A method and system for controlling an aircraft brake system

Abstract

The present application relates to the technical field of aircraft brake, in particular to a kind of control method and system of aircraft brake system, the method includes: obtaining the first brake instruction signal, second brake instruction signal corresponding to each foot pedal;Output the foot pedal instruction signal of each foot pedal;Control cut-off valve to open, servo valve outputs hydraulic pressure;Output brake pressure, and control the hydraulic system of main wheel to carry out main wheel brake.The present application can maintain 50% brake capacity under single fault when brake system fails, and carry out emergency braking under double fault, thereby significantly improve the safety of brake system.

Description

Technical Field

[0001] This invention relates to the field of aircraft braking technology, and more specifically to a control method and system for an aircraft braking system. Background Technology

[0002] The aircraft wheel braking system is a critical component ensuring safe landing and taxiing. During braking, the system's structure is relatively simple, and when key components (such as the hydraulic power source and control valves) fail, there is a lack of effective backup and switching mechanisms, posing a safety hazard. A single control method may result in complete loss of braking capability in the event of a failure, also presenting a safety risk.

[0003] Current aircraft braking systems use fly-by-wire braking for control, powered by a single hydraulic source. When this hydraulic source is lost, braking capability is lost. Some braking systems use a single shut-off valve; when this valve malfunctions, braking capability is lost.

[0004] Therefore, there is a need to provide a control method and system for an aircraft braking system to solve the above problems. Summary of the Invention

[0005] To address the problem that current braking systems lack backup systems and suffer from loss of braking function due to single-point failures, this invention provides a control method and system for an aircraft braking system to solve the existing problems.

[0006] The first aspect of the present invention provides a control system for an aircraft braking system, the system employing the following technical solution, including:

[0007] The pedal displacement detection module is used to detect the brake command signals corresponding to the driver's left pedal, driver's right pedal, passenger's left pedal, and passenger's right pedal.

[0008] The brake control valve module is used to control the flow of hydraulic oil in the hydraulic systems of the main landing gear on both sides of the aircraft and to output hydraulic pressure.

[0009] The manual brake drive module is used to open the emergency stop brake valve.

[0010] The pressure supply module is used to supply hydraulic oil to the brake control valve module and the emergency brake valve for shutdown.

[0011] The brake control module is used to control the opening and closing of the brake control valve module and output hydraulic pressure based on the brake command signals from the driver's left foot pedal, the driver's right foot pedal, the passenger's left foot pedal, and the passenger's right foot pedal.

[0012] An automatic brake selection switch is used to input the position signal of the automatic brake selection switch to the brake control module, wherein the brake control module is used to provide a locking voltage to the automatic brake selection switch;

[0013] It also includes a pressure conversion module, which outputs braking pressure based on the preset conversion pressure, the hydraulic pressure output by the brake control valve and the emergency stop brake valve, and provides the braking pressure to the hydraulic system of the main engine wheel to brake the main engine wheel.

[0014] A further technical solution of the present invention includes a foot pedal displacement detection module comprising:

[0015] The first pedal sensor unit is used to detect the brake command signal from the driver's left pedal;

[0016] The second pedal sensor unit is used to detect the brake command signal from the driver's right pedal;

[0017] The third pedal sensor unit is used to detect the brake command signal from the passenger's left pedal;

[0018] And a fourth pedal sensor unit, used to detect the brake command signal of the passenger's right pedal;

[0019] The braking command signal includes a first braking command signal and a second braking command signal. The first pedal sensor unit, the second pedal sensor unit, the third pedal sensor unit, and the fourth pedal sensor unit all include a first displacement sensor and a second displacement sensor. The first displacement sensor is used to detect the first braking command signal corresponding to the pedal, and the second displacement sensor is used to detect the second braking command signal corresponding to the pedal.

[0020] A further technical solution of the present invention includes a brake control module comprising:

[0021] The first brake controller is used to receive the first brake command signal detected by the first displacement sensor corresponding to the first pedal sensor unit, the second pedal sensor unit, the third pedal sensor unit, and the fourth pedal sensor unit.

[0022] The second brake controller is used to receive the second brake command signal detected by the second displacement sensor corresponding to the first pedal sensor unit, the second pedal sensor unit, the third pedal sensor unit, and the fourth pedal sensor unit.

[0023] The first brake controller and the second brake controller are connected in communication.

[0024] A further technical solution of the present invention is that the brake control valve module includes: a first brake control valve unit and a second brake control valve unit. The first brake control valve unit and the second brake control valve unit have the same structure, both including a shut-off valve and a servo valve.

[0025] The shut-off valve of the first brake control valve unit is used to control the on / off of hydraulic oil in the hydraulic system of the left main engine wheel, and the servo valve of the first brake control valve unit is used to output hydraulic pressure.

[0026] The shut-off valve of the second brake control valve unit is used to control the on / off of hydraulic oil in the hydraulic system of the right main engine wheel, and the servo valve of the second brake control valve unit is used to output hydraulic pressure.

[0027] Specifically, when the brake control module receives a first brake command signal or a second brake command signal, the brake control module controls the corresponding shut-off valves of the first brake control valve unit and the second brake control valve unit to open, and controls the corresponding servo valves of the first brake control valve unit and the second brake control valve unit to output the corresponding hydraulic pressure.

[0028] A further technical solution of the present invention includes a pressure supply module comprising: a first pressure supply unit and a second pressure supply unit;

[0029] Both the first pressure supply unit and the second pressure supply unit include: a hydraulic source, a check valve, and an accumulator connected in sequence. The hydraulic source supplies hydraulic oil to the accumulator through the check valve. The output end of the accumulator of the first pressure supply unit is connected to the first brake control valve unit and the emergency stop brake valve, respectively. The output end of the accumulator of the second pressure supply unit is connected to the second brake control valve unit and the emergency stop brake valve, respectively.

