion of the cowl housing surrounds the rocket body. In some embodiments, a solenoid is attached to the body of the solid fuel rocket. In certain embodiments, the solenoid has a pin that engages with pin locks of the cowl housing and facilitates rotation of the cowl housing and the transition between the active configuration and the decompressive configuration. In another embodiment, a method for controlling a decompressive extinguishing plug nozzle includes moving an outer cowl against a plug housing into a sealed configuration or an active configuration to arm a solid fuel rocket. The method also includes igniting a rocket motor of the solid fuel rocket and commanding the rocket motor to fire for a specified time or until a specified impulse is reached. Once the specified time elapses or the specified impulse is reached, the method further includes moving the outer cowl away from the plug housing and into a decompressive configuration, causing the rocket motor to be extinguished. In some embodiments, the process of firing and extinguishing the rocket motor is then repeated. In certain embodiments, if a pressure is detected in the combustion chamber, the extinguishing plug nozzle, or both, the method includes moving the outer cowl away from the plug housing and into a decompressive configuration, causing the rocket motor to be extinguished. In yet another embodiment, a decompressive extinguishing plug nozzle includes an outer cowl, a cowl housing, a plug, a plug housing, and a plug seal. The plug housing houses the plug and is connected to the plug via a plug seal. The plug seal seals against an inside of a body of the solid fuel rocket around its peripheral edges, located downstream from the combustion chamber. A volume surrounding the plug and defined by the plug, the plug housing, and the outer cowl provides the mechanically variable throat. In certain embodiments, the plug seal includes passages that allow exhaust to flow around the plug through the plug housing and the plug ring, and then out of the nozzle defined by the plug ring. In some embodiments, the decompressive extinguishing plug nozzle also includes a plug ring defining a nozzle and located within the outer cowl. In certain embodiments, the plug ring and the plug provide an aerospike nozzle due to a shape and position of the plug with respect to the plug ring such that the plug does not completely impede the nozzle defined by the plug ring, and rocket exhaust is able to pass around the plug and out through the plug ring via a gap therebetween. In some embodiments, the plug housing of the decompressive extinguishing plug nozzle includes a first lip and the outer cowl or a cowl housing includes a second lip. The first lip and the second lip are configured to limit a range of motion of the outer cowl when the decompressive extinguishing plug nozzle transitions from an active configuration to a decompressive configuration. In certain embodiments, the plug is operably connected to a rod that is operably connected to the plug seal. The rod may be more flexible and less brittle than the plug. In some embodiments, passages may be provided in the plug housing to vent out transverse to the direction of travel, passages may be provided in the lip to vent therefrom, and/or passages may be included in the outer cowl to ensure that gasses that are unintentionally vented into the volume between the outer cowl and the plug housing can leave the decompressive extinguishing plug nozzle. In still another embodiment, a decompressive extinguishing plug nozzle includes a cowl housing that includes one or more respective shelves formed in the cowl housing. The one or more shelves define tracks along which respective wheel bearings of a rocket body roll along the edges of respective shelves. In some embodiments, a portion of the cowl housing surrounds the rocket body. The tracks facilitate movement of the cowl housing between an active state and a decompressive state of the decompressive extinguishing plug nozzle (and in some embodiments, vice versa). In some embodiments, the cowl housing includes pin locks for each of the active configuration and the decompressive configuration. A solenoid is attached to the body of the solid fuel rocket may include a pin that engages with the pin locks of the cowl housing and facilitates rotation of the cowl housing and the transition between the active configuration and the decompressive configuration. | 70,148 |
11859580 | It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the present disclosure. The specific design features of the present disclosure as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. In the figures, reference numbers refer to the same or equivalent parts of the present disclosure throughout the several figures of the drawing. DETAILED DESCRIPTION Hereinafter, embodiments of the present disclosure are described in detail with reference to the accompanying drawings. Specific structures or functions described in the embodiments of the present disclosure are merely for illustrative purposes. Embodiments according to the concept of the present disclosure may be implemented in various forms. It should be understood that the structures and functions of the present disclosure should not be construed as being limited to the embodiments described in the present specification, but include all of modifications, equivalents, or substitutes included in the spirit and scope of the present disclosure. It should be understood that, although the terms “first,” “second,” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For instance, a first element discussed below could be termed a second element without departing from the teachings of the present disclosure. Similarly, the second element could also be termed the first element. When a component, device, element, or the like of the present disclosure is described as having a purpose or performing an operation, function, or the like, the component, device, or element, should be considered herein as being “configured to” meet that purpose or to perform that operation or function. It should be understood that when an element is referred to as being “coupled” or “connected” to another element, it can be directly coupled or connected to the other element or intervening elements may be present therebetween. In contrast, it should be understood that when an element is referred to as being “directly coupled” or “directly connected” to another element, there are no intervening elements present. Other expressions that explain the relationship between elements, such as “between,” “directly between,” “adjacent to,” or “directly adjacent to,” should be construed in the same way. Like reference numerals denote like components throughout the specification. In the meantime, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should be further understood that the terms “comprise,” “include,” “have,” etc., when used in this specification, specify the presence of stated components, steps, operations, and/or elements, but do not preclude the presence or addition of one or more other components, steps, operations, and/or elements thereof. Hereinafter, the present disclosure is described in detail with reference to the accompanying drawings. A general operation example of a device1for supplying injection water according to the present disclosure is illustrated inFIG.2. As described above, compressed air supercharged through a supercharger3is cooled by an intercooler7. The compressed air passing through the intercooler7proceeds to a combustion chamber of an engine5along an air supply line9. Apart from fuel F supplied to the combustion chamber of the engine5, a water injector11for injecting water toward an intake port of the engine5is provided adjacent to the intake port, and cools compressed air flowing toward the engine5. The water supplied to the water injector11is supplied from the device1for supplying injection water through an injection water supply line13. As illustrated inFIG.3, the device1for supplying injection water according to an embodiment of the present disclosure includes a storage unit20, a transport unit40, and a management unit60. The storage unit20stores water to be supplied toward the intake port of the engine5, and the transport unit40functions to send the water stored in the storage unit20up to the intake port of the engine5. The management unit60serves to manage the injection water stored in the storage unit20. The storage unit20is configured to store water. The storage unit20includes a primary input port22. The storage unit20may be filled with the injection water through the primary input port22. In addition, a secondary input port24for receiving the injection water from the outside is provided to the storage unit20. The secondary input port24is be described below. The transport unit40may be connected to the storage unit20and be disposed at an upper portion of the storage unit20. The transport unit40is configured to send out the water in the storage unit20toward the water injector11such that the water is injected from the vicinity of the intake port of the engine5. To this end, according to an embodiment of the present disclosure, the transport unit40includes a motor section42and a pump section44. As illustrated inFIGS.4and5, the motor section42is supplied with power from the outside and provides a rotational force to a pump144. According to an embodiment of the present disclosure, the motor section42includes a motor housing142, a motor242, and a sealing cap342. The motor242is supplied with electric energy from a power supply and operates a stator1242and a rotor2242. The stator1242is installed inside the motor housing142, and the rotor2242is rotatably disposed inside the stator1242. A shaft3242coupled to the rotor2242transfers power of the motor242to the pump144. As a non-limiting example, the motor242may be a brushless direct current (BLDC) motor. The transport unit40may be provided with a motor controller50. The motor controller50is configured to control an operation of the motor242. The motor controller50is configured to control the motor242. The motor controller50receives pressure information from an integrated controller100that controls the device for supplying injection water in an integrated way and implements feedback controls of a rotational speed of the pump144under control of the motor242. According to an embodiment of the present disclosure, the motor controller50may be a printed circuit board. According to the present disclosure, the motor controller50for the control of the pump144is formed integrally with the device1for supplying injection water or the transport unit40, and thereby costs can be reduced. According to some embodiments of the present disclosure, the motor controller50is integrated with the integrated controller100. According to another embodiment of the present disclosure, the motor controller50and the integrated controller100may be formed separately. According to the present disclosure, the motor controller is integrally formed with the device1for supplying injection water, and thereby costs can be reduced. The sealing cap342is mounted on the motor housing142in a water tight manner to protect the motor242from the pump144. According to an embodiment of the present disclosure, the sealing cap342has a plurality of through-holes1342separated at certain intervals in a circumference of the sealing cap342. Couplers1142capable of overlapping the plurality of through-holes1342are provided to the motor housing142or in a circumference of the motor housing142. Fastening members80, such as bolts, may be mounted through the through-holes1342and the couplers1142to couple the motor housing142and the sealing cap342. In this way, the device1for supplying injection water according to the present disclosure has a waterproof structure of the motor section42, thereby improving corrosion resistance. The motor housing142may include a mounting bracket2142for mounting the transport unit40to the storage unit20. Referring toFIG.6, a motor-side cap442is coupled on one side of the motor section42. The motor-side cap442may emit heat of the motor controller50disposed therein. For example, the motor-side cap442may be formed of a material having excellent heat radiation performance, and as a non-limiting example, aluminum may be utilized. Further, a vent1442, which provides fluid communication between the inside and outside of the motor-side cap442, is provided to the motor-side cap442. The vent1442functions to prevent dew condensation in the motor controller50and maintain a pressure of the motor controller50. The pump section44is located on the other side of the motor section42which is a side opposite to the one side of the motor section42. The pump section44is coupled to the motor section42. The pump section44includes the pump144and a pump housing244. The pump144is operably coupled to the motor242or a shaft3242, forms a pressure of the injection water, draws the injection water from the storage unit20, and causes the drawn injection water to flow in a set direction. The pump housing244houses the pump144. The pump housing244is housed in a pump-side cap46coupled to the pump section44. According to an embodiment of the present disclosure, the pump144may be an inline pump. The present disclosure can prevent problems, such as damage when water is frozen in the winter season due to an inline pump system. According to an embodiment of the present disclosure, the pump-side cap46includes a suction port146, a discharge port246, and a bypass port346. The suction port146is configured such that the injection water drawn from the storage unit20flows thereinto. The discharge port246is configured to supply the injection water from the suction port146toward the engine5along the injection water supply line13. The bypass port346functions to return the injection water inside the injection water supply line13to the storage unit20. The bypass port346may be connected to, especially, the secondary input port24of the storage unit20and return the injection water remaining in the injection water supply line13to the storage unit20through the secondary input port24. According to an embodiment of the present disclosure, the motor controller50is configured to enable reverse rotation of the motor242. Therefore, a negative pressure may be formed by the reverse rotation of the motor242, and the water remaining in the injection water supply line13may be directed back to the storage unit20. It is possible to prevent damage to the pump and the line caused by volume expansion when water is frozen at a low temperature, for instance, in the winter season. Therefore, according to the present disclosure, stability and reliability of wintertime supply can be ensured. Further, the present disclosure enables smooth water circulation while enabling simplification by integrating a multifunction discharge structure into the pump-side cap46provided at a lower end of the pump144. The multifunction discharge structure includes the suction port147for directly connecting the storage unit20with the suction port of the pump44, the discharge port246for sending water therefrom to the manifold or the water injector11, and the bypass port346. A pressure sensor446is mounted on the pump-side cap46. The pressure sensor446is configured to detect a pressure inside the pump housing244or the discharge port246. The pressure measured by the pressure sensor446may be transferred to the integrated controller100that manages the device for supplying injection water. The integrated controller100may transmit pressure information to the motor controller50in real time and the motor controller50may have feedback control over the rotational speed of the pump144on the basis of the real-time pressure information. As illustrated inFIGS.7A and7B, a packing member48may be disposed adjacent to an outlet of the pump144. The packing member48has a sealing function that prevents water flowing through the pump144from leaking around the discharge port246, as well as absorbs vibrations caused by operations of the motor242and the pump144. In other words, according to an embodiment of the present disclosure, referring toFIG.6again, the motor controller50is coupled to the motor housing142. The motor controller50placed on the motor section42at the opposite side of the pump section44is covered and protected by the motor-side cap442. The vent1442provided in the motor-side cap442may prevent the dew condensation in the motor controller50and maintain a pressure inside the motor-side cap442. The management unit60is configured to manage the injection water in the storage unit20. More specifically, the management unit60is configured to remove impurities for the injection water in the storage unit20, to control a temperature of the injection water, and to detect a level of the injection water in the storage unit20. As illustrated inFIG.8, according to an embodiment of the present disclosure, the management unit60includes a lid62, a filter section64, a heater section66, and a sensor section68. The lid62is detachably coupled to the storage unit20. The lid62is mounted in a water tight manner on the storage unit20, including a watertight member162. As a non-limiting example, the watertight member162may be an O-ring. Referring toFIG.9A, the filter section64is coupled to the lid62. The filter section64includes a filter164and a filter discharge port264. The filter164is located inside the storage unit20to filter the injection water from the storage unit20. The filter discharge port264is configured to allow the injection water flowing through the filter164to flow to the suction port146through a suction line72. According to an embodiment of the present disclosure, the filter discharge port264is coupled to the lid62, and more specifically is coupled to pass through the lid62. As a non-limiting example, the filter164may be a string wound filter. A process in which the filter section64is mounted on the lid62is illustrated inFIG.9B. The filter section64may be rotatably fitted downward from above the lid62. According to an embodiment of the present disclosure, the lid62includes fixing members262, and the filter section64includes a fastening flange364that can be coupled with the fixing members262. The fastening flange364may be detachably inserted into the fixing members262, including fastening protrusions1364that are snap-fit structures. For example, the fixing members262may be provided only to parts of a circumference of an insertion hole of the filter section64. The fixing members262and the fastening protrusions1364may be coupled by a snap-fit method while being rotated after being inserted into the insertion hole of the filter section64. According to the present disclosure, the filter section64can be easily mounted/demounted to/from the lid62so that it may be easily assembled and maintenance is convenient when the filter is replaced. Referring toFIG.8again, the heater section66is also coupled to the lid62. The heater section66functions to adjust the temperature of the injection water in the storage unit20. For example, when the injection water is frozen, the heater section66functions to heat and remove ice formation in the injection water of the storage unit20. As a non-limiting example, the heater section66may be a coil heater. The heater section66may be supplied with power through a connector166that protrudes outward from the storage unit20. The heater section66is disposed adjacent to the filter section164to surround the filter section164, and heats radially the inside and outside of the filter164and around the filter164. Thus, stable water supply is possible, for instance, in the winter season when a temperature is low. The sensor section68is configured to provide fundamental information by which the management unit60manages the injection water stored in the storage unit20. According to an embodiment of the present disclosure, the sensor section68includes a sensor for measuring the temperature of the injection water and a sensor for measuring the level of the injection water remaining in the storage unit20. To this end, according to an embodiment of the present disclosure, as illustrated inFIG.10, the sensor section68includes a sensor body168, a float268, a reed switch368, and a thermistor468. The sensor body168is disposed to be immersed in the storage unit20and is fixed to the lid62, along with the filter section64and the heater section66. The sensor body168serves to protect internal sensing parts. According to the present disclosure, the reed switch368and the thermistor468may be over molded onto the sensor body168to minimize water contact. Thus, it is possible to prevent corrosion, reduce cost, and improve reliability. The level of the injection water remaining in the storage unit20may be measured by a magnetic float level sensor. To this end, according to an embodiment of the present disclosure, the float268and the reed switch368are configured to measure the level of the injection water in the storage unit20. The float268is configured to be movable along the sensor body168to float on the level of the injection water and includes a magnet1268therein. When the magnet1268vertically moves along the sensor body168, the reed switch368inside the sensor body168is turned on or off to measure a level of water. In other words, the magnetic float level sensor well-known as a water level measurement sensor may be applied. Meanwhile, the sensor body168includes the thermistor468. The thermistor468may measure the temperature of the injection water of the storage unit20. According to the present disclosure, the management unit60is configured as a compact integrated module in which the filter section64, the heater section66, and the sensor section68are mounted on the single lid62. Especially, the lid62of the management unit60is disposed at an upper end of the storage unit20. Thereby, damage to the management unit60can be prevented by reducing a direct influence range of stress caused by volumetric expansion when water is frozen in the winter season. A structure of this management unit60can simplify an assembly process and make maintenance more convenient and easier. As illustrated inFIG.11, the integrated controller100is configured to control the device1for supplying injection water. A pressure in the pump housing244or the discharge port246detected by the pressure sensor446is transmitted to the integrated controller100. The integrated controller100transmits the collected pressure information to the motor controller50in real time. The motor controller50may control rotation of the motor242on the basis of the received pressure. Further, the integrated controller100receives information about the level of water of the storage unit20and information about a temperature of the injection water stored in the storage unit20from the reed switch368and the thermistor468of the sensor section68. When water needs to be refilled for the storage unit20based on the information from the reed switch368, the integrated controller100may be configured to inform the water refill is needed. For example, the integrated controller100may be configured to display a need for the water refill on an instrument panel of a vehicle. The integrated controller100may be configured to receive temperature information about water in the storage unit20from the thermistor468and to operate the heater section66as needed. When the temperature detected by the thermistor468approaches a freezing temperature, the integrated controller100may instruct the heater section66to operate. Further, the integrated controller100may drive the heater section66at preset intervals of time. For example, the integrated controller100is configured to forcibly operate the heater section66in a cycle preset according to each temperature. Multiplication of, for instance, germs can be prevented by periodically heating the water in the storage unit20. A flow of the injection water during forward and backward operations of the motor242in the device1for supplying injection water is illustrated inFIGS.12and13. As illustrated inFIG.12, when the water in the storage unit20is supplied toward the water injector11, the motor242is rotated in a forward direction. When the motor242is rotated in a forward direction, the water in the storage unit20is filtered through the filter section64, and then is discharged from the storage unit20through the discharge port264. The water flowing through the discharge port264flows into the suction port146of the pump-side cap46along the suction line72and flows to the injection water supply line13along the discharge line74through the discharge port246. The flowing water is injected adjacent to an intake port of the engine5by the water injector11. As illustrated inFIG.13, to collect back the water remaining in the injection water supply line13, the motor242is rotated in a backward direction. Due to a negative pressure generated by the backward rotation of the motor242, the water of the injection water supply line13flows into the pump-side cap46through the discharge port246. The water flowing into the pump-side cap46may be retransferred to the storage unit20through the bypass line76connected to the bypass port346and/or the suction line72connected to the suction port146. The device for supplying injection water according to the present disclosure can improve the fuel efficiency of the vehicle and realize a reduction in cost. The present disclosure described above is not limited to the above-described embodiments and the accompanying drawings. It should be apparent to a person having ordinary skill in the art to which the present disclosure pertains that various substitutions, modifications, and alterations are possible without departing from the technical idea of the present disclosure. | 22,127 |
11859581 | Throughout the drawings and the detailed description, the same reference numerals refer to the same elements. The drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience. DETAILED DESCRIPTION This description provides a comprehensive understanding of the methods, apparatuses, and/or systems described. Modifications and equivalents of the methods, apparatuses, and/or systems described are apparent to one of ordinary skill in the art. Sequences of operations are exemplary, and may be changed as apparent to one of ordinary skill in the art, with the exception of operations necessarily occurring in a certain order. Descriptions of functions and constructions that are well known to one of ordinary skill in the art may be omitted. Exemplary embodiments may have different forms, and are not limited to the examples described. However, the examples described are thorough and complete, and convey the full scope of the disclosure to one of ordinary skill in the art. In this specification, “at least one of A and B” should be understood to mean “only A, only B, or both A and B.” An embodiment of the present disclosure will now be described with reference to the drawings. Summary of Internal Combustion Engine As shown inFIG.1, a vehicle300includes an internal combustion engine10. The internal combustion engine10is a driving force of the vehicle300. The internal combustion engine10includes a cylinder block81, cylinders11, pistons17, connecting rods19, a crank chamber83, and a crankshaft18.FIG.1shows only one of the cylinders11. The same applies to the pistons17and the connecting rods19. The number of the cylinders11is four. Each cylinder11is a space defined in a cylinder block81. In the cylinder11, the air-fuel mixture of intake air and fuel burns. The crank chamber83is a space defined by the cylinder block81and an oil pan (not shown). The crank chamber83is located below the cylinders11. The crank chamber83connects to the cylinders11. The crank chamber83accommodates the crankshaft18. Each piston17is disposed in a corresponding cylinder11. The piston17is located in the cylinder11. The piston17reciprocates in the cylinder11. The piston17is coupled to the crankshaft18by the connecting rod19. As the piston17operates, the crankshaft18rotates. The internal combustion engine10includes a cylinder head82, ignition plugs16, and fuel injection valves15.FIG.1shows only one of the ignition plugs16. The same applies to the fuel injection valves15. The ignition plugs16and the fuel injection valves15are attached to the cylinder head82. Each ignition plug16is disposed in a corresponding cylinder11. The ignition plug16ignites the air-fuel mixture in the cylinder11. Each fuel injection valve15is disposed in a corresponding cylinder11. The fuel injection valve15directly injects fuel into the cylinder11without using an intake passage12, which will be described below. The internal combustion engine10includes the intake passage12and a throttle valve3. The intake passage12is a passage into which intake air is drawn into each cylinder11. The intake passage12is connected to the cylinders11. Specifically, the downstream portion of the intake passage12has intake ports12A defined in the cylinder head82. The intake passage12branches into intake ports12at a certain position.FIG.1shows only one of the intake ports12A. Each intake port12A is disposed in a corresponding cylinder11. The intake port12A is connected to the cylinder11. The throttle valve3is located upstream of the intake ports12A in the intake passage12. The throttle valve3regulates an amount GA of the intake air flowing through the intake passage12. The internal combustion engine10includes water injection valves14. Each water injection valve14is disposed in a corresponding cylinder11. The water injection valves14are attached to the cylinder head82. The tip of each water injection valve14is located in a corresponding intake port12A. The water injection valve14injects water into the intake port12A. The water injected by the water injection valve14flows through the intake port12A into the cylinder11. The internal combustion engine10includes an exhaust passage13. The exhaust passage13is a passage out of which exhaust gas is discharged from the cylinders11. The exhaust passage13is connected to the cylinders11. The upstream portion of the exhaust passage13has exhaust ports13A defined in the cylinder head82.FIG.1shows only one of the exhaust ports13A. The internal combustion engine10includes a valvetrain for intake air. The valvetrain for intake air includes intake valves23, an intake rocker arm86, an intake camshaft25, and an intake valve timing varying device27. The valvetrain for intake air is attached to the cylinder head82.FIG.1shows only one of the intake valves23. The same applies to the intake rocker arms86. Each intake valve23is disposed in a corresponding intake port12A. The intake valve23is located at a connection port between the intake port12A and the cylinder11. The intake valve23is coupled to the intake camshaft25by the intake rocker arm86. As the intake camshaft25rotates, the intake valve23operates to selectively open and close the connection port between the intake port12A and the cylinder11. Rotation of the crankshaft18is transmitted to the intake camshaft25. That is, the intake camshaft25rotates in conjunction with the crankshaft18. The intake valve timing varying device27changes the rotation position of the crankshaft18relative to the rotation position of the intake camshaft25(hereinafter referred to as the crank position Scr). This changes the timing of selectively opening and closing the intake valve23relative to the crank position Scr. The intake valve timing varying device27is, for example, an electric device that is driven by an electric motor. The internal combustion engine10includes a valvetrain for exhaust gas. The valvetrain for exhaust gas includes exhaust valves24, an exhaust rocker arm87, an exhaust camshaft26, and an exhaust valve timing varying device28. The valvetrain for exhaust gas is attached to the cylinder head82.FIG.1shows only one of the exhaust valve24. The same applies to the exhaust rocker arms87. Each exhaust valve24is disposed in a corresponding exhaust port13A. The exhaust valve24is located at a connection port between the exhaust port13A and the cylinder11. The exhaust valve24is coupled to the exhaust camshaft26by the exhaust rocker arm87. As the exhaust camshaft26rotates, the exhaust valve24operates to selectively open and close the connection port between the exhaust port13A and the cylinder11. Rotation of the crankshaft18is transmitted to the exhaust camshaft26. That is, the exhaust camshaft26rotates in conjunction with the crankshaft18. The exhaust valve timing varying device28changes the rotation position of the exhaust camshaft26relative to the crank position Scr. This changes the timing of selectively opening and closing the exhaust valve24relative to the crank position Scr. The exhaust valve timing varying device28is, for example, an electric device that is driven by an electric motor. The internal combustion engine10includes a water supply mechanism70. The water supply mechanism70includes a tank78, a supply passage74, a pump77, branch passages75, return passages79, and adjustment valves76. The tank78stores water. The supply passage74extends from the tank78. Each branch passage75is disposed in a corresponding water injection valve14. The branch passages75branch from the supply passage74. Each branch passage75is connected to a corresponding water injection valve14. The pump77is located in the supply passage74. The pump77is an electric pump that is driven by an electric motor. The pump77forcibly delivers water from the tank78to the branch passages75through the supply passage74. Each return passage79is disposed in a corresponding branch passage75. The return passage79connects the branch passage75to the tank78. The return passage79is a passage through which water returns from the branch passage75into the tank78. InFIG.1, the return passages79are shown by the dotted lines. Each adjustment valve76is disposed in a corresponding return passage79. The adjustment valve76is located in the return passage79. The adjustment valve76is an electric valve that is driven by an electric motor. The adjustment valve76is of a butterfly type. That is, an open degree D of the adjustment valve76is adjustable. Depending on the open degree D of the adjustment valve76, the flow passage area of the return passage79changes. Further, a change occurs in the amount of water that returns to the tank78through the return passage79. Furthermore, a change occurs in the pressure in a portion of the branch passage75downstream of the part connected to the return passage79(i.e., the pressure of water supplied to the water injection valve14). That is, the adjustment valve76is a pressure adjustment device that adjusts the pressure of water supplied to the water injection valve14. Depending on the open degree D of each adjustment valve76, the pressure of the water supplied to a corresponding water injection valve14changes. The open degrees D of the adjustment valves76can be adjusted individually. The internal combustion engine10includes a crank position sensor34, an intake cam position sensor36, an exhaust cam position sensor35, and an air flow meter31. The crank position sensor34detects the crank position Scr. The intake cam position sensor36detects a rotation position CG of the intake camshaft25. The exhaust cam position sensor35detects a rotation position CE of the exhaust camshaft26. The air flow meter31is located upstream of the throttle valve3in the intake passage12. The air flow meter31detects the amount GA of the intake air flowing through the portion of the intake passage12where the air flow meter31is disposed. These sensors each repeatedly send a signal corresponding to the detected information to a controller100(described later). The internal combustion engine10includes water pressure sensors30and open degree sensors32.FIG.1shows only one of the water pressure sensors30. The same applies to the open degree sensors32. Each water pressure sensor30is disposed in a corresponding branch passage75. Each water pressure sensor30detects a pressure WP of the water supplied to a corresponding water injection valve14(hereinafter referred to as water pressure WP). Each open degree sensor32is disposed in a corresponding adjustment valve76. Each open degree sensor32detects the open degree D of a corresponding adjustment valve76. These sensors each repeatedly send a signal corresponding to the detected information to the controller100(described later). The vehicle300includes an accelerator sensor38and a vehicle speed sensor39. The accelerator sensor38detects an accelerator operation amount ACC, which is the depression amount of the accelerator pedal of the vehicle300. The vehicle speed sensor39detects a vehicle speed SP, which is the travel speed of the vehicle300. These sensors each repeatedly send a signal corresponding to the detected information to the controller100(described later). Schematic Configuration of Controller As shown inFIG.1, the vehicle300includes the controller100. The controller100may include processing circuitry including one or more processors that execute various processes in accordance with a computer program (software). The controller100may include processing circuitry that includes one or more dedicated hardware circuits such as application specific integrated circuits (ASICs) that execute at least part of various processes or may include processing circuitry that includes a combination of the processors and the dedicated hardware circuits. The processor includes a CPU111and a memory112, such as a RAM or a ROM. The memory112stores program codes or instructions configured to cause the CPU111to execute the processes. The memory112, or a computer-readable medium, includes any type of media that are accessible by general-purpose computers and dedicated computers. The memory112is, an electrically-rewriteable non-volatile memory. The controller100repeatedly receives detection signals from the various sensors of the vehicle300. Based on the received detection signals, the controller100calculates the following parameters when necessary. Based on the crank position Scr detected by the crank position sensor34, the controller100calculates an engine rotation speed NE, which is the rotation speed of the crankshaft18. Based on the engine rotation speed NE and the amount GA of the intake air detected by the air flow meter31, the controller100calculates the engine load factor KL. The engine load factor KL is the ratio of the current cylinder inflow air amount to a cylinder inflow air amount obtained during steady operation of the internal combustion engine10with the throttle valve3fully open at the current engine rotation speed NE. The cylinder inflow air amount refers to the amount of the intake air flowing into one cylinder11in the intake stroke. The controller100controls the internal combustion engine10. Based on the accelerator operation amount ACC, the vehicle speed SP, the engine rotation speed NE, the engine load factor KL, and the like, the controller100performs various types of control on the internal combustion engine10(e.g., fuel injection by the fuel injection valves15, the ignition timings of the ignition plugs16, the adjustment of the open degree of the throttle valve3). By performing such control, the controller100causes air-fuel mixture to sequentially burn in the cylinders11. As part of the various control of the internal combustion engine10, the controller100controls the timing of the opening and closing of the intake valves23(hereinafter referred to as the intake valve timing) and the timing of the opening and closing of the exhaust valves24. For example, the controller100executes the following control related to the control of the intake valve timing. In the present embodiment, the controller100treats, as 0 (initial value), a state in which the intake valve timing is most retarded. By adjusting the advancement amount of the intake valve timing from the initial value, the controller100adjusts the intake valve timing. To adjust the intake valve timing, the controller100calculates a target advancement amount, which is a target value of the advancement amount of the intake valve timing, based on the engine rotation speed NE, the engine load factor KL, and the like. Then, the controller100controls the intake valve timing varying device27such that the advancement amount of an actual intake valve timing coincides with the target advancement amount. The controller100stores, in advance, the crank position Scr at which the intake valve23of each cylinder11reaches a valve-opening time TS when the intake valve timing has the initial value. Thus, by calculating a crank position Scr that is advanced from the valve-opening crank position Scr by the target advancement amount, the controller100obtains the current crank position Scr at which the intake valve23reaches the valve-opening time TS. Likewise, the controller100stores, in advance, the crank position Scr at which the intake valve23of each cylinder11reaches a valve-closing time TC when the intake valve timing has the initial value. This allows the controller100to obtain the current crank position Scr at which the intake valve23reaches the valve-closing time TC. In such a manner, the controller100uses the crank position Scr corresponding to the initial value and the target advancement amount to constantly obtain the crank position Scr at which the intake valve23of each cylinder11reaches the valve-closing time TS and the crank position Scr at which the intake valve23reaches the valve-closing time TC. Summary of Water Injection Control The controller100is capable of executing water injection control. The water injection control is executed to control the ignition timing, injection amount, and injection pressure of the water from each water injection valve14. In the present embodiment, a single combustion cycle is defined as a period from when the intake valve23of a specific cylinder11closes to when the intake valve23closes again after opening. That is, as shown inFIG.2, the single combustion cycle is a period from the valve-closing time TC, at which the intake valve23closes, to a valve-closing time TCA, at which the intake valve23closes again after the elapse of the valve-opening time TS, at which the intake valve23opens. In the single combustion cycle, the specific cylinder11enters each of the compression stroke, the expansion stroke, the exhaust stroke, and the intake stroke. The period during which the intake valve23is closed (i.e., the period from the valve-closing time TC to the valve-opening time TS of the intake valve23) is hereinafter referred to as a valve-closed period U1of the intake valve23. The period during which the intake valve23is open (i.e., the period from the valve-opening time TS to the valve-closing time TCA of the intake valve23) is hereinafter referred to as a valve-open period U2of the intake valve23. As part of the water injection control, the controller100can execute a target calculation process. In the target calculation process, the running state of the internal combustion engine10is used to calculate a target injection amount Qs. The target injection amount Qs is a target value of the amount of water supplied to one cylinder11during the single combustion cycle. The controller100stores, in advance, a target water amount map M1as the information used to calculate the target injection amount Qs. The target water amount map M1represents the relationship between the engine rotation speed NE, the engine load factor KL, and a requested water amount. The requested water amount is the amount of water that needs to be supplied to one cylinder11in the single combustion cycle. In the target water amount map M1, the engine rotation speed NE, the engine load factor KL, and the requested water amount have the following relationship. When the engine load factor KL is less than a set load factor (described below), the requested water amount is 0 regardless of whether the engine rotation speed NE is relatively high or low. When the engine load factor KL is greater than or equal to the set load factor, the requested water amount is greater than 0 regardless of whether the engine rotation speed NE is relatively high or low. Specifically, when the engine load factor KL is greater than or equal to the set load factor, the requested water amount becomes larger as the engine load factor KL becomes higher at a certain engine rotation speed NE. The water injected by the water injection valve14evaporates in the cylinder11. When the water evaporates, the heat of vaporization lowers the temperature in the cylinder11. The requested water amount that is set for the target water amount map M1has a value allowing for cooling in the cylinder11that is requested depending on each engine running state. Further, the set load factor is the lowest value of the engine load factor KL at which the temperature in the cylinder11needs to be lowered through the supply of water from the water injection valve14. The target water amount map M1is created based on, for example, experiments or simulations. As part of the water injection control, the controller100can execute a determination process. The determination process is a process that determines whether the target injection amount Qs of water can be supplied from the water injection valve14to the cylinder11during the valve-open period U2of the intake valve23in the single combustion cycle. The maximum value of the amount that can be supplied to each cylinder11by injecting water from a corresponding water injection valve14during the valve-open period U2of the intake valve23in the single combustion cycle is hereinafter referred to as an allowable injection amount Qv. The allowable injection amount Qv is determined based on a prior condition in which the water pressure WP has a value used for a first injection process (described later). In the determination process, the controller100determines whether the allowable injection amount Qv is greater than or equal to the target injection amount Qs. The controller100stores, in advance, a reach period L as the information needed to calculate the allowable injection amount Qv. The reach period L is the length of time from when the water injection valve14injects water to when the water reaches the inside of the cylinder11. The reach period L is defined based on, for example, experiments or simulations. In the present embodiment, the reach period L has a fixed value. The controller100further stores, in advance, an injection map M2as the information needed to calculate the allowable injection amount Qv. The amount of water injected by one water injection valve14over a certain injection period under a certain water pressure WP is hereinafter referred to as a possible injection amount. The possible injection amount changes depending on the injection period. As described above, the injection period is a period during which the water injection valve14continues to inject water. The injection map M2represents the relationship between the injection period, the water pressure WP, and the possible injection amount. In the injection map M2, the injection period, the water pressure WP, and the possible injection amount have the following relationship. At a certain water pressure WP, the possible injection amount becomes larger as the injection period becomes longer. In a certain injection period, the possible injection amount becomes larger as the water pressure WP becomes higher. The injection map M2is created based on, for example, experiments or simulations. As part of the water injection control, the controller100can execute the first injection process and a second injection process. The first injection process is a process that causes the water injection valve14to inject water during the valve-open period U2of the intake valve23in the single combustion cycle. The second injection process is a process that causes the water injection valve14to inject water during the valve-closed period U1of the intake valve23in the single combustion cycle. When the determination result of the determination process is affirmative, the controller100executes only the first injection process. In this case, the controller100causes the water injection valve14to inject the target injection amount Qs of water through the first injection process. When the determination result of the determination process is negative, the controller100executes the first and second injection processes as shown inFIG.2. In this case, the controller100causes the water injection valve14to inject the allowable injection amount Qv of water through the first injection process and causes the water injection valve14to inject the set injection amount Qr of water through the second injection process. The set injection amount Qr is the amount of the difference between the allowable injection amount Qv and the target injection amount Qs. In this manner, when the determination result of the determination process is negative, the controller100executes the two injection processes so that the water injection valve14injects the target injection amount Qs of water. As shown inFIG.2, the controller100sets a different water pressure WP for each of the first and second injection processes. Specifically, the controller100controls the adjustment valve76such that the water pressure WP becomes a first value WP1during the execution of the first injection process. The controller100controls the adjustment valve76such that the water pressure WP becomes a second value WP2during the execution of the second injection process. The second value WP2is higher than the first value WP1. That is, the controller100controls the adjustment valve76such that the water pressure WP becomes higher in the second injection process than in the first injection process. This means that the controller100sets the injection pressure of water from the water injection valve14to be higher in the second injection process than in the first injection process. The first value WP1is predetermined through, for example, experiments or simulations. The second value WP2is predetermined through, for example, experiments or simulations. The controller100stores the first value WP1and the second value WP2in advance. The reason for changing the water pressure WP between the first and second injection processes will be described in the Operation section. The details of the first value WP1and the second value WP2will also be described. In the present embodiment, the controller100sets the water pressure WP to the first value WP1over the entire period during which the first injection process is executed. The controller100sets the water pressure WP to the second value WP2over the entire period during which the second injection process is executed. To control the water pressure WP depending on each injection process, the controller100substantially changes the open degree D of each adjustment valve76. The state in which the amount of water discharged by the pump77is a constant set discharge amount is referred to as a first state. The open degree D of the adjustment valve76needed to set the water pressure WP to the first value WP1in the first state is referred to as a first open degree D1. The open degree D of the adjustment valve76needed to set the water pressure WP to the second value WP2in the first state is referred to as a second open degree D2. The rotation speed of the pump77needed to set the discharge amount of the pump77to the set discharge amount is referred to as a set rotation speed. The controller100stores the first open degree D1, the second open degree D2, and the set rotation speed in advance. The first open degree D1, the second open degree D2, and the set rotation speed are defined based on, for example, experiments or simulations, with the flow passage area of the adjustment valve76corresponding to the adjustment valve76and the discharging performance of the pump77taken into account. To change the open degree D of the adjustment valve76to the first open degree D1or the second open degree D2, the controller100refers to a detection value of the open degree sensor32as necessary and controls the electric motor of the adjustment valve76such that the requested open degree D is obtained. As part of the water injection control, the controller100can execute a first injection time calculation process. The first injection time calculation process is a process that calculates a start time of the first injection process (hereinafter referred to as the first start time V1A) and an end time of the first injection process (hereinafter referred to as the first end time V1B). As shown inFIG.2, the controller100sets the valve-opening time TS of the intake valve23to the first start time V1A in the first injection time calculation process. Further, the controller100sets the first end time V1B to be before a limit time in the first injection time calculation process. The limit time is before the valve-closing time TCA of the intake valve23by the reach period L. The valve-closing time TCA of the intake valve23is the end time of the single combustion cycle. As part of the water injection control, the controller100can execute a second injection time calculation process. The second injection time calculation process is a process that calculates a start time of the second injection process (hereinafter referred to as the second start time V2A) and an end time of the second injection process (hereinafter referred to as the second end time V2B). In the second injection time calculation process, the controller100determines the second start time V2A such that the second injection process ends before the first start time V1A by a specified period K. To make such a determination, the controller100sets the second start time V2A and the second end time V2B as follows. The controller100sets the second end time V2B to be before the first start time V1A by the specified period K. Further, the controller100sets the second start time V2A to be before the second end time V2B by a period needed for the injection of the set injection amount Qr of water from the water injection valve14. The minimum period for changing the water pressure WP from the second value WP2to the first value WP1is referred to as the necessary period. The necessary period is a period for changing the open degree D of the adjustment valve76from the second open degree D2to the first open degree D1. In the present embodiment, the controller100sets the specified period K to the necessary period. The controller100stores the necessary period in advance. The necessary period is defined in advance through, for example, experiments or simulations. The changes in the water pressure WP shown inFIG.2and the flow of the injection processes will be described in detail below in the Operation section. Detailed Processing Content of Water Injection Control The series of processes related to the water injection control described below are executed for one cylinder11. That is, the controller100executes the following series of processes related to the water injection control for each cylinder11(i.e., each water injection valve14). When the internal combustion engine10is running (i.e., when the engine rotation speed NE is greater than 0), the controller100repeatedly executes the water injection control. For each cylinder11, the controller100executes the series of processes related to the water injection control once in the single combustion cycle. In each combustion cycle, the controller100starts the water injection control at the start time of the single combustion cycle (i.e., the valve-closing time TC of the intake valve23). Based on the newest crank position Scr received from the crank position sensor34, the controller100determines the time of starting the water injection control. That is, when the newest crank position Scr coincides with the crank position Scr at which the intake valve23reaches the valve-closing time TC, the controller100determines that the intake valve23has reached the valve-closing time TC. Although the details will not be described, the valve-closing time TC and the valve-opening time TS of the intake valve23referred to and used by the controller100in the series of processes of the water injection control are related to the cylinder11for which the water injection control is executed. While the internal combustion engine10is running, the controller100controls the pump77such that the rotation speed of the pump77coincides with the set rotation speed. At the point in time when the internal combustion engine10is started, the controller100controls the adjustment valve76such that the open degree D of the adjustment valve76coincides with the first open degree D1. Thus, when the water injection control is executed for the first time after the internal combustion engine10is started, the open degree D of the adjustment valve76at the point in time when the water injection control is started is the first open degree D1. As shown inFIG.3, when starting the water injection control, the controller100first executes the process of step S110. In step S110, the controller100calculates the target injection amount Qs. Specifically, the controller100refers to the newest engine rotation speed NE, the newest engine load factor KL, and the target water amount map M1. As described above, the target water amount map M1represents the relationship between the engine rotation speed NE, the engine load factor KL, and the requested water amount, which is the amount of water that needs to be supplied to the cylinder11. Based on the target water amount map M1, the controller100calculates, as the target injection amount Qs, the requested water amount corresponding to the newest engine rotation speed NE and the newest engine load factor KL. Subsequently, the controller100advances the process to step S120. The process of step S110is the target calculation process. In step S120, the controller100calculates the allowable injection amount Qv. As described below, the allowable injection amount Qv is the amount of water that can be injected by the water injection valve14during a period in the valve-open period U2of the intake valve23excluding the reach period L. As described above, the reach period L is the length of time to when the water injected by the water injection valve14reaches the inside of the cylinder11. To calculate the allowable injection amount Qv, the controller100first uses the newest engine rotation speed NE to convert the reach period L into a crank rotation amount corresponding to the newest engine rotation speed NE. Then, the controller100sets the obtained crank rotation amount as an offset value. The crank rotation amount represents the rotation angle of the crankshaft18obtained when the crankshaft18rotates from a rotation position to another rotation position. The higher the engine rotation speed NE, the larger the offset value. After calculating the offset value, the controller100calculates a limit crank position. Specifically, the controller100calculates the crank position Scr before, by the offset value, the crank position Scr at which the intake valve23reaches the valve-closing time TCA as the limit crank position. As shown inFIG.2, the valve-closing time TCA is the end time of the current combustion cycle. After calculating the limit crank position, the controller100calculates an allowable rotation amount. The allowable rotation amount is a crank rotation amount obtained from the crank position Scr at which the intake valve23reaches the valve-opening time TS to the limit crank position. After calculating the allowable rotation amount, the controller100uses the newest engine rotation speed NE to convert the allowable rotation amount into the length of a time that corresponds to the newest engine rotation speed NE. Then, the controller100sets the obtained value as an allowable period. At the same allowable rotation amount, the higher the engine rotation speed NE, the shorter the allowable period. Subsequently, the controller100refers to the injection map M2and the first value WP1, which is the water pressure WP used for the first injection process. As described above, the injection map M2represents the relationship between the injection period, the water pressure WP, and the possible injection amount. The controller100uses the injection map M2to calculate, as the allowable injection amount Qv, the possible injection amount corresponding to the first value WP1and the allowable period. In this case, the controller100only needs to apply the allowable period to the injection period in the injection map M2. As shown inFIG.3, after calculating the allowable injection amount Qv, the controller100advances the process to step S130. In step S130, the controller100determines whether the allowable injection amount Qv calculated in step S120is greater than or equal to the target injection amount Qs calculated in step S110. When this determination is affirmative, the target injection amount Qs of water can be supplied to the cylinder11from the water injection valve14during the valve-open period U2of the intake valve23in the single combustion cycle. When the allowable injection amount Qv is greater than or equal to the target injection amount Qs (step S130: YES), the controller100advances the process to step S140. The process of step S130is the determination process. In step S140, the controller100calculates the first injection time. Specifically, the controller100calculates the first start time V1A, which is the start time of the first injection process, and the first end time V1B, which is the end time of the first injection process. First, the controller100calculates the first start time V1A. Specifically, the controller100sets the crank position Scr of the first start time V1A to the crank position Scr at which the intake valve23reaches the valve-opening time TS. Next, the controller100calculates the first end time V1B. Specifically, the controller100refers to the first value WP1, which is the water pressure WP for the first injection process, the target injection amount Qs calculated in step S110, and the injection map M2. The controller100uses the injection map M2to calculate, as a normal injection period, the injection period corresponding to the first value WP1and the target injection amount Qs. Subsequently, the controller100uses the newest engine rotation speed NE to convert the normal injection period into a crank rotation amount corresponding to the newest engine rotation speed NE. The controller100sets the obtained value as a normal rotation amount. Then, the controller100calculates, as the crank position Scr of the first end time V1B, the crank position Scr retarded from the crank position Scr of the first start time V1A by the normal rotation amount. After calculating the first end time V1B, the controller100advances the process to step S150. The process of step S140is the first injection time calculation process. After starting the water injection control, the controller100immediately executes the processes of step S110to S140. Thus, the time at which the process is advanced to the next step S150is substantially equal to the time at which the single combustion cycle starts. In step S150, the controller100executes the first injection process. Specifically, the controller100waits until the first start time V1A calculated in step S140. When the first start time V1A is reached, the controller100causes the water injection valve14to start injecting water. Then, the controller100continues the water injection until the first end time V1B calculated in step S140. When the first end time V1B is reached, the controller100causes the water injection valve14to stop injecting water. During the execution of the first injection process, the water pressure WP has the first value WP1in relation to the process of step S260in which the previous water injection control was executed. To start the first injection process in step S150, the controller100determines in the following manner that the first start time V1A is reached. The controller100repeatedly refers to the newest crank position Scr received from the crank position sensor34. Then, when determining that the newest crank position Scr coincides with the crank position Scr of the first start time V1A, the controller100determines that the first start time V1A is reached. In the same manner, when determining that the newest crank position Scr coincides with the crank position Scr of the first end time V1B, the controller100determines that the first end time V1B is reached. After executing the first injection process, the controller100temporarily ends the series of processes related to the water injection control. When the start time of the single combustion cycle is reached, the controller100executes the process of step S110again. When determining that the allowable injection amount Qv is less than the target injection amount Qs (step S130: NO), the controller100advances the process to step S210. In step S210, the controller100calculates the first injection time. That is, the controller100calculates the first start time V1A and the first end time V1B in the same manner as step S140. In step S210, the controller100sets the crank position Scr of the first start time V1A to the crank position Scr at which the valve-opening time TS of the intake valve23is reached. The controller100sets the first end time V1B as follows. The controller100sets the crank position Scr of the first end time V1B to the limit crank position calculated in correspondence with the calculation of the allowable injection amount Qv in step S120. Subsequently, the controller100advances the process to step S220. The process of step S210is the first injection time calculation process. In step S220, the controller100calculates the set injection amount Qr, which is the difference between the target injection amount Qs and the allowable injection amount Qv. Specifically, the controller100sets the set injection amount Qr to a value obtained by subtracting the allowable injection amount Qv from the target injection amount Qs. Then, the controller100advances the process to step S230. In step S230, the controller100calculates the second injection time. Specifically, the controller100calculates the second start time V2A, which is the start time of the second injection process, and the second end time V2B, which is the end time of the second injection process. The controller100first calculates the second end time V2B. Specifically, the controller100refers to the necessary period stored in advance and the newest engine rotation speed NE. Then, the controller100uses the newest engine rotation speed NE to convert the necessary period into a crank rotation amount corresponding to the newest engine rotation speed NE. The controller100sets the obtained crank rotation amount as a necessary rotation amount. The higher the engine rotation speed NE, the larger the necessary rotation amount. Subsequently, the controller100calculates the crank position Scr before, by the necessary rotation amount, the crank position Scr of the first start time V1A calculated in step S210as the crank position Scr of the second end time V2B. Next, the controller100calculates the second start time V2A. Specifically, the controller100refers to the second value WP2, which is the water pressure WP for the second injection process, the set injection amount Qr calculated in step S220, and the injection map M2. The controller100uses the injection map M2to calculate, as a set injection period, the injection period corresponding to the second value WP2and the set injection amount Qr calculated in step S220. Subsequently, the controller100uses the newest engine rotation speed NE to convert the set injection period into a crank rotation amount corresponding to the newest engine rotation speed NE. Then, the controller100sets the obtained crank rotation amount as the set rotation amount. In the same manner as the necessary rotation amount, the higher the engine rotation speed NE, the larger the set rotation amount during the same set injection period. Then, the controller100calculates the crank position Scr before, by the set rotation amount, the crank position Scr of the calculated second end time V2B as the crank position Scr of the second start time V2A. After calculating the second start time V2A, the controller100advances the process to step S240. The process of step S230is the second injection time calculation process. In the same manner as step S140, after starting the water injection control, the controller100immediately executes the processes of step S110to S230. Thus, the time at which the process is advanced to the next step S240is substantially equal to the time at which the single combustion cycle starts. In step S240, the controller100changes the water pressure WP to the second value WP2. The water pressure WP at the point in time when the process is advanced to S240has the first value WP1in relation to the process of step S260in which the previous water injection control was executed. The open degree D of the adjustment valve76is the first open degree D1. Specifically, in the process of step S240, the controller100controls the adjustment valve76such that the open degree D of the adjustment valve76coincides with the second open degree D2. The open degree D of the adjustment valve76is accordingly changed from the first open degree D1to the second open degree D2. After executing the process of step S240, the controller100advances the process to step S250. In step S250, the controller100executes the second injection process. Specifically, the controller100waits until the second start time V2A calculated in step S230. When the second start time V2A is reached, the controller100causes the water injection valve14to start injecting water. Then, the controller100continues the water injection until the second end time V2B calculated in step S230. When the second end time V2B is reached, the controller100causes the water injection valve14to stop injecting water. The determination of the second start time V2A and the second end time V2B is made in the same manner as step S150. After calculating the second injection process, the controller100advances the process to step S260. In step S260, the controller100changes the water pressure WP from the second value WP2to the first value WP1. Specifically, the controller100controls the adjustment valve76such that the open degree D of the adjustment valve76coincides with the first open degree D1. The open degree D of the adjustment valve76is accordingly changed from the second open degree D2to the first open degree D1. The change in the open degree requires the necessary period (i.e., the specified period K of the present embodiment). After executing the process of step S260, the controller100advances the process to step S270. In the setting of the second end time V2B, the crank position Scr at the point in time when the process is advanced to the next step S270is the crank position Scr of the first start time V1A. In step S270, the controller100executes the first injection process. Specifically, when the process is advanced to step S270, the controller100immediately causes the water injection valve14to start injecting water. Then, the controller100continues the water injection until the first end time V1B calculated in step S210. When the first end time V1B is reached, the controller100causes the water injection valve14to stop injecting water. The determination of the first start time V1A and the first end time V1B is made in the same manner as step S150. After executing the first injection process, the controller100temporarily ends the series of processes related to the water injection control. When the start time of the single combustion cycle is reached, the controller100executes the process of step S110again. Operation of Embodiment (A) Flow of Water Injection from Water Injection Valve with Water Injection Control and Change in Water Pressure At the point in time when the single combustion cycle starts (i.e., at the valve-closing time TC of the intake valve23), the open degree D of the adjustment valve76is the first open degree D1. As shown inFIG.2, the water pressure WP thus has the first value WP1at the valve-closing time TC of the intake valve23. If, for example, the target injection amount Qs is relatively large or the engine rotation speed NE is relatively high, the allowable injection amount Qv may be less than the target injection amount Qs (step S130: NO). In this case, as shown inFIG.2, at the valve-closing time TC of the intake valve23, the controller100quickly changes the open degree D of the adjustment valve76from the first open degree D1to the second open degree D2(step S240). This causes the water pressure WP to change from the first value WP1to the second value WP2. Then, as shown inFIG.2, the controller100executes the second injection process in the valve-closed period U1of the intake valve23with the water pressure WP kept at the second value WP2(step S250). Then, the controller100causes the water injection valve14to inject the set injection amount Qr of water. The controller100ends the second injection process at the second end time V2B, which is before the valve-opening time TS of the intake valve23by the specified period K. Subsequently, the controller100changes the open degree D of the adjustment valve76from the second open degree D2to the first open degree D1(step S260). This causes the water pressure WP to change from the second value WP2to the first value WP1as shown inFIG.2. The change in the water pressure WP requires the necessary period, which is set as the specified period K. Accordingly, at the point in time when the water pressure WP has been changed, the valve-opening time TS of the intake valve23is reached. As shown inFIG.2, the controller100executes the first injection process (step S270). The controller100causes the water injection valve14to inject the allowable injection amount Qv of water during the valve-open period U2of the intake valve23. By executing the first and second injection processes in this manner, the controller100causes the water injection valve14to inject the target injection amount Qs of water as a total amount in the single combustion cycle. FIG.2shows the necessary period, which is needed to change the water pressure WP from the second value WP2to the first value WP1, in an exaggerated manner to facilitate the understanding of the situation in which the water pressure WP is changed between the second injection process and the first injection process. The same applies to the period during which the water pressure WP is changed from the first value WP1to the second value WP2. The injection period of the first injection process and the injection period of the second injection process are just exemplary and do not always coincide with actual injection periods. (B) Reason for Changing Water Pressure Between First Injection Process and Second Injection Process When water is injected from the water injection valve14, the injected water may collect at one position on the wall surface of the intake port12A in a concentrated manner. In this case, the collected water forms a relatively large water droplet at that position of the wall surface of the intake port12A. Since the thickness of the liquid film formed by the water droplet is relatively large, it is difficult for the water droplet to evaporate. The water droplet remains on the wall surface of the intake port12A or flows into the cylinder11together with intake air. If the water droplet flows into the cylinder11, the water droplet runs down the wall surface of the cylinder11and eventually flows into the crank chamber83. Thus, the water droplet does not cool the inside of the cylinder11. In addition to the situation in which a relatively large water droplet formed in the intake port12A flows into the cylinder11, a relatively large water droplet may directly form on the wall surface of the cylinder11. For example, when water collects at one position on the wall surface of the cylinder11, the collected water forms a relatively large water droplet at that position on the wall surface of the cylinder11. Such a water droplet flows into the crank chamber83without evaporating in the cylinder11. Even if water evaporates, the heat of the vaporization cools the wall surface of the cylinder11but does not significantly cool the gas in the cylinder11. Thus, when a relatively large water droplet with a relatively large thickness liquid film is formed in the intake port12A or the cylinder11, the water droplet does not achieve evaporative cooling of the gas in the cylinder11. Accordingly, even when the water injection valve14injects the target injection amount Qs of water, the formation of a relatively large water droplet as described above cannot cool the inside of the cylinder11as intended. To solve this problem, the present embodiment improves the water injection control to prevent the formation of a relatively large water droplet as described above. Specifically, a different water pressure WP is used for each of the first and injection processes. More specifically, the water pressure WP of the second injection process is higher than the water pressure WP of the first injection process. This means that the injection pressure of the water injection valve14is higher in the second injection process than in the first injection process. Such a configuration is employed for the reason described below. When the intake valve23is in the valve-closed period U1, the water injection valve14may inject water into the intake port12A. If the injection pressure of the water injection valve14is relatively high, the water is dispersed in every direction with momentum from an injection hole of the water injection valve14. Thus, when the injection pressure of the water injection valve14is relatively high, the water injected from the water injection valve14is widely dispersed. That is, as illustrated inFIG.4, the injection range of water with a relatively high injection pressure shown by Y1is broader than the injection range of water with a relatively low injection pressure shown by Y2. When the same amount of water is injected, the amount of water collecting at each position on the wall surface of the intake port12A becomes smaller as the injection range of water becomes broader. Thus, the thickness of the liquid film formed by the collected water is relatively small at each position on the wall surface of the intake port12A. The smaller the thickness of the liquid film, the more quickly the liquid film evaporates. Thus, increasing the injection pressure of the water injection valve14prevents the formation of a relatively water droplet on the wall surface of the intake port12A. In this point of view, the controller100sets the water pressure WP to be higher and consequently sets the injection pressure of the water injection valve14to be higher in the second injection process. In a situation in which the intake valve23is in the valve-closed period U1, the injection pressure that allows water to be dispersed so widely as to prevent the formation of a relatively large water droplet is hereinafter referred to as a second injection pressure J2. The second value WP2, which is the water pressure WP for the second injection process, is the water pressure WP used when the injection pressure of the water injection valve14is the second injection pressure J2. The second value WP2and the second injection pressure J2, on which the second value WP2is based, are values that have been defined in advance through, for example, experiments or simulations. The defining of the second injection pressure J2takes into account, for example, the pressure of intake air corresponding to the engine running state when the target injection amount Qs is greater than 0. The difference between the pressure of the intake air and the pressure of the injection from the water injection valve14may affect the injection range. As described above, increasing the injection pressure of the water injection valve14is effective for preventing the formation of a relatively water droplet on the wall surface of the intake port12A, but is not effective for preventing the formation of a relatively large water droplet on the wall surface of the cylinder11for the following reason. When the intake valve23is in the valve-open period U2, the water injection valve14may inject water with a relatively high injection pressure. In this case, as the injection range of water becomes wider, the water may reach a farther position. Additionally, the flow of intake air toward the cylinder11occurs in the valve-open period U2of the intake valve23. The flow of this intake air causes the water injected by the water injection valve14to flow toward the cylinder11. If the flow of intake air toward the cylinder11occurs and the water injection valve14injects water to a farther position, the water injected by the water injection valve14flows into the cylinder11with momentum. Further, as shown by Z1inFIG.5, the water is moved a longer distance. The water may reach the wall surface of the cylinder11. If the water locally collects on the wall surface of the cylinder11in a concentrated manner, the collected water forms a relatively large water droplet. That is, increasing the injection pressure of the water injection valve14in the valve-open period U2of the intake valve23may rather form a relatively large water droplet. In this regard, decreasing the injection pressure of the water from the water injection valve14shortens the movement distance of the water injected from the water injection valve14. This prevents situations in which the water reaches the wall surface of the cylinder11. In this point of view, the controller100sets the water pressure WP to be lower and consequently sets the injection pressure of the water injection valve14to be lower in the second injection process. In a situation in which the intake valve23is in the valve-open period U2, the injection pressure that prevents the water injected by the water injection valve14from reaching the wall surface of the cylinder11is hereinafter referred to as a first injection pressure J1. The first value WP1, which is the water pressure WP for the first injection process, is the water pressure WP used when the injection pressure of the water injection valve14is the first injection pressure J1. The first value WP1and the first injection pressure J1, on which the first value WP1is based, are values predetermined through, for example, experiments or simulations. The defining of the first injection pressure J1takes into account, for example, the amount GA of intake air corresponding to the engine running state when the target injection amount Qs is greater than 0. The amount GA of the intake air may affect the movement distance of the water injected from the water injection valve14. Advantages of Embodiment (1) When the allowable injection amount Qv is less than the target injection amount Qs, the controller100executes the first injection process during the valve-open period U2of the intake valve23and the second injection process during the valve-closed period U1of the intake valve23. In these processes, the controller100causes the water injection valve14to inject the target injection amount Qs of water in the single combustion cycle. To execute the injection processes in the valve-open period U2and the valve-closed period U1of the intake valve23in this manner, the controller100sets the water pressure WP suitable for preventing the formation of a relatively large water droplet in each injection process. This causes most of the target injection amount Qs of water injected from the water injection valve14to flow into the cylinder11in microaprtice state without becoming a relatively large water droplet. Accordingly, the present embodiment allows substantially all the target injection amount Qs of the water to evaporate in the cylinder11. (2) The controller100sets the second end time V2B, which is the end time of the second injection process, and the first start time V1A, which is the start time of the first injection process, to be before the first start time V1A by the specified period K. This provides a period during which the open degree D of the adjustment valve76is changed from the second open degree D2to the first open degree D1by the time the second injection process ends and then the first injection process starts. That is, a period for changing the water pressure WP is provided. By changing the water pressure WP between the two injection processes in this manner, the following effect is obtained. In the second injection process, the water pressure WP is kept at the second value WP2until the second end time V2B, which is the end time of the second injection process. That is, the second injection pressure J2is kept until the end time of the second injection process. In the first injection process, the water pressure WP can be set to the first value WP1from the first start time V1A, which is the start time of the first injection process. That is, the first injection pressure J1can be used from the start time of the first injection process. Thus, the controller100can use a different injection pressure for each of the entire period for executing the second injection process and the entire period for executing the first injection process. This ensures that advantage (1), which allows substantially all the target injection amount Qs of the water to evaporate in the cylinder11, is achieved. (3) To minimize the amount of water that collects on the wall surface of the intake port12A and consequently the formation of a relatively large water droplet, the following procees needs to be executed. When the water injection valve14injects water in the valve-closed period U1of the intake valve23through the second injection process, the period during which the injected water remains in the intake port12A needs to be minimized. To achieve this, the second injection process needs to be executed at a time that is as close as possible to the valve-opening time TS of the intake valve23. In the present embodiment, the specified period K from the second end time V2B to the first start time V1A is set as the necessary period, which is a minimum period needed for changing the water pressure WP. Thus, when the water pressure WP is changed between the period from the second end time V2B to the first start time V1A, the period from the second end time V2B to the first start time V1A is minimized. Accordingly, in addition to the configuration of advantage (2), in which a different injection pressure is used for each of the entire period for executing the second injection process and the entire period for executing the first injection process, the second injection process can be executed at a time as close as possible to the valve-opening time TS of the intake valve23. This is effective in preventing a relatively large water droplet from being formed on the wall surface of the intake port12A. Modifications The above embodiment may be modified as follows. The above embodiment and the following modifications can be combined as long as the combined modifications remain technically consistent with each other. The water pressure WP may be changed during the execution of the first and second injection processes. For example, when these injection processes are being executed, the running state of the internal combustion engine10may change. Further, during the execution periods of the injection processes, the injection pressure of the water injection valve14suitable for preventing the formation of a relatively large water droplet may change depending on the change in the running state. With these problems taken into account, the water pressure WP may be changed depending on the running state of the internal combustion engine10. For example, if a map representing the relationship between the running state of the internal combustion engine10and an optimal water pressure WP is created in advance, the water pressure WP can be changed during the execution of the injection processes. The specified period K is not limited to the example in the above embodiment. Instead, the specified period K does not have to be the necessary period. For example, the specified period K may be longer than the necessary period. In this case, the water pressure WP can be changed from the second value WP2to the first value WP1before the first start time V1A. Thus, the second injection process allows the water pressure WP to be kept at the second value WP2until the end time of the second injection process. Further, the first injection process allows the water pressure WP to be kept at the first value WP1until the start time of the first injection process. When the specified period K is longer than the necessary period, the water pressure WP may be changed at any point in time of the specified period K. For example, the open degree D of the adjustment valve76may be changed subsequent to a predetermined period from the second end time V2B. Further, the timing of changing the open degree D of the adjustment valve76may be calculated based on the running state of the internal combustion engine10. The specified period K does not have to be used. Further, the second injection process and the first injection process may be executed continuously. In this case, for example, the water pressure WP may start to be lowered during the second injection process so that the water pressure WP has a value suitable for the first injection process at the start time of the first injection process. The water pressure WP in at least part of the period during the execution of the second injection process only needs to be higher than the water pressure WP in at least part of the period during the execution of the first injection process. This configuration prevents the formation of a relatively large water droplet during part of at least the period. The first start time V1A is not limited to the example in the above embodiment. Instead, the first start time V1A may be subsequent to the valve-opening time TS of the intake valve23. For example, when the target injection amount Qs is sufficiently smaller than the allowable injection amount Qv, the first start time V1A may be subsequent to the valve-opening time TS of the intake valve23. This allows the water injection valve14to fully supply the target injection amount Qs of water during the valve-open period U2of the intake valve23. The configuration of the water supply mechanism70is not limited to the example in the above embodiment. The water supply mechanism70only needs to be configured to correctly adjust the water pressure WP for the water injection valve14. For example, instead of arranging each return passage79on a corresponding branch passage75as in the above embodiment, the water supply mechanism70may include only one return passage. In addition, the water supply mechanism70may include only one adjustment valve76. In this case, in the same manner as the above embodiment, the pump77is located in the supply passage74that extends from the tank78, and each branch passage75branches from the supply passage74. Further, the return passage connects the tank78to the portion of the supply passage74downstream of the pump77and upstream of the portions branched into the branch passages75. Furthermore, the adjustment valve76is located in the return passage. In this case, the pressure of water flowing downstream of the pump77in the supply passage74changes depending on the open degree D of the adjustment valve76. This changes the water pressures WP for all the water injection valves14. In such a manner, a common adjustment valve may be disposed on all the water injection valves14, and this adjustment valve may be used to collectively change the water pressures WP for all the water injection valves14. This configuration may be employed if it is already clear that the period for executing the first injection process for a specific cylinder11does not overlap the period for executing the second injection process for another cylinder11because of, for example, the setting of the target injection amount Qs in the target water amount map M1. The pump77does not have to be driven by an electric motor. The pump77may be driven by, for example, the crankshaft18. In this case, the open degree D of the adjustment valve76only needs to be adjusted in correspondence with a driven state of the pump77to obtain a correct water pressure WP. Each adjustment valve76does not need to have the configuration of the above embodiment. The adjustment valve76only needs to change the water pressure WP. The adjustment valve76may be, for example, a ball valve. The pressure adjustment device is not limited to the example in the above embodiment. For example, the pressure adjustment device may change the water pressure WP by changing the discharge amount of the pump77and the open degree D of each adjustment valve76. In this case, the pressure adjustment device includes the pump77and the adjustment valves76. Instead, the pressure adjustment device may change the water pressure WP by changing only the discharge amount of the pump77. In this case, the pressure adjustment device includes the pump77. The pressure adjustment device is not limited to a pump or a valve. The pressure adjustment device only needs to correctly change the water pressure WP. Based on the configuration of the pressure adjustment device that is to be controlled, the controller100needs to control the pressure adjustment device. Depending on the configuration of the pressure adjustment device, the controller100may refer to the detection value of the water pressure sensor30and perform feedback control on the pressure adjustment device such that a correct water pressure WP is obtained. The reach period L is not limited to a fixed value and may be changed depending on, for example, the amount GA of intake air. The reach period L may be 0. In this case, most of the target injection amount Qs of water reaches the inside of each cylinder11. The content of the target water amount map M1is not limited to the example in the above embodiment. The target water amount map M1only needs to be set depending on the engine running state to inject water needed to cool the inside of the cylinder11by a necessary amount. The method for obtaining the crank position Scr at which the intake valve23reaches the valve-opening time TS is not limited to the example in the above embodiment. For example, detection values of the crank position sensor34and the intake cam position sensor36may be used to obtain the crank position Scr at which the intake valve23reaches the valve-opening time TS. If the crank position Scr at which the intake valve23reaches the valve-opening time TS can be correctly obtained, any method may be employed. The same applies to the crank position Scr at which the intake valve23reaches the valve-closing time TC. The overall configuration of the internal combustion engine10is not limited to the example of the above embodiment. For example, the number of the cylinders11may be changed. The internal combustion engine10only needs to include the water injection valves14, the intake valve23, and the pressure adjustment device. The number of the water injection valves14in each cylinder11is not limited to the example of the above embodiment. For example, as shown inFIG.6, one cylinder11may include two water injection valves14. The two water injection valves14may inject water into the cylinder11through the intake port12A. The two water injection valves14are hereinafter referred to as a first water injection valve14A and a second water injection valve14B. When one cylinder11includes the first water injection valve14A and the second water injection valve14B, the following configuration may be employed. A water supply mechanism70A is used such that each of the first water injection valve14A and the second water injection valve14B is supplied with water with a different water pressure WP. Specifically, the first water injection valve14A is connected to a first passage171that extends from the tank78, and the second water injection valve14B is connected to a second passage172that extends from the tank78. For example, a first pump is disposed in the first passage171as a first pressure adjustment device191, and a second pump is disposed in the second passage172as a second pressure adjustment device192. The controller100controls driving of the first pump such that the water pressure WP of the water supplied to the first water injection valve14A has the first value WP1. Further, the controller100controls driving of the second pump such that the water pressure WP of the water supplied to the second water injection valve14B has the second value WP2, which is greater than the first value WP1. The controller100uses the first water injection valve14A as a water injection valve14dedicated for the first injection process and uses the second water injection valve14B as a water injection valve14dedicated for the second injection process. Unlike the configuration of the above embodiment, in which the first and second injection processes are executed using a common water injection valve14, the configuration of this modification eliminates the need for the pressure adjustment device to change the water pressure WP depending on the execution of each injection process. Thus, even if the specified period K for changing the water pressure WP is not provided, a different injection pressure can be used for each of the entire period during which the second injection process is executed and the entire period during which the first injection process is executed. That is, this configuration allows the second injection process and the first injection process to be executed continuously while also using a different injection pressure in the entire period of each of the two injection processes. WhileFIG.6shows only one of the cylinders11, the first water injection valve14A and the second water injection valve14B are disposed on another cylinder11in the same manner. The first water injection valve14A corresponding to a further cylinder11is connected to a first branch passage181branched ing pefrom a portion of the first passage171downstream of the first pressure adjustment device191. The second water injection valve14B corresponding to yet another cylinder11is connected to a second branch passage182branched from a portion of the second passage172downstream of the second pressure adjustment device192. In a case in which each cylinder11includes multiple water injection valves14, the configuration of the water supply mechanism is not limited to the example ofFIG.6. The water supply mechanism only needs to supply each water injection valve14with the water having a correct water pressure WP. The overall configuration of the vehicle300is not limited to the example of the above embodiment. For example, the vehicle300may include a motor generator as the driving source of the vehicle300, in addition to the internal combustion engine10. The amount of water injected from the water injection valves14in the first injection process and the amount of water injected from the water injection valves14in the second injection process are not limited to the examples of the above embodiment. For example, when the allowable injection amount Qv is less than the target injection amount Qs, the amount of water injected from the water injection valves14in the first injection process may be less than the allowable injection amount Qv. In this case, the set injection amount Qr by which water is injected from the water injection valves14in the second injection process may be increased accordingly. In the comparison between the second injection process in a specific combustion cycle and the first injection process in a different combustion cycle, the use of a different water pressure WP in each of the injection processes is effective for preventing the formation of a relatively large water droplet. In this regard, for example, the following configuration may be employed. In the specific combustion cycle, only the second one of the first and second injection processes is executed. Then, the water pressure WP in the second injection process is set to be higher than the water pressure WP in the first injection process of the different combustion cycle. Various changes in form and details may be made to the examples above without departing from the spirit and scope of the claims and their equivalents. The examples are for the sake of description only, and not for purposes of limitation. Descriptions of features in each example are to be considered as being applicable to similar features or aspects in other examples. Suitable results may be achieved if sequences are performed in a different order, and/or if components in a described system, architecture, device, or circuit are combined differently, and/or replaced or supplemented by other components or their equivalents. The scope of the disclosure is not defined by the detailed description, but by the claims and their equivalents. All variations within the scope of the claims and their equivalents are included in the disclosure. | 76,023 |
