HOMOPOLAR ELECTRICAL MACHINES

1285026 Current collection in dynamoelectric machines INTERNATIONAL RESEARCH AND DEVELOPMENT CO Ltd 15 Aug 1969 [26 Aug 1968] 40643/68 Heading H2A In a dynamo-electric machine currentcollecting arrangement, a current-collecting surface disposed in a magnetic field set up by the machine is shaped and positioned such that it substantially follows the lines of force of the field, thus preventing circulating currents being induced in the current collector. Fig. 1 (not according to the invention) shows a homopolar machine having an annular superconducting stator coil 3. The rotor may comprise a drum, a single, continuous or radially-divided disc, or as shown, two conductive discs 5, 6 mounted on an insulating disc 1. Integral with or bolted to the inner and outer peripheries of the discs are rings 5a 5b, 6a, 6b forming the moving elements of current collectors and each is engaged by a number of parallel-connected brushes. Fig. 3 shows the portion X of Fig. 1 modified in accordance with the invention, the contact surface 7 of the ring 5a being frusto-conical so that it substantially follows the lines of force 4b. The surface 7 may alternatively be curved or comprise a number of frusto-conical portions.