KR102525956B1 - Electric brake system and control method thereof - Google Patents

Abstract

An electronic brake system and a control method thereof are disclosed. An electronic brake system according to an embodiment of the present invention generates hydraulic pressure by moving a piston using a reservoir in which oil is stored, a master cylinder connected to the reservoir and discharging oil according to the effort of a brake pedal, and a rotational force of a motor. A hydraulic control device having a hydraulic pressure supply device for supplying the generated hydraulic pressure to the wheel cylinders provided on each wheel, a hydraulic circuit that transfers the hydraulic pressure discharged from the hydraulic pressure supply device to the wheel cylinders provided on each wheel, and a hydraulic circuit pressure During operation of the detecting pressure sensor and ABS (Anti-Lock Brake System), the hydraulic circuit target pressure is set according to the road surface condition, and the hydraulic circuit pressure detected through the pressure sensor reaches the set hydraulic circuit target pressure. It includes an electronic control unit that controls

Description

Electronic brake system and its control method {ELECTRIC BRAKE SYSTEM AND CONTROL METHOD THEREOF}

The present invention relates to an electronic brake system and a control method thereof, and more particularly, to an electronic brake system generating a braking force according to an electrical signal corresponding to a displacement of a brake pedal and a control method thereof.

In general, a brake system for braking is necessarily installed in a vehicle, and recently, various types of systems for obtaining stronger and more stable braking force have been proposed.

An example of the brake system is an anti-lock brake system (ABS) that prevents wheel slippage during braking, and a brake traction control system (BTCS: Brake A traction control system), and an electronic stability control system (ESC) that stably maintains a driving state of a vehicle by controlling brake hydraulic pressure by combining an anti-lock brake system and traction control.

In the conventional brake system, when a driver steps on the brake pedal, hydraulic pressure necessary for braking is supplied to the wheel cylinder using a mechanically connected vacuum booster.

Recently, an electronic brake system has been developed in which a high-pressure brake pressure is generated using a motor instead of a vacuum booster and braking force is generated using the high-pressure brake pressure.

This electronic brake system includes a hydraulic pressure supply device for generating hydraulic pressure by moving a piston using rotational force of a motor and supplying the generated hydraulic pressure to a wheel cylinder provided on each wheel, and hydraulic pressure transmitted to each wheel cylinder by the hydraulic pressure supply device. It includes a hydraulic control device with a hydraulic circuit that controls the flow of

Conventionally, when the driver steps on the brake pedal, the displacement of the brake pedal is detected through a pedal displacement sensor that detects the displacement of the brake pedal, the driver's required target pressure is calculated based on the detected brake pedal displacement, and the calculated driver's required target pressure is set as the target pressure of the hydraulic circuit, and hydraulic pressure is generated by moving the piston using the rotational force of the motor so that the pressure of the hydraulic circuit reaches the set target pressure.

However, since the conventional closing and opening of the inlet valve and the outlet valve in the hydraulic circuit repeatedly occur during ABS operation, the pressure volume of the hydraulic circuit changes frequently. Because of this, the amount of pressure fluctuation in the hydraulic circuit is large. In this situation, when the target pressure of the hydraulic circuit is high during ABS operation, the pressure fluctuation of the hydraulic circuit is made at a high pressure level, which increases the fatigue of the system (eg, components of the hydraulic pressure supply device) and improves the durability of the system. can fall

Also, conventionally, when the target pressure of the hydraulic circuit is high during ABS operation, ABS operating noise may increase because the inlet valve and the outlet valve of the hydraulic circuit are opened and closed in the high pressure state.

Publication No. 10-2012-0079093 (published on July 11, 2012)

An embodiment of the present invention is to provide an electronic brake system and a control method thereof that improve durability of the system and reduce ABS operation noise during ABS operation.

According to one aspect of the present invention, a reservoir in which oil is stored; a master cylinder connected to the reservoir and discharging oil according to the pressure of the brake pedal; A hydraulic pressure supply device for generating hydraulic pressure by moving a piston using rotational force of a motor and supplying the generated hydraulic pressure to a wheel cylinder provided on each wheel; a hydraulic control device having a hydraulic circuit that transfers the hydraulic pressure discharged from the hydraulic pressure supply device to wheel cylinders provided on each wheel; a pressure sensor for detecting the pressure of the hydraulic circuit; and while ABS (Anti-Lock Brake System) is operating, the hydraulic circuit target pressure is set according to the condition of the road surface, and the hydraulic pressure supply device is controlled so that the hydraulic circuit pressure detected through the pressure sensor reaches the set hydraulic circuit target pressure. An electronic brake system including an electronic control unit that does may be provided.

