CN114771487A - Integrated electronic hydraulic brake system and control method thereof - Google Patents
Integrated electronic hydraulic brake system and control method thereof Download PDFInfo
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- CN114771487A CN114771487A CN202210400404.4A CN202210400404A CN114771487A CN 114771487 A CN114771487 A CN 114771487A CN 202210400404 A CN202210400404 A CN 202210400404A CN 114771487 A CN114771487 A CN 114771487A
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Classifications
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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
- B60T13/745—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 acting on a hydraulic system, e.g. a master cylinder
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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
- B60T7/00—Brake-action initiating means
- B60T7/02—Brake-action initiating means for personal initiation
- B60T7/04—Brake-action initiating means for personal initiation foot actuated
- B60T7/042—Brake-action initiating means for personal initiation foot actuated by electrical means, e.g. using travel or force sensors
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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
- B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
- B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
- B60T8/40—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition comprising an additional fluid circuit including fluid pressurising means for modifying the pressure of the braking fluid, e.g. including wheel driven pumps for detecting a speed condition, or pumps which are controlled by means independent of the braking system
- B60T8/4072—Systems in which a driver input signal is used as a control signal for the additional fluid circuit which is normally used for braking
- B60T8/4081—Systems with stroke simulating devices for driver input
Abstract
The invention provides an integrated electronic hydraulic brake system, which comprises an electronic pedal module, an electronic control unit, a main cylinder pressure building module and a hydraulic control module, wherein the electronic pedal module is connected with the electronic control unit through a hydraulic control module; the electronic pedal module comprises a brake pedal, an input push rod, a pedal sensor group and a pedal brake feedback simulator; the master cylinder pressure building module comprises a brake motor, a motor controller, a speed reducing mechanism and a brake motor sensor group, the hydraulic pressure control module comprises a brake master cylinder, a piston push rod, a brake wheel cylinder, a wheel cylinder pressure sensor, a brake, a liquid storage tank and a two-way proportional valve, and the electronic control unit is respectively electrically connected with the pedal sensor group, the pedal brake feedback simulator, the motor controller, the brake motor sensor group, the two-way proportional valve and the wheel cylinder pressure sensor. The invention further provides a control method of the integrated electronic hydraulic brake system. The invention is suitable for various braking conditions, and has the advantages of fast braking reaction and good braking effect.
Description
Technical Field
The invention belongs to the technical field of electronic hydraulic braking systems, and particularly relates to an integrated electronic hydraulic braking system and a control method thereof.
Background
With the gradual popularization of electric vehicles, related technologies are rapidly developing to develop an electronic hydraulic brake system based on a traditional hydraulic brake, and the electronic hydraulic brake system is widely applied to various new energy vehicles.
The electronic hydraulic brake system breaks the mechanical connection between the brake pedal and the hydraulic cylinder, adopts the electronic brake pedal to replace the traditional brake pedal mechanism, and the electronic brake pedal contains the displacement sensor and the force sensor, can accurately sense the severity of the control pedal of a driver, and converts the severity into an electric signal to be transmitted to the electronic control unit.
The existing automatic emergency braking system (AEB) control strategy mainly considers the technical innovation of an algorithm level, the cooperation execution research of a bottom-layer execution mechanism is few, and the problems that the cooperation degree of the control strategy and the execution mechanism is low, and the efficiency cannot be further improved exist. The Chinese patent application No. 202010531692.8 proposes a braking method for an automatic emergency braking system aiming at different movement states of an obstacle, but the method mainly considers the problem of a threshold value of a control strategy and does not fully consider the specific execution of an execution mechanism. Although specific control strategies are considered in the conventional automatic emergency braking method and system for the electric automobile, the control strategies are single, and the braking effect on different working conditions cannot be better. Therefore, a new technical solution is needed to solve the above problems.
Disclosure of Invention
In order to solve the technical problems, the invention provides an integrated electronic hydraulic brake system and a control method thereof, which aim to solve the problems that in the prior art, the control strategy and the execution mechanism are low in matching degree, and the efficiency cannot be further improved.
In order to achieve the technical purpose and achieve the technical requirements, the invention adopts the technical scheme that: an integrated electronic hydraulic brake system comprises an electronic pedal module, a main cylinder pressure building module, a hydraulic control module and an electronic control unit;
the electronic pedal module comprises a brake pedal, an input push rod, a pedal sensor group and a pedal brake feedback simulator connected with the input push rod, wherein the sensor group outputs a pedal displacement signal and a pedal force signal;
the master cylinder pressure building module comprises a brake motor, a motor controller, a speed reducing mechanism and a brake motor sensor group, wherein the brake motor sensor group outputs a rotating speed signal and a torque signal of the brake motor;
the hydraulic pressure control module comprises a brake master cylinder, a piston push rod connected with the brake master cylinder, a brake wheel cylinder, a wheel cylinder pressure sensor, a brake, a liquid storage tank and a bidirectional proportional valve, wherein the liquid storage tank is connected with the brake master cylinder through an oil pipe;
the brake motor output shaft is connected with the input end of the speed reducing mechanism, the output end of the speed reducing mechanism is connected with the piston push rod, and the electronic control unit is respectively and electrically connected with the pedal sensor group, the pedal brake feedback simulator, the motor controller, the brake motor sensor group, the two-way proportional valve and the wheel cylinder pressure sensor.
