Patent Publication Number: US-2011075983-A1

Title: Telecommunications cable inlet device

Description:
FIELD OF THE INVENTION 
     The present invention relates to an inlet device for inserting a plurality of telecommunication cables containing optical fibers, copper wires or micro-coax cables into a telecommunication enclosure, e.g. into a terminal closure, pre-stubbed terminal, optical network terminal or other junction box. 
     BACKGROUND OF THE INVENTION 
     Telecommunication cables are ubiquitous and used for distributing data across vast networks. The majority of cables are electrically conductive cables (typically copper), although the use of optical fiber cables is growing rapidly in telecommunication networks as larger and larger amounts of data are transmitted. 
     As telecommunication cables are routed across data networks, it is necessary to periodically open the cable so that one or more telecommunication lines therein may be spliced, thereby allowing data to be distributed to other cables or “branches” of the telecommunication network. At each point where a telecommunication cable is opened, it is necessary to provide a telecommunication enclosure to protect the exposed interior of the cable. The cable branches may be further distributed until the network reaches individual homes, businesses, offices, and so on. 
     Many conventional telecommunication enclosures utilize either a mastic or rubber grommets for introducing cables into the enclosure. Some mastic and grommet assemblies can accommodate more than one cable. Alternatively, inlet devices that may be mounted onto the cable prior to installation of the cable in a port of a telecommunication enclosure are also known. However, these inlet devices typically accommodate only one cable per port in the enclosure. Conventional inlet devices are described in U.S. Pat. No. 6,487,344 and U.S. Patent Publication No. 2009/0060421 A1 which can be inserted into a port in the wall of a telecommunication enclosure. 
     SUMMARY OF THE INVENTION 
     An exemplary inlet device is described herein for inserting a plurality telecommunication cables into a port of a telecommunication enclosure. The inlet device includes a housing, a retention device and a compression member. The housing has a first end and a second end, wherein the housing includes a compressible portion at the second end of the housing and the retention device may be secured to the first end of the housing. The compression member may be fitted over the compressible portion at the second end of the housing. The cable retention device includes a rack to discretely hold a plurality of telecommunication cables. The cables may be further secured in the rack of the cable retention device by one or more clamping devices. 
     In an alternative aspect of an exemplary inlet device, inlet device includes a housing, a retention device, a compression member and a pressure wedge. The housing has a first end and a second end, wherein the housing includes a compressible portion at the second end of the housing and the retention device may be secured to the first end of the housing. The compression member may be fitted over the compressible portion at the second end of the housing. The cable retention device includes a rack to discretely hold a plurality of telecommunication cables. The pressure wedge may be inserted into the rack to further lock the plurality of communication cables into the cable retention device. A clamping member or hook may be used to lock the pressure wedge into the rack of the cable retention device. 
     The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and the detailed description that follow more particularly exemplify these embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be further described with reference to the accompanying drawings, wherein: 
         FIG. 1A  shows an exploded view of an exemplary inlet device according to an aspect of the present invention; 
         FIG. 1B  shows an partially assembled view of the inlet device of  FIG. 1A ; 
         FIG. 1C  shows an exploded view of the housing and retention device of  FIG. 1A ; 
         FIGS. 2A-F  show several alternative aspects of an exemplary retention device; 
         FIGS. 3A-G  show several aspects of an alternative retention device including a pressure wedge according to the present invention; 
         FIGS. 4A and 4B  show another alternative retention device including a pressure wedge according to an aspect of the present invention 
         FIGS. 5A and 5B  show two embodiments of exemplary internal sealing members insertable in an exemplary inlet device according to an aspect of the present invention; and 
         FIG. 6  shows an isometric view of an alternative housing according to an aspect of the present invention. 
     
    
    
     While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE DRAWINGS 
     In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings, which illustrate specific embodiments in which the invention may be practiced. The illustrated embodiments are not intended to be exhaustive of all embodiments according to the invention. It is to be understood that other embodiments may be utilized and that structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. 
