A pure electric two-speed power transmission system shift control method, system and vehicle

Abstract

The present invention relates to the technical field of vehicle transmission systems, and specifically to a pure electric two-speed power transmission system shift control method, system and vehicle. The present invention increases a transition process in the speed regulation stage to ensure that the motor torque can maintain the target speed after the motor speed regulation, thereby improving the stability of the shift control and making the whole vehicle shift more smoothly; when the difference between the real-time motor speed and the target motor speed in the speed regulation stage is within a preset range, the present invention sets the speed regulation torque to 0Nm in advance, which can effectively avoid the drive motor speed from fluctuating around the target speed, prevent the vehicle from shaking due to the speed regulation torque fluctuation, and thus greatly improve driving comfort.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle transmission systems, and in particular to a shift control method, system and vehicle for a pure electric two-speed power transmission system. Background Art

[0002] In recent years, the power system of pure electric vehicles for passenger cars is usually based on a single motor with a single-pole reducer. Its advantages are simple structure, relatively simple control, and low technical risk; its disadvantages are also obvious. Models with low-power motors cannot meet the power requirements well, while models with high-power motors cause power waste and the motors run in a non-efficient range for a long time. Therefore, pure electric vehicles with multi-speed transmissions have gradually appeared on the market. Multi-speed transmissions can not only meet the requirements of low-speed climbing, but also ensure the economy of high-speed driving, and are favored by OEMs.

[0003] The existing single-motor two-speed gearbox shifting scheme has low torque control efficiency and large fluctuations in the process from speed regulation completion to gear shifting by the actuator, which can easily lead to fluctuations in the speed difference between the motor speed and the engaging gear, and then cause gear knocking when engaging the gear, resulting in a decrease in the NVH performance of the entire vehicle. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in view of the deficiencies in the prior art, a pure electric two-speed power transmission system shift control method is provided, which can improve the stability of the pure electric two-speed power transmission system shift control, make the vehicle shift smoother, and improve driving comfort.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A shift control method for a pure electric two-speed power transmission system includes the following control strategies:

[0007] S1, the vehicle controller sends the target gear position to the vehicle transmission control unit in real time;

[0008] S2, when the gearbox control unit determines that the target gear position is inconsistent with the current gear position of the vehicle, the drive motor torque reduction stage control is entered;

[0009] S3, when the torque of the driving motor drops to the target torque, the transmission system synchronizer shifting stage control is entered;

[0010] S4, when the gear-shifting stage is over, the drive motor speed regulation stage is entered;

[0011] S5, when the difference between the real-time speed of the driving motor and the target speed in the speed regulation stage is less than the preset speed difference, entering the speed regulation transition stage control of the driving motor;

[0012] S6, when the shift hub is in gear, the drive motor responds to the wheel end torque demand sent by the vehicle controller in real time and transmits the drive torque to the wheel end.

[0013] Preferably, the transmission system comprises a drive motor, an input shaft, a synchronizer assembly, a first-gear driving gear, a first-gear driven gear, a second-gear driving gear, a second-gear driven gear, an output shaft and a differential;

[0014] The synchronizer assembly is arranged on the input shaft, and the first gear driving gear and the second gear driving gear are respectively fixedly connected with the first gear combining teeth and the second gear combining teeth, the first gear driving gear is meshed with the first gear driven gear, and the second gear driving gear is meshed with the second gear driven gear.

[0015] Preferably, the torque reduction stage control specifically includes:

[0016] The driving motor operates in a torque mode, and the real-time torque of the driving motor is reduced to a target torque T1 at a preset torque reduction rate X;

[0017] The preset torque reduction rate X is adjusted in real time according to the measured shift shock degree, and the target torque T1 is adapted to the damping torque generated by the speed of the driving motor at the current gear.

[0018] Preferably, the control of the gear-shifting stage specifically includes: the drive motor operates in a torque mode, the synchronizer shift motor generates a shift force, and the synchronizer gear sleeve moves axially to a neutral position, so that the drive motor speed is decoupled from the vehicle wheel speed.

[0019] Preferably, the speed regulation stage control specifically includes:

[0020] The driving motor adjusts the real-time speed to a target speed Wa that matches the target gear position;

[0021] The driven end speed Wc of the synchronizer satisfies the following formula:

[0022] Wc=V / 0.377 / r*i 换挡后

[0023] Where V is the current vehicle speed, r is the wheel rolling radius, i 换挡后 is the total speed ratio of the target gear after shifting.

[0024] Preferably, the preset speed difference n2 is a maximum speed difference allowed for gear shifting determined according to the synchronizer sliding film capacity.

