DE9315010U1 - Carrier body for exhaust gas catalysts - Google Patents

Description

Description:

The invention relates to carrier bodies with internal channels which are used for the catalytic purification of exhaust gases from Internal combustion engines are coated with precious metal, according to the preamble of claim 1.

Support bodies for exhaust gas catalysts with a large number of axially directed, elongated, honeycomb-shaped channels are known. One type of support body consists of a rigidly extruded, fired ceramic, another type of corrugated sheet and a smooth sheet, which are placed on top of one another and wound up in a spiral shape. The present invention relates to the latter type.

The cross-section of the carrier body depends on the engine power or the expected maximum exhaust gas throughput. The length of the carrier body, on the other hand, depends essentially on the speed at which the catalytic reaction takes place. The exhaust gas must remain in the area of the catalytically effective Ede Imeta L I coating until practically all of the pollutants have been converted. Since the flow conditions in the honeycomb-shaped channels are almost exclusively laminar, the catalytic reaction is relatively slow, resulting in the well-known relatively long carrier bodies. For this reason, the conventional carrier bodies have a relatively high volume, which in turn results in large housings and correspondingly high manufacturing costs.

There are already initial solutions proposed for ceramic carrier bodies that allow the length of the carrier bodies to be reduced by at least 25% while maintaining the same cleaning effect. However, there is currently no such solution for carrier bodies made of sheet metal.

The present invention is therefore based on the object of further developing the carrier bodies mentioned at the beginning, manufactured using corrugated metal sheet, in such a way that at least an equally good cleaning effect is achieved with shorter carrier bodies.

This object is achieved by a generic carrier body with the features according to the characterizing part of claim 1.

Due to the fact that in the solution according to the invention two corrugated metal sheets are placed on top of each other, with the embossings forming an angle to each other, the formation of parallel, elongated channels is prevented. Instead, the various sub-channels in the upper sheet and the lower sheet are connected to each other, with the gas flow repeatedly hitting edges and intersections, so that vortices are constantly generated and partial gas flows are mixed with each other. Instead of the laminar flow, a largely turbulent flow is created in which the catalytic reaction takes place much more quickly, so that complete catalytic purification is achieved with considerably shorter installation lengths.

In many cases it may be sufficient to simply stack the corrugated sheets on top of each other in a suitable housing. Identical sheets can be used, each with an alternating orientation to each other.

According to another development of the invention, the sheets can be connected to one another at the contact points, for example by means of a welded joint. This increases the mechanical strength.

It is also possible to use rectangular sheets and connect them gas-tight at two parallel edges. This forces the gas flows that flow into one of the partial channels on the inlet side to pass into other partial channels.

Finally, it is possible to wind two superimposed metal sheets in a spiral, similar to conventional metal carrier bodies, creating a carrier body with a circular or elliptical cross-section.

However, the technology according to the invention also allows a new variant of carrier bodies. For this purpose, metal sheets are used that have a central opening. If, for example, circular metal discs are stacked on top of one another and an exhaust pipe is allowed to open into the central opening, a carrier body is obtained through which the exhaust gases flow radially, either from the outside to the inside or from the inside to the outside. The latter variant has the advantage that the heat in the exhaust gases is concentrated in the center of the carrier body, which heats it up more quickly, so that the temperature required for the catalytic reaction is quickly reached after a cold start of the engine.

The invention will be explained in the form of exemplary embodiments using the drawings. They show

Fig. 1 shows in perspective the basic principle according to which the carrier bodies are constructed,

Fig. 2 shows a perspective view of a first support body with a rectangular base,

Fig. 3 shows a perspective view of a carrier body

with a circular base, made from two spirally wound sheets,

Fig. 4 shows section IV of Fig. 3 on an enlarged scale,

Fig. 5 a longitudinal section through a catalyst carrier body made of stacked, circular disk-shaped sheets with a central exhaust pipe and radial gas flow,

Fig. 6 is a plan view of a first

circular disk-shaped sheet with white sheet-like

embossings, Fig. 7 a plan view of a second

circular disk-shaped sheet with white laminations embossings,

Fig. 8 is a plan view of a third

circular disc-shaped sheet metal with corrugated iron-like embossings,

Fig. 9 is a plan view of a fourth

circular disc-shaped sheet with white LI-sheet-like embossings,

Fig. 10 a plan view of a rectangular sheet with corrugated sections,

Fig. 11 is a side view of the sheet of Fig. 10 and

Fig. 12 is a front view of a carrier body made from the sheet metal of Fig. 10 and 11.

Fig. 1 shows two corrugated sheets 1, 1 ^' which are placed on top of each other in such a way that the embossings form an angle to each other. The two sheets 1, 1' therefore have

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only point contact with each other. The partial channels in the two plates 1, 1' are therefore connected to each other in many ways, so that an exhaust gas flow 3 entering a partial channel is divided into several partial flows 3' on the outlet side. There is therefore a constant mixing of all partial flows, with additional vortices being created at the intersection points and the edges of the plates 1, 1', so that an overall turbulent flow prevails, which causes a high catalytic reaction rate.

