KR100751249B1 - Non driving wheel ABS control method of vehicle - Google Patents

Abstract

The present invention relates to a method for controlling a driven wheel ABS of a vehicle, the first step of determining whether the braking force compensation control condition to compensate for the braking force loss due to the difference in the slip ratio of the two wheels of the driven wheel, and the braking force compensation control result A second step of comparing which of the two wheels of the driven wheel has a small slip ratio if the condition is determined to be a condition; and for the wheel having a large slip ratio as a result of the determination, the brake hydraulic pressure is controlled according to the behavior of the wheel, This small wheel is provided with a third step of controlling brake hydraulic pressure by means of a hydraulic vehicle applied to both the wheel's behavior and / or both wheels of the driven wheel to compensate for the braking force, thereby ensuring the safety of the vehicle. By utilizing the frictional force of each wheel to the maximum, braking performance and safety can be secured on all roads during sudden braking.

Description

Non driving wheel ABS control method of vehicle

1 is a schematic configuration diagram for explaining a general ABS.

2 is a general ABS hydraulic circuit diagram

3 is a view showing an example of a general ABS control pattern.

4A and 4B are control flowcharts of a method for controlling a driven wheel ABS of a vehicle according to an exemplary embodiment of the present invention.

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

10: electronic control device 20: wheel speed detection unit

30: braking detection unit 30a: brake pedal

40: hydraulic control means 50: hydraulic module

51: master cylinder 52: normal open solenoid valve

53: Normally closed solenoid valve 54: Hydraulic pump

55: motor

The present invention relates to a method of controlling a driven wheel ABS for a vehicle, in order to ensure the stability as well as braking of the vehicle during braking of the vehicle, wheels in which a large slip occurs during ABS control of the driven wheel are controlled according to the behavior of the wheel. At the same time, the opposite wheel is controlled by the movement of the wheel and / or the hydraulic pressure difference applied to both wheels of the driven wheel, so that the driving wheel ABS control method of the vehicle can maximize the braking performance and safety of the vehicle. It is about.

In general, automobiles are equipped with a brake system for stopping and speed control, and recently, an anti-lock brake system (hereinafter referred to as an anti-lock brake system) is used to improve the braking ability of the vehicle and to secure steering stability during braking. ABS is called).

ABS prevents the phenomenon by detecting the wheels during braking in advance to prevent the vehicle from slipping due to the failure to transfer the braking force to the road surface when braking during high-speed driving on roads with low braking friction coefficient. It is a system for doing so.

1 is a view showing a schematic configuration for explaining a general ABS.

As shown in FIG. 1, the electronic controller 10 analyzes the current wheel speeds transmitted from the wheel speed detector 20 and the current braking values transmitted from the brake detector 30 to determine the current driving situation. Generate the appropriate ABS control value. The hydraulic control means 40 controls the hydraulic module 50 in accordance with the ABS control value. That is, the electronic control apparatus 10 estimates the vehicle speed by using the wheel rotation speed detection sensor installed in the front and rear wheels of the vehicle during braking, and based on the deceleration and {(body speed-wheel speed) / body speed} × 100 ( %)} Estimates the current slip rate. The electronic control apparatus 10 predicts the occurrence of the fixed state of the vehicle by using the estimated data described above as an input variable, and closes the wheel speed to the vehicle body speed by reducing the brake pressure using the hydraulic control means 40 before. . Then, a series of operations of braking the wheels by increasing the brake pressure before the speed of the wheel exceeds a certain value is repeated to control to maintain the slip ratio of the braking vehicle in a desirable state.

2 is a view showing a general ABS hydraulic circuit diagram.

As shown in Fig. 2, the braking hydraulic pressure is formed in the master cylinder 51 by the operation of the brake pedal 30a by the driver, and the braking hydraulic pressure is the inlet of the front wheels FL, FR and the rear wheels RL, RR. It is transmitted to the front and rear wheel cylinders FL, FR, RL, RR by a normal open solenoid valve (NO) 52 provided on the side and a normal closed solenoid valve (NC) 53 provided on the outlet side. In addition, a pair of hydraulic pumps 54 are connected to the low pressure accumulator LPA in which oil discharged from the wheel cylinder side is temporarily stored, and the hydraulic pump 54 is driven by the motor 55 to operate the low pressure accumulator LPA. The oil stored in the pump is delivered to the high pressure accumulator (HPA). The high pressure accumulator (HPA) attenuates pressure pulsations due to the operation of the pump 54. In this way, the braking pressure is transmitted to the wheel cylinder, and the braking force is exerted. At this time, if the friction with the road surface is insufficient, causing excessive slip ratio, wheel locking occurs, and the ABS control unit opens the solenoid valve NO at the inlet of the wheel cylinder. Close and open outlet solenoid valve (NC) to depressurize, then close both inlet and outlet solenoid valves (NO) (NC) to maintain braking pressure, then open inlet solenoid valve (NO) and open outlet solenoid ABS control operation is performed to close and boost the valve NC. The ABS control operation keeps the slip ratio in a certain range during braking and prevents locking of the wheels, so that sufficient frictional force is transmitted to the road surface and the braking distance can be shortened.

