DE102024107801B3 - Method for operating a drive device for a motor vehicle, corresponding drive device and computer program product - Google Patents

Abstract

The invention relates to a method for operating a drive device (1) for a motor vehicle, which drive unit (2) has an exhaust gas-generating drive unit (2) and an exhaust gas aftertreatment device (12) designed as a vehicle catalytic converter for aftertreating the exhaust gas, wherein an output content of the at least one exhaust gas component present downstream of the exhaust gas aftertreatment device (12) is determined at least temporarily by means of a catalytic converter model from an input content of at least one exhaust gas component of the exhaust gas present upstream of the exhaust gas aftertreatment device (12) using a temperature of the exhaust gas aftertreatment device (12). It is provided that a temporal profile of a combustion air ratio in the exhaust gas is additionally taken into account when determining the output content. The invention further relates to a drive device (1) for a motor vehicle and to a computer program product.

Description

The invention relates to a method for operating a drive device for a motor vehicle, which has a drive unit generating exhaust gas and an exhaust gas aftertreatment device designed as a vehicle catalytic converter for aftertreating the exhaust gas, wherein by means of a catalytic converter model, an output content of the at least one exhaust gas component present downstream of the exhaust gas aftertreatment device is determined at least temporarily from an input content of at least one exhaust gas component of the exhaust gas present upstream of the exhaust gas aftertreatment device using a temperature of the exhaust gas aftertreatment device, wherein a temporal profile of a combustion air ratio in the exhaust gas is additionally taken into account when determining the output content. The invention further relates to a drive device for a motor vehicle and a computer program product.

The state of the art includes, for example, the publication DE 10 2013 010 562 A1 This describes a method for determining the HC conversion capability of a catalyst arranged in an exhaust gas flow path of an internal combustion engine and designed to convert hydrocarbons by means of an oxygen-sensitive sensor arranged downstream of the catalyst in the exhaust gas flow path, which sensor has cross-sensitivity to hydrocarbons. The method comprises the steps of: detecting a first signal from the downstream sensor in a first situation in which a first HC fraction is present in the exhaust gas upstream of the catalyst, detecting a second signal from the downstream sensor in a second situation in which a second HC fraction is present in the exhaust gas upstream of the catalyst, which second HC fraction is higher than the first HC fraction, and determining the HC conversion capability of the catalyst as a function of the first and second signals from the downstream sensor.

The printed matter DE 100 08 563 A1 relates to a diagnosis of a NO _X storage catalytic converter which is arranged in the exhaust system of an internal combustion engine and can be operated in an absorption mode and a regeneration mode depending on the lambda value, the NO _X concentration in the exhaust gas being measured downstream of the NO _X storage catalytic converter. It is provided that when the NO _X storage catalytic converter transitions from the absorption mode to the regeneration mode, the values of characteristic features of a NO _X desorption peak are determined over time in the NO _X concentration profile, compared with predetermined test patterns, a comparison result is formed and a catalytic converter status signal, in particular an error signal, formed depending on the comparison result is stored and/or displayed.

The printed publications DE 101 60 704 A1 , DE 603 17 219 T2 and JP 2000 - 154 713 A known.

It is an object of the invention to propose a method for operating a drive device for a motor vehicle, which has advantages over known methods, in particular achieving a higher accuracy in determining the initial content.

This is achieved according to the invention with a method for operating a drive device for a motor vehicle having the features of claim 1. It is provided that an influencing factor of a catalyst poison on the exhaust gas aftertreatment device is calculated from the time course and taken into account when determining the initial content.

Advantageous embodiments with useful further developments of the invention are specified in the dependent claims. It should be noted that the exemplary embodiments explained in the description are not limiting; rather, any variations of the features disclosed in the description, the claims, and the figures are feasible.

The method is provided for operating the drive device. The drive device serves to drive the motor vehicle, thus providing a drive torque directed towards driving the motor vehicle. The drive unit provides the drive torque. The drive unit is preferably in the form of an internal combustion engine, in particular a gasoline internal combustion engine or a diesel internal combustion engine. During operation of the drive device, fuel and fresh gas are supplied to the drive unit at least temporarily, wherein the fresh gas at least temporarily contains fresh air. In addition, the fresh gas can comprise exhaust gas, provided that exhaust gas recirculation is implemented, in which the exhaust gas generated by the drive unit is at least partially recirculated into the drive unit, namely as a component of the fresh gas. The fuel and the fresh gas supplied to the drive unit form a fuel-fresh gas mixture with a specific composition, which is reacted in the drive unit.

