AT521758B1 - Method and arrangement of a gasoline engine with an improved exhaust aftertreatment by means of an overrun fuel cut-off strategy - Google Patents

Abstract

The invention relates to a method and a spark-ignition engine arrangement, in which the spark-ignition engine (1) is operated in an operating phase which comprises a normal operating phase and an overrun phase, fuel and air being converted into an exhaust gas in the spark-ignition engine (1) in the normal operating phase, the Otto engine (1) in the normal operating phase is preferably operated in a lambda window around λ=1, with the overrun phase being formed by an unfired overrun phase and/or a fired overrun phase, with the gas flowing through the at least one main catalytic converter (3) being low in oxygen in the fired overrun phase , in particular essentially oxygen-free, wherein the exhaust gas that was generated in the gasoline engine (1) before or during the transition from the normal operating phase to the unfired overrun phase is supplied to the gasoline engine (1) in the unfired overrun phase via an exhaust gas recirculation line (9), or wherein the Otto engine (1) in the unfired overrun phase is supplied via an exhaust gas recirculation line (9) with that exhaust gas which was generated in the Otto engine (1) before or during the transition from a fired overrun phase to the unfired overrun phase, the in the unfired overrun phase the amount of oxygen in the exhaust gas flowing through the main catalytic converter (3) and all other catalytic converters of the exhaust aftertreatment system (2) is less than or equal to the oxygen storage capacity of the main catalytic converter (3) and all other catalytic converters.

Description

Description

METHOD AND GASOLINE ENGINE ARRANGEMENT WITH AN IMPROVED EXHAUST AFTERTREATMENT THROUGH AN OVERRUN STRATEGY

The invention relates to a method and an Otto engine assembly according to the preambles of the independent claims.

Different methods for operating a gasoline engine are known from the prior art.

For example, methods are known in which the gasoline engine to reduce fuel consumption or to lower the combustion temperature part of the exhaust gas produced is admixed on the intake side via an exhaust gas recirculation system.

Methods are also known in which the fuel supply to the gasoline engine is intentionally temporarily interrupted by a so-called deceleration fuel cut-off when the gasoline engine is not supposed to deliver any power. These processes essentially serve to save fuel and to reduce CO2 emissions when coasting - colloquially also referred to as engine braking.

[0005] Especially in these overrun phases or when there are gaps in load, the exhaust gas aftertreatment system is flushed with the air pumped through the gasoline engine. As a result, on the one hand, thermal stresses can arise in the exhaust gas aftertreatment components of the exhaust gas aftertreatment system. On the other hand, oxygen can be stored in the catalytic layers of the exhaust gas aftertreatment components, as a result of which the efficiency of exhaust gas aftertreatment components that are sensitive to oxygen, in particular the efficiency of a 3-way catalytic converter, is impaired. In order to avoid emission peaks, the gasoline engine according to the prior art is first operated sub-stoichiometrically or richly when combustion resumes, as a result of which the oxygen stored in the exhaust gas components can be oxidized. This rich operation of the gasoline engine can result in a brief increase in fuel consumption, which partially counteracts the savings during overrun cut-off. This rich operation of the petrol engine can result in localized and sometimes damaging areas of heat in the catalytic converters and a short-term increase in fuel consumption.

Furthermore, with conventional methods, the efficiency of the exhaust gas aftertreatment system, in particular the 3-way catalytic converter, is only reduced for a short time if it is flushed with air, for example during overrun phases.

[0007] Further methods for exhaust gas aftertreatment using an overrun strategy are known, for example, from US 2011072795 A1, GB 2560758 A and WO 2008079772 A2.

It is an object of the invention to overcome the disadvantages of the prior art. In particular, it is the object of the invention to create a method and a spark-ignition engine arrangement which enables low fuel consumption, which is particularly relevant for everyday customer use, and lowest pollutant emissions. Furthermore, it is among other things the object of the invention to reduce or preferably eliminate a possible situational cross-influencing of the specified target values, namely the fuel consumption and the pollutant emissions. In addition, it is the object of the invention to come closer to the so-called vision of "zero impact emissions" in order to provide the end customer with an economical petrol engine arrangement on the one hand and on the other hand to protect the environment by, preferably as far as possible, falling below the pollutant emission laws prescribed by the legislator .

The object of the invention is achieved in particular by the features of the independent patent claims.

The invention relates to a method for operating an Otto engine arrangement in an operating phase that includes a normal operating phase and an overrun phase, the Otto engine arrangement comprising an Otto engine and an exhaust gas aftertreatment system with at least one main catalytic converter, fuel and air becoming an exhaust gas in the Otto engine in the normal operating phase be implemented, with the Otto engine being operated and/or controlled in the normal operating phase preferably in a lambda window around A=1, with the overrun phase being formed by at least one unfired overrun phase and/or at least one fired overrun phase, and with in the fired overrun phase the den Gas flowing through the main catalytic converter is low in oxygen, in particular essentially free of oxygen, and in particular the exhaust gas is a stoichiometric or substoichiometric, in particular phased substoichiometric, combustion.

According to the invention, in the unfired overrun phase, the gasoline engine is fed via an exhaust gas recirculation line that exhaust gas which was generated in the gasoline engine before or during the transition from the normal operating phase to the unfired overrun phase, or that the gasoline engine is fed that exhaust gas in the unfired overrun phase is supplied via an exhaust gas recirculation line, which was generated before or during the transition from a fired overrun phase to the unfired overrun phase in the gasoline engine.

The Otto engine arrangement can be the Otto engine arrangement of an internal combustion engine, in particular the Otto engine arrangement of a motor vehicle.

In the normal operating phase, the Otto engine is preferably operated and/or regulated in a lambda window around A=1. This means that the gasoline engine may oscillate around a lambda value X of 1.0 and is operated and/or regulated with a lambda value A in the range from 0.9 to 1.1, preferably from 0.95 to 1.05. Provision can be made for the spark-ignition engine to be operated and/or regulated in its normal operating phase in phases or permanently under- or over-stoichiometrically or rich or lean. Under these conditions, the exhaust gas aftertreatment components of the Otto engine arrangement allow a sufficiently high, in particular the best possible, raw emission conversion.

It is preferably provided that the gas flowing through the main catalytic converter in the normal operating phase is low in oxygen, in particular essentially free of oxygen.

[0015] This may mean that both in the normal operating phase and in the overrun phases, a sufficient, preferably the greatest possible, degree of conversion of the pollutants by the exhaust gas aftertreatment components should be ensured overall. As a result, a sufficiently high reduction in pollutants can be made possible in or after the overrun phases, in particular in the fired overrun phase. In particular, it is provided that at no time does the pollutant emission conversion level of the exhaust gas aftertreatment system fall below a pollutant emission conversion level threshold value, below which there is no longer a sufficiently high level of pollutant emission reduction. If necessary, provision is made for the pollutant emission conversion level threshold value to be as high as possible, in particular in a range as close to 100% as possible.

The exhaust aftertreatment system comprises at least one main catalytic converter, in particular a catalytic converter that acts as a 3-way catalytic converter. In particular, the exhaust gas generated in the gasoline engine flows through the main catalytic converter of the exhaust aftertreatment system.

[0017] Furthermore, the exhaust aftertreatment system can contain the main catalytic converter(s) and optionally one or more primary catalytic converter(s) and/or one or more secondary catalytic converter(s), in particular one or more oxidation catalytic converter(s), which comprises/have an oxidation catalytic converter coating/s. and/or one or more heated catalytic converter(s) and/or one or more petrol engine particle filters, in particular coated in gaseous form with effective exhaust aftertreatment, and/or one or more NOx storage catalytic converter(s) and/or one or more exhaust gas aftertreatment component(s), which include a NOx storage catalytic converter - Coating include, and / or one or more SCR system / s and / or one or more exhaust gas aftertreatment component / s, which include an SCR coating, and / or comprise a secondary air injection.

Furthermore, the exhaust gas aftertreatment system can consist of the main catalytic converter(s) and optionally one or more pre-catalytic converter(s) and/or one or more secondary catalytic converter(s), in particular one or more oxidation catalytic converter(s), which includes an oxidation catalytic converter coating/s , and/or one or more heated catalytic converter(s) and/or one, in particular one or more gaseous exhaust gas aftertreatment-effectively coated, Otto engine particle filter and/or one or more NOx storage catalytic converter(s) and/or one or more exhaust gas aftertreatment component(s) which have a NOx storage catalytic converter coating include, and / or one or more SCR system / s and / or one or more exhaust gas aftertreatment component / s, which includes an SCR coating / s, and / or a secondary air injection may be formed.

In the operating phase, which includes the normal operating phase and the overrun phase, the Otto engine arrangement is in operation. In the normal operating phase, fuel and air can be introduced into the combustion chambers of the cylinders of the Otto engine and converted into exhaust gas by combustion.

In the overrun phase, the Otto engine can be towed by the mass of the internal combustion engine that is in motion. This overrun phase can include at least one unfired overrun phase and/or at least one fired overrun phase.

In the unfired overrun phase, the fuel supply to the Otto engine is usually interrupted and air is pumped through the Otto engine. This air, which is pumped by the petrol engine, flows through the exhaust aftertreatment system, which means that fuel consumption can be reduced on the one hand, but on the other hand the main catalytic converter can have a short-term reduced conversion rate as a result of the unfired overrun phase, since its oxygen storage tank is filled up, among other things.

