Electronic brake system and control method thereof

An electronic brake system comprising:

• a master cylinder including a piston to generate hydraulic pressure by applying pressure to brake oil;
• an input rod configured to be moved forward by a driver's manipulation of a brake pedal, and arranged coaxially to the master cylinder and spaced a predetermined isolation gap apart from the piston of the master cylinder;
• an electrically-driven booster including a motor, a ball screw to move the piston, and a motion converting unit to move the ball screw forward and backward by converting rotational movement of the motor into linear movement of the ball screw;
• and
• an electronic control unit to control operation of the motor based on the size of the isolation gap between the input rod and the piston,
• wherein when the ball screw of the electrically-driven booster is moved backward in an ABS mode, the electronic control unit stops backward-movement of the ball screw before the piston collides with the input rod.

A control method of an electronic brake system including a master cylinder including a piston to generate hydraulic pressure by applying pressure to brake oil, an output rod configured to contact the piston, an input rod configured to be moved forward by a driver's manipulation of a brake pedal and arranged coaxially to the master cylinder and spaced a predetermined isolation gap apart from the output rod contacting the piston of the master cylinder, and an electrically-driven booster including a motor, a ball screw to move the output rod, and a motion converting unit to move the ball screw forward and backward by converting rotational movement of the motor into linear movement of the ball screw, the control method comprising:

• determining whether there is a need to move the ball screw of the electrically-driven booster backward in an ABS mode;
• upon determining that there is a need to move the ball screw of the electrically-driven booster backward, driving the motor so that the ball screw of the electrically-driven booster is moved backward;
• and
• controlling operation of the motor based on the size of the isolation gap between the input rod and the output rod to stop backward-movement of the ball screw before the output rod collides with the input rod.