Transmission shaft calibration rack and transmission shaft torque test method in whole vehicle operation process

Abstract

The invention relates to a calibration method of a vehicle transmission assembly, in particular to a transmission shaft calibration rack and a transmission shaft torque test method in the whole vehicle operation process, and aims to solve the problem that an existing transmission calibration method cannot meet the torque test requirements of a whole vehicle under various complex operation conditions. The output torque strength of the transmission shaft cannot be accurately obtained, and the problems of whole vehicle NVH and strength are difficult to solve. The method comprises the following steps: 1) installing a transmission shaft to be calibrated; (2) torque is loaded to the driving motor and the load motor; 3) calibrating to obtain ri and ui; 4) obtaining a single calibration process ri-alpha i-Si corresponding relation; 5) obtaining a three-dimensional calibration data set; 6) obtaining a plurality of three-dimensional calibration data sets, and sorting to obtain a four-dimensional calibration data set; (7) the calibrated transmission shaft is assembled to the vehicle; and 8) calculating the output torque Tx of the transmission shaft at any moment. According to the method, forward and reverse torque loading is performed by using the driving motor and the load motor, and the calibration precision is high.

Description

Technical Field

[0001] The present invention relates to a calibration method for a vehicle transmission component, and particularly to a torque test method for a drive shaft calibration bench and a whole vehicle during operation. Background Art

[0002] The power train system refers to a device for transmitting power between the engine and the vehicle drive wheels. The torque transmitted by the power train is the power source for vehicle driving and is also closely related to the strength of key components in the vehicle and the vehicle NVH (Noise, Vibration, Harshness) data. If the torque impact and fluctuation transmitted by the power train are too large, it is extremely easy to cause failures of key components, cracking of the shells of related components, or NVH problems such as torsional vibration and knocking abnormal noises, which will seriously affect the safety and subjective feelings of drivers and passengers. Therefore, obtaining the true torque of the vehicle power train is of utmost importance in the vehicle development and fault diagnosis processes.

[0003] The sampling rate of the torque signal in the vehicle CAN (Controller Area Network) signal is usually 10Hz, which is much lower than the actual torque change frequency of the power train. In most working conditions, it is difficult to reflect the torque fluctuation and instantaneous torque impact phenomena of the power train. Considering the structural layout and installation space of the vehicle power train, testers usually arrange strain gauge bridges on the drive shaft, use wireless telemetry technology to measure the voltage signal output by the strain gauge bridges, and obtain the actual drive shaft torque of the vehicle through calibration to obtain the torque-voltage correspondence curve of the drive shaft. It can be seen that obtaining an accurate torque-voltage relationship of the drive shaft determines the accuracy of torque measurement.

[0004] Existing drive shaft torque calibration methods can be divided into two types: static calibration and dynamic calibration.

[0005] In the static calibration method, one end of the transmission shaft is usually fixed on the test bench, and the other end is loaded with torque by using weights and a torque wrench through the lever principle, or a motor is used for forward and reverse torque grading loading and unloading. For example, a transmission shaft torque calibration method disclosed in Chinese Patent CN105352643A includes the following steps: 1) Install the transmission shaft to be tested on the test bench; 2) Install a strain gauge wireless measurement system on the transmission shaft; 3) Apply torque to the transmission shaft and output the corresponding voltage value through the strain gauge wireless measurement system; 4) Establish a transmission shaft torque calibration model and calculate the calibration coefficient. However, the deficiencies of this patent are as follows: This patent needs to obtain the torque-voltage correspondence relationship through processes such as manual point selection and linear fitting, ignoring factors such as the dynamic hysteresis of the transmission shaft during the operation of the whole vehicle, the unbalanced bending moment at high speeds, non-linearity, and the torque-voltage difference during the loading and unloading processes, and cannot guarantee the accuracy of the transmission shaft torque collected during the dynamic operation of the whole vehicle.

[0006] In the dynamic calibration method, for example, Chinese Patent CN118583487 discloses a method for accurately obtaining the torque of an automotive transmission shaft during a whole vehicle test. This patent is based on the target working conditions and combines model simulation to simulate the load conditions of the transmission shaft, obtains the test loading curve, and obtains the corresponding rotational speed, torque, and voltage correspondence relationship in the time history. However, the deficiencies of this patent are as follows: The calibration data volume and workload of this method are strongly related to the simulated working conditions, and it is more suitable for specific test field test working conditions, and cannot meet the various working conditions of a large number of vehicles operating in different regions and with different driving habits on the market, affecting the efficiency and accuracy of problem-solving.

