Title of Invention

EXHAUST GAS FILTER AND METHOD FOR CLEANING AN EXHAUST GAS.

Abstract

This invention relates to an exhaust gas filter (11) for cleaning an exhaust gas of an internal combustion engine, formed by at least one strip-shaped filter layer (1) with at least one filter region (2) made of material through which a fluid can at least partly flow and, for example, a metal foil (4). The filter layer (1) has at (east one contact region (3) with a catalytIcally active coating for the conversion of gaseous components of the exhaust gas and a filter region (2) for filtering out particulates from the exhaust gas.

Full Text

The invention relates to an exhaust gas filter for cleaning an exhaust gas of an internal combustion engine comprising at least one strig-shajped filter layer, and also a method for cleaning an exhaust gas of an internal combustion engine. Partly because of the relatively low fuel consumption, motor vehicles with diesel engines are being sold in increasing numbers in many countries. In comparison with gasoline-powered motor vehicles, diesel vehicles have a significantly reduced carbon dioxide emission, but the proportion of particulates produced during combustion in a diesel engine is much greater than that of a gasoline engine. In many countries motor vehicles have to comply with emission standards setting maximum limits for the concentration of individual components in the exhaust gas of the motor vehicle that is emitted into the environment. If the cleaning of exhaust gases, in particular of diesel engines, is now considered, hydrocarbons (HC) and carbon monoxide (CO) in the exhaust gas can be oxidized in a known way, in that they are brought into contact for example with a catalytically active surface. The reduction of nitrogen oxides (N0x) under oxygen-rich conditions is more difficult however. A three-way catalytic converter, as used for example in the case of spark-ignition engines, does not provide the desired effectiveness. For this reason, the method of selective catalytic reduction (SCR) has been developed. Furthermore, N0x adsorbers have been used on a trial basis for reducing the nitrogen oxides in exhaust gas. - 2 - Particulate traps which are constructed from a ceramic substrate are also known for the reduction of particulate emissions in the exhaust gas of diesel engines in particular. These traps have passages, so that the exhaust gas which is to be cleaned can flow into the particulate trap. The adjacent passages are alternately closed off,, so that the exhaust gas enters the passage on the inlet side, passes through the ceramic wall and escapes again through the adjacent passage on the outlet side. Particulate traps of this type are known as closed particulate filters. They achieve an effectiveness of about 95% across the entire range of the particulate sizes occurring. The reliable regeneration of the filter in the exhaust system of an automobile causes problems. It is necessary to regenerate the particulate trap since the increasing accumulation of particulates in the passage wall through which the exhaust gas is to flow causes a steadily increasing loss of pressure, which has adverse effects on the power of the engine. The regeneration substantially comprises brief heating of the particulate trap, or of the particulates which have collected therein, so that the particulates are converted into gaseous constituents. However, this high thermal loading of the particulate trap has adverse effects on its service life. To avoid this discontinuous regeneration, which in thermal terms leads to a high likelihood of wear, a system for the continuous regeneration of filters has been developed (Continuous Regeneration Trap, CRT) . In such a system, the particulates are converted by means of oxidation with NO2 at temperatures just above 2 00°C. This temperature limit is much lower than in the case of classical particulate traps. The NO2 required for this purpose is often generated by an oxidation catalyst which is arranged upstream of the particulate - 3 - trap. However, specifically with a view to use in motor vehicles which use diesel fuel, there is the problem here that the exhaust gas only contains an insufficient level of nitrogen monoxide (NO) which can be converted into the desired nitrogen dioxide (N02) . Consequently, it has not been possible so far to ensure that the particulate trap is continuously regenerated in the exhaust system. In addition to a minimum reaction temperature and a specific residence time, it is also necessary for sufficient nitrogen oxide to be provided for the continuous regeneration of particulates with NO2 . Tests relating to the dynamic emission of NO and particulates have clearly demonstrated that the particulates are emitted specifically when there is no NO or only a very small amount of NO in the exhaust gas, and vice versa. This means that a filter with real continuous regeneration must essentially act as a compensator or store, to ensure that the two reaction partners are simultaneously present in the required quantities in the filter at a given time, at which one of the conditions that are satisfied is the minimum reaction temperature. Furthermore, the filter is to be arranged as close as possible to the internal combustion engine, in order to allow it to reach temperatures which are as high as possible immediately after a cold start. To provide the required NO, an oxidation catalyst, which converts carbon monoxide and hydrocarbons and in particular also nitrogen monoxide into nitrogen monoxide, is to be connected upstream of the filter. The filter material required