Patent ID: 6089197
Filing Date: 2000-07-18
Classification: F01L

Abstract:
An electromagnetic actuator combined with an engine valve of an internal-combustion engine for operating said engine valve; said engine valve including a valve stem having a free end; said electromagnetic actuator comprising(a) a housing;(b) two spaced electromagnets disposed in said housing and having respective pole faces oriented toward one another;(c) an armature movable between said pole faces;(d) an opening spring and a closing spring exerting oppositely directed forces to said armature;(e) supply means for delivering hydraulic oil under pressure;(f) an armature stem affixed to said armature and having a free end oriented toward the free end of said valve stem; said valve stem and said armature stem being urged toward one another by said opening and closing springs; said armature stem being provided with a channel adapted to be supplied with hydraulic oil from said supply means;(g) a guide for supporting said armature stem in displacements thereof;(h) a piston-and-cylinder unit disposed between said free and of said armature stem and said free end of said valve stem for transmitting displacement forces from said armature stem to said valve stem by said piston-and-cylinder unit; said piston-and-cylinder unit including a cylinder chamber; and(i) a valve assembly having a first state in which hydraulic communication is maintained between said supply means and said cylinder chamber through said channel and a second state in which hydraulic communication is blocked between said supply means and said cylinder chamber; in said second state hydraulic oil is being maintained captive in said cylinder chamber.