Dynamic torsional fatigue durability test bed and test method for belt pulley decoupler

Abstract

The invention belongs to the technical field of testing, and provides a belt pulley decoupler dynamic torsional fatigue durability test bench and a test method.The belt pulley decoupler and a belt pulley are installed on the test bench, and the belt pulley and the belt pulley decoupler are in driving connection through a belt; and the torque loader and the belt pulley are coaxially arranged, and the torque loader is used for loading the required test torque to the belt pulley decoupler from the belt pulley through the belt. Compared with the prior art, the device has the advantages that by adjusting the position of the variable frequency motor and the size of the included angle, the rotating speed fluctuation amplitude input into the belt pulley decoupler is changed, and meanwhile different sensors are used for collecting rotating speed and fluctuation signals transmitted by the variable frequency motor and the belt pulley decoupler; the dynamic torsional fatigue endurance test of the belt pulley decoupler at any rotating speed, any set torque and torque fluctuation state is completed under the condition of simulating the specified engine rotating speed, specified transmitted torque and specified torque fluctuation amplitude of the hybrid electric vehicle.

Description

Technical Field

[0001] The invention belongs to the field of testing technology, and in particular relates to a dynamic torsional fatigue endurance test bench and a testing method for a pulley decoupler. Background Art

[0002] With the continuous progress and development of hybrid vehicles, the complexity and diversity of vehicles are also increasing. In this context, the performance stability of the pulley decoupler, one of the key components in the engine front-end accessory drive (FEAD) system, under various working conditions has become particularly important. This is because the pulley decoupler not only has to withstand the mechanical stress caused by conventional starting, acceleration, deceleration and other working conditions, but also has to adapt to the additional loads brought by hybrid mode switching, such as motor assistance, energy recovery and other situations.

[0003] The main function of the pulley decoupler is to provide a buffer and isolation between the engine and the accessories, reducing the transmission of vibration and noise generated by the engine to the accessory system, thereby extending the service life of the accessories and improving the overall comfort of the vehicle. However, in hybrid mode, due to the frequent switching between the electric system and the internal combustion engine system, the load and vibration mode borne by the decoupler become more complex and unpredictable.

[0004] In order to verify whether the pulley decoupler can work reliably for a long time under various operating conditions of hybrid vehicles, it must be subjected to strict dynamic torsional fatigue durability tests. The currently disclosed Chinese patent number is: CN110261085A, and the patent name is: A test bench for testing the durability of pulley decouplers, which mainly tests the fatigue life of pulley decouplers under different working conditions by controlling the speed and forward and reverse rotation of the motor. However, the overall components of the test bench are relatively complex, and it is impossible to load the test torque on the pulley decoupler through the change of the torque loader, and it is impossible to adjust the speed fluctuation amplitude input to the pulley decoupler to perform dynamic torque fatigue durability tests, and ultimately it cannot meet the performance requirements throughout the vehicle life cycle. This is crucial to ensuring the quality and reliability of hybrid vehicles, and is also one of the key factors to ensure end-user satisfaction. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is: to propose a pulley decoupler dynamic torsional fatigue durability test bench that can simulate the operation of a hybrid vehicle under specific conditions, and a pulley decoupler dynamic torsional fatigue durability test bench and a test method that can complete dynamic torsional fatigue durability tests of pulley decouplers under different rotation speeds, different set torques and torque fluctuation conditions.

[0006] The technical solution adopted by the present invention to solve the technical problem is to provide a pulley decoupler dynamic torsion fatigue durability test bench, comprising: a pulley decoupler and a pulley mounted on the test bench, the pulley and the pulley decoupler being connected by a belt drive; A torque loader, which is coaxially arranged with the pulley, and is used to load the required test torque from the pulley to the pulley decoupler through the belt; A variable frequency motor and a universal coupling, wherein the variable frequency motor is used to provide a power source with adjustable speed, and the variable frequency motor can move freely along the radial direction and axial direction of the pulley on the test bench; one end of the universal coupling is connected to the variable frequency motor, and the other end is connected to the pulley decoupler, The universal coupling and the output end of the variable frequency motor form an angle that can change with the movement of the variable frequency motor, which is used to adjust the speed fluctuation amplitude input to the pulley decoupler; and the loading test torque of the pulley decoupler can be adjusted by the torque loader.

