Method for performing an installation diagnosis of a catalytic converter of a motor vehicle, electronic computing device and motor vehicle

Abstract

The invention relates to a method for performing an installation diagnosis of a catalyst (14) of a motor vehicle, in which an actual oxygen storage capacity for a catalyst section (12) of an exhaust aftertreatment system (10) of the motor vehicle is determined by means of two oxygen sensors (20, 22), in which the catalyst (14) is installed during intended use, and is compared with a target oxygen storage capacity for the catalyst section (12) (V1), if it is determined that the actual oxygen storage capacity deviates from the target oxygen storage capacity by more than a predetermined threshold value: Determining whether a fault entry, which characterizes a fault of a motor vehicle component of the motor vehicle, has been created in a fault memory of the motor vehicle within a defined time interval extending into the past (V2), and if it is determined,that no fault entry has been created in the fault memory during the time interval: Determine that no catalyst (14) is installed in the catalyst area (12) (V3).

Description

[0001] The invention relates to a method for carrying out an installation diagnosis of a catalytic converter of a motor vehicle, an electronic computing device for a motor vehicle and a motor vehicle.

[0002] DE 10 2008 038 677 B4 discloses a method for diagnosing an exhaust gas catalytic converter. In the method, a first exhaust gas sensor signal from a first oxygen sensor arranged in an exhaust system upstream of the exhaust gas catalytic converter is detected. Furthermore, a second exhaust gas sensor signal from a second oxygen sensor arranged in the exhaust system downstream of the exhaust gas catalytic converter is detected. In the method, a first estimated value of an emission and a second estimated value of an emission of at least one of the exhaust gas components carbon monoxide, nitrogen oxide, or hydrocarbon are determined using an emissions model with respect to a position of the respective oxygen sensors in the exhaust system as a function of the respective exhaust gas sensor signal assigned to the oxygen sensor.In the method, a conversion rate of the at least one exhaust gas component is further estimated depending on a ratio of the second and the first estimated value of the determined emission and the exhaust gas catalyst is diagnosed depending on the determined conversion rate.

[0003] The object of the present invention is to provide a solution by means of which it can be reliably determined whether a catalytic converter is installed in a motor vehicle or not.

[0004] This object is achieved according to the invention by the subject matter of the independent claims. Further possible embodiments of the invention are described in the

[0005] Subclaims, the description, and the figures. Features, advantages, and possible embodiments set forth in the description for one of the subject-matter of the independent claims are to be regarded, at least analogously, as features, advantages, and possible embodiments of the respective subject-matter of the other independent claims, as well as any possible combination of the subject-matter of the independent claims, optionally in conjunction with one or more of the subclaims.

[0006] The invention relates to a method for carrying out an installation diagnosis of a catalytic converter of a motor vehicle. The catalytic converter is used for exhaust gas aftertreatment in motor vehicles with internal combustion engines. The catalytic converter can drastically reduce pollutant emissions in the exhaust gas. The task of the catalytic converter is the chemical conversion of the combustion pollutants hydrocarbons, carbon monoxide and nitrogen oxides into the non-toxic substances carbon dioxide, water and nitrogen by oxidation or reduction. The method provides that by means of two oxygen sensors, one of which is arranged upstream and the other downstream of a catalytic converter region, an actual oxygen storage capacity for the catalytic converter region is determined and compared with a target oxygen storage capacity for the catalytic converter region. At least part of the catalytic converter system in the motor vehicle is usually installed in this catalytic converter region.The oxygen sensors can be, for example, so-called lambda sensors. The first oxygen sensor is arranged in an exhaust gas aftertreatment system of the motor vehicle at a position which, when the catalytic converter is installed as intended, is downstream of the catalytic converter. In other words, the first oxygen sensor is arranged in the exhaust gas aftertreatment system of the motor vehicle downstream of the catalytic converter region. The second oxygen sensor is arranged in the exhaust gas aftertreatment system of the motor vehicle at a position which, when the catalytic converter is installed as intended, is upstream of the catalytic converter. In other words, the second oxygen sensor is arranged in the exhaust gas aftertreatment system of the motor vehicle upstream of the catalytic converter region. The second oxygen sensor, arranged upstream of the catalytic converter region, triggers an integrator to integrate the oxygen flowing into the catalytic converter.Stopping of the integrator is triggered by the first oxygen sensor depending on the measured oxygen content in the exhaust gas. When used as intended, the catalytic converter is located in the catalytic converter area of ​​the motor vehicle's exhaust aftertreatment system. Based on the respective measured values ​​from the oxygen sensors, which particularly characterize the residual oxygen content of the exhaust gas in the exhaust system downstream of the catalytic converter area, the oxygen storage capacity of the catalytic converter expected to be installed in the exhaust system can be determined. The oxygen storage capacity describes the ability of the catalytic converter to temporarily store oxygen. The oxygen storage capacity decreases over the service life of the catalytic converter.If a very low actual oxygen storage capacity is determined for the catalyst area, one reason for this may be that the catalyst installed in the catalyst area is very aged or that no catalyst is installed in the catalyst area at all.

