Hybrid cable for distributed power connectivity

A hybrid cable includes a central strength member, residing in a center of the cable. At least two insulated conductors are abutting the central strength member. One or more buffer tubes are included in the cable, each with at least one optical fiber. One or more filler rods are optionally included in the cable. A shielding layer and jacket surround the elements. In one embodiment, four large insulated conductors and two filler rods abut the central strength member. A first water-blocking tape surrounds the four large insulated conductors, filler rods and central strength member to form an inner core. A concentric core surrounds the central core. The concentric core includes two insulated conductors, plural buffer tubes and a second water-blocking tape surrounding the two insulated conductors and the plural buffer tubes. The shielding layer surrounds the concentric core, and the jacket surrounds the shielding layer. A toning signal carrying medium may also exist outside of the shielding layer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hybrid cable for both power and communication transmission. More particularly, the present invention relates to a hybrid cable possessing multiple power conductors and plural buffer tubes with multiple optical fibers in each buffer tube.

2. Description of the Related Art

Electronic devices for facilitating data, video and/or voice communications are often located in outside environments. For example, cellular systems, wifi systems, security systems and/or other networked devices are often mounted to power poles, street lights, buildings and/or cell towers. Such devices need to have access to both a power source and a central communications server. Many electronic devices are currently using optical fibers to transmit and receive communication signals with the central communications server.

When connecting power and communication channels to the electronic device, it is often required that the cabling extend up towers, poles, building walls, etc. Many operators are installing a fiber optic cable up to the electronic device and also installing a power cable up to the same electronic device. Installation costs and tower rent agreements are often based upon a per-cable charge or a per-foot of cable charge. Therefore, the use of a hybrid cable, which possesses both power conductors and optical fibers is known and desired in the art to reduce the installation costs, and any rent cost once the cable is installed. Similar per-foot and/or per-cable charges are common with the underground installation of cables, e.g., cables used in a direct burial or within an underground conduit.

SUMMARY OF THE INVENTION

The Applicant has appreciated a new internal geometry and layout of components of a hybrid cable, which improves the roundness of the cable and hence improves the storage, transportation and the installation costs and procedures.

The Applicant has also appreciated a hybrid cable design which is well suited to feed multiple electronic devices in a daisy-chain fashion. By the present design, the power needs of multiple electronic devices, e.g., five, seven, ten or more electronic devices, may be served in serial fashion by the power carried by the larger power conductors, e.g., twelve American Wire Gauge (AWG) conductors, of the hybrid cable. Also, the hybrid cable includes numerous optical fibers, e.g., up to 144 optic fibers in up to twelve buffer tubes, to serve the communication needs of the multiple electronic devices.

The Applicant has also appreciated that damage may occur to a hybrid cable, which extends over such a long distance to serve the needs of multiple electronic devices. The hybrid cable might extend up seven or more towers or poles and be buried underground between such towers and poles, either by direct burial or within a conduit. Hence, the hybrid cable would be exposed to many factors which could damage it. To this end two additional, smaller gauge conductors, e.g., eighteen AWG conductors, may be integrated into the core of the cable and be utilized by detection circuitry to alert the central communications server if the hybrid cable has been damaged. The central server can exercise alerts or device controls whenever the smaller gauge conductors indicate damage. In one embodiment, the smaller gauge conductors are placed in a concentric core which encircles a central core, possessing the larger conductors. Hence, the smaller gauge conductors are more likely to be damaged prior to damage to the larger conductors.

