DE20309398U1 - Compact assembly comprising honeycomb in conical casing for use in exhaust gas purification systems, includes recessed sensor - Google Patents

Abstract

A sensor (2) is constructed to pass through an opening (7) in the casing, into a recess (11) within the honeycomb (1) interior. The sensor, partially inside the cone and partially outside it, does not project forward beyond the front plane (12) of the cone. The sensor axis is normal to the cone surface and the edge of the recess opening is spaced from the minor end face (5) of the cone. The spacing is 10%, preferably 20%, especially 40% of the axial length of the cone. The region bordering the cavity forms a honeycomb structure and is made of ceramic or metal. It is made by winding, and/or stacking of structured metallic layers which are twisted. The cone may terminate each end of a cylindrical honeycomb, the minor ends facing outward.

Description

17 June 2003

Emitec Society for Emissions Technology- E81180KA/HN

nologie mbH

Conical honeycomb body with sensor and corresponding exhaust aftertreatment system

The subject matter of the invention is a conical honeycomb body with a measuring sensor, as well as an exhaust gas aftertreatment system with at least one such conical honeycomb body.

In automobile construction, honeycomb bodies are often used as carrier bodies for catalyst material to convert at least parts of the automobile's exhaust gas. These honeycomb bodies have a large number of cavities, for example channels, through which a fluid can at least flow. Honeycomb bodies are made of ceramic or metallic layers, or are known as extruded honeycomb bodies and, in addition to catalytic conversion, can also be used as filters to filter out particles in the exhaust gas of an automobile, for example to filter out soot particles, especially in the exhaust gas of automobiles with diesel engines.

There are two typical designs for metallic honeycomb bodies. An early design, for which DE 29 02 779 A1 shows typical examples, is the spiral design, in which essentially a smooth and a corrugated sheet metal layer are placed on top of each other and wound up in a spiral shape. In another design, the honeycomb body is constructed from a large number of alternating smooth and corrugated or differently corrugated sheet metal layers, with the sheet metal layers initially forming one or more stacks that are intertwined with each other. The ends of all sheet metal layers are placed on the outside and can be connected to a housing or casing tube, creating numerous connections that increase the durability of the honeycomb body. Typical examples of these designs are in the

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Emitec Company for Emissions Technology mbH

17 June 2003 E8118OKA/HN

EP 0 245 737 Bl or WO 90/03220. It has also long been known to equip the sheet metal layers with additional structures in order to influence the flow and/or to achieve cross-mixing between the individual flow channels. Typical examples of such designs are WO 91/01178, WO 91/01807 and WO 90/08249. Finally, there are also honeycomb bodies in a conical design, possibly also with further additional structures to influence the flow. Such honeycomb bodies are known, for example, from WO 93/20339 and WO 97/49905. In addition, it is also known to leave a recess in a honeycomb body for a sensor, in particular for accommodating a lambda probe. An example of this is described in DE 88 16 154 Ul and WO 02/075126.

Space problems often arise when constructing an exhaust aftertreatment system in an automobile, since the use of measuring sensors, such as lambda sensors, in a cylindrical honeycomb body increases the radial clearance required for installation due to the protruding measuring sensors.

Based on this, it is the object of the invention to propose a honeycomb body and an exhaust gas aftertreatment system with at least one measuring sensor, the radial clearance required for installation of which is not increased by the measuring sensor.

This object is achieved by a honeycomb body with the features of claim 1 and an exhaust gas aftertreatment system with the features of claim 9. Advantageous embodiments and further developments are the subject of the respective dependent claims.

The honeycomb body according to the invention comprises a longitudinal axis, a jacket tube conical with respect to this, and has between a first end face and a

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17 June 2003 Emitec Gesellschaft ffir Emissionstechnologie mbH E81180 KA/HN

second end face has cavities through which a fluid can flow. The honeycomb body according to the invention is characterized in that a measuring sensor is formed which extends through an opening in the casing tube into a recess (11) in the interior of the honeycomb body.
5

According to an advantageous development of the honeycomb body according to the invention, the measuring sensor has an outer portion outside the jacket tube and an inner portion inside the jacket tube, wherein the projection of the outer portion of the at least one measuring sensor onto a plane that includes the first end face of the honeycomb body lies within the projection of the second end face of the honeycomb body onto this plane.

