Method for detecting an aging state of an exhaust aftertreatment component and exhaust aftertreatment system

Abstract

Method for detecting an aging state of an exhaust aftertreatment component in an exhaust system (20) of an internal combustion engine (10), comprising the following steps: - Recording aging-relevant parameters of an operating profile of the internal combustion engine (10), - Calculating the expected aging state of the exhaust aftertreatment component based on the recorded aging-relevant parameters, - Comparing the expected state of aging with the state of aging of the exhaust aftertreatment component at the end of its planned service life, and - Requesting replacement of the exhaust aftertreatment component if the expected state of aging of the exhaust aftertreatment component suggests that sufficient exhaust aftertreatment to comply with emissions legislation is no longer possible with the exhaust aftertreatment component, whereby - the aging-relevant parameters include a driving profile of a motor vehicle in which the internal combustion engine (10) is installed, wherein at least a driving speed as well as a number and duration of overrun phases of the internal combustion engine (10) are recorded in the driving profile.

Description

[0001] The invention relates to a method for detecting an aging state of an exhaust gas aftertreatment component in an exhaust system of an internal combustion engine and to an exhaust gas aftertreatment system for carrying out such a method.

[0002] Current emissions legislation, which will become increasingly stringent in the future, places high demands on raw engine emissions and exhaust aftertreatment in internal combustion engines. The demands for further reduced fuel consumption and the further tightening of emissions standards regarding permissible nitrogen oxide emissions pose challenges for engine developers. In gasoline engines, exhaust gas purification is achieved in the usual way via a three-way catalytic converter, as well as additional catalysts upstream and downstream of the three-way catalytic converter. Diesel engines currently use exhaust aftertreatment systems that include an oxidation catalyst or a NOx storage catalyst, a catalyst for the selective catalytic reduction of nitrogen oxides (SCR catalyst), a particulate filter for the separation of soot particles, and possibly additional catalysts.

[0003] Coating catalysts with precious metals is a significant cost factor for exhaust aftertreatment systems in combustion engines. The catalysts are typically designed to efficiently convert pollutants in the exhaust stream of a passenger car over the planned service life of approximately 200,000 km.

[0004] The mining and extraction of precious metals requires considerable effort and is associated with corresponding environmental impacts. Given the average mineralization grades of mines that extract platinum group metals such as platinum, palladium, and rhodium, more than a ton of rock must be mined to extract 1 gram of a platinum group metal. Furthermore, extracting the platinum group metal from the mined rock is laborious and associated with significant environmental impacts.

[0005] US 2016 / 0 216 174 A1 discloses a diagnostic device for diagnosing a particulate filter, which comprises an exhaust pipe with an outer wall, wherein the outer wall of the exhaust pipe defines an enclosure, wherein the enclosure has the smallest possible tubular enclosure with a circular cross-section that is coplanar with the cross-section of the exhaust pipe and surrounds the outer wall of the exhaust pipe at every point along the exhaust pipe. The diagnostic device further comprises an exhaust chamber with a detection filter, and a temperature sensor arranged in the exhaust chamber for measuring an exhaust gas temperature.

[0006] WO 2021 / 097655 A1 discloses an exhaust aftertreatment system for a diesel engine comprising an exhaust aftertreatment component, a sensor, and a control unit. The exhaust aftertreatment component comprises a housing with an air distribution mechanism that can control the exhaust flow into two different chambers. An oxidation catalyst and a particulate filter are arranged in one of the chambers. The control unit monitors the distribution of the exhaust flow and the exhaust backpressure.

[0007] From US 2014 / 0 044 632 A1 an exhaust gas aftertreatment system for an internal combustion engine, in particular for an internal combustion engine or a turbine, is known, wherein the exhaust gas aftertreatment system has one or more modules, wherein at least one module is designed to remove carbon dioxide from the exhaust gas flow of the internal combustion engine.

[0008] DE 196 51 559 A1 discloses a method for controlling an internal combustion engine. An estimate of catalyst deterioration is made in a catalytic treatment device for engine exhaust gases, which includes ignition timing control, intake air control, and supplemental catalyst heating control. The estimate of the deterioration is responsive to a catalyst temperature estimate, which can be corrected according to the estimated deterioration.