11859582 | MODES FOR CARRYING OUT THE INVENTION A detailed description will hereinafter be made on an embodiment of the present disclosure with reference to the drawings. The following description on the preferred embodiment is essentially and merely illustrative and thus has no intention to limit the present disclosure, application subjects thereof, and application thereof at all. FIG.1is a plan view in which a front portion of a vehicle1including an intake sound amplifier20, which will be described below, is seen from above. As illustrated inFIG.1, an engine3is mounted in an engine compartment2in the front portion of the vehicle1. The engine3is a vertically-mounted multicylinder engine in which a plurality of cylinders (not illustrated) are aligned in a vehicle front-rear direction (an up-down direction inFIG.1). Although not illustrated, a reduction drive is coupled to the engine3in the engine compartment2. In addition, although not illustrated, a supercharger, a motor, a battery, and the like are also accommodated in the engine compartment2. The engine compartment2is divided by a front crossmember4that extends in a vehicle width direction (a right-left direction inFIG.1) on a vehicle front side, right and left side frames (front side members)5that extend in the vehicle front-rear direction on both sides in the vehicle width direction, and a dashboard6that extends in the vehicle width direction on a vehicle rear side of the front crossmember4.FIG.1only illustrates the side frame5on the left side in the vehicle width direction when seen in a vehicle advancing direction. The front crossmember4and the dashboard6separate the inside of the engine compartment2from the outside in the vehicle front-rear direction. In particular, the dashboard6separates the engine compartment2from a cabin7. The side frame5separates the inside of the engine compartment2from the outside in the vehicle width direction. The side frame5is made of a steel material such as channel steel, H-steel, or square tube steel. The side frame5extends in the vehicle front-rear direction from an end portion in the vehicle width direction of the front crossmember4to the vicinity of the dashboard6. A plate8is attached to a surface on an inner side in the vehicle width direction of an end portion on the vehicle rear side of the side frame5. The plate8is arranged such that a thickness direction thereof matches the vehicle width direction. In the vehicle front-rear direction, the plate8is arranged between the side frame5and the dashboard6. The side frame5and the plate8are located at substantially the same position in the vehicle width direction. A fender panel9(indicated by a two-dot chain line inFIG.1) is provided outward in the vehicle width direction of the side frame5. The fender panel9covers a wheel (in detail, a front wheel, which is not illustrated) to protect an occupant and a pedestrian from the rotating wheel itself or a stone, mud, water, or the like hitting or splashing up by the wheel. The fender panel9is also an outer panel that is arranged in an outer end portion in the vehicle width direction of the vehicle1. In the vehicle width direction, a clearance (space) is provided between the side frame5and the fender panel9. The engine3includes an intake passage10through which intake air (fresh air) is introduced into the engine3. The intake passage10includes an intake duct11that suctions the intake air; an air cleaner12that filters the intake air, a throttle valve13that regulates an intake amount, an intake manifold14, from which the intake air is introduced into each of the cylinders in the engine3, and an intake pipe15through which the intake air flows from the intake duct11to the intake manifold14. The intake passage10is located inward in the vehicle width direction of the side frame5. Although not illustrated, an exhaust passage is connected to the engine3. The engine3includes the intake sound amplifier20. The intake sound amplifier20amplifies intake sound that is transmitted from the engine3mounted in the engine compartment2to the cabin7. The intake sound amplifier20includes a first passage30, a device body40, and a second passage50. The first passage30is branched from the intake passage10. The device body40is connected to a downstream side of the first passage30. The second passage50is connected to a downstream side of the device body40. The first passage30is tubular and made of the resin. The first passage30is branched from a branch section16, which is located between the air cleaner12and the throttle valve13, in the intake pipe15. The first passage30extends from the branch section16to the outer side in the vehicle width direction of the side frame5through a lower side of the side frame5, and then further extends to the rear of the vehicle. Here, although a detailed description will be made below, the device body40is located outward in the vehicle width direction of the side frame5. That is, the first passage30is connected to the device body40through the lower side of the side frame5. In addition, a downstream end portion31of the first passage30is located outward in the vehicle width direction of the side frame5. FIG.2is a side view in which the intake sound amplifier20is seen from the left side.FIG.3is a vertical cross-sectional view of the intake sound amplifier20. As illustrated inFIGS.2and3, the downstream end portion31of the first passage30is inclined in a manner to extend upward as extending to the vehicle rear side (the downstream side). A flange32is provided to an opening edge in the downstream end portion31of the first passage30. As illustrated inFIG.1, as described above, the device body40is located outward in the vehicle width direction of the side frame5. In addition, the device body40is located inward in the vehicle width direction of the fender panel9. That is, the device body40is located between the side frame5and the fender panel9in the vehicle width direction. The device body40is connected to the downstream end portion31(downstream side) of the first passage30. As illustrated inFIG.2, a part of the device body40is located at an overlapping position with the side frame5when seen in the vehicle width direction. In other words, the device body40is located at the same height as the side frame5. As illustrated inFIG.3, the device body40has a housing41, a vibration body (resonator)42, and an attachment section43. The housing41has a bottomed cylindrical shape that is opened to the vehicle front side (upstream side). A flange41ais provided to an opening edge on the vehicle front side of the housing41. The housing41and the downstream end portion31of the first passage30are mutually connected by the flanges32,41a. An opening41cis provided to a bottom wall section41bon the vehicle rear side (downstream side) of the housing41. The cylindrical housing41extends horizontally in the vehicle front-rear direction. The housing41is made of the resin. The vibration body42has a bottomed cylindrical shape that is opened to the vehicle front side (upstream side), and is accommodated in the housing41. The vibration body42includes a cylindrical section42a, a bottom wall section42b, and a flange42c. The vibration body42is made of rubber. The vibration body42is formed in a membrane shape. Similar to the housing41, the cylindrical section42aextends horizontally in the vehicle front-rear direction. The cylindrical section42ais formed in an elastically deformable accordion shape. The bottom wall section42bcovers an opening on the vehicle rear side of the cylindrical section42a. The bottom wall section42bfaces the opening in the downstream end portion31of the first passage30. The flange42cis provided to an opening edge on the vehicle front side of the cylindrical section42a. The flange42cis fitted to a recessed section41dthat is provided to the flange41aof the housing41. In this way, the vibration body42is fixed to the housing41. Since the cylindrical section42ais formed in the accordion shape, the bottom wall section42bof the vibration body42vibrates (membrane-vibrates) by pulsation (a pressure wave) of the intake air that is branched from the intake passage10and flows into the device body40via the first passage30. Since the vibration body42vibrates by the pulsation of the intake air, the intake sound is resonated and amplified in a particular frequency band. The attachment section43is fixed to an outer peripheral portion of the housing41. Since the attachment section43is fixed to a lower surface of the side frame5, the body device40is attached to the side frame5. The second passage50has a tubular shape and is made of the resin. As illustrated inFIGS.2and3, an upstream end portion51of the second passage50is connected to the opening41cof the housing41in the device body40. That is, the upstream end portion51of the second passage50is located outward in the vehicle width direction of the side frame5. Similar to the downstream end portion31of the first passage30, the upstream end portion51of the second passage50is inclined in the manner to extend upward as extending to the vehicle rear side (downstream side). The upstream end portion51of the second passage50may integrally formed with the housing41of the device body40. As illustrated inFIGS.1and2, the second passage50extends from the opening41cof the housing41to the vehicle rear side, that is, the cabin7side. In detail, the second passage50extends from the opening41cof the housing41to the vehicle rear side and the upper side, is then bent, and extends to the vehicle rear side and the lower side. Thereafter, the second passage50is further bent, extends to the inner side in the vehicle width direction, and is then bent to the vehicle rear side. That is, an opening in a downstream end portion52of the second passage50faces the cabin7. In addition, the opening in the downstream end portion52of second passage50is located near the dashboard6. Although a detailed description will be made below, the downstream end portion52of the second passage50is located inward in the vehicle width direction of the side frame5. As illustrated inFIG.1, the second passage50includes an outer portion53and an inner portion54. The outer portion53is arranged outward in the vehicle width direction of the plate8. The inner portion54is arranged inward in the vehicle width direction of the plate8. Here, as described above, the side frame5and the plate8are located at substantially the same position in the vehicle width direction. Accordingly, in other words, the outer portion53is arranged outward in the vehicle width direction of the side frame5. The inner portion54is arranged inward in the vehicle width direction of the side frame5. In the second passage50, the outer portion53and the inner portion54are made of mutually different members as being separated by the plate8. In order to communicate the outer portion53and the inner portion54with each other, the plate8is provided with a hole (not illustrated). The upstream end portion51is included in the outer portion53. The downstream end portion52is included in the inner portion54. In the second passage50, a passage length of the outer portion53is longer than a passage length of the inner portion54. As it has been described so far, according to this embodiment, the device body40of the intake sound amplifier20is arranged outward in the vehicle width direction of the side frame5. Thus, radiant heat from the engine3is blocked by the side frame5and is less likely to be transferred to the vibration body42included in the device body40. In this way, it is possible to suppress a change in an amplification frequency of the intake sound, which is caused by an influence of the radiant heat (radiation heat) from the engine3. In detail, it is possible to suppress the change in the amplification frequency of the intake sound by suppressing modification of the rubber vibration body42and modification of the resinous first passage30and the resinous second passage50, which are caused by the radiant heat from the engine3. In addition, the device body40of the intake sound amplifier20is arranged outward in the vehicle width direction of the side frame5, that is, on the outside of the engine compartment2. Thus, a size of the intake sound amplifier20(a size of the device body40, lengths and thicknesses of the first passage30and the second passage50, and the like), which relates to performance of the intake sound amplifier20, can be designed relatively freely without considering interference with various types of equipment (for example, intake/exhaust systems, the reduction drive, and the like) arranged in the engine compartment2. As it has been described so far, in regard to the intake sound amplifier20, it is possible to suppress the change in the amplification frequency of the intake sound, which is caused by the radiant heat from the engine3, and to increase the degree of freedom in layout thereof. Since the device body40of the intake sound amplifier20is located at the overlapping position with the side frame5when seen in the vehicle width direction, which is further advantageous for suppressing the change in the amplification frequency of the intake sound, which is caused by the radiant heat from the engine3. Apart of the first passage30, more specifically, the downstream end portion31thereof is located outward in the vehicle width direction of the side frame5. In this way, the first passage30can be protected from the radiant heat of the engine3, which is further advantageous for suppressing the change in the amplification frequency of the intake sound. In addition, it is possible to increase the degree of freedom in layout of the first passage30. Since the first passage30is connected to the device body40through the lower side of the side frame5, it is possible to further increase the degree of freedom in layout of the first passage30by effectively using a space under the side frame5. The passage length of the outer portion53in the second passage50is longer than the passage length of the inner portion54thereof. Thus, it is possible to further increase the degree of freedom in layout of the second passage50by arranging a large portion of the second passage50outward in the vehicle width direction of the side frame5. The device body40is located inward in the vehicle width direction of the fender panel9. Thus, a dead space between the side frame5and the fender panel9(inside of a fender) can effectively be used to arrange the intake sound amplifier20therein. The present disclosure has been described so far in terms of the preferred embodiment. However, such descriptions are not limiting matters, and various modifications can be made thereto. A part of the device body40of the intake sound amplifier20may be located directly under the side frame5. That is, at least a part of the device body40only needs to be located outward in the vehicle width direction of the side frame5. At a location inward in the vehicle width direction of the side frame5, the first passage30may be connected to the device body40. The first passage30may be connected to the device body40through the upper side of the side frame5. A device such as a sound deadening device may be provided in the middle of the second passage50. The plate8may not be provided. INDUSTRIAL APPLICABILITY The present disclosure can be applied to the engine intake sound amplifier. Thus, the present disclosure is extremely useful and has high industrial applicability. It should be understood that the embodiments herein are illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof, are therefore intended to be embraced by the claims. DESCRIPTION OF REFERENCE CHARACTERS 1Vehicle2Engine compartment3Engine5Side frame6Dashboard7Cabin8Plate9Fender panel10Intake passage20Intake sound amplifier30First passage40Device body41Housing42Vibration body50Second passage53Outer portion54Inner portion | 16,150 |
11859583 | DETAILED DESCRIPTION FIG.1illustrates an exemplary embodiment of power system10configured to combust a mixture of fuel and air to generate mechanical power. Power system10may include engine12. Engine12may be a four-stroke diesel engine. It is contemplated, however, that engine12may be any other type of internal combustion engine such as, for example, a two-stroke diesel engine, a gaseous-fuel powered two-stroke engine, a gaseous-fuel powered four-stroke engine, a dual-fuel powered two-stroke or four-stroke engine, or a two-stroke or four-stroke gasoline engine. It is also contemplated that engine12may be a spark-ignition engine. Engine12may include an engine block14that at least partially defines a plurality of cylinders16. As illustrated inFIG.1, exemplary engine12may include four cylinders16. It is contemplated, however, that engine12may include any number of cylinders16. Moreover, cylinders16in engine12may be disposed in an “in-line” configuration, a “V” configuration, an opposing-piston configuration, or in any other suitable configuration. Engine12may include crankshaft18rotatably disposed within engine block14. Connecting rods (not shown) may connect a plurality of pistons (not shown) to crankshaft18, so that combustion within the one or more cylinders16results in a sliding motion of each piston within a respective cylinder16, which, in turn, results in rotation of crankshaft18, as is conventional in a reciprocating-piston engine. Power system10may include a fuel system20configured to deliver pressurized fuel into corresponding combustion chambers of each cylinder16according to a timing scheme, resulting in coordinated combustion within cylinders16to produce mechanical power. For example, fuel system20may be a high-pressure common rail system and may include source22configured to hold a supply of fuel, and fuel pump24configured pressurize the fuel from source22and direct the fuel to a plurality of fuel injectors26associated with cylinders16via common rail28. While fuel system20is described as a common rail system, it is contemplated that other fuel system configurations may be possible. For example, fuel system20may include dedicated fuel lines that supply fuel directly from source22to fuel injectors26. Fuel system20may also include controller30, crank angle sensor32, and one or more temperature sensors34. Controller30may be configured to control an operation of fuel system20based at least partially on inputs received from crank angle sensor32and/or temperature sensors34. Controller30may embody a single or multiple microprocessors, digital signal processors (DSPs), etc. Numerous commercially available microprocessors can be configured to perform the functions of controller30. Various other known circuits may be associated with controller30including power supply circuitry, signal-conditioning circuitry, and communication circuitry. Controller30may also be associated with one or more non-transitory storage devices, for example, memory devices, Random Access Memory (RAM) devices, NOR or NAND flash memory devices, and Read Only Memory (ROM) devices, CD-ROMs, hard disks, floppy drives, optical media, solid state storage media, etc. Crank angle sensor32may be located on crankshaft18or on engine block14. Crank angle sensor32may be a Hall Effect sensor, an optical sensor, a magnetic sensor, or any other type of crank angle sensor known in the art. Crank angle sensor32may be configured to send signals indicative of crank angle θ, which may be an angle of rotation of crankshaft18relative to a top dead center (TDC) position of a piston in cylinder16. One of ordinary skill in the art would recognize that as is conventionally known, prior to reaching the TDC position, the piston moves from adjacent crankshaft18towards a head end of cylinder16, whereas after reaching the TDC position, the piston in a conventional engine moves away from the head end of cylinder16towards crankshaft18. In one exemplary embodiment, crank angle sensor32may also be configured to send signals indicative of a rotational speed of crankshaft18. Temperature sensor34may be disposed on cylinder16and may be configured to determine a temperature within cylinder16. Temperature sensor34may include diode thermometers, thermistors, thermocouples, infrared sensors, or any other types of temperature sensors known in the art. Controller30may be in communication with fuel injectors26, crank angle sensor32, and temperature sensors34, and may control operations of fuel system20based on the signals from one or more of fuel injectors26, crank angle sensor32, and temperature sensors34. It is contemplated that fuel system20may include other types of sensors, for example, NOx sensors, air and fuel flow rate sensors, pressure sensors, speed sensors, torque sensors, acceleration sensors, etc. It is also contemplated that fuel system20may include other conventional components such as filters, check valves, relief valves, etc. FIG.2illustrates a cross-sectional view of an exemplary fuel injector26. Fuel injector26may include fuel injector body36, which may extend from adjacent fuel inlet end38to adjacent fuel discharge end40. Fuel injector body36may be disposed about longitudinal axis42of fuel injector26. Fuel inlet end38may be disposed outside cylinder16, whereas fuel discharge end40may be disposed within cylinder16. Fuel injector body36may include upper body44and lower body46. Upper body44may include injector bore48, which may extend from adjacent fuel inlet end38to adjacent fuel discharge end40. In one exemplary embodiment as illustrated inFIG.2, lower body46may be disposed adjacent fuel discharge end40and may project outward from upper body44through injector bore48. Lower body46may include lower body bore50, which may extend across a length of lower body46. It is contemplated, however, that in some exemplary embodiments, upper body44and lower body46may form an integral unitary injector body32. Fuel injector26may include control portion60and delivery portion62. Control portion60may be disposed within injector bore48. Delivery portion62may be disposed partially within injector bore48and partially within lower body bore50. Control portion60may extend from fuel inlet end38to control portion end64disposed between fuel inlet end38and fuel discharge end40. Delivery portion62of fuel injector26may extend from control portion end64to adjacent fuel discharge end40. Fuel injector26may include fuel inlet66and drain outlet68. Fuel inlet66may be connected to common rail28and may be configured to receive pressurized fuel from common rail28. Drain outlet68may be connected to source22via a passageway (not shown). Drain outlet68may be configured to allow excess fuel to be returned to source22. One of ordinary skill in the art would recognize that a pressure in common rail28and at fuel inlet68may be higher than a pressure at drain outlet68and in source22. Delivery portion62may include check valve member70, check valve member72, control chamber74, control chamber76, passageways78and80, and one or more orifices82. Check valve member70may extend from adjacent base end84to injection end86. Base end84may be disposed adjacent control portion end64, and injection end86may be disposed adjacent fuel discharge end40. Check valve member70may be concentrically disposed about longitudinal axis42. Check valve member70may be configured to move along its lengthwise direction along longitudinal axis42. In one exemplary embodiment as illustrated inFIG.2, check valve member70may be in the form of an elongated needle. Control chamber74may be disposed adjacent base end84of check valve member70. Control chamber74may be connectable with drain outlet68via a passageway (not shown). Check valve member72may extend from base end88to injection end90. Base end88may be disposed between base end84and fuel discharge end40, and injection end90may be disposed adjacent fuel discharge end40. In one exemplary embodiment as illustrated inFIG.2, check valve member72may be in the form of an elongated needle. Control chamber76may be disposed adjacent base end88of check valve member72. Control chamber76may be connectable with drain outlet68via passageways78and80. The dimensions of passageways78and80may be selected to control a rate at which fuel may be allowed to drain from control chamber76to drain outlet68. FIG.3illustrates a magnified view of delivery portion62of fuel injector26. As illustrated inFIG.3, check valve member72may include bore92extending from base end88to adjacent injection end90. Check valve member70may be disposed within bore92of check valve member72. In one exemplary embodiment as illustrated inFIG.3, check valve member70may be disposed concentrically with bore92. Check valve member70may be separated from bore92of check valve member72by clearance94. In some exemplary embodiments, clearance94may be termed “M orifice.” As also illustrated inFIG.3, delivery portion62may include sac96and upper nozzle space98. Sac96may be disposed between injection end86of check valve member70and injector body32and may be configured to hold pressurized fuel received from fuel inlet66. Orifice82may be configured to fluidly connect sac96with cylinder16. Upper nozzle space98and clearance94may define nozzle chamber100. As illustrated inFIG.3, check valve member70may be disposed within nozzle chamber100. Nozzle chamber100may be connected with fuel inlet66via one or more passageways (not shown) in injector body32. Nozzle chamber100may deliver fuel from fuel inlet66to sac96. Check valve member70may be configured to move from a closed position to an open position. In its closed position, check valve member70may sealingly be in contact with nozzle seat102in injector body32so as to block a flow of fuel from fuel inlet66to sac96to the one or more orifices82. In its open position, check valve member70may be out of contact with nozzle seat102allowing the flow of fuel to sac96and the one or more orifices82. Connecting nozzle chamber100to fuel inlet66may expose injection end86of check valve member70to high pressure from common rail28. As discussed above, control chamber74(seeFIG.2) may be connectable to drain outlet68, which may have a relatively low pressure compared to the pressure in common rail28. Thus, when control chamber74is connected to drain outlet68, check valve member70may be subjected to a pressure difference, with a high pressure corresponding to the pressure in common rail28acting on injection end86, and a low pressure of source22acting on base end84through control chamber74. As a result of this pressure difference, check valve member70may move from its closed position to its open position along longitudinal axis42in a direction from injection end86towards base end84. In is open position, when check valve member70is out of contact with nozzle seat102, check valve member70may permit a flow of fuel to sac96and the one or more orifices82into cylinder16. Thus, moving check valve member70from its closed position to its open position may allow a first flow of fuel from fuel inlet66through nozzle chamber100to the one or more orifices82and to cylinder16. A fuel flow rate or an amount of fuel flow through the one or more orifices82, caused by operation of check valve member70, may be determined at least in part based on the geometrical dimensions of clearance94between check valve member70and bore92. In one exemplary embodiment, clearance94may be generally uniform along a length of check valve member70and bore92from adjacent base end88to adjacent injection end90. In another exemplary embodiment, clearance94may vary along the length of check valve member70and bore92. In yet another exemplary embodiment, a dimension of clearance94adjacent base end88may be larger relative to a dimension of clearance94adjacent injection end90. In other exemplary embodiments, the dimension of clearance94adjacent injection end90may be larger than the dimension of clearance94adjacent base end88. It is also contemplated that in some exemplary embodiments, a dimension of clearance94may be larger at a location between base end88and injection end90. Check valve member72may be disposed within lower body bore50of lower body46. Check valve member72may be radially spaced apart from lower body bore50. A space between check valve member72and lower body bore50may define nozzle chamber106. Nozzle chamber106may be connected to fuel inlet66via one or more passageways (not shown) within injector body32. Check valve member72may be configured to move from a closed position to an open position. In its closed position, check valve member72may sealingly be in contact with nozzle seat108in injector body32so as to block flow of fluid from fuel inlet66and nozzle chamber106to sac96. In its open position, check valve member72may be out of contact with nozzle seat108, allowing fuel to flow from nozzle chamber106to sac96. As discussed above, nozzle chamber106may be connected to fuel inlet66, which may expose injection end90of check valve member72to high pressure from common rail28. As also discussed above, control chamber76may be connectable to drain outlet68, which may have a relatively low pressure compared to the pressure in common rail28. Thus, when control chamber76is connected to drain outlet68, check valve member72may be subjected to a pressure difference, with a high pressure corresponding to the pressure in common rail28acting on injection end90, and a low pressure of source22acting on base end88through control chamber76. As a result of this pressure difference, check valve member72may move from its closed position to its open position along longitudinal axis42in a direction from injection end90towards base end88. In its open position, when check valve member72is out of contact with nozzle seat108, check valve member72may permit a flow of fuel from nozzle chamber106to sac96, which flow of fuel may be injected into cylinder16through the one or more orifices82. Thus, moving check valve member72from its closed position to its open position may allow a second flow of fuel from fuel inlet66through nozzle chamber106to the one or more orifices82and to cylinder16. Further, moving check valve member72from its closed position to its open position may also allow high pressure from common rail28to be applied to check valve member70adjacent nozzle seat102by allowing fuel to flow from fuel inlet66to flow through nozzle chamber106to nozzle chamber110. Thus, the pressure applied to check valve member70may be altered by operation of check valve member72. A fuel flow rate or an amount of fuel flow through the one or more orifices82, caused by operation of check valve member72may be determined at least in part based on a gap (not shown) between check valve member72and nozzle seat108. One of ordinary skill in the art would recognize that when both check valve member70and check valve member72are in their respective open positions, fuel may flow into sac96from both nozzle chamber100and nozzle chamber106. Thus, opening both check valve member70and check valve member72may allow a second amount of fuel to flow out of orifices82into cylinder16as compared to a first amount of fuel that may flow through orifices82into cylinder16when only check valve member70may be in an open position with check valve member72remaining in its closed position. Returning toFIG.2, control portion60may include passageway110, passageway112, and control valve assembly114. Passageway110may be disposed within fuel injector body36and may be configured to deliver pressurized fuel from fuel inlet66to nozzle chamber100and nozzle chamber106in delivery portion62of fuel injector26. It is contemplated that control portion60and/or delivery portion62may include additional passageways (not shown) that may connect passageway110with nozzle chamber100and nozzle chamber106. In some exemplary embodiments, additional passageways (not shown) in control portion60and/or delivery portion62may connect passageway110and fuel inlet66to one or both of control chambers74and76. Passageway112may be disposed within fuel injector body36and may be configured to connect control chambers74and76in delivery portion62of fuel injector26with source22via drain outlet68. For example, as illustrated inFIG.2, passageway112may connect passageways78and80to drain outlet68. Although only two passageways110and112are illustrated in fuel injector body36, it is contemplated that fuel injector may include more than one passageway110connecting the fuel inlet with nozzle chambers100and106and more than one passageway112connecting control chambers74and/or76with drain outlet68. Control valve assembly114may include control valve116, control valve118, solenoid120, and solenoid122. In one exemplary embodiment, control valves116and118may be two-way or three-way solenoid control valves. It is also contemplated, however, that control valves116and118may be controlled via arrangements other than a solenoid. For example, in some exemplary embodiments, control valves116and118may be controlled via camming arrangements or through the use of biasing members such as springs. In one exemplary embodiment as illustrated inFIG.2, control valve116may be positioned in injector body32adjacent control portion end64, and between fuel inlet end38and control portion end64. Control valve116may be movable along longitudinal axis42between a first position in which control chamber74is fluidly blocked from drain outlet68, and a second position in which control chamber74is fluidly connected to drain outlet68. As illustrated inFIG.2, control valve116may be biased by biasing member124towards its first position. In one exemplary embodiment as illustrated inFIG.2, biasing member124may be in the form of a spiral spring, although other shapes are also contemplated. Solenoid120may be disposed adjacent control portion end64. Solenoid120may be operable to move control valve116against a biasing force of biasing member124such that control chamber74may be connected to drain outlet68via one or more passageways (not shown) in injector body32. Thus, by operation of solenoid120, control chamber74associated with check valve member70may be connected to or blocked from drain outlet68. Control valve118may be positioned in injector body32adjacent fuel inlet end38, and between fuel inlet end38and control valve116. Control valve118may be movable along longitudinal axis42between a first position in which passageway112associated with check valve member72is fluidly blocked from drain outlet68, and a second position in which passageway112is fluidly connected to drain outlet68. Control valve118may be biased by biasing member124towards its first position. In one exemplary embodiment as illustrated inFIG.2, biasing member124may be disposed between control valve116and control valve118. It is contemplated, however, that control valves116and118may each have its own separate biasing member124. Solenoid122may be disposed adjacent control valve118. Solenoid122may be operable to move control valve118against a biasing force of biasing member124such that passageway112may be connected to drain outlet68. Thus, by operation of solenoid122, control chamber76associated with check valve member72may be connected to or blocked from drain outlet68via passageways78,80, and112. Although control valve116and solenoid120have been described above as being positioned adjacent control portion end64, it is contemplated that control valve116and solenoid120may instead be positioned adjacent fuel inlet end38or elsewhere in injector body36. Likewise, although control valve118and solenoid122have been described above as being positioned adjacent fuel inlet end38, it is contemplated that control valve118and solenoid122may instead be positioned adjacent control portion end64or elsewhere in injector body36. As discussed above, in some exemplary embodiments, control chambers74and76may also be connected to fuel inlet66. One of ordinary skill in the art would recognize, however, that even when control chamber74is connected to fuel inlet66, when control chamber74is also connected to drain outlet68, the fluid connection to drain outlet68may be sufficient to reduce a pressure in control chamber74, causing check valve member70to move to its open position. Likewise, one of ordinary skill in the art would recognize that even when control chamber76is connected to fuel inlet66, when control chamber76is also connected to drain outlet68, the fluid connection to drain outlet68may be sufficient to reduce a pressure in control chamber76, causing check valve member72to move to its open position. FIG.4illustrates a cross-sectional view of an exemplary fuel injector128. Many of the features of fuel injector128are similar to corresponding features of fuel injector26. For example, like fuel injector26, fuel injector128may include upper body44and control portion60, including passageways110and112, and control valve assembly114. These and other common features of fuel injectors26and128are labeled inFIG.4using the same numerals as used inFIG.2corresponding to fuel injector26. Furthermore, the above description of the common features in connection withFIG.2applies equally to these features of fuel injector128. Only features of fuel injector128that are different from those of fuel injector26are discussed in detail below. Fuel injector128may include delivery portion132, which may be different from delivery portion62of fuel injector26. Delivery portion132may include lower body130, and may extend from control portion end64to fuel discharge end40. Delivery portion132of fuel injector128may include nozzle portion134, body portion136, and upper portion138. Nozzle portion134may extend from adjacent fuel discharge end40to nozzle portion end140disposed between control portion end64and fuel discharge end40. Body portion136may extend from nozzle portion end140to body portion end142disposed between control portion end64and nozzle portion end140. Upper portion138may extend from control portion end64to body portion end142. Nozzle portion134may include lower body130, nozzle chamber150, nozzle chamber152, and sac154. Lower body130may be disposed within injector bore48and may extend from nozzle portion end140to adjacent fuel discharge end40.FIG.5illustrates a magnified view of nozzle portion134and body portion136of fuel injector128. Nozzle portion134may include nozzle chamber150and nozzle chamber152disposed in lower body130. Nozzle chambers150and152may be disposed adjacent to and diametrically spaced apart from each other. Nozzle chamber150may be in the form of a bore extending from nozzle portion end140to adjacent fuel discharge end40in lower body130. As illustrated inFIG.5, nozzle chamber150may be radially offset relative to longitudinal axis42. Nozzle chamber150may be connected to fuel inlet66. Check valve member156may extend from adjacent base end158to injection end160. Base end158may be disposed adjacent body portion end142, and injection end160may be disposed adjacent fuel discharge end40. At least a portion of check valve member156may be disposed in nozzle chamber150. Check valve member156may be configured to move along its lengthwise direction (e.g. between base end158and injection end160). Nozzle chamber152may be in the form of a bore extending from nozzle portion end140partway into lower body130to nozzle chamber end162disposed between nozzle portion end140and fuel discharge end40. Nozzle chamber152may be connected to fuel inlet66. Passageway164may be disposed within lower body130and may connect nozzle chamber152and nozzle chamber150. In one exemplary embodiment as illustrated inFIG.5, passageway164may be fluidly connected to nozzle chamber152adjacent nozzle chamber end162. Passageway164may also be fluidly connected to nozzle chamber150at nozzle chamber connection166, which may be disposed between nozzle portion end140and injection end160. It is contemplated that in some exemplary embodiments, passageway164may be fluidly connected to nozzle chamber150adjacent nozzle portion end140. Check valve member168may extend from adjacent base end170to adjacent nozzle chamber end162. Base end170may be disposed adjacent body portion end142. A portion of check valve member168may be disposed in nozzle chamber152. Check valve member168may be configured to move along its lengthwise direction (e.g. between base end170and nozzle chamber end162, and vice-versa). Body portion136may include bore172extending from adjacent nozzle portion end140to body portion end142. Bore172may define a volume, which may be connected to fuel inlet66via one or both of passageways174and176. A portion of both check valve members156and168may be disposed within bore172. In one exemplary embodiment as illustrated inFIG.5, check valve member156may be arranged adjacent to and diametrically spaced apart from check valve member168within bore172. Nozzle chambers150and152may be fluidly connected to bore172and may receive pressurized fuel from bore172, which in turn may receive pressurized fuel from fuel inlet66. Although specific passageways, for example, passageways174,176have been described above, it is contemplated that in some exemplary embodiments, injector body36may include other passageways (not shown) that may connect fuel inlet66with bore172. Control chamber178may be associated with check valve member156and may be disposed in body portion136adjacent base end158of check valve member156. Control chamber178may be connectable with drain outlet68via passageway180. Control chamber182may be associated with check valve member168and may be disposed adjacent base end170of check valve member168. Control chamber182may be connectable with drain outlet68via passageway184. Although specific passageways, for example, passageways180,184have been described above, it is contemplated that in some exemplary embodiments, injector body36may include other passageways (not shown) that may connect control chambers178and182with drain outlet68. Check valve member156may be configured to move from a closed position to an open position. In its closed position, check valve member156may sealingly be in contact with nozzle seat186in nozzle chamber150so as to block flow of fuel from nozzle chamber150to sac154and the one or more orifices82. In its open position, check valve member156may be out of contact with nozzle seat186so as to allow the fuel to flow from nozzle chamber150to sac154and the one or more orifices82. Connecting nozzle chamber150to fuel inlet66via, for example, bore172and passageway174may expose injection end160of check valve member156to high pressure from common rail28. As discussed above, control chamber178may be connectable to drain outlet68via, for example, passageway180. Thus, when control chamber178is connected to drain outlet68, check valve member156may be subjected to a pressure difference, with a high pressure corresponding to the pressure in common rail28acting adjacent injection end160, and a low pressure of source22acting on base end158through control chamber178. As a result of this pressure difference, check valve member156may move from its closed position to its open position in a direction from injection end160towards base end158. In its open position, when check valve member156is out of contact with nozzle seat186, check valve member156may permit a flow of fuel through sac154and the one or more orifices82into cylinder16. Thus, moving check valve member156from its closed position to its open position may allow a first flow of fuel from fuel inlet66through nozzle chamber150to the one or more orifices82and to cylinder16. A fuel flow rate or an amount of fuel flow through nozzle chamber150, caused by operation of check valve member156, may be determined at least in part based on dimensions of clearance188between check valve member156and nozzle chamber150. In one exemplary embodiment, clearance188may be generally uniform along a length of check valve member156from adjacent nozzle portion end140to adjacent nozzle chamber connection166. In another exemplary embodiment, clearance188may vary along the length of check valve member156. In yet another exemplary embodiment, a dimension of clearance188adjacent nozzle portion end140may be larger relative to a dimension of clearance188adjacent nozzle chamber connection166. It is also contemplated that in some exemplary embodiments, a dimension of clearance188may be larger between nozzle portion end140and nozzle chamber connection166as compared to dimensions of clearance188adjacent nozzle portion end140and nozzle chamber connection166. Check valve member168may be configured to move from a closed position to an open position. In its closed position, check valve member168may sealingly be in contact with nozzle seat190in nozzle chamber152so as to block a flow of fuel from nozzle chamber152to nozzle chamber150via passageway164. In its open position, check valve member168may be out of contact with nozzle seat190permitting fuel to flow from nozzle chamber152to nozzle chamber150via passageway164. As discussed above, nozzle chamber152may be connected to fuel inlet66via, for example, passageway176, which may expose nozzle chamber end162to high pressure from common rail28. As also discussed above, control chamber182may be connectable to drain outlet68via, for example, passageway184which may have a relatively low pressure compared to the pressure in common rail28. Thus, when control chamber182is connected to drain outlet68, check valve member168may be subjected to a pressure difference, with a high pressure corresponding to the pressure in common rail28acting adjacent nozzle chamber end162, and a low pressure of source22acting on base end170through control chamber182. As a result of this pressure difference, check valve member168may move from its closed position to its open position in a direction from nozzle chamber end162towards base end170. In its open position, when check valve member168is out of contact with nozzle seat190, check valve member168may permit a flow of fuel from nozzle chamber152to nozzle chamber150via passageway164. Thus, moving check valve member168from its closed position to its open position may allow a second flow of fuel from fuel inlet66through nozzle chamber152to nozzle chamber150and to the one or more orifices82. Further, moving check valve member168from its closed position to its open position may also allow high pressure from common rail28to be applied to check valve member156adjacent nozzle chamber connection166by allowing fuel to flow from fuel inlet66to flow through nozzle chamber152to nozzle chamber150. It is contemplated that in some exemplary embodiments, passageway164may be fluidly connected to control chamber178. In these exemplary embodiments, operation of check valve member168may help adjust a pressure of control chamber178by allowing fuel to flow from fuel inlet66through nozzle chamber152to control chamber178, which in turn may help control movement of check valve member156causing it to be in contact with or out of contact with nozzle seat186. Thus, the pressure applied to check valve member156may be altered by operation of check valve member168. A rate of fuel flow from nozzle chamber152to nozzle chamber150, caused by operation of check valve member168, may be determined at least in part based on a gap (not shown) between check valve member168and nozzle seat190and by the dimensions of passageway164. One of ordinary skill in the art would recognize that when both check valve member156and check valve member168are in their respective open positions, fuel may flow into sac154from both nozzle chamber150and nozzle chamber152. Thus, opening both check valve member156and check valve member168may allow a second amount of fuel to flow out of orifices82into cylinder16as compared to a first amount of fuel that may flow through orifices82into cylinder16when only check valve member156may be in an open position with check valve member168remaining in its closed position. Returning toFIG.4, upper portion138may include passageways194,196, and198, each of which may extend from control portion end64to body portion end142. Passageway194may connect passageways174and176with fuel inlet66via passageway110. Passageway196may connect passageway180with drain outlet68, and passageway198may connect passageway194with drain outlet68via passageway112. Solenoid120may be operable to move control valve116against a biasing force of biasing member124such that passageway180may be connected to drain outlet68. Thus, by operation of solenoid120, control chamber178associated with check valve member156may be connected to drain outlet68. Solenoid122may be operable to move control valve118against a biasing force of biasing member124such that control chamber182may be connected to drain outlet68via passageways112,184, and198. As discussed above, in some exemplary embodiments, control chambers178and182may also be connected to fuel inlet66. One of ordinary skill in the art would recognize, however, that even when control chamber178is connected to fuel inlet66, when control chamber178is also connected to drain outlet68, the fluid connection to drain outlet68may be sufficient to reduce a pressure in control chamber178, causing check valve member156to move to its open position. Likewise, one of ordinary skill in the art would recognize that even when control chamber182is connected to fuel inlet66, when control chamber182is also connected to drain outlet68, the fluid connection to drain outlet68may be sufficient to reduce a pressure in control chamber182, causing check valve member168to move to its open position. INDUSTRIAL APPLICABILITY The fuel system of the present disclosure may be used to continuously adjust the timing of injection, a flow rate or amount of fuel, and a duration of injection of fuel into combustion chambers of an engine during operation of the engine. In particular, the fuel system of the present disclosure may determine a temperature in the one or more cylinders of the engine, and/or an amount of NOx in the exhaust gases produced by the combustion of fuel in the cylinders of the engine. Based on the measured temperature and/or amount of NOx, the fuel system of the present disclosure may control a timing of injection, a rate at which fuel is injected into the cylinders during a combustion cycle, and a duration of injection of fuel into the cylinders. By doing so, the fuel system of the present disclosure may help reduce a temperature in the cylinders, which in turn may help reduce an amount of soot and/or an amount of NOxproduced by the combustion process. An exemplary method of operating fuel injector26or128will be discussed below. FIG.6illustrates an exemplary method600of operation of fuel system20of engine12. The order and arrangement of steps of method600is provided for purposes of illustration. As will be appreciated from this disclosure, modifications may be made to method600by, for example, adding, combining, removing, and/or rearranging the steps of method600. In one exemplary embodiment, method600may be executed by controller30. It is contemplated, however, that fuel injectors26or128may be controlled mechanically via, for example, camming arrangements, or using other techniques for operating control valves116,118, and/or one or more of check valve members70,72,156, or168. Further, method600may be applied to some or all cylinders16of engine12. Method600may include a step of pressurizing fuel (Step602). In one exemplary embodiment, controller30may control fuel pump24to begin drawing fuel from source22and pressurizing the fuel for delivery to engine12. Method600may include a step of supplying pressurized fuel to a fuel injector (Step604). Controller30may control one or more control valves and/or check valves associated with fuel system20to permit a flow of pressurized fuel to flow to fuel inlet66of fuel injector26or128. Method600may include a step of determining a crank angle “θ” (Step606). In one exemplary embodiment, controller30may receive signals from crank angle sensor32. Controller30may rely on correlations, tables, maps, or other algorithms stored in a memory device associated with controller30to determine the crank angle θ relative to a TDC position of a piston in cylinder16associated with fuel injector26or128. Method600may include a step of determining whether crank angle θ is about equal to a crank angle “θ1” (Step608). Crank angle θ1may represent a first threshold value of crank angle θ signifying a beginning of the fuel injection process. When controller30determines that the crank angle θ measured by, for example, crank angle sensor32is less than crank angle θ1(Step608: NO), controller30may return to step606. When controller30determines, however, that the crank angle θ is about equal to crank angle θ1(Step608: YES), controller30may proceed to step610. Method600may include a step of operating a first check valve member (Step610). In step610, controller30may energize solenoid120of fuel injector26or128. Energizing solenoid120may cause control valve116to move from its first position to its second position, overcoming the biasing force exerted by biasing member124. As discussed above, in its second position, control valve116may cause control chamber74of fuel injector26to be fluidly connected to drain outlet68, which may reduce a pressure in control chamber74relative to a pressure of the fuel acting on check valve member70adjacent injection end86. The high pressure adjacent injection end86may cause check valve member70to move along longitudinal axis42out of contact with nozzle seat102, allowing a first flow of fuel to flow out of nozzle chamber100through sac96and the one or more orifices82into cylinder16. Similarly when controller30is configured to control fuel injector128, when control valve116moves to its second position, control valve116may cause control chamber178of fuel injector128to be fluidly connected to drain outlet68, which may reduce a pressure in control chamber178relative to a pressure of the fuel acting on check valve member156adjacent injection end160. The high pressure adjacent injection end160may cause check valve member156to move out of contact with nozzle seat186, allowing a first flow of fuel to flow out of nozzle chamber150through sac154and the one or more orifices82into cylinder16. Method600may include a step of determining whether crank angle θ is greater than or equal to crank angle “θ1” and less than or equal to crank angle “θ2” (Step612). Crank angle θ2may represent a second threshold value of crank angle θ at which an amount of fuel being injected into cylinder16may be changed. In step612, controller30may perform functions similar to those discussed above with respect to, for example, step606to determine the crank angle θ. Controller may compare the determined value of crank angle θ with the threshold values θ1and θ2. When controller30determines that the crank angle θ measured by, for example, crank angle sensor32is greater than or equal to crank angle θ1and less than or equal to crank angle θ2(Step612: YES), controller30may proceed to step614of continuing to operate the first check valve member. In this step, controller30may continue to keep solenoid120energized to allow the first flow of fuel to flow out of orifices82of fuel injector26or128. When controller30determines, however, that the crank angle θ measured by, for example, crank angle sensor32is greater than crank angle θ2(Step612: NO), controller30may proceed to step616. Method600may include a step of operating a second check valve member (Step616). In step616, controller30may energize solenoid122of fuel injector26or128. Energizing solenoid122may cause control valve118to move from its first position to its second position, overcoming the biasing force exerted by biasing member124. As discussed above, in its second position, control valve118may cause control chamber76of fuel injector26to be fluidly connected to drain outlet68, which may reduce a pressure in control chamber76relative to a pressure of the fuel acting on check valve member72adjacent injection end90. The high pressure adjacent injection end90may cause check valve member72to move along longitudinal axis42out of contact with nozzle seat108, allowing a second flow of fuel to flow out of nozzle chamber106and into sac96. The second flow of fuel may also flow out through the one or more orifices82into cylinder16. Similarly when controller30is configured to control fuel injector128, when control valve118moves to its second position, control valve118may cause control chamber182of fuel injector128to be fluidly connected to drain outlet68, which may reduce a pressure in control chamber182relative to a pressure of the fuel acting on check valve member168adjacent nozzle chamber end162. The high pressure adjacent nozzle chamber end162may cause check valve member168to move out of contact with nozzle seat190, allowing a second flow of fuel to flow out of nozzle chamber152and into nozzle chamber150and sac154. The second flow of fuel may also flow out through the one or more orifices82into cylinder16. Thus, in step616, because both control valves116and118are energized, both the first and second flows of fuel may flow out of fuel injector26or128into cylinder16. One of ordinary skill in the art would recognize that an amount of fuel being injected into cylinder16in step616may be larger than an amount of fuel injected into cylinder16in step610. Method600may include a step of determining whether crank angle θ is greater than crank angle “θ3” (Step618). In step618, controller30may perform functions similar to those discussed above with respect to, for example, step606to determine the crank angle θ. Controller may compare the determined value of crank angle θ with the threshold value θ3, which may signify an end of fuel injection. When controller30determines that the crank angle θ measured by, for example, crank angle sensor32is less than or equal to crank angle θ3(Step618: NO), controller30may proceed to step620of continuing to operate both the first check valve member and the second check valve member. In this step, controller30may continue to keep both solenoid120and solenoid122energized to allow both the first and the second flows of fuel to flow out of orifices82of fuel injector26or128. When controller30determines, however, that the crank angle θ measured by, for example, crank angle sensor32is greater than crank angle θ3(Step612: YES), controller30may proceed to step622. Method600may include a step of stopping fuel injection into cylinder16(Step622). In step622, controller30may be configured to de-energize both solenoids120and122. De-energizing solenoids120and122may cause control valves116and118to return to their first positions due to the biasing force exerted by biasing member124. Movement of control valves116and118to their first positions may block the connection between control chambers74and76and drain outlet68. Because control chambers74and76may be also connected to fuel inlet66, blocking the connection between control chambers74and76and drain outlet68may subject control chambers74and76to a pressure of common rail28. This may cause check valve members70and72to move towards injection ends86and90, respectively. As a result, check valve members70and72may sealingly come into contact with nozzle seats102and108, respectively, and block the one or more orifices82, stopping a flow of fuel from nozzle chamber100and nozzle chamber106into cylinder16. Similarly, when controller30is configured to control fuel injector128, de-energizing solenoids120and122may block the connection between control chambers178and182and drain outlet68. Because control chambers178and182may be also connected to fuel inlet66via passageways174and176, blocking the connection between control chambers178and182and drain outlet68may subject control chambers178and182to a pressure of common rail28. This may cause check valve members156and168to move towards injection end160and nozzle chamber end162, respectively. As a result check valve members156and168may sealingly come into contact with nozzle seats186and190, respectively, and block the one or more orifices82and passageway164, stopping a flow of fuel from nozzle chamber150and nozzle chamber152into cylinder16. FIG.7illustrates an exemplary chart700showing a variation of the fuel flow rate through the one or more orifices82into cylinder16with time corresponding to method600described above. The chart ofFIG.7may be sometimes referred to as illustrating a rate shape. As illustrated inFIG.7, controller30may energize solenoid120at time t1(corresponding to crank angle θ1). Controller30may maintain solenoid122in a de-energized state until time t2(corresponding to crank angle θ2). At time t2, controller30may energize solenoid122while also energizing solenoid120, causing an increase in the rate of fuel flow into cylinder16as seen inFIG.7. Controller30may de-energize solenoids120and122at time t3(corresponding to crank angle θ3), which may cause the flow rate of fuel from the one or more orifices to reduce to zero. Thus,FIG.7shows an exemplary injection method in which a small amount of fuel is initially injected into cylinder16between time t1and t2, and a much larger amount of fuel is injected into cylinder16between time t2and t3. Introducing a smaller amount of fuel between times t1and t2in the initial stages of the combustion cycle may help reduce a temperature in cylinder16, which in turn may help to reduce an amount of soot and/or NOxproduced in cylinder16during combustion. It is to be understood that method600and the corresponding rate shape illustrated inFIG.7may correspond to an exemplary method that may be performed by controller30and fuel system20. It is contemplated that fuel injectors26or128may be operated in many different ways to alter the rate and amount of fuel injected into cylinder16during a combustion cycle. For example, in some exemplary embodiments, check valve members70or156may be operated at crank angles greater than θ2, to inject additional fuel towards the end of a combustion cycle, to help in combusting soot produced during the combustion cycle. In other exemplary embodiments, both check valve members70,72, or156,168may be operated between crank angles θ1and θ2, and only check valve members70or156may be operated at angles greater than θ2. It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed fuel injector. Oher embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed fuel injector. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents. | 46,884 |
11859584 | DESCRIPTION OF EMBODIMENTS 1. First Embodiment Hereinafter, a solenoid valve control device according to a first embodiment of the present invention will be described. In the drawings, the common members are denoted by the same reference signs. [Internal Combustion Engine System] First, a configuration of an internal combustion engine system equipped with a solenoid valve control device according to the present embodiment will be described.FIG.1is an overall configuration diagram of an internal combustion engine system equipped with a fuel injection control device according to an embodiment. An internal combustion engine (engine)101illustrated inFIG.1is a four-cycle engine that repeats four strokes of a suction stroke, a compression stroke, a combustion (expansion) stroke, and an exhaust stroke, and is, for example, a multi-cylinder engine including four cylinders. Note that the number of cylinders included in the internal combustion engine101is not limited to four, and may include three, six, or eight or more cylinders. The internal combustion engine101includes a piston102, an intake valve103, and an exhaust valve104. The intake air (sucked air) into the internal combustion engine101passes through an air flow meter (AFM)120that detects the amount of air flowing in, and a flow rate thereof is adjusted by a throttle valve119. The air that has passed through the throttle valve119is sucked into a collector115that is a branch portion, and then supplied to a combustion chamber121of each cylinder through an intake pipe110and an intake valve103provided for each cylinder. On the other hand, the fuel is supplied from a fuel tank123to a plurality of high-pressure fuel pumps125by a low-pressure fuel pump124, and is increased to pressure necessary for fuel injection by each high-pressure fuel pump125. That is, the high-pressure fuel pump125moves up and down a plunger (described later with reference toFIG.3) provided in the high-pressure fuel pump125by power transmitted from an exhaust camshaft (not illustrated) of an exhaust cam128, and pressurizes (boosts) the fuel in the high-pressure fuel pump125. An on-off valve (an electromagnetic suction valve300to be described later) driven by a solenoid is provided in a suction port of the high-pressure fuel pump125. The solenoid is connected to an engine control unit (ECU)109. The ECU109includes a solenoid valve control device that controls driving of a solenoid valve. The ECU109controls the solenoid to drive the on-off valve so that the pressure (fuel pressure) of the fuel discharged from the high-pressure fuel pump125becomes desired pressure. The fuel boosted by the high-pressure fuel pump125is fed to a fuel injection valve105via a common rail129. A plurality of the common rails129is provided corresponding to the plurality of high-pressure fuel pumps125, and each common rail accumulates the fuel discharged by the high-pressure fuel pump125. The fuel injection valve105is an in-cylinder direct injection type capable of injecting fuel into the combustion chamber121a plurality of times in one cycle. The fuel injection valve105operates a valve body to inject fuel, for example, by supplying (energizing) a drive current to an electromagnetic coil (solenoid). The fuel injection valve105receives a command (injection pulse) from the ECU109, and injects fuel into the combustion chamber121by opening for a time designated by the command. Note that the total amount of fuel (total fuel injection amount) injected from the fuel injection valve105in one cycle can be determined in advance, and each value (injection amount of each time) of the fuel injection amount of the fuel injection performed a plurality of times can also be determined in advance. In addition, the internal combustion engine101is provided with a fuel pressure sensor (fuel pressure sensor)126that measures the fuel pressure in the common rail129. The fuel pressure measured by the fuel pressure sensor126is an actual fuel pressure supplied to the fuel injection valve105, that is, actual fuel pressure. The ECU109transmits a control command for setting the fuel pressure in the common rail129to desired pressure to the fuel injection valve105based on the measurement result of the fuel pressure sensor126. That is, the ECU109performs so-called feedback control to set the fuel pressure in the common rail129to the desired pressure. Furthermore, each combustion chamber121of the internal combustion engine101is provided with an ignition plug106, an ignition coil107, and a water temperature sensor108. The ignition plug106exposes the electrode portion in the combustion chamber121, and ignites the air-fuel mixture in which the sucked air and the fuel are mixed in the combustion chamber121by discharge. The ignition coil107creates a high voltage for discharging of the ignition plug106. The water temperature sensor108measures the temperature of cooling water for cooling the cylinder of the internal combustion engine101. The ECU109performs energization control of the ignition coil107and ignition control by the ignition plug106. The air-fuel mixture in which the sucked air and the fuel are mixed in the combustion chamber121is burned by a spark emitted from the ignition plug106, and the piston102is pushed down by this pressure. An exhaust gas generated by the combustion is discharged to an exhaust pipe111through the exhaust valve104. The exhaust pipe111is provided with a three-way catalyst112and an oxygen sensor113. The three-way catalyst112purifies harmful substances such as nitrogen oxides (NOx) contained in the exhaust gas. The oxygen sensor113detects the oxygen concentration contained in the exhaust gas and outputs the detection result to the ECU109. The ECU109performs feedback control based on the detection result of the oxygen sensor113so that the fuel injection amount supplied from the fuel injection valve105becomes the target air-fuel ratio. A crankshaft131is connected to the piston102via a connecting rod132. Then, the reciprocating motion of the piston102is converted into a rotational motion by the crankshaft131. A crank angle sensor116is attached to the crankshaft131. The crank angle sensor116detects the rotation and the phase of the crankshaft131and outputs the detection result to the ECU109. The ECU109can detect the rotational speed of the internal combustion engine101based on the output of the crank angle sensor116. Signals from the crank angle sensor116, an air flow meter120, the oxygen sensor113, an accelerator opening sensor122indicating an opening degree of an accelerator operated by a driver, the fuel pressure sensor126, and the like are input to the ECU109. The ECU109calculates a required torque of the internal combustion engine101and determines whether or not the engine is in an idle state, based on a signal supplied from the accelerator opening sensor122. Further, the ECU109calculates a sucked air amount necessary for the internal combustion engine101from the required torque and the like, and outputs an opening degree signal corresponding thereto to the throttle valve119. The ECU109calculates the fuel amount and the number of injections corresponding to the sucked air amount of each cylinder (combustion chamber121) by using outputs of various sensors. Then, the ECU109outputs a fuel injection signal corresponding to the calculated fuel amount and the number of injections to the fuel injection valve105. Further, the ECU109outputs an energization signal to the ignition coil107and outputs an ignition signal to the ignition plug106. The internal combustion engine101is mainly required to have low fuel consumption, a high output, and exhaust purification, and is required to reduce noise and vibration as additional values. In the high-pressure fuel pump125, when the electromagnetic suction valve is opened and closed, the valve body and an anchor collide with the stopper, thereby generating noise. [Configuration of ECU] Next, a configuration of the ECU109illustrated inFIG.1will be described with reference toFIG.2. FIG.2is a schematic configuration diagram of the ECU109. The ECU109includes an input circuit203, an A/D converter204, a central processing unit (CPU)205as a central processing unit, and an output circuit210. The CPU205implements a plurality of functions to be described later by executing a program stored in advance. Note that the ECU may include a field programmable gate array (FPGA) that is a rewritable logic circuit or an application specific integrated circuit (ASIC) that is an application specific integrated circuit. The input circuit203takes in a signal output from sensors201(oxygen sensor113, crank angle sensor116, air flow meter120, accelerator opening sensor122, and the like) as an input signal202. When the input signal202is an analog signal, the input circuit203removes a noise component or the like from the input signal202, and outputs the noise-removed signal to the A/D converter204. The A/D converter204converts the analog signal into a digital signal and outputs the digital signal to the CPU205. The CPU205takes in the digital signal output from the A/D converter204and executes a control logic (program) stored in advance to execute a wide variety of calculations, diagnosis, control, and the like. The calculation result of the CPU205is output as a control signal211from the output circuit210, and drives actuators212provided in the intake valve103, the exhaust valve104, the fuel injection valve105, the plurality of high-pressure fuel pumps125, and the like. On the other hand, in a case where the input signal202is a digital signal, the digital signal is directly transmitted from the input circuit203to the CPU205via a signal line206, and the CPU205executes necessary calculation, diagnosis, control, and the like. Further, the CPU205and the A/D converter204constitute a microcomputer (referred to as a “microcomputer” below)220. The microcomputer220is a specific example of a control unit according to the present invention, and performs filter processing, solenoid valve diagnosis processing, and the like to be described later. The filter processing and the solenoid valve diagnosis processing may be performed by hardware resources of the microcomputer220, or may be performed by using software. [Configuration of High-Pressure Fuel Pump] Next, a configuration of a fuel system according to the present embodiment will be described with reference toFIG.3. FIG.3is an overall configuration diagram of the fuel system according to the present embodiment of the present invention. As illustrated inFIG.3, the high-pressure fuel pump125pressurizes the fuel supplied from the fuel tank123and pressure-feeds the fuel to the common rail129. The fuel is supplied from the fuel tank123to the low-pressure fuel pump124, and is guided from the low-pressure fuel pump124to a fuel introduction port of the high-pressure fuel pump125. At this time, the fuel is regulated to constant pressure by a pressure regulator152. The high-pressure fuel pump125includes a casing323. The casing323is provided with a communication port321, an outflow port322, an inflow port325, and a pressurizing chamber311. In addition, the high-pressure fuel pump125includes a plunger302that moves up and down by rotation of a pump drive cam301attached to a camshaft of the internal combustion engine101, an electromagnetic suction valve300that opens and closes in synchronization with the vertical movement of the plunger302, and a discharge valve310that discharges fuel to the common rail129. When the plunger302descends, the volume of the pressurizing chamber311increases. When the plunger302rises, the volume of the pressurizing chamber311decreases. That is, the plunger302is disposed to reciprocate in a direction of increasing and reducing the volume of the pressurizing chamber311. The discharge valve310opens and closes the outflow port322. A spring portion326biases the discharge valve310in a valve opening direction. That is, the discharge valve310is constantly biased in a direction in which the outflow port322is closed. When the pressure of the fuel in the pressurizing chamber311becomes larger than a biasing force of the spring portion326, the outflow port322is opened. As a result, the fuel in the pressurizing chamber311is discharged to the common rail129. The electromagnetic suction valve300is a normally open type solenoid valve. A force acts in a valve opening direction during non-energization, and a force acts in a valve closing direction during energization. The electromagnetic suction valve300includes a valve body303, a first spring309that biases the valve body303in the valve opening direction, a second spring315that biases the valve body303in the valve closing direction, a solenoid305, and an anchor304. The valve body303is formed in a substantially rod shape, and the anchor304is provided at one end portion in an axial direction. Further, an abutment piece303ais formed at the other end portion of the valve body303. The abutment piece303aabuts on a seat portion307provided in the inflow port325when the valve is closed. Thus, the valve body303closes the communicating portion between the inflow port325and the pressurizing chamber311. One end of the first spring309is connected to the anchor304. The other end of the first spring309is connected to the casing323. One end of the second spring315is connected to a stopper308disposed between the valve body303and the pressurizing chamber311. The other end of the second spring315is connected to an end portion of the valve body303on an opposite side of the anchor304. The solenoid305faces the anchor304. When a current flows through the solenoid305, an electromagnetic force is generated between the solenoid305and the anchor304. As a result, the anchor304is pulled in the valve closing direction which is a direction against the spring force of the first spring309(left side inFIG.3). In the high-pressure fuel pump125, on/off of energization of the solenoid305is controlled to control the operation of the anchor304in the axial direction (left-right direction inFIG.3). In a state where the energization of the solenoid305is off, the anchor304is constantly biased in the valve opening direction (the right direction inFIG.3) by the first spring309. Thus, the valve body303is held at a valve opening position. When the energization of the solenoid305is turned on, an electromagnetic attractive force is generated between a fixing portion306(magnetic core) and the anchor304. As a result, the anchor304is attracted in the valve closing direction (left direction inFIG.3) against the spring force of the first spring309. In a state where the anchor304is attracted to the fixing portion306, the valve body303acts as a check valve that opens and closes based on the differential pressure between the upstream side and the downstream side and the biasing force of the second spring315. When the pressure on the downstream side of the valve body303increases, the valve body303moves in the valve closing direction. When the valve body303moves by a lift amount set in the valve closing direction, the valve body303is seated on the seat portion307. As a result, the electromagnetic suction valve300is closed, and it is not possible for the fuel in the pressurizing chamber311to flow back to the low-pressure pipe side. When the plunger302descends, and the electromagnetic suction valve300is opened, the fuel flows from the inflow port325into the pressurizing chamber311. A stroke in which the plunger2descends is referred to as a suction stroke below. On the other hand, when the plunger302rises, and the electromagnetic suction valve300is closed, the fuel in the pressurizing chamber311is boosted, passes through the discharge valve310(outflow port322), and then is pressure-fed to the common rail129. A stroke in which the plunger302rises is referred to as a compression stroke below. If the electromagnetic suction valve300is closed during the compression stroke, the fuel sucked into the pressurizing chamber311during the suction stroke is pressurized and discharged to the common rail129side. On the other hand, if the electromagnetic suction valve300is opened during the compression stroke, the fuel in the pressurizing chamber311is pushed back toward the inflow port325and is not discharged toward the common rail129. As described above, the fuel discharge by the high-pressure fuel pump125is operated by opening and closing the electromagnetic suction valve300. The opening and closing of the electromagnetic suction valve300are controlled by the ECU109(solenoid valve control device). The common rail129accumulates the fuel discharged from the high-pressure fuel pump125. A plurality of fuel injection valves105, a fuel pressure sensor126, and a pressure adjustment valve (referred to as a “relief valve” below)355are mounted to the common rail129. When the fuel pressure in the common rail129exceeds a predetermined value, the relief valve355is opened and prevents breakage of the pipe. The plurality of fuel injection valves105are mounted in accordance with the number of cylinders (combustion chambers121), and inject fuel in accordance with the drive current output from the ECU109. The fuel pressure sensor126outputs the detected pressure data to the ECU109. The ECU109calculates an appropriate injection fuel amount (target injection fuel length), appropriate fuel pressure (target fuel pressure), and the like based on engine state quantities (for example, a crank rotation angle, a throttle opening degree, an engine rotational speed, and fuel pressure) obtained from various sensors. In addition, the ECU109controls driving of the high-pressure fuel pump125and the plurality of fuel injection valves105based on the calculation result. That is, the ECU109(solenoid valve control device) includes a pump control unit that controls the high-pressure fuel pump125and an injection valve control unit that controls the fuel injection valve105. [Operation of High-pressure Fuel Pump] Next, an operation of the high-pressure fuel pump according to the present embodiment will be described with reference toFIG.4. FIG.4is a time chart for explaining the operation of the high-pressure fuel pump125. The electromagnetic suction valve300opens and closes in synchronization with the rising and descending of the plunger302. The ECU109(solenoid valve control device) detects the rotation angle of the pump drive cam301, and starts applying of a voltage V to both ends of the solenoid305after the pump drive cam301rotates from the top dead center (TDC) to a predetermined angle (P_ON timing), for example (timing t1). A current I flowing through the solenoid305increases in accordance with Expression 1. Note that L indicates the inductance of the solenoid305and the wiring, and R indicates the resistance of the solenoid305and the wiring. LdI/dt=V−RI(Expression 1) As the current I increases, the magnetic attraction force Fmag by which the fixing portion306(magnetic core) attracts the anchor304increases. When the magnetic attraction force Fmag becomes larger than the spring force Fsp of the first spring309, the anchor304pressed by the spring force Fsp starts moving toward the fixing portion306(timing t2). When the anchor304moves toward the fixing portion306, the valve body303pressed by the fuel pressurized by the rising of the plunger302moves to the fixing portion306with following the anchor304. Then, the abutment piece303aof the valve body303collides with the seat portion307. That is, the valve body303is seated on the seat portion307. As a result, the flow path of the fuel (dotted line inFIG.3) is closed, and the fuel pressurized by the rising of the plunger302cannot return to the low pressure pipe side. As a result, the fuel pressure in the pressurizing chamber311increases. (Timing t4). When the fuel pressure of the pressurizing chamber311becomes larger than the spring force Fsp out for biasing the discharge valve310, the discharge valve310is opened. As a result, the fuel pressurized by the rising of the plunger302is discharged to the common rail129. Then, when the drive pulse is turned off at a timing t5, a reverse voltage is applied to the solenoid305. Thus, a holding current supplied to the solenoid305is cut off. When the cam angle exceeds the top dead center and the plunger302starts to descend (timing t6), the fuel pressure in the pressurizing chamber311decreases. When the fuel pressure of the pressurizing chamber311becomes smaller than the spring force Fsp out, the discharge valve310is closed. As a result, the discharge of the fuel by the high-pressure fuel pump125is ended. Since the fuel pressure in the pressurizing chamber311decreases, the anchor304moves from a valve closing position to a valve opening position together with the valve body303(timings t7 to t8). With such an operation, the high-pressure fuel pump125feeds the fuel from a low-pressure pipe to the common rail129. In this process, noise is generated when the anchor304collides with the fixing portion306to complete the valve closing (timing t4 inFIG.4) and when the anchor304and the valve body303collide with the stopper308to complete the valve opening (timing t8 inFIG.4). The noise may make the driver uncomfortable, particularly at an idle time. In the present embodiment, noise at the time of completing the valve closing is reduced. [Peak Current and Holding Current] Next, the peak current and the holding current according to the present embodiment will be described with reference toFIG.4. The current for driving the high-pressure fuel pump125is roughly divided into two pieces. That is, the drive current of the high-pressure fuel pump125is divided into a peak current (hatched portion of a current waveform inFIG.4) and a holding current (horizontal line portion of the current waveform inFIG.4). As illustrated inFIG.4, the maximum current value of the peak current is set as Im, and the maximum current value of the holding current is set as Ik. When the peak current flows, a force for closing the valve is applied to the valve body303and the anchor304which are biased by the first spring309and are stopped at the valve opening position. On the other hand, when the holding current flows, the anchor304approaching the fixing portion306is attracted until colliding with the fixing portion306. Further, after the anchor304collides with the fixing portion306, the contact state is maintained. When the application amount of the peak current is reduced, the biasing of closing the valve is weakened. Thus, it is possible to reduce noise. However, when the application amount of the peak current is excessively reduced, the closing of the electromagnetic suction valve300fails. Therefore, it is desired to reduce the application amount of the peak current as much as possible within a range in which the electromagnetic suction valve300is closed. Basically, the application amount of the peak current at the limit (minimum) at which the electromagnetic suction valve is closed depends on the individual characteristics of the high-pressure fuel pump.FIG.5is a diagram illustrating variations in individual characteristics of the high-pressure fuel pump.FIG.5illustrates a relationship between an average speed v_ave during valve closing (average value from valve closing start to valve closing completion) and a peak current integrated value II for a case of the standard spring force Fsp, a case where the spring force Fsp has an upper limit due to manufacturing variations, and a case where the spring force Fsp has a lower limit due to manufacturing variations. Note that, in the present embodiment, the application amount of the peak current is set to the integrated value of the current, but similar individual characteristics are established even though the application amount of the peak current is replaced with the integrated value of the square of the current or the integrated value of the product of the current and the voltage. FromFIG.5, it is found that the relationship between the peak current integrated value II and the average speed v_ave varies depending on the spring force Fsp. That