Abstract:
A tube coupling to receive and hold a tube includes a coupling body ( 10 ) having a throughway to receive a portion of a tube. A collet ( 17 ) in the coupling body has legs ( 21 ) with outer surfaces that engage with a tapered surface ( 24 ) in the coupling body which urges the legs inwardly to resist withdrawal of the tube. A biasing member ( 26 ) provides a biasing force without the tube inserted to urge the legs axially onto the tapered surface. The collet ( 17 ) can grip a large variety of pipe diameters. The coupling may be supplied with a number of inserts ( 30 A-D) for sealing with the inner diameter of a pipe, the inserts having different diameters. A tool ( 50 ) for preparing the end of a pipe to receive the coupling is also contemplated.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to United Kingdom Application No. 1205575.2, filed Mar. 29, 2012, which is incorporated herein by specific reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. The Field of the Invention 
         [0003]    This invention relates to tube couplings which may be single or multiple tube couplings providing in-line, elbow or T-couplings or tube closures. 
         [0004]    2. The Relevant Technology 
         [0005]    More specifically, the present invention relates to a tube coupling to receive and hold a tube, the coupling comprising a coupling body having a throughway open at one end to receive a portion of the tube, a collet in the coupling body to allow insertion of the tube into the collet and having a plurality of legs with outer surfaces that engage with a tapered surface in the coupling body which urges the legs inwardly to resist withdrawal of the tube. Such a coupling will subsequently be referred to as “of the kind described”. 
       SUMMARY OF THE INVENTION 
       [0006]    A coupling of the kind described is our “Speedfit” connector as disclosed in GB 1 520 742. This coupling has met with significant success over many years. The present invention is designed to extend the use of such a connector. 
         [0007]    The connector works on the principle that, as the tube is inserted, the legs of the collet expand radially to allow entry of the tube and, in doing so, grip the tube sufficiently for the collet to be pulled into the tapered surface if the tube is partially withdrawn. As the force increases to remove the tube, the interference between the taper and the collet increases, thereby increasing the grip on the tube. 
         [0008]    While this works extremely well, the design is limited to a connection for tubing with a small tolerance. As the diameter of the tube decreases, so does the force with which the collet can grip the tube. If the initial grip is too low, the gripping force is too small to overcome the removal force on the tube. 
         [0009]    It is common practice for pipes and connectors to be sold by the same company. Each system has its own size to ensure that system installation remains consistent and to the specification of each company. However, this makes retro fitting difficult as the retro fitter will need to source components from a number of manufacturers, some of whom may no longer be in existence. 
         [0010]    According to a first aspect of the present invention, a coupling of the kind described is characterised by a biasing member which provides a biasing force without the tube inserted to urge the legs axially onto the tapered surface. 
         [0011]    With such an arrangement, the connector can grip on a much larger variety of pipe outer diameters. The biasing member has the effect of urging the collet legs along the tapered surface to a position with a diameter where the taper is narrower and hence the initial position of the collet legs defines a narrower bore. If a larger diameter tube is inserted, this will simply push the collet to a wider portion of the taper against the action of the biasing member and the collet will function as described above in relation to the prior art. However, when a smaller diameter tube is inserted, the biasing means will act to maintain the collet at a smaller diameter portion of the taper thereby ensuring that the grip on the smaller diameter portion is not compromised. 
         [0012]    In effect, the action of the biasing member is to maintain the collet legs at the part of the taper appropriate for the diameter of the tube to be inserted. 
         [0013]    The coupling body may be provided with a seal arranged, in use, to seal on the outer diameter of the tube. Under such circumstances, this seal must be able to seal the different diameter tubes that can be gripped by the collet. The seal could be an O-ring made of a thicker and more resilient material than is conventional, or the coupling body could be designed to receive O-rings of different diameters. Alternatively, the seal may have a radially projecting lip that is deflected upon insertion of the tube by an amount proportional to the outer diameter of the tube. 
         [0014]    Alternatively, the coupling could be designed as an inner diameter coupling. In this case, the coupling preferably comprises a tubular insert receivable in the end of the tube, the tubular insert having a first portion insertable into the tube and a second portion receivable in the coupling body, the first portion having a seal to seal, in use, with the inner diameter of the tube, and the second portion having a seal to seal with the coupling body. A variety of such inserts may be made available, each of which has the same diameter of the second portion such that it can seal with a standard seat in the coupling body, while the outer diameter of the first portion may vary between such inserts. Thus, for the larger diameter tube, a first insert is used with a larger diameter first portion to provide an adequate seal on the inner diameter of the tube while the second portion fits in the standard seat in the coupling body, the biasing member described above and provides adequate gripping on the larger diameter tube. For a smaller diameter tube, a second insert is used with a smaller outer diameter for the first portion to seal against the inner diameter of the tube. Again, the second portion seals with the standard seat in the coupling body and the biasing member ensures that the collet legs grip the smaller diameter tube as mentioned above. 