During operation of the drive unit, exhaust gas is produced due to the chemical reaction between fuel and fresh gas, which is discharged towards the outside environment of the drive device or the motor vehicle. Since the exhaust gas produced by the drive unit contains pollutants, the exhaust gas is first fed to the exhaust gas aftertreatment device before being released into the outside environment. In the exhaust gas aftertreatment device, the pollutants are at least partially converted into less hazardous products. Only after passing through the exhaust gas aftertreatment device is the exhaust gas discharged into the outside environment, in particular through a tailpipe of the drive device.

The exhaust gas aftertreatment device is in the form of a vehicle catalyst, in particular a three-way catalyst, oxidation catalyst, _NOx storage catalyst, or SCR catalyst, or at least comprises one. Particularly preferably, the vehicle catalyst is integrated into a particulate filter, in particular a gasoline particulate filter or a diesel particulate filter. For this purpose, the particulate filter is provided with a catalytic coating, for example. The conversion rate and thus the conversion performance of the exhaust gas aftertreatment device, with which the pollutants are converted into less hazardous products, depend in particular on the composition of the exhaust gas supplied to the exhaust gas aftertreatment device and the temperature of the exhaust gas aftertreatment device.

In addition, the conversion rate or the conversion performance can depend on a storage load of the exhaust gas aftertreatment device, which in turn is related to the composition of the exhaust gas. The storage load is to be understood as a loading of the exhaust gas aftertreatment device with an exhaust gas component of the exhaust gas, i.e. the amount of exhaust gas component temporarily stored in the exhaust gas aftertreatment device. This exhaust gas component is preferably different from the at least one exhaust gas component, for example it is present in the form of oxygen. Additionally or alternatively, a state of the exhaust gas aftertreatment device usually influences the conversion rate and thus the conversion performance. The state is to be understood in particular as an aging state that steadily worsens over the service life of the exhaust gas aftertreatment device and is preferably described by an aging variable assigned to the exhaust gas aftertreatment device.

The condition of the exhaust gas aftertreatment system can be determined, for example, by first determining the storage capacity, in particular the oxygen storage capacity, of the exhaust gas aftertreatment system. From this, the condition is preferably derived or the aging variable is determined. A defect in the exhaust gas aftertreatment system is preferably detected as soon as the storage capacity falls below a capacity threshold. Accordingly, it can be provided to operate the drive system depending on the storage capacity and/or the aging variable.

The components of the exhaust gas produced by the drive unit are also referred to as raw emissions. Raw emissions describe the composition of the exhaust gas upstream of the exhaust gas aftertreatment device, or in terms of flow between the drive unit and the exhaust gas aftertreatment device. The substances contained in the exhaust gas are partially converted as the exhaust gas passes through the exhaust gas aftertreatment device, changing the composition of the exhaust gas. The substances present in the exhaust gas downstream of the exhaust gas aftertreatment device, which make up the exhaust gas, are also referred to as tailpipe emissions, since the exhaust gas with this composition is released into the outside environment through the tailpipe of the drive unit.

The amount of pollutants contained in the tailpipe emissions depends, as already mentioned, on the raw emissions, but also on the conversion efficiency of the exhaust aftertreatment system. This depends, among other things, on temperature. In particular, the further the temperature of the exhaust aftertreatment system is from the operating temperature of the exhaust aftertreatment system, i.e., the greater the absolute value of the difference between the temperatures, the lower the conversion efficiency. The temperature of the exhaust aftertreatment system refers, in particular, to the temperature of a ceramic honeycomb body provided with the catalytic coating.

Due to the ever-increasingly strict regulations for exhaust emissions, these must be monitored more closely. Since the content of all exhaust gas components cannot be measured, or a sensor cannot be available for each exhaust gas component, the catalyst model is used to calculate the output content for at least one exhaust gas component from the input content, in particular using the conversion performance. The catalyst model uses at least the temperature of the exhaust aftertreatment system.

