DE102022211964A1 - Method for operating an internal combustion engine - Google Patents

Abstract

The invention relates to a method (200) for operating an internal combustion engine (110), wherein at least one catalyst (122) for converting an exhaust gas of the internal combustion engine (110) is arranged in an exhaust system (120) downstream of the internal combustion engine (110), and wherein the method (200) comprises: determining (210) a current temperature of the at least one catalyst (122), determining (220) a current conversion capacity of the at least one catalyst (122) on the basis of the determined temperature, determining (230) a power threshold value for the operation of the internal combustion engine (110) on the basis of the determined conversion capacity, and operating (240) the internal combustion engine (110) such that the power threshold value is not exceeded. Furthermore, a computing unit (130) and a computer program for carrying out such a method (200) are proposed.

Description

The present invention relates to a method for operating an internal combustion engine as well as a computing unit and a computer program for carrying out the method.

Background of the invention

To achieve legally prescribed emission limits, three-way catalysts (TWC) can be used, which enable the conversion of the relevant gaseous pollutants NO _x , HC and CO into harmless products such as N ₂ , H ₂ O and CO _2. In order for these catalytic reactions to take place as intended, the temperatures in the catalyst must generally exceed the so-called light-off temperature of typically 300-400°C. As soon as this is reached or exceeded, the catalyst converts the relevant pollutants almost completely (so-called catalyst window).

In order to achieve this state as quickly as possible, so-called internal engine catalyst heating measures can be used. The efficiency of the gasoline engine is reduced by late ignition angles, thus increasing the exhaust gas temperature and the enthalpy input into the catalyst. At the same time, combustion stability can be ensured by adapted injection strategies (e.g. multiple injections).

In addition to these internal engine catalyst heating measures, external catalyst heating measures can also be used, for example by means of electrically heated catalysts or exhaust gas burners. Such external heating measures are, for example, used in the DE 41 32 814 A1 and the DE 195 04 208 A1 described.

Disclosure of the invention

According to the invention, a method for operating an internal combustion engine as well as a computing unit and a computer program for carrying out the method are proposed with the features of the independent patent claims. Advantageous embodiments are the subject of the subclaims and the following description.

The invention involves determining a temperature-dependent conversion capacity of an exhaust gas catalyst and deriving therefrom a limitation requirement with regard to the operation of the internal combustion engine in order to reduce the raw emissions of the internal combustion engine in the event of incomplete conversion capacity so that the emission of pollutants into the environment is avoided.

In detail, a method according to the invention for operating an internal combustion engine, wherein at least one catalyst for converting an exhaust gas of the internal combustion engine is arranged in an exhaust system downstream of the internal combustion engine, comprises determining a current temperature of the at least one catalyst, determining a current conversion capacity of the at least one catalyst on the basis of the determined temperature, determining a power threshold for the operation of the internal combustion engine on the basis of the determined conversion capacity, and operating the internal combustion engine such that the power threshold is not exceeded.

In some embodiments of the invention, the power threshold value includes a maximum speed of the internal combustion engine and/or a maximum torque/cylinder charge that can be provided by the internal combustion engine and/or a maximum exhaust gas mass flow generated by the internal combustion engine. These are particularly relevant control parameters that a control unit for internal combustion engines can usually process or implement directly.

In some embodiments of the invention, the power threshold value can be determined as a proportion of a nominal power value (e.g. nominal torque, nominal power, cut-off speed, exhaust gas mass flow at nominal power, maximum design-related acceleration, etc.) of the internal combustion engine. The method can thus be applied directly to a large number of internal combustion engines without having to determine specific control parameters for each one. This makes implementation easier, since only the nominal data of the respective internal combustion engine needs to be stored in order to be able to use the method.

In particular, the method can include determining a proportion of at least one exhaust gas component in the exhaust gas of the internal combustion engine and taking the proportion into account when determining the power threshold value. In this way, the emission of certain pollutants can be reduced in a targeted manner and the limitation of the operation of the internal combustion engine can be restricted to a necessary level, which increases the usability of the internal combustion engine.

