Patent ID: 6047673
Filing Date: 2000-04-11
Classification: F01L

Abstract:
An electromagnetic actuator for operating an engine valve of an internal-combustion engine, comprising(a) two electromagnets defining a space therebetween;(b) an armature movably disposed in said space for reciprocation in response to electromagnetic forces generated by said electromagnets;(c) resetting springs operatively coupled to said armature for opposing armature motions effected by the electromagnetic forces;(d) a push rod affixed to said armature for moving therewith as a unit;(e) guide means for guiding said push rod; said guide means including(1) a guide cylinder; and(2) a push-rod piston carried by an end of said push rod; said push-rod piston being slidably received in said guide cylinder;(f) a setting piston slidably received in said guide cylinder and defining with said push-rod piston an intermediate chamber forming part of said guide cylinder; said setting piston having an end adapted to be operatively coupled to the engine valve;(g) fluid supply means for supplying hydraulic fluid into said intermediate chamber; and(h) fluid-control valve means having an open state in which said intermediate chamber communicates with said fluid supply means and a closed state in which hydraulic fluid is locked in said intermediate chamber for rigidly transmitting motions of said push-rod piston to said setting piston.