[0007] In the above-mentioned dynamic torsional fatigue endurance test bench for a pulley decoupler, a first rotating shaft is connected to the pulley decoupler, a first rotating shaft is provided with a first signal tooth, and a first speed sensor is provided on the test bench on one side of the first signal tooth. The first signal tooth transmits the speed and fluctuation signal of the variable frequency motor transmitted through the universal coupling, and is detected by the first speed sensor.

[0008] In the above-mentioned pulley decoupler dynamic torsional fatigue endurance test bench, the bottom wall of the belt is also movably pressed against a tensioning wheel, and the tensioning wheel can be moved in the height direction of the test bench to adjust the tension of the belt.

[0009] In the above-mentioned pulley decoupler dynamic torsional fatigue endurance test bench, the pulley is connected to a second rotating shaft, and a torque sensor is also provided on the second rotating shaft. The torque sensor is used to transmit the torque loaded by the torque loader and the torque fluctuation signal caused by the speed fluctuation.

[0010] In the above-mentioned dynamic torsional fatigue endurance test bench for a pulley decoupler, a second signal tooth is arranged on the second rotating shaft, and a second speed sensor is arranged on one side of the second signal tooth on the test bench. The second signal tooth is used to transmit the speed and fluctuation signal transmitted to the pulley after vibration reduction by the pulley decoupler, and is detected by the second speed sensor.

[0011] In the above-mentioned pulley decoupler dynamic torsional fatigue endurance test bench, a slider is provided at the bottom of the variable frequency motor, a slide rail is provided on the test bench, and the slider is movably connected to the slide rail.

[0012] In the above-mentioned pulley decoupler dynamic torsional fatigue endurance test bench, the test bench is also provided with a detector located on one side of the belt, and the detector is used to detect the noise generated when the belt shakes.

[0013] In the above-mentioned pulley decoupler dynamic torsional fatigue endurance test bench, the fluctuation signal is based on the rotation frequency of the variable frequency motor, and the formula is as follows: Assume that the input shaft speed of the variable frequency motor is , the output speed of the first shaft is , the angle between the universal coupling and the output shaft of the variable frequency motor is , the angular position of the input shaft of the variable frequency motor .

[0014] According to kinematics, the unevenness of the velocity transmitted by a single universal joint can be deduced.

[0015] The derivation process is as follows:

[0016] By deduction, it can be obtained that the speed of the output shaft of the universal coupling has a fluctuating characteristic, and the average value of the speed fluctuation is The amplitude of the fluctuation is , the frequency of fluctuation is twice the rotation frequency.

[0017] The technical solution adopted by the present invention to solve the technical problem is to also propose a testing method, comprising the steps of: S1, turning on the variable frequency motor, and changing the input pulley decoupler speed and fluctuation signal based on the variable frequency motor; S2, the pulley is connected to the pulley decoupler through a belt, and the pulley decoupler drives the pulley to rotate through the belt; S3, the first speed sensor obtains the speed and fluctuation signal of the pulley decoupler, and the second speed sensor obtains the speed and fluctuation signal of the pulley; based on the speed and fluctuation signal of the pulley decoupler and the speed and fluctuation signal of the pulley, a speed attenuation value and a fluctuation signal attenuation value are obtained; S4. A torque loader is connected to the pulley, and based on the torque loader changing the torque of the pulley, the pulley transmits the torque change to the pulley decoupler through the belt.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a pulley decoupler dynamic torsional fatigue durability test bench and test method. By adjusting the position of the variable frequency motor and the angle between the universal coupling and the output end of the variable frequency motor, the speed fluctuation amplitude input to the pulley decoupler can be changed. The first speed sensor is used to collect the speed and fluctuation signal transmitted by the variable frequency motor, while the second speed sensor collects the speed signal after vibration reduction by the pulley decoupler. The torque sensor records the torque fluctuation signal caused by the speed fluctuation caused by the torque loader, effectively simulating the dynamic torsional fatigue durability test of the pulley decoupler under the specified engine speed, specified transmitted torque and specified torque fluctuation amplitude of the hybrid vehicle, and completing the dynamic torsional fatigue durability test of the pulley decoupler under any rotation speed, any set torque and torque fluctuation state.

