Abstract:
The system includes a collar ( 10 ) and a washer ( 28 ), the collar having a tightenable band ( 12 ) suitable for co-operating with bearing surfaces ( 16, 18 ) of the interconnected tubes ( 1, 2 ) via its inside periphery defining a setback ( 14 ). The washer ( 28 ) is secured to the collar and the system further includes first pre-fitter ( 38 ) for acting when the collar is in the non-tightened state to secure the collar to the first tube when the bearing surface ( 16 ) of the first tube is engaged in the setback ( 14 ). The clamping system further includes second pre-fitter ( 40 ) for acting, when the collar ( 10 ) is secured to the first tube ( 1 ) by the first pre-fitter ( 38 ), to secure the collar to the second tube ( 2 ) when the bearing surface ( 18 ) of the second tube ( 2 ) is also engaged in the setback ( 14 ).

Description:
FIELD 
     The present invention relates to a clamping system for connecting together a first tube and a second tube. 
     BACKGROUND 
     A clamping system for connecting together a first tube and a second tube, the facing ends of the tubes having bearing surfaces that project relative to the cylindrical outside surfaces of said tubes, the system comprising a collar and a washer, the collar having a band suitable for co-operating with said bearing surfaces via its inside periphery defining a setback into which the bearing surfaces can be inserted, and means for tightening said band, the washer being secured to the collar by fastening means, the system further comprising first pre-fitting means for acting when the collar is in the non-tightened state to secure said collar to the first tube when the bearing surface of said first tube is engaged in the setback. 
     A clamping system of this type is known from European Patent No. EP 1 451 498. The cross-section of the band of the collar is, for example, substantially V-shaped or U-shaped, so that the flanges formed by the cross-sectional shape bear respectively against the bearing surface of the first tube and against the bearing surface of the second tube. Thus, tightening the collar tends to hold the tubes clamped one against the other. A V-shaped cross-section is advantageous insofar as, when the collar is tightened, it urges the tubes together. 
     For example, the means for tightening the band comprise a nut-and-bolt system. Thus, the ends of the band can be turned out so as to form bearing tabs provided with holes through which a bolt can be inserted. A nut is disposed behind one of the tabs so that turning the bolt causes the collar to be tightened. However, other tightening means may be provided, e.g. of the type operating by hooking, and in particular of the type comprising a hook that is turned out relative to the band and a lug also turned out relative to the band, the hook hooking behind the lug to maintain the collar in the tightened state. 
     The washer of the clamping system may, in particular, serve to seal the interconnection between the two tubes, by having, for this purpose, a sealing portion that, when the system is tightened onto the tubes, is sandwiched between two sealing surfaces belonging respectively to the first tube and to the second tube. 
     In EP 1 451 498, the washer is secured to the collar by means of the fastening tabs with which that washer is provided, and the entire clamping system can be held pre-fitted to the first tube, by means of the pre-fitting tabs with which the washer is provided. Thus, in order to assemble the two tubes together, it is possible to pre-fit the clamping system onto the first tube and to bring the second tube closer to the first tube, before tightening the collar. In EP 1 451 498, this possibility of pre-fitting the clamping system onto the first tube constitutes a significant advantage over the pre-existing prior art in that it simplifies assembling the tubes together and connecting them together by tightening the collar. 
     However, that assembly operation firstly requires the second tube to be held in position relative to the assembly made up of the first tube and of the clamping system as pre-fitted on said first tube, and secondly requires the collar to be tightened by performing the appropriate manipulation. In practical terms, when assembly is performed by hand, the operator must, firstly, hold the second tube in position with one hand, and secondly perform the tightening with the other hand. The operator must therefore synchronize these movements exactly and, if tightening is not readily achievable, said operator cannot let go of the second tube to complete the tightening properly. 
     SUMMARY 
     There therefore exists a need for the clamping system of EP 1 451 498 to be further improved in order to remedy the above-mentioned drawbacks and, in particular, so as to obviate the need to keep hold of the second tube in order to keep it in position while performing tightening at the same time. 
     This object is achieved by means of the fact that the clamping system of the invention further comprises second pre-fitting means for acting when the collar is secured to the first tube by the first pre-fitting means to secure said collar to the second tube when the bearing surface of said second tube is also engaged in the setback. 
     Thus, with the clamping system of the invention, the second tube can be put in position and retained in the pre-fitted state by using the second pre-fitting means. The operator can thus perform the tightening by activating the tightening means, without the operator having to hold the tubes together at the same time. 
     Advantageously, the first and/or the second pre-fitting means equip the washer. 
