Universal test device and method for centering torque of undercarriage

Abstract

The invention discloses an undercarriage centering torque general test device and method. The undercarriage centering torque general test device comprises a rack structure, a motion decoupling mechanism, a torque conversion mechanism and a lifting mechanism. The motion decoupling mechanism converts downward displacement, rotation and coupling motion of the undercarriage strut into independent rotation and up-down displacement motion, and transmits the independent rotation and up-down displacement motion to the torque conversion mechanism to complete test measurement; the torque conversion mechanism transmits and converts torsional motion into motion in the horizontal direction through a driving gear, a driven gear, a pneumatic jaw clutch and a cam, then the motion acts on a straight spring, and force is transmitted to a pressure sensor through compression of the straight spring to complete test measurement of centering torque. According to the invention, the problems of complex device structure, poor universality and frequent spring replacement in the centering torque test are solved, the universality measurement of the centering torque of different aircraft landing gears can be realized by setting different spring pre-tightening amounts, and the device has important significance for delivery inspection of landing gears and safe take-off and landing of aircrafts.

Description

Technical Field

[0001] The present invention belongs to the technical field of aircraft performance test devices, specifically relates to a universal test device for the centering torque of landing gears, and also relates to a universal test method for the centering torque of landing gears. Background Art

[0002] With the upgrade of China's aviation industry and continuous technological breakthroughs, the requirements for the working performance and stability of landing gears are getting higher and higher. Precise control of the retraction / extension, turning, centering and other actions of landing gears has become the key to ensuring flight safety. The centering test of landing gears is an important test to detect whether the centering action, centering angle and centering torque of landing gears meet the requirements. A reasonable centering torque is a key parameter to ensure that the landing gear can return to the cabin during takeoff. If this parameter deviates from the design threshold, it will lead to faults such as the deviation of the retraction / extension mechanism trajectory and the jamming of the cabin door, seriously threatening flight safety.

[0003] At present, relevant solution devices have been initially developed for measuring the torque generated when the aircraft landing gear returns to the center. For example, the Chinese invention patent "Dynamic Measuring Device and Method for the Centering Moment of the Front Landing Gear of an Aircraft" with the patent application number 202410625530.9. The torque transmission system of this device is designed complexly, the torsion spring is difficult to disassemble and assemble, and the maintenance is inconvenient. Moreover, landing gears of different specifications need torsion springs with different stiffnesses for matching, resulting in poor versatility. For example, the Chinese invention patent "A Torsion Device for the Centering Test of the Front Landing Gear of an Aircraft" with the patent application number 202411990101.8. This device focuses on the torsion problem when the landing gear returns to the center. Compared with the traditional manual rotation of the landing gear to complete torsion, this device can automate this process and has higher control precision, but it does not detect the torque generated when the landing gear returns to the center and lacks the analysis of the centering performance of the landing gear. For example, the Chinese invention patent "Test Device for the Centering Performance of the Front Landing Gear of a Fighter Jet" with the patent application number 201911038599.7. This device is only a structure for the centering performance experiment of the landing gear, measuring the angular position of the piston rod of the shock strut after centering, and cannot measure the torque generated when the piston rod of the shock strut returns to the center, lacking an intuitive analysis of the torque generated when the landing gear returns to the center. Another example is the Chinese invention patent "Automatic Centering Test Device for Landing Gears" with the patent application number 201910588163.9. This device is a device for the automatic centering experiment of the landing gear, realizing the function of precisely controlling the rotation angle of the piston rod of the shock strut, but it does not reflect the dynamic change process of the torque when the piston rod of the shock strut returns to the center and cannot draw the torque change curve during the centering process. Summary of the Invention

[0004] The purpose of the present invention is to provide a universal test device and test method for the centering torque of landing gears, which solves the problems of complex device structure and poor versatility caused by frequent spring replacement in the existing centering torque test of landing gears.

[0005] The object of the present invention also lies in providing a general test method for the centering torque of an aircraft landing gear.