In addition, when the road surface is not determined during ABS operation, the electronic control unit may determine a skid pressure level and set a target pressure of the hydraulic circuit based on the determined skid pressure level and a preset target differential pressure.

In addition, the electronic control unit may determine, as the skid pressure level, the highest wheel pressure among wheel pressures of wheel cylinders provided on each wheel.

In addition, when the road surface is determined during ABS operation, the electronic control unit determines a skid pressure level according to the determined road surface condition, and sets a target pressure of the hydraulic circuit based on the determined skid pressure level and a preset target differential pressure. can be set.

In addition, in order to minimize unnecessary pressure fluctuations in the hydraulic circuit as the determined skid pressure level fluctuates, the electronic control unit controls the hydraulic pressure immediately before the control only for the positive change in the skid pressure level based on the target pressure of the hydraulic circuit immediately before the control. An increase in the circuit target pressure may be allowed.

In addition, the electronic control unit maintains the set hydraulic circuit target pressure in a state where the road surface is not determined during ABS operation, and when the road surface is determined and the hydraulic circuit target pressure needs to be reduced, in order to minimize unnecessary pressure fluctuations in the hydraulic circuit The set hydraulic circuit target pressure may be maintained in a state in which the road surface is not determined without reducing the hydraulic circuit target pressure.

In addition, the electronic control unit may increase the target pressure of the hydraulic circuit to the target pressure requested by the driver corresponding to the displacement of the brake pedal when the road surface is split or the road surface changes rapidly during the operation of the ABS. there is.

Also, the electronic control unit may set the set target pressure of the hydraulic circuit lower than the target pressure requested by the driver corresponding to the displacement of the brake pedal.

According to another aspect of the present invention, a reservoir in which oil is stored; a master cylinder connected to the reservoir and discharging oil according to the pressure of the brake pedal; A hydraulic pressure supply device for generating hydraulic pressure by moving a piston using rotational force of a motor and supplying the generated hydraulic pressure to a wheel cylinder provided on each wheel; a hydraulic control device having a hydraulic circuit that transfers the hydraulic pressure discharged from the hydraulic pressure supply device to wheel cylinders provided on each wheel; and a pressure sensor for detecting the pressure of the hydraulic circuit, wherein a target pressure of the hydraulic circuit is set according to road surface conditions during ABS (Anti-Lock Brake System) operation, and A control method of an electronic brake system may be provided in which hydraulic pressure is generated by moving the piston using rotational force of the motor so that the pressure reaches the set target pressure of the hydraulic circuit.

In addition, in setting the target pressure of the hydraulic circuit, when the road surface is not determined during the operation of the ABS, the highest wheel pressure among the wheel pressures of the wheel cylinders provided on each wheel is determined as the skid pressure level, and the determined skid pressure level A pressure obtained by summing the pressure and the preset target differential pressure may be set as the target pressure of the hydraulic circuit.

In addition, in the hydraulic circuit target pressure setting, when the road surface is determined during ABS operation, a skid pressure level according to the determined road surface condition is determined, and a pressure obtained by summing the determined skid pressure level and a preset target differential pressure is obtained. It can be set as the target pressure of the hydraulic circuit.

Embodiments of the present invention can improve the durability of the system and reduce ABS operation noise by appropriately setting the target pressure of the hydraulic circuit according to the road surface condition during ABS operation.

1 is a schematic configuration diagram of an electronic brake system according to an embodiment of the present invention.
2 is a schematic control block diagram of an electronic brake system according to an embodiment of the present invention.
3 is a view for explaining setting a target pressure of a hydraulic circuit when a road surface is not determined when an ABS is operated in an electronic brake system according to an embodiment of the present invention.
4 is a view for explaining setting a target pressure of a hydraulic circuit when a road surface is determined during ABS operation in an electronic brake system according to an embodiment of the present invention.
5 is a view for explaining correction of a target pressure of a hydraulic circuit set in an electronic brake system according to an embodiment of the present invention according to a skid pressure level.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments introduced below are provided as examples in order to sufficiently convey the spirit of the present invention to those skilled in the art to which the present invention belongs. The present invention may be embodied in other forms without being limited to the embodiments described below. In order to clearly explain the present invention, parts irrelevant to the description are omitted from the drawings, and in the drawings, the width, length, thickness, etc. of components may be exaggerated for convenience. Like reference numbers indicate like elements throughout the specification.

