Patent ID: 7464679

Claim:
A hydraulic lash adjuster ( 1 ) comprising a hollow cylindrical housing ( 2 ) that is inter-inserted with an axially relatively displaceable pressure piston ( 3 ), wherein a high pressure chamber ( 6 ) for hydraulic medium extends between opposing front ends ( 4 , 5 ) of the pressure piston ( 3 ) and the housing ( 2 ), which high pressure chamber ( 6 ) can be supplied, via a one-way valve ( 8 ) arranged on an undersurface ( 7 ) of the front end ( 4 ) of the pressure piston ( 3 ) and opening towards the high pressure chamber ( 6 ), with hydraulic medium out of a reservoir ( 9 ) enclosed by the pressure piston ( 3 ), a leak gap ( 12 ) for the hydraulic medium out of the high pressure chamber ( 6 ) is formed between an outer peripheral surface ( 10 ) of the pressure piston ( 3 ) and a bore ( 11 ) of the housing ( 2 ), the front end ( 5 ) of the housing ( 2 ) forms a stop surface ( 13 ) for an annular portion ( 14 ) of the front end ( 4 ) of the pressure piston ( 3 ) in a sunk state of the pressure piston ( 3 ), in a portion adjoining the front end ( 5 ) of the housing ( 2 ), the bore ( 11 ) of the housing ( 2 ) merges into an annular enlargement ( 15 ), wherein the front end ( 4 ) of the pressure piston ( 3 ) comprises in a transition region to the outer peripheral surface ( 10 ), a wiping chamfer ( 16 ) whose height (H F ) is larger than the height (H R ) of the annular enlargement ( 15 ) and the chamfer ( 16 ) has an angle (α) in a range of 30°±15° relative to the outer peripheral surface ( 10 ) of the pressure piston ( 3 ) and the lash adjuster to provide additional volume in this space where undesired particles can be dispersed without adhering to the pressure piston ( 1 ) is installed in a cam follower ( 17 ) or in a support element of a cam follower of a valve train of an internal combustion engine, or is an integral part thereof.