Gear shifting process control method for synchronizer-free motor direct drive type automatic transmission

Abstract

The invention relates to a control method for the gear shifting process of a synchronizer-free motor direct drive type automatic transmission, belongs to the technical field of automobile automatic transmission control, and is applied to a gear and gear sleeve meshing structure with long and short teeth distributed at intervals. The method comprises the steps that the gear shifting process is divided into four stages, namely the stage from torque reduction to neutral gear shifting, the stage from motor speed regulation to gear shifting idle stroke elimination, the stage from gear entering to speed change tooth alignment synchronization and the stage from complete gear entering to torque increasing; in each stage of a gear shifting process, current state information of a whole vehicle and a gearbox and related sensor information are collected; the state information and the sensor information comprise the position of an accelerator pedal, the position of a brake stroke, the actual torque of a driving motor, the gear shifting position of a gear shifting sensor of each gear, the value of a gradient sensor, the current of the gear shifting motor, the rotating speed of the driving motor, the current gear, the target gear, the rotating speed of an output shaft and the gear shifting process state so as to control the gear shifting process.

Description

Technical Field

[0001] The present application relates to the technical field of automobile automatic transmission control, and in particular to a method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor. Background Art

[0002] In recent years, with the continuous updating and upgrading of technology, the automobile industry has ushered in vigorous vitality, and new technologies have emerged in an endless stream. Especially for the commercial vehicle industry, it has been further developed. In the field of commercial vehicle mining trucks, due to the particularity of its work, there are great differences in the requirements for transmissions compared to traditional light and heavy trucks. Mining trucks are often in working conditions such as low speed, heavy load and bumps, so the transmission efficiency and transmission torque of the transmission system are relatively high. With the innovation of electric drive technology, electric mining trucks have gradually become mainstream, and synchronizer-free motor direct-drive automatic transmissions have slowly entered people's field of vision. Due to the particularity of its structure, the gear shifting control process of the transmission has been studied by many scholars and institutions.

[0003] At present, for direct-drive automatic transmissions without synchronizers, the shift control process is basically to reduce torque first, then shift to neutral, then adjust speed, then shift into gear, and finally increase torque. For each specific process, the control method varies from person to person. Regardless of the control method, the ultimate control goal is to make the shifting smooth and impact-free, with a short power interruption time and a high success rate for shifting. Many current control methods are still lacking in shortening the shifting time, reducing the shifting shock, and increasing the success rate for shifting. The existing gear sleeve meshing structure with long and short teeth can reduce the impact noise of spur teeth to a certain extent. Coupled with the guiding role of the long teeth, the driver feels softer and smoother.

[0004] Based on the gear sleeve meshing structure with a long and short tooth distribution method, this application proposes a new shifting process control strategy, which can, to a certain extent, make the shifting smoother, improve the impact, shorten the power interruption time, increase the success rate of shifting, and make the control system more adaptable and robust. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present application provides a method for controlling the gear shifting process of a direct-drive automatic transmission without a synchronizer motor, aiming to provide a method for controlling the gear shifting process with smoother gear shifting, improved gear shifting shock, and shortened gear shifting time.

[0006] To achieve the above-mentioned purpose, the present application provides a method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor, which is applied to a gear sleeve meshing structure with a long-short tooth arrangement, and the method comprises:

[0007] The gear shifting process is divided into four stages: torque reduction to neutral gear stage, motor speed regulation to eliminate gear idle travel stage, gear shifting to gear shifting synchronization stage, and complete gear shifting to torque increase stage.

[0008] At each stage of the shifting process, the current vehicle and gearbox status information and related sensor information are collected, including: accelerator pedal position, brake travel position, actual torque of the drive motor, shift position of each gear shift sensor, slope sensor value, shift motor current, drive motor speed, current gear, target gear, output shaft speed and shifting process status, so as to control the shifting process; among which,

[0009] In the torque reduction to neutral gear shifting stage, the gear shifting is performed according to the actual torque change combined with the estimated time feedforward, open-closed loop joint control and different working conditions;

[0010] In the stage of motor speed regulation to eliminate the idle travel in gear, dynamic target speed rate and dynamic target speed are used, combined with the target speed crossing speed regulation method to perform speed control, and a cascade speed rate with a speed rate feedforward gain and a speed controller are used to adjust the speed rate and speed to synchronize the speed and speed.

[0011] Optionally, before the torque reduction to neutral gear shifting stage, the method further includes:

[0012] S10: monitoring the state of the gear shifting process, and if the gear shifting starts, recording the gear shifting start torque, and obtaining the basic target speed of the drive motor according to the current gear position, the target gear position, and the output shaft speed;

[0013] S20: determining a torque reduction rate according to the current driving motor speed, the actual driving motor torque, the throttle level, and the braking stroke;

[0014] S30: Calculating an estimated torque reduction time based on the torque reduction rate.

[0015] Optionally, in the torque reduction to neutral gear shifting stage, shifting the gear according to actual torque change combined with estimated time feedforward, open-closed loop joint control and different working conditions includes:

[0016] S40: The first stage of neutral shifting, from the start of the shifting to when the actual torque is greater than or equal to 2 / 3 of the shifting start torque, the shifting motor uses an open-loop duty cycle to intermittently shift the gears, while monitoring the current size and actual torque of the shifting motor;

[0017] S50: In the second stage of neutral shifting, when the actual torque is within the range of 1 / 3 to 2 / 3 of the shift start torque, the shift position sensor value and the actual torque are collected, the torque reduction rate is calculated, and the shift position sensor change rate is kept constant to shift the gear. The output duty cycle of the shift motor is adjusted in real time by adopting a closed-loop control method with the constant shift position sensor change rate as the control target;

[0018] S60: In the third stage of neutral gear shifting, when the actual torque is less than 1 / 3 of the shift start torque, the shift position sensor value and the actual torque value of the drive motor are collected, and the shift motor duty cycle is output by position closed-loop control with the neutral position as the target.

[0019] Optionally, before the motor speed is adjusted to eliminate the idle travel stage of gear engagement, the method further includes:

[0020] A1: Determine whether the current gear and the target gear share a shift actuator;

[0021] A2: If a shift actuator is shared, it is determined whether the actual position of the gear shift is within the range of the lower limit top gear position and the upper limit top gear position; if the actual position of the gear shift is within the range of the lower limit top gear position and the upper limit top gear position, the torque reduction to neutral shifting stage is completed;

[0022] A3: If a shift actuator is not shared, determine whether the shift position is within the neutral center position threshold; if the shift position is within the neutral center position threshold, the torque reduction to neutral shift phase ends, and enter the motor speed regulation to eliminate the gear idle stroke phase; if the shift position is not within the neutral center position threshold, continue to execute A1, A2, A3 until the shift position is within the neutral center position threshold.

