Fuel supply system for aircraft

Abstract

A fuel supply system for an aircraft according to the present invention comprises: an intermediate tank which is fluidly connected to a fuel pump and an engine via a fuel supply path; a pressure sensor which detects the internal pressure of the intermediate tank or a tank pressure that is correlated with the internal pressure of the intermediate tank; and a processing circuit which executes intermittent control for controlling a pump actuator in accordance with the tank pressure. The intermittent control includes: when the tank pressure increases and reaches a first threshold value, controlling the pump actuator to stop the fuel pump in a state where supply of a fuel to the engine from the intermediate tank is allowed; and when the tank pressure decreases and reaches a second threshold value which is lower than the first threshold value, controlling the pump actuator to drive the fuel pump.

Description

Aircraft fuel supply system

[0001] The present disclosure relates to an aircraft fuel supply system.

[0002] Patent Document 1 discloses a fuel supply system that supplies fuel from a fuel tank to an engine by a fuel pump in an aircraft.

[0003] Japanese Patent Application Laid-Open No. 2008-230494

[0004] The amount of fuel supplied to the engine varies greatly depending on the operating state of the aircraft. When high power is required for the engine, the fuel pump discharges fuel at a high flow rate. However, when the fuel pump operates in a low flow rate region when the output required for the engine is low, the efficiency of the fuel pump tends to deteriorate.

[0005] One aspect of the present disclosure aims to operate the fuel pump efficiently while stabilizing the fuel supply to the engine.

[0006] An aircraft fuel supply system according to one aspect of the present disclosure includes a fuel supply line that fluidly connects a fuel tank to an engine, a fuel pump that sends fuel from the fuel tank to the engine through the fuel supply line, a pump actuator that drives the fuel pump, an intermediate tank that is fluidly connected to the fuel pump and the engine via the fuel supply line, a pressure sensor that detects a tank pressure that is an internal pressure of the intermediate tank, and a processing circuit that executes intermittent control to control the pump actuator according to the tank pressure. The intermittent control includes controlling the pump actuator to stop the fuel pump in a state where fuel supply from the intermediate tank to the engine is allowed when the tank pressure increases and reaches a first threshold value, and controlling the pump actuator to drive the fuel pump when the tank pressure decreases and reaches a second threshold value that is smaller than the first threshold value.

[0007] According to one aspect of the present disclosure, it is possible to operate the fuel pump efficiently while stabilizing the fuel supply to the engine.

[0008] Figure 1 is a plan view of a hydrogen aircraft according to the first embodiment. Figure 2 is a block diagram of the fuel supply system of Figure 1. Figure 3 is a flowchart illustrating the processing of the fuel supply system of Figure 2. Figure 4 is a flowchart illustrating the intermittent control of Figure 3. Figure 5 is a timing chart illustrating the processing of the fuel supply system of Figure 2. Figure 6 is a block diagram of a first modified example of the fuel supply system of Figure 2. Figure 7 is a block diagram of a second modified example of the fuel supply system of Figure 2. Figure 8 is a block diagram of the fuel supply system according to the second embodiment. Figure 9 is a flowchart illustrating the processing of the fuel supply system of Figure 8. Figure 10 is a timing chart illustrating the processing of the fuel supply system of Figure 8.

[0009] Embodiments will be described below with reference to the drawings.

[0010] (First Embodiment) Figure 1 is a plan view of an aircraft 1 according to the first embodiment. As shown in Figure 1, the aircraft 1 comprises, for example, a fuselage 2, main wings 3, horizontal stabilizers 4, vertical stabilizers 5, and a gas turbine engine 6. The fuselage 2 extends in the longitudinal direction of the aircraft 1 and defines a crew space inside. The main wings 3 are connected to the middle of the fuselage 2 in the longitudinal direction and protrude from the fuselage 2 to the left and right of the aircraft 1. The horizontal stabilizers 4 protrude from the rear of the fuselage 2 to the left and right of the aircraft 1. The vertical stabilizers 5 protrude upward from the rear of the fuselage 2.

[0011] A gas turbine engine 6 is mounted on each of the pair of main wings 3. A fuel supply system 10 is installed on both the main wings 3 and the gas turbine engine 6. The fuel supply system 10 supplies hydrogen to the gas turbine engine 6 as fuel. Note that a fuel other than hydrogen may be used. In the following description, the gas turbine engine 6 will be simply referred to as the engine.

