Fuel system of auxiliary power device, control method of fuel system and airplane

Abstract

The invention discloses a fuel oil system of an auxiliary power device, a control method of the fuel oil system and an airplane. A fuel oil module of the fuel oil system transmits fuel oil to a first stop valve, a second stop valve and a third stop valve through transmission pipelines; the controller controls a fuel pump of the fuel module to rotate; the pre-combustion stage nozzle comprises a first nozzle channel and a second nozzle channel; the first stop valve transmits fuel oil to the first nozzle channel through a first fuel oil main pipe; the second stop valve transmits fuel oil to the second nozzle channel through a second fuel oil main pipe. The third stop valve transmits fuel oil to the main combustion stage nozzle through a third fuel oil main pipe; the controller controls the first stop valve and / or the second stop valve to be switched on, so that the fuel oil supply amount transmitted to the pre-combustion stage nozzle by the fuel oil module is the ignition fuel oil amount; the controller further controls the third stop valve to be switched on so that the third fuel oil main pipe can transmit fuel oil to the main combustion stage nozzle. According to the technical scheme, it is guaranteed that the auxiliary power device is successfully started at high altitude.

Description

Technical Field

[0001] The present invention relates to the field of flight technology, and in particular to a fuel system of an auxiliary power device and a control method thereof, and an aircraft. Background Art

[0002] Auxiliary power unit refers to the airborne power unit other than the main power unit on aircrafts such as airplanes, which is generally a small gas turbine engine. Its main functions are to provide compressed air for starting the main engine, providing compressed air for the aircraft environmental control system, providing ground power for the aircraft power system, and providing backup power after the main engine of the aircraft fails. Auxiliary power units are now equipped in all aircrafts, and their importance is becoming more and more prominent.

[0003] Modern aircraft are flying at higher and higher altitudes. When the main power unit of an aircraft stops in the air at high altitude, the auxiliary power unit needs to be started up in an emergency to ensure the power supply of the aircraft and restart the main power unit. Therefore, the high-altitude starting performance of the auxiliary power unit is directly related to the safety of the aircraft. However, the existing auxiliary power unit has poor high-altitude starting performance, and there is a risk of failure of the auxiliary power system to start at high altitude. Summary of the invention

[0004] The embodiment of the present invention provides a fuel system of an auxiliary power unit and a control method thereof, and an aircraft, so as to ensure that the auxiliary power unit is successfully started at high altitude.

[0005] In a first aspect, an embodiment of the present invention provides a fuel system for an auxiliary power unit, comprising: a controller, a fuel module, a first stop valve, a second stop valve, a third stop valve, a pre-combustion stage nozzle, and a main combustion stage nozzle;

[0006] The fuel module is used to pressurize the fuel in the fuel inlet and transmit it to the first stop valve, the second stop valve and the third stop valve through the transmission pipeline respectively; the controller is electrically connected to the fuel module and is used to control the rotation of the fuel pump of the fuel module;

[0007] The pre-combustion stage nozzle comprises a first nozzle channel and a second nozzle channel; the first shut-off valve transmits fuel to the first nozzle channel through a first fuel main pipe; the second shut-off valve transmits fuel to the second nozzle channel through a second fuel main pipe; the third shut-off valve transmits fuel to the main combustion stage nozzle through a third fuel main pipe;

[0008] The controller is electrically connected to the first stop valve and the second stop valve respectively, and is used to control the conduction of the first stop valve and / or the second stop valve so that the fuel supply amount transmitted by the fuel module to the pre-combustion stage nozzle is the ignition fuel amount of the auxiliary power unit; the controller is also electrically connected to the third stop valve, and is used to control the conduction of the third stop valve so that the third fuel main pipe transmits fuel to the main combustion stage nozzle.

[0009] In a second aspect, an embodiment of the present invention further provides a control method for a fuel system of an auxiliary power device, which is applicable to the fuel system of an auxiliary power device provided by any embodiment of the present invention, and includes:

[0010] The controller obtains a start-up instruction of the auxiliary power unit, and controls the rotation of the fuel pump of the fuel module according to the start-up instruction, so that the fuel module transmits fuel to the transmission pipeline;

[0011] During the ignition phase of the auxiliary power unit, the controller controls the first shut-off valve and / or the second shut-off valve to be turned on, so that the fuel supply amount transmitted by the fuel module to the pre-combustion stage nozzle is the ignition fuel amount of the auxiliary power unit;

[0012] During the operation phase of the auxiliary power unit, the controller controls the third shut-off valve to be turned on, so that the third fuel main pipe transmits fuel to the main combustion stage nozzle.

[0013] In a third aspect, an embodiment of the present invention further provides an aircraft, comprising: an auxiliary power unit; and a fuel system of the auxiliary power unit provided by any embodiment of the present invention.

[0014] In the present invention, in the fuel system of the auxiliary power unit, the fuel pump of the fuel module rotates under the control of the controller, and the fuel at the fuel inlet is pressurized and transmitted to the transmission pipeline. The output end of the transmission pipeline is connected to the first fuel main pipe through the first stop valve to transmit the fuel to the first nozzle channel of the pre-combustion stage nozzle; the output end of the transmission pipeline is connected to the second fuel main pipe through the second stop valve to transmit the fuel to the second nozzle channel of the pre-combustion stage nozzle; the output end of the transmission pipeline is connected to the third fuel main pipe through the third stop valve to transmit the fuel to the main combustion stage nozzle. The controller can control the conduction and shutoff of the first stop valve, the second stop valve and the third stop valve respectively. Specifically, by controlling the conduction of the first stop valve and / or the second stop valve, the fuel supply amount of the pre-combustion stage nozzle is the ignition fuel amount, and by controlling the conduction of the third stop valve, the fuel is transmitted to the main combustion stage nozzle. During the ignition stage of the fuel system, because the amount of ignition fuel for the auxiliary power unit at high altitude is extremely small, this embodiment controls the fuel supply to the pre-combustion stage nozzle by opening or closing the first stop valve and the second stop valve, so that the fuel supply is exactly the ignition fuel amount and does not exceed the amount, thereby ensuring the successful ignition of the auxiliary power unit at high altitude, being compatible with the large fuel demand of the auxiliary power unit, and expanding the use envelope of the auxiliary power unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the structure of a fuel system of an auxiliary power unit provided by an embodiment of the present invention;

[0016] Figure 2 A schematic diagram of the structure of a pre-combustion stage nozzle provided in an embodiment of the present invention;