[0007] If the method determines that the actual oxygen storage capacity deviates from the target oxygen storage capacity by more than a predefined threshold, it is determined whether an error entry was created in the vehicle's error log within a defined time interval extending back in time. The error entry characterizes a fault in a vehicle component of the vehicle. If the actual oxygen storage capacity deviates from the target oxygen storage capacity by more than the predefined threshold, the cause may either be that the catalytic converter is very aged and therefore has a particularly low oxygen storage capacity, or the cause may be that no catalytic converter is installed in the catalytic converter area at all.In particular, the threshold value characterizes a value by which the actual oxygen storage capacity is below the target oxygen storage capacity.

[0008] The checked time interval can extend back into the past, starting from a point in time at which the actual oxygen storage capacity was determined or at which the actual oxygen storage capacity is compared with the target oxygen storage capacity. This check determines whether any error entries have been made in the vehicle's error log in the recent past. The method further provides that if it is determined that no error entry has been created in the error log during the time interval, it is determined that no catalytic converter is installed in the catalytic converter area.By checking for the presence of error entries in the error log, it can be analyzed whether the significant deviation between the determined actual oxygen storage capacity and the specified target oxygen storage capacity - where the deviation is above the specified threshold value - could have a cause other than the fact that no catalytic converter is installed in the vehicle. It could be the case that a catalytic converter is installed in the vehicle, but due to a fault in a vehicle component, the oxygen storage capacity of this installed catalytic converter is particularly low. To avoid incorrectly determining that no catalytic converter is installed in the vehicle in this case, the installation diagnosis takes into account whether or not error entries have been stored in the vehicle's error log during the time interval under consideration.The probability of incorrectly determining that no catalytic converter is installed in the vehicle, even though a catalytic converter is actually installed and the oxygen storage capacity of the catalytic converter is reduced merely due to a fault in a vehicle component, can be kept particularly low by this method. Thus, during installation diagnostics, it can be determined with particularly high reliability whether the catalytic converter is installed in the catalytic converter area of ​​the vehicle or whether no catalytic converter is installed in the catalytic converter area.

[0009] In a possible further development of the invention, it is provided that the actual oxygen storage capacity is determined several times in succession. This allows for continuous checking of whether the catalytic converter is installed in the catalytic converter area of ​​the motor vehicle. If the catalytic converter is removed from the catalytic converter area of ​​the motor vehicle at any time, this can be reliably determined using the installation diagnosis. In particular, the actual oxygen storage capacity can be checked several times at regular intervals. Furthermore, it is provided that the target oxygen storage capacity is a moving average of a defined number of the most recently determined values ​​for the actual oxygen storage capacity.Since the target oxygen storage capacity is the moving average of the multiple values ​​for the actual oxygen storage capacity, a sudden drop in the oxygen storage capacity for the catalytic converter area can be detected particularly reliably during the comparison using the specified threshold value. This sudden, sharp drop in oxygen storage capacity can be a strong indication that the catalytic converter has been removed from the catalytic converter area, provided that the significant reduction in the oxygen storage capacity of the catalytic converter area was not caused by a fault in a component of the vehicle.Because the target oxygen storage capacity was determined based on the respective values ​​determined for the actual oxygen storage capacity for the catalytic converter area of ​​this motor vehicle, the target oxygen storage capacity is not an abstract value, but rather a value specified individually for this catalytic converter area of ​​the motor vehicle. This allows a reliable determination of whether or not the catalytic converter is installed for this catalytic converter area.

