KR20170023645A - Rear wheel emb combi brake system control method - Google Patents

Abstract

The present invention comprises: a step of enabling a control unit to compare deceleration with a reference value of the preset deceleration to determine whether or not the deceleration is not larger than the reference value of the deceleration in case of braking; and a step of enabling the control unit to restrain a braking force of a front wheel hydraulic braking system until the deceleration reaches the reference value of the deceleration in accordance with a result of determination.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a rear wheel EMBROM brake control system,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a control method for a rear wheel EMB combination brake system, and more particularly, to a rear wheel EMB combination brake system in which a braking force of a front wheel hydraulic braking system is suppressed according to a deceleration rate during braking, To a control method of the control unit.

Generally, there are EHB (Electro Hydraulic Brake) system, hydraulic booster system, electric booster system and EMB (Electro Mechanical Brake) system which can regenerate braking coordination control.

Particularly, the EMB system generates the braking force of each wheel, and is very suitable for varying the braking distribution of the front wheel and the rear wheel.

Accordingly, the EMB system may be applied to all four wheels, or only the rear wheel EMB system may be used, and the front wheels may be applied to a rear wheel EMB combination brake system using a conventional hydraulic braking system.

However, since the conventional rear wheel EMB combination brake system does not perform active control for the front wheel braking force, it is difficult to maximize the regenerative braking efficiency because the battery charging by the regenerative braking must be performed only within the range of the rear wheel braking force.

The background art of the present invention is disclosed in Korean Patent Laid-Open Publication No. 10-2015-0031582 (Feb. 25, 2015) entitled " EMB Parking Braking System Using Hydraulic Device and Control Method Thereof ".

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rear-wheel EMB combination brake system which improves regenerative braking efficiency through a rear wheel EMB system by suppressing a braking force of a front wheel hydraulic braking system in accordance with a deceleration rate during braking, And to provide a control method thereof.

Another object of the present invention is to provide a control method of a rear wheel EMB combination brake system capable of increasing the amount of regenerative braking to improve fuel economy and reduce the amount of carbon dioxide generated.

The control method of a rear wheel EMB combination brake system according to an aspect of the present invention includes the steps of: determining whether the depressing speed is below the depressing speed reference value by comparing a depressing speed with a predetermined depreciation speed reference value during braking; And controlling the braking force of the front wheel hydraulic braking system until the depression rate reaches the depression rate reference value in accordance with the determination result.

In the step of suppressing the braking force of the front wheel hydraulic braking system of the present invention, the control unit cuts off the wheel pressure supplied to the front wheel from the master cylinder of the hydraulic circuit.

In the present invention, the control unit generates the braking force of the front wheel hydraulic braking system when the depressing speed exceeds the reference value of the depreciation rate.

In the present invention, the depreciation rate reference value is a depreciation rate that is expected to cause no rear wheel lock when generating only the braking force of the rear wheel EMB system.

According to another aspect of the present invention, there is provided a control method of a rear wheel EMB combination brake system, comprising: determining whether a control unit satisfies a predetermined quick braking condition; And selectively controlling the braking force of the front wheel hydraulic braking system according to whether or not the quick braking condition is satisfied as a result of the determination.

The controller determines that the rapid braking condition is satisfied when the braking demand change rate is equal to or greater than a predetermined braking demand change rate reference value.

In the step of selectively suppressing the braking force of the front wheel hydraulic braking system, the control unit suppresses the braking force of the front wheel hydraulic braking system if the control unit does not satisfy the rapid braking condition.

According to the present invention, the control unit suppresses the braking force of the front wheel hydraulic braking system when the depreciation rate is less than a preset depreciation rate reference value.

In the present invention, the control unit cuts off the wheel pressure supplied to the front wheel from the master cylinder of the hydraulic circuit, thereby suppressing the braking force of the front wheel hydraulic braking system.

In the present invention, the control unit generates the braking force of the front wheel hydraulic braking system when the depressing speed is equal to or greater than the reference value of the depreciation rate.

