WO1998015864A1

WO1998015864A1 - Submarine optical cable joint with terminating sockets

Info

Publication number: WO1998015864A1
Application number: PCT/US1997/018075
Authority: WO
Inventors: Mohamad A. Amirkalali
Original assignee: Tyco Submarine Systems Ltd.
Priority date: 1996-10-10
Filing date: 1997-10-08
Publication date: 1998-04-16
Also published as: TW357473B; CA2267891A1; AU5193698A; JP2001502074A; AU735821B2; EP1012649A4; EP1012649A1

Abstract

A universal submarine fiber-optic cable joint is provided with universal terminating sockets (10) for use with unarmored fiber-optic cables (1, 2). The device includes first and second universal terminating sockets (10) for terminating the strength members (6) of a first and a second fiber-optic cable respectively. The optic fibers (19) of the two cables (1, 2) are spliced together and are stored in a fiber storage tray that is positioned between the two terminating sockets (10). A cylindrical steel casing (12) encloses the fiber storage tray and is secured to the terminating sockets (10) by pins (13). The first and second universal terminating sockets (10) of the invention are interchangeable; either socket (10) can be secured to either end of the casing (12) by one or more pins (13).

Description

SUBMARINE OPTICAL CABLE JOINT WITH TERMINATING SOCKETS

Field of the Invention

The present invention relates to the field of submarine fiber-optic communications systems and, in particular, to a device for connecting two fiber-optic cables together.

Background of the Invention

In our truly global society, more and more people are becoming interconnected with one another through telecommunications systems. Although submarine fiber-optic cable communications systems are but one type of telecommunication system, submarine fiber-optic cables are capable of carrying a greater number of data and voice transmissions than traditional submarine cable systems or modern satellite communication systems.

Stretching thousands of miles across the oceans, submarine fiber-optic cables lie on the ocean's floor, thousands of feet below sea level. Because no one cable could be made that extended thousands of miles in length, submarine fiber-optic cable communication systems are comprised of a series of submarine fiber-optic cables that are spliced together at cable joints. In this manner, many individual cables can be connected to form a single cable of the required length.

If one were to cut open a standard "unarmored" fiber-optic cable, he would see that each cable is comprised of a series of optic fibers clustered around a steel "king" wire. Together, these wires form the fiber-optic "core" of the cable. The fiber-optic core itself is surrounded by steel strength members and two watertight, insulating jackets (an inner copper jacket and an outer polyethylene jacket) encase the entire assembly. The function of the optic fibers is to carry the data and voice transmissions sent over the fiber-optic cable; the steel wires carry any loads placed upon the cable and, in conjunction with the insulating jackets, give the cable its rigidity. A cable joint is used to connect two cables together. Traditionally, cable joints were formed by "terminating" the two cables in separate terminating sockets and securely connecting the two terminating sockets with a load-bearing fiber storage tray or cylinder. The individual optic fibers of the cables were then spliced together and secured in the storage tray and the entire subassembly was covered with a steel jacket and insulated with heat-shrink insulation to make the cable joint waterproof. An alternate cable joint design replaces the load-bearing fiber storage tray or cylinder with a "floating" (i.e., non-load-bearing) fiber storage tray. In this design, because the fiber storage tray is not securely connected to the terminating sockets, all loads placed on the individual cables are carried across the steel casing rather than through the storage tray. Cable terminating technology is well-known in the prior art. The idea behind cable terminating is to secure the load-bearing steel members of the fiber optic cable, including both the steel strength members and the steel king wire, to a terminating socket so that any load placed on the steel members would be transferred to the terminating socket. The fragile optic fibers of the cable, however, would completely pass through the terminating socket.

