Component of an exhaust system

Abstract

A component of an exhaust system for a combustion engine has a wall in which at least one opening is provided, and a perforated cover which is associated with the opening. A support is provided by which the perforated cover is mounted to the wall of the component. Further, a clearance is provided between the support and the cover such that the cover can shift parallel to the wall of the component.

Claims

1. A component comprising: a wall in which at least one opening is provided, a perforated cover covering said opening, wherein said wall and said perforated cover are made of materials having different thermal expansions, said wall is made of a steel alloy and said perforated cover is made of an alloy resistant to hot-gas corrosion and cold-condensate corrosion, a support to mount said perforated cover to said wall of said component, and a clearance provided between said support and said perforated cover such that said perforated cover is adapted for shifting parallel to said wall of said component, and wherein the component comprises an exhaust component of an exhaust system for a combustion engine.

2. The component of claim 1 wherein the clearance is formed between an end face of said perforated cover and a stop face of said support which is arranged at a distance opposite said end face.

3. The component of claim 2 wherein said support has a mounting portion which is mounted to said wall and a retaining portion for said perforated cover which is offset with respect to said mounting portion as seen in a direction perpendicular to said wall, said stop face being formed by a step at a transition from said mounting portion to said retaining portion.

4. The component of claim 3 wherein said support is a stamped sheet-metal component.

5. The component of claim 3 wherein said mounting portion is welded to said wall.

6. The component of claim 3 wherein said perforated cover is held in a prestressed manner between said mounting portion and said wall.

7. The component of claim 1 wherein at least portions of said support are configured in a double-layered manner.

8. The component of claim 7 wherein said support is a bent sheet-metal component.

9. The component of claim 1 wherein said perforated cover is firmly fastened to said support at a point.

10. The component of claim 1 wherein said support has a wall thickness of less than 1.2 mm.

11. The component of claim 1 wherein said perforated cover has a wall thickness in the order of less than 1.0 mm.

12. The component of claim 1 wherein said support is made of a ferritic steel alloy.

13. The component of claim 1 wherein said support has a wall thickness in the order of 0.8 mm.

14. The component of claim 1 wherein said perforated cover has a wall thickness in the order of less than 0.5 mm.

15. The component of claim 1 wherein said alloy is an austenitic steel alloy or a ferritic alloy.

16. A component of an exhaust system for a combustion engine comprising: a wall in which at least one opening is provided, a perforated cover covering said opening, a support to mount said perforated cover to said wall of said component, wherein said support is a frame which is mounted to said wall and surrounds an outer edge of said perforated cover, and a clearance provided between said support and said perforated cover such that said perforated cover is adapted for shifting parallel to said wall of said component.

17. A component comprising: a wall in which at least one opening is provided, a perforated cover covering said opening, a support to mount said perforated cover to said wall of said component, wherein at least portions of said support are configured in a double-layered manner, wherein said support, as seen in a cross section, has a U-shaped cross-section with two legs, said perforated cover being received between said two legs of said support such that a stop face is formed by an inner face of a bent portion between said two legs, and a clearance provided between said support and said perforated cover such that said perforated cover is adapted for shifting parallel to said wall of said component, and wherein the component comprises an exhaust component of an exhaust system for a combustion engine.

18. The component of claim 17 wherein said two legs are elastically prestressed against each other and against said perforated cover arranged therebetween.

19. The component of claim 17 wherein said support is welded to said wall at the bent portion between said two legs.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described below with reference to two embodiments which are illustrated in the accompanying drawings and which show:

(2) FIG. 1 schematically shows part of an exhaust system having two exhaust-gas-ducting components;

(3) FIG. 2 is a side cross-sectional view of a component with a cover mounted thereto;

(4) FIG. 3 shows the component of FIG. 2 in a perspective exploded view;

(5) FIG. 4 shows the component of FIG. 2 in a perspective top view;

(6) FIG. 5 shows, in an enlarged view, a support with a cover before the mounting to the component;

(7) FIG. 6 is an exploded view of the assembly of FIG. 5;

(8) FIG. 7 shows the component of FIG. 2 in a perspective sectional view;

(9) FIG. 8 is a detail of FIG. 7;

(10) FIG. 9 shows an exhaust-gas-ducting component according to a second embodiment in a sectional view;

(11) FIG. 10 shows part of FIG. 9 in an enlarged view; and

(12) FIG. 11 schematically shows a sheet-metal blank for the support used in the second embodiment.

