Gear shifting control method and system of electric commercial vehicle, medium and electric commercial vehicle

Abstract

The invention discloses a gear shifting control method and system of an electric commercial vehicle, a medium and the electric commercial vehicle. The method comprises the steps that if it is detected that the electric commercial vehicle is in an emergency braking working condition, a target drive axle to be controlled is determined, the torque of the target drive axle is controlled to be reduced by referring to the vehicle speed of the electric commercial vehicle, and a corresponding gear shifting hub is arranged in a neutral gear; wherein the target drive axle is any drive axle in double drive axles of the electric commercial vehicle; when the gear shifting hub corresponding to the target drive axle is in the neutral gear, the drive motor of the target drive axle is switched from the torque control mode to the rotating speed control mode; in the rotating speed control mode, whether the target drive axle executes dynamic gear shifting or static gear shifting is judged according to the rotating speed of the output shaft, and the corresponding target rotating speed is determined; the driving motor of the target driving axle is controlled to adjust the speed according to the target rotating speed, and whether the driving motor of the target driving axle meets the corresponding gear shifting synchronization condition or not is judged; and if yes, the gear shifting hub corresponding to the target drive axle is changed from the neutral gear to the target gear.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle technology, and in particular to a shift control method, system, medium, and electric commercial vehicle for electric commercial vehicles. Background Technology

[0002] Driven by both the rapid iteration of the global new energy vehicle industry and the green transformation of the commercial vehicle sector, electric commercial vehicles are experiencing a continuous surge in market demand due to their core advantages of low emissions and high economic efficiency. To meet the power output requirements of electric commercial vehicles under complex operating conditions such as heavy loads and hill climbing, the dual-axle, dual-motor power configuration has become the mainstream technical choice. This structure, with two motors driving the middle and rear axles respectively, effectively improves the overall vehicle's power performance and load-bearing capacity. Meanwhile, to adapt to heavy-duty transportation scenarios, electric commercial vehicles generally adopt a high-ratio design for their gear shifting mechanisms to achieve high torque output at low speeds, ensuring driving stability and load-bearing efficiency.

[0003] However, in the special condition of emergency braking, electric commercial vehicles face prominent technical bottlenecks: emergency braking requires the vehicle to transition from a dynamic state to a stop state in a short period of time. At this time, the high gear ratio design of electric commercial vehicles will cause the output shaft speed to change drastically, and the speed fluctuation amplitude and rate are significantly higher than those under normal driving conditions. Furthermore, the independent drive characteristics of dual axles and dual motors further increase the difficulty of controlling speed synchronization during gear shifting, making it difficult for the speeds of the drive motor and the shifting mechanism to match quickly. Impacts and interference are easily generated during gear meshing, ultimately leading to frequent gear shifting failures or gear grinding. This not only affects driving safety and shifting smoothness, but also aggravates the wear of transmission components and shortens the service life of the entire vehicle. Summary of the Invention

[0004] To address or partially resolve the technical problem of frequent gear shifting failures or gear grinding caused by the dual-axle, dual-motor structure of electric commercial vehicles, this invention provides a gear shifting control method, system, medium, and electric commercial vehicle for electric commercial vehicles. During emergency braking, the technical solution of this invention first dynamically determines the target drive axle to avoid electronic control command conflicts and gear overload caused by synchronous gear shifting of the dual axles. Then, combined with precise speed control to reduce torque and neutral shifting, the drive motor smoothly switches to speed mode without load constraints. Simultaneously, based on the output shaft speed, it distinguishes between dynamic and static gear shifting scenarios and matches differentiated control strategies, significantly improving speed matching efficiency and accuracy. Finally, through closed-loop determination of gear shifting synchronization conditions, it ensures that the speed is fully matched before executing the gear engagement action, reducing gear meshing impact and wear at the source. This effectively reduces the failure rate and gear grinding risk of emergency braking gear shifting under the dual-axle, dual-motor structure, significantly improving gear shifting safety, smoothness, and system reliability.

[0005] To address the aforementioned technical problems, a first aspect of the present invention discloses a gear shifting control method for an electric commercial vehicle, the method comprising: If the electric commercial vehicle is detected to be in an emergency braking condition, the target drive axle to be controlled is determined, and the torque of the target drive axle is reduced with reference to the vehicle speed of the electric commercial vehicle, and the corresponding shift hub is placed in neutral; wherein, the target drive axle is either of the two drive axles of the electric commercial vehicle; the shift hub of the target drive axle being placed in neutral indicates that the drive motor of the target drive axle has switched from torque control mode to speed control mode; In the speed control mode, the target drive axle is determined to perform dynamic or static shifting based on the output shaft speed, and the corresponding target speed is determined accordingly. The drive motor of the target drive axle is controlled to adjust its speed according to the target speed, and it is determined whether the drive motor of the target drive axle meets the corresponding shift synchronization conditions. If the conditions are met, the shift hub corresponding to the target drive axle is shifted from neutral to the target gear.

