Abstract:
The invention provides a connector for connecting to an end of a tube, the connector comprising a hollow connector body having an opening for receiving the end of the tube, the connector further comprising gripping means for gripping the tube to hold it against retraction and sealing means for forming a seal between the tube and the connector body, wherein the connector body is formed from an opaque material but has a window therein formed from a transparent material through which an end of the tube can be seen when the tube is correctly located within the connector.

Description:
[0001]    This invention relates to a connector for pipes and tubes. 
       BACKGROUND OF THE INVENTION 
       [0002]    Connectors for tubes are known which have a hollow connector body and openings at one or both ends thereof for receiving an end of the tube(s). The connectors are typically provided with means for gripping the tube to prevent its retraction, and means for providing a seal (e.g. a fluid-tight seal such as a water-tight or gas-tight seal) between the tube and the connector body. 
         [0003]    One common arrangement for holding the tube within the connector and providing a seal comprises a collet and an array of grab rings and sealing rings such as O-rings. The grab rings, which are typically formed of a metal material, have teeth which are inclined away from the end openings and which grip the surface of the tube. If an attempt is made to pull the tube out of the connector, the angle of inclination of the teeth means that they dig deeper into the wall of the tube and so prevent the tube from being retracted through the grab ring. The collet, which serves to hold the grab ring(s) and sealing ring(s) in place, is typically provided with a plurality of resilient arms which form a snap fit in lateral openings in the wall of the connector body and therefore cannot be retracted from the connector body without first depressing the resilient arms using a suitable tool. 
         [0004]    Push fit connectors of the aforementioned type provide a generally very effective and secure means of connecting tubes together. However, they will only do so if the tubes are pushed in far enough to engage the gripping and sealing means correctly. If they are not pushed in far enough to make contact with and be gripped by the gripping means (e.g. the grab ring), then the joint formed between the connector and the tube may fail as soon as any axial tension is applied to the tube. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention set out to provide a means of overcoming the problem described above and does so by providing a connector with a transparent window in an otherwise substantially opaque connector body, through which window can be seen the end of a tube when the tube is correctly located in the connector and is in engagement with the gripping and sealing means. 
         [0006]    Accordingly in a first embodiment, the invention provides a connector for connecting to an end of a tube, the connector comprising a hollow connector body having an opening for receiving the end of the tube, the connector further comprising gripping means for gripping the tube to hold it against retraction and sealing means for forming a seal between the tube and the connector body, wherein the connector body is formed from an opaque material but has a window therein formed from a transparent material through which an end of the tube can be seen when the tube is correctly located within the connector. 
         [0007]    The term “tube” as used herein is used in a broad sense to refer to tubes, pipes and formations of a tube or pipe-like nature. 
         [0008]    In one embodiment, the term refers in a narrow sense to a tube per se. 
         [0009]    The connector body may be configured to be connected to only a single tube or it may be configured to be connected to a plurality of tubes (e.g. two or three tubes). 
         [0010]    When it is connected to only a single tube, it may be, or example, provided with means for attachment to an installation such as a bulkhead or an outlet from or inlet to a machine or reservoir. It may alternatively be used as an end cap for a tube. 
         [0011]    More typically, the connector has openings at two or more ends thereof for connecting to the ends of two or more tubes. 
         [0012]    For example, in one embodiment, the connector may be configured to connect together a pair of tubes. 
         [0013]    In another embodiment, the connector may be configured to connect together three tubes, e.g. in a Y-connector. 
         [0014]    In a preferred embodiment, the connector has openings at two ends thereof and a central passageway linking the openings, each of the two ends being provided with means for gripping a tube to hold it against retraction and means for forming a seal between a tube and the connector body. 
         [0015]    The connector body is formed from a material (e.g. a plastics material) which is substantially opaque except where the window is formed. 
         [0016]    The window may be defined by an insert formed from a transparent material (e.g. a transparent plastics material) which is held within a cavity or channel in the connector body. The insert may be formed separately and then inserted into the cavity in the connector body. Alternatively, the insert may be formed integrally with the connector body. 
