Electromagnetic actuator for an engine valve, including an integrated valve slack adjuster

摘要

An electromagnetic actuator includes a housing; two spaced electromagnets disposed in the housing and having respective pole faces oriented toward one another; an armature movable between the pole faces; an opening spring and a closing spring exerting oppositely directed forces to the armature; a supply arrangement for delivering hydraulic oil under pressure; and an armature stem affixed to the armature and having a free end oriented toward a free end of a valve stem of an engine valve of an internal-combustion engine. The valve stem and the armature stem are urged toward one another by the opening and closing springs. The armature stem is provided with a channel adapted to be supplied with hydraulic oil from the supply arrangement. Further, a guide is provided for supporting and guiding the armature stem in displacements thereof. A piston-and-cylinder unit, including a cylinder chamber, is disposed between the free and of the armature stem and the free end of the valve stem for transmitting displacement forces from the armature stem to the valve stem by the piston-and-cylinder unit. A valve assembly is provided which has a first state in which hydraulic communication is maintained between the supply arrangement and the cylinder chamber via the channel in the armature stem and a second state in which hydraulic communication is blocked between the supply arrangement and the cylinder chamber.