[0006] Optionally, if the electric commercial vehicle is detected to be in an emergency braking condition, determining the target drive axle to be controlled specifically includes: If the electric commercial vehicle is detected to be in an emergency braking condition, check whether there is a signal indicating that the middle axle has completed the gear shift action. If not, the middle bridge is determined to be the target drive bridge; If so, confirm that the rear axle is the target drive axle.

[0007] Optionally, the step of reducing the target drive axle torque and placing the corresponding shift hub in neutral, in reference to the vehicle speed control of the electric commercial vehicle, specifically includes: Monitor the actual speed of the electric commercial vehicle; If the actual vehicle speed decreases to the set vehicle speed calibration value, the torque of the target drive axle is reduced. If the torque of the target drive axle decreases to a set torque value, the shift hub corresponding to the target drive axle is placed in neutral.

[0008] Optionally, determining whether the target drive axle performs dynamic or static shifting based on the output shaft speed specifically includes: If the absolute value of the output shaft speed is below the set speed and not 0, then the target drive axle performs the above dynamic shifting. If the output shaft speed is 0, the target drive axle performs the static shift.

[0009] Optionally, if the target drive axle performs the dynamic shift, determining the corresponding target speed specifically includes: according ton target.1 = n base.1 +Δ n 1× k 1. Determine the target rotational speed; in, n target.1 This indicates the target speed corresponding to the dynamic gear shift; n base.1 This indicates the base speed corresponding to the dynamic shifting. n base.1 = n output × i target , n output This indicates the output shaft speed. i target Indicates the gear ratio of the target gear; Δ n 1 represents the motor speed compensation coefficient corresponding to the dynamic shifting, which is obtained by referring to the brake pedal travel and slope signal from a table; k 1 represents the motor direction coefficient corresponding to the dynamic shift, which is obtained by referring to the direction of the output shaft speed. If the direction of the output shaft speed is positive, k 1=1, if the direction of the output shaft rotation speed is negative, k 1 = -1; If the target drive axle performs the static gear shift, determining the corresponding target speed specifically includes: according to n target.2 = n base.2 × k 2. Determine the target speed corresponding to the static gear shift; in, n target.2 This indicates the target speed corresponding to the static gear shift; n base.2 The base speed corresponding to the static gear shift is obtained by referring to the motor temperature; k 2 represents the motor direction coefficient corresponding to the static shift, which is determined by the motor direction coefficient of the previous cycle.

[0010] Optionally, before controlling the drive motor of the target drive axle to adjust its speed according to the target rotational speed, the method further includes: The torque limit is adjusted according to the target speed; wherein the torque limit for dynamic shifting is greater than the torque limit for static shifting.

[0011] Optionally, the shift synchronization condition is specifically the shift synchronization condition corresponding to the dynamic shift, or the shift synchronization condition corresponding to the static shift; The shifting synchronization condition corresponding to the dynamic shifting is: the difference between the actual speed of the drive motor of the target drive axle and the target speed is within a preset speed difference range, and the rate of change of the speed difference between the two is less than or equal to a first rate of change, and is delayed by a first preset delay time; wherein, the preset speed difference range is set with reference to the target gear transmission ratio and the speed difference of the engaging gear. The shift synchronization condition corresponding to the static shift is as follows: the difference between the actual speed of the drive motor of the target drive axle and the target speed is lower than the set speed difference, and the rate of change of the speed difference is less than or equal to the second rate of change, and there is a second set delay time; the set speed difference is lower than the minimum value of the preset speed difference range, and the second rate of change is less than the first rate of change.

[0012] A second aspect of the present invention discloses a shift control system for an electric commercial vehicle, the system comprising: The first control module is used to determine the target drive axle to be controlled if the electric commercial vehicle is detected to be in an emergency braking condition, reduce the torque of the target drive axle with reference to the vehicle speed of the electric commercial vehicle, and put the corresponding shift hub in neutral; wherein, the target drive axle is either of the two drive axles of the electric commercial vehicle; the shift hub of the target drive axle being put in neutral indicates that the drive motor of the target drive axle has switched from torque control mode to speed control mode; The judgment module is used to determine whether the target drive axle is performing dynamic shifting or static shifting based on the output shaft speed in the speed control mode, and to determine the corresponding target speed. The second control module is used to control the drive motor of the target drive axle to adjust its speed according to the target speed, and to determine whether the drive motor of the target drive axle meets the corresponding shift synchronization conditions. The switching module is used to, if the conditions are met, switch the shift hub corresponding to the target drive axle from neutral to the target gear.

[0013] A third aspect of the present invention discloses a computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the steps of the above-described method.

