Patent ID: 7673554

Claim:
Tie rod-type pneumatic brake booster ( 10 ) for a motor vehicle, of the type which comprises a rigid casing ( 12 ) of axial orientation (A) inside which is movably mounted a substantially transverse partition ( 14 ) sealingly delimiting a front chamber ( 16 ), subjected to a first pressure (P 1 ), and a rear chamber ( 18 ), subjected to a second pressure (P 2 ) varying between the first pressure (P 1 ) and a pressure (P a ) above the first pressure (P 1 ), which is able to act on an actuating rod ( 20 ) of a master cylinder associated with the booster ( 10 ), and the movements of which are controlled by intake and equalizing valves for varying the second pressure (P 2 ) in the rear chamber ( 18 ), of the type in which the moving partition ( 14 ) comprises at least one cup ( 38 ) of which at least an annular portion ( 39 ) is inclined by a defined angle (α) with respect to the axial direction (A) of the casing ( 12 ), and of which a defined face ( 40 ) is covered by a sealing diaphragm ( 42 ) connected to the inner periphery of the casing ( 12 ), of the type in which the booster ( 10 ) is intended to be fastened to a bulkhead ( 34 ) of an associated vehicle by way of tie rods ( 24 ) of axial orientation passing through the casing ( 12 ) of the booster ( 10 ) and through the annular portion ( 39 ) of the moving partition ( 14 ), and of the type in which the cup ( 38 ) has an aperture ( 46 ) associated with each tie rod ( 24 ) that accommodates a sealing ring ( 48 ) which is, on the one hand, fastened to the cup ( 38 ) and which is, on the other hand, slideably mounted on the associated tie rod ( 24 ), characterized in that the cup ( 38 ) comprises, in its inclined annular portion ( 39 ), a tubular element ( 50 ) which contains the aperture ( 46 ) and which extends at least axially in part around the sealing ring ( 48 ) so as to ensure more uniform distribution of the pressures around the sealing ring ( 48 ) and limit the deformations of said ring ( 48 ) when it is subjected to a pressure difference between the front chamber ( 16 ) and rear chamber ( 18 ) of the booster ( 10 ), characterized in that the sealing ring ( 48 ) is integrally formed with the sealing diaphragm ( 42 ), and characterized in that the sealing ring ( 48 ) comprises an end portion ( 52 ), with a diameter (D) greater than the inside diameter (d) of the tubular element ( 50 ), which is intended to be inserted with deformation into the aperture ( 46 ) in the tubular element ( 50 ) from the side toward the defined face ( 40 ) of the cup ( 38 ) and then to project from the tubular element ( 50 ) on the side opposed to the defined face ( 40 ) in order to axially immobilize the sealing ring ( 48 ).