In the fired overrun phase, the fuel supply to the Otto engine is only reduced and, for example, only that amount of fuel is introduced into the combustion chambers of the Otto engine that is required to convert the amount of oxygen introduced by the air into a low-oxygen, in particular essentially oxygen-free, implement exhaust gas. In particular, in the fired overrun phase, stoichiometric or sub-stoichiometric combustion takes place in the combustion chambers of the gasoline engine. On the one hand, this can prevent and/or reduce the negative effects of oxygen flooding on the oxygen-sensitive exhaust gas aftertreatment components of the exhaust aftertreatment system, but on the other hand, fuel is also consumed in overrun mode and CO₂ is emitted as a result.

In order to resolve the conflict of objectives mentioned above between low average fuel consumption, which is particularly relevant to customer everyday use, and the lowest pollutant emissions, and to reduce or preferably eliminate any possible cross-influencing of the target values mentioned, the spark-ignition engine is, according to the invention, in the unfired overrun phase before or during the transition to the unfired overrun phase generated and low-oxygen, essentially oxygen-free exhaust gas supplied. The low-oxygen, essentially oxygen-free, exhaust gas can have been generated in the normal operating phase or in the fired overrun phase. In particular, the low-oxygen, essentially oxygen-free exhaust gas generated before or during the transition to the unfired overrun phase is pumped in a circuit during the unfired overrun phase through the cylinders of the Otto engine driven by the crankshaft.

This preferably means that the generated low-oxygen, essentially oxygen-free, exhaust gas in the unfired overrun phase flows through the gasoline engine and then, if necessary, the exhaust gas aftertreatment system, in particular the main catalytic converter, and is then fed back to the gasoline engine through the exhaust gas recirculation line.

By operating the gasoline engine in an unfired overrun phase, in which, however, the low-oxygen, essentially oxygen-free, exhaust gas is circulated, it may be possible to reduce both fuel consumption and pollutant emissions. In particular, this makes it possible in the unfired overrun phase essentially

not to consume any fuel and still keep the oxygen content in the main catalytic converter of the exhaust aftertreatment system low.

It is thus possible with the method according to the invention to resolve the aforementioned conflict of objectives.

In the context of the present invention, the at least one main catalytic converter or the main catalytic converter is to be understood as meaning one or more catalytic converter(s), in particular a plurality of main catalytic converters, which essentially have the same effect and/or function. If appropriate, the at least one main catalytic converter comprises one or more catalytic converter(s), in particular one or more primary or secondary catalytic converter(s) and/or one or more heated catalytic converter(s). The at least one main catalytic converter may be formed from one or more main catalytic converter(s), in particular from one or more primary and/or secondary catalytic converter(s) and/or from one or more heated catalytic converter(s). At least one of the abovementioned catalysts is preferably coated with a 3-way coating.

If necessary, it is provided that the method is executed automatically, in particular in a control unit of a motor vehicle and/or by a control unit of a motor vehicle, in a controlled and/or regulated manner.

If necessary, it is provided that the fuel supply is or is stopped in the unfired overrun phase.

This makes it possible to reduce the fuel consumption in the unfired overrun phase essentially to zero.

Optionally, it is provided that in the normal operating phase and/or in the fired overrun phase, the exhaust gas of the Otto engine is fed to the main catalytic converter, and that this main catalytic converter is designed or acts as a 3-way catalytic converter.

In particular, it can be provided that in the normal operating phase and/or in the fired overrun phase, the exhaust gas of the Otto engine generated by the combustion of fuel flows through the exhaust gas aftertreatment system, in particular the main catalytic converter, and is then released to the environment and/or into the exhaust gas recirculation line entry.

If necessary, it is provided that the oxygen content of the exhaust gas in the exhaust aftertreatment system or that the oxygen content of the exhaust gas flowing through the exhaust aftertreatment system in the overrun phase, in particular in the unfired overrun phase, essentially corresponds to the oxygen content of the exhaust gas flowing through the exhaust aftertreatment system in the normal operating phase or in the fired overrun phase corresponds.

If necessary, it is provided that the oxygen content of the exhaust gas in the main catalytic converter or that the oxygen content of the exhaust gas flowing through the main catalytic converter in the unfired overrun phase essentially corresponds to the oxygen content of the exhaust gas flowing through the main catalytic converter in the normal operating phase or in the fired overrun phase.

This means that the exhaust gas generated before or during the transition to the unfired overrun phase in the normal operating phase or in the fired overrun phase by the combustion of the fuel in the combustion chambers of the cylinders of the Otto engine is circulated in the unfired overrun phase.

In particular, the exhaust gas supplied to the gasoline engine in the unfired overrun phase first flows through the exhaust gas recirculation line, then through the gasoline engine and then, if necessary, through the exhaust gas aftertreatment system, in particular the main catalytic converter. The exhaust gas can be pumped around as long as the unfired overrun phase lasts. This means that, if necessary, the exhaust gas several times or continuously through the exhaust gas recirculation line, the gasoline engine and, if necessary, the exhaust gas aftertreatment system, in particular

the main catalyst, can be pumped.

In one embodiment it is provided that the exhaust gas generated before or during the transition to the unfired overrun phase is introduced via the exhaust gas recirculation line into the gasoline engine and then back into the exhaust gas recirculation line for supplying the exhaust gas generated to the gasoline engine.

In one embodiment, it is provided that the exhaust gas generated before or during the transition to the unfired overrun phase is fed via the exhaust gas recirculation line into the gasoline engine, then into the exhaust gas aftertreatment system, in particular the main catalytic converter, and then back into the exhaust gas recirculation line for feeding the exhaust gas generated to the Otto engine is introduced.

If necessary, it is provided that the oxygen content of the exhaust gas in the main catalytic converter is less than 5% by volume or essentially zero in the normal operating phase and/or in the overrun phase, in particular in the unfired overrun phase, or that the oxygen content of the Main catalytic converter and at least one additional catalytic converter of the exhaust gas aftertreatment system in the normal operating phase and/or in the overrun phase, in particular in the unfired overrun phase, is less than 5% by volume or essentially zero, or that the oxygen content of the in the main catalytic converter and all other catalytic converters the exhaust gas located in the exhaust aftertreatment system is less than 5% by volume or essentially zero in the normal operating phase and/or in the overrun phase, in particular in the unfired overrun phase.

Optionally, it is provided that the oxygen content of the exhaust gas flowing through the main catalytic converter is less than 5% by volume or essentially zero in the normal operating phase and/or in the overrun phase, in particular in the unfired overrun phase.

If necessary, it is provided that the oxygen content of the exhaust gas flowing through the main catalytic converter and at least one further catalytic converter of the exhaust gas aftertreatment system is less than 5% by volume or essentially zero in the normal operating phase and/or in the overrun phase, in particular in the unfired overrun phase . If necessary, it is provided that the oxygen content of the exhaust gas flowing through the main catalytic converter and all other catalytic converters of the exhaust aftertreatment system is less than 5% by volume or essentially zero in the normal operating phase and/or in the overrun phase, in particular in the unfired overrun phase.

In particular, it is provided that the oxygen content of the exhaust gas generated in the normal operating phase and the fired overrun phase is low and, in particular, is less than 5 percent by volume.

If necessary, it is provided that the amount of oxygen in the exhaust gas flowing through the main catalytic converter in the unfired overrun phase is less than or equal to the oxygen storage capacity of the main catalytic converter, or that the amount of oxygen in the exhaust gas flowing through the main catalytic converter and at least one further catalytic converter of the exhaust gas aftertreatment system in the unfired overrun phase is less than or equal to is equal to the oxygen storage capacity of the main catalytic converter and the at least one additional catalytic converter, or that the amount of oxygen in the exhaust gas flowing through the main catalytic converter and all additional catalytic converters of the exhaust gas after-treatment system in the unfired overrun phase is less than or equal to the oxygen storage capacity of the main catalytic converter and all additional catalytic converters.

Optionally, it is provided that the amount of oxygen in the exhaust gas that is in the main catalytic converter in the unfired overrun phase is less than or equal to the oxygen storage capacity of the main catalytic converter.

If necessary, it is provided that the amount of oxygen in the exhaust gas located in the unfired overrun phase in the main catalytic converter and at least one further catalytic converter of the exhaust gas aftertreatment system is less than or equal to the oxygen storage capacity of the

Main catalyst and the at least one other catalyst is.

The invention provides that the amount of oxygen in the exhaust gas in the unfired overrun phase in the main catalyst and all other catalysts of the exhaust gas aftertreatment system is less than or equal to the oxygen storage capacity of the main catalyst and all other catalysts.

In particular, it is provided that the oxygen content of the exhaust gas flowing through the exhaust gas aftertreatment system, in particular the main catalytic converter, is kept so low during the unfired overrun phase that the oxygen content remains within the scope of the oxygen storage capacity of the exhaust gas aftertreatment components of the exhaust gas aftertreatment system, in particular within the scope of the oxygen storage capacity of the main catalytic converter .

It can thereby be possible that the efficiency of the main catalytic converter or the main catalytic converters, which act in particular as 3-way catalytic converters, is or are essentially unaffected within the overrun phase. In particular, the 3-way catalytic converter and possibly all other exhaust gas components, which act in particular as a 3-way catalytic converter, can be kept in the best possible condition for converting the pollutant components, so that the efficiency is kept at the highest possible level at all times. This makes it possible to improve the efficiency of the exhaust aftertreatment system compared to conventional gasoline engine configurations, even during transient processes, in order to come closer to the so-called vision of “zero impact emissions”. In particular, it is provided that at no time does the pollutant emission conversion level of the exhaust gas aftertreatment system fall below a pollutant emission conversion level threshold value, below which there is no longer a sufficiently high level of pollutant emission reduction.