[0030] The first brake controller is used to control the accumulator of the first pressure supply unit to provide hydraulic oil to the first brake control valve unit and the emergency stop brake valve when the pressure signal of the hydraulic source of the first pressure supply unit is less than or equal to the brake pressure threshold; and to control the hydraulic source of the first pressure supply unit to provide hydraulic oil to the first brake control valve unit and the emergency stop brake valve when the pressure signal of the hydraulic source of the first pressure supply unit is greater than the brake pressure threshold. The second brake controller is used to control the accumulator of the second pressure supply unit to provide hydraulic oil to the second brake control valve unit and the emergency stop brake valve when the pressure signal of the hydraulic source of the second pressure supply unit is less than or equal to the brake pressure threshold; and to control the hydraulic source of the second pressure supply unit to provide hydraulic oil to the second brake control valve unit and the emergency stop brake valve when the pressure signal of the hydraulic source of the second pressure supply unit is greater than the brake pressure threshold.

[0031] A further technical solution of the present invention includes a pressure conversion module comprising: multiple pressure conversion valves, the outlet of each pressure conversion valve being connected to the hydraulic oil inlet of a hydraulic system of a main engine wheel, and the inlet of each pressure conversion valve being connected to the outlet of a brake control valve module and a shutdown emergency brake valve, respectively.

[0032] A further technical solution of the present invention includes a manual brake drive module comprising: a brake handle, which is connected to a stop emergency brake valve via a steel cable, wherein the stop emergency brake valve is used to output hydraulic pressure according to the displacement of the steel cable.

[0033] A second aspect of the present invention provides a control method for an aircraft braking system, the system employing the following technical solution, including:

[0034] Based on the landing gear signal input from the automatic braking switch, the automatic braking selector switch is locked in the landing gear until the aircraft is on the ground, at which point the aircraft is controlled to enter automatic braking.

[0035] The first brake command signal and the second brake command signal corresponding to the driver's left foot pedal, driver's right foot pedal, passenger's left foot pedal and passenger's right foot pedal are respectively acquired;

[0036] The maximum value of the first command signals corresponding to the driver's left pedal and the passenger's left pedal is taken as the first pedal command signal; the maximum value of the first command signals corresponding to the driver's right pedal and the passenger's right pedal is taken as the second pedal command signal; the maximum value of the second command signals corresponding to the driver's left pedal and the passenger's left pedal is taken as the third pedal command signal; the maximum value of the second command signals corresponding to the driver's right pedal and the passenger's right pedal is taken as the fourth pedal command signal.

[0037] The first brake controller and the second brake controller determine the state of each pedal according to the corresponding pedal command signal and the pedal depressing threshold value. The first brake controller and the second brake controller share the pedal state and output the corresponding pedal command signal value. Based on the pedal command signal value, they control the opening and closing of the shut-off valve of the corresponding brake control valve unit to release the automatic brake; and control the hydraulic pressure output by the servo valves corresponding to the first brake control valve unit and the second brake control valve unit.

[0038] Detect the fault status of the braking system. Fault status includes: the braking system has not lost its braking ability, has lost less than half of its braking ability, has lost half of its braking ability, and has lost more than half of its braking ability. When the braking system loses half or more of its braking ability, use the brake lever for emergency braking.

[0039] Based on the hydraulic pressure output by the servo valve, the hydraulic pressure output by the emergency brake valve, and the preset conversion pressure, the brake pressure is output, and the hydraulic system of the main wheel is controlled to brake the main wheel according to the brake pressure.

[0040] A further technical solution of the present invention includes the following steps: the first brake controller and the second brake controller determine the state of each pedal based on the corresponding pedal command signal and the pedal depressing threshold value; the first brake controller and the second brake controller share the pedal state and output the corresponding pedal command signal value; the first brake controller and the second brake controller control the on / off of the shut-off valve of the corresponding brake control valve unit according to the pedal command signal value to control the automatic brake release; and the steps of controlling the hydraulic pressure output by the servo valves corresponding to the first brake control valve unit and the second brake control valve unit include:

[0041] The first brake controller determines the driver's pedal status based on the first pedal command signal, the second pedal command signal, and the corresponding pedal depressing threshold value. The second brake controller determines the passenger's pedal status based on the third pedal command signal, the fourth pedal command signal, and the corresponding pedal depressing threshold value. The pedal status includes being depressed and not depressed.

[0042] The first brake controller and the second brake controller share information on the pedal status of the driver and the pedal status of the passenger. The first brake controller outputs the pedal command signal value of the driver's pedal based on the pedal status of the passenger, and the second brake controller outputs the pedal command signal value of the passenger based on the pedal status of the driver.

[0043] When at least one pedal is depressed, the first brake controller releases the automatic brake.

[0044] Based on the signal value of the pedal command signal from the driver's pedal, the on / off state of the shut-off valve of the first brake control valve unit is controlled; based on the signal value of the pedal command signal from the passenger's pedal, the on / off state of the shut-off valve of the second brake control valve unit is controlled, and the hydraulic pressure output by the servo valves corresponding to the first and second brake control valve units is controlled.

[0045] A further technical solution of the present invention, wherein the step of outputting braking pressure based on the hydraulic pressure output by the servo valve, the hydraulic pressure output by the emergency brake valve, and the preset conversion pressure is as follows:

[0046] If the difference between the hydraulic pressure output by the servo valve and the hydraulic pressure output by the emergency brake valve is greater than or equal to the preset conversion pressure, then the hydraulic pressure of the servo valve will be used as the brake pressure.

[0047] If the difference between the hydraulic pressure output by the emergency stop valve and the hydraulic pressure output by the servo valve is greater than or equal to the preset conversion pressure, then the hydraulic pressure output by the emergency stop valve will be used as the braking pressure.

[0048] If the absolute value of the difference between the hydraulic pressure output by the servo valve and the hydraulic pressure output by the emergency brake valve is less than the switching pressure, then the brake pressure output at the previous moment will be used as the current brake pressure.

[0049] The beneficial effects of this invention are:

[0050] 1. By integrating signals from multiple displacement sensors in the foot pedal displacement detection module and employing a redundant design in the dual brake controller, millisecond-level response to braking commands is achieved. The pressure supply unit is designed as a hydraulic source, a check valve, and an accumulator, enabling automatic switching between the hydraulic source and accumulator to supply hydraulic oil to the brake control valve unit. The brake control module is designed as a first brake controller and a second brake controller, allowing for cross-validation between them. A manual brake drive module provides mechanical emergency backup, forming a triple redundancy mechanism. This ensures the system maintains 50% braking capacity even under a single fault and retains emergency braking functionality under dual faults, significantly improving safety.

