Aero-engine tcma fuel control system and method

Abstract

An aero-engine TCMA fuel control system comprises a return oil pressure regulating system arranged on a return oil branch, the return oil pressure regulating system forms a pressure regulating passage, the pressure regulating passage can depressurize or pressurize the return oil branch to adjust the fuel pressure upstream of a metering valve, the fuel supply to an engine combustion chamber is controlled by changing the pressure difference between the upstream and downstream of the metering valve, and the engine thrust is reduced to exit the TCMA state. The system does not need to change the main oil circuit, has simple structure and high reliability, can effectively realize the engine thrust reduction in the case of metering valve opening degree control failure, and improves the safety of the engine. The application also relates to a TCMA fuel control method.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of aero-engines, and particularly relates to an aero-engine TCMA fuel control system and method. BACKGROUND

[0002] An aero-engine fuel system mainly comprises a pump group, a constant pressure valve, an action component, a high pressure cut-off valve, a fuel grading method, a fuel nozzle, a metering valve, a differential pressure valve, a return valve, an overspeed valve, etc. After being pressurized by the pump group, the aircraft fuel is supplied to the engine combustion chamber by the fuel nozzle through the metering valve and the high pressure cut-off valve. The metering valve is used to measure the fuel quantity supplied to the engine combustion chamber, the high pressure cut-off valve is used to maintain sufficient minimum servo pressure of the system and cut off the fuel supply after the engine stops, the differential pressure valve is used to ensure that the pressure difference before and after the metering valve is constant to control the fuel supply quantity to the combustion chamber, and the return valve is used to send the fuel more than the demand of the engine back. Generally, in order to ensure the safety of the aero-engine operation, the aero-engine control system needs to have an overspeed protection function. When the aero-engine triggers an overspeed instruction, the fuel system can cut off the fuel supply to the combustion chamber, quickly complete the fuel cut-off action and make the engine stop. At present, due to the weight, structural complexity and other reasons, double electrical redundancy is used in the aero-engine control to ensure the safety and reliability of the control system, but the mechanical structure of the control system is usually single redundancy. In the state of take-off and other high thrust states, if the fuel metering valve is stuck in the large flow state, or the electrical and hydraulic servo valve and other electrical elements fail and the zero offset drift causes the fuel metering valve to be fully open, it will cause the engine to appear an uncontrolled high thrust event (UHT, uncontrolled high thrust), and trigger the thrust fault accommodation logic (TCMA, Thrust Control Malfunction Accommodation). In this state, the throttle lever thrust control is out of control, and the automatic stop will not be triggered until the overspeed state is reached, and only manual control by the pilot can be relied on, and the hysteresis of manual operation easily increases the risk of accidents. Therefore, it is of high value to provide an aero-engine TCMA fuel control system to improve the safety of the aero-engine. SUMMARY

[0003] The purpose of the present application is to provide an aero-engine TCMA fuel control system which can realize engine thrust reduction control in the metering valve stuck state. The present application also provides a TCMA fuel control method.

[0004] According to an embodiment of the present application, an aero-engine TCMA fuel control system is provided, which comprises a main oil path, a metering valve and a return oil branch. The metering valve is arranged on the main oil path, and the return oil branch is arranged downstream of the metering valve. The return oil branch can guide part of the fuel from the main oil path downstream of the metering valve back to the main oil path upstream of the metering valve to maintain the pressure difference between the upstream and downstream of the metering valve at a constant value. The aero-engine TCMA fuel control system further comprises a return oil pressure regulating system arranged on the return oil branch and forming a pressure regulating path to allow the return oil branch to be depressurized or pressurized through the pressure regulating path to change the pressure difference between the upstream and downstream of the metering valve.

[0005] Under normal conditions, the pressure difference between the upstream and downstream of the metering valve is maintained at a constant value by the pressure difference valve and the return oil valve on the return oil branch of the aero-engine. The output power of the engine is adjusted by adjusting the opening of the metering valve to control the fuel supply to the downstream combustion chamber. When the engine enters the TCMA state due to failure, the opening of the metering valve cannot be adjusted. The system can intervene through the return oil pressure regulating system to form a partial pressure on the return oil branch. Since the opening of the metering valve is fixed, the fuel supply is only related to the pressure difference between the upstream and downstream of the metering valve. By reducing the oil pressure of the return oil branch and thus the oil pressure upstream of the metering valve, the fuel supply is reduced to make the engine exit the TCMA state. The fuel supply can also be increased by increasing the pressure difference between the upstream and downstream of the metering valve to increase the fuel supply in the case of failure of the metering valve.

