阅读说明：本技术 一种改善电动汽车低速蠕行的方法 (Method for improving low-speed crawling of electric automobile ) 是由 邱爽 尹来承 于泽浩 于 2021-09-08 设计创作，主要内容包括：本发明创造属于汽车行驶控制系统,主要涉及一种改善电动汽车低速驾驶控制的方法。当驾驶员启动车辆,选择到前进挡或倒挡,当驾驶员需要较低车速时,驾驶员踩且只踩下制动后,整车控制器根据接收到的车速、挡位、启动状态、加速踏板、制动力信息,进行逻辑上的判断,如符合预设条件,则会对驱动力进行衰减控制,使车辆以较低速度继续行驶。该方案实施后,可以使车辆减小制动盘磨损,同时降低驱动电机堵转扭矩,减小电机发热,还有降低能量消耗的目的。(The invention belongs to an automobile running control system, and mainly relates to a method for improving low-speed driving control of an electric automobile. When a driver starts the vehicle and selects a forward gear or a reverse gear, when the driver needs a low vehicle speed and steps on the vehicle and only steps on the brake, the vehicle controller performs logical judgment according to the received vehicle speed, gear, starting state, accelerator pedal and braking force information, and if the vehicle meets the preset conditions, the vehicle controller performs attenuation control on the driving force to enable the vehicle to continuously run at the low speed. After the scheme is implemented, the abrasion of a brake disc of a vehicle can be reduced, the locked-rotor torque of a driving motor is reduced, the heating of the motor is reduced, and the purpose of reducing energy consumption is achieved.)

1. A method for improving low-speed crawling of an electric automobile is characterized by comprising the following steps: please refer to fig. 1-2. Fig. 1 shows a schematic diagram of a system 100 related to a method for improving low-speed creep of an electric vehicle. FIG. 2 illustrates control logic for a method of improving creep at low speeds in an electric vehicle.

2. Referring to fig. 1, the method and system 100 for improving low-speed creep of an electric vehicle includes a vehicle starting state and gear monitoring unit 110, a vehicle speed monitoring unit 120, a braking force monitoring unit 130, a driving motor unit 150, and a vehicle controller 140.

3. The starting state and gear monitoring unit 110 is connected with the vehicle control unit 140 and used for monitoring the starting state and gear of the vehicle, the vehicle speed monitoring unit 120 is connected with the vehicle control unit 140 and used for monitoring the vehicle speed of the whole vehicle, the braking force monitoring unit 130 is connected with the vehicle control unit 140 and used for monitoring the braking force of a driver, and the driving motor unit 150 is connected with the vehicle control unit 140 and used for executing a torque instruction of the vehicle control unit.

4. Specifically, S1, the start state and gear monitoring unit 110 sends the current vehicle start state to the vehicle controller 140, where the current vehicle start state is used to determine whether the vehicle is in the start state, and if the vehicle is in the start state, the next step S2 is performed, and if the vehicle is not started, the step S1 is repeated.

And 5, S2, acquiring the current gear information, executing the next step S3 if the current gear information is in a forward gear or a reverse gear, and repeating the step S2 until the gear is in the forward gear or the reverse gear if the current gear information is in the parking gear or the neutral gear. It should be noted that if the vehicle is kept at a certain vehicle speed in the neutral state, the condition of S2 is not satisfied, and the process of S3 cannot be continued.

And 6, S3, when the steps are met, acquiring the current vehicle speed for judging whether the crawling state is achieved, wherein the crawling vehicle speed can be 5-7km/h, and preferably, the vehicle speed judgment threshold is 6 km/h. It should be noted that when the four-wheel vehicle speed is inconsistent, the vehicle speed monitoring unit 120 is required to perform arbitration and give a reasonable vehicle speed, and if the vehicle speed cannot be estimated due to the current special working condition, the vehicle speed monitoring unit 120 should give an invalid instruction.

7, S4, when the above conditions are all satisfied, the vehicle control unit 140 needs to calculate the braking force value of the braking force monitoring unit 130, and after the brake pedal is stepped on, the vehicle control unit no longer responds to the accelerator pedal request, so there is no accelerator pedal determination process in this flow.

And 8, S5, and after the vehicle controller 140 collects information according to the steps, attenuating the output driving force according to the current vehicle starting state, the vehicle gear, the vehicle speed and the braking force, and attenuating the driving force after the vehicle condition meets the vehicle starting state, the gear is the driving state, the vehicle speed is within 6km/h, and the brake pedal is stepped on. The damping value is determined according to the vehicle speed and the braking force, and preferably, the damping force is smaller as the vehicle speed is higher under the same braking force. The greater the braking force, the greater the damping force at the same vehicle speed.

