US3407263A - Flexible electrical conductor - Google Patents

Description

Oct. 22, 1968 N. K. MILLER 3,407,263

FLEXIBLE ELECTRICAL CONDUCTOR Filed Dec. 20, 1967 United 3,407,263 Patented cc t 22, .1968

, a ,7 modified conductor 'structure of the present invention,

3,407,263 1 also broken away for clarity.. FLEXIBLE ELECTRICALCONDUCTOR Norman K. Miller, Havertown, .Pa., assignonto Miller I Brothers, Concordville, Pa., a partnership 1 Continuation-impart of application Ser.'No. 370,581," May 27, 1964. This application Dec. 20,1967, Ser. No."692,206 r '6 Claims.'(GI.-17.41-13)'- ABSTRACT F, DIscijlosjURi': i1 v "A flexible electrical-conductor structure wherein'a conductor'of'aluminum foil is immediately protected by a contiguous layer of flexible terephthalate, a' woven' fabric being in intimate engagement with the terephthalate, and

an insulation covering a foan'i lieiiig adhesively secured to the woven fabric.' I a In the field of conductor structures, there are certain conditions of use wherein such structures must withstand repmted impact and flexure without failure or diminution of useful life. While these features may be advantageous in many circumstances, they are absolutely essential in the use of conductor structures as treadles for persons or vehicles, safety edges for doors, and many others.

Prior to the instant invention, these and similar applications were subject to frequent malfunction by fracture or other failure of conductors, or required extremely expensive conductor structures or other forms of power, such as pneumatic and hydraulic.

Summary Accordingly, it is an important object of the present invention to provide a unique conductor structure which is relatively freely defiectable and flexible, while possessing greatly enhanced resistance to impact and damage from flexure.

It is another object of the present invention to provide a conductor structure having the advantageous characteristics mentioned in the preceding paragraph which produces extremely low power loss while utilizing relatively inexpensive conductor material, and effectively protects the conductor material from the effects of repeated impact and flexure to greatly enhance its useful life at substantial savings in cost.

Other objects of the present invention will become apparent upon reading the following specification and referring to the accompanying drawings, which form a material part of this disclosure.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, which will be exemplified in the construction hereinafter described, and of which the scope will be indicated by the appended claims.

Brief description of the drawings FIGURE 1 is a perspective view showing a conductor structure of the present invention, broken away for clarity.

FIGURE 2 is a transverse section taken along the line 2-2 of FIGURE 1.

FIGURE 3 is a perspective view showing a slightly I Description of the preferred embodiments Referring now more particularly tothe drawings, and specifically to FIGURES 1 and 2 thereof, the conductor structure is there generally designated 10, and, for purpQse'sLof illustratiom is shown as, single conductor structure. Centrally of the conductor structure '10 n15 conductor'proper, designated 11, advantageouslyfabricated of'aluminu'in foil in strip form, In practice, conductor strips l liof aluminumfoil'have beenemployed in thick- ,nes'ses between .001 and .005 inch Th'e width of thealuminum-foil conductor strip 11 may beas desired, /z ineh having been found satisfactory for certain safety-dooredgeuses. H 1 '1 Surroundingtheconductorstrip 11 is a layer 12 of terephthalate, sometimes 'sold ,under the trademark Mylar. The'fte rephthalate[layer IZislsecuredin intimate fface-to-face engagement with the aluminum-foil strip 11 bythermoplastic adhesion, so that the physical characteristics ofthe terephthalate are effectively imparted tothe ,alur'ninum strip. g Surrounding the terephthalate is a layer of woven fabric 13, advantageously asbestos. The asbestos 13 is also secured in intimate face-to-face engagement throughout with the terephthalate by thermoplastic adhesion. In this manner, the physical qualities of the asbestos layer are effectively imparted, through the terephthalate, to the aluminum foil. By this intimate, overall securement of the aluminum-foil strip 11, terephthalate layer 12 and asbestos layer 13, these components function in a unitary manner, the reinforcement in flexure of the terephthalate, and the resistance to puncture and rupture of the asbestos being imparted to the foil strip.

