Abstract:
A new adapter and method for providing strain relief to and creating a liquid tight seal around a cable including a first nut with a tubular extension, the tubular extension having a plurality of deflectable arms, each of which are radically converged and constricted about a cable under a compression force caused by the tightening of a second nut having a tapered region formed in an inner nut channel.

Description:
FIELD OF THE INVENTION 
     This invention relates to an adapter for providing strain relief to jacketed cables and for preventing moisture or water from damaging the cables. In particular, the invention is directed to a strain relief adapter connectable to the end of a cable conduit, such as a pipe, for securing jacketed cables of variable diameters carrying tip ring wire pairs to telephone junction boxes for distribution to telephone equipment. Further, the strain relief adapter is provided with a sleeve for sealing the adapter from moisture or water. 
     BACKGROUND OF THE INVENTION 
     Telephone lines, which are carried by electrical conductors known as tip ring wire pairs, are generally aggregated at a particular point in a building prior to being distributed and connected to various types of telephone equipment, such as, for example, telephones, fax machines, modems etc. As the tip ring pairs enter the building as part of a multi-conductor cable, the individual tip ring wire pairs must first be broken out from the cable into individual wire pairs. This is normally accomplished in a junction box known as, for example, a building entrance protector (BEP), or network interface unit (NIU). 
     The multi-conductor cables are generally enclosed in stiff insulation jackets having variable diameters depending upon the particular application. Because these multi-conductor cables carry the tip ring wire pairs that will be connected to various types of telephone equipment, it is necessary to provide strain relief to the cable to insure that the tip ring wire pairs do not become disconnected or loose. Loose or disconnected wires in a junction box can cause serious malfunctions in telephone, computer, or network service requiring costly repair and maintenance service. Moreover, it is desirable to provide a liquid tight seal to prevent moisture or water from invading the adapter and damaging the cable or wires within. 
     Thus, there is a need for an adapter capable of securing multi-conductor cables of variable diameters and providing a liquid tight seal. 
     SUMMARY OF THE INVENTION 
     The present invention is directed at overcoming shortcomings in the prior art. The present invention comprises a first nut connectable to an end of a cable conduit such that the cable carried within the conduit can be fed into and through the adapter. A tubular extension extends longitudinally from the base and has a compressible portion for constricting around and, thereby, securing a cable. A second nut is mountable over the tubular extension and has an inner channel provided with a tapered region for constricting the compressible portion of the tubular extension. 
     The operation of mounting the second nut over the tubular extension causes the tapered region of the second nut to exert a compression force on the compressible portion, which deflects the compressible portion inward. In use, the first nut is connected to a conduit carrying a cable and the cable to be strain relieved is passed through the tubular extension. The second nut is then mounted to the tubular extension to provide strain relief. As the compressible portion is deflected inward an inner surface of the compressible portion contacts the cable and grippingly secures the cable in place. Because the compressible portion can be gradually compressed by the second nut to a desired compression, a range of variable diameter cables can be secured by the present invention. Thus, the need to use cable fastening devices constructed for specific cable diameters is eliminated, thereby improving efficiency and reliability in cable connections. 
     In a preferred embodiment, the compression portion is comprised of a plurality of deflectable arms having gripping ends. Under a compression force, the gripping ends radially converge and secure the cable. 
     A second preferred embodiment further comprises a sleeve that is inserted into the tubular extension for providing a liquid tight seal. The sleeve conforms to the inner wall of the tubular extension and is tightly compressed against the cable when the second nut is mounted. Thus, the adapter prevents moisture or water from damaging the cable or the wires within. 
     Other objects and features of the present invention will become apparent from the following detailed description, considered in conjunction with the accompanying drawing figures. It is to be understood, however, that the drawings, which are not to scale, are designed solely for the purpose of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the figures, which are not to scale, and which are merely illustrative, and wherein like reference numerals depict like elements throughout several views: 
     FIG. 1 is a side view of the first nut and tubular extension of a strain relief adapter in accordance with the present invention; 
     FIG. 2 is a top view of the first nut and tubular extension of the adapter in FIG. 1; 
     FIG. 3 is side view of the second nut of the adapter in FIG. 1; 
     FIG. 4 is a side view of the adapter of FIG. 1 engaged with a conduit carrying a cable; 
     FIG. 5 is an isometric view of the adapter in FIG. 1, wherein the compressible portion is in an uncompressed state; 
     FIG. 6 is an isometric view of the adapter in FIG. 1, wherein the compressible portion is in a fully compressed state; 
     FIG. 7 is a side view of the adapter of FIG. 1, wherein a sleeve is shown; and 
     FIG. 8 is a top view of the adapter of FIG. 1, wherein a sleeve is shown. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 to  8 , there is shown a strain relief adapter  1  constructed in accordance with the present invention. Adapter  1 , which is fully depicted in FIGS. 5 and 6, comprises a first nut  10  constructed to be connectable to the end of a cable conduit, as shown in FIG. 4. A tubular extension  20  longitudinally extends from a second open end  16  of first nut  10 . Tubular extension  20 , preferably, has a male screw thread  26  on outer surface  24  and a compressible portion  28  for grippingly securing a cable. 
