US3609657A - Electrical connector - Google Patents

Abstract

A connector for use with electrical cables comprising a cablereceiving body having two binding screws threaded through respective openings in a flat sidewall of the body and positioned to exert pressure on opposite sides of the longitudinal axis of a cable received in the body.

Description

United States Patent lnventor Harris I. Stanbaek Lexington, Ky. Appl. No. 864,421 Filed Oct. 7, 1969 Patented Sept. 28, 1971 Assignee Square D Company Park Ridge, 111.

ELECTRICAL CONNECTOR 7 Claims, 3 Drawing Figs.

US. Cl 339/272 R, 24/125 N, 85/1 SS, 151/70, 287/118 Int. Cl H0lr 11/10 Field of Search 339/263, 272; 85/1 SS; 151/70; 287/5208, 118, 189.36; 24/125 N, 135 N [56] References Cited UNITED STATES PATENTS 2,222,156 11/1940 Rowe 339/272 FORElGN PATENTS 502,131 5/1954 Canada 339/272 R Primary Examiner-Joseph H. McGlynn Attorneys-Harold J. Rathbun and Paul J. Rose ABSTRACT: A connector for use with electrical cables comprising a cable-receiving body having two binding screws threaded through respective openings in a flat sidewall of the body and positioned to exert pressure on opposite sides of the longitudinal axis of a cable received in the body.

PATENIED SEPZB \sm FIGURE FIGURE 3 FIGURE 2 IN V EN TOR.

. ELECTRICAL CONNECTOR This invention relates to electrical connectors, and more particularly to solderless connectors of the heavy-duty type for use with copper or aluminum cables and wherein at least two binding screws are threaded into a connector body for exerting pressure on a cable received in an opening in the body. The invention is disclosed as embodied in a connector suitable for use as a terminal lug wherein a cylindrical bore in a body portion receives a cable. In accordance with the invention, binding screws for clamping the cable are threaded through respective openings in one sidewall of the body and have suitably contoured inner faces bearing against the cable at locations spaced along and on opposite sides of the longitudinal axis of the cable.

Conventional electrical connectors of the binding screwtype are subject to certain disadvantages. For example, when a cable is received in a circular bore in a connector body and a single large binding screw is used as the clamping means, a random distribution of compressive force results and can produce a mechanical connection of inadequate strength. This is because much of the tightening torque of a large binding screw is expended on frictional forces which reduce the unit pressure. The unit pressure is thus often insufiicient to break down oxides formed on the cable, resulting in poor currentcarrying capacity. Therefore, the use of either one or two large binding screws can result in an inadequate mechanical connection and an inefficient electrical connection.

Although the use of the two smaller binding screws aligned along the longitudinal axis of the cable and threaded through openings located in one wall of the connector produces higher unit pressure for clamping purposes and increases the electrical and mechanical efficiency of the connection, some undesirable features are still present. When aligned smaller screws are used, the width of the surface area of the conductor which is subjected to clamping pressure is reduced thereby resulting in a tendency for the individual strands of the cable to creep or cold-flow away from the clamping force into the available space in the bore thereby reducing the efficiency of the connection. Further, the efficiency of the connection becomes a function of cable size and restricts the usage of the connector to a limited range of cable sizes.

The above limitations are alleviated and additional advantages accrue when, in accordance with the invention, two longitudinally spaced binding screws of relatively small size have their axes respectively on opposite sides of the longitudinal axis of the bore in the connector body and their peripheral portions overlapping the longitudinal axis of the bore. Two binding screws which are so located provide intimate contact of relatively high unit pressure across a major portion of the width of the surface of the cable engaged by the screws even when relatively small cables are used, and reduce the tendency for cold flow or creep by substantially limiting the amount of space available for movement of the cable strands. Further, the turning of the two screws provides a twisting action in opposite directions on the cable strands and imparts a torsional component of force to the clamping pressure. The torsional force is in addition to the axial force provided by the binding screws. In addition, the two binding screws have been found to provide a clamping action which is effective throughout a much larger range of cable sizes, for example, from as small as a AWG size 000 to 750,000 circular mils,.than is possible with prior connectors having a single or two aligned binding screws.

Accordingly, it is an object of the invention to provide an improved connector not subject to the above-mentioned disadvantages.

A further object is to provide a connector providing improved mechanical strength and electrical contact with multistrand conductors or cables.

A further object is to provide an improved connector for use with cables of various circular mil areas.

A more detailed object is to provide an improved electrical connector for multistrand cables including a body portion having a circular bore for receiving an unsheathed end of a cable, and clamping means to secure the unsheathed conductor end in said bore, the clamping means comprising two binding screws received in threaded openings passing through one wall of the body portion and opening into the bore with the axes of the openings disposed respectively on opposite sides of the longitudinal axis of the bore.

The above and additional advantages of this invention will become apparent from the following specification wherein reference is made to the drawings, in which:

FIG. 1 is a perspective view showing the improved connector with a conductive cable secured therein;

FIG. 2 is a top plan view of the assembled connector and cable of FIG. 1 with portions of each of a pair of binding screws broken away to show the upper surface of the cable; and

FIG. 3 is an end view of the assembled connector and cable looking generally from the left of FIG. 1.