One or more of the drawbacks of the background art and the objectives of the present invention are addressed by a hybrid cable which includes a central strength member, residing in a center of the cable. At least two insulated conductors are abutting the central strength member. One or more buffer tubes are included in the cable, each with at least one optical fiber. One or more filler rods are optionally included in the cable. A shielding layer and jacket surround the elements. In one embodiment, four large insulated conductors and two filler rods abut the central strength member. A first water-blocking tape surrounds the four large insulated conductors, filler rods and central strength member to form an inner core. A concentric core surrounds the central core. The concentric core includes two insulated conductors, plural buffer tubes and a second water-blocking tape surrounding the two insulated conductors and the plural buffer tubes. The shielding layer surrounds the concentric core, and the jacket surrounds the shielding layer. A toning signal carrying medium may also exist outside of the shielding layer.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Like numbers refer to like elements throughout. In the figures, the thickness of certain lines, layers, components, elements or features may be exaggerated for clarity. Broken lines illustrate optional features or operations unless specified otherwise.

FIG.1is a front perspective view of a hybrid cable11in accordance with a first embodiment of the present invention.FIG.2is a cross sectional view taken along line II-II inFIG.1. The hybrid cable11includes an inner core13. The inner core13includes four large insulated conductors15,17,19and21. A central strength member23resides in a center of the inner core13. The central strength member23is flanked by a plurality of first filler rods, e.g., on two sides by first filler rods25and27. A first water-blocking tape29surrounds the four large insulated conductors15,17,19and21, the central strength member23and the plurality of first filler rods25and27to form the inner core13.

In a preferred embodiment, the four large insulated conductors15,17,19and21are each formed by a twelve American Wire Gauge (AWG) conductor, such as a stranded copper wire, which is in turn surrounded by a dielectric insulation layer. The four large insulated conductors15,17,19and21are each in abutment with the central strength member23. The central strength member23may be formed as a glass reinforced plastic (GRP) rod. The first filler rods25and27may be formed of a dielectric plastic. The central strength member23, due to its embedded fiberglass segments, provides a high degree of strength to the hybrid cable11. The first filler rods25and27do not provide much added strength to the hybrid cable11but primarily assist in keeping the overall outer cross sectional shape of the hybrid cable11circular, so that the cable can be stored and transported on a reel and deployed in the field more easily.

A concentric core31surrounds the central core13. The concentric core31includes two small insulated conductors33and35. In a preferred embodiment, the two small insulated conductors33and35are each formed by an eighteen AWG conductor, such as a stranded copper wire, which is in turn surrounded by a dielectric layer.

The concentric core31also includes a plurality of buffer tubes37,39,41,43,45,47,49,51,53,55,57and59, formed in a circle with the two small insulated conductors33and35to surround the central core13. Each buffer tube37,39,41,43,45,47,49,51,53,55,57and59includes at least one optical fiber, such as four, six, eight, ten or twelve optical fibers, preferably surrounded by a gel, such as a water blocking gel, within the buffer tube.FIGS.1-2illustrate twelve optical fibers loosely contained within each of the twelve buffer tubes, making a total of 144 optical fibers in the hybrid cable11. However, it would be possible to replace one or more of the buffer tubes37,39,41,43,45,47,49,51,53,55,57and59with a filler rod, such as a dielectric member of a same diameter as the replaced buffer tube, to reduce the fiber count of the hybrid cable11. For example, the hybrid cable11may include only eleven buffer tubes37,39,41,43,45,47,49,51,53,55and57, each with twelve optical fibers, making a fiber count of the hybrid cable11one hundred thirty two fibers.

A second water-blocking tape61surrounds the two small insulated conductors33and35and the plurality of buffer tubes37,39,41,43,45,47,49,51,53,55,57and59to form the concentric core31. A shielding layer63surrounds the concentric core31. In the illustrated embodiments of the present application, the shielding layer31is formed by corrugated aluminum. However, other materials may be used to form the shielding layer31.

A jacket65surrounds the shielding layer63. The jacket65may include one or more stripes65A of a contrasting color, to help identify the cable. For example, the majority of the jacket65may be black and the one or more stripes65A may be red. A first plurality of textile strength elements67is located between the second water-blocking tape61and the shielding layer63. In one embodiment, the first plurality of textile strength elements67includes ten bundles of fibers, e.g.,67A—67J, each of which extends longitudinally along the length of the hybrid cable11.