     Second nut  50 , which is constructed to cause compressible portion  28  to grip a cable, has a female screw thread  58  formed on at least part of inner channel  56  located nearest first nut end  52 . Female screw thread  58  is constructed to threadingly engage male screw thread  26  of tubular extension  20 . Inner channel  56  is further provided with a tapered region  60  sloping inwardly towards second end  54 . One skilled in the art will recognize that the present invention is capable of being utilized in any number of applications, such as, by way of non-limiting example, securing multi-conductor cable in BEPs or NIUs. 
     In a second embodiment, described further below, sleeve  80  is constructed to form fit to inner arm surfaces  35  of tubular extension  20 , thereby further defining channel  40  of adapter  1 . As will be described further, sleeve  80  creates a substantially liquid tight seal upon contact with a secured cable. 
     With reference to FIG. 1, there is shown a preferred embodiment of first nut  10  for use with the present invention. First nut  10  is preferably a hexagonal nut, although any type of nut generally known in the art may be utilized. First nut  10  is constructed to be connectable to the end of a cable conduit, such as, for example, a threaded pipe constructed to carry telephone or electrical wires (not shown). In a preferred embodiment, as depicted in FIG. 4, first nut  10  is provided with a first open end  14  into which the conduit or threaded pipe is matingly engaged with an internal female screw thread  12  formed on a portion of channel  18  nearest first open end  14 . The cable carried within the engaged conduit is then fed into and through first nut channel  18  past second open end  16  into the compressible portion  28  of tubular extension  20 . One skilled in the art will recognize, however, that first nut  10  may be connected to a conduit in any manner known in the art, including but not limited to, snap-fitting, friction fitting, adhesive, and the like. 
     With further reference to FIG. 1, first nut  10  is provided with tubular extension  20 , which longitudinally extends from second open end  16  of first nut  10 . Tubular extension  20  preferably has a male screw thread  26  on outer surface  24 . Male screw thread  26  is constructed to matingly engage internal female screw thread  58  of second nut  50 , as discussed further below. One skilled in the art will recognize, however, that mounting second nut  50  over tubular extension  20  via the mating engagement of threaded regions is but one manner in which the mounting may be accomplished. Second nut  50  may, by way of non-limiting example, be snap-fit, friction fit, or fit in any other way to achieve the compression of compressible portion  28  and the securement of second nut  50  over tubular extension  20 . 
     Tubular extension  20  preferably is formed of a durable, flexible material, such as plastic. Tubular extension  20  is provided with compressible portion  28  for securing a cable or conduit. In a preferred embodiment, compressible portion  28  comprises a plurality of deflectable arms  30  extending from tubular extension  20 . Each arm  30  is tapered such that each arm is wider at base  32  and thinner at gripping end  34 . The taper results in ends  34  being freely spaced. 
     With further reference to FIG. 2, arms  30  are preferably arranged and equidistant from one another to ensure even gripping forces. Inner arm surfaces  35  of arms  34  collectively define gripping channel  40 , which determines the boundaries of the relative diameter of compressible portion  28  in a compressed and uncompressed state. Because gripping ends  34  are freely spaced gripping ends  34  are free to deflected inward, causing compressible portion  28  to constrict around and grip a cable. Although not depicted in the drawings, one skilled in the art will recognize that gripping ends  34  may, for example, be provided with non-flat surfaces, such as grooved or notched surfaces to increase the gripping force exerted on a cable. 
     With reference to FIG. 3, there is shown a preferred embodiment of second nut  50  for use with the present invention. Second nut  50  is preferably a hexagonal nut, although any type of nut generally known in the art may be utilized. Second nut  50  preferably has a first open end  52  allowing second  50  to be mounted over tubular extension  20  and a generally cylindrically-shaped inner channel  56 . As stated above, second nut  50  may be fit over tubular extension  20  in any manner that achieves compression and securement. Inner channel  56  is provided with an internal female screw thread  58  nearest to first open end  52  for engagement with the corresponding male screw thread  26  of tubular extension  20 . Inner channel  56  is further provided with a tapered region  60  nearest to second end  54  and adjacent to female screw thread  58 . Tapered region  60  slopes inwardly towards second end  54 . The particular angle of slope of tapered region  60  is a matter of design choice and is subject to the specific application for which the present invention is utilized. 
