Valve lifter with integral hydraulic lash adjuster and a method of measuring its dry length

Abstract

A roller hydraulic valve lifter comprising a prior art lifter body assembly having a roller assembly at a first end for following a camshaft cam, an oil chamber connectable to an engine oil gallery, and a pushrod seat slidably disposed in an open second end and having a socket for engaging the end of a valve pushrod. A prior art hydraulic lash adjuster is disposed within the chamber. An adapter between the head of the lash adjuster and the pushrod seat transfers motion of the lash adjuster to the pushrod seat. An advantage of combining a lash adjuster with a lifter body assembly is that the lash adjuster has a passage in the head and the valve is inverted from the orientation of the original check valve. By inserting a pin through the pushrod socket, oil can be drained to permit measurement of dry length without requiring complete disassembly.

1 . A hydraulic valve lifter assembly for transmitting motion of a camshaft lobe to a pushrod in an internal combustion engine, comprising: 
 a) a hydraulic lifter body having a blind bore having an open end and a closed end;    b) a pushrod seat slidably disposed in said blind bore at said open end to define a chamber in said lifter body assembly;    c) a hydraulic lash adjuster disposed in said chamber and having    a lash adjuster body, and    a plunger slidably disposed in said lash adjuster body, said plunger having a head extending from said lash adjuster body, said plunger being hollow to define an oil reservoir therewithin, said plunger including a check valve in communication with said reservoir and disposed in a high-pressure chamber between said plunger and said lash adjuster body; and    d) an adapter disposed between said plunger head and said pushrod seat.    
   
   
       2 . A hydraulic valve lifter assembly in accordance with  claim 1  further comprising a slider disposed at said closed end of said lifter body for following a cam lobe.  
   
   
       3 . A hydraulic valve lifter assembly in accordance with  claim 2 , wherein said slider is selected from the group consisting of a slider foot and a roller.  
   
   
       4 . A hydraulic valve lifter assembly in accordance with  claim 1  wherein said chamber is defined by a space between said hydraulic lash adjuster and said blind bore of said body.  
   
   
       5 . A hydraulic valve lifter assembly in accordance with  claim 4  wherein said chamber is an oil reservoir communicable with an oil gallery of said engine.  
   
   
       6 . A hydraulic valve lifter assembly in accordance with  claim 4  wherein said plunger head includes an axial passage defining a communication between said chamber and said oil reservoir within said plunger.  
   
   
       7 . A hydraulic valve lifter assembly in accordance with  claim 1  wherein a linear axial opening exists through said pushrod seat, through said adapter means, and through said plunger to said check valve.  
   
   
       8 . A hydraulic valve lifter assembly in accordance with  claim 1  further comprising a metering disk disposed between said pushrod seat and said adapter.  
   
   
       9 . A hydraulic valve lifter assembly in accordance with  claim 1  wherein said pushrod seat and said adapter are formed as one piece.  
   
   
       10 . A method of measuring a net mechanical length of a hydraulic valve lifter assembly initially filled with oil, said assembly including a hydraulic lash adjuster disposed in a bore of a lifter body, and a pushrod seat assembly disposed proximate said lash adjuster, wherein said lash adjuster further includes a valve assembly having a seat and a valve selectively seatable against said seat, and a high pressure chamber defined by a space between said valve assembly and said body, said seat assembly, lash adjuster and seat of said valve assembly having axially aligned openings, the method of measuring a net mechanical length of a hydraulic valve lifter assembly initially filled with oil including: 
 a) inserting a pin through said opening in said seat assembly, said opening in said lash adjuster and said opening in said seat of said valve assembly;    b) moving said valve away from said valve seat to open said valve assembly;    c) releasing oil from said high pressure chamber; and    d) measuring the net mechanical length of the valve lifter assembly taken from a reference point on said body and a reference point on said pushrod seat assembly.    
   
   
       11 . A method of measuring a net mechanical length of a hydraulic valve lifter assembly in accordance with  claim 10 , wherein said pushrod seat assembly includes a pushrod seat, an adapter and a metering valve disposed between said seat and adapter, said method including the step of removing said metering valve from said hydraulic valve lifter assembly before inserting said pin.