Method and system for retreating and supplementing liquid for electronic brake booster and automobile

Abstract

The invention discloses an electronic brake booster rollback fluid infusion method and system and an automobile, and the method comprises the steps that in the braking process, a pressure buildup unit is controlled to build brake pressure for a wheel end brake cylinder; acquiring a liquid quantity state of a brake system; the liquid quantity state of the braking system comprises the braking demand liquid quantity V1 needing to be consumed by a brake cylinder at the wheel end after braking during current driving, the maximum effective braking liquid quantity V2 capable of being provided by the braking system after braking during current driving and the total consumed liquid quantity V3 when the braking intention of a driver is reached after braking during current driving; determining whether the liquid quantity state of the brake system meets a liquid supplementing condition or not; and if yes, the pressure buildup unit is controlled to obtain the brake fluid from the brake fluid storage pot. According to the system, it can be ensured that enough liquid amount exists in the system to support pressure building, the situation that after the ABS function of a vehicle is activated, the brake liquid amount in the pressure building unit is not enough to continue to support the brake requirement of the next cycle is prevented, and the time of returning and liquid supplementing of the brake system can be accurately recognized.

Description

Technical Field

[0001] The invention relates to the technical field of automobile braking, and in particular to a method and system for retracting and replenishing fluid of an electronic brake booster, and an automobile. Background Art

[0002] As consumers' demands for automobile safety continue to increase, many electromechanical products have emerged in the field of automobile brake technology. Compared with traditional vacuum boosters, electronic brake boosters collect electrical signals from the push rod displacement sensor installed on the brake pedal, analyze the depth of the driver's brake pedal, and thus slow down the vehicle. However, in the actual development process, due to cost reasons, the choice of basic brakes (i.e. the size of the brakes) by various OEMs has become more and more extreme, which will lead to insufficient pressure-building fluid in the electronic brake booster system under certain extreme conditions, such as emergency braking to activate ABS conditions, ice and snow and other low adhesion conditions. If the brake fluid is not replenished in time at this time, the vehicle's response will not meet the driver's intention to slow down.

[0003] CN118457532A discloses a method and device for determining the amount of fluid to be returned during vehicle braking. The method at least includes: determining the driving distance corresponding to the vehicle consuming all the brake fluid during the vehicle deceleration process; determining the current speed and current deceleration of the vehicle when the anti-lock braking system ABS of the vehicle is triggered; calculating the braking distance required for the vehicle to stop from the current speed according to the current deceleration; determining the total amount of brake fluid in the vehicle, and calculating the amount of fluid to be returned required by the vehicle according to the total amount of brake fluid, the driving distance and the braking distance. This solution can determine the amount of brake fluid to be returned according to the actual driving conditions of the vehicle during the braking process, thereby avoiding the process of returning too much brake fluid for a long time, shortening the braking time of the vehicle and improving the braking efficiency. Undoubtedly, the technical solution disclosed in the above patent document is a beneficial attempt in the relevant technical field. However, there are still the following shortcomings: it is impossible to accurately identify the timing of the brake system to return the fluid. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide an electronic brake booster back-off and fluid replenishment method, system and vehicle, which can ensure that there is sufficient fluid in the system to support pressure building, prevent the situation where the brake fluid in the pressure building unit of the vehicle is insufficient to continue to support the braking requirements of the next cycle after the ABS function is activated, and can accurately identify the timing of the brake system back-off and fluid replenishment.

[0005] A method for reversing and replenishing fluid of an electronic brake booster in the present invention comprises:

[0006] During braking, the pressure building unit is controlled to build up braking pressure to the wheel end brake cylinder;

[0007] Obtain the brake system fluid state; the brake system fluid state includes: the brake demand fluid volume V1 that needs to be consumed by the wheel end brake cylinder after braking during the current driving, the maximum effective brake fluid volume V2 that the brake system can provide after braking during the current driving, and the total fluid consumption V3 when the driver's braking intention is achieved after braking during the current driving;

[0008] Determine whether the brake system fluid quantity state satisfies the fluid replenishment condition; if so, control the pressure building unit to obtain brake fluid from the brake fluid reservoir.

