Patent ID: 7051640
Filing Date: 2006-05-30
Classification: B60T

Abstract:
1. A pneumatic brake booster comprising a casing ( 4 ) of longitudinal axis (X) formed by first and second shells ( 84 , 86 ) connected by their radially external ends, in which casing a skirt ( 10 ) of longitudinal axis (X) is slidably mounted with sealing, said skirt dividing the interior space of the casing ( 4 ) into a low-pressure front chamber ( 6 ) and into a variable-pressure rear chamber ( 8 ), a pneumatic piston ( 16 ) of longitudinal axis mounted in a central orifice ( 12 ) in said skirt ( 16 ), a return spring ( 101 ) for returning the pneumatic piston to the rest position being mounted in the low-pressure chamber ( 6 ) between the first shell ( 84 ) and an annular plate ( 100 ) which is arranged in the low-pressure chamber substantially perpendicularly to the longitudinal axis and is connected rigidly to the pneumatic piston ( 16 ) by axial arms ( 96 ) passing through the skirt ( 10 ), a three-way valve actuated by a control rod ( 2 ) that is mounted in a longitudinal passage ( 24 ) bored into the pneumatic piston ( 16 ), said control rod being connected by a first longitudinal end to a brake pedal and a second end ( 50 ) of said control rod being received in a receiving cavity ( 52 ) in a first longitudinal end ( 42 ) of a plunger ( 44 ), a second longitudinal end of the plunger opposite the first end ( 42 ) of the plunger is guided in the pneumatic piston, said plunger comprising a transverse surface ( 56 ) for applying the force of the control rod to a piston of a master cylinder by way of a reaction device (DH, DHR), said skirt ( 10 ) slides axially relative to the pneumatic piston ( 16 ) over a defined travel (C) in a first phase of a braking action, said skirt ( 10 ) transmitting a pneumatic boost force to the hydraulic piston of the master cylinder via its central part, characterized in that when the skirt has completed said defined travel (C), said skirt takes the pneumatic piston ( 16 ) along with it by way of said annular plate ( 100 ).