Vehicle torque control method and apparatus, and hybrid vehicle

Abstract

Disclosed in the present application are a vehicle torque control method and apparatus, and a hybrid vehicle. The method is applied to a hybrid vehicle. The method comprises: acquiring a vehicle speed, a rotational speed of a first driving electric motor, a rotational speed of a second driving electric motor, a tire radius, a circumferential coefficient and a vehicle traveling condition; on the basis of the rotational speed of the first driving electric motor, the rotational speed of the second driving electric motor, the tire radius, the vehicle speed and the circumferential coefficient, determining a slip rate corresponding to the vehicle traveling condition; on the basis of the rotational speed of the first driving electric motor, the rotational speed of the second driving electric motor, the tire radius and the circumferential coefficient, determining a front and rear axle wheel speed difference corresponding to the vehicle traveling condition; and if the slip rate corresponding to the vehicle traveling condition meets a preset slip rate condition or the front and rear axle wheel speed difference corresponding to the vehicle traveling condition meets a preset wheel speed difference condition, controlling the driving electric motors to perform torque compensation according to a preset compensation torque limiting condition. The probability of wheels slipping relative to the ground is reduced, thereby improving the stability of a vehicle.

Description

Vehicle torque control method, device and hybrid vehicle

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on July 21, 2023, with application number 202310903902.5 and invention name “A method and device for controlling vehicle torque and a hybrid vehicle”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of vehicle technology, and in particular to a method and device for controlling vehicle torque and a hybrid vehicle. Background Art

[0003] At present, hybrid vehicles experience power interruption on the front or rear axle during gear shifting. To avoid power interruption on a single axle, the existing technology uses the drive motor of one axle to dynamically compensate for torque when the other axle shifts gears. However, due to the short gear shifting time, when the drive motor compensates for the torque, the wheels corresponding to the compensation axle may slip, resulting in certain safety risks for the vehicle.

[0004] Summary of the Invention

[0005] One of the objectives of the embodiments of the present application is to provide a method and device for controlling vehicle torque and a hybrid vehicle.

[0006] The technical solution adopted in the embodiment of this application is:

[0007] In a first aspect, an embodiment of the present application provides a vehicle torque control method, which is applied to a hybrid vehicle. The hybrid vehicle includes an engine, a clutch, a gearbox, a front axle, a rear axle, a first drive motor, a second drive motor, and a power battery. The power battery is connected to a first end of the first drive motor and a first end of the second drive motor. The second end of the first drive motor is connected to a first end of the gearbox and the clutch. The second end of the gearbox is connected to the front axle, and the second end of the second drive motor is connected to the rear axle. Each of the drive motors is powered by the power battery to provide driving power. The control method includes:

[0008] Obtaining vehicle speed, first drive motor speed, second drive motor speed, tire radius, circumferential coefficient, and vehicle driving conditions;

[0009] determining a slip ratio corresponding to the vehicle driving condition based on the first drive motor speed, the second drive motor speed, the tire radius, the vehicle speed, and the circumferential coefficient;

[0010] Determining a front and rear axle wheel speed difference corresponding to the vehicle driving condition based on the first drive motor speed, the second drive motor speed, the tire radius, the circumferential coefficient, and the transmission ratio;

[0011] If the slip ratio corresponding to the vehicle driving condition meets a preset slip ratio condition or the front and rear axle wheel speed difference corresponding to the vehicle driving condition meets a preset wheel speed difference condition, the drive motor is controlled to perform torque compensation according to a preset compensation torque limit condition.

[0012] In a second aspect, an embodiment of the present application provides a vehicle torque control device, which is applied to a hybrid vehicle. The hybrid vehicle includes an engine, a clutch, a gearbox, a front axle, a rear axle, a first drive motor, a second drive motor, and a power battery. The power battery is connected to a first end of the first drive motor and a first end of the second drive motor. The second end of the first drive motor is connected to a first end of the gearbox and the clutch. The second end of the gearbox is connected to the front axle, and the second end of the second drive motor is connected to the rear axle. Each of the drive motors is powered by the power battery to provide driving power, including:

[0013] An acquisition module is used to acquire vehicle speed, first drive motor speed, second drive motor speed, tire radius, circumferential coefficient and vehicle driving conditions;

[0014] a first determining module, configured to determine a slip ratio corresponding to the vehicle driving condition based on a speed of the first drive motor, a speed of the second drive motor, a tire radius, a vehicle speed, and a circular coefficient;

[0015] a second determining module, configured to determine a front and rear axle wheel speed difference corresponding to the vehicle driving condition based on the first drive motor speed, the second drive motor speed, the tire radius, the circumferential coefficient, and the gear ratio;

[0016] The control module is configured to control the drive motor to perform torque compensation according to a preset compensation torque limit condition if the slip ratio corresponding to the vehicle driving condition satisfies a preset slip ratio condition or the front and rear axle wheel speed difference corresponding to the vehicle driving condition satisfies a preset wheel speed difference condition.

[0017] In a third aspect, an embodiment of the present application provides a hybrid vehicle, comprising an engine, a clutch, a gearbox, a front axle, a rear axle, a first drive motor, a second drive motor, and a power battery, wherein the power battery is connected to the first end of the first drive motor and the first end of the second drive motor, the second end of the first drive motor is connected to the first end of the gearbox and the clutch, the second end of the gearbox is connected to the front axle, and the second end of the second drive motor is connected to the rear axle, each of the drive motors is powered by the power battery to provide driving power, and the hybrid vehicle is used to execute any of the methods described in the first aspect.

[0018] The beneficial effect of the vehicle torque control method provided in the embodiment of the present application is that, compared with the prior art in which the wheels corresponding to the compensation electric bridge slip when the driving motor compensates for the torque, when the hybrid vehicle performs dynamic torque compensation, when the slip rate meets the preset slip rate condition or the difference in wheel speed between the front and rear axles meets the preset wheel speed difference condition, torque compensation needs to be performed according to the preset compensation torque limit condition, which further reduces the probability of the wheels slipping relative to the ground, thereby improving the stability of the vehicle, and improving the safety of the vehicle while taking into account comfort.

