阅读说明：本技术 具有喷射泵的共轨燃料系统以及其使用方法 (Common rail fuel system with injection pump and method of use thereof ) 是由 S·贝格龙 E·普拉蒙登 J·G·戈夫罗 B·雷诺 于 2020-09-03 设计创作，主要内容包括：本发明涉及具有喷射泵的共轨燃料系统以及其使用方法。一种操作飞行器的飞行器发动机的方法,所述飞行器发动机具有用于将燃料喷射到所述飞行器发动机的燃烧室中的共轨燃料喷射系统,所述方法包括：通过所述共轨喷射系统对燃料进行加压以进行循环；通过喷射泵的动力流入口使所述加压燃料的一部分循环；以及利用通过所述动力流入口循环的所述加压燃料的所述一部分通过所述喷射泵夹带流。(The invention relates to a common rail fuel system with an injection pump and a method of using the same. A method of operating an aircraft engine of an aircraft having a common rail fuel injection system for injecting fuel into a combustion chamber of the aircraft engine, the method comprising: pressurizing fuel for circulation by the common rail injection system; circulating a portion of the pressurized fuel through a motive flow inlet of a jet pump; and entraining a flow with the jet pump with the portion of the pressurized fuel circulated through the motive flow inlet.)

1. A method of operating an aircraft engine of an aircraft having a common rail fuel injection system for injecting fuel into a combustion chamber of the aircraft engine, the method comprising:

pressurizing fuel for circulation by the common rail injection system;

circulating a portion of the pressurized fuel through a motive flow inlet of the jet pump; and

entraining a flow through the jet pump with the portion of the pressurized fuel circulated through the motive flow inlet.

2. The method of claim 1, wherein the portion of the pressurized fuel is a return flow of fuel from at least one common rail injector of the common rail fuel injection system, the method comprising circulating the return flow of fuel through the motive flow inlet of the injection pump.

3. The method of claim 1 or 2, further comprising diverting the portion of the pressurized fuel from at least one fuel conduit to the injection pump, at least a fuel conduit connecting a high pressure pump to at least one common rail injector of the common rail injection system.

4. The method of claim 2, further comprising diverting the fuel from at least one fuel conduit connecting a high pressure pump to at least one common rail injector of the common rail fuel injection system and entraining the flow with both the return flow of the fuel and the diverted fuel.

5. A method according to any preceding claim, wherein the jet pump is fluidly connected to a fuel source, the method comprising entraining fuel from the fuel source by the jet pump using the portion of the pressurised fuel.

6. The method of claim 3, further comprising adjusting a flow rate of the diverted portion of the pressurized fuel.

7. The method of claim 6, wherein adjusting the flow rate comprises restricting flow of the diverted portion of the pressurized fuel.

8. The method of any of the preceding claims, wherein entraining the flow with the portion of the pressurized fuel by the jet pump comprises entraining fuel directly from a fuel tank.

9. The method of any of the preceding claims, wherein entraining the flow with the portion of the pressurized fuel with the jet pump includes drawing the fuel through a main fuel conduit that fluidly connects the fuel source to a high pressure pump.

10. An aircraft engine, the aircraft engine comprising: at least one combustion chamber; a fuel pump fluidly connected to a source of fuel; a common rail injector having an injector inlet fluidly connected to the fuel pump via a fuel conduit (124), a first injector outlet fluidly connected to the at least one combustion chamber, and a second injector outlet for outputting a return flow of fuel; and an ejector pump having a motive flow inlet fluidly connected to one of the second injector outlet and the fuel conduit upstream of the common rail injector and an entrainment flow inlet for receiving fuel to be drawn by the ejector pump.

11. The aircraft engine of claim 10 wherein the motive flow inlet is fluidly connected to both the second injector outlet and the fuel conduit.

12. The aircraft engine of claim 10 or 11 wherein the motive flow inlet is fluidly connected to the fuel conduit via a bypass conduit to which a flow control device is fluidly connected.

