A P2 configuration electric drive transmission fatigue life verification test method and test condition conversion design method

Abstract

The present invention provides a P2 configuration electric drive transmission fatigue life verification test method and a test condition conversion design method. On the one hand, by matching the actual road spectrum working condition load, it corrects the situation that some working conditions may be over-assessed and other working conditions are missing; secondly, through the fatigue damage equivalence principle, the test is accelerated. On the other hand, by using the automatic program control script during the working condition assessment, the possibility of test failure caused by human error is avoided, and the efficiency of the working condition operation is improved. The present invention is used to verify whether the reliability of all load-bearing components of the electric drive transmission P2 motor, gear shaft system, bearing, clutch and housing meets the design requirements, which is convenient for discovering design and product defects and rectifying them in advance to ensure the progress of project development.

Description

Technical Field

[0001] The present invention relates to the field of transmission reliability testing, and in particular to a fatigue life verification testing technology for a P2 configuration electric drive transmission. Background Art

[0002] With the increasingly stringent fuel consumption and emission regulations, the market share of hybrid vehicles is gradually increasing. As a hybrid technology route to achieve energy conservation and emission reduction, P2 configuration electric drive transmission is being vigorously developed by major companies. However, there is little research on the fatigue life verification of P2 configuration electric drive transmission. As a key link in the transmission system of P2 configuration hybrid vehicles, P2 configuration electric drive transmission has more problems than traditional transmission fatigue life. There are more problems that need to be verified, such as motor drive spline wear, P2 bearing retainer fracture, synchronizer fracture, electric drive transmission bearing damage, and electric drive transmission main reduction damage.

[0003] The traditional transmission fatigue life test only stipulates the target number of cycles of the speed and torque of the fixed input shaft of each gear, without energy recovery reverse drag working condition and P2 motor verification, which is different from the actual road spectrum working condition. Some working conditions may be over-tested while other working conditions are missing. In order to better develop the P2 configuration electric drive transmission, it is necessary to conduct fatigue life verification research on the P2 configuration electric drive transmission, optimize the input shaft cycle target, and accelerate the load spectrum conversion test condition test research.

[0004] Existing patent document CN114611228A discloses a method, system, storage medium and device for determining a transmission load spectrum, and a method for determining a transmission load spectrum; patent document CN113255055A discloses a transmission bench test load spectrum generation method based on vehicle dynamics simulation, and designs a transmission original load spectrum extraction and bench test load spectrum production method; patent document CN111766062A discloses a load spectrum loading control method for a FF transmission test bench. None of them designs the control of the P2 configuration electric drive transmission conversion bench test conditions, acceleration tests, and automated execution conditions. Summary of the invention

[0005] The purpose of this invention is to design a fatigue life verification test method for a P2 configuration electric drive transmission and a conversion design method for test conditions, which are used to verify whether the reliability of all load-bearing components of the electric drive transmission P2 motor, gear shaft system, bearings, clutch and housing meet the design requirements, so as to facilitate the discovery of design and product defects and make early corrections to ensure the progress of project development.

[0006] The technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a conversion design method for fatigue life verification test conditions of a P2 configuration electric drive transmission, which includes generating a load spectrum of the P2 configuration electric drive transmission and converting the test conditions.

[0008] (1) Generation of load spectrum of P2 electric drive transmission, including:

[0009] Construct a comprehensive road spectrum: Specifically, construct a road spectrum that includes urban, suburban, highway, and mountain road conditions, and the road condition weights are configured according to development goals.

[0010] Data collection: Select models equipped with benchmark powertrains to collect actual measured original road spectrum data;

[0011] The number of input shaft cycles under torque corresponding to the forward and reverse drag of each gear of the transmission is formed: data processing, extracting the torque-speed matrix of each gear, converting it into a torque-speed matrix, obtaining the corresponding torque damage, and forming the number of input shaft cycles under torque corresponding to the forward and reverse drag of each gear of the transmission.

