EP2176527A1

EP2176527A1 - Exhaust gas treatment device for an exhaust gas system and method for the production of an exhaust gas treatment device

Info

Publication number: EP2176527A1
Application number: EP08773956A
Authority: EP
Inventors: Wolfgang Hahnl; Stefan Hackenberg; Christoph Hossfeld
Original assignee: Emcon Technologies Germany Augsburg GmbH
Current assignee: Faurecia Emissions Control Technologies Germany GmbH
Priority date: 2007-07-16
Filing date: 2008-07-10
Publication date: 2010-04-21
Also published as: DE102007032982A1; US20110247310A1; WO2009010229A1; CN101743387A; KR20100041837A; DE102007032982B4

Abstract

At least one hollow body (18) being configured to be gas permeable is disposed in an exhaust gas treatment device for an exhaust gas system, having a housing (12) comprising an inlet (14) and an outlet (16), in the flow direction from the inlet (14) to the outlet (16). The hollow body (18) is configured of at least one base element made of a porous substrate, wherein each base element has at least two connecting regions, and two connection regions of one or more base elements overlap in the region of the connection to form the hollow body (18). The connecting regions to be connected are pressed together in order to form the hollow body (18).

Description

Exhaust gas treatment device for an exhaust gas system and method for producing an exhaust gas treatment device

The invention relates to an exhaust gas treatment device for an exhaust system, in particular for an internal combustion engine, e.g. of a vehicle. There are known particulate filters for diesel exhaust, in which the particulate

Exhaust gases flow through a hollow body of a porous substrate whose pore size is selected so that the soot particles are deposited on the porous substrate. A preferred substrate for producing these hollow bodies are sheets of metal foam. When assembling the plates to the hollow body, it is important that no gas leaks between the individual segments caused by the particle-laden exhaust gas can flow through unfiltered, as this would run counter to the purpose of the filter.

The object of the invention is to provide an exhaust gas treatment device in which gaps between the plate edges of a porous substrate can be avoided in a simple way.

For this purpose, in an exhaust gas treatment device for an exhaust system, which has a housing which has an inlet and an outlet, and at least one gas-permeable hollow body, which is arranged in the flow path from the entrance to the exit and in which the hollow body of at least one basic element of a porous Substrate is formed, wherein each base member has at least two connecting portions, provided that each overlap two connection areas of one or different basic elements in the region of a compound to form the hollow body. The overlapping of the connecting regions of adjacent sections of the basic elements ensures that no leakage occurs, through which the exhaust gas can pass unfiltered through the hollow body. Since only the blank sizes of the individual basic elements must be chosen to be correspondingly large, this design ensures leak-free in a simple manner. In this case, connecting regions of a single (bent) basic element as well as connecting regions of adjacent, separate basic elements can be connected. As a porous substrate, for example, a metal foam, a metal sponge, a metallic hollow sphere structure or generally a porous metal may be used. In such materials, the metal forms a lattice or cell structure having a pore size of the micrometer range to a few millimeters, with typically 80% or more of the material being formed by voids. Such metal foams, for example, by foaming a molten metal, sintering of suitable metal powders or heating with suitable. Generated blowing agents provided metal powders. Metal sponges can be produced, for example, on the basis of metal powders-treated precursor foams made of plastic in a sintering process.

Alternatively, nonwoven mats, e.g. made of fibers of a ceramic material or silicon carbide, suitable as a porous substrate.

In order to establish the connection between the individual connection regions, the connection regions are preferably pressed together and through the

Intermeshing surface structures of the substrate, e.g. the edges of open pores or loose fiber sections in the region of the surface, connected to each other. The porous substrate in both connecting regions acts as a kind of hook-and-loop fastener when two connecting regions are placed flat on one another and pressed against one another. The surface structures of one connection area penetrate into the surface of the other one

Connection area and the surface structures interlock with each other. In this way, a flat connection is formed along the entire overlap of the two connection areas, which ensures that there are no gaps through which exhaust gas can pass unfiltered through the connection.

It is possible to use the connection areas exclusively through the

Intermeshing of the surface structures of the one or more basic elements to each other by exploiting only the Velcro effect of the substrate is exploited. The attachment effect can be especially on the surface of the

Set overlap area.

