Skid-controlled hydraulic brake system

Claim 1

A hydraulic skid-controlled brake system for use with motor vehicles comprising a master cylinder (2) having a master cylinder piston and being pressurizable by a hydraulic force booster (1) having a booster piston, wherein valve means (24, 29, 42 and 23, 28, 39 and 43, respectively) are provided between the master cylinder (2) and the wheel brakes (25, 30, 40, 41) connected to the master cylinder through which pressure fluid is discharged from the wheel brakes (25, 30, 40, 41), with pressure fluid discharged from the wheel brakes being reloadable from the pressure chamber (10) of the hydraulic force booster (1) and wherein, during slip control, the stroke of the brake pedal (8) is limited, wherein an annular chamber (19) is disposed between the booster piston (4) and the master cylinder piston (5) which annular chamber is traversed by a small step (14) facing the booster piston (4) of the master cylinder (5) formed as a stepped piston, and in which annular chamber a large step of the master cylinder piston (5) is sealingly guided, with the annular chamber (19) being in communication, by way of a pressure fluid conduit (18, 21, 22) in which a valve (26) is provided with a working chamber (16) of the master cylinder (2), and with the cylinder wall of the annular chamber (19) being provided with a connector (33) which, upon movement of the master cylinder piston (5) in the actuating direction is opened by the latter, and which is in communication with the intake reservoir (11) by way of a pressure fluid conduit (34, 47, 36) in which a blockable current control valve (35) is provided, the valve (26) provided in the pressure fluid conduit (18, 21, 22) leading from the annular chamber (19) to the working chamber (16) of the master cylinder (2) is a 2-way/2-position valve which is controlled by the pressure in a main conduit (49) connected to a main valve (43), with said 2-way/2-position valve (26) taking its blocking position when, during the skid control, the main valve (43) opens a passage for the controlled pressure from the pressure chamber (10) of the hydraulic force booster (1) to the main conduit (49), the current control valve (35) comprises a blocking piston (57) which is supported by a control piston (63) to which the controlled pressure of the force booster (1) is applied and which, during the skid control, takes its opening position thereby permitting the passage of the pressure fluid through an aperture (59) of the current control valve (35).