This advantageously allows the use of measuring sensors in honeycomb bodies without the radial clearance required for installation being increased by the measuring sensor. The radial clearance is understood to be the maximum radius required for installing the honeycomb body. In the case of a honeycomb body with a conical shape, this is the radius of the larger second end face of the honeycomb body. A honeycomb body according to the invention is therefore characterized precisely by the fact that the measuring sensor does not protrude beyond the outer edge of the larger second end face of the conical honeycomb body.

Any measuring sensor that delivers a measured value proportional to at least one characteristic of the fluid or the exhaust gas is possible and according to the invention, in particular lambda sensors, HC sensors, temperature sensors, nitrogen oxide sensors, etc.

According to an advantageous development of the honeycomb body according to the invention, the measuring sensor is designed essentially parallel to a surface normal of the jacket tube.

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17 June 2003 Eraitec Society for Emissions Technology mbH E81180 KA/HN

The invention is expressly not limited to the sensor being perpendicular to the casing tube; rather, a flat or steep installation of the sensor is also possible. However, a vertical installation offers the advantage that, with the same length of the sensor, the inner part cuts through a larger number of channels. This requires averaging over a larger number of channels and can therefore, in the case of, for example, layered flow at the edge of the honeycomb body, lead to a more representative measurement result than, for example, a flatter angle between the axis of the sensor and casing tube.

According to a further advantageous embodiment of the honeycomb body according to the invention, the cutting surface of the inner portion of the measuring sensor with a plane within the honeycomb body, which has the longitudinal axis of the honeycomb body as a surface normal and which the measuring sensor at least intersects, lies within a circular ring whose inner radius is at least 40% of the radius of the honeycomb body in this plane, preferably at least 50%, particularly preferably at least 60%.

According to a further advantageous embodiment of the honeycomb body, the edge of the opening facing the first end face is formed at a distance from the first end face.

The design of the sensor at a minimum distance from the front side of the honeycomb body protects the sensor from any potentially harmful effects of the exhaust gas, for example from water hammer, as this is effectively prevented by the impact of the exhaust gas on the first front side of the honeycomb body. This is due to the fact that the honeycomb body itself quickly heats up above the boiling point of water due to the hot exhaust gas before the starting temperature of the catalytic conversion is reached, so that it does not cause

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17 June 2003 Eraitec Society for Emissions Technology mbH E81180 KA/HN

impact of water droplets on the sensor. In this context, it is advantageous that the honeycomb body has an axial length and the distance is at least 10%, preferably at least 20%, particularly preferably at least 40% of the axial length.
5

According to a further advantageous embodiment of the honeycomb body, the boundaries of the cavities form a honeycomb structure which is made of ceramic material.

According to a further advantageous embodiment of the honeycomb body, the boundaries of the cavities form a honeycomb structure which is made of metallic layers.

A further advantageous embodiment of the honeycomb body is characterized by the fact that the honeycomb structure

a) by winding at least one at least partially structured metallic layer or at least one substantially smooth and at least one at least partially structured metallic layer or

b) by stacking a plurality of substantially smooth and at least partially structured metallic layers and then twisting at least one stack

is trained.

According to a further aspect of the inventive concept, an exhaust gas aftertreatment system is proposed which comprises at least one conical honeycomb body according to the invention. It is particularly advantageous in this context if the exhaust gas aftertreatment system comprises two conical honeycomb bodies

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17 June 2003 Emitec Society for Emissions Technology mbH E81180 KA/HN

and a cylindrical honeycomb body lying between them, wherein at least one of the conical honeycomb bodies is one according to the invention.

A large conversion volume is often realized in a cylindrical honeycomb body, in front of which a conical honeycomb body is formed to slow down the flow, which leads to an increase in the time available for catalytic conversion. Often another conical honeycomb body is connected to the cylindrical honeycomb body, which leads to a further reduction in the pipe radius. In such systems, the radial clearance is determined by the cylindrical honeycomb body. In order not to increase the required radial clearance, it is therefore advantageous to form at least one measuring sensor in one or both conical honeycomb bodies, i.e. to form honeycomb bodies according to the invention before and/or after the cylindrical honeycomb body. These allow the formation of one or more measuring sensors without increasing the radial clearance required for installation.