[0010] In this context, it can be provided, in particular, that an exponentially weighted moving average is determined as the moving average. The exponentially smoothed mean assigns exponentially decreasing weights to the data points of a time series, whereby the weights characterize a share of the influence of the respective measured value for the actual oxygen storage capacity on the target oxygen storage capacity to be determined. Thus, more recent measured values ​​for the actual oxygen storage capacity are given a higher weighting than more ancient measured values. In other words, more recent determined values ​​for the actual oxygen storage capacity influence the determined target oxygen storage capacity more strongly than values ​​for the actual oxygen storage capacity determined further in the past.This involves an exponential weighting of the respective determined values ​​for the actual oxygen storage capacity, with the highest weightings being assigned to the most recently determined values ​​for the actual oxygen storage capacity. By comparing the determined value for the actual oxygen storage capacity to be analyzed with the specified target oxygen storage capacity, a sudden, significant reduction in the oxygen storage capacity of the catalyst area can be determined particularly reliably.Furthermore, due to the exponential weighting of the moving average of the respective values ​​for the actual oxygen storage capacity when determining the target oxygen storage capacity, it can be ensured that in the event of a continuous decrease in the oxygen storage capacity of the catalyst, this is recognized as such and is not incorrectly misinterpreted as a sudden, significant reduction in the oxygen storage capacity of the catalyst area.

[0011] In a further possible embodiment of the invention, if it is determined that no catalytic converter is installed in the catalytic converter area, an engine control lamp of the motor vehicle is activated and / or the available power of the motor vehicle is reduced. By activating the engine control lamp of the motor vehicle, a driver of the motor vehicle can be informed particularly reliably about the missing catalytic converter of the motor vehicle, which was determined during the installation diagnosis. Due to the illumination of the engine control lamp, the driver learns that a particularly urgent problem exists with the motor vehicle. As a result, the driver of the motor vehicle can address the problem of the missing catalytic converter in the catalytic converter area particularly quickly.Reducing the available power of the motor vehicle in response to the detection of the absence of a catalytic converter in the catalytic converter area makes it possible to keep pollutant emissions released into the environment by the motor vehicle's exhaust aftertreatment system particularly low. The lower the motor vehicle's power, the fewer pollutants are produced when the fuel is burned. If no catalytic converter is installed in the catalytic converter area, these pollutants enter the environment of the motor vehicle at least essentially unchanged. Because the available power of the motor vehicle is reduced, particularly few pollutants are released into the environment in the absence of a catalytic converter. This means that environmental pollution caused by the pollutants can be kept particularly low despite the missing catalytic converter.However, the primary goal of the power reduction is to impose a sanction on the driver for his previous actions that is clearly noticeable.

[0012] In a further possible embodiment of the invention, it is provided that it is determined that no catalyst is installed in the catalyst area if, for a defined number of successively carried out determination processes of the actual oxygen storage capacity, it has been determined that the respective determined actual oxygen storage capacity deviates from the target oxygen storage capacity by more than the predetermined threshold value and for each of these determination processes, it has been determined that no error entry has been created in the error memory in the respective assigned time interval.In other words, it is only determined that no catalytic converter is actually installed in the catalytic converter area if, in several consecutive determination processes, it has been determined that the respective determined actual oxygen storage capacity deviates from the target oxygen storage capacity by more than the specified threshold value, and additionally, no error entry has been made in the vehicle's error log, thus indicating a cause for a significant deviation between the respective determined actual oxygen storage capacities and the specified target oxygen storage capacity. This prevents the possibility of determining that no catalytic converter is installed in the catalytic converter area based on a single measurement of the actual oxygen storage capacity during installation diagnostics.Instead, the non-installation of a catalytic converter is only conclusively determined when, in the course of several consecutive measurements of the actual oxygen storage capacity, it has been determined that the determined values ​​for the actual oxygen storage capacity, combined with the absence of error entries in the error log, indicate that no catalytic converter is installed in the catalytic converter area. The determination that no catalytic converter is installed in the catalytic converter area is therefore only made when the probability of incorrectly determining that no catalytic converter is installed in the catalytic converter area is particularly low, despite the fact that a catalytic converter is actually installed in the catalytic converter area.At least one of the respective actions taken in response to the detected absence of a catalytic converter is thus only triggered if it has been ensured with high significance that there is actually no catalytic converter installed in the catalytic converter area. This ensures that the reduction in the available power of the vehicle is only triggered when it has been determined with particularly high reliability and thus with a particularly low probability of error that there is no catalytic converter installed in the catalytic converter area. The engine control light can illuminate as soon as it has been determined that the determined actual oxygen storage capacity is below the specified target oxygen storage capacity by more than the specified threshold value.