[0014] A fourth aspect of the present invention discloses an electric commercial vehicle, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the above-described method.

[0015] Through one or more technical solutions of the present invention, the present invention has the following beneficial effects or advantages: The technical solution of this invention, if the electric commercial vehicle is detected to be in an emergency braking condition, firstly identifies the target drive axle to avoid electronic control command conflicts and sudden increases in gear load caused by simultaneous shifting actions of both axles; then, by combining precise control of the target drive axle's torque reduction timing and neutral shifting action with vehicle speed, the drive motor smoothly switches from torque mode to speed mode under no load constraints, eliminating the impact of load disturbances on speed regulation accuracy; simultaneously, based on the output shaft speed, it distinguishes between dynamic and static shifting scenarios, matching differentiated torque limits and target speed calculation strategies, which can significantly improve the efficiency and accuracy of speed matching; finally, through closed-loop determination of shifting synchronization conditions, it ensures that the drive motor speed and the target gear speed are fully matched before the gear engagement action is performed, fundamentally reducing the impact and wear during gear meshing, effectively reducing the failure rate of emergency braking shifting and the risk of gear breakage in the dual-axle dual-motor structure, and significantly improving the shifting safety, smoothness, and system reliability of electric commercial vehicles under emergency braking conditions.

[0016] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A flowchart of a gear shifting control method for an electric commercial vehicle according to an embodiment of the present invention is shown; Figure 2 A flowchart illustrating an overall process for a gear shifting control method for an electric commercial vehicle according to an embodiment of the present invention is shown. Figure 3 A schematic diagram of a shift control system for an electric commercial vehicle according to an embodiment of the present invention is shown. Detailed Implementation

[0018] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0019] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0020] Firstly, such as Figure 1 As shown, the gear shifting control method for electric commercial vehicles provided in this embodiment of the invention includes at least the following steps: S101, if the electric commercial vehicle is detected to be in an emergency braking condition, the target drive axle to be controlled is determined, the torque of the target drive axle is reduced with reference to the speed of the electric commercial vehicle, and the corresponding shift hub is placed in neutral.

[0021] Commercial electric vehicles employ a dual-drive axle, dual-motor drive layout with a middle axle and a rear axle. The middle and rear axles are two independent drive axles, each equipped with a dedicated drive motor, shift motor, and shift hub, forming two symmetrical and independent axle-based power shifting mechanisms. Furthermore, the EDCU (Electronic Drive Control Unit), as the core of the vehicle's shifting and power control, establishes a communication connection with the MTCU (Motor Control Unit). The MTCU, as the direct control core for all motors, integrates two independent control channels, one corresponding to the middle axle and the other to the rear axle. Each channel simultaneously connects to one drive motor and one shift motor on the corresponding axle, independently issuing speed adjustment, shifting, and mode switching commands to the motors on each axle, forming two independent control chains. After receiving control commands from the EDCU, the MTCU directly and precisely controls the drive motors and shift motors of each axle. The drive motors provide driving power to the corresponding axle, and the shift motors are mechanically connected to the shift hubs of the corresponding axle. They are the actuators that drive the shift hubs to complete the mechanical actions of shifting gears. The shift hubs, as the core actuators for shifting gears on each axle, cooperate with the mode switching and speed adjustment actions of the drive motors of the corresponding axle to complete gear shifting. This forms a structural relationship of EDCU overall control coordination, MTCU sub-bridge control, and linkage and cooperation between the drive motors and shift motors of both axles.

[0022] If a brake pedal is detected and the accelerator pedal opening is 0, it indicates that the electric commercial vehicle is in an emergency braking condition.

[0023] The target drive axle is any one of the dual drive axles of the electric commercial vehicle. The target drive axle in the shift process can be determined as the middle axle or the rear axle based on the actual situation.

[0024] If the electric commercial vehicle is detected to be in an emergency braking condition, since the electric commercial vehicle has a dual-drive axle dual-motor drive layout and needs to execute a fixed shifting sequence of the middle axle first and the rear axle last, it is necessary to further detect whether there is a signal indicating that the middle axle has shifted in place, that is, to detect whether the middle axle has shifted in place; if not, it means that the middle axle has not shifted, and the middle axle is determined to be the target drive axle; if so, it means that the middle axle has shifted, and the rear axle is determined to be the target drive axle.

[0025] It is worth noting that the middle and rear axles perform the same steps in the subsequent gear shifting operation, both executing S102~S104, so they will be introduced together later.

[0026] After identifying the target drive axle to be controlled, the torque of the target drive axle is reduced with reference to the speed control of the electric commercial vehicle, and the corresponding shift hub is placed in neutral.