for this, which is capable of withstanding high thermal loading, is known from German Patent Application DE 101 53 283, which is not a prior publication. This document describes a filter system which can essentially be referred to as an "open _ 4 - filter system" . An open system of this type dispenses with an inbuilt alternating closure of the filter passages. The passage walls consist at least partly of porous or highly porous material; the flow passages of the open filter have diverting or guiding structures, which direct the exhaust gas with the particulates contained in it toward the regions made of porous or highly porous material. A particulate filter is referred to as open whenever it can in principle be passed through completely by particles, to be precise even by particles which are considerably larger than the particulates that are actually to be filtered out. As a result, such a filter cannot become clogged during operation, even if there is an agglomeration of particulates. A suitable method for measuring the openness of a particulate filter is for example that of testing up to which diameter spherical particles can still trickle through such a filter. In the case of the present applications, a filter is open in particular when spheres of a diameter greater than or equal to 0.1 mm can still trickle through, preferably spheres with a diameter above 0.2 mm. However, the open particulate filter described in this document has the problem that, owing to the absolutely necessary oxidation catalyst which has to be arranged upstream of the particulate trap in the direction of flow, the cold-starting behavior of the particulate trap is relatively sluggish, i.e. the particulate trap is only heated up relatively slowly by the oxidation catalyst, which has to be heated up first. On this basis, the object of the invention is to provide an exhaust gas filter for cleaning an exhaust gas of an internal combustion engine, and also to provide a method for cleaning an exhaust gas of an internal combustion engine, which filter and which - 5 - method have a rapid cold-starting behavior and satisfy the condition of continuous regeneration. This object is achieved by an exhaust gas filter as claimed in claim l.and a method for cleaning an exhaust gas as claimed in claim 13. Advantageous developments and refinements are the subject of the independent claims. An exhaust gas filter according to the invention for cleaning an exhaust gas of an internal combustion engine is formed by at least one strip-shaped filter layer with at least one filter region made of material through which a fluid can at least partly flow and, if appropriate, a metal foil. The filter layer has at least one contact region with a catalytically active coating for the conversion of gaseous components of the exhaust gas and a filter region for filtering out particulates from the exhaust gas. In other words, the contact region of the filter layer allows an oxidative conversion of the gaseous constituents of the exhaust gas, with especially carbon monoxide and hydrocarbons, and in particular also nitrogen monoxide, being converted into nitrogen dioxide. Consequently, the contact region ensures that, once the operating temperature has been reached, there is sufficient NO2 in the exhaust gas flowing through the filter region that the exhaust gas filter can be operated in a continuous regeneration mode with respect to the particulates filtered out, so that it is possible to dispense with the formation of an upstream oxidation catalyst to provide the necessary NO2. Consequently, installation of the exhaust gas filter close to the engine is possible. This brings about more rapid heating-up of the actual exhaust gas filter, and consequently much improved cold-starting behavior, - 6 - in comparison with the open filter system, known from the prior art with an upstream oxidation catalyst. It is particularly advantageous in this connection that the contact region can be formed in regions in which the filter layer is connected to possibly adjacent sheet-metal layers or else to a cladding tube enclosing the exhaust gas filter. The formation of such a connection by means of a joining technique often takes place by brazing, but welding or other joining methods are also possible. If the filter layer is made of a material through which a fluid can at least partly flow, the formation of this connection to other sheet-metal layers and/or the cladding tube generally has the effect that in this region the filter layer can no longer be flowed through by a fluid, or only to a very small extent, since, for example in the case of brazing, the material is saturated with brazing material, so that absorption of particulates is no longer possible here. Consequently, these regions contribute to the effectiveness of the exhaust gas filter only to a reduced extent. For this reason it is advantageous to form the contact regions in these regions, since as a result, with the same construction, the filtering effectiveness of the filtration of particulates from the exhaust gas is not significantly reduced, but the installation of a separate oxidation catalyst can be avoided. According to an advantageous refinement of the exhaust gas filter, the contact region at least partly comprises a metal foil. The formation of the contact region at least partly from a metal foil allows simple coating of the contact region in an advantageous way, since a metal foil can be coated with catalytically active material in a known way, for example in the form of a so-called washcoat into which the catalytically active substances, for example