WO2020069548A1 - Method and spark ignition engine arrangement having improved scr system - Google Patents

Abstract

The invention relates to a method for operating a spark ignition engine arrangement and to a spark ignition engine arrangement, the spark ignition arrangement comprising a spark ignition engine (1) and an exhaust gas aftertreatment system (2), the exhaust gas aftertreatment system (2) comprising a main catalytic converter (3) and an SCR catalytic converter (15) arranged downstream of the main catalytic converter (3), and, in a normal operating phase, fuel and air being converted into an exhaust gas in the spark ignition engine (1), wherein oxygen and in particular air are fed to the SCR catalytic converter (15) via a feed line (14) leading into the exhaust gas aftertreatment system (2) during a reduction operation of the SCR catalytic converter (15) for reduction of the nitrogen oxides, the oxygen content of the exhaust gas flowing through the main catalytic converter (3) during the reduction operation being less than 5 vol. % or substantially zero, and/or the oxygen volume of the exhaust gas flowing through the main catalytic converter (3) during the reduction operation being kept so low that the efficiency of the main catalytic converter (3) remains unaffected.

Description

 Method and gasoline engine arrangement with an improved SCR system

The invention relates to a method and a gasoline engine arrangement according to the

Preambles of the independent claims.

Different methods for operating an internal combustion engine are known from the prior art.

For example, methods are known in which the nitrogen oxides emitted by a diesel engine are selectively reduced on or in an SCR catalytic converter. Such SCR catalysts can be formed from titanium dioxide, vanadium pentoxide, tungsten dioxide, zeolites, in particular copper and iron zeolites, or activated carbon.

The superstoichiometric normal operation of the diesel engine requires this lean exhaust gas aftertreatment, the function of which is given in the exhaust gas temperature ranges that are typical for the diesel engine compared to the gasoline engine. As a rule, it is provided that the SCR catalytic converter does what is necessary for the reactions

Reducing agent, in particular ammonia NH3, is fed via a metering device.

The reducing agent can optionally be stored and / or stored at least temporarily in the SCR catalytic converter. The ammonia may accumulate at the active centers of the SCR catalytic converter. The at least temporarily stored reducing agent, in particular the ammonia NH3, can subsequently reduce nitrogen oxides NOx, such as in particular nitrogen monoxide NO and nitrogen dioxide NO2.

However, the lack of oxygen in combination with the high level, which is caused by the stoichiometric normal operation of the gasoline engine, has not proven to be advantageous for this reaction according to the prior art in the gasoline engine context

Exhaust gas temperature level.

Furthermore, methods for operating a diesel or gasoline engine are known, in which the particle-laden exhaust gas penetrates a porous filter wall Exhaust filter is filtered. During the filtration process, particles are retained by the filter medium of the exhaust gas filter and are deposited on it.

The filter walls of the exhaust gas filter can consist of different porous materials and can be constructed from fibers or powder, for example. The fibers or the powder itself consist in particular of ceramics or of metals. Classic ceramics are mullite, cordierite, silicon carbide (SiC) and aluminum titanate.

Due to the deposition of the particles on the surface or inside the filter wall, a particle layer influencing the filtration is formed - a so-called

Filter cake - off, which on the one hand leads to a further improvement in the filtration efficiency, which is preferably the best possible without any loading, on the other hand, the flow resistance and thus also the differential pressure at the exhaust gas filter generated by the exhaust gas volume flow increases.

Also in the gasoline engine arrangement, as is already the case with conventional ones

Diesel arrangements are known to regenerate the exhaust gas filter at a

Correspondingly high soot loading is required to prevent excessive back pressure or undesired temperature peaks that could damage the component if the soot burns up

To be able to reduce or prevent particle filters. Since a gasoline engine arrangement has a significantly lower particle raw emission level (particle mass) in combination with a significantly higher exhaust gas temperature level, regeneration is less necessary in the gasoline engine arrangement.

The use of synergies between a gasoline engine and a diesel engine is described below. In contrast to a diesel engine, in a gasoline engine there is no NO2 as a regeneration agent in the particle filter (here gasoline particle filter). Although the usual terminology for a diesel engine with a regeneration

Oxygen active regeneration and regeneration with N02 as passive

Denoted regeneration, the terms are used in the context of the invention, that is to say for a gasoline engine, as follows: Every regeneration with oxygen is referred to as active regeneration in the context of the invention, even if an active engine intervention to reduce soot particles is not necessarily provided. Subsequently a regeneration with NO2 is also referred to as a passive regeneration in the ottomotor context.

In conventional gasoline engine arrangements is compared to conventional

Diesel arrangements on the one hand the exhaust gas temperature higher, whereby a thermal oxidative regeneration, a so-called active regeneration, the

Gasoline engine particle filter, i.e. an oxidation of the carbon by the introduction of oxygen, is easier. On the other hand, compared to conventional diesel arrangements in conventional gasoline engine arrangements, the

stoichiometric normal operation less oxygen, which means significantly less

Oxygen is available for active regeneration of the gasoline engine particulate filter.

The object of the invention is to overcome the disadvantages of the prior art. In particular, it is an object of the invention to provide a method for operating a

To create a gasoline engine arrangement and such a gasoline engine arrangement in order to further maximize the already low nitrogen oxide level after the at least one main catalytic converter, in particular the 3-way catalytic converter, in particular in the direction of

Immission ambient air limit values to reduce or reduce. Furthermore, it is an object of the invention to store or implement by-product and intermediate product of catalytic reactions, such as, for example, NH3 which may be formed, in the catalysts. In particular, it is an object of the invention to overcome the disadvantages of

To overcome the state of the art. It is therefore an object of the invention

to come closer to the so-called vision of "Zero Impact Emission" in order to provide the end customer with a gasoline engine arrangement that is economical in terms of fuel consumption and to protect the environment as much as possible by falling below the pollutant emission laws prescribed by law.

The object of the invention is particularly characterized by the features of

independent claims solved.

The invention relates to a method for operating a gasoline engine arrangement, the gasoline engine arrangement comprising a gasoline engine and a gasoline engine

Exhaust gas aftertreatment system comprises, the exhaust gas aftertreatment system comprises at least one main catalytic converter and an SCR catalytic converter arranged downstream of the main catalytic converter, fuel and air being converted into exhaust gas in a normal operating phase in the gasoline engine.

