A test bench for a pendulum damper

Abstract

The application discloses a kind of pendulum damper test bench, comprising: mid self-calibration device, power device, limiting device, pressure sensor, the mid self-calibration device is used to drive pendulum damper piston rod to do reciprocating motion, the power device is for the mid self-calibration device Power, the limiting device is used to determine the safe boundary of pendulum damper movement, pressure sensor is installed on pendulum damper, with the mid calibration device electric connection, for real-time monitoring the stress F of pendulum damper;Calculate the deviation ΔF of F and pendulum damper design force value, when ΔF>0.2%, mid self-calibration device adjusts the position of pendulum damper piston rod, until meet mid determination standard: ΔF<0.2%, continue 10 seconds.The application can carry out mid calibration, avoid pendulum damper piston rod initial deviation, reduce error, limit for different working conditions and different pendulum damper, reduce damage to pendulum damper.

Description

Technical Field

[0001] This invention relates to the field of aviation test equipment technology, specifically to a sway reduction test bench. Background Technology

[0002] Modern aircraft experience high takeoff and landing speeds, and are subjected to lateral forces from the tires and runway, as well as lateral bending and torsional coupling of the struts. This causes self-excited vibrations in the nose wheel around the strut axis, resulting in shimmy. This phenomenon can cause fatigue damage to the landing gear, shorten the aircraft's service life, and the vibrations can affect pilot precision and reduce passenger comfort. Severe shimmy can lead to tire tearing, strut breakage, and in extreme cases, loss of aircraft control, causing serious accidents. To reduce this phenomenon, researchers have added shimmy dampers to the landing gear. These dampers convert the mechanical energy of the shimmy into heat energy for dissipation, thus suppressing the vibration amplitude.

[0003] The performance of the yaw damper affects the safety of aircraft takeoff, therefore, various tests are required to verify its performance. These include durability tests to verify if the damping meets design requirements, and damping characteristic tests to measure the damping coefficient. Both tests require fixing the yaw damper on a test bench. Taking the damping characteristic test as an example, the yaw damper is fixed in place by a fixture, and then an excitation is applied to the piston rod of the yaw damper via a fixture connection. The piston rod reciprocates within a set range. However, this method is prone to errors due to human intervention, resulting in installation accuracy that does not meet expectations, leading to inaccurate test results and reduced testing efficiency.

[0004] In current landing gear damper testing, many researchers have optimized and improved damper test benches. Chinese patent CN114354160A discloses a damper damping characteristic testing device. The damper is fixed between a torque sensor and a clamping fixture, and an air pump achieves constant loading to test the damper's damping characteristics. This test bench has a simple structure and low cost. However, this structure is not stable enough at high test frequencies. The lack of limiting mechanisms during start-up and operation can easily damage the internal structure of the damper. During different tests, the damper needs to be manually installed repeatedly, requiring a high level of skill from the operators and potentially leading to experimental errors and reduced accuracy. Furthermore, other types of damper test benches do not consider automatic centering and mechanical limiting mechanisms, making operation inconvenient during damper installation. This can easily cause initial piston rod offset, generating additional force and affecting the accuracy of test data. It may also reach the damper's structural stroke, causing damage. Research shows that no researchers have yet optimized or improved these aspects. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention proposes a oscillator test bench that enables center-position calibration during testing, avoids initial offset of the oscillator piston rod, reduces errors, limits movement under different operating conditions and for different oscillators, and minimizes damage to the oscillator.

[0006] The technical solution of the present invention: a oscillation damper durability test bench, characterized in that it comprises: A self-calibrating device for driving the piston rod of the oscillator to reciprocate; A power unit that provides power to the mid-position self-calibration device; A limiting device, which is used to determine the safety boundary of the oscillation damper's movement; A pressure sensor is mounted on the oscillator and electrically connected to the mid-position calibration device for real-time monitoring of the force F acting on the oscillator. Calculate the deviation ΔF between F and the design force value of the oscillator. When ΔF > 0.2%, the midpoint self-calibration device adjusts the position of the piston rod of the oscillator until the midpoint judgment criterion is met: ΔF < 0.2%, for 10 seconds.

[0007] In one embodiment, the center self-calibration device includes a dynamic loading cylinder, a calibration piston rod, a first baffle, a second baffle, a guide rod, a fixture, a laser displacement sensor, a hydraulic pipeline, and a servo valve. The dynamic loading cylinder and the guide rod are mounted on the fixture. The calibration piston rod is connected to the dynamic loading cylinder and to the oscillation damper piston rod, and is used to apply tension and pressure to the oscillation damper piston rod. The first baffle and the second baffle are fixed on the calibration piston rod and are slidably mounted on the guide rod.

