Abstract:
A device for the threaded connection of tubular members, particularly as used in the petroleum industry, which provides both the full strength and near full internal diameter of typical oilfield tubular threaded connections, with the ability to securely join two cylindrical members with eccentric internal connections.

Description:
[0001]    Applicant claims the benefits of provisional application Ser. No. 61/888,106, filed Oct. 8, 2013. The present invention introduces a novel structure for connecting cylindrical parts having internal, eccentrically positioned parts requiring engagement. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Field of the Invention 
         [0003]    In a world where mechanization is state-of-the-art, various mechanical parts are necessarily connected with one another to create a path for the flow of energy, for example. Typical among such parts are cylindrical parts which, when connected, create a path for the uninterrupted flow of fluids, electricity, and other such elements. 
         [0004]    For myriad reasons, the connection between cylindrical parts, even such parts which are of identical diameter, can be a difficult task. Not surprisingly, such connections can often be found at the point where access is severely limited and the ability to get a wrench or other tool on a connector is not only difficult, but in some instances, perhaps impossible. 
         [0005]    Overview of the Prior Art 
         [0006]    Joining cylindrical members, such as pipes or cylindrical housings, is usually done in one of three methods: flange connection, that is where a flange is formed or otherwise positioned at the connection point on the cylindrical members to be joined and then the flanges themselves are joined together. Also there may be a threaded connection, and, finally, the use of welds is used where it is safe to do so, and there is no need to get into the cylindrical members for maintenance and repair once they are joined. 
         [0007]    However, if there are internal elements that must be joined, and those elements are not concentric within the cylindrical parts being joined, an obvious problem has been created. The prospect of using a threaded connection is obviously vitiated. Otherwise stated, if there are internal components, the connections of which are eccentric, relative rotation of the cylindrical members to be joined is not feasible, and use of a conventional threaded connection is not possible. In those cases, either a flange connection is used, or the two members are welded. 
       SUMMARY OF THE INVENTION 
       [0008]    As will become apparent from a reading of the detailed description of the present invention, it is a singular objective of the present invention to provide to industry a very simple and straightforward device for effecting a connection between cylindrical casings, or the like, including internal ports being also interconnected within very restricted and limited space. 
         [0009]    It is a further objective of the present invention, related to the foregoing, to provide an effective seal between cylindrical parts in limited spaces, which seal is capable of being unsealed for maintenance, replacement or repair. 
         [0010]    There are certain situations where the cylindrical members have a restricted outer diameter, such as oil field downhole assemblies, which usually must fit snugly within boreholes or casing, and a conventional external flange is not feasible. In these cases, an internal flange can be used. This type of flange is commonly used for oilfield downhole producing equipment. The disadvantage of such a flange connection is the significant restriction in inner diameter at the neck of the flange. 
         [0011]    If the internal components of the members to be joined have eccentric connections require a greater inside diameter than allowed by the internal flange, one is forced to resort to a welded connection. However, welded connections may not be either feasible, due to temperature sensitivity of the equipment or components inside the housing, or desirable due to the resulting unit being of a greater length than can be easily handled. Welding also changes the metallurgy of the housing material, which can weaken it or make it more vulnerable to corrosion. 