     The washer then serves for pre-fitting, on one and/or the other tube, without it being necessary to provide the collar or the tubes with very specific configurations. 
     Advantageously, the first pre-fitting means comprise first deformable pre-fitting tabs suitable for co-operating with the first tube. 
     Advantageously, the second pre-fitting means comprise second deformable pre-fitting tabs suitable for co-operating with the second tube. 
     Advantageously, the fastening means comprise deformable fastening tabs that are integral with the washer. 
     The washer is in general made of metal, by die-stamping, cutting-out, and folding. When manufacturing the washer, it is easy to form tabs on it that constitute first pre-fitting tabs and/or second pre-fitting tabs and/or fastening tabs. 
     In an advantageous embodiment, the fastening means, the first pre-fitting means and the second pre-fitting means are integral with the washer. 
     The washer then, by itself, forms both the first and the second pre-fitting means. 
     In another advantageous embodiment, the fastening means and the first pre-fitting means are integral with the washer, and the clamping system further comprises an additional washer, secured to the collar by additional fastening means, the second pre-fitting means being integral with the additional washer. 
     Two substantially analogous washers can then be provided or, at the least, two washers equipped with analogous pre-fitting means can be provided. For example, one of them may, in addition, serve to seal the connection between the tubes, while the other serves only to pre-fit one of the tubes relative to the clamping system. 
     Advantageously, the washer includes an annular sealing portion suitable for being sandwiched between first and second sealing surfaces belonging respectively to the first tube and to the second tube, when said tubes are clamped by means of the clamping system. 
     The washer thus has a sealing function. 
     Advantageously, the washer has a substantially frustoconical portion. 
     As explained below, it is advantageous for the tubes to co-operate with each other via frustoconical surfaces, and the washer is then adapted to match this co-operation shape. 
     Advantageously, the washer has an inside portion that extends substantially axially. 
     Advantageously, the inside portion then extends from an inside edge of the substantially frustoconical portion by forming a turned-back segment. 
     The substantially axial inside portion may serve to “cover over” the space provided under the bearing surface of the second tube, as in FR 2 906 864. Depending on its position, it can also serve to center the second tube while said second tube is being pre-fitted relative to the assembly made up of the first tube and of the clamping system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be well understood and its advantages appear more clearly on reading the following detailed description of embodiments shown by way of non-limiting example. The description refers to the accompanying drawings, in which: 
         FIGS. 1A and 1B  are axial section views of the clamping system of the invention, as pre-fitted on a first and on a second tube that are to be connected together; 
         FIG. 2  is an exploded view showing the clamping system comprising the clamping collar and a washer, as separated from each other, and also showing the first and second tubes; 
         FIG. 3  is a perspective view showing the clamping system as pre-fitted on the first tube; 
         FIG. 4  is a perspective view corresponding to the  FIG. 3  view and in which the second tube is also pre-fitted; 
         FIG. 5  is a perspective view corresponding to the  FIG. 3  and  FIG. 4  views, after the collar has been tightened, the two tubes then being connected together; 
         FIGS. 6 ,  7 A,  7 B, and  7 C are perspective views showing a washer usable in the embodiment shown in  FIGS. 1 to 5 ; 
         FIG. 8A  is an axial section view showing a clamping system using the  FIG. 7B  washer, as fitted on two tubes that are connected together by using this clamping system; 
         FIG. 8B  is a view analogous to the  FIG. 1A  view, but with a clamping system using the  FIG. 7C  washer; 
         FIG. 9  is a view analogous to the  FIG. 1A  view, for another embodiment using an additional washer; 
         FIG. 10  is a perspective view of the additional washer; and 
         FIG. 11  is a side view of the additional washer. 
     
    
    
     DETAILED DESCRIPTION 
     Firstly,  FIGS. 1A ,  1 B, and  2  are described. It can be seen in these figures that the clamping system comprises a collar  10  that is substantially of the same type as described in EP 1 451 498, and a washer  28 , the collar and the washer co-operating to assemble together two tubes  1  and  2 . 
     Throughout the description below, the term “inside” is used to describe elements that face towards the axis A of the two tubes as placed end-to-end or that are closer to that axis relative to other elements that are said to be “outside”, “outside” elements also being those that face away from the axis A. 
