GB1160622A - Improvements in and relating to Electrical Instrument Movements - Google Patents

Abstract

1,160,622. Electric meters; indicating apparatus. HONEYWELL Inc. Feb. 24, 1967 [March 10, 1966; March 11, 1966; March 14, 1966], No. 9049/67. Headings G1J and G1Q. The coil 26 of a moving coil instrument moves in the space between a core 18 and a cylindrical yoke 10, the core and yoke being fitted together and spaced apart by bifurcated members 17 which have tongue and groove engagement with both the core and the yoke. Torsional suspension elements such as taut bands 31a, 31b are each secured at one end to the coil and at the other to one of the members 17. Movement assembly Fig. 1 The coil former 28 has inwardly projecting lugs 28e substantially on the axis of the movement and these are entered, by way of slots 24, into cavities 22 in the permanent magnet core 18. These cavities allow a clearance all round the lugs, but the clearance is sufficiently small to ensure that movement of the coil transversely of its axis is limited. The members 17 each have internal tongues, 14b, 16b which fit (either tightly, or loosely in which case they are secured by adhesive) in grooves 20 in the core. They also have external tongues 14c, 16c which are similarly fitted in grooves 10b in the ferrous yoke 10. Before such fitting, the inner ends of the taut bands 31a, 31b are secured as described below to members 32, 34 (the former of which incorporates a pointer 32a) and these members are clipped on to the coil former 28 by bending lugs 28a, 28c on the coil former over them; and after fitting the coil and core in the yoke, the outer ends of the taut bands are secured to resilient anchorages 36 which in turn are secured to the members 17, e.g. by grommets 40 which fit in holes 36a, 17a in the anchorages 36 and members 17 respectively. The movement, already located in yoke 10 by the engagement of tongues 14c, 16c on the members 17 in its grooves 10b, may be securely retained in the yoke by crimping the latter at its top end. The portions 14d, 16d of the lower member 17 engage the bottoms of the grooves 10b and the crimped-over top end of the yoke 10 similarly engages the corresponding portions of the upper member 17. Suspension details Fig. 3 The taut band 31a (and similarly the other taut band 31b) has its end portions 31c, 31d disposed at substantially 90 degrees to its freely suspended centre portion, and these end portions lie respectively on the member 32 secured to the coil and on the spring anchorage 36. Plates 32c, 36b are then laid over the respective ends of the taut band and spot welded to the members 32 or 36 on which they lie. The weld preferably secures the band itself to both the plate and the underlying member, at a point close to the bend in the band.