[0012] Form a multi-stage bench test load spectrum: The number of input shaft cycles obtained through data collection is multiplied by the safety factor of development experience, and the development and design goals are expanded to cover the development and application of product transmissions to form a multi-stage bench test load spectrum.

[0013] N i总 =∑N iW1 +∑N iW2 +∑N iW3 +∑N iW4

[0014] N i总 , represents the total number of input shaft cycles in gear i measured by constructing the road spectrum;

[0015] ∑N iW1 , represents the number of cycles of the input shaft in gear I measured under urban road conditions;

[0016] ∑N iW2 , represents the number of cycles of the input shaft in gear I measured in suburban road conditions;

[0017] ∑N iW3 , represents the number of cycles of the input shaft in gear I measured under high-speed road conditions;

[0018] ∑N iW4 , represents the number of cycles of the input shaft in gear I measured under mountain road conditions;

[0019] i represents gear position 1, 2, 3, ..., R.

[0020] (2) Conversion of test conditions, including:

[0021] Using Miner's law and fatigue damage accumulation theory, the fixed speed and torque segmented load spectrum of each gear is converted; by increasing the verification torque to the design load-bearing torque, it is converted into a one-stage bench test load spectrum, forming a one-stage bench test condition of forward and reverse dragging for each gear, and determining the input speed. The input torque is the bench drive torque + P2 motor torque, and the number of cycles for each gear is the working condition time.

[0022] The conversion formula for the number of cycles under different torques is as follows:

[0023] N b =(T a / T b ) ^e *N a

[0024] N a , represents the number of input shaft cycles when the torque T is a;

[0025] N b , represents the number of input shaft cycles when the torque T is b;

[0026] e represents the negative inverse of the slope between the low cycle cycle and the fatigue limit inflection point of the bearing material.

[0027] In a second aspect, the present invention provides a P2 configuration electric drive transmission fatigue life verification test method, which comprises the following steps:

[0028] Test preparation: Install the P2-configuration electric drive transmission assembly onto the test bench according to the vehicle status.

[0029] Test access inspection: including product status confirmation, test version data inspection, test control boundary condition confirmation, and test bench on-site safety inspection.

[0030] Electric transmission running-in.

[0031] Initial performance test: Perform performance tests before fatigue life tests according to performance test items such as P2 motor system peak torque test and transmission efficiency test.

[0032] Working condition operation: The working condition is designed by adopting the conversion design method described above. Fatigue life test working condition operation is carried out on each gear, which is divided into four large cycles. The forward dragging working condition verification is carried out first, in the order from low speed gear → high speed gear → R gear, and then the reverse dragging working condition verification is carried out.

[0033] Performance retest: Performance retest after fatigue life test is carried out according to performance test items such as P2 motor system peak torque test and transmission efficiency test.

[0034] Finally, the test is analyzed.

[0035] According to one embodiment of the present invention, the operating condition includes:

[0036] Step 1: Power on, start the electronic pump, control the P2 motor to start preheating, control the rack drive motor speed to 0, and control the load motor torque to 0.

[0037] Step 2: Execute the forward dragging condition, close the K0 clutch and the K1 clutch, and engage the 1st gear; the linkage test bench controls the load motor to set the speed control mode, and the control frame drive motor to set the torque control mode, and drags the input speed to the target speed of the condition. At the same time, the linkage test bench drive motor and the communication PEU (motor controller) control the P2 motor to set the torque to the target torque of the condition, and run the 1 / 4 cycle block condition verification.

[0038] Step 3: Link the test bench drive motor and the communication PEU (motor controller) to control the P2 motor to set the torque to 0, control the load motor speed to 0, close the K0 clutch and K2 clutch, engage the 2nd gear, and complete the 1 / 4 cycle block 2nd gear working condition verification in the same control method as step 2.

[0039] Step 4: Link the test bench drive motor and the communication PEU (motor controller) to control the P2 motor to set the torque to 0 and control the load motor speed to 0. Close the K0 clutch and K1 clutch, engage the 3rd gear, and complete the 1 / 4 cycle block 3rd gear working condition verification in the same control method as step 2.

