US3049691A

US3049691A - Insulation-crushing terminal assembly

Info

Publication number: US3049691A
Application number: US800882A
Authority: US
Inventors: Donald E Cheney
Original assignee: Reliable Electric Co
Current assignee: Reliable Electric Co
Priority date: 1959-03-20
Filing date: 1959-03-20
Publication date: 1962-08-14
Anticipated expiration: 1979-08-14

Description

A g- 14, 1962 D. E. CHENEY 3,049,691

INSULATION-CRUSHING TERMINAL ASSEMBLY Filed March 20, 1959 jrzdrziar.

United States Patent Ofifice 3,049,691 Patented Aug. 14, 1962 3 049 691 INsULAnoN-cnUsHnscrERanNAL ASSEMBLY Donald E. Cheney, Wheaten, 111., assignor to Reliable Electric Company, Franklin Park, 111., an Illinois com- Pally Filed Mar. 20, 1959, Ser. No. 800,882 Claims. (Cl. 33995) This invention relates to an insulationcrushing terminal for a plastic-insulated conductor, and more particuarly to a terminal wherein pressure is applied to remove the insulation from the conductor at the terminal.

Prior terminals have been devised which rely on pressure to crush away and remove plastic insulation at the terminal. Such terminals, however, provide no control over the amount of pressure applied, with the result that there often is excess pressure. This excess pressure unduly deforms the conductor, i.e. flattens it out, with consequent loss of mechanical strength. In fact, conductors often are broken in two in connecting them to such terminals. If not broken initially, they usually are weakened so breaking occurs subsequently.

One object of the invention, therefore, is to provide a terminal for plastic-insulated conductors wherein pressure is employed to crush away or remove the insulation but wherein means are provided for limiting the amount of pressure so that no significant conductor deformation occurs.

Another object of the invention is to provide such a terminal which lends itself to use in various types of terminal devices, such as terminal attachments, terminal blocks, binding posts, etc.

Still another object of the invention is to provide such a termnial which is inexpensive to construct and which is highly efiective in use.

Other objects, advantages and details of the invention will become apparent as the description proceeds, reference being had to the accompanying drawing wherein one embodiment of the invention is shown. It will be understood that the description and drawing are illustrative only and that the scope of the invention is to be measured by the appended claims.

In the drawings:

FIG. 1 is a fragmentary elevational view, partly in section, of a terminal block showing a portion of a terminal embodying the invention;

FIG. 2 is a top view of the terminal portion shown in FIG. 1, -a dotted line conductor shown applied to the terminal portion;

FIG. 3 is a fragmentary sectional view of a terminal block showing a complete terminal embodying the invention, and

FIG. 4 is a fragmentary elevational view, partly in section, showing the terminal of FIG. 3 in operative engag ment with a plastic-insulated conductor.

Before referring to the drawing in detail, a terminal embodying the present invention comprises a first member and a second member relatively movable toward each other. The opposing surfaces of these members are generally flat and parallel to each other. The opposing surface of one of the members has at least one protuberance, the top of which lies in a plane spaced from the surface by a distance slightly less than the diameter of a conductor, exclusive of insulation, to be used with the terminal. Finally, means are provided for forcing said members toward each other with a plastic-insulated conductor therebetween until the second member engages the top of the protuberance.

When the members are thus engaged, the force applied to the conductor is large enough to crush away and remove the insulation from the conductor at the terminal and small enough to avoid significant conductor deformation and consequent loss of mechanical strength.

The protuberances, if more than one is employed, also perform the incidental function of confining the conductor and preventing it from working its way out from between the two members of the terminal.

Referring now to the drawing, the invention is shown embodied in a terminal of the binding post type mounted in a terminal block. It will be understood, however, that the invention may be embodied in various other types of terminal devices.

The numeral 5 designates a fragmentary portion of the exterior shell of a terminal block. The interior of shell 5 contains suitable filler material 6.

Referring particularly to FIGS. 3 and 4, the terminal of the invention in its broadest aspect includes a first member 19 having a generally flat surface 11. It also includes a second member 12 having a generally flat surface 13.

Members

10 and 12 are arranged so they are relatively movable toward each other, with the generally flat surfaces 11 and 13 opposing each other and in generally parallel relation.

Opposing surface 11 of first member 10 is provided with at least one unyielding protuberance 15. As best shown in FIG. 2, four such protuberances 15 are employed in the illustrated embodiment. These protuberances are so dimensioned that the tops thereof lie in and define a plane which is generally parallel to and spaced from surface 11 of member 19. As here shown, protuberances 15 are located in quadrature relation on surface 11 of member 10. The protuberances provide a positive stop means limiting the possible proximity of the opposing surfaces of the relatively

movable members

10 and 12.

