Abstract:
A coupler for a low pressure piping system has a hollow metal tube terminating in a pair of end portions defining open ends for slidably receiving and joining together sections of other metal tubes in a substantially air tight relationship. Slots are formed in at least one of the end portions to aid in the crimping of the hollow metal tube by an annular clamp. A radial flange is formed adjacent the end portion and receives an annular seal therein. A stop for limiting the insertion of a tube section into the end of the hollow metal tube is formed on the inside of the coupler adjacent the radial flange opposite the slots. The annular clamp encircles the slots and is tightened to clamp the end portions to form metal to metal contact between the metal tubes and to form a seal between the annular seal and both metal tubes.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This is a standard utility patent based on provisional patent Ser. No. 60/396,162 filed Jul. 15, 2002. 

   BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The invention relates to an improved coupler for a piping system. More particularly, the invention relates to a coupler for a low pressure or vacuum piping system for transporting materials with air. Specifically, the invention relates to a coupler generally made of a hollow metal tube and configured to receive another metal tube and clamp down on the other tube to create metal to metal contact between the two tubes and a seal between the tubes, and to an improved annular seal inserted in the hollow metal tube. 
   2. Background Information 
   In the past, vacuum and pressure pipes which were used for transporting material, such as tobacco or fine dust from wood shops or flour mills, etc. have been held together with coupling systems. However, such dust has a tendency to explode. Therefore, metal straps have been used in couplings having rubber gaskets to assure that metal to metal contact exists for grounding. These metal straps add cost to the coupler and can also push seals out of place during installation. Thus, there exists a need to maintain metal to metal contact between a coupler and the joined piping without the need for separate metal grounding straps. 
   In high vibration areas, piping can vibrate out of a coupling, breaching the system. Thus, creating a strong clamping bond between the coupler and piping in the system is of primary concern. 
   In addition, a reliable and airtight seal is required under low pressure or vacuum conditions to ensure that the material flowing through the pipes does not leak out and that an effective and efficient flow is maintained. Thus, the creation of an airtight seal is important. 
   Also, there is a need for a coupler that is easily and quickly installed, and which reduces or eliminates the need for training for installing the coupler. 
   Thus, the need exists for a coupler for a low pressure piping system that is easy to install, which will maintain metal to metal contact throughout the system without the use of metal straps, which will remain intact in high vibration areas, and which will maintain an airtight seal under low pressure conditions. 
   BRIEF SUMMARY OF THE INVENTION 
   Advantages of the invention include providing a coupler for a low pressure piping system which is seamless, thus reducing the chance of leakage and increasing the coupler&#39;s strength. 
   A further feature of the coupler is to provide slots adjacent the open end of the coupler to facilitate the clamping of the coupler onto a tube. 
   Another feature of the coupler is to provide a radial flange into which is inserted an annular seal to provide an airtight seal. 
   Still another feature of the coupler is to provide a stop to ensure the proper amount of insertion of a metal tube into the coupler without the need for measuring or estimation. 
   Yet another feature of the coupler is to provide improved gripping strength between the coupler and tubes in the system by the use of metal to metal clamping. 
   Another feature of the coupler is to maintain metal to metal contact throughout the system for electrical grounding without the need for separate grounding straps. 
   Another feature is a coupler which is relatively light weight. 
   Yet another feature of the coupler is the ability to maintain an effectively airtight seal under low pressure or vacuum conditions. 
   A still further feature of the coupler is that it can be simply and quickly installed. 
   Another feature of the coupler is that it eliminates tightening instructions and thus reduces the need for installation training. 
   A further advantage is a coupler that requires only one or two bolts to be tightened to clamp the coupler to a metal tube, and each bolt need be tightened only once. 
   Another feature is a coupler in which one end of the coupler may be installed independently of the other end, allowing the clamping of the coupler to a metal tube prior to installation. 
   Yet another feature of the coupler is the use of seals situated so they will not fall out during routine handling. 