As a preferred technical scheme, the pedal sensor group comprises a pedal displacement sensor and a pedal force sensor, the pedal displacement sensor and the pedal force sensor are arranged on an input push rod, the brake motor sensor group comprises a rotating speed sensor and a torque sensor, and the pedal displacement sensor, the pedal force sensor, the rotating speed sensor and the torque sensor are electrically connected with each other through an electronic control unit.
As a preferred technical scheme, a first cavity and a second cavity are arranged in the brake master cylinder, the first cavity and the second cavity are respectively connected with the liquid storage tank through oil pipes, the brake wheel cylinder comprises a left front wheel cylinder, a left rear wheel cylinder, a right front wheel cylinder and a right rear wheel cylinder, the first cavity is communicated with the left rear wheel cylinder and the right front wheel cylinder, the second cavity is communicated with the left front wheel cylinder and the right rear wheel cylinder, the left front wheel cylinder, the left rear wheel cylinder, the right rear wheel cylinder and the right rear wheel cylinder are respectively connected with 1 brake through oil pipes, and each brake is correspondingly provided with 1 two-way proportional valve.
The invention also provides a control method of the integrated electronic hydraulic brake system, which comprises the following steps:
step 1: when a driver encounters an emergency situation during driving, a pedal displacement signal and a pedal force signal are input to an input push rod through an electronic brake pedal, a pedal sensor group collects the pedal displacement signal and the pedal force signal and transmits the pedal displacement signal and the pedal force signal to an electronic control unit, an upper layer controller is arranged on a vehicle, and the upper layer controller transmits a vehicle speed signal, a vehicle distance signal and an obstacle distance signal to the electronic control unit;
and 2, step: the method comprises the steps that an electronic control unit judges the braking intention of a driver according to received pedal displacement signals and pedal force signals, the electronic control unit generates a pedal braking feedback simulator control instruction according to the braking intention of the driver, the pedal braking feedback simulator generates corresponding pedal damping feeling according to the control instruction to feed back the braking behavior of the driver, the emergency level of vehicle braking is judged based on the enhanced distance collision time ETTC according to the received vehicle speed and the distance between the vehicle and an obstacle, if emergency braking is not needed, the conventional braking operation of the driver is not interfered, if emergency braking is needed, the emergency level is divided into three levels, namely an emergency level three, an emergency level two and an emergency level one, and the next step is carried out according to different emergency levels;
and 3, step 3: if the emergency level is judged to be the third emergency level, the displacement of the brake motor in the unit stroke of the electronic brake pedal is changed, namely the rotation coefficient alpha of the brake motor is changed, so that the brake operation of a driver is assisted, and the emergency brake purpose is achieved; after receiving the instruction signal of the electronic control unit, the motor controller controls the brake motor to output torque and move to the speed reducing mechanism, and the speed reducing mechanism extrudes brake fluid in the brake master cylinder by driving the piston push rod to improve the brake pressure in the brake master cylinder, so that the pressure intensity is established for the brake master cylinder;
and 4, step 4: if the emergency level II is judged, the electronic control unit controls the two-way proportional valve to increase the opening degree and instantly increase the pressure of the brake wheel cylinder so as to achieve the purpose of emergency braking; the wheel cylinder pressure sensor collects the pressure of each brake wheel cylinder and transmits a brake wheel cylinder pressure signal to the electronic control unit, and the electronic control unit compares the actual brake wheel cylinder pressure with the target brake wheel cylinder pressure and controls each two-way proportional valve to effectively adjust the pressure of each brake wheel cylinder;
and 5: if judging that the emergency level is first, the electronic control unit controls the brake motor to quickly increase the pressure of the brake master cylinder and simultaneously controls the two-way proportional valve to increase the opening degree, the electronic control unit simultaneously sends control signals to the motor controller and the two-way proportional valve to control the quick establishment of the pressure of the brake master cylinder and expand the opening degree of the two-way proportional valve to improve the proportion of the pressure of the brake master cylinder to the brake wheel cylinders, the brake motor sensor group collects the rotating speed and torque signals of the brake motor and transmits the signals to the electronic control unit, the electronic control unit calculates the pressure of the actual brake master cylinder and compares the pressure with the pressure of the target brake master cylinder to calculate the pressure difference, the motor controller further compensates the pressure difference, the wheel cylinder pressure sensor collects the pressure of each brake wheel cylinder and transmits the pressure signals of the brake wheel cylinders to the electronic control unit, and the electronic control unit compares the actual brake wheel cylinder pressure with the pressure of the target brake wheel cylinders, and controlling each two-way proportional valve to effectively regulate the pressure of a single brake wheel cylinder.
