Connector Device For Supporting Cables And For Additionally Providing An Electrical Connection

Abstract

The present connector device provides a somewhat elongated element having an internally threaded surface and having at least one end thereof chamfered. The connector device can be further formed, or may include means, to be secured to a fixed member. In one embodiment, the elongated element has located in the end opposite from the chamfered end an insert of electrically insulating material, and in the center of this insert is disposed an electrically conducting member. The elongated member in combination with its end piece is so designed that it is self-threading on the outer jacket of a cable with which it is engaged. When employed with a coaxial cable it includes an electrically conducting threaded surface and is designed to come in electrical contact with the inner shield of the coaxial cable. In addition, in this last mentioned embodiment the present device makes further electrical contact between the center conductor of the coaxial cable and the centrally disposed conducting member of the end piece.

Description

BACKGROUND

Although the present connector is usefully employed with all forms of cable, especially miniaturized cables or cables used with miniaturized electronic equipment, the description thereof will be more meaningful if considered with a coaxial cable.

The use of coaxial cables for the purpose of transmitting signals between decision circuits of some electronic system and transducers to carry out the implementation of the decisions, is well known. One of the problems that has arisen in connection with the use of a coaxial cable is the problem of connecting, or terminating, such a cable with an electronic circuit to which the signals (that the coaxial cable is carrying) are transmitted. The connection of the coaxial cable with the electronic circuit must be by some means which can engage the coaxial cable with the electronic circuit to which it is carrying a signal so as to withstand normal physical handling, or pull apart forces, when such electronic equipment is assembled or used. For instance, in the fuel gauging system of an airplane, the signals from the probes in the fuel tank are transmitted through an intermediary electronic system to the fuel pumps over coaxial cables. The cable connectors at the probe ends, the pump ends, and the decision circuits in between must be able to withstand the vibrations of an aircraft when it is in operation, i.e., withstand the forces that would tend to pull the coaxial cables away from their respective terminal connections.

Heretofore, cable connectors used for the purposes set forth above have been shipped in a disassembled collection of pieces. The assembly of these pieces has heretofore ordinarily required special tools and experience. With such prior art connectors, the connector housing has been formed so that it could be crimped to the outer jacket and/or soldered to the inner shield of the coaxial cable. When such devices have been used with miniaturized circuits, the assembly of the connectors has required great skill, for instance, in the alignment of the center conductor of the cable with the female slot in the connector.

SUMMARY

The present invention provides a means for supporting a cable to a fixed member. Further, the present invention provides a means for connecting a cable with electronic gear which requires no special tools and the minimum amount of skill. At the same time the present device provides an electrical connection between a cable and electronic gear that can resist "pull apart" forces resulting from handling, vibrations, etc. while simultaneously (when used with a coaxial cable) providing good electrical contact between the inner shield and the portion of the connector which serves as a continuation thereof between the inner conductor of the coaxial cable and a conductor mounted in the connector.

The features and objects of the present invention will be better understood in accordance with the following description, when studied with the accompanying drawings in which:

FIG. 1 shows a connector device threaded onto a coaxial cable;

FIG. 2 shows a connector device threaded onto a coaxial cable which has a plurality of inner conducting wires;

FIG. 3 shows a coaxial cable about to be inserted into a connector device;

FIG. 4 shows the coaxial cable having been inserted into the connector of FIG. 3;

FIG. 5 shows a graphic relation between the ratio of the major diameter of the threads to the cable diameter and the pounds in pull strength.

The connector element of the present invention and in the preferred embodiment is made of an electrical conducting material such as brass, although it is obvious that other material such as copper, silver, gold, etc. can be used. It should be understood that a nonconducting threaded element could be used if no electrical connection is required, or a nonconducting threaded element on a conducting inner surface might well be employed in the present device. In the preferred embodiment, brass is used because it is sufficiently hard in a structural, or mechanical sense, that it can be self-threading with respect to the normally used plastic material that comprises the cable sheath of cables, including coaxial cables.

