Particle trap with coated fibre layer

Translation of description of equivalent WO 2004050219 A1

p0001Particulate trap with coated fiber layer

p0002The invention relates to a high temperature-resistant fiber layer for a particulate trap for purifying exhaust gases from mobile internal combustion engine n or a particle trap itself.

p0003Regarding the purification of exhaust gases, particularly of diesel engines, as can be hydrocarbons (HC) and carbon monoxide (CO) oxidized in the exhaust gas in a known manner by being brought into contact, for example, with components, which optionally have a catalytically active surface. The reduction of nitrogen oxides (NO_x) Under oxygen-rich conditions, however, is more difficult. A three-way catalyst, as used, for example, in gasoline engines, does not bring the desired effects only for diesel engines. developed: For this reason, for example, the method of selective catalytic reduction was ( "selective catalytic reduction" SCR).

p0004Furthermore, storage catalysts were tested on their use in view of the nitrogen oxide reduction. The coating of a storage catalyst contains, besides the usual noble metal components still barium carbonate or oxide. Thereby, it is possible that an excess of oxygen NO_x can be stored. In the noble metal components is nitric oxide (NO) from the exhaust gas to nitrogen dioxide (NO₂) Oxidized. This is then stored with the formation of barium on the catalyst. In this storage is formed on the barium-nitrate a grain layer, which slows the storage, because NO₂ must penetrate the continued storage through this layer. Since the storage capacity is therefore limited, the catalyst must be regenerated at regular intervals. This happens for example by briefly enriching the exhaust gas, that is, by a brief period with stoichiometric conditions. In reduced atmosphere, the nitrate converts back to (z. B.) Carbonate and nitric oxide to be released. This is immediately reduced to nitrogen. Since the regeneration is faster than the storage, the regeneration period can be much shorter than the storage periods.

p0005For the reduction of particulate emissions, particulate traps are known, which are constructed from a ceramic substrate. These have channels so that the exhaust gas to be purified can flow into the particulate trap. Adjacent channels are alternately closed, so that the exhaust gas on the inlet side enters the channel, passes through a ceramic wall and escapes through an adjacent channel on the exit side. Such filters achieve an efficiency of approximately 95% over the entire width of the particle sizes which occur.

p0006In addition to chemical interactions with additives and special coatings, the secure regeneration of the filter in the exhaust system of an automobile, still a problem. The regeneration of the particulate trap is required since the increasing accumulation of particulate matter in the flow to pass through channel walls has a constantly increasing pressure loss has the negative impact on engine performance. The regeneration comprises mainly the brief heating of the particulate trap or the accumulated therein particles so that the soot particles are converted to gaseous constituents. This can for example also be achieved that with the help of an upstream exothermic reaction (for example, oxidation of additionally injected into the Angasleitung fuel into an oxidation catalyst ( "post-combustion")), the exhaust gas for a short time reach the temperatures sufficient, the adhesive in the particulate trap particles convert. This high thermal loading of the particulate trap, however, has a negative impact on the service life.

p0007To avoid these discontinuous and thermally highly wear-promoting regeneration a system for continuously been Regeneration of filters developed (CRT: "continuous regeneration trap"). In such a system the particles at temperatures are already above 200 ° C by means of oxidation with NO₂ burned. The NO required for this purpose₂ is often generated by an oxidation catalyst which is arranged upstream of the particulate trap. Here, however, arises precisely with regard to the use in motor vehicles with diesel fuel is a problem that only an insufficient proportion of nitric oxide (NO) in the exhaust gas exists that the desired nitrogen dioxide (NO₂) Can be converted. As a result, can not be ensured so far that continuous regeneration of the particulate trap in the exhaust system takes place.

p0008It should be further borne in mind that in addition nichtumwandelbaren particles also oil or additional residues of additives are deposited in a particulate trap, which can not be regenerated readily. For this reason, known filters must be replaced at regular intervals and / or washed.

