Clamping system for connecting pipes comprising a collar and a seal

Abstract

A clamping system is provided for connecting a first tube and a second tube, the opposite ends of the first tube and the second tube having bearing surfaces protruding relative to their cylindrical outer surfaces. The clamping system comprises a clampable collar (10) and a seal (20). The collar comprises a band (12) capable of interacting with the bearing surface of the tube via its inner periphery, the inner periphery defining a reinforcement into which the bearing surface can be inserted. The seal (20) is supported by the collar in its unclamped state and comprises an annular sealing portion (21) comprising a metal washer (22) and a non-metallic-based washer (24) fixed to the metal washer. The metal washer may be provided with support lugs (30, 32) to support the washer relative to the collar.

Description

Technical Field

[0001] The invention relates to a clamping system for connecting a first pipe and a second pipe, the opposite ends of which have bearing surfaces projecting relative to the cylindrical outer surfaces of the pipes, the system comprising a collar and a seal, the collar being capable of being clamped around the bearing surfaces of the pipes. Background Art

[0002] Patents EP 1 451 498, EP 2 598 785, and EP 3 232 107 disclose clamping systems comprising a collar having a band that can be clamped by reducing its diameter and a seal pre-installed in the collar. More specifically, the system comprises a gasket comprising a closed annular portion forming a seal and lugs connecting the seal to the collar. The closed annular seal is initially held relative to the collar's band, with a space provided between the seal and the inner periphery of the band, thereby allowing the end of the pipe to engage between the seal and the band. The inner pipe itself is then engaged to contact the seal. This device is particularly suitable for clamping two pipes that are assembled together and have radially projecting surfaces that serve as bearings for the clamping collar. The clamping collar includes recesses that accommodate these radially projecting surfaces, and the closed annular seal itself has a shape that is adapted to these projections.

[0003] In particular, such a seal may be made of a metal of the stainless steel type and of a band of collars.

[0004] US Patent 4,185,858 also discloses a clamping system comprising a clamping collar and a seal located in two parts. This seal comprises a metal support washer and a compressible bead made of silicone rubber incorporated into the washer. Only the bead ensures the seal, while the washer merely serves to support the bead. Summary of the Invention

[0005] For some applications, particularly in the automotive sector, and especially for exhaust lines of internal combustion engines, there is a need to improve seals of the aforementioned type so that they can withstand increasingly high temperatures. Indeed, with technological advancements, it is possible that pipe temperatures, particularly those in contact with the seal, can reach several hundred degrees Celsius, for example, 900°C or even higher. However, at these temperatures, combined with high clamping stresses, the metal material of the seal loses some of the elasticity necessary to maintain the seal. Thicker metal seals can ensure a seal under high temperatures and clamping stresses, but they are expensive, heavy, and less effective in cold weather. Therefore, if a clamping system is used to connect two pipes forming part of the exhaust line of a vehicle's hot engine, such thick seals will be virtually ineffective during engine start-up.

[0006] The present invention aims to at least substantially overcome the above-mentioned disadvantages.

[0007] The present invention therefore relates to a clamping system for connecting a first pipe and a second pipe, the opposite ends of which have bearing surfaces projecting relative to the cylindrical outer surface of the pipes, the system comprising a clampable collar and a seal, the collar comprising a band capable of delimiting, by its inner periphery, a groove together with the bearing surface into which the bearing surface can be inserted, the seal being supported by the collar in its unclamped state and comprising an annular sealing portion comprising a metal gasket and a non-metallic gasket fixed to the metal gasket. The non-metallic gasket is formed of a composite material.

[0008] Optionally, the metal washer is provided with a support lug, by which the metal washer and the non-metal-based washer are supported relative to the collar.

[0009] Optionally, at least some of the support lugs are formed integrally with the metal washer.

[0010] Alternatively, the metal washer has a stamped frusto-conical surface and the non-metal based washer is formed as a planar ring that can be deformed to match the frusto-conical shape of the frusto-conical surface.

[0011] Optionally, the non-metal based washer is bonded to the metal washer.

[0012] Optionally, the metal washer is provided with securing lugs that cooperate with the non-metallic based washer to secure the non-metallic based washer relative to the metal washer.

[0013] Optionally, the fixing lug is cut out in the metal washer.

