Aircraft front wheel turning hydraulic control system capable of achieving precise adjustment of shimmy damping

Abstract

The invention provides an airplane front wheel turning hydraulic control system capable of realizing precise adjustment of shimmy damping, which is characterized by comprising a direct-drive servo valve (2), a hydraulic lock (11), an electric proportional throttle valve (4), an oil supplementing loop (9), a safety loop (10), a back pressure control loop (12), a filter (1), a valve body, an actuator (7), a displacement sensor (6) and a controller (3), an oil path of an output cavity of the direct-driven servo valve (2) is respectively connected to two load cavities of the actuator (7); a hydraulic lock (11) is arranged in the middle of a loop of the direct-drive servo valve (2) and the actuator (7); a safety loop (10), an oil supplementing loop (9) and an electric proportional throttle valve (4) are arranged; the filter (1) is arranged at the oil inlet end of the direct-drive servo valve (2), and the back pressure control loop (12) is arranged at the oil return end of the direct-drive servo valve (2). The anti-pollution damper is higher in anti-pollution capacity, leakage of the load cavity is avoided, and the anti-pollution damper can adapt to different anti-swing working conditions.

Description

Technical Field

[0001] This invention relates to a hydraulic control system for aircraft nose wheel steering, and more particularly to a hydraulic control system for aircraft nose wheel steering capable of precise adjustment of sway damping. Background Technology

[0002] The aircraft nose wheel steering hydraulic control system is a critical component of aircraft avionics, playing a vital role in takeoff, landing, and ground maneuvering. This system operates in two modes: active steering control and yaw reduction. During takeoff or ground maneuvering, it controls the nose wheel deflection to complete the turn, functioning as active steering. When the wheels are subjected to road surface forces that react to the steering actuators, the system reduces yaw. Due to the high reliability and adjustable damping of hydraulic drives, most aircraft and large unmanned aerial vehicles (UAVs) utilize hydraulic steering for turning.

[0003] Currently, most steering systems use directional valves piloted by on / off valves or conventional servo valves as the core control components to control the actuators. The main drawbacks of steering systems using directional valves piloted by on / off valves are that the turning angle and speed cannot be precisely controlled, and the front wheels are in a free and uncontrolled state after the system is powered off. Steering systems using conventional servo valves as the core control do not have a circuit locking structure similar to a hydraulic lock in the circuit. During the sway reduction process, the zero bias of the servo valve will cause the damping coefficients of the two load chambers to be inconsistent, which will affect the sway reduction performance.

[0004] Meanwhile, the current front wheel steering hydraulic system uses damping valves with fixed orifices. When reducing sway, it relies on the constant damping coefficient of the fixed orifice. The sway damping cannot be adjusted accurately in real time, and the working conditions that the sway reduction can adapt to are relatively limited.

[0005] The existing patent literature references are as follows: The Xi'an Aircraft Design Institute of the Aviation Industry Corporation of China (AVIC) disclosed a fly-by-wire steering system for preventing runaway aircraft in patent application CN201745747U. The system includes a steering control unit, a steering release switch, a solenoid valve, an electro-hydraulic servo valve, a bypass valve, a return oil compensation valve, a throttle valve, a safety valve, a check valve, and an oil filter. Its key feature is the addition of anti-shake hardware circuitry for the steering release switch, an optocoupler circuit, and a relay circuit within the steering control unit. The aforementioned inventions utilize a fixed throttle structure, which differs from the variable throttle damping adjustable structure of this invention.

[0006] Harbin Aircraft Industry Group Co., Ltd. disclosed an aircraft nose wheel steering system in its patent application CN103523217A, titled "Aircraft Nose Wheel Steering System." In this system, the steering control box is connected to a command sensor, a combined hydraulic valve, and a feedback sensor via cables. One end of the command sensor is bolted to the aircraft cockpit floor, and the other end is hinged to the foot pedal via bolts. The combined hydraulic valve is bolted to the nose landing gear bulkhead. The feedback sensor is mounted on the steering actuator; one end of the feedback sensor is clamped to the actuator housing, and the other end is connected to the actuator piston rod via a clip. The steering actuator is mounted on the aircraft nose landing gear, and the piston rod is hinged to the nose landing gear rotating sleeve via a spherical bearing and bolts. This invention focuses on the system's connection method and installation location, which differs from the structural principle of this invention, which uses a hydraulic lock and an electro-proportional throttle valve as key components.