[0017] Figure 3 A schematic structural diagram of a fuel system of another auxiliary power unit provided by an embodiment of the present invention;

[0018] Figure 4 A schematic diagram of a control curve of a fuel system of an auxiliary power unit provided in an embodiment of the present invention;

[0019] Figure 5 A schematic flow chart of a method for controlling a fuel system of an auxiliary power unit provided by an embodiment of the present invention;

[0020] Figure 6 A schematic flow chart of another method for controlling a fuel system of an auxiliary power unit provided by an embodiment of the present invention;

[0021] Figure 7 A schematic structural diagram of an aircraft provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0023] In the prior art, the power unit of aircraft such as airplanes generally includes a main power unit and an auxiliary power unit. The flight altitude of airplanes tends to be higher and higher. When the main power unit of an airplane stops in the air at high altitude, the auxiliary power unit needs to be started to restart the main power unit, and it can provide power supply to the airplane when the main power unit stops in the air. Therefore, the high-altitude starting performance of the auxiliary power unit is extremely important. However, the inventors found in the process of realizing the present invention that when igniting and starting the auxiliary power unit, the higher the flight altitude, the smaller the amount of ignition fuel required, and the prior art is difficult to control to form a very small amount of ignition fuel, which easily causes the aircraft to fail to ignite at high altitude, limiting the flight altitude of the aircraft.

[0024] In order to solve the problem of height limitation of the auxiliary power unit in the air and improve the high-altitude starting performance of the auxiliary power unit, an embodiment of the present invention provides a fuel system for the auxiliary power unit, such as Figure 1 As shown, Figure 1 A schematic diagram of the structure of a fuel system of an auxiliary power unit provided in an embodiment of the present invention, the fuel system of the auxiliary power unit comprises: a controller 11, a fuel module 12, a first stop valve 14, a second stop valve 15, a third stop valve 16, a pre-combustion stage nozzle 17 and a main combustion stage nozzle 18;

[0025] The fuel module 12 is used to pressurize the fuel at the fuel inlet and transmit it to the first stop valve 14, the second stop valve 15 and the third stop valve 16 through the transmission pipeline 13; the controller 11 is electrically connected to the fuel module 12 and is used to control the rotation of the fuel pump of the fuel module 12;

[0026] The pre-combustion stage nozzle 17 includes a first nozzle channel 171 and a second nozzle channel 172; the first stop valve 14 transmits fuel to the first nozzle channel 171 through the first fuel main pipe 21; the second stop valve 15 transmits fuel to the second nozzle channel 172 through the second fuel main pipe 22; the third stop valve 16 transmits fuel to the main combustion stage nozzle 18 through the third fuel main pipe 23;

[0027] The controller 11 is electrically connected to the first stop valve 14 and the second stop valve 15 respectively, and is used to control the conduction of the first stop valve 14 and / or the second stop valve 15 so that the fuel supply amount transmitted by the fuel module 12 to the pre-combustion stage nozzle 17 is the ignition fuel amount of the auxiliary power unit; the controller 11 is also electrically connected to the third stop valve 16, and is used to control the conduction of the third stop valve 16 so that the third fuel main pipe 23 transmits fuel to the main combustion stage nozzle 18.

[0028] The auxiliary power unit can provide compressed air for the start of the main engine of the aircraft, provide compressed air for the aircraft environmental control system, provide ground power for the aircraft power system, and provide backup power after the main engine of the aircraft fails, etc., which provides a guarantee for the safe flight of the aircraft. In this embodiment, the fuel system of the auxiliary power unit is improved, so that when the auxiliary power unit is started at high altitude, the amount of ignition fuel can be controlled to be extremely small, ensuring the high-altitude start of the aircraft. Among them, the fuel system includes a controller 11, a fuel module 12, a first stop valve 14, a second stop valve 15, a third stop valve 16, a pre-combustion stage nozzle 17 and a main combustion stage nozzle 18. The controller 11 is electrically connected to the fuel module 12. Specifically, the fuel inlet refers to the inlet of the fuel system that provides fuel to the auxiliary power unit through a pipeline from the aircraft fuel tank or the ground fuel tank. The fuel module 12 is connected to this fuel inlet, so that the above-mentioned fuel can be obtained and the fuel can be pressurized so that the fuel has the pressure required by the subsequent equipment. The fuel module 12 can specifically adjust the pressure of the fuel by rotating the fuel pump. In addition to the fuel pump, the fuel module 12 may also include components such as a fuel fine filter, a bypass valve, a relief valve, and a fuel filter clogging signal sensor to assist in completing the fuel pressurization process. The controller 11 is electrically connected to the fuel module 12 and can control the rotation of the fuel pump. In addition, the controller 11 can also control the start-up, power regulation, bleed air generation, and fuel regulation of the auxiliary power unit.

[0029] The fuel module 12 pressurizes the fuel and pumps it into the transmission pipeline 13. The input end of the transmission pipeline 13 is connected to the output end of the fuel module 12, and the transmission pipeline 13 includes a first output end, a second output end, and a third output end. Among them, the input end, the first output end, the second output end, and the third output end of the transmission pipeline 13 are all connected to each other through pipelines. The first output end can be connected to the first stop valve 14, the second output end can be connected to the second stop valve 15, and the third output end can be connected to the third stop valve 16. The controller 11 is electrically connected to the first stop valve 14, the second stop valve 15, and the third stop valve 16, respectively, and is used to control the conduction or shutoff of the above three stop valves.

[0030] The fuel system includes a pre-combustion oil circuit and a main combustion oil circuit. The pre-combustion oil circuit mainly supplies fuel during the ignition stage of the auxiliary power unit, and the amount of fuel is small; the main combustion oil circuit mainly continues to supply fuel after the auxiliary power unit is ignited, and the amount of fuel is large. The transmission pipeline 13 can supply the fuel output by the fuel module 12 to the pre-combustion oil circuit and the main combustion oil circuit respectively.

