Non-road vehicle clutch durability test system based on PWM hydraulic valve control

Abstract

A non-road vehicle clutch durability test system based on PWM hydraulic valve control is particularly suitable for durability test and evaluation of a tractor wet clutch and comprises a driving motor, a tractor wet clutch box assembly, an inertia flywheel set, a PWM hydraulic control unit, a load simulation unit and a central controller. The driving motor, the tractor wet clutch box assembly, the inertia flywheel set and the load simulation unit are sequentially and coaxially connected, the PWM hydraulic control unit is connected with the tractor wet clutch box assembly through a hydraulic oil pipe, and control signals of the central controller are output to the driving motor, the PWM hydraulic control unit and the load simulation unit respectively. The scheme also relates to a test method based on the system, and the method utilizes the characteristics of fast response and high control precision of the PWM hydraulic valve to construct a test process capable of accurately simulating the complex working condition of field operation of the tractor, thereby realizing the durability test of the clutch assembly and the hydraulic control system.

Description

Technical Field

[0001] This invention relates to the field of non-road vehicle transmission system clutch testing technology, specifically a non-road vehicle clutch durability performance testing system and method based on PWM hydraulic valve control, which is particularly suitable for the durability performance testing and evaluation of tractor wet clutches. Background Technology

[0002] Tractors and other off-road vehicles operate in harsh environments with complex conditions. Their wet clutches in the transmission system are frequently subjected to shocks and slippage from starting, reversing, and shifting gears, making them vulnerable and critical components. The durability of the clutch directly affects the reliability and service life of the entire vehicle.

[0003] Currently, bench tests are commonly used to test clutch durability. However, traditional testing methods typically employ simple constant speed and constant torque loading, or simulate some operating conditions using a servo motor. These methods have the following shortcomings: (1) Low fidelity: It is difficult to accurately reproduce the dynamic pressure fluctuations of the hydraulic system and the engagement characteristics of the clutch under complex working conditions such as actual field operations and road transportation of tractors.

[0004] (2) Insufficient control precision: Using ordinary proportional valves or on / off valves for control results in slow response speed and poor linearity of pressure control, making it impossible to achieve precise simulation of the engagement process, resulting in a large deviation between the test results and the actual situation.

[0005] (3) Low testing efficiency: Since it is impossible to accurately simulate the worst working conditions, a long testing cycle is often required to achieve a certain testing equivalent, resulting in low efficiency.

[0006] (4) The evaluation dimension is too singular: it focuses too much on the life of the clutch itself and lacks effective means of assessing the collaborative durability of the entire hydraulic control system (such as valves and oil pumps).

[0007] The invention patent document with publication number CN 101819089B discloses a "tractor wet clutch test bench and its control method". It uses digital and intelligent technology to simulate the working process of tractor wet clutch. The operation process is simple and convenient. However, its test conditions are relatively fixed and lack the ability to adaptively construct conditions specific to non-road vehicles.

[0008] Patent document CN 105302117B discloses a "performance testing method for a dual-clutch hydraulic control system." This method uses an electromagnetic PWM valve assembly to control the clutch oil pressure, tests the error between the set control pressure and the actual oil pressure, and then determines the qualification of the tested dual-clutch hydraulic control system by comparing the actual error percentage coefficient distribution with the standard error percentage coefficient distribution. This invention focuses on the clutch engagement and disengagement performance, and the tested object has a relatively simple function, making it unable to effectively evaluate the overall durability performance of the clutch.

[0009] Therefore, there is an urgent need for a testing system and method that can evaluate the durability of wet clutches and hydraulic control systems of off-road vehicles with high fidelity, high efficiency and low cost. Summary of the Invention

[0010] The purpose of this invention is to provide a durability performance testing system and method for non-road vehicle clutches based on PWM hydraulic valve control. This method utilizes the fast response and high control precision of PWM hydraulic valves to construct a test process that can accurately simulate the complex working conditions of tractors in the field, thereby realizing the durability performance testing of the clutch assembly and hydraulic control system.