[0051] 3. By designing an automatic brake selection switch and a manual brake drive module, the system can seamlessly switch between automatic braking mode and manual emergency mode. At the same time, the mechanical emergency channel does not require power support, meeting the braking needs under extreme failure scenarios. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a system block diagram of a control system for an aircraft braking system according to the present invention;

[0054] Figure 2 This is a schematic diagram showing the connection of the foot pedal displacement detection module and the brake control module in an embodiment of the present invention.

[0055] Figure 3 This is a schematic diagram of the brake control valve unit in an embodiment of the present invention;

[0056] Figure 4 This is a flowchart of the control method for the aircraft braking system in an embodiment of the present invention;

[0057] Figure 5 This is a detailed flowchart of the control method for the aircraft braking system in an embodiment of the present invention;

[0058] Figure 6 This is a schematic diagram of the displacement and hydraulic pressure curves of the steel cable.

[0059] In the diagram: 1. Automatic brake selector switch; 2. First pedal sensor unit; 3. Second pedal sensor unit; 4. Third pedal sensor unit; 5. Fourth pedal sensor unit; 6. First hydraulic source; 7. Second hydraulic source; 8. Brake handle; 9. Brake cable; 10. Second check valve; 11. First check valve; 12. Brake control module; 13. Second accumulator; 14. First accumulator; 15. Emergency stop brake valve; 16. Second brake control valve unit; 17. First brake control valve unit; 18. Fourth switching valve; 19. Third switching valve; 20. Second switching valve; 21. First switching valve; 22. Fourth main drive wheel; 23. Third main drive wheel; 24. Second main drive wheel; 25. First main drive wheel; 26. First brake controller; 27. Second brake controller; 28. Cut-off valve; 29. ​​First servo valve; 30. Second servo valve. Detailed Implementation

[0060] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0061] An embodiment of a control system for an aircraft braking system according to the present invention, such as... Figure 1As shown, it includes: a pedal displacement detection module, a brake control valve module 12, a manual brake drive module, a pressure supply module, a brake control module, an automatic brake selection switch 1, and a pressure conversion module. The pedal displacement detection module is used to detect the brake command signals corresponding to the pilot's left pedal, pilot's right pedal, co-pilot's left pedal, and co-pilot's right pedal. The brake control valve module is used to control the flow of hydraulic oil in the hydraulic systems of the main landing gears on both sides of the aircraft and output hydraulic pressure. The manual brake drive module is used to drive the emergency stop brake valve to open. The pressure supply module is used to supply hydraulic oil to the brake control valve module and the emergency stop brake valve. The brake control module 12 is used for... Based on the brake command signals from the driver's left foot pedal, driver's right foot pedal, passenger's left foot pedal, and passenger's right foot pedal, the system controls the on / off state of the brake control valve module and outputs hydraulic pressure. Automatic brake selection switch 1 is used to input its position signal to the brake control module, whereby the brake control module provides a lock-in voltage to the automatic brake selection switch 1. The pressure conversion module outputs brake pressure based on a preset conversion pressure, the hydraulic pressure from the brake control valve and the emergency stop brake valve, and provides this brake pressure to the hydraulic system of the main engine wheel for braking.

[0062] For example, such as Figure 1 As shown, in one specific embodiment, the pedal displacement detection module includes: a first pedal sensor unit 2, a second pedal sensor unit 3, a third pedal sensor unit 4, and a fourth pedal sensor unit 5. The first pedal sensor unit 2 is used to detect the brake command signal of the driver's left pedal; the second pedal sensor unit 3 is used to detect the brake command signal of the driver's right pedal; the third pedal sensor unit 4 is used to detect the brake command signal of the passenger's left pedal; and the fourth pedal sensor unit 5 is used to detect the brake command signal of the passenger's right pedal. The brake command signal includes a first brake command signal and a second brake command signal. Each of the first pedal sensor unit 2, second pedal sensor unit 3, third pedal sensor unit 4, and fourth pedal sensor unit 5 includes a first displacement sensor and a second displacement sensor. The first displacement sensor is used to detect the first brake command signal corresponding to the pedal, and the second displacement sensor is used to detect the second brake command signal corresponding to the pedal.

[0063] For example, such as Figure 1 and Figure 2As shown, in one specific embodiment, the brake control module 12 includes: a first brake controller 26 and a second brake controller 27. The first brake controller 26 and the second brake controller 27 are connected via hardwire or bus communication. The first brake controller 26 is used to receive a first brake command signal detected by the first displacement sensor corresponding to the first pedal sensor unit 2, the second pedal sensor unit 3, the third pedal sensor unit 4, and the third pedal sensor unit 5. The second brake controller 27 is used to receive a second brake command signal detected by the second displacement sensor corresponding to the first pedal sensor unit 2, the second pedal sensor unit 3, the third pedal sensor unit 4, and the third pedal sensor unit 5.

[0064] For example, such as Figure 1 As shown, in one specific embodiment, the brake control valve module includes: a first brake control valve unit 17 and a second brake control valve unit 16. The first brake control valve unit 17 and the second brake control valve unit 16 have the same structure, as shown below. Figure 3 As shown, both the first brake control valve unit 17 and the second brake control valve unit 16 include a shut-off valve 28, a first servo valve 29, and a second servo valve 30. The shut-off valve 28 of the first brake control valve unit 17 is used to control the on / off of the hydraulic oil in the hydraulic system of the left main engine wheel, and the first servo valve 29 and the second servo valve 30 of the first brake control valve unit 17 are used to output hydraulic pressure. The shut-off valve 28 of the second brake control valve unit 16 is used to control the on / off of the hydraulic oil in the hydraulic system of the right main engine wheel, and the first servo valve 29 and the second servo valve 30 of the second brake control valve unit 16 are used to output hydraulic pressure. When the brake control module 12 receives a first brake command signal or a second brake command signal, the brake control module 12 controls the shut-off valves corresponding to the first brake control valve unit 17 and the second brake control valve unit 16 to open, and controls the servo valves corresponding to the first brake control valve unit 17 and the second brake control valve unit 16 to output the corresponding hydraulic pressure.