Further advantages and embodiments are explained in more detail with reference to the drawing, without the invention being limited to these. They show:

Fig. 1 shows an embodiment of a honeycomb body according to the invention in longitudinal section and

Fig. 2 shows an embodiment of an exhaust gas aftertreatment system according to the invention in longitudinal section.
25

Fig. 1 shows a honeycomb body 1 according to the invention with a measuring sensor 2. The honeycomb body 1 has a jacket tube 3 which is conical with respect to the longitudinal axis 4 of the honeycomb body 1. The honeycomb body 1 has a first end face 5 and a

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17 June 2003 Emitec Society for Emissions Technology mbH E81180 KA/HN

second end face 6, wherein the second end face 6 has a larger cross-sectional area than the first end face 5.

The interior of the honeycomb body 1 is traversed by cavities (not shown), for example channels, through which a fluid can flow. These cavities are formed by a honeycomb structure, which can be made of ceramic and/or metal. In particular, when constructing metallic honeycomb structures, it is possible to construct them by winding or stacking and twisting a plurality of stacks, each made of at least partially structured or at least partially structured and essentially smooth metallic layers, without the construction of metallic honeycomb bodies being limited to this. In particular, the honeycomb structure can be constructed layer by layer from ceramic and/or metallic and/or other material. In addition to sheet metal layers, in particular with micro and macro structures, and holes, the dimensions of which can be larger or smaller than the structural repeat length of the at least partially structured layers, metallic layers as defined above also include a material through which a fluid can flow, such as a metal fiber material.

The measuring sensor 2 is introduced into the honeycomb body 1 through an opening 7 in the casing tube 3, the edge of which is formed by the flange 8. The flange 8 serves to fasten the measuring sensor 2, but other types of fastening are also possible and in accordance with the invention. The measuring sensor 2 has an inner part 9 and an outer part 10, which are located inside and outside the casing tube.

The separation of these two parts 9, 10 is indicated in Fig. 1 by a dashed line in the area of the jacket tube 3. The inner part 9 extends into a recess 11 of the honeycomb body 2 so that it can detect at least one parameter in the fluid flowing through the honeycomb body 2. The outer part 10 of the sensor 2 is designed according to the invention such that the sensor 2

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Emitec Company for Emissions Technology mbH

June 17, 2003 E81180 &Kgr;&Agr;/&EEgr;&Ngr;

does not protrude beyond the honeycomb body 1, it is thus designed such that the projection of the outer portion 9 of the measuring sensor 2 onto a plane 12, which includes the first end face 5 of the honeycomb body 1, lies within the projection of the second end face 6 of the honeycomb body 1 onto this plane 12. The projection of the second end face 6 is marked by the dashed lines 13. According to the invention, the measuring sensor 2 is therefore located within these dashed lines 13.

In the present embodiment, the measuring sensor 2 is designed parallel to a surface normal of the casing tube 3, but a steeper or flatter installation of the measuring sensor 2 is just as possible and in accordance with the invention. Furthermore, in the present example, the opening 7 is designed such that the edge of the opening 7 facing the first end face 5 is designed at a distance from the first end face 5. However, the design of a measuring sensor 2 within the first 5 and/or second end face 6 is also possible.

Figure 2 shows an exhaust gas aftertreatment system 14 which consists of a cylindrical honeycomb body 15 and two conical honeycomb bodies 1 according to the invention. The respective diameters of the end faces 6 of the conical honeycomb bodies 1 are adapted to the diameter of the end faces 16 of the cylindrical honeycomb body 15. In each of the conical honeycomb bodies 1, measuring sensors 2 are formed which, according to the invention, lie within the dashed lines 13. This means that the projection of the measuring sensors onto a plane which includes the first end faces 5 of the conical honeycomb bodies 1 according to the invention lies within the projection of the second end faces 6 of the conical honeycomb bodies 1 onto this plane, whereby the exhaust gas aftertreatment system 14 can be installed in an automobile without an increased radial clearance despite the measuring sensors 2. The design of the measuring sensors 2 is only shown schematically in Figure 2 and is essentially as shown in Figure 1. Reference is also made to Figure 1 for further details.

