Patent GB-700458-A (GB)
Title: Improvements relating to the production of electric windings
IPC: H01F17/00
Filed: 1948-10-05
Abstract: 700,458. Electric coils inductances and transformers. STRONG, H. V., and EISLER, P. Nov. 7, 1949 [Oct. 5, 1948 ; May 11, 1949], Nos. 28494/49 and 12611/49. Divided out of 700,452, [Group XXXVI]. Classes 35 and 38 (2) An electric winding of any desired length comprises a succession of plane layers each consisting of a flat material containing at least two flat spiral windings, as many of these layers being secured together as required and the windings connected in one or more sets in series or parallel. In one form, the insulating support 1 for the conductors consists of impregnated paper or fabric of inorganic fibres e.g. asbestos or glass, and the conductors are arranged in the form shown, in two series of repeating patterns consisting of pairs of spirals 3, 4 of generally S shape on opposite sides of the mid-axis X-X. The conductive turns may be of flat section material e.g. flattened wire, but are preferably stamped from copper foil. When the strip is doubled along the X-X axis, the end connections 5, 6 at the inner ends of the spirals are opposite each other and can be joined as by soldering or riveting. In the form shown in Fig. 1 the current in the superimposed coils 3, 4 flows in the same direction e.g. for use in a transformer or inductance, but in other forms (not shown) the currents flow in opposite directions to produce a non-magnetic circuit. The folded strip is now doubled in zig-zag fashion in alternate directions about axes 7 so as to add up the effects of all the coils, the desired number of coils being obtained by cutting off along one of the folds 7. Terminals 10 are provided for connection of the severed ends and small adjustments of the effective number of turns is made by connecting at points 9 separated by half a turn from the extreme end of the conductor. Holes 11 pierced through the layers allow the passage of magnetic cores &c. If the conductors are attached to one side of the insulating support, further insulation is incorporated to prevent contact during folding. Modifications are described in which a pair of strips are placed together instead of folding a single strip. Specifications 639,179, 639,658, [both in Group XI]; 639,111 and 639,178 are referred to in which methods of forming the spirals are described. Various ways are described of fitting magnetic cores to the coils to produce transformers or chokes. It is described how a heating strip may be formed by plaiting together a pair of strips at right angles to each other and folded over each other in turn, these strips being preferably non-inductively wound. In an alternative method of making the coil-bearing layers, Fig. 12, a strip 40 containing several conductors running along its length, is wound into coils 42 on formers of any desired shape and may be suitably bonded. This strip may be produced by weaving a tape in which the warp contains some conducting metallic ribbons separated by pairs of fibre threads or by interleaving strips of impregnated paper or fabric with the conducting strips as described in Specification 700,459. Specification 644,565 also is referred to.