[0006] Further, in some embodiments, the return oil pressure regulating system comprises a single-stage jet check valve and a TCMA execution valve. The output pressure of the single-stage jet check valve is adjusted by electromagnetic control. The opening of the TCMA execution valve is controlled by the output pressure of the single-stage jet check valve. The TCMA execution valve controls the amount of fuel passing through the pressure regulating path. By arranging the return oil pressure regulating system on the return oil branch, direct changes to the structure of the main oil path of the engine are avoided, which helps to reduce the complexity of the fuel control system and facilitate the control of the weight of the engine.

[0007] Further, in some embodiments, the output pressure of the single-stage jet check valve is not lower than the low-pressure pressure of the aero-engine fuel system and not higher than the constant-pressure oil pressure of the aero-engine fuel system.

[0008] Further, in some embodiments, one end of the TCMA execution valve is connected to the single-stage jet check valve, and the other end of the TCMA execution valve is provided with a spring and connected to the low-pressure pipeline of the aero-engine fuel system. The opening of the TCMA execution valve is controlled by the pressure difference between the two ends of the TCMA execution valve.

[0009] Further, in some embodiments, the TCMA actuating valve comprises an oil return branch interface and two pressure regulating interfaces, the oil return branch interface is connected to the oil return branch, the two pressure regulating interfaces are connected to the low pressure line and the high pressure line of the aero-engine fuel system respectively, the TCMA actuating valve allows the oil return branch interface to be in a closed state or in a state of being connected to the low pressure line and / or the high pressure line of the aero-engine fuel system. When the aero-engine is in normal operation, the oil return branch interface is closed; when the metering valve fails and the engine thrust needs to be reduced, the oil return branch can be connected to the low pressure line to form a pressure relief to reduce the engine fuel supply; when the metering valve fails and the engine thrust needs to be increased, the oil return branch can be connected to the high pressure line to form a pressure increase to increase the engine fuel supply.

[0010] Further, in some embodiments, the opening of the TCMA actuating valve is continuously adjustable.

[0011] Further, in some embodiments, the oil return pressure regulating system further comprises a closed-loop control system, which can establish a mapping relationship between the pressure difference of the main oil line upstream and downstream of the metering valve and the value of the oil return branch pressure changed by the oil return pressure regulating system, so as to adjust the fuel supply of the main oil line downstream of the metering valve to a given target value.

[0012] According to another aspect of the embodiments of the present application, an aero-engine TCMA fuel control method is provided, which uses the aero-engine TCMA fuel control system provided in any of the above embodiments to control the aero-engine to exit the TCMA state.

[0013] Further, in some embodiments, the method of controlling the aero-engine to exit the TCMA state is to reduce the pressure of the main oil line upstream of the metering valve by the oil return pressure regulating system, thereby reducing the fuel supply to the combustion chamber.

[0014] Further, in some embodiments, the method of controlling the aero-engine to exit the TCMA state is to establish a mapping relationship between the pressure difference of the main oil line upstream and downstream of the metering valve and the amount of fuel discharged by the oil return pressure regulating system, and to adjust the fuel supply of the main oil line downstream of the metering valve to a given target value by adjusting the value of the pressure reduction or increase of the oil return branch by the oil return pressure regulating system. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a structural schematic diagram of an aero-engine fuel system in an embodiment;

[0016] Figure 2 is a structural schematic diagram of a TCMA fuel control system in an embodiment;

[0017] Figure 3Fig. 1 is a schematic diagram of an open-loop control system of a TCMA fuel control system in an embodiment of the present application;

[0018] Figure 4 Fig. 2 is a schematic diagram of a closed-loop control system of a TCMA fuel control system in an embodiment of the present application.

