Gear clearance meshing optimization control method for speed reducer of pure electric vehicle

Abstract

The invention discloses an optimal control method for gear clearance engagement of a speed reducer of a pure electric vehicle, which comprises the following steps of: when the speed reducer works, controlling gear clearance fit by judging a torque loading direction and adopting fit torque and dynamic fit time in advance before gear engagement; and within the dynamic fitting time, the gear meshing torque is increased to the fitting torque, and after the dynamic fitting time is over, the torque needed for work of the speed reducer continues to be executed. The method has the advantages that the defects caused by gaps are reduced in an optimal control mode, the fitting torque of the vehicle speed reducer can be calibrated through a diagnostic apparatus by using a calibration quantity, and it is ensured that each trolley has a good NVH state.

Description

Technical Field

[0001] The present invention relates to the field of optimization control of new energy vehicles, and in particular to a method for optimizing the backlash meshing of gears in a pure electric vehicle reducer. Background Art

[0002] Most of the pure electric vehicles on the market use integrated electric drive system assemblies. The multi-in-one is formed by integrating other components on the basis of the three-in-one assembly. Its basis is the three-in-one assembly. The reducer in the three-in-one assembly (permanent magnet synchronous motor, motor controller and reducer) plays an important role in reducing the output speed and increasing the torque. The performance of the reducer directly determines the power, economy and NVH status of the whole vehicle. Among them, the gear clearance directly affects the NVH of the whole vehicle.

[0003] From the structural design of the reducer gear, it is necessary to consider factors such as gear processing and manufacturing, installation method and installation accuracy, gear meshing lubrication, wear, etc. It is necessary to ensure a certain gear clearance. The meshing clearance between gears is generally about 3ml. However, if the gear meshing clearance is too large, in the case of a sudden change in torque or load, it will cause collision between teeth during gear meshing, produce a sense of impact and cause vibration and noise of the entire vehicle, and also aggravate gear wear, reduce transmission accuracy, cause inaccurate transmission, and reduce the service life of the gear.

[0004] Small gear meshing clearance means good torque transmission stability. When torque or load changes suddenly, the impact is small, which is beneficial to the NVH of the whole vehicle. However, the requirements for processing and manufacturing costs and installation accuracy increase dramatically. The increase in costs leads to a decrease in product competitiveness. Without considering design factors, the consistency of gear processing and installation, and the collision and wear between gears as the reducer ages, will lead to an increase in gear meshing clearance, thus affecting the driving experience of the whole vehicle and the service life of the gears.

[0005] In the case of objective existence of gear meshing clearance, optimizing the gear meshing process of the reduction mechanism through control logic to reduce the defects caused by the clearance is a technical path that can be considered, but no relevant technical solution details are disclosed in the prior art. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for optimizing the meshing control of the gear clearance of a pure electric vehicle reducer. The defects caused by the existence of clearance can be reduced by optimizing the control method. The vehicle reducer fitting torque can be calibrated by using a calibration quantity through a diagnostic instrument to ensure that each vehicle has a good NVH state.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows: When the reducer is working, by determining the torque loading direction, the fitting torque and the dynamic fitting time are adopted in advance before gear meshing to control the gear clearance fitting. During the dynamic fitting time, the gear meshing torque is increased to the size of the fitting torque, and after the dynamic fitting time ends, the torque required for the reducer to work is continued to be executed.

[0008] The vehicle is set with a calibration mode. In the calibration mode, calibration parameters input by an external device are received, and the calibration parameters in the vehicle controller are stored or updated. The gear meshing of the reducer is controlled according to the stored or updated calibration parameters.

[0009] In the calibration mode, the diagnostic instrument is connected to the vehicle controller through the gateway. The vehicle controller is connected to the reducer through the motor controller. The diagnostic instrument sends the calibration parameters to the vehicle controller through the gateway. The vehicle controller judges the torque loading direction and confirms the positive and negative of the fitting torque, and sends the confirmed fitting torque to the motor controller. The motor controller executes the fitting torque through the motor to fit the gear clearance in the upcoming transmission direction of the reducer.

[0010] The calibration parameters include the fitting torque and the dynamic fitting time. In the calibration mode, the fitting torque and the dynamic fitting time matching the vehicle are respectively obtained through the calibration method; the dynamic fitting time refers to the time for loading the torque from 0 to the fitting torque.