DETAILED DESCRIPTION

(13) FIG. 1 shows different components of an exhaust system. In this example, a first exhaust pipe 1, a housing 2 and a second exhaust pipe 3 are shown.

(14) The pipes 1 and 3 serve to guide exhaust gas of a combustion engine towards the surroundings. Components that treat the exhaust gas, for example a catalyst substrate or a particle filter, can be arranged in the housing 2. The housing 2 can also be the housing of a muffler.

(15) As far as the components 1, 2, 3 are arranged at a certain distance from exhaust valves of the combustion engine and the temperature of the exhaust gas has therefore already dropped slightly, a ferritic steel alloy can be used as material for the components 1, 2, 3.

(16) In the example embodiment shown, the components 2, 3 are provided with an opening 10. The latter can for example be circular, rectangular, polygonal or oval and have a surface area of some square centimeters. A cover which is fastened to the component by a support is respectively associated with the opening 10. This is explained in detail below.

(17) FIGS. 2 to 8 show a first embodiment. In this embodiment, a perforated cover 12 is used which, generally speaking, is fixed against the wall of the component 3 by a support 14.

(18) Though the example embodiment of the first embodiment relates to a cover 12 which closes an opening 10 in an exhaust-gas-ducting pipe, it has to be understood that the opening 10 can also be provided in a different place of the exhaust system. The opening 10 can be provided in the envelope surface of the housing of the component 2, as shown in FIG. 1, or also in one of the end walls of the component 2.

(19) The perforated cover 12 is made of a metal foil, or of a metal sheet, the wall thickness of which may for example be 0.3 mm. It is provided with a plurality of small perforations, the part of the perforations in the total area of the cover being in the range from 1 to 10% and preferably from 1 to 3%.

(20) The perforations may have a circular shape, a rectangular shape or a different geometry. When the open area thereof is converted into a circular shape, it corresponds to the diameter of the opening in the order of 1 mm to 1.5 mm.

(21) When the dimensions of the openings are smaller than these values, this is also referred to as microperforated cover.

(22) An alloy which is resistant against hot-gas corrosion and cold-condensate corrosion, such as Inconel, is used as material for the cover 12. Preferably, an austenitic steel alloy or an appropriate ferritic alloy can be used.

(23) The wall thickness of the cover is below 1 mm and in particular in the order of 0.5 mm.

(24) These values apply for the initial metal sheet. With regard to cutting or reshaping fabrication methods as can be used for the manufacture of the cover, the cover may possibly be thicker after processing, as far as the distance of the surface points is measured, since burs can occur.

(25) The support 14 is configured like a frame and is made of sheet metal. A ferritic steel alloy is preferably used as material, preferably a steel alloy having the same thermal expansion behavior as the component or the wall of the component to which it is connected.

(26) The support 14 has a peripheral mounting portion 16 which is intended to be adapted to the wall of the component 3. A retaining portion 18 is provided within the peripheral mounting portion 16. The retaining portion 18 forms the inner edge of the support 14 and defines a recess which is slightly larger than the opening 10.

(27) As is in particularly visible in FIG. 8, the retaining portion 18 is offset with respect to the mounting portion in a direction perpendicular to the mounting portion 16 and thus also perpendicular to the wall of the component 3. The offset corresponds at least to the thickness of the perforated cover 12. The offset is preferably slightly larger (cf. in particular FIG. 2).

(28) The offset between the retaining portion 18 and the mounting portion 16 can be obtained in that a plane sheet metal blank of the support is stamped appropriately.

(29) The retaining portion 18 defines an accommodation for the cover 12 which can be arranged in this accommodation (cf. in particular FIGS. 3, 5 and 6). The dimensions of the cover 12 are chosen such that the cover is slightly smaller than the accommodation. In other words, a small clearance s remains between the end faces of the cover 12 and a step 20 formed at the transition between the retaining portion 18 and the mounting portion 16. This clearance s is in the range of 0.2 to 4 mm.