[0031] The pre-combustion stage oil circuit includes a pre-combustion stage nozzle 17. The main function of the pre-combustion stage nozzle 17 is to spray the fuel supplied by the pre-combustion stage oil circuit into atomized form and injected into the combustion chamber during the ignition stage of the auxiliary power unit for ignition and combustion. The amount of fuel is small. The main combustion stage oil circuit includes a main combustion stage nozzle 18. The main combustion stage nozzle 18 is mainly used to continue to supply fuel after the auxiliary power unit is ignited, spray the fuel supplied by the main combustion stage oil circuit into atomized form and injected into the combustion chamber for ignition and combustion. The amount of fuel is large. Figure 2 A schematic diagram of the structure of a pre-combustion stage nozzle provided for an embodiment of the present invention. The pre-combustion stage nozzle is a dual-oil-circuit nozzle, and the dual-oil-circuit nozzle includes: a first nozzle channel 171 and a second nozzle channel 172. The first nozzle channel 171 and the second nozzle channel 172 are both connected to the combustion chamber. Optionally, the second nozzle channel 172 can be used as the main nozzle channel of the pre-combustion stage nozzle, and the first nozzle channel 171 can be used as the secondary nozzle channel of the pre-combustion stage nozzle. Exemplarily, the channel diameter of the main nozzle channel is larger than the channel diameter of the secondary nozzle channel, so that the fuel supply of the main nozzle channel is greater than the fuel supply of the secondary nozzle channel. In addition, the channel diameter of the main nozzle channel can also be equal to the channel diameter of the secondary nozzle channel. This embodiment does not specifically limit the size of the two nozzle channels.

[0032] The fuel main pipe includes a first fuel main pipe 21, a second fuel main pipe 22 and a third fuel main pipe 23. The first fuel main pipe 21 is used to connect the first stop valve 14 and the first nozzle channel 171; the second fuel main pipe 22 is used to connect the second stop valve 15 and the second nozzle channel 172; the third fuel main pipe 23 is used to connect the third stop valve 16 and the main combustion stage nozzle 18. The first fuel main pipe 21 and the first nozzle channel 171 constitute the first pre-combustion stage oil circuit; the second fuel main pipe 22 and the second nozzle channel 172 constitute the second pre-combustion stage oil circuit; the third fuel main pipe 23 and the main combustion stage nozzle 18 constitute the main combustion stage oil circuit. The first stop valve 14 is used to control the conduction of the first pre-combustion stage oil circuit under the control of the controller 11; the second stop valve 15 is used to control the conduction of the second pre-combustion stage oil circuit under the control of the controller 11; the third stop valve 16 is used to control the conduction of the main combustion stage oil circuit under the control of the controller 11.

[0033] During the ignition stage, the controller 11 controls the opening or closing of the first stop valve 14 and the second stop valve 15 to adjust the fuel supply amount transmitted from the first fuel main pipe 21 and the second fuel main pipe 22 to the pre-combustion stage nozzle 17 to the ignition fuel amount of the auxiliary power unit, thereby preventing the problem of excessive fuel supply to the pre-combustion stage nozzle 17. When the aircraft flies to a high altitude and the main power unit stops in mid-air, the dual oil circuit setting of the pre-combustion stage oil circuit can meet the extremely small ignition fuel amount demand of the auxiliary power unit. Exemplarily, when the ignition fuel amount demand of the auxiliary power unit is relatively small, one of the dual oil circuits can be opened. Specifically, only the first stop valve 14 can be turned on and the second stop valve 15 can be turned off, so that the pre-combustion stage oil circuit only provides fuel to the combustion chamber through the first nozzle channel 171, thereby realizing the supply of an extremely small amount of ignition fuel and ensuring the opening of the auxiliary power unit. If the ignition fuel quantity required is large and the fuel supply of the second nozzle channel 172 is greater than that of the first nozzle channel 171, the second stop valve 15 can be turned on, the first stop valve 14 can be turned off, and the pre-combustion stage oil circuit supplies fuel to the combustion chamber through the second nozzle channel 172. If the ignition fuel quantity required is even greater, the first stop valve 14 and the second stop valve 15 can be turned on at the same time, and the pre-combustion stage oil circuit supplies fuel to the combustion chamber through dual oil circuits. This embodiment achieves precise control of the ignition fuel quantity of the auxiliary power unit by controlling the dual oil circuits of the pre-combustion stage oil circuit, thereby ensuring successful ignition of the auxiliary power unit.

[0034] After the ignition phase is completed, the fuel system of the auxiliary power unit enters the working phase. The controller 11 controls the third shut-off valve 16 to conduct, so that the third fuel manifold 23 transmits fuel to the main combustion stage nozzle 18. The main combustion stage nozzle 18 provides more fuel for the combustion chamber.

[0035] In an embodiment of the present invention, in the fuel system of the auxiliary power unit, the fuel pump of the fuel module rotates under the control of the controller, and the fuel at the fuel inlet is pressurized and transmitted to the transmission pipeline. The output end of the transmission pipeline is connected to the first fuel main pipe through the first stop valve to transmit the fuel to the first nozzle channel of the pre-combustion stage nozzle; the output end of the transmission pipeline is connected to the second fuel main pipe through the second stop valve to transmit the fuel to the second nozzle channel of the pre-combustion stage nozzle; the output end of the transmission pipeline is connected to the third fuel main pipe through the third stop valve to transmit the fuel to the main combustion stage nozzle. The controller can control the conduction and shutoff of the first stop valve, the second stop valve and the third stop valve respectively. Specifically, by controlling the conduction of the first stop valve and / or the second stop valve, the fuel supply amount of the pre-combustion stage nozzle is the ignition fuel amount, and by controlling the conduction of the third stop valve, the fuel is transmitted to the main combustion stage nozzle. During the ignition stage of the fuel system, because the amount of ignition fuel for the auxiliary power unit at high altitude is extremely small, this embodiment controls the fuel supply to the pre-combustion stage nozzle by opening or closing the first stop valve and the second stop valve, so that the fuel supply is exactly the ignition fuel amount and does not exceed the amount, thereby ensuring the successful ignition of the auxiliary power unit at high altitude, being compatible with the large fuel demand of the auxiliary power unit, and expanding the use envelope of the auxiliary power unit.

[0036] The above is the core idea of ​​the present invention. The technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Figure 3 A structural schematic diagram of another fuel system of an auxiliary power unit provided in an embodiment of the present invention. Optionally, the fuel system of the auxiliary power unit may also include: a first one-way valve 191, a second one-way valve 192 and a third one-way valve 193; the first one-way valve 191 is arranged between the first stop valve 14 and the first fuel main pipe 21, and is used to control the fuel flow from the first stop valve 14 to the first nozzle channel 171; the second one-way valve 192 is arranged between the second stop valve 15 and the second fuel main pipe 22, and is used to control the fuel flow from the second stop valve 15 to the second nozzle channel 172; the third one-way valve 193 is arranged between the third stop valve 16 and the third fuel main pipe 23, and is used to control the fuel flow from the third stop valve 16 to the main combustion stage nozzle 18.