[0011] In the calibration mode, the calibration of the fitting torque includes:

[0012] Step 1: Power on the vehicle and input the fitting torque through the diagnostic instrument;

[0013] Step 2: Step on the brake and shift the vehicle into D gear or R gear. At this time, the vehicle controller judges whether it is a forward fitting torque or a reverse fitting torque according to the gear information, and sends the forward fitting torque or the reverse fitting torque to the motor controller. The motor controller executes the fitting torque through the motor to fit the gear clearance in the upcoming transmission direction of the reducer;

[0014] Step 3: After releasing the brake, judge whether the calibration of the fitting torque is completed according to whether there is an impact when the vehicle starts.

[0015] Step 3 also includes: when the vehicle impact is felt to be large, reduce the fitting torque and return to Step 1. If the impact is small or within an acceptable range, the calibration of the fitting torque is completed.

[0016] In the calibration mode, the calibration of the dynamic fitting time includes:

[0017] S1. Write the dynamic fitting time through the diagnostic instrument and drive the vehicle to a vehicle speed within the set test speed range;

[0018] S2. Control the vehicle to release the accelerator and step on the accelerator respectively within the test speed measurement range, then feel whether there is an impact on the vehicle, and adjust the dynamic fitting time up or down according to the impact of the vehicle, and return to step S1.

[0019] If it is felt that there is an impact on the vehicle in step S2, the dynamic fitting time is adjusted up, and then return to step S1 to continue execution until the impact is felt to be smaller or the impact meets the requirements, and then the calibration of the dynamic fitting time ends.

[0020] The range of the dynamic fitting time is between 0 - 300 ms.

[0021] Feeling the impact of the vehicle includes detecting the speed fluctuation of the motor through sensing, and judging the size of the impact and whether the impact meets the requirements according to the speed fluctuation.

[0022] The advantages of the present invention are as follows: By optimizing the control method, the defects caused by the existence of gaps are reduced. Through the use of calibration quantities, the fitting torque of the vehicle reducer can be calibrated through a diagnostic instrument, ensuring that each vehicle has a good NVH state.

[0023] Without improving the gear processing and manufacturing process and installation accuracy of the reducer, the impact caused by large gear gaps is effectively eliminated;

[0024] Through optimization control, by controlling the fitting torque and dynamic fitting time, the defects caused by gaps are reduced, the vehicle torque transmission accuracy is improved, and gear wear is slowed down;

[0025] By controlling the gear meshing process through the fitting torque and dynamic fitting time, the impact between gears is reduced, the NVH performance of the whole vehicle is improved, and it has higher comfort performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The following briefly describes the content expressed in each drawing of the present invention specification and the marks in the drawings:

[0027] Figure 1 It is a hardware system architecture diagram related to the optimized control method for the gear gap meshing of the reducer of the present invention;

[0028] Figure 2 It is a schematic diagram of the calibration principle of the fitting torque when starting to move forward of the present invention;

[0029] Figure 3 It is a schematic diagram of the calibration principle of the fitting torque when starting to move backward of the present invention;

[0030] Figure 4 It is a schematic diagram of the calibration principle of calibrating the dynamic fitting time during the tip in / out process of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] The following is a further detailed description of the specific implementation manners of the present invention by describing the optimal embodiments with reference to the accompanying drawings.

[0032] This solution provides a method, calibration and device for optimizing the gear clearance meshing of a pure electric vehicle reducer. It mainly includes: a diagnostic instrument, a vehicle controller, a motor controller, a drive motor, a reducer, a brake, and a shifting mechanism. Its main principle is as follows: Due to processing, installation or wear of the reducer, there is a large gear meshing clearance, and the sudden torque causes gear impact, generating vibration and noise and further wearing the gears. Due to the existence of the clearance between the gears, when the relative speed of the mechanical transmission parts changes, the relative positions between the two rotating parts with backlash, under zero torque working conditions, between the driving part and the driven part in the gear, when the speed of the driving part is greater than the speed of the driven part, the driving part chases the driven part and knocks; when the speed of the driving part is less than the speed of the driven part, the driven part chases the driving part and knocks. Therefore, the existence of this clearance will affect the vehicle's use experience, NVH performance and even the life of the gears. And the gears in the reducer of the vehicle will have this situation due to production work, assembly or wear. This solution makes the following technical improvements for this situation:

[0033] During the operation of the vehicle, when there is a torque requirement, the vehicle controller can obtain the torque requirement according to the user's operation, and then drive the reducer to operate through the vehicle controller, the motor controller and the motor to achieve the loading of the torque requirement, so as to realize the output operation of power.