         [0015]    Such a design of inner diameter connector is widely used with “composite” pipe in larger buildings such as office blocks. The composite pipe is multi-layer tubing with plastic (typically PEX) on the inside and outside with a layer of aluminium in the middle. To stop the aluminium from corroding, the fitting needs to seal on the inner diameter of the pipe to keep the exposed aluminium layer at the end of the pipe dry. 
         [0016]    This forms a second aspect of the present invention which is a kit comprising a coupling according to the first aspect of the present invention and at least two tubular inserts, each insert being receivable in the end of the tube, the tubular insert having a first portion insertable into the tube and a second portion receivable in the coupling body, the first portion having a seal to seal, in use, with the inner diameter of the tube, and the second portion having a seal to seal with the coupling body, wherein the first portions of the two inserts have different diameters. 
         [0017]    This kit allows a user to be in a position to make fittings to pipes of a variety of diameter tubes without needing to carry a wide range of fittings. This is highly desirable when, as often happens, a user arrives at an installation site and only knows what type of tubes are present after they have exposed them. 
         [0018]    Preferably, the kit contains more than two tubular inserts with first portions of different diameters to allow connection to a greater range of tubes. Also, preferably, the kit contains a double-ended coupling body and at least two inserts of each diameter of first portion to enable a double-ended connection to be made to a single tube. 
         [0019]    Preferably, the kit also comprises at least one of a tool to restore the circular diameter of the tube, a tool to create a bevelled edge on the inner wall of tube and a tool to deburr the outer edge of the tube. A single tool may provide more than one of these functions. 
         [0020]    Thus, an operator with this kit can arrive at a site without prior knowledge of the existing tubes and couplings. Having cut the tube he/she can reshape the cut end, create a bevelled edge and and/or deburr the pipe to prepare it for the new coupling. Then, despite only carrying a relatively small number of components he/she can make the new coupling. 
         [0021]    The connector can incorporate a coupling according to the invention at one end and a standard connector on the other end. This can allow conversion from an inner diameter to an outer diameter system. 
         [0022]    The biasing member may be positioned anywhere in which it is able to provide the necessary biasing force. For example, it may be outside the coupling body such that it acts between the end of the coupling body and a shoulder on the collet. However, preferably the biasing member is within the coupling body as there is a greater axial distance available here to accommodate the member. There are a number of ways in which the member can be configured. It may, for example, be a sleeve of elastomeric material. Alternatively, if there is a resilient O-ring within the coupling body, then a rigid sleeve could be provided between the seal and the end of the collet which compresses the seal to provide a biasing force which is transmitted via the sleeve to the collet legs. 
         [0023]    However, preferably, the biasing member is spring (e.g. a helically coiled spring, an undulating ring or a ring of opposed crosses) supported at one end within the coupling body and at the opposite end on the ends of the collet legs. 
         [0024]    The coupling body is preferably provided with a locking cover which is received on the outside of the coupling body and is movable between a first position in which, with the tube inserted, axial movement of the collet is prevented and a second position in which, with the tube inserted, axial movement of the collet is permitted. This locking sleeve prevents accidental movement of the collet to a position in which the tube is dislodged. 
         [0025]    The coupling body is preferably provided with a window, allow for visual inspection of the tube within the coupling. 
         [0026]    Preferably, the locking sleeve is configured to reveal the window in the first position and to cover the window in the second position. This allows the user to determine that the tube has been fully inserted into the correct position and also provides a visual indication of whether or not the locking sleeve is locked. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    An example of a coupling in according with the present invention will now be described with reference to the accompanying drawings, in which: 
           [0028]      FIG. 1A  is a partial axial section of a first example of a connector prior to use; 
           [0029]      FIG. 1B  is a view similar to  FIG. 1A , with a tube partially inserted; 
           [0030]      FIG. 1C  is a view similar to  FIG. 1B  with the tube fully inserted; 
           [0031]      FIG. 1D  is similar to  FIG. 1C  showing a smaller diameter tube fully inserted; 
           [0032]      FIGS. 2A ,  2 B and  2 C are perspective views of a kit according to the second aspect of the present invention; and 
           [0033]      FIG. 3  is a partial axial section similar to  FIG. 1  showing a second example of a connector. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0034]    In all Figures, the connectors illustrated are in-line connections. For simplicity, only the left-hand side of the connector is shown in cross-section. The right-hand side of the connector may have the same configuration or may be provided with a different connection mechanism as necessary. The same connector design may equally be applied to elbow or T-couplings or tube closures where again one or more of the connections is as described and others may be of different designs as necessary. 