On the other hand, the hydraulic control as described above is usually performed independently of each of the driving wheel and the driven wheel, but in the case of the driven wheel, since the driving wheel is directly connected to the safety problem of the vehicle in general, the driving wheel is independently controlled, and the driven wheel is generally used. In the case of brake braking, the reduction ratio of left and right wheels is compared and the hydraulic pressure of left and right wheels is simultaneously controlled according to the wheel that slips first (4-sensor 3-channel method), and the solenoid valve is arranged on the left and right of the rear wheels. At the same time, when one slip occurs, the method of reducing the frictional side at the same time to prevent the rear wheel from locking the frictional side and evenly distributes the brake pressure (four-sensor four-channel system) is commonly used.

However, according to the conventional method of controlling the driven wheel as described above, the safety of the vehicle can be secured considerably, but the braking distance is long. That is, the driven wheel ABS control of the conventional vehicle is a problem that unnecessary loss of braking force is generated by emphasizing safety more than necessary by controlling the wheels having a relatively low slip rate at the same pressure based on the wheels showing the high slip rate among the driven wheels. There was.

Accordingly, the present invention has been made to solve the problems described above, the wheel that the slip occurs largely during the ABS control of the driven wheel in order to ensure not only the safety of the vehicle but also the braking property during the sudden braking of the vehicle is dependent on the behavior of the wheel In accordance with the control, the wheel on the opposite side is controlled by the movement of the wheel and / or the pressure difference of the hydraulic pressure applied to both wheels of the driven wheel, thereby ensuring the maximum braking performance and safety of the vehicle. An object of the present invention is to provide a driving method of driving ABS.

In accordance with an aspect of the present invention, there is provided a method for controlling a driven wheel ABS of a vehicle, including: a first step of determining whether a braking force compensation control condition is performed to compensate for braking force loss due to a difference in slip ratio between two wheels of a driven wheel; If it is determined that the braking force compensation control condition is determined, the second step of comparing which of the two wheels of the driven wheel has a small slip ratio, and as a result of the determination, for the wheel having a large slip ratio, And a third step of controlling the brake hydraulic pressure by the hydraulic vehicle applied to both the wheel's behavior and / or both wheels for the braking force compensation for the wheel with a small slip ratio.

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

3 is a diagram illustrating an example of a general ABS control pattern.                     

Referring to FIG. 3 with reference to FIGS. 1 and 2, first, the electronic control apparatus 10 calculates the speed, acceleration / deceleration speed, and estimated body speed of each wheel based on a signal input from each wheel speed sensor 20. . When the brake hydraulic pressure is transmitted to each wheel cylinder by stepping on the brake pedal 30a, each wheel speed starts to fall. If either wheel is about to be locked, i.e. if the speed of the wheel is lower than the preset reference wheel speed for control, the electronic control device sends a "keep" signal to the solenoid valve of the corresponding wheel, followed by a "decompression". Send a signal to loosen the wheel cylinder hydraulic pressure.

The decompression time is determined by the program of the electronic controller at the rotational deceleration degree of the wheel (area A). Thereafter, the solenoid valve is placed in the " hold " state and the electronic control device then continues to monitor the recovery state of the wheel rotation by the wheel speed and the wheel acceleration / deceleration. If the recovery of the wheel rotation speed is too fast, fine control of "pressing" and "holding" is repeated (area B). When the wheel tries to enter the lock area again, a "decompression" signal is issued to adjust the hydraulic pressure (area C), and control of pressurization and depressurization is repeated to reach a stop.

4A and 4B are control flowcharts of a method for controlling a driven wheel ABS of a vehicle according to an exemplary embodiment of the present invention.

As shown in FIGS. 4A and 4B, the method for controlling the driven wheel ABS of the vehicle according to the present invention is largely determined to determine whether it is a braking force compensation control condition for compensating a braking force loss due to a difference in slip ratio between two wheels of the driven wheel. Step 1 and the second step of comparing and determining which of the two wheels of the driven wheel has a small slip ratio when it is determined that the braking force compensation control condition is determined, and the wheel behavior of the wheel having the large slip ratio as a result of the determination. And a third step of controlling the brake hydraulic pressure by the hydraulic vehicle applied to both the wheel of the driven wheel and / or both wheels of the driven wheel to compensate the braking force for the wheel having a small slip ratio. have.