[0006] The first technical solution adopted by the present invention is: a general test device for the centering torque of a landing gear, including a frame structure, a motion decoupling mechanism, a torque conversion mechanism, and a lifting mechanism. The frame structure separates each of the structures therein from the outside; the lower part of the motion decoupling mechanism is connected to the torque conversion mechanism, and the torque conversion mechanism is used to transmit the force generated during the centering of the landing gear and measure the torque generated during the centering of the landing gear; the lifting mechanism is installed on the bottom plate of the frame structure and is used to compress the landing gear shock strut.

[0007] The present invention is further characterized in that The frame structure is welded by steel plates, with a reasonable and compact overall base layout, a simple and beautiful appearance, a firm and reliable structure, sufficient space reserved for other mechanisms without interference, separating each of the structures therein from the outside and providing protection for each mechanism to ensure the smooth progress of the experiment.

[0008] The frame structure consists of an upper cover plate of the box body, a middle plate of the box body, and a lower plate of the box body. The middle plate of the box body is used to install the torque conversion mechanism, the lower plate of the box body is installed below the middle plate of the box body to support the overall structure, and the upper cover plate of the box body is installed above the middle plate of the box body to seal the top of the overall structure.

[0009] The motion decoupling mechanism mainly consists of an upper part of a wheel axle fixing seat, a guide rod, a sliding guide sleeve, etc.; the lower part of the wheel axle fixing seat is installed above the connecting plate and is used to fix the landing gear wheel axle. The upper part of the wheel axle fixing seat is installed on the lower part of the wheel axle fixing seat to prevent it from disengaging from the landing gear wheel axle when the motion decoupling mechanism drops, which affects torque measurement. The upper part of the guide rod is installed on the connecting plate, and the lower part is fixed by a guide rod fixing plate to avoid shaking during operation. The guide rod passes downward through the sliding guide sleeve mounting plate, and a sliding guide sleeve is sleeved on the upper part of the guide rod. The sliding guide sleeve is located above the sliding guide sleeve mounting plate, and the sliding guide sleeve mounting plate is connected to the turntable bearing a of the torque conversion mechanism, enabling the entire motion decoupling mechanism to rotate freely.

[0010] The torque conversion mechanism includes a gear shaft, a pneumatic jaw clutch, and a pneumatic jaw clutch main shaft; the turntable bearing a is installed on the middle plate of the box body. An active gear is installed on the outer ring of the turntable bearing a. A driven gear meshing with the active gear is arranged on one side of the active gear. The driven gear is installed on the gear shaft and axially positioned by a locking retaining ring and a sleeve. A deep groove ball bearing is installed on the upper part of the gear shaft and fixed on the upper cover plate of the box body. A deep groove ball bearing is installed in the middle of the gear shaft and fixed on the middle plate of the box body to ensure the fixation and rotation of the gear shaft; the pneumatic jaw clutch is connected to the lower part of the gear shaft. A pneumatic jaw clutch flange is connected to the lower part of the pneumatic jaw clutch by screws. A deep groove ball bearing is fixed inside the pneumatic jaw clutch flange, and its inner ring is fixed at the bottom end of the gear shaft. The lower end of the pneumatic jaw clutch flange is connected to the pneumatic jaw clutch main shaft. A deep groove ball bearing is fixed at the upper end of the pneumatic jaw clutch main shaft and installed on the middle plate of the box body. A cam is connected to the middle of the pneumatic jaw clutch main shaft and axially positioned by a sleeve. A deep groove ball bearing is fixed at the lower part of the pneumatic jaw clutch main shaft and installed on the lower plate of the box body to stabilize the overall structure.

[0011] A chute base is installed on the lower plate of the box body. The chute base serves as the support of the torque conversion mechanism, used to place a straight spring and a pressure sensor and provide a guiding function. The straight spring and the pressure sensor are sealed with a chute cover above. A straight spring seal cover is arranged at the front end of the straight spring. When the system works, the cam will squeeze the straight spring seal cover to compress the straight spring and transfer the force to the pressure sensor. The other end of the pressure sensor is connected to a screw jack. The screw jack is connected to the screw through a deep groove ball bearing. The screw is connected to the middle plate of the box body through a screw sleeve. Threads are machined inside the screw sleeve; one end of the screw located outside the box body is connected to a rotary handwheel, and the rotary handwheel can apply a pre-tightening force to the pressure sensor.

