SUBSTRATE FOR AN EXHAUST GAS TREATMENT UNIT

Abstract

A substrate for an exhaust gas treatment unit, particularly for an exhaust system of an internal combustion engine, includes a substrate body (18) elongated in the substrate longitudinal direction (S). The substrate body (18) is flattened in a flattening direction (A) essentially at right angles to the substrate longitudinal direction (S). A plurality of cells (24), which extend essentially in the substrate longitudinal direction (S) and provide flow ducts, are formed in the substrate body (18). The cells (24) are defined by cell walls (20, 22), which extend essentially in the substrate longitudinal direction (S). The cell walls (20, 22) are disposed at an angle in relation to the flattening direction (A).

Claims

1. An exhaust gas treatment unit substrate comprising a substrate body elongated in a substrate longitudinal direction, wherein: the substrate body is flattened in a flattening direction essentially at right angles to the substrate longitudinal direction; the substrate body comprises a plurality of cells extending essentially in the substrate longitudinal direction; the cells are defined by cell walls and provide flow ducts, which extend essentially in the substrate longitudinal direction; and the cell walls are disposed at an angle in relation to the flattening direction.

2. An exhaust gas treatment unit substrate in accordance with claim 1, wherein the cell walls comprise: first cell walls arranged parallel to one another and at spaced locations from one another; and second cell walls arranged parallel to one another and at spaced locations from one another, wherein the first cell walls are disposed at an angle in relation to the second cell walls such that the cells are each defined by two first cell walls and by two second cell walls.

3. An exhaust gas treatment unit substrate in accordance with claim 2, wherein the first cell walls are disposed at an angle of about 90 in relation to the second cell walls.

4. An exhaust gas treatment unit substrate in accordance with claim 2, wherein the mutual spacing from one another of directly adjacent first cell walls corresponds essentially to the mutual spacing from one another of directly adjacent second cell walls.

5. An exhaust gas treatment unit substrate in accordance with claim 2, wherein: cells adjacent to one another form cell lines; and the cells of each of the cell lines are defined by two identical first cell walls or by the two identical second cell walls.

6. An exhaust gas treatment unit substrate in accordance with claim 2, wherein: the first cell walls and the second cell walls form a grid-shaped cell wall structure; or the first cell walls and the second cell walls are essentially unbent; or the first cell walls and the second cell walls form a grid-shaped cell wall structure, and the first cell walls and the second cell walls are essentially unbent.

7. An exhaust gas treatment unit substrate in accordance with claim 1, wherein: the cells have an essentially rectangular or square cross-sectional contour; or the cell walls are disposed at an angle in a range from 40 to 50 in relation to the flattening direction; or the cells have an essentially rectangular or square cross-sectional contour, and the cell walls are disposed at an angle in a range from 40 to 50 in relation to the flattening direction.

8. An exhaust gas treatment unit substrate in accordance with claim 1, wherein: the substrate body is configured with an essentially mirror-symmetrical outer circumferential contour in relation to a first longitudinal central plane, which is extended in the flattening direction and in the substrate longitudinal direction; or the substrate body is configured with an essentially mirror-symmetrical outer circumferential contour in relation to a second longitudinal central plane, which is extended at right angles to the flattening direction and in the substrate longitudinal direction; or the substrate body is configured with an essentially mirror-symmetrical outer circumferential contour in relation to a first longitudinal central plane, which is extended in the flattening direction and in the substrate longitudinal direction, and the substrate body is configured with an essentially mirror-symmetrical outer circumferential contour in relation to a second longitudinal central plane, which is extended at right angles to the flattening direction and in the substrate longitudinal direction.

9. An exhaust gas treatment unit substrate in accordance with claim 1, wherein: the substrate body has a flattened, round, or an elliptical outer circumferential contour; or the substrate body has an essentially cylindrical configuration in relation to the substrate longitudinal direction; or the substrate body has a flattened, round, or an elliptical outer circumferential contour, and the substrate body has an essentially cylindrical configuration in relation to the substrate longitudinal direction.

10. An exhaust gas treatment unit substrate in accordance with claim 1, wherein: the substrate body is comprised of ceramic material; or the cell walls are coated with exhaust gas treatment material; or the substrate body is comprised of ceramic material, and the cell walls are coated with exhaust gas treatment material.

