DE102017204089A1 - SCR catalyst system and method for its diagnosis - Google Patents

Abstract

The invention relates to a method for the diagnosis of an SCR catalyst system comprising the following steps: detecting (100) operating state data of a pump of a conveyor module and / or a dosing module of the SCR catalytic converter system, wherein both existing operating state data stored in a cloud memory, as well as current operating state data, which are detected by a control unit of the pump of the delivery module and / or the dosing, are detected. The already existing operating state data is compared with the current operating state data of the pump of the conveyor module and / or of the dosing module (120). Further, based on the comparison (120) of the already existing operating state data with the current operating state data, it is determined (130) whether the pump of the conveyor module and / or the dosing module are functioning properly or if maintenance is necessary.
Further, the invention relates to the SCR catalyst system for the exhaust gas of an internal combustion engine, which is adapted to perform the aforementioned method. The SCR catalyst system has a storage tank for storing a reducing agent to be metered into an exhaust line of the internal combustion engine, wherein the storage tank is connected to the metering module arranged on an exhaust pipe via the delivery module having the pump, and wherein the control unit of the SCR catalyst system is arranged such that that it is connectable to the cloud storage.

Description

The present invention relates to a method for diagnosing an SCR catalyst system. Furthermore, the present invention relates to an SCR catalyst system for carrying out the method. Furthermore, the invention relates to a computer program that performs each step of the method when it runs on a computing device, and a machine-readable storage medium that stores the computer program. Finally, the invention relates to an electronic control unit which is set up to carry out the method.

State of the art

In order to meet the increasingly stringent exhaust gas legislation particularly for motor vehicles, it is necessary to reduce the content of nitrogen oxides (NO _x ) in the exhaust gas of internal combustion engines. For this purpose, SCR catalysts (Selective Catalytic Reduction) are known which are arranged in the exhaust gas region of an internal combustion engine, wherein the SCR catalysts reduce the nitrogen oxides contained in the exhaust gas of the internal combustion engine in the presence of a reducing agent to nitrogen. For the course of the reaction, ammonia (NH ₃ ) is needed as a reducing agent or reagent, which is admixed to the exhaust gas. For the supply of ammonia usually under the name AdBlue ^® commercially available urea-water solution (HWL) is used, which consists of a third of urea as Ammoniaabspaltendem reagent and two-thirds of water.

A nozzle sprays the liquid into the exhaust stream immediately before an SCR catalyst. There, the urea forms the ammonia (NH ₃ ) necessary for the further reaction. In the SCR catalytic converter, nitrogen oxides from the exhaust gas and the ammonia combine to form water and non-toxic nitrogen. The efficiency of the SCR catalyst depends on the temperature, the space velocity and, crucially, its ammonia level.

Disclosure of the invention

The method is used to operate an SCR catalyst system, in particular the diagnosis of the SCR catalyst system. Diagnosis is an error detection in which it is examined whether the SCR catalyst system, in particular a pump of a delivery module and / or a metering module of the SCR catalyst system, requires maintenance.

The method comprises the following steps. In a first step, operating state data of the SCR catalyst system, in particular a pump of a delivery module and / or a metering module of the SCR catalyst system, are detected. In this case, both existing operating state data, which are stored in a cloud memory, as well as current operating state data, which are detected by a control unit of the pump of the conveyor module and / or the dosing, detected.

Operating state data can be understood as any physical variable measurable in the SCR catalyst system, which can characterize an operating state of the SCR catalyst system. In particular, the operating state data of the SCR catalyst system is the operating state data of the components of the SCR catalyst system.

There are two types of operating status data. These are on the one hand the already existing operating status data and on the other hand the so-called current operating status data. The already existing operating state data is stored in a cloud memory. Such cloud storage is also referred to as the automotive cloud. The cloud storage includes information about operating conditions of the components of the SCR catalyst system under various working conditions and from different car makes with different configurations. In addition to the already existing operating state data, there is the concept of the current operating state data, which may include all operating state data of the considered SCR catalyst system, in particular all operating state data of the components of the SCR catalyst system.

In general, the already existing operating state data includes substantially more data than the current operating state data, since the latter relates only to the particular SCR catalyst system of a specific internal combustion engine, which is usually arranged in a specific vehicle. On the other hand, the already existing operating state data relates to all possible different SCR catalyst systems and therefore also includes a multiplicity of different operating state data from all possible components of these SCR catalyst systems.