     Exemplary embodiments herein provide an inlet device for the insertion of a plurality of telecommunication cables into a telecommunication enclosure, especially a plurality of telecommunication drop cables through a single port of a telecommunication enclosure. The drop cables may be optical fiber cables, a small pair count copper cables or micro-coax cables. Particular advantages of the design of the present inlet device include a low cost, field installable inlet device that provides an environmental seal around a plurality of drop cables. The inventive inlet device has fewer parts than some conventional inlet devices which makes it straight forward to install in the field. 
     The exemplary inlet device may be fitted to a communication cable and inserted into a port in a telecommunication enclosure to secure the telecommunication cable in the port. Depending on the communication network architecture, the telecommunication enclosure may be a buried closure, an aerial closure or terminal, a fiber distribution hub or an optical network terminal in the outside plant or a wall mount communication box, fiber distribution hub, a wall mount patch panel, or an optical network terminal in premise applications. 
     In one exemplary embodiment, the telecommunication cable is a fiber optic cable such as a fiber reinforced plastics (FRP) drop cable available from Shenzhen SDG information Co., Ltd. (Shenzhen Guangdong, China). Fiber optic cable typically includes a semi-rigid outer sheath surrounding at least one optical fiber and at least one strength member. The optical fibers may be enclosed in one or more loose buffer tubes or may be provided as one or more optical fiber ribbon cables. Each optical fiber has a polymeric coating that surrounds and protects the glass fiber. Additional examples of exemplary optical fiber cables include ResiLink ADF™ All-Dielectric Flat Drop Cable available from Pirelli Cables and Systems (Columbia, N.C.) or EZ DROP cable from Draka (Claremont, N.C.), and Mini DP Flat Drop Cable available from OFS (Northcross, Ga.). The strength members may be either semi-rigid rods or a collection of loose fibers e.g. made of aramid fibers. 
     Alternatively, the telecommunication cable may be a low wire count copper cable having a semi-rigid sheath surrounding a plurality of paired copper wires or a copper micro-coax cable. 
     Referring to  FIGS. 1A-1C , an exemplary inlet device  100  includes a housing  110  having a first end  111  and a second end  112 , an internal sealing member  140  shaped to be received within the second end  112  of the housing, and a compression member attachable to the second end  112  of the housing. The compression member may be a clamping nut  150  or other device capable of applying a radial force to the second end  112  of the inlet device housing  110 . The inlet device  100  may be formed of plastic by conventional methods, for example by injection molding. 
     The housing  110  may be generally cylindrical in shape and includes an interior passageway  113  that extends along the length of the housing from the first end  111  to the second end  112  of the housing. The housing includes a passage entry  113   a  at the first end  111  of the interior passageway  113  and a passage exit  113   b  at the second end  112  of the interior passageway  113  that may be configured to accommodate certain categories of telecommunication cables including single fiber drop cables, multi-fiber cables, copper communication cables or micro-coax cables. 
     The first end of the housing will reside inside the telecommunication enclosure when the inlet device has been fully inserted into a port of a telecommunication enclosure. A locking fork  160  ( FIG. 1A ) can be inserted into receiving channel  119  on housing  110  of inlet device  100  to secure the inlet device in the port of the telecommunication enclosure. The second end of the housing may be located within the port of the telecommunication enclosure when the inlet device has been fully inserted into a port of a telecommunication enclosure. Alternatively, the second end of the tubular body may extend completely through the port of the telecommunication enclosure. 
     A groove  116  may be located between the first end  111  and the second end  112  of housing  110  to receive an external sealing member  145  such as an o-ring. This external sealing member  145  can provide an environmental seal between the inlet device  100  and a port of a telecommunication enclosure when the inlet device is fully seated therein. 
     The housing  110  can have an external threaded portion  118  located between groove  116  and the second end  112  of the housing  110 . The external threaded portion  118  cooperates with a corresponding internal threaded portion  158  of a compression member (e.g. clamping nut  150 ) to cause a compressible portion  115  of the housing  110  to be constricted around the internal sealing member to hold the cables installed therein. 
