Abstract:
A connector for connecting lengths of tubing in an end to end relation, the connector comprises a central body comprising first and second cooperating members operatively associated with a mechanism for moving the cooperating members in a direction transverse to the longitudinal axis of the connector and wedge members, the wedge members surrounding the central body and resting against the central body so that when the cooperating members are caused to move apart, the wedge members are urged outwardly to uniformly engage the interior of a tube to be connected.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a connector and in particular, a connector for interconnecting the ends of adjacent lengths of tubing and a structural member formed from interconnected tubing and the connector. 
   BACKGROUND AND SUMMARY OF THE INVENTION 
   Structures formed from interconnected lengths of tubing are known. For example, tubing may be variously connected to provide a temporary modular structure for supporting a sign or a banner.  It is advantageous if the lengths of tubing are easily interconnected and provide a structure that is rigid and adapted to be readily disassembled for later reuse. 
   A frequent problem is that repeated assembly and disassembly of the tubing causes wear to the structural components. In particular, a connector inserted within and then removed from the ends of the tubes causes wear to the interior of the tube. Eventually, the wear to the interior of the tube becomes so great that the connector cannot compensate for variances in wall thickness and a rigid connection with the tube is no longer possible. Variances in tube thickness may also result during manufacture and similarly contribute to a connection problem. Even small differences in the thickness of tube to be connected can result in a poor connection and insufficient rigidity of the interconnected structure. 
   Expandable connectors adapted to be inserted within the interior of adjacent tubes are known however these devices are not satisfactory. In particular, these devices do not provide a high degree of surface contact between the connector and the interior of the tube to be connected and only provide contact at discrete locations. As is apparent, such connections do not result in a sturdy and rigid connection along the entire surface area of the connector. Second, the prior art connectors are designed to bite into the interior wall of the tube thereby resulting in excessive wear to both the connector and the tube wall. Third, expandable prior art connectors do not apply contact pressure against the tube in a uniform manner. This  results in a less than rigid connection and causes uneven wear to the connected tube. 
   In view of the above, the present invention provides a connector for tubing adapted to compensate for wear or variances in thickness of the tubing wall and to provide a circumferentially uniform contact force against the tube being connected as well as to provide a large surface area of contact between the connector and the tube. In addition, the connector of the present invention has an uncomplicated design providing a reliable connector that is easily disassembled for servicing or repair. 
   In summary, the present invention is directed to a connector for tubing comprising a central body having a longitudinal axis extending from a first end to a second end, the central body comprising first and second cooperating members, an expansion mechanism for selectively moving the first and second cooperating members in a direction transverse to the longitudinal axis of the central body and at least first and second wedge members surrounding the central body in an equidistant manner and resting against the central body from about the first end to the second end so that when the first and second cooperating members are moved apart by the expansion mechanism, the wedge members are urged in a direction outwardly from the central body along the longitudinal axis thereof to engage against the interior of a tube to be connected.  

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is perspective view showing the connector of the present invention and two sections of tubing to be connected; 
       FIG. 2  is a perspective view of the connector according to the present invention without the adjustment and locking screws; 
       FIG. 3  is a exploded view of the connector according to the present invention; 
       FIG. 4  is a top plan view of the connector according to the present invention interconnecting two sections of tubing with a portion of one of the tubes broken away; 
       FIG. 5  is a cross-section view of the connector shown in  FIG. 1  and taken along lines  5 — 5 ; and 
       FIG. 6  is a cross-sectional view of the connector shown in  FIG. 4  and taken along lines  6 — 6 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The connector C of the present invention is shown in  FIGS. 2 and 3  and in  FIGS. 1 and 4  with two sections of tubing T. Connector C is adapted to be inserted within the interior of adjacent sections of tubing T to connect the tubing in a manner as will be explained below. 
   The connector C includes a central portion or body  2 . The central body  2  comprises two cooperating members  4  and  6  shown to be mirror images of each other. Each of the cooperating members  4  and  6  have a generally wedge shaped cross-section and in at least one embodiment, the wedge shaped cross-section is an  isosceles trapezoid. Central body  2  is provided with four cam surfaces  8 ,  10 ,  12  and  14 . Cam surfaces  8  and  10  are associated with cooperating member  6  and cam surfaces  12  and  14  are associated with cooperating member  4 . 
   Cooperating member  6  includes threaded passageways  16  and  18  that extend through the interior of the cooperating member  6 . Threaded passageways  16  and  18  are coaxially aligned with concave regions or portions  20  and  22  provided on cooperating member  4 . 