Alternatively, however, the connection areas can also be fixed to one another by means of staples or stitching or another suitable fastening. In In this case, the leakage is still achieved by the overlapping and interlocking of the connection areas. However, the fixation of the connection areas to each other is supported by further measures, so that the connection areas can not be separated during operation.

It is possible to produce the hollow body from a plurality of basic elements, which are connected to one another in adjacent connecting regions by compression.

The total length of the base elements is preferably selected to be longer than the circumference of the hollow body, and the base elements are helically rolled up, so that the hollow body has a multilayer wall.

The individual basic elements may have a different gas permeability, density and / or porosity. They also do not have to be the same length. The connection areas can be at the edges of the or

Basic elements may be formed as well as on the surface of a base element. The latter is advantageous if the hollow body has a spiral-like, multi-layered wall. In this case, a connection area located at the edge is preferably pressed with a connection area lying on the surface for closing the hollow body.

In a preferred embodiment, the hollow body has a base element or a group of basic elements bent into a cone or a truncated cone. In this case, a flat blank is rolled up into a cone or truncated cone. For closing, for example, the connection areas of the same basic element are connected to each other. Another way to close the hollow body is to connect a peripheral connection area with a connection area on the surface of the already formed hollow body.

It is possible, for example, to manufacture two such hollow bodies and, conversely, to insert the cones or the truncated cones into one another in order to provide the largest possible gas-flow area in the housing. - A -

When the base member has a thickness of about 1 to 10 mm, and more preferably from 1 to 3 mm, the substrate plate can be wound well into a hollow body despite the brittleness of the material.

With such a thickness also the pressing for fixing the connection areas to each other works very well.

The same technique that is used to connect the basic elements with each other, can also be used to attach the entire hollow body in the

Housing be used. In particular, the hollow body can be at a in the

Housing arranged frame by an interaction of the structure of the metal foam and the surface of the frame.

The invention further relates to a method for producing an exhaust gas treatment device, in particular having the abovementioned features, comprising the following steps:

Providing a primitive or group of primitives from a porous substrate, each primitive comprising at least two

Has connection areas,

Superimposing two connection areas of one or more basic elements to be connected, and

- Pressing the connection areas to be joined together to form the hollow body.

During pressing, the edges of the substrate in each case two connection areas can interlock with each other.

Preferably, the pressing takes place while the resulting hollow body is bent into its desired shape. As already explained in more detail above, this procedure represents a quick, simple and inexpensive way of forming the hollow body of an exhaust gas purification device.

The basic element for the group of basic elements is in this case for example cut in the form of a rolled-off conical surface or truncated cone surface and the blank to a cone or Rolled up truncated cone, wherein the connecting portions of the blank overlap. These overlapping connection areas are pressed together.

Further features and advantages of the invention will become apparent from the following description of an embodiment in conjunction with the accompanying drawings. In these show:

- Figure 1 is a schematic sectional view of an inventive

Exhaust treatment device;

FIG. 2 shows a blank form for a basic element of an exhaust gas treatment device according to the invention;

- Figure 3 is a schematic sectional view through a hollow body of an exhaust gas treatment device according to the invention according to a first variant;

- Figure 4 shows a schematic section through a hollow body of an exhaust gas treatment device according to the invention according to a second

Variant;

- Figure 5 is a schematic plan view of a hollow body of an exhaust gas treatment device according to the invention;

FIG. 6 shows a schematic view of a basic element; FIG. 7 shows schematically a basic element with different variants of a

Connection group; and

FIG. 8 is a schematic view of a multilayered wall section of FIG

Hollow body in Figure 3.

The exhaust treatment device 10 for an exhaust system shown in Figure 1, e.g. That of a diesel engine, has a housing 12 with an input 14 and an output 16. The housing 12 is formed by a rigid metal body. The exhaust treatment device 10 is located in

Exhaust gas stream, which is illustrated by the arrows in Figure 1. Two gas permeable

Hollow body 18 are arranged in the flow path from the input 14 to the output 16, that the exhaust gas in any case at least one wall of the Hollow body 18 must flow to pass through the exhaust treatment device 10.

