Gear shifting control method and system and vehicle

Abstract

The invention provides a gear shifting control method and system and a vehicle, the gear shifting control method is used for a vehicle driving system provided with a gear shifting actuator set to be a brushless direct current motor, and the gear shifting control method comprises the following steps that a current target gear is obtained according to gear shifting operation of a user, and a current shifting fork position is obtained; in response to the situation that it is judged that the position of the shifting fork is not changed after the preset gear shifting time, the gear shifting actuator is switched into a non-inductive control mode; whether a rotor of the gear shifting actuator can rotate normally or not is judged; and if not, it is judged that mechanical clamping stagnation happens to the driving system, and gear shifting is not conducted any more, and if yes, it is judged that electric control clamping stagnation happens to the driving system, and the driving system is switched to the target gear from the current actual gear through a gear shifting actuator in the non-inductive control mode.

Description

Technical Field

[0001] This application relates to the field of vehicle drive system technology, and more specifically, to a shift control method, system, and vehicle. Background Technology

[0002] With the development of new energy vehicle technology, vehicle electrification has become a major trend in the automotive industry. Many electric vehicles use electric drive axles to replace traditional drive and transmission systems. Electric drive axles are a type of drive axle that are driven by electric motors and can integrate the motors onto the axle to achieve integration and high efficiency.

[0003] Depending on their structure, electric drive axles currently mainly include integral electric drive axles primarily used in commercial vehicles and integrated electric drive systems primarily used in passenger vehicles. In some known electric drive axles, the shift actuator is generally set as a brushless direct current motor (BLDC), which drives the shift fork of the dog clutch to achieve gear engagement and disengagement.

[0004] Brushless DC motors are typically equipped with three Hall sensors, each corresponding to one of the motor's three phases. As the motor rotor rotates, changes in the magnetic field cause changes in the Hall sensor output signals. These three Hall sensors divide the rotor position into six 60° Hall sectors. By measuring the signals from these three Hall sensors, the current rotor position, especially the current Hall sector, can be calculated to locate the rotor and thus determine the motor speed.

[0005] In known electric drive axles, there are generally two reasons for shifting jamming. One is mechanical jamming caused by structural faults in the gears or other mechanical mechanisms, such as motion interference or transmission chain interruption. The other is electronic control jamming caused by Hall sensor malfunction, preventing the brushless DC motor from operating normally. The common solution for shifting jamming in known electric drive axles is to stop the axle from operating whenever shifting jamming occurs, thus preventing the vehicle from moving normally.

[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0007] Depending on the specific circumstances, one of the objectives of this application is to provide a method for shift control of the drive system in the event of shift jamming.

[0008] In addition, this application aims to solve or alleviate other technical problems existing in the prior art.

[0009] According to one aspect of this application, the following is provided:

[0010] A shift control method for a vehicle drive system having a shift actuator configured as a brushless DC motor, the shift control method comprising the following steps:

[0011] The current target gear and the current shift fork position are obtained based on the user's shifting operation.

[0012] In response to determining that the position of the shift fork has not changed after a preset shift time, the shift actuator is switched to a sensorless control mode.

[0013] Determine whether the rotor of the shift actuator can rotate normally; if not, determine that the drive system is mechanically stuck and stop shifting; if yes, determine that the drive system is electrically stuck and switch the drive system from the current actual gear to the target gear through the shift actuator in the sensorless control mode.

[0014] According to another aspect of this application, this application provides a shift control system, including:

[0015] The data acquisition module obtains the current target gear and the current shift fork position based on the user's shifting operation.

[0016] The shift actuator control system responds to the following: after a preset shift time, if it determines that the shift fork position has not changed, it switches the shift actuator to a contactless control mode; and it determines whether the rotor of the shift actuator can rotate normally. If not, it determines that the drive system has mechanically jammed and stops controlling the shift actuator to shift gears. If yes, it determines that the drive system has electronically jammed and controls the shift actuator to switch the drive system from the current actual gear to the target gear in the contactless control mode.

