Title of Invention

ASSEMBLY WITH A PLURALITY OF AIR-GAP-INSULATED EXHAUST TUBES AND ONE CONNECTING TUBE AND METHOD FOR MANUFACTURING A CONNECTING END OF AN AIR-GAP-INSULATED EXHAUST TUBE

Abstract

This invention relates to an assembly in particular for an exhaust system, comprising at least two double-sheeted gas-carrying tubes (5), which each include an outer tube (10) and an inner tube (12), and a connecting tube (7) which is gas-tightly connected with the outer tubes (10), so that a transition is created from the two gas-carrying tubes (5) to the connecting tube (7), wherein at their end associated to the connecting tube (7) the outer tubes (10) each include a connecting edge (14) which is connected with the connecting edge (14) of the adjacent gas-carrying tube (5), characterized in that the connecting edge (14) is integrally formed with the outer tube (10) and is obtained by plastic deformation of the outer tube (10). This invention also relates to a method for manufacturing a connecting end of a double-sheeted gas-carrying tube (5) formed of an outer tube (10) and an inner tube (12), characterized in that a connecting end of the outer tube (10), to which a connecting tube (7) will be attached, is plastically deformed by means of a punch (26).

Full Text

PCT/EP2006/007620 Assembly with a plurality of air-gap-insulated exhaust tubes and one connecting tube and method for manufacturing a connecting end of an'air-gap- insulated exhaust tube This invention relates to an assembly, in particular for an exhaust system, comprising at least two double-sheeted gas-carrying tubes, which each include an outer tube and an inner tube, and one connecting tube which is gas-tightly connected with the outer tubes, so that a transition is created from the two gas- carrying tubes to the connecting tube, wherein at their end associated to the connecting tube the outer tubes each have a connecting edge which is connected with the connecting edge of the adjacent gas-carrying tube. This invention also relates to a method for manufacturing a connecting end of a double-sheeted gas- carrying tube formed of an outer tube and an inner tube. Such gas-carrying tube also is known as an air-gap-insulated exhaust tube. The double-sheeted construction involves some problems when two or more gas- carrying tubes, for instance on the side of the exhaust manifold, must be connected to a single connecting tube. Since all tubes usually have a circular cross-section, the problem is to connect two circular tubes to one single circular tube. In the prior art, this problem has previously been solved such that the ends of the gas-carrying tubes associated to the connecting tube were cut off, and special connecting pieces were welded thereto. It was generally assumed that a cross-sectional shape suitable for a gas-tight connection with the connecting tube cannot be obtained in some other way. The connecting piece to be attached was manufactured separate from the outer tube and has had a circular cross-section at the end associated to the gas-carrying tube, so that it can be welded thereto, and a D-shaped cross-section at its opposite end. This allows to arrange the two gas-carrying tubes adjacent each other such that the two D-shaped cross- sections are lying back to back. The straight edges of the connecting pieces then form a connecting edge which can be welded to the adjacent connecting edge. On the whole, the two connecting pieces together form a cross-section which resembles the shape of an oblong hole. With its end facing the gas-carrying tubes, the connecting tube will be configured with the same cross-section, so that -2- the connecting tube can be put onto the two gas-carrying tubes and be welded thereto. What is disadvantageous in this kind of connection is the high effort required to provide an end at the gas-carrying tubes which is suitable for gas-tight connection with the connecting tube. The object of the invention consists in creating an assembly as mentioned above and a method for manufacturing a connecting end of a double-sheeted gas-carrying tube, which is characterized by lower costs. This object is achieved with an assembly mentioned above, by forming the connecting edge integrally with the outer tube and by obtaining it by plastic deformation of the outer tube. In a method as mentioned above it is provided in accordance with the invention that a connecting end of the outer tube, to which a connecting tube will be attached, is plastically deformed by means of a punch. The invention is based on the basic idea to no longer provide the suitable cross-sectional shape on a separate component and connect the same with the outer tube of the corresponding gas-carrying tube, as is done in the prior art, but to directly bring the outer tube itself into the desired shape. For this puFpose, a punch is used, which is pressed into the connecting end of the outer tube facing the connecting tube. The outer tube thereby is deformed such that the connecting edge is obtained, which can then be connected with the adjacent connecting edge of the further gas-carrying tube. When two gas-carrying tubes must be accommodated in the connecting tube, the connecting end of the two outer tubes of the gas-carrying tubes each preferably has a D-shaped cross-section. But when three gas-carrying tubes must be accommodated in the connecting tube, the connecting ends of the outer tubes preferably have a sector-shaped cross-section. Other cross-sectional shapes at the connecting end of the outer tube are of course also conceivable. It is only important that between the adjacent outer tubes no gap or at least no large gap is formed, so that the outer tubes can gas-tightly be connected with each other inside the connecting tube, for instance by a welding seam. When the connecting end of the outer tube of the gas-carrying tube is plastically deformed after the inner tube has been attached, a hollow punch is -3- used, which includes a recess for the inner tube. In this way, the inner tube does not impair the plastic deformation of the outer tube. Depending on the requirements, the outer tube can be deformed to its final cross-section in a single embossing step, or several embossing steps can be used, which via several intermediate stages bring the end of the outer tube associated to the connecting tube into its final shape. A one-step forming method is characterized by particularly low costs. A multi-step forming method leads to a reduced axial compression of the outer tube. The invention will subsequently be described with reference to various embodiments which are illustrated in the attached drawings, in which: - Figure 1 shows an assembly of the invention in a schematic top view; - Figure 2 schematically shows a section along plane ll-ll of Figure 1; - Figure 3 schematically shows the forming of the end of an outer tube associated to a connecting tube; - Figures 4a to 4c show various cross-sectional shapes of the end of a gas- carrying tube associated to a connecting tube in a two-step forming method; and - Figure 5 shows three gas-carrying tubes accommodated in one connecting tube in a view corresponding to that of Figure 2. Figure 1 shows two gas-carrying tubes 5 which are connected to a connecting tube 7. The two gas-carrying tubes 5 each include an outer tube 10 and an inner tube 12. The gas-carrying tubes in particular serve to carry exhaust gas of an internal combustion engine and also are referred to as air-gap-insulated exhaust tubes. The connecting tube 7 is of the single-sheeted type. The connecting tube also can be of the double- or multi-sheeted type. Connecting tube here is also meant to be a further exhaust-gas-carrying