Abstract:
A coupling for connecting pipes to externally threaded fittings and stubs. The coupling comprises a coupling body, a gripper, gripper engagement means for causing the gripper to engage the pipe, a gasket, gasket engagement means for causing the gasket to seal around the pipe, gripper retention means for retaining the gripper within the interior of the coupling body during handling thereof, and gasket retaining means for retaining the gasket within the interior of the coupling body during handling thereof.

Description:
[0001]     This application claims priority from Canadian Patent application number 2,459,637 filed on Feb. 27, 2004.  
       FIELD OF THE INVENTION  
       [0002]     The invention relates to pipe couplings, and in particular to couplings used to connect pipes to fittings such as valves, adapters or other fittings.  
       BACKGROUND OF THE INVENTION  
       [0003]     Particularly in the plumbing and waterworks industries, situations frequently arise during installation or repair of piping where it is necessary to connect pipes to various fittings such as corporation valves, curb valves and various adapters. These situations can arise for example during water service line installation or repair. Such piping can include service tubes and may be made of polyvinylchloride (PVC) or galvanized steel for example.  
         [0004]     Typically, such fittings are provided with a stub, usually externally threaded, for receiving a sealed fluid communicating connection with the pipe. The threading on such stubs are typically of an industry standard such as corporation fitting thread, to allow similarly-threaded couplings to be mounted thereon.  
         [0005]     Such pipe-fitting couplings typically come in two main forms. In a first form the coupling is integral with the pipe. The present invention is directed to the second form wherein the coupling is a separate device which clamps on to, or is otherwise sealingly affixed to the end of the pipe. In either case the end of the coupling intended to engage the fitting stub is provided with internal threading and the coupling is connected to the fitting stub by turning one relative to the other thereby engaging the internal threading of the coupling with the external threading of the stub.  
         [0006]     A typical manner in which such a separate coupling is used to connect a pipe to a fitting stub is as follows. First a coupling body, having internal threads at a forward end for engaging the external threads of the stub, and a constricted rearward end, is slid on to the pipe, rearward end first. A combination of various internal elements including seals and camming or gripping means are then slid on to the pipe. During this process it is imperative that each of the internal elements be placed on the pipe in the correct order and in the correct orientation. Failure to do so will typically result in failure of the connection. Finally, the coupling body is screwed onto the stub trapping and compressing the seals and the camming or gripping means. In particular, the constricted rearward end of the coupling body presses the seals and camming or gripping means against the end of the stub, or against the side of the pipe. The compressed seals create a hydrostatic seal between the stub and the pipe, while the camming or gripping means are urged to a locking and restraining position preventing the pipe from being pulled out of the coupling inadvertently. Using such a coupling, a secure pressure-sealed connection is made. An example of such a coupling for plumbing applications is described in U.S. Pat. No. 5,580,105 Miller Jr. et al. issued Dec. 3, 1996.  
         [0007]     One difficulty with such couplings is the need for the user to handle a number of small elements (typically the internal elements) during installation. This can result in frustration on the part of the user while he fumbles with the various parts to ensure that they are installed in the correct order and orientation. As noted above, if the user fails to install these parts in the correct order and orientation, the connection can fail resulting in leakage. This disadvantage is particularly acute where installation takes place in difficult conditions, for example where the fitting is located in an awkward location, or where the installation is taking place on waterworks, often with the user standing in a wet and muddy hole where fingers are slippery and where a dropped part is irretrievably lost.  
         [0008]     Another difficulty with such couplings is that the camming or gripping means are typically unitary circumferentially, or consist of a small number of wide grips spaced circumferentially. Thus if a unitary camming or gripping means fails, the coupling itself fails. Similarly, if one of a small number of grips fails, the strength of the coupling will be compromised. Further, with a unitary camming or gripping means or with wide grips, it is difficult to achieve positive attachment to pipes which are slightly out of round or which have an irregular outer surface (as is often the case with galvanized steel pipes).  
         [0009]     Additionally, most present couplings are not reusable since the camming or gripping means used are permanently deformed during use.  
         [0010]     Finally, with most present couplings the coupling can easily be under-tightened or over-tightened onto the pipe and/or the fitting, which may result in damage to the pipe, to the fitting, and/or to the coupling and may also result in failure of the coupling.  
       SUMMARY OF THE INVENTION  
       [0011]     This invention provides an improved coupling for connecting pipes to fittings.  