is, when the average speed required in a certain solenoid valve is indicated by a broken line, the required peak current integrated value II greatly varies in the range of A to C due to individual differences. When a valve closing limit current with respect to the lower limit product of the spring force Fsp is set to the upper limit product of the spring force Fsp, the magnetic attraction force generated by the solenoid becomes smaller than the spring force, and the closing of the electromagnetic suction valve fails. Therefore, as the valve closing limit current, it is necessary to select the valve closing limit current with respect to the upper limit product of the spring force Fsp. However, when the lower limit product of the spring force Fsp is controlled by the valve closing limit current with respect to the upper limit product of the spring force Fsp, an excessive magnetic attraction force is generated as compared with the spring force. As a result, the electromagnetic suction valve is closed at a speed more than necessary. FIG.6is a diagram illustrating the relationship between the drive current value and the noise level of the high-pressure fuel pump. As illustrated inFIG.6, the noise level increases as the peak current integrated value II increases. In addition, as described with reference toFIG.5, it is necessary to set the value of the valve closing limit current to the value (current value C) corresponding to the upper limit product of the spring force Fsp. However, the current value required for the lower limit product of the spring force Fsp is the current value A. Therefore, the width of the double-headed arrow illustrated inFIG.5varies in the noise level. That is, if the current value applied to the lower limit product of the spring force Fsp can be reduced to the current value A, which is an originally necessary value, it is possible to reduce the noise level corresponding to the variation. [Valve Closing Detection Using Fuel Rail Pressure] In order to apply the current value corresponding to the spring force Fsp, in other words, an appropriate current value corresponding to the pump individual difference to the solenoid valve, it is necessary to detect the pump individual difference. In the present embodiment, fuel rail pressure (fuel pressure in the common rail129) is used as means for detecting an individual difference. The high-pressure fuel pump125and the fuel injection valve105are connected to the common rail129having a pressure accumulation function. The action of each solenoid valve in the high-pressure fuel pump125and the fuel injection valve105has a close relationship with the fuel pressure in the common rail129. For example, when the electromagnetic suction valve300of the high-pressure fuel pump125is closed, the fuel pressure in the pressurizing chamber311increases. As a result, the fuel in the pressurizing chamber311is discharged from the discharge valve310, and the fuel pressure in the common rail129increases. That is, it can be said that the valve closing success of the electromagnetic suction valve300is an increase in the fuel pressure in the common rail129. On the other hand, when the solenoid valve of the fuel injection valve105is closed, the fuel is injected from the injection port of the fuel injection valve105, so that the fuel pressure in the common rail129decreases. That is, it can be said that the valve closing success of the solenoid valve in the fuel injection valve105is a decrease in the fuel pressure in the common rail129. FIG.7is a diagram illustrating a relationship among fuel discharge of the high-pressure fuel pump, fuel injection of the fuel injection valve, and fuel pressure of the common rail. In the high-pressure fuel pump125, fuel is discharged through the discharge valve310(fuel discharge602of the high-pressure pump) in accordance with the decrease in the volume of the pressurizing chamber311due to the rising of the plunger302(increase in the cam lift amount601) during a period from the completion of the valve closing of the electromagnetic suction valve300to the TDC. Further, the fuel injection valve105injects fuel based on an injection instruction from the ECU109(fuel injection603of the fuel injection valve). As a result, the fuel pressure604in the common rail129generally transitions through four regions A, B, C, and D. The region A is an influence region of the fuel injection valve105, and the fuel pressure604in the common rail129decreases in accordance with the fuel injection amount by the fuel injection valve105. The region B next to the region A is a region in which the fuel pressure604in the common rail129is held. In the region B, the discharge of fuel by the high-pressure fuel pump125and the injection of fuel by the fuel injection valve105are not performed. Therefore, the fuel pressure604in the common rail129is maintained at a value decreased in the region A. The region C next to the region B is an influence region of the high-pressure fuel pump125, and the fuel pressure604in the common rail129increases in accordance with the fuel discharge amount by the high-pressure fuel pump125. The region D next to the region C is a region in which the fuel pressure in the common rail129is held. Also in this region, similarly to the region B, fuel discharge by the high-pressure fuel pump125and fuel injection by the fuel injection valve105are not performed. Therefore, the fuel pressure604in the common rail129is maintained at a value increased in the region C. Basically, the injection amount by the fuel injection valve105and the discharge amount of the high-pressure fuel pump125are balanced to achieve the target fuel pressure of the system as the average fuel pressure. From the relationship among the pump discharge, the fuel injection valve injection, and the rail fuel pressure as described above, it is found that it is possible to grasp the valve action of the electromagnetic suction valve300of the high-pressure fuel pump125and the fuel injection valve105by detecting the fuel pressure in the common rail129. Specifically, by detecting the fuel pressure in the common rail129, it is possible to detect whether the electromagnetic suction valve300and the fuel injection valve105are closed. In addition, it is possible to easily detect the fuel pressure in the common rail129from the value of the fuel pressure sensor mounted in a general direct injection system. As described above, the monitored value required in the present invention is only the value of the fuel pressure in the common rail129that can be read from the known fuel pressure sensor126. Therefore, in the present invention, it is not necessary to newly develop a circuit and a control, and it is possible to implement a shorter delivery time and lower cost than in the case of newly developing a circuit and a control in the related art. On the other hand, conventionally, the current/voltage value is directly detected in order to detect whether the solenoid valve is closed. As a result, the cost and the lead time increase. [Control of Electromagnetic Suction Valve] Next, control processing of the electromagnetic suction valve300will be described with reference toFIG.8.FIG.8is a flowchart of solenoid valve control in the high-pressure fuel pump according to the first embodiment of the present invention. First, the ECU109(solenoid valve control device) acquires fuel pressure data in the common rail129(S101). In this processing, fuel pressure data is acquired from the fuel pressure sensor126. Note that the sampling period is desirably fine. However, even with a resolution of a level set in the related art, such as 1 ms, 2 ms, or 4 ms, it is possible to ensure sufficient accuracy for the present control as long as the resolution is in a low rotation to middle rotation range where noise becomes a problem in an engine in general. Next, the ECU109(solenoid valve control device) applies filter processing corresponding to the application, on the acquired fuel pressure data (S102).FIG.9is a diagram illustrating a filter example used for fuel pressure data. Filter1is calculated by using Filter coefficient801. Filter2is calculated by using Filter coefficient802. Filter3is calculated by using Filter coefficient803. That is, Filter1, Filter2, and Filter3are calculated by the following Expressions (2) to (4), respectively. Filter 1=(1×Pf(t))+(−1×Pf(t−1)) (Expression 2) Filter 2=(1×Pf(t))+(0×Pf(t−1))+(−1×Pf(t−2)) (Expression 3) Filter 3=(1×Pf(t))+(0.5×Pf(t−1))+(−0.5×Pf(t−2))+(−1×Pf(t−3)) (Expression 4) Filters1to3are filters that extract the difference by cutting the DC component. For Filter1, a sampling period is the peak of the gain of change. For Filter2, twice the sampling period is the peak of the gain of change. For Filter3, three times the sampling period is the peak of the gain of change. Therefore, it is preferable to set the filter at a well-balanced point from the viewpoint of detectability with the sampling frequency and noise removal. Then, the ECU109(solenoid valve control device) determines whether or not closing of the electromagnetic suction valve300succeeds by comparing pressure data (fuel pressure901) after the filter processing with a threshold value902set in advance (S103). The process of S103corresponds to solenoid valve diagnosis processing according to the present invention. In this processing, when the fuel pressure data after the filter process exceeds the threshold value, it is determined that the valve is successfully closed. When the fuel pressure data after the filter process is equal to or smaller than the threshold value, it is determined that the valve closing has failed. FIG.10is a diagram illustrating the relationship among the fuel discharge of the high-pressure fuel pump, the fuel injection of the fuel injection valve, the fuel pressure of the common rail, and fuel pressure after filter processing according to the first embodiment of the present invention. As illustrated inFIG.10, when the fuel pressure901after the filter processing exceeds a threshold value902, it is considered that the fuel discharge amount has reached the target discharge amount. Therefore, it can be determined that the fuel in the pressurizing chamber311in the high-pressure fuel pump125has not returned to the inflow port325(seeFIG.3) and the valve has been successfully closed. On the other hand, when the fuel pressure901after the filter processing is equal to or smaller than the threshold value902, it is considered that the fuel discharge amount does not reach the target discharge amount. Therefore, it can be determined that the fuel in the pressurizing chamber311in the high-pressure fuel pump125has returned to the inflow port325(seeFIG.3) and the valve closing has failed. A value preventing erroneous detection in consideration of noise, detection accuracy, and the like is considered as the lower limit side of the threshold value902. In addition, a value allowing reliable detection even at the gain lower limit when the pump performs discharge with including variations is considered as the upper limit side of the threshold value902. The threshold value902is set between the lower limit side and the upper limit side. If only the closing of the electromagnetic suction valve300is detected, considering the lower limit side is not a program as described above. However, in a scene where the accuracy of the discharge amount is required, the electromagnetic suction valve300is closed, but the responsiveness is delayed, so that the accuracy of the discharge flow rate may be a problem. Therefore, when the lower limit side of the threshold value is set, it is necessary to take into consideration a factor of a minimum required discharge flow rate in addition to preventing erroneous detection in consideration of noise, detection accuracy, and the like. In addition, the threshold value902may be a fixed value, but, in a case where there is not one control scene, it is necessary to set the threshold value by MAP in accordance with the fuel pressure, the discharge amount of the pump, and the like, or to set the threshold value variably. The conversion from the discharge flow rate to the pressure fluctuation can be calculated from the pressure, the volume, the fuel physical properties, and the like by using an expression of the compressible fluid. Conversely, the discharge flow rate of the high-pressure fuel pump can be calculated from the change amount of the measurement signal (pressure data after difference filtering processing). In the processing of S103, the discharge flow rate of the high-pressure fuel pump may be calculated, and it may be determined whether the current setting value is corrected to a low value or a high value from the calculated discharge flow rate. For example, when the calculated discharge flow rate of the high-pressure fuel pump is greater than a predetermined value, the same determination (YES determination) as the case where the valve is successfully closed is made. On the other hand, when the calculated discharge flow rate of the high-pressure fuel pump is equal to or smaller than the predetermined value, the same determination (NO determination) as the case where the valve closing has failed is made. In addition, as illustrated inFIG.10, a determination window903is set every 1 cam cycle so that the range in which the fuel is actually discharged within the range from the bottom dead center to the top dead center of the plunger302from which the high-pressure fuel pump125can discharge the fuel can be reliably covered. Note that it is possible to reduce the risk of erroneous detection due to noise or the like by limiting the determination window903to a necessary range. When it is determined in S103that the valve is successfully closed (YES determination in S103), the ECU109(solenoid valve control device) determines that the current current setting value has a margin. Then, the ECU109(solenoid valve control device) corrects the current setting value to a value lower than a setting value at the current time (S104). Then, the ECU109(solenoid valve control device) acquires fuel pressure data again. That is, the ECU109(solenoid valve control device) returns the process to S101. The smaller the correction amount (feedback amount) of the current setting value in S104, the higher the accuracy. However, the finer the correction amount of the current setting value, the more susceptible to noise, and the more time is required for determination. Therefore, the correction amount (feedback amount) of the current setting value in S104may be set in consideration of both the time allocated to the main control and the required accuracy. On the other hand, when it is determined in S103that the valve closing has failed (NO in S103), the ECU109(solenoid valve control device) determines that the current current setting value is low. Then, the ECU109(solenoid valve control device) corrects the current setting value to a value higher than the setting value at the current time (S105). Then, the ECU109(solenoid valve control device) determines that the current setting value corrected in the processing of S105is the minimum current value, and then ends the control. The correction amount (feedback amount) of the current setting value in S105may be set to be the current setting value for which the valve closing success has been achieved last. However, it is desirable to set the correction amount (feedback amount) of the current setting value in S105in consideration of an appropriate safety factor based on robustness. In addition, the correction amount (feedback amount) of the current setting value in S104and S105may be stored in the storage unit as a map value or may be variably set in accordance with the operation scene. In the above-described control of the solenoid valve, filter processing is performed on the pressure fluctuation every shot (every energization pulse of the solenoid valve) to determine whether closing of the solenoid valve succeeds. Therefore, it is possible to more accurately and directly detect the valve closing success/failure of the solenoid valve as compared with a method of determining the valve closing success/failure of the solenoid valve simply based on whether the fuel pressure decreases or increases. In addition, by feeding back the valve closing success/failure of the solenoid valve to the drive current value, it is possible to drive the solenoid valve at the minimum current value, and it is possible to realize significant noise reduction and power saving. Furthermore, since only the fuel rail fuel pressure value (fuel pressure data in the common rail129), which is an existing monitored value, is used to detect the valve closing of the solenoid valve, it is possible to detect the valve closing of the solenoid valve without a need to add a new control circuit. As a result, it is possible to significantly shorten the development period and to significantly reduce the cost. 2. Second Embodiment Next, a solenoid valve control device according to a second embodiment of the present invention will be described. The solenoid valve control device according to the second embodiment of the present invention has the same configuration as the solenoid valve control device according to the first embodiment described above. The solenoid valve control device according to the second embodiment is different from the solenoid valve control device according to the first embodiment in control of the electromagnetic suction valve. Therefore, here, the control of the electromagnetic suction valve according to the second embodiment will be described, and the description of the common configuration of the ECU (solenoid valve control device), the high-pressure fuel pump, the electromagnetic suction valve, and the like will be omitted. [Control of Electromagnetic Suction Valve] Control processing of an electromagnetic suction valve300according to the second embodiment will be described with reference toFIG.11. FIG.11is a flowchart of solenoid valve control according to the second embodiment. First, the ECU109(solenoid valve control device) performs scene determination (S201). In this processing, whether or not to continue the main feedback control (processing of feeding whether or not closing of the electromagnetic suction valve succeeds back to the drive current value) is determined from the operation scene. The main feedback control is difficult to perform in all driving scenes. For example, during the transient operation, the required fuel pressure and the required discharge amount change from moment to moment, and the disturbance increases. Therefore, there is a possibility that appropriate feedback is not performed during the transient operation, and thus it is desirable not to perform the main feedback control. Specifically, examples of the scene where the main feedback control is performed include time of an engine shipping test, time of maintenance, time of a no-load operation, and time of a normal operation. When the main feedback control is performed at the time of the engine shipping test, it is possible to initially reduce noise of the solenoid valve initially (before reaching the user). When the main feedback control is performed at the time of the maintenance, it is possible to adjust the current value again assuming that the required current value has changed due to durability deterioration of the pump or the like. When the main feedback control is performed during the no-load operation (idle operation) or the normal operation, it is possible to reduce noise during the idle operation. In addition, the current value can be fed back online. When it is determined in S201that the scene is not a scene where the main feedback control is performed (NO in S201), the ECU109(solenoid valve control device) ends the control. Thus, the main feedback control is not performed. On the other hand, when it is determined in S201that the scene is the scene where the main feedback control is performed (YES determination in S201), the ECU109(solenoid valve control device) performs the processing of S202to S206. The processing of S202to S206is the same as the processing of S101to S105of the solenoid valve control according to the first embodiment. Therefore, the description of the processing of S202to S206will be omitted here. Also in the solenoid valve control according to the second embodiment, filter processing is performed on the pressure fluctuation every shot (every energization pulse of the solenoid valve) to determine whether closing of the solenoid valve succeeds. Therefore, it is possible to more accurately and directly detect the valve closing success/failure of the solenoid valve as compared with a method of determining the valve closing success/failure of the solenoid valve simply based on whether the fuel pressure decreases or increases. In addition, it is possible to drive the solenoid valve at the minimum current value, and it is possible to realize significant noise reduction and power saving. Furthermore, it is possible to detect closing of the solenoid valve by an existing circuit without a need to add a new control circuit. As a result, it is possible to significantly shorten the development period and to significantly reduce the cost. 3. Third Embodiment Next, a solenoid valve control device according to a third embodiment of the present invention will be described. The solenoid valve control device according to the third embodiment of the present invention has the same configuration as the solenoid valve control device according to the first embodiment described above. The solenoid valve control device according to the third embodiment is different from the solenoid valve control device according to the first embodiment in control of the electromagnetic suction valve. Therefore, here, the control of the electromagnetic suction valve according to the third embodiment will be described, and the description of the common configuration of the ECU (solenoid valve control device), the high-pressure fuel pump, the electromagnetic suction valve, and the like will be omitted. [Control of Electromagnetic Suction Valve] Control processing of an electromagnetic suction valve300according to the third embodiment will be described with reference toFIG.12. FIG.12is a flowchart of solenoid valve control according to the third embodiment. First, the ECU109(solenoid valve control device) performs scene determination (S301). In this processing, whether or not to continue the main feedback control (processing of feeding whether or not closing of the electromagnetic suction valve succeeds back to the drive current value) is determined from the operation scene. When it is determined in S301that the scene is not a scene where the main feedback control is performed (NO in S301), the ECU109(solenoid valve control device) ends the control. Thus, the main feedback control is not performed. On the other hand, when it is determined in S301that the scene is the scene where the main feedback control is performed (YES determination in S301), the ECU109(solenoid valve control device) performs injection influence determination of the fuel injection valve105(S302). The discharge of fuel by the high-pressure fuel pump and the fuel injection by the fuel injection valve105are large factors having an influence on the fuel pressure of the common rail129. Therefore, it is necessary to pay attention to the main feedback control in a scene where both overlap with each other. FIG.13is a diagram illustrating a relationship among fuel discharge of the high-pressure fuel pump, fuel injection of the fuel injection valve, fuel pressure of the common rail, and fuel pressure after filter processing according to the third embodiment of the present invention. As illustrated inFIG.12, when the fuel discharge602of the high-pressure fuel pump125and fuel injection1201of the fuel injection valve105are performed at the same timing, the increase in the fuel pressure due to the fuel discharge602of the high-pressure fuel pump125is canceled by the decrease in the fuel pressure due to the fuel injection1201of the fuel injection valve105. As a result, the fuel pressure1202in the common rail129does not change, and it becomes impossible to detect the valve closing of the electromagnetic suction valve300from the pressure fluctuation. In this case, the ECU109(solenoid valve control device) determines that the fuel injection1201by the fuel injection valve105has an influence on the feedback control. Since the fuel pressure1202in the common rail129has pulsation, a scene in which the timings of the fuel discharge602and the fuel injection1201completely overlap as illustrated inFIG.13is not actually assumed. However, in a scene where the discharge and the injection overlap as much as possible, whether the main feedback control can be applied is examined in consideration of the setting of the threshold value, the detection window, and the like while checking the actual pressure action. The region where the high-pressure fuel pump125can discharge the fuel is only a range where the plunger302rises (from the cam bottom dead center to the top dead center). Therefore, when the fuel injection pulse slightly overlaps the range in which the plunger302rises, it may be determined that the fuel injection by the fuel injection valve105has an influence on the main feedback control. When it is determined in S302that the fuel injection by the fuel injection valve105has an influence on the feedback control (YES determination in S302), the ECU109(solenoid valve control device) ends the control. Thus, the main feedback control is not performed. On the other hand, when it is determined in S302that the fuel injection by the fuel injection valve105does not have an influence on the main feedback control (YES determination in S302), the ECU109(solenoid valve control device) performs processing of S303to S307. The processing of S303to S307is the same as the processing of S101to S105of the solenoid valve control according to the first embodiment. Therefore, the description of the processing of S303to S307will be omitted here. Also in the solenoid valve control according to the third embodiment, filter processing is performed on the pressure fluctuation every shot (every energization pulse of the solenoid valve) to determine whether closing of the solenoid valve succeeds. Therefore, it is possible to more accurately and directly detect the valve closing success/failure of the solenoid valve as compared with a method of determining the valve closing success/failure of the solenoid valve simply based on whether the fuel pressure decreases or increases. In addition, it is possible to drive the solenoid valve at the minimum current value, and it is possible to realize significant noise reduction and power saving. Furthermore, it is possible to detect closing of the solenoid valve by an existing circuit without a need to add a new control circuit. As a result, it is possible to significantly shorten the development period and to significantly reduce the cost. 4. Fourth Embodiment Next, a solenoid valve control device according to a fourth embodiment of the present invention will be described. The solenoid valve control device according to the fourth embodiment of the present invention has the same configuration as the solenoid valve control device according to the first embodiment described above. The solenoid valve control device according to the fourth embodiment is different from the solenoid valve control device according to the first embodiment in that a fuel injection valve is applied as the solenoid valve. Here, control of the fuel injection valve according to the fourth embodiment will be described, and description of common configurations of the ECU (solenoid valve control device), the fuel injection valve, and the like will be omitted. [Control of Electromagnetic Suction Valve] Control processing of the fuel injection valve105according to the fourth embodiment will be described with reference toFIG.14. FIG.14is a flowchart of solenoid valve control according to the fourth embodiment. When the electromagnetic suction valve300of the high-pressure fuel pump125is successfully closed, the fuel pressure in the common rail129increases. On the other hand, when the fuel injection valve105is successfully closed, the fuel pressure in the common rail129decreases. As described above, since the electromagnetic suction valve300of the high-pressure fuel pump125and the fuel injection valve105have a true inverse relationship, a portion of the solenoid valve control is different. First, the ECU109(solenoid valve control device) performs scene determination (S401). In this processing, whether or not to continue the main feedback control (processing of feeding whether or not closing of the fuel injection valve succeeds back to the drive current value) is determined from the operation scene. The driving scene is the same as that in the second embodiment described above. When it is determined in S401that the scene is not a scene where the main feedback control is performed (NO in S401), the ECU109(solenoid valve control device) ends the control. Thus, the main feedback control is not performed. On the other hand, when it is determined in S401that the scene is the scene where the main feedback control is performed (YES determination in S401), the ECU109(solenoid valve control device) performs discharge influence determination of the high-pressure fuel pump125(S402). As described above, when the fuel discharge of the high-pressure fuel pump125and fuel injection of the fuel injection valve105are performed at the same timing, the increase in the fuel pressure due to the fuel discharge of the high-pressure fuel pump125is canceled by the decrease in the fuel pressure due to the fuel injection of the fuel injection valve105. As a result, the fuel pressure in the common rail129does not change, and it becomes impossible to detect the valve closing of the fuel injection valve105from the pressure fluctuation. In this case, the ECU109(solenoid valve control device) determines that the fuel discharge by the high-pressure fuel pump125has an influence on the main feedback control. For example, when the fuel injection pulse slightly overlaps the range from the cam top dead center to the bottom dead center, it may be determined that the fuel discharge by the high-pressure fuel pump125has an influence on the main feedback control. When it is determined in S402that the fuel discharge by the high-pressure fuel pump125has an influence on the feedback control (YES determination in S402), the ECU109(solenoid valve control device) ends the control. Thus, the main feedback control is not performed. On the other hand, when it is determined in S402that the fuel discharge by the high-pressure fuel pump125does not have an influence on the main feedback control (YES determination in S402), the ECU109(solenoid valve control device) performs processing of S403and S404. The processing of S403and S404is the same as the processing of S101and S102of the solenoid valve control according to the first embodiment. Therefore, the description of the processing of S403and S404will be omitted here. After the processing of S404, the ECU109(solenoid valve control device) determines whether or not closing of the fuel injection valve105succeeds by comparing the pressure data after the filter processing with a threshold value set in advance (S405). When the fuel injection valve105is successfully closed, the fuel pressure in the common rail129drops. Therefore, the threshold value is set to a negative value, and it is determined that the valve is successfully closed when the fuel pressure data after the filter processing is smaller than the threshold value. When the fuel pressure data after the filter process is equal to or greater than the threshold value, it is determined that the valve closing has failed. When it is determined in S405that the valve is successfully closed (YES in S405), the ECU109(solenoid valve control device) determines that the current current setting value has a margin. Then, the ECU109(solenoid valve control device) corrects the current setting value to a value lower than a setting value at the current time (S406). Then, the ECU109(solenoid valve control device) acquires fuel pressure data again. That is, the ECU109(solenoid valve control device) returns the process to S403. On the other hand, when it is determined in S405that the valve closing has failed (NO in S405), the ECU109(solenoid valve control device) determines that the current current setting value is low. Then, the ECU109(solenoid valve control device) corrects the current setting value to a value higher than the setting value at the current time (S407). Then, the ECU109(solenoid valve control device) determines that the current setting value corrected in the processing of S407is the minimum current value, and then ends the control. The conversion from the injection flow rate to the pressure fluctuation can be calculated from the pressure, the volume, the fuel physical properties, and the like by using an expression of the compressible fluid. Conversely, the injection flow rate of the fuel injection valve can be calculated from the change amount of the measurement signal (pressure data after difference filtering processing). In the processing of S405, the injection flow rate of the fuel injection valve may be calculated, and it may be determined whether the current setting value is corrected to a low value or a high value from the calculated injection flow rate. For example, when the calculated injection flow rate of the fuel injection valve is less than a predetermined specific value, the same determination (YES determination) as the case where the valve is successfully closed is made. On the other hand, when the calculated injection flow rate of the fuel injection valve is equal to or greater than the specific value, the same determination (NO determination) as the case where the valve closing has failed is made. Also in the solenoid valve control according to the fourth embodiment, filter processing is performed on the pressure fluctuation every shot (every energization pulse of the solenoid valve) to determine whether closing of the solenoid valve succeeds. Therefore, it is possible to more accurately and directly detect the valve closing success/failure of the solenoid valve as compared with a method of determining the valve closing success/failure of the solenoid valve simply based on whether the fuel pressure decreases or increases. In addition, it is possible to drive the solenoid valve at the minimum current value, and it is possible to realize significant noise reduction and power saving. Furthermore, it is possible to detect closing of the solenoid valve by an existing circuit without a need to add a new control circuit. As a result, it is possible to significantly shorten the development period and to significantly reduce the cost. 5. Summary As described above, the solenoid valve control device (ECU109) according to the above-described embodiment controls opening and closing of the solenoid valve in the internal combustion engine system including the fuel pump (high-pressure fuel pump125) including the plunger (plunger302) that moves up and down with the rotation of the pump drive cam (pump drive cam301) to increase or decrease the volume of the pressurizing chamber (pressurizing chamber311), the solenoid valve (electromagnetic suction valve300) for sucking the fuel into the pressurizing chamber, and the discharge valve (discharge valve310) for discharging the fuel in the pressurizing chamber, and the fuel rail (common rail129) for accumulating the fuel discharged by the fuel pump. The solenoid valve control device includes the control unit (microcomputer220) that determines whether or not closing of the solenoid valve has succeeded based on fuel pressure of the fuel rail, or calculates a discharge amount by closing the solenoid valve based on the fuel pressure of the fuel rail. This makes it possible to detect the closing of the solenoid valve, which is the motion of the valve body in response to the drive command, without adding a special circuit such as a low-pass filter circuit or an operational amplifier circuit. In addition, the control unit (microcomputer220) of the solenoid valve control device (ECU109) according to the above-described embodiment determines whether closing of the solenoid valve (electromagnetic suction valve300) succeeds or calculates the discharge amount by closing the solenoid valve, based on the measurement signal output from the fuel pressure sensor (fuel pressure sensor126) attached to the fuel rail (common rail129). As a result, it is possible to easily acquire the fuel pressure in the fuel rail. In addition, the control unit (microcomputer220) of the solenoid valve control device (ECU109) according to the above-described embodiment performs filter processing on the measurement signal output from the fuel pressure sensor (fuel pressure sensor126), and compares the filtered measurement signal with a predetermined threshold value to determine whether closing of the solenoid valve (electromagnetic suction valve300) succeeds or calculate the discharge amount by closing the solenoid valve. As a result, it is possible to improve the accuracy of the valve closing success or failure of the solenoid valve. In addition, it is possible to improve the accuracy of the calculated discharge amount by closing the solenoid valve. In addition, the control unit (microcomputer220) of the solenoid valve control device (ECU109) according to the above-described embodiment determines that the closing of the solenoid valve (electromagnetic suction valve300) has succeeded when the change amount of the measurement signal output from the fuel pressure sensor (fuel pressure sensor126) is greater than the predetermined threshold value, and determines that the closing of the solenoid valve has failed when the change amount is equal to or smaller than the threshold value. As a result, it is possible to easily detect the closing of the solenoid valve, which is the motion of the valve body in response to the drive command. In addition, the control unit (microcomputer220) of the solenoid valve control device (ECU109) according to the above-described embodiment calculates the discharge amount by closing the solenoid valve (electromagnetic suction valve300) based on the change amount of the measurement signal output from the fuel pressure sensor (fuel pressure sensor126). As a result, it is possible to easily detect the discharge amount by the valve closing. The discharge amount by the valve closing corresponds to the motion of the valve body in response to the drive command. In addition, the control unit (microcomputer220) of the solenoid valve control device (ECU109) according to the above-described embodiment corrects the peak value of the drive current supplied to the solenoid valve to a value lower than the current setting value when determining that the closing of the solenoid valve (electromagnetic suction valve300) has succeeded, and corrects the peak value of the drive current supplied to the solenoid valve to a value higher than the current setting value when determining that the closing of the solenoid valve has failed. As a result, it is possible to drive the solenoid valve at the minimum current value, and it is possible to realize noise reduction and power saving. In addition, the control unit (microcomputer220) of the solenoid valve control device (ECU109) according to the above-described embodiment corrects the peak value of the drive current supplied to the solenoid valve to the value lower than the current setting value when the discharge amount of fuel by closing the solenoid valve (electromagnetic suction valve300) is greater than the predetermined value, and corrects the peak value of the drive current supplied to the solenoid valve to a value higher than the current setting value when the amount of fuel discharged by closing the solenoid valve is equal to or smaller than the predetermined value. Thus, it is possible to drive the solenoid valve at the minimum current value, and it is possible to realize noise reduction and power saving. In addition, the control unit (microcomputer220) of the solenoid valve control device (ECU109) according to the above-described embodiment determines whether or not closing of the solenoid valve (electromagnetic suction valve300) succeeds for each energization pulse of the solenoid valve or calculates the discharge amount by the valve closing for each energization pulse of the solenoid valve, based on the fuel pressure of the fuel rail (common rail129). As a result, it is possible to directly detect the valve closing success/failure of the solenoid valve as compared with a method of determining the valve closing success/failure of the solenoid valve simply based on whether the fuel pressure decreases or increases. In addition, the control unit (microcomputer220) of the solenoid valve control device (ECU109) according to the above-described embodiment is disposed on the downstream side of the fuel rail (common rail129), and when the fuel injection pulse applied to the fuel injection valve (fuel injection valve105) that injects fuel into the combustion chamber (combustion chamber121) of the engine is within the setting range, determines whether closing of the solenoid valve (electromagnetic suction valve300) succeeds based on the fuel pressure of the fuel rail, or calculates the discharge amount by closing the solenoid valve, and performs the solenoid valve control of controlling the valve closing or the valve opening operation of the solenoid valve based on the determination result or the calculation result. As a result, it is possible to detect whether or not the solenoid valve is closed or calculate the discharge amount by the valve closing in consideration of the fuel injection timing by the fuel injection valve. As a result, it is possible to improve the accuracy of the determination of whether or not closing of the solenoid valve has succeeded, or the calculation value of the discharge amount by closing the valve. In addition, since the solenoid valve control is performed based on whether or not the solenoid valve detected with high accuracy is closed or the discharge amount due to the valve closing calculated with high accuracy, the accuracy of the solenoid valve driving at the minimum current value can be improved. The control unit (microcomputer220) of the solenoid valve control device (ECU109) according to the above-described embodiment performs the solenoid valve control when determining that the injection pulse applied to the fuel injection valve (fuel injection valve105) does not interfere with the fuel discharge timing of the fuel pump (high-pressure fuel pump125). As a result, when the fuel pressure in the fuel rail changes, it is possible to detect whether the solenoid valve is successfully closed or calculate the discharge amount by closing the valve. As a result, it is possible to improve the accuracy of determination of whether or not closing of the solenoid valve has succeeded or calculation of the discharge amount by the valve closing. In addition, since the solenoid valve control is performed based on whether or not the solenoid valve detected with high accuracy is closed or the discharge amount due to the valve closing calculated with high accuracy, the accuracy of the solenoid valve driving at the minimum current value can be improved. In addition, the control unit (microcomputer220) of the solenoid valve control device (ECU109) according to the above-described embodiment performs a solenoid valve diagnosis process of determining whether or not closing of the solenoid valve (electromagnetic suction valve300) succeeds or calculating the discharge amount by closing the solenoid valve based on the fuel pressure of the fuel rail (common rail129) when the engine performs the idle operation. Accordingly, it is possible to reduce noise during an idle operation. In addition, the control unit (microcomputer220) of the solenoid valve control device (ECU109) according to the above-described embodiment performs a solenoid valve diagnosis process of determining whether or not closing of the solenoid valve (electromagnetic suction valve300) succeeds or calculating the discharge amount by closing the solenoid valve based on the fuel pressure of the fuel rail (common rail129) in a scene where the engine can be normally operated. As a result, since the solenoid valve diagnosis processing can be performed in a scene where the disturbance is small and the change in the fuel pressure and the discharge amount is small, it is possible to improve the accuracy of determination of the valve closing success or failure or calculation of the discharge amount by the valve closing. In addition, the solenoid valve control device (ECU109) according to the above-described embodiment controls opening and closing of the fuel injection valve in the internal combustion engine system including the fuel pump (high-pressure fuel pump125) including the plunger (plunger302) that moves up and down with the rotation of (pump drive cam301) to increase or decrease the volume of the pressurizing chamber (pressurizing chamber311), the solenoid valve (electromagnetic suction valve300) for sucking the fuel into the pressurizing chamber, and the discharge valve (discharge valve310) for discharging the fuel in the pressurizing chamber, the fuel rail (common rail129) for accumulating the fuel discharged by the fuel pump, and the fuel injection valve (fuel injection valve105) that injects the fuel to the combustion chamber (combustion chamber121) of the engine. The solenoid valve control device includes the control unit (microcomputer220) that determines whether or not closing of the fuel injection valve succeeds based on fuel pressure of the fuel rail, or calculates a discharge amount by closing the fuel injection valve based on the fuel pressure of the fuel rail. This makes it possible to detect the closing of the fuel injection valve, which is the motion of the valve body in response to the drive command, without adding a special circuit such as a low-pass filter circuit or an operational amplifier circuit. Hitherto, the solenoid valve control device according to the embodiment of the present invention has been described above including the operational effects thereof. However, the solenoid valve control device in the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the invention described in the claims. The above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and the above embodiments are not necessarily limited to a case including all the described configurations. Further, some components in one embodiment can be replaced with the components in another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Regarding some components in the embodiments, other components can be added, deleted, and replaced. For example, the above-described embodiments are applied to a normally open type solenoid valve in which the valve body is opened when no current flows in the solenoid and the valve body is closed when a current flows in the solenoid, as the solenoid valve. However, the electronic valve control device according to the present invention may be applied to a normally closed type solenoid valve in which a valve body is opened when a current flows through a solenoid and the valve body is closed when no current flows through the solenoid. REFERENCE SIGNS LIST 101internal combustion engine102piston103intake valve104exhaust valve105fuel injection valve109ECU110intake pipe111exhaust pipe121combustion chamber123fuel tank124low-pressure fuel pump125high-pressure fuel pump126fuel pressure sensor128exhaust cam129common rail201sensors202input signal203input circuit204A/D conversion unit205CPU206signal line210output circuit211control signal212actuators220microcomputer300electromagnetic suction valve301pump drive cam302plunger303valve body303aabutment piece304anchor305solenoid306fixing portion (magnetic core)307seat portion308stopper309first spring310discharge valve311pressurizing chamber315second spring321communication port322outflow port323casing325inflow port355relief valve | 73,063 |
11859585 | SPECIFIC DESCRIPTION FIG.1shows a perspective cut-away view of a part a high pressure fuel pump, or pumping unit,10for an internal combustion engine, particularly a compression-ignition internal combustion engine. The pumping unit10includes a pumping plunger (not shown) which extends through a plunger return spring12so that the longitudinal axis of the plunger is vertically aligned, in the orientation shown in the illustration. A pump housing14located above (in the illustration shown) the plunger return spring12projects through a mounting flange16for attaching the pumping unit10within the engine via bolts to be received within bolt holes18in the mounting flange. The pump housing10is provided with an electrical connector for enabling valves (not shown) forming part of the pumping unit10to be connected to the electronic control unit (ECU) (not shown) of the engine in a conventional manner. The electrical connector20projects perpendicularly from the pump housing14, relative to the axis of the pumping plunger, and is connected to the pump housing14by means of screws22(only one of which is shown) which engage with at least one, and preferably two, locating bushes (not shown inFIG.1). Referring also toFIG.2, the electrical connector20includes a generally tubular connector body24which is formed by overmoulding a thermoplastic material over first and second electrical connector pins,26,28respectively, each of which is of substantially cylindrical form. The external surface of the overmoulded connector body24defines a curved surface, having first and second flat wall regions30,32. The external shape of the connector body24may take many different shapes and/or configurations depending on the nature of the fuel system in which the electrical connector20is used and the available space for locating the electrical connector20. First and second locating pins34,36are provided in the curved surface of the connector body20. The locating pins34,36serve to retain the connector body20with the engine harness which forms the connection to the ECU. A side flange38forming part of the overmould for the connector body24, is located part way along the length of the connector body24. The side flange38provides a convenient attachment point for the connector body24to the engine. A further side flange40is just visible inFIG.2and is provided for the same purpose. Each flange38,40includes a locating bush as described previously (only one of which,42, is visible inFIG.2). The locating bushes42are made from steel (or another hard material) to prevent mounting bolts (not shown), which are to be received through the bushes, from deforming the material of the overmoulded flanges38,40. Referring also toFIG.3, the electrical connector20includes an open end20awhich defines a socket for a complementary connector (not shown) for the ECU, and a pump-attachment end20bwhich attaches to a connector forming part of the pump unit10. The first and second connector pins26,28extend into a recess44defined at the open end20aof the connector20so that the pins26,28are accessible for electrical contact with the ECU connector to complete the electrical connection to the ECU. It is one of the challenges with the electrical connector20to avoid leakage fuel from within the pump unit10passing along and around the electrical connector pins26,28, leaking from the pump-attachment end20bof the connector20towards the open end20aof the connector20, as this can cause damage to the electrical parts and/or affect pump performance. The present invention is configured to avoid this problem. In order to explain the benefits of the present invention, it is helpful to consider an electrical connector120of the state of the art, as shown inFIG.4. In the connector120inFIG.4, each of the connector pins126,128is substantially cylindrical but has a profiled cross-section along its length, with different regions of the pin having different diameters. For example, each electrical connector pin126,128is provided with first and second annular recesses150, spaced axially along the length of the connector pin126,128. It has been found, however, that a leakage path for fuel can occur along and around the connector pins126,128, in regions where the overmould does not make contact with the connector pins126,128adequately, leaving small gaps or pockets which are accessible to fuel leaking from the pump-attachment end120b. This can arise during the process of overmoulding when the thermoplastic material of the overmould shrinks on cooling, but does not shrink to seal against the connector pins126,128completely in all areas, leaving a leakage path for fuel between the pump-attachment end120band the open end120aof the connector body. Referring again toFIG.3, in the present invention, the inventors have realised that a different profile for the connector pins26,28results in the leakage problem being reduced or avoided altogether. InFIG.3, each connector pin26,28is identical and so only one of the pins will be described in detail. The connector pin28has a profiled cross-section along its length, having a first portion (referred to as the internal portion52) which is internal to the overmoulded connector body24and an external portion54(referred to as the connecting portion) which projects into the recess44of the open end20a. The internal portion52of the connector pin28has a substantially constant dimension in the form of a diameter towards the pump-attachment end20b, as represented by dimension D inFIG.3. In other embodiments, where the connector pin28has an alternative shape (for example, rectangular or square cross section, or substantially flat), the dimension need not be a diameter of the pin but may be a dimension of the cross section taken in a plane perpendicular to the axial length of the pin. The so-called internal portion52of the connector pin28includes a short projecting portion56that extends out of the connector body24at the pump-attachment end20b, where it maintains this same constant diameter D. In a region of the internal portion52which resides closer to the recess44, the diameter of the connector pin28varies along its length to provide the pin28with a series of axially spaced projections60and recesses62. In the example shown inFIG.3, there are four annular projections60along the length of the internal portion52of the connector pin28. The projections60represent those regions of the connector pin28having the greatest diameter. Adjacent ones of the projections60are separated by one of the recesses62, of which there are three, which represent those regions of the connector pin28having the smallest diameter. The radial extent of the projections60is therefore such that the diameter of the connector pin28in this region extends radially beyond the diameter, D, of the connector pin28in the constant diameter region of the internal portion52, including the projecting portion56. The recesses62are shaped so that in these regions the connector pin28has a reduced diameter when compared to the constant diameter region, D, of the internal portion52. There are two main benefits of changing the diameter of the connector pin28. Firstly, as mentioned previously, reducing the diameter of the connector pin28relative to the diameter, D, serves to minimise the leak path size if the overmoulding was to shrink away from, or to be poorly adhered to, the connector pin28. The second benefit is to provide a greater vertical sealing area on the pin, so that as the overmoulding moves during cooling there is a greater chance of some form of seal being maintained between the pin28and the overmould, again reducing the risk of leakage. In other embodiments (not shown) the depth of the recesses62may correspond to the constant diameter D of the internal portion52. Alternatively, the depth of the recesses62may be such that the connector pin28has a greater diameter in the recessed region62compared with the constant diameter region D (i.e. the recesses62are shallower than inFIG.3), although of course the diameter in these recessed regions62is still less than the diameter of the projections60. Referring also toFIG.5, each annular recess62has a depth, a, and each annular projection60has a height, a. Each projection60has an axially extending length, along the axial length of the connector pin28, equal to 1.5a. Each annular recess62has an axially extending length, a, extending along the axial length of the connector pin28so that the depth of the recess62is the same as its axial length. However, other combinations of dimensions for the axial lengths of the projections60and of the recesses62, and of the depths of the recesses62and the heights of the projections60, are also envisaged. Typically, the axial length, a, of each axial projection may be somewhere between a and 2.0a. The depth of each annular recess62may be increased, for example to 1.5a, whilst maintaining sealing benefits. In comparison with the known electrical connector120inFIG.4, one important feature of the electrical connector20inFIG.3is that the connector pins26,28are provided with a greater number of projections60, and with additional recesses62, along the length of the internal portion52of each pin. The increased number of projections60and recesses62gives an enhanced sealing capability for the overmould as the increased area of contact with the convoluted pin diameter increases the loading of the overmould material onto the pins. This has the effect that leakage of fuel between the pump-attachment end20bof the connector20and the socket end20aof the connector20is improved. Another important difference compared to the known electrical connector inFIG.4relates to the transition between the internal and external portions52,54of the pins26,28. The external portion54of the connector pin28extends into the socket end20awhere it has a substantially constant diameter, E, along its length. The diameter E of the connector pin28in this external portion54is slightly less than the diameter of the connector pin28in the internal portion52, but equally could be the same as the diameter D in the internal portion52(or greater) depending on the nature of the ECU connector with which it is to be coupled. Between the internal and external portions52,54of the connector pin28is a chambered portion70. The chamfered portion70allows the diameter of the connector pin28to transition smoothly between the internal52and external54portions of different diameter and provides a locating feature for the connector pin within the socket. An annular piece55is located inside the overmould24through which the connector pins26,28extend. The annular piece55defines an abutment surface for the chamfered portion70on each connector pin28. Furthermore, the region72of the connector pin28immediately adjacent to the chamfered portion70, between the chamfered portion70and immediately adjacent to an end one of the projections60a(far left hand projection inFIG.3), forms an increased diameter region F compared with the diameter D of the internal portion52(the constant diameter region). In this way, the increased diameter region72immediately adjacent to the chamfered portion70provides an additional “step” on the connector pin28, immediately before the end one of the projections60. The step height is typically 0.5a and the length is typically equal to a. This gradual increasing of the diameter—from the external portion54of the connector pin28(diameter E), to the chamfered portion70, to the increased diameter region of the step72(diameter F) and to the end-most one of the projections60—provides a further benefit for the overmoulding process with regard to reducing leakage along the connector pin28and into the open end20a, as there is an enhancement of the sealing area between the overmould material and the pins26,28in the stepped region. In comparison withFIG.4, it can be seen that this feature of the step72is not present and here the chamfered portion170connects directly with a projection160(greatest diameter region) of the internal portion of the connector pin28. The invention therefore relies on two inventive features to provides for an enhanced sealing capability between the overmould and the connector pins26,28: the provision of the increased diameter region72immediately adjacent to the chamfered region70and the provision of additional annular projections along the axial length of the internal portion52. In order to manufacture the electrical connector, the first and second connector pins26,28are mounted into a moulding machine and a molten plastic material is injected into the mould. Examples of materials which may be used for the moulding include thermosetting plastic materials, such as PPE, PPS, PBT and PEEK. During the injection process, the temperature and pressure of the injected material is varied to achieve the desired flow rate. The parts are removed from the moulding machine when the injection process is complete and they are then cooled. The sealing capability of the connector is then tested prior to use. When installed in the fuel system, the electrical connector20of the invention allows an electrical connection to be made between an engine control unit (ECU) and the pump unit10by plugging a connector (not shown) on a connecting cable from the ECU into the open end20aof the electrical connector20so that an electrical connection is made with the connector pins26,28in the recess44. This electrical connection allows the valves of the pump unit10to be controlled electrically by the ECU, whilst ensuring there is minimal or no fuel leakage along and around the connector pins26,28from the pump-attachment end20b. The reduced leakage results from the innovative manner in which the connector pins26,28are shaped to cooperate with the overmoulded connector body24with an enhanced sealing capability. It will be appreciated that various modifications may be made to the invention without departing from the scope of the invention as set out in the appended claims. | 14,035 |
11859586 | DETAILED DESCRIPTION In the following detailed description, certain specific details are set forth to provide a thorough understanding of various disclosed implementations and embodiments. However, one skilled in the relevant art will recognize that implementations and embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, and so forth. For the sake of continuity, and in the interest of conciseness, same or similar reference characters may be used for same or similar objects in multiple figures. As used herein, the term “coupled” or “coupled to” or “connected” or “connected to” “attached” or “attached to” may indicate establishing either a direct or indirect connection and is not limited to either unless expressly referenced as such. As used herein, fluids may refer to slurries, liquids, gases, and/or mixtures thereof. Embodiments disclosed herein are directed to a fuel injector for engines such as an internal combustion engine. More specifically, embodiments disclosed herein are directed to a fuel injector for directly injecting an air-fuel premixed fuel into a combustion chamber of an internal combustion engine. The fuel injector may draw high temperature and high-pressure air from the combustion chamber when fuel is injected. The different embodiments described herein may provide a fuel injector with an injector body having at least one mixing chamber allowing fuel (e.g., gasoline or diesel) and gas (e.g., hot air) to be mixed prior to delivery to the combustion chamber. A mixing chamber may be premixing tubes integrated and built into an injector tip of the fuel injector. In accordance with one or more embodiments, a fuel injector includes one or more nozzle assemblies. Each nozzle assembly may include a fuel channel, a premixing tube, and a port. The premixing tube may be used mix a fuel and air before injection into a combustion chamber of an internal combustion engine. In one or more embodiments, at least one premixing tube may be built into an injector tip of the fuel injector. Additionally, the fuel channel may feed fuel from a fuel chamber or tank into the premixing tube. Further, the port may be provided in an injector body of the fuel injector. The port may draw in air from an injection port of an interfacing chamber to mix with the fuel in the premixing tube to form an air-fuel premixed fuel. From the injector tip, the air-fuel premixed fuel may be injected into a combustion chamber of the internal combustion engine. In some embodiments, a control system, such as a computing system coupled to a controller (e.g., a processor), may be coupled to the fuel injector to control an operation of the fuel injector. The control system may include instructions or commands to operate the fuel injector automatically or a user may manually control the control system at a user interface. Conventional injection methods in the automobile industry typically requires costly equipment with an extensive layout and arrangement of pipes along the engine. Such conventional injection methods may also be more expensive because of the higher number of parts and components along with design and installation costs. Additionally, conventional injection methods lead to clogged fuel systems and engine carbon buildup that result in decrease engine performance, increased fuel consumption, a loss of power, and the need for expensive repairs. Advantageously, using the fuel injector disclosed herein for direct air-fuel premixed fuel injection operations, emissions from the combustion chamber may be dramatically reduced compared to conventionally used fuel injectors. Further, a configuration and arrangement of the fuel injector to directly inject an air-fuel premixed fuel into an internal combustion engine according to one or more embodiments described herein may provide a cost-effective alternative to conventional injection systems while providing lower emissions. For example, one or more embodiments described herein may control the amount of air-fuel premixed fuel injected in the combustion chamber so that a progression of chemical energy available in the combustion chamber is controlled and a pressure rise rate of the engine may be controlled. Overall, the fuel injector may minimize product engineering, risk associated with engine repairs, reduction of assembly time, hardware cost reduction, and weight and envelope reduction. Thus, the disclosed fluid injection methods using the fuel injector disclosed herein improves performance, decrease emissions, and reduces cost associated with conventional fluid injection operations in internal combustion engine. Embodiments are described herein merely as examples of useful applications, which are not limited to any specific details of the embodiments herein. Referring toFIG.1, a combustion system100in accordance with embodiments disclosed herein is illustrated. The combustion system100may be an internal combustion engine including at least one cylinder101formed within an engine body or engine block102. InFIG.1, only a portion of the engine block is shown, and only one cylinder in the engine block is shown, although an engine block may have several cylinders. The cylinder101may include a main chamber103. The main chamber103may be a combustion chamber of the combustion system100. Additionally, a cylinder head104may be mounted at a top of the cylinder101and forms an upper end of the main chamber103. A piston105may be arranged inside the cylinder101and forms a lower end of the main chamber103. The piston105moves up and down inside the cylinder101during an engine cycle, and the volume of the main chamber103changes with the position of the piston105. Further, the piston105may be connected to a crankshaft (not shown) by a connecting rod106. The crankshaft may convert the reciprocating motion of the piston105into rotary motion, as is well known in the art. In one or more embodiments, the cylinder head104may include a tunnel107terminating at an injection port108of the main chamber103. A fuel injector200according to embodiments of the present disclosure, as described inFIGS.2-7, may be mounted in the cylinder head104via the tunnel107. A clamp117may removably fix the fuel injector200to the cylinder head104. The clamp117may be disposed on a top of the fuel injector200and be attached to the cylinder head104to maintain a position of the fuel injector200in the tunnel107. The fuel injector200may be aligned and coaxial or angled with respect to a cylinder axis of the cylinder head104. In one example, installation of the fuel injector200to the cylinder head104includes forming one or more nozzle assemblies. Each nozzle assembly may include a fuel channel, a premixing tube, and a port formed inside a tip of the fuel injector200, as described in detail below. The fuel injector200may be inserted into the tunnel107, and a threaded connection or snap-fit may be made between the fuel injector200and the injection port108of the main chamber103, such that the one or more nozzle assemblies may be in a position where an orifice of the premixing tube(s) are in fluid communication to the main chamber103. With the fuel injector200installed, the fuel injector200may be used for a compression ignition operation in the engine block102such that there is no spark plug or external ignition device. The compression ignition operation allows for fuel to auto ignite when a cylinder pressure and temperature during compression exceeds an autoignition threshold of the fuel. Still referring toFIG.1, the cylinder head104may optionally include a second fuel injector200aused in combination with the fuel injector200. As shown, the cylinder head104may include at least one intake passage119terminating in a second intake port110. A second fuel injector200amay be positioned within the intake passage119. The second fuel injector200amay be a similar fuel injector as the fuel injector200. The cylinder head104may include at least one exhaust passage111having in an exhaust port112. Additionally, an intake port110may include an intake valve113to control opening and closing of the intake port110. Air may be drawn into the injector200when the injector200is injecting fuel. Although not shown, the main chamber103and the intake passage119may be connected to a source of air in a conventional manner. The air in the main chamber103and the intake passage119may be ambient air or a mixture of ambient air and recirculated exhaust gases. An exhaust valve114may be arranged to control opening and closing of the exhaust port112. When the exhaust port112is open, exhaust gases can be pushed out of the main chamber103into the exhaust passage111. A tunnel107, an intake passage119, an exhaust passage111and associated components (e.g., valves113,114and fuel injectors200,200a) may be provided in the cylinder head104for each cylinder in the combustion system100, such as in the arrangement shown inFIG.1for the cylinder101. In one or more embodiments, the fuel injector(s)200,200amay be used to directly inject a mixture of fuel and air into the main chamber103. The air flowing through the main chamber103and the intake passage119may be drawn into the premixing tube of each nozzle assembly via the port of each nozzle assembly. Additionally, fuel may enter the premixing tube of each nozzle assembly via the fuel channel of each nozzle assembly. In the premixing tube, the air and fuel may mix forming an air-fuel premixed fuel to be delivered, via injection, to the main chamber103. In one example, the air-fuel premixed fuel may have an air to fuel ratio equal to or more than 2 such that the air-fuel premixed fuel is lean for lower emissions. The fuel injector(s)200,200amay be fluidly connected to a fuel line115, which is in communication with a fuel supply116. A control system, such as an engine control unit, may control an opening and closing of the fuel injector(s)200,200ato deliver the air-fuel premixed fuel into the main chamber103at desired times during an engine cycle. In some embodiments, a cable (not shown), such as an electrical or hydraulic power cable, may be coupled the fuel injector(s)200,200a. The cable may provide power to the fuel injector(s)200,200afrom a power source (not shown). Additionally, the cable may be connected to a control system such a panel (e.g., switchboards/user interface) having a computing system coupled to a controller (e.g., a processor) to control the fuel injector(s)200,200a. The control system may include instructions or commands to operate the fuel injector(s)200,200aautomatically or a user may manually control the control system at the panel. It is further envisioned control system may be connected to an office via a satellite such that a user may remote monitor conditions and send commands to the fuel injector(s)200,200a. If leaks and performance issues are found, an alert may be sent to the control system to adjust or turn off the fuel injector(s)200,200amanually or automatically. Now referring toFIG.2A, a close-up of the fuel injector200taken from the dashed box2ofFIG.1is illustrated. More specifically, the dashed box2shows an injection end of the fuel injector200, including a tip208of the fuel injector200in accordance with embodiments disclosed herein. The fuel injector200may include an injector body201having a fuel chamber202formed therein. The fuel chamber202may be a bore formed in the injector body201. The fuel chamber202may be fluidly coupled to the fuel line (see115inFIG.1) such that the fuel supply (see116inFIG.1) may feed fuel into the fuel chamber202. Additionally, at an end distal from the fuel supply, the fuel chamber202may have a conical end204. The conical end204may include an inner conical surface204a. Further, a needle ball (203a,203b) may be provided within the fuel chamber202, where fuel may be provided in the annulus formed between the fuel chamber bore and the needle ball. The needle ball may include a ball end203aattached to a rod203b. The ball end203amay be adjacent to the conical end204such that the ball end203amay be fitted within the inner conical surface204a. When the needle ball (203a,203b) is moved axially relative to the inner conical surface204a, the amount of fuel flowing from the fuel chamber202into the conical end204may be varied. As shown inFIG.2A, the needle ball (203a,203b) may be in a closed position, where a perimeter of the ball end203acontacts an entire inner diameter of the inner conical surface204a. In the closed position, the ball end203amay seal the conical end204, such that no fuel from the fuel chamber202enters the conical end204. InFIG.2B, the needle ball (203a,203b) is illustrated in an open position. In the open position, the ball end203amay be axially spaced apart from the inner conical surface204asuch that fuel from the fuel chamber202enters the conical end204. In some embodiments, the fuel injector200may be calibrated to automatically move the needle ball (203a,203b) back and forth from the closed position to the open position to allow a calibrated amount fuel into the conical end204. Still referring toFIG.2A, in one or more embodiments, one or more nozzle assemblies209of the fuel injector200may be formed around the conical end204of the tip208. Each nozzle assembly209may include a fuel channel205, a premixing tube206, and a port207formed within the injector body201. The fuel channel205may be provided in the injector body201extending from the fuel chamber202. The fuel channel205may fluidly couple the fuel chamber202to the premixing tube206provided in the injector body201. In some embodiments, the fuel channel205may be coaxial with the premixing tube206. The port207may extend from the outer surface204bof the tip208through the injector body201to the premixing tub206. In some embodiments, the port207may intersect the premixing tube206at substantially the same location that the fuel channel205intersects the premixing tube206. When the outer surface204bof the tip208is interfacing the main chamber of an engine cylinder, the port may allow air from the main chamber (see103FIG.1) to enter the premixing tube206. From the port207and the fuel channel205, air and fuel may mix within the premixing tube206to form an air-fuel premixed fuel. With the air-fuel premixed fuel formed, an end of the premixing tube206may be an orifice for the air-fuel premixed fuel to exit the premixing tube206and be injected into the main chamber of a cylinder (see101inFIG.1). The orifice may be a valve covered orifice to control the amount of injected air-fuel premixed fuel, e.g., to prevent any additional air-fuel premixed fuel dripping into the main chamber from the premixing tube206after injection operations to avoid particulate emissions. According to embodiments of the present disclosure, the orifice of a premixing tube206may be formed around an outer circumference of the injection end of the fuel injector200, such that the premixing tube(s)206extend from fuel channel205and port207to the outer circumference of the injector body200, as shown inFIGS.2A and2B. When premixing tubes206are formed to exit around the outer circumference of a fuel injector tip208, the fuel injector200may be positioned in cylinder head tunnel (107inFIG.1) and injection port (108inFIG.1) such that the tip208may protrude enough into the adjacent main chamber (e.g.,101inFIG.1) to allow for the exiting air-fuel premixed fuel to enter into the main chamber, while preventing the internal components (e.g., the needle ball203a,203b) of the fuel injector200from protruding into the main chamber. In such embodiments, the air-fuel premixed fuel may be directed into an adjacent main chamber of a cylinder around the outer circumference of the fuel injector tip208. In other embodiments, such as described below with reference toFIG.6, premixing tubes206may exit an end204bof the tip208, and the end204bof the tip208may be flush or aligned with the main chamber wall, such that the tip208does not protrude into the main chamber. In some embodiments, each port207may be a flat tube (e.g., having a rectangular cross-sectional profile), which may increase heat transfer from the air coming into the premixing tube206during fuel injection and combustion. By increasing heat transfer, the air may be cooled to avoid autoignition from occurring in the fuel injector200. If autoignition occurs, air and fuel may not mix as the fuel is ignited and the fuel injector200may be damaged. Additionally, the tip208of the fuel injector200may have a diameter large enough that each port207of the multiple nozzle assemblies209may be spaced apart from each other. By spacing the ports207apart from each other, the ports207may draw air from the injection port108of the main chamber (see103inFIG.1) from multiple locations rather than a central location. With air drawn in from multiple locations, the fuel injector200may have improved air utilization in the main chamber during the injection and combustion process. Further, in some embodiments, the outer surface204bof the injector tip208may have a conical shape, such as shown inFIGS.2A and2B, to improve air flow into the ports207by drawing more air into the port207. The conical shape of the outer conical surface204bmay trap and recirculate air into the ports207. Now referring toFIGS.3-5, various cross-sectional views of the fuel injector200taken fromFIG.2Aare illustrated. Referring toFIG.3, a cross-sectional view taken along dashed line3-3of the fuel injector200fromFIG.2Ais illustrated. The injector body201may be a cylinder extending axially from a distal end201ato a nozzle end201b. The fuel chamber202may be formed from a bore within the injector body201. Further, the injector body201may insulate the fuel chamber202. In one or more embodiments, the fuel channel205and the premixing tube206may be coaxial about an axis A. The axis A may be angled from the fuel chamber202central axis. Further, the port207may be perpendicular (or other angle) to the axis A. Referring toFIG.4, a cross-sectional view taken along dashed line4-4of the fuel injector200fromFIG.2Ais illustrated. The injector body201may have a circular cross-sectional profile. Additionally, each of the fuel channels205may have a cylindrical shape. As shown, the needle ball203amay be centered in the injector tip cone204a. Referring toFIG.5, a cross-sectional view taken along dashed line5-5of the fuel injector200fromFIG.2Ais illustrated. Each of the ports207may be flat tubes that intersect the premixing tubes206. The ports207may have a generally rectangular cross-sectional profile, including a width207aand a thickness207b. Further, each of the premixing tubes206may have a generally cylindrical shape. Now referring toFIG.6, a close-up of a premixing tube206is illustrated. The premixing tube206may extend outwardly from the port207and the fuel channel205to exit at an end204bsurface of the fuel injector tip. In such embodiments, the tip208of the fuel injector200may be flush or aligned with the injection port (108inFIG.1) formed in the main chamber (103inFIG.1), such that internal components of the fuel injector200do not protrude into the main chamber103(as shown inFIG.1). By not extending into the main chamber, heat transfer from the fuel injector200to the cylinder head (104inFIG.1) may be improved, which may reduce the temperature of the fuel injector200, and thus reduce the chance of having an autoignition event occur therein. In a non-limiting example, the premixing tube206may have a diameter larger than a diameter of the fuel channel205and a thickness of the port207. Additionally, the thickness of the port207may be larger than the diameter of the fuel channel205. By having the premixing tube206larger than the fuel channel205and the port207, the increased diameter creates a low-pressure wake zone so that air may be drawn into the fuel flow; then, mixing naturally occurs from high velocity fuel and air flow meeting in the premixing tube206. Further, with fuel pressure higher than gas pressure in chamber103and flow direction of fuel in205, the premixing tube206may prevent flow back into the fuel channel205and the port207. In one or more embodiments, air being drawn into the premixing tube206may be controlled by a fuel pressure from fuel entering the premixing tube206. Additionally, the ball end (see203ainFIG.2A) of the needle ball may control the fuel entering the fuel channel205and stop a dripping of the fuel from the conical end204. For example, the ball end of needle ball may be flush against the inner conical surface204ato stop fuel from entering the fuel channel205. By controlling fuel pressure, a velocity of the fuel flow in the fuel channel205may be affected to create a low-pressure zone in an intersection between the fuel channel205, the premixing tube206, and the port207. The premixing tube206may extend from an intersection between the fuel channel205and the port207to terminate at an orifice212flush with the outer conical surface204b, which may interface with the main chamber103in an engine cylinder. From the premixing tube206, the air-fuel premixed fuel may be injected into the main chamber103through the orifice212. FIG.7is a flowchart showing a method of a fluid injection using the fuel injector200ofFIGS.1-6. One or more blocks inFIG.7may be performed by one or more components (e.g., a computing system coupled to a controller in communication with the fuel injector200) as described inFIGS.1-6. For example, a non-transitory computer readable medium may store instructions on a memory coupled to a processor such that the instructions include functionality for operating the fuel injector200. While the various blocks inFIG.7are presented and described sequentially, one of ordinary skill in the art will appreciate that some or all of the blocks may be executed in different orders, may be combined or omitted, and some or all of the blocks may be executed in parallel. Furthermore, the blocks may be performed actively or passively. In Block700, a fuel injector is fluidly coupled a combustion chamber of the engine block. The fuel injector may be clamped to the body of the engine block, for example. Additionally, the method includes positioning the fuel injector to have an orifice of each premixing tube be flush against the combustion chamber such that the premixing tube does not extend into the combustion chamber, as shown in Block701. In Block702, with the fuel injector in place, the fuel line may provide fuel from a fuel supply to the fuel injector. Additionally, the fuel enters the fuel chamber of the fuel injector directly from the fuel line. In Block703, with fuel in the fuel chamber, fuel is sprayed from the fuel chamber through a fuel channel of the fuel injector into the premixing tube. In addition, the controller may include controls or commands to operate the amount of fuel and when the fuel is being sprayed through the fuel channel via a needle ball, as shown in Block704. For example, the needle ball may axially move back and forth to control the amount of fuel leaving the fuel chamber. It is further envisioned that the needle ball may stop a dripping of the fuel. In Block705, air may be drawn in the ports via a conical shape of the combustion chamber or an injection port. The conical shape of the combustion chamber may trap and recirculate air into the ports. From the ports, the air flow may be directed into the premixing tube, as shown in Block706. Additionally, the combustion chamber or the intake passage may have a conical shape at the ports to provide better air flow and utilization for the ports. Further, when the ports are flat tubes, the air may be cooled before entering the premixing tube, as shown in Block707. In Block708, with the air being directed into the premixing tube and the fuel being spraying into the premixing tube, the air and fuel may mix to form an air-fuel premixed fuel in the premixing tube. In some embodiments, the premixing tube may have internal conduits to control a mixing of the air and the fuel. The air-fuel premixed fuel may have an air to fuel ratio equal to or more than 2, such that the air-fuel premixed fuel is lean for lower emissions. In Block709, a mixture ratio of the air and fuel in the premixing tube may be formed to a value equal to or more than 2 such that the air-fuel premixed fuel is lean for lower emissions. Based on a calibration of the engine block, the controller may determine if a required volume of fluids has been injected into the premixing tube to form the air-fuel premixed fuel at the mixture ratio, as shown in Block710. For example, using the mixture ratio measurement, an amount of air and fuel being injected into the premixing tube from the port and the fuel channel of the fuel injector may be determined. If the required volume of fluids has been reached, the controller may proceed to instruct the fuel injector to inject the air-fuel premixed fuel into the combustion chamber from the premixing tube, as shown in Block711, such that the engine may perform combustion operations. However, if the required volume of fluids has not been reached, in Block712, the controller may continue or adjust the amount of air and/or fuel flow entering the premixing tube until the mixture ratio reaches the desired requirement. For example, the controller may adjust a suction rate or spray rate of the fuel injector to suck air into the ports or spraying fuel through the fuel channel. Implementations herein for operating the fuel injector200may be implemented on a computing system coupled to a controller in communication with the various components of the fuel injector200. Any combination of mobile, desktop, server, router, switch, embedded device, or other types of hardware may be used with the submersible pump system800. For example, as shown inFIG.8, the computing system800may include one or more computer processors802, non-persistent storage804(e.g., volatile memory, such as random access memory (RAM), cache memory), persistent storage806(e.g., a hard disk, an optical drive such as a compact disk (CD) drive or digital versatile disk (DVD) drive, a flash memory, etc.), a communication interface812(e.g., Bluetooth interface, infrared interface, network interface, optical interface, etc.), and numerous other elements and functionalities. It is further envisioned that software instructions in a form of computer readable program code to perform embodiments of the disclosure may be stored, in whole or in part, temporarily or permanently, on a non-transitory computer readable medium such as a CD, DVD, storage device, a diskette, a tape, flash memory, physical memory, or any other computer readable storage medium. For example, the software instructions may correspond to computer readable program code that, when executed by a processor(s), is configured to perform one or more embodiments of the disclosure. The computing system800may also include one or more input devices810, such as a touchscreen, keyboard, mouse, microphone, touchpad, electronic pen, or any other type of input device. Additionally, the computing system800may include one or more output devices808, such as a screen (e.g., a liquid crystal display (LCD), a plasma display, touchscreen, cathode ray tube (CRT) monitor, projector, or other display device), a printer, external storage, or any other output device. One or more of the output devices may be the same or different from the input device(s). The input and output device(s) may be locally or remotely connected to the computer processor(s)802, non-persistent storage804, and persistent storage806. Many different types of computing systems exist, and the input and output device(s) may take other forms. The computing system800ofFIG.8may include functionality to present raw and/or processed data, such as results of comparisons and other processing. For example, presenting data may be accomplished through various presenting methods. Specifically, data may be presented through a user interface provided by a computing device. The user interface may include a GUI that displays information on a display device, such as a computer monitor or a touchscreen on a handheld computer device. The GUI may include various GUI widgets that organize what data is shown as well as how data is presented to a user. Furthermore, the GUI may present data directly to the user, e.g., data presented as actual data values through text, or rendered by the computing device into a visual representation of the data, such as through visualizing a data model. For example, a GUI may first obtain a notification from a software application requesting that a particular data object be presented within the GUI. Next, the GUI may determine a data object type associated with the data object, e.g., by obtaining data from a data attribute within the data object that identifies the data object type. Then, the GUI may determine any rules designated for displaying that data object type, e.g., rules specified by a software framework for a data object class or according to any local parameters defined by the GUI for presenting that data object type. Finally, the GUI may obtain data values from the data object and render a visual representation of the data values within a display device according to the designated rules for that data object type. Data may also be presented through various audio methods. Data may be rendered into an audio format and presented as sound through one or more speakers operably connected to a computing device. Data may also be presented to a user through haptic methods. For example, haptic methods may include vibrations or other physical signals generated by the computing system. For example, data may be presented to a user using a vibration generated by a handheld computer device with a predefined duration and intensity of the vibration to communicate the data. While the method and apparatus have been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope as disclosed herein. Accordingly, the scope should be limited only by the attached claims. | 30,313 |