[0019] The beneficial effect of the vehicle torque control device provided in the embodiment of the present application is that when the vehicle torque control device performs dynamic torque compensation for a hybrid vehicle, when the slip rate meets the preset slip rate condition or the difference in wheel speed between the front and rear axles meets the preset wheel speed difference condition, torque compensation can be performed according to the preset compensation torque limit condition, thereby further reducing the probability of the wheels slipping relative to the ground, thereby improving the stability of the vehicle, and improving the safety of the vehicle while taking into account comfort.

[0020] The beneficial effect of the hybrid vehicle provided by the embodiment of the present application is that when the hybrid vehicle performs dynamic torque compensation, when the slip rate meets the preset slip rate condition or the difference in wheel speed between the front and rear axles meets the preset wheel speed difference condition, torque compensation can be performed according to the preset compensation torque limit condition, thereby further reducing the probability of the wheels slipping relative to the ground, thereby improving the stability of the vehicle, and improving the safety of the vehicle while taking into account comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0022] FIG1 is a schematic structural diagram of a four-wheel drive hybrid vehicle provided by an embodiment of the present application;

[0023] FIG2 is a flow chart of a method for controlling vehicle torque according to an embodiment of the present application;

[0024] 3 is a flow chart illustrating a method of determining a slip ratio corresponding to a vehicle driving condition based on a first drive motor speed, a second drive motor speed, a tire radius, a vehicle speed, and a circular coefficient in step S200 according to another embodiment of the present application;

[0025] FIG4 is a flow chart of determining the front and rear axle wheel speed difference corresponding to the vehicle driving condition based on the first drive motor speed, the second drive motor speed, the tire radius, the circumferential coefficient, and the transmission ratio in step S300 according to another embodiment of the present application;

[0026] 5 is a flowchart illustrating controlling the drive motor to perform torque compensation according to a preset compensation torque limit condition if the slip ratio corresponding to the vehicle driving condition satisfies a preset slip ratio condition in step S400 according to another embodiment of the present application;

[0027] FIG6 is a flowchart illustrating, in step S400 according to another embodiment of the present application, controlling the drive motor to perform torque compensation according to a preset compensation torque limit condition if the front and rear axle wheel speed difference corresponding to the vehicle driving condition satisfies a preset wheel speed difference condition;

[0028] FIG7 is a schematic structural diagram of a vehicle torque control device provided in an embodiment of the present application.

[0029] The figures are marked as follows: 1. engine; 2. clutch; 3. gearbox; 4. front axle; 5. rear axle; 6. first drive motor; 7. second drive motor; 8. power battery; 9. left front wheel; 10. right front wheel; 11. left rear wheel; 12. right rear wheel. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to 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 this application.

[0031] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly specifying the number of technical features. "Multiple" means two or more, unless otherwise expressly specified.

[0032] In the existing technology, when a four-wheel drive vehicle starts on a slippery road or a slope, the vehicle will distribute torque to the rear axle to assist in stable starting; two-wheel drive can be used during normal driving to reduce energy consumption; when the vehicle detects wheel slippage, it will smoothly switch to four-wheel drive mode; and when decelerating, it will also switch to two-wheel drive mode to reduce energy consumption.

[0033] At present, when the front or rear axle of a hybrid vehicle adopts an automated mechanical transmission (AMT) structure, there is a power interruption during gear shifting. In order to avoid the power interruption of a single bridge, the existing technology uses the drive motor of one bridge to dynamically compensate for the torque when the other bridge shifts. However, due to the short gear shifting time, when the drive motor compensates for the torque, there is a possibility that the wheels corresponding to the compensation bridge may slip, resulting in certain safety risks for the vehicle.

[0034] In conventional hybrid vehicles, when one electric axle shifts gears and the other electric axle performs dynamic torque compensation, the wheels corresponding to the compensation axle may slip, resulting in certain safety risks for the vehicle.

[0035] The embodiment of the present application is applied to a hybrid vehicle. As shown in FIG1 , the hybrid vehicle includes an engine 1, a clutch 2, a gearbox 3, a front axle 4, a rear axle 5, a first drive motor 6, a second drive motor 7, and a power battery 8. The power battery 8 is connected to the first end of the first drive motor 6 and the first end of the second drive motor 6. The second end of the first drive motor 6 is connected to the first end of the gearbox 3 and the clutch 2. The second end of the gearbox 3 is connected to the front axle 4. The second end of the second drive motor 7 is connected to the rear axle 5. Each drive motor is powered by the power battery 8 to provide driving power. The first drive motor 6 is the drive motor corresponding to the front axle of the hybrid vehicle, and the second drive motor 7 is the drive motor corresponding to the rear axle of the hybrid vehicle. Among them, the drive motor includes a maximum torque motor (TM motor, Torque Max Motor) and a fourth position motor (P4M motor, Position 4 Motor), that is, the first drive motor includes a maximum torque motor and the second drive motor includes a fourth position motor. Hybrid vehicles also include an engine management system (EMS), a hybrid system vehicle controller (HCU), an electronic stability program (ESP), a motor controller (MCU), a battery management system (BMS), a transmission controller (TCU), etc. The controllers communicate with each other through a controller area network (CAN network).