In the present invention, the depreciation rate reference value is a depreciation rate that is expected to cause no rear wheel lock when generating only the braking force of the rear wheel EMB system.

In the present invention, in the step of selectively suppressing the braking force of the front wheel hydraulic braking system, the control unit generates braking force of the front wheel hydraulic braking system when the control unit satisfies the rapid braking condition.

In the present invention, the control unit increases the braking force of the rear wheel EMB system relatively more than the braking force of the rear wheel EMB system when the sudden braking condition is not satisfied.

The present invention suppresses the braking force of the front wheel hydraulic braking system in accordance with the depreciation rate during braking, thereby increasing the amount of regenerative braking to improve fuel economy and reduce the amount of generated carbon dioxide.

1 is a block diagram of a control apparatus of a rear wheel EMB combination brake system according to an embodiment of the present invention.
2 is a view showing a state in which an outlet valve is opened in a hydraulic circuit diagram of a rear wheel EMB combination brake system according to an embodiment of the present invention.
3 is a diagram showing a state in which an outlet valve is closed in a hydraulic circuit diagram of a rear wheel EMB combination brake system according to an embodiment of the present invention.
4 is a flowchart showing an example of a control method of the rear wheel EMB combination brake system according to the first embodiment of the present invention.
5 is a graph showing changes in braking force of the rear wheel EMB combination brake system according to the first embodiment of the present invention.
6 is a flowchart showing a control method of the rear wheel EMB combination brake system according to the second embodiment of the present invention.
7 is a graph showing changes in braking force of the rear wheel EMB combination brake system according to the second embodiment of the present invention.

Hereinafter, a control method of a rear wheel EMB combination brake system according to an embodiment of the present invention will be described in detail with reference to 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. Further, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the user, the intention or custom of the operator. Therefore, definitions of these terms should be made based on the contents throughout this specification.

FIG. 1 is a block diagram of a control apparatus of a rear wheel EMB combination brake system according to an embodiment of the present invention. FIG. 2 is a diagram showing a hydraulic circuit diagram of a rear wheel EMB combination brake system according to an embodiment of the present invention. And FIG. 3 is a view showing a state in which an outlet valve is closed in a hydraulic circuit diagram of a rear-wheel EMB combination brake system according to an embodiment of the present invention.

1 to 3, in an EMB (Electromechanical Brake) combination braking system according to an embodiment of the present invention, the controller 10 controls a hydraulic circuit of a rear wheel EMB combination brake system to control the rear wheel EMB combination brake system Thereby improving the regenerative braking efficiency.

In the present embodiment, the hydraulic braking system is applied to the front wheel and the EMB system is applied to the rear wheel of the rear wheel EMB combination brake system. Since the rear wheel braking is performed in the EMB system, the hydraulic circuit for braking the rear wheel in the rear wheel EMB combination brake system is unnecessary.

2 and 3, the hydraulic circuit includes a TCV (Traction Control Valve) 20, a HSV (High Pressure Switch Valve) 30, an inlet valve 40, an outlet valve 50, And an accumulator 60 are provided.

The master cylinder 80 converts the operation of the brake pedal 70 into hydraulic pressure and supplies it.

The TCV 20 supplies the flow rate supplied from the master cylinder 80 to the front wheel.

The inlet valve 40 controls the hydraulic pressure supplied to the front wheel from the hydraulic pump and the TCV 30 to form the wheel pressure through the front wheel. The outlet valve 50 controls the hydraulic pressure discharged from the front wheel, The amount of brake fluid delivered from the master cylinder 80 to the front wheel is transmitted to the accumulator 60 without being transmitted by the wheel pressure.

The accumulator 60 is installed on the outlet-side flow path of the outlet valve 50, and supplies the hydraulic pressure to the accumulator 60 via the hydraulic pump. In addition, the accumulator 60 stores the hydraulic pressure supplied through the outlet valve 50.