[0017] The shift actuator is a brushless DC motor. The shift actuator drives the shift fork to move through its rotor to achieve shifting.

[0018] According to another aspect of this application, this application provides a vehicle that includes the shift control system described above.

[0019] The advantages of this application include:

[0020] 1. The shift control method of this application can determine the type of shift jamming in the vehicle drive system to decide whether to continue shifting or stop the drive system, rather than directly stopping the vehicle drive system and causing the vehicle to stop; and when the shift jamming type is detected to be electronically controlled jamming caused by Hall sensor failure, the shifting operation can be continued by switching the shift actuator to a sensorless control mode, without stopping the shifting process of the drive system, thus ensuring that the vehicle continues to drive normally.

[0021] 2. The shift controller configured as a brushless DC motor in this application can perform sensory control during normal shifting and switch to sensorless control when the Hall sensor fails. It adjusts the commutation frequency based on the shift fork speed as a feedback signal, thereby pushing the shift fork to move to the target position to achieve shifting. No additional hardware is required for sensorless control of the brushless DC motor. The structure is simple and the cost is low.

[0022] 3. The shift control method in this application can also diagnose the faulty Hall sensor when electronic control jamming occurs, so as to identify which Hall sensor has failed, so as to facilitate subsequent fault handling operations. Furthermore, the diagnosis can be performed in parallel with the shift operation, thus achieving efficient shift control and fault diagnosis. Attached Figure Description

[0023] Referring to the accompanying drawings, the above and other features of this application will become apparent, wherein,

[0024] Figure 1 A schematic flowchart of a shift control method according to one embodiment of this application is shown;

[0025] Figure 2 A schematic diagram of a shift control system according to one embodiment of this application is shown. Detailed Implementation

[0026] It is readily understood that, based on the technical solution of this application, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of this application. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this application and should not be considered as the entirety of this application or as limitations or restrictions on the technical solution of this application.

[0027] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the structures shown in the accompanying drawings. These are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive. Furthermore, the terms "first," "second," "third," and similar expressions are used for descriptive and distinguishing purposes only and should not be construed as indicating or implying the relative importance of the corresponding components or the order of components or assembly sequence.

[0028] Brushless DC motors typically use Hall effect sensors mounted on the rotor to detect rotor position and determine motor speed. This control method is highly stable and has a fast response speed, and is known as sensored control of brushless DC motors. However, some brushless DC motors can determine their speed indirectly without using Hall effect sensors. This is achieved through methods such as back electromotive force (EMF), inductance, flux linkage, high-frequency pulse methods, and other intelligent techniques. This control method is low-cost and allows for longer wiring lengths; it is known as sensorless control of brushless DC motors.

[0029] In known electric drive bridges that use brushless DC motors as shift actuators, the brushless DC motors typically employ sensor-based control. This means that three Hall effect sensors are usually installed on the brushless DC motor to detect the rotor position, enabling sensor-based control. Therefore, shifting jams in such electric drive bridges fall into two categories: mechanical jams caused by structural failures in the gear shifting gears or other mechanical mechanisms, and electronically controlled jams caused by Hall effect sensor malfunctions that prevent the brushless DC motor from functioning properly. For mechanical jams, since it's a mechanical structure failure, the electric drive bridge is usually stopped directly to detect and repair the shifting jam. However, for electronically controlled jams, only the Hall effect sensors are malfunctioning, preventing the sensor-based control of the brushless DC motor from executing correctly, rather than indicating a problem with the brushless DC motor's mechanical structure. In other words, the brushless DC motor rotor can still rotate normally, and the shifting mechanism in the drive system can still function normally. In this situation, if the brushless DC motor can be directly switched to the sensorless control mode, the brushless DC motor can continue to work normally, thereby realizing the shifting operation of the shift actuator without stopping the vehicle and ensuring its normal operation.