p0009In addition to a minimum reaction temperature and a specific residence must for the continuous regeneration of particles with NO₂ sufficient nitrogen oxide are provided. Tests concerning the dynamic emission of nitric oxide (NO) and particulate matter have clearly brought forth that the particles are then emitted just when no or very little nitrogen monoxide in the exhaust gas is present, and vice versa. It follows that a filter with real continuous regeneration substantially. is must act as a compensator or storage, thereby ensuring that the two reactants are simultaneously at a given moment in the required quantities in the filter yet. Further, the filter is to be arranged as close as possible to the internal combustion engine to already be able to accept very high temperatures immediately after the cold start. To provide the required nitrogen dioxide is upstream of the filter, an oxidation catalyst, wherein carbon monoxide (CO) and Reacting hydrocarbons (HC) and in particular nitric oxide (NO) into nitrogen dioxide (NO₂) Converted. In a close-coupled arrangement of this system of oxidation catalyst and filter in particular the position in front of a turbocharger is suitable, which is often used in diesel motor vehicles for increasing the boost pressure in the combustion chamber.

p0010Considering these fundamental considerations, so arises for actual use in the automotive industry, the question of how such a filter is constructed having a satisfactory filtration efficiency in such a position and in the presence of extremely high thermal and dynamic loads. The spatial conditions are particularly considered, which require a new approach to filter. While in the classical filters, which were arranged in the underbody of a motor vehicle, the largest possible volume in the foreground stood, a long residence time of the unreacted particles in the filter, thus ensuring a high efficiency, there is not enough space in a close-coupled arrangement or . room.

p0011To this end, a new concept has been developed which is known generally by the term "open filter system". This open filter systems are distinguished by the fact that in a constructive, mutual

p0012Closing the filter channels can be dispensed with. In this case, it is provided that the channel walls at least partially from porous or highly porous

p0013Material are structured and that the flow passages of the open filter deflecting or guide structures having. The effect of these fixtures that

p0014Flow or the particles contained therein are directed towards the areas of porous or hochporöserem material. It has surprisingly been found that the particles adhere through interception and / or impaction and / or in the porous channel wall. the Druclcunterschiede are in the flow profile of the flowing for the coming together of these Wirlcung

p0015Exhaust of importance. The deflection can also local Vacuum or pressure conditions arise which lead to a filtration effect through the porous wall, since the above-mentioned pressure differences have to be compensated.

p0016The particle trap is open, unlike the known closed Sieboder filter systems, because no flow dead ends are provided. This property can thus also serve to characterize such particulate filter, so that for example the parameter "freedom of flow" is suitable for the description. So is a "freedom of flow" of 20%, that 20% of the area are clearly represented in a cross-sectional analysis. In a particulate filter having a channel density of approximately 600 cpsi ( "cells per square inch ') with a hydraulic diameter of 0.8 mm, this freedom of flow would correspond to a surface area of ​​about 0.1 mm. In other words, this means that a particle trap then can be described as open, if he can basically run through completely by particles, even particles that are significantly larger than the actually filtered out particles (in particular the characteristic of the diesel and / or gasoline fuel particle size range). as a result, such a filters do not clog even with an agglomeration of particles during operation. a suitable method for measuring the openness of particle traps, for example, the examination to which diameter spherical particles can still trickle through a filter. in the present applications, a particle trap is particularly " open "if balls of greater than or equal to 0.1 mm can still trickle through, preferably spheres with a diameter above 0.2 mm. Such "open" filter elements are apparent for example from the documents DE 201 17 873 UI, DE 201 17 659 UI, WO 02/00326, WO 01/92692, WO 01/80978, whose disclosure content is hereby made completely into the present description. In view of the general configuration of honeycomb bodies with internal flow control surfaces are, for example, the German utility model DE 89 08 738 UI hints. This document describe honeycomb body, in particular a catalyst carrier body for motor vehicles, disposed of in layers, at least in partial areas strulcturierten sheets, which form the walls of a plurality of channels through which a fluid. It describes that in most applications, and in the usual dimensions of such Wabenlcörper the flow is laminar in the channels substantially, ie very small channel cross sections are used. Under these conditions, build on the channel walls relatively thick boundary layers, which reduce contact of the core flow in the channels with the walls. To effect turbulence in the exhaust gas flow within the channels and thus to ensure a close contact of the entire exhaust stream with a catalytically active surface of the channels, here the inverted sections are proposed, which form leading faces in the interior of the channel so that the exhaust gas is deflected transversely to the main flow direction becomes.

