阅读说明：本技术 一种制动能量回收的控制方法及控制装置 (Control method and control device for braking energy recovery ) 是由 盘朝奉 李银刚 陈燎 江浩斌 王健 洪健 陶袁雪 于 2019-08-23 设计创作，主要内容包括：本发明公开了一种制动能量回收的控制方法及控制装置,所述控制方法包括：实时采集车辆的行驶状态数据,确定驾驶员的制动意图,根据驾驶员的制动意图,通过对与制动踏板连接的真空助力器的真空度进行修正,根据修正结果进行电机制动力与液压制动力的协调分配,并按照分配结果进行制动能量回收,本发明可以在保证制动效能的基础上提高制动能量回收效率。(The invention discloses a control method and a control device for braking energy recovery, wherein the control method comprises the following steps: the method comprises the steps of collecting driving state data of a vehicle in real time, determining the braking intention of a driver, correcting the vacuum degree of a vacuum booster connected with a brake pedal according to the braking intention of the driver, performing coordinated distribution of motor braking force and hydraulic braking force according to a correction result, and recovering braking energy according to a distribution result.)

1. A control method for braking energy recovery is characterized in that when a vehicle is in a state that an accelerator pedal is released, a vehicle controller calculates a wheel slip rate S, compares the slip rate S with a preset value S, adjusts the vacuum degree to be higher than a normal value when S is larger than or equal to S, calculates a proportionality coefficient K if S is smaller than S, compares K-1 with a threshold value K', and controls the vacuum degree by adopting a logic threshold control method.

2. The control method for braking energy recovery according to claim 1, wherein the vacuum level is collected by a vacuum level sensor installed in a front chamber of the vacuum booster.

3. The control method for recovering braking energy according to claim 2, wherein an air side of the vacuum booster is fixedly connected with the brake pedal, the front cavity of the vacuum booster is connected with an air storage tank through a first electromagnetic valve, and the front cavity of the vacuum booster is further connected with an electronic vacuum pump through a second electromagnetic valve.

4. The control method for braking energy recovery according to claim 3, wherein the first solenoid valve is a one-way normally closed solenoid valve, and the second solenoid valve is a one-way normally open solenoid valve.

5. The control method for braking energy recovery according to claim 3, wherein the vacuum booster is in a first passage to the air tank via a first solenoid valve, and the vacuum booster is in a second passage to the air tank via a second solenoid valve.

6. The control method for braking energy recovery according to claim 3, wherein the vacuum sensor, the electronic vacuum pump, the first solenoid valve and the second solenoid valve are in signal connection with a vehicle control unit.

7. The control method of braking energy recovery of claim 1, wherein the braking energy recovery is performed in a single cycleThe proportional coefficient K is generated by the vehicle controller according to the motor braking force F_mHydraulic braking force F_hAnd target braking force F_rThe calculation result is specifically as follows:

8. the control method for recovering braking energy according to claim 5, wherein the specific process of controlling the vacuum degree by the logic threshold control method is as follows:

(1) if K-1 is larger than K', the two electromagnetic valves are not electrified, the first channel is closed, the second channel is opened, the electronic vacuum pump is started, and the atmosphere in the front cavity of the vacuum booster is pumped into the air storage tank;

(2) if K-1 is less than or equal to K ', judging the size relationship between K-1 and-K':

when K-1< -K', the two electromagnetic valves are electrified, the first channel is opened, the second channel is closed, and the high-pressure gas stored in the gas storage tank is introduced into the front cavity of the vacuum booster;

when-K' is less than or equal to K-1, only the second electromagnetic valve is electrified, and the two channels are closed.

9. The utility model provides a brake energy recuperation's controlling means, its characterized in that, includes vacuum booster, gas holder and electronic vacuum pump, install vacuum sensor in the vacuum booster ante-chamber, vacuum booster ante-chamber is through first solenoid valve and gas tank connection, and vacuum booster ante-chamber still is connected with electronic vacuum pump through the second solenoid valve, vacuum sensor, electronic vacuum pump, first solenoid valve and second solenoid valve all through with vehicle control unit signal connection.

10. The control device for braking energy recovery of claim 9, wherein the first solenoid valve is a one-way normally closed solenoid valve and the second solenoid valve is a one-way normally open solenoid valve.

Technical Field

The invention relates to the technical field of braking energy recovery, in particular to a control method and a control device for braking energy recovery.