[0030] The first aspect of this application provides a shift control method capable of identifying the current shift jam type and, upon determining that the shift jam type is electronically controlled jam, performing a shift via sensorless control of a brushless DC motor without stopping the operation of the electric drive bridge or stopping the vehicle. Furthermore, this control method can also diagnose which Hall sensor has malfunctioned. (Reference) Figure 1 It shows a schematic flowchart of a shift control method according to one embodiment of this application. Figure 1 S100-S300 in the diagram correspond to each step in this control method. The shift control method of this application is used in a vehicle drive system, particularly an electric drive axle, which has a shift actuator configured as a brushless DC motor. The shift control method includes the following steps:

[0031] S100: Obtain the current target gear and the current shift fork position based on the user's shifting operation;

[0032] S200: In response to the determination that the shift fork position has not changed after a preset shift time, the shift actuator is switched to the sensorless control mode.

[0033] S300: Determine whether the rotor of the shift actuator can rotate normally; if not, determine that the drive system is mechanically stuck and stop shifting; if yes, determine that the drive system is electrically stuck and switch the drive system from the current actual gear to the target gear through the shift actuator in the sensorless control mode.

[0034] In the first step S100 of this method, the user's target gear and the current gear information are first obtained. The user's target gear is obtained, for example, through the user's operation of the gear shift actuator, such as the user's movement of the gear shift lever. The target gear reflects the user's shifting intention and the gear that should correspond to the position of the gear shift lever on the gear shift actuator. The current gear information is determined by the current position of the shift fork. The shift fork is used for clutch shifting, and its actual position determines the current gear of the electric drive axle.

[0035] In the second step S200, it is determined whether shifting jamming has occurred. If the shift fork position does not change after the preset shifting time, it proves that the gear position of the electric drive axle has not changed and remains at the level before the user operated the shift fork actuator, thus indicating that shifting jamming has occurred. The preset shifting time is, for example, the average time from when the user operates the shift actuator to when the vehicle successfully shifts gears. Upon detecting shifting jamming, the shift actuator is directly switched to a contactless control mode instead of immediately stopping its operation, preparing for the next step to check whether the rotor can rotate normally.

[0036] In the third step S300, it is first determined whether the rotor can rotate normally. If the rotor cannot rotate normally, it proves that the rotor, shift fork, shift gear, or other mechanical components are stuck, that is, a mechanical jam has occurred. At this time, it is determined that the drive system has mechanical jamming, the shift actuator no longer works, and no longer performs shifting operations. However, if the rotor can rotate normally, it proves that the rotor is not stuck, and the shift fork and other mechanical components connected to the rotor can also move normally. In this case, it can be determined that the drive system has electronic control jamming, that is, because the Hall sensor has failed, the brushless DC motor cannot detect the rotor position, and therefore cannot control the rotation of the brushless DC motor through sensor control. However, the rotor of the motor itself can rotate. If the brushless DC motor is controlled by an adapted control method at this time, it can also work normally. In this case, since the brushless DC motor in this application has switched to sensorless control mode, the brushless DC motor can continue to work under sensorless control, causing the rotor to rotate to move the shift fork and switch the drive system from the current actual gear to the target gear. Therefore, in the event of electronic control malfunction, the drive system does not need to stop completely and cause the vehicle to stop. Instead, it can continue to shift gears through the sensorless control of the brushless DC motor, without affecting the normal operation of the vehicle.

[0037] In one embodiment of this application, the electronic control jamming is caused by a Hall sensor malfunction in the shift actuator. Electronic control jamming caused by a Hall sensor malfunction differs from mechanical jamming in that it does not affect the normal movement of the brushless DC motor rotor, nor does it affect the movement of the shift fork. Therefore, in the case of this electronic control jamming, as long as the control method can be switched to keep the brushless DC motor running normally, shifting can still be achieved, allowing the vehicle to continue driving.