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· · t

17 June 2003 Emitec Gesellschaft flir Emissionstechnologie mbH E81180 KA/HN

A honeycomb body 1 according to the invention allows the formation of measuring sensors 2 without an increased radial clearance being necessary when installing the honeycomb body 1.

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17 June 2003 Emitec Society for Emissions Technology mbH E81180 KA/HN

List of reference symbols

1 conical honeycomb body

2 Sensor 3 Jacket pipe 4 Longitudinal axis 5 first front side 6 second front side 7 opening 8th flange 9 inner part 10 outer part 11 Recess 12 level 13 line 14 Exhaust aftertreatment system 15 cylindrical honeycomb body 16 Front side

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Claims (11)

1. Honeycomb body ( 1 ) with a longitudinal axis ( 4 ), a jacket tube ( 3 ) which is conical with respect to this and which has cavities through which a fluid can flow between a first end face ( 5 ) and a second end face ( 6 ), characterized in that a measuring sensor ( 2 ) is formed which extends through an opening ( 7 ) in the jacket tube ( 2 ) into a recess ( 11 ) in the interior of the honeycomb body ( 1 ). 2. Honeycomb body ( 1 ) according to claim 1, characterized in that the measuring sensor ( 2 ) has an outer portion ( 10 ) outside the casing tube ( 3 ) and an inner portion ( 9 ) inside the casing tube ( 3 ), wherein the projection of the outer portion ( 10 ) of the at least one measuring sensor ( 2 ) onto a plane ( 12 ) which includes the first end face ( 5 ) of the honeycomb body ( 1 ) lies within the projection ( 13 ) of the second end face ( 6 ) of the honeycomb body ( 1 ) onto this plane ( 12 ). 3. Honeycomb body ( 1 ) according to claim 1 or 2, characterized in that the measuring sensor ( 2 ) is designed substantially parallel to a surface normal of the casing tube ( 3 ). 4. Honeycomb body ( 1 ) according to one of the preceding claims, characterized in that the cutting surface of the inner portion ( 9 ) of the measuring sensor ( 2 ) with a plane within the honeycomb body ( 1 ), which has the longitudinal axis ( 4 ) of the honeycomb body ( 1 ) as a surface normal and which the measuring sensor ( 2 ) at least intersects, lies within a circular ring whose inner radius is at least 40% of the radius of the honeycomb body ( 1 ) in this plane, preferably at least 50%, particularly preferably at least 60%. 5. Honeycomb body ( 1 ) according to one of the preceding claims, characterized in that the edge of the opening ( 7 ) facing the first end face (S) is formed at a distance from the first end face ( 5 ). 6. Honeycomb body ( 1 ) according to claim 5, characterized in that the honeycomb body ( 1 ) has an axial length and the distance is at least 10%, preferably at least 20%, particularly preferably at least 40% of the axial length. 7. Honeycomb body ( 1 ) according to one of the preceding claims, characterized in that the boundaries of the cavities form a honeycomb structure which is made of ceramic material. 8. Honeycomb body ( 1 ) according to one of claims 1 to 6, characterized in that the boundaries of the cavities form a honeycomb structure which is made of metallic layers. 9. Honeycomb body ( 1 ) according to claim 8, characterized in that the honeycomb structure a) by winding at least one at least partially structured metallic layer or at least one substantially smooth and at least one at least partially structured metallic layer or b) by stacking a plurality of substantially smooth and at least partially structured metallic layers and then twisting at least one stack is trained. 10. Exhaust aftertreatment system ( 14 ) with at least one conical honeycomb body ( 1 ) according to one of claims 1 to 9. 11. Exhaust aftertreatment system ( 14 ) according to claim 10, in which two conical honeycomb bodies ( 1 ) and a cylindrical honeycomb body ( 14 ) lying between them are formed, wherein at least one of the conical honeycomb bodies ( 1 ) is a honeycomb body according to one of claims 1 to 8.