[0040] The other even-numbered gears are verified according to step three, and the odd-numbered gears and R gear are verified according to step four.

[0041] Step 5: Repeat steps 2 to 4 until four large-cycle forward towing working condition verifications are completed; then perform reverse towing working condition verification, and repeat steps 2 to 4 in the control mode until four large-cycle reverse towing working condition verifications are completed.

[0042] The beneficial effects of the present invention are as follows:

[0043] On the one hand, the present invention corrects the situation where some working conditions may be over-assessed and other working conditions are missing by matching the actual road spectrum working condition load; secondly, through the fatigue damage equivalence principle, the test is accelerated and the verification cycle is shortened by 70%, which can also achieve the purpose of verifying the reliability of all load-bearing components such as the electric drive transmission P2 motor, gear shaft system, bearings, clutch and housing. The present invention avoids the possibility of test failure due to human error and improves the efficiency of working condition operation by using automatic program-controlled scripts during working condition assessment. In the early stage of project development, it can verify whether the P2 configuration electric drive transmission meets the reliability design requirements, and can discover design and product defects in advance and make timely corrections to ensure the progress of project development. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The foregoing and other aspects of the present application may be more fully understood through the detailed description given below with reference to the accompanying drawings, in which:

[0045] Figure 1 This is a schematic diagram of the layout of the P2 configuration electric drive transmission test bench.

[0046] Figure 2 Design a conversion diagram for the fatigue life verification test condition of the P2 configuration electric drive transmission.

[0047] Figure 3 This is a flow chart of the automatic control method for the fatigue life verification test condition of the P2 configuration electric drive transmission.

[0048] Figure 4 This is the operating condition diagram for the fatigue life verification test of the P2 configuration electric transmission.

[0049] Figure 5 This is the flow chart of the fatigue life verification test of the P2 configuration electric transmission. DETAILED DESCRIPTION

[0050] The principle and specific implementation methods of the present invention are further described in detail below with reference to the specific drawings.

[0051] See also Figure 1 This embodiment provides the structure of the test system for durability verification of the P2 configuration electric drive transmission, which is mainly composed of the P2 configuration electric drive transmission assembly 11, the test bench equipment and its control system. Among them, the P2 motor 2, the transmission 3, the K0 clutch 4, the K1 clutch 7, and the K2 clutch 8 constitute the P2 configuration electric drive transmission assembly 11, the output end of the transmission 3 is connected to the No. 1 bench load motor 12 through the half shaft 14, and the other output end of the transmission 3 is connected to the No. 2 bench load motor 13 through the half shaft 15. The TCU (transmission control unit) 9 and the PEU (motor controller) 5 constitute the control system, and the bench drive motor 1, the battery simulator 6, the temperature control system 10, the No. 1 bench load motor 12, the No. 2 bench load motor 13, etc. constitute the test bench equipment. In addition, the test bench should also be equipped with a data acquisition system that can accurately measure and collect the test parameters that need to be collected, such as temperature, pressure, speed, etc., and the bench control system can communicate with the electric drive transmission assembly product control system TCU and PEU.

[0052] See also Figure 2 This embodiment provides a P2 configuration electric drive transmission fatigue life verification test condition design conversion method, which mainly includes the generation of the P2 configuration electric drive transmission load spectrum and the conversion of the test condition. Take the P2 configuration 6-speed electric drive transmission as an example:

[0053] (1) Generation of load spectrum of P2 electric drive transmission:

[0054] First, a road spectrum including urban, suburban, highway and mountain road conditions is constructed, and the weights of the above road conditions are configured according to the development goals. A vehicle model equipped with a benchmark powertrain is selected to collect the original road spectrum data 17. The collected signals must include drive shaft speed torque, vehicle speed, hybrid mode, shift mode, gear, brake, accelerator pedal opening, motor speed torque, engine speed torque, actual powertrain torque, etc. After data processing, the torque-speed matrix of each gear is extracted and converted into a torque-speed matrix to obtain the corresponding torque damage, forming the number of input shaft cycles under torque corresponding to the forward and reverse drag of each gear of the transmission 18.

