Variable valve timing IC engine - has cam tappet operated by hydraulic fluid connected to sprung piston chamber during variable part of tappet stroke

摘要

The variable valve control is esp. for a valve of a reciprocating piston combustion engine. The valve (4) is opened against a spring (6) by a cam (8) which acts on a tappet (12) slidable in the bore (14) of a guide bush (16). The tappet movement is transmitted to a valve operating plunger (20) in that bore via hydraulic fluid in a chamber (22) between them. This chamber is connected to an external chamber (32) during part of the tappet stroke. This part is adjustable e.g. by rotating the bush (16). The chamber (32) is bounded by a spring-loaded (34) piston (36).