GB913105A - An electrical device for sensing the angular position of a rotary member - Google Patents

Abstract

913,105. Transformers; selsyn machines. BODENSECWERK PERKIN-ELMER & CO. G.m.b.H. Aug. 17, 1959 [Sept. 24, 1958], No. 27996/59. Classes 35 and 38 (2). A transformer, whose output depends upon the angular position or speed of rotation of a body, comprises a number of primary and secondary windings disposed in a circle and connected so as to eliminate errors due to eccentricity of its parts. As shown in Fig. 1, the windings are mounted on polepieces on a stationary ring, the primaries on poles 1 . . . 4, the secondaries on flanking poles 1a . . . 4a and 1b . . . 4b. A rotor 6 has four ferromagnetic segments A 1 . . . A 4 which divert the flux from each primary pole differentially to the flanking poles. Thus, the difference in output between secondaries in each pair is a measure of the angular position of the rotor. Eccentricity errors are avoided by connecting corresponding windings in series. In an alternative arrangement (Figs. 3 and 4, not shown), there are six primary windings connected in alternate sense round the ring, and there are a like number of secondary windings disposed between them. Each secondary pole then receives flux from the primaries on either side of it, to an extent dependent on the position of the rotor. In the arrangement shown in Fig. 5, the stationary poles 10 carry the primary windings only, again in alternate sense, secondary coils 14 being mounted for rotation between the primary poles and a stationary ferromagnetic ring 12. The output is then at the supply frequency, but modulated in amplitude at a frequency dependent on the speed of rotation of the ring of secondary windings.