GB1299057A - Improvements in electrical machines - Google Patents

Abstract

1299057 Dynamo-electric machines KOLLMORGEN CORP 19 April 1971 [8 April 1970] 27061/71 Heading H2A A D.C. machine has a field with 2p poles where p is an integer greater than one, an armature with 2n coils where n is an integer greater than p and is not an integral multiple of p, and a commutator having 2n segments, diametrically opposite armature coils being connected in series between two commutator segments and diametrically opposite commutator segments being interconnected. Fig. 1 shows diagrammatically a four-pole machine with six armature coils 1-2...11-12 and six commutator segments a...f. Each coil spans about 2/3 of a pole pitch and pairs of coils, such as 1-2 and 7-8, spaced apart by a double pole pitch, are connected between spaced segments such as a and e. A pair of brushes B is provided spaced apart by a pole pitch and interconnections are made between the segments as shown. Other four-pole machines with ten coils and segments and fourteen coils and segments are illustrated, Figs. 2 and 3 (not shown). The machine may have a cylindrical air gap with preferably a permanent magnet field, Fig. 4 (not shown), or a planar air gap, Figs. 5 and 7. The rotor disc 40, which carries six coils 61 ... 66 connected to a commutator C on one face of the disc, may consist of ferrite material or an insulating material mixed with magnetic powder and is located between a ferrite ring 20 formed with permanent magnet poles, or a ring carrying salient poles, and a soft-iron plate 21 or a further magnetized ferrite ring. Diametrically opposed coils may be constructed as a single coil as shown in Fig. 8 for example at 70-71, the central portions of the coils being superimposed. In this case, a separate carrier disc is unnecessary, the coils being moulded in thermosetting resin together with the commutator. The coils may comprise printed circuit spirals on separate, thin discs which are laminated together to form the rotor.