A method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor

Abstract

This application relates to a shifting process control method for a direct-drive automatic transmission without a synchronizer motor, belonging to the field of automotive automatic transmission control technology. It is applied to a gear sleeve meshing structure with a long and short tooth arrangement. The method includes: dividing the shifting process into four stages: torque reduction to neutral shifting stage, motor speed adjustment to eliminate gear idle travel stage, gear engagement to gear synchronization stage, and full gear engagement to torque increase stage. During each stage of the shifting process, the method collects current vehicle and transmission status information, as well as relevant sensor information, including: accelerator pedal position, brake travel position, actual drive motor torque, shift sensor position for each gear, slope sensor value, shift motor current, drive motor speed, current gear, target gear, output shaft speed, and shifting process status, to control the shifting process.

Description

Technical Field

[0001] This application relates to the field of automotive automatic transmission control technology, specifically a method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor. Background Technology

[0002] In recent years, with continuous technological updates and upgrades, the automotive industry has experienced vigorous growth, with new technologies emerging one after another. This is especially true for the commercial vehicle industry, which has seen further development. In the commercial mining truck sector, due to the special nature of their operation, the requirements for transmissions differ significantly from those of traditional light and heavy-duty trucks. Mining trucks frequently operate under conditions of low speed, heavy load, and bumpy conditions, thus requiring high transmission efficiency and torque capacity from the transmission system. With the innovation of electric drive technology, electric mining trucks are gradually becoming mainstream, and direct-drive automatic transmissions without synchronizers are slowly coming into focus. Due to their unique structure, the shift control process of these transmissions has attracted considerable research from scholars and institutions.

[0003] Currently, for direct-drive automatic transmissions without synchronizers, the shift control process is basically as follows: first, reduce torque; then, shift to neutral; next, adjust speed; then, engage gear; and finally, increase torque. The specific control methods for each of these processes vary from person to person. Regardless of the method, the ultimate goal is to achieve smooth, shock-free shifting, short power interruption time, and a high shift success rate. Many current control methods still fall short in shortening shift time, reducing shift shock, and improving shift success rate. Existing gear sleeve meshing structures with alternating long and short teeth can reduce straight-tooth impact noise to some extent, and the guiding effect of the long teeth further enhances the driver's experience, resulting in a smoother and more comfortable shift.

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

[0005] To address the shortcomings of existing technologies, this application provides a shifting process control method for a direct-drive automatic transmission without a synchronizer motor, aiming to provide a shifting process control method that results in smoother shifting, reduced shifting shock, and shorter shifting time.

[0006] To achieve the above objectives, this application provides a method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor, applied to a gear sleeve meshing structure with alternating long and short teeth. The method includes:

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

[0008] During each stage of the gear shifting process, the current status information of the vehicle and transmission, as well as relevant sensor information, are collected. This status information and sensor information include: accelerator pedal position, brake travel position, actual torque of the drive motor, shift positions of each gear shift sensor, gradient sensor value, shift motor current, drive motor speed, current gear, target gear, output shaft speed, and shifting process status, all for the purpose of shifting process control.

[0009] During the torque reduction to neutral shift stage, the shift is performed based on the actual torque change, combined with estimated time feedforward, open-loop and closed-loop control, and different operating conditions.

[0010] During the stage of speed regulation of the motor to eliminate the idle travel of the gear shift, speed regulation control is carried out by using dynamic target speed rate and dynamic target speed combined with the speed regulation method of passing through the target speed. Cascaded speed rate with speed rate feedforward gain and speed controller are used to adjust the speed rate and speed to achieve speed and speed synchronization.

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

[0012] S10: Monitor the status of the gear shifting process. If the gear shifting starts, record the gear shifting start torque and obtain the basic target speed of the drive motor based on the current gear, the target gear, and the output shaft speed.

[0013] S20: Determine the torque reduction rate based on the current drive motor speed, actual drive motor torque, throttle position, and brake stroke.

[0014] S30: Calculate the expected torque reduction time based on the torque reduction rate.

[0015] Optionally, the torque reduction to neutral shift stage, based on actual torque changes combined with estimated time feedforward, open-loop and closed-loop control, and different operating conditions, includes the following:

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

[0017] S50: In the second stage of neutral shift, when the actual torque is in the range of 1 / 3 to 2 / 3 of the torque at the start of shift, 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 gear. With the constant shift position sensor change rate as the control target, the output duty cycle of the shift motor is adjusted in real time using a closed-loop control method.

[0018] S60: In the third stage of neutral shift, 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 using a position closed-loop control with the neutral position as the target.

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

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

[0021] A2: If a single shift actuator is used, determine whether the actual position of disengaging the gear is within the range of the lower limit tooth position and the upper limit tooth position; if the actual position of disengaging the gear is within the range of the lower limit tooth position and the upper limit tooth position, the torque reduction to neutral shift stage ends.

[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 stage ends, and the motor speed regulation to eliminate shift travel stage begins. If the shift position is not within the neutral center position threshold, continue executing A1, A2, and A3 until the shift position is within the neutral center position threshold.

[0023] Optionally, in the stage where the motor speed is adjusted to eliminate the idle travel during gear engagement, a dynamic target speed rate and a dynamic target rotational speed are used in combination with a speed regulation method that crosses the target speed. This involves using a cascaded speed rate with feedforward gain and a speed controller to adjust the speed rate and rotational speed for speed and rotational synchronization, including the speed regulation stage:

[0024] S71: During the preparation stage before speed and rotational speed synchronization, dynamic target rotational speed and proportional parameters are used for control;

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

[0026] Optionally, during the stage of speed adjustment of the motor to eliminate the idle travel during gear engagement, the method further includes a stage of eliminating the axial idle travel during gear engagement:

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

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

[0029] Optionally, during the gear engagement and shift synchronization phase, the method includes:

[0030] S81: The three-closed-loop control method of position, velocity and acceleration, which takes into account the gravity acceleration component that changes with the slope, follows the set gear engagement curve. If the gear is hit, the shift position will retract the set stroke towards neutral and then continue to follow the set gear engagement curve to engage gear.

