阅读说明：本技术 一种基于esc的液压制动泄漏检测方法及装置 (Hydraulic brake leakage detection method and device based on ESC ) 是由 黄建国 阮仁新 徐午 薛琼 吴颜翔 于 2021-07-28 设计创作，主要内容包括：本发明公开一种基于ESC的液压制动泄漏检测方法及装置,在整车上电和/或停车后,对ESC液压调节器的各个制动回路先施加制动压力,并保压一段时间,通过检测各个制动回路的压力降判断制动回路是否存在泄露。每个回路中有一个限压阀和两个增压阀,它们均为二位二通常开电磁阀,通电关闭；还有一个吸入阀和两个减压阀,它们均为二位二通常闭电磁阀,通电打开。本发明通过在起步前和停车后增加自动检测环节,采用直接自动检测压力降的方式,能客观、直接、及时获取泄漏情况,及时发现管路中存在的泄漏,并通过仪表警告信号提示驾驶员修复处理,防止行车过程中因制动液泄漏导致的制动性能下降或失效。(The invention discloses a hydraulic brake leakage detection method and a device based on ESC, after the whole vehicle is powered on and/or stopped, brake pressure is firstly applied to each brake loop of an ESC hydraulic regulator, the pressure is maintained for a period of time, and whether the brake loops leak or not is judged by detecting the pressure drop of each brake loop. Each loop is provided with a pressure limiting valve and two pressure increasing valves which are two-position two-way normally open electromagnetic valves and are closed when electrified; and the two pressure reducing valves are two-position two-way normally closed electromagnetic valves which are opened by electrifying. The invention adds automatic detection links before starting and after stopping, adopts a mode of directly and automatically detecting pressure drop, can objectively, directly and timely acquire leakage conditions, finds leakage in a pipeline in time, and prompts a driver to repair and process through an instrument warning signal, thereby preventing the brake performance from being reduced or invalid due to brake fluid leakage in the driving process.)

1. A hydraulic braking leakage detection method based on ESC is characterized in that: after the whole vehicle is electrified and/or stopped, brake pressure is firstly applied to each brake loop of the ESC hydraulic regulator, pressure is maintained for a period of time, and whether the brake loops leak or not is judged by detecting the pressure drop of each brake loop.

2. The ESC-based hydraulic brake leak detection method of claim 1, comprising the steps of:

s1, starting detection after the whole vehicle is electrified and/or stopped;

s2, reading the liquid level information of the brake oil can, if the liquid level of the brake oil can is normal, entering the next step, and if not, entering fault and disposal;

s3, sequentially reading gear position, vehicle speed and parking brake state information, if the gear position is neutral or P gear, the vehicle speed is 0, and the parking brake is not released, entering the next step, and if not, ending the detection;

s4, boosting each wheel cylinder, if the wheel cylinders can be normally boosted to a set pressure, entering the next step, and if not, entering fault and disposal;

s5, maintaining the pressure of each brake loop, entering the next step if the pressure maintaining time length reaches the set time, and returning to S2 if the pressure maintaining time length does not reach the set time;

s6, detecting the pressure drop of each brake circuit, if the pressure drop is larger than 0, entering the next step, and if not, ending the detection;

s6, failure and handling: recording storage faults and giving out fault warning, reducing pressure of each wheel cylinder, and finishing detection;

the pressure reduction of each wheel cylinder described in S5 and S6 refers to the pressure that is established for service braking in full contact with S4.

3. The ESC-based hydraulic brake leak detection method of claim 2, wherein: and in S1, after the vehicle is stopped, the delayed power supply supplies power.

4. The ESC-based hydraulic brake leak detection method of claim 2, wherein: the faults are classified into general faults and serious faults, wherein:

general failure: the pressure drop is less than or equal to a pressure drop set value;

serious failures include: if the pressure drop is larger than the pressure drop set value, the oil liquid in the brake oil can is lower than the minimum value.

5. The ESC-based hydraulic brake leak detection method of claim 4, wherein: if the fault is a general fault, controlling the running speed of the vehicle by requesting the engine to limit the vehicle speed; if the fault is serious, the vehicle is limited to start by limiting the torque and the rotating speed of the engine.

