GB980686A - Impulse-type electromagnetically actuated devices - Google Patents

Abstract

980,686. Electromagnets. W. W. CLEMENTS. Feb. 14, 1961, No. 5501/61. Addition to 854,030. Heading H1P. [Also in Division H2] The armature of an electromagnet is moved between two stable states by means of an auxiliary member of magnetic material which, when the coil is energized, moves to a position which alters the configuration of the magnetic circuit such that the armature is attracted to its other stable state and, when the coil is deenergized the auxiliary member returns to a neutral position. The electromagnet comprises a coil 15, enclosed in a magnetic housing comprising sleeve 17 and end-plates 16A, 16B, which surround armature 6 of magnetic material which is attached to shaft 8 by pin 7. Attached to one end of the shaft is a bi-stable spring 12 held at its periphery in clamps 13. Loosely disposed on the shaft are members 19A, 19B of magnetic material joined together by a non-magnetic spacer (not shown) and located between plates 23A, 23B which are resiliently attached to the end-plates 16A, 16B and capable of displacement in slots 24 in brackets 9A, 9B. As shown, the armature 6 is in its bottom stable position and the auxiliary member is in its neutral position with plates 23A, 23B lying in the base of slots 24. If coil 15 is energized member 19B is attracted to the lower side of armature 6 thereby increasing the effective flux in the top air gap 18A so that the armature moves upward to its top stable position, Fig. 5 (not shown). Member 19B remains attached to the armature until the coil 15 is de-energized when the auxiliary member is returned to its neutral position under the action of spring 22A. Application of a further current pulse causes top member 19A to be attracted to the armature which is displaced to its lower stable position shown, the auxiliary member returning to its neutral position when the coil is de-energized. The end faces of the armature may be coated with non- magnetic material, e.g. brass, to ensure release of the auxiliary member. The embodiments of the bi-stable electromagnet shown in Specification 854,030 may be modified so that the auxiliary member returns to a neutral position when the coil is de-energized.