[0055] By multiplying the safety factor by development experience, the 240,000-kilometer development and design target is expanded to cover the development and application product transmissions, forming a multi-stage bench test load spectrum.

[0056] Through the above, the target mileage of the transmission development under the constructed road spectrum comprehensive working conditions, the number of input shaft cycles in each gear can be processed to form a multi-stage bench test load spectrum.

[0057] N i总 =∑N iW1 +∑N iW2 +∑N iW3 +∑N iW4

[0058] N i总 , represents the total number of input shaft cycles in gear i measured by constructing the road spectrum;

[0059] ∑N iW1 , represents the number of cycles of the input shaft in gear I measured under urban road conditions;

[0060] ∑N iW2 , represents the number of cycles of the input shaft in gear I measured in suburban road conditions;

[0061] ∑N iW3 , represents the number of cycles of the input shaft in gear I measured under high-speed road conditions;

[0062] ∑N iW4 , represents the number of cycles of the input shaft in gear I measured under mountain road conditions;

[0063] i, represents gear position 1, 2, 3, 4, 5, 6, R

[0064] 2) Conversion of test conditions

[0065] Miner's law and fatigue damage accumulation theory are used to convert the fixed speed and torque segmented load spectrum of each gear 19. By increasing the verification torque to the design load torque, it is converted into a one-stage bench test load spectrum, shortening the test cycle and accelerating the test, forming a one-stage bench test condition of forward and reverse drag in each gear 20, and determining the input speed, input torque (bench drive torque + P2 motor torque), and the number of cycles (condition time) of each gear.

[0066] The conversion formula for the number of cycles under different torques is as follows:

[0067] N b =(T a / T b ) ^e *N a

[0068] N a , represents the number of input shaft cycles when the torque T is a;

[0069] N b , represents the number of input shaft cycles when the torque T is b;

[0070] e represents the negative inverse of the slope between the low cycle cycle and the fatigue limit inflection point of the bearing material.

[0071] The following is a specific example of a 6-speed electric drive transmission with P2 configuration to further illustrate the working condition conversion design:

[0072] The torque-speed matrix of each gear extracted by the measured data is known and converted into a torque-speed matrix to obtain the corresponding torque damage, forming the number of input shaft cycles under torque corresponding to the forward and reverse drag of each gear of the transmission N = input speed * running time t * 60, forming a multi-stage bench test load spectrum, with a total running time of 437.6h, as shown in the following table:

[0073]

[0074]

[0075] According to the fatigue damage accumulation theory, the conversion formula for the number of cycles under different torques is N b =(T a / T b ) ^e *N a , e takes the ball bearing coefficient as 3, converts the multi-stage load of each gear into the design load-bearing torque, and converts it into the determined input speed, input torque (bench drive torque + P2 motor rated torque), number of cycles of each gear (working time), and the total operating time is 132.6h.

[0076]

[0077] In another embodiment of the present invention, a method for fatigue life verification test of a P2 configuration electric drive transmission is specifically described.

[0078] See also Figure 4 and Figure 5 , this embodiment is the detailed steps of the fatigue life verification test method of the P2 configuration electric drive transmission:

[0079] Test preparation 26: Assemble the motor 2, transmission 3, and K0 clutch 4 into the P2 configuration electric drive transmission assembly product 11 and install it on the test bench in the state of the whole vehicle, connect the output end of the transmission 3 to the No. 1 test bench load motor 12 and the No. 2 test bench load motor 13 with half shafts 14 and 15 respectively, connect the battery simulator 6 and the motor controller 5 to the motor 2 with high-voltage lines, debug the communication between the test bench and the motor controller 5 and the transmission control unit 9, use the pipeline connection of the product state and debug the cooling equipment such as water temperature and oil temperature, add an appropriate amount of lubricating oil to the transmission 3, debug the test bench to ensure that the electric drive transmission assembly can operate normally on the test bench.