[0012] Through the cooperation of the active gear and the driven gear on the turntable bearing a, the angle of centering is amplified, and finally the force is applied to the straight spring through the pneumatic jaw clutch. The transmission gear is fixed on the base so that it cannot move up and down but can only rotate. The connecting plate is connected to the wheel axle of the landing gear to transmit the rotation. The lower end of the connecting plate is connected to the guide rod, and the lower part is connected to the sliding guide sleeve so that the guide rod can move up and down freely and transmit the rotational movement to the gear. The inner ring of the turntable bearing is fixed on the base, and a gear is installed on the outer ring. At the same time, the sliding guide sleeve is also connected and fixed to the upper end of the turntable bearing. During the centering test, the torque during the centering process is transmitted to the driven gear on one side through the gear on the turntable bearing. While realizing torque transmission, the up-and-down coupling movement of the bare rod is eliminated.

[0013] The pneumatic jaw clutch of the gear transmits the motion through the transmission gear, and finally acts on the straight spring through the driving gear and the pneumatic jaw clutch. During the centering test, the transmission gear is connected to the 4 guide rods of the motion decoupling mechanism through the bushing. The gear on the turntable bearing receives the centering torque obtained by the motion decoupling mechanism from the landing gear shock strut, and transfers the centering torque to the rotating shaft on the side through its gear. A pneumatic jaw clutch is installed on the rotating shaft, and a cam is installed at its lower part. The force is transmitted to the straight spring through the pneumatic jaw clutch to compress it, and finally acts on the pressure sensor. The general test data of the centering torque of the test piece is collected and recorded and analyzed through the pressure sensor. The pressure sensor is used for the real-time measurement of the centering torque during the centering process of the landing gear; the straight spring is used to provide the follow-up load during the centering process and is a key component of the torque measurement mechanism. A cam is installed at the lower part of the pneumatic jaw clutch. When the centering torque drives the cam to rotate through the transmission mechanism, the cam will compress the straight spring. At this time, the straight spring deforms and its acting force directly acts on the pressure sensor. With the continuous movement of centering, the force acting on the pressure sensor is continuous, and the centering torque curve during the entire centering process can be measured. The function of the pneumatic jaw clutch is to energize it through the control system after the test is completed, so that the reaction force from the straight spring can be released without affecting the normal operation of other mechanisms.

[0014] The lifting mechanism includes a turntable bearing b, a piston rod and a hydraulic cylinder; the turntable bearing b is installed at the top of the piston rod and can rotate simultaneously with the connecting plate during the centering test of the landing gear. The piston rod can push the connecting plate to compress the shock strut of the landing gear.

[0015] The second technical solution adopted by the present invention is: a general test method for the centering torque of an aircraft landing gear, and the specific operation steps are as follows: Step 1: The staff first place the general test device for the centering torque of the landing gear under the landing gear and adjust the axis of the hydraulic cylinder to coincide with the axis of the landing gear shock strut. At this time, the frame structure supports the entire device to ensure the stability of the overall structure; Step 2: Before the measurement starts, the pneumatic jaw clutch is in the off state, so that the lower part of the torque conversion mechanism will not rotate. Drive the piston rod to push the connecting plate, press the lower part of the axle fixing seat against the landing gear axle, connect the upper part of the axle fixing seat with the lower part of the axle fixing seat, the piston rod starts to compress the landing gear shock strut, and at the same time control the landing gear to start turning; Step 3: Ensure that the pneumatic jaw clutch is in the closed state at the start of the measurement. At this time, the hydraulic cylinder performs a quick retraction action. The four guide rods at the lower part of the connecting plate are connected to the driving gear through sliding guide sleeves and drive it to rotate, and transmit the motion to the gear shaft through the driven gear, while achieving the amplification and acceleration of the rotation angle. When the landing gear returns to the center, the gear-driven cam compression will squeeze the straight spring cover, and the straight spring cover compresses the straight spring, transmitting the force to the pressure sensor; when the measurement of the return-to-center torque is completed, the straight spring is in a compressed state at this time. By controlling the opening and closing of the pneumatic jaw clutch, the straight spring is released, and then the straight spring returns to the initial state; Step 4: The return-to-center torque on the shock strut finally acts on the pressure sensor, and the measurement and control system records the data of the pressure sensor in real time, and the return-to-center torque during the return-to-center process can be obtained, completing the performance test and recording of the product to be tested.

