Electrical terminal clamp

[57] ABSTRACT

An electrical terminal clamp has opposed clamping members at least one of which is electrically conductive and between which is adapted to be received an electrical wire covered with pliable insulation, the electrically conductive member having thereon a rigid contact ridge across which the insulated wire is received such that when the clamping members are forced together to squeeze the insulated wire therebetween, the ridge is pressed into the insulation to effect an electrical contact with the wire. The contact ridge feature may be embodied in a generally Ushaped electrical connector equipped to be snapped into position in a prepared aperture in a terminal board, with the clamping members comprising a base web and a nut threaded on a screw engaged on the web, the ridge being pressed in said web so that the nut will be drawn theretoward by tightening the screw.

Claims, 5 Drawing Figures

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PATENTED SEP 2 6 1972

3,694,792

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ATTORNEYS

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ELECTRICAL TERMINAL CLAMP

This invention relates to new and improved electrical terminal clamp devices and is more particularly concerned with such devices in electrical connectors of a 5 type adapted to be mounted on dielectric panels such as binding post boards of the kind employed, for example, for connecting aerial leads in radio and television sets.

Prior connectors for effecting electrical connections ¹⁰with wires, such as aerial leads in radio and television sets, have generally required skinning or stripping off of the insulation at the terminal end of the wire, equipment of the terminal end with spade lugs, and the like; and where the wire comprises multiple strands soldering or tinning of the strands to provide a stable conductor terminal has often been deemed necessary. All of these expedients are time consuming and appreciably increase the costs of manufacture or installation. 20 Further, the skinned or otherwise prepared wire terminals have required expert attention to proper gripping thereof to assure retention, especially against pulling away from the connector. This has often motivated the assembler or technician to overtighten 25 the gripping means. Embrittlement, weakening, smashing or other damaging results are common occurrence.

In television antennas, for example, cutting and smashing of the fine strands of antenna conductor cable normally causes inferior television picture quality. Another disadvantage of prior arrangements, especially those utilizing screw-actuated or applied gripping devices has been liability toward looseness due to vibrations from whatever cause, such as are frequently encountered in operation of the apparatus or due to environmental factors.

An important object of the present invention is to overcome the foregoing and other disadvantages, shortcomings, inefficiencies, and problems inherent in prior structures and to provide a new and improved electrical terminal clamp structure.

Another object of the invention is to provide a new and improved electrical terminal clamp structure which will avoid any need for stripping or skinning the insulation from wire terminals to be gripped thereby.

A further object of the invention is to provide a new and improved electrical terminal clamp having novel means for effecting electrical connection with an electrical wire.

Still another object of the invention is to provide a new and improved electrical terminal clamp in which an insulated wire is adapted to be gripped with unusual security without such pressure as would tend to damage the wire whether the wire be single strand or multistrand.

Yet another object of the invention is to provide an electrical terminal clamp structure in an electrical terminal having new and improved means for snap-in mounting of the same on a supporting panel.

Other objects, features and advantages of the invention will be readily apparent from the following description of a preferred embodiment thereof, taken in conjunction with the accompanying drawing, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts embodied in the disclosure, and in which:

FIG. 1 is a plan view of a mounting panel carrying an electrical connector having a terminal clamp structure according to the present invention;

FIG. 2 is a sectional elevational view taken substantially along the line II—II of FIG. 1;

FIG. 3 is a plan view of the connector of FIG. 1 looking at the opposite end of the connector;

FIG. 4 is an enlarged illustrative fragmentary elevational sectional view taken substantially along the line IV—IV of FIG. 2; and

FIG. 5 is a plan view of the body of the connector as it appears in the blank before it is formed up.

An electrical connector 40 embodying features of the invention is constructed and arranged to be attached to a dielectric panel 41 (FIGS. 1, 2 and 4) having therein a rectangular mounting hole 42 receptive of the connector. By way of example, the panel 41 may be a so-called circuit board, switch board, binding post board, antenna terminal panel or board, or the like. The connector 40 may be mounted on the panel 41 for effecting numerous and varied electrical connections by and between wires of electrical apparatus, such, for example, as for detachable connection of an antenna lead terminal at one face of the panel while one or more circuit wires may be soldered to the connector at the opposite face of the panel.