[0065] For example, such as Figure 1As shown, in one specific embodiment, the pressure supply module includes: a first pressure supply unit and a second pressure supply unit. The first pressure supply unit includes: a first hydraulic source 6, a first check valve 11, and a first accumulator 14 connected in sequence. The first hydraulic source 6 supplies hydraulic oil to the first accumulator 14 through the first check valve 11. The output end of the first accumulator 14 is connected to a first brake control unit 17 and a stop emergency brake valve 15, respectively. The second pressure supply unit includes: a second hydraulic source 7, a second check valve 10, and a second accumulator 13 connected in sequence. The second hydraulic source 7 supplies hydraulic oil to the second accumulator 13 through the second check valve 10. The output end of the second accumulator 13 is connected to a second brake control unit 16 and a stop emergency brake valve 15, respectively. The first brake controller 26 is used to ensure that the pressure signal of the first hydraulic source 6 in the first pressure supply unit is less than or equal to the brake pressure gate. When the pressure signal of the first hydraulic source 6 is greater than the brake pressure threshold, the first accumulator 14 of the first pressure supply unit supplies hydraulic oil to the first brake control valve unit 17 and the emergency brake valve. The second brake controller 27 controls the second accumulator 13 of the second pressure supply unit to supply hydraulic oil to the second brake control valve unit 16 and the emergency brake valve when the pressure signal of the second hydraulic source 7 of the second pressure supply unit is less than or equal to the brake pressure threshold. It also controls the second hydraulic source 7 of the second pressure supply unit to supply hydraulic oil to the second brake control valve unit 16 and the emergency brake valve when the pressure signal of the second hydraulic source 7 of the second pressure supply unit is greater than the brake pressure threshold. In this embodiment, the brake pressure threshold is 2000 psi.

[0066] For example, such as Figure 1As shown, in one specific embodiment, the pressure conversion module includes four pressure conversion valves, which are sequentially designated as a first conversion valve 21, a second conversion valve 20, a third conversion valve 19, and a fourth conversion valve 18. The inlet of the first conversion valve 21 is connected to the outlet of the first servo valve 29 corresponding to the first brake control unit 17 and the outlet of the emergency stop valve 15. The inlet of the second conversion valve 20 is connected to the outlet of the second servo valve 30 corresponding to the first brake control unit 17 and the outlet of the emergency stop valve 15. The inlet of the third conversion valve 19 is connected to the outlet of the first servo valve 29 corresponding to the second brake control unit 16 and the outlet of the emergency stop valve 18. The outlet of valve 5 is connected, the inlet of the fourth switching valve 18 is connected to the outlet of the second servo valve 30 corresponding to the second brake control unit 16, and the outlet of the emergency stop brake valve 15; the outlet of each pressure switching valve is connected to the hydraulic oil inlet of the hydraulic system of a main engine wheel, that is, the outlet of the first switching valve 21 is connected to the hydraulic oil inlet of the hydraulic system of the first main engine wheel 25, the outlet of the second switching valve 20 is connected to the hydraulic oil inlet of the hydraulic system of the second main engine wheel 24; the outlet of the third switching valve 19 is connected to the hydraulic oil inlet of the hydraulic system of the third main engine wheel 23, and the outlet of the fourth switching valve 18 is connected to the hydraulic oil inlet of the hydraulic system of the fourth main engine wheel 22.

[0067] For example, such as Figure 1 As shown, in one specific embodiment, the manual brake drive module includes: a brake handle 8, which is connected to a stop emergency brake valve 15 via a brake cable 9, wherein the stop emergency brake valve 15 is used to output hydraulic pressure according to the displacement of the brake cable 9.

[0068] Working principle of automatic braking

[0069] Automatic Braking Selector Switch 1 is electrically connected to the brake control module. After the aircraft taxis out, the pilot selects to turn Automatic Braking Selector Switch 1 to the RTO position. The brake control module receives the RTO position signal from Automatic Braking Selector Switch 1. When the aircraft is on the ground, the brake control module provides a locking voltage to Automatic Braking Selector Switch 1 to lock it in the RTO position. After the aircraft takes off, the brake control module determines that the aircraft is in the air, disconnects the locking voltage, and Automatic Braking Selector Switch 1 returns to the OFF position. When the aircraft is in the air, the pilot selects Automatic Braking Selector Switch 1 to the landing position. The brake control module determines that the aircraft is in the air, provides a locking voltage to Automatic Braking Selector Switch 1 to lock it in the landing position. When the aircraft touches down and the wheel speed matches the aircraft speed, constant deceleration braking is implemented according to the deceleration rate of the landing position. During automatic braking, when the pilot depresses the accelerator pedals, the brake control module determines that the accelerator pedals are depressed, disconnects the locking voltage, and Automatic Braking Selector Switch 1 returns to the OFF position.

[0070] A control method for an aircraft braking system, such asFigure 4 and Figure 5 As shown, it includes:

[0071] S1. Control the aircraft to engage automatic braking;

[0072] Specifically, based on the landing gear signal input by the automatic braking selection switch 1, the automatic braking selection switch 1 is locked in the landing gear until the aircraft is on the ground, at which point the aircraft is controlled to enter automatic braking.

[0073] For example, in one specific embodiment, after receiving the landing gear signal input by the automatic braking selection switch 1, the first brake controller of the brake control module provides a locking voltage to lock the automatic braking selection switch 1 in the landing gear until the aircraft is on the ground, and then controls the aircraft to brake at a constant deceleration rate to realize the aircraft entering automatic braking.

[0074] S2. Obtain the first brake command signal and the second brake command signal corresponding to each pedal;

[0075] Specifically, the first brake command signal and the second brake command signal corresponding to the driver's left foot pedal, driver's right foot pedal, passenger's left foot pedal, and passenger's right foot pedal are obtained respectively.

[0076] For example, in one specific embodiment, the first brake command signal of the driver's left foot pedal is detected by the first displacement sensor of the first pedal sensor unit 2; the first brake command signal of the driver's right foot pedal is detected by the first displacement sensor of the second pedal sensor unit 3; the first brake command signal of the passenger's left foot pedal is detected by the first displacement sensor of the third pedal sensor unit 4; the first brake command signal of the passenger's right foot pedal is detected by the first displacement sensor of the fourth pedal sensor unit 5; the second brake command signal of the driver's left foot pedal is detected by the second displacement sensor of the first pedal sensor unit 2; the second brake command signal of the driver's right foot pedal is detected by the second displacement sensor of the second pedal sensor unit 3; the second brake command signal of the passenger's left foot pedal is detected by the second displacement sensor of the third pedal sensor unit 4; and the second brake command signal of the passenger's right foot pedal is detected by the second displacement sensor of the fourth pedal sensor unit 5.