11. An exhaust gas treatment unit comprising: a housing with a tubular circumferential wall, which encloses a housing interior, and a substrate arranged in the housing interior, the substrate comprising a substrate body elongated in a substrate longitudinal direction, wherein: the substrate body is flattened in a flattening direction essentially at right angles to the substrate longitudinal direction; the substrate body comprises a plurality of cells extending essentially in the substrate longitudinal direction; the cells are defined by cell walls and provide flow ducts, which extend essentially in the substrate longitudinal direction; and the cell walls are disposed at an angle in relation to the flattening direction.

12. An exhaust gas treatment unit in accordance with claim 11, further comprising a layer of support material, wherein the substrate, arranged in the housing interior, is enclosed by at least one layer of support material and is configured to support the substrate in relation to the circumferential wall.

13. An exhaust gas treatment unit in accordance with claim 11, wherein: the circumferential wall is flattened in the flattening direction; or the circumferential wall has a flattened, round, or essentially elliptical outer circumferential contour; or the circumferential wall is flattened in the flattening direction, and the circumferential wall has a flattened, round, or essentially elliptical outer circumferential contour

14. An exhaust gas treatment unit substrate in accordance with claim 11, wherein the cell walls comprise: first cell walls arranged parallel to one another and at spaced locations from one another; and second cell walls arranged parallel to one another and at spaced locations from one another, wherein the first cell walls are disposed at an angle in relation to the second cell walls such that the cells are each defined by two first cell walls and by two second cell walls.

15. An exhaust gas treatment unit in accordance with claim 14, wherein the first cell walls are disposed at an angle of about 90 in relation to the second cell walls.

16. An exhaust gas treatment unit in accordance with claim 14, wherein the mutual spacing from one another of directly adjacent first cell walls corresponds essentially to the mutual spacing from one another of directly adjacent second cell walls.

17. An exhaust gas treatment unit in accordance with claim 14, wherein: cells adjacent to one another form cell lines; and the cells of each of the cell lines are defined by two identical first cell walls or by the two identical second cell walls.

18. An exhaust gas treatment unit in accordance with claim 14, wherein: the first cell walls and the second cell walls form a grid-shaped cell wall structure; or the first cell walls and the second cell walls are essentially unbent; or the first cell walls and the second cell walls form a grid-shaped cell wall structure, and the first cell walls and the second cell walls are essentially unbent.

19. An exhaust gas treatment unit in accordance with claim 14, wherein: the cells have an essentially rectangular or square cross-sectional contour; or the cell walls are disposed at an angle in a range from 40 to 50 in relation to the flattening direction; or the cells have an essentially rectangular or square cross-sectional contour, and the cell walls are disposed at an angle in a range from 40 to 50 in relation to the flattening direction.

20. An exhaust gas treatment unit in accordance with claim 11, wherein: the substrate body is configured with an essentially mirror-symmetrical outer circumferential contour in relation to a first longitudinal central plane, which is extended in the flattening direction and in the substrate longitudinal direction; or the substrate body is configured with an essentially mirror-symmetrical outer circumferential contour in relation to a second longitudinal central plane, which is extended at right angles to the flattening direction and in the substrate longitudinal direction; or the substrate body is configured with an essentially mirror-symmetrical outer circumferential contour in relation to a first longitudinal central plane, which is extended in the flattening direction and in the substrate longitudinal direction, and the substrate body is configured with an essentially mirror-symmetrical outer circumferential contour in relation to a second longitudinal central plane, which is extended at right angles to the flattening direction and in the substrate longitudinal direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In the drawings:

[0020] The only FIGURE is a cross-sectional view of an exhaust gas treatment unit with a substrate accommodated in a tubular housing.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0021] Referring to the drawings, an exhaust gas treatment unit, for example, a catalytic converter unit, for an exhaust system of an internal combustion engine in a vehicle is generally designated by 10 in FIG. 1. The exhaust gas treatment unit 10 comprises a tubular housing 12 with a longitudinal central axis L at right angles to the drawing plane of FIG. 1. The housing 12 comprises a circumferential wall 14, which is made, for example, of sheet metal material and which is flattened in a flattening direction A and thus has a flattened, round, for example, elliptical outer circumferential contour in the example shown.