[0036] The embodiments of the present application obtain vehicle speed, first drive motor speed, second drive motor speed, tire radius, wheel speed, circumferential coefficient, and vehicle driving condition; determine the slip rate corresponding to the vehicle driving condition based on the first drive motor speed, second drive motor speed, tire radius, vehicle speed, and circumferential coefficient; determine the front and rear axle wheel speed difference corresponding to the vehicle driving condition based on the first drive motor speed, second drive motor speed, tire radius, circumferential coefficient, and transmission ratio; if the slip rate corresponding to the vehicle driving condition satisfies a preset slip rate condition or the front and rear axle wheel speed difference corresponding to the vehicle driving condition satisfies a preset wheel speed difference condition, control the drive motor to perform torque compensation according to a preset compensation torque limit condition; because when a hybrid vehicle performs dynamic torque compensation, torque compensation needs to be performed according to the preset compensation torque limit condition when the slip rate satisfies the preset slip rate condition or the front and rear axle wheel speed difference satisfies the preset wheel speed difference condition, compared with the prior art, the probability of wheel slipping relative to the ground is further reduced, thereby improving vehicle stability, while taking into account comfort and improving vehicle safety.

[0037] In order to illustrate the technical solution provided by this application, a detailed description is given below with reference to specific drawings and embodiments.

[0038] In a first aspect, as shown in FIG2 , this embodiment provides a method for controlling vehicle torque, which is applied to a hybrid vehicle. The control method includes steps S100 , S200 , S300 , and S400 .

[0039] Step S100 , obtaining the vehicle speed, the first drive motor speed, the second drive motor speed, the tire radius, the circumferential coefficient and the vehicle driving condition.

[0040] In one embodiment, the vehicle speed, the first drive motor speed, and the second drive motor speed are obtained according to the vehicle's sensors, and the tire radius is obtained based on the vehicle configuration. The circumferential coefficient is a constant, which facilitates the subsequent acquisition of the slip rate and the front and rear axle wheel speed difference.

[0041] In one embodiment, the first drive motor is a drive motor corresponding to the front axle of the hybrid vehicle, for example, a maximum torque drive motor (Torque Max motor, TM), and the second drive motor is a drive motor corresponding to the rear axle of the hybrid vehicle, for example, a Position 4 motor (P4M).

[0042] In one embodiment, a vehicle driving condition includes a first vehicle driving condition and a second vehicle driving condition, wherein the first vehicle driving condition represents a condition in which the rear axle drive of the hybrid vehicle is in gear shifting and the front axle drive is in a compensating torque output condition, and the second vehicle driving condition represents a condition in which the front axle drive of the hybrid vehicle is in gear shifting and the rear axle drive is in a compensating torque output condition. The first vehicle driving condition includes a first vehicle acceleration driving condition and a first vehicle deceleration driving condition, and the second vehicle driving condition includes a second vehicle acceleration driving condition and a second vehicle deceleration driving condition. The first vehicle acceleration driving condition represents a condition in which the rear axle drive is in gear shifting and the front axle drive is in a compensating torque output condition when the hybrid vehicle is accelerating, the first vehicle deceleration driving condition represents a condition in which the rear axle drive is in gear shifting and the front axle drive is in a compensating torque output condition when the hybrid vehicle is decelerating, the second vehicle acceleration driving condition represents a condition in which the front axle drive is in gear shifting and the rear axle drive is in a compensating torque output condition when the hybrid vehicle is accelerating, and the second vehicle deceleration driving condition represents a condition in which the front axle drive is in gear shifting and the rear axle drive is in a compensating torque output condition when the hybrid vehicle is decelerating.

[0043] In step S200 , a slip ratio corresponding to a vehicle driving condition is determined based on a first drive motor speed, a second drive motor speed, a tire radius, a vehicle speed, and a circular coefficient.

[0044] In one embodiment, the slip ratio corresponding to the vehicle driving condition is determined based on the first drive motor speed, the second drive motor speed, the tire radius, the vehicle speed and the circumferential coefficient, so as to facilitate controlling the compensation torque according to the slip ratio corresponding to the vehicle driving condition.

[0045] In one embodiment, the slip ratio includes a first slip ratio corresponding to a first vehicle driving condition and a second slip ratio corresponding to a second vehicle driving condition.

[0046] In one embodiment, as shown in FIG3 , step 200 of determining the slip ratio corresponding to the vehicle driving condition based on the first drive motor speed, the second drive motor speed, the tire radius, the vehicle speed, and the circular coefficient includes steps S210 and S220 .

[0047] In step S210 , a first slip ratio corresponding to a first vehicle driving condition is determined based on a first drive motor speed, a tire radius, a vehicle speed, and a circular coefficient.

[0048] In one embodiment, based on the first drive motor speed, tire radius, vehicle speed and circumferential coefficient, a first slip ratio corresponding to the first vehicle driving condition is determined by a first slip ratio calculation formula, which is conducive to adjusting the output torque of the front axle according to the first slip ratio corresponding to the first vehicle driving condition.

[0049] In one embodiment, the first slip ratio calculation formula is:

[0050] Among them, S f is the first slip ratio;

[0051] n1 is the speed of the first drive motor, in r / min;

[0052] PI is the circular coefficient, and its value is 3.14159;

[0053] r e is the tire radius;

[0054] V is the vehicle speed in km / h.

[0055] Step S220 : determining a second slip ratio corresponding to a second vehicle driving condition based on the second drive motor speed, tire radius, vehicle speed, and circular coefficient.

[0056] In one embodiment, based on the second drive motor speed, tire radius, vehicle speed and circumferential coefficient, a second slip ratio corresponding to the second vehicle driving condition is determined by a second slip ratio calculation formula, which is conducive to adjusting the output torque of the front axle according to the second slip ratio corresponding to the second vehicle driving condition.

[0057] In one embodiment, the second slip ratio calculation formula is:

[0058] Among them, S r is the second slip ratio;

[0059] n2 is the speed of the second drive motor, in r / min;

[0060] PI is the circular coefficient, and its value is 3.14159;

[0061] r e is the tire radius;

[0062] V is the vehicle speed in km / h.

