Electric brake system and method for controlling the same

1. An electric brake system comprising:

a master cylinder configured to generate hydraulic pressure corresponding to a displacement of a brake pedal;

a hydraulic circuit configured to transfer the hydraulic pressure generated by the master cylinder to at least one wheel;

an actuator connected to a passage connecting between the master cylinder and the hydraulic circuit and configured to generate hydraulic pressure using a piston operated by an electric signal generated in response to the displacement of the brake pedal, the actuator comprising a motor configured to drive the piston;

a sensing unit configured to sense driver's braking intention; and

a controller configured to calculate a change amount of stroke of the piston of the actuator, connected to a passage connecting between the master cylinder and the hydraulic circuit, needed to output brake pressure corresponding to the driver's braking intention, and control the motor of the actuator to change a torque generated by the motor of the actuator in response to the calculated change amount of the stroke of the piston of the actuator so as to boost pressure of each wheel at a predetermined slope so that the torque generated by the motor of the actuator reduces the difference between the brake pressure corresponding to the driver's braking intention and the pressure of each wheel.

2. The electric brake system according to claim 1 , further comprising

a cut valve disposed between the master cylinder and the hydraulic circuit, and configured to control flow of oil.

3. The electric brake system according to claim 2 , wherein the actuator includes:

the motor configured to generate power according to the electric signal of the brake pedal; and

the piston configured to generate displacement based on the generated power.

4. The electric brake system according to claim 3 , wherein the sensing unit further includes:

a pedal stroke sensor configured to sense displacement of the brake pedal.

5. The electric brake system according to claim 4 , wherein:

the controller, in response to operation of an electronic stability control (ESC) of a vehicle, calculates the change amount of stroke of the piston of the actuator needed to output the brake pressure corresponding to the driver's braking intention, and

the operation of electronic stability control (ESC) of the vehicle includes: operating an anti-lock brake system (ABS), a traction control system (TCS) or an electronically stability control (ESC) system.

6. The electric brake system according to claim 4 , wherein the controller, in response to operation of an electronic stability control (ESC) of a vehicle, calculates the change amount of stroke of the piston of the actuator needed to output the brake pressure corresponding to the driver's braking intention, and controls pressure of each wheel by controlling torque of the motor, during the anti-lock brake system (ABS) operation.

7. The electric brake system according to claim 1 , wherein:

the controller, when a difference between brake pressure requested by the driver and pressure of at least one wheel is higher than a predetermined threshold value, calculates the change amount of stroke of the piston in a manner that brake pressure corresponding to the driver's braking intention, and acquires the calculated stroke change amount so as to boost the pressure of each wheel at the predetermined slope.

8. The electric brake system according to claim 7 , wherein the controller controls the position of the piston so as to acquire the calculated stroke change amount.

9. The electric brake system according to claim 1 , wherein:

the controller is configured to change the predetermined slope within a range that does not exceed a maximum slope (Max Slope) and a maximum operation time (Max Time) to boost the pressure of each wheel based on the changed predetermined slope.

10. The electric brake system according to claim 1 , further comprising a switching valve positioned between the actuator and the passage which connects between the master cylinder and the hydraulic circuit.

11. The electric brake system according to claim 10 , wherein the switching valve is a normally closed solenoid valve.

12. A method for controlling an electric brake system that includes a master cylinder configured to generate hydraulic pressure corresponding to a displacement of a brake pedal, a hydraulic circuit configured to transfer the hydraulic pressure generated by the master cylinder to at least one wheel, an actuator generating hydraulic pressure using a piston operated by a motor in response to an electric signal generated in response to the displacement of the brake pedal, the method comprising:

sensing driver's braking intention; and

when an electronic stability control (ESC) of a vehicle operates, calculating a change amount of stroke of the piston of the actuator, connected to a passage connecting between the master cylinder and the hydraulic circuit, needed to output brake pressure corresponding to the driver's braking intention, and controlling the motor of the actuator to change a torque generated by the motor of the actuator in response to the calculated change amount of the stroke of the piston of the actuator so as to boost pressure of each wheel at a predetermined slope so that the torque generated by the motor of the actuator reduces difference between the brake pressure corresponding to the driver's braking intention and the pressure of each wheel.

13. The method according to claim 12 , wherein the brake system includes:

a cut valve disposed between the master cylinder and the hydraulic circuit, and configured to control flow of oil.

14. The method according to claim 12 , wherein the actuator includes:

the motor configured to generate power according to an electric signal of the brake pedal; and

the piston configured to generate displacement based on the generated power.

15. The method according to claim 14 , wherein the driver's braking intention is detected through the displacement of the brake pedal.

16. The method according to claim 15 , wherein the operation of electronic stability control (ESC) of the vehicle includes:

operating an anti-lock brake system (ABS), a traction control system (TCS) or an electronically stability control (ESC) system.

17. The method according to claim 16 , further comprising:

controlling pressure of each wheel by controlling torque of the motor, during the anti-lock brake system (ABS) operation.

18. The method according to claim 17 , further comprising:

when a difference between brake pressure requested by the driver and pressure of at least one wheel is higher than a predetermined threshold value, calculating the change amount of stroke of the piston.

19. The method according to claim 18 , wherein the acquiring of the calculated stroke change amount to boost pressure of each wheel at the predetermined slope includes:

controlling the position of the piston.

20. The method according to claim 12 , wherein the acquiring of the calculated stroke change amount to boost pressure of each wheel at the predetermined slope includes:

changing the predetermined slope within a range that does not exceed a maximum slope (Max Slope) and a maximum operation time (Max Time); and

boosting the pressure of each wheel based on the changed predetermined slope.