Abstract:
A cable and system for manufacturing the same is provided. The cable includes a core communications medium and an outer jacket surrounding the core communications medium. A plurality of grooves are in the outer surface of the outer jacket. Each of the grooves has a recess and an opening to access the recess, the recess having a larger width than the opening. Each of the plurality of conductors is exposed to the external environment and can be reached directly from the external environment.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to undersea cables. More specifically, the present invention relates to undersea cables with a helical grooved outer jacket that can support multiple conductors.  
         [0003]     2. Discussion of Background Information  
         [0004]     Commercially available undersea cables typically include a core cable, a protective cover around the cable, and a series of conductors (metal or fiber-optic) embedded in the cover that carry signals separate from the main core cable. One must cut into the protective cover to access these conductors, which places the underlying main core cable at risk of damage. Conductors can typically be placed near the surface of the protective cover to minimize the cut depth needed to access the conductors, which minimizes potential damage to the underlying main core cable. However, the reduction in thickness of the overlapping protective cover results in a corresponding loss of protection for the conductors.  
       SUMMARY OF THE INVENTION  
       [0005]     According to an embodiment of the invention, a cable is provided. The cable includes a core communications medium and an outer jacket surrounding the core communications medium. A plurality of grooves are in the outer surface of the outer jacket. Each of the grooves has a recess and an opening to access the recess, the recess having a larger width than the opening. Each of the plurality of conductors is exposed to the external environment and can be reached directly from the external environment.  
         [0006]     The above embodiment may have various features. The outer jacket may include an extrusion grade, abrasion resistant polyether-based thermoplastic polyurethane with a durometer of between and including 74 to 85 Shore A; the outer jacket may include a lubricant mixed with polyurethane. The plurality of grooves may each have a substantially circular cross section. The core communications medium may be an unarmored fiber optic cable, either with or without its outer jacket.  
         [0007]     According to another embodiment of the invention, a communications cable is provided. The cable includes a core communications medium and an outer jacket surrounding the core communications medium. A plurality of helical grooves are in the outer surface of the outer jacket. Each of the grooves has a recess and an opening to access the recess, the recess having a larger width than the opening. A communications cable is laid in each of the grooves. Each communications cable has a diameter less than or equal to a width of the recess, but greater than a width of the opening.  
         [0008]     The above embodiment may have various features. The outer jacket may include an extrusion grade, abrasion resistant polyether-based thermoplastic polyurethane with a durometer of between and including 74 to 85 Shore A; the outer jacket may include a lubricant mixed with polyurethane. The plurality of grooves may each have a substantially circular cross section. The core communications medium may be an unarmored fiber optic cable, either with or without its outer jacket.  
         [0009]     According to still another embodiment of the invention, a communications cable is provided. The cable includes a core communications medium and an outer jacket surrounding the core communications medium. The outer jacket at least partially including an extrusion grade, abrasion resistant polyether-based thermoplastic polyurethane with a durometer of between and including 74 to 85 Shore A. A plurality of helical grooves are in the outer surface of the outer jacket. Each of the grooves has a recess and an opening to access the recess, the recess having a substantially circular cross section and a diameter larger than the opening. A communications cable is laid in each of the grooves, each cable having a diameter less than or equal to the diameter of the recess, but greater than a width of the opening.  
         [0010]     The above embodiment may have various features. The outer jacket may include an extrusion grade, abrasion resistant polyether-based thermoplastic polyurethane with a durometer of between and including 74 to 85 Shore A. The outer jacket may include a lubricant mixed with polyurethane. The plurality of,grooves may each have a substantially circular cross section. The core communications medium may be an unarmored fiber optic cable, either with or without its outer jacket. Each of the plurality of communications cables may be exposed to the external environment and can be accessed directly from the external environment.  
         [0011]     According to yet another embodiment of the invention, a method for manufacturing a communications cable is provided. The steps include applying adhesive to a cable, preheating the cable and applied adhesive, passing the cable with adhesive through a die, the die being configured to form an outer jacket with grooves therein over the cable, rotating the die during the passing, extruding a compound around the cable with adhesive during the rotating, cooling the compound, cable and adhesive to form a cable with an outer jacket having grooves, and laying individual communication cables in the grooves.  