According to the invention, it is provided that in the reduction mode of the SCR catalytic converter, the SCR catalytic converter is used to reduce the nitrogen oxides via a

Exhaust gas aftertreatment system feeding supply line oxygen and in particular air, preferably ambient air, optionally filtered or compressed, is supplied, the oxygen content of the exhaust gas flowing through the main catalyst in the reduction mode less than 5 vol .-% or

Is substantially zero, and / or wherein in the reduction mode

Main amount of oxygen flowing through the main catalyst of the exhaust gas is kept so low that the efficiency of the main catalyst is largely unaffected.

The gasoline engine arrangement can be the gasoline engine arrangement

Internal combustion engine, in particular the gasoline engine arrangement

Motor vehicle.

The SCR catalytic converter may be at a position in the

Exhaust aftertreatment system positioned in which the exhaust gas temperature when entering the SCR catalytic converter is lower than when it exits the gasoline engine.

In particular, the SCR catalytic converter is arranged downstream of the main catalytic converter (designed as a 3-way catalytic converter) and a gasoline engine particle filter and upstream of a NOx storage catalytic converter. It is favorable if the NOx storage catalytic converter is the last element of the exhaust gas aftertreatment system.

An oxidation catalytic converter can additionally be provided between the main catalytic converter and the gasoline engine particle filter, it being possible for this to be designed as part of the gasoline particle filter.

Furthermore, the exhaust gas aftertreatment system can include the main catalytic converter (s) and the SCR catalytic converter and optionally one or more precatalyst (s) and / or one or more secondary catalysts, in particular one or more oxidation catalysts, which have an oxidation catalyst coating

comprises / s, and / or one or more heating catalytic converter (s) and / or one or more gasoline particle filters / / and / or one or more NOx storage catalytic converter (s) and / or one or more exhaust gas aftertreatment component (s), in particular coated / gaseously effective with exhaust gas aftertreatment , which comprise a NOx storage catalytic converter coating, and / or comprise one or more SCR systems and / or one or more exhaust gas aftertreatment component / s, which comprise 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 the SCR catalytic converter 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 comprises an oxidation catalytic converter coating / s, and / or one or more heating catalyst (s) and / or one, in particular one or more gaseous exhaust gas aftertreatment, gasoline engine particle filter / s and / or one or more NOx storage catalyst (s) and / or one or more

 Exhaust aftertreatment component (s), which comprises a NOx storage catalytic converter coating, and / or one or more SCR system (s) and / or one or more exhaust aftertreatment component (s), which comprises an SCR coating, and / or a secondary air injection be educated.

In particular, the exhaust gas generated in the gasoline engine flows through the main catalytic converter and then through the SCR catalytic converter of the exhaust gas aftertreatment system.

In the reduction mode of the SCR catalytic converter, oxygen and in particular air, preferably ambient air, optionally filtered or compressed, is supplied to the SCR catalytic converter via a supply line. Preferably the

Supply line after the main catalytic converter and before the SCR catalytic converter into the exhaust gas aftertreatment system. By supplying oxygen, in particular air, the SCR catalytic converter can convert the nitrogen oxides emitted by the gasoline engine into nitrogen and water if the SCR catalytic converter or the exhaust gas flowing through the SCR catalytic converter is one

Has temperature which is greater than a reduction temperature, in particular greater than the NOx light off temperatures corresponding to the technology, preferably greater than 170 ° C.

The reduction of nitrogen monoxide NO essentially takes place at a reduction temperature of over 250 ° C according to the following regulation:

4JVO + 4 NH ₃ + 0 ₂ ^ 4 JV ₂ + 6 H ₂ 0

It is also possible that when both nitrogen monoxide and NO

Nitrogen dioxide NO2 is present in the exhaust gas and the reduction temperature is in the range of 170 ° C to 300 ° C, a so-called "fast SCR reaction" can take place. The fast SCR reaction essentially follows the following rule:

NO + 2NH ₃ + N0 ₂ -> 2 JV ₂ + 3 H ₂ 0

The reduction of nitrogen dioxide NO2 essentially follows the following rule:

8 NH ₃ + 6 N0 ₂ -> 7 JV ₂ + 12H ₂ 0

If necessary, it is provided that the SCR catalyst has the reducing agent required for the reactions, in particular ammonia Nhh, via a

Dosing device, in so-called active form, or as part of normal petrol engine operation and / or by changing the mode of operation of the gasoline engine, in a so-called passive form.

In contrast to conventional methods, it is not necessary to operate the gasoline engine periodically lean, i.e. with excess air. On the contrary: If a gasoline engine were operated lean periodically, a 3-way catalytic converter would be used don't work at all. An SCR catalytic converter is now provided, to which oxygen and in particular air are supplied via the supply line. in the

In contrast to methods known from the prior art, it may also be possible to operate and / or regulate the gasoline engine, in particular always, in a lambda window by l = 1. This may make it possible for the 3-way catalyst and the other components of the

Exhaust aftertreatment system always supply an essentially oxygen-free or low-oxygen exhaust gas.

The measures according to the invention make it possible to always keep the 3-way catalytic converter in a functional window and, at the same time, to further reduce emissions by operating the SCR catalytic converter. This is achieved in particular by supplying air to the SCR catalytic converter downstream of the 3-way catalytic converter.

During the reduction operation of the SCR catalytic converter, the oxygen content of the exhaust gas flowing through the main catalytic converter or of the exhaust gas located in the main catalytic converter and / or the optionally present pre- or secondary or heating catalytic converters can be less than 5% by volume or essentially zero.

During the reduction operation of the SCR catalytic converter, the amount of oxygen in the exhaust gas flowing through the main catalytic converter or the amount of oxygen in the main catalytic converter and / or possibly pre- or secondary or heating catalytic converter can be kept so low that the efficiency of the

Main catalyst and / or, if applicable, of the upstream or downstream or

Heating catalyst is largely unaffected and independent of the reduction operation of the SCR catalyst, so that at any time a sufficiently high, preferably the largest possible, pollutant emission conversion rate

Exhaust aftertreatment components in total is ensured.

In particular, the main catalytic converter, the main catalytic converters or the main catalytic converter (s) and the further exhaust gas aftertreatment components normally have, before the feed line flows into the exhaust gas aftertreatment system. as in the reduction mode, a high, preferably the best possible, efficiency.

It is preferably provided that only the SCR catalytic converter and an optionally provided gasoline particle filter are or are flowed through in the reduction mode with oxygen-containing gas, in particular air, preferably ambient air, optionally filtered or compressed.

