KR20120053212A

KR20120053212A - Control method of electronic-brake-force-distribution

Info

Publication number: KR20120053212A
Application number: KR1020100114369A
Authority: KR
Inventors: 조성현
Original assignee: 현대자동차주식회사
Priority date: 2010-11-17
Filing date: 2010-11-17
Publication date: 2012-05-25

Abstract

The present invention relates to a control method of an EBD system in addition to the ABS to distribute the hydraulic pressure provided to the hydraulic unit to the brake devices mounted on the respective wheels, the load distributed to each wheel in accordance with the loading load of the vehicle in the stationary state Determining an initial braking pressure (P0) of the wheels; and detecting a braking deceleration and lateral acceleration of the vehicle when a braking signal is input; and an initial braking pressure (P0) and a braking deceleration and lateral acceleration. Calculating a limit braking pressure (P1) of each wheel by calculating a function according to a predetermined logic; And increasing the hydraulic pressure provided to the brake devices of the respective wheels below the limit braking pressure P1.
The present invention of the above configuration, by distributing the braking force in consideration of the load distribution and driving state of the vehicle can provide the optimum braking force, to prevent the wheellock and to avoid unnecessary decompression and pressure increase (ABS operation) process It can be effective.

Description

Control method of ECD system {Control method of Electronic-Brake-Force-Distribution}

The present invention relates to a control method of an electronic-brake-force-distribution (EDB) system, and more particularly, to prevent wheel lock in consideration of the change in load of the vehicle and the lateral acceleration generated when the vehicle is turning. The present invention relates to a control method of an EBD system that improves braking stability by distributing braking force.

In order to ensure braking stability, the vehicle is equipped with an anti-lock break system (ABS) to suppress the occurrence of wheel locks (wheels stop rotating but slip due to slippage between the ground and the tires).

ABS is a system that prevents slipping by wheellock by repeatedly reducing pressure-increasing brake hydraulic pressure by detecting a slip phenomenon that may occur during braking on a road where frictional force is reduced such as sudden braking or snow and rain. The ABS prevents wheel locks of all wheels during sudden braking, thereby ensuring steering power, and stably brakes the vehicle even when turning or when the road conditions of the wheels are different.

On the other hand, a brake system of a passenger vehicle generally boosts the pedal pedal's foot force (by pneumatic pressure) and pressurizes the piston of the master cylinder so that hydraulic pressure is generated, and the brake pad is applied to a disk or drum rotating with the wheel by using the hydraulic pressure. To brake the vehicle. And, ABS is applied to the vehicle is a hydraulic unit (hydraulic unit) for distributing the hydraulic pressure of the master cylinder to the brakes of each wheel, a wheel speed sensor for detecting the speed of each wheel, a wheel speed sensor and communicates with the hydraulic unit It further includes an ABS ECU to control.

However, the optimum braking force required for each wheel will always depend on the occupants of the vehicle and the degree of cargo loading. That is, the braking force is a force that prevents the tire from rotating on the road surface, and each wheel suppresses wheel lock generation according to the applied load, and the hydraulic pressure required to lower the braking distance is different.

The EBD system is designed to increase the performance and safety of ABS by automatically distributing the appropriate braking force to the front and rear wheels according to the load on the vehicle. In other words, the EBD system is not a separate system from ABS. It is a system added to ABS. If the braking force (set in ABS) is not balanced according to the load change of the vehicle, the braking force of the rear wheel additionally controls the optimum braking force. It is a system that helps to reach the system, using the hydraulic unit and wheel speed sensor used in ABS but adding new control logic to the ABS ECU.

However, the conventional EBD system determines the braking pressure of the rear wheel in consideration of the loading load of the vehicle. However, when the wheel lock occurs on the rear wheel (because the frictional force of the ground is changed), the braking pressure cannot be adjusted. Therefore, only the distribution between the front wheel and the rear wheel is performed, so the distribution between the left wheel and the right wheel is not considered.

Accordingly, the present invention is to provide a control method of the EBD system that can provide the optimum braking force even when turning the vehicle considering the front and rear direction as well as the left and right directions of the vehicle.

The present invention for achieving the above object, in the control method of the EBD system for distributing the hydraulic pressure provided to the hydraulic unit in addition to the ABS to the brake devices mounted on the respective wheels, the load load of the vehicle in the stationary state Determining an initial braking pressure (P0) of the wheels (to be distributed to the brake device) based on the load distributed to each wheel according to the present invention; and detecting a braking deceleration and lateral acceleration of the vehicle when a braking signal is input. Calculating the limit braking pressure P1 of each wheel by calculating the initial braking pressure P0, the braking deceleration, and the lateral acceleration according to a predetermined logic; And increasing the hydraulic pressure provided to the brake devices of the respective wheels below the limit braking pressure P1.

The limit braking pressure is the hydraulic pressure at which wheel lock occurs in the wheel when provided to the brake device.

When the wheel lock is generated, the boosting of the brake devices is stopped and the EBD is terminated, and the ABS of the normal function operates.

