GB1330127A - Electromagnetic devices - Google Patents

Abstract

1330127 Dynamo-electric machines SMITHS INDUSTRIES Ltd 2 Oct 1970 [2 Oct 1969] 48579/69 Heading H2A In an electromagnetic device comprising a permanent magnet 41 rotatable into any of a plurality of positions according to the mode of energization of a winding arrangement associated with a multi-pole stator 20, the magnet may be subjected to starting torque, e.g. for rotation through 180 degrees, by energizing concurrently at least two windings, the commencement of energization of one of these two windings being delayed with respect to that of the other. The device shown is an indicator, the magnet being associated with an indicia carrying drum 42, Figs. 1, 3 (not shown). The stator 20 has ten poles and five windings 28-32 mounted on alternate poles, windings 29 and 32 being energized through delay circuits 55, 54 providing different delays. All of the windings are energized for every position of the magnet. The delay circuits may be connected in circuit permanently or may be switched in to circuit only when 180 degree magnet rotation is required. The delay circuits may be associated with two adjacent windings. In a modification, not shown, all of the windings except one are energized through delay circuits, the delays all being different. The drum 42 and a casing 24 carrying the stator are made of aluminium. In a further modification, Fig. 7 (not shown) the stator has fifteen poles, the windings 28-32 being mounted on every third pole.