DE10237512C1 - Metallic honeycomb body used as catalyst carrier for treating IC engine exhaust gases or for adsorber material has holes in partial volume of axial length and specified distance of radial extension in all sheet layers - Google Patents

Abstract

A metallic honeycomb body has holes (6) in a partial volume of at least 55% of the axial length (L) and at least 20 mm of the radial extension in all sheet layers (1). The holes each have a surface area of 1-120 mm2. The sheet layer surface in the partial volume is reduced by the holes by 10-80%, preferably 35-60%, compared with a non-perforated sheet layer. The partial volume has a distance (R2, R3) from the front sides (12, 13) of the honeycomb body so that no holes touch or undercut the front side edges of the sheet layers.

Description

The present invention relates to a metallic honeycomb body, in particular a honeycomb body for an exhaust system of an internal combustion engine. Such wa body is used as a carrier for catalytically active material and / or for adsor used material and similar applications.

Metal used in particular for cleaning exhaust gases in motor vehicles Honeycomb bodies have to meet very different requirements, some of them There must be compromises between contradicting requirements gene can be achieved. First of all, such honeycomb bodies serve to provide the largest possible surface on which the desired catalytic Reactions or adsorption processes can take place. In many applications len a low heat capacity is desired so that the honeycomb body either quickly warms up to its desired operating temperature or else also have a high heat capacity so that it can keep the operating temperature for a long time can keep, but do not heat up too quickly to high temperatures leaves. Of course, such an arrangement must generally be mechanically stable, i.e. H. withstand a pulsating gas flow and mechanical loads can withstand the movement of the vehicle. Its material must be resistant to high temperatures and can at least be processed in such a way that the desired honeycomb body structures can be produced easily and inexpensively are. In many cases there are also special structures within the honeycomb body pers needed to influence the flow, for example for better contact surface or for cross-mixing. Finally, a suitable one Honeycomb bodies can be mass-produced inexpensively.  

Many aspects of the state of the art contain individual aspects of the The above problems are described in detail.

A distinction is made between two typical designs for metallic honeycombs by. An early design, of which DE 29 02 779 A1 shows typical examples, is the spiral design, which is essentially a smooth and a corrugated Lay the sheet metal layer on top of each other and wind it up in a spiral. At a The honeycomb body is made of a variety of alternate designs ordered smooth and corrugated or differently corrugated sheet layers built, the sheet metal layers initially form one or more stacks that with are swallowed up. The ends of all sheet metal layers come out to lie and can be connected to a housing or casing tube, which creates numerous connections that increase the durability of the honeycomb body increase pers. Typical examples of these designs are in EP 0 245 737 B1 or WO 90/03220. The Blechla has also been known for a long time equipped with additional structures to influence the flow and / or cross-mixing between the individual flow channels to reach. Typical examples of such configurations are WO 91/01178, WO 91/01807 and WO 90/08249. Finally, there are honeycomb bodies in a conical design, possibly with additional structures for influencing flow. Such a honeycomb body is for example in the WO 97/49905. In addition, it is also known in a honeycomb body to leave a recess for a sensor, especially for the sub Bring a lambda probe. An example of this is in DE 88 16 154 U1 wrote.

It has also been known for a long time, slotted sheets; especially Streckme to use tall and similar slot structures for honeycomb bodies. An over look over different shapes and arrangements of openings in sheet metal layers  of catalyst support bodies are US 5,599,509 with that cited State of the art. Openings are used there specifically to increase the heat capacity in the front area of a honeycomb body compared to the rear area to reduce.

Although the extensive state of the art, many different developments direction allowed, a few development trends developed. one of these trends is the development towards ever thinner metal foils with a small amount of material and low heat capacity a large surface to be able to provide. The obvious disadvantage of this direction of development is that the thin foils are mechanically more and more sensitive and the resulting ones made honeycomb bodies become less durable. At the same time developed Trend towards ever higher cell densities, which is within certain limits due to the ever thinner foils. To improve the exchange of materials with The surfaces of a honeycomb structure have been structured into the surfaces Influenced flow, especially so-called transverse structure tures or there were flow guide surfaces or inside a honeycomb body additional leading edges created. Although the benefits of openings in the sheet metal layers are known for cross-mixing, this became systematic Provide openings for a fluid to flow freely in one predominate the part of the catalyst volume has practically not been considered because this runs counter to the trend, ever larger surfaces in ever smaller ones To provide volumes. During slots and / or flow control surfaces Chen and similar structures do not reduce the surface in a honeycomb body gladly, numerous holes significantly reduce the surface and mean also, at least if the holes are created by removing material, an increased consumption of raw material without a corresponding increase in O surface, which also runs counter to the trend. Therefore holes were only made in Considered when performing a specific function in a specific location  should have the honeycomb body, for example the cross-mixing or Reduction of heat capacity compared to other areas.