[0038] In one embodiment of this application, when it is determined that the drive system is experiencing electronic control malfunction, the shift actuator in the contactless control mode moves the shift fork from its current position to the target shift fork position corresponding to the target gear. The shift actuator in the contactless control mode operates similarly to that in the sensory control mode; both achieve gear shifting by moving the shift fork via a rotor. After the user operates the shift actuator, the rotor rotates, moving the shift fork from its current position to the target shift fork position matching the target gear, thus achieving gear shifting. User gear shifting can be divided into two types: disengaging and engaging. Disengaging means the user needs to shift the current gear to neutral; in this case, the shift actuator in the contactless control mode directly adjusts the current shift fork position to the shift fork position corresponding to neutral. Engaging means the user needs to shift the current gear to another target gear, such as upshifting or downshifting; in this case, the shift actuator in the contactless control mode adjusts the current shift fork position to the shift fork position corresponding to the user's target gear.

[0039] In one embodiment of this application, switching the drive system from the current actual gear to the target gear via a shift actuator in a seamless control mode includes the following steps:

[0040] Using a preset first commutation frequency as the input signal, the rotor is driven by the shift actuator at the first commutation frequency;

[0041] The zero-crossing point of the brushless DC motor voltage is collected as a feedback signal;

[0042] The input signal is corrected in real time based on the feedback signal.

[0043] In this embodiment, the sensorless control of the shift actuator is achieved through the "back electromotive force method." Since the rotor generates an induced electromotive force in the stator windings during rotation, and this induced electromotive force is in the opposite direction to the energized voltage of the windings, it is called back electromotive force. During the operation of the brushless motor, within the time period when each two phases of the windings are energized, there is a point where the polarity of the back electromotive force of the unenergized winding changes—that is, the point where the back electromotive force changes from positive to negative or from negative to positive. This point is called the zero-crossing point. Utilizing this characteristic of back electromotive force, as long as the zero-crossing point of the back electromotive force can be accurately detected and delayed by 30°, the moment when commutation is required can be determined, and thus the rotor position can be accurately detected. Therefore, in this embodiment, collecting the zero-crossing point of the brushless DC motor voltage as a feedback signal to correct the commutation frequency of the brushless DC motor enables precise control of the brushless DC motor even without Hall sensor signals.

[0044] In one embodiment of this application, switching the drive system from the current actual gear to the target gear via a shift actuator in a seamless control mode includes the following steps:

[0045] Using a preset first commutation frequency as the input signal, the rotor is driven by the shift actuator at the first commutation frequency;

[0046] The real-time position of the shift fork is collected, and the moving speed of the shift fork is calculated based on the real-time position of the shift fork as a feedback signal.

[0047] The input signal is corrected in real time based on the feedback signal.

[0048] In this embodiment, sensorless control of the brushless DC motor is achieved through closed-loop feedback control, enabling the brushless DC motor to maintain its motion accuracy even without a Hall sensor signal. Traditionally, brushless DC motors using sensorless control typically employ a back-EMF method. However, to achieve sensorless control using this method, additional hardware, such as a microcontroller or back-EMF comparator, is usually required to detect zero-crossing moments and determine the commutation frequency. In this embodiment, however, no additional hardware is needed. Instead, the commutation frequency is corrected using the fork movement speed, calculated from the real-time position of the fork, as a feedback signal. In other words, the brushless DC motor in this embodiment is equipped with a Hall sensor and only requires sensored control when the Hall sensor is functioning correctly, eliminating the need for additional hardware for sensorless control. However, when the Hall sensor malfunctions but gear shifting still needs to continue, the brushless DC motor can use the movement speed of the shift fork as a feedback signal to perform contactless control for a period of time, thus enabling the gear shifting actuator to perform the shift. This not only simplifies the structure of the brushless DC motor and saves costs, but also ensures that the brushless DC motor can switch to contactless control mode in case of electronic control failure, enabling the brushless DC motor to operate normally and ensuring the shifting safety of the drive system.

[0049] In one embodiment of this application, after determining that an electronic control jam has occurred in the drive system, the Hall sensors of the shift actuator are diagnosed to identify the faulty Hall sensor. In this embodiment, when an electronic control jam is detected in the drive system, not only can shifting be performed normally through the sensorless control of the brushless DC motor, but the three Hall sensors can also be diagnosed to identify the faulty Hall sensor, so as to accurately replace the faulty Hall sensor and improve the efficiency of solving the shift jam problem.