[0012] Figure 2 is a block diagram of the fuel supply system 10 shown in Figure 1. As shown in Figure 2, the fuel supply system 10 includes a fuel tank 11 and a fuel supply passage 12 that fluidly connects the fuel tank 11 to the engine 6. The fuel tank 11 stores liquefied hydrogen as hydrogen fuel. The fuel tank 11 is mounted on the fuselage 2 or the main wing 3. The fuel supply passage 12 guides the hydrogen fuel from the fuel tank 11 to the combustor of the engine 6. The fuel supply passage 12 is, for example, a pipe passage.

[0013] The fuel supply passage 12 includes a main passage 12a that fluidly connects the fuel tank 11 to the engine 6, and a secondary passage 12b that branches off from the main passage 12a. A fuel pump 13 is located in the main passage 12a. The fuel pump 13 is preferably a turbopump suitable for intermittent operation, as described later. The fuel pump 13 is driven by a pump actuator 14. The pump actuator 14 includes an electric motor. The fuel pump 13 pressurizes and delivers liquefied hydrogen from the main passage 12a of the fuel supply passage 12 toward the engine 6. A booster pump may be located between the fuel tank 11 and the fuel pump 13 in the main passage 12a. The booster pump is a pump for pressurizing hydrogen fuel from the fuel tank 11 to the fuel pump 13.

[0014] In the main flow path 12a of the fuel supply passage 12, a heat exchanger 16 is located downstream of the fuel pump 13. Liquefied hydrogen flowing from the fuel pump 13 into the heat exchanger 16 is heated by the heat exchanger 16 and converted into hydrogen gas. In the main flow path 12a of the fuel supply passage 12, a fuel supply valve 15 is located between the heat exchanger 16 and the engine 6. By changing the opening degree of the fuel supply valve 15, the flow rate of hydrogen gas supplied to the combustor of the engine 6 is changed.

[0015] The sub-channel 12b of the fuel supply passage 12 branches off from branching point Z, which is the section between the fuel pump 13 and the heat exchanger 16 in the main passage 12a. An intermediate tank 17 is fluidly connected to the sub-channel 12b. Since liquefied hydrogen is supplied to the intermediate tank 17 from the fuel pump 13, the intermediate tank 17 can function as an accumulator with a variable volume. The intermediate tank 17 can appropriately absorb fluctuations in the flow rate of hydrogen fuel supplied to the engine 6.

[0016] The shape of the intermediate tank 17 is not particularly limited as long as it has sufficient volume. If the direction in which the flow path axis of the end of the sub-flow channel 12b connected to the intermediate tank 17 extends is defined as the flow path axis direction D, then the volume of the intermediate tank 17 per unit length in the flow path axis direction D is greater than the volume of the sub-flow channel 12b per unit length in the flow path axis direction D. With respect to a cross section perpendicular to the flow path axis direction D, the intermediate tank 17 includes a portion having a cross-sectional area larger than the maximum cross-sectional area of ​​the sub-flow channel 12b.

[0017] The sub-flow channel 12b may also be branched from the portion of the main flow channel 12a between the heat exchanger 16 and the fuel supply valve 15. In that case, since hydrogen gas is introduced to the intermediate tank 17 from the heat exchanger 16, the intermediate tank 17 may be a tank with a fixed volume or an accumulator.

[0018] A control valve 18 is located in the sub-flow channel 12b between the main flow channel 12a and the intermediate tank 17. The control valve 18 may be a valve whose opening degree can be adjusted, but it may also simply be a valve that opens and closes the flow channel. The control valve 18 is a valve that can shut off the flow from the fuel pump 13 to the intermediate tank 17 via the sub-flow channel 12b. The intermediate tank 17 is fluidically connected to the fuel pump 13 and the engine 6 via the fuel supply passage 12. Specifically, the intermediate tank 17 is fluidically connected to the fuel pump 13 when the control valve 18 is open. The intermediate tank 17 is fluidly connected to the engine 6 when the control valve 18 and the fuel supply valve 15 are open.

[0019] A check valve 19 is positioned between the branching point Z where the sub-flow path 12b intersects the main flow path 12a and the fuel pump 13. The check valve 19 blocks the flow from the heat exchanger 16 and intermediate tank 17 toward the fuel pump 13, while allowing the flow from the fuel pump 13 toward the heat exchanger 16 and intermediate tank 17.

[0020] A pressure sensor 20 is provided in the sub-flow channel 12b of the fuel supply passage 12 to detect the internal pressure of the intermediate tank 17 or the tank pressure, which is a pressure correlated with the internal pressure of the intermediate tank 17. The detection unit of the pressure sensor 20 may be located in the intermediate tank 17 or in the sub-flow channel 12b. The detection unit of the pressure sensor 20 may also be located in the portion of the sub-flow channel 12b between the control valve 18 and the intermediate tank 17. In addition, the engine 6 is provided with an engine speed sensor 25 to detect the rotational speed of the engine 6.