[0031] S82: After reaching the end position of the gear shifting and gear matching synchronization stage, the drive motor speed is adjusted to create a speed difference between the gear and the gear sleeve to complete the gear matching and eliminate the circumferential backlash between the teeth; wherein, the method of adjusting the drive motor speed includes: constructing an optimal target speed function based on the classical mechanical elastic collision theory and the physical difference between the gear and the gear sleeve backlash.

[0032] Optionally, before the full engagement to torque increase phase, the method further includes:

[0033] If the conditions for ending gear shift synchronization are met, then the gear shift synchronization phase is considered complete, and the process enters the full gear shift to torque increase phase. The conditions for ending gear shift synchronization are:

[0034]

[0035] in, The relative circumferential rotational arc length of the gear sleeve. For the torque of the drive motor, To achieve the minimum torque required for the drive motor to rotate, n Mot_Act (t) represents the current speed of the drive motor, n DM_B (t) represents the speed regulation value of the drive motor, Δn Set To determine the threshold for the rotational speed to reach the target value, Δn Mot_Act (t) represents the current speed of the drive motor, Δn Rate The torque of the drive motor is The target gear is i, and the engine speed is when there is no load at the output of the automatic transmission. This is the calibration adjustment factor.

[0036] Optionally, during the stage from full gear engagement to torque increase, the method includes:

[0037] A semi-closed-loop control method is adopted, and gear engagement is achieved through drive torque adjustment;

[0038] While shifting gears, torque is increased based on the shift position curve to restore torque. Once the shift position reaches the set position range, the shift lever retracts a set distance towards neutral, and then the torque is restored to the required torque. When restoring the torque to the required torque, the magnitude of the restored torque value is adjusted based on the load characteristics of the shift actuator.

[0039] Optionally, the gear shifting via drive torque adjustment includes: setting a gear shifting and retraction position following curve; constructing a physical relationship between the shift motor and the shift position based on the ball screw structure; and outputting the shift motor with a constant duty cycle.

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

[0041] This application provides a shifting process control method for a direct-drive automatic transmission without a synchronizer motor, applied to a gear sleeve meshing structure with long and short teeth. The method includes dividing the shifting process into four stages: torque reduction to neutral, motor speed adjustment to eliminate engagement idle travel, gear engagement to gear synchronization, and full engagement to torque increase. During each stage of the shifting process, the method collects current vehicle and transmission status information, as well as relevant sensor information, including: accelerator pedal position, brake travel position, actual drive motor torque, and shift sensor positions for each gear. The system uses slope sensor values, shift motor current, drive motor speed, current gear, target gear, output shaft speed, and shift process status to control the shift process. Specifically, during the torque reduction to neutral shift stage, shifting is performed based on actual torque changes combined with estimated time feedforward, open-loop and closed-loop control, and different operating conditions. During the motor speed adjustment stage to eliminate idle travel, speed control is achieved using dynamic target speed and dynamic target speed combined with a target speed-through speed adjustment method. Cascaded speed rates with speed rate feedforward gain and a speed controller are used to adjust the speed rate and speed for speed and speed synchronization.

[0042] This application provides a method for controlling the shifting process of a synchronizerless direct-drive automatic transmission. Based on the powertrain of the synchronizerless direct-drive automatic transmission, and taking into account the characteristics of direct-drive motors and the mechanical structure of the transmission shifting, this method incorporates the entire shifting position movement process into the torque reduction, speed adjustment, and torque increase processes of the drive motor, thus shortening the transmission shifting time. This application also employs a gear sleeve meshing structure with a long and short tooth arrangement, combined with a target speed regulation method, and uses both dynamic target speed rate and dynamic target rotational speed. A cascaded speed rate and speed controller with feedforward gain is used to adjust the speed rate and rotational speed, improving the shifting shock problem caused by excessive speed difference or speed change rate during gear sleeve meshing. Furthermore, the long and short tooth arrangement during the meshing phase reduces the probability of tooth tipping, improving the success rate of gear engagement. Attached Figure Description

[0043] Figure 1 This is a schematic flowchart of one embodiment of the shifting process control method for a direct-drive automatic transmission without a synchronizer motor according to this application.

[0044] Figure 2 This is a second schematic flowchart of an embodiment of the shifting process control method for a direct-drive automatic transmission without a synchronizer motor according to this application.

[0045] Figure 3 This is a third flowchart illustrating an embodiment of the shifting process control method for a direct-drive automatic transmission without a synchronizer motor according to this application.

[0046] Figure 4 This is a schematic diagram of the process for determining the state of torque reduction to neutral shifting in an embodiment of the torque reduction to neutral shifting process control method for a direct-drive automatic transmission without a synchronizer motor according to this application.

[0047] Figure 5 This is a schematic diagram of the disengagement control flow of an embodiment of the shifting process control method for a direct-drive automatic transmission without a synchronizer motor according to this application.

[0048] Figure 6 This is a schematic diagram of the gear sleeve meshing structure of an embodiment of the shifting process control method for a direct-drive automatic transmission without a synchronizer motor according to this application. Detailed Implementation

[0049] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0050] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0051] In recent years, with continuous technological updates and upgrades, the automotive industry has experienced vigorous growth, with new technologies emerging one after another. This is especially true for the commercial vehicle industry, which has seen further development. In the commercial mining truck sector, due to the special nature of their operation, the requirements for transmissions differ significantly from those of traditional light and heavy-duty trucks. Mining trucks frequently operate under conditions of low speed, heavy load, and bumpy conditions, thus requiring high transmission efficiency and torque capacity from the transmission system. With the innovation of electric drive technology, electric mining trucks are gradually becoming mainstream, and direct-drive automatic transmissions without synchronizers are slowly coming into focus. Due to their unique structure, the shift control process of these transmissions has attracted considerable research from scholars and institutions.

