US463671A - Armature-core for dynamo-electric machines - Google Patents

Description

(No Model.)

E. THOMSON. ARMATURE CORE FCR DYNAMC ELECTRIC MACHINES.

No. 463,671. Patented Nov. 24, 1891.

UNITED STATES PATENT OFFICE.

ELIHU THOMSON, OF LYNN, MASSACHUSETTS, ASSIGNOR TO TIIE THOMSON- HOUSTON ELECTRIC COMPANY, OF CONNECTICUT.

ARMATURE-CORE FOR DYNAMO-ELECTRIC MACHINES.

SPECIFICATION forming part of Letters Patent No. 463,671, dated November 24, 1891.

Application filed August 5, 1889. Serial No. 319,829. (No model.)

To all whom t may concern.:

Be it known lthat I, ELIHU THOMSON, a citizen of the United States, and a resident of Lynn, in the county of Essex and State of Massachusetts, have invented a certain new and useful Improved Armature-Core for Dynamo-Electric Machines, of which the following is a specification.

My invention relates to the construction of cores for electric-induction apparatus subject to rapidly-varyin g magnetic polarization, and is designed more particularly for the cores of dynamo-electric generators and motors.

The invention consists, essentially, of a core built up from plates of thin sheet-iron or groups of sheet-iron plates consisting of the ordinary sheet-iron of commerce having the thin insulating scale or coating produced in the operation of manufacture, said sheets being separated from one another by the said plates of tin, zinc, or other non -magnetic metal. In this structure the thin coating or scale upon the sheet-iron disks or plates forms an electrical insulation, while the plates or washers of tin, zinc', or other non-magnetic metal form a magnetic insulation.

In the accompanying drawings, Figure l shows in plan the ordinary construction of a disk armature, the central portion being A are made from sheet-iron of small gage.

broken away. Fig. 2 shows in section a portion of an armature-core constructed in accordance with my invention. Figs?) and a are respectively a side elevation and edge view of a modified construction. Fig. 5 shows in edge view a further modication. Figs. 6 and 7 show in side elevation and section another modification.

In Fig. 2, D are disks or plates ot' thin sheetiron built u p laterally. This sheet-iron is the ordinary sheet-iron of commerce, which, as is well known, during the process of manufacture acquires a thin scale or coating, which is to some extent an electrical insulation. The plates are shown magnified in the drawings as to their thickness. In practice they tween groups of these pieces ot' sheet-iron are placed sheets of zinc Z, the whole being firmly held together by bolts B, surrounded by insulation I. It is not necessary that the sheets of zinc should fill' the entire space between the iron disks. As shown in Fig. 3, the zinc may be cut into washers Z of suitable size and strung upon the bolts B, Fig. 4f, and between the disks of sheet-iron; or, again, the

Zinc sheet Z may, as in Figs. G and 7, be circular in form, with its interior portion removed, and the bolts passed therethrough. Sometimes I construct the core of alternate plates of sheet-iron and Zinc, as indicated in Fig. 5. 6o

The thin scale or tllm before referred to upon the sheet-iron forms an adherent layer of a material which'is an insulator of electricity and constitutes the natural scale or film ot' iron oxide whichis produced in anneal- 65 ing or heating the sheet-iron in the ordinary process of manufacturing the same. As this iilm forms a hard adherent coating,it may be rmly compressed without damage when the plates of sheet-iron and non-magnetic metal 7o are clamped by bolts. This lm constitutes a protection against the formation of local electric currents parallel to the armature-shaft.

The chief cause of heating of armatures is not so much due to currents produced paralof the disks, according to the character of the 8o iron employed, and in other cases the result of the disks moving in an intense magnetic field and the consequent crowding of the lines of force.

By the employment of thin plates of zinc or other non-magnetic metal as an insulator for this magnetic leakage the heating effects mentioned are largely overcome. The disks of sheet-iron and zinc can be bolted together firmly, and there is thus formed a solid struct- 9o ure, which is not liable to become loose or shaky, as is the case when paper or other vegetable material is employed as au electrical or magnetic insulator between the plates.

I am aware that it has heretofore been pro- 9 5 posed to build up the cores of armatures or other electrical apparatus from thin plates of iron secured together, but magnetically insulated from one another by interposed instilating material, such as asbestus, hard rubroo ber, wood, paper, or other similar substance, which, besides being non-magnetic in character, is an electrical insulator, and will prevent the formation ot the electric currents parallel to the armature-shaft. I am also aware that it has been before proposed to use tin or other non-magnetic metal as the magnetic insulator; but in such cases it has ordinarily been proposed to use the tin or zinc as a thin coating` or plating upon the sheet of iron. This renders necessary a special preparation of the iron plates to be used in building up the core, and besides may not in all cases form an etlicient magnetic insulator. Another 0bjection to this construction of the core is that in order to form a film or plating of the metal upon the iron it is necessary that there should be no scale or insulating film between the film of non-magnetic metal and the iron itself, so that it becomes necessary to provide other means for electrically insulating the plates from one another.

lVhat I claim as my invention isl. An iron core for electrical apparatus,built up from plates of sheet-iron liavinga thin adherent scale or coating of hard insulating substance formed naturally in the process of manufacturing sheet-iro11, as described, and thin interposed distinct separating-plates of zinc, tin, or other non-magnetic metal, all secured together as a solid structure by any suitable means.

2. An iron laminated core for electrical apparatus, composed ot a series of plates of sheet-iron, each having a thin hard adherent coating of an insulating natureand mechanically separated from other plates by interposed metal plates or Washers of some nonmagnetic metal, the Whole being secured together by bolts to form a solid structure.

Signed at Lynn, in the county of Essex and tate of Massachusetts, this lst day of August, A. D. 1889.

ELIHU THOMSON.

Witnesses:

JOHN W. GIBBoNnY, A. L. ROHRER.

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