CN110588359B - Control method and control device for braking energy recovery - Google Patents
Control method and control device for braking energy recovery Download PDFInfo
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- CN110588359B CN110588359B CN201910784094.9A CN201910784094A CN110588359B CN 110588359 B CN110588359 B CN 110588359B CN 201910784094 A CN201910784094 A CN 201910784094A CN 110588359 B CN110588359 B CN 110588359B
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- vacuum
- control method
- solenoid valve
- vacuum booster
- electromagnetic valve
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L7/00—Electrodynamic brake systems for vehicles in general
- B60L7/24—Electrodynamic brake systems for vehicles in general with additional mechanical or electromagnetic braking
- B60L7/26—Controlling the braking effect
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
- B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
- B60T13/66—Electrical control in fluid-pressure brake systems
- B60T13/72—Electrical control in fluid-pressure brake systems in vacuum systems or vacuum booster units
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- Engineering & Computer Science (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Power Engineering (AREA)
- Regulating Braking Force (AREA)
- Braking Systems And Boosters (AREA)
Abstract
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.
Description
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. However, the existing compound brake control technology mainly focuses on reducing or delaying the input of pedal force on the basis of not changing the structure of the traditional mechanical brake system so as to realize the maximum output of electric brake force, and in order to ensure the consistency and comfort of pedal feel, part of electric brake force has to be sacrificed 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.
Furthermore, the vacuum booster is a first channel from the first electromagnetic valve to the air storage tank, and the vacuum booster is a second channel from the second electromagnetic valve to the air storage tank.
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 through leads.
Further, the proportionality coefficient K is generated by the vehicle control unit according to the electric motor braking force F m Hydraulic braking force F h And target braking force F r The 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 through leads; 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 following detailed description, without limiting the scope of the invention 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 valve to form a second channel, 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; 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 m Hydraulic braking force F h And target braking force F r And 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', which is related to the vehicle control unit accuracy and may be set to 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 h Increased, motor braking force F m The 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 h Reduced, electric machine braking force F m Enlarging;
when K-1 is more 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 passenger car (including a new energy vehicle type) and a light truck generally adopt a vacuum booster as servo assistance, and the vacuum degree of the vacuum booster directly influences the assistance 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.
Claims (9)
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 all in signal connection with the vehicle control unit through wires.
7. 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.
8. The device for realizing the control method for recovering the braking energy, which is described in any one of claims 1 to 7, is characterized by comprising a vacuum booster, a gas 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 gas storage tank through a first electromagnetic valve, the front cavity of the vacuum booster is further 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 all in signal connection with a whole vehicle controller through conducting wires.
9. The apparatus of claim 8, 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.
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DE102005056681B3 (en) * | 2005-11-28 | 2007-01-18 | Lucas Automotive Gmbh | Braking force generator for brake assembly of e.g. hybrid vehicle, has electromechanical coupling which mechanically couples or uncouples pedal force input member to/from auxiliary force generating mechanism based on braking situation |
CN2880613Y (en) * | 2005-12-28 | 2007-03-21 | 比亚迪股份有限公司 | Brake vacuum booster for electric automobile |
CN200960918Y (en) * | 2006-08-31 | 2007-10-17 | 上海燃料电池汽车动力***有限公司 | Automobile electric liquid parallel hydraulic braking device |
CN101357630B (en) * | 2007-07-30 | 2011-09-07 | 比亚迪股份有限公司 | Brake vacuum booster device for electric automobile and control method thereof |
CN102180161A (en) * | 2011-04-21 | 2011-09-14 | 纽贝耳汽车(杭州)有限公司 | Electric auxiliary brake system of electric automobile |
CN102390275B (en) * | 2011-09-30 | 2013-07-17 | 江苏大学 | Electromagnetic braking device of electric automobile with function of energy recovery and work method thereof |
CN102490617B (en) * | 2011-11-14 | 2014-04-09 | 江苏大学 | Hybrid braking system with active auxiliary braking function and control method |
CN103693033A (en) * | 2012-09-27 | 2014-04-02 | 北汽福田汽车股份有限公司 | Vacuum boosting system, electric vehicle and vacuum boosting control method |
CN203198949U (en) * | 2013-04-26 | 2013-09-18 | 吉林大学 | Braking energy recovery system with pedal travel simulator |
CN104828051B (en) * | 2014-05-22 | 2018-01-19 | 北汽福田汽车股份有限公司 | The vacuum servo control system and its control method of hybrid vehicle |
CN104442414B (en) * | 2014-11-13 | 2017-03-22 | 奇瑞汽车股份有限公司 | Brake energy recycling control method |
CN206797355U (en) * | 2017-01-12 | 2017-12-26 | 九江学院 | A kind of automobile braking device |
CN107380152A (en) * | 2017-08-01 | 2017-11-24 | 风度(常州)汽车研发院有限公司 | A kind of vacuum boost system and electric automobile |
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