Patent ID: 9202652
Filing Date: 2015-12-01
Classification: H01H

Abstract:
1. An electromagnetic contactor, comprising: a pair of fixed contacts disposed to maintain a predetermined interval and a movable contact disposed to be capable of connecting to and separating from the pair of fixed contacts; and an electromagnet unit that drives the movable contact, including: a plunger drive portion; a magnetic yoke enclosing the plunger drive portion; an upper magnetic yoke covering an upper portion of the magnetic yoke; a movable plunger having a leading end protruding through an aperture formed in the upper magnetic yoke, a peripheral flange portion formed on a side of the protruding end, and a lower portion, the movable plunger being urged by a return spring; an annular permanent magnet fixed onto the upper magnetic yoke to enclose the peripheral flange portion of the movable plunger, and magnetized in a moving direction of the movable plunger; and a cylindrical auxiliary yoke disposed to partly overlap the lower portion of the movable plunger so that a magnetic circuit passing through the upper magnetic yoke, magnetic yoke, auxiliary yoke and movable plunger is formed, wherein relationships among a gap g1 between a lower surface of the peripheral flange portion of the movable plunger and an upper surface of the upper magnetic yoke, a gap g2 between an outer peripheral surface of the movable plunger and the aperture of the upper magnetic yoke, a gap g3 between the outer peripheral surface of the movable plunger and the cylindrical auxiliary yoke, and a gap g4 between a lower surface of the movable plunger and an upper surface of a bottom plate portion of the magnetic yoke are set as g1<g2 and g3<g4 when the plunger drive portion is not energized.