In a second step of the method, the already existing operating state data is compared with the current operating state data of the SCR catalytic converter system, in particular the pump of the conveyor module and / or of the dosing module. Such a comparison may relate to any information of the operating status data.

In particular, statistical data of the operating state data can also be compared with one another. By statistical data is meant, for example, an average value, a standard deviation, an expected value of a specific physical quantity or correlations of different measured values. The use of correlations makes it possible to make comparisons for a physical quantity existing only in the current operating state data or the already existing operating state data.

In the case of a first physical quantity occurring only in the already existing operating state data but not in the current operating state data, for example, a second physical quantity of the current operating state data having a known correlation with the first physical quantity of the current operating state data may be used to estimate a correlation of the first physical quantity of the already existing operating state data with the first physical quantity of the current operating state data.

In a third step of the method, based on the comparison of the already existing operating state data with the current operating state data, it is determined whether the SCR catalyst system, in particular the pump of the conveyor module and / or the dosing module, is functioning properly or if maintenance is necessary. For the comparisons to be carried out, rules are defined under which circumstances a component of the SCR catalyst system, in particular the pump of the delivery module and / or the metering module, functions properly. Additionally or alternatively, rules may be established when a component of the SCR catalyst system requires maintenance.

The method has the advantage that the diagnosis of when a component of the SCR catalyst system requires maintenance, due to the enormous wealth of statistical data stored in the cloud storage can be done much more accurately than in an SCR catalyst system, which only on The data supplied to the SCR catalyst system itself can be accessed.

According to a preferred embodiment, a component of the SCR catalyst system then requires maintenance if the comparison described in the second step has revealed that a specific physical measured value of the current operating state data differs from the already existing operating state data by more than a predetermined value. Predictable values include: 200%, 150%, 100%, 60%, 30%, 20%, 10%, 5%, 3%, 2% and 1%. Depending on the physical measured value used, different predefined values result for the above-mentioned difference. This embodiment has the advantage that for each physical measurement value only a predetermined value, which depends on the already existing operating state data, has to be compared with the physical measurement value of the current operating state data in order to find out when maintenance is necessary.

The operating state data preferably also includes the operating state data of an exhaust gas line. The operating state data of the exhaust gas line can, for example, i.a. a temperature of the exhaust gas at a certain point in the exhaust system or a concentration of a certain gas at a certain point in the exhaust system. This has the advantage that also the data of the exhaust gas can be used to more accurately characterize the SCR catalyst system.

According to one embodiment, it is preferred that the already existing operating state data has not been detected by the control device of the SCR catalytic converter system, in particular not by a control device of the conveyor module and / or by a control device of the dosing module. It is thereby achieved that, for the comparison of the already existing operating state data with the current operating state data, the already existing operating state data is not influenced by the current operating state data.

It is further preferred that the already existing operating state data for different types of motor vehicles and for the components of the SCR catalyst system have typical operating state data. Among other things, the term vehicle type also means different configurations of one and the same model of a motor vehicle. Under typical operating state data, statistics and ranges of values that are considered typical are also understood. It is thereby achieved that the already existing operating state data have reliable and accurate statistics on SCR catalyst systems which are familiar in practice.

According to a preferred embodiment, the operating state data of the pump of the delivery module include, among others, at least one of the following: suction, pumping speed, a time required for the pressure to reach a predetermined level, a pressure versus time course, and the pressure derived therefrom Sizes, a current that the pump requires as a function of time, a total current that the pump needs to build up a given pressure, parameters or characteristics that the Power to the pump, a funded amount of fluid as a function of time, a number of system starts, a number of operating hours, a pressure buildup time at startup, an operating temperature of the delivery module, a funded amount of liquid based on a duty cycle of the applied pump motor drive against time and a Duty cycle of the pump motor as a function of the flow rate, especially at vanishing flow rate. An advantage of this embodiment is that the said operating state data of the pump of the delivery module reliably characterize these.

By a derived quantity of the course of the pressure as a function of time, inter alia, a minimum, a maximum, any other statistical measure or another variable which can be calculated from said function is understood.

