CN111301384A - Electro-hydraulic composite braking anti-lock system and control method thereof - Google Patents
Electro-hydraulic composite braking anti-lock system and control method thereof Download PDFInfo
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- CN111301384A CN111301384A CN202010101416.8A CN202010101416A CN111301384A CN 111301384 A CN111301384 A CN 111301384A CN 202010101416 A CN202010101416 A CN 202010101416A CN 111301384 A CN111301384 A CN 111301384A
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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
- B60T13/74—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 electrical assistance or drive
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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
- B60T13/58—Combined or convertible systems
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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
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/17—Using electrical or electronic regulation means to control braking
- B60T8/176—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS
- B60T8/1761—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS responsive to wheel or brake dynamics, e.g. wheel slip, wheel acceleration or rate of change of brake fluid pressure
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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
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/17—Using electrical or electronic regulation means to control braking
- B60T8/176—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS
- B60T8/1763—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS responsive to the coefficient of friction between the wheels and the ground surface
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- Engineering & Computer Science (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Regulating Braking Force (AREA)
Abstract
The invention provides an electro-hydraulic composite braking anti-lock braking system and a control method thereof, which comprise a hydraulic braking executing mechanism, a motor braking executing mechanism and an environment sensing and control decision mechanism, wherein the control mode of the hydraulic braking executing mechanism is 3-channel rear axle low-selection ABS, and the motor braking executing mechanism adopts different control modes according to different road conditions, is combined with the hydraulic braking executing mechanism and performs alternate compensation to brake wheels. The motor braking executing mechanism plays a role in quick adjustment and accurate adjustment in the whole adjusting and controlling process, and the hydraulic braking executing mechanism plays a role in providing large torque. The invention maximally utilizes the road surface adhesive force, and combines the advantages of the motor and the hydraulic actuating mechanism to meet the braking requirements under different working conditions.
Description
Technical Field
The invention belongs to the field of vehicle braking, and particularly relates to an electro-hydraulic compound braking anti-lock system and a control method thereof.
Background
Energy conservation, environmental protection and safety are three main subjects of development of the modern automobile industry, and the electric wheel automobile is one of the most concerned fields. The quantity of electric vehicles increases year by year, and the driving environment becomes more and more complex. This places higher demands on the driver and also challenges on the level of intelligence of the vehicle. In the driving safety of automobiles, the braking performance is the most important.
Under some emergency braking conditions, the motor braking mode adopted by the electric wheel automobile cannot provide enough required braking torque, and although the hydraulic braking mechanism can ensure that enough braking torque is generated under any working condition, the arrangement form is fixed (rear axle low-selection control), the hydraulic braking mechanism cannot be flexibly changed, and the ground adhesion force cannot be fully utilized, so that the electro-hydraulic composite braking system formed by hydraulic anti-lock braking and motor braking becomes one of the inevitable choices of the braking modes of the electric wheel automobile.
Disclosure of Invention
The invention provides an electro-hydraulic composite braking anti-lock system and a control method thereof, aiming at solving the problem that the ground adhesion cannot be fully utilized when the rear axle is subjected to low-selection control in the prior art.
The present invention achieves the above-described object by the following technical means.
An electro-hydraulic compound brake anti-lock system comprises a hydraulic brake executing mechanism, a motor brake executing mechanism and an environment sensing and control decision mechanism, wherein the environment sensing and control decision mechanism comprises an electronic control unit ECU, the electronic control unit ECU calculates the slip ratio of each wheel, and outputs required braking force to a hydraulic controller HCU and a motor controller MCU after analysis, judgment and amplification, the hydraulic controller HCU controls a brake pressure regulator to regulate the pressure in a hydraulic loop according to the required braking force, and the motor controller MCU controls a hub motor to work according to an expected torque value.
In the technical scheme, the working mode of the motor brake actuating mechanism comprises that four wheels are independently controlled to form a 4-channel ABS, two front wheels are independently controlled, the rear wheels form a 3-channel rear-axle low-selection ABS according to a low-selection control principle, two rear wheels are independently controlled, the front wheels form a 3-channel front-axle high-selection ABS according to a high-selection control principle, and two rear wheels are independently controlled, and the front wheels form a 3-channel front-axle low-selection ABS according to a low-selection control principle.
