Patent ID: 6711983
Filing Date: 2004-03-30
Classification: B60T

Abstract:
A vacuum brake booster comprisinga vacuum chamber and a working chamber, which is separated in a pressure-tight manner from the latter by a mobile wall, and a control valve, which comprises a housing coupled in a force-transmitting manner to the mobile wall and a first valve seat, which is disposed in the housing and which, in co-operation with a first valve sealing member, controls the supply of atmospheric pressure or pressure above atomspheric to the working chamber in accordance with the displacement of an input member, which is coupled to the first valve seat, of the brake booster in order to obtain a pressure difference at the mobile wall, wherein the first valve seat is formed at a displaceable valve member which is coupled to the input member in the actuating direction of the brake booster and comprises a second valve seat which, in co-operation with the first valve sealing member, controls a connection between the vacuum chamber and the working chamber, wherein the valve member is subjected to the pressure prevailing in the working chamber at its rear side, which is turned towards the input member, after the displaceable valve member has exceeded a prefixed displacement in the actuating direction relative to the control valve housing, the valve member is subjected over at least a part of its front side, which lies opposite the rear side, to the pressure prevailing in the vacuum chamber, wherein the pressure difference then acting on the displaceable valve member to hold it in the position which is reached until pressure equalization between the front side and the rear side of the displaceable valve member takes place, and that a component which is coupled to the input member in the direction opposite to the actuating direction of the brake booster acts on the first valve sealing member and lifts it off the second valve seat after a prefixed displacement of the input member opposite to the actuating direction.