Pneumatischer Bremskraftverstärker mit mechanischer und elektromagnetischer Betätigung

摘要

The invention relates to a pneumatic power brake booster which has a power booster housing (10) whose inner area is divided into a low pressure chamber (14) and a working chamber (16) by at least one moveable wall (12). A control valve (18) projects into the power booster housing (10) along an axis (A) in order to control a pneumatic pressure difference acting upon the moveable wall (12). The control valve (18) has a control valve housing (20) to which the moveable wall (12) is connected in a force transmitting manner. The control valve (18) can be actuated by a mechanical input element (24) and by an electromagnetic configuration (48) independently of one another. The housing (52, 54) of the electromagnetic configuration (48) can be axially displaced in the control valve housing (20) and has a first active surface (W1) which is arranged perpendicular to the axis (A) and is subjected to the pressure in the low pressure chamber (14) during operation. The housing also has a second active surface (W2) situated opposite the first active surface (W1) which is also arranged perpendicular to the axis (A) and is subjected to the pressure in the working chamber (16) during operation. As a result, a feedback of the pressure difference existing on the moveable wall (12) occurs on the electromagnetic configuration (48) which permits a defined difference pressure to be assigned to each drive current.