EP1012455B1 - Catalytic converter for a small-size engine - Google Patents

Description

The present invention relates to a catalytic converter for a Small engine, in which in a silencer housing close to the engine arranged a honeycomb body coated with catalytically active material is.

In the wake of increasing environmental awareness and stricter emissions regulations in many countries the need has increased, not a catalytic only for motor vehicles, but also for small engines Exhaust gas cleaning. Below are small engines Engines with a displacement of less than 250 cc, especially less meant as 50 cc. Such motors occur particularly in lawn mowers, Chainsaws, portable generators, two-wheelers and the like Applications on. Especially with chainsaws, lawnmowers and The person operating the device is often found in other garden tools over a longer period directly in the exhaust area of the small engine, which is why catalytic exhaust gas cleaning is particularly important.

DE-OS 38 29 668 is already an example of an exhaust silencer specified for two-stroke engines, which one inside contains catalytic converter for exhaust gas cleaning.

EP 0 470 113 B1 also discloses a metallic catalyst carrier body known, in particular for attachment in the partition of a Muffler housing is suitable.

The described arrangements for catalytic exhaust gas purification of small engines require specially manufactured honeycomb bodies, their manufacture, Catalytic coating and installation require a relatively large number of work steps and therefore compared to the small engine itself and an associated one Device are relatively expensive. In order to further spread the But it is catalytic exhaust gas cleaning for small engines necessary to dramatically increase the cost of such emission control devices to reduce.

The object of the present invention is therefore a catalytic converter for a small engine that is very inexpensive to manufacture, as small as possible constructive changes to existing small motors and their Exhaust systems require, and yet a significant proportion of pollutants can catalytically remove from the exhaust gas.

A catalytic converter according to the Claim 1, wherein a corresponding manufacturing method in claim 11 is specified. Advantageous configurations are in the dependent Claims specified.

Catalytic converters usually contain honeycomb bodies to order in one Partial volume of the exhaust system has a sufficiently large surface area for one To provide catalytic implementation. Such honeycomb bodies are particularly made of sheet metal, at least part of which Metal sheets is structured so that it is permeable to exhaust gas Channels result. In the simplest case, alternating smooth and wavy Sheet metal layers used. However, come for the present invention a variety of structures, so that sheet metal layers with two different corrugations or sheet layers with alternating oblique to each other arranged corrugations can be used. In the state of the It has hitherto been customary for technology to have a partial volume provided for the honeycomb body to be filled as evenly as possible with channels, all known Manufacturing processes avoid it as much as possible to deform on ducts when installing the honeycomb body in an exhaust system or destroy. Honeycomb bodies are sometimes under one Bias is inserted into a casing tube or housing, however the channels generally not or only to a small extent plastically deformed. According to the solution according to the invention, this is the way for catalytic converters of small engines left to manufacture to simplify drastically. Muffler housings for small engines show in generally a larger volume than for the accommodation of a Catalyst carrier body is necessary for complete exhaust gas purification. It is therefore not based on the optimal use of the available volume or minimizing an enclosure. So you can accept that part of the volume partly through plastically deformed channels is blocked without this affecting the function or the exhaust gas cleaning. This opens up the possibility of simply being a honeycomb body stacked, wound or otherwise folded stacks of with catalytic active material to use coated sheet metal layers, which under plastic deformation of a large proportion of the cells, for example 10, 20 or up to 30%, is squeezed into the silencer housing, so that it is at least a partial volume of the muffler housing completely fills.

As in the following, this method has preferred exemplary embodiments is described, many manufacturing advantages and leads to a simple but durable catalytic converter.

In general, a silencer housing for small engines consists of two or more individual parts, especially half shells and a partition, which by means of a simple connection process, e.g. B. flanging or Weld, be joined together. These housing parts can Assembling used simultaneously for the shaping of the honeycomb body without additional tools. A stack of Sheet layers with a larger volume than the partial volume to be filled in Muffler housing is easy to put on when assembling the housing the intended place and when assembling the housing parts in its final position and shape squeezed. Even if 15 to 30% of the Channels are plastically and / or elastically deformed, namely on the side ends of the stack and in the outer edge areas, so stay enough cells permeable to gas, so that an effective catalytic Cleaning is ensured.

To prevent the honeycomb from slipping in the silencer housing in the direction of gas flow to avoid the side ends of the stack in a preferred embodiment on or in the walls of the housing be supported.

