Abstract:
A pipe connecting device designed for detachable, sealing assembly of two pipe ends which device consists of an outer part and an inner part inserted axially into the outer part and cooperating therewith for internal connection to the first pipe end. The cooperating contact surfaces of both the inner part and the outer part are conical in shaped. Furthermore, means are arranged to prevent axial movement between the conical contact surfaces.

Description:
PRIOR APPLICATION 
   This application is a U.S. national phase application based on International Application No. PCT/SE01/02859, filed 20 Oct. 2001, claiming priority from Swedish Patent Application No. 0004774-6, filed 21 Dec. 2000. 
   TECHNICAL FIELD 
   The present invention relates to a sealing connecting device for joining two pipe ends. 
   BACKGROUND ART 
   Connecting devices for sealing connection between two pipe ends have previously been used which have an internal diameter fitting the outer diameter of one of the pipe ends and an external diameter fitting the inner diameter of the other pipe end. These seals must therefore be manufactured with tolerances in relation to the diameters of the pipes to be joined, which means that very many seals must be available in order to provide connections between pipe ends of varying diameters. 
   It is also known through U.S. Pat. No. 3,913,928, for instance, to use one and the same connecting device to join a pipe of a specific diameter to another pipe of a specific diameter, where this second pipe can assume one of two possible diameters. In this case the connecting device is provided with a collar that can be peeled back over the device so that it assumes a larger outer diameter. This type of connecting device must also be manufactured with tolerances in relation to the pipes and many devices are required to cover many ratios between diameters. 
   Also known through SE patent 9600828-9 (510 262) is a flexible nipple, a so-called combination nipple, by means of which a first pipe is connected to a second pipe, the first pipe assuming one of two possible diameters and the other pipe also assuming one of two possible diameters. However, this type of connecting device must also be manufactured with tolerances to enable connection to specific pipe diameters. One variant of said combination nipple is manufactured, for instance, under the designation 75-70/50-40 and another under the designation 64-58/50-40 signifying D1-D2/d1-d2 which means D1 or D2 connected to d1 or d2. 
   Difficulties are thus encountered with these known connecting devices in joining a first pipe to a second pipe, using the same connecting device, where the diameter of one of the pipes is permitted to lie within an interval rather than having a specific value. It also is difficult to obtain a tight connection to a pipe end that is not entirely circular. 
   OBJECT OF THE INVENTION 
   The object of the present invention is to solve the above problems and to provide a pipe connecting device for a sealing fit between two pipe ends, which device enables stepless adaptation of the device within an interval of pipe diameters. 
   Another object of the present invention is in a better way than previously to achieve a tight seal between two pipe ends by expanding a pipe connecting device towards the inner surface of a pipe end. 
   The object of the present invention is also to achieve a tight seal to a pipe end that is not entirely circular, i.e. may be slightly oval. 
   SUMMARY OF THE INVENTION 
   The above objects are fulfilled by means of the present invention as revealed in the characterizing parts of the claims, and said drawbacks are eliminated. 
   The invention relates to a pipe connecting device designed for detachable, sealing assembly of two pipe ends. The device consists of an inner part and an outer part co-operating with the inner part for internal connection to one of the pipe ends. The co-operating contact surfaces of the inner part and the outer part are conical in shape. Means are also arranged to prevent axial movement between the conical contact surfaces. These means preferably comprise the two conical contact surfaces being provided with a co-operating thread profile having trapezoidal shape, for instance. 
   Two pipe ends are joined by inserting one end of the inner part axially into the outer part of the connecting device. Thereafter the outer part of the connecting device is inserted into the first pipe end, whereafter the inner part is pressed, e.g. screwed into the outer part in order to expand the outer part towards the inner surface of the first pipe end. A second pipe end is then connected in a first embodiment to the other end of the inner part which is designed, e.g. with a lip ring seal in a sealing groove, to take the pipe end. 
   In a second embodiment the outer part is provided with an inner sealing sleeve rigidly attached to the outer part, against which sleeve an inner pipe end, i.e. with smaller diameter, seals when the inner part of the connecting device is pressed down into a narrowing space between the outer part and its rigidly attached sealing sleeve by means of a screwing movement, for instance. 
   Within the scope of the invention the other end of the inner part may also be provided with a corresponding outer part having mutually co-operating conically threaded contact surfaces for internal connection to a second pipe end. The inner part may also be bent in order to join pipe ends whose axes are not parallel. The means preventing axial movement between inner and outer parts may also be in the form of external clamping means or, quite simply, may consist of a glue joint. 
   The pipe connecting device in accordance with the invention is preferably used when joining waste pipes in joists or in concrete. The main area of application for pipe connecting devices in accordance with the invention is when connecting a new waste pipe in an existing waste pipe made of cast iron. These old waste pipes often vary considerably in dimension. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described in more detail with reference to the accompanying drawings. 
       FIG. 1  shows an end view of a pipe connecting device in accordance with the present invention. 
       FIG. 2  shows an enlargement of a section alone the line A—A through the pipe connecting device in  FIG. 1 , with the addition of two pipe ends. 
