Hydraulic valve lash adjuster for a valve train of an internal combustion engine

摘要

A hydraulic valve lash adjuster for a valve train of an internal combustion engine, for example for an automotive vehicle, said hydraulic valve lash adjuster comprising a piston (2) that is guided for displacement in a piston housing (4) and elastically supported against said housing, said piston (2) comprising a low pressure chamber (3) that communicates via an axial opening (26) in a piston bottom (19) with a high pressure chamber (5) defined by the piston housing (4) and the piston (2), and further comprising a control valve (6) acting between said pressure chambers (3, 5), said control valve (6) comprising a valve closing body (7) that can be brought to bear sealingly against a valve seat (24) that surrounds the axial opening (26) on a piston body undersurface (28) and is received in a closing body cap (9) whose cap bottom (21) acts as a stroke limitation of the valve closing body (7), and said control valve (6) further comprising a control valve spring (8) that loads the valve closing body (7) in opening direction, and, during a collapsing movement between the piston (2) and the piston housing (4), said valve closing body (7) being hydraulically loadable in closing direction against the biasing force of the control valve spring (8) by a pressure build-up in the high pressure chamber (5).;To improve the valve lash adjuster so that undesired operational fluctuations are reduced, the valve closing body (7) is configured as a needle-shaped, elongate sealing piston whose valve seat-proximate end comprises a plate-shaped sealing surface (10) that cooperates with a correspondingly configured sealing surface (25) of the valve seat (24) and whose valve seat-distal end comprises a surface of application (12) for hydraulic loading, and the valve closing body (7) substantially fills a space volume of the closing body cap (9) surrounding the valve closing body (7).