[0052] Currently, for direct-drive automatic transmissions without synchronizers, the shift control process is basically as follows: first, reduce torque; then, shift to neutral; next, adjust speed; then, engage gear; and finally, increase torque. The control methods for each of these processes vary from person to person. Regardless of the method, the ultimate goal is to achieve smooth, shock-free shifting, short power interruption time, and high shift success rate. Many current control methods still fall short in shortening shift time, reducing shift shock, and improving shift success rate. Therefore, this application proposes a new shift process control strategy that, to a certain extent, can make shifting smoother, reduce shock, shorten power interruption time, improve shift success rate, and enhance the adaptability and robustness of the control system.

[0053] Based on the overall concept of the shifting process control method for the direct-drive automatic transmission without synchronizer motor described in this application, various embodiments of the shifting process control method for the direct-drive automatic transmission without synchronizer motor described in this application are proposed.

[0054] This application is based on a direct-drive automatic transmission without a synchronizer motor, applied to a gear sleeve meshing structure with long and short teeth. By changing the meshing structure of the engaging gears and sleeves, the shifting process is subdivided into four stages: torque reduction to neutral, motor speed adjustment to eliminate gear idle travel, gear engagement to gear synchronization, and full engagement to torque increase. During each stage of the shifting process, the current vehicle and transmission status, along with relevant sensor information, are collected, including: accelerator pedal position, brake travel position, actual drive motor torque, shift sensor positions for each gear, gradient sensor value, shift motor current, drive motor speed, current gear, target gear, output shaft speed, and shifting process status, to control the shifting process.

[0055] Specifically, during the torque reduction to neutral shift stage, the shift is performed based on the actual torque change, combined with estimated time feedforward, open-loop and closed-loop control, and different operating conditions; during the motor speed adjustment to eliminate idle travel, a dynamic target speed rate and a dynamic target speed are used, combined with a speed adjustment method that crosses the target speed, for speed control. A cascaded speed rate with speed rate feedforward gain and a speed controller are used to adjust the speed rate and speed for speed and speed synchronization.

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

[0057] In this embodiment, this application provides a method for controlling the shifting process of a synchronizerless motor direct-drive automatic transmission. Based on the synchronizerless motor direct-drive automatic transmission powertrain, the characteristics of motor direct drive, and the transmission shifting mechanical structure, and based on theoretical calculations and experience, the entire shifting position movement process is incorporated into the torque reduction, speed adjustment, and torque increase process of the drive motor, thus shortening the transmission shifting time. This application also employs a gear sleeve meshing structure with a long and short tooth arrangement, combined with a target speed regulation method, and simultaneously uses dynamic target speed rate and dynamic target rotational speed. A cascaded speed rate and speed controller with speed rate feedforward gain is used to adjust the speed rate and rotational speed, improving the shifting shock problem caused by excessive speed difference or speed change rate during gear sleeve meshing. Furthermore, the long and short tooth arrangement during the meshing stage reduces the probability of tooth tipping, improving the success rate of gear engagement.

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

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

[0060] Step S10: Monitor the shifting process status. If shifting begins, record the actual torque of the drive motor at this time as the shift start torque T. Start Simultaneously, based on the collected current gear, target gear, and output shaft speed, the basic target speed of the drive motor is calculated, as shown below:

[0061]

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

[0063] Step S20: Determine the torque reduction rate (Rate) based on the collected current drive motor speed, actual drive motor torque, throttle position, and braking stroke. Dectq (t), as shown below:

[0064]

[0065] Among them, Rate M_maxLim T represents the maximum rate of change of the drive motor torque. If the rate of change of torque exceeds this maximum rate of change, an overcurrent situation will occur. max T is the peak torque of the drive motor. Act (t) represents the actual torque of the drive motor. The positive minimum value, n Mot_Act (t) represents the current speed of the drive motor, n mot_maxLim Rate1, Rate2, Rate3, and Rate4 represent the maximum speed of the drive motor, while Rate4 represents the torque variation within a 10ms cycle on the actual vehicle. All of these actual vehicle calibration parameters are no greater than Rate2. M_maxLim .

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

[0067] TM Total (t) represents the expected torque reduction time.

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

[0069] Furthermore, based on the first and / or second embodiments of the shift process control method for a direct-drive automatic transmission without a synchronizer motor described in this application, a third embodiment of the shift process control method for a direct-drive automatic transmission without a synchronizer motor is proposed. In this embodiment, during the torque reduction to neutral shift stage, disengagement is performed based on the actual torque change combined with estimated time feedforward, open-loop and closed-loop control, and different operating conditions. Specifically, this may include:

[0070] Step S40, from the start of gear shift until the actual torque is greater than or equal to The shift start torque is the first stage of disengaging to neutral. Because the drive motor torque is high at this time, the inner tooth surface of the gear sleeve is tightly engaged with the meshing tooth surface, resulting in high static friction. Therefore, in the initial stage, the shift motor uses an open-loop duty cycle to intermittently disengage gears, while simultaneously monitoring the current and actual torque of the shift motor, as detailed below:

[0071]

[0072] Among them, SM Current SM represents the actual current of the shift motor. CurrentLim To ensure safe current limiting for the shifting motor, TM Count For the duration of high current in the shift motor, TM Set To limit the continuous high current of the shifting motor, D Idle ΔSP is the starting duty cycle of the shift actuator when it is stationary, and ΔSP is the rate of change of the shift position sensor within 10ms. min To determine the rate of change of sensor values ​​when the shift actuator is stationary, D max D is the maximum allowed duty cycle. move This is the basic duty cycle when the gear shifting actuator is in motion.