[0009] Further, if it is determined that the brake system fluid quantity state does not satisfy the fluid replenishment condition, the pressure building unit is not controlled to obtain brake fluid from the brake fluid reservoir.

[0010] Further, the determining whether the brake system fluid level state satisfies the fluid replenishment condition includes:

[0011] The fluid loss index V is calculated based on the brake demand fluid volume V1, the maximum effective brake fluid volume V2, and the total consumed fluid volume V3. index ;

[0012] Determine the liquid loss index V index Is it greater than a preset threshold; if greater than, it is determined that the real-time state of the electronic brake booster meets the fluid replenishment condition; if not greater than, it is determined that the real-time state of the electronic brake booster does not meet the fluid replenishment condition.

[0013] Furthermore, the liquid loss index V index The calculation method is

[0014] Furthermore, the calculation method of the brake fluid demand V1 is: V1 = V 1_FL +V 1_FR +V 1_RL +V 1_RR +V 1_com ;

[0015] Among them, V 1_FL The pressure value is calculated according to the software pressure calculation model, and then the PV characteristic curve of the left front wheel is queried to obtain V 1_FR The pressure value is calculated according to the software pressure calculation model, and then the PV characteristic curve of the right front wheel is queried to obtain V 1_RL The pressure value is calculated according to the software pressure calculation model, and then the PV characteristic curve of the left rear wheel is queried to obtain V 1_RR It is obtained by querying the PV characteristic curve of the right rear wheel after calculating the pressure value according to the software pressure calculation model. V1_com is the compensation value obtained through calibration.

[0016] Furthermore, the pressure-building piston of the pressure-building unit is driven by a motor; the maximum effective brake fluid volume V2 is calculated as follows: V2 = π × D 2 ×n×z×p×T2; When the ABS function is activated, the total fluid consumption V3 is calculated as follows: V3=V1+π×D 2 ×n×z×p×T3; when the ABS function is not activated, the total fluid consumption V3 is 0;

[0017] Among them, π is the pi, D is the diameter of the pressure building piston of the pressure building unit, n is the rotation speed of the motor, z is the number of threads of the ball screw of the pressure building unit, p is the pitch of the ball screw of the pressure building unit, T2 is the time that the motor has run during the braking process, and T3 is the sum of the ABS pressure relief time.

[0018] Furthermore, during the braking process, controlling the pressure building unit to build up braking pressure to the wheel end brake cylinder includes:

[0019] Normal braking: the brake fluid channel between the brake fluid reservoir and the pressure building unit is isolated, and the brake fluid channel between the pressure building unit and the wheel-end brake cylinder is connected; when ABS pressure relief is performed, the brake fluid channel between the wheel-end brake cylinder and the brake fluid reservoir is connected; when ABS pressure relief is not performed, the brake fluid channel between the wheel-end brake cylinder and the brake fluid reservoir is isolated; the motor rotates forward and drives the pressure building piston of the pressure building unit at a first speed in a direction away from the initial position.

[0020] Further, controlling the pressure building unit to obtain brake fluid from the brake fluid reservoir comprises:

[0021] Preparation for fluid replenishment; isolating the brake fluid channel between the pressure building unit and the wheel-end brake cylinder, and isolating the brake fluid channel between the wheel-end brake cylinder and the brake fluid reservoir; the motor gradually changes from forward rotation in normal braking to reverse rotation, and drives the pressure building piston of the pressure building unit to retreat toward the initial position at the second speed, so that the internal pressure of the pressure building unit gradually decreases until the pressure is 0;

[0022] Perform fluid replenishment; open the brake fluid channel between the brake fluid reservoir and the pressure building unit; the motor continues to reverse at the second speed to drive the pressure building piston of the pressure building unit to continue to retreat toward the initial position, and the brake fluid flows from the brake fluid reservoir into the interior of the pressure building unit under the action of negative pressure;

[0023] Transition stage; the brake fluid channel between the brake fluid reservoir and the pressure building unit is isolated; the reverse rotation of the motor gradually changes to forward rotation, and drives the pressure building piston of the pressure building unit to move forward in a direction away from the initial position at a third speed, and the third speed is greater than the first speed, until the internal pressure of the pressure building unit increases to a level not less than the pressure before the fluid replenishment preparation;

