FILTER ELEMENT FOR A PARTICULATE FILTER, AND EXHAUST GAS PARTICULATE FILTER

Abstract

A filter element for a particle filter having a porous filter body made of a ceramic material and including a plurality of flow channels extending fluidically in parallel. It is provided that the filter body is provided at least in a part of the flow channels with a coating made of a coating material, which is different from the ceramic material and is made up of orthorhombic crystals, namely sepiolite. The coating forms an outer layer of the filter element.

Claims

1-4. (canceled)

5. A filter element for a particle filter, comprising: a porous filter body made of a ceramic material and including a plurality of flow channels extending fluidically in parallel, wherein the filter body is provided at least in a part of the flow channels with a mechanically applied coating made of a coating material, which is different from the ceramic material and is made up of orthorhombic crystals, namely sepiolite, wherein the coating forms an outer layer of the filter element, the coating material has a specific surface area of at least 200 m.sup.2/g, and an amount of material of the coating material applied to the filter body in relation to a total volume of the filter body is 2 g/l to 5 g/l.

6. The filter element according to claim 5, wherein the coating material includes particles having a grain size of at least 1 μm to at most 20 μm.

7. The filter element according to claim 5, wherein the coating material is applied to the filter body in such a way that the coating includes fluffy piles of the coating material.

8. A particle filter, having a housing including a fluid inlet and a fluid outlet and a filter element according to claim 5 arranged in the housing.

9. The filter element according to claim 6, wherein the coating material is applied to the filter body in such a way that the coating includes fluffy piles of the coating material.

10. A particle filter, having a housing including a fluid inlet and a fluid outlet and a filter element according to claim 6 arranged in the housing.

11. A particle filter, having a housing including a fluid inlet and a fluid outlet and a filter element according to claim 7 arranged in the housing.

Description

[0045] In the following, the invention will be explained in greater detail with reference to the exemplary embodiments depicted in the drawings, without this restricting the invention. In the single figure,

[0046] Figure shows a schematic sectional view of a particulate filter, in particular for an exhaust system.

[0047] The figure shows a schematic longitudinal sectional illustration of a particle filter 1, for example for an exhaust system. The particle filter 1 has a housing 2, which is only indicated here. The housing 2 can also be referred to as “canning” and is preferably made of metal. In the housing 2, a filter element 3 is arranged, which includes a porous filter body 4 made of a ceramic material. In the exemplary embodiment shown here, the filter body 3 has a jacket surface 5 which is implemented, for example, in the form of a coating and/or by corresponding processing of the filter body 3. For example, the jacket surface 5 is fluid-tight, that is, it closes the filter body 3 in the radial direction towards the outside. The filter body 3 is preferably arranged in the housing 2 in such a way that its jacket surface 5 is arranged spaced apart from the housing 2, for example by spacers 6. Alternatively, however, an embodiment of the particle filter 1 can also be implemented in which the jacket surface 5 of the filter element 3 presses against an inner circumferential surface of the housing 2, in particular continuously in the circumferential direction.

[0048] In the filter body 4, a plurality of flow channels 7 extending fluidically in parallel are formed, of which only a few are identified here by way of example. It can be seen that the filter element 3 is cylindrical, in particular circular cylindrical, with respect to its longitudinal center axis 8. However, other embodiments of the filter element 3, for example a conical shape, can also be implemented. The end face of the filter element 3 has two surfaces 9 and 10, which are connected to one another via the jacket surface 5. In the case of the cylindrical or circular cylindrical embodiment of the filter element 3, the surfaces 9 and 10 have the same surface area or at least a similar surface area.

[0049] The surface 9 is on an inlet side 11 and the surface 10 is on an outlet side 12 of the filter element 3. The inlet side 11 of the filter element 3 faces toward a fluid inlet 13 of the housing 2, whereas the outlet side 12 faces toward a fluid outlet 14 of the housing 2. A direction of flow of the exhaust gas through the particle filter 1 or the filter element 3 is indicated by the arrow 15. The flow channels 7 that are present in the filter element 3 or the filter element 4 are provided with first closure plugs 16 and second closure plugs 17, a few of which are each identified here by way of example. The first closure plugs 16 are in a first plug plane and the second closure plugs 17 are in a second plug plane.