A second plurality of textile strength elements69is located between the first water-blocking tape29and the four large insulated conductors15,17,19and21, the central strength member23and the plurality of first filler rods25and27. In the embodiment ofFIGS.1and2, the second plurality of textile strength elements69includes a first grouping69A and a third grouping69C of textile strength elements helically wrapped around the four large insulated conductors15,17,19and21, the central strength member23and the plurality of first filler rods25and27in a first wrapping direction. The second plurality of textile strength elements69also includes a second grouping69B and a fourth grouping69D of textile strength elements helically wrapped around the four large insulated conductors15,17,19and21, the central strength member23and the plurality of first filler rods25and27in a second wrapping direction, opposite to the first wrapping direction.

The first and third groupings69A and69C of textile strength elements cross over the second and fourth groupings69B and69D of textile strength elements to hold the four large insulated conductors15,17,19and21, the central strength member23and the plurality of first filler rods25and27together during assembly of the hybrid cable11, so that the first water-blocking tape29may be wrapped there around to form the central core13.

A third plurality of textile strength elements71is located between the second water-blocking tape61and the two small insulated conductors33and35and the plurality of buffer tubes37,39,41,43,45,47,49,51,53,55,57and59. In the embodiment ofFIGS.1and2, the third plurality of textile strength elements71includes a fifth grouping71A and a seventh grouping71C of textile strength elements helically wrapped around the two small insulated conductors33and35and the plurality of buffer tubes37,39,41,43,45,47,49,51,53,55,57and59in a first wrapping direction. The third plurality of textile strength elements71also includes a sixth grouping71B and an eighth grouping71D of textile strength elements helically wrapped around the two small insulated conductors33and35and the plurality of buffer tubes37,39,41,43,45,47,49,51,53,55,57and59in a second wrapping direction, opposite to the first wrapping direction.

The fifth and seventh groupings71A and71C of textile strength elements cross over the sixth and eighth groupings71B and71D of textile strength elements to hold the two small insulated conductors33and35and the plurality of buffer tubes37,39,41,43,45,47,49,51,53,55,57and59together during assembly of the cable, so that the second water-blocking tape61may be wrapped there around to form the concentric core31.

In a preferred embodiment, the first, second and third pluralities of textile strength elements67,69and71are formed of flaccid threads, like aramid fibers, sold under the trademark KELVAR. In a preferred embodiment, the hybrid cable11may also include first and second ripcords73and75located between the second water-blocking tape61and the shielding layer63. The first and second ripcords73and75assist in opening up an end of the hybrid cable11for a termination to connectors and may also be formed of flaccid threads, like aramid threads, sold under the trademark KELVAR.

In the embodiment ofFIGS.1and2, the plurality of first filler rods25and27consists of two total filler rods. Each of the two total filler rods25and27is approximately equal in diameter to the central strength member23and also approximately equal in diameter to one of the four larger insulated conductors15,17,19and21. Also, each of the two total filler rods25and27is in abutment with the central strength member23.

FIG.3is a cross sectional view similar toFIG.2of a hybrid cable11′. The hybrid cable11′ is an alternative to the hybrid cable11. InFIG.3, the plurality of first filler rods consists of eight total filler rods25,27,77,79,81,83,85and87. The eight total first filler rods include the two larger filler rods25and27, each in abutment with the central strength member23, as described in conjunction withFIG.2. Also, the eight total first filler rods include six smaller first filler rods77,79,81,83,85and87, which are not in abutment with the central strength member23, but which do abut the inside surface of the first water-blocking tape29.

The six smaller first filler rods77,79,81,83,85and87cause the inner core13to assume a very circular outer profile, which would commonly be seen as necessary to accomplish a circular outer profile to the cross section of the overall hybrid cable11′. However, surprisingly, the Applicant has discovered that if the six smaller first filler rods77,79,81,83,85and87are omitted, the outer profile of the cross section of the overall hybrid cable11can still be made circular. Therefore, the embodiment shown inFIGS.1and2is preferred over the alternative, depicted inFIG.3, as the hybrid cable11remains circular in its outer profile while sparing the costs, added weight and assembly steps associated with the six smaller first filler rods77,79,81,83,85and87.