[0025] Preferably, the speed regulation transition stage control specifically includes:

[0026] Determine the maintenance torque T2 of the drive motor after reaching the target speed according to the rotational inertia of the transmission system;

[0027] When |n em When -Wa|<n3, the speed regulating torque of the drive motor is set to 0Nm, where n em is the real-time speed of the drive motor, Wa is the target speed of the drive motor in the speed regulation stage, and n3 is the maximum speed difference that meets the comfort requirement calibrated according to the vehicle vibration.

[0028] Compared with the prior art, the present invention has the following main advantages:

[0029] 1. The present invention proposes a shift control method for a pure electric two-speed power transmission system, which increases a transition process in the speed regulation stage to ensure that the motor torque can maintain the target speed after the motor speed regulation, thereby improving the stability of the shift control and making the vehicle shift more smoothly.

[0030] 2. When the difference between the real-time motor speed and the target motor speed in the speed regulation stage is within a preset range, the present invention sets the speed regulation torque to 0 Nm in advance, which can effectively avoid the driving motor speed from fluctuating around the target speed and prevent vehicle shaking caused by speed regulation torque fluctuations, thereby greatly improving driving comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of a single-motor two-speed power transmission system in an embodiment of the present invention;

[0032] Figure 2 It is a logic block diagram of a shift control method for a single-motor two-speed power transmission system in an embodiment of the present invention;

[0033] Figure 3 It is an overall flow chart of the shift control method of a single-motor two-speed power transmission system in an embodiment of the present invention.

[0034] In the figure: 1-first gear driving gear; 2-first gear driven gear; 3-first gear engaging gear; 4-synchronizer gear sleeve; 5-synchronizer gear hub; 6-second gear driving gear; 7-second gear driven gear; 8-second gear engaging gear. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0037] Embodiment 1. This embodiment provides a shift control method for a pure electric two-speed power transmission system. By adding a transition process in the speed regulation stage, it is ensured that the motor torque can maintain the target speed after the motor speed regulation, thereby solving the problem of gear knocking when engaging the gear due to the fluctuation of the speed difference between the motor speed and the engaging teeth, resulting in a decrease in the NVH performance of the entire vehicle.

[0038] like Figure 1 As shown, the pure electric two-speed power transmission system of this embodiment includes a motor EM, an input shaft, a synchronizer assembly (a gear sleeve 4, a gear hub 5, a synchronizer ring, and combining gears 3 and 8), a first-speed driving gear 1, a first-speed driven gear 2, a second-speed driving gear 6, a second-speed driven gear 7, an output shaft and a differential.

[0039] The synchronizer assembly is arranged on the input shaft. The first gear combination teeth and the second gear combination teeth are welded on the first gear driving gear and the second gear driving gear respectively. The first gear master and driven gear are always meshed, and the second gear master and driven gear are always meshed.

[0040] like Figure 2 As shown, the unified shift control method of this embodiment specifically includes the following steps:

[0041] (1) The vehicle controller VECE sends the target gear position. For example, if the current gear position is D1, the vehicle controller VECU changes the target gear position to D2.

[0042] (2) When the transmission control unit TCU detects that the target gear position has changed to D2, which is inconsistent with the current gear position, it enters the torque reduction stage. In the torque reduction stage, the drive motor EM works in the torque mode and reduces at a certain rate X, with T1 as the target torque. Among them, the torque reduction rate X affects the gear shift shock and needs to be adjusted according to the driving experience; the target torque T1 depends on the high-speed damping torque generated by the motor speed in the current gear;

[0043] (3) When the drive motor torque reaches the target torque T1, the gear shifting process begins, and the drive motor EM operates in the torque mode. The synchronizer shift motor generates a shifting force to move the synchronizer gear sleeve axially and return to the neutral position. When the gear sleeve reaches the neutral position, the motor speed and wheel speed are decoupled, and there is no speed ratio relationship.

[0044] (4) Entering the speed regulation stage, since the gear sleeve is in the neutral position, that is, the motor speed and wheel speed are decoupled, the adjustment of the motor speed will not affect the vehicle speed. The speed Wc of the driven end (coupling gear) of the synchronizer is based on the current vehicle speed V (kph), rolling radius r (m) and the total speed ratio i of the gear after the gear shift. 换挡后 The calculation results are:

[0045] Wc=V / 0.377 / r*i 换挡后

[0046] The speed of the active end (gear sleeve) of the synchronizer is the motor speed n em , the drive motor EM works in the speed mode, Wa is the target speed of the drive motor in the speed regulation stage, when |n em When -Wa|<n2 (n2 is the maximum speed difference allowed for gear shifting determined by the synchronizer sliding film capacity), the speed regulation transition stage is entered.

