DE10243971A1 - Catalyst supporting body, for cleaning exhaust gases from mobile combustion engines, comprises partially structured sheet metal foil, and sheet casing which radially delimits supporting body from outside - Google Patents

Abstract

Catalyst supporting body (1) comprises a partially structured sheet metal foil (2), and a sheet casing (3) which radially delimits the supporting body from the outside. The sheet casing has openings (6) through which exhaust gas can pass in a peripheral region (5). An Independent claim is also included for a housing (13) for a catalyst supporting body.

Description

The present invention relates to a catalyst carrier body, which at least one at least partially structured sheet metal foil and comprises a cladding sheet, the at least partially structured Sheet metal foil essentially delimiting channels running parallel to an axis. Such catalyst carrier body in particular for cleaning exhaust gases from mobile internal combustion engines used.

Irri train of a growing Environmental awareness and stricter emissions regulations in many countries has the need amplified, not a catalytic only in motor vehicles, but also in small engines Exhaust gas cleaning. The following are small engines with a cubic capacity of less than 250 cc, especially less meant as 50 cc. Such engines come in particular in lawn mowers, chainsaws, two-wheelers or the like Applications for use.

The catalyst carrier body will coated with a catalytically active material, which ensures that wearing, that pollutants contained in the exhaust gas upon contact with it catalytically active material in more tolerable Components is implemented.

The use in particular is present such catalyst support body in handsets of interest. Such handheld devices are characterized by the fact that the user during the Use all the time carry or push yourself. Here are for example various garden tools in the foreground, such as brushcutters, motor trimmers, chainsaws, hedge trimmers etc. The wearing time of these devices is very different, but they are preferred for large systems used so that the user over a relatively long time the handheld devices not only wear, but also regarding hedges, tree structures or align and / or position lawn edges.

For this reason, there is a special interest such devices preferably easy to do. Lighter materials are being used to manufacture these handheld devices used. The housing, which houses the drive units, for example Plastic or made using magnesium alloys.

Based on this, it is an objective of the present invention an additional To enable weight reduction of such known devices with small motors. In particular, there is an inexpensive and uncomplicated weight reduction in the foreground. Also in terms of retrofitting existing ones Handheld devices or For small motors, the invention is said to be quick and effortless Ensure commitment. In addition, should the heat dissipation the heat generated during catalytic exhaust gas cleaning the catalyst carrier body improved become.

The above objects are achieved by a catalyst carrier body with the features of the claim 1 and an associated housing with the features of the claim 8th solved. Further advantageous refinements are described in the dependent claims.

According to the present invention is the catalyst support body described in the beginning Developed in such a way that the jacket sheet radially supports the catalyst carrier outward limited and has openings in at least one peripheral region. In doing so the openings exhaust gas can flow around and / or through which exhaust gas can flow his.

The desired weight loss of the handheld device or the small engine with exhaust system is thus through material savings on the catalyst carrier itself brought about. The focus here is on reducing the weight of the jacket sheet. The jacket sheet generally serves the external and internal dimensional stability of the catalyst carrier body and provides the basis for a joining technology Connection of the coated with catalytically active material, at least partially structured sheet metal foil. Due to the internal combustion engines in the exhaust gas occurring thermal and dynamic alternating stress must such a cladding sheet can be suitable, sometimes considerable loads (thermal expansion, pressure surges, aging, etc.) to resist. For this reason, the cladding sheet is in usually run more solid than the metal foils arranged inside. In this respect has a reduction the weight of the cladding sheet is of particular importance.

According to the invention, the jacket sheet has at least openings. The design of the openings as slots, pores, holes, perforations etc. is selected taking into account the prevailing loads. Furthermore, the structural integrity of the catalyst carrier body in relation to the peripheral region in which the openings are arranged must be taken into account. Under certain circumstances, the jacket sheet must be designed in certain areas without such openings in order to ensure a permanent connection of the catalyst carrier body to other components of the exhaust system. The arrangement of several openings to one another can be carried out in almost any orientation, with the same or varying spacing, with a different diameter, etc. The general arrangement of the at least one peripheral area should also be selected taking into account the intended use, such a peripheral area can be arranged, for example, near an end face of the exhaust gas inlet and / or near an end face of the outlet area of the exhaust gas. The circumferential area can extend over the entire circumference of the jacket sheet or only over partial areas. With typical arrangements of Catalysts in the muffler housings of small engines are at least partially in the exhaust gas flow or even flow around a part of the exhaust gas, because the entire exhaust gas flow is not necessarily passed through the catalyst. Here the openings cause an additional swirl and increase the heat dissipation by enlarging the outer surface of the catalyst. Depending on the type and internal structure of the honeycomb body, exhaust gas can also escape from the honeycomb body through the openings, which likewise results in better heat dissipation. Since the small dimensions of hand-held devices generally make heat dissipation more difficult, and of course outside temperatures should not be too high, and the temperature of the exhaust gas at the outlet, e.g. due to the risk of forest fires in chainsaws, must not be too high, an improved heat distribution is of great importance ,