FIG.3also illustrates the replacement of buffer tube55with a second filler rod91, such as a dielectric member formed as a cylinder of a same diameter as the replaced buffer tube55. The replacement reduces the fiber count of the hybrid cable11′. The hybrid cable11′ includes only eleven buffer tubes37,39,41,43,45,47,49,51,53,57and59, each with twelve optical fibers, making a fiber count of the hybrid cable11one hundred thirty two fibers.

FIG.4is a front perspective view of a hybrid cable101in accordance with a second embodiment of the present invention.FIG.5is a cross sectional view taken along line V-V inFIG.4. The hybrid cable101includes a core103with two large insulated conductors105and107.

A central strength member109resides in a center of the core103. The central strength member109is flanked by first and second buffer tubes111and113. Each of the first and second buffer tubes111and113includes at least one optical fiber, such as four, six, eight, ten or twelve optical fibers.FIGS.4-5illustrate twelve optical fibers loosely contained within a water blocking gel of each of the first and second buffer tubes111and113, making a total of 24 optical fibers in the hybrid cable101. A water-blocking tape115surrounds the two large insulated conductors105and107, the central strength member109and the first and second buffer tubes111and113to form the core103.

In a preferred embodiment, the two large insulated conductors105and107are each formed by a twelve AWG conductor, such as a stranded copper wire, which is in turn surrounded by a dielectric insulation layer. The central strength member109may be formed as a GRP rod.

A shielding layer117surrounds the core103. In the illustrated embodiment, the shielding layer117is formed by corrugated aluminum. However, other materials may be used to form the shielding layer117.

A jacket119surrounds the shielding layer117. The jacket119may include one or more stripes119A of a contrasting color, to help identify the cable. For example, the majority of the jacket119may be black and the one or more stripes119A may be red. A first plurality of textile strength elements121is located between the water-blocking tape115and the shielding layer117. In one embodiment, the first plurality of textile strength elements121includes ten bundles of fibers, e.g.,121A—121J, each of which extends longitudinally along the length of the hybrid cable101.

A second plurality of textile strength elements123is located between the water-blocking tape115and the two large insulated conductors105and107, the central strength member109and the first and second buffer tubes111and113. In the embodiment ofFIGS.4and5, the second plurality of textile strength elements123includes a first grouping123A and a third grouping123C of textile strength elements helically wrapped around the two large insulated conductors105and107, the central strength member109and the first and second buffer tubes111and113in a first wrapping direction. The second plurality of textile strength elements123also includes a second grouping123B and a fourth grouping123D of textile strength elements helically wrapped around the two large insulated conductors105and107, the central strength member109and the first and second buffer tubes111and113in a second wrapping direction, opposite to the first wrapping direction.

The first and third groupings123A and123C of textile strength elements cross over the second and fourth groupings123B and123D of textile strength elements to hold the two large insulated conductors105and107, the central strength member109and the first and second buffer tubes111and113together during assembly of the hybrid cable101, so that the water-blocking tape115may be wrapped there around to form the core103.

In a preferred embodiment, the first and second pluralities of textile strength elements121and123are formed of flaccid threads, like aramid fibers, sold under the trademark KELVAR. In a preferred embodiment, the hybrid cable101may also include first and second ripcords125and127located between the water-blocking tape115and the shielding layer117. The first and second ripcords125and127assist in opening up an end of the hybrid cable101for a termination to connectors.

In the embodiment ofFIGS.4and5, no filler rods are employed.FIG.6is a cross sectional view similar toFIG.5of a hybrid cable101′. The hybrid cable101′ is an alternative to the hybrid cable101. InFIG.6, four filler rods129,131,133and135are added to the core103. Each of the four filler rods129,131,133and135is not in abutment with the central strength member109, but is in abutment with the inside surface of the water-blocking tape115.