11859587 | DETAILED DESCRIPTION OF THE DRAWINGS The internal combustion engine2comprises a plurality of cylinders, of which in the present case only one cylinder4is shown. In the variant shown inFIG.1, the cylinder4corresponds to a so-called starting cylinder which is fired first when starting the internal combustion engine2. Accordingly, the cylinder4can also be referred to as a starting cylinder. In a cylinder interior of the cylinder4there is arranged a piston7which is assigned to the cylinder4and which, together with the cylinder4, delimits a combustion chamber22. The piston7is coupled to a crankshaft5of the internal combustion engine2via a connecting rod23. The crankshaft5can be coupled via a clutch (not shown further here) of the motor vehicle1to a transmission (likewise not shown further) of the motor vehicle1. The transmission is coupled to drive wheels (not shown further here) of the motor vehicle1. Working gas3can be introduced into the combustion chamber22and residual gas in the form of exhaust gas can be discharged from the combustion chamber22via respective gas exchange valves11,12which can be assigned to the cylinder4. Working gas3in the form of air can flow into the combustion chamber22via the gas exchange valve11formed as an inlet valve, insofar as the gas exchange valve11is in an open position. Via the gas exchange valve12which is formed as an outlet valve, the residual gas can flow out of the combustion chamber22and be supplied to exhaust-gas after-treatment systems (not shown further here) of the internal combustion engine2, which can include, for example, a catalytic converter and a particulate filter. The gas exchange valves11,12can be actuated via respective camshafts which are coupled to the crankshaft5. Thus, one of these camshafts can be formed as an inlet camshaft24for actuating the gas exchange valve11configured as an inlet valve. Another of these camshafts can be formed as an outlet camshaft25for actuating the gas exchange valve12configured as an outlet valve. The gas exchange valves11,12can also be actuated via a valve control device13. The valve control device13serves to set the valve strokes of the respective gas exchange valves11,12, which are assigned to the cylinder4which is fired first when starting the internal combustion engine, in order to introduce the working gas3into the cylinder4which is fired first. For this purpose, the valve control device13comprises an inlet valve controller20and an outlet valve controller21. Using the inlet valve controller20, the valve stroke of the inlet valve (gas exchange valve11) can be set additionally or alternatively to the inlet camshaft24in order to introduce the working gas3into the cylinder4. Using the outlet valve controller21, the valve stroke of the gas exchange valve12(outlet valve) can be set additionally or alternatively to the outlet camshaft25, in order to introduce the working gas3into the cylinder4. Opening both the inlet valve (gas exchange valve11) and the outlet valve (gas exchange valve12) allows scavenging of the combustion chamber22to be effected, with the result that the predetermined quantity of working gas3can be introduced into the cylinder4, and thus into the combustion chamber22, with reduction of a flow resistance. The motor vehicle1is in the present case configured as a hybrid vehicle and comprises an electric motor6which is coupled to the crankshaft5. The electric motor6can, for example, take the form of a motor generator, with the result that both a motor mode and a generator mode of the electric motor6are possible. Just like the drive wheels, the crankshaft5can be driven using the electric motor6. To control the electric motor6, the motor vehicle1comprises an electronic control device16which is designed to control the electric motor6in such a way that the electric motor6drives the crankshaft5of the deactivated internal combustion engine2and thereby moves the piston7, which is coupled to the crankshaft5and assigned to the cylinder4which is fired first. As a result, for subsequent starting of the deactivated internal combustion engine2, a predetermined quantity of the working gas3is introduced into the cylinder4which is fired first when starting the internal combustion engine2. The predetermined quantity of the working gas3is in the present case introduced into the combustion chamber22during an engine rundown of the internal combustion engine2. The electronic control device16is designed to control a starter17of the internal combustion engine2in such a way that the starting of the internal combustion engine2occurs in that, using the starter17, an ignition of a mixture8, which is formed in the combustion chamber22and comprises the predetermined quantity of working gas3and a predetermined quantity of fuel9, is effected within the cylinder4which is fired first. The starter17comprises in the present case an injector18and an igniter19. Using the injector18, the predetermined quantity of fuel9can, for example, be directly introduced into the combustion chamber22. For this purpose, the injector18can comprise an injector. Using the igniter19, the mixture8can be ignited and, as a result, the internal combustion engine2can be activated in that, on account of the ignition of the mixture8, the crankshaft5is rotated in an operating direction of rotation15illustrated by an arrow. Subsequent intermittent firing of the cylinders of the internal combustion engine2causes the crankshaft5to be accelerated further until, for example, the idle rotational speed of the internal combustion engine2has been reached. The crankshaft5can be driven using the electric motor at a rotational speed10which is less than an idle rotational speed of the internal combustion engine2. Alternatively, the crankshaft5can also be accelerated from its standstill using the electric motor6and, after the predetermined quantity of working gas3has been introduced into the cylinder4which is fired first, can be set into standstill again. Furthermore, the crankshaft5can be rotated from its standstill using the electric motor in a direction14which is oriented opposite to the operating direction of rotation15of the crankshaft5with the internal combustion engine2activated. Moreover, the crankshaft5can be coupled to the drive wheels of the motor vehicle1in a torque-transmitting manner while the crankshaft5is driven by the electric motor6. The piston7can be moved in a defined manner by the crankshaft5being driven using the electric motor6, and in addition the scavenging of the combustion chamber22with the working gas3can be effected by opening the gas exchange valves11,12. This can ensure that, during subsequent starting of the internal combustion engine2, little residual gas is contained in the combustion chamber22and a defined quantity of fresh air is available for starting the internal combustion engine2by igniting the mixture8. FIG.2shows a diagram on whose ordinate axis a rotational speed n is plotted and whose abscissa axis a time t is plotted. The diagram shows qualitatively different rotational speed profiles26,27,28,29of the crankshaft5which can result when starting the internal combustion engine2. It can be seen inFIG.2that the rotational speed profiles26,27are situated tightly together and have a very similar profile, this indicating good reproducibility of respective starting operations of the internal combustion engine2on which the rotational speed profiles26,27are based. In order to achieve the rotational speed profiles26,27, the predetermined quantity of working gas3has been introduced, with the internal combustion engine2deactivated, into the cylinder4which is fired first when starting the internal combustion engine2. By contrast thereto, the further rotational speed profiles28,29show that poor reproducibility is achieved when the introduction of the predetermined quantity of the working gas3into the cylinder4ceases. The rotational speed profiles26,27thus result with an optimized filling of the starting cylinder (cylinder4) with the predetermined quantity of working gas3, whereas the unfavorable rotational speed profiles28,29result with non-optimized filling of the cylinder4. LIST OF REFERENCE SIGNS 1Motor vehicle2Internal combustion engine3Working gas4Cylinder5Crankshaft6Electric motor7Piston8Mixture9Quantity of fuel10Rotational speed11Gas exchange valve12Gas exchange valve13Valve control device14Direction15Operating direction of rotation16Electronic control device17Starter18Injector19Igniter20Inlet valve controller21Outlet valve controller22Combustion chamber23Connecting rod24Inlet camshaft25Outlet camshaft26Rotational speed profile27Rotational speed profile28Rotational speed profile29Rotational speed profilen Rotational speedt Time | 8,759 |
11859588 | DETAILED DESCRIPTION An embodiment of the present invention is described below on the basis of the drawings.FIG.1is an explanatory diagram schematically depicting an outline of a system configuration of an internal combustion engine1to which the present invention is applied. The internal combustion engine1is, for example, a multi-cylinder spark ignition gasoline engine, and is mounted as a drive source in an automobile or another vehicle. The internal combustion engine1may be a diesel engine. The internal combustion engine1has a fuel injection valve (not shown). An amount of fuel injected through the fuel injection valve, a fuel injection timing of the fuel injection valve, a pressure of fuel supplied to the fuel injection valve, and the like are optimally controlled by a control unit21, which will be described later. The internal combustion engine1has a starter motor2serving as an electric motor. The starter motor2rotates a crankshaft (not shown) of the stopped internal combustion engine1to start (cranking) the internal combustion engine1. The starter motor2is controlled by a control unit21, described hereinafter. Drive force of the internal combustion engine1is transmitted via a torque converter3and a clutch4to a continuously variable transmission (CVT)5serving as a transmission, and the drive force transmitted to the CVT5is transmitted via a final gear6to drive wheels7of the vehicle. That is, the internal combustion engine1transmits, for example, rotation of the crankshaft (not shown) as drive force to the drive wheels7of the vehicle. The clutch4is positioned between the torque converter3and the CVT5, and is engaged when driving torque from the internal combustion engine1can be transmitted to the drive wheels7. That is, the clutch4is disposed on a motive power transmission path through which the drive force of the internal combustion engine1is transmitted to the drive wheels7. The operation of engaging/disengaging the clutch4is performed on the basis of a control command from the control unit21(described hereinafter). The clutch4is disengaged during, for example, a coasting stop (described hereinafter) or the like. The CVT5has a primary pulley8on an input side, a secondary pulley9on an output side, and a belt10that transmits rotation of the primary pulley8to the secondary pulley9. The CVT5, for example, uses oil pressure to change widths of V grooves (not shown) in the primary pulley8and the secondary pulley9around which the belt10is wound, changes a contact radius between the belt10and the primary pulley8and secondary pulley9, and continuously changes a transmission ratio. The CVT5is used as the transmission, but it is also possible to use a stepped automatic transmission instead of the CVT5. In this case, the clutch4would be configured using a plurality of friction engagement elements in the stepped automatic transmission. The control unit21receives detection signals from a crank angle sensor22that detects a crank angle of the crankshaft2, an accelerator position sensor23that detects an amount by which an accelerator pedal (not shown) is depressed, a vehicle speed sensor24that detects speed of the vehicle, a brake sensor25that detects an amount by which a brake pedal (not shown) is depressed, a catalyst temperature sensor26that detects a catalyst temperature of an exhaust purification catalyst (not shown) provided in an exhaust passage (not shown) of the internal combustion engine1, a pressure sensor27that detects a pressure (air pressure) in the collector4, and other various sensors. The control unit21calculates load (engine load) required by the internal combustion engine1using the detection value of the accelerator position sensor23. The control unit21is capable of detecting a state of charge (SOC), which is a ratio of a remaining charge to a charge capacity of an onboard battery (not shown). In other words, the control unit21is equivalent to a battery SOC detection part. The crank angle sensor22is capable of detecting an engine speed (number of engine rotations) of the internal combustion engine1. When predetermined automatic stop conditions are met while the vehicle is traveling or stopped, the fuel supply is stopped and the internal combustion engine1stops automatically. The internal combustion engine1then restarts when a predetermined automatic restart condition is met during the automatic stop. In other words, the control unit21automatically stops the internal combustion engine1when the predetermined automatic stop conditions are met, and automatically restarts the internal combustion engine1when a predetermined automatic restart condition is met. The automatic stop conditions of the internal combustion engine1are, for example, that the accelerator pedal is not depressed, that the battery SOC of the onboard battery is greater than a predetermined battery threshold SOCth, that the catalyst temperature of the exhaust purification catalyst is higher than a predetermined first catalyst temperature threshold T1, and the like. The internal combustion engine1automatically stops when these automatic stop conditions have all been met. In other words, the control unit21automatically stops the internal combustion engine1when these automatic stop conditions have all been met while the internal combustion engine1is running. That is, the control unit21is equivalent to a first control part that stops fuel injection to automatically stop the internal combustion engine1when predetermined automatic stop conditions are met. Conditions for automatically restarting the internal combustion engine1are, for example, that the accelerator pedal is depressed, that the battery SOC of the onboard battery is equal to or less than the predetermined battery threshold SOCth, that the catalyst temperature of the exhaust purification catalyst is equal to or less than the predetermined first catalyst temperature threshold T1, and the like. The internal combustion engine1restarts when a restart request has been made during an automatic stop. In other words, the control unit21restarts the internal combustion engine1when any of these automatic restart conditions is met during an automatic stop of the internal combustion engine1. For example, the automatically stopped internal combustion engine1restarts when the battery SOC of the onboard battery becomes equal to or less than battery threshold SOCth, which is a predetermined value. Examples of an automatic stop of the internal combustion engine1include an idle stop, a “coast stop,” and a “sailing stop.” An idle stop is carried out when automatic stop conditions such as, for example, those described above are met while the vehicle has temporarily stopped. The idle stop is canceled when any automatic restart condition such as, for example, those described above is met. A coast stop is carried out when automatic stop conditions such as, for example, those described above are met while the vehicle is traveling. The coast stop is canceled when any automatic restart condition such as, for example, those described above is met. A coast stop is an automatic stopping of the internal combustion engine1during deceleration with the brake pedal depressed at, for example, a low vehicle speed. A sailing stop is carried out when automatic stop conditions such as, for example, those described above are met while the vehicle is traveling. The sailing stop is canceled when any automatic restart condition such as, for example, those described above is met. A sailing stop is an automatic stopping of the internal combustion engine1during inertia traveling with the brake pedal not depressed at, for example, a medium to high vehicle speed. When a request to restart the internal combustion engine1has been made during a decrease in the engine speed of the internal combustion engine1due to an automatic stop, the control unit21starts (causes combustion to occur in) the internal combustion engine1by resuming fuel injection if the engine speed of the internal combustion engine1is equal to or greater than a predetermined combustion recoverable rotational speed threshold R1(rotational speed threshold) at which restarting is possible only by fuel injection, and rotatably drives the crankshaft2using the alternator6to start (crank) the internal combustion engine1if the engine speed of the internal combustion engine1is lower than the combustion recoverable rotational speed threshold R1. Furthermore, when a restart request has been made in a brake ON state in which the brake pedal is depressed, the control unit21does not start the internal combustion engine1by resuming fuel injection, but rather causes the internal combustion engine1to rotate and using the starter motor2, thus starting the engine, after the engine speed has reached “0.” That is, the control unit21is equivalent to a second control part. The combustion recoverable rotational speed threshold R1is set by taking into account a time difference between a timing at which a fuel injection start command for the internal combustion engine1during an automatic stop is issued and a timing at which fuel is ignited in the cylinders (a timing of first combustion after fuel injection is resumed). That is, the combustion recoverable rotational speed threshold R1is set so that the engine speed at the timing of the first combustion after fuel injection is resumed does not fall below the rotational speed at which the internal combustion engine1can be started by resuming fuel injection, taking into account the extent of decrease in the engine speed from the timing at which the fuel injection start command is issued until the timing at which fuel is ignited in the cylinders. The combustion recoverable rotational speed threshold R1is set according to the deceleration rate of the internal combustion engine1, and is, e.g., about 600 rpm. When the automatically stopped internal combustion engine1is started (combustion is started) by a resuming of fuel injection, there is a time difference between the timing at which the fuel injection start command is issued and the timing at which fuel is ignited in the cylinders. That is, the timing of a combustion start in the internal combustion engine1is delayed from the timing at which the fuel injection start command is issued, which is because the fuel is supplied to a cylinder in an intake stroke after the fuel injection start command is issued, and the fuel in this cylinder is ignited (combusted) through a compression stroke. When the automatically stopped internal combustion engine1is started (combustion is started) by a resuming of fuel injection and the deceleration rate of the vehicle increases due to further depression of the brake pedal at the timing at which the fuel injection start command is issued, there is a possibility that the engine speed will decrease significantly before the timing of ignition in the cylinder in which the fuel combusts first. When the deceleration rate of the vehicle increases due to the brake pedal being depressed further, the engine speed of the internal combustion engine1is impeded by the deceleration rate of the vehicle, and the engine speed falls at a faster rate. Therefore, in the internal combustion engine1, the engine speed decreases significantly before the timing of ignition in the cylinder in which the fuel combusts first, and there is a risk that the engine will stall without the fuel being able to combust and the internal combustion engine1cannot be started by a resuming of fuel injection. Therefore, the internal combustion engine1is started using the starter motor2instead of starting by resuming fuel injection when a restart request has been made during a brake ON state in which the brake pedal is depressed. The restart request during brake ON in which the brake pedal is depressed is not caused by an acceleration request from the driver. Therefore, there is little need to restart the internal combustion engine1early in response to a restart request during brake ON. Therefore, when a restart request has been made while the brake pedal is depressed, the internal combustion engine1is started using the starter motor2after the engine speed reaches “0,” rather than the internal combustion engine1being started by a resuming of fuel injection. Therefore, the lower limit (combustion recoverable rotational speed threshold R1) of the engine speed at which the engine can be started only by fuel injection does not need to be set by taking into account the increase in the deceleration rate of the internal combustion engine1that accompanies braking by the driver. That is, when a restart request has been made while the brake pedal is not being depressed, the region in which the engine is restarted only by fuel injection can be expanded. FIG.2is a timing chart showing how the automatically stopped internal combustion engine1is restarted, and shows a case in which the internal combustion engine1in a brake ON state is restarted. Time t1inFIG.2is a timing at which the automatic stop conditions of the internal combustion engine1are met. InFIG.2, the automatic stop conditions are met at time t1, at which the brake is ON and the vehicle speed is decreasing, and automatic stoppage of the internal combustion engine1is allowed. Time t2inFIG.2is a timing at which there is a request to restart the automatically stopped internal combustion engine1. That is, time t2inFIG.2is a timing at which any automatic restart condition such as those described above is met. In time t2inFIG.2, the engine speed is greater than the combustion recoverable rotational speed threshold R1, but the brake ON state is in effect. Therefore, the internal combustion engine1is not restarted by a starting of combustion, but is rather restarted by the starter motor2after the engine speed reaches “0.” Time t3inFIG.2is a timing at which the engine speed reaches “0” after the restart request. The starter motor2starts (switches to ON) at time t3. Time t3-t4ofFIG.2is a cranking period during which the crankshaft of the internal combustion engine1is caused to rotate by the starter motor2. FIG.3is a timing chart showing how the automatically stopped internal combustion engine1is restarted, and shows a case in which the brake becomes OFF and the vehicle reaccelerates when the automatically stopped internal combustion engine1is restarted. Time t1inFIG.3is a timing at which the automatic stop conditions of the internal combustion engine1are met. InFIG.3, the automatic stop conditions are met at time t1, at which the brake switches to ON and the vehicle speed is decreasing, and automatic stoppage of the internal combustion engine1is allowed. Time t2inFIG.3is a timing at which the acceleration pedal is depressed and a restart request is issued to the automatically stopped internal combustion engine1. That is, time t2inFIG.3is a timing at which any automatic restart condition such as those described above is met due to the brake pedal being depressed. In addition, time t2inFIG.3is a timing at which a foot of the driver leaves the brake pedal and a brake OFF state comes into effect. At time t2inFIG.3, a brake OFF state comes into effect and the engine speed will be than the combustion recoverable rotational speed threshold R1. Therefore, at time t2inFIG.3, a restarting of the internal combustion engine1due to a start of combustion is initiated. Time t3inFIG.3is a timing of the first combustion after fuel injection is resumed. When a restart request has been made in a state in which the clutch4is disengaged and the drive force of the internal combustion engine1is not being transmitted to the drive wheels7, if the engine speed of the internal combustion engine1is equal to or greater than the combustion recoverable rotational speed threshold R1(rotational speed threshold), the control unit21starts the internal combustion engine1by resuming fuel injection even in a brake ON state in which the brake pedal is depressed. When the clutch4is disengaged (clutch OFF), the internal combustion engine1will not be affected by any increase in the deceleration rate caused by braking by the driver. Therefore, when a restart request has been made, the control unit21starts the internal combustion engine1by resuming fuel injection if the engine speed of the internal combustion engine1is equal to or greater than the combustion recoverable rotational speed threshold R1while the clutch4is disengaged, even in a brake ON state. It is thereby possible to expand the region in which the internal combustion engine1is restarted only by fuel injection. FIG.4is a timing chart showing how the automatically stopped internal combustion engine1is restarted, and shows a case in which the clutch4is disengaged when the automatically stopped internal combustion engine1is restarted. Time t1inFIG.4is a timing at which the automatic stop conditions of the internal combustion engine1are met. InFIG.4, the automatic stop conditions are met at time t1, at which the brake switches to ON and the vehicle speed is decreasing, and automatic stoppage (coast stop) of the internal combustion engine1is allowed. At the timing of time t1inFIG.4, the clutch4is disengaged along with the initiation of the coast stop. Time t2inFIG.4is a timing at which a restart request is issued to the automatically stopped internal combustion engine1. That is, time t2inFIG.4is a timing at which any automatic restart condition such as those described above is met. At time t2inFIG.4, the brake ON state is in effect, but the clutch4is disengaged and the engine speed has exceeded the combustion recoverable rotational speed threshold R1. Therefore, at time t2inFIG.4, a restart of the internal combustion engine1via a combustion start is initiated. Time t3inFIG.4is a timing of the first combustion after fuel injection is resumed. Time t4inFIG.4is a timing at which the clutch4is engaged after the start of combustion in the internal combustion engine1. When a restart request has been made while the internal combustion engine1is stopped or when a restart request has been made while the speed of the vehicle is equal to or less than a predetermined low vehicle speed threshold V1at which little effect is caused by the deceleration rate of the internal combustion engine1regardless of the brake being ON, the control unit21starts the internal combustion engine1by resuming fuel injection even in a brake ON state. The internal combustion engine1is not affected by an increase in the deceleration rate caused by braking by the driver while the vehicle is stopped or the vehicle speed is equal to or less than the predetermined low vehicle speed threshold V1. Therefore, in either of these cases, the control unit21starts the internal combustion engine1by resuming fuel injection even if the brake is depressed. It is thereby possible to expand the region in which the internal combustion engine1is restarted only by fuel injection. FIG.5is a timing chart showing how the automatically stopped internal combustion engine1is restarted, and shows a case in which the vehicle speed is equal to or less than the low vehicle speed threshold V1when the automatically stopped internal combustion engine1is restarted. Time t1inFIG.5is a timing at which the automatic stop conditions of the internal combustion engine1are met. InFIG.5, the automatic stop conditions are met at time t1, at which the brake switches to ON and the vehicle speed is decreasing, and automatic stoppage of the internal combustion engine1is allowed. Time t2inFIG.5is a timing at which a restart request is issued to the automatically stopped internal combustion engine1. That is, time t2inFIG.5is a timing at which any automatic restart condition such as those described above is met. In time t2inFIG.5, the brake ON state is in effect, but the vehicle speed is a low speed equal to or less than the low vehicle speed threshold V1and the engine speed is greater than the combustion recoverable rotational speed threshold R1. Therefore, at time t2inFIG.5, a restart of the internal combustion engine1due to a combustion start is initiated. Time t3inFIG.5is a timing of the first combustion after fuel injection is initiated. FIG.6is a flowchart showing a flow of a control for the internal combustion engine1in the embodiment described above. In step S1, a determination is made as to whether or not a request to restart the internal combustion engine1has been generated. Specifically, a determination is made as to whether or not an automatic stop condition has been met during automatic stoppage of the internal combustion engine1. When it is determined in step S1that a restart request has been generated, the routine advances to step S2. When it is not determined in step S1that a restart request has been generated, the current routine is ended. In step S2, a determination is made as to whether or not the engine speed is equal to or greater than the combustion recoverable rotational speed threshold R1. If the engine speed is equal to or greater than the combustion recoverable rotational speed threshold R1in step S2, the routine advances to step S3. If the engine speed is not equal to or greater than the combustion recoverable rotational speed threshold R1in step S2, the routine advances to step S7. In step S3, a determination is made as to whether or not a brake OFF state is in effect. If a brake OFF state is in effect in step S3, the routine advances to step S4. If a brake OFF state is not in effect in step S3, the routine advances to step S5. In step S4, the internal combustion engine1is started by resuming fuel injection. In step S5, a determination is made as to whether or not a clutch OFF state is in effect. If a clutch OFF state is in effect in step S5, the routine advances to step S4. If a clutch OFF state is not in effect in step S5, the routine advances to step S6. In step S6, a determination is made as to whether or not the vehicle speed is equal to or less than the low vehicle speed threshold V1. If the vehicle speed is equal to or less than the low vehicle speed threshold V1in step S6, the routine advances to step S4. If the vehicle speed is not equal to or less than the low vehicle speed threshold V1in step S6, the routine advances to step S7. In step S7, the internal combustion engine1is started by cranking via the starter motor2. An embodiment of the present invention was described above, but the present invention is not limited to the embodiment described above; various changes can be made inasmuch as such changes do not deviate from the main point of the invention. For example, a rotational speed threshold is set according to the deceleration rate of the internal combustion engine, but it is also conceivable for the rotational speed threshold to not be set according to the deceleration rate of the internal combustion engine in a brake ON state. When a restart request has been made in a brake ON state while the engine speed of the internal combustion engine is decreasing due to automatic stoppage, either the rotational speed threshold need not be set or the rotational speed threshold may be set to infinity and the internal combustion engine may be caused to rotate using the electric motor and started. Furthermore, the rotational speed threshold may be set to a fixed value in a brake ON state. The embodiment described above relates to a method and device for controlling an internal combustion engine. | 23,508 |
11859589 | Like reference symbols in the various drawings indicate like elements. DETAILED DESCRIPTION A configuration of the DC power plant is discussed in detail below in relation to a thermal engine, in this case a Stirling engine. However, various other Stirling engines may be used. The system may be consolidated in a cabinet and interconnected for example via an isolated Controller Area Network (CAN) 2.0b or other electrical interface(s) that can facilitate communication and data processing between controllers and computers. In more complex systems further modules may be added to handle additional electrical resources. The system may include an LCD front display panel having multiple graphical user interfaces for system status monitoring and control inputs. Alternatively, a personal computer may be accommodated by USB, Ethernet, internet, wireless or other known communications format, to enable monitoring and control of the DC power plant. Referring now primarily toFIG.1, generator11and exemplary heat sink17A can be interconnected with modular power production system212. Exemplary heat sink17A can also include a power sink that can, for example, connect an electrical resistor that can dissipate excess electrical power from DC bus250(FIG.4E) by converting it to heat. In some configurations, the power from DC bus250(FIG.4E) may be purposely directed to brake module19A (FIG.4H) to create heat as the primary purpose of the system. A generator module can include a power source that can convert the polyphase electrical power from engine11into DC power primarily for residential load28A. In some configurations, Stirling engine11A (FIG.3), as described in U.S. patent application Ser. No. 12/829,320 filed Jul. 1, 2010, now U.S. Publication No. US-2011-0011078-A1 published Jan. 20, 2011 and entitled Stirling Cycle Machine (Attorney Docket No. 178), which is hereby incorporated herein by reference in its entirety, may generate power in some configurations. Referring now primarily toFIG.2, modular power production system212can consolidate power control39(FIG.3), including hardware and software, in an interchangeable modular or “block” format. It is the goal of this format to be able to generate and provide DC power from, for example, but not limited to, Stirling engine11A (FIG.3), wind, thermal, and photovoltaic to load28(FIG.3). Power production214can include, but is not limited to including, in some configurations, electricity production and communication between “electric resources” and for example, but not limited to, electricity production from low level producer(s) such as, for example, but not limited to, Stirling engine11A (FIG.3), wind turbine, or photovoltaic array. Electricity can be provided to load28(FIG.3) such as, for example, but not limited to, a commercial or residential building, directly. An electric resource can be an electrical entity that can act as load28(FIG.3), generator11(FIG.1), or storage. In modular power production system212, each module or “block” is interchangeable to facilitate power production214and power consumption220. The term digital signal processor (DSP) may be used herein to describe any micro-processor with sufficient input/output and speed to read voltages, currents, control multiple sets of half-bridge circuits. In some configurations, the DSP microprocessor can run at 150 MHz. System controller53(FIG.3) for modular power production system212may include a data input/output device such as a keyboard and display or a touch-sensitive display or communication port to allow users to control the operation of modular power production system212. Modular power production system212may also include a wireless or hard wired telecommunication ability to allow remote control and access to the system data. An alternative configuration may place all the computing power in a master controller. Thus the operation of each module could be fully under the control of one or more DSPs in the master controller. Referring now primarily toFIG.3, Stirling engine11A, which can be controlled by system controller53A through engine controller49, can produce a mechanical output that can drive, for example, but not limited to, permanent magnet synchronous motor (PMSM)13. Other motors are possible such as, for example, but not limited to, an induction motor and a synchronous reluctance motor. PMSM13can be controlled or conditioned to effectively run as an AC motor/generator providing consistent three-phase power to load28despite the variable torque generated by Stirling engine11A. Charging a battery system (not shown) can overcome variable torque. The battery system can receive incoming power, no matter any torque or power fluctuations from the input and/or motor, and can store the power for application to load28. In some configurations, PMSM13can be controlled with power controller39including, for example, but not limited to, motor power board15and brake chopper19A (FIG.4H). Power controller39may also receive data and information from system controller53A. Continuing to refer primarily toFIG.3, in some configurations, engine power output can be matched to the DC power demand from externally connected and variable loads28. Efficiency can be improved if engine11(FIG.4G), for example Stirling engine11A, does not produce power that is in excess of what is demanded. If excess power is produced, the power can be dissipated through, for example, but not limited to, shunt load17(FIG.4H) and brake chopper19A (FIG.4H). The engine power output can be kept slightly higher than load28so that there is a buffer of available power for instantaneous supply that can cover a pre-selected increase in demand. Power control board39can continuously communicate to motor power board15indicating the present state of the power excess. Power excess can be calculated by observing the amount of power being dissipated in the combination of, for example, but not limited to, shunt load17(FIG.4H) and brake chopper19A (FIG.4H). Power control board39can control igniters29(FIG.4G). In some configurations, igniters29(FIG.4G) can require a power supply of approximately 120V DC at approximately 8 amps. Power control board39can include a voltage controller and a current controller that can use conventional proportional-integral (PI) controllers with voltage and current feedback circuits. Power control board39can also include logic that can include pre-selected voltage and current regulation values. The voltage regulation value can act as reference input to the voltage controller which can provide a current regulation reference to the current controller, while the current regulation value can act as a limit to the current reference value produced by the voltage controller. A third PI controller can reduce the power being supplied to the igniters29(FIG.4G) by monitoring the system DC voltage level to ensure that igniters29(FIG.4G) do not rob the system of power when it may be needed for other purposes. Note that system100(FIG.4G) can produce DC power for igniters29(FIG.4G) as well as motor power board15, DC output board19, and pump, fan, and blower drive34(FIG.4I). The third PI controller can reduce the current regulation limit value that acts upon the current controller. By restricting the amount of current that can flow through igniters29(FIG.4G), the power consumed by igniters29(FIG.4G) can be reduced in proportion. In some configurations, the current limit control can be reduced to zero. Referring now primarily toFIGS.4A-4F, in some configurations, major components of second DC power plant configuration can include, but are not limited to including, start-up power components103A (FIG.4F), power controller105A (FIG.4E), Stirling engine11A (FIG.4D), sensors109A (FIGS.4A/4C), and system controller107A (FIG.4A). In operation, power from start-up power components103A (FIG.4F) can be sent to motor13(FIG.4F) which can supply torque to start Stirling engine11A (FIG.4D). Start-up power components103A (FIG.4F) can also send power to system controller107A (FIG.4A) and power controller105A (FIG.4E). Burner301(FIG.4B), fueled by, for example, but not limited to, propane or natural gas, can ignite and heat a working gas that can maintain motion in Stirling engine11A (FIG.4D). After Stirling engine11A (FIG.4D) comes up to speed, it can send energy back to motor13(FIG.4B) which can act as a generator sending power to system controller107A (FIG.4A), power controller105A (FIG.4E), and to DC load28(FIG.4E). Start-up power components103A (FIG.4F) can be taken out of the circuit by diode38(FIG.4F) so that power from motor/generator13(FIG.4B) can flow to the other parts of system300without flowing back to start-up power components103A (FIG.4F). When motor/generator13(FIG.4B) is generating power, power from start-up power components103A (FIG.4F) for system controller107A (FIG.4A) and power controller105A (FIG.4E) can become unnecessary. Continuing to refer primarily toFIGS.4A-4F, in some configurations, Stirling engine11A (FIG.4D) can contain a working fluid and burner301(FIG.4B) for heating the working fluid of Stirling engine11A (FIG.4D), an airlock space separating the crankcase and the working space for maintaining a pressure differential between the crankcase housing and the working space housing and airlock pressure regulator303(FIG.4D) connected between the crankcase and one of the airlock space and working space. System controller107A (FIG.4A) can process a number of failsafe triggers based on sensor data from sensors109A (FIGS.4A/4C) and controller evaluation algorithms that can evaluate system300and determine if system300should be turned to shut-down or stop mode. Levels of heat, power, and oxygen, for example, can be monitored and shut-down or engine stoppage can be performed, or other modifications to system300and Stirling engine11A (FIG.4D), if a temperature reading is too high, or if exhaust oxygen level is too high, or if engine speed exceeds a desired value, or if the differential pressure within the air lock is too low, for example. These are exemplary triggers for starting shut-down or stop procedures, other triggers could be used as well or in combination with these examples. Continuing to refer primarily toFIGS.4A-4F, system300can include blower305(FIG.4E) that can provide air or other gas for facilitating ignition and combustion in burner301(FIG.4B). System300can also include a preheater (details not shown) that can, for example, but not limited to, define an incoming air passage and an exhaust passage separated by an exhaust manifold wall that can, for example, but not limited to, heat incoming air from the hot exhaust expelled from the heating element, a fuel injector (details not shown) that can, for example, but not limited to, supply fuel to mix with the incoming air, igniter29(FIG.4B) that can, for example, but not limited to, ignite the fuel/air mixture, a prechamber (details not shown) that can, for example, but not limited to, define an inlet for receiving the fuel/air mixture and promote ignition of the mixture, a combustion chamber (details not shown) that can, for example, but not limited to, be disposed linearly below the prechamber that can, for example, but not limited to, maintain supporting a flame developed and ignited in the prechamber, and an electronic control unit (details not shown) that can, for example, but not limited to, control ignition and combustion operations of burner301(FIG.4B), and wherein the combustion chamber can be connected to the exhaust passage into which the exhausted combustion gases are pushed to heat the incoming air following combustion and heating of the engine or machine. During normal engine operation, blower305(FIG.4E) can be operated at least partially by a control loop which can measure the excess oxygen in the exhaust to determine blower speed. Failsafe triggers can include when engine speed exceeds a predetermined range, oxygen levels in exhaust exceed a predetermined range, generator temperature exceeds a predetermined range, burner temperature exceeds a predetermined range, cooler temperature exceeds a predetermined range, flame/ignition failure, and/or repeatable failure of flame ignition, for example. The described control method is not limited to the disclosed triggers and other triggers, factors, and variables may also be analyzed by system controller107A (FIG.4A) under the start-up and operation modes. Continuing to still further refer primarily toFIGS.4A-4F, system controller107A (FIG.4A) may be separate from but connected to and in communication with power controller105A (FIG.4E) and a hardware scheme that facilitates conversion of mechanical to electrical energy essentially downstream from Stirling engine11A (FIG.4D). Some configurations of the power electronics may be those described in '897. System controller107A (FIG.4A) can provide Stirling engine11A (FIG.4D) operational control including, but not limited to, regulation of an airlock such as, for example, but not limited to, the airlock described herein as well as for example burner(s)301(FIG.4B). Blower305(FIG.4E) can provide the air flow for combustion in burner(s)301(FIG.4B), as well as cooling of a burner enclosure. System controller107A (FIG.4A) can control the air flow via a speed command passed to variable frequency drive (VFD)35(FIG.4I). A blower speed signal may provide a feedback signal to system controller107A (FIG.4A) which can permit, for example, but not limited to, evaluation and control of the blower drive by the system controller107A (FIG.4A). Still further referring primarily toFIGS.4A-4G, in some configurations, for each burner301(FIG.4B), flame detection module47(FIG.4B) can be provided for safety, temperature control, and the ignition process among other things. In some configurations, igniter(s)29(FIG.4B) for each burner301(FIG.4B) can be directly influenced by flame sensors307(FIG.4B) through system controller107A (FIG.4A), and igniter(s)29(FIG.4B) can be controlled via igniter signal lines309(FIG.4B) based on the flame sensor data and other data from the engine such as oxygen sensors, for example. In various configurations, coolant flow and temperature can be inputs to system controller107A (FIG.4A) to control coolant flow pump311(FIG.4E) and ensure that appropriate coolant temperature is maintained in Stirling engine11A (FIG.4D). In some configurations, airlock delta pressure regulator (AdPR)343(FIG.4D) can be directly connected and controlled via system controller107A (FIG.4A). In some configurations, system controller107A (FIG.4A) may also communicate with power controller105A (FIG.4E) over CAN bus313(FIG.4A) but could also, in some configurations, rely on wireless communications or other communications protocols such as USB. System controller107A (FIG.4A) may, in some configurations, command the speed of motor/generator13(FIG.4F). Configurations of power electronics as they relate to control and monitoring of motor/generator13(FIG.4F) may be those described in '897. In some configurations, system controller107A (FIG.4A) and power controller105A (FIG.4E) may exchange data and commands including, but not limited to, motor drive velocity command, generator velocity, bus voltage, bus current, motor drive IGBT bridge temperature, shunt control, shunt active, battery voltage, battery temperature, inverter power, inverter enable, inverter PWM, inverter voltage inverter current, inverter temperature, converter power, converter enable, converter PWM, converter voltage, converter current, and converter temperature. In some configurations, the term converter refers to one or more DC/DC converter circuits. Certain direct inputs into system controller107A (FIG.4A) may also be necessary and can include but are not limited to including, oil temperature from the crankcase, battery temperature, motor temperature, and shunt temperature. Referring now primarily toFIGS.4G-4J, components of system300(FIGS.4A-4F) important to the improvements of some configurations are shown in system100for producing DC power for load28(FIG.4H). System100can include, but is not limited to including, engine11(FIG.4G) initially powered by relatively small power supply41(FIG.4J) supplemented by capacitor bank37(FIG.4G). System100can further include PMSM13(FIG.4G) operably coupled to engine11(FIG.4G). PMSM13(FIG.4G) can convert electrical energy to mechanical energy (torque) to provide required startup for engine11(FIG.4G). PMSM13(FIG.4G) can act as a generator powered by engine11(FIG.4G) after engine11(FIG.4CGis up to speed, and can provide AC current to motor power board15(FIG.4G). Motor power board15(FIG.4G) can convert the AC current to DC power. System100can also include DC output board19(FIG.4H) operably coupled to motor power board15(FIG.4G). DC output board19(FIG.4H) can disable output of the DC power from motor power board15(FIG.4G) during a first set of pre-selected conditions. System100can include di/dt limiter21(FIG.4H) operably coupled to DC output board19(FIG.4H). di/dt limiter21(FIG.4H) can limit a rate of change of current flow from DC output board19(FIG.4H) during a second set of pre-selected conditions. di/dt limiter21(FIG.4H) can be a cost-effective way to control current flow from DC output board19(FIG.4H). In some configurations, di/dt21(FIG.4H) can include, for example, a toroidal core constructed and available from, for example, but not limited to, micrometals.com as powdered iron alloy #2. Core material #2is characterized by the property that it does not saturate. System100can further include EMI filter23(FIG.4H) operably coupled to di/dt limiter21(FIG.4H). EMI filter23(FIG.4H) can reduce conducted and radiated emissions of the DC power from di/dt limiter21(FIG.4H). System100can still further include ARC fault detector25(FIG.4H) operably coupled to EMI filter23(FIG.4H) and DC output breaker27(FIG.4H). ARC fault detector25(FIG.4H) can shunt trip DC output breaker27(FIG.4H) during a series ARC fault condition. DC output breaker27(FIG.4H) can provide the DC power to load28(FIG.4H) when a third set of pre-selected conditions is false. The first set of pre-selected conditions can optionally include overcurrent and ground fault conditions, the second set of pre-selected conditions can optionally include abnormal conditions, and the third set of pre-selected conditions can optionally include an abnormal overcurrent condition. Continuing to refer primarily toFIGS.4G-4J, resolver59(FIG.4G) is a position measurement device used for commutation of PMSM13(FIG.4G). The fuel source for engine11(FIG.4G) can be, for example, but not limited to, propane gas or natural gas. PMSM13(FIG.4G) can be used as a motor initially to start engine11(FIG.4G). Once engine11(FIG.4G) is turning and producing power, PMSM13(FIG.4G) can be used as a generator to control the velocity of engine11(FIG.4G) and extract power from engine11(FIG.4G). PMSM13(FIG.4G) can be brought up to an approximate alternator electrical speed before it locks (synchronizes) to a selected rotational rate. Once up to speed, PMSM13(FIG.4G) can maintain synchronism with the AC power source, can develop torque, and can maintain a constant speed. When PMSM13(FIG.4C) is 3-phase 4-pole, for example, it can generate an electrically rotating field in the stator. The three phases of stator excitation can add vectorially to produce a single resultant magnetic field which can rotate at 1800 rpm with 60 Hz power or 1500 rpm with 50 Hz power. System100can include motor power board15(FIG.4G), including a 3-phase, 4-quadrant AC/DC converter used for velocity control of PMSM13(FIG.4G). System100can further include DC output board19(FIG.4H) including brake chopper19A (FIG.4H), output enable and protection19B (FIG.4H), and shunt trip control19C (FIG.4H). DC output board19(FIG.4H) can be operably connected to power control board39(FIG.4H) and resolver59(FIG.4G). Brake chopper19A (FIG.4H) can limit DC bus voltage by, for example, but not limited to, switching the excess energy to shunt load17(FIG.4H). Output enable and protection19B (FIG.4H) can disable output power from the DC output terminals during overcurrent or ground fault conditions. Shunt trip control19C (FIG.4H) can control the fault conditions under which shunt trip61(FIG.4H) is driven. The fault conditions can include, but are not limited to including, arc fault, ground fault, and unexpected loss of control power. Continuing to refer primarily toFIGS.4G-4J, system100can further include di/dt limiter21(FIG.4H), EMI filter23(FIG.4H), arc fault detector25(FIG.4H), and DC output breaker27(FIG.4H). di/dt limiter21(FIG.4H), operably electrically coupled with DC output board19(FIG.4H) and EMI filter23(FIG.4H), can provide series inductance to limit current rate of change under abnormal conditions. Commercially available EMI filter23(FIG.4H) (for example, but not limited to,50A), operably electrically coupled with di/dt limiter21(FIG.4H) and arc fault detector25(FIG.4H), can reduce conducted and radiated emissions. Commercially available arc fault detector25(FIG.4H), operably electrically coupled with EMI filter23(FIG.4H) and DC output breaker27(FIG.4H), can shunt trip DC output breaker27(FIG.4H) during a series arc fault condition. Commercially available DC output breaker27(FIG.4H) (for example, but not limited to,50A), operably electrically coupled with arc fault detector25(FIG.4H) and the external load, can disconnect the DC power plant + and − terminals from external load28(FIG.4H) in the event of an abnormal overcurrent condition. Arc fault detector25(FIG.4H) can be operably connected to shunt trip61(FIG.4H) and shunt trip control19C (FIG.4H). DC output breaker27(FIG.4H) can be operably connected to shunt trip61(FIG.4H). Continuing to refer primarily toFIGS.4G-4J, system100can also include igniters29(FIG.4G), hot surface ignition sources, that establish flame in burner301(FIG.4B). System100can also include igniter power board31(FIG.4G) (for example, but not limited to, 400 VDC to 120 VDC, 600 W), a DC/DC buck converter used to drive hot surface igniters29(FIG.4G), with which igniter power board31(FIG.4G) can be operably electrically connected. Igniters29(FIG.4G) and igniter power board31(FIG.4G) can be powered by startup DC bus power41(FIG.4J) during startup, and by PMSM13(FIG.4G) while system100is in run mode. Igniter power board31(FIG.4G) can be operably connected to power control board39(FIG.4H). System100can also include pump, fan, and blower drive34(FIG.4I) including induction motor33(FIG.4I) and variable frequency drive35(FIG.4I) (VFD) used to drive induction motor33(FIG.4I) to cool engine11(FIG.4G). VFD35(FIG.4I) can be operably connected to engine control I/O PCB49(FIG.4I). Pump, fan, and blower drive34(FIG.4I) can include combustion air blower305(FIG.4E) providing combustion air to burner301(FIG.4B). A combustion air pressure switch to prevent fuel flow if combustion air blower305(FIG.4E) flow is low can also be included. Coolant pump311(FIG.4E) can also be included that provides coolant flow to engine11(FIG.4G) used to maintain proper engine temperatures. Fuel control modulating valve315(FIG.4A) can modulate a gas valve that controls fuel flow into burner301(FIG.4B) to regulate heat transfer surface temperature of engine11(FIG.4G). Fuel regulator317(FIG.4A) can regulate fuel pressure into burner301(FIG.4B). Radiator fan319(FIG.4E) can provide system cooling to maintain temperature differential that drives engine11(FIG.4G). Pressure vessel overpressure relief device321(FIG.4D) can limit the pressure in a pressure vessel under abnormal conditions. The pressure vessel can contain helium working gas for engine11(FIG.4G). Power burner301(FIG.4B) can provide heat to the heat transfer surface of engine11(FIG.4G) to create heat differential that can drive, if engine11(FIG.4G) is Stirling engine11A (FIG.4D), the Stirling cycle. Heater head high-limit thermocouple325(FIG.4C) is a hardware safety overtemp that can provide equipment protection. A helium fill system can be used to maintain proper helium pressure in the Stirling engine pressure vessel. The fill system can include helium bottle323(FIG.4D), pressure transducer, gas pressure regulator329(FIG.4D), and solenoid valve327(FIG.4D). Main gas valve331(FIG.4B) can be a dual solenoid valve that isolates system100from a main gas supply. Fuel valve interlock contacts333(FIG.4A) or optional contacts can be included that can be wired to a remote on/off switch, a CO detector, and/or a heat alarm. An airlock can separate a wet lubricated sump from a dry workspace. The airlock can include a differential pressure transducer and an electric pump motor for closed loop control of airlock pressure. Continuing to refer primarily toFIGS.4G-4J, system100can optionally include diode38(FIG.4G) inhibiting current flow from motor power board15(FIG.4G) to capacitor bank37(FIG.4G) as discussed herein. PMSM13(FIG.4G), along with motor power board15(FIG.4G) and engine control board49(FIG.4I), can control engine11(FIG.4G). PMSM13(FIG.4G) can optionally be a 3-phase generator. Motor power board15(FIG.4G) can provide 12 kVA, and be a 3-phase, 4 quadrant AC/DC converter. In some configurations, EMI filter23(FIG.4H) can include a50A filter, DC output breaker27(FIG.4H) can include a50A breaker, DC power can be delivered at 390 VDC, relatively small power supply41(FIG.4J) can supply 380 VDC @4A, and the capacity of capacitor bank37(FIG.4G) can be a function of the starting torque. In some configurations, more or less power can be supplied, where each other power component can be scaled according to the overall system requirements. System100can include system control power source45(FIG.4I) and start-up system control power source43(FIG.4J). Power control board39(FIG.4H) and system control board53(FIG.4J) can optionally include commercially available hardware and software to implement controller area network (CAN) bus313(FIG.4J). Exemplary messages exchanged over CAN bus313(FIG.4J) are described herein. System100can further include engine control input/output (I/O) board49(FIG.4I) operably connected to start-up control power43(FIG.4J), external on/off control58(FIG.4I), and system control power45(FIG.4I). Engine control board49(FIG.4I) can be powered at start-up by start-up control power43(FIG.4H), and then during operation by engine11(FIG.4G) through system control power45(FIG.4I). Continuing to refer primarily toFIGS.4G-4J, system100can include at least one start-up DC bus power41(FIG.4J), an AC mains-derived DC power supply used during engine starts. Start-up DC bus power41(FIG.4J) can supply power to DC bus250(FIG.4E) and ultimately engine11(FIG.4G), and can derive its power from AC power source63(FIG.4J). In some configurations, start-up DC bus power41(FIG.4J) can supply, for example, but not limited to, 380 VDC @4A. When that is not enough power to start engine11(FIG.4G), at least one motor start capacitor bank37(FIG.4G) can supply some of its stored energy to start engine11(FIG.4G). Motor start capacitor bank37(FIG.4G) can be sized at, for example, but not limited to, 24.6 milli-Farads. The pairing of start-up DC bus power41(FIG.4H) with motor start capacity bank37(FIG.4G) can allow start-up DC bus power supply41(FIG.4H) to be relatively smaller than a power supply that would alone supply peak power required for start-up of engine11(FIG.4G). DC bus power41(FIG.4H) can optionally be enabled which can be powered, at start-up, by start-up control power43(FIG.4H), an AC mains-derived DC power supply used during engine starts that can supply power (for example, but not limited to, 23 VDC @5A) to engine control I/O board49(FIG.4I), system control board53(FIG.4J), and power control board39(FIG.4H). After engine start-up and current flow begins, diode38(FIG.4G) can prevent current from flowing into motor start capacitor bank37(FIG.4G) and start-up DC bus power41(FIG.4J). Further, when engine11(FIG.4G) is operational, it can supply current to power subsystem105A (FIG.4I), which can replace start-up control power43(FIG.4J) as the power supply for control subsystem107A (FIG.4A) by providing a higher voltage, for example, but not limited to 24 VDC @5A, relative to the power of start-up control43(FIG.4J) which can be, but is not limited to being, 23 VDC @5A. Referring still primarily toFIGS.4G-4J, system control power45(FIG.4I) can be the power supply on DC bus250(FIG.4E) that can supply power to system and power controllers at 24 VDC @12A. Some configurations of power control board39(FIG.4H) are described in part in United States Patent Application #s 2013-0099565, 2014-0091622, WO 2014/152706, and 2015-0084563, all entitled Modular Power Conversion System. In some configurations, Modular Power Conversion System, upon which power control board39(FIG.4H) can be based, can convert any form of electrical power to any other form of electrical power and optimize the available sources and loads based on real time pricing and demand variables without grid feedback. Power control board39(FIG.4H) can be an embedded control and acquisition system that can include a digital signal processor, I/O and peripherals. Power control board39(FIG.4H) can send control signals to motor power board15(FIG.4G), DC output board19(FIG.4H), and igniter power board31(FIG.4G). The control signals can include, but are not limited to including, conventional low voltage differential signaling (LVDS) gate control signals. Other control signals can include LVDS Bridge Fault and Status Signals and inter-integrated circuit communication signals. Power control board39(FIG.4H) can monitor 240 VAC63through monitor line3130(FIGS.4H/4J). System100phase locks to 240 VAC input63(FIG.4J) to measure voltage and frequency and report these via CANbus313(FIG.4J) to system control board53(FIG.4J). System control board53(FIG.4J) can, for example, but not limited to, decide whether to allow an engine start sequence depending on whether 240 VAC63(FIG.4J) appears to be within acceptable tolerances. System control board53(FIG.4J) can also record the reported voltage and frequency in a continuously running log file. The recorded frequency measurement may indicate when an externally attached grid-forming inverter is using a frequency shift method of signaling a change in power demand to other attached grid tied inverters. Referring again primarily toFIGS.4G-4J, system100can further include engine control I/O board49(FIG.4I), including VFD control49A (FIG.4I), hardware safety interlock49B (FIG.4I), I/O and sensor interface49C (FIG.4I), and system control interface49D (FIG.4I). System100can also include system control board53(FIG.4J) that can enable, for example, but not limited to, embedded control and acquisition. Engine control I/O board49(FIG.4I) can be powered by startup DC bus power41(FIG.4J) until engine11(FIG.4G) is running. Engine control I/O board49(FIG.4I) can be operably connected to system control board53(FIG.4J), and emergency power off (EPO) switch57(FIG.4I). System control board53(FIG.4J) can be operably connected to external computer controller55(FIG.4J) (and ultimately network20(FIG.4J)). External on/off control58(FIG.4I) can include, but is not limited to including, a contact closure that can be used to signal system100to start. Engine control I/O board49(FIG.4I) can include, but is not limited to including, commercially available components such as, for example, National Instruments (NI) cRIO 9023, NI 9112 FPGA 8 slot chassis, NI 9213 Thermocouple module, NI 9426 Digital Input Module, NI 9477 Digital Output Module, ONI 9205 Analog Input Module, NI 9264 Analog Output Module, NI 9505 DC Servo Drive Module, NI 9375 Digital IO Module, and NI 9853 CAN Communications Module. Continuing to refer primarily toFIGS.4G-4J, system100can further include, but is not limited to including, system I/O and sensors51(FIG.4I) and flame detect module47(FIG.4I). Flame detect module47(FIG.4I) can, for example, but not limited to, monitor the presence of flame in burner301(FIG.4B); the monitoring can avoid accumulation of unburnt fuel in a burner system. Parameters that can be sensed by system I/O and sensors51(FIG.4I) can include, but are not limited to including, (1) motor stator inner thermistor344(FIG.4C) that can monitor stator temperature of PMSM13(FIG.4G) for equipment protection, (2) airlock pressure sensor347(FIG.4D) that can maintain proper helium pressure in engine11(FIG.4G), (3) coolant flow sensor337(FIG.4F) that can monitor coolant flow in system100where the monitoring can protect engine11(FIG.4G), (4) coolant pressure relief valve341(FIG.4F) that can limit the pressure in the cooling system under abnormal conditions, (5) cooler thermistor343(FIG.4C) that can monitor coolant temperature in engine11(FIG.4G) for equipment protection and control, (6) a crankcase pressure sensor (not shown) that can monitor bulk working gas pressure in a pressure vessel of engine11(FIG.4G), (7) exhaust gas oxygen sensor349(FIG.4D) that can monitor the oxygen level in burner exhaust gas and for closed loop control of a fuel/air ratio, (8) flame temperature thermocouple sensor351(FIG.4C) that can monitor the temperature of a power burner flame, (9) swirler thermocouple353(FIG.4C) that can monitor air preheat temperature in a burner recuperator, (10) heater head thermocouple355(FIG.4C) that can monitor the temperature of a heat transfer surface of engine11(FIG.4G), (11) oil pressure sensor357(FIG.4D) that can monitor oil pressure in engine11(FIG.4G) for equipment protection, and (12) oil temperature thermistor361(FIG.4D) that can monitor oil temperature in engine11(FIG.4G), where the monitoring can protect the equipment. Referring now primarily toFIGS.5A-5C, phase lock loop (PLL)500(FIG.5A) can integrate frequency-based grid connection safety features into system100(FIGS.4C-4F). PLL500(FIG.5A) can include sawtooth waveform generator509(FIG.5B) that can provide angle θ507(FIG.5B) to polynomial calculation561A which can produce sine and cosine pair (quadrature)509(FIG.5B) for angle θ507(FIG.5B). Angle θ507(FIG.5B) can be constantly swept from 0° through 360° (via sawtooth505(FIG.5B)) at rate (i.e. frequency) which can be varied, for example, but not limited to, under software control to achieve an operating frequency of 60 Hz +/− approximately 6 Hz. To achieve phase lock with the grid, a phase error signal can be derived by multiplying sine563(FIG.5A) of the phase lock loop reference by the grid voltage Vab which is assumed to be a sinusoidal signal also operating at approximately 60 Hz. At this step, the voltage Vab is taken to be cosine565(FIG.5A) of the grid voltage. By multiplying sine563(FIG.5A) of the reference by cosine565(FIG.5A) of the grid, a signal567(FIG.5A) is produced which contains both an AC and a DC component. The AC component will vary in amplitude according to the amplitudes of the reference and the grid, and will have a frequency of 2× the grid frequency once the loop is locked. The DC component will vary in amplitude according to the phase error between the reference and the grid. Since the reference and the grid form a quadrature pair, the phase error will be zero when they are 90° apart. With a known phase error557(FIG.5B), PI controller503(FIG.5B) can be applied to create a closed loop control which can drive phase error557(FIG.5B) to zero by modulating frequency. In some configurations, system100(FIGS.4C-4F) can operate within the constraints of fixed-point integer math and a fixed frequency (10 kHz) carrier rate. The 10 kHz carrier rate means that angle θ507(FIG.5B) is updated once every 100 μsec. Angle θ507(FIG.5B) is represented by an unsigned 16-bit value where zero=0° and 216−=359.995°. Continuing to refer toFIGS.5A-5C, to achieve a frequency of 60 Hz, angle θ507(FIG.5B) must sweep from 0° through 360° in 16.6 ( 1/60) msec with a constant increment applied once every 100 μsec (the carrier period). This increment can be calculated as follows: (65536/10000 Hz)×60 Hz=393.216 where 65536=360° as represented by the angle θ, 10000 Hz=carrier frequency, and 60 Hz=desired angle θ→frequency. Fixed point integer math cannot produce a non-integral increment on an individual carrier. The nearest two integral values (in this case 393 and 394) are interleaved so that the average increment equals the exact required increment over some number of carriers, referred to herein as fractional clock division. Fractional clock divider551(FIG.5C) can follow PI controller503(FIG.5B), and can utilize a combination of 32-bit center frequency input553(FIG.5C) (e.g. 60 Hz) and a 16-bit delta frequency input555(FIG.5C) which can be driven by PI controller503(FIG.5B). 32-bit center frequency value553(FIG.5C) can allow direct representation of the fractional increment value where the delta frequency input allows PI controller503(FIG.5B) to operate in its natural bipolar mode centered on zero. Even operating at a fixed frequency (holding delta frequency at a constant) the output of clock divider551(FIG.5C) will not be a constant, but, in the case of a 60 Hz system, the output of clock divider551(FIG.5C) will be toggling between 393 and 394 in a predictable pattern. Thus, the instantaneous value of output from clock divider551(FIG.5C) may not be able to be used as a direct indication of operating frequency because the value is constantly changing. Frequency measurement accuracy and/or PLL stability can be affected by the AC component (sinusoidal) in phase error signal557(FIG.5B). Feeding phase error557(FIG.5B) into PI controller503(FIG.5B) can cause the error to propagate directly through PI controller503(FIG.5B) which could cause the instantaneous value of the frequency to be incorrect. Using low pass filter501A (FIG.5A) to filter phase error557A (FIG.5A) before supplying it to PI controller503(FIG.5B) could eliminate most of the AC component which is not relevant to the control. Referring now primarily toFIGS.5D-5I, in an exemplary use of the logic fromFIGS.5A-5C, dual PLLs can be used in system100(FIGS.4C-4F) to monitor grid voltage and frequency. Specifically, first digital phase locked loop (DPLL)500A (FIG.5E) can track grid voltage and frequency when the voltage and frequency are within tolerance. Second DPLL500B (FIG.5H) can continuously measure and report grid frequency561(FIG.5H) and phase error559(FIG.5H), and can remain locked over as wide a range as possible. Grid voltage measurement can be referenced to second DPLL500B (FIG.5H). Conditions that can be required for PLL lock are that (1) absolute error must be less than a threshold, and (2) input voltage must be within a threshold. Low pass filter501B (FIG.5E) can be used to filter the output of first DPLL500A (FIG.5E) to improve PLL performance. Referring now primarily toFIG.6, velocity control for PMSM13can include power electronic circuit722for 3-phase PMSM13. Other control loop structures may also be used to control PMSM motor/generator13or other motors as well. Analog/digital (A/D) converter752can convert analog sensor signals from PMSM motor13to digital signals for use by digital signal processor (DSP)754. Digital Hall sensors (not shown) can be used to eliminate A/D converter752. Voltage sensors262and current sensors260can be provided for 3-phase demodulation of the three phase signals ABC and, applying Clarke/Park transforms, given sin/cos of the electrical angle, the 3-phase signal can be converted to a 2-phase orthogonal (xy) reference frame, and then from the stationary reference frame to the rotor (dq) reference frame for vector current loop764. Each of the Clarke/Park orthogonal reference frame transform760and rotor reference frame transform762have different scaling and normalization factors and circuitry can be provided to prevent saturation of the output duty cycle and allow significant amplitude to be added to the net output duty cycle. Position/velocity estimator766can receive signals from motor velocity sensor753sensing the velocity of PMSM motor13, as well as orthogonal reference frame transform760, and can compile a position and velocity estimation of PMSM motor13. Vector current loop764, orthogonal reference frame transform760, rotor reference frame transform762, PWM registers756, 3-phase bridge758, and position velocity estimator766can execute in a motor velocity control loop768which can receive commands from system control board53via power control board39to directly control PMSM motor/generator13. Continuing to refer primarily toFIG.6, Stirling engine11A (FIG.3) does not produce constant output torque, so as it operates, the torque oscillates up and down. To control the motor torque of PMSM motor/generator13and hence the velocity, vector current feedback loop764can be used so that the variable torque from Stirling engine11A (FIG.3) and the resultant DC power do not detrimentally effect PMSM motor/generator13. Vector control of PMSM motor/generator13can be used with a velocity control state machine using essentially three different control states: start-up, starting and running states. Position/velocity estimator766can estimate position/velocity through information provided by position sensors, for example resolver59(FIG.3), or three Hall sensors (not shown) at, for example, 60°. DC bus sensor753A can provide DC bus status information to A/D converter752. Referring now primarily toFIG.7, using Hall sensors in their stateless form it is possible to decode the sector from the Hall sensor and compute position increment and unwrap, which can provide a raw Hall angle and an indication of which positional motor segment the rotor is in. In order to obtain the necessary motor speed estimate for motor power board15(FIG.3), the position can be differentiated, or a feedback loop can be used. Method9150can include estimating9100rotor speed and integrating9101estimated speed to get an estimated rotor position. Method9150can further include receiving9102a Hall sensor digital signal and obtaining9103from the digital signal a raw estimate of angle of the rotor with each 60° step of the motor cycle, and unwrapping9104the raw estimate bit by extending the lowest significant bits of the sensor information over time to obtain a bit extended input position. Method9150can include transforming9105a sawtooth error from the Hall sensor by putting the input position through a deadband block. The deadband range can compensate for the +30° and −30° limit of known natural error of a Hall sensor. The deadband range is 70-80% of this limit of natural error and therefore everything outside the error which exists within the deadband range may be essentially disregarded and/or moved towards a zero value. Error may also be limited by the use of techniques and methods for dynamically setting limits on the commanded current. Method9150can further include comparing9106the estimated rotor position to the measured rotor position from the Hall sensor(s) to produce an error term. Method9150can include computing9107a position error based on the error term, and changing9111the initial speed estimate based on the position error. Method9150can optionally include if9108the error is greater than an error threshold, clipping9110the difference between the estimated position and the measured position. Method9150can further optionally include if9108the error is less than or equal to the error threshold, if9109the error is less than or equal to the error threshold, using the estimated rotor speed. Current limits can be used in electronic circuitry in order to prevent excessive current that may result in catastrophic failure of electronic components, in this case motor/generator13(FIG.3). In some configurations, the generation of commands for current which can prevent the current from exceeding a dynamically predetermined limit can be used. The limit may be determined for example as a function of power dissipation in a component as estimated from a measured current level and as a function of a measured temperature proximate to the component. Other methods and techniques for limiting current are possible as well. Some of these are described in U.S. Pat. No. 6,992,452, entitled Dynamic Current Limiting, issued on Jan. 31, 2006, and hereby incorporated by reference. Continuing to refer primarily toFIG.7, if an input sensor has inaccuracies, for example, if a Hall sensor is inaccurate to 30°, or a resolver is inaccurate to 5°, the input sensor can override if the error between input sensor and estimate is too high. For example, if the Hall sensor measurement is 5° different from the raw input estimate, then the estimated value can be used. If the error is within 70°, the difference between the Hall sensor and the estimate can be clipped to a desired range, for instance an error threshold of 35-45°. The error value can be limited to a band around the angle. Other threshold errors could also be used as well. Referring now primarily toFIG.8, in some configurations, the feedback loop ofFIG.7may use a resolver instead of Hall sensors. Method10150can include estimating10100the rotor speed, and integrating10101the estimated speed to obtain an estimated rotor position. Method10150can further include receiving10202resolver digital signal56(FIG.4E) and calculating10203a measured position of the rotor based on resolver digital signal56(FIG.4E). Method10150can also include comparing10106the estimated rotor position to the measured rotor position from the resolver, and calculating10107a position error based on the comparison. Method10150can include changing10111the initial speed estimate based on the position error. In some configurations, obtaining an accurate measured rotor angle position can be aided by the use of limiters, i.e. current limiting methods and techniques, as well as deadbands based on resolver performance. Method10150can optionally include applying10105a deadband range to the measured rotor position which can transform the sawtooth error from the resolver, narrowing the measured input position value that can then be compared to the estimated position. The deadband range can compensate for the +5° and −5° degree limit of known natural error of a resolver. The deadband range can be 70-80% of this limit of natural error and therefore everything outside the error which exists within the deadband range may be essentially disregarded and/or moved towards a zero value. Error may also be limited by the use of techniques and methods for dynamically setting limits on the commanded current. Method10150can further optionally include if10108the error is greater than an error threshold, clipping10110the difference between the estimated position and the measured position. Method10150can further optionally include if10109the error is less than or equal to the error threshold, using 10109 A the estimated rotor speed. Referring now primarily toFIG.9, a difficulty in controlling the velocity based on input from Stirling engine11A (FIG.3) is that the torque τstof Stirling engine11A (FIG.3) has high spatial harmonics: τst==τ0+τ1f(θm) where τ0and τ1are functions of the slowly changing variables of head temperature and pressure, and f(θm) is a periodic function of angular position with respect to amplitude. At start-up of Stirling engine11A (FIG.3) the start-up torque τstis negative and typically varies significantly as Stirling engine11A (FIG.3) turns through a complete revolution. One of the pistons of Stirling engine11A (FIG.3) compresses gas during part of a revolution leading to more negative torque. In a later part of the revolution, the piston allows the gas to expand producing a less negative torque or even a positive torque. This change in torque over small angles i.e. τst≈−kθmcan lead to highly variable torque output. This effect can occur during the cycle of Stirling engine11A (FIG.3), but can be more significant during startup as the slow engine speed does not produce a flywheel effect to coast through the more negative torque periods. Once Stirling engine11A (FIG.3) is rotating, the inertia of Stirling engine11A (FIG.3) can be enough to maintain a more constant, but still somewhat variable torque. Following start-up, because the average torque of a cycle is positive and the time over which the torque harmonics act is inversely proportional to speed, the peak speed fluctuations are inversely proportional to average speed. But at start-up, a velocity controller (motor velocity control loop768(FIG.6)) for PMSM13(FIG.3) may exert a motor torque τmwhich could be greater than the peak negative “springy” torque generated in start-up in order to get Stirling engine11A (FIG.3) rotating. At start-up, it can be preferable that the motor torque τmincreases at a steady rate until it exceeds a lower threshold τmax_negand Stirling engine11A (FIG.3) accelerates. The rate of torque increase cannot occur too slowly otherwise start-up will take too long to start and the motor power board15(FIG.3) can risk overheating. If the torque increase is too fast, more motor torque than necessary may be produced and motor power board15(FIG.3) may not be able to tell how much torque is actually needed. Further referring primarily toFIG.9, motor power board15(FIG.3) could counteract or dampen the “springiness” of Stirling engine11A (FIG.3) at low speeds, and not use excess torque in accelerating Stirling engine11A (FIG.3). The costs of excess torque can be excess heating and excess power draw. Also, start-up and starting torque may exceed average running torque by a factor of two or three in some engines, so it could be start-up and starting torque that can dictate the peak power handling capability of motor power board15(FIG.3). A proportional-integral (PI) controller of speed can be used in some configurations. When Stirling engine11A (FIG.3) is rotating at sufficient speed, motor torque Tm can counteract the average torque of Stirling engine11A (FIG.3) and can maintain roughly constant speed. Motor power board15(FIG.3) can yield generated power from PMSM13(FIG.3) as a side effect of speed control. After Stirling engine11A (FIG.3) is running, the same PI controller gains used for start-up and starting states can be modified for use at running speeds. At running speeds, the gains can be low so that motor power board15(FIG.3) does not fight the oscillating torque fluctuations of Stirling engine11A (FIG.3). The gains can maintain a slowly changing generating torque to counteract the average torque from Stirling engine11A (FIG.3), while allowing moderate speed fluctuation. Referring still primarily toFIG.9, in some configurations, the differences between start-up and running torque can be addressed by utilizing a velocity controller state machine with three (3) states, although other numbers of states could also be determined. Power control board39(FIG.10) can initiate in start-up state870and, after predetermined first speed threshold872is exceeded, power control board39(FIG.10) can enter starting state874. When second predetermined speed threshold876is exceeded, power control board39(FIG.10) can shift to running state878. Referring now primarily toFIG.10, each of the three states can have a different integral gain Ki and different proportional gain Kp. The state transition condition for each speed threshold is |ωm|<thresh_lo or |ωm|>thresh_hi where ωn, is the measured or estimated motor velocity. A maximum speed command max_cmd parameter can limit the input to the velocity control loop768(FIG.6) to be within the range of +/−max_cmd. Kp and Ki can be tuned according to the desired behavior of each state. As an example of some parameter sets for entering start-up state870, entering starting state874, and entering running state878, method979can show these three states and transition values as follows: Start-up: Kp, Ki tuned for optimal torque ramp rate Thresh_lo=0 Thresh_hi=600 rpm Max_cmd=650 rpm (transition to starting state when speed >600 rpm just slightly greater than the transition threshold.) Starting: Kp, Ki tuned for fast speed control without overshoot Thresh_lo=0 Thresh_hi=900 rpm Max_cmd=950 rpm (transition to starting state when speed >900 rpm just slightly greater than the transition threshold.) Running: Kp, Ki tuned for low bandwidth speed control; Thresh_lo=600 Thresh_hi=spd_max (max detectable speed) Max_cmd=spd_max (no limit) Continuing to refer primarily toFIG.10, method979for controlling the speed of motor13(FIG.3) can include, but is not limited to including, entering981startup state870, tuning982the integral gain and the proportional gain for a steady state increase. If983the torque is greater than the maximum negative torque, and if984the motor speed is greater than 600 rpm, entering985starting state874. If983the torque is less than or equal to the maximum negative torque, returning to step982. If984the motor speed is less than or equal to 600 rpm, returning to step981. Method979can further include tuning986gain for speed control, no overshoot. If991the motor speed is greater than 900 rpm, entering987running state878. If991the motor speed is less than or equal to 900 rpm, returning to step986. Method979can also include tuning988gain for low bandwidth control. If989the motor speed is greater than 600 rpm, and if990the motor speed is greater than a maximum detectable speed, returning to running state987. If989the motor speed is less than or equal to 600 rpm, returning to step988. If990the motor speed is less than or equal to the maximum detectable speed, entering981start-up state870. Referring now primarily toFIG.11, with respect to three operating states, method150for producing DC power for a load can include, but is not limited to including, starting151an engine using power supplied by a relatively small power supply supplemented by a capacitor bank, providing153output from the engine to a generator, producing155alternating current (AC) power by the generator, converting157the AC power to direct current (DC) power, disabling159output of the DC power during a first set of pre-selected conditions, limiting161a rate of change of current of the DC power during a second set of pre-selected conditions, reducing163conducted and radiated emissions of the DC power, disconnecting165the DC power from the load under a third set of pre-selected conditions, and providing167the DC power to the load. Continuing to refer primarily toFIG.11, method150can optionally include controlling velocity of the motor by a motor drive power board as commanded by a system control board via a power control board, and inhibiting current flow from the motor drive power board to the capacitor bank. Method150can further optionally include powering, by a second power supply at the starting up of the engine, system control electronics. Method150can still further optionally include shunting excess of the DC power in the form of heat produced by the Stirling engine into a shunt load and heating water with the heat. Method150can also optionally include controlling velocity of the motor by a motor drive power board and the generator. The first set of pre-selected conditions can optionally include, but is not limited to, overcurrent and ground fault conditions. The second set of pre-selected conditions can optionally include, but is not limited to including, abnormal conditions. The third set of pre-selected conditions can optionally include, but is not limited to including, an abnormal overcurrent condition. Disconnecting the DC power can optionally include shunt tripping a DC output breaker during an arc fault condition. Method150can optionally include providing the DC power to an igniter power board, a pump/fan/blower drive, an engine control I/O PCB, a system control PCB, and a power control PCB. Referring now primarily toFIG.12, one alternative to the above parameters is to override motor speed in all states besides the running state, instead of limiting it. Controlling the motor speed with a feedback PI loop, for example, on the motor speed depends on varying instantaneous motor speed over each revolution during starting as torque3001varies. Thus, in some configurations, an adaptive estimate of the amplitude and phase of speed fluctuation using low pass filtering (LPF)3101(FIG.13) can remove noise and thus subtract out as much of the fluctuation as possible, so that the PI loop does not need to respond to this fluctuation. Referring now primarily toFIG.13, the amplitude and phase may change very slowly, so quadrature demodulation may allow amplitude component resolution. Speed signal3103can be filtered to remove frequencies much higher than the speed ripple. Speed signal3103can be passed through a synchronous demodulated algorithm to produce Kc3105and Ks3107. The time varying values of Kc3105and Ks3107are the sinusoidal components of speed ripple that are at 90° from each other. Note that the low pass filters3101of the demodulator algorithm and the computation3109of ωmare different. The ripple-free or average speed is ωm′=ωm−Kc*cos(ωm)−Ks*sin(ωm) and the control speed is based on this estimate of ωm′. In a further configuration of motor control architecture, a vector control motor which may use variable frequency drives to control the torque, and thus the speed of 3-phase electric motor/generators by controlling the current fed to the machine, can be used. Different motor types are possible such as induction motors, permanent magnet synchronous motors (PMSM), and synchronous reluctance motors (Synch Rel) for instance with PMSM motors used by way of example for some configurations. In PMSM motors, the permanent magnets on the rotor are pulled in one direction or another by the relative position of the stator and rotor fields. Because the rotor field is fixed in orientation with the rotor, torque production and control requires knowledge of rotor position. Referring again primarily toFIG.6, there are a number of ways to write the torque equation for PMSM motor13, for example: Vdq=Keωm=RIdq+LdqdIdqdt+JωeLdqIdq where V is the terminal voltage, I is the motor current, Keis the back-emf constant, ωmis the mechanical rotational frequency of the rotor, ωe=ωmP/2 is electrical rotational frequency of the rotor, P is the number of poles, and L and R are the inductance and resistance. The equation is written in the rotor (dq−) reference frame with J=[0-110],Vdq=[VdVq],Idq=[IdIq],Ldq=[Ld00Lq],Ke=[02λmP] where λm=rotor magnet flux, which may then be used to write out the state equation in scalar form as Vd=RId-ωeLqIq+LddIddtVq=Keωm+RIq+ωeLdId+LqdIqdt The cross terms (with ωe) result from reference frame rotation (similar to Coriolis “force”); in the stator (xy−) reference frame, they are not present but the LddIddt and Keωmterms are present. The cross terms can couple the two equations at nonzero speed. The torque equation is τm=32(P2(Lq-Ld)IqId+KeIq)=32P2((Lq-Ld)IqId+λmIq) which includes a reluctance torque term due to rotor saliency (Lq≠Ld) and an alignment torque term. In some configurations PMSM motor13with a torque control loop structure could utilize a sine-drive or a six-step drive. The six-step drive could be a good match for digital Hall sensors. Utilizing a sine-drive, the choice of torque loop may be decoupled from the choice of position/speed sensor. Referring now primarily toFIG.14A, power controller39(FIG.3) can communicate with motor power board15(FIG.3), DC output board19(FIG.3), and igniter board31(FIG.3) to control motor13(FIG.3) as well as Stirling engine11A (FIG.3). CAN bus313(FIG.4J) can be used to, for example, but not limited to, enable communications among the various subsystems in power controller39(FIG.3), system controller53A (FIG.3), and various control actuators and/or receive feedback from various sensors and ensure that the appropriate messages are timely delivered to the appropriate subsystem to be evaluated and acted on by power controller39(FIG.3). Each message from an electronic control unit of power controller39(FIG.3) can be transmitted onto a data bus in which message conflicts can be resolved using standard protocols. Conforming to Part B of the CAN specification 2.0, 1991, a CAN message can include, but is not limited to including, 29 bits of message identifier, four bits of a data length field, and 0-8 bytes of data, among other fields. In some configurations, data can include, but is not limited to including, critical control flags, system faults/status, power stage faults, overvoltage regulator faults/status, motor drive faults/status, buck/boost faults/status, inverter faults/status, and controller system information. In the 29-bit extended mode message identifier, bits 0-28, message priority11120can be defined by the highest three bits—bits 28, 27, 26—with zero being the highest priority. Priority of messages having equal message priorities11120can be arbitrated by the contents of other bits in the message identifier. In some configurations, the priority zero (highest) can be used only for the most critical control and alarm functions. The highest bits can be used to define priority because, similar to standard arbitration protocols, if two messages are transmitted at the same time, as soon as a recessive (1 value bit) is seen for a lower priority message transmission, the message is stopped and a higher priority message with a dominant (0 value bit) is sent unimpeded to CAN bus313(FIG.3). For example, a message with the bits28,27and26set to zero can be the highest priority message that may be sent. On the other hand if these same bits are all set to 1, this can be the lowest priority that may be set for a message, but a recessive value at any bit location could stop transmission of the message if another message being transmitted has a dominant bit value at the same location. The impeded message can then be transmitted based on its priority after the higher priority message. This can provide for a total of eight different priority combinations or definitions where each bit is either 0 or 1 in binary notation, and with three bits the total number of permutations is 2×2×2=8 combinations or definitions for message priority11120. Continuing to refer primarily toFIG.14A, the standard CAN protocol does not include system configuration information, for example, information about the destination of a message. Instead, all messages are sent to all nodes. Nodes can decide whether to act upon data in the message based on the contents of the message. Thus, any number of nodes can receive the message and act upon it simultaneously. After transmission of the message priority11120, the remainder of the bits can be utilized as the message definitions body themselves and these definitions can be divided into a series of groups, for example, but not limited to: system group11122defined by three bits—25, 24, 23—functional group11124defined by four bits—22, 21, 20 and 19—module group11126defined by eight bits—18-11-device group11127defined by three bits—11, 10, and 9—and message group11128defined by eleven bits—bits 10-0. Message priority11120and the groups do not have to contain these specific bits or this exact number of bits described here, other allocations of bits may be provided as well. However, the CAN protocol interprets any zero bit value to trump any non-zero bit value in terms of message priority11120. Therefore, assigning bit values to members of groups can require evaluation of priority. Continuing to still further refer primarily