Wherever this description refers to the exhaust gas component or the at least one exhaust gas component, the statements are always equivalent. All statements directed at the exhaust gas component are therefore transferable to the at least one exhaust gas component and vice versa. The input content and the output content are content values or content variables and each indicate the content of the exhaust gas component in the exhaust gas. The content values are given, for example, as mass fractions, molar fractions, or volume fractions. However, they can also be given as mass concentrations, molar concentrations, or volume concentrations.

Investigations by the applicant have surprisingly shown that a significant improvement in the catalyst model can be achieved if, in addition to the temperature, the temporal progression of the combustion air ratio in the exhaust gas is also taken into account. If the power unit was previously operated with a rich fuel/fresh gas mixture, the catalyst model should provide a different value for the output concentration at the same input concentration than if the power unit were operated with a lean fuel/fresh gas mixture.

When the drive unit is operated with a rich fuel/fresh gas mixture, i.e. when there is a lack of oxygen, carbon monoxide is introduced into the exhaust gas aftertreatment device, which reversibly accumulates there, resulting in carbon monoxide poisoning of the exhaust gas aftertreatment device. This applies in particular to a precious metal used in the exhaust gas aftertreatment device, in particular platinum and/or palladium. When carbon monoxide is enriched in the exhaust gas aftertreatment device, the conversion performance of the exhaust gas aftertreatment device for carbon monoxide and/or hydrocarbons drops significantly, especially when the drive unit is operated with the rich fuel/fresh gas mixture. By taking this effect into account in the catalyst model, the initial content of the at least one exhaust gas component can be determined with high accuracy.

Preferably, the initial content determined using the catalyst model is monitored and, if the initial content exceeds a threshold value, a malfunction of the drive system is detected. Alternatively, it can be provided to determine and accumulate a quantity of the exhaust gas component downstream of the exhaust gas aftertreatment device based on the initial content. For example, if a limit value is exceeded, the cumulative quantity of the exhaust gas component based on a distance traveled by the motor vehicle is detected as a malfunction of the drive system. The quantity is understood to mean, in particular, a mass or volume of the exhaust gas component.

If the malfunction is detected, faulty operation of the drive system is preferably initiated, in particular the drive system is operated in such a way that, despite the malfunction, the initial concentration is lower than the threshold value or the cumulative amount based on the distance traveled by the motor vehicle is within a permissible range. Generally speaking, the drive system is operated depending on the initial concentration, or the drive unit is controlled depending on the initial concentration. This ensures reliable compliance with the limit values for the motor vehicle's exhaust emissions.

A further development of the invention provides that several values of the combustion air ratio are measured at intervals using a lambda probe and stored in the curve. The lambda probe is preferably arranged upstream of the exhaust gas aftertreatment device, so that it determines the combustion air ratio in the exhaust gas upstream of the exhaust gas aftertreatment device. Several values of the combustion air ratio are measured, namely at intervals, in particular at regular intervals. The values are entered into the curve.

The lambda probe preferably measures a residual oxygen content in the exhaust gas and uses this to determine the combustion air ratio. The combustion air ratio determined by the lambda probe can serve as the basis for adjusting the composition of the fuel/fresh gas mixture. In particular, the composition is adjusted such that the combustion air ratio changes toward a target value, in particular up to the target value. For example, the combustion ratio is regulated by adjusting the composition of the fuel/fresh gas mixture to the target value.

Preferably, there are several lambda probes, namely upstream of the exhaust gas aftertreatment device a first lambda probe for measuring a first combustion air ratio in the exhaust gas and a second lambda probe for Measuring a second air/fuel ratio in the exhaust gas. Preferably, multiple lambda probes are present; in particular, the first lambda probe is arranged upstream of the exhaust gas aftertreatment device, and the second lambda probe is arranged downstream of the exhaust gas aftertreatment device. The first lambda probe is used, in particular, as the aforementioned lambda probe.

The first lambda sensor is used to determine the first combustion air ratio, and the second lambda sensor is used to determine the second combustion air ratio. The first combustion ratio corresponds to a combustion air ratio in the exhaust gas upstream of the exhaust gas aftertreatment device, i.e., in terms of flow, between the drive unit and the exhaust gas aftertreatment device. The second combustion ratio is a combustion air ratio present in the exhaust gas downstream of the exhaust gas aftertreatment device.

