Hydraulic brake system for automotive vehicles comprising a traction slip control means

Claim 1

A hydraulic brake system for an automotive vehicle including a means for controlling traction slip comprising wheel sensors, a master brake cylinder (1), a pedal operated servo system (3) for actuating the master brake cylinder (1), wheel brake cylinders on driven wheels of the vehicle which are in communication with the master brake cylinder (1), through brake conduits (62, 63), sensors (S1, S2, S3, S4) for determining angular speed of the wheels, and an electronic analyzer (28) evaluating the sensor signals and generating switch signals for inlet and outlet valves, with the inlet valves (24, 25, 29, 30) being provided in the brake conduits and the outlet valves (22, 23, 35, 36) being provided in a relief conduit (37) between the wheel brake cylinders and a pressure fluid reservoir, and pumps (21, 26) having intake sides which are respectively in communication with the brake conduits (62, 63), wherein a booster chamber (84) of the servor system is placed in communication with a pressure source through an ASR control valve (80), irrespective of positions of the pedal (5), and wherein the electronic analyzer (28) generates switching signals for operating said control valve (80) and said pumps (21, 26) upon detection, through the sensor signals, that one of the driven wheels tends to spin, and wherein upon detection of the driven wheel tending to spin, said pumps (21, 26) are activated and said control valve (80) is switched causing air pressure to be applied to said booster chamber (84) of said servo system (3) wherein said master cylinder (1) is actuated independently of actuation of the pedal (5) and wherein during an initial start-up phase of said pumps (21, 26) pressure fluid is transmitted from the master brake cylinder to the driven wheels to prevent the wheels from spinning during the start-up phase of said pumps 21, 26).