toFIG.14A, system group11122can include, for example, bit settings to identify power controller39(FIG.3), for example, the setting of bits 23-25 to zero. Other configurations for power controller39(FIG.3) may be assigned using other bit value combinations. Functional group11124can identify subgroups power production, power transmission, power consumption, energy storage, and utility by unique bit settings. In some configurations, power production messages can be assigned the highest priority, which means setting of bits19-22to zero. Other subgroups may be defined as well. Module group11126can identify various power production, transmission, and consumption devices, for example engines such as diesel and gas generators, thermal engines such as Stirling engines, wind turbines, photovoltaic systems, fuel cells, and for energy storage with battery storage systems and battery charging systems. In some configurations, Stirling engine11A (FIG.3) can be assigned the highest priority. In some configurations, there may be over 2000 messages defined in message group11128, and any given message may be identified as important to any module in Module Group 11126. These specific and unique identifiers not only readily allow orderly communication of messages across CAN bus313(FIG.4J), but also tell the controllers what the message is, and may contain associated measured or sensed data which can permit the controller to determine appropriate commands for controlling the various modules or system components. Device group11127can identify one of eight possible devices on the bus with otherwise identical attributes of system, function, and model groups. Referring now primarily toFIG.14B, in some configurations, a message identification field can include priority field11120occupying the most significant of the 29-bit CAN message header to ensure that critical system control messages do not get superseded by less important messages. Priorities identified in some configurations can include, but are not limited to including, National Instruments rugged and reconfigurable control and monitoring system (cRIO) to power electronics messages (highest priority, i.e. priority 0), power electronics to cRIO (priority 2), cRIO to power electronics variable frequency device messages (priority 3), and power electronics variable frequency device to cRIO messages (priority 4). Referring now primarily toFIGS.14C-G, in some configurations, system group11122(FIG.14C), functional group11124(FIG.14D), module group11126(FIGS.14E and14F), and device group11127(FIG.14G) can include various bit configurations. Referring now primarily toFIGS.14H-14O, in some configurations, message characteristics for messages transferred among elements of the system can include critical messages (FIG.14H) priority two messages (FIGS.14I-14L), and priority three and four messages (FIGS.14M-14O) For example, critical control flags1122A for a 3-phase Stirling generator have message ID 0x00005002, and message index two. Priority two power electronics messages (FIGS.14I-14L) can include 3-phase Stirling generator motor watts and brake watts messages1122B, message ID265, for example. Priority three and four power electronics messages for utility function, VFD module, and VFD combustion device (FIG.14M) can include, for example, control flags1122C, message index 2, and speed1122D, message index256. Priority three and four power electronics messages for utility function, VFD module, and VFD water pump (FIG.14N) can include, for example, control flags, message index two and speed message index256. Priority three and four power electronics messages for utility function, VFD module, and VFD water radiator (FIG.14O) can include, for example, control flags1122E, message index 2 and speed1122F message index256. Referring now primarily toFIG.15A, critical control flags, message ID 0x00005002, message index 2, can occupy two 16-bit words (four bytes) with bits set by system control board53(FIG.8), for example. System control board53(FIG.3) can send a CAN message having specific bits set to power control board39(FIG.3) which in turn could use the information in the critical control flags to control motor power board15(FIG.3), igniter power board31(FIG.3), and DC output board19(FIG.3). For example, if power control board39(FIG.3) receives a CAN message having data including message ID 0x00005002 followed by a 16-bit word with at least bit one 1122G set, power control board39(FIG.3) could force itself to a faulted state. Likewise, if power control board39(FIG.3) receives a message according to CAN bus protocol having data including message ID 0x00005002 followed by a 16-bit word with at least bit two 1122H set, power control board could enable engine controller49(FIG.3). Message index2information is also shown inFIG.14H. Referring primarily toFIG.15B, a first 16-bit word for system faults/status could be included in the data section of the CAN message for message ID 0x0800510C, message index268. The word could, for example, but not limited to, communicate status of various devices, for example, but not limited to, shunt17(FIG.4H). Message index268information is also shown inFIG.14J. Referring primarily toFIG.15C, VFD message details corresponding to utility VFD, VFD radiator (FIG.14P) message information is shown. In general, each CAN message in the VFD message group can include four words of data, the exemplary contents of which can include, in some configurations, messages relating to speed, status, current, and voltage, for example. Referring now primarily toFIG.16, measured or sensed data and other arbitrary information from embedded power control board39can be collected in real-time to, for example, but not limited to, diagnose errors and/or debug issues. Digital signal processor (DSP)19140for example can operably communicate with at least one device such as computer or PC19142via communications link19144. Communications link19144can be, but is not limited to being, a serial port or UART, Ethernet, Bluetooth wireless, or can accommodate other communication protocols. A relevant characteristic of communications link19144is that there can be a stream of information flowing in each direction. A protocol can define several different types of packets of information for each direction of the protocol. DSP19140can transmit packets to the PC19142, some of which may include broadcast of arbitrary data. PC19142can transmit packets to the DSP19140, some of which are commands to read or write data in DSP19140, including data that can determine which data DSP19140should be broadcasting to PC19142. This can allow for changes at any time as to which data PC19142receives. In addition there can be other packets that can allow DSP19140and PC19142to determine whether communication link19144between the two is maintained. If communication link19144is interrupted and resumed, a status check of communication link19144between each of the devices and links with other devices within the system can be performed with diagnostic checks that can determine if there are any changes in performance of any of the devices. Further executable programs such as DiagUI19200may be installed on PC19142and may use communications link19144to transmit and receive data as discussed herein. Referring again primarily toFIG.16, the information available to both DSP19140and PC19142can include how to communicate via a protocol, as well as how to build metadata including the following data: (1) date and time the DSP program was compiled, (2) a unique 128-bit ID generated per the standard Universally Unique Identifier (UUID) mechanism, (3) a program identifier (a human-readable string to distinguish varying types of DSP programs), (4) a version number that can corresponds to the version of the source code stored in a source control repository such as SURROUND SCM®, CLEARCASE®, and/or SUBVERSION®. Metadata can be stored within executable file19148that can be generated at compile time. DSP19140can be programmed using executable file19148. PC19142can have access to executable file19148, as well as access to build metadata. Executable file19148can also have a DSP symbol table so that given the name of a variable on DSP19140that has a fixed memory location, PC19142can determine what type of variable it is (e.g. 16-bit unsigned integer, 32-bit pointer, structure, union, etc.), and where it is located in the DSP's memory. Continuing to refer primarily toFIG.16, DSP19140may use, for example, but not limited to, a 2.34375 Mbaud serial port with the standard UART configuration of one start bit, eight data bits, and one stop bit per byte, or 234,375 bytes per second maximum throughput in each direction. If a diagnostic kernel routine on the DSP executes at a 10 kHz rate, then the diagnostic kernel may send and receive at most 23.4 bytes on average; data that exceeds that length can be enqueued or dequeued in a buffer. Each packet19150can include header19152, message digest19154, data (varies depending on the type of packet)19156, and delimiting mechanism19158. Delimiting mechanism19158can provide a determination of when one packet ends and the next packet begins. Consistent overhead byte stuffing (COBS) can provide a fixed overhead of two bytes for packets of less than 255 data bytes (one extra byte per packet for encoding, and one extra byte for delimiting), thereby efficiently encoding and decoding each packet. Message digest19154can provide a means for detecting transmission errors by adding, at the end of packet19150, extra bytes that are a function of the previous bytes in the packet, so that a receiver of the packet may compute the same message digest19154, and if it matches the one transmitted, there is high probability that the packet19150has arrived without errors. A 16-bit cyclic redundancy check (CRC) can be used in some configurations as a message digest, adding two bytes overhead. Continuing to still further refer primarily toFIG.16, before transmission, packet19150can be formed as a raw data packet, which can have the 2-byte CRC appended to it, and can be encoded using COBS, for example. The header can include, but is not limited to including, at least one byte at the beginning of the raw data packet that can determine which type of packet it is. Each header19152can include, but is not limited to including, a tag that is a prefix code, i.e. within the set of possible header tags, in some configurations, no tag is the prefix of any other tag (e.g. the header tags 0xff, 0xfe00, and 0xfe01 can be a valid set, but the header tags 0xff, 0xff00 can be an invalid set because 0xff is a prefix of 0xff00). Using this method,256valid one byte header tags may be developed and more if more than one byte for some of the header tags is used. In some configurations, the overhead for packet encoding can be at least one byte for the header tag, two bytes for the CRC, and two bytes for COBS, or five bytes per packet. Continuing to refer primarily toFIG.16, there can be a number of different packet types that can be used for communication protocols. In some configurations, a ping packet can be sent from DSP19140to PC19142on a periodic basis, or in response to a ping request packet. The ping packet can contain a counter incremented each time a ping packet is sent (this allows the PC to detect missing packets), a 16-bit timestamp, and critical message counters (described herein). A ping request packet can be sent from PC19142to DSP19140on an arbitrary basis. For “keepalive” purposes, a predetermined timeout of approximately 100 msec can be used both for ping packets and ping request packets. Both PC19142and DSP19140can transmit the corresponding packet during each timeout interval, and if a timeout interval elapses without receiving the corresponding packet, something could be wrong and the communications connection could be considered to be interrupted. A memory read request can be sent from PC19142to DSP19140on an arbitrary basis. The memory read request can include an 8-bit read request ID, eight bits of flags, an 8-bit byte count, and a 32-bit starting address. The flags can include one bit determining whether the address points to absolute memory or “virtual memory” (described herein). Upon receiving the memory read request, DSP19140can read the requested memory and respond with a memory read response. A memory read response can be sent from DSP19140to PC19142in response to a memory read request. The memory read response can contain the 8-bit read request ID, and data corresponding to the memory read request. The request ID can enable the PC19142to request several different pieces of data and later match the responses with the requests. If a read response is not received, PC19142may re-issue the read request. A memory write request can be sent from PC19142to DSP19140on an arbitrary basis. The memory write request can contain an 8-bit critical message count, eight bits of flags, a 32-bit starting address, and data. The flags can include one bit indicating whether the address points to absolute memory or virtual memory. Upon receiving the memory write request, DSP19140can write the requested memory. A critical message count can be maintained by DSP19140and reported in a ping packet. For packet types that are considered critical messages (including memory write requests), DSP19140can ignore any message where the received critical message count does not match its internal counter. If the critical message counts match, DSP19140can increment the critical message count and act upon the received message. DSP19140and PC19142can stay in sync with respect to critical messages based on the protocol described herein. If messages are improperly received, they can be ignored, and PC19142may detect the improper reception and re-send messages. If the same message is received twice, the duplicate message can elicit a single reaction. A broadcast packet can be sent from DSP19140to PC19142. The broadcast packet can include a packet ID header tag, an 8-bit counter field, and data. Header tags 0x00-0x7f for broadcast packets can be reserved, leaving tags 0x80-0xff for the packet types described above as well as application-specific packets. A broadcast packet can be sent once each time a diagnostic kernel of DSP19140executes, and when DSP19140has detected valid communications from PC19142(e.g. it has received a ping request packet within its timeout). Header tag19152can allow twenty-eight different sets of data to be sent. Continuing to still further refer primarily toFIG.16, each data set may have arbitrary data, to the extent that it may fit within the available bandwidth. In some configurations, twenty-three bytes can be available with four bytes overhead for COBS and the CRC—one byte for the packet header tag and one byte for the counter field—leaving seventeen bytes for data. In some configurations, fourteen bytes (seven 16-bit words) can be used. An 8-bit counter field can include a 3-bit change counter and a 5-bit tick count. The change counter can be incremented once each time DSP19140executes a memory write request that could affect the contents of the broadcast packet, so that, for example, if PC19142sends a request to DSP19140to write memory, the contents of the broadcast packet could be changed, and PC19142may determine exactly when DSP19140is sending new data. The 5-bit tick count can provide a fine-grained timestamp for the data that was sent. The 5-bit tick count can allow for up to thirty-one broadcast packets to be lost while still maintaining a valid timestamp. Ping packet can include the same timestamp but can use a full sixteen bits. The combination of these two timestamps can allow PC19142to track timestamps even in the presence of missing packets, and can allow PC19142to extrapolate received data—data measured or sensed voltage—without DSP19140having to allocate large amounts of bandwidth. PC19142can include a copy of executable file19148containing a symbol file which can provide for PC19142to access the memory of DSP19140. Referring now primarily toFIG.17, certain items of data can be accessed in an area of virtual memory21164(FIG.16) where DSP19140(FIG.16) can translate a memory request from PC19142(FIG.16) to a memory address understood by DSP19140. These items of data can include, but are not limited to including, build metadata providing information about executable file19148(FIG.16). If the build metadata in executable file19148(FIG.16) does not match the build metadata received from DSP19140(FIG.16), then the absolute addresses found in the symbol table of executable file19148(FIG.16) may not be used reliably. Data items can also include session ID 21166, an arbitrary number created by PC19142(FIG.16) at each communication with DSP19140(FIG.16). To protect access to virtual memory21164(FIG.16), method2100can include, but is not limited to including, creating 2101, by PC19142(FIG.16), an initial unique session ID, and sending2103the session ID to DSP19140(FIG.16). DSP19140(FIG.16) can receive and apply 2105 session ID. If2123DSP19140(FIG.16) has been reset, DSP19140(FIG.16) can scramble2111session ID 21166. If2107PC19142(FIG.16) experiences a communications interruption (detected by, for example, ping packet timeouts), PC19142(FIG.16) can request2109session ID from DSP19140(FIG.16), and if2113session ID 21166 (FIG.16) has changed from a previous reading, then either DSP19140(FIG.16) has been reset, or PC19142(FIG.16) has been connected to a different DSP19140(FIG.16). PC19142(FIG.16) can then request2117executable files19148(FIG.16) from DSP19140(FIG.16), DSP19140(FIG.16) can send2119executable files19148(FIG.16), and PC19142(FIG.16) can receive2121executable files19148(FIG.16). If2113session ID 21166 (FIG.16) has not changed, PC19142(FIG.16) may assume that a temporary communications interruption has occurred between DSP19140(FIG.16) and PC19142(FIG.16) and can continue2115using executable files19148(FIG.16). Referring now primarily toFIG.18, data can also include broadcast metadata19146(FIG.16) which can include CPU metadata, including flags that identify (1) whether the CPU uses 8-bit or 16-bit memory words, (2) whether the CPU uses 16-bit or 32-bit pointers for memory addressing, (3) whether multiple-word quantities are most-significant-word first or least-significant-word first, and (4) whether memory address alignment is 1-byte-aligned, 2-byte-aligned, 4-byte-aligned, or 8-byte-aligned. DSP19140can use a particular block of virtual addresses to determine which data are sent over broadcast packets, including, in some configurations, schedule table22184, data palette22186, and a few counters. Broadcast packet IDs22182can correspond to rows of schedule table22184. Schedule table22184can provide to DSP19140the information to send for each broadcast packet ID 22182. Each row of schedule table22184can include, but is not limited to including, two pairs of data, A data22187and B data22189, with each pair consisting of index22188and count22190referring to an entry in broadcast data palette22186. Data palette22186can include addresses of, for example, 16-bit data words that are written by PC19142(FIG.16). Schedule table index22188and count22190can be used as a starting offset and a starting count respectively within data palette22186. For example, if row 0 of A data22187contains index 1, count 3, and row 0 of B data22189contains index 80, count 2, then broadcast packet id 0 can send the contents of data palette addresses #1, #2, #3, #80, and #81. If schedule table row 1 contains A data22187index 30, count 5, and B data22189index 45, count 1, then the broadcast packet id 1 can send the contents of data palette addresses #30, #31, #32, #33, #34, and #45. A data22187can, for example, but not limited to, be several words of data that can be broadcast at, in some configurations, every 10 kHz cycle, or every other 10 kHz cycle, whereas B data22189can, for example, but not limited to, be one or two words of data of a long list of data, thereby creating a “fast” set of a few data words, and a “slow” set of many data words, making for a flexible system for data transfer. Continuing to refer primarily toFIG.18, if PC19142(FIG.16) can set the contents of data palette22186and schedule table22184, then PC19142(FIG.16) can interpret the contents of each broadcast packet and can associate the contents with the appropriate memory locations in DSP19140(FIG.16) that PC19142(FIG.16) selects. In some configurations, DSP19140(FIG.16) can cycle through rows 0 to SCHEDPERIOD-1 of schedule table index22188, where SCHEDPERIOD can include a counter located, for example, in the virtual address space and may be set by PC19142(FIG.16). It is possible for DSP19140(FIG.16) to use any arbitrary ordering of rows (e.g. 0, 1, 0, 2, 0, 3, 0, 4, 0, 1, 0, 2, 0, 3, 0, 4, etc) of schedule table index22188. If row # of schedule table index22188can be transmitted as packet ID22182of broadcast data packets, PC19142(FIG.16) may not need to know about this ordering to be able to interpret the ordering correctly. In some configurations, a mechanism can be provided that can set up a desired ordering. Referring again primarily toFIG.16, debugging/diagnostic system and user interface (DiagUI)19200can indicate and relay engine operational data from engine11(FIG.4G) to technicians, operators and engineers. Operational data for engine11(FIG.4G) may be collected from a plurality of engine sensors and from DSP19140and engine control I/O PCB49(FIG.3). The operational data may be optionally stored in a memory storage device, or relayed directly through DiagUI19200to the operator. DiagUI19200can enable an operator to read and write data to DSP19140of engine11(FIG.4G), and can monitor engine11(FIG.4G) and DSP19140, and attend to data logging of predetermined operational data to evaluate and analyze operational conditions of engine11(FIG.4G). DiagUI19200can use for example, but not limited to, a high bandwidth data communication channel in real time, and/or DiagUI19200can buffer data within a given time frame, and/or can take a snapshot of sensor data at some point in time of the operating data from engine11(FIG.4G) and present the data in a coherent form for analysis. DiagUI19200can read/write data to and from desired variables of engine control I/O PCB49(FIG.3). The read/write function can be an on-demand task for DiagUI19200and can be a one-time task, meaning although repetitive from the operator's perspective, the read/write function to any particular variable can be begun and completed in a short one-time task. DiagUI19200can monitor the proceeding engine operations by displaying desired variable values on the screen, for example, through immediate evaluation of engine operation, and through recording of data for later analysis. Reading and writing of variables for example can include determining and selecting a desired variable to write to, for example, a control parameter for engine11(FIG.4G) that the operator desires to modify such as a voltage gain threshold limit. Monitoring of a desired variable can include for example, but not limited to, displaying a real time motor current in a table of DiagUI19200and then logging that value to a data file for subsequent analysis. In some configurations, any variable from executable file19148can be monitored and logged. The system can translate, for example, a variable name to an address by reading executable file19148. Referring now primarily toFIG.19A, to associate specific unit definitions with program variables of DSP19140(FIG.16), typedef declarations can be used, for example, but not limited to, to identify a variable by the unit of measure that it represents. Each variable in DSP19140(FIG.16) can be associated with a variable type, e.g. uint32_t, an unsigned 32-bit, int16_t, signed 16-bit, and uint8_t, unsigned 8-bit. The typedef declaration can be a synonym used in place of a data type to associate that variable with specific data, such as a voltage, current, temperature, etc. Typedef int int16_t can create type int16_t32100as an equivalent to type int32103. Typedef int16_t foo and typedef int16_t bar can create types foo32105and bar32107respectively as equivalent to type int16_t32101and type unsigned long32117. Typedef unsigned long unit32_t and typedef unsigned long baz can create types uint32_t32115and baz32111respectively as equivalents to type unsigned long32117. Typedef unit32_t blam can create type blam32113as equivalent to type unit32_t32115and type unsigned long32117. Typedef bar quux can create type quux32109as equivalent to type bar32107, and equivalent to type int16_t32101, which is equivalent to type int32103. Any variable or set of variables may be defined; for example a set of current and voltage readings may be defined as current1_S16, voltage1_S16, temp1_S16, current2_U32, voltage2_U32, etc. with each of these unit types resolved, in some configurations, to, for example, but not limited to, a C/C++ native data type. Variable names may be created with specific metadata such as an identifier, for example a suffix that can include the unit type. The identifiers may be grouped as members into a data structure providing for the group of identifiers to be called under one name, the name being a new valid type name the same as the fundamental types such as int or long. The structure name may be used in a particular namespace context allowing for variables having the special group identifier to be recognized. Referring now primarily toFIG.19B, in some configurations, a typedef declaration can be made for each identifier and these identifiers can be grouped under a data structure with a special pre-arranged name such as Unit_Base_Marker. A typedef declaration can also be made for each variable to point to each of the appropriate identifiers. Each variable string can include the unit base marker suffix and may be recognized from other similarly named variables that are not within the same context as those variables of the Unit_Base_Marker type. For example: typedef uint16_t U16;typedef int16_t S16;typedef uint32_t U32;typedef int32_t S32;struct _Unit_Base_Marker_ {U16 x000;S16 x001;U32 x002;S32 x003; . . . } These definitions can provide for a variable string having raw value data to be automatically associated with a unit definition and thereby convert the raw data value to an engineering value using a conversion factor. In some configurations, DiagUI19200(FIG.16) can provide a set of global variables that can each include a unit name, a static address, and unit type. Using the specific address information, DiagUI19200(FIG.16) can extract data from DSP19140(FIG.16), can associate these data with the specific global variable having that address information, and can create a variable string that can include the unit name, identifier unit type, and the DSP data. For example, a variable string can include Voltage1_S16Vbat. Using typedef and the stored metadata defining the string, DiagUI19200(FIG.16) can enable DSP data to be associated with unit definitions. DiagUI19200(FIG.16) can read the DSP output data file with symbol string information to detect a program variable's type. DiagUI19200(FIG.16) can compare the typedef chain to the data structure type for the special Unit_Base_Marker_and, if the typedef chain is defined within the context of that data structure type, DiagUI19200(FIG.16) may associate a unit definition with the variable. If the variable type is descended from one of a unit base type, DiagUI19200(FIG.16) can analyze the name to determine if the name ends in one of the members of the data structure, in this example one of the suffixes_S16, _U16, _S32, _U32. If the variable name contains one of the suffixes, DiagUI19200(FIG.16) can resolve the variable data to remove the identifying suffix from the unit name to determine the global variable. For example, the variable “Voltage1_S16Vbat” can have an inferred unit name “Voltage1”. DiagUI19200(FIG.16) can search the unit name for the encoded unit definition string, for example “732.0Q15V”. DiagUI19200(FIG.16) can interpret the unit definition as 215counts=732.0V and this data can be associated with a program variable, Vbat, thereby converting the raw value DSP data to an engineering value. Continuing to refer primarily toFIG.19B, in some configurations, DiagUI19200(FIG.16) may change the unit definition for any variable in the system any time DiagUI19200(FIG.16) is turned on including, but not limited to, while the system is running. In some configurations, DiagUI19200(FIG.16) may update the unit definitions for variables when it is turned on or when it is reinitialized. In some configurations, DiagUI19200(FIG.16) may be programmed to update the unit definitions for variables at any time including, but not limited to, when a user requests DiagUI19200(FIG.16) to update the unit definitions for variables, at specific time intervals, and whenever a unit definition for a variable has been updated using DiagUI19200(FIG.16). In some configurations, when a unit definition of a variable has been changed using DiagUI19200(FIG.16), DSP19140(FIG.16) can update the unit definition of that variable and any unit definitions of variables dependent on the unit definition of that variable. For example, the unit definition of power may depend on the unit definitions of voltage and current. Therefore if the unit definitions of voltage and/or current are changed, DSP19140(FIG.16) can update the unit definitions of voltage and/or current, and also the unit definition of power. In some configurations, various temperatures in the system may be measured including, but not limited to, battery temperature, motor temperature, ambient air temperature in various places relative to system100(FIG.4G), and the heat sink temperature. In some configurations, if a battery is included, the battery temperature may alter the behavior of a battery charging algorithm. In some configurations, the motor and/or heat sink temperature measurements may be used to measure how much power is flowing in the system. In some configurations, the motor and/or heat sink and/or ambient air temperature measurements may be used as a basis for throttling down the engine or lowering the current limits in the system to reduce heat to safe levels. In some configurations, the motor and/or heat sink and/or ambient air temperature measurements may be used as a basis for running the system at less than the optimal power point to allow the system to cool. In some configurations, the motor and/or heat sink and/or ambient air temperature measurements may be used to measure the efficiency of the cooling system. Configurations of the present teachings can be directed to computer systems for accomplishing the methods discussed in the description herein, and to computer readable media containing programs for accomplishing these methods. The raw data and results can be stored for future retrieval and processing, printed, displayed, transferred to another computer, and/or transferred elsewhere. Communications links can be wired or wireless, for example, using cellular communication systems, military communications systems, and satellite communications systems. Parts of system100(FIG.4G), for example, can operate on a computer having a variable number of CPUs. Other alternative computer platforms can be used. Some configurations can be directed to software for accomplishing the methods discussed herein, and computer readable media storing software for accomplishing these methods. The various modules described herein can be executed on the same CPU, or can be executed on different CPUs. In compliance with the statute, some configurations have been described herein in language more or less specific as to structural and methodical features. It is to be understood, however, that some configurations are not limited to the specific features shown and described, since the means herein disclosed comprise various forms of putting some configurations into effect. Methods9150(FIG.7),10150(FIG.8),979(FIG.10),150(FIG.11), and2100(FIG.17) can be, in whole or in part, implemented electronically. Signals representing actions taken by elements of system100(FIG.4G) and other disclosed configurations can travel over at least one live communications network20(FIG.4G). Control and data information can be electronically executed and stored on at least one computer-readable medium. The system can be implemented to execute on at least one computer node in at least one live communications network. Common forms of at least one computer-readable medium can include, for example, but not be limited to, a floppy disk, a flexible disk, a hard disk, magnetic tape, or any other magnetic medium, a compact disk read only memory or any other optical medium, punched cards, paper tape, or any other physical medium with patterns of holes, a random access memory, a programmable read only memory, and erasable programmable read only memory (EPROM), a Flash EPROM, or any other memory chip or cartridge, or any other medium from which a computer can read. While the present teachings have been described above in terms of specific configurations, it is to be understood that they are not limited to these disclosed configurations. Many modifications and other configurations will come to mind to those skilled in the art to which this pertains, and which are intended to be and are covered by both this disclosure and the appended claims. It is intended that the scope of the present teachings should be determined by proper interpretation and construction of the appended claims and their legal equivalents, as understood by those of skill in the art relying upon the disclosure in this specification and the attached drawings. | 97,563 |
11859590 | DETAILED DESCRIPTION The present disclosure is directed to an intelligent battery pack associated with a starting system for an internal combustion engine used with various types of outdoor power equipment. The drawing figures depict the use of the intelligent battery pack with a lawn tractor. However, it should be understood that the battery pack and starting system could be utilized with other types of outdoor power equipment such as with lawn mowers, riding tractors, snow throwers, pressure washers, tillers, log splitters, zero-turn radius mowers, walk-behind mowers, riding mowers, stand-on mowers, pavement surface preparation devices, industrial vehicles such as forklifts, utility vehicles, commercial turf equipment such as blowers, vacuums, debris loaders, overseeders, power rakes, aerators, sod cutters, brush mowers, sprayers, spreaders, etc. FIG.1illustrates a riding lawn tractor10that includes a mowing assembly11mounted beneath a vehicle chassis12supported by four wheels14. The lawn tractor10includes an internal combustion engine (not shown) that powers both the rear drive wheels and the mower blade contained within the mowing assembly11. A steering wheel16allows an operator positioned in the seat18to control the movement of the lawn tractor10, as is conventional. In the embodiment shown inFIG.1, the lawn tractor10includes an ignition switch19that is used by the operator to start operation of the internal combustion engine. The ignition switch19could be a three position key switch or could be a push-button. The operation of the ignition switch19will be detailed below. The details of the lawn tractor10shown inFIG.1are meant of illustrative purposes only, since the lawn tractor10could have various different operator controls and physical configurations while falling within the scope of the present disclosure. FIG.2illustrates one possible embodiment of a battery pack40constructed in accordance with the present disclosure. The battery pack40includes a two-piece outer battery housing22that includes a bottom portion24and a top portion26. The top portion26includes a power level display28that includes a plurality of individual indicator lights30. Although the embodiment shown inFIG.2includes multiple indicator lights30, it is contemplated that the multiple indicator lights30could be replaced by a single LED that changes color depending upon the charge stored on the internal battery cell. As an example, the indicator lights30could be replaced by a single LED that changes color from green to yellow to red, depending upon the state of charge on the internal battery pack. Alternatively, the multiple indicator lights30could be replaced by a single LED that flashes, remains on in a steady state, or is turned off depending upon the charge level of the battery pack40. Such embodiment would allow for a single color LED. In the embodiment shown inFIG.2, the battery pack40includes six individual battery cells34that are organized and connected to each other and are contained within the outer battery housing22, as will be described in greater detail below. In the embodiment shown inFIG.2, the six individual battery cells34are stacked in two rows each including three cells. However, it is contemplated that other configurations could be utilized while operating within the scope of the present disclosure. The size of the outer battery housing22is configured to accommodate the six battery cells34, which provides for additional interior space for the charging circuit, the switching circuit, and the control circuit to be described below. FIG.3illustrates the circuit board36that includes the indicator lights30. In addition, the circuit board36includes an activation switch38that allows the user to test the charge of the battery pack32. For example, the indicator lights30may only provide an indication to the user of the charge of the battery pack32when the activation switch38is actuated by the user. The circuit board36is further shown to include a control circuit42, which will be described in more detail below. In the embodiment illustrated, each of the individual battery cells34of the battery pack40can be one of two different types of storage cells. In one embodiment, each of the cells34is a common lithium ion battery, referred to as an NMC (nickel magnesium cobalt) battery. The NMC battery cells may be configured to have a pre-defined voltage level. For example, each of the NMC battery cells in battery pack34may have a rating of 3.6 volts. In other embodiments, each of the battery cells34may be another type of lithium ion battery referred to as a lithium iron phosphate cell (LiFePO4, LFP). A lithium iron phosphate (“LFP”) battery is a type of lithium ion rechargeable battery that is typically used for high power applications. An LFP battery allows for reduced protection circuitry as compared to an NMC battery, and typically offers a longer usable life, better power density, and is inherently safer. An LFP battery has a typical maximum charge capacity of 3.2 volts each in the embodiment shown inFIG.3. In the present disclosure, both the LFP and NMC battery cells will be referred to as lithium ion battery cells. In the embodiment illustrated, the six individual battery cells34of the battery pack40are believed to be able to provide enough current to start an internal combustion engine of the lawn tractor many times, to increase the number of starting attempts between required charging of the battery pack32. However, it is contemplated that other battery cell arrangements may be utilized to provide sufficient power to starter motors of various sizes and configurations. FIG.4illustrates the operating configuration of a battery pack40according to some embodiments. The battery pack40is shown inFIG.4as including a series of individual battery cells34connected in series. However, it should be understood that a different number of battery cells34could be utilized and that the battery cells could be connected in series, parallel or series-parallel configurations depending upon the output requirements from the combination of the battery cells34. The battery pack40includes the control unit42within an outer housing44schematically shown inFIG.4. The control unit42is positioned to receive inputs from other systems associated with the operation of the internal combustion engine and to control operation of multiple switches as will be described in greater detail below. As illustrated inFIG.4, the battery pack40includes an ignition input terminal46that is connected to the ignition circuit48, including an ignition coil, from the internal combustion engine. An ignition signal received at the ignition input terminal46is fed into the RPM input pin50of the control unit42. The ignition signal from the ignition circuit48will include a series of pulses that correspond to the rotational speed of the internal combustion engine. By monitoring the pulses present at the RPM input pin50, the control unit42will be able to determine whether the internal combustion engine is running or whether the internal combustion engine is not running. In the embodiment shown inFIG.4, the control unit42includes an ignition shutdown pin52connected to a shutdown switching element54. The shutdown switching element54is connected between the ignition coil of the ignition circuit48of the internal combustion engine and ground56. When the shutdown switching element54is in the closed condition, the ignition circuit48is connected directly to ground56which will ground the ignition coil. Grounding the ignition coil will either terminate operation of the internal combustion engine or will prevent starting of the internal combustion engine. When the shutdown switching element54transitions to the open condition shown inFIG.4, the ignition circuit48would be ungrounded and thus allow for operation or starting of the internal combustion engine. In the embodiment shown inFIG.4, the shutdown switching element54is a MOSFET switch that can transition between “open” and “closed” conditions through the application of a voltage to the MOSFET from the control unit42(e.g. via ignition shutdown pin52). Although a MOSFET is described in one embodiment as the shutdown switching element54, it should be understood that different types of switching elements, such as an SCR, transistor, IGBT or a relay, could be utilized while operating within the scope of the present disclosure. In one embodiment, the battery pack40includes an enable terminal58that is connected to an ignition switch19. The ignition switch19can be one of multiple different types, such as a multi-position key switch, a push button starter or any other type of device or switch that can generate an enable signal along line60. As an illustrative example, when the ignition switch19is a multi-position key switch, when the key switch is moved to a cranking position to start the engine, a signal is present along the line60, which in turn is received at the enable input pin62of the control unit42. The signal may be a digital low signal or a digital high signal, in certain configurations. Likewise, when the ignition switch19is a push button, depressing the push button creates a similar high signal along line60, which is also received at the enable input pin62. When the control unit42receives the enable signal at the enable input pin62, the control unit42can then determine whether starting of the internal combustion engine should be allowed to occur. For example, if the control unit42determines that the internal combustion engine is running, a starting action is not necessary, and could damage a starting motor64or the internal combustion engine itself. If the control unit42determines that the internal combustion engine is not running, based upon the signal present at the RPM input pin50, the control unit42can initiate operation of the starter motor64. To do so, the control unit42controls the operational state of a starter switching element66which is positioned between the series of battery cells34and the starter motor64. When the starter switching element66is in the closed condition, the voltage from the series of battery cells34is present at the 12-volt starter terminal68of the battery pack40. The 12-volt starter terminal68is connected directly to the starter motor64to provide the required twelve volts needed to operate the starter motor. In the embodiment shown inFIG.4, the starter switching element66is a MOSFET switching element, the condition of which can be controlled by the control unit through the voltage present at the starter control pin70. Although a MOSFET is described in one embodiment as the starter switching element66, it should be understood that different types of switching elements, such as an SCR, transistor, IGBT or a relay, could be utilized while operating within the scope of the present disclosure. In other configurations, the battery pack40may be configured to provide more than 12 volts or less than 12 volts to the starter terminal, as required by the specific starter motor. After the starter switching element66is in the “closed” condition, the battery voltage is supplied to the starter motor64through the starter terminal68. In one configuration, the control unit42monitors the signals from the ignition circuit48through the RPM input pin50to determine whether the internal combustion engine starts. In other configurations, the control unit42monitors a current of the starter motor to determine whether the internal combustion engine starts. For example, the starter pinion will get removed from the crankshaft once the internal combustion engine starts, resulting in reduced starter current draw. Once the control unit42determines that the internal combustion engine has started (e.g. via the signal received at the RPM input pin50), the control unit42transitions the starter switching element66to the “open” condition to disconnect the battery cells34from the starter motor64. In addition to providing voltage from the series of battery cells34to the starter motor64to initiate operation of the starter motor, the control unit42can control the condition of an auxiliary switching element72which is connected between the series of battery cells34and an auxiliary terminal74. The auxiliary terminal74provides power to a series of auxiliary devices and loads76of the lawn tractor though an auxiliary bus. These auxiliary loads can include lights, radio, a display, gauges or any other components on the vehicle that could be powered when the internal combustion engine of the tractor is not operating. As an illustrative example, if the operator of the lawn tractor wishes to operate the radio or lights of the tractor without turning the tractor on, the operator could move the key switch to an auxiliary position, which would be sensed by the control unit42at the enable input pin62. Since the internal combustion engine is not running (as determined by the control unit42based upon the signal present at the RPM input pin50), the control unit42may determine that the engine is not running and provide power to the auxiliary loads. Based upon these two inputs, the control unit42can then move the auxiliary switching element72to the “closed” condition and supply battery power to the auxiliary loads76for a limited period of time. In other embodiments, and as will be described in more detail below, the control unit42may include one or more additional enable inputs, such as an auxiliary enable which would allow the control unit42to receive a signal indicating that the key switch is placed into an auxiliary position or state, thereby instructing the control unit42to provide power to the auxiliary 12V system associated with the auxiliary devices and loads76described above. As can be understood by the above description, the inclusion of the ignition input terminal46on the battery pack40allows the control unit42to monitor the operation of the internal combustion engine. In such a manner, the control unit42is able to detect whether the internal combustion engine is running and allows the control unit42to disconnect the series of battery cells34from any auxiliary loads after the user has stopped operation of the internal combustion engine. This feature would prevent the battery pack40from draining the battery cells34if the ignition switch19is left in the on position. In addition, the control unit42will be able to ground the ignition circuit48of the internal combustion engine if desired. The inclusion of the ignition input terminal46on the battery pack40also allows the ignition switch19to provide additional functions when the ignition switch19is a push button. Specifically, when the internal combustion engine is running, the user can again depress the push button to stop operation of the internal combustion engine. When the control unit42is sensing operation of the engine through the RPM input pin50and then receives a high signal at the enable input pin62, the control unit42can stop the engine by grounding the ignition circuit48through the shutdown switching element54. As stated above, when the shutdown switching element54is in its “closed” condition, the ignition circuit48of the internal combustion engine is grounded, which stops operation of the internal combustion engine. Examples of use of this feature could be utilized in a pressure washer in which the internal combustion engine includes a spray wand having a trigger switch. When the trigger switch is initially pulled, the trigger switch will function in the same manner as a push button starting switch. Upon detecting the trigger switch, the microcontroller would start the internal combustion engine. When the trigger switch is released, the control unit42would sense such change of state and terminate operation of the internal combustion engine through the shutdown switching element54. In some embodiments, the control unit42may include a time delay circuit to prevent shutdown of the internal combustion engine immediately upon the user releasing the trigger switch. In one example, the time delay circuit may provide a ten second time delay. However, other time delay values are also contemplated. Other possible uses are also contemplated as being within the scope of the present disclosure. In some embodiments, the control unit42may be configured to provide additional functionality to the internal combustion engine and/or the outdoor power equipment in general. For example, the control unit42may be configured to provide motor control functionality to the internal combustion engine. Turning now toFIG.5, a schematic drawing illustrating the control unit42is shown, according to some embodiments. The control unit may include a microcontroller100. In some embodiments, the microcontroller100may have a number of input/output (I/O) connections connected to one or more components within the battery pack40. According to some embodiments, the I/O connections may include a battery positive (B+) start output102, a battery positive (B+) auxiliary output104, a battery negative (B−) ground output106, a temperature input108, an auxiliary power enable output110, and a start enable output112. The microcontroller100may further include a number of I/O lines for communicating with one or more other circuits. The I/O lines can include a communications bus114, a ground (or common) bus116, an auxiliary power output118, a daughter enable output120, and a start enable output122. In some embodiments, the start enable output122may be jumpered to the start enable output112. The control unit42may further include a daughterboard circuit124. In some embodiments, the daughterboard circuit124may be configured to operate as a multiplexor to allow for additional data to be provided to the microcontroller100via the daughterboard. In other embodiments, the daughterboard circuit124may include a microprocessor and/or a memory circuit for performing certain computations. The daughterboard circuit124may then provide the processed data to the microcontroller100. The daughterboard circuit124may also be referenced as an interface module. In one embodiment, the communication bus114may be configured as a serial data bus. For example, the communication bus114may be configured to operate using a CAN bus communication protocol, a K-line communication protocol, a universal serial bus (USB) communication protocol, and/or an RS-232 protocol. It is further contemplated that other communication protocols may be used to communicate between the microcontroller100and the daughterboard circuit124, including wired communication protocols, wireless communication protocols (RF, LoRa, Zigbee, Bluetooth, Bluetooth Low Energy, Wi-Fi, Cellular, etc.), or a combination thereof. In some embodiments, the communication bus114may provide bi-lateral (e.g. two way) communication between the microcontroller100and the daughterboard circuit124. In other embodiments, the communication bus114may provide unilateral (e.g. one way) communication from the daughterboard circuit124to the microcontroller100. The daughterboard circuit124may further include a number of I/O ports126for interfacing with one or more systems associated with an internal combustion engine. The I/o ports may be general purpose I/O ports (GPIO), pulse width modulation outputs, transistor output drivers (e.g. MOSFET drivers, BJT drivers, IGBT drivers, etc.), analog I/O, digital I/O, and the like. As shown inFIG.5, the I/O ports126may interface with a primary ignition circuit128, a Hall Effect power circuit130, a Hall Effect signal circuit132, an ignition kill circuit134, a positive coil terminal136, a negative coil terminal138, a flow/input switch circuit140, a ground connection142, and/or other engine/vehicle controls144. The ignition primary circuit128may communicate with the daughterboard circuit124via a bi-directional communication line and using an I/O port126of the daughterboard circuit124. For example, the ignition primary circuit128may communicate with the daughterboard circuit124via a GPIO port, an analog I/O port, or a digital I/O port, depending on the signal provide by the ignition primary circuit128. In one embodiment, the ignition primary circuit128receives a signal from the daughterboard to generate a spark, for use in initiating the combustion cycle within a cylinder of the internal combustion engine. Further, the ignition primary circuit128may provide a signal to the daughterboard circuit indicating when a spark has been generated (e.g. thereby initiating the combustion cycle) for one or more spark plugs in the system. This data may be used for ignition control, as will be described in more detail below. The hall effect power circuit130and the hall effect signal circuit132may be associated with a hall effect sensor located within the internal combustion engine. While the above embodiment is described as using a hall effect sensor, other sensor types, such as proximity switches, transducers, speed sensors, current sensors, time of flight (ToF) sensors, and the like may also be used. The hall effect power circuit130may provide power to the hall effect sensor. In one embodiment, the power may be supplied via the daughterboard circuit124. In other embodiments, the daughterboard circuit124may be in communication with a switch or power supply to provide an instruction to provide power to the hall effect sensor. The hall effect signal circuit132may provide data to the daughterboard circuit124from the hall effect sensor. In one embodiment, the hall effect signal circuit132provides a voltage indicating a distance of the hall effect sensor from a magnet producing a magnetic field. In one embodiment, a hall effect sensor may be placed near a portion of a crankshaft within the internal combustion engine. One or more magnetic elements may be coupled to the crankshaft. The hall effect sensor may then measure the distances to the one or more magnetic elements to determine a distance or position of the crank shaft. This information may be used to determine a crank angle of the engine, as will be described in more detail below. The ignition kill circuit134may be configured to deactivate one or more spark plugs on the internal combustion engine to stop ignition, and therefore stop the engine. In one embodiment, the ignition kill circuit134may include a switch to short the one or more spark plugs to ground. The switch may be configured to be controlled via a signal from the daughterboard circuit124. In other embodiments, the switch may be located within the daughterboard circuit124, thereby allowing the daughterboard circuit124to directly short the spark plugs to stop operation of the motor. In other embodiments, the daughterboard circuit124may control an enable circuit for the ignition circuit to allow the ignition to be enabled or disabled. The positive coil terminal136and the negative coil terminal138may be coupled to an electronic fuel injector (EFI) actuator for controlling the fuel injection into one or more cylinders of the internal combustion engine. While the embodiment shown inFIG.5illustrates only one set of coil connections, it is contemplated that multiple coil connections may be possible for controlling more than one EFI actuator. In the embodiment shown inFIG.5, the daughterboard circuit124may be configured to control the rate and timing of fuel injection into the engine, as will be described in more detail below. The flow/input switch circuit140may be coupled to a flow sensor for detecting a flow of a liquid associated with the internal combustion engine. In some embodiments, the internal combustion engine may be used to provide power to a cleaning device, such as a power washing device. The power washer may include a flow switch to detect a flow of water that occurs when a user actuates a flow valve (e.g. such as depressing a trigger on the power washing wand) which causes some water to flow through the power washer. The flow sensor may detect the flow of water through the actuated valve and or a portion of the power washer, and provide a signal to the daughterboard circuit124indicating that flow is detected. In some embodiments, this input may be communicated to the microcontroller100which can then initiate a starting procedure to start the internal combustion engine. The ground connection142may be connected to a ground of the internal combustion engine to provide a common ground. Finally, the other engine/vehicle controls144may include connections to various systems or components of the engine or vehicle, such as sensors, attachment controls, speed controls, safety components, etc. While the embodiment ofFIG.5shows the above described circuits and connections, it is contemplated that the daughterboard may be configured to include more or fewer I/O ports for communicating with various systems associated with an internal combustion engine. Turning now toFIG.6, a block diagram showing one configuration of the control unit42is shown. The control unit42includes the microcontroller100, as described above. The control unit further includes the daughterboard circuit124, as described above. The control unit42includes a processing circuit200. The processing circuit is shown to include a processor202and a memory204. The processor202may be general purpose or specific purpose processor, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGAs), a group of processing components (e.g. parallel processing units), a neural network processing system, or other applicable processing circuits. The processor202may be configured to execute computer code or instructions stored in memory202or received from other computer readable media, such as physical media (e.g. CD-ROM, DVD-ROM, flash drive, etc.), network drives, remote servers, mobile devices, etc. The memory204may include one or more devices (e.g. memory units, memory devices, storage devices, etc.) for storing data and/or computer code for completing and/or facilitating the functions and processes described in the present disclosure. The memory204may include random access memory (RAM), read-only memory (ROM) hard drive storage (physical or solid state), temporary storage, non-volatile memory, flash memory, optical memory, or any other suitable memory component for storing software objects and/or computer instructions. The memory204may include database components, object code components, script components, or any other type of information structure for supporting the various functions and information structures described in the present disclosure. The memory204may be communicably connected to the processor via the processing circuit and may include computer code for executing (e.g. by the processor) one or more processes described herein. The microcontroller100may further be in communication with a user interface206associated with an internal combustion engine208and/or a piece of outdoor power equipment associated with the internal combustion engine208. The control unit42may further include a communication interface210and an I/O interface212. The I/O interface may include the I/O102-112described above in the embodiments described in relation toFIG.5. The memory204may include a number of modules configured to include multiple modules to perform various functions associated with the internal combustion engine208and/or outdoor power equipment associated with the internal combustion engine208. As shown inFIG.6, the memory204includes an electronic fuel management (EFI)/automatic choke module214, an electronic governor (e-gov) module216, a display interface218, a pushbutton start/stop control module220, an ignition control module222, a crank angle determination module224, an electronic fuel injection (EFI) module226, an internet of things (IoT) module228, and an other engine/vehicle controls module229. The EFM module214may be configured to operate a choke function on a carbureted internal combustion engine. In one embodiment, the EFM module214may be configured to control one or more electric motors associated with controlling a choke plate of a carburetor. In one embodiment, the EFM module214may interface with one or more I/O ports230on the daughterboard circuit124to control the electric motors associated with controlling the choke plate. For example, the I/O ports230of the daughterboard circuit124may include one or more switched outputs (e.g. MOSFET switched outputs) for controlling a power and direction of power provided to the one or more electric motors associated with controlling the choke plate of the internal combustion engine. The daughterboard circuit124may further include one or more inputs to receive an input related to the EFM control of the internal combustion engine208. For example, the daughterboard circuit124may include an analog input for receiving an analog temperature input which can be used to control the choking of the engine. For example, as the engine temperature increases, the choke plate may be opened further to allow additional air into the carburetor, thereby reducing the suction pressure within the carburetor. Other inputs may include an engine speed input, a user controlled throttle input, an engine run timer, an engine cycle counter, etc. These inputs can be communicated to the EFM module214via a serial communication port232on the communication interface210to allow the EFM module to determine a required position of the choke plate. The serial communication port232may utilize multiple serial communication protocols and/or hardware, including universal asynchronous receiver-transmitter (UART) communication, a serial peripheral interface bus (SPI), including MOSI, MISO, SCK, CS, and I2C, serial data lines (SDA), serial clock lines (SCL), universal serial bus (USB), RS-232, k-line, CAN, and the like. The EFM module214may use the inputs as feedback to accurately control the flow of air into a carburetor. The e-gov module216may be configured to control one or more electric motors associated with a throttle plate within a carbureted internal combustion engine. The electric motors may be configured to move the throttle plate to control the air-fuel mixture provided to the internal combustion engine cylinders. In some embodiments, the electric motors may be stepper motors. In other embodiments, the electric motors may be coupled to a geared system for controlling the position of the throttle plate. In some embodiments, the geared system may be configured such that the gearing ratio is sufficiently high to maintain the position of the throttle plate without requiring the electric motor to provide torque to maintain the position. This concept is described in U.S. patent application Ser. No. 14/702,435, titled “Electronic Governor System and Load Sensing System” and filed May 1, 2015, the contents of which are herein incorporated by reference in their entirety. In one embodiment, the e-gov module216may interface with one or more I/O ports230on the daughterboard circuit124to control the electric motors associated with controlling the throttle plate. For example, the I/O ports230of the daughterboard circuit124may include one or more switched outputs (e.g. MOSFET switched outputs) for controlling a power and direction of power provided to the one or more electric motors associated with controlling the throttle plate of the internal combustion engine. The switched outputs may be configured as pulse width modulated (PWM) outputs. The daughterboard circuit124may further include one or more inputs to receive an input related to the e-gov control of the internal combustion engine208. For example, the daughterboard circuit124may include an analog input for receiving an engine speed which can be used to control the throttle. For example, as the engine speed increases, the throttle plate may be positioned to reduce the air-fuel mixture provided to the internal combustion engine to maintain a speed of the engine. The daughterboard circuit124may further include a number of GPIO for other inputs and/or outputs associated with e-governor control. These can include throttle position sensors, user throttle controls, etc. The EFM module214may communicate with the daughterboard circuit124, and thereby the various components of the e-gov system, via the serial communication port232on the communication interface210. In some embodiments, the e-gov module216may use the inputs as feedback to accurately control the fuel-air mix provided to the internal combustion engine208. The display interface module218may be configured to interface with the user interface206associated with the control unit42. In some embodiments, the user interface may be integrated into a battery housing, such as a display for providing battery related data to the user. In other embodiments, the user interface206may be configured to provide various data to a user related to the battery, as well as the internal combustion engine. For example, the display interface module218may provide engine parameters to the user interface206, such as RPM, engine temperature, fuel level, throttle level, etc. While shown as coupled to the control unit42, the user interface206may be remote from the control unit. For example, the user interface206may be coupled to a portion of the outdoor power equipment, such as an operator control station, on a pushbar assembly, or other location on the outdoor power equipment that allows for an operator to easily access the information provided by the user interface206. In some embodiments, the control unit42can communicate to the user interface206via the serial port232. The pushbutton start/stop control module220may be configured to interface with a starter motor of the internal combustion engine. For example, the pushbutton start/stop control module220may interface with the start enable I/O112, the B+ start output102and the B− ground output106to control the starter motor. For example, the pushbutton start/stop control module220may receive an indication that a user wishes to start the internal combustion engine208, such as when the user actuates a switch or button associated with the start enable I/O. As a further example, the pushbutton start/stop control module220may interface with the B+ start output102, the B+ auxiliary output104, the B− ground output106, the temperature input108, the auxiliary power enable output110, and the start enable I/O112. In one embodiment, the I/O, such as the start enable I/O112, the B+ start output102, and the B− ground output106may be part of the microcontroller100I/O212. However, in some embodiments, the above I/O may be associated with the I/O230of the daughterboard circuit124. Furthermore, in other embodiments, the I/O may be a combination of the microcontroller I/O212and the daughterboard circuit I/O230. In one embodiment, the pushbutton start/stop control module220may control a GPIO for communication with the start/stop input (e.g. start enable112), as well as a switched output (e.g. a MOSFET switch) which can be used to control power to the starter motor. In one embodiment, the switched output is a low side switch for switching the ground connection to the coil of the starter motor (e.g. B− ground), to allow current to flow from the battery and through the starter motor. However, in other embodiments, the switched output may be a high side switch to control the application of voltage from the battery to the starter motor. In some embodiments, the pushbutton start/stop control module220may also control a switch connected to the ignition system, such as the ignition kill circuit134to allow for the pushbutton start/stop control module220to kill the ignition when receiving an input from the user indicating a desire to stop operation of the internal combustion engine208. For example, the pushbutton start/stop control module220may communicate with the daughterboard circuit124via the serial communication port232. The daughterboard circuit124may then activate the ignition kill circuit134to stop combustion, and thereby stop operation of the internal combustion engine208. The ignition control module222may be configured to control ignition associated with the internal combustion engine208. For example, the ignition control module222may control the firing of one or more spark plugs within the internal combustion engine208. In one embodiment, the ignition control module222may be configured to enable the one or more spark plugs to spark, thereby providing ignition. This can allow the ignition control module222to control when ignition is occurring within the internal combustion engine208. In some embodiments, the ignition control module222interfaces with the ignition system via the microcontroller I/O212. In other embodiments, the ignition control module222may interface with the ignition system via the daughterboard circuit I/O230. For example, the ignition control module222may interface with the ignition primary circuit128and/or the ignition kill circuit134, as described above. The crank angle module224may be configured to time the firing of the one or more spark plugs within the internal combustion engine208based on one or more operating conditions. For example, the internal combustion engine208may typically fire the spark plugs at 24° before top dead center during normal operation. However, it may be advantageous to fire the spark plugs at a smaller angle (such as 4° before top dead center) during certain operating conditions, such as starting. It is understood that the above crank angles are for illustrative purposes and it is contemplated that multiple crank angles are contemplated as applicable to different operating conditions present on the internal combustion engine208. In some embodiments, the crank angle module224may determine a cranking position based on the position of a crank shaft within the internal combustion engine. The position of the crank shaft may be determined by the crank angle module224based on data provided by the daughterboard circuit124. For example, the daughterboard circuit124may receive position data via the hall effect signal circuit132. The hall effect sensor associated with the hall effect signal circuit132may provide position data regarding the crank shaft, which may then be transmitted to the daughterboard circuit124for communication to the crank angle module224. While the above description illustrates the use of a hall effect sensor to determine the position of the crank shaft, other sensors and methods of determining the position of the crank shaft are also contemplated, such as those described above. The EFI module226may be configured to control one or more fuel injectors associated with a fuel injection system of the internal combustion engine208. In some embodiments, the EFI module226may be in communication with a throttle control of the internal combustion engine to increase or decrease the volume and/or frequency of fuel provided to each cylinder during operation. In some embodiments, the EFI module226may be in communication with other modules, such as the ignition control module222and/or the crank angle module224to determine when to actuate the one or more fuel injectors. In some embodiments, the EFI module226may communicate with the coils of the fuel injectors via the coil circuits136and138by communicating with the daughterboard. In some embodiments, the EFI module226may be integrated into the daughterboard230and communicate directly to the fuel injectors via the coil circuits136and138. The Internet-of-Things (IoT) module228module may be configured to interface with one or more remote devices via a wireless communication port234. In one embodiment, the wireless communication port234may be integrated into the control module100, or as part of the control unit42. In some embodiments, the wireless interface may be integrated into the daughterboard230to allow for wireless communication to be added to the control unit42. In some embodiments, the wireless communication module234may be configured to communicate using one or more wireless protocols. For example, the wireless communication module234may utilize wireless protocols including Wi-Fi (e.g. 802.11x), Wi-Max, cellular (e.g. 3G, 4G, LTE, CDMA, etc.), LoRa, Zigbee, Zigbee Pro, Bluetooth, Bluetooth Low Energy (BLE), Near Field Communication (NFC), Z-Wave, 6LoWPAN, Thread, RFID, and other applicable wireless protocols. In some embodiments, the wireless communication module234may be in communication with a cloud-based server236. The cloud-based server236may be configured to interface with multiple programs and interfaces, and be accessible via the world wide web (e.g. the Internet). This can allow a user to access the control unit42via any device that has access to the world wide web. For example, a user may be able to access the control unit42via a mobile device such as an internet connected computer, a smartphone (e.g. iPhone, Android phone, Windows phone), a tablet computer (e.g. iPad, Android Table, Microsoft Surface, etc.), or any other internet connected device. In some embodiments, the cloud-based server236may provide one or more web-based applications for interfacing between a user device and the control unit42, and thereby the associated outdoor power equipment. In other embodiments, the user's device may include a client-side application, which can interface with the control unit42via the cloud-server236. In still further embodiments, the user's device may include one or more client-side applications which can be configured to communicate directly to the control unit via the wireless communication interface234, such as via Bluetooth, BLE, NFC, Zigbee, etc. The other engine/vehicle controls module229may be configured to interface with other systems or components associated with the internal combustion engine208and/or an associated vehicle or equipment. In some embodiments, the other engine/vehicle controls module229may communicate with the other systems or components via the I/O module212. For example, the other engine/vehicle controls module229may be configured to control various functions of the internal combustion engine208and/or the associated vehicle or equipment, including speed controls, implement (e.g. blades, blowers, etc.) control, suspension control, speed control, attachment control, lighting systems, comfort systems (e.g. heat, charging circuits, radios, etc.), and other applicable systems, as needed. In some embodiments, the other engine/vehicle controls module229is configurable to allow for controls to be implemented based on the configuration of the internal combustion engine208, and/or the vehicle or equipment. In some embodiments, the other engine/vehicle controls module229may be configured to determine the type of internal combustion engine208and/or vehicle or equipment it is coupled to based on a user setting via the user interface206. In other embodiments, the other engine/vehicle controls module229may be configured to determine the type of internal combustion engine208and/or vehicle or equipment it is coupled to based on the presence of one or more I/O points. In still further embodiments, the other engine/vehicle controls module229may be configured to determine the type of internal combustion engine208and/or vehicle or equipment it is coupled to based on a communication received via the communication interface210. The other engine/vehicle controls module229may then execute one or more functions based on determining the type of internal combustion engine208and/or vehicle or equipment it is coupled to. The IoT module228may include one or more software applications configured to process data or instructions received via the wireless communication module234. In some embodiments, the IoT module may process data provided by one of the above described software modules214-226, and provide that data to a user device or to the cloud-based server236via the wireless communication interface234. While the IoT module228is shown as integrated into the microcontroller100, it is contemplated that the IoT module228may integrated into the daughterboard circuit230in some embodiments, and communicate with the microcontroller100via the communication interface210. As discussed above, the communication interface module210can provide an interface between components such as the daughterboard circuit124and the microcontroller. In some embodiments, the communication module210may communicate via the serial interface232to the daughterboard circuit124and/or the microcontroller200using one or more serial communication protocols, such as those described above. As stated above, in some embodiments, the control modules214-228may be integrated into the microcontroller. In other embodiments, some or all of the control modules214-228may be integrated into the daughterboard circuit230, which may also include a processing circuit similar to the processing circuit202described above. Further, it is contemplated that more or fewer control modules may be used for a given application. Additional control modules may include GPS modules, compass modules, microelectromechanical systems (MEMS) modules, traction control modules, autonomous operation modules, and the like. Turning now toFIG.7, a perspective view of the internals of battery pack40. As shown inFIG.7, a daughterboard circuit700is shown attached at a proximal end of the battery pack. In one embodiment, the daughterboard circuit700is similar to the daughterboard circuit124as described above. The daughterboard circuit700is shown to include a battery interface702and an engine interface704. In some embodiments, the daughterboard circuit700may be mechanically coupled to the battery pack40during manufacturing of the battery pack40. In other embodiments, the daughterboard700may be coupled to the internals of the battery pack40after manufacturing during a final assembly process (e.g. by an OEM). In still further embodiments, the daughterboard circuit700may be configured to include a microcontroller (such as microcontroller100described above) and to further integrate the BMS of the battery pack40into a single circuit board/module. The engine interface704may be the same as the I/O126described above, and be configured to access various systems and components associated with the engine. The engine interface704may include a connector or other coupling device to provide an interface between the battery pack40and the engine. For example, a user may be able to plug a wiring harness into the engine interface704. In other embodiments, the engine interface may couple to one or more connection points on the out housing22of the battery pack40. A receptacle for the battery pack40may include corresponding connection points for interfacing with the one or more systems/components within the engine for communication with the daughterboard circuit. The battery interface702may be configured to interface with a microcontroller or battery management system controller associated with the battery pack40, as described above. The battery interface702may include a coupling device to allow for a connector cable to be connected between the battery interface702and the microcontroller100of the battery pack40. In other embodiments, the battery interface702may include a connector for coupling directly to a circuit board associated with the microcontroller100/BMS of the battery pack40. Turning now toFIG.8, a perspective view of the battery housing22is shown, according to some embodiments. The battery housing22shows multiple potential locations for an externally mounted daughterboard circuit800. The externally mounted daughterboard800shown inFIG.8may be the same as daughterboard124described above. In some embodiments, the daughterboard circuit800may have a housing which may be configured to couple to one or more external faces of the battery housing22. Further, the daughterboard800may have an engine interface and a battery interface as described above inFIG.7. As shown inFIG.8, the daughterboard800may be configured to mount to any face of the battery housing22. In some embodiments, the daughterboard800may be configured to mount to the bottom of the battery housing and can be configured as an interface between the battery housing22and a battery receptacle on the engine. This can allow for the daughterboard circuit to interface with one or more contacts within the battery receptacle which may be in electronic communication with one or more systems or components within the engine or outdoor power equipment, as described above. Further, the daughterboard800may contain a battery interface, as described above which can communicate between the daughterboard800and the microcontroller/BMS of the battery pack40, as well as passing the signals and power from the battery pack40, through the daughterboard circuit800, and to the engine, and vice versa. This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. | 49,579 |