[0080] Test entry inspection 27: The pre-test entry inspection shall be carried out in accordance with the electric drive transmission fatigue life test entry inspection rules, which shall mainly include product status confirmation, test version data inspection, test control boundary condition confirmation, test bench on-site safety inspection, etc.

[0081] Electric drive transmission running-in 28: According to the set running-in conditions, the P2 configuration electric drive transmission assembly is run-in from low gear to high gear for a certain period of time. During the running-in process, pay attention to controlling the oil temperature within the required range.

[0082] Preliminary performance test 29: Perform performance test before fatigue life test according to performance test items such as P2 motor system peak torque test and transmission efficiency test.

[0083] Working condition operation 30: fatigue life test working condition operation is carried out on each gear. Taking the 6-speed P2 configuration electric drive transmission as an example, the test is completed in four large cycles. The forward dragging condition is now carried out in the order from low speed gear → high speed gear → R gear; after completing the forward dragging condition, the reverse dragging condition is carried out.

[0084] This operating condition can be run by compiling a program script based on Python software to realize the automatic execution of the test condition. Figure 2 The specific idea is to open and execute the script program 21, configure the INCA test parameters and variable configuration 22, and realize communication with the TCU (transmission control unit) 9 and PEU (motor controller) 5. After completing the configuration, the option of executing the test condition 23 appears, and you can choose to execute the forward towing condition 24 or the reverse towing condition 25 according to the test progress.

[0085] The specific execution steps of the working condition are as follows:

[0086] Step 1: Power on, start the electronic pump, control the P2 motor 2 to start preheating, and control the transmission oil temperature within the normal working range. The test bench 16 controls the frame drive motor 1 speed to 0 and controls the load motors 12 and 13 torque to 0.

[0087] Step 2: Execute the forward dragging condition 24 in the script program, close the K0 clutch 4 and the K1 clutch 7, and engage the 1st gear. The linkage test bench 16 controls the load motors 12 and 13 to set the speed control mode, and the test bench drive motor 1 to set the torque control mode. The input speed is dragged to the target speed of the working condition within 20 seconds. At the same time, the test bench drive motor 1 and the communication PEU (motor controller) 5 are linked to control the P2 motor 2 to set the torque to the target torque of the working condition, and run the 1 / 4 cycle block working condition verification. Note: Each 1 / 4 cycle block is further divided into an appropriate number of small cycles according to the actual situation or design requirements. The torque is unloaded within 20 seconds between each small cycle, and after holding for 5 seconds, the torque is added within 20 seconds until the 1 / 4 cycle block working condition time of the gear is completed.

[0088] Step 3: Link the bench drive motor 1 and the communication PEU (motor controller) 5 to control the P2 motor 2 to set the torque to 0 respectively, and control the speed of the load motors 12 and 13 to 0. Close the K0 clutch 4 and K2 clutch 8, and engage the 2nd gear. Complete the 1 / 4 cycle block 2nd gear working condition verification in the same control method as the above step 2.

[0089] Step 4: Link the bench drive motor 1 and the communication PEU (motor controller) 5 to control the P2 motor 2 to set the torque to 0 respectively, and control the speed of the load motors 12 and 13 to 0. Close the K0 clutch 4 and K1 clutch 7, and engage the 3rd gear. Complete the 1 / 4 cycle block 3rd gear working condition verification in the same control method as the above step 2.

[0090] The linkage test bench drive motor 1 and the communication PEU (motor controller) 5 control the P2 motor 2 to set the torque to 0 respectively, and control the speed of the load motors 12 and 13 to 0. Close the K0 clutch 4 and K2 clutch 8, and engage the 4th gear. Complete the 1 / 4 cycle block 4th gear working condition verification in the same control method as the above step 2.

[0091] The linkage test bench drive motor 1 and the communication PEU (motor controller) 5 control the P2 motor 2 to set the torque to 0 respectively, and control the speed of the load motors 12 and 13 to 0. Close the K0 clutch 4 and the K1 clutch 7, and engage the 5th gear. Complete the 1 / 4 cycle block 5th gear working condition verification in the same control method as the above step 2.