[0073] Step S50, when the actual torque is less than and greater than or equal to At this point, the second stage of shifting to neutral is recorded, and the actual torque is less than [a certain value]. The value of the shift position sensor and the actual torque at that time are denoted as P. mid_Start and T mid_Start Simultaneously, record the torque reduction rate calculated at this time, denoted as Rate. Dectq_mid The disengagement force is smaller than in the first stage. In this stage, the shift position sensor maintains a constant rate of change for disengagement. Using the constant rate of change of the shift position sensor as the control objective, a closed-loop control method is adopted to adjust the output duty cycle of the shift motor in real time, as detailed below:

[0074]

[0075] Step S60, when the actual torque is less than At this point, the third and final stage of shifting to neutral is recorded, and the value P of the shift position sensor is recorded. end_Start and the actual torque value T of the drive motor end_Start The control objective at this stage is to keep the shift position within the neutral range while ensuring the actual torque of the drive motor is close to zero. Therefore, the shift position control at this stage employs a closed-loop position control outputting the shift motor duty cycle with the neutral position as the target, as detailed below:

[0076]

[0077]

[0078] In the above formula, The target position for disengaging the i-gear at this stage is generally neutral; PAct (t) represents the actual position value of the disengaged gear; P Zero The threshold for determining the position is reached; and These are the closed-loop control correction coefficients; D max P represents the maximum duty cycle. set Upper threshold for the integral and differential parameters; D End_Set D is the upper limit of integration. Idel The minimum duty cycle for the shift mechanism under no load; t0 is the integral activation time, t1 is the integral termination time; ΔP max γ1 represents the maximum change position within one cycle of the shift position; γ2 and γ1 are the weighting coefficients of the differential parameters, and γ1 + γ2 = 1.

[0079] Expected time to remove the gap Then we can obtain:

[0080]

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

[0082]

[0083] This application utilizes the ratio of the expected torque reduction time to the expected neutral shift time to adjust the deceleration effect of the control derivative 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 disengagement control flow of an embodiment of the shifting process control method for a direct-drive automatic transmission without a synchronizer motor according to this application.

[0085] In this embodiment, the gear shifting process control method of the direct-drive automatic transmission without synchronizer motor of this application adopts a gear sleeve meshing structure with long and short teeth, combined with a speed regulation method that crosses the target speed. Furthermore, because the long and short teeth are arranged in a way that reduces the probability of tooth tipping during the meshing stage, the success rate of gear engagement is improved.

[0086] Furthermore, in some feasible embodiments, whether the torque reduction to neutral shift stage is complete is mainly determined in the following manner, referring to... Figure 4 , Figure 4 This is a flowchart illustrating the process of determining the state of torque reduction and neutral shift. Before the motor speed is adjusted to eliminate the idle travel phase, the method further includes:

[0087] Step A1: Determine whether the current gear and the target gear share the same shift actuator;

[0088] Step A2: If a single shift actuator is used, determine whether the actual position of disengaging the gear is within the range of the lower limit tooth position and the upper limit tooth position; if the actual position of disengaging the gear is within the range of the lower limit tooth position and the upper limit tooth position, the torque reduction to neutral shifting stage ends.

[0089] Step 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 stage ends, and the motor speed regulation to eliminate shift idle travel stage begins. If the shift position is not within the neutral center position threshold, continue executing A1, A2, and A3 until the shift position is within the neutral center position threshold.

[0090] In this embodiment, one gear shifting actuator can shift to two gears without a gear selection process. Figure 4 middle, and These refer to the positions of the teeth on the shift lever head of the shift actuator in two directions, i.e., the positions of the teeth for the two gears. This is the lower limit position of the top tooth. λ represents the upper limit position of the tooth. L and λ H These are correction factors, not greater than 1. The value of the center position in neutral, ΔP Neu The threshold for determining whether the gear shift position is neutral.

[0091] Furthermore, based on the above embodiments, referring to Figure 2 The shifting process control method for a direct-drive automatic transmission without a synchronizer motor in this application specifically includes the following during the stage of motor speed adjustment to eliminate the idle travel during gear engagement:

[0092] Step S70, after the torque reduction to neutral is completed, the drive motor speed adjustment and target gear axial free travel elimination stage begins, i.e., the aforementioned motor speed adjustment to eliminate gear engagement free travel stage. Since this application is based on a direct-drive automatic transmission without a synchronizer, a certain speed difference must exist between the sliding sleeve and the gear shaft before engaging the gear to smoothly engage the target gear and minimize the probability of gear collision. Simultaneously, during gear engagement, the speed change rates of the sliding sleeve and the target gear shaft must be kept as similar as possible to reduce the impact during engagement. The speed adjustment stage is divided into two phases: the speed and rotational speed synchronization preparation stage S71 and the speed and rotational speed synchronization stage S72. Details are as follows:

[0093]

[0094] in, The target speed value for the drive motor. This is the base value for driving motor speed regulation. This is a speed adjustment correction value, specifically related to the upshift / downshift mode and the output shaft speed status, n Pre_step For the speed synchronization preparation stage, n is the speed adjustment correction value. Precision To improve the control precision of the drive motor, Flag Pre_step Flag is a marker for the rate synchronization preparation phase. Syn_step This serves as a marker for the synchronization stage of speed and rotational speed, where 'i' represents the target gear. The specific calculation is as follows:

[0095]

[0096] Where, n b Based on the calibrated speed difference, This is the speed difference correction factor during upshifting. z is the speed difference correction factor during downshifting. L z represents the number of full-size meshing teeth. A This represents the total number of meshing teeth. The speed difference correction coefficient during the speed synchronization preparation stage when upshifting. For the speed difference correction coefficient during the rate synchronization preparation stage of downshifting, Gear Current For the current gear, Gear Target Once the target gear is selected, after the speed and speed synchronization preparation phase is completed, the speed and speed synchronization will officially begin, as shown in the following control steps:

[0097] Step S71, the preparation stage before speed and rotational synchronization adopts a dynamic target rotational speed, which is related to the output shaft speed and controlled by proportional parameters, as follows:

[0098]

[0099] In the above formula, For this stage, the drive motor control torque value is Δn. Set The threshold for determining whether the rotational speed reaches the target value; T M_MaxLim This is the maximum torque limit value for the drive motor; This is the proportional control parameter.