It is also important for a simple manufacturing process that the sheets are in front the installation in the silencer housing already with catalytically active Material are coated, either by already for the entire production coated sheets can be used, or by placing a prefabricated stack of sheet metal layers as a whole is coated.

A major advantage of the catalytic converter according to the invention is that the considerable deformation of the channels is partly plastic and is partially elastic, so that the honeycomb body is under a prestress remains in all operating conditions, especially thermal Alternating loads, loosening of the sheet layers prevented. In general is in a catalytic converter according to the invention The honeycomb body should be under maximum prestress, since it is everywhere over the Elastic limit is deformed. This prevents relative movements between the sheet layers even with decreasing temperature Elasticity.

At this point it should be noted that for the present invention especially sheet metal layers with so-called transverse microstructures come into consideration, which are known in the prior art. This Microstructures increase the effectiveness in catalytic conversion and also cause the sheet metal layers to clamp together, so that these themselves under the high elastic bias cannot move against each other under the most unfavorable conditions. This also applies if not all sheet layers, but only a part its ends are attached to the muffler housing.

It is particularly favorable if the one to be squeezed into the muffler housing Stack in its original form to the shape of the form to be filled out Partial volume and the degree of deformation to be expected during crushing of the individual areas is adapted, although the volume of the Stacks at least 5%, preferably at least 10% larger than that partial volume to be filled.

Therefore, different shapes come as cross-sectional shapes for a stack into consideration, in particular rectangle, trapezoid, oval or in individual cases more irregular shapes. It should also be noted that individual sheet layers, the ends of which are bent along the ends of the stack should be as less bent sheet metal layers if their ends after the Crushing process should extend to the housing wall or a partial joint.

It is particularly preferred for those composed of at least two parts Muffler housings the crimped ends of the stack in the joint between these parts pinch to the honeycomb body to fix overall. This can be the case with single sheet metal Stacking, as well as in the case of wrapped from one or more sheets, folded or meandering stacks after crushing of the ends. The ends of the stack in the previously used for assembling the muffler housing Technology to be included, so that the attachment, for example, by Flanging, welding with a weld seam or by spot welding can be done. Especially when flanging, but also when embedding in a weld seam, the catalytically active coating generally interferes not on the sheets, so that no additional processing steps whose removal is required.

Figur 1

einen Längsschnitt durch ein Schalldämpfergehäuse mit schematisch angedeutetem Einbauort eines katalytischen Konverters,

Figur 2

im Querschnitt die Teile eines Schalldämpfergehäuses einschließlich eines Stapels kurz vor dem Zusammenbau,

Figur 3

einen Querschnitt entlang der Schnittlinie III-III in Figur 1 durch ein Schalldämpfergehäuse nach dem Zusammenbau und

die Figuren 4, 5, 6, 7 und 8 verschiedene Formen von Stapeln zumindest teilweise strukturierter Blechlagen.Advantageous refinements and exemplary embodiments of the invention are explained below with reference to the drawing, but the invention is not restricted to the exemplary embodiments shown. Show it:

Figure 1

2 shows a longitudinal section through a silencer housing with a schematically indicated installation location of a catalytic converter,

Figure 2

in cross section the parts of a silencer housing including a stack shortly before assembly,

Figure 3

a cross section along the section line III-III in Figure 1 by a silencer housing after assembly and

Figures 4, 5, 6, 7 and 8 different forms of stacks of at least partially structured sheet metal layers.

Figure 1 shows schematically in longitudinal section a silencer housing 3 for a small engine. The exhaust gas enters the exhaust gas inlet 1 Lower part 3.2 of the muffler housing, from where it through openings in a partition 3.3 in the upper part 3.1 of the muffler housing. From here it flows through the channels 7 of a honeycomb body 4 and arrives then to the exhaust outlet 2. Upper part 3.1 and lower part 3.2 of the muffler housing and the partition 3.3 are in the area of a partial joint 3.4 connected to each other, for example by flanging or by a Weld.