1 is a schematic configuration diagram of an electronic brake system according to an embodiment of the present invention.

Referring to FIG. 1, the electronic brake system includes a reservoir 10, a master cylinder 20, a wheel cylinder 30, a hydraulic pressure supply unit 40, a hydraulic control unit 50, and an electronic control unit (ECU) 60. can include

The master cylinder 20 is connected to the reservoir 10 where oil is stored and discharges oil according to the effort of the brake pedal P.

The wheel cylinder 30 performs braking of each of the wheels RR, RL, FR, and FL by the transmitted hydraulic pressure.

The hydraulic pressure supply device 40 is connected to the master cylinder 20 and generates hydraulic pressure by moving a piston using rotational force of a motor.

For example, the hydraulic pressure supply device 40 includes a cylinder block 41 in which a pressure chamber for receiving and storing oil is formed, a hydraulic piston 42 accommodated in the cylinder block 41, and the hydraulic piston 42 ) It may include a motor 43 that provides power to the hydraulic piston 42 at the rear end. The motor 43 generates rotational force by a control signal from the electronic control unit 60. The motor 43 includes a stator 43a and a rotor 43b to generate rotational force in a forward or reverse direction.

In addition, the hydraulic pressure supply device 40 includes a worm shaft 44 formed integrally with the rotational shaft of the motor 43, a worm wheel 45 rotated by the worm shaft 44, and rotation of the worm wheel 45. It may include a driving shaft 46 that moves linearly and slides the hydraulic piston 42 within the cylinder block 41 . In addition, the hydraulic pressure supply device 40 may include various valves for changing the flow path.

Looking at the operation of the hydraulic pressure supply device 40, when a displacement occurs in the brake pedal P, a detection signal is transmitted to the electronic control unit ECU by a pedal displacement sensor that detects the displacement of the brake pedal P. The electronic control unit 60 drives the motor 43 in one direction to rotate the worm shaft 44 in one direction. The rotational force of the worm shaft 44 is transmitted to the driving shaft 46 via the worm wheel 45, and the hydraulic piston 42 connected to the driving shaft 46 generates hydraulic pressure in the pressure chamber of the cylinder block 111 while moving forward. . The generated hydraulic pressure is transmitted to the hydraulic control device 50 by the operation of various valves for changing the flow path.

The hydraulic control device 50 receives the hydraulic pressure generated by the hydraulic pressure supply device 40 and transfers the hydraulic pressure to the wheel cylinders 30 provided on the wheels RR, RL, FR, and FL.

The hydraulic control device 50 includes first and second hydraulic circuits 51 and 52 that control the flow of hydraulic pressure transmitted to the wheel cylinder 30 provided on each wheel RR, RL, FL, and FR. . For example, the first hydraulic circuit 51 receives hydraulic pressure from the hydraulic pressure supply device 40 and controls the braking force of the right rear wheel RR and the left front wheel RL. The second hydraulic circuit 52 may receive hydraulic pressure from the hydraulic pressure supply device 40 and control the braking force of the left front wheel FL and the right front wheel FR. A wheel cylinder 30 is installed on each of the wheels RR, RL, FL, and FR, and braking is performed by receiving hydraulic pressure.

Each of the hydraulic circuits 51 and 52 may include four inlet valves and four outlet valves to control the flow of hydraulic pressure supplied to each wheel cylinder 30 from the hydraulic pressure supply device 40 . The inlet valve is disposed on the upstream side of the wheel cylinder 30 and is a normal open type solenoid valve that is open in normal conditions and operates to close when a closing signal is received from the electronic control unit 60. can The outlet valve may be a normally closed type solenoid valve that is normally closed but opens when an opening signal is received from the electronic control unit 60 .

