Actuating Unit for a Motor Vehicle Brake System

An activation unit for a motor vehicle brake system of a “brake-by-wire” type, having:

• a) a brake booster which is configured to be activated either by a brake pedal or as a function of a driver's request or independently of the driver by an electronic control unit, with a mechanism to permit decoupling of a force-transmitting connection between the brake pedal and brake booster in a “brake-by-wire” operating mode being provided between the brake pedal and the brake booster,
• b) a master brake cylinder which is connected downstream of the brake booster,
• c) means for sensing a driver's request or an activation travel of the brake pedal,
• d) a pedal travel simulator which interacts with the brake pedal and by means of which a restoring force which acts on the brake pedal in the “brake-by-wire” operating mode can be simulated independently of activation of the brake booster, and
• e) a hydraulic activation and deactivation device which activates the pedal travel simulator in the “brake-by-wire” operating mode and deactivates the pedal travel simulator outside of the “brake-by-wire” operating mode, and which is formed by a cylinder-piston arrangement whose pressure space is connected by a disconnectable connection to a pressure medium volume accommodating element and on whose piston a simulator housing is supported via a piston rod, wherein a connection having three degrees of freedom is provided between the piston and the piston rod.