GB564665A - Improvements in electro-magnetic slip couplings, brakes and dynamometers - Google Patents

Abstract

564,665. Eddy current apparatus. ENGLISH ELECTRIC CO., Ltd., CARNEGIE, B. S., and AYRES, W. E. M. Dec. 18, 1942, Nos. 21115/43 (divided out of 564,635), 11059/43 and 20923/43. [Class 35] [Also in Groups XIX and XXXIV] An eddy current coupling, brake, or dynamometer comprises two relatively rotatable elements, one of which is a field system of the central coil heteropolar type, whilst the other is a secondary system of the kind consisting of an unlaminated magnetic core, the surface of which is provided with a pair of spaced rings of greater circumferential conductivity than the part between them. The core may be of a type described in Specifications 234,191, 266,780, [both in Class 35], and 551,414, having its surface provided with a number of teeth extending in the form of the conductor bars of the squirrel cage winding between end rings formed integrally with the teeth and with the rest of the core. Alternatively, each end of the secondary system may have a ring of material of greater electrical conductivity than the rest of the core, either additional or in place of the integral rings. The secondary system may surround, or be surrounded by the field system. As shown in Fig. 1, the field system, mounted on a shaft 10, comprises a central coil 1 surrounded by magnetic rings 5, 6 provided with imbricated poles 5a, 6a, which co-operate with a secondary system comprising rings 18a connected by a reduced portion having spaced teeth 18b projecting towards the poles. When the device is used as a brake, the secondary member is stationary and may be provided with fins 18c projecting into an annular channel through which cooling fluid is passed. In the construction shown in Fig. 4, the field system is of the form described in Specification 564,635 and comprises oppositely acting coils 1,2, sandwiched between magnetic discs 5-7 which terminate in imbricated poles 5a, 6a, 7a, the latter cooperating with the secondary member consisting of rings 18a connected by a reduced portion having teeth 18b, the secondary system being supported from the driving shaft 11 by a disc 17. The field system is carried by a disc 14 welded to the disc 7 and to a hub 16 which is bolted to the driving shaft 10. The pole faces of the field system may be slotted along their length to form thereon two or more teeth whereby the frequency current induced in the secondary system is increased.