     The collar comprises a band  12  that, as can be seen in  FIGS. 1A and 1B , has an inside periphery that defines a setback  14  into which bearing surfaces  16  and  18  belonging respectively to the first tube  1  and to the second tube  2  can be inserted. This setback and these bearing surfaces have shapes such that tightening the band of the collar constrains the ends of the tubes to move closer together. Thus, the band  12  is advantageously V-shaped in cross-section, while the diameter of each of the bearing surfaces  16  and  18  increases gradually going towards the facing free ends of the tubes, and said bearing surfaces are, for example, frustoconical in shape. The band  12  has ends, respectively  12 A and  12 B, which are turned out substantially radially in such a manner as to form bearing tabs. These tabs are provided with holes so as to enable the shank  24 A of a bolt  24  to pass through said tabs. The head  24 B of the bolt can be wedged relative to one of the bearing tabs (tab  12 B in this example), while a nut  26  is retained relative to the other bearing tab  12 A. It can be understood that the nut being turned in the tightening direction urges the bearing tabs towards each other and thus reduces the inside diameter of the collar, i.e. makes it possible to tighten the band. 
     The clamping system further comprises the washer  28 , which is secured to the collar. The washer has a frustoconical annular portion  30  that, as can be seen in  FIGS. 1A and 1B , can be inserted between the facing ends of the two tubes when they are clamped by means of the clamping system. 
     It should be noted that the end of the tube  1  is a female end, its inside periphery being flared. Conversely, the end of the tube  2  is a male end that, beyond the bearing surface  18 , has an outside periphery  23 , the diameter of which decreases going towards the free end. The end portion formed in this way can thus be inserted, substantially with shape complementarity, inside the flare  17  formed at the free end of the tube  1 . The frustoconical portion  30  of the washer is situated between the flare  17  and the outside periphery  23  of the free end of the tube  2 . The frustoconical portion of the washer  30  has annular deformations  32  forming a sealing bead. The flare  17  formed at the inside periphery of the free end of the tube  1 , and the outside periphery of the end portion  23  of the tube  2  thus form sealing surfaces that, when the clamping system is tightened, sandwich between them the frustoconical portion  30  of the washer and press the sealing bead  32 , so that the connection between the tubes is sealed. 
     The washer can be fastened to the collar and the assembly made up of the collar and of the washer can be pre-fitted onto the first tube in the same way as in EP 1 451 498, by fastening tabs with which the washer is provided. 
     Thus, the washer has a series of inside tabs  33  that can be seen more clearly in  FIG. 1B . When the washer is assembled to the collar, these inside tabs co-operate with the inside periphery of one of the branches of the band  12 , namely the branch  13 A in this example. These inside tabs serve to keep the washer apart from the inside periphery of the branch  13 A. The fastening tabs further comprise outside tabs  34  that, as can be seen in particular in  FIGS. 1A and 1B  are long enough to come into contact with the free inside edge of the branch  13 A. The inside tabs may be raised radially slightly in the direction going towards their free ends, in such a manner that said free ends come to bear more securely against the inside periphery of the branch  13 A. Conversely, the outside tabs are directed substantially axially in such a manner as to pass under the free inside edge of the branch  13 A. It can be seen that the free ends of said outside tabs  34  curve back to form hooks  34 A that come to hook onto the outside face of the branch  13 A. 
     In this example, the outside tabs  34  also make it possible to pre-fit the clamping system on the tube  1 . It can be seen that tongues  38  are cut out from the outside tabs in such a manner as to have free ends directed towards the joining zone at which the outside tabs join the washer, while being turned radially inwards in such a manner as to hook onto the bearing surface  16  of the tube  1 . These tongues  38  thus form what might be termed “punched-out portions”, provided in the axial portions of the outside tabs  34  and folded back towards the inside so as to come to cling onto the bearing surface  16 . Naturally, provision could be made for the clinger tongues  38  to be formed in outside tabs that are not provided with hook-shaped free ends  34 A. 
     It can also be observed that, on their longitudinal edges, the outside tabs have flanges  36  that are folded back towards the inside. These folded-back flanges  36  contribute to fastening the washer relative to the collar and impart a certain amount of rigidity to the tabs  34  so as to prevent them from deforming too easily. However, the above-mentioned fastening tabs, namely the tabs  33  and  34 , deform during tightening so as to be pressed against the inside periphery of the branch  13 A of the band  12  of the collar, and thus so as not to oppose the tightening. 
     The tongues  38  of the outside tabs constitute first pre-fitting tabs that enable the assembly made up of the washer and of the collar to be pre-fitted onto the first tube  1 . Thus, the fastening means and the first pre-fitting means are integral with the washer  28 . In the embodiment shown in  FIGS. 1A to 8B , second pre-fitting means, making it possible to pre-fit the assembly made up of the collar and of the washer onto the second tube, are integral with the washer. The above-described fastening tabs  33  and  34  and the first pre-fitting tabs constituted by tongues  38  cut out from the tabs  34  are situated on a first side of the washer in a first axial direction S 1 . In this example, this first axial direction is the one that goes along the axis A away from the branch  13 B of the band  12  of the collar from the junction where this branch joins the branch  13 A. 
     In  FIGS. 1A to 8B , the second pre-fitting means comprise second pre-fitting tabs  40  that are situated on a second side of the washer, opposite from the first side, and that, in this example, extend in the axial direction S 2  from the outside periphery  28 A of the washer. In the embodiment shown, and as can be seen more clearly in  FIG. 6 , these second pre-fitting tabs  40  are formed by pre-deformed tabs that, in the axial section shown in  FIG. 1 , comprise a joining segment  41  joining to the washer and extending outwards from the washer (more precisely from the outside periphery  28 A of the washer), and a securing segment  42  for securing to the second tube  2  and that extends between the joining segment  41  and the free end  40 A of the pre-deformed tab  40  while pointing inwards in the direction going towards said free end  40 A. 
     It can also be seen that each pre-deformed tab  40  further comprises a retaining segment  43  that extends between the securing segment  42  for securing to the second tube  2  and the free end  40 A of the pre-deformed tab, while pointing outwards in the direction going towards said free end  40 A. It can be understood from  FIGS. 1A and 1B  that said retaining segment  43  can co-operate with the band  12  of the collar to retain the pre-deformed tab  40  relative to said band. In this example, the retaining segment  43  is retained against the inside edge of the second branch  13 B of the band  12 . In the example shown, all of the second pre-fitting tabs are formed by the above-described pre-deformed tabs. However, it is conceivable for the second pre-fitting tabs to comprise at least one pre-deformed tab of the above-described type, with or without the retaining segment  43 , and other tabs of simpler form, in particular extending substantially axially in the direction S 2  and being deformed merely when the bearing surface  18  of the second tube is inserted into the setback  14  formed inside the band  12  of the collar. Naturally, it is advantageous for the washer to have at least two diametrically opposite pre-deformed tabs, or indeed three or four pre-deformed tabs disposed uniformly angularly spaced apart from one another, so as to center the second tube while it is being pre-fitted relative to the assembly made up of the clamping collar and of the pre-fitted washer. 
     Advantageously, the second pre-fitting tabs include at least one tab that is of substantially constant width. In this example, in the variant shown in  FIG. 6 , the second pre-fitting tabs comprise four pre-deformed tabs  40  and all of the tabs have the same width l that is substantially constant over their entire length. 
     This also applies to the variant shown in  FIG. 7A . However, the washer  128  in this variant differs in two respects from the washer  28  that is described above with reference to  FIG. 6 . 
     Firstly, the free ends  40 A of the pre-deformed tabs  40  curve back to form hooks  44  that, when the washer  128  is fastened to the collar  10 , come to hook onto the outside periphery of the second branch  13 B of the band  12  of the collar. 
     Secondly, the washer  128  has an inside portion  50  that extends substantially axially. In this example, this washer  128  has a frustoconical portion  30  analogous to the frustoconical portion of the washer  28 , and the substantially axial inside portion  50  extends from an inside edge  30 A of the frustoconical portion  30  by forming a turned-back segment. This turned-back segment may have the same function as disclosed in FR 2 906 864 and serve to “bridge” the cavity provided at the end of the tube  2 , under the bearing surface  18  and the frustoconical free end portion. In addition, as can be seen in  FIG. 8A , the outside periphery of the inside portion  50  can come to co-operate with the free end edge of the second tube  2  so as to center the second tube relative to the washer while it is being pre-fitted. 
     The washer shown in  FIG. 7B  is analogous to the washer shown in  FIG. 6 , except that the pre-deformed tabs  40  have a width that decreases in the direction going towards to their free ends. This makes it possible to increase the flexibility of these tabs going towards their free ends, and to make provision so that, in the vicinity of said free ends, they occupy only an angular range that is relatively small. Naturally, it is possible to make provision for only one of the second pre-fitting tabs to have such a tapering width. 
       FIG. 7C  shows a variant of the washer of  FIG. 7A  that differs therefrom by the fact that the pre-deformed tabs  40  have free ends  40 A that curve back so as to cover the vertex  12 ′ of the cross-section of the collar, as can be seen more clearly in  FIG. 8B . More precisely, the washer  128 ′ shown in  FIG. 7C  differs from the washer  128  shown in  FIG. 7A  by the fact that the hooks  44 ′ are extended compared with the hooks  44  so that, when the washer is in place relative to the collar, they come against the outside face of the branch  13 B of the band  12  of the collar until they cover the vertex  12 ′ of the band that is formed at the junction where the branches  13 A and  13 B meet. Thus, the hooks  44 ′ hook onto the vertex  12 ′, the free ends  40 A of the pre-deformed tabs  40  being situated against the outside face of the branch  13 A of the band. The hooks  44 ′ thus have intermediate segments  44 ′A that curve back at  43 ′ relative to the retaining segments  43  and to the end segments  44 ′B folded back at  43 ″ relative to the intermediate segments  44 ′A and extending between said intermediate segments and the free ends  40 A. 
     In the examples shown, the second pre-fitting tabs have flat cross-sections. However, it is also possible to make provision for them to have slightly convex cross-sections, so that they adapt to match the curvature of the bearing surface  18  of the second tube with which they co-operate. They could even be more markedly convex, which would impart a certain amount of stiffness to them. 
       FIGS. 3 to 5  show various steps in assembling the clamping system with the tubes. In  FIG. 3 , which corresponds to the state shown in  FIGS. 1A and 1B , the collar is in the non-tightened state, the washer  28  being fastened relative to said collar, and the assembly made up of the collar and of the washer is pre-fitted onto the end of the first tube  1 . The two pre-fitting tabs  40  point towards the side of the collar that faces away from the first tube  1 . It can be understood that, in order to pre-fit the second tube, it suffices to engage said tube into the collar, whereupon the vertex  18 A of the bearing surface  18  co-operates with the second pre-fitting tabs  40  so as to cause them to flex outwards. By means of their resilience, these tabs then tend to flex back in once the second tube has come into position. In particular, when the second pre-fitting tabs are formed by the above-described pre-deformed tabs  40 , said tabs going over the vertex  18 A of the bearing surface  18  of the second tube at the junctions where the retaining segments  43  and the securing segments  42  meet causes the tabs  40  to move radially and resiliently outwards until the vertex  18 A comes to be received substantially at the junctions where the joining segments  41  meet the securing segments, thereby enabling the tabs  40  to move back inwards slightly under the effect of their own resilience, thereby retaining the second tube so to prevent it from being torn out in the direction going away from the first tube. 
       FIG. 4  shows the situation in which the second tube is thus pre-fitted, with the collar still not being tightened. It can be seen that the free ends  40 A of the tabs  40  are visible from the outside of the band of the collar. In this state, the two tubes are pre-assembled, by means of the clamping system that holds them in this position. Thus, the collar can be tightened with all the required attention, without it being necessary to pay attention, at the same time, to positioning the tubes correctly relative to each other. 
     In  FIG. 5 , the collar is tightened, and this tightening causes the tabs  40  to deform, which tabs then come to press against the inside periphery of the band  12 , while retracting almost entirely into the setback  14  in said band. The fitting is analogous if the washers shown in  FIGS. 7A to 7C  are used, except that, in the situation shown in  FIGS. 7A and 7C , the ends of the tabs  40  remain more visible outside the collar. 
     There follows a description of  FIGS. 9 to 11  that show a variant embodiment, using an additional washer. The washer  228  shown in  FIG. 9  is analogous to the above-described washer  28 , except that it is not provided with the second pre-fitting tabs. The second pre-fitting means are provided on an additional washer  260  that is secured to the second branch  13 B of the band  12  of the collar. 
     In this example, as can be seen in  FIG. 10 , the additional washer  260  has a frustoconical portion  262  extending radially inwards no further than to the vertex  18 A of the bearing surface  18 , when the second tube is inserted in the setback  14  provided inside the band. 
     The second pre-fitting tabs equip the washer  228 . They comprise tabs  264  that extend inwards from the inside periphery  262 A of the frustoconical portion  262 , and that then curve back outwards in such a manner as to come to be retained against the inside free edge of the second branch  13 B of the band. 
     The second pre-fitting tabs further comprise spacer tabs  266  that point substantially axially, or that are slightly turned out in such a manner as to come to bear against the inside periphery of the second branch  13 B as shown in  FIG. 11 , in which the branch  13 B of the collar is shown sketched in so as to make the explanation clearer. The free ends of the tabs  264  curve back at  264 A to come to rest against the outside periphery of the second branch  13 B. Thus, the additional washer  260  is held relative to the second branch  13 B of the collar by the action/reaction phenomenon of the spacer tabs  266  and of the hooks  264 A, and the tabs  264  serve to pre-fit the second tube  2 , their bend zones  264 B defining, at rest, a diameter less than the diameter of the vertex  18 A of the bearing surface  18  of the second tube. The tabs  264  and  266  are also deformable firstly so as to serve for pre-fitting the second tube relative to the tightening system and secondly so as not to oppose the tightening.