[0019] (2) The belt tension can be adjusted through the tensioner to further simulate the working conditions of the engine front end gear train. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of this application; Figure 2 It is a schematic diagram of the installation structure between the tensioner and the belt; Figure 3 It is a schematic diagram of input speed and output speed in the prior art; Figure 4 This is a speed comparison diagram based on the change in the angle between the output shaft of the variable frequency motor and the universal coupling in this application.

[0021] In the figure, 1. pulley decoupler; 2. pulley; 3. belt; 4. torque loader; 5. frequency conversion motor; 6. universal joint; 7. first rotating shaft; 8. first signal tooth; 9. first speed sensor; 10. tensioner; 11. second rotating shaft; 12. torque sensor; 13. second signal tooth; 14. second speed sensor; 15. detector. DETAILED DESCRIPTION

[0022] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0023] like Figures 1 to 4As shown, the present invention provides a dynamic torsional fatigue durability test bench for a pulley decoupler 1, comprising: a pulley decoupler 1 and a pulley 2 installed on the test bench, the pulley 2 being connected to the pulley decoupler 1 by a belt 3; a torque loader 4, which is coaxially arranged with the pulley 2, and the torque loader 4 is used to load the required test torque from the pulley 2 to the pulley decoupler 1 through the belt 3; a variable frequency motor 5 and a universal coupling 6, the variable frequency motor 5 is used to provide a power source with adjustable speed, and the variable frequency motor 5 can move freely along the radial direction and axial direction of the pulley 2 on the test bench; one end of the universal coupling 6 is connected to the variable frequency motor 5, and the other end is connected to the pulley decoupler 1, the universal coupling 6 and the output end of the variable frequency motor 5 form an angle that can change with the movement of the variable frequency motor 5, and is used to adjust the speed fluctuation amplitude input to the pulley decoupler 1; and the loading test torque of the pulley decoupler 1 can be adjusted by the torque loader 4.

[0024] In this embodiment, the variable frequency motor 5 can be Figure 1 The direction indicated by the arrow is relatively slid on the test bench (not shown in the figure) to adjust the position of the variable frequency motor 5. It is worth noting that the present solution can realize a dynamic test with a rotation speed through the variable frequency motor 5. Specifically, the output shaft of the variable frequency motor 5 and the universal coupling 6 form a Figure 1 As shown in the horizontal angle α, when the position of the above-mentioned variable frequency motor 5 changes, the size of the horizontal angle α changes accordingly, thereby realizing the change of the torque fluctuation amplitude of the pulley decoupler 1. That is to say, the variable frequency motor 5 in the structure is changed from a variable frequency motor 5 with torque fluctuation in the traditional technology, so that the pulley decoupler 1 can receive the speed and fluctuation signal transmitted by the variable frequency motor 5 via the universal coupling 6; similarly, under the transmission of the belt 3, after the pulley decoupler 1 is damped (a spring is installed inside the pulley decoupler 1, and the spring is used for damping), the speed and fluctuation model transmitted from the belt 3 to the pulley 2 are fed back by the pulley 2, and finally the attenuation degree after the pulley 2 and the pulley decoupler 1 are compared to determine whether the specified use requirements are met. Moreover, the test torque of the pulley 2 can be changed by the torque loader 4, and the torque of the pulley decoupler 1 is also changed under the transmission of the belt 3, thereby realizing the test bench simulating the hybrid vehicle at a specified engine speed, a specified transmitted torque and a specified torque fluctuation amplitude, and realizing the dynamic torque fatigue endurance test of the pulley decoupler 1 at any rotation speed, any set torque and torque fluctuation state.