The electronic control unit 60 uses the displacement information of the brake pedal P, the pressure information of the hydraulic circuits 51 and 52, and the pressure information of each wheel cylinder 30 to supply the hydraulic pressure supply device 40 and the hydraulic control device ( 50) can be controlled.

2 is a schematic control block diagram of an electronic brake system according to an embodiment of the present invention.

Referring to FIG. 2 , the electronic brake system may include an electronic control unit 60 that performs overall control.

A wheel speed sensor 70, a pedal displacement sensor 60, and a pressure sensor 90 are electrically connected to the input side of the electronic control unit 60.

The motor driving unit 100 and the valve driving unit 110 are electrically connected to the output side of the electronic control unit 60 .

The storage unit 120 is electrically connected to the input/output side of the electronic control unit 60.

The wheel speed sensor 70 is provided on each of the wheels RR, RL, FL and FR to detect the wheel speed of each wheel. Wheel speed information detected by the wheel speed sensor 70 is transmitted to the electronic control unit 60 .

The pedal displacement sensor (PTS) 80 is provided on the brake pedal (P) and detects the operation and displacement of the brake pedal (P). The pedal displacement information detected by the pedal displacement sensor 80 is transmitted to the electronic control unit 60 .

The pressure sensor (PS) 90 detects the pressure of the hydraulic circuits 51 and 52.

The pressure sensor 90 detects the hydraulic pressure transmitted from the hydraulic pressure supply device 40 to the wheel cylinder 30 installed on the right rear wheel RR or the left front wheel RL. The pressure sensor 90 may be provided at a position capable of detecting hydraulic pressure transmitted from the hydraulic pressure supply device 40 to the wheel cylinders 30 of the left front wheel FL and the right front wheel FR. Hydraulic circuit pressure information detected by the pressure sensor 90 is transmitted to the electronic control unit 60 .

The motor driving unit 100 drives the motor 43 to rotate forward or backward according to a control signal from the electronic control unit 60 .

The valve driver 110 operates various valves V of the electronic brake system.

The storage unit 120 may store various information and programs related to ABS operation determination and road surface determination. A skid pressure level corresponding to a road surface condition or vehicle deceleration may be previously stored in the storage unit 120 . The storage unit 120 stores various types of information during ABS operation.

The electronic control unit 60 performs operations necessary for controlling the electronic brake system by using a memory storing data for an algorithm that performs overall control of the electronic brake system or a program that reproduces the algorithm, and the data stored in the memory. can be implemented as a microprocessor. In this case, the memory and the processor may be implemented as separate chips. Alternatively, the memory and the processor may be implemented as a single chip.

The electronic control unit 60 calculates the vehicle speed from each wheel speed detected through the wheel speed sensor 70, and determines the vehicle deceleration from the change in the calculated vehicle speed.

The electronic control unit 60 calculates the driver's requested target pressure, which is the target pressure requested by the driver, from the pedal displacement detected through the pedal displacement sensor 80.

The electronic control unit 60 controls the hydraulic pressure supplied to the wheel cylinder 30 by controlling the hydraulic pressure supply device 40 according to the pressure of the hydraulic circuits 51 and 52 detected through the pressure sensor 90. . Specifically, the electronic control unit 60 may control the amount of brake fluid discharged from the wheel cylinder 30 and the discharge speed by adjusting the forward distance and forward speed of the hydraulic piston 42 .

The electronic control unit 60 includes displacement information of the brake pedal P detected through the pedal displacement sensor 80 during ABS operation, pressure information of the hydraulic circuits 51 and 52 detected through the pressure sensor 90, and , Various valves included in the electronic brake system, including the motor 43, are controlled using the pressure information of each wheel cylinder 30.

The electronic control unit 60 detects the displacement of the brake pedal P through the pedal displacement sensor 80 during ABS operation, calculates the driver's required target pressure based on the detected brake pedal displacement, and the hydraulic circuit 51, 52) is set below the calculated target pressure required by the driver, and the rotational force of the motor 43 is used so that the pressures of the hydraulic circuits 51 and 52 satisfy the set target pressures of the hydraulic circuits 51 and 52. Hydraulic piston 42 is moved to generate hydraulic pressure.

The electronic control unit 60 sets the hydraulic circuit target pressure according to the condition of the road surface during ABS operation. The electronic control unit 60 determines the skid pressure level when the ABS is operating, and based on the determined skid pressure level and the target delta pressure, the target pressure of the hydraulic circuits 51 and 52 (Circuit target pressure).

