Hydraulic lash adjuster having a simplified plunger

Abstract

An improved hydraulic lash adjuster including a cup-shaped adjuster body, and a plunger assembly disposed within the adjuster body. The plunger assembly includes a stepped axial bore extending from a body inner end to a central oil passage opening onto a hemispherical pivot head. A valve seat for a check valve is disposed against the step, defining a low-pressure oil chamber in the axial bore. A check ball and lash adjustment spring are disposed against the seat in a high-pressure chamber formed between the valve seat and adjuster body. The body of the plunger assembly may be formed by inexpensive processes to a length equivalent to that of a prior art one-piece plunger to resist torsional side loads which may be imposed on the HLA in use. The separately formed valve seat may also be used in other hydraulic lash adjusters such as incorporated in hydraulic valve lifters.

1 . A plunger assembly for use in a hydraulic lash adjuster for eliminating lash in a valve train of an internal combustion engine, comprising: 
 a) a plunger for sliding within a lash adjuster body, said plunger including an inner end and an outer end for engaging a rocker arm of said valve train, wherein an axial bore extends from said inner end to communicate with said outer end, defining a low-pressure oil chamber; and    b) a separate seat element disposed in said axial bore at said inner end thereof, wherein said seat element includes a first beveled annular seat for mating with a check ball, a first end face in cooperation with a plunger spring, a second beveled annular seat formed in said element opposite said first beveled annular seat, and a second end face formed in said element opposite said first end face such that said element may be installed into said axial bore with either one of said seats being positioned to cooperate with said check ball and either one of said end faces being positioned to cooperate with said plunger spring.    
   
   
       2 . A plunger assembly in accordance with  claim 1  further comprising a port extending through a wall of said plunger for providing oil to said low-pressure oil reservoir.  
   
   
       3 . (canceled)  
   
   
       4 . (canceled)  
   
   
       5 . A plunger assembly in accordance with  claim 1  wherein said seat element is welded to said plunger.  
   
   
       6 . A plunger assembly in accordance with  claim 1  wherein said axial bore is formed by a process selected from the group consisting of boring, turning, screw-machining, powdered metal forming, and metal injection molding.  
   
   
       7 . A hydraulic lash adjuster for eliminating lash in a valve train of an internal combustion engine, comprising: 
 a) a lash adjuster body;    b) a plunger assembly slidably disposed in said adjuster body, said plunger assembly including a plunger having an inner end and an outer end for engaging said valve train,    wherein an axial bore extends from said inner end of said plunger to communicate with said outer end, said axial bore defining a low-pressure oil chamber in said plunger,    wherein a separate seat element is disposed in said axial bore said seat element having a first beveled annular seat for mating with a check ball, a first end face in cooperation with a plunger spring, a second beveled annular seat formed in said element opposite said first beveled annular seat, and a second end face formed in said element opposite said first end face, and    wherein a high-pressure chamber is formed between said seat element and said lash adjuster body;    c) a check valve for mating with said seat element to regulate flow of oil from said low-pressure oil chamber across said seat element into said high-pressure chamber; and    d) a lash adjustment spring disposed between said lash adjuster body and said plungers    wherein said element may be installed into said axial bore with either one of said seats being positioned to cooperate with said check ball and either one of said end faces being positioned to cooperate with said plunger spring whereby a substantially identical distance between said lash adjuster body and plunger is maintained.    
   
   
       8 . An internal combustion engine including a valve train, the engine comprising a hydraulic lash adjuster for eliminating lash in said valve train, said hydraulic lash adjuster including 
 a lash adjuster body,    a plunger assembly slidably disposed in said adjuster body, said plunger assembly including a plunger having an inner end and an outer end for engaging said valve train,    wherein an axial bore extends from said inner end of said plunger to communicate with said outer end, said axial bore defining a low-pressure oil chamber in said plunger, wherein a separate seat element is disposed in said axial bore, said seat element having a first beveled annular seat for mating with a check ball, a first end face in cooperation with a plunger spring, a second beveled annular seat formed in said element opposite said first beveled annular seat, and a second end face formed in said element opposite said first end face, and wherein a high-pressure chamber is formed between said seat element and said lash adjuster body,    a check valve for mating with said seat element to regulate flow of oil from said low-pressure oil chamber across said seat element into said high-pressure chamber, and    a lash adjustment spring disposed between said lash adjuster body and said plunger,    wherein said element may be installed into said axial bore with either one of said seats being positioned to cooperate with said check ball and either one of said end faces being positioned to cooperate with said plunger spring whereby a substantially identical distance between said last adjuster body and plunger is maintained.    
   
   
       9 . (canceled)