KR20150086968A - Method to estimate master cylinder pressure of brake - Google Patents

Abstract

The present invention relates to a method for estimating the pressure of a master cylinder of a brake. The method comprises: a detecting step of detecting a displacement value of a pedal and vacuum pressure during the operation of the pedal; a comparing step of comparing the detected vacuum pressure with a target vacuum pressure; a mapping step of applying and mapping with a master cylinder pressure by the detected vacuum pressure level; and a compensating step of compensating for a brake pedal change rate into master cylinder compensation pressure using a brake pedal displacement value. Therefore, the method for estimating the pressure of a master cylinder of a brake can improve the performance of estimating the pressure of a master cylinder by compensating for the pressure of the master cylinder using the brake pedal change rate, the pressure value, and a wheel brake pressure, and can prevent the degradation of an electronic control brake system.

Description

METHOD TO ESTIMATE MASTER CYLINDER PRESSURE OF BRAKE [0002]

More particularly, the present invention relates to a master cylinder pressure estimation method for a brake capable of calculating a master cylinder pressure signal by combining a brake pedal signal, a brake pedal change rate signal, a negative pressure signal, Estimation method.

Recently, the development of hybrid vehicles, fuel cell vehicles, electric vehicles, etc. has been completed or underway to improve fuel efficiency and reduce exhaust gas emissions. In such a vehicle, a braking device, that is, a brake, is essentially installed. The vehicle brakes are devices that reduce the speed of a running car or stop the car.

In the hydraulic brakes generating the braking force by using the hydraulic pressure among the vehicle brakes, when the driver depresses the pedal, the control unit senses this, and by operating the hydraulic control unit to supply the hydraulic pressure to the master cylinder, To generate braking force.

Such an electronically controlled hydraulic brake includes a master cylinder connected to a brake pedal, a wheel cylinder mounted on the front and rear wheels and equipped with a pressure sensor, and a plurality of solenoid valves for controlling the hydraulic pressure supplied to the wheel cylinder When the driver presses the brake pedal, hydraulic pressure is generated in the master cylinder and supplied to the wheel cylinder, and the wheel cylinder presses and stops the brake lining.

Such a conventional brake performs a two-dimensional mapping of a brake pedal signal and a master cylinder pressure signal in a vehicle equipped with a brake pedal sensor to estimate the master cylinder pressure signal to determine the driver's braking commitment and required braking amount, There is a large error in estimating different master cylinder pressures depending on the pedal change rate, the vacuum level, and the wheel residual pressure. This error has a problem in that the performance of the electronically controlled braking system is reduced in relation to the entry point and the control amount of the electromagnetic brake system.

Korean Patent Publication No. 10-2008-0086249 (September 25, 2008)

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and it is an object of the present invention to provide a hydraulic control system, Which can compensate for the difference between the master cylinder pressure and the master cylinder pressure.

According to an aspect of the present invention, there is provided a vehicular brake system comprising a pedal sensor provided in a brake pedal and detecting a displacement value of a pedal when a driver presses the pedal, An electronic control unit for calculating a compensation pressure, and a brake assist system (BAS) for mapping the pressure of the master cylinder according to the vacuum pressure level to a value calculated by the electronic control unit.

The electronic control unit preferably includes a compensating pressure calculating unit for calculating the compensating pressure of the master cylinder from the pedal displacement value transmitted from the pedal sensor and calculating the compensating pressure for the master cylinder by the wheel braking pressure.

A step of detecting a pedal displacement value and a vacuum pressure generated during braking when the pedal is operated; a comparison step of comparing the detected vacuum pressure with a target vacuum pressure; And a compensating step of compensating the brake pedal change rate by the master cylinder compensating pressure with the brake pedal displacement value.

Mapping the master cylinder pressure for each of the vacuum pressure deficiency levels when the detected vacuum pressure is smaller than the target vacuum pressure, determining a master cylinder pressure for each normal vacuum pressure when the detected vacuum pressure is greater than or equal to the target vacuum pressure, It is preferable to include a step of mapping the cylinder pressure.

The method further includes determining whether a braking pressure of the wheel is present based on the wheel pressure estimated in the driver's non-braking state, and compensating the braking pressure of the wheel with the master cylinder pressure if the braking pressure of the wheel is present desirable.

It is preferable that the compensation pressure calculation unit further includes an arithmetic step of calculating a compensation pressure for compensating the braking pressure of the wheel with the master cylinder pressure between the determination step and the compensation step.

