Internal combustion engine lifting valve electromagnetic actuator has facing armature, electromagnet surfaces shaped so normal magnetic field lines are shorter than surface separation

摘要

The actuator has an armature (4) moved in oscillation between two electromagnets (1,2) against the force of a restoring spring. The magnetic force-spring force characteristic applying over the armature's stroke is such that the magnetic force of the current carrying electromagnet is never less than the restoring spring force opposing armature capture. The facing armature and electromagnet surfaces (41,42,14,24) are shaped, at least in some areas, so that the lengths of the magnetic field lines (6,7) emanating normally from them is at least slightly shorter than the distance measured between the surfaces in the armature's direction of motion to achieve the desired characteristic.