The exhaust treatment device 10 is e.g. a particulate filter in which soot particles are filtered out of the exhaust gas. Each of the hollow bodies 18 is composed of one or more basic elements 20,

20 ', 20 "with a blank made of a porous substrate, here formed from a metal foam plate The term" metal foam "has become common in the general usage of the art for all types of porous metals, regardless of whether they physically physically true with foams a cellular structure with open or closed pores or whether the material is more likely to have a sponge structure with a grid of webs. Even structures of sintered microspheres are referred to in this sense as "metal foam." In the present example, the metal foam sheets are plates of a metal sponge, but other types of "metal foams" could also be used.

The metal foam sheets have a thickness of 1 to 10 mm, and preferably from 1 to 3 mm.

In the embodiment shown in Figure 2, the base member 20 has the form of a rolled-off truncated cone surface, which can be rolled up into a truncated cone. The opening angle of the blank comprises, for example, 30-45 °. The entire straight sides of the base element 20 each form a connection region 22, which extends over a few centimeters into the surface of the base element 20. In this state, the subdivision is of a purely conceptual nature, the substrate in the connection regions 22 does not differ in its composition from the rest of the substrate of the base element 20.

Figure 7 shows different variants for the formation of a lying at the edge of the primitive connection area, shown in different dashed lines. In the illustrated, designed as a truncated cone base element 20 of the connecting portion 22, for example in the region of the longer base side (dashed) and the shorter Grundεeitε (dotted) extended or bulged in the middle of the straight side (with the two shown by dotted lines). Each of these designs ensures that the connection line does not coincide with the bending line and causes in places a greater overlap with the respective edge region to be joined. This counteracts bulging of the hollow body 18 in the exhaust gas flow.

The substrate of the base member 20 is sectioned with a coating 23, e.g. as a so-called washcoat, provided with a catalyst material, is provided. The coating 23 leaves free the edge regions of the base element 20, in particular the connecting regions 22 and the regions 29, which later serve at the ends 27 of the hollow body 18 for fastening in the housing 12. Especially the areas 29 play no role in the exhaust gas purification, so that can be dispensed with the application of catalyst material at these locations. It is also possible to coat only one, some or all of the connection regions 22. The base member 20 is then rolled up into a truncated cone so that the connecting portions 22 overlap, as shown in FIG. After or during the superimposition, the overlapping connection regions 22 are pressed together along their entire length and width, wherein the surface structures, in this case the webs at the pore edges of the connection regions 22, penetrate into the respective other connection region 22 and there in the manner of a hook and loop fastener with the surface structures of the other connecting portion 22 hooked. This connection of the surface structures occurs over the entire area of the connecting regions 22, so that no openings or gaps remain, which would constitute a leak for a particle-laden exhaust gas stream.

Of course, two or more basic elements 20, 20 ', 20 "may also be assembled to form a hollow body 18. These may be in the form of flat or slightly curved plates, for example To achieve the design according to the invention.

It is possible to line up a plurality of basic elements 20, 20 ', 20 ", so that a group of basic elements is formed wound so that it receives a spiral-like, multi-layered wall, in which several substrate layers lie on each other (Figures 3 and 8). The individual connection regions 22 preferably lie one above the other at one point, but could also be arranged offset relative to one another along the circumference of the hollow body 18 (see FIG. 8).

The basic elements 20, 20 ', 20 "can have different porosities, so that the individual layers unfold different filtering action in the wall of the hollow body 18. However, the porosity can also be chosen to be the same for all basic elements 20, 20', 20". The individual base elements 20, 20 ', 20 "may optionally be coated or uncoated, whereby a section-wise coating, as described above, is also possible.

The last connecting region 22 of the outermost base element 20 "is pressed together with another connecting region 22 of the same or a following basic element, that the outer circumference of the hollow body 18 has no gap or step, and the inside of the hollow body 18 is also without gap or step (FIG. thus only with the natural roughness of the substrate).

It is possible to additionally secure the connected connection regions 22 by a further attachment 26, e.g. may be formed by staples or seams. For the seam, a metal wire is preferably used. This is shown in FIGS. 4 and 5.