According to the present invention, the master cylinder pressure estimation performance can be improved by compensating the brake pedal change rate, the booster pressure value and the pressure of the master cylinder by the wheel brake pressure, thereby preventing the performance of the electronically controlled brake system from being deteriorated You can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating a pressure relationship at two points in a flow path according to one embodiment of the present invention. FIG.
2 is a block diagram showing a master cylinder pressure estimation apparatus according to an embodiment of the present invention.
3 is a flowchart showing a master cylinder compensation pressure estimation method for a vehicle brake according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms described below are terms defined in consideration of the functions of the present invention, which may vary depending on the intention or custom of the user, the operator. Therefore, definitions of these terms should be made based on the contents throughout this specification.

2 is a block diagram of a master cylinder pressure estimating apparatus according to an embodiment of the present invention. Referring to FIG. 1, 3 is a flowchart illustrating a method of estimating a master cylinder compensation pressure of a vehicle brake according to an embodiment of the present invention.

The master cylinder pressure estimation and control apparatus for a vehicle brake according to an embodiment of the present invention includes a pedal sensor 110, a compensation pressure calculation unit 150, an electronic control unit 140, and a brake assist system (BAS) .

The pedal sensor 110 is provided on a pedal for pressing the brake pedal by the driver, and detects the displacement value of the pedal when the driver depresses the pedal. The pedal sensor 110 transmits the displacement value of the pedal to the compensation pressure calculation unit 150 described later.

The compensation pressure calculation unit 150 receives the pedal displacement value from the pedal sensor 110, calculates a compensated vacuum pressure for the rate of change of the brake pedal, and transmits the compensated pressure to the electronic control unit 140. Then, the compensation pressure calculation unit 150 calculates the braking pressure of the wheel at a compensation pressure for the vacuum pressure, and then transmits the compensation pressure to the electronic control unit 140.

The electronic control unit 140 is configured to receive various kinds of information from the respective parts used in the brake operation of the vehicle. That is, the electronic control unit 140 is configured to receive the displacement value of the pedal when the driver depresses the brake pedal from the pedal sensor 110 that detects the displacement of the brake pedal. The electronic control unit 140 is configured to receive the vacuum pressure signal.

The vacuum pressure signal is a value with respect to the vacuum pressure generated from the vacuum generating mechanism, and is detected and generated by the vacuum pressure detecting unit 120 provided in the vacuum pressure generating mechanism. Generally, the vacuum pressure is generated in the booster by the pressure generated to increase the force exerted on the pedal when the brake is operated. However, in the case of electric or hybrid vehicles, the braking pressure is generated by the braking pressure generated from the AHB (Active Hydraulic Booster) . Thus, the vacuum generating mechanism in one embodiment of the present invention includes a booster and an AHB.

The vacuum pressure in the embodiment of the present invention is one example that is generated in the booster.

Here, the electronic control unit 140 includes a compensation pressure calculation unit 150 for calculating the compensation pressure of the master cylinder from the brake pedal displacement value and calculating the compensation pressure of the master cylinder from the brake pressure of the wheel.

The BAS 160 serves to map the pressure of the master cylinder by the vacuum pressure level to the value calculated by the electronic control unit 140. [

Here, when the driver depresses the brake pedal, the compensation pressure for the rate of change of the pedal is derived by the equation shown in Fig. 1 and the following.

In the flow path of FIG. 1 and the following equation, D represents a flow path width, L represents a distance between two point pressures, P ₁ represents a master cylinder pressure, P ₂ represents a wheel pressure, a represents acceleration, and rho represents fluid density.

That is, when the driver quickly depresses the brake pedal, acceleration occurs between the two points. In this way, the pressure at one point is expressed by the sum of the basic pressure and the compensation pressure using the acceleration as the pressure.

A method for estimating a pressure of a master cylinder for a vehicle according to an embodiment of the present invention includes steps of detecting a displacement value of a brake pedal, detecting a vacuum pressure (S100), comparing the detected vacuum pressure with a target vacuum pressure A mapping step S130 for mapping and applying the master cylinder pressure according to the detected vacuum pressure level, and a step S140 for compensating for the brake pedal change rate with the master cylinder compensation pressure.

First, when the driver presses the brake pedal to operate the brake, the pedal sensor 110 provided on the brake pedal detects the brake operation and transmits the brake operation to the electronic control unit 140.

Then, the operation of the pedal causes the vacuum pressure detector 120 to detect the vacuum pressure and transmit the vacuum pressure to the electronic controller 140.

