GB462505A - Improvements in or relating to electric switches - Google Patents

Abstract

462,505. Electromagnetic switches. IGRANIC ELECTRIC CO., Ltd. May 25,1936, No. 14710. Convention date, June 13, 1935. [Class 38 (v)] [Also in Group XXXV] In an electric switch having a movable switch element biassed in the opening direction, a stop member is adapted to be engaged by said switch element upon movement under such bias to a given limit, said stop member being movable to permit overtravel of the element beyond said limit and being biassed in such a way that it returns said element to said limit, the stop member being associated with means for retarding its movement in both directions to arrest the switch element in said limit without rebound. As shown in Fig. 2, in an electromagnetic contactor the operating armature 8 is mounted in a pivoted carrier which is connected to the moving contacts by a bar 9. The lower end of the carrier projects downwardly so that when the armature falls back after operation the rounded lower end 21 engages the head 20 of a dashpot piston rod 13. This rod, as shown in Fig. 3, extends through the supporting plate 4 and carries a piston 12 working in the dashpot cylinder 11, a spring 18 bearing on the rear piston face. Thus, on release of the armature it moves rapidly to a limit position, after which overtravel beyond such limit is retarded by air being forced from the rear of the piston to the front through the clearance between the piston and cylinder and also through openings 19 in the piston. The armature is subsequently restored to the limit position by reason of the compression of the spring 18 which occurs during the overtravel movement, this restoring action also being similarly retarded. Thus a frictional dissipation of the kinetic energy of the armature is effected without rebound, the armature being restored to a position in which it will respond to an energizing current of the operating electromagnet 7 of relatively low value. The dashpot is preferably, as shown; of large diameter relative to its length.