[0009] DE 10 2012 104 669 A1 discloses a method for operating an exhaust system of an internal combustion engine, which comprises at least one heating device and a catalyst for converting unburned hydrocarbons. The heating device is operated in a manner adapted to the aging state of the catalyst.

[0010] EP 1 201 900 B1 discloses a control method for an internal combustion engine with an exhaust gas catalytic converter, in which the degree of aging of the catalytic converter is detected, and in which the internal combustion engine can be operated in at least two operating modes. One operating mode is more emission-efficient. A transition from one operating mode of the internal combustion engine to another operating mode is selected depending on the aging state of the catalytic converter. It is provided that the operating modes comprise homogeneous and stratified operation, wherein operation with a homogeneous air / fuel distribution at the start of the vehicle is selected for a longer period depending on the aging state of the catalytic converter, and only after a period of time dependent on the aging state of the catalytic converter does the engine transition to stratified operation.

[0011] Furthermore, DE 102 10 550 A1 discloses a method for operating an internal combustion engine, in particular a lean-burn, direct-injection gasoline engine, in which an exhaust gas from the internal combustion engine flows through an exhaust catalyst. During warm-up or a low-load operating point of the internal combustion engine, an engine control unit adjusts an operating parameter of the internal combustion engine depending on the aging state of the exhaust catalyst.

[0012] The invention is based on the object of minimizing the use of rare and expensive catalyst materials and nevertheless always being able to ensure efficient conversion of the pollutants in the exhaust stream of the combustion engine.

[0013] According to the invention, this object is achieved by a method for detecting an aging state of an exhaust aftertreatment component in an exhaust system of an internal combustion engine, which method comprises the following steps: - Recording of age-relevant parameters of an operating profile of the combustion engine, - Calculating an expected ageing state of the exhaust aftertreatment component based on the recorded ageing-relevant parameters, - comparing the expected ageing state with an ageing state of the exhaust aftertreatment component at the end of the planned service life of the exhaust aftertreatment component, - Replacement of the exhaust aftertreatment component if the expected aging of the exhaust aftertreatment suggests that adequate exhaust aftertreatment by the exhaust aftertreatment component is no longer possible.

[0014] Exhaust aftertreatment components of internal combustion engines, particularly those in passenger cars, are generally designed to enable efficient conversion of pollutants generated during fuel combustion in the combustion chambers of the internal combustion engine over their entire planned service life. To ensure and sustain such conversion even under adverse conditions, comparatively large quantities of catalytically active materials, particularly precious metals, are required to coat the exhaust aftertreatment components. In most applications, the internal combustion engine is operated with a load profile that allows efficient conversion with smaller quantities of the catalytically active material.

[0015] The proposed method enables the use of exhaust aftertreatment components with significantly lower quantities of catalytically active materials, thus significantly reducing the environmental impact of extracting the catalytically active materials. Furthermore, reducing the often expensive catalytically active materials leads to a reduction in the manufacturing costs for the exhaust aftertreatment components, making the entire exhaust aftertreatment system more cost-effective to manufacture. In exhaust systems subject to an unfavorable load profile of the combustion engine, one or more exhaust aftertreatment components must then be replaced. Such a replacement is detected in a timely manner by the method according to the invention, reliably preventing an increase in tailpipe emissions due to insufficiently efficient exhaust aftertreatment.

[0016] The features listed in the dependent claims enable advantageous improvements and further developments of the method listed in the independent claim for detecting an aging state of exhaust gas aftertreatment components.

[0017] In a preferred embodiment of the invention, aging-relevant parameters are continuously recorded during operation of the internal combustion engine. Continuously recording these parameters allows for a better estimate of the aging of the exhaust aftertreatment component, since individual operating points that result in particularly rapid or severe aging of the exhaust aftertreatment component are also adequately taken into account.

[0018] In a further preferred embodiment of the invention, the aging-relevant parameters include an exhaust gas mass flow and / or an exhaust gas temperature of the internal combustion engine. By continuously recording the exhaust gas temperature and / or the exhaust gas mass flow, it is possible to estimate how much heat is introduced into an exhaust gas aftertreatment component and what the thermal load for this exhaust gas aftertreatment component is. Not only high peak temperatures, but also rapid changes between high exhaust gas temperatures and low exhaust gas temperatures can lead to accelerated aging of the exhaust gas aftertreatment component. By combined recording of exhaust gas temperature and exhaust gas mass flow, the accuracy in determining the thermal peak load and / or thermal cycling load can be improved.