13. The aircraft engine of any one of claims 10 to 12 wherein the fuel source is a fuel tank and the jet pump is located within the fuel tank.

14. The aircraft engine according to any one of claims 10 to 13, further comprising: a main fuel conduit fluidly connecting the fuel source to the fuel pump; and a boost pump fluidly connected to the main fuel conduit, the jet pump being connected to the main fuel conduit upstream of the boost pump.

Technical Field

The present application relates generally to aircraft engines and more particularly to fuel systems for use in such aircraft engines.

Background

Aircraft engines comprise at least one combustion chamber into which fuel is typically provided by fuel injectors. Some fuel injectors, such as common rail injectors, produce a return flow of fuel. The energy of the return flow is typically wasted because the fuel return flow is typically returned directly to the fuel tank. Therefore, better and more efficient fuel management is desired in such fuel systems.

Disclosure of Invention

In one aspect, a method of operating an aircraft engine of an aircraft having a common rail fuel injection system for injecting fuel into a combustion chamber of the aircraft engine is provided, the method comprising: pressurizing fuel for circulation by a common rail injection system; circulating a portion of the pressurized fuel through a motive flow inlet of the jet pump; and entraining the flow with the jet pump with a portion of the pressurized fuel circulated through the motive flow inlet.

The method of operating an aircraft engine as defined above and herein may further include one or more of the following additional steps and/or features, in whole or in part.

A portion of the pressurized fuel is a return flow of fuel from at least one common rail injector of a common rail fuel injection system, the method including circulating the return flow of fuel through a motive flow inlet of an injection pump.

A portion of the pressurized fuel is diverted from at least one fuel conduit to an injection pump, at least the fuel conduit connecting the high pressure pump to at least one common rail injector of a common rail injection system.

The method includes diverting fuel from at least one fuel conduit connecting a high pressure pump to at least one common rail injector of a common rail fuel injection system and entraining a flow with both the return flow of fuel and the diverted fuel.

The jet pump is fluidly connected to the fuel source, and the method includes entraining fuel from the fuel source with a portion of the pressurized fuel through the jet pump.

The flow rate of the diverted portion of the pressurized fuel is adjusted.

Adjusting the flow rate includes restricting flow of the diverted portion of the pressurized fuel.

Entraining a flow through the jet pump with a portion of the pressurized fuel includes entraining fuel directly from the fuel tank.

Entraining the flow with a portion of the pressurized fuel with the jet pump includes drawing the fuel through a main fuel conduit fluidly connecting the fuel source to the high pressure pump.

In another aspect, a method of supplying fuel to an aircraft engine having a common rail fuel injection system is provided, the method comprising: pressurizing fuel for circulation by a common rail injection system; injecting a portion of the fuel in a common rail injector of the common rail injection system, thereby generating a return flow of the fuel; and entraining fuel to be pressurized from the fuel source with the jet pump using a return flow of fuel circulated through the motive flow inlet of the jet pump.

The method of supplying fuel to an aircraft engine as defined above and herein may further comprise one or more of the following additional steps and/or features, in whole or in part.

The fuel is diverted from a fuel conduit connecting the high pressure pump to a common rail injector of a common rail injection system and the fuel is entrained with both the return flow of fuel and the diverted fuel.

The flow rate of the diverted fuel is adjusted.

Adjusting the flow rate includes restricting the flow of diverted fuel.

Entraining fuel from the fuel source via the jet pump includes entraining fuel directly from the fuel tank.

Entraining fuel from a fuel source with a jet pump includes drawing fuel through a main fuel conduit fluidly connecting the fuel source to a high pressure pump.

In yet another aspect, an aircraft engine is provided, comprising: at least one combustion chamber; a fuel pump fluidly connected to a source of fuel; a common rail injector having an injector inlet fluidly connected to the fuel pump via a fuel conduit, a first injector outlet fluidly connected to the at least one combustion chamber, and a second injector outlet for outputting a return flow of fuel; and an ejector pump having a motive flow inlet fluidly connected to one of the second injector outlet and the fuel conduit upstream of the common rail injector and an entrainment flow inlet for receiving fuel to be drawn by the ejector pump.