This view was isolated for a metallic honeycomb body applicable, but it must not be overlooked that later a metallic Honeycomb body is coated with a coating material which in vie len cases also contains expensive precious metals as a catalytically active component. This means that a large surface always means a large amount of expensive ones Coating material. Experiments have surprisingly shown represents that with certain dimensions of size, distribution and density a large number of holes over a honeycomb body with a smaller surface the same good properties for catalytic conversion result as in one Honeycomb body without holes and with a larger amount of coating material rial.

The object of the present invention is therefore a metallic honeycomb body per to create by appropriate number, dimensioning and distribution of holes is particularly suitable as a carrier for a coating, in particular re with economical use of the coating material.

To solve this problem is a metallic honeycomb body according to claim 1. This honeycomb body with an axial length of sheet metal layers, which are structured so that the honeycomb body from a fluid, in particular the gas from an internal combustion engine in a flow direction from an inflow-side end face can flow through an outflow-side end face, the sheet metal layers having a plurality of openings at least in partial areas, is characterized according to the invention in that the honeycomb body has holes in all sheet metal layers in a partial volume of at least 55% of its axial length and at least 20 mm radial expansion, the following applies:
The holes each have an area of 1 and 120 mm. In the partial volume, the sheet layer surface is reduced by the holes by 10 to 80%, preferably 35 to 60%, compared to an unperforated sheet layer, the partial volume is at a distance from the end faces of the honeycomb body so that no holes touch or overlap the front edges of the sheet metal layers.

Tests have shown that a honeycomb body according to the invention also has Holes due to the improved flow properties in its interior and the resulting better mass exchange properties between Flow and surface in its effect a honeycomb body without holes comparable, may even be superior, although less coating tion material is used. The holes are so big that on the one hand they are not be sealed by coating material during coating and that they on the other hand, not clogged by particles in a fluid to be cleaned become. So it is not a question of holes like a filter for holding back processing of particles, but around openings that are free of any to be cleaned Fluid, in particular an exhaust gas from an internal combustion engine would flow through can. For technical reasons and because of the later durability it is important that the front edges are not through holes or parts of Holes are frayed, which is why the holes are spaced from the end faces should have.

As already stated, the holes have advantages rather than disadvantages, which is why partial volume with holes more than 60%, preferably more than 90% of the total honeycomb body volume. That way the positive effect is most effective.  

For mechanical and fluidic reasons, it is favorable if the holes each have an area of 5 to 60 mm ² . On this scale, they are easy to manufacture, do not interfere with a coating process and bring out the above advantages of better material exchange. Holes of this size allow good cross-mixing and also allow heat to be dissipated from the inside of the honeycomb body to the outside, not only by heat conduction, but also by heat radiation which passes through the holes into areas located further out. The larger the total area of the holes compared to the total area of the remaining sheet layers, the stronger these effects are of course.

The state of the art is almost exclusively for comparable applications Openings described in the sheet metal layers, which have angular contours. From a mechanical point of view, this is not advantageous for high alternating loads, because cracks can form from the corners of the holes. Therefore, in the present invention, rounded contours of the holes preferred, so that the boundary lines of the holes no corners, in particular have no acute angles. The holes are particularly preferably round, be oval or elliptical, although it is recommended for non-round shapes a ratio of the largest diameter to the smallest diameter of two not to exceed.

However, such holes cannot be made in a material-saving manner, such as. B. possible with expanded metal, but must be removed by removing the material an entire sheet metal layer. The preferably punched out or cut material, however, can be used to make new sheet metal layers be used.  

Depending on the type of production of the sheet metal layer, the holes can also be preferred can be left out during the manufacturing process, especially for Galva noplastic materials come into consideration. At a manufacturing procedure in which a cheap material is first produced and later by Be layers, e.g. B. with aluminum and / or chrome, it is recommended make the holes before finishing with other materials det.