[0007] In summary, the existing transmission calibration methods cannot meet the torque test requirements of the whole vehicle under various complex operating conditions, and cannot accurately obtain the output torque strength of the transmission shaft, making it difficult to solve the NVH problem. Summary of the Invention

[0008] The purpose of the present invention is to solve the problem that the existing transmission calibration methods cannot meet the torque test requirements of the whole vehicle under various complex operating conditions, and cannot accurately obtain the output torque strength of the transmission shaft, making it difficult to solve the strength and NVH problems, and to provide a transmission shaft calibration bench and a method for testing the torque of the transmission shaft during the operation of the whole vehicle.

[0009] To achieve the above purpose, the technical solution provided by the present invention is:

[0010] A transmission shaft calibration bench, characterized in that:

[0011] It includes a base, a data acquisition system, a drive motor, a first reducer, a second reducer, and a load motor arranged on the base, and a rotational speed sensor and a wireless torque telemetry system whose output ends are electrically connected to the input end of the data acquisition system respectively;

[0012] The output end of the driving motor is connected to the input end of the first reducer through a first connecting shaft, and the output end of the load motor is connected to the input end of the second reducer through a second connecting shaft. A transmission shaft to be calibrated is installed between the output end of the first reducer and the output end of the second reducer;

[0013] The central axes of the first connecting shaft, the second connecting shaft and the transmission shaft are collinear;

[0014] The first reducer and the second reducer are respectively used to reduce the speed and increase the torque of the driving motor and the load motor; the rotational speed sensor is used to measure the rotational speed of the transmission shaft, and the wireless torque telemetry system is used to measure the voltage signal generated by the change of the loading torque of the transmission shaft. It includes a strain gauge bridge attached to the transmission shaft and a wireless transmission module connected to the output end of the strain gauge bridge, and a wireless receiving module electrically connected to the input end of the data acquisition system; the strain gauge bridge includes a plurality of strain gauges, and the wireless transmission module is used to transmit the data measured by the strain gauge bridge to the wireless receiving module.

[0015] At the same time, the present invention also provides a method for measuring the torque of the transmission shaft during the operation of the whole vehicle, which is characterized in that it includes the following steps:

[0016] Step 1: Assemble the above-mentioned transmission shaft calibration bench, install the transmission shaft to be calibrated between the output ends of the first reducer and the second reducer, then install a strain gauge bridge and a wireless transmission module at a preset position on the transmission shaft, and turn on the data acquisition system;

[0017] Step 2: Determine the preset rules for loading torques on the driving motor and the load motor;

[0018] The preset rules are implemented by the following formula: where, T I is the calibration torque, and its value is equal to 80% of the maximum designed working torque of the transmission shaft; T i is the loading torque of the driving motor during a single calibration, n is the number of segments of the calibration torque, i is the index of the loading torque for each calibration, and i = 0, 1, 2... n; is the load torque loaded by the load motor during calibration, and its value is equal to the vehicle running resistance torque under the calibrated load condition; j is the index of each load condition, j = 1, 2... m, and m is the number of load conditions of the vehicle to be calibrated; take j = 1;

[0019] Step 3: Start the driving motor and the load motor, and input the corresponding loading torque and load torque to the driving motor and the load motor respectively according to the preset rules to calibrate the transmission shaft, and obtain the change curve r i ;

[0020] Step 4: According to the curve of rotational speed varying with time r i , the output voltage curve u of the strain bridge i , calculate the angular acceleration curve α of the transmission shaft i , and the torque-voltage calibration coefficient curve S during a single calibration process i , where obtain the r i -α i -S i corresponding relationship

[0021] Step 5: Change the loading torque T of the driving motor i , and according to the methods of Step 3 and Step 4, obtain a total of n + 1 groups of different loading torques T i under the r i -α i -S i corresponding relationships Thus, obtain the three-dimensional calibration data set of r-α-S for the first calibration process where α is the angular acceleration of the transmission shaft, r is the rotational speed of the transmission shaft measured by the rotational speed sensor, and S is the torque-voltage calibration coefficient of the transmission shaft;