noble metals such as - 7 - platinum or rhodium, can be introduced. According to the invention, it is also possible to use already-coated films for the formation of the contact region. According to a further preferred refinement, the metal foil is microstructured. With appropriate configuration of the structures, a microstructured metal foil has the effect that the flow in the flow passage becomes more turbulent and no marginal layers of laminar flow form. This has the effect that a greater proportion of the gas stream is diverted in the direction of the material regions through which a fluid can at least partly flow. As a result, the effectiveness of the filter is improved overall in an advantageous way. Furthermore, depending on the ratio of the thickness of the metal foil to the thickness of the material through which a fluid can at least partly flow, a microstructuring of the metal foil can be used to even out the thicknesses between the contact region and the filter region. Moreover, the micro-undulation of the metal foil allows a significantly increased reaction area for the conversion of the at least one gaseous constituent of the exhaust gas. According to a still further advantageous refinement of the exhaust gas filter, the contact region consists at least partly of the material through which a fluid can flow. This advantageously allows the simple production of the exhaust gas filter, since for example the entire filter layer consists only of the material through which a fluid can flow and this is coated or impregnated with the catalytically active material only in the contact region. According to a further advantageous refinement of the exhaust gas filter, it has a main direction of flow in which it is flowed through by the exhaust gas. The contact region is formed upstream of the filter region - 8 - in the main direction of flow. This advantageously allows the contact region to be formed specifically also in the edge region on the gas inlet side, which is frequently used for forming a connection between the various filter layers and/or metal layers and/or to the cladding body. Consequently, there is in any case only a reduced filtering effectiveness in this region, since, depending on the type of joining connection that is formed, the material through which a fluid can flow is saturated with brazing material and/or welding additive for example, and/or a compression of this region occurs. Moreover, such a refinement of the exhaust gas filter according to the invention has the advantage that a sufficiently large amount of nitrogen dioxide is available very quickly for the region contributing to the effectiveness of the particulate filtering process, that is for the downstream filter region, so that the filter region can also be operated in a CRT mode very quickly even after a cold start. According to a further advantageous refinement of the exhaust gas filter, the contact region is formed in the end region on the gas inlet side of the exhaust gas filter, preferably in a linear region of less than 20% of the axial length of the exhaust gas filter, particularly preferably in a linear region of less than 10% of the axial length of the exhaust gas filter. This makes it possible in an advantageous way to provide a sufficiently large amount of nitrogen dioxide for the CRT operation of the filter region with only a small effect on the filtering effectiveness of the filter region. Moreovei:, the formation of the contact region on the gas inlet side leads to protection against blowing out, by which the edge regions of the filter and/or sheet-metal layers on the gas inlet side that are subjected to considerable loading from pulses of exhaust gas are protected against fraying, so that - 9 - the service life of the exhaust gas filter is increased. According to an advantageous refinement of the exhaust gas filter, the exhaust gas filter is formed by intertwined layers, which are at least partly filter layers. Other layers may for example be sheet-metal layers, which may be structured or of an essentially smooth configuration. It is particularly advantageous in this connection that the exhaust gas filter is formed by essentially smooth sheet-metal layers and structured filter layers or else by essentially smooth filter layers and structured sheet-metal layers. Such a construction allows the exhaust gas filter to be constructed for example as a honeycomb body from smooth and structured layers. The decision whether structured filter layers and smooth sheet-metal layers or structured sheet-metal layers and smooth filter layers are to be chosen is dependent on the requirements that the exhaust gas filter has to meet. According to a further advantageous refinement of the exhaust gas filter, the metal foil and the material through which a fluid can at least partly flow are connected to each other by a joining technique. It is particularly preferable in this connection that the metal foil and the material through which a fluid can at least partly flow are welded, brazed and/or riveted, preferably welded and/or brazed, particularly preferably brazed. This advantageously allows a stable connection between the metal foil and the material through which a fluid can at least partly flow, which has positive effects on the durability of the filter layer. It is particularly advantageous in this connection if the metal foil is formed as a contact region upstream of the filter region in the region of the exhaust gas filter on the gas inlet side. The metal foil then also serves at the same time as a - 10 - protection against blowing out in this partial region of