According to a preferred embodiment, the operating state data of the metering module of the SCR catalyst system includes at least one of the following quantities: a metering amount based on a duty cycle of the applied pump motor drive versus time, a metering frequency, a number of operating hours and an operating temperature of the metering module. An advantage of this embodiment is that said operating state data reliably characterizes the dosing module of the SCR catalyst system.

According to a further embodiment, it is preferred for the pump of the delivery module and / or for the dosing module to determine a degree of wear based on a comparison of at least one physical quantity of the current operating state data and the already existing operating state data. This embodiment has the advantage that, by calculating a degree of wear, the present SCR catalyst system characterized by the current operating condition data, in a simple manner with a expected state of a standard SCR catalyst system, which by the already existing Operating state data is characterized, can be compared. Here, the comparison is a simple comparison of two numbers, namely the levels of wear of the corresponding SCR catalyst systems.

According to a further preferred embodiment, the comparison of the already existing operating state data with the current operating state data of the pump of the conveyor module and / or the dosing takes place by the pump for the conveyor module and / or for the dosing module based on at least one physical size of the current operating state data, a degree of Wear is detected. This embodiment has the advantage that, to calculate the degree of wear, it is not necessary to access a cloud storage, but only data from the present SCR catalyst system is used.

If the degree of wear of the pump of the delivery module and / or the metering module of the SCR catalyst system, which corresponds to the at least one physical quantity of the current operating state data, greater than expected for the SCR catalyst system degree of wear of the pump of the delivery module and / or Dosing is, it is determined according to a preferred embodiment, that maintenance is required, otherwise a maintenance is postponed to a later date. This has the advantage that the time at which maintenance of the SCR catalyst system is to be carried out is adapted to the current operating state data of the SCR catalyst system.

According to an alternative embodiment, if the degree of wear of the pump of the delivery module and / or the metering module of the SCR catalyst system corresponding to the at least one physical quantity of the current operating condition data is greater than a threshold for the degree of wear of the pump of the delivery module and / or the dosing module determines that maintenance is required, otherwise maintenance will be postponed to a later date. The threshold value is preferably calculated on the basis of the already existing operating state data. This embodiment has the advantage that only one value, namely the threshold for the degree of wear, has to be compared with the physical measured value of the current operating state data in order to find out when maintenance is necessary.

Here, the expected degree of wear for a component of the SCR catalyst system corresponding to the at least one physical quantity of the current operating condition data is determined as follows. On the basis of the already existing operating state data in the cloud memory, an expected value for the at least one physical variable of the current operating state data is calculated. For this calculation, specific characteristics of the SCR catalyst system, such as the vehicle model or the operating hours of the components of the SCR catalyst system, are taken into account.

According to a preferred embodiment, in the event that maintenance is postponed to a later date, a period of time through a comparison of the current operating state data with the already existing operating state data. Here, based on the comparison of the current operating state data with the already existing operating state data, it is calculated when a certain component of the SCR catalytic converter system is likely to require maintenance. This calculation can also be performed for several or all components of the SCR catalyst system. This prevents unwanted failures of the motor vehicle and makes it possible to replace the faulty component at the next maintenance before it fails. Furthermore, the maintenance intervals can be planned dynamically if the components have little or no signs of wear.

It is further preferred that the time period until the next maintenance be recalculated each time the SCR catalyst system is started. It is further preferred that the time period until the next maintenance during operation of the SCR catalyst system is adapted dynamically to the current operating state data of the SCR catalyst system. This has the advantage that during operation of the SCR catalyst system, the time until the next maintenance is always up to date.

It is further preferred that the current operating state data for the pump of the conveyor module and / or for the metering module are at least partially, preferably completely, loaded into the cloud memory. This has the advantage that the already existing operating state data is updated. This is particularly important for SCR catalyst systems operating, for example, in new vehicles or under conditions for which there are few operating condition data. The thus updated already existing operating state data can be used in a subsequent evaluation, be it from the present SCR catalyst system or from another user of the cloud memory.

According to one embodiment, the pump of the delivery module is a delivery pump, which is preferably designed as a diaphragm pump. It is further preferred that the delivery module has a return pump. This has, inter alia, the advantage that the reducing agent can be promoted not only to the SCR catalyst, but also excess reducing agent can be fed back.