[0021] The fuel supply line 12 is provided with a temperature sensor 21 that detects the temperature of the portion of the fuel supply line 12 between the fuel tank 11 and the heat exchanger 16. The temperature sensor 21 only needs to be able to detect a temperature that correlates with the temperature of the liquid phase hydrogen fuel flowing through the fuel supply line 12, and the location of the temperature sensor 21 is not particularly limited. In this embodiment, it is preferable that the temperature sensor 21 be positioned to detect the temperature of the portion of the fuel supply line 12 between the branching point Z and the heat exchanger 16.

[0022] The fuel supply system 10 includes a controller 22. The controller 22 includes a processing circuit 23. Specifically, the controller 22 includes a processor and memory. The processor includes, for example, a CPU (Central Processing Unit). The memory includes, for example, system memory and storage memory. The system memory includes, for example, volatile memory. The storage memory includes, for example, non-volatile memory. The storage memory may include, for example, a hard disk, flash memory, or a combination thereof. The storage memory stores a control program. An example of a configuration in which the processor executes a control program read from the system memory is the processing circuit 23.

[0023] The processing circuit 23 receives detection signals from the output request sensor 24, pressure sensor 20, temperature sensor 21, and engine rotation speed sensor 25. The output request sensor 24 detects the output command value input from the pilot of the aircraft 1. The output command value means the value of the output that the pilot requests from the engine 6. The output request sensor 24 detects, for example, the angle of the throttle lever operated by the pilot. The processing circuit 23 controls the fuel supply valve 15 to adjust the opening degree of the fuel supply valve 15 according to the output command value detected by the output request sensor 24. The processing circuit 23 controls the pump actuator 14 according to the output command value detected by the output request sensor 24. The processing circuit 23 controls the regulating valve 18 according to the tank pressure detected by the pressure sensor 20. The processing circuit 23 controls the pump actuator 14 according to the temperature detected by the temperature sensor 21.

[0024] Figure 3 is a flowchart illustrating the process of the fuel supply system 10 in Figure 2. Figure 4 is a flowchart illustrating the intermittent control in Figure 3. Figure 5 is a timing chart illustrating the process of the fuel supply system 10 in Figure 2. The process of the fuel supply system 10 will be explained below following the flow shown in Figures 3 and 4, with reference to Figure 5.

[0025] In step S1 of Figure 3, the processing circuit 23 acquires the output command value from the output request sensor 24 as the output-related value. The output-related value is a value that increases or decreases the output of the engine 6 in accordance with the output-related value. For example, the output-related value may be a value in which the output of the engine 6 increases when the output-related value increases and decreases when the output-related value decreases, or it may be a value in which the output of the engine 6 increases or decreases in proportion to the output-related value. Instead of the output command value, the output-related value may be, for example, the flow rate of hydrogen gas supplied to the engine 6 from the fuel supply valve 15, or the rotational speed of the engine 6.

[0026] In step S2, the processing circuit 23 determines whether the output command value is less than a predetermined value X. If it is determined that the output command value is less than the predetermined value X, in step S3, the processing circuit 23 opens the control valve 18. Then, in step S4, the processing circuit 23 performs intermittent control with the control valve 18 open. As shown in Figure 5, intermittent control is performed when the aircraft 1 is taxiing before takeoff because the output command value is less than the predetermined value X. In intermittent control, the processing circuit 23 controls the pump actuator 14 according to the tank pressure detected by the pressure sensor 20.

[0027] Details of the intermittent control are shown in the flowchart of Figure 4. In step S11, the processing circuit 23 controls the pump actuator 14 to drive the fuel pump 13. When the fuel pump 13 is driven in intermittent control, the processing circuit 23 controls the pump actuator 14 so that the rotational speed of the fuel pump 13 is maintained at or above a predetermined value R. The predetermined value R is a value greater than zero. The rotational speed of the fuel pump 13 may be detected by a rotational speed sensor or calculated based on a control signal to the pump actuator 14.

[0028] In the example shown in Figure 5, when the fuel pump 13 is driven in intermittent control mode, the pump actuator 14 is controlled so that the discharge pressure of the fuel pump 13 increases when the rotational speed of the fuel pump 13 is above a predetermined value R. As a result, the fuel pump 13 does not operate in the low flow rate range in intermittent control mode, and the efficiency of the fuel pump 13 is maintained well.

[0029] Furthermore, if the fuel supply system 10 is equipped with a flow sensor for detecting the flow rate of the fuel pump 13, the processing circuit 23 may control the pump actuator 14 based on the detection signal from the flow sensor so that the flow rate of the fuel pump 13 is maintained at or above a predetermined value while the fuel pump 13 is driven during intermittent control.