         [0012]     The present invention provides a coupling for creating a fluid-conducting connection between a pipe and a stub. The coupling includes a coupling body having a forward end for being secured to the stub, a rearward end for receiving the pipe, and an internal bore. A stub securing means secures the forward end of the coupling body to the stub. A gripper located within the internal bore of the coupling body is provided for gripping the pipe. A gripper retaining means retains the gripper within the coupling body during handling of the coupling body. A gasket located within the internal bore of the coupling body creates a seal around the pipe. A gasket retaining means retains the gasket within the coupling body during handling of the coupling body. A gripper engaging means is provided that causes the gripper to grip the pipe. A gasket engaging means creates a seal with the gasket around the pipe. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     Preferred embodiments of the invention will now be described with reference to the attached drawings in which:  
         [0014]      FIG. 1  is a side cross-sectional view of a coupling in accordance with a preferred embodiment of the present invention, installed on a fitting stub and pipe;  
         [0015]      FIG. 2  is an exploded side view of the coupling;  
         [0016]      FIG. 3  is a side partial cross-sectional view of the coupling;  
         [0017]      FIG. 4  is a side cross-sectional view of a coupling body of the coupling;  
         [0018]      FIG. 5  is a side view of a gripper of the coupling;  
         [0019]      FIG. 6  is a side cross-sectional view of a gasket of the coupling; and  
         [0020]      FIG. 7  is a side cross-sectional view of an adapter of the coupling. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     A preferred embodiment of the coupling of the present invention is shown in the attached drawings. In the exemplary application illustrated, the coupling is used to connect a-PVC pipe to a cast brass alloy fitting stub in a waterworks application. The coupling is located between the pipe and the stub.  
         [0022]     In this description and in the claims, the terms ‘axial” and “axially” are used to describe a direction parallel to a centerline of the pipe once the coupling is installed, while “radial” and “radially” are used to describe a direction perpendicular to and extending from the centerline of the pipe once the coupling is installed. Further, “forward” is used to describe features which are located nearer the fitting stub and away from the pipe once the coupling is installed, while ‘rearward” is used to describe features which are located nearer the extended pipe and away from the fitting stub once the coupling is installed.  
         [0023]      FIG. 1  is a cross-sectional view of the coupling  10  installed on a fitting stub  22  and pipe  24 . The coupling  10  consists mainly of a coupling body  12 , a gripper  14 , a gasket  16 , and an adapter  18  having a seal  20 . The coupling  10  is shown affixed to the stub  22  of a fitting (not shown), and with the pipe  24  installed therein. In this exemplary application, the fitting can be any plumbing or waterworks fitting having an externally-threaded stub  22  having the features described herein, onto which it is desirable to connect the pipe  24 . The top half of  FIG. 1  depicts the coupling  10  loosely engaging the stub  22  while the bottom half shows the coupling  10  tightened on to the stub  22 .  FIG. 2  shows an exploded side view of the coupling  10  while  FIG. 3  shows a side partial cross-sectional view of the coupling.  
         [0000]     Coupling Body  
         [0024]     Referring to  FIG. 4 , the coupling body  12  is made of cast-brass alloy and is generally a hollow cylinder. The coupling body  12  has a nut section  26  at a forward end, a constricted section  28  at a rearward end, and an intermediate section  30  in between.  
         [0025]     The nut section  26  of the coupling body  12  is provided with a hexagonal exterior to accommodate hand tightening or tool-tightening of the coupling body  12  on to the fitting stub  22 . The interior of the nut section  26  is sized so as to engage an outer surface of the stub  22  and is provided with internal threading  31  which matches the external threading  33  of the stub  22 . The threading  31 ,  33  on the stub  22  and the interior of the nut section  26  is corporation fitting thread, though it is to be understood that other threads can be used. A forward end of the nut section  26  is provided with a flat face  35  which abuts a rearward face  37  of a shoulder  39  on the stub  22  when the coupling body  12  is fully tightened onto the stub  22  as shown in the bottom half of  FIG. 1 .  
         [0026]     The coupling body  12  is provided at its rearward end with a constricted section  28  having an interior constriction  32 . The interior constriction  32  is sized so as to fit closely over the pipe  24  and serves to retain the gripper  14 , gasket  16  and adapter  18  within the coupling body  12  when the coupling body  12  is screwed onto the stub  22 .  
         [0027]     Located at an interface between the constricted section  28  and the intermediate section  30  is a gripper constricting slope  34  which is an angled surface in the interior of the coupling body  12  formed as the interior diameter of the coupling body  12  expands from the interior constriction  32  to a gripper retainer groove  36 . This gripper-constricting slope  34  causes the gripper  14  to constrict around the pipe  24  once the coupling body  12  is tightened onto the stub  22 . The angle of the gripper 20  constricting slope  34  is approximately 45 degrees though it is to be understood that other suitable angles may be utilized.  