The two combustion air ratios, i.e., the first combustion ratio and the second combustion air ratio, are preferably used to operate the drive system. For example, they are used to implement lambda control. In particular, the composition of the fuel/fresh gas mixture is adjusted based on the first combustion air ratio, whereas the second combustion air ratio is used to correct the first association air ratio as part of a trim control. Ultimately, lambda control is therefore based on both the first combustion air ratio and the second combustion air ratio.

Preferably, the first lambda sensor is a broadband lambda sensor, and the second lambda sensor is a step-type lambda sensor. The broadband lambda sensor enables the residual oxygen content or the corresponding combustion air ratio to be measured over a wider measuring range than the step-type lambda sensor. The broadband lambda sensor is preferably used to implement the aforementioned lambda control and, accordingly, to adjust the composition of the fuel/fresh gas mixture with which the drive unit is operated.

The step-off lambda sensor has a narrower measuring range than the broadband lambda sensor; in particular, it is used (only) to detect a combustion air ratio of λ = 1. However, the measurement accuracy of the step-off lambda sensor is higher than that of the broadband lambda sensor. Deviations and errors of the broadband lambda sensor are preferably at least partially compensated using the trim control or by using the step-off lambda sensor. This allows the composition of the fuel-fresh gas mixture to be adjusted with high precision.

A further development of the invention provides that the curve comprises values for the combustion air ratio over a period of at least 1 s, at least 2 s or at least 5 s. In this respect, the curve comprises historical values for the combustion air ratio which, starting from the current point in time, extend over the stated period into the past. The period comprises at least 1 s, at least 2 s or at least 5 s. It can also be provided that the period comprises longer periods, for example at least 10 s, at least 15 s or at least 20 s. However, the period is preferably limited in terms of its length, in particular it comprises a maximum of 30 s, a maximum of 25 s or a maximum of 20 s. A period for the curve of at least 2 s and a maximum of 10 s or a maximum of 5 s is particularly preferred.

Longer periods are usually not necessary, since values for the combustion air ratio from further back in time have little or no influence on the conversion rate of the exhaust gas aftertreatment system. The curve is preferably implemented using a FIFO memory (FIFO: First In First Out). This means that the curve contains only a certain number of values for the combustion air ratio, and when the current value of the combustion air ratio is stored, the oldest value is removed from the curve. This enables an efficient procedure for determining the initial content of at least one exhaust gas component.

A further development of the invention provides that the profile of the combustion air ratio is taken into account as a function of the temperature of the exhaust gas aftertreatment device. In this respect, the temperature is not only used directly to determine the conversion efficiency, but also indirectly influences it or the initial content by taking into account the temporal profile. In this respect, the temperature of the exhaust gas aftertreatment device is used several times when determining the initial content. The reason for this is that the described effect, namely that the initial content depends on the temporal profile of the combustion air ratio for an identical input content, decreases with increasing temperature of the exhaust gas aftertreatment device.

For example, it may be provided that the combustion air ratio profile is only taken into account when determining the initial content if the temperature of the exhaust gas aftertreatment device is lower than a threshold value. However, if the temperature is equal to or higher than the threshold value, the initial content is determined independently of the temporal profile. In more general terms, the higher the temperature, the less the profile is taken into account when determining the initial content. This achieves a particularly high degree of accuracy in determining the initial content.

A further development of the invention provides that the profile of the combustion air ratio is taken into account as a function of a state of the exhaust gas aftertreatment device. The state is, in particular, an age-related state of the exhaust gas aftertreatment device. The state of the exhaust gas aftertreatment device is described, for example, by the aforementioned aging variable. The aging variable describes the aging of the exhaust gas aftertreatment device, i.e., age-related influences on it. For example, the aging variable describes the storage capacity of the exhaust gas aftertreatment device for the exhaust gas component, an exhaust gas component different from this, or is determined from it.