The electronic control unit 60 determines the road surface during ABS operation. After starting ABS, a minimum amount of time is required to determine the road surface. Usually, the road surface can be judged after one or two ABS cycles have elapsed.

The electronic control unit 60 sets the target pressures of the hydraulic circuits 51 and 52 in different ways depending on whether or not the road surface is judged during ABS operation.

When the road surface is not determined during ABS operation, the electronic control unit 60 sets target pressures of the hydraulic circuits 51 and 52 based on the skid pressure level and the preset target differential pressure.

The electronic control unit 60 sets the target pressure of the hydraulic circuits 51 and 52 based on the skid pressure level and the preset target differential pressure when the value estimated for the road surface during ABS operation is not valid.

When the road surface is determined during ABS operation, the electronic control unit 60 sets the target pressure of the hydraulic circuits 51 and 52 based on the target differential pressure and skid pressure level determined by the vehicle deceleration or the determined road surface condition. .

The electronic control unit 60 sets the target pressure of the hydraulic circuits 51 and 52 based on the target differential pressure and skid pressure level determined by the vehicle deceleration or the determined road surface condition when the value estimated for the road surface during ABS operation is valid. set

Therefore, by having the above configuration, one embodiment of the present invention can lower the target pressure level of the hydraulic circuit by appropriately setting the target pressure of the hydraulic circuit according to the road surface condition during ABS operation, thereby improving the durability of the system and ABS Operation noise can be reduced.

3 is a view for explaining setting a target pressure of a hydraulic circuit when a road surface is not determined when an ABS is operated in an electronic brake system according to an embodiment of the present invention.

Referring to FIG. 3, when the ABS is operated by the ABS operation flag at time t1, and the road surface is not determined because the value estimated for the road surface during ABS operation is not valid, the hydraulic circuit target pressure is obtained by the following equation [1] It can be set as

Hydraulic circuit target pressure = skid pressure level + target differential pressure - Equation [1]

In this way, the sum of the skid pressure level and the target differential pressure can be set as the hydraulic circuit target pressure.

The skid pressure level may be the highest estimated wheel pressure among estimated wheel pressures obtained by estimating the pressure of each wheel cylinder 30 immediately after the ABS operates. The estimated wheel pressure may be estimated using a duty ratio of pulse width modulation (PWM) control of the inlet valve and the outlet valve of each wheel cylinder 30 . For reference, the inlet valve is controlled by Linear Flow Control (LFC), which linearly increases wheel pressure by adjusting the opening amount of the valve by varying the PWM duty ratio supplied thereto. The outlet valve can be on/off controlled.

The target differential pressure may be a preset pressure.

When setting the hydraulic circuit target pressure, the hydraulic circuit target pressure is set below the driver's required target pressure.

In this way, the target pressure of the hydraulic circuit can be lowered than the target pressure requested by the driver. Due to this, the durability of the system can be improved and ABS operation noise can be reduced.

4 is a view for explaining setting a target pressure of a hydraulic circuit when a road surface is determined during ABS operation in an electronic brake system according to an embodiment of the present invention.

Referring to FIG. 4 , when the road surface is determined as a value obtained by estimating the road surface during ABS operation is valid, the hydraulic circuit target pressure may be set as in Equation [2] below.

Hydraulic circuit target pressure = skid pressure level according to road surface condition + target differential pressure - Equation [2]

In this way, the pressure obtained by adding the target differential pressure and the skid pressure level according to the road surface condition may be set as the hydraulic circuit target pressure.

The skid pressure level may be preset to correspond to the road surface condition.

The skid pressure level may be preset to correspond to vehicle deceleration indicating road surface conditions.

The target differential pressure may be a preset pressure.

When setting the hydraulic circuit target pressure, the hydraulic circuit target pressure is set below the driver's required target pressure.

In this way, the target pressure of the hydraulic circuit can be lowered than the target pressure requested by the driver. Due to this, the durability of the system can be improved and ABS operation noise can be reduced.

5 is a view for explaining correction of a target pressure of a hydraulic circuit set in an electronic brake system according to an embodiment of the present invention according to a skid pressure level.