The control unit 10 controls the opening and closing of the TCV 20, the HSV 30, the inlet valve 40 and the outlet valve 50 to control the operation of the hydraulic circuit.

In particular, when the braking condition is satisfied, the controller 10 compares the depreciation rate with a predetermined depreciation rate reference value to determine whether the depreciation rate has reached the depreciation rate reference value, and when the depreciation rate reaches the depreciation rate reference value The braking force of the front wheel hydraulic braking system is suppressed. In this case, as shown in FIG. 2, the control unit 10 opens the outlet valve 50 to consume the amount of the brake fluid delivered from the master cylinder 80 to the front wheel wheel to the accumulator 60 without delivering the wheel pressure to the rear wheel EMB system Thereby increasing the amount of regenerative braking.

Here, the braking condition includes not only whether or not the driver directly depresses the pedal, but also the brake pedal 70, that is, the driver's brake pedal response force such as ESC (Electronic Stability Control), TCS (Traction Control System), VDC A predetermined braking condition in a system that is operated without.

Also, the depreciation rate reference value is a depreciation rate that is expected to prevent the rear wheel lock from occurring when only the braking force of the rear wheel EMB system is generated. The rear-wheel regenerative braking force without the front wheel braking force can not exceed the deceleration speed reference value. This is because the rear wheel lock may occur in the low friction road. The reference value of the depreciation rate can be set variously according to the vehicle specification, but 0.15 g may be adopted as an example.

Therefore, if the depression rate is less than 0.15 g, the control unit 10 opens the outlet valve 50 to consume the amount of the brake fluid delivered from the master cylinder 80 to the front wheels to the accumulator 60 Thereby suppressing the braking force of the front wheel hydraulic braking system and thereby improving the regenerative braking amount by the rear wheel EMB system.

Then, when the depression rate is higher than the depreciation rate reference value, the controller 10 closes the outlet valve 50 as shown in FIG. 3 to generate the braking force in the front wheel hydraulic braking system. That is, the control unit 10 closes the outlet valve 50 and supplies the hydraulic pressure supplied from the master cylinder 80 to the front wheel.

On the other hand, when the braking condition satisfies the rapid braking condition, the control unit 10 closes the outlet valve 50, thereby maximizing braking responsiveness. Since most of the brakes are less than 0.3 g, the regenerative braking is not performed at the same time as the braking, and the control of the outlet valve 50 does not affect the overall fuel economy. Furthermore, since it is a dangerous situation at the time of sudden braking, it is very important to improve the braking responsiveness.

Accordingly, the control unit 10 generates the braking force of the front wheel hydraulic braking system, and controls the rear wheel EMB system in response to the sudden braking response. That is, the control unit 10 generates the braking force of the front wheel hydraulic braking system, and increases the braking force of the rear wheel EMB system relatively larger than the braking force when the sudden braking condition is not satisfied.

In the rear wheel EMB combination braking system in this embodiment, the front wheel hydraulic braking system has no required amount of fluid consumed on the rear wheel side compared with the conventional hydraulic braking system, and the response slope thereof is larger than that of the conventional braking hydraulic system. That is, the front wheel hydraulic braking system of the rear wheel EMB combination brake system has quicker response than the conventional braking hydraulic system. Therefore, the rear wheel EMB combination brake system can increase the responsiveness in the case of rapid braking.

The front hydraulic braking system is superior to the conventional hydraulic braking system. Therefore, even if the front wheel braking is not performed by the interval in which the depreciation speed reaches the depreciable speed reference value, as in the case of the above-described regenerative braking, the front hydraulic braking system has a response time until the braking force of about 1 g is generated, . ≪ / RTI >

Accordingly, the rear wheel driving force control of the rear wheel EMB system can be performed at the speed of the conventional hydraulic braking system. However, since the front wheel hydraulic braking system does not perform the braking force as long as the deceleration speed reference value interval , The braking force of the rear wheel EMB system is increased to be relatively larger than the braking force of the existing hydraulic braking system in the case where the rapid braking condition is not satisfied, and the rear wheel EMB system is controlled to have quick braking response.