[0100] Step S72: After the preparation stage before speed and speed synchronization is completed, speed and speed synchronization is performed. Dynamic target speed and dynamic target rotational speed are used, combined with a target speed regulation method. A cascaded speed rate with speed feedforward gain and a speed controller are used to adjust the speed and rotational speed, as detailed below:

[0101]

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

[0103]

[0104] in, The threshold for determining whether the rate of change of rotational speed reaches the target value; For cascaded speed proportional gain, For speed integral gain, For the speed change rate feedback gain, This is the proportional gain of the feedforward speed change rate.

[0105] In this embodiment, dynamic target speed rate and dynamic target rotation speed are used simultaneously. Combined with the target speed regulation method, cascaded speed rate with speed rate feedforward gain and speed controller are used to adjust the speed rate and rotation speed, which improves the shifting shock problem caused by excessive speed difference or speed change rate at the moment of gear sleeve meshing.

[0106] During the speed regulation stages S71 and S72, a two-stage control method is used to eliminate the axial free travel during gear engagement. The first stage, S73, employs nonlinear single-parameter control, and then refers to... Figure 6 To minimize the risk of gear grinding due to overshoot, the second stage of S74 employs a periodic constant duty cycle, fixed time period, and intermittent conservative control method, including the shift head retraction process. These two stages are performed simultaneously with speed adjustment and do not occupy other time. The specific procedures are as follows:

[0107] Step S73, eliminating the first stage of axial free travel during gear engagement, using nonlinear single-class proportional parameter control:

[0108]

[0109] In the above formula, Eliminate the first-stage gear engagement target position during the axial free travel of the gear engagement axis; This stage determines the threshold for determining when the gear shift position reaches the target position; P Syn_Start This refers to the actual value of the shift position at the moment when the motor speed regulation enters the stage of eliminating the idle travel of the gear shift.

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

[0111] During this stage, the shift motor outputs its duty cycle periodically. If the speed adjustment is completed before or simultaneously with this stage, it directly enters the gear engagement and gear synchronization stage. Otherwise, after the axial position of the engaged gear reaches the set point, it will then perform a small-amplitude set stroke retraction. The specific control strategy is as follows:

[0112]

[0113] Among them, t Count This represents the actual working time of the shifting motor within the cycle. P is the set working time of the shift motor. Act (t s P represents the position when the shift motor starts working. Act (t Count ) for the shift motor to work t Count The position of time, P Step The set shift position difference limit within one working cycle of the shift motor. Eliminate the second-stage gear engagement target position for axial free travel. To revert to the target position, To determine the threshold for retracing to the target position, δ i P is the gear shift duty cycle correction factor. bias To set the position change rate condition during backoff duty cycle correction, D bias This is the rollback duty cycle correction value.

[0114] Furthermore, based on the above embodiments, referring to Figure 2 This application discloses a method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor. Specifically, during the shifting phase from gear engagement to gear synchronization, the method includes:

[0115] Step S80: After the drive motor speed adjustment is completed and the axial free travel during gear engagement is eliminated, the gear engagement and gear synchronization stage begins. During this stage, the shift position uses a closed-loop control method to follow the set gear engagement curve. If a tooth is bumped, the shift position retracts a set distance towards neutral (step response) and then continues to follow the set gear engagement curve. After the shift position reaches the end point of this stage, the drive motor speed is adjusted to create a difference in the speed of the gear and the gear sleeve to complete gear engagement and eliminate circumferential backlash. Because the shift motor may experience tooth bumping and stalling during this gear engagement stage, causing increased motor temperature and performance degradation, motor current is introduced into the control process during this stage. The specific control method for step S80 is as follows:

[0116] Step S81: The position, velocity and acceleration three-closed-loop control method that considers the gravity acceleration component that changes with the slope is used to follow the set gear engagement curve. If the gear is hit, the shift position is moved back to the neutral direction by a set stroke and then the gear is engaged again following the set gear engagement curve.

[0117] Based on the meshing characteristics of the gear sleeve, this stage uses a fast-slow-fast-slow engagement method to set the engagement position curve according to the meshing state, as shown below:

[0118] when At that time, the target curve for gear engagement is as follows:

[0119]

[0120] Among them, P Wait_Start This refers to the actual gear position value when entering this stage. The target position for this stage. Here, ΔT is the neutral position value for gear i, ΔT is the operating cycle (typically 10ms), and N is the set duration of this phase (a positive integer). This is the retraction position when the shift motor stalls.

[0121] when At that time, the target curve for gear engagement is as follows:

[0122]

[0123] In the formula, P Wait_Start1 This refers to the actual gear position value when entering this stage. For this stage, the target position for entering gear is ΔP. The difference between the position and the position of M+1 cycles, where M is the set duration of this phase, which is a positive integer.