[0022] Step 6: Take j = 2, 3…m, and according to the methods of Step 3 to Step 5, respectively obtain the three-dimensional calibration data sets of r-α-S for the second, third…m-th calibration processes Thus, obtain the T o -r-α-S four-dimensional calibration data set of the transmission shaft where T o is the driving resistance under different vehicle load conditions;

[0023] Step 7: Assemble the calibrated transmission shaft onto the vehicle, and then install a strain gauge bridge, a wireless torque telemetry system, and a rotational speed sensor on the assembled transmission shaft to ensure that the rotational speed r of the transmission shaft at any moment during vehicle operation can be obtained x and the output voltage signal u of the strain gauge bridge x ;

[0024] Step 8: Calculate the angular acceleration curve α of the transmission shaft according to r x , x , calculate the output torque T of the transmission shaft at any moment according to the curve α x , the voltage signal u x and the four-dimensional calibration data set obtained in Step 6 , and complete the test x .

[0025] Furthermore, the signal sampling rates measured by the rotational speed sensor and the wireless torque telemetry system are always greater than or equal to 2000 Hz.

[0026] Furthermore, Step 3 is specifically as follows:

[0027] Start the calibration. When looking at the load motor from the drive motor, define the clockwise rotation direction of the transmission shaft as the positive direction. The rotational speed of the transmission shaft measured by the rotational speed sensor is r i , and the angular acceleration of the transmission shaft is α i ; First, input and apply a loading torque T in the positive direction to the drive motor system i , and apply a load torque in the negative direction to the load motor system When the transmission shaft reaches the maximum positive drive rotational speed of the transmission shaft designed for the whole vehicle , cancel the applied loading torque T of the drive motor i , and decelerate with the load torque ; When the rotational speed drops to 0, input and apply a loading torque T in the reverse direction to the drive motor i , and apply a load torque in the positive direction to the load motor until the rotational speed of the transmission shaft reaches the maximum negative rotational speed of the transmission shaft designed for the whole vehicle Then cancel the applied loading torque T input by the drive motor i , and decelerate with the load torque ; When the rotational speed of the transmission shaft drops to 0, stop the machine to complete a single calibration; record the rotational speed curve r of the transmission shaft during a single loading process i .

[0028] Furthermore, in Step 8, the output torque T of the transmission shaft at any moment x is calculated using the following formula:

[0029]

[0030] where is the vehicle driving resistance torque under the actual load condition of the whole vehicle, is the vehicle driving resistance torque under the calibrated load condition of the whole vehicle under which, the calibration coefficient corresponding to the rotational speed r x and the angular acceleration α x ; r p and r p+1 are the adjacent calibrated rotational speeds of the rotational speed r x ; α q and α q+1 are the adjacent calibrated angular accelerations of the angular acceleration α x ; and are respectively the vehicle calibrated load condition vehicle driving resistance torques adjacent to .

[0031] Further, in step 2, n = 5 and m = 3; when j = 1, the load condition of the whole vehicle corresponds to the no-load condition; when j = 2, the load condition of the whole vehicle corresponds to the half-load condition; when j = 3, the load condition of the whole vehicle corresponds to the full-load condition.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. The drive shaft calibration bench provided by the present invention has a simple structure, low cost, and convenient operation, and can quickly obtain accurate calibration data sets during calibration.

[0034] 2. The method for testing the drive shaft torque during the operation of the whole vehicle provided by the present invention can obtain the drive shaft torque under different vehicle states and operations through the calibration data set obtained by bench calibration, and is applicable to various regions, road conditions, and different driving operations during the actual operation of the whole vehicle, with strong generality and wide applicability.

[0035] 3. The method for testing the drive shaft torque during the operation of the whole vehicle provided by the present invention takes into account factors such as drive shaft dynamic hysteresis, unbalanced bending moment at high speeds, and non-linearity. At the same time, the driving motor and the load motor are used for forward and reverse torque loading, and factors such as torque-voltage differences during the loading and unloading processes of strain gauges are considered, resulting in high calibration accuracy.

[0036] 4. For the method for testing the drive shaft torque during the operation of the whole vehicle provided by the present invention, the preset rules in step 2 of the present invention comprehensively consider different load conditions and driving habits during the actual operation of the whole vehicle, segment the calibration torque of the drive shaft, and synchronously combine multiple typical load conditions of the whole vehicle, and perform multiple calibrations on the calibration bench to obtain the true torque-voltage calibration coefficients of the drive shaft under different loads and different torques, improving the reliability of the calibration data set, and ultimately improving the accuracy of torque testing under the working conditions of the whole vehicle.

