Abstract:
A coupling assembly for inserting into and coupling with the end of an open pipe, such as a cleanout pipe used in plumbing systems and wherein the coupling assembly may be used as a plug. The coupling assembly includes a collar secured around a medial portion of the cylindrical body of reduced diameter. The collar is driven downward by threadable advancement of a plurality of screws for squeezing a seal against the collar and a downwardly and outwardly projecting shoulder which causes the seal to expand outward to seal against the inner wall of the pipe. The screws simultaneously bite into the inner wall of the pipe to help secure the coupling assembly in place.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to coupling devices for removable coupling of a plumbing fitting, such as a plug that is inserted into and adjusted to seal non-threaded pipes used in plumbing systems. 
   It is known in the field of plumbing to install cleanout pipes in communication with a waste water pipe system so that objects lodged in the system may be removed through use of cables or other devices introduced into the system through the clean out pipe. Cleanout pipes are typically unthreaded and therefore must be capped at least during pressure testing of the waste water pipe system subsequent to installation. Preferably, the cleanout pipe is capped in a temporary manner so that access may be readily had without having to cut the pipe, as would be necessary for example, with a cap applied with adhesive. 
   Devices for plugging open-ended, non-threaded pipes are known to incorporate O-rings that seal against the inner wall of a pipe when compressed. Such devices, however, generally comprise a two-piece body in which a secondary clamping member is drawn upward or inward toward a primary clamping member by a relatively large screw or bolt to compress an O-ring seal positioned therebetween. The screw extends through apertures in both clamping members. These apertures must be sealed in addition to the seal already required at the gap between the device and the inner wall of the associated pipe. In addition, these devices generally require the use of a relatively large wrench to loosen or tighten the screw or bolt and generally cannot be installed using cordless screwdrivers which are becoming more prevalent in their use. 
   Such prior art seals rely solely on the compression of the seal against the inner surface of the pipe to hold the plug or other fitting in place. It is possible that during pressure testing of the plumbing system that the pressure in the line might be sufficient to blow such a plug out of the end of the pipe. 
   In addition, if it becomes necessary to seal the pipe at a position well within the bore rather than near the open end of the bore it may be possible to modify prior art devices to achieve this aim but according to the common prior art designs such a modification would require providing an elongated clamping member necessary to hold the shoulder and base elements together. 
   There remains a need for an improved coupling assembly for securing plugs and the like in the open end of a smooth walled pipe which is easy to install and forms an airtight seal between the inner wall of the pipe and the outer surface of the coupling assembly and which does not rely solely on the compression of the sealing means for securing the assembly in the open end of a pipe. 
   BRIEF DESCRIPTION OF THE INVENTION 
   A coupling assembly securable in the open end of a pipe comprises a cylindrical body including an upper portion, a medial portion and a shoulder. The medial portion extends below the upper portion and has an outer diameter that is smaller than an outer diameter of the upper portion. The shoulder extends below and projects outward from the medial portion. A plurality of channels are formed in the upper portion and extend from an upper end to a lower end thereof. 
   A pliable seal is disposed around the medial portion above the shoulder. A compression collar is disposed around the cylindrical body above the seal and includes a lower surface that is positioned proximate the seal. A screw is threadingly advanceable through each of the channels in the upper portion of the cylindrical body to engage an upper surface of the collar. The screws are threadingly advanceable downward to push the collar downward and against the seal, compressing the seal between the collar and the shoulder of the cylindrical body causing said seal to protrude radially outward. 
   The screws may be disposed proximate the outer margin of the upper portion of the cylindrical body so that they engage both the cylindrical body around the channels and the inner wall of the pipe, cutting into the inner wall of the pipe as they are driven downward in order to securely hold the coupling assembly within the pipe. This is of particular utility if the coupling assembly is to be used as a plug to seal the end of a plumbing pipe during pressure testing in which case the device may be exposed to pressures that would otherwise tend to cause the seal to fail and/or expel the device from the pipe. 
   Other advantages of the invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example an embodiment of the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a pipe plug showing, in phantom lines, a pipe into which the pipe plug is insertable. 
       FIG. 2  is a front elevation of the pipe plug as shown in  FIG. 1 . 
       FIG. 3  is a top plan view of the pipe plug. 
       FIG. 4  is cross sectional view of the pipe plug taken along line  4 — 4  in  FIG. 3 . 
       FIG. 5  is a cross sectional view similar to  FIG. 4  and showing the pipe plug inserted into the end of a pipe. 
       FIG. 6  is a cross sectional view similar to  FIG. 5  showing a compression collar driven downward to compress and deform a seal to engage an inner wall of the pipe. 