component, for instance the inlet or outlet funnel of a catalyst, a Diesel particulate filter, etc.. For better clarity, the walls of the various tubes are symbolized by a single line in all drawings, and between adjacent walls a space is shown, in order to better differentiate the individual components. The spacers disposed between the outer tube and the inner tube are not shown either. -4- For connection with the connecting tube, the two gas-carrying tubes 5 each include particularly shaped connecting ends 9, which are put into the connecting tube 7 adjacent to each other. As shown in Figure 2, at its end facing the gas-carrying tubes 5 the connecting tube 7 has a cross-section which resembles an oblong hole. At their connecting end facing the connecting tube 7, the outer tubes 10 of the gas- carrying tubes 5 each have a D-shaped cross-section. The two cross-sections are arranged such that they lie back to back. Thus, the two straight, vertical portions of the "D" rest against each other. The corresponding edges can be referred to as connecting edges, as they are welded to each other. The welding seam is indicated with the reference numeral 16. Away from the welding seam 16, a further welding seam 17 extends in axial direction, which constitutes a fillet weld between the two outer tubes 10. The same extends approximately to the end of the connecting tube 7. The end of the connecting tube 7 is welded to the outer tubes 10 by a circumferential welding seam 18. In this way, a generally gas- tight connection is ensured between the gas-carrying tubes 5 and the connecting tube 7. With reference to Figures 3 and 4 it will now be explained how the cross- sectional shape of the connecting end of each gas-carrying tube 5 accommodated in the connecting tube 7 is obtained. The gas-carrying tube is inserted in a tool 20, which consists of an upper part 22 and a lower part 24. The tool is designed such that it reliably clamps the outer tube 10. In the vicinity of the connecting end of the outer tube 10 to be accommodated in the connecting tube 7, the tool 20 includes a recess whose shape corresponds to the cross-section of the connecting end. In this region, a punch 26 is pressed into the outer tube 10, so that the same is expanded and deformed plastically. The punch 26 is a hollow punch with a recess 28 for the inner tube 12. At its front edge, the punch 26 is provided with two insertion edges 29, 30 which facilitate insertion between the inner tube 12 and the outer tube 10. Forming the end of the outer tube 10 associated to the connecting tube can be effected in a single step or, as shown in Figures 4a to 4c, in several steps. Figure 4a shows the outer tube 10 with the inner tube 12 disposed therein, wherein the outer tube 10 is in the starting condition. Figure 4b shows the gas- -5- carrying tube 5 with the outer tube 10 formed into an intermediate condition. The cross-sectional shape of the outer tube approaches a "D". Figure 4c shows the gas-carrying tube with completely formed outer tube 10. The connecting edge 14 has been formed, which is welded to the connecting edge 14 of the second gas- carrying tube 5. Figure 5 schematically shows an example of how three gas-carrying tubes can be connected with one connecting tube. The ends of the respective outer tubes 10 associated to the connecting tube 7 are formed such that they have a sector-shaped cross-section. With a suitable configuration of the connecting ends of the gas-carrying tubes it is also possible to connect more than three gas- carrying tubes with one connecting tube. -6- List of Reference Numerals 5 gas-carrying tube 7 connecting tube 9 connecting end 10 outer tube 12 inner tube 14 connecting edge 16 welding seam 17 welding seam 18 welding seam 20 tool 22 upper part 24 lower part 26 punch 28 recess 29 insertion edge 30 insertion edge Claims 1. An assembly, in particular for an exhaust system, comprising at least two double-sheeted gas-carrying tubes (5), which each include an outer tube (10) and an inner tube (12), and one connecting tube (7) which is gas-tightly connected with the outer tubes (10), so that a transition is created from the two gas-carrying tubes (5) to the connecting tubes (7), wherein at their end associated to the connecting tube (7) the outer tubes (10) each include a connecting edge (14) which is connected with the connecting edge (14) of the adjacent gas-carrying tube (5), characterized in that the connecting edge (14) is integrally formed with the outer tube (10) and is obtained by plastic deformation of the outer tube (10). 2. The assembly according to claim 1, characterized in that two gas- carrying tubes (5) are accommodated in the connecting tube (7) and the ends of the outer tubes (10) associated to the connecting tube (7) have a D-shaped cross-section. 3. The assembly according to claim 1, characterized in that three or more gas-carrying tubes (5) are accommodated in the connecting tube (7) and that the ends of the outer tubes (10) facing the connecting tube (7) have a sector-shaped cross-section. 4. The assembly according to claim 1, characterized in that between the outer tube (10) and the inner tube (12) an air gap is provided. 5. A method for manufacturing a connecting end of a double-sheeted gas- carrying tube (5) formed of an outer tube (10) and an inner tube (12), characterized in that a connecting end of the outer tube (10), to which a connecting tube (7) will be attached, is plastically deformed by means of a punch (26). 6. The method according to claim 5, characterized in that the inner tube (12) is mounted in the outer tube (10), after the connecting end has been plastically deformed. 7. The method according to claim 5, characterized in that the inner tube (12) is mounted in the outer tube (10), before the connecting end has been plastically deformed. -8- 8. The method according to claim 7, characterized in that a hollow punch (26) is used, which includes a recess (28) for the inner tube (12). 9. The method according to any of claims 5 to 8, characterized in that the connecting end is deformed into its final shape in a single embossing step. 10. The method according to any of claims 5 to 8, characterized in that the connecting end is deformed into its final shape in several embossing steps. 11. The method according to any of claims 5 to 10, characterized in that the outer tube (10) and the inner tube (12) are trimmed before deforming the outer tube (10). 12. The method according to any of claims 5 to 10, characterized in that the outer tube (10) and the inner tube (12) are trimmed after deforming the outer tube (10). This invention relates to an assembly in particular for an exhaust system, comprising at least two double-sheeted gas-carrying tubes (5), which each include an outer tube (10) and an inner tube (12), and a connecting tube (7) which is gas-tightly connected with the outer tubes (10), so that a transition is created from the two gas-carrying tubes (5) to the connecting tube (7), wherein at their end associated to the connecting tube (7) the outer tubes (10) each include a connecting edge (14) which is connected with the connecting edge (14) of the adjacent gas-carrying tube (5), characterized in that the connecting edge (14) is integrally formed with the outer tube (10) and is obtained by plastic deformation of the outer tube (10). This invention also relates to a method for manufacturing a connecting end of a double-sheeted gas-carrying tube (5) formed of an outer tube (10) and an inner tube (12), characterized in that a connecting end of the outer tube (10), to which a connecting tube (7) will be attached, is plastically deformed by means of a punch (26).