Background

The electromechanical composite braking system is a braking system which utilizes the combined action of hydraulic braking and electric motor braking. When the driving motor of the electric automobile runs in a power generation mode, the driving motor is called regenerative braking, mechanical energy of automobile braking is converted into electric energy to be stored in a battery, and the driving range of the electric automobile can be remarkably increased. The driving motor firstly intervenes in braking to provide regenerative braking force, and the hydraulic braking force begins to intervene at the moment because the characteristic of the driving motor enables the regenerative braking force not to meet the total braking force requirement, so the composite braking control unit needs to coordinate and control the proportion of the regenerative braking and the hydraulic braking and change the size of the hydraulic braking force according to the changed regenerative braking force. The existing compound brake control technology research mainly focuses on reducing or delaying the input of pedal force on the basis of not changing the structure of a traditional mechanical brake system so as to realize the maximum output of electric brake force, and partial electric brake force has to be sacrificed to ensure the consistency and comfort of pedal feeling so as to enable hydraulic brake force to intervene earlier.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a braking energy recovery control method and a braking energy recovery control device, which can eliminate or reduce the condition that hydraulic pressure intervenes in composite braking too early and improve the energy recovery efficiency; meanwhile, the hydraulic braking response of the vehicle under the emergency braking working condition is ensured, and the safety of the vehicle is ensured.

The technical purpose is achieved through the following technical scheme.

When a vehicle is in a state that an accelerator pedal is released, a vehicle controller calculates a wheel slip rate S, compares the slip rate S with a preset value S, adjusts the vacuum degree to be higher than a normal value when S is larger than or equal to S, calculates a proportionality coefficient K if S is smaller than S, compares K-1 with a threshold value K', and controls the vacuum degree by adopting a logic threshold control method.

Further, the vacuum degree is acquired by a vacuum degree sensor installed in a front cavity of the vacuum booster.

Further, vacuum booster's air side and brake pedal fixed connection, vacuum booster front chamber pass through first solenoid valve and gas tank connection, and vacuum booster front chamber still passes through the second solenoid valve and is connected with electron vacuum pump.

Furthermore, the first electromagnetic valve is a one-way normally closed electromagnetic valve, and the second electromagnetic valve is a one-way normally open electromagnetic valve.

Further, the vacuum booster is in a first passage to the air storage tank via the first solenoid valve, and the vacuum booster is in a second passage to the air storage tank via the second solenoid valve.

Furthermore, the vacuum degree sensor, the electronic vacuum pump, the first electromagnetic valve and the second electromagnetic valve are in signal connection with the whole vehicle controller.

Further, the proportionality coefficient K is generated by the vehicle control unit according to the electric motor braking force F_mHydraulic braking force F_hAnd target braking force F_rThe calculation result is specifically as follows:

furthermore, the logic threshold control method controls the vacuum degree in a specific process that:

(1) if K-1 is larger than K', the two electromagnetic valves are not electrified, the first channel is closed, the second channel is opened, the electronic vacuum pump is started, and the atmosphere in the front cavity of the vacuum booster is pumped into the air storage tank;

(2) if K-1 is less than or equal to K ', judging the size relationship between K-1 and-K':

when K-1< -K', the two electromagnetic valves are electrified, the first channel is opened, the second channel is closed, and the high-pressure gas stored in the gas storage tank is introduced into the front cavity of the vacuum booster;

when-K' is less than or equal to K-1, only the second electromagnetic valve is electrified, and the two channels are closed.

A control device for braking energy recovery comprises a vacuum booster, an air storage tank and an electronic vacuum pump, wherein a vacuum degree sensor is installed in a front cavity of the vacuum booster, the front cavity of the vacuum booster is connected with the air storage tank through a first electromagnetic valve, the front cavity of the vacuum booster is also connected with the electronic vacuum pump through a second electromagnetic valve, and the vacuum degree sensor, the electronic vacuum pump, the first electromagnetic valve and the second electromagnetic valve are in signal connection with a whole vehicle controller; the first electromagnetic valve is a one-way normally closed electromagnetic valve, and the second electromagnetic valve is a one-way normally open electromagnetic valve.

The invention has the beneficial effects that: according to the braking intention of a driver, the vacuum degree of a vacuum booster connected with a brake pedal is corrected, the motor braking force and the hydraulic braking force are distributed in real time according to the correction result, the condition that hydraulic pressure intervenes in composite braking too early is eliminated or reduced, and the energy recovery efficiency is improved; meanwhile, the hydraulic braking response of the vehicle under the emergency braking working condition is ensured, and the safety of the vehicle is ensured.

Drawings

FIG. 1 is a flow chart of a brake energy recovery control method;

FIG. 2 is a schematic diagram of a gas path principle design of an electronic vacuum pump according to an embodiment of the present invention;

FIG. 3 is a graph illustrating the characteristic of a vacuum booster under different vacuum levels according to an embodiment of the present invention.

Detailed Description

The invention will be further described with reference to the drawings and the detailed description, but the scope of the invention is not limited thereto.