[0063] It should be noted that the vehicle speed in this embodiment is a reference speed. That is, when the vehicle is accelerating, the average of the two slowest wheel speeds among the vehicle's four wheels (i.e., left front wheel 9, right front wheel 10, left rear wheel 11, and right rear wheel 12) is used as the vehicle speed. When the vehicle is decelerating, the average of the two fastest wheel speeds among the four wheels is used as the vehicle speed. Low-pass filtering is also performed on the vehicle speed to prevent excessive speed fluctuations, reduce slip rate fluctuations, avoid the discomfort caused by frequent intervention in the compensation torque, and enhance the driving experience.

[0064] Step S300: determining the front and rear axle wheel speed difference corresponding to the vehicle driving condition based on the first drive motor speed, the second drive motor speed, the tire radius, the circumferential coefficient, and the transmission ratio.

[0065] In one embodiment, based on the first drive motor speed, the second drive motor speed, the tire radius, the circumferential coefficient and the transmission ratio, the front and rear axle wheel speed difference corresponding to the vehicle driving condition is determined, so as to facilitate the control of the compensation torque according to the front and rear axle wheel speed difference corresponding to the vehicle driving condition.

[0066] In one embodiment, the wheel speeds include front left wheel speed, front right wheel speed, rear left wheel speed, and rear right wheel speed, and the transmission ratios include front left wheel transmission ratio, front right wheel transmission ratio, rear left wheel transmission ratio, and rear right wheel transmission ratio.

[0067] In one embodiment, as shown in FIG4 , step S300 determines the front and rear axle wheel speed difference corresponding to the vehicle driving condition based on the first drive motor speed, the second drive motor speed, the tire radius, the circumferential coefficient and the transmission ratio, including steps S310 , S320 , S330 , S340 and S350 .

[0068] Step S310: determining the front axle left wheel speed and the front axle right wheel speed corresponding to the vehicle driving condition based on the first drive motor speed, the tire radius, the circumferential coefficient, the front axle left wheel drive ratio and the front axle right wheel drive ratio.

[0069] Step S320: determining the average wheel speed of the front axle based on the left wheel speed and the right wheel speed of the front axle.

[0070] Step S330: determining the rear axle left wheel speed and the rear axle right wheel speed corresponding to the vehicle driving condition based on the second drive motor speed, tire radius, circumferential coefficient, rear axle left wheel drive ratio and rear axle right wheel drive ratio.

[0071] Step S340: determining the average wheel speed of the rear axle based on the speed of the left wheel of the rear axle and the speed of the right wheel of the rear axle.

[0072] Step S350: determining the front and rear axle wheel speed difference based on the front axle wheel speed and the rear axle wheel speed.

[0073] It should be noted that low-pass filtering is performed on both the front and rear axle wheel speeds of the vehicle to avoid excessive fluctuations in vehicle speed, reduce fluctuations in slip rate, avoid discomfort caused by frequent intervention in the compensation torque, and improve the vehicle experience.

[0074] In step S400 , if the slip ratio corresponding to the vehicle driving condition satisfies a preset slip ratio condition or the front and rear axle wheel speed difference corresponding to the vehicle driving condition satisfies a preset wheel speed difference condition, the drive motor is controlled to perform torque compensation according to a preset compensation torque limit condition.

[0075] In one embodiment, if the slip rate corresponding to the vehicle driving condition meets the preset slip rate condition or the front and rear axle wheel speed difference corresponding to the vehicle driving condition meets the preset wheel speed difference condition, the drive motor is controlled to perform torque compensation according to the preset compensation torque limit condition. When the slip rate meets the preset slip rate condition or the front and rear axle wheel speed difference meets the preset wheel speed difference condition, torque compensation can be performed according to the preset compensation torque limit condition, thereby reducing the probability of the wheels slipping relative to the ground, thereby improving the stability of the vehicle, and improving the safety of the vehicle while taking into account comfort.

[0076] In one embodiment, if the slip ratio corresponding to the vehicle driving condition satisfies a preset slip ratio condition or the front and rear axle wheel speed difference corresponding to the vehicle driving condition satisfies a preset wheel speed difference condition, controlling the drive motor to perform torque compensation according to a preset compensation torque limit condition includes:

[0077] If the slip ratio corresponding to the vehicle's driving condition meets the preset slip ratio condition, the drive motor is controlled to perform torque compensation according to the preset compensation torque limit condition; or, if the front and rear axle wheel speed difference corresponding to the vehicle's driving condition meets the preset wheel speed difference condition, the drive motor is controlled to perform torque compensation according to the preset compensation torque limit condition.

[0078] In one embodiment, the preset slip ratio condition includes a first preset slip ratio condition and a second preset slip ratio condition.

[0079] In one embodiment, the first preset slip rate condition is that the absolute value of the first slip rate is greater than or equal to a preset slip rate threshold; the second preset slip rate condition is that the absolute value of the second slip rate is greater than or equal to the preset slip rate threshold, wherein the preset slip rate thresholds include the first preset slip rate threshold and the second preset slip rate threshold.

[0080] In one embodiment, 3%≦S1<15%, S1 is a first preset slip rate threshold, 15%≦S2<30%, S2 is a second preset slip rate threshold.

[0081] In one embodiment, the preset compensation torque limit condition includes a first preset compensation torque limit condition and a second preset compensation torque limit condition.

[0082] In one embodiment, as shown in FIG5 , in step S400 , if the slip ratio corresponding to the vehicle driving condition satisfies a preset slip ratio condition, controlling the drive motor to perform torque compensation according to a preset compensation torque limit condition includes:

[0083] In step S410 , if the first slip ratio corresponding to the first vehicle driving condition satisfies a first preset slip ratio condition, the first drive motor is controlled to perform torque compensation according to a preset compensation torque limit condition.