The numeral 20 designates a plastic-insulated conductor of the type commonly used in the communications field at the present time. material used for insulation on conductors of this type is polyethylene or polyvinyl chloride. Such insulation material, while providing satisfactory insulation, has the characteristic of readily being crushed away from the conductor in response to the application of moderate pressure. This characteristic, of course, is taken advantage of in terminals of this character to avoid the time con-. suming step of physically removing the insulation from the conductor before connecting the conductor to the terminal. In the drawings the insulation is designated 21 and the metallic conductor itself is designated 22.

Means are provided for forcing

members

10 and 12 toward each other and into engaging relation whereby surface 13 of member 12 engages and is positioned by the tops of protuberances 15 which act as a stop means. This final relationship is shown in FIG. 4.

In the form of the invention shown, the means for forcing the two relatively

movable members

10 and 12 together comprises a threaded stem member 25 and a nut member 26. As shown, relatively movable member 10 is associated with and has a fixed relation with threaded stem member 25, and relatively movable member 12, in the form of a washer, loosely is received on stem member 25. Nut member 26 serves to force movable member 12 into engagement with the tops of protuberances 15, as best shown in FIG. 4.

As previously mentioned, the distance between surface 11 of member 10 and the plane of the tops of protuberances 15 is slightly less than the diameter of metallic conductor 22. This relationship results in a slight deformation of conductor 22, but such deformation is insignificant so far as the mechanical strength of the conductor is concerned. The resulting modest deformation is of proper amount to insure that the deforming force is adequate mechanically to hold conductor 22 in the terminal. This force, however, is more than adequate to By way of example, plasticcrush away and remove insulation 21 from conductor 22 in the regions thereof in engagement with members 11) and 12, thus providing requisite electrical connection Without requirin g manual stripping.

Portion 30 of the illustrated terminal simply serves to anchor the terminal properly in the terminal block.

It will be seen that a terminal embodying the invention is efiective to apply a highly controlled pressure to a plastic-insulated conductor connected to the terminal. This pressure is great enough to crush away and remove the plastic insulation from the conductor at the terminal and to mechanically hold the conductor in place, and it is small enough to avoid significant conductor deformation and consequent loss of mechanical strength.

From the above description it is thought that the construction and advantages of the invention will be readily apparent to those skilled in the art. Various changes in detail may be made without departing from the spirit or losing the advantages of the invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. An insulation-crushing terminal assembly comprising a plastic-insulated conductor, a first member and a second member relatively movable toward each other, the opposing surfaces of said members being generally flat and parallel to each other, a plurality of spaced unyielding protuberances on the said opposing surface of said first member, the tops of said protuberances lying in and defining a plane spaced from said surface by a distance slightly less than the diameter of said conductor exclusive of insulation, and means forcing said members toward each other with said plastic insulated conductor therebetween until said second member engages the tops of said protuberances whereby the force applied to said conductor is large enough to crush the insulation from the conductor to establish electrical connection and small enough to avoid significant conductor deformation and consequent loss of mechanical strength.

2. An insulation-crushing terminal assembly comprising a plastic-insulated conductor, a first member and a second member relatively movable toward each other, the opposing surfaces of said members being generally flat and parallel to each other, at least one unyielding protuberance on the said opposing surface of one of said members, the height of said protuberance above said 3 surface slightly less than the diameter of said conductor exclusive of insulation, and means forcing said members toward each other with said-plasticinsulated conductor therebetween until the top of the protuberance on said one member engages the opposing surface of the other member whereby the force applied to said conductor is large enough to crush the insulation from the conductor -to establish electrical connection and small enough to avoid significant conductor deformation and consequent loss of mechanical strength.

3. The combination of claim 2 wherein said opposing surface of said one member has four spaced protuberances of equal height located in quadrature relation.

4. The combination of claim 2 wherein said forcing means comprises a threaded stem member and an associated nut member, and wherein one of the relatively movable members has a fixed relation with said stern member and the other relatively movable member is a Washer on said stem member between said nut member and said one movable member.

5. An insulation-crushing terminal assembly comprising a plastic-insulated conductor, a first member and a second member relatively movable toward each other, the opposing surfaces of said members being generally fiat and parallel :toeach other, positive stop means on one of said members engageable with the other of said members limiting proximity of the relatively movable members at a spacing slightly less than the diameter of said conductor exclusive of insulation, and means forcing said members toward each other with said plastic-insulated conductor therebetween until said positive stop means becomes effective whereby the force applied to said conductor is large enough to crush the insulation from the conductor to establish electrical connection and small enough to avoid significant conductor deformation and consequent loss of mechanical strength.

References Cited in the file of this patent UNITED STATES PATENTS 1,206,376 Randall Nov. 28, 1916 1,867,918 Lofgren July 19, 1932 2,137,840 Hayes Nov. 22, 1938 2,558,851 Jacobi July 3, 1951 2,724,809 Bunch Nov. 22, 1955