Electrohydraulic brake system for motor vehicles

An electrohydraulic brake system for a motor vehicle which can be operated in a ‘brake-by-wire’ mode of operation, comprising:

• a master cylinder (1) connectable to wheel brake cylinders;
• a first piston (2) coupled to a brake pedal (3),
• a second piston (4) for actuating the master cylinder (1),
• a third piston (5) which can be operated by the first piston (2), with at least one brake pedal characteristics simulation device (6, 7) for exerting a simulator force being provided between the first (2) and the third piston (5) and imparting a comfortable pedal feel to an operator in a by-wire mode of operation, wherein the first piston, the second piston, the third piston and the travel simulator device are arranged in a housing (8),
• a hydraulic pressure source (9);
• and
• a valve device (10) operable by the third piston (5) for reducing a pressure of the pressure source (9) to a value used for application of the second piston (4), wherein the second (4) and the third piston (5) are isolated from each other by a space (11) so that the third piston (5) is acted upon by the pressure that acts on the second piston (4) in a direction opposite to a direction of application of the second piston (4);
• and
• a valve member (13) of the valve device has both end surfaces exposed to an effect of the pressure that prevails in the space (11).