[0011] The technical solution adopted in this invention is: a non-road vehicle clutch durability performance testing system based on PWM hydraulic valve control. The testing system includes a drive motor, a tractor wet clutch housing assembly, an inertial flywheel assembly, a PWM hydraulic control unit, a load simulation unit, and a central controller. The drive motor, tractor wet clutch housing assembly, inertial flywheel assembly, and load simulation unit are coaxially connected in sequence. The PWM hydraulic control unit is connected to the tractor wet clutch housing assembly through hydraulic oil pipes. The control signals of the central controller are output to the drive motor, the PWM hydraulic control unit, and the load simulation unit, respectively.

[0012] As a preferred embodiment, the PWM hydraulic control unit includes a high-frequency response PWM hydraulic valve, a pressure sensor, and a temperature sensor, used to receive PWM signals from the central controller and precisely control the clutch oil pressure.

[0013] As a preferred embodiment, the drive motor is used to simulate the power input of an engine, and its speed is adjusted by a central controller. The output shaft of the drive motor is connected to the shaft of the tractor wet clutch housing assembly in sequence through a torque and speed sensor and a universal drive shaft. The torque and speed sensor is used to measure the torque and speed parameters at the input end and transmit them to the central controller in real time.

[0014] As a preferred embodiment, the load simulation unit adopts the form of an electric dynamometer. According to the output instructions of the central controller, a programmable variable resistance torque is applied to the output end of the tractor wet clutch housing assembly to simulate the load of various classic working conditions during tractor field operations. The central controller is an industrial computer equipped with a high-performance PLC, which stores the standardized durability test load spectrum and automated test process, and has the ability to perform real-time data analysis and trend judgment.

[0015] This solution also includes a test method for a non-road vehicle clutch durability testing system based on PWM hydraulic valve control, the steps of which are as follows: S1. Based on actual field operation data of tractors, collect clutch engagement process parameters under typical working conditions, preprocess and extract features from the collected data, and construct a standardized durability test load spectrum with the duty cycle-time relationship of PWM control signal as the core. S2. Initialize the test system. The central controller sets the initial parameters according to the model of the clutch being tested. S3. The central controller calls the load spectrum constructed in step S1, cyclically controls the PWM hydraulic control unit and the load simulation unit, performs accelerated endurance testing, and synchronously collects test data. S4. At predetermined test cycle intervals, calculate the average sliding friction work, engagement and disengagement time, pressure build-up time, and deviations from the target values, and perform time-series trend analysis; when the analysis results exceed the preset threshold, issue an early warning and terminate the test. S5. After the test is terminated, the system automatically generates a test report, which includes the total sliding friction work, the number of durability cycles, the performance degradation curve, the wear condition analysis of key components, and the durability assessment of the hydraulic control valve.

[0016] As a preferred embodiment, in step S1, the parameters include engine speed, clutch target engagement pressure, engagement and disengagement speed and duration, output shaft torque, etc.; the load spectrum includes at least smooth engagement condition, rapid engagement condition, semi-clutch condition under load and impact load condition. As a preferred embodiment, in step S2, the initial parameters set include initial oil pressure, lubrication flow rate, oil temperature, drive motor speed, etc.; the inertia flywheel assembly is adjusted to the corresponding inertia value according to the model of the clutch under test and the test process requirements; the load simulation unit sets the initial load according to the target torque value in the load spectrum; the PWM hydraulic control unit drives the high-frequency response hydraulic valve according to the initial duty cycle signal to establish the initial oil circuit pressure.