[0016] Step 5: At the end of the test, the lifting mechanism rises to the lower part of the connecting plate of the motion decoupling mechanism, removes the upper part of the wheel axle fixing seat to separate the wheel axle from the connecting plate of the decoupling mechanism, and then the lifting mechanism returns to its original position.

[0017] The beneficial effects of the present invention are as follows: The frame structure of the present invention provides the support and fixation for the entire test device, ensuring the stability of the device during the test and avoiding measurement errors caused by vibration or displacement; the motion decoupling mechanism ensures that the torsional motion is independently transmitted to the torque conversion mechanism, avoiding the mutual coupling of motions; the torque conversion mechanism converts the torsional motion into a linear motion in the horizontal direction, and completes the torque measurement through the straight spring and the pressure sensor. The landing gear return-to-center torque test device of the present invention has a simple structure, does not require spring replacement, can be applicable to the measurement and test of the return-to-center torque of different specifications of aircraft landing gears, has good versatility, can provide technical support for the performance test of aircraft landing gears, and is of great significance for the ex-factory inspection of landing gears and the safe takeoff and landing of aircraft. Description of the Drawings

[0018] Figure 1 It is the overall structure diagram of the device of the present invention; Figure 2 It is the schematic diagram of the frame structure in the present invention; Figure 3 It is the schematic diagram of the motion decoupling mechanism in the present invention; Figure 4 It is the schematic diagram of the torque conversion mechanism in the present invention; Figure 5 It is the schematic diagram of the lifting mechanism in the present invention.

[0019] In the figure, 1. frame structure, 2. motion decoupling mechanism, 3. torque conversion mechanism, 4. lifting mechanism, 5. upper cover plate of the box body, 6. middle plate of the box body, 7. lower plate of the box body, 8. upper part of the wheel axle fixing seat, 9. lower part of the wheel axle fixing seat, 10. connecting plate, 11. guide rod, 12. sliding guide sleeve, 13. sliding guide sleeve mounting plate, 14. guide rod fixing plate, 15. turntable bearing a, 16. driving gear, 17. bearing fixing plate, 18. gear shaft, 19. locking retaining ring, 20. driven gear, 21. pneumatic jaw clutch, 22. pneumatic jaw clutch flange, 23. pneumatic jaw clutch main shaft, 24. cam, 25. sleeve, 26. straight spring cover, 27. chute base, 28. straight spring, 29. chute cover, 30. pressure sensor, 31. screw top piece, 32. screw sleeve, 33. screw, 34. rotating handwheel, 35. turntable bearing b, 36. piston rod, 37. hydraulic cylinder. Specific embodiments

[0020] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0021] Embodiment 1 As Figure 1 shown, the general test device for the centering torque of the landing gear in this embodiment includes a frame structure 1, a motion decoupling mechanism 2, a torque conversion mechanism 3, and a lifting mechanism 4. The frame structure 1 separates each structure therein from the outside; the lower part of the motion decoupling mechanism 2 is connected to the torque conversion mechanism 3, and the torque conversion mechanism 3 is used to transmit the force generated during the centering of the landing gear and measure the torque generated during the centering of the landing gear; the lifting mechanism 4 is installed on the bottom plate of the frame structure and is used to compress the landing gear shock strut.

[0022] As Figure 2 shown, the frame structure 1 is composed of an upper cover plate 5 of the box body, a middle plate 6 of the box body, and a lower plate 7 of the box body. The middle plate 6 of the box body is used to install the torque conversion mechanism 3. The lower plate 7 of the box body is installed below the middle plate 6 of the box body to support the overall structure. The upper cover plate 5 of the box body is installed on the upper part of the middle plate 6 of the box body to seal the top of the overall structure.