[0030] In step S12, the processing circuit 23 determines whether the tank pressure detected by the pressure sensor 20 has increased and reached a predetermined first threshold Y1. For example, the first threshold Y1 is set to a large value within a range that does not reach the upper limit of pressure that is permissible for the intermediate tank 17 in terms of pressure resistance. If it is determined that the tank pressure has not reached the first threshold Y1, the processing circuit 23 controls the pump actuator 14 to continue driving the fuel pump 13. If it is determined that the tank pressure has reached the first threshold Y1, in step S13, the processing circuit 23 controls the pump actuator 14 to stop the fuel pump 13. Note that when the fuel pump 13 is stopped, it means that it is not being driven by the pump actuator 14, so the rotating element of the stopped fuel pump 13 may passively rotate due to the flow of hydrogen fuel.

[0031] In step S14, the processing circuit 23 determines whether the tank pressure detected by the pressure sensor 20 has decreased to a predetermined second threshold Y2 while the fuel pump 13 is stopped. The second threshold Y2 is smaller than the first threshold Y1. For example, the second threshold Y2 is set to a value that is smaller than the first threshold Y1 and larger than the pressure required to supply hydrogen fuel to the fuel supply valve 15. If it is determined that the tank pressure has reached the second threshold Y2, in step S11, the processing circuit 23 controls the pump actuator 14 to drive the fuel pump 13.

[0032] In intermittent control, the fuel pump 13 repeatedly switches between being driven and stopped. When the fuel pump 13 is driven in intermittent control, hydrogen fuel is supplied from the fuel pump 13 to the intermediate tank 17, and hydrogen fuel is also supplied from the fuel pump 13 to the engine 6 via the fuel supply valve 15. When the fuel pump 13 is stopped in intermittent control, hydrogen fuel is supplied from the intermediate tank 17 to the engine 6 via the fuel supply valve 15.

[0033] If, during intermittent control, the output command value is determined to be greater than or equal to a predetermined value X in step S2 of Figure 3, the processing circuit 23 executes non-intermittent control in step S5. As shown in Figure 5, during takeoff and climb after taxiing of the aircraft 1, the output command value is greater than or equal to the predetermined value X, so non-intermittent control, i.e., normal control, is executed. In non-intermittent control, the processing circuit 23 controls the pump actuator 14 according to the output command value to drive the fuel pump 13. The processing circuit 23 performs feedback control so that the rotational speed of the engine 6 detected by the engine rotational speed sensor 25 approaches the rotational speed corresponding to the output command value.

[0034] When aircraft 1 transitions from taxiing to takeoff, the discharge pressure of fuel pump 13 increases in accordance with the increase in the output command value. When transitioning from intermittent control to non-intermittent control, with the control valve 18 open, the hydrogen fuel discharged from fuel pump 13 flows towards both engine 6 and intermediate tank 17. Therefore, the discharge amount of fuel pump 13 becomes greater than the amount of fuel required by engine 6.

[0035] In step S6, the processing circuit 23 determines whether the tank pressure detected by the pressure sensor 20 has increased and reached the first threshold Y1. If it is determined that the tank pressure has not reached the first threshold Y1, in step S8, the processing circuit 23 opens the regulating valve 18. On the other hand, if it is determined that the tank pressure has reached the first threshold Y1, in step S7, the processing circuit 23 closes the regulating valve 18. When the regulating valve 18 is closed, the fuel pump 13 no longer needs to discharge fuel to supply to the intermediate tank 17. Therefore, at the time the regulating valve 18 is closed, the discharge amount of the fuel pump 13 is adjusted by the feedback control to match the amount of fuel required by the engine 6.

[0036] During the cruise phase after the aircraft 1 ascends, the output command value is greater than or equal to a predetermined value X and remains constant, and the feedback control continues according to this constant output command value. During the descent phase after the aircraft 1 cruises, in step S2, the output command value is determined to be less than the predetermined value X, so with the control valve 18 open, the processing circuit 23 performs intermittent control. The intermittent control during the descent of the aircraft 1 is the same as the intermittent control during the taxiing of the aircraft 1. In intermittent control, the processing circuit 23 controls the pump actuator 14 based on the tank pressure detected by the pressure sensor 20 instead of the output command value.