(30) When the support 14 is mounted to the component 3, the perforated cover 12, due to the clearance s (FIG. 8), can wander below the retaining portion 18 parallel to the wall of the component 3, more specifically until it respectively abuts against the step 20 which acts as stop face on the support for the cover 12.

(31) The support 14 is firmly fastened to the wall of the component 3 by its mounting portion 16. In the example embodiment shown, the mounting portion 16 is welded using several spot-welding points 22 (cf. FIG. 4). It is also possible to use a weld seam 24 extending outside around the mounting portion 16 (cf. FIG. 2).

(32) The support 14 can be mounted to the component 3 in a pre-bent state (cf. FIG. 3) or alternatively also be placed thereon in the plane state (cf. FIG. 5) and then be pressed against the component 3 to follow the contour of the component 3. It is then welded thereto.

(33) As can be seen in FIG. 8, a fixing point 26 is provided at which the cover 12 is fixed to the retaining portion 18. A spot-welding point can be involved here. The fixing point 26 determines the position of the perforated cover 12 relative to the support 14 at this point, such that the cover 12 expands or contracts starting from this point when temperature changes act. A pre-mounted assembly is furthermore formed in this way.

(34) The cover 12 is received in an elastically resilient manner between the outer face of the wall of the component 3 and the face of the retaining portion 18 turned towards the component 3. To this end, the cover can be pre-bent or a bead can be stamped along the outer edge of the cover. By way of alternative, as can be seen in FIG. 2, an outer edge 28 of the cover 12 can be folded so that the cover 12 is configured in a double-layered manner in the region of its outer edge. Due to the returning forces of the folded edge portion, the desired resilient prestress is generated here.

(35) On the one hand, the spring prestress is so high that undesired vibration noises due to a movement of the cover 12 relative to the component 3 and the support 14 are avoided. On the other hand, the spring forces are so low that a temperature-related relative movement of the cover 12 with respect to the component 3 and the support 14 is permitted without excessively high mechanical loads acting onto the cover 12.

(36) FIGS. 9 to 11 show a second embodiment. The same reference numbers are used for the components known from the first embodiment, and in this respect, reference is made to the explanations above.

(37) The difference between the first and the second embodiments is that in the second embodiment 14, the support 14 is realized in a double-layered manner. As seen in cross-section perpendicular to an outer edge of the support 14, it has a U-shaped cross-section (cf. FIG. 10), the cover 12 being arranged between the two opposite inner faces of the two legs 14B, 14B. The inner side of the bending point between the two legs 14A, 14b here acts as stop face 20.

(38) The support 14 may be made of a sheet metal blank 14 as shown in FIG. 11.

(39) In the same manner as in the first embodiment, the cover 12 in the second embodiment is slightly smaller than the accommodation formed within the support 14 such that a clearance s remains between the front faces of the cover 12 and the stop face 20.

(40) In the second embodiment, an elastic prestress also acts between a cover 12 and the support 14. Here, the latter can be generated in that the two legs 14A, 14B of the support 14 receive the cover 12 therebetween like a spring clamp. In addition, or by way of alternative, it can be provided that the outer edge of the cover 12 is folded as known from the first embodiment.

(41) The support 14 along with the cover 12 can form a pre-mounted assembly which is mounted to the component 3. To this end, a weld seam 24 can be used which connects the support 14 to the wall of the component 3 in the region of the bending point between the two legs 14A, 14B. The weld seam 24 can be provided in a surrounding manner or merely in sections.

(42) By way of alternative, it is also possible to first weld the sheet metal blank 14 of the support 14 to the component 3, for example by several spot welds 22, then to place the cover 12 thereon and then to fold the outer tabs such that the support 14 is double-layered.

(43) A fastening of the cover 12 with respect to the support 14 at a fixed point, in particular by a spot-welding point can also be provided in the second embodiment.

(44) Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the true scope and content of this disclosure.