Patent ID: 6198369
Filing Date: 2001-03-06
Classification: F02M,F16K,G05D

Abstract:
A proportional actuator for a proportional control device, the proportional actuator comprising:a magnetic pole piece having a pole end surface of a first working diameter;an armature adapted for movement relative to the magnetic pole piece between first and second positions, the armature having an armature end surface of a second working diameter which is substantially the same as said first working diameter and which is located adjacent to the pole end surface, the armature end surface being spaced apart from the pole end surface, providing a gap between said end surfaces when the armature is in the first position;a saturation tip which projects from one of said magnetic pole piece and said armature adjacent said end surface thereof towards the other one of said magnetic pole piece and said armature, the saturation tip being configured and arranged to bridge at least a portion of the gap when the armature is in the first position; anda coil assembly including a step-wound coil for moving the armature relative to the magnetic pole piece, the step-wound coil including a first coil portion having a first inner diameter, and a second coil portion having a second inner diameter which is larger than the first inner diameter, the first inner diameter being approximately the same as said first and second working diameters, and said second inner diameter being larger than an outer diameter of said one of said magnetic pole piece and said armature, including said end surface and the saturation tip thereof, defining for said coil assembly a region of increased diameter for receiving at least the saturation tip, allowing the saturation tip to be moved into overlapping relation with said other one of said magnetic pole piece and said armature when said armature is moved away from said first position.