In some embodiments of the method, an exhaust enthalpy of the exhaust gas of the internal combustion engine is set depending on the power threshold. This means that the method can be used not only to limit emissions, but also to control catalyst heating measures, which reduces the overall control effort, since no separate control is then required for this.

The power threshold value can be determined in particular by taking into account at least one emission threshold value which designates a maximum acceptable emission of an exhaust gas component at an outlet of the exhaust system.

A computing unit according to the invention, e.g. a control unit of a motor vehicle, is set up, in particular in terms of programming, to carry out a method according to the invention.

The implementation of a method according to the invention in the form of a computer program or computer program product with program code for carrying out all method steps is also advantageous, since this causes particularly low costs, in particular if an executing control device is also used for other tasks and is therefore already present. Finally, a machine-readable storage medium is provided with a computer program stored on it as described above. Suitable storage media or data carriers for providing the computer program are in particular magnetic, optical and electrical storage devices, such as hard disks, flash memories, EEPROMs, DVDs, etc. It is also possible to download a program via computer networks (Internet, intranet, etc.). Such a download can be wired or cable-bound or wireless (e.g. via a WLAN network, a 3G, 4G, 5G or 6G connection, etc.).

Further advantages and embodiments of the invention emerge from the description and the accompanying drawings.

The invention is illustrated schematically in the drawing using an embodiment and is described below with reference to the drawing.

Short description of the drawings

• 1 shows a schematic representation of a vehicle as it can be used in embodiments of the invention.
• 2 shows an embodiment of the invention in a highly simplified representation in the form of a block diagram.
• 3 shows exemplary curves of operating variables of an exhaust system of an internal combustion engine, as they can occur within the scope of embodiments of the invention.
• 4 shows a possible implementation of the invention in the form of a highly simplified flow chart.

Embodiment(s) of the invention

In 1 a vehicle as can be used within the scope of the invention is shown schematically and designated overall by 100. The vehicle 100 comprises an internal combustion engine 110, for example a gasoline or diesel engine, whereby in principle all conceivable types of reciprocating piston and rotary piston engines can be used. In the example shown here, the internal combustion engine 110 comprises six cylinders with reciprocating pistons indicated in the drawing. The vehicle 100 further comprises an exhaust system 120, which has a catalyst 122 and a further exhaust gas purification unit 124, for example a further catalyst or a particle filter, as well as a computing unit 130, which is set up to control the internal combustion engine 110 and the exhaust system 120 and is connected to them in a data-conducting manner. Furthermore, the computing unit 130 in the example shown is connected in a data-conducting manner to sensors 112, 121, 123, 127, which measure the operating parameters of the internal combustion engine 110 and/or the exhaust system. 120. For example, the sensors can be lambda sensors (in particular sensors 121, 127) and/or temperature sensors 112, 123.

It is understood that in addition to and/or instead of the sensors mentioned, further or other sensors may be present, which may not be shown in the figure. The exhaust system 120 may also have further cleaning components, such as further particle filters and/or further catalysts, which are not shown here for the sake of simplicity.

In the example shown here, the computing unit 130 comprises a data memory 132 in which, for example, computing rules and/or parameters (e.g. threshold values, characteristics of the internal combustion engine 110 and/or the exhaust system 120 or similar) can be stored.

The internal combustion engine 110 drives wheels 140 to move the vehicle 100 and can also be driven by the wheels 140 in certain operating phases (e.g. so-called overrun operation).

In 2 An advantageous embodiment of the invention is shown using a highly simplified block diagram and is designated overall by 200. For example, the embodiment 200 can be implemented as a method or computer program. In the following, a method 200 is assumed in order to explain the invention in more detail.