   Wedge members  24 ,  26 ,  28  and  30  surround central body  2  in an equidistant manner and rest against the central body along central body cam surfaces  8 ,  10 ,  12  and  14  respectively. Each of the wedge members are shown to have a generally triangular cross-section shape defining exterior contact surfaces. For example, in  FIG. 3  wedge member  28  is shown to include exterior contact surfaces  32  and  34 . The remaining wedge members are provided with similar contact surfaces. Each of the wedge member are also shown to include an interior contact surface. For example, in  FIG. 3  wedge member  26  is shown to include an interior contact surface  36  that rests against central body  2 . The remaining wedge members are provided with similar interior contact surfaces. 
   As best shown in  FIG. 3 , each wedge member is provided with a channel section coextensive with the channel section of an adjacent wedge member so that connector C includes first and second channels  38  and  40  ( FIGS. 2 and 4 ) disposed at opposite ends of the connector C. An elastomeric O-ring  50  ( FIGS. 1 ,  2  and  4 ) is fitted within each of the first and second channels  38   and  40  to maintain the wedge members in contact and alignment with central body  2  and the entire connector in an assembled position. Wedge members  28  and  30  are provided with widened regions  44  and  42  that cooperate to provide open regions  46  and  48  through which the threaded screws  52  and  54  of the connector C will respectively pass. 
     FIG. 1  illustrates alignment of the connector C when inserted within two adjacent sections of tubing T to be connected. Each end of tubing T is provided with a bore  56  having a size sufficient to allow one of screws  52  and  54  to pass through.  FIG. 5  illustrates the position of connector C within a section of tube T before interconnection and showing a gap extending between the interior of the tube T and the outer perimeter of the connector C.  FIG. 4  illustrates the connector C interconnecting two sections of tubing T. Each of screw  52  and  54  is rotated (via hex wrench H shown in  FIG. 1 ). As the screw advances through the threaded passage  16  of cooperating member  4 , an opposite end of the screw is pressed against cooperating member  6  at concave region  22  to cause separation of the cooperating members in a direction transverse to the longitudinal axis of the central body  2  and as indicated by arrow  58  in  FIG. 6 . Cam surfaces  8 ,  10 ,  12  and  14  simultaneously cause respective wedge members  24 ,  26 ,  28  and  30  to move outwardly and in the direction of arrows  60  shown in  FIG. 6  along the entire length of the connector C. As a result, the exterior contact surfaces of each wedge member will apply pressure against the interior wall of the tubing and in a manner so as to uniformly engage the  interior surface of the tubing T ( FIGS. 4 and 6 ) to connect adjacent sections of tubing T. As is apparent, because the adjustment screws extend through a bore  56  of each tube, they provide locking engagement to the tubes that is supplemental to that provided by the wedge members against the interior of the tube. To disengage, the screw is rotated in a direction opposite to that during engagement until it is removed from the connector C and bore  56  of tubing T. 
   If the interior wall of the tubing becomes worn away causing the interior diameter to increase, the user increasingly expand the connector until a sufficiently rigid connection is achieved and the variance is compensated for. In addition, because the wedge members do not bite into the tube along discrete location but instead contact a large surface area of the tube, a rigid and strong connection will result. 
   Various modifications of the preferred embodiment described above are within the scope of the present invention. The connector may be constructed from aluminum extrusion or other metals, composites, plastics or any rigid material having properties well adapted to the end use of the structure. As is apparent, the screws may be modified to provide other than a hex head. The screws may even be replaced with another mechanism adapted to convert rotational movement to translational movement (rotary to linear) so long as the mechanism selected is adapted to move the cooperating members to move apart. While the embodiment disclosed above permits disassembly and reuse of the connected structure, the connector may be modified to remain  fixed following interconnection. The O-ring may be modified so long as it continues to provide the necessary retention forces that enable the connector to expand and contract and remain assembled. Although the tubing is shown to have a square cross-section, the present invention is readily adapted for use with tubing having a circular cross-section. In that embodiment, the exterior contact surfaces of the wedge members are reshaped in a suitable manner and at least two wedge members are necessary. Other configurations of the exterior contact surfaces are within the present invention. Furthermore, the wedge members may be coextensive with the full length of the central body or modified in a manner to not extend the full length of the connector in applications where such contact with a tube would be desirable. 
   While this invention has been described as having a preferred design, it is understood that it is capable of still further modifications and uses and/or adaptations of the invention following in general the principle of the invention and including such departures from the present disclosure as come within the known or customary practice in the art to which the invention pertains and as may be applied to the central features hereinbefore set forth and fall within the scope of the invention or limits of the claims appended hereto.