Patent ID: 6877821

Claim:
A vehicular motor-driven brake device comprising: a pedal operation amount detection portion for detecting an operation amount of a brake pedal; an actuator that moves a rod in accordance with the operation amount of the brake pedal; a master cylinder having a piston which generates a master cylinder pressure that sucks up brake fluid from a master reservoir as a result of reciprocation caused by movement of the rod; a wheel cylinder for generating braking force to a vehicle wheel using a wheel cylinder pressure that is generated based on the master cylinder pressure; a pressure increase valve provided in a conduit that connects the master cylinder and the wheel cylinder for regulating the master cylinder pressure so as to output the wheel cylinder pressure; a pressure decrease valve connected to the wheel cylinder for regulating the wheel cylinder pressure and discharging brake fluid in accordance with decrease of the wheel cylinder pressure; a piping system for directly returning brake fluid discharged by the pressure decrease valve to the master reservoir when the wheel cylinder pressure decreases; and a control portion for outputting respective drive signals to the actuator, the pressure increase valve and the pressure decrease valve, wherein the control portion executes a fluid amount replenishment control in which the actuator moves the rod such that a return stroke is performed by the piston in a predetermined time and in a direction that decreases the master cylinder pressure, during pressure increase of the master cylinder, and following this, moves the rod in a direction that causes the master cylinder pressure to increase.