         [0012]     The above embodiment may have various features. There may be an additional step of forming the compound by mixing a lubricant with an extrusion grade, abrasion resistant polyether-based thermoplastic polyurethane with a durometer of between and including 74 to 85 Shore A. There may be an additional step of winding the cable over a spool, which may precede or follow the step of laying.  
         [0013]     According to yet another embodiment of the invention, a method for manufacturing a communications cable is provided. The method includes removing an outer layer of a cable, preheating the cable, passing the cable through a die, the die being configured to form an outer jacket with grooves therein over the cable, rotating the die during the passing, extruding a compound around the cable during the rotating, cooling the compound and cable to form a cable with an outer jacket having grooves, and laying individual communication cables in the grooves.  
         [0014]     The above embodiment may have various features. There may be an additional step of forming the compound by mixing a lubricant with an extrusion grade, abrasion resistant polyether-based thermoplastic polyurethane with a durometer of between and including 74 to 85 Shore A. There may be an additional step of winding the cable over a spool, which may precede or follow the step of laying. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of certain embodiments of the present invention, in which like numerals represent like elements throughout the several views of the drawings, and wherein:  
         [0016]      FIG. 1  illustrates a perspective view of a cable according to an embodiment of the invention;  
         [0017]      FIG. 2  illustrates a side view of the outer jacket of the embodiment of  FIG. 1  over a single pitch of the helicoid on the outer jacket;  
         [0018]      FIG. 3  illustrates a cross section taken along line A-A in  FIG. 2 ;  
         [0019]      FIG. 4  illustrates the cross section of  FIG. 3  with reference circles;  
         [0020]      FIG. 5  illustrates a perspective view of a cable according to another embodiment of the invention;  
         [0021]      FIG. 6  illustrates a side view of the outer jacket of the embodiment of  FIG. 5  over single pitch of the helicoid on the outer jacket;  
         [0022]      FIG. 7  illustrates a cross section taken along line A-A in  FIG. 6 ; and  
         [0023]      FIG. 8  illustrates an additional cross section view taken along line A-A in  FIG. 6 . 
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0024]     The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.  
         [0025]     Referring to  FIG. 1 , an embodiment  100  includes an outer jacket  102  concentrically about a core cable  104 . Cable  104  is preferably any commercially available unarmored cable used in undersea operations, although any commercially available cable could be used. Jacket  102  is preferably an extruded polyurethane structure which holds and protects cable  104  substantially coaxially therewith. Referring now also to  FIG. 2 , jacket  102  includes several equally spaced helical grooves  106  around its outer periphery. The grooves form a so-called “left hand lay,” which matches the lay of commercial undersea cables.  
         [0026]      FIG. 3  shows a cross section of the embodiment  100  taken across line A-A in  FIG. 2 , which exposes the core cable  104  and the surrounding jacket  102 . An adhesive layer  108  separates and joins cable  104  and jacket  102 .  FIG. 4  shows individual conductors  110  placed in each of grooves  106 . The embodiments herein show eight grooves  106 , but any number may be used.  
         [0027]     Jacket  102  includes projections  112  that define each of the individual grooves  106 . The groves are substantially circular in shape with an opening.  114  facing outward, although other non-circular shapes could be used. Opening  114  is preferably smaller than the diameter of conductors  110  so that conductors  110  will not fall out (absent intentional efforts to remove them), but wide enough such that conductors  110  can be popped into grooves  106  under the application of suitable external pressure. The inwardly facing edges of projections  112  adjacent opening  114  and the apex of projections  112  are preferably rounded to ease in cable insertion.  
         [0028]     Jacket  102  provides protection for both core cable  104  and conductors  110 . However, a technician can access individual conductors  110  simply by popping them right out of the groove  106 . There is no need to cut into protective jacket  102 , and thus no corresponding risk of damaging core cable  104 .  
         [0029]     The dimensions of embodiment  100  are highly dependent upon the nature of cable  104  and conductors  110 . An unarmored commercial cable  104  typically has a diameter of 0.882 inches, and commercially available conductors  110  typically have a diameter of 0.260 inches. For cables and conductors of such dimensions, then embodiment  100  may have the following parameters:  
         [0030]     Adhesive  108  is preferably approximately 0.03 inches thick, ±0.0075 inches. Since adhesive  108  surrounds cable  104 , the diameter of cable  104  and adhesive  108  is preferably approximately 0.935±0.015 inches.  