[0014] Optionally, the non-metal based gasket is formed from a mica based material.

[0015] Alternatively, the non-metallic based gasket comprises mineral particles, particularly mica or graphite, and a binder.

[0016] Optionally, the non-metallic based gasket comprises a reinforcement, in particular a metal reinforcement.

[0017] Optionally, the metal washer has an annular protrusion on a first face of the metal washer, and the non-metallic based washer is disposed against the first face.

[0018] Optionally, the non-metallic based gasket has an annular protrusion on its first face, and the first face of the metal gasket and the first face of the non-metallic based gasket are arranged against each other so that the annular protrusion can contact.

[0019] Optionally, the non-metal-based gasket further has an annular protrusion on the second surface thereof, and the annular protrusions of the non-metal-based gasket optionally jointly define an annular space.

[0020] Optionally, the annular sealing portion further comprises an additional non-metal based gasket secured to the metal gasket such that the metal gasket is located between the non-metal based gasket and the additional non-metal based gasket.

[0021] According to the invention, the seal of the clamping system thus comprises two gaskets fixed together, one being a metal-based gasket and the other being a non-metallic-based gasket. The combination of these two gaskets can be loaded relative to the collar by means of an appropriate configuration of the seal. The portion required for sealing, namely the annular sealing portion comprising the metal gasket and the non-metallic-based gasket, can be easily shaped to meet the sealing requirements while taking into account the clamping stresses and the relevant temperature levels. This annular sealing portion is intended to be arranged between the opposing surfaces of the pipes connected using the clamping system and to be clamped by clamping between these surfaces during the clamping of the collar. In particular, the non-metallic-based gasket may comprise a material, in particular a mica-based material, suitable for maintaining elastic deformability at high temperatures and facilitating sealing over a wide temperature range and stress range. The seal can be lightweight, with the metal gasket portion imparting strength and mechanical resistance, while the non-metallic-based portion contributes to its effectiveness, in particular in the high temperature and high pressure ranges. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a perspective view of a clamping system according to the invention seen from a first side.

[0023] Figure 2 yes Figure 1 A perspective view of the system shown, seen from the other side.

[0024] Figure 3 is an exploded perspective view showing the different elements making up the clamping system, represented separately, and the ends of two tubes to be assembled using this system.

[0025] Figure 4 is Figure 1 , an axial section in plane IV of , shows, on the one hand, a clamping system according to the invention and, on the other hand, the ends of two tubes to be assembled using the clamping system.

[0026] Figure 5 yes Figure 1 An enlarged view of detail V is shown in FIG.

[0027] Figure 6 yes Figure 2 An enlarged view of detail VI is shown in FIG.

[0028] Figure 7 yes Figure 4 Detail VII shown in FIG.

[0029] Figure 8is an alternative embodiment with Figure 4 Similar partial axial cross-section.

[0030] Figure 9 is a partial perspective view showing a variation of the seal. DETAILED DESCRIPTION

[0031] Figure 1 A clamping collar 10 is shown, comprising a band 12, the ends of which are radially raised to form clamping lugs 12A and 12B, respectively. To clamp the collar, the diameter of the band is reduced by engaging a clamping screw 14 with the clamping lugs 12A and 12B. The shank 14B of the screw passes through a hole in the clamping lug, its head 14A engages with lug 12A, and the opposite end is provided with a nut 14C, which in this case engages with lug 12B via a spacer 14D.

[0032] The belt 12 has an inner groove 15 (at Figure 4 (more obvious in FIG). The seal 20 is arranged inside the belt. Figure 4 As shown, this clamping system is used to connect two tubes 1 and 2, each of which has bearing surfaces 1A and 2A at its ends. To connect these tubes, their ends are brought together until they are axially seated in groove 15, and the diameter of the band is reduced so that the flanks 12C and 12D press against the bearing surfaces 1A and 2A. In this case, the bearing surfaces 1A and 2A are formed on radial flanges provided at the ends of tubes 1 and 2. As shown in the figure, a seal 20 is positioned inside the collar. To connect tubes 1 and 2, the front surfaces 1'A and 2'A of the ends of tubes 1A and 2A are placed on either side of an annular sealing portion 21 provided by seal 20.