11859591 | DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS FIGS.1,2of the attached drawings show schematic views of an embodiment example of the engine described in the Applicant's European patent EP 3 453 856 B1. Of course, this engine is described here as an example of an engine to which the present invention is applicable. However, as already indicated, the method of the invention is generally applicable to any engine with two spark plugs per cylinder. FIG.1is a schematic cross-sectional view of the engine, in a sectional plane showing the combustion pre-chamber with the first spark plug (which in the example is centrally located on the cylinder axis), and the main combustion chamber with the second spark plug (which in the example is lateral to the cylinder axis). FIG.2is a further cross-sectional view of the engine ofFIG.1in a sectional plane showing the combustion pre-chamber with the associated spark plug, the intake duct and the exhaust duct associated with the cylinder, and respective gasoline injectors, one associated with an intake duct and the other directly associated with the main combustion chamber. In accordance with the conventional technique, the engine illustrated inFIGS.1,2comprises a crankcase1defining a plurality of cylinders2(one of which is illustrated in the drawings). Of course, the engine configuration described below with reference to a cylinder is repeated on each of the other cylinders of the engine. Still in accordance with the conventional technique, a cylinder head3is mounted on the crankcase1, in which, at each cylinder2the following are formed: a combustion chamber4, at least one intake duct5, and at least one exhaust duct6, with which respective intake and discharge valves7,8are associated (seeFIG.2). Conventionally, within each cylinder2, a piston9is movable, produced according to any known configuration, connected by a piston rod10(shown only partially in the drawings) to a respective crank of the engine crankshaft (not shown). Still with reference toFIGS.1,2, for each cylinder2, a first spark plug11is provided, mounted within a support element12defining a combustion pre-chamber13inside it. The support element12is configured to be mounted within a seat of the engine head3, which leads into the combustion chamber4. The support element12has a relatively elongated configuration, with one end carrying the spark plug11and the opposite end facing the combustion chamber4and having a plurality of orifices14for communication of the combustion pre-chamber13with the combustion chamber4. As visible inFIGS.1,2, in the example shown here, the combustion pre-chamber is centrally arranged with respect to the main combustion chamber4, and has its main axis parallel to the axis of the respective cylinder. However, different positions and orientations of the pre-chamber13with respect to the cylinder2are not excluded. One side of the combustion chamber4is provided with a second spark plug15, with electrodes15A directly facing the combustion chamber4. The engine described here can be designed for producing a direct injection of gasoline into the combustion chamber4, by means of an electromagnetically-controlled injector16directly associated with the combustion chamber4, or to produce an indirect injection of gasoline, by means of an electromagnetically-controlled injector17, associated with the intake duct5, or to produce a mixed direct and indirect injection, by providing both injector devices16,17. The injector devices16and17, the first spark plug11and the second spark plug15arranged for each cylinder of the engine are controlled by an electronic control unit (not illustrated). As is apparent from the foregoing description, the engine combustion pre-chamber of the invention is of a “passive” type in that it is not associated with any device for injecting fuel or air, or a mixture of air and fuel, directly into the combustion pre-chamber13. During operation, the combustion pre-chamber fills with the load of the cylinder that enters the combustion pre-chamber passing through the orifices14, driven by the piston9during the compression step of the load in the cylinder. In the case of the solution forming the subject of EP 3 453 856 B1, the electronic control unit is programmed to control the injector device16and/or the injector device17in order to produce an air/gasoline mixture in the combustion chamber according to a ratio essentially corresponding to a stoichiometric dose, or a richer dose than the stoichiometric dose. The electronic control unit is also programmed in such a way that the second ignition spark plug, having electrodes directly facing the combustion chamber, is only activated at low and medium engine loads to stabilize the combustion, and is inactive or kept active but without any influence on the combustion, for example, by activating it during the expansion or discharge step of the cylinder, at higher loads, As already indicated above, the present invention has been developed in particular with reference to the engine described above, but is in any case applicable in general to any gasoline internal combustion engine having two spark plugs for each cylinder. The problem that arises in engines of this type is that of controlling the ignition of the two spark plugs of each cylinder of the engine so as to obtain maximum engine efficiency in any engine operating condition. FIG.3shows a block diagram of an example of a method for controlling the ignition, which can be implemented in the electronic controller of a gasoline internal combustion engine of the conventional type, having a single spark plug for each cylinder. In an engine of this type, the electronic control unit of the engine is capable of commanding, for each cylinder, in each cylinder operating cycle, the ignition of the single spark plug with which the cylinder is equipped at a determined crank angle, as a function of the operating point of the engine (that is, of the values of the engine load and of the rotation speed of the engine) and as a function of a required value of the torque delivered by the engine. The torque (Torque) delivered by the engine is closely linked to the value of the gross mean effective pressure (IMEPh) obtained at each cycle inside the cylinder. The efficiency (n) of the engine, understood as the ratio between the torque (“Torque”) delivered by the engine and the optimal torque (“Torque opt”) delivered by the engine is equal to the ratio between the IMEPh in the cylinder and the maximum value IMEPh opt which can be obtained in the cylinder: η=IMEPh/IMEPh opt (1) If SA is the engine crank angle at which the ignition of the single spark plug of each cylinder is commanded and SAopt is the engine crank angle of ignition of the spark plug that gives rise to the optimal value IMEPh opt in the cylinder, it follows that the efficiency of the engine is a function of the difference between the optimum ignition angle and the effective ignition angle: η=f(SAopt−SA) (2) FIG.3is a flowchart showing the operations with which, in a gasoline internal combustion engine with a single spark plug per cylinder, the control unit can determine the value of the torque delivered by the engine as a function of the operating point of the engine, and as a function of the value of the engine crank angle which causes the ignition of the spark plug. InFIG.3, in block100reference maps are used, obtained empirically for a given engine, to supply an output signal111indicative of the optimal torque (Torque opt) which can be delivered by the engine as a function of signals101and102entering the block100, respectively indicative of the engine load and engine rotation speed values. Each pair of engine load and engine speed values represents an engine operating point. The block100makes use of different reference maps for different engine operating points. Again inFIG.3, the block103makes use of reference maps, obtained empirically for a certain type of engine, to supply an output signal105indicative of the optimum engine crank angle for spark plug ignition (“SA opt”) as a function of signals101,102entering the block103, which supply information on the engine load and engine rotation speed. The block104receives the signal105containing the information relating to the value “SA opt” supplied by the block103, and a signal106which supplies information on the current value of the engine crank angle “SA” which causes ignition of the spark plug. The block104outputs a signal107that supplies information on the difference Delta SA between the current engine crank angle of ignition of the spark plug and the optimum engine crank angle for ignition of the spark plug. The signal107containing the information on the Delta SA value is sent to a block108, in which a single normalized curve F is used (illustrated inFIG.4), which supplies the engine efficiency as a function of the Delta SA value. The curve F is a normalized curve which is always the same whatever the operating point of the engine. A block110receives at its input both the signal111indicative of the optimal torque (Torque opt) which can be delivered by the engine, and the signal109indicative of the efficiency of the engine, and emits an output signal112indicative of the effective torque delivered by the engine for the operating point considered (engine load and engine speed) and for the current value of the engine crank angle at which the spark plug is ignited. Therefore, the engine control in the case of an engine having a single spark plug per cylinder is relatively simple, thanks to the fact that it is possible to refer to a single normalized curve F (FIG.4), which gives the efficiency of the engine operating the Delta SA difference between the optimum engine crank angle for spark plug ignition and the actual engine crank angle at which the spark plug ignites. In the case of a gasoline internal combustion engine having two spark plugs per cylinder, which can be controlled independently, the problem arises of identifying a simple and reliable way to control the engine crank angle of ignition of the first spark plug associated with the combustion pre-chamber (spark plug11inFIG.1) and the engine crank angle of ignition of the second spark plug whose electrodes directly face the combustion chamber (spark plug15inFIG.1) in order to obtain a required torque from the engine in any engine operating condition. In the method according to the invention the engine crank angle SA1of ignition of the first spark plug and the engine crank angle SA2of ignition of the second spark plug are determined on the basis of the operations described below. With reference toFIG.5of the attached drawings, a first operation consists in detecting empirically, for a given engine, a plurality of three-dimensional reference surfaces C1, C2, . . . , Cn in a diagram with three orthogonal axes x, y, z, wherein each three-dimensional reference surface C1, C2, . . . , Cn corresponds to a respective engine operating point, i.e. to a determined pair of values of the engine rotation speed and engine load, and wherein each of the aforesaid three-dimensional reference surfaces C1, C2, . . . , Cn supplies on the z axis an IMEPh value (measured in bar) of the gross indicated mean effective pressure established at each cycle inside the cylinder, according to the value shown on the x axis of the engine crank angle SA1of ignition of the first spark plug (measured in degrees BTDC, i.e. in degrees before the Top Dead Center of the piston in the cylinder) and the value reported on the y axis of the engine crank angle SA2of ignition of the second spark plug (also measured in degrees BTDC, i.e. in degrees before Top Dead Center of the piston in the cylinder). As an alternative to the above, instead of the aforesaid IMEPh parameter, it is possible to refer to another equivalent parameter, such as, for example, the work generated in the step of the operating cycle in the cylinder which goes from the end of the intake step to the beginning of the discharge step. With reference toFIG.6, a further operation envisaged in the method according to the invention consists of empirically determining, for the aforesaid engine operating points, and as a function of the engine crank angle SA1at which the first spark plug is ignited and the engine crank angle SA2at which the second spark plug is ignited, the value MFB50of the engine crank angle at which 50% of the mass of fuel is burnt. On the basis of the aforesaid empirical findings, for each of the aforesaid engine operating points, corresponding to a pair of values of the engine rotation speed and engine load, it is possible to define a respective curve IMEPh/MFB50(inFIG.6these curves are indicated by L1, L2, . . . , Ln) which supplies the value IMEPh of the gross indicated mean effective pressure as a function of the value MFB50of the engine crank angle at which 50% of the fuel mass is burnt. With reference toFIG.6, the values of MFB50on the x-axis are measured in degrees ATDC, i.e. in degrees after Top Dead Center, while the ordinate values of the indicated gross mean effective pressure IMEPh are expressed in bar. On the basis of the diagram ofFIG.6, which is obtained empirically for a given engine, the method of the invention includes the operation of calculating, for each point of an IMEPh/MFB50curve corresponding to a given operating point of the engine, the ratio between the value of IMEPh at that point and a maximum value (IMEPh opt) of IMEPh along said curve. Maximum value of the curve means the maximum value corresponding to a maximum point of the curve (as in the case of the curve Ln inFIG.6) or to a maximum point corresponding to an extension of the curve obtained by extrapolation (as in the case of the curves L1, L2ofFIG.6). In the method according to the invention, the aforesaid ratio between the value of IMEPh at a given point of a curve in the diagram ofFIG.6and the corresponding maximum value IMEPh opt is taken as representative of the engine efficiency, since it substantially corresponds to the ratio between the torque delivered by the engine and the optimum torque that would be delivered for the aforesaid maximum value IMEPh opt of the gross indicated mean effective pressure. On the basis of the aforesaid calculation, the method according to the invention, therefore, includes the transformation of the aforesaid three-dimensional reference surfaces C1, C2, . . . , Cn illustrated in the diagram ofFIG.5in transformed three-dimensional surfaces T1, T2, . . . , Tn (seeFIG.7), which in a diagram with x, y, z axes, supply on the z axis the value of the efficiency of the engine as a function of the values SA1of the engine crank angle of ignition of the first spark plug plotted on the x-axis, and of the values SA2of the engine crank angle of ignition of the second spark plug plotted on the y-axis. At this point, the method according to the invention envisages the operation of translating each of the aforesaid transformed three-dimensional surfaces T1, T2, . . . , Tn, parallel to the x axis and to they axis (seeFIG.8) by assigning:to the x-axis the values of the differential (Delta SA1) between an optimum value (SA1opt) of the ignition crank angle of the first spark plug for which the efficiency is unitary and the value SA2of the ignition crank angle of the first spark plug, andto the y-axis the values of the differential (Delta SA2) between an optimum value (SA2opt) of the engine crank angle of ignition of the second spark plug for which said efficiency is unitary and the value SA2of the engine crank angle of ignition of the second spark plug, in such a way as to obtain transformed and translated three-dimensional surfaces globally indicated with the reference G inFIG.8. The surfaces globally indicated with G inFIG.8are approximated with a single normalized reference surface G (see alsoFIG.9), which can be taken as a single reference, for any operating point of the engine, to determine the relationship between the torque delivered from the engine and the values SA1and SA2of the ignition crank angle of the first spark plug and of the ignition crank angle of the second spark plug. InFIG.9, the single normalized reference surface G supplies the efficiency value of the engine (the maximum efficiency is 1) as a function of the Delta SA1and Delta SA2values expressed in degrees. With reference toFIG.10, in the block200, for a determined engine operating point, i.e. as a function of signals201,202containing information on the rotation speed of the engine and on the engine load, the optimum torque (Torque opt) that the engine can deliver is determined, starting from given values SA1and SA2of the engine crank angle of ignition of the first spark plug and of the engine crank angle of ignition of the second spark plug, on the basis of the IMEPh/MFB50curve corresponding to the engine operating point considered, referring to a maximum value (IMEPh opt) assumed by IMEPh along said curve, where this maximum value corresponds to a maximum point of the curve or a maximum point defined by an extension of the curve obtained by extrapolation. The signal203leaving the block200and containing the information on the optimal torque (Torque opt) is sent to a block204for calculating the torque delivered by the engine. Again with reference toFIG.10, in the blocks205and206, as a function of the signals201,202containing the information on the engine rotation speed and on the engine load, the optimal values SA1opt and SA2opt are determined of the engine crank angle of ignition of the first spark plug and of the engine crank angle of ignition of the second spark plug, for which the IMEPh value given by the aforesaid IMEPh/MFB50curve is a maximum value, where maximum value means the value corresponding to a maximum point of the aforesaid curve or to a maximum point defined by an extension of the curve obtained by extrapolation. The signal207leaving from the block205, containing the information on the optimal value SA1opt, is sent to a block208which also receives a signal209containing the information on the current engine crank angle of ignition of the first spark plug. The signal210leaving from the block206, containing the information on the optimal value SA2opt, is sent to a block211, which also receives a signal217containing information on the current engine crank angle of ignition of the second spark plug. Signals212,213leave from the blocks208,211, indicative of the differential values SA1opt−SA1(Delta SA1) and SA2opt−SA2(Delta SA2). Again, with reference toFIG.10, in the block214, on the basis of the aforesaid single normalized surface G (FIG.9), an efficiency value of the engine is determined as a function of the calculated values Delta SA1and Delta SA2. The signal215leaving the block214and containing the information on the efficiency of the engine in the conditions considered, is sent to the block204, which, on the basis of the signal215indicative of the efficiency of the engine and of the signal203indicative of the optimal torque (Torque opt), is consequently capable of outputting a signal216containing information on the effective torque delivered by the engine. FIG.11illustrates the projection onto the xy plane of the normalized reference surface G. In the xy plane illustrated inFIG.11, the zero value of Delta SA1and the zero value of Delta SA2correspond to the condition wherein the engine crank angle of ignition of the first spark plug and the engine crank angle of ignition of the second spark plug are the optimal values, at which the engine efficiency has value 1. In the diagram ofFIG.11, it is therefore possible to identify lines, such as for example the line q, the points of which correspond to the same value of the engine efficiency. In other words, a variation of the Delta SA1and Delta SA2values, which corresponds to a point always situated on the line q always gives rise to the same efficiency value of the engine. During engine operation, the diagram ofFIG.11is taken as a base reference to determine how to vary the engine crank angle of ignition of the first spark plug and the engine crank angle of ignition of the second spark plug, in order to reach a point in the diagram with an efficiency value corresponding to a given target value of the torque delivered by the engine. Assuming, for example, that the starting condition of the engine corresponds to the point indicated with A inFIG.11, the Delta SA1and Delta SA2values are varied by the electronic controller of the engine in order to travel the predetermined path indicated by m inFIG.11, which starting from point A, first reaches a point B (through a variation of Delta SA1, without variation of Delta SA2) and then from point B to a target point C moving on a straight line, which in this example is inclined at 45° with respect to the x, y axes of the diagram (which corresponds to varying Delta SA1in an identical way to varying Delta SA2). The predetermined path m is chosen on the basis of empirical data in such a way as to favor combustion stability and consequently reduce the cyclic dispersion of the torque delivered by the engine. FIGS.12,13illustrate two further examples of predetermined paths to be followed in the projection on the xy plane of the normalized reference surface G. Each trajectory starts from a point A, passes through a point B and arrives at a point C. In the case ofFIG.12, the first section AB is covered by keeping the Delta SA2value constant, and varying only the Delta SA1value, after which a straight line inclined at 45° is followed, in a similar way to what has been illustrated inFIG.11. In the case ofFIG.13, point1is the start, in a condition wherein only the first spark plug is ignited. In this condition, the Delta SA1value is varied until it reaches point B, after which the curved path BC is followed by also triggering the second spark plug and varying both the Delta SA1and Delta SA2values. From point C to the final point D, a straight line is followed, varying both the Delta SA1and Delta SA2values until reaching a point with an engine efficiency corresponding to the target value of the torque delivered. As is evident from the preceding description, the method according to the invention makes it possible to manage spark plug ignition control in a gasoline internal combustion engine wherein each cylinder is equipped with two spark plugs, in any case referring to a single normalized surface (surface G ofFIG.9), usable for any operating point of the engine, which gives the advantage of simplifying the control of the engine, while still guaranteeing the reliability and robustness of the control method. Of course, without prejudice to the principle of the invention, the details of construction of the engine and the embodiments of the method may vary widely with respect to those described and illustrated purely by way of example, without departing from the scope of the present invention, as defined by the attached claims. | 23,077 |
11859592 | In the Figures, like reference numerals designate like or functionally equivalent elements, unless otherwise indicated. DETAILED DESCRIPTION FIG.1shows a wind turbine1according to one embodiment. The wind turbine1comprises a rotor2connected to a generator (not shown) arranged inside a nacelle3. The nacelle3is arranged at the upper end of a tower4of the wind turbine1. The tower4has a plurality of tower sections that are arranged on top of each other. The tower4can be named wind turbine tower. The rotor2comprises three rotor blades5. The rotor blades5are connected to a hub6of the wind turbine1. Rotors2of this kind may have diameters ranging from, for example, 30 to 160 meters or even more. The rotor blades5are subjected to high wind loads. At the same time, the rotor blades5need to be lightweight. For these reasons, rotor blades5in modern wind turbines1are manufactured from fiber-reinforced composite materials. Therein, glass fibers are generally desired over carbon fibers for cost reasons. Oftentimes, glass fibers in the form of unidirectional fiber mats are used. FIG.2shows a rotor blade5according to one embodiment. The rotor blade5comprises an aerodynamically designed portion7, which is shaped for optimum exploitation of the wind energy and a blade root8for connecting the rotor blade5to the hub6. FIG.3shows again the wind turbine1according toFIG.1. As mentioned before, the tower4has a plurality of tower sections9to13that are arranged on top of each other. The number of tower sections9to13is arbitrary. The tower4has a lowest tower section9and a topmost tower section13. The nacelle3can be attached to the topmost tower section13. The wind turbine1has a foundation14that can be anchored in the seabed. Between the foundation14and the lowest tower section9is arranged a transition piece15. The transition piece15is a circular or tubular piece that connects the tower4to the foundation14. Thereby, the transition piece15forms a transition between the foundation14and the tower4. An external platform (not shown) can be attached to the transition piece15. The tower4has a longitudinal direction L. The longitudinal direction L is oriented from the topmost tower section13toward the foundation14. However, the longitudinal direction L can be oriented vice versa. FIG.4shows an enlarged cutout of the wind turbine1. The lowest tower section9has a flange16that is connected to a flange17of the transition piece15. The transition piece15receives a platform arrangement18. The platform arrangement18is shown in a schematic perspective view inFIG.6, whereasFIG.7shows a schematic perspective view of another embodiment of the platform arrangement18. The platform arrangement18has a first or lower platform19and a second or upper platform20. The platforms19,20are arranged parallel to each other. When seen along the longitudinal direction L, the platforms19,20are spaced apart from each other. The upper platform20can be used to connect or to bolt the flanges16,17together. For this reason, the upper platform20can be named bolt tightening platform. A switch gear21is arranged on the lower platform19. For this reason, the lower platform19can be named switch gear platform. “Switch gear” in this context means an electric and/or electronic component that is part of an electric power system. The switch gear21can be composed of electrical disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical equipment. The switch gear21can be used both to de-energize equipment to allow work to be done and to clear faults downstream. The platform arrangement18has a plurality of support beams22to27. The support beams22to27(seeFIGS.6and7) run along the longitudinal direction L. The support beams22to27connect the platforms19,20to each other. There can be provided a carrying structure that carries the switch gear21. The carrying structure can be connected to the support beams22to27. In this way, the lower platform19does not have to carry the weight of the switch gear21. The number of support beams22to27is arbitrary. For example, there can be provided six support beams22to27. The support beams22to27are connected to the flange17by means of attachment elements28to30. The number of attachment elements28to30is the same as the number of support beams22to27. The wind turbine1has a service lift31for transporting technicians from the lower platform19to the nacelle3. The service lift31can be lowered to the lower platform19. The pull-in of the array cables and routing thereof toward the switch gear21is rather complicated due to the stiffness of the array cables, the lack of space or unstable temporary scaffold below the lower platform19. This makes the work below the switch gear21rather difficult inside the transition piece15or inside the tower4. Further, the service lift31needs access from below to be maintained. The design of the internal of the transition piece15, where the switch gear21is located, is often a cooperation between the wind turbine manufacturer and the manufacturer of the transition piece15. Hence, the result is often a new design that must be tested by means of mockups and workshops before it is shipped offshore prior to array cable installation to ensure that it will work and that there is sufficient space to handle the array cables. The solution for the service lift31has earlier been that the service lift31stops at the lowest platform within the tower4, namely in the lowest tower section9. A bolt connection platform below the connection between the tower4and the transition piece15can then be used as service area. Now turning back toFIG.4. To overcome the above mentioned drawbacks, an additional permanent working platform32that is arranged below the lower platform19is provided. As can be seen fromFIG.5, the working platform32, as also the platforms19,20are, is provided with support elements33to38that lie against the transition piece15from the inside thereof. The support elements33to38are assigned to the support beams22to27. The working platform32has an installation and/or service space39for installing and servicing the service lift31. Further, the working platform32has openings40,41for pulling in array cables (not shown) and easy handling of the array cables. The working platform32is also attached to the support beams22to27. The working platform32is arranged parallel to the lower platform19. When seen along the longitudinal direction L, the working platform32is arranged in a distance d of around 2.5 m away from the lower platform19. By having the permanent working platform32below the lower platform19where the switch gear21is located, there is provided a permanent solution for servicing the service lift31and for easing the routing and handling of the array cables. An airtight platform is arranged below the working platform32, and thereby the cable hang-off of the transition piece15is located approximately 2.5 m below the integrated working platform32. Hence, there is no need for additional scaffolding in the transition piece15for handling and routing the array cables. The integrated working platform32could either be suspended from the structure above by use of the support beams22to27, or it could be directly mounted to a wall42of the transition piece15by the use of stays or welded brackets. As can be seen fromFIG.6, the lower platform19has a centrally arranged hatch43that can be opened for array cable pull in. The lower platform19further has a support structure44that supports the lower platform19. The support structure44is attached to the support beams22to27. The support structure44can also be directly attached to the wall42. The support structure44comprises a plurality of beams that are arranged in a circular way. For security reasons, the lower platform19can have a handrail45. The working platform32can also be provided with a support structure46that supports the working platform32. The support structure46is attached to the support beams22to27and/or to the wall42. The support structure46comprises a plurality of beams that are arranged in a circular manner. The working platform32also has a handrail47. The working platform32has an elevated working section48that is provided below the switch gear21. The elevated working section48is arranged above the working platform32. The elevated working section48can be elevated 100 mm to 500 mm or more, desirably 300 mm, above the working platform32for a better reach toward the switch gear21. The advantages of the permanent working platform32are numerous; both in terms of saved hours during service of the service lift31and installing the array cables. It is also advantageous in terms of a more standardized interface towards the transition piece15, manufacturing, and thereby saving money on workshops, rescue drills, mockups and work instructions. For the service or installation of the service lift31, there is plenty of space on the working platform32below the lower platform19where the service lift31lands. Technicians can simply take a tower ladder49down one level to the working platform32. Then there is access to the bottom of the service lift31, to wire tensioners, guidewires etc. The center of the integrated working platform32is open and there is space for pulling array cables in, afterwards lower them down, coil them (if necessary) and then route them towards the switch gear21without having to erect additional scaffolding below the lower platform19. The working platform32is situated around the big center opening40. As can be seen fromFIG.7, alternatively, the integrated working platform32can be made as a smaller version that is only located below the service lift31. Hence, it is possible to do different setups of array cable routings. Advantageously, there is still access to the service space39for the service lift31. An alternative solution could be a suspended platform (not shown) rather than an integrated working platform32, especially if it is the smaller version according toFIG.7only for lift service access. It could be hoist into the transition piece15prior to installing the rest of the structure. Then the suspended platform could be attached before the transition piece15is transported offshore. For both alternatives above, the working platform32could be mounted to the wall42of the transition piece15as well, instead of being connected to the support beams22to27. Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention. For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements. | 10,864 |
11859593 | DETAILED DESCRIPTION FIG.1shows a wind turbine100erected at an installation site, having a tower102on which a nacelle104is mounted. A rotor arrangement106is mounted rotatably on nacelle104. Rotor arrangement106has a rotor hub110and rotor blades108. Rotor arrangement106drives a generator (not shown) for generating electric power. The tower102of wind turbine100comprises a tower section112,114,116, and a connector flange118(only hinted at inFIG.1) which is arranged at the bottom end of the tower section and adapted to join the tower section to a foundation embedded in the ground of the installation site, or to a foundation basket. FIGS.2aandbshow a tower section112according to a first preferred embodiment. As indicated in the Figures, tower section112is elastically deformed by applying deformation forces F1, F2in accordance with a method according to a first preferred embodiment. Tower section112has a wall120and a longitudinal axis L, with wall120extending along longitudinal axis L. Wall120forms the outer surface of the cylindrical tower section112. FIGS.2aand2bshow tower section112in a transport position, in which longitudinal axis L extends substantially in a horizontal direction. As is shown inFIG.2b, in particular, tower section112in the transport position has a vertical height h1in the relaxed state. According to the embodiment of tower section112shown here, the vertical height h1is constant in longitudinal direction L. In the present embodiment, tower section112has a round cross-section121with an area center M, cross-section121being constant along longitudinal axis L. AsFIG.2bshows, in order to elastically deform at least one portion of tower section112, deformation forces F1, F2are applied to wall120in such a way that, in an elastically deformed state (indicated by the broken lines) in the transport position shown, tower section112adopts a second height h2that is less than the first vertical height h1. Deformation forces F1, F2are applied orthogonally to the longitudinal direction L, the effective direction being in the direction of area center M, with the result that cross-section121of tower section112is deformed into a substantially oval shape. Deformation forces F1and F2are preferably of equal magnitude and in opposite directions. In the manner shown inFIG.2b, deformation forces F1, F2are applied to wall120uniformly and preferably at regular intervals along longitudinal axis L to wall120such that tower section112is elastically deformed uniformly along longitudinal axis L. FIGS.3aand3bshow a tower section114which has been elastically deformed by a method according to a second preferred embodiment. Tower section114has a wall120that extends along the longitudinal axis L, and a cross-section121, and tapers in portions in such a way that, in the transport position shown, height h1is a maximum height from which the vertical height decreases in the direction of the longitudinal axis L. In order to deform tower section114elastically, deformation forces F1, F2are applied to wall120in a locally confined manner in a region which is adjacent to the maximum height h1in the direction of the longitudinal axis. Tower section114thus deforms elastically only in the region adjacent the maximum height h1, the vertical height h1being reduced thereby to a second vertical height h2. According to the first embodiment, elastic deformation is preferably carried out by deformation forces F1, F2of equal magnitude acting in opposite directions, the effective direction of which is in the direction of area center M. The cross-section121shown in the Figure is round in the present case, but it can adopt any shape, wherein a round, oval or polygonal cross-sectional area is to be preferred. FIGS.4a-4cshow the elastic deformation of a tower section116by a method according to a third preferred embodiment. InFIG.4a, tower section116is shown in a transport position in which tower section116has a longitudinal axis L extending in the horizontal direction, a vertical height, and a wall120extending along the longitudinal axis. In the unstressed state in the transport position, tower section116has a constant maximum height h1. The tower section also has a cross-section121orthogonal to the longitudinal direction L and with an area center M. Wall120has two edge regions122that each have an edge124extending in a longitudinal direction L and which are spaced apart from each other in the circumferential direction. In the method in the embodiment shown, edges124are guided past each other to elastically deform section116, such that edge regions122overlap each other in the elastically deformed state of tower section116, as indicated inFIGS.4a-4c. According to the embodiment shown inFIG.4b, deformation forces F1, F2, which are preferably of the same magnitude and act in opposite directions, are applied to wall120in such a way, in order to elastically deform tower section116, that their effective direction is in the direction of the area center M of cross-section121. The elastic deformation of tower section116causes area center M to be displaced, and forces F1, F2follow the displacement of area center M, with the result that their effective direction is still at least approximately in the direction of the displaced area center M′. The deformation of tower section116as shown inFIG.4cdiffers from the embodiment shown inFIG.4bin that a deformation force F is applied eccentrically to wall120in edge region122, i.e., with an effective direction that is spaced apart from area center M. Compared to the embodiment shown inFIG.4b, this has the advantage that a reduced deformation force F is sufficient for elastic deformation of tower section116. According toFIGS.4band4c, wall120is deformed thereby in such a way that it curls into a spiral or helical shape in the side view. If a tower section116according toFIGS.4a-4cis provided, it is also necessary, before erecting the wind turbine100according toFIG.1, to join edges124to each other along the entire longitudinal axis L of tower section116before attaching tower section116to connector flange118. FIG.5shows tower section112in an unstressed state. Tower section112has a number of joining points126spaced apart from each other in the longitudinal direction L in wall120. Joining points126are adapted to be coupled to corresponding load introducing elements128,129(cf.FIGS.6,7and8) for applying a deformation force F to wall120. Joining points126are provided in the form of holes and in the transport position are arranged in the region of the maximum vertical height of tower section112. FIG.6shows an example of a load introducing element in the form of a bolt arrangement128comprising a number of bolts128aand a number of corresponding securing members128bfor securing bolts128a. AsFIG.5, in particular, shows, bolts128aare each engaged with a joining point126provided in the form of a hole in wall120. Bolt128ais secured by securing member128bin hole126. Securing member128bis provided in the form of a nut. The distance in longitudinal direction L between the individual load introducing elements128aand hence also between the corresponding joining points126is dependent on the wall thickness t and the maximum height h1of tower section112. For example, if the stress induced by deformation force F is no more than 300 N/m2, the wall thickness t is 60 mm and the elastic deformation as a result of applying a deformation force F in the direction of area center M, preferably 13 evenly distributed load introducing elements per meter are attached to wall120. Load introducing elements128acan be coupled to each other preferably by means of pull rods135or a strap or cable in order to apply the elastic deformation force. The deformation force F to be applied depends on the wall thickness t of wall120and the yield point or the 0.2% proof stress of the material being used and which the wall at least partly includes. After tower section112has been relieved of stress or load at the installation site following transportation, load introducing elements128apreferably remain in joining points126in order to reduce any weakening of tower section112as a result of the notch stresses. FIGS.7and8show a tower section112with load introducing elements129according to a second preferred embodiment. This embodiment differs from the embodiment shown inFIG.6in that load introducing elements129are thermally joined, preferably welded, to the inner side of wall120without any additional joining point. Load introducing elements129are provided in the form of metal sheets or plates with an edge extending substantially in the direction of longitudinal axis L, and which are joined thermally to the inner side of wall120. Load introducing elements129have recesses131which are preferably cylindrical and with which tensioning systems can be brought into engagement in order to apply a deformation force F to wall120. As shown inFIG.8, in particular, recesses131can be coupled to a tensioning system comprising a tensioning cable130and a cable winch or chain hoist132that is only outlined inFIG.8. Tensioning cable130is adapted to couple each of the load introducing elements129spaced apart in longitudinal direction L and arranged substantially in a row to at least one corresponding load introducing element129arranged spaced apart and substantially in a row in longitudinal direction L on the opposite wall. A first load introducing element129is preferably coupled by means of a tensioning cable130to only one opposite load introducing element129, with each of the following load introducing elements129being coupled to two load introducing elements129on the opposite wall, such that tensioning cable130is tensioned between the opposite portions of wall120and engages alternately with a respective load introducing element129. The last load introducing element in an edge portion of tower section112is coupled to only one opposite load introducing element129and is adapted to guide tensioning cable130in such a way that it engages with cable winch or chain hoist132to apply a deformation force F to each of load introducing elements129. The tower section is subsequently relieved of stress or load at the installation site in a preferably controlled manner by means of such a cable winch or chain hoist. Tower section112preferably comprises a plurality of tensioning systems that preferably have a tensioning cable130or tensioning strap and that can each be brought into engagement with some of the available load introducing elements129in the respective portion in order to apply a deformation force F to wall120. A plurality of tensioning systems are thus used to allow deformation force F to be introduced more evenly into the respective load introducing elements129coupled thereto. The same also applies to the embodiment shown inFIG.6. The load introducing elements128,129shown inFIGS.6-8can also be attached to a different position on wall120, for example to allow force to be applied eccentrically so as to elastically deform tower section112(cf.FIGS.4aand4c). FIG.9shows a perspective view of a connector flange118in a partly cutaway view. Connector flange118has a T-shaped cross-section134and comprises a base plate136and a web138. Base-side holes140are arranged in the region of base plate136. Base-side holes140are designed to connect connector flange118to a foundation or to a foundation basket at the installation site. Web138is preferably narrower in relation to base plate136, the thickness of web138preferably being adapted to the wall thickness t (cf.FIG.6) of the respective steel tower section112,114,116. In the region of web138, connector flange118also has a number of tower-side holes142that are distributed spaced apart from each other along the circumference of connector flange118. Tower-side holes142are designed to be brought into engagement with two guide plates144a, b. The first guide plate144ais disposed on an inside wall of web138and partly overlaps the web such that web138engages with tower-side holes142and the corresponding holes of guide plate144a. The second guide plate144bis disposed on the outwardly facing side of web138and partly overlaps web138in such a way that the holes of guide plate144bare in alignment with the corresponding tower-side holes142of web138and can be brought into engagement therewith by means of bolt or screw connections. Guide plates144a, bare arranged parallel to each other in such a way that a gap is formed between them with a thickness that is substantially equal to the wall thickness t (cf.FIG.6) of tower section112,114,116. To mount tower sections112,114,116(not shown, cf.FIGS.2a-8) on connector flange118, an end portion of tower section112,114,116can be guided into the gap formed between guide plates144a, band joined by means of a bolt or screw connection to the upper connection holes146of guide plates144a, b. Tower section112,114,116can be arranged in the gap in such a way that the connection holes (not shown) at the end portion of tower section112,114,116and the connection holes146of guide plates144a, bare aligned with each other. Bolts or screws can then be passed through connection holes146to join connector flange118to tower section112,114,116by a combination of bolting and clamping. FIGS.10and11show the transportation system148, which inFIG.10retains a tower section112according to a first preferred embodiment and inFIG.11a tower section116according to a third preferred embodiment in a transport position. InFIGS.10and11, tower sections112,116are retained in the transport position in an elastically deformed state in which they adopt vertical height h2, which is less than height h1in a relaxed state of the respective tower section112,116. To that end, transportation system148has a first and a second pivot bearing150a, b, each of which is designed to provide a support surface152for a portion of wall120of tower section112,116. Support surfaces152come into contact with an area of wall120. By means of the two pivot bearings150a, b, support surfaces152can be pivoted about a pivot point154of the pivot bearing so that the respective tower sections112,116can be retained not only in a relaxed, unstressed state, but also in an elastically deformed state in the transport position. LIST OF REFERENCE SIGNS 100Wind turbine 102Tower 104Nacelle 106Rotor arrangement 108Rotor blades 110Rotor hub 112,114,116Tower section 118Connector flange 120Wall 121Cross-section 122Edge regions 124Edge 126Joining point 128Bolt arrangement 128aBolt 128bSecuring member 129Steel plates 130Tensioning system, tensioning cable 131Recesses 132Cable winch, chain hoist 134T-shaped cross-section 136Base plate 138Web 140Base-side holes 142Tower-side holes 144a, bPair of guide plates 146Connection holes 148Transportation system 150a, bFirst and second pivot bearings 152Support surface 154Pivot point F, F1, F2Deformation force L Longitudinal axis h1First vertical height h2Second vertical height M Area center The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure. | 15,610 |
11859594 | DETAILED DESCRIPTION FIG.1schematically depicts a wind turbine10designed to perform the method according to the invention. To convert wind energy into electrical energy, the wind turbine10comprises a rotor13, which is fastened to a nacelle12mounted rotatably on a tower11, having two or three rotor blades14that are adjustable in terms of their blade angle. The rotor13drives a generator15, possibly with the interposition of a gear system. At least some of the electric power coming from the generator15is converted via a converter16and a transformer17in order to be supplied to a high- or medium-voltage grid18. The conversion is effected such that the electric power meets the requirements of the high- or medium-voltage grid17in terms of voltage amplitude, frequency and phase shift. In order to control the wind turbine10there is provision for a management system20, which is connected to the individual components of the wind turbine10and to various sensors via control lines, not shown. The management system20can act on the components of the wind turbine10such that the wind turbine10is operated at a desired operating point and the electrical energy is supplied in accordance with the requirements of the grid18. The management system20controls the wind turbine10on the basis of the measured values detected via the sensors and calculated or prescribed setpoint values, which are combined to form operational characteristic values24(seeFIGS.2and3), on the basis of parameterized control rules, the variable parameterization values of which can be combined in a parameter set. The management system20has a communication unit21, which is connected to the Internet40. Likewise connected to the Internet40is a server41having a database42. The server41and the management system20are designed to update a parameter set used by the management system20with a new parameter set, stored in the database42, in a known manner. The Internet40can furthermore also be used to supply control signals, for example from the grid operator, to the management system20. The wind turbine10furthermore comprises a safety system30for monitoring the wind turbine10on the basis of operational characteristic values provided via the management system20, diverted from the sensors of the management system20directly and/or ascertained by sensors separately intended for the safety system30. The operational characteristic values can be measured values and/or can be setpoint values ascertained or needing to be taken into consideration by the management system20. The safety system30is designed to transfer the wind turbine10to a safe plant state completely independently of the management system20, and hence for example in the event of complete failure of the management system20, if safety-critical operational characteristic values infringe safety parameters stored in the safety system30. In the exemplary embodiment depicted, the wind turbine10is stopped in such a case. The aforementioned safety parameters can be updated via the Internet40in accordance with the method according to the invention described below. As depicted schematically inFIG.2, sixty safety parameters51are combined with various safety features52.1,52.2,52.3,52.4,52.5to form a parameter block50and stored in the database42. The safety feature52.1is details concerning the type and configuration of the wind turbine10for which the parameter block50or the safety parameters51contained therein are intended. The safety feature52.2indicated is a maximum permissible operating period for the parameter block50, which can be used to ensure that the safety parameters51contained in the parameter block50are not used for longer than intended. Those details in the parameter block50that are not part of the safety parameters51(that is to say for example including the safety features52.1and52.2), and some of the safety parameters51, are encrypted (safety feature52.3), while the remainder of the safety parameters51are used to form a hash value (safety feature52.4). The entire parameter block50is additionally used to form a checksum (safety feature52.5) suitable for the cyclic redundancy check. The parameter block50can, if required, be transmitted from the server41via the Internet40to the communication unit21of the management system20, which in the example depicted is a distributed system having in each case a parameterized main control unit22and a blade angle control unit23, which take operational characteristic values24as a basis for controlling the wind turbine10on the basis of prescribed rules. The communication unit21transmits the parameter block50to the safety system30, which has a memory area31for received parameter blocks50. This can involve a single parameter block50being transmitted to the safety system30. It is alternatively possible for multiple parameter blocks50to be combined to form a parameter block set and then for just the latter to be transmitted. This can involve at least some of the described safety features, such as for example the checksum52.5, being ascertained not for each parameter block50of a parameter block set individually but rather just for the parameter block set as a whole. In the depicted exemplary embodiment in this instance the communication unit21already checks some of the safety features52of the parameter block50. As such, the checksum52.5is used to check whether the data transmission has taken place without error and, if not and if this is possible, to make a correction to the data via a cyclic redundancy check. It is subsequently checked whether the encrypted data52.3can be decrypted, and a check on the hash value52.4takes place. Only if these checks are completed successfully is the (decrypted) parameter block50supplied to the memory area31of the safety system30. The checks described above can alternatively also be performed directly by the safety system30, the communication unit21then forwarding the parameter block50merely as received to the safety system, and the checksum, hash value and encryption checks being performed there. The safety system30subsequently checks whether the details52.1concerning the type and configuration of the wind turbine10that are contained in the received parameter block50are concordant with the corresponding configuration parameters stored in the memory of the main control unit22of the management system20, with the configuration parameters being used as check information24.1. Alternatively, some of the check information24.1required for this comparison may also be selected by means of switching elements25, as are depicted inFIG.3. Additionally, the safety system30uses the validity period52.2to also check whether the loaded parameter block50is fundamentally valid. If one of the checks explained above has returned a negative result, the received parameter block50is marked as invalid and possibly erased from the memory area31. Depending on which of the above checks has had a negative outcome, the parameter block50in the memory area31can be subjected to the checks in question again, specifically at a later time, it then possibly being identified as valid. In particular if the check with a negative outcome cannot be expected to return a different result in future either, the parameter block50can also be rejected immediately. If the outcome of the checks is completely positive, the parameter block50in the memory area31of the safety system30persists and can be used for the actual monitoring of the wind turbine10. Besides the memory area31for received parameter blocks50, the safety system30also comprises a memory area34,34′ for default parameter blocks50′, one portion of the memory area34storing invariable default parameter blocks50′, for example permanently compiled in the control software, while the default parameter blocks50′ in the other portion of the memory area34′ can be updated in a similar manner to the described method for updating the parameter blocks50in the memory area31. One of the default parameter blocks50′ can be a universal default parameter block, which is valid for all modes of operation of the wind turbine and at any time. Owing to the general validity, this universal default parameter block can be permanently compiled in the control software and does not subsequently have to be subjected to any further safety check. The universal default parameter block can even define a safe plant state, in particular a stoppage or safe spin mode of the wind turbine, independently of the type and configuration of the wind turbine. FIG.3explains an ultimate use of parameter blocks50and default parameter blocks50′ for monitoring the wind turbine10. In principle, parameter blocks50and default parameter blocks50′ are used completely analogously in this instance, which is why the explanations below regarding the use of a default parameter block50′ also for loaded parameter blocks50, but with the proviso that the monitoring on the basis of a loaded parameter block50can take place only if a valid default parameter set is also available for the active mode of operation of the wind turbine10at the same time. The valid default parameter set can be in particular a universal default parameter set. In the variant embodiment depicted inFIG.3a large proportion of the safety features52.1-52.5, including those that have already been checked in connection with the transmission shown inFIG.2, are checked again. This, in some cases also repeated, checking of the safety features increases the reliability of the safety system30even further. InFIG.3the main control unit22has switching elements25that are used to specify the configuration of the wind turbine10, the type of which is stored as an operational characteristic value24. In the depicted exemplary embodiment the switching elements25are used to input for example a coding that is reflected by the types of the tower11, the rotor blades14, the generator15, the converter16and/or other components installed in the wind turbine10. Advantageously, the switching elements are in a form such that they allow a unique coding of the plant configuration. However, it is naturally also possible for the applicable information to be stored as a direct part of the configuration parameters24.1, in which case the switching elements25can be dispensed with. The switching elements25are arranged directly on the wind turbine10. The selection of the described coding directly in situ at the wind turbine10ensures that incorrect or intentionally manipulated parameter blocks50are not accepted, since they will fundamentally not match the plant configuration indicated by means of the coding. As an alternative to the rotary switches depicted inFIG.3, the switching element25can also comprise DIP switches, for example 32-bit DIP switches, which can easily be checked. The main control unit22of the management system20prescribes the present mode of operation of the wind turbine10to the safety system30as codes24.2available in the form of an operational characteristic value. Based on this code24.2the management system20first of all checks whether the memory area31contains a parameter block50that is valid for this mode of operation. If this is not the case the default parameter block50′ valid for the mode of operation is ascertained, the memory area34′ first being searched for valid default parameter blocks50′ in this case too before the default parameter blocks50′ and in the last instance possibly a universal default parameter set in the memory area34is resorted to. The default parameter blocks50′ are also resorted to (in the prescribed order) if a parameter block50that is fundamentally suitable for the present mode of operation, but for which the checks described below cannot all be completed with a positive result, is found in the memory area31. The same applies to the passage of default parameter blocks50′ from the memory area34′ and default parameter blocks50′ from the memory area34. If no valid parameter block50or default parameter block50′ at all is found for the present mode of operation, the wind turbine10is immediately stopped or transferred to a safe plant state. The latter can be achieved in particular by resorting to a universal default parameter set. Before a parameter block50or default parameter block50′ fundamentally identified by means of the mode of operation24.2is used, the safety system30uses comparison modules32to compare the configuration parameters24.1and possibly other general information24.3concerning the present mode of operation, and also the coding, allocated by means of the switching elements25, of the plant configuration, against corresponding safety features52in the parameter block50or default parameter block50′ that is to be checked. Only if all checks are completed with a positive result is the checked parameter block50or default parameter block50′ used for monitoring the wind turbine10. If this is not the case, then instead of the checked parameter block50or default parameter block50′ another, fundamentally possible, parameter block50or default parameter block50′ is checked in the order indicated above until a valid parameter block50or default parameter block50′ is found. If no valid parameter block50or default parameter block50′ is found, the wind turbine10is stopped or transferred to a safe plant state. This can be accomplished in particular by resorting to a universal default parameter set that defines the desired plant state. The parameter block50or default parameter block50′ currently used for monitoring is checked for its validity at regular intervals so as to be able to determine that the maximum permissible operating period has expired, for example. In this case the safety system30will ascertain a valid parameter block50or default parameter block50′ in the manner described. The actual monitoring of the operation of the wind turbine10is effected essentially as known from the prior art, which is why it only needs to be outlined briefly below. There is provision both in the main control unit22and in the blade angle control unit23for computation modules26that ascertain a check value from some respective predefined values among the operational characteristic values24available in each of the control units, said check value then being transmitted to the safety system30. There, the check value is compared against safety parameters51contained in the respective present parameter block50. If the check value is outside the range prescribed by the safety parameters51, the safety system30triggers an emergency stop for the wind turbine. Besides the check values supplied by the main control unit22and the blade angle control unit23, the safety system30also monitors directly measured values, for example in respect of the speed of the rotor13or the vibrations in the nacelle12, in the same way and stops the wind turbine10, or transfers it to a safe spin mode, if these values leave an operating range prescribed by means of safety parameters51of the respective present parameter block50,50′. These values, which are measured completely independently of the management system20, need to have particularly high demands placed on them in regard to the measured values being free of error, which is why particularly reliable sensors and evaluation electronics are preferably resorted to for these measured values. | 15,382 |
11859595 | DETAILED DESCRIPTION FIG.1shows a schematic view of a wind turbine40, wherein the power produced by the generator2is completely transferred to the electrolytic unit3. The generator2is coupled to the electrolytic unit3by an electric connection7. The electrolytic unit3comprises a system inlet4and a system outlet5. The electrolytic unit3is electrically powered by the generator2to produce hydrogen6. To produce the hydrogen6, water as the input fluid9enters through the system inlet4of the electrolytic unit3and is then transformed to hydrogen6in the electrolytic unit3by electric power coming from the generator2. The hydrogen6exits the electrolytic unit3by the system outlet5. FIG.2shows a schematic view of a wind turbine40, wherein the power produced by the generator2is transferred to the electricity grid8and to the electrolytic unit3. The electrolytic unit3works in the same way as shown inFIG.1. A power controlling device10is added in the electric connection7between the generator2and the electrolytic unit3to distribute the electric power between the generator2and the electrolytic unit3and between the generator2and the electricity grid8. In an embodiment, the amount of electric power can be varied depending on the demand for electric power and/or hydrogen6. FIG.3shows a schematic view of a wind turbine40comprising a safety system20. In an embodiment of the invention, the power produced by the generator2is completely transferred to the electrolytic unit3. The electrolytic unit3comprises a desalination unit11and an electrolytic device12, as well as a fluid connection between the desalination unit11and the electrolytic device12. The electrolytic device12and the desalination unit11are both powered by the generator2, which is connected to both devices by an electric connection7. The input fluid9for the electrolytic unit3is saltwater taken of the sea of the offshore wind turbine. In an embodiment, the system inlet4is a saltwater input13, where saltwater enters the wind turbine40. The saltwater enters the desalination unit11and the output of the desalination unit11is desalinated water14. The desalinated water14is then introduced in the electrolytic device12. Through the system outlet5of the wind turbine40, hydrogen6is taken out of the system through a hydrogen output15, as seawater is used as the input fluid9. The wind turbine40comprises a tower41on top of which a nacelle42is rotatably mounted. The wind turbine40further comprises a hub43which is connected to the nacelle42. A plurality of blades44are mounted on the hub43. The hub43is connected to a rotor and is rotatably mounted about a rotor axis by a main bearing. The area through which the blades44spin, as seen when directly facing the center of the blades44, is the swept area36. The wind turbine40further comprises a platform45on which the electrolytic unit3is arranged. In an embodiment of the invention, the safety system20of the wind turbine40is coupled to the electrolytic device12of the electrolytic unit3. The safety system20comprises a gas outlet21at a chimney22, thereby providing for an opening through which hydrogen6and other gases can be evacuated out of the electrolytic unit3. FIG.4shows another embodiment of a wind turbine40comprising a safety system20. In this embodiment, the electrolytic unit3is arranged on the platform45of the wind turbine40. The electrolytic unit3comprises four electrolytic devices12, a desalination unit11and electrical equipment16, such as control units or power converters, arranged in containers. The safety system20is arranged at four different corners of the platform45. The safety system20comprises a gas outlet21at a chimney22at each of the corners of the platform45where the safety system20is installed. FIG.5shows a schematic view of a possible arrangement of the components comprised in a safety system20on a platform of a wind turbine. In this embodiment, the electrolytic unit3is arranged on the platform45of the wind turbine40. The electrolytic unit3comprises two electrolytic devices12, a desalination unit11and electrical equipment16, such as control units or power converters. The safety system20is arranged at four different corners of the platform45. The safety system20comprises a gas outlet21at each of the corners of the platform45where the safety system20is installed. The gas outlets21are arranged at an angular distance24with respect to the tower41of the wind turbine40. FIG.6shows a safety system20comprising a chimney22installed on a platform45of a wind turbine40. In this embodiment, the gas outlet21of the chimney22is higher than the containers roof carrying the electrolytic devices12so that wind can carry away the evacuated gases. The chimney22shown here is fixed to the platform45, but it could in principle also be fixed to the container. As illustrated here, the top of the chimney22has a gas outlet21which is slightly tilted relative to the horizontal direction with the highest point facing away from the platform45, which ensures that the hydrogen6flows away from the platform45. FIGS.7and8show the control of a safety system20depending on the wind direction30. The gas outlets21of the safety system20in windward direction, i.e., directly facing the wind30or which are reached by the wind30on the first place, are closed gas outlets32. The gas outlets21in leeward direction, i.e., the rest of the gas outlets21are opened gas outlets31. This control strategy of gas outlets21helps to avoid that the hydrogen6evacuated by the opened gas outlets31expands over the platform45and therefore over electrical equipment, which may cause an explosion. It also reduces the risk of having explosive gas in the platform45area, where workers might be walking on. FIG.9shows a safety system20coupled to a plurality of electrolytic devices12. In contrast to the safety system20shown inFIGS.7and8, the safety system20shown inFIG.9comprises funnels38, which can work as an air inlet37if facing towards the wind30or as a gas outlet21to evacuate the hydrogen6. The funnel38acting as an air inlet37collects the air coming from the wind30and transports the air through the electrolytic devices12, thereby evacuating the electrolytic devices12from the hydrogen6, which is then expelled from the electrolytic unit3at the gas outlets21. The funnels38can be rotatable to maximize the amount of wind30taken in by facing the opening of the funnel38towards the wind direction. Depending on the wind direction, the funnels38will collect the wind30as air inlets37or evacuate the hydrogen6as gas outlets21. A safety system20as shown inFIG.9can also be used in the setup as shown inFIGS.7and8, i.e., having a funnel38at each corner of the platform45, and following a similar control strategy to avoid that the hydrogen6stays at the platform45area. FIG.10shows a safety system20coupled to a distributor system35and to an electrolytic unit3. In this case, the safety system20comprises four funnels38arranged at an angular distance24of 90° to the neighboring funnels38. This angular distance24or a rectangular arrangement of the funnels38, where each funnel38is arranged at the corner of the rectangle, is particularly useful for an efficient arrangement on the platform45. As shown here, the funnel38facing the wind30acts as an air inlet37, collecting the air, which is transported to a distributor system35, which distributes the air to each module of the electrolytic unit3containing hydrogen6and evacuates the electrolytic unit3from the hydrogen6. The hydrogen6is then released to the atmosphere by the rest of the funnels38through the gas outlets21. A safety system20as shown inFIG.10can also be used in the setup as shown inFIGS.7and8, i.e., having a funnel38at each corner of the platform45, and following a similar control strategy to avoid that the hydrogen6stays at the platform45area. FIG.11shows a control strategy of a safety system20. Triggered by the approach of a vessel46to the wind turbine40location, the electrolytic unit3of the wind turbine40is automatically evacuated. The safety system20can also be triggered manually by a signal. The safety system20shown here comprises both a chimney22and a gas outlet21to release the hydrogen6to the atmosphere, as well as a gas outlet valve34at the system outlet5to bring the hydrogen6through a piping network to the onshore location. Releasing the hydrogen6at the swept area36of the blades44should be avoided. In an embodiment, if not enough wind44is available to carry the hydrogen6away, then instead of releasing the hydrogen6to the atmosphere, the hydrogen6can be evacuated through the gas outlet valve34. Additionally, the electrolytic unit3can be depressurized with a vacuum to ensure that the hydrogen6is completely evacuated. The electrolytic unit3can alternatively be flushed with air or other non-explosive gases, such as CO2 or halon-based gases commonly used in fire protection. Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention. For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements. REFERENCE LIST 2Generator3Electrolytic unit4System inlet5System outlet6Hydrogen7Electric connection8Electricity grid9Input fluid10Power controlling device11Desalination unit12Electrolytic device13Saltwater input14Desalinated water15Hydrogen output16Electrical equipment20Safety system21Gas outlet22Chimney23System outlet valve24Angular distance30Wind31Opened gas outlet32Closed gas outlet34Gas outlet valve35Distributor system36Swept area37Air inlet38Funnel40Wind turbine41Tower42Nacelle43Hub44Blades45Platform46Vessel | 9,879 |
11859596 | In the figures:1wind power electricity supply device;2solar energy electricity supply device;3CO2energy storage device;4control device;5early warning device;6remote operation device;7junction box;8wire;9insulating anticorrosive layer;10electric tracing bands;11stainless steel cable tie;12inner steel pipe body;13sandwich layer;14protecting pipe;15temperature sensor;16pressure sensor;17valve structure;18through groove;19outer steel pipe protecting body;20flange;21pipe clamp;22connecting bolt;23connecting nut. DETAILED DESCRIPTION Specific embodiments of the present invention are further described below in combination with the drawings and the technical solution. As shown inFIGS.1-3, the present embodiment discloses an electric heating thermal management system for an oil and gas transportation pipeline based on renewable energy and CO2energy storage, comprising a renewable energy electricity supply device, a CO2energy storage device3, a control device4, an early warning device5, a remote operation device6, and an electric heating device of an oil and gas transportation pipeline. The energy source of the renewable energy electricity supply device comprises, but not limited to, offshore solar energy, wind energy or ocean current energy, and comprises a wind power electricity supply device1and a solar energy electricity supply device2in the present embodiment. The CO2energy storage device3is coupled with the renewable energy electricity supply device; the CO2energy storage device3processes and then transmits the stored electric energy to the control device4; the control device4distributes the electric energy to the electric heating device of the oil and gas transportation pipeline after unified coordination, which can provide steady and continuous power output for the electric heating device and avoid the fluctuation and intermittency of the renewable energy electricity supply device; at the same time, the CO2energy storage device3can also provide CO2gas; and CO2is transported through the pipeline in a supercritical state and injected into a seabed storage body, so as to achieve safe and efficient exploitation of reservoir oil and gas and long-term stable geological storage of CO2. However, in a deep-sea environment, the decrease of the temperature in a CO2gas transportation pipeline will lead to the change of CO2gas state, which will affect the transportation, storage amount and storage efficiency of CO2in the storage body. When moisture exists in the CO2gas transportation pipeline, due to the conditions of low temperature and high pressure on the seabed, solid matters such as hydrates are easy to form in the transportation pipeline and block the pipeline. The electric heating device of the oil and gas transportation pipeline provided by the present invention is also suitable for this case. The control device4dynamically schedules the electric energy provided by the CO2energy storage device2; relying on a plurality of groups of junction boxes7arranged on the device, a plurality of groups of wires8are arranged in the plurality of groups of junction boxes7; the plurality of groups of wires8are wrapped by insulators; and the wires8are used for providing electric energy for the electric heating device of the oil and gas transportation pipeline and controlling the electric tracing bands at different positions to produce different thermal responses. The early warning device5is connected with the control device4and the remote operation device6respectively and used for analyzing and processing signals transmitted by the control device4and making a response in time, wherein the early warning device5has an intelligent mode and anartificial mode. The intelligent mode: when data values fed back by the temperature sensor15and the pressure sensor16reach a preset temperature threshold and a preset pressure threshold, an intelligent command control device4energizes the electric tracing bands10so that oil and gas temperature in the oil and gas transportation pipeline is always kept above the critical temperature for formation of the solid matters such as wax crystals and hydrates. The artificial mode: the early warning device transmits a signal to the remote operation device6; and a field operator instructs the control device to set different parameters to energize the electric tracing bands10at different positions, strictly controls the heating temperature, and can combine with an inhibitor to jointly act according to current heating temperature to ensure the safe and effective operation of the transportation pipeline at low cost. The electric heating device of the oil and gas transportation pipeline is used for preventing and controlling solid matters in the oil and gas transportation pipeline to ensure the safe and effective operation of the transportation pipeline. The electric heating device of the oil and gas transportation pipeline is provided with an inner steel pipe body12, an insulating anticorrosive layer9, the electric tracing bands10, a sandwich layer13, an outer steel pipe protecting body19and a pipe clamp21from inside to outside. The insulating anticorrosive layer9can be selected from insulating anticorrosive paint or insulating anticorrosive film coated or wrapped on the outer wall of the inner steel pipe body12, which is not only conducive to the mitigation of pipeline corrosion, but also can extend the service life of the electric tracing bands10. Thermal insulation material is filled in the sandwich layer13; and the thermal insulation material comprises, but not limited to, epoxy resin and composite polypropylene to reduce heat dissipation time and heat dissipation amount of the oil and gas transportation pipeline. The electric tracing bands10are arranged as heating elements and installed at the outer side of the insulating anticorrosive layer; and in combination with the arrangement modes of direct laying along the axial direction of the pipeline at a straight pipe section and S-shaped arrangement at the elbow section or valve connection, not only the influence of poor heating effect caused by large resistance difference in different positions of the heating elements is reduced, but also the heating amount of the oil and gas transportation pipeline in the easily blocked position is enough, thereby effectively preventing the formation of the solid matters. In addition, stainless steel cable ties11as fasteners are used for fastening the electric tracing bands10onto the inner steel pipe body12in a form of spaced arrangement; the oil and gas pipeline is connected and docked with a valve structure17through a flange20; the flange20is fastened by a plurality of connecting bolts22and connecting nuts23; and through holes through which the electric tracing bands10penetrate are reserved on the flange20to realize secondary fastening for the electric tracing bands. The oil and gas transportation pipeline adopts a thermal insulation structure of a pipe sleeve pipe sandwich, which not only can satisfy the requirements of pressure resistance and heat preservation of submarine pipelines, but also can arrange the electric tracing bands10in the sandwich layer13, with convenience in arrangement. When the required number of the electric tracing bands10is greater than one, the electric tracing bands10are uniformly arranged on the axial center of the inner steel pipe body12. The original structure of the oil and gas transportation pipeline is not damaged. Compared with the unblocking mode of heating with a heating layer arranged on the inner wall of the pipeline, the limitation of material development on the heating elements at the inner wall of the pipeline is avoided. This structure has higher engineering applicability. The temperature sensor15and the pressure sensor16extend through the top of the three-way valve to the inner top end of the inner steel pipe body12, and a protecting pipe14is arranged on the outer side, which can ensure full contact with the oil and gas inside the pipeline, and can also ensure the service life of a data collecting device. Compared with laying of a temperature sensing device on the outer wall of the oil and gas pipeline, the monitored data is more accurate, which is conducive to the correct judgment of the early warning device. The protecting pipe14, the temperature sensor15and the pressure sensor16are embedded in the valve structure in advance in an actual construction process, and are connected into a whole through a sealing technology to reduce the construction difficulty. The pipe clamps21arranged on the outer steel pipe protecting body19at intervals comprise two semicircular upper pipe clamp and lower pipe clamp; and the upper pipe clamp and the lower pipe clamp are connected through a plurality of bolts and nuts. A through groove18arranged below the pipe clamp21penetrates through the through holes reserved on the sandwich layer13and the outer steel pipe protecting body19as required, and to the electric tracing band joints, wherein the wires of the temperature sensor15, the pressure sensor16and the electric tracing bands10are arranged in the through groove18to effectively protect the service life of the wires and make management more convenient. Through this structure, a plurality of groups of wires arranged on the control device can be connected with the electric tracing band joints in different positions; hierarchical and distributed management for the oil and gas transportation pipeline can be conducted in unblocked, easily blocked and blocked positions of the oil and gas transportation pipeline, thereby solving the problem of the influence on a heating effect caused by continuous heating for the oil and gas transportation pipeline and excessive heating length of the electric tracing bands in existing projects, reducing the management cost of the oil and gas transportation pipeline and also improving management efficiency. The above electric heating thermal management system for the oil and gas transportation pipeline based on renewable energy and CO2energy storage comprises the work steps:Step 1, when there is wind energy at sea, wind power is used to drive windmill blades to rotate, and then the speed of rotation is increased by a speed increaser to promote a generator to generate electricity; when there is solar radiation at sea, a photovoltaic effect is used to convert solar radiation energy into electric energy; and electric energy generated by the offshore wind power electricity supply device1and the offshore solar energy electricity supply device2is transported to the CO2energy storage device3for storage;Step 2, the CO2energy storage device3processes and then transmits the stored electric energy to the control device4; and the control device4distributes the electric energy to the electric heating device of the oil and gas transportation pipeline after unified coordination;Step 3, the temperature sensor15and the pressure sensor16arranged on the valve structure17feed back the monitoring data in the pipeline to the control device4in real time;Step 4, the control device4receives the feedback data in real time, and synchronously outputs the data to the early warning device5;Step 5, the early warning device5presets the temperature threshold and the pressure threshold for solid matter generation in oil and gas transportation pipeline; when the feedback data value reaches the preset value, the early warning device5sends out a control signal intelligently, and commands the control device4to energize the electric heating device of the oil and gas transportation pipeline so that oil and gas temperature in the oil and gas transportation pipeline is always kept above the critical temperature for solid matter formation; meanwhile, the early warning device5synchronizes the feedback data to the remote operation device6; and a field operator instructs the control device4to set different parameters to energize the electric tracing bands10at different positions according to the fluctuation of the feedback value around the range of the temperature threshold and the pressure threshold, strictly controls the heating temperature, and avoids the loss of the electric energy caused by excessive heating. If the parameters in the pipeline are close to the generation condition of solid matters or a few solid matters are generated in the pipeline but do not affect the oil and gas transportation at this moment, the field operator can increase the heating temperature slightly and combine with an inhibitor to jointly act to ensure the safe and effective operation of the transportation pipeline on the premise of low cost. On the contrary, if the parameters in the pipeline obviously exceed the generation condition of solid matters or more solid matters can be judged to be generated at this moment, the field operator should increase the heating amount, and can stop the oil and gas transportation in serious cases, to avoid causing huge economic losses. | 13,003 |
11859597 | Like reference symbols in the various drawings indicate like elements unless otherwise indicated. DETAILED DESCRIPTION This invention relates to electrical power generation using Ocean Thermal Energy Conversion (OTEC) technology. Aspects of the invention relate to a floating OTEC power plant having improved overall efficiencies with reduced parasitic loads, greater stability, lower construction and operating costs, and improved environmental footprint over previous OTEC power plants. Other aspects include large volume water conduits that are integral with the floating structure. Modularity and compartmentation of the multi-stage OTEC heat engine reduces construction and maintenance costs, limits off-grid operation and improves operating performance. Still further aspects provide for a floating platform having integrated heat exchange compartments and provides for minimal movement of the platform due to wave action. The integrated floating platform may also provide for efficient flow of the warm water or cool water through the multi-stage heat exchanger, increasing efficiency and reducing the parasitic power demand. Aspects of the invention promote a neutral thermal footprint by discharging warm and cold water at appropriate depth/temperature ranges. Energy extracted in the form of electricity reduces the bulk temperature to the ocean. OTEC is a process that uses heat energy from the sun that is stored in the Earth's oceans to generate electricity. OTEC utilizes the temperature difference between the warmer, top layer of the ocean and the colder, deep ocean water. Typically this difference is at least 36° F. (20° C.). These conditions exist in tropical areas, roughly between the Tropic of Capricorn and the Tropic of Cancer, or even 20° north and south latitude. The OTEC process uses the temperature difference to power a Rankine cycle, with the warm surface water serving as the heat source and the cold deep water serving as the heat sink. Rankine cycle turbines drive generators which produce electrical power. FIG.1illustrates a typical OTEC Rankine cycle heat engine10which includes warm sea water inlet12, evaporator14, warm sea water outlet15, turbine16, cold sea water inlet18, condenser20, cold sea water outlet21, working fluid conduit22and working fluid pump24. In operation, heat engine10can use any one of a number of working fluids, for example commercial refrigerants such as ammonia. Other working fluids can include propylene, butane, R-22 and R-134a. Other commercial refrigerants can be used. Warm sea water between approximately 75° and 85° F., or more, is drawn from the ocean surface or just below the ocean surface through warm sea water inlet12and in turn warms the ammonia working fluid passing through evaporator14. The ammonia boils to a vapor pressure of approximately 9.3 atm. The vapor is carried along working fluid conduit22to turbine16. The ammonia vapor expands as it passes through the turbine16, producing power to drive an electric generator25. The ammonia vapor then enters condenser20where it is cooled to a liquid by cold sea water drawn from a deep ocean depth of approximately 3000 ft. The cold sea water enters the condenser at a temperature of approximately 40° F. The vapor pressure of the ammonia working fluid at the temperature in the condenser20, approximately 51° F., is 6.1 atm. Thus, a significant pressure difference is available to drive the turbine16and generate electric power. As the ammonia working fluid condenses, the liquid working fluid is pumped back into the evaporator14by working fluid pump24via working fluid conduit22. The heat engine10ofFIG.1is essentially the same as the Rankine cycle of most steam turbines, except that OTEC differs by using different working fluids and lower temperatures and pressures. The heat engine10of theFIG.1is also similar to commercial refrigeration plants, except that the OTEC cycle is run in the opposite direction so that a heat source (e.g., warm ocean water) and a cold heat sink (e.g., deep ocean water) are used to produce electric power. FIG.2illustrates the typical components of a floating OTEC facility200, which include: the vessel or platform210, warm sea water inlet212, warm water pump213, evaporator214, warm sea water outlet215, turbine-generator216, cold water pipe217, cold sea water inlet218, cold water pump219, condenser220, cold sea water outlet221, working fluid conduit22, working fluid pump224, and pipe connections230. OTEC facility200can also include electrical generation, transformation and transmission systems, position control systems such as propulsion, thrusters, or mooring systems, as well as various auxiliary and support systems (for example, personnel accommodations, emergency power, potable water, black and grey water, fire fighting, damage control, reserve buoyancy, and other common shipboard or marine systems.). Implementations of OTEC power plants utilizing the basic heat engine and system ofFIGS.1and2have a relatively low overall efficiency of 3% or below. Because of this low thermal efficiency, OTEC operations require the flow of large amounts of water through the power system per kilowatt of power generated. This in turn requires large heat exchangers having large heat exchange surface areas in the evaporator and condensers. Such large volumes of water and large surface areas require considerable pumping capacity in the warm water pump213and cold water pump219, reducing the net electrical power available for distribution to a shore-based facility or on board industrial purposes. Moreover, the limited space of most surface vessels, does not easily facilitate large volumes of water directed to and flowing through the evaporator or condenser. Indeed, large volumes of water require large diameter pipes and conduits. Putting such structures in limited space requires multiple bends to accommodate other machinery. And the limited space of typical surface vessels or structures does not easily facilitate the large heat exchange surface area required for maximum efficiency in an OTEC plant. Thus the OTEC systems and vessel or platform have traditional been large and costly. This has lead to an industry conclusion that OTEC operations are a high cost, low yield energy production option when compared to other energy production options using higher temperatures and pressures. Aspects of the invention address technical challenges in order to improve the efficiency of OTEC operations and reduce the cost of construction and operation. The vessel or platform210requires low motions to minimize dynamic forces between the cold water pipe217and the vessel or platform210and to provide a benign operating environment for the OTEC equipment in the platform or vessel. The vessel or platform210should also support cold and warm water inlet (218and212) volume flows, bringing in sufficient cold and warm water at appropriate levels to ensure OTEC process efficiency. The vessel or platform210should also enable cold and warm water discharge via cold and warm water outlets (221and215) well below the waterline of vessel or platform210to avoid thermal recirculation into the ocean surface layer. Additionally, the vessel or platform210should survive heavy weather without disrupting power generating operations. The OTEC heat engine10should utilize a highly efficient thermal cycle for maximum efficiency and power production. Heat transfer in boiling and condensing processes, as well as the heat exchanger materials and design, limit the amount of energy that can be extracted from each pound of warm seawater. The heat exchangers used in the evaporator214and the condenser220require high volumes of warm and cold water flow with low head loss to minimize parasitic loads. The heat exchangers also require high coefficients of heat transfer to enhance efficiency. The heat exchangers can incorporate material and design that may be tailored to the warm and cold water inlet temperatures to enhance efficiency. The heat exchanger design should use a simple construction method with minimal amounts of material to reduce cost and volume. Turbo generators216should be highly efficient with minimal internal losses and may also be tailored to the working fluid to enhance efficiency FIG.3illustrates an implementation of the present invention that enhances the efficiency of previous OTEC power plants and overcomes many of the technical challenges associated therewith. This implementation comprises a spar for the vessel or platform, with heat exchangers and associated warm and cold water piping integral to the spar. OTEC Spar310houses an integral multi-stage heat exchange system for use with an OTEC power generation plant. Spar310includes a submerged portion311below waterline305. Submerged portion311comprises warm water intake portion340, evaporator portion344, warm water discharge portion346, condenser portion348, cold water intake portion350, cold water pipe351, cold water discharge portion352, machinery deck portion354. A deck house360sets atop the spar housing the electrical switchyard, auxiliary and emergency machinery and systems, boat handling equipment, and manned spaces such as office, accommodations, communications center and control rooms. FIG.3Aillustrates an exemplary machinery layout of the present invention, including warm water intake portion340, warm water pump room341, stacked evaporator portion344, turbine generator349, stacked condenser portion348, cold water intake portion350, and cold water pump room351. In operation, warm sea water of between 75° F. and 85° F. is drawn through warm water intake portion340and flows down the spar though structurally integral warm water conduits not shown. Due to the high volume water flow requirements of OTEC heat engines, the warm water conduits direct flow to the evaporator portion344of between 500,000 gpm and 6,000,000 gpm. Such warm water conduits have a diameter of between 6 ft and 35 ft, or more. Due to this size, the warm water conduits are vertical structural members of spar310. Warm water conduits can be large diameter pipes of sufficient strength to vertically support spar310. Alternatively, the warm water conduits can be passages integral to the construction of the spar310. Warm water then flows through the evaporator portion344which houses one or more stacked, multi-stage heat exchangers for warming a working fluid to a vapor. The warm sea water is then discharged from spar310via warm water discharge346. Warm water discharge can be located or directed via a warm water discharge pipe to a depth at or close to an ocean thermal layer that is approximately the same temperature as the warm water discharge temperature to minimize environmental impacts. The warm water discharge can be directed to a sufficient depth to ensure no thermal recirculation with either the warm water intake or cold water intake. Cold sea water is drawn from a depth of between 2500 and 4200 ft, or more, at a temperature of approximately 40° F., via cold water pipe351. The cold sea water enters spar310via cold water intake portion350. Due to the high volume water flow requirements of OTEC heat engines, the cold sea water conduits direct flow to the condenser portion348of between 500,000 gpm and 3,500,000 gpm. Such cold sea water conduits have a diameter of between 6 ft and 35 ft, or more. Due to this size, the cold sea water conduits are vertical structural members of spar310. Cold water conduits can be large diameter pipes of sufficient strength to vertically support spar310. Alternatively, the cold water conduits can be passages integral to the construction of the spar310. Cold sea water then flows upward to stacked multi-stage condenser portion348, where the cold sea water cools a working fluid to a liquid. The cold sea water is then discharged from spar310via cold sea water discharge352. Cold water discharge can be located or directed via a cold sea water discharge pipe to depth at or close to an ocean thermal layer that is approximately the same temperature as the cold sea water discharge temperature. The cold water discharge can be directed to a sufficient depth to ensure no thermal recirculation with either the warm water intake or cold water intake. Machinery deck portion354can be positioned vertically between the evaporator portion344and the condenser portion348. Positioning machinery deck portion354beneath evaporator portion344allows nearly straight line warm water flow from intake, through the multi-stage evaporators, and to discharge. Positioning machinery deck portion354above condenser portion348allows nearly straight line cold water flow from intake, through the multi-stage condensers, and to discharge. Machinery deck portion354includes turbo-generators356. In operation warm working fluid heated to a vapor from evaporator portion344flows to one or more turbo generators356. The working fluid expands in turbo generator356thereby driving a turbine for the production of electrical power. The working fluid then flows to condenser portion348where it is cooled to a liquid and pumped to evaporator portion344. The performance of heat exchangers is affected by the available temperature difference between the fluids as well as the heat transfer coefficient at the surfaces of the heat exchanger. The heat transfer coefficient generally varies with the velocity of the fluid across the heat transfer surfaces. Higher fluid velocities require higher pumping power, thereby reducing the net efficiency of the plant. A hybrid cascading multi-stage heat exchange system facilitates lower fluid velocities and greater plant efficiencies. The stacked hybrid cascade heat exchange design also facilitates lower pressure drops through the heat exchanger. And the vertical plant design facilitates lower pressure drop across the whole system. A hybrid cascading multi-stage heat exchange system is described in U.S. patent application Ser. No. 12/691,663, entitled “Ocean Thermal Energy Conversion Plant,” filed on Jan. 21, 2010, the entire contents of which are incorporated herein by reference. Cold Water Pipe As described above, OTEC operations require a source of cold water at a constant temperature. Variations in the cooling water can greatly influence the overall efficiency of the OTEC power plant. As such, water at approximately 40° F. is drawn from depths of between 2700 ft and 4200 ft or more. A long intake pipe is needed to draw this cold water to the surface for use by the OTEC power plant. Such cold water pipes have been an obstacle to commercially viable OTEC operations because of the cost in constructing a pipe of suitable performance and durability. Such cold water pipes have been an obstacle to commercially viable OTEC operations because of the cost in constructing a pipe of suitable performance and durability. OTEC requires large volumes of water at desired temperatures in order to ensure maximum efficiency in generating electrical power. Previous cold water pipe designs specific to OTEC operations have included a sectional construction. Cylindrical pipe sections were bolted or mechanically joined together in series until a sufficient length was achieved. Pipe sections were assembled near the plant facility and the fully constructed pipe was then upended and installed. This approach had significant drawbacks including stress and fatigue at the connection points between pipe sections. Moreover, the connection hardware added to the overall pipe weight, further complicating the stress and fatigue considerations at the pipe section connections and the connection between the fully assembled CWP and the OTEC platform or vessel. The cold water pipe (“CWP”) is used to draw water from the cold water reservoir at an ocean depth of between 2700 ft and 4200 ft or more. The cold water is used to cool and condense to a liquid the vaporous working fluid emerging from the power plant turbine. The CWP and its connection to the vessel or platform are configured to withstand the static and dynamic loads imposed by the pipe weight, the relative motions of the pipe and platform when subjected to wave and current loads of up to 100-year-storm severity, and the collapsing load induced by the water pump suction. The CWP is sized to handle the required water flow with low drag loss, and is made of a material that is durable and corrosion resistant in sea water. The cold water pipe length is defined by the need to draw water from a depth where the temperature is approximately 40° F. The CWP length can be between 2000 feet and 4000 ft or more. In aspects of the present invention the cold water pipe can be approximately 3000 feet in length. The CWP diameter is determined by the power plant size and water flow requirements. The water flow rate through the pipe is determined by the desired power output and OTEC power plant efficiency. The CWP can carry cold water to the cold water conduit of the vessel or platform at a rate of between 500,000 gpm and 3,500,000 gpm, or more. Cold water pipe diameters can be between 6 feet and 35 feet or more. In aspects of the present invention, the CWP diameter is approximately 31 feet in diameter. Previous cold water pipe designs specific to OTEC operations have included a sectional construction. Cylindrical pipe sections of between 10 and 80 feet in length were bolted or joined together in series until a sufficient length was achieved. Using multiple cylindrical pipe sections, the CWP could be assembled near the plant facility and the fully constructed pipe could be upended and installed. This approach had significant drawbacks including stress and fatigue at the connection points between pipe sections. Moreover, the connection hardware added to the overall pipe weight, further complicating the stress and fatigue considerations at the pipe section connections and the connection between the fully assembled CWP and the OTEC platform or vessel. Referring toFIG.4a continuous offset staved cold water pipe is shown. The cold water pipe451is free of sectional joints as in previous CWP designs, instead utilizing an offset stave construction. CWP451includes a top end portion452for connection to the submerged portion of the floating OTEC platform411. Opposite top end portion452is bottom portion454, which can include a ballast system, an anchoring system, and/or an intake screen. CWP451comprises a plurality of offset staves constructed to form a cylinder. In an aspect the plurality of offset staves can include alternating multiple first staves465and multiple second staves467. Each first stave includes a top edge471and a bottom edge472. Each second stave includes a top edge473and a bottom edge474. In an aspect, second stave467is vertically offset from an adjacent first stave portion465such that top edge473(of second stave portion467) is between 3% and 97% vertically displaced from the top edge471(of first stave portion465). In further aspects, the offset between adjacent staves can be approximately, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or