[0013] In a further possible embodiment of the invention, the fault memory is also checked for the presence of an error entry characterizing a combustion process in an internal combustion engine of the motor vehicle. In particular, faulty combustion in the internal combustion engine can significantly impair the residual oxygen content in the exhaust gas, which in turn influences the actual oxygen storage capacity of the catalytic converter determined based on the residual oxygen content in the exhaust gas. This means that the fault in the motor vehicle component does not necessarily affect the actual oxygen storage capacity of the catalytic converter; instead, possibly, only the measured value for the residual oxygen content, which is used to determine the oxygen storage capacity of the catalytic converter.If, as part of the installation diagnosis, it is taken into account whether there are any error entries in the error log, in particular error entries that characterize the combustion process in the internal combustion engine, then a particularly low actual oxygen storage capacity can be attributed to the error in the combustion process and the erroneous determination of a missing catalyst in the catalyst area can be avoided. For example, the error entry in the error log may characterize that a spark plug in the vehicle's internal combustion engine is not functioning. As a result of the malfunctioning spark plug, incomplete combustion of the fuel injected into the internal combustion engine can result. This incomplete combustion of the fuel in the internal combustion engine can, in turn, result in a different residual oxygen content in the exhaust gas than would result from complete combustion of this fuel.By including the error entry in the error memory, it can be avoided that it is incorrectly determined that no catalyst is installed in the catalyst area due to the residual oxygen content in the exhaust gas that is subsequently determined, which is used to determine the actual oxygen storage capacity of the catalyst.

[0014] The invention further relates to an electronic computing device for a motor vehicle, in particular a motorcycle or a motor vehicle, in particular a passenger car, (which is configured to carry out a method as already described in connection with the method according to the invention for carrying out the installation diagnosis. The electronic computing device can be configured to determine the actual oxygen storage capacity for the catalyst area and to compare it with the desired oxygen storage capacity for the catalyst area.Furthermore, the electronic computing device can be configured to determine whether the error entry was created in the motor vehicle's error memory within the defined time interval extending into the past if the electronic computing device has determined that the actual oxygen storage capacity deviates from the target oxygen storage capacity by more than the predetermined threshold value. Furthermore, the electronic computing device can be configured to determine that no catalytic converter is installed in the catalytic converter area if the electronic computing device determines that no error entry was created in the error memory within the time interval.Furthermore, the electronic computing device can be configured to trigger, as a result of determining that no catalytic converter is installed in the catalytic converter area, an action such that an engine control lamp of the motor vehicle is activated and / or an available power of the motor vehicle is reduced.

[0015] The invention further relates to a motor vehicle with an electronic computing device as has already been described in connection with the electronic computing device according to the invention.

[0016] Further features of the invention may emerge from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0017] The drawing shows: Fig. 1 is a schematic sectional view of a portion of an exhaust aftertreatment system of a motor vehicle; and Fig. 2 a process diagram for a method for carrying out an installation diagnosis of a catalytic converter of a motor vehicle.