[0023] Optionally, in the stage of regulating the motor speed to eliminate the idle stroke in gear, a dynamic target speed rate and a dynamic target speed are used, and a speed regulation mode of crossing the target speed is combined to perform speed regulation control, and a cascade speed rate with a speed rate feedforward gain and a speed controller are used to adjust the speed rate and the speed for speed and speed synchronization, including the speed regulation stage:

[0024] S71: The speed and speed synchronization preparation stage uses dynamic target speed and proportional parameters for control;

[0025] S72: In the speed and rotational speed synchronization stage, a dynamic target rotational speed and a dynamic target rotational speed are adopted, and a cascaded rotational speed with a rotational speed feedforward gain and a rotational speed controller are used to adjust the rotational speed and the rotational speed for speed synchronization.

[0026] Optionally, in the stage of adjusting the speed of the motor to eliminate the idle travel when the gear is engaged, the method further comprises a stage of eliminating the axial idle travel when the gear is engaged:

[0027] S73: adopts nonlinear single class proportional parameter control;

[0028] S74: adopts a periodic constant duty cycle, fixed time period, intermittent movement conservative control method, including a shift head retraction process; wherein, the shift head retraction process is: if the S71 and the S72 of the speed regulation stage are completed before or at the same time as this stage, then directly enter the gear shift to gear synchronization stage, otherwise after the gear engagement axial position reaches the set point, a small amplitude set stroke retraction is performed to retract the set stroke.

[0029] Optionally, during the gear shifting to gear-shifting synchronization stage, the method includes:

[0030] S81: A three-loop control method of position, speed and acceleration is adopted to follow the set gear-entry curve by taking into account the gravity acceleration component feedforward that changes with the slope. If the gear hits the top gear, the shift position is retreated to the neutral direction by a set distance and then continues to follow the set gear-entry curve to engage the gear;

[0031] S82: After the gear shift position reaches the end position area of ​​the gear shifting to gear shifting synchronization stage, the speed of the drive motor is adjusted to form a speed rate difference between the gear and the gear sleeve to complete the gear alignment and eliminate the circumferential gap between the teeth; wherein, the method of adjusting the speed of the drive motor includes: constructing an optimal target speed rate function based on the elastic collision theory of classical mechanics and the physical difference of the gap between the gear sleeves.

[0032] Optionally, before the complete gear shifting to the torque increasing stage, the method further comprises:

[0033] If the gear shifting gear synchronization termination condition is met, it is determined that the gear shifting gear synchronization phase is terminated, and the phase of fully gear shifting gear synchronization is entered. The gear shifting gear synchronization termination condition is:

[0034]

[0035] in, is the relative rotation arc length of the gear sleeve in the circumferential direction, is the driving motor torque, The minimum torque required to drive the motor is n Mot_Act (t) is the current driving motor speed, n DM_B (t) is the speed value of the driving motor, Δn Set The speed reaches the target value judgment threshold, Δn Mot_Act (t) is the current driving motor speed, Δn Rate The driving motor torque is , the target gear is gear i, and the speed rate when the automatic transmission output end has no load, is the calibration adjustment factor.

[0036] Optionally, during the full gear-into-torque increase phase, the method includes:

[0037] Adopting semi-closed loop control mode, the gear is shifted by driving torque adjustment;

[0038] When shifting into a gear, torque is increased based on the gear shift position curve to restore the torque. When the gear shift position reaches the set position range, the shift knob retreats a set distance in the neutral direction, and then the torque is restored to the required torque. When restoring the torque to the required torque, the restored torque value is adjusted based on the load characteristics of the gear shift actuator.

[0039] Optionally, the shifting in a driving torque adjustment manner includes: setting a shifting and retracting position following curve; constructing a physical relationship between a shifting motor and a shifting position based on a ball screw structure; and outputting a constant duty cycle of the shifting motor;

[0040] The torque increase based on the shift position curve to restore the torque also includes: constructing the relationship between the load characteristics of the shift motor of the ball screw structure and the driving torque; setting the position curve according to the relationship between the load characteristics of the shift motor and the driving torque, as well as the torque, voltage and motion characteristics of the DC brush motor, so that the driving motor torque gradually increases with the shift position.

[0041] The present application provides a method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer, which is applied to a gear sleeve meshing structure with a long and short tooth arrangement. The method comprises: dividing the shifting process into four stages: a stage of reducing torque to disengaging the neutral gear, a stage of regulating the motor speed to eliminating the idle travel of the gear, a stage of shifting into gear to synchronizing the gears, and a stage of fully shifting into gear to increasing the torque; at each stage of the shifting process, the current status information of the vehicle and the transmission and the relevant sensor information are collected, and the status information and the sensor information include: the position of the accelerator pedal, the brake travel position, the actual torque of the drive motor, the shift position of each gear shift sensor, The slope sensor value, shift motor current, drive motor speed, current gear, target gear, output shaft speed and shift process status are used to control the shift process; wherein, in the torque reduction to neutral gear stage, the gear is disengaged according to the actual torque change combined with estimated time feedforward, open-closed loop joint control and divided working conditions; in the motor speed regulation to eliminate the gear idle stroke stage, the dynamic target speed rate and dynamic target speed are used, combined with the crossing target speed regulation method for speed control, and the cascade speed rate with speed rate feedforward gain and the speed controller are used to adjust the speed rate and speed for speed and speed synchronization.

[0042] The present application provides a method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor. Based on the powertrain of the direct-drive automatic transmission without a synchronizer motor, the characteristics of the direct drive of the motor and the mechanical structure of the transmission shifting, the entire shifting position movement process is included in the torque reduction, speed regulation and torque increase process of the drive motor based on theoretical calculations and experience, thereby shortening the transmission shifting time. The present application also adopts a gear sleeve meshing structure with a long and short tooth spacing, combined with a target speed regulation method, and adopts a dynamic target speed rate and a dynamic target speed. The cascade speed rate and speed controller with a speed rate feedforward gain are used to adjust the speed rate and speed, thereby improving the problem of shifting shock caused by excessive speed difference or speed change rate at the moment of gear sleeve meshing, and because the long and short tooth spacing in the meshing stage reduces the probability of top teeth, the success rate of gear engagement is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is one of the flow charts of an embodiment of a method for controlling a shifting process of a direct-drive automatic transmission without a synchronizer motor of the present application;

[0044] Figure 2 This is a second flow chart of an embodiment of a method for controlling a shifting process of a direct-drive automatic transmission without a synchronizer motor of the present application;