Typically one terminates a fiber-optic cable by stripping off the cable's insulating jackets, separating the steel strength members from the fiber-optic core, and slipping both the strength members and the core through the center of the terminating socket. A copper jacket and a steel plug are then placed over the core and the steel plug is firmly wedged into the terminating socket. In this way, the steel strength members are secured against the interior surface of the terminating socket, while the fiber-optic core passes freely through the socket. To terminate the steel king wire, one merely needs to separate the individual optic fibers from the king wire and to attach the king wire to a king wire clamp assembly. Because the king wire clamp assembly is also connected to the terminating socket, or is connected to a load-bearing fiber storage tray that is itself attached to the terminating socket, the end result is that all load-bearing steel members of the fiber-optic cable are secured to the terminating socket.

In a typical cable joint, the two cables to be joined are connected to terminating sockets (hereinafter the "first" and "second" terminating sockets) that differ in design from one another. The reason the two terminating sockets are not identical is because the means for securing the first terminating socket to the steel casing and/or to the fiber storage tray usually differs from the means for securing the second terminating socket to the steel casing and/or to the fiber storage tray. Therefore, as a result, the cable joint has an "A" end and a "B" end; only "A" -type terminating sockets can connect to the "A" end of the cable joint and only "B"-type terminating sockets can connect to the "B" end of the cable joint.

For example, in some designs the first terminating socket is "connected" to one end (the "A" end) of a cylindrical steel casing by compressive force. To accomplish this, one first runs the cable longitudinally through the casing and then attaches the cable to the first terminating socket. Next, the cable and attached terminating socket are pulled back through the casing until the shoulder of the socket makes contact with the end plate of the casing. The second terminating socket, on the other hand, is connected to the casing at its other end (the "B" end) by mechanical means. This terminating socket, which is already connected to the first terminating socket by a fiber storage tray, is connected to the casing by a threaded assembly, locking rings, or some other mechanical device. As a result, the compressive force created by securing the second terminating socket to the steel casing forces the shoulder of the first terminating socket up against the end plate of the steel casing and holds it firmly in place. Thus, although both terminating sockets were attached to the storage tray in the same manner, the means by which they were attached to the steel casing differ greatly, thereby requiring differing "A" and "B" terminating socket designs.

The disadvantage of this configuration is that it complicates the laying and repairing of submarine fiber-optic cables. Because every section of cable has an "A" end and a "B" end (i.e., one end of the cable is terminated with an "A"-type socket and the other end is terminated with a "B"-type socket), workers laying or repairing submarine cables must always be aware of which end of the cable they are working on because an "A" end can only connect to a "B" end with conventional cable joints. Routinely, however, a cable-laying ship will arrive at its destination only to find that while the "B" end of its spooled cable is ready to be laid out, the end of the cable to which they wish to connect is also a "B" end. In such a situation, workers must either replace the terminating socket of the spooled cable (turning a "B" end into an "A" end), or make an imperfect "B-to-B" (or "A-to-A") connection.

Summary of the Invention In light of the above, it is an object of the present invention to provide a universal submarine fiber-optic cable joint with universal terminating sockets for use with fiber-optic cables. In particular, this invention is designed to be used with unarmored fiber-optic cables, although it may readily be adapted for use with armored cables as well. It is a further object of the present invention to provide a submarine fiber-optic cable joint wherein either end of the cable joint casing can connect to a fiber-optic cable that has been terminated in a universal terminating socket.

It is an additional object of the present invention to provide a submarine fiberoptic cable joint wherein either end of the cable joint casing can connect to a fiber-optic cable that has been terminated in a terminating socket that has a connection interface that is substantially similar to the connection interface of the universal terminating socket.

Accordingly, it is an embodiment of the invention to provide a universal submarine fiber-optic cable joint with universal terminating sockets. The device includes first and second universal terminating sockets for terminating the strength members of a first and second fiber-optic cable respectively. The optic fibers of the two cables are spliced together and are stored in a fiber storage tray that is positioned between the two terminating sockets. A cylindrical steel casing encloses the fiber storage tray and extends over a portion of the first and second terminating sockets. The first terminating socket is secured to the casing by pins that extend through apertures in the casing and are secured in pin chambers in the first terminating socket. A second set of pins secure the second terminating socket to the casing by passing through a second set of apertures in the casing and engaging pin chambers in the second terminating socket.