[0033] Within the meaning of the present invention, the forward direction of a tube 1 or 2 is the direction toward the other tube 2 or 1 when their ends are brought together to assemble the tubes. Thus, the bearing surfaces 1A and 2A are formed on radial flanges present at the ends of the tubes. The rearward direction is obviously the opposite direction. For the element, the inward direction is the direction toward the axis A. The outward direction is the opposite.

[0034] The annular sealing portion includes a metal gasket 22 and a non-metallic base gasket 24 fixed to the metal gasket. Figure 1 、 Figure 2 and Figure 3 As understood, the annular sealing portion includes a metal gasket 22, a non-metallic gasket 24 disposed on a first side of the metal gasket, and another non-metallic gasket 26 disposed on the other side of the metal gasket. Thus, the metal gasket 22 is sandwiched between the non-metallic gaskets 24 and 26.

[0035] For example, the metal washer 22 can be made of the same metal as the belt 12, such as stainless steel. The non-metallic washers 24, 26 can be formed from a composite material. They can be formed from a mica-based material. The non-metallic washers can contain mineral particles (particularly mica or graphite) and a binder. The non-metallic washers can include a reinforcement, particularly a metal reinforcement, to support the non-metallic material, particularly a mica- or graphite-based composite material. For example, the reinforcement can be a fine wire mesh.

[0036] The gasket 24 or 26 is "non-metal-based" in the sense that the gasket does not include metal, or if it includes metal, such as a metal reinforcement, the mass of the metal accounts for only a small portion of the gasket, for example, the mass of the metal does not exceed 40% of the mass of the gasket, and in particular does not exceed 20% or 30%.

[0037] The non-metallic based washers 24 and 26 are supported by the metal washer 22. Thus, if Figures 1 to 3 As shown, the metal washer 22 is provided with support lugs by which the metal and non-metallic based washers are supported relative to the collar 10. The seal is thus pre-mounted in the band, that is, supported by the collar before the collar is placed on the pipe and clamped, so that the collar and seal can be handled as a unit.

[0038] Furthermore, the metal gasket can also be provided with supporting lugs for pre-installing the collar equipped with the gasket on one of the pipes to be assembled. Thus, the assembly formed by the collar and the seal can be placed at the end of one pipe and kept there until the end of the other pipe is placed and the collar is clamped. The same lugs can have a dual function, namely, for pre-installing the seal in the band and for pre-installing the assembly formed by the collar and the seal on the end of one of the pipes. These supporting lugs are supported by the outer periphery of the metal gasket 22 (away from the axis A of the band).

[0039] In this case, three different types of lugs are shown. Figure 7 and Figure 9 As can be better seen in FIG, the support lugs 30 have hook-shaped bent ends 30A so as to be able to hook onto the edge 13 of the flank 12C of the strip 12. Between the connection area of these lugs 30 with the periphery 22 ′ of the metal washer 22 and the hooks 30A, these lugs 30 have an axial section 30B that extends substantially axially, that is to say substantially parallel to the axis A. As shown in FIG. Figure 7 As can be seen better in FIG. 3 , on the one hand, the axial section 30B has a hooking tab 30C cut out in the axial section 30B and folded radially inwards by extending in the direction from the hook 30A to the outer periphery 22 ′ of the metal washer 22 towards its free end. The tab 30C serves to grip the washer on the bearing surface 1A of the pipe 1 in order to retain the collar pre-mounted on the end of this pipe. As can be seen, according to Figure 4As shown by arrows R1 in FIG, the orientation of these tabs 30C prevents the tube from being disengaged from the gasket in the rearward direction of the tube 1 .

[0040] Furthermore, the support lug 30 has wings 30D that are folded radially outward from the longitudinal edges of the axial section 30B, that is, so as to be moved away from the axis A. Furthermore, when the seal is pre-installed in the gasket, the wings 30D have retaining edges 30D' that face the inner surface of the hook 30A and, therefore, the inner surface of the flank 12C of the band 12. These retaining edges 30D' are spaced apart from the inner surface of the hook 30A. The edge 13 of the flank 12C is accommodated in the space thus arranged between the hook 30A and the retaining edge 30D. This makes it possible to fix the metal gasket 22 relative to the band of the collar by retaining it in both axial directions.