[0027] In the specific implementation process, the actual speed of the electric commercial vehicle is monitored; if the actual speed decreases to the set speed calibration value, for example, to 5 km / h, the torque of the target drive axle is reduced; if the torque of the target drive axle decreases to the set torque value, for example, to below 5 NM, the shift hub corresponding to the target drive axle is placed in neutral.

[0028] Specifically, if the actual speed of the electric commercial vehicle is detected to drop to 5 km / h, a corresponding torque reduction strategy is matched according to the real-time speed of the electric commercial vehicle. The drive motor of the target drive axle is precisely controlled to gradually reduce the output torque to below 5 NM. At the same time, an action command is sent to the shift motor of the axle to drive the shift hub to complete the disengagement, that is, to switch the gearbox from the current driving gear of the vehicle to neutral and keep it stably in the neutral position.

[0029] In this context, the shift hub corresponding to the target drive axle being in neutral indicates that the drive motor of the target drive axle has switched from torque control mode to speed control mode. In torque control mode, the purpose of controlling the drive motor of the target drive axle is to output power to drive the commercial electric vehicle. In speed control mode, the purpose of controlling the drive motor of the target drive axle is to adjust to the target speed, rather than to provide power.

[0030] Specifically, the shift hub corresponding to the target drive axle is placed in neutral, cutting off the hard connection between the drive motor corresponding to the target drive axle, the gearbox output shaft, and the wheels. At this time, even if the drive motor adjusts the speed in speed control mode, its rotation will not be transmitted to the wheels through the gearbox, that is, it will not provide power. This allows the subsequent speed adjustment to be carried out in an environment without gear meshing and without power interference, laying the foundation for precise control of the target speed and avoiding gear grinding.

[0031] S102, in the speed control mode, the target drive axle is determined to perform dynamic or static shifting based on the output shaft speed, and the corresponding target speed is determined.

[0032] During the judgment process, if the absolute value of the output shaft speed is below the set speed and is not 0, for example, if the absolute value of the output shaft speed is ≤5r / min and is not 0, then the target drive axle performs the above dynamic shifting; if the output shaft speed is 0, then the target drive axle performs the static shifting.

[0033] Dynamic shifting and static shifting each determine the target speed differently.

[0034] If the target drive axle performs the dynamic shift, according to n target.1 = n base.1 +Δ n 1× k 1. Determine the target rotational speed.

[0035] in, n target.1 This indicates the target speed corresponding to the dynamic gear shift; n base.1 This indicates the base speed corresponding to the dynamic shifting. n base.1 = n output × i target , n output This represents the output shaft speed. When the direction of the output shaft speed is positive... n output It is a positive value; it is used when the output shaft speed is in the negative direction. n output It is a value with a negative sign. i target Indicates the gear ratio of the target gear; Δ n 1 represents the motor speed compensation coefficient corresponding to the dynamic shifting, which is obtained by referring to the brake pedal travel and slope signal from a table; k 1 represents the motor direction coefficient corresponding to the dynamic shift, which is obtained by referring to the direction of the output shaft speed. If the direction of the output shaft speed is positive, k 1=1, if the direction of the output shaft rotation speed is negative, k 1 = -1.

[0036] Specifically, the target engine speed corresponding to dynamic shifting is obtained as follows: Multiply the output shaft speed by the gear ratio of the target gear to calculate the base speed corresponding to dynamic gear shifting. The calculation process is as follows: n base.1 = n output × i target For example, the target gear ratio is the gear ratio of 1st gear.

[0037] Based on the brake pedal travel and gradient signal, the motor speed compensation coefficient corresponding to dynamic gear shifting is obtained by looking up the table.

[0038] During emergency braking, the output shaft speed changes rapidly when the shift motor controls the shift drum to shift gears. Therefore, it is necessary to compensate for the speed change of the output shaft during the shift motor's control of the shift drum to shift gears, to prevent shift failure or gear grinding. The brake pedal travel and gradient signals at this time are shown in Table 1.

[0039]

[0040] Table 1 Dynamic shifting speed compensation table for drive motor under emergency braking conditions Furthermore, the setting of the motor speed compensation coefficient needs to take into account the motor direction. Therefore, the motor direction coefficient corresponding to dynamic shifting is determined, which is determined by the direction of the output shaft speed. If the output shaft speed is in the positive direction, the motor direction coefficient corresponding to dynamic shifting is 1; if the output shaft speed is in the negative direction, the motor direction coefficient corresponding to dynamic shifting is -1.

[0041] Once the target speed, motor speed compensation coefficient, and motor direction coefficient corresponding to dynamic gear shifting are obtained, the target speed corresponding to dynamic gear shifting can be calculated according to the aforementioned formula.

[0042] If the target drive axle performs the static shift, according to n target.2 = n base.2 × k 2. Determine the target speed corresponding to static gear shifting.