the exhaust gas filter which is subjected to considerable loading from pulses of exhaust gas of the internal combustion engine and alternating thermal stresses. The effect of these pulses of exhaust gas is further intensified if it is installed particularly close to the engine. According to an advantageous refinement of the exhaust gas filter, the material through which a fluid can at least partly flow is made up of metal fibers. This is advantageous since such a material through which a fluid can flow is very resistant to heat and consequently can be exposed to the alternating thermal loads in the exhaust system of a motor vehicle over a relatively long service life. It is particularly advantageous if the material through which a fluid can flow is made up of metal fibers in a sintered form. According to a further aspect of the inventive idea, a method for cleaning an exhaust gas of an internal combustion engine is proposed, which method is carried out in particular in an exhaust gas filter according to the invention. According to the method according to the invention, both a conversion of ' the gaseous constituents of the exhaust gas and a filtering-out of particulates from the exhaust gas take place in a honeycomb body. According to an advantageous refinement of the method, the conversion of the gaseous constituents of the exhaust gas takes place upstream of the filtering-out of particulates with respect to a main direction of flow through the exhaust gas filter. This advantageously allows the provision of nitrogen dioxide, which is required for the CRT operation of the filter region of the exhaust gas filter. It is consequently possible in an advantageous way to - 11 - dispense with a separate oxidation catalyst upstream of the exhaust gas filter. This allows installation of the exhaust gas filter closer to the engine, providing it with improved cold-starting behavior in comparison with the open filter systems known from the prior art. According to an advantageous refinement of the method, the conversion of the gaseous particulates is catalyzed by at least one catalyst, preferably a noble metal catalyst. This advantageously allows the operating temperatures of the exhaust gas filter to be lowered. The invention is now explained in more detail on the basis of the figures, which show particularly advantageous and particularly preferred refinements of the exhaust gas filter according to the invention and of the method according to the invention. However, the invention is not restricted to the exemplary embodiments that are represented in the figures. Figure 1 shows a first exemplary embodiment of a filter layer of an exhaust gas filter according to the invention in longitudinal section; Figure 2 shows a second exemplary embodiment of a filter layer of an exhaust gas filter according to the invention in longitudinal section; Figure 3 shows an exemplary embodiment of a fi 1 ter layer of an exhaust gas filter according to the invention in a perspective representation; and Figure 4 shows an exhaust gas filter according to the invention. - 12 - Figure 1 shows a first exemplary embodiment of a filter layer 1, which serves for the construction of an exhaust gas filter according to the invention. The filter layer 1 has a filter region 2 and a contact region 3. The filter region 2 is formed from material through which a fluid can at least partly flow. The filter region 2 therefore consists of a porous or highly porous material. It is preferably formed from metal fibers, particularly preferably from sintered metal fibers. The filter region 2 has a high thermal stability. In this exemplary embodiment of a filter layer 1, the contact region 3 is formed as a metal foil 4. The contact region 3 is coated with a catalytically active material. It is particularly preferred here for the coating to be in the form of a washcoat into which noble metal catalysts are introduced. In the contact region 3, the at least partial conversion of at least one gaseous constituent of an exhaust gas which is to be cleaned in the exhaust gas filter occurs. The reactions of the gaseous constituent or constituents that are catalyzed by the catalytically active coating comprise in any event the conversion from NO to NO2, and it is furthermore possible according to the invention also to convert hydrocarbons that reach the exhaust gas filter unburned, as well as carbon monoxide. The filter region 2 can at least partly be flowed through by a fluid. In this filter region 2, the particulates contained in the exhaust gas are filtered out. They occur to an especially great extent in the exhaust gas of diesel engines. When an exhaust gas filter is made up at least partly by filter layers 1, interception and/or impaction of the particulates on and/or in the porous filter region' 2 causes adhesion of at least some of the particulates that are in the exhaust gas. For this effect to materialize, the pressure differences in the flow profile of the flowing - 13 - exhaust gas are of significance. This effect can be further enhanced by micro-structuring in the metal foil 4 and in the adjacent sheet-metal layers (not shown in Figure 1) , since local subatmospheric or superatmospheric pressure conditions additionally occur. These increase the filtration effect through the porous wall. The metal foil 4 and the filter region 2 overlap in a connecting region 5. In this region, a connection by a joining technique is provided between the metal foil 4, that is the contact region 3, and the filter region 2. This connecting region 5 may be produced for example by riveting, brazing or welding or by a