A control method of an electro-hydraulic composite braking anti-lock system is characterized in that a hydraulic braking executing mechanism and a motor braking executing mechanism are combined in different control modes according to different road conditions to brake wheels.
Further, the combination of the control modes specifically includes:
the first mode is as follows: when the vehicle passes through a uniform road surface, the working mode of the motor braking executing mechanism adopts any one mode;
and a second mode: when the vehicle runs from the road surface with low adhesion coefficient to the road surface with high adhesion coefficient, the working mode of the motor brake actuating mechanism adopts any one mode;
and a third mode: when the vehicle is driven to the opposite open circuit surface, the working mode of the motor brake actuating mechanism adopts 3-channel front axle low-selection ABS control or 3-channel rear axle low-selection ABS or 4-channel ABS;
and a fourth mode: when the front wheel and the rear wheel of the vehicle are in contact with the opposite open circuit surfaces, the working mode of the motor brake actuating mechanism adopts a 4-channel ABS;
and a fifth mode: when the vehicle runs out from a split road surface, the motor brake actuating mechanism adopts 3-channel front axle low-selection ABS or 3-channel front axle high-selection ABS or 4-channel ABS.
Furthermore, in the second mode, the hydraulic brake actuator and the motor brake actuator need to adjust the brake pressure distribution of the front axle and the rear axle, so that the brake force of the front wheel is increased, and the brake force of the rear wheel is reduced.
Furthermore, in the third mode, the motor brake actuator increases the braking force of the front wheel on the side with higher split road surface adhesion coefficient, the braking force of the two rear wheels is uniformly distributed, and the braking force of the rear wheel is different from the braking force of the two front wheels.
Furthermore, in the fourth mode, the motor brake actuator increases the wheel brake force on the side with higher split road surface adhesion coefficient, the wheel brake force on the two sides is different, and the front wheel brake force and the rear wheel brake force on the same side are different.
Furthermore, in the fifth mode, the motor brake actuator increases the braking force of the rear wheel on the side with higher split road surface adhesion coefficient, the braking force of the two front wheels is uniformly distributed, and the braking force of the front wheel is different from the braking force of the two rear wheels.
Furthermore, the control mode adopts a hydraulic brake actuating mechanism and an electric motor brake actuating mechanism to alternately compensate.
Further, the alternating compensation is specifically: the motor brake actuating mechanism limits the wheel slip rate, and the hydraulic brake actuating mechanism limits the wheel slip rate to be close to the ideal slip rate so as to accurately compensate the motor braking force; when the system shakes, if the wheel slip rate is not close to the ideal slip rate, the hydraulic braking force is readjusted, and then the motor braking force is accurately compensated.
Compared with the prior art, the invention has the following advantages:
(1) the working mode of the motor brake actuating mechanism comprises a 4-channel ABS formed by four independent wheels, a 3-channel rear-axle low-selection ABS formed by two front wheels and rear wheels according to a low-selection control principle, a 3-channel front-axle high-selection ABS formed by two rear wheels and front wheels according to a high-selection control principle, and a 3-channel front-axle low-selection ABS formed by two rear wheels and front wheels according to a low-selection control principle; the advantage that four wheel hub motors are accurate controllable alone of make full use of, nimble transform multiple arrangement form is in order to satisfy the braking demand under the different operating modes.
(2) When the vehicle wheel is braked, the hydraulic brake actuating mechanism and the motor brake actuating mechanism are combined in different control modes according to different road conditions, the respective advantages of the motor and the hydraulic actuating mechanism are combined, the respective defects are mutually compensated, and the road adhesion is maximally utilized under the condition that the wheels are not locked.
(3) When the hydraulic braking executing mechanism and the motor braking executing mechanism are combined in different control modes, the hydraulic braking executing mechanism and the motor braking executing mechanism alternately compensate, and the wheel slip rate is controlled quickly, accurately and reliably.