[0018] In Fig. 1 shows a section of an exhaust gas aftertreatment system 10 of a motor vehicle in a sectional view. The motor vehicle can be a motor vehicle or a motorcycle, such as a motorcycle in particular. The exhaust gas aftertreatment system 10 comprises a catalytic converter region 12, in which a catalytic converter 14 is usually installed. Exhaust gas 18 flows through the exhaust gas aftertreatment system 10 in a flow direction 16. The exhaust gas 18 is produced when a fuel-air mixture is burned in an internal combustion engine of the motor vehicle. The catalytic converter 14 is provided for aftertreating the exhaust gas 18 produced during the combustion process, wherein pollutants present in the exhaust gas 18 are chemically converted into harmless components. Downstream of the catalytic converter 14 in the exhaust gas aftertreatment system 10, a first oxygen sensor 20 is arranged, and upstream of the catalytic converter 14 in the exhaust gas aftertreatment system 10, a second oxygen sensor 22 is arranged.The oxygen sensors 20 are so-called lambda sensors, which are designed to determine the oxygen content in a gas, in this case the exhaust gas 18, downstream of the catalytic converter 14. Based on the residual oxygen content of the exhaust gas 18 downstream of the catalytic converter 14, the condition of the catalytic converter 14 can be determined via its oxygen storage capacity. The oxygen storage capacity is therefore a substitute value from which the condition of the catalytic converter 14 can be determined. The oxygen storage capacity is the ability of the catalytic converter 14 to store oxygen. High temperatures in the catalytic converter 14 lead to aging of the catalytic converter 14. As a result, the conversion capacity of the catalytic converter 14 changes. The oxygen storage capacity of the catalytic converter 14 decreases over its operating life. The oxygen storage capacity of the catalytic converter 14 can be measured at specific operating points.For certain operating values ​​of the motor vehicle's internal combustion engine, the residual oxygen content of the exhaust gas 18 exiting the internal combustion engine upstream of the catalytic converter 14 is known because the ratio of the stoichiometric mixture is known. To determine the oxygen storage capacity of the catalytic converter 14, an undersupply of oxygen in the exhaust gas 18 upstream of the catalytic converter 14 can first be adjusted via the stoichiometric mixture of fuel and air in the internal combustion engine. As a result, oxygen stored in the catalytic converter 14 is consumed. Subsequently, an excess of oxygen in the exhaust gas 18 is created by adjusting the stoichiometric ratio of the fuel and air mixture in the internal combustion engine. The second oxygen sensor 22 upstream of the catalytic converter 14 measures when the excess oxygen reaches the catalytic converter 14.The first oxygen sensor 20 measures downstream of the catalytic converter 14 whether or when oxygen is present in the exhaust gas 18 downstream of the catalytic converter 14, thus determining whether or when the catalytic converter 14 is fully loaded with oxygen. If oxygen is measured downstream of the catalytic converter 14, it can be assumed that the catalytic converter 14 is fully loaded with oxygen and can no longer store any more oxygen. To determine the oxygen storage capacity of the catalytic converter 14, a measurement is taken of how much oxygen is stored in the catalytic converter 14 after the catalytic converter 14 has been emptied of oxygen and starting from the beginning of an excess supply of oxygen in the exhaust gas 18.

[0019] To determine whether a catalyst 14 is actually installed in the catalyst area 12 or whether the catalyst 14 has been removed from the catalyst area 12, an installation diagnosis is provided. A process diagram for a method for performing an installation diagnosis of the catalyst 14 is shown in Fig.2. The method comprises a first method step V1, a second method step V2, and a third method step V3, wherein the method steps V1 to V3 follow one another consecutively. In the first method step V1, the actual oxygen storage capacity for the catalyst region 12 is determined based on the residual oxygen content in the exhaust gas 18 determined by the first oxygen sensor 20 downstream of the catalyst region 12 and the residual oxygen content in the exhaust gas 18 determined by the second oxygen sensor 22 upstream of the catalyst region 12. This determined actual oxygen storage capacity is compared with a predetermined target oxygen storage capacity for this catalyst region 12. This predetermined target oxygen storage capacity can be a moving average of a defined number of recently determined values ​​for the actual oxygen storage capacity.In particular, the determined target oxygen storage capacity may be an exponentially weighted moving average of the most recently determined values ​​for the actual oxygen storage capacity.