In a preferred construction, the connector 40 is made from relatively thin sheet metal which is suffi30 ciently stiff to be form-stable under conditions of intended use, but is possessed of characteristics enabling high speed, low cost progressive die forming of the sheet metal part and which after working is substantially resilient for intended purposes. To enable recep35 tion of the connector 40 in the rectangular aperture 42, the connector is provided with a pair of spaced parallel similar legs 43 which may be coextensive but which may be of different lengths, but in any event are con40 nected together in a one-piece structure by a connecting or base web 44 at one of their ends, in a generally U-shape arrangement, and dimensioned to be received in complementary relation within the hole 42, with the outer faces of the legs in close slidable relation to op45 posite sides of the hole while the respective opposite edges of each of the legs fit in close slidable relation to the remaining edges of the hole. Thereby, mounting of the connector 40 in the hole 42 is readily effected by inserting the free ends of the legs 43 into the hole and 50 pushing the connector into position. To facilitate this, the terminal portions of the legs are preferably toed in toward one another generally convergently and thereby provide lead-in cam respective surfaces 45.

Means on the connector 40 for maintaining it in posi55 tion against unintentional displacement from the hole 42 comprise at each side of each of the legs, and suitably spaced from the web 44, a laterally extending stop shoulder 47 which faces in the direction of the major longitudinal extent of the contiguous leg edge, ⁶⁰ that is toward the free end of the leg. All of the shoulders 47 are in the same plane so that they will make substantially uniform contact with the surface of the panel 41 from which the legs 43 are inserted into the ₆₅ hole 42. The shoulder means engageable with the opposite surface of the panel comprise respective automatically acting resilient locking shoulder lugs or tabs 48 on the legs 43 and each provided with a locking

3,694,792 edge 49 which is outwardly off-set relative to the associated leg and faces generally toward the plane of the shoulders 47 and spaced therefrom equal to the thickness of the panel 41 with just enough tolerance for easy snap-in mounting of the connector.

Desirably, the locking tabs 48 are located at respective opposite sides of the legs 43 and are of sufficient size and flexibility to facilitate pressing them in opposition to their bias from an off-set, and in this instance generally parallel outward locking disposition relative to the outer faces of the legs. Each of the tabs 48 is partially separated from its leg 43 as by shear-forming in such a manner that one of its side edges coincides with the adjacent side edge of the leg while its opposite edge and the locking edge 49 thereof is separated from the leg along an angular shear line 48α (FIG. 5) which runs out at one end at the adjacent side edge of the leg and runs out at its opposite end in a solder lug opening 48b in the free terminal end portion of the leg. Thereby the portion which connects the respective locking tab to its leg is somewhat narrower than the tab, facilitating resilient flexure of the tab between locking and nonlocking positions relative to the outer face of its leg, not only facilitating snap-in mounting of the connector, but enabling ready separation of the connector from the panel by pressing the locking tabs toward one another to clear the adjacent edge defining the mounting hole 42. Operation of the tabs 48 is facilitated by having the legs 43 normally slightly splayed, that is divergently related relative to one another as indicated in dash outline in FIG. 2, so that when the connector is pressed home by inserting the cam surfaces 45 into the hole 42, and pressing toward the cam surfaces on the base web 44, the legs will be caused to yield resiliently toward one another, and the locking tabs 48 will be pushed toward one another until the stop shoulders 47 make contact with the face of the panel 41 and the legs 43 bias apart due to the resilient structure of the connector, and the tabs 48 snap into locking opposition of the edges 49 to the opposite face of the panel to lock the connector in place. By reason of the normally splayed relation of the legs 43, they will tend to hug or press toward the confronting edges defining the hole 42 and thus retain the locking shoulder edges 49 efficiently in locking relation to the mounting panel.