[0017] As a preferred embodiment, step S3 is specifically performed as follows: S31. Read the target PWM duty cycle-time curve, target drive speed, and target load torque of the current cycle from the load spectrum; S32. The central controller sends a real-time changing duty cycle signal to the PWM hydraulic control unit to control the opening of the high-frequency response hydraulic valve, precisely adjust the oil flow and pressure entering the clutch piston, and simulate different clutch engagement speeds and engagement pressures. S33. The load simulation unit applies a reverse resistance torque according to the target load torque, while the inertia flywheel assembly is used to simulate the vehicle's rotational inertia. S34. In each test cycle, the actual working pressure, sliding friction work, input and output speed and torque, oil temperature, and control current and duty cycle feedback of the PWM valve are collected and recorded in real time.

[0018] As a preferred embodiment, step S4 is specifically performed as follows: S41. Calculate the average slip friction work, engagement / disengagement time, pressure build-up time, and deviation from the target value for multiple cycles in the current batch; whereby the average slip friction work is the average of the total slip friction work generated by all clutch engagement actions from the start of slip friction to full engagement during multiple cycles, divided by the total number of cycles, and is obtained by integrating the instantaneous power over the engagement time period: In equation (1), For average sliding friction work, P s (t) represents the instantaneous slip friction work, and T(t) represents the actual transmitted torque of the clutch. The input and output instantaneous slip velocity is given by k, where k is the number of cycles and t is the input and output instantaneous slip velocity. s t e During the engagement process, the clutch experiences slippage and is fully engaged at these moments. t is the sliding time in a single cycle; S42. Perform time-series trend analysis on performance indicators. If the average sliding friction work continues to increase, the engagement time is abnormally prolonged, or the pressure build-up time increases significantly, it is determined that the clutch friction pair or hydraulic control system has experienced performance degradation. In this step, the following quantitative judgment model is constructed to quantify the evaluation criteria: S421. To eliminate single-instance fluctuations and assess long-term performance degradation, the average slip friction work relative to the initial baseline value is defined as the average slip friction trend index η over N consecutive cycles. W Its expression is as follows: In the formula, η W This is an indicator of average friction trend. Let N be the average sliding friction work from the k-th cycle onwards. The baseline average friction work measured in the initial stage of the test (such as the first 100 cycles); S422. Degradation of hydraulic system performance (such as seal aging, valve core wear, etc.) will prolong pressure build-up time. The growth rate of this indicator is defined as the pressure build-up time delay rate η. t Its expression is as follows: In the formula, η t Establish a time delay rate for the pressure. This is the average time required for the actual oil pressure to reach 90% of the target value in the most recent N cycles starting from the k-th cycle, from the issuance of the control command to the actual oil pressure. To obtain the average time required from issuing the control command to the actual oil pressure reaching 90% of the target during the initial testing phase; S43. When the performance degradation index exceeds the preset threshold (such as the average friction trend index η) W and pressure build-up time delay rate η t If any indicator exceeds its preset threshold (C) W C t If the clutch temperature rises sharply or abnormal vibration occurs, the system will issue an early warning and automatically terminate the test, recording the current cumulative number of cycles as the durability life.

[0019] The beneficial effects of this invention are: To address the shortcomings of existing technologies, this solution provides a durability performance testing system and method for non-road vehicle clutches based on PWM hydraulic valve control. By implementing this solution, the following technical effects can be achieved: (1) High-fidelity simulation: By utilizing the high frequency response and high resolution characteristics of the PWM hydraulic valve, the complex dynamic engagement process of the clutch in actual tractor operation can be accurately reproduced, which improves the authenticity and accuracy of the durability test results.

[0020] (2) Accelerated endurance test: By constructing a standardized load spectrum that condenses a variety of harsh working conditions and strengthening key working conditions (such as half-clutch under load and impact load), the life of the clutch is accelerated and the test cycle is significantly shortened.

[0021] (3) System-level evaluation: This invention not only tests the durability of the clutch friction plate itself, but also simultaneously assesses the reliability and lifespan of the entire PWM hydraulic control circuit (including valves, sensors, and seals), providing more comprehensive system-level durability data.