Referring to the drawings, the improved connector is indicated generally at 10 and comprises a lug portion 12 provided with a centrally located aperture 14 which may receive a holding bolt or similar securing device (not shown), and an enlarged body portion 16 integral with the lug portion 12 and having a bore 18, preferably circular, for receiving an unsheathed end portion 20 of a multistrand electrical conductor such as a cable 22. As shown, the lower face of the lug portion 12 is coplanar with the lower face of the body portion 16 and its upper face is above the lower periphery of the bore 18 thereby to define a shoulder 12a which serves as a stop for the cable 22. The lug and body portions are preferably copper or aluminum.

Two binding screws 24 are received respectively in threaded openings 26 extending through an upper wall 28 of the body portion 16 and opening into the bore 18 as indicated best in FIG. 3. The axes of the openings 26 for the binding screws 24 are longitudinally spaced from each other along the body portion 16 and are located respectively on opposite sides of the longitudinal axis of the bore 18. Preferably, the spacing of the axes of the openings and the diameters of the openings are such that marginal areas of each of the openings intersect a plane extending through the longitudinal axis of the bore 18 and normal to the wall 28, and are spaced only slightly from each other longitudinally of the axis of the bore. The peripheries of the openings 24 adjacent the respective side faces of the body portion 16 are substantially in alignment with the lateral extremities of the bore 18.

The outer end faces of the screws 24 have a central hex agonal recess 30 which may receive an Allen wrench (not shown) for turning the binding screws 24 relative to the body portion 16 so as to selectively clamp and unclamp the inner faces of the screws 24 from the end portion 20 of the cable 22.

The positioning of the screws 24 eccentric to the longitudinal axis of the bore 18, as previously described, permits the screws to encompass all or a relatively large portion of the width of the bore 18 so as to reduce the size of the airgaps about the cable portion 20 which would allow creep or coldflow of the cable strands and result in a reduction of clamping pressure. As explained, hereinbefore, the two relatively small screws 24 exert a greater clamping force per unit area than would a larger screw, and offer a substantial advantage when used to clamp cables which are sufficiently large in circular mil area to occupy a major portion of the bore 18. Preferably, the contours of the inner end faces of the screws 24 are shaped as indicated at 31 in FIG. 3 to approach the curvature of the lower portion of the bore 18. Hence, the screws 24 intimately contact a major portion of the upper surface of the cable portion 20 irrespective of its size, and can exert adequate clamping force on cables that are small relative to the size of the bore 18.

What is claimed is:

1. An electrical connector for multistrand cables, said connector comprising a body portion having a bore for receiving an unsheathed end of a cable, and clamping means to secure the unsheathed cable end in said bore, said clamping means the bore.

2. An electrical connector as claimed in claim 1 wherein the bore in the body portion is substantially circular in transverse cross section.

3. An electrical connector as claimed in claim 1 wherein the axes of the openings are so positioned and the diameters of the openings are such that respective marginal areas of each of the openings intersect said plane.

4. An electrical connector as claimed in claim 3 wherein the edges of the openings are spaced only slightly from each other longitudinally of the axis of the bore.

5. An electrical connector as claimed in claim 1 wherein a portion of said wall of the body portion has a substantially flat outer surface and both openings pass through said portion.

6. An electrical connector as claimed in claim 5 wherein the outer peripheral portions of the openings laterally of the axis of the bore are substantially in alignment with the respective lateral extremities of the bore.

7. An electrical connector for multistrand cables, said connector comprising a body portion having a bore for receiving an unsheathed end of a cable, and clamping means to secure the unsheathed cable end in said bore, said clamping means comprising a plurality of binding screws received respectively in a plurality of threaded openings passing through a wall of the body portion and opening into the bore, axes of the openings being spaced from each other both longitudinally and transversely of the bore, and the diameter of the openings being less than the width of the bore but not substantially less than the product of the width of the bore and the reciprocal of the number of openings.

Claims (7)

1. An electrical connector for multistrand cables, said connector comprising a body portion having a bore for receiving an unsheathed end of a cable, and clamping means to secure the unsheathed cable end in said bore, said clamping means comprising two binding screws received respectively in two threaded openings passing through a wall of the body portion and opening into the bore, the axes of the openings being spaced from each other longitudinally of the bore and positioned closely adjacent to each other respectively on opposite sides of a plane containing the longitudinal axis of the bore, and the diameter of the openings being less than the width of the bore but not substantially less than one-half the width of the bore.

2. An electrical connector as claimed in claim 1 wherein the bore in the body portion is substantially circular in transverse cross section.

3. An electrical connector as claimed in claim 1 wherein the axes of the openings are so positioned and the diameters of the openings are such that respective marginal areas of each of the openings intersect said plane.

4. An electrical connector as claimed in claim 3 wherein the edges of the openings are spaced only slightly from each other longitudinally of the axis of the bore.

5. An electrical connector as claimed in claim 1 wherein a portion of said wall of the body portion has a substantially flat outer surface and both openings pass through said portion.

6. An electrical connector as claimed in claim 5 wherein the outer peripheral portions of the openings laterally of the axis of the bore are substantially in alignment with the respective lateral extremities of the bore.

7. An electrical connector for multistrand cables, said connector comprising a body portion having a bore for receiving an unsheathed end of a cable, and clamping means to secure the unsheathed cable end in said bore, said clamping means comprising a plurality of binding screws received respectively in a plurality of threaded openings passing through a wall of the body portion and opening into the bore, axes of the openings being spaced from each other both longitudinally and transversely of the bore, and the diameter of the openings being less than the width of the bore but not substantially less than the product of the width of the bore and the reciprocal of the number of openings.

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