[0024] The fluid replenishment is completed; the brake fluid channel between the brake fluid reservoir and the pressure building unit is isolated, and the brake fluid channel between the pressure building unit and the wheel-end brake cylinder is connected. When ABS pressure relief is performed, the brake fluid channel between the wheel-end brake cylinder and the brake fluid reservoir is connected, and when ABS pressure relief is not performed, the brake fluid channel between the wheel-end brake cylinder and the brake fluid reservoir is isolated; the motor gradually reduces the first speed from the forward rotation at the third speed.

[0025] An electronic brake booster retraction and fluid replenishment system in the present invention comprises a brake fluid reservoir, a pressure building unit, a motor, a wheel end brake cylinder, a controller and eleven solenoid valves;

[0026] There are brake fluid channels between the brake fluid reservoir and the pressure building unit, between the pressure building unit and the wheel-end brake cylinder, and between the wheel-end brake cylinder and the brake fluid reservoir;

[0027] There are four wheel-end brake cylinders, which are respectively arranged on the left front wheel, the right rear wheel, the right front wheel and the left rear wheel;

[0028] A solenoid valve four is provided between the pressure-building unit and the left front wheel, and a solenoid valve eight is provided between the left front wheel and the brake fluid reservoir; a solenoid valve five is provided between the pressure-building unit and the right rear wheel, and a solenoid valve nine is provided between the right rear wheel and the brake fluid reservoir; a solenoid valve six is ​​provided between the pressure-building unit and the right front wheel, and a solenoid valve ten is provided between the right front wheel and the brake fluid reservoir; a solenoid valve seven is provided between the pressure-building unit and the left rear wheel, and a solenoid valve eleven is provided between the left rear wheel and the brake fluid reservoir;

[0029] A solenoid valve 2 is provided between the side of the solenoid valve 4 and the solenoid valve 5 away from the wheel-end brake cylinder and the pressure building unit, and a solenoid valve 3 is provided between the side of the solenoid valve 6 and the solenoid valve 7 away from the wheel-end brake cylinder and the pressure building unit;

[0030] The controller is used to control the on and off of eleven solenoid valves and the operation of the motor to achieve:

[0031] During braking, the pressure building unit is controlled to build up braking pressure to the wheel end brake cylinder;

[0032] Obtain the brake system fluid state; the brake system fluid state includes: the brake demand fluid volume V1 that needs to be consumed by the wheel end brake cylinder after braking during the current driving, the maximum effective brake fluid volume V2 that the brake system can provide after braking during the current driving, and the total fluid consumption V3 when the driver's braking intention is achieved after braking during the current driving;

[0033] Determine whether the brake system fluid quantity state satisfies the fluid replenishment condition; if so, control the pressure building unit to obtain brake fluid from the brake fluid reservoir.

[0034] An automobile in the present invention uses the above-mentioned electronic brake booster reversal and fluid replenishment method or the above-mentioned electronic brake booster reversal and fluid replenishment system.

[0035] The beneficial effects of the present invention are:

[0036] (1) When the fluid level in the brake system meets the fluid replenishment condition, the present invention controls the pressure building unit to obtain brake fluid from the brake fluid reservoir to ensure that there is sufficient fluid in the system to support pressure building, thereby preventing the situation where the brake fluid in the pressure building unit is insufficient to continue to support the braking demand of the next cycle after the ABS function of the vehicle is activated.

[0037] (2) The present invention can accurately identify the timing of brake system reversal and fluid replenishment.

