Patent ID: 6079797
Filing Date: 2000-06-27
Classification: B60T,F04B

Abstract:
A vehicular anti-lock braking system for hydraulically actuated wheel brakes comprising:a source of pressurized fluid;a hydraulic control unit controlling fluid from the source of pressurized fluid to and from the wheel brakes;at least one fluid control valve mounted on the hydraulic control unit between the source of pressurized fluid and the wheel brakes; anda dual acting ball screw pump assembly, mounted on the hydraulic control unit, selectively providing pressurized fluid to the wheel brakes through the control valve, the ball screw pump assembly includinga pump body having an axial bore defining a travel chamber and a pressure chamber, the pressure chamber divided into an input chamber and an output chamber by a reciprocating piston received in the pressure chamber, the input chamber hydraulically connected between the control valve and the wheel brakes, the output chamber hydraulically connected between the source of pressurized fluid and the control valve, anda conduit, formed in the pump body, hydraulically connecting the input chamber to the output chamber, the conduit including a check valve that permits fluid flow only from the input chamber to the output chamber,wherein a maximum volume of the input chamber is greater than a maximum volume of the output chamber.