Fault detection method for airplane front wheel turning control valve

Abstract

According to the aircraft front wheel turning control valve fault detection method, a fault detection program resides in a turning control unit, and the fault detection program comprises a fault detection condition judgment module and a fault detection instruction sending module. The fault detection condition judgment module is used for receiving a pressure signal of a hydraulic system, a wheel load signal of an undercarriage folding and unfolding system, a speed signal of a brake system, a turning release signal of a turning release switch and a fault signal of a front wheel turning system; the fault detection instruction sending module sends a turn-off instruction to a turn-off valve of the turning control valve and sends a turning instruction to a servo valve of the turning control valve, if the servo valve cannot control the action of a turning mechanism and enables front wheels not to deflect, it is indicated that the turn-off valve is in a normal working state, and if the servo valve controls the action of the turning mechanism and enables the front wheels to deflect, it is indicated that the turn-off valve is in a normal working state. And indicating that the shut-off valve is in a hidden fault state.

Description

Technical Field

[0001] The present application relates to the field of aircraft design technology, and further to aircraft front wheel turning design technology, and specifically to a method for detecting a fault of an aircraft front wheel turning control valve. Background Art

[0002] The front wheel turning system of the aircraft is driven by electric wire control hydraulics. Its technical features are that the front wheel turning system is linked with the hydraulic system to receive hydraulic pressure signals, linked with the landing gear retraction and extension system to receive wheel load signals, and linked with the brake system to receive speed signals. After the turning control unit makes logical judgments and calculates the control law, it outputs valve control command signals to the turning control valve. The shut-off valve of the turning control valve performs hydraulic on-off control, and the servo valve of the turning control valve performs hydraulic flow control, so that the turning mechanism drives the front wheel to deflect. The front wheel angle feedback sensor detects the change in the front wheel deflection angle and feeds it back to the turning control unit. At the same time, the turning control unit realizes system fault monitoring through the fault detection function. When the system is detected to be abnormal or failed, the shut-off valve of the turning control valve is cut off to put the system in fail-safe mode to improve system safety. However, the working characteristic of the front wheel turning system is that the system is basically in a power turning state in the ground stage, that is, the shut-off valve of the turning control valve in the ground state is always in the energized and connected state. Since the shut-off valve is in the normally closed fault mode, it does not affect the normal turning function. Therefore, the normally closed fault mode of the shut-off valve is a hidden fault. Although it does not affect the normal turning function, when the system is abnormal, the system cannot cut off the hydraulic energy by shutting off the power of the shut-off valve to make the system enter the fail-safe working mode. If the normally closed fault mode of the shut-off valve cannot be detected in time, the safety level of the front wheel turning system will be reduced. Therefore, the normally closed fault of the shut-off valve is detected in a reasonable and safe way, and the potential hidden fault is made explicit, which can improve the safety level of the system.

[0003] There are currently two ways to detect the normally closed fault of the shut-off valve. One is to set a pressure switch in the hydraulic oil circuit downstream of the shut-off valve control, and judge it by the high and low status of the hydraulic oil circuit detected by the pressure switch and the status of the shut-off valve valve control command signal. The other is to perform a self-check on the front wheel turning system after the landing gear is lowered during the landing phase of the aircraft. The turning control unit outputs a small angle turning command, and the system uses the front wheel angle feedback sensor to detect whether the actual deflection angle of the front wheel has changed to determine whether the shut-off valve is in the normally closed fault mode. The method of setting a pressure switch in the hydraulic oil circuit downstream of the shut-off valve control requires the additional integration of a pressure switch module in the turning control valve, which will increase the weight of the equipment and reduce the reliability of the equipment. There is a certain safety risk in the method of performing self-inspection by lowering the landing gear and then turning the system. First of all, this self-inspection method is achieved by sending a front wheel deflection command in the air and detecting the change in the front wheel deflection angle. Currently, the landing gear structure is equipped with a centering mechanism to ensure that the front wheel remains in a neutral position after leaving the ground. Therefore, when the front wheel deflection command is sent in the air, once the shut-off valve is in a normally closed fault, the front wheel will deflect in the air. This deflection may cause certain structural damage to the centering mechanism and affect the centering ability. If this deflection is uncontrollable, it will cause the front wheel to deflect at a large angle, causing the aircraft to deviate from the runway due to the front wheel not landing in the center, causing a catastrophic safety impact on the aircraft. Summary of the invention

[0004] The purpose of the present application is to provide a method for detecting a fault of an aircraft nose wheel turning control valve, which can conveniently detect whether a shut-off valve of the turning control valve has a fault.