Another advantage of the invention is that the heat capacity of a honeycomb body pers with holes is of course less than the heat capacity of a honeycomb body pers without holes. Conversely, this allows honeycomb bodies according to the invention to produce thicker sheet layers without the heat capacity compared to Wa body from unperforated thin sheet layers increases. According to the invention the thickness of the sheet metal layers can be between 20 and 80 μm, is preferred however, a thickness of 40 and 60 microns. The preferred range leads to a particular seren mechanical stability, especially the end faces of a honeycomb body and allows the use of proven manufacturing processes, which are very no longer allow thin foils to be applied easily. Nevertheless, the warmth mecapacity of the resulting honeycomb bodies is equal to or less than that of Wa body made of thin foils without holes.

To ensure the mechanical stability of a honeycomb body according to the invention the holes should be at least 0.5 mm apart, whereby preferably all distances between the holes are each approximately the same size should, so that no mechanical weak points arise. Foils designed in this way can be easily waves and in the other steps to manufacture of spiral or layered and intertwined honeycomb bodies.  

A honeycomb body according to the invention, such as that, also particularly preferably exists most known in the prior art, made of alternately arranged smooth and corrugated sheet metal layers or alternating different corrugated Sheet metal layers. The typical flow channels in a honeycomb body.

Due to the positive effects of the holes it is essential for good implementation properties ten of the catalytic converters that were later manufactured from the honeycomb bodies required that the honeycomb body according to the invention has an extremely high cell density to have. According to the invention, cell densities between 200 and 1000 cpsi (cells per square inch) preferred, in particular cell densities of 400 and 800 cpsi.

The use of holes in the sheet metal layers according to the invention is impaired not the usability of the sheet metal layers for most previously known additional structures for influencing flow as described in the description of State of the art have been mentioned. In particular, the perforated sheet were also with transverse structures, with inversions and / or with currents provided guidance surfaces. In general, the holes support the effect of such structures, because pressure may develop in the channels compensate for each other through the openings, additional turbulence arises and an equalization of the flow profile within the honeycomb body is effected.

In the proposed use of a hollow space of a honeycomb body introduced probe, in particular a Lambdason de, the inventive design of a honeycomb body has a particular effect otherwise positive. Since a measuring probe, in particular an oxygen measuring probe The most representative possible value of the fluid flowing in the honeycomb body cross-mixing in front of the probe is of great advantage. OF INVENTION  Honeycomb bodies according to the invention are therefore particularly suitable for applications in who introduced a lambda probe into a cavity of the honeycomb body that should.

In terms of manufacturing technology, this requires a certain amount of effort during production the sheet metal layers so that they can be used later after assembly Form cavity. Nowadays, however, this effort is numerically controlled manageable manufacturing systems. That allows at the same time, close to the No void-defining edges of the sheet layers to place around to avoid fraying the edges there too. Especially preferred therefore there are no holes in a range of 1 to 5 mm around the cavity for a measuring probe.

For the durability of a honeycomb body, it is advantageous if the individual Sheet metal layers are joined together, preferably by Brazing, which is typically done on the end faces of a honeycomb body. This is also a reason why there are no holes in the front edge areas of the Should cut sheet layers. On the other hand, the holes can also be targeted prevent glue applied to the end faces or to the end faces applied solder along the lines of contact between the sheet layers in the Inside the honeycomb body penetrates, which is often undesirable for mechanical reasons is. Holes here cause the capillary effect to end, so that the distance between the Holes from the end faces of a honeycomb body are also used for this purpose can be used to limit an area connected by soldering.

The same applies to the connection of the sheet metal layers to a casing pipe. Also there it is because of the desired very stable connection to the casing pipe cheaper if the edge areas are not cut by holes. Also here, moreover, the holes ensure that the solder is not closed by capillary action  can penetrate far into the interior of the honeycomb body, but stays right there, where it is also used to fasten the sheet metal layers.

Embodiments and details of the invention, but not to this is limited, are explained in more detail below with reference to the drawings, and show:

Fig. 1 is a sheet-metal layer for producing a honeycomb body according to the invention,

Fig. 2 is a perspective, partially broken view of a honeycomb body according to the Invention and

Fig. 3 shows a partially broken catalytic converter with an inventive honeycomb body and a cavity for a lambda probe in a schematic side view.