[0050] In one embodiment of this application, when it is determined that the position of the shift fork has not changed, the Hall sector where the rotor of the current shift actuator is located is identified;

[0051] Diagnosing the Hall sensor of the gear shift actuator includes the following steps:

[0052] Using the Hall sector as a standard, the rotor is rotated at least one revolution, and the output signal of the Hall sensor is acquired in real time;

[0053] Hall sensors whose output signals do not change are identified as faulty Hall sensors.

[0054] Brushless DC motors typically employ three Hall effect sensors, dividing the rotor position into six 60° Hall sectors. Each Hall sector corresponds to different combinations of digital signals from the three Hall sensors, specifically logic signals consisting only of 0s and 1s. Therefore, by combining the logic signals from the three Hall sensors, the current Hall sector of the rotor can be determined, thus pinpointing the rotor position with a resolution of 60°. Table 1 illustrates the correspondence between the Hall sensor logic signals and Hall sectors. As shown in Table 1, each Hall sector corresponds to a different set of logic signal combinations. For a single Hall sensor, its logic signal must change at least once during one rotor rotation, i.e., as the rotor passes through the six Hall sectors. Therefore, this method can be used to identify the faulty Hall sensor. First, the Hall sector where the rotor is located at the moment of shifting jam is acquired. Then, using that Hall sector as a reference, the rotor is rotated at least one revolution. For example, if the acquired Hall sector is Hall sector 5, the rotor must rotate at least once more through Hall sector 5. This means rotating at least one full rotation. Hall sensors whose logic signals remain unchanged during this process can be identified as faulty. For instance, Hall sensors whose logic signals remain 0 or 1 throughout at least one rotation of the rotor can be identified as faulty. This method allows for easy detection of faulty Hall sensors and can be synchronized with the sensorless gear shifting process via a shift actuator. Specifically, as the rotor continues to rotate for gear shifting, especially during at least one full rotation, the logic signals of the Hall sensors are detected in parallel to identify the faulty sensor. This detection method is fast, accurate, and requires no additional detection time.

[0055]

[0056] Table 1: Correspondence between the logic signals of the Hall sensor and the Hall sectors

[0057] A second aspect of this application discloses a shift control system 10 for a vehicle drive system including a shift actuator configured as a brushless DC motor. This shift control system 10 can detect shift jamming in the drive system and can still achieve normal shifting of the drive system under specific shift jamming conditions, such as electronically controlled jamming. (Reference) Figure 2 This diagram illustrates a module schematic of a shift control system 10 according to one embodiment of the present application. The shift control system 10 includes:

[0058] The data acquisition module 100 obtains the current target gear and the current shift fork position based on the user's shifting operation.

[0059] The shift actuator control system 200, in response to determining that the shift fork position has not changed after a preset shift time, switches the shift actuator 300 to a contactless control mode; and determines whether the rotor of the shift actuator 300 can rotate normally; if not, it determines that the drive system has mechanically jammed and stops controlling the shift actuator 300 to shift gears; if so, it determines that the drive system has electronically jammed and controls the shift actuator 300 to switch the drive system from the current actual gear to the target gear in the contactless control mode.

[0060] The shift actuator 300 is a brushless DC motor. The shift actuator 300 drives the shift fork to move through its rotor to achieve shifting.

[0061] In one embodiment of the second aspect of this application, the brushless DC motor is equipped with a Hall sensor, and under normal operating conditions, the Hall sensor is used for sensor-controlled operation to drive the shift fork.

[0062] In one embodiment of the second aspect of this application, the shift control system 10 further includes:

[0063] The diagnostic subsystem diagnoses the Hall sensors of the shift actuator 300 after the shift actuator control system 200 determines that the drive system has experienced electronic control lag, in order to identify the faulty Hall sensors.

[0064] The shift control system 10 has all the beneficial technical effects of the aforementioned shift control method, which will not be repeated here.

[0065] A third aspect of this application also proposes a vehicle that includes the shift control system described above.

