GB295667A - Improvements in or relating to thermo-magnetically operated devices - Google Patents

Abstract

295,667. Automatic Telephone Manufacturing Co., Ltd., and Roseby, P. N. May 16, 1927. Motors operating by thermally-produced changes of permeability of magnetic circuit.-The movable member of a thermo-magnetic motor is composed of material which loses its magnetic properties on heating, located in the field of a magnet and adapted to be heated electrically in one part of the field whereby the heated portion becomes nonmagnetic and the member is moved by the attraction between the magnet and the unheated portion. In a form of motor for producing a continuous reciprocating motion, sources of heat are located on opposite sides of the magnet and are rendered effective alternately as the movable member reaches the limit of its travel in either direction or a restoring spring may replace one of the heating coils. The invention may be applied to an electric relay in which the member performs a limited movement in one direction. As shown applied to a motor for continuously rotating a flicker device simulating the effect of a coal fire, a saucer shaper rotary member A of glass having an irregular surface carries a circle of tape or wire E on a non-magnetic frame F. A suitable material for the tape is a nickeliron alloy containing 30-40 per cent of nickel and preferably comprising 63 per cent iron and 37 per cent nickel, the alloy being annealed at a temperature of 300‹ C. Pure nickel may be employed. A permanent magnet preferably of cobalt steel or an electromagnet D is fixed with one of its poles near the tape and in close proximity thereto is located an electric heater B. The heater is in series with a lamp G disposed beneath the plate A. The tape in the vicinity of the heater B is heated above its critical temperature and the unequal forces produced by the magnet cause rotation. As the tape moves away from the heater, it cools and regains its magnetic properties whereby a continuous rotation results. According to the Provisional Specification, a flicker device for use in imitation fires comprises a cardboard or other cylinder closed at one end by a piece of glass or aluminium sheet having irregular holes, a glass cylinder, or a pair of glass cylinders rotating in the same direction at different speeds. The magnetic ring may be such that it loses its magnetic properties at ordinary temperatures and a cooling effect for restoring them is provided by an external source.