As a preferred technical solution, the regular braking operation in step 2 is expressed by a braking motor rotation coefficient α, and the braking motor rotation coefficient α is calculated by the following expression:
α＝lmaster cylinder/lPedal (1)
In the formula 1, lMaster cylinderMaximum stroke of piston rod of main cylinderPedalThe maximum stroke of the electronic brake pedal.
As a preferable technical solution, the reinforced collision distance time ETTC in the step 2 is a determination condition, and a calculation expression thereof is:
in formula 2, Xrel、vrelAnd arelRespectively, relative distance, relative speed and relative acceleration of the vehicle relative to the preceding vehicle, Xb、vbAnd aaPosition, speed and acceleration of the preceding vehicle, Xa、vaAnd abThe position and the speed of the vehicle; if ETTC > TnWhen the vehicle is safe, the conventional braking is executed; if ETTC is less than or equal to TnIf so, judging as an emergency level three; if Tb2≤ETTC≤Tb1If so, judging as an emergency level two; if ETTC is less than or equal to Tb2If so, judging as an emergency level one; definition of Tn、Tb1And Tb2The value is determined by the following formula:
preferably, the pedal brake feedback simulator generates a feedback force FfbThe calculation expression of (a) is:
in equation 4, a is vehicle deceleration, M is vehicle mass, AmainThe master cylinder cross-sectional area, R tire radius, μbFactor of brake effectiveness, AwCross sectional area of wheel cylinder, rbIs the effective radius of the brake and C is the comfort factor of the brake pedal.
As the preferred technical scheme, the motor controller adopts a closed-loop controller, a brake motor sensor group acquires the rotating speed and the torque of a brake motor, and the rotating speed and the torque are processed by a gain coefficient matrix K1Returning data to the electronic control unit, and calculating the actual braking motor rotation coefficient alpha in the electronic control unitrealAnd comparing the actual rotation coefficient with the target rotation coefficient of the brake motor to obtain the difference value between the actual rotation coefficient and the target rotation coefficient of the brake motor:
eα＝α-αreal×K1 (5)
and taking the calculated difference value as the input of the closed-loop control of the brake motor, wherein the output model is as follows:
in the formula 6, KpαIs a proportionality coefficient, TαIs a differential constant, u0αAre control constants.
Preferably, the opening of the two-way proportional valve 8 is controlled by a closed-loop controller, and the wheel cylinder pressure sensor collects the pressure in the wheel cylinder and passes through a gain coefficient K2Returning data to the electronic control unit, and comparing the data with the target brake wheel cylinder pressure to obtain the pressure difference between the actual brake wheel cylinder pressure and the target brake wheel cylinder:
ew＝P-Preal×K2 (7)
and taking the calculated pressure difference as the input of the opening closed-loop control of the bidirectional proportional valve, wherein the output model is as follows:
in formula 8, LPIs a proportionality coefficient, TPIs a differential constant, v0PIs a control constant.
As a preferred technical scheme, in the step 5, the output torque of the brake motor is controlled by adopting a closed-loop controller, a brake motor sensor group collects the output torque of the brake motor, transmits data to an electronic control unit, compares the data with the target output torque of the brake motor, and performs closed-loop control on the output torque of the brake motor by using the closed-loop controller, wherein the control logic and expression of the closed-loop controller are the same as those of the formula 5 and the formula 6, and the control target is changed into the output torque of the brake motor from the rotation coefficient of the brake motor.
The beneficial effects of the invention are:
the characteristic of quick response and independent adjustment of the bidirectional proportional valve are fully utilized, a single control path from top to bottom in the original automatic emergency braking control is improved, and the electronic control unit sends a control instruction to the pedal braking feedback simulator according to the received pedal displacement signal and the pedal force signal; processing and analyzing the received pedal displacement signal and pedal force signal, analyzing the emergency braking condition of the vehicle, sending a control command to a motor controller according to the analysis result, wherein the control command comprises the intensity, the frequency and the direction of a brake motor input signal so as to build main cylinder pressure, and sending a control command to a bidirectional proportional valve so as to adjust the hydraulic pressure of a wheel cylinder; the electronic control unit receives signals of the rotating speed and the torque of the feedback brake motor of the rotating speed sensor and the torque sensor and carries out negative feedback adjustment on control signals output to the motor controller; the electronic control unit finely adjusts the pressure of the wheel cylinder by controlling the two-way proportional valve according to signals of the wheel cylinder pressure sensor, the braking effect of the whole system is good, the response time of automatic emergency braking is reduced, the system is suitable for various braking conditions, the control method is logical and reasonable, the system is suitable for various complex running states, the application range is wider, and the problem of control strategy singleness is solved.