[0019] In a preferred embodiment of the invention, the aging-relevant parameters include the number of operating hours of the internal combustion engine and / or the mileage of a motor vehicle in which the internal combustion engine is installed. The aging of the exhaust gas aftertreatment component is significantly influenced by the operating time of the internal combustion engine and the required power of the internal combustion engine. Alternatively, the mileage of a motor vehicle in which the internal combustion engine is installed can also be considered a measure of aging. Thus, the mileage of a motor vehicle or the operating hours of the internal combustion engine, particularly in conjunction with other parameters, can provide an important parameter for estimating the aging of the exhaust gas aftertreatment component.

[0020] Additionally or alternatively, the aging-relevant parameters can include the type of fuel burned in the combustion engine and / or the quality of the burned fuel. In this context, the "fuel type" refers to the different fuel grades (E5, E10, Super Plus), while the "fuel grade" refers to the regional differences, particularly between the same fuel types. Fuels differ not only in their energy content, but also in the presence of additives and contaminants. Thus, some combustion engines require gasoline with at least 98 octane to deliver their full power. While these combustion engines can often be operated with lower fuel grades, they then suffer a loss of power or durability.Since higher maximum power of the combustion engine is generally associated with higher peak temperatures and / or higher exhaust gas temperatures, fuel quality and fuel type influence not only the maximum power but also the aging of the exhaust aftertreatment components. Furthermore, additives can counteract aging, and fuel contamination can lead to accelerated aging of the exhaust aftertreatment components. The fuel type and / or fuel quality can be determined, in particular, by a fuel sensor on a fuel tank from which the combustion engine is supplied with fuel.

[0021] According to the invention, the aging-relevant parameters include a driving profile of a motor vehicle in which the combustion engine is installed. By recording the driving profile, it is possible to estimate how quickly the exhaust aftertreatment components age and whether efficient exhaust aftertreatment can be expected over the service life of the vehicle even with a smaller amount of catalytically active material.

[0022] According to the invention, the driving speed of the motor vehicle and the number and duration of the overrun phases of the internal combustion engine are recorded. The driving speed of a motor vehicle and / or the number and duration of the overrun phases of the internal combustion engine are particularly crucial for the aging of the exhaust gas aftertreatment components. Based on the driving speed, a load profile of the internal combustion engine can be estimated, since high driving speeds directly correlate with high loads on the internal combustion engine. A high proportion of full load of the internal combustion engine, for example, leads to accelerated aging of the exhaust gas aftertreatment components. The overrun phases of the internal combustion engine have a damaging effect on the catalyst in several respects. Firstly, an oxygen reservoir of the catalyst, in particular a three-way catalyst, is filled during the overrun phase.This is an exothermic process in which the catalyst heats up. A hot catalyst, which is subjected to a superstoichiometric exhaust gas flow, can quickly convert a large amount of unburned hydrocarbons, carbon monoxide, and other oxidative exhaust gas components, thereby further increasing the temperature of the catalyst. Over the remainder of the overrun phase, the catalyst cools down again as it is flushed with fresh air that is compressed in the combustion chambers of the internal combustion engine. Once combustion resumes in the combustion chambers of the internal combustion engine, the filled oxygen reservoir with an excess of oxidative exhaust gas components must be partially emptied again. These mechanisms lead to steep temperature gradients and sometimes high peak temperatures, which promote aging of the catalyst.

[0023] In a further advantageous embodiment of the method, an exhaust gas sensor for on-board diagnostics of the exhaust gas aftertreatment components is arranged in the exhaust system. On-board diagnostics can ensure that the exhaust gas aftertreatment component has efficiently converted the pollutants. A sensor for on-board diagnostics thus offers additional safety, as a decrease in the conversion performance of the exhaust gas aftertreatment component is detected in a timely manner, allowing the exhaust gas aftertreatment component to be replaced to prevent an unacceptable increase in tailpipe emissions.

[0024] A further aspect of the invention relates to an exhaust aftertreatment system for an internal combustion engine, which comprises an exhaust system in which at least one exhaust aftertreatment component, preferably a plurality of exhaust aftertreatment components, is arranged. The exhaust aftertreatment system further comprises a control unit with a memory unit and a computing unit, as well as a machine-readable program code stored in the memory unit. The control unit is configured to execute a method according to the invention when the machine-readable program code is executed by the computing unit.

