Abstract: A brake booster (10) for a vehicle brake system comprises a housing (12) which is divided, by means of at least one movable wall (14), into a vacuum chamber (18) and a working chamber (16). A control valve arrangement (20), which is associated to the brake booster (10) and which optionally connects the working chamber (16) to atmospheric pressure or to a vacuum, comprises a control valve housing (21) which is connected to the movable wall (14) for joint relative movement with respect to the housing (12). An electromagnetic actuation unit (26) is received in the control valve housing (21), said actuation unit having a solenoid coil (44), a magnet armature (28) operating against the spring bias and which is rigidly coupled to a first valve seat (32) of the control valve arrangement (20), and an armature counter-element (46). For improving the magnetic flux in the electromagnetic actuation unit (26) while simultaneously reducing the number of parts, an insert (92) made of diamagnetic and preferably lightweight.

Abstract: A pneumatic brake booster with a booster housing part includes a vacuum chamber and a working chamber separated therefrom by a movable wall, and a valve body part including a control valve assembly and an electromagnet assembly. The control valve assembly can be actuated both by an actuation rod as well as by the electromagnet assembly, in order to make connections between the vacuum chamber and the working chamber, or between the working chamber and the ambient atmosphere. To improve the heat dissipation and to simplify the assembly the valve body part comprises several separate portions at least the first portion of the valve body part being at least partially designed as a magnetic return of the electromagnet assembly and is coupled with the second portion of the valve body part.