Patent ID: 6550245
Filing Date: 2003-04-22
Classification: B60T

Abstract:
A hydraulic brake apparatus for a vehicle comprising:a brake operating member; a reservoir; a master cylinder for generating a brake hydraulic pressure by increasing a pressure of brake fluid from the reservoir; a master piston provided in the master cylinder and movable in response to operation of the brake operating member; a power piston disposed behind the master piston; a closed chamber defined between the master piston and the power piston; a power chamber defined by the power piston and behind the power piston; an auxiliary hydraulic pressure source for generating a power hydraulic pressure by increasing the brake fluid from the reservoir to a predetermined hydraulic pressure; a pressure regulating device connected to the auxiliary hydraulic pressure source and to the reservoir, with the power hydraulic pressure output from the auxiliary hydraulic pressure source being regulated to a predetermined hydraulic pressure and fed to the power chamber; a reaction force member disposed at a front end portion of the power piston and exposed towards the closed chamber; a retaining device disposed to maintain the reaction force member exposed towards the closed chamber, with a reaction force of the master piston in a rearward direction being transmitted directly to the front end portion of the power piston while bypassing the reaction force member when the hydraulic pressure in the closed chamber becomes less than a predetermined hydraulic pressure.