Hydraulic lash adjuster

Abstract

A hydraulic lash adjuster ( 1 ) for a valve train ( 16 ) of an internal combustion engine, said hydraulic lash adjuster ( 1 ) comprising a hollow cylindrical housing ( 2 ) and a pressure piston ( 3 ) that are axially inter-inserted for axial displacement relative to each other, a bottom ( 4 ) of the pressure piston ( 3 ) comprising a central passage ( 5 ) for hydraulic medium from a reservoir ( 6 ) enclosed by the pressure piston ( 3 ) into a high pressure chamber ( 8 ) situated between the bottom ( 4 ) of the pressure piston ( 3 ) and an opposing bottom ( 7 ) of the housing ( 2 ), said passage ( 5 ) comprising, on an end ( 9 ) oriented toward the high pressure chamber ( 8 ), a one-way valve ( 10 ) that opens toward the high pressure chamber ( 8 ), wherein a flexible disk-shaped body ( 11 ), that is capable of floating on the hydraulic medium, extends within the reservoir ( 6 ). In this way, a “break-through” of air from the reservoir ( 6 ) into the high pressure chamber ( 8 ) is avoided. During a re-suction process in the lash adjuster ( 1 ), the body ( 11 ), so to speak, follows an air funnel that is being formed in the reservoir ( 6 ) in the direction of the one-way valve ( 10 ).

1 . A hydraulic lash adjuster, typically for a valve train of an internal combustion engine, said hydraulic lash adjuster comprising a hollow cylindrical housing and a pressure piston that are axially inter-inserted for axial displacement relative to each other, a bottom of the pressure piston comprising a central passage for hydraulic medium from a reservoir enclosed by the pressure piston into a high pressure chamber situated between the bottom of the pressure piston and an opposing bottom of the housing, said passage comprising, on an end oriented toward the high pressure chamber, wherein a flexible disk-shaped body, that is capable of floating on the hydraulic medium, extends within the reservoir.  
   
   
       2 . A lash adjuster of  claim 1 , wherein if a hydraulic medium column in the reservoir sinks to a level of a bottom of the reservoir, the body forms a disk valve-type seal of the passage at an end of the passage oriented toward the reservoir.  
   
   
       3 . A lash adjuster of  claim 1 , wherein the body is pre-shaped, so that when installed, the body has an at least slightly convex or funnel-shaped geometry in direction of the passage.  
   
   
       4 . A lash adjuster of  claim 1 , wherein the body is made of plastic.  
   
   
       5 . A lash adjuster of  claim 1 , wherein an edge of the body extends one of near a wall or on a wall of the reservoir.  
   
   
       6 . A lash adjuster of  claim 1 , wherein the body comprises circumferentially spaced recesses that start from an edge of the body.  
   
   
       7 . A lash adjuster of  claim 5 , wherein the body comprises circumferentially spaced recesses that start from the edge of the body.  
   
   
       8 . A lash adjuster of  claim 1 , wherein the lash adjuster is one of installable or installed in one of a switchable or a non-switchable roller tappet.