Valve train for internal combustion engine

Abstract

The present invention provides a valve train for an internal combustion engine, capable of preventing the minute slippage between the cam lobe and the roller follower, and thereby reducing the friction loss in the valve train system. At least one of the following measures is applied to the valve train. Measure 1: A cam lobe made of an iron sintered material is used, and the surface roughness Ra of the outer circumferential surface thereof is made to be in a range of 0.4 to 2.2 μm. Measure 2: The surface roughness Ra of the outer circumferential surface of the roller of the roller follower is made to be in a range of 0.4 to 2.2 μm.

What is claimed is:  
     
         1 . A valve train for an internal combustion engine comprising a cam lobe fixed on a cam shaft and a roller follower provided with a roller to come in rotation-contact with the cam lobe, wherein the cam lobe is made of an iron based sintered material, and the surface roughness Ra of the outer circumferential surface thereof is 0.4 to 2.2 μm.  
     
     
         2 . The valve train according to  claim 1 , wherein the surface roughness Ra of the outer circumferential surface of the roller is 0.4 to 2.2 μm.  
     
     
         3 . A valve train for an internal combustion engine comprising a cam lobe fixed on a cam shaft and a roller follower provided with a roller to come in rotation-contact with the cam lobe, wherein the surface roughness Ra of the outer circumferential surface of the roller is 0.4 to 2.2 μm.  
     
     
         4 . The valve train according to  claim 3 , wherein the surface roughness Ra of the outer circumferential surface of the cam lobe is 0.4 to 2.2 μm.