[0008] In one embodiment, the power unit is a hydraulic pump station, which is connected to the dynamic loading cylinder via the hydraulic pipeline, and the servo valve is installed on the hydraulic pipeline.

[0009] In one embodiment, the limiting device includes a motor, a rotating shaft, a support base, a stop block, and a lead screw. The lead screw is rotatably mounted on the support base. One end of the rotating shaft is connected to the output shaft of the motor, and the other end of the rotating shaft is connected to the lead screw. The lower part of the stop block is mounted on the lead screw, and a guide rod passes through the upper part of the stop block. The stop block is slidably mounted on the guide rod. The laser displacement sensor is disposed on the stop block, and the stop block is disposed on the movement path of the baffle. When the displacement of the sway damper exceeds the limit for at least 5 cycles, the baffle and the stop block collide to trigger mechanical locking, and the hydraulic pump station and the dynamic loading cylinder stop abruptly.

[0010] In one embodiment, the limiting device is provided in two sets, namely a first limiting device and a second limiting device. The stop of the first limiting device is disposed close to the first baffle, and the stop of the second limiting device is disposed close to the second baffle. The two stops are located between the two baffles.

[0011] In one embodiment, a damper fixture is also included, the damper being mounted on the damper fixture.

[0012] In one embodiment, a test bench is also included, on which the center self-calibration device and the limiting device are mounted.

[0013] The self-calibration function of this invention uses a dynamic loading cylinder to drive the piston rod in low-speed reciprocating motion, monitoring the pressure sensor data at both ends of the damper in real time until the damper returns to center. This eliminates the assembly stress of the damper during traditional manual installation, avoids initial displacement of the piston rod, reduces errors, yields more accurate test results, and improves test efficiency. The limiting device can quickly limit the damper under different working conditions and for different dampers, preventing continuous impact from damaging internal components such as springs. Simultaneously, the test bench can perform various tests on the damper, such as durability tests, damping characteristic tests, and force and stroke detection tests. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the structure of each device in the present invention; Figure 3 This is a schematic diagram of the oscillation damper structure used in the experiment of this invention; In the diagram, 1. Stand, 2. Swing damper fixture, 3. Swing damper, 4. Pressure sensor, 5. Limiting device, 6. Mid-position self-calibration device, 7. Hydraulic pump station, 31. Swing damper piston rod, 32. Spring, 33. Housing, 41. Sensor fixture, 51. Motor, 52. Rotating shaft, 53. Support base, 54. Stop block, 55. Lead screw, 61. Fixture, 62. Dynamic loading cylinder, 63. Piston rod, 64. Servo valve, 65. First baffle, 66. Hydraulic pipeline, 67. Guide rod, 68. Laser displacement sensor, 69. Second baffle. Detailed Implementation

[0015] 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.

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0017] like Figures 1 to 3 As shown, this embodiment discloses a oscillation damper test bench, including a frame 1, an oscillation damper fixture 2, an oscillation damper 3, a pressure sensor 4, a limiting device 5, a centering self-calibration device 6, and a hydraulic pump station 7. The frame 1 is mounted on a ground rail; the oscillation damper fixture 2 is fixed on the frame 1, and the oscillation damper 3 is fixed on the oscillation damper fixture 2 by bolts. The pressure sensor 4 is mounted on the oscillation damper 3 through a sensor fixture 41. The pressure sensor 4 is used to measure the tension and pressure on the oscillation damper. The limiting device 5 is mounted on the frame 1 to set a safety boundary and prevent the oscillation damper 3 from being subjected to continuous impact. The centering self-calibration device 6 is mounted on the frame 1 to center the oscillation damper 3 before the test begins, eliminating the assembly stress of the oscillation damper 3. The hydraulic pump station 7 is mounted on the ground rail to provide power to the centering self-calibration device 6.

[0018] The damper 3 consists of a damper piston rod 31, a spring 32, and a housing 33. The housing 33 is mounted on the damper fixture 2. The damper piston rod 31 is kept in a neutral position under the action of the springs 32 at both ends in the working chamber. During operation, the damper piston rod 31 drives the springs 32 to compress and extend to consume energy.

