Valve actuation system having grooved adjusting screw

Abstract

A valve actuation system is disclosed for an internal combustion engine. The system may have a gas exchange valve, a rocker arm pivotally connected to a shaft, a pushrod, a lash adjuster disposed in the pushrod. The system may also have an adjusting screw disposed in the rocker arm and configured to engage and fluidly supply the lash adjuster. The adjusting screw may include a shaft having a threaded outer annular surface, and a head connected to the shaft and having a rounded outer surface and a flat end face. The adjusting screw may also include an axial passage passing through the flat end face, a radial passage formed in the shaft and extending from the threaded bore of the rocker arm to the axial passage, and at least one radial groove formed in the rounded outer surface of the head and passing through the axial passage.

What is claimed is: 
     
         1 . An adjusting screw for a valve actuation system, the adjusting screw comprising:
 an elongated cylindrical shaft having a first end, a second end, and a threaded outer annular surface extending between the first and second ends;   a head connected to the elongated cylindrical shaft at the first end and having a rounded outer surface;   an axial passage formed in the elongated cylindrical shaft and passing through the head; and   at least one radial groove formed in the rounded outer surface of the head and connected with the axial passage.   
     
     
         2 . The adjusting screw of  claim 1 , wherein the axial passage is a blind passage. 
     
     
         3 . The adjusting screw of  claim 2 , further including a radial passage formed in the elongated cylindrical shaft and extending from the axial passage through the rounded outer surface. 
     
     
         4 . The adjusting screw of  claim 3 , further including a restrictive orifice formed in the radial passage. 
     
     
         5 . The adjusting screw of  claim 3 , wherein the at least one radial groove is oriented generally orthogonal to an axis of the radial passage. 
     
     
         6 . The adjusting screw of  claim 1 , wherein the at least one radial groove passes through the axial passage. 
     
     
         7 . The adjusting screw of  claim 1 , wherein:
 the head includes a planar shoulder located opposite the rounded outer surface and oriented generally orthogonal to the axial passage; and   the at least one radial groove terminates short of the planar shoulder.   
     
     
         8 . The adjusting screw of  claim 1 , wherein the at least one radial groove has a consistent width and depth along its length. 
     
     
         9 . The adjusting screw of  claim 1 , further including a tool engagement head located at the second end. 
     
     
         10 . The adjusting screw of  claim 9 , wherein an outer diameter of the tool engagement head has an outer diameter that is the same as or less than an outer diameter of the elongated cylindrical shaft. 
     
     
         11 . The adjusting screw of  claim 1 , wherein a radius of the at least one radial groove is about 0.4-0.6 times a radius of the axial passage. 
     
     
         12 . The adjusting screw of  claim 11 , wherein the head includes a flat end face formed at a center of the rounded outer surface around the axial passage. 
     
     
         13 . The adjusting screw of  claim 12 , wherein the flat end face has an outer diameter of 45-55% of outer diameter of the rounded outer surface. 
     
     
         14 . An adjusting screw for a valve actuation system, the adjusting screw comprising:
 an elongated cylindrical shaft having a first end, a second end, and a threaded outer annular surface extending between the first and second ends;   a head connected to the elongated cylindrical shaft at the first end and having a rounded outer surface;   an axial passage formed in the elongated cylindrical shaft and passing through the head;   a flat end face formed at a center of the rounded outer surface around the axial passage; and   at least one radial groove formed in the rounded outer surface of the head.   
     
     
         15 . The adjusting screw of  claim 14 , wherein the at least one radial groove is also formed in the flat end face. 
     
     
         16 . The adjusting screw of  claim 14 , further including:
 a radial passage formed in the elongated cylindrical shaft and extending from the axial passage through the rounded outer surface; and   a restrictive orifice formed in the radial passage.   
     
     
         17 . The adjusting screw of  claim 14 , wherein:
 the head includes a planar shoulder located opposite the rounded outer surface and oriented generally orthogonal to the axial passage; and   the at least one radial groove terminates short of the planar shoulder.   
     
     
         18 . The adjusting screw of  claim 14 , wherein the at least one radial groove has a consistent width and depth along its length. 
     
     
         19 . The adjusting screw of  claim 14 , further including a tool engagement head located at the second end, wherein an outer diameter of the tool engagement head has an outer diameter that is the same as or less than an outer diameter of the elongated cylindrical shaft. 
     
     
         20 . A valve assembly, comprising:
 at least one gas exchange valve;   a shaft;   a rocker arm pivotally connected to the shaft and having a first end operatively engaged with the at least one gas exchange valve, a second end with a threaded bore, and a passage extending from the shaft to the threaded bore;   a pushrod having a cam end and a rocker arm end;   a lash adjuster disposed in the rocker arm end of the pushrod; and   an adjusting screw disposed in the second end of the rocker arm and configured to engage and fluidly supply the lash adjuster in the pushrod, the adjusting screw including:
 an elongated cylindrical shaft having a first end, a second end, and a threaded outer annular surface extending between the first and second ends; 
 a head connected to the elongated cylindrical shaft at the first end and having a rounded outer surface and a flat end face formed at a center of the rounded outer surface; 
 an axial passage formed in the elongated cylindrical shaft and passing through the flat end face of the head; 
 radial passage formed in the elongated cylindrical shaft and extending from the threaded bore of the rocker arm to the axial passage; and 
 at least one radial groove formed in the rounded outer surface of the head and passing through the axial passage.