[0023] Embodiment 2 On the basis of Embodiment 1, as Figure 3As shown, the motion decoupling mechanism 2 mainly consists of the upper part 8 of the wheel axle fixing seat, the guide rod 11, the sliding guide sleeve 12, etc.; the lower part 9 of the wheel axle fixing seat is installed above the connecting plate 10 for fixing the landing gear wheel axle. The upper part 8 of the wheel axle fixing seat is installed on the lower part 9 of the wheel axle fixing seat to prevent it from disengaging from the landing gear wheel axle when the motion decoupling mechanism 2 falls, which may affect the torque measurement. The upper part of the guide rod 11 is installed on the connecting plate 10, and the lower part is fixed by the guide rod fixing plate 14 to avoid shaking during operation. The guide rod 11 passes downward through the sliding guide sleeve mounting plate 13. The upper part of the guide rod 11 is sleeved with the sliding guide sleeve 12. The sliding guide sleeve 12 is located above the sliding guide sleeve mounting plate 13. The sliding guide sleeve mounting plate 13 is connected to the turntable bearing a15 of the torque conversion mechanism 3, enabling the entire motion decoupling mechanism 2 to rotate freely.

[0024] Embodiment 3 On the basis of Embodiment 2, as Figure 4 shown, the torque conversion mechanism 3 includes a gear shaft 19, a pneumatic jaw clutch 21, and a pneumatic jaw clutch main shaft 24; the turntable bearing a15 is installed on the middle plate 6 of the box body. An active gear 16 is installed on the outer ring of the turntable bearing a15. A driven gear 20 meshing with the active gear 16 is arranged on one side of the active gear 16. The driven gear 20 is installed on the gear shaft 19 and axially positioned with a locking retaining ring 19 and a sleeve. A deep groove ball bearing is installed on the upper part of the gear shaft 19 and fixed on the upper cover plate 5 of the box body. A deep groove ball bearing is installed in the middle of the gear shaft 19 and fixed on the middle plate 6 of the box body to ensure the fixation and rotation of the gear shaft 19. The pneumatic jaw clutch 21 is connected to the lower part of the gear shaft 19. The lower part of the pneumatic jaw clutch 21 is connected with a pneumatic jaw clutch flange 22 by screws. A deep groove ball bearing is fixed inside the pneumatic jaw clutch flange 22, and its inner ring is fixed at the bottom end of the gear shaft 19. The lower end of the pneumatic jaw clutch flange 22 is connected to the pneumatic jaw clutch main shaft 23. The upper end of the pneumatic jaw clutch main shaft 23 is fixed with a deep groove ball bearing and installed on the middle plate 6 of the box body. A cam 24 is connected to the middle of the pneumatic jaw clutch main shaft 23. The cam 24 is axially positioned by a sleeve 25. The lower part of the pneumatic jaw clutch main shaft 23 is fixed with a deep groove ball bearing and installed on the lower plate 7 of the box body to stabilize the overall structure.

[0025] A chute base 27 is installed on the lower part of the box body 7. The chute base 27 serves as the support of the torque conversion mechanism, which is used to place the straight spring 28 and the pressure sensor 30 and provide a guiding function. The upper part of the straight spring 28 and the pressure sensor 30 is sealed with a chute cover 29. A straight spring cover 26 is provided at the front end of the straight spring 28. When the system works, the cam 24 will squeeze the straight spring cover 26 to compress the straight spring 28, and transmit the force to the pressure sensor 30. The other end of the pressure sensor 30 is connected with a lead screw top part 31. The lead screw top part 31 is connected to the lead screw 33 through a deep groove ball bearing. The lead screw 33 is connected to the middle part of the box body 6 through a lead screw sleeve 32, and the inside of the lead screw sleeve 32 is machined with threads; One end of the lead screw 33 located outside the box body is connected with a rotary handwheel 34, and the rotary handwheel 34 can apply a pre-tightening force to the pressure sensor 30.