         [0028]     Adjacent the gripper-constricting slope  34  is the gripper retainer groove  36  which is an interior circumferential groove formed in the coupling body  12  and which has a square forward face  37 . The gripper retaining groove  36  retains the gripper  14  in place within the coupling body  12 .  
         [0029]     In the interior of the intermediate section  30  of the coupling body  12 , and spaced from the gripper retainer groove  36  is a gasket retaining groove  38  which is an internal circumferential groove which serves to retain the gasket  16  in place within the coupling body  12 .  
         [0000]     Gripper  
         [0030]     Referring to  FIG. 5 , gripper  14  is made of phosphor bronze and is an annular ring  40  having fingers  42  extending rearwardly therefrom.  
         [0031]     The annular ring  40  has an inner diameter sized so as to closely fit over the pipe  24  and an outer diameter sized so as to closely fit within the intermediate portion  30  of the coupling body  12 . The annular ring  40  has at a forward end a sloped forward face  44  such that the axial length of the annular ring  40  at an interior surface is less than that at an exterior surface. This sloped forward face  44  assists in forcing the gasket  16  onto the pipe  24  during use.  
         [0032]     From a rearward end of the annular ring  40  of the gripper  14  extend rearwardly, eight circumferentially spaced fingers  42 . Each finger  42  has a neck  46  and a head  48 . The neck  46  is of rectangular cross-section and has a reduced thickness so as to allow it to flex during use, thereby allowing the head  48  to be displaced radially during use.  
         [0033]     Each head  48  of the fingers  42  of the gripper  14  includes an exterior protrusion  50  which is shaped to fit the gripper retaining groove  36  of the coupling body  12 . The protrusion  50  has a blunt forward surface  52  which abuts the square forward face  37  of the gripper retaining groove  36  to resist movement of the gripper  14  out of the coupling body  12  once it is installed therein and a sloped rearward surface  54 . The sloped rearward surface  54   
         [0034]      30  engages the gripper constricting slope  34  of the coupling body such that as the gripper  14  is moved rearwardly, the sloped rearward surface  54  slides along the gripper constricting slope  34 , thereby displacing the heads  48  of the fingers  42  inwardly.  
         [0035]     Each head  48  also includes on its interior surface, teeth  56  designed to bite into the pipe  24  when the head  48  is displaced inwardly against the pipe  24 . These teeth  56  are Buttress style such that once they engage an outer surface of the pipe  24 , any axial force on the pipe tending to pull it out of the coupling  10  will result in the teeth  56  biting more deeply into the outer surface of the pipe  24 .  
         [0036]     Eight fingers  42  are provided along the periphery of the gripper  14 . It is to be noted however that the number of fingers may be varied depending on the particular application, as will be understood by persons in the trade.  
         [0000]     Gasket  
         [0037]     Referring to  FIG. 6 , the gasket  16  is made of nitrile rubber and is an annular ring having a substantially trapezoidal cross-section. An inner diameter of the gasket  16  is chosen so as to closely fit over the pipe  24 . An outer diameter of the gasket is chosen so as to closely fit within the coupling body  12 .  
         [0038]     Both a forward end  58  and a rearward end  60  of the gasket  16  are sloped such that the axial length of the gasket  16  is greater at its radially inner surface than at its outer surface. In the preferred embodiment the angle of the slope of the forward end  58  is approximately 45 degrees while the angle of the slope of the rearward end  60  is approximately 10 degrees. The slopes of the forward end  58  and rearward end  60  cooperate with a sloped portion of the adapter  18  and the sloped face  44  of the gripper  14  respectively, to press the gasket  16  into the pipe  24  once the coupling body  12  is tightened onto the stub  22 .  
         [0039]     The gasket is also provided on its exterior surface with a circumferential protrusion  62  having a profile adapted to fit within the gasket retaining groove  38 .  
         [0000]     Adapter  
         [0040]     Referring to  FIG. 7 , the adapter  18  is made of copper alloy and consists, moving from its forward end to its rearward end, of an inner web  62 , an intermediate section  64  and an outer web  66 .  
         [0041]     The inner web  62  is of a smaller diameter than the outer web  66  and its exterior surface is sized to fit closely within an inner surface of the stub  22 . The inner web also has on its outer surface a circumferential seal groove  68  shaped and sized to accommodate the seal  20 .  