Referring to FIG. 5, in order to minimize unnecessary pressure fluctuations in the hydraulic circuits 51 and 52 caused by the fluctuation of the skid pressure level due to the change of the road surface, the positive of the skid pressure level based on the target pressure of the hydraulic circuit immediately before control ( +) Allows an increase in the hydraulic circuit target pressure only for fluctuations.

When the skid pressure level increases from P1 to P2 as at time t1, the hydraulic circuit target pressure also increases.

However, when the skid pressure level decreases from P2 to P1 as at the time t2, the target pressure of the hydraulic circuit immediately prior to control is maintained as it is without reducing the target pressure of the hydraulic circuit.

If the skid pressure level increases from P1 to P3 at the time of t3, since it is a positive change, the hydraulic circuit target pressure is increased accordingly. For reference, even if the skid pressure level increases from P1 to P3 but to P1' (P1<P1'<P2), which is higher than P1 and lower than P2 at the time of t3, it will be lower than the target pressure of the hydraulic circuit immediately before control. Maintain the hydraulic circuit target pressure.

On the other hand, when ABS operates, the set hydraulic circuit target pressure is maintained in a state where the road surface is not determined, and when the road surface is determined and the hydraulic circuit target pressure needs to be reduced, the hydraulic circuit is operated to minimize unnecessary pressure fluctuations in the hydraulic circuits 51 and 52. The set hydraulic circuit target pressure is maintained as it is without reducing the target pressure and in a state where the road surface is not determined.

In addition, when the friction coefficient of the left and right road surfaces during ABS operation is substantially the same on a split road surface or when the road surface changes rapidly (for example, a change from a low-friction road surface to a high-friction road surface), a hydraulic circuit for stable braking Increase the target pressure of (51,52) to the target pressure level requested by the driver.

10: reservoir 20: master cylinder
30: wheel cylinder 40: hydraulic supply
50: hydraulic control device 60: electronic control unit
70: wheel speed sensor 80: pedal displacement sensor
90: pressure sensor 100: motor drive unit
110: valve driving unit 120: storage unit

Claims (11)