Another aspect of the invention relates to an SCR catalyst system for the exhaust gas of an internal combustion engine, which is configured to carry out the method described above. This SCR catalytic converter system has a storage tank for storing a reducing agent to be metered into an exhaust pipe of the internal combustion engine, wherein the storage tank is connected to a metering module arranged on the exhaust pipe via a delivery module having a pump. Furthermore, the SCR catalyst system has a control unit of the SCR catalyst system, which is set up so that it can be connected to a cloud storage. The SCR catalyst system, like the method, also has the advantage that the diagnosis of when a component of the SCR catalyst system requires maintenance can be much more accurate than with an SCR catalyst system because of the enormous wealth of statistical data stored in the cloud memory which can only access the data supplied by the SCR catalyst system itself.

The invention can be used in particular in SCR exhaust aftertreatment systems, which are used inter alia in gasoline engines or diesel engines of motor vehicles. However, it will be understood that the method also applies to other SCR exhaust aftertreatment systems of corresponding non-automotive internal combustion engine engines, e.g. in the field of marine engineering or in the field of chemical engineering, with the advantages described herein can be applied.

The computer program is set up to perform each step of the method, especially when it is performed on a computing device or controller. It allows the implementation of the method in a conventional electronic control unit without having to make any structural changes. For this purpose it is stored on the machine-readable storage medium.

By loading the computer program onto a conventional electronic control unit, the electronic control unit is set up, which is set up to operate an SCR catalytic converter by means of the method.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

list of figures

• 1 zeigt schematisch ein SCR-Katalysatorsystem, das mittels eines Verfahrens gemäß einem Ausführungsbeispiel der Erfindung betrieben werden kann.
• 2 und 3 zeigen jeweils eine schematische Darstellung eines Verfahrens gemäß einer Ausführungsform der Erfindung.

Embodiments of the invention are illustrated in the drawings and in the explained in more detail below description. In each case, in schematic form:

• 1 schematically shows an SCR catalyst system that can be operated by a method according to an embodiment of the invention.
• 2 and 3 each show a schematic representation of a method according to an embodiment of the invention.

Embodiments of the invention

In 1 is an SCR catalyst system 10 with a dosing device for dosing urea water solution (HWL) 12 in the exhaust system 10 an only indicated internal combustion engine 14 a motor vehicle shown. The SCR catalyst system 10 serves in a conventional manner for the reduction of nitrogen oxides in the exhaust gas of the internal combustion engine 14 by selective catalytic reduction (SCR). For the reduction is as reducing agent HWL 12 via a metering valve 16 a dosing module 17 in an exhaust system 18 upstream of the SCR catalyst 20 and downstream of an oxidation catalyst 22 injected.

The HWL 12 is in a storage tank 24 stored, which a level sensor 26 and a temperature sensor 28 each having a control unit 29 are connected. The metering valve 16 of the dosing module 17 is by means of a conveyor module 30 from the storage tank 24 with the HWL 12 provided. The delivery module has a compressed air line 38 that of a compressor 40 with an air storage 42 is fed.

The conveyor module 30 has a feed pump 32 on, by means of a suction line 34 HWL 12 from the storage tank 24 extracts. The HWL 12 is through a pressure line 36 to the metering valve 16 of the dosing module 17 directed. By means of this metering valve 16 becomes the HWL 12 between the internal combustion engine 14 and the SCR catalyst 20 in the exhaust system 18 injected.

The pump 32 and the dosing module 17 are from the electronic control unit 29 controlled. An exhaust gas temperature sensor 44 and an exhaust gas sensor 46 which are both downstream of the SCR catalyst 20 are arranged, are also connected to the electronic control unit 29 connected.

The control unit 29 of the SCR catalyst system 10 is with a cloud storage 48 wirelessly connected. This wireless connection is in 1 by a dashed line and two wireless symbols between the controller 29 of the SCR catalyst system 10 and the cloud storage 48 shown. Further, the controller 29 set up the SCR catalyst system 10 , especially the pump 32 of the conveyor module 30 and the dosing module 17 of the SCR catalyst system 10 to operate by means of the method according to the invention.

2 shows a schematic flow diagram of an embodiment of the method according to the invention for the diagnosis of the SCR catalyst system 10 ,

In step 100 become operating state data of the pump 32 the conveyor module 30 and / or the metering module 17 of the SCR catalyst system 10 detected. Capturing the step 100 this includes both existing operating state data, which in the cloud storage 48 are stored, as well as current operating state data, which from the control unit 29 the pump 32 of the conveyor module 30 and / or the dosing module 17 be recorded.