[0077] At this point, the first and second brake command signals corresponding to the driver's left pedal, driver's right pedal, passenger's left pedal, and passenger's right pedal can be obtained.

[0078] S3, Output pedal command signals for each pedal;

[0079] Specifically, the maximum value of the first command signals corresponding to the driver's left pedal and the passenger's left pedal is taken as the first pedal command signal; the maximum value of the first command signals corresponding to the driver's right pedal and the passenger's right pedal is taken as the second pedal command signal; the maximum value of the second command signals corresponding to the driver's left pedal and the passenger's left pedal is taken as the third pedal command signal; and the maximum value of the second command signals corresponding to the driver's right pedal and the passenger's right pedal is taken as the fourth pedal command signal.

[0080] For example, in one specific embodiment, the first brake controller 26 compares the received first command signals corresponding to the driver's left pedal and the passenger's left pedal, and takes the maximum value of the first command signals corresponding to the driver's left pedal and the passenger's left pedal as the first pedal command signal; the first brake controller 26 compares the first command signals corresponding to the driver's right pedal and the passenger's right pedal, and takes the maximum value of the first command signals corresponding to the driver's right pedal and the passenger's right pedal as the second pedal command signal.

[0081] For example, in one specific embodiment, the second brake controller 27 compares the received second command signals corresponding to the driver's left pedal and the passenger's left pedal, and takes the maximum value of the second command signals corresponding to the driver's left pedal and the passenger's left pedal as the third pedal command signal; the second brake controller 27 compares the received second command signals corresponding to the driver's right pedal and the passenger's right pedal, and takes the maximum value of the second command signals corresponding to the driver's right pedal and the passenger's right pedal as the fourth pedal command signal.

[0082] S4. Control the opening of the shut-off valve, release the automatic brake, and output hydraulic pressure from the servo valve;

[0083] Specifically, the first brake controller and the second brake controller determine the state of each pedal based on the corresponding pedal command signal and the pedal depressing threshold value. The first brake controller and the second brake controller share the pedal state and output the corresponding pedal command signal value. Based on the pedal command signal value, they control the opening and closing of the shut-off valve of the corresponding brake control valve unit to release the automatic brake. They also control the hydraulic pressure output by the servo valves corresponding to the first brake control valve unit and the second brake control valve unit.

[0084] For example, in one specific embodiment, the specific steps of S4 are as follows:

[0085] Step S41: The first brake controller determines the driver's pedal status corresponding to the first pedal command signal, the second pedal command signal, and the corresponding pedal depressing threshold value. The second brake controller determines the passenger's pedal status corresponding to the third pedal command signal, the fourth pedal command signal, and the corresponding pedal depressing threshold value. The pedal status includes depressing and not depressing. In one specific embodiment, step S41 is as follows: The first brake controller 26 determines whether the driver's left pedal corresponding to the first pedal command signal is depressed based on the first pedal command signal and the pedal depressing threshold value. If the first pedal command signal is greater than or equal to the pedal depressing threshold value, then the driver's left pedal corresponding to the first pedal command signal is depressed; otherwise, if the first pedal command signal is less than the pedal depressing threshold value, then the driver's left pedal corresponding to the first pedal command signal is not depressed. The first brake controller 26 determines whether the driver's right foot pedal corresponding to the second pedal command signal is pressed based on the second pedal command signal and the pedal pressing threshold value. If the second pedal command signal is greater than or equal to the pedal pressing threshold value, then it is determined that the driver's right foot pedal corresponding to the second pedal command signal is pressed; if the second pedal command signal is less than the pedal pressing threshold value, then it is determined that the driver's right foot pedal corresponding to the second pedal command signal is not pressed. The second brake controller 27 determines whether the passenger's left foot pedal corresponding to the third foot pedal command signal is pressed based on the third foot pedal command signal and the foot pedal depressing threshold value. If the third foot pedal command signal is greater than or equal to the foot pedal depressing threshold value, then it is determined that the passenger's left foot pedal corresponding to the third foot pedal command signal is pressed; otherwise, if the third foot pedal command signal is less than the foot pedal depressing threshold value, then it is determined that the passenger's left foot pedal corresponding to the third foot pedal command signal is not pressed. The second brake controller 27 determines whether the passenger's right foot pedal corresponding to the fourth foot pedal command signal is pressed based on the fourth foot pedal command signal and the foot pedal depressing threshold value. If the fourth foot pedal command signal is greater than or equal to the foot pedal depressing threshold value, then it is determined that the passenger's right foot pedal corresponding to the fourth foot pedal command signal is pressed; otherwise, if the fourth foot pedal command signal is less than the foot pedal depressing threshold value, then it is determined that the passenger's right foot pedal corresponding to the fourth foot pedal command signal is not pressed.

[0086] In step S42, the first brake controller and the second brake controller share the acquired pedal states of the driver and passenger. The first brake controller outputs the pedal command signal value of the driver's pedal based on the passenger's pedal state, and the second brake controller outputs the pedal command signal value of the passenger's pedal based on the driver's pedal state. In one specific implementation, step S42 specifically involves: the first brake controller 26 sending the driver's left pedal depress / not depress signal corresponding to the first pedal command signal and the driver's right pedal depress / not depress signal corresponding to the second pedal command signal to the second brake controller 27; the second brake controller 27 then sends the passenger's left pedal depress / not depress signal corresponding to the third pedal command signal and the passenger's right pedal depress / not depress signal corresponding to the fourth pedal command signal to the first brake controller 26. Specifically, if the passenger's left pedal corresponding to the third pedal command signal received by the first brake controller 26 is depressed, a first pedal command signal is output; conversely, if the passenger's left pedal corresponding to the third pedal command signal received by the first brake controller 26 is not depressed, a first pedal command signal of 0 is output. If the passenger's right pedal corresponding to the fourth pedal command signal received by the first brake controller 26 is depressed, a second pedal command signal is output; conversely, if the passenger's right pedal corresponding to the fourth pedal command signal received by the first control board is not depressed, a second pedal command signal of 0 is output. Similarly, if the driver's left pedal corresponding to the first pedal command signal received by the second brake controller 27 is depressed, a third pedal command signal is output; conversely, if the driver's left pedal corresponding to the first pedal command signal received by the second brake controller 27 is not depressed, a third pedal command signal of 0 is output. If the driver's right foot pedal corresponding to the second pedal command signal received by the second brake controller 27 is depressed, the fourth pedal command signal is output; if the driver's right foot pedal corresponding to the second pedal command signal received by the second brake controller 27 is not depressed, the fourth pedal command signal is output as 0.