6. The ESC-based hydraulic brake leak detection method of claim 5, wherein: the parking brake is released using EPB restriction.

7. ESC-based hydraulic brake leak detection device to which the detection method of claims 1 to 6 is applied, characterized by comprising: two independent loops, wherein one loop is connected with the two front wheel cylinders, and the other loop is connected with the rear wheel cylinder; each circuit comprises:

the pump inlet is connected with the brake oil can through a suction valve, and the pump outlet is respectively connected with the two front wheel cylinders/the two rear wheel cylinders through the two pressure increasing valves;

a one-way valve is arranged between the pump inlet and each front wheel cylinder/rear wheel cylinder, and a pressure reducing valve is arranged between the one-way valve and each front wheel cylinder/rear wheel cylinder;

the outlet of the pump is connected with a brake oil can through a pressure limiting valve;

and a pressure sensor is arranged at the interface of each front wheel cylinder and each rear wheel cylinder, and the pressure sensor detects the pressure of each wheel cylinder in real time and transmits the pressure back to the controller.

8. The ESC-based hydraulic brake leak detection apparatus of claim 7, wherein: and an energy accumulator is arranged on a pipeline between the pressure reducing valve and the one-way valve.

9. The ESC-based hydraulic brake leak detection apparatus of claim 7, wherein: the pressure limiting valve and the pressure increasing valve are two-position two-way normally open electromagnetic valves; the suction valve and the pressure reducing valve are two-position two-way normally closed electromagnetic valves.

10. The ESC-based hydraulic brake leak detection apparatus of claim 9, wherein: the pressure increasing valve is connected with a one-way valve in parallel, and the outlet of the one-way valve is connected with the brake oil can; the pressure limiting valve is connected with a one-way valve in parallel, and the inlet of the one-way valve is connected with the brake oil can.

Technical Field

The invention belongs to the technical field of automobile braking, and particularly relates to a hydraulic braking leakage detection method and device based on an ESC (electronic stability control).

Background

The braking system is an important system for ensuring the driving safety, the reliability of the function and the performance of the braking system has important significance for the driving safety, and the reduction of the braking performance or the loss of the function can often cause various traffic accidents, so that the life and property safety of drivers and other road traffic participants can be endangered.

At present, the brake is mostly applied with acting force through air pressure and hydraulic pressure, so that braking force is generated to maintain safe vehicle speed when the vehicle decelerates or stops and goes downhill, and the air pressure and the hydraulic pressure need to be transmitted to the brake through a pipeline.

The hydraulic brake fluid reservoir is generally provided with a minimum fluid level warning device, and when the brake fluid level falls to the minimum fluid level line, a driver can be reminded in an instrument warning mode.

The air brake is generally provided with an air pressure warning device, and when the air pressure of the air storage cylinder is lower than a set value, a driver can be warned in an instrument warning mode.

A liquid level or air pressure warning may be caused by other reasons than leakage, such as wear of the friction plates, etc., which may also cause the liquid level to drop, so that a line leak is not the only cause for the occurrence of the warning. And the above warning will only be active when the liquid level reaches a lower level, which is not conducive to finding possible risks in time.

For the above reasons, the brake line needs to be checked regularly to ensure its proper function, in addition to being alerted by the warning device. But in fact except normal maintenance, the driver generally can not inspect the pipeline frequently, the pipeline is often difficult to find in time when leaking, and the leakage which can not be found in time becomes the potential safety hazard of driving.

It is common in the prior art to find possible leaks by setting a minimum liquid level, by checking the liquid level on a daily basis or by setting a minimum level sensor. However, there is a certain lag in determining whether there is a leak by the change in the brake fluid level, and when it is observed or detected that the brake fluid level has reached the lowest fluid level line, the leak has actually occurred to a certain extent, which is not conducive to finding the leak in time.

