Abstract:
A system for coupling conduit sections includes a coupling tool with a pair of lever arms pivotally interconnected and each mounting a clamp assembly. The clamp assemblies are adapted for releasably clamping the conduit sections. A coupling has a generally tubular configuration with a throughbore with multiple annular internal ribs. A coupling method includes the steps of clamping first and second conduit sections with respective clamping assemblies, placing the conduit section ends against the coupling throughbore ends, and squeezing the tool lever arms together whereby the conduit section ends are inserted into the coupling throughbore in fluid-tight sealing and pull-out resistant engagement.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to conduit or pipe couplings, and in particular to a system, tool and method for pushing the ends of a pair of plastic conduit sections into a coupling to form a fluid-tight, pull-out resistant coupling therebetween. 
   2. Discussion of the Related Art 
   Couplings and fittings of various types are used for joining pipes and conduits. Examples include threaded fittings, couplings that are secured with solvent adhesives, weldments and various push-type couplings. The performance criteria for pipe coupling mechanisms are generally determined by such factors as the pipe materials, design pressures, temperature ranges, fluid-tight requirements, pull-out resistance requirements and environmental conditions. 
   For example, the nationwide, fiber-optic, telecommunications networks consist largely of buried fiber-optic cables. The cables are commonly protected from groundwater and other subsurface conditions by enclosing them within plastic conduits. A common fiber-optic cable installation procedure involves placing the empty conduits below grade with special trenching and tunnel-boring equipment, whereafter the fiber-optic cables are blown through the conduit with high-pressure air. The plastic conduits and the connecting fittings used in such installations must be impervious to groundwater, resistant to the corrosive effects of soil and capable of maintaining relatively high internal air pressures. Therefore, the connecting fittings or couplings used for joining the conduit sections require sufficient pull-out resistance to withstand internal air pressures, and further to resist tensile forces tending to separate the conduit sections by pulling apart their connections. 
   Conduit coupling systems are commonly used in adverse field and environmental conditions where only minimal equipment is available and speed is relatively important. Therefore, machining and other preparation of the conduit sections ends should be eliminated or minimized. Manually-operated hand tools are generally preferred due to their portability and independence from external power sources. Moreover, the couplings and other fittings should be relatively simple, inexpensive, strong and reliable. Still further, the bores of the aligned conduit sections should be free from obstructions after they are coupled. 
   Heretofore there has not been available a conduit coupling system, tool and method with the advantages and features of the present invention. 
   BRIEF DESCRIPTION OF THE INVENTION 
   In the practice of one aspect of the present invention, a coupling system, tool and method are provided for continuously fluidically connecting a pair of conduit sections with a coupling having internal, annular ribs adapted and oriented to pass the conduit section ends one-way into the coupling and to resist pull-out in the opposite direction. The tool comprises a pivotally interconnected pair of lever arms each mounting a respective clamp assembly. Practicing an aspect of the method of the present invention involves clamping the conduit sections with the clamp assemblies, spreading the lever arms to their open position, placing a coupling between the conduit sections ends and closing the lever arms whereby the conduit section ends are pushed into and fixedly received in the coupling. Pull-out resistance is provided by the coupling internal ribs, which impinge on the conduit sections for securely retaining same in fluid-tight engagement with the coupling. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof. 
       FIG. 1  is a perspective view of a conduit coupling tool embodying an aspect of the present invention, with the conduit sections and the coupling shown in phantom lines. 
       FIG. 2  is a front elevational view thereof. 
       FIG. 3  is a side elevational view thereof. 
       FIG. 4  is an enlarged, fragmentary, cross-sectional view of a clamp assembly and the coupling, taken generally within circle  4  in  FIG. 2  and showing the conduit section ends in phantom lines and in position for insertion into the coupling with the coupling tool in its open position. 
       FIG. 5  is an enlarged, front elevational view of the clamp assembly on the left and a cross-sectional view of the clamp assembly on the right and the coupling, with the conduit section ends fixedly embedded in the coupling and the coupling tool in its closed position. 
       FIG. 6  is an enlarged, side elevational view of a clamp assembly taken generally along line  6 — 6  in  FIG. 4 , with the clamp assembly in its closed position. 
       FIG. 7  is an enlarged, side elevational view of the clamp assembly in its open position with a conduit section being extracted therefrom. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   I. Introduction and Environment 
   As required, detailed embodiments and/or aspects of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments/aspects are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. 
   Referring to the drawings in more detail, the reference numeral  2  generally designates a coupling tool adapted for inserting the ends of conduit sections  4 ,  6  into a tubular coupling  8 . Without limitation on the generality of useful applications of the coupling tool  2 , the conduit sections  4 ,  6  can comprise various suitable plastics, such as polyvinyl chloride (PVC) polyethylene, polypropylene, etc. The tool  2  generally comprises a lever assembly  10  and a pair of clamp assemblies  12  mounted thereon. 
   II. Coupling Tool  2   
   The lever assembly  10  comprises a pair of lever arms  13 ,  14 , which are pivotally interconnected by a pivot connector  16 . The lever arms  13 ,  14  include respective, proximal handle ends  18 ,  20  and distal ends  22 ,  24 , which mount the clamp assemblies  12 . 