p0017Particularly with regard to the implementation of such an open particle trap, it is now an object of the present invention to improve the effectiveness in terms of implementation contained in the exhaust pollutants.

p0018In particular, the possibility should be opened to provide exhaust systems especially for automobiles with diesel engine of particularly small design.

p0019In addition, production, installation and maintenance of such exhaust systems should be significantly simplified and thus more cost-effective.

p0020These objects are achieved by a high-temperature resistant fiber sheet for a particulate trap for purifying exhaust gases of an internal combustion engine having the features of claim 1 and a corresponding particle trap having the features of claim 8. Further advantageous embodiments are described in the dependent claims, the outlined there individually characteristics or may occur in any, meaningful combination.

p0021The inventive high-temperature-resistant fiber layer of metal for a particulate trap for cleaning exhaust gases from mobile Verbrermungskraftmaschinen is characterized in that at least in a portion of a coating is provided which at least partially of an oxidation catalyst and / or a 3 -way catalyst and / or an SCR catalyst equivalent.

p0022The provision of such catalytically active coating has a number of advantages, which are subsequently briefly outlined. For example, to ensure that the original in the exhaust system components provided for oxidation or reduction and / or storage can be executed contained in the exhaust pollutants of low-volume or even can be entirely dispensed with. This has the consequence that the exhaust system can be run as such, significantly slimmer and smaller, thus, a simple structure, a simple maintenance and a low cost manufacturing of the exhaust system is made possible. Moreover, surprisingly, synergistic effects result. So a body having a fiber layer such particulate trap exhaust gas constituents are, for example, generated directly inside, to assist in the implementation or elimination of accumulated particles. These gas components are thus, directly produced and provided near the surface of the fiber layer, on the stick the particles. Thus, for example, the regeneration temperature of the particulate trap are also significantly reduced, for example from about 900 ° C to temperatures below 600 ° C.

p0023With regard to the arrangement of the at least one portion of the fiber layer is to be noted that this section can also extend over the entire surface of the fiber layer. However, it is also possible to provide a plurality of sections, which are coated and / or partially be uncoated may, where necessary, also different coating types, distinct section shapes or section surface areas can be selected. It is also possible that the at least one portion is located only on an outer surface or side of the high temperature-resistant fiber layer.

p0024With regard to the properties of the coating of an oxidation catalyst is to be noted that such catalysts are used to increase the speed of certain reaction without being consumed. By suitable catalyst substances can be achieved that the oxidation processes for CO (carbon monoxide) and HC (hydrocarbons) in the exhaust gas run at lower temperatures. By means of such coatings usually contain substances catalyst of the platinum group, gaseous hydrocarbons and carbon monoxide can be oxidized at exhaust temperatures already above 250 ° C in diesel engine exhaust. A special feature of such oxidation coatings can be seen in the fact that under certain circumstances an afterburning of anlagernden yet to soot hydrocarbons takes place, whereby the particulate emissions can be further reduced. So far they had been spared to provide for such a combination of oxidation-promoting coatings and filter elements in a unit, as it was feared that the catalytically active substances would be affected due to increasing coverage with particles. From this prejudice in the art has departed in the invention and developed a high-temperature resistant fiber layer, which enables the production of particularly effective particulate traps.

p0025If the three Schadstofrkomponenten CO, HC and NO_x (Nitrogen oxides) can be reduced by post-reaction, this can be achieved by coating the fiber sheet with such of the three -way catalyst. The effective catalyst substance in this case comprises platinum (Pt), palladium (Pd) or rhodium (Rh) in finely dispersed on a large surface. At a lambda value of 1 is CO to carbon dioxide (CO₂), CH to CO₂ and water (H₂O) is oxidized and NO_x to nitrogen (N₂) Reduced. This gave the following coating offers in terms of the oxidation catalyst:

p0026Pt / Pd = 2/1

p00270.93 to 1.2 grams of Pt / liter_katalysatorträgervolumen 0.46 to 0.6 grams of Pt / liter of catalyst support volume

p0028Regarding the multifunctional catalyst (reduction) it is proposed that the following relationships apply: Pt / Rh = 5/1

p00291.16 to 1.5 grams of Pt / Literκatalysatorträgervolumen 1.23 to 0.3 gram Rh / Literκatalysatorträgeι-volume

p0030Under catalyst carrier body volume the volume is understood which comprises the material of the carrier (honeycomb structure, etc), and the cavities formed by the carriers, channels and so on.