For the exhaust gas treatment device 10 in FIG. 1, a second hollow body 18 is now produced. For this purpose, a second basic element 20 or a second group of basic elements 20, 20 ', 20 "are cut, this time in the form of a rolled-up conical surface, which is rolled up into a cone, wherein in turn the connecting regions 22 are overlapped on the straight edges and pressed together Then, the cone is inserted into the truncated cone as shown in Figure 1, and the hollow bodies 18 are fixed in the housing 12.

For attachment, the two ends 27 of the cone or of the truncated cone are fastened to a frame 24 arranged in the housing 12. Of the Frame 24 is preferably made of a sturdy sheet metal. The attachment of the hollow body 18 on the frame 24 can be done in any suitable manner. One possibility is to design the surface of the frame 24, for example, by providing a correspondingly rough surface, that the rough metal foam of the hollow body 18 can hook on it analogously to the connection of the connecting portions 22 of the base elements 20.

Before or during attachment to the housing 12, the hollow bodies 18 are calibrated to the exact dimensions of the attachment to the frame 24.

Of course, instead of a truncated cone, other suitable shapes, e.g. a cylinder, are manufactured with the inventive technique. In particular, the outer hollow body 18 in Figure 1 could be a cylinder.

Claims

claims

Exhaust gas treatment device for an exhaust system, comprising a housing (12) having an inlet (14) and an outlet (16), and at least one gas permeable hollow body (18) formed in the

Flow path from the input (14) to the output (16) is arranged and which is formed of at least one base member (20, 20 ', 20 ") of a porous substrate, wherein each base member (20, 20', 20") at least two connecting portions (22) and in each case two connecting regions (22) of one or more

Base elements (20, 20 ', 20 ") overlap in the region of a connection to form the hollow body (18).

2. exhaust treatment device according to claim 1, characterized in that the connecting regions (22) are pressed and are connected to each other by the intermeshing of surface structures of the porous substrate of the respective connecting portions (22).

3. exhaust treatment device according to one of the preceding claims, characterized in that the porous substrate is a metal foam, a metal sponge, a hollow sphere structure or a fiber mat.

4. exhaust treatment device according to one of the preceding

Claims, characterized in that the hollow body has a spiral-like, multi-layered wall.

5. exhaust gas treatment apparatus according to any one of claims 2 to 4, characterized in that the connecting portions (22) exclusively by the interlocking of the surface structures of the porous substrate of the / of the base element (s) (20, 20 ', 20 ") are fixed to each other.

6. exhaust treatment device according to one of claims 2 to 4, characterized in that the connecting portions (22) are fixed by stapling or sewing together.

7. exhaust treatment device according to one of the preceding claims, characterized in that the hollow body (18) has a bent to a cylinder, cone or truncated cone basic element (20) or group of basic elements (20, 20 ', 20 ").

8. exhaust treatment device according to one of the preceding

Claims, characterized in that the base element (20, 20 ', 20 ") has a thickness of about 1-10 mm.

9. exhaust treatment device according to one of the preceding claims, characterized in that the hollow body (18) on a housing (12) arranged frame (24) by an interaction of the structure of the porous substrate and the surface of the frame (24) is fixed.

10. A method for producing an exhaust gas treatment device according to one of the preceding claims, comprising the following steps:

- Providing at least one basic element (20, 20 ', 20 ") of a porous substrate, wherein each base member (20, 20', 20") at least two

Has connecting regions (22),

- Overlay two connecting portions (22) of one or more basic elements (20, 20 ', 20 ") to be connected, and

- Pressing the connecting portions (22) to be joined together to form the hollow body (18).

11. The method according to claim 10, characterized in that interlock with each other during pressing surface structures of the porous substrate in each case two connecting regions (22).

12. The method according to any one of claims 10 and 11, characterized in that the connecting regions (22) are fixed by stapling or sewing together.

13. The method according to any one of claims 10 to 12, characterized in that a base element (20, 20 ', 20 ") or a group of basic elements (20) is cut in the form of a rolled-up conical surface or truncated cone surface, the blank is rolled up into a cone or truncated cone so that connecting regions (22) of the blank overlap and the overlapping connecting regions (22) are pressed.