Referring to the first step with reference to the drawings, first, when the driver brakes by operating the brake pedal while the vehicle is running, the electronic control device uses the signal input from each wheel speed detection unit, the speed and deceleration of each wheel Calculate speed, estimated body speed and slip rate. At this time, when the calculated wheel speed and deceleration exceeds the preset threshold value for the driven wheel that does not transmit the driving force, the electronic control device regards it as rapid braking and determines that braking force compensation control is necessary. When the threshold value is not exceeded, the following control is performed to control the wheel having a relatively low slip ratio at the same pressure, based on the wheel having a high slip ratio as in the prior art. This is because the braking force is secured to some extent even if the braking force is not compensated because it is not a sudden braking.

On the other hand, with respect to the drive wheels that generate the driving force, the electronic control device independently controls the brake hydraulic pressure on the left and right wheels using hydraulic control means using the calculated information.

Referring to the drawing, the second step will be described. When the braking force compensation control condition is satisfied in the first step, the electronic controller compares the calculated slip ratios of the left and right wheels of the driven wheel with each other to slip the freezing wheel. Determine if the rate is smaller. This is because, in order to compensate for the braking force while maintaining safety during sudden braking, it is necessary to control the smaller slip ratio while watching the wheel behavior of the larger slip ratio.

Referring to the third step with reference to the drawings,

As a result of the determination of the second step, the wheel having the larger slip ratio among the two wheels is independently controlled like the driving wheel control. That is, the electronic control device determines that the locking of the wheel has not yet occurred if the current slip ratio calculated for the wheel with the larger slip ratio does not reach a preset slip ratio for control. To increase the hydraulic pressure. However, when the current slip ratio exceeds the set slip ratio, that is, when locking is to occur on the wheel, the hydraulic pressure is reduced in consideration of wheel acceleration, and the holding, pressing, and holding are repeated according to the wheel recovery trend. Control to reach a stop.

As a result of the determination of the second step, the wheel with the smallest slip ratio of both wheels has a predetermined slip ratio range (minimum slip ratio to maximum slip) in order to compensate for braking force loss within a range where stability of the vehicle is ensured during braking. And the slip ratio calculated by the electronic control device when the current slip ratio for the one with the smaller slip ratio falls within the slip ratio range, the safety of the vehicle is guaranteed even if the hydraulic pressure is not reduced. It maintains brake hydraulic pressure applied to it. In addition, even when the current slip ratio is outside the preset maximum slip ratio, when the hydraulic vehicle applied to both wheels of the driven wheel is smaller than the predetermined predetermined value, the safety of the vehicle is guaranteed as described above. Maintain the hydraulic pressure applied. By doing this, it is possible to reduce the loss in terms of braking distance as compared with the method of unconditionally following the hydraulic pressure applied to the wheel with the large slip ratio and reducing the hydraulic pressure of the wheel with the small slip ratio.

On the other hand, when the current slip ratio for the wheel with the smaller slip ratio is smaller than the preset minimum slip ratio, and the current slip ratio is greater than the preset maximum slip ratio, the hydraulic pressure applied to both wheels exceeds the preset predetermined value. In order to ensure the safety of the vehicle, the hydraulic pressure applied to the wheel with the large slip ratio is reduced by following the hydraulic pressure applied to the wheel with the large slip ratio.

As described above, according to the method for controlling the driven wheel ABS of the vehicle according to the present invention, by controlling the driven wheel ABS appropriately and using the maximum frictional force of each wheel, it is possible to ensure braking performance and safety on all road surfaces during sudden braking. .

Claims (4)

In the ABS control method of the vehicle, A first step of determining whether the braking force compensation control condition is used to compensate for braking force loss due to a difference in slip ratio between the two wheels of the driven wheel; If it is determined that the braking force compensation control condition is determined, comparing and determining which of the two wheels of the driven wheel has a small slip ratio; As a result of the determination, the brake hydraulic pressure is controlled according to the wheel behavior for the wheel with a large slip ratio, and the hydraulic vehicle applied to both wheels of the driven wheel and / or the driven wheel to compensate for braking force for the wheel with a small slip ratio. And a third step of controlling the brake hydraulic pressure by means of the driven wheel ABS control method of the vehicle. The method of claim 1, Satisfying the braking force compensation control condition of the first step, And a wheel speed and a deceleration of each of the driven wheels are greater than a predetermined threshold value. The method of claim 1, In the third step, when the wheel having the small slip ratio is controlled in consideration of the wheel's behavior, When the current slip rate is located in the preset slip rate section, the hydraulic pressure is maintained for compensation of braking force, and when the current slip rate is out of the set slip rate section, the oil pressure is reduced to ensure safety. How to control driven wheel ABS of vehicle. The method of claim 1, In the third step, when the wheel having the small slip ratio is controlled in consideration of the wheel movement and the hydraulic vehicle applied to the driven wheel, Even if the current slip ratio is greater than the set maximum slip ratio, the hydraulic pressure is maintained to compensate for braking force when the hydraulic vehicle with the opposite wheel is less than the preset reference value, and the hydraulic pressure is guaranteed to ensure safety when the hydraulic vehicle is larger than the preset reference value. Follower wheel ABS control method of a vehicle, characterized in that for reducing.

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