KR20080022471A - A method of preventing vehilce roll-back on the slope for a vehicle - Google Patents

Abstract

A method for preventing roll-back of a vehicle on a slope is provided to facilitate start of the vehicle by properly providing the amount of braking pressure when the vehicle starts after stops. A method for preventing roll-back of a vehicle on a slope comprises a step of determining if roll-back of the vehicle has occurred when the vehicle starts after stopping on the slope(S102). When the roll-back of the vehicle has occurred, target pressure amount is determined corresponding to the degree of the roll-back of the vehicle(S105). The determined target pressure amount is generated to prevent the roll-back of the vehicle. The degree of the roll-back of the vehicle is calculated from the speed of the vehicle and an inclination angle of the slope.

Description

How to prevent road slopes in vehicles {A METHOD OF PREVENTING VEHILCE ROLL-BACK ON THE SLOPE FOR A VEHICLE}

1 is an ABS hydraulic circuit diagram applied to the vehicle slope pushing device of the present invention.

2 is a control block diagram of a slope rolling apparatus of a vehicle according to an embodiment of the present invention.

3 is a control flowchart of a method of preventing a slope of a vehicle according to an exemplary embodiment of the present invention.

FIG. 4 is a graph for explaining that the amount of braking pressure varies depending on the degree of vehicle slippage when there is vehicle slippage at the time of departure after stopping at the slope.

* Description of the symbols for the main functions of the drawings *

10: electronic control unit 11: main controller

12: input interface 13: output interface

24: G sensor 30: valve and motor controller

The present invention relates to a method of preventing slope rolling of a vehicle. More particularly, the present invention relates to a method of preventing slope rolling of a vehicle that can automatically prevent the vehicle from being pushed by detecting that the vehicle is pushed backward at the start of the ramp after stopping.

Conventionally, when starting a vehicle stopped on an inclined hill, the brake pressure is applied to each wheel by using an electronic brake device that senses that the vehicle is pushed backward from the wheel speed sensor mounted on each wheel and provides the brake pressure to each wheel. To prevent the vehicle from being pushed back.

However, the conventional method is to provide a predetermined amount of braking pressure to each wheel without accurate information about the degree of sliding of the vehicle according to the road surface slope of the stopped vehicle, there is a fear that the vehicle is pushed when the braking pressure is insufficient. If the amount is excessive, there is a problem that it may be rather uncomfortable for the driver proficient in starting the hill road by obstructing the departure of the vehicle.

The present invention is to solve the above-mentioned problems, an object of the present invention is to smoothly start the vehicle while effectively preventing vehicle rolling by varying the amount of braking pressure provided to brake each wheel when the vehicle is stopped at an incline. It is to provide a method for preventing the slope of the vehicle can be.

In order to achieve the above object, the ramp rolling prevention method of the vehicle of the present invention provides a brake pressure rolling method for braking the vehicle by providing a braking pressure to each wheel, when the vehicle starts after the ramp stops, vehicle rolling occurs If it is determined whether the vehicle is pushed, the target pressure amount corresponding to the degree of the vehicle is determined, and the determined target pressure is generated to prevent the vehicle from rolling.

At this time, the braking pressure is increased to reach the target braking pressure amount, and the target pressure amount is maintained after reaching the target pressure amount.

At this time, the degree of rolling of the vehicle is characterized in that it is calculated from the vehicle speed and road slope.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

The hydraulic circuit diagram of the ABS (anti-lock brake system) applied to the vehicle slope anti-rolling device of the present invention, as shown in Figure 1, by the operation of the vacuum booster (VB) by the pressure of the brake pedal (BP) brake And a master cylinder MC for generating pressure.

This master cylinder (MC) has two chambers (MCP, MCS), the first chamber (MCP) and front wheel right wheel to control the brake hydraulic pressure transmitted from the master cylinder (MC) to the wheel cylinder (WFR, WRL) Normally open inlet valves PC1 and PC2 are provided in the hydraulic line between the wheel cylinders WFR and WRL respectively installed at FR and rear wheel left wheel RL. Further, the brake fluid is provided with normal closed outlet valves PC5 and PC6 on the outlet side of the wheel cylinders WFR and WRL. The low pressure accumulator RS1 temporarily storing the brake fluid discharged from the wheel cylinders WFR, WRL and the brake fluid stored in the low pressure accumulator RS1 are forced to the outlet side of the normal closed outlet valves PC5 and PC6. A hydraulic pump HP1 and a motor M for reflux are provided.

On the other hand, in the hydraulic circuit of the front wheel left wheel FL and the rear wheel right wheel RR, the respective components are configured in the same way as the hydraulic circuit of the front wheel right wheel FR and the rear wheel left wheel RL. For reference, reference numerals WS1 to WS4 denote wheel speed sensors.

The normal open inlet valves PC1 to PC4 and the normal closed outlet valves PC5 to PC8, the motor M, and the hydraulic pumps HP1 and HP2 of FIG. 1 are operated by the electronic control unit ECU. do.

The anti-lock brake system having such a configuration, when the ABS control, to maintain the braking pressure provided to each wheel side, the normal open inlet valve (P1 ~ P4) is closed with the normal claw outlet valve (P5 ~ P8) closed In the case of opening the valve and reducing the braking pressure provided on each wheel side, the normal claw outlet valves P5 to P8 are opened. In addition, to increase the braking pressure on each wheel side, operate the motor M with the normal closed type outlet valves P5 to P8 closed and drive the hydraulic pumps HP1 and HP2. Open the valves P1 to P4.

