Radial piston pump for providing high pressure in fuel injection systems of internal combustion engines

Abstract

The invention relates to a radial piston pump ( 1 ) for high-pressure fuel generation in fuel injection systems of internal combustion engines, in particular in a common rail injection system, having a drive shaft ( 4 ) which is mounted in a pump casing ( 2 ) and has an eccentric shaft section ( 6 ) on which a running roller ( 8 ) is mounted, and having preferably a plurality of pistons ( 16 ), which are arranged in a respective cylinder ( 14 ) radially with respect to the drive shaft ( 4 ) and each have a piston footplate ( 18 ), which makes contact with the circumferential surface ( 10, 12 ) of the running roller ( 8 ), at their ends facing the running roller ( 8 ). The invention provides that at least that surface ( 28 ) of the piston footplate ( 18 ) which is in contact with the circumferential surface ( 10, 12 ) of the running roller ( 8 ) consists of a wear-resistant material, namely of hard metal, a ceramic material, a cast carbide material, or cermet.

1 - 8 . (canceled)  
     
     
         9 . A radial piston pump ( 1 ) for high-pressure fuel generation in fuel injection systems of internal combustion engines, in particular in a common rail injection system, having a drive shaft ( 4 ) which is mounted in a pump casing ( 2 ) and has an eccentric shaft section ( 6 ) on which a running roller ( 8 ) is mounted, and having preferably a plurality of pistons ( 16 ), which are arranged in a respective cylinder ( 14 ) radially with respect to the drive shaft ( 4 ) and each have a piston footplate ( 18 ), which makes contact with the circumferential surface ( 10 ,  12 ) of the running roller ( 8 ), at their ends facing the running roller ( 8 ), wherein at least that surface ( 28 ,  31 ) of the piston footplate ( 18 ) which is in contact with the circumferential surface ( 10 ,  12 ) of the running roller ( 8 ) consists of hard metal, a cast carbide material, or cermet.  
     
     
         10 . The radial piston pump as claimed in  claim 9 , wherein the piston footplate ( 18 ), on its surface ( 31 ) facing the running roller ( 8 ), bears at least one insert ( 30 ) made from hard metal, from a cast carbide material or from cermet.  
     
     
         11 . The radial piston pump as claimed in  claim 9 , wherein the hard metal contains G20, GC37 or GC20 and has a surface roughness R z  of between 0.3 μm and 1.0 μm.  
     
     
         12 . The radial piston pump as claimed in  claim 9 , wherein the cast carbide material contains a chilled cast iron material, in particular GGH or SoGGH, and has a surface roughness R z  of between 0.5 μm and 2.0 μm.  
     
     
         13 . The radial piston pump as claimed in  claim 9 , wherein the piston footplate ( 18 ), on its surface ( 31 ) facing the running roller ( 8 ), has at least two grooves ( 50 ) which cross one another.  
     
     
         14 . The radial piston pump as claimed in  claim 13 , wherein one such groove ( 50 ) is in each case arranged in the center of a depression ( 39 ), forming a groove run-out, in the surface ( 31 ).  
     
     
         15 . The radial piston pump as claimed in  claim 9 , wherein the surface of the piston footplate ( 18 ) and/or of the running roller ( 8 ) has a surface roughness R z  of between 0.15 μm and 2 μm.