[0092] The linkage test bench drive motor 1 and the communication PEU (motor controller) 5 control the P2 motor 2 to set the torque to the working condition of 0, and control the speed of the load motors 12 and 13 to 0. Close the K0 clutch 4 and the K2 clutch 8, and engage the 6th gear. Complete the 1 / 4 cycle block 6th gear working condition verification in the same control method as the above step 2.

[0093] The linkage test bench drive motor 1 and the communication PEU (motor controller) 5 control the P2 motor 2 to set the torque to 0 respectively, and control the speed of the load motors 12 and 13 to 0. Close the K0 clutch 4 and K2 clutch 8, and engage the R gear. Complete the 1 / 4 cycle block R gear working condition verification in the same control method as the above step 2.

[0094] Step 5: Repeat steps 2 to 4 until four large-cycle forward towing conditions are verified. Then perform reverse towing condition 25 verification, and repeat the control method of steps 2 to 4 until four large-cycle reverse towing conditions are verified.

[0095] Performance retest 31: Perform a performance retest after the fatigue life test according to the performance test items such as P2 motor system peak torque test and transmission efficiency test.

[0096] Post-test analysis 32: Issue a test report on the electric drive transmission test bench and analytical evaluation.

[0097] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. Although certain embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be construed as being limited to the embodiments described herein. Instead, these embodiments are provided to provide a more thorough and complete understanding of the present application. It should be understood that the drawings and embodiments of the present application are only for exemplary purposes and are not intended to limit the scope of protection of the present application.

[0098] In addition, it should be understood that the various steps recorded in the method implementation mode of the present application can be performed in different orders, and / or performed in parallel. In addition, the method implementation mode may include the appended claims. The scope of the present application is not limited in this respect. The various specific technical features described in the above-mentioned specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further explain various possible combinations. In addition, the various different embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the ideas disclosed in the present invention, they should also be regarded as the contents disclosed in the present invention.

Claims

1. The conversion design method of the fatigue life verification test condition of the P2 configuration electric drive transmission is characterized by: Includes the generation of load spectrum of P2 configuration electric drive transmission and conversion of test conditions; (1) Generation of load spectrum of P2 electric drive transmission: Construct a comprehensive working condition road spectrum; Data collection: Select models equipped with benchmark powertrains to collect actual measured original road spectrum data; Form the number of input shaft cycles under torque corresponding to forward and reverse drag of each gear of the transmission: data processing, extract the torque-speed matrix of each gear, convert it into a torque-speed matrix, obtain the corresponding torque damage, and form the number of input shaft cycles under torque corresponding to forward and reverse drag of each gear of the transmission; Form a multi-stage bench test load spectrum: By multiplying the number of input shaft cycles by the safety factor of development experience, the development and design goals are expanded to cover the development and application product transmission, forming a multi-stage bench test load spectrum: N i总 =∑N iW1 +∑N iW2 +∑N iW3 +∑N iW4 N i总 , represents the total number of input shaft cycles in gear i measured by constructing the road spectrum; ∑N iW1 , represents the number of cycles of the input shaft in gear I measured under urban road conditions; ∑N iW2 , represents the number of cycles of the input shaft in gear I measured in suburban road conditions; ∑N iW3 , represents the number of cycles of the input shaft in gear I measured under high-speed road conditions; ∑N iW4 , represents the number of cycles of the input shaft in gear I measured under mountain road conditions; i, represents gear position 1, 2, 3, 4, 5, 6, ..., R; (2) Conversion of test conditions Miner's law and fatigue damage accumulation theory are used to convert the fixed speed and torque segmented load spectrum of each gear. By increasing the verification torque to the design load torque, it is converted into a one-stage bench test load spectrum, forming a one-stage bench test condition of forward and reverse dragging for each gear, and determining the input speed. The input torque is the bench drive torque + P2 motor torque, and the number of cycles for each gear is the working condition time. The conversion formula for the number of cycles under different torques is as follows: N b =(T a / T b ) ^e *N a N a , represents the number of input shaft cycles when the torque T is a; N b , represents the number of input shaft cycles when the torque T is b; e represents the negative inverse of the slope between the low cycle cycle and the fatigue limit inflection point of the bearing material.