[0087] Step S43: When at least one pedal is in the depressed state, the first brake controller controls the automatic brake to be released.

[0088] Step S44: Based on the signal value of the pedal command signal from the driver's pedal, control the opening and closing of the shut-off valve of the first brake control valve unit; based on the signal value of the pedal command signal from the passenger's pedal, control the opening and closing of the shut-off valve of the second brake control valve unit, and control the hydraulic pressure output by the servo valves corresponding to the first and second brake control valve units; Specific steps of step S44: If the first pedal command signal or the second pedal command signal calculated by the first brake controller 26 is not 0, then the first brake controller 26 controls the shut-off valve 28 of the first brake control valve unit 17 to open; conversely, if the first pedal command signal or the second pedal command signal calculated by the first brake controller 26 is both 0, then the first brake controller 26 controls the shut-off valve 28 of the first brake control valve unit 17 to close. The first pedal command signal controls the first servo valve 29 of the first brake control valve unit 17, and the second pedal command signal controls the second servo valve 30 of the first brake control valve unit 17 to output the corresponding hydraulic pressure. If the third or fourth pedal command signal calculated by the second brake controller 27 is not zero, then the second brake controller 27 controls the shut-off valve 28 of the second brake control valve unit 16 to open; conversely, if both the third and fourth pedal command signals calculated by the second brake controller 27 are zero, then the second brake controller 27 controls the shut-off valve 28 of the second brake control valve unit 16 to close. The third pedal command signal controls the first servo valve 29 of the second brake control valve unit 16, and the fourth pedal command signal controls the second servo valve 30 of the second brake control valve unit 16 to output the corresponding hydraulic pressure.

[0089] In one specific embodiment, the pedal depressing threshold is defined as 10% of the total pedal displacement.

[0090] S5, outputs braking pressure and controls the hydraulic system of the main wheel to brake the main wheel;

[0091] Specifically, the system detects the fault status of the braking system, which includes: the braking system has not lost its braking ability, has lost less than half of its braking ability, has lost half of its braking ability, and has lost more than half of its braking ability. When the braking system loses half or more of its braking ability, the brake handle 8 is used for emergency braking. Based on the hydraulic pressure output by the servo valve, the hydraulic pressure output by the emergency brake valve, and the preset conversion pressure, the system outputs braking pressure and controls the hydraulic system of the main wheel to brake the main wheel.

[0092] For example, in one specific embodiment, if the difference between the hydraulic pressure output by the servo valve and the hydraulic pressure output by the emergency stop valve 15 is greater than or equal to a preset conversion pressure, then the hydraulic pressure output by the servo valve is used as the braking pressure; if the difference between the hydraulic pressure output by the emergency stop valve 15 and the hydraulic pressure output by the servo valve is greater than or equal to the preset conversion pressure, then the hydraulic pressure output by the emergency stop valve 15 is used as the braking pressure; if the absolute value of the difference between the hydraulic pressure output by the servo valve and the hydraulic pressure output by the emergency stop valve 15 is less than the conversion pressure, then the braking pressure output at the previous moment is used as the current braking pressure, wherein the conversion pressure is 100 psi.

[0093] It should be noted that the emergency stop valve 15 outputs corresponding hydraulic pressure based on the displacement of the brake cable 9. The relationship between the displacement of the cable 9 and the hydraulic pressure is as follows: Figure 6 As shown, the relationship between the displacement of the brake cable 9 and the hydraulic pressure output by the emergency stop valve 15 is a three-stage relationship: the first stage is 0%–10%, the second stage is 10%–50%, the third stage is 50%–75%, the fourth stage is 75%–90%, and the fifth stage is 90%–100%. In this embodiment, the hydraulic pressure output by the emergency stop valve 15 in the first stage is 0; the hydraulic pressure output by the emergency stop valve 15 in the second stage is linear, with 10% corresponding to a hydraulic pressure of 300 psi and 50% corresponding to a hydraulic pressure of 750 psi; the hydraulic pressure output by the emergency stop valve 15 in the third stage is linear, with 50% corresponding to a hydraulic pressure of 750 psi and 75% corresponding to a hydraulic pressure of 1500 psi; the hydraulic pressure output in the fourth stage is 1500 psi; and the hydraulic pressure output in the fifth stage is 3000 psi.

[0094] Taking the first main wheel 25 as an example, if the difference between the hydraulic pressure output by the first servo valve 29 corresponding to the first brake control unit 17 and the hydraulic pressure output by the emergency stop brake valve 15 is greater than or equal to the preset conversion pressure, then the hydraulic pressure output by the first servo valve 29 of the first brake control unit 17 is used as the braking pressure of the first main wheel 25. If the difference between the hydraulic pressure output by the emergency stop brake valve 15 and the hydraulic pressure output by the first servo valve 29 of the first brake control unit 17 is greater than or equal to the preset conversion pressure, then the hydraulic pressure output by the emergency stop brake valve 15 is used as the braking pressure of the first main wheel 25. If the absolute value of the difference between the hydraulic pressure output by the first servo valve 29 of the first brake control unit 17 and the hydraulic pressure output by the emergency stop brake valve 15 is less than the conversion pressure, then the braking pressure output at the previous moment is used as the current braking pressure of the first main wheel 25.

[0095] Taking the second main drive wheel 24 as an example, if the difference between the hydraulic pressure output by the second servo valve 30 corresponding to the first brake control unit 17 and the hydraulic pressure output by the emergency stop brake valve 15 is greater than or equal to the preset conversion pressure, then the hydraulic pressure output by the second servo valve 30 corresponding to the first brake control unit 17 is used as the braking pressure of the second main drive wheel 24. If the difference between the hydraulic pressure output by the emergency stop brake valve 15 and the hydraulic pressure output by the second servo valve 30 is greater than or equal to the preset conversion pressure, then the hydraulic pressure output by the emergency stop brake valve 15 is used as the braking pressure of the second main drive wheel 24. If the absolute value of the difference between the hydraulic pressure output by the second servo valve 30 corresponding to the first brake control unit 17 and the hydraulic pressure output by the emergency stop brake valve 15 is less than the conversion pressure, then the braking pressure output at the previous moment is used as the current braking pressure of the second main drive wheel 24.