[0020] If it is determined during the first method step V1 that the actual oxygen storage capacity deviates from the target oxygen storage capacity by more than a predetermined threshold value, then the second method step V2 determines whether an error entry characterizing a fault in a motor vehicle component of the motor vehicle has been created in the motor vehicle's error log within a defined time interval extending into the past. In this case, the error log is checked, in particular, for the presence of an error entry characterizing a combustion process in the motor vehicle's internal combustion engine.It is thus determined whether, in addition to the fact that the determined actual oxygen storage capacity for the catalyst region 12 deviates from the predetermined target oxygen storage capacity by more than the predetermined threshold value, at least one error entry has been entered in the error memory of the motor vehicle in the recent past or whether no error entry has been created in the error memory in the time interval under consideration.

[0021] If it is determined in the second method step V2 that no error entry has been created in the error memory in the time interval, then it is determined in the third method step V3 that no catalyst 14 is installed in the catalyst area 12.In order to keep the risk of incorrectly determining that the catalytic converter 14 is not installed as low as possible, it can be provided that, within the scope of the third method step V3, it is only determined that no catalytic converter 14 is installed in the catalytic converter region 12 when, for a defined number of consecutively performed determination processes for the actual oxygen storage capacity, it has been determined that the respective determined actual oxygen storage capacity deviates from the target oxygen storage capacity by more than a predetermined threshold value and, for each of these determination processes, it has been determined that no error entry was created in the error memory in the respective assigned time interval. A determination process consists of the first method step V1 and the consecutively performed second method step V2.

[0022] If it is determined for several determination processes carried out in immediate succession that both the respective determined actual oxygen storage capacity deviates from the assigned predetermined target oxygen storage capacity by more than the specified threshold value and, in addition, there is no error entry in the error system for the assigned time interval, then it is only determined in the third method step V3 that no catalyst 14 is installed in the catalyst area 12. Thus, the determination that no catalyst 14 is installed in the catalyst area 12 is only made when, based on the several determination processes carried out in immediate succession, it can be assumed with particular certainty that, in fact, no catalyst 14 is installed in the catalyst area 12.As a result, the probability of error that it is incorrectly determined that no catalyst 14 is installed in the catalyst area 12, although the catalyst 14 is actually installed in the catalyst area 12, can be kept particularly low.

[0023] If it has been determined in the third method step V3 that no catalyst 14 is installed in the catalyst area 12, then the action triggered is that an engine control lamp of the motor vehicle is activated and, if necessary, an available power of the motor vehicle is also reduced.

[0024] If it is determined in the second method step V2 that at least one error entry has been created in the error memory in the time interval, wherein the error entry relates to a motor vehicle component which has an influence on the determination of the oxygen storage capacity, then the determination that no catalytic converter 14 is installed in the catalytic converter region 12 is omitted.

[0025] Known systems for analyzing an exhaust aftertreatment system 10 of a motor vehicle are designed solely to detect deterioration in the catalytic properties of the catalyst 14. These diagnoses are not robust enough for installation testing or impair this diagnostic purpose.

[0026] An efficiency diagnosis can be implemented by determining the oxygen storage capacity of the catalytic converter 14. On the one hand, it is in the manufacturer's interest to have the greatest possible security against error detections of a faulty system in the field in order to avoid the catalytic converter 14 being replaced even though it is still in working order. On the other hand, the detection of catalytic converters 14 that no longer meet legal requirements is absolutely necessary. This method, which can only be implemented robustly with considerable effort and is based solely on the oxygen storage capacity of the catalytic converter 14, can only provide further information regarding whether or not the catalytic converter 14 is installed with significant limitations.This is primarily due to the fact that the oxygen storage capacity of the catalytic converter 14, which just meets the legal requirements and therefore does not yet need to be replaced, may not differ so significantly from the oxygen storage capacity resulting from a pure gas transit time of the exhaust gas 18 through the exhaust gas aftertreatment line 10 when no catalytic converter 14 is installed in the catalytic converter area 12, that a sufficiently robust diagnostic result can be obtained based on the oxygen storage capacity alone.