   

   DETAILED DESCRIPTION 
   As required, a detailed embodiment of the present invention is disclosed herein; however, it is to be understood that the disclosed embodiment is 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 now to  FIGS. 1 through 6  of the drawings, there is shown a pipe plug indicated by the reference numeral  1  and incorporating an improved coupling assembly for coupling the pipe plug to the end of a pipe  2  having a pipe bore  3 , such as a cleanout pipe used in plumbing systems. As used herein directional references will be made with reference to the orientation of the pipe plug  1  as shown in FIGS.  1  and  4 – 6  with the terms upper, top and above referring to the direction extending to the top of the page and the terms lower, bottom and below referring to the direction extending toward the bottom of the page. 
   The plug  1  includes a cylindrical body  4  having an upper portion  8 , a medial portion  9  having a reduced outer diameter relative to the upper portion  8 , and a shoulder  10  projecting radially outward and downward from the medial portion  9 . A pliable seal, such as an O-ring  12 , is positioned around medial portion  9 , abutting against the shoulder  10 , and a compression ring or collar  14  is positioned around the medial portion  9  above the O-ring  12 . Screws  15  extending through channels or grooves  16  formed in the upper portion  8  of the cylindrical body  4  are threadingly advanceable downward to drive the compression collar  14  against the O-ring  12 , to compress the O-ring  12  between collar  14  and shoulder  10  causing the O-ring  12  to protrude radially outward. When the plug  1  is installed in the end of a pipe  2 , the outward protrusion of the O-ring  12  causes a seal to form between the O-ring  12 , the inner surface of the pipe  2  and the outer surface of the cylindrical body  4 . 
   As shown in the drawings, the cylindrical body  4  is hollow with a bore  18  extending into the cylindrical body  4  from a lower end  19  thereof. A closure member or wall  22  is connected to the cylindrical body and extends across the bore  18  at an upper end  23  of the cylindrical body  4  closing the upper end  23 . It is foreseen that the closure member  22  could be positioned at other positions relative to the cylindrical body  4  including proximate the lower end  19  thereof or anywhere between the lower end  19  and upper end  23 . If the closure member  22  is positioned at the lower end  19  of cylindrical body  4 , the bore  18  would be described as extending into the cylindrical body  4  from the upper end  23 . 
   A mounting flange  27  projects radially outward from the cylindrical body  4 , preferably adjacent the upper end  23  thereof for use in supporting the plug  1  on the end of a pipe  2 . Referring to  FIGS. 5 and 6 , the outer diameter of the mounting flange  27  is sized to be larger than the inner diameter of the pipe  2  and approximately equal to the outer diameter of the pipe  2 . As illustrated, the mounting flange  27  projects radially outward from the upper end  23  of cylindrical body  4  to engage the end of the pipe  2  to be sealed thus preventing over insertion of the plug  1  into the pipe bore  3 . 
   The closure member  22 , positioned at the upper end  23  of the cylindrical body  4  generally presents a flat, planar surface with the cylindrical body upper end  23  and the flange  27 . The flange  27  is typically relatively thin to present a relatively low profile above the end of a pipe  2  to which the plug  1  is secured. The cylindrical body  4  could have a solid core, but the hollow core facilitates molding, conserves material and reduces weight. 
   The diameter of the upper portion  8  of the cylindrical body  4  is sized to be slightly smaller than the inner diameter of the pipe  2  in which the plug  1  is to be installed. The medial portion  9  may be described as being defined by a recess formed in the cylindrical body  4  below the upper portion  8 . The diameter of the medial portion  9  is reduced relative to the upper portion  8  to accommodate the compression collar  14 . In the embodiment shown, the compression collar  14  comprises a split annular ring that fits around the medial portion  9  of the cylindrical body  4 . The collar  14  is approximately equal in thickness to the depth of the recess forming the medial portion  9  of cylindrical body  4  so that an outer surface  30  of the collar  14  generally extends flush with an outer surface  32  of the upper portion  8 . 
   The shoulder  10  flares or slopes downward and radially outward from a lower end of the medial portion  9  and may generally be described as being formed by the same recess that defines the medial portion  9 . The outer diameter of the lower edge of the shoulder  10  typically approximates the diameter of the upper portion  8  of the body  4 . 
   The cylindrical body  4 , the closure member  22  and the mounting flange  27  may be constructed as one piece or may be formed from individual pieces secured together by gluing, welding, heat bonding or the like. Typically, the cylindrical body  4 , closure member  22  and flange  27  are formed of a resilient, yet relatively light weight material such as plastic that is shaped in a mold. An appropriate plastic material commonly used to form plumbing fixtures includes polyvinyl chloride. 
   The compression collar  14  is typically formed separately from the body  4  and may be split to include a gap  36  so that the collar  14  can be opened at the gap  36  to fit around the medial portion  9  of the body  4 . Alternatively, in the case where the sections of the cylindrical body  4  are formed separately, the compression collar  14  may be slipped onto the medial portion  9  prior to attachment of the shoulder  10 . 
