Piston pump

Abstract

The invention relates to a piston pump ( 10 ) for a hydraulic vehicle brake system that has traction control. The invention proposes embodying the piston pump ( 10 ) with a piston ring ( 24 ), for instance a PTFE, which ring serves as both a sealing and a guide ring. The invention lessens the effort and expense of assembly as well as the production costs for the piston pump ( 10 ). To achieve reliable sealing, the invention proposes embodying the piston ring ( 24 ) with an internal cone on its side toward a pump chamber ( 18 ), so that during a pumping stroke, the piston ring ( 24 ) is subjected to pressure from the pump chamber ( 18 ) and is pressed into sealing contact against a pump bore ( 12 ).

1 . A piston pump, having a pump piston, which is drivable to execute an axially reciprocating stroke motion in a pump housing, and which in its stroke motion alternatingly increases (reverse stroke) and decreases (pumping stroke) a volume of a pump chamber, which pump chamber is an axial portion of the pump bore and is defined on one side by the pump piston, and having a piston ring, which is disposed on an end, toward the pump chamber, of the pump piston, characterized in that the piston ring ( 24 ) forms a sealing and guide ring that is not loaded in the axial direction and that in any case during the pumping stroke seals off the pump piston ( 16 ) in the pump bore ( 12 ), and which ring guides the pump piston ( 16 ) axially displaceably in the pump bore ( 12 ).  
     
     
         2 . The piston pump of  claim 1 , characterized in that the piston ring ( 24 ), in an axial portion, has a circumferential face ( 100 ) that is subjected to fluid from the pump chamber ( 18 ), and the circumferential face ( 100 ) faces away from a counterpart face ( 96 ) on which the piston ring ( 24 ) rests sealingly and relative to which the piston ring ( 24 ) is displaced during the stroke motion of the pump piston ( 16 ).  
     
     
         3 . The piston pump of  claim 2 , characterized in that the piston ring ( 24 ) has a diameter change, which brings about the subjection of the circumferential face ( 100 ) of the piston ring ( 24 ), in the axial portion of the piston ring ( 24 ), to fluid from the pump chamber ( 18 ).  
     
     
         4 . The piston pump of  claim 3 , characterized in that the piston ring ( 24 ) has a conical face, on its side toward the pump chamber ( 18 ).  
     
     
         5 . The piston pump of  claim 3 , characterized in that the piston ring ( 24 ) has an annular step as a diameter change.  
     
     
         6 . The piston pump of  claim 3 , characterized in that the piston ring ( 24 ) is symmetrical to a radial center plane.  
     
     
         7 . The piston pump of  claim 1 , characterized in that the piston ring ( 24 ) rests with initial tension on the pump piston ( 18 ).  
     
     
         8 . The piston pump of  claim 1 , characterized in that the piston ring ( 24 ) rests with initial tension in the pump bore ( 12 ).  
     
     
         9 . The piston pump of  claim 1 , characterized in that the piston ring ( 24 ) has a free face ( 105 ) on its circumference, over a portion of its axial length, with which face it does not rest on a counterpart face ( 96 ).