Chinese patent "a brake fluid leakage detection method, device and unmanned vehicle", publication No. CN111976694A, published japanese 2020.11.24, discloses a brake fluid leakage detection method, device and unmanned vehicle, relating to the field of unmanned driving technology, the method comprising: obtaining brake fluid volume information and brake fluid leakage information of a brake fluid storage tank according to a preset period; the brake fluid leakage information comprises brake deceleration information and/or brake fluid leakage speed information; determining leakage alarm information according to the brake fluid volume information and/or the brake fluid leakage information; and controlling the vehicle to run according to the leakage alarm information. The embodiment of the invention can realize the real-time detection of the volume of the brake fluid in the liquid storage tank, determine the alarm information according to the brake fluid leakage speed information, adopt the corresponding automatic driving measures, and can recognize the leakage fault of the brake system as early as possible, reduce the potential safety hazard and ensure the running safety of the vehicle.

The above patent determines whether or not a leak occurs based on a change in the brake fluid storage amount in the brake reservoir and a deviation of the braking deceleration from a set value. However, there is a delay in determining whether or not a leak occurs by a change in the amount of brake fluid stored, and when a drop in the brake fluid level is detected, the leak has actually occurred to a certain extent, which is not favorable for finding the leak situation in time. Whether leakage occurs or not is judged through deviation of the braking deceleration and a set value, and the accurate leakage situation is often difficult to obtain due to the influence of multiple factors such as vehicle weight change, pedal signal accuracy, road longitudinal slope, brake recession and the like.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a hydraulic brake leakage detection method and device based on ESC, which can automatically detect, and is safe and reliable.

In order to achieve the purpose, the invention designs an ESC-based hydraulic brake leakage detection method, which is characterized in that: after the whole vehicle is electrified and/or stopped, brake pressure is firstly applied to each brake loop of the ESC hydraulic regulator, pressure is maintained for a period of time, and whether the brake loops leak or not is judged by detecting the pressure drop of each brake loop.

Preferably, the detection method comprises the following steps:

s1, starting detection after the whole vehicle is electrified and/or stopped;

s2, reading the liquid level information of the brake oil can, if the liquid level of the brake oil can is normal, entering the next step, and if not, entering fault and disposal;

s3, sequentially reading gear position, vehicle speed and parking brake state information, if the gear position is neutral or P gear, the vehicle speed is 0, and the parking brake is not released, entering the next step, and if not, ending the detection;

s4, boosting each wheel cylinder, if the wheel cylinders can be normally boosted to a set pressure, entering the next step, and if not, entering fault and disposal; setting the pressure range to be 12 MPa-12 MPa according to the working pressure of the braking system;

s5, maintaining the pressure of each brake loop, entering the next step if the pressure maintaining time length reaches the set time, and returning to S2 if the pressure maintaining time length does not reach the set time; according to the longest braking duration from high-speed emergency braking to parking under various road conditions, the set time is 15-20 s;

s6, detecting the pressure drop of each brake circuit, if the pressure drop is larger than 0, entering the next step, and if not, ending the detection;

s6, failure and handling: recording storage faults and giving out fault warning, reducing pressure of each wheel cylinder, and finishing detection;

the pressure reduction of each wheel cylinder described in S5 and S6 refers to the pressure that is established for service braking in full contact with S4.

Preferably, in S1, the vehicle is powered by the delayed power supply after stopping.

Preferably, the faults are classified into general faults and serious faults, wherein:

general failure: the pressure drop is less than or equal to a pressure drop set value; the set value range of the pressure drop set value is generally more than 20% of the initial value, the pressure drop amplitude is larger than the set value in the braking process, the braking efficiency is obviously reduced, and the driving safety is influenced;

serious failures include: if the pressure drop is larger than the pressure drop set value, the oil liquid in the brake oil can is lower than the lowest value; the set value range is generally more than 50% of the initial value, and the braking efficiency is greatly reduced when the pressure drop amplitude is larger than the set value in the braking process, so that the driving safety is endangered.

Further preferably, in the event of a general failure, the vehicle running speed is controlled by requesting the engine to limit the vehicle speed.

Further preferably, if the fault is serious, the vehicle is limited to start by limiting the torque and the rotating speed of the engine.

It is further preferable that the parking brake is released using EPB restriction.