[0025] Such an exhaust aftertreatment system can reduce the costs of exhaust aftertreatment. Furthermore, resources for rare, expensive, and difficult-to-obtain catalyst materials, particularly platinum group precious metals, can be saved.

[0026] In an advantageous embodiment of the exhaust gas aftertreatment system, the exhaust gas aftertreatment component is a catalyst, wherein the catalyst is coated with a catalytically active material, in particular a noble metal, particularly preferably with a noble metal from the platinum group, wherein a decrease in the free surface area of ​​the catalytically active material is a measure of the aging of the exhaust gas aftertreatment component. Since the conversion performance depends significantly on the free surface area of ​​the catalytically active material and this is reduced over the service life of the exhaust gas aftertreatment component, the catalytically active surface area is a measure of the aging of the exhaust gas aftertreatment component. The catalytic effectiveness of a catalyst is reduced, for example, by sintering of the noble metals and the associated loss of the catalytically active surface area.Furthermore, the catalytic effectiveness can be reduced by deposits on the catalytic coating, as these deposits reduce the effective surface area. Furthermore, inclusions in a sintered washcoat of the catalyst, the discharge of washcoat material, or the formation of more flexible catalytically active alloys can also reduce the catalytic effectiveness of the catalyst. Such a reduction in catalytic effectiveness, in particular of the free catalytically active surface area, could lead to an increase in tailpipe emissions in the event of an age-related decrease. However, this is prevented by the method according to the invention, since such a decrease is detected in good time by a calculation model stored, for example, in the engine control unit of the internal combustion engine, and replacement of the catalyst is required before an increase in tailpipe emissions occurs.

[0027] The various embodiments of the invention mentioned in this application can be advantageously combined with one another, unless otherwise stated in the individual case.

[0028] The invention is explained below in exemplary embodiments with reference to the accompanying drawings. They show: Fig. 1 shows an internal combustion engine with an exhaust gas aftertreatment system and a control unit, wherein the control unit is configured to carry out a method according to the invention, Fig. 2 shows a further embodiment of an internal combustion engine with an exhaust gas aftertreatment system and a control unit for carrying out a method according to the invention, and Fig. 3 a flowchart for carrying out a method according to the invention for detecting an aging state of an exhaust gas aftertreatment component

[0029] Fig. Figure 1 shows an internal combustion engine 10 with four combustion chambers 12, which is designed as a spark-ignition internal combustion engine 10 based on the Otto cycle principle. A fuel injector 14 and a spark plug 16 for igniting a combustible fuel-air mixture are arranged at each of the combustion chambers 12.

[0030] The internal combustion engine 10 is connected by its outlet 18 to an exhaust system 20 comprising an exhaust duct 22 in which, in the flow direction of an exhaust gas flow from the internal combustion engine 10 through the exhaust duct, a turbine 26 of an exhaust gas turbocharger is arranged, downstream of the turbine 26 a close-coupled first catalyst 28, and downstream of the first catalyst 28 a second catalyst 30. The first catalyst 28 and the second catalyst are preferably designed as three-way catalysts 38. A particulate filter 48 can also be arranged downstream of the turbine 26 of the exhaust gas turbocharger 24.

[0031] Furthermore, a temperature sensor 40 and an exhaust gas sensor 50 are arranged in the exhaust system 20 to determine an exhaust gas temperature and monitor the pollutant concentration. The exhaust gas sensor 50 can be designed, in particular, as an HC sensor 52 for monitoring the concentration of unburned hydrocarbons or as a NOx sensor 54 for monitoring the concentration of nitrogen oxides in the exhaust duct 20. The exhaust gas sensors are preferably arranged downstream of an exhaust gas aftertreatment component in order to monitor the function of the exhaust gas aftertreatment component as part of an on-board diagnostic system.

[0032] Furthermore, one or more mass flow sensors 42 can be arranged in the exhaust system 20 and / or in an intake tract (not shown) of the internal combustion engine 10 to monitor the fresh air and / or exhaust gas mass flow. Furthermore, a fuel sensor 44 for detecting the fuel type and / or fuel quality can be arranged on a fuel tank from which the internal combustion engine 10 is supplied with fuel.