[0019] The meanings of the reference numerals are as follows: 100-main oil circuit; 101-low pressure pump; 102-high pressure pump; 103-constant pressure valve; 104-actuating part; 105-high pressure cut-off valve; 106-over speed valve; 107-fuel grading valve; 108a-fuel nozzle group I; 108b-fuel nozzle group II; 200-metering valve; 201-metering electro-hydraulic servo valve; 300-oil return branch; 301-pressure difference valve; 302-oil return valve; 400-oil return pressure regulating system; 401-single stage injection check valve; 402-valve body; 403-TCMA actuating valve; 404-first end cavity; 405-second end cavity; 406-spring; 407-oil return branch interface; 408-high pressure pressure regulating interface; 409-low pressure pressure regulating interface; Pb-low pressure of fuel system; Ps-high pressure of fuel system; Pc-constant pressure; P1-pressure before metering valve; P2-pressure after metering valve; P1'-pressure before metering valve after pressure relief; P2'-pressure after metering valve after pressure relief; P1"-pressure before metering valve under closed-loop control; P2"-pressure after metering valve under closed-loop control.

[0020] The above-mentioned drawings are intended to make a detailed description of the present application so that those skilled in the art can understand the technical concept of the present application, and are not intended to limit the present application. For the sake of brevity, the above-mentioned drawings only schematically draw the structures related to the technical features of the present application, and do not draw the complete structures and all the details in strict accordance with the actual proportions. DETAILED DESCRIPTION

[0021] The present application will be further described in detail through specific embodiments in combination with the drawings.

[0022] The phrase "embodiment" mentioned herein means that the specific features, structures or properties described in combination with the embodiments can be contained in at least one embodiment herein. The phrase appears at various positions in the specification does not necessarily refer to the same embodiment, nor is limited to mutually exclusive or alternative embodiments. Those skilled in the art should understand that the embodiments herein can be combined with other embodiments without structural conflicts.

[0023] In the description herein, unless otherwise explicitly specified and limited, the technical terms "mounting", "connection", "connection" and the like should be understood in a broad sense, which can be active connection, or fixed connection or integrated. For those skilled in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0024] In the description herein, the terms "upper", "lower", "left", "right", "lateral", "longitudinal", "height", "length", "width" and the like, which indicate the orientation or positional relationship, are intended to accurately describe the embodiments and simplify the description, and are not intended to limit the parts or structures involved to have a specific orientation, to be installed or operated in a specific orientation, and cannot be understood as a limitation on the embodiments herein.

[0025] In the description herein, the terms "first", "second" and the like are only used to distinguish different objects, and cannot be understood as indicating relative importance or limiting the number, specific order or primary and secondary relationship of the technical features described. In the description herein, the meaning of "a plurality of" is at least two.

[0026] The aero-engine under certain disclosure will trigger the thrust control malfunction accommodation (TCMA) adjustment logic, which poses a serious risk to the flight safety of the aircraft. In one embodiment, the structural diagram of the aero-engine fuel system is as follows Figure 1As shown, fuel is pressurized by low pressure pump 101 to form low pressure Pb, and further pressurized by high pressure pump 102 to form high pressure Ps. High pressure fuel is regulated by constant pressure valve 103 to form constant pressure Pc, which is used to drive various actuating components 104 of servo fuel circuit. Another part of high pressure fuel is sent to fuel staging valve 107 through high pressure cutoff valve 105 after passing through metering valve 200, and further sent to different fuel nozzles I 108a and fuel nozzle group II 108b. Super-turbo valve 106 is arranged downstream of metering valve 200 oil circuit, which is used to actuate after receiving super-turbo command. A branch including differential pressure valve 301 and return valve 302 is arranged downstream of metering valve 200, which can lead part of fuel downstream of metering valve 200 back to the oil circuit between low pressure pump 101 and high pressure pump 102. Differential pressure valve 301 senses the pressure difference between upstream and downstream of metering valve 200, and then controls the opening of return valve 302 to maintain the pressure difference between upstream and downstream of metering valve 200 constant, which makes the fuel flow of metering valve 200 only related to the opening of metering valve 200 itself. Adjusting the opening of metering valve 200 under normal working conditions can adjust the amount of fuel supplied to the combustion chamber, and further adjust the engine thrust. Due to the consideration of structural design and weight reduction, an aero-engine usually only has one set of mechanical structure for the above fuel system, and adopts double electrical redundancy in control logic to ensure safety and reliability. This leads to the fact that in the state of large thrust such as take-off, if the opening adjustment function of metering valve 200 fails due to mechanical failure, metering valve 200 is fully open, which will cause the engine to have an uncontrolled high thrust event (UHT), and trigger the thrust control malfunction accommodation (TCMA) adjustment logic. In this state, the throttle lever thrust control fails, the undervoltage state does not trigger automatic shutdown, and the only way to solve the problem is to manually shut down the engine by the pilot. In the state of large thrust, manual control is prone to cause the risk of aircraft thrust imbalance, loss of control, aircraft stall and other accidents.

