FR2906864A1 - Clamping system for sealed connection of e.g. exhaust gas tubes, has washer with sealed portion arranged between sealing surfaces of respective tubes, and cylindrical return axially extending from and connected to inner edge of portion - Google Patents

Abstract

The system has a clamp including a band (12) with an inner periphery co-operating with support surfaces (16, 18) of opposed ends of tubes. The periphery delimits a recess, and clamping units clamp the band. A washer (28) has a truncated conical sealed portion (30) arranged between sealing surfaces of the respective tubes. The washer has an inner cylindrical return (32) axially extending from and connected to an inner edge (30') of the sealed portion. An independent claim is also included for a tube assembly comprising two tubes and a clamping system.

Description

The present invention relates to a clamping system for connection

  sealing two tubes whose opposite ends have bearing surfaces projecting from the cylindrical outer surface of said tubes. The system comprises a collar and a washer, the collar comprising a band adapted to cooperate with said bearing surfaces by its inner periphery which delimits a recess and means for clamping said strip, the washer comprising a sealing portion adapted to be disposed between sealing surfaces respectively belonging to each of the two tubes. A clamping system of this type is known from PCT patent application WO 03/048624. The section of the band of the collar is for example V-shaped or U, so that the wings formed by this section respectively bear on the bearing surface of each end of the tubes. Thus, the tightening of the collar tends to hold the tubes against each other. The shape section of V or U has the advantage of causing a reconciliation of the tubes against each other, during clamping of the collar.

  The means for clamping the band of the collar comprise for example a screw system, of the type described in PCT applications WO 03/048624 or WO 2005/057071. The washer serves to provide a tight connection between the two tubes when, its sealing portion being disposed between the sealing surfaces of the tubes, the collar is tightened. The system known from PCT application WO 03/048624 is satisfactory, in particular because it is easy to handle insofar as the washer is secured to the collar, so that these two parts can be manipulated as a whole.

  The tubes assembled using the clamping system according to the invention are used for conveying a fluid, in particular the exhaust gases of a heat engine. Due to the formation of the bearing surfaces at the ends facing the two tubes, the inner surface of the latter often has irregularities in this region. In particular, the bearing surfaces protruding radially, they can be obtained by radial deformations of the tubes, reflecting, on the inner periphery of at least one of them, by the presence of a hollow throat. Indeed, for example, the bearing surface of the first tube is formed by a flare at the free end of said tube, while the second tube has, arranged successively towards its free end, a flare forming the surface of the tube. support of the second tube and a necking which, with said flare, forms a groove on the inner periphery of the second tube. The presence of such irregularities, in particular such a hollow groove, provides a non-laminar flow area for the fluid conveyed into the tubes. This results in local turbulence, which disturbs the flow and can cause noise or vibration. The invention aims to improve this situation.

This object is achieved by the fact that the washer further comprises an internal cylindrical return which extends axially by being connected to the inner edge of said sealing portion. Thus, according to the invention, the presence of the washer is used to improve the regularity of the inner surface of the tubes, in the region 20 of their assembled ends. In particular, the internal cylindrical return may allow substantially to cover the aforementioned recessed groove to prevent or limit the tendency of the fluid to enter this groove by causing turbulence. The internal cylindrical return extends from the inner edge of the washer which is, of course, chosen so that its dimensions are suitable for those of the assembly, which is particularly the case when this inner edge is situated on substantially the same diameter than the inner surface of the tubes (more precisely, on a diameter slightly less than that of this inner surface, the difference between the two diameters corresponding to the thickness of the cylindrical return). The fact that the internal cylindrical return is secured to the washer improves the flow of fluid in the tubes, without having to change the conformation of the latter or to fix a part other than the washer and the clamp.

Advantageously, the sealing portion is of generally frustoconical shape and the cylindrical return forms, in axial section, an acute angle with said sealing portion. Thus, the general shape of the washer is simple, so that its manufacture is not significantly complicated by the presence of the cylindrical return. Advantageously, the washer is adapted to be secured to at least one of the elements constituted by the band of the collar and by one of the tubes. This may be due to the shape of the washer, which allows it to fit at the end of one of the tubes and / or by a development of this washer such as brackets. This allows easy assembly of the assembly consisting of the collar and the washer on the tubes. For example, the washer may be integral with the collar and thus be properly positioned relative to the tubes simply by positioning the collar on the tubes. In this case, the positioning of the cylindrical return relative to the tubes requires no other operation than the positioning of the collar, which carries the washer. One can also choose to secure the washer with one of the tubes, then bring the other tube thereof, and set up 20 the collar. In this case, the positioning of the cylindrical return relative to the tubes requires no other operation than the positioning of the washer. Advantageously, the washer has tabs that extend from the outer edge of the sealing portion.