[0045] Figure 3 This is a flowchart of a third embodiment of a method for controlling a shifting process of a direct-drive automatic transmission without a synchronizer motor according to the present application;

[0046] Figure 4 This is a schematic diagram of a state determination process flow of a torque reduction to neutral shifting process according to an embodiment of a method for controlling a shifting process of a direct-drive automatic transmission without a synchronizer motor of the present application;

[0047] Figure 5 This is a schematic diagram of a shift control process of a direct-drive automatic transmission without a synchronizer motor according to an embodiment of the present invention;

[0048] Figure 6 This is a schematic diagram of the gear sleeve meshing structure of an embodiment of a method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor in the present application. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0050] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0051] In recent years, with the continuous updating and upgrading of technology, the automobile industry has ushered in vigorous vitality, and new technologies have emerged in an endless stream. Especially for the commercial vehicle industry, it has been further developed. In the field of commercial vehicle mining trucks, due to the particularity of its work, there are great differences in the requirements for transmissions compared to traditional light and heavy trucks. Mining trucks are often in working conditions such as low speed, heavy load and bumps, so the transmission efficiency and transmission torque of the transmission system are relatively high. With the innovation of electric drive technology, electric mining trucks have gradually become mainstream, and synchronizer-free motor direct-drive automatic transmissions have slowly entered people's field of vision. Due to the particularity of its structure, the gear shifting control process of the transmission has been studied by many scholars and institutions.

[0052] At present, for the direct-drive automatic transmission without synchronizer, the shift control process is basically to reduce torque first, then disengage neutral gear, then adjust speed, then engage gear, and finally increase torque. For each specific process, the control method varies from person to person. Regardless of the control method, the ultimate control goal is to make the gear engagement smooth and without impact, with a short power interruption time and a high gear engagement success rate. Many current control methods are still lacking in shortening the gear shift time, reducing the gear shift impact, and improving the gear engagement success rate. Based on this, the present application proposes a new gear shift process control strategy, which, to a certain extent, can make the gear shift smoother, improve the impact, shorten the power interruption time, improve the gear engagement success rate, and make the control system more adaptable and robust.

[0053] Based on the above-mentioned overall concept of the shifting process control method of a direct-driven automatic transmission without a synchronizer motor of the present application, various embodiments of the shifting process control method of a direct-driven automatic transmission without a synchronizer motor of the present application are proposed.

[0054] The present application is based on a direct-drive automatic transmission without a synchronizer motor, and is applied to a gear sleeve meshing structure with a long and short tooth arrangement. By changing the meshing structure of the combined gear and the sleeve, the shifting process is merged and subdivided into four stages: the torque reduction to neutral gear stage, the motor speed adjustment to eliminate the idle travel stage, the gear shifting to gear synchronization stage, and the full gear shifting to torque increase stage. At each stage of the shifting process, the current status of the vehicle and the gearbox and related sensor information are collected, mainly including: accelerator pedal position, brake travel position, actual torque of the drive motor, position of each gear shift sensor, slope sensor value, shift motor current, drive motor speed, current gear, target gear, output shaft speed and shifting process status, so as to control the shifting process.

[0055] Among them, in the torque reduction to neutral gear stage, the gear is disengaged according to the actual torque change combined with the estimated time feedforward, open-closed loop joint control and divided working conditions; in the motor speed regulation to eliminate the gear neutral stroke stage, the dynamic target speed rate and dynamic target speed are adopted, combined with the crossing target speed regulation method for speed control, and the cascade speed rate with speed rate feedforward gain and the speed controller are used to adjust the speed rate and speed for speed and speed synchronization.

[0056] The flowchart of the control method for the shifting process of the direct-drive automatic transmission without a synchronizer motor in this application is specifically referred to Figures 1 to 3 .

[0057] In this embodiment, the present application provides a method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor. Based on the powertrain of the direct-drive automatic transmission without a synchronizer motor, based on the characteristics of the motor direct drive and the mechanical structure of the transmission shifting, based on theoretical calculations and experience, the entire shifting position movement process is included in the torque reduction, speed regulation and torque increase process of the drive motor, thereby shortening the transmission shifting time. The present application also adopts a gear sleeve meshing structure with a long and short tooth spacing, combined with a target speed regulation method, and adopts a dynamic target speed rate and a dynamic target speed. The cascade speed rate and speed controller with a speed rate feedforward gain are used to adjust the speed rate and speed, thereby improving the problem of shifting shock caused by excessive speed difference or speed change rate at the moment of gear sleeve meshing, and because the long and short tooth spacing in the meshing stage reduces the probability of top teeth, the success rate of gear engagement is improved.

[0058] Furthermore, based on the above-mentioned first embodiment of the shifting process control method of a direct-drive automatic transmission without a synchronizer motor of the present application, a second embodiment of the shifting process control method of a direct-drive automatic transmission without a synchronizer motor of the present application is proposed.

[0059] In the second embodiment of the control method for the shifting process of a direct-drive automatic transmission without a synchronizer motor of the present application, before the torque reduction to neutral gear shifting stage, the method further includes:

[0060] Step S10, monitoring the state of the gear shift process, if the gear shift starts, recording the actual torque of the drive motor at this time as the gear shift start torque T Start , and based on the collected current gear, target gear and output shaft speed, calculate the basic target speed of the drive motor as shown below:

[0061]

[0062] In the above formula, n DM_B (t) is the basic target speed of the driving motor, is the target gear ratio, n os(t) is the current output shaft speed.

[0063] Step S20: Determine the torque reduction rate Rate based on the current drive motor speed, actual drive motor torque, throttle size, and brake stroke size. Dectq (t), as follows:

[0064]

[0065] Among them, Rate M_maxLim is the maximum change rate of the torque of the driving motor. If the torque change rate exceeds the maximum change rate of the torque of the driving motor, an overcurrent will occur. max is the peak torque of the driving motor, T Act (t) is the actual torque of the driving motor, is a positive minimum, n Mot_Act (t) is the current driving motor speed, n mot_maxLim is the maximum speed of the drive motor, and Rate1, Rate2, Rate3, and Rate4 are actual vehicle calibration parameters, i.e., the torque change within a cycle of 10ms, and the actual vehicle calibration parameters are not greater than Rate M_maxLim .

[0066] Step S30, based on the calculated torque reduction rate Rate Dectq (t), calculate the expected torque reduction time in real time, the calculation method is as follows:

[0067] TM Total (t) is the estimated torque reduction time.

[0068] Reference Figure 1 , Figure 1 This is one of the flow charts of an embodiment of a method for controlling a shifting process of a direct-drive automatic transmission without a synchronizer motor.

