Patent ID: 6543860
Filing Date: 2003-04-08
Classification: B60T

Abstract:
A hydraulic pressure brake device comprising:a master cylinder; a brake operating member; a master piston provided in the master cylinder and movable in a forward direction in response to an input force applied to the brake operating member, the master piston having an effective cross-sectional area; boosting means provided between the master cylinder and the brake operating member to assist the movement of the master piston in response to the input force applied to the brake operating member; a first auxiliary piston disposed rearwardly of the master piston in the master cylinder and having a larger effective cross-sectional area than the effective cross-sectional area of the master piston; a pressure transmitting chamber disposed between the first auxiliary piston and the master piston; valve means disposed in the first auxiliary piston for hydraulically sealing the pressure transmitting chamber when the movement of the master piston is assisted by the boosting means and for connecting the pressure transmitting chamber with a reservoir when the movement of the master piston is not assisted by the boosting means; and a second auxiliary piston disposed between the first auxiliary piston and the boosting means for transmitting the boosting power generated by the boosting means to the first auxiliary piston when the movement of the master piston is assisted by the boosting means and for transmitting the input force applied to the brake operating member to the valve means to open the valve means when the movement of the master piston is not assisted by the boosting means.