[0005] A method for detecting a fault in a front wheel turning control valve of an aircraft, characterized in that it comprises the following contents: 1) there is an aircraft front wheel turning control valve fault detection system, the detection system comprises a hydraulic system interconnected with the front wheel turning system, a landing gear retraction and extension system, and a brake system, the front wheel turning system comprises a turning control unit, a turning control valve, a turning release switch, a front wheel angle feedback sensor, and a turning mechanism, the turning control valve comprises a shut-off valve and a servo valve, the turning control unit sends a turning instruction to the turning control valve, the shut-off valve of the turning control valve controls the hydraulic connection of the servo valve, the servo valve controls the turning mechanism to move, the front wheel deflects, and the feedback sensor detects the change in the front wheel deflection angle; 2) a fault detection program resides in the turning control unit, the fault detection program comprises a fault detection condition judgment module Block and fault detection instruction sending module; 3) The fault detection condition judgment module receives the pressure signal of the hydraulic system, the wheel load signal of the landing gear retraction and extension system, the speed signal of the brake system, the turn release signal of the turn release switch and the fault signal of the front wheel turning system. When the above signals meet the fault detection conditions, a fault detection instruction is issued; 4) According to the fault detection instruction, the fault detection instruction sending module sends a shut-off instruction to the shut-off valve of the turning control valve and sends a turning instruction to the servo valve of the turning control valve; 5) After the fault detection instruction is sent, if the servo valve cannot control the turning mechanism to prevent the front wheel from deflecting, it means that the shut-off valve is in a normal working state; 7) After the fault detection instruction is sent, if the servo valve controls the turning mechanism to cause the front wheel to deflect, it means that the shut-off valve is in a hidden fault state.

[0006] The aircraft front wheel turning control valve fault detection method is characterized in that the fault detection conditions include that the pressure signal of the hydraulic system is greater than the minimum working pressure of the turning system, the wheel load signal is "ground", the speed signal is lower than 5km / h, the turning release signal is "not released" and the front wheel turning system has no "failure" fault.

[0007] The aircraft front wheel turning control valve fault detection method is characterized in that, in step 3), when the fault detection condition judgment module fails to meet the fault detection conditions when the wheel load signal of the landing gear retraction and extension system, the speed signal of the brake system, the turn release signal of the turn release switch and the front wheel turning system fault signal do not meet the fault detection conditions, no fault detection instruction is issued and the front wheel turning system maintains the normal working mode.

[0008] The beneficial effect of the present application is that: through the turning control valve fault detection program, the shut-off valve normally closed fault mode detection function of the turning control valve can be realized on the basis of the typical hardware of the front wheel turning system. The method does not change the system hardware architecture, and can realize the "normally closed" invisible fault mode detection function of the shut-off valve only through later software development and upgrading, and has a strong system improvement capability. The fault detection condition judgment module in the fault detection program judges the hydraulic pressure signal and the turning system fault signal to ensure the effectiveness of the fault detection, and then judges through the wheel load signal, speed signal and turning release signal to avoid the implementation of fault detection during the operation process or towing process of the aircraft, and ensure the operational safety of the aircraft. The turning control valve fault detection method can make the potential normally closed hidden fault of the shut-off valve explicit, improve the system fault detection capability, and improve the safety level of the front wheel turning system, so as to ensure that when the system is abnormal or wrong, the shut-off valve of the turning control valve can be effectively cut off to achieve fault suppression, avoid the implementation of abnormal or wrong turning instructions, and reduce the safety impact of abnormal or wrong turning functions on the aircraft.

[0009] The present application is further described in detail below in conjunction with the accompanying drawings of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is the principle block diagram of the front wheel turning control valve fault detection method. DETAILED DESCRIPTION

[0011] Referring to the attached drawings, the aircraft nose wheel turning control valve fault detection method of the present application is to upgrade the software based on the aircraft nose wheel turning control valve fault detection system, such as Figure 1As shown, the detection system includes a hydraulic system interconnected with the front wheel turning system, a landing gear retracting and extending system, and a brake system. The front wheel turning system includes a turning control unit, a turning control valve, a turning release switch, a front wheel angle feedback sensor, and a turning mechanism. The turning control valve includes a shut-off valve and a servo valve. The turning control unit sends a turning command to the turning control valve. The shut-off valve of the turning control valve controls the hydraulic connection of the servo valve. The servo valve controls the turning mechanism to cause the front wheel to deflect. The feedback sensor detects the change in the front wheel deflection angle. The fault detection program resident in the turning control unit of the present application includes a fault detection condition judgment module and a fault detection instruction sending module. The fault detection condition judgment module receives a pressure signal of the hydraulic system, a wheel load signal of the landing gear retracting and extending system, a speed signal of the brake system, and a rotation signal of the turning release switch. The fault detection condition judgment module will issue a fault detection instruction only when the above signals meet the fault detection conditions, the pressure signal of the hydraulic system is greater than the minimum working pressure of the turning system, the wheel load signal is "ground", the speed signal is lower than 5km / h, the turning release signal is "not released" and the front wheel turning system has no "failure" fault; according to the fault detection instruction, the fault detection instruction sending module sends a shut-off instruction to the shut-off valve of the turning control valve and sends a turning instruction to the servo valve of the turning control valve; after the fault detection instruction is sent, if the servo valve cannot control the turning mechanism to prevent the front wheel from deflecting, it means that the shut-off valve is in a normal working state; after the fault detection instruction is sent, if the servo valve controls the turning mechanism to cause the front wheel to deflect, it means that the shut-off valve is in a hidden fault state.

