Electromechanical brake power assist unit

An electromechanical brake power assist unit for a vehicle braking system, comprising:

• a master brake cylinder having a piston rod;
• a brake pedal by which the piston rod is displaceable in order to build-up or reduce brake pressure, the brake pedal being pivotably suspended about an axis of rotation;
• a single electric motor by which the piston rod is also displaceable, the electric motor being activated as a function of a pedal path or a pivot angle of the brake pedal such that work applied by a driver to the brake pedal for the build-up of the brake pressure is less than work required without assistance by the electric motor for corresponding displacement of the piston rod;
• a pedal lever on which the piston rod is supported, the pedal lever being pivotable about an axis of rotation via the brake pedal,
• an auxiliary support provided at the pedal lever and/or at the piston rod, wherein
• the axis of rotation of the pedal lever is displaceable via the one electric motor substantially in a displacement direction of the piston rod of the master brake cylinder, and
• in an event of the failure of the electric motor or a linkage of the electric motor for displacing the pedal lever axis of rotation, the piston rod is supported on the pedal lever between the supporting point of the piston rod and the driver force introduction point upon a corresponding pivoting movement of the pedal lever.