In the description of the method 200, references to vehicle components are made to the 1 However, this should not be understood as meaning that the method 200 is exclusively related to the vehicle 100 shown in 1 shown vehicle 100. Rather, this is a possible application that is used here only for explanatory purposes. In principle, the method 200 can be used for a large number of different exhaust systems and is by no means limited to use in vehicles or even to exhaust systems of internal combustion engines.

In 3 exemplary curves of operating variables of an exhaust system of an internal combustion engine, as they can occur within the scope of embodiments of the invention, in particular of the method 200, are shown in the form of diagrams 300, 310. References to such operating variables in the description of the method 200 can in particular also refer to the 3 parameters shown.

The two diagrams 300 and 310 share a common time axis t (abscissa). Diagram 300 shows temperatures (curves 301, 302, 303, with reference 304, which indicates a target temperature up to which external and/or motor-driven heating is used) at different locations on a catalyst (e.g. catalyst 122). In diagram 310, a catalytically active portion of the catalyst volume (curve 311), a limitation requirement factor 312 and a heating requirement factor 313 are plotted over time t (and depending on the temperatures 301, 302, 303 shown in diagram 300).

In a first step 210 of the method 200, as described in 2 As shown, a current temperature of the catalyst 122 is determined. This can be done, for example, by means of a temperature sensor 123, or by means of a temperature model in which, for example, operating data of the internal combustion engine 110 can be processed. The temperature determined in this way can, for example, designate a current temperature at an inlet of the catalyst 122 or a temperature distribution across the volume of the catalyst 122.

In a second step 220, a current conversion capacity of the catalyst 122 is determined based on the temperature determined in step 210. In this case, for example, a catalytically active portion of the total volume of the catalyst can be determined, whereby in particular a partial activity that already exists below an actual light-off temperature can be taken into account. Furthermore, in this step 220, an age-related light-off shift of the catalyst 122 can also be taken into account. As a result of step 220, for example, a maximum convertible exhaust gas mass flow or a relative catalyst activity, in particular based on a nominal output of the catalyst 122, can be output.

In a step 230, a power threshold value for the operation of the internal combustion engine 110 is determined on the basis of the conversion capacity determined in step 220. For example, such a power threshold value can be defined as the maximum permissible exhaust gas mass flow, as the maximum through the internal combustion engine 110 available torque or as a relative value of a rated power of the internal combustion engine 110, whereby it should be emphasized that other relevant quantities than such a power threshold value can also be determined.

As an alternative to a performance threshold, a limitation requirement or limitation requirement factor (as in 3 shown as curve 312), whereby such a limitation requirement factor 312 can be defined, for example, as the reciprocal of the above-mentioned relative value of the nominal power. In particular, the limitation requirement factor 312 can be determined as 1 (or 100%) if the conversion capacity (or the relative active catalyst volume 311) is 0, i.e. the catalyst 122 is not able to convert exhaust gas, and/or as 0 (or 0%) if the catalyst 122 has its nominal conversion capacity (i.e. in particular is completely warmed through; relative active catalyst volume 311 = 1).

For example, such a limitation requirement factor fac _EngLimnDmd can be calculated using the following formula: $$ea{c}_{EnGLimnDmd}=\frac{ra{t}_{ActvCatVOl,Des}-ra{t}_{ActvCatVOl}}{ra{t}_{ActvCatVOl,Des}-ra{t}_{ActvCatVOl,Min}}$$

Here, rat _{ActvCatVol, Des} denotes the target conversion capacity of the catalyst 122 (or 100%), rat _ActCatVol the current conversion capacity 311 (here expressed as a proportion of the active catalyst volume) and rat _{ActvCatVol, Min} a minimum conversion capacity required for conversion (for example, for converting an exhaust gas mass flow generated by the internal combustion engine 110 when idling). Alternatively or additionally, a currently maximum permissible exhaust gas mass flow ṁ _{Exh, Avbl} can be derived from the current conversion capacity 311.

A possible implementation, for example as a computer program, is also in 4 presented in the form of a highly simplified flow chart and labelled with 400 in total. In the 4 In the implementation 400 shown, the temperature is calculated in a sub-functionality 403 to determine the catalytically active portion of the catalyst volume rat _ActvCatVol 408. This portion 408 is then calculated with a maximum convertible exhaust gas mass flow ṁ _{Exh, max} 402 and a minimum exhaust gas mass flow ṁ _{Exh, min} 401 (e.g. required for idle cat heating) to obtain a currently maximum permissible exhaust gas mass flow ṁ _{Exh, Avbl} 421. $${\dot{m}}_{ExH,Avbl}={\dot{m}}_{ExH,max}\cdot {\eta }_{COnv}\approx {\dot{m}}_{ExH,max}\cdot \left(1-ea{c}_{EnGLimnDmd}\right)$$

Alternatively, instead of this threshold value 421 with respect to the exhaust gas mass flow, a torque threshold or power threshold can also be specified.

For nominal value rat _{ActvCatVol, Des} =1 and minimum value ra _{tActvCatVol, Min} = the following results: $$ea{c}_{EnGLimnDmd}=1-ra{t}_{ActvCatVOl}\approx 1-{\eta }_{COnv}$$

Here, η _Conv ≈ rat _ActvCatVol ≈ (1 - fac _EngLimnDmd ) denotes the relative conversion efficiency, with a value of 1 corresponding to a complete conversion. ṁ _{Exh, max} denotes a maximum convertible exhaust gas mass flow when the catalyst 122 is completely heated (η _Conv ≈ 1).

When determining the limitation requirement factor 312, a maximum permissible unconverted exhaust gas mass flow ṁ _{Exh, NotConvertable, max} (e.g. based on the maximum legally permitted pollutant emissions) can be taken into account. This results in the currently maximum permissible exhaust gas mass flow ṁ _{Exh, Avbl} as: $${\dot{m}}_{ExH,Avbl}=\frac{{\dot{m}}_{ExH,NOtCOnvertable,ma\mathrm{<figure-callout\; id="1"\; label="x"\; filenames="DE102022211964A1\_0020.png"\; state="\{\{state\}\}">x</figure-callout>}}}{1-{\eta }_{COnv}}\approx {\left[\frac{{\dot{m}}_{ExH,NOtCOnvertable,max}}{ea{c}_{EnGLimnDmd}}\right]}_{{\dot{m}}_{ExH,min}}^{{\dot{m}}_{ExH,max}}$$

Alternatively, maximum permissible emission limits at the outlet of the exhaust system ṁ _{Emi, TP, Max} (e.g. legally defined) can be used to calculate the limitation requirement factor based on measured or modelled raw emissions ṁ _{Emi, Raw} . In this case, the permissible The most critical emission component or the minimum of several critical emission components (e.g. CO, HC, NOx, NH3) can be used to calculate the exhaust gas mass flow ṁ _{Exh, Avbl} . $${\dot{m}}_{Emi,TP,Max}={\dot{m}}_{Emi,Raw}\cdot \left(1-{\eta }_{COnv}\right)={\dot{m}}_{Emi,Raw}\cdot ea{c}_{EnGLimnDmd}$$

ermittelt werden. Es versteht sich, dass hierbei sowohl zeitbasierte, als auch streckenbasierte Grenzwerte verwendet werden können, wobei bei streckenbasierten Grenzwerten zusätzlich die aktuelle Geschwindigkeit des Fahrzeugs mit in den Limitierungsbedarfsfaktor fac_EngLimnDmd eingerechnet werden muss. In einigen Ausgestaltungen kann auch eine Mindestgeschwindigkeit vorgesehen sein, unterhalb derer mit zeitbasierten Grenzwerten $\left[\frac{mg}{s}\right]$

und ab derer mit streckenbasierten Grenzwerten $\left[\frac{mg}{km}\right]$

gearbeitet wird. Dies hat den Vorteil, dass allzu starke Limitierungen aufgrund niedriger Geschwindigkeit abgemildert werden, was sich insgesamt positiv auf die Fahrbarkeit eines so gesteuerten Fahrzeugs 100 auswirkt.The raw emissions ṁ _{Emi, Raw} can also be calculated based on a raw emission concentration rat _{Emi, Raw} [ppm] and the molar mass ratio of emission component and total exhaust gas $w_{Emi}\left[\frac{k{G}_{Emi}}{k{G}_{ExH}}\right]$