2. The conversion design method of the fatigue life verification test condition of the P2 configuration electric drive transmission according to claim 1 is characterized in that: The construction of a comprehensive working condition road spectrum is to construct a road spectrum including urban, suburban, highway, and mountain road working conditions, and the road condition weights are configured according to the development goals.

3. The conversion design method of the fatigue life verification test condition of the P2 configuration electric drive transmission according to claim 1 is characterized in that: The data acquisition signals include drive shaft speed torque, vehicle speed, hybrid power mode, shift mode, gear position, brake, accelerator pedal opening, motor speed torque, engine speed torque, and actual powertrain torque.

4. A P2 configuration electric drive transmission fatigue life verification test method, characterized in that: The steps include: Test preparation: Install the P2-configuration electric drive transmission assembly onto the test bench according to the vehicle status; Test access inspection: including product status confirmation, test version data inspection, test control boundary condition confirmation, and test bench on-site safety inspection; Electric drive transmission running-in; Initial performance test: Perform performance tests before fatigue life tests according to the P2 motor system peak torque test, transmission efficiency test and other performance test items; Working condition operation: the working condition is designed by the conversion design method described in any one of claims 1 to 3, and fatigue life test working condition operation is carried out for each gear, which is divided into four large cycles, firstly the forward dragging working condition verification is carried out in the order of low speed gear → high speed gear → R gear, and then the reverse dragging working condition verification is carried out; Performance retest: Perform performance retest after fatigue life test according to the performance test items such as P2 motor system peak torque test and transmission efficiency test; Post-test analysis.

5. The fatigue life verification test method of the P2 configuration electric drive transmission according to claim 4 is characterized in that: The operating conditions include: Step 1: Power on, start the electronic pump, control the P2 motor to start preheating, control the rack drive motor speed to 0, and control the load motor torque to 0; Step 2: Execute the forward dragging condition, close the K0 clutch and the K1 clutch, and engage the 1st gear; the linkage test bench controls the load motor to set the speed control mode, and the control frame drive motor to set the torque control mode, and drags the input speed to the target speed of the working condition. At the same time, the linkage test bench drive motor and the communication PEU (motor controller) control the P2 motor to set the torque to the target torque of the working condition, and run the 1 / 4 cycle block working condition verification; Step 3: Link the test bench drive motor and the communication PEU (motor controller) to control the P2 motor to set the torque to 0 respectively, control the load motor speed to 0, close the K0 clutch and the K2 clutch, and engage the 2nd gear. Complete the 1 / 4 cycle block 2nd gear working condition verification in the same control method as step 2; Step 4: Link the test bench drive motor and the communication PEU (motor controller) to control the P2 motor to set the torque to 0 respectively, and control the load motor speed to 0; close the K0 clutch and the K1 clutch, and engage the 3rd gear, and complete the 1 / 4 cycle block 3rd gear working condition verification in the same control method as step 2; The other even-numbered gears and R gear are verified according to step 3, and the odd-numbered gears are verified according to step 4; Step 5: Repeat steps 2 to 4 until four large-cycle forward towing working condition verifications are completed; then perform reverse towing working condition verification, and repeat steps 2 to 4 in the control mode until four large-cycle reverse towing working condition verifications are completed.

6. The fatigue life verification test method of the P2 configuration electric drive transmission according to claim 5 is characterized in that: Each 1 / 4 cycle block is further divided into an appropriate number of small cycles according to actual conditions or design requirements. Between each small cycle, the torque is unloaded within 20 seconds, maintained for 5 seconds, and then torqued within 20 seconds until the 1 / 4 cycle block working time of the gear is completed.

7. The fatigue life verification test method of the P2 configuration electric drive transmission according to claim 5 is characterized in that: The working condition operation is based on Python software to compile program scripts to achieve automated execution of the test conditions.

Images