Brake-by-wire system including pressure balanced PSU piston with wetted ball screw

Abstract

An electro-hydraulic brake system comprises a single-circuit master cylinder (MC) fluidly coupled to a first MC fluid passageway and configured to supply fluid into the first MC fluid passageway in response to pressing force on a brake pedal coupled thereto. The electro-hydraulic brake system also comprises a pressure supply unit (PSU) assembly including an electric motor coupled to a ball screw actuator, a PSU housing defining a piston bore having a terminal end opposite the electric motor, and a PSU piston disposed within the piston bore and movable by the ball screw actuator through the piston bore and dividing the piston bore into a first chamber and a second chamber, with each of the first chamber and the second chamber containing a hydraulic fluid. The ball screw actuator includes an actuator nut assembly having a plurality of ball bearings each disposed within the piston bore and submerged in the hydraulic fluid.

Dependencies are inferred from the claim text.