[0038] (3) The present invention designs identification strategies and full-process control procedures for normal braking, fluid replenishment preparation, fluid replenishment execution, transition phase, and fluid replenishment completion, which can ensure timely response and handling of control. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0040] Figure 1 It is a schematic diagram of the process of the present invention;

[0041] Figure 2 A schematic diagram of the brake fluid flow path of the present invention;

[0042] Figure 3 is a schematic diagram of the fluid volume state of the brake system of the present invention;

[0043] Figure 4 It is a schematic diagram of the motor speed of the present invention. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0045] like Figure 1 As shown, a method for reversing and replenishing fluid of an electronic brake booster in this embodiment includes:

[0046] During braking, the pressure building unit is controlled to build up braking pressure to the wheel end brake cylinder;

[0047] Get the brake system fluid status; such as Figure 2 As shown, the brake system fluid state includes: the brake demand fluid volume V1 that the wheel end brake cylinder needs to consume after braking during the current driving, the maximum effective brake fluid volume V2 that the brake system can provide after braking during the current driving, and the total fluid consumption V3 when the driver's braking intention is achieved after braking during the current driving;

[0048] Determine whether the brake system fluid quantity state satisfies the fluid replenishment condition; if so, control the pressure building unit to obtain brake fluid from the brake fluid reservoir.

[0049] After the ABS (anti-lock braking system) function of the vehicle is activated, the decoupled electronic brake booster needs to release a portion of the brake fluid into the brake oil reservoir through the internal pressure relief valve. Since the decoupled electronic brake booster relies on the motor to act on the pressure building unit to build up the brake pressure, and the amount of brake fluid that the pressure building unit can provide is certain, after the ABS activates the hydraulic pressure, the amount of brake fluid in the pressure building unit will be insufficient to continue to support the driver's braking needs for the next cycle. In order to solve this technical problem, after obtaining the brake system fluid state, this embodiment determines whether the brake system fluid state meets the fluid replenishment condition; and when the brake system fluid state meets the fluid replenishment condition, the pressure building unit is controlled to obtain brake fluid from the brake fluid reservoir.

[0050] like Figure 2 As shown, there are brake fluid channels between the brake fluid reservoir and the pressure building unit, between the pressure building unit and the wheel-end brake cylinder, and between the wheel-end brake cylinder and the brake fluid reservoir; there are four wheel-end brake cylinders, which are respectively arranged on the left front wheel, the right rear wheel, the right front wheel and the left rear wheel; a solenoid valve four is arranged between the pressure building unit and the left front wheel, a solenoid valve eight is arranged between the left front wheel and the brake fluid reservoir; a solenoid valve five is arranged between the pressure building unit and the right rear wheel, and a solenoid valve eight is arranged between the right rear wheel and the brake fluid reservoir Solenoid valve nine; solenoid valve six is ​​arranged between the pressure building unit and the right front wheel, and solenoid valve ten is arranged between the right front wheel and the brake fluid reservoir; solenoid valve seven is arranged between the pressure building unit and the left rear wheel, and solenoid valve eleven is arranged between the left rear wheel and the brake fluid reservoir; solenoid valve two is arranged between the solenoid valve four and the side of the solenoid valve five away from the wheel-end brake cylinder and the pressure building unit, and solenoid valve three is arranged between the solenoid valve six and the side of the solenoid valve seven away from the wheel-end brake cylinder and the pressure building unit.

[0051] The function of solenoid valve 1 is to ensure that the brake fluid can only flow from the brake fluid reservoir to the pressure building unit. When the driver has a braking demand, solenoid valves 2, 3, 4, 5, 6 and 7 are in the open state, and solenoid valves 8, 9, 10 and 11 are in the closed state. At this time, the motor will push the pressure building unit to build up braking pressure on the four wheels to meet the driver's braking needs. When the ABS (anti-lock braking) function is activated, the electronic brake booster will control solenoid valves 8, 9, 10 and 11 to be in the open state during pressure relief, so that the brake fluid in the entire system flows along the brake fluid. Figure 2 The fluid leaks back into the brake oil tank in the direction indicated by the middle arrow. At this time, the motor has been pushing the pressure building unit to build up hydraulic pressure. Due to the size limitation of the pressure building unit structure, there will be no excess brake fluid in the system to support the pressure building. At this time, the electronic brake booster will control the motor to retract, open solenoid valve one, close solenoid valves two and three, and allow the brake fluid reservoir to replenish the pressure building unit, thereby ensuring that there is enough fluid in the system to support the pressure building.

[0052] In this embodiment, if it is determined that the brake system fluid quantity state does not satisfy the fluid replenishment condition, the pressure building unit is not controlled to obtain brake fluid from the brake fluid reservoir.