combination of at least two of these methods. In the case of brazing, various brazing methods in which the brazing material is applied as powder or a brazing material foil are possible. Furthermore, it is possible according to the invention that the metal foil 4 has micros true tures, preferably micro-undulations. These may serve on the one hand for preventing laminar flows in the edge region; on the other hand, however, it is also possible by this means to compensate in an advantageous way for a difference in height between the filter region 2 and the contact region 3 and so simplify the construction of the exhaust gas filter. This region may consist of particularly thin foil, for example with a thickness of 15 to 30 m, and/or have holes, in order to keep the thermal capacity low, which improves the cold-starting behavior. It is also advantageously possible furthermore to compact the connecting region 5. This can take place by pressing, rolling or else as part of a welding method, such as for example the' roller seam welding method. - 14 - Figure 2 shows a further exemplary embodiment of a filter layer 1 for the construction of an exhaust gas filter according to the invention. This filter layer 1 also has a filter region 2 and a contact region 3. However, as a difference from the exemplary embodiment shown in Figure 1, the contact region 3 is also formed from porous material, which has been coated or impregnated with a catalytically active material. Particularly advantageous in this connection is the impregnation of the contact region 3 with a washcoat which contains the noble metal catalysts. It is advantageously possible to pre-treat the contact region 3, in order to reduce the amount of coating or washcoat required. Here it is advantageously possible to perform a pre-impregnation with brazing material, which is absorbed by the porous or highly porous material of the contact region 3. Furthermore, the contact region 2 may also be pre-treated by a compression, for example by pressing or rolling, in order to reduce the amount of the washcoat that is absorbed. The exemplary embodiments of a filter layer 1 shown in Figures 1 and 2 are represented in a smooth form by way of example. However, the filter layer 1 may also be structured, preferably undulated. It is possible according to the invention to combine smooth filter layers 1 with undulated layers (not represented here) to form an exhaust gas filter. This may take place for example by constructing a honeycomb body known per se for example in a spiral, S, SM or some other form. However, it is also possible for an' exhaust gas filter, for example in the form of a honeycomb body, to be constructed by combining a structured filter layer 1 with smooth further layers. Figure 3 shows an exemplary embodiment of a structured, that is undulated, filter layer 1. This filter layer 1 has a first contact region 6, a second contact region - 15 - 7, a first filter region 8 and a second filter region 9. In the two contact regions 6, 7, the conversion of at least some of the gaseous constituents of the exhaust gas takes place. The conversion of NO to N02 preferably takes place in these regions. With the N02 produced as a result, it is possible to operate the exhaust gas filter according to the invention in the CRT mode. The construction of a number of contact regions 6, 7 has the effect on average of a more even distribution of the N02 content in the axial direction 10, since not only an absolute maximum of the NO2 content occurs here at the end of the first contact region 6, but two local maxima respectively occur at the end of the first contact region 6 and at the end of the second contact region 7. The formation of further contact and filter regions is also possible according to the invention. Figure 4 shows an exhaust gas filter 11 according to the invention. This is flowed through by an exhaust gas stream 12 in the axial direction; the exhaust gas stream 12 flows into the exhaust gas filter 11 through the gas inlet side 13 and leaves it through the gas outlet side 14. The exhaust gas filter 11 is constructed as a honeycomb body. As shown in the small detailed region, the exhaust gas filter 11 is made up of smooth layers 15 and structured layers 16, which alternate with one another and are intertwined in an S-shaped manner. According to the invention it would be possible equally well for smooth layers 15 and structured layers 16 to be combined in some other way, for example to wind them in a spiral or SM form, or in any other forms. The smooth layers 15 and the structured layers 16 form passages 19 through which a fluid can flow, for example the exhaust gas stream 12. It is possible according to the invention to use filter layers 1 as smooth layers and sheet-metal layers as - 16 - structured layers 16, but it is also possible equally well to use filter layers 1 as structured layers 16 and sheet-metal layers as smooth layers 15. The at least partial use of filter layers 1 both as smooth layers 15 and as structured layers 16 is also possible according to the invention. On the gas inlet side 13, the exhaust gas filter 11 has a contact region 3, in which the conversion of at least part of at least one gaseous component of the exhaust gas stream 12 takes place. The conversion of nitrogen oxide into nitrogen dioxide, that is of NO to N02, preferably takes place in the contact region 3, so that the proportion of NO2 that is necessary for CRT operation is produced by the conversions in the contact region. The joining of the smooth layers 15 to the undulated layers 16 and/or to the cladding tube (not explicitly