   Another advantage is a coupler for a low pressure piping system of simple construction, which achieves the stated features in a simple, effective and inexpensive manner, and which solves problems and satisfies needs existing in the art. 
   These and other features and advantages of the invention are obtained by the coupler for a low pressure piping system of the present invention, the general nature of which may be stated as including a hollow metal tube terminating in a pair of end portions, defining open ends, at least one of said end portions being formed with a plurality of slots; a radial flange formed in the tube adjacent said one end portion, said flange having an inner surface; an annular seal having an outer surface complimentary with the inner surface of said radial flange, and seated in said flange; and an annular clamp encircling the slots. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the invention, illustrative of the best modes in which applicant has contemplated applying the principles, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims. 
       FIG. 1  is a perspective view of the coupler of the present invention; 
       FIG. 2  is a perspective view of the coupler without the annular clamps; 
       FIG. 3  is a sectional view of the coupler taken on line  3 — 3 ,  FIG. 2 ; 
       FIG. 4  is a perspective view of the coupler showing connecting tubes in fragmentary inserted in both ends thereof; 
       FIG. 5  is an exploded perspective view of the coupler shown in  FIG. 4 ; 
       FIG. 6  is a longitudinal sectional view of the coupler taken on line  6 — 6 ,  FIG. 4 ; 
       FIG. 7  is an end view of the coupler shown in  FIG. 1 ; 
       FIG. 8  is a schematic view of the coupler joining together several tube sections; 
       FIG. 9  is a fragmentary top plan view of a second embodiment of the present invention; 
       FIG. 10  is a fragmentary perspective view of the embodiment shown in  FIG. 9 ; 
       FIG. 11  is a fragmentary perspective view of a third embodiment of the present invention; 
       FIG. 12  is a side elevational view with portions cut away and shown in section of a fourth embodiment of the present invention; 
       FIG. 13  is an enlarged view of the encircled portion of  FIG. 12 ; 
       FIG. 14  is a side elevational view with portions cut away and shown in section of a fifth embodiment of the present invention; 
       FIG. 15  is an enlarged view of the encircled portion of  FIG. 14 ; 
       FIG. 16  is a side elevational view with portions cut away and shown in section of a sixth embodiment of the present invention; and 
       FIG. 17  is an enlarged view of the encircled portion of FIG.  16 . 
   

   Similar numerals refer to similar parts throughout the drawings. 
   DETAILED DESCRIPTION OF THE INVENTION 
   The coupler for a low pressure piping system of the present invention is indicated generally at  1 , and is shown particularly in  FIGS. 1-8 . Coupler  1  includes a substantially cylindrical seamless metal tube  2  having end portions  4 , a reduced diameter central portion  3  which is connected to end portions  4  by larger diameter portions  7 . Tube  2  further includes a central longitudinal axis  5 , an inner surface  6 , an outer surface  8 , and a pair of open ends  10  for slidably receiving sections of metal tubes  13  therein as shown in  FIGS. 4 and 6 . Open ends  10  preferably terminate in outwardly flared peripheral edges  11 . A plurality of circumferentially spaced slots  12  are formed in end portions  4  adjacent open ends  10 . An outwardly extending radial flange  14  ( FIG. 3 ) is formed between each end portion  4  and each larger diameter portion  7  and has a generally U-shaped inner surface  16 . Slots  12  are elongated and extend parallel to axis  5  from adjacent open ends  10  partially into radial flanges  14 . An elastomeric annular seal  18 , such as a rubber O-ring, is seated in each U-shaped surface  16  of radial flange  14 . Stops  20  ( FIG. 3 ) are formed on inner surface  6  of tube  2  at the junctions between reduced diameter center portions  3  and adjacent tube portions  7 . 
