AU664376B2

AU664376B2 - Empty conduit with detachable cable assembly and method of making same

Info

Publication number: AU664376B2
Application number: AU21063/92A
Authority: AU
Inventors: James A. Cole
Original assignee: Integral Corp
Current assignee: Integral Corp
Priority date: 1991-08-16
Filing date: 1992-08-17
Publication date: 1995-11-16
Anticipated expiration: 2012-08-17
Also published as: GB2258711B; ITRM920607A1; NO304810B1; GB9217343D0; FR2684247B1; IE79449B1; ES2040661R; IE922590A1; ITRM920607A0; FR2684247A1; SE9202352D0; SE504841C2; FI923659A0; ES2040661A2; AU2106392A; BE1005584A5; IT1263227B; GB2258711A; NL9201468A; CH688214A5

Description

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AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S): Integral Corporation

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ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

INVENTION TITLE: Empty conduit with detachable cable assembly and method of making same The following statement is a full description of this invention, including the best method of performing it known to me/us:-

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Field of the Invention This invention relates generally to communication cable systems, more particularly to cable conduit and cable assemblies, and even more particularly to cable conduit and cable assemblies with means for expanding cable capability.

I Background of the Invention The continuing dynamic growth in the communications industry has resulted in the ever increasing demand for additional and different types of communication cables. For example, the initial installation of telephone cables in a particular locality Iis soon overloaded, with additional cable installations required )to meet the expanding communications requirements in that locality. Furthermore, while the vast majority of present day telecommunication, video and data transmissions are over twisted pair telephone and coaxial cables, optical fiber cables are clearly becoming the future transmission media #fr the communications industry. As i consequence, it becomes imperative that existing non-optical fiber cable assembly installations incorporate assemblies which provide not only for additioner future cable installations, but also the capability of installing optical fiber transr tsion cables in the future without the need la- -2of unearthing or replacing the initial installations.

Description of the Prior Art There are existing prior art systems which have attempted to provide this expanded cable capability. For example, U.S. Patent No. 3,862,349 discloses an underground telephone cable assembly installation in which the telephone cable is disposed inside a flexible outer housing having an outside diameter sufficiently larger than the contained telephone cable so as to provide for future placement of at least one additional cable, a pull wire also being installed along side of the existing cable for this future placement. U.S. Patent No. 3,383,456 discloses a flexible conduit with the electrical conductors being provided within or adjacent the conduit wall so that additional conductors when needed may be drawn through the conduit at a later time without having to remove the conduit.

While these prior art systems in a broad sense enable expanded cable capability, they are not completely satisfactory and have a number of disadvantages associated therewith. For example, in addition to the fact that the existing cable or conductors are located inside the conduit and would thus interfere with the future placement of additional cables therein, as well as increasing the pulling resistance of the future cable installation, the overall construction and design of the prior art systems are deficient in many material respects.

It is therefore the principal object of this invention to provide a cable assembly 25 which provides for expanded cable capability for the future.

Summary of the Invention According to the present invention, there is provided a cable assembly comprising, in combination: an original cable; Sa cable conduit extending alongside said original cable, said cable conduit having 9503W,p:\operkat,inegral.r sa2 -3inner and outer walls and constituting means for receiving a communication cable installed subsequent to said original' cable; attachment means for detachably connecting said original cable to said outer wall of said cable conduit; and a pull member installed in said cable conduit for facilitating installation of the communication cabl The invention also provides a method for making a cable assembly, comprising: providing an original communication cable; providing a cable conduit alongside and paralleling said original communication cable, said cable conduit having an outer wall and having an inner wall defining a lumen passageway; detachably connecting said original co..,munication cable to said outer wall of said cable conduit; and 15 subsequently installing a second communication cable within said cable conduit by drawing said second communication cable within said lumen passageway.

:i The invention is further described by way of example only with reference to the accompanying drawings.