The aircraft engine fuel system as defined above and herein may further include one or more of the following additional features, in whole or in part.

The motive flow inlet is fluidly connected to both the second injector outlet and the fuel conduit.

The motive flow inlet is fluidly connected to the fuel conduit via a bypass conduit, and the flow control device is fluidly connected to the bypass conduit.

The fuel source is a fuel tank and the injection pump is located within the fuel tank.

A main fuel conduit fluidly connects the fuel source to the fuel pump, and a booster pump fluidly connects to the main fuel conduit, the jet pump being connected to the main fuel conduit upstream of the booster pump.

Drawings

Referring now to the drawings wherein:

FIG. 1 is a block diagram of a compound engine system;

FIG. 2 is a schematic cross-sectional view of a rotary internal combustion engine according to certain embodiments;

FIG. 3 is a schematic illustration of an engine assembly according to one embodiment; and

FIG. 4 is a schematic cross-sectional view of an injection pump that may be used with the engine assembly of FIG. 3.

Detailed Description

Referring to FIG. 1, a compound engine system 8 is schematically illustrated. The system 8 includes a compressor 11 and a turbine 13 connected by a shaft 15 and acting as a turbocharger for one or more rotary engines 10. The compressor 11 may be a single or multi-stage centrifugal device and/or an axial device. The rotary engine 10 or rotary engines receive compressed air from a compressor 11. Air is optionally circulated through an intercooler between the compressor 11 and the rotary engine(s) 10.

The exhaust gases exiting from the rotary engine 10 are supplied to a compressor turbine 13 and also to a power turbine 17, the turbines 13, 17 being shown here as being arranged in series, i.e. wherein the exhaust gases first flow through one of the two turbines, which is at reduced pressure, and then through the other turbine, which is at a further reduced pressure. In an alternative embodiment (not shown) the turbines 13, 17 are arranged in parallel, i.e. wherein the exhaust gas is branched off and supplied to each turbine at the same pressure. In another alternative embodiment, only one turbine is provided.

Energy is extracted from the exhaust gas by the compressor turbine 13 to drive the compressor 11 via the connecting shaft 15, and by the power turbine 17 to drive the output shaft 19. The output shaft 19 may be connected via a gear system 21 to a shaft 22, which shaft 22 is connected to the rotary engine(s) 10. The combined output on the shafts 19, 22 may be used to provide propulsion power for vehicle applications in which the system 8 is integrated. This power may be transmitted through a gearbox (not shown) that adjusts the output speed of the shafts 19, 22 to the desired speed on the application. In an alternative embodiment, the two shafts 19, 22 may be used independently to drive separate elements, such as propellers, helicopter rotors, load compressors or generators, depending on whether the system is a turboprop, turboshaft or Auxiliary Power Unit (APU).

Although not shown, the system 8 also includes a cooling system comprising: a circulation system for coolant (e.g. water-glycol, oil, air) for cooling the outer body of the rotary engine; an oil coolant for internal mechanical parts of the rotary engine; one or more coolant heat exchangers, etc.

The compound engine system 8 may be as described in U.S. patent No. 7,753,036 issued to lentinus et al on day 7/2010 and day 13 or as described in U.S. patent No. 7,775,044 issued to Julien et al on day 8/2010 and day 17, both of which are incorporated herein by reference in their entirety.

The rotary engine 10 forms the core of the compound cycle engine system 8. Referring to fig. 2, a rotary internal combustion engine 10, referred to as a wankel engine, is schematically illustrated. The rotary internal combustion engine 10 includes an outer body 12 having axially spaced end walls 14 with a peripheral wall 18 extending therebetween to form a rotor cavity 20. The inner surface of the peripheral wall 18 of the cavity 20 has a profile defining two lobes, which is preferably an epitrochoid (epitrochochoid).