Within the scope of the present invention, at least one of them is included

Main catalytic converter or the main catalytic converter to understand one or more catalytic converter (s), in particular several main catalytic converters, which have essentially the same effect and / or function. If appropriate, the at least one main catalyst comprises one or more catalysts, in particular one or more pre- or secondary catalysts and / or one or more

Heating catalyst / s. If appropriate, the at least one main catalytic converter is 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 heating catalytic converter (s). At least one of the abovementioned catalysts is preferably coated with a 3-way coating.

It is preferably provided that the method is carried out automatically, in particular in a control unit of a motor vehicle and / or controlled and / or regulated by a control unit of a motor vehicle.

If necessary, the reduction operation is ended after the SCR catalytic converter has completely or at least partially converted the nitrogen oxides contained in the exhaust gas.

If necessary, it is provided that the exhaust gas from the gasoline engine is fed to the main catalytic converter and the SCR catalytic converter in the normal operating phase, that the main catalytic converter is designed or acts as a 3-way catalytic converter and that the gasoline engine is operated in its normal operating phase in a lambda window by l = 1 or is regulated. In the normal operating phase, which essentially corresponds to the regular operating mode of the gasoline engine arrangement or gasoline engine, fuel and air are introduced into the combustion chamber of at least one cylinder of the gasoline engine and converted to exhaust gas by combustion.

In the normal operating phase, the gasoline engine can preferably be operated and / or regulated in a lambda window by l = 1. This means that the gasoline engine is optionally operated in a manner oscillating around a lambda value l of 1.0, and in particular is operated and / or regulated with a lambda value l in the range from 0.9 to 1.1, preferably from 0.95 to 1.05 becomes. It can be provided that the gasoline engine is operated and / or regulated in phases or permanently under or over stoichiometric or rich or lean in its normal operating phase,

provided the exhaust gas aftertreatment components of the gasoline engine arrangement permit a sufficiently high, in particular, under these conditions

best possible raw emissions conversion.

This may mean that both in the normal operating phase and in

Reduction operation a sufficient, preferably the largest possible

 The degree of conversion of the pollutants by the exhaust gas aftertreatment components should be ensured in total. This can be a sufficiently high

Pollutant reduction can be made possible in both operating phases. In particular, it is provided that the degree of pollutant emissions conversion of the

Exhaust gas treatment system at no time

 Pollutant emission conversion level falls below the threshold value, below which there is no longer a sufficiently high pollutant emission reduction. If necessary, it is provided that the

 Pollutant emission conversion degree threshold is as large as possible, especially in an area as close as possible to 100%.

In particular, it is provided that the exhaust gas generated by the gasoline engine is essentially oxygen-free in the normal operating phase and at most contains only small amounts of oxygen. It can be provided that the gasoline engine is operated in the reduced mode of the SCR catalytic converter as in the normal operating phase.

If necessary, it is provided that the SCR catalyst converts nitrogen monoxide NO to nitrogen N2 and water H2O in the reduction mode, this reaction essentially taking place according to the following regulation:

4 NO + 4NH ₃ + 0 ₂ ^ 4 N ₂ + 6 H ₂ 0 and / or that in the reduction mode, the SCR catalyst converts nitrogen monoxide NO and nitrogen dioxide NO2 to nitrogen N2 and water H2O, this reaction essentially according to the following regulation expires:

NO + 2NH ₃ + N0 ₂ -> 2 JV ₂ + 3 H ₂ 0 and / or that nitrogen dioxide NO2 is converted to nitrogen N2 and water H2O by the SCR catalyst in the reduction mode, this reaction in

The main procedure is as follows:

QNH ₃ + 6 N0 ₂ -> 7 N ₂ + 12 H ₂ 0

If necessary, it is provided that the oxygen volume flow or air volume flow supplied to the SCR catalytic converter, in particular unidirectionally, through the supply line is controlled or regulated, in particular via a supply valve.

Furthermore, a device regulating or preventing the introduction of air, in particular a supply valve, can be provided, with which the supply of oxygen, in particular the supply of air, can be controlled and / or regulated by the supply line.

In particular, it must be ensured that the supply line enters the

Exhaust aftertreatment system a safety device, such as a Check valve or a membrane, contains in order to prevent possible escape of the exhaust gas through the supply line into the environment in any case.

If necessary, it is provided that an operating fluid is introduced from a metering device upstream of the SCR catalytic converter into the exhaust gas aftertreatment system, the operating fluid containing a reducing agent for nitrogen oxide reduction or in one

Reducing agent for nitrogen oxide reduction can be implemented, and / or that one

Reducing agents for nitrogen oxide reduction, in particular ammonia NH3, are generated by the main catalytic converter, in particular by the 3-way catalytic converter, in the context of normal gasoline engine operation and / or by, if necessary, temporarily adjusting the gasoline engine operating parameters of the gasoline engine, in particular by operating the gasoline engine at substoichiometric levels. Within the scope of the invention, the fact that an operating fluid is introduced into the exhaust gas aftertreatment system from a dosing device upstream of the SCR catalytic converter is to be understood in such a way that it is already in the exhaust gas aftertreatment system and is not supplied externally, as is known, for example, in diesel engines.

It is particularly advantageous if the reducing agent is used for

Nitrogen oxide reduction is generated by the main catalytic converter, in particular by the 3-way catalytic converter, in the course of normal gasoline engine operation, in particular by the gasoline engine being operated at substoichiometric levels. NH3 is generated as a waste product in the 3-way catalytic converter, which means that no active addition of urea is necessary. The SCR catalytic converter is therefore operated passively: no urea has to be added, since it is generated by motor and / or regenerated.

Due to the temporary adjustment of the gasoline engine operating parameters, in particular the substoichiometric operation of the gasoline engine, it may be possible, as long as a sufficiently high, preferably the largest,

 Total pollutant emission conversion degree of the exhaust aftertreatment components is ensured.

If appropriate, it is provided that during operation, in particular during the reduction operation of the SCR catalytic converter, one is suitable for selective catalytic reduction Operating fluid, such as in particular a mixture containing urea, a urea solution or AdBlue®, is metered in before the SCR catalytic converter in a so-called active way. The operating material can contain a reducing agent, such as, in particular, ammonia NH3, or can be converted into a reducing agent, such as, in particular, NH3.

A urea-containing mixture, in particular a urea-water solution, such as AdBlue®, is preferably used as the operating medium, the

If necessary, the operating material is converted into the reducing agent, in particular NH3, by the reactions shown below:

Thermolysis: (.NH ₂ ) ₂ CO -> NH 3 + HNCO

Hydrolysis: HNCO + H ₂ 0 -> NH ₃ + C0 ₂

In a first step, the urea (NH2) 2CO can be converted into ammonia NH3 and isocyanic acid HNCO during the thermolysis reaction. In a second step, the isocyanic acid HNCO can be converted into ammonia NH3 and carbon dioxide CO2 with water H2O in the hydrolysis reaction.

