US2247041A - Wire connector - Google Patents

Description

June 24, 1941. M. o. BERGAN' WIRE CONNECTOR Filed Feb. 9, 1940 INVENTOR Patented June 24, 1941 NITED STATE-5 WIRE CONNECTOR Martin D. Bergan, Westfield, N. 3., assignor to The Thomas & Betts 00., Elizabeth, N. 1., a corporation of New Jersey Application February 9, 1940, Serial No. 318,038

2 Claims. 173-269) The invention relates to.a wire connector of the type commonly called a bonding. jumper. A jumper usually includes a pre-selected length of wire or cable at each end of which there is joined a terminal means having a screw hole or other means to be used for securing the jumper in service position with some other structure.

An object of the invention is to produce a wire connector having a new electrical terminal member in the form of a stepped-size tubular lug which is specially formed in combination with a stranded flexible wire conductor, wherein said wire strands are reinforced and supported in a new manner within said terminal member and so arranged as not only to resist breakage where the conductor, joins the member but likewise the latter has a wider terminal end than usual, thereby adaptingit to be pierced with a large hole, without impairing its strength, for the reception of a standard bolt or screw by whicha large-area contact and more rugged connection are established with a bus bar or other structure and parts requiring electrically bonded connections.

Other objects of the invention will be more apparent from the following description taken in connection with the accompanying drawing, illustrating a preferred embodiment of the invention, in which:

Figure 1 is a view of the separate parts of the wire connector or bonding jumper before assembly with each terminal tube in position ready to be slipped over its respective end of the wire strands.

Figure 2 is a view showing each terminal tube slipped over its respective end of the wire.

Figure 3 is an end view of the jumper as far as it is completed as shown in Figure 2.

Figure 4 shows the bonding jumper with the larger ends of each terminal tube pressed or mashed together to form a wide area terminal means adapted to receive a screw or bolt of standard size.

Figure 5 is a sideview of the bonding jumper of Figure 4, constituting a new combination of terminal lug and stranded conductor.

Figure 6 shows thecompleted bonding jumper with the projecting ends of the strands of the wire trimmed off.

Figur 7 is a section through one of the terminal means of the bonding jumper secured in position by a terminal screw and resisting the crushing efiect of the screw head, as well as supporting the wire strands against breakage where they join to the terminal member.

The wire connector or bonding jumper utilizes a terminal means or part which is initially a tube or tubular lug piece l0 having a large diameter H at one end 01' length'thereof and a small diameter I2 at the other end or length thereof,

thus forming a tubular lug of stepped size. The

small diameter end of the tubular piece has a wire bore l3 which approximates the diameter of the stranded wire or cable l4 so that the end of the wire may be easily received therein with a close or snug flt.

The tubular piece may be formed in any suitable manner. For example, a small tube or pipe may be selected having a diameter which corresponds with the desired diameter for the small end l2 of a terminal means for receiving the end of wire it, and this small tube then has one end enlarged to the desired large diameter end ll. Again, a tube may be selected having the desired large diameter and one end thereof is then swaged to the desired small diameter to i'orm the terminal means, A third method is to use a tube of intermediate-diameter and enlarge one end or length II to the proper large diameter and swage the other end or length l2 to the desired small diameter to fit the wire to be received therein. These methods particularly described produce a seamless terminal tube.

A terminal tube or'tubularlug piece of stepped size, that is, two diameters in this instance, is slipped over each end oil-the wire I! with the larger diameter at the outer ends. The wire preferably projects slightly=beyond the ends of the tubular piece as shown in Figure 2. This is merely to assure-that the entire flattened end or length of the terminal means will grip the wire. The wire strands l4 have a close fit in the small tubular end l2 and initially a loose fit in the large tubular end ll.

The smaller diameter end l2 of the terminal tube may, if desired, be given an indentation or crimping I! for preliminarily securing the same to the wire. The larger diameter end of the terminal tube is then flattened from its outer end back to a flattening line l9 extending across its conic portion and simultaneously the end of the wire or cable 14 is also flattened. The strands spread out within the flattened end 2| for completely and uniformly filling same and are firmly gripped thereins Consequently, the flattened out strands of the wire will extend the entire width of the flattened interior.

Means are provided to secure the terminal means to some other structure, such as a hole l8 which may be drilled, punched, or otherwise provided in the flattened end or portion, thereby transforming the terminal tube into a terminal means. The ends of the strands of wire projecting from the flattened end of the terminal means may be trimmed even with the end thereof to leave a neat appearing bonding jumper.

Usually a bonding jumper or jumper wire includes a predetermined length of wire with a terminal means at each end thereof. It is to be understood, however, that the jumper wire may have a terminal piece, as described, at oneend only, and the other end may have no terminal means whatever. It is also clear that the jumper wire may have a terminal means at one end, as described herein, and the other end may have a terminal means of any other suitable construction.