Fig. 1 shows a sheet metal layer 1 , which can either be smooth or corrugated, as used to build a honeycomb body according to the invention. This sheet metal layer 1 has a width L, which later determines the axial length L of a honeycomb body produced therefrom. The expansion of the sheet metal layer in the other direction depends on the construction type of the honeycomb body to be produced. It can be very long if a spirally wound honeycomb body is to be made from it, or relatively short if it was part of a stack of several such sheets 1 , which is later devoured into a honeycomb body. The thickness of the sheet metal layer 1 can be between 20 and 80 μm, preferably between 40 and 60 μm. The sheet metal layer 1 has in a partial area a large number of holes 6 , each having an area between 1 and 120 mm ² . Before are given holes 6 with a diameter between 3 and 8 mm, preferably between 4 and 6 mm. These holes 6 are arranged in a regular pattern and preferably have equal distances D7 from one another. The holes 6 are preferably round or elliptical or oval with a largest diameter R6 up to 8 mm. The distances D7 of the holes 6 are chosen so that the sheet layer surface is reduced by 10 to 80%, preferably 30 to 60%, compared to an unperforated surface. The sheet metal layer 1 has an edge region 2 on the inflow side which is free of holes 6 . An outflow-side edge region 3 is preferably also free of holes. This simplifies the processing of the sheet metal layer, enables a connection of sheet metal layers to one another in this edge region and prevents irregularly shaped (frayed) inflow-side end faces 12 or outflow-side end faces 13 from forming when a honeycomb body is built up. The inflow-side edge area has a width R2 of 1 to 5 mm, the outflow-side edge area 3 has a width R3 of 1 to 5 mm. The sheet metal layer 1 also has at least one connection area 4 , with which the sheet metal layer 1 can later be attached to a casing tube 14 . This connection area 4 with the width R4 is also preferably free of holes 6 . For designs of honeycomb bodies in which the sheet metal layers 1 are fastened to a jacket tube with both ends, a second connection region 5 with a width R5 is also free of holes 6 . If a honeycomb body is to be produced from the sheet metal layer 1 , which has a cavity 7 for receiving a measuring probe 9 , a corresponding cavity 7 is to be seen in the sheet metal layer 1 . According to the invention, this is surrounded by a hole-free edge 8 , which in turn serves to make it easier to process the sheet metal layer 1 and to produce a uniform cavity 7 . The later flow direction S of a fluid which can flow through the honeycomb body is indicated by arrows in the figures.

Fig. 2 shows a perspective view of a honeycomb body according to the invention, in which the expansion of the perforated partial volume T is indicated schematically. The honeycomb body shown as an example is spirally wound from a smooth sheet metal layer 10 and a corrugated sheet metal layer 11 , which are connected to a casing tube 14 in a connection area 4 .

Fig. 3 shows schematically in partially broken side view a catalytic converter with a cavity 7 for receiving a lambda probe 9th An exhaust gas can flow in the flow direction S through the catalytic converter, starting from the upstream end face 12 to the outflow end face 13 . There is a hole-free edge area 2 on the inflow-side end face 12 and a hole-free edge area 3 on the outflow-side face side. In between is the perforated partial volume T which thus extends over almost the entire axial length L of the honeycomb body. The honeycomb body has a cavity 7 , which was produced either after completion of the honeycomb body or previously by suitable placement of cavities in the individual sheet metal layers 10 , 11 . In this cavity 7 is a probe 9, in particular an oxygen measuring probe 9 can be eingebacht. To smooth the edges of the cavity to ensure 7, surrounding the hollow space 7, a hole-free edge 8, in which the sheet metal layers 10, 11 no holes have to 6. The combination of a honeycomb body with holes 6 and a cavity 7 for a measuring probe 9 shown here is particularly advantageous because the holes 6 upstream of the measuring probe 9 allow cross-mixing in the honeycomb body and so the measuring probe 9 takes a representative measured value for the composition of the fluid in the can measure the entire honeycomb body.

The present invention allows most known designs of Honeycomb bodies with reduced use of coating material high effectiveness to achieve the coating's evenness for the treatment of a fluid and there with properties regarding mechanical stability, heat capacity, Thermal conductivity and the like of a honeycomb body tailored to the needs to be able to adapt individual use cases.  