[0038] The three oil circuits of the fuel system of the auxiliary power unit are respectively provided with a one-way valve. The one-way valve can ensure that the fuel in the oil circuit flows from the fuel module 12 to the nozzle after the shut-off valve is opened. Specifically, the one-way valve may include a first one-way valve 191, a second one-way valve 192 and a third one-way valve 193. The first one-way valve 191 can control the fuel to flow to the first pre-combustion stage oil circuit after the first shut-off valve 14 is opened; the second one-way valve 192 can control the fuel to flow to the second pre-combustion stage oil circuit after the second shut-off valve 15 is opened; the third one-way valve 193 can control the fuel to flow to the main combustion stage oil circuit after the third shut-off valve 16 is opened. The one-way valve can effectively ensure the one-way flow of fuel in each oil circuit and prevent fuel backflow.

[0039] In addition, the first one-way valve 191, the second one-way valve 192 and the third one-way valve 193 can all play a damping role. For example, when the fuel system switches from opening the first pre-combustion level oil circuit to opening the first pre-combustion level oil circuit and the second pre-combustion level oil circuit at the same time, the flow rate of the fuel in the first pre-combustion level oil circuit may be sharply reduced. At this time, the fuel in the second pre-combustion level oil circuit has not yet reached the combustion chamber, and the pre-combustion level oil circuit provides very little fuel to the combustion chamber, which is prone to flameout, resulting in the failure of the fuel system to ignite successfully. However, the opening of the one-way valve requires a certain time delay. In this embodiment, when the second pre-combustion level oil circuit is opened, the flow rate of the fuel in the first pre-combustion level oil circuit will not be reduced too much at once, ensuring the fuel supply of the pre-combustion level oil circuit to the combustion chamber during the ignition stage, further improving the start-up success rate of the auxiliary power unit, and enhancing the reliability of the auxiliary power unit.

[0040] Optionally, the first nozzle channel 171 and the second nozzle channel 172 may both be connected to the combustion chamber; the pre-combustion stage nozzle 17 is used to spray the fuel transmitted by the first fuel main pipe 21 and / or the second fuel main pipe 22 into the combustion chamber in the ignition stage of the auxiliary power unit; the main combustion stage nozzle 18 may be connected to the combustion chamber, and is used to spray the fuel transmitted by the third fuel main pipe 23 into the combustion chamber in the working stage of the auxiliary power unit. It should be noted that when the pre-combustion stage nozzle 17 provides the ignition fuel amount for the ignition stage of the auxiliary power unit, whether the first nozzle channel 171 and the second nozzle channel 172 of the pre-combustion stage nozzle 17 in this embodiment supply fuel can be controlled separately. Exemplarily, the first stop valve 14 can be used to realize the separate supply of fuel to the first nozzle channel 171; the second stop valve 15 can be used to realize the separate supply of fuel to the second nozzle channel 172; or, the first stop valve 14 and the second stop valve 15 are simultaneously opened to realize the simultaneous supply of fuel to the first nozzle channel 171 and the second nozzle channel 172, so as to meet the situation where the ignition fuel amount of the auxiliary power unit is large under low temperature and low pressure.

[0041] Optionally, the controller 11 can also be used to obtain the current ignition fuel quantity of the auxiliary power unit based on the current ambient temperature and pressure; the controller 11 can also be used to control at least one of the first stop valve 14 and the second stop valve 15 to be conductive based on the current ignition fuel quantity, so that the fuel supply amount of the pre-combustion stage nozzle 17 is the ignition fuel quantity of the auxiliary power unit.

[0042] In actual application scenarios, the ignition fuel amount of the auxiliary power unit at high altitude and high pressure is small, and the ignition fuel amount of the auxiliary power unit at low altitude and low pressure is large. The inventor found from the above usage scenarios that environmental parameters such as the flight altitude, flight Mach number and current temperature of the aircraft can affect the current ignition fuel amount of the auxiliary power unit, and all the above environmental factors can be attributed to the two environmental parameters of temperature and pressure. Optionally, the controller 11 can also be used to obtain the current ignition fuel amount of the auxiliary power unit according to the temperature and pressure of the current environment. Specifically, the controller 11 can include sensing components such as temperature sensors and pressure sensors, and the sensing components can detect the temperature and pressure of the current environment, and the controller can also pre-store a fuel comparison table. As shown in Table 1, Table 1 is a comparison table of temperature, pressure and ignition fuel amount of the auxiliary power unit provided in an embodiment of the present invention. Different temperatures T or different pressures P can correspond to different ignition fuel amounts D. For example, when the temperature is T1 and the pressure is P1, the ignition fuel amount is D1; ​​when the temperature is T2 and the pressure is P2, the ignition fuel amount is D3. When the temperature is the same but the pressure is different, the corresponding ignition fuel quantity is also different. For example, when the temperature is T1, the ignition fuel quantity at the pressure of P1 is D1, and the ignition fuel quantity at the pressure of P2 is D2. According to the pre-stored fuel comparison table, the ignition fuel quantity required for the current environment can be obtained. It should be noted that the above comparison table can be obtained through experiments based on the characteristics of the auxiliary power system. Optionally, the data can be obtained before the auxiliary power system leaves the factory for user use.

[0043] Table 1: Comparison of temperature, pressure and ignition fuel quantity of auxiliary power unit

[0044] Temperature T(℃) Pressure P(pa) Ignition fuel quantity D(L) T1 P1 D1 T1 P2 D2 T2 P2 D3 … … …

[0045] The controller 11 can also be used to control at least one of the first stop valve 14 and the second stop valve 15 to be turned on according to the current ignition fuel quantity, so that the fuel supply quantity of the pre-combustion stage nozzle 17 is the current ignition fuel quantity of the auxiliary power unit. Exemplarily, when the current ignition fuel quantity is less than a certain set threshold, the first stop valve 14 can be controlled to be turned off, and the second stop valve 15 can be controlled to be turned on; when the current ignition fuel quantity is greater than a certain set threshold, the first stop valve 14 and the second stop valve 15 can be controlled to be turned on. The above-mentioned set threshold is set according to the critical fuel supply quantity of the dual oil circuit of the pre-combustion stage nozzle that can be atomized well.