[0027] To solve the above problems, an embodiment of one aspect of the present application provides an aero-engine TCMA control system, which has the structure as shown in Figure 2 , and the control logic as shown in Figure 1The structural schematic diagram of the shown aero-engine fuel system is different in that a set of oil return pressure regulating system 400 is arranged on the oil return branch 300 communicated to the main oil line 100 upstream of the metering valve 200 downstream of the metering valve 200, the oil return pressure regulating system 400 has a pressure regulating passage and can discharge part of the fuel to depressurize the oil return branch 300. The metering valve front pressure P1 is formed by the fuel introduced by the oil return branch 300, and the difference between P1 and P2 can be reduced by depressurizing the oil return branch 300 to reduce P1 and further reduce the difference between P1 and P2. When the control of the metering valve 200 fails, the opening degree cannot be adjusted, and according to the thin-walled orifice cut-off formula (wherein, W f is the metering flow, μ is the flow coefficient, A is the window area of the metering valve 200, ΔP=P1-P2, and ρ is the fuel density), reducing ΔP can reduce the fuel metering flow, thereby reducing the fuel supply to the combustion chamber, and further achieving the purpose of reducing the engine thrust to exit the TCMA state. For example, reducing ΔP to 1 / 9 before the oil return pressure regulating system 400 is involved can reduce W f to 1 / 3, effectively reducing the engine thrust.

[0028] In the preferred embodiment, the oil return pressure regulating system 400 includes a single-stage jet check valve 401 and a TCMA execution valve 403, the single-stage jet check valve 401 includes an electromagnetic control valve body 402, and the output pressure of the single-stage jet check valve 401 can be adjusted between Pb and Pc by controlling the actuation of the valve body 402, and the opening degree of the TCMA execution valve 403 can be changed by adjusting the output pressure to control the pressure relief.

[0029] In the preferred embodiment, the first end cavity 404 of the TCMA execution valve 403 is connected to the single-stage jet check valve 401; the second end cavity 405 is provided with a spring 406 and is connected to an oil line with Pb, and the resultant force of Pb and the spring force of the spring 406 is constant. By controlling the pressure output by the single-stage jet check valve 401 to the first end cavity 404, the pressure balance state of the first end cavity 404 and the second end cavity 405 can be changed to control the opening degree of the TCMA execution valve 403.

[0030] In a preferred embodiment, the TCMA actuating valve 403 has an oil return branch interface 407, which is connected to the oil return branch 300; the TCMA actuating valve 403 also has a high pressure regulating interface 408 connected to a pipe with Ps and a low pressure regulating interface 409 connected to a pipe with Pb. When the TCMA actuating valve 403 is at different opening degrees, the oil return branch interface 407 has different connection states: when the oil return branch interface 407 is in a closed state, the oil return branch 300 does not depressurize; when the oil return branch interface 407 is connected to the low pressure regulating interface 409, the oil return branch 300 depressurizes; when the oil return branch interface 407 is connected to the high pressure regulating interface 408, the oil return branch 300 pressurizes. In a further preferred embodiment, by adjusting the opening degree of the TCMA actuating valve 403, continuous adjustment of the oil return branch depressurization can be achieved: when the TCMA actuating valve 403 is fully connected to the low pressure regulating interface 409, a pressure difference of P2-Pb is formed to depressurize the fuel through the low pressure regulating interface 409; when the TCMA actuating valve 403 is fully connected to the high pressure regulating interface 408, a pressure difference of Ps-P2 is formed to pressurize the fuel through the high pressure regulating interface 408; the TCMA actuating valve 403 can be continuously adjusted between the two states.