9, S6, after arbitrating other torques of the whole vehicle, the vehicle controller 140 sends out a final driving force, wherein the final driving force is related to the real-time value of the available torque of the motor by the battery power, and the command is sent out after arbitrating the available torque of the motor.

10, S7, after receiving the torque command of vehicle control unit 140, driving motor unit 150 determines whether there is a fault, processes the fault after there is a fault, and if there is no fault, executes the attenuated torque command of vehicle control unit 140.

Technical Field

The invention belongs to an automobile running control system, and mainly relates to a method for improving low-speed driving control of an electric automobile.

Background

With the development of the new energy automobile industry, the number of electric automobiles is increasing day by day, and in order to adapt to the operation habit of the traditional power automobile, part of the electric automobiles still keep the crawling function that the electric automobiles can run at low speed without stepping on an accelerator. The power of a traditional internal combustion engine is limited by the lowest stable rotating speed of an engine, the creeping force needs to be controlled by other devices at low speed, and the creeping force can be controlled by using a motor without assembling the engine.

In the creep control method of the new energy automobile, a certain driving force is output at a low speed to maintain a low speed, the speed is about 6km/h, but when a driver needs a speed of 2-3km/h or even lower, the speed can be reduced only through the braking force, at the moment, a driving motor still works, the energy of the driving motor is converted into the friction heat of a brake disc to be dissipated, and energy waste and brake disc abrasion are caused. Therefore, it is of great practical significance to research a control method for reducing driving force according to braking force, reducing energy loss, improving working conditions of a driving motor and prolonging the service life of a brake disc.

Disclosure of Invention

The invention aims to solve the problems in the prior art and researches and designs a method for reasonably attenuating driving force according to the braking force of a driver during crawling, wherein the method comprises a vehicle starting state and gear monitoring unit, a vehicle speed monitoring unit, a braking force monitoring unit, a driving motor unit and a vehicle control unit. The vehicle speed monitoring unit is connected with the vehicle control unit and used for monitoring the vehicle starting state and the gear position, the vehicle speed monitoring unit is connected with the vehicle control unit and used for monitoring the vehicle speed of the whole vehicle, the braking force monitoring unit is connected with the vehicle control unit and used for monitoring the braking force of a driver, the driving motor unit is connected with the vehicle control unit and used for executing a torque instruction of the vehicle control unit, and the vehicle control unit collects information provided by each unit and comprehensively judges and calculates the driving force of the whole vehicle.

Further, the vehicle starting state and gear monitoring unit can monitor that the vehicle is in a high-voltage state, an ignition state or an off state, and can monitor that the whole vehicle is in a forward gear, a reverse gear or a neutral gear or a parking gear. And sending the state and the gear to the vehicle control unit.

Furthermore, the vehicle speed monitoring unit can calculate the vehicle speed and the vehicle speed effectiveness of the whole vehicle according to different wheel speeds of the current vehicle, and sends the vehicle speed and the vehicle speed effectiveness to the whole vehicle controller.

Furthermore, the braking force monitoring unit can monitor the depth of a brake pedal treaded by a driver, calculate the braking force of the whole vehicle according to the depth of the brake pedal and send the braking force of the whole vehicle to the whole vehicle controller.

Further, the driving motor receives a torque instruction of the whole vehicle controller, the driving motor responds to the torque instruction of the whole vehicle controller according to the self capacity, and the torque instruction is used for driving the whole vehicle to run.

The purpose of the invention is realized as follows: when a driver starts the vehicle and selects a forward gear or a reverse gear, when the driver needs a low vehicle speed and steps on the vehicle and only steps on the brake, the vehicle controller performs logical judgment according to the received vehicle speed, gear, starting state, accelerator pedal and braking force information, and if the vehicle meets the preset conditions, the vehicle controller performs attenuation control on the driving force to enable the vehicle to continuously run at the low speed.

After the scheme is implemented, the abrasion of a brake disc of a vehicle can be reduced, the locked-rotor torque of a driving motor is reduced, the heating of the motor is reduced, and the purpose of reducing energy consumption is achieved.

Drawings

FIG. 1 is a schematic diagram illustrating control units of a method for improving low-speed creep of an electric vehicle according to the invention; in the figure: 110. a vehicle starting state and gear monitoring unit; 120. a vehicle speed monitoring unit; 130 a braking force monitoring unit; 140 a vehicle control unit; 150 drive the motor unit.