shown), which surrounds the honeycomb body, also preferably takes place at least in the contact region 3. The formation of the contact region in the form of metal foils which are connected to the filter region 2 also provides protection against blowing out on the gas inlet side 13, since, without protection against blowing out, the gas inlet side in particular is subjected to increased aging, because particularly great loading is exerted on the layers 15, 16 by the exhaust gases of the exhaust gas stream 12 impinging in the form of pulses. In comparison with the axial length 17 of the exhaust gas filter 11, the linear extent 18 of the contact region 3 is chosen to be much less. The linear extent 18 of the contact region 3 is preferably less than 20%, particularly preferably less than 10% of the axial length 17 of the exhaust gas filter 11. Consequently, it is possible in an advantageous way to provide sufficient NO2 for operation in the CRT mode by forming the contact region 3 in the region of the gas inlet - 17 - side 13 for the filter region 2. Consequently, without forming an additional oxidation catalyst upstream of the exhaust gas filter 11, it is possible to install the exhaust gas filter 11 close to the engine, which brings about very good cold-starting behavior of the exhaust gas filter 11. Furthermore, production costs can be saved in this way, since a separate oxidation catalyst does not have to be formed upstream of the exhaust gas filter 11. - 18 -List of designations 19 WE CLAIM 1. An exhaust gas filter (11) for cleaning an exhaust gas of an interna combustion engine, formed by at least one strip-shaped filter layer (1) with at least one filter region (2) made of material through which a fluid can at least partly flow and, for example, a metal foil (4), characterized ir that the filter layer (1) has at least one contact region (3) with a catalytically active coating for the conversion of gaseous components of the exhaust gas and a filter region (2) for filtering out parttculates from the exhaust gas. 2. The exhaust gas filter (11) as claimed in claim 1, wherein the contact region (3) at least partly comprises a metal foil (4). 3. The exhaust gas filter (11) as claimed in one of the preceding claims, wherein the metal foil (4) is microstructured. 4. The exhaust gas filter (11) as claimed in one of the preceding claim, wherein the contact region (3) consists at least partly of the material through which a fluid can flow. 5. The exhaust gas filter (11) as claimed in one of the preceding claims, wherein the exhaust gas filter (11) has a main direction of flow, in which it is flowed through by the exhaust gas, and in that the contrac region (3) is formed upstream of the filter region (2) in the main direction of flow. 20 6. The exhaust gas filter (11) as claimed in claim 5, wherein the contact region (3) is formed in the end region (14) on the gas inlet side of the exhaust gas filter (11), preferably in a linear region of less than 20% of the axial length (17) of the exhaust gas filter (11), particularly preferably in a linear region of less than 10% of the axial length (17) of the exhaust gas filter (11). 7. The exhaust gas filter (11) as claimed in one of the preceding claims, wherein the exhaust gas filter (11) is formed by intertwined layers (15,16), which are at least partly filter layers (1). 8. The exhaust gas filter (11) as claimed in claim 7, wherein the exhaust gas filter (11) is formed by essentially smooth sheet-metal layers (15) and structured filter layers (1). 9. The exhaust gas filter (11) as claimed in claim 7, wherein the exhaust gas filter (11) is formed by essentially smooth filter layers (1) and structured sheet-metal layers (16). 10. The exhaust gas filter (11) as claimed in one of the preceding! claims, wherein the metal foil (4) and the material through which a fluid can at least partly flow are connected to each other by a joining technique. 21 11. The exhaust gas filter (11) as claimed in claim 9, wherein the metal foil (4) and the material through which a fluid can at least partly flow, are welded, brazed and/or riveted, preferably welded and/or brazed, particularly preferably brazed. 12. The exhaust gas filter (11) as claimed in one of the preceding claims, wherein the material through which a fluid can at least partly flow is made up of metal fibers. 13. The method for cleaning an exhaust gas of an internal combustion engine, in particular in an exhaust gas filter (11) as claimed in one of the claims 1 to 12, wherein both a conversion of the gaseous constituents of the exhaust gas and a filtering-out of partkulates from the exhaust gas take place in a honeycomb body. 14. The method as claimed in claim 13, wherein the conversion of the gaseous constitutes of the exhaust gas takes place upstream of the filtering-out of participates with respect to a main direction of flow through the exhaust gas filter (11). 15. The method as claimed in one of claims 13 or 14, wherein the conversion of the gaseous particulates is catalyzed by at least one catalyst, preferably a noble metal catalyst. This invention relates to an exhaust gas filter (11) for cleaning an exhaust gas of an internal combustion engine, formed by at least one strip-shaped filter layer (1) with at least one filter region (2) made of material through which a fluid can at least partly flow and, for example, a metal foil (4). The filter layer (1) has at (east one contact region (3) with a catalytIcally active coating for the conversion of gaseous components of the exhaust gas and a filter region (2) for filtering out particulates from the exhaust gas.

