Abstract:
Essentially instead of a shaft reciprocating within a tube at close tolerances it rides on the radius of ball bearings creating surface area reduction.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention relates to a valve guide for an internal combustion engine.  
           [0002]    A valve guide assembly includes a machined valve guide including an outer cylindrical surface and an inner bore having an exemplary diameter of 0.343 inch. The valve-guide is pressed into a suitable bore in the cylinder head of an internal combustion engine.  
           [0003]    A valve having a head and stem reciprocates within the bore, driven by a conventional cam machanism.  
           [0004]    Within the valve guide are a plurality of semi-cyclindrical channels, opening into the bore of the guide. Three or more of these channels may be bored within the guide.  
           [0005]    Retained in the semi-cylindrical channels are a plurality of ball bearings. An exemplary diameter of 0.0315 inch, which reciprocate in an exemplary bore diameter of 0.033 inch.  
           [0006]    The bore is located within the guide, such as to permit the ball bearings, to protrude into the bore, such as to permit the valve stem to ball the only surface bearing area. This greatly reduces surface area and thereby friction within the valve guide.  
           [0007]    The ball bearings are retained within their bore by means of an internal snap ring.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a side elevation view, partly in cross-section, of a valve guide embodying the invention; and  
         [0009]    [0009]FIG. 2 is a cross-section taken on line  2 - 2  of FIG. 1, with some elements omitted. 
     
    
     DETAILED DESCRIPTION  
       [0010]    With reference to the drawings, a valve guide assembly, generally designated  10 , includes a machined valve guide  12  including an outer cylindrical surface  14  and an inner bore  16 , having an exemplary diameter of 0.343 inch. The valve guide  12  is pressed into a suitable bore in the head of the internal combustion engine, as is well known.  
         [0011]    A valve  18  having a head  20  and a stem  22  reciprocates within the bore  16 , driven by conventional cam mechanism (not shown).  
         [0012]    Within the valve guide  12  are a plurality of semi-cylindrical channels  24 ,  26 , and  28 , opening into the bore  16 . In the illustrated embodiment there are three such semi-cylindrical channels  24 ,  26 , and  28 . However, a greater number, such as four, may be provided if desired.  
         [0013]    Retained in the semi-cylindrical channels  24 ,  26  and  28  are a plurality of ball bearings  30 . In the exemplary embodiement, the semi-cylindrical channels  24 ,  26 , and  28  have a diameter of 0.033 inch, and retain ball bearings having an exemplary diameter of 0.0315 inch. The semi-cylindrical channels  24 ,  26 , and  28  have openings, such as the representive opening  32 , configured such that ball bearings  30  project into the bore  16  approximately 0.001 inch, so as to contact the valve stem  22 , and prevent direct contact between the valve stem  22  and the bore  16 .  
         [0014]    The ball bearings  30  are retained within the semi-cylindrical channels  24 ,  26 , and  28  by representive plugs  34  and  36 , or by any suitable alternative, such as an internal snap ring cooperating with suitable machined structure on the valve guide  12 .  
         [0015]    At the bottom end of the guide there is an area of original bore  40 , to aid in the heat transfer and sealing purposes.  
       SUMMARY OF INVENTION  
       [0016]    Ball bearings incorporated within the wall of a valve guide reduces surface area, therefore reducing friction.