Drawings
The present invention will be better understood and appreciated more fully when considered in conjunction with the accompanying drawings. The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention in any way, in which:
FIG. 1 is a schematic diagram of a vehicle layout of an electro-hydraulic hybrid braking anti-lock system according to the present invention;
FIG. 2 is a schematic view of road conditions experienced by an electro-hydraulic composite braking anti-lock system in the working process of the invention;
FIG. 3 is a block diagram of the switching process of the arrangement and combination modes of the electro-hydraulic compound brake anti-lock system according to different working conditions;
fig. 4 is a specific control flow diagram of the control mode according to the present invention.
In the figure, 1-an electronic control unit ECU, 2-a wheel hub motor, 3-a brake pressure regulator, 4-a hydraulic brake master cylinder, 5-a wheel speed sensor, 6-a pressure sensor, 7-a hydraulic controller HCU, 8-a motor controller MCU, 9-a road surface with an adhesion coefficient of 0.4, 10-a road surface with an adhesion coefficient of 0.7, 11-a road surface with an adhesion coefficient of 0.8, and 12-a road surface with an adhesion coefficient of 0.2.
Detailed Description
The invention will be further described with reference to the following figures and specific examples, but the scope of the invention is not limited thereto.
An electro-hydraulic compound braking anti-lock braking system (ABS) comprises a hydraulic braking executing mechanism, a motor braking executing mechanism and an environment sensing and control decision mechanism.
The hydraulic brake actuating mechanism consists of a hydraulic brake master cylinder 4, a hydraulic controller HCU7, a brake pressure regulator 3 and a pressure sensor 6, wherein the hydraulic brake master cylinder 4 is connected with the hydraulic controller HCU7 through a lead, and the brake pressure regulator 3 is connected with the hydraulic controller HCU7 through a hydraulic pipeline; the hydraulic brake master cylinder 4 is arranged in a hydraulic circuit and is connected with a brake pedal through a brake booster, the brake pressure regulator 3 and the pressure sensor 6 are arranged in the hydraulic circuit, and the pressure sensor 6 is installed on a wheel hub; the brake pressure regulator 3 receives the instruction of the hydraulic controller HCU7, and increases, maintains and decreases the brake pressure by the action of the solenoid valve; the pressure sensor 6 is used for collecting the pressure of a wheel braking wheel cylinder and transmitting the pressure to the electronic control unit ECU 1; the hydraulic brake master cylinder 4 is in signal connection with the electronic control unit ECU 1.
The motor braking executing mechanism is composed of a motor controller MCU8 and a hub motor 2, the motor controller MCU8 is connected with the hub motor 2 through a lead, and the hub motor 2 is installed on a wheel and receives an instruction of the motor controller MCU8 to provide driving or braking torque for the wheel.
The environment sensing and control decision mechanism consists of a wheel speed sensor 5 and an electronic control unit ECU1, wherein the electronic control unit ECU1 is connected with the wheel speed sensor 5 through a signal line, and the electronic control unit ECU1 is connected with a hydraulic controller HCU7 and a motor controller MCU8 through a CAN bus; the wheel speed sensor 5 is arranged on a wheel hub and used for detecting the rotating speed of the wheel and providing a rotating speed signal to the electronic control unit ECU1, the electronic control unit ECU1 calculates the slip rate of each wheel, analyzes, judges and amplifies the slip rate, outputs the required braking force to the hydraulic controller HCU7 and the motor controller MCU8, and controls the braking pressure regulator 3 and the wheel hub motor 2 to work respectively through the hydraulic controller HCU7 and the motor controller MCU8, wherein the braking pressure regulator 3 is positioned in a hydraulic loop and regulates the pressure in the hydraulic loop according to the required braking force, and the wheel hub motor 2 works according to the expected torque value of the motor controller MCU8 to drive the vehicle to run.
The wheel slip rate is calculated by the formula:
s＝(v-ωr)/v
wherein: s is slip rate, v is current vehicle speed, ω is current wheel speed, and r is wheel radius. The current vehicle speed adopts a secondary big wheel speed method to match with speed change limitation, the wheel speeds are sorted to select the second big wheel speed as the vehicle speed, and if the vehicle speed at the moment is higher than the vehicle speed at the last moment by the maximum speed change limitation (the common value is 0.6g determined according to experience, namely the change value per second is not higher than 6m/s), the vehicle speed at the moment is corrected to be the vehicle speed at the last moment plus the speed change limitation.