The reducing agent, in particular NH3, can optionally be stored and / or stored at least temporarily in the SCR catalytic converter. The ammonia may accumulate at the active centers of the SCR catalytic converter. The at least temporarily stored reducing agent, in particular the ammonia NH3, can subsequently reduce nitrogen oxides NOx, such as in particular nitrogen monoxide NO and nitrogen dioxide NO2.

The operating fluid can be dosed via a dosing device, in particular via an injector or an injection nozzle.

It may be provided that the gasoline engine is operated in such a way that it generates a reducing agent, in particular hydrogen H2. The hydrogen H2 produced can be converted with the nitrogen monoxide NO generated in the main catalyst, in particular in a 3-way catalyst, to ammonia NH3 and water H2O essentially according to the following regulation: 2 NO + 5 H ₂ -> 2 NH ₃ + 2 H ₂ 0

This may make it possible to do what is necessary for the SCR reactions

Reducing agent for nitrogen oxide reduction, in particular ammonia Nhh, without a metering device, in a so-called passive way, only by the gasoline engine and the main catalytic converter.

If appropriate, it is provided that the exhaust gas aftertreatment system contains the main catalytic converter (s) and the SCR catalytic converter 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 are an oxidation catalytic converter Coating comprises / s, and / or one or more heating catalytic converter (s) and / or one or more, in particular gaseous exhaust gas aftertreatment, gasoline engine particle filter and / or one or more NOx storage catalytic converter (s) and / or one or more

 Exhaust aftertreatment component (s), which comprises a NOx storage catalytic converter coating, and / or one or more SCR system (s) and / or one or more exhaust aftertreatment component (s), which comprise an SCR coating, and / or comprises a secondary air injection or that the

Exhaust gas aftertreatment system from the main catalyst (s) and the SCR catalyst 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 have an oxidation catalyst coating

comprises / s, and / or one or more heating catalytic converter (s) and / or one or more gasoline particulate filter / s and / or one or more NOx storage catalytic converter (s) and / or one or more exhaust gas aftertreatment component (s) coated in particular with gaseous exhaust gas aftertreatment NOx storage catalytic converter coating (s) and / or one or more SCR system (s) and / or one or more exhaust gas aftertreatment component (s) comprising an SCR coating (s) and / or a secondary air injection is formed. If necessary, it is provided that the oxygen and in particular the air are fed to the SCR catalytic converter in its reduction mode via the feed line which leads after the main catalytic converter, in particular after a 3-way catalytic converter, and before the SCR catalytic converter into the exhaust gas aftertreatment system, or that Oxygen and especially the air in the SCR catalyst

Reduction mode is fed via the feed line leading into the exhaust gas aftertreatment system in front of a gasoline engine particle filter and upstream of the SCR catalytic converter, or that the oxygen and in particular the air in the reduction mode is fed to the SCR catalytic converter in the reduction mode via the after a gasoline engine particle filter and before the SCR catalyst into the exhaust gas aftertreatment system

Feed line is supplied.

It may be provided that the air is filtered and / or compressed

Ambient air.

If necessary, it is provided that ambient air is supplied to the SCR catalytic converter in the reduction mode and that the ambient air from the environment enters the supply line, in particular unidirectionally. Furthermore, the ambient air can be upstream of the SCR catalytic converter and after the main catalytic converter

Gasoline engine particle filter from the supply line, or before the gasoline engine particle filter and before the SCR catalytic converter and after the main catalytic converter from the

Exit supply line.

Where appropriate, it is provided that ambient air is supplied to the SCR catalytic converter in the reduction mode, that the ambient air from the environment,

in particular unidirectionally, enters the supply line, the ambient air upstream of the SCR catalytic converter and after the main catalytic converter and / or after the

Gasoline engine particle filter exits the supply line, or the air exits the supply line before the gasoline engine particle filter and before the SCR catalytic converter and after the main catalytic converter.

This means that in the reduction mode, ambient air can flow through the supply line and then through the SCR catalytic converter. In particular, it is provided that non-compressed air, in particular non-compressed ambient air, enters the supply line and exits the supply line before the SCR catalytic converter, in particular after the main catalytic converter.

If appropriate, it is provided that the ambient air is drawn in automatically by the exhaust gas flow present in the exhaust gas aftertreatment system

and that the ambient air into the through a venturi nozzle

Exhaust gas treatment system is introduced.

In particular, it can be provided that one end of the feed line opens into the surroundings, in particular outside the exhaust gas aftertreatment system, and the other end into the exhaust gas aftertreatment system.

Furthermore, a suppression can be present in the exhaust gas aftertreatment system or arise when exhaust gas is flowed through the exhaust gas aftertreatment system. It can thus be possible that air from the surroundings is sucked into the exhaust gas aftertreatment system, in particular upstream of the SCR catalytic converter, through the supply line, in particular automatically, by means of this suppression.

In particular, the ambient air can enter the venturi nozzle

Exhaust gas treatment system are introduced. If appropriate, it is provided that the exhaust gas aftertreatment system in the area in which the

Feed line opens into the exhaust gas aftertreatment system when a Venturi nozzle is formed.

If necessary, it is provided that air, in particular air compressed by a turbocharger of the gasoline engine, is fed to the SCR catalytic converter, that the air between a compressor and a charge air cooler of the turbocharger or between a charge air cooler of the turbocharger and the gasoline engine into the

Feed line enters, wherein the air after the main catalyst and / or optionally after the gasoline engine particulate filter and before the SCR catalyst exits the feed line, or wherein the air after the main catalyst and if necessary, upstream of the gasoline engine particle filter and upstream of the SCR catalytic converter and out of the supply line.

This means that in the reduction mode, air from the environment can flow through the compressor of the turbocharger, through the supply line and then through the SCR catalytic converter.

In particular, it is provided that air compressed by the compressor of the turbocharger enters the feed line after the compressor of the turbocharger and exits the feed line before the SCR catalytic converter, in particular after the main catalytic converter.

It is optionally provided that the exhaust gas and / or the air supplied in the reduction mode are heated by a heating element, that the heated air flows through the SCR catalytic converter and then through the SCR catalytic converter, and that the

Heating element is provided in front of the SCR catalytic converter.

