US2060913A - Electrical conductor - Google Patents

Description

NOV. 17, 1936. l WEAVER 2,060,913

ELECTRICAL CONDUCTOR Filed July 7, 1934 F/G. 4. A F16.

/NVENOR L. 1 WEAVER ATTORNEY Patented Nov. 17, 1936 PATENT OFFICE ELECTRICAL CONDUCTOR Leo L. Weaver, Cranford, N. J., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of NewYork Application July 7, 1934, Serial N0. 734,082

1 Claim.

This invention relates to electrical conductors and more particularly to` multiple conductor cords or cables.

The cords used to connectr a telephone receiver to the base of the instrument and the base to the bell box must be of sutlicient length and exibility, especially in the case of a desk telephone to permit of convenient use over a relatively wide area. At the same time in some cases it is preferable that these cords should not be in the way when the instrument is not in use. Similar considerations apply to the power cords used to supply current to lamps, fiat irons, toasters and other electrical devices. Many devices in the Iorm of variously coiled and shaped spring wires to be applied to or over such cords have been suggested.

An object of the invention is to provide a self coiling cord or conductor which is so constructed as to form itself into a neat and compact coil when not under tension without the application thereto of any extraneousl means or device not normally included in the structure of such conductors or cords, and which shall nevertheless yield easily to tension tending to elongate the coil. In one embodiment of the invention, one or lmore of the three metallic conductor strands of the customary telephone cord is made of some material such as a phosphor bronze alloy, which combines both satisfactorily high `electrical conductivity and mechanical elasticity, and is formed as a flattened tape wound in a resilient helix or Fig. 1 is a plan view of a length of three con-A ductor cord constructed and formed in accord- 50 ance with the invention;

Fig. 2 is a view thereof in side elevation; Fig. 3 is an enlarged sectional View on the line '3f-3' of Fig. 2; Fig. 4 is a view similar to Fig. 1 of a modified 55 form; f

rection of its coil axis and tends to resume its Fig. 5 is a view similar to Fig. 2 of another modified form; I

Fig. 6 is lan enlarged sectional view on the line 6-6 of Fig. 5, and

Fig. "I is an enlarged sectional view of a third modication.

The embodiment of theinvention disclosed in Figs. 1, 2, and 3 comprises threeconductors 20, 2|, and 22. These are flat tapes of rectangular cross section coiled in a resilient cylindrical helix whose curvature is substantially in the plane of the tapes. The tapes are made preferably of a phosphor bronze alloy or other material having both satisfactory electrical conductivity and4 mechanical elasticity.

Themiddle tape 2| is individually covered with a braided protective and insulatingsheath 23 of textile libres, and the three tapes together are covered with a similarouter sheath 24.

Instead of coiling the cord in a helix as shown in Fig. 2, it may in some cases be preferable to coil it as a fiat resilient spiral as shown in Fig. 4. In either case the coiled form is held and sustained by the coiled ilat conductors and not by any added member.

Figs. 5 and 6 discloses a modiiied form of the invention in which there is only one conductor in the cord and in which the cross sectionl of the conductor is elliptical or oval and is formed into al helix with the principal curvature in the plane of the greatest cross section-dimension of the conductor.

A cord or cable made and formed in accordance Awith the invention may have any number oi conductors associated together provided that one of the conductors be elastic and have a cross section of greater dimension in one of two mutually perpendicular directions than in the other, so that if the cord beformed-as a coil with its curvature in the plane of the greater cross section dimension of the attened conductor, it will flex easily across that plane but will resist flexure in the plane.

'Ihus Fig. 7 is a cross section of a cord embodying the invention in which a singleflat tape conductor 2| is combined with two ordinary round or stranded conductors |20 and |22 and the whole may be coiled in a resilient spiral or helix with the curvature in the plane of thetape 2|.

One advantage of the construction disclosed in Figs. l, 2, and 3 is the saving in covering material. The fiat tape-like conductors enclosed in thesheath 24 are held thereby against relative lateral displacement, and inparticular conductors 20 and 22 cannot slide around conductor 2l and make contact with each other.

Hence for mutual insulative separation of the three conductors it is necessary only to cover themiddle conductor 2| individually, whereas ii all three were circular in cross section, no one could be relied upon to separate the other two. The same is true of the construction shown in Fig. 7.

In the disclosure above it is suggested that theconductive strands 20, 2|, and 22 be made of phosphor bronze. This is a preferred c0nstruction since such alloys are at the same time highly electrically conductive and also highly mechani cally elastic. The invention is not, however, coniined to this material as in some instances other materials such as spring brass, some spring steels, certain nickel alloys such as monel, nichrome and the like, and for some uses hard drawn alloys of aluminum could be used.

For simplicity and clarity of statement the phrase substantially ilat" as applied to the cross section of a conductor will hereinafter be used to mean a cross section greater in one direction than in any other. and thus will include oval, elliptical, rectangular but not square, rhombic or rhomboidal cross sections and the like. Also the phrases coiled in the plane of the conductor" or coiled in the plane of the strand" will be similarly used to mean coiled so that the curvature of coiling. is substantially `in or wallel to a plane passing through the conductor or strand in the direction of the greatest dimension of the cross section of the conductor or strand.

'I'he embodiments of the invention herein disclosed' are illustrative merely and may be modiiled and departed from in many ways without departing from the spirit and scope o! the invention as pointed out in and limited solely by the appended claim.

What isclaimed is:

An electrical conductor cord comprising three strands each a unitary combined conductor and coiling spring and each of material both` electrically conductive and mechanically elastic and each formed with a substantially flat cross section and the three cross sections being mutually parallel, a sheath of insulating material on the middle strand, and a sheath of insulating material over the whole, the whole conductor cord being coiled in the plane oi' the ilat strands, whereby the coiled conductor is easily elastically deformable under stress along the axis of the coils thereof and tends to return to its coiled :form when released from stress.

LEO L. WEAVER.

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