The process of slip ratio analysis, discrimination and amplification is as follows: the slip ratio is compared with an ideal slip ratio (about 20%), and if the difference is larger than a certain threshold value (± 10% or so), the electronic control unit ECU1 enters a brake control mode selection state (see fig. 4). If the slip rates of the left wheel and the right wheel are different by too much (+/-10 percent or so), judging that the road surface is an open road surface at the moment; if the difference between the slip rates of the front wheel and the rear wheel is too large (about +/-20%), judging that the road surface is a butt joint road surface at the moment; if the four-wheel slip rates are not different (less than +/-5 percent or so), the road surface is judged to be a uniform road surface at the moment. And finally, amplifying the slip ratio obtained by calculation at the moment, and reducing the influence caused by continuous fluctuation.
A uniform road surface means that the adhesion coefficient of the entire road surface is unchanged or substantially unchanged (change value <0.15), a split road surface means that the adhesion coefficients of the left and right road surfaces are greatly different (change value >0.25), and a butt road surface means that the adhesion coefficient of the road surface is abruptly changed (change value >0.35) in the vehicle traveling direction.
Once the arrangement mode of the hydraulic brake actuating mechanism is determined, the arrangement mode cannot be changed, but when the motor brake actuating mechanism works, the four hub motors 2 are independently controllable, and the working modes are various. The method comprises the following steps: the motor brake actuating mechanism can adopt four wheels to independently control to form a 4-channel ABS; or two front wheels can be independently controlled, and the rear wheels form a 3-channel rear axle low-selection ABS according to a low-selection control principle; or two front wheels can be independently controlled, and the rear wheels form a 3-channel rear axle high-selection ABS according to a high-selection control principle; or two rear wheels can be independently controlled, and the front wheels form a 3-channel front axle high-selection ABS according to a high-selection control principle; or two rear wheels are independently controlled, and the front wheels form a 3-channel front-axle low-selection ABS according to a low-selection control principle. Wherein the low selection control principle is to ensure that wheels on the side with lower adhesion coefficient are not locked, and to select the pressure of a control system (the control system comprises a hydraulic brake actuating mechanism and a motor brake actuating mechanism); the high-selection control principle is to preferentially ensure that the wheel with higher adhesion coefficient is not locked, and the brake pressure is adjusted by keeping the same brake pressure between the wheel with lower adhesion coefficient and the wheel with higher adhesion coefficient. The following table shows different brake combination modes of the two sets of brake actuating mechanisms under different working conditions by taking a 3-channel type rear axle low-selection arrangement mode as an example. The rear axle high-selection ABS in the motor braking mode and the rear axle low-selection ABS in the hydraulic braking mode cannot coexist, and therefore are not listed in the table.
TABLE 1 combination of two sets of brake actuators
When the two sets of brake actuating mechanisms are combined in the following mode: the hydraulic braking actuating mechanism is a 3-channel rear axle low-selection ABS, the motor braking actuating mechanism is a 4-channel ABS, and the braking process is as follows:
when the vehicle is braked, the four wheel speed sensors 5 firstly send the measured rotating speed signals to the electronic control unit ECU1, and the ECU1 calculates the slip ratio of each wheel. The electronic control unit ECU1 analyzes, judges and amplifies the slip ratio, and combines the low selection control principle of the vehicle to calculate the braking force demand (the calculation method is that on the basis of calculating the braking force demand by the original brake pedal, the deviation of the slip ratio and the ideal slip ratio (20%) is taken into consideration, when the deviation is large, the braking force demand is properly reduced according to PID adjustment), and a demand instruction is transmitted to the hydraulic controller HCU7 and the motor controller MCU8 through a CAN bus, and the hydraulic controller HCU7 controls the braking pressure regulator 3 through PWM to regulate the pressure in a pipeline until the demand value is met; the motor controller MCU8 sends out instructions to control the in-wheel motor 2 to execute corresponding actions, and the vehicle starts to decelerate. When the braking force demand is calculated, the hydraulic braking executing mechanism is always controlled by the front wheel independently and controlled by the rear axle low selection (the prior art). Because the motor braking executing mechanism can be flexibly adjusted on the basis of the hydraulic braking executing mechanism, the road adhesion is utilized to the maximum extent, different modes of motor braking are switched by a torque control command directly sent to the hub motor 2 by each motor controller MCU8, and the control process of the specific torque command is the prior art.
