Pneumatic brake booster comprising improved sealing means

摘要

A pneumatic brake booster comprising an envelope (101) of longitudinal axis (Y) formed of a dish (105) having a rim (153) and a lid (103). The envelop (101) defining an interior volume (107) that is divided into a variable-pressure work chamber (109) and a low-pressure chamber (111) by a skirt (113). The skirt (113) is mounted to sealingly slide along the longitudinal axis (Y) of the envelope (107). The skirt (113) has a central orifice (115) with a pneumatic piston (117) sealingly mounted therein. A three-way valve (123) is mounted in the pneumatic piston (117) and is actuated by an actuating rod (125) connected to a brake pedal. The booster is characterized in that the sealing between the variable-pressure work chamber (109) and the low-pressure chamber (111) is achieved by a first sealing member (156) arranged between a radially internal first end of the skirt (113) and a radially external end of the piston (117) and a second sealing member (157) arranged at a radially external second end of the skirt (113) and an internal surface of the rim (153). The skirt (113) provides sealing between the radially external first end of the skirt and the radially internal second end of the skirt.