BACKGROUND OF THE INVENTION

1. Field of the Invention

[001] The present invention relates to a hybrid cable having both electrical conductors for power and one or more communication carrying mediums, such as optical fibers. More particularly, the present invention relates to a hybrid cable wherein the components, e.g., electrical connectors and a buffer tube with one or more optical fibers therein, share a common extruded jacket, centers of the components are not linearly aligned, and the components may be manually pulled apart from each other.

2. Description of the Background

[002] Cables with components which share a common extruded jacket and may be pulled apart from each other are generally known in the prior art. For example, see US Patents 4,220,812; 4,729,628; 5,180,890; 5,602,953; 6,563,990; 6,734,364; 9,472,314; 10,163,548; 10,497,493 and 10,892,068, and US Published Applications 2015/0309271 and 2018/0052293, each of which is herein incorporated by reference. As best seen in Figure 1, the Assignee’s cable 11, as shown in US Patent 9,472,314, has a generally flat configuration with a major axis X and a minor axis Y. The major axis X passes through centers of the various components 13 of the flat cable, such as electrical conductors 13 A and a buffer tube 13B with an optical fiber 13C.

[003] As the cable 11 is flat, the cable 11 has a bend preference. More particularly, the cable 11 tends to easily bend in the directions of the minor axis Y. However, it is very difficult to bend the cable 11 in the directions of the major axis X. This is a disadvantage when the cable 11 is pushed into a conduit or plenum. Conduits and plenum can have plural curves and comers, some of which will not be aligned to the minor axis Y of the cable 11. The cable 11 will tend to abut into, and stop at, a curve or corner, which requires a bend in the directions of the major axis X.

[004] Hybrid cables which include one or more electrical conductors and one or more optical fibers are also known in prior art. For example, see US Patents 5,469,523; 6,363,192; 6,734,364; 7,049,523; 7,259,332; 8,929,702; 9,165,698; 9,322,704; 9,581,778 and 10,008,309, each of which is herein incorporated by reference. As best seen in Figure 2, many hybrid cables are formed as round cables 15 with a major axis X and a minor axis Y. In contrast to the flat cable 11, the major axis X does not pass through centers of the various components 13A, 13B and 13C of the round cable 15. Hence, the round cable 15 is freer to bend in plural directions and does not strongly prefer the directions aligned to the major axis X or the minor axis Y, as with the flat cable 11.

[005] Each of the electrical conductors 13 A of the round cable 15 has its own insulation layer 17. An extruded, outer jacket 19 is spaced and separate from the insulation layers 17 of the electrical conductors 13A and the buffer tube 13B surrounding optical fibers 13C. The outer jacket 17 prevents the components 13 from being manually separated, e.g., pulled apart. Typically, a tool is used to ring cut and then strip the outer jacket 19 off of an end of the round cable 15 to expose the components 13 of the round cable 15.

SUMMARY OF THE INVENTION

[006] It is an object of the present invention to provide a hybrid cable with an improved bend performance as compared to flat cable designs, wherein the components may be pulled apart and manually separated. In other words, no outer jacket needs to be removed in order to separate the components of the cable from each other.

[007] It is a further object of the present invention to provide a hybrid cable wherein the components share a common jacket extruded directly onto the components, e.g., the buffer tube, the electrical conductors, the outer conductor of a coaxial cable, etc.

[008] These and other objectives are accomplished by a hybrid cable including first and second electrical conductors and a communication carrying medium, such as one or more optical fibers surrounded by a buffer tube, or a twisted pair or a coaxial cable. A spine interconnects the first and second electrical conductors and the communication carrying medium. The spine includes at least an outer layer formed by a dielectric material, which also completely covers and forms insulation jackets about the first and second electrical conductors and the communication carrying medium. Vacant valleys extend toward a central axis of the spine between each of the first and second electrical conductors and the communication carrying medium, which valleys improve the flexibility of the hybrid cable in different directions. In a termination process, the spine can be cleanly removed from the insulation jackets of the first and second electrical conductors and communication carrying medium by manually pulling the insulation jackets away from the spine.