         [0035]    The connector comprises a coupling body  10  having a through way  11  open at one end  12  to receive internally an end portion of a tube T with externally a locking cap  13  which has a central opening  14  in line with the throughway  11 . 
         [0036]    A collet  17  is received an in an open end  18  of the coupling body  10 . The collet comprises an annular portion  19  extending through the opening  18  and having an outwardly projecting annular flange  20 . The portion of the collet  17  extending into the throughway  11  in the coupling body  10  has axially extending resilient legs  21  which terminate in heads  22  with internal barbs or teeth  23  on the inner side thereof to grip the tube extending through the collet. Such collets are well known in the art. 
         [0037]    A tapered cam surface  24  is formed within the coupling body  10  and tapers inwardly towards the open end  12 . The heads  22  of the collet  17  engage with the tapered cam surface  24  such that they are compressed radially inwardly as the collet is drawn axially outwardly, thereby causing the barbs  23  to grip and engage the tube T extending through the collet  17 . The greater the force trying to pull the tube T out of the connector, the more the collet  17  is pulled to the left in the Figures and the greater the degree of compression provided to the heads  23  by the tapered cam surface  24 . The throughway  11  is provided with a shoulder  25  facing the open end  12  of the coupling body  10 . A helical spring  26  is provided within the coupling body  10  surrounding the throughway  11  and resting on the shoulder  25  at one end and the heads  22  of the collet  17  at the opposite end. The spring  26  is in compression such that it urges the collet towards the open end  12  (i.e., to the left in the Figures). This has the effect of forcing the heads  22  to a narrower part of the tapered cam surface  24 . 
         [0038]      FIG. 1B  shows the insertion of the tube T for an internal diameter (ID) connection. In this case, prior to being inserted into the coupling body  10 , an insert  30  is fitted into the end of the tube T. The insert  30  has a throughway  31  which, upon insertion, is aligned with the throughway  11  in the coupling body. The insert  30  has a first portion  32  of narrower diameter which fits inside a tube T and is provided with an O-ring  33  to seal against the inner wall of the tube T. The second portion  34  of the insert  30  remains outside the tube. This second portion is provided with an annular flange  35  providing a shoulder which abuts against the end of the tube. Towards the end furthest from the end of the tube T, the second portion  34  is provided with an O-ring  36  which seals against the coupling body  10  as described below. 
         [0039]    The tube T shown in  FIG. 1B  is the largest tube that the connector can accommodate as can be seen by the close fit between the tube T and the opening  14  on the locking cap  13 . Because the tube T has a relative large diameter, upon insertion, it engages with the inner surface of the collet  17  and the barbs  23  and pushes the heads  22  of the collet to a position in which they are at or close to the widest part of the tapered surface  24 . At this position, the collet and tapered surface are configured to provide the optimum force against withdrawal of a tube of larger diameter. 
         [0040]    When the tube T reaches the full inserted position as shown in  FIG. 1C , the seal  36  seals against an annular wall in the coupling body  10 . As will be appreciated from  FIG. 1C , seals  33  and  36  prevent the fluid in the throughway  11  from contacting the end of the tube T. 
         [0041]      FIG. 1D  shows the same connector being used for a smaller diameter tube T′. In this case, a smaller diameter insert  30 ′ is used. This is the same as the insert  30  as previously described, except that the outer diameter of the first portion  32  and consequently the O-ring seal  33  are smaller so as to fit within and seal against the inner diameter of the smaller diameter tube T′. The second portion  34  is identical to the second portion described above and seals in the same manner. 
         [0042]    Once the tube is fully in place, the locking sleeve  13  is rotated from the unlocked position shown in  FIGS. 1A and 1B  to the locked position shown in  FIGS. 1C and 1D  in which it has at least one port which is now in a position to obstruct the collet  17  as is known in the art. As best shown in the right-hand side of the Figures, the locking sleeve  13  has a scalloped lower edge  40  such that, in the unlocked position, a window  41  in the coupling body is exposed allowing a user to see whether or not the tube has been fully seated. In the locked position, the window  41  is covered as shown in  FIGS. 1C and 1D  providing a visual indication to the user that the coupling is locked. 
         [0043]    The above described connector may be supplied as a part of a kit as will now be described with reference to  FIGS. 2A-2C  which, together, disclose the elements of the kit. 