[0084] In one embodiment, if a first slip ratio corresponding to a first vehicle driving condition satisfies a first preset slip ratio condition, controlling the first drive motor to perform torque compensation according to a preset compensation torque limit condition includes:

[0085] If the absolute value of the first slip ratio corresponding to the first vehicle driving condition is greater than or equal to the preset slip ratio threshold, the first drive motor is controlled to perform torque compensation according to the first preset compensation torque limit condition, wherein the first preset compensation torque limit condition is that the gradient of the compensation torque is corrected based on the correction coefficient corresponding to the first slip ratio, and the correction coefficient is less than 1; after weakening the gradient of the compensation torque by using the correction coefficient corresponding to the first slip ratio, the gradient of the compensation torque is reduced within the gear shifting time, that is, the slope of the compensation torque within the gear shifting time becomes smoother, thereby ensuring a smooth transition of the vehicle's acceleration and speed, reducing the probability of the wheels slipping relative to the ground, and at the same time improving the stability of the vehicle and also improving the safety of the vehicle.

[0086] In one embodiment, a correction coefficient is determined based on a slip ratio lookup table. The larger the slip ratio, the smaller the correction coefficient. For example, in a first vehicle acceleration condition and a first vehicle deceleration condition, the absolute value of the first slip ratio is 10%, and the correction coefficient corresponding to the 10% slip ratio is 0.9. Consequently, the current compensation torque gradient is weakened to 90%, and the slope of the compensation torque decreases. If the absolute value of the first slip ratio is greater than or equal to 15%, the correction coefficient is smaller, the current compensation torque gradient is weakened to a greater extent, and the slope of the compensation torque decreases further, resulting in a more gradual slope.

[0087] If the absolute value of the first slip ratio corresponding to the first vehicle operating condition is greater than or equal to a preset slip ratio threshold, the first drive motor is controlled to perform torque compensation according to a second preset compensation torque limit condition, wherein the second preset compensation torque limit condition is that the compensation torque corresponding to the first slip ratio and the drive torque output by the drive motor are determined to be larger or smaller based on the vehicle operating condition. After the compensation torque corresponding to the first slip ratio and the drive torque output by the drive motor are determined to be larger or smaller based on the vehicle operating condition, the magnitude of the compensation torque is reduced during the shift time, that is, the compensation torque is controlled to a maximum or minimum torque during the shift time to prevent the compensation torque from exceeding the drive torque output by the drive motor. It should be noted that the drive torque output by the drive motor is a limited drive torque to avoid safety risks caused by excessive drive torque.

[0088] In one embodiment, if the absolute value of the first slip ratio corresponding to the first vehicle acceleration driving condition is greater than or equal to a preset slip ratio threshold, the first drive motor is controlled to have a compensation torque corresponding to the first slip ratio and a driving torque output by the drive motor take a larger value based on the vehicle driving condition; if the absolute value of the first slip ratio corresponding to the first vehicle deceleration driving condition is greater than or equal to the preset slip ratio threshold, the first drive motor is controlled to have a compensation torque corresponding to the first slip ratio and a driving torque output by the drive motor take a smaller value based on the vehicle driving condition.

[0089] In step S411 , if the second slip ratio corresponding to the second vehicle driving condition satisfies a second preset slip ratio condition, the second drive motor is controlled to perform torque compensation according to a preset compensation torque limit condition.

[0090] In one embodiment, if the second slip ratio corresponding to the second vehicle driving condition satisfies a second preset slip ratio condition, controlling the second drive motor to perform torque compensation according to a preset compensation torque limit condition includes:

[0091] If the absolute value of the second slip rate corresponding to the second vehicle driving condition is greater than or equal to the preset slip rate threshold, the second drive motor is controlled to perform torque compensation according to the first preset compensation torque limit condition, wherein the first preset compensation torque limit condition is that the gradient of the compensation torque is corrected based on the correction coefficient corresponding to the second slip rate, and the correction coefficient is less than 1; after weakening the gradient of the compensation torque by using the correction coefficient corresponding to the second slip rate, the gradient of the compensation torque is reduced within the gear shifting time, that is, the slope of the compensation torque within the gear shifting time becomes smoother, ensuring a smooth transition of the vehicle's acceleration and speed, reducing the probability of the wheels slipping relative to the ground, and at the same time improving the stability of the vehicle and also improving the safety of the vehicle.

[0092] In one embodiment, a correction coefficient is determined based on a slip ratio lookup table. The larger the slip ratio, the smaller the correction coefficient. For example, in the second vehicle acceleration and deceleration operating conditions, the absolute value of the second slip ratio is 10%, and the correction coefficient corresponding to a 10% slip ratio is 0.9. Consequently, the current compensation torque gradient is weakened to 90%, reducing the slope of the compensation torque. If the absolute value of the second slip ratio is greater than or equal to 15%, the correction coefficient is smaller, the current compensation torque gradient is weakened to a greater extent, and the slope of the compensation torque is reduced further, resulting in a more gradual slope.

[0093] If the absolute value of the second slip ratio corresponding to the second vehicle operating condition is greater than or equal to a preset slip ratio threshold, the second drive motor is controlled to perform torque compensation according to a second preset compensation torque limit condition. The second preset compensation torque limit condition is that the compensation torque corresponding to the second slip ratio and the drive torque output by the drive motor are determined to be either greater or lesser based on the vehicle operating condition. By using the compensation torque corresponding to the second slip ratio and the drive torque output by the drive motor to be determined to be either greater or lesser based on the vehicle operating condition, the magnitude of the compensation torque is reduced during the shift time, i.e., the compensation torque is controlled to a maximum or minimum torque during the shift time to prevent the compensation torque from exceeding the drive torque output by the drive motor. It should be noted that the drive torque output by the drive motor is a limited drive torque to prevent safety risks caused by excessive drive torque.

[0094] In one embodiment, if the absolute value of the second slip ratio corresponding to the second vehicle acceleration driving condition is greater than or equal to a preset slip ratio threshold, the second drive motor is controlled to have a compensation torque corresponding to the second slip ratio and a driving torque output by the drive motor, so as to take a larger value based on the vehicle driving condition; if the absolute value of the second slip ratio corresponding to the second vehicle deceleration driving condition is greater than or equal to the preset slip ratio threshold, the second drive motor is controlled to have a compensation torque corresponding to the second slip ratio and a driving torque output by the drive motor, so as to take a smaller value based on the vehicle driving condition.