[0037] During the cruise phase before the aircraft 1 descends, the control valve 18 is closed when the tank pressure reaches the first threshold Y1. Therefore, when the aircraft 1 transitions from the cruise state to the descending state, the control valve 18 opens, and hydrogen fuel is rapidly supplied from the intermediate tank 17 to the engine 6. In this way, in the initial stage of intermittent control immediately following non-intermittent control, hydrogen fuel from the intermediate tank 17, which is kept at high pressure, is rapidly supplied to the engine 6.

[0038] During landing after the descent of aircraft 1, the output command value becomes greater than or equal to a predetermined value X, so intermittent control is performed in step S5. The intermittent control during landing of aircraft 1 is the same as the intermittent control during takeoff of aircraft 1. During taxiing after landing of aircraft 1, the output command value becomes less than the predetermined value X, so intermittent control is performed in step S4. The intermittent control after landing of aircraft 1 is the same as the intermittent control before takeoff of aircraft 1.

[0039] According to the configuration described above, when the output required by the engine 6 is low, the fuel pump 13 operates intermittently through intermittent control to keep the pressure in the intermediate tank 17 within an appropriate range. Therefore, while stably supplying hydrogen fuel to the engine 6, the fuel pump 13 does not need to be operated at a low flow rate, and the fuel pump 13 can be operated efficiently.

[0040] In Figure 2, an example was shown in which the control valve 18 allows flow in both directions: from the branching point Z towards the intermediate tank 17 and from the intermediate tank 17 towards the branching point Z. However, modified examples such as those shown in Figure 6 or Figure 7 may also be adopted.

[0041] Figure 6 is a block diagram of a first modified example of the fuel supply system 10 of Figure 2. As shown in Figure 6, in the first modified example, the fuel supply passage 12 includes a first sub-passage 12c that branches off from a first branching point Z1 between the fuel pump 13 and the heat exchanger 16 in the main passage 12a, and a second sub-passage 12d that branches off from a second branching point Z2 between the fuel pump 13 and the heat exchanger 16 in the main passage 12a. The first sub-passage 12c and the second sub-passage 12d are connected to an intermediate tank 17. A first control valve 18A is located in the portion of the first sub-passage 12c between the first branching point Z1 and the intermediate tank 17. A second control valve 18B is located in the portion of the second sub-passage 12d between the second branching point Z2 and the intermediate tank 17.

[0042] The first sub-flow channel 12c may be provided with a first check valve 26A that allows flow from the first branching point Z1 to the intermediate tank 17 and blocks flow from the intermediate tank 17 to the first branching point Z1. The second sub-flow channel 12d may be provided with a second check valve 26B that allows flow from the intermediate tank 17 to the second branching point Z2 and blocks flow from the second branching point Z2 to the intermediate tank 17. The first check valve 26A may be positioned between the first branching point Z1 and the first control valve 18A, or between the first control valve 18A and the intermediate tank 17. The second check valve 26B may be positioned between the second branching point Z2 and the second control valve 18B, or between the second control valve 18B and the intermediate tank 17.

[0043] Further, the first and second regulating valves 18A and 18B may be configured to allow flow in only one direction. In this case, fuel flows from the first branch point Z1 to the intermediate tank 17 in the first sub-flow path 12c with the first regulating valve 18A open, and fuel flows from the intermediate tank 17 to the second branch point Z2 in the second sub-flow path 12d with the second regulating valve 18B open. When the first and second regulating valves 18A and 18B are valves that allow flow in only one direction in this way, the first check valve 26A and the second check valve 26B can be omitted.

[0044] The first regulating valve 18A and the second regulating valve 18B may be controlled in the same manner as the regulating valve 18 in FIG. 2. That is, the first regulating valve 18A and the second regulating valve 18B may open and close in synchronization with each other. Alternatively, the first regulating valve 18A and the second regulating valve 18B may open and close at different times.

[0045] FIG. 7 is a block diagram of a second modification of the fuel supply system 10 of FIG. 2. As shown in FIG. 7, in the second modification, the fuel supply path 12 includes a first sub-flow path 12e branched from a first branch point Z3 between the fuel pump 13 and the heat exchanger 16 in the main flow path 12a, and a second sub-flow path 12f branched from a second branch point Z4 between the fuel tank 11 and the fuel pump 13 in the main flow path 12a. The first sub-flow path 12e and the second sub-flow path 12f are connected to the intermediate tank 17. A first regulating valve 18C is disposed in a portion between the first branch point Z3 and the intermediate tank 17 in the first sub-flow path 12e. A second regulating valve 18D is disposed in a portion between the second branch point Z4 and the intermediate tank 17 in the second sub-flow path 12f.