Drawings
FIG. 1 is a block diagram of an integrated electro-hydraulic brake system of the present invention;
FIG. 2 is a control schematic of the control method of the present invention;
FIG. 3 is a control flow diagram of emergency level three of the automatic emergency braking control method of the present invention;
FIG. 4 is a control flow diagram of emergency level two in the automatic emergency braking control method of the present invention;
FIG. 5 is a control flow diagram of emergency level one in the automatic emergency braking control method of the present invention;
in fig. 1-5, a, an electronic pedal module; B. a master cylinder pressure building module; C. a hydraulic pressure control module; 1. an electronic brake pedal; 2. an input push rod 3 and a pedal brake feedback simulator; 4. a pedal displacement sensor; 5. a pedal force sensor; 6. an electronic control unit; 7. a wheel cylinder pressure sensor; 8. a two-way proportional valve; 9. a brake; 10. a liquid storage tank; 11. a brake master cylinder; 12. a speed reduction mechanism; 13. a rotational speed sensor; 14. braking the motor; 15. a torque sensor; 16. a motor controller.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
Referring to fig. 1-5, an integrated electronic hydraulic brake system includes an electronic pedal module a, a master cylinder pressure building module B, a hydraulic pressure control module C, and an electronic control unit 6;
the electronic pedal module a includes: the brake system comprises an electronic brake pedal 1, an input push rod 2, a pedal sensor group and a pedal brake feedback simulator 3; the pedal sensor group comprises a pedal displacement sensor 4 and a pedal force sensor 5, and the electronic brake pedal 1 is connected with the input push rod 2; the input push rod 2 is mechanically connected with the pedal brake feedback simulator 3; the pedal displacement sensor 4 and the pedal force sensor 5 are fixedly arranged on the input push rod 2; the pedal displacement sensor 4, the pedal force sensor 5 and the pedal brake feedback simulator 3 are connected with the electronic control unit 6 through a bus;
the master cylinder pressure buildup module B includes: the system comprises a motor controller 16, a brake motor 14, a speed reducing mechanism 12 and a brake motor sensor group; the braking motor sensor group comprises a rotating speed sensor 13 and a torque sensor 15, and the electronic control unit 6, the motor controller 16 and the braking motor 14 are electrically connected in sequence; the output shaft of the brake motor 14 is mechanically connected with the speed reducing mechanism 12; the rotating speed sensor 13 is used for measuring the output rotating speed of the brake motor 14, the torque sensor 15 is used for measuring the output torque of the brake motor 14, and the rotating speed sensor 13 and the torque sensor 15 are connected with the electronic control unit 6 through a bus;
the hydraulic pressure control module C includes: the brake system comprises a piston push rod, a brake master cylinder 11, a liquid storage tank 10, a two-way proportional valve 8, a brake wheel cylinder, a wheel cylinder pressure sensor 7 and a brake 9; the piston push rod is connected with the speed reducing mechanism 12 of the main cylinder pressure building module B through a gear rack or a worm and gear, and the rotary motion is converted into linear motion; the piston push rod is mechanically connected with the brake master cylinder 11; further, a first cavity and a second cavity are arranged in the brake master cylinder 11, the first cavity and the second cavity are respectively connected with the liquid storage tank 10 through oil pipes, the brake wheel cylinder comprises a left front wheel cylinder, a left rear wheel cylinder, a right front wheel cylinder and a right rear wheel cylinder, the first cavity is communicated with the left rear wheel cylinder and the right front wheel cylinder, the second cavity is communicated with the left front wheel cylinder and the right rear wheel cylinder, the left front wheel cylinder, the left rear wheel cylinder, the right rear wheel cylinder and the right rear wheel cylinder are respectively connected with 1 brake 9 through oil pipes to provide brake pressure, and each brake 9 is correspondingly provided with 1 two-way proportional valve 8; the wheel cylinder pressure sensor 7 is fixed at the inlet of an oil pipe of the brake wheel cylinder and is electrically connected with the electronic control unit 6; the brake cylinders are not labeled in the figures;
the electronic control unit 6 is electrically connected with the pedal displacement sensor 4, the pedal force sensor 5, the pedal brake feedback simulator 3, the motor controller 16, the rotating speed sensor 13, the torque sensor 15, the two-way proportional valve 8 and the wheel cylinder pressure sensor 7 respectively; generally, an electric vehicle is provided with an upper controller, and the upper controller transmits data information of vehicle speed and vehicle distance to the electronic control unit 6.