Documents:

01150-kolnp-2008-abstract.pdf

01150-kolnp-2008-claims.pdf

01150-kolnp-2008-correspondence others.pdf

01150-kolnp-2008-description complete.pdf

01150-kolnp-2008-drawings.pdf

01150-kolnp-2008-form 1.pdf

01150-kolnp-2008-form 2.pdf

01150-kolnp-2008-form 3.pdf

01150-kolnp-2008-form 5.pdf

01150-kolnp-2008-international publication.pdf

01150-kolnp-2008-international search report.pdf

01150-kolnp-2008-pct priority document notification.pdf

01150-kolnp-2008-pct request form.pdf

1150-KOLNP-2008-(06-11-2012)-CORRESPONDENCE.pdf

1150-KOLNP-2008-(20-08-2014)-ABSTRACT.pdf

1150-KOLNP-2008-(20-08-2014)-ANNEXURE TO FORM 3.pdf

1150-KOLNP-2008-(20-08-2014)-CLAIMS.pdf

1150-KOLNP-2008-(20-08-2014)-DRAWINGS.pdf

1150-KOLNP-2008-(20-08-2014)-EXAMINATION REPORT REPLY RECIEVED.PDF

1150-KOLNP-2008-(20-08-2014)-FORM-1.pdf

1150-KOLNP-2008-(20-08-2014)-FORM-2.pdf

1150-KOLNP-2008-(20-08-2014)-PETITION UNDER RULE 137.pdf

1150-KOLNP-2008-CORRESPONDENCE 1.2.pdf

1150-KOLNP-2008-CORRESPONDENCE OTHERS 1.1.pdf

1150-KOLNP-2008-CORRESPONDENCE-1.2.pdf

1150-kolnp-2008-form 18.pdf

1150-KOLNP-2008-FORM 26.pdf

1150-KOLNP-2008-INTERNATIONAL EXM REPORT.pdf

1150-KOLNP-2008-INTERNATIONAL SEARCH REPORT 1.1.pdf

1150-KOLNP-2008-OTHERS.pdf

1150-KOLNP-2008-TRANSLATED COPY OF PRIORITY DOCUMENT.pdf

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