[0025] A first rotating shaft 7 is connected to the pulley decoupler 1, and a first signal tooth 8 is provided on the first rotating shaft 7. A first speed sensor 9 is provided on one side of the first signal tooth 8 on the test bench. The first signal tooth 8 transmits the speed and fluctuation signal of the frequency conversion motor 5 through the universal coupling 6, and is detected by the first speed sensor 9.

[0026] like Figure 1 As shown, after adjusting the position of the variable frequency motor 5, the size of the horizontal angle α of the universal coupling 6 can be changed, thereby adjusting the speed fluctuation amplitude input to the pulley decoupler 1. In this process, since the first signal tooth 8 and the pulley decoupler 1 are coaxially arranged, the first signal tooth 8 can transmit the speed and fluctuation signal transmitted by the variable frequency motor 5 through the universal coupling 6, and finally receive it through the first speed sensor 9 and compare it with the data on the external device, so as to determine whether the torque fluctuation amplitude and rotation speed meet the use requirements.

[0027] A second rotating shaft 11 is connected to the pulley 2, and a torque sensor 12 is also provided on the second rotating shaft 11. The torque sensor 12 is used to transmit the torque loaded by the torque loader 4 and the torque fluctuation signal caused by the speed fluctuation; a second signal tooth 13 is provided on the second rotating shaft 11, and a second speed sensor 14 is provided on the test bench and is located on one side of the second signal tooth 13. The second signal tooth 13 is used to transmit the speed and fluctuation signal transmitted to the pulley 2 after the pulley decoupler 1 reduces vibration, and is detected by the second speed sensor 14.

[0028] like Figure 1 and Figure 2 As shown, after the speed fluctuation amplitude of the pulley decoupler 1 is adjusted accordingly due to the change of the above-mentioned horizontal angle α, the speed and fluctuation of the pulley decoupler 1 after vibration reduction can be transmitted to the pulley 2 by the belt 3 under the compression change of the spring (not shown in the figure) in the pulley decoupler 1. Similarly, since the pulley 2 and the second signal tooth 13 are coaxially arranged, the speed and fluctuation signal transmitted to the pulley 2 via the belt 3 can be transmitted to the second speed sensor 14 under the transmission of the second signal tooth 13. By comparing the information received by the first speed sensor 9 with the information received by the second speed sensor 14, the corresponding speed attenuation value and fluctuation attenuation value can be obtained.

[0029] Furthermore, when the torque loader 4 changes the torque of the pulley 2 through the second rotating shaft 11 (the change can be achieved under any set torque force), the torque value of the pulley 2 can be detected in real time through the torque sensor 12, and the torque of the pulley decoupler 1 is also changed under the transmission of the belt 3, ultimately realizing the dynamic torsional fatigue endurance test of the pulley decoupler 1 under any set torque and torque fluctuation state.

[0030] Preferably, in this embodiment, a tensioning wheel 10 is movably pressed against the bottom wall of the belt 3, such as Figure 2 As shown, the tensioning wheel 10 can achieve vertical displacement by means of a hydraulic cylinder or a pneumatic cylinder, thereby adjusting the tensioning degree of the tensioning wheel 10 on the belt 3, and finally achieving the tensioning force simulating the front end gear train of the engine.

[0031] Preferably, the present solution also provides a detector 15 (similar to a microphone, not shown in the figure) located on one side of the belt 3 on the test bench, and the detector 15 is used to detect the noise generated when the belt 3 is in a shaking state during operation, so as to determine whether it meets the usage requirements of the customer.

[0032] Preferably, the variable frequency motor 5 is placed on the test bench. Figure 1 It can move freely in the direction indicated by the arrow. In this embodiment, a slider (not shown in the figure) is provided at the bottom of the variable frequency motor 5, and a slide rail is provided on the test bench. The slide rail is similar to an I-shaped structure. The slider is movably connected to the slide rail to effectively achieve the torque fluctuation amplitude by changing the size of the horizontal angle α of the universal coupling 6 after the position of the variable frequency motor 5 is adjusted. The overall structure is simple and the operation is convenient and fast, which provides convenience for adjusting the torque fluctuation amplitude during the test. Preferably, the maximum value of the angle α is 25°, and the maximum sliding distance of the slider in the length direction of the slide rail is preferably 208mm.