The invention also provides a control method of the integrated electronic hydraulic brake system, which comprises the following steps:
step 1: when a driver encounters an emergency during running, a pedal displacement signal and a pedal force signal are input to the input push rod 2 through the electronic brake pedal 1, a pedal sensor group collects the pedal displacement signal and the pedal force signal and transmits the signals to the electronic control unit 6, an upper controller is arranged on a vehicle, and the upper controller transmits a vehicle speed signal, a vehicle distance signal and an obstacle distance signal to the electronic control unit 6;
and 2, step: the electronic control unit 6 judges the braking intention of a driver according to the received pedal displacement signal and the pedal force signal, the electronic control unit 6 generates a control instruction of a pedal braking feedback simulator 3 according to the braking intention of the driver, the pedal braking feedback simulator 3 generates corresponding pedal damping feeling according to the control instruction and feeds back the braking action of the driver, the emergency level of the vehicle braking is judged based on the strengthened distance collision time ETTC according to the received signals of the speed, the distance and the distance of an obstacle, if the emergency braking is not needed, the conventional braking operation of the driver is not interfered, if the emergency braking is needed, the emergency level is divided into three levels, namely an emergency level three, an emergency level two and an emergency level one, and the next step is carried out according to different emergency levels;
and 3, step 3: if the emergency level is judged to be the third, the displacement of the brake motor 14 in the unit stroke of the electronic brake pedal 1 is changed, namely the rotation coefficient alpha of the brake motor is changed, so as to assist the driver in braking operation and achieve the purpose of emergency braking; after receiving the instruction signal of the electronic control unit 6, the motor controller 16 controls the brake motor 14 to output torque and move to the speed reducing mechanism 12, and the speed reducing mechanism 12 squeezes the brake fluid in the brake master cylinder 11 by driving the piston push rod to increase the brake pressure in the brake master cylinder 11, so as to build pressure on the brake master cylinder 11;
and 4, step 4: if the emergency level II is judged, the electronic control unit 6 controls the two-way proportional valve 8 to increase the opening degree, and instantly increases the pressure of the brake wheel cylinder by utilizing the characteristic of short transmission distance from the brake wheel cylinder so as to achieve the purpose of emergency braking; the electronic control unit 6 sends a control signal to the two-way proportional valve 8 to control the opening degree of the valve so as to control the pressure in the brake wheel cylinder; the wheel cylinder pressure sensor 7 collects the pressure of each brake wheel cylinder and transmits a brake wheel cylinder pressure signal to the electronic control unit 6, and the electronic control unit 6 compares the actual brake wheel cylinder pressure with the target brake wheel cylinder pressure and controls each two-way proportional valve 8 and the brake 9 to effectively adjust each brake wheel cylinder pressure;
and 5: if judging that the emergency level is first, the electronic control unit 6 controls the brake motor 14 to quickly increase the pressure of the brake master cylinder 11 and simultaneously controls the bidirectional proportional valve 8 to increase the opening degree, the electronic control unit 6 simultaneously sends control signals to the motor controller 16 and the bidirectional proportional valve 8 to control the quick establishment of the pressure of the brake master cylinder 11 and enlarge the opening degree of the bidirectional proportional valve 8, the proportion of the pressure of the brake master cylinder 11 to the brake cylinders is increased, the brake motor sensor group collects the rotating speed and torque signals of the brake motor and transmits the signals to the electronic control unit, the electronic control unit calculates the actual brake master cylinder pressure and compares the actual brake master cylinder pressure with the target brake master cylinder pressure to calculate the differential pressure, the motor controller 16 is further used for compensating the differential pressure, the wheel cylinder pressure sensor 7 collects the pressure of each brake cylinder and transmits the brake cylinder pressure signals to the electronic control unit 6, the electronic control unit 6 compares the actual brake cylinder pressure with the target brake cylinder pressure, the control of each two-way proportional valve 8 and the brake 9 effectively adjusts the single brake cylinder pressure.
As shown in fig. 1 to 5, the regular braking operation in step 2 is expressed by a braking motor rotation coefficient α calculated by the expression:
α＝lmaster cylinder/lPedal (1)
In the formula 1, lMaster cylinderMaximum stroke of piston rod of main cylinderPedalThe maximum stroke of the electronic brake pedal.
As shown in fig. 1 to 5, the reinforced collision distance time ETTC in step 2 is a determination condition, and the calculation expression thereof is:
in formula 2, Xrel、vrelAnd arelRespectively representing the relative distance, relative speed and relative acceleration of the vehicle relative to the front vehicle, Xb、vbAnd aaPosition, speed and acceleration of the preceding vehicle, Xa、vaAnd abThe position and the speed of the vehicle; if ETTC > TnWhen the vehicle is safe, the conventional braking is executed; if ETTC is less than or equal to TnIf so, judging the emergency level three; if Tb2≤ETTC≤Tb1If so, judging as an emergency level two; if ETTC is less than or equal to Tb2If so, judging as an emergency level one; definition of Tn、Tb1And Tb2The value is determined by the following formula:
the method adopts the time ETTC for strengthening the collision distance to judge, is suitable for various complex driving states, and sends different braking instructions according to different states, thereby realizing braking diversity, being more intelligent in braking and better in braking effect.