[0034] When the vehicle controller determines that the reducer torque needs to be executed, it first controls the gear clearance to fit by adopting the fitting torque and the dynamic fitting time in advance before the gear meshing according to the determined torque loading direction, and increases the gear meshing torque to the size of the fitting torque within the dynamic fitting time and then continues to increase the torque to the required torque after the dynamic fitting time ends, that is, raises the working torque of the reducer to the required torque.

[0035] Normally, after the vehicle controller judges or receives the reducer torque execution requirement, it directly loads the required torque to control the meshing between the reducer gears. During this process of loading the required torque, collisions will occur between the gears due to abbreviation. Therefore, in order to reduce such collisions, when the vehicle controller judges that the vehicle has a deceleration torque execution requirement, it first controls the fitting between the reducer gears through the stored fitting torque and the dynamic fitting time. Since the adopted fitting torque and the dynamic fitting time are both pre-calibrated and designed, when controlling the operation of the reducer, the meshing between the gears will not generate collisions under the action of the fitting torque, thus reducing collisions and improving the NVH performance, etc.

[0036] The tooth - sticking torque is the torque that can overcome friction and resistance to eliminate the gear clearance and make the gear surfaces fit together. The dynamic fitting time refers to the time taken to increase the torque from 0 to the fitting torque. By using the dynamic fitting time, the torque applied to the reducer gears is increased from 0 to the fitting torque, thus ensuring that no collision occurs due to the clearance.

[0037] When the reducer is working, by determining the torque loading direction in advance, the small torque is applied to make the gear clearance fit. At this time, the clearance has been fitted, and the sudden change in torque will no longer cause gear impact. The gear clearances of each reducer are different, and there are also differences in installation. The fitting torques are different. Using the calibrated value, the fitting torque of the vehicle reducer can be calibrated through a diagnostic instrument to ensure that each vehicle has a good NVH state. When the reducer is working, first, the torque of the reducer gears is increased from 0 to the fitting torque within the dynamic fitting time, and then the torque of the gears is increased to the torque required for the reducer operation according to the torque required for the reducer operation. Since the gear fitting is controlled by a fitting torque first, when the torque required for the reducer operation is executed, no collision will occur due to the lack of any torque between the two gears.

[0038] The pre - calibrated fitting torque and dynamic fitting time are both stored in the vehicle controller. The vehicle controller reads the stored fitting torque and dynamic fitting time to control the fitting of the reducer gears. Since the fitting torque and dynamic fitting time need to be updated and calibrated at regular intervals, the following calibration method is provided in this solution:

[0039] After the vehicle is powered on, enter the reducer fitting torque calibration mode through a diagnostic instrument, and calibrate the fitting torque and dynamic fitting time under the conditions of starting forward, starting backward, and dynamic tip - in / out working conditions respectively. The diagnostic instrument sends the calibration parameters (fitting torque and dynamic fitting time) to the vehicle controller through the gateway. The vehicle controller judges the torque loading direction required for the next step, confirms the positive and negative of the fitting torque, and sends the confirmed fitting torque to the motor controller. The motor controller executes the fitting torque through the motor to fit the gear clearance in the transmission direction of the reducer.

[0040] Since when the torque required for the reducer operation is executed, the gear fitting is pre - controlled by the fitting torque, and the fitting torque is pre - loaded between the gears. When the fitting torque is loaded on the gears, if the torque loading is too fast, it will also cause an impact. Slowing down the torque loading gradient will effectively reduce the sense of impact. For example, the impact of the gear hitting when loading from 0 to the tooth - sticking torque in 1ms is significantly different from that in 100ms. Therefore, the dynamic fitting time refers to the time from 0 to the tooth - sticking torque. By adjusting the fitting torque and dynamic fitting time, the problem of reducing collisions can be achieved.

[0041] When executing the fitting torque, the vehicle control unit determines the torque loading direction and confirms the positive or negative of the fitting torque based on the calibrated parameters stored in advance in the vehicle control unit: the fitting torque and the dynamic fitting time. Then, the vehicle control unit sends the confirmed fitting torque and the dynamic fitting time to the motor control unit. The motor control unit executes the fitting torque through the motor to fit the gear clearance in the upcoming transmission direction of the reducer, that is, the motor controls the torque between the reducer gears to be loaded to the fitting torque to achieve gear clearance fitting. The motor torque is transmitted through the output shaft, and the same applies to the reducer. The teeth are on the shaft or the gears and the shaft are rigidly connected, and the tooth meshing is carried out simultaneously. If the torque direction remains unchanged, the teeth will remain in the meshing state once they are meshed. Therefore, each time the working demand torque of the reducer is detected, the fitting torque can be loaded once to achieve the purpose.