If necessary, it is provided that a heating element for heating the SCR catalytic converter is provided after the gasoline engine and before the SCR catalytic converter, in particular in the front area of the SCR catalytic converter

and / or that after the gasoline engine and before the gasoline engine particle filter, in particular in the front area of the gasoline engine particle filter, a heating element is provided for heating the gasoline engine particle filter and / or that after the gasoline engine and in front of the main catalytic converter, in particular in the front area of the main catalytic converter

Heating element for heating the main catalyst is provided and / or that after the gasoline engine and before the secondary catalyst, in particular in the front area of the secondary catalyst, a heating element is provided for heating the secondary catalyst, the respective heating element itself preferably being catalytically actively coated.

The heating element or the heating elements can be powered by the vehicle electrical system, which in particular has a nominal voltage of 12 volts or 48 volts. If appropriate, it is provided that in front of each exhaust gas aftertreatment component of the exhaust gas aftertreatment system, in particular in the front area

Exhaust aftertreatment component, at least one heating element is provided. For example, the respective catalysts can reach the temperature (light-off temperature) required for their efficient function earlier.

In particular, provision is made for a heating element to be provided in front of the SCR catalytic converter in order to be able to heat the SCR catalytic converter quickly to its functional temperature, particularly when the internal combustion engine is cold started, and thus to reduce or prevent the emission of NOx emissions. Since the SCR catalytic converter generally requires a significantly lower temperature to function than the 3-way catalytic converter, the NOx emissions emitted by the gasoline engine can be absorbed by the SCR catalytic converter during a cold start

Furthermore, the heating elements and the heating of the individual catalysts which is made possible thereby can be used for their desulfurization.

If appropriate, it is provided that the gasoline engine arrangement is in an operating phase, the normal operating phase, possibly a coasting operating phase, and the

Regeneration operation, includes that the gasoline engine is operated and / or regulated in the lambda window preferably in a lambda window by l = 1, and that the overrun operation phase is formed by at least one unfired overrun operation phase and / or at least one fired overrun operation phase, that in the fired overrun operation phase Main gas flowing through the main catalyst is low in oxygen, in particular essentially oxygen-free, and in particular the exhaust gas of a stoichiometric or sub-stoichiometric one, in particular

is sometimes substoichiometric, combustion, wherein the gasoline engine in the unfired overrun operating phase is supplied with the exhaust gas via an exhaust gas recirculation line that was generated before or during the transition from the normal operating phase to the unfired overrun operating phase in the gasoline engine, or where

Gasoline engine in the unfired overrun phase that exhaust gas over a

Exhaust gas recirculation line is supplied, which was generated in the gasoline engine before or during the transition from a fired coasting phase to the unfired coasting phase. If appropriate, it is provided that the oxygen content of the exhaust gas located in the main catalyst or that the oxygen content of the exhaust gas flowing through the main catalyst in the unfired overrun operating phase essentially corresponds to the oxygen content of the exhaust gas flowing through the main catalyst in the normal operating phase or in the fired overrun operating phase.

If necessary, it is provided that the exhaust gas aftertreatment system

Main catalytic converter, optionally a gasoline engine particle filter, the SCR catalytic converter and optionally a NOx storage catalytic converter arranged downstream of the SCR catalytic converter, the regeneration mode of the

Otto engine particle filter the gasoline engine particle filter through one or the in the

Exhaust gas aftertreatment system opening supply line oxygen and

In particular air, preferably filtered and / or compressed ambient air, is supplied, and / or in the storage mode of the NOx storage catalytic converter, the NOx storage catalytic converter is supplied with oxygen and in particular air, preferably filtered and / or compressed ambient air, via one or the supply line leading into the exhaust gas aftertreatment system, is fed.

In particular, it is provided that introduced through the feed line

Combined use of oxygen, and with this oxygen to operate the gasoline engine particulate filter in its regeneration mode, the SCR catalytic converter in its reduction mode and / or the NOx storage catalytic converter in its storage mode.

As a result, it may be possible to regenerate a gasoline engine particulate filter positioned in front of the NOx storage catalytic converter in operating areas of the gasoline engine arrangement in which regeneration has hitherto not been possible due to lack of oxygen.

If appropriate, it is provided that the oxygen which supplies the gasoline engine particle filter, the SCR catalytic converter and the NOx storage catalytic converter

Feed line before the gasoline engine particle filter and after the main catalyst opens into the exhaust gas aftertreatment system. If necessary, the active initiation of the regeneration of the gasoline engine particulate filter in the gasoline engine arrangement is also necessary at the latest if through the

Particle loading of the exhaust gas back pressure exceeds an exhaust gas back pressure threshold value at which the exhaust gas emission is severely hampered and in particular potentially long-term damage-relevant component limit values of the engine or the exhaust gas aftertreatment system are exceeded.

The monitoring of the loading condition as well as the initiation and control of the regeneration of the gasoline engine particle filter can be done by the engine control of the

Internal combustion engine, in particular by the control unit of the

Internal combustion engine to be performed.

It is optionally provided that the gasoline engine particle filter, the

Oxidation catalytic converter, the NOx storage catalytic converter and / or the SCR catalytic converter is supplied with oxygen, in particular ambient air, via a supply line.

Alternatively, it is provided that the gasoline engine particle filter, the oxidation catalytic converter, the NOx storage catalytic converter and / or the SCR catalytic converter have their own

Supply line oxygen, especially ambient air, is supplied.

If appropriate, it is provided that if oxygen, in particular air, enters the

Exhaust gas treatment system is introduced, the oxygen content of the

Exhaust gas flowing through the main catalyst or the exhaust gas located in the main catalyst is less than 5% by volume or essentially zero, and / or that if

Oxygen, in particular air, is introduced into the exhaust gas aftertreatment system, the oxygen quantity of the exhaust gas flowing through the main catalyst or the oxygen quantity of the exhaust gas located in the main catalyst being kept so low that the efficiency of the main catalyst is unaffected.

If necessary, it is provided that the operating material is introduced via the metering device after the oxidation catalytic converter and before the SCR catalytic converter.

In particular, the invention relates to a gasoline engine arrangement, wherein the

Gasoline engine arrangement comprises a gasoline engine and an exhaust gas aftertreatment system, the exhaust gas aftertreatment system having a main catalytic converter and one

Main catalyst includes downstream SCR catalyst, being in one

In the normal operating phase in the gasoline engine, fuel and air are converted to an exhaust gas, the gasoline engine arrangement comprising a supply line which opens into the exhaust gas aftertreatment system and in particular can be flowed through unidirectionally, and the gasoline engine arrangement is set up to carry out the method according to the invention.