[0033] In this test bench, a cross-axis universal joint coupling is used to simulate the second-order excitation of the engine (the second-order excitation mainly refers to the vibration and noise of a specific frequency generated by the engine during operation). In addition, the fluctuation signal in this embodiment is based on the rotation frequency of the variable frequency motor 5, and the formula is as follows: Assume that the input shaft speed of the variable frequency motor 5 is , the output speed of the first rotating shaft 7 is , the angle between the universal coupling 6 and the output shaft of the variable frequency motor 5 is , the angular position of the input shaft of the variable frequency motor 5 .

[0034] According to kinematics, the unevenness of the velocity transmitted by a single universal joint can be deduced.

[0035] The derivation process is as follows:

[0036] By deduction, it can be obtained that the speed of the output shaft of the universal coupling 6 has a fluctuation characteristic, and the average value of the speed fluctuation is The amplitude of the fluctuation is , the frequency of fluctuation is twice the rotation frequency.

[0037] In addition, after simulating the motion characteristics of the universal joint 6 using MATLAB, the following can be obtained: Figure 3 to Figure 4 As shown in the results, the output shaft of the variable frequency motor 5 in the prior art is often directly connected to the first rotating shaft 7 on the pulley decoupler 1 coaxially. When the input speed of the variable frequency motor 5 is constant at 100 rpm, the output speed is always within the same range of fluctuations. Figure 3 The present embodiment is different from the previous one in that a universal coupling 6 structure is added. When the output shaft of the variable frequency motor 5 is also at a constant input speed of 100 rpm, the placement position of the variable frequency motor 5 on the test bench can be adjusted by adjusting the slider and the slide rail. Figure 1 The size of the horizontal angle α of the universal coupling 6 is shown in FIG. 1 , and when α is 5°, 10°, 15°, or 20°, as shown in FIG. Figure 4 As shown, the speed fluctuation amplitude outputted by the output end of the universal coupling 6 (i.e., the end away from the variable frequency motor 5) also changes accordingly, which further proves that under the adjustment of the speed and position of the variable frequency motor 5, changing the horizontal angle α of the universal coupling 6 can complete the dynamic torque fatigue endurance test of the pulley 2 fuel saver at any rotation speed and torque fluctuation amplitude. From this, we can also conclude that: for the frequency modulation method: the speed fluctuation frequency outputted by the cross-axis universal coupling 6 is twice the stable speed of the variable frequency motor 5, and the frequency modulation can be achieved by adjusting the speed of the variable frequency motor 5; for the amplitude modulation method: the fluctuation amplitude of the output speed is adjusted by adjusting the installation angle of the cross-axis universal coupling 6, and the installation angle α of the universal coupling 6 is changed by the slider rail in the test bench.

[0038] This solution is based on the above-mentioned pulley decoupler 1 dynamic torsional fatigue durability test bench, and also provides a testing method, including the following steps: S1, turning on the variable frequency motor 5, and changing the speed and fluctuation signal of the input pulley decoupler 1 based on the variable frequency motor 5; S2, the pulley 2 is connected to the pulley decoupler 1 through the belt 3, and the pulley decoupler 1 drives the pulley 2 to rotate through the belt 3; S3, the first speed sensor 9 obtains the speed and fluctuation signal of the pulley decoupler 1, and the second speed sensor 14 obtains the speed and fluctuation signal of the pulley 2; based on the speed and fluctuation signal of the pulley decoupler 1 and the speed and fluctuation signal of the pulley 2, the speed attenuation value and the fluctuation signal attenuation value are obtained; S4 , the torque loader 4 is connected to the pulley 2 , and based on the torque loader 4 changing the torque of the pulley 2 , the pulley 2 transmits the torque change to the pulley decoupler 1 through the belt 3 .