         [0017]    The insert may, for example, be held within a cavity in the form of a channel extending transversely across the connector body. The channel may be cylindrical in form, and the insert may take the form of a plug (e.g. a cylindrical plug) which is shaped to fit within the cavity (e.g. channel). Where the insert (e.g. plug) is formed separately from the connector body, it is preferably a tight (more preferably sealing) fit within the cavity. Alternatively, or additionally, one or more sealing members may be provided for forming a seal between the insert (e.g. plug) and the connector body. 
         [0018]    The insert may have a passageway extending through it which is aligned with each opening for receiving a tube end. 
         [0019]    In one embodiment, the connector body is configured to receive the ends of a pair of tubes and has a central passageway extending therethrough, and the window is disposed at or near a mid point of the connector so that the ends of the two tubes can be seen when the tubes are correctly located within the connector. 
         [0020]    In this embodiment, the window may be defined by a plug of transparent material (e.g. transparent plastics material) which is held within a cavity in the connector body at or near the mid point thereof, and wherein the plug has a channel extending therethrough which forms part of the central passageway of the connector body. 
         [0021]    The channel though the plug may be configured to provide a pair of axially facing abutment surfaces which in use serve as stops for the ends of the pair of tubes. The abutment surfaces may be provided by a radially inwardly oriented rib or flange formed on the wall of the channel. 
         [0022]    The connector may be provided with one or more screw collars and a compression mechanism which is actuated by screwing the collars on to the connector body. More typically, however, the connector is a push fit connector. 
         [0023]    The means for gripping the tube may comprise one or more grab rings. 
         [0024]    The means for forming a seal between the tube and the connector body may comprise one or more sealing rings such as O-rings. 
         [0025]    A collet may be provided for holding the sealing means and the gripping means inside the connector body. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is a side view of a connecter according to a first embodiment of the invention with a pair of tubes attached thereto. The interior profile is shown by means of dashed lines. 
           [0027]      FIG. 2  is a side view of the connector body of the connector of  FIG. 1  but with the tubes and the transparent window plug omitted. 
           [0028]      FIG. 3  is a side view of the transparent plug omitted from  FIG. 2 . 
           [0029]      FIG. 4  is an exploded view of the components of the gripping and sealing assembly used in the connector of  FIGS. 1 to 3 , the arrow D indicating a direction from the connector interior to the opening at the end of the connector body. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    The invention will now be described in more detail, but not limited, by reference to the specific embodiments illustrated in the accompanying drawings  FIGS. 1 to 4 . 
         [0031]    As shown in the drawings, the connector comprises a hollow connector body  2  formed of an opaque moulded plastics material and having openings at either end thereof. The interior of the connector body comprises a pair of wider bore regions  6  at the two ends (shown by means of the dotted line in  FIG. 2 , each of which leads via a pair of step surfaces  8 ,  10  and an inclined linking surface  12  to a restricted bore region  14 . The two restricted bore regions  14  open out into a transversely extending cylindrical cavity  16  at the mid-point of the connector body. At one end of the cylindrical cavity  16  is a radially in-turned flange or lip  18 . 
         [0032]    A plug  20  of a transparent plastics material is located in the transverse cylindrical cavity  16 . The plug  20 , which is shown in cross section in  FIG. 3 , has a stepped end  22 , upon which is mounted a sealing ring  24  formed from a suitable elastomeric sealing material. At the other end of the plug  20  is a radially outwardly oriented flange  26  which is generally circular in form but wherein two chord-shaped sections have been removed on opposed sides to give two flat edges  28 . During assembly, the flat edges are aligned with the raised edges  19  on the connector body thereby ensuring that the plug  20  is in the correct orientation within the cavity. Inwardly of the flange  26 , the surface of the plug  20  has a circumferential channel  30  in which is seated a second sealing ring  32 . 