The first and second universal terminating sockets of the invention are interchangeable; either socket can be secured to either end of the casing by one or more pins. It is this feature of the terminating sockets that make them "universal." Although in the preferred embodiment of the invention the two terminating sockets are identical, for the terminating sockets to be interchangeable, it is only necessary that their connection interfaces be substantially similar. Likewise, either end of the casing can be secured by one or more pins to any terminating socket that has a connection interface that is substantially similar to the connection interface of the universal terminating socket. This feature of the casing make it "universal" as well.

Additional objects, advantages, embodiments, and novel features of the invention will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention.

Brief Description of the Drawings

The invention will be more readily understood through the following detailed description, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of the preferred embodiment of the invention; FIG. 2 is the perspective view illustrated in Fig. 1 with the snap rivets and pins removed, and with portions of the interior structure illustrated by dashed lines;

FIG. 3 is an expanded perspective view of the components used in a universal terminating socket for terminating a fiber-optic cable; FIG. 4 is a perspective view of a universal terminating socket; and

FIG. 5 is a perspective view of the fiber storage tray.

In Fig. 2, the portion of the invention relating to the fiber storage tray is illustrated with dashed lines. The dashed lines are used solely to show the general position of the fiber storage tray within the casing and is not intended to illustrate how the storage tray is connected to any other component. The fiber storage tray is shown in detail in Fig. 5.

Description of the Preferred Embodiment The present invention is a universal submarine fiber-optic cable joint with universal terminating sockets for use with fiber-optic cables. Although the present invention may be used with both armored and unarmored cables, the preferred embodiment of the invention is for use with unarmored submarine fiber-optic cables. As seen in Fig. 1, the present invention will be described in connection with unarmored submarine fiber-optic cables 1 and 2. In the preferred embodiment of the invention, the submarine fiber-optic cable joint is used to connect two 24-fiber fiberoptic cables for use in trans-oceanic cable operations. Before a cable is connected to the present invention, however, it is preferable that the insulating copper and polyethylene jackets 3 be stripped off, thereby revealing the cable's fiber-optic core 4 (including a steel king wire 5 and steel strength members 6. Each stripped cable 7 is then passed through an anti-extrusion washer 8 and is inserted into the cable entrance 9 of a terminating socket 10.

The universal terminating sockets 10 are partially encased by a cylindrical steel casing 12, as illustrated in Fig. 2. Each terminating socket 10 is secured to the casing 12 by three steel pins 13. The thickness of the casing 12 must be sufficient to withstand the hydrostatic pressure it is exposed to when it is on the ocean floor, and to resist any loads placed on it by the terminating sockets 10 through the pins 13.

The pins 13 connect the casing 12 to the universal terminating sockets 10 by passing through pin apertures 14 in the casing 12 and engaging cylindrical pin chambers 15 in the terminating sockets 10. The depth of the pin chambers 15 is designed to engage a sufficient volume of pins 13 to allow the pins 13 to restrain the terminating sockets 10 when any loads are placed on the terminating sockets 10. The pin chambers 15, however, must not be made too deep; if there is insufficient structure beneath the pin chambers 15, the hydrostatic pressure exerted on the pins 13 might push them through the floor of the pin chambers 15 and into the terminating chamber 16 of the terminating sockets 10.

Once the pins 13 have been inserted into the casing 12 and the terminating sockets 10, it is desirable that they stay there. Therefore, to ensure that the pins 13 will not fall out once they have been inserted, it is preferable that the pins 13 be knurled, although a threaded access hole 17 should be provided to facilitate later pin removal. Because the length of a pin 13 is less than the combined depth of a pin aperture 14 and a pin chamber 15, snap rivets 18 are used to cover the pins 13 and to make the snap rivet/pin assembly lie flush with the outer surface of the casing 12. In the preferred embodiment of the invention, each pin aperture 14 and pin chamber 15 is spaced 120 degrees apart from the next pin aperture 14 or pin chamber

15. Furthermore, it is desirable that the pin apertures 14 on each end of the casing 12 be longitudinally aligned along the length of the casing 12.