   An annular clamp, indicated generally at  22 , is mounted on each end portion  4  and encircles slots  12 . Each clamp  22  includes a threaded bolt  24 , a threaded nut  26 , a washer  28  and an annular band  30 . Band  30  is formed from substantially flat sheet metal and terminates in outwardly extending opposed and spaced tabs  32  which have aligned holes  31  formed therein for receiving bolt  24 . Band  30  has a width extending substantially from radial flange  14  to flared edge  11  of end portion  4  and substantially covers slots  12 . 
   Coupler  1  is configured to link sections of metal tubes  13  in a low pressure piping system, as shown in  FIGS. 4 ,  5 ,  6  and  8 . Each metal tube  13  is inserted into open end  10  until an end  15  of metal tube  13  rests against stop  20 . Stop  20  ensures that metal tube  13  is inserted beyond annular seal  18  and ensures that the correct amount of overlap exists between the coupler and tube sections. Slots  12  facilitate the crimping of tube  2  when bolt  24  and nut  26  are screwed together to tighten annular clamp  22 , which holds tubes  2  and  13  firmly together. The tightening of annular clamp  22  serves two further purposes. First, an airtight seal is formed between seal  18  and tubes  2  and  13  under low pressure conditions. Second, metal-to-metal contact is created between metal tubes  2  and  13 , which contact creates an effective ground for any electrical current or static electricity generated by the materials moving through the tubes and couplers. 
   It will be appreciated that the various structures creating the coupling function can be included in only one end of tube  2 . That is, only one end of tube  2  need include end portion  4 , radial flange  14 , seal  18 , stop  20  and clamp  22 . Thus, the scope of the invention encompasses coupler  1  wherein a metal tube  13  can be inserted into each open end  10  and also encompasses a coupler in which only one open end receives a metal tube  13  while the other end itself can be inserted into the open end of another coupler.  FIG. 8  shows coupler  1  one linked to a pair of the latter type of coupler, which in this case also include arcuate tubes  2 A.  FIG. 8  shows the arcuate tubes having end portions  4 A on one end only. Further, the invention contemplates a more complex metal tube that may be branched, such as a Y-shaped metal tubing, wherein there are more than two ends, any or all of which could be configured to function as a coupler. 
   It will be further appreciated that annular seal  18  could be formed of a suitable material other than rubber. Also, coupler  1  will function without stop  20 , although stop  20  is helpful in facilitating installation of a piping system. Stop  20  may have various configurations, such as dimples or a radial flange extending inwardly from inner surface  6  of tube  2  or other suitable configurations. Clamp  22  can also have various configurations which may not include a threaded bolt and threaded nut. 
   A second embodiment of the present invention is shown in  FIGS. 9-10  and includes a coupler  101 . Coupler  101  is similar to coupler  1  in many respects, except that V-shaped slots  112  replace elongated slots  12 . Slots  112  have the point of the V facing away from end  10  and toward radial flange  14 . 
   A third embodiment of the present invention is shown in FIG.  11  and includes a coupler  201 . Coupler  201  is similar to coupler  1 , except there is no flared peripheral edge  11  defining open end  10 , and slots  212  have open ends  213  that communicates with open end  10  and do not extend into radial flange  14 . 
   A fourth embodiment of the present invention is shown in  FIGS. 12-13  and includes a modified coupler  301 . Coupler  301  is similar to coupler  1 , except that it has a modified radial flange  314  and annular seal  318 . Annular seal  318  in cross-section is substantially trapezoidal, having a long parallel side  320  and a short parallel side  322 , and a pair of tapered sides  324  and  326 . Sides  320  and  322  extend parallel to axis  5  when seated within a complementary shaped interior of flange  314 . Seal  318  has a hollow interior  330  and includes a blade  332  which extends medially and perpendicularly from long parallel side  320  inwardly therefrom. Blade  332  has elongated parallel sides  334  which extend perpendicularly from side  320  and has a flat terminal short edge  336  which is parallel to side  320  (FIG.  13 ). 
