Electronically Controllable Brake Booster

Electronically controllable brake booster with a vacuum chamber and a pressure chamber, which are separated from one another by a moveable wall, a control valve arrangement, which can be actuated by means of an electromagnetic actuating device and via which a pressure difference between the pressure and the vacuum chamber can be set, wherein the control valve arrangement takes up a holding position, a pressure build-up position, a pressure reduction position in accordance with a current generated as correcting variable by an electronic control unit and flowing through the electromagnetic actuating device, a cylinder-piston arrangement, which is connected to the brake booster and comprises a piston, coupled to a brake pedal, of a hydraulic cylinder which has a hydraulic connection leading to a wheel brake, a sensor arrangement for detecting a signal which is correlated with the pressure of the hydraulic cylinder and which reproduces the controlled variable, wherein the electronic control unit establishes a command variable, taking account of the output signal of a sensor arrangement detecting the driver's braking requirement, and wherein the value of the correcting variable remains unchanged with respect to a value output directly beforehand if the control difference established from the command variable and the controlled variable does not deviate from a first predetermined tolerance range value.