[0042] Since the gear wear and others are different every once in a while, it is necessary to calibrate the calibrated parameters. The vehicle control unit is provided with a calibration mode. In the calibration mode, the vehicle control unit can receive the calibrated parameters written by external devices. In the diagnostic mode, the diagnostic instrument is connected to the vehicle control unit through the gateway to write the calibrated parameters, so as to update the calibrated report parameters. In order to determine whether the written parameters meet the requirements, the written calibrated parameters can be tested. The parameter test calibration steps include:

[0043] I. Starting forward calibration steps:

[0044] 1. Power on the vehicle and enter the reducer fitting torque calibration mode through the diagnostic instrument;

[0045] 2. The calibration personnel write the fitting torque in the fitting torque calibration mode and transmit it to the vehicle control unit;

[0046] 3. The calibration personnel step on the brake and shift to D gear;

[0047] 4. The diagnostic instrument sends the calibrated parameters to the vehicle control unit through the gateway. The vehicle control unit gives the forward fitting torque according to the gear signal and sends it to the motor control unit.

[0048] 5. The motor control unit executes the fitting torque through the motor to fit the gear clearance in the upcoming transmission direction of the reducer;

[0049] 6. Release the brake and start moving forward, and feel whether there is an impact when starting;

[0050] If there is an impact, adjust the size of the written fitting torque, and then repeat steps 2 to 6 until there is no impact, and at this time the fitting torque meets the fitting torque corresponding to starting forward.

[0051] I. Starting backward calibration steps:

[0052] 1. Power on the vehicle and write the fitting torque into the vehicle controller through a diagnostic instrument. At this time, enter the reduction gear fitting torque calibration mode; when performing the first test, write the fitting torque that meets the requirements for starting and moving forward obtained in step 6 of starting and moving forward into the vehicle controller.

[0053] 2. The calibration personnel write and set the fitting torque in the fitting torque calibration mode and transmit it to the vehicle controller.

[0054] 3. The calibration personnel step on the brake and shift to reverse gear.

[0055] 4. The diagnostic instrument sends the calibration parameters to the vehicle controller through the gateway. The vehicle controller gives the reverse fitting torque according to the gear signal and sends it to the motor controller.

[0056] 5. The motor controller executes the fitting torque through the motor to fit the gear clearance in the upcoming transmission direction of the reduction gear.

[0057] 6. Release the brake and start moving backward, and feel whether there is an impact when starting.

[0058] If there is an impact, adjust the size of the written fitting torque, and then repeat steps 2 to 6 until there is no impact, and at this time the fitting torque meets the fitting torque corresponding to starting and moving forward.

[0059] Whether there is an impact can be judged by the experience of the calibration personnel or by collecting through quantitative sensors. Detect the magnitude of the motor speed fluctuation through a speed sensor, encoder, etc., and judge whether there is an impact according to the magnitude of the speed fluctuation. Judge the vehicle impact by calibrating the threshold value of the speed fluctuation evaluation through experience. For example, when the speed fluctuation is more than 100 revolutions, the impact feeling is obvious, and when it is less than 100 revolutions, the human feeling is acceptable. The magnitude of the speed fluctuation can be defined as 100 revolutions or a suitable value below 100 revolutions as the speed fluctuation threshold, and then judge whether there is an impact according to the collected magnitude of the speed fluctuation. If it is greater than the speed fluctuation threshold, it is judged that there is an impact, otherwise it is judged that there is no impact.

[0060] When performing the calibration test steps of starting and moving forward or starting and moving backward, when it is judged that there is an impact, reduce the fitting torque and return to steps 2 - 6. When it is judged that there is no impact, the fitting torque written into the vehicle controller at this time is the fitting torque that meets the requirements.

[0061] After the verification of the fitting torque parameters for the starting and moving backward working condition is okay, the diagnostic instrument writes the dynamic fitting time parameter. The general time upper limit of the dynamic fitting time is 300 ms. Drive the vehicle to a certain speed and test and calibrate the dynamic fitting time under the tip in / out working condition.