[0046] A first check valve 26C that allows the flow from the first branch point Z3 to the intermediate tank 17 and blocks the flow from the intermediate tank 17 to the first branch point Z3 may be provided in the first sub-flow path 12e. A second check valve 26D that allows the flow from the intermediate tank 17 to the second branch point Z4 and blocks the flow from the second branch point Z4 to the intermediate tank 17 may be provided in the second sub-flow path 12f. The first check valve 26C may be arranged between the first branch point Z3 and the first regulating valve 18C, or between the first regulating valve 18C and the intermediate tank 17. The second check valve 26D may be arranged between the second branch point Z4 and the second regulating valve 18D, or between the second regulating valve 18D and the intermediate tank 17.

[0047] In addition, the first and second regulating valves 18C and 18D may be configured to allow flow in only one direction. In this case, when the first regulating valve 18C is open, fuel flows from the first branch point Z3 to the intermediate tank 17 in the first sub-flow path 12e, and when the second regulating valve 18D is open, fuel flows from the intermediate tank 17 to the second branch point Z4 in the second sub-flow path 12f. When the first and second regulating valves 18C and 18D are valves that allow flow in only one direction as described above, the first check valve 26C and the second check valve 26D can be omitted. The first regulating valve 18C and the second regulating valve 18D may be controlled in the same manner as the regulating valve 18 in FIG. 2. That is, the first regulating valve 18C and the second regulating valve 18D may open and close at the same time. The first regulating valve 18C and the second regulating valve 18D may open and close at different times.

[0048] In the configuration of FIG. 7, in intermittent control, when hydrogen fuel is supplied from the intermediate tank 17 to the engine 6 while the pump actuator 14 is not driven, the hydrogen fuel passes through the fuel pump 13, and the fuel pump 13 and the like can be kept at a low temperature.

[0049] (Second Embodiment) Figure 8 is a block diagram of the fuel supply system 110 according to the second embodiment. Components common to the first embodiment are denoted by the same reference numerals and their descriptions are omitted. As shown in Figure 8, in the fuel supply system 110, the intermediate tank 17 is arranged in series between the fuel pump 13 and the heat exchanger 16 in the fuel supply passage 112 that fluidly connects the fuel tank 11 to the engine 6. Since liquid-phase hydrogen is supplied to the intermediate tank 17 from the fuel pump 13, the intermediate tank 17 can function as an accumulator with a changing volume.

[0050] The intermediate tank 17 may be located between the heat exchanger 16 and the fuel supply valve 15 in the fuel supply passage 112. In that case, since gaseous hydrogen is introduced into the intermediate tank 17 from the heat exchanger 16, the intermediate tank 17 may be a tank with a fixed volume or an accumulator.

[0051] The processing circuit 123 of the controller 122 controls the pump actuator 14 and the fuel supply valve 15 based on detection signals from the output request sensor 24, pressure sensor 20, temperature sensor 21, and engine rotation speed sensor 25.

[0052] Figure 9 is a flowchart illustrating the processing of the fuel supply system 110 in Figure 8. Figure 10 is a timing chart illustrating the processing of the fuel supply system 110 in Figure 8. Hereinafter, the processing of the fuel supply system 110 will be explained following the flow in Figure 9 with reference to Figure 10. In step S21 of Figure 9, the processing circuit 123 acquires the output command value from the output request sensor 24 as an output-related value.

[0053] In step S22, the processing circuit 123 determines whether the output command value is less than a predetermined value X. If it is determined that the output command value is less than the predetermined value X, in step S23, the processing circuit 123 executes intermittent control. As shown in Figure 8, intermittent control is executed during taxiing before the aircraft takes off because the output command value is less than the predetermined value X. The intermittent control in the second embodiment is the same as the intermittent control in the first embodiment.

[0054] In intermittent control, the processing circuit 123 controls the pump actuator 14 to drive the fuel pump 13 when it determines that the tank pressure detected by the pressure sensor 20 has not reached the first threshold Y1, while controlling the pump actuator 14 to stop the fuel pump 13 when it determines that the tank pressure detected by the pressure sensor 20 has reached the first threshold Y1. When the fuel pump 13 is driven in intermittent control, the rotational speed of the fuel pump 13 is maintained at or above a predetermined value R. Since the intermediate tank 17 is arranged in series between the fuel pump 13 and the heat exchanger 16, the hydrogen fuel discharged from the fuel pump 13 is guided to the engine 6 via the intermediate tank 17.