Thereafter, the electronic control unit 140 has a step of comparing the vacuum pressure delivered from the vacuum pressure detection unit 120 with the target vacuum pressure (S110)

That is, after comparing the detected vacuum pressure with the target vacuum pressure, the electronic controller 140 maps the master cylinder pressure to the vacuum pressure level that is insufficient when the detected vacuum pressure is less than the target vacuum pressure. If the detected vacuum pressure is equal to or greater than the target vacuum pressure, the brake pedal-master cylinder pressure is mapped to the normal vacuum pressure level (S130)

Thereafter, compensating the displacement of the pedal detected at the time of operation of the brake pedal with the compensation pressure of the master cylinder with respect to the rate of change of the brake pedal. (140)

That is, the pressure compensating step 140 includes calculating the compensating pressure of the master cylinder with respect to the brake pedal change rate from the displacement value of the pedal detected from the pedal sensor 110 by the compensating pressure calculating unit 150. [

Thereafter, the step of determining whether the braking pressure of the wheel is present from the braking pressure of the wheel when the driver does not operate the pedal, that is, in the non-braking state of the driver,

That is, it is determined whether the braking pressure of the wheel remains from the braking pressure of the wheel when the driver does not operate the pedal.

Here, the braking pressure of the wheel is the pressure value of the estimated wheel, and the pressure value of the estimated wheel is transmitted to the wheel pressure value calculated in the electronic stability control (ESC) system provided in the vehicle. This ESC is a known technique, and a detailed description of its structure and operation will be omitted. The ESC is configured to transmit the pressure value of the wheel to a vehicle network that receives general information from various devices provided in the vehicle when the vehicle is operated. Accordingly, the electronic control unit 140 is configured to receive the wheel pressure value from the vehicle network.

Thereafter, when the braking pressure of the wheel is present, it has a step of compensating the braking pressure of the wheel by the master cylinder pressure (S160)

Between the step S150 of judging whether the braking pressure of the wheel exists or not and the step S160 of compensating by the master cylinder pressure, when the wheel braking pressure is detected by the wheel pressure sensor, the remaining pressure of the wheel is set to the master cylinder pressure And calculating a compensation pressure for compensating the pressure. That is, the calculation step is to calculate the compensation pressure for compensating the master cylinder pressure to the wheel residual pressure after the compensation pressure calculation unit 150 receives the residual pressure of the wheel from the wheel pressure sensor 130.

As described above, it is possible to improve the master cylinder pressure estimation performance by compensating the brake pedal change rate, the booster pressure value and the pressure of the master cylinder by the wheel brake pressure, thereby preventing the performance of the electronically controlled brake system from being deteriorated It is.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. It is understandable. Accordingly, the true scope of the present invention should be determined by the following claims.

110: Pedal sensor
120: vacuum pressure detector
140:
150: Compensation pressure calculating section
160: BAS

Claims (6)

A pedal sensor provided in the brake pedal and detecting a displacement value of the pedal when the driver depresses the pedal;
An electronic control unit for calculating a displacement value of the pedal and a compensation pressure for compensating the pressure of the master cylinder from the vacuum pressure;
A Brake Assist System (BAS) for mapping the pressure of the master cylinder by the vacuum pressure level to the value calculated by the electronic control unit;
Wherein the master cylinder compensating pressure estimating means estimates the master cylinder compensating pressure of the vehicle brake. The method according to claim 1,
The electronic control unit,
And a compensating pressure calculating unit for calculating a compensating pressure of the master cylinder from the pedal displacement value transmitted from the pedal sensor and calculating a compensating pressure for the master cylinder by the wheel braking pressure, Device. A detecting step of detecting a pedal displacement value and a vacuum pressure generated during braking when the pedal is operated;
A comparison step of comparing the detected vacuum pressure with a target vacuum pressure;
A mapping step of mapping and applying the master cylinder pressure to the detected vacuum pressure level;
A compensating step of compensating the rate of brake pedal change with the master cylinder compensating pressure by the brake pedal displacement value;
Wherein the master cylinder compensating pressure estimating means estimates the master cylinder compensating pressure of the vehicle brake. The method of claim 3,
In the mapping step,
Mapping the master cylinder pressure to the vacuum pressure deficiency level if the detected vacuum pressure is less than the target vacuum pressure;
Mapping the master cylinder pressure by normal vacuum pressure when the detected vacuum pressure is greater than or equal to the target vacuum pressure;
Wherein the master cylinder compensating pressure estimating means estimates the master cylinder compensating pressure of the vehicle brake. The method of claim 3,
Determining whether a braking pressure of the wheel is present based on an estimated wheel pressure in a non-braking state of the driver;
Compensating the braking pressure of the wheel with the master cylinder pressure if the braking pressure of the wheel is present;
Wherein the master cylinder compensating pressure estimating means estimates the master cylinder compensating pressure of the vehicle brake. The method of claim 5,
Between the judgment step and the compensation step,
Further comprising a calculating step of calculating a compensating pressure for compensating the braking pressure of the wheel by the master cylinder pressure in the compensating pressure calculating unit.

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