Hydraulic lash adjuster equipped with auxiliary check valve

Abstract

An auxiliary check valve is provided in a hydraulic lash adjuster of the type wherein the plunger-to-body clearance is sealed. The auxiliary check valve is derived so that it remains open until the plunger has been moved to the limit of its travel by rotation of the engine camshaft during engine assembly. The auxiliary check valve permits fluid within the hydraulic lash adjuster high pressure chamber to be displaced to the reservoir chamber allowing the hydraulic lash adjuster to shorten from its free length to the proper installed length.

1 . A hydraulic lash adjuster assembly for an internal combustion engine, the lash adjuster comprising:
 a) a lash adjuster body having a body bore formed therein;   b) a plunger assembly that includes a reservoir chamber equipped to contain therein a supply of hydraulic fluid positioned within said body bore;   c) a fluid pressure chamber formed between the bottom of said bore and the bottom of said plunger assembly;   d) a valve opening in said plunger assembly to permit fluid communication between said reservoir chamber and said pressure chamber;   e) a plunger check valve for selectively opening and closing said check valve arranged such that the check valve opening remains open until closed by concurrent engagement of the check valve element and the plunger assembly with the bottom of the body bore in response to a linear movement of the plunger assembly thereby retaining the check valve opening in a closed position until opened by outside intervention;   f) a biasing means for urging the plunger assembly in a direction that increases the volume of the pressure chamber to take up slack of a valve drive train;   g) a sealing means engaging the plunger assembly in response to movement of the plunger for restricting fluid flow from the pressure chamber and to inhibit further movement of the plunger assembly; and   h) said lash adjuster being arranged such that the plunger assembly is disengaged from said sealing means and pressure in said pressure chamber is relieved upon movement of the plunger assembly as the volume of the pressure chamber increases so as to limit inward movement of the plunger assembly when a load is applied to the plunger assembly and before the pressure chamber is again closed.   
   
   
       2 . The lash adjuster of  claim 1  wherein the fluid chamber contains a supply of hydraulic fluid. 
   
   
       3 . The hydraulic lash adjuster of  claim 1  where said valve opening in said plunger assembly comprises a cylindrical coaxial portion and where said plunger check valve comprises a complementary cylindrical coaxial portion. 
   
   
       4 . The hydraulic lash adjuster of  claim 1  wherein said valve opening in said plunger assembly comprises a cylindrical coaxial tapered portion and where said check valve element comprises a spherical configuration coupled with a mating sealable complemental opening. 
   
   
       5 . The hydraulic lash adjuster of  claim 3  wherein the check valve element is provided with at least one groove providing fluid communication between said fluid chamber and said pressure chamber such that when said check valve is open, said groove communicates with fluid between said reservoir chamber and said pressure chamber. 
   
   
       6 . The hydraulic lash adjuster of  claim 3  where said groove is longitudinal. 
   
   
       7 . The hydraulic lash adjuster of  claim 3  where said groove is helical. 
   
   
       8 . In a hydraulic lash adjuster system for an internal combustion engine, comprising an outer cylindrical body, a plunger assembly slideably positioned within said body and a valve pin movably positioned within said plunger assembly, the improvement comprising:
 a) a moveable plunger equipped with an auxiliary check valve in combination with said lash adjuster;   b) said check valve devised to be maintained in an open position until the plunger has been moved to a level of its movement range;   c) said combination upon installation in association with an engine valve with valve spring and with rotatable camshaft enables the check valve to be maintained in a closed position by means of a locking contacting engagement by a self-locking auxiliary check valve.