GB809441A - Improvements relating to polarised electromagnetic relays and like devices - Google Patents

Abstract

809,441. Electromagnetic relays. CARPENTER, R. E. H. July 6, 1955 [July 12,1954; Sept. 3, 1954], Nos. 20332/54 and 25685/54. Class 38 (5). A polar relay comprises a U-shaped core 3, 4 energized by coils 1, 2 and having extension plates 5, 6 forming pole faces between which a permanent magnet armature 15 with soft iron end-pieces 16 is rockable about a pivot 17. The end-pieces 16 reduce the reluctance of the controlling magnetic circuit and thus increase the control flux. Alternatively, the polarizing magnet may be stationary and the endpieces 16 connected together to form the armature. The plates 5, 6 are spaced apart by a pair of non-magnetic bars 7 fixed therebetween by bolts 8, 9, this assembly being closed at the bottom by a plate 12 and at the top by an insulating disc 11 so that the armature oscillates in a dust-tight housing. The armature pivot pins 17 have elastomer sleeves 18 mounted in metal bushes 19, as disclosed in Specification 809,442, the bushes being received in slightly larger openings 21 in the bars 7 and clamped in the desired adjusted position by a plate 24 and screws 24a. An arm 28 fixed to a pin 17 has a bent-over horizontal upper end carrying an insulating contact-operating bead 31. This bead is engaged on opposite sides by a pair of ears (Fig. 2, not shown), depending downwardly from the free end of a spring contact blade 33 fixed in a post 50 whereby oscillation of the armature causes contacts 34 on the blade to engage contacts 35 carried by a pair of fixed contact strips 36. The arm 28 comprises a magnetic strip having a boss 30 pivotally supporting a permanent magnet plate 29 held against the arm by its own flux, relative movement between the arm and plate producing a frictional armature-damping force as disclosed in Specification 673,867. The strips 36 are fixed at one end to rigid backing bars 37 and spaced a small distance therefrom their free ends rubbing on friction plugs 38 to reduce contact chatter as disclosed in Specification 484,472. The bars 37 are mounted by resilient strips 45 fixed to posts 46, screws 47 entering the posts and engaging the bars 37 permitting adjustment of the contacts 35. The post 50 carrying the blade 33 upstands from a triangular plate 51 pivoted about the conical under-surface of a screw 52 and clamped to the disc 11. by the screw 52 and a pair of screws 53, 54 passing through larger holes in the plate whereby the contacts 34 may be " centred ". In another construction (Figs. 7, 8, not shown), the cores 3, 4 are spaced further apart and the plates 5, 6 extend downwardly therebetween. Specification 734,352 also is referred to.