[0046] In order to explain the control process of the fuel system of the auxiliary power unit in more detail, the present invention provides an introduction to the startup process of the auxiliary power unit:

[0047] First, the auxiliary power unit receives a start command. Optionally, the controller 11 may receive a start command, and the controller 11 may obtain the current ignition fuel quantity according to the comparison table. In addition, the controller is also used to obtain the fuel supply circuit combination of the fuel system according to the current ignition fuel quantity. Specifically, the controller of this embodiment may also be pre-installed with a fuel supply quantity-fuel pressure curve of the dual fuel circuit of the pre-combustion stage nozzle. Figure 4 As shown, Figure 4 A schematic diagram of a control curve of a fuel system of an auxiliary power unit provided in an embodiment of the present invention. Figure 4 It also includes the fuel supply-fuel pressure curve I+II of the dual oil circuit of the pre-combustion stage nozzle, that is, the dual oil circuit characteristic curve of the pre-combustion stage nozzle. It should be noted that Figure 4 The horizontal coordinate of the middle curve is pressure P, and the vertical coordinate is fuel quantity Q. In this embodiment, the first fuel pressure Pc can be selected from the curve I+II. The first fuel pressure Pc is the critical fuel pressure at which the pre-combustion stage nozzle can be completely atomized when the first nozzle channel 171 and the second nozzle channel 172 are connected at the same time. That is, when the fuel pressure is greater than the first fuel pressure Pc, the first nozzle channel 171 and the second nozzle channel 172 are connected at the same time to achieve complete atomization. When the fuel pressure is the first fuel pressure Pc, it can be known from the curve I+II that the ignition fuel quantity provided by the dual oil circuits of the pre-combustion stage nozzle is the first ignition fuel quantity Qc. In this embodiment, when the current ignition fuel amount is less than the first ignition fuel amount Qc, only the second nozzle channel 172 or the main nozzle channel can be opened; when the current ignition fuel amount is greater than the first ignition fuel amount Qc, the first nozzle channel 171 (secondary nozzle channel) and the second nozzle channel 172 (main nozzle channel) can be opened at the same time, so that the fuel supply amount of the pre-combustion stage nozzle is the ignition fuel amount of the auxiliary power unit. While accurately controlling the ignition fuel amount, the atomization effect of the fuel is guaranteed and the utilization rate of the fuel is improved. In summary, this embodiment can determine the fuel supply circuit combination mode by the ignition fuel amount.

[0048] Optionally, the controller 11 can also be used to obtain the specified speed of the fuel pump according to the current ignition fuel quantity and control the fuel pump to rotate at the specified speed. Specifically, the controller 11 determines the specified speed of the fuel pump according to the pre-installed fuel pump characteristic curve and the nozzle characteristic curve, as well as the current ignition fuel quantity. The controller 11 controls the fuel pump to rotate at the specified speed, thereby controlling the fuel supply amount provided by the fuel module to the subsequent equipment to be the ignition fuel quantity of the auxiliary power unit. Figure 4 As shown, Figure 4The fuel pump includes a fuel supply quantity-fuel pressure curve family, that is, a flow characteristic curve of the fuel pump; Figure 4 It also includes the fuel supply amount-fuel pressure curve I+II of the dual oil circuits of the pre-combustion stage nozzle, that is, the dual oil circuit characteristic curve in the pre-combustion stage nozzle characteristic curve; Figure 4 It also includes the fuel supply quantity-fuel pressure curve I of the single oil circuit of the pre-combustion stage nozzle, that is, the single oil circuit characteristic curve in the pre-combustion stage nozzle characteristic curve. Curve I+II is the characteristic curve when the dual oil circuits of the pre-combustion stage nozzle are fully open. Optionally, the single oil circuit can select the first pre-combustion stage oil circuit or the second pre-combustion stage oil circuit. In this embodiment, the second pre-combustion stage oil circuit is selected as the single oil circuit for schematic illustration. The fuel supply quantity-fuel pressure curve family of the fuel pump includes multiple fuel supply quantity-fuel pressure curves, and each fuel supply quantity-fuel pressure curve corresponds to a fixed speed n r The speed n of the fuel pump for different fuel supply-fuel pressure curves r Different. Figure 4 As shown, the fuel supply amount-fuel pressure curve family of the fuel pump includes a plurality of fuel supply amount-fuel pressure curves III with the same change trend. Optionally, along the direction in which the pressure P gradually decreases, the speed n corresponding to the fuel supply amount-fuel pressure curve III is r Gradually decrease. Figure 3 As shown, if the current ignition fuel quantity W f Greater than the first ignition fuel quantity Qc, for example, the current ignition fuel quantity W f The fuel quantity Q2 is obtained, and the nozzle characteristic curve is curve I+II. According to the curve I+II of the pre-combustion stage nozzle and the fuel supply quantity-fuel pressure curve family of the fuel pump, the fuel quantity Q in the curve is the current ignition fuel quantity W. f When the fuel supply amount-fuel pressure curve III intersects with the curve I+II (there is an intersection point A'), the speed n corresponding to the fuel supply amount-fuel pressure curve III is obtained. r , so the controller obtains the specified speed of the fuel pump according to curve III. If the current ignition fuel quantity W f is less than the first ignition fuel quantity Qc, for example, the current ignition fuel quantity W f is the fuel quantity Q1, Figure 4 The nozzle characteristic curve is curve I. According to the curve I of the pre-combustion stage nozzle and the fuel supply-fuel pressure curve family of the fuel pump, the fuel quantity Q in the curve is obtained as the current ignition fuel quantity W. f When the fuel supply amount-fuel pressure curve III intersects with the curve I (there is an intersection A), the speed n corresponding to the fuel supply amount-fuel pressure curve III is obtained. r , so that the controller obtains the specified speed of the fuel pump according to curve III.

[0049] The controller 11 is also used to control the starter motor of the auxiliary power unit to start, driving the engine rotor of the auxiliary power unit to rotate. When the engine rotor rotates to the set speed, the ignition exciter of the auxiliary power unit is powered on and ignites. The controller 11 controls the fuel module 12 to start working and controls the fuel pump to rotate at the specified speed. The controller 11 is also used to control the shut-off valve of the corresponding combined oil circuit to be turned on and the oil supply circuit to be opened. For example, if the dual oil circuits of the pre-combustion stage nozzle are turned on, the first shut-off valve and the second shut-off valve are controlled to be turned on; if the single oil circuit in the pre-combustion stage nozzle is turned on, the second shut-off valve is controlled to be turned on and the first shut-off valve is turned off.

