Patent ID: 6233932
Filing Date: 2001-05-22
Classification: B60T

Abstract:
A fully hydraulic brake power generator/master cylinder unit for a vehicle brake system, witha housing and a bore which is formed therein and in which a primary piston is arranged sealingly and displaceably,an input member for actuating the brake power generator/master cylinder unit, said input member being displaced during actuation,a first pressure chamber which is arranged in the bore and one boundary wall of which is formed by one end wall of the primary piston,a hydraulic booster stage, acting on the primary piston, for boosting the actuating force exerted on the input member, said booster stage comprising a booster chamber with an inlet for hydraulic fluid under pressure,a spring arrangement, acting on the input member counter to an actuating force, for simulating brake pressure feedback via the input member, characterized in thatthe spring arrangement has a first spring and a second spring which are connected in series, the spring force of the second spring being detectably greater than the spring force of the first spring, and in thatwhen the brake power generator/master cylinder unit is actuated, if the hydraulic booster stage fails essentially only the force of the first spring carries out brake pressure feedback.