[0012] When the fault detection condition judgment module fails to meet the fault detection conditions when the wheel load signal of the landing gear retraction and extension system, the speed signal of the brake system, the turn release signal of the turn release switch and the fault signal of the front wheel turning system, no fault detection instruction is issued and the front wheel turning system maintains the normal working mode.

[0013] The specific detection process is as follows: after the aircraft is powered on, the turning control unit is powered on and works, and the turning control unit receives hydraulic pressure signals, wheel load signals, aircraft speed signals and turning release signals. When the hydraulic pressure signal value is lower than the minimum working pressure of the turning system, the front wheel turning system enters the free steering mode, and the turning control unit continuously receives the pressure signal to determine whether it is greater than the minimum working pressure of the turning system. When the pressure signal is greater than the minimum working pressure of the turning system, the wheel load signal, aircraft speed signal and turning release signal are used to determine whether the aircraft state meets the fault detection condition. If the fault detection condition is not met, the fault detection instruction sending module will be directly skipped to enter the normal working mode of turning. When the fault detection condition is met, the fault detection instruction sending module sends a shut-off instruction to the shut-off valve of the turning control valve and sends a small angle turning instruction to the servo valve of the turning control valve. When the shut-off valve is under the shut-off instruction, the shut-off valve controls the hydraulic energy to not enter the servo valve to drive the turning mechanism to move, and the front wheel cannot be deflected; only when the shut-off valve is in a faulty state and the shut-off valve cannot shut off the hydraulic energy normally, the hydraulic energy normally enters the servo valve to drive the turning mechanism to move, causing the front wheel to deflect. During the detection, if the front wheel angle feedback sensor detects that the front wheel angle has changed, it means that the shut-off valve is in a faulty state; if the front wheel angle feedback sensor detects that the front wheel angle has not changed, it means that the shut-off valve is in a normal state.

Claims

1. A method for detecting a fault in an aircraft front wheel steering control valve, characterized in that The invention comprises the following contents: 1) there is a fault detection system for the front wheel turning control valve of an aircraft, the detection system comprises a hydraulic system interconnected with the front wheel turning system, a landing gear retraction and extension system, and a braking system, the front wheel turning system comprises a turning control unit, a turning control valve, a turning release switch, a front wheel angle feedback sensor, and a turning mechanism, the turning control valve comprises a shut-off valve and a servo valve, the turning control unit sends a turning command to the turning control valve, the shut-off valve of the turning control valve controls the hydraulic connection of the servo valve, the servo valve controls the turning mechanism to cause the front wheel to deflect, and the feedback sensor detects the change of the front wheel deflection angle; 2) a fault detection program resides in the turning control unit, the fault detection program comprises a fault detection condition judgment module and a fault detection instruction sending module block; 3) the fault detection condition judgment module receives the pressure signal of the hydraulic system, the wheel load signal of the landing gear retraction and extension system, the speed signal of the brake system, the turn release signal of the turn release switch and the fault signal of the front wheel turning system. When the above signals meet the fault detection conditions, a fault detection instruction is issued; 4) according to the fault detection instruction, the fault detection instruction sending module sends a shut-off instruction to the shut-off valve of the turning control valve and sends a turning instruction to the servo valve of the turning control valve; 5) after the fault detection instruction is sent, if the servo valve cannot control the turning mechanism to prevent the front wheel from deflecting, it means that the shut-off valve is in a normal working state; 6) after the fault detection instruction is sent, if the servo valve controls the turning mechanism to cause the front wheel to deflect, it means that the shut-off valve is in a hidden fault state.

2. The method for detecting a fault of an aircraft front wheel steering control valve according to claim 1, characterized in that: The fault detection conditions include that the pressure signal of the hydraulic system is greater than the minimum working pressure of the turning system, the wheel load signal is "ground", the speed signal is lower than 5km / h, the turning release signal is "not released" and there is no "failure" fault in the front wheel turning system.

3. The method for detecting a fault of an aircraft nose wheel steering control valve according to claim 1, characterized in that: In step 3), when the fault detection condition judgment module fails to meet the fault detection conditions when the wheel load signal of the landing gear retraction and extension system, the speed signal of the brake system, the turn release signal of the turn release switch and the fault signal of the front wheel turning system, no fault detection instruction is issued and the front wheel turning system maintains the normal working mode.

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