As shown in fig. 1-5, the pedal brake feedback simulator 3 generates a feedback force FfbThe computational expression of (a) is:
in equation 4, a is vehicle deceleration, M is vehicle mass, AmainThe master cylinder cross-sectional area, R tire radius, μbFactor of brake effectiveness, AwCross sectional area of wheel cylinder, rbThe effective radius of the brake is C, the comfort coefficient of the brake pedal is C, the pedal brake feedback simulator 3 is used for carrying out humanized intervention on a driver, misoperation of the driver is prevented, the feedback driver is timely given to carry out braking operation in time, a brake disc is generally arranged in the brake, the efficiency factor of the brake is the ratio of friction force obtained on the acting radius of the brake disc to input force, the comfort coefficient of the brake pedal is obtained by repeated tests when an automobile leaves a factory, and the C used for representing the comfort coefficient of the brake pedal is distinguished from a hydraulic pressure control module C for avoiding ambiguity.
As shown in FIGS. 1-5, the motor controller 16 is a PID closed-loop controller, and the braking motor sensor group collects the rotation speed and torque of the braking motor 14, which are obtained through a gain coefficient matrix K1Returning the data to the electronic control unit 6, and calculating the actual brake motor rotation coefficient alpha in the electronic control unit 6realAnd comparing the actual rotation coefficient with the target rotation coefficient of the brake motor to obtain the difference value between the actual rotation coefficient and the target rotation coefficient of the brake motor:
eα＝α-αreal×K1 (5)
the calculated difference is used as an input of the closed-loop control of the brake motor 14, and the output model is as follows:
in the formula 6, KpαIs a proportionality coefficient, TαIs a differential constant, u0αTo control constantThe rotating speed and the rotating speed of the brake motor 14 are controlled in a high-precision mode through the PID closed-loop controller, the braking force is more accurate, and the situation that excessive braking or insufficient braking force occurs is prevented.
As shown in FIGS. 1-5, the opening control of the two-way proportional valve 8 is controlled by a PID closed-loop controller, and the wheel cylinder pressure sensor 7 collects the pressure in the brake wheel cylinder through a gain coefficient matrix K2Returning the data to the electronic control unit 6, comparing the data with the target brake wheel cylinder pressure to obtain the difference value between the actual brake wheel cylinder pressure and the target brake wheel cylinder pressure:
ew＝P-Preal×K2 (7)
and taking the calculated difference value as the input of the closed-loop control of the opening 8 of the bidirectional proportional valve, wherein the output model is as follows:
in formula 8, LPIs a proportionality coefficient, TPIs a differential constant, v0PIn order to control the constant, the PID closed-loop controller gives full play to the proportional characteristic of the two-way proportional valve 8, the two-way proportional valve 8 is realized, and the control constant is introduced to improve the control precision, so that the opening degree of the two-way proportional valve 8 is accurately controlled, and the pressure of the brake wheel cylinder reaches an extremely high precision level.
As shown in fig. 1-5, in step 5, the output torque of the brake motor 14 is controlled by using a PID closed-loop controller, the output torque of the brake motor 14 is collected by a brake motor sensor group, the data is transmitted to the electronic control unit 6, the electronic control unit is compared with the target output torque, the PID closed-loop controller is used to perform closed-loop control on the output torque, the control logic and expression of the PID closed-loop controller are the same as those of the formulas 5 and 6, the control target is changed from the brake motor rotation coefficient to the brake motor output torque, and the brake motor output torque passes through a gain coefficient matrix K3Returning the data to the electronic control unit 6.
As shown in fig. 1-5, the gain coefficient matrix K1A matrix of gain coefficients K2A matrix of gain coefficients K3According to the coefficient of rotation of the braking motor respectivelyAnd the properties of the brake wheel cylinder pressure and the output torque are set and calculated through MATLAB software.
As shown in fig. 1-5, the motor controller 16 controls the brake motor 14 by controlling the pulse width modulation and the current direction of the input current of the brake motor 14, so as to increase the control accuracy and increase the transmission speed, and further, the brake motor 14 is selected as a permanent magnet ac servo motor.
The above examples are given for the purpose of illustrating the invention in a clear and non-limiting manner, and it will be apparent to those skilled in the art that many more modifications and variations can be made in the above-described embodiments without departing from the spirit and scope of the invention.
Claims (10)
1. An integrated electronic hydraulic brake system is characterized by comprising an electronic pedal module, a main cylinder pressure building module, a hydraulic control module and an electronic control unit;
the electronic pedal module comprises a brake pedal, an input push rod, a pedal sensor group and a pedal brake feedback simulator connected with the input push rod, wherein the sensor group outputs a pedal displacement signal and a pedal force signal;
the master cylinder pressure building module comprises a brake motor, a motor controller, a speed reducing mechanism and a brake motor sensor group, wherein the brake motor sensor group outputs a rotating speed signal and a torque signal of the brake motor;
the hydraulic pressure control module comprises a brake master cylinder, a piston push rod connected with the brake master cylinder, a brake wheel cylinder, a wheel cylinder pressure sensor, a brake, a liquid storage tank and a bidirectional proportional valve, wherein the liquid storage tank is connected with the brake master cylinder through an oil pipe;
the brake motor output shaft is connected with the input end of the speed reducing mechanism, the output end of the speed reducing mechanism is connected with the piston push rod, and the electronic control unit is respectively and electrically connected with the pedal sensor group, the pedal brake feedback simulator, the motor controller, the brake motor sensor group, the two-way proportional valve and the wheel cylinder pressure sensor.