p0031The coating of a SCR catalyst can optionally also be formed multi-layered or multi-level. A possible urea-SCR catalyst system consists of several successively arranged partial areas of the coating that is applied to the fiber layer. The sub-regions can be arranged in the flow direction of the exhaust gas as follows: a coating of an oxidation catalyst (optional), the coating of a hydrolysis catalyst, the coating of an SCR catalyst and, if appropriate, a downstream oxidation catalyst. The optional upstream oxidation catalyst serves to increase the SCR activity at low exhaust gas temperatures (especially when diesel cars). An increase of NO₂Stake (optimum: 50 vol .-%) in the exhaust gas by means of partial oxidation of NO, the reaction rate of the SCR reaction in a temperature range below about 573 K can be increased significantly. In addition, at the catalyst surface, the oxidation of carbon monoxide to carbon dioxide and the reaction of incompletely unburned hydrocarbons to carbon dioxide and water. Without the use of such an upstream portion having an oxidation coating the oxidation of hydrocarbons would be made partly on the SCR catalyst, thus causing a reduction of nitrogen oxide conversion.

p0032Using the coating of a hydrolysis catalyst, the complete decomposition of an aqueous urea solution takes place even at low temperatures, eg. As 470 K. Below 470 K, the decomposition of the urea is problematic, since due to incomplete decomposition, undesirable byproducts , The coating of the SCR catalyst is used for the selective reduction of nitrogen oxides NO_x with ammonia to the unproblematic products nitrogen and water.

p0033According to another embodiment of the high temperature-resistant fiber layer comprises the coating washcoat. The coating of the relatively smooth surfaces of the fibers with washcoat has a magnification of the catalytically active surface result. These fissured surface firstly ensures a sufficiently large space for the fixing of a catalyst (eg, platinum, rhodium, etc.) and used the other hand to the turbulence of the exhaust gas flowing through, with a particularly intensive contact with the catalyst is effected.

p0034The application of catalysis demanding high surface area washcoat layer is known in such a way that the fiber layer (or later the entire particulate trap fiber layers and metal foils) is immersed in a liquid washcoat dispersion or sprayed with this. The excess washcoat dispersion is removed, dried in the wash coat of the fiber layer and finally calcined at temperatures usually above 450 ° C. During calcination, the volatile components of the washcoat dispersion are expelled, so that a temperature resistant and catalysis-promoting layer having a high specific surface area is generated. If necessary, this procedure was repeated several times to a desired layer thickness to to accomplish. The average coating thickness is preferably in a range of 0.001 to 0.02 mm, in particular from 0.005 to 0.012 mm.

p0035The washcoat usually consists of a mixture of an alumina and at least one Promoteroxid such as rare earth oxides, zirconium oxide, nickel oxide, iron oxide, germanium oxide and barium oxide. The washcoat dispersion must thereby during application to the honeycomb body having a good flow property as possible in order to achieve a desired, uniform layer thickness over the entire channel length.

p0036To achieve such a flow characteristic, known washcoat dispersions a particular pH, whereby only a limited solids content is allowed. However, tests have shown that such a washcoat dispersion has a time-dependent viscosity. This has the consequence that the washcoat dispersion gelled very rapidly and prevents the generation of a uniform layer thickness. This gelation can be delayed so that the washcoat dispersion is maintained in motion, that is either moved so that the dispersion or the wetted filter layer, in particular excited to vibrate.