Brief Description of the Drawings Figure 1 is a partial perspective view of a section of the conduit and original communication cable combination in accordance with the teachings of the present invention, illustrating in phantom an optical fiber cable which will be pulled through the 25 conduit in the future; Figure 2 is a cross sectional view of the conduit and original communication cable illustrating one method of attachment of the original communication cable to the conduit; Figure 3 is a cross sectional view of the conduit and 95307,p:opce\katrjntcgI.re3.3 original communication cable illustrating a second method of attachment-of the original communication cable to the conduit; Figure 4 is a cross sectional view of the conduit and original communication cable illustrating a third method of attachment of the original communication cable to the conduit; Figure 5 is a diagrammatical view of the conduit and cable combination, illustrating the ends of the cable having been detached or stripped from the conduit surface.

The drawings are not necessarily to scale, and certain portions may have been exaggerated to emphasize certain details of the invention.

Description of the Preferrod Embodiment In the description which follows, like parts are indicated throughout the specification (and drawings) with the same respective reference numerals.

Referring initially to FIGURE 1 of the drawings, a cable conduit 12 having an outer wall 14 and an inner wall 16 is depicted. The ceble conduit 12 is of the type conventionally known in the industry and is generally formed by the extrusion of polymeric material, such as a polyethylene or polyvinyl chloride, to form an elongated, flexible duct to serve as a protective underground housing for a communication transmission cable. One such form of conduit is currently being sold by Integral Corporation of Dallas, Texas, the assigns.i of this invention, under the CABLECON trademark.

In accordance with conventional approaches, the cable conduit is buried underground with the particular transmission cable normally either already having been pre-inserted within the conduit or inserted within the conduit after the conduit is buried.

In accordance with the present invention, however, and with reference again to FIGURE 1, the transmission cable 10 is 4 attached to and in parallel with the outer wall 14 of conduit 12.

This assembly is then installed underground, and cable 10 provides the initial communication link at the time of installation. The cable 10 will therefore be hereinafter referred to as the "original cable", and under present day applications would normally be either a twisted pair or coaxial type cable. The conduit 12, being completely empty, thus serves as a raceway for the future insertion of a cable 20. Cable 20 will therefore be hereinafter referred to as the "subsequently installed cable", and in this example would be an optical fiber cable.

To facilitate the future installation of the *i subsequently installed cable, a string or pull member 18 (FIGURES 2-4) is also preinstalled in the conduit 12, paralleling the length of the conduit, for use in pulling or drawing in the cable 20 through the empty conduit. In addition, it is desirable that the inner wall 16 of the conduit be prelubricated or formed of S prelubricated material to facilitate this cable pull-through.

In accordance with a principal feature of the present invention, the original cable 10 is detachably connected to the conduit wall 14 so that the cable, when necessary, may be separated or stripped from the conduit 12 at its splicing ends as illustrated in FIGURE 5. Accordingly, three different methods or embodiments for effecting this detachable connection are respectively depicted in FIGURES 2, 3 and 4, and are now described.

Referring to FIGURE 2, the conductor cable 10 is removably attached, and held in parallel proximity, to the conduit 12 by a frangible polymer jacket 24 formed along the length of the cable-conduit assembly (as illustrated in FIGURE This jacket, preferably of a thickness not greater than .030 inches, may be coextruded at the same time as the extrusion of conduit 12, with the original cable 10 being positioned between the outer wall 14 and jacket 24 during the co-extrusion process.

5 Alternatively, and with reference to FIGURE 3, a thin frangible web 26 may be formed intermediate, and along the length of, the cable 10 and conduit surface 14, the web 26 retaining the original cable 10 to conduit 12 until it is broken to free the ends 10a from the conduit outer wall.

In the embodiment illustrated in FIGURE 4, a pair of resilient grasping extensions 28 with retention fingers 28a may be integrally formed as part of -nd at the time of the extrusion of, the conduit 12, these extensions retaining the cable 10 in parallel and proximate to the conduit wall 14. In this example, the original cable 10 will be removably connected with the conduit after the completion of the extrusion process.