[0124] In conclusion, we can conclude that:

[0125]

[0126] During this phase of gear engagement, the gear sleeve is affected by gravitational acceleration when going uphill or downhill. Therefore, the control in this phase adopts a three-loop control system that considers the gravitational acceleration component that changes with the slope, including position, velocity, and acceleration. The gravitational 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 motor current, as detailed below:

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

[0128]

[0129] in, For position loop output, and These are the position loop proportional gain and the integral gain, respectively. For this stage, the target position for gear engagement is P.zero λ is the threshold for determining whether the actual position reaches the target position. pw and λ iw The nonlinearity correction coefficients for the PI parameter are as follows:

[0130]

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

[0132] The speed loop in the intermediate layer uses PI control, and its output is shown below:

[0133]

[0134] in, For speed output, V zero To determine whether the speed loop has reached the output target threshold, and These represent the proportional and integral gains of the velocity loop, respectively. The inner acceleration loop also uses PI control, and its output is shown below:

[0135]

[0136] In the above formula, For acceleration loop output, A zero To determine the threshold for when the acceleration loop reaches the output target, s Judge A symbol is used to determine whether the direction of the component of gravitational acceleration is consistent with the direction of shift acceleration. and Here, θ represents the proportional and integral gains of the acceleration loop, respectively, and θ is the slope angle. Combined, the closed-loop output at this stage is:

[0137]

[0138] Step S82: After reaching the end position region of the gear shifting and gear synchronization stage, the drive motor speed is adjusted to create a speed difference between the gear and the gear sleeve to complete the gear alignment and eliminate the circumferential backlash between the teeth; wherein, the method of adjusting the drive motor speed includes: constructing an optimal target speed function based on the classical mechanical elastic collision theory and the physical difference between the gear and the gear sleeve backlash.

[0139] when When the shift motor stops operating, the gear shifting synchronization stage begins. This requires adjusting the speed at the drive motor input based on the output shaft's rotational speed and the classical mechanical elastic collision theory between gear sleeves. The specific adjustment method is as follows:

[0140] Based on the structure of the gear sleeve and classical elastic collision theory, the impact kinetic energy of the collision between the two objects is:

[0141]

[0142] Therefore, the impact force can be obtained as:

[0143]

[0144] in, These are the moments of inertia at the ends of the meshing gear sleeves, respectively. Let Δn be the meshing radius of the gear sleeve. Mot_Aim (t) represents the target rotational speed, θ i For overall flexibility.

[0145] As shown in the above formula, the magnitude of the impact force is directly related to the relative rotational speed and relative acceleration of the gear sleeve. In this application, during the gear synchronization stage of the gear change, based on impact theory, the rotational speed of the drive motor is adjusted to reduce the synchronization impact, as shown below:

[0146]

[0147] in, Given the relative circumferential rotational arc length of the gear sleeve, one of the control objectives at this stage is to make... ΔL i For this purpose, the maximum clearance distance between the teeth of the meshing gear sleeve is determined. Another control objective is to minimize the impact force. Therefore, this speed regulation stage can be transformed into the following optimization objective function to find the optimal target rotational speed:

[0148] make:

[0149] Then we can obtain:

[0150]

[0151] st|Δn Mot_Aim (t)|≤Δn upLim ,

[0152] in, As a weighting factor, the longer the duration... The larger and no greater than 1, Δn upLim This represents the upper limit of the rate of change of rotational speed.

[0153] Furthermore, we can 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) * To achieve the optimal target rotational speed, and These are the proportional and integral gain of the speed control, respectively. To minimize the torque required to drive the motor.

[0157] In this embodiment, this application employs a three-closed-loop shift position control that considers the feedforward of the gravitational acceleration component varying with the slope, taking into account the rugged road conditions in the mining area. This improves the robustness of the shift position control during the gear shifting process and optimizes the shift quality to a certain extent. Furthermore, based on the structure of the gear sleeve and classical elastic collision theory, this application constructs an objective function that maximizes displacement and minimizes impact, optimizing the target parameters for drive motor speed regulation during the synchronization phase and reducing the impact during synchronization.

[0158] Furthermore, based on the above embodiments, before the stage of fully engaging the gear and increasing torque, the shifting process control method of the direct-drive automatic transmission without synchronizer motor of this application further includes:

[0159] If the following conditions are met simultaneously during step S80 above, it can be determined that the gear engagement to gear synchronization stage has ended, and the process enters the fully engaged to torque increase stage. The gear synchronization end condition is:

[0160]

[0161] in, The relative circumferential rotational arc length of the gear sleeve. For the torque of the drive motor, To achieve the minimum torque required for the drive motor to rotate, n Mot_Act (t) represents the current speed of the drive motor, n DM_B (t) represents the speed regulation value of the drive motor, Δn Set To determine the threshold for the rotational speed to reach the target value, Δn Mot_Act (t) represents the current speed of the drive motor, Δn Rate The torque of the drive motor is The engine speed when the target gear is i and the automatic transmission output is unloaded. This is the calibration adjustment factor.

[0162] Furthermore, based on the above embodiments, referring to Figure 3 The present application provides a method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor. Specifically, during the stage from full engagement to torque increase, the method includes:

[0163] Step S90: After completing the gear shift synchronization, the transmission enters the stage of full engagement and torque increase. During this stage, the shift position adopts a semi-closed-loop control method, and the shift is engaged by adjusting the drive torque. During the engagement process, torque is simultaneously increased and restored. After the shift position reaches the set position range, the shift lever moves back a set distance towards neutral. Finally, the torque is restored to the torque required by the driver, and the transmission shift process ends. This process adjusts the restored torque value based on the load characteristics of the shift actuator. The shifting method in this application is a DC brushed motor driving a ball screw to drive the shift lever for shifting.

[0164] The method of shifting gears by adjusting the drive torque includes: setting up shifting and retraction position following curves; constructing a physical relationship between the shift motor and the shift position based on the ball screw structure; and outputting the shift motor with a constant duty cycle. The method of increasing torque based on the shift position curve to restore torque also includes: constructing a relationship between the load characteristics of the shift motor and the drive torque of the ball screw structure; and setting a position curve based on the relationship between the load characteristics of the shift motor and the drive torque, as well as the torque, voltage, and motion characteristics of the DC brushed motor, so that the torque of the drive motor gradually increases with the change of the shift position.