[0069] Further, based on the first embodiment and / or the second embodiment of the shifting process control method of the direct-drive automatic transmission without a synchronizer motor of the present application, a third embodiment of the shifting process control method of the direct-drive automatic transmission without a synchronizer motor of the present application is proposed. In this embodiment, in the torque reduction to neutral shifting stage, the gear is shifted according to the actual torque change combined with the estimated time feedforward, open-closed loop joint control and divided working conditions, which may specifically include:

[0070] Step S40, when the gear shift starts until the actual torque is greater than or equal to Shift start torque, this is the first stage of neutral shifting. Since the torque of the drive motor is large at this time, the inner tooth surface of the gear sleeve fits closely with the meshing tooth surface, and the static friction is large, the shift motor uses an open-loop duty cycle to intermittently shift gears in the initial stage, and monitors the current size and actual torque size of the shift motor at the same time, as follows:

[0071]

[0072] Among them, SM Current is the actual current of the shift motor, SM CurrentLim To safely limit the current of the shift motor, TM Count The duration of high current of the shift motor, TM Set The time limit for the continuous high current of the shift motor, D Idle is the starting duty cycle of the shift actuator when it is stationary, ΔSP is the rate of change of the shift position sensor within 10ms, and ΔSP min To determine the rate of change of the sensor value when the shift actuator is stationary, D max is the maximum allowable duty cycle, D move It is the basic duty cycle of the shift actuator during movement.

[0073] Step S50: When the actual torque is less than and greater than or equal to This is the second stage of neutral gear shifting, and the actual torque is less than The value of the shift position sensor and the actual torque at the time are recorded as P mid_Start and T mid_Start , and record the torque reduction rate calculated at this time, recorded as Rate Dectq_mid , the shifting force is smaller than that in the first stage. In this stage, the shifting position sensor change rate is kept constant to shift the gear. The constant shifting position sensor change rate is used as the control target, and the output duty cycle of the shifting motor is adjusted in real time by a closed-loop control method, as follows:

[0074]

[0075] Step S60: When the actual torque is less than This is the third stage of neutral shifting, i.e. the final stage of neutral shifting. The value of the shift position sensor P at this time is recorded. end_Start And the actual torque value T of the drive motor end_Start , the control target at this stage is to make the shift position within the neutral range, and the actual torque of the drive motor is close to 0. Therefore, the shift position control at this stage adopts the position closed-loop control with the neutral position as the target to output the shift motor duty cycle, as shown below:

[0076]

[0077]

[0078] In the above formula, The target position for the i-gear shifting in this stage is generally the neutral position;Act (t) is the actual position value of the gear; P Zero The position is determined to be the threshold value; and are the closed-loop control correction coefficients; D max is the maximum duty cycle; P set The upper threshold for the integral and differential parameters; D End_Set D is the upper limit of the score; Idel is the minimum push duty ratio of the shift mechanism without load; t0 is the integration action time, t1 is the integration end time; ΔP max is the maximum change position of the shift position within one cycle; γ1 and γ2 are differential parameter weight coefficients, and γ1+γ2=1.

[0079] Estimated time to remove the gap , then we can get:

[0080]

[0081] In summary, the closed-loop control output duty cycle at this stage is:

[0082]

[0083] The present application utilizes the ratio of the predicted torque reduction time to the predicted neutral gear time to adjust the deceleration effect of the control differential term, increase the total duty cycle of the output, and minimize the time difference as much as possible.

[0084] Reference Figure 5 , Figure 5 This is a schematic diagram of the shift control process of a direct-drive automatic transmission without a synchronizer motor according to an embodiment of the present application.

[0085] In this embodiment, the shifting process control method of a direct-drive automatic transmission without a synchronizer motor of the present application adopts a gear sleeve meshing structure with a long and short tooth distribution method, combined with a target speed crossing speed regulation method, and because the long and short tooth distribution during the meshing stage reduces the probability of top teeth, the success rate of gear shifting is improved.

[0086] Further, in some feasible embodiments, whether the torque reduction to neutral gear shifting stage is completed is mainly judged in the following manner: Figure 4 , Figure 4 The method further includes:

[0087] Step A1, determining whether the current gear position and the target gear position share a shift actuator;

[0088] Step A2, if a shift actuator is shared, determining whether the actual position of the gear shift is within the range of the lower limit top gear position and the upper limit top gear position; if the actual position of the gear shift is within the range of the lower limit top gear position and the upper limit top gear position, the torque reduction to neutral shifting stage is terminated;

[0089] Step A3, if the shift actuator is not shared, determine whether the shift position is within the neutral center position threshold; if the shift position is within the neutral center position threshold, the torque reduction to neutral shift phase ends, and enters the motor speed adjustment to eliminate the gear idle stroke phase; if the shift position is not within the neutral center position threshold, continue to execute A1, A2, A3 until the shift position is within the neutral center position threshold.

[0090] In this embodiment, one gear shift actuator can shift two gears without a gear selection process. Figure 4 middle, and They are the positions of the top teeth in two directions of the shift actuator shift head, that is, the top teeth positions of the two gears. is the lower limit top tooth position, is the upper limit top tooth position, λ L and λ H are correction coefficients, not greater than 1, is the neutral center position value, ΔP Neu The threshold value for determining the shift position as neutral.

[0091] Further, based on the above embodiments, referring to Figure 2 The present invention discloses a method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor, which specifically includes the following steps when the motor speed is adjusted to eliminate the idle travel of the gear:

[0092] Step S70, after the torque reduction to neutral gear process is completed, the drive motor speed regulation and elimination of the target gear axial idle stroke stage is entered, that is, the motor speed regulation to eliminate the gear idle stroke stage. Since the present application is based on a direct-drive automatic transmission without a synchronizer, when actually engaging the gear, there must be a certain speed difference between the sliding gear sleeve and the gear shaft before engaging the gear, so that the target gear can be smoothly engaged to minimize the probability of top gear. At the same time, when engaging the gear, the speed change rate of the sliding gear sleeve and the target gear shaft must be kept as close as possible to reduce the impact when engaging the gear. The speed regulation stage is divided into two stages: the speed and speed synchronization preparation stage S71 and the speed and speed synchronization stage S72. The details are as follows:

[0093]

[0094] in, is the target value for the speed regulation of the driving motor, is the basic value of the speed regulation of the driving motor, is the speed correction value, which is related to the up / down gear mode and the output shaft speed state, n Pre_step is the speed correction value in the rate synchronization preparation phase, n Precision To drive the motor control accuracy, Flag Pre_step Flag for the rate synchronization preparation phase. Syn_step It is the mark of the speed and rotational speed synchronization stage, i represents the target gear, and the specific calculation is as follows:

