KR101131738B1 - Control method for electronics stability program in a vehicle - Google Patents

Abstract

The present invention relates to a control method of a vehicle attitude control device, and in particular, the present invention, if the handle is excessively manipulated momentarily, the operation of the ESP control is expected, by opening the valve means before the ESP control the hydraulic fluid to pump the brake fluid of the master cylinder After bypassing the engine, operate the hydraulic pump through the motor to raise the wheel pressure of each wheel cylinder to a predetermined level, and then close the normal-open inlet valve on each wheel cylinder to maintain the increased wheel pressure. Can increase the rate of increase more effectively to perform ESP control.

To this end, the present invention, if the handle is momentarily over-manipulated is expected to operate the vehicle attitude control, before opening the vehicle attitude control, opening the valve means for a certain time to increase the wheel pressure of each wheel cylinder by a predetermined level and Drive the motor together, close the valve means to maintain the increased wheel pressure on each wheel cylinder after a certain period of time, stop the motor, close the inlet valve, and start the vehicle attitude control after closing the inlet valve. It is characterized in that to start the vehicle attitude control by determining.

Description

CONTROL METHOD FOR ELECTRONICS STABILITY PROGRAM IN A VEHICLE}

1 is a simplified brake hydraulic circuit diagram of a general vehicle attitude control device.

2 is a brake hydraulic circuit diagram of a vehicle attitude control apparatus according to an embodiment of the present invention.

3 is a control flowchart illustrating a control method of the vehicle attitude control apparatus according to an embodiment of the present invention.

[Description of the Reference Numerals]

MC: Master cylinder SC1, SC2: Normally open cut valve

SI1, SI2: Valve means PC1-PC4: Normally open inlet valve

PC5-PC8: Normally closed outlet valve

MF: Main Hydraulic Pressure Line MFc: Auxiliary Hydraulic Pressure Line

10: electronic control unit (ECU) 11: steering angle sensor

12: yaw rate sensor 13: lateral acceleration sensor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method of an electronic vehicle stability program (ESP), and more particularly, to a control method of a vehicle attitude control device capable of effectively increasing wheel pressure during control of an ESP.

In general, the vehicle attitude control device is a vehicle attitude control (hereinafter referred to as ESP control), the vehicle's outer yaw rate during the vehicle turning under the oversteering conditions less than the driver's desired yaw rate estimated from the vehicle model The braking force is increased above the braking force of the inner wheel to generate a compensating moment (outward moment) acting outward of the vehicle, and under the condition of understeer where the actual yaw rate of the vehicle is greater than the driver's desired turning information, the braking force of the inner wheel of the vehicle is By generating a compensating moment (inward moment) that acts inwardly of the vehicle by increasing the braking force of the vehicle, the vehicle's driving safety is improved by controlling the actual yaw rate of the vehicle to maintain the desired yaw rate.

The vehicle attitude control device generates an outward moment by increasing the braking force of the front wheel turning outer wheel when the vehicle behavior is oversteer during ESP control, and increases the braking force of the inner wheel turning inner wheel when the understeering condition increases. By controlling the behavior of the vehicle.

As shown in FIG. 1, the vehicle attitude control apparatus includes a liquid pressure line MF connected between the master cylinder MC and the wheel cylinder W in the hydraulic modulator, and the suction side of the hydraulic pump HP. Auxiliary hydraulic pressure line (MFC) is connected between the master cylinder (MC). The hydraulic pump HP is operated by the motor M, which is driven by the electronic control unit ECU. The electronic control unit ECU drives the motor M to operate the hydraulic pump HP to control the brake fluid, thereby increasing the braking pressure of the wheel cylinder of the corresponding wheel.

The above ESP control is activated when the driver handles the handle badly in a sudden situation in which unexpected events occur suddenly while driving.

However, when ESP control is operated by excessively manipulating the steering wheel, the increase rate of wheel pressure is not relatively high at the beginning of ESP control due to the inertia of the motor which has been stopped and the brake caliper being far from the wheel. .

In addition, the wheel of the vehicle is subjected to an excessive lateral force in the ESP control operation by the excessive steering wheel operation compared to the normal driving conditions, it is difficult to increase the increase rate of the wheel pressure more than the normal driving conditions.

For this reason, there is a problem in that the initial ESP control cannot supply sufficient braking force so that the ESP control can not be effectively performed.

The present invention is to solve the above-mentioned problems, an object of the present invention is a vehicle attitude control device that can form a sufficient braking force by increasing the increase rate of the wheel pressure at the beginning of the ESP control even during the ESP control due to excessive handle operation momentarily It is to provide a control method of.

The control method of the vehicle attitude control apparatus of the present invention for achieving the above object is a master cylinder, a hydraulic pump for pumping the brake fluid to reflux to each wheel cylinder side, a motor for driving the hydraulic pump, and each wheel cylinder And a valve means installed in an auxiliary hydraulic line provided so that the brake fluid of the master cylinder can be directly bypassed by the hydraulic pump. In the control method of the vehicle attitude control device for adjusting the braking force for each wheel, when the handle is excessively manipulated momentarily and the operation of the vehicle attitude control is expected, the wheel pressure of each wheel cylinder before the vehicle attitude control starts. When opening the valve means for a predetermined time to increase the predetermined level to drive the motor After the predetermined time has elapsed, the valve means is closed to maintain the increased wheel pressure on each wheel cylinder, the motor is stopped, the inlet valve is closed, and the vehicle attitude control is started after the inlet valve is closed. Determine and start the vehicle attitude control.