[0007] Nanjing University of Aeronautics and Astronautics disclosed an electric-driven dual-worm gear aircraft nose wheel steering system in its paper "Electric-Driven Dual-Worm Gear Aircraft Nose Wheel Steering System, CN102923300A". This system comprises a first motor, a first reducer, a first clutch, and a first worm gear housed within a housing fixed to the outer cylinder of a strut. The worm gear and the worm wheel form a transmission pair to achieve motion transmission. This invention, using multi-electric aircraft technology, achieves system integration and component reuse, resulting in fewer parts in the electric-driven nose wheel steering system. Its key feature is that it is entirely electrically driven, unlike the hydraulic drive method used in this invention application. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a hydraulic control system for aircraft nose wheel steering that enables precise adjustment of sway damping. The system comprises a direct-drive servo valve 2, a hydraulic lock 11, an electro-proportional throttle valve 4, a replenishment circuit 9, a safety circuit 10, a back pressure control circuit 12, a filter 1, a valve body, an actuator 7, a displacement sensor 6, and a controller 3.

[0009] The direct-drive servo valve 2 is a three-position four-way flow control servo valve with H-type center position function. The oil circuits of output A and output B of the output chamber of the direct-drive servo valve 2 are respectively connected to the two load chambers of the actuator 7, namely load A5 and load B8. A hydraulic lock 11 is installed between the direct-drive servo valve 2 and the actuator 7 circuit. The hydraulic lock 11 consists of two hydraulically controlled check valves to control the opening and closing of the oil circuit in the output chamber. A safety circuit 10, a replenishment circuit 9, and an electro-proportional throttle valve 4 are arranged between the hydraulic lock 11 and the actuator 7. All three circuits are parallel circuits connected to load A5 and load B8. Two safety valves are arranged end to end between the two load chambers, namely load A5 and load B8, to form the safety circuit 10. The electro-proportional throttle valve 4 is connected to both ends of load chamber A5 and load B8, controlled by a motor and has position feedback to adjust the damping magnitude. A filter 1 is arranged at the oil inlet end of the direct-drive servo valve 2, and a back pressure control circuit 12 is arranged at the oil return end of the direct-drive servo valve 2 to increase the back pressure of the oil return.

[0010] Compared with the prior art, the present invention has the following beneficial effects: The actuator is controlled by a direct-drive servo valve as the core control component. Compared with conventional on / off valve solutions, it has higher control accuracy and stronger resistance to contamination. A hydraulic lock is installed directly between the direct-drive servo valve and the actuator to prevent leakage in the load chamber caused by zero bias of the servo valve, which would otherwise lead to uncontrollable damping coefficients in the two load chambers. The motor-driven throttle valve has a position feedback function, which can adjust the valve opening and the damping coefficient of the system to adapt to different sway reduction conditions. Attached Figure Description

[0011] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a hydraulic schematic diagram of the present invention.

[0012] Explanation of reference numerals in the attached figures: 1. Filter; 2. Direct-drive servo valve; 3. Controller; 4. Electro-proportional throttle valve; 5. Load A; 6. Displacement sensor; 7. Actuator; 8. Load B; 9. Oil replenishment circuit; 10. Safety circuit; 11. Hydraulic lock; 12. Back pressure control circuit.

[0013] Figure 2 This is a schematic diagram of the components of the present invention. Detailed Implementation

[0014] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0015] The present invention provides a hydraulic control system for aircraft nose wheel steering that enables precise adjustment of sway damping. This system can be used for the hydraulic control of nose wheel steering in the landing gear of manned / unmanned aircraft that uses hydraulic power as its energy source.

[0016] like Figure 1 As shown, in the embodiment, the present invention includes: a direct-drive servo valve 2, a hydraulic lock 11, an electro-proportional throttle valve 4, an oil replenishment circuit 9, a safety circuit 10, a back pressure control circuit 12, a filter 1, a valve body, an actuator 7, a displacement sensor 6, and a controller 3.

[0017] like Figure 1 As shown, the oil circuits of the output chambers (output A and output B) of the direct-drive servo valve 2 are respectively connected to the two load chambers (load A5 and load B8) of the actuator 7. A hydraulic lock 11 is installed between the circuits of the direct-drive servo valve 2 and the actuator 7. The hydraulic lock 11 consists of two hydraulically controlled check valves, which can control the on / off state of the oil circuits in the output chambers. The hydraulic lock 11 is arranged on the output chamber of the servo valve to lock and open the oil circuit at the output port of the servo valve, which can prevent uncontrollable damping due to zero deviation of the servo valve.