The four filler rods129,131,133and135cause the core103to assume a very circular outer profile, which would commonly be seen as necessary to accomplish a circular outer profile to the cross section of the overall hybrid cable101′. However, surprisingly, the Applicant has discovered that if the four first filler rods129,131,133and135are omitted, the outer profile of the cross section of the overall hybrid cable101can still be made circular. Therefore, the embodiment shown inFIGS.4and5is preferred over the alternative, depicted inFIG.6, as the hybrid cable101remains circular in its outer profile while sparing the costs, added weight and assembly steps associated with the four filler rods129,131,133and135.

FIG.7is a front perspective view of a hybrid cable201in accordance with a third embodiment of the present invention.FIG.8is a cross sectional view taken along line VIII-VIII inFIG.7. The hybrid cable201includes a core203with two large insulated conductors205and207.

A central strength member209resides in a center of the core203. The central strength member209is flanked by a single buffer tube211. The single buffer tube211includes at least one optical fiber, such as four, six, eight, ten or twelve optical fibers, preferably surrounded by a gel, such as a water blocking gel, within the buffer tube.FIGS.7-8illustrate twelve optical fibers loosely contained within the single buffer tube211, making a total of 12 optical fibers in the hybrid cable201. A water-blocking tape215surrounds the two large insulated conductors205and207, the central strength member209and the single buffer tube211to form the core203.

In a preferred embodiment, the two large insulated conductors205and207are each formed by a twelve AWG conductor, such as a stranded copper wire, which is in turn surrounded by a dielectric insulation layer. The central strength member209may be formed as a GRP rod.

A shielding layer217surrounds the core203. In the illustrated embodiment, the shielding layer217is formed by corrugated aluminum. However, other materials may be used to form the shielding layer217.

A jacket219surrounds the shielding layer217. The jacket219may include one or more stripes219A of a contrasting color, to help identify the cable. For example, the majority of the jacket219may be black and the one or more stripes219A may be red. A first plurality of textile strength elements221is located between the water-blocking tape215and the shielding layer217. In one embodiment, the first plurality of textile strength elements221includes ten bundles of fibers, e.g.,221A—221J, each of which extends longitudinally along the length of the hybrid cable201.

A second plurality of textile strength elements223is located between the water-blocking tape215and the two large insulated conductors205and207, the central strength member209and the single buffer tube211. In the embodiment ofFIGS.7and8, the second plurality of textile strength elements223includes a first grouping223A and a third grouping223C of textile strength elements helically wrapped around the two large insulated conductors205and207, the central strength member209and the single buffer tube211in a first wrapping direction. The second plurality of textile strength elements223also includes a second grouping223B and a fourth grouping223D of textile strength elements helically wrapped around the two large insulated conductors205and207, the central strength member209and the single buffer tube211in a second wrapping direction, opposite to the first wrapping direction.

The first and third groupings223A and223C of textile strength elements cross over the second and fourth groupings223B and223D of textile strength elements to hold the two large insulated conductors205and207, the central strength member209and the single buffer tube211together during assembly of the hybrid cable201, so that the water-blocking tape215may be wrapped there around to form the core203.

In a preferred embodiment, the first and second pluralities of textile strength elements221and223are formed of flaccid threads, like aramid fibers, sold under the trademark KELVAR. In a preferred embodiment, the hybrid cable201may also include first and second ripcords225and227located between the water-blocking tape215and the shielding layer217. The first and second ripcords225and227assist in opening up an end of the hybrid cable201for a termination to connectors.