As shown in FIG. 2, the vehicle skid prevention apparatus according to the embodiment of the present invention includes an electronic control unit (ECU) 10 that performs overall vehicle skid prevention control. The electronic control unit 10 consists of a main controller 11, an input interface 12 and an output interface 13.

The input interface 12 includes a brake pedal sensor 20, a master cylinder pressure sensor 21, a clutch sensor 23, a gear position sensor 23, a G sensor 24, a throttle position sensor 25 The engine torque sensor 26 and the wheel speed sensors WS1 to WS4 are electrically connected to each other. At this time, the G sensor 24 is a sensor for detecting the acceleration applied to the vehicle body, and is composed of a differential transformer, a control circuit, and the like. The core in the differential transformer is normally stopped at the center of the coil. However, when the acceleration / deceleration is applied to the vehicle body, the core moves and a voltage is generated according to the displacement amount of the core to detect the magnitude of the acceleration / deceleration. In the present invention, the voltage change according to the displacement amount of the core in the G sensor 24 is used to detect the inclination of the vehicle instead of the conventional acceleration detection. That is, when the vehicle is inclined, the core in the G sensor 24 is oriented to one side, and since the voltage change occurs differently according to the severity, the slope of the road surface is detected by detecting this.

In addition, the output interface 13 has a hydraulic pressure including various valves (normally open inlet valves P1 to P4 and normal claw outlet valves P5 to P8) and a valve for operating the motor M and a motor controller 30. The device is electrically connected.

On the other hand, the main controller 11 has a variety of information input through the input interface 12 (brake pedal detection value, master cylinder pressure value, clutch detection value, gear position value, G sensor value indicating the road slope as longitudinal acceleration, Based on the throttle valve position detection value and engine torque value), the vehicle is judged to stop at the slope of the vehicle, start after stopping, vehicle push and vehicle push, etc., and output the brake pressure to be appropriately adjusted for each wheel push. The hydraulic device is controlled via the interface 13.

Looking at the operation of the electronic control unit 10 with reference to Figure 3, first, the electronic control unit 10 determines whether the vehicle is stopped by the driver's braking on the inclined hill (S100), and maintains the control mode in the ready state Then, the moment the driver attempts to start the vehicle, the driver's acceleration will be recognized as the brake pedal release and clutch state, and it is determined whether the vehicle starts normally or is pushed in the direction opposite to the direction intended by the driver (S101). On the basis of the vehicle speed calculated from each wheel speed information detected by each wheel speed sensor, it is determined whether vehicle rolling occurs (S102), and when the vehicle rolling phenomenon occurs, the degree of pushing is determined by the vehicle speed and the road slope (the longitudinal direction). The rolling index (Roll_back_index) is calculated through the PD control using the acceleration value (S103, S104). At this time, the jungle index is calculated by the following equation (1).

Roll_back_index = V_ref × (P gain) + A_ref (D gain)

(Where Roll_back_index is the rolling index, V_ref is the vehicle speed, A_ref is the G sensor value, and D gain and P gain are constant values.)

Using this jungle index, the target pressure amount of the braking pressure amount to be provided to each wheel is determined (S105), and the pressure rise section and the maintenance section are determined during the control cycle, and the braking pressure is increased to the target pressure amount in the pressure rise section ( S106, S107), and the holding section maintains the braking pressure reaching the target pressure amount (S108). After such control, it is determined by the vehicle speed, the amount of engine torque, the opening amount of the engine intake that the vehicle starts stably without any further sliding phenomenon (S109), and releases the brake pressure that is currently maintained. By releasing the braking of the vehicle stably starts (S110).

That is, as shown in Figs. 4A, 4B, and 4C, the vehicle is traveling on a hill road, and when the driver determines that the vehicle is stopped by the brake pedal operation at time A, the control is ready. Wait in the state. At time B, since the driver releases the brake pedal to start the vehicle, the electronic control unit 10 monitors whether the vehicle starts normally or the vehicle push occurs. After that, when the jungle index calculated by the electronic control unit 10 starts to occur, the brake pressure control is started accordingly to prevent the vehicle from being pushed backward. The brake pressure control determines the braking pressure increase rate by determining the braking pressure increase amount and the holding amount according to the slide index, and controls the braking pressure increase rate by maintaining the pressure when a sufficient braking command is reached. At time C, the pressure is maintained to provide a limited time for the driver to accelerate, and at time D the vehicle pressure, engine torque, and throttle valve position are used to confirm that the vehicle starts stably and at the same time brake pressure. Release it.

As described above, the present invention has the effect of smoothly starting the vehicle while effectively preventing the vehicle by providing a variable amount of braking pressure appropriately according to the degree of sliding of the vehicle at the start after the vehicle stops at an incline.

Claims (3)

In the ramp slope prevention method of the vehicle for braking the vehicle by providing a braking pressure to each wheel, When the vehicle stops on the slope, it is judged whether or not a vehicle jungle has occurred. When vehicle rolling occurs, the target pressure amount corresponding to the vehicle rolling degree is determined, Preventing vehicle rolling by generating a determined target pressure amount. The method of claim 1, wherein the braking pressure is increased to reach the target braking pressure amount, and the target pressure amount is maintained after reaching the target pressure amount. 2. The method of claim 1, wherein the rolling degree of the vehicle is calculated from a vehicle speed and a road slope.

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