The vehicle attitude control is characterized in that it is determined that the operation of the vehicle attitude control is expected if the vehicle speed is a predetermined speed or more and the steering angle speed is a predetermined value or more so that the operation of the vehicle attitude control within a predetermined time is expected.

And drive the motor such that the motor is rotated at a low speed to overcome the stop inertia.

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

2 is a brake hydraulic circuit diagram of a vehicle attitude control apparatus according to an embodiment of the present invention. As shown in FIG. 2, the master cylinder MC is configured to generate the brake pressure by the operation of the vacuum booster VB by the pressing of the brake pedal BP.

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) A normal open cut valve SC1 is provided in the liquid pressure line MF between the wheel cylinders WFR and WRL provided at the FR and the rear wheel left wheel RL, respectively. In addition, the normal open inlet valves PC1 and PC2 are provided in the hydraulic lines MFr and MFl between the normal open cut valve SC1 and the wheel cylinders WFR and WRL. These normal open inlet valves PC1 and PC2 are provided with check valves CV1 and CV2 in parallel, respectively. The brake fluid in the wheel cylinders WFR and WRL is returned to the master cylinder MC through the cut valves SC1 via the check valves CV1 and CV2.

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 for temporarily storing the brake fluid discharged from the wheel cylinders WFR and WRL and the brake fluid stored in the low pressure accumulator RS1 are pumped to the outlet side of the normal closed outlet valves PC5 and PC6. A hydraulic pump HP1 forcibly refluxing to the wheel cylinder side and a motor M for driving the inflow pump HP1 are provided.

On the other hand, a valve means SI1 of a normal closed type is provided between the suction side of the hydraulic pump HP1 and the auxiliary hydraulic line MFc between the first chamber MCP of the master cylinder MC. The check valves CV5 and CV6 are respectively provided on two hydraulic lines branched by the auxiliary hydraulic line MFc. Accordingly, when the valve means SI1 is closed, the auxiliary hydraulic line MFc between the master cylinder MC and the hydraulic pump HP1 is shut off, and when the valve means SI1 are opened, the master cylinder MC and the hydraulic pump are closed. Auxiliary hydraulic pressure line MFc between HP1 is connected. At this time, the check valve CV5 prevents the brake fluid from flowing into the low pressure accumulator RS1.

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 DP1 and DP2 are high pressure accumulators.

2, the inlet valves PC1-PC4 and the outlet valves PC5-PC8 in the cut valves SC1 and SC2, the inlet valves SI1 and SI2, and the wheel cylinders WFR, WRL, WFL, and WRR; The motor M for operating the hydraulic pumps HP1 and HP2 is operated by an electronic control unit (ECU) 10 which performs a control mode such as ESP mode.

The wheel speed sensors WS1-WS4 provided at the front left and right wheels FL and FR and the rear left and right wheels RL and RR are electrically connected to the ECU 10 so as to provide the detected speed of the wheels. Is connected.

In addition, the electronic control unit 10 is provided on the steering shaft of the steering wheel and the steering angle sensor 11 for detecting the steering angle and the steering angle speed according to the steering wheel operation of the driver, yaw rate sensor 12 for detecting the yaw rate of the vehicle and The lateral acceleration sensor 13 which detects lateral acceleration of the vehicle is electrically connected.

The electronic control unit 10 obtains vehicle speed information from each wheel speed sensor WS1-WS4, obtains steering angle and steering angle speed information from the steering angle sensor 11, and yaw rate from the yaw rate sensor 12. The information is obtained, the lateral acceleration information is obtained from the lateral acceleration sensor 13, and the ESP control is performed using the respective pieces of information.

In addition, the electronic control unit 10 calculates the yaw rate deviation between the yaw rate desired by the driver estimated from the vehicle model and the actual yaw rate detected by the yaw rate sensor 12, and the calculated yaw rate amount. ESP control is performed from the deviation.

The electronic control unit 10 determines whether the vehicle behavior is oversteer or understeer from the yaw rate deviation during the ESP control, and if the vehicle behavior is oversteer, the hydraulic pump HP1 through the motor M. Or by operating the HP2) to increase the braking force of certain wheels and, if the vehicle behavior is understeer, stabilize the vehicle behavior by increasing the braking force of other specific wheels by operating the hydraulic pump (HP1 or HP2) through the motor (M). .

At this time, as described above, when the driver excessively operates the handle to operate the ESP control, the increase rate of the wheel pressure at the initial stage of the ESP control is caused by the inertia of the motor which is initially stopped and the effect that the brake caliper is far from the wheel. Because this is not relatively high, effective ESP control may not be performed.

