Abstract:
A seal is provided to seal the area between a cable containing optic fibers and the terminal end of a conduit through which the cable runs. The seal consists of a resilient gasket and a supporting structure and a cam. The seal assembly, encompassing the cable, is inserted into the terminal end of a conduit that houses the cable. Actuation of a cam compresses a gasket into sealing contact with the cable and with the conduit, thereby sealing the terminal end of the conduit from entry of contaminants.

Description:
BACKGROUND—FIELD OF THE IVENTION 
     This invention relates to sealing the area between a terminated conduit and a cable that egresses therefrom. 
     BACKGROUND—PRIOR ART 
     Fiber optic cables have become a preferred transmission system for telecommunication and data communication. A cable can contain many strands of optic fibers. These cables are generally installed underground inside a conduit. The conduit and the cable that runs through it are often laid in trenches and can extend for long distances. For purposes of maintenance, upgrading, and connection to the fiber optics, underground vaults are installed strategically along the path of the conduit and cable. Many cables and conduits may terminate or run through these vaults or other similar compartments. When a conduit terminates, but the cable continues its run, it is desirable to provide a seal between the cable and the conduit at the termination of the conduit. This seal prevents contaminants from entering the space between the cable and the conduit and thereby avoids possible deterioration of the fiber optic cable and its contents. 
     Schemes to effect this seal are easily provided if both the conduit and cable terminate in close proximity of each other. In this case, the seal is formed by a gasket and supporting structure. The gasket and its supports can slide axially over the cable and into the conduit. This is not the case if the end of the cable is not accessible. In this case the gasket and its supports must be split or halved in order to surround the cable. Such a seal is described in U.S. Pat. No. 4,842,364. The device described requires intricate fabrication techniques that utilize split threaded devices used for producing compression force on a gasket, thus causing the gasket to expand. The threaded nut is made in two halves and must be assembled around the cable. During fabrication of this nut, significant effort must be given to the correct timing of the threads so that when assembled the mating halves will produce a continuous thread. Assembly of the split halves can be difficult. In this prior art, the majority of the assembly of the seal occurs at the installation site, in the confines of an underground vault, which is difficult because the pieces are small and intricate. If the threaded parts are made of plastic, the tooling to produce these parts is intricate, complicated, and expensive. The amount of compression of the gasket in this and other prior art is dependent on how tightly threaded members are torqued. Since this torque is uncontrolled, large forces may be transmitted which may damage the conduit and/or cable. Conversely, if too little torque is applied, the gasket may not seal as intended. Some prior art use metal fasteners as part of the scheme to compress a gasket. Metal may corrode after time. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is the object of this invention to provide a simple, cost effective means to seal the area around a cable and the conduit in which the cable resides. The advantages are: 
     (a) extreme ease of installation 
     (b) low cost 
     (c) complete assembly ease prior to installation 
     (d) controlled force that is transmitted to the cable and conduit 
     (e) excellent sealing between cable and conduit 
     (f) resistance to chemicals in its environment 
     (g) inherent corrosion resistance 
     Still further objectives and advantages will become apparent from a consideration of the ensuing description. 
     In accordance with the present invention the seal between the cable and the conduit is effected when a gasket is compressed or expanded by the simple means of rotating a cam member into a locked position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows three orthogonal views of a lug half. 
     FIG. 2 shows two orthogonal views of a bearing half. 
     FIG. 3 shows two orthogonal views of a gasket. 
     FIG. 4 shows two orthogonal views of a cam. 
     FIG. 5 shows a end view of a completed seal assembly spread apart so as to fit over a cable. 
     FIG. 6 shows three orthogonal views of the assembly of the invention installed over a cable and into a conduit with a cam in a relaxed position and an additional view showing the cam in an actuated position. 
     FIG. 7 shows three orthogonal views of a lug half in a second embodiment. 
     FIG. 8 shows two orthogonal views of a bearing half in a second embodiment. 
     FIG. 9 shows two orthogonal views of an inside gasket in a second embodiment. 
     FIG. 10 shows two orthogonal views of an outside gasket in a second embodiment. 
     FIG. 11 shows a cross-section of a seal with inclines that urge gaskets into engagement with the cable and conduit. 
     FIGS. 12A, B, C, D and E show different slits of typical gaskets. 
    
    
     REFERENCE NUMERALS IN DRAWINGS 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 10 Lug Half 
                 12 Flange 
                 14 Arm 
               
               
                   
                 16 Hole 
                 20 Bearing Half 
                 22 Body 
               
               
                   
                 24 Flange 
                 26 Ring 
                 28 Slot 
               
               
                   
                 30 Gasket 
                 32 Slot 
                 34 Slit 
               
               
                   
                 40 Cam 
                 42 Arm 
                 44 Handle 
               
               
                   
                 46 Boss 
                 48 Cam Surface 
                 50 Cable 
               
               
                   
                 52 Conduit 
                 54 Ledge 
                 60 Seal Assembly 
               
               
                   
                 70 Inner Gasket 
                 72 Outer Gasket 
                 80 Lug Half 
               
               
                   
                 82 Shroud 
                 84 Arm 
                 90 Bearing Half 
               
               
                   
                 92 Recess 
                 94 Slot 
                 96 Flange 
               
               
                   
                 100 Seal Assembly 
                 110 Incline 
               
               
                   
                   
               
             
          
         
       