[0022] (4) Intelligent and adaptive: Through real-time data acquisition and performance degradation analysis, the system can intelligently judge the status of the test piece, realize failure warning, avoid further damage to the equipment, and adaptively optimize the subsequent load spectrum based on the previous test results to improve test efficiency. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structural principle of the testing system described in this invention; Figure 2 for Figure 1 Schematic diagram of the wet clutch housing assembly of a medium-sized tractor; Figure 3 This is a general flowchart of the method described in this invention; Figure 4 This is a schematic diagram of the duty cycle-time curves of PWM control under four typical operating conditions constructed in this invention; Figure 5 This is a flowchart of the performance degradation assessment in this invention.

[0025] Reference numerals: 1. Drive motor; 2. Torque and speed sensor; 3. Bearing housing; 4. Tractor wet clutch housing assembly; 41. Housing fixture; 42. Input shaft; 43. Output shaft; 44. Control oil port; 45. Lubricating oil port; 5. Universal drive shaft; 6. Inertia wheel assembly; 7. Load simulation unit; 8. PWM hydraulic control unit; 9. Central controller. Detailed Implementation

[0026] The present invention will now be described in detail through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0027] It should be noted that, unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains; the words "a," "an," or "the" and similar terms used in the patent application specification and claims of this invention do not express a quantity limitation, but rather indicate the presence of at least one; the words "comprising" or "including" and similar terms indicate that the elements or objects preceding "comprising" or "including" cover the elements or objects listed following "comprising" or "including" and their equivalents, but do not exclude other elements or objects having the same function; The following is in conjunction with the appendix Figure 1-5 A detailed description of a durability testing system and method for off-road vehicle clutches based on PWM hydraulic valve control is provided below: A durability performance testing system for off-road vehicle clutches based on PWM hydraulic valve control is shown in the schematic diagram below. Figure 1 As shown, it mainly consists of a drive motor 1, a torque and speed sensor 2, a bearing housing 3, a tractor wet clutch housing assembly 4, a universal drive shaft 5, an inertia flywheel assembly 6, a load simulation unit 7, a PWM hydraulic control unit 8, and a central controller 9. The drive motor 1, the tractor wet clutch housing assembly 4, the inertia flywheel assembly 6, and the load simulation unit 7 are connected coaxially in sequence. The PWM hydraulic control unit 8 is connected to the tractor wet clutch housing assembly 4 through hydraulic oil pipes.

[0028] In this embodiment, the drive motor 1 is used to simulate the power input of an engine. Its speed can be precisely adjusted by the central controller 9. The output shaft of the drive motor 1 is directly connected to the torque and speed sensor 2, and then connected to the tractor wet clutch housing assembly 4 through the bearing seat 3 and the universal drive shaft 5. The torque and speed sensor 2 is used to measure the torque and speed parameters at the input end and transmit them to the central controller 9.

[0029] In this embodiment, the structural schematic diagram of the tractor wet clutch housing assembly 4 is as follows: Figure 2 As shown, the clutch under test is installed inside the housing fixture 41. Its input shaft 42 and output shaft 43 are respectively led out from both ends of the housing fixture 41 to connect the universal drive shafts 5 at both ends. A hydraulic valve block is installed on the outside of the housing fixture 41 and connected to the PWM hydraulic control unit 8. The control oil port 44 on the hydraulic valve block is used to connect the control oil circuit to provide clutch engagement oil pressure. The lubrication oil port 45 on the hydraulic valve block is used to provide a stable cooling flow for the clutch friction plate during the durability test.

[0030] In this embodiment, the inertia flywheel assembly 6 consists of multiple flywheel discs with different moments of inertia, mounted on the drive shaft. Its equivalent moment of inertia is configured according to the model of the clutch being tested to simulate the vehicle's moment of inertia. The inertia flywheel assembly 6 is fixed at both ends by bearing seats 3 and connected to the tractor wet clutch housing assembly 4 via a universal joint drive shaft 5 and a torque-speed sensor 2. The torque-speed sensor 2 is used to measure the torque-speed parameters at the output end.

