Patent ID: 8777331

Claim:
A brake booster for use in a hydraulic braking system having a brake pedal, a master cylinder, and a hydraulic control unit, the brake booster comprising: a housing; a screw drive arrangement positioned at least partially in the housing; a motor coupled to the housing for actuating the screw drive arrangement; and a piston assembly positioned in the housing, the piston assembly and the housing together at least partially defining a first fluid chamber having an opening for providing fluid communication with the master cylinder; and a second fluid chamber having an opening for providing fluid communication with the hydraulic control unit; wherein the screw drive arrangement is movable relative to a piston of the piston assembly between an engaged position, in which the screw drive arrangement engages the piston and seals an opening in the piston such that the first fluid chamber is isolated from the second fluid chamber, and a disengaged position in which the screw drive arrangement does not seal the opening in the piston such that the first fluid chamber is not isolated from the second fluid chamber.