     The compressible portion  115  is formed at the second end  112  of the housing  110 . The compressible portion  115  may be reduced in size (diameter) when an external radial force is exerted on it such as by application of the clamping nut  150 . The compressible portion  115  may include a plurality of spaced apart flexible fingers  115   a  which surround the passage exit  113   b . The fingers  115   a  may be squeezed together the clamping nut  150  is attached to the second end of the housing  110 . An optional internal sealing member  140  may be fitted into the interior passageway  113  in the compressible portion  115  of the housing  110  to improve the sealing capability of the inlet device  100  around a plurality of telecommunication cables as may be needed in buried or other subterranean telecommunication enclosure installations. The telecommunication cables  50  ( FIG. 2C ) pass through the internal sealing member  140  when the cable is installed into the inlet device  100 . The tightening of the clamping nut  150  over the compressible portion  115  of the housing  110  compresses the internal sealing member  140  around the communication cables  50 . In some applications such as in premise installations, a lesser degree of environmental protection is required and the internal sealing member  140  may be replaced by a sealing member having a single opening. In this case, all the incoming cables will pass through the single opening of the sealing member and this sealing member may be compressed by the compressible portion of the housing of an exemplary inlet device. 
     The cable clamping nut  150 , shown in  FIG. 1A , has an interior chamber  153  extending between the first side  151  and a second side  152  of the clamping nut. The interior chamber  153  has a first opening  154  at the first side  151  to accept the second end  112  of housing  110 . The interior chamber  153  has a smaller second opening (not shown) at the second side  152  of the clamping nut  150  to accommodate the passage of a telecommunication cable therethrough. The interior chamber  153  has an internal threaded portion  158  that corresponds to and is engagable with the external threaded portion  118  on the housing  110  to allow the cable clamping nut  150  to be secured to the housing. 
     In an exemplary embodiment, clamping nut  150  can have a gripping surface  157  on the external surface of the cable clamping nut that corresponds to the position of the internal threaded portion  158 . The external gripping surface  157  may be a hexagonally shaped cross-section as shown in  FIG. 1A  to facilitate gripping of the cable securing device with a tool or by hand. The gripping surface region may have other geometric configurations such as a circular cross-section, a rectangular cross-section or other polygonal cross-section. Additionally, the gripping surface may be textured (e.g. a ridged or cross-hatched texture) to further facilitate gripping of the cable securing device. 
     Clamping nut  150  includes a retaining clamp  159  disposed on the second side  152  of clamping nut  150  to securely hold one or more telecommunication cables. Two longitudinal side tabs  159   a  project from the second side  152  of clamping nut  150 . Two halves  159   b  of retaining clamp  159  may be secured to the longitudinal side tabs by conventional mechanical fasteners  159   d  such as by screws or rivets. The interior surface  159   c  of the two clamp halves may be concave and have ridges or barbs to bite into the sheath of the telecommunication cables to further securely grip the telecommunications cable when it is installed into an exemplary inlet device. In an alternative embodiment, one of the halves of the retaining clamp may be integrally formed with the longitudinal side tabs to reduce the number of parts required. Alternative forms of cable clamping nuts are described in U.S. Patent Application No. 61/043,652, which is incorporated by reference herein, in its entirety. 
     A cable retention device  120  may be secured to the first end  111  of the housing  110  such as by the insertion of tongue  121  on the cable retention device  120  into the passage entry  113   a  of the housing. Tongue  121  may be positioned below guides  113   c  disposed on the wall of the interior passageway  113  of housing  110 . In an exemplary embodiment, guides  113   c  may be in the form of a pair of longitudinal ridges located on opposing sides of the interior passageway  113  and that extend along a length of the interior passageway. Alternatively, the guides may be in the form of a series of spaced apart bumps located on opposing sides of the interior passageway and that extend along a length of the interior passageway. The guides  113   c  control the vertical position of the cable retention device  120  in the housing  110 . The cable retention device  120  may be slid into the housing  110  until positioning bump  117   a  on extension  117  of housing engages with a depression or hole  122  on tongue  121  of the cable retention device to fix the horizontal position of the cable retention device  120  in the housing. When fully seated within the housing  110 , the ribs  121   a  disposed on tongue  121  interact with guides  113   c  to hold the cable retention device  120  in place. 