         [0044]    The connector shown in  FIG. 2A  is the connector described above. Also included as part of the kit are a number of inserts  30 A- 30 D which correspond to the inserts  30  and  30 ′ described above. The inserts come in pairs as identified by the matching letters, and each pair is identical except that the outer of each first portion  32 A- 32 D is different (increasing from  30 A to  30 D). In all cases, the second portion  34  is as previously described and fits within the connector shown in  FIG. 2A . 
         [0045]    As shown in  FIG. 2C , the kit is also supplied with a tool  50 . 
         [0046]    The tool  50  is provided with four projecting tubular elements  51 A- 51 B arranged in a cruciform. Each of the elements is labelled with a letter A-D which corresponds to the corresponding letter on the inserts. The outermost end of each element has a bevelled outer edge  52  which provides a lead-in surface. At the opposite end, each element has a pair of cutters  53 . There may be more or less than four sets of inserts  30  in which case, the number of tubular elements may be changed accordingly. 
         [0047]    When retro-fitting a connector, the user will first cut the existing tube and this will generally cause the end of the cut tube to be squashed to some extent. The user can determine visually the rough size of the inner diameter of the cut tube and can then insert the appropriate tubular element  51 A- 51 B. The bevelled edge  52  will facilitate the insertion of the tubular element into the cut end of the tube, and the continued insertion will restore the circularity of the tube in the vicinity of the cut end. The tube is pushed fully onto the tubular element such that it engages cutters  53 . Rotation of the tube will create a chamfer on the inner diameter of the tube. If the user has selected an extension which is too big for the inner diameter of the tube, it will not fit, while an extension which is too small will feel loose and will encourage them to try a larger diameter extension to see if this will fit. 
         [0048]    The tool  50  is also provided with an upwardly facing surface with reference to  FIG. 2C  with an inner cylindrical extension  54  again having a bevelled outer edge  55 . This bevelled edge  55  provides a lead in into the tube. The inner cylindrical extension  54  is surrounded by a number of cutters  56 , two of which are shown in  FIG. 2C . These are supported by an outer cylinder  57 . These cutters  56  are positioned to engage with the outer edge of the cut tube once it has been restored to its circular shape, such that rotation of the tool about the axis of the cylindrical extension  54  on which it is located causes the cutters  55  to scrape the outer edge of the tube thereby deburring the tube. The bevelled edge  55  and cutters  56  may be designed such that they fit all diameters of the tube with which the kit is designed to be used. Alternatively, the bevelled edge  55  and cutters  56  on one side of the tool may be sized to deal with some of the sizes of the inserts, while the opposite side of the tool may have a similar arrangement sized to deal with the remaining sizes of insert. 
         [0049]    Armed with the kit shown in  FIGS. 2A-2C , the user can arrive at a site without any knowledge of the diameters of the tubes that they will be dealing with. Having cut out an existing connector, the tool  50  can be used to restore the circular shape of the tube ends and also to provide the user with an idea of which size of inserts they need to use to re-make the connection. The bevelled edge  54  and cutters  55  enable them to quickly clean the end of the pipe and prepare it to receive the inserts whereupon they can insert the appropriate insert into the cut ends of the pipe and attach the connector as described above. 
         [0050]    A second example of a connector is shown in  FIG. 3 . 
         [0051]    This has a number of components that are the same as, or similar to those in the first example, and the same reference numerals have been used to designate the same components where appropriate. 
         [0052]    The example of  FIG. 1  was for an ID connection, whereas the example of  FIG. 3  is for an outer diameter (OD) connection. 
         [0053]    As shown in  FIG. 3 , a cartridge ring  60  forms part of the coupling body  10  and is held in place by anchoring teeth  61 . It could equally be welded in place. 
         [0054]    The main difference in the second example is that there is now an annular seal  62  within the coupling body. This is positioned distally of the helical spring  26  to surround the throughway  11  and sits on a shoulder  63  which faces the open end  12 . The end of the annular seal  62  facing the open end forms the shoulder  25 ′ on which the spring  26  sits. 
         [0055]    The annular seal  62  has an annular lip  64  which projects radially inwardly and is inclined away from the open end  12 . The lip  64  tapers inwardly towards its radially innermost edge. 
         [0056]    Upon insertion of a tube, the operation of the collet  17  and spring  26  is as previously described. 
         [0057]    When a tube with a relatively large outer diameter is inserted, the lip  64  is deformed radially outwardly to a relatively large extent. On the other hand, a relatively small tube would provide a relatively small deflection of the lip  64 . In either case, the direction in which the lip projects and the tapering nature of the lip ensure that an adequate seal is maintained for a range of tube diameters.