Patent ID: 8833869
Filing Date: 2014-09-16
Classification: B60T

Abstract:
1. A vehicle brake system, comprising: an input piston that moves based on an operation of a brake pedal; an assist piston that moves by an electric motor; a master cylinder that generates a fluid pressure of a brake fluid based on both of said input piston and said assist piston; a stroke sensor that detects an operation stroke of said brake pedal and provides a detection signal based on the operation stroke; and a control unit that controls said electric motor; wherein said control unit controls said electric motor based on the operation stroke of said brake pedal, and changes responsiveness of control of said electric motor to the operation stroke of said brake pedal based on a traveling state of a vehicle so that (a) responsiveness of the control of said electric motor at a lower wheel speed of said vehicle is lower than responsiveness of the control of said electric motor at a higher wheel speed of said vehicle above the lower wheel speed, and (b) responsiveness of the control of said electric motor when the detection signal of said stroke sensor increases is higher than responsiveness of the control of said electric motor when the detection signal of said stroke sensor decreases; wherein said control unit has a dead zone processing unit that performs processing of responding to an input value when said input value corresponding to the operation stroke of said brake pedal changes beyond a predetermined dead zone amount, and a dead zone amount setting unit that sets the predetermined dead zone amount of the dead zone processing unit in accordance with the traveling state of said vehicle; and wherein said dead zone amount setting unit sets said predetermined dead zone amount to be larger at the lower wheel speed of said vehicle than at the higher wheel speed of said vehicle.