A SOLENOID FOR EFFICIENT PULL-IN AND QUICK LANDING

摘要

A solenoid (800) with improved pull-in and landing characteristics. As a solenoid armature (840) closes toward contact with the pole faces of a yoke (830), a geometric redistribution of a constant total flux causes the force to increase with decreasing gap. Latching force at saturation is maximized when the latching contact area matches the tightest bottleneck in the flux path. The addition of ferromagnetic area not making latching contact preserves the maximum latching force, increases power efficiency for pulling at a distance, and increases the flux redistribution effect of increasing force with decreasing gap at constant flux. The extra constant flux force change at small gaps may be abrupt, for a high deceleration followed by a quick passive force increase to latch with low impact, or gradual, for tight servo control and very low impact. Conductive material can provide selective inductive damping near latching. Armature mass can be kept low despite the extra ferromagnetic area.