[0095]

[0096] Among them, n b The speed difference is calibrated as the basis, is the speed difference correction coefficient when shifting up, is the speed difference correction coefficient when downshifting, z L is the number of full-size meshing teeth, z A is the total number of meshing teeth, It is the speed difference correction coefficient in the speed synchronization preparation phase when upshifting. It is the speed difference correction coefficient in the speed synchronization preparation phase when downshifting. Current is the current gear, Gear Target The target gear is set. After the speed and speed synchronization preparation phase is completed, the speed and speed synchronization is officially started. The specific control is as follows:

[0097] Step S71, the dynamic target speed is used in the preparatory stage before the speed and speed synchronization. The dynamic target speed is related to the output shaft speed and is controlled by proportional parameters as follows:

[0098]

[0099] In the above formula, For this stage, the driving motor controls the torque value; Δn Set The speed reaches the target value judgment threshold; T M_MaxLim It is the maximum torque limit value of the driving motor; is the proportional control parameter.

[0100] Step S72, after the speed and speed synchronization preparatory stage is completed, the speed and speed synchronization is performed, and the dynamic target speed rate and dynamic target speed are also used, combined with the crossing target speed speed regulation method, using the cascade speed rate with speed rate feedforward gain, and the speed controller to adjust the speed rate and speed, as shown below:

[0101]

[0102] Δn Mot_Act (t) = n Mot_Act (t)-n Mot_Act (t-ΔT)

[0103]

[0104] in, The speed change rate reaches the target value judgment threshold; is the cascade speed proportional gain, is the speed integral gain, is the speed change rate feedback gain, is the feedforward speed change rate proportional gain.

[0105] In this embodiment, a dynamic target speed rate and a dynamic target speed are used simultaneously, combined with a crossing target speed control method, and a cascade speed rate with a speed rate feedforward gain and a speed controller are used to adjust the speed rate and speed, thereby improving the gear shift shock problem caused by excessive speed difference or speed change rate at the moment of gear sleeve engagement.

[0106] In the above speed regulation stages S71 and S72, a two-stage control method is used to eliminate the axial idle travel of the gear. The first stage S73 adopts a nonlinear single-class proportional parameter control. Figure 6 In order to avoid overshoot and tooth knocking as much as possible, the second stage S74 adopts a periodic constant duty cycle, fixed time period, and intermittent movement conservative control method, including the head retraction process. These two stages are carried out simultaneously with the speed regulation and do not occupy other time. The specific steps are as follows:

[0107] Step S73, the first stage of eliminating the axial idle travel when the gear is engaged, adopts nonlinear single-like proportional parameter control:

[0108]

[0109] In the above formula, Eliminate the first stage gear-engaging target position for the gear-engaging axial idle stroke; For this stage, the gear position reaches the target position determination threshold; P Syn_Start The actual value of the gear shift position when the motor speed is adjusted to eliminate the idle travel stage in gear.

[0110] Step S74, the second stage of eliminating the axial idle stroke when engaging the gear, adopts a conservative control method with periodic constant duty cycle, fixed time period, and intermittent movement, including a shift head retraction process; wherein, the shift head retraction process is: if the S71 and the S72 of the speed regulation stage are completed before or at the same time as this stage, then directly enter the gear engagement to speed gear synchronization stage, otherwise, after the gear engagement axial position reaches the set point, a small amount of set stroke retraction is performed to retract the set stroke.

[0111] In this stage, the duty cycle of the shift motor is output periodically. If the speed regulation is completed before or at the same time as this stage, it will directly enter the gear shift gear synchronization stage. Otherwise, after the gear axial position reaches the set point, it will then perform a small amplitude set stroke retreat. The specific control strategy is as follows:

[0112]

[0113] Among them, t Count is the actual working time of the shift motor in the cycle, is the set shift motor working time, P Act (t s ) is the position when the shift motor starts working, P Act (t Count ) is the shift motor working t Count The position at which Step The shift position difference within a working cycle of the set shift motor is limited. Eliminate the second stage gear shift target position for axial idle travel. To return to the target position, is the threshold for reaching the target position when retreating, δ i P is the gear shift duty cycle correction factor. bias is the position change rate condition when the set back-off duty cycle is corrected, D bias It is the fallback duty cycle correction value.

[0114] Further, based on the above embodiments, referring to Figure 2 The present invention relates to a method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor. In the stage of shifting to gear synchronization, the method specifically includes:

[0115] Step S80, after the speed regulation of the driving motor is completed and the axial idle stroke of the gear is eliminated, the gear shifting gear matching synchronization stage is entered. In this stage, the shift position adopts a closed-loop control method to follow the set gear curve. If a top tooth appears, the shift position retreats to the neutral direction by a set stroke (step response) and then continues to follow the set gear curve to engage the gear. After the shift position reaches the terminal position area of ​​this stage, the speed of the driving motor is adjusted to cause a difference in the speed rate of the gear and the gear sleeve to complete the gear matching and eliminate the circumferential gap between the teeth. Since the shift motor has a probability of top tooth stalling during this gear phase, causing the motor temperature to rise and the performance to decline, the control of this stage introduces the motor current to participate in the control process. The specific control method of step S80 is as follows:

[0116] Step S81, adopting a three-closed-loop control method of position, speed and acceleration that considers the gravity acceleration component that changes with the slope to feed forward and follow the set gear-entry curve. If the gear is at the top, the shift position is retreated to the neutral direction by a set stroke and then continues to follow the set gear-entry curve to engage the gear;

[0117] According to the meshing characteristics of the gear sleeve, in this stage, the gear position curve is set according to the meshing state using the fast-slow-fast-slow gear shifting method, as shown below:

[0118] when When , the gear-entry target curve is as follows:

[0119]

[0120] Among them, P Wait_Start The actual gear position value when entering this stage. For this stage, the target position is entered. is the neutral position value of gear i, ΔT is the operation cycle, generally 10ms, N is the duration of this stage, which is a positive integer. It is the retraction position when the shift motor is blocked.

[0121] when When , the gear-entry target curve is as follows:

[0122]

[0123] Where P Wait_Start1 The actual gear position value when entering this stage. The target position for this stage is ΔP. The position difference with M+1 cycles, where M is the duration of this phase, which is a positive integer.