According to a further embodiment of the catalyst carrier body proposed that the jacket sheet over the entire axial length with a Plurality of openings is provided. This means, that the above-mentioned circumferential area extends over the entire axial length of the Catalyst carrier body extends and this way one if possible size Weight reduction of the catalyst carrier body causes becomes. The many openings are preferred evenly over the Circumference or axial length distributed of the catalyst carrier body arranged to be as possible homogeneous behavior of the catalyst carrier body due to thermal or dynamic loads in any cross section of the Catalyst carrier body too guarantee. In particular, it should be ensured that a permanent connection the at least one partially structured sheet metal foil with the Jacket sheet (e.g. through solder connections) is guaranteed.

According to a further embodiment of the catalyst carrier body the at least one structured sheet metal foil in the interior of the jacket sheet arranged that the openings of the cladding sheet for a fluid can flow through are. As already explained at the beginning was formed, the at least partially structured sheet metal foil in the Channels running essentially parallel to an axis. These channels allow flow through of fluids, especially exhaust gas. Accordingly, the channels are on the one hand and the openings in the cladding sheet, on the other hand, essentially perpendicular to one another arranged. It follows from this that, under certain circumstances, a in the edge region of the catalyst carrier body Connection between the axially extending channels with the openings of the cladding sheet exist. Such an arrangement of at least a structured sheet metal foil opposite the openings of the jacket sheet leads to an improved heat dissipation of the Catalyst carrier body to the environment. This is made possible by partial exhaust gas flows through the openings flow around or flow through and so cooling of the jacket sheet and heat dissipation effect from within. This helps prevent overheating of the catalyst carrier body and Exhaust gas temperature too high during of use can be avoided. Such a solution offers particularly in the case of so-called “bypass” variants of catalytically active exhaust gas treatment systems which are characterized by the fact that a certain proportion of the exhaust gas produced on the catalyst carrier body (untreated by the latter) passed by becomes. With such "bypass" variants, it can in the edge region of the catalyst carrier body mixing operations regarding the bypassed Exhaust gas flow and through the openings escaping partial exhaust gas flows come. Due to the fact that the partial exhaust gas flows from the Inside the catalyst carrier body beforehand as a result of exothermic reactions in the catalyst carrier body temperature increase experienced, the "bypass" exhaust gas flow accordingly cooler is a quick removal of the hot exhaust gas from the inner Areas of the catalyst carrier body reinforced. can this effect can be avoided, for example because there is a risk of overheating does not exist or has particularly high requirements with regard to effectiveness of catalytic exhaust gas purification, these openings in the casing can at least partially, possibly by a clever arrangement of the Structuring of the sheet metal foil into inner areas of the opening, be closed so that the fluid or exhaust gas can pass through through the opening of the cladding sheet is not possible is.

According to a further embodiment the jacket sheet has a thickness that is less than 1 mm, in particular less 0.1 mm and preferably less than 0.05 mm. The reduction in In addition to the weight saving, the jacket sheet thickness also has the advantage that the surface specific Reduced heat capacity so that the catalyst carrier body over its entire cross-section shows an almost uniform thermal expansion behavior. In this way, thermal stresses in particular are caused greatly different thermal expansion behavior of the sheet metal foil and of the jacket sheet avoided.

