Recirculation groove for hydraulic lash adjuster

Claim 1

An engine valve train component which is operable in either a horizontal or vertical attitude, comprising: a body having a closed end, a chamber and an open end; a hollow plunger positioned within said chamber and having a portion extending outwardly through said body open end, a high pressure fluid chamber being formed between said body closed end and said plunger, said plunger having a closed interior end, a passage through said closed interior end, and a valve member controlling the passage of fluid through said closed interior end passage; a relief valve in the exterior end of said plunger in communication with the hollow interior thereof; a spring positioned in said high pressure fluid chamber; fluid passage means in said body in communication with the exterior of said plunger; a first unrestricted fluid passage in said plunger connecting the interior of said plunger with said body fluid passage means; and a second unrestricted fluid passage in said plunger connecting the interior thereof with the exterior, said second fluid passage including a circumferential groove on the exterior of said plunger and an opening extending between said groove and said plunger interior, said second fluid passage being closer to said high pressure chamber than said body fluid passage means and being located directly adjacent to said plunger closed interior end; with the portion of the plunger exterior located between the second fluid passage and the body fluid passage means being sized so as to fit closely against the body in substantially a fluid sealing relation wherein entrained air can flow between the plunger and body to escape out the open end of the body while fluid is prevented from passing between the plunger and body.