[0124] In summary, we can know that:

[0125]

[0126] The gear-entry curve in this stage follows. Since the gear sleeve is affected by gravity acceleration when going up and down slopes, the control in this stage adopts the position, speed and acceleration three-loop control that considers the gravity acceleration component feedforward that changes with the slope. The gravity acceleration feedforward is related to the slope and can be corrected by the slope sensor on the vehicle. The control mode is switched by monitoring the state of the motor current, as follows:

[0127] According to the characteristics of the gear shift actuator and the gear sleeve meshing scheme, the outermost position loop output design of this application is as follows:

[0128]

[0129] in, is the position loop output, and are the proportional and integral gains of the position loop, The gear shift target position for this stage is Pzero is the threshold for determining whether the actual position reaches the target position, λ pw and λ iw is the nonlinear correction coefficient of PI parameters, as follows:

[0130]

[0131] In the above formula, α is the calibration adjustment coefficient, P iw_downLm is the lower limit of integration, P iw_upLm is the upper limit of the integral, P iw_Mid is the difference between the target position and the actual position when the correction coefficient is maximum, β is the coefficient when the integral upper limit is less than 1.

[0132] The speed loop of the middle layer adopts PI control, and its output is as follows:

[0133]

[0134] in, is the speed output, V zero To determine whether the speed loop has reached the output target threshold, and They are the speed loop proportional and integral gain respectively. The inner acceleration loop also uses PI control, and its output is as follows:

[0135]

[0136] In the above formula, is the acceleration loop output, A zero is the threshold for determining whether the acceleration loop reaches the output target, s Judge To determine whether the direction of gravity acceleration component is consistent with the direction of gear shift acceleration, and are the proportional and integral gains of the acceleration loop, and θ is the slope angle. In summary, the closed-loop output of this stage is:

[0137]

[0138] Step S82, after the gear shift position reaches the end position area of ​​the gear shifting and gear matching synchronization stage, adjust the speed of the drive motor to form a speed rate difference between the gear and the gear sleeve to complete the gear matching and eliminate the circumferential gap between the teeth; wherein, the method of adjusting the speed of the drive motor includes: constructing an optimal target speed rate function based on the classical mechanics elastic collision theory and the physical difference between the gear sleeve gap.

[0139] when When the gear shift motor stops, it enters the gear shift synchronization stage. It is necessary to adjust the speed change of the input end of the drive motor according to the speed change state of the output shaft and the classical mechanics elastic collision theory between gear sleeves. The specific adjustment method is as follows:

[0140] According to the structure of the gear sleeve, it can be known from the classical elastic collision theory that the impact kinetic energy of the collision between two objects is:

[0141]

[0142] The impact force can be obtained as:

[0143]

[0144] in, are the moments of inertia of the meshing gear sleeve end, is the meshing radius of the gear sleeve, Δn Mot_Aim (t) is the target speed rate, θ i For comprehensive flexibility.

[0145] It can be seen from the above formula that the magnitude of the impact force is directly related to the relative speed and relative speed acceleration of the gear sleeve. In this speed change gear synchronization stage, the present application adjusts the speed of the drive motor end based on the impact theory to reduce the synchronization impact, as shown below:

[0146]

[0147] in, is the relative rotation arc length of the gear sleeve. One of the control objectives at this stage is to ΔL i For this purpose, the maximum gap distance between the teeth of the gear sleeve in the meshing section is set. Another control goal is to make the impact force as small as possible. It can be seen that this speed regulation stage can be transformed into the following optimization objective function to find the optimal solution and optimal target speed rate:

[0148] make:

[0149] Then we can get:

[0150]

[0151] st|Δn Mot_Aim (t)|≤Δn upLim ,

[0152] in, is the weight coefficient, the longer the duration The larger the value is and the smaller it is not greater than 1, the upLim The upper limit of the speed change rate.

[0153] We can further obtain: Δn Mot_Aim (t) * =arcmin(J(Δn Mot_Aim (t)))

[0154] Therefore, the speed control in this stage is as follows:

[0155]

[0156] In the above formula, Δn Mot_Aim (t) * is the optimal target speed rate, and are the speed control proportional and integral gains respectively, To make the drive motor rotate with minimum torque.

[0157] In this embodiment, the present application adopts the position, speed and acceleration three-closed-loop shift position control that considers the gravity acceleration component feedforward that changes with the slope, and comprehensively considers the rough road conditions in the mining area, thereby improving the robustness of the shift position control during the transmission shift process and optimizing the shift quality to a certain extent. The present application also constructs an objective function with maximum displacement and minimum impact based on the structure of the gear sleeve and the classical elastic collision theory, optimizes the target parameters of the drive motor speed regulation in the synchronization stage, and reduces the impact in the synchronization stage.

[0158] Further, based on the above embodiments, before the complete gear shifting to the torque increase stage, the shifting process control method of the direct-drive automatic transmission without a synchronizer motor of the present application further includes:

[0159] If the following conditions are met at the same time during step S80, it can be determined that the gear shifting to gear-shifting synchronization phase is completed and the full gear shifting to torque increase phase is entered. The gear shifting to gear-shifting synchronization end condition is:

[0160]

[0161] in, is the relative rotation arc length of the gear sleeve in the circumferential direction, is the driving motor torque, The minimum torque required to drive the motor is n Mot_Act (t) is the current driving motor speed, n DM_B (t) is the speed value of the driving motor, Δn Set The speed reaches the target value judgment threshold, Δn Mot_Act (t) is the current driving motor speed, Δn Rate The driving motor torque is The target gear is gear i and the speed rate when there is no load on the output end of the automatic transmission. is the calibration adjustment factor.

[0162] Further, based on the above embodiments, referring to Figure 3 The present invention relates to a method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor. In the stage of fully shifting to torque increase, the method specifically includes:

[0163] Step S90, after completing the speed gear synchronization, enters the full gear shifting to torque increase stage. In this stage, the shift position adopts a semi-closed loop control method, and the gear is shifted in a driving torque adjustment manner. During the gear shifting process, the torque is increased and restored at the same time. After the shift position reaches the set position range, the shift head retreats to the neutral direction for a set distance, and finally the torque is restored to the torque required by the driver. At this point, the transmission shifting process is completed. This process adjusts the restored torque value based on the load characteristics of the shift actuator. The gear shifting method of this application is that a DC brush motor drives the ball screw to drive the shift head to shift gears.

[0164] Among them, the gear shifting method adjusted by driving torque includes: setting a gear shifting and retracting position following curve; constructing a physical relationship between the gear shifting motor and the gear shifting position based on the ball screw structure; the gear shifting motor outputs a constant duty cycle; the torque increase based on the gear shifting position curve to restore the torque also includes: constructing a relationship between the load characteristics of the gear shifting motor of the ball screw structure and the driving torque; according to the relationship between the load characteristics of the gear shifting motor and the driving torque, as well as the torque, voltage and motion characteristics of the DC brushed motor, setting the position curve so that the driving motor torque gradually increases with the change of the gear shifting position.