[0018] like Figure 1 As shown, a hydraulic lock 11 is connected in series in the output chambers (output A and output B). The hydraulic control interface of the A-path of the hydraulic lock 11 is connected to the output chamber B, and the hydraulic control interface of the B-path of the hydraulic lock 11 is connected to the output chamber A.

[0019] like Figure 1 As shown, a safety circuit 10, a replenishment circuit 9, and an electro-proportional throttle valve 4 are arranged between the hydraulic lock 11 and the actuator 7. All three circuits are parallel circuits connected to the loads A5 and B8.

[0020] like Figure 1 As shown, two safety valves are connected end-to-end between the two load chambers (load A5 and load B8), forming a safety circuit 10. Safety circuit 10 consists of two high-pressure relief valves arranged alternately between load A5 and load B8. The inlet of one high-pressure relief valve is connected to load A5, and the return end is connected to load B8. The other safety valve is arranged in the opposite manner.

[0021] like Figure 1 As shown, the oil replenishment circuit 9 consists of two check valves. The outlets of the check valves are connected to loads A5 and B8, respectively, and the inlets of the check valves are connected to the return oil end of the direct-drive servo valve 2. When the pressure in the chambers of loads A5 and B8 is lower than the return oil end pressure of the direct-drive servo valve 2, oil replenishment to the chambers of loads A5 and B8 can be achieved.

[0022] like Figure 1As shown, the electro-proportional throttle valve 4 is connected to both ends of load A5 and load B8, controlled by a motor and with position feedback, which can achieve precise adjustment of the damping magnitude of the two-chamber load.

[0023] like Figure 1 As shown, the system has an oil filter installed at the oil inlet of the direct-drive servo valve 2 and a back pressure control circuit 12 installed at the oil return end of the direct-drive servo valve 2 to increase the back pressure of the oil return.

[0024] The electro-proportional throttle valve 4 is not limited to being driven by a brushless, brushed, or even other types of motors. The motor drive is converted into the movement of the valve core, thereby adjusting the opening of the throttle valve orifice. The form of the throttle valve orifice is not limited to needle valves or spool valves. An angle sensor is installed at one end of the motor, and the valve core displacement value is fed back to the controller 3 through the angle sensor to realize the detection and control of the valve core position.

[0025] like Figure 1 As shown, a filter 1 is arranged at the inlet end of the direct-drive servo valve 2, and the external oil first passes through the filter 1 before entering the supply end of the direct-drive servo valve 2. A back pressure control circuit 12 is arranged at the return end of the direct-drive servo valve 2 to raise the return oil pressure of the servo valve. The back pressure control circuit 12 consists of an accumulator and a low-pressure relief valve connected in parallel. The pressure regulating end (front end) of the back pressure control circuit 12 is connected to the return oil of the direct-drive servo valve 2, and the rear end is connected to the return oil of the external pipeline of the turning hydraulic control system.

[0026] The direct-drive servo valve 2 is a three-position four-way flow control servo valve with H-type center position function.

[0027] like Figure 2 As shown, filter 1, direct-drive servo valve 2, hydraulic lock 11, safety circuit 10, oil replenishment circuit 9, electro-proportional throttle valve 4, and back pressure control circuit 12 are all integrated on one valve body. These functional components are collectively referred to as a turning combination valve.

[0028] like Figure 2 As shown, displacement sensor 6 and actuator 7 are integrated into one unit, forming the execution part of the system. Displacement sensor 6 is connected in parallel to actuator 7. The body of displacement sensor 6 is fixed to the cylinder of actuator 7, and the connecting rod is fixed to the piston rod of actuator 7. Displacement sensor 6 is used to detect the displacement of piston rod of actuator 7 and feed the displacement back to controller 3, forming a closed-loop control of the position of actuator 7.

[0029] Controller 3 has an H-bridge drive output function, providing positive and negative current outputs to the direct-drive servo valve 2 to control the forward and reverse flow outputs of the direct-drive servo valve 2. The output current of controller 3 controls the motor movement to adjust the valve opening of the throttle valve, thereby adjusting the damping of the turning control system.

