Filter element for a particulate filter, exhaust gas particulate filter, process for manufacturing a filter element, and use of a coating material

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. 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. A particle filter, a method for producing a filter element, and the use of a coating material for coating a filter element is also provided.

Claims

1. 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 only in parallel, wherein the filter body is provided at least in a part of the flow channels with a mechanically atomized and suctioned coating made of a coating material, which is different from the ceramic material and is made up of orthorhombic crystals, 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.

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

3. The filter element according to claim 2, wherein the coating material is applied to the filter body in such a way that the coating includes fluffy piles of the coating material wherein the fluffy piles are formed during application of the coating material to the filter body by particles of the coating material entangling with one another during the application, such that particles after formation of the coating have a larger grain size than individual particles before the formation of the coating.

4. The filter element according to claim 2, wherein the coating material includes a sheet silicate.

5. The filter element according to claim 4, wherein the sheet silicate is sepiolite or montmorillonite.

6. The filter element according to claim 1, wherein the coating material is applied to the filter body in such a way that the coating includes fluffy piles of the coating material wherein the fluffy piles are formed during application of the coating material to the filter body by particles of the coating material entangling with one another during the application, such that particles after formation of the coating have a larger grain size than individual particles before the formation of the coating.

7. The filter element according to claim 6, wherein the coating material includes a sheet silicate.

8. The filter element according to claim 7, wherein the sheet silicate is sepiolite or montmorillonite.

9. The filter element according to claim 1, wherein the coating material includes a sheet silicate.

10. The filter element according to claim 9, wherein the sheet silicate is sepiolite or montmorillonite.

11. A particle filter, comprising a housing including a fluid inlet and a fluid outlet and a filter element arranged in the housing according to claim 1.

12. A method for producing a filter element, in particular a filter element according to claim 1, wherein the filter element has a porous filter body made of a ceramic material and including a plurality of flow channels extending fluidically only in parallel, wherein the filter body is provided at least in a part of the flow channels with a mechanically atomized and suctioned coating made of a coating material, which is different from the ceramic material and is made up of orthorhombic crystals, 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.

13. The method according to claim 12, wherein the filter body is provided with the coating by generating a fluid flow through the filter body, by which the coating material is suctioned on upstream of the filter body.

Description

BRIEF DESCRIPTION OF THE FIGURE(S)

(1) 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 disclosure. In the single FIGURE,

(2) FIG. 1 shows a schematic sectional view of a particulate filter, in particular for an exhaust system.

DETAILED DESCRIPTION

(3) 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.

(4) 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.

(5) 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.

(6) 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%.

(7) 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.

(8) 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.

(9) 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.

LIST OF REFERENCE NUMBERS

(10) 1 particle filter 2 housing 3 filter element 4 filter body 5 jacket surface 6 spacer 7 flow channel 8 longitudinal center axis 9 surface 10 surface 11 inlet side 12 outlet side 13 fluid inlet 14 fluid outlet 15 arrow 16 first closure plug 17 second closure plug 18 first flow channel 19 second flow channel 20 arrow 21 coating 22 catalyst coating