It may be provided that the gasoline engine is designed as a gasoline engine regulated in a lambda window by l = 1 in front of the exhaust gas aftertreatment system.

If appropriate, it is provided that the supply line opens into the exhaust gas aftertreatment system upstream of the SCR catalytic converter,

wherein the supply line branches off between a compressor and a charge air cooler of a turbocharger of the gasoline engine, or wherein the supply line branches off between a charge air cooler of a turbocharger of the gasoline engine and the gasoline engine, or wherein the supply line branches off between the air filter and a compressor of a turbocharger of the gasoline engine, or wherein the Feed line to

Introduction of air from the environment outside the gasoline engine arrangement to the ambient air is open.

It is optionally provided that the supply line opens into the exhaust gas aftertreatment system upstream of the SCR catalytic converter, the supply line comprising a blower which is fed from the intake tract and / or ambient air, and / or the supply line being a pressure accumulator, in particular one

Compressed air accumulator.

If appropriate, it is provided that a controllable and / or regulatable blower for conveying the oxygen, in particular for conveying the air, along the

Supply line is provided. In particular, the blower can be used as

Secondary air pump, be designed as an electrical compressor or mechanical compressor. It is optionally provided that the supply line opens into the exhaust gas aftertreatment system in front of the SCR catalytic converter and / or that the supply line for introducing air from the environment outside the gasoline engine arrangement to the ambient air, in particular unidirectionally, in the direction of the

Exhaust gas aftertreatment system is open, and / or that the ambient air is automatically drawn into the exhaust gas aftertreatment system by the exhaust gas flow present in the exhaust gas aftertreatment system and / or that the ambient air is introduced into the exhaust gas aftertreatment system via a venturi nozzle.

If necessary, it is provided that a controllable and / or adjustable blower and / or a pressure accumulator is / are provided along the supply line.

If necessary, the blower can fill the pressure reservoir, continuously or discontinuously, which in turn serves as an oxygen reservoir, in particular an air reservoir. The pressure accumulator can be in the supply line between the fan and the mouth of the supply line in the

Exhaust aftertreatment system is arranged.

If appropriate, provision is made for air to be introduced into the exhaust gas aftertreatment system from the pressure reservoir filled with air via the supply line.

It may be provided that the gasoline engine particle filter is uncoated or as a 2-way catalytic converter or as a 3-way catalytic converter or as a 4-way catalytic converter, or that the gasoline engine particle filter is not a catalytic converter or a 2-way catalytic converter or a 3-way catalytic converter -Catalyst or includes a 4-way catalyst.

It can be provided that the gasoline engine particle filter is uncoated in its embodiment and is only set up to filter particles.

It can be provided that the gasoline engine particle filter is set up to filter particles and additionally, or in combination, hydrocarbons,

Implement and / or store carbon monoxide and nitrogen oxides. This is the Depending on the coating, the gasoline engine particle filter is designed as a 2, 3 or 4-way catalytic converter.

If appropriate, it is provided that the gasoline engine particle filter comprises the SCR catalytic converter, the SCR catalytic converter being arranged in the rear region of the gasoline engine particle filter, and / or that a coating acting as SCR catalyst, such as, in particular, vanadium, an iron zeolite, or on the gasoline engine particle filter a copper zeolite is provided, the coating acting as an SCR catalyst preferably in the flow direction of the exhaust gas from the rear of the

Petrol engine particle filter is applied.

If appropriate, it is provided that between the main catalyst and the

Gasoline engine particle filter an oxidation catalyst coated with an oxidation catalyst coating is provided, or that the gasoline engine particle filter is provided at least in its front area with an oxidation catalyst coating, the oxidation catalyst coating being set up to convert NO with O2 to NO2.

If appropriate, it is provided that after the gasoline engine and before

Main catalyst, in particular in the front area of the main catalyst, a, in particular catalytically coated, heating element for heating the

Main catalytic converter is provided, and / or that after the gasoline engine, in particular after the main catalytic converter, and before the oxidation catalytic converter, in particular in the front region of the oxidation catalytic converter, one, in particular catalytically

coated heating element is provided for heating the oxidation catalyst, and / or that after the gasoline engine, in particular after the oxidation catalyst, and before the gasoline engine particle filter, in particular in the front area of the

Gasoline engine particle filter, a, in particular catalytically coated heating element, is provided for heating the gasoline engine particle filter, and / or after

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, in particular catalytically coated, heating element for heating the NOx storage catalytic converter is provided. If appropriate, it is provided that the gasoline engine arrangement has a gasoline engine and an exhaust gas aftertreatment system with at least the main catalytic converter, the

Gasoline engine particulate filter and a NOx storage catalyst that the

Main catalyst is designed as a 3-way catalyst or acts that

Main catalytic converter of the gasoline engine particle filter, which optionally acts as a 4-way catalytic converter, is arranged downstream that the gasoline engine particle filter is followed by the NOx storage catalytic converter, and if necessary one or more

Oxidation catalyst is arranged in front of the NOx storage catalyst.

If necessary, it is provided that the NOx storage catalytic converter in

Exhaust gas flow direction is the last catalyst of the

Exhaust aftertreatment system is.

In the context of the present invention, a front area of an exhaust gas aftertreatment component is to be understood as the area which is in

Flow direction of the exhaust gas in the respective exhaust aftertreatment component is flowed through earlier by the exhaust gas. In particular, this can be the area through which the exhaust gas enters the respective exhaust gas aftertreatment component.

In the context of the present invention, a rear area is one

Exhaust aftertreatment component to understand the area which in

Flow direction of the exhaust gas in the respective exhaust gas aftertreatment component is later flowed through by the exhaust gas. In particular, this can be the area through which the exhaust gas emerges from the respective exhaust gas aftertreatment component.

Further features according to the invention may result from 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 exemplary embodiments. 1 a, 1 b, 1 c, 1 d, 1 e, 1f, 1 g and 1 h show a schematic graphic representation of different variants of a first embodiment of the gasoline engine arrangement according to the invention,

 2a, 2b, 2c and 2d show a schematic graphic representation of different variants of a second embodiment of the invention

Gasoline engine arrangement,

 3 shows a schematic diagram of a third embodiment of the gasoline engine arrangement according to the invention, and

 4a and 4b show a schematic graphic representation of different variants of a fourth embodiment of the gasoline engine arrangement according to the invention.

