Patent ID: 7255036

Claim:
A pneumatic servomotor ( 12 ) for assisted braking comprising a rigid axial casing ( 16 ), in which a substantially truncated-cone shaped transverse skirt ( 18 ) is movable and integral with a piston ( 20 ) for the actuation of an associated master cylinder ( 14 ), said skirt defining two pressure chambers ( 24 , 26 ) inside the casing in which a substantially annular sealing diaphragm ( 30 ) made of an elastomeric material is interposed between the casing ( 16 ) and an outer peripheral area ( 32 ) of the skirt ( 18 ); and in which a substantially annular seal ( 34 ) made of an elastomeric material is interposed between an inner area ( 36 ) of the skirt ( 18 ) and the piston ( 20 ), characterized in that the sealing diaphragm ( 30 ) and/or the seal ( 34 ) comprise(s) a portion, which is moulded over the skirt ( 18 ), said portion including an annular portion ( 44 ) of the diaphragm ( 30 ), that faces the axis of the servomotor ( 12 ), covers both sides ( 31 , 33 ) of an outer peripheral truncated-cone shaped area ( 32 ) of the skirt ( 18 ), and fills at least a first through thickness channel ( 46 ) provided in said outer peripheral area ( 32 ) of the skirt ( 18 ), so as to ensure a continuity of the elastomeric material of the diaphragm ( 30 ), said channel ( 46 ) is situated facing a projection ( 48 ), formed in the outer peripheral truncated-cone shaped area ( 32 ) of the skirt ( 18 ), creating an accumulation area ( 49 ) for the elastomeric material of the diaphragm ( 30 ) to provide more reliable strength of said elastomeric material close to the channel ( 46 ).