Fig. 2 shows a further development of the basic principle shown in Fig. 1 to form a carrier body. A total of four alternately stacked sheets 1, 1' can be seen here, which are each connected to one another in a gas-tight manner at two parallel side edges 2. The partial channels ending in the side edges 2 are thus closed, so that the corresponding partial gas flows 3, 3 ^' are forced to pass into neighboring channels.

Fig. 3 shows a complete carrier body 4 with a circular base, made from two embossed sheets 10, 10', wound into a spiral, whereby the short side edges 2 can again be connected to one another in a gas-tight manner.

Fig. 4 shows an enlarged view of section IV from Fig. 3. You can see arched embossed sheets 10, 10' with their embossings at an angle to each other. The arched embossing enables the winding of the sheets 10, 10' and forces a constant change in direction of the exhaust gas flows with improved turbulence.

Fig. 5 shows a second embodiment of a support body 5 for the catalytic purification of exhaust gases in longitudinal section. This support body 5 consists of a

Stack of circular disk-shaped sheets 7, 7', as shown in Fig. 6 and 7. The two sheets 7, 7' can be identical if care is taken when stacking to ensure that the orientation of their embossing is alternated. In any case, this results in a radial flow direction of the exhaust gases, with the partial channels in the sheets 7, 7' forming an angle to the main radial flow direction of the exhaust gases.

As can be seen in Fig. 5, an exhaust pipe 8 is inserted into the central opening of the embossed sheet metal disks 7, 7', which is closed at the end but has radial openings so that the exhaust gas can flow into the partial channels between the sheets 7, 7' in accordance with the flow arrows.

If, as shown in the drawing, the exhaust gas flow 3 is directed from the inside to the outside, the heat contained in the exhaust gases coming from the engine is concentrated in the center of the carrier body 5, so that it reaches the operating temperature required for catalytic cleaning relatively quickly. Such a carrier body therefore not only has a reduced volume but also a high response speed. In addition, its manufacture is relatively simple, so that the manufacture of space- and cost-saving exhaust gas catalysts is possible.

Fig. 8 shows a top view of a third circular disk-shaped sheet 9 with arched corrugated sheet-like embossings. This type of embossing has the advantage over those in Figs. 6 and 7 that the flow cross-section of the channels is approximately constant over the entire length.

Fig. 9 shows a plan view of a fourth

circular disk-shaped sheet 11 with concentric circular embossings. This sheet 11 is used

in connection with one of the sheets 7, 9 according to Fig. 6 or

Fig. 10 as a top view and Fig. 11 as a side view show an elongated, rectangular sheet 1'' with corrugated sheet-like embossed sections that alternate with unembossed sheet-metal sections 2'.

Fig. 12 shows a front view of a carrier body made from the zigzag-folded sheet metal 1'' of Fig. 10 and 11. This carrier body corresponds to that of Fig. 2, whereby thanks to the special manufacturing process the gas-tight side seal in the edge areas 2' is self-adjusting.

Claims (10)

Protection claims: 1. Support body (C 4 , 5) with internal channels which are coated with precious metal for the catalytic purification of exhaust gases from internal combustion engines, manufactured using metal sheet (1, 1', 1'¹; 7, 7';9; 10, 10'; 11) which is embossed like a corrugated sheet, characterized in that at least two embossed sheets (1, 1 ¹ , 1'¹; 7, 7';9; 10, 10'; 11) are placed on top of one another in such a way that their embossings run at an angle to one another. 2. Support body according to claim 1, characterized in that the sheets (1, 1', 1"; 7, 7'; 9; 10, 10'; 11) are connected to one another at the contact points, e.g. soldered or welded. 3. Support body according to claim 1 or 2, characterized in that identical sheets (1, 1', 1 ^Ti ; 7, 7';9; 10, 10') are placed on top of one another with alternating orientation. 4. Carrier body according to claim 1 or 2, characterized in that a sheet (1 ^tT ) is folded in an zigzag shape. 5. Support body according to claim 1, 2 or 3, characterized in that the embossings of the metal sheets (9; 10, 10') are curved in an arc shape. 6. Support body according to one of claims 1 to 3 or 5, characterized in that two sheets (10, 10') are wound spirally. 7. Support body according to one of claims 1 to 5, characterized in that the sheets (1, 1', 1 ¹ '; 10, 10') are rectangular and connected to one another at two parallel edges (2). are connected gas-tight. 8. Support body according to one of claims 1 to 3 or 5, characterized in that the sheets (7, ⁷¹ ; 9; 10; 11) have a central opening (6). 9. Support body according to claim 8, characterized in that the embossings of a sheet (11) form concentric circles, ellipses or the like. 10. Support body according to claim 8 or 9, characterized in that circular ring-shaped sheet metal disks (7, 7'; 9, 10) are stacked and that an exhaust pipe (8) opens into their central opening (6).