[0031] In this embodiment, the load simulation unit 7 is in the form of an electric dynamometer. According to the instructions of the central controller 9, a programmable variable resistance torque is applied to the output end of the tractor wet clutch housing assembly 4 to simulate the load of various classic working conditions during tractor field operations.

[0032] In this embodiment, the PWM hydraulic control unit 8 includes a hydraulic oil source, a hydraulic pump, a high-frequency response PWM hydraulic valve, pressure and temperature sensors, etc. The hydraulic oil source and hydraulic pump are used to continuously provide hydraulic power and cooling flow to the control oil circuit and lubrication oil circuit; the high-frequency response PWM hydraulic valve receives PWM control signals from the central controller 9 and converts the electrical signals into precise and fast-responding oil pressure, thereby accurately controlling the engagement and disengagement process of the clutch; the pressure and temperature sensors are used to monitor and provide feedback on the oil status during testing in real time.

[0033] In this embodiment, the central controller 9 is an industrial computer equipped with a high-performance PLC, with a built-in high-speed data acquisition card and control algorithm software. It internally stores the standardized durability test load spectrum (i.e., PWM duty cycle-time curve) and automated test process, and has the ability to perform real-time data analysis and determine performance degradation trends.

[0034] This solution also includes a method for testing the durability of non-road vehicle clutches based on PWM hydraulic valve control. The overall flowchart of the testing method is shown below. Figure 3 As shown, the method includes the following steps: Step S1: Using a wet PTO clutch of a certain model of 120 horsepower tractor as the test object, sensors were installed in the transmission system of the actual tractor to collect data on plowing starts, gear shifting on the road, and reversing in place during field operations. After processing, a standardized 2-minute endurance cyclic load spectrum was generated. This load spectrum includes 4 smooth engagements (PWM duty cycle slowly increases from 10% to 60% for 2 seconds), 2 rapid engagements (duty cycle jumps from 5% to 80% within 0.5 seconds), 3 half-clutch conditions lasting 5 seconds (duty cycle fluctuates between 30% and 40%), and 1 simulated overload impact load (duty cycle instantly reaches 90%). The PWM control duty cycle-time curves for the four typical conditions are shown in the figure. Figure 4 As shown, the conditions are, in order: smooth engagement, rapid engagement, semi-clutching under load, and impact load.

[0035] Step S2: System initialization. Set the hydraulic oil temperature to 80±5℃ and adjust the initial inertia of the inertia flywheel assembly 6 to 6kg / m. 2 The drive motor 1 rotates at the tractor PTO clutch input speed of 1500 rpm. The PWM hydraulic control unit 8 provides an initial oil pressure of 2 MPa and a lubrication flow of 20 L / min to the tractor wet clutch housing assembly 4. The load simulation unit 7 presets an initial torque of 500 Nm.

[0036] Step S3: The central controller 9 begins to cyclically execute the 2-minute load spectrum obtained in step S1. During each engagement, the central controller 9 sends commands to the PWM hydraulic control unit 8 according to the preset duty cycle-time curve. The high-frequency response proportional valve in the PWM hydraulic control unit 8 precisely adjusts the valve core opening according to the duty cycle signal, controlling the pressure of the oil flowing to the clutch piston, thereby achieving the desired engagement smoothness or impact. Simultaneously, the load simulation unit 7 synchronously applies the corresponding resistance torque for different engagement conditions, and the inertia flywheel assembly 6 simulates the corresponding inertia of the entire vehicle.

[0037] Step S4: After every 100 cycles, the system executes step S4. The central controller 9 analyzes the data from the most recent 100 cycles and calculates the average sliding friction work per cycle. When the average sliding friction work is found to have increased by more than 15% compared to the initial value, or when the sliding friction work during a single engagement process fluctuates drastically, the system determines that the friction plates have suffered severe wear leading to performance degradation, and records the current total number of cycles as the accelerated durability cycle test life of the clutch. The flowchart for performance degradation assessment is as follows: Figure 5 As shown.

