CN-121973748-A - Method and system for diagnosing faults of boosting pressure building loop of brake control system

CN121973748ACN 121973748 ACN121973748 ACN 121973748ACN-121973748-A

Abstract

The invention discloses a method and a system for diagnosing faults of a booster pressure building loop of a brake control system, wherein the diagnosis method comprises the steps of obtaining parameters of a brake working condition; the diagnosis system comprises a liquid storage pot, a first isolation valve, a simulation master cylinder, a first pressure sensor, a second isolation valve, a third isolation valve and a pedal simulator, a simulation master cylinder loop, and a power-assisted pressure building loop, wherein the simulation master cylinder loop is formed by the liquid storage pot, the first isolation valve, the simulation master cylinder, the first pressure sensor, the second isolation valve, the third isolation valve and the pedal simulator, and the power-assisted pressure building loop is formed by the liquid inlet valve, the liquid outlet valve, the fourth isolation valve, the pressure building master cylinder, the liquid supplementing valve and the second pressure sensor. The invention can avoid the problem of power assisting performance reduction when the whole vehicle cannot assist or mechanical backup occurs when the liquid replenishing valve is opened and the liquid storage pot lacks brake liquid, and effectively ensures the driving safety of a driver.

Inventors

CHEN JINGJIE
SHI DEYU
HUANG PINGYU
YU YANFU

Assignees

浙江千顾汽车科技有限公司
千顾汽车科技(江苏)有限公司
千顾科技(上海)有限公司

Dates

Publication Date: 20260505
Application Date: 20260209

Claims (10)

1. A power-assisted pressure-build loop fault diagnosis method of a brake control system is characterized by comprising the following steps: acquiring a braking working condition parameter; judging and executing a self-checking liquid draining process to drain brake liquid based on the acquired brake working condition parameters; Executing a self-checking pressure building process and a self-checking back suction process to actively manufacture back suction working conditions, acquiring and evaluating air content, and judging the working state of the power-assisted pressure building loop.
2. The method for diagnosing a brake control system as recited in claim 1, wherein the step of determining and executing a self-test drainage process to drain the brake fluid based on the obtained brake condition parameters includes: when the brake pedal is not stepped and the wheel rotating speed exceeds a set threshold value, actively opening a fourth isolation valve and closing a liquid inlet valve; The pressure-build master cylinder is driven to advance so that brake fluid flows through the fourth isolation valve, the second isolation valve, the simulation master cylinder and the first isolation valve into the reservoir.
3. The method for diagnosing a brake control system for assisting a vehicle in accordance with claim 1, wherein said executing a self-checking pressure build-up process and a self-checking suck-back process to actively create a suck-back condition comprises: actively closing a fourth isolation valve to drive the pressure building master cylinder to compress; When the second pressure sensor detects that the internal pressure of the pressure building master cylinder reaches a first pressure threshold value P1, a corresponding first stroke value S1 is recorded, and a corresponding first Air content value Air1 is estimated; actively closing the fourth isolation valve, driving the pressure-building master cylinder to retract to a preset suction stroke, and then compressing again; When the second pressure sensor detects that the internal pressure of the pressure building master cylinder reaches the first pressure threshold value P1, a corresponding second stroke value S2 is recorded, and a corresponding second Air content value Air2 is evaluated.
4. The method for diagnosing a failure in a booster pressure build-up circuit of a brake control system according to claim 3, wherein said first Air content value Air1 and said second Air content value Air2 are calculated according to the following formulas: Air=(Volume1-Volume2)*α the Volume1 is the liquid amount consumed when the pressure building master cylinder is at rest to build pressure P1, the Volume2 is the theoretical liquid amount corresponding to the pressure building master cylinder build pressure to build pressure P1, the theoretical liquid amount is obtained by looking up a table of theoretical process variables of a pressure building master cylinder cavity of the product, and alpha is an air coefficient.
5. The method for diagnosing a failure of a booster boost circuit of a brake control system according to claim 1, wherein said judging the operating state of the booster boost circuit includes: when the pressure cannot be built to the first pressure threshold P1 in the process of advancing the compression again after the pressure-built main cylinder retreats to suck the preset stroke, the liquid supplementing valve is judged to be opened and cannot be closed, the power-assisted braking function is closed, and the mechanical backup is degraded.
6. The method for diagnosing a failure of a booster circuit in a brake control system as defined in claim 5, wherein said determining an operating state of the booster circuit further comprises: When the difference value between the second stroke value S2 and the first stroke value S1 is smaller than the first stroke threshold value Smin, judging that the fluid infusion valve cannot be closed after being opened, sending out a fault alarm signal, and simultaneously closing an anti-lock braking function; When the difference value between the second Air content value Air2 and the first Air content value Air1 is larger than the Air content upper limit A0, judging that no brake fluid exists in the liquid storage pot and a back suction body exists, closing a booster braking function and degrading mechanical backup.
7. A power-assisted pressure-build-up circuit failure diagnosis system of a brake control system, characterized in that the diagnosis system is for operating the power-assisted pressure-build-up circuit failure diagnosis method of a brake control system according to any one of claims 1 to 6, the diagnosis system comprising: A liquid storage pot, a first isolation valve, a simulation main cylinder, a first pressure sensor a simulated master cylinder loop consisting of a second isolation valve, a third isolation valve and a pedal simulator; the booster pressure building circuit comprises a liquid inlet valve, a liquid outlet valve, a fourth isolation valve, a pressure building master cylinder, a liquid supplementing valve and a second pressure sensor.
8. The system for diagnosing a fault in a booster pressure build-up circuit of a brake control system according to claim 7, wherein the fluid reservoir is communicated with a communication port of a simulation master cylinder, a first isolating valve is arranged on one group of communication pipes of the fluid reservoir and the simulation master cylinder, the communication port of the simulation master cylinder is communicated with the booster pressure build-up circuit, a group of second isolating valves are correspondingly arranged on a plurality of groups of communication pipes of the simulation master cylinder and the booster pressure build-up circuit, and a first pressure sensor is arranged on the communication pipes of the simulation master cylinder and the second isolating valves; the simulated master cylinder is communicated with a flow port of the pedal simulator, and a third isolation valve is arranged on a communicating pipeline of the simulated master cylinder and the pedal simulator.
9. The system for diagnosing a fault in a booster pump-up circuit of a brake control system according to claim 7, wherein a plurality of sets of said liquid inlet valves are correspondingly communicated with a plurality of sets of second isolating valves, a plurality of sets of said liquid outlet valves are correspondingly communicated with a plurality of sets of liquid inlet valves and a liquid storage pot, and a plurality of sets of fourth isolating valves are correspondingly arranged on the communicating pipes of each set of said liquid inlet valves and the third isolating valves; The fourth isolation valve is communicated with a flow port of the pressure building master cylinder, and a second pressure sensor is arranged on a communication pipeline between the fourth isolation valve and the pressure building master cylinder; The communication port of the pressure building main cylinder is communicated with the liquid storage kettle, and one group of communication pipelines of the pressure building main cylinder and the liquid storage kettle are provided with liquid supplementing valves.
10. The system according to claim 7, wherein the master cylinder is connected to a brake pedal, a displacement sensor is provided on the brake pedal, and each of the liquid inlet valve and the liquid outlet valve is connected to a brake end.