The dimensions of the diagrams of the figures are greatly exaggerated for the purpose of this discussion. In FIG. 1 there is shown a coaxial cable 11 comprising an outer sheath 13, an inner shield 15, an insulator coating 17 and a center conductor 19. The outer sheath 13 is usually composed of some polyethylene material or a cotton material suitably coated with plastic. The inner shield is usually composed of a woven copper-strand material, or some other suitable electrically conducting material. The inner insulator coating normally comprises a filler of a polyethylene or some other suitable electrically insulating material. The center conductor is usually composed of copper wire or a wire of some other suitable electrically conducting material. As is shown in FIG. 1, the threaded element 14 has a chamfered front end 12. The chamfered front end 12 enables the cable to be easily inserted into the connector element 14. When the connector element 14 is used with miniaturized systems the chamfered front edge is especially important. Also as shown in FIG. 1, the major diameter of the threads of connector element 14 is smaller than the diameter of the outer sheath 13. The relationship between the ratio of this major diameter to the diameter of the cable and the pull in pounds is shown in FIG. 5 as will be discussed hereinafter. It is apparent that with the major diameter being smaller than the diameter of the cable the threads squeeze the outer sheath into a threaded configuration and hence provide good retention characteristics for keeping the cable 11 from being pulled out of the connector 14. The major diameter cannot be made too short lest the plastic sheath would get cut away from the unthreaded portion of the sheath.

As can be seen in FIG. 1, there are means in the form of ears 16 and 18 (shown in phantom) formed from or added to the connector 14 for the purpose of securing the connector to some fixed member. In each of the ears 16 and 18 there are respectively shown two apertures 20 and 22. It should be apparent that the ears can be bolted or screwed onto a fixed member for securing the cable in some position whereby the electronic equipment with which it is going to be used can be simply connected up to the end of the cable. Although there are ears shown, it should be clear that other forms of securing means could be used such as an outer thread (and others) as will be described in FIGS. 3 and 4.

In FIG. 2, there is shown connector element 14 connected to a coaxial cable 11a, and all of the parts identified in the description of FIG. 1 are identical with the device shown in FIG. 2. The difference between the arrangement shown in FIG. 2 and that shown in FIG. 1 is that the coaxial cable of FIG. 2 is a cable with a plurality of inner conductors therein. The function of the connector with respect to the coaxial cable shown in FIG. 2 is identical with that described in connection with the device shown in FIG. 1 and no further explanation need be offered here.

In FIG. 3, there is shown a coaxial cable 11 with the same part makeup as the coaxial cable shown in FIG. 1. Identification numbers are the same. Further shown in FIG. 3 is a connector 21 which is designed to make an electrical connection with a coaxial cable as will be described hereinafter. The connector 21 is made up of the elongated cylindrical element 23, electrically insulating end insert 25, and centrally located conductor 27. The cylindrical element 23, as indicated earlier, in the preferred embodiment, is made of brass, although it may be made of some other suitable electrically conductive material. Also in the preferred embodiment the insulating end insert 25 is composed of DuPont Teflon, although any other suitable electrically insulating material, such as epoxy resin, with the characteristic of rigidity and further into which a member may be molded or inserted, can be used. The end insert 25 is formed to be press fitted into the end but obviously it can be secured by some means if so desired. The centrally located conducting element 27 in the preferred embodiment is made of brass, although other suitable electrically conducting materials may be used. In the preferred embodiment, brass is employed because the centrally located conductor must be sufficiently strong to cause the center conductor 19 of the coaxial cable to bend thereupon and come in good electrical contact therewith.

IN FIG. 4, the coaxial cable shown in FIG. 3 as well as the connector element shown in FIG. 3 are shown joined together in the fashion in which they are used. The identification numerals are the same as those shown in FIG. 3. It will be noted in FIG. 4, that when the cylindrical element 21 has been threaded or turned around the coaxial cable 11 there are threads not only bunching or deforming the outer sheath 13 but also coming in physical contact with the inner shield 15. It is necessary to have the minor diameter of the threads smaller than the diameter of the inner shield 15 so that the threads come in good contact with the inner shield 15 thereby providing the coaxial cable effect between the cylindrical element 23 of the connector and the combined center conductor 19 and centrally located conductor 27. In FIGS. 3 and 4, the contact between the threads and the inner shield 15 is accomplished by using a tapered thread in the connector. Such an arrangement insures that the outer sheath will not be actually cut while still providing good electrical contact with shield 15. However, a tapered thread need not necessarily be used if the major diameter is not too short and the outer sheath is pliable enough to be easily deformed without tearing.