         [0033]    The stepped end  22  of the plug is of a size such that it fits through the opening defined by the in-turned flange or lip  18  and the leading edge of the stepped end is substantially flush with the outer surface of the connector body. The sealing ring  24  is held and compressed between the step  23 , the inner wall of the cylindrical cavity  16  and the in-turned flange or lip  18  so as to form a substantially fluid tight seal. The sealing ring  32  is compressed between the plug  20  and the inner wall of the cylindrical cavity  16  so that it provides a fluid tight seal at the other end of the plug  20 . 
         [0034]    The plug  20  has a transverse passageway  34  which is aligned with the longitudinal axis of the connector body and communicates with the restricted bore regions  14  of the connector body. The transverse passageway  34  has a centrally located radially inwardly oriented rib or flange  36 , the two sides  36 ′ of which act as end stops for any pipes or tubes inserted into the connector. 
         [0035]    The two wider bore regions  6  together with the restricted bore regions  14  and the transverse passageway  34  through the plug together form a central passageway extending from one end of the connector to the other. 
         [0036]    Each of the two wider bore regions  6  contains an assembly (shown in exploded view in  FIG. 4 ) for gripping and sealing against an end of a pipe or tube inserted into the connector. 
         [0037]    Each assembly comprises, in sequence in a direction D towards the opening at the end of the connector body, an inner grab ring  38 , an inner spacer ring  40 , an outer grab ring  42 , an outer spacer ring  44 , a sealing O-ring  46  and a collet  48 . 
         [0038]    The inner grab ring  38  which is seated against the inclined surface  12 , is formed from a metal material and has an array of radially inwardly oriented teeth  38   a  which are slightly inclined towards the mid-point of the connector. The inner spacer ring  40 , which is formed from a plastics material, has an inclined inner surface  40   a  which forms a seat which accommodates outer grab ring  42 . The outer spacer ring  44 , sits between the outer grab ring  42  and an O-ring sealing ring  46  formed from a suitable elastomeric sealing material. 
         [0039]    The gripping and sealing assembly is completed by the collet  48  which holds the grab rings, spacers and O-ring in place. 
         [0040]    The collet, which is substantially cylindrical in shape, is formed from plastics material and has four resilient arms  50 , each of which has an enlarged end  52  with an inclined leading surface  54  and a trailing surface  56  which is substantially perpendicular to the axis of the connector. The terms “leading” and “trailing” in the present context refer to the orientation of the surfaces as the collect is pushed into the connector body during assembly. Thus, during assembly of the connector, the enlarged ends  52  of the resilient arms  50  form a snap fit into lateral openings  60  in the wall of the connector body. Once the enlarged ends of the resilient arms have snapped into place, the trailing surfaces  56  on the enlarged ends prevent retraction of the collect from the connector body. 
         [0041]    The lateral openings  60  in the wall of the connector body  2  are concealed by means of C-shaped spring clips  62  which are held in correspondingly shaped near circumferential recesses  64  running around the exterior of the connector body. 
         [0042]    Prior to use, the two ends of the connector are closed by means of end caps (not shown) which prevent dirt and other contaminants entering the interior of the connector. 
         [0043]    In use, the end caps are removed and tubes T are inserted into the two ends of the connector. The tubes T form a tight friction fit within the collets  50 . The tubes T are inserted so that the ends of the tubes pass through the grab ring and sealing ring assemblies and into the transverse passageway  34  through the plug where they abut against the two sides  36 ′ of the radially inwardly oriented rib or flange  36 . The plug  20 , which is formed of a transparent plastics material, acts as a window through which it can be seen whether or not the ends of the tube have been pushed into the connector far enough to engage the gripping and sealing assembly. 
         [0044]    Thus, the connector of the invention provides a solution to the problem of establishing whether or not tubes have been pushed sufficiently far enough into a connector to form a secure sealed connection. 
         [0045]    The invention has been illustrated by reference to a connector which can be connected at both ends to a tube. However, it will be appreciated that the connector may be configured to enable connection to only one tube or to more than two tubes. For example, the connector could be a y-shaped three way connector. 
       Equivalents 
       [0046]    It will readily be apparent that numerous modifications and alterations may be made to the specific embodiments of the invention described above without departing from the principles underlying the invention. All such modifications and alterations are intended to be embraced by this application.