[0043] in, n target.2 This indicates the target speed corresponding to the static gear shift; n base.2 The base speed corresponding to the static gear shift is obtained by referring to the motor temperature; k 2 represents the motor direction coefficient corresponding to the static shift, which is determined by the motor direction coefficient of the previous cycle.

[0044] The base speed corresponding to the static shift is set by the motor temperature to avoid high shifting resistance at low temperatures, which could lead to shifting failure. See Table 2 for details.

[0045]

[0046] Table 2 Basic Speed ​​Settings for Static Shifting under Emergency Braking Conditions of Drive Motor Furthermore, the target speed for static shifting also needs to consider the motor direction. Therefore, the motor direction coefficient for static shifting is determined by the motor direction coefficient of the previous cycle. If the output shaft speed of the previous cycle is in the positive direction, the motor direction coefficient for static shifting is 1; if the output shaft speed of the previous cycle is in the negative direction, the motor direction coefficient for static shifting is -1. By controlling the target speed for static shifting through the direction setting of the output shaft speed, the speed adjustment time can be shortened and the probability of gear grinding can be reduced when the vehicle transitions from dynamic braking or coasting to static shifting.

[0047] For example, if a commercial electric vehicle's output shaft speed drops from 2 r / min in the positive direction (dynamic shifting, k=1) to 0 (entering static shifting) during emergency braking: At a speed of 2 r / min: this is dynamic gear shifting, and the motor direction coefficient for dynamic gear shifting is 1; When the speed drops to 0: enter static shifting, with no positive or negative direction, directly maintaining the motor direction coefficient of 1 from the previous cycle. The target speed for static shifting is... n target.2 = n base.2 ×1.

[0048] If a commercial electric vehicle's output shaft speed drops from 3 r / min in the negative direction (dynamic shifting, k=-1) to 0 (entering static shifting) during emergency braking: At a speed of 3 r / min: dynamic shifting, the motor direction coefficient for dynamic shifting is -1; When the speed drops to 0: Static shifting, maintaining the motor direction coefficient of the previous cycle at -1, the target speed for static shifting. n target.2 = n base.2 × (-1).

[0049] It is worth noting that the motor direction considerations for dynamic and static shifting are continuous, not separate. Ultimately, they are all aimed at ensuring a precise match between the motor speed and the rotation state of the output shaft, thus avoiding shifting problems caused by sudden changes in direction.

[0050] S103, control the drive motor of the target drive axle to adjust its speed according to the target speed, and determine whether the drive motor of the target drive axle meets the corresponding shift synchronization conditions.

[0051] In this control logic, to ensure that the speed adjustment action of the target drive axle's drive motor in speed control mode is adapted to the shifting condition of emergency braking and to guarantee the response speed and accuracy of speed adjustment, before controlling the drive motor of the target drive axle to adjust its speed according to the target speed, the corresponding torque limit needs to be adjusted according to the target speed. Specifically, because the output shaft still has a speed during dynamic shifting and the speed adjustment target is larger, a higher torque limit is required to provide power support for the motor's rapid speed adjustment. During static shifting, the output shaft speed is 0 and the speed adjustment target is smaller, so a lower torque limit can meet the speed fine-tuning requirements and avoid speed overshoot. Therefore, the torque limit for dynamic shifting is greater than the torque limit for static shifting.

[0052] During the speed adjustment process, it is necessary to simultaneously determine whether the drive motor of the target drive axle meets the shift synchronization conditions of the emergency braking condition, so as to execute the subsequent shift operation.

[0053] Specifically, the shift synchronization condition refers to either the shift synchronization condition corresponding to dynamic shifting or the shift synchronization condition corresponding to static shifting.

[0054] The shift synchronization condition corresponding to the dynamic shift is: the difference between the actual speed of the drive motor of the target drive axle and the target speed is within a preset speed difference range, and the rate of change of the speed difference is less than or equal to a first rate of change, and is delayed by a first preset delay time.

[0055] Specifically, the actual speed of the drive motor of the target drive axle is obtained, and the speed difference is obtained by combining it with the target speed. If the speed difference is within the preset speed difference range: 135rpm-280rpm, and the rate of change of the speed difference is less than or equal to the first rate of change: 3000rpm / s, and the first set delay time is 0.05s, then the shift synchronization condition corresponding to dynamic shifting is met.

[0056] The preset speed difference range is set with reference to the target gear ratio and the speed difference of the engaging gear. It is obtained by multiplying the target gear ratio and the speed difference of the engaging gear. For example, if the speed difference of the engaging gear is 3rpm-8rpm and the first gear ratio is 45, then the preset speed difference range is 135rpm-280rpm.

[0057] If the shift synchronization conditions corresponding to dynamic shifting are not met, the current speed regulation action is maintained and after a delay time, the drive motor of the middle bridge is checked again to see if the shift synchronization conditions corresponding to dynamic shifting are met. If they are still not met, the current synchronization judgment process is exited, the current speed regulation action is terminated, and the target speed corresponding to dynamic shifting is recalculated.