[0165] Specifically, step S90 above includes:

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

[0167]

[0168] In the above formula, T e For the electromagnetic torque of the motor, The output torque during the torque recovery period of the drive motor, f1 is the friction coefficient of the gear sleeve meshing surface, and l i θ1 is the distance between the center of the gear sleeve and the center of the leadscrew, θ2 is the leadcrew thread helix angle, 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 is the friction coefficient. T K is the torque constant. E K is the back electromotive force constant, and K T =K E U a I is the armature voltage. a R is the armature current. a L is the total resistance of the circuit. a This is the total inductance of the circuit.

[0169] This application determines the engagement curve of the shift position and obtains the curve of the lead screw angular velocity ω through geometric relationships, i.e., the value during the engagement process. Simultaneously, by employing a constant duty cycle, and based on the physical relationship between the output torque of the shift motor and the drive motor, the output torque of the drive motor can be adjusted. The magnitude of the value is used to make the actual curve of the lead screw angular velocity follow the target curve, thereby completing the torque-driven gear shifting process in this stage. The specific control process is as follows:

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

[0171]

[0172] In the above formula, 's' represents the engagement curve for this shift position, and 'L' is the lead screw. Given 's', the lead screw angular velocity 'ω' can be determined. The shift position curve for this stage is divided into two segments: the engagement curve and the retraction curve, as detailed below:

[0173] The entry curve is:

[0174]

[0175] In the formula P Int_Start1 This refers to the actual shift position value at the start of this phase. For the target position value of gear shifting at this stage, ΔP' is... The difference between the position and the set position for Q+1 cycles, where Q is the set duration of this phase, which is a positive integer.

[0176] The pullback curve is as follows:

[0177]

[0178] In the above formula, For the target location at this stage, P Int_Start2 This refers to the actual shift position value at the start of this phase. For this shift target position value, ΔP” is: The difference between the curve and the approach curve, where b is the shift position reached. The duration of the period is a positive integer.

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

[0180]

[0181] In the formula, Η(ω(t),U a (t) represents the output torque of the drive motor, the angular velocity ω(t) of the shift motor, and the duty cycle of the controller output during this stage. The functional relationship, T Drive (t) represents the torque required by the driver, T Act_Es (t) represents the actual output torque of the drive motor when the shift position reaches the target position, and a represents the actual torque of the drive motor from T. Act_Es (t) Restore to the driver's required torque T Drive The number of cycles required at time (t) is a positive integer, U Total The power supply voltage for the drive motor in the controller is typically 12 or 24V. For this stage, the controller outputs the duty cycle, D. Tj C is the duty cycle when the current is the maximum allowable stall current value. i To adjust the coefficient, Flag Shift_End This indicates the gear engagement is complete; 1 signifies engagement is finished. When the actual torque T of the drive motor... Act (t) and the driver's required torque T Drive When (t) is close, the gear shifting process of the transmission ends.

[0182] In this embodiment, by adopting a method of retracting a set distance after shifting gears, a gap is created between the shift slider and the gear sleeve, reducing the wear of the shift slider under the high-speed rotation of the gear sleeve during gear engagement and improving the life of the transmission assembly.

[0183] Based on the above embodiments, the shifting process control method for a direct-drive automatic transmission without a synchronizer motor in this application addresses the problems of long shifting time, significant power interruption, shifting shock, low engagement success rate, and easy wear of the shift slider in the powertrain of a direct-drive automatic transmission without a synchronizer motor, which lead to driver complaints. Based on the characteristics of direct-drive motors, the shifting time is overlapped with the torque clearing, speed adjustment, and torque increase processes of the drive motor. A closed-loop linkage control method is adopted to reduce the overall shifting time of the transmission. Simultaneously, based on the mechanical structure of the transmission shifting, a shift curve over time is set using theoretical calculations combined with empirical correction. A torque increase method is adopted to simultaneously engage and increase torque, promptly restoring torque, weakening power interruption during shifting, and improving the driver's driving experience. A gear sleeve meshing structure with alternating long and short teeth is used, combined with a target speed adjustment method, and both dynamic target speed rate and dynamic target speed are employed, using a speed-controlled... The cascaded speed rate of the rate feedforward gain and the speed rate and speed adjustment of the speed controller improve the shifting shock problem caused by excessive speed difference or speed change rate during gear sleeve meshing. Furthermore, the reduced tooth overlap during meshing increases the probability of tooth tipping and improves the success rate of gear engagement. In addition, this application employs a three-loop shifting position control based on position, speed, and acceleration feedforward, considering the gradient variation of gravity acceleration. This comprehensively addresses the rugged road conditions in mining areas, improving the robustness of shifting position control during gear shifting and optimizing shifting quality to a certain extent. Based on the structure of the gear sleeve and classical elastic collision theory, this application constructs an objective function that maximizes displacement and minimizes impact, optimizing the target parameters for drive motor speed regulation during the synchronization phase and reducing impact during synchronization. Finally, this application uses a set distance retraction after gear engagement, creating a gap between the shift slider and the gear sleeve, reducing wear on the shift slider under high-speed rotation of the gear sleeve and improving the lifespan of the transmission assembly.