[0026] Embodiment 4 On the basis of Embodiment 3, as Figure 5 shown, the lifting mechanism 4 includes a slewing bearing b35, a piston rod 36 and a hydraulic cylinder 37; The slewing bearing b35 is installed at the top of the piston rod 36 and can rotate simultaneously with the connecting plate 10 during the centering test of the landing gear. The piston rod 36 can push the connecting plate 10 to compress the shock strut of the landing gear.

[0027] Embodiment 5 In the general test method for the centering torque of the landing gear in the present invention, the motion decoupling mechanism 2 displaces and rotates the landing gear strut downward, converts the coupled motion into independent rotational and vertical displacement motions, and transmits them to the torque conversion mechanism 3 to complete the test measurement; The torque conversion mechanism 3 transmits and converts the torsional motion into a horizontal motion through the driving gear, driven gear, pneumatic jaw clutch and cam, and then acts on the straight spring. The force is transmitted to the pressure sensor through the compression of the straight spring to complete the test measurement of the centering torque.

[0028] Embodiment 6 The general test method for the centering torque of the landing gear of the present invention has the following specific operation process steps: The first step: The staff first place the general test device for the centering torque of the landing gear under the landing gear and adjust the axis of the hydraulic cylinder 37 to coincide with the axis of the landing gear shock strut. At this time, the frame structure 1 supports the whole device to ensure the stability of the overall structure; The second step: Before the measurement starts, the pneumatic jaw clutch 21 is in the disengaged state, so that the lower part of the torque conversion mechanism 3 does not rotate. Drive the piston rod 36 to push the connecting plate 10, press the lower part 9 of the wheel axle fixing seat against the landing gear wheel axle, connect the upper part 8 of the wheel axle fixing seat with the lower part 9 of the wheel axle fixing seat, the piston rod 36 starts to compress the landing gear shock strut, and at the same time control the landing gear to start turning.

[0029] Step 3: Ensure that the pneumatic jaw clutch is in the closed state at the start of measurement. At this time, the hydraulic cylinder 37 performs a fast retraction action. The four guide rods 11 at the lower part of the connecting plate 10 are connected to the driving gear 16 through the sliding guide sleeves 12 and drive it to rotate, and the movement is transmitted to the gear shaft 18 through the driven gear 20, while achieving the amplification and acceleration of the rotation angle. When the landing gear returns to the center, the gear drives the cam 24 to compress and squeeze the straight spring cover 26, and the straight spring cover 26 compresses the straight spring 28, transmitting the force to the pressure sensor 30. When the measurement of the return-to-center torque is completed, the straight spring is in the compressed state at this time. By controlling the opening and closing of the pneumatic jaw clutch, the straight spring is released, and then the straight spring is in the initial state.

[0030] Step 4: The return-to-center torque on the shock strut finally acts on the pressure sensor. The measurement and control system records the data of the pressure sensor in real time, and the return-to-center torque during the return-to-center process can be obtained, completing the performance test and recording of the product to be tested.

[0031] Step 5: At the end of the test, the lifting mechanism 4 rises to the lower part of the connecting plate 10 of the motion decoupling mechanism 2, removes the upper part 8 of the wheel axle fixing seat to separate the wheel axle from the connecting plate 10 of the decoupling mechanism 2, and then the lifting mechanism 4 is reset.

Claims

1. Universal test device for landing gear return torque, characterized in that: The invention comprises a frame structure (1), a motion decoupling mechanism (2), a torque conversion mechanism (3), and a lifting mechanism (4), wherein the frame structure (1) separates the other structures from the outside; the lower part of the motion decoupling mechanism (2) is connected to a torque conversion mechanism (3), and the torque conversion mechanism (3) is used to transmit the force generated when the landing gear returns to the center and measure the torque generated when the landing gear returns to the center; the lifting mechanism (4) is installed on the bottom plate of the frame structure and is used to compress the landing gear buffer strut.