It is further proposed that the area-related proportion of the openings is at least 30%, in particular at least 45% and preferably at least 60%, based on the total area (ie with the area of the openings) of the peripheral region. If the circumferential area extends, for example, over the entire axial length of the catalyst carrier body, an areal portion of at least 30% means that at least 30% of the entire circumferential surface of the catalyst carrier body is designed with openings. The size of the openings can vary greatly, with a uniform distribution of a large number of openings These are preferably round and have an average diameter which is in the range from 1 mm to 1 cm. Especially in the case of a large area of the openings, it is advantageous if the jacket has sheet metal, for example in the circumferential direction, reinforcing structures which are designed as beads, folds, etc.

According to a further embodiment it is suggested that the at least one is at least partially structured sheet metal foil by stacking and / or winding are formed into a honeycomb body with at least one smooth sheet metal foil, the for a fluid can flow through is. A plurality of structured sheet metal foils are preferred and smoother sheet metal foils first arranged alternately to each other and then together and with each other wound, wrapped, kinked or the like. This way itself (when such a catalyst carrier body is viewed from the front) The course of the metal foils in different ways: spiral-shaped, S-shaped, M-shaped, W-shaped, bent etc. The structuring of the sheet metal foil is preferably in the direction the axis of the catalyst carrier body, wherein the smooth and structured sheet metal foils repeatedly touch and channels this way form.

With regard to the preferred area of application Such reduced-weight catalyst carrier body in handheld devices these have a relatively low channel density. The channel density corresponds the number of channels based on a unit area in cross section of the catalyst carrier body. One is present Channel density of at most 600, especially at most 400 and preferably less than 200 cpsi (“cells per square inch”) are proposed. The sheet metal foils themselves are preferably of sheet metal foil thickness executed the smaller 50 μm, in particular less than 30 μm and preferably less than 15 μm is.

According to yet another embodiment of the Has catalyst carrier body the at least one at least partially structured sheet metal foil, in particular also the at least one smooth sheet metal foil, holes. "Holes" in the above sense include a variety of different configurations of openings, Slits, pores etc. You can on the one hand create a connection between adjacent channels, on the other hand, for example, due to the catalytically active Coating on the metal foils must be closed. It is essential that through the holes a further reduction in weight of the catalyst carrier body and an improved heat distribution is effected inside.

According to another aspect of Invention becomes a housing for one Catalyst carrier body described above, in which the Catalyst carrier body like this is arranged that he is outside at least in some areas. exhaust gas can flow around and / or exhaust gas emerge from its openings and deal with the rest Exhaust gas can mix.

The fixation of the catalyst carrier body in and / or on the housing can by means of known joining technology Process (solder connection, Weldment Adhesive connection etc.). The end of the catalyst carrier body can be on a Recording put on, or at least partially through the Extend the receptacle. It is usually irrelevant whether the shot is at least partially within the with openings provided circumferential area of the jacket sheet or not. The connection between the holder and the catalyst carrier body is preferably small areas perform, to be an unwanted impairment the thermal expansion behavior of the catalyst carrier body avoid.

It is particularly advantageous that the receptacle has at least one passage that flows through the Gap for ensures a fluid. Such a design of the recording ensures implementation the above-mentioned "bypass" exhaust system Line section is therefore part of the exhaust system through which the produced gas is led into the environment. The incoming exhaust gas is now divided in such a way that a large, preferably internal, Partial exhaust gas stream passes through the catalyst carrier body and thereby is implemented while one, preferably outside horizontal, partial exhaust gas stream passes through the passages of the receptacle and is thus guided past the catalyst carrier body. The share of the "bypass" partial exhaust gas flow is preferably less than 20% of the total amount of exhaust gas. Through the openings a maximum of 1/10, in particular a maximum of 1/20, occur in the jacket sheet, of the inner partial exhaust gas flow to the outside and mix with the "bypass" exhaust gas partial flow.

The invention will now be as follows based on a drawing explained. However, the invention is not particularly preferred to that shown embodiment limited..

1 shows a perspective and schematic of an embodiment of the catalyst carrier body according to the invention 1 in one housing 13 , The housing 13 includes a recording 14 that in a line section 15 is arranged. A line section can of course be understood to mean any form of a housing part or a silencer. The catalyst carrier body 1 is in the recording 14 fixed so that between the catalyst carrier body 1 and the line section 15 a space or gap 16 is formed, which is preferably a gap width 17 of at least 1 mm but is usually much larger. The recording 14 includes a large number of passages evenly distributed over the circumference 18 that flow through the gap 16 allow with exhaust gas. The flow direction 20 is by the arrows in the 1 characterized.