Figure 2 illustrates schematically in cross section the joining of Upper part 3.1, lower part 3.2, partition 3.3 of the silencer housing and a stack 8 of sheet metal layers 5, 6, the process of joining is indicated by arrows. The stack 8 is in the present exemplary embodiment from alternately arranged individual smooth sheet metal layers 5 and corrugated sheet metal layers 6, which together form a variety of for form the exhaust gas-permeable channels 7. The sheet layers 5, 6 are with coated catalytically active material 10. This coating can either already in a continuous process before all other processing steps be applied to the sheet metal layers 5, 6, or after Layers of the stack 8 are applied together.

Figure 3 shows in cross section along the line III-III in Figure 1 in essentially completely assembled silencer housing with crimped Honeycombs. It can be seen that the lateral ends 9 of the in FIG stack 8, still undeformed, are now squeezed together, and also numerous in the edge areas of the honeycomb body Channels 7.1 are plastically deformed. Nevertheless remain, especially in inner area of the honeycomb body, still not sufficiently plastically deformed Channels which are used for the catalytic conversion of Sufficient exhaust gas. However, these channels 7 are through on the whole Honeycomb body squeezing forces deformed considerably elastically, so that the whole honeycomb body is under considerable prestress. The pinched lateral ends 9 of the sheet stack are between the upper part 3.1 and partition 3.3 of the silencer housing and can included in the usual connection technology of the silencer housing become. As shown on the right side of Figure 3, this can be a Flanging will be 3.5. But one is also possible on the left side of the Figure 3 indicated weld connection 3.6, which the ends of the sheet metal layers 5, 6 of the upper part 3.1, the lower part 3.2 and the partition 3.3 involves.

In Figures 4, 5, 6, 7 and 8 are different starting forms for the honeycomb body 4 to be integrated into the silencer housing 3 as a selection of the total possible shapes. Figure 4 shows one Trapezoidal sheet metal stack 11, from smooth sheet metal layers 5 and corrugated Sheet metal layers 6, 11 in the lateral end regions 9 of the sheet stack those sheet layers are longer, the ends of which are up to the parting line have a longer route after assembly. That way ensures that the ends of practically all sheet metal layers are held securely can be. 5 shows a meandering stack of sheets 12.1, in which a corrugated sheet layer 6 is layered in a meandering manner, whereby individual smooth sheets 5 are arranged between the individual layers are. A similar configuration is shown in Figure 6, there however, only a single sheet, which is smooth and corrugated in sections is layered to a meandering stack of sheets 12.2. Figure 7 shows an oval sheet stack 13 of a smooth 5 and a corrugated Sheet 6 as a starting stack. Such a stack can be conventional Way by flattening a wound with a cylindrical cavity spiral sheet stack can be achieved.

Figure 8 finally shows a particularly preferred embodiment, at who only included the smooth sheet metal layers 5 in the connection of the parting line should be. For this reason, the ends of the smooth sheet metal layers to different distances, according to their way to the parting line. The corrugated sheet layers 6 are shorter and in their respective length Cross-sectional shape of the muffler housing adapted and again with a certain excess of volume, which is later replaced by plastic Deformation is reduced, equipped. To prevent the curled from slipping To avoid sheet metal layers 6 in the finished honeycomb body in the gas flow direction, are the smooth 5 and the corrugated sheet layers 6 with a positive fit interlocking structures. Are particularly suitable for this microstructures running transversely to the flow direction, such as those from the State of the art are known.

The present invention creates the by inexpensive manufacturing technology Possibility of broad-based exhaust gas catalytic converters even for small engines to be able to apply to the environment and the operating personnel of the Relieve small engines.

LIST OF REFERENCE NUMBERS

1

exhaust inlet

2

exhaust outlet

3

muffler housing

3.1

Top part of the silencer housing

3.2

Lower part of the silencer housing

3.3

Partition in the silencer housing

3.4

parting

3.5

beading

3.6

joint weld

4

honeycombs

5

smooth sheet metal layer

6

corrugated sheet layer

7

channel

7.1

deformed channel

8th

Stack of sheet metal layers

9

crushed side end of the sheet stack

10

catalytically active material (coating)

11

trapezoidal sheet stack

12.1

meandering stack of sheets with inlaid smooth sheet layers

12.2

meandering stack of sheets from different sections

13

oval sheet stack

14

Sheet stack with protruding smooth sheet layers

Claims (15)

