Patent ID: 7390174

Claim:
A piston pump ( 10 ) for supplying pressure fluid into a hydraulic consumer of an electronically controlled vehicle brake system, comprising a stepped piston ( 50 , 50 ′) which is arranged in a stepped bore ( 39 , 40 ) of an accommodating member ( 3 ) so as to be movable within a bushing ( 18 , 19 ) in an axial direction Ax, the stepped piston ( 50 , 50 ′) being partly designed like a hollow tube at least at one end ( 51 , 51 ′), a displacement chamber ( 24 , 25 ) being limited by the end ( 50 , 50 ′) of the stepped piston ( 50 , 50 ′) and having a stepped design at its outside periphery, and carrying and centering a sealing assembly ( 26 , 26 ′) which is retained in the axial direction Ax by a step ( 52 , 52 ′) on the stepped piston ( 50 , 50 ′), on the one hand, and is retained by a spring cage ( 53 , 53 ′), on the other hand, the stepped piston ( 50 , 50 ′) including radially inwards with respect to the sealing assembly ( 26 , 26 ′) a plane support ( 54 , 54 ′) for plane support legs ( 55 a,b,c ; 55 a,b,c ′) of the spring cage ( 53 , 53 ′), the plane support ( 54 , 54 ′) being provided orthogonally to the axial direction Ax, the stepped piston ( 50 , 50 ′) including radially inwards, with respect to the support ( 54 , 54 ′), a stepped bore ( 56 , 56 ′), with the bore ( 56 , 56 ′) accommodating centering legs ( 57 a,b,c ; 57 a,b,c ′) of the spring cage ( 53 , 53 ′), a spring-loaded valve member ( 59 , 59 ′) of a non-return valve being arranged coaxially inside the stepped bore ( 56 , 56 ′), which valve member serves to ventilate the displacement chamber ( 24 , 25 ), a resetting spring ( 38 ) being arranged in the displacement chamber ( 24 , 25 ) and supported on an abutment ( 41 ) of the bushing ( 18 , 19 ), on the one hand, and on the spring cage ( 53 , 53 ′), on the other hand, the bushing ( 18 , 19 ) being provided at one end with a stop ( 63 , 63 ′) for the stepped piston ( 50 , 50 ′), said stop ( 63 , 63 ′) in a radial direction R being smaller than the diameter of the stepped piston ( 50 , 50 ′), while at the opposite end of the bushing ( 18 , 19 ) at least one abutment ( 41 ) for the resetting spring ( 38 ) is attached so that stepped piston ( 50 , 50 ′), resetting spring ( 38 ), non-return valve and sealing assembly ( 26 ) are arranged within the bushing ( 18 , 19 ) as a subassembly that can be handled independently.