[0062] Drive the vehicle to the set test speed range, then step on and release the accelerator pedal respectively, and feel whether there is an impact under the conditions of stepping on and releasing the accelerator. If there is no impact under the tip in / out condition, the dynamic fitting time written in the vehicle controller at this time meets the requirements; otherwise, increase the dynamic fitting time, accelerate the vehicle speed to the set test speed range and then continue the tip in and tip out operations to determine whether there is an impact. If there is an impact, continue to modify the dynamic fitting time until there is no impact, and the dynamic fitting time at this time is the time that meets the requirements. When there is an impact, increase the dynamic fitting time parameter, write the adjusted time parameter back into the vehicle controller and continue the test.

[0063] Judge whether there is an impact under the tip in / out condition and confirm the dynamic fitting time; the motor speed fluctuation can be used to evaluate whether there is an impact. Add a time parameter on the basis of the tooth meshing torque, and the requirement for the size of the speed fluctuation is stricter than that with only the tooth meshing torque.

[0064] The meshing torque and dynamic fitting time obtained through the above test and calibration are used as the calibration parameters that meet the requirements. Write the meshing torque and dynamic fitting time into the vehicle controller. When the reduction gear works each time, the vehicle controller executes the torque and time, which can meet the optimization of the gear clearance. After obtaining the calibration parameters that meet the requirements, the calibration ends and the optimization is completed.

[0065] As Figure 1 shown, the system architecture diagram of gear clearance meshing optimization:

[0066] A method, calibration and device for optimizing the meshing of gear clearances of a pure electric vehicle reducer mainly consists of a diagnostic instrument, a vehicle controller, a motor controller, a drive motor, a reducer, a brake, a shift mechanism, etc. The diagnostic instrument is used to start the calibration mode, calibrate the meshing torque / dynamic fitting time parameters, and write the calibration parameters into the vehicle controller; the gateway is used to forward the diagnostic instrument information to the vehicle controller; the vehicle controller judges the torque execution direction according to the gear position signal and the brake signal, and sends the meshing torque instruction to the motor controller. The motor controller and the motor execute the meshing torque to fit the gear clearance of the reducer.

[0067] As Figure 2 shown, the schematic diagram of static start meshing torque loading:

[0068] When the vehicle is powered on and the brake is depressed and the forward gear is engaged, the vehicle controller sends the positive meshing torque to the motor controller. The motor controller and the motor execute the positive meshing torque to fit the gear meshing clearance. After the gear meshing clearance is fitted, this positive meshing torque is maintained until the driver releases the brake to start. When the vehicle controller judges that the driver's required torque is greater than the meshing torque, it sends the driver's required torque to the motor controller for execution, and the motor responds to the driver's required torque.

[0069] When the vehicle is powered on and the reverse gear is engaged while stepping on the brake, the vehicle control unit sends the negative latching torque to the motor control unit. The motor control unit and the motor execute the negative latching torque. After the meshing clearance of the latching gear is latched, this negative latching torque is maintained until the driver releases the brake to reverse. When the vehicle control unit determines that the driver's required torque is greater than the latching torque, it sends the driver's required torque to the motor control unit for execution, and the motor responds to the driver's required torque.

[0070] As Figure 3 shown, the schematic diagram of latching torque / latching time under dynamic tip out condition:

[0071] During driving, when the driver releases the accelerator (tip out), the torque switches from positive torque to negative torque. When the negative torque is switched, the direction of the force is reversed, and the mating surface of the gear also needs to be reversed. The vehicle control unit sends a negative latching torque to the motor control unit and maintains the negative latching torque for a period of time to ensure that the meshing clearance of the gear is fully latched. After the meshing clearance of the gear is fully latched, the energy recovery mode is entered. When the accelerator is pressed again (tip in), the torque switches from negative torque to positive torque, and the direction of the force is reversed again. The vehicle control unit sends a positive latching torque to the motor control unit and maintains the positive latching torque for a period of time to ensure that the meshing clearance of the gear is fully latched. After the meshing clearance of the gear is fully latched, the vehicle responds to the driver's accelerator torque request.

[0072] As Figure 4 shown, the flow chart of the gear clearance meshing optimization system:

[0073] The main steps are as follows:

[0074] 1. Power on the vehicle, and the driver engages the gear to start or releases / presses the accelerator;

[0075] 2. The vehicle control unit determines the direction of the latching torque required and sends the latching torque command to the motor control unit;

[0076] 3. The drive system executes the latching torque command to latch the meshing clearance of the reduction gear;

[0077] 4. When static, the latching torque is maintained until the driver's accelerator request is greater than the latching torque, and the vehicle control unit commands the drive system to respond to the driver's accelerator torque request; when dynamic (tip in / out), it is maintained until the dynamic latching time, and then the energy recovery or the driver's accelerator torque request is normally executed.