[0050] After that, the fuel system enters the ignition stage, the fuel enters the pre-combustion stage nozzle, and is atomized and sprayed into the combustion chamber through the pre-combustion stage nozzle, and ignites under the action of the electric spark. After the ignition is successful, it enters the working stage, and the engine rotor speed of the auxiliary power unit continues to increase under the action of the starter motor and the turbine. The controller 11 controls the fuel pump speed to continue to increase, increase the fuel supply, and conducts the third stop valve to open the main combustion stage oil circuit. The engine rotor speed rises to the rated speed and the start is completed.

[0051] Based on the same concept, an embodiment of the present invention further provides a method for controlling a fuel system of an auxiliary power unit. Figure 5 A flow chart of a method for controlling a fuel system of an auxiliary power unit provided by an embodiment of the present invention is shown in FIG. Figure 5 As shown, the method of this embodiment includes the following steps:

[0052] Step S101: The controller obtains a start-up instruction of the auxiliary power unit, and controls the fuel pump of the fuel module to rotate according to the start-up instruction, so that the fuel module transmits fuel to the transmission pipeline.

[0053] Step S102: During the ignition phase of the auxiliary power unit, the controller controls the first shut-off valve and / or the second shut-off valve to be turned on, so that the fuel supply amount transmitted by the fuel module to the pre-combustion stage nozzle is the ignition fuel amount of the auxiliary power unit.

[0054] Step S103: During the working phase of the auxiliary power unit, the controller controls the third shut-off valve to be turned on so that the third fuel main pipe transmits fuel to the main combustion stage nozzle.

[0055] In an embodiment of the present invention, in the fuel system of the auxiliary power unit, the fuel pump of the fuel module rotates under the control of the controller, and the fuel at the fuel inlet is pressurized and transmitted to the transmission pipeline. The output end of the transmission pipeline is connected to the first fuel main pipe through the first stop valve to transmit the fuel to the first nozzle channel of the pre-combustion stage nozzle; the output end of the transmission pipeline is connected to the second fuel main pipe through the second stop valve to transmit the fuel to the second nozzle channel of the pre-combustion stage nozzle; the output end of the transmission pipeline is connected to the third fuel main pipe through the third stop valve to transmit the fuel to the main combustion stage nozzle. The controller can control the conduction and shutoff of the first stop valve, the second stop valve and the third stop valve respectively. Specifically, by controlling the conduction of the first stop valve and / or the second stop valve, the fuel supply amount of the pre-combustion stage nozzle is the ignition fuel amount, and by controlling the conduction of the third stop valve, the fuel is transmitted to the main combustion stage nozzle. During the ignition stage of the fuel system, because the amount of ignition fuel for the auxiliary power unit at high altitude is extremely small, this embodiment controls the fuel supply to the pre-combustion stage nozzle by opening or closing the first stop valve and the second stop valve, so that the fuel supply is exactly the ignition fuel amount and does not exceed the amount, thereby ensuring the successful ignition of the auxiliary power unit at high altitude, being compatible with the large fuel demand of the auxiliary power unit, and expanding the use envelope of the auxiliary power unit.

[0056] On the basis of the above embodiment, after the controller obtains the start-up instruction of the auxiliary power device, it can also include: the controller obtains the current ignition fuel oil amount of the auxiliary power device according to the temperature and pressure of the current environment; the controller controls the first stop valve and / or the second stop valve to be turned on, so that the fuel supply amount transmitted by the fuel module to the pre-combustion stage nozzle is the ignition fuel oil amount of the auxiliary power device, including: the controller controls at least one of the first stop valve and the second stop valve to be turned on according to the current ignition fuel oil amount, so that the fuel supply amount of the pre-combustion stage nozzle is the ignition fuel oil amount of the auxiliary power device. This embodiment obtains the ignition fuel oil amount currently required by the auxiliary power device according to the environmental parameters of the current environment. The ignition fuel oil amount is the fuel amount that the auxiliary power system can successfully start under the current environment. Exemplarily, in a high-temperature and high-altitude environment, the ignition fuel oil amount required by the auxiliary power device is small, and only one of the first stop valve and the second stop valve needs to be controlled to be turned on; in a low-temperature and low-altitude environment, the ignition fuel oil amount required by the auxiliary power device is large, and the first stop valve and the second stop valve can be controlled to be turned on at the same time. In this embodiment, the controller can realize different oil supply circuit combination modes through the pre-combustion stage nozzle of the dual oil circuit to meet the ignition fuel quantity requirements of the auxiliary power system under different environments, ensure the successful start-up of the auxiliary power unit at high altitude, and improve the reliability of the auxiliary power unit.

[0057] In a specific example, this embodiment passes Figure 4The flow characteristic curve of the fuel pump and the pre-combustion stage nozzle characteristic curve shown in the figure are used to describe the control process of the first stop valve and the second stop valve in detail. Specifically, Figure 6 As shown, Figure 6 A flow chart of another method for controlling a fuel system of an auxiliary power device provided by an embodiment of the present invention is shown in FIG. Figure 6 As shown, the method of this embodiment includes the following steps:

[0058] Step S201: The controller obtains a start instruction of an auxiliary power unit.

[0059] Step S202: The controller obtains the current ignition fuel quantity of the auxiliary power unit according to the current ambient temperature and pressure.

[0060] Step S203, the controller obtains the first ignition fuel amount of the pre-combustion stage nozzle corresponding to the first fuel pressure according to the fuel supply amount-fuel pressure curve of the dual oil circuits of the pre-combustion stage nozzle; the first fuel pressure is the critical fuel pressure at which the pre-combustion stage nozzle can be fully atomized when the first stop valve and the second stop valve are simultaneously turned on.

[0061] After obtaining the current ignition fuel quantity of the auxiliary power unit, the contents of step S203 may also be included. Figure 4 As shown, the controller can be pre-installed with the fuel supply-fuel pressure curve I+II of the dual oil circuits of the pre-combustion stage nozzle to obtain a critical fuel pressure, that is, the first ignition fuel quantity Qc. The first ignition fuel quantity Qc is determined according to the critical fuel pressure Pc, which is the critical fuel pressure at which the pre-combustion stage nozzle can be fully atomized when the dual oil circuits of the pre-combustion stage nozzle are opened at the same time. When the first ignition fuel quantity is greater than the first ignition fuel quantity Qc, the atomization effect can be good only through the two nozzle channels of the pre-combustion stage nozzle; when the first ignition fuel quantity is less than the first ignition fuel quantity Qc, one of the nozzles is used to reduce the fuel supply and realize the extremely small ignition fuel quantity requirement of the auxiliary power unit.