[0030] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A hydraulic control system for aircraft nose wheel steering capable of precise adjustment of yaw reduction damping, characterized in that, It includes a direct-drive servo valve (2), a hydraulic lock (11), an electro-proportional throttle valve (4), a replenishment circuit (9), a safety circuit (10), a back pressure control circuit (12), a filter (1), a valve body, an actuator (7), a displacement sensor (6), and a controller (3). The direct-drive servo valve (2) is a three-position four-way flow control servo valve with H-type center position function. The oil circuits of output A and output B of the output chamber of the direct-drive servo valve (2) are respectively connected to the two load chambers of the actuator (7), namely load A (5) and load B (8). A hydraulic lock (11) is installed in the middle of the circuit of the direct-drive servo valve (2) and the actuator (7). The hydraulic lock (11) consists of two hydraulic control check valves to realize the control of the oil circuit of the output chamber. A safety circuit (10), a replenishment circuit (9), and an electro-proportional throttle valve (4) are arranged between the hydraulic lock (11) and the actuator (7). All three circuits are parallel circuits connected to load A (5) and load B (8). Two safety valves are arranged end to end between the two load chambers, namely load A (5) and load B (8), to form a safety circuit (10). The electro-proportional throttle valve (4) is connected to both ends of load chamber A and load B (8), controlled by a motor and has position feedback to adjust the damping magnitude. A filter (1) is arranged at the oil inlet end of the direct-drive servo valve (2), and a back pressure control circuit (12) is arranged at the oil return end of the direct-drive servo valve (2) to increase the back pressure of the oil return.

2. The aircraft nose wheel steering hydraulic control system capable of precise adjustment of sway damping according to claim 1, characterized in that, The safety circuit (10) consists of two high-pressure relief valves arranged alternately between load A (5) and load B (8). The oil inlet of one high-pressure relief valve is connected to the chamber of load A (5), and the oil return end is connected to the chamber of load B (8). The other safety valve is arranged in the opposite direction.

3. The aircraft nose wheel steering hydraulic control system capable of precise adjustment of sway damping according to claim 1, characterized in that, The hydraulic lock (11) is arranged on the output chamber of the servo valve to lock and open the oil circuit of the servo valve output port, so as to avoid the uncontrollable damping caused by the zero bias of the servo valve.

4. The aircraft nose wheel steering hydraulic control system capable of precise adjustment of sway damping according to claim 1, characterized in that, The oil replenishment circuit (9) consists of two check valves. The outlet of the check valve is connected to load A (5) and load B (8) respectively, and the inlet of the check valve is connected to the return oil end of the direct drive servo valve (2).

5. The aircraft nose wheel steering hydraulic control system capable of precise adjustment of yaw reduction damping according to claim 1, characterized in that, The electro-proportional throttle valve (4) uses a brushless motor or a brushed motor. The motor drive is converted into the movement of the valve core, thereby adjusting the opening of the throttle valve port. An angle sensor is arranged at one end of the motor. The valve core displacement value is fed back to the controller (3) through the angle sensor to realize the detection and control of the valve core position.

6. According to claim 1, a hydraulic control system for aircraft nose wheel turning that can achieve precise adjustment of damping is provided, wherein a back pressure control circuit (12) is arranged at the return oil end of the direct drive servo valve (2) to raise the return oil pressure of the servo valve. The back pressure control circuit (12) is composed of an accumulator and a low pressure relief valve connected in parallel. The pressure regulating end of the back pressure control circuit (12) is connected to the return oil of the direct drive servo valve (2) at the front end and connected to the return oil of the external pipeline of the turning hydraulic control system at the rear end.

7. According to claim 1, the aircraft nose wheel turning hydraulic control system that can realize precise adjustment of sway damping, the filter (1), direct drive servo valve (2), hydraulic lock (11), safety circuit (10), oil replenishment circuit (9), electro-proportional throttle valve (4), and back pressure control circuit (12) are all integrated on a valve body and are collectively referred to as the turning combination valve.

8. According to claim 1, the aircraft nose wheel turning hydraulic control system that can realize precise adjustment of damping is provided, the displacement sensor (6) and the actuator (7) are integrated into one unit as the execution part of the system. The displacement sensor (6) is connected in parallel on the actuator (7). The body of the displacement sensor (6) is fixed on the cylinder of the actuator (7), and the pull rod is fixed on the piston rod of the actuator (7). The displacement sensor (6) is used to detect the displacement of the piston rod of the actuator (7) and feed the displacement back to the controller (3) to form a closed-loop control of the position of the actuator (7).

9. According to claim 1, the aircraft nose wheel turning hydraulic control system that can realize precise adjustment of damping is provided, the controller (3) has H-bridge drive output function, provides positive and negative current output to the direct drive servo valve (2) to control the positive and negative flow output of the direct drive servo valve (2); the controller (3) outputs current to control the motor movement to adjust the valve opening of the throttle valve and realize the adjustment of the damping of the turning control system.

Images