[0165] Specifically, the above step S90 includes:

[0166] The physical relationship between the torque output by the shift motor and the drive motor is as follows:

[0167]

[0168] In the above formula, T e is the motor electromagnetic torque, is the output torque of the driving motor during the recovery torque period, f1 is the friction coefficient of the gear sleeve meshing surface, l i is the distance between the center of the gear sleeve and the center of the screw, θ1 is the lead angle of the screw thread, θ2 is the friction angle, J is the moment of inertia of the motor, ω is the angular velocity of the motor, B is the damping coefficient of the motor, and K T is the torque constant, K E is the back electromotive force constant, and K T =K E , U a is the armature voltage, I a is the armature current, R a is the total resistance of the loop, L a is the total loop inductance.

[0169] The present application determines the gear-entry curve of the shift position, and through the geometric relationship, the curve of the screw angular velocity ω, that is, the value of the gear-entry process, can be obtained. At the same time, a constant duty cycle is adopted. According to the physical relationship between the shift motor and the output torque of the drive motor, the output torque of the drive motor can be adjusted. The size of the screw angular velocity is adjusted to make the actual curve follow the target curve to complete the torque shifting process at this stage. The specific control process is as follows:

[0170] The relationship between the axial displacement of the screw nut and the angular velocity of the shift motor is:

[0171]

[0172] In the above formula, s is the gear shift position entry curve at this stage, and L is the lead of the screw. If s is known, the screw angular velocity ω can be known. The gear shift position curve at this stage is divided into two sections: the entry curve and the retraction curve, as follows:

[0173] The gear-entry curve is:

[0174]

[0175] Where P Int_Start1 The actual shift position value at the beginning of this phase, The target shift position value for this stage is ΔP' The position difference with the set Q+1 cycles, where Q is the set duration of this stage, which is a positive integer.

[0176] The fallback curve is:

[0177]

[0178] In the above formula, For this stage, the target position is P Int_Start2 The actual shift position value at the beginning of this phase, The target shift position value for this stage, ΔP” is The difference between the approach curve and the shift position. The number of cycles of , which is a positive integer.

[0179] From the physical relationship between the shift motor characteristic parameters and the output torque of the drive motor, it can be seen that when the angular velocity ω(t) of the shift motor is known and the output duty cycle is constant, the output torque of the drive motor during the torque recovery process is:

[0180]

[0181] Where, H(ω(t),U a (t)) is the output torque of the drive motor and the angular velocity of the shift motor ω(t) and the output duty cycle of the controller at this stage The functional relationship of T Drive (t) is the driver's required torque, T Act_Es (t) is the actual output torque of the driving motor when the shift position reaches the target position, and a is the actual torque of the driving motor from T Act_Es (t) Restore to the driver's required torque T Drive (t) is the number of cycles required, which is a positive integer, U Total The power supply voltage for the drive motor in the controller is usually 12 or 24V. For this stage, the controller outputs the duty cycle, D Tj is the duty cycle when the current is the maximum allowable locked-rotor current value, C i Flag is the adjustment factor. Shift_End The gear shifting end state is 1, which indicates the gear shifting is completed. When the actual torque of the driving motor T Act (t) and the driver's required torque T Drive When (t) is close to each other, the gear shifting process of this transmission is completed.

[0182] In this embodiment, by adopting the method of setting a back-off distance after engaging a gear, a gap is created between the shift slider and the gear sleeve, thereby reducing the wear of the shift slider under the high-speed rotation of the gear sleeve when the gear sleeve is engaged, thereby increasing the life of the transmission assembly.

[0183] Based on the above embodiments, the present invention discloses a method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor. In the shifting process of a powertrain solution of a direct-drive automatic transmission without a synchronizer motor, there are problems such as long shifting time, obvious power interruption, shifting shock, low gear engagement success rate and easy wear of the shift slider, which cause complaints from drivers. Based on the characteristics of direct motor drive, the gear shifting time is overlapped with the torque clearing, speed regulation and torque increasing process of the drive motor, and a closed-loop linkage control method is adopted to reduce the shifting time of the entire transmission. At the same time, according to the mechanical structure of the transmission shifting, a gear shifting curve is set based on theoretical calculation combined with empirical correction method, and a gear shifting torque increasing method of increasing torque while shifting is adopted to restore torque in time, weaken power interruption during the shifting process, and improve the driving experience of the driver. A gear sleeve meshing structure with a long and short tooth distribution method is adopted, combined with a target speed crossing speed regulation method, and a dynamic target speed rate and a dynamic target speed are adopted at the same time, and a speed belt is used. The cascade speed rate of the rate feedforward gain and the speed controller adjust the speed rate and speed, which improve the gear shift shock problem caused by excessive speed difference or speed change rate at the moment of gear sleeve engagement, and reduce the probability of top tooth due to the long and short tooth spacing in the engagement stage, thereby improving the success rate of gear engagement; in addition, the present application adopts a three-loop shift position control of position, speed and acceleration that considers the gravity acceleration feedforward that changes with the slope, and comprehensively considers the rugged road conditions in the mining area, thereby improving the robustness of the shift position control during the transmission shift process, and optimizing the shift quality to a certain extent; the present application constructs an objective function with maximum displacement and minimum impact based on the structure of the gear sleeve and the classical elastic collision theory, optimizes the speed regulation target parameters of the drive motor in the synchronization stage, and reduces the impact in the synchronization stage; finally, the present application adopts a method of setting a distance after gear engagement, so that there is a gap between the shift slider and the sleeve, reducing the wear of the shift slider under the high-speed rotation of the sleeve, and improving the life of the transmission assembly.

[0184] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0185] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor, characterized in that: The method is applied to a gear sleeve meshing structure with a long-short tooth arrangement, and comprises: The gear shifting process is divided into four stages: torque reduction to neutral gear stage, motor speed regulation to eliminate gear idle travel stage, gear shifting to gear shifting synchronization stage, and complete gear shifting to torque increase stage. At each stage of the shifting process, the current vehicle and gearbox status information and related sensor information are collected, including: accelerator pedal position, brake travel position, actual torque of the drive motor, shift position of each gear shift sensor, slope sensor value, shift motor current, drive motor speed, current gear, target gear, output shaft speed and shifting process status, so as to control the shifting process; among which, In the torque reduction to neutral gear shifting stage, the gear shifting is performed according to the actual torque change combined with the estimated time feedforward, open-closed loop joint control and different working conditions; In the stage of motor speed regulation to eliminate the idle travel in gear, dynamic target speed rate and dynamic target speed are used, combined with the target speed crossing speed regulation method to perform speed control, and a cascade speed rate with a speed rate feedforward gain and a speed controller are used to adjust the speed rate and speed to synchronize the speed and speed.