In the method of forming the terminal piece upon the end of the wire, the larger diameter end of the tubular piece l0 may be flattened in any suitable way such as by mashing it between the jaws of a punch press, or it may be flattened by passing it a desired distance between rollers so that in the latter case the larger diameter end is rolled flat.

sirable, although not essential, that one of the flattened faces 20 be tangent with, or approximately tangent with, the outer surface of the small diameter end I! as illustrated in Figures 5 and 7.

This new terminal satisfactorily combines with stranded wire by which to produce rugged electrical bonding jumpers for all manner of grounding installations and wiring work; This new combination stranded conductor and terminal lug endures against vibrational strain and hard service, and the wire II is not likely to crystallize and break from or at the tubular lug l0.

Such improvement in function, with resulting prolonged life, is attained by reason of the fact that the small tubular end or length l2 envelopes the wire strands for a distance back from the large flattened end or length l I, that is. for a distance back from the transverse flattening line I! (Figure 4) defining the terminus of the flatarea. The small tube length. l2, which snugly (though not tightly) embraces and reinforces the wire strands against vibration, insures against eventual crystallization and prevents rupture of the strands in whole or part.

The juncture of the small length I! with the Whichever method is used for flattening the larger diameter 'end, it is delarge length ll of the tubular contact It! is integrally formed through a conically-shaped portion serving to step-up the tubing from small to large size. Thus the conic formation, substantially centrally located=in the tube l0, re-

ceives the flatteningtool or press, thus dispos-q ing the flattening or swagingcrimp line l-,9

transversely across or through the cone. The result is that the transverse pinch or crimp line is localized across or through the juncture cone and disposed far back from theouterextremity of the small tube l2.

Another characteristic feature J resides in the fact that a certain amount of annular clearance initially exists between the wire l land the inside tubular wall before the line l9 (Figure 4) of flattening pressure is applied. This annular clearance within the'tapering o'r conic portion allows the two-stage diameter tube to be deformed by pressure without cutting orforming a break line or 'seam across the tube. It is to be seen that the tube initially yields under the flattening pressure and has room or annular space around the wire to permit a partial flattening before the tube walls begin to squeeze the wire in the region of the swaging or flattening line I9. The delicate wire strands are preserved against a shearing tendency, although subjected to the heavy swaging and flattening tool used in re-' ducing the terminals to the characteristic formation shown.

It follows therefore, that the delicate strands l4 cannot vibrate or move at the transverse crimping or pressure line, which is the critical point where prior art devices are subject to rupture. This invention is found to solve the problem by not only locating the critical pressure line I9 so as to support the wire strands at a point remotely from the pressed area of the terminal but likewise has the advantage of a wide terminal end. a I

Regarding the last named feature, the size of the larger tube' length ll being comparatively larger than the other length 12, provides a widearea terminal end 2! when it is flattened. The

width of this flattened end 2| is greater than conventional terminal pieces, for given sizes of terminal material, and thus is afforded adequate material or stock through which to punch a full size hole l8. Consequently, a larger bolt or screw can be used which results in a more rugged electrical connection with a bus bar or the like. The centrally disposed conic-portion provides these several advantages and the wide end with larger size screw hole affords a maximum of .electrical contact area between the terminal and bus bar with which it is connected.

Thisinvention is presented to flll aneed for a new and useful wire connector. It is understood that various modifications in construction, operation, use and method, may and often do occur to those skilled in the art, especially after benefiting from the teachings of an invention. and that this disclosure with its appended claims are descriptive of the principles but not limited to the illustrated embodiment of the invention. a

What .is claimed is:

1. An electrical wiring connector comprising. in combination, a tubular terminal of steppedsize formation providing two lengths of different diameters, thereby constituting small and large tubular lengths merging integrally through a conically-shaped portion substantially. intermediate the extremities of the terminal, and a stranded wire conductor mounted with a snug,

fit-in the small tubular length-and extended into the large tubular length with a loose fit, 1

on the wide flattened end establishing an anchor age and positive electrical connection with the wire strands, the pressure aforesaid also pro-' ducing. a flattening line'extending across the V (sonically-shaped portion substantially transversely of its axis, whereby the wire strands are supported by the small tubular length to endure vibration by restraining said strands against bending motion at the flattening line.

2. An electrical wiring connector comprising,

in combination, a tubular terminal member of stepped-size formation having two tubular lengths of different diameters, thus providing small and large tubular lengths merging integrally through a conically-shaped portion disposed between the extremities of the member, and a stranded wire flexible conductor mounted with a-snugly supporting fit in the small tubular length and extended into the large tubular length with a loose fit, the large tubular length and the loose wire strands therein being reduced by pressure to form a flattened terminal end and by reason of its initial diameter being comparatlvely greater than the other tubular length, thereby affording adequate stock for a sub-- stantially large perforation punched through it for the reception of screw means adapted for use in anchoring the terminal end, with its to establish an anchorage as well as a positive 10 large-area contact, against a bus bar or the like.

electrical connection with the wire strands, the pressure aforesaid also producing a flattening MARTIN n. BERJGAN.

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