Electrohydraulic brake system for motor vehicles

Electrohydraulic brake system for motor vehicles which is controllable in a ‘brake-by-wire’ mode of operation by the vehicle operator as well as irrespective of the vehicle operator, is preferably operated in the brake-by-wire mode of operation, and can be operated in a fallback mode of operation in which only operation by the vehicle operator is possible, including

• a master brake cylinder operable by means of a brake pedal and having at least one pressure chamber,
• a travel simulator cooperating with the master brake cylinder and having a simulator piston positioned by means of a spring, said simulator piston limiting a simulator chamber accommodating the spring, on the one hand, and a simulator chamber communicating with one of the pressure chambers of the master brake cylinder, on the other hand,
• an unpressurized pressure fluid reservoir,
• a hydraulic auxiliary pressure source,
• an electronic controlling and regulating unit, and
• wheel brakes connectable to the master brake cylinder and the hydraulic pressure source,
• characterized in that a means is provided for making available a pressure fluid volume flow that ensures in the fallback mode of operation at least the pressure fluid volume needed for the respectively required deceleration.