The ESC-based hydraulic brake leakage detection device applying the detection method is characterized by comprising the following steps: two independent loops, wherein one loop is connected with the two front wheel cylinders, and the other loop is connected with the rear wheel cylinder; each circuit comprises:

the pump inlet is connected with the brake oil can through a suction valve, and the pump outlet is respectively connected with the two front wheel cylinders/the two rear wheel cylinders through the two pressure increasing valves;

a one-way valve is arranged between the pump inlet and each front wheel cylinder/rear wheel cylinder, and a pressure reducing valve is arranged between the one-way valve and each front wheel cylinder/rear wheel cylinder;

the outlet of the pump is connected with a brake oil can through a pressure limiting valve;

and a pressure sensor is arranged at the interface of each front wheel cylinder and each rear wheel cylinder, and the pressure sensor detects the pressure of each wheel cylinder in real time and transmits the pressure back to the controller.

Preferably, an energy accumulator is arranged on a pipeline between the pressure reducing valve and the one-way valve.

Preferably, the pressure limiting valve and the pressure increasing valve are two-position two-way normally open electromagnetic valves.

Further preferably, the pressure increasing valve is connected with a one-way valve in parallel, and an outlet of the one-way valve is connected with the brake oil can.

Preferably, the pressure limiting valve is connected with a one-way valve in parallel, and an inlet of the one-way valve is connected with the brake oil can.

Preferably, the suction valve and the pressure reducing valve are two-position two-way normally closed solenoid valves.

The invention has the beneficial effects that: by adding automatic detection links before starting and after stopping and adopting a mode of directly and automatically detecting pressure drop, the leakage condition can be objectively, directly and timely obtained, the leakage existing in the pipeline can be timely found, and the instrument warning signal prompts a driver to repair and process, so that the brake performance reduction or failure caused by brake fluid leakage in the driving process can be prevented.

System leakage is detected by active pressurization and dwell before starting and after stopping. And the possible leakage risk of the system is timely discovered, and corresponding warning and treatment measures are taken for different leakage degrees. Through automatic frequent detection, replace artifical the detection, be favorable to in time discovering and repairing the leakage problem, reduce the intensity of labour of inspection work. If the fault is detected, measures such as vehicle speed limitation, starting limitation and the like are taken so as to ensure the driving safety.

Before starting and after stopping each time, the brake pressure is actively established and the pressure drop is automatically detected, and the fault severity grade is judged through the pressure drop in set time. And a starting limiting measure is taken for serious faults, and a vehicle speed limiting measure is taken for general faults.

Drawings

FIG. 1 is a schematic diagram of an ESC-based hydraulic brake leak detection arrangement of the present invention;

FIG. 2 is a schematic illustration of the pressurization process of the ESC-based hydraulic brake leak detection device of the present invention;

FIG. 3 is a schematic diagram of a pressure holding process of the ESC-based hydraulic brake leak detection device of the present invention;

FIG. 4 is a flow chart of an ESC-based hydraulic brake leak detection method of the present invention;

fig. 5 is a process flow diagram of the ESC-based hydraulic brake leak detection method of the present invention.

Detailed Description

The technical solutions of the present invention (including the preferred ones) are further described in detail by way of fig. 1 to 5 and enumerating some alternative embodiments of the present invention. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.

As shown in fig. 1, the ESC-based hydraulic brake leak detection apparatus includes: two independent loops-a front loop and a rear loop-the front loop is connected with the two front wheel cylinders and the rear loop is connected with the rear wheel cylinders; each loop is provided with a pressure limiting valve 1 and two pressure increasing valves 2 and 5 which are two-position two-way normally open electromagnetic valves and are closed when electrified; and the suction valve 3 and the two pressure reducing valves 6 and 8 are two-position two-way normally closed electromagnetic valves which are opened by electrifying.

In the following, the front circuit is taken as an example for detailed description, and the rear circuit has the same structure as the front circuit and is different only in the wheel cylinder connected thereto.