An inner body or rotor 24 is received within the cavity 20. The rotor 24 has axially spaced end faces 26 adjacent the outer body end wall 14 and a peripheral face 28 extending therebetween. The peripheral face 28 defines three circumferentially spaced apart apex portions 30 and a generally triangular profile having outwardly arcuate sides 36. The tip portion 30 sealingly engages the inner surface of the peripheral wall 18 to form three rotating combustion chambers 32 between the inner rotor 24 and the outer body 12. The geometric axis of the rotor 24 is offset from and parallel to the axis of the outer body 12.

The combustion chamber 32 is sealed. In the illustrated embodiment, each rotor tip section 30 has a tip seal 52 that extends from one end face 26 to the other and is biased radially outward against the peripheral wall 18. End seals 54 engage each end of each tip seal 52 and are biased against the respective end wall 14. Each end face 26 of the rotor 24 has at least one arcuate face seal 60 extending from each apex portion 30 to each adjacent apex portion 30, adjacent to but within the rotor periphery throughout its length, in sealing engagement with the end seals 54 adjacent each end thereof and biased into sealing engagement with the adjacent end wall 14. Alternative sealing arrangements are also possible.

Although not shown in the drawings, the rotor 24 is journalled on an eccentric portion of the shaft such that the shaft rotates the rotor 24 for orbital movement within the stator cavity 20. As the rotor 24 rotates about the stator cavity 20, the shaft rotates three times for each complete rotation of the rotor 24. An oil seal is provided around the eccentric to prevent leakage flow of its lubricating oil radially outwardly between the respective rotor end face 26 and the outer body end wall 14. During each rotation of the rotor 24, each chamber 32 is of different volume and moves around the stator cavity 20 to undergo four phases of intake, compression, expansion and exhaust, which are similar to the strokes in a reciprocating internal combustion engine having a four-stroke cycle.

The engine includes a primary inlet port 40 in communication with an air source, a discharge port 44, and an optional purge port 42 also in communication with the air source (e.g., compressor) and located between the inlet port 40 and the discharge port 44. The ports 40, 42, 44 may be defined in the end wall 14 in the peripheral wall 18. In the illustrated embodiment, an inlet port 40 and a purge port 42 are defined in the end wall 14 and communicate with the same inlet tube 34 defined as a passage in the end wall 14, and an exhaust port 44 is defined through the peripheral wall 18. Alternative configurations are possible.

In particular embodiments, a fuel such as kerosene (jet fuel) or other suitable fuel is delivered into the chamber 32 through a fuel port (not shown) such that the chamber 32 stratifies into a rich fuel-air mixture near the ignition source and a lean mixture elsewhere, and the fuel-air mixture may be ignited within the enclosure using any suitable ignition system known in the art (e.g., spark plug, glow plug). In a particular embodiment, the rotary engine 10 operates under the principles of the miller or atkinson cycle with appropriate relative positioning of the main inlet port 40 and the exhaust port 44, wherein its compression ratio is lower than its expansion ratio.

Referring to FIG. 3, an engine assembly is shown generally at 100. The engine assembly 100 may incorporate the compound cycle engine system 8 described above with reference to FIG. 1 and may include the rotary engine 10 described above with reference to FIG. 2. However, engine 10 may be any internal combustion engine, such as a gas turbine engine, a piston engine, a rotary engine. The disclosed engine assembly may also be embodied as a gas turbine engine for use as an Auxiliary Power Unit (APU) in an aircraft. Thus, an "internal combustion engine" as used herein is understood to include all these types of engines (reciprocating internal combustion engines such as piston engines, rotary internal combustion engines such as rotary or wankel engines, continuous flow engines such as gas turbine engines) and is thus defined as any engine having one or more combustion chambers and having a fuel system feeding the fuel to the combustion chamber(s). The fuel system of the present engine uses common rail injection, as will be described further below.

The engine assembly 100 includes a fuel injection system 102 for providing fuel to the internal combustion engine 10 from a fuel source S, which in the illustrated embodiment includes a fuel tank. As shown, the fuel injection system 102 includes one or more high pressure pumps 104 and common rail injectors 106. Common rail injector 106 includes a common rail 108 and individual injectors, also referred to as common rail injectors 110. The common rail 108 is in fluid communication with each of the injectors 110.