[0037] 5. For the method for testing the drive shaft torque during the operation of the whole vehicle provided by the present invention, the number of segments n of the calibration torque and the number of load conditions m of the whole vehicle to be calibrated in steps 5 and 6 of the present invention can be flexibly adjusted according to the actual operation conditions of different test vehicles. On the premise of obtaining accurate calibration data sets, it is possible to avoid waste of bench resources caused by excessive setting of n or m, and improve the economy of the calibration process.

[0038] 6. For the method for testing the drive shaft torque during the operation of the whole vehicle provided by the present invention, the signal sampling rates of the rotational speed sensor, the wireless receiving module, the wireless transmitting module, and the data acquisition system in all steps of the present invention are always greater than or equal to 2000 Hz. Such a setting can accurately collect the angular acceleration and torque changes under conditions such as torsional vibration and impact of the whole vehicle, obtain the true load of the vehicle drivetrain, and can be used for strength verification of key components of the drivetrain, improving reliability. Description of the Drawings

[0039] Figure 1 This is a flowchart of an embodiment of the method for testing the torque of a drive shaft during the operation of a whole vehicle according to the present invention;

[0040] Figure 2 This is a schematic structural diagram of an embodiment of the drive shaft calibration bench according to the present invention;

[0041] Explanation of reference numerals:

[0042] 1 - Base, 2 - Driving motor, 3 - First reducer, 4 - Drive shaft, 5 - Second reducer, 6 - Load motor, 7 - Rotation speed sensor, 81 - Wireless receiving module, 82 - Wireless transmitting module, 9 - Data acquisition system. Detailed implementation manners

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0044] Embodiment 1

[0045] A drive shaft calibration bench, see Figure 2 , which includes a base 1, a data acquisition system 9, a driving motor 2, a first reducer 3, a second reducer 5 and a load motor 6 arranged on the base 1, and a rotation speed sensor 7 and a wireless torque telemetry system whose output ends are electrically connected to the input end of the data acquisition system 9 respectively; the output end of the driving motor 2 is connected to the input end of the first reducer 3 through a first connecting shaft, the output end of the load motor 6 is connected to the input end of the second reducer 5 through a second connecting shaft, and a drive shaft 4 to be calibrated is installed between the output end of the first reducer 3 and the output end of the second reducer 5; the central axes of the first connecting shaft, the second connecting shaft and the drive shaft 4 are collinear; the first reducer 3 and the second reducer 5 are used to decelerate and increase the torque of the driving motor 2 and the load motor 6 in sequence, and jointly with the driving motor 2 or the load motor to realize the control of the required torque and rotation speed; the rotation speed sensor 7 is used to test the rotation speed of the drive shaft 4, and the wireless torque telemetry system is used to test the voltage signal generated by the change of the loaded torque of the drive shaft 4, which includes a strain gauge bridge pasted on the drive shaft 4 and a wireless transmitting module 82 connected to the output end of the strain gauge bridge, and a wireless receiving module 81 electrically connected to the input end of the data acquisition system 9; the input end of the wireless receiving module 81 cooperates with the wireless transmitting module 82, the strain gauge bridge includes a plurality of strain gauges, and the wireless transmitting module 82 is used to transmit the data measured by the strain gauge bridge to the wireless receiving module 81.

[0046] At the same time, this embodiment also provides a method for testing the torque of a drive shaft during the operation of a whole vehicle, and its flowchart is shown in Figure 1 , including the following steps:

[0047] Step 1: Assemble the above-mentioned drive shaft calibration bench, install the drive shaft 4 to be calibrated between the output ends of the first reducer 3 and the second reducer 5, then install a strain gauge bridge and a wireless transmission module 82 at a preset position on the drive shaft 4, and turn on the data acquisition system 9;

[0048] Step 2: Determine the preset rules for loading torque on the drive motor 2 and the load motor 6;

[0049] The preset rules are implemented using the following formula: where, T I is the calibration torque, and its value is equal to 80% of the designed maximum working torque of the drive shaft 4; T i is the loading torque of the drive motor 2 during a single calibration, n is the number of segments of the calibration torque. In this embodiment, n = 5, i is the index of the loading torque for each calibration, and i = 0, 1, 2, 3, 4, 5; is the load torque loaded by the load motor 6 during calibration; j is the index of each load condition, j = 1, 2, 3, and m is the number of load conditions of the vehicle to be calibrated. In this embodiment, m = 3; take j = 1;