When the combination mode of the two sets of brake actuators is other, the specific braking process is similar to the above-described braking process, and details are not repeated herein, except that different torque instructions are sent to the corresponding hub motors 2 by the motor controllers MCU8 in different motor brake mechanism arrangement modes.
Taking the vehicle running according to the road condition in fig. 2 as an example, the combined braking modes adopted by the hydraulic braking actuator and the motor braking actuator are described in detail one by one with reference to the control block diagram in fig. 3, in fig. 2, the vehicle firstly runs through a uniform road surface 9 and a road surface 10, and then runs through a split road surface (composed of a road surface 11 and a road surface 12), and the adhesion coefficient of the road surface 9 is 0.4, the adhesion coefficient of the road surface 10 is 0.7, the adhesion coefficient of the road surface 11 is 0.8, and the adhesion coefficient of the road surface 12 is 0.2.
When the vehicle passes through a uniform road surface, the hydraulic braking executing mechanism adopts a mode of independently controlling the front wheels and controlling the low selection of the rear axle; the motor brake actuating mechanism adopts a four-wheel independent control mode, but the adhesion coefficients of the grounding points of the left wheel and the right wheel are almost the same due to the fact that the road surface is uniform, so that the four-wheel brake force can be considered to be uniformly distributed based on the axle load. In this case, the effect is the same regardless of which arrangement the motor brake actuator adopts.
When a vehicle runs from a road surface 9 to a road surface 10, two front wheels contact the road surface 10, and two rear wheels contact the road surface 9, the hydraulic brake actuating mechanism and the motor brake actuating mechanism need to adjust the brake pressure distribution of the front shaft and the rear shaft, the brake force of the front wheels is increased, and the brake force of the rear wheels is reduced. In this case, the effect is the same regardless of which arrangement the motor brake actuator adopts.
When a vehicle runs from the road surface 10 to a split road surface (composed of the road surfaces 11 and 12), the hydraulic braking executing mechanism and the motor braking executing mechanism adopt a method of independently controlling front wheels, so that the front wheels on one side of the road surface 11 have larger braking force, and the road surface adhesive force is fully utilized on the premise of no locking. At the moment, the two rear wheels still adopt the control of uniform distribution of braking force, but the braking force of the two rear wheels is adjusted according to the slip ratio of the two rear wheels, which is different from the braking force of the two front wheels. In this case, the motor brake actuator can adopt a 3-channel front axle low-selection ABS or a 3-channel rear axle low-selection ABS or a 4-channel ABS.
When the front wheels and the rear wheels of the vehicle are in contact with an opposite-opening road surface (consisting of the road surfaces 11 and 12), the hydraulic braking executing mechanism and the motor braking executing mechanism adopt a method of independently controlling the front wheels, so that the wheels on one side of the road surface 11 have larger braking force; because the hydraulic brake actuating mechanism can not independently control the rear wheels, only the two rear wheels can have the same braking force, and the wheels on one side of the road surface 11 can not fully utilize the road surface adhesive force; therefore, the motor brake actuator should increase the braking force on the wheel on the side of the road surface 11, so that the braking forces of the front wheel and the rear wheel on the sides of the road surface 11 and the road surface 12 are respectively the same, and the braking forces of the two rear wheels are different. In this case, the motor brake actuator can only adopt a 4-channel ABS.