[0058] The shift synchronization condition corresponding to the static shift is as follows: the difference between the actual speed of the drive motor of the target drive axle and the target speed is lower than the set speed difference, and the rate of change of the speed difference is less than or equal to the second rate of change, and there is a second set delay time; the set speed difference is lower than the minimum value of the preset speed difference range, and the second rate of change is less than the first rate of change.

[0059] Specifically, the actual speed of the drive motor of the target drive axle is obtained, and the speed difference is obtained by combining it with the target speed. If the speed difference is lower than the set speed difference by 10 rpm / s, and the rate of change of the speed difference is less than or equal to the second rate of change of 100 rpm / s, and the second set delay time is 0.05s, then the shift synchronization condition corresponding to static shifting is met.

[0060] If the shift synchronization conditions corresponding to static shifting are not met, the current speed regulation action is maintained and after a delay time, the drive motor of the middle bridge is checked again to see if the shift synchronization conditions corresponding to static shifting are met. If they are still not met, the current synchronization judgment process is exited, the current speed regulation action is terminated, and the target speed corresponding to dynamic static shifting is recalculated.

[0061] S104, if satisfied, change the shift hub corresponding to the target drive axle from neutral to the target gear.

[0062] Specifically, if the target drive axle performs dynamic shifting, when the drive motor of the target drive axle meets the shifting synchronization condition corresponding to the dynamic shifting, the shifting motor corresponding to the target drive axle is controlled to shift the shifting hub from neutral to the target gear, such as first gear.

[0063] It should be noted that during the shifting motor control of the shifting gear, the torque of the drive motor needs to be limited to prevent excessive torque from causing shifting shock. See Table 3 for the torque limit of the drive motor during shifting of the middle axle.

[0064]

[0065] Table 3 shows the torque limits of the drive motor during gear shifting in the axle. Specifically, if the target drive axle performs static shifting, and the drive motor of the target drive axle meets the shifting synchronization condition corresponding to the static shifting, then the shifting motor corresponding to the target drive axle is controlled to shift the shifting hub from neutral to the target gear, such as first gear.

[0066] It should be noted that during the shifting motor control of the gear shifting gear, the torque of the drive motor needs to be limited to prevent excessive torque from causing shifting shock.

[0067] Furthermore, if the target drive axle is the middle axle, after the shift hub corresponding to the middle axle shifts from neutral to the target gear, a middle axle shift action completion signal is generated to facilitate switching to the rear axle shift operation. The rear axle shift operation also executes S102-S104, so it will not be described in detail here.

[0068] To provide a complete overview of the shift control in this technical solution, please refer to the following: Figure 2 This is the overall flowchart of gear shift control for electric commercial vehicles.

[0069] S201, Emergency braking condition triggered by an electric commercial vehicle.

[0070] If a brake pedal is detected and the accelerator pedal opening is 0, it indicates that the electric commercial vehicle has triggered an emergency braking condition.

[0071] S202: Confirm control of the middle bridge and issue a downshift request to the middle bridge.

[0072] S203: Based on the real-time speed of the electric commercial vehicle, the drive motor of the middle axle is controlled to reduce the output torque, and the shift motor of the middle axle is driven to shift the middle axle's shift hub from the current 2nd gear to neutral.

[0073] S204: The drive motor of the middle bridge enters the speed control mode.

[0074] S205: Determine whether the target drive axle performs dynamic or static shifting based on the output shaft speed.

[0075] If it is dynamic shifting, execute S206a~S212.

[0076] S206a, calculate the target speed corresponding to dynamic gear shifting.

[0077] S207a, the drive motor of the middle bridge adjusts its speed according to the target speed corresponding to the dynamic shift.

[0078] S208a determines whether the drive motor of the middle bridge meets the shift synchronization conditions corresponding to dynamic shifting.

[0079] If the synchronization condition is not met, execute S209a to maintain the current speed regulation action and wait for the delay time, and execute S210a to check whether the drive motor of the middle bridge meets the shift synchronization condition corresponding to dynamic shifting. If it is still not met, execute S211a to exit the current synchronization judgment process, terminate the current speed regulation action, and return to execute S206a.

[0080] If the synchronization conditions of S208a or S210a are met, execute S212 to control the middle bridge shift motor to perform the shifting action.

[0081] Of course, if it is a static shift, execute S206b~S212.

[0082] S206b, calculate the target speed corresponding to static gear shift.

[0083] In S207b, the drive motor of the middle bridge adjusts its speed according to the target speed corresponding to the static shift.

[0084] S208b determines whether the drive motor of the middle bridge meets the shift synchronization conditions corresponding to static shifting.