2. The method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor as claimed in claim 1, characterized in that: Before the torque reduction to neutral gear shifting stage, the method further includes: S10: monitoring the state of the gear shifting process, and if the gear shifting starts, recording the gear shifting start torque, and obtaining the basic target speed of the drive motor according to the current gear position, the target gear position, and the output shaft speed; S20: determining a torque reduction rate according to the current driving motor speed, the actual driving motor torque, the throttle level, and the braking stroke; S30: Calculating an estimated torque reduction time based on the torque reduction rate.

3. The method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor as claimed in claim 2, characterized in that: In the torque reduction to neutral gear shifting stage, shifting the gear according to actual torque change combined with estimated time feedforward, open-closed loop joint control and different working conditions includes: S40: In the first stage of neutral shifting, the shift motor uses an open-loop duty cycle to intermittently shift gears, while monitoring the current and actual torque of the shift motor; S50: In the second stage of neutral gear shifting, the shift position sensor value and the actual torque are collected, the torque reduction rate is calculated, and the shift position sensor change rate is kept constant to shift the gear. The output duty cycle of the shift motor is adjusted in real time by a closed-loop control method with the constant shift position sensor change rate as the control target; S60: In the third stage of neutral gear shifting, the shift position sensor value and the actual torque value of the drive motor are collected, and the duty cycle of the shift motor is output by position closed-loop control with the neutral position as the target.

4. The method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor as claimed in claim 1, characterized in that: Before the motor speed is adjusted to eliminate the idle travel in gear, the method further includes: A1: Determine whether the current gear and the target gear share a shift actuator; A2: If a shift actuator is shared, it is determined whether the actual position of the gear shift is within the range of the lower limit top gear position and the upper limit top gear position; if the actual position of the gear shift is within the range of the lower limit top gear position and the upper limit top gear position, the torque reduction to neutral shifting stage is completed; A3: If a shift actuator is not shared, determine whether the shift position is within the neutral center position threshold; if the shift position is within the neutral center position threshold, the torque reduction to neutral shift phase ends, and enter the motor speed regulation to eliminate the gear idle stroke phase; if the shift position is not within the neutral center position threshold, continue to execute A1, A2, A3 until the shift position is within the neutral center position threshold.

5. The method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor as claimed in claim 1, characterized in that: In the stage of regulating the motor speed to eliminate the idle stroke in gear, the dynamic target speed rate and the dynamic target speed are used, and the speed regulation mode of crossing the target speed is combined to perform speed regulation control, and the cascade speed rate with speed rate feedforward gain and the speed controller are used to adjust the speed rate and the speed to synchronize the speed and the speed, including the speed regulation stage: S71: The speed and speed synchronization preparation stage uses dynamic target speed and proportional parameters for control; S72: In the speed and rotational speed synchronization stage, a dynamic target rotational speed and a dynamic target rotational speed are adopted, and a cascaded rotational speed with a rotational speed feedforward gain and a rotational speed controller are used to adjust the rotational speed and the rotational speed for speed synchronization.

6. The method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor as claimed in claim 5, characterized in that: In the stage of adjusting the motor speed to eliminate the idle travel in gear, the method further includes eliminating the axial idle travel in gear: S73: adopts nonlinear single class proportional parameter control; S74: adopts a periodic constant duty cycle, fixed time period, intermittent movement conservative control method, including a shift head retraction process; wherein, the shift head retraction process is: if the S71 and the S72 of the speed regulation stage are completed before or at the same time as this stage, then directly enter the gear shift to gear synchronization stage, otherwise after the gear engagement axial position reaches the set point, a small amplitude set stroke retraction is performed to retract the set stroke.

7. The method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor as claimed in claim 1, characterized in that: During the gear shifting to gear-shifting synchronization stage, the method includes: S81: A three-loop control method of position, speed and acceleration is adopted to follow the set gear-entry curve by taking into account the gravity acceleration component feedforward that changes with the slope. If the gear hits the top gear, the shift position is retreated to the neutral direction by a set distance and then continues to follow the set gear-entry curve to engage the gear; S82: After the gear shift position reaches the end position area of ​​the gear shifting to gear shifting synchronization stage, the speed of the drive motor is adjusted to form a speed rate difference between the gear and the gear sleeve to complete the gear alignment and eliminate the circumferential gap between the teeth; wherein, the method of adjusting the speed of the drive motor includes: constructing an optimal target speed rate function based on the elastic collision theory of classical mechanics and the physical difference of the gap between the gear sleeves.

8. The method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor as claimed in claim 7, characterized in that: Before the full gear shifting to the torque increasing stage, the method further includes: If the gear shifting gear synchronization termination condition is met, it is determined that the gear shifting gear synchronization phase is terminated, and the full gear shifting gear synchronization phase is entered. The gear shifting gear synchronization termination condition is: in, is the relative rotation arc length of the gear sleeve in the circumferential direction, is the driving motor torque, The minimum torque required to make the drive motor rotate, n Mot_Act (t) is the current driving motor speed, n DM_B (t) is the speed value of the driving motor, Δn Set The speed reaches the target value judgment threshold, Δn Mot_Act (t) is the current driving motor speed, Δn Rate The driving motor torque is The target gear is gear i and the speed rate when there is no load on the output end of the automatic transmission. is the calibration adjustment factor.

9. The method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor as claimed in claim 8, characterized in that: In the stage of fully shifting into gear and increasing torque, the method comprises: Adopting semi-closed loop control mode, the gear is shifted by driving torque adjustment; When shifting into a gear, torque is increased based on the gear shift position curve to restore the torque. When the gear shift position reaches the set position range, the shift knob retreats a set distance in the neutral direction, and then the torque is restored to the required torque. When restoring the torque to the required torque, the restored torque value is adjusted based on the load characteristics of the gear shift actuator.

10. The method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor as claimed in claim 9, characterized in that: The shifting in gear by driving torque adjustment includes: setting a shifting and retracting position following curve; constructing a physical relationship between a shifting motor and a shifting position based on a ball screw structure; and outputting a constant duty cycle of the shifting motor; The torque increase based on the shift position curve to restore the torque also includes: constructing the relationship between the load characteristics of the shift motor of the ball screw structure and the driving torque; setting the position curve according to the relationship between the load characteristics of the shift motor and the driving torque, as well as the torque, voltage and motion characteristics of the DC brush motor, so that the driving motor torque gradually increases with the shift position.

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