[0019] The self-calibration device 6 consists of a fixture 61, a dynamic loading cylinder 62, a calibration piston rod 63, a servo valve 64, a first baffle 65, a hydraulic pipeline 66, a guide rod 67, a laser displacement sensor 68, and a second baffle 69. The fixture 61 is mounted on the frame 1, the dynamic loading cylinder 62 is mounted on the fixture 61, and the calibration piston rod 63 is connected to the dynamic loading cylinder 62 to apply tension and pressure to the damper piston rod 31. The hydraulic pipeline connects the hydraulic pump station 7 and the dynamic loading cylinder 62. The servo valve 64 is mounted on the dynamic loading cylinder 62 to precisely control the flow, pressure, and direction in the hydraulic pump station 7, ultimately controlling the damper 3 to extend and retract under stable pressure. The first baffle 65 and the second baffle 69 are fixed to the calibration piston rod 63. 3. The guide rod 67 is installed on the tooling 61 for guiding the first baffle 65 and the second baffle 69. The first baffle 65 and the second baffle 69 are slidably installed on the guide rod 67. The laser displacement sensor 68 is installed on the stop block 54 for measuring the distance between the baffle 65 and the stop block 54 and calculating the distance the stop block 54 moves according to the test requirements of the oscillator 3. The test bench should leave a gap to protect the oscillator and prevent the piston rod 31 of the oscillator from hitting the internal limit structure of the oscillator during the test.

[0020] The limiting device 5 consists of a motor 51, a rotating shaft 52, a support base 53, a stop 54, and a lead screw 55. The motor 51 is mounted on the frame 1, the support base 53 is mounted on the frame 1, the lower part of the stop 54 is mounted on the lead screw 55, a guide rod 67 passes through the upper part of the stop 54, the stop 54 is slidably mounted on the guide rod 67, and the lead screw 55 is rotatably mounted on the support base 53. The motor 51 slowly rotates, driving the lead screw 55 to rotate through the rotating shaft 52. The rotation of the lead screw 55 causes the stop 54 to move horizontally to a predetermined position, achieving the limiting purpose.

[0021] In this embodiment, the limiting device 5 is provided in two sets. The stops 54 of the two sets of limiting devices 5 are respectively set close to the first baffle 65 and the second baffle 69. The two stops 54 are located between the two baffles and are set on the movement path of the first baffle 65 and the second baffle 69. When the displacement of the damper 3 exceeds the limit for at least 5 cycles, the baffle and the stop block collide to trigger mechanical locking. Mechanical locking means that the hydraulic pump station and the dynamic loading cylinder stop moving to protect the product. The collision between the baffle and the stop block will generally cause a sudden change in the collected force. By setting an upper limit for force protection, when the force value collected exceeds the set upper limit after the collision, the test bench can trigger an emergency stop to protect the test product.

[0022] During the durability test of the oscillation damper in this invention: the oscillation damper 3 is fixed on the stand 1 by the oscillation damper fixture 2. The hydraulic pump station 7 is started, and the piston rod 63 of the dynamic loading cylinder 62 is controlled by the servo valve 64 to reciprocate at a low speed. The data of the pressure sensor 4 is monitored in real time, the force deviation is calculated, and the position of the calibration piston rod 63 is adjusted in real time according to the PID algorithm. The deviation ΔF between the pressure sensor 4 reading F and the design force value is less than 0.2% for 10 seconds to confirm that the oscillation damper piston rod 31 is in the neutral position. The working stroke and frequency of the dynamic loading cylinder 62 are set. The laser displacement sensor 68 measures the distance between the baffle and its adjacent stop and calculates the distance the stop 54 moves according to the set stroke. The motor 51 slowly rotates and drives the lead screw 55 to rotate through the rotating shaft 52. The rotation of the lead screw 55 drives the stop 54 to move horizontally to the predetermined position to complete the limit action. The servo valve 64 controls the flow, pressure and direction in the hydraulic pump station 7. Finally, the calibration piston rod 63 controls the oscillation damper piston rod 31 to extend and retract at a working frequency under stable pressure until the required number of tests is completed.

[0023] The PID algorithm is a feedback control strategy widely used in industrial control systems. It adjusts the output of the control system by combining three basic components: proportional (P), integral (I), and derivative (D) to achieve the desired control effect. The core of the PID algorithm lies in calculating the control output based on the current error, the accumulation of past errors, and the prediction of future errors.