[0062] Step S204, if the current ignition fuel quantity is greater than the first ignition fuel quantity, the controller obtains the current fuel supply quantity-fuel pressure curve of the fuel pump corresponding to the current ignition fuel quantity based on the fuel supply quantity-fuel pressure curve family of the fuel pump and the fuel supply quantity-fuel pressure curve of the dual oil circuits of the pre-combustion stage nozzle; and obtains the specified speed of the fuel pump based on the current fuel supply quantity-fuel pressure curve.

[0063] Step S205, if the current ignition fuel amount is less than the first ignition fuel amount, the controller obtains the current fuel supply amount-fuel pressure curve of the fuel pump corresponding to the current ignition fuel amount based on the fuel supply amount-fuel pressure curve family of the fuel pump and the fuel supply amount-fuel pressure curve of the single oil circuit of the pre-combustion stage nozzle; and obtains the specified speed of the fuel pump based on the current fuel supply amount-fuel pressure curve.

[0064] After obtaining the first ignition fuel quantity of the auxiliary power unit, the contents of steps S204 and S205 may also be included. Figure 4 As shown, this embodiment can set the designated speed of the fuel pump according to the size relationship between the current ignition fuel amount and the first ignition fuel amount. Specifically, when the current ignition fuel amount is greater than the first ignition fuel amount, the current fuel supply amount-fuel pressure curve III of the fuel pump is obtained according to curve I+II, and the speed corresponding to curve III is obtained as the designated speed of the fuel pump; when the current ignition fuel amount is less than the first ignition fuel amount, the current fuel supply amount-fuel pressure curve III of the fuel pump is obtained according to curve I, and the speed corresponding to curve III is obtained as the designated speed of the fuel pump.

[0065] Step S206: The controller controls the fuel pump of the fuel module to rotate at a specified speed according to the start instruction.

[0066] “Controlling the rotation of the fuel pump of the fuel module according to the start instruction so that the fuel module transfers the fuel to the transmission pipeline” may specifically include the content of the above-mentioned step S206.

[0067] Step S207, if the current ignition fuel amount is less than the first ignition fuel amount, the controller controls the second stop valve to be turned on, so that the fuel supply amount transmitted from the second fuel main pipe to the pre-combustion stage nozzle is the ignition fuel amount of the auxiliary power unit; if the current ignition fuel amount is greater than the first ignition fuel amount, the controller controls the first stop valve and the second stop valve to be turned on, so that the fuel supply amount transmitted from the first fuel main pipe and the second fuel main pipe to the pre-combustion stage nozzle is the ignition fuel amount of the auxiliary power unit.

[0068] “During the ignition stage of the auxiliary power unit, the controller controls the first shut-off valve and / or the second shut-off valve to be turned on so that the fuel supply amount transmitted by the fuel module to the pre-combustion stage nozzle is the ignition fuel amount of the auxiliary power unit” may specifically include the content of step S207.

[0069] Step S208: During the working phase of the auxiliary power unit, the controller controls the third shut-off valve to be turned on so that the third fuel main pipe transmits fuel to the main combustion stage nozzle.

[0070] This embodiment determines the critical fuel quantity between the dual-oil circuit and the single-oil circuit switching, that is, the first ignition fuel quantity, through the pre-installed flow characteristic curve of the fuel pump and the characteristic curve of the pre-combustion stage nozzle, and determines the designated speed of the fuel pump according to the current ignition fuel quantity to supply fuel to the pre-combustion stage nozzle. At the same time, according to the relationship between the current ignition fuel quantity and the first ignition fuel quantity, the specific fuel supply circuit combination mode is determined, that is, it is determined whether the pre-combustion stage nozzle is supplied with fuel through the dual oil circuit or the single oil circuit, so as to further accurately control the current ignition fuel quantity, so as to ensure the successful start-up of the auxiliary power unit and meet its extremely small ignition fuel quantity demand.

[0071] An embodiment of the present invention further provides an electronic device. Figure 7 A schematic diagram of the structure of an aircraft provided by an embodiment of the present invention, such as Figure 7 As shown, the aircraft provided in the embodiment of the present invention includes: an auxiliary power unit 31; and a fuel system 32 of the auxiliary power unit provided in any embodiment of the present invention. The aircraft in this embodiment solves the problem of insufficient altitude range for the auxiliary power unit of an aircraft in the prior art to start in the air, improves the high-altitude starting performance of the auxiliary power unit 31, and ensures successful high-altitude ignition of the auxiliary power unit 31. Optionally, the aircraft in this embodiment can be a large aircraft, a medium-sized aircraft, a large helicopter, etc. This embodiment does not limit the specific type of aircraft and the way it is used. In addition, as Figure 7 As shown, the auxiliary power unit 31 and its fuel system 32 can be installed in the tail cone of the rear section of the fuselage, so that the auxiliary power unit can provide electricity and compressed air to the aircraft, while ensuring lighting and air conditioning in the cabin and cockpit.

[0072] The aircraft described in any embodiment of the present invention includes the technical features of the fuel system of the auxiliary power unit provided by any embodiment of the present invention, and has the beneficial effects of the corresponding technical features, which will not be repeated here.

[0073] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A fuel system for an auxiliary power unit, characterized in that: include: A controller, a fuel module, a first stop valve, a second stop valve, a third stop valve, a pre-combustion stage nozzle and a main combustion stage nozzle; The fuel module is used to pressurize the fuel in the fuel inlet and transmit it to the first stop valve, the second stop valve and the third stop valve through the transmission pipeline respectively; the controller is electrically connected to the fuel module and is used to control the rotation of the fuel pump of the fuel module; The pre-combustion stage nozzle comprises a first nozzle channel and a second nozzle channel; the first shut-off valve transmits fuel to the first nozzle channel through a first fuel main pipe; the second shut-off valve transmits fuel to the second nozzle channel through a second fuel main pipe; the third shut-off valve transmits fuel to the main combustion stage nozzle through a third fuel main pipe; The controller is electrically connected to the first stop valve and the second stop valve respectively, and is used to control the conduction of the first stop valve and / or the second stop valve so that the fuel supply amount transmitted by the fuel module to the pre-combustion stage nozzle is the ignition fuel amount of the auxiliary power unit; the controller is also electrically connected to the third stop valve, and is used to control the conduction of the third stop valve so that the third fuel main pipe transmits fuel to the main combustion stage nozzle.

