GB840099A - Variable coupling transformer devices - Google Patents

Abstract

840,099. Transformers; selsyn machines. SPERRY RAND CORPORATION. March 25, 1958 [May 13, 1957], No. 9568/58. Classes 35 and 38 (2). A variable-coupling transformer comprises two relatively displaceable members with parallel adjacent plane surfaces having windings so distributed as to produce a concentrated flux pattern printed on their adjacent opposed faces, a small air gap between them, and means for providing a portion of the magnetic flux path with a low reluctance. The displaceable members may be discs 18 and 27 of aluminium, with a very thin dielectric layer 22 and 26 on opposing faces, the windings 23 and 25 being printed thereon e.g. by the photo-etch process. Annular cores 20 and 29 of magnetic material, e.g. a ferrite, reduce the reluctance of the working flux path. Stator current is supplied through leads 60 and 61 and rotor current is brought out through leads 47 and 48 to slip rings 49 and 50. The windings form spirals 40 and 41, the radial elements thereof being spaced to provide a sinusoidal flux pattern of one complete cycle. Further very thin insulating layers having similar windings printed thereon may be superimposed over the first layer of windings and angularly displaced therefrom to provide more than one output so that the device may function as a " resolver " (Fig. 8, not shown). Instead of having magnetic cores the discs themselves may be magnetic; the windings being printed directly thereon (Fig. 7, not shown). An alternative arrangement in which the relative displacement of the members is linear, the windings forming square spirals, is described (Figs. 9 and 10, not shown).