Idle volume reducing means in a piston pump for a brake system of a vehicle

Abstract

A piston pump which is intended in particular for a vehicle hydraulic, slip-controlled brake system. To reduce idle volume in the piston pump, a positive-displacement body is mounted on the piston by means of a retaining part. The displacement body protrudes into an interior of a valve closing spring, embodied as a helical spring, of an inlet valve integrated with the piston. The embodiment of the valve closing spring and of a piston restoring spring with a rectangular coil cross section also contributes to reducing the idle volume of the piston pump. Reducing the idle volume increases the efficiency of the piston pump.

1 . A piston pump with a piston that can be driven to execute a reciprocating stroke motion, and with a positive-displacement chamber whose volume is decreased and increased in the stroke motion of the piston, characterized in that the piston pump ( 10 ;  34 ;  120 ) has a positive-displacement body ( 32 ;  104 ), which is disposed in the positive-displacement chamber ( 2 ;  106 ).  
     
     
         2 . The piston pump according to    claim 1   , characterized in that the piston pump ( 10 ;  34 ;  120 ) has a helical spring ( 24 ;  74 ,  92 ), in whose interior the positive-displacement body ( 32 ;  104 ) is disposed.  
     
     
         3 . The piston pump according to    claim 2   , characterized in that the helical spring ( 24 ;  74 ,  92 ) has spring coils whose coil faces toward one another are substantially complementary to one another.  
     
     
         4 . The piston pump according to    claim 3   , characterized in that the spring coils have a rectangular cross section.  
     
     
         5 . The piston pump according to    claim 2   , characterized in that a helical spring is a piston restoring spring ( 24 ;  74 ).  
     
     
         6 . The piston pump according to    claim 2   , characterized in that the piston pump has a check valve ( 18 ), and that the helical spring is a valve closing spring ( 92 ) of the check valve ( 88 ).  
     
     
         7 . The piston pump according to    claim 1   , characterized in that the piston ( 66 ) has a check valve ( 88 ), whose valve closing body ( 19 ) is held on the piston ( 66 ) by a retaining part ( 98 ) mounted on the piston ( 66 ), and that the retaining part ( 98 ) has a positive-displacement body ( 104 ).  
     
     
         8 . The piston pump according to    claim 7   , characterized in that the positive-displacement body ( 104 ) defines an opening stroke of the valve closing body ( 90 ).  
     
     
         9 . The piston pump according to    claim 5    or    6   , characterized in that the retaining part ( 98 ) centers the helical spring ( 74 ,  92 ).  
     
     
         10 . The piston pump according to one of claims  7 - 9 , characterized in that the retaining part ( 98 ) has a centering device ( 108 ), which engages a hole ( 84 ) in the piston ( 66 ) and aligns the retaining part ( 98 ) on the piston ( 66 ).  
     
     
         11 . The piston pump according to    claim 10   , characterized in that the retaining part ( 98 ), via its centering device ( 108 ), is connected to the piston ( 66 ) by nonpositive, positive, and/or material engagement.  
     
     
         12 . The piston pump according to    claim 7   , characterized in that the ( 98 ) is embodied as a guide element, which guides the piston ( 66 ) in a cylinder bore of the piston pump ( 34 ).  
     
     
         13 . The piston pump according to    claim 7   , characterized in that the retaining part ( 98 ) is embodied as a sealing element, which seals off the piston ( 66 ) at a wall of the cylinder bore.  
     
     
         14 . The piston pump according to    claim 7   , characterized in that the retaining part ( 98 ) is a plastic part.