       FIG. 3  shows an outer part of the pipe connecting device in accordance with the invention, and a detail of the surface of the outer part. 
       FIG. 4  shows a section B—B through the part shown in  FIG. 3 . 
       FIG. 5  shows a section corresponding to  FIG. 2  in accordance with a second embodiment of the present invention. 
   

   DESCRIPTION OF THE INVENTION 
     FIG. 1  shows an end view of a pipe connecting device  1  for joining a first pipe end  2  to a second pipe end  3 . The second pipe end  3  is inserted axially into an inner part  4  of the pipe connecting device  1 . The inner part  4  is also provided with a key handle  5  intended for turning the inner part  4  in relation to an outer part  6  of the pipe connecting device. 
     FIG. 2  shows the pipe connecting device in an axial section, the second pipe end  3  being inserted in a neck portion  7  of the inner part  4  of the pipe connecting device. The neck portion is provided with a sealing groove  8  in which a lip seal  9  is situated, constituting a gas seal for slight pressure in the direction of the first pipe end. The inner part of the pipe connecting device is provided at the other end with a conical outer surface  10   a , narrowing towards the bottom, which is provided with a trapezoidal thread  11 . The surface  10   a  terminates in an annular central flange  12 , towards the middle of the inner part. 
   An outer part  14 , provided with an annular end flange  13 , is also arranged having a conical inner surface  10   b  co-operating with the conical outer surface  10   a  of the inner part. The conical inner surface  10   b  of the outer part is also provided with trapezoidal threading corresponding to the inner part. The cylindrical outer surface  15  of the outer part abuts directly, or indirectly as shown in  FIG. 2 , against the first pipe end  2 . The inner part is also provided with an internally narrowing neck portion  16  arranged so that one inner diameter of the inner part is the same as the inner diameter of the other pipe end  3 . 
   The function of this construction is that screwing the inner part  4  into the outer part  14  causes the outer part to expand steplessly radially, whereupon the connecting diameter of the outer part can be varied within an interval. This expansion also equalises any ovalness in the pipe end. 
     FIG. 3  shows the outer part  14  which, according to the present embodiment, consists of a primary part  17  and a secondary part  18  with one end concentrically connected to one end of the primary part. The figure also shows, partly enlarged, that the outer surface of the primary part  17  is provided with wedge-shaped sealing rings  19 . The inner surface of the secondary part  18  is also provided with wedge-shaped sealing rings. 
     FIG. 4  shows the primary part  17  of the outer part enlarged in an axial section which clearly shows the inner conical surface  10   b  of the outer part, provided with trapezoidal threading. Its outer surface also shows the wedge-shaped sealing rings  19 . The figure also shows the wedge-shaped sealing rings  20  on the inner surface of the secondary part  18 . The primary part  17  passes via a breaking ring  21  to the secondary part  18 . The secondary part  18  has an inner diameter that is equal, or substantially equal, to the outer diameter of the primary part  17 . The secondary part  18  also has an outer diameter that is greater than the outer diameter of the primary part  17 . The secondary part  18  is thus intended to be folded back over the primary part in order to achieve an expansion interval with larger diameter. The secondary part can easily be removed by cutting it off in order to adapt the connection to an expansion interval with smaller diameter. This design of the outer part enables stepless connection of the outer part to the other pipe end in an interval of inner diameters between a minimum corresponding to the outer diameter of the primary part of the outer part at rest, and a maximum corresponding to the secondary part of the outer part expanded. The outer part can thus be used for two diameter intervals which overlap each other, i.e. 65–75 mm and 73–83 mm. 
   To connect a first pipe end  2  to a second pipe end  3 , the inner part  4  is first screwed about half way into the outer part  14 , after which the inner part, together with the outer part, is introduced into the first pipe end  2 . Thereafter, the outer part  14  is expanded towards the inner surface of the pipe end  2  by the inner part  4  being screwed further into the outer part  14 . The second pipe end  3  is then inserted into the other end of the inner part, past the lip seal  9  and the connection is then complete. Alternatively, the second pipe end  3  is inserted into the other end of the inner part  4  before the outer part  14  is inserted and expanded. The method used is dependent on how flexible the pipes are. After assembly, it is the expanded side of the pipe connection which is the most fixed connection, whereas the pipe that is inserted past the lip seal can be displaced axially. 
     FIG. 5  shows a second embodiment of the invention in which the pipe connecting device  1  is arranged, in similar manner to that described above, so that its outer surface  15  connects with the first pipe end  2  with large diameter, and the pipe connecting device is also provided with an inner sealing sleeve  51  to connect with the second pipe end  3 . The inner sealing sleeve  51  is rigidly joined to the outer part  54  of the pipe connecting device so that a conical space  55  is formed in the outer part. As described above the outer surface of the outer part is expanded towards the inner surface of the first pipe end when the inner part  4  of the pipe connecting device is pressed, e.g. screwed, down into the outer part  54 . The inner sealing sleeve  51  is simultaneously pressed inwardly towards the second pipe end  3 . A tight joint has thus been achieved between two pipe parts  2 ,  3  of different diameters.