Unless otherwise stated, the reference symbols correspond to the following

Components:

 Gasoline engine 1, exhaust gas aftertreatment system 2, fluff catalyst 3,

 Gasoline engine particle filter 4, turbocharger 5, throttle valve 6, compressor 7, turbine 8, exhaust gas recirculation line 9, NOx storage catalytic converter 10, venturi nozzle 11, supply valve 12, charge air cooler 13, supply line 14, SCR catalytic converter 15, further main catalytic converter 16, metering device 17, heating element 18, filter device 19, safety device 20, pressure accumulator 21 and blower 22.

1 a, 1 b, 1 c, 1 d, 1 e, 1f, 1 g and 1 h show schematic graphical representations of different variants of a first 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 .

 In this embodiment, the gasoline engine arrangement comprises a gasoline engine 1 and an exhaust gas aftertreatment system 2. The exhaust gas aftertreatment system 2 comprises a main catalytic converter 3 and an SCR catalytic converter 15 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 connected directly thereafter arranged on the turbine 8 of the turbocharger 5, in particular close to the engine.

Alternatively, the exhaust gas aftertreatment system 2 comprises a main catalytic converter 3, a gasoline engine particle filter 4 arranged downstream of the main catalytic converter 3, and one Gasoline engine particle filter 4 downstream SCR catalytic converter 15 and optionally a NOx storage catalytic converter 10 downstream of the SCR catalytic converter 15.

Furthermore, the gasoline engine arrangement of FIGS. 1 a, 1 b, 1 c, 1 d, 1 e, 1f, 1 g and 1 h comprises a turbocharger 5 and a throttle valve 6. The turbocharger 5 comprises one

Compressor 7 and a turbine 8. According to FIG. 1 b, the gasoline engine arrangement compared to the gasoline engine arrangement of FIG. 1 a additionally comprises an exhaust gas recirculation line 9, namely a flock pressure EGR line of a high pressure EGR system.

In the normal operating phase, which corresponds to the regular operation of the gasoline engine arrangement, fuel is supplied to the gasoline engine 1. The fuel is in the

Normal operating phase with air converted to an exhaust gas.

In the normal operating phase, the gasoline engine 1 is operated and / or regulated in a lambda window by l = 1. This means that the gasoline engine 1 is operated oscillating by a lambda value l of 1.0, and in particular is operated and / or regulated in the range from l = 0.9 to 1.1, preferably from l = 0.95 to 1.05 becomes. According to this embodiment it can be provided that the gasoline engine 1 in its

Normal operating phase is operated in phases or permanently rich or lean and / or regulated.

According to this embodiment, the exhaust gas emitted by the gasoline engine 1 in the normal operating phase is essentially oxygen-free. According to this embodiment, the gasoline engine 1 is operated in the reduction mode of the SCR catalytic converter 15 essentially the same as in the normal operating phase. That means that also in

Reduced operation, the exhaust gas emitted by the gasoline engine 1 is essentially oxygen-free.

In all embodiments, it is provided that the oxygen quantity of the exhaust gas flowing through the main catalyst 3 during the reduction operation of the SCR catalyst 15 or the oxygen quantity of the exhaust gas located in the main catalyst 3 is so small that the efficiency of the main catalyst 3 is essentially unaffected. As a result, the effectiveness, in particular the efficiency, of the main catalytic converter 3 is in particular of the 3-way catalytic converter, essentially the same before and after the reduction operation of the SCR catalytic converter 15.

In particular, it can be provided that the oxygen content of the

Exhaust gas flowing through the main catalytic converter 3 or the exhaust gas located in the main catalytic converter 3 during the reduction operation of the SCR catalytic converter 15 is less than 5% by volume or is essentially zero.

This makes it possible to solve the conflict of objectives mentioned above and to create a method and a gasoline engine arrangement which enables low fuel consumption and low pollutant emissions.

In this way, even in the reduction mode, comparatively hot engine exhaust gas remains essentially without free oxygen in the main catalytic converter 3. As a result, any storage of oxygen in the main catalytic converter 3 that may occur and the subsequent rich operation of the gasoline engine 1 that may be necessary as a result can be avoided.

In the reduction mode of the SCR catalytic converter 15, oxygen, in particular air, is supplied to the SCR catalytic converter 15 through a supply line 14 according to this embodiment.

According to this embodiment, the supply line 14 opens before the SCR catalytic converter 15 into the exhaust gas aftertreatment system 2 and branches off between the compressor 7 and the charge air cooler 13 of the turbocharger 5.

This means that the oxygen and in particular the air in the reduced mode of the SCR catalytic converter 15 is air compressed by a turbocharger 5 of the gasoline engine 1. Furthermore, the compressed air after the compressor 7 and before the charge air cooler 13 of the turbocharger 5 enters the supply line 14 and after the main catalytic converter 3 and before the SCR catalytic converter 15 from the supply line 14. According to this embodiment, in the supply line 14 a device regulating or preventing the introduction of air, namely a supply valve 12, is provided, with which the oxygen supply, in particular the air supply, is controlled and / or regulated by the supply line 14.

The gasoline engine 1 generates both in the normal operating phase and in

Reduction operation of the SCR catalytic converter 15 through the conversion of fuel to an exhaust gas. This exhaust gas first flows through the turbine 8 of the turbocharger 5 and then through the exhaust gas aftertreatment components of the exhaust gas aftertreatment system 2 before it exits into the environment.

In the reduction mode of the SCR catalytic converter 15, the nitrogen oxides contained in the exhaust gas are partially or completely converted to water and nitrogen in or on the SCR catalytic converter 15.

According to FIGS. 1 a, 1 b, 1 d, 1 e, 1 f, 1 g and 1 h, the reducing agent, the ammonia, for the reduction of the nitrogen oxides in the SCR catalytic converter 15 is generated by the 3-way catalytic converter. For this purpose, the gasoline engine 1 is operated such that the gasoline engine 1 generates hydrogen, for example. The hydrogen generated is then converted to ammonia in a 3-way catalyst with nitrogen monoxide. Alternatively, a dosing device 17 for dosing the operating material can be provided in this variant.

According to FIG. 1 c, the operating material is introduced into the exhaust gas aftertreatment system 2 via a metering device 17 upstream of the SCR catalytic converter 15.

According to FIG. 1 d, the supply line 14 opens before the gasoline engine particle filter 4, which includes the SCR catalytic converter 15, into the exhaust gas aftertreatment system 2. According to this figure, the SCR catalytic converter 15 is in the rear region of the

Otto engine particle filter 4 arranged. Here, the coating acting as an SCR catalytic converter 15 is in the flow direction of the exhaust gas from the rear of the

Petrol engine particle filter 4 applied. According to FIG. 1 e, an NOx storage catalytic converter 10 is additionally arranged after the SCR catalytic converter 15 or the gasoline engine particle filter 4, which comprises the SCR catalytic converter 15.