[0047] (5) In the speed regulation transition stage, in order to overcome the damping torque under high-speed rotation of the motor, when the drive motor reaches the target speed, it is necessary to continue to use T2 torque to keep the motor speed from fluctuating. The rotational inertia of the T2 torque transmission system is determined. (Otherwise, when the shift hub drives the gear sleeve to enter the engagement gear, the motor speed will drop, deviating from the target speed and causing the gear to hit.) At this time, the shift motor generates a shift force, causing the synchronizer gear sleeve to move axially and finally connect with the second gear engagement gear fixedly connected to the second gear driving gear. The drive motor torque is transmitted to the output shaft through the gear hub, gear sleeve, engagement gear, driving gear, and driven gear, and finally transmitted to the wheel end.

[0048] Furthermore, in this process, because the actual speed of the drive motor will fluctuate around the target speed, the speed regulating torque will fluctuate between positive and negative values. Due to the existence of gear clearance, when the motor torque changes between positive and negative values, gear knocking will occur and the vehicle will shake. In order to compensate for gear knocking and vehicle shaking, when |n em - When Wa|<n3 (n3 can be calibrated according to the vehicle vibration), the speed control torque is set to 0Nm.

[0049] (6) After the shift hub is in gear, the drive motor responds normally to the wheel end torque demand of the VECU and transmits power to the wheel end.

[0050] Embodiment 2: This embodiment provides a pure electric two-speed power transmission system shift control method, such as Figure 3 As shown, the control strategies mainly include the following:

[0051] S1, the vehicle controller sends the target gear position to the vehicle transmission control unit in real time;

[0052] S2, when the gearbox control unit determines that the target gear position is inconsistent with the current gear position of the vehicle, the drive motor torque reduction stage control is entered;

[0053] S3, when the torque of the driving motor drops to the target torque, the transmission system synchronizer shifting stage control is entered;

[0054] S4, when the gear-shifting stage is over, the drive motor speed regulation stage is entered;

[0055] S5, when the difference between the real-time speed of the driving motor and the target speed in the speed regulation stage is less than the preset speed difference, entering the speed regulation transition stage control of the driving motor;

[0056] S6, when the shift hub is in gear, the drive motor responds to the wheel end torque demand sent by the vehicle controller in real time and transmits the drive torque to the wheel end.

[0057] Furthermore, the torque reduction stage control specifically includes:

[0058] The driving motor operates in a torque mode, and the real-time torque of the driving motor is reduced to a target torque T1 at a preset torque reduction rate X;

[0059] The preset torque reduction rate X is adjusted in real time according to the measured shift shock degree, and the target torque T1 is adapted to the damping torque generated by the speed of the driving motor at the current gear.

[0060] Furthermore, the control of the gear shifting stage specifically includes: the drive motor operates in the torque mode, the synchronizer shifting motor generates the shifting force, and the synchronizer gear sleeve is axially moved to the neutral position, so that the drive motor speed is decoupled from the vehicle wheel speed.

[0061] Furthermore, the speed regulation stage control specifically includes:

[0062] The driving motor adjusts the real-time speed to a target speed Wa that matches the target gear position;

[0063] The driven end speed Wc of the synchronizer satisfies the following formula:

[0064] Wc=V / 0.377 / r*i 换挡后

[0065] Where V is the current vehicle speed, r is the wheel rolling radius, i 换挡后 is the total speed ratio of the target gear after shifting.

[0066] Furthermore, the preset speed difference n2 is a maximum speed difference allowed for gear shifting determined according to the synchronizer sliding film capacity.

[0067] Furthermore, the speed regulation transition stage control specifically includes:

[0068] Determine the maintenance torque T2 of the drive motor after reaching the target speed according to the rotational inertia of the transmission system;

[0069] When |n em When -Wa|<n3, the speed regulating torque of the drive motor is set to 0Nm, where n em is the real-time speed of the drive motor, Wa is the target speed of the drive motor in the speed regulation stage, and n3 is the maximum speed difference that meets the comfort requirement calibrated according to the vehicle vibration.

[0070] Embodiment 3: Based on the same inventive concept, this embodiment also provides a vehicle-mounted control system, including a memory, a processor, and a program stored in the memory and executable on the processor, wherein the processor implements the shift control method as described above when executing the program.

[0071] Embodiment 4: Based on the same inventive concept, this embodiment also provides a manual-automatic vehicle, which is provided with the vehicle-mounted control system as described above.