FIG. 2 is a control flow chart of a method for improving low-speed creep of an electric vehicle according to the invention;

Detailed Description

The embodiments of the invention will be described in detail below with reference to the accompanying drawings: the present embodiment provides a method for improving low-speed creep of an electric vehicle, please refer to fig. 1 to 2. Fig. 1 shows a schematic diagram of a system 100 related to a method for improving low-speed creep of an electric vehicle. FIG. 2 illustrates control logic for a method of improving creep at low speeds in an electric vehicle.

Referring to fig. 1, the method and system 100 for improving low-speed creep of an electric vehicle includes a vehicle starting state and gear monitoring unit 110, a vehicle speed monitoring unit 120, a braking force monitoring unit 130, a driving motor unit 150, and a vehicle controller 140.

The starting state and gear monitoring unit 110 is connected with the vehicle control unit 140 and used for monitoring the starting state and gear of the vehicle, the vehicle speed monitoring unit 120 is connected with the vehicle control unit 140 and used for monitoring the vehicle speed of the whole vehicle, the braking force monitoring unit 130 is connected with the vehicle control unit 140 and used for monitoring the braking force of a driver, and the driving motor unit 150 is connected with the vehicle control unit 140 and used for executing a torque instruction of the vehicle control unit.

Specifically, S1, the start state and gear monitoring unit 110 sends the current vehicle start state to the vehicle controller 140, where the current vehicle start state is used to determine whether the vehicle is in the start state, and if the vehicle is in the start state, the next step S2 is performed, and if the vehicle is not started, the step S1 is repeated.

And S2, acquiring the current gear information, executing the next step S3 if the current gear information is in a forward gear or a reverse gear, and repeating the step S2 until the gear is in the forward gear or the reverse gear if the current gear information is in the parking gear or the neutral gear. It should be noted that if the vehicle is kept at a certain vehicle speed in the neutral state, the condition of S2 is not satisfied, and the process of S3 cannot be continued.

S3, when the steps are met, acquiring the current vehicle speed for judging whether the crawling state is achieved, wherein the crawling vehicle speed can be 5-7km/h, and preferably, the vehicle speed judgment threshold is 6 km/h. It should be noted that when the four-wheel vehicle speed is inconsistent, the vehicle speed monitoring unit 120 is required to perform arbitration and give a reasonable vehicle speed, and if the vehicle speed cannot be estimated due to the current special working condition, the vehicle speed monitoring unit 120 should give an invalid instruction.

And S4, when the above conditions are all satisfied, the vehicle control unit 140 needs to calculate the braking force value of the braking force monitoring unit 130, and after the brake pedal is stepped on, the vehicle control unit does not respond to the request of the accelerator pedal any more, so that the process of judging the accelerator pedal is not available.

S5, vehicle control unit 140 according to the steps according to the information acquisition, according to the current vehicle starting state, vehicle gear, speed and brake force, output driving force is attenuated, when the vehicle conditions meet vehicle starting, gear is driving state, speed is within 6km/h, and brake pedal is pressed down, the driving force is attenuated. The damping value is determined according to the vehicle speed and the braking force, and preferably, the damping force is smaller as the vehicle speed is higher under the same braking force. The greater the braking force, the greater the damping force at the same vehicle speed.

And S6, after arbitrating other torques of the whole vehicle, the vehicle control unit 140 sends out a final driving force, wherein the final driving force is related to the real-time value of the available torque of the motor by the battery power, and the command is sent out after arbitrating the available torque of the motor.

S7, after receiving the torque command of vehicle controller 140, driving motor unit 150 determines whether there is a fault, and processes the fault after the fault exists, and if there is no fault, executes the attenuated torque command of vehicle controller 140.

In summary, the invention has the following effects:

according to the method for improving the low-speed crawling of the electric automobile, after the torque of the motor is reduced, the torque of the locked-rotor part of the motor is effectively reduced, the use condition of the motor is improved, and the reliability and the durability of the motor are improved.

According to the method for improving the low-speed crawling of the electric automobile, after the torque of the crawling motor is reduced, the noise generated by low-speed friction of the friction plate is effectively reduced, and the noise level of the whole automobile is improved.

The method for improving the low-speed crawling of the electric automobile reduces the abrasion of the brake disc and the friction block in a unit distance of a moving vehicle during crawling, and has a certain effect of prolonging the service life of the brake friction block.