When the vehicle is driven out from a split road surface, in order to prevent wheels on one side of the road surface 12 from locking, the hydraulic brake actuating mechanism adopts a low-selection control mode to ensure that the wheels on the side with higher adhesion coefficients (the road surface 11) and the wheels on the side of the road surface 12 have the same small braking force, and at the moment, because the adhesion coefficients at the grounding points of the left wheel and the right wheel have larger difference, the road adhesion can not be fully utilized by adopting the single control mode; the motor brake actuating mechanism can be utilized to apply extra motor brake force to the rear wheel on the side with higher adhesion coefficient, namely, the hydraulic rear axle low-selection control and motor four-wheel independent control mode is adopted, and the ground adhesion is utilized to the maximum extent on the premise of no locking. The braking force of the two front wheels is uniformly distributed, but is different from the braking force of the two rear wheels, and the braking force of the two front wheels is adjusted according to the slip ratio of the two front wheels. In this case, the motor brake actuator can adopt a 3-channel front axle low-selection ABS or a 3-channel front axle high-selection ABS or a 4-channel ABS.
The four brake control modes in table 1 can be switched according to the specific situation of the road surface, but for a certain wheel, there may be both hydraulic brake and motor brake, so after a suitable brake mode is decided, the specific control mode of the two brake actuators needs to be considered, different from the conventional control mode, at this time, the two actuators need to be alternately compensated by adopting a "cyclic compensation method", specifically as follows:
(1) firstly, the motor is braked at the beginning by utilizing the advantage of quick response of the motor, so that the wheel slip rate is quickly limited;
(2) if the required braking force is in the regulation range of the motor braking executing mechanism, the motor braking force is directly subjected to fine adjustment, and the wheel braking torque is accurately regulated and controlled in real time by the hub motor 2 along with the fluctuation of the slip ratio (Yuan. If the required braking force exceeds the regulation range of the motor braking executing mechanism, then the intervention of hydraulic braking is carried out by utilizing the characteristic that the hydraulic braking executing mechanism can output large torque, the slip rate at the moment is further limited to be close to the ideal slip rate, and finally the braking force of the motor is changed, so that the effect of compensating the system jitter and the slip rate fluctuation is achieved.
3. Because the hydraulic brake mechanism has the defects of system jitter and the like, whether the slip ratio is always kept near an ideal value allowable range (20% +/-5%) needs to be judged, if the slip ratio exceeds the limit value at a certain moment, the braking force of the hydraulic brake actuating mechanism is readjusted, and the step (2) is repeated, and the two brake actuating mechanisms are continuously and alternately adjusted until the system state and the control effect meet the requirements.
In a word, the motor braking actuating mechanism plays a role in quick adjustment and accurate adjustment in the whole adjusting and controlling process, and the hydraulic braking actuating mechanism plays a role in providing large torque. The method can provide the advantages that a 'simultaneous braking strategy' or a 'motor braking before hydraulic braking strategy' in the conventional electro-hydraulic composite braking can not be provided, and achieves rapidness, accuracy and reliability in the control of the slip ratio of each wheel. As shown in fig. 4.
The present invention is not limited to the above-described embodiments, and any obvious improvements, substitutions or modifications can be made by those skilled in the art without departing from the spirit of the present invention.
Claims (10)
1. The electro-hydraulic compound brake anti-lock system is characterized by comprising a hydraulic brake executing mechanism, a motor brake executing mechanism and an environment sensing and control decision mechanism, wherein the environment sensing and control decision mechanism comprises an electronic control unit ECU (1), the electronic control unit ECU (1) calculates the slip ratio of each wheel, after analysis, judgment and amplification are carried out, required braking force is output to a hydraulic controller HCU (7) and a motor controller MCU (8), the hydraulic controller HCU (7) controls a brake pressure regulator (3) to regulate the pressure in a hydraulic loop according to the required braking force, and the motor controller MCU (8) controls a hub motor (2) to work according to an expected torque value.
2. The electro-hydraulic compound brake anti-lock system according to claim 1, wherein the operation modes of the motor brake actuator include four wheels independently controlled to form a 4-channel ABS, two front wheels independently controlled to form a 3-channel rear axle low-selection ABS according to a low-selection control principle, two rear wheels independently controlled to form a 3-channel front axle high-selection ABS according to a high-selection control principle, and two rear wheels independently controlled to form a 3-channel front axle low-selection ABS according to a low-selection control principle.
3. A control method of an electro-hydraulic compound brake anti-lock braking system according to any one of claims 1-2, wherein the hydraulic brake actuator and the motor brake actuator are combined in different control modes according to different road conditions to brake the wheels.