[0033] The internal combustion engine 10 is operatively connected to a control unit 60, which includes a memory unit 62 and a computing unit 64. A machine-readable program code 66 is stored in the memory unit 62, which implements a method according to the invention when the machine-readable program code 66 is executed by the computing unit 64.

[0034] Fig.Figure 2 shows another embodiment of an internal combustion engine 10 with an exhaust aftertreatment system. In this example, the internal combustion engine 10 is designed as a diesel engine with four combustion chambers 12. A fuel injector 14 is arranged at each combustion chamber 12 for injecting fuel into the corresponding combustion chamber 12.

[0035] The exhaust 18 of the internal combustion engine 10 is connected to an exhaust system 20 comprising an exhaust duct 22 in which, in the flow direction of an exhaust gas flow of the internal combustion engine 10 through the exhaust duct, a turbine 26 of an exhaust gas turbocharger is arranged, downstream of the turbine 26 a close-coupled first catalyst 28, and downstream of the first catalyst 28 a second catalyst 30 is arranged. The first catalyst 28 is preferably designed as an oxidation catalyst 32 or as a NOx storage catalyst 24 with an oxidation stage. The second catalyst 30 is preferably designed as an SCR catalyst 36, in particular as a particulate filter 46 with an SCR coating 48. Furthermore, further catalysts can be arranged in the exhaust system, in particular further catalysts for reducing the nitrogen oxide emissions of the internal combustion engine 10.

[0036] Furthermore, a temperature sensor 40 and an exhaust gas sensor 50 are arranged in the exhaust system 20 to determine an exhaust gas temperature and monitor the pollutant concentration. The exhaust gas sensor 50 can be designed, in particular, as an HC sensor 52 for monitoring the concentration of unburned hydrocarbons or as a NOx sensor 54 for monitoring the concentration of nitrogen oxides in the exhaust duct 20. The exhaust gas sensors are preferably arranged downstream of an exhaust aftertreatment component in order to monitor the function of the exhaust aftertreatment component as part of an on-board diagnostic system.

[0037] Furthermore, one or more mass flow sensors 42 can be arranged in the exhaust system 20 and / or in an intake tract (not shown) of the internal combustion engine 10 to monitor the fresh air and / or exhaust gas mass flow. Furthermore, a fuel sensor 44 for detecting the fuel type and / or fuel quality can be arranged on a fuel tank from which the internal combustion engine 10 is supplied with fuel.

[0038] The internal combustion engine 10 is operatively connected to a control unit 60, which includes a memory unit 62 and a computing unit 64. A machine-readable program code 66 is stored in the memory unit 62, which implements a method according to the invention when the machine-readable program code 66 is executed by the computing unit 64.

[0039] Diesel oxidation catalysts 32 preferably have a catalytically active coating made of a platinum group metal, in particular a platinum coating or a palladium coating. The catalytically active coating of a three-way catalyst 38 generally comprises a metal oxide such as aluminum oxide or zirconium oxide as a support material and a catalytically active coating made of one or more metals from the platinum group metals, in particular platinum, palladium, rhodium, or a combination of these precious metals, as well as a cerium oxide as an oxygen storage medium. Four-way catalysts, i.e., particulate filters 46 with a three-way catalytically active coating, have a similar coating, but are more susceptible to premature aging due to the carrier substrate.

[0040] Since platinum group metals, in particular, can only be extracted with great effort and represent the decisive cost factor for a catalyst, the focus is on environmentally friendly and cost-effective extraction of these precious metals. SCR catalysts 36 typically have a coating of titanium oxide, tungsten oxide, and vanadium oxide. Although these compounds are comparatively inexpensive compared to platinum group metals, their extraction requires considerable energy.

[0041] The method according to the invention for detecting an aging state of an exhaust gas aftertreatment component can reduce the use of these precious metals, thereby lowering the costs for the exhaust gas aftertreatment components and reducing the environmental impact of extracting these precious metals.

[0042] In a first step <100> Age-relevant parameters of an operating profile of the combustion engine 10 are recorded. In a subsequent process step <110> The expected aging state of the exhaust gas aftertreatment component, in particular a catalyst, is calculated from the recorded aging-relevant parameters. In one process step <120> The expected aging state of the exhaust aftertreatment component is compared with the aging state of the exhaust aftertreatment component at the end of the planned service life of the exhaust aftertreatment component. In one process step <130> The request to replace the exhaust gas aftertreatment component is made if the expected ageing of the exhaust gas aftertreatment component indicates that exhaust gas aftertreatment sufficient to meet the statutory emission requirements is no longer possible.