[0055] If, during intermittent control, the output command value is determined to be greater than or equal to a predetermined value X in step S22 of Figure 7, the processing circuit 123 executes non-intermittent control in step S24. As shown in Figure 8, during takeoff and climb after the aircraft has taxied, the output command value is greater than or equal to the predetermined value X, so non-intermittent control, i.e., normal control, is executed. In non-intermittent control, the processing circuit 123 controls the pump actuator 14 to drive the fuel pump 13 according to the output command value. The processing circuit 123 performs feedback control so that the rotational speed of the engine 6 detected by the engine rotational speed sensor 25 approaches the rotational speed corresponding to the output command value. Non-intermittent control is similarly executed during cruising after the aircraft has climbed.

[0056] During the descent of the aircraft after cruising, the output command value is determined to be less than the predetermined value X in step S22, so in step S23, the processing circuit 23 performs intermittent control. During landing after the aircraft's descent, the output command value becomes greater than or equal to the predetermined value X, so in step S24, non-intermittent control is performed. During taxiing after the aircraft's landing, the output command value becomes less than the predetermined value X, so in step S23, intermittent control is performed. Note that the other configurations are the same as those of the first embodiment described above, so their explanation is omitted.

[0057] The technology disclosed herein is not limited to the embodiments described above. For example, the pump actuator 14 is not limited to an electric motor. The pump actuator 14 may be a device that includes a continuously variable transmission that changes the power extracted from the engine 6 to a target rotational speed, a power path that transmits the power output from the continuously variable transmission to the fuel pump 13, and a clutch interposed in the power path.

[0058] As described above, the embodiments have been explained as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to the embodiments described above and can be applied to embodiments that have been modified, replaced, added, or omitted as appropriate. Furthermore, it is possible to combine the components described in the embodiments to create new embodiments. For example, some components or methods in one embodiment may be applied to other embodiments, and some components in an embodiment can be separated from other components in that embodiment and extracted as appropriate. In addition, the components described in the attached drawings and detailed description include not only components that are essential for solving the problem, but also components that are not essential for solving the problem, in order to illustrate the technology.

[0059] The functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, dedicated processors, integrated circuits, ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuits. In this disclosure, a circuit, unit, or means is hardware that performs the enumerated functions, or hardware programmed to perform the enumerated functions. The hardware may be hardware disclosed herein, or other known hardware that is programmed or configured to perform the enumerated functions. If the hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or the processor.

[0060] [Embodiment] The embodiments described above are specific examples of the following embodiments.

[0061] (Aspect 1) An aircraft fuel supply system comprising: a fuel supply passage that fluidly connects a fuel tank to an engine; a fuel pump that supplies fuel from the fuel tank to the engine through the fuel supply passage; a pump actuator that drives the fuel pump; an intermediate tank that fluidly connects the fuel pump and the engine via the fuel supply passage; a pressure sensor that detects the internal pressure of the intermediate tank or a tank pressure that is correlated with the internal pressure of the intermediate tank; and a processing circuit that performs intermittent control to control the pump actuator according to the tank pressure, wherein the intermittent control includes: when the tank pressure increases and reaches a first threshold, controlling the pump actuator to stop the fuel pump while allowing fuel to be supplied from the intermediate tank to the engine; and when the tank pressure decreases and reaches a second threshold smaller than the first threshold, controlling the pump actuator to drive the fuel pump.

[0062] According to Embodiment 1, fluctuations in the fuel flow rate supplied to the engine are appropriately absorbed by the intermediate tank, thereby stabilizing the fuel supply to the engine. Furthermore, since the fuel pump operates intermittently to keep the pressure in the intermediate tank within an appropriate range, it is not necessary to operate the fuel pump at a low flow rate. Thus, the fuel pump can be operated efficiently while stabilizing the fuel supply to the engine.

[0063] (Aspect 2) The aircraft fuel supply system according to aspect 1, wherein the processing circuit acquires an output-related value correlated with the output of the engine, performs non-intermittent control to drive the fuel pump by controlling the pump actuator according to the output-related value of the engine when the output-related value is greater than or equal to a predetermined value, and performs the intermittent control when the output-related value is less than the predetermined value.

[0064] According to embodiment 2, when the output required from the engine is high, the fuel pump supplies fuel to the engine at a high flow rate, while when the output required from the engine is low, the fuel pump operates intermittently within a range where the pressure in the intermediate tank does not become low, thus eliminating the need to operate the fuel pump at a low flow rate.

[0065] (Aspect 3) The fuel supply passage includes a main passage through which the fuel pump is located, with the fuel tank being fluidly connected to the engine, and at least one sub-passage fluidly connected to the main passage to the intermediate tank, the fuel supply system further comprises a valve in the sub-passage capable of blocking the flow between the intermediate tank and the main passage, and in the intermittent control, the processing circuit includes controlling the valve to keep it open, the aircraft fuel supply system according to aspect 1 or 2.