The front loops each include:

the pump 4 is provided with a pump inlet connected with a brake oil can 10 through an intake valve 3, a pump outlet connected with an FL wheel cylinder through a first pressure increasing valve 5, and a pump outlet connected with an FR wheel cylinder through a second pressure increasing valve 2;

a first pressure reducing valve 6 is arranged between the pump inlet and the FL wheel cylinder, and a second pressure reducing valve 8 is arranged between the pump inlet and the FR wheel cylinder; one-way valves are arranged between the first pressure reducing valve 6 and the second pressure reducing valve 8 and the pump inlet, and an energy accumulator is arranged on a pipeline at the inlet of the one-way valves;

the outlet of the pump is connected with a brake oil can through a pressure limiting valve 1; the pressure limiting valve 1 is connected with a one-way valve in parallel, and an inlet of the one-way valve is connected with the brake oil can.

And the interfaces of the FL wheel cylinder are respectively provided with a first pressure sensor 7, the interfaces of the FR wheel cylinder are respectively provided with a second pressure sensor 8, and the pressure sensors 7 and 8 detect the pressures of the FL wheel cylinder and the FR wheel cylinder in real time and transmit the pressures back to the controller.

Preferably, the first pressure increasing valve 5 and the second pressure increasing valve 6 are both connected with a one-way valve in parallel, and the outlet of the one-way valve is connected with the brake oil can.

When the brake is normally braked, all the electromagnetic valves are not electrified, and the brake hydraulic pressure from the brake master cylinder enters the inlet, passes through the pressure regulator and then respectively enters all the brake wheel cylinders through the outlet. The brake oil pot to FL wheel cylinder circuit will be described in detail below as an example.

As shown in fig. 2, the supercharging process: the pressure limiting valve 1 is powered on and closed, the suction valve 3 is powered on and opened, the first pressure increasing valve 5 is kept powered off and opened, the motor is powered on to drive the pump 4 to work, brake fluid is pumped into the FL wheel cylinder from the master cylinder, namely the brake oil can, through the suction valve 3, the pump 4 and the first pressure increasing valve 5, and active establishment of pressure of the FL wheel cylinder is achieved. The pressure active establishment modes of the FR, RL and RR circuits are the same, and the working states of the pump and the corresponding solenoid valves are only required to be controlled.

As shown in fig. 3, the pressure holding process: the pressure-limiting valve 1 is closed by energization, the suction valve 3 is closed by deenergization, the pressure-increasing valve 5 is closed by energization, and the circuit between the master cylinder and the wheel cylinder FL is cut off so that the wheel cylinder pressure is kept constant. At this time, the motor is still energized to drive the pump 4 to operate, but since the suction valve 3 separates the pump inlet from the master cylinder, even if the pump 4 is operating (if the pump 4 is required to operate in another circuit), the brake fluid cannot be pumped from the master cylinder to the wheel cylinder FL, the pressure at the outlet of the pump 4 does not increase, and the wheel cylinder FL pressure is maintained at the set value. The pressure of the FR, RL and RR circuits is kept the same, and only the working state of the corresponding solenoid valve needs to be controlled.

As shown in fig. 1, the pressure reduction process: all the electromagnetic valves are kept in an initial state, namely a power-off state, and the motor also stops working. At this time, since the driver does not depress the brake pedal, and the master cylinder does not have any pressure, that is, the master cylinder pressure is lower than the wheel cylinder pressure, the brake fluid in the FL wheel cylinder returns to the master cylinder directly through the first pressure increase valve 5 and the pressure limit valve 1 by the pressure difference, and the FL wheel cylinder pressure is reduced. The pressure reduction processes of the FR, RL and RR circuits are the same, and only the working states of corresponding electromagnetic valves need to be controlled.

As shown in fig. 4, in the hydraulic brake leakage detection method based on the ESC of the present invention, after the entire vehicle is powered on and/or stopped, the brake pressure is applied to each brake circuit of the ESC hydraulic regulator, and the pressure is maintained for a period of time, and whether the brake circuit leaks is determined by detecting the pressure drop of each brake circuit.

The invention comprises pre-starting detection and post-stopping detection.

Detecting before starting:

before the vehicle starts, after the vehicle completes power-on self-test, if the liquid level of the brake oil can is not too low, the controller judges whether to implement a leakage detection process according to the read vehicle speed, gear and parking brake state information.