         [0012]    The present invention provides a method to securely join two cylindrical members via a threaded connection, while allowing the eccentric components connections. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  shows a cross-section through a typical internal flange connection between downhole components of an electrical centrifugal pump; 
           [0014]      FIG. 2  is a perspective view of the ends of two cylindrical members to be joined, showing the eccentric location of components to be connected during the process; 
           [0015]      FIG. 3  is a perspective side view of the same two cylindrical members in position to be joined; 
           [0016]      FIG. 4  is a side view of the doubly threaded coupling, with a window in the coupling showing the internal threads; 
           [0017]      FIG. 5  is a perspective side view of the doubly threaded coupling, showing the right-hand threads on the inside right surface of the coupling; 
           [0018]      FIG. 6  is a perspective view of the two cylindrical members with the coupling (shown semi-transparent) positioned for joining the two members together; 
           [0019]      FIG. 7  is a perspective view of the two cylindrical members nearly completely joined via the rotation of the doubly threaded coupling; 
           [0020]      FIG. 8  is a perspective view of the two cylindrical members completely joined by the coupling; 
           [0021]      FIG. 9  is a side view of the two cylindrical members partially connected, with a window in the threaded coupling revealing the position of the infernal components; 
           [0022]      FIG. 10  is the same side view as shown in  FIG. 9 , with the two cylindrical members completely connected, with a window in the threaded coupling showing the final position of the internal components; 
           [0023]      FIG. 11  is a perspective view of the ends of two cylindrical members to be joined, similar to  FIG. 2 , showing the O-ring sealing elements of each of the cylindrical members; 
           [0024]      FIG. 12  is a side view of the doubly threaded coupling for joining the cylindrical members shown in  FIG. 9 , with a window in the threaded coupling revealing the position of the internal components; 
           [0025]      FIG. 13  is a side view of the  FIG. 11  embodiment showing the two cylindrical members partially connected, with a window in the threaded coupling revealing the position of the internal components; 
           [0026]      FIG. 14  is the same side view as shown in  FIG. 13 , with the two cylindrical members completely connected, with a window in the threaded coupling showing the final position of the internal components; 
           [0027]      FIG. 15  is a side view of two cylindrical members to be joined, where the outer diameters of the perspective members are not equal; and, 
           [0028]      FIG. 16  shows the  FIG. 15  embodiment fully connected, with a window in the threaded coupling showing the position of the threaded portion of the cylindrical members. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0029]    The present invention has a particular, although not exclusive, beneficial use for those in the oil patch. By way of example, there are many situations where cylindrical members to be joined have a restricted outer diameter due to limited space within a borehole or casing, and the use of a conventional external flange connection is not feasible. In these cases, an internal flange can be used. This type of flange, shown in  FIG. 1 , is commonly used for oilfield downhole producing equipment. The disadvantage of such a flange connection is the significant restriction in inner diameter at the neck of the flange. 
         [0030]    If the internal components of the cylindrical members to be joined have eccentric connection, offset from the centerline of the cylindrical members, and require a greater internal diameter than allowed by the internal flange, oilfield workers today, until the advent of the present invention, have been forced to resort to a welded connection. However, welded connections may not be either feasible, due to temperature sensitivity of the equipment or components inside the housing, or desirable due to the resulting unit being of a greater length than can be easily handled. Welding also changes the metallurgy of the housing material, which can weaken it or make it to more vulnerable to corrosion. 
         [0031]      FIG. 1  is a representation of a typical internal flange arrangement that is in current use in many production wells. Briefly, cylindrical members  20  and  22  are joined at flanges  24  and  25  by fasteners  26 . Note the great restriction in the diameter of the connecting neck  27  and  29  between the two cylindrical members. 
         [0032]      FIGS. 2 through 10  show, in stark contrast, the current invention.  FIG. 2  shows the ends of two cylindrical members,  28 ,  30 , to be joined, with the left hand member  28  clearly showing an eccentrically located, male splined shaft  35  and locating dowel  37 , which are to mate with the female splined receptacle  39  and dowel bore  42 , respectively, in the right hand member  30 . Note that each of the two members has a cylindrical extension ( 44  left and  46  on the right) from the face of the member that is somewhat smaller in outer diameter than the rest of the member. The outer surface of these extensions is threaded, with the cylindrical extension  44  on the left member having a left-hand thread  48 , and the cylindrical extension  46  on the right member having a right-hand thread  51 . 
         [0033]      FIG. 3  shows the two members lined up in preparation for joining. 
         [0034]      FIGS. 4 and 5  show an internally threaded female coupling  53 .  FIG. 4  shows a side view of the coupling, with a window in the coupling revealing the threads on the left inside surface  54  being left-handed, and those on the right inside surface  55  being right-handed.  FIG. 5  is a perspective view of the coupling, showing the right hand female threads  55  on the inner surface of the right hand side. 