Depending on their length and shape, these tabs may be used to center the washer relative to one of the tubes and / or to attach it to the band of the collar. Thus, advantageously, these lugs comprise centering lugs, which are capable of cooperating with the top of the flare of one of the two tubes and / or the fixing lugs, which are capable of cooperating with the band of the collar. to hold the puck in relation to this tape. The invention also relates to a tube assembly comprising a first and a second tube whose facing ends have bearing surfaces protruding from the cylindrical outer surface of said tubes and a clamping system comprising a collar and a washer. , the bearing surface of the first tube 2906864 4 being formed by a flare at the free end of said tube, while the second tube has, arranged successively towards its free end, a flare forming the bearing surface of this second tube and a necking which, with said flare, forms a groove on the inner surface 5 of the second tube, the washer comprising a sealing portion which is disposed between sealing surfaces of the tubes respectively formed by the inner periphery of the tube; flared the first tube and the outer periphery of the necking of the second tube which is engaged in the flare of the first tube.

According to the invention, the washer further comprises an internal cylindrical return which extends axially by being connected to the inner edge of said sealing portion and which covers at least substantially said groove. Advantageously, the assembly comprises means for securing the washer with one of the elements constituted by the band of the collar and by one of the tubes. The invention will be better understood and its advantages will become more apparent on reading the following detailed description of an embodiment shown by way of non-limiting example.

The description refers to the accompanying drawings in which: - Figure 1 is an axial sectional view of an assembly according to the invention; - Figure 2 is an elevational view of a clamping system according to the invention; Figure 3 is an enlargement of Figure 1 in the region of the connection between the tubes; - Figure 4 is a perspective view of the washer; - Figure 5 is an axial sectional view of the washer, along the line V-V of Figure 6; Figure 6 is an end view of a washer; FIG. 7 is an enlargement of detail VII of FIG. 5; - Figure 8 corresponds to the view of Figure 3, with a washer made according to an alternative embodiment; Figure 9 is a perspective view of the washer according to the variant; and 2906864 - Figures 10 and 11 respectively correspond to Figures 8 and 9, for a washer according to another variant. The clamping system comprises a collar 10, generally of the same type as that described in patent applications EP 0 305 232, WO 03/048624 and WO 2005/057071. As seen in particular in Figures 1 to 3, this collar comprises a strip 12, the inner periphery defines a recess 14 in which bearing surfaces, respectively 16 and 18 belonging to the ends of two tubes, respectively 20 and 22 , can be inserted. This recess and these bearing surfaces have such shapes that the clamping of the band of the collar forces the ends of the tubes to move towards one another. Thus, the strip 12 has a substantially biconical inner surface, i.e., it advantageously has a V-shaped section, while the bearing surfaces have a diameter which increases gradually towards the free ends of the tubes and are for example of frustoconical shape. More specifically, the bearing surface 16 of the first tube 20 is formed by a flare located at the free end of this tube, while the second tube 22 has a flare 18 which forms its bearing surface and a necking 19 which is arranged after the flare in the direction towards the free end of this second tube. Thus, considered together, the flare 18 and the constriction 19 form a groove 24 on the inner surface of the second tube. The thickness of the wall of the tube 22 is substantially constant, even in the region of the groove. In this case, the latter has a substantially V-shaped section. The connection between the tubes is of the male / female type, the necking 19 being inserted into the flare 16. In this situation, the groove 24 of the second tube is open on the inside of the assembled tubes. The tubes have symmetry of revolution about their common axis A. Similarly, the band of the collar (apart from the region of the legs 12A and 12B which will be described later), as well as the washer, have a symmetry of revolution about the axis A. Generally, the tubes, the collar and the washer, are made of metal. The collar has clamping means. In this case, the band 12 35 of this collar has ends, respectively 12A and 12B, which are substantially radially rectified so as to form support legs. These tabs are pierced so as to allow the passage of the rod of a screw 26 through them. The head 26B of the screw is held with respect to one of the support lugs, in this case the lug 12B, while the thread of the shank of the screw cooperates with a nut 27 which is secured to the lug of the lug. 12A support. Thus, it is by the rotational drive of the head of the screw that the collar is tightened. The rod of the screw has, between the two support lugs, a bead 26C which allows the opening of the band of the collar during unscrewing of the screw, as in WO 2005/057071. Of course, any type of clamping means of the band of the collar can be envisaged, in particular as described in any one of the aforementioned prior patent applications. The clamping system also comprises a washer 28 which has a sealing portion 30 disposed between the facing surfaces of the two tubes. This sealing portion has a generally frustoconical shape, adapted to that of these facing surfaces, which are respectively the outer surface of the necking 19 and the outer surface of the flare 16. These surfaces constitute the sealing surfaces of the tubes, 20 with which the sealing portion 30 of the washer cooperates by its two opposite faces. It is seen, in particular in Figure 7, that the sealing portion has a local annular relief 30A which forms at least one annular projection projecting from one of the faces of said sealing portion. In this case, the relief 30A has two successive annular waves projecting respectively on each of the two faces. Thus, in axial section, the relief 30A has a generally z-shape. When clamping the collar, the relief 30A behaves like a sealing ring, which deforms by crushing its protruding reliefs, to come into intimate contact with the sealing surfaces of the tubes. Referring in particular to Figures 1 and 3 to 7, have seen that the washer 28 comprises an internal cylindrical return 32, which extends axially being connected to the inner edge 30 '(close to the axis A) of the portion sealing 30 of this washer.