4. The control method of an electro-hydraulic compound brake anti-lock system according to claim 3, wherein the combination of control modes is specifically:
the first mode is as follows: when the vehicle passes through a uniform road surface, the working mode of the motor braking executing mechanism adopts any one mode;
and a second mode: when the vehicle runs from the road surface with low adhesion coefficient to the road surface with high adhesion coefficient, the working mode of the motor brake actuating mechanism adopts any one mode;
and a third mode: when the vehicle is driven to the opposite open circuit surface, the working mode of the motor brake actuating mechanism adopts 3-channel front axle low-selection ABS control or 3-channel rear axle low-selection ABS or 4-channel ABS;
and a fourth mode: when the front wheel and the rear wheel of the vehicle are in contact with the opposite open circuit surfaces, the working mode of the motor brake actuating mechanism adopts a 4-channel ABS;
and a fifth mode: when the vehicle runs out from a split road surface, the motor brake actuating mechanism adopts 3-channel front axle low-selection ABS or 3-channel front axle high-selection ABS or 4-channel ABS.
5. The method of claim 4, wherein in the second mode, the hydraulic brake actuator and the motor brake actuator are required to adjust the brake pressure distribution of the front and rear axles to increase the front wheel brake force and decrease the rear wheel brake force.
6. The method of claim 4, wherein in the third mode, the motor brake actuator increases the braking force to the front wheel on the side with higher road-surface-open adhesion coefficient, the braking force is uniformly distributed to the two rear wheels, and the braking force to the rear wheels is different from the braking force to the two front wheels.
7. The method of claim 4, wherein in the fourth mode, the motor brake actuator increases the braking force of the wheels on the side with higher road-open adhesion coefficient, the braking forces of the wheels on both sides are different, and the braking forces of the front and rear wheels on the same side are the same.
8. The method of claim 4, wherein in the fifth mode, the motor brake actuator increases the braking force to the rear wheel on the side with higher open road adhesion coefficient, the two front wheels are uniformly distributed, and the braking force to the front wheels is different from the braking force to the two rear wheels.
9. The control method of an electro-hydraulic compound brake anti-lock system according to any one of claims 4 to 8, wherein the control mode employs alternate compensation of a hydraulic brake actuator and an electric motor brake actuator.
10. The control method of an electro-hydraulic compound brake anti-lock system according to claim 9, wherein the alternate compensation is specifically: the motor brake actuating mechanism limits the wheel slip rate, and the hydraulic brake actuating mechanism limits the wheel slip rate to be close to the ideal slip rate so as to accurately compensate the motor braking force; when the system shakes, if the wheel slip rate is not close to the ideal slip rate, the hydraulic braking force is readjusted, and then the motor braking force is accurately compensated.
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| CN202010101416.8A CN111301384B (en) | 2020-02-19 | 2020-02-19 | Electro-hydraulic composite braking anti-lock system and control method thereof |
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| CN202010101416.8A CN111301384B (en) | 2020-02-19 | 2020-02-19 | Electro-hydraulic composite braking anti-lock system and control method thereof |
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| CN111301384B CN111301384B (en) | 2021-07-20 |
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| CN202010101416.8A Active CN111301384B (en) | 2020-02-19 | 2020-02-19 | Electro-hydraulic composite braking anti-lock system and control method thereof |
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| CN (1) | CN111301384B (en) |
Cited By (2)
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| CN110588608A (en) * | 2018-06-12 | 2019-12-20 | 罗伯特·博世有限公司 | Method and device for brake control |
| CN112046456A (en) * | 2020-08-19 | 2020-12-08 | 宝能(广州)汽车研究院有限公司 | Anti-lock control method and control device for electro-hydraulic composite braking |
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| CN110588608B (en) * | 2018-06-12 | 2023-05-02 | 罗伯特·博世有限公司 | Method and device for braking control |
| CN112046456A (en) * | 2020-08-19 | 2020-12-08 | 宝能(广州)汽车研究院有限公司 | Anti-lock control method and control device for electro-hydraulic composite braking |
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| CN111301384B (en) | 2021-07-20 |
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