2. The universal testing device for landing gear centering torque according to claim 1, characterized in that: The frame structure (1) is a box structure comprising an upper box cover plate (5), a middle box plate (6) and a lower box plate (7); the middle box plate (6) is used to install the torque conversion mechanism (3); the lower box plate (7) is installed at the bottom of the middle box plate (6) to support the overall structure; the upper box cover plate (5) is installed on the upper part of the middle box plate (6).

3. The landing gear return torque universal test device according to claim 1, characterized in that: The motion decoupling mechanism (2) comprises a connecting plate (10), a lower part of a wheel axle fixing seat (9) is fixed above the connecting plate (10), an upper part of a wheel axle fixing seat (8) is connected to the lower part of the wheel axle fixing seat (9), a plurality of guide rods (11) are fixedly connected below the connecting plate (10), the lower parts of the guide rods (11) are fixedly connected to a guide rod fixing plate (14); a sliding guide sleeve (12) is connected to the middle part of the guide rod (11); the sliding guide sleeve (12) is mounted on a sliding guide sleeve mounting plate (13); the sliding guide sleeve mounting plate (13) is connected to the upper part of a turntable bearing a (15) of the torque conversion mechanism (3) so that the entire motion decoupling mechanism (2) can rotate freely.

4. The universal testing device for landing gear centering torque according to claim 3, characterized in that: The upper part (8) of the wheel axle fixing seat and the lower part (9) of the wheel axle fixing seat are used to fix the landing gear wheel axle to prevent the motion decoupling mechanism (2) from being disengaged from the landing gear wheel axle when it falls, thereby affecting torque measurement.

5. The universal testing device for landing gear centering torque according to claim 3, characterized in that: The torque conversion mechanism (3) comprises a gear shaft (19), a pneumatic tooth clutch (21) and a pneumatic tooth clutch main shaft (23); the turntable bearing a (15) is mounted on the middle plate (6) of the housing; a driving gear (16) is mounted on the outer ring of the turntable bearing a (15); a driven gear (20) meshing with the driving gear (16) is arranged on one side of the driving gear (16); the driven gear (20) is mounted on the gear shaft (19) and axially positioned by a locking retaining ring (19) and a sleeve; a deep groove ball bearing is mounted on the upper part of the gear shaft (19); the deep groove ball bearing is fixed on the upper cover plate (5) of the housing; a deep groove ball bearing is mounted on the middle part of the gear shaft (19) and fixed on the middle plate (6) of the housing to ensure the fixation and rotation of the gear shaft (19); the pneumatic tooth clutch (21) is mounted on the outer ring of the turntable bearing a (15); a driving gear (16) is mounted on the outer ring of the turntable bearing a (15); a driven gear (20) meshing with the driving gear (16) is arranged on one side of the driving gear (16); the driven gear (20) is mounted on the gear shaft (19) and axially positioned by a locking retaining ring (19) and a sleeve; a deep groove ball bearing is mounted on the upper part of the gear shaft (19); the deep groove ball bearing is fixed on the upper cover plate (5) of the housing; a deep groove ball bearing is mounted on the middle part of the gear shaft (19) and fixed on the middle plate (6) of the housing to ensure the fixation and rotation of the gear shaft (19); The pneumatic tooth clutch (21) is connected to the lower part of the gear shaft (19). The lower part of the pneumatic tooth clutch (21) is connected to the pneumatic tooth clutch flange (22) by screws. A deep groove ball bearing is fixed inside the pneumatic tooth clutch flange (22). The inner ring of the flange is fixed to the bottom end of the gear shaft (19). The lower end of the pneumatic tooth clutch flange (22) is connected to the pneumatic tooth clutch main shaft (23). The upper end of the pneumatic tooth clutch main shaft (23) is fixed with a deep groove ball bearing and is installed on the middle plate (6) of the box body. The middle part of the pneumatic tooth clutch main shaft (23) is connected to a cam (24). The cam (24) is axially positioned by a sleeve (25). The lower part of the pneumatic tooth clutch main shaft (23) is installed on the lower plate (7) of the box body through a deep groove ball bearing to stabilize the overall structure.