   The seal  12  shown comprises a pliable, rubber O-ring disposed around the medial portion  9  of the cylindrical body  4  adjacent and overlapping with the shoulder  10 . As shown in FIGS.  1  and  4 – 6 , the seal  12  is generally located at the juncture between the medial portion  9  and the shoulder  10 , which as used herein may be described as extending around the medial portion  9  and above or upward from the shoulder  10 . 
   In the embodiment shown, the channels or grooves  16  for receiving the screws  15  are generally formed as semi-cylindrical grooves  16  extending into the upper portion  8  of the cylindrical body  4  from the outer surface  32  thereof. The grooves  16  extend from an upper end to a lower end of the cylindrical body upper portion  8  and open into the recess defining the medial portion  9  of the cylindrical body  4 . Holes  40  are formed in the pipe plug  1  proximate to the interface between mounting flange  27  and the upper end of the cylindrical body upper portion  8 . Holes  40  extend in axial alignment with the grooves  16  formed in the outer surface  32  of the upper portion  8  of body  4 . 
   The grooves  16  are typically formed to be smooth walled. The diameter of the grooves  16  is sized smaller than the diameter of the screws  15  such that the threads of the screws  15  bite into and engage the portion of the cylindrical body upper portion  8  surrounding the grooves  16  when the screw  15  is driven through one of the holes  40  with the pipe plug  1  positioned in a pipe  2  that is just slightly larger in internal diameter than the outer diameter of the cylindrical body  4 . Simultaneously, the thread of each screw  15  also bites into the inner surface of the pipe  2  as the screw  15  is driven downward through hole  40  and along groove  16 . 
   In operation, the plug  1  is inserted into the end of a pipe  2 , shoulder  10  first, until the flange  27  abuts against the end of the pipe  2 . Screws  15  are then driven downward through holes  40  and along grooves  16 . As each screw  15  is rotated by a driver, its thread bites into the upper portion  8  of the body  4  around the associated groove  16  and simultaneously into the inner surface of the pipe  2  securing the plug  1  to the pipe  2 . When the ends of the screws  15  are driven past the lower end of the cylindrical body upper portion  8 , the ends of the screws  15  contact an upper surface of the compression collar  14 . 
   As the screws  15  are driven yet further downward the ends thereof press against the compression collar  14  forcing the collar  14  downward to press against and compress the seal  12  between the collar  14  and shoulder  10 . As the seal  12  is compressed downward against the shoulder  10 , it tends to roll slightly downward along the sloped surface of the shoulder  10 , thereby expanding outward. In addition, as the seal  12  is compressed it is flattened and expanded laterally so that the outer edge of the seal  12  contacts the inner wall of the pipe  2 . This forms a tight seal capable of withstanding increased liquid or gaseous pressure. In a preferred embodiment, the lower ends of the screws  15  are preferably blunt to act to drive the compression ring downward instead of biting into the compression ring  14  and drawing it upward away from the seal  12 . 
   Use of the threaded fasteners  15  facilitates installation of the plug  1  in that the installer may use a commonly available power screw driver to tighten or loosen the threaded fasteners  15  to install or release the plug  1  from the pipe  2 . Driving the screws  15  through holes  40  and along grooves  16  acts to both compress the seal  12  and threadingly couple the plug  1  to the inner surface of the pipe  2  providing a relatively strong and air-tight connection between the plug  1  and the pipe  2 . 
   It is to be understood that while certain forms of this invention have been illustrated and described, it is not limited thereto except insofar as such limitations are included in the following claims and allowable equivalents thereof. For example, although the grooves or channels  16  are shown as smooth walled, it is anticipated that the grooves could be threaded. In addition, it is foreseen that the grooves could extend completely within the cylindrical body upper portion  8  such that the screws would not be exposed to or threadingly engage an inner surface of the pipe  2 . 
   It is also foreseen that the coupling assembly could be utilized for plumbing fittings or devices other than plugs. For example, the device as shown could be utilized without the closure member  22  and with a thread formed on the inner surface of the bore  18  to permit use of the coupling assembly to supply a threaded coupling for an otherwise smooth walled pipe, without permanently threading the inner surface of the pipe (except for any threading caused by the screws  15  if exposed to the inner surface of the pipe  2 ). Alternatively, using the device without the closure member  22 , the inner surface of the bore  18  could be formed to function as a glue hub to facilitate gluing additional items thereto, without permanently adhering such an element directly to the pipe  2 . 
   It is also foreseen that the closure member  22  could be connected to the cylindrical body  4  by a thin web of material to facilitate separation of the closure member from the cylindrical body  4  if so desired. Alternatively, the closure member could be formed with some other form of removable structure to create an opening through the closure member  22 .