[0053] In this embodiment, determining whether the brake system fluid level state satisfies the fluid replenishment condition includes:

[0054] The fluid loss index V is calculated based on the brake demand fluid volume V1, the maximum effective brake fluid volume V2, and the total consumed fluid volume V3. index ;

[0055] Determine the liquid loss index V index Is it greater than a preset threshold; if greater than, it is determined that the real-time state of the electronic brake booster meets the fluid replenishment condition; if not greater than, it is determined that the real-time state of the electronic brake booster does not meet the fluid replenishment condition.

[0056] In this embodiment, the liquid loss index V index The calculation method is V index The effective value of the calculated value is 0-1. If V index If the calculated value is not 0-1, the calculated value is considered invalid and recalculated. The preset threshold is determined according to the parameters of the pressure building unit and the motor, for example, it can be 0.5, 0.7, 0.85, etc. index By comparing with the preset threshold, it can accurately identify the timing for the brake system to roll back and replenish fluid.

[0057] In this embodiment, the calculation method of the brake fluid demand V1 is: V1 = V 1_FL +V 1_FR +V 1_RL +V1_RR +V 1_com ;

[0058] Among them, V 1_FL The pressure value is calculated according to the software pressure calculation model, and then the PV characteristic curve of the left front wheel is queried to obtain V 1_FR The pressure value is calculated according to the software pressure calculation model, and then the PV characteristic curve of the right front wheel is queried to obtain V 1_RL The pressure value is calculated according to the software pressure calculation model, and then the PV characteristic curve of the left rear wheel is queried to obtain V 1_RR It is obtained by querying the PV characteristic curve of the right rear wheel after calculating the pressure value according to the software pressure calculation model. V1_com is the compensation value obtained through calibration.

[0059] The software pressure calculation model belongs to the existing technology and is pre-stored in the controller. The pressure value is calculated by comprehensively considering information such as the stroke of the electronic brake pedal, the specifications of the hydraulic cylinders of each wheel, and the vehicle's own weight; the PV characteristic curve, that is, the pressure-fluid volume characteristic curve, is obtained through experiments and pre-stored in the controller.

[0060] In this embodiment, the pressure-building piston of the pressure-building unit is driven by a motor; the maximum effective brake fluid volume V2 is calculated as follows: V2 = π × D 2 ×n×z×p×T2; When the ABS function is activated, the total fluid consumption V3 is calculated as follows: V3=V1+π×D 2 ×n×z×p×T3; when the ABS function is not activated, the total fluid consumption V3 is 0;

[0061] Among them, π is the pi, D is the diameter of the pressure building piston of the pressure building unit, n is the rotation speed of the motor, z is the number of threads of the ball screw of the pressure building unit, p is the pitch of the ball screw of the pressure building unit, T2 is the time that the motor has run during the braking process, and T3 is the sum of the ABS pressure relief time.

[0062] like Figure 4 As shown, in this embodiment, during the braking process, controlling the pressure building unit to build up braking pressure to the wheel end brake cylinder includes:

[0063] Normal braking: the brake fluid channel between the brake fluid reservoir and the pressure building unit is isolated, and the brake fluid channel between the pressure building unit and the wheel-end brake cylinder is connected; when ABS pressure relief is performed, the brake fluid channel between the wheel-end brake cylinder and the brake fluid reservoir is connected; when ABS pressure relief is not performed, the brake fluid channel between the wheel-end brake cylinder and the brake fluid reservoir is isolated; the motor rotates forward and drives the pressure building piston of the pressure building unit at a first speed in a direction away from the initial position.