[0043] As a rule, emissions legislation can be met with a medium load profile, even with a smaller amount of catalytically active material over the lifetime of a motor vehicle. For example, a passenger car is assumed to have a life expectancy of 12 years or 240,000 km. Should unfavorable conditions lead to premature aging of the exhaust aftertreatment component, it will be replaced. The replacement time for the exhaust aftertreatment component can also be determined by a regular test during a scheduled workshop service. For this purpose, a defined procedure can be carried out in the workshop, whereby the current aging state of the exhaust aftertreatment component(s) is determined using appropriate measuring technology. The advantage is that stationary measuring technology generally has a higher measurement accuracy and such measurements are easier to reproduce, i.e.subject to lower random errors and measurement inaccuracies. Based on the measurement results, the time for a possible replacement of the exhaust aftertreatment component can then be determined. Alternatively or additionally, a forecast could be made as to whether the next service is sufficient to replace the exhaust aftertreatment component during this subsequent service. List of reference symbols 10 Combustion engine 12 combustion chamber 14 Fuel injector 16 Spark plug 18 Outlet 20 Exhaust system 22 exhaust duct 24 exhaust gas turbochargers 26 turbines 28 first catalyst 30 second catalyst 32 Oxidation catalyst 34 NOx storage catalyst 36 SCR catalyst 38 Three-way catalyst 40 Temperature sensor 42 Mass flow sensor 44 Fuel sensor 46 particle filters 48 SCR coating 50 exhaust gas sensor 52 HC sensor 54 NOx sensor 60 control unit 62 storage unit 64 computing unit 66 Program code

Claims

[1] Method for detecting an ageing state of an exhaust aftertreatment component in an exhaust system (20) of an internal combustion engine (10), comprising the following steps: - Recording age-relevant parameters of an operating profile of the combustion engine (10), - Calculating an expected ageing state of the exhaust aftertreatment component based on the recorded ageing-relevant parameters, - comparing the expected ageing state with an ageing state of the exhaust aftertreatment component at the end of the planned service life of the exhaust aftertreatment component, and - Request replacement of the exhaust aftertreatment component if the expected ageing of the exhaust aftertreatment component indicates that sufficient exhaust aftertreatment to meet emissions legislation is no longer possible with the exhaust aftertreatment component, whereby - the ageing-relevant parameters comprise a driving profile of a motor vehicle in which the internal combustion engine (10) is installed, wherein at least a driving speed and a number and duration of overrun phases of the internal combustion engine (10) are recorded in the driving profile. [2] Method according to claim 1, wherein the ageing-relevant parameters are continuously recorded during operation of the internal combustion engine (10). [3] Method according to claim 1 or 2, wherein the ageing-relevant parameters comprise an exhaust gas mass flow and / or an exhaust gas temperature of the internal combustion engine (10). [4] Method according to one of claims 1 to 3, wherein the ageing-relevant parameters comprise a number of operating hours of the internal combustion engine (10) and / or a mileage of a motor vehicle in which the internal combustion engine (10) is installed. [5] Method according to one of claims 1 to 4, wherein the ageing-relevant parameters comprise a type of fuel burned in the internal combustion engine and / or a quality of the burned fuel. [6] Method according to one of claims 1 to 5, wherein an exhaust gas sensor (50) for on-board diagnosis of the exhaust gas aftertreatment component is arranged in the exhaust system (20). [7] Exhaust gas aftertreatment system for an internal combustion engine (10), comprising an exhaust system (20) in which at least one exhaust gas aftertreatment component is arranged, and a control unit (60) with a memory unit (62) and a computing unit (64) and a program code (66) stored in the memory unit (62), wherein the control unit (60) is configured to carry out a method according to one of claims 1 to 6 when the program code (66) is executed by the computing unit (64). [8] Exhaust aftertreatment system according to claim 7, characterized byin that the exhaust gas aftertreatment component is a catalyst (28, 30, 32, 34, 36, 38), wherein the catalyst (28, 30, 32, 34, 36, 38) is coated with a catalytically active material, in particular with a noble metal, wherein a decrease in the free surface of the catalytically active material determines a measure of the aging of the exhaust gas aftertreatment component.

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