Abstract:
A fitting for a pipe, has a base body and a connecting body, each having a passage for a fluid. Both bodies include contact surfaces that can be slid into each other, including at least one pair of opposing recesses forming a receiving chamber. The fitting has a flexible, substantially incompressible locking element that can be inserted into the receiving chamber for fixing the two bodies together. At least one of the two bodies includes an access chamber extending between an outer surface of the associated body and the receiving chamber. The access chamber connects to and is an extension of the receiving chamber. The locking element includes a stop protrusion at one of its opposite ends for stopping the locking element externally at least one of the two bodies in order to prevent the locking element from unintentionally slipping out of the receiving chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the National Stage of International Application No. PCT/EP2009/056958, filed on Jun. 5, 2009, which claims the priority of German Patent Application No. 10 2008 027 382.1, filed on Jun. 9, 2008. The contents of both applications are hereby incorporated by reference in their entirety. 
     A press fitting for a pipe, particularly a plastic pipe or a plastic and metal composite pipe. 
     FIELD OF DISCLOSURE 
     The invention relates to a fitting for a pipe, particularly a plastic pipe or a plastic-metal composite pipe. 
     BACKGROUND 
     Fittings for pipes are known in a wide variety of embodiments. Said fittings are typically constructed as a whole piece, for example, as pipe connectors, tees, elbows, or bulkhead fittings. Each pipe cross section requires the production of special fittings, which drives up the number of variants needed. 
     Modular fitting systems have previously been proposed, in which connecting bodies of various dimensions can be attached to a base part, such as a tee or an elbow. Examples of such modular or adaptive fittings are found in DE 42 04 430 A1 and DE 10 2006 026 263 B3. 
     SUMMARY 
     The object of the invention is to provide a modular fitting for a pipe, particularly a plastic pipe or a plastic-metal composite pipe having a simplified, releasable, or repeatedly releasable joining technique. 
     The object is achieved according to the invention by a fitting for a pipe, particularly a plastic pipe or a plastic-metal composite pipe, wherein the fitting has
         a base body having a passage for a fluid,   a connecting body releaseably connectable to the base body, also comprising a passage for a fluid, to which a pipe can be connected,   wherein both bodies comprise contact surfaces that can be slid into each other and comprising at least one pair of opposite recesses forming a receiving chamber, and   a substantially incompressible and flexible locking element that can be inserted into the receiving chamber for fixing the two bodies to each other,   wherein at least one of the two bodies comprises an access chamber extending between an outer surface of said body and the receiving chamber,   wherein the access chamber substantially connects to the receiving chamber as an extension thereof, and   wherein the locking element comprises a stop protrusion at one of the opposite ends thereof for stopping the locking element externally at least one of the two bodies, for preventing the locking element from unintentionally slipping out of the receiving chamber.       

     The fitting according to the invention comprises a base body and a connecting body releaseably connectable to the base body. Both bodies comprise passages for a fluid connecting to each other in the connected state of the two bodies. The concept of assembling a fitting from a base body and a connecting body has the advantage that a plurality of different connecting bodies can be attached to one and the same base body. Said connecting bodies can differ with regard to the geometry of the pipe to be connected (pipe dimensions), but also with regard to the joining technique of the pipes to the connecting bodies. It is thus possible, for example, to connect press fit, slip fit, and threaded sleeve connector bodies to one and the same base body. 
     A modular fitting has further advantages in the production method. The base body of the fitting can be produced only by die forging or casting, with high tooling costs, because it is generally not rotationally symmetrical. The connecting body and insert parts, in contrast, are generally rotationally symmetrical to the base body. A fitting is thus divided into a part that can be produced less simply (base body) and a part that can be produced more simply (connecting body). The more simple production of the connecting body has advantages for the overall production costs of the fitting. Using only a few die-forged or cast base bodies (such as elbows or tees), a complete fitting system can be established over a very wide range of nominal sizes (such as 25 to 110 mm). A modular fitting system further has the advantage that pressing the pipe to the fitting is not necessarily required at the construction site or at the site of the installation of the fitting, but can be done elsewhere, in that the connecting body is connected to the pipe, in order to connect the connecting body to the base body later. 