p0037According to yet another embodiment of the fiber layer, this consists of a porous sinter and / or fibrous material (such as steel). Here, particular offer high temperature resistant and corrosion resistant steels with relatively high levels of chromium, nickel, aluminum and / or molybdenum. It is particularly advantageous that the fiber layer comprises fibers having an average diameter that is smaller than 0.082 mm, in particular lies in a range of 0.01 to 0.05 mm. To avoid that such a filter layer produces a high back pressure in the exhaust stream, it is suggested that the fiber layer has a porosity which is at least 50%, especially at least 75%, preferably at least 85%, and preferably even at least 95%. In this context it should be noted that such fiber layers relatively well with fibers an average length of 0.4 mm to 0.05 mm were prepared in which case preferably smaller fiber lengths must be selected with thicker fibers.

p0038It is further proposed that the fiber layer in a longitudinal section, substantially parallel to the largest outer surface has openings which have an extent of 0.01 mm to 0.5 mm in the center, in particular from 0.05 mm to 0.25 mm. Basically, it should be noted at this point that the fiber layer may comprise fibers in virtually any configuration, in particular, this is also random layers, tissue or similar structures are to be understood. It can also be regular structures only regionally, while in the other areas there is a rather chaotic arrangement of fibers.

p0039To ensure that sufficiently large cavities for particles or agglomerates thereof are provided, it is suggested here just for use in exhaust systems of diesel engines that a certain pore size is provided. To determine the pore size, a longitudinal section is used here by the material, the small cross sections of the pores or cavities shows that are mentioned here openings. All these openings have an extension in the above range in the middle. It is meant here an average of all maximum extensions of recognizable longitudinal section openings. As applies to the dimension of the opening on the already coated fiber layer, also a corresponding average fiber distance can be used, which is to be selected preferably less than 0.6 mm, in particular between 0.05 mm and 0.35 mm.

p0040It is further proposed that the fiber layer has a thickness which is less than 3 mm, in particular less than 1.5 mm, preferably less than 0.5 mm and preferably less than 0.1 mm. The thicknesses mentioned herein are chosen precisely with regard to the use of the fiber layer of particulate traps for purifying exhaust gases from mobile Verbrennungslcraftmaschinen. According to another aspect of the invention, a particulate trap is proposed for purifying exhaust gases from mobile internal combustion engines, which has at least one, partially structured metal foil and at least one high temperature-resistant fiber layer according to the type described above, wherein preferably more patterned metal foils and several fiber layers alternately with each other and in particular wound together are arranged in a housing. Here an "open" particle trap is formed in particular as it was described at the beginning. Thus, it is particularly advantageous to form an "open" filter element, as in the documents DE 201 17 873 UI, DE 201 17 659 UI, WO 02 / 00326, WO 01/92692, WO 01/80978 is described.

p0041It is further proposed that the particle trap is formed extending to the axis channels substantially parallel with baffles, preferably baffles the metal foil, extending into at least part of the channels and a diversion of air flowing through the ducts gases toward the fiber layer effect. Such fins may be formed by projections, knobs, Milcrowellungen, blades or similar structures. It is also possible that these guide surfaces are formed by edges of holes in such metal foils. The fins themselves can also have holes.

p0042According to a further embodiment of the particle trap has a volume, and the coating amount of the particle trap in relation to said volume is in the range of 20 to 300 g / 1 (grams per liter), preferably even between 50 and 120 g / 1st Sub-volume is meant in this context the volume, which is composed of the metal foils, the fiber layers as well as the channels formed. Typically, such a volume in the range of 0.01 1 to 1.5 1, preferably between 0.3 1 and 0.8 1st

p0043Furthermore, it is proposed that the at least one at least partially structured metal foil having openings, which extend over at least a Forest-wide extend, preferably even more than 2, in particular 3 feature sizes. This means that, for example, such a breakthrough combines several formed by the structure, adjacent channels together. In this way, a particularly effective mixing of the partial exhaust-gas streams is ensured, without the particulate trap before an undesirably high dynamic pressure is generated. It should also be noted that the openings extend in the plane of the metal sheet substantially.