[0050] Step 3: Start calibration. Define that when looking from the drive motor 2 to the load motor 6, the clockwise rotation direction of the drive shaft 4 is the positive direction. The rotational speed sensor 7 measures the rotational speed of the drive shaft 4 as r i , and the angular acceleration of the drive shaft 4 is α i ; First, the drive motor system inputs a loading torque T i in the positive direction, and the load motor 6 system loads a load torque in the negative direction. When the drive shaft 4 reaches the maximum positive drive rotational speed of the designed vehicle drive shaft , cancel the loading torque T i of the drive motor 2, and decelerate with the load torque ; When the rotational speed drops to 0, the drive motor 2 inputs a loading torque T i in the reverse direction, and the load motor 6 loads a load torque in the positive direction until the rotational speed of the drive shaft 4 reaches the maximum negative rotational speed of the designed vehicle drive shaft Then cancel the loading torque T i input by the drive motor 2, and decelerate with the load torque ; When the rotational speed of the drive shaft 4 drops to 0, stop the machine to complete a single calibration; record the rotational speed curve r i， of the drive shaft 4 and the output voltage curve u i of the strain bridge during the single loading process;

[0051] Step 4: According to the rotational speed vs. time curve r i obtained in Step 3, calculate the angular acceleration curve α i, the torque-voltage calibration coefficient curve S during a single calibration process i , where obtain the single calibration process r i -α i -S i corresponding relationship

[0052] Step 5. Change the loading torque T of the drive motor 2 i , and according to the methods of Step 3 and Step 4, thus obtain a total of n + 1 groups of different loading torques T i under which r i -α i -S i corresponding relationships Organize to obtain the three-dimensional calibration data set of r-α-S for the first calibration process where α is the angular acceleration of the transmission shaft 4, r is the rotational speed of the transmission shaft 4 measured by the rotational speed sensor 7, and S is the torque-voltage calibration coefficient of the transmission shaft 4;

[0053] Step 6. Take j = 2, 3, and according to the methods of Step 3 to Step 5, respectively obtain the three-dimensional calibration data sets of r-α-S for the second and third calibration processes Organize to obtain the T o -r-α-S four-dimensional calibration data set of the transmission shaft 4 where T o is the driving resistance during different load conditions of the whole vehicle;

[0054] Step 7. Assemble the calibrated transmission shaft 4 onto the vehicle, and then install a strain gauge bridge, a wireless torque telemetry system, and a rotational speed sensor 7 on the assembled transmission shaft 4 to ensure that the rotational speed r of the transmission shaft can be obtained at any moment during the operation of the whole vehicle x and the output voltage signal u of the strain gauge bridge x ;

[0055] Step 8. According to r x calculate the angular acceleration curve α of the transmission shaft 4 x , According to the curve α x , the voltage signal u x and the four-dimensional calibration data set obtained in Step 6 calculate the output torque T of the transmission shaft 4 at any moment according to the preset formula x , test that the vehicle load is 2 / 3 of the full load, and the driving resistance of the whole vehicle is at this time

[0056] the output torque T of the transmission shaft 4 at any moment x is calculated using the following formula:

[0057]

[0058] Among them, is the vehicle driving resistance torque under the actual load condition of the whole vehicle, is the vehicle driving resistance torque under the calibrated load condition of the whole vehicle Under this condition, the rotational speed of the transmission shaft is r x , the angular acceleration α x corresponding calibration coefficient; r p and r p+1 are the adjacent calibrated rotational speeds of the transmission shaft rotational speed r x ; α q and α q+1 are the adjacent calibrated angular accelerations of the angular acceleration α x ; and are respectively the vehicle calibrated load condition vehicle driving resistance torques adjacent to .

[0059] In order to accurately collect the angular acceleration and torque change conditions under the conditions of vehicle torsional vibration, impact, etc. and obtain the true load of the vehicle transmission system, in Steps 1 to 8, the signal sampling rates measured by the rotational speed sensor 7 and the wireless torque telemetry system are always greater than or equal to 2000 Hz.