[0096] Taking the third main engine wheel 23 as an example, if the difference between the hydraulic pressure output by the first servo valve 29 corresponding to the second brake control unit 16 and the hydraulic pressure output by the emergency stop brake valve 15 is greater than or equal to the preset conversion pressure, then the hydraulic pressure output by the first servo valve 29 of the second brake control unit 16 is used as the braking pressure of the third main engine wheel 23. If the difference between the hydraulic pressure output by the emergency stop brake valve 15 and the hydraulic pressure output by the first servo valve 29 of the second brake control unit 16 is greater than or equal to the preset conversion pressure, then the hydraulic pressure output by the emergency stop brake valve 15 is used as the braking pressure of the third main engine wheel 23. If the absolute value of the difference between the hydraulic pressure output by the first servo valve 29 of the second brake control unit 16 and the hydraulic pressure output by the emergency stop brake valve 15 is less than the conversion pressure, then the braking pressure output at the previous moment is used as the current braking pressure of the third main engine wheel 23.

[0097] Taking the fourth main engine wheel 22 as an example, if the difference between the hydraulic pressure output by the second servo valve 30 corresponding to the second brake control unit 16 and the hydraulic pressure output by the emergency stop brake valve 15 is greater than or equal to the preset conversion pressure, then the hydraulic pressure output by the second servo valve 30 corresponding to the second brake control unit 16 is used as the braking pressure of the fourth main engine wheel 22. If the difference between the hydraulic pressure output by the emergency stop brake valve 15 and the hydraulic pressure output by the second servo valve 30 corresponding to the second brake control unit 16 is greater than or equal to the preset conversion pressure, then the hydraulic pressure output by the emergency stop brake valve 15 is used as the braking pressure of the fourth main engine wheel 22. If the absolute value of the difference between the hydraulic pressure output by the second servo valve 30 corresponding to the second brake control unit 16 and the hydraulic pressure output by the emergency stop brake valve 15 is less than the conversion pressure, then the braking pressure output at the previous moment is used as the current braking pressure of the fourth main engine wheel 22.

[0098] It also includes: braking control steps in case of aircraft braking system failure: when the first brake controller or the second brake controller fails, it is determined that the braking system has lost half of its braking capacity; when the shut-off valve of the first brake control valve or the shut-off valve of the second brake control valve fails, it is determined that the braking system has lost half of its braking capacity; when two or more servo valves inside the first brake control valve and the second brake control valve fail, it is determined that the braking system has lost half of its braking capacity; when all four displacement sensor signals received by the first brake controller fail, or when all four displacement sensor signals received by the second first brake controller fail, it is determined that the braking system has lost half of its braking capacity; when the braking system has lost half or more of its braking capacity, emergency braking is performed using the brake handle 8; when the braking system has not lost its braking capacity, or has lost less than half of its braking capacity, the foot brake is used.

[0099] When the aircraft is stopped, the pilot manipulates the brake lever 8 to the maximum position. The brake lever 8 is mechanically locked in the maximum position, and the emergency stop brake valve 15 outputs 3000psi to the corresponding switching valve, and finally to the main landing gear, so that the aircraft stops.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A control method for an aircraft braking system, characterized in that, include: Based on the landing gear signal input from the automatic braking switch, the automatic braking selector switch is locked in the landing gear until the aircraft is on the ground, at which point the aircraft is controlled to enter automatic braking. The first brake command signal and the second brake command signal corresponding to the driver's left foot pedal, driver's right foot pedal, passenger's left foot pedal and passenger's right foot pedal are respectively acquired; The maximum value of the first command signals corresponding to the driver's left foot pedal and the passenger's left foot pedal is taken as the first foot pedal command signal. The maximum value of the first command signal corresponding to the driver's right foot pedal and the passenger's right foot pedal is used as the second foot pedal command signal. The maximum value of the second command signals corresponding to the driver's left pedal and the passenger's left pedal is taken as the third pedal command signal; the maximum value of the second command signals corresponding to the driver's right pedal and the passenger's right pedal is taken as the fourth pedal command signal. The first and second brake controllers determine the pedal state for each pedal based on the corresponding pedal command signal and pedal depressing threshold value. The first and second brake controllers share the pedal state and output the corresponding pedal command signal value. Based on the pedal command signal value, they control the on / off state of the cut-off valve of the corresponding brake control valve unit to release the automatic brake. They also control the hydraulic pressure output by the servo valves corresponding to the first and second brake control valve units. Specifically, the first brake controller determines the driver's pedal state corresponding to the first and second pedal command signals based on the first and second pedal command signals and the corresponding pedal depressing threshold value. The second brake controller determines the pedal state of the third and fourth pedal command signals based on the third and fourth pedal command signals and the corresponding pedal depressing threshold value. The system controls the pedal status of the passenger side corresponding to the signal, including whether the pedal is depressed or not. The first and second brake controllers share the acquired pedal status information from the driver and passenger sides. The first brake controller outputs the pedal command signal value for the driver's pedal based on the passenger's pedal status, and the second brake controller outputs the pedal command signal value for the passenger side based on the driver's pedal status. When at least one pedal is depressed, the first brake controller releases the automatic brake. Based on the pedal command signal value for the driver's pedal, the system controls the on / off state of the cut-off valve of the first brake control valve unit. Based on the pedal command signal value for the passenger side, the system controls the on / off state of the cut-off valve of the second brake control valve unit, and controls the hydraulic pressure output by the servo valves corresponding to the first and second brake control valve units. Detect the fault status of the braking system. Fault status includes: loss of less than half of the braking capacity, loss of half of the braking capacity, and loss of more than half of the braking capacity. When the braking system loses half or more of its braking capacity, use the brake lever for emergency braking. Based on the hydraulic pressure output by the servo valve, the hydraulic pressure output by the emergency stop brake valve, and the preset switching pressure, a braking pressure is output, and the hydraulic system of the main engine wheel is controlled to brake the main engine wheel according to the braking pressure. Specifically, if the difference between the hydraulic pressure output by the servo valve and the hydraulic pressure output by the emergency stop brake valve is greater than or equal to the preset switching pressure, then the hydraulic pressure of the servo valve is used as the braking pressure; if the difference between the hydraulic pressure output by the emergency stop brake valve and the hydraulic pressure output by the servo valve is greater than or equal to the preset switching pressure, then the hydraulic pressure output by the emergency stop brake valve is used as the braking pressure; if the absolute value of the difference between the hydraulic pressure output by the servo valve and the hydraulic pressure output by the emergency stop brake valve is less than the switching pressure, then the braking pressure output at the previous moment is used as the current braking pressure.