In addition, the braking deceleration is sensed by sensing the weight change amount of the front wheel and the rear wheel, the lateral acceleration is sensed by sensing the weight change amount of the left wheel and the right wheel.

The present invention of the above configuration, by distributing the braking force in consideration of the load distribution and driving state of the vehicle can provide the optimum braking force, to prevent the wheellock and to avoid unnecessary decompression and pressure increase (ABS operation) process It can be effective.

Therefore, it is possible to shorten the braking distance and maximize the braking stability.

1 is a flow chart illustrating a procedure for controlling an EBD system according to a preferred embodiment of the present invention.

Hereinafter, the control method of the EBD system according to a preferred embodiment of the present invention will be described in more detail.

Referring to FIG. 1, the control method of the present invention detects a vehicle stop (through sensing such as an ABS wheel speed sensor), and detects a vehicle's posture, a height of each axle, and an axle relative to a preset tolerance state. The weight distribution acting determines the weight distribution ratio acting on the wheel. The distribution ratios acting on each wheel are divided into four wheels. The change is measured by a known gyro sensor, a gravity sensor, a load sensor and the like, and the distribution ratio is braked at the bump / rebound of the suspensions of the respective parts. The effect is also considered and determined.

Based on this distribution ratio, the initial braking pressure P0 is determined for each wheel. The initial braking pressure (P0) is a hydraulic pressure that the brake device (such as a caliper or wheel cylinder) coupled to the wheel can provide the optimum braking force, the initial agent acting on each wheel according to the load applied to the wheel Dynamic pressures are determined. For example, the initial braking pressure of the left rear wheel, in which the weight is loaded in the trunk and the load acting on the left rear wheel, is determined to be larger than the other wheels.

This initial braking pressure P0 is stored in the ECU controlling the EBD. When the driver's braking intention is detected through a pedal stroke sensor, a pedal travel sensor, and a pressure sensor when the vehicle is in operation (when the driver releases the brake pedal), In braking, the measurement of forward and backward braking deceleration and lateral acceleration of the vehicle starts. Front and rear braking deceleration and lateral acceleration are sensed through known G-sensors and / or yaw rate sensors, etc., and when the measured values are received by the ECU as electrical signals, the ECU is predetermined logic. Calculate the limit braking pressure (P1) of each wheel based on the initial braking pressure (P0) according to the and setting. The G-sensor and / or yaw rate sensor senses the amount of change in the weight of the front and rear wheels to sense the braking deceleration, and senses the amount of change in the left and right wheels of the front and rear wheels to sense the lateral acceleration.

The limit braking pressure (P1) is the hydraulic pressure provided to the brake device when a wheel lock phenomenon occurs between the tire and the ground, the calculation formula and data for the logic and setting values are repeated for each situation in the construction of the EBD system Accumulated through experiment and stored in ECU.

The ECU distributes the hydraulic pressure to each of the wheels up to the limit braking pressure P1. The limit braking pressure (P1) of each wheel will be different according to the vehicle speed and load load, so the braking hydraulic pressure (P) provided to each brake device is sensed independently in all four places, and each limit braking pressure The pressure is increased to less than P1. The boosted braking hydraulic pressure P is maintained in a boosted state until the vehicle is completely braked.

At this time, the difference between the boosted braking hydraulic pressure (P) and the limit braking pressure (P1) is minute, but the degree may vary according to a preset value.

Therefore, the EBD system according to the present invention maintains a situation where no slip is generated between the tire and the ground without the operation of ABS since the braking hydraulic pressure P does not reach the limit braking pressure P1 (since no wheel lock occurs). To provide braking power.

However, if the road surface changes due to the increase of the braking hydraulic pressure (P) or during the increase of pressure (for example, when passing through a puddle or ice sheet), the EBD system terminates and the normal ABS function This is done.

As described above, the embodiments disclosed in the specification and the drawings are only presented as specific examples to aid the understanding of the present invention, and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

Claims

In the control method of the EBD system that distributes the hydraulic pressure provided to the hydraulic unit in addition to the ABS to the brake devices mounted on the respective wheels,
Determining an initial braking pressure (P0) of the wheels based on the loads distributed to the wheels according to the load of the vehicle in the stopped state;
Detecting braking deceleration and lateral acceleration of the vehicle when a braking signal is input;
Calculating the threshold braking pressure P1 of each wheel by calculating the initial braking pressure P0, the braking deceleration, and the lateral acceleration according to a predetermined logic;
Increasing the hydraulic pressure provided to the brake devices of the respective wheels below the limit braking pressure (P1).

The method of claim 1, wherein the limit braking pressure is a hydraulic pressure that generates a wheel lock on a wheel when the brake device is provided to the brake device.

The control method according to claim 1 or 2, wherein when the wheel lock is generated, the EBD system is terminated and the ABS is operated.

The control method of claim 3, wherein the braking deceleration is sensed by sensing a weight change amount of the front wheel and the rear wheel, and the lateral acceleration is sensed by sensing a weight change amount of the left wheel and the right wheel.