For reference, the rapid braking condition is determined based on whether or not the braking demand change rate is equal to or greater than a preset braking demand change amount reference value. The change rate of the braking demand can be expressed by (d2-d1) / (t2-t1) as a rate of change with respect to time of the braking demand d2 at time t1 and the braking demand d2 at time t2. Indicating relatively large changes. A large braking demand change rate means that the driver steps on the pedal quickly. The change rate of the braking demand can be used as a criterion to judge the rapid braking and the complete braking.

Hereinafter, a control method of a rear wheel EMB combination brake system according to an embodiment of the present invention will be described in detail with reference to FIG. 4 to FIG.

FIG. 4 is a flowchart showing an example of a control method of the rear wheel EMB combination brake system according to the first embodiment of the present invention, and FIG. 5 is a flowchart illustrating a control method of the rear wheel EMB combination brake system according to the first embodiment of the present invention, Fig.

Referring to FIG. 4, first, the control unit 10 determines whether the braking condition is satisfied (S100).

Whether or not the braking condition is satisfied is determined based on whether the driver directly depresses the brake pedal 70 or whether or not predetermined braking conditions in a system that is operated without brake pedal pressure such as ESC, TCS, and VDC are satisfied do.

If it is determined in step S100 that the braking condition is satisfied, the control unit 10 detects the depreciation rate (S110) and determines whether the depreciation rate detected is less than the depreciation rate reference value (S120).

Is determined in step (S120), if the depreciation rate is less than the depreciation rate reference value, the control unit ¹⁰⁾ is a brake liquid volume which is to open the outlet valve 50, a front wheel wheel passes from master cylinder 80 to the accumulator 60 The braking force of the front wheel hydraulic braking system is suppressed (S130), and the braking force is applied to the rear wheel EMB system.

On the other hand, if it is determined in step S120 that the depreciation rate is not less than the depreciation rate reference value, the control unit 10 closes the outlet valve 50 and supplies the hydraulic pressure supplied from the master cylinder 80 to the front wheel, The braking force is generated in the front wheel tractive system (S140).

5 (a), the amount of brake fluid delivered to the front wheel is consumed by the accumulator 60 until the depressurization speed reaches the depreciation speed reference value, whereby the regenerative braking amount by the rear wheel EMB system is as shown in FIG. 5 The amount of regenerative braking can be increased by an amount which rises to the vertex (the point where the depreciation rate is 0.15) as compared with the conventional one as shown in (b) of FIG.

FIG. 6 is a flowchart showing a control method of the rear wheel EMB combination brake system according to the second embodiment of the present invention, and FIG. 7 is a graph showing changes in the braking force of the rear wheel EMB combination brake system according to the second embodiment of the present invention .

Referring to FIG. 6, the control unit 10 determines whether the quick braking condition is satisfied based on whether the braking demand change rate is equal to or greater than a preset braking demand change amount reference value (S200).

As a result of the determination in step S200, if the sudden braking condition is not satisfied, the controller 10 detects the depreciation rate (S210) and determines whether the depreciation rate detected is less than the depreciation rate reference value (S220).

If the discrimination result, the depreciation rate is less than the depreciation rate reference value in the step (S220), the control unit ¹⁰⁾ is to be front wheel passes from master cylinder 80 to open the outlet valve 50 such as in the above-described first example The braking force of the front wheel hydraulic braking system is suppressed by draining the amount of brake fluid to the accumulator 60 and the regenerative braking coordination control is performed with the complete response of the rear wheel EMB system, (S230).

On the other hand, when the depreciation rate is not less than the depreciation rate reference value, the controller 10 closes the outlet valve 50 and supplies the hydraulic pressure supplied from the master cylinder 80 to the front wheel, thereby generating the braking force in the front wheel hydraulic braking system, The regenerative braking coordination control is performed with the complete response responsiveness of the rear wheel EMB system by performing predetermined complete control for the rear wheel EMB system (S240).