[0095] In one embodiment, the preset wheel speed difference condition is that the absolute value of the front and rear axle wheel speed difference is greater than or equal to a preset wheel speed difference threshold. The preset wheel speed difference threshold includes a first preset wheel speed difference threshold and a second preset wheel speed difference threshold, and the second preset wheel speed difference threshold is greater than or equal to the first preset wheel speed difference threshold. For example, the preset wheel speed difference threshold may be within the wheel speed range corresponding to a drive motor speed range of 120 rpm to 260 rpm. It should be noted that, in this embodiment, the ranges of the first and second preset wheel speed difference thresholds are not subject to specific numerical restrictions and are set based on the torque compensation corresponding to the vehicle's driving conditions.

[0096] In the prior art, when torque compensation is performed under different vehicle driving conditions, the vehicle may still slip due to the large difference between the front axle wheel speed (referred to as the front axle wheel speed) and the rear axle wheel speed (referred to as the rear axle wheel speed). Therefore, it is necessary to control the drive motor to perform torque compensation according to the preset compensation torque limit conditions.

[0097] In one embodiment, as shown in FIG6 , in step S400 , if the front and rear axle wheel speed difference corresponding to the vehicle driving condition meets the preset wheel speed difference condition, the drive motor is controlled to perform torque compensation according to the preset compensation torque limit condition, including steps S420 and S421 .

[0098] In step S420 , if the front and rear axle wheel speed difference corresponding to the first vehicle driving condition satisfies a preset wheel speed difference condition, the first drive motor is controlled to perform torque compensation according to a preset compensation torque limit condition.

[0099] In one embodiment, if the absolute value of the front and rear axle wheel speed difference corresponding to the first vehicle driving condition is greater than or equal to a preset wheel speed difference threshold, the first drive motor is controlled to perform torque compensation according to a preset compensation torque limit condition.

[0100] In step S421 , if the front and rear axle wheel speed difference corresponding to the second vehicle driving condition meets a preset wheel speed difference condition, the second drive motor is controlled to perform torque compensation according to a preset compensation torque limit condition.

[0101] In one embodiment, if the absolute value of the front and rear axle wheel speed difference corresponding to the second vehicle driving condition is greater than or equal to a preset wheel speed difference threshold, the second drive motor is controlled to perform torque compensation according to a preset compensation torque limit condition.

[0102] It can be understood that when the absolute value of the slip ratio is greater than or equal to a first preset slip ratio threshold, or the front and rear axle wheel speed difference is greater than or equal to the first preset wheel speed difference threshold, the hybrid vehicle's hybrid system vehicle controller (Hybrid Control Unit, HCU) controls the drive motor to perform torque compensation according to the preset compensation torque limit condition; when the absolute value of the slip ratio is greater than or equal to a second preset slip ratio threshold, or the front and rear axle wheel speed difference is greater than or equal to the second preset wheel speed difference threshold, the hybrid vehicle's electronic stability program (ESP) intervenes, and the hybrid vehicle controller (Hybrid Control Unit, HCU) also controls the drive motor to perform torque compensation according to the preset compensation torque limit condition based on the torque limit of the electronic stability system.

[0103] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0104] Compared with the prior art, this embodiment has the following beneficial effects:

[0105] This embodiment is applied to a hybrid vehicle, which includes an engine, a clutch, a gearbox, a front axle, a rear axle, a first drive motor, a second drive motor, and a power battery. The power battery is connected to a first end of the first drive motor and a first end of the second drive motor. The second end of the first drive motor is connected to a first end of the gearbox and the clutch. The second end of the gearbox is connected to the front axle, and the second end of the second drive motor is connected to the rear axle. Each drive motor is powered by the power battery to provide driving power. The vehicle speed, the speed of the first drive motor, the speed of the second drive motor, the tire radius, the circumferential coefficient, and the vehicle driving condition are obtained; and the slip rate corresponding to the vehicle driving condition is determined based on the speed of the first drive motor, the speed of the second drive motor, the tire radius, the vehicle speed, and the circumferential coefficient. Based on the speed of the first drive motor, the speed of the second drive motor, the tire radius and the circumferential coefficient, the front and rear axle wheel speed difference corresponding to the vehicle driving condition is determined; if the slip rate corresponding to the vehicle driving condition meets the preset slip rate condition or the front and rear axle wheel speed difference corresponding to the vehicle driving condition meets the preset wheel speed difference condition, the drive motor is controlled to perform torque compensation according to the preset compensation torque limit condition; because when a hybrid vehicle performs dynamic torque compensation, when the slip rate meets the preset slip rate condition or the front and rear axle wheel speed difference meets the preset wheel speed difference condition, torque compensation needs to be performed according to the preset compensation torque limit condition. Compared with the existing technology, the probability of the wheel slipping relative to the ground is further reduced, thereby improving the stability of the vehicle, while taking into account comfort, it also improves the safety of the vehicle.

[0106] In a second aspect, as shown in FIG7 , this embodiment provides a vehicle torque control device 100 , which is applied to a hybrid vehicle. The hybrid vehicle includes an engine 1 , a clutch 2 , a gearbox 3 , a front axle 4 , a rear axle 5 , a first drive motor 6 , a second drive motor 7 , and a power battery 8 . The power battery 8 is connected to a first end of the first drive motor 6 and a first end of the second drive motor 7 . The second end of the first drive motor 6 is connected to a first end of the gearbox 3 and the clutch 2 . The second end of the gearbox 3 is connected to the front axle 4 , and the second end of the second drive motor 7 is connected to the rear axle 5 . Each drive motor is powered by the power battery 8 to provide driving power, including:

[0107] The acquisition module 110 is used to acquire the vehicle speed, the first drive motor speed, the second drive motor speed, the tire radius, the circumferential coefficient and the vehicle driving condition.