[0027] Within the scope of the described method for performing the installation diagnosis, a sudden decrease in absolute diagnostic values ​​for the oxygen storage capacity determined over a long period of time, combined with the moving average as the target oxygen storage capacity and a freely definable number of consecutive entries in the error log, leads to a robust assessment of whether the catalytic converter 14 has been removed from the catalytic converter area 12. If, for example, it is determined for at least three determination processes carried out immediately one after the other that the actual oxygen storage capacity deviates from the respectively assigned predetermined target oxygen storage capacity by more than the predetermined threshold value and no entry was made in the error log of the motor vehicle in any of the time intervals considered, then it is determined that no catalytic converter 14 is installed in the catalytic converter area 12.As a result, the action of the motor vehicle is triggered, in particular the engine control light is activated and / or the available power of the motor vehicle is restricted.

[0028] The exponentially weighted moving average is also known as the exponentially weighted moving average. To determine the target oxygen storage capacity, the average is taken from a specified number of recent measured values ​​of the actual oxygen storage capacity immediately before the value used for comparison. The analysis within the scope of the installation diagnosis is carried out in combination with error entries in the vehicle's error log. If, for example, the spark plug in a cylinder of the combustion engine is defective, the fuel only burns in the catalytic converter 14, which can damage the catalytic converter 14. As a result, the oxygen storage capacity of the catalytic converter 14 can be reduced despite the fact that it is installed in the catalytic converter area 12.If the motor vehicle is in a fault-free condition, which is characterized by the absence of any fault entry in the motor vehicle's fault memory, and a sudden change in the determined oxygen storage capacity for the catalytic converter 14 occurs without any other influences, then tampering is suspected and thus the suspicion that the catalytic converter 14 has been removed from the exhaust aftertreatment system 10. To be certain, a predetermined number of further diagnostic events are waited for before it is finally determined that no catalytic converter 14 is installed in the catalytic converter area 12.

[0029] Overall, the invention shows how a catalyst installation diagnosis can be carried out. List of reference symbols 10 Exhaust aftertreatment system 12 Catalyst area 14 Catalyst 16 Flow direction 18 Exhaust 20 Oxygen sensor 22 Oxygen sensor V1 to V3 respective process steps QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2008 038 677 B4

[0002]

Claims

[1] Method for carrying out an installation diagnosis of a catalytic converter (14) of a motor vehicle, in which - by means of two oxygen sensors (20, 22) an actual oxygen storage capacity is determined for a catalyst region (12) of an exhaust gas aftertreatment system (10) of the motor vehicle in which the catalyst (14) is installed when used as intended, and is compared with a target oxygen storage capacity for the catalyst region (12) (V1), - if it is determined that the actual oxygen storage capacity deviates from the target oxygen storage capacity by more than a specified threshold value: determining whether an error entry characterising a fault in a motor vehicle component of the motor vehicle has been created in an error memory of the motor vehicle within a defined time interval extending into the past (V2), - if it is determined that no error entry has been created in the error memory during the time interval: Determine that no catalyst (14) is installed in the catalyst area (12) (V3). [2] Method according to claim 1, characterized by that the actual oxygen storage capacity is determined several times in succession and the target oxygen storage capacity is a moving average of a defined number of last determined values for the actual oxygen storage capacity. [3] Method according to claim 2, characterized by that an exponentially weighted moving average is determined as the moving average. [4] Method according to one of the preceding claims, characterized by that if it is determined that no catalyst (14) is installed in the catalyst area (12), then an engine control lamp of the motor vehicle is activated and / or an available power of the motor vehicle is reduced. [5] Method according to one of the preceding claims, characterized by that it is determined that no catalyst (14) is installed in the catalyst area (12) if, for a defined number of successive determination processes of the actual oxygen storage capacity, it has been determined that the respective determined actual oxygen storage capacity deviates from the target oxygen storage capacity by more than the predetermined threshold value and for each of these determination processes, it has been determined that no error entry has been created in the error memory in the respective assigned time interval. [6] Method according to one of the preceding claims, characterized by that the error memory is checked for the presence of an error entry characterising a combustion process in an internal combustion engine of the motor vehicle (V2). [7] Electronic computing device for a motor vehicle, which is designed to carry out a method according to one of the preceding claims. [8] Motor vehicle, comprising an electronic computing device according to the preceding claim.

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