Patent GB-569921-A (GB)
Title: Electro deposition of rubber-like substances on the windings of electrical devices
IPC: C25D13/12
Filed: 1943-06-18
Abstract: 569,921. Insulation for dynamoelectric machines. SIGMUND, F., and HLAVIN, W. S. June 18, 1943, No. 9872. [A Specification was laid open to inspection under Sect. 91 of the Acts, Sept. 27, 1943.] [Class 35] [Also in Groups V, VIII and XXXVI] The windings of a submersible motor are rendered fluid-tight by immersing the wound core in an aqueous dispersion of a rubber-like substance which is deposited on the coil windings by electro-deposition, using the coil windings as one pole of the electric circuit. The aqueous dispersion includes the natural latex of, for example, rubber, gutta-percha or balata, or a synthetic latex of, for example, the polymers of butadiene or other diolefins, or artificial dispersions prepared from such substances or from waste or reclaimed rubber. The dispersions may be combined with filters, dyes, vulcanizers, accelerators, &c. The expression rubber-like substance also includes resins such as shellac, polymers of vinyl chloride, vinyl acetate and copolymers thereof, which may be deposited by electro-deposition. In carrying out the process, the wound core 20, Fig. 3, is immersed in a bath 26 of the dispersion in a container 25 which has a central post 29 and brackets 28 which enter and support the core. The terminal wires 22 of the winding are connected to one pole of a source of current and the core and container to the other. Circulation of the dispersion is obtained by a pump 32 and conduits 33, 34. The space above the dispersion is connected to an exhaust pump 37 and a valve 39 so that vacuum and pressure may be applied. alternately for degassing and consolidating the deposited material. Preferably, the coil wire 44, Fig. 5, is coated as at 45, with zinc, lead, cadmium, tin, antimony and has a porous covering 46 of cotton &c. Spacers may be provided to keep the coils clear of the slots and where a wedge 48, Fig. 8 (not shown), is used, this is grooved and slotted to allow the circulation of the dispersion. In a modification, the slots are lined with rubber &c. sheet 50, Fig. 9. A metal wedge 54 is used and sealed by a deposited plug 55. In this arrangement, the coil ends are enclosed by rubber &c. deposited from the dispersion, and the ends of the sleeve are prepared by a suitable rubber cement to give a good bond between the deposited rubber and the sleeve. To promote the circulation, and also to provide passages for cooling-fluid in the finished core, the coil slot 23 may be provided with a longitudinal opening 26, Fig. 12, communicating with the bottom of the slot. Alternative devices for circulating the dispersion comprise helical screw conveyers passing through the core apertures, Fig. 17 (not shown,) or slotted tubes passing into the core apertures, Fig. 14 (not shown), and connected to the circulating pump 32. The deposited rubber &c. coating is dried by electro-endosmosis followed or not by air drying, and vulcanization which may be effected by heating current passed through the coil wire. Fig. 19 shows a tube 62 inserted into the coils and provided with apertures 63 which is used to remove the moisture and admit hot air to effect the drying and vulcanizing of the deposit. The apertures are closed by wax &c. during the depositing operation and subsequently removed by admitting heated air.