Piston pump for a brake system for a vehicle

Abstract

A piston pump for a hydraulic slip-controlled brake system for a vehicle. To seal off and guide a piston of the piston pump in a bush, the piston pump includes a seal of rigid plastic which has a spreader face in the form of an internal cone. A piston restoring spring presses directly or indirectly against the spreader face via a spreader ring with a conical counterpart face and thereby presses the seal into sealing contact with the bush. The piston pump has the advantage that no separate sealing ring or guide ring is needed for the piston, and that friction and wear are both only slight.

1 . A piston pump, having a piston that can be driven to execute a reciprocating stroke motion and is axially displaceably guided in a cylinder bore, and having a seal which seals at a slide face, characterized in that the seal ( 76 ) is urged radially against the slide face by a spring element ( 54 ).  
     
     
         2 . The piston pump according to    claim 1   , characterized in that the piston pump ( 10 ) has a piston restoring spring ( 54 ), which simultaneously forms the spring element.  
     
     
         3 . The piston pump according to    claim 1    or    2   , characterized in that the seal ( 76 ) serves to guide the piston ( 20 ).  
     
     
         4 . The piston pump according to one of claims  1 - 3 , characterized in that the seal ( 76 ) has a spreader face ( 80 ) with an inclination to a radial direction, and that the spring element ( 54 ) urges the spreader face ( 80 ) in the axial direction, so that the seal ( 76 ) is urged in the radial direction.  
     
     
         5 . The piston pump according to one of claims  1 - 4 , characterized in that the piston pump ( 10 ) has a counterpart face ( 84 ,  88 ) to the spreader face ( 80 ) of the seal ( 76 ), and the counterpart face ( 84 ,  88 ) is oriented toward the spreader face ( 80 ) and has an inclination to a radial direction that is oriented opposite the inclination of the spreader face ( 80 ), and that the seal ( 76 ) is pressed with its spreader face ( 80 ) against the counterpart face ( 84 ,  88 ) by the spring element ( 54 ), so that the seal ( 76 ) is urged in the radial direction.  
     
     
         6 . The piston pump according to    claim 5   , characterized in that the counterpart face ( 84 ) is formed on a ring ( 82 ).  
     
     
         7 . The piston pump according to    claim 5   , characterized in that the counterpart face ( 88 ) is formed on the piston ( 20 ).  
     
     
         8 . The piston pump according to    claim 5   , characterized in that the counterpart face ( 88 ) is formed in the cylinder bore of the pump housing ( 16 ).  
     
     
         9 . The piston pump according to    claim 1   , characterized in that the seal ( 76 ) is a plastic ring.  
     
     
         10 . The piston pump according to one of the foregoing claims, characterized in that the seal ( 76 ) is integrally formed onto the piston ( 20 ).  
     
     
         11 . The piston pump according to    claim 9   , characterized in that the seal ( 76 ) comprises PTFE (polytetrafluoroethylene).