[0085] If the synchronization condition is not met, execute S209b to maintain the current speed regulation action and wait for the delay time, and execute S210b to check again whether the drive motor of the middle bridge meets the shift synchronization condition corresponding to static shifting. If it still does not meet the condition, execute S211b to exit the current synchronization determination process and terminate the current speed regulation action. Return to execute S206b.

[0086] If the synchronization conditions of S208b or S210b are met, execute S212 to control the middle bridge shift motor to perform the shifting action.

[0087] After executing S212, S213 is executed further to determine whether the middle axle shift is complete. That is, whether there is a signal indicating that the middle axle shift action has been completed.

[0088] If the middle axle shift is not completed, switch to S203 and repeat the middle axle shift operation until the middle axle shift is completed.

[0089] If completed, the middle axle is replaced with the rear axle, and the process is repeated in step S202 until the rear axle shift is completed, at which point the emergency braking condition shift is complete.

[0090] The above describes the shift control method for electric commercial vehicles based on this technical solution. To address the frequent shift failures or gear grinding issues caused by the dual-axle, dual-motor structure of electric commercial vehicles, the target drive axle is first identified to avoid electronic control command conflicts and sudden increases in gear load caused by simultaneous shifting actions of both axles. Then, by precisely controlling the timing of torque reduction and neutral shifting of the target drive axle based on vehicle speed, the drive motor smoothly switches from torque mode to speed mode under no-load constraints, eliminating the impact of load disturbances on speed regulation accuracy. Simultaneously, by differentiating dynamic and static shifting scenarios based on output shaft speed, differentiated torque limits and target speed calculation strategies are matched, significantly improving the efficiency and accuracy of speed matching. Finally, through closed-loop determination of shift synchronization conditions, the drive motor speed is ensured to be fully matched with the target gear speed before the gear engagement action is performed, fundamentally reducing the impact and wear during gear meshing. This effectively reduces the failure rate of emergency braking shifting and the risk of gear grinding under the dual-axle, dual-motor structure, significantly improving the shifting safety, smoothness, and system reliability of electric commercial vehicles under emergency braking conditions.

[0091] Secondly, based on the same inventive concept as the gear shifting control method for electric commercial vehicles provided in the first aspect of the embodiments described above, the present invention also provides a gear shifting control system for electric commercial vehicles, see below. Figure 3 The system includes: The first control module 301 is used to determine the target drive axle to be controlled if the electric commercial vehicle is detected to be in an emergency braking condition, reduce the torque of the target drive axle with reference to the vehicle speed of the electric commercial vehicle, and put the corresponding shift hub in neutral; wherein, the target drive axle is either of the two drive axles of the electric commercial vehicle; the shift hub of the target drive axle being put in neutral indicates that the drive motor of the target drive axle has switched from torque control mode to speed control mode; The judgment module 302 is used to determine whether the target drive axle is performing dynamic shifting or static shifting based on the output shaft speed in the speed control mode, and to determine the corresponding target speed. The second control module 303 is used to control the drive motor of the target drive axle to adjust its speed according to the target speed, and to determine whether the drive motor of the target drive axle meets the corresponding shift synchronization conditions. The switching module 304 is used to switch the shift hub corresponding to the target drive axle from neutral to the target gear if the conditions are met.

[0092] It should be noted that the specific way each module performs its operation in the shift control system for electric commercial vehicles provided in the embodiments of the present invention has been described in detail in the method embodiments provided in the first aspect above. The specific implementation process can be referred to the method embodiments provided in the first aspect above, and will not be described in detail here.

[0093] Thirdly, based on the same inventive concept as the gear shifting control method for electric commercial vehicles provided in the first aspect of the embodiments described above, the present invention also discloses a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of any of the methods described above.

[0094] Fourthly, based on the same inventive concept as the gear shifting control method for electric commercial vehicles provided in the first aspect of the embodiments described above, the present invention also discloses an electric commercial vehicle, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of any of the methods described above.

[0095] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0096] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A shift control method for an electric commercial vehicle, characterized in that, The method includes: If the electric commercial vehicle is detected to be in an emergency braking condition, the target drive axle to be controlled is determined, and the torque of the target drive axle is reduced with reference to the vehicle speed of the electric commercial vehicle, and the corresponding shift hub is placed in neutral; wherein, the target drive axle is either of the two drive axles of the electric commercial vehicle; the shift hub of the target drive axle being placed in neutral indicates that the drive motor of the target drive axle has switched from torque control mode to speed control mode; In the speed control mode, the target drive axle is determined to perform dynamic or static shifting based on the output shaft speed, and the corresponding target speed is determined accordingly. The drive motor of the target drive axle is controlled to adjust its speed according to the target speed, and it is determined whether the drive motor of the target drive axle meets the corresponding shift synchronization conditions. If the conditions are met, the shift hub corresponding to the target drive axle is shifted from neutral to the target gear.