2. The control method for an aircraft braking system according to claim 1, characterized in that, Aircraft braking systems include: The pedal displacement detection module is used to detect the brake command signals corresponding to the driver's left pedal, driver's right pedal, passenger's left pedal, and passenger's right pedal. The brake control valve module is used to control the flow of hydraulic oil in the hydraulic systems of the main landing gear on both sides of the aircraft and to output hydraulic pressure. The manual brake drive module is used to open the emergency stop brake valve. The pressure supply module is used to supply hydraulic oil to the brake control valve module and the emergency brake valve for shutdown. The brake control module is used to control the opening and closing of the brake control valve module and output hydraulic pressure based on the brake command signals from the driver's left foot pedal, the driver's right foot pedal, the passenger's left foot pedal, and the passenger's right foot pedal. An automatic brake selection switch is used to input the position signal of the automatic brake selection switch to the brake control module, wherein the brake control module is used to provide a locking voltage to the automatic brake selection switch; It also includes a pressure conversion module, which outputs braking pressure based on the preset conversion pressure, the hydraulic pressure output by the brake control valve and the emergency stop brake valve, and provides the braking pressure to the hydraulic system of the main engine wheel to brake the main engine wheel.

3. The control method for an aircraft braking system according to claim 2, characterized in that, The foot pedal displacement detection module includes: The first pedal sensor unit is used to detect the brake command signal from the driver's left pedal; The second pedal sensor unit is used to detect the brake command signal from the driver's right pedal; The third pedal sensor unit is used to detect the brake command signal from the passenger's left pedal; And a fourth pedal sensor unit, used to detect the brake command signal of the passenger's right pedal; The braking command signal includes a first braking command signal and a second braking command signal. The first pedal sensor unit, the second pedal sensor unit, the third pedal sensor unit, and the fourth pedal sensor unit all include a first displacement sensor and a second displacement sensor. The first displacement sensor is used to detect the first braking command signal corresponding to the pedal, and the second displacement sensor is used to detect the second braking command signal corresponding to the pedal.

4. The control method for an aircraft braking system according to claim 3, characterized in that, The brake control module includes: The first brake controller is used to receive the first brake command signal detected by the first displacement sensor corresponding to the first pedal sensor unit, the second pedal sensor unit, the third pedal sensor unit, and the fourth pedal sensor unit. The second brake controller is used to receive the second brake command signal detected by the second displacement sensor corresponding to the first pedal sensor unit, the second pedal sensor unit, the third pedal sensor unit, and the fourth pedal sensor unit. The first brake controller and the second brake controller are connected in communication.

5. The control method for an aircraft braking system according to claim 4, characterized in that, The brake control valve module includes: a first brake control valve unit and a second brake control valve unit. The first brake control valve unit and the second brake control valve unit have the same structure, both including a shut-off valve and a servo valve. The shut-off valve of the first brake control valve unit is used to control the on / off of hydraulic oil in the hydraulic system of the left main engine wheel, and the servo valve of the first brake control valve unit is used to output hydraulic pressure. The shut-off valve of the second brake control valve unit is used to control the on / off of hydraulic oil in the hydraulic system of the right main engine wheel, and the servo valve of the second brake control valve unit is used to output hydraulic pressure. Specifically, when the brake control module receives a first brake command signal or a second brake command signal, the brake control module controls the corresponding shut-off valves of the first brake control valve unit and the second brake control valve unit to open, and controls the corresponding servo valves of the first brake control valve unit and the second brake control valve unit to output the corresponding hydraulic pressure.

6. The control method for an aircraft braking system according to claim 4, characterized in that, The pressure supply module includes: a first pressure supply unit and a second pressure supply unit; Both the first pressure supply unit and the second pressure supply unit include: a hydraulic source, a check valve, and an accumulator connected in sequence. The hydraulic source supplies hydraulic oil to the accumulator through the check valve. The output end of the accumulator of the first pressure supply unit is connected to the first brake control valve unit and the emergency stop brake valve, respectively. The output end of the accumulator of the second pressure supply unit is connected to the second brake control valve unit and the emergency stop brake valve, respectively. The first brake controller is used to control the accumulator of the first pressure supply unit to provide hydraulic oil to the first brake control valve unit and the emergency stop brake valve when the pressure signal of the hydraulic source of the first pressure supply unit is less than or equal to the brake pressure threshold; and to control the hydraulic source of the first pressure supply unit to provide hydraulic oil to the first brake control valve unit and the emergency stop brake valve when the pressure signal of the hydraulic source of the first pressure supply unit is greater than the brake pressure threshold. The second brake controller is used to control the accumulator of the second pressure supply unit to provide hydraulic oil to the second brake control valve unit and the emergency stop brake valve when the pressure signal of the hydraulic source of the second pressure supply unit is less than or equal to the brake pressure threshold; and to control the hydraulic source of the second pressure supply unit to provide hydraulic oil to the second brake control valve unit and the emergency stop brake valve when the pressure signal of the hydraulic source of the second pressure supply unit is greater than the brake pressure threshold.

7. The control method for an aircraft braking system according to claim 2, characterized in that, The pressure conversion module includes: multiple pressure conversion valves, the outlet of each pressure conversion valve is connected to the hydraulic oil inlet of the hydraulic system of the main engine wheel, and the inlet of each pressure conversion valve is connected to the outlet of the brake control valve module and the emergency brake valve for shutdown.

8. The control method for an aircraft braking system according to claim 2, characterized in that, The manual brake drive module includes a brake handle connected to a stop emergency brake valve via a steel cable, wherein the stop emergency brake valve is used to output hydraulic pressure according to the displacement of the steel cable.

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