p0044The invention will now be explained in more detail with reference to FIGS. It should be noted that the figures particularly preferred embodiments of the invention show, the invention is not limited thereto. Show it:

p0045Fig. 1 shows schematically and in an exploded view a detail of a

p0046Particulate trap according to the invention,

p0047FIG. 2 shows a further detail an embodiment of the present invention

p0048Particulate trap,

p0049Fig. Figure 3 shows schematically an embodiment of an exhaust system of a mobile Verbreimungsl aftmaschine,

p0050Fig. 4 schematically and in perspective a further embodiment of the particulate trap according to the invention,

p0051Fig. 5 shows diagrammatically a longitudinal section through an inventive embodiment of the fiber layer, and

p0052Fig. 6 is a further longitudinal section of a fiber layer in the coated state.

p0053Fig. 1 shows schematically and in an exploded view a detail of a particulate trap, such as, for example, to the exhaust gas treatment of mobile Internal combustion engines is used. Shown are two erfmdungs ​​according fiber layers 1, between which a metal foil 14 is disposed. The fiber layers 1 each have a section 3 in which a coating 4 is disposed. This coating 4 can be the one oxidation catalyst, a three-way catalyst and / or an SCR catalyst. Preferably, the metal films 14 (at least in some areas) a catalytically active and / or latching coating. Usually, the adjacent layers abut each other and are preferably connected to one another by joining techniques, in particular soldered together. For this it is necessary, for example, not to coat a portion, in particular the edge of the fibrous sheet 1, to ensure the possibility for forming connections by technical joining here.

p0054The structuring of the metal foil 14 has the result that this "sandwich" of smooth layers (fiber layer 1) and corrugated layer (metal foil 14) can be flowed through an exhaust gas in a flow direction 21st case baffles 18 are mounted in the channels 17, a have turbulence of the partial gas streams result, so that these are in particular directed against the coated fiber layer first the structure of metal foil 14 is here a corrugated structure with a predetermined Strulcturweite 36. Preferably, the guide surfaces 18 and below the apertures 19 are made larger than the structural width 36, so that a plurality of adjacent channels 17 can be connected to each other through the openings 19th

p0055Fig. 2 shows an arrangement of metal foils 14 and a fiber layer 1 in detail. Again, the metal foils 14 and the fiber layer 1 are alternately arranged, wherein the structure of the metal foils 14 in conjunction with the fiber layer 1 forms passages 17 which can flow for the exhaust gas in a flow direction 21st In the channels 17 protrude vanes 18 which have been prepared by punching, pressing or in some other way from the metal film 14 itself. This breakthroughs 19 are created simultaneously, so that by the by the a Channel 17 flowing gas a partial edge flow "peeled" and can be executed passes to the fiber layer. 1 In this way, the particles 22 are entrained, and led to the fiber layer. 1 They remain on the outer surface 9 stick for example, or are deposited in cavities, pores or similar openings of the fiber layer on the first fibrous layer 12 shown here has a plurality of chaotically arranged fibers 6, which are provided with a coating 4. Overall, the fiber layer 1 has a thickness 12 which is less than 3 mm.

p0056Fig. Figure 3 shows schematically the structure of an exhaust system of an automotive internal combustion engine 13. The in Verbrennungsl aftmaschine 13 generated exhaust gas is fed via an exhaust line 23 wide variety of components for waste gas treatment before it is ultimately emitted to the environment. . The exhaust system is shown in Figure 3, comprises in flow 21 after the other following components: a starter catalyst 24, a turbocharger 25, an oxidation catalyst 26, a reducing agent supply 27, a mixer 28, a particulate trap 2 of the invention and a main catalytic converter 29.

p0057The start catalyst 24 is characterized by its particularly small volume (for example, less than 0.1 liters) and is applicable heated due to its low heat capacity and its proximity to the engine is already very short time after engine start, that a catalytic reaction contained in the exhaust pollutants is possible (for example, temperatures above 230 ° C after a few seconds). The function of the oxidation catalyst 26 before a particulate trap 2 for regeneration has been described in detail above. The reducing agent supply 27 and the mixer 28 is used, for example, the supply of solid or liquid urea, so that a conversion of pollutants to the SCR process is possible. The mixer 28 may be designed as a guide surface, grid, honeycomb or similarly. However, it is also possible to omit the mixer 28 prior to the particulate trap 2, since the Filter 2 itself also causes turbulence of the exhaust gas streams or a fine distribution of the injected reducing agent. The downstream main catalyst 29 typically has a relatively large volume, in particular greater than 1.5 liters.