[0038] Step S5: After the test, the system outputs a report. In the initial stable phase of the test, the average sliding friction work per cycle is approximately 35,000~40,000 J, and the single-cycle engagement pressure build-up time is approximately 100~150 ms. As the test cycles continue, both of these indicators show an upward trend, indicating that after approximately 5,000 enhanced cycles, the friction material wear of the clutch reaches its limit, i.e., the average sliding friction trend index η. W Greater than 15%. At this point, the current pressure build-up time delay rate η t The failure rate of less than 2% demonstrates the durability of the hydraulic control system itself. This test, which took only one-third the time of traditional methods, effectively reproduced the failure modes encountered in real-world use.

[0039] The parts not described in detail in the above embodiments are existing technologies.

[0040] It should be noted that although the present invention has been described through the above embodiments, the present invention may have many other embodiments. Without departing from the spirit and scope of the present invention, those skilled in the art can obviously make various corresponding changes and modifications to the present invention, but all such changes and modifications should fall within the scope of protection of the appended claims and their equivalents.

Claims

1. A durability performance testing system for non-road vehicle clutches based on PWM hydraulic valve control, characterized in that: The test system includes a drive motor, a tractor wet clutch housing assembly, an inertial flywheel assembly, a PWM hydraulic control unit, a load simulation unit, and a central controller. The drive motor, tractor wet clutch housing assembly, inertial flywheel assembly, and load simulation unit are connected coaxially in sequence. The PWM hydraulic control unit is connected to the tractor wet clutch housing assembly via hydraulic oil pipes. The control signals of the central controller are output to the drive motor, the PWM hydraulic control unit, and the load simulation unit, respectively.

2. The non-road vehicle clutch durability testing system based on PWM hydraulic valve control according to claim 1, characterized in that: The PWM hydraulic control unit includes a high-frequency response PWM hydraulic valve, a pressure sensor, and a temperature sensor, used to receive PWM signals from the central controller and precisely control the clutch oil pressure.

3. The non-road vehicle clutch durability testing system based on PWM hydraulic valve control according to claim 1, characterized in that: The drive motor is used to simulate the power input of an engine. Its speed is adjusted by the central controller. The output shaft of the drive motor is connected to the shaft of the tractor wet clutch housing assembly in sequence through a torque and speed sensor and a universal drive shaft. The torque and speed sensor is used to measure the torque and speed parameters at the input end and transmit them to the central controller in real time.

4. The non-road vehicle clutch durability testing system based on PWM hydraulic valve control according to claim 1, characterized in that: The load simulation unit adopts the form of an electric dynamometer. According to the output instructions of the central controller, it applies a programmable variable resistance torque to the output end of the tractor wet clutch housing assembly to simulate the load of various classic working conditions during tractor field operations. The central controller is an industrial computer equipped with a high-performance PLC. It stores the standardized durability test load spectrum and automated test process, and has the ability to perform real-time data analysis and trend judgment.

5. The test method for the durability performance testing system of a non-road vehicle clutch based on PWM hydraulic valve control according to any one of claims 1-4, characterized in that: The steps are as follows: S1. Based on actual field operation data of tractors, collect clutch engagement process parameters under typical working conditions, preprocess and extract features from the collected data, and construct a standardized durability test load spectrum with the duty cycle-time relationship of PWM control signal as the core. S2. Initialize the test system. The central controller sets the initial parameters according to the model of the clutch being tested. S3. The central controller calls the load spectrum constructed in step S1, cyclically controls the PWM hydraulic control unit and the load simulation unit, performs accelerated endurance testing, and synchronously collects test data. S4. At predetermined test cycle intervals, calculate the average sliding friction work, engagement and disengagement time, pressure build-up time, and deviations from the target values, and perform time-series trend analysis; when the analysis results exceed the preset threshold, issue an early warning and terminate the test. S5. After the test is terminated, a test report is obtained, which includes the total sliding friction work, the number of durability cycles, the performance degradation curve, the wear condition analysis of key components, and the durability assessment of the hydraulic control valve.