As shown in fig. 2, a schematic diagram of the principle design of an air circuit of an electronic vacuum pump is shown, a vacuum degree adjusting unit connected with a vehicle control unit comprises a vacuum booster, a vacuum degree sensor, an electronic vacuum pump, an electromagnetic valve, an overpressure valve and an air storage tank, wherein the air side of the vacuum booster is fixedly connected with a brake pedal, the vacuum degree sensor is installed in a front cavity of the vacuum booster and used for acquiring a vacuum degree value in the front cavity, the front cavity of the vacuum booster is connected with the air storage tank through a first electromagnetic valve, the vacuum booster is connected with the air storage tank through the first electromagnetic valve to form a first channel, the front cavity of the vacuum booster is also connected with the electronic vacuum pump through a second electromagnetic valve, the vacuum booster is connected with the air storage tank through the second electromagnetic; an overpressure valve is arranged between the electronic vacuum pump and the gas storage tank and used for preventing overload and playing a role in protecting the system. The vacuum degree sensor, the electronic vacuum pump, the first electromagnetic valve and the second electromagnetic valve are connected with the whole vehicle controller through leads.

As shown in fig. 1, a braking energy recovery control method includes the steps of:

step one, the vehicle control unit judges the running state of the vehicle, if the vehicle accelerator pedal is in a released state, the vehicle speed sensor acquires the speed v of the vehicle, the wheel speed sensor acquires the wheel speed omega, and the vehicle control unit acquires the vehicle speed v and the wheel speed omega, so that the wheel slip rate is calculated:

where r is the wheel radius.

Step two, comparing the slip rate S with a preset value S (the preset value S is influenced by various conditions such as road adhesion coefficient, vehicle speed, tire structure and the like, and the value of the preset value is 20% under general conditions)

If S is larger than or equal to a preset value S, the vehicle is in an emergency braking state, the wheel locking and slipping trend is obvious, ABS (Antilock Brake System) intervenes for work, no braking energy recovery is carried out at the moment, the whole vehicle controller starts an electronic vacuum pump, the vacuum degree value in the vacuum booster is corrected to be above a normal value, and the normal value of the vacuum degree value is-66.7 +/-1.3 kpa according to the requirement of automobile industry standard of the people' S republic of China QC/T307-;

if S is smaller than the preset value S, the vehicle is not in an emergency braking state, whole vehicle running parameter signals such as motor braking current, brake pipeline hydraulic pressure and vehicle speed are collected, and motor braking force F is obtained through calculation_mHydraulic braking force F_hAnd target braking force F_rAnd the vehicle control unit calculates a proportionality coefficient K according to a formula (2):

step three, a logic threshold control method is arranged in the vehicle control unit, and the vacuum degree value is controlled by the logic threshold control method, which specifically comprises the following steps:

(1) comparing K-1 with a threshold value K', wherein the threshold value is related to the precision of the whole vehicle controller and can be set to be 0.001;

(2) when K-1>When 0.001, the vehicle control unit controls the two electromagnetic valves to be not electrified, the first channel is closed, the second channel is opened, the electronic vacuum pump is started, the atmosphere in the front cavity of the vacuum booster is pumped into the air storage tank, the vacuum degree of the front cavity is improved, and the hydraulic braking force F is realized_hIncreased, motor braking force F_mThe size is reduced;

(3) when K-1 is less than or equal to 0.001, judging the size relationship between K-1 and-0.001:

when K-1<When the pressure of the air in the front cavity of the vacuum booster is reduced, the hydraulic braking force F is reduced, and the air storage tank is directly connected with the front cavity of the vacuum booster through the first electromagnetic valve_hReduced, electric machine braking force F_mEnlarging;

when K-1 is less than or equal to-0.001, only the second electromagnetic valve is electrified, both channels are closed at the moment, and the vacuum degree is not changed.

Step four, collecting a vehicle speed signal V by the whole vehicle, and if V is 0, ending the braking process; otherwise, repeating the steps one-three.

At present, a vacuum booster is generally adopted as servo boosting for passenger cars (including new energy vehicles) and light trucks, and the vacuum degree of the vacuum booster directly influences the boosting effect. Fig. 3 is a characteristic curve of the vacuum booster under different vacuum degrees, and it can be seen from fig. 3 that the higher the vacuum degree is, the larger the output force is for the same input force. The vacuum degree is adjusted through the steps, so that the control on the hydraulic braking force is realized, the coordinated distribution control on the electro-hydraulic composite braking force in the regenerative braking energy recovery link is finally realized, and the energy recovery efficiency is improved.

The present invention is not limited to the above-described embodiments, and any obvious modifications, substitutions or alterations can be made by those skilled in the art without departing from the spirit of the present invention.