[0108] The first determination module 120 is configured to determine a slip ratio corresponding to a vehicle driving condition based on a first drive motor speed, a second drive motor speed, a tire radius, a vehicle speed, and a circular coefficient.

[0109] The second determination module 130 is configured to determine a front and rear axle wheel speed difference corresponding to the vehicle driving condition based on the first drive motor speed, the second drive motor speed, the tire radius, and the circumferential coefficient.

[0110] The control module 140 is used to control the drive motor to perform torque compensation according to the preset compensation torque limit condition if the slip ratio corresponding to the vehicle driving condition meets the preset slip ratio condition or the front and rear axle wheel speed difference corresponding to the vehicle driving condition meets the preset wheel speed difference condition.

[0111] It should be noted that the information interaction, execution process, etc. between the above-mentioned devices / modules are based on the same concept as the method embodiment of this application. Their specific functions and technical effects can be found in the method embodiment section and will not be repeated here.

[0112] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0113] In the third aspect, an embodiment of the present application provides a hybrid vehicle, including an engine 1, a clutch 2, a gearbox 3, a front axle 4, a rear axle 5, a first drive motor 6, a second drive motor 7 and a power battery 8. The power battery 8 is connected to the first end of the first drive motor 6 and the first end of the second drive motor 7. The second end of the first drive motor 6 is connected to the first end of the gearbox 3 and the clutch 2. The second end of the gearbox 3 is connected to the front axle 4, and the second end of the second drive motor 7 is connected to the rear axle 5. Each drive motor is powered by the power battery 8 to provide driving power. The hybrid vehicle is used to execute any of the methods described in the first aspect.

[0114] In one embodiment, the electronic stability program (ESP) of a hybrid vehicle sets a limited driving torque for the torque output by the front axle drive motor or the torque output by the rear axle drive motor. During normal operation, the hybrid control unit (HCU) of the hybrid vehicle controls the front axle drive motor and the rear axle drive motor to output corresponding torques respectively according to the distribution ratio of the driving torque between the axles. When the hybrid vehicle is in a first vehicle driving condition or a second vehicle driving condition, in order to avoid the situation where the wheels corresponding to the compensation axles slip when the hybrid vehicle shifts gears on one axle and performs dynamic torque compensation on the other axle, when the absolute value of the slip ratio is greater than or equal to a first preset slip ratio threshold, or the difference in wheel speed between the front and rear axles is greater than or equal to the first preset wheel speed difference threshold, the hybrid control unit (HCU) of the hybrid vehicle controls the drive motor to perform torque compensation according to the preset compensation torque limit condition. When the absolute value of the slip ratio is greater than or equal to a second preset When a slip rate threshold is set, or the difference between the front and rear axle wheel speeds is greater than or equal to a second preset wheel speed difference threshold, the hybrid vehicle's electronic stability system (ESP) intervenes, and the hybrid system vehicle controller (HCU) also controls the drive motor to perform torque compensation according to a preset compensation torque limit condition based on the torque limit of the electronic stability system; because when the hybrid vehicle performs dynamic torque compensation, when the slip rate meets the preset slip rate condition or the front and rear axle wheel speed difference meets the preset wheel speed difference condition, torque compensation needs to be performed according to the preset compensation torque limit condition, thereby reducing the probability of the wheel slipping relative to the ground, thereby improving the stability of the vehicle, and taking into account comfort while also improving the safety of the vehicle.

[0115] It can be understood that the beneficial effects of the second to third aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0116] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0117] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0118] In the embodiments provided in this application, it should be understood that the disclosed devices / network equipment and methods can be implemented in other ways. For example, the device / network equipment embodiments described above are merely illustrative. For example, the division of the modules or units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0119] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A method for controlling vehicle torque, characterized in that: Applied to a hybrid vehicle, the hybrid vehicle includes an engine, a clutch, a gearbox, a front axle, a rear axle, a first drive motor, a second drive motor and a power battery, the power battery is connected to a first end of the first drive motor and a first end of the second drive motor, the second end of the first drive motor is connected to a first end of the gearbox and the clutch, the second end of the gearbox is connected to the front axle, the second end of the second drive motor is connected to the rear axle, each drive motor is powered by the power battery to provide driving power, and the control method includes: Obtaining vehicle speed, first drive motor speed, second drive motor speed, tire radius, circular coefficient, transmission ratio and vehicle driving condition; Determining a slip ratio corresponding to the vehicle driving condition based on the first drive motor speed, the second drive motor speed, the tire radius, the vehicle speed, and the circumferential coefficient; Determining a front and rear axle wheel speed difference corresponding to the vehicle driving condition based on the first drive motor speed, the second drive motor speed, the tire radius, the circumferential coefficient and the transmission ratio; If the slip ratio corresponding to the vehicle driving condition satisfies a preset slip ratio condition or the front and rear axle wheel speed difference corresponding to the vehicle driving condition satisfies a preset wheel speed difference condition, the drive motor is controlled to perform torque compensation according to a preset compensation torque limit condition.

2. The method according to claim 1, characterized in that The vehicle driving condition includes a first vehicle driving condition and a second vehicle driving condition, the first vehicle driving condition represents a condition in which the rear axle drive of the hybrid vehicle is in gear shifting and the front axle drive is in a compensation torque output condition, the second vehicle driving condition represents a condition in which the front axle drive of the hybrid vehicle is in gear shifting and the rear axle drive is in a compensation torque output condition, and the slip ratio includes a first slip ratio corresponding to the first vehicle driving condition and a second slip ratio corresponding to the second vehicle driving condition; Determining a slip rate corresponding to the vehicle driving condition based on the first drive motor speed, the second drive motor speed, the tire radius, the vehicle speed, and the circumferential coefficient includes: Based on the first driving motor speed, the tire radius, the vehicle speed and the circumferential coefficient determining a first slip ratio corresponding to the first vehicle driving condition; A second slip ratio corresponding to the second vehicle driving condition is determined based on the second drive motor speed, the tire radius, the vehicle speed, and the circumferential coefficient.