[0041] The support lugs also include lugs 32, which also have hooks 32A at their free ends (opposite the area where they are attached to the outer periphery 22' of the gasket 22). These lugs 32 also include axial sections 32B that extend substantially axially between the attachment of these lugs to the gasket 22 and the hooks 32A. These lugs 32 also have hooking tabs 32C similar to the tabs 30C described above. Finally, these lugs 32 also include wings 32D, but with an orientation opposite to that of the aforementioned wings 30D. In fact, the wings 32D are folded radially inward from the longitudinal edges of the axial sections 32B. These wings 32D have longitudinal edges 32D' that help to maintain the pre-installed collar on the end of the pipe 1 by maintaining the gasket in radial displacement relative to the pipe.

[0042] The metal washer also has lugs 34, such as Figure 1 and 3 As shown, the lugs 34 have hooks 34A at their free ends (opposite the periphery 22 ′ of the washer 22) and axial sections extending from the washer towards these hooks. These lugs serve for the angular wedging of the washer relative to the belt, the hooks 34A engaging in notches 13A present in the edge 13 of the flank 12C of the belt.

[0043] Typically, support lugs 30 and support lugs 32 are alternately provided on the periphery of the gasket 22. These lugs 30 and 32 are used to prevent the seal from moving relative to the belt edge and Figure 4 The lugs 30D are arranged to move in a direction opposite to the direction R1 shown and to hook onto the edge 13 of the lateral wing 12C of the belt 12. The wing 30D serves to retain the gasket relative to the belt by limiting its movement relative to the belt in the direction R1. These lugs, as well as the lug 32, also have tabs 30C or 32C for retaining the end of the tube within the gasket. The lug 32 also has a wing 32D for centering the tube relative to the gasket.

[0044] Especially if Figure 3Shown, support lug 30 and 32 are formed into one with the metal washer.In fact, this metal washer is formed into one by cutting, punching and bending by a band.

[0045] exist Figures 1 to 4 In the example shown, the metallic washer 22 and the non-metallic washers 24 and 26 are substantially planar. In practice, the front faces 1 'A and 2 'A of the flanges form bearing surfaces for the tubes 1 and 2 , which are radially oriented thereon.

[0046] However, as indicated for example in patents EP 1 451 498, EP 2 598 785 or EP 3 232 107, the collar can be pre-mounted on a tube whose bearing surface is frustoconical. Figure 8 As shown, the metal washer 122 may have a frustoconical surface, in particular a stamped frustoconical surface. Figure 8 The cross-section of FIG shows seal 120 with a gasket 122 and lugs 30, 32, and 34 similar to those previously described. Band 112 is similar to band 12, but its flanks 112C and 112B are angled like V-shaped branches to accommodate the flaring of tubes 101 and 102. In practice, support surface 101A of tube 101 has a frustoconical shape that forms the flaring, while support surface 102A of tube 102 has a front face 102'A that also forms a frustoconical surface to accommodate the aforementioned flaring. Support surface 102A, formed rearwardly in direction R2 relative to frustoconical portion 102'A, is also frustoconical in the opposite direction, substantially parallel to flanks 112B of band 112. As shown, the metal gasket has a stamped frustoconical surface 122A that conforms to the shape of the surfaces 101'A and 102'A of the tubes to which the seal 120 must be sealed. A portion of the non-metallic-based gasket 124 is formed as a planar ring that can be deformed to match the frustoconical shape of the frustoconical surface of the metal gasket 122.

[0047] Since the gasket 124 is made of a non-metallic material, it cannot always be stamped. For reasons of manufacturing cost, it is advantageous to form it from a planar plate. However, to some extent, the initially planar (planar manufactured) non-metallic gasket can be deformed to match the frustoconical shape of the surface 122A of the gasket 122.

[0048] For example, for an initially planar non-metallic gasket, the angle α formed by the aforementioned frustoconical surface of the tube with respect to the direction perpendicular to the axis A is at most 20°. A larger angle of 45° can be obtained, for example, by using a non-metallic gasket that is not initially planar but can be correspondingly shaped, for example by heating (in particular when it is a gasket containing a thermoformable adhesive).