And if the system pressurization can not reach a set value, determining the fault level as a serious fault, and entering a disposal measure. Definition of a critical failure: this may lead to a failure in which the braking capability is greatly reduced and the driving safety may be compromised.

After entering the leakage detection, if the information of the gear, the vehicle speed and the parking brake state is detected to be changed, which means that the driver has a starting intention or starts to start, the detection process is exited.

And if the driver does not perform starting operation within the set time, judging whether leakage exists according to the pressure drop, determining a corresponding fault level according to the leakage condition and taking corresponding treatment measures.

And (3) detection after parking:

after the automobile is parked, a driver can turn off the power supply, so that a delay power supply needs to be accessed, and the system can work for a period of time after the power supply is turned off.

After the vehicle is stopped and powered off, the time-delay power supply continues to work, and the same leakage detection process as before starting is implemented.

Preferably, the detection method comprises the following steps:

s1, starting detection after the whole vehicle is electrified and/or stopped;

s2, reading the liquid level information of the brake oil can, if the liquid level of the brake oil can is normal, entering the next step, and if not, entering fault and disposal;

s3, sequentially reading gear position, vehicle speed and parking brake state information, if the gear position is neutral or P gear, the vehicle speed is 0, and the parking brake is not released, entering the next step, and if not, ending the detection;

s4, boosting each wheel cylinder, if the wheel cylinders can be normally boosted to a set pressure, entering the next step, and if not, entering fault and disposal; setting the pressure range to be 12 MPa-12 MPa according to the working pressure of the braking system;

s5, maintaining the pressure of each brake loop, entering the next step if the pressure maintaining time length reaches the set time, and returning to S2 if the pressure maintaining time length does not reach the set time; (ii) a According to the longest braking duration from high-speed emergency braking to parking under various road conditions, the set time is 15-20 s;

s6, detecting the pressure drop of each brake circuit, if the pressure drop is larger than 0, entering the next step, and if not, ending the detection;

s6, failure and handling: recording storage faults and giving out fault warning, reducing pressure of each wheel cylinder, and finishing detection;

the pressure reduction of each wheel cylinder described in S5 and S6 refers to the pressure that is established for service braking in full contact with S4.

As shown in fig. 4 and 5, the failures are classified into general failures and serious failures, in which:

definition of a critical failure: the braking capability can be greatly reduced, and the driving safety can be endangered; general fault definition: the braking capability can be slightly reduced, and the driving safety can not be endangered after the braking capability is timely processed;

specifically, the method comprises the following steps:

general failure: the pressure drop is less than or equal to a pressure drop set value; the set value range of the pressure drop set value is generally more than 20% of the initial value, the pressure drop amplitude is larger than the set value in the braking process, the braking efficiency is obviously reduced, and the driving safety is influenced;

serious failures include: if the pressure drop is larger than the pressure drop set value, the range of the oil in the brake oil can which is lower than the minimum set value is generally more than 50% of the initial value, and the pressure drop amplitude is larger than the value in the braking process, the braking efficiency is greatly reduced, and the driving safety is endangered.

In the case of a general failure, the vehicle running speed is controlled by requesting the engine to limit the vehicle speed.

If the fault is serious, the vehicle is limited to start by limiting the torque and the rotating speed of the engine. Preferably, the parking brake is released using EPB restriction.

Before starting and after stopping each time, the invention actively establishes braking pressure and automatically detects pressure drop, and judges the fault severity grade through the pressure drop in set time. And a starting limiting measure is taken for serious faults, and a vehicle speed limiting measure is taken for general faults.

The output port of each loop is internally provided with a pressure sensor;

the detection frequency of the invention is before starting and after stopping each time;

the invention judges whether to implement detection according to the information of vehicle speed, accelerator, gear, parking brake state and the like;

the invention actively builds brake pressure and automatically detects pressure drop;

the invention judges the severity level of the fault through the pressure drop in the set time;

the invention adopts measures of limiting engine torque and limiting EPB release and the like to limit starting and issue warning information for serious faults, and adopts measures of limiting vehicle speed and issuing warning information for general faults.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and any modification, combination, replacement, or improvement made within the spirit and principle of the present invention is included in the scope of the present invention.