[0184] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0185] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which 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, A method for a gear sleeve meshing structure applied to a gear tooth spacing configuration with alternating long and short teeth includes: The gear shifting process is divided into four stages: the torque reduction stage to neutral, the motor speed adjustment stage to eliminate the idle travel of the gear, the gear engagement stage to gear synchronization, and the gear engagement stage to torque increase. During each stage of the gear shifting process, the system collects current vehicle and transmission status information, as well as relevant sensor information. This status and sensor information includes: accelerator pedal position, brake travel position, actual drive motor torque, shift sensor position for each gear, gradient sensor value, shift motor current, drive motor speed, current gear, target gear, output shaft speed, and shifting process status, in order to control the gear shifting process. During the torque reduction to neutral shift stage, the shift is performed based on the actual torque change, combined with estimated time feedforward, open-loop and closed-loop control, and different operating conditions. During the motor speed regulation phase until the idle travel of the gear engagement is eliminated, a dynamic target speed rate and a dynamic target rotational speed are used in combination with a speed regulation method that crosses the target speed. A cascaded speed rate with feedforward gain and a speed controller are used to adjust the speed rate and rotational speed for speed and rotational synchronization, including the speed regulation phase: S71: During the preparation stage before speed and rotational speed synchronization, dynamic target rotational speed and proportional parameters are used for control; S72: During the speed and rotational speed synchronization stage, a dynamic target speed rate and a dynamic target rotational speed are adopted. A cascaded speed rate with speed rate feedforward gain and a speed controller are used to adjust the speed rate and rotational speed for speed synchronization. The specific steps during the shifting and gear synchronization phase include: S81: The three-closed-loop control method of position, velocity and acceleration, which takes into account the gravity acceleration component that changes with the slope, follows the set gear engagement curve. If the gear is hit, the shift position will retract the set stroke towards neutral and then continue to follow the set gear engagement curve to engage gear. S82: After reaching the end position of the gear shifting and gear matching synchronization stage, the drive motor speed is adjusted to create a speed difference between the gear and the gear sleeve to complete the gear matching and eliminate the circumferential backlash between the teeth; wherein, the method of adjusting the drive motor speed includes: constructing an optimal target speed function based on the classical mechanical elastic collision theory and the physical difference between the gear and the gear sleeve backlash.

2. The method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor as described in claim 1, characterized in that, Before the torque reduction to neutral shift stage, the method further includes: S10: Monitor the status of the gear shifting process. If the gear shifting starts, record the gear shifting start torque and obtain the basic target speed of the drive motor based on the current gear, the target gear, and the output shaft speed. S20: Determine the torque reduction rate based on the current drive motor speed, actual drive motor torque, throttle position, and brake stroke. S30: Calculate the expected 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 described in claim 2, characterized in that, During the torque reduction and neutral shift phase, the shifting process, based on actual torque changes combined with estimated time feedforward, open-loop and closed-loop control, and different operating conditions, includes: S40: In the first stage of neutral shifting, the shifting motor intermittently shifts gears using an open-loop duty cycle, while simultaneously monitoring the current and actual torque of the shifting motor. S50: In the second stage of neutral shift, the shift position sensor value and actual torque are collected, the torque reduction rate is calculated, and the shift position sensor change rate is kept constant to shift gear. With the constant shift position sensor change rate as the control target, the output duty cycle of the shift motor is adjusted in real time using a closed-loop control method. S60: In the third stage of shifting to neutral, the shift position sensor value and the actual torque value of the drive motor are collected, and the shift motor duty cycle is output using a 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 described in claim 1, characterized in that, Before the motor speed is adjusted to the stage of eliminating idle travel during gear engagement, the method further includes: A1: Determine whether the current gear and the target gear share the same shift actuator; A2: If a single shift actuator is used, determine whether the actual position of disengaging the gear is within the range of the lower limit tooth position and the upper limit tooth position; if the actual position of disengaging the gear is within the range of the lower limit tooth position and the upper limit tooth position, the torque reduction to neutral shift stage ends. 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 stage ends, and the motor speed regulation to eliminate shift travel stage begins. If the shift position is not within the neutral center position threshold, continue executing A1, A2, and 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 described in claim 4, characterized in that, In the stage where the motor speed is adjusted to eliminate the idle travel during gear engagement, the method further includes a stage for eliminating the axial idle travel during gear engagement: S73: Uses nonlinear single-class proportional parameter control; S74: Employs a periodic constant duty cycle, fixed time period, and intermittent conservative control method, including a shift head retraction process; wherein, the shift head retraction process is as follows: if S71 and S72 of the speed adjustment stage are completed before or simultaneously with this stage, then directly enter the gear engagement to gear shift synchronization stage; otherwise, after the axial position of the gear engagement reaches the set point, a small-amplitude set stroke retraction is performed to retract the set stroke.

6. The method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor as described in claim 1, characterized in that, Before the complete engagement of the gear and the torque increase phase, the method further includes: If the conditions for ending the gear shift synchronization are met, then the gear shift to gear shift synchronization stage is considered complete, and the process enters the stage from full gear engagement to torque increase. The conditions for ending the gear shift synchronization are: ； in, The relative circumferential rotational arc length of the gear sleeve. For the torque of the drive motor, To achieve the minimum torque required for the drive motor to rotate, This is the current drive motor speed. This is the speed control value for the drive motor. To determine the threshold for the rotational speed to reach the target value, This represents the current speed of the drive motor. The torque of the drive motor is The target gear is The speed rate of a transmission with no load at the output end of a geared or automatic transmission. This is the calibration adjustment factor.

7. The method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor as described in claim 6, characterized in that, During the stage from full gear engagement to torque increase, the method includes: A semi-closed-loop control method is adopted, and gear engagement is achieved through drive torque adjustment; While shifting gears, torque is increased based on the shift position curve to restore torque. Once the shift position reaches the set position range, the shift lever retracts a set distance towards neutral, and then the torque is restored to the required torque. When restoring the torque to the required torque, the magnitude of the restored torque value is adjusted based on the load characteristics of the shift actuator.

8. The method for controlling the shifting process of a direct-drive automatic transmission without a synchronizer motor as described in claim 7, characterized in that, The method of shifting gears by adjusting the drive torque includes: setting the shifting and retraction position following curves; constructing the physical relationship between the shifting motor and the shifting position based on the ball screw structure; and outputting the shifting motor with a constant duty cycle. The method of increasing torque based on shift position curve to restore torque also includes: constructing the relationship between the load characteristics of the shift motor and the drive torque of the ball screw structure; and setting a position curve according to the relationship between the load characteristics of the shift motor and the drive torque, as well as the torque, voltage and motion characteristics of the DC brushed motor, so that the torque of the drive motor gradually increases with the change of shift position.

Images