[009] Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[010] For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

[011] Figure 1 is a perspective view of a flat cable with pull-apart components, in accordance with the prior art;

[012] Figure 2 is a cross sectional view of a hybrid cable with a circular outer jacket to hold the components together, in accordance with the prior art;

[013] Figure 3 is a perspective view of an end of a hybrid cable, in accordance with the present invention;

[014] Figure 4 is a cross sectional view taken along line IV— IV in Figure 3;

[015] Figure 5 is a perspective view of a longer section the hybrid cable of Figure 3;

[016] Figure 6 is a cross sectional view, similar to Figure 4, illustrating a hybrid cable in accordance with a second embodiment of the present invention;

[017] Figure 7 is a perspective view, similar to Figure 3, illustrating a hybrid cable, in accordance with a third embodiment of the present invention; [018] Figure 8 is a cross sectional view illustrating a hybrid cable, in accordance with a fourth embodiment of the present invention;

[019] Figure 9 is a cross sectional view, similar to Figure 4, illustrating a hybrid cable, in accordance with a fifth embodiment of the present invention; and

[020] Figure 10 is a cross sectional view, similar to Figure 4, illustrating a hybrid cable, in accordance with a sixth embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[021] The present invention now is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[022] 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.

[023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.

[024] As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. As used herein, phrases such as "between X and Y" and "between about X and Y" should be interpreted to include X and Y. As used herein, phrases such as "between about X and Y" mean "between about X and about Y." As used herein, phrases such as "from about X to Y" mean "from about X to about Y."

[025] It will be understood that when an element is referred to as being "on", "attached" to, "connected" to, "coupled" with, "contacting", etc., another element, it can be directly on, attached to, connected to, coupled with or contacting the other element or intervening elements may also be present. In contrast, when an element is referred to as being, for example, "directly on", "directly attached" to, "directly connected" to, "directly coupled" with or "directly contacting" another element, there are no intervening elements present. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed "adjacent" another feature may have portions that overlap or underlie the adjacent feature.

[026] Spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper”, “lateral”, “left”, “right” and the like, may be used herein for ease of description to describe one element or feature’s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the descriptors of relative spatial relationships used herein interpreted accordingly.

[027] Figure 3 is a perspective view of an end of a hybrid cable 21 and Figure 4 is a cross sectional view taken along line IV— IV in Figure 3. The hybrid cable 21 includes several components. In a preferred embodiment, components to deliver power are included. For example, a first electrical conductor 23 is formed of a conductive metal or alloy and has a first insulation layer 25 surrounding and completely covering the first electrical conductor 23. A second electrical conductor 27 is formed of a conductive metal or alloy and has a second insulation layer 29 surrounding and completely covering the second electrical conductor 27. In a preferred embodiment, the first and second electrical conductors 23 and 27 are sized between 20 American wire gauge (AWG) and 12 AWG, although other sizes are possible. The first and second electrical conductors 23 and 27 may each be formed as a stranded bunch of smaller wires or as a one-piece solid wire, e.g., copper or copper-clad-steel, as will be further described hereinafter.

[028] In the preferred embodiment, communication signal carrying components are also included in the hybrid cable 21. For example, a first optical fiber 31 is surrounded by a first buffer tube 33 and a third insulation layer 35 surrounds and completely covers the first buffer tube 33. Optionally, a first plurality of strength threads 34 surround the first buffer tube 33 and are located between the first buffer tube 33 and the third insulation layer 35. The first plurality of strength threads 34 may be formed of aramid yams, sold under the trademark KELVAR.

[029] The first optical fiber 31 may be a single mode or multimode optical fiber. The first optical fiber 31 may be surrounded by the first buffer tube 33 in either a loose tube arrangement or a tight tube arrangement. One or more additional optical fibers may also be included within the first buffer tube 33 along with the first optical fiber 31, as will be further described hereinafter.

[030] In the middle of the hybrid cable 21, there is provided a spine 37. The spine 37 has a central axis A. A central strength member 39 is optionally embedded within the spine 37. The central strength member 39 is centered about the central axis A of the spine 37. In one embodiment, the central strength member 39 is formed as a flexible, glass reinforced plastic (GRP) rod, or a solid or stranded messenger wire.

[031] The spine 37 also includes first, second and third extension members 41, 43, and 45 attached to the first, second and third insulation layers 25, 29 and 35. The first, second and third extension members 41, 43 and 45 extend away from the central axis A in first, second and third directions 47, 49 and 51, respectively. At least the first and third directions 47 and 51 are not linearly aligned and are not parallel. In a preferred embodiment, the first and second directions 47 and 49 are not linearly aligned and are not parallel, the second and third directions 49 and 51 are not aligned and are not parallel, and the first and third directions 47 and 51 are not linearly aligned and are not parallel.