3. The method according to claim 2, characterized in that If the slip ratio corresponding to the vehicle driving condition satisfies a preset slip ratio condition or the front and rear axle wheel speed difference corresponding to the vehicle driving condition satisfies a preset wheel speed difference condition, controlling the drive motor to perform torque compensation according to a preset compensation torque limit condition, including: If the slip ratio corresponding to the vehicle driving condition meets the preset slip ratio condition, the drive motor is controlled to perform torque compensation according to the preset compensation torque limit condition; or, If the wheel speed difference between the front and rear axles corresponding to the vehicle driving condition meets a preset wheel speed difference condition, the drive motor is controlled to perform torque compensation according to a preset compensation torque limit condition.

4. The method according to claim 3, characterized in that The preset slip ratio condition includes a first preset slip ratio condition and a second preset slip ratio condition, the first drive motor is a drive motor corresponding to the front axle of the hybrid vehicle, and the second drive motor is a drive motor corresponding to the rear axle of the hybrid vehicle; If the slip ratio corresponding to the vehicle driving condition meets the preset slip ratio condition, controlling the drive motor to perform torque compensation according to the preset compensation torque limit condition, including: If the first slip ratio corresponding to the first vehicle driving condition satisfies a first preset slip ratio condition, controlling the first drive motor to perform torque compensation according to a preset compensation torque limit condition; If the second slip ratio corresponding to the second vehicle driving condition satisfies a second preset slip ratio condition, the second drive motor is controlled to perform torque compensation according to a preset compensation torque limit condition.

5. The method according to claim 4, characterized in that The first preset slip ratio condition is that an absolute value of the first slip ratio is greater than or equal to a preset slip ratio threshold.

6. The method according to claim 4, characterized in that The second preset slip ratio condition is that the absolute value of the second slip ratio is greater than or equal to a preset slip ratio threshold.

7. The vehicle torque control method according to claim 5 or 6, characterized in that: The preset slip rate threshold comprises a first preset slip rate threshold; Among them, 3%≦S1<15%, and S1 is the first preset slip rate threshold.

8. The vehicle torque control method according to claim 5 or 6, characterized in that: The preset slip rate threshold value further includes a second preset slip rate threshold value; Among them, 15%≦S2<30%, and S2 is the second preset slip rate threshold.

9. The method according to claim 3, characterized in that The first drive motor is a drive motor corresponding to the front axle of the hybrid vehicle, and the second drive motor is a drive motor corresponding to the rear axle of the hybrid vehicle; If the front and rear axle wheel speed difference corresponding to the vehicle driving condition meets the preset wheel speed difference condition, the drive motor is controlled to perform torque compensation according to the preset compensation torque limit condition, including: If the front and rear axle wheel speed difference corresponding to the first vehicle driving condition meets a preset wheel speed difference condition, controlling the first drive motor to perform torque compensation according to a preset compensation torque limit condition; If the front and rear axle wheel speed difference corresponding to the second vehicle driving condition meets the preset wheel speed difference condition, the second drive motor is controlled to perform torque compensation according to the preset compensation torque limit condition.

10. The method according to claim 9, characterized in that The preset wheel speed difference condition is that the absolute value of the wheel speed difference between the front and rear axles is greater than or equal to a preset wheel speed difference threshold.

11. The method according to any one of claims 1 to 10, characterized in that: The preset compensation torque limiting condition includes a first preset compensation torque limiting condition; The first preset compensation torque limiting condition is that the gradient of the compensation torque is corrected based on a correction coefficient corresponding to the slip ratio, and the correction coefficient is less than 1.

12. The method according to any one of claims 1 to 10, characterized in that: The preset compensation torque limiting condition also includes a second preset compensation torque limiting condition; The second preset compensation torque limiting condition is that the compensation torque corresponding to the slip ratio and the driving torque output by the driving motor take a larger value or a smaller value based on the vehicle driving condition.

13. A vehicle torque control device, characterized in that: Applied to a hybrid vehicle, the hybrid vehicle includes an engine, a clutch, a gearbox, a front axle, a rear axle, a first drive motor, a second drive motor and a power battery, the power battery is connected to a first end of the first drive motor and a first end of the second drive motor, the second end of the first drive motor is connected to a first end of the gearbox and the clutch, the second end of the gearbox is connected to the front axle, the second end of the second drive motor is connected to the rear axle, and each of the drive motors is powered by the power battery to provide driving power, including: An acquisition module, used to acquire vehicle speed, first drive motor speed, second drive motor speed, tire radius, circumferential coefficient and vehicle driving condition; A first determination module, configured to determine a slip ratio corresponding to the vehicle driving condition based on the first drive motor speed, the second drive motor speed, the tire radius, the vehicle speed and the circular coefficient; A second determination module is used to determine the front and rear axle wheel speed difference corresponding to the vehicle driving condition based on the first drive motor speed, the second drive motor speed, the tire radius, the circumferential coefficient and the transmission ratio; The control module is used to control the drive motor to perform torque compensation according to a preset compensation torque limit condition if the slip rate corresponding to the vehicle driving condition meets a preset slip rate condition or the front and rear axle wheel speed difference corresponding to the vehicle driving condition meets a preset wheel speed difference condition.

14. A hybrid vehicle, characterized in that: The hybrid vehicle comprises an engine, a clutch, a gearbox, a front axle, a rear axle, a first drive motor, a second drive motor and a power battery, wherein the power battery is connected to a first end of the first drive motor and a first end of the second drive motor, the second end of the first drive motor is connected to a first end of the gearbox and the clutch, the second end of the gearbox is connected to the front axle, the second end of the second drive motor is connected to the rear axle, each of the drive motors is powered by the power battery to provide driving power, and the hybrid vehicle is used to execute the method as claimed in any one of claims 1 to 8.

Images