[0078] Obviously, the specific implementation of the present invention is not limited by the above methods. As long as various non-substantial improvements are made by adopting the method concept and technical solution of the present invention, they are all within the protection scope of the present invention.

Claims

1. An optimized control method for the gear clearance meshing of a pure electric vehicle reducer, characterized in that: When the reducer is working, by determining the torque loading direction, the fitting torque and the dynamic fitting time are adopted in advance before gear meshing to control the gear clearance fitting. During the dynamic fitting time, the gear meshing torque is increased to the magnitude of the fitting torque, and after the dynamic fitting time ends, the torque required for the reducer to work is continued to be executed.

2. The optimized control method for the gear clearance meshing of a pure electric vehicle reducer according to claim 1, wherein: The whole vehicle is set with a calibration mode. In the calibration mode, the calibration parameters input by an external device are received, stored or updated in the vehicle controller, and the gear meshing of the reducer is controlled according to the stored or updated calibration parameters.

3. A method for optimizing the meshing control of gear clearance in a pure electric vehicle reducer according to claim 2, characterized in that: In the calibration mode, the diagnostic instrument is connected to the vehicle controller through the gateway. The vehicle controller is connected to the reducer through the motor controller. The diagnostic instrument sends the calibration parameters to the vehicle controller through the gateway. The vehicle controller judges the torque loading direction and confirms the positive or negative of the fitting torque, and sends the confirmed fitting torque to the motor controller. The motor controller executes the fitting torque through the motor to fit the gear clearance in the upcoming transmission direction of the reducer.

4. A method for optimizing the meshing control of the gear clearance of a pure electric vehicle reducer according to any one of claims 1-3, characterized in that: The calibration parameters include the fitting torque and the dynamic fitting time. In the calibration mode, the fitting torque and the dynamic fitting time matching the vehicle are respectively obtained through the calibration method; the dynamic fitting time refers to the time for loading the torque from 0 to the fitting torque.

5. A method for optimizing the control of gear clearance meshing of a pure electric vehicle reducer as claimed in claim 4, characterized in that: In the calibration mode, the calibration of the fitting torque includes: Step 1: Power on the vehicle and input the fitting torque through the diagnostic instrument; Step 2: Step on the brake and shift the vehicle into D gear or R gear. At this time, the vehicle controller judges whether it is a positive fitting torque or a negative fitting torque according to the gear information, and sends the positive fitting torque or the negative fitting torque to the motor controller. The motor controller executes the fitting torque through the motor to fit the gear clearance in the upcoming transmission direction of the reducer; Step 3: After releasing the brake, judge whether the calibration of the fitting torque is completed according to whether there is an impact when the vehicle starts.

6. A method for optimizing the control of gear clearance meshing of a pure electric vehicle reducer as claimed in claim 5, characterized in that: Step 3 further includes: when the vehicle impact is felt to be large, reduce the fitting torque and return to Step 1. If the impact is small or within an acceptable range, the calibration of the fitting torque is completed.

7. A method for optimizing the meshing control of gear clearances in a pure electric vehicle reducer according to claim 5 or 6, characterized in that: In the calibration mode, the calibration of the dynamic fitting time includes: S1. Write the dynamic fitting time through the diagnostic instrument and drive the vehicle to a speed within the set test speed range; S2. In the test speed range, respectively control the vehicle to release the accelerator and step on the accelerator, and then feel whether there is an impact on the vehicle. Adjust the dynamic fitting time up or down according to the impact of the vehicle and return to Step S1.

8. A method for optimizing the meshing control of the gear clearance of a pure electric vehicle reducer according to claim 7, characterized in that: In Step S2, if an impact on the vehicle is felt, the dynamic fitting time is increased, and then return to Step S1 to continue to execute until the impact is felt to be small or the impact meets the requirements, and then the calibration of the dynamic fitting time ends.

9. A method for optimizing the meshing control of the gear clearance of a pure electric vehicle reducer according to claim 7 or 8, characterized in that: The range of the dynamic fitting time is between 0 - 300 ms.

10. A method for optimizing the control of gear clearance meshing of a pure electric vehicle reducer as claimed in claim 5 or 7, characterized in that: Feeling the impact of the vehicle includes detecting the motor speed fluctuation through sensing, and judging the magnitude of the impact and whether the impact meets the requirements based on the speed fluctuation.

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