[0060] Embodiment 2

[0061] The transmission shaft calibration bench of this embodiment is the same as that of Embodiment 1. The calibration process method Steps 1 to 7 of this embodiment are the same as those of Embodiment 1. The load of the test vehicle in Step 8 is half load, and the vehicle driving resistance is At the calculation moment, the rotational speed of the transmission shaft is r x , the output voltage signal u of the strain gauge bridge x , the angular acceleration of the transmission shaft Combined with the T o -r-α-S four-dimensional calibration data of the calibrated transmission shaft 4 At the calculation moment, the rotational speed of the transmission shaft is r p <r x <r p+1 , the angular acceleration α q <α x <α q+1 ; r p and r p+1 are the adjacent calibrated rotational speeds of the rotational speed r x at the calculation moment. α q and α q+1 are the adjacent calibrated angular accelerations of the angular acceleration α x at the calculation moment; the torque T of the transmission shaft at the calculation moment x can be calculated according to the following formula:

[0062]

[0063] Embodiment III

[0064] The drive shaft calibration bench of this embodiment is the same as that of Embodiment I. The method steps 1 to 7 of the calibration process in this embodiment are the same as those of Embodiment I. The load of the test vehicle in step 8 is half load, and the vehicle running resistance is Calculate the rotational speed r of the drive shaft 4 at the calculation moment x , the output voltage signal u of the strain gauge bridge x , and the angular acceleration of the drive shaft Combine to calibrate the T of the drive shaft o -r-α-S four-dimensional calibration data Calculate the rotational speed r of the drive shaft at the calculation moment x =r p , the angular acceleration α x =α q ; r p and α q are the calibrated rotational speed and angular acceleration of the drive shaft. The torque T of the drive shaft at the calculation moment x can be calculated according to the following formula:

[0065]

[0066] It should be noted that the above are only three specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art in the technical field of the present invention can easily think of various equivalent modifications or substitutions within the scope of the specific implementation manners disclosed by the present invention, and these modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A transmission shaft calibration bench, characterized in that: It comprises a base (1), a data acquisition system (9), a drive motor (2), a first reducer (3), a second reducer (5) and a load motor (6) arranged on the base (1), and a rotation speed sensor (7) and a wireless torque telemetry system whose output ends are respectively electrically connected to input ends of the data acquisition system (9); The output end of the driving motor (2) is connected to the input end of the first reducer (3) via a first connecting shaft, the output end of the load motor (6) is connected to the input end of the second reducer (5) via a second connecting shaft, and the transmission shaft (4) to be calibrated is installed between the output end of the first reducer (3) and the output end of the second reducer (5); The central axes of the first connecting shaft, the second connecting shaft and the transmission shaft (4) are collinear; The first reducer (3) and the second reducer (5) are used to reduce speed and increase torque of the drive motor (2) and the load motor (6) respectively; the rotation speed sensor (7) is used to test the rotation speed of the transmission shaft (4); the wireless torque telemetry system is used to test the voltage signal generated by the transmission shaft (4) due to the change of loading torque, and comprises a strain gauge bridge attached to the transmission shaft (4) and a wireless transmitting module (82) connected to the output end of the strain gauge bridge, and a wireless receiving module (81) electrically connected to the input end of the data acquisition system (9); the strain gauge bridge comprises a plurality of strain gauges, and the wireless transmitting module (82) is used to transmit the data measured by the strain gauge bridge to the wireless receiving module (81).