         [0042]     The intermediate section  64  connects the inner web  62  and the outer web  66 , has a forward face  70  shaped to engage a rearward end face of the stub  22 , and a rearward face  72  shaped to engage a forward end face of the pipe  24 .  
         [0043]     The outer web  66  is sized such that its outer surface closely fits within the coupling body  12  and its inner surface closely fits over the pipe  24 . A rearward face  73  of the outer web  66  is angled 45 degrees so as to engage the sloped forward end  58  of the gasket  16 .  
         [0000]     Use  
         [0044]     A description of an exemplary manner in which the coupling of the present invention may be used is set out below.  
         [0045]     Referring to  FIGS. 2 and 3 , first, the coupling body  12 , gripper  14  and gasket  16  are assembled. To do so, the gripper  14  is slid into the forward end of the coupling body  12  with the fingers  42  of the gripper  14  pointed rearwardly. This step can be performed either manually, or using an insertion device. The sloped rearward surface  54  of the fingers  42  of the gripper  14  assist in inserting the gripper  14  within the coupling body  12  and serve to displace the heads  48  of the fingers  42  slightly inwardly since the exterior diameter of the exterior protrusions  50  of the heads  48  is slightly greater than the diameter of the inner surface of the intermediate section  30  of the coupling body  12 .  
         [0046]     The gripper  14  is pushed into the coupling body  12  until the exterior protrusions  50  of the heads  48  of the fingers  42  of the gripper  14  reach the gripper retaining groove  36  on the interior surface of the coupling body  12  at which point the resiliency of the necks  46  of the fingers  42  cause the heads  48  to expand to their original positions. Once in this position, the gripper  14  is locked in place as the blunt forward faces  52  of the heads  48  abut against the square forward surface  37  of the gripper retaining groove  36  in the coupling body  12 , and the sloped rearward surfaces  54  of the heads  48  abut against the gripper constricting slope  34  of the coupling body  12 .  
         [0047]     The gasket  16  is then inserted into the coupling body  12  in the same manner until the sloped rearward end  60  of the gasket abuts against the sloped forward face  44  of the gripper  14 , and the exterior protrusion  62  of the gasket  16  engages the gasket retaining groove  38  in the coupling body  12 . The gasket  16  is retained in place by the engagement of the exterior protrusion  62  of the gasket  16  into this retaining groove  38 .  
         [0048]     Thus, once the gripper  14  and the gasket  16  are positioned within the coupling body  12  as described, the gripper  14  and gasket  16  are held in place and will not fall out under normal handling. Neither the gripper  14  nor the gasket  16  will lock in place if inserted in an incorrect orientation.  
         [0049]     The assembly of the coupling body  12 , gripper  14  and gasket  16  may be performed at the factory such that the user receives a preassembled unit, or the user may assemble these elements just prior to use. Once the coupling body  12 , gripper  14  and gasket  16  are assembled into an assembled coupling body, the only remaining loose part of the coupling  10  is the adapter  18  which comes preassembled with the seal  20  mounted thereon.  
         [0050]     Referring to  FIG. 1 , at a work site, the adapter  18  is first inserted into the fitting stub  22  such that the inner web  62  of the adapter  18  resides within the end of the stub  22 . The adapter  18 : is slid into the stub  22  until the rearward end face of the stub  22  engages the forward face  70  of the intermediate section  64  of the adapter  18 . In this position, the seal  20  creates a seal against the stub  22  thereby preventing leakage of fluid out the forward end of the coupling.  
         [0051]     The coupling body assembly is then placed over the adapter  18  such that the forward end of the coupling body  12  slides over the outer web  66  of the adapter  18  until the internal threading  31  of the nut section  26  of the coupling body  12  first engages the exterior threading  33  of the stub  22 . The coupling body  12  is then hand-tightened onto the stub  22 , thereby further engaging the interior threading  31  of the coupling body  12  and the exterior threading  33  of the stub  22 , and moving the coupling body  12  further over the adapter  18  and the stub  22 . Typically, the coupling body  12  is hand-tightened onto the stub  22  until the rearward face  73  of the outer web  66  of the adapter  18  abuts against the forward end  58  of the gasket  16 , thereby creating some resistance to further tightening.  
         [0052]     The pipe  24  is then “stab-fitted” into the rearward opening of the coupling body  12  and pushed forward until the forward end face of the pipe  24  abuts against the rearward face  72  of the intermediate section  64  of the adapter  18 .  
