Patent ID: 6292077
Filing Date: 2001-09-18
Classification: H01F

Abstract:
An electromagnetic actuator comprising:an electromagnetic coil wound around a bobbin having a central hole,a magnetic frame made of a magnetic material arranged on a periphery of said coil,a movable iron core which is inserted through the central hole of said bobbin and is slidable in an axial direction of said central hole,a first sleeve which is cylindrically made of a magnetic material, magnetically coupled with said magnetic frame by being inserted into one end side of said central hole, and mutually engaged with said movable iron core over an entire stroke of said movable iron core, anda second sleeve which is cylindrically made of a magnetic material, magnetically coupled with said magnetic frame by being inserted into the other end side of said central hole, and spaced from said first sleeve in the axial direction of said central hole, said second sleeve having an end opposing said first sleeve in close proximity to said movable iron core but not in engagement therewith at a retreated stroke end of said movable iron core, said second sleeve being arranged to be gradually engaged with said movable iron core as said movable iron core advances.wherein said movable iron core extends outside of said magnetic frame when at the retreated stroke end.