[0049] Unlike the metal gasket 22, the non-metallic-based gasket 24 can be purely annular, without fixing lugs or the like. The non-metallic-based gasket is supported by the metal gasket 22. It can be fixed to the metal gasket in different ways. For example, it can be fixed to the metal gasket by bonding. This bonding can involve the entire contact surface between the gaskets 22 and 24, or, on the contrary, can be carried out by a continuous or discontinuous adhesive strip with a smaller surface. For example, a cyanoacrylate-type glue can be used. This glue can evaporate in particular at high temperatures, such as those to which the clamping systems used in the exhaust lines of internal combustion engines may be subjected. The glue can be applied during the assembly of the gasket or can be pre-adhered to the non-metallic-based gasket like an adhesive, possibly covered with a peelable film.

[0050] The non-metallic based washer 24 can be supported by the metal washer 22 by purely mechanical means without the use of external materials such as glue. Thus, the metal washer can be provided with fixing lugs that cooperate with the non-metallic based washer to fix it relative to the metal washer. Figure 1 and Figure 5 In FIG. 1 , it can be seen that the metal washer 22 has lugs 36 formed by a cutout of the washer which is straightened in the axial direction to form a tab whose free end is oriented toward the axis A. These fixing lugs 36 are thus used to wedge and fix the non-metallic base washer 24 by cooperating with the outer radial edge 24A of the non-metallic base washer 24. Similarly, as Figure 2 and Figure 6 As shown, the metallic washer 22 has a retaining lug 38 that is similar to the retaining lug 36 but is axially oriented on the other side to retain the non-metallic based washer 26 on the other surface of the washer 22 .

[0051] In this example, the retaining lugs 36 and 38 secure the washers 24 and 26 by means of their outer radial edges. Of course, similar lugs could also be provided that secure these washers by means of their inner radial edges, or a combination of lugs that cooperate with both the inner and outer radial edges of the washers 24 and 26.

[0052] The metal washer 22 may have an annular protrusion, or generally an annular protrusion, to impart the ability to deform axially. Figure 3In the figure, gasket 22 can be seen to have an annular bead 22A protruding from one face of the gasket, against which non-metallic gasket 24 is positioned. Non-metallic gasket 24 or 26 can be completely planar. Alternatively, it can have an annular projection 24A, specifically one with a convexity that is opposite to that of annular projection 22A of gasket 22 and a diameter that corresponds to that of projection 22A. In this case, when gasket 24 is assembled onto gasket 22, their respective projections can contact via their convex faces, allowing the gasket to axially deform under clamping force in the region of the projection to ensure a good seal. Gasket 26 can also have an annular projection 26A, which can be oriented in a similar direction to annular projection 22A, so as to partially "embed" the projection. In this case, it is more accurate to say that it is a region of the gasket rather than a projection that deforms under clamping force. These projections can also be oriented in opposite directions. Thus, if we consider the gaskets 22 and 24 just described, we can see that the annular projections on their respective first faces are arranged against each other so that these annular projections can contact. A reverse situation can also be provided, wherein the annular projection 22A of gasket 22 is oriented in the opposite direction, i.e., in the direction of forming a hollow on the side of the non-metallic gasket 24, and the non-metallic gasket 24 has an annular projection protruding on the opposite side of gasket 22 with its concave surface facing gasket 22. Thus, the two annular projections are arranged on opposite faces of the gaskets, and when they are coupled, the corresponding annular projections together define a concave annular space. This is another way to promote axial deformation of the gasket to promote sealing.

[0053] Figure 9 An example is shown in which the non-metallic-based gasket 124 is actually formed by two simple gaskets 123 and 123' fixed together, for example, by bonding. Each of these simple gaskets 123 and 123' has an annular protrusion 123A and 123B, respectively. Therefore, the gasket 124 has an annular protrusion not only on its first face facing the metal gasket 22, but also on the opposite second face. The annular protrusions 123A and 123B are arranged on the same diameter size so that an annular space 124' is provided between them. Figure 9 It can also be seen in FIG. 1 that the metal washer 22 has an annular protrusion 22A protruding on a first face thereof, against which the washer 124 is disposed, such that the annular protrusions 22A and 123A are disposed in abutment with each other.