2. The integrated electronic hydraulic brake system according to claim 1, wherein the pedal sensor group comprises a pedal displacement sensor and a pedal force sensor, the pedal displacement sensor and the pedal force sensor are arranged on the input push rod, the brake motor sensor group comprises a rotation speed sensor and a torque sensor, and the pedal displacement sensor, the pedal force sensor, the rotation speed sensor and the torque sensor are electrically connected with the electronic control unit.
3. The integrated electronic hydraulic brake system according to claim 1, wherein a first cavity and a second cavity are arranged in the brake master cylinder, the first cavity and the second cavity are respectively connected with the liquid storage tank through oil pipes, the brake wheel cylinder comprises a left front wheel cylinder, a left rear wheel cylinder, a right front wheel cylinder and a right rear wheel cylinder, the first cavity is communicated with the left rear wheel cylinder and the right rear wheel cylinder, the second cavity is communicated with the left front wheel cylinder and the right rear wheel cylinder, the left front wheel cylinder, the left rear wheel cylinder, the right front wheel cylinder and the right rear wheel cylinder are respectively connected with 1 brake through oil pipes, and each brake is correspondingly provided with 1 two-way proportional valve.
4. A control method of an integrated electro-hydraulic brake system according to any one of claims 1-3, characterized by comprising the steps of:
step 1: when a driver encounters an emergency situation during driving, a pedal displacement signal and a pedal force signal are input to an input push rod through an electronic brake pedal, a pedal sensor group collects the pedal displacement signal and the pedal force signal and transmits the pedal displacement signal and the pedal force signal to an electronic control unit, an upper layer controller is arranged on a vehicle, and the upper layer controller transmits a vehicle speed signal, a vehicle distance signal and an obstacle distance signal to the electronic control unit;
and 2, step: the method comprises the steps that an electronic control unit judges the braking intention of a driver according to received pedal displacement signals and pedal force signals, the electronic control unit generates a pedal braking feedback simulator control instruction according to the braking intention of the driver, the pedal braking feedback simulator generates corresponding pedal damping feeling according to the control instruction to feed back the braking behavior of the driver, the emergency level of vehicle braking is judged based on the enhanced distance collision time ETTC according to the received vehicle speed and the distance between the vehicle and an obstacle, if emergency braking is not needed, the conventional braking operation of the driver is not interfered, if emergency braking is needed, the emergency level is divided into three levels, namely an emergency level three, an emergency level two and an emergency level one, and the next step is carried out according to different emergency levels;
and step 3: if the emergency level is judged to be the third emergency level, the displacement of the brake motor in the unit stroke of the electronic brake pedal is changed, namely the rotation coefficient alpha of the brake motor is changed, so that the brake operation of a driver is assisted, and the aim of emergency braking is fulfilled; after receiving the instruction signal of the electronic control unit, the motor controller controls the brake motor to output torque and move to the speed reducing mechanism, and the speed reducing mechanism extrudes brake fluid in the brake master cylinder by driving the piston push rod to improve the brake pressure in the brake master cylinder, so that the pressure intensity is established for the brake master cylinder;
and 4, step 4: if the emergency level II is judged, the electronic control unit controls the two-way proportional valve to increase the opening degree and instantly increase the pressure of the brake wheel cylinder so as to achieve the aim of emergency braking; the wheel cylinder pressure sensor collects the pressure of each brake wheel cylinder and transmits a brake wheel cylinder pressure signal to the electronic control unit, and the electronic control unit compares the actual brake wheel cylinder pressure with the target brake wheel cylinder pressure and controls each two-way proportional valve to effectively adjust the pressure of each brake wheel cylinder;
and 5: if judging that the emergency level is first, the electronic control unit controls the brake motor to quickly increase the pressure of the brake master cylinder and simultaneously controls the two-way proportional valve to increase the opening degree, the electronic control unit simultaneously sends control signals to the motor controller and the two-way proportional valve to control the quick establishment of the pressure of the brake master cylinder and expand the opening degree of the two-way proportional valve to improve the proportion of the pressure of the brake master cylinder to the brake wheel cylinders, the brake motor sensor group collects the rotating speed and torque signals of the brake motor and transmits the signals to the electronic control unit, the electronic control unit calculates the pressure of the actual brake master cylinder and compares the pressure with the pressure of the target brake master cylinder to calculate the pressure difference, the motor controller further compensates the pressure difference, the wheel cylinder pressure sensor collects the pressure of each brake wheel cylinder and transmits the pressure signals of the brake wheel cylinders to the electronic control unit, and the electronic control unit compares the actual brake wheel cylinder pressure with the pressure of the target brake wheel cylinders, and controlling each two-way proportional valve to effectively regulate the pressure of a single brake wheel cylinder.