more. FIG.5illustrates a detail view of an offsetting stave pattern of an aspect of the present invention. The pattern includes multiple first staves465, each having a top edge portion471, bottom edge portion472, connected edge480and offset edge478. The pattern also includes multiple second staves467, each having a top edge portion473, a bottom edge portion474, connected edge480, and offset edge479. In forming the cold water pipe, first stave section465is joined to second stave section467such that connected edge480is approximately 3% to 97% of the length of first stave section465when measured from the top edge471to the bottom edge472. In an aspect, connected edge480is approximately 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90% of the length of the stave. It will be appreciated that in a fully constructed pipe, first stave465can be joined to second stave467along connected edge480. First stave465can also be connected to additional staves along offset edge478, including an additional first stave portion, an additional second stave portion, or any other stave portion. Similarly, second stave467can be joined to first stave portion along connected edge480. And second stave467can be joined to another stave along offset edge479, including an additional first stave portion, an additional second stave portion, or any other stave portion. In aspects, the connected edge480between the multiple first staves465and the multiple second staves467can be a consistent length or percentage of the stave length for each stave about the circumference of the pipe. The connected edge480between the multiple first staves465and the multiple second staves465can be a consistent length or percentage of the stave length for each stave along the longitudinal axis of the cold water pipe451. In further aspects the connected edge480can vary in length between alternating first staves465and second staves467. As illustrated inFIG.5, first stave465and second stave467have the same dimensions. In aspects, first stave465can be between 30 and 130 inches wide or more, 30 to 60 feet long, and between 1 and 24 inches thick. In an aspect the stave dimensions can be approximately 80 inches wide, 40 feet long, and 4 to 12 inches thick. Alternatively, first stave465can have a different length or width from second stave467. FIG.6illustrates a cross sectional view of cold water pipe451showing alternating first staves465and second staves467. Each stave includes an inner surface485and an outer surface486. Adjacent staves are joined along connected surface480. Any two connected surfaces on opposite sides of a single stave define an angle α. The angle α is determined by dividing 360° by the total number of staves. In an aspect, α can be between 1° and 36°. In an aspect α can be 22.5° for a 16 stave pipe or 11.25° for a 32 stave pipe. Individual staves of cold water pipe451can be made from polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), fiber reinforced plastic (FRP), reinforced polymer mortar (RPMP), polypropylene (PP), polyethylene (PE), cross-linked high-density polyethylene (PEX), polybutylene (PB), acrylonitrile butadiene styrene (ABS); polyurethane, polyester, fiber reinforced polyester, nylon reinforce polyester, vinyl ester, fiber reinforced vinyl ester, nylon reinforced vinyl ester, concrete, ceramic, or a composite of one or more thereof. Individual staves can be molded, extruded, or pulltruded using standard manufacturing techniques. In one aspect, individual staves are pulltruded to the desired shape and form and comprise a fiber or nylon reinforced vinyl ester. Vinyl esters are available from Ashland Chemical of Covington, Kentucky. In an aspect, staves are bonded to adjacent staves using a suitable adhesive. A flexible resin can be used to provide a flexible joint and uniform pipe performance. In aspects of the invention, staves comprising a reinforced vinyl ester are bonded to adjacent staves using a vinyl ester resin. Methacrylate adhesives can also be used, such as MA560-1 manufactured by Plexis Structural Adhesives of Danvers, Massachusetts. Referring toFIGS.7A-7C, various stave constructions are shown wherein an individual stave465includes a top edge471, a bottom edge472and one or more voids475. Void475can be hollow, filled with water, filled with a resin, filled with an adhesive, or filled with a foam material, such as syntactic foam. Syntactic foam is a matrix of resin and small glass beads. The beads can either be hollow or solid. Void475can be filled to influence the buoyancy of the stave and/or the cold water pipe451.FIG.7Aillustrates a single void475. In an aspect multiple voids475can be equally spaced along the length of the stave, as illustrated inFIG.7B. In an aspect, one or more voids475can be placed toward one end of the stave, for example toward the bottom edge472, as illustrated inFIG.7C. Referring toFIG.8, each individual stave465can include a top edge471, a bottom edge472, a first longitudinal side491and a second longitudinal side492. In an aspect, longitudinal side491includes a joinery member, such as tongue493. The joinery member can alternatively include, biscuits, half-lap joints, or other joinery structures. Second longitudinal side492includes a mating joinery surface, such as groove494. In use, the first longitudinal side491of a first stave mates or joins with the second longitudinal side492of a second stave. Though not shown, joining structures, such as tongue and groove, or other structures can be used at the top edge471and the bottom edge472to join a stave to a longitudinally adjacent stave. In aspects of the invention, first longitudinal side can include a positive snap lock connection491for mating engagement with second longitudinal side492. Positive snap lock connections or snap lock connections are generally described in U.S. Pat. No. 7,131,242, incorporated herein by reference in its entirety. The entire length of tongue493can incorporate a positive snap lock or portions of tongue493can include a positive snap lock. Tongue493can include snap rivets. It will be appreciated that where tongue493includes a snap locking structure, an appropriate receiving structure is provided on the second longitudinal side having groove494. FIG.9illustrates an exemplary positive snap lock system, wherein male portion970includes collar972. Male portion970mechanically engages with receiving portion975with include recessed collar mount977. In use, male portion970is inserted into receiving portion975such that collar portion972engages recessed collar mount977, there by allowing insertion of the male portion970but preventing its release or withdrawal. Positive snap locking joints between staved portions of the offset staved pipe can be used to mechanically lock two staved portions together. The positive snap lock joints can be used alone or in combination with a resin or adhesive. In an aspect, a flexible resin is used in combination with the positive snap lock joint. FIG.10illustrates a cold water pipe451having an offset stave construction comprising multiple alternating first staves465and second staves467and further comprising a spirally wound ribbon497covering at least a portion of the outer surface of cold water pipe451. In aspects the ribbon is continuous from the bottom portion454of cold water pipe451to the top portion452of the cold water pipe451. In other aspects the ribbon497is provided only in those portions of pipe451that experience vortex shedding due to movement of water past the cold water pipe451. Ribbon497provides radial and longitudinal support to cold water pipe451. Ribbon497also prevents vibration along the cold water pipe and reduces vortex shedding due to ocean current action. Ribbon497can be the same thickness and width as an individual stave of cold water pipe451or can be two, three, four or more time the thickness and up to 10 times (e.g., 2, 3, 4, 5, 6, 7 8, 9 or 10 times) the width of an individual stave. Ribbon497can be mounted on the outside surface of the cold water pipe so as to lay substantially flat along the outside surface. In an embodiment, ribbon497can protrude outwardly from the outside surface of cold water pipe451so as to form a spirally wound strake. In aspects of the invention, a fin, blade or foil can be attached to various portions of ribbon or strake497. Such fins can form a helix wounding around a portion of the cold water pipe or winding the entire length of the cold water pipe. Fins can be angled and provide about the strake in any number to prevent vortex conditions caused by the cold water pipe. In some aspects the fins can protrude from the pipe surface a distance of between 1/32 and ⅓ of the pipe diameter (e/g, about 1/32 of the pipe diameter, about 1/16ththe pipe diameter, about ⅛ththe pipe diameter, about 1/7ththe pipe diameter, about ⅙ththe pipe diameter, about ⅕ththe pipe diameter, about ¼ the pipe diameter, and about ⅓rdthe pipe diameter). Ribbon497can be of any suitable material compatible with the material of the multiple staves forming cold water pipe451, including: polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), fiber reinforced plastic (FRP), reinforced polymer mortar (RPMP), polypropylene (PP), polyethylene (PE), cross-linked high-density polyethylene (PEX), polybutylene (PB), acrylonitrile butadiene styrene (ABS); polyurethane, polyester, fiber reinforced polyester, vinyl ester, reinforced vinyl ester, concrete, ceramic, or a composite of one or more thereof. Ribbon497can be molded, extruded, or pulltruded using standard manufacturing techniques. In one aspect, ribbon497is pulltruded to the desired shape and form and comprises a fiber or nylon reinforced vinyl ester similar to that used with the staves of cold water pipe451. Ribbon497can be joined to cold water pipe451using a suitable adhesive or resin including the resins of any of the materials above. In some aspects, ribbon497is not continuous along the length of cold water pipe451. In some aspects, ribbon497is not continuous about the circumference of cold water pipe451. In some aspects, ribbon497comprises vertical strips adhered to the outside surface of the cold water pipe451. In some aspects, where radial or other structural support is required, ribbon497can be a circumferential support member around the outside surface of the cold water pipe. Ribbon497can be adhesively bonded or adhered to the outside surface of the cold water pipe, using a suitable flexible adhesive. In an aspect, ribbon497can be mechanically coupled to the outside surface of cold water pipe451using multiple positive snap locks. With regard toFIG.11, an exemplary method of assembling a cold water pipe provides for the efficient transport and assembly of the cold water pipe451. Vertical cylindrical pipe sections are assembled by aligning1110alternating first and second stave portions to have the desired offset as described above. The first and second stave portions are then joined1120to form a cylindrical pipe section. The offset first and second staves can be joined using any of a variety of joining methods. In an aspect the multiple offset first and second stave portions are joined using a tongue and groove arrangement and a flexible adhesive. In an aspect the multiple first and second staved portions are joined using a mechanical positive snap lock. A combination of tongue and groove, snap lock mechanisms, and flexible adhesives can be used. After joining1120the multiple first and second stave portions to form a cylindrical pipe section having offset first and second stave portions, a retaining band, inflatable sleeve or other jig can be attached1122to the cylindrical pipe section to provide support and stability to the pipe section. The steps of aligning1110and joining1120multiple offset first and second stave portions can be repeated1124to form any number of prefabricated cylindrical pipe sections. It will be appreciated that the cylindrical pipe section can be prefabricated at the OTEC plant facility or remotely and then transported to the OTEC plant facility for additional construction to form the fully assembled cold water pipe451. Having assembled at least two cylindrical pipe sections having offset staves, an upper and lower cylindrical pipe sections are joined1126and the offset staves of each pipe section are aligned. A flexible adhesive can be applied1130to the butt joint of the offset staves of the upper and lower cylindrical pipe sections. The staves of the two pipe sections can be joined using a variety of end butt joints including biscuit joinery. In an aspect, the offset staves of the upper and lower cylindrical pipe portions can be provided with aligning joining voids which in turn can be filled with a flexible adhesive. Gaps in and joints between pipe sections or between and individual staves can be filled1132with additional flexible resin. Once the two pipe sections have been joined and the resin applied where needed the two pipe sections are allowed to cure1134. The retaining band is then removed1136from the lower pipe section and a spirally wound strake is attached thereto. The spirally wound strake can be attached using adhesive bonding, mechanical bonding, for example positive snap locks, or a combination of the adhesive and mechanical bonding. In an aspect of the method of assembly, after the spiral strake is attached to the lower pipe section, the entire pipe assembly can be shifted, for example lowered, so that the previous upper pipe portion becomes the new lower pipe portion,1138. Then a new upper cylindrical pipe section is assembled1140in a similar manner as described above. That is, first and second stave portions are aligned1142to achieve the desired offset. The first and second stave portions are then joined1144to form a new cylindrical pipe section, e.g., new upper pipe section. As previously mentioned, a retaining band, inflatable sleeve or other jig can be used to provide support and stability to the cylindrical pipe section during construction of the cold water pipe451. Having assembled new upper pipe section1144, the offset staves of the new lower pipe section and the new upper pipe section are aligned and drawn together1146. Adhesive or flexible resin is applied1148to the end butt joints as described above, for example in conjunction with biscuit joinery or with aligning joining voids. Any gaps between the new lower pipe section and the new upper pipe section or between any two stave portions can be filled1150with additional flexible resin. The entire assembly can then be left to cure1152. The retaining jig can be removed1154as before and the spiral strake can be attached to the new lower portion. And, as before, the entire pipe assembly can be shifted to provide for the next cylindrical pipe section. In this manner, the method can be repeated until the desired pipe length is achieved. It will be appreciated that joining cylindrical pipe sections having offset staves can be accomplished in a number of manners consistent with the present invention. The method of joining offset staves provides for a continuous pipe without the need for bulky, heavy or interfering joining hardware between the pipe segments. As such a continuous pipe having nearly uniform material properties, including flexibility and rigidity, is provided. Example A cold water pipe assembly is provided that facilitates on site construction of a continuous, offset staved pipe of approximately 3000 feet. Additionally the staved design accounts for adverse shipping and handling loads traditionally experienced by segmented pipe construction. For example towing and upending of traditionally constructed segmented cold water pipes imposes hazardous loads on the pipe. Staved construction allows offsite manufacturing of multiple staves of 40 to 50 ft lengths. Each stave is approximately 52 inches wide and 4 to 12 inches thick. The staves can be shipped in stacks or containers to the offshore platform and the cold water pipe can then be constructed on the platform from the multiple staves. This eliminates the need for a separate facility to assemble pipe sections. The stave portions can be constructed from a nylon reinforced vinyl ester having a modulus of elasticity of between about 66,000 psi and 165,000 psi. The stave portions can have an ultimate strength of between about 15,000 psi and 45,000 psi, with a tensile strength between about 15,000 psi to 45,000 psi. In an aspect, the stave portions can have a modulus of elasticity of 150,000 psi, an ultimate strength of 30,000 psi and a yield strength of 30,000 psi, such that the installed CWP behaves similar to a hose rather than a purely rigid pipe. This is advantageous in storm conditions as the pipe is more flexible and avoids cracking or breaking. In an aspect, the pipe can deflect approximately two diameters from center at the unconnected lower end. Deflection at the unconnected lower end should not be so great as to interfere with the mooring system of the OTEC power plant or any other underwater systems involved in plant operations. The cold water pipe connects to the bottom portion of the OTEC power plant. More specifically, the cold water pipe connects using a dynamic bearing with the bottom portion of the OTEC spar ofFIG.3. Cold water pipe connections in OTEC applications are described in Section 4.5 of Avery & Wu, “Renewable Energy from the Ocean, a Guide to OTEC,” Oxford University Press, 1994, incorporated herein by reference in its entirety. One of the significant advantages of using the spar buoy as the platform is that doing so results in relatively small rotations between the spar itself and the CWP even in the most severe 100-year storm conditions. In addition the vertical and lateral forces between the spar and the CWP are such that the downward force between the spherical ball and its seat keeps the bearing surfaces in contact at all times. Because this bearing that also acts as the water seal does not come out of contact with its mating spherical seat there is no need to install a mechanism to hold the CWP in place vertically. This helps to simplify the spherical bearing design and also minimizes the pressure losses that would otherwise be caused by any additional CWP pipe restraining structures or hardware. The lateral forces transferred through the spherical bearing are also low enough that they can be adequately accommodated without the need for vertical restraint of the CWP. Cold water is drawn through the cold water pipe via one or more cold water pumps such and flows via one or more cold water passages or conduits to the condenser portion of a multi-stage OTEC power plant. Further details of cold water pipe construction and performance are described in U.S. patent application Ser. No. 12/691,655, entitled “Ocean Thermal Energy Conversion Power Plant Cold Water Pipe,” filed on Jan. 21, 2010, the entire contents of which are incorporated herein by reference. Cold Water Pipe Connection The connection between the cold water pipe351and the spar platform311presents construction, maintenance and operational challenges. For example, the cold water pipe is a 2000 ft to 4000 ft vertical column suspended in the dynamic ocean environment. The platform or vessel to which the cold water pipe connects is also floating in the dynamic ocean environment. Moreover, the pipe is ideally connected below the waterline, and in some aspects, well below the waterline and close to the bottom of the vessel. Maneuvering the fully assembled pipe into the proper position and a securing the pipe to the vessel or platform is a difficult task. The cold water pipe connection supports the static weight of the pipe suspended from the platform and accounts for the dynamic forces between the platform and the suspended pipe due to wave action, pipe vibration, and pipe movement. Various OTEC cold water pipe connections, including gimbal, ball and socket, and universal connections, are disclosed in Section 4.5 of “Renewable Energy from the Ocean, a Guide to OTEC” William Avery and Chih Wu, Oxford University Press, 1994, incorporated herein by reference. Only the gimbal connection was operationally tested and included a two-axis gimbal allowing for 30° of rotation. As described in Avery and Wu, in the plane of the gimbal, a spherical shell formed the top of the pipe. A cylindrical cap with a flat ring of nylon and Teflon provided a sliding seal between the cold water in the pipe and the surrounding platform structure. The gimbaled pipe connection is illustrated inFIG.12. Previous cold water pipe connections were designed for traditional hull forms and platforms that exhibit greater vertical displacement due to heave and wave action than spar platforms. One of the significant advantages of using the spar buoy as the platform is that doing so results in relatively small rotations between the spar itself and the CWP even in the most severe 100-year storm conditions. In addition the vertical and lateral forces between the spar and the CWP are such that the downward force between the spherical ball and its seat keeps the bearing surfaces in contact at all times. In aspects, the downward force between the CWP and the connection bearing surface is between 0.4 g and 1.0 g. Because this bearing that also acts as the water seal does not come out of contact with its mating spherical seat there is no need to install a mechanism to hold the CWP in place vertically. This helps to simplify the spherical bearing design and also minimizes the pressure losses that would otherwise be caused by any additional CWP pipe restraining structures or hardware. The lateral forces transferred through the spherical bearing are also low enough that they can be adequately accommodated without the need for vertical restraint of the CWP. Aspects of the present invention allow for vertical insertion of the cold water pipe upwardly through the bottom of the platform. This is accomplished by lifting the fully assembled cold water pipe into position from below the platform. This facilitates simultaneous construction of the platform and pipe as well as providing for easy installation and removal of the cold water pipe for maintenance. Referring toFIG.3, cold water pipe351connects to the submerged portion311of spar platform310at cold water pipe connection375. In an aspect the cold water pipe connects using a dynamic bearing with the bottom portion of the OTEC spar ofFIG.3. In an aspect of the present invention a cold water pipe connection is provided comprising a pipe collar seated via a spherical surface to a movable detent. The movable detent is coupled to the base of the spar platform. Incorporating the movable detent allows for vertical insertion and removal of the cold water pipe into and from the cold water pipe receiving bay. FIG.13illustrates an exemplary aspect wherein cold water pipe connection375includes pipe receiving bay776comprising bay walls777and detent housings778. Receiving bay776further comprises receiving diameter780, which is defined by the length of the diameter between bay walls777. In aspects, the receiving diameter is larger than the outer collar diameter781of cold water pipe351. Cold water pipe connection375and the lower portion of spar311can include structural reinforcement and supports to bear the weight and dynamic forces imposed on and transferred to spar311by cold water pipe351once suspended. Referring toFIG.14, cold water pipe connection375includes detent housing778and movable detent840, which is mechanically coupled to the detent housing778to allow for movement of detent840from a first position to a second position. In a first position, movable detent840is housed within detent housing778such that the detent840does not protrude inwardly toward the center of the receiving bay776and remains outside of receiving diameter780. In the first position, the top end portion385of cold water pipe351can be inserted into the pipe receiving bay776without interference from the moveable detent840. In an alternate aspect, movable detent840can be housed in a first position such that no aspect of the movable detent840protrudes inwardly toward the center of receiving bay776past the outer collar diameter781. In a further aspect, movable detent840in a first position does not interfere with the vertical movement of cold water pipe351through receiving bay776. In a second position, movable detent840extends beyond detent housing778and protrudes inwardly toward the center of receiving bay776. In the second position, movable detent840extends inwardly past the outer collar diameter781. Movable detent840can be adjusted or moved from a first position to a second position using hydraulic actuators, pneumatic actuators, mechanical actuators, electrical actuators, electro-mechanical actuators, or a combination of the above. Movable detent840includes a partial spherical or arcuate bearing surface842. Arcuate bearing surface842is configured to provide a dynamic bearing to cold water pipe bearing collar848when movable detent840is in a second position. Cold water pipe bearing collar842includes collar bearing surface849. Arcuate bearing surface842and collar bearing surface849can be cooperatively seated to provide a dynamic bearing to support the suspended weight of cold water pipe351. Additionally, arcuate bearing surface842and collar bearing surface849are cooperatively seated to account for relative motion between the cold water pipe351and the platform310without unseating the cold water pipe351. Arcuate bearing surface842and collar bearing surface849are cooperatively seated to provide a dynamic seal so that relatively warm water cannot enter pipe receiving bay776and ultimately cold water intake350once the cold water pipe351is connected to the platform310via cold water pipe connection375. Once cold water pipe351is suspended, cold water is drawn through the cold water pipe via one or more cold water pumps and flows via one or more cold water passages or conduits to the condenser portion of a multi-stage OTEC power plant. Arcuate bearing surface842and collar bearing surface849can be treated with a coating such as a Teflon coating to prevent galvanic interaction between the two surfaces. It will be appreciated that any combination of a dynamic bearing surface and a movable detent or pinion to connect the cold water pipe to the floating platform are contemplated in the claims and the disclosure herein. For example, in aspects, the arcuate bearing surface can be positioned above the movable detent, the arcuate bearing surface can be positioned to the side of the movable detent, or even below the movable detent. In aspects, the movable detent can be integral to the bottom portion of the floating platform as described above. In other aspects the movable detent can be integral to the cold water pipe. FIG.15illustrates an exemplary method of attaching a cold water pipe to a floating platform, and more specifically an OTEC floating platform. The method includes rigging guide lines and downhauls from the platform to the fully assembled cold water pipe. The cold water pipe is then lowered below the platform and aligned to the proper position. The cold water pipe is then raised into the pipe receiving bay, the movable detents or pinions are extended and the pipe is seated on the arcuate bearing surface. More specifically, guiding cables are attached910to the fully assembled cold water pipe351. In an exemplary embodiment, the cold water pipe351can include one or more inflatable sleeves to provide buoyancy during construction, movement, and upending of the cold water pipe. After the guide wires are attached910to the cold water pipe, the one or more inflatable sleeves can be deflated915so that the cold water pipe is negatively buoyant. In an embodiment, the cold water pipe can also include a clump weight or other ballast system that can be partially or completely filled with water or other ballast material to provide negative buoyancy to the cold water pipe. The cold water pipe is then lowered920to a position below the cold water pipe connection375of the floating OTEC platform310. Ballast can again be adjusted. The guide wires are adjusted925to properly position the cold water pipe below the cold water pipe connection375and alignment can be checked and confirmed930via video, remote sensors and other means. The cold water pipe assembly is then raised935to a position such that the cold water pipe bearing collar848is above the movable detents840of the cold water pipe connection assembly. Raising the cold water pipe into the cold water pipe connection can be done using the guide wires, inflatable sleeves, detachable balloons or a combination of the same. After the cold water pipe is raised935into the cold water pipe connection, the movable detents are extended940to provide a dynamic bearing surface for the cold water pipe. The cold water pipe is then lowered by adjusting the guide wires, deflating the inflatable sleeves or detachable balloons, or by adjusting the clump weight or other ballast system. A combination of the same may also be used. It will be appreciated that guide wires, inflation lines, ballast lines and the like should remain unobstructed from each other during movement of the cold water pipe. Moreover, the movement of the cold water pipe should not interfere with the mooring system of the OTEC platform. In a further aspect of the invention, a static connection can be made between the cold water pipe and the spar structure. In such aspects, the dynamic forces between the pipe and spar can be accounted for by varying the flexibility of the pipe near the top portion of the pipe. By allowing for movement of the lower and middle portions of the cold water pipe, the need for a dynamic pipe connection is reduced or avoided entirely. Avoiding the need for a gimbaled connection removes costly moving parts and simplifies fabrication of both the lower spar portion and the cold water pipe Referring toFIG.16, cold water pipe1651is connected to the lower portion of spar1611without the use of the above described dynamic bearings.FIG.16illustrates the cold water pipe connected to the lower portion of the spar structure in both the displaced and non-displaced configurations. The upper portions of the cold water pipe1651—that is those portion at and adjacently below the point of connection and the lower portion of spar1611—are stiffened to provide a relatively inflexible top portion1651A of the cold water pipe. Below the inflexible top portion1651A, relatively flexible middle portion1651B is provided. Below the flexible middle portion1651B is a moderately flexible lower portion1651C, which can comprise the largest portion of the cold water pipe assembly. A clump weight or ballast system can be secured to the bottom or any other part of the moderately flexible lower portion1651C. As illustrated, the flexible middle portion1651B allows for deflection of the lower portions of the cold water pipe away from the line of suspension of the cold water pipe. The amount of deflection can be between 0.25 degrees and 30 degrees, depending on the length and diameter of the cold water pipe suspended from the spar1011. Referring toFIG.17, the static cold water pipe—spar connection is detailed. The lower portion of spar1611includes receiving bay1713for receiving top portion1651A of cold water pipe1651. Receiving bay1713include tapered portion1714and contact pads1715. Upper portion1651A of cold water pipe1651includes collar1755with tapered collar surface1756and lifting lugs1775. Cold water pipe1651is connected to spar1611by lifting and retention cables1777, which are secured to the cold water pipe at lifting lugs1775. Cables1777are attached to mechanical winches1779housed in the lower portion of Spar1611. In an exemplary method of connecting the cold water pipe to the spar platform, the fully fabricated cold water pipe is lowered to a point just below the spar platform. Lifting and retention cables1777are connected to lifting lugs1775by remotely operated vehicles. Tension is taken up in the cables using the aforementioned mechanical winches housed in the lower portion of spar1611. As the upper portion1651A of cold water pipe1651enters receiving bay1713, it is guided into proper position by tapered portion1714until a secure connection is made between tapered collar surface1756and contact pads1715. Upon proper placement and secure connection of the cold water pipe in the receiving bay, the cables1777are mechanically locked to prevent downward movement of the cold water pipe1651. Because water is flowing on the inside of the cold water pipe and surround the outside of the pipe, a pressure seal is not necessary at the interface between the cold water pipe and the spar structure. In some implementations the seal between the cold water pipe and the spar structure minimizes water passage across the seal. The upward force exerted on the connecting pad can be imparted by the lifting cables, the buoyancy of the cold water pipe, or a combination of both. It will be appreciated that the number of lifting cables1777and corresponding lifting lugs1775is dependent on the size, weight and buoyance of the cold water pipe1651. In some aspects, cold water pipe1651can be positively, neutrally, or negatively buoyant. The number of lifting cables1777and corresponding lifting lugs1775is also dependent on any ballasting associated with the cold water pipe as well as the weight and buoyancy of the clump weight attached to the cold water pipe. In aspects of the invention, 2, 3, 4, 5, 6, or more lifting and retention cables can be used. G33 In additional aspects of the invention, the lifting lugs1775can comprise pad eyes bolted directly to the top of the cold water pipe using known fastening and connecting techniques. For example, barrel sockets, hex socket, coddler pins and the like can be incorporated into the staved top portion of the cold water pipe. In other aspects, a lifting collar can be installed to the top portion of the cold water pipe, the lifting collar comprising collar connecting surface1756and lifting lugs1755. The lifting collar can be the same or different material as the cold water pipe. The lifting collar, when attached to the cold water pipe can increase the rigidity of the cold water pipe more than the rigidity associated with the upper portion1651A.FIG.18is an illustration of a lifting collar1775mounted to a staved cold water pipe1651. The lifting collar can be mechanically, chemically, or thermally bonded to the upper portion1651A of the cold water pipe. For example, the same bonding resin to connect individual stave members of the cold water pipe can be used to connect the lifting collar to the cold water pipe. Heat Exchange System FIGS.3,3A and19and20illustrate an implementation of the present invention wherein a plurality of multi-stage heat exchangers420are arranged about the periphery of OTEC spar410. Heat exchangers420can be evaporators or condensers used in an OTEC heat engine. The peripheral layout of heat exchanges can be utilized with evaporator portion344or condenser portion348of an OTEC spar platform. The peripheral arrangement can support any number of heat exchangers (e.g., 1 heat exchanger, between 2 and 8 heat exchangers, 8-16 heat exchanger, 16-32 heat exchangers, or 32 or more heat exchangers). One or more heat exchangers can be peripherally arranged on a single deck or on multiple decks (e.g., on 2, 3, 4, 5, or 6 or more decks) of the OTEC spar410. One or more heat exchangers can be peripherally offset between two or more decks such that no two heat exchangers are vertically aligned over one another. One or more heat exchangers can be peripherally arranged so that heat exchangers in one deck are vertically aligned with heat exchanges on another adjacent deck. Individual heat exchangers420can comprise a multi-stage heat exchange system (e.g., a 2, 3, 4, 5, or 6 or more heat exchange system). In an embodiment, individual heat exchangers420can be a cabinet heat exchanger constructed to provide minimal pressure loss in the warm sea water flow, cold sea water flow, and working fluid flow through the heat exchanger. Referring toFIG.21an embodiment of a cabinet heat exchanger520includes multiple heat exchange stages,521,522,523and524. In an implementation the stacked heat exchangers accommodate warm sea water flowing down through the cabinet, from first evaporator stage521, to second evaporator stage522, to third evaporator stage523to fourth evaporator stage524. In another embodiment of the stacked heat exchange cabinet, cold sea water flows up through the cabinet from first condenser stage531, to second condenser stage532, to third condenser stage533, to fourth condenser stage534. Working fluid flows through working fluid supply conduits538and working fluid discharge conduits539. In an embodiment, working fluid conduits538and539enter and exit each heat exchanger stage horizontally as compared to the vertical flow of the warm sea water or cold sea water. The vertical multi-stage heat exchange design of cabinet heat exchanger520facilitates an integrated vessel (e.g., spar) and heat exchanger design, removes the requirement for interconnecting piping between heat exchanger stages, and ensures that virtually all of the heat exchanger system pressure drop occurs over the heat transfer surface. In an aspect, the heat transfer surface can be optimized using surface shape, treatment and spacing. Material selection such as alloys of aluminum offer superior economic performance over traditional titanium base designs. The heat transfer surface can comprise 1000 Series, 3000 Series or 5000 Series Aluminum alloys. The heat transfer surface can comprise titanium and titanium alloys. It has been found that the multi-stage heat exchanger cabinet enables the maximum energy transfer to the working fluid from the sea water within the relatively low available temperature differential of the OTEC heat engine. The thermodynamic efficiency of any OTEC power plant is a function of how close the temperature of the working fluid approaches that of the sea water. The physics of the heat transfer dictate that the area required to transfer the energy increases as the temperature of the working fluid approaches that of the sea water. To offset the increase in surface area, increasing the velocity of the sea water can increase the heat transfer coefficient. But this greatly increases the power required for pumping, thereby increasing the parasitic electrical load on the OTEC plant. Referring toFIG.22A, a conventional OTEC cycle wherein the working fluid is boiled in a heat exchanger using warm surface sea water. The fluid properties in this conventional Rankine cycle are constrained by the boiling process that limits the leaving working fluid to approximately 3° F. below the leaving warm seawater temperature. In a similar fashion, the condensing side of the cycle is limited to being no close than 2° F. higher than the leaving cold seawater temperature. The total available temperature drop for the working fluid is approximately 12° F. (between 68° F. and 56° F.). It has been found that a cascading multi-stage OTEC cycle allows the working fluid temperatures to more closely match that of the sea water. This increase in temperature differential increases the amount of work that can be done by the turbines associated with the OTEC heat engine. Referring toFIG.22B, an aspect of a cascading multi-stage OTEC cycle uses multiple steps of boiling and condensing to expand the available working fluid temperature drop. Each step requires an independent heat exchanger, or a dedicated heat exchanger stage in the cabinet heat exchanger520ofFIG.5. The cascading multi-stage OTEC cycle ofFIG.6ballows for matching the output of the turbines with the expected pumping loads for the sea water and working fluid. This highly optimized design would require dedicated and customized turbines. Referring toFIG.22C, a hybrid yet still optimized cascading OTEC cycle is shown that facilitates the use of identical equipment (e.g., turbines, generators, pumps) while retaining the thermodynamic efficiencies or optimization of the true cascade arrangement ofFIG.22B. In the hybrid cascade cycle ofFIG.22C, the available temperature differential for the working fluid ranges from about 18° F. to about 22° F. This narrow range allows the turbines in the heat engine to have identical performance specifications, thereby lowering construction and operation costs. System performance and power output is greatly increased using the hybrid cascade cycle in an OTEC power plant. Table A compares the performance of the conventional cycle ofFIG.22Awith that of the hybrid cascading cycle ofFIG.22C. TABLE AEstimated Performance for 100 MW Net OutputFour Stage HybridConventional CycleCascade CycleWarm Sea4,800,000GPM3,800,000GPMWater FlowCold Sea3,520,000GPM2,280,000GPMWater FlowGross Heat163,000BTU/kWH110,500BTU/kWHRate Utilizing the four stage hybrid cascade heat exchange cycle reduces the amount of energy that needs to be transferred between the fluids. This in turn serves to reduce the amount of heat exchange surface that is required. The performance of heat exchangers is affected by the available temperature difference between the fluids as well as the heat transfer coefficient at the surfaces of the heat exchanger. The heat transfer coefficient generally varies with the velocity of the fluid across the heat transfer surfaces. Higher fluid velocities require higher pumping power, thereby reducing the net efficiency of the plant. A hybrid cascading multi-stage heat exchange system facilitates lower fluid velocities and greater plant efficiencies. The stacked hybrid cascade heat exchange design also facilitates lower pressure drops through the heat exchanger. And the vertical plant design facilitates lower pressure drop across the whole system. FIG.22Dillustrates the impact of heat exchanger pressure drop on the total OTEC plant generation to deliver 100 MW to a power grid. Minimizing pressure drop through the heat exchanger greatly enhances the OTEC power plant's performance. Pressure drop is reduced by providing an integrated vessel or platform-heat exchanger system, wherein the sea water conduits form structural members of the vessel and allow for sea water flow from one heat exchanger stage to another in series. An approximate straight line sea water flow, with minimal changes in direction from intake into the vessel, through the pump, through the heat exchange cabinets and in turn through each heat exchange stage in series, and ultimately discharging from the plant, allows for minimal pressure drop. Example Aspects of the present invention provide an integrated multi-stage OTEC power plant that will produce electricity using the temperature differential between the surface water and deep ocean water in tropical and subtropical regions. Aspects eliminate traditional piping runs for sea water by using the off-shore vessel's or platform's structure as a conduit or flow passage. Alternatively, the warm and cold sea water piping runs can use conduits or pipes of sufficient size and strength to provide vertical or other structural support to the vessel or platform. These integral sea water conduit sections or passages serve as structural members of the vessel, thereby reducing the requirements for additional steel. As part of the integral sea water passages, multi-stage cabinet heat exchangers provide multiple stages of working fluid evaporation without the need for external water nozzles or piping connections. The integrated multi-stage OTEC power plant allows the warm and cold sea water to flow in their natural directions. The warm sea water flows downward through the vessel as it is cooled before being discharged into a cooler zone of the ocean. In a similar fashion, the cold sea water from deep in the ocean flows upward through the vessel as it is warmed before discharging into a warmer zone of the ocean. This arrangement avoids the need for changes in sea water flow direction and associated pressure losses. The arrangement also reduces the pumping energy required. Multi-stage cabinet heat exchangers allow for the use of a hybrid cascade OTEC cycle. These stacks of heat exchangers comprise multiple heat exchanger stages or sections that have sea water passing through them in series to boil or condense the working fluid as appropriate. In the evaporator section the warm sea water passes through the first stage where it boils off some of the working fluid as the sea water is cooled. The warm sea water then flows down the stack into the next heat exchanger stage and boils off additional working fluid at a slightly lower pressure and temperature. This occurs sequentially through the entire stack. Each stage or section of the cabinet heat exchanger supplies working fluid vapor to a dedicated turbine that generates electrical power. Each of the evaporator stages has a corresponding condenser stage at the exhaust of the turbine. The cold sea water passes through the condenser stacks in a reverse order to the evaporators. Referring toFIG.23, an exemplary multi-stage OTEC heat engine710utilizing a hybrid cascading heat exchange cycles is provided. Warm sea water is pumped from a warm sea water intake (not shown) via warm water pump712, discharging from the pump at approximately 1,360,000 gpm and at a temperature of approximately 79° F. All or parts of the warm water conduit from the warm water intake to the warm water pump, and from the warm water pump to the stacked heat exchanger cabinet can form integral structural members of the vessel. From the warm water pump712, the warm sea water then enters first stage evaporator714where it boils a first working fluid. The warm water exits first stage evaporator714at a temperature of approximately 76.8° F. and flows down to the second stage evaporator715. The warm water enters second stage evaporator715at approximately 76.8° F. where it boils a second working fluid and exits the second stage evaporator715at a temperature of approximately 74.5°. The warm water flows down to the third stage evaporator716from the second stage evaporator715, entering at a temperature of approximately 74.5° F., where it boils a third working fluid. The warm water exits the third stage evaporator716at a temperature of approximately 72.3° F. The warm water then flows from the third stage evaporator716down to the fourth stage evaporator717, entering at a temperature of approximately 72.3° F., where it boils a fourth working fluid. The warm water exits the fourth stage evaporator717at a temperature of approximately 70.1° F. and then discharges from the vessel. Though not shown, the discharge can be directed to a thermal layer at an ocean depth of or approximately the same temperature as the discharge temperature of the warm sea water. Alternately, the portion of the power plant housing the multi-stage evaporator can be located at a depth within the structure so that the warm water is discharged to an appropriate ocean thermal layer. In aspects, the warm water conduit from the fourth stage evaporator to the warm water discharge of the vessel can comprise structural members of the vessel. Similarly, cold sea water is pumped from a cold sea water intake (not shown) via cold sea water pump722, discharging from the pump at approximately 855,003 gpm and at a temperature of approximately 40.0° F. The cold sea water is drawn from ocean depths of between approximately 2700 and 4200 ft, or more. The cold water conduit carrying cold sea water from the cold water intake of the vessel to the cold water pump, and from the cold water pump to the first stage condenser can comprise in its entirety or in part structural members of the vessel. From cold sea water pump722, the cold sea water enters a first stage condenser724, where it condenses the fourth working fluid from the fourth stage boiler717. The cold seawater exits the first stage condenser at a temperature of approximately 43.5° F. and flows up to the second stage condenser725. The cold sea water enters the second stage condenser725at approximately 43.5° F. where it condenses the third working fluid from third stage evaporator716. The cold sea water exits the second stage condenser725at a temperature approximately 46.9° F. and flows up to the third stage condenser. The cold sea water enters the third stage condenser726at a temperature of approximately 46.9° F. where it condenses the second working fluid from second stage evaporator715. The cold sea water exits the third stage condenser726at a temperature approximately 50.4° F. The cold sea water then flows up from the third stage condenser726to the fourth stage condenser727, entering at a temperature of approximately 50.4° F. In the fourth stage condenser, the cold sea water condenses the first working fluid from first stage evaporator714. The cold sea water then exits the fourth stage condenser at a temperature of approximately 54.0° F. and ultimately discharges from the vessel. The cold sea water discharge can be directed to a thermal layer at an ocean depth of or approximately the same temperature as the discharge temperature of the cold sea water. Alternately, the portion of the power plant housing the multi-stage condenser can be located at a depth within the structure so that the cold sea water is discharged to an appropriate ocean thermal layer. The first working fluid enters the first stage evaporator714at a temperature of 56.7° F. where it is heated to a vapor with a temperature of 74.7° F. The first working fluid then flows to first turbine731and then to the fourth stage condenser727where the first working fluid is condensed to a liquid with a temperature of approximately 56.5° F. The liquid first working fluid is then pumped via first working fluid pump741back to the first stage evaporator714. The second working fluid enters the second stage evaporator715at a temperature approximately 53.0° F. where it is heated to a vapor. The second working fluid exits the second stage evaporator715at a temperature approximately 72.4° F. The second working fluid then flow to a second turbine732and then to the third stage condenser726. The second working fluid exits the third stage condenser at a temperature approximately 53.0° F. and flows to working fluid pump742, which in turn pumps the second working fluid back to the second stage evaporator715. The third working fluid enters the third stage evaporator716at a temperature approximately 49.5° F. where it will be heated to a vapor and exit the third stage evaporator716at a temperature of approximately 70.2° F. The third working fluid then flows to third turbine733and then to the second stage condenser725where the third working fluid is condensed to a fluid at a temperature approximately 49.5° F. The third working fluid exits the second stage condenser725and is pumped back to the third stage evaporator716via third working fluid pump743. The fourth working fluid enters the fourth stage evaporator717at a temperature of approximately 46.0° F. where it will be heated to a vapor. The fourth working fluid exits the fourth stage evaporator717at a temperature approximately 68.0° F. and flow to a fourth turbine734. The fourth working fluid exits fourth turbine734and flows to the first stage condenser724where it is condensed to a liquid with a temperature approximately 46.0° F. The fourth working fluid exits the first stage condenser724and is pumped back to the fourth stage evaporator717via fourth working fluid pump744. The first turbine731and the fourth turbine734cooperatively drive a first generator751and form first turbo-generator pair761. First turbo-generator pair will produce approximately 25 MW of electric power. The second turbine732and the third turbine733cooperatively drive a second generator752and form second turbo-generator pair762. Second turbo-generator pair762will produce approximately 25 MW of electric power. The four stage hybrid cascade heat exchange cycle ofFIG.7allows the maximum amount of energy to be extracted from the relatively low temperature differential between the warm sea water and the cold sea water. Moreover, all heat exchangers can directly support turbo-generator pairs that produce electricity using the same component turbines and generators. It will be appreciated that multiple multi-stage hybrid cascading heat exchangers and turbo generator pairs can be incorporated into a vessel or platform design. Example An offshore OTEC spar platform includes four separate power modules, each generating about 25 MWe Net at the rated design condition. Each power module comprises four separate power cycles or cascading thermodynamic stages that operate at different pressure and temperature levels and pick up heat from the sea water system in four different stages. The four different stages operate in series. The approximate pressure and temperature levels of the four stages at the rated design conditions (Full Load-Summer Conditions) are: Turbine inletCondenserPressure/Temp.Pressure/Temp.(Psia)/(°F.)(Psia)/(° F.)1 Stage137.9/74.7100.2/56.52″ Stage132.5/72.493.7/533′ Stage127.3/70.287.6/49.54″ Stage122.4/6881.9/46 The working fluid is boiled in multiple evaporators by picking up heat from warm sea water (WSW). Saturated vapor is separated in a vapor separator and led to an ammonia turbine by STD schedule, seamless carbon steel pipe. The liquid condensed in the condenser is pumped back to the evaporator by 2×100% electric motor driven constant speed feed pumps. The turbines of cycle-1 and 4 drive a common electric generator. Similarly the turbines of cycle-2 and 3 drive another common generator. In an aspect there are two generators in each plant module and a total of 8 in the 100 MWe plant. The feed to the evaporators is controlled by feed control valves to maintain the level in the vapor separator. The condenser level is controlled by cycle fluid make up control valves. The feed pump minimum flow is ensured by recirculation lines led to the condenser through control valves regulated by the flow meter on the feed line. In operation the four (4) power cycles of the modules operate independently. Any of the cycles can be shutdown without hampering operation of the other cycles if needed, for example in case of a fault or for maintenance. But that will reduce the net power generation of the power module as a whole module. Aspects of the present invention require large volumes of seawater. There will be separate systems for handling cold and warm seawater, each with its pumping equipment, water ducts, piping, valves, heat exchangers, etc. Seawater is more corrosive than fresh water and all materials that may come in contact with it need to be selected carefully considering this. The materials of construction for the major components of the seawater systems will be:Large bore piping: Fiberglass Reinforced Plastic (FRP)Large seawater ducts & chambers: Epoxy-coated carbon steelLarge bore valves: Rubber lined butterfly typePump impellers: Suitable bronze alloy Unless controlled by suitable means, biological growths inside the seawater systems can cause significant loss of plant performance and can cause fouling of the heat transfer surfaces leading to lower outputs from the plant. This internal growth can also increase resistance to water flows causing greater pumping power requirements, lower system flows, etc. and even complete blockages of flow paths in more severe cases. The Cold Sea Water (“CSW”) system using water drawn in from deep ocean should have very little or no bio-fouling problems. Water in those depths does not receive much sunlight and lack oxygen, and so there are fewer living organisms in it. Some types of anaerobic bacteria may, however, be able to grow in it under some conditions. Shock chlorination will be used to combat bio-fouling. The Warm Sea Water (“WSW”) system handling warm seawater from near the surface will have to be protected from bio-fouling. It has been found that fouling rates are much lower in tropical open ocean waters suitable for OTEC operations than in coastal waters. As a result, chemical agents can be used to control bio-fouling in OTEC systems at very low doses that will be environmentally acceptable. Dosing of small amounts of chlorine has proved to be very effective in combating bio-fouling in seawater. Dosages of chlorine at the rate of about 70 ppb for one hour per day, is quite effective in preventing growth of marine organisms. This dosage rate is only 1/20th of the environmentally safe level stipulated by EPA. Other types of treatment (thermal shock, shock chlorination, other biocides, etc.) can be used from time to time in-between the regimes of the low dosage treatment to get rid of chlorine-resistant organisms. Necessary chlorine for dosing the seawater streams is generated on-board the plant ship by electrolysis of seawater. Electro-chlorination plants of this type are available commercially and have been used successfully to produce hypochlorite solution to be used for dosing. The electro-chlorination plant can operate continuously to fill-up storage tanks and contents of these tanks are used for the periodic dosing described above. All the seawater conduits avoid any dead pockets where sediments can deposit or organisms can settle to start a colony. Sluicing arrangements are provided from the low points of the water ducts to blow out the deposits that may get collected there. High points of the ducts and water chambers are vented to allow trapped gases to escape. The Cold Seawater (CSW) system will consist of a common deep water intake for the plant ship, and water pumping/distribution systems, the condensers with their associated water piping, and discharge ducts for returning the water back to the sea. The cold water intake pipe extends down to a depth of more than 2700 ft, (e.g., between 2700 ft to 4200 ft), where the sea water temperature is approximately a constant 40° F. Entrance to the pipe is protected by screens to stop large organisms from being sucked in to it. After entering the pipe, cold water flows up towards the sea surface and is delivered to a cold well chamber near the bottom of the vessel or spar. The CSW supply pumps, distribution ducts, condensers, etc. are located on the lowest level of the plant. The pumps take suction from the cross duct and send the cold water to the distribution duct system. 4×25% CSW supply pumps are provided for each module. Each pump is independently circuited with inlet valves so that they can be isolated and opened up for inspection, maintenance, etc. when required. The pumps are driven by high-efficiency electric motors. The cold seawater flows through the condensers of the cycles in series and then the CSW effluent is discharged back to the sea. CSW flows through the condenser heat exchangers of the four plant cycles in series in the required order. The condenser installations is arranged to allow them to be isolated and opened up for cleaning and maintenance when needed. The WSW system comprises underwater intake grills located below the sea surface, an intake plenum for conveying the incoming water to the pumps, water pumps, biocide dosing system to control fouling of the heat transfer surfaces, water straining system to prevent blockages by suspended materials, the evaporators with their associated water piping, and discharge ducts for returning the water back to the sea. Intake grills are provided in the outside wall of the plant modules to draw in warm water from near the sea surface. Face velocity at the intake grills is kept to less than 0.5 ft/sec. to minimize entrainment of marine organisms. These grills also prevent entry of large floating debris and their clear openings are based on the maximum size of solids that can pass through the pumps and heat exchangers safely. After passing through these grills, water enters the intake plenum located behind the grills and is routed to the suctions of the WSW supply pumps. The WSW pumps are located in two groups on opposite sides of the pump floor. Half of the pumps are located on each side with separate suction connections from the intake plenum for each group. This arrangement limits the maximum flow rate through any portion of the intake plenum to about 1/16th of the total flow and so reduces the friction losses in the intake system. Each of the pumps are provided with valves on inlet sides so that they can be isolated and opened up for inspection, maintenance, etc. when required. The pumps are driven by high-efficiency electric motors with variable frequency drives to match pump output to load. It is necessary to control bio-fouling of the WSW system and particularly its heat transfer surfaces, and suitable biocides will be dosed at the suction of the pumps for this. The warm water stream may need to be strained to remove the larger suspended particles that can block the narrow passages in the heat exchangers. Large automatic filters or ‘Debris Filters’ can be used for this if required. Suspended materials can be retained on screens and then removed by backwashing. The backwashing effluents carrying the suspended solids will be routed to the discharge stream of the plant to be returned to the ocean. The exact requirements for this will be decided during further development of the design after collection of more data regarding the seawater quality. The strained warm seawater (WSW) is distributed to the evaporator heat exchangers. WSW flows through the evaporators of the four plant cycles in series in the required order. WSW effluent from the last cycle is discharged at a depth of approximately 175 feet or more below the sea surface. It then sinks slowly to a depth where temperature (and therefore density) of the seawater will match that of the effluent. Though embodiments herein have described multi-stage heat exchanger in a floating offshore vessel or platform, drawing cold water via a continuous, offset staved cold water pipe, it will be appreciated that other embodiments are within the scope of the invention. For example, the cold water pipe can be connected to a shore facility. The continuous offset staved pipe can be used for other intake or discharge pipes having significant length to diameter ratios. The offset staved construction can be incorporated into pipe sections for use in traditional segmented pipe construction. The multi-stage heat exchanger and integrated flow passages can be incorporated into shore based facilities including shore based OTEC facilities. Moreover, the warm water can be warm fresh water, geo-thermally heated water, or industrial discharge water (e.g., discharged cooling water from a nuclear power plant or other industrial plant). The cold water can be cold fresh water. The OTEC system and components described herein can be used for electrical energy production or in other fields of use including: salt water desalination: water purification; deep water reclamation; aquaculture; the production of biomass or biofuels; and still other industries. All references mentioned herein are incorporated by reference in their entirety. Other embodiments are within the scope of the following claims. | 82,632 |
11859598 | DETAILED DESCRIPTION Embodiments of an SMA actuator are described herein that include a compact footprint and providing a high actuation height, for example movement in the positive z-axis direction (z-direction), referred to herein as the z-stroke. Embodiments of the SMA actuator include an SMA buckle actuator and an SMA bimorph actuator. The SMA actuator may be used in many applications including, but not limited to, a lens assembly as an autofocus actuator, a micro-fluidic pump, a sensor shift, optical image stabilization, optical zoom assembly, to mechanically strike two surfaces to create vibration sensations typically found in haptic feedback sensors and devices, and other systems where an actuator is used. For example, embodiments of an actuator described herein could be used as a haptic feedback actuator for use in cellphones or wearable devices configured to provide the user an alarm, notification, alert, touched area or pressed button response. Further, more than one SMA actuator could be used in a system to achieve a larger stroke. For various embodiments, the SMA actuator has a z-stroke that is greater than 0.4 millimeters. Further, the SMA actuator for various embodiments has a height in the z-direction of 2.2 millimeters or less, when the SMA actuator is in its initial, a de-actuated position. Various embodiments of the SMA actuator configured as an autofocus actuator in a lens assembly may have a footprint as small as 3 millimeters greater than the lens inner diameter (“ID”). According to various embodiments, the SMA actuator may have a footprint that is wider in one direction to accommodate components including, but not limited to, sensors, wires, traces, and connectors. According to some embodiments, the footprint of an SMA actuator is 0.5 millimeters greater in one direction, for example the length of the SMA actuator is 0.5 millimeters greater than the width. FIG.1aillustrates a lens assembly including an SMA actuator configured as a buckle actuator according to an embodiment.FIG.1billustrates an SMA actuator configured as a buckle actuator according to an embodiment. The buckle actuators102are coupled with a base101. As illustrated inFIG.1b, SMA wires100are attached to buckle actuators102such that when the SMA wires100are actuated and contract this causes the buckle actuators102to buckle, which results in at least the center portion104of each buckle actuator102to move in the z-stroke direction, for example the positive z-direction, as indicated by the arrows108. According to some embodiments, the SMA wires100are actuated when electrical current is supplied to one end of the wire through a wire retainer such as a crimp structure106. The current flows through the SMA wire100heating it due to the resistance inherent in the SMA material of which the SMA wire100is made. The other side of the SMA wire100has a wire retainer such as a crimp structure106that connects the SMA wire100to complete the circuit to ground. Heating of the SMA wire100to a sufficient temperature causes the unique material properties to change from martensite to austenite crystalline structure, which causes a length change in the wire. Changing the electrical current changes the temperature and therefore changes the length of the wire, which is used to actuate and de-actuate the actuator to control the movement of the actuator in at least the z-direction. One skilled in the art would understand that other techniques could be used to provide electrical current to an SMA wire. FIG.2illustrates an SMA actuator configured as an SMA bimorph actuator according to an embodiment. As illustrated inFIG.2, the SMA actuator includes bimorph actuators202coupled with a base204. The bimorph actuators202include an SMA ribbon206. The bimorph actuators202are configured to move at least the unfixed ends of the bimorph actuators202in the z-stroke direction208as the SMA ribbon206shrinks. FIG.3illustrates an exploded view of an autofocus assembly including an SMA actuator according to an embodiment. As illustrated, an SMA actuator302is configured as a buckle actuator according to embodiments described herein. The autofocus assembly also includes optical image stabilization (“OIS”)304, a lens carriage306configured to hold one or more optical lens using techniques including those known in the art, a return spring308, a vertical slide bearing310, and a guide cover312. The lens carriage306is configured to slide against the vertical slide bearing310as the SMA actuator302moves in the z-stroke direction, for example the positive z-direction, when the SMA wires are actuated and pull and buckle the buckle actuators302using techniques including those described herein. The return spring308is configured to apply a force in the opposite direction to the z-stroke direction on the lens carriage306using techniques including those known in the art. The return spring308is configured, according to various embodiments, to move the lens carriage306in the opposite direction of the z-stroke direction when the tension in the SMA wires is lowered as the SMA wire is de-actuated. When the tension in the SMA wires is lowered to the initial value, the lens carriage306moves to the lowest height in the z-stroke direction.FIG.4illustrates the autofocus assembly including an SMA wire actuator according to an embodiment illustrated inFIG.3. FIG.5illustrates an SMA wire actuator according to an embodiment including a sensor. For various embodiments, the sensor502is configured to measure the movement of the SMA actuator in the z-direction or the movement of a component that that SMA actuator is moving using techniques including those known in the art. The SMA actuator including one or more buckle actuators506configured to actuate using one or more SMA wires508similar to those described herein. For example, in the autofocus assembly described in reference toFIG.4, the sensor is configured to determine the amount of movement the lens carriage306moves in the z-direction504from an initial position using techniques including those known in the art. According to some embodiments, the sensor is a tunnel magneto resistance (“TMR”) sensor. FIG.6illustrates a top view and a side view of an SMA actuator602configured as a buckle actuator according to an embodiment fitted with a lens carriage604.FIG.7illustrates a side-view of a section of the SMA actuator602according to the embodiment illustrated inFIG.6. According to the embodiment illustrated inFIG.7, the SMA actuator602includes a slide base702. According to an embodiment, the slide base702is formed of metal, such as stainless steel, using techniques including those know in the art. However, one skilled in the art would understand that other materials could be used to form the slide base702. Further, the slide base702, according to some embodiments, has spring arms612coupled with the SMA actuator602. According to various embodiments, spring arms612are configured to serve two functions. The first function is to help push on an object, for example a lens carriage604, into a guide cover's vertical slide surface. For this example, the spring arms612preload the lens carriage604up against this surface ensuring that the lens will not tilt during actuation. For some embodiments, the vertical slide surfaces708are configured to mate with the guide cover. The second function of the spring arms612is to help pull the SMA actuator602back down, for example in the negative z-direction, after the SMA wires608move the SMA actuator602in the z-stroke direction, the positive z-direction. Thus, when the SMA wires608are actuated they contract to move the SMA actuator602in the z-stroke direction and the spring arms612are configured to move the SMA actuator602in the opposite direction of the z-stroke direction when the SMA wires608are de-actuated. The SMA actuator602also includes a buckle actuator710. For various embodiments, the buckle actuator710is formed of metal, such as stainless steel. Further, the buckle actuator710includes buckle arms610and one or more wire retainers606. According to the embodiment illustrated inFIGS.6and7, the buckle actuator710includes four wire retainers606. The four wire retainers606are each configured to receive an end of an SMA wire608and retain the end of the SMA wire608, such that the SMA wire608is affixed to the buckle actuator710. For various embodiments, the four wire retainers606are crimps that are configured to clamp down on a portion of the SMA wire608to affix the wire to the crimp. One skilled in the art would understand that an SMA wire608may be affixed to a wire retainer606using techniques known in the art including, but not limited to, adhesive, solder, and mechanically affixed. The smart memory alloy (“SMA”) wires608extend between a pair of wire retainers606such that the buckle arms610of the buckle actuator710are configured to move when the SMA wires608are actuated which results in the pair of wire retainers606being pulled closer together. According to various embodiments, the SMA wires608are electrically actuated to move and control the position of the buckle arms610when a current is applied to the SMA wire608. The SMA wire608is de-actuated when the electrical current is removed or below a threshold. This moves the pair or wire retainers606apart and the buckle arms610move in the opposite direction of that when the SMA wire608is actuated. According to various embodiments, the buckle arms610are configured to have an initial angle of 5 degrees with respect to the slide base702when the SMA wire is de-actuated in its initial position. And, at full stroke or when the SMA wire is fully actuated the buckle arms610are configured to have an angle of 10 to 12 degrees with respect to the slide base702according to various embodiments. According to the embodiment illustrated inFIGS.6and7, the SMA actuator602also includes slide bearings706configured between the slide base702and the wire retainers606. The slide bearings706are configured to minimize any friction between the slide base702and a buckle arm610and/or a wire retainer606. The slide bearings for some embodiments are affixed to the slide bearings706. According to various embodiments the slide bearings are formed of polyoxymethylene (“POM”). One skilled in the art would understand that other structures could be used to lower any friction between the buckle actuator and the base. According to various embodiments, the slide base702is configured to couple with an assembly base704such as an autofocus base for an autofocus assembly. The actuator base704, according to some embodiments, includes an etched shim. Such an etched shim may be used to provide clearance for wires and crimps when the SMA actuator602is part of an assembly, such as an autofocus assembly. FIG.8illustrates multiple views of an embodiment of a buckle actuator802with respect to an x-axis, a y-axis, and a z-axis. As oriented inFIG.8, the buckle arms804are configured to move in the z-axis when the SMA wires are actuated and de-actuated as described herein. According to the embodiment illustrated inFIG.8, the buckle arms804are coupled with each other through a center portion such as a hammock portion806. A hammock portion806, according to various embodiments, is configured to cradle a portion of an object that is acted upon by the buckle actuator, for example a lens carriage that is moved by the buckle actuator using techniques including those described herein. A hammock portion806is configured to provide lateral stiffness to the buckle actuator during actuation according to some embodiments. For other embodiments, a buckle actuator does not include a hammock portion806. According to these embodiments, the buckle arms are configured to act on an object to move it. For example, the buckle arms are configured to act directly on features of a lens carriage to push it upward. FIG.9illustrates an SMA actuator configured as an SMA bimorph actuator according to an embodiment. The SMA bimorph actuator includes bimorph actuators902including those described herein. According to the embodiment illustrated inFIG.9, one end906of each of bimorph actuators902is affixed to a base908. According to some embodiments, the one end906is welded to base908. However, one skilled in the art would understand other techniques could be used to affix the one end906to the base908.FIG.9also illustrates a lens carriage904arranged such that the bimorph actuators902are configured to curl in the z-direction when actuated and lift the carriage904in the z-direction. For some embodiments, a return spring is used to push the bimorph actuators902back to an initial position. A return spring may be configured as described herein to aide in pushing the bimorph actuator down to their initial, de-actuated positions. Because of the small footprint of the bimorph actuators, SMA actuators can be made that have a reduced footprint over current actuator technologies. FIG.10illustrates a cutaway view of an autofocus assembly including an SMA actuator according to an embodiment that includes a position sensor, such as a TMR sensor. The autofocus assembly1002includes a position sensor1004attached to a moving spring1006, and a magnet1008attached to a lens carriage1010of an autofocus assembly including an SMA actuator, such as those described herein. The position sensor1004is configured to determine the amount of movement the lens carriage1010moves in the z-direction1005from an initial position based on a distance that the magnet1008is from the position sensor1004using techniques including those known in the art. According to some embodiments, the position sensor1004is electrically coupled with a controller or a processor, such as a central processing unit, using a plurality of electrical traces on a spring arm of a moving spring1006of an optical image stabilization assembly. FIGS.11a-cillustrates views of bimorph actuators according to some embodiments. According to various embodiments, a bimorph actuator1102includes a beam1104and one or more SMA materials1106such as an SMA ribbon1106b(e.g., as illustrated in a perspective view of a bimorph actuator including an SMA ribbon according to the embodiment ofFIG.11b) or SMA wire1106a(e.g., as illustrated in a cross-section of a bimorph actuator including an SMA wire according to the embodiment ofFIG.11a). The SMA material1106is affixed to the beam1104using techniques including those describe herein. According to some embodiments, the SMA material1106is affixed to a beam1104using adhesive film material1108. Ends of the SMA material1106, for various embodiments, are electrically and mechanically coupled with contacts1110configured to supply current to the SMA material1106using techniques including those known in the art. The contacts1110(e.g., as illustrated inFIGS.11aand11b), according to various embodiments, are gold plated copper pads. According to embodiments, a bimorph actuator1102having a length of approximately 1 millimeter are configured to generate a large stroke and push forces of 50 millinewtons (“mN”) is used as part of a lens assembly, for example as illustrated inFIG.11c. According to some embodiments, the use of a bimorph actuator1102having a length greater than 1 millimeter will generate more stroke but less force that that having a length of 1 millimeter. For an embodiment, a bimorph actuator1102includes a 20 micrometer thick SMA material1106, a 20 micrometer thick insulator1112, such as a polyimide insulator, and a 30 micrometer thick stainless steel beam1104or base metal. Various embodiments include a second insulator1114disposed between a contact layer including the contacts1110and the SMA material1106. The second insulator1114is configured, according to some embodiments, to insulate the SMA material1106from portions of the contact layer not used as the contacts1110. For some embodiments, the second insulator1114is a covercoat layer, such a polyimide insulator. One skilled in the art would understand that other dimensions and materials could be used to meet desired design characteristics. FIG.12illustrates views of an embodiment of a bimorph actuator according to an embodiment. The embodiment as illustrated inFIG.12includes a center feed1204for applying power. Power is supplied at the center of the SMA material1202(wire or ribbon), such as that described herein. Ends of the SMA material1202are grounded to the beam1206or base metal as a return path at the end pads1203. The end pads1203are electrically isolated from the rest of the contact layer1214. According to embodiments, the close proximity of a beam1206or base metal to the SMA material1202, such as an SMA wire, along the entire length of the SMA material1202provides faster cooling of the wire when current is turned off, that is the bimorph actuator is de-actuated. The result is a faster wire deactivation and actuator response time. The thermal profile of the SMA wire or ribbon is improved. For example, the thermal profile is more uniform such that a higher total current can be reliably delivered to the wire. Without a uniform heat sink, portions of the wire, such as a center region, may overheated and be damaged thus requiring a reduced current and reduced motion to reliably operate. The center feed1204provides the benefits of quicker wire activation/actuation (faster heating) and reduced power consumption (lower resistance path length) of the SMA material1202for faster response time. This allows a faster actuator motion and capability to operate at a higher movement frequency. As illustrated inFIG.12, the beam1206includes a center metal1208that is isolated from the rest of the beam1206to form the center feed1204. An insulator1210, such as those described herein, is disposed over the beam1206. The insulator1210is configured to have one or more openings or vias1212to provide electrical access to the beam1206, for example to couple a ground section1214bof the contact layer, and to provide contact to the center metal1208to form the center feed1204. A contact layer1214, such as those described herein, includes a power section1214aand a ground section1214b, according to some embodiments, to provide actuation/control signals to the bimorph actuator by way of a power supply contact1216and a ground contact1218. A covercoat layer1220, such as those described herein, is disposed over the contact layer1214to electrically isolate the contact layer except at portions of the contact layer1214where electrical coupling is desired (e.g., one or more contacts). FIG.13illustrates an end pad cross-section of a bimorph actuator according to an embodiment as illustrated inFIG.12. As described above, the end pad1203electrically isolated from the rest of the contact layer1214by way of a gap1222formed between the end pad1203and the contact layer1214. The gap is formed, according to some embodiments, using etching techniques including those known in the art. The end pad1203includes a via section1224configured to electrically couple the end pad1203with the beam1206. The via section1224formed in a via1212formed in the insulator1210. The SMA material1202is electrically coupled to the end pad1213. The SMA material1202can be electrically coupled to the end pad1213using technique including, but not limited to, solder, resistance welding, laser welding, and direct plating. FIG.14illustrates a center feed cross-section of a bimorph actuator according to an embodiment as illustrated inFIG.12. The center feed1204is electrically coupled with to a power supply through the contract layer1214and electrically and thermally coupled with the center metal1208by way of a via section1226in the center feed1204formed in a via1212formed in the insulator1210. The actuators described herein could be used to form an actuator assembly that uses multiple buckle and or multiple bimorph actuators. According to an embodiment, the actuators may be stacked on top of each other in order to increase a stroke distance that can be achieved. FIG.15illustrates an exploded view of an SMA actuator including two buckle actuators according to an embodiment. Two buckle actuators1302,1304, according to embodiments described herein, are arranged with respect to each other to use their motion to oppose each other. For various embodiments, the two buckle actuators1302,1304are configured to move in an inverse relation to each other to position a lens carriage1306. For example, the first buckle actuator1302is configured to receive an inverse power signal of the power signal sent to the second buckle actuator1304. FIG.16illustrates an SMA actuator including two buckle actuators according to an embodiment. The buckle actuators1302,1304are configured such that the buckle arms1310,1312of each buckle actuator1302,1304face each other and the slide base1314,1316of each buckle actuator1302,1304are an outer surface of the two buckle actuators. A hammock portion1308of each SMA actuators1302,1304, according to various embodiments, is configured to cradle a portion of an object that is acted upon by the one or more buckle actuators1302,1304, for example a lens carriage1306that is moved by the buckle actuators using techniques including those described herein. FIG.17illustrates a side view of an SMA actuator including two buckle actuators according to an embodiment that illustrates the direction of the SMA wires1318that result in moving an object such as a lens carriage in a positive z direction or in an upwardly direction. FIG.18illustrates a side view of an SMA actuator including two buckle actuators according to an embodiment that illustrates the direction of the SMA wires1318that result in moving an object such as a lens carriage in a negative z direction or in an downwardly direction. FIG.19illustrates an exploded view an assembly including an SMA actuator including two buckle actuator according to an embodiment. The buckle actuators1902,1904are configured such that the buckle arms1910,1912of each buckle actuator1902,1904are an outer surface of the two buckle actuators and the slide base1914,1916of each buckle actuator1902,1904face each other. A hammock portion1908of each SMA actuators1902,1904, according to various embodiments, is configured to cradle a portion of an object that is acted upon by the one or more buckle actuators1902,1904, for example a lens carriage1906that is moved by the buckle actuators using techniques including those described herein. For some embodiments, the SMA actuator includes a base portion1918configured to receive the second buckle actuator1904. The SMA actuator may also include a cover portion1920.FIG.20illustrates an SMA actuator including two buckle actuators according to an embodiment including a base portion and a cover portion. FIG.21illustrates an SMA actuator including two buckle actuators according to an embodiment. For some embodiments, the buckle actuators1902,1904are arranged with respect to each other such that the hammock portions1908of the first buckle actuator1902are rotated about 90 degrees from the hammock portions of the second buckle actuator1904. The 90 degrees configuration enables pitch and roll rotation of an object, such as a lens carriage1906. This provides better control over the movement of the lens carriage1906. For various embodiments, differential power signals are applied to the SMA wires of each buckle actuator pair, which provides for pitch and roll rotation of the lens carriage for tilt OIS motion. Embodiments of the SMA actuators including two buckle actuators remove the need to have a return spring. The use of two buckler actuators can improve/reduce hysteresis when using SMA wire resistance for positional feedback. The opposing force SMA actuators including two buckler actuators aid in more accurate position control due to lower hysteresis than those including a return spring. For some embodiments, such as the embodiment illustrated inFIG.22, the SMA actuator including two buckle actuators2202,2204provide 2-axis tilt using differential power to the left and right SMA wires2218a,2218bof each buckle actuator2202,2204. For example, a left SMA wire2218ais actuated with higher power than a right SMA wire2218b. This causes the left side of the lens carriage2206to move down and right side to move up (tilt). The SMA wires of the first buckle actuator2202are held at equal power, for some embodiments, to act as a fulcrum for the SMA wires2218a,2218bto differentially push against to cause tilt motion. Reversing the power signals applied to the SMA wires, for example applying equal power to the SMA wires of the second buckle actuator2202and using differential power to the left and right SMA wires2218a,2218bof the second buckle actuator2204results in a tilt of the lens carriage2206in the other direction. This provides the ability to tilt an object, such as a lens carrier, in either axis of motion or can tune out any tilt between the lens and sensor for good dynamic tilt, which leads to better picture quality across all pixels. FIG.23illustrates a SMA actuator including two buckle actuators and a coupler according to an embodiment. The SMA actuator includes two buckle actuators such as those described herein. A first buckle actuator2302is configured to couple with a second buckle actuator2304using a coupler, such as a coupler ring2305. The buckle actuators2302,2304are arranged with respect to each other such that the hammock portions2308of the first buckle actuator2302are rotated about 90 degrees from the hammock portions2309of the second buckle actuator2304. A payload for moving, such as a lens or lens assembly, is attached to a lens carriage2306configured to be disposed on a slide base of first buckle actuator2302. For various embodiments, equal power can be applied to the SMA wires of the first buckle actuator2302and the second buckle actuator2304. This can result in maximizing the z stroke of the SMA actuator in the positive z-direction. For some embodiments, the stroke of the SMA actuator can have a z stroke equal to or greater than two times the stroke of other SMA actuators including two buckle actuators. For some embodiments, an additional spring can be added to for the two bucklers to push against to aid in pushing the actuator assembly and the payload back down when the power signals are removed from the SMA actuator. Equal and opposite power signals can be applied to the SMA wires of the first buckle actuator2302and the second buckle actuator2304. This enables the SMA actuator to be moved in the positive z-direction by a buckle actuator and to be moved in the negative z-direction by a buckle actuator, which enables accurate control of the position of the SMA actuator. Further, equal and opposite power signals (differential power signals) can be applied to the left and right SMA wire of the first buckle actuator2302and the second buckle actuator2304to tilt an object, such as a lens carriage2306in the direction of at least one of two axis. Embodiments of SMA actuator including the two buckle actuators and a coupler, such as that illustrated inFIG.23, can be coupled with an additional buckle actuator and pairs of buckle actuators to achieve a desired stroke greater than that of the single SMA actuator. FIG.24illustrates an exploded view of an SMA system including an SMA actuator including a buckle actuator with a laminate hammock according to an embodiment. As described herein, SMA systems, for some embodiments, are configured to be used in conjunction with one or more camera lens elements as an auto-focusing drive. As illustrated inFIG.24, the SMA system includes a return spring2403configured, according to various embodiments, to move a lens carriage2406in the opposite direction of the z-stroke direction when the tension in the SMA wires2408is lowered as the SMA wire is de-actuated. The SMA system for some embodiments includes a housing2409configured to receive the return spring2403and to act a slide bearing to guide the lens carriage in the z-stroke direction. The housing2409is also configured to be disposed on the buckle actuator2402. The buckle actuator2402includes a slide base2401similar to those described herein. The buckle actuator2402includes buckle arms2404coupled with a hammock portion, such as a laminated hammock2406formed of a laminate. The buckle actuator2402also includes a SMA wire attach structures such as a laminate formed crimp connection2412. As illustrated inFIG.24, the slide base2401is disposed on an optional adaptor plate2414. The adaptor plate is configured to mate the SMA system or the buckler actuator2402to another system, such as an OIS, additional SMA systems, or other components.FIG.25illustrates an SMA system2501including an SMA actuator including a buckle actuator2402with a laminate hammock according to an embodiment. FIG.26illustrates a buckle actuator including a laminate hammock according to an embodiment. The buckle actuator2402includes buckle arms2404. The buckle arms2404are configured to move in the z-axis when the SMA wires2412are actuated and de-actuated as described herein. The SMA wires2408are attached to the buckle actuator using laminate formed crimp connections2412. According to the embodiment illustrated inFIG.26, the buckle arms2404are coupled with each other through a center portion such as a laminate hammock2406. A laminate hammock2406, according to various embodiments, is configured to cradle a portion of an object that is acted upon by the buckle actuator, for example a lens carriage that is moved by the buckle actuator using techniques including those described herein. FIG.27illustrates a laminate hammock of an SMA actuator according to an embodiment. For some embodiments, the laminate hammock2406material is a low stiffness material so it does not resist the actuation motion. For example, the laminate hammock2406is formed using a copper layer disposed on a first polyimide layer with a second polyimide layer disposed on the copper. For some embodiments, the laminate hammock2406is formed on buckle arms2404using deposition and etching techniques including those known in the art. For other embodiments, the laminate hammock2406is formed separately from the buckle arms2404and attached to the buckle arms2404using techniques including welding, adhesive, and other techniques known in the art. For various embodiments, glue or other adhesive is used on the laminate hammock2406to ensure the buckler arms2404stay in a position relative to a lens carriage. FIG.28illustrates a laminate formed crimp connection of an SMA actuator according to an embodiment. The laminate formed crimp connection2412is configured to attach an SMA wire2408to the buckle actuator and to create an electrical circuit joint with the SMA wire2408. For various embodiments, the