In a subsequent step 110 Additional operating state data of the exhaust system 18 detected. In this case, the exhaust gas temperature sensor supply 44 and the exhaust gas sensor 46 the corresponding data of the exhaust system 18 ,

Capturing the step 100 This includes both existing operating status data of the exhaust system 18 which are in the cloud store 48 are stored, as well as current operating state data of the exhaust system 18 that of the control unit 29 of the SCR catalyst system 10 be recorded.

The following will be in the step 120 existing operating status data with the current operating status data of the pump 32 of the conveyor module 30 and / or the dosing module 17 compared.

In the next step 130 is determined based on the comparison of the existing operating state data with the current operating state data, whether the pump 32 of the conveyor module 30 and / or the dosing module 17 work properly or whether maintenance is necessary.

If in step 130 has been determined that maintenance is necessary, the method goes to step 140 in which the diagnostic result indicates that maintenance is necessary.

If in step 130 was determined that no maintenance is necessary, the method goes to step 150 with a query, if a maintenance interval has expired. If the maintenance interval has expired, the procedure goes to step 140 next and shows as a diagnostic result that maintenance is necessary. If the maintenance interval has not yet expired, the procedure goes to step 160 and shows as a diagnostic result that no maintenance is necessary. Further, in this step, it is calculated based on a comparison of the current operation inventory data with the already existing operation status data when a next maintenance is to be performed.

3 shows a schematic flow diagram of another embodiment of the method according to the invention for the diagnosis of an SCR catalyst system.

In step 101 become already existing operating state data of the pump 32 of the conveyor module 30 and / or the dosing module 17 of the SCR catalyst system 10 which are in the cloud store 48 are stored, recorded. In the following step 102 Current operating state data from the controller 29 the pump 32 of the conveyor module 30 and / or the dosing module 17 read.

In a subsequent step 110 Additional operating state data of the exhaust system 18 detected. Capturing the step 100 This includes both existing operating status data of the exhaust system 18 which are in cloud storage 48 are stored, as well as current operating state data of the exhaust system 18 , which from the control unit 29 of the SCR catalyst system 10 are detected.

After that, in step 111 the current operating state data for the pump 32 of the conveyor module 30 , for the dosing module 17 and for the exhaust system 18 in the cloud store 48 loaded.

In the next step 121 will for the pump 32 of the conveyor module 30 and for the dosing module 17 determines a degree of wear based on a comparison of a predetermined number of physical quantities of the current operating state data and the already existing operating state data. Thus, one obtains a degree of wear of the pump and a degree of wear of the dosing. A physical size of the pump 32 of the conveyor module 30 For example, it may be the pumping speed.

In a subsequent step 122 Due to the operating state data already existing in the cloud memory, the degree of pump wear expected for the SCR catalyst system 10 is expected 32 of the conveyor module 30 and the dosing module 17 calculated.

In a next step 123 be the degree of wear of the pump 32 of the conveyor module 30 and the degree of wear of the dosing module 17 which in step 121 were determined, with the expected degree of wear of the pump 32 of the conveyor module 30 and expected degree of wear of the dosing module 17 compared. If for the pump 32 of the conveyor module 30 or for the dosing module 17 the degree of wear is greater than the expected degree of wear, the method goes to step 140 in which the diagnostic result indicates that maintenance is necessary.

As an alternative to an expected degree of wear, a threshold may also be used, which may be e.g. 90% of a wear value is.

If for the pump 32 of the conveyor module 30 and for the dosing module 17 If the degree of wear is less than the expected degree of wear, the method continues in step 150 with a query, if a maintenance interval has expired. If the maintenance interval has expired, the procedure goes to step 140 next and shows as a diagnostic result that maintenance is necessary. If the maintenance interval has not yet expired, the procedure goes to step 160 and shows as a diagnostic result that no maintenance is necessary. Further, in this step, it is calculated based on a comparison of the current operation inventory data with the already existing operation status data when a next maintenance is to be performed.