In the illustrated embodiment, the engine assembly 100 includes a controller 105, which may be a Full Authority Digital Engine Control (FADEC). The controller 105 may be operably connected to a power lever 107 that may be manually operated by a pilot of an aircraft equipped with the disclosed engine assembly 100. The controller 105 is in communication with a high pressure fuel sensor 109, and with a speed sensor 111, the high pressure fuel sensor 109 being operatively connected to the high pressure pump(s) 104 to determine fuel pressure, the speed sensor 111 being operatively connected to the engine 10 to determine the speed of the engine 10. By receiving pressure and speed data from the pressure and fuel sensors 109, 111, the controller 105 controls the amount of fuel to be injected by the injector 110 so that the engine 10 delivers the power required by the pilot via the power lever 107.

Still referring to fig. 3, each of the fuel injectors 110 includes an inlet 110a, a first outlet 110b, and a second outlet 110 c. In the illustrated embodiment, inlet 110a is fluidly connected to fuel source S via high-pressure pump (S) 104 and common rail 108. The first outlet 110b is fluidly connected to the combustion chamber 32 of the internal combustion engine 10 (fig. 2). The second outlet 110c is configured to discharge a return flow F of the fuel from the injector 110.

In a particular embodiment, the injector 110 includes a housing and a piston that is movable within the housing from a first position in which the piston blocks a first outlet 110b of the injector 110 to a second position in which the piston is a distance from the first outlet 110b to allow fuel from the fuel source S to be injected into the combustion chamber 32 (fig. 2). The movement of the piston is caused by a pressure differential generated by the high pressure pump 104. When the piston moves from the first position to the second position, a portion of the fuel entering it via the inlet 110a of the injector 110 is not injected into the combustion chamber 32, but is discharged out of the injector 110 while bypassing the combustion chamber 32. The backflow F corresponds to the portion of the fuel discharged via the second outlet 110c of the fuel injector 110.

As the fuel passes through the high pressure pump(s) 104, the temperature and pressure of the fuel may increase. In use, fuel exiting the injector 110 via the second outlet 110c is typically only redirected to the fuel source S. As will be seen below, the use of a return flow F of fuel is proposed here.

The fuel injection system 102 further has a fuel circuit C comprising a main conduit 112 for supplying fuel from a fuel source S to the injector 110 and a return conduit 114 for receiving a return flow F of fuel.

The fuel circuit C may include a fuel pump 115, also referred to as a boost pump, that may be fluidly connected to the main conduit 112 and configured to draw fuel from a fuel source (e.g., fuel tank) S and direct the drawn fuel to the high-pressure pump (S) 104. Metering valve 117 may be fluidly connected to main conduit 112 upstream of high-pressure pump 104 to control the flow rate of fuel entering high-pressure pump 104. As shown, the metering valve 117 is operatively connected to the controller 105 to feed the controller 105 with data regarding the flow rate of fuel entering the high pressure fuel pump 104. The fuel filter 119 may be fluidly connected to the main conduit 112 upstream of the high pressure pump 104. In the illustrated embodiment, the fuel filter 119 is located upstream of the pump 115 with respect to the flow of fuel from the fuel source S to the high-pressure fuel pump (S) 104.

In the illustrated embodiment, the pressure regulating valve 120 is fluidly connected to the fuel circuit C. The valve 120 has an inlet 120a and an outlet 120b fluidly connectable to the inlet 120 a. The valve 120 further has a control inlet 120c, the function of which is described below.

The valve 120 has a member 120d that is movable between a closed position (as shown) and an open position (not shown). In the closed position, fuel is allowed to flow from the main fuel conduit 112 to the return conduit 114. In the open position of the member 120d, the inlet 120a of the valve 120 is fluidly connected to the outlet 120b of the valve 120. In the illustrated embodiment, in the closed position, the member 120d is biased using a biasing member 120e, which biasing member 120e may be a spring.