The catalyst carrier body 1 includes here a structured sheet metal foil 2 and a smooth sheet metal 9 that spiral to a honeycomb body 10 wrapped and inside a cladding sheet 3 are arranged. Using the structured sheet metal 2 and the smooth tin foil 9 are a plurality of essentially parallel to an axis 11 running channels 12 limited. That on the face 4 Impinging exhaust gas flows through the catalyst carrier body 1 therefore in the direction of flow 20 parallel to the axis 11 , The sheet metal foils preferably have a foil thickness 19 that is smaller than 50 μm. The surfaces of the metal foils 2 . 9 are usually provided with a catalytically active coating (eg platinum-impregnated wash coat), so that pollutants in the exhaust gas flowing through the catalyst carrier body are converted into harmless substances upon contact with the catalytically active composition.

This is the catalyst carrier body to reduce weight 1 radially outwardly bound sheet metal 2 in a peripheral area 5 with a variety of openings 6 Mistake. In the illustrated embodiment, the peripheral area extends 5 not over the entire axial length 7 of the catalyst carrier body 1 , The cladding sheet 3 also has a thickness 8th , which is preferably less than 1 mm. The sheet metal foils are also used to further reduce weight 2 . 9 with holes 21 Mistake.

The catalyst carrier body according to the invention is suitable are particularly suitable for use in hand-held tools, which are carried out with a mobile internal combustion engine. Here is the use in garden tools such as chainsaws, hedge trimmers and the like in the foreground. The features mentioned above the invention can be combined with one another in any meaningful manner, so the benefits here only in the context of concrete embodiments explained can be combined in further variants.

1

The catalyst support body

2

structured metal sheet

3

shell plate

4

front

5

peripheral region

6

opening

7

axial length

8th

thickness

9

smoothness metal sheet

10

honeycombs

11

axis

12

channel

13

casing

14

admission

15

line section

16

gap

17

gap width

18

passage

19

film thickness

20

flow direction

21

hole

Claims (8)

Catalyst carrier ( 1 ) comprising at least one at least partially structured sheet metal foil ( 2 ) and a cladding sheet ( 3 ), the at least partially structured sheet metal foil ( 2 ) essentially parallel to an axis ( 11 ) running channels ( 12 ) limited, characterized in that the jacket sheet ( 3 ) the catalyst carrier body ( 1 ) limited radially outwards and at least in one peripheral area ( 5 ) openings through which exhaust gas can flow and / or around which ( 6 ) having. Catalyst carrier ( 1 ) according to claim 1, wherein the jacket plate ( 3 ) an axial length ( 7 ), characterized in that the jacket sheet ( 3 ) over the entire axial length (7) with a large number of openings ( 6 ) is provided. Catalyst carrier ( 1 ) according to claim 1 or 2, characterized in that the at least one structured sheet metal foil ( 2 ) inside the casing sheet ( 3 ) is arranged that through the openings ( 6 ) of the cladding sheet ( 3 ) Exhaust gas can escape. Catalyst carrier ( 1 ) according to one of the preceding claims, characterized in that the jacket sheet ( 3 ) a thickness ( 8th ) which is less than 1 mm, in particular less than 0.5 mm and preferably less than 0.2 mm. Catalyst carrier ( 1 ) according to one of the preceding claims, characterized in that the areal portion of the openings ( 6 ) based on the total area of the circumference ches ( 5 ) is at least 30%, in particular at least 45% and preferably at least 60%. Catalyst carrier ( 1 ) according to one of the preceding claims, characterized in that the at least one at least partially structured sheet metal foil ( 2 ) by stacking and / or winding with at least one smooth sheet metal foil ( 9 ) a honeycomb body ( 10 ) forms, which can be traversed by a fluid. Catalyst carrier ( 1 ) according to one of the preceding claims, characterized in that the at least one sheet metal foil ( 2 ) also holes ( 21 ) having. Casing ( 13 ) for a catalyst carrier body ( 1 ) according to one of the preceding claims, characterized in that the catalyst carrier body ( 1 ) is arranged in the housing such that exhaust gas can flow around it on the outside and / or that the openings ( 6 ) escaping exhaust gas can be removed with the remaining exhaust gas.