Patent ID: 6655513
Filing Date: 2003-12-02
Classification: B60T

Abstract:
A hydraulic brake device for a vehicle, comprising:a master cylinder having a master piston for supplying brake pressure in response to brake pedal depression; an assisting device for assisting actuation of the master piston in response to brake pedal depression; an auxiliary piston including an effective cross-sectional area larger than that of the master piston and being operatively associated with the assisting operation of the assisting device; a pressure transmitting chamber provided between the auxiliary piston and the master piston, the pressure transmitting chamber being defined around an outer surface of the master piston; and a valve mechanism for hydraulically closing the pressure transmitting chamber when the actuation of the master piston is assisted by the assisting device through the auxiliary piston and establishing hydraulic communication between the pressure transmitting chamber and a reservoir of the master cylinder when the actuation of the master piston is not assisted by the assisting device.