If necessary, it is provided that the amount of oxygen in the exhaust gas flowing through the main catalytic converter in the unfired overrun phase is kept so low that the efficiency of the main catalytic converter, in particular the main catalytic converter acting as a 3-way catalytic converter, is unaffected, or that the in the unfired overrun phase, the amount of oxygen in the exhaust gas flowing through the main catalytic converter and at least one additional catalytic converter of the exhaust aftertreatment system is kept so low that the efficiency of the main catalytic converter, in particular the main catalytic converter acting as a 3-way catalytic converter, and the at least one additional catalytic converter is unaffected, so that in particular the overall efficiency of the exhaust aftertreatment system consisting of several elements is largely unaffected, or that the amount of oxygen in the exhaust gas flowing through the main catalytic converter and all other catalytic converters of the exhaust aftertreatment system in the unfired overrun phase is kept so low that the efficiency of the main catalytic converter, in particular the main catalytic converter acting as a 3-way catalytic converter, and all other catalytic converters is unaffected, so that the overall efficiency of the exhaust aftertreatment system, which consists of several elements, is largely unaffected.

If necessary, it is provided that the amount of oxygen in the exhaust gas in the unfired overrun phase in the main catalytic converter is kept so low that the efficiency of the main catalytic converter, in particular the main catalytic converter acting as a 3-way catalytic converter, is unaffected.

If necessary, provision is made for the amount of oxygen in the exhaust gas in the main catalytic converter and at least one further catalytic converter of the exhaust gas after-treatment system to be kept so low in the unfired overrun phase that the efficiency of the main catalytic converter, in particular the main catalytic converter acting as a 3-way catalytic converter, and of the at least one further catalyst is unaffected.

If necessary, it is provided that the amount of oxygen in the exhaust gas in the unfired overrun phase in the main catalytic converter and all other catalytic converters of the exhaust gas aftertreatment system is kept so low that the efficiency of the main catalytic converter, in particular the main catalytic converter acting as a 3-way catalytic converter, and all other catalysts is unaffected.

In particular, it is provided that the oxygen content of the exhaust gas flowing through the exhaust gas aftertreatment system, in particular the main catalytic converter, is kept so low during the unfired overrun phase that no active strategy for emptying the oxygen accumulator has to be followed in order to achieve sufficient efficiency, in particular a 3-way conversion capability make possible.

If necessary, it is provided that the amount of oxygen in the exhaust gas flowing through the main catalytic converter in the unfired overrun phase is kept so low that the rich operation of the Otto engine that takes place during the transition from the overrun phase to the normal operating phase impairs the mode of operation of the main catalytic converter, in particular the 3-way -Catalyst-acting main catalyst, is produced, or that the amount of oxygen in the exhaust gas flowing through the main catalyst and at least one further catalyst of the exhaust aftertreatment system in the unfired overrun phase is kept so low that the rich operation of the Otto engine that takes place during the transition from the overrun phase to the normal operating phase reduces the mode of operation of the main catalytic converter, in particular the main catalytic converter acting as a 3-way catalytic converter, and the at least one additional catalytic converter is produced, or that the amount of oxygen in the exhaust gas flowing through the main catalytic converter and all other catalytic converters of the exhaust aftertreatment system in the unfired overrun phase is kept so low that the the mode of operation of the main catalytic converter, in particular the main catalytic converter acting as a 3-way catalytic converter, and all other catalytic converters is established during the transition from the overrun phase to the normal operating phase.

If necessary, it is provided that the amount of oxygen in the exhaust gas in the unfired overrun phase in the main catalytic converter is kept so low that the operation of the main catalytic converter, in particular as a 3- WegKatalysator acting main catalyst is produced.

If necessary, it is provided that the amount of oxygen in the exhaust gas in the unfired overrun phase in the main catalytic converter and at least one other catalytic converter of the exhaust aftertreatment system is kept so low that the rich operation of the Otto engine that takes place during the transition from the overrun phase to the normal operating phase impairs the mode of operation of the main catalytic converter, in particular the main catalyst acting as a 3-way catalyst, and the at least one further catalyst is produced.

If necessary, it is provided that the amount of oxygen in the exhaust gas in the main catalytic converter and all other catalytic converters of the exhaust gas aftertreatment system in the unfired overrun phase is kept so low that the rich operation of the Otto engine that takes place during the transition from the overrun phase to the normal operating phase impairs the mode of operation of the main catalytic converter, in particular the main catalyst acting as a 3-way catalyst, and all other catalysts is produced.

In particular, it is provided that the oxygen content of the exhaust gas flowing through the exhaust gas aftertreatment system, in particular the main catalytic converter, is kept so low during the unfired overrun phase that a restart strategy with at least one short sub-stoichiometric combustion phase is sufficient to restore or increase the 3-way conversion capability . to ensure.

If necessary, it is provided that the air supply to the Otto engine is or is stopped during the transition to the unfired overrun phase, the air supply to the Otto engine being stopped in particular by closing a throttle valve upstream of the Otto engine.

By closing the throttle valve, the air supply to the Otto engine can be stopped. As a result, it may be possible to suck in the exhaust gas generated before or during the transition to the unfired overrun phase via the exhaust gas recirculation line during unfired overrun operation due to the movement of the cylinders. Through this suction, the exhaust gas generated before or during the transition to the unfired overrun phase during the unfired

Overrun phase are performed or pumped in a circle.

If necessary, it is provided that the exhaust gas recirculation line is or remains open during the transition to the unfired overrun phase, the exhaust gas recirculation line being opened in particular by opening an exhaust gas recirculation valve.

Through the exhaust gas recirculation line, the exhaust gas generated before or during the transition to the unfired overrun phase is fed to the Otto engine in the unfired overrun phase. It can be provided that the exhaust gas recirculation line is closed in the normal operating phase and in the fired overrun phase.

If necessary, it is provided that the gasoline engine in the unfired overrun phase is fed exclusively that exhaust gas via an exhaust gas recirculation line that was generated in the gasoline engine before or during the transition from the normal operating phase to the unfired overrun phase, or that the gasoline engine in the unfired overrun phase exclusively that exhaust gas is supplied via an exhaust gas recirculation line, which was generated before or during the transition from the fired overrun phase to the unfired overrun phase in the gasoline engine.

If necessary, it is provided that during the entire unfired overrun phase, the gasoline engine is fed via an exhaust gas recirculation line that exhaust gas which before or during the transition from the normal operating phase to the unfired overrun phase or before or during the transition from the fired overrun phase to the unfired overrun phase was generated in the gasoline engine.

If necessary, it is provided that the gas conveyed by the Otto engine in the unfired overrun phase has an oxygen content of less than 5% by volume or essentially zero, and/or that the amount of oxygen in the exhaust gas flowing through the Otto engine in the unfired overrun phase is smaller or equal to the oxygen storage capacity of the main catalytic converter, at least one further catalytic converter in the exhaust aftertreatment system and/or all catalytic converters in the exhaust aftertreatment system, and/or that the amount of oxygen in the exhaust gas flowing through the Otto engine in the unfired overrun phase is kept so low that the efficiency of the main catalytic converter, in particular of the main catalytic converter acting as a 3-way catalytic converter, at least one further catalytic converter of the exhaust after-treatment system and/or all catalytic converters of the exhaust after-treatment system is unaffected, and/or that the amount of oxygen in the exhaust gas flowing through the Otto engine in the unfired overrun phase is kept so low that the from the overrun phase to the normal operating phase of the rich operation of the Otto engine, the mode of operation of the main catalytic converter, in particular the main catalytic converter acting as a 3-way catalytic converter, at least one further catalytic converter in the exhaust gas after-treatment system and/or all catalytic converters in the exhaust gas after-treatment system is established.

If necessary, it is provided that the Otto engine arrangement comprises a high-pressure EGR system with a high-pressure EGR line, and that the exhaust gas supplied to the Otto engine in the unfired overrun phase is returned to the Otto engine through the high-pressure EGR line.

If necessary, the exhaust gas recirculation line is designed as a high-pressure EGR line.

Optionally, it is provided that the exhaust gas fed to the Otto engine exits the high-pressure EGR line before the Otto engine, and that the exhaust gas fed to the Otto engine enters the high-pressure AGR line between the Otto engine and a turbine of a turbocharger of the Otto engine.

[0067] This means that, if necessary, in the unfired overrun phase of the Otto engine, the exhaust gas generated before or during the transition to the unfired overrun phase is fed to the Otto engine via a high-pressure EGR line. As a result, the exhaust gas generated can enter the high-pressure EGR line between the gasoline engine and a turbine of the turbocharger and exit the high-pressure EGR line before the gasoline engine.

In this case, the exhaust gas generated can only flow through the Otto engine in unfired overrun mode. If necessary, it is provided that in the unfired overrun phase the essentially oxygen-free exhaust gas located in the exhaust aftertreatment system before or during the transition to the unfired overrun phase remains in the exhaust aftertreatment system, in particular in the main catalytic converter, even during the unfired overrun phase.

In the context of the present invention, the exhaust gas produced can be the exhaust gas produced before or during the transition to the unfired overrun phase, i.e. the low-oxygen, in particular essentially oxygen-free, produced in the normal operating phase or in the fired overrun phase by the combustion of fuel in the Otto engine. Exhaust gas to be understood.

Optionally, it is provided that the Otto engine arrangement comprises a bypass line, and that the exhaust gas supplied to the Otto engine in the unfired overrun phase is returned to the Otto engine through the bypass line.