[0066] According to embodiment 3, in a configuration in which the fuel supply passage has a main passage and a sub-passage, by maintaining the valve in an open state, it is possible to easily supply fuel from the intermediate tank to the engine, supply fuel from the fuel pump to the intermediate tank, and supply fuel from the fuel pump to the engine.

[0067] (Aspect 4) The fuel supply passage includes a main passage through which the fuel pump is located, with the fuel tank being fluidly connected to the engine, and at least one sub-passage fluidly connected to the main passage to the intermediate tank, the fuel supply system further comprises a valve in the sub-passage capable of blocking the flow between the intermediate tank and the main passage, and in the non-intermittent control, the processing circuit controls the valve to close it when the tank pressure increases and reaches the first threshold, the aircraft fuel supply system according to aspect 2 or 3.

[0068] According to embodiment 4, fuel can be quickly supplied from the intermediate tank to the engine during the initial stage of intermittent control immediately following non-intermittent control.

[0069] (Aspect 5) The aircraft fuel supply system according to any one of aspects 1 to 4, wherein the intermediate tank is arranged in series with respect to the portion of the fuel supply line between the fuel pump and the engine.

[0070] This configuration allows for a simplified structure.

[0071] (Aspect 6) In the intermittent control, the processing circuit controls the pump actuator to drive the fuel pump so that the flow rate or rotational speed of the fuel pump is maintained at or above a predetermined value when the tank pressure reaches the second threshold, the aircraft fuel supply system according to any one of aspects 1 to 5.

[0072] With this configuration, the fuel pump does not operate in the low flow rate range during intermittent control, thus maintaining good fuel pump efficiency.

[0073] 1. Aircraft 6. Engine 10, 110. Fuel supply system 11. Fuel tank 12, 112. Fuel supply passage 12a. Main passage 12b. Sub-passage 12c, 12e. First sub-passage 12d, 12f. Second sub-passage 13. Fuel pump 14. Pump actuator 15. Fuel supply valve 16. Heat exchanger 17. Intermediate tank 18. Control valve 18A, 18C. First control valve 18B, 18D. Second control valve 20. Pressure sensor 21. Temperature sensor 22, 122. Controller 23, 123. Processing circuit

Claims

1. An aircraft fuel supply system comprising: a fuel supply passage that fluidly connects a fuel tank to an engine; a fuel pump that delivers fuel from the fuel tank to the engine through the fuel supply passage; a pump actuator that drives the fuel pump; an intermediate tank that fluidly connects the fuel pump and the engine via the fuel supply passage; a pressure sensor that detects the internal pressure of the intermediate tank or a tank pressure that is correlated with the internal pressure of the intermediate tank; and a processing circuit that performs intermittent control to control the pump actuator according to the tank pressure, wherein the intermittent control includes: controlling the pump actuator to stop the fuel pump when the tank pressure increases and reaches a first threshold, while allowing fuel to be supplied from the intermediate tank to the engine; and controlling the pump actuator to drive the fuel pump when the tank pressure decreases and reaches a second threshold smaller than the first threshold.

2. The aircraft fuel supply system according to claim 1, wherein the processing circuit obtains an output-related value correlated with the output of the engine, performs non-intermittent control to drive the fuel pump by controlling the pump actuator according to the output-related value of the engine when the output-related value is greater than or equal to a predetermined value, and performs the intermittent control when the output-related value is less than the predetermined value.

3. The fuel supply passage includes a main passage through which the fuel pump is located, with the fuel tank being fluidly connected to the engine, and at least one sub-passage fluidly connected to the main passage to the intermediate tank, the fuel supply system further comprises a valve in the sub-passage capable of blocking the flow between the intermediate tank and the main passage, and in the intermittent control, the processing circuit includes controlling the valve to keep it open, the aircraft fuel supply system according to claim 1 or 2.

4. The fuel supply passage includes a main passage through which the fuel pump is located, with the fuel tank being fluidly connected to the engine, and at least one sub-passage fluidly connected to the main passage to the intermediate tank, the fuel supply system further comprises a valve in the sub-passage capable of blocking the flow between the intermediate tank and the main passage, and in the non-intermittent control, the processing circuit controls the valve to close it when the tank pressure increases to the first threshold.

5. The aircraft fuel supply system according to claim 1 or 2, wherein the intermediate tank is arranged in series with respect to the portion of the fuel supply line between the fuel pump and the engine.

6. In the intermittent control, the processing circuit controls the pump actuator to drive the fuel pump so that the flow rate or rotational speed of the fuel pump is maintained at or above a predetermined value when the tank pressure reaches the second threshold, according to the aircraft fuel supply system according to claim 1 or 2.

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