Hydraulic brake actuator

A hydraulic brake actuator for use in an automobile brake system which includes a master cylinder to be operated by a driver and a wheel cylinder connected to the master cylinder through a hydraulic circuit for applying a braking force to a wheel, said brake actuator being interposed in said hydraulic circuit and comprising:

• a control cylinder means having a first chamber connected to said master cylinder, a second chamber which is connected to said wheel cylinder and which can be selectively connected to said master cylinder and disconnected therefrom, and an axially displaceable piston accommodated in said chambers for changing respective volumes of said chambers;
• a piston driver means for causing an axial displacement of said piston;
• an accumulator means connected to said first chamber;
• and
• a valve means having an inlet port connected to said master cylinder, and an outlet port connected to said second chamber, said valve means being operatively connected to said piston so as to be opened or closed in response to the displacement of said piston.