If necessary, the exhaust gas recirculation line is designed as a bypass line.

If necessary, it is provided that the exhaust gas supplied to the gasoline engine exits the bypass line before the gasoline engine, with the exhaust gas supplied to the gasoline engine entering the bypass line between the gasoline engine and a turbine of a turbocharger of the gasoline engine, or with the dem Exhaust gas supplied to the Otto engine enters the bypass line between the main catalytic converter and a further catalytic converter, in particular an oxidation catalytic converter, or wherein the exhaust gas supplied to the Otto engine enters the bypass line between the main catalytic converter or an oxidation catalytic converter and a further catalytic converter of the exhaust gas aftertreatment system, or wherein the exhaust gas supplied to the petrol engine enters the bypass line after the last catalytic converter of the exhaust gas aftertreatment system.

In the unfired overrun phase, the exhaust gas generated before or during the transition to the unfired overrun phase can be fed via the bypass line to the Otto engine and then preferably to the exhaust gas aftertreatment system.

Depending on the embodiment, in the unfired overrun phase, the exhaust gas generated can enter the bypass line directly after the gasoline engine or after an exhaust gas aftertreatment component of the exhaust aftertreatment system. This can influence which components of the Otto engine arrangement, ie which exhaust gas aftertreatment components in addition to the Otto engine, are flowed through with the generated, essentially oxygen-free exhaust gas in the unfired overrun phase.

If necessary, it is provided that the Otto engine arrangement comprises a low-pressure EGR system with a low-pressure EGR line, and that the exhaust gas supplied to the Otto engine in the unfired overrun phase is returned to the Otto engine through the low-pressure EGR line.

If necessary, the exhaust gas recirculation line is designed as a low-pressure EGR line.

If necessary, it is provided that the exhaust gas supplied to the Otto engine exits the low-pressure EGR line before the Otto engine, the exhaust gas fed to the Otto engine entering the low-pressure EGR line between a turbine of a turbocharger of the Otto engine and the main catalytic converter, or wherein the exhaust gas fed to the Otto engine enters the low-pressure EGR line between the main catalytic converter and a further catalytic converter, in particular an oxidation catalytic converter, or wherein the exhaust gas fed to the Otto engine enters the low-pressure between the main catalytic converter or an oxidation catalytic converter and a further catalytic converter of the exhaust gas aftertreatment system -EGR line enters, or the exhaust gas supplied to the gasoline engine enters the low-pressure EGR line after the last catalytic converter of the exhaust gas aftertreatment system.

In the unfired overrun phase, the exhaust gas generated before or during the transition to the unfired overrun phase can be fed via the low-pressure EGR line to the Otto engine and then preferably to the exhaust gas aftertreatment system.

Depending on the embodiment, in the unfired overrun phase, the exhaust gas generated can enter the low-pressure EGR line directly after the gasoline engine or after an exhaust gas aftertreatment component of the exhaust aftertreatment system. This can influence which components of the Otto engine arrangement, ie which exhaust gas aftertreatment components in addition to the Otto engine, are flowed through with the generated exhaust gas in the unfired overrun phase.

Optionally, it is provided that the exhaust gas aftertreatment system comprises the main catalytic converter(s) and optionally one or more pre-catalysts and/or one or more secondary catalytic converters, in particular one or more oxidation catalytic converters, which comprise an oxidation catalytic converter coating , and/or one or more heated catalytic converter(s) and/or one or more gasoline engine particle filters coated in particular in gaseous form with effective exhaust gas aftertreatment and/or one or more NOx storage catalytic converter(s) and/or one or more exhaust gas aftertreatment component(s) which have a NOx Storage catalyst coating include, and / or one or more SCR system / s and / or one or more exhaust gas aftertreatment component / s, which include an SCR coating, and / or includes a secondary air injection or that the exhaust gas aftertreatment system from the / the main catalyst / s and optionally one or more primary catalyst(s) and/or one or more secondary catalyst(s), in particular one or more oxidation catalyst(s) which comprise(s) an oxidation catalyst coating, and/or one or more heated catalyst(s) and/or one or more, in particular one or more gaseous exhaust gas aftertreatment effective coated, Otto engine particle filter(s) and/or one or more NOx storage catalyst(s) and/or one or more exhaust gas aftertreatment component(s) which comprises a NOx storage catalyst coating(s) and/or one or more SCR system / s and / or one or more exhaust gas aftertreatment component / s, which comprises an SCR coating / s, and / or a secondary air injection is formed.

If necessary, it is provided that the exhaust gas generated in the normal operating phase or in the fired overrun phase by the combustion of fuel in the Otto engine first passes through the main catalytic converter, then the optionally provided oxidation catalytic converter, which comprises an oxidation catalytic converter coating, the optionally provided Otto engine particle filter, the optionally provided provided SCR catalyst and then flows through the optionally provided NOx storage catalyst.

If necessary, it is provided that the exhaust gas aftertreatment system comprises at least one main catalytic converter designed as a 3-way catalytic converter and/or acting as a 3-way catalytic converter, a gasoline engine particulate filter and/or a NOx storage catalytic converter, with the main catalytic converter possibly being located upstream of the gasoline engine particulate filter and the petrol engine particle filter is arranged in front of the NOx storage catalytic converter, or that the exhaust gas aftertreatment system is formed from at least one main catalytic converter designed as a 3-way catalytic converter and/or acting as a 3-way catalytic converter, from a petrol engine particle filter and/or from a NOx storage catalytic converter, Where appropriate, the main catalytic converter is arranged in front of the gasoline engine particle filter and the gasoline engine particle filter is arranged in front of the NOx storage catalytic converter.

If necessary, it is provided that the exhaust gas after-treatment system comprises at least one main catalytic converter and a gasoline engine particle filter arranged downstream of the main catalytic converter that can be regenerated using oxygen and/or nitrogen dioxide, that the exhaust gas after-treatment system comprises a supply line which opens into the exhaust gas after-treatment system and that in regeneration operation via a or oxygen and in particular air, preferably filtered ambient air, is fed to the supply line leading into the exhaust aftertreatment system upstream of the gasoline engine particle filter for regeneration of the gasoline engine particle filter, with the oxygen content of the exhaust gas flowing through the main catalytic converter or of the exhaust gas located in the main catalytic converter being less than 5% by volume in regeneration mode or is essentially zero, and/or wherein the amount of oxygen in the exhaust gas flowing through the main catalytic converter in the regeneration mode or the amount of oxygen in the exhaust gas located in the main catalytic converter is kept so low that the efficiency of the

Main catalyst is unaffected.

If necessary, it is provided that the exhaust gas after-treatment system comprises a NOx storage catalytic converter arranged downstream of the main catalytic converter and/or possibly the Otto engine particle filter, that the exhaust gas after-treatment system comprises a feed line that opens into the exhaust gas after-treatment system, that in storage operation of the NOx storage catalytic converter the NOx storage catalytic converter via the line that opens into the exhaust gas after-treatment system Oxygen and in particular air, preferably filtered and/or compressed ambient air, is supplied to the supply line, that an oxidation catalytic converter is optionally provided between the main catalytic converter and the NOx storage catalytic converter, and that the oxidation catalytic converter comprises an oxidation catalytic converter coating, the oxygen content of the exhaust gas flowing through the main catalytic converter or of the exhaust gas in the main catalytic converter is less than 5 vol of the main catalytic converter is unaffected.

If necessary, it is provided that the exhaust gas aftertreatment system comprises an SCR catalytic converter downstream of the main catalytic converter, the oxidation catalytic converter and/or the gasoline engine particle filter, that the SCR catalytic converter is optionally arranged upstream of the NOx storage catalytic converter, that in the reduction mode of the SCR catalytic converter the SCR - Catalyst for the reduction of the nitrogen oxides via a supply line or the supply line opening into the exhaust aftertreatment system, oxygen and in particular air, preferably ambient air, optionally filtered or compressed, is supplied, with the oxygen content of the exhaust gas flowing through the main catalytic converter being less than 5% by volume in reduction mode or in Is essentially zero, and/or wherein the amount of oxygen in the exhaust gas flowing through the main catalytic converter in the reduction mode is kept so low that the efficiency of the main catalytic converter is unaffected.

Optionally, it is provided that oxygen, in particular ambient air, is supplied to the gasoline engine particle filter, the oxidation catalytic converter, the NOx storage catalytic converter and/or the SCR catalytic converter and/or a further catalytic converter via a supply line.

Alternatively, it is provided that oxygen, in particular ambient air, is supplied to the gasoline engine particle filter, the oxidation catalytic converter, the NOx storage catalytic converter and/or the SCR catalytic converter and/or a further catalytic converter via a separate supply line.

If necessary, it is provided that a fuel, in particular so-called AdBlue®, is introduced into the exhaust gas aftertreatment system by a metering device upstream of the SCR catalytic converter, in particular downstream of the oxidation catalytic converter, with the fuel containing a reducing agent for nitrogen oxide reduction or in a reducing agent for nitrogen oxide reduction can be implemented, and/or that a reducing agent for reducing nitrogen oxides, in particular ammonia NHs, through the main catalytic converter, in particular through the 3-way catalytic converter, as part of normal gasoline engine operation and/or by possibly temporarily adjusting the gasoline engine operating parameters of the gasoline engine, in particular by the Petrol engine is operated sub-stoichiometrically generated.