In the illustrated embodiment, the high pressure pump(s) 104 have a control outlet 104a, which control outlet 104a is fluidly connected to a control inlet 120c of the pressure regulating valve 120. The pressure of the fuel entering the high-pressure pump 104 from the fuel source S is preferably within a given range. If the pressure of the fuel entering the high pressure pump(s) 104 is above a given pressure threshold, the pressure at the outlet 104a is controlled to increase and push the valve 120 from the closed position to the open position, allowing fuel to flow from the main fuel conduit 112 to the return conduit 114. In other words, the pressure regulating valve 120 provides an escape path for excess fuel that would otherwise increase the inlet fuel pressure of the high pressure pump(s) 104 above a given pressure threshold.

In the illustrated embodiment, the high-pressure pump(s) 104 are fluidly connected to the injectors 110 via fuel conduits 124. Each of the injectors 110 may have its inlet 110a fluidly connected to the high pressure pump 104 via a respective one of the fuel conduits 124. In the depicted embodiment, the bypass conduit 126 is fluidly connected to the fuel conduit 124. The bypass conduit 126 may have a plurality of upstream connection points 126a, each of which is fluidly connected to a respective one of the fuel conduits 124. The bypass conduit 126 has a downstream connection point 126b that may be connected to the return conduit 114. In the illustrated embodiment, the downstream connection point 126b of the bypass conduit 126 is fluidly connected to the return conduit 114 downstream of the second outlet 110c of the ejector 110, with respect to the direction of the return flow F circulating in the return conduit.

The fuel circulating in the fuel conduit 124 between the high pressure pump 104 and the injector 110 is at a high pressure (e.g., 500 bar) and a high temperature due to having been compressed by the high pressure pump(s) 104.

In some cases, it may be advantageous to use a return flow F of fuel. Referring also to FIG. 4, the engine assembly 100 includes an injection pump 116. Jet pump 116 may be located upstream of pump 115 and downstream of filter 119. Other configurations are also contemplated. For example, the jet pump 116 may be located within the fuel tank. Jet pump 116 has motive inlet port 116a, entrainment inlet port 116b, and outlet port 116 c. The jet pump 116 may include a converging section 116d for accelerating the fuel received through the motive flow inlet 116 a.

The motive flow inlet 116a of the injection pump 116 may be connected to a second injector outlet 110c of the common rail injector 110, to a fuel conduit 124 connecting the pump 104 to the common rail injector 110, or to both the second injector outlet 110c and the fuel conduit 124.

In the illustrated embodiment, the motive flow inlet 116a is connected to a second injector outlet 110c of the common rail injector 110 and is selectively connected to the fuel conduit 124 when it is desired to increase the flow rate of fuel injected into the motive flow inlet 116 a. In the depicted embodiment, the motive flow inlet 116a may be fluidly connected to the fuel conduit 124 via the bypass conduit 126 and via the return conduit 114. Other configurations are contemplated without departing from the scope of the present disclosure.

The injection pump 116 receives a return flow F of fuel and/or a flow of fuel from a fuel line 126 fluidly connecting the high pressure pump 104 to the common rail injector 110, and injects the flow through a pipe 116 e. A tube 116e is fluidly connected to motive flow inlet 116a, to entrained flow inlet 116b, and to outlet 116 c. Injection of fuel from power flow inlet 116a into tube 116e may create a depression around the flow or jet of fuel injected through inlet 116 a. Such a depression has the suction effect of drawing the flow of fuel through entrainment flow inlet 116 b. In other words, the fuel entrains the secondary flow via the entrainment flow inlet 116b through the depression formed by the injection of the motive flow inlet 116 a. An outlet 116c of the jet pump 116, which outlet 116c is defined by a conduit 116e and may define a flow splitting section 116f, outputs a flow resulting from a combination of motive flow received via inlet 116a and entrained flow received via entrained flow inlet 116 b. Thus, the jet pump 116 can pump a fuel stream using another fuel stream from another source. In a particular embodiment, the flow splitting section 116f converts the kinetic energy of the fuel into potential energy. In certain embodiments, the disclosed system increases or improves the suction lift at the engine inlet by using the wasted energy coming out of line 110c as a motive flow. Using this normally wasted energy may allow avoiding the use of large pumps to draw fuel from the fuel tank, reducing the complexity of the system, and fully operating the system to meet the suction lift requirements at the engine inlet without the need for a pump.