laminated formed crimp connection2412includes a laminate formed of one or more layers of an insulator and one or more layers of a conductive layer formed on a crimp. For example, a polyimide layer is disposed on at least a portion of the stainless steel portion forming a crimp2413. A conductive layer, such as copper, is then disposed on the polyimide layer, which is electrically coupled with one or more signal traces2415disposed on the buckle actuator. Deforming the crimp to come in to contact with the SMA wire therein also puts the SMA wire in electrical contact with the conductive layer. Thus, the conductive layer coupled with the one or more signal traces is used to apply power signals to the SMA wire using techniques including those described herein. For some embodiments, a second polyimide layer is formed over the conductive layer in areas where the conductive layer will not come into contact with the SMA wire. For some embodiments, the laminated formed crimp connection2412is formed on a crimp2413using deposition and etching techniques including those known in the art. For other embodiments, laminated formed crimp connection2412and the one or more electrical traces are formed separately from the crimp2413and the buckle actuator and attached to the crimp2412and the buckle actuator using techniques including welding, adhesive, and other techniques known in the art. FIG.29illustrates an SMA actuator including a buckle actuator with a laminate hammock. As illustrated inFIG.29, when a power signal is applied the SMA wire contracts or shortens to move the buckle arms and the laminate hammock in the positive z-direction. The laminate hammock that is in contact with an object in turn moves that object, such as a lens carriage in the positive z-direction. When the power signal is decreased or removed the SMA wire lengthens and moving the buckle arms and the laminate hammock in a negative z-direction. FIG.30illustrates an exploded view of an SMA system including an SMA actuator including a buckle actuator according to an embodiment. As described herein, SMA systems, for some embodiments, are configured to be used in conjunction with one or more camera lens elements as an auto-focusing drive. As illustrated inFIG.30, the SMA system includes a return spring3003configured, according to various embodiments, to move a lens carriage3005in the opposite direction of the z-stroke direction when the tension in the SMA wires3008is lowered as the SMA wire is de-actuated. The SMA system, for some embodiments, includes a stiffener3000disposed on the return spring3003. The SMA system for some embodiments includes a housing3009formed of two portions configured to receive the return spring3003and to act a slide bearing to guide the lens carriage in the z-stroke direction. The housing3009is also configured to be disposed on the buckle actuator3002. The buckle actuator3002includes a slide base3001similar to those described herein is formed of two portions. The slide base3001is split to electrically isolate the 2 sides (for example 1 side is ground, other side is power) because, according to some embodiments, current flows to the wire through the slide base3001portions. The buckle actuator3002includes buckle arms3004. Each pair of buckle actuators3002are formed on a separate portion of the buckle actuator3002. The buckle actuator3002also includes a SMA wire attach structures such as a resistance weld wire crimp3012. The SMA system optionally includes a flex circuit3020for electrically coupling the SMA wires3008to one or more control circuits. As illustrated inFIG.30, the slide base3001is disposed on an optional adaptor plate3014. The adaptor plate is configured to mate the SMA system or the buckler actuator3002to another system, such as an OIS, additional SMA systems, or other components.FIG.31illustrates an SMA system3101including an SMA actuator including a buckle actuator3002according to an embodiment. FIG.32including an SMA actuator including a buckle actuator according to an embodiment. The buckle actuator3002includes buckle arms3004. The buckle arms3004are configured to move in the z-axis when the SMA wires3012are actuated and de-actuated as described herein. The SMA wires2408are attached to the resistant weld wire crimps3012. According to the embodiment illustrated inFIG.32, the buckle arms3004are configured to mate with an object, such as a lens carriage, without a center portion using a two yoke capture joint. FIG.33illustrates a two yoke capture joint of a pair of buckle arms of an SMA actuator according to an embodiment.FIG.33also illustrates plating pads used to attached the optional flex circuit to the sliding base. For some embodiments, the plating pads are formed using gold.FIG.34illustrates a resistance weld crimp for an SMA actuator according to an embodiment used to attach an SMA wire to the buckle actuator. For some embodiments, glue or adhesive can also be placed on top of the weld to aid in mechanical strength and work as a fatigue strain relief during operation and shock loading. FIG.35illustrates an SMA actuator including a buckle actuator with a two yoke capture joint. As illustrated inFIG.35, when a power signal is applied the SMA wire contracts or shortens to move the buckle arms in the positive z-direction. The two yoke capture joint is in contact with an object in turn moves that object, such as a lens carriage in the positive z-direction. When the power signal is decreased or removed the SMA wire lengthens and moving the buckle arms in a negative z-direction. The yoke capture feature ensures buckle arms stay in correct position relative to the lens carriage. FIG.36illustrates a SMA bimorph liquid lens according to an embodiment. The SMA bimorph liquid lens3501includes a liquid lens subassembly3502, a housing3504, and a circuit with SMA actuators3506. For various embodiments, the SMA actuators include 4 bimorph actuators3508, such as embodiments described herein. The bimorph actuators3508are configured to push on a shaping ring3510located on a flexible membrane3512. The ring warps the membrane3512/liquid3514changing the light path through the membrane3512/liquid3514. A liquid contain ring3516is used to contain the liquid3514between the membrane3512and the lens3518. Equal force from Bimorph actuators changes the focus point of the image in the Z direction (normal to lens) which allows it to work as an auto focus. Differential force from Bimorph actuators3508can move light rays in the X,Y axes directions which allows it to work as an optical image stabilizer according to some embodiments. Both OIS and AF functions could be achieved at the same time with proper controls to each actuator. For some embodiments, a 3 actuators are used. The circuit with SMA actuators3506includes one or more contacts3520for control signals to actuate the SMA actuators. According to some embodiments including 4 SMA actuators the circuit with SMA actuators3506includes 4 power circuit control contact for each SMA actuator and a common return contact. FIG.37illustrates a perspective SMA bimorph liquid lens according to an embodiment.FIG.38illustrates a cross-section and a bottom view of SMA bimorph liquid lens according to an embodiment. FIG.39illustrates an SMA system including an SMA actuator3902with bimorph actuators according to an embodiment. The SMA actuator3902includes 4 bimorph actuators using techniques described herein. Two of the bimorph actuators are configured as positive z-stroke actuators3904and two are configured as negative z-stroke actuators3906as illustrated inFIG.40, which illustrates the SMA actuator3902with bimorph actuators according to an embodiment. The opposing actuators3906,3904are configured to control motion in both directions over the entire stroke range. This provides the ability to tune control code to compensate for tilt. For various embodiments, two SMA wires3908attached to top of component enable the positive z-stroke displacement. Two SMA wires attached to a bottom of component enable the negative z-stroke displacement. For some embodiments, each bimorph actuators are attached to an object, such as a lens carriage3910, using tabs to engage the object. The SMA system includes a top spring3912configured to provide stability of the lens carriage3910in axes perpendicular to the z-stroke axis, for example in the direction of the x axis and the y axis. Further, a top spacer3914is configured to be arranged between the top spring3912and the SMA actuator3902. A bottom spacer3916is arranged between the SMA actuator3902and a bottom spring3918. The bottom spring3918is configured to provide stability of the lens carriage3910in axes perpendicular to the z-stroke axis, for example in the direction of the x axis and the y axis. The bottom spring3918is configured to be disposed on a base3920, such as those described herein. FIG.41illustrates the length4102of a bimorph actuator4103and the location of a bonding pad4104for an SMA wire4206to extend the wire length beyond the bimorph actuator. Longer wire than bimorph actuator is used to increased stroke & force. Thus, the extension length4108of that the SMA wire4206beyond the bimorph actuator4103is used to set the stroke and force for the bimorph actuator4103. FIG.42illustrates an exploded view of an SMA system including a SMA bimorph actuator4202according to an embodiment. The SMA system, according to various embodiments, is configured to use separate metal materials and non-conductive adhesives to create one or more electrical circuits to power the SMA wires independently. Some embodiments have no AF size impact and include 4 bimorph actuators, such as those described herein. Two of the bimorph actuators are configured as positive z stroke actuators and two negative z stroke actuators.FIG.43illustrates an exploded view of a subsection of the SMA actuator according to an embodiment. The subsection includes a negative actuator signal connection4302, a base4304with bimorph actuators4306. The negative actuator signal connection4302includes a wire bond pad4308for connecting an SMA wire of a bimorph actuator4306using techniques including those described herein. The negative actuator signal connection4302is affixed to the base4304using an adhesive layer4310. The subsection also includes a positive actuator signal connection4314with a wire bond pad4316for connecting an SMA wire4312of a bimorph actuator4306using techniques including those described herein. The positive actuator signal connection4314is affixed to the base4304using an adhesive layer4318. Each of the base4304, the negative actuator signal connection4302, and the positive actuator signal connection4314are formed of metal, for example stainless steel. Connection pads4322on each of the base4304, the negative actuator signal connection4302, and the positive actuator signal connection4314are configured to electrically couple control signals and ground for actuating the bimorph actuator4306using techniques including those described herein. For some embodiments, the connection pads4322are gold plated.FIG.44illustrates a subsection of the SMA actuator according to an embodiment. For some embodiments, gold platted pads are formed on the stainless steel layer for solder bonding or other known electrical termination methods. Further, formed wire bond pads are used for signal joints to electrically couple the SMA wires for power signals. FIG.45illustrates a 5 axis sensor shift system according to an embodiment. The 5 axis sensor shift system is configured to move an object, such as an image senor in 5 axis relative to one or more lens. This includes X/Y/Z axis translation and pitch/roll tilt. Optionally the system is configured to use only 4 axis with X/Y axis translation and pitch/roll tilt together with a separate AF on top to do Z motion. Other embodiments include the 5 axis sensor shift system configured to move one or more lens relative to an image sensor. Static lens stack mounted on top cover and inserts inside the ID (not touching the orange moving carriage inside) for some embodiments. FIG.46illustrates an exploded view of a 5 axis sensor shift system according to an embodiment. The 5 axis sensor shift system includes 2 circuit components: a flexible sensor circuit4602, bimorph actuator circuit4604; and 8-12 bimorph actuators4606built on to the bimorph circuit component using techniques including those described herein. The 5 axis sensor shift system includes a moving carriage4608configured to hold one or more lenses and an outer housing4610. The bimorph actuator circuit4604includes, according to an embodiment, includes 8-12 SMA actuators such as those described herein. The SMA actuators are configured to move the moving carriage4608in 5 axis, such as in an x-direction, a y-direction, a z-direction, pitch, and roll similar to other 5 axis systems described herein. FIG.47illustrates an SMA actuator including bimorph actuators integrated into this circuit for all motion according to an embodiment. Embodiment of a SMA actuator can including 8-12 bimorph actuators4606. However, other embodiments could include more or less.FIG.48illustrates an SMA actuator4802including bimorph actuators integrated into this circuit for all motion according to an embodiment partially formed to fit inside a corresponding outer housing4804.FIG.49illustrates a cross section of a 5 axis sensor shift system according to an embodiment. FIG.50illustrates an SMA actuator5002according to an embodiment including bimorph actuators. The SMA actuator5002is configured to use 4 side mounted SMA bimorph actuators5004to move an image sensor, lens, or other various payloads in the x and y direction.FIG.51illustrates a top view of an SMA actuator including bimorph actuators that moved an image sensor, lens, or other various payloads in different x and y positions. FIG.52illustrates an SMA actuator including bimorph actuators5202according to an embodiment configured as a box bimorph autofocus. Four top and bottom mounted SMA bimorph actuators, such as those described herein, are configured to move together to create movement in the z-stroke direction for autofocus motion.FIG.53illustrates an SMA actuator including bimorph actuators according to an embodiment and which two top mounted bimorph actuators5302are configured to push down on one or more lens.FIG.54illustrates an SMA actuator including bimorph actuators according to an embodiment and which two bottom mounted bimorph actuators5402are configured to push up on one or more lens.FIG.55illustrates an SMA actuator including bimorph actuators according to an embodiment to show the four top and bottom mounted SMA bimorph actuators5502, such as those described herein, are used to move the one or more lens to create tilt motion. FIG.56illustrates a SMA system including a SMA actuator according to an embodiment including bimorph actuators configured as a two axis lens shift OIS. For some embodiments, the two axis lens shift OIS is configured to move a lens in the X/Y axis. For some embodiments, Z axis movement comes from a separate AF, such as those described herein. 4 bimorph actuators push on sides of auto focus for OIS motion.FIG.57illustrates an exploded view of SMA system including a SMA actuator5802according to an embodiment including bimorph actuators5806configured as a two axis lens shift OIS.FIG.58illustrates a cross-section of SMA system including a SMA actuator5802according to an embodiment including bimorph actuators5806configured as a two axis lens shift OIS.FIG.59illustrates box bimorph actuator5802according to an embodiment for use in a SMA system configured as a two axis lens shift OIS as manufactured before it is shaped to fit in the system. Such a system can be configured to have high OIS stroke OIS (e.g., +/−200 um or more). Further, such embodiments are configured to have a broad range of motion and good OIS dynamic tilt using 4 slide bearings, such as POM slide bearings. The embodiments are configured to integrate easily with AF designs (e.g., VCM or SMA). FIG.60illustrates a SMA system including a SMA actuator according to an embodiment including bimorph actuators configured as a five axis lens shift OIS and autofocus. For some embodiments, the five axis lens shift OIS and autofocus is configured to move a lens in the X/Y/Z axis. For some embodiments, pitch and yaw axis motion are for dynamic tilt tuning capability. 8 bimorph actuators are used to provide the motion for the auto focus and OIS using techniques described herein.FIG.61illustrates an exploded view of SMA system including a SMA actuator6202according to an embodiment including bimorph actuators6204according to an embodiment configured as a five axis lens shift OIS and autofocus.FIG.62illustrates a cross-section of SMA system including a SMA actuator6202according to an embodiment including bimorph actuators6204configured as a five axis lens shift OIS and autofocus.FIG.63illustrates box bimorph actuator6202according to an embodiment for use in a SMA system configured as a five axis lens shift OIS and autofocus as manufactured before it is shaped to fit in the system. Such a system can be configured to have high OIS stroke OIS (e.g., +/−200 um or more) and a high autofocus stroke (e.g., 400 um or more). Further, such embodiments enable to tune out any tilt and remove the need for a separate autofocus assembly. FIG.64illustrates a SMA system including a SMA actuator according to an embodiment including bimorph actuators configured as an outward pushing box. For some embodiments, the bimorph actuators assembly is configured to wrap around an object, such as a lens carriage. Since circuit assembly is moving with the lens carriage, a flexible portion for low X/Y/Z stiffness. Tail pads of the circuit are static. The outward pushing box can be configured for both 4 or 8 bimorph actuators. So, the outward pushing box can be configured as a 4 bimorph actuator on the sides for OIS with movement in X and Y axis. The outward pushing box can be configured as a 4 bimorph actuator on the top and bottom for autofocus with movement in z axis. The outward pushing box can be configured as an 8 bimorph actuator on the top, bottom, and sides for OIS and autofocus with movement in x, y, and z axis and capable of 3-axis tilt (pitch/roll/yaw).FIG.65illustrates an exploded view of a SMA system including a SMA actuator6602according to an embodiment including bimorph actuators6604configured as an outward pushing box. Thus, the SMA actuator is configured such that the bimorph actuators act on the outer housing6504to move the lens carriage6506using techniques described herein.FIG.66illustrates a SMA system including a SMA actuator6602according to an embodiment including bimorph actuators configured as an outward pushing box partially shaped to receive a lens carriage6604.FIG.67illustrates a SMA system including a SMA actuator6602including bimorph actuators6604according to an embodiment configured as an outward pushing box as manufactured before it is shaped to fit in the system. FIG.68illustrates a SMA system including a SMA actuator6802according to an embodiment including bimorph actuators configured as a three axis sensor shift OIS. For some embodiments, z axis movement comes from a separate autofocus system. 4 bimorph actuators configured to push on sides of a sensor carriage6804to provide the motion for the OIS using techniques described herein.FIG.69illustrates an exploded view of SMA including a SMA actuator6802according to an embodiment including bimorph actuators configured as a three axis sensor shift OIS.FIG.70illustrates a cross-section of SMA system including a SMA actuator6802according to an embodiment including bimorph actuators6806configured as a three axis sensor shift OIS.FIG.71illustrates a box bimorph actuator6802component according to an embodiment for use in a SMA system configured as a three axis sensor shift OIS as manufactured before it is shaped to fit in the system.FIG.72illustrates a flexible sensor circuit for use in a SMA system according to an embodiment configured as a three axis sensor shift OIS. Such a system can be configured to have high OIS stroke OIS (e.g., +/−200 um or more) and a high autofocus stroke (e.g., 400 um or more). Further, such embodiments are configured to have a broad range of two axis motion and good OIS dynamic tilt using 4 slide bearings, such as POM slide bearings. The embodiments are configured to integrate easily with AF designs (e.g., VCM or SMA). FIG.73illustrates a SMA system including a SMA actuator7302according to an embodiment including bimorph actuators7304configured as a six axis sensor shift OIS and autofocus. For some embodiments, the six axis sensor shift OIS and autofocus is configured to move a lens in the X/Y/Z/Pitch/Yaw/Roll axis. For some embodiments, pitch and yaw axis motion are for dynamic tilt tuning capability. 8 bimorph actuators are used to provide the motion for the auto focus and OIS using techniques described herein.FIG.74illustrates an exploded view of SMA system including a SMA actuator7402according to an embodiment including bimorph actuators7404configured as a six axis sensor shift OIS and autofocus.FIG.75illustrates a cross-section of SMA system including a SMA actuator7402according to an embodiment including bimorph actuators configured as a six axis sensor shift OIS and autofocus.FIG.76illustrates box bimorph actuator7402according to an embodiment for use in a SMA system configured as a six axis sensor shift OIS and autofocus as manufactured before it is shaped to fit in the system.FIG.77illustrates a flexible sensor circuit for use in a SMA system according to an embodiment configured as a three axis sensor shift OIS. Such a system can be configured to have high OIS stroke OIS (e.g., +/−200 um or more) and a high autofocus stroke (e.g., 400 um or more). Further, such embodiments enable to tune out any tilt and remove the need for a separate autofocus assembly. FIG.78illustrates a SMA system including a SMA actuator according to an embodiment including bimorph actuators configured as a two axis camera tilt OIS. For some embodiments, the two axis camera tilt OIS is configured to move a camera in the Pitch/Yaw axis. 4 bimorph actuators are used to push on top and bottom of autofocus for entire camera motion for the OIS pitch and yaw motion using techniques described herein.FIG.79illustrates an exploded view of SMA system including a SMA actuator7902according to an embodiment including bimorph actuators7904configured as two axis camera tilt OIS.FIG.80illustrates a cross-section of SMA system including a SMA actuator according to an embodiment including bimorph actuators configured as a two axis camera tilt OIS.FIG.81illustrates box bimorph actuator according to an embodiment for use in a SMA system configured as a two axis camera tilt OIS as manufactured before it is shaped to fit in the system.FIG.82illustrates a flexible sensor circuit for use in a SMA system according to an embodiment configured as a two axis camera tilt OIS. Such a system can be configured to have high OIS stroke OIS (e.g., plus/minus 3 degrees or more). The embodiments are configured to integrate easily with autofocus (“AF”) designs (e.g., VCM or SMA). FIG.83illustrates a SMA system including a SMA actuator according to an embodiment including bimorph actuators configured as a three axis camera tilt OIS. For some embodiments, the two axis camera tilt OIS is configured to move a camera in the Pitch/Yaw/Roll axis. 4 bimorph actuators are used to push on top and bottom of autofocus for entire camera motion for the OIS pitch and yaw motion using techniques described herein and 4 bimorph actuators are used to push on sides of autofocus for entire camera motion for the OIS roll motion using techniques described herein.FIG.84illustrates an exploded view of SMA system including a SMA actuator8402according to an embodiment including bimorph actuators8404configured as three axis camera tilt OIS.FIG.85illustrates a cross-section of SMA system including a SMA actuator according to an embodiment including bimorph actuators configured as a three axis camera tilt OIS.FIG.86illustrates box bimorph actuator for use in a SMA system according to an embodiment configured as a three axis camera tilt OIS as manufactured before it is shaped to fit in the system.FIG.87illustrates a flexible sensor circuit for use in a SMA system according to an embodiment configured as a three axis camera tilt OIS. Such a system can be configured to have high OIS stroke OIS (e.g., plus/minus 3 degrees or more). The embodiments are configured to integrate easily with AF designs (e.g., VCM or SMA). FIG.88illustrates exemplary dimensions for a bimorph actuator of an SMA actuator according to embodiments. The dimensions are preferred embodiments but one skilled in the art would understand that other dimensions could be used based on desired characteristics for an SMA actuator. FIG.89illustrates a lens system for a folded camera according to an embodiment. The folded camera includes a folding lens8902configured to bend light to a lens system8901including one or more lens8903a-d. For some embodiments, the folding lens is one or more of any of a prism and lens. The lens system8901is configured to have a principal axis8904that is at an angel to a transmission axis8906that is parallel to the direction of travel of the light prior to the light reaching the folding lens8902. For example, a folded camera is used in a camera phone system to reduce the height of a lens system8901in the direction of a transmission axis8906. Embodiments of the lens system include one or more liquid lens, such as those described herein. The embodiment illustrated inFIG.89includes two liquid lenses8903b,d, such as those described herein. The one or more liquid lens8903b,dare configured to be actuated using techniques including those describe herein. A liquid lens is actuated using actuators, including but not limited to, buckler actuators, bimorph actuators, and other SMA actuators.FIG.108illustrates a liquid lens actuated using buckler actuators60according to an embodiment. The liquid lens includes a shaping ring coupler64, a liquid lens assembly61, one or more buckler actuators60, such as those described herein, a slide base65, and a base62. The one or more buckler actuators60are configured to move the shaping ring/coupler64to change the shape of a flexible membrane of the liquid lens assembly61to move or shape the light rays, for example as described herein. For some embodiments, 3 or 4 actuators are used. A liquid lens can be configured alone or in combination with other lenses to act as an auto focus or optical image stabilizer. A liquid lens can also be configured to otherwise direct an image onto an image sensor. FIG.90illustrates several embodiments of a lens systems9001including liquid lenses9002a-hto focus an image on an image sensor9004. As illustrated, the liquid lens9002a-hmay include any lens shape and be configured to be dynamically configured to adjust the light path through the lens using techniques including those describe herein. A lens system for a folded camera is configured to include an actuated folding lens9100. An example of an actuated folding lens is a prism tilt, such as that illustrated inFIG.91. In the example illustrated inFIG.91, the folding lens is a prism9102disposed on an actuator9104. The actuator includes, but is not limited to, an SMA actuator including those described herein. For some embodiments, the prism tilt is disposed on an SMA actuator including 4 bimorph actuators9106, such as those described herein. The actuated folding lens9100, according to some embodiments, is configured as an optical image stabilizer using techniques including those described herein. For example, an actuated folding lens is configured to include an SMA system such as that illustrated inFIG.39. Another example of an actuated folding lens can include an SMA actuator such as that illustrated inFIG.21. However, the folding lens may also include other actuators. FIG.92illustrates a bimorph arm with an offset according to an embodiment. The bimorph arm9201includes a bimorph beam9202having a formed offset9203. The formed offset9203increases the mechanical advantage to generate a higher force than a bimorph arm without an offset. According to some embodiments, the depth of the offset9204(also referred herein as bend plane z offset9204) and the length of the offset9206(also referred herein as trough width9206) are configured to define characteristics of the bimorph arm, such as the peak force. For example, the graph inFIG.106illustrates the relationship between the bend plane z offset9204, the trough width9206, and the peak force of a bimorph beam9202according to an embodiment. The bimorph arm includes one or more SMA materials such as an SMA ribbon or SMA wire9210, such as those described herein. The SMA material is affixed to the beam using techniques including those describe herein. For some embodiments, the SMA material, such as an SMA wire9210, is affixed to a fixed end9212of the bimorph arm and to a load point end9214of the bimorph arm so that the formed offset9203is between both ends where the SMA material is affixed. Ends of the SMA material, for various embodiments, are electrically and mechanically coupled with contacts configured to supply current to the SMA material using techniques including those known in the art. The bimorph arm with an offset can be included in SMA actuators and systems such as those described herein. FIG.93illustrates a bimorph arm with an offset and a limiter according to an embodiment. The bimorph arm9301includes a bimorph beam9302having a formed offset9303and a limiter9304adjacent to the formed offset9303. The offset9303increases the mechanical advantage to generate a higher force than a bimorph arm9301without an offset and the limiter9304prevents motion of the arm in direction away from the unfixed, load point end9306of the bimorph actuator. The bimorph arm9301with a formed offset9303and limiter9304can be included in SMA actuators and systems such as those described herein. The bimorph arm9301includes one or more SMA materials such as an SMA ribbon or SMA wire9308, such as those described herein affixed to the bimorph arm9301using techniques including those described herein. FIG.94illustrates a bimorph arm with an offset and a limiter according to an embodiment. The bimorph arm9401includes a bimorph beam9402having a formed offset9403and a limiter9404adjacent to the formed offset9403. The limiter9404is formed as part of a base9406for the bimorph arm9401. The base9406is configured to receive a bimorph arm9401and includes a recess9408configured to receive the offset portion of the bimorph beam. The bottom of the recess configured as a limiter9404to be adjacent to the formed offset9403. The base9406may also include one or more portions9410configured to support portions of the bimorph arm when it is not actuated. The bimorph arm9401with a formed offset9403and limiter9404can be included in SMA actuators and systems such as those described herein. The bimorph arm9401includes one or more SMA materials such as an SMA ribbon or SMA wire, such as those described herein affixed to the bimorph arm9401using techniques including those described herein. FIG.95illustrates an embodiment of a base including a bimorph arm with an offset according to an embodiment. The bimorph arm9501includes a bimorph beam9502having a formed offset9504. The bimorph arm could also include a limiter using techniques including those described herein. The bimorph arm9501includes one or more SMA materials such as an SMA ribbon or SMA wire9506, such as those described herein affixed to the bimorph arm9501using techniques including those described herein. FIG.96illustrates an embodiment of a base9608including two bimorph arms with an offset according to an embodiment. Each bimorph arm9601a,bincludes a bimorph beam9602a,bhaving a formed offset9604a,b. Each bimorph arm9601a,bincludes one or more SMA materials such as an SMA ribbon or SMA wire9606a,b, such as those described herein affixed to the bimorph arm9501using techniques including those described herein. Each bimorph arm9601a,bcould also include a limiter using techniques including those described herein. Some embodiments include a base including more than two bimorph arms formed using techniques including those described herein. According to some embodiments, the bimorph arms9601are integrally formed with the base9608. For other embodiments, one or more of the bimorph arms9602a,bformed separately from the base9608and affixed to the base9608, using techniques including, but not limited to, solder, resistance welding, laser welding, and adhesive. For some embodiments, two or more bimorph arms9601a,bare configured to act on a single object. This enables the ability to increase the force applied to an object. The following graph inFIG.107illustrates examples of how a box volume which is an approximation of a box that encompasses the entire bimorph actuator is related to the work per bimorph component. The box volume is approximated using a length of the bimorph actuator9612, a width of the bimorph actuator9610, and height of bimorph actuator9614(referred collectively as “Box Volume”). FIG.97illustrates a buckler arm including load point extensions according to an embodiment. The buckler arm9701includes a beam portion9702and one or more load point extensions9704a,bextending from the beam portion9702. Each end9706a,bof the buckler arm9701is configured to be affixed to or integrally formed to a plate or other base using techniques including those described herein. The one or more load point extensions9704a,b, according to some embodiments, are affixed or integrally formed with the beam portion9702at an offset from a load point9710a,bof the beam portion9702. The load point9710a,bis the portion of the beam portion9702that is configured to transfer the force of the buckler arm9701to another object. For some embodiments, the load point9710a,bis the center of the beam portion9702. For other embodiments, the load point9710a,bis at a position other than the center of the beam portion9702. A load point extension9704a,bis configured to extend from the point it is joined to the beam portion9702toward the load point9710a,bof the beam portion9702in the direction of the longitudinal axis of the beam portion9702. For some embodiments, the end of the load point extension9704a,bextends to at least the load point9710a,bof the beam portion9702. The buckler arm9701includes one or more SMA materials such as an SMA ribbon or SMA wire9712, such as those described herein. The SMA material, such as an SMA wire9712, is affixed at opposing ends of the beam portion9702. The SMA material is affixed to opposing ends of the beam portion using techniques including those described herein. For some embodiments, the length of the load point extensions9704a,bcan be configured to any length contained within the longitudinal length of the associated flat (un-actuated) beam portion9702of the buckler arm9701. FIG.98illustrates a buckler arm9801including load point extensions9810according to an embodiment in an actuated position. The SMA material affixed to opposing ends of the beam portion9802is actuated using techniques including those described herein. The load point9804enables the buckler arm9801to increase the stroke range over buckler arms without the extensions. Thus, buckler arms including load point extensions enable a greater maximum vertical stroke. The buckler arm with load point extensions can be included in SMA actuators and systems such as those described herein. FIG.99illustrates a bimorph arm including load point extensions according to an embodiment. The bimorph arm9901includes a beam portion9902and one or more load point extensions9904a,bextending from the beam portion. One end of the bimorph arm9901is configured to be affixed to or integrally formed to a plate or other base using techniques including those described herein. The end of the beam portion9902opposite the affixed or integrally formed end is not fixed and is free to move. The one or more load point extensions9904a,b, according to some embodiments, are affixed or integrally formed with the beam portion9902at an offset from the free end of the beam portion9902. The load point extension9904a,bis configured to extend from the point it is joined to the beam portion9902in a direction away from a plane including the longitudinal axis of the beam portion9902. For example, the one or more load point extensions9904a,bextend in the direction that the free end of the beam portion extends when actuated. Some embodiments of a bimorph arm9901include one or more load point extensions9904a,bhaving a longitudinal axis that forms an angle including 1 degree to 90 degrees with a plane including the longitudinal axis of the beam portion. For some embodiments, the end9910a,bof the load point extension9904a,bis configured to engage an object configured to be moved. The bimorph arm9901includes one or more SMA materials such as an SMA ribbon or SMA wire9906, such as those described herein. The SMA material, such as an SMA wire9906, is affixed at opposing ends of the beam portion9902. The SMA material is affixed to opposing ends of the beam portion9902using techniques including those described herein. For some embodiments, the length of the load point extensions9904a,bcan be configured to any length. The location of the point of engagement of an object by an end9910a,bof the load point extension9904a,b, according to some embodiments, can be configured to be at any point along the longitudinal length of the beam portion9902. The height above the beam portion of the end of a load point extension when the beam portion is flat (un-actuated) can be configured to be any height. For some embodiments, the load point extension can be configured to be at least above other portions of the bimorph arm when the bimorph arm is actuated. FIG.100illustrates a bimorph arm including load point extensions according to an embodiment in an actuated position. The SMA material affixed to opposing ends of the beam portion2is actuated using techniques including those described herein. The load point extensions10enable the bimorph arm1to increase the stroke force over bimorph arms without the extensions. Thus, bimorph arms1including load point extensions10enable a greater force applied by the bimorph arm1. The bimorph arm1with load point extensions10can be included in SMA actuators and systems such as those described herein. FIG.101illustrates an SMA optical image stabilizer according to an embodiment. The SMA optical image stabilizer20includes a moving plate22and a static plate24. The moving plate22includes spring arms26integrally formed with the moving plate22. For some embodiments, the moving plate22and the static plate24are each formed to be a unitary, one-piece plate. The moving plate22includes a first SMA material attach portion28aand a second SMA material attach portion28b. The static plate24includes a first SMA material attach portion30aand a second SMA material attach portion30b. Each SMA material attach portion28,30is configured to fix an SMA material, such as an SMA wire, to a plate using resistance weld joints. The first SMA material attach portion28aof the moving plate22includes a first SMA wire32adisposed between it and a first SMA material attach portion30aof the static plate and a second SMA wire32bdisposed between it and the second SMA attach portion30bof the static plate24. The second SMA material attach portion28bof the moving plate22includes a third SMA wire32cdisposed between it and a second SMA material attach portion30bof the static plate and a fourth SMA wire32ddisposed between it and the first SMA attach portion30aof the static plate24. Actuating each SMA wire, using techniques including those described herein move the moving plate22away from the static plate24.FIG.102illustrates an SMA material attach portion40of a moving portion according to an embodiment. The SMA material attached portion is configured to have SMA material, such as an SMA wire41, resistance welded to the SMA material attach portion40.FIG.103illustrates an SMA attach portion42of a static plate with resistance welded SMA wires43attached thereto according to an embodiment. FIG.104illustrates an SMA actuator45including a buckle actuator according to an embodiment. The buckle actuator46includes buckle arms47, such as those describe herein. The buckle arms47are configured to move in the z-axis when the SMA wires48are actuated and de-actuated using techniques including those described herein. Each SMA wire48is attached to a respective resistance weld wire crimps49using resistance welding. Each resistance weld wire crimp49includes an island50isolated from the metal51forming the buckle arms47on at least one side of the SMA wire48. The island structure can be used in other actuators, optical image stabilizer, and auto focus systems to connect at least one side of an SMA wire to an isolated island structure formed in the base metal layer, such as the OIS application shown inFIG.101. FIG.105illustrates a resistance weld crimp including an island for an SMA actuator according to an embodiment used to attach an SMA wire48to a buckle actuator46using techniques including those describe here.FIG.105aillustrates a bottom portion of the SMA actuator45. The SMA actuator45, according to some embodiments, is formed from a stainless steel base layer51. A dielectric layer52, such as a polyimide layer, is disposed on the bottom portion of the stainless steel base layer51. A conductor layer53, according to some embodiments, is electrically connected to the stainless steel island50through a via in the dielectric layer52enabling an electrical connection to be made between the wire welded to the stainless steel island50and the conductor circuit attached to the stainless steel island. An island50, according to some embodiments, is etch from the stainless steel base layer. The dielectric layer52maintains the position of the island50within the stainless steel base layer51. The island50is configured to attached an SMA wire thereto using techniques including those described herein, such as resistance welding.FIG.105billustrates a top portion of the SMA actuator45including an island50. For some embodiments, glue or adhesive can also be placed on top of the weld to aid in mechanical strength and work as a fatigue strain relief during operation and shock loading. FIG.108includes a lens system including an SMA actuator with buckle actuators according to an embodiment. The lens system includes a liquid lens assembly61disposed on a base62. The lens system also includes a shaping ring/coupler64that is mechanically coupled with the buckle actuators60. The SMA actuator including the buckle actuators60, such as those described herein, is disposed a slide base65which is disposed on the base62. The SMA actuator is configured to move the shaping ring/coupler64along the optical axis of the liquid lens assembly61by actuating the buckle actuators60using techniques including those described herein. This moves the shaping ring/couple64to change the focus of the liquid lens in the liquid lens assembly. FIG.109illustrates an unfixed, load point end of a bimorph arm according to an embodiment. The unfixed, load point end70of a bimorph arm includes a flat surface71to affix SMA material, such as an SMA wire72. The SMA wire72is affixed to the flat surface71by a resistance weld73. The resistance weld73is formed using techniques including those known in the art. FIG.110illustrates an unfixed, load point end of a bimorph arm according to an embodiment. The unfixed, load point end76of a bimorph arm includes a flat surface77to affix SMA material, such as an SMA wire78. The SMA wire78is affixed to the flat surface77by a resistance weld, similar to that illustrated inFIG.109. An adhesive79is disposed on the resistance weld. This enables a more reliable joint between the SMA wire78and the unfixed, load point end76. The adhesive79includes, but is not limited to, conductive adhesive, non-conductive adhesive, and other adhesives known in the art. FIG.111illustrates an unfixed, load point end of a bimorph arm according to an embodiment. The unfixed, load point end80of a bimorph arm includes a flat surface81to affix SMA material, such as an SMA wire82. A metallic interlayer84is disposed on the flat surface81. The metallic interlayer84includes, but is not limited to, a gold layer, a nickel layer, or alloy layer. The SMA wire82is affixed to the metallic interlayer84disposed on the flat surface81by a resistance weld83. The resistance weld83is formed using techniques including those known in the art. The metallic interlayer84enables better adhesion with the unfixed, load point end80. FIG.112illustrates an unfixed, load point end of a bimorph arm according to an embodiment. The unfixed, load point end88of a bimorph arm includes a flat surface89to affix SMA material, such as an SMA wire90. A metallic interlayer92is disposed on the flat surface89. The metallic interlayer92includes, but is not limited to, a gold layer, a nickel layer, or alloy layer. The SMA wire90is affixed to the flat surface89by a resistance weld, similar to that illustrated inFIG.111. An adhesive91is disposed on the resistance weld. This enables a more reliable joint between the SMA wire90and the unfixed, load point end88. The adhesive91includes, but is not limited to, conductive adhesive, non-conductive adhesive, and other adhesives known in the art. FIG.113illustrates a fixed end of a bimorph arm according to an embodiment. The fixed end95of a bimorph arm includes a flat surface96to affix SMA material, such as an SMA wire97. The SMA wire97is affixed to the flat surface96by a resistance weld98. The resistance weld98is formed using techniques including those known in the art. FIG.114illustrates a fixed end of a bimorph arm according to an embodiment. The fixed end120of a bimorph arm includes a flat surface121to affix SMA material, such as an SMA wire122. The SMA wire122is affixed to the flat surface121by a resistance weld, similar to that illustrated inFIG.113. An adhesive123is disposed on the resistance weld. This enables a more reliable joint between the SMA wire122and the fixed end120. The adhesive123includes, but is not limited to, conductive adhesive, non-conductive adhesive, and other adhesives known in the art. FIG.115illustrates a fixed end of a bimorph arm according to an embodiment. The fixed end126of a bimorph arm includes a flat surface127to affix SMA material, such as an SMA wire128. A metallic interlayer130is disposed on the flat surface127. The metallic interlayer130includes, but is not limited to, a gold layer, a nickel layer, or alloy layer. The SMA wire128is affixed to the metallic interlayer130disposed on the flat surface127by a resistance weld129. The resistance weld129is formed using techniques including those known in the art. The metallic interlayer130enables better adhesion with the fixed end126. FIG.116illustrates a fixed end of a bimorph arm according to an embodiment. The fixed end135of a bimorph arm includes a flat surface136to affix SMA material, such as an SMA wire137. A metallic interlayer138is disposed on the flat surface136. The metallic interlayer136includes, but is not limited to, a gold layer, a nickel layer, or alloy layer. The SMA wire137is affixed to the flat surface136by a resistance weld, similar to that illustrated inFIG.115. An adhesive139is disposed on the resistance weld. This enables a more reliable joint between the SMA wire137and the fixed end135. The adhesive139includes, but is not limited to, conductive adhesive, non-conductive adhesive, and other adhesives known in the art. FIG.117illustrates a backside view of a fixed end of a bimorph arm according to an embodiment. The bimorph arm143is configured according to embodiments described herein. The fixed end143of a bimorph arm includes an island144isolated from the outer portion145of the fixed end143. This enabled the island144to be electrically and/or thermally isolated from the outer portion145. For some embodiments, SMA material affixed to the opposite side of the fixed end143of the bimorph arm is electrically coupled with the SMA material, such as an SMA wire, through a via. The island144is disposed on an insulator146, such as those described herein. The island144can be formed using etching techniques including those known in the art. FIG.118illustrates an unfixed, load point end70of a bimorph arm according to an embodiment. The unfixed, load point end70of a bimorph arm includes a flat surface71configured to include radiant surface areas74extending out from the resistance weld region73. The radiant surface areas74include a distal portion76and a proximal portion75. The flat surface71is configured to have SMA material, such as an SMA wire72, material affixed to the flat surface71. According to some embodiments, the SMA wire72is affixed to the flat surface71at a resistance weld region73by a resistance weld. The resistance weld is formed using techniques including those known in the art. For other embodiments, the SMA wire72is affixed to the flat surface71using other attachment techniques including those described herein. A temperature reduction of the unfixed, load point end70is relative to the phase transition temperature of the SMA wire72. The radiant surface area74increases the surface area of the unfixed load point end70significantly. The increased surface area improves the temperature reduction of the unfixed, load point end70. The increased surface area enables cooling to prevent shape memory alloy phase transition during actuation. FIG.119illustrates an unfixed, load point end170of a bimorph arm according to an embodiment. The unfixed, load point end170of a bimorph arm includes a flat surface171configured to include radiant surface areas174extending out from the resistance weld region173. The radiant surface areas174include a distal portion176and a proximal portion175. The flat surface171is configured to have SMA material, such as an SMA wire172, affixed to the flat surface171. According to some embodiments, the SMA wire172is affixed to the flat surface171by a resistance weld to a resistance weld region173. For other embodiments, the SMA wire172is affixed to the flat surface171using other attachment techniques including those described herein. The unfixed, load point end170also includes a proximal aperture178and a distal aperture179separated by the resistance weld region173. The proximal aperture178and distal aperture179is formed using techniques including those known in the art. While the apertures178and179are illustrated as full through features, the apertures178and179may be partially etched in some examples. The proximal aperture178and a distal aperture179physically break the flat surface171and define the position of the resistance weld region173. The apertures178and179, according to some embodiments, are configured to relieve interference between the wire172and flat surface171near the resistance weld region173. FIG.120illustrates an unfixed, load point end270of a bimorph arm according to an embodiment. The unfixed, load point end270of a bimorph arm includes a flat surface271configured to include radiant surface areas274extending out from the resistance weld region273. The flat surface271is configured to have SMA material, such as an SMA wire272, affixed to the flat surface271. According to some embodiments, the SMA wire272is affixed to the flat surface271by a resistance weld to a resistance weld region273. For other embodiments, the SMA wire272is affixed to the flat surface271using other attachment techniques including those described herein. The unfixed, load point end270also includes a proximal aperture278and a distal aperture279separated by the resistance weld region273. The unfixed, load point end270also includes an elongated aperture280corresponding to a section of the SMA wire272. The elongated aperture280can be removed to create a wire clearance for the SMA wire272. In some embodiments, the elongated aperture280extends from the proximal aperture278. While the apertures278,279, and280are illustrated as full through features, the apertures278,279, and280may be partially etched in some examples. The proximal aperture278and a distal aperture279physically break the flat surface271and define the position of the resistance weld region273. Similarly, the elongated aperture280physically break the flat surface271and define the position of the SMA wire272. The apertures278,279, and280, according to some embodiments, are configured to relieve interference between the wire272and the flat surface271near the resistance weld region273. FIG.121illustrates an unfixed, load point end370of a bimorph arm according to an embodiment. The flat surface371is configured to have SMA material, such as an SMA wire372, affixed to the flat surface371. According to some embodiments, the SMA wire372is affixed to the flat surface371by a resistance weld to a resistance weld region373, which is isolated, at least in part, by a non-linear aperture378. In some configurations, the non-linear aperture378is u-shaped, to physically isolate up to 90% of the resistance weld region373. The resistance weld region373could be mounted on a weld tongue defined by the non-linear aperture378. For other embodiments, the SMA wire372is affixed to the flat surface371using other attachment techniques including those described herein. While the non-linear aperture378is illustrated as a full through feature, the non-linear aperture378may be partially etched in some examples. The increased surface area from the radiant surface areas374enables cooling to prevent shape memory alloy phase transition during actuation. In some alternative embodiments, the resistance weld region373may be fully etched from the unfixed, load point end370. Alternatively, the resistance weld region373could also contain a partial etch slot to increase the compliance of the tongue. FIG.122illustrates an unfixed, load point end470of a bimorph arm according to an embodiment. The adjacent flat surfaces471are provided to affix SMA material, such as an SMA wire472. The SMA wire472is affixed to the flat surface471by a resistance weld region473, which is isolated, at least in part, by a non-linear aperture478. The resistance weld region473could be mounted using a partial etch slot479in the non-linear aperture478. In some configurations, the non-linear aperture478physically breaks the flat surface471and define the position of the resistance weld region473. The apertures178and179, according to some embodiments, are configured to relieve interference between the wire172and flat surface171near the resistance weld region173. While the apertures178and179are illustrated as full through features, the apertures178and179may be partially etched in some examples. The increased surface area from the radiant surface areas474enable cooling to prevent shape memory alloy phase transition during actuation. The disclosed embodiments can be applied to fixed ends of the bimorph arm.FIGS.123-125are provided herein as example embodiments of fixed ends incorporating the disclosed embodiments. FIG.123illustrates a fixed end of a bimorph arm according to an embodiment. The fixed end95of a bimorph arm includes a flat surface96to affix SMA material, such as an SMA wire97. The SMA wire97is affixed to the flat surface96by a resistance weld region98. The resistance weld region98is formed using techniques including those known in the art. The fixed end95includes a proximal aperture93and a distal aperture94separated by the resistance weld region98. The proximal aperture93and distal aperture94are formed using techniques including those known in the art. The proximal aperture93and a distal aperture94physically breaks the flat surface96and define the position of the resistance weld98. The apertures93and94, according to some embodiments, are configured to relieve interference between the SMA wire97and the flat surface96near the resistance weld region98. While the apertures93and94are illustrated as full through features, the apertures93and94may be partially etched in some examples. FIG.124illustrates a fixed end of a bimorph arm according to an embodiment. The fixed end195of a bimorph arm includes a flat surface196to affix SMA material, such as an SMA wire197. The SMA wire197is affixed to the flat surface196by a resistance weld at a resistance weld region198. The resistance weld region198is formed using techniques including those known in the art. The fixed end195includes a proximal aperture193and a distal aperture194separated by the resistance weld region198. The proximal aperture193and distal aperture194are formed using techniques including those known in the art. The fixed end195also includes an elongated aperture160corresponding to a section of the SMA wire197. The elongated aperture160can be removed to provide a wire clearance for the SMA wire197. In some embodiments, the elongated aperture160extends from the distal aperture194. The proximal aperture193and a distal aperture194physically isolate, at least in part, the resistance weld region198. The elongated aperture160physically break the flat surface196and define the position of the SMA wire197. The apertures194and196, according to some embodiments, are configured to relieve interference between the SMA wire197and the flat surface196near the resistance weld region198. While the apertures194and196are illustrated as full through features, the apertures194and196may be partially etched in some examples. FIG.125illustrates a fixed end295of a bimorph arm according to an embodiment. The fixed end295of a bimorph arm includes a flat surface296to affix SMA material, such as an SMA wire297. The SMA wire297is affixed to the flat surface296by a resistance weld at a resistance weld region298. The resistance weld region298is isolated, at least in part, by a non-linear aperture294. In some configurations, the non-linear aperture294is u-shaped, to physically isolate up to 90% of the resistance weld region298. The resistance weld298could be mounted on a weld tongue defined by the non-linear aperture294. The non-linear aperture294physically break the flat surface296and define the position of the resistance weld region298. The linear aperture294, according to some embodiments, is configured to relieve interference between the SMA wire297and the flat surface296near the resistance weld region298. In some alternative embodiments, the resistance weld region298may be fully etched from the fixed end295. Alternatively, the resistance weld region298could also contain a partial etch slot to reduce a contact area. FIG.126illustrates a balanced bimorph actuator according to an embodiment. The balanced bimorph actuator included two bimorph arms formed and configured using techniques including those described herein. The balanced bimorph actuator is configured to cancel out their own friction components since it include two bimorph arms that are arranged in opposite directions. The friction force component of each bimorph arm acts in a direction different from the wanted force stroke of each bimorph arm. According to some embodiments, a balanced bimorph actuator includes at least a first bimorph arm and at least another bimorph arm configured to have a friction force component that acts in an opposite direction of the first bimorph arm. Thus, the balanced bimorph actuator is configured to balance the sliding friction caused by one or more bimorph arms. This enables more accurate control with less or no need to actively counteract unwanted friction forces. The balanced bimorph actuator including those described herein overcome problems of other bimorph actuators that create frictional force component at the tip. These other bimorph actuators create a push in the a Y direction and also create an unwanted force in the X direction due to sliding along the surface of the pushed member of the actuator in the X direction. This will create a small amount of unwanted motion in the X direction that the control system will have to compensate for. However, these compensating Bimorph actuators will also induce their own unwanted frictional forces. This requires complex control algorithms to achieve good motion performance, for example as used in an optical image stabilization system. FIG.127illustrates an optical image stabilization including balanced bimorph actuators according to an embodiment. The balanced bimorph actuators on all sides act to cancel out their own friction components since they are arranged in opposite directions. With approximately net zero friction there is minimal open loop position error. Small errors will be, in some examples, due to typical assembly and component size tolerances and can be easily corrected by using a closed loop control system. FIG.128illustrates a balanced bimorph actuator according to an embodiment. The balanced bimorph actuator includes two bimorph arms, such as those described herein, arranged in an inline, mirrored orientation. According to some embodiments, a first bimorph arm is configured to have a friction force component in primarily in the direction of the fixed end of the first bimorph arm parallel to a longitudinal axis of the balanced bimorph actuator. The second bimorph arm is configured inline with the first bimorph arm such that the fixed end of the second bimorph arm is adjacent to the fixed end of the first bimorph arm. The second bimorph arm is configured to have a friction force component in a direction opposite to the first bimorph arm. This results in approximately a net total friction of zero for the balanced bimorph actuator. For some embodiments, each bimorph arm of the balanced bimorph actuator includes an SMA wire. In some examples, the SMA wires are connected in series and configured receive equal current to both wires, for example through a 1-channel input to control actuation of the actuator. In other examples, the SMA wires are connected in parallel and configured to receive current equal to the current of the respective sources. FIG.129illustrates a balanced bimorph actuator according to an embodiment including a polyimide layer configured to hold and isolates metal components.FIG.130illustrates a balanced bimorph actuator according to an embodiment including a common base island. The common base island is the fixed end for a first bimorph arm and a second bimorph arm. FIG.131illustrates a balanced bimorph actuator according to an embodiment. The balanced bimorph actuator includes two bimorph arms, such as those described herein, arranged in a reversed inline orientation. According to some embodiments, a first bimorph arm is configured to have a friction force component in primarily in the direction of the fixed end of the first bimorph arm parallel to a longitudinal axis of the balanced bimorph actuator. The second bimorph arm is configured inline with the first bimorph arm such that the fixed ends of the bimorph arms are at opposing ends of the bimorph actuator. Thus, the unfixed end of the first bimorph arm and the second bimorph are arranged near each other. The second bimorph arm is configured to have a friction force component in a direction opposite to the first bimorph arm. This results in approximately a net total friction of zero for the balanced bimorph actuator. For some embodiments, each bimorph arm of the balanced bimorph actuator includes an SMA wire. In some examples, the SMA wires are connected in series and configured receive equal current to both wires, for example through a 1-channel input to control actuation of the actuator. In other examples, the SMA wires are connected in parallel and configured to receive current equal to the current of the respective sources. FIG.132illustrates a balanced bimorph actuator according to an embodiment including a polyimide layer configured to hold and isolate metal components.FIG.133illustrates a balanced bimorph actuator according to an embodiment including a control input pad and a ground pad. FIG.134illustrates a balanced bimorph actuator according to an embodiment. The balanced bimorph actuator includes two bimorph arms, such as those described herein, arranged in an inline, mirrored orientation. According to some embodiments, a first bimorph arm is configured to have a friction force component in primarily in the direction of the fixed end of the first bimorph arm parallel to a longitudinal axis of the balanced bimorph actuator. The second bimorph arm is configured inline with the first bimorph arm such that the fixed end of the second bimorph arm is adjacent to the fixed end of the first bimorph arm. The second bimorph arm is configured to have a friction force component in a direction opposite to the first bimorph arm. This results in approximately a net total friction of zero for the balanced bimorph actuator. For some embodiments, a single SMA wire is used and each end of the SMA wire is coupled to a respective unfixed end of each bimorph arm. The single SMA wire enables more stroke for the balanced bimorph actuator. FIG.135illustrates a balanced bimorph actuator according to an embodiment including a single SMA wire.FIG.136illustrates a balanced bimorph actuator according to an embodiment including configured with for a single SMA wire, a control input pad, and a ground pad. FIG.137illustrates a balanced bimorph actuator according to an embodiment. The balanced bimorph actuator includes two bimorph arms, such as those described herein, arranged in a staggered orientation. According to some embodiments, a first bimorph arm is configured to have a friction force component in primarily in the direction of the fixed end of the first bimorph arm parallel to a longitudinal axis of the first bimorph arm. The second bimorph arm is configured to be staggered with the first bimorph arm such longitudinal axis of the second bimorph arm is approximately parallel to the longitudinal axis of the first bimorph arm. Further, the fixed ends of the bimorph arms are at opposing ends of the bimorph actuator. Thus, the unfixed end of the first bimorph arm and the second bimorph are staggered with respect to each other. The second bimorph arm is configured to have a friction force component in a direction opposite to the first bimorph arm. This results in approximately a net total friction of zero for the balanced bimorph actuator. For some embodiments, each bimorph arm of the balanced bimorph actuator includes an SMA wire. In some examples, the SMA wires are connected in series and configured receive equal current to both wires, for example through a 1-channel input to control actuation of the actuator. In other examples, the SMA wires are connected in parallel and configured to receive current equal to the current of the respective sources. FIG.138illustrates a balanced bimorph actuator with a staggered orientation according to an embodiment including a polyimide layer configured to hold and isolate metal components.FIG.139illustrates a balanced bimorph actuator according to an embodiment including a control input pad and a ground pad. FIG.140illustrates an optical image stabilization including balanced bimorph actuators according to an embodiment. The balanced bimorph actuators on all sides act to cancel out their own friction components since they are arranged in opposite directions. With approximately net zero friction there is minimal open loop position error. Small errors will be, in some examples, due to typical assembly and component size tolerances and can be easily corrected by using a closed loop control system. FIG.141illustrates an exploded view of an optical image stabilization including balanced bimorph actuators according to an embodiment. The optical image stabilization is configured to receive bimorph actuators, such as those described herein, that self-locates flush into a pocket on the outer housing. This arrangement enables a smaller X/Y footprint of the bimorph module by having bimorph actuators, such as the balanced bimorph actuators described herein, share the same X/Y space as the outer housing. This also simplifies assembly of the bimorph module by enabling bimorph actuators to be inserted at the final step from the outside. The outer housing can be made from molded plastic, metal or other materials. FIG.142illustrates an optical image stabilization including balanced bimorph actuators according to an embodiment. The optical image stabilization is configured to receive bimorph actuators, such as those described herein, that self-locates flush into a pocket on the outer housing. This arrangement enables a smaller X/Y footprint of the bimorph module by having bimorph actuators, such as the balanced bimorph actuators described herein, share the same X/Y space as the outer housing. This also simplifies assembly of the bimorph module by enabling bimorph actuators to be inserted at the final step from the outside. The outer housing can be made from molded plastic, metal or other materials. FIG.143illustrates a sensor shift optical image stabilization including bimorph actuators according to an embodiment. The optical image stabilization is configured to receive balanced bimorph actuators, such as those described herein, configured as a balanced carriage. The bimorph carriage configured to insert from the outside of the sensor shift OIS module. For some embodiments, the sensor shift OIS uses the design of the bimorph actuators off center to also induce rotation of the image sensor which can be controlled for suppressing roll excitation as well as X/Y excitation. This arrangement enables a smaller X/Y footprint of the bimorph module by having bimorph actuators, such as the balanced bimorph actuators described herein, share the same X/Y space as the outer housing. This also simplifies assembly of the bimorph module by enabling bimorph actuators to be inserted at the final step from the outside. The outer housing can be made from molded plastic, metal or other materials. FIG.144illustrates an optical image stabilization including balanced bimorph actuators according to an embodiment. The optical image stabilization is configured to receive bimorph actuators, such as those described herein, that self-locates flush into a pocket on the outer housing. This arrangement enables a smaller X/Y footprint of the bimorph module by having bimorph actuators, such as the balanced bimorph actuators described herein, share the same X/Y space as the outer housing. This also simplifies assembly of the bimorph module by enabling bimorph actuators to be inserted at the final step from the outside. The outer housing can be made from molded plastic, metal or other materials. FIG.145illustrates a metal outer housing manufactured as formed metal that is attached with molded plastic in an insert molding process.FIG.146illustrates a metal outer can embodiment including formed pockets into the 4 sides of the outer can configured to allow for the flush mounting of bimorph actuators, such as those described herein. FIG.147illustrates an optical image stabilization147including bimorph actuators according to an embodiment. The optical image stabilization147includes an actuator1470showing side view of bimorphs1471positioned about the actuator1470. Each bimorph1471may be configured with a bearing element1472positioned between the bimorph1471and an outer contact surface1473of the actuator1470according to an embodiment. The four bimorphs1471may be formed and configured using techniques including those described herein. It is understood that the optical image stabilization147may include more or less bimorphs than the four illustrated herein. The actuator1471includes a bearing element1472configured to minimize or reduce friction between the bimorph1471and an outer contact surface1473of the actuator1470. In some examples, a lubrication material may be used to further decrease the friction of the bearing element1472. For example a suitable lubricant, such as but not limited to clean room grease, may be employed as a means to provide lubrication for the bearing element1472. Additionally, a suitable lubricant may be use as a means to assist in keeping the bearing elements in place. The bimorph actuators on all sides act to minimize their own friction components by incorporating bearing elements. With approximately net zero friction there is minimal open loop position error. Small errors will be, in some examples, due to typical assembly and component size tolerances and can be easily corrected by using a closed loop control system. The incorporation of bearing elements1472enables more accurate control with less or no need to actively counteract unwanted friction forces. The actuator1470including those bimorphs1471described herein overcome problems of other bimorph actuators that create frictional force component at the tip. These other bimorph actuators create a push in the Y direction and also create an unwanted force in the X direction due to sliding along the surface of the pushed member of the actuator in the X direction. This will create a small amount of unwanted motion in the X direction that the control system will have to compensate for. However, these compensating Bimorph actuators will also induce their own unwanted frictional forces. This requires complex control algorithms to achieve good motion performance, for example as used in an optical image stabilization system147. FIG.148Ais an isometric view of a bimorph actuator1480with a formed sphere1486. The sphere1486is configured to reduce or minimize friction, and may sometimes be referred to herein as a friction-reducing sphere or bearing. The bimorph actuator1480may include a base island1485, an unfixed, load point end1487, and metal beams1481connecting the unfixed, load point end1487to the base island1485. The sphere1486may be formed on the unfixed, load point end1487.FIG.148Bis a detailed view of the unfixed, load point end1487and the sphere1486formed thereon.FIG.149is a top and side view of the bimorph actuator1480ofFIG.148Aaccording to an embodiment. The bimorph actuator1480includes a control input pad1483and a ground pad1484. The design of the friction-reducing sphere1486may, for example, control the vectors of normal forces that bear on the moving parts while minimizing the surface contact area between the moving parts. The sphere1486is configured to reduce friction and may facilitate the desired motion by minimizing friction between the bimorph actuator1480and the outer contact surface of the actuator (ofFIG.147). This results in approximately a minimized friction for the bimorph actuator. For some embodiments, each metal beam1481of the bimorph actuator1480includes an SMA wire1482. In some examples, the SMA wires1482are connected in series and configured to receive equal current to both wires, for example through a 1-channel input to control actuation of the bimorph actuator1480. In other examples, the SMA wires1482are connected in parallel and configured to receive current equal to the current of the respective sources. FIG.150is a top and side view of a bimorph actuator1500with a ball bearing1501housed in an unfixed, load point end1587, according to an embodiment. The unfixed, load point end1587includes a bearing configured to reduce or minimize friction, which may be configured as a cantilevered element1502of the unfixed, load point end1587. The cantilevered element1502may include a semi-circle receiving space containing at least one freely revolving metal ball (ball bearing1501). The ball bearing1501includes at least one rolling element such as balls with a circular cross-section. The balls may be secured within the unfixed, load point end1587of the bimorph actuator1500by the cantilevered element1502. The design of the ball bearing1501may, for example, control the vectors of normal forces that bear on the moving parts while minimizing the surface contact area between the moving parts. The ball bearing1501may facilitate the desired motion by minimizing friction between the bimorph actuator1500and the outer contact surface of the actuator (ofFIG.147). In some examples, a lubrication material may be implemented to further decrease the friction of the ball bearing1501. For example, a clean room grease may be implemented as a means of lubrication for the ball bearing1501. Additionally, a suitable lubricant may be used to assist in keeping the ball bearing in place. For some embodiments, each metal beam1581of the bimorph actuator1500includes an SMA wire1582. In some examples, the SMA wires1582are connected in series and configured to receive equal current to both wires, for example through a 1-channel input to control actuation of the bimorph actuator1500. In other examples, the SMA wires1582are connected in parallel and configured to receive current equal to the current of the respective sources. FIG.151is a top and side view of a bimorph actuator1510with a ball bearing1511housed in an unfixed, load point end1587, according to an embodiment. The unfixed, load point end1587includes a bearing1512configured to reduce friction, which may be mounted to the unfixed, load point end1587. The friction-reducing bearing1512may secured to the unfixed, load point end1587at weld points1512A and1512B. In other examples, the friction-reducing bearing1512may be secured to the unfixed, load point end1587using other disclosed techniques. The friction-reducing bearing1512include a semi-circle receiving space containing at least one freely revolving metal ball (ball bearing1511). The ball bearing1511includes at least one rolling element such as balls with a circular cross-section. The balls may be secured within the unfixed, load point end1587of the bimorph actuator1510by the friction-reducing bearing1512. The design of the ball bearing1511may, for example, control the vectors of normal forces that bear on the moving parts while minimizing the surface contact area between the moving parts. The ball bearing1511may facilitate the desired motion by minimizing friction between the bimorph actuator1510and the outer contact surface of the actuator (ofFIG.147). In some examples, a lubrication material may be implemented to further decrease the friction of the ball bearing1511. For example, a clean room grease may be implemented as a means of lubrication for the ball bearing1511. Additionally, a suitable lubricant may be used to assist in keeping the ball bearing in place. FIG.152is a top and side view of a bimorph actuator1520with a spherical bearing1521housed in an unfixed, load point end1587, according to an embodiment. The spherical bearing1521includes a shaft1521B rotating between apertures formed from the unfixed, load point end1587. The apertures of the unfixed, load point end1587are formed between the unfixed, load point end1587and bearings1522configured to reduce friction, which may be mounted to the unfixed, load point end1587. The friction-reducing bearings1522may secured to the unfixed, load point end1587at weld points1522A and1522B. In other examples, the friction-reducing bearing1522may be secured to the unfixed, load point end1587using other disclosed techniques. The bearing1522include a semi-circle receiving space containing at least a portion of the shaft1521B rotating of the spherical bearing1521. The spherical bearing1521includes at least one rolling element such as a roller1521A with a circular cross-section. The shaft1521B may be configured to rotate while being secured to the unfixed, load point end1587of the bimorph actuator1520by the friction-reducing bearing1522. The design of the spherical bearing1521may, for example, control the vectors of normal forces that bear on the moving parts while minimizing the surface contact area between the moving parts. The spherical bearing1521may facilitate the desired motion by minimizing friction between the bimorph actuator1510and the outer contact surface of the actuator (ofFIG.147). In some examples, a lubrication material may be implemented to further decrease the friction of the spherical bearing1521. For example, a clean room grease may be implemented as a means of lubrication for the spherical bearing1521. Additionally, a suitable lubricant may be used to assist in keeping the spherical bearing in place. FIG.153is a top and side view of a bimorph actuator1530with a spherical bearing1531housed in an unfixed, load point end1587, according to an embodiment. The spherical bearing1531includes at least one rolling element such as a roller1531A with a circular cross-section. The spherical bearing1531also includes a shaft1531B rotating between apertures of the unfixed, load point end1587. The apertures of the unfixed, load point end1587are formed between the alignment of a first cantilevered element1532A and a second cantilevered element1532B of the unfixed, load point end1587. It is understood that multiple cantilevered elements may be implemented herein. The first cantilevered element1532A may include semi-circle element that is positioned in a first direction. Whereas, the second cantilevered element1532B may include semi-circle element that is positioned in a second direction, opposite the first direction. In this way, the alignment of the first cantilevered element1532A and the second cantilevered element1532B may create a therethrough configured to receive a portion of the shaft1531B of the spherical bearing1531. The design of the spherical bearing1531may, for example, control the vectors of normal forces that bear on the moving parts while minimizing the surface contact area between the moving parts. The spherical bearing1531may facilitate the desired motion by minimizing friction between the bimorph actuator1530and the outer contact surface of the actuator (ofFIG.147). FIG.154Ais a top and side view of a spherical bearing1541in the unfixed, load point end1587in an open state, according to an embodiment.FIG.154Bis a top and side view of a spherical bearing in the unfixed, load point end1587in a closed state, according to an embodiment. The unfixed, load point end1587includes a first configurable cantilevered element1542A and a second configurable cantilevered element1542B extending from the unfixed, load point end1587. This is referred as the open state, and is illustrated inFIG.154A. The distal ends of both the first configurable cantilevered element1542A and the second configurable cantilevered element1542B may be configured to be folded over a portion of the length of each respective cantilevered element creating apertures of the unfixed, load point end1587. This is referred as the closed state, and is illustrated inFIG.154B. The spherical bearing1541also includes a shaft1541B rotating between apertures of the unfixed, load point end1587in the closed state. The apertures of the unfixed, load point end1587are formed between the alignment of the first configurable cantilevered element1542A and the second configurable cantilevered element1542B of the unfixed, load point end1587. In this way, the alignment of the first configurable cantilevered element1542A and the second configurable cantilevered element1542B may create a therethrough configured to receive a portion of the shaft1541B of the spherical bearing1541. It will be understood that terms such as “top,” “bottom,” “above,” “below,” and x-direction, y-direction, and z-direction as used herein as terms of convenience that denote the spatial relationships of parts relative to each other rather than to any specific spatial or gravitational orientation. Thus, the terms are intended to encompass an assembly of component parts regardless of whether the assembly is oriented in the particular orientation shown in the drawings and described in the specification, upside down from that orientation, or any other rotational variation. It will be appreciated that the term “present invention” as used herein should not be construed to mean that only a single invention having a single essential element or group of elements is presented. Similarly, it will also be appreciated that the term “present invention” encompasses a number of separate innovations, which can each be considered separate inventions. Although the present invention has been described in detail with regards to the preferred embodiments and drawings thereof, it should be apparent to those skilled in the art that various adaptations and modifications of embodiments of the present invention may be accomplished without departing from the spirit and the scope of the invention. Additionally, the techniques described herein could be used to make a device having two, three, four, five, six, or more generally n number of bimorph actuators and buckle actuators. Accordingly, it is to be understood that the detailed description and the accompanying drawings as set forth hereinabove are not intended to limit the breadth of the present invention, which should be inferred only from the following claims and their appropriately construed legal equivalents. | 116,427 |
11859599 | DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring toFIG.2, a first preferred embodiment of a vacuum arc thruster with multi-layer insulation is shown. The vacuum arc thruster3is adapted to be operated in a vacuum environment. The vacuum arc thruster3includes a housing31, an anode unit32, a cathode unit33, and an insulator34. A central axis R is defined by the housing31. The housing31includes an inner peripheral wall311and an electric discharging room312enclosed by the inner peripheral wall311. The anode unit32, the cathode unit33, and the insulator34are disposed in the electric discharging room312. The insulator34is located between the anode unit32and the cathode unit33so that the cathode unit33is spaced apart from the anode unit32. In an example as shown in the preferred embodiments of this invention, the anode unit32can be located in a center of the housing31along the central axis R, and the cathode unit33can touch the inner peripheral wall311so that the cathode unit33is in close contact with the housing31. Therefore, it is shown in the figure that the cathode unit33, the insulator34, and the anode unit32are sequentially arranged from the inner peripheral wall311to the central axis R. Specifically, in the electric discharging room312, the inner peripheral wall311surrounds the cathode unit33, the cathode unit33surrounds the insulator34, and the insulator34surrounds the anode unit32. In the example as shown in the preferred embodiments of this invention, the cathode unit33, the insulator34(including fuel layers341and insulating layers342which are hereinafter described), and the anode unit32can be in concentric relationship with one another around the central axis R. The insulator34, as shown inFIG.2A, includes a plurality of fuel layers341and a plurality of insulating layer342, and herein the term “a plurality of” denotes two or more than two. Each insulating layer342is disposed between every two adjacent fuel layers341so that the fuel layers341and the insulating layers342are arranged in an alternating manner to form a multiple-layer (multi-layer) design. The number of fuel layers341and the number of insulating layers342can be adjusted according to demand. As shown inFIG.2, when the insulator34is encircled by the cathode unit33, and the anode unit32is encircled by the insulator34, it is noted that the cathode unit33can surround the outermost fuel layer341furthest from the central axis R, and the innermost fuel layer341closest to the central axis R can surround the anode unit32. In addition, the material of the fuel layer341is different from the material of the insulating layer342. For instance, the fuel layer341can be made of graphite or other suitable materials. The insulating layer342can be made of TEFLON or other suitable materials. The term “TEFLON” is a registered trademark used for Polytetrafluoroethylene (PTFE), sold under the trademark TEFLON™. In this preferred embodiment, the graphite and TEFLON are adopted as an example. It is also noted that an end of the insulator34can be perpendicular to the central axis R. Specifically, one end of each fuel layer341forms a first surface3411, and one end of each insulating layer342forms a second surface3421. The first surface3411and the second surface3421are perpendicular to the central axis R. Therefore, the first surface3411and the second surface3421can be plane. The thruster can also include a control device35. The control device35is connected to the anode unit32and the cathode unit33respectively and adapted to control an electric discharging operation of the anode unit32and the cathode unit33, thereby generating electric arcs by which plasma is generated to facilitate the generation of thrust. The control device35is included in the preferred embodiments of this invention. The operation of this invention is described with the aid ofFIG.2. The anode unit32and the cathode unit33are activated under the control of the control device35to induce an electric discharge reaction. Because the electrodes, namely the anode unit32and the cathode unit33, the fuel layers341, and the insulating layers342can be made of different materials, a distortion of an electric field takes place at junctions between these different materials in a vacuum environment, and the distorted electric field implies an easy generation of electric arcs to achieve a more significant field emission effect. In the example as shown in FIG.3, the electric arc generated at one electrode, such as the cathode unit33which can be made of metal, passes a strong electric field gradient area providing multi-interfaces between the fuel layers341and the insulating layers342and then moves to the other electrode, such as the anode unit32which can be made of metal. At this moment, the electric arc, as shown inFIG.4, bombards the surface of the metal electrode to generate plasma and ablates the metal fuel, thereby generating thrust by which the vacuum arc thruster3is actuated and operated in the vacuum environment. Accordingly, the insulator4is formed into a multi-layer structure because of the insulating layers342and the fuel layers341made of different materials and arranged in an alternating manner. The insulator4and the two electrodes, namely the cathode unit33and the anode unit32, also differ in material. In this regards, the distortion of the electric field occurs at the interfaces, i.e. junctions, between different materials while exerting high voltage on the insulator34, which allows the electric arc to punch through easily and ablate the conductive substance generated on the surface of the fuel layers341, thereby changing the dielectric constant within the electric discharging room312. This phenomenon allows the plasma to be easily generated within the electric discharging room312for further generation of the thrust, which can increase the stability of the initial operation of the thruster3. Unlike the conventional structure shown inFIG.1, the multi-layer structure of the insulator34neither puts the graphite membrane15on the surface of the insulator14for discharging nor causes the thin graphite membrane15to be easily run out because of an increase in the number of discharges. Therefore, the electric field between the anode unit32and the cathode unit33is fully triggered to fulfill the maximum efficacy with the aid of the fuel layers341and the insulating layers342, which allows the electric discharging operation to be more stable, attains a longer discharging life, and prolongs the service life of the vacuum arc thruster3in an efficient manner. Referring toFIG.5andFIG.5A, a second preferred embodiment of a vacuum arc thruster with multi-layer insulation is shown. The vacuum arc thruster3still includes the housing31, the anode unit32, the cathode unit33, the insulator34, and the control device35. The concatenation of correlated elements, operations, and effects of the second preferred embodiment are the same as those of the first preferred embodiment and herein are omitted. In particular, the second preferred embodiment differs from the first preferred embodiment in having the end of the insulator34which is inclined to the central axis R. Specifically, each first surface3411of each fuel layer341and each second surface3421of each insulating layer342can be inclined to the central axis R, so the first surface3411and the second surface3421are formed into a slanted surface. Accordingly, when the anode unit32and the cathode unit33are activated under the control of the control device35to induce an electric discharge reaction, the slope of the slanted surface helps strengthen the field emission effect with generation of electrons for achieving an efficient utilization of the electrons, increases the operating stability and efficacy of the vacuum arc thruster1, and extends the duration thereof, i.e. prolongs the service life. To sum up, this invention takes advantage of the insulator formed into a multi-layer structure, i.e. a structure with multiple layers, by alternating fuel layers with insulating layers. This allows the physical phenomenon of “triple junction” to take place at the interfaces between the fuel layers, the insulating layers, and a vacuum environment. Accordingly, the maximum efficacy can be fulfilled within the electric field between the anode unit and the cathode unit by means of the insulator, the stability and efficacy of the operation of the thruster can be efficiently enhanced, and the service life of the thruster can be prolonged. While the embodiments are shown and described above, it is understood that further variations and modifications may be made without departing from the scope of this invention. | 8,700 |
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