6. The universal testing device for landing gear centering torque according to claim 5, characterized in that: A slide groove base (27) is installed on the lower plate (7) of the box body. The slide groove base (27) serves as a support for the torque conversion mechanism and is used to place a straight spring (28) and a pressure sensor (30) and provide a guiding function. The straight spring (28) and the pressure sensor (30) are sealed with a slide groove cover (29). A straight spring cover (26) is provided at the front end of the straight spring (28). When the system is working, the cam (24) squeezes the straight spring cover (26) to compress the straight spring (28). , the force is transmitted to the pressure sensor (30), the other end of the pressure sensor (30) is connected to a lead screw top piece (31), the lead screw top piece (31) is connected to a lead screw (33) via a deep groove ball bearing, the lead screw (33) is connected to the middle plate (6) of the box body via a lead screw sleeve (32), and the interior of the lead screw sleeve (32) is processed with threads; one end of the lead screw (33) located outside the box body is connected to a rotating hand wheel (34), and the rotating hand wheel (34) can apply a pre-tightening force to the pressure sensor (30).

7. The universal testing device for landing gear centering torque according to claim 6, characterized in that: The lifting mechanism (4) comprises a turntable bearing b (35), a piston rod (36) and a hydraulic cylinder (37); the turntable bearing b (35) is mounted on the top of the piston rod (36) and can rotate simultaneously with the connecting plate (10) during a landing gear return test; the piston rod (36) can push the connecting plate (10) to compress the buffer strut of the landing gear.

8. The universal test method for landing gear return torque is characterized by: The motion decoupling mechanism (2) displaces and rotates the landing gear strut downward, converts the coupled motion into independent rotation and up and down displacement motion, and transmits it to the torque conversion mechanism (3) to complete the test measurement; the torque conversion mechanism (3) transmits and converts the torsional motion into horizontal motion through the driving gear, the driven gear, the pneumatic tooth clutch, and the cam, and then acts on the straight spring, and transmits the force to the pressure sensor through the compression of the straight spring to complete the test measurement of the return torque.

9. The universal test method for landing gear return torque according to claim 8, characterized in that: The specific steps are as follows: Step 1: The staff first places the landing gear return torque universal test device under the landing gear and adjusts the axis of the hydraulic cylinder (37) to coincide with the axis of the landing gear buffer strut. At this time, the frame structure (1) supports the entire device to ensure the stability of the overall structure; Step 2: Before the measurement starts, the pneumatic tooth clutch (21) is in a disconnected state, so that the lower part of the torque conversion mechanism (3) does not rotate, and the piston rod (36) is driven to push the connecting plate (10), so that the lower part of the axle fixing seat (9) is pressed against the landing gear axle, and the upper part of the axle fixing seat (8) is connected to the lower part of the axle fixing seat (9), and the piston rod (36) starts to compress the landing gear buffer strut, and at the same time controls the landing gear to start turning; Step 3: At the beginning of the measurement, ensure that the pneumatic tooth clutch is in a closed state. At this time, the hydraulic cylinder (37) performs a quick withdrawal action, and the guide rod (11) at the lower part of the connecting plate (10) is connected to the driving gear (16) through the sliding guide sleeve (12) and drives it to rotate, and transmits the movement to the gear shaft (18) through the driven gear (20), while realizing the amplification and acceleration of the rotation angle; when the landing gear is returned to the center, the gear drives the cam (24) to compress and squeeze the straight spring cover (26), and the straight spring cover (26) compresses the straight spring (28) and transmits the force to the pressure sensor (30); when the return torque measurement is completed, the straight spring is in a compressed state, and the straight spring is released by controlling the opening and closing of the pneumatic tooth clutch, and then the straight spring is in the initial state; Step 4: The return torque on the buffer support finally acts on the pressure sensor. The measurement and control system records the data of the pressure sensor in real time, obtains the return torque during the return process, and completes the performance test and recording of the product to be tested; Step 5: At the end of the test, the lifting mechanism (4) is raised to below the connecting plate (10) of the motion decoupling mechanism (2), the upper part (8) of the wheel axle fixing seat is removed to separate the wheel axle from the connecting plate (10) of the decoupling mechanism (2), and then the lifting mechanism (4) is used to reset the wheel axle.

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