[0031] In a preferred embodiment, the oil return pressure regulating system 400 has a closed loop control system, which adjusts the actuation of the valve body 402 by controlling the control current of the single stage injection check valve 401, thereby achieving continuous adjustment of the input pressure of the single stage injection check valve 401, establishing a mapping relationship between the output pressure of the single stage injection check valve 401 and the actuation stroke of the TCMA actuating valve 403, and allowing the oil return branch interface 407 to be partially connected to the high pressure regulating interface 408 and partially connected to the low pressure regulating interface 409. By controlling the control current of the single stage injection check valve 401, continuous control of the oil return pressure regulating system 400 is achieved, and in the case of failure of the metering valve 200 control, closed loop control of the engine thrust is still possible.

[0032] In a preferred embodiment, the process of controlling the aero-engine by the aero-engine TCMA fuel control system as shown in Figure 2

[0033] ​Under normal operating conditions, the single-stage spray block valve 401 controls the TCMA actuator valve 403 to keep the oil return branch interface 407 in a shut-off state. Part of the fuel downstream of the metering valve 200 is transported back to the main oil circuit 100 through the oil return branch 300, and under the regulation of the differential pressure valve 301 and the oil return valve 302, the difference between the pressure P1 before the metering valve and the pressure P2 after the metering valve upstream and downstream of the metering valve 200 is maintained at a fixed value. The metering electro-hydraulic servo valve 201 outputs pressure within the range from Pb to Pc to control the opening of the metering valve 200. Since the difference between P1 and P2 is a fixed value, the fuel quantity passing through the metering valve 200 is only affected by the opening of the metering valve 200. Under normal operating conditions, Ps > Pc > Pb, and Ps > P1 > P2.

[0034] Under abnormal operating conditions, when the metering valve 200 is stuck or the metering electro-hydraulic servo valve 201 fails, the metering valve 200 maintains the maximum opening and cannot be adjusted, and the engine enters the TCMA state. At this time, in some embodiments, by adjusting the current of the single-stage spray block valve 401, the valve body 402 of the single-stage spray block valve 401 is actuated to the state as shown in Figure 3 At this time, the single-stage spray block valve 401 outputs pressure Pc to the TCMA actuator valve 403, compressing one side of the second end chamber 405, and the oil return branch interface 407 is connected to the low-pressure pressure regulating interface 409. At this time, the fuel pressure output from the oil return branch 300 to the oil return branch interface 407 is P2, and P2 > Pb. Part of the fuel is discharged through the low-pressure pressure regulating interface 409 to achieve pressure relief. In this way, the fuel pressure output from the oil return branch 300 to the main oil circuit 100 decreases. Under the action of the differential pressure valve 301 and the oil return valve 302, the pressure P1' before the metering valve after pressure relief is formed, and P1' < P1. Under transient conditions, P1' - P2 < P1 - P2, and the fuel quantity passing through the metering valve 200 decreases, and the engine thrust decreases; as the pressure of the main oil circuit decreases, the pressure P2' after the metering valve after pressure relief is gradually formed, and P2' < P2. At the same time, since the oil return pressure regulating system maintains pressure relief, P1' - P2' < P1 - P2 still holds under steady-state conditions, thereby reducing the engine thrust and exiting the TCMA state.

[0035] In the preferred embodiment, in the case of the metering valve 200 being stuck or the metering electro-hydraulic servo valve 201 being failed, the engine enters the TCMA state with the metering valve 200 continuously at the maximum opening and unable to be adjusted. At this time, the mapping relationship between the input current of the single-stage spool valve 401 and the TCMA actuator opening is established through the closed-loop control system, and the proportional pressure distribution of the oil return branch 300 to the high-pressure regulating interface 408 and the low-pressure regulating interface 409 is realized by adjusting the input current of the single-stage spool valve 401, so that the pressure changed by the oil return regulating system 400 to the oil return branch 300 can be continuously changed, thereby realizing the continuous adjustment of the difference between the pre-pressure P1” of the metering valve under closed-loop control and the post-pressure P2” of the metering valve under closed-loop control. Further mapping the input power of the single-stage spool valve 401 to the engine speed or thrust can realize the closed-loop control of the engine speed or thrust in the case of the metering valve 200 opening adjustment failure, and adjust the engine to the specified working state.