It is necessary in the utilization of the connector device of the present invention to clean back or strip the conductor 19 of the insulation coating 17 to a sufficient length so that when the coaxial cable is threaded by the connector device, the center conductor 19 will have a sufficient contact surface to provide a good contact with the centrally located conductor 27. On the other hand, it is not desirable to strip the conductor 19 back too far. In the preferred embodiment, the contacting surface 31 of the centrally located conductor 27 is approximately 0.004 of an inch long and accordingly the center conductor 19 is stripped back approximately 0.005 of an inch. The dimensions vary with different types of cables.

In addition, the inner shield 15 should be stripped back a sufficient distance so that there is good electrical insulation, or electrical isolation, between the exposed center conductor 19 and the inner shield 15. In the preferred embodiment, the inner shield is stripped back from the edge of the insulating layer 17 approximately 0.001 to 0.005 inches, however, this distance obviously varies with different types of cable. It is apparent that the distances shown in the diagram are greatly exaggerated for the purpose of this description.

It should also be apparent from the drawing in FIG. 4 that when the coaxial cable has been inserted into the connector 21, the center conductor 19 slides up onto the contact surface 31 of the centrally located connector 27 and provides a good electrical contact between the center conductor 19 and the centrally located conductor 27. At the same time, the threaded inner surface of the cylindrical element 23 comes into physical contact with or threads with the inner shield 15 as well as the outer sheath 13. The contact between the threads of the cylindrical element 23 and the inner shield 15 provides a good electrical contact and also provides for a certain amount of resistance to a pulling or dislodging of the coaxial cable from the connector element. While the drawing shows the threads in some condition less than full physical contact, this is for illustration purposes and it should be understood that the shield conforms as does the plastic to give a good electrical contact. The main resistance to this dislodgement is effected by the threading of the outer sheath 13. The plastic material or the cotton material with suitable coating thereon is deeply deformed by the threads of connector 21 and this provides a good engagement between the cylindrical element 23 and the outer sheath 13 of the coaxial cable. Accordingly, the connector 21 cannot be readily pulled from the coaxial cable and also accordingly there is a good electrical contact and coaxial characteristic between the coaxial cable and the connector.

By way of illustration in FIG. 5, there is shown the relationship between pounds of pull in an effort to disengage the connector 21 from the coaxial cable 11 and the ratio of the major diameter md of the threads and the diameter of the cable D. It can be seen in FIG. 5 that the smaller the distance between the outer edges of the threads with respect to the diameter of the coaxial cable, the larger the pounds of pull that the assembly can withstand. Obviously, there is a limit to how small the ratio can be made since too small a ratio would result in shearing the outer shield or the coaxial cable itself. In the preferred embodiment, the ratio is greater than 7/10.

The present invention provides a number of advantages in the art of connecting coaxial cables. It is not necessary with this device to provide clamps or soldering or crimping or any of the other techniques which are necessary with other devices. It is possible to use this connector with coaxial cables of a very small type. Inasmuch as the electronic art has tended toward more and more miniaturization, it becomes apparent that this form of connector is highly desirable. In addition, the present device provides the advantage that there is no necessity for great skill in aligning the center connector with the centrally located connector. The design of the connector itself causes the center connector 19 to come in good physical electrical contact with the centrally located connector 27 without any elaborate alignment techniques necessary. It, of course, should be understood that the cable retention or the resistance to the separation of the coaxial cable from the connector depends upon the materials of the cable jacket or shield.

In addition, there is no necessity to assemble the present device to provide a connector. It is preassembled and it need only be threaded onto the cable. It follows that if there is need for it (the breaks or the like), the connector can be easily unscrewed and reused. The reuse feature of the present invention is not found in the prior art.

Claims

I claim:

1. A cable connector holding a cable comprising in combination: a cable means, a hollow elongated element having an inside surface and an outside surface and having first and second open ends; said inside surface being formed into a cutting edge threaded pattern wherein the major diameter of said threaded pattern is smaller than the outside diameter of said cable whereby when said hollow elongated member is threaded onto said cable there results a self-threading action to threadably engage said hollow elongated member with said cable, said first end of said hollow elongated member being formed in a chamfered configuration, said cable being a coaxial cable having a shield and a middle conductor and wherein there is further included an end piece of electrically insulating material formed to fit into said second open end of said hollow elongated member, and wherein there is further included an electrical conducting member disposed in said end piece and further disposed to protrude toward said first open end so that when said coaxial cable is held in said hollow elongated member said middle conductor comes in contact with said electrical conducting member, said end piece having a recess formed therein which recess is disposed to open within said hollow elongated element and toward said first end and wherein said electrical conducting member protrudes into said recess.