In FIGS. 1 and 3, it can be seen that this return 32 covers the groove 24, so that the groove thus covered forms an annular space having a closed axial section, substantially in the form of a triangle. In this case, the cylindrical return 32 extends axially over a length L, greater than the length Lg of the groove and the free end 32A of this return is disposed against the inner periphery 22A of the second tube. In the above, the length Lg of the groove is measured between the two edges of this groove located in the cylindrical envelope of the current internal cylindrical surface of the tube 22A.

As previously indicated, the sealing portion 30 of the washer 28 is generally frustoconical in shape. It can be seen that the cylindrical return 32 forms, in axial section, an acute angle α with this sealing portion. Thus, the return and the sealing portion are in axial overlap with respect to each other. The value of the angle α corresponds to the inclination of the bearing surfaces of the tubes and is generally between 35 and 55, for example of the order of 45. The outer edge 30 "(remote from the axis A) of the sealing portion, which also forms the outer edge of the washer 28 as a whole, is raised relative to the running portion of said portion, which is frustoconical. Thus, this raised edge can promote the correct positioning of the washer 28 relative to the tube 20, the free end of the flare 16 can abut against this raised edge.In this case, this raised edge is substantially perpendicular. to the axis A. FIGS. 8 and 9, which illustrate a variant 25 for the washer of the clamping system according to the invention, are described in these figures, and the same numerical references as in the preceding figures have been retained for The washer 128 is distinguished from the washer 28 of the preceding figures in that it has a set of tabs, which extend from the outer edge 30 "of its sealing portion 30. These tabs are deformed mables and we see them in their initial state, not deformed, in Figure 9, which shows the washer before its introduction into the collar. There are two series of tabs, namely short tabs 34 which, in the undeformed state, are substantially rectilinear, and longer tabs 36, the ends 36A are bent in hooks. The longer legs are fastening lugs which, as can be seen from FIG. 8, are able to cooperate with the band of the collar to retain the washer 128 with respect to this band. It can be seen that the hook ends 36A of the tabs 36 hook onto the edge of one of the collar wings. In this case, the tabs 36 extend from the edge 30 "in a direction substantially opposite to the direction in which the return 32 extends from the edge 30 'These tabs thus cling to that of the wings of the band 12 of the collar which cooperates with the bearing surface 16 of the tube 20. The tabs 36 are deformed when the collar is tightened The tabs 34 which are shorter than the tabs 36 extend from the edge external 30 "in the same direction as the direction in which the return 32 extends from the edge 30 '. For example, they are initially substantially in the extension of the frustoconical portion 15 sealing. In general, in axial section, the direction of a tab 34 is preferably in a range between the axial direction and the extension of the frustoconical portion. As can be understood by considering FIG. 8, the tabs 34 deform when the collar is put in place and then clamped, so as to cooperate with the top of the flare 18 of the tube 22. These tabs serve to centering the washer relative to this tube. They could be as long as the legs 36, but this is not necessary because it is sufficient that their length allows them to come to cap the top of the flare 18. In Figure 8, a tab 34 located in the plane of section is shown in phantom broken in its initial state and solid line in its folded state, due to the fact that it is capped by the collar being tightened. The tabs 34 are preferably in relatively large numbers to enable them to provide effective centering. In practice, their number is advantageously between 10 and 20, for example 15. The tabs 36 may be fewer, as is the case in the example shown. They are, however, advantageously arranged at regular angular intervals. For example, three tabs 36, spaced 120, are provided.

