Patent ID: 7950320

Claim:
A brake booster for motor vehicles comprising: a booster housing ( 1 ) having an interior space which is subdivided by a movable wall ( 2 ) into a low-pressure chamber ( 4 ) and a working chamber ( 3 ), and with a control housing ( 5 ) that carries the movable wall ( 2 ), in which a control valve ( 12 ) is arranged which controls a pneumatic pressure difference acting on the movable wall ( 2 ) and is operable both by an actuating rod ( 7 ) by means of a valve piston ( 9 ) and, irrespective of the actuating rod ( 7 ), by an electromagnet ( 20 ), the control valve having three sealing seats ( 15 , 16 , 24 ) which are arranged concentrically to one another and of a valve body ( 10 ), which cooperates with the sealing seats ( 15 , 16 , 24 ) and is furnished with axial passages ( 19 ), with the first sealing seat ( 15 ) being provided in the control housing ( 5 ) and the second sealing seat ( 16 ) being provided on the valve piston ( 9 ), while the third sealing seat ( 24 ) is provided on a sleeve ( 32 ) that cooperates with the electromagnet ( 20 ), and with a ring ( 36 ) arranged displaceably in relation to the third sealing seat ( 24 ), said ring being supported on the sleeve ( 32 ) by the intermediary of an elastic or compressible element ( 37 ), a fringe area of the element close to the valve body ( 10 ) including areas ( 33 ) that are separated by radial apertures ( 39 ) through which it is in contact with the valve body ( 10 ), and which is arranged in the release position axially offset towards the valve body ( 10 ) with regard to the third sealing seat ( 24 ), wherein the ring ( 36 ) is arranged radially within the sleeve ( 32 ) in such a manner that its areas ( 33 ), by which it is in contact with the valve body ( 10 ), at least partly release the passages ( 19 ) provided in the valve body ( 10 ).