5. The control method of an integrated electronic hydraulic brake system according to claim 4, wherein the normal braking operation in step 2 is expressed by a braking motor rotation coefficient α, which is calculated by the following expression:
α＝lmaster cylinder/lPedal (1)
In the formula 1, lMaster cylinderMaximum stroke of piston rod of main cylinderPedalThe maximum stroke of the electronic brake pedal.
6. The control method of an integrated electronic hydraulic brake system according to claim 4, characterized in that the enhanced collision distance time ETTC in step 2 is a determination condition calculated by the expression:
in formula 2, Xrel、vrelAnd arelRespectively, relative distance, relative speed and relative acceleration of the vehicle relative to the preceding vehicle, Xb、vbAnd aaPosition, speed and acceleration of the preceding vehicle, Xa、vaAnd abPosition and speed of the vehicle; if ETTC > TnWhen the vehicle is safe, the conventional braking is executed; if ETTC is less than or equal to TnIf so, judging the emergency level three; if T isb2≤ETTC≤Tb1When the temperature of the water is higher than the set temperature,judging as an emergency level two; if ETTC is less than or equal to Tb2If so, judging as an emergency level one; definition of Tn、Tb1And Tb2The value is determined by the following formula:
7. the method of claim 4, wherein the pedal braking feedback simulator generates a feedback force FfbThe calculation expression of (a) is:
in equation 4, a is vehicle deceleration, M is vehicle mass, amainThe master cylinder cross-sectional area, R tire radius, μbFactor of brake effectiveness, AwCross sectional area of wheel cylinder, rbIs the effective radius of the brake, and C is the brake pedal comfort factor.
8. The method as claimed in claim 5, wherein the motor controller is a closed-loop controller, and the braking motor sensor group collects the rotation speed and torque of the braking motor through a gain coefficient matrix K1Returning data to the electronic control unit, and calculating the actual braking motor rotation coefficient alpha in the electronic control unitrealAnd comparing the actual rotation coefficient with the target rotation coefficient of the brake motor to obtain the difference value between the actual rotation coefficient and the target rotation coefficient of the brake motor:
eα＝α-αreal×K1 (5)
and taking the calculated difference value as the input of the closed-loop control of the brake motor, wherein the output model is as follows:
in the formula 6, KpαIs a proportionality coefficient, TαIs a differential constant, u0αAre control constants.
9. The method according to claim 4, wherein the opening of the two-way proportional valve 8 is controlled by a closed-loop controller, and the wheel cylinder pressure sensor collects the pressure in a wheel cylinder via a gain factor K2Returning data to the electronic control unit, and comparing the data with the target brake wheel cylinder pressure to obtain the pressure difference between the actual brake wheel cylinder pressure and the target brake wheel cylinder pressure:
ew＝P-Preal×K2 (7)
and taking the calculated pressure difference as the input of the opening closed-loop control of the bidirectional proportional valve, wherein the output model is as follows:
in formula 8, LPIs a proportionality coefficient, TPIs a differential constant, v0PAre control constants.
10. The method as claimed in claim 4, wherein the output torque of the brake motor in step 5 is controlled by a closed-loop controller, the output torque of the brake motor is collected by the sensor group of the brake motor, the data is transmitted to the electronic control unit, the output torque of the brake motor is closed-loop controlled by the closed-loop controller in comparison with the target output torque of the brake motor, the control logic and expression of the closed-loop controller are the same as those of the formula 5 and the formula 6, and the control target is changed from the rotation coefficient of the brake motor to the output torque of the brake motor.
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| JP2003063367A (en) * | 2001-08-22 | 2003-03-05 | Denso Corp | Dynamo electric brake device |
| US20180178773A1 (en) * | 2016-12-27 | 2018-06-28 | Robert Bosch Gmbh | Vehicle brake system and method of operating |
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| US20200148186A1 (en) * | 2019-08-16 | 2020-05-14 | Jilin University | Integrated Electric Booster braking system with Pedal Force Compensation Function |
| CN111409612A (en) * | 2020-04-10 | 2020-07-14 | 合肥工业大学 | Electronic hydraulic line control brake system and electronic hydraulic line control brake method thereof |
| CN114148303A (en) * | 2021-12-15 | 2022-03-08 | 安徽江淮汽车集团股份有限公司 | Electric brake power-assisted control method |
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- 2022-04-16 CN CN202210400404.4A patent/CN114771487A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003063367A (en) * | 2001-08-22 | 2003-03-05 | Denso Corp | Dynamo electric brake device |
| US20180178773A1 (en) * | 2016-12-27 | 2018-06-28 | Robert Bosch Gmbh | Vehicle brake system and method of operating |
| CN110065480A (en) * | 2019-05-23 | 2019-07-30 | 南京航空航天大学 | A kind of line traffic control electronic hydraulic brake system and control method based on accumulator compensation |
| US20200148186A1 (en) * | 2019-08-16 | 2020-05-14 | Jilin University | Integrated Electric Booster braking system with Pedal Force Compensation Function |
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