2. A method for testing the torque of a transmission shaft during vehicle operation, characterized in that: The following steps are involved: Step 1, assemble the transmission shaft calibration bench described in claim 1, install the transmission shaft (4) to be calibrated between the output ends of the first reducer (3) and the second reducer (5), then install the strain gauge bridge and the wireless transmission module (82) at a preset position on the transmission shaft (4), and start the data acquisition system (9); Step 2, determining a preset rule for applying torque to the drive motor (2) and the load motor (6); The preset rule is implemented using the following formula: Among them, T I is the calibrated torque, whose value is equal to 80% of the maximum designed working torque of the transmission shaft (4); T i is the loading torque of the driving motor (2) during a single calibration, n is the number of segments of the calibration torque, i is the index of each calibration loading torque, i=0, 1, 2...n; is the load torque applied by the load motor (6) during calibration, and its value is equal to the vehicle running resistance torque under the calibration load condition; j is the index of each load condition, j=1,2...m, and m is the number of load conditions required for calibrating the vehicle; Take j = 1; Step 3: Start the drive motor (2) and the load motor (6), and input corresponding loading torque and load torque to the drive motor (2) and the load motor (6) respectively according to preset rules, calibrate the transmission shaft (4), and obtain the curve r of the speed change of the transmission shaft (4) over time. i , the output voltage curve u of the strain bridge i ; Step 4: The speed variation curve r obtained in step 3 i , calculate the angular acceleration curve α of the transmission shaft (4) i , torque-voltage calibration coefficient curve S during a single calibration process i ,in Get a single calibration process r i -α i -S i Correspondence Step 5: Change the loading torque T of the drive motor (2) i According to the method of step 3 and step 4, a total of n+1 groups of different loading torques T are obtained. i r i -α i -S i The corresponding relationship Thus, the three-dimensional calibration data set of the first calibration process r-α-S is obtained Wherein α is the angular acceleration of the transmission shaft (4), r is the rotation speed of the transmission shaft (4) measured by the rotation speed sensor (7), and S is the torque-voltage calibration coefficient of the transmission shaft (4); Step 6: Take j = 2, 3, ... m, and follow the methods of steps 3 to 5 to obtain the three-dimensional calibration data sets of the second, third, ... mth calibration processes r-α-S respectively. Thus, the T of the transmission shaft (4) is obtained o -r-α-S four-dimensional calibration dataset Where T o It is the driving resistance of the vehicle under different load conditions; Step 7: Assemble the calibrated transmission shaft (4) to the vehicle, and then install the strain gauge bridge, wireless torque telemetry system and speed sensor (7) on the assembled transmission shaft (4) to ensure that the transmission shaft speed r can be obtained at any time when the vehicle is running. x And the strain gauge bridge output voltage signal u x ; Step 8: According to r x Calculate the angular acceleration curve α of the transmission shaft (4) x , According to the curve α x , voltage signal u x And the fixed data set obtained in step 6 four-dimensional calibration data set Calculate the output torque T of the transmission shaft (4) at any time x , complete the test.

3. The method for testing the transmission shaft torque during vehicle operation according to claim 2, characterized in that: The sampling rate of the signal measured by the rotation speed sensor (7) and the wireless torque telemetry system is always greater than or equal to 2000 Hz.

4. The method for testing the transmission shaft torque during vehicle operation according to claim 3, characterized in that: Step 3 is as follows: Start calibration, define the clockwise rotation direction of the transmission shaft (4) as the positive direction when looking from the drive motor (2) to the load motor (6), and the speed sensor (7) measures the speed of the transmission shaft (4) as r i , the angular acceleration of the transmission shaft (4) is α i ; First, drive the motor system to input the loading torque T in the positive direction i , load motor (6) system loads load torque in negative direction The transmission shaft (4) reaches the maximum speed of the transmission shaft forward drive designed for the vehicle When the load torque T of the drive motor (2) is removed i , by the load torque To decelerate; When the speed drops to 0, the drive motor (2) inputs a reverse load torque T i , the load motor (6) is loaded with load torque in the positive direction Until the speed of the transmission shaft (4) reaches the maximum negative speed of the transmission shaft designed for the vehicle Then the loading torque T input by the drive motor (2) is removed. i , by the load torque decelerate; stop when the speed of the transmission shaft (4) drops to 0, completing a single calibration; record the speed curve r of the transmission shaft (4) during the single loading process i .

5. The method for testing the transmission shaft torque during vehicle operation according to claim 4, characterized in that: In step 8, the transmission shaft (4) outputs a torque T at any time. x The calculation is done using the following formula: in, is the vehicle driving resistance torque under the actual load condition, Calibrate the vehicle's load condition and vehicle driving resistance moment The transmission shaft speed r x , angular acceleration α x Corresponding calibration coefficient; r p With r p+1 is the transmission shaft speed r x The adjacent calibrated speed; α q With α q+1 is the angular acceleration α x The adjacent calibrated angular acceleration of ; and Respectively The vehicle driving resistance torque of adjacent vehicle calibrated load conditions.

6. The method for testing the transmission shaft torque during vehicle operation according to any one of claims 2 to 5, characterized in that: In step 2, n=5 and m=3; When j=1, the corresponding load condition of the whole vehicle is empty; when j=2, the corresponding load condition of the whole vehicle is half-loaded; when j=3, the corresponding load condition of the whole vehicle is fully loaded.

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