High-pressure fuel pump

Abstract

A high-pressure fuel pump apparatus may include a housing, a camshaft that may be mounted in the housing and rotated by operation of an engine, an eccentric cam that may be disposed eccentrically with respect to the camshaft and integrally rotated with the camshaft, a piston that may be slidably mounted in the housing and engaged to the eccentric cam to move up/down in the housing to produce a pressured fuel with rotation of the eccentric cam, and a rotary member that may be disposed between the eccentric cam and the piston and has a rolling contact with the eccentric cam and the piston to convert rotation of the eccentric cam into a straight motion of the piston.

What is claimed is: 
     
         1 . A high-pressure fuel pump apparatus comprising:
 a housing;   a camshaft that is mounted in the housing and rotated by operation of an engine;   an eccentric cam that is disposed eccentrically with respect to the camshaft and integrally rotated with the camshaft;   a piston that is slidably mounted in the housing and engaged to the eccentric cam to move up/down in the housing to produce a pressured fuel with rotation of the eccentric cam; and   a rotary member that is disposed between the eccentric cam and the piston and has a rolling contact with the eccentric cam and the piston to convert rotation of the eccentric cam into a straight motion of the piston.   
     
     
         2 . The high-pressure fuel pump apparatus of  claim 1 ,
 wherein the rotary member is positioned inside the piston, and   wherein a portion of the rotary member protrudes from the piston to have the rolling contact with the eccentric cam.   
     
     
         3 . The high-pressure fuel pump apparatus of  claim 2 , wherein the piston is spaced with the eccentric cam by the rotary member to prevent direct contact between the eccentric cam and the piston. 
     
     
         4 . The high-pressure fuel pump apparatus of  claim 1 , wherein a guide groove is formed along an outer circumferential surface of the eccentric cam and receives the rotary member therein to guide rotation of the rotary member. 
     
     
         5 . The high-pressure fuel pump apparatus of  claim 1 , further including an elastic member that provides an elastic force to the piston toward the camshaft. 
     
     
         6 . The high-pressure fuel pump apparatus of  claim 1 , wherein the piston further has:
 a support portion having a large diameter in comparison to an other portion thereof and having a lower portion formed in a hollow cylindrical shape; and   a connector selectively fastened to the lower portion of the support portion,   wherein the support portion and the connector are combined such that the rotary member is positioned inside the lower portion of the piston.   
     
     
         7 . The high-pressure fuel pump apparatus of  claim 6 ,
 wherein a rotary member insertion hole is vertically formed through the connector,   wherein a rotary member seat groove is formed in the support portion such that the rotary member is slidably seated thereon, and   wherein the rotary member is disposed inside the piston while slidably covered by the rotary member insertion hole and the rotary member seat groove.   
     
     
         8 . The high-pressure fuel pump apparatus of  claim 7 , wherein a diameter of the rotary member is larger than a diameter of the rotary member insertion hole such that the rotary member is prevented from being separated from the piston. 
     
     
         9 . The high-pressure fuel pump apparatus of  claim 8 , wherein a portion of the rotary member protrudes down from the rotary member insertion hole to have the rolling contact with the eccentric cam. 
     
     
         10 . The high-pressure fuel pump apparatus of  claim 6 , wherein the connector is thread-fastened to the support portion. 
     
     
         11 . The high-pressure fuel pump apparatus of  claim 1 , wherein the rotary member has a ball shape. 
     
     
         12 . The high-pressure fuel pump apparatus of  claim 1 ,
 wherein the housing includes a hydraulic chamber into which the piston is slidably disposed, and   wherein a first pressure channel receiving a first pressured fluid and a second pressure channel supplying the pressured fluid to an injector are fluid-connected to the hydraulic chamber.