As a result of the determination in step S200, if the condition for rapid braking is satisfied, the control unit 10 closes the outlet valve 50 as shown in Fig. 7A to generate the braking force of the front wheel hydraulic braking system, .

7 (b), the control unit 10 controls the rear wheel EMB system to have quick braking responsiveness by increasing the braking force of the rear wheel EMB system relatively larger than the braking force when the rapid braking condition is not satisfied .

As described above, the present embodiment suppresses the braking force of the front wheel hydraulic braking system in accordance with the depreciation speed during braking, thereby increasing the amount of regenerative braking to improve fuel economy and reduce the amount of generated carbon dioxide.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, I will understand. Accordingly, the true scope of the present invention should be determined by the following claims.

10:
20: TCV
30: HSV
40: inlet valve
50: Outlet valve
60: Accumulator
70: Brake pedal
80: master cylinder

Claims (13)

Determining whether the depressing speed is less than or equal to the depressed speed reference value by comparing the depressing speed with a predetermined depreciation speed reference value when the braking operation is performed; And
And controlling the braking force of the front wheel hydraulic pressure braking system until the depressing speed reaches the depression rate reference value according to the determination result.
The braking system according to claim 1, wherein in the step of suppressing the braking force of the front wheel hydraulic braking system,
Wherein the control unit cuts off the wheel pressure supplied to the front wheel from the master cylinder of the hydraulic circuit.
The control method of a rear wheel EMB combination brake system according to claim 1, wherein, when the depressing speed exceeds the reference value of the depression rate, the control unit generates the braking force of the front wheel hydraulic braking system.
2. The control method of a rear wheel EMB combination brake system according to claim 1, wherein the depression rate reference value is a depreciation rate expected to cause no rear wheel lock when the braking force of the rear wheel EMB system is generated.
Determining whether the control unit satisfies a predetermined quick braking condition; And
And controlling the braking force of the front wheel hydraulic braking system based on whether or not the quick braking condition is satisfied.
6. The method according to claim 5, wherein, in the step of determining whether the quick braking condition is satisfied,
Wherein the control unit determines that the rapid braking condition is satisfied if the braking demand change rate is equal to or greater than a predetermined braking demand change rate reference value.
6. The method according to claim 5, wherein, in the step of selectively suppressing the braking force of the front wheel hydraulic braking system,
Wherein the control unit suppresses the braking force of the front wheel hydraulic braking system if the sudden braking condition is not satisfied.
The control method of a rear wheel EMB combination brake system according to claim 7, wherein the control unit suppresses the braking force of the front wheel hydraulic braking system when the depreciation speed is less than a preset depreciation speed reference value.
The control method for a rear wheel EMB combination brake system according to claim 8, wherein the control unit cuts off the wheel pressure supplied to the front wheel from the master cylinder of the hydraulic circuit to thereby suppress the braking force of the front wheel hydraulic braking system.
The control method of a rear wheel EMB combination brake system according to claim 8, wherein the control unit generates the braking force of the front wheel hydraulic braking system when the depreciation speed is equal to or greater than the reference value of the depreciation rate.
The control method of a rear wheel EMB combination brake system according to claim 8, wherein, when the braking force of the rear wheel EMB system is generated only, the depression rate reference value is a depreciation rate expected to prevent a rear wheel lock.
6. The method according to claim 5, wherein, in the step of selectively suppressing the braking force of the front wheel hydraulic braking system,
Wherein the control unit generates the braking force of the front wheel hydraulic braking system when the control unit satisfies the rapid braking condition.
13. The control method of a rear wheel EMB combination brake system according to claim 12, wherein the controller increases the braking force of the rear wheel EMB system relatively larger than the braking force of the rear wheel EMB system when the rapid braking condition is not satisfied.

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