For clamping an electrical lead wire 50 to the terminal device or connector 40, the base or web 44 serves as an electrically conductive clamping member on and across which the wire 50 or at least a terminal end portion of the wire is received. As an opposed clamping member a threaded nut 51 is provided, desirably of square form dimensioned to be received freely but substantially non-rotatably between the legs 43 and engaged threadedly on a screw shank 52 extending through a central opening 53 in the web 44 and having a slotted or otherwise driver engageable head 54 which thrustingly opposes the outer face of the base web 44. While the head 54 is adapted to clamp a spade terminal, or even a stripped terminal end of a wire to the base web 44, a preferred connection is established by inserting the wire or at least the terminal end portion thereof between the web 44 and the nut 51 with the nut backed away sufficiently to receive the wire and then operating the screw to tighten the nut clampingly toward and against the interposed wire. Lateral escape of the wire is effectively precluded by the adjacent leg 43 and the screw shank, and twisting action of the nut 51 is precluded because it is held against turning by and between the legs 43 so that the nut moves in a straight line direction toward the base web 44 to clamp the wire terminal. By upsetting the tip of the screw shank 52 as shown at 55, it is retained against being inadvertently disassembled from the nut 51. By providing the legs 43 with inwardly pressed stop lugs 57, shear-formed along stop edges and pressed inwardly, and spaced sufficiently from the web base 44 to enable efficient backing off of the nut relative to the web base, but spaced from the plane of the stop edges 49 less than the thickness of the panel 41, the nut 51 can not escape from the assembly even though for any reason the screw is completely disengaged from the nut. The stops 57 also provide a convient thrust base toward which the nut 51 may be driven when it is desired to back the screw head 54 away from the web base 44 to provide a gap receptive of a terminal such as a spade lug.

As an important feature, the present invention provides novel means enabling effecting an electrical connection with the wire 50 even though pliable insulation 58 covering the wire conductor 59, whether a single strand as shown or a multi-strand construction, remains in place about the wire conductor and is not skinned or stripped therefrom. For this purpose, the base web 44 is provided with a rigid contact ridge 60 which projects toward the clamping nut 51 and is located, preferably aligned with the screw access and normal to the planes of the legs 43 to receive the insulated wire thereacross when the wire is inserted in the normal fashion into position in the clamp between the screw shank and one of the legs. As it will be observed, the ridge 60 is located to extend between the respective legs 43 and diametrically opposite sides of the screw clearance hole 53. Thereby the wire will extend across the ridge at either side of the screw shank or two or more of the wires can be inserted in the clamp at each side of the screw shank, as preferred. As the clamping members are forced together to squeeze the insulated wire therebetween, the ridge 60 is pressed into the insulation to effect an electrical connection with the wire core conductor 59. Excessive biting of the ridge into the insulation is avoided by having the blunt ridge of radiused crown rib form and of only limited height calculated to be sufficient to make the desired contact when the clamping members have been thoroughly but not excessively tightened into gripping engagement with the insulated wire wherein the insulation is gripped by the clamping members in ample squeezed relation to hold the wire against being pulled from the clamp but without crushing the conductor core. In fact, by its indented reception in the insulation 58, the ridge 60 serves not only as means to effect electrical contact between the base web 44 and the conductor of the wire, but as anchoring means to effect the arrangement of the wire having a pull strength which is increased greatly over prior arrangements because of the gripping of the insulation and the metal conductor or the wire simultaneously.

Because of spring-back or recovery factor in the squeezed insulation 58, frictional resistance to loosening is enhanced between the threaded nut 51 and the screw shank 52 and between the head 54 and the web or a terminal engaged between the head and web.

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Formation of the rigid, blunt contact projection, insulation interlock lug ridge 60 is readily accomplished by pressing the same in the base web 44, evidenced by an indentation 61 in the outer face of the web. In one form, the ridge 60 may be about half as high as the thickness of the material of the web 44. For example, where the material of the base web 44 is about 0.025 inch in thickness, the ridge 60 may project therefrom on the order of 0.010 to 0.015 inch.

In making the sheet metal portion of the device, it is formed up from strip sheet metal stock into a blank as shown in FIG. 5, with the various elements of the structure sheared and formed, whereafter the legs 43 are bent up along parallel juncture bend lines 63 at the opposite ends of the web 44 into the desired angular relation to the web. Although the legs 43 may themselves serve as soldered lugs, they may optionally be provided either or both with a solder lug tab extension 64 at their free ends.

As will be observed, the shoulders 47 are preferably spaced a limited distance from the inside plane of the web 44 to provide a terminal-receiving gap between such plane and the adjacent plane of the panel 41 in assembly therewith.

It will be understood that variations and modifications may be effected without departing from the spirit and scope of the novel concepts of this invention.