VEHICLE BRAKE SYSTEM HAVING PLUNGER POWER SOURCE

The invention relates to an improved plunger assembly for a vehicle brake system. The plunger assembly is operable as a pressure source to control brake fluid pressure supplied to one or more wheel brakes. The plunger assembly comprises a housing defining a cylinder; a reversible motor supported by the housing and having a rotor; and a linear actuator such as a ball screw/nut mechanism driven by the motor. A plunger head is mounted in the cylinder and driven by the linear actuator in first and second opposite directions. Improvements include the plunger assembly engage at least one seal that defines a portion of a pressurized chamber. An end cap covers the projecting end of the cylinder and is secured to the housing to define a fluid passageway between the end of the cylinder and at least one fluid passageway provided in the housing block.