     With reference now to FIG. 4, there is shown strain relief adapter  1  connected to conduit  200 . Conduit  200  carries within a cable  210  which in turn holds a plurality of wires. As previously stated, one skilled in the art will recognize that first nut  10  may be connected to conduit  200  in any manner known in the art, including but not limited to, snap-fitting, friction fitting, adhesive, and the like. Further, conduit  200  and strain relief adapter  1  may be integrally formed. In use, upon connection of first nut  10  to an end  202  of conduit  200  through the mating engagement of screw thread  12  of first nut  10  and screw thread  204  of conduit  200 , cable  210  can be fed into tubular extension  20  for securement. 
     Conduit  200  is an exemplary embodiment, since adapter  1  can be mounted to any surface formed to receive it. Thus, adapter  1  can be mounted or formed on conduits, enclosures, wire panels, distribution frames, or any other surface portion of a structure adapter to receive or pass cables, wires or other elongate members. 
     With reference now to FIGS. 5 and 6, there is shown second nut  50  mounted onto tubular extension  20  through the mating engagement of female screw thread  58  of second nut  50  with male screw thread  26  of tubular extension  20 . As depicted in FIG. 4, second nut  50  is in a first position wherein the plurality of deflectable arms  30  of compressible portion  28  are in an uncompressed state. In an uncompressed state, channel  40 , which is defined by the plurality of deflectable arms  30 , is at its maximum diameter. In this state, a cable or conduit, as shown in FIG. 4, may be slid into and through channel  40 , although it is not necessary for channel  40  to be at its maximum diameter for a cable to be fed into channel  44 . As second nut  50  is tightened, gripping ends  34  contact tapered region  60  forcing gripping ends  34  to converge radially inward. This inward deflection results in the gradual decrease in the diameter of channel  40 . As depicted in FIG. 5, when second nut  50  is fully tightened, deflectable arms  30  of compressible portion  28  are fully constricted and the diameter of channel  40  is at a minimum. The gradual convergence of gripping ends  34  and the reduction in diameter of channel  40  causes gripping ends  34  to make gripping contact with the inserted cable or conduit, thereby securing the cable or conduit. 
     Because the tightening of second nut  50  causes compressible portion  28  to gradually compress until reaching a fully compressed state, a multitude of cable diameters can be secured by adapter  1 . The diameters of cables used with the present invention can range from the maximum diameter of channel  40  in an uncompressed state to the minimum diameter of channel  40  in a fully compressed state. One skilled in the art will recognize, however, that the respective compressed and uncompressed diameters of channel  40  are a matter of design choice and may be varied to accommodate difference ranges of cable diameters depending upon the particular application. 
     With reference now to FIGS. 7 and 8, there is shown a second embodiment of the present invention wherein sleeve  80  is positioned inside tubular extension  20  for creating a substantially liquid tight seal. Sleeve  80  is preferably substantially cylindrical in shape and constructed of a flexible rubber-type material best suited to sealingly mold to a cable or conduit. One skilled in the art will recognize that sleeve  80  may be constructed from any material known in the art capable of creating a liquid tight seal around a cable or conduit. Outer surface  82  of sleeve  80  conforms to an inner arm surfaces  35  and further defines channel  40 , such that sealing portion  84  of sleeve  80  mirrors the minimization of channel  40  under a compression force. 
     In use, the inward convergence of deflectable arms  30  forces sealing portion  84  to contact the cable or conduit. The contact between sleeve  80  and the outer surface of the cable or conduit creates a substantially liquid tight seal for preventing moisture or water from penetrating adapter  1 . The seal ensures that the wires carried within the cable are not damaged. Further, the friction created between sealing portion  84  of sleeve  80  and the cable provides an additional measure of strain relief. 
     With further reference to FIG. 7, a preferred embodiment is shown wherein arms  30  are provided with a notch  36  and sealing portion  84  of sleeve  80  is provided with lip  86 . Lip  86  meshes with notch  36  to prevent sleeve  80  from becoming dislodged. Furthermore, the meshing action of lip  86  and notch  36  ensures that, as arms  30  are deflected inward, sealing portion  84  is constricted around the cable. 
     Further, one skilled in the art will recognize that strain relief device  1  is not limited to the uses described herein, but may be used in applications pertaining to any field where there is a need to secure cables or other elongate members. 
     Thus, while there have been shown and described and pointed out fundamental novel features of the invention as applied to preferred embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of the disclosed invention may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.