         [0031]     The distance between the outer diameter of adhesive  108  and the inner diameter of grooves  106  is preferably 0.195 inches, ±0.0375 inches.  
         [0032]     The centers of each of conductors  110  preferably define a circle having a diameter of approximately 1.43 inches.  
         [0033]     The outer diameter of jacket  102  is preferably 1.95-2.10 inches.  
         [0034]     The diameter of the circular portion of groove  106  is preferably 0.270-0.330 inches.  
         [0035]     The width of opening  114  is preferably 0.170-0.330 inches.  
         [0036]     The edges of projections  112  adjacent opening  114  preferably have a radius of curvature of 0.050 inches.  
         [0037]     The outermost edges of projections  112  preferably have a radius of curvature of 0.030 inches.  
         [0038]     The length of a single turn (360° revolution) of one of grooves  106  is preferably 16-17.5 inches.  
         [0039]     The minimum bend radius for embodiment  100  is preferably approximately 40 inches if the cable tension is less than 2000 lbs, and preferably approximately 60 inches if the cable tension is greater than or equal to 2000 lbs.  
         [0040]     Jacket  102  is preferably made primarily from an extrusion grade, abrasion resistant polyether-based thermoplastic polyurethane with a durometer of between (and including) 74 to 85 Shore A. Below 74 would be sufficiently soft that it may not hold conductors  110  in place, whereas above 85 would be sufficiently hard that projections  112  would not bend under pressure to enlarge opening  114  to allow insertion of conductors  110 . Elastolan 1175A1OW is suitable for this purpose, although other compounds may be used.  
         [0041]     The jacket  102  compound includes polyurethane having the characteristics noted above and approximately 0.10%±0.05% lubricant. The lubricant will reduce the coefficient of sliding friction of the polyurethane during extrusion. Americhem 44192 is suitable for this purpose, although other compounds may be used.  
         [0042]     The manufacturing process is as follows. Cable  104  is first fed into a system which applies adhesive  108  in an appropriate thickness. The cable  104  with adhesive  108  is then preheated to approximately 330-370 degrees F., particularly 350 degrees F., before being fed to a rotating die (not shown). The die has a cross section that substantially mirrors that shown in  FIG. 3 , modified as necessary to account for post-extrusion changes such as shrinkage. The polyurethane compound is extruded around cable  104  as it passes through the rotating die. Rotation of the die creates the helical exterior shape of jacket  102 . Preferably approximately 1 foot of cable is extruded per minute. Jacket  102  is then cooled (under ambient temperature, fans, or other cooling systems) for approximately 1 hour before the finished product is wound on a spool.  
         [0043]     Individual conductors  110  are preferably added at a later date, although they could also be added before the cable is wound; in either case, portions of conductors  110  are aligned with grooves  106  and subject to inward radial pressure to force the conductors  110  through opening  114  into grooves  106 . This process repeats along with length of the cable.  
         [0044]     A perspective view of another embodiment  500  of the invention is shown in  FIG. 5 . A cable  504  is preferably a commercially available armored cable with its “tar and jute” (its outer nylon coating) removed, but other cables may be used. Since the polyurethane compound will easily bond with cable  504 , no adhesive layer is necessary. A jacket  502  is identical to jacket  102  discussed above.  
         [0045]     The dimensions of embodiment  500  are highly dependent upon the nature of cable  504  and conductors  110 . An armored commercial cable  504  typically has a diameter of 0.933 inches, and commercially available conductors  110  typically have a diameter of 0.260 inches. Since the diameter of cable  504  is substantially equal to the diameter of cable  104  plus adhesive  108 , then the dimensions of jacket  102  discussed above are equally applicable to jacket  502 .  
         [0046]     The manufacture of embodiment  500  is similar to embodiment  100 . The steps of applying adhesive and heating are replaced with a step of removing the “tar and jute” outer coating of cable  504 . The remainder of the manufacturing process is the same.  
         [0047]     It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to certain embodiments, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.