Modular element for a solderless expandable terminal strip

[57] ABSTRACT

A modular element for use in a solderless expandable terminal strip molded from non-conductive material and formed with interlocking tenons and mortises. Each module has a screw seated in a well into which other conductor seating wells converge at an acute angle such that the screw crest assembled in the well cuts through the conductor insulation and into the conductor itself thereby making a firm anchorage as well as multiple electrical contacts therewith.

Claims, 5 Drawing Figures

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PATENTED NOV 5 1073

3,771,104

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3,771,104

MODULAR ELEMENT FOR A SOLDERLESS EXPANDABLE TERMINAL STRIP

This invention relates to conductor terminal strips, and more particularly to a novel, readily expandable strip formed of individual modular elements each including a solderless anchorage to one or more electrical conductors.

Many proposals have been made heretofore for terminal strips for anchoring two or more conductors together in a positive and reliable manner. These propos- 1 als vary widely in their suitability and practicality for this purpose. Although some of these proposals make provision for expanding the strip capacity, the strips provided for this purpose are subject to various shortcomings and disadvantages avoided by the present in- 1 vention.

The expandable solderless terminal strip provided by this invention comprises a one-piece modular element having provision for making a solderless connection with two or more conductors with or without an insula- tive covering. Each module is molded in one piece from non-conductive material and has a single threaded central well for a conductive screw the crest of the threads of which extends into a plurality of conductor seating wells having their inner ends converging through the sidewall of the central well. Hence, tightening of the single screw cuts through the insulative covering for any or all of the conductors and penetrates into the conductor itself at a plurality of points providing not only a high strength mechanical connection with the conductors but a highly effective electrical connection therebetween. It is unnecessary to remove the insulation from the conductors which are simply cut to length and inserted into the seating well followed by tightening of the anchor screw.

The exterior surfaces of the module include at least one tenon member and one complementally shaped mortise slot mateable with the corresponding tenon of another identical modular element. By this means the strip can be expanded to meet any existing or future requirements as the need arises. A further feature is the fact that the anchor screws of selected ones of the modules can be interconnected by a connector conductor with the result that any number of conductors can be connected together by using two or more modular elements having their respective screws connected in series. The screw seating well has parallel sidewalls and its outer end flares to seat the similarly flaring outer end of the screw thereby providing a stop limiting tightening of the screw.

Accordingly, it is a primary object of the present invention to provide an improved and unique modular solderless conductor terminal member for connecting a plurality of insulated or non-insulated conductors together.

Another object of the invention is the provision of an improved modular terminal element for conductors with provision for separably interlocking the same with one or more additional modules to provide a readily expandable terminal strip.

Another object of the invention is the provision of solderless conductor terminal module having a nonconductive main body formed with a threaded central well and a plurality of conductor seating wells converging and intersecting the sidewall of the central well at its inner end and adapted to be interconnected by a conductive screw threaded into the central well.

Another object of the invention is the provision of an expandable terminal·strip formed of modular elements and having provision for connecting any desired number of conductors together without limit.

These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawing to which they relate.

Referring now to the drawing in which a preferred embodiment of the invention is illustrated:

FIG. 1 is a perspective view of an illustrative embodiment of several of the invention modules joined together with conductors anchored to some of them;

FIG. 2 is a top plan view of one of the modules;

FIG. 3 is a side elevational view of the module shown in FIG. 2 and indicating by dot and dash line the manner of assembling a second module thereto, portions of the first module being broken away to show constructional details;

FIG. 4 is a cross sectional view taken along the broken line 4—4 on FIG. 2; and

FIG. 5 is a cross sectional view taken along the line 5—5 on FIG. 1.

Referring initially more particularly to FIGS. 1 and 5, there is shown several of the invention modular elements 10,10 interlocked with one another. Each module comprises a cubicle block of high strength plastic material molded in the configuration shown and having deep recesses 11,11 opening through the opposed faces thereof and provided with openings 12 at their lower ends to receive anchoring screws to secure the module to a suitable support. The two faces of the module to either side of recesses 11, 11 include a dovetail shape tenon 13 and a complementally shaped mortise 14 contoured to have a close sliding fit with the similarly contoured tenons and mortises of other modules. Although the tenons and mortises 13,14 are here shown as dovetail shape it will be understood that other interlocking contours are equally suitable and may be used.

Each module includes at least one deep threaded well 16 opening through one end surface of the module and having parallel sidewalls. Each well 16 has a coarse thread 18 here shown as of square cross section. This thread mates with a thread 19 of a metallic screw 20. Desirably the screw thread is of V-shape in cross section with its outer face lying substantially normal to the axis of the screw and its other face inclined to the screw axis. The sharp hardened crest 22 of thread 19 is effective to cut through conductor insulation as well as to ¹ penetrate into even hardened conductor wires without becoming dull or blunted.

Surrounding well 16 are a plurality of smaller diameter wells 25 converging downwardly toward the lower end of central well 16 and opening into the sides of the ’ central well near its inner end. Wells 25 are formed with precision and their inner ends are so positioned that the crest 22 of the screw thread 19 cuts into the conductor at several points along its length. Usually but not necessarily the wells 25 are designed to receive insulated conductors having either a single or multiple conductors 27 surrounded with insulation 28. Usually insulation is present and in this case it is important that the lower ends of wells 25 be so arranged that the screw crest 22 cuts through the insulation and then penetrates for a substantial distance into the conductor itself. If insulation is not to be present on the conductors then, of course, the wells are so positioned and proportioned

3,771,104 that the screw crest cuts similarly into the conductor as the screw is fully tightened.

The fully tightened condition of the screw is preferably determined by providing its outer end with an outwardly flaring surface 30 which seats in a complementally shaped countersunk outer end portion of well 16. The bottoming of taper surface 30 against this countersink definitely limits the tightening of the screw and provides the operator with an indication that the screw has been fully tightened with the crest of its thread cutting into the conductor at a number of points providing both a positive electrical connection and a firm mechanical anchorage of the conductor in the module.

FIG. 1 shows several conductors completely assembled and anchored in place by the conductive screw 20. This view also shows a connector conductor 35 having its opposite ends extending into a well 25 of adjacent modules 10,10. When so installed the two adjacent modules 10 can be employed to electrically interconnect a total of six conductors. If additional capacity for anchoring more conductors to one another is required then additional connector loops 35 are employed to interconnect additional ones of the module, or, alternatively, the modules include a larger number of wells 25. As will be appreciated, loops 35 may be used to interconnect modules widely spaced from one another simply by increasing the length of the connector loop 35.

Although modules 10 are here shown as having their interfitting tenons and mortises positioned on diametrically opposed faces of the module, it will be readily apparent that these interlocking components may be provided on adjacent faces if so desired in order that the terminal strip can be located in a corner of a compartment or about an outside comer of some piece of equipment if this should prove desirable for any reason.

While the particular modular element for a solderless expandable terminal strip herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiment of the invention and that no limitations are intended to the detail of construction or design herein shown other than as defined in the appended claims.