     The two bodies of the fitting according to the invention are slid into each other for connecting to each other. The two bodies thus have contact surfaces that can be telescoped and that face each other in the telescoped state. The contact surfaces, comprising in the simplest case a cylindrical external surface on one body (such as the connecting body) and a cylindrical internal surface on the other body (such as the base body), have at least one pair of recesses (such as grooves) facing each other in the telescoped state, that together define a receiving chamber. A strand-shaped locking element is inserted into said receiving chamber, fixing and thus locking the two bodies to each other like a feather key. 
     The particular feature of the fitting according to the invention is that a flexible, substantially incompressible locking element can be inserted into the receiving chamber from the outside. For this purpose, one of the two bodies has an access chamber (in the shape of a borehole in the simplest case) connecting the exterior of the body and the receiving chamber to each other and extending between the two. The access chamber thereby opens substantially continuously, that is, substantially without protrusions, into the receiving chamber. If the receiving chamber is (partially) annular in design, which is the case for cylindrical contact surfaces, the access chamber opens tangentially into the receiving chamber. An incompressible, flexible, substantially strand-shaped locking element in the form of, for example, a string, chain, cord, wire, or the like can now be inserted through the receiving chamber from the outside. 
     The recesses forming the receiving chamber between the two bodies, when said bodies are inserted into each other, extend expediently over a circumferential angle range of 180°, for example. The greater the circumferential angle over which the receiving chamber extends, the better tipping motions acting between the two bodies can be absorbed. In this respect, it is advantageous if the opposite recesses forming the receiving chamber extend along a circumferential angle of greater than 180°, particularly of up to 300°. If embodied as a helix, the recesses can even extend beyond 360°. 
     Furthermore, according to the invention, the locking element is stopped and fixed at the base body and/or connecting body, thus preventing unintentionally slipping out of the receiving chamber. For this purpose, the locking element comprises a stop protrusion at one of the opposite ends thereof, said protrusion engaging with a stop surface implemented on the base and/or connecting body, for example by hooking or otherwise engaging both elements, thus preventing the locking element from slipping out of the receiving chamber, and preventing the locking element from moving relative to the receiving chamber. 
     In an advantageous further development of the invention, the locking protrusion is also used for handling the locking element when inserting into the receiving chamber. This can be implemented either directly by manually exerting pressure by hand on the locking protrusion, for example; alternatively, using a tool is also possible. It is further advantageous if the locking protrusion also comprises a handling element, particularly a borehole, a recess, or a raised area for engaging a pulling tool by means of which the locking element can be pulled back out of the receiving chamber if necessary. 
     In order to be able to better protect the telescoping contact surfaces of the base body and connecting body against entry or loss of fluid, it is advantageous if at least one of the two bodies has a sealing element disposed ahead of the recess forming the receiving chamber, as seen from the passage of the particular body. Not only is the exit of fluid from the area between the telescoped contact surfaces prevented, but fluid is also stopped from entering the area of the receiving chamber. 
     As indicated above, the locking element that can be inserted in the receiving chamber is flexible and substantially incompressible. A plastic string, metal wire, flexible shaft or wire strand, or a chain are particularly suited as the locking element. The locking element must be able to be pushed completely through the access chamber and into the receiving chamber. It is thereby guided in both chambers by contact with the boundary surfaces thereof. Thus, when it is at least in the access chamber, the locking element can no longer yield laterally, but can be inserted further into the fitting, until it extends over the cross section of the receiving chamber, and thus can assume its locking function. 
     In an advantageous further development of the invention, one of the two bodies further has an additional access chamber. Both access chambers are thereby located at opposite ends of the receiving chamber, where they each open into the same preferably substantially continuously and smoothly. Using such a design, it is possible to pull the locking element back out, which is preferably flush with or recessed relative to the outer contour of the fitting in the inserted state. For this purpose, the locking element is inserted further into the receiving chamber, for example, until it is at least partially pushed out of the fitting again through the further access chamber adjacent to the receiving chamber. The end that is pushed out can then be captured using a gripping tool, such as a pliers or the like, and the locking element can thus can be pulled completely out of the fitting. Thus the locking between the base body and the connecting body is released, and the two can be separated from each other. 
     In an advantageous further development of the invention, both access chambers terminate adjacent to each other at the outer surface of the base body and/or connecting body. The outer surface of the respective body or bodies thereby comprises protrusions terminating in surfaces extending at angles to each other. Both of said surfaces are immediately adjacent to each other. When the locking element is completely inserted in the access chambers and the receiving chamber, the locking protrusion is located between the two surfaces, whereby for locking, the locking protrusion interacts with the edge of the opening of the one of the two access chambers in which the end of the locking element facing away from the locking protrusion is present. 
     In order to insert the locking element through the access chamber into the receiving chamber of a fitting, according to the previously mentioned example embodiments of the invention, a tool having a tool body is proposed, said tool body comprising a receptacle for receiving the end of the flexible, substantially incompressible locking element. Using said tool body, the locking element can be inserted through the access chamber into the receiving chamber. 
     In order to be able to remove the locking element out of the receiving chamber again in the case of an embodiment of the fitting having two access chambers, the tool has a flexible extension at its tool body for inserting in one of the two access chambers. Using said extension, the flexible locking element can be pushed forward until it partially protrudes out of the access chamber at the rear in the insertion direction past the outer surface of the fitting, so that said protruding area can then be captured by a gripper tool in order to remove the locking element completely out of the receiving chamber. 
     The flexible extension is expediently formed of the same material as that of the locking element and its cross section extends over the cross section of the access and receiving chambers or is smaller than this. As indicated above, the locking element is, for example, a plastic string. Therefore, the flexible extension is also formed from a piece of the same string. 
     The invention finally further relates to the use of a tool having a receptacle for receiving an end of the flexible, substantially incompressible locking element of a fitting of the type described above, in that as the end of the locking element is received by the receptacle, it is pushed through an access chamber into the receiving chamber. A further use of said tool having a flexible, substantially incompressible mandrel for inserting into one of the access chambers of a fitting according to one of the previously described embodiment examples relates to moving the locking element partially out of the receiving chamber and into, as well as out of, the other access chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described in more detail below, using an embodiment example and referencing the figures. They show: 
         FIG. 1  perspective and explosion view of the individual components of a fitting having a base body and connecting body, and a locking element for locking both bodies in the pushed together state, 
         FIG. 2  a cross section through the two bodies of the fitting in the pushed together state, but without the locking element inserted, 
         FIG. 3  a longitudinal section through the two bodies of the fitting in the assembled state, and having the locking element inserted, 
         FIG. 4  a cross-sectional view as in  FIG. 2 , but showing a tool by means of which the flexible locking element is inserted into the fitting for locking the base and connecting bodies. 
         FIG. 5  a cross-sectional view as in the  FIGS. 2 and 4 , showing the use of the tool for removing the inserted locking element out in order to release the lock on the two bodies, 
         FIG. 6  a section similar to that according to  FIG. 2 , through an alternatively implemented fitting, in which the receiving chamber extends through 270°, so that the two access chambers extending tangentially to each other terminate at the outer surface of the fitting directly adjacent to each other, 
         FIG. 7  an embodiment example of a locking element implemented as a plastic string or bar, having a stop protrusion at one end and tapering conically at the other end, wherein the segment of the locking element adjacent to the conically tapering point is pre-bent, 
         FIG. 8  the situation during insertion of the locking element into the receiving chamber of the fitting, 
         FIG. 9  the situation as the locking element is inserted so far that its locking protrusion is located near the outer surface of the fitting, and 
         FIG. 10  the situation when the locking element is fully inserted in the fitting and its stop protrusion is stopped at the fitting. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  partially shows the individual components of a fitting for pipes  11 , particularly plastic pipe or plastic-metal composite pipe, comprising a base body  12  having a fluid pass-through  14  and a connecting body  16  having a fluid pass-through  17 . The pipe  11  can be connected to the connecting body  16  (see  FIG. 3 ), for which purpose the connecting body  16  in this embodiment example comprises a support sleeve  18  and a press-fit sleeve (not shown), by means of which the pipe is pressed radially against the support sleeve ( 18 ) and press-fit. The connecting body  16  comprises a substantially cylindrical fitting body  20  that can comprise a sealing ring in the region of the support sleeve  18 . Said sealing ring seals the pipe against the support sleeve  18  in a fluid-tight manner. The connecting body  16  further comprises an insertion sleeve  22  protruding out of the fitting body  20  thereof and that can be inserted in an insertion chamber, namely the passage  14  of the base body  12 . The base body  12  has a wall  24  that is cylindrical in said embodiment example. This base body  12  can be implemented as a pipe connector for receiving two connecting bodies  16  at opposite ends as an elbow, as a wall fitting, or as a tee. The advantage of the modular fitting  10  is that the base body  12  can be used for connecting pipes having diameters of different sizes, in that one of a plurality of different connecting bodies  16  is selected for use with support sleeves  18  having different diameters. Such modular fitting concepts are known, for example, from the publications listed above. 
     As seen in  FIGS. 1 through 3 , the base body  12  and the connecting body  16  comprise telescoping contact surfaces  26 ,  28  implemented cylindrically in said embodiment example. The contact surface  26  of the base body  12  is formed by a part of the inner side of the wall  24 , whereas the contact surface  28  of the connecting body  16  is formed by a part of the cylindrical outer surface of the insertion sleeve  22 . Said two contact surfaces have circumferential grooves or similar circumferential recesses  30 ,  32  that are located opposite each other in the inserted state (see, for example,  FIGS. 2 and 3 ), that is, in a common radial plane. Said two recesses  30 ,  32  together form a substantially cylindrical receiving chamber  34 , extending along the circumference (inner circumference of the base body  12  or outer circumference of the insertion sleeve  22  of the connecting body  16 ). Two access chambers  36 ,  38  implemented in the form of boreholes (see particularly  FIG. 2 ) are also located in the base body  12 , by means of which access to the receiving chamber  34  is provided through the wall  24  from the outer surface  40  of the wall  24 . The two access chambers  36 ,  38  open substantially tangentially into the recess  30  on the inner contact surface  26  of the base body  12 . The receiving chamber  34  extends over substantially 180° in this embodiment example. By implementing the access chambers  36 ,  38  at an acute angle to each other, it is also possible that the receiving chamber  34  extending between the two access chambers  36 ,  38  runs over greater than 180°. To the extent that both recesses  30 ,  32  extend in a helical shape, the receiving chamber  34  can also extend over 360° and more. 
     As can be seen from  FIGS. 1 and 3 , an annular sealing element  42  is located around the insertion sleeve  22  of the connecting body  16  and seals the opposing contact surfaces  26 ,  28  against each other and is disposed between the passage  14  or  17  and the receiving chamber  34 . The sealing element  42  can alternatively also be located at the inner surface  26  of the base body  12 , in order to seal the contact surfaces  26 ,  28  against each other. 
     In order to mechanically lock the two bodies  12 ,  16  inserted into each other, a flexible, substantially incompressible strand-shaped locking element  44  is implemented in this embodiment example in the form of a plastic string. Said plastic string  44  is inserted from the outside into one of the two access chambers  36 ,  38  and is slid into the same, wherein it enters the receiving chamber  34  through the respective adjacent access chamber  36 ,  38 . When disposed in the receiving chamber  34 , the locking element  44  locks the two bodies  12 ,  16  in the manner of a feather key. Said locking can be eliminated by removing the locking string  44 . 
     The locking string  44  can be fed into place expediently using a (sliding) tool  46 , as is shown in  FIGS. 4 and 5 . The tool  46  comprises a tool body  48  that can be held in the hand and is preferably ergonomically formed, and having two opposite ends  50 ,  52 . The tool body  48  comprises a (centering) receptacle  54  at one end (for example, end  50 ) in which the one end of the locking string  44  is inserted when said end is slid into the access chamber  36  and through the same into the receiving chamber  34 . This situation is shown in  FIG. 4 . The tool  46  can be further used for partially moving back the locking string  44  that is completely slid into the fitting  10 , as is shown in  FIG. 5 . For this purpose, the tool body  48  comprises a flexible mandrel  56  on the other end  52  thereof, expediently made of the same material and having the same geometry as the locking string  44 . The tool  46  is made, for example, of plastic. 
     The mechanical locking of the two bodies  12 ,  16  of the fitting  10  is performed according to the invention by the flexible, substantially incompressible, strand-shaped locking element  44  when said element is located in the receiving chamber  34  formed in both bodies. It is thereby sufficient if the locking element  44  is located exclusively in said receiving chamber  34 . Extension of the locking element  44  into one or both of the access chambers  36 ,  38  is not necessary in order to implement the locking function. 
     The invention is described above using a fitting  10 , wherein the base body  12  and the connecting body  16  are locked to each other by means of a (single) locking element  44 . Depending on the retaining forces required, it may be necessary to provide a plurality of flexible, substantially incompressible and strand-shaped locking elements  44 , wherein a plurality of receiving chambers  34  are then also present. The a plurality of receiving chambers  34  can extend at different circumferential angle ranges, so that locking by a plurality of locking elements  44  is provided across the entire circumference. 
     A further embodiment example of a fitting  10 ′ shown in the  FIGS. 6 through 10 , differs from the fitting  10  of  FIGS. 1 through 5  in that the receiving chamber  34  extends over substantially 270°. In this respect, it is pointed out that the same references are used in  FIGS. 6 through 10  for such elements of the fitting  10 ′ that are identical in design and function to the elements of the fitting  10 . 
     The base body  12  of the fitting  10 ′ has two protrusions  60  on its outer surface  40 , extending tangential to the receiving chamber  34  and transverse to each other. The access chambers  36  extend through the two protrusions  60 . The access chambers  36 ,  38  end in the (end) surfaces  62 , extending at an acute or obtuse angle, or, as in this embodiment example, at right angles to each other and at only a small distance from each other. The locking element  44  comprises a curved front end  64  having a tip  66  in the shape of a truncated cone, and has a locking protrusion  68  at the end opposite the tip  66 . 
     As seen in  FIGS. 8 through 10 , the curved end  64  of the locking element  44  is inserted into one of the two access chambers  36 . When the locking element  44  is inserted into the access chamber  36  and the receiving chamber  34 , manual pressure can be applied to the wider end of the locking element  44  comprising the stop protrusion  68 . When the locking element  44  is nearly completely inserted in this manner, the result is the situation according to  FIG. 9 . If, starting from said situation, the locking element  44  is inserted further into the fitting  10 ′, then the stop protrusion  68  in said embodiment example engages with a detent  70  in the access opening  72  of the surface  62  of the protrusion  60 . This is shown in  FIG. 10  The stop protrusion  68  then fills the free space between the two (end) surfaces  62  and thereby contacts the outer surface of the base body  12 . The detent  70  effectively prevents the stop protrusion  68  from releasing and thus the locking element  44  from slipping out of the receiving chamber  34 . 
     As can particularly be seen in  FIGS. 7 through 10 , the stop protrusion  68  comprises a hole  74 , or simply a recess, running transverse to the extension of the locking element  44 , that can be used in order to allow tensile forces acting on the stop protrusion  68 . For example, a bar or the like can be inserted through the hole  74  and can then serve as a handle or grip, in order to pull the locking element  44  out of the fitting  10 ′ by exerting tensile forces on the locking element  44 .