Patent ID: 8502627
Filing Date: 2013-08-06
Classification: H01F,H01H

Abstract:
1. A relay comprising a yoke of a ferromagnetic material; a coil mounted on said yoke; a ferromagnetic core affixed onto said yoke and protruding through an axis of said coil; an armature formed of a ferromagnetic material having an armature bearing hinged onto said yoke, and said armature extending in a proximal-distal direction across the axis of the core, the armature being adapted to be pulled in to a closed position against said core when the coil is energized, a return spring mounted on said yoke and said armature and biased to pull the armature to an open position when the coil is de-energized; a movable contact mechanically affixed to said armature to move between open and closed positions; at least one fixed contact positioned to close electrically with said movable contact when the latter is in one of said open and closed positions; and the improvement wherein said core includes a core pole face at an axial end thereof in the form of a series of stepped flat strips that extend generally in respective generally horizontal planes that are substantially perpendicular to the axis of said core, and successive ones of which are joined by riser surfaces that extend from one said radial plane to the next thereof; and wherein said armature includes an armature pole face that is in the form of a corresponding series of stepped flat strips and riser surfaces the stepped flat strips and riser surfaces defining a succession of corner edges on the core pole face and armature pole face, respectively, and wherein said armature bearing is operative to cause said armature to travel in the proximal-distal direction as the armature moves from its open to its closed position to create a wipe motion, such that in the open position a first edge formed by a first riser surface and a first flat strip of the core pole face and first edge formed by a first riser surface and a first flat strip of the armature pole face are proximate to one another to form a first narrow gap therebetween to concentrate magnetic flux between the armature and the core at the first narrow gap, and as the armature moves from its open position towards its closed position, the transverse wipe motion of the armature causes the first edges to move away from one another and causes a second edge formed by a second riser surface and second flat strip of the core pole face and a second edge formed by a second riser surface and a second flat strip of the armature pole face to approach one another to create a second narrow gap to concentrate the magnetic flux lines between the armature and the core at the second narrow gap, and said wipe motion of the armature creates a vertical gap between the first vertical surface of the core pole face and the first vertical surface of the armature pole face, so that as the armature moves towards its closed position, a significant part of said flux flows across the vertical gap and reduces net acceleration of the armature; to provide thereby an increased initial closing force on the armature when the armature is at its open position and to limit the closing force as the armature moves to its closed position.