[0064] like Figure 4As shown, in this embodiment, controlling the pressure building unit to obtain brake fluid from the brake fluid reservoir includes:

[0065] Preparation for fluid replenishment; isolating the brake fluid channel between the pressure building unit and the wheel-end brake cylinder, and isolating the brake fluid channel between the wheel-end brake cylinder and the brake fluid reservoir; the motor gradually changes from forward rotation in normal braking to reverse rotation, and drives the pressure building piston of the pressure building unit to retreat toward the initial position at the second speed, so that the internal pressure of the pressure building unit gradually decreases until the pressure is 0;

[0066] Perform fluid replenishment; open the brake fluid channel between the brake fluid reservoir and the pressure building unit; the motor continues to reverse at the second speed to drive the pressure building piston of the pressure building unit to continue to retreat toward the initial position, and the brake fluid flows from the brake fluid reservoir into the interior of the pressure building unit under the action of negative pressure;

[0067] Transition stage; the brake fluid channel between the brake fluid reservoir and the pressure building unit is isolated; the reverse rotation of the motor gradually changes to forward rotation, and drives the pressure building piston of the pressure building unit to move forward in a direction away from the initial position at a third speed, and the third speed is greater than the first speed, until the internal pressure of the pressure building unit increases to a level not less than the pressure before the fluid replenishment preparation;

[0068] The fluid replenishment is completed; the brake fluid channel between the brake fluid reservoir and the pressure building unit is isolated, and the brake fluid channel between the pressure building unit and the wheel-end brake cylinder is connected. When ABS pressure relief is performed, the brake fluid channel between the wheel-end brake cylinder and the brake fluid reservoir is connected, and when ABS pressure relief is not performed, the brake fluid channel between the wheel-end brake cylinder and the brake fluid reservoir is isolated; the motor gradually reduces the first speed from the forward rotation at the third speed.

[0069] The recognition strategies and the whole process control process of normal braking, fluid filling preparation, fluid filling execution, transition phase and fluid filling end are designed to ensure timely response and response of control. In addition, the third speed is greater than the first speed, which can quickly build pressure, so that the internal pressure of the pressure building unit is quickly increased to a pressure not less than the pressure before fluid filling preparation.

[0070] like Figure 2 As shown, an electronic brake booster retraction and fluid replenishment system in this embodiment includes a brake fluid reservoir, a pressure building unit, a motor, a wheel-end brake cylinder, a controller, and eleven solenoid valves;

[0071] There are brake fluid channels between the brake fluid reservoir and the pressure building unit, between the pressure building unit and the wheel-end brake cylinder, and between the wheel-end brake cylinder and the brake fluid reservoir;

[0072] There are four wheel-end brake cylinders, which are respectively arranged on the left front wheel, the right rear wheel, the right front wheel and the left rear wheel;

[0073] A solenoid valve four is provided between the pressure-building unit and the left front wheel, and a solenoid valve eight is provided between the left front wheel and the brake fluid reservoir; a solenoid valve five is provided between the pressure-building unit and the right rear wheel, and a solenoid valve nine is provided between the right rear wheel and the brake fluid reservoir; a solenoid valve six is ​​provided between the pressure-building unit and the right front wheel, and a solenoid valve ten is provided between the right front wheel and the brake fluid reservoir; a solenoid valve seven is provided between the pressure-building unit and the left rear wheel, and a solenoid valve eleven is provided between the left rear wheel and the brake fluid reservoir;

[0074] A solenoid valve 2 is provided between the side of the solenoid valve 4 and the solenoid valve 5 away from the wheel-end brake cylinder and the pressure building unit, and a solenoid valve 3 is provided between the side of the solenoid valve 6 and the solenoid valve 7 away from the wheel-end brake cylinder and the pressure building unit;

[0075] The controller is used to control the on and off of eleven solenoid valves and the operation of the motor to achieve:

[0076] During braking, the pressure building unit is controlled to build up braking pressure to the wheel end brake cylinder;

[0077] Obtain the brake system fluid state; the brake system fluid state includes: the brake demand fluid volume V1 that needs to be consumed by the wheel end brake cylinder after braking during the current driving, the maximum effective brake fluid volume V2 that the brake system can provide after braking during the current driving, and the total fluid consumption V3 when the driver's braking intention is achieved after braking during the current driving;

[0078] Determine whether the brake system fluid quantity state satisfies the fluid replenishment condition; if so, control the pressure building unit to obtain brake fluid from the brake fluid reservoir.