         [0053]     The coupling body  12  is then further tightened onto the stub  22  either by hand or by using a tool. Because the stub  22 , the adapter  18 , the gasket  16 , the gripper  14  and the interior constriction  32  of the coupling body  12  all abut against one another, this further tightening causes the gasket  16  and the gripper  14  to move and compress to accommodate the decreasing distance between the rearward face  73  of the outer web  66  of the adapter  18  and the gripper-constricting slope  34 .  
         [0054]     First, this further tightening causes the gasket  16  to move rearwardly slightly. Additionally, as a result of the cooperation between the sloped surfaces of the rearward face  73  of the outer web  66  and the forward end  58  of the gasket  16 , and between the sloped forward face  44  of the gripper  14  and the rearward end  60  of the gasket  16 , decreasing the distance between the adapter  18  and the gripper  14  results in the gasket  16  being urged inwardly against the pipe thereby creating a seal against the pipe, preventing leakage out the rearward end of the coupling  10 . Both effects are illustrated in the bottom half of  FIG. 1 .  
         [0055]     Second, decreasing the distance between the rearward face  73  of the outer web  66  of the adapter  18  and the gripper constricting slope  34  causes the gripper  14  to move rearwardly. As it does so, cooperation between the sloped rearward surface  54  of the fingers  42  of the gripper  14  and the gripper constricting slope  34  of the coupling body  12  causes the heads  48  of the fingers  42  to be urged inwardly, thereby resulting in an engagement of the outer surface of the pipe  24  by the teeth  56  of the heads  48  of the gripper  14 .  
         [0056]     Further tightening of the coupling body  12  onto the stub  22  causes the gasket  16  to be urged more securely against the pipe  24  and also causes the teeth  56  of the heads  48  of the gripper  14  to engage the outer surface of the pipe  24  more securely.  
         [0057]     Once the forward flat face  35  of the nut section  26  of the coupling body  12  abuts the rearward face  37  of the shoulder  39  of the stub  22 , the coupling  10  is fully engaged and a sealed, secured connection between the pipe  24  and the stub  22  has been established. As designed, an ideal seal, and securement is established by the coupling  10  when the coupling body  12  is fully tightened onto the nut with the forward flat face  35  of the nut section  26  of the coupling body abutting the rearward face  37  of the shoulder  39  of the stub  22 . Thus, it is easy for a user to tell if the coupling  10  is undertightened, and it is not possible for the coupling  10  to be over-tightened.  
         [0058]     To release the connection, the coupling body  12  is simply loosened off the stub  22  thereby disengaging the gasket  16  as well as the teeth  56  of the gripper  14  from the pipe  24 . The coupling body assembly can then be removed from the stub  22  and the pipe  24  can be slid out of the coupling body assembly.  
         [0059]     Because none of the elements of the coupling are permanently deformed during use, the coupling  10  can be reused.  
         [0060]     Although an exemplary manner of using the coupling of the present invention has been described above in detail, it is to be understood that the coupling can be used in ways other than as explicitly set out above, as readily understood by those skilled in the art. For example, instead of mounting the adapter  18  within the stub  22  first and placing the assembled coupling body over the adapter, the adapter  18  can be placed within the coupling body assembly first and then the coupling body assembly with adapter  18  within may be placed onto the stub  22 . As a further example, the pipe  24  may be inserted is into the coupling body assembly first before the adapter  18  is installed in the coupling body  12 , or the coupling body assembly placed over the adapter  18  and stub  22 .  
         [0061]     Although the coupling has been described above as being used to attach a PVC pipe  24  to a fitting, it is to be understood that pipes made of other materials may be used, galvanized steel, copper or polyethylene for example. Indeed any pipe having sufficient rigidity to avoid excessive deformation during tightening and which has a surface soft enough to permit the teeth  56  of the gripper  14  to bite into it, may be used. For additional pull-out restraint a stiffener (either integral to the coupling or as a separate element) can be inserted into the end of the pipe  24 .  
         [0062]     Specific materials used for the various elements of the coupling  10  and for the fitting  22  have been provided. However, it is to be understood that other suitable materials may be used for these elements as will be understood by those skilled in the art.  
         [0063]     Very specific geometries of the various elements have also been provided. However, it is to be understood that other suitable geometries may be used by persons skilled in the art without necessarily departing from the scope of the invention.  
         [0064]     The coupling has also been described in the context of a waterworks application. However, it is to be understood that the coupling can be used in other applications, plumbing applications for example.  
         [0065]     Numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.