   Each clamp assembly  12  includes a stationary jaw  26  and a movable jaw  28  movably mounted thereon by a hinge  30  attached to the undersides of the jaws  26 ,  28 . The stationary jaw  26  is rotatably mounted on a respective lever arm distal end  22  or  24  by an axle  32 , with a coaxial rotational axis  34  extending perpendicularly from the lever arm distal end  22  or  24 . The axle  32  is fixedly retained in place in the stationary jaw  26  by an axle retainer screw  33 , which extends through the hinge  30 , the axle  32  and into the stationary jaw  26  ( FIGS. 6 and 7 ). The jaws  26 ,  28  include respective engagement faces  36 ,  38  with respective conduit receiver halves  40 ,  42 . With the jaws  26 ,  28  closed, the receiver halves  40 ,  42  are positioned in opposed relation to form a conduit receiver  44  ( FIG. 6 ). Each receiver half  40 ,  42  includes multiple, semi-circular arcuate receiver ribs  46  with sawtooth-shaped cross-sections forming engagement edges  48  adapted for grippingly engaging the conduit sections  4 ,  6  ( FIGS. 4 and 5 ). 
   The jaws  26 ,  28  include respective latch channels  52 ,  54 , which partially receive respective latch mechanisms  56  adapted for selectively latching and tightening the clamp assemblies  12 . Each latch mechanism  56  includes a latch bolt  58  with an inner, retained end  60  mounting a cross pin  62  pivotally received in respective cross pin receivers  64  located on opposite sides of the stationary jaw  26  and its latch channel  52 . Each latch bolt includes a threaded outer end  66  threadably mounting a knurled nut  68  adapted for manual tightening whereby the clamp assembly  12  securely clamps a respective conduit sections  4  or  6 . An alignment mechanism  70  interconnects the clamp assemblies  12  and includes an alignment rod  72 , which slidably extends through respective, transverse guide rod passages  74  formed in the stationary jaws  26 . The rod  72  includes opposite ends  76  protruding beyond the stationary jaws  26  and mounting retainers  78 , which are adapted for limiting the range of motion of the lever arms  13  at their maximum spread ( FIG. 2 ). 
   III. Coupling  8  and Operation 
   In operation, the tool  2  is adapted for inserting the ends of the conduit sections  4 ,  6  into the coupling  8 . The coupling  8  includes a throughbore  80  with first and second sections  81 ,  82 , which are separated by an annular center stop  84  located approximately midway through the throughbore  80 . Each throughbore section  81 ,  82  includes multiple, annular coupling ribs  86  with sawtooth-shaped cross-sectional configurations, which are somewhat similar to the configurations of the clamp jaw receiver ribs  46  ( FIGS. 4 and 5 ). The coupling ribs  86  likewise define relatively sharp, annular engagement edges  88 , with inside diameters D. 1 , which are slightly less than outside diameters D. 2  of the conduit sections  4 ,  6 . The coupling  8  preferably comprises a relatively hard material, such as polycarbonate, whereby the coupling rib edges  88  impinge on the conduit section outer surfaces, forming a fluid-tight, pull-out resistant sealing connection therebetween. The coupling  8  can comprise a transparent or translucent plastic material adapted for visual observation of the conduit section ends within the coupling. The contents of the conduits, such as fiber-optic cables, fluids and the like, can also be observed through a clear, see-through coupling. Alternatively, the coupling  8  can comprise another suitable material, such as metal. The sawtooth configuration of the coupling ribs  86  functions to permit one-way passage of the conduit sections  4 ,  6  into the coupling throughbore  80 , while resisting pull-out in the opposite direction. 
   The conduit sections  4 ,  6  are placed in the clamp receivers  44  with the clamp assemblies  12  opened ( FIG. 7 ), whereafter the clamp assemblies  12  are securely clamped on the conduit sections  4 , 6  by tightening the latch mechanism nuts  68  ( FIG. 6 ) whereby the engagement edges  48  of the receiver ribs  46  impinge on the conduit sections  4 ,  6 . With the lever assembly  10  in its closed position, the conduit sections  4 ,  6  can be properly positioned in the clamp assemblies  12  with their ends touching or nearly touching. The lever assembly  10  is then spread to provide clearance between the conduit section ends for the coupling  8  ( FIGS. 2 and 4 ). The lever assembly  10  provides considerable leverage whereby substantial compressive forces can be applied for securely embedding the conduit section ends in the respective throughbore first and second sections  81 ,  82 . The sawtooth configurations of the clamp receiver ribs  46  function to effectively resist slippage of the captured conduit sections  4 , 6  and effectively transmit compressive forces, which insert the conduit section ends into the coupling  8 . The alignment mechanism  70  rotates the clamp assemblies  12  on the lever arms  13 ,  14  about the rotational axes  34  whereby the clamp assembly conduit receivers  44  are maintained in axial alignment with the conduit sections  4 ,  6  and the coupling  8 . 
   It will be appreciated that the pull-out resistant coupling can be configured in various alternative aspects and embodiments within the scope of the present invention. For example, the tool  2  can be adapted for connecting conduit sections with various other types of fittings, such as reducers, Ts, elbows, etc. Moreover, external hydraulic, electrical or other power sources can be utilized for opening and closing the clamp assemblies.