In order to prevent this, in the present invention, the steering angular velocity is used to detect whether the steering wheel is excessively manipulated momentarily before the ESP control is started, and the operation of the ESP control is expected, and when the operation of the ESP control is expected, the ESP control is started. Before opening the valve means (SI1, SI2) for a predetermined time while operating the hydraulic pump (HP1, HP2) through the motor (M). Accordingly, the brake fluid of the master cylinder MC is bypassed directly to the hydraulic pump HP suction side, and the bypassed brake fluid is pumped to increase the wheel pressure of each wheel cylinder. After a certain time, the valve means (SI1, SI2) are closed and the motor (M) is stopped to maintain the increased wheel pressure on each wheel cylinder. PC4) is closed. Then, by determining whether it is the ESP control start time and starting the ESP control, it is possible to relatively increase the increase rate of the wheel pressure at the beginning of the ESP control.

Hereinafter, the control method of the vehicle attitude control apparatus of the present invention for further improving the increase rate of the wheel pressure at the beginning of the ESP control in the present invention will be described in more detail.

Referring to FIG. 3, first, in steps S100 and S101, the electronic control unit 10 detects each wheel speed from each wheel speed sensor WS1-WS4, and calculates a vehicle speed using each detected wheel speed.

At the same time, the electronic control unit 10 detects the steering angular velocity in step S102.

Then, in step S103, the electronic control unit 10 determines whether the calculated vehicle speed is equal to or greater than a preset speed in order to determine whether the vehicle is traveling at a predetermined speed.

When the vehicle speed travels above the preset speed, in step S104 and step S105, the electronic control unit 10 detects that the steering angle speed detected by the driver is excessively manipulated by the driver to determine whether the operation of the EPS control is expected. It is determined whether or not the preset value is within a predetermined time.

If the driver turns the steering wheel excessively momentarily and the detected steering angle speed is higher than or equal to the preset speed, the electronic control unit 10 anticipates that the ESP control will be activated soon in step S106 to step S108 so that the ESP control is started. The motor M is driven at a low speed so as to open the valve means SI1 and SI2 for a predetermined time so that the wheel pressure of each wheel cylinder is increased to a predetermined level while the motor M is rotated to overcome the stop inertia. Accordingly, the brake fluid of the master cylinder MC flows into the suction side of the hydraulic pump HP and is pumped into each wheel cylinder, thereby gradually increasing the wheel pressure of each wheel cylinder. At this time, since before the ESP control, the rotation speed of the motor M is adjusted to a low speed so that the finally increased wheel pressure value is very low compared with the pressure value for the purpose of braking.

At this time, the motor M is rotated at a low speed to overcome the stop inertia.

After a certain time, the electronic control unit 10 first closes the valve means SI1 and SI2 and stops the motor M in step S109 so that the increased wheel pressure is maintained in each wheel cylinder. In addition, in step S110, the normal open inlet valves PC1-PC4 provided at the inlet of each wheel cylinder are closed.

Then, in step S111, the electronic control unit 10 determines whether the ESP control starts at the start point using the yaw rate deviation as described above, and if it is determined that the start point of the ESP control starts, at step S112, the ESP control Initiate. At this time, since the motor is driven at a low speed, and further, each wheel pressure is increased to a predetermined level or more, when the braking force of the wheel is increased at the initial stage of the ESP control, the increase rate of the wheel pressure can be further improved. Can be effectively controlled to improve the stability of the vehicle behavior.

As described in detail above, in the present invention, when the handle is momentarily over-managed and the operation of the ESP control is expected, the valve means is opened before the ESP control to bypass the brake fluid of the master cylinder to the hydraulic pump suction side, and then the motor is operated. The hydraulic pump is operated to raise the wheel pressure of each wheel cylinder to a predetermined level, and then the normal open inlet valve on each wheel cylinder is closed to maintain the increased wheel pressure. Thus, the increase rate of the wheel pressure in the early stage of ESP control can be improved. There is an effect that can effectively perform the ESP control.

Claims (3)

A master cylinder, a hydraulic pump for pumping brake fluid to return to each wheel cylinder, a motor for driving the hydraulic pump, a normal open inlet valve provided at the inlet of each wheel cylinder, and a normal closed outlet valve provided at the outlet And a valve means installed in an auxiliary hydraulic line provided so that the brake fluid of the master cylinder is directly bypassed to the hydraulic pump, and in a vehicle posture control method, a control method of a vehicle posture control device for adjusting a braking force for each wheel. In If the vehicle speed is above a certain speed and the steering angle speed of the steering wheel reaches a preset value such that vehicle attitude control is required, a predetermined time is increased to increase the wheel pressure of each wheel cylinder before starting the vehicle attitude control. While driving the motor while opening the valve means, Closing the valve means so as to maintain the increased wheel pressure on each wheel cylinder after the predetermined time has elapsed, stopping the motor and closing the inlet valve, And determining the vehicle attitude control start time after the inlet valve is closed to start the vehicle attitude control. delete The method of claim 1, wherein the driving of the motor, And the motor rotates at a low speed enough to overcome the stop inertia.

Images