In particular, the invention relates to a spark-ignition engine arrangement, the spark-ignition engine arrangement comprising a spark-ignition engine and an exhaust gas after-treatment system with at least one main catalytic converter, the spark-ignition engine being operable in an operating phase that includes a normal operating phase and an overrun phase, the spark-ignition engine being fuel and fuel in the normal operating phase converts air into an exhaust gas, with the Otto engine being operated and/or regulated in the normal operating phase preferably in a lambda window around A=1, with the overrun phase being formed by at least one unfired overrun phase and/or at least one fired overrun phase, and in the fired overrun phase, the gas flowing through the main catalytic converter is low in oxygen, in particular

which is essentially oxygen-free, and in particular the exhaust gas of a stoichiometric or sub-stoichiometric, in particular phase-wise sub-stoichiometric, combustion, characterized in that an exhaust gas recirculation line is provided, which the gasoline engine in an unfired overrun phase before or during the transition from the normal operating phase to the unfired Overrun phase supplies exhaust gas generated in the Otto engine, or that an exhaust gas recirculation line is provided which supplies the Otto engine in an unfired overrun phase with the exhaust gas produced before or during the transition from the fired overrun phase to the unfired overrun phase in the Otto engine.

If necessary, provision is made for the fuel supply to be stopped in the unfired overrun phase.

If necessary, it is provided that the overrun phase is formed by at least one unfired overrun phase and/or at least one fired overrun phase, and that the gas flowing through the main catalytic converter in the fired overrun phase is essentially oxygen-free and in particular the exhaust gas of a stoichiometric or substoichiometric combustion is.

If necessary, it is provided that in the normal operating phase air, in particular oxygen, can be fed to a NOx storage catalytic converter of the exhaust gas aftertreatment system via the exhaust gas recirculation line, whereby the NOx storage catalytic converter can be operated within its regular storage mode.

If necessary, it is provided that the Otto engine arrangement is set up to carry out the method according to the invention.

If necessary, it is provided that an oxidation catalytic converter coated with an oxidation catalytic converter coating is provided between the main catalytic converter and one or the spark-ignition engine particle filter, or that one or the spark-ignition engine particle filter is provided with an oxidation catalytic converter coating at least in its front region, the oxidation catalytic converter Coating is set up to convert NO with O2» to NO».

If necessary, it is provided that after the Otto engine and before the main catalytic converter, in particular in the front area of the main catalytic converter, a heating element, in particular catalytically coated, is provided for heating the main catalytic converter, and/or that after the Otto engine, in particular after the main catalytic converter, and upstream of the oxidation catalytic converter, in particular in the front area of the oxidation catalytic converter, a heating element, in particular catalytically coated, for heating the oxidation catalytic converter is provided, and/or that downstream of the gasoline engine, in particular downstream of the oxidation catalytic converter, and in front of the gasoline engine particulate filter, in particular in the front region of the gasoline engine particulate filter , a heating element, in particular a catalytically coated one, is provided for heating the gasoline engine particle filter, and/or that after the gasoline engine, in particular after the gasoline engine particle filter, and in front of a NOx storage catalytic converter, in particular in the front area of the NOx storage catalytic converter, a particularly catalytically coated, Heating element is provided for heating the NOx storage catalyst.

If necessary, it is provided that the Otto engine arrangement comprises a Otto engine and an exhaust gas after-treatment system with at least the main catalytic converter, the Otto engine particle filter and a NOx storage catalytic converter, that the main catalytic converter is designed or acts as a 3-way catalytic converter, that the main catalytic converter is connected to the Otto engine particle filter, which optionally acts as a 4-way catalytic converter, is arranged downstream, that the NOx storage catalytic converter is arranged downstream of the Otto engine particle filter, and that optionally one or the oxidation catalytic converter is arranged upstream of the NOx storage catalytic converter.

If necessary, it is provided that the NOx storage catalytic converter is the last catalytic converter of the exhaust gas aftertreatment system in the flow direction of the exhaust gas.

[0097] Further features according to the invention can be found in the claims, the description of the exemplary embodiments and the figures.

The invention will now be explained further using the example of exemplary, non-exclusive and/or non-limiting embodiments.

1 shows a schematic diagram of a first embodiment of a spark-ignition engine arrangement according to the invention,

2a, 2b and 2c show schematic diagrams of different variations of a second embodiment of a spark ignition engine arrangement according to the invention, and

Figures 3a, 3b and 3c show schematic diagrams of different variations of a third embodiment of a spark ignition engine arrangement according to the invention.

Unless otherwise indicated, the reference numbers correspond to the following components:

Gasoline engine 1, exhaust gas aftertreatment system 2, main catalytic converter 3, another exhaust gas aftertreatment component 4, turbocharger 5, throttle valve 6, compressor 7, turbine 8 and exhaust gas recirculation line 9.

The other / n exhaust gas aftertreatment component / s 4 may optionally include a 3-way catalyst and / or a 4-way catalyst and / or a NOx storage catalyst or from a 3-way catalyst and / or a 4-way Be formed catalyst and / or a NOx storage catalyst.

In particular, it is provided that the exhaust gas aftertreatment system 2 includes a main catalytic converter 3 and a 4-way catalytic converter.

In particular, it is provided that the exhaust gas aftertreatment system 2 includes a main catalytic converter 3, an oxidation catalytic converter and a 4-way catalytic converter.

In particular, it is provided that the exhaust gas aftertreatment system 2 includes a main catalytic converter 3, an oxidation catalytic converter, a 4-way catalytic converter and a NOx storage catalytic converter.

In particular, it is provided that the exhaust gas aftertreatment system 2 includes a main catalytic converter 3, a 4-way catalytic converter and a NOx storage catalytic converter.

1 shows a schematic graphic representation of a first embodiment of a spark-ignition engine arrangement according to the invention, which is suitable and/or set up for carrying out the method according to the invention.

In this embodiment, the Otto engine arrangement comprises a Otto engine 1 and an exhaust gas aftertreatment system 2. The exhaust gas aftertreatment system 2 includes a main catalytic converter 3 and an exhaust gas aftertreatment component 4 arranged downstream of the main catalytic converter 3. In this embodiment, the main catalytic converter 3 is designed as a 3-way catalytic converter and is installed directly in the Connection to the turbine 8 of the turbocharger 5, in particular close to the engine, arranged. The further exhaust gas aftertreatment component 4 is designed as a gasoline engine particle filter in one embodiment of the first embodiment of the gasoline engine assembly according to the invention and as a 4-way catalytic converter in another embodiment of the first embodiment of the gasoline engine assembly according to the invention.

The Otto engine arrangement also includes a turbocharger 5 and a throttle valve 6. The turbocharger 5 includes a compressor 7 and a turbine 8.

The Otto engine arrangement is operated in an operating phase, which includes a normal operating phase and an overrun phase. In the normal operating phase, fuel is supplied to the Otto engine 1 . In the normal operating phase, the fuel is converted with air to form an exhaust gas. In the normal operating phase, the Otto engine 1 is operated and/or regulated in a lambda window around A=1. This means that the Otto engine 1 oscillates around a lambda value X of 1.0 and is operated and/or regulated in the range from λ=0.9 to 1.1, preferably from λ=0.95 to 1.05. According to this embodiment it can be provided that the Otto

engine 1 is operated and/or regulated in its normal operating phase in phases or permanently rich or lean.

In the overrun phase, the Otto engine 1 is dragged by the mass in motion. The overrun phase includes at least one unfired and/or at least one fired overrun phase.

In the fired overrun phase, the fuel supply to the Otto engine 1 is only reduced and only that amount of fuel is introduced into the combustion chambers of the Otto engine 1 that is required to convert the amount of oxygen introduced by the air into a substantially oxygen-free exhaust gas. In particular, stoichiometric or sub-stoichiometric combustion takes place in the combustion chambers of the Otto engine 1 in the fired overrun phase.

The exhaust gas generated in the normal operating phase and in the fired overrun phase in the gasoline engine 1 first flows through the turbine 8 of the turbocharger 5, then the main catalytic converter 3 and then the other exhaust gas aftertreatment component 4 before it escapes into the environment.

In the unfired overrun phase, the fuel supply to the Otto engine 1 is interrupted. In contrast to conventional methods in which air is pumped through the Otto engine 1 in the unfired overrun phase, according to this embodiment the exhaust gas generated before or during the transition to the unfired overrun phase is pumped in a circuit. This means that the exhaust gas generated before or during the transition to the unfired overrun phase enters an exhaust gas recirculation line 9 after the gasoline engine 1 and exits the exhaust gas recirculation line 9 before the gasoline engine 1, in particular on the intake side. Furthermore, the essentially oxygen-free exhaust gas remains in the exhaust gas aftertreatment system 2, in particular in the main catalytic converter 3 and in the further exhaust gas aftertreatment component 4, during the unfired overrun phase.

The essentially oxygen-free exhaust gas was generated in the normal operating phase or in the fired overrun phase. In particular, the essentially oxygen-free exhaust gas generated before or during the transition to the unfired overrun phase is pumped in a circuit during the unfired overrun phase through the cylinders of the Otto engine 1 driven by the crankshaft.

As a result, the oxygen content of the exhaust gas in the exhaust gas aftertreatment system 2, in particular in the main catalytic converter 3, during the unfired overrun phase essentially corresponds to the oxygen content of the exhaust gas that flows through the exhaust gas aftertreatment system 2 in the normal operating phase or in the fired overrun phase. In contrast to conventional methods, the exhaust gas aftertreatment system 2 is not flowed through and/or flooded with oxygen-containing exhaust gas during the unfired overrun phase.

According to this embodiment, the exhaust gas recirculation line 9 is designed as a high-pressure EGR line of a high-pressure EGR system of the Otto engine arrangement.