The power flow generated by the return flow F of fuel and/or fuel drawn from the fuel conduit 124 may be used as a power flow source for an aircraft equipped with the disclosed engine assembly 100. For example, a motive flow source may be used to draw fuel from a fuel tank, increase the flow rate of fuel through a given fuel conduit, displace fuel from a given fuel tank to another fuel tank, and any other suitable application.

In this embodiment, flow control device 113 is fluidly connected to bypass conduit 126 between upstream connection point 126a and downstream connection point 126 b. Flow control device 113 may be a variable control orifice and may be used to vary the flow rate of fuel circulating within bypass conduit 126. The size of the orifice of the variable control orifice may be manually and/or electronically controlled to control the flow rate in the bypass conduit 126. The flow control device 113 may close fluid communication between the fuel conduit 124 and the injector 116 via the bypass conduit 126.

In certain embodiments, the disclosed fuel system allows for the use of energy from a return flow from a common rail injector or directly from a common rail fuel line to drive motive flow within an injection pump. This may allow the use of wasted energy from the common rail system to generate a pumping effect using motive flow within the low pressure fuel system or directly from the fuel tank. This concept may be applicable to all engine applications, such as turbine shafts, turboprop engines, turbofan and APU using common rail technology.

In certain embodiments, the disclosed fuel system utilizes wasted energy from common rail injectors; allows for simple power flow to replace aircraft fuel tank boost pumps to achieve lift-off; but also a low complexity system that may be lighter and less expensive than a booster pump.

To operate the aircraft engine, the fuel is pressurized for circulation by the common rail injection system 102; circulating a part of the pressurized fuel through a motive fluid inlet 116a of the jet pump 116; and entrain flow by the jet pump 116 with a portion of the pressurized fuel circulated through the motive flow inlet 116 a.

Here, a part of the pressurized fuel is a return flow F of fuel from the common rail injector 110 of the common rail fuel injection system 102. The return flow F of the fuel circulates through the motive flow inlet 116a of the jet pump 116. In the illustrated embodiment, a portion of the pressurized fuel is diverted from the at least one fuel conduit 124 to the jet pump; at least a fuel conduit 124 connects the high pressure pump 104 to the common rail injectors 110 of the common rail injection system 102.

In the illustrated embodiment, fuel is diverted from the at least one fuel conduit 124, and both the return flow F of fuel and the diverted fuel are utilized to entrain the flow. In the depicted embodiment, the injection pump 116 is fluidly connected to a fuel source S from which fuel is entrained by the injection pump 116 using a portion of the pressurized fuel.

In the illustrated embodiment, the flow rate of the diverted portion of pressurized fuel is adjusted. The adjustment of the flow rate may be achieved by restricting the flow of the diverted portion of the pressurized fuel. Here, entraining a flow with the jet pump 116 of a portion of the pressurized fuel includes entraining fuel directly from the fuel tank S.

In the illustrated embodiment, entraining a flow with a portion of the pressurized fuel via the injection pump 116 includes drawing the fuel via a main fuel conduit 112 that connects the fuel source S to the high-pressure pump 104 via the main fuel conduit 12.

To supply fuel to an aircraft engine having a common rail fuel injection system 102, the fuel is pressurized for circulation by the common rail injection system 102; injecting a portion of the fuel in a common rail injector 110 of the common rail injection system 102, thereby producing a return flow F of the fuel; and entrains fuel to be pressurized from the fuel source S by the jet pump 116 with the return flow F of fuel circulated through the motive flow inlet 116a of the jet pump 116.