   Radial flange  314  is generally U-shaped in cross section and has a bottom  338  and a pair of tapered sides  340  and  342 . Bottom  338  is parallel to axis  5 , and sides  340  and  342  extend obliquely from bottom  338 . 
   A fifth embodiment of the present invention is shown in  FIGS. 14-15  and includes a modified coupler  401 . Coupler  401  is similar to coupler  1 , except that it has a modified radial flange  414  and annular seal  418 . 
   Annular seal  418  in cross section is generally W-shaped and has a pair of tapered sides  420  and  421 , and outer and inner surfaces  422  and  424 , respectively. Outer surface  422  has a pair of flat portions  426  and  428  each communicating with an intermediate concavity  430 . Flat portions  426  and  428  each communicate with one of tapered sides  420  and  421  and extend parallel to axis  5  when seated within an interior of flange  414 . The interior of flange  414  is complementary with tapered sides  420  and  421  and flat portions  426  and  428 . Inner surface  424  has a pair of rounded portions  432  and  434  each communicating with an intermediate concavity  436  and with one of tapered sides  420  and  421 . Each surface  432  and  434  is generally opposite one of the flat portions  426  and  428 . Intermediate concavity  430  is generally opposite intermediate concavity  436 . A pair of hollow interiors  438  and  440  are formed in seal  418 , each of said hollows interior being adjacent one of the rounded portions  432  and  434 . 
   Radial flange  414 , like radial flange  314 , is generally U-shaped in cross section and has a bottom  442  and a pair of tapered sides  444  and  446 , with bottom  442  being parallel to axis  5 , with sides  444  and  446  extending obliquely from bottom  442 . 
   A sixth embodiment of the present invention is shown in  FIGS. 16-17  and includes modified coupler  501 . Coupler  501  is similar to coupler  1 , except that it has a modified radial flange  514  and annular seal  518 . 
   Annular seal  518  is a hybrid of annular seals  318  and  418 . Annular seal  518  in cross section is generally W-shaped and has a pair of tapered sides  520  and  521 , an outer surface  522 , and an inner surface  524 . Surface  522  has a pair of flat portions  526  and  528  each communicating with an intermediate concavity  530 . Flat portions  526  and  528  each communicate with one of tapered sides  520  and  521  and extend parallel to axis  5  when seated within an interior of flange  514 , said interior being complementary with tapered sides  520  and  521  and flat portions  526  and  528 . Inner surface  524  has a flat portion  531  and a rounded portion  532  which communicates with tapered side  520  and flat portion  531 . Rounded portion  532  is generally opposite flat portion  526  and flat portion  531  extends parallel to axis  5  when seated within the interior of flange  514 . A blade  534  extends perpendicularly inwardly from flat portion  531 . Blade  534  has elongated parallel sides  536  which extend perpendicularly from flat portion  531  and has a flat terminal short edge  538  which is parallel to flat portion  531  (FIG.  17 ). Seal  518  has a hollow interior  540  adjacent convexity  532 . 
   Radial flange  514 , like radial flanges  314  and  414 , is generally U-shaped in cross section and has a bottom  542  and a pair of tapered sides  544  and  546 . Bottom  542  is parallel to axis  5 , and sides  544  and  546  extend obliquely from bottom  542 . 
   As described herein, the coupler of the present invention is simplified, provides an effective, safe, inexpensive, and efficient device which achieves all the enumerated features and advantages, provides for eliminating difficulties encountered with prior devices, and solves problems and obtains new results in the art. 
   In the foregoing description, certain terms have been used for brevity, clearness and understanding, but no unnecessary limitations are to be implied therefrom beyond the requirement of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, the description and illustration of the invention is by way of example, and the scope of the invention is not limited to the exact details shown or described. 
   Having now described the features, discoveries and principles of the invention, the manner in which the coupler is constructed and used, the characteristics of the construction, and the advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangements, parts and combinations are set forth in the appended claims.