[0072] Furthermore, all parts involved in this application that are not described in detail are the same as the prior art or are implemented using the prior art.

[0073] In summary:

[0074] 1. The present invention proposes a shift control method for a pure electric two-speed power transmission system, which increases a transition process in the speed regulation stage to ensure that the motor torque can maintain the target speed after the motor speed regulation, thereby improving the stability of the shift control and making the vehicle shift more smoothly.

[0075] 2. When the difference between the real-time motor speed and the target motor speed in the speed regulation stage is within a preset range, the present invention sets the speed regulation torque to 0 Nm in advance, which can effectively avoid the driving motor speed from fluctuating around the target speed and prevent vehicle shaking caused by speed regulation torque fluctuations, thereby greatly improving driving comfort.

[0076] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A shift control method for a pure electric two-speed power transmission system, characterized in that: The control strategies include: The vehicle controller sends the target gear position to the vehicle transmission control unit in real time; When the gearbox control unit determines that the target gear position is inconsistent with the current gear position of the vehicle, the drive motor enters the torque reduction stage control; When the torque of the driving motor drops to the target torque, the transmission system synchronizer shifting stage control is entered; When the gear-shifting stage is over, the drive motor speed regulation stage is entered; The speed regulation stage control specifically includes: The driving motor adjusts the real-time speed to a target speed Wa that matches the target gear position; The driven end speed Wc of the synchronizer satisfies the following formula: Wc=V / 0.377 / r*i 换挡后 Where V is the current vehicle speed, r is the wheel rolling radius, i 换挡后 is the total speed ratio of the target gear after shifting; When the difference between the real-time speed of the driving motor and the target speed in the speed regulation stage is less than the preset speed difference, the driving motor enters the speed regulation transition stage control; The preset speed difference n2 is the maximum speed difference allowed for gear shifting determined according to the synchronizer sliding film capacity; The speed regulation transition stage control specifically includes: Determine the maintenance torque T2 of the drive motor after reaching the target speed according to the rotational inertia of the transmission system. When the drive motor reaches the target speed, continue to use the torque T2 to keep the motor speed from fluctuating. At this time, the shift motor generates a shift force to move the synchronizer sleeve axially and finally connect with the second gear combination tooth fixedly connected to the second gear driving gear. When |n em When -Wa|<n3, the speed regulating torque of the drive motor is set to 0Nm in advance to avoid the drive motor speed fluctuating around the target speed, where n em is the real-time speed of the drive motor, Wa is the target speed of the drive motor in the speed regulation stage, and n3 is the maximum speed difference that meets the comfort requirement calibrated according to the vehicle vibration; When the shift hub is in gear, the drive motor responds to the wheel-end torque demand sent by the vehicle controller in real time and transmits the drive torque to the wheel end.

2. A pure electric two-speed power transmission system shift control method according to claim 1, characterized in that: The transmission system includes a drive motor, an input shaft, a synchronizer assembly, a first-gear driving gear, a first-gear driven gear, a second-gear driving gear, a second-gear driven gear, an output shaft and a differential; The synchronizer assembly is arranged on the input shaft, and the first gear driving gear and the second gear driving gear are respectively fixedly connected with the first gear combining teeth and the second gear combining teeth, the first gear driving gear is meshed with the first gear driven gear, and the second gear driving gear is meshed with the second gear driven gear.

3. A pure electric two-speed power transmission system shift control method according to claim 1, characterized in that: The torque reduction stage control specifically includes: The driving motor operates in a torque mode, and the real-time torque of the driving motor is reduced to a target torque T1 at a preset torque reduction rate X; The preset torque reduction rate X is adjusted in real time according to the measured shift shock degree, and the target torque T1 is adapted to the damping torque generated by the speed of the driving motor at the current gear.

4. A pure electric two-speed power transmission system shift control method according to claim 1, characterized in that: The control of the gear-shifting stage specifically includes: the drive motor operates in a torque mode, the synchronizer shift motor generates a shift force, and the synchronizer gear sleeve is axially moved to a neutral position, so that the drive motor speed is decoupled from the vehicle wheel speed.

5. A vehicle control system, comprising a memory, a processor and a program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the shift control method according to any one of claims 1 to 4 is implemented.

6. A non-transitory readable storage medium having a program stored thereon, characterized in that: When the program is executed by the vehicle control system, the shift control method according to any one of claims 1 to 4 is implemented.

7. A manual-automatic vehicle, characterized in that: Includes the vehicle-mounted control system as described in claim 5.

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