[0022] A substrate generally designated by 16 is arranged in the interior of the housing 12, which interior is enclosed by the circumferential wall 14. The substrate 16 has a substrate body 18, which is made, for example, of ceramic material. A plurality of cells 24, which are defined by first cell walls 20 and by second cell walls 22, which extend in a substrate longitudinal direction S, which corresponds essentially to the direction of extension in the longitudinal central axis L in the example shown, are formed in the substrate body 18. The first cell walls 20 and the second cell walls 22 are disposed at an angle in relation to the flattening direction A and have an angle of about 45 to this flattening direction in the example shown. In this case, in the view of FIG. 1, the first cell walls 20 extend obliquely from the left bottom to the right top or vice versa, while the second cell walls 22 extend obliquely from the right bottom to the left top or vice versa. Since both the first cell walls 20 and the second cell walls 22 are disposed at an angle of about 45 in relation to the flattening direction, the first cell walls 20 and the second cell walls 22 are approximately at right angles to one another. Since, furthermore, the first cell walls 20 and also the second cell walls 22 extend each essentially without interruption between two outer circumferential areas of the substrate body 18, a grid-shaped structure of the cell walls 20, 22 is obtained, in which the cells 24 defined by two first cell walls 20 directly adjacent to one another and two second cell walls 22 directly adjacent to one another have a rectangular cross-sectional contour. Since, furthermore, the mutual spacing of all first cell walls 20 directly adjacent to one another corresponds in an especially preferred embodiment essentially to the mutual spacing of all second cell walls 22 directly adjacent to one another, the cells 24 have a square cross-sectional contour as well.

[0023] First cell lines, which are illustrated by a line L.sub.1 in FIG. 1, are formed by cells 24 adjacent to one another or following one another in the direction of the line L.sub.1 between the first cell walls 20, which are parallel to one another and are disposed at an angle in relation to the flattening direction A. Equally, second cells lines, which are illustrated by a line L2 in FIG. 1, are formed by cells 24 adjacent to one another or following one another in the direction of the line L2 between the second cell walls 22, which are parallel to one another and are disposed at an angle in relation to the flattening direction A. All cells 24 in a particular first cell line L.sub.1 are defined by the two identical first cell walls 20 and all cells 24 in a particular second cell line L2 are defined by the two identical second cell walls 22.

[0024] The substrate 16 has a flattened, round, for example, elliptical outer circumferential contour of the circumferential wall 14 in adaptation to the cross-sectional contour of the circumferential wall 14. In this case, the substrate 16 has an especially mirror-symmetrical outer circumferential contour, which is symmetrical to a first longitudinal central plane that extends essentially in the flattening direction A and in the direction of the longitudinal central axis L. This first longitudinal central plane E.sub.1 intersects the substrate 16 in the two areas 26 with maximum radius of curvature of the outer circumferential contour, which areas are diametrically opposed to each other. The substrate 16 has an especially mirror-symmetrical configuration, which is also symmetrical to a second longitudinal central plane E.sub.2, which is at right angles to the first longitudinal central plane E.sub.1 and also contains the longitudinal central axis L. The second longitudinal central plane E.sub.2 intersects the outer circumference of the substrate 16 in areas 28 with minimal radius of curvature of the outer circumferential contour of the substrate 16, which areas 28 are diametrically opposed to each other.

[0025] When the substrate 16 is inserted into the housing 12 or into the circumferential wall 14 of same, at first the substrate 16 is wrapped with at least one layer of support material 30, for example, fiber mat or the like. The thus wrapped substrate 16 is then inserted into the housing 12, for example, via an insertion funnel. In this case, the layer of support material 30 is compressed, so that the substrate 16 is held by the compressed layer of support material 30 in a defined position in the interior of the housing 12. In the course of this insertion motion, the greatest surface pressure is exerted onto the substrate 16 in transition areas 32 between the areas 28 with minimal radius of curvature and the areas 26 with maximum radius of curvature. Since the cell walls 20, 22 extend at an angle of about 45 in relation to the flattening direction A, one of the two types of cell walls 20, 22 each extends in each of the transition areas 32, in which the outer circumferential contour of the substrate 16 has an average radius of curvature, approximately at right angles to the force F acting from outside on the substrate 16 in these areas. The result is that the forces acting on the substrate 16 in these high-load areas can be absorbed in the respective cell walls 20, 22 which extend approximately in the force introduction direction, without a significant deformation of the substrate 16 being generated, since the substrate 16 also essentially has its maximum stiffness in the direction of the force introduction. The risk that damage, for example, cracks in the substrate body 18 is brought about by such loads is thus reduced significantly.

[0026] Finally, it should be pointed out that when the the substrate body 18 is used in a catalytic converter unit, the substrate body 18 can be coated with catalytically active material on its cell walls 20, 22 defining the cells 24. The exhaust gas flowing through the cells 24 can thus interact with the catalytic material in the area of a comparatively large surface in the interior of the substrate body 18 for carrying out the catalytic reaction, so that such a catalytic converter may be effective, for example, as an oxidation catalytic converter or as a SCR catalytic converter.

[0027] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.