The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 11, 1998
Filed:
Oct. 15, 1996
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A movable core (71) is formed to have such an outer shape that the surface area of the movable core opposite to a yoke (51) is reduced in the region where the stop position, which is determined by balancing between the electromagnetic attracting force and a return spring (70), exceeds a certain position. Thus, when the movable core (71) is stopped in the certain position, the outer circumference surface of a larger-diameter portion of the movable core (71) faces the yoke and the magnetic flux passes through the magnetic passage as per designed. But when the movable core (71) is stopped beyond the certain position, both large- and small-diameter portions of the movable core (71) face the yoke (51) and the outer circumference area of the larger-diameter portion of the movable core (71) which faces the yoke (51) is reduced. Therefore, the magnetic flux becomes hard to pass through the magnetic passage and the electromagnetic attracting force is reduced. As a result, the movable core is less attracted to come close to or abut against the stationary core even when an overcurrent is applied to a coil, and deterioration in control performance possibly caused by residual magnetism is suppressed.