[0054] Instead of a purely convex annular protrusion, the metal washer 22 may have a wave or deformation forming a slight curvature so that the inner and outer radial edges of the metal washer are slightly spaced axially apart. This may be done, for example, in Figure 72B, wherein the metal washer 22 has such a slight bend 22B. The non-metallic based washers 24 and 26 disposed on either side of the metal washer 22 may initially be planar and may deform to accommodate the bend during the clamping of the collar, or may initially have such a bend.

[0055] The projections, bends or protrusions of the non-metal-based gasket (or simple gasket) may be formed by any suitable means, such as by thermoforming, particularly when the material from which the gasket is formed includes a thermoformable adhesive.

[0056] In the area where no protrusions are present, the thickness of the metal washer 22 measured axially between its two faces is, for example, of the order of 0.2 to 0.8 mm, in particular 0.2 to 0.4 mm. The thickness of the non-metallic-based washer, measured in the same manner, may be 50% to 200%, in particular 120% to 200%, of the thickness of the metal washer.

Claims

1. A clamping system for connecting a first tube and a second tube (1, 2), the opposite ends of the first and second tubes having bearing surfaces (1'A, 2'A) protruding relative to the cylindrical outer surfaces of the tubes, the system comprising a clampable collar (10) and a sealing element (20), the collar comprising a band (12) capable of defining, through its inner periphery, together with the bearing surface, a groove (15) into which the bearing surface can be inserted, the sealing element being supported by the collar in an unclamped state of the collar and comprising an annular sealing portion (21), the annular sealing portion comprising a metal gasket (22, 122) and a non-metallic-based gasket (24, 124) fixed to the metal gasket, the non-metallic-based gasket (24, 124) being formed of a composite material.

2. The clamping system according to claim 1, wherein: The metal washer (22, 122) is provided with support lugs (30, 32), and the metal washer and the non-metal-based washer (24, 124) are supported relative to the collar by the support lugs.

3. The clamping system according to claim 2, wherein: At least some of the support lugs (30, 32) are formed integrally with the metal washer.

4. The clamping system according to claim 1, wherein: The metal washer (122) has a stamped frustoconical surface, and the non-metal-based washer (24) is formed as a planar ring that is deformed to match the frustoconical shape of the frustoconical surface.

5. The clamping system of claim 1 , wherein: The non-metal-based gasket (24, 124) is bonded to the metal gasket (22, 122).

6. The clamping system of claim 1 , wherein: The metal washer (22, 122) has a fixing lug (36) that cooperates with the non-metal-based washer (24, 124) to fix the non-metal-based washer relative to the metal washer.

7. The clamping system of claim 6, wherein: The fixing lugs (36) are cut out in the metal washer.

8. The clamping system of claim 1 , wherein: The non-metal-based gasket (24, 124) is formed from a mica-based material.

9. The clamping system of claim 1 , wherein: The non-metallic-based gasket (24, 124) comprises mineral particles and a binder.

10. The clamping system of claim 9, wherein: The mineral particles include one or more of mica and graphite.

11. The clamping system of claim 1 , wherein: The non-metallic based gasket (24, 124) includes a reinforcement.

12. The clamping system of claim 11, wherein: The non-metallic based gasket (24, 124) includes a metal reinforcement.

13. The clamping system of claim 1 , wherein: The metal washer (22) has an annular protrusion (22A) on a first surface of the metal washer, and the non-metal-based washer (24) is arranged against the first surface.

14. The clamping system of claim 13, wherein: The non-metallic-based gasket (24, 124) has a first annular protrusion (24A, 123A) on a first face of the non-metallic-based gasket, and the first face of the metal gasket and the first face of the non-metallic-based gasket are arranged against each other so that the annular protrusions are in contact.

15. The clamping system of claim 14, wherein: The non-metal-based gasket (124) also has a second annular protrusion (123B) on its second surface.

16. The clamping system of claim 15, wherein: The first annular protrusion (123A) and the second annular protrusion (123B) of the non-metallic-based gasket (124) jointly define an annular space (124').

17. The clamping system of claim 1, wherein: The annular sealing portion (21) further comprises an additional non-metallic based gasket (26) fixed to the metal gasket (22) such that the metal gasket is located between the non-metallic based gasket and the additional non-metallic based gasket.

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