[0079] A car in this embodiment uses the above-mentioned electronic brake booster return and fluid replenishment method or the above-mentioned electronic brake booster return and fluid replenishment system.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for reversing and replenishing fluid for an electronic brake booster, characterized in that: include: During braking, the pressure building unit is controlled to build up braking pressure to the wheel end brake cylinder; Get the brake system fluid status; The brake system fluid volume state includes: the brake demand fluid volume V1 that needs to be consumed by the wheel end brake cylinder after braking during the current driving, the maximum effective brake fluid volume V2 that the brake system can provide after braking during the current driving, and the total fluid consumption V3 when the driver's braking intention is achieved after braking during the current driving; Determine whether the brake system fluid quantity state satisfies the fluid replenishment condition; if so, control the pressure building unit to obtain brake fluid from the brake fluid reservoir.

2. The method for reversing and replenishing fluid of an electronic brake booster according to claim 1, characterized in that: If it is determined that the brake system fluid quantity state does not satisfy the fluid replenishment condition, the pressure building unit is not controlled to obtain brake fluid from the brake fluid reservoir.

3. The method for reversing and replenishing fluid of an electronic brake booster according to claim 1 or 2, characterized in that: The determining whether the brake system fluid quantity state satisfies the fluid replenishment condition comprises: The fluid loss index V is calculated based on the brake demand fluid volume V1, the maximum effective brake fluid volume V2, and the total consumed fluid volume V3. index ; Determine the liquid loss index V index Is it greater than a preset threshold; if greater than, it is determined that the real-time state of the electronic brake booster meets the fluid replenishment condition; if not greater than, it is determined that the real-time state of the electronic brake booster does not meet the fluid replenishment condition.

4. The method for reversing and replenishing fluid of an electronic brake booster according to claim 3, characterized in that: The fluid loss index V index The calculation method is 5. The method for reversing and replenishing fluid of an electronic brake booster according to claim 1 or 2, characterized in that: The calculation method of the brake fluid demand V1 is: V1 = V 1_FL +V 1_FR +V 1_RL +V 1_RR +V 1_com ; Among them, V 1_FL The pressure value is calculated according to the software pressure calculation model, and then the PV characteristic curve of the left front wheel is queried to obtain V 1_FR The pressure value is calculated according to the software pressure calculation model, and then the PV characteristic curve of the right front wheel is queried to obtain V 1_RL The pressure value is calculated according to the software pressure calculation model, and then the PV characteristic curve of the left rear wheel is queried to obtain V 1_RR It is obtained by querying the PV characteristic curve of the right rear wheel after calculating the pressure value according to the software pressure calculation model. V1_com is the compensation value obtained through calibration.

6. The method for reversing and replenishing fluid for an electronic brake booster according to claim 1 or 2, characterized in that: The pressure-building piston of the pressure-building unit is driven by a motor; the maximum effective brake fluid volume V2 is calculated as follows: V2 = π × D 2 ×n×z×p×T2; When the ABS function is activated, the total fluid consumption V3 is calculated as follows: V3=V1+π×D 2 ×n×z×p×T3; when the ABS function is not activated, the total fluid consumption V3 is 0; Among them, π is the pi, D is the diameter of the pressure building piston of the pressure building unit, n is the rotation speed of the motor, z is the number of threads of the ball screw of the pressure building unit, p is the pitch of the ball screw of the pressure building unit, T2 is the time that the motor has run during the braking process, and T3 is the sum of the ABS pressure relief time.

7. The method for reversing and replenishing fluid of an electronic brake booster according to claim 1, characterized in that: During the braking process, controlling the pressure building unit to build up braking pressure on the wheel end brake cylinder includes: Normal braking: the brake fluid channel between the brake fluid reservoir and the pressure building unit is isolated, and the brake fluid channel between the pressure building unit and the wheel-end brake cylinder is connected; when ABS pressure relief is performed, the brake fluid channel between the wheel-end brake cylinder and the brake fluid reservoir is connected; when ABS pressure relief is not performed, the brake fluid channel between the wheel-end brake cylinder and the brake fluid reservoir is isolated; the motor rotates forward and drives the pressure building piston of the pressure building unit at a first speed in a direction away from the initial position.