The detachable connection of original cable 10 with conduit 12 enables the release of the cable, as shown in FIGURE in order to alter the direction of tiie flow of the cable and S" conduit at the splicing ends, for example. In the example shown in FIGURES 1-3, the detachment will be effected by selectively fracturing the jacket 24 or web 26; in the example shown in FIGURE 4, the cable 10 is selectively pulled free from the resilient grasp of grasping assembly 28.

While preferred embodiments of the present invention nave been shown and described herein, further modifications and improvements may be made by those skilled in the art without departing from the spirit and scope of the invention, as solely defined by the appended claims.

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Claims

1. A cable assembly comprising, in combination: an original cable; a cable conduit extending alongside said original cable, said cable conduit having inner and outer walls and constituting means for receiving a communication cable installed subsequent to said original cable; attachment means for detachably connecting said original cable to said outer wall of said cable conduit; and a pull member installed in said cable conduit for facilitating installation of the communication cable.

2. The cable assembly in accordance with claim 1, wherein the inner wall of said cable conduit is prelubricated.

3. The cable assembly in accordance with claim 1, wherein said attachment means for detachably connecting said original cable to said outer wall of said cable conduit S' comprises a frangible jacket. 20 4. The cable assembly in accordance with claim 1, wherein said attachment means for detachably connecting said original cable to said outer wall of said conduit comprises a frangible web. 9 The cable assembly in accordance with claim 1, wherein said attachment means for detachably connecting said original cable to said outer wall of said conduit comprises resilient fingers integral with said conduit.

6. The cable assembly in accordance with claim 1, wherein said cable conduit comprises means for receiving an optical fiber communication cable and wherein said original cable is a different type of cable. ,2" 1

7. A method for making a cable assembly, comprising: N 950307,p;\opctlnnlcgral.rs,7 -8- providing an original communication cable; providing a cable conduit alongside and paralleling said original communication cable, said cable conduit having an outer wall and having an inner wall defining a lumen passageway; detachably connecting said original communication cable to said outer wall of said cable conduit; installing a pull member in said cable conduit for facilitating installation of a second communication cable; and subsequently installing a second communication cable within said cable conduit by attaching the second communication to the pull member and drawing the pull member and thereby said second communication cable within said lumen passageway.

8. The method in accordance with claim 7, wherein the step of detachabiy connecting said original communication cable to said outer wall of said conduit comprises the step of providing a frangible web and connecting said web between said original communication cable and said outer wall of said conduit.

9. The method in accordance with claim 7, wherein the step of detachably connecting said original communication cable to said outer wall of said conduit o comprises the step of providing a frangible jacket and wrapping said frangible jacket circumferentially around said original communication cable and said conduit. ,10. The method in accordance with claim 7, wherein said step of detachably connecting said original communication cable to said outer wall of said conduit 25 comprises the step of providing resilient fingers on said conduit and inserting said *9 original communication cable within said resilient fingers.

11. A cable assembly substantially as hereinbefore described with reference to the drawings. 950905,q:\oper\kat,Integral.248,8 -9-

12. A method for making a cable assembly substantially as hereinbefore described with reference to the accompanying drawings. Dated this 7th day of March, 1995 INTEGRAL CORPORATION By its Patent Attorneys DAVIES COLLISON CAVE S S S S. S S S S S S S. 5* S S S S S S S 55 5 5 S S S. S S S S S* 950307,p. opctkai~inegralrcs,9 Abstract An empty conduit with a communication cable of one type detachably connected to the outer wall of the conduit enables the future installation of one or more communication cables, particularly of a different type, within the conduit. Illustrated detachable, connections include frangible surrounding jacket, frangible web and a resilient grasping extension assembly. KRG\102QO\B5592.APP 'o 0 00* S e4 ease