[032] Another way to characterize the non-linear alignments between the components of the hybrid cable 21 would be to consider that first electrical conductor 23 has a first center axis 23a, the second electrical conductor 27 has a second center axis 27a and the first buffer tube 33 has a third center axis 33a. If a first plane includes the first center axis 23a and the second center axis 27a, the third center axis 33a does not reside within the first plane. The non-linear arrangement of the three components is even more pronounced when no part of the first buffer tube 33 passes through the first plane, as is shown in Figure 4.

[033] An important aspect of the present invention is that the spine 37 includes at least an outer layer 53 formed of a dielectric material, e.g., an insulator material like PVC or another polymer common to the cable art, and that the first insulation layer 25, the second insulation layer 29 and the third insulation layer 35 are integrally formed of the dielectric material forming the outer layer 53 of the spine 37. In a preferred embodiment, the first, second and third insulation layers 25, 29 and 35 are integrally formed by a single extrusion process along with the outer layer 53 of the spine 37. When the spine 37 includes the central strength member 39, the outer layer 53 of the spine 37 may be constituted by all parts of the spine 37 which envelope the central strength member 39. When the spine 37 does not include the central strength member 39, the entirety of the spine 37 may be uniformly extruded of the dielectric material forming the outer layer 53 of the spine 37. During manufacturing, the components of the hybrid cable 21 are fed to an assembling area, e.g., a crosshead die, and insulation is extruded over the components, e.g., the central strength member 31, the first electrical conductor 23, the second electrical conductor 27 and the first buffer tube 33, so as to completely cover the components and to form vacant valleys 55, 57 and 59 extending toward the central axis A of the spine 37 between each of the first electrical conductor 23, the second electrical conductor 27 and the first buffer tube 33.

[034] Figure 5 is a perspective view of a longer section the hybrid cable 21 of Figure 3. Figure 5 shows that the first electrical conductor 23, the second electrical conductor 27 and the first buffer tube 33 have a twist or strand lay about the central axis A of the spine 37. In Figure 5, length L represents the length of hybrid cable 21 needed for the second electrical conductor 27 to take over the o’clock position of the first buffer tube 33 due to the twist or strand lay of the hybrid cable 21. As it would take three times the length L for the second electrical conductor 27 to reach its original o’clock position, the twist or strand lay of the hybrid cable 21 is the length 3L. In a preferred embodiment, the value for 3L is about one meter or greater. However, other values for the strand length of the hybrid cable 21 are within the purview of the present invention, such as 3L is about 10 to 300 centimeters, or about 20 to 200 centimeters. The stranding of the hybrid cable 21 greatly enhances the ability of the hybrid cable 21 to bend in various directions, e.g., any direction, three hundred sixty degrees about the central axis A.

[035] Figure 6 is a cross sectional view, similar to Figure 4, but illustrating a hybrid cable 21 A in accordance with a second embodiment of the present invention. The hybrid cable 21 A illustrates that the spine 37A does not necessarily include a central strength member 39. Also, the first buffer tube 33 A may be made with a different, e.g., thinner, wall thickness. A second optical fiber 61 may also be surrounded by the first buffer tube 33A. The first and second optical fibers 31 and 61 are in a loose tube arrangement within the first buffer tube 33 A. The first buffer tube 33A may also include at least one water swellable thread or tape 63 or a water blocking gel disposed within the first buffer tube 33A, or both. Optionally, one or more rip cords 65, formed of a strong thread, may be included within the first buffer tube 33 A.

[036] Figure 7 is a perspective view, similar to Figure 3, illustrating a hybrid cable 21B in accordance with a third embodiment of the present invention. The hybrid cable 2 IB once again has a central strength member 39 within the spine 37. The first electrical conductor 23 A is shown a being formed of stranded wires, e.g., nineteen copper wires stranded to form a 20 to 12 AWG conductor, instead of a solid conductor as illustrated in Figures 3-6. Likewise, the second electrical conductor 27A is shown as being formed of stranded wires instead of a solid conductor as illustrated in Figures 3-6. The stranded wires of the first and second electrical conductors 23A and 27A may improve the current carrying capacity and the overall flexibility of the hybrid cable 21B.

[037] In the embodiment of Figure 7, the first buffer tube 33 A is shown surrounding a plurality of optical fibers 67, such as twelve optical fibers of the single mode type. The plurality of optical fibers 67 may be attached to a rollable ribbon. Alternatively, the plurality of optical fibers 67 may be loosely held within the first buffer tube 33 A, or may be formed as stacked arrays, e.g., three stacked arrays having four optical fibers each.