[0024] During the force and stroke detection test of this invention: the damper 3 is fixed on the stand 1 by the damper fixture 2. The hydraulic pump station 7 is started, and the piston rod 63 of the dynamic loading cylinder 62 is controlled by the servo valve 64 to reciprocate at low speed. The data of the pressure sensor 4 is monitored in real time, the force deviation is calculated, and the position of the piston rod 63 is adjusted in real time according to the PID algorithm. The deviation ΔF between the pressure sensor 4 reading F and the design force value is less than 0.2% for 10 seconds to confirm that the damper piston rod 31 is in the neutral position. Starting from the neutral position, the damper piston rod 31 is slowly pulled. When the laser displacement sensor 68 changes, the force value corresponding to each stroke position is measured, and the displacement difference between the original position and the bottom of the extension is measured and recorded. The servo valve 64 reverses and compresses the damper piston rod 31 back to the neutral position. Starting from the neutral position, the damper piston rod 31 is slowly compressed. When the laser displacement sensor 68 changes, the force value corresponding to each stroke position is measured, and the displacement difference between the original position and the bottom of the compression is measured and recorded. When the compression reaches its limit, the test automatically ends, and the test data on the relationship between the force and stroke of the damper 3 are finally obtained (during the test, if the displacement sensor value does not change, the force value is increased by 20% on the basis of the current force value. If the displacement sensor value still does not change, it is considered that the piston rod tension / compression stroke has reached its limit).

[0025] When conducting the damping characteristic test of this invention: the damper 3 is fixed on the stand 1 by the damper fixture 2, the hydraulic pump station 7 is started, and the piston rod 63 of the dynamic loading cylinder 62 is controlled to reciprocate at low speed through the servo valve 64. The data of the pressure sensor 4 is monitored in real time, the force deviation is calculated, and the position of the piston rod 63 is adjusted in real time according to the PID algorithm. The deviation ΔF between the pressure sensor 4 reading F and the design force value is less than 0.2% for 10 seconds to confirm that the damper piston rod 31 is in the neutral position. The working stroke of the dynamic loading cylinder 62 is set. The laser displacement sensor 68 measures the distance between the baffle 65 and the stop 54 and calculates the distance the stop 54 moves according to the set stroke. The motor 51 slowly rotates and drives the lead screw 55 to rotate through the rotating shaft 52. The rotation of the lead screw 55 drives the stop 54 to move horizontally to the predetermined position to complete the limit action. The servo valve 64 controls the flow, pressure and direction in the hydraulic pump station 7. Finally, the piston rod 63 is calibrated to control the gradual application of sinusoidal vibrations at different frequencies and speeds to the damper piston rod 31. The damper 3 extends and retracts at different frequencies under stable pressure to obtain displacement-time data and calculate the damping coefficient of the damper 3.

[0026] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A test rig for a sway bar, characterized by, include: A self-calibrating device for driving the piston rod of the oscillator to reciprocate; A power unit that provides power to the mid-position self-calibration device; A limiting device, which is used to determine the safety boundary of the oscillation damper's movement; A pressure sensor, which is mounted on the oscillator and electrically connected to the mid-position calibration device, is used to monitor the force F on the oscillator in real time; and the oscillator tooling. The relative deviation ΔF between F and the design force value of the damper is calculated. When ΔF > 0.2%, the centering self-calibration device adjusts the position of the damper piston rod until the centering judgment criterion is met: ΔF < 0.2%, for 10 seconds. The centering self-calibration device includes a dynamic loading cylinder, a calibration piston rod, a first baffle, a second baffle, a guide rod, a fixture, a laser displacement sensor, hydraulic pipelines, and a servo valve. The dynamic loading cylinder and the guide rod are mounted on the fixture. The calibration piston rod is connected to the dynamic loading cylinder and the damper piston rod, and is used to apply tension and pressure to the damper piston rod. The first baffle and the second baffle are fixed on the calibration piston rod and are slidably mounted on the guide rod. The damper is mounted on the damper fixture.

2. The shimmy tester of claim 1, wherein: The power unit is a hydraulic pump station, which is connected to the dynamic loading cylinder through the hydraulic pipeline, and the servo valve is installed on the hydraulic pipeline.

3. The shimmy tester of claim 1, wherein: The limiting device includes a motor, a rotating shaft, a support base, a stop block, and a lead screw. The lead screw is rotatably mounted on the support base. One end of the rotating shaft is connected to the output shaft of the motor, and the other end of the rotating shaft is connected to the lead screw. The lower part of the stop block is mounted on the lead screw, and the guide rod passes through the upper part of the stop block. The stop block is slidably mounted on the guide rod. The laser displacement sensor is disposed on the stop block, and the stop block is disposed on the movement path of the baffle. When the displacement of the sway damper exceeds the limit for at least 5 cycles, the baffle and the stop block collide, triggering mechanical locking, and the hydraulic pump station and the dynamic loading cylinder stop abruptly.

4. The shimmy tester of claim 3, wherein: The limiting device is provided in two sets, namely a first limiting device and a second limiting device. The stop of the first limiting device is set close to the first baffle, and the stop of the second limiting device is set close to the second baffle. The two stops are located between the two baffles.

5. The oscillation damping test bench according to claim 1, characterized in that: It also includes a test bench, on which the center self-calibration device and the limiting device are mounted.

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