Claims (14)

Method for the diagnosis of an SCR catalyst system (10) with the following steps: a. Detecting (100) operating state data of a pump (32) of a conveyor module (30) and / or a dosing module (17) of the SCR catalyst system (10), wherein both existing operating state data stored in a cloud memory (48), as well as current operating state data, which are detected by a control unit (29) of the pump (32) of the conveyor module (30) and / or the dosing module (17) are detected; b. Comparing (120) the already existing operating state data with the current operating state data of the pump (32) of the conveyor module (30) and / or the dosing module (17); and c. based on comparing (120) the already existing operating state data with the current operating state data determining (130), whether the pump (32) of the conveyor module (30) and / or the dosing module (17) are functioning properly or if maintenance is necessary. Method according to Claim 1 , characterized in that when detecting the operating state data of the pump (32) of the conveyor module (30) and / or the metering module (17) of the SCR catalyst system (10) additionally operating state data an exhaust line (18) are detected, wherein both existing operating state data of the exhaust line (18), which are stored in a cloud memory (48), as well as current operating state data of the exhaust system (18), which from a control unit (29) of the SCR -Catalyst system (10) are detected. Method according to Claim 1 or 2 , characterized in that the already existing operating state data, which are stored in a cloud memory (48), have not been detected by the control unit (29) of the conveyor module (30) and / or the dosing module (17). Method according to one of the preceding claims, characterized in that the already existing operating state data stored in a cloud memory (48) have typical operating state data for different motor vehicle types and for the components of the SCR catalytic converter system (10). Method according to one of the preceding claims, characterized in that the operating state data of the pump (32) of the delivery module (30) among others at least one of the following sizes: Suction, pump speed, a time required until the pressure reaches a predetermined level , a progression of the pressure as a function of time and variables derived therefrom, a current which the pump (32) requires as a function of time, a total current which the pump (32) requires to build up a predetermined pressure, parameters or parameters, relating to the power supply of the pump (32), a quantity of fluid delivered as a function of time, a number of system starts, a number of operating hours, a pressure build-up time, an operating temperature of the delivery module (30), a delivered amount of fluid based on a duty cycle the applied pump motor drive against time and a duty cycle d It pump motor as a function of flow, especially at vanishing flow rate. Method according to one of the preceding claims, characterized in that the operating state data of the dosing module (17) of the SCR catalyst system (10) include at least one of the following quantities: a dosing amount based on a duty factor of the applied pump motor drive over time, a dosing frequency, a number of operating hours and an operating temperature of the dosing module (17). Method according to Claim 5 or 6 , characterized in that the comparison (120) of the already existing operating state data with the current operating state data of the pump (32) of the conveyor module (30) and / or the dosing module (17) takes place by applying for the pump (32) of the conveyor module (30). and / or for the dosing module (17) a degree of wear is determined based on the comparison of at least one physical quantity of the current operating state data and the already existing operating state data. Method according to Claim 7 characterized in that if the degree of wear of the pump (32) of the delivery module (30) and / or the dosing module (17) of the SCR catalyst system (10) corresponding to the at least one physical quantity of the current operating condition data is greater than one for the SCR catalyst system (10) is expected degree of wear of the pump (32) of the conveyor module (30) and / or the dosing module (17), it is determined that maintenance is required, otherwise maintenance is deferred to a later date , Method according to Claim 8 characterized in that, in the case where maintenance is postponed to a later time, a period of time until a next maintenance is calculated based on a comparison of the current operating condition data with the already existing operating condition data. Method according to one of the preceding claims, characterized in that the current operating state data for the pump (32) of the conveyor module (30) and / or for the metering module (17) are at least partially loaded into the cloud memory (48). SCR catalyst system (10) for the exhaust gas of an internal combustion engine (14), which is arranged, a method according to one of Claims 1 to 10 comprising: a storage tank (24) for storing a reducing agent (12) to be metered into an exhaust line of the internal combustion engine (14), the storage tank (24) being connected via a pump (32) having a delivery module (30) to the exhaust pipe ( 18) arranged dosing module (17) is connected, and wherein a control device (29) of the SCR catalyst system (10) is arranged so that it is connectable to a cloud memory (48). Computer program, which is set up, each step of the procedure according to one of Claims 1 to 10 perform. Machine-readable storage medium on which a computer program according to the preceding claim is stored. Electronic control unit (29) which is set up, an SCR catalyst system (10), in particular a pump (32) of a delivery module (30) and / or a dosing module (17) of the SCR catalyst system (10), by a method according to one of the Claims 1 to 10 to operate.

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