In the embodiment ofFIGS.7and8, no filler rods are employed.FIG.9is a cross sectional view similar toFIG.8of a hybrid cable201′. The hybrid cable201′ is an alternative to the hybrid cable201. InFIG.9, three filler rods229,231and233are added to the core203. Each of the three filler rods229,231and233is not in abutment with the central strength member209, but is in abutment with the inside surface of the water-blocking tape215. The three filler rods229,231and233cause the core203to assume a very circular outer profile, so that a circular outer profile is also achieved in the cross section of the overall hybrid cable201′.

FIG.10is a front perspective view of a hybrid cable11A. The hybrid cable11A is the same as the hybrid cable11ofFIGS.1and2, but includes a first embodiment of a toning signal medium. The central core13, concentric core31and the first, second and third pluralities of textile strength elements67,69and71are the same as depicted inFIGS.1and2. Therefore, the elements have not been separately labeled.

InFIG.10, the toning signal medium takes the form of an insulated wire93. The insulated wire93coils around the outer surface of the shielding layer63in a helical fashion. In a preferred embodiment, the pitch P of the helix is between six inches and twenty-four inches. Electrical isolation between the insulated wire93and the shielding layer63is maintained by at least the insulation layer on the insulated wire93. Also, in the preferred embodiment, the gauge of the conductor within the insulated wire93is eighteen AWG. As the insulated wire93is present during the extrusion of the jacket65over the shielding layer63, the thickness of the jacket65accommodates the diameter of the insulated wire93, and permits the outer surface of the jacket65to remain approximately circular in cross section.

FIG.11is a front perspective view of a hybrid cable11B. The hybrid cable11B is the same as the hybrid cable11ofFIGS.1and2, but includes a second embodiment of a toning signal medium. The central core13, concentric core31and the first, second and third pluralities of textile strength elements67,69and71are the same as depicted inFIGS.1and2. Therefore, the elements have not been separately labeled.

InFIG.11, the toning signal medium takes the form of a conductive track95. The conductive track95is a small inner portion of the jacket65which is highly doped with conductive segments, e.g., carbon fibers, copper mesh, conductive threads, etc. Due to the segmented structure of the conductive elements some flexibility is permitted without risking the breaking of the many conductive paths established throughout the conductive track95. Electrical isolation between the conductive track95and the shielding layer63can be obtained by the formation of a coating or layer, e.g., MYLAR, on the outside surface the shielding layer63.

FIG.12is a front perspective view of a hybrid cable11C. The hybrid cable11C is the same as the hybrid cable11ofFIGS.1and2, but includes a third embodiment of a toning signal medium. The central core13, concentric core31and the first, second and third pluralities of textile strength elements67,69and71are the same as depicted inFIGS.1and2. Therefore, the elements have not been separately labeled.

InFIG.12, the toning signal medium takes the form of a conductive ink or elastic element97. The conductive ink or elastic element97is a linear stripe of the outer surface of the jacket65. Electrical isolation between the conductive ink or elastic element97and the shielding layer63is obtained by the intervening jacket65.

FIG.13is a front perspective view of a hybrid cable11D. The hybrid cable11D is the same as the hybrid cable11ofFIGS.1and2, but includes a fourth embodiment of a toning signal medium. The central core13, concentric core31and the first, second and third pluralities of textile strength elements67,69and71are the same as depicted inFIGS.1and2. Therefore, the elements have not been separately labeled.

InFIG.13, the toning signal medium takes the form of a conductive layer99. The conductive layer99is similar to a shielding layer, and may be formed of a conductive foil and/or braided conductive wires, e.g., commonly used as a shielding layer of a coaxial cable. The conductive layer99is formed over the jacket65, so that electrical isolation between the conductive layer99and the shielding layer63is obtained by the intervening jacket65. An outer sleeve98, which may be formed as an extruded outer jacket, may be applied over the conductive layer99.

FIGS.10-13have shown the toning signal mediums93,95,97and99in combination with the hybrid cable11ofFIGS.1and2. However, the toning signal mediums93,95,97and99may also be used in combination with the hybrid cables11′,101,101′,201and201′ ofFIGS.3-9.