[038] Figure 8 is a cross sectional view illustrating a hybrid cable 21C in accordance with a fourth embodiment of the present invention. The hybrid cable 21C further includes a second optical fiber 61 A tightly surrounded by a second buffer tube 69, with a fourth insulation layer 71 completely surrounding the second buffer tube 69. Optionally, a second plurality of strength threads 70 surround the second buffer tube 69 and are located between the second buffer tube 69 and the fourth insulation layer 71. The second plurality of strength threads 70 may be formed of aramid yams, sold under the trademark KELVAR.

[039] The spine 37A includes a fourth extension member 73, which is attached to the fourth insulation layer 71. The fourth extension member 73 extends away from the central axis A in a fourth direction 75, which is not linearly aligned with either of the second or third directions 49 or 51, but may optionally be aligned with the first direction 47. The second buffer tube 69 has a fourth center axis 69a. The fourth center axis 69a does not reside within a first plane including the first center axis 23a and the center axis 27a of the first and second electrical conductors 23 and 27. The spine 37A interconnects the second buffer tube 69 to the first electrical conductor 23, the second electrical conductor 27 and the first buffer tube 33. The dielectric material of the outer layer 53 of the spine 37A is integrally formed with the first insulation layer 25, the second insulation layer 29, the third insulation layer 35 and the fourth insulation layer 71. The dielectric material also completely covers the second buffer tube 69, and vacant valleys extend toward the central axis A of the spine 37A on each side of the second buffer tube 69.

[040] Figure 9 is a cross sectional view, similar to Figure 4, illustrating a hybrid cable 2 ID, in accordance with a fifth embodiment of the present invention. The fifth embodiment of Figure 9 is the same as the first embodiment of Figure 4, except that the communication carrying medium is different. In Figure 9, the communication carrying medium is formed by a twisted pair, i.e., a first insulated conductor 77 twisted in a helix with a second insulated conductor 79. The dielectric material of the outer layer 53 of the spine 37 is integrally formed with the first insulation layer 25, the second insulation layer 29 and the third insulation layer 35, with the third insulation layer 35 performing the function of a jacket for the twisted pair and completely surrounding the twisted first and second insulated conductors 77 and 79. Of course, more than one twisted pair may be included within the third insulation layer 35, if desired.

[041] Figure 10 is a cross sectional view, similar to Figure 4, illustrating a hybrid cable 2 IE, in accordance with a sixth embodiment of the present invention. The sixth embodiment of Figure 10 is the same as the first embodiment of Figure 4, except that the communication carrying medium is different. In Figure 10, the communication carrying medium is formed as a coaxial cable, i.e., a center conductor 81 surrounded by a dielectric layer 83, which is in turn surrounded by an outer conductive shielding layer 85. The dielectric material of the outer layer 53 of the spine 37 is integrally formed with the first insulation layer 25, the second insulation layer 29 and the third insulation layer 35, with the third insulation layer 35 performing the function of a jacket for the coaxial cable and completely surrounding the outer conductive shielding layer 85.

[042] A method of making a hybrid cable would include advancing a first electrical conductor into a crosshead die of an extruder; advancing a second electrical conductor into the crosshead die of the extruder, wherein a first plane passes through a first center axis of the first electrical conductor and through a second center axis of the second electrical conductor. A communication carrying medium is simultaneously advanced into the crosshead die of the extruder, wherein a third center axis of the communication carrying medium does not reside within the first plane. The extruder extrudes a dielectric material over the first electrical conductor, the second electrical conductor and the communication carrying medium to form a dielectric jacket which (1) completely covers the first electrical conductor, the second electrical conductor and the communication carrying medium, (2) forms a spine interconnecting the first electrical conductor, the second electrical conductor and the communication carrying medium, and (3) forms vacant valleys extending toward the spine between each of the first electrical conductor, the second electrical conductor and the communication carrying medium.

[043] In a preferred embodiment of the method of manufacturing, the communication carrying medium includes at least one optical fiber surrounded by a buffer tube, and no part of the buffer tube passes through the first plane. Also in the preferred embodiment of manufacturing, a central strength member is simultaneously advanced into an area within the crosshead die between the first electrical conductor, the second electrical conductor and the communication carrying medium. The central strength member, e.g., a GRP rod, is then embedded into the spine during the extruding of the dielectric material. Also in the preferred embodiment of manufacturing, the central strength member, the first electrical conductor, the second electrical conductor and the communication carrying medium are completely covered by the dielectric material and the connections between the spine and the first electrical conductor, the second electrical conductor and the communication carrying medium are continuous over the length of the hybrid cable.

[044] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.