The steel strength members 6 of the stripped cables 7 are secured to the terminating sockets 10 along the surface of the terminating chamber 16 of each terminating socket 10. The components used in conjunction with a universal terminating socket 10 for terminating a stripped fiber-optic cable 7 are shown in Fig. 3. In Fig. 3, however, the cable 7 has not yet been secured to the surface of the terminating chamber

16. Likewise, Fig. 4 is a detailed perspective view of a terminating socket 10 before the cable 7 has been secured. Cable terminating technology, however, is well-known in the prior art.

The idea behind cable terminating is to secure the load-bearing steel members of a stripped fiber optic cable 7, including both its steel strength members 6 and its steel king wire 5, to a terminating socket 10 so that any load placed on the steel members is transferred to the terminating socket 10. The fragile optic fibers 19, however, completely pass through the terminating socket 10.

With reference to Figs. 3 and 4, one typically terminates a fiber-optic cable 1 or 2 by stripping off the cable's insulating jackets 3, separating the steel strength members 6 from the fiber-optic core 4, and slipping both the strength members 6 and the core 4 through the center of the terminating socket 10. A copper jacket 20 and a steel plug 21 are then placed over the core 4 and the steel plug 21 is firmed wedged into the terminating chamber 16. In this way, the steel strength members 6 are secured against the surface of the terminating chamber 16, while the fiber-optic core 4 passes freely through the socket 10, the copper jacket 20, and the steel plug 21. To terminate the steel king wire 5, one merely needs to separate the individual optic fibers 19 from the king wire 5, pass the optic fibers 19 through a king wire clamp assembly 22, and attach the king wire 5 to the king wire clamp assembly 22. Because the king wire clamp assembly 22 is also connected to the terminating socket 10 by screws (not shown) the end result of this process is that all load-bearing steel members of the fiber-optic cable 1 or 2 are secured to the terminating socket 10.

After the fiber-optic cables 1 and 2 have been terminated in terminating sockets 10, the individual optic fibers 19 of each cable 1 and 2 are connected in the desired combination. Methods of splicing optic fibers 19 together (such as recoating or mechanical splinting) are well known in the prior art. The spliced optic fibers (not shown) are then stored in a fiber storage tray 23. As shown in Fig. 2, the fiber storage tray 23 is positioned between the terminating sockets 10 and is completely enclosed within the casing 12. The fiber storage tray 23 may be firmly connected to the king wire clamp assemblies 22 and/or the terminating sockets 10 (a "load-bearing fiber storage tray"), or it may loosely connected to the king wire clamp assemblies 22 and/or the terminating sockets 10 (a "floating fiber storage tray"). In the preferred embodiment of the invention, the fiber storage tray 23 is loosely connected to the king wire clamp assemblies 22.

Although a fiber storage tray 23 is used in conjunction with this invention, alternate embodiments of the invention may include using fiber storage cylinders or "loose-fit" storage means for storing the spliced optic fibers (not shown). Likewise, the cylindrical nature of the casing 12 is not an essential feature of this device. The cylindrical nature of the casing 12, however, is preferable because it makes application of heat-shrink insulation (not shown) over the casing 12 easier.

In the preferred embodiment of the invention, the terminating sockets 10, the pins 13, and the casing 12 are all made out of high-strength steel. However, because the fiber storage tray 23 is not a load-bearing component in the preferred embodiment of the invention, this component is preferably made out of aluminum, although it can be made out of molded plastic as well.