2. The method as described in claim 1, characterized in that, If the electric commercial vehicle is detected to be in an emergency braking condition, the target drive axle to be controlled is determined, specifically including: If the electric commercial vehicle is detected to be in an emergency braking condition, check whether there is a signal indicating that the middle axle has completed the gear shift action. If not, the middle bridge is determined to be the target drive bridge; If so, confirm that the rear axle is the target drive axle.

3. The method as described in claim 1, characterized in that, The process of reducing the target drive axle torque and placing the corresponding shift hub in neutral, in reference to the vehicle speed control of the electric commercial vehicle, specifically includes: Monitor the actual speed of the electric commercial vehicle; If the actual vehicle speed decreases to the set vehicle speed calibration value, the torque of the target drive axle is reduced. If the torque of the target drive axle decreases to a set torque value, the shift hub corresponding to the target drive axle is placed in neutral.

4. The method as described in claim 1, characterized in that, The step of determining whether the target drive axle performs dynamic or static shifting based on the output shaft speed specifically includes: If the absolute value of the output shaft speed is below the set speed and not 0, then the target drive axle performs the above dynamic shifting. If the output shaft speed is 0, the target drive axle performs the static shift.

5. The method as described in claim 4, characterized in that, If the target drive axle performs the dynamic gear shift, determining the corresponding target speed specifically includes: according to n target.1 = n base.1 +Δ n 1× k 1. Determine the target rotational speed; in, n target.1 This indicates the target speed corresponding to the dynamic gear shift; n base.1 This indicates the base speed corresponding to the dynamic shifting. n base.1 = n output × i target , n output This indicates the output shaft speed. i target Indicates the gear ratio of the target gear; Δ n 1 represents the motor speed compensation coefficient corresponding to the dynamic shifting, which is obtained by referring to the brake pedal travel and slope signal from a table; k 1 represents the motor direction coefficient corresponding to the dynamic shift, which is obtained by referring to the direction of the output shaft speed. If the direction of the output shaft speed is positive, k 1=1, if the direction of the output shaft rotation speed is negative. k 1 = -1; If the target drive axle performs the static gear shift, determining the corresponding target speed specifically includes: according to n target.2 = n base.2 × k 2. Determine the target speed corresponding to the static gear shift; in, n target.2 This indicates the target speed corresponding to the static gear shift; n base.2 The base speed corresponding to the static gear shift is obtained by referring to the motor temperature; k 2 represents the motor direction coefficient corresponding to the static shift, which is determined by the motor direction coefficient of the previous cycle.

6. The method as described in claim 1, characterized in that, Before the method controls the drive motor of the target drive axle to adjust its speed according to the target rotational speed, the method further includes: The torque limit is adjusted according to the target speed; wherein the torque limit for dynamic shifting is greater than the torque limit for static shifting.

7. The method as described in claim 1, characterized in that, The shift synchronization condition is specifically the shift synchronization condition corresponding to dynamic shifting, or the shift synchronization condition corresponding to static shifting; The shifting synchronization condition corresponding to the dynamic shifting is: the difference between the actual speed of the drive motor of the target drive axle and the target speed is within a preset speed difference range, and the rate of change of the speed difference between the two is less than or equal to a first rate of change, and is delayed by a first preset delay time; wherein, the preset speed difference range is set with reference to the target gear transmission ratio and the speed difference of the engaging gear. The shift synchronization condition corresponding to the static shift is as follows: the difference between the actual speed of the drive motor of the target drive axle and the target speed is lower than the set speed difference, and the rate of change of the speed difference is less than or equal to the second rate of change, and there is a second set delay time; the set speed difference is lower than the minimum value of the preset speed difference range, and the second rate of change is less than the first rate of change.

8. A shift control system for an electric commercial vehicle, characterized in that, The system includes: The first control module is used to determine the target drive axle to be controlled if the electric commercial vehicle is detected to be in an emergency braking condition, reduce the torque of the target drive axle with reference to the vehicle speed of the electric commercial vehicle, and put the corresponding shift hub in neutral; wherein, the target drive axle is either of the two drive axles of the electric commercial vehicle; the shift hub of the target drive axle being put in neutral indicates that the drive motor of the target drive axle has switched from torque control mode to speed control mode; The judgment module is used to determine whether the target drive axle is performing dynamic shifting or static shifting based on the output shaft speed in the speed control mode, and to determine the corresponding target speed. The second control module is used to control the drive motor of the target drive axle to adjust its speed according to the target speed, and to determine whether the drive motor of the target drive axle meets the corresponding shift synchronization conditions. The switching module is used to, if the conditions are met, switch the shift hub corresponding to the target drive axle from neutral to the target gear.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method according to any one of claims 1-7.

10. An electric commercial vehicle, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method according to any one of claims 1-7.

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