The conversion efficiency of the exhaust gas aftertreatment system depends significantly on the condition of the exhaust gas aftertreatment system and thus on the aging parameter, as the conversion efficiency decreases with increasing age due to various influences. Furthermore, the effect that the output concentration, with an identical input concentration, depends on the temporal progression of the combustion air ratio becomes more pronounced with increasing age. Therefore, the older the exhaust gas aftertreatment system, the more advantageous it is to consider the temporal progression. Consequently, by considering the aging parameter, the accuracy of the catalyst model can be significantly improved.

The invention provides that an influencing factor of a catalyst poison on the exhaust gas aftertreatment device is calculated from the time profile and taken into account when determining the initial content. The catalyst poison is, for example, the at least one exhaust gas component, but an exhaust gas component different from this can also be used as the catalyst poison. The catalyst poison is understood to be an exhaust gas component which has an adverse effect on the conversion rate or the conversion performance of the exhaust gas aftertreatment device and which accumulates in particular in the exhaust gas aftertreatment device. The influencing factor describes the influence of the catalyst poison on the conversion rate or the conversion performance and thus on the initial content of the at least one exhaust gas component.

The influencing factor is determined from the temporal progression, for example by balancing the catalyst poison based on the temporal progression, in particular balancing the amount of catalyst poison present in the exhaust gas aftertreatment system. During the balancing process, both the entry and exit of the catalyst poison into the exhaust gas aftertreatment system are considered. Entry occurs, for example, when the drive unit is operating with a rich fuel/fresh gas mixture, whereas exit occurs when it is operating with a lean fuel/fresh gas mixture. The influencing factor calculated from the temporal progression is taken into account when determining the initial content, so that the temporal progression is indirectly included via the influencing factor. The advantages already explained are achieved using the procedure described.

A further development of the invention provides that the at least one exhaust gas component or an exhaust gas component different from the at least one exhaust gas component is used as the catalyst poison. Such a procedure has already been mentioned.

A further development of the invention provides that the output content is determined from the input content using a conversion power for the at least one exhaust gas component, wherein the conversion power is lower the greater the proportion of a combustion air ratio corresponding to oxygen deficiency in the temporal profile. The output content of the at least one output component is thus a function of the input content and the conversion power. The conversion power is determined at least based on the temperature of the exhaust gas aftertreatment device and based on the temporal profile of the combustion air ratio. For example, the conversion power is a factor with which the input content is applied to determine the output content.

It is particularly preferred that the conversion power is read out from a characteristic map using the temperature and the time profile of the combustion air ratio. In addition, when reading out The characteristic map takes into account the condition of the exhaust aftertreatment system. Using the characteristic map allows for particularly simple determination of the initial concentration and requires only minimal computing power.

The invention further relates to a drive device for a motor vehicle, in particular for carrying out the method according to the embodiments within the scope of this description, wherein the drive device has a drive unit generating exhaust gas and an exhaust gas aftertreatment device designed as a vehicle catalyst for aftertreating the exhaust gas and is provided and designed to use a catalyst model to at least temporarily determine an output content of the at least one exhaust gas component present downstream of the exhaust gas aftertreatment device from an input content of at least one exhaust gas component of the exhaust gas present upstream of the exhaust gas aftertreatment device, using a temperature of the exhaust gas aftertreatment device. The drive device is further provided and designed to additionally take into account a temporal profile of a combustion air ratio in the exhaust gas when determining the output content. The drive device is further provided and designed to calculate an influencing factor of a catalyst poison on the exhaust gas aftertreatment device from the temporal profile and to take this into account when determining the output content.

The advantages of such a design of the drive direction or such a procedure have already been pointed out. Both the drive device for a motor vehicle and the method for its operation can be further developed according to the explanations in this description, so reference is made to these in this regard.

The invention also relates to a computer program product comprising instructions that cause the drive device to execute the described method according to the embodiments of this description. Regarding the advantages and possible advantageous developments, reference is made to the entire description.

The features and feature combinations described in the description, in particular the features and feature combinations described in the following description of the figures and/or shown in the figures, can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments are also to be considered encompassed by the invention that are not explicitly shown or explained in the description and/or the figures, but which emerge from or can be derived from the explained embodiments.

• 1 eine schematische Darstellung einer Antriebseinrichtung für ein Kraftfahrzeug, sowie
• 2 mehrere Diagramme, in welchen eine Konvertierungsleistung einer Abgasnachbehandlungseinrichtung der Antriebseinrichtung in unterschiedlichen Situationen über einem Verbrennungsluftverhältnis aufgetragen ist.

The invention will be explained in more detail below with reference to the exemplary embodiments shown in the drawings, without limiting the invention. In the drawings:

• 1 a schematic representation of a drive device for a motor vehicle, as well as
• 2 several diagrams in which a conversion performance of an exhaust gas aftertreatment device of the drive device is plotted against a combustion air ratio in different situations.

The 1 shows a schematic representation of a drive device 1, which has a drive unit 2, which here is in the form of an internal combustion engine, and an exhaust tract 3. In the illustrated embodiment, the drive unit 2 has a plurality of cylinders 4, each with a combustion chamber. Each of the cylinders 4 has at least one intake valve 5 and at least one exhaust valve 6. Fresh gas from a fresh gas tract 7 can be supplied to the respective cylinder 4 via each of the intake valves 5, whereas exhaust gas from the corresponding cylinder 4 can be discharged through each of the exhaust valves 6, namely in the direction of the exhaust tract 3.

The fresh gas is provided to the intake valves 5 by means of a compressor 8, which is part of an exhaust gas turbocharger 9. In addition to the compressor 8, the exhaust gas turbocharger 9 has a turbine 10, which is fluidly connected to the exhaust valves 6 via an exhaust line 11, which is part of the exhaust tract 3. Downstream of the turbine 10 is an exhaust gas aftertreatment device 12, which is designed here as a vehicle catalytic converter. Downstream of the exhaust gas aftertreatment device 12, the exhaust tract 3 opens into an external environment of the drive device 1, for example via a tailpipe. It should be noted that the exhaust gas turbocharger 9 is purely optional. It can also be omitted accordingly.

Upstream of the exhaust gas aftertreatment device 12 is a first lambda probe 13 for determining a first residual oxygen content and, accordingly, a first combustion air ratio of the exhaust gas. Downstream of the exhaust gas aftertreatment device 12, a second lambda probe 14 is used to determine a second residual oxygen content and, accordingly, according to a second combustion air ratio of the exhaust gas.

The 2 shows several curves 15, 16, 17, 18, 19 and 20 in four diagrams. Curves 15 to 20 each show a conversion efficiency for one of several exhaust gas components. Curve 15 describes the conversion efficiency for carbon monoxide, curve 16 the conversion efficiency for hydrocarbons, curve 17 the conversion efficiency for ammonia, curve 18 the conversion efficiency for molecular hydrogen, curve 19 the conversion efficiency for nitrogen monoxide and curve 20 the conversion efficiency for molecular oxygen, each over a combustion air ratio, namely in a range of 0.9 ≤ λ ≤ 1.1. The conversion efficiency is used to determine an output content of the respective exhaust gas component from an input content. The input content is present in the exhaust gas upstream of the exhaust aftertreatment device 12, the output content is present downstream of the exhaust aftertreatment device 12.

The two upper diagrams indicate the conversion performance at a lower first temperature of the exhaust gas aftertreatment device 2, while the two lower diagrams indicate a higher second temperature. Purely as an example, the first temperature is 300°C and the second temperature is 500°C. The two left-hand diagrams show the conversion performance for the individual exhaust gas components after changing the combustion air ratio from rich to lean, while the two right-hand diagrams show the conversion performance after changing the combustion air ratio from lean to rich.

A comparison of the two upper diagrams for the first temperature shows a significant difference in conversion efficiency depending on whether the combustion air ratio was changed from rich to lean (left diagram) or from lean to rich (right diagram). Thus, the conversion efficiency for hydrocarbons, shown in curve 16, is significantly lower for the change in the combustion air ratio from rich to lean for λ < 1 than for the change in the combustion air ratio from lean to rich. The same applies to the conversion efficiency for carbon monoxide, as shown in curve 16.

The two lower diagrams for the second temperature, however, show that at the higher temperature, there is no or at most only a slight difference between the conversion performance, regardless of whether the combustion air ratio was changed from rich to lean or from lean to rich. However, it is clear that the temporal progression of the combustion air ratio should be taken into account when determining the conversion performance and thus also when determining the output content from the input content based on the conversion performance in order to achieve the highest possible accuracy.