     Referring to  FIGS. 2A-D , cable retention device  120  includes a rack  122  for securing a plurality of telecommunication cables  50  to the inlet device. In an exemplary embodiment, a plurality of fiber optic drop cables, such as FRP drop cables may be fitted into a corresponding number of compartments  122   a  within the rack  122  of cable retention device  120 . Each compartment  122   a  may be separated from an adjacent compartment next to it by a central support  122   d  and from the compartment above or below it by a shelf  122   b  that extend from the central support  122   d . The central support  122   d  attaches to a base  122   e  on the bottom end thereof and a top shelf  122   c  at the top of the central support opposite the base  122   e . Each shelf  122   b  can have a plurality of ridges  222   f  ( FIG. 3C ) or teeth  122   f  located on one or both surfaces of the shelf. The teeth  122   f  can engage with the outer sheath of the telecommunication cable to hold it firmly within a given compartment against an axial load placed on the cable. 
     Additionally, the retention device  120  may have at least one clamping member to assist in retaining the cables within the compartments of rack  122 .  FIG. 2A-2D  show a retention device having two clamping members  125  which are hingedly attached to the base  122   e  of rack  122  through a hinge pin  122   g  that is integrally formed with the base and at least one C-shaped holder  125   c  formed on one edge of each clamping members. In the exemplary embodiment shown in  FIGS. 2A and 2B , each clamping member has a resilient latch  125   a  extending from an edge of the clamping member opposite the C-shaped holder  125   c . The latch  125   a  engages with a catch  122   h  on the top of the top shelf  122   c  of rack  122 . 
       FIG. 2C  shows the installation of telecommunication cables  50  into the cable retention device  120 . The telecommunication cable  50  is placed into compartments  122   a . Once the desired number of telecommunication cables has been installed on one side of the rack, the clamping member on that side of the rack may be closed. Then the remaining cables may be placed in the other side of the rack and that clamping member closed when they are in place. Advantageously, the clamping members may assist in the final positioning of the telecommunication cables within compartments  122   a  by pushing the cables fully into each compartment. In one exemplary embodiment, the clamping members may have a ridge or plurality bumps (not shown) extending longitudinally along the clamping member and aligned with each compartment to assist in pushing the telecommunication cables into the compartments.  FIG. 2D  shows six telecommunication cables  50  installed into the cable retention device  120 .  FIG. 2E  is a cross-section of an exemplary cable retention device  120  showing the proper positioning of the telecommunication cables  50  installed in compartments  122   a  of rack  122 . 
       FIG. 2F  shows an alternative embodiment of a cable retention device  120 ′ having a different hinging mechanism attaching the clamping members  125   f ′ to rack  122 ′. The clamping members  125 ′ have a rotation shaft  126  extending along an edge of the clamping member opposite the side having latch  125   a . The rotation shaft may be snapped into hinge receptors  127  which are integrally formed with the base  122   e ′ of rack  122 ′. Once attached to the rack  122 ′, the clamping member pivots in a manner similar to that described previously. In an alternative embodiment, a single U-shaped clamping member may be hingedly attached to one side of the base of the rack. This U-shaped clamping member may be closed after the desired number of communication cables have been installed into the rack by swinging the free leg of the clamping member over the rack and clipping it to the other side of the base opposite the hinge. In yet another alternative embodiment of the retention device, the clamping members may be separate clips having a latch along two opposite sides that encage with catches located on the top shelf and the base of the rack. Alternatively, a single U-shaped clamping member may be fitted over the rack and secured by latches to the base of the rack by clips or latches. 