6. The test method according to claim 5, characterized in that: In step S1, the parameters include engine speed, clutch target engagement pressure, engagement and disengagement speed and duration, output shaft torque, etc.; the load spectrum includes at least smooth engagement condition, rapid engagement condition, semi-clutch condition under load and impact load condition.

7. The test method according to claim 5, characterized in that: In step S2, the initial parameters set include initial oil pressure, lubrication flow rate, oil temperature, drive motor speed, etc.; the inertia flywheel assembly is adjusted to the corresponding inertia value according to the model of the clutch under test and the test process requirements; the load simulation unit sets the initial load according to the target torque value in the load spectrum; the PWM hydraulic control unit drives the high-frequency response hydraulic valve according to the initial duty cycle signal to establish the initial oil circuit pressure.

8. The test method according to claim 5, characterized in that: The specific process of step S3 is as follows: S31. Read the target PWM duty cycle-time curve, target drive speed, and target load torque of the current cycle from the load spectrum; S32. The central controller sends a real-time changing duty cycle signal to the PWM hydraulic control unit to control the opening of the high-frequency response hydraulic valve, precisely adjust the oil flow and pressure entering the clutch piston, and simulate different clutch engagement speeds and engagement pressures. S33. The load simulation unit applies a reverse resistance torque according to the target load torque, while the inertia flywheel assembly is used to simulate the vehicle's rotational inertia. S34. In each test cycle, the actual working pressure, sliding friction work, input and output speed and torque, oil temperature, and control current and duty cycle feedback of the PWM valve are collected and recorded in real time.

9. The test method according to claim 5, characterized in that: The specific process of step S4 is as follows: S41. Calculate the average slip friction work, engagement / disengagement time, pressure build-up time, and deviation from the target value for multiple cycles in the current batch; whereby the average slip friction work is the average of the total slip friction work generated by all clutch engagement actions from the start of slip friction to full engagement during multiple cycles, divided by the total number of cycles, and is obtained by integrating the instantaneous power over the engagement time period: In equation (1), For average sliding friction work, P s ( t To combine instantaneous gliding friction, T ( t The actual transmitted torque of the clutch is 0. The input and output instantaneous slip velocity. k t represents the number of iterations. s t e During the engagement process, the clutch begins to slip and then fully engages. , t The sliding time in a single cycle; S42. Perform time-series trend analysis on the performance indicators. If the average sliding friction work continues to increase, the engagement time is abnormally prolonged, or the pressure build-up time increases significantly, it is determined that the performance of the clutch friction pair or the hydraulic control system has deteriorated. S43. When the performance degradation index exceeds the preset threshold or the clutch temperature rises sharply or abnormal vibration occurs, the system issues an early warning and automatically terminates the test, recording the current cumulative number of cycles as the durability life.

10. The test method according to claim 9, characterized in that: In step S42, the following quantitative judgment model is constructed to quantify the evaluation criteria: S421. To eliminate single-instance fluctuations and assess long-term performance degradation, a continuous... N Within each cycle, the growth rate of the average friction work relative to the initial baseline value is the average friction trend index. η W Its expression is as follows: In the formula, η W This is an indicator of average friction trend. For from the first k The next cycle begins closest N Average sliding friction work per cycle This is the baseline average sliding friction work measured in the initial stage of the test; S422. Degradation of hydraulic system performance (such as seal aging, valve core wear) will prolong pressure build-up time; the growth rate of this indicator is defined as the pressure build-up time delay rate. η t Its expression is as follows: In the formula, ηt Establish a time delay rate for the pressure. For from the first k The next cycle begins closest N The average time required for each cycle from issuing a control command to the actual oil pressure reaching 90% of the target. The average time required from issuing the control command to the actual oil pressure reaching 90% of the target was measured in the initial stage of the test.

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