Exhaust gas aftertreatment of an internal combustion engine with an exhaust gas catalytic converter having an oxygen storage

Abstract

An internal combustion engine, which can in particular be provided for driving a motor vehicle and which has a combustion engine (1) and an exhaust line (8) with an exhaust gas aftertreatment device (11), wherein the exhaust gas aftertreatment device (11) comprises an exhaust gas catalytic converter (12) with an oxygen storage, the internal combustion engine being operated such that at the start of the ignition operation of the combustion engine (1) after an unignited inertial operation or non-operation, the magnitude of the exhaust gas mass flow generated by the combustion engine (1) is temporarily controlled as a function of the filling level of the oxygen storage.

Description

Field of the Invention

[0001] The invention relates to a method for operating an internal combustion engine having a combustion engine and an exhaust gas line with an exhaust gas aftertreatment device, wherein the exhaust gas aftertreatment device includes an exhaust gas catalytic converter with an oxygen storage. Background Art

[0002] An exhaust gas catalytic converter (such as in particular a three-way catalytic converter) can have an oxygen storage, i.e. a defined capacity for storing oxygen. In the lean operation of the combustion engine of an internal combustion engine (which includes such a three-way catalytic converter in the exhaust gas line), the excess oxygen contained in the raw exhaust gas is stored in the oxygen storage, while in rich operation, the stored oxygen is used for the aforementioned conversion. Such a regular alternating storage and extraction of oxygen also takes place in a combustion engine which operates with a substantially stoichiometric air-fuel ratio (i.e. with λ≈1) as is common in an externally ignited and quantity-regulated gasoline engine. In order to achieve such a stoichiometric air-fuel ratio, the residual oxygen content in the exhaust gas is usually analyzed by means of at least one so-called oxygen sensor and used to adjust the air-fuel mass ratio of the subsequent combustion process. However, such a reaction regulation results in the actual air-fuel ratio fluctuating within a relatively narrow range around the stoichiometric air-fuel ratio. In this regard, it is known to actively implement a so-called natural frequency regulation for the air-fuel ratio, in which the combustion engine is alternately operated slightly rich (i.e. with a slightly sub-stoichiometric air-fuel ratio (λ<1)) and slightly lean (i.e. with a slightly supra-stoichiometric air-fuel ratio (λ>1)). Then, in the case of a defined deviation from the stoichiometric air-fuel ratio, a conversion between rich operation and lean operation is carried out.

[0003] If the combustion engine is operated without ignition for a period of time, such operation of the internal combustion engine may cause problems. This may be the case: the combustion engine is driven (coasting operation (Schubbetrieb)) or the combustion engine is stopped, for example, within the scope of the automatic stop function, wherein the combustion engine does not stop immediately with the end of the fuel injection, but also performs some rotation of the output shaft (crankshaft). In such an unfired operation, the combustion engine conveys exhaust gas, which mainly consists of air and therefore contains a large amount of oxygen, into the exhaust gas line. This oxygen is stored in the oxygen storage device and thus causes the filling level of the oxygen storage device to increase, usually until the oxygen storage capacity of the oxygen storage device is completely exhausted. If the combustion engine is then ignited again, there is no (sufficient) oxygen storage capacity available for a relatively short but not negligible period of time, which can lead to an increase in nitrogen oxide emissions. In order to avoid this situation, such combustion engines are often basically operated with excess for a short time after the start of the ignition operation, which is, however, associated with the problem of increased fuel consumption and therefore increased CO2 emissions. Furthermore, due to the simultaneous presence of unburned hydrocarbons and nitrogen oxides, an undesirable formation of relevant amounts of ammonia (NH 3 ) may occur here.

[0004] DE 102 23 733 A1 discloses supplying fuel to a combustion engine for a short time after non-operation and in order to restart operation as set, without igniting the fuel. The fuel diverted into the exhaust gas line leads to the withdrawal of oxygen stored in the oxygen storage device, thereby ensuring that the oxygen storage device has a sufficiently low filling level when the combustion engine restarts the ignition operation. However, the problem of increased fuel consumption and thus increased CO2 emissions is not solved thereby.

[0005] US 2006 / 0021330 A1 describes a method in which, after restarting operation of the combustion engine, the oxygen content of the exhaust gas is measured at a first point upstream of the exhaust catalytic converter and at a second point downstream of the exhaust catalytic converter, and the control of the combustion engine is influenced as a function of the difference in the measured values.

[0006] Furthermore, US 2007 / 0163540 A1 discloses a method for operating an internal combustion engine with an emphasis on exhaust gas aftertreatment. Summary of the invention

[0007] The object of the present invention is to avoid as far as possible the problems associated with a high filling level of the oxygen accumulator at the start of operation of the combustion engine.

[0008] This object can be achieved by the method according to the invention. Advantageous embodiments of the method are apparent from the subsequent description of the invention.

[0009] According to the invention, an internal combustion engine is operated as follows. The internal combustion engine can in particular be provided for driving a motor vehicle and has a combustion engine and an exhaust gas line with an exhaust gas aftertreatment device. The exhaust gas aftertreatment device includes an exhaust gas catalytic converter with an oxygen storage, such that at the start of the ignition operation of the combustion engine after an unignited coasting operation or non-operation, the magnitude of the exhaust gas mass flow generated by the combustion engine is temporarily controlled or influenced (variably) as a function of the filling level of the oxygen storage.

[0010] Accordingly, the operation of the combustion engine or the drive power generated thereby (which has a direct influence on the mass flow of the exhaust gas generated by the combustion engine) is carried out not only as a function of the current power requirement, but at least also taking into account the filling level of the oxygen storage. It can thus be provided that when the filling level of the oxygen storage is above a limit value, the operating function of the combustion engine (for example, specifically with respect to the theoretical driving torque and / or the theoretical combustion chamber filling and / or the theoretical mass flow of fresh gas and / or exhaust gas) is restricted such that a relatively small exhaust gas mass flow occurs (compared to the corresponding operation without the restriction). Such a relatively small exhaust gas mass flow can contribute to this: that the capacity of the oxygen storage is not completely exhausted despite the relatively high filling level at the start of the ignition operation, before the reconditioning of the oxygen storage by normal operation with filling and emptying is carried out. Normal operation is understood here to mean that the exhaust gas aftertreatment by means of the exhaust gas catalytic converter is no longer influenced by the oxygen introduced into the exhaust gas line due to the unignited coasting operation or non-operation of the combustion engine. By the method according to the invention, it is also possible to largely prevent, as soon as possible or immediately after the start of the operation of the combustion engine, the escape (slip) of nitrogen oxides through the exhaust gas catalytic converter.

[0011] The restriction of the operating function of the combustion engine can also lead to a restriction of the drive power generated by the combustion engine, so that in principle it is possible that the combustion engine provides a lower drive power due to this restriction than the drive power that the combustion engine would provide without the corresponding restriction in the power requirement. To keep such a restriction or its influence as low as possible, the restriction is only implemented if it is actually required, which can be ensured by defining the limit value. If the filling level of the nitrogen oxide storage is below the limit value at the start of the ignition operation, the corresponding restriction can accordingly be cancelled, and thus the operation of the combustion engine or the drive power generated thereby can be controlled, if necessary, only as a function of the current power demand, but at least not as a function of the filling level of the oxygen storage.

[0012] The limit value does not have to be fixedly defined here. Instead, it may be meaningful to change the limit value variably according to the operating parameters of the internal combustion engine, so that at the beginning of the first ignition operation after the first coasting operation or non-operation, a different limit value can be set than at the beginning of the second ignition operation after the second coasting operation or non-operation. It can be considered, for example, that the raw exhaust gas generated by the combustion engine can have different components and therefore also different amounts of harmful substances and especially nitrogen oxides according to a plurality of operating parameters of the internal combustion engine (such as the operating temperature of the combustion engine, the level of power requirement, the rate of exhaust gas recirculation set if necessary, etc.). Accordingly, relatively high limit values can be set for certain operating parameters of the internal combustion engine, because when considering these operating parameters, it can be assumed that the remaining relatively small oxygen storage capacity of the oxygen storage is sufficient to avoid the escape of nitrogen oxides through the exhaust gas catalytic converter. Conversely, for certain other operating parameters, relatively low limit values may be required in order to avoid such an escape of nitrogen oxides with sufficient reliability.

[0013] Furthermore, the limitation of the operating functions of the combustion engine (if such limitation is necessary) should also only be implemented to the extent that this is necessary to achieve the desired goal (i.e. to avoid the escape of nitrogen oxides through the exhaust gas catalytic converter as much as possible). Accordingly, it can preferably be provided that the higher the filling level of the oxygen storage device, the greater the limitation of the operating functions of the combustion engine is selected. When the ignition operation of the combustion engine is started with, for example, a completely filled oxygen storage device (and correspondingly an oxygen storage device capacity of substantially zero), a significantly more pronounced limitation of the operating functions of the combustion engine can thus be provided than would be provided if the oxygen storage device (which still has a not negligible oxygen storage device capacity) was filled beyond the limit value.

[0014] The exhaust gas catalytic converter can in particular be a three-way catalytic converter which can catalytically support the removal of carbon monoxide (CO), nitrogen oxides (NO X ) and unburned hydrocarbons (HC) into carbon dioxide (CO2), nitrogen (N2) and water (H2O) at least once. Such a three-way catalytic converter may also have other exhaust gas aftertreatment functions, in particular the function of a particle filter. A three-way catalytic converter with a particle filter function is also generally referred to as a four-way catalytic converter. According to the present invention, such a four-way catalytic converter is an extended stage of a three-way catalytic converter and accordingly also falls within the definition of a three-way catalytic converter according to the present invention. In order to construct a four-way catalytic converter, it can be provided that a filter body that functions as a particle filter is provided with a coating that functions as a three-way catalytic converter.

[0015] If an exhaust gas aftertreatment device of an internal combustion engine has a plurality of exhaust gas catalytic converters with oxygen storage, the exhaust gas catalytic converter whose oxygen storage capacity is used as a parameter in the control of the magnitude of the exhaust gas mass flow according to the invention is in particular the exhaust gas catalytic converter closest to the combustion engine in the exhaust gas line, and in the case of a three-way catalytic converter design, at least the three-way catalytic converter closest to the combustion engine.

[0016] In order to avoid a negative impact on the performance or operating characteristics of the entire internal combustion engine due to a limitation of the operating function of the combustion engine, it can preferably be provided that the limitation of the operating function of the combustion engine is at least partially compensated by an electric motor drivingly connected to the combustion engine of the internal combustion engine. Thus, if, for example, the power output of the combustion engine is limited or restricted to a value below the theoretical value according to the power requirement of the internal combustion engine due to the filling level of the oxygen storage, it can be provided that the difference between the power output of the combustion engine and the power requirement of the internal combustion engine is compensated by the electric motor.

[0017] The electric motor can, for example, be an electric traction motor which can also be provided in a motor vehicle (hybrid vehicle) comprising an internal combustion engine for ensuring the driving drive of the motor vehicle when required. Here, the traction motor can also be designed such that the traction motor temporarily completely causes the driving drive of the motor vehicle.

[0018] The non-operation and subsequent ignition operation can in particular be caused by an automatic start-stop function of the combustion engine. Since such a start-stop function of the combustion engine can be carried out relatively frequently during the operation of the internal combustion engine, it can be particularly advantageous with regard to the harmful substance emission characteristics of the internal combustion engine to control the magnitude of the exhaust gas mass flow generated by the combustion engine according to the filling level of the oxygen storage when the ignition operation of the combustion engine then starts.

[0019] If, during the inertia operation, a change in the gear stage of a (manual or automatic) gearshift transmission drivingly connected to the combustion engine is carried out, in particular a change towards a smaller gear stage (which has a smaller transmission ratio), then in particular the problem of possible escape of nitrogen oxides through the exhaust gas catalytic converter can also occur, since in the case of such a change in the gear stage, a relatively high load requirement can be imposed on the combustion engine for a short time, and the load requirement can be accompanied by a correspondingly high exhaust gas mass flow.

[0020] According to a preferred embodiment of the method according to the invention, it can be provided that the combustion engine initially runs with a targeted excess (also by means of a corresponding adjustment of the combustion air ratio) at the start of the ignition operation, and subsequently runs with a stoichiometric combustion air ratio. Accordingly, the combustion engine can in principle be designed to run with a stoichiometric combustion air ratio, wherein the temporarily excessive running at the start of the ignition operation serves, in addition to controlling and in particular limiting the magnitude of the exhaust gas mass flow generated by the combustion engine according to the filling level of the oxygen storage, also to extract oxygen from the oxygen storage. Thereby, it is possible to cause the escape of nitrogen oxides through the exhaust gas catalytic converter to the greatest extent possible and in particular also with the least possible limitation of the exhaust gas mass flow generated by the combustion engine and the resulting limitation of the operating function of the combustion engine.

[0021] The combustion engine of an internal combustion engine operating according to the invention can in particular be a (externally ignited and quantity-regulated) gasoline engine. However, there is also the possibility that the combustion engine is a (self-igniting and quality-regulated) diesel engine or a combination of a gasoline engine and a diesel engine (for example, a combustion engine with homogeneous charge compression ignition). The combustion engine can here operate not only with liquid fuels (i.e., diesel or gasoline), but also with gaseous fuels (in particular natural gas, LNG or LPG).

[0022] The invention also relates to a motor vehicle, in particular a wheel-based and non-rail-connected motor vehicle (preferably a passenger car or a truck), which has an internal combustion engine operating according to the invention. Here, the combustion engine of the internal combustion engine can in particular be provided for (directly or indirectly) providing the driving power for the motor vehicle. Description of the Drawings

[0023] The invention will be explained in more detail below on the basis of the design examples and embodiments shown in the drawings. Among them:

[0024] Figure 1 An internal combustion engine suitable for carrying out the method according to the invention is shown in a simplified illustration;

[0025] Figure 2 The temporal courses of the theoretical driving power required by the internal combustion engine, the actual driving power output by the combustion engine of the internal combustion engine, and the filling level of the oxygen storage of the exhaust gas catalytic converter of the internal combustion engine are shown; and

[0026] Figure 3 The course of the operating factor n with respect to the filling level F of the oxygen storage is shown. Detailed Description of the Embodiment

[0027] Figure 1Shows an internal combustion engine for a motor vehicle suitable for performing the method according to the present invention. The internal combustion engine includes a combustion engine 1, which is designed, for example, in the form of a reciprocating piston engine having four cylinder openings 2 arranged in a row. The cylinder openings 2 delimit combustion chambers 4 by means of reciprocating pistons 3 guided therein and cylinder heads respectively. During the operation of the combustion engine 1 and thus the internal combustion engine, fresh gas is supplied to these combustion chambers 4 via a fresh gas line 5, wherein the supply of fresh gas is controlled by means of intake valves 6 assigned to the respective combustion chambers 4. The fresh gas is only or mainly air drawn from the surroundings. The exhaust gas generated during the combustion of the mixture consisting of fresh gas and fuel directly injected into the combustion chambers 4 by means of fuel injectors 7 is discharged via an exhaust gas line 8 of the internal combustion engine, wherein the discharge of the exhaust gas is controlled by means of exhaust valves 9 assigned to the respective combustion chambers 4. The ignition of the mixture in the combustion chamber is carried out by means of an electric ignition device 10, which, for example, generates an ignition spark (spark plug). Here, the exhaust gas flows through an exhaust gas aftertreatment device 11, which is provided for removing the components of the exhaust gas regarded as harmful substances from the exhaust gas or converting them into harmless components.

[0028] The exhaust gas aftertreatment device 11 includes an exhaust gas catalytic converter 12 with an oxygen storage. The exhaust gas catalytic converter can be designed in the form of a three-way catalytic converter.

[0029] During the operation of the combustion engine 1, the amount of fresh gas to be supplied to the combustion engine 1 and the amount of fuel to be introduced into the respective combustion chambers 4 by means of fuel injectors 7 for each working cycle are adjusted in a targeted manner according to the specific operating state of the combustion engine 1, which is particularly defined by the required load and operating speed. For this purpose, in terms of fresh air, the operating position of a throttle valve (not shown) integrated into the fresh gas line 5 and / or a variable valve drive (not shown) can be changed, by means of which the intake valves 6 can be variably actuated. The combustion engine 1 operates at least temporarily on average with a stoichiometric combustion air ratio (λ≈1), such that the oxygen supplied to the combustion chambers 4 basically exactly corresponds to the amount required for the thermal conversion of the fuel supplied simultaneously during this period. Since it is not technically possible to operate the combustion engine 1 with a constant stoichiometric combustion air ratio in terms of control technology, the combustion engine 1 operates alternately slightly rich and slightly lean, such that on average an operation with a stoichiometric combustion air ratio occurs over the observed period.

[0030] During slightly lean operation, the excess oxygen contained in the raw exhaust gas is stored in the oxygen storage, while during slightly rich operation, the stored oxygen is used to convert carbon monoxide (CO), nitrogen oxides (NO X) and unburned hydrocarbons (HC) are converted into carbon dioxide (CO2), nitrogen (N2) and water (H2O).

[0031] When the combustion engine 1 runs without ignition during inertial operation, the combustion engine conveys the exhaust gas, which consists mainly of air and thus contains a large amount of oxygen, into the exhaust gas line 8. This oxygen is stored in the oxygen storage of the exhaust gas catalytic converter 12 and thus causes an increase in the filling level of the oxygen storage. If the combustion engine 1 then runs with ignition again, this can lead to a situation where there is no (sufficient) oxygen storage capacity of the oxygen storage available for use within a relatively short but non-negligible period of time, which can lead to an increase in nitrogen oxide emissions.

[0032] To avoid this, if the filling level of the oxygen storage exceeds the (upper) limit value F1, the combustion engine 1 runs so restrictedly at the start of ignition operation that a relatively small mass flow of the raw exhaust gas generated by the combustion engine 1 occurs. Thereby, the oxygen storage of the exhaust gas catalytic converter 12 is loaded with a correspondingly smaller flow rate of nitrogen oxides, whereby it is possible to avoid as much as possible a complete depletion of the capacity of the oxygen storage and the escape of nitrogen oxides through the exhaust gas catalytic converter 12. The relevant amount of nitrogen oxides in the raw exhaust gas of the combustion engine 1 usually cannot be avoided here. If, as is preferably provided, the combustion engine 1 runs temporarily slightly rich at the start of ignition operation, this serves on the one hand to generate as little nitrogen oxide as possible and on the other hand to cause the extraction of oxygen from the oxygen storage by the targeted provision of unburned hydrocarbons and carbon monoxide.

[0033] Figure 2 The process is illustrated on the basis of a diagram in which, first of all, the theoretical drive power P S required by the internal combustion engine is shown as a function of time (curve 13), the actual drive power P I output by the combustion engine 1 of the internal combustion engine is also shown as a function of time (curve 14), and the filling level F of the oxygen storage is shown as a function of time (curve 15). The combustion engine 1 is not running here at first (P S and P I are zero respectively), whereby the filling level F of the oxygen storage is at a value above the upper limit value F1, which is the Figure 2 upper limit of the filling level range 16 shown in. Within this filling level range 16, the oxygen loading of the oxygen storage is regarded as optimal.

[0034] At time point t1, the ignition operation of the combustion engine is (again) started. Thereby, the theoretical drive power 13 is increased to a limit value in the short term. If the combustion engine 1 is operated in such a way that its actual drive power 14 follows the change process of the theoretical drive power 13 as precisely as possible, this can lead to a further increase in the filling level F of the oxygen storage or at least only a relatively slow decrease due to the corresponding rapid increase in the exhaust gas mass flow. According to the invention, it can thus be arranged that the generation of the actual drive power P of the combustion engine 1 is restricted for a relatively short time period (between t1 and t2), and thus the mass flow of the raw exhaust gas generated by the combustion engine is restricted in order to achieve as quickly as possible reaching or falling below the limit value F1 of the filling level F of the oxygen storage. This is the case at time point t2. Then the restriction of the operating function of the combustion engine 1 is cancelled, whereby the actual drive power P of the combustion engine 1 I then relatively quickly approaches the theoretical drive power P I . Then adaptation (Angleichung) is achieved at time point t3. From this time point t3 onwards, the combustion engine 1 can be operated normally again, i.e., in particular, with a substantially stoichiometric combustion air ratio, thereby causing an alternating change process of the filling level F of the oxygen storage, where this change process permanently remains within the optimal filling level range 16. S . Then according to Figure 2 In order to compensate for the restriction of the operating function of the combustion engine 1 (which results in the actual drive power P of the combustion engine 1

[0035] being below the theoretical drive power P of the internal combustion engine I ), so that the internal combustion engine as a whole provides an actual drive power corresponding to the theoretical drive power P S if an electric motor is drivingly connected to the combustion engine 1, then the corresponding operation of the electric motor can be used to compensate for the difference between the theoretical drive power P of the internal combustion engine S and the actual drive power P of the combustion engine 1 S . This difference corresponds to I the compensation area 17 shown shaded in Figure 2 , and this compensation area is located between the change processes 13, 14 of the theoretical drive power P S and the actual drive power P I during the time period between t1 and t3.

[0036] Figure 3 The figure shows the change process of the operating factor n (vertical axis) with respect to the filling level F of the oxygen storage of the exhaust gas catalytic converter, where this operating factor n corresponds to the reciprocal of the limiting factor. In addition, in Figure 3Such a filling level range 16 is shown in which the oxygen loading of the oxygen storage is considered optimal. If the filling level F of the oxygen storage is within this filling level range 16, an operating factor n of 1 is achieved, which corresponds to no restriction of the operating function of the combustion engine 1. However, if the filling level F of the oxygen storage exceeds the upper limit value F1, the operating factor n decreases to a value less than 1, which corresponds to a restriction of the operating function of the combustion engine 1. Here, the operating factor n decreases from the upper limit value F1 until the filling level of 100%, in which case the oxygen storage basically no longer has any oxygen storage capacity. The smallest operating factor n can then correspond to a value between, for example, 0.4 and 0.5.

[0037] In addition, Figure 3 it is also shown that when the filling level of the oxygen storage is below the lower limit value F2, the operating function of the combustion engine 1 can be restricted. This restriction can also consist in only allowing a relatively small mass flow of the raw exhaust gas generated by the combustion engine 1. Thereby, it can be avoided that the exhaust gas generated by the combustion engine 1, which initially runs rich at the start of the ignition operation, contains such a large amount of unburned hydrocarbons and carbon monoxide that its oxidation cannot take place to a sufficient extent by means of the exhaust gas catalytic converter 12 using the oxygen stored in the oxygen storage, and thereby a so-called rich breakthrough (Fettdurchbruch) through the exhaust gas catalytic converter 12 can occur. In order to effect the restriction when the filling level F of the oxygen storage is below the lower limit value F2, it can also be provided that the operating factor n decreases from the lower limit value F2 until the filling level of 0%, in which case the oxygen storage basically no longer stores oxygen. In this case, the smallest operating factor n can then also correspond to a value between 0.4 and 0.5. In particular, if there is the possibility of compensating for the restriction of the operating function of the combustion engine by means of an electric motor drivingly connected to the combustion engine, even smaller values of the operating factor n are possible.

[0038] List of reference numerals

[0039] 1 Combustion engine

[0040] 2 Cylinder opening

[0041] 3 Reciprocating piston

[0042] 4 Combustion chamber

[0043] 5 Fresh gas line

[0044] 6 Inlet valve

[0045] 7 Fuel injector

[0046] 8 Exhaust gas line

[0047] 9 Exhaust valve

[0048] 10 Ignition device

[0049] 11 Exhaust gas post-treatment device

[0050] 12 Three-way catalytic converter

[0051] 13 Variation process of the theoretical drive power of an internal combustion engine

[0052] 14 Variation process of the actual drive power of a combustion engine

[0053] 15 Variation process of the filling level of an oxygen storage

[0054] 16 Filling level range with optimal oxygen loading

[0055] 17 Compensation area

[0056] P S Theoretical drive power of an internal combustion engine

[0057] P I Actual drive power of a combustion engine

[0058] F Filling level of an oxygen storage

[0059] F1 Upper limit value of the filling level of an oxygen storage

[0060] F2 Lower limit value of the filling level of an oxygen storage

[0061] n Operating factor.

Claims

1. A method for operating an internal combustion engine, which internal combustion engine has a combustion engine (1) and an exhaust gas line (8) with an exhaust gas aftertreatment device (11), wherein, The exhaust gas aftertreatment device (11) comprises an exhaust gas catalytic converter (12) with an oxygen storage, characterized in that at the start of the ignition operation of the combustion engine (1) after an unignited inertial operation or non-operation of the combustion engine (1), the magnitude of the exhaust gas mass flow generated by the combustion engine (1) is temporarily controlled as a function of the filling level (F) of the oxygen storage, wherein when the filling level (F) of the oxygen storage is above a limit value (F1), the operating function of the combustion engine (1) is restricted such that a relatively small exhaust gas mass flow occurs, wherein the limit value (F1) is variably selected as a function of the operating parameters of the internal combustion engine.

2. The method according to claim 1, characterized in that, The higher the filling level (F) of the oxygen storage, the greater the restriction of the operating function of the combustion engine (1) is selected.

3. The method according to claim 1, characterized in that, The restriction of the operating function of the combustion engine (1) is at least partially compensated for by an electric motor drivingly connected to the combustion engine (1).

4. The method according to claim 1, characterized in that The non-operation and subsequent ignition operation are produced by an automatic start-stop function of the combustion engine (1).

5. The method according to claim 1, characterized in that, During the inertial operation, a change in the gear stage of a gearshift transmission drivingly connected to the combustion engine (1) is carried out.

6. The method according to claim 5, characterized in that, The change to a smaller gear stage is carried out.

7. The method according to claim 1, wherein The combustion engine (1) runs temporarily rich at the start of the ignition operation and subsequently runs with a stoichiometric combustion air ratio.

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