2. The fuel system of the auxiliary power unit according to claim 1, characterized in that: Also includes: a first one-way valve, a second one-way valve and a third one-way valve; The first one-way valve is disposed between the first shut-off valve and the first fuel main pipe, and is used to control the fuel to flow from the first shut-off valve to the first nozzle channel; The second one-way valve is disposed between the second shut-off valve and the second fuel main pipe, and is used to control the fuel to flow from the second shut-off valve to the second nozzle channel; The third one-way valve is arranged between the third stop valve and the third fuel main pipe, and is used to control the fuel to flow from the third stop valve to the main combustion stage nozzle.

3. The fuel system of the auxiliary power unit according to claim 1, characterized in that: The first nozzle channel and the second nozzle channel are both connected to the combustion chamber; the pre-combustion stage nozzle is used to atomize and spray the fuel transmitted by the first fuel main pipe and / or the second fuel main pipe into the combustion chamber during the ignition stage of the auxiliary power unit; The main combustion stage nozzle is connected to the combustion chamber and is used to atomize and spray the fuel transmitted by the third fuel main pipe into the combustion chamber during the working stage of the auxiliary power unit.

4. The fuel system of the auxiliary power unit according to claim 1, characterized in that: The controller is also used to obtain the current ignition fuel oil quantity of the auxiliary power unit according to the temperature and pressure of the current environment; The controller is also used to control the conduction of at least one of the first shut-off valve and the second shut-off valve according to the current ignition fuel quantity, so that the fuel supply quantity of the pre-combustion stage nozzle is the ignition fuel quantity of the auxiliary power unit.

5. The fuel system of the auxiliary power unit according to claim 4, characterized in that: The controller is also used to obtain a specified rotation speed of the fuel pump according to the current ignition fuel quantity and control the fuel pump to rotate at the specified rotation speed.

6. A method for controlling a fuel system of an auxiliary power unit, characterized in that: A fuel system applicable to the auxiliary power unit according to any one of claims 1 to 5, comprising: The controller obtains a start-up instruction of the auxiliary power unit, and controls the rotation of the fuel pump of the fuel module according to the start-up instruction, so that the fuel module transmits fuel to the transmission pipeline; During the ignition phase of the auxiliary power unit, the controller controls the first shut-off valve and / or the second shut-off valve to be turned on, so that the fuel supply amount transmitted by the fuel module to the pre-combustion stage nozzle is the ignition fuel amount of the auxiliary power unit; During the operation phase of the auxiliary power unit, the controller controls the third shut-off valve to be turned on, so that the third fuel main pipe transmits fuel to the main combustion stage nozzle.

7. The control method of the fuel system of the auxiliary power unit according to claim 6, characterized in that: After the controller obtains the start-up instruction of the auxiliary power device, the controller further includes: The controller obtains the current ignition fuel quantity of the auxiliary power unit according to the temperature and pressure of the current environment; The controller controls the first shut-off valve and / or the second shut-off valve to be turned on so that the fuel supply amount transmitted by the fuel module to the pre-combustion stage nozzle is the ignition fuel amount of the auxiliary power unit, including: The controller controls at least one of the first shut-off valve and the second shut-off valve to be turned on according to the current ignition fuel quantity, so that the fuel supply quantity of the pre-combustion stage nozzle is the ignition fuel quantity of the auxiliary power unit.

8. The control method of the fuel system of the auxiliary power unit according to claim 7, characterized in that: After the controller obtains the current ignition fuel quantity of the auxiliary power unit according to the temperature and pressure of the current environment, it also includes: The controller obtains the first ignition fuel quantity of the pre-combustion stage nozzle corresponding to the first fuel pressure according to the fuel supply quantity-fuel pressure curve of the dual oil circuits of the pre-combustion stage nozzle; the first fuel pressure is the critical fuel pressure at which the pre-combustion stage nozzle can be completely atomized when the first shut-off valve and the second shut-off valve are simultaneously turned on; The controller controls at least one of the first shut-off valve and the second shut-off valve to be turned on according to the current ignition fuel quantity, so that the fuel supply quantity of the pre-combustion stage nozzle is the ignition fuel quantity of the auxiliary power unit, including: If the current ignition fuel quantity is less than the first ignition fuel quantity, the controller controls the second shut-off valve to be turned on, so that the fuel supply quantity transmitted by the second fuel main pipe to the pre-combustion stage nozzle is the ignition fuel quantity of the auxiliary power unit; If the current ignition fuel amount is greater than the first ignition fuel amount, the controller controls the first stop valve and the second stop valve to be turned on, so that the fuel supply amount transmitted by the first fuel main pipe and the second fuel main pipe to the pre-combustion stage nozzle is the ignition fuel amount of the auxiliary power unit.

9. The control method of the fuel system of the auxiliary power unit according to claim 8, characterized in that: After the controller obtains the first ignition fuel quantity of the pre-combustion stage nozzle corresponding to the first fuel pressure according to the fuel supply quantity-fuel pressure curve of the dual oil circuits of the pre-combustion stage nozzle, the controller further includes: If the current ignition fuel quantity is greater than the first ignition fuel quantity, the controller obtains the current fuel supply quantity-fuel pressure curve of the fuel pump corresponding to the current ignition fuel quantity according to the fuel supply quantity-fuel pressure curve family of the fuel pump and the fuel supply quantity-fuel pressure curve of the dual oil circuits of the pre-combustion stage nozzle; and obtains the specified speed of the fuel pump according to the current fuel supply quantity-fuel pressure curve; the fuel supply quantity-fuel pressure curve family of the fuel pump includes a plurality of fuel supply quantity-fuel pressure curves; the speeds of fuel pumps with different fuel supply quantity-fuel pressure curves are different; If the current ignition fuel quantity is less than the first ignition fuel quantity, the controller obtains the current fuel supply quantity-fuel pressure curve of the fuel pump corresponding to the current ignition fuel quantity according to the fuel supply quantity-fuel pressure curve family of the fuel pump and the fuel supply quantity-fuel pressure curve of the single oil circuit of the pre-combustion stage nozzle; and obtains the specified speed of the fuel pump according to the current fuel supply quantity-fuel pressure curve; Controlling the rotation of the fuel pump of the fuel module according to the start-up instruction includes: The controller controls the fuel pump of the fuel module to rotate at the specified speed according to the start instruction.

10. An aircraft, characterized in that: comprising: an auxiliary power unit; and a fuel system for the auxiliary power unit as described in any one of claims 1-5.

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