PROPORTIONAL ACTUATOR FOR PROPORTIONAL CONTROL DEVICES

A proportional actuator for proportional control includes a saturation tip formed on the movable armature the solenoid coil is a step-wound coil, providing clearance for the saturation tip, allowing the coaxial diameters the magnetic pole piece and of the armature to be increased for an actuator of a given size so that the amount of force which can be produced by this type of magnetic circuit is related to the coaxial diameters of the magnetic pole piece and the armature, the configuration of the armature provides significantly higher magnetic force attraction between the magnetic pole piece and the armature because of the increased coaxial diameters of the armature and the pole piece. In addition, because of the increased diameter of the armature, the surface area of the armature that is exposed to the saturation tip is increased, thereby increasing the amount of flux that is coupled to the magnetic pole piece by the saturation tip. The proportional actuator is described with reference to applications in proportional control valves. Highly preferred embodiments of the proportional control valve include a damping mechanism for minimizing overshoot by providing restricted fluid flow path between the region between the magnetic pole piece and the armature and tank pressure for fluid being supplied to or removed from the apparatus being controlled by the proportional control valve.