8. The method for reversing and replenishing fluid of an electronic brake booster according to claim 7, characterized in that: The controlling the pressure building unit to obtain brake fluid from the brake fluid reservoir comprises: Preparation for fluid replenishment; isolating the brake fluid channel between the pressure building unit and the wheel-end brake cylinder, and isolating the brake fluid channel between the wheel-end brake cylinder and the brake fluid reservoir; the motor gradually changes from forward rotation in normal braking to reverse rotation, and drives the pressure building piston of the pressure building unit to retreat toward the initial position at the second speed, so that the internal pressure of the pressure building unit gradually decreases until the pressure is 0; Perform fluid replenishment; open the brake fluid channel between the brake fluid reservoir and the pressure building unit; the motor continues to reverse at the second speed to drive the pressure building piston of the pressure building unit to continue to retreat toward the initial position, and the brake fluid flows from the brake fluid reservoir into the interior of the pressure building unit under the action of negative pressure; Transition stage; the brake fluid channel between the brake fluid reservoir and the pressure building unit is isolated; the reverse rotation of the motor gradually changes to forward rotation, and drives the pressure building piston of the pressure building unit to move forward in a direction away from the initial position at a third speed, and the third speed is greater than the first speed, until the internal pressure of the pressure building unit increases to a level not less than the pressure before the fluid replenishment preparation; The fluid replenishment is completed; the brake fluid channel between the brake fluid reservoir and the pressure building unit is isolated, and the brake fluid channel between the pressure building unit and the wheel-end brake cylinder is connected. When ABS pressure relief is performed, the brake fluid channel between the wheel-end brake cylinder and the brake fluid reservoir is connected, and when ABS pressure relief is not performed, the brake fluid channel between the wheel-end brake cylinder and the brake fluid reservoir is isolated; the motor gradually reduces the first speed from the forward rotation at the third speed.

9. An electronic brake booster retraction and fluid replenishment system, characterized in that: It includes a brake fluid reservoir, a pressure building unit, a motor, a wheel-end brake cylinder, a controller, and eleven solenoid valves; There are brake fluid channels between the brake fluid reservoir and the pressure building unit, between the pressure building unit and the wheel-end brake cylinder, and between the wheel-end brake cylinder and the brake fluid reservoir; There are four wheel-end brake cylinders, which are respectively arranged on the left front wheel, the right rear wheel, the right front wheel and the left rear wheel; A solenoid valve four is provided between the pressure-building unit and the left front wheel, and a solenoid valve eight is provided between the left front wheel and the brake fluid reservoir; a solenoid valve five is provided between the pressure-building unit and the right rear wheel, and a solenoid valve nine is provided between the right rear wheel and the brake fluid reservoir; a solenoid valve six is ​​provided between the pressure-building unit and the right front wheel, and a solenoid valve ten is provided between the right front wheel and the brake fluid reservoir; a solenoid valve seven is provided between the pressure-building unit and the left rear wheel, and a solenoid valve eleven is provided between the left rear wheel and the brake fluid reservoir; A solenoid valve 2 is provided between the side of the solenoid valve 4 and the solenoid valve 5 away from the wheel-end brake cylinder and the pressure building unit, and a solenoid valve 3 is provided between the side of the solenoid valve 6 and the solenoid valve 7 away from the wheel-end brake cylinder and the pressure building unit; The controller is used to control the on and off of eleven solenoid valves and the operation of the motor to achieve: During braking, the pressure building unit is controlled to build up braking pressure to the wheel end brake cylinder; Obtain the brake system fluid state; the brake system fluid state includes: the brake demand fluid volume V1 that needs to be consumed by the wheel end brake cylinder after braking during the current driving, the maximum effective brake fluid volume V2 that the brake system can provide after braking during the current driving, and the total fluid consumption V3 when the driver's braking intention is achieved after braking during the current driving; Determine whether the brake system fluid quantity state satisfies the fluid replenishment condition; if so, control the pressure building unit to obtain brake fluid from the brake fluid reservoir.

10. An automobile, characterized in that: The electronic brake booster reversal and fluid replenishment method as described in any one of claims 1 to 8 or the electronic brake booster reversal and fluid replenishment system as described in claim 9 is used.

Images