In addition, surrounding the asbestos layer is an insulating covering 14 of a relatively soft, resilient plastic or rubber foam. The foam covering 14 is adhesively secured in intimate facing engagement throughout with the asbestos layer 13 and contributes, in addition to its insulation, resilience to restore the structure to its original condition immediately following impact and flexure. The foam covering 14 is advantageously at least /s inch thick, and of a quality generally called soft or medium soft. The terephthalate may be of a thickness between .003 and .006 inch, it having been found satisfactory to employ terephthalate of .005 inch in thickness. The weight of asbestos may vary, within the limits imposed by the desired flexibility.

In the embodiment shown in FIGURE 3, there is a conductor structure generally designated 10a, which is in many respects similar to the conductor structure 10, but is illustrated as being a two'conductor structure.

More particularly, the conductor structure 10a includes an intermediate or spacer strip 18, which may be of foam, or other suitably flexible material. On opposite sides of the spacer strip 18 are a pair of conductor strips 11a. advantageously of aluminum foil such as the conductor strip 11.

Intimately secured by thermoplastic adhesion in faceto-face engagement with the outer face of each conductor strip 11a is a terephthalate strip 12a. The terephthalate strip 12a may be similar to the terephthalate layer 12, say of a thickness between .003 and .006 inch.

Intimately bonded by thermoplastic adhesion on the outer faces of the terephthalate layers 12a, completely covering the latter, are ,respective layers of woven fabric 13a, advantageously asbestos. On the outer face of each asbestos layer 13a, adhesively secured thereto throughout the faces thereof are covering layers of foam 14a. The upper layer 14a, as shown in the illustrated embodiment, may be of considerable difference in thickness from the lower layer 140. An enciosure or casing 20 may surround the structure 18, 112:, 12a, 13a and 14a.

Thus, the conductor structure of FIGURE 2 defines a two-conductor structure, including a pair of aluminumfoil conductor strips 11a. If desired, the spacer 18 may be of a perforate construction, say'to permit contactbetween the conductor strips 11a upon depression through the spacer.

From the foregoing, it is seen 'that the present invention provides an "electrical-conductor structure which fully accomplishes its intended objects and is well adapted to meet practical conditions of manufacture and use.

Although the present invention has been described in some detail by 'wav of illustration and example for pu'rposesof clarity of understanding, it is understood'tha't certain changes and modifications may be made within the spirit of'the invention and scope of the appended claims.

' 'Whatis claimed is:

aluminum'foil; a layer of'fi'e'xible terephthalate in intimate face-to-face engagement with and thermoplasticaliy secured to said foil to enhance fiexural life of the foil; 21 U3 woven fabric in intimate face-to-face engagement with and thermoplastically secured to said terephthalate on the face thereof remote from said foil to afford increased tear resistance to the foil; and an insulating cover of relatively soft resilient foam material adhesively secured in'intimateface-to-face'engagement with sai-d fabric on the face thereof remote from said terephthalate for affording resilience to the fabriefterephthalate and foil.

2. An electrical-conductor structure according to claim 1, said aluminum-foil conductor being of a thickness between 5001 anduOOSinch: a

3f An electrical-conductor structure according to claim 1, said lteiephthalate being of?! thickness between .003 dw i m p u ,1 -..v =1

4. An electrical-conductor" structure accordin g'to claim 1, said fabric comprising asbestosfor insulating said foam from the heat of said conductor.

5. An electrical-conductorstructure according to claim 1, said foam being at least inch thick.

6. An electrical-conductor structure according to claim 1, saidconductor comprising a pairof spaced aluminumfoil strips and a ilexible SPaCerstrip interposed between saidfoil, strips. t

a. R i sa fl I UNITEl) STATES PATENTS.

423,449 3/1890 Seelv 2 174-117 x 2,875,435 2/1959 McMillan. LEWIS H. MYERS, Primary Examiner. E. giQLljBElt C hi-AssistiimExaminer. v

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