Documents:

00119-kolnp-2005 abstract.pdf

00119-kolnp-2005 claims.pdf

00119-kolnp-2005 correspondence.pdf

00119-kolnp-2005 description(complete).pdf

00119-kolnp-2005 drawings.pdf

00119-kolnp-2005 form-1.pdf

00119-kolnp-2005 form-18.pdf

00119-kolnp-2005 form-2.pdf

00119-kolnp-2005 form-3.pdf

00119-kolnp-2005 form-5.pdf

00119-kolnp-2005 g.p.a.pdf

00119-kolnp-2005 letters patent.pdf

00119-kolnp-2005 priority document.pdf

00119-kolnp-2005 reply f.e.r.pdf

119-KOLNP-2005-FORM 27.pdf

119-KOLNP-2005-FORM-27.pdf

119-kolnp-2005-granted-abstract.pdf

119-kolnp-2005-granted-claims.pdf

119-kolnp-2005-granted-correspondence.pdf

119-kolnp-2005-granted-description (complete).pdf

119-kolnp-2005-granted-drawings.pdf

119-kolnp-2005-granted-form 1.pdf

119-kolnp-2005-granted-form 18.pdf

119-kolnp-2005-granted-form 2.pdf

119-kolnp-2005-granted-form 3.pdf

119-kolnp-2005-granted-form 5.pdf

119-kolnp-2005-granted-gpa.pdf

119-kolnp-2005-granted-letter patent.pdf

119-kolnp-2005-granted-reply to examination report.pdf

119-kolnp-2005-granted-specification.pdf

119-kolnp-2005-granted-translated copy of priority document.pdf