VACUUM-POWERED BRAKE SERVO WITH MECHANICAL EMERGENCY BRAKING ASSISTANCE

摘要

In order to improve the braking force support in emergency braking operations, an armature (18) which co-operates with a permanent magnet (19) is provided in the control valve housing (7) of a vacuum-powered brake servo. Said armature is coupled to the actuating member (8) in the direction of actuation. The armature (18) is prestressed in an elastic manner against the direction of actuation and is held at a first distance from the permanent magnet (19) whilst the control valve (6) is in the initial position. In the course of an emergency braking operation, the armature (18) approaches the permanent magnet (19) and as soon as the distance between said armature and the permanent magnet falls short of a second predetermined distance which is less than the first distance, the armature is drawn by the permanent magnet against the elastic prestressing force acting upon said armature (18) into position against the permanent magnet (19), disconnecting the rigid coupling in the direction of actuation to the actuating member (8). In order to adjust the distance between the armature (18) and the permanent magnet (19) of the vacuum-powered brake servo (1) in its inactive state, the axial position of the permanent magnet (19) in relation to the control valve housing (7) and/or the distance between the armature (18) and the valve seat (10) can be set.