Figures 10 and 11 show another variant for the washer, which also allows its attachment to the collar and its centering on one of the 2906864 9 tubes. In fact, the only difference between this washer 128 'and that of Figures 8 and 9, lies in the direction of the centering tabs 34'. It can be seen that these lugs 34 'this time extend from the edge 30 "of the sealing portion in the same direction as the lugs 36. As a result, as can be seen in FIG. these tabs center the washer on the top of the flare 16 of the tube 20 (which is also its free edge), and no longer on that of the flare 18 of the tube 22. In FIG. 9, the tab 34 located in the cutting plane is shown in its folded state, due to the presence of the collar being clamped, while a tab 36, not located in the cutting plane, is indicated in interrupted broken lines. to the particular shape conferred on it by its frustoconical sealing portion and its cylindrical return, the washer 28, 128 or 128 'can be fitted on the free end of the tube 22 and be carried by this end up to the junction of the two tubes and the installation and tightening of the collar. 128 ', the collar as a whole can even be initially embarked on the tube 20, the band of the collar being retained relative to the washer by the fixing lugs 36.

The presence of the centering tabs of the washers 128 and 128 'ensures proper centering of the washer during clamping of the collar.

Claims (12)

  1. Clamping system for the tight connection of two tubes (20, 22) whose facing ends have bearing surfaces (16, 18) protruding from the cylindrical outer surface of said tubes, the system comprising a collar (10) and a washer (28, 128, 128 '), the collar comprising a band (12) adapted to cooperate with said bearing surfaces by its inner periphery which delimits a recess and means (12A, 12B, 24). for clamping said strip, the washer (28, 128, 128 ') comprising a sealing portion (30) adapted to be disposed between sealing surfaces respectively belonging to each of the two tubes, characterized in that the washer comprises, in addition, an internal cylindrical return (32) which extends axially by being connected to the inner edge (30 ') of said sealing portion (30).   2. System according to claim 1, characterized in that the sealing portion (30) is of generally frustoconical shape and in that the cylindrical return (32) forms, in axial section, an acute angle (a) with said portion sealing. 20   3. System according to claim 1 or 2, characterized in that the washer (28, 128, 128 ') is adapted to be secured to at least one of the elements constituted by the band (12) of the collar and by the one of the tubes (20, 22).   4. System according to any one of claims 1 to 3, characterized in that the washer (128, 128 ') has lugs (34, 34', 36) which extend from the outer edge (30 " ) of the sealing portion (30).   5. System according to claim 4, characterized in that the tabs comprise deformable fastening lugs (36), adapted to cooperate with the band (12) of the collar for retaining said washer relative to this band.   6. System according to claim 5, characterized in that the fastening tabs (36) extend, from the outer edge (30 ") of the sealing portion (30), in a direction substantially opposite to the direction in which extends the internal cylindrical return (32).   A pipe assembly comprising a first and a second tube (20, 22) whose facing ends have bearing surfaces (16, 18) projecting from the cylindrical outer surface of said tubes and a clamping system comprising a collar (10) and a washer (28, 128, 128 '), the bearing surface (16) of the first tube (20) being formed by a flare at the free end of said tube, while the second tube (22) presents, arranged successively towards its free end, a flare (18) forming the bearing surface of the second tube and a necking (19) which, with said flare, forms a groove (24) on the 10 inner surface of the second tube, the washer (28, 128, 128 ') comprising a sealing portion (30) which is disposed between sealing surfaces of the tubes respectively formed by the inner periphery of the flare of the first tube and by the outer periphery of the narrowing of the second tube which is eng disposed in the flare of the first tube, characterized in that the washer (28, 128, 128 ') further comprises an internal cylindrical return (32) which extends axially and is connected to the inner edge (30') said sealing portion (30) and at least substantially covering said groove (24).   8. An assembly according to claim 7, characterized in that the internal cylindrical return (32) extends over a length (L) greater than that (Lg) of the groove (24) and has a free end (32A) arranged against the inner periphery (22A) of the second tube (22).   9. Assembly according to claim 7 or 8, characterized in that the washer (28, 128, 128 ') is secured to at least one of the elements constituted by the band (12) of the collar and by one of the tubes. (20, 22).   10. Assembly according to any one of claims 7 to 9, characterized in that the washer (128, 128 ') has tabs (34, 34', 36) which extend from the outer edge (30 ") the sealing portion (30).   11. Assembly according to claim 10, characterized in that the tabs comprise centering tabs (34, 34 '), which cooperate with the top of the flare (18) of one of the two tubes.   12. Assembly according to any one of claims 10 and 11, characterized in that the washer (128, 128 ') has deformable fixing lugs (36), which cooperate with the band (12) of the collar to retain said washer. compared to this band.