In some cases, fuel is diverted from the fuel conduit 124 and both the return flow F of fuel and the diverted fuel are utilized to entrain the fuel; a fuel conduit 124 connects the high pressure pump 104 to the common rail injectors 110 of the common rail injection system 102.

In the illustrated embodiment, the flow rate of the diverted fuel is adjusted. The flow rate may be adjusted by restricting the flow of diverted fuel. In the illustrated embodiment, entraining fuel from the fuel source S via the injection pump 116 includes entraining fuel directly from the fuel tank. In the illustrated embodiment, entraining fuel from the fuel source S by the jet pump 116 includes drawing fuel through a main fuel conduit 112 that fluidly connects the fuel source S to the high pressure pump 104.

Embodiments disclosed herein include:

A. a method of operating an aircraft engine of an aircraft, the aircraft engine having a common rail fuel injection system for injecting fuel into a combustion chamber of the aircraft engine, the method comprising: pressurizing fuel for circulation by a common rail injection system; circulating a portion of the pressurized fuel through a motive flow inlet of the jet pump; and entraining the flow with the jet pump with a portion of the pressurized fuel circulated through the motive flow inlet.

B. A method of supplying fuel to an aircraft engine having a common rail fuel injection system, the method comprising: pressurizing fuel for circulation by a common rail injection system; injecting a portion of the fuel in a common rail injector of the common rail injection system, thereby generating a return flow of the fuel; and entraining fuel to be pressurized from the fuel source with the jet pump using a return flow of fuel circulated through the motive flow inlet of the jet pump.

Embodiment a and embodiment B may include any one of the following elements in any combination:

element 1: a portion of the pressurized fuel is a return flow of fuel from at least one common rail injector of a common rail fuel injection system, the method including circulating the return flow of fuel through a motive flow inlet of an injection pump. Element 2: a portion of the pressurized fuel is diverted from at least one fuel conduit to an injection pump, at least the fuel conduit connecting the high pressure pump to at least one common rail injector of a common rail injection system. Element 3: the method includes diverting fuel from at least one fuel conduit connecting a high pressure pump to at least one common rail injector of a common rail fuel injection system and entraining a flow with both the return flow of fuel and the diverted fuel. Element 4: the jet pump is fluidly connected to the fuel source, and the method includes entraining fuel from the fuel source with a portion of the pressurized fuel through the jet pump. Element 5: the flow rate of the diverted portion of the pressurized fuel is adjusted. Element 6: adjusting the flow rate includes restricting flow of the diverted portion of the pressurized fuel. Element 7: entraining a flow through the jet pump with a portion of the pressurized fuel includes entraining fuel directly from the fuel tank. Element 8: entraining the flow with a portion of the pressurized fuel with the jet pump includes drawing the fuel through a main fuel conduit fluidly connecting the fuel source to the high pressure pump.

C. An aircraft engine comprising: at least one combustion chamber; a fuel pump fluidly connected to a source of fuel; a common rail injector having an injector inlet fluidly connected to the fuel pump via a fuel conduit, a first injector outlet fluidly connected to the at least one combustion chamber, and a second injector outlet for outputting a return flow of fuel; and an ejector pump having a motive flow inlet fluidly connected to one of the second injector outlet and the fuel conduit upstream of the common rail injector and an entrainment flow inlet for receiving fuel to be drawn by the ejector pump.

Embodiment C may include any one of the following elements in any combination:

element 9: the motive flow inlet is fluidly connected to both the second injector outlet and the fuel conduit. Element 10: the motive flow inlet is fluidly connected to the fuel conduit via a bypass conduit, and the flow control device is fluidly connected to the bypass conduit. Element 11: the fuel source is a fuel tank and the injection pump is located within the fuel tank. Element 12: a main fuel conduit fluidly connects the fuel source to the fuel pump, and a booster pump fluidly connects to the main fuel conduit, the jet pump being connected to the main fuel conduit upstream of the booster pump.

The above description is merely exemplary, and those skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Other modifications which fall within the scope of the invention will be apparent to those skilled in the art upon careful study of the disclosure, and are intended to fall within the appended claims.