[0050] The flow channels 7 can be divided into first flow channels and second flow channels 19, only a few of which are each identified by way of example. The flow channels 7 are preferably composed only of first flow channels 18 and second flow channels 19. There are preferably as many first flow channels 18 as there are second flow channels 19 or vice versa in the filter body 4. However, it can also be provided that the number of first flow channels 18 differs from the number of second flow channels 19, but preferably only by at most 10%, at most 7.5%, at most 5%, at most 2.5%, or at most 1%.

[0051] One of the first closure plugs 16, but none of the second closure plugs 17, is arranged in each of the first flow channels 18. In contrast, none of the first closure plugs 16 but one of the second closure plugs 17 is arranged in each of the second flow channels 19. This means that the first flow channels 18 are closed on the inlet side and open on the outlet side, whereas the second flow channels 19 are open on the inlet side and closed on the outlet side. A flow through the filter element 3 resulting therefrom is indicated by the arrows 20.

[0052] It is now provided that the filter body 4 is provided with a coating 21, at least in some of the flow channels 7, which consists of a coating material that is different from a ceramic material of the filter body 4. The coating material includes orthorhombic crystals and to this extent consists at least partially of a material, in particular of a mineral material, which contains such orthorhombic crystals. With the aid of this coating 21, the filtration performance of the particle filter 1 is significantly improved with low counter pressure or low pressure loss. Provision can be made for the coating 21 to be applied to the filter body 4 before the flow channels 7 are closed using the closure plugs 16 and 17. This enables a particularly simple production of the particle filter 1. However, it can also be provided that the coating 21 is only applied to the filter body 4 after the flow channels 7 have been closed using the plugs 16 and 17. As a result, the coating 21 is formed only in those flow channels 7 which are closed using the closure plugs 17, that is to say in which there are no closure plugs 16. In other words, the coating 21 is only formed in the second flow channels 19, but not in the first flow channels 18.

[0053] The filter body 4 is particularly preferably provided with a catalyst coating 22 at least in the flow channels 7 before the coating 21 is applied. The catalyst coating is a catalytically active coating, in particular a three-way coating, so that the filter 1 there works both as a particle filter and also as a three-way catalyst. After the catalyst coating 22 has been applied, the coating 21 is applied, namely according to the above statements. Accordingly, a filter body 4 results, for example, in which the catalyst coating 22 is only partially provided with the coating 21. A part of the catalyst coating 22 is thus provided with the coating 21, whereas another part of the catalyst coating 22 is free of coating. The catalyst coating 22 is preferably provided with the coating 21 only in the second flow channels 19, whereas it is present without a coating in the first flow channels 18.

[0054] In any case—that is, both in an embodiment with a catalyst coating 24 and also in an embodiment without this—the coating 21 represents an outer layer of the filter element, in particular seen in section. After the filter element 3 and/or the particle filter 1 has been completely manufactured, the coating 21 thus delimits the filter element 3 in the direction of the fluid and therefore closes it off in this direction. In this respect, no further layer follows the coating 21 when viewed in section. Rather, when fluid flows through the filter element 3, in particular during operation of the particle filter 1, the fluid flows directly onto and/or over the coating 21 and ultimately flows through it in the direction of the filter body 4. The fluid thus penetrates through the coating 21 into the filter element 3, namely in particular from the flow channels 7 or at least a part of the flow channels 7.

LIST OF REFERENCE NUMBERS

[0055] 1 particle filter

[0056] 2 housing

[0057] 3 filter element

[0058] 4 filter body

[0059] 5 jacket surface

[0060] 6 spacer

[0061] 7 flow channel

[0062] 8 longitudinal center axis

[0063] 9 surface

[0064] 10 surface

[0065] 11 inlet side

[0066] 12 outlet side

[0067] 13 fluid inlet

[0068] 14 fluid outlet

[0069] 15 arrow

[0070] 16 first closure plug

[0071] 17 second closure plug

[0072] 18 first flow channel

[0073] 19 second flow channel

[0074] 20 arrow

[0075] 21 coating

[0076] 22 catalyst coating