[0039] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0040] In addition, in the present invention, descriptions such as "first", "second", "one", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0041] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A pulley decoupler dynamic torsional fatigue durability test bench, characterized in that: include: A pulley decoupler and a pulley mounted on the test bench, wherein the pulley is connected to the pulley decoupler via a belt drive; A torque loader, which is coaxially arranged with the pulley, and is used to load the required test torque from the pulley to the pulley decoupler through the belt; A variable frequency motor and a universal coupling, wherein the variable frequency motor is used to provide a power source with adjustable speed, and the variable frequency motor can move freely along the radial direction and axial direction of the pulley on the test bench; one end of the universal coupling is connected to the variable frequency motor, and the other end is connected to the pulley decoupler, The universal coupling and the output end of the variable frequency motor form an angle that can change with the movement of the variable frequency motor, and is used to adjust the speed fluctuation amplitude input to the pulley decoupler; The loading test torque of the pulley decoupler can be adjusted by the torque loader.

2. A pulley decoupler dynamic torsional fatigue durability test bench according to claim 1, characterized in that: The pulley decoupler is connected to a first rotating shaft, on which a first signal tooth is arranged, and the test bench is provided with a first speed sensor located on one side of the first signal tooth, through which the first signal tooth transmits the speed and fluctuation signal of the variable frequency motor transmitted through the universal joint, and detects the speed and fluctuation signal through the first speed sensor.

3. The pulley decoupler dynamic torsional fatigue durability test bench according to claim 1, characterized in that: The bottom wall of the belt is also movably pressed against a tensioning wheel, and the tensioning wheel can move in the height direction of the test bench to adjust the tension of the belt.

4. The pulley decoupler dynamic torsional fatigue durability test bench according to claim 2, characterized in that: The pulley is connected to a second rotating shaft, and a torque sensor is also arranged on the second rotating shaft. The torque sensor is used to transmit the torque loaded by the torque loader and the torque fluctuation signal caused by the speed fluctuation.

5. A pulley decoupler dynamic torsional fatigue durability test bench according to claim 4, characterized in that: A second signal tooth is arranged on the second rotating shaft, and a second speed sensor is arranged on one side of the second signal tooth on the test bench. The second signal tooth is used to transmit the speed and fluctuation signal transmitted to the pulley after vibration reduction by the pulley decoupler, and is detected by the second speed sensor.

6. The pulley decoupler dynamic torsional fatigue endurance test bench according to claim 1, characterized in that: A slider is provided at the bottom of the variable frequency motor, a slide rail is provided on the test bench, and the slider is movably connected to the slide rail.

7. The pulley decoupler dynamic torsional fatigue endurance test bench according to claim 1, characterized in that: The test bench is also provided with a detector located at one side of the belt, and the detector is used to detect the noise generated when the belt shakes.

8. The pulley decoupler dynamic torsional fatigue durability test bench according to claim 4, characterized in that: The fluctuation signal is based on the rotation frequency of the variable frequency motor, and the formula is as follows: Assume that the input shaft speed of the variable frequency motor is , the output speed of the first shaft is , the angle between the universal coupling and the output shaft of the variable frequency motor is , the angular position of the input shaft of the variable frequency motor . According to kinematics, the non-uniformity of the velocity transmitted by a single universal joint can be deduced. The derivation process is as follows: By deduction, it can be obtained that the speed of the output shaft of the universal coupling has a fluctuating characteristic, and the average value of the speed fluctuation is The amplitude of the fluctuation is , the frequency of fluctuation is twice the rotation frequency.

9. A test method, applied to a pulley decoupler dynamic torsional fatigue endurance test bench according to any one of claims 1 to 8, characterized in that: The steps include: S1, turning on the variable frequency motor, and changing the input pulley decoupler speed and fluctuation signal based on the variable frequency motor; S2, the pulley is connected to the pulley decoupler through a belt, and the pulley decoupler drives the pulley to rotate through the belt; S3, the first speed sensor obtains the speed and fluctuation signal of the pulley decoupler, and the second speed sensor obtains the speed and fluctuation signal of the pulley; based on the speed and fluctuation signal of the pulley decoupler and the speed and fluctuation signal of the pulley, a speed attenuation value and a fluctuation signal attenuation value are obtained; S4. A torque loader is connected to the pulley, and based on the torque loader changing the torque of the pulley, the pulley transmits the torque change to the pulley decoupler through the belt.

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