         [0035]    Moving to  FIG. 6 , the two members  28 ,  30  are positioned to be joined with the threaded female coupling  53  (shown semi-transparent) situated between them. The left and right cylindrical members are pushed together, engaging the female threaded coupling  53 . The coupling, in keeping with the invention, is rotated as shown by arrow A in  FIG. 7 , thereby engaging the threaded extensions  48 ,  51  and pulling the two members together without requiring relative rotation of either member. This allows the splined shaft and locating dowel  37  to travel straight into the female splined receptacle  39  and dowel bore  42  as the members are drawn together by the rotation of the coupling, until the members seat firmly against one another as seen in  FIG. 8 . 
         [0036]    Note in  FIG. 8 , which shows cylindrical members  28  and  30  firmly connected via female coupling  53 , there remains a gap  54  between the ends of the female coupling  53  and the edges  45  and  47  of the outer housings of cylindrical members  28  and  30 . As the connection between cylindrical members  28  and  30  is made up, as shown in  FIG. 7 , the rotation of female coupling  53  draws the two cylindrical members  28  and  30  together,  FIG. 9 , until the inner faces of cylindrical extensions  44  and  46  contact and bear on one another, as seen in  FIG. 10 . At this point, female coupling  53  is tightened to the desired torque, and the connection is complete, This contact between the cylindrical extensions  44  and  46  occurs before the ends of female coupling  53  contacts the housing edges  45  and  47 , leaving a gap  54 . This is necessary to assure that the threaded connections between the female coupling  53  and the cylindrical extensions  44  and  46  are fully made up and evenly loaded. 
         [0037]      FIGS. 2 through 10  show the basic principle of the current invention. However, in practice, the resulting connection between cylindrical members  28  and  30  will almost always require some mechanism to effect a pressure and fluid entry seal between the external environment and the inside of the joined cylindrical members  28  and  30 .  FIGS. 11 and 12  show one commonly employed method to effect such a seal. 
         [0038]      FIG. 11  shows the ends of the two cylindrical members  28  and  30 , to be joined, as shown in  FIG. 2 , but with added sealing surfaces  60  and  64  outboard of the cylindrical extensions  44  and  46 . Sealing surfaces  60  and  64  are shown with O-rings  62  and  66  placed in O-ring grooves (not shown) machined into the sealing surfaces of  60  and  64 . 
         [0039]      FIG. 12  shows a side view of the female coupling  53  adapted for the O-ring sealing of the connection between cylindrical members  28  and  30 , with the window in the coupling revealing the threads on the left inside sealing surface  55  being left-handed, and those on the right inside sealing surface  56  being right-handed, and the female sealing surfaces  61  and  65 , which fit snugly over the male sealing surfaces  60  and  64 , effecting a seal with O-rings  62  and  66 . 
         [0040]    The two cylindrical members  28  and  30 , show in  FIG. 11 , are joined via the internally threaded coupling  53  in the same manner as is shown in  FIGS. 3, 6, 7, 8 , and  10 . 
         [0041]      FIGS. 13 and 14  show the process of making up the connection between cylindrical members  28  and  30 , similar to what is shown in  FIGS. 9 and 10 , with cylindrical members  28  and  30  drawn together by the rotation of female coupling  53  until the faces of cylindrical extensions  44  and  46  contact and bear against one another, leaving a gap  54  between female coupling  53  and the housing edges  45  and  47  of cylindrical members  28  and  30 , respectively. 
         [0042]    Although the current invention is particularly well suited for joining cylindrical members with offset internal components, the current invention can just as easily be used to join cylindrical members with concentric components, or bores, in lieu of the more conventional internally flanged or threaded connection. Also, the current invention can be utilized to join cylindrical members of different outside diameters by using a female coupling  57  adapted to the different threaded diameters, as shown in  FIGS. 15 and 16 . 
         [0043]    It will be appreciated as well that those skilled in the art, upon reading this detailed description, may think of some variations in structure and form, such variations are within the contemplation of the invention as described and claimed in the following: