Abstract:
A connection device for making a tight connection between two ends of tubes is provided. The connection device includes a body having two symmetrical and opposite portions for engaging ends of respective tubes, and each of the portions has a hooking element to keep the tube in the connection, and a sealing element for the connection. The hooking element of each portion includes: a truncated chamber arranged in each portion; a longitudinal rib projecting into the truncated chamber; and a split ring whose ends are located on either side of the longitudinal rib. The ring is provided with an internal threading, so as to cause a blocking of the tube by any traction on the tube in a direction opposite to its direction of engagement. The ring is placed free in the truncated chamber, on one hand, and is elastically deformable, on the other. The inner diameter of the ring is smaller than the outer diameter of the tube in an unstressed or deformed state, so as to deform elastically and to grip the tube upon introduction of the tube.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of Application Ser. No. 09/532,553, filed on Mar. 22, 2000, now abandoned, the contents of which are herein incorporated by reference thereto. 
    
    
     This invention concerns the technical field of conduits, pipes or tubes, used to transport energy in electrical, optic or fluid form. 
     1. Technical Field of the Invention 
     Construction of such transportation networks, often subterranean or subaquatic, therefore requires the juxtaposition and connection of a whole series of elements, such as tubes to make a connection between two joints. 
     2. Description of the Related Art 
     Making a connection between two tubes imposes technical constraints associated on one hand with the special application (gas, telecommunications, . . . ) and, on the other hand, with the use of automatic machines for laying those tubes. The use of connection devices that resist strong traction, have compact dimensions and do not need a lot of connection time, so as not to immobilize the machinery too long, is therefore highly sought. 
     Connection devices are known that make it possible to connect tightly two ends of tubes, having an approximately cylindrical body and two symmetrical, opposing portions to engage the ends of the respective tubes, with each of the portions having hooking means to hold the tube in the connection, and sealing means for such connections; such hooking means on each portion contain: 
     a truncated chamber arranged in each portion whose large base is located near the center of the device; 
     a longitudinal rib that projects into the truncated chamber; 
     and a split ring whose ends are located on either side of the longitudinal rib; said ring is provided with threads inside, and the outer form of said ring is chosen so that at least part of its peripheral surface is supported against the truncated chamber after the end of the tube is engaged to block the tube by any traction on said tube in the opposite direction from its direction of engagement. 
     However, these devices are not suitable for laying by machine, for example by encouraging blockages when being passed in guides. They also require complex tools to be dismantled on site, for example, to put a new cable in the tube. 
     Document US-A-2 017 894 also discloses a connection device for metal pipes in which a shrink ring is subject to the action of springs built into said device. The joint action of these springs and the narrow end of the device allows the metal ring to be encrusted in the metal pipes. 
     Such an embodiment, provided for special application to metal pipes, has an inconvenient design and is structurally complex, making it difficult and expensive to manufacture. 
     In addition, the stresses of tightening the ring are applied to the end of the connection device, thus embrittling the latter in the area near the narrowed parts. 
     In addition, tubes made of plastic material are generally wound before they are laid, generating great flexural stresses. These stresses have a tendency to deform and/or round the tubes, which makes them difficult or even impossible to assemble using a connection device. 
     SUMMARY OF THE INVENTION 
     The subject of this invention is a compact connection device, provided with a fast-hooking system for the tubes to be connected that can be dismantled without any specific tool. 
     Another goal of this invention is to create a connection device that can be adapted to a potential deformation or ovalization of the circular section of the tubes, and to ensure reliable, tight assembly. 
     According to the invention, in the type of connection device concerned, the ring is located in the truncated chamber and is deformable elastically, and the inner diameter of the ring is smaller than the outer diameter of the tube in the unstressed or deformed state of said ring, in such a way as to deform elastically and to grip the tube when inserted into said tube. 
     In another embodiment of the invention, the ring has grooves extending on part of its length starting from one end and distributed radially so as to form a radial tab on the side of the end between each pair of grooves. 
     In one preferred embodiment, the threading inside each ring has a sharp ridge that can be inserted in the periphery of the tube. 
     This design makes it easier to put each tube in the connector and improves the tube-ring connection, since it adds notching to the tightening exerted by the ring. 
     Advantageously, the threads inside the two rings have reverse pitches. 
     Thus, when the connection is made, the setting in rotation of the body in one direction, simultaneously with the engagement of the tubes in the rings sets the rings in rotation and favors the introduction of the threads of the rings in the wall of the tubes. 
     This arrangement is also interesting when dismantling the device, since by rotating the body in the opposite direction, it permits simultaneous longitudinal release toward the outside of the body of the two ends of the tube. 
     In one embodiment, the body has a circular central rib whose diametric faces form stop faces for the face at the end of each tube. 
     Thus, the engagement of each tube in the body is limited by the stop on the rib, and the contact with the stop informs the operator that he can terminate the connection by pulling the tubes toward the outside to cause additional tightening of the tubes by retracting the rings cooperating with the wall of the corresponding truncated chamber. 
     The invention also concerns a subterranean or subaquatic installation conduit having at least two installation tubes and at least one connection tube. 
     The advantage of the connection device in the invention is mainly its great structural simplicity and the reduced number of parts of which it is composed. 
     This increases the reliability of the device and reduces its cost. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other characteristics and advantages will emerge from the detailed description given below with reference to the attached drawing, which shows embodiments of the connection device in the invention, given as non-limiting examples, in which: 
     FIG. 1 is an exploded view of the connection device in the invention, 
     FIG. 2 is a longitudinal sectional view of the connection device in the invention, 
     FIG. 3 shows an element in FIG. 2 enlarged, 
     FIG. 4 is a view similar to FIG. 2 when the device connects two tube ends, 
     FIG. 5 is a partial sectional view along V—V in FIG. 4, 
     FIGS. 6 and 7 are profile and front views, respectively, of another embodiment of a ring in the connection device in the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a connection device in an exploded view. The connection device is composed of a main body  1  that is approximately cylindrical and has two portions  2   a ,  2   b  synmmetrical in relation to a plane orthogonal to the longitudinal axis of said main body  1 . The first portion  2   a , following the longitudinal axis from the outside to the central part of the connection device, has an entrance chamfer  3  and an external cylindrical span  4  in which a first circular groove  4   a  is arranged. 
     The first portion  2   a  extends through a truncated chamber  5  whose large base, partially delimited by a shoulder  6 , is located toward the center of the connection device. A longitudinal rib  7  also projects to the interior of the truncated chamber  5 . 
     The shoulder  6  then extends through a central cylindrical span in which a second circular groove  8   a  is also arranged. This central cylindrical span  8  ends with a circular central rib  9  separating the two portions  2   a  and  2   b  of the cylindrical body  1 . The two portions  2   a ,  2   b  have a symmetrical configuration. The connection device in the invention also has toric joints  10  which fit into the internal grooves  4   a  and  8   a . The connection device in the invention also has a split ring  11  located in each truncated chamber  5 . Near the split, this split ring  11  has two opposite ends  11   a ,  11   b , which are supported on the longitudinal rib  7 , thus allowing said split ring  11  to slide longitudinally along said longitudinal rib  7  and to lock said split ring  11  in rotation in relation to the main body  1 . The ring  11  is thus positioned free, along the longitudinal axis y-y′ of the connection device, in the truncated chamber  5 . Its position inside the truncated chamber  5  is determined only by the end of a tube  20 , at the time of its movement in the direction of engagement or in the direction opposite the direction of engagement in the connection device. Rotation of the main body  1 , or more specifically the connection device, thus also sets the split ring  11  in rotation. The latter can advantageously be extended by more or less pushing aside the ends  11   a  and  11   b , as is the case when a tube  20  is inserted into the connection device and goes through the split ring  11 . 
     For example, the split ring  11  is made with a plastic or metal material whose elasticity allows it, starting from a non-stressed or non-deformed state of the ring  11  in which its inner diameter is smaller than the outer diameter of the tubes  20 , to deform elastically and to grip said tube  20  when it is inserted into said device. 
     Together, the truncated chamber  5 , the longitudinal rib  7 , an the split ring  11  comprise a hooking means which serves to hold the tube  20  in the connection device. 
     On the outside, the main body  1  can have external longitudinal ribs  1   a ,  1   b  designed to make the connection device easier to grasp and handle. This makes it easier to turn the connection device in the invention manually with or without a specific tool. 
     The body  1  advantageously has a particularly resistant central zone. This central zone, located between the truncated chambers  5 , has an increased thickness, and the longitudinal external ribs la make it possible to reinforce the body  1 , which can resist high pressures, for example on the order of  50  bar, in one given embodiment. 
     The split ring  11  has threads  12  on the inside with a diameter smaller than the outer diameter of the tubes  20  designed to be connected. The split rings  11  are thus supported on the tubes designed to be connected as soon as the latter are engaged in the connection device. The split rings  11 , located in the truncated chambers  5  of portions  2   a  and  2   b , respectively, have threads in the reverse direction. 
     The main body  1 , since it is made, for example, by mirror soldering two half shells obtained for example by injection of plastic material, thus generates burrs along the joint plane of said half shells. So that these burrs do not interfere with the displacement of the split ring  11  in the truncated chamber  5 , said split ring  11  is provided with two diametrically opposed longitudinal holes that are positioned on this joint plane so as to get rid of any potential tightening or jamming problem. 
     In one embodiment, the body  1  is composed of two identical molded half shells. For purposes of assembly, one of the half shells is pivoted 180° along an axis transverse to the longitudinal axis y-y′ to form a second truncated chamber  5  with a longitudinal rib  7 . Each half shell thus has only one longitudinal rib  7  (FIG. 1, for example). 
     The split ring  11  advantageously has a peripheral surface  14  whose shape is convex. This peripheral surface  11  has, for example, a spherical-type curve that allows said ring  11  to be tightened without getting jammed in the truncated chamber  5 . Said split ring  11  is obviously tightened by longitudinal displacement of said split ring  11  along longitudinal rib  7 , starting from the large conical base taking the form of the shoulder  6 . 
     FIGS. 6 and 7 show another embodiment of the ring  11 . FIG. 7 is a view along arrow F in FIG.  6 . The ring  11  has longitudinal grooves  14   a , extending over part of its length, starting from one end  14   b . The grooves  14   a  completely traverse the radial thickness of the ring  11  and open to the outside on the end  14   b . Grooves  14   a  are distributed radially in such a way as to delimit a group of radial tabs  14   c  on the side of end  14   b . Each radial tab  14   c  is thus delimited by a pair of grooves  14   a . Part of the length of ring  11  starting from the other end  14   d , opposite end  14   b , connects all the radial tabs  14   c . Ring  11  can thus be perfectly adapted to slightly deformed or ovalized tubes, thanks to the presence of grooves  14   a  and radial tabs  14   c . The latter thus make it easier to insert tube  20  into ring  11 , particularly when said tube  20  has a section that is no longer perfectly circular. 
     FIG. 2 shows a sectional view of the connection device in the invention in which the split ring  11  on the left, that is the one located in portion  2   a , is supported against shoulder  6  and on longitudinal rib  7 . In portion  2   b , the mixed line takes the form of a tube  20  engaged in the connection device and more specifically in portion  2   b . Tube  20  is engaged and comes to stop against the shoulder that forms the central circular rib  9  and thus traverses the split ring  11 . The latter is thus slightly pushed aside and rests on or comes close to the internal wall  5   a  of the truncated chamber  5 . It is thus the exterior peripheral surface  14  of the split ring  11  that goes toward the cone formed by the truncated chamber. When tube  20  is inserted in the connection device, pushing aside the split ring  11  causes a priming or starting of encrustation of the internal threading  12  in the material of which said tube  20  is composed. The interior threading  12  of the split rings  11  has, for example, a section with sharp angles, the triangle/rectangle type, to form helicoidal notches that oppose any withdrawal of tube  20  when said internal threading  12  is encrusted in the periphery of said tube  20 . 
     An example of such internal threading  12  is shown in FIG. 3, for example. 
     FIG. 4 shows a finished connection between two tubes  20  using the connection device. FIG. 4 shows a finished connection in which the tubes  20  are definitively immobilized using the connection device. A slight traction movement on each tube  20  makes it possible to move the split rings  11  to the outside, so they are re-tightened more around the tubes  20  by cooperation between the inner wall  5   a  of the truncated chambers  5  and the exterior surfaces  14 . 
     This brings about an increased encrustation of the helicoidal notches  15  in the material of which the tubes  20  are composed and ultimately result in complete blockage of the ends of the tubes  20  in the connection device. 
     With the connection device in the invention, the ends of the tubes  20 , after having been subjected to a slight withdrawal movement for locking (see FIG.  4 ), remain in the zone located between the truncated chambers  5 , namely the reinforced zone. 
     FIG. 5 shows a sectional view along line V—V in FIG.  4 . 
     Two tubes  20  are thus connected by fitting the ends of said tubes  20  together, parallel to the longitudinal axis y-y′ (see FIG.  2 ). They are made to stop against the central circular rib  9  by rotating the main body  1  in the direction opposite the one for uncoupling. This is done by making a rotational movement on the main body  1  to gradually release the ends of the tubes  20  from the internal threads  12 . This is possible because of the longitudinal ribs  7 , which make it possible to set the split rings  11  in rotation. The ends of the tubes  20  are thus simultaneously pushed toward the exterior of the connection device. They are completely uncoupled after a number of rotations of the body  1 , due to the internal threading  12  in the opposite direction of the two split rings  11 . 
     The connection device is connected to the ends of tube  20  by engaging each end in the corresponding ring  11 , potentially with relative rotation of the tube  20  in relation to the ring  11 , then, at the end of the engagement, by exerting traction on tube  20  to displace ring  11  in its truncated chamber  5  and bring about additional tightening on tube  20 . 
     The connection device in the invention has applications for connecting a tube made of a plastic material, for example, HDPE, PP or PVC. The connection device in the invention has the advantage of being able to be dismantled without any specific tool. Manual dismantling is conceivable with no problem. In addition, no specific preparation of the ends of tubes  20  is necessary to connect them. The connection device also has great mechanical resistance without increasing its space requirements. The use of an automatic positioning machine is therefore fully indicated. 
     The connection device in the invention is also interesting, because the two tubes  20  are connected extremely quickly, without changing the reliability of such a connection. Indeed, the presence of the central circular rib  9  makes it possible to indicate to the user of such a connection how far it is necessary to insert the ends of the tubes  20  to obtain a satisfactory connection. The ends of the tubes  20  are consequently engaged up to the stop on said ends against the central circular rib  9 . 
     In addition, the longitudinal cylindrical spans  4  and  8  make possible longitudinal guidance of the tubes  20 , and their relatively large dimensions make it possible to provide a seal, even with the high radii of curvature to which the unit composed of tubes  20  and the connection device can be subject. The joints  10 , for example toric joints, make it possible to provide that seal in cooperation with spans  1  and  8 . 
     In particular, joint  10 , housed in the circular groove la of the external span  4 , makes it possible to obtain gradual radii of curvature for the tubes  20  connected, by preserving the seal and delaying the appearance of the “scaling effect” for said tubes  20 . 
     The shape of the connection device and, more specifically, the tapering shape of the body  1  also make it possible to use it in a strand of tubes, which is particularly advantageous. 
     It is therefore not difficult to conceive of using it on single- and multi-tube plowing machines.