[0066] The vehicle possesses all the beneficial technical effects of the aforementioned shift control system, which will not be elaborated upon here.

[0067] It should be understood that the shift control system of this application can be installed in various vehicles, including passenger cars, trucks, buses, hybrid vehicles, pure electric vehicles, etc. Therefore, the subject matter of this application also aims to protect various vehicles equipped with the shift control system of this application.

[0068] It should be understood that all the above preferred embodiments are exemplary and not restrictive, and various modifications or variations made by those skilled in the art to the specific embodiments described above under the concept of this application should be within the scope of legal protection of this application.

Claims

1. A shift control method characterized by, For a vehicle drive system having a shift actuator configured as a brushless DC motor, the shift control method includes the following steps: The current target gear and the current shift fork position are obtained based on the user's shifting operation. In response to determining that the position of the shift fork has not changed after a preset shift time, the shift actuator is switched to a sensorless control mode. Determine whether the rotor of the gear shifting actuator can rotate normally; If not, it is determined that the drive system has mechanically jammed and will no longer shift gears. If yes, it is determined that the drive system has electronically jammed, and the drive system will be switched from the current actual gear to the target gear by the shift actuator in the sensorless control mode.

2. The shift control method according to claim 1, characterized by, The electronic control jamming is caused by a malfunction of the Hall sensor in the shift actuator.

3. The shift control method according to claim 1, characterized in that, When it is determined that the drive system is experiencing electronic control malfunction, the shift actuator in the sensorless control mode moves the shift fork from its current position to the target shift fork position corresponding to the target gear.

4. The shift control method according to claim 3, characterized in that, Switching the drive system from the current actual gear to the target gear via the shift actuator in the aforementioned seamless control mode includes the following steps: The rotor is driven at the first commutation frequency by the shift actuator using a preset first commutation frequency as the input signal. The real-time position of the shift fork is collected, and the moving speed of the shift fork is calculated based on the real-time position of the shift fork as a feedback signal. The input signal is corrected in real time based on the feedback signal.

5. The shift control method according to claim 3, characterized in that, Switching the drive system from the current actual gear to the target gear via the shift actuator in the aforementioned seamless control mode includes the following steps: The rotor is driven at the first commutation frequency by the shift actuator using a preset first commutation frequency as the input signal. The zero-crossing point of the brushless DC motor voltage is collected as a feedback signal; The input signal is corrected in real time based on the feedback signal.

6. The shift control method according to claim 2, characterized by, After determining that the drive system has experienced electronic control jamming, the Hall sensor of the shift actuator is diagnosed to identify the faulty Hall sensor.

7. The shift control method according to claim 6, characterized in that, When it is determined that the position of the shift fork has not changed, the Hall sector where the rotor of the current shift actuator is located is identified. Diagnosing the Hall sensor of the shift actuator includes the following steps: Using the Hall sector as a standard, the rotor is rotated at least one revolution, and the output signal of the Hall sensor is acquired in real time; Hall sensors whose output signals do not change are identified as faulty Hall sensors.

8. A gear shifting control system, characterized in that, include: The data acquisition module obtains the current target gear and the current shift fork position based on the user's shifting operation. The shift actuator control system responds to the fact that after a preset shift time, if it determines that the position of the shift fork has not changed, it switches the shift actuator to a sensorless control mode; and determines whether the rotor of the shift actuator can rotate normally. If not, it is determined that the drive system has mechanically jammed, and the shift actuator is no longer controlled to shift gears. If yes, it is determined that the drive system has electronically jammed, and the shift actuator is controlled in a contactless control mode to switch the drive system from the current actual gear to the target gear. The shift actuator is a brushless DC motor. The shift actuator drives the shift fork to move through its rotor to achieve shifting.

9. The shift control system according to claim 8, characterized in that, The brushless DC motor is equipped with a Hall sensor, and under normal operating conditions, it is controlled by the Hall sensor to drive the movement of the shift fork.

10. A vehicle, characterized in that, The vehicle includes a shift control system according to claim 8 or 9.

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