Hydraulic length compensator - has separator piston which allows leakage of pressure medium but no air into central LP area

摘要

An IC engine lift valve has a cup-shaped housing (6) which acts as a tappet for a cam (3) and a compensator piston (12) incorporating a support piston (14). A HP area (15) between the two cup-shaped pistons (12,14) contains a compression spring (16) to force the two pistons aparts. The HP area (15) takes pressure medium from a central LP area (18) via a non-return valve (24) in the support piston (14). The central LP area (18) is linked to a circular LP area (19) around the pistons and is bounded towards the top (10) of the housing (6) by a separator piston (17) which is moved in the support piston (14) by leakage and is held in place by a compression spring (121). USE - Prevents air passing from the circular to the central LP area; allows air to be drawn off the circular LP area.