1. A catalytic converter in a silencer housing (3) for a small engine, whereby a honeycomb body (4) being coated with catalytically active material (10) and made of at least partly structured sheet metal layers (5, 6) with channels (7) for passage of an exhaust gas is arranged in a silencer housing (3) proximate to the engine, so that at least a predominant portion of the exhaust gas of the small engine must flow through said honeycomb body (4), characterized in that, said honeycomb body (4) is a layered, wound or folded stack of sheet metal layers (8), being squeezed into the silencer housing (3) with plastic deformation of at least 10 %, preferably 20 to 30 %, of the channels (7), so that said honeycomb body (4) fills at least completely a partial volume of said silencer housing (3).
2. The catalytic converter according to claim 1, characterized in that the stack (8) has lateral ends (9) retained on or in the walls of said housing (3).
3. The catalytic converter according to claim 1 or 2, characterized in that said sheet metal layers (5, 6) are coated with said catalytically active material (10) before fitting in said silencer housing (3).
4. The catalytic converter according to claim 1, 2 or 3, characterized in that said channels (7.1) are partly plastically and partly elastically deformed, causing said honeycomb body (4) to remain under a pretension for preventing loosening of said sheet metal layers (4, 5) under all operating conditions, particularly varying thermal stresses.
5. The catalytic converter according to one of the preceding claims, characterized in that the stack (8) has an initial shape matching a shape of said partial volume of said silencer housing (3) to be filled, but with a volume which is at least 5 % greater, preferably at least 10 % greater.
6. The catalytic converter according to one of the preceding claims, characterized in that said stack (8) has a rectangular cross-section before insertion in said silencer housing (3).
7. The catalytic converter according to one of the claims 1 to 6, characterized in that the stack (11) has a trapezoidal cross-section before insertion in said silencer housing (3).
8. The catalytic converter according to one of the claims 1 to 6, characterized in that the stack (13) has an oval cross-section before insertion in said silencer housing (3).
9. The catalytic converter according to one of the preceding claims, characterized in that said stack (8; 11; 14) is sheeted of individual at least partly structured sheet metal layers (4, 5) the ends of which are squeezed together (9) and fixed onto said silencer housing (3), preferably clamped in a seam (3.4) between two parts (3.1, 3.3) of said silencer housing (3).
10. The catalytic converter according to one of claims 1 to 8, characterized in that the stack (11; 12.1; 12.2; 13) is formed from one or several at least partly structured, meander-shaped or oval wound metal sheets (5, 6), the lateral ends (9) of said stack (11; 12.1; 12.2; 13) each being squeezed together and fixed to said silencer housing (3), preferably being clamped between two parts (3.1, 3.3) of said silencer housing (3).
11. A method for manufacturing a catalytic converter in a silencer housing (3) for a small engine, comprising the following steps:

    a stack (8; 11; 12.1; 12.2; 13; 14) of at least partly structured sheet metal layers (5, 6) is formed, which comprises channels (7) for passage of an exhaust gas,

    the stack (8; 11; 12.1; 12.2; 13; 14) is squeezed into a partial volume of the silencer housing (3) with plastic deformation of at least 10 %, preferably 20 to 30 %, of the channels (7), thereby completely filling the partial volume.
12. The method according to claim 11, characterized in that the stack (8; 11; 12.1; 12.2; 13; 14) comprises lateral ends (9), said lateral ends (9) of the squeezed stack (8; 11; 12.1; 12.2; 13; 14) being fixed on or in the wall of the silencer housing (3).
13. The method according to claim 11 or 12, characterized in that the metal sheets (5, 6) are coated with catalytically active material (10) before the formation of the stack (8; 11; 12.1; 12.2; 13; 14) or at least before the installation in the silencer housing (3).
14. The method according to claim 11, 12 or 13, characterized in that the squeezing of the stack (8; 11; 12.1; 12.2; 13; 14) is caused by assembling together two or more housing parts (3.1 3.2, 3.3) of the silencer housing (3) between which the stack (8; 11; 12.1; 12.2; 13; 14) is incorporated.
15. The method according to one of claims 11 to 14, characterized in that the stack (8; 11; 12.1; 12.2; 13; 14) is manufactured to be slightly wider than the silencer housing (3) causing the lateral ends (9) of the stack (8; 11; 12.1; 12.2; 13; 14) to project from one or two sides after squeezing and joining the silencer housing (3) and incorporating said lateral parts (9) in the joining of the silencer housing parts (3.1, 3.2, 3.3) by beading the edges (3.5) or by a joining technique.

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