US2722562A - Electric cables - Google Patents

Description

Nov. 1, 1955 E. E. MOILVEEN 2,722,562

ELECTRIC CABLES Filed July 29, 1950 INVENTOR. EDWAQD E. MC'JL WEE/V BY a (j ATTOQA/EY United States Patent Oflice 2,722,562 Patented Nov. 1, 1955 ELECTRIC CABLES Edward E. McIlveen, Upper Montclair, N. J., assignor to The Okonite Company, Passaic, N. J., a corporation of New Jersey Application July 29, 1950, Serial No. 176,712

1 Claim. (Cl. 174-107) My invention relates to low-voltage, multi-conductor, electric control cables and has for one of its objects to provide an electric cable embodying a barrier against attack by termites and other insects, gophers, rodents, and other small animals.

More specifically, my invention provides an electric cable having a wall of primary insulation, an outer, nonmetallic sheath, and an intermediate, flexible, metallic sheath, providing the barrier above referred to. The metallic sheath is extremely flexible and exceptionally high in compressive strength, enabling a very thin sheath to be used.

In the accompanying drawing I have illustrated one embodiment of my invention in side elevation with parts broken away at different levels.

Referring to the drawing in detail, 2 designates the several conductors of the cable, individually insulated with rubber and rubber-like compounds. These conductors are cabled together with rubber fillers 4, to provide an assembly round in cross section.

Wrapped about this assembly is one or more layers of asbestos-neoprene bedding tape 6.

Wrapped tightly about the non-metallic tape 6 is a metal barrier tape 8. This tape is preferably bronze, although other metals, with the exception of lead, may be acceptable. The tape 8 is provided with longitudinally extending corrugations 10. The corrugations are parallel to each other, and each corrugation extends continuously the length of the tape.

The corrugations are conveniently formed as the tape is being wrapped helically about the insulated conductor assembly by substituting two cooperating grooved rollers for one plain guide roller on a conventional taping head.

The barrier tape is helically wrapped about the conductor assembly with suflicient overlap so that one or more of the corrugations at the edge of one turn or wrap of the tape will overlap and interlock with the same number of corrugations at the edge of the underlying turn or wrap. It will be observed also from the drawing that, in applying the barrier tape, the bedding tape 6 fills the corrugations on the inner face of the barrier tape. This provides an interlock and seal throughout the length of the cable.

Over the barrier tape 8 I apply a neoprene compound sheath 12, and over this sheath I wrap a neoprene compound friction tape 14.

The assembly is finally vulcanized.

I find that a cable constructed as above described is very flexible, the longitudinally corrugated, helically applied metal barrier tape being sufiiciently flexible to permit the cable to be bent around a radius close to that of its own diameter without buckling of the barrier tape and without damage to the insulation.

l find also that, by corrugating the barrier tape longitudinally and wrapping it helically about the conductor assembly, the cable is very high in compressive strength, permitting the use of lighter-gauge metal for the tape than where a flat tape is employed.

It is to be noted that the covering over the barrier tape bonds securely to the barrier tape and, of course, provides corrosion protection to the tape as well as an allpurpose covering, permitting the cable to be installed directly in the earth, in conduit, aerially, or on rocks.

The absence of fibrous material within the cable should be noted. This avoids wicking.

It is to be understood that changes in construction may be made without departing from the spirit and scope of my invention.

What I claim is:

An electric cable comprising an insulated conductor; a layer of non-metallic bedding tape about the conductor insulation; a flexible, metallic barrier tape about said bedding tape; and an outer, non-metallic, rubber-like, flexible sheath structure; said barrier tape being longitudinally corrugated, each corrugation extending continuously the length of the tape, and the tape being helically wrapped about the bedding tape, with the material of the bedding tape filling the corrugations on the inner face of the barrier tape and with a plurality of the corrugations of one turn of the barrier tape interlocked with a plurality of the corrugations of the next turn, the barrier tape being bonded to said outer, non-metallic sheath structure and unbonded to the bedding tape.

References Cited in the file of this patent UNITED STATES PATENTS 463,107 Degenhardt Nov. 10, 1891 1,459,487 Witzenmann June 19, 1923 1,771,120 Hunter et al. July 22, 1930 1,781,521 Palmer et al Nov. 11, 1930 1,993,424 Weber .d Mar. 5, 1935 2,121,942 Barrett June 28, 1938 2,216,435 Eckel Oct. 1, 1940 2,433,081 Wilkoff Dec. 23, 1947 FOREIGN PATENTS 254,414 Germany 1912 36,256 France Jan. 23, 1930 764,175 France Feb. 26, 1934 464,794 Great Britain Apr. 26, 1937 827,672 France Jan. 28, 1938 OTHER REFERENCES Bell Lab. Record, vol. XXVI, No. 11, November 1948. (Copy in Division 65.) Pg. 442 relied upon.

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