| 摘要 |
1,156,750. Transformers. SUPERIOR ELECTRIC CO. 2 June, 1967 [15 July, 1966], No. 25553/67. Addition to 1,022,780. Heading H1T. A winding e.g. for an auto-transformer, is provided with a commutating surface 22 which is contacted by a movable brush, the surface 22 being formed by a method comprising the steps of: (a) winding spaced turns of an insulated conductor 14 about a core e.g. a toroid, (b) depositing a coating of e.g. epoxy resin, on the surface of the coil which is to be contacted by the brush, (c) exerting pressure on the parts of the turns previously coated, while the coating is still semi-liquid, to force the coating material off these parts and into the adjacent interstices, (d) removing e.g. by grinding, the insulation and some of the conductor of these turns to form bared surfaces 26, and (e) depositing a good conductor e.g. gold, silver, rhodium, on the bared surfaces. The conductor 14 may be of copper and the core may be magnetic and comprise spirally wound strip metal. The epoxy coating may be applied by dipping the heated coil into epoxy powder which melts and coalesces on the coil, and the pressure may be applied by a resilient member e.g. of silicone rubber. During pressurizing the coil may be dipped in a cooling bath e.g. water, to solidify the epoxy material. The coating is forced into the interstices such that its level will be below that of the surface of the subsequently ground away conductor, and the inner and outer peripheral edges of the coil may be formed with thicker rims of the coating material (Figs. 8 and 9, not shown). The commutating surface may be formed on a raised part (21) (Fig. 1, not shown), of the surface of the coil. |
