US Patent 7328676 Hydraulic valve play compensation element

A hydraulic valve play compensation element for an internal combustion engine is provided as a reverse-spring/free-ball element, with a cylindrical housing, a cylindrical piston (21) guided therein with sealing play and a control valve (20), which is arranged between a low-pressure chamber (22) of the piston (21) and a high-pressure chamber (24) of the housing, on a piston head (25) of the piston and which has a closing body (27), which can contact a valve seat (26) surrounding an axial bore hole (23) of the piston head (25) when carrying out a stroke (28) in the closing direction against the force of a control-valve spring (34) and which can contact a contact surface (29) of a valve cap (30) surrounding the closing body (27) when carrying out a stroke in the opening direction. In a region of the axial bore hole (23) for the closing body (27) there is a narrow guidance surface (32) with gaps, which enable a volume flow of hydraulic medium between the high-pressure chamber (24) and the low-pressure chamber (22).