delete A reservoir in which oil is stored;
a master cylinder connected to the reservoir and discharging oil according to the pressure of the brake pedal;
A hydraulic pressure supply device for generating hydraulic pressure by moving a piston using rotational force of a motor and supplying the generated hydraulic pressure to a wheel cylinder provided on each wheel;
a hydraulic control device having a hydraulic circuit that transfers the hydraulic pressure discharged from the hydraulic pressure supply device to wheel cylinders provided on each wheel;
a pressure sensor for detecting the pressure of the hydraulic circuit; and
Controlling the hydraulic pressure supply device so that the hydraulic circuit target pressure detected by the pressure sensor reaches the set hydraulic circuit target pressure by setting the hydraulic circuit target pressure according to the condition of the road surface during ABS (Anti-Lock Brake System) operation. including an electronic control unit;
The electronic control unit determines a skid pressure level when the road surface is not determined during ABS operation, and sets a target pressure of the hydraulic circuit based on the determined skid pressure level and a preset target differential pressure. According to claim 2,
The electronic control unit determines the highest wheel pressure among wheel pressures of wheel cylinders provided on each wheel as the skid pressure level. A reservoir in which oil is stored;
a master cylinder connected to the reservoir and discharging oil according to the pressure of the brake pedal;
A hydraulic pressure supply device for generating hydraulic pressure by moving a piston using rotational force of a motor and supplying the generated hydraulic pressure to a wheel cylinder provided on each wheel;
a hydraulic control device having a hydraulic circuit that transfers the hydraulic pressure discharged from the hydraulic pressure supply device to wheel cylinders provided on each wheel;
a pressure sensor for detecting the pressure of the hydraulic circuit; and
Controlling the hydraulic pressure supply device so that the hydraulic circuit target pressure detected by the pressure sensor reaches the set hydraulic circuit target pressure by setting the hydraulic circuit target pressure according to the condition of the road surface during ABS (Anti-Lock Brake System) operation. including an electronic control unit;
When the road surface is determined during ABS operation, the electronic control unit determines a skid pressure level according to the determined road surface condition, and sets a target pressure of the hydraulic circuit based on the determined skid pressure level and a preset target differential pressure. electronic brake system. According to claim 4,
In order to minimize unnecessary pressure fluctuations in the hydraulic circuit as the determined skid pressure level fluctuates, the electronic control unit sets the hydraulic circuit target pressure just before the control only for the positive change in the skid pressure level based on the hydraulic circuit target pressure immediately before the control. An electronic brake system that allows an increase in pressure. A reservoir in which oil is stored;
a master cylinder connected to the reservoir and discharging oil according to the pressure of the brake pedal;
A hydraulic pressure supply device for generating hydraulic pressure by moving a piston using rotational force of a motor and supplying the generated hydraulic pressure to a wheel cylinder provided on each wheel;
a hydraulic control device having a hydraulic circuit that transfers the hydraulic pressure discharged from the hydraulic pressure supply device to wheel cylinders provided on each wheel;
a pressure sensor for detecting the pressure of the hydraulic circuit; and
Controlling the hydraulic pressure supply device so that the hydraulic circuit target pressure detected by the pressure sensor reaches the set hydraulic circuit target pressure by setting the hydraulic circuit target pressure according to the condition of the road surface during ABS (Anti-Lock Brake System) operation. including an electronic control unit;
The electronic control unit maintains the set hydraulic circuit target pressure in a state where the road surface is not determined when the ABS is operating, and when the road surface is determined and the hydraulic circuit target pressure needs to be reduced, the hydraulic pressure circuit minimizes unnecessary pressure fluctuations in the hydraulic circuit. An electronic brake system that maintains a set hydraulic circuit target pressure in a state where the road surface is not determined without reducing the circuit target pressure. According to claim 4,
The electronic control unit increases the target pressure of the hydraulic circuit to the target pressure required by the driver corresponding to the displacement of the brake pedal when the road surface is split or the road surface changes rapidly during ABS operation. . The method of any one of claims 2, 4 and 6,
The electronic control unit sets the set target pressure of the hydraulic circuit lower than the target pressure requested by the driver corresponding to the displacement of the brake pedal. delete A reservoir in which oil is stored; a master cylinder connected to the reservoir and discharging oil according to the pressure of the brake pedal; A hydraulic pressure supply device for generating hydraulic pressure by moving a piston using rotational force of a motor and supplying the generated hydraulic pressure to a wheel cylinder provided on each wheel; a hydraulic control device having a hydraulic circuit that transfers the hydraulic pressure discharged from the hydraulic pressure supply device to wheel cylinders provided on each wheel; And in the control method of the electronic brake system including a pressure sensor for detecting the pressure of the hydraulic circuit,
During ABS (Anti-Lock Brake System) operation, the hydraulic circuit target pressure is set according to the condition of the road surface,
generating hydraulic pressure by moving the piston using rotational force of the motor so that the pressure of the hydraulic circuit reaches the set target pressure of the hydraulic circuit;
In the hydraulic circuit target pressure setting, when the road surface is not determined during the operation of the ABS, the highest wheel pressure among the wheel pressures of the wheel cylinders provided on each wheel is determined as the skid pressure level, and the determined skid pressure level and the predetermined skid pressure level are determined. A control method of an electronic brake system for setting the sum of the target differential pressures as the target pressure of the hydraulic circuit. A reservoir in which oil is stored; a master cylinder connected to the reservoir and discharging oil according to the pressure of the brake pedal; A hydraulic pressure supply device for generating hydraulic pressure by moving a piston using rotational force of a motor and supplying the generated hydraulic pressure to a wheel cylinder provided on each wheel; a hydraulic control device having a hydraulic circuit that transfers the hydraulic pressure discharged from the hydraulic pressure supply device to wheel cylinders provided on each wheel; And in the control method of the electronic brake system including a pressure sensor for detecting the pressure of the hydraulic circuit,
During ABS (Anti-Lock Brake System) operation, the hydraulic circuit target pressure is set according to the condition of the road surface,
generating hydraulic pressure by moving the piston using rotational force of the motor so that the pressure of the hydraulic circuit reaches the set target pressure of the hydraulic circuit;
In the hydraulic circuit target pressure setting, when the road surface is determined during ABS operation, a skid pressure level according to the determined road surface condition is determined, and a pressure obtained by adding the determined skid pressure level and a preset target differential pressure is determined as the hydraulic pressure. A control method of the electronic brake system that sets the target pressure of the circuit.

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