According to the variant shown in FIG. 1f, in addition to the variant shown in FIG. 1a, a further flaking catalytic converter 16 and a gasoline engine particle filter 4 are arranged between the flaking catalytic converter 3 and the SCR catalytic converter 15.

According to the variant shown in FIG. 1 g, in addition to the variant shown in FIG. 1 f, a fleece element 18 is arranged in front of the fluff catalyst 3.

According to the variant shown in FIG. 1 h, in addition to the variant shown in FIG. 1 g, a fleece element 18 is arranged in front of the SCR catalytic converter 15.

2a, 2b, 2c and 2d show schematic representations of different variants of a second embodiment of an inventive

Gasoline engine arrangement 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, 2c and 2d can preferably correspond to the features of the embodiments according to FIGS. 1 a, 1 b, 1 c, 1 d, 1 e, 1 f, 1 g and 1 h.

In contrast to the variants of the first embodiment, that for the

Reduction operation of the SCR catalytic converter 15, necessary oxygen, in particular the air, is introduced into the exhaust gas aftertreatment system 2 through a venturi nozzle 11.

Furthermore, a feed valve 12 is arranged on the feed line 14 and is used to regulate the amount of oxygen and to the SCR catalytic converter 15

especially the air is set up.

Fig. 3 shows a schematic representation of a third embodiment of a gasoline engine arrangement according to the invention, which for performing the

method is suitable and / or set up. The features of the embodiment according to FIG. 3 can preferably match the features of FIG Embodiments according to Figures 1 a, 1 b, 1 c, 1 d, 1 e, 1f, 1 g, 1 h, 2a, 2b, 2c and 2d correspond.

According to this embodiment, the exhaust gas aftertreatment system 2 comprises a main catalytic converter 3, a gasoline engine particle filter 4 and an SCR catalytic converter 15.

The ambient air filtered by a filter device 19 is introduced into the exhaust gas aftertreatment system 2 via a Venturi nozzle 11. Furthermore, a feed valve 12 and a safety device 20 are on the feed line 14

intended.

4a and 4b show schematic representations of different variants of a fourth 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. 4a and 4b can preferably correspond to the features of the embodiments according to FIGS. 1a, 1b, 1c, 1d,

1 e, 1f, 1 g, 1 h, 2a, 2b, 2c, 2d and 3 correspond.

The exhaust gas aftertreatment system 2 comprises a main catalytic converter 3, a further main catalytic converter 16, a gasoline engine particle filter 4 and an SCR catalytic converter 15.

4a, the filtered ambient air is optionally introduced into a pressure accumulator 21 or directly into the exhaust gas aftertreatment system 2 by a fan 22, which in this embodiment is designed as an electrical compressor 7.

Furthermore, the stored ambient air from the pressure accumulator 21 into the

Exhaust gas treatment system 2 are introduced.

According to the variant shown in FIG. 4b, in contrast to the variant shown in FIG. 4a, the ambient air is extracted from the intake tract

Gasoline engine arrangement sucked in by the blower 22. This means that the fan 22 branches off air in front of the compressor 7 of the turbocharger 5 of the gasoline engine arrangement. The effects according to the invention can be achieved by means of this exemplary configuration.

The invention is not limited to the illustrated embodiments, but includes any method and any gasoline engine arrangement according to the

subsequent claims.

Claims

Claims 1. Method for operating a gasoline engine arrangement,  the gasoline engine arrangement comprising a gasoline engine (1) and a  Exhaust gas aftertreatment system (2) comprises  the exhaust gas aftertreatment system (2) at least one  Main catalytic converter (3) and an SCR catalytic converter (15) arranged downstream of the main catalytic converter (3),  and in a normal operating phase in the gasoline engine (1), fuel and air are converted into exhaust gas,  characterized,  that in the reduction mode of the SCR catalytic converter (15) the SCR catalytic converter (15) for reducing the nitrogen oxides via a  Exhaust gas aftertreatment system (2) opening supply line (14) oxygen and in particular air, preferably ambient air,  optionally filtered or compressed, is fed,  the oxygen content of the exhaust gas flowing through the main catalyst (3) in the reduction mode being less than 5% by volume or essentially zero,  and / or wherein the amount of oxygen of 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. 2. The method according to claim 1, characterized in that  that the exhaust gas from the gasoline engine (1) is fed to the main catalytic converter (3) and the SCR catalytic converter (15) in the normal operating phase, that the main catalytic converter (3) is designed or acts as a 3-way catalytic converter  and that the gasoline engine (1) is operated or regulated in its lambda window by l = 1 in its normal operating phase. 3. The method according to claim 1 or 2, characterized in that the SCR catalytic converter (15) converts nitrogen monoxide NO to nitrogen N2 and water H2O in the reduction mode, this conversion essentially taking place according to the following regulation: 4 NO + 4NH ₃ + 0 ₂ ^ 4 N ₂ + 6 H ₂ 0 and / or that in the reduction mode of the SCR catalytic converter (15) nitrogen monoxide NO and nitrogen dioxide NO2 are converted to nitrogen N2 and water H2O, this reaction essentially runs according to the following regulation: NO + 2NH ₃ + N0 ₂ -> 2 JV ₂ + 3 H ₂ 0 and / or that the SCR catalytic converter (15) converts nitrogen dioxide NO2 to nitrogen N2 and water H2O in the reduction mode, this reaction essentially according to the following regulation expires: QNH ₃ + 6 N0 ₂ -> 7 N ₂ + 12 H ₂ 0 4. The method according to any one of the preceding claims, characterized in that the SCR catalyst (15) through the feed line (14),  in particular unidirectional, supplied oxygen volume flow or  Air volume flow, in particular controlled or regulated via a feed valve (12). 5. The method according to any one of the preceding claims, characterized in that an operating fluid is introduced from a metering device (17) upstream of the SCR catalytic converter (15) into the exhaust gas aftertreatment system (2), the operating fluid containing or in a reducing agent for nitrogen oxide reduction Reducing agent for nitrogen oxide reduction can be implemented, and / or that a reducing agent for nitrogen oxide reduction, in particular ammonia NH3, through the main catalytic converter (3), in particular through the 3-way catalytic converter, in the context of normal petrol engine operation and / or by possibly temporarily adjusting the gasoline engine operating parameters of the gasoline engine (1), in particular by the gasoline engine (1)  is operated substoