SYSTEM FOR COUPLING TWO TUBES

Abstract

The system comprises a clamping collar (10) having a clamping band (14) suitable for being tightened around the abutting ends (12A, 12′A) of the two tubes (12, 12′). The collar (10) has a retaining tab (30) that presents a fastener portion (32) whereby said retaining tab (30) is fastened to the band (14) of the collar and that extends substantially axially towards an attachment portion (34) of said retaining tab (30) whereby said retaining tab is suitable for being attached to the first tube (12) in the vicinity of its first end (12A).

Claims

1. A system for connecting two tubes together end to end, the system comprising a clamping collar having a clamping band suitable for being tightened around the abutting ends of the two tubes, the collar having a retaining tab that presents a fastener portion whereby said retaining tab is fastened to the band of the collar, the fastener portion extending substantially axially towards an attachment portion of said retaining tab whereby said retaining tab is suitable for being attached to the first tube in the vicinity of its first end, the retaining tab presenting an undulation situated between its fastener portion and its attachment portion.

2. The system as claimed in claim 1, wherein the undulation presents a ridge situated between the attachment portion and the fastener portion.

3. The system as claimed in claim 1, wherein the undulation projects radially.

4. The system as claimed in claim 2, wherein the undulation is inclined relative to a radial plane, such that going towards the ridge of the undulation involves going away from the fastener portion.

5. The system as claimed in claim 1, wherein the internal periphery of the collar presents a trough suitable for receiving a radial projection formed at the end of the first tube.

6. The system as claimed in claim 1, wherein the attachment portion of the retaining tab extends at a distance from the axis of the collar that is less than or equal to the internal radius of said band in the non-clamped state.

7. The system as claimed in claim 1, wherein the collar presents two ends suitable for being moved relative to each other in order to tighten the collar, and the retaining tab is substantially diametrically opposite these ends.

8. The system as claimed in claim 1, wherein the fastener portion is formed at a free end of the retaining tab remote from its attachment portion.

9. The system as claimed in claim 1, wherein the fastener portion of the retaining tab is fastened to the band of the collar by at least one of the modes of fastening comprising welding, crimping, clinching, hooking, or clipping.

10. An assembly for coupling two tubes together, the assembly comprising a system as claimed in claim 1 and a first tube having attached thereto the attachment portion of the retaining tab and suitable for being abutted with a second tube, the band of the collar extending around the end of the first tube.

11. The assembly as claimed in claim 10, wherein the attachment portion of the retaining tab is attached to the first tube by welding or brazing.

12. The assembly as claimed in claim 10, wherein the attachment portion of the retaining tab is attached to the first tube by an attachment collar.

13. The assembly as claimed in claim 10, wherein, in the non-clamped state, the band of the collar is radially spaced apart from the end of the first tube.

14. The system as claimed in claim 2, wherein the ridge is situated substantially halfway between the attachment portion and the fastener portion.

Description

[0041] The invention can be well understood and its advantages appear better on reading the following detailed description of an embodiment given by way of non-limiting example.

[0042] FIG. 1 is a perspective view showing the collar pre-attached at the end of the first tube, prior to tightening the collar;

[0043] FIG. 2 is a section view on plane II of FIG. 1, this plane being defined by the axis of the tube and by a diameter of the tube passing through the retaining tab;

[0044] FIG. 2A shows a variant for fastening the retaining tab to the band of the collar, in zone IIA of FIG. 2;

[0045] FIG. 3 is a diagrammatic end view looking along arrow III of FIG. 2;

[0046] FIG. 4 is a view analogous to FIG. 1, but showing the collar tightened and the first tube coupled to a second tube; and

[0047] FIG. 5 is a section view on plane V of FIG. 4, this plane being analogous to the plane II of FIG. 1.

[0048] The description begins with FIGS. 1 and 2, which show a clamping collar 10 pre-attached a the end 12A of a first tube 12. Specifically, the collar is generally of the same type as that described by EP 1 451 498 and EP 2 598 785. Nevertheless, it should be understood that the invention is not limited to this type of collar.

[0049] Below, the term “internal” is used to designate elements that face towards the axis A of the tube 12 or that are closer to said axis relative to other elements that are said to be “external”, “external” elements also being those that face away from the axis A.

[0050] Specifically, the collar 10 comprises a band 14 having an internal periphery that defines a trough 16 into which it is possible to insert bearing surfaces, respectively a bearing surface 18 belonging to the first tube 12 and a bearing surface 18′ belonging to the second tube 12′ (see FIG. 5). This trough and these bearing surfaces are of shapes such that tightening the band of the collar constrains the ends of the tubes to approach each other. Thus, the band 14 presents a section that is advantageously V-shaped, while the bearing surfaces 18 and 18′ are of a diameter that increases gradually going towards the free ends of tubes that are facing each other, and for example are frustoconical in shape.

[0051] The band 14 of the collar presents respective ends 14A and 14B that project substantially radially so as to form bearing tabs. These tabs are pierced so as to enable the shank 24A of a screw 24 to be passed through the tabs. The head of the screw 24 is set relative to the bearing tab 14B, while a nut 26 is held relative to the other bearing tab 14A. In the figures, the head of the screw is not visible, but it may be analogous to that shown in Documents EP 1 451 498 and EP 2 598 785. Specifically, a setting washer 26A is interposed between the bearing tab 14A and the nut 26, this washer having a notch that sets it relative to the tip of the V-shape formed by the band 14 in order to prevent it from turning relative thereto when the screw is turned.

[0052] With reference to FIG. 5, it can be seen that the end 12′A of the second tube 12′ is a female end, its internal periphery being flared. In contrast, the end 12A of the first tube 12 is a male end that, beyond the bearing surface 18, presents an outer periphery 23 of diameter that decreases going towards the free end. The end portion 12A as formed in this way can thus be inserted as a substantially complementary shape inside the flare 17 formed at the end of the tube 12′. This shape, possibly associated with a washer interposed between the external periphery 23 of the free end of the first tube and the internal periphery of the flare 17 of the second tube can serve to seal the connection between the two tubes, when the clamping system is clamped. Such a washer need not be necessary, for example if a material is selected for the two tubes that allows for a small amount of deformation of the surfaces that come into contact under the effect of the clamping, thereby providing the necessary sealing, in particular when the required level of sealing is not extremely high.

[0053] The clamping collar 10 has a retaining tab 30 that, in the pre-attached state of the collar, is fastened to the first tube 12. This tab 30 presents a fastener portion 32 whereby it is fastened to the band of the collar, and an attachment portion 34 whereby it is fastened to the tube 12. Specifically, the fastener portion 32 is in the shape of a hook having its free end pointing towards the axis A. Seen in axial section, this fastener portion presents a shape that is substantially V-shaped (seen in axial section), suitable for receiving in its recess the V-shape of the band of the collar. It can also be seen that the fastener portion 32 is specifically formed at the free end of the retaining tab remote from its attachment portion 34. The tab 30 is generally oriented substantially axially going away from its fastener portion and to its attachment portion, and it extends towards the rear of the collar, i.e. in the direction along the tube 12 going away from its end 12A.

[0054] In the free state, i.e. before pre-attachment of the collar 10 on the tube 12, or in the pre-attached state, the attachment portion 34 of the retaining tab 30 extends at a distance D1 from the axis of the collar (coinciding in the figure with the axis A of the tube 12), which distance is less than or equal to the internal diameter D2 of the band of the collar (which internal diameter is then naturally measured while the collar is in the non-clamped state).

[0055] The fastener portion 32 of the retaining tab 30 may be fastened to the band 14 by any appropriate means. Thus, it may be welded on the band, and in FIG. 2 there can be seen two spot welds 32′ situated on respective flanks of the V-shape.

[0056] As shown in FIG. 2A, it is also possible to envisage some other mode of fastening such as clinching or crimping. Thus, FIG. 2A shows the fastener portion 32 of the tab 30 presenting two notches 32″, respectively in each of the branches of the V-shape, with the material of the band 14 of the collar being forced into them in order to form projections 14″ that penetrate into the notches.

[0057] With the above-mentioned V-shape for the section of the band 14 and for the fastener portion 32 of the retaining tab 30, it is advantageous to provide a fastener point on each branch of the V-shape.

[0058] By way of example, fastening could equally well be achieved by hooking, with the notches 32″ being replaced by small hooks that penetrate into notches formed in the positions of the projections 14″, or vice versa, or by clipping, e.g. by using separate staples or clips (not shown).

[0059] In general manner, numerous modes of fastening can be envisaged, the fastening between the retaining tab and the band of the collar not being subjected to high stresses, in principle.

[0060] The collar assembly, comprising the band and the retaining tab is manipulated as a unit and can be delivered in an assembled state.

[0061] The attachment portion 34 of the retaining tab enables the collar to be attached to the first tube 12 in the pre-attached situation.

[0062] Specifically, it can be seen that the attachment portion 34 is axially oriented, being situated remote from the fastener portion 32 and being fastened against the external periphery of the tube 12. In particular, the attachment portion of the retaining tab 30 may be attached to the first tube 12 by welding, having one or more spot welds 34′.

[0063] It is nevertheless possible to envisage other ways of attaching the attachment portion to the tube. For example, as shown by chain-dotted lines, the attachment portion 34 may be secured to an attachment collar 40 that is itself attached around the tube 12. In particular, it may be a collar of the type having two ends that hook each other. Thus, this collar is initially opened in order to be passed around the tube, and is then closed and clamped against the tube. By way of example, it may be a collar of the type described in European patent Document EP 0 003 192. The attachment portion 34 of the retaining tab may be fastened to this collar by any appropriate means, in particular by welding, clipping, crimping, or clinching.

[0064] When an attachment collar 40 is used, the assembly constituted by the clamping collar 10, including the retaining tab 30, and the attachment collar 40, can be delivered as a unit and pre-attached at the end of the tube 12.

[0065] The retaining tab 30 presents an undulation 36 that is situated between its attachment portion 34 and its fastener portion 32. This undulation projects radially outside of the first tube 12. It is situated on an intermediate portion of the tab 30 that forms a transition between the attachment portion 34, which is substantially situated on the diameter of the collar, and the fastener portion 32, which is substantially situated on the running diameter of the first tube. The undulation presents a ridge 36S situated on the intermediate portion, substantially halfway between the attachment and fastener portions. Seen in a radial plane, the undulation forms a portion of a loop or of a rounded V-shape. Specifically, it is convex when seen from the outside. It can also be seen that the undulation 36 is inclined relative to a radial plane P (see FIG. 2), such that going towards the ridge 36S of the undulation, also involves going away from the fastener portion 32. Specifically, the angle of inclination α in the non-clamped state of the collar is of the order of 30 degrees to 60 degrees. This angle is measured between the plane P and a midplane M of the undulation passing through its ridge 36S. The undulation extends over the entire width of the retaining tab, which width is measured perpendicularly to the plane of FIG. 2, and thus forms a wave of the retaining tab.

[0066] The retaining tab is formed in a strip, in particular a strip of metal material that is folded and hardened in suitable manner. With reference in particular to FIGS. 2 and 4, it can be seen that both in the non-clamped state and in the clamped state of the collar, the undulation is generally contained within the radial extent of the clamping system, since the ridge 36S of the undulation projects little or not at all radially outwards beyond the ridge 32S of the hook formed at the fastener portion 32.

[0067] In the embodiment shown, a single retaining tab 30 suffices to retain the collar in the pre-attached state at the first end 12A of the tube 12. With reference to FIGS. 2 and 3, it can be seen that in the pre-attached state of the collar 10 at the end 12A of the tube 12, there is an annular space E formed between the external periphery of the tube 12 and the internal periphery of the band 14 of the collar. It can also be seen in FIG. 3 that in the pre-attached state the collar is substantially centered relative to the tube, the axis of the collar in this figure coinciding with the axis A of the tube.

[0068] Thus, the annular space E enables the end 12′A of the second tube 12′ to be inserted under the band 14 of the collar and enables the two tubes to be coupled together (see FIGS. 4 and 5).

[0069] Thus, the retaining tab 30 is sufficiently rigid to carry the band of the collar in a cantilevered-out position and to hold it correctly positioned relative to the first tube 12. Furthermore, the retaining tab 30 can be flexed elastically, firstly to facilitate pre-attachment the collar on the first tube, should that be necessary, and secondly to enable the tab to accompany the reduction in the diameter of the collar when the collar is tightened. The undulation 36 enhances this elastic flexibility. In FIG. 2 it can be seen that the undulation is open, i.e. that its two legs 36′ and 36″ that extend on either side from its ridge 36S respectively to the fastener portion 32 of the retaining tab 30 and to its attachment portion 34 for attaching to the first tube. In contrast, in FIG. 5, it can be seen that the two legs 36′ and 36″ have moved towards each other.

[0070] As mentioned above, the retaining tab may be fabricated using the same material as the band of the collar, or using a material that presents the same general mechanical properties. In particular, it may be a metal such as steel, which may be a stainless steel, depending on the application in question. For example, when the invention is applied to exhaust tubes for motor vehicles, it may be preferred to select stainless steel. In FIG. 3, it can be seen that the retaining tab covers an angular sector β of a few degrees, e.g. of the order of 2° to 10°. In numerous circumstances, if the collar has a diameter of the order of 60 millimeters (mm) to 100 mm (as happens for example when it is used for butt-joining two exhaust tubes for a vehicle engine), the retaining tab may have a width (measured in the conferential direction of the collar) that is of the order of 10 mm to 20 mm. The retaining tab may have thickness analogous to the thickness of the band of the collar. In particular, it may have a thickness of the order of 1 mm to 1.5 mm.

[0071] Once the collar is in the standby position, i.e. in the pre-attached situation, on the end 12A of the first tube 12, it can be handled as a unit together with the first tube. In order to assemble the first tube 12 with the second tube 12′, the second tube is brought towards the end 12A of the first tube and its end 12′A is inserted into the above-mentioned annular space E, after which the collar is tightened in conventional manner. Specifically, the tightening means of the collar comprise the above-mentioned screw which, when the nut is screwed onto the threaded shank of the screw, reduces the space between the bearing tabs 14A and 14B. Naturally, other tightening means could be envisaged, and in particular hooking or pinching means.