The diagrams shown here relate to a new exhaust gas aftertreatment device 12 which is relatively new or has only been in operation for a short time. For an exhaust gas aftertreatment device 12 which is older or has only been in operation for a longer time, different conversion performances may result. In particular, with such an exhaust gas aftertreatment device 12, the dependence of the conversion performance on the temporal progression of the combustion air ratio occurs not only at the lower first temperature, but also at the higher second temperature, albeit to a lesser extent than at the first temperature. Depending on the age of the exhaust gas aftertreatment device 12, it is therefore provided to take into account the temporal progression of the combustion air ratio even at high temperatures of the exhaust gas aftertreatment device 12 in order to achieve good accuracy.

LIST OF REFERENCE SYMBOLS:

1

drive device

2

drive unit

3

Exhaust tract

4

cylinder

5

Inlet valve

6

outlet valve

7

Fresh gas tract

8

compressor

9

exhaust gas turbocharger

10

turbine

11

exhaust pipe

12

Exhaust aftertreatment system

13

1. Lambda sensor

14

2. Lambda sensor

15

Course

16

Course

17

Course

18

Course

19

Course

20

Course

Claims (9)

Method for operating a drive device (1) for a motor vehicle, which drive unit (2) has an exhaust gas-generating drive unit (2) and an exhaust gas aftertreatment device (12) designed as a vehicle catalytic converter for aftertreating the exhaust gas, wherein by means of a catalytic converter model, an output content of the at least one exhaust gas component present downstream of the exhaust gas aftertreatment device (12) is determined at least temporarily from an input content of at least one exhaust gas component of the exhaust gas present upstream of the exhaust gas aftertreatment device (12) using a temperature of the exhaust gas aftertreatment device (12), wherein a time profile of a combustion air ratio in the exhaust gas is additionally taken into account when determining the output content, characterized in that an influencing factor of a catalyst poison on the exhaust gas aftertreatment device (12) is calculated from the time profile and is taken into account when determining the output content. Procedure according to Claim 1 , characterized in that several values of the combustion air ratio are measured at intervals in time by means of a lambda probe (13, 14) and stored in the curve. Method according to one of the preceding claims, characterized in that the curve comprises values for the combustion air ratio over a period of at least 1 second, at least 2 seconds or at least 5 seconds. Method according to one of the preceding claims, characterized in that the course of the combustion air ratio is taken into account as a function of the temperature of the exhaust gas aftertreatment device (12). Method according to one of the preceding claims, characterized in that the course of the combustion air ratio is taken into account as a function of a state of the exhaust gas aftertreatment device (12). Method according to one of the preceding claims, characterized in that the at least one exhaust gas component or an exhaust gas component different from the at least one exhaust gas component is used as the catalyst poison. Method according to one of the preceding claims, characterized in that the output content is determined from the input content using a conversion performance for the at least one exhaust gas component, the conversion performance being lower the greater the proportion of a combustion air ratio corresponding to a lack of oxygen in the time profile. Drive device (1) for a motor vehicle, in particular for carrying out the method according to one or more of the preceding claims, wherein the drive device (1) has a drive unit (2) generating exhaust gas and an exhaust gas aftertreatment device (12) designed as a vehicle catalyst for aftertreating the exhaust gas, and is provided and designed to determine, by means of a catalyst model, at least temporarily from an input content of at least one exhaust gas component of the exhaust gas present upstream of the exhaust gas aftertreatment device (12), an output content of the at least one exhaust gas component present downstream of the exhaust gas aftertreatment device (12) using a temperature of the exhaust gas aftertreatment device (12), wherein the drive device (1) is further provided and designed to additionally take into account a time profile of a combustion air ratio in the exhaust gas when determining the output content, characterized in that the drive device (1) is further provided and designed to calculate an influencing factor of a catalyst poison on the exhaust gas aftertreatment device (12) from the time profile and to determine the starting salary must be taken into account. Computer program product, comprising instructions which cause the drive device (1) to Claim 8 the procedure according to one or more of the Claims 1 until 7 executes.

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