Self-contained hydraulic lash adjuster

Claim 1

A self-contained hydraulic lash adjuster comprising a cylinder member having a closed end portion, a plunger slidingly mounted in said cylinder member, a reservoir chamber located in said plunger, a pressure chamber defined between said plunger and said closed end portion of said cylinder member, a check valve for allowing fluid flow only from said reservoir chamber to said pressure chamber through a passage in said plunger, a return spring stretched between said plunger and said closed end portion of said cylinder member for urging said plunger in the upward direction, a leakage clearance formed between an inner surface and an outer surface of said plunger, a first annular groove provided on said outer surface of said plunger, radial hole means extended through said plunger in communication with said first annular groove to connect said leakage clearance to said reservoir chamber, a second annular groove provided on said outer surface of said plunger above said first annular groove, a sealing member fitted in said second groove for providing fluid-tight seal between said plunger and said cylinder member, and having a pair of lips with sharp edged portions in contact with said outer surface of said cylinder member and being alternately deformed onto said outer surface of said cylinder member upon upward or downward movement of said plunger, a seat member for closing an open upper end portion of said plunger and for transmitting the thrust of a push rod to said plunger, and an elastomeric bag member having a generally tubular shape with a closed bottom end and an open upper portions, said open upper end being fixed to an upper end portion of said reservoir chamber, an interior of said bag member being normally disposed in communication with atmospheric pressure through hole means in said seat member and an outer surface of said bag member in fluid-tight contact with operating fluid in said reservoir chamber.