[0036] The above-mentioned embodiments of the aircraft engine TCMA fuel control system can reduce the engine thrust by depressurizing the oil return branch to exit the TCMA state, thereby improving the reliability and safety of engine control. At the same time, the system has a simple structure and does not need to change the main oil circuit of the original engine fuel control system, has low complexity, and does not cause significant weight increase.

[0037] The purpose of the above-mentioned embodiments is to further illustrate the present application in combination with the drawings, so that those skilled in the art can understand the technical concept of the present application. Within the scope of the present application, optimization or equivalent replacement of the structures or methods involved, and combination of the embodiments in different embodiments without structural and principle conflicts, all fall within the protection scope of the present application.

Claims

1. An aero-engine TCMA fuel control system comprising a main fuel path, a metering valve and a fuel return branch, the metering valve being arranged on the main fuel path, a fuel return branch being arranged downstream of the metering valve, the fuel return branch being capable of diverting a portion of fuel from the main fuel path downstream of the metering valve back into the main fuel path upstream of the metering valve to maintain a constant pressure differential across the metering valve, characterised in that, The aero-engine TCMA fuel control system further comprises a fuel return pressure regulating system, which is arranged on the fuel return branch and forms a pressure regulating passage to allow the fuel return branch to be depressurized or pressurized through the pressure regulating passage to change the pressure difference between the upstream and downstream of the metering valve; The fuel return pressure regulating system comprises a single-stage jet check valve and a TCMA actuating valve, the single-stage jet check valve adjusts the output pressure through electromagnetic control, the opening degree of the TCMA actuating valve is controlled by the output pressure of the single-stage jet check valve, and the TCMA actuating valve controls the fuel quantity passing through the pressure regulating passage; The pressure output by the single-stage jet check valve is not lower than the low pressure of the aero-engine fuel system and is not higher than the constant pressure of the aero-engine fuel system; One end of the TCMA actuating valve is connected with the single-stage jet check valve, the other end is provided with a spring and is connected with the low pressure pipeline of the aero-engine fuel system, and the opening degree of the TCMA actuating valve is controlled by the pressure difference between the two ends of the TCMA actuating valve; The TCMA actuating valve comprises a fuel return branch interface and two pressure regulating interfaces, the fuel return branch interface is connected with the fuel return branch, the two pressure regulating interfaces are connected with the low pressure pipeline and the high pressure pipeline of the aero-engine fuel system respectively, and the TCMA actuating valve allows the fuel return branch interface to be in a closed state or to be connected with the low pressure pipeline and / or the high pressure pipeline of the aero-engine fuel system; The opening degree of the TCMA actuating valve is continuously adjustable.

2. The aircraft engine TCMA fuel control system in accordance with claim 1, wherein, The fuel return pressure regulating system further comprises a closed-loop control system, which can establish a mapping relationship between the pressure difference of the main oil passage between the upstream and downstream of the metering valve and the pressure value of the fuel return branch changed by the fuel return pressure regulating system to adjust the fuel supply quantity of the main oil passage downstream of the metering valve to a given target value.

3. A method of TCMA fuel control for an aeroengine, characterised in that, The aero-engine TCMA fuel control system according to any one of claims 1 to 2 is used to control the aero-engine to exit the TCMA state.

4. The aircraft engine TCMA fuel control method of claim 3, wherein, The method for controlling the aero-engine to exit the TCMA state is to reduce the fuel supply quantity of the combustion chamber by reducing the pressure of the main oil passage upstream of the metering valve through the fuel return pressure regulating system.

5. The aircraft engine TCMA fuel control method of claim 3, wherein, The method for controlling the aero-engine to exit the TCMA state is to establish a mapping relationship between the pressure difference of the main oil passage between the upstream and downstream of the metering valve and the fuel discharge quantity of the fuel return pressure regulating system, and to adjust the fuel supply quantity of the main oil passage downstream of the metering valve to a given target value by adjusting the pressure reduction or pressure increase value of the fuel return branch of the fuel return pressure regulating system.

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