It is understood that both time-based and distance-based limit values can be used here, whereby with distance-based limit values the current speed of the vehicle must also be included in the limitation requirement factor fac _EngLimnDmd . In some embodiments, a minimum speed can also be provided below which time-based limit values $\left[\frac{mG}{s}\right]$

and from those with distance-based limits $\left[\frac{mG}{km}\right]$

This has the advantage that excessive limitations due to low speed are mitigated, which has an overall positive effect on the drivability of a vehicle 100 controlled in this way.

Based on the power threshold value (or limitation requirement factor) determined in this way, the internal combustion engine 110 is controlled in a control step 240 such that the power threshold value determined in step 230 is not exceeded (or the limitation requirement is met). In 2 Three scenarios are indicated, which refer to different positions of the performance threshold.

$$P_{i,\text{max}}=M_{i,\text{max}}\cdot 2\pi n={\dot{m}}_{b,max}\cdot H_u\cdot {\eta }_i$$

$$M_{i,max}=\frac{{\dot{m}}_{Exh,Avbl}\cdot H_u\cdot {\eta }_i}{\left(1+\lambda \cdot L_{st}\right)\cdot 2\pi n}$$

$$P_{i,max}=\frac{{\dot{m}}_{Exh,Avbl}\cdot H_u\cdot {\eta }_i}{1+\lambda \cdot L_{st}}$$

A fuel mass flow is typically set to control the internal combustion engine 110. The maximum permissible exhaust gas mass flow ṁ _{Exh, Avbl} currently results in the maximum usable fuel mass flow ṁ _{b, max} and thus the maximum available power P _{i, max} (or max. torque M _{i, max} ) of the internal combustion engine 110: $${\dot{m}}_{b,max}=\frac{{\dot{m}}_{ExH,A\mathrm{<figure-callout\; id="1"\; label="v\; b\; l"\; filenames="DE102022211964A1\_0020.png"\; state="\{\{state\}\}">v</figure-callout>}bl}}{1+\lambda \cdot L_{st}}$$

$$P_{i,\text{Max}}=M_{i,\text{Max}}\cdot 2\pi n={\dot{m}}_{b,max}\cdot H_u\cdot {\eta }_i$$

$$M_{i,max}=\frac{{\dot{m}}_{ExH,Avbl}\cdot H_u\cdot {\eta }_i}{\left(1+\lambda \cdot L_{st}\right)\cdot 2\pi n}$$

$$P_{i,max}=\frac{{\dot{m}}_{ExH,Avbl}\cdot H_u\cdot {\eta }_{\mathrm{<figure-callout\; id="1"\; label="i"\; filenames="DE102022211964A1\_0020.png"\; state="\{\{state\}\}">i</figure-callout>}}}{1+\lambda \cdot L_{st}}$$

$$

zu einer Konstante K_M bzw. K_P (Wertangaben jeweils für einen typischen PKW-Benzin-Ottomotor) zusammengefasst werden: $$\begin{array}{r}{M}_{i,max}\left[Nm\right]={\left[\frac{K_M\cdot {\dot{m}}_{Exh,Avbl}\left[\frac{kg}{h}\right]}{n_{Eng}\left[rpm\right]}\right]}_{Tr{q}_{min}}^{Tr{q}_{max}}\\ \text{mit }{K}_M=\frac{H_u\left[MJ/kg\right]\cdot {\eta }_i}{\left(1+\lambda \cdot L_{st}\right)\cdot 2\pi }\cdot \frac{1/3600\left[h/s\right]}{1/60\left[min/s\right]}\approx 2500\left[\frac{J\cdot h}{kg\cdot min}\right]\end{array}$$

$$\begin{array}{r}{P}_{i,\text{max}}\left[W\right]={\left[K_P\cdot {\dot{m}}_{Exh,Avbl}\left[\frac{kg}{h}\right]\right]}_{P_{min}}^{P_{max}}\\ \text{mit }{K}_P=\frac{H_u\left[MJ/kg\right]\cdot {\eta }_i}{1+\lambda \cdot L_{st}}\ast 1/3600\left[\frac{h}{s}\right]\approx 280\left[\frac{J\cdot h}{kg\cdot s}\right]\end{array}$$

The quantities calorific value H _u (≈42.7 MJ/kg), lambda λ (≈1), stoichiometric air-fuel mass ratio L _st (≈14.7 kg _L /kg _b ) and efficiency of the internal combustion engine η _i (≈0.33) can be calculated with the other constant terms (including unit conversion for $n_{EnG}\left(\frac{U}{s}\right)=n_{EnG}\left(rpm\right)\ast \frac{1}{60}\frac{s}{min},{\dot{m}}_{AbG}\left(\frac{kG}{s}\right)={\dot{m}}_{AbG}\left(\frac{kG}{H}\right)\ast \frac{1}{3600}\frac{H}{s}$

$$

to a constant K _M or K _P (values given for a typical car petrol engine): $$\begin{array}{r}{M}_{i,max}\left[Nm\right]={\left[\frac{K_M\cdot {\dot{m}}_{ExH,Avbl}\left[\frac{kG}{H}\right]}{n_{EnG}\left[rpm\right]}\right]}_{Tr{q}_{min}}^{Tr{q}_{max}}\\ \text{with}{K}_M=\frac{H_u\left[MJ/kG\right]\cdot {\eta }_i}{\left(1+\lambda \cdot L_{st}\right)\cdot 2\pi }\cdot \frac{1/3600\left[H/s\right]}{1/60\left[min/s\right]}\approx 2500\left[\frac{J\cdot H}{kG\cdot min}\right]\end{array}$$

$$\begin{array}{r}{P}_{i,\text{Max}}\left[W\right]={\left[K_P\cdot {\dot{m}}_{ExH,Avbl}\left[\frac{kG}{H}\right]\right]}_{P_{min}}^{P_{max}}\\ \text{with}{K}_P=\frac{H_u\left[MJ/kG\right]\cdot {\eta }_i}{1+\lambda \cdot L_{st}}\ast 1/3600\left[\frac{H}{s}\right]\approx 280\left[\frac{J\cdot H}{kG\cdot s}\right]\end{array}$$

The maximum torque limit (M _{i, max} ) or relative filling limit (rl _max ) can thus be specified in a simple approach in a map using the limitation requirement factor fac _EngLimnDmd and the speed n _Eng . In some implementations of the invention, the permissible exhaust gas mass flow ṁ _{Exh, Avbl} , which depends on the maximum permissible emission limits at the outlet of the exhaust system ṁ _{Emi, TP, Max,} can be used as a reference for specifying the limiting maps. In alternative embodiments, these can also be implemented directly and used as a replacement for such maps in order to reduce the amount of data required to determine the power threshold accordingly. The maximum available torque M _{i, max} is limited to an upper (Trq _max ) or lower (Trq _min ) torque limit (e.g. due to the design). Likewise, during the calculation, the maximum available power P _{i, max} is limited to an upper (P _max ) or lower (P _min ) power limit.

In a first scenario 242, the maximum available power/torque is so low that the internal combustion engine 110 cannot be operated (eg P _i,max so low that stable operation of the internal combustion engine 110 is not guaranteed). In such a case, for example, an external heating device such as an electric heating disk or an exhaust gas burner can be used to heat the catalyst 122 until a minimum required conversion capacity or a minimum permissible exhaust gas mass flow is reached.

• Der Motorstart wird freigegeben, sobald der zulässige Abgasmassenstrom 421 eine bedatbare Massenstromschwelle 411 überschreitet. Alternativ lässt sich aus einer Startbedingung 404, insbesondere einem bei Betrieb der Brennkraftmaschine 110 minimal abgegebenen Drehmoment MD_{EngStrt, Thd}, sowie Parametern 405 der Brennkraftmaschine 110, insbesondere der oben beschriebenen empirischen Konstante K_M, (erwünschter bzw. minimal möglicher) Drehzahl der Brennkraftmaschine n_Eng, sowie dem Wirkungsgrad η der Brennkraftmaschine 110, ein bei einem Start der Brennkraftmaschine 110 benötigter Abgasmassenstrom ṁ_{Exh, EngStrt, Thd} (in 4 mit 411 bezeichnet) berechnen. Um den Einfluss des Verbrennungswirkungsgrads zu berücksichtigen kann für die so ermittelte Motorstartverzögerungsschwelle ein Referenz-Katheizwirkungsgrad berücksichtigt werden. Durch Vergleich mit dem ermittelten maximal zulässigen Abgasmassenstrom ṁ_{EXh, max} wird eine Freigabe bzw. Sperrung flg_EngStrt 422 des Starts der Brennkraftmaschine 110 ermittelt.

This is also provided analogously in implementation 400:

• The engine start is enabled as soon as the permissible exhaust gas mass flow 421 exceeds a dataable mass flow threshold 411. Alternatively, an exhaust gas mass flow _{ṁ Exh , EngStrt, Thd required} when starting the internal combustion engine 110 (in 4 designated with 411). In order to take the influence of the combustion efficiency into account, a reference catalyst heating efficiency can be taken into account for the engine start delay threshold determined in this way. By comparing it with the determined maximum permissible exhaust gas mass flow ṁ _{EXh, max,} an enabling or blocking flg _EngStrt 422 of the start of the internal combustion engine 110 is determined.

In a second scenario 244, the exhaust gas mass flow threshold value 412 or power threshold value 406 allows the internal combustion engine 110 to start, but accelerating the vehicle 100 would result in the power threshold value being exceeded. In such a case, a departure delay can be initiated, for example by blocking the release flg _ICEDoD for coupling the internal combustion engine 110 to the wheels 140.

Furthermore, in the scenario 244, the internal combustion engine 110 can be controlled in such a way that it generates an exhaust gas with an increased exhaust gas enthalpy compared to normal operation in order to support the heating of the catalyst 122. In this case, for example, an ignition angle and/or an air-fuel ratio that is unfavorable from the point of view of the efficiency of the internal combustion engine 110 is set (engine-based catalyst heating). Period 342 in 3 can, for example, correspond to this second scenario 244. [motorized catalyst heating is active as long as the heating requirement > 0, usually even after the departure delay has expired]

• Die motorische Abfahrt wird freigegeben, sobald der zulässige Abgasmassenstrom 421 eine bedatbare Massenstromschwelle 412 überschreitet. Alternativ kann die zur Abfahrt minimal erforderliche Leistung P_{ICEDoD, Thd} der Brennkraftmaschine 110 (mit Abfahrtsbedingung 406 bezeichnet) und weiteren Parametern 407 der Brennkraftmaschine 110, insbesondere der oben erläuterten Konstante K_P und dem Wirkungsgrad η, in einen zur motorischen Abfahrt benötigten Abgasmassenstrom ṁ_{Exh, ICEDoD, Thd} (in 4 mit 412 bezeichnet) umgerechnet werden. Hier wäre der Katheizwirkungsgrad der exklusiven Momentenreserve geeignet, um einen unbeabsichtigten Betriebsstopp der Brennkraftmaschine zu verhindern. Ein Vergleich dieses erwarteten Abgasmassenstroms 412 mit dem maximal zulässigen Abgasmassenstrom ṁ_{Exh, max} ergibt eine Freigabe bzw. Sperrung flg_ICEDoD 423 einer Abfahrt des Fahrzeugs 100 (bzw. einer Kopplung der Brennkraftmaschine 110 an die Räder 140).

This scenario is also analogous in the implementation 400 in 4 shown:

• The motorized departure is enabled as soon as the permissible exhaust gas mass flow 421 exceeds a dataable mass flow threshold 412. Alternatively, the minimum power P _{ICEDoD, Thd} of the internal combustion engine 110 required for departure (designated as departure condition 406) and further parameters 407 of the internal combustion engine 110, in particular the constant K _P explained above and the efficiency η, can be converted into an exhaust gas mass flow ṁ _{Exh, ICEDoD, Thd} required for the motorized departure (in 4 denoted by 412). Here the catalyst heating efficiency of the exclusive Torque reserve suitable to prevent an unintentional stop of the internal combustion engine. A comparison of this expected exhaust gas mass flow 412 with the maximum permissible exhaust gas mass flow ṁ _{Exh, max} results in an approval or blocking of a departure of the vehicle 100 (or a coupling of the internal combustion engine 110 to the wheels 140) by _ICEDoD 423.

In a third scenario 246, in which the power threshold allows departure, the mechanical coupling of the internal combustion engine 110 and wheels 140 can be released and the vehicle 100 can be moved, whereby depending on the specific power threshold, a power value of the internal combustion engine 110, for example a torque delivered by the internal combustion engine, can be limited, so that the maximum possible torque due to the design is only released after the full conversion capacity has been reached (see also time period 344 and 346 in 3 ).

In the 4 In the implementation 400 shown, the power threshold value or the limitation requirement factor after departure clearance 423 can be determined from the maximum permissible exhaust gas mass flow 421, as already described in detail above.

QUOTES INCLUDED IN THE DESCRIPTION

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Cited patent literature

• DE 4132814 A1 [0004]
• DE 19504208 A1 [0004]

Claims (9)

Method (200) for operating an internal combustion engine (110), wherein at least one catalyst (122) for converting an exhaust gas of the internal combustion engine (110) is arranged in an exhaust system (120) downstream of the internal combustion engine (110), and wherein the method (200) comprises: determining (210) a current temperature of the at least one catalyst (122), determining (220) a current conversion capacity of the at least one catalyst (122) based on the determined temperature, determining (230) a power threshold value for the operation of the internal combustion engine (110) based on the determined conversion capacity, and operating (240) the internal combustion engine (110) such that the power threshold value is not exceeded. Procedure (200) according to Claim 1 , wherein the power threshold value comprises a maximum speed of the internal combustion engine (110) and/or a maximum torque that can be provided by the internal combustion engine (110) and/or a maximum exhaust gas mass flow generated by the internal combustion engine (110). Procedure (200) according to Claim 1 or 2 , comprising determining a proportion of at least one exhaust gas component in the exhaust gas of the internal combustion engine (110) and taking the proportion into account when determining (230) the power threshold value. Method (200) according to one of the preceding claims, wherein an exhaust gas enthalpy of the exhaust gas of the internal combustion engine (110) is adjusted as a function of the power threshold value. Method (200) according to one of the preceding claims, wherein the power threshold value is determined as a proportion of a nominal power value of the internal combustion engine (110). Method (200) according to one of the preceding claims, wherein the determination (230) of the power threshold value takes place taking into account at least one emission threshold value (which designates a maximum acceptable emission of an exhaust gas component at an outlet of the exhaust system (120). Computing unit (130) which is configured to carry out all method steps of a method (200) according to one of the preceding claims. Computer program which causes a computing unit (130) to carry out all method steps of a method according to one of the Claims 1 until 6 when executed on the computing unit (130). Machine-readable storage medium with a computer program stored thereon in accordance with Claim 8 .

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