The submarine fiber-optic cable joint that is the subject of the present invention has been designed to operate in conjunction with the disclosed universal terminating sockets 10. A unique feature of the invention, however, is that the connection interface of the casing 12 (i.e., the location of pin apertures 14) is designed to operate with any terminating socket (a "third-party terminating socket") whose connection interface (i.e., the location of pin chambers 15) is similar to the connection interface of a universal terminating socket 10. The similarity between the connection interfaces of the third- party terminating socket and the universal terminating socket 10 need not be exact; the only requirement is that the third-party device have one or more pin chamber 15 that matches up with a pin aperture 14 in the casing 12. If such a match can be found, then the casing 12 can be connected to the third-party terminating socket by one or more pins 13.

This "universal" feature of the casing 12 ensures that either end of the casing 12 can be connected to any terminating socket that has a connection interface similar to that of a universal terminating socket 10. Furthermore, as is readily apparent by the figures and the above disclosure, each terminating socket 10 of the present invention is likewise "universal" because it can be connected to either end of the casing 12. Because of the interchangeableness of terminating sockets 10 (or of any terminating sockets that have substantially similar connection interfaces), the present invention is not subject to the "A-B" connection problems detailed earlier. Thus, the disclosed universal submarine fiber-optic cable joint is easier to use and is more versatile than currently-existing cable joints that require dissimilar "A" and "B" terminating sockets.

Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the above-recited detailed description, wherein only the preferred embodiment of the invention has been shown and described. The description of the preferred embodiment is simply by way of illustration of the best mode contemplated for carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modification in various respects, all without departing from the invention. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive.

Claims

I claim:

1. A fiber-optic cable joint for connecting fiber-optic cables, comprising: a. a first terminating socket for terminating a substantial number of the strength members of a first fiber-optic cable, said first terminating socket defining a first pin chamber; b. a second terminating socket for terminating a substantial number of the strength members of a second fiber-optic cable; said second terminating socket defining a second pin chamber; c. a fiber storage tray, positioned between said first terminating socket and said second terminating socket, wherein optic fibers of said first fiberoptic cable are connected to optic fibers of said second fiber-optic cable; d. a casing, having a first end and a second end, for enclosing said fiber storage tray, said casing defining a first pin aperture proximate said first end and a second pin aperture proximate said second end; e. a first pin for connecting said casing to said first terminating socket, a portion of said first pin passing through said first pin aperture and engaging said first pin chamber; and f. a second pin for connecting said casing to said second terminating socket, a portion of said second pin passing through said second pin aperture and engaging said second pin chamber.

2. The device as recited in claim 1, wherein said first terminating socket and said second terminating socket are interchangeable.

3. The device as recited in claim 1, further comprising: a. a connection interface of said first terminating socket; b. a connection interface of said second terminating socket; and c. wherein said connection interface of said first terminating socket is substantially identical to said connection interface of said second terminating socket.

4. The device as recited in claim 1 , wherein said first terminating socket and said second terminating socket are substantially identical.

5. A fiber-optic cable joint for connecting fiber-optic cables, comprising: a. a first terminating socket for terminating a substantial number of the strength members of a first fiber-optic cable; b. a second terminating socket for terminating a substantial number of the strength members of a second fiber-optic cable; c. a fiber storage tray in secure connection with said first terminating socket and said second terminating socket, wherein optic fibers of said first fiber-optic cable are connected to optic fibers of said second fiber-optic cable; d. a casing, having a first end and a second end, for enclosing said fiber storage tray; e. a first fastener for connecting said first end of said casing to said first terminating socket; f. a second fastener for connecting said second end of said casing to said second terminating socket; and g. wherein said first terminating socket and said second terminating socket are interchangeable.

6. The device as recited in claim 5, further comprising: a. a connection interface of said first terminating socket; b. a connection interface of said second terminating socket; and c. wherein said connection interface of said first terminating socket is substantially identical to said connection interface of said second terminating socket.

7. The device as recited in claim 5, wherein said first terminating socket and said second terminating socket are substantially identical.