LIST OF REFERENCE NUMBERS

1

sheet metal layer

2

upstream edge area

3

outflow edge area

4

connecting region

5

connecting region

6

hole

7

cavity

8th

hole-free edge

9

lambda probe

10

smooth sheet metal layer

11

corrugated sheet layer

12

upstream end

13

outflow end face

14

casing pipe
L axial length
R2 Width of the upstream edge area
R3 Width of the outflow edge area
R4 Width of the connection area
R5 Width of the connection area
R6 longest extension of a hole
D7 distance between two holes

6

5

flow direction
T partial volume

Claims (16)

1. Metallic honeycomb body with an axial length (L) constructed from Blechla gene ( 1 ; 10 , 11 ), which are structured so that the honeycomb body of a fluid, in particular the exhaust gas of an internal combustion engine, in a direction of flow (S) by one the upstream end face ( 12 ) can flow through to an outflow end face ( 13 ), the sheet metal layers ( 1 ; 10 , 11 ) at least in some areas having a plurality of openings ( 6 ), characterized in that the honeycomb body in a partial volume (T ) of at least 55% of the axial length (L) and at least 20 mm radial expansion in all sheet metal layers ( 1 ; 10 , 11 ) has holes ( 6 ), whereby the following applies:
the holes ( 6 ) each have an area between 1 and 120 mm ² ,
in the partial volume (T), the sheet layer surface is reduced by 10 to 80%, preferably 35 to 60%, through the holes ( 6 ) compared to an unperforated sheet layer,
the partial volume (T) is at a distance (R2, R3) from the end faces ( 12 , 13 ) of the honeycomb body, so that no holes ( 6 ) touch or overlap the end edges of the sheet metal layers. 2. honeycomb body according to claim 1, characterized in that the partial volume (T) more than 60%, preferably more than 90% of the total honeycomb body lumens. 3. honeycomb body according to claim 1 or 2, characterized in that the holes ( 6 ) each have an area of 5 to 60 mm ² . 4. honeycomb body according to claim 1, 2 or 3, characterized in that the holes ( 6 ) have rounded contours. 5. honeycomb body according to claim 1, 2 or 3, characterized in that the holes ( 6 ) are round, oval or elliptical. 6. Honeycomb body according to one of the preceding claims, characterized in that the holes ( 6 ) are made by removing material from a sheet metal layer ( 1 ) that is made of a whole surface. 7. honeycomb body according to one of claims 1 to 5, characterized in that the holes ( 6 ) are already recessed during the manufacture of the sheet metal layer ( 1 ). 8. honeycomb body according to one of the preceding claims, characterized in that the thickness of the sheet metal layers ( 1 ; 10 , 11 ) is 20 to 80 µm, preferably before 40 to 60 µm. 9. honeycomb body according to one of the preceding claims, characterized in that the holes ( 6 ) each have a minimum distance of 0.5 mm, preferably all distances (D7) between the holes are each approximately the same size. 10. honeycomb body according to one of the preceding claims, characterized in that the honeycomb body consists of alternating smooth ( 10 ) and corrugated ( 11 ) or alternating differently corrugated sheet metal layers. 11. honeycomb body according to one of the preceding claims, characterized shows that the honeycomb body has a cell density of 200 to 1000 cpsi (cells per square inch), preferably from 400 to 800 cpsi. 12. Honeycomb body according to one of the preceding claims, characterized in that the sheet metal layers ( 1 ; 10 , 11 ) have additional structures for influencing the flow, in particular transverse structures and / or inversions and / or flow guide surfaces. 13. honeycomb body according to one of the preceding claims, characterized in that the honeycomb body has a cavity ( 7 ) for receiving a sensor, in particular a lambda probe ( 9 ), the cavity ( 7 ) within half of the partial volume (T) or is arranged downstream of the partial volume (T). 14. A honeycomb body according to claim 13, characterized in that adjoining the cavity (7) edges (8) of the sheet-metal layers (1; 10, 11) in a Ab level of 1 to 5 mm to the cavity (7) are free of holes. 15. Honeycomb body according to one of the preceding claims, characterized in that the sheet metal layers ( 1 ; 10 , 11 ) are joined together at least in partial areas on the end faces ( 12 , 13 ), preferably by brazing, in particular in the non-perforated edge areas ( 2 , 3 ). 16. Honeycomb body according to one of the preceding claims, characterized in that the honeycomb body is arranged in a tubular casing ( 14 ), on the connection areas ( 4 , 5 ) of the sheet metal layers ( 1 ; 10 , 11 ) are internally attached, in particular by Brazing, the partial volume (T) not touching the casing tube ( 14 ), that is to say in the connection areas ( 4 , 5 ) of the sheet metal layers ( 1 ; 10 , 11 ) which bear against the casing tube ( 14 ), no holes ( 6 ) are present are.