During the transition to the unfired overrun phase, the air supply to the Otto engine 1 is stopped by the closing of the throttle valve 6 . Furthermore, the exhaust gas recirculation line 9 remains or is opened by opening the exhaust gas recirculation valve.

During the unfired overrun phase, only the exhaust gas generated before or during the transition to the unfired overrun phase is fed to the Otto engine 1 .

[00121] This makes it possible to resolve the conflict of objectives mentioned above and to create a method and an Otto engine arrangement which enables low fuel consumption and low pollutant emissions.

In other words, the introduction of air, the so-called air flooding, of the exhaust aftertreatment system 2 in the case of load gaps, which takes place in conventional methods

or thrust with negative consequences for the function of the exhaust gas purification and the thermomechanical stress on the exhaust gas aftertreatment system 2 can be avoided and/or reduced. Provision is preferably made for the throttle valve 6 to be completely closed or kept closed in the unfired overrun phase and for an exhaust gas recirculation line 9 connecting the intake and exhaust sides of the Otto engine 1 to be opened or kept open. Even with dynamic engine operation, comparatively hot engine exhaust gas remains in the circuit essentially without free oxygen. As a result, any storage of oxygen that may occur in the main catalytic converter 3 and the additional exhaust gas aftertreatment component 4 and the subsequently required rich operation of the Otto engine 1 as a result can be prevented. Furthermore, as a result, only small thermal gradients or no thermal gradients occur in the exhaust gas aftertreatment system 2 .

This means that according to the method for operating the Otto engine arrangement in the unfired overrun phase, exhaust gas that was generated before or during the transition from the normal operating phase to the unfired overrun phase in the Otto engine 1 is fed back to the Otto engine 1. The exhaust gas supplied to the Otto engine 1 in the unfired overrun phase was generated in the fired overrun phase or in the normal operating phase by burning the fuel with air and is essentially free of oxygen.

2a, 2b and 2c show schematic graphic representations of different variations of a second embodiment of a gasoline engine arrangement according to the invention, which is suitable and/or set up for carrying out the method according to the invention. The features of the embodiment according to FIGS. 2a, 2b and 2c can preferably correspond to the features of the embodiments according to FIG.

In contrast to the first embodiment, which is shown in FIG. 1, the exhaust gas recirculation line 9 is designed as a bypass line.

In FIG. 2a, the exhaust gas generated before or during the transition to the unfired overrun phase enters the bypass line after the gasoline engine 1 and exits the bypass line before the gasoline engine 1. In this embodiment, the essentially oxygen-free exhaust gas generated before or during the transition to the unfired overrun phase only flows through the Otto engine 1 and the bypass line during the unfired overrun phase.

In FIG. 2b, the exhaust gas generated before or during the transition to the unfired overrun phase enters the bypass line after the main catalytic converter 3 and exits the bypass line before the gasoline engine 1. In this embodiment, the essentially oxygen-free exhaust gas generated before or during the transition to the unfired overrun phase flows through the gasoline engine 1, the turbine 8 of the turbocharger 5, the main catalytic converter 3 and the bypass line during the unfired overrun phase.

In FIG. 2c, the exhaust gas generated before or during the transition to the unfired overrun phase enters the bypass line after the further main catalytic converter 3 and exits the bypass line before the gasoline engine 1. In this embodiment, the essentially oxygen-free exhaust gas generated before or during the transition to the unfired overrun phase flows through the gasoline engine 1, the turbine 8 of the turbocharger 5, the main catalytic converter 3 and the further exhaust gas aftertreatment component 4 and the bypass line during the unfired overrun phase.

In an embodiment that is not shown, the exhaust gas generated before or during the transition to the unfired overrun phase enters the bypass line after the last catalytic converter of the exhaust gas aftertreatment system 2 and exits the bypass line before the gasoline engine 1 . In this embodiment, the essentially oxygen-free exhaust gas generated before or during the transition to the unfired overrun phase flows through the gasoline engine 1, the turbine 8 of the turbocharger 5, all exhaust gas aftertreatment components 4 of the exhaust gas aftertreatment system 2 and the bypass line during the unfired overrun phase.

3a, 3b and 3c show schematic graphical representations of different variations of a third embodiment of a spark-ignition engine arrangement according to the invention, which

che is suitable and/or set up for carrying out the method according to the invention. The features of the embodiment according to FIGS. 3a, 3b and 3c can preferably correspond to the features of the embodiments according to FIG. 1, FIG. 2a, 2b and/or FIG. 2c.

In contrast to the first embodiment, which is shown in Fig. 1, the exhaust gas recirculation line 9 is designed as a low-pressure EGR line of a low-pressure EGR system of the Otto engine arrangement.

In Fig. 3a, the exhaust gas generated before or during the transition to the unfired overrun phase enters the low-pressure EGR line after the turbine 8 of the turbocharger 5 and exits the low-pressure EGR line before the gasoline engine 1. In this embodiment, the essentially oxygen-free exhaust gas generated before or during the transition to the unfired overrun phase flows through only the gasoline engine 1, the turbine 8 of the turbocharger 5 and the low-pressure EGR line during the unfired overrun phase.

In FIG. 3b, the exhaust gas generated before or during the transition to the unfired overrun phase occurs after the main catalytic converter 3 in the low-pressure EGR line and before the gasoline engine 1 from the low-pressure EGR line. In this embodiment, the essentially oxygen-free exhaust gas generated before or during the transition to the unfired overrun phase flows through the gasoline engine 1, the turbine 8 of the turbocharger 5, the main catalytic converter 3 and the low-pressure EGR line during the unfired overrun phase.

In FIG. 3c, the exhaust gas generated before or during the transition to the unfired overrun phase enters the low-pressure EGR line after the further exhaust gas aftertreatment component 4 and exits the low-pressure EGR line before the gasoline engine 1. In this embodiment, the essentially oxygen-free exhaust gas generated before or during the transition to the unfired overrun phase during the unfired overrun phase flows through the Otto engine 1, the turbine 8 of the turbocharger 5, the main catalytic converter 3, the further exhaust gas aftertreatment component 4 and the low-pressure EGR Management.

In an embodiment that is not shown, the exhaust gas generated before or during the transition to the unfired overrun phase enters the low-pressure EGR line after the last exhaust gas aftertreatment component 4 of the exhaust aftertreatment system 2 and exits the low-pressure EGR line before the gasoline engine 1 . In this embodiment, the essentially oxygen-free exhaust gas generated before or during the transition to the unfired overrun phase flows through the gasoline engine 1, the turbine 8 of the turbocharger 5, all exhaust gas aftertreatment components 4 of the exhaust gas aftertreatment system 2 and the low-pressure EGR line during the unfired overrun phase.

The invention is not limited to the illustrated embodiments, but includes any method and any Otto engine arrangement according to the following claims.

Claims (1)

patent claims 1. A method for operating a spark-ignition engine arrangement in an operating phase that includes a normal operating phase and an overrun operating phase, - wherein the Otto engine arrangement comprises a Otto engine (1) and an exhaust gas after-treatment system (2) with at least one main catalytic converter (3), - wherein in the normal operating phase in the Otto engine (1) fuel and air are converted into an exhaust gas, - wherein the Otto engine (1) is preferably operated and/or regulated in a lambda window around A=1 in the normal operating phase, - wherein the overrun phase is formed by at least one unfired overrun phase and/or at least one fired overrun phase, and wherein in the fired overrun phase the gas flowing through the main catalytic converter (3) is low in oxygen, in particular essentially free of oxygen, and in particular the exhaust gas is a stoichiometric or substoichiometric, in particular phased substoichiometric, combustion, wherein - in the unfired overrun phase, the gasoline engine (1) is fed via an exhaust gas recirculation line (9) with that exhaust gas which was produced in the gasoline engine (1) before or during the transition from the normal operating phase to the unfired overrun phase, - or the Otto engine (1) in the unfired overrun phase is supplied via an exhaust gas recirculation line (9) with that exhaust gas which was produced in the Otto engine (1) before or during the transition from a fired overrun phase to the unfired overrun phase, characterized in that - that the amount of oxygen in the exhaust gas flowing through the main catalytic converter (3) and all other catalytic converters of the exhaust aftertreatment system (2) in the unfired overrun phase is less than or equal to the oxygen storage capacity of the main catalytic converter (3) and all other catalytic converters. 2. The method according to claim 1, characterized in that the fuel supply is or is stopped in the unfired overrun phase. 3. The method according to claim 1 or 2, characterized in that - in the normal operating phase and/or in the fired overrun phase, the exhaust gas of the Otto engine (1) is supplied to the main catalytic converter (3), - and that the main catalytic converter (3) as a 3- Way catalyst is formed or acts. 4. The method according to any one of the preceding claims, characterized in that the oxygen content of the exhaust gas located in the exhaust gas aftertreatment system (2) or that the oxygen content of the exhaust gas flowing through the exhaust gas aftertreatment system (2) in the overrun phase, in particular in the unfired overrun phase, essentially corresponds to the oxygen content of the exhaust gas flowing through the exhaust aftertreatment system (2) in the normal operating phase or in the fired overrun phase. 5. The method according to any one of the preceding claims, characterized in that the oxygen content of the exhaust gas located in the main catalytic converter (3) or that the oxygen content of the exhaust gas flowing through the main catalytic converter (3) in the unfired overrun phase essentially corresponds to the oxygen content of the gas flowing through the main catalytic converter (3). exhaust gas in the normal operating phase or in the fired overrun phase. 6. The method according to any one of the preceding claims, characterized in that - that the oxygen content of the exhaust gas located in the main catalytic converter (3) or the oxygen content of the exhaust gas flowing through the main catalytic converter (3) in the normal operating phase and/or in the overrun phase, in particular in the unfired overrun phase, is less than 5% by volume or essentially zero is, - Or that the oxygen content of the main catalyst (3) and at least one other catalyst of the exhaust gas aftertreatment system (2) located exhaust gas or The oxygen content of the exhaust gas flowing through the main catalytic converter (3) and at least one further catalytic converter of the exhaust gas aftertreatment system (2) is less than 5% by volume or essentially zero in the normal operating phase and/or in the overrun phase, in particular in the unfired overrun phase, - or that the oxygen content of the exhaust gas in the main catalytic converter (3) and in all other catalytic converters or the oxygen content of the exhaust gas flowing through the main catalytic converter (3) and all other catalytic converters of the exhaust gas aftertreatment system (2) in the normal operating phase and/or in the overrun phase, in particular in the unfired deceleration phase, is less than 5% by volume or essentially zero. 7. The method according to any one of the preceding claims, characterized in that - that the amount of oxygen in the exhaust gas flowing through the main catalytic converter (3) in the unfired overrun phase is kept so low that the efficiency of the main catalytic converter (3), in particular the main catalytic converter (3) acting as a 3-way catalytic converter, is unaffected, - or that the amount of oxygen in the exhaust gas flowing through the main catalytic converter (3) and at least one further catalytic converter of the exhaust gas after-treatment system (2) in the unfired overrun phase is kept so low that the efficiency of the main catalytic converter (3), in particular that which acts as a 3-way catalytic converter main catalytic converter (3) and the at least one further catalytic converter is unaffected, so that in particular the overall efficiency of the exhaust gas aftertreatment system (2), which consists of several elements, is largely unaffected, - or that the amount of oxygen in the exhaust gas flowing through the main catalytic converter (3) and all other catalytic converters of the exhaust gas after-treatment system (2) in the unfired overrun phase is kept so low that the efficiency of the main catalytic converter (3), in particular the main catalytic converter acting as a 3-way catalytic converter (3) and all other catalytic converters is unaffected, so that in particular the overall efficiency of the exhaust gas aftertreatment system (2), which consists of several elements, is largely unaffected. 8. The method according to any one of the preceding claims, characterized in that - that the amount of oxygen in the exhaust gas flowing through the main catalytic converter (3) in the unfired overrun phase is kept so low that the rich operation of the Otto engine (1) that occurs during the transition from the overrun phase to the normal operating phase impairs the mode of operation of the main catalytic converter (3), in particular the 3-way catalyst acting main catalyst (3), is produced, - or that the amount of oxygen in the exhaust gas flowing through the main catalytic converter (3) and at least one further catalytic converter of the exhaust gas aftertreatment system (2) in the unfired overrun phase is kept so low that the rich operation of the Otto engine (1) that takes place during the transition from the overrun phase to the normal operating phase the mode of action of the main catalytic converter (3), in particular the main catalytic converter (3) acting as a 3-way catalytic converter, and the at least one further catalytic converter is produced, - or that the amount of oxygen in the exhaust gas flowing through the main catalytic converter (3) and all other catalytic converters of the exhaust gas aftertreatment system (2) in the unfired overrun phase is kept so low that the rich operation of the Otto engine (1) that takes place during the transition from the overrun phase to the normal operating phase Mode of operation of the main catalyst (3), in particular the main catalyst (3) acting as a 3-way catalyst, and all other catalysts is produced. 9. The method according to any one of the preceding claims, characterized in that the air supply to the Otto engine (1) is or is stopped during the transition to the unfired overrun phase, - the air supply to the Otto engine (1) being stopped in particular by closing one of the Otto engine (1) upstream throttle valve (6). 10 11. 12. 13. 14 15 Austrian AT 521 758 B1 2023-07-15 Method according to one of the preceding claims, characterized in that - that the exhaust gas recirculation line (9) is or remains open during the transition to the unfired overrun phase, _ - The exhaust gas recirculation line (9) being opened in particular by opening an exhaust gas recirculation valve. Method according to one of the preceding claims, characterized in that - That the Otto engine (1) in the unfired overrun phase is supplied exclusively to that exhaust gas via an exhaust gas recirculation line (9) that was generated in the Otto engine (1) before or during the transition from the normal operating phase to the unfired overrun phase, - or that the Otto engine (1) in the unfired overrun phase is supplied exclusively with that exhaust gas via an exhaust gas recirculation line (9) which was generated in the Otto engine (1) before or during the transition from the fired overrun phase to the unfired overrun phase. Method according to one of the preceding claims, characterized in that throughout the unfired overrun phase, the Otto engine (1) is supplied via an exhaust gas recirculation line (9) with that exhaust gas which before or during the transition from the normal operating phase to the unfired overrun phase or before or during the transition from the fired overrun phase to the unfired overrun phase in the Otto engine (1). Method according to one of the preceding claims, characterized in that - that the gas conveyed by the Otto engine (1) in the unfired overrun phase has an oxygen content of less than 5% by volume or essentially zero, - and/or that the amount of oxygen in the exhaust gas flowing through the Otto engine (1) in the unfired overrun phase is less than or equal to the oxygen storage capacity of the main catalytic converter (3), at least one additional catalytic converter in the exhaust aftertreatment system (2) and/or all catalytic converters in the exhaust aftertreatment system (2). , - and/or that the amount of oxygen in the exhaust gas flowing through the Otto engine (1) in the unfired overrun phase is kept so low that the efficiency of the main catalytic converter (3), in particular the main catalytic converter (3) acting as a 3-way catalytic converter, is at least one further catalytic converter of the exhaust aftertreatment system (2) and/or all catalytic converters (3) of the exhaust aftertreatment system (2) is unaffected, - and/or that the amount of oxygen in the exhaust gas flowing through the Otto engine (1) in the unfired overrun phase is kept so low that the rich operation of the Otto engine (1) that takes place during the transition from the overrun phase to the normal operating phase affects the mode of operation of the main catalytic converter (3), in particular the main catalytic converter (3) acting as a 3-way catalytic converter, at least one further catalytic converter of the exhaust gas aftertreatment system (2) and/or all catalytic converters (3) of the exhaust gas aftertreatment system (2). Method according to one of the preceding claims, characterized in that - that the Otto engine arrangement comprises a high-pressure EGR system with a high-pressure EGR line, - and that the exhaust gas supplied to the Otto engine (1) in the unfired overrun phase is returned to the Otto engine (1) through the high-pressure EGR line. Method according to claim 14, characterized in that - that the exhaust gas supplied to the petrol engine (1) exits the high-pressure EGR line before the petrol engine (1), - and that the exhaust gas supplied to the Otto engine (1) enters the high-pressure EGR line between the Otto engine (1) and a turbine (8) of a turbocharger (5) of the Otto engine (1). 16 17 18 19 20 Austrian AT 521 758 B1 2023-07-15 Method according to one of the preceding claims, characterized in that - That the Otto engine assembly includes a bypass line, - and that the exhaust gas supplied to the Otto engine (1) in the unfired overrun phase is returned to the Otto engine (1) through the bypass line. Method according to claim 16, characterized in that - that the exhaust gas supplied to the petrol engine (1) exits the bypass line before the petrol engine (1), - the exhaust gas supplied to the Otto engine (1) entering the bypass line between the Otto engine (1) and a turbine (8) of a turbocharger (5) of the Otto engine (1), - or wherein the exhaust gas supplied to the Otto engine (1) enters the bypass line between the main catalytic converter (3) and a further catalytic converter, in particular an oxidation catalytic converter, - or wherein the exhaust gas supplied to the Otto engine (1) enters the bypass line between the main catalytic converter or an oxidation catalytic converter and a further catalytic converter of the exhaust gas after-treatment system (2), - or wherein the exhaust gas supplied to the Otto engine (1) enters the bypass line after the last catalytic converter (3) of the exhaust gas aftertreatment system (2). Method according to one of the preceding claims, characterized in that - that the Otto engine assembly includes a low-pressure EGR system with a low-pressure EGR line, - and that the exhaust gas supplied to the Otto engine (1) in the unfired overrun phase is returned to the Otto engine (1) through the low-pressure EGR line. Method according to claim 18, characterized in that - that the exhaust gas supplied to the petrol engine (1) exits the low-pressure EGR line before the petrol engine (1), - the exhaust gas supplied to the Otto engine (1) entering the low-pressure EGR line between a turbine (8) of a turbocharger (5) of the Otto engine (1) and the main catalytic converter (3), - or wherein the exhaust gas supplied to the Otto engine (1) enters the low-pressure EGR line between the main catalytic converter (3) and a further catalytic converter, in particular an oxidation catalytic converter, - or wherein the exhaust gas supplied to the Otto engine (1) enters the low-pressure EGR line between the main catalytic converter or an oxidation catalytic converter and a further catalytic converter of the exhaust gas after-treatment system (2), - or wherein the exhaust gas supplied to the Otto engine (1) enters the low-pressure EGR line after the last catalytic converter (3) of the exhaust gas aftertreatment system (2). Method according to one of the preceding claims, characterized in that - That the exhaust gas treatment system (2) the / the main catalyst / s (3) and optionally one or more pre-catalyst / s and / or one or more secondary catalyst / s, in particular one or more oxidation catalyst / s, which / r includes an oxidation catalyst coating /en, and/or one or more heated catalytic converter(s) and/or one or more petrol engine particle filters, in particular coated in gaseous form with effective exhaust gas aftertreatment, and/or one or more NOx storage catalytic converter(s) and/or one or more exhaust gas aftertreatment component(s) (4) , which include a NOx storage catalytic converter coating, and/or one or more SCR system(s) and/or one or more exhaust gas aftertreatment component(s) (4), which include an SCR coating, and/or a secondary air injection system, - or that the exhaust gas aftertreatment system (2) consists of the main catalytic converter(s) (3) and optionally one or more primary catalytic converter(s) and/or one or more secondary catalytic converter(s), in particular one or more oxidation catalytic converter(s), which Coating comprises / s, and / or one or more heated catalyst / s and / or one or more, in particular one 21 22 23 Austrian AT 521 758 B1 2023-07-15 or more gaseous exhaust gas aftertreatment effective coated gasoline engine particulate filter(s) and/or one or more NOx storage catalytic converter(s) and/or one or more exhaust gas aftertreatment component(s) (4) which comprises a NOx storage catalytic converter coating/s, and/or one or more SCR system / s and / or one or more exhaust gas aftertreatment component / s (4), which comprises an SCR coating / s, and / or a secondary air injection is formed. Method according to one of the preceding claims, characterized in that - that the exhaust gas aftertreatment system (2) comprises at least one main catalytic converter (3) and a gasoline engine particle filter arranged downstream of the main catalytic converter (3) that can be regenerated using oxygen and/or nitrogen dioxide, - that the exhaust gas after-treatment system (2) comprises a feed line which opens into the exhaust gas after-treatment system (2), - that in a regeneration mode, oxygen and in particular air, preferably filtered ambient air, is supplied to regenerate the gasoline engine particle filter via the supply line that opens into the exhaust gas aftertreatment system (2) upstream of the gasoline engine particle filter, - wherein the oxygen content of the exhaust gas flowing through the main catalytic converter (3) or of the exhaust gas located in the main catalytic converter (3) in regeneration operation is less than 5% by volume or is essentially zero, - and/or wherein the amount of oxygen in the exhaust gas flowing through the main catalytic converter (3) in regeneration mode or the amount of oxygen in the exhaust gas in the main catalytic converter (3) is kept so low that the efficiency of the main catalytic converter (3) is unaffected. Method according to one of the preceding claims, characterized in that - that the exhaust aftertreatment system (2) comprises a NOx storage catalytic converter arranged downstream of the main catalytic converter (3) and/or possibly the Otto engine particle filter, - that the exhaust gas after-treatment system (2) comprises a feed line which opens into the exhaust gas after-treatment system (2), - that in the storage mode of the NOx storage catalytic converter, oxygen and in particular air, preferably filtered and/or compressed ambient air, is supplied to the NOx storage catalytic converter via the supply line which opens into the exhaust gas aftertreatment system (2), - that optionally an oxidation catalytic converter is provided between the main catalytic converter (3) and the NOx storage catalytic converter, and that the oxidation catalytic converter comprises an oxidation catalytic converter coating, - wherein the oxygen content of the exhaust gas flowing through the main catalytic converter (3) or of the exhaust gas located in the main catalytic converter (3) is less than 5% by volume or essentially zero in storage mode, - and/or the amount of oxygen in the exhaust gas flowing through the main catalytic converter (3) in storage mode or the amount of oxygen in the exhaust gas in the main catalytic converter (3) is kept so low that the efficiency of the main catalytic converter (3) is unaffected. Method according to one of the preceding claims, characterized in that - that the exhaust aftertreatment system (2) comprises an SCR catalytic converter downstream of the main catalytic converter (3), the oxidation catalytic converter and/or the gasoline engine particle filter, - that the SCR catalytic converter is optionally arranged in front of the NOx storage catalytic converter, - that the exhaust gas after-treatment system (2) comprises a feed line which opens into the exhaust gas after-treatment system (2), - that in the reduction mode of the SCR catalytic converter the SCR catalytic converter for the reduction of nitrogen oxides via the supply line opening into the exhaust gas aftertreatment system (2) oxygen and in particular air, preferably ambient air, if necessary 24 25 26 27 28 Austrian AT 521 758 B1 2023-07-15 filtered or compressed, is supplied, - wherein the oxygen content of the exhaust gas flowing through the main catalytic converter (3) in reduction mode is less than 5% by volume or essentially zero, - and/or wherein the amount of oxygen in the exhaust gas flowing through the main catalytic converter (3) in the reduction mode is kept so low that the efficiency of the main catalytic converter (3) is unaffected. Method according to one of the preceding claims, characterized in that - that a fuel, in particular so-called AdBlue®, is introduced into the exhaust aftertreatment system (2) by a metering device upstream of the SCR catalytic converter, in particular downstream of the oxidation catalytic converter, - where the fuel contains a reducing agent for reducing nitrogen oxides or can be converted into a reducing agent for reducing nitrogen oxides, - and/or that a reducing agent for reducing nitrogen oxides, in particular ammonia NHs3, through the main catalytic converter (3), in particular through the 3-way catalytic converter, as part of normal Otto engine operation and/or by possibly temporarily adjusting the Otto engine operating parameters of the Otto engine (1), in particular by operating the Otto engine (1) sub-stoichiometrically. gasoline engine arrangement, - wherein the Otto engine arrangement comprises a Otto engine (1) and an exhaust gas after-treatment system (2) with at least one main catalytic converter (3), - wherein the Otto engine (1) can be operated in an operating phase that includes a normal operating phase and an overrun phase, - wherein the gasoline engine (1) converts fuel and air into an exhaust gas in the normal operating phase, - wherein the gasoline engine (1) is preferably operated and/or controlled in a lambda window around A=1 in the normal operating phase, - wherein the overrun phase is formed by at least one unfired overrun phase and/or at least one fired overrun phase, - And wherein in the fired overrun phase the gas flowing through the main catalytic converter (3) is low in oxygen, in particular essentially free of oxygen, and in particular the exhaust gas is a stoichiometric or substoichiometric, in particular phased substoichiometric, combustion, wherein - an exhaust gas recirculation line (9) is provided, which supplies the Otto engine (1) in an unfired overrun phase with the exhaust gas generated before or during the transition from the normal operating phase to the unfired overrun phase in the Otto engine (1), - or an exhaust gas recirculation line (9) is provided, which supplies the Otto engine (1) with the exhaust gas produced before or during the transition from the fired overrun phase to the unfired overrun phase in the Otto engine (1) in an unfired overrun phase, - characterized in that the Otto engine arrangement for carrying out the method according to any one of claims 1 to 24 is set up. Otto engine arrangement according to Claim 25, characterized in that the fuel supply is stopped in the unfired overrun phase. Otto engine arrangement according to Claim 25 or 26, characterized in that - that the overrun phase is formed by at least one unfired overrun phase and/or at least one fired overrun phase, - And that in the fired overrun phase, the gas flowing through the main catalytic converter (3) is essentially free of oxygen and, in particular, is the exhaust gas of a stoichiometric or substoichiometric combustion. Gasoline engine arrangement according to one of claims 25 to 27, characterized in that in the normal operating phase a NOx storage catalyst of the exhaust gas aftertreatment system (2) air, in particular oxygen, via the exhaust gas recirculation line (9) can be supplied, whereby the NOx storage catalyst can be operated within its regular storage operation is cash. 29. Otto engine arrangement according to one of claims 25 to 28, characterized in that - that an oxidation catalyst coated with an oxidation catalyst coating is provided between the main catalyst (3) and one or the gasoline engine particle filter, - or that one or the gasoline engine particle filter is provided with an oxidation catalyst coating at least in its front area, - wherein the oxidation catalytic converter coating is set up to convert NO with O» to NO». 30. Otto engine arrangement according to one of claims 25 to 29, characterized in that - that after the Otto engine (1) and before the main catalytic converter (3), in particular in the front area of the main catalytic converter (3), a heating element, in particular catalytically coated, is provided for heating the main catalytic converter (3), - and/or that after the Otto engine (1), in particular after the main catalytic converter (3), and before the oxidation catalytic converter, in particular in the front area of the oxidation catalytic converter, a heating element, in particular catalytically coated, is provided for heating the oxidation catalytic converter, - and/or that after the Otto engine (1), in particular after the oxidation catalytic converter, and in front of the Otto engine particle filter, in particular in the front area of the Otto engine particle filter, a heating element, in particular catalytically coated, is provided for heating the Otto engine particle filter, - and/or that after the petrol engine (1), in particular after the petrol engine particle filter, and in front of a NOx storage catalytic converter, in particular in the front area of the NOx storage catalytic converter, a heating element, in particular catalytically coated, is provided for heating the NOx storage catalytic converter. 31. Otto engine arrangement according to one of claims 25 to 30, characterized in that - That the Otto engine arrangement comprises a Otto engine (1) and an exhaust gas after-treatment system (2) with at least the main catalytic converter (3), the Otto engine particle filter and a NOx storage catalytic converter, - that the main catalytic converter (3) is designed or acts as a 3-way catalytic converter, - that the main catalytic converter (3) is followed by the gasoline engine particle filter, which may act as a 4-way catalytic converter, - that the NOx storage catalytic converter is located downstream of the gasoline engine particle filter, - And that optionally one or the oxidation catalytic converter is arranged in front of the NOx storage catalytic converter. 32. Otto engine arrangement according to one of claims 25 to 31, characterized in that the NOx storage catalytic converter is the last catalytic converter of the exhaust gas aftertreatment system (2) in the flow direction of the exhaust gas. 7 sheets of drawings