     Referring to  FIGS. 3A-C , cable retention device  220  includes a rack  222  for securing a plurality of telecommunication cables to the inlet device and a tongue  221  extending from the backside of the rack  222  to secure the retention device  220  in to the housing of an inlet device as described previously. Retention device  220  has a base  222   e  and a crown  222   c  with two side walls  222   d  that extend generally perpendicular from the base  222   e  to the crown  222   c . In an exemplary embodiment, a plurality of fiber optic drop cables, such as FRP drop cables may be fitted into a corresponding number of compartments  222   a  within the rack  222  of retention device  220 . In the embodiment shown in  FIGS. 3A and 3B , there are three compartments  222   a  adjacent to the base  222   e  and three more compartments  222   a  adjacent to the crown  222   c . Each compartment  222   a  may be separated from an adjacent compartment next to it by a partition  222   b . Each partition  222   b  can have a plurality of ridges or teeth  222   f  located on one or both surfaces of each partition. The teeth  222   f  can engage with the outer sheath of the telecommunication cable to hold it firmly within a given compartment against an axial load placed on the cable. 
     Additionally, the retention device may have a pressure wedge  228  to assist in retaining the cables within their respective compartments. Pressure wedge  228  can be inserted into the front end of the rack  222  between the compartments  222   a  adjacent to the crown  222   c  and the compartments  222   a  adjacent to the base  222   e  after the telecommunication cables have been inserted into rack  222 . The pressure wedge  228  is inserted until wings  228   a  meet the stops  222   g  on rack  222 . The pressure wedge  228  has a tapered front end to facilitate insertion of the pressure wedge into rack  222 .  FIGS. 3A and 3B  show a pair of clamping members  225  that lock the pressure wedge  228  in rack  222  when the latches  225   a  on each clamping member engage with cantilevered hooks  228   b  on the pressure wedge. 
       FIGS. 3B and 3C  show a clamping member  225  and the rack  222  of retention device  220  of  FIG. 3A , respectively. The inside surface of clamping member  225  is shown in  FIG. 3B . The clamping member  225  has a recess  225   b  to accommodate the wings  228   a  of the pressure wedge  228 , shown in  FIG. 3A , when the clamping members are closed to secure the pressure wedge in the rack of retention device. The clamping member  225  may be pivotally attached to rack  222  by inserting bosses  225   c  on the clamping members into cavities  222   h  in the rack. 
     The telecommunication cables may be inserted through rack  222  and positioned in compartments  222   a .  FIG. 3D  shows a cross-section of rack  222  including telecommunication cables  50  positioned in compartments  222   a . Once the desired number of telecommunication cables have been installed in the rack, the pressure wedge  228  is inserted into the front end of the rack  222  in an insertion direction  228   d  between the compartments  222   a  adjacent to the crown  222   c  and the compartments  222   a  adjacent to the base  222   e  as shown in  FIG. 3E .  FIG. 3F  shows the closing of the clamping members in a direction  225   d  to secure the pressure wedge in rack  222 . The latch  225   a  on the clamping member  225  engages with the cantilevered hook  228   b  on the pressure wedge to lock the wedge in rack  222 .  FIG. 3G  shows an exemplary embodiment of an assembled retention device  220  having six telecommunication cables  50  installed therein. While the embodiment shown in  FIG. 3G  shows a retention device with six cables, the retention device may be designed to hold any number of cables from one up to the number of compartments in the rack of the retention device. In addition, the retention device may be designed with either more or less compartments than are shown in the figures depending on the size and shape of the cables to be held and the size of the port in a telecommunication enclosure into which the inlet device is to be installed. Thus, the embodiments in the figures should not be construed as limiting. 