     
     DETAILED DESCRIPTION OF THE INVENTION 
     In the first preferred embodiment, lug half  10 , as shown in FIG. 1, has a semicircular annular flange  12  from which extends a centrally located arm  14  of abbreviated annular shape. Near the end of the arm  14  opposite the flange  12  is a centrally located hole  16 . 
     Bearing half  20 , as shown in FIG. 2 has an semicircular annular body  22  with a flange  24  at one end. A small semicircular annular integral ring  26  is located at the intersection of the body  22  and the flange  24 . A slot  28  is centrally located in the body  22  that is of size to accept arm  14  of lug half  10 . 
     Gasket  30  shown in FIG. 3 is tubular with two slots  32  diametrically opposed in position to accept arms  14  of lug halves  10 . At approximately the midpoint between the two slots  32 , gasket  30  is slit  34 . Gasket  30  is made of resilient material. 
     Cam  40 , as shown in FIG. 5, has two flexible arms  42  joined by a handle  44 . Flexible arms  42  have generally cylindrical bosses  46  for engagement with holes  16  in lug halves  10 . Cam surface  48  will bear against flange  24  of bearing half  20  when assembled as will be shown. 
     To form the seal assembly  60 , slots  32  of gasket  30  are slid over arms  14  of two lug halves  10  until gasket  30  abuts flange  12 . Two bearing halves  20  are then slid over the extending arms  14  through slots  28 . Arms  14  now extend sufficiently through bearing halves  20  so that cam  40  can be installed. Seal assembly  60  is completed when cam  40  is joined to lug halves  10  by spreading flexible arms  42  and placing bosses  46  into exposed holes  16  in arms  14 . 
     The entire seal assembly  60  can now be spread, as shown in FIG. 5, sufficiently to encompass cable  50 . 
     As shown in FIG. 6 seal assembly  60  is now ready to slide over cable  50  and into conduit  52  until ring  26  abuts the end of conduit  52 . Ring  26  is provided to space flange  24  away from conduit  52  to permit easy grasping of flange  24  to facilitate removal of seal assembly  60 . Seal assembly  60  is locked in place when the cam  40  is rotated to the position shown in the upper right hand view of FIG.  6 . At this point gasket  30  is compressed and the outside diameter is increased and inside diameter is decreased sufficiently to make a appropriate seal between cable  50  and conduit  52 . 
     Ledge  54  is provided on flange  24  to capture cam surface  48  and prevent any forces from causing bosses  46  from leaving holes  16 . 
     Thus lug halves  10  and bearing halves  20  provide a supporting structure for gasket  30  which is expanded into sealing contact with the conduit and cable when cam  40  is actuated. 
     In the second embodiment (FIG.  11 ), two separate gaskets are used in seal assembly  100 . Inner gasket  70  is shown in FIG. 9 with slit  72  and outer gasket  74  is shown in FIG. 10 with slit  76 . In FIG. 11 inner gasket  70  is wrapped around the cable  50 . 
     Two lug halves  80  are placed diametrically opposed over the gasket  70  so that shroud  82  (FIG. 7) covers gasket  70 . Outer gasket  74  is then wrapped around shroud  82  adjacent to flange  96 . Bearing halves  90  have a recess  92  (FIG. 8) to accept the shroud  82 . Arms  84  fit through the slots  94 . Cam  40  is installed the same as in the first preferred embodiment. When cam  40  is rotated to its locked position both inner gasket  70  and outer gasket  74  are compressed. This causes sealing to occur between cable  50  and shroud  82 , and between shroud  82  and conduit  52 . Inclines  110  may be added to lug halves  80  to augment sealing. 
     FIG. 12A through D show several methods of slitting gaskets  30 ,  70  and  72 . FIG. 12A shows a radial and axial on centerline slit. FIG. 12B shows a radial but axially angled slit. FIG. 12C shows a slit angled with a radius and axially on centerline. FIG. 12D shows a slit at an angle with a radius and also at an angle with axial centerline. Yet another version of gaskets  30 ,  70  and  72  is shown in FIG.  12 E. In this version the gasket  30 ,  70  and  72  are split into two pieces axially as well as being slit in any of schemes shown in FIGS. 12A, B, C and D. These different techniques of slitting can have advantages in effectiveness of sealing by creating a more torturous path for leakage. These gaskets are made of resilient material such as synthetic rubber. Another material of preference for these gaskets is closed cell, low compression set, foam rubber. Synthetic rubber materials, when totally contained, act as incompressible fluids when under compressive loading. Closed cell foam, with its air filled cells, avoids this phenomenon, and acts as a compressible material. 
     CONCLUSIONS 
     Therefore, it can be seen from the foregoing specification, that this invention provides a unique seal between a terminated conduit end and the cable that runs through it. 
     The seal is extremely cost effective. For example, both lug halves are identical which reduces the manufacturing costs. The same is true for the bearing halves. The supporting parts can be made using inexpensive plastic material. The gasket(s) can be made by molding, extrusion or die-cut processes allowing a variety of manufacturing techniques. 
     The seal is easily assembled and easily installed. The first preferred embodiment requires no assembly at the installation site, which is not the case with prior art. The gasket compression is positive and mechanically limited. This controls the compression of the gasket(s) and consequently the force transmitted to the cable and the conduit. The seal accommodates variations in the diameter of the cable and the conduit while still providing an excellent seal. 
     Materials can be selected that provide excellent corrosion resistance and environmental compatibility. 
     It will be appreciated that while particular embodiments of the invention have been shown and described, modifications may be made. It is intended in the claims to cover all modification which come within the true spirit and scope of the invention.