Abstract: A brake system for motor vehicles with an adjustable pneumatic brake force booster includes a control valve which can be actuated by an electromagnet independently of the driver's actions. A brake pressure controller generates signals which serve to actuate the electromagnet. In order to be able to implement a quick-action, low-noise pressure regulating system at low cost, the brake pressure controller (8) is formed by connecting in parallel an electromagnetic control circuit (60) that processes the nominal brake pressure signal (Pnominal) into a first current value (IA) and a regulating circuit (70) that processes a control difference (&Dgr;P) formed from the nominal brake pressure signal (Pnominal) and the actual pressure signal (Pactual) into a second current value IB, with the output variable (Inominal) of the brake pressure controller (8) being formed by adding together the two current values (IA, IB).

Abstract: The present invention discloses a brake force booster for automotive vehicles having a control valve which is operable independently of an actuating rod displacing a valve piston, by way of an electromagnet which actuates a third sealing seat. Displacement of the sealing seat in opposition to the actuating direction of the brake force booster permits ventilating the working chamber. To eliminate all pneumatically induced force components in an independent activation, according to the present invention, a permanent pneumatic connection is provided between a pneumatic chamber delimited in the control housing by the valve member and the vacuum chamber, and in that both a second sealing seat which is provided on the valve piston and used to ventilate the working chamber, the third sealing seat, and the valve member in its sealing lip delimiting the pneumatic chamber in the control housing have almost identical diameters.