p0058Fig. 4 shows in perspective and schematically the structure of a particle trap 2. The particle trap 2 for cleaning exhaust gases from mobile internal combustion engines comprises a patterned metal foil 14, and a high temperature-resistant Faseriage l, arranged spirally about an axis 16 of the particulate trap 2 (alternatively, are also easy stacking arrangements , S-shaped or other Schlingungen turns of metal foils and / or fiber layers possible). The metal foil 14 and the fiber layer 1 form channels 17, which extend substantially parallel to the axis 16 through the particle trap 2 pass. The composite of metal film 14 and fibrous layer 1 is housed in a casing 15 and advantageously also connected fastening techniques. In the illustrated embodiment of the particle trap 2, the housing 15 protrudes beyond the end faces 34 of the particulate trap 2 and the metal foil 14 and the fiber layer first The material thickness 30 of the corrugated metal sheet 14 is preferably in a range below 0.05 mm, preferably even below 0.02 mm. This provides particularly that the material thickness 30 or the coating 4 (not shown), or other parameters of the particulate trap 2 over the entire length 31 of the particulate trap 2 are not constant. Ie., For example, that the particulate trap 2 in a first longitudinal section 32 has a lower heat capacity, a higher porosity, a greater load in terms of catalytic alctiven coating, an increased number / size of apertures 19, vanes 18 or fibers has, as in a second Längenäbschnitt 33. in principle, the division of the particulate trap 2 in more than two longitudinal portions is also possible.

p0059The particulate trap 2 shown has a volume 20, which in the filled by the fiber layer 1 and the metal foil 14 volume inside the

p0060Housing 20 is characterized, wherein the volume of the channels 17 also is included. With regard to the coating 4, the particulate trap according to the invention is provided with such an amount which is in the range of 20 to 300 g / 1st It is possible that this amount is disposed over the total length 31 uniformly to the outer surfaces 9 of the fiber layer 1 and / or the casing films 14, but is also possible that only the fiber layer 1, or only partial areas of the metal foil 14 with a catalytically active coating, 4 are provided. It is also possible that different types or amounts of the coating are provided in four different lengths.

p0061Fig. 5 shows schematically a longitudinal section 8 through the fiber layer 1. It can be seen that the fiber layer 1 is formed by a plurality of fibers 6, which are partially listed here, are partly connected to each other messy. The fibers 6 preferably have a diameter in the range of 7 0.012 and 0.035 mm. The arrangement of the fibers 6 in the longitudinal section 8 holes 10 are formed. These represent practically represents a cross section of the cavities formed in the interior of the fiber layer. 1

p0062Fig. Figure 6 schematically shows likewise a longitudinal section 8 of the fiber layer 1, whereby now the fibers 6 are carried out with a coating 4. The coating 4 comprises washcoat 5 which forms sufficient opportunity for the addition of catalytically active substances 35, due to its rugged surface. Despite the coating 4 8, the longitudinal section still openings 10 with an extension 11th This extension 11 all openings 10 is on average from 0.05 to 0.4 mm. It is preferred simultaneously having a porosity of approximately 87% observed.

p0063The present invention is the result of a variety of sophisticated technical attempts to improve the effectiveness of particle traps in the exhaust systems of automotive internal combustion engines. LIST OF REFERENCE NUMBERS

p0064fiber layer

p0065particulate trap

p0066section

p0067coating

p0068washcoat

p0069fiber

p0070diameter

p0071longitudinal section

p0072outer surface

p0073opening

p0074expansion

p0075thickness

p0076Internal combustion engine

p0077metal foil

p0078housing

p0079axis

p0080channel

p0081baffle

p0082breakthrough

p0083volume

p0084flow direction

p0085particle

p0086exhaust pipe

p0087Start catalyst

p0088turbocharger

p0089oxidation catalyst

p0090Reducing agent supply

p0091mixer main catalyst

p0092material thickness

p0093total length

p0094First section length

p0095Second longitudinal portion

p0096face

p0097substance

p0098Forest-wide