       FIGS. 4A and 4B  show an alternative embodiment of a cable retention device  220 ′ having a pressure wedge  228 ′. Pressure wedge  228 ′ has a pair of hooks  228   b ′ formed at the tapered front end  228   c  of the pressure wedge. The pressure wedge  228 ′ can be inserted into the front side of rack  222 ′ in a direction  228   d ′ until the wings  228   a ′ of the pressure wedge contact the stops  222   g ′ of rack  222 ′. The hooks  228   b ′ can engage with the side walls  222   d ′ of retention device  220 ′ to secure pressure wedge  228 ′ into the rack  222 ′. To release the pressure wedge  228 ′, the hooks may be pressed inwards and the pressure wedge may be extracted from rack  222 ′ by pulling it in a direction opposite the insertion direction  228   d′.    
       FIGS. 5A and 5B  show two exemplary embodiments of internal sealing members  140   a ,  140   b  which are insertable in the second end of the housing in the exemplary inlet device described herein.  FIG. 5A  shows an internal sealing member  140 A capable of accommodating six FRP drop cables and  FIG. 5B  shows and internal sealing member  140   b  capable of accommodating four FRP drop cables. 
     The details of an exemplary internal sealing member  140   a  will be described with respect to  FIG. 5A . Internal sealing member  140   a  has six openings  144  passing from a first end  141  to a second end  142  to accommodate insertion of up to six drop cables (not shown) therethrough. The internal sealing member  140   a  can have a first diameter at the first end  141  of the internal sealing member, a second diameter at the second end  142  of the internal sealing member, and a step transition  143  between the first and second ends. The first diameter can be smaller than the second diameter, such that the first end  141  of the internal sealing member may be inserted into the interior passage way of the inlet device&#39;s housing. The larger second diameter may be accommodated within the compressible portion of the housing. The step transition  143  can prevent the internal sealing member from slipping too far inside of the housing when the clamping nut is applied to the second end of the housing to compress the compressible portion of the housing around the internal sealing member  140   a . The size and shape of the openings may be altered to accommodate other types of optical fiber drop cables such as flat drop cables and round drop cables. In one exemplary embodiment, it may be desirable to install an exemplary inlet device with an internal sealing member having some number of opening running through the internal sealing member, but install some number of cables that is less than the number of openings in the internal sealing member. In this case a blank pug (not shown) can be inserted into any of the openings in the internal sealing member not filled with a telecommunication cable. This allows for the addition of adding additional drop cables when additional service connections are needed while maintaining the environmental sealing of the inlet device. In an alternative, the internal sealing member may be formed having a thin web (not show) of material blocking the openings at one end of the sealing member. In this embodiment, the craftsman may puncture the thin web in the openings in which cables are to be installed. If fewer cables are inserted through the internal sealing member than the number of available openings, the thin web will ensure the environmental sealing of the inlet device. 
       FIG. 6  shows an alternative embodiment of a housing  310  having a first end  311  and a second end  312 . The housing  310  may be generally cylindrical in shape and includes an interior passageway  313  that extends along the length of the housing  310  from the first end  311  to the second end  312  of the housing. Housing  310  includes a passage exit  313   b  at the second end  312  of the interior passageway  313  that may be configured to accommodate certain categories of telecommunication cables including single fiber drop cables and multi-fiber cables and a passage entry (not shown) to accommodate a retention device as described previously. 
     Housing  310  can have a securing zone  330  adjacent to the first end  311  of the housing. The securing zone  330  may include a pair of locking elements  332  which protrude from opposite sides of the housing  310 . In an exemplary housing  310 , the locking elements  332  may have a deformable cantilever structure which can flex when depressed to allow the inlet device to be removed from a close fitting port of a telecommunication enclosure. This housing configuration is described more fully in U.S. Patent Application No. 61/043,652, which is incorporated by reference herein, in its entirety. 
     The inlet device embodiments described above provide a simple and user-friendly design thereby greatly facilitating the installation of the last leg of the FTTH network to the end user. 
     Various modifications including extending the use of the inlet device to applications with copper telecommunication cables or copper coax cables, equivalent processes, as well as numerous structures to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the present specification.