Description

Method and system for diagnosing faults of boosting pressure building loop of brake control system Technical Field The invention relates to the technical field of vehicle braking, in particular to a method and a system for diagnosing faults of a boosting pressure building loop of a braking control system. Background The drive-by-wire hydraulic control system collects control intention of operators and real-time working condition signals of equipment through sensors, and outputs electric signals to drive a valve to accurately adjust pressure, flow and oil flow direction of the hydraulic system after operation analysis and logic processing of an electric control unit, so that high-precision motion control of executing mechanisms such as a hydraulic cylinder and a hydraulic motor is realized. The hydraulic circuit of the existing drive-by-wire hydraulic control system mainly comprises a simulated master cylinder circuit and a booster pressure-building circuit, wherein the booster pressure-building circuit is responsible for building hydraulic pressure under normal booster working conditions and transmitting the hydraulic pressure to wheel cylinders to realize a braking function, and the simulated master cylinder circuit is used for building pressure to the wheel cylinders as a backup master cylinder to brake when the backup is invalid so as to ensure braking safety. In order to ensure the normal pressure building performance of the booster pressure building loop and maintain the reliable working state of the mechanical backup loop, the existing self-checking diagnosis method for the brake-by-wire system mostly adopts a pressure maintaining mode after pressure building to carry out leakage test or combines pressure and travel parameters in the pressure building process to detect the pressure-liquid quantity (P-V) characteristic of the brake loop, but the two methods cannot effectively detect the suck-back performance of the booster pressure building loop, once a vehicle runs on a road with a low attachment coefficient, a driver adopts emergency braking and triggers an ABS system due to sudden conditions, if the brake liquid in a booster cavity is consumed completely and the booster pressure building loop cannot realize effective suck-back of the brake liquid, the hydraulic brake system can directly lose the brake force output capability, and serious potential safety hazards of brake failure are caused. Disclosure of Invention The invention aims to solve the defects in the prior art, and provides a power-assisted pressure building loop fault diagnosis method and system of a brake control system. In order to achieve the above object, in a first aspect, the present invention provides a method for diagnosing a fault of a booster build-up circuit of a brake control system, including: acquiring a braking working condition parameter; judging and executing a self-checking liquid draining process to drain brake liquid based on the acquired brake working condition parameters; Executing a self-checking pressure building process and a self-checking back suction process to actively manufacture back suction working conditions, acquiring and evaluating air content, and judging the working state of the power-assisted pressure building loop. In some embodiments, the determining and executing the self-checking draining process to drain the brake fluid based on the acquired brake condition parameters includes: when the brake pedal is not stepped and the wheel rotating speed exceeds a set threshold value, actively opening a fourth isolation valve and closing a liquid inlet valve; The pressure-build master cylinder is driven to advance so that brake fluid flows through the fourth isolation valve, the second isolation valve, the simulation master cylinder and the first isolation valve into the reservoir. In some embodiments, the executing the self-checking pressure build-up process and the self-checking suck-back process to actively manufacture the suck-back condition includes: actively closing a fourth isolation valve to drive the pressure building master cylinder to compress; When the second pressure sensor detects that the internal pressure of the pressure building master cylinder reaches a first pressure threshold value P1, a corresponding first stroke value S1 is recorded, and a corresponding first Air content value Air1 is estimated; actively closing the fourth isolation valve, driving the pressure-building master cylinder to retract to a preset suction stroke, and then compressing again; When the second pressure sensor detects that the internal pressure of the pressure building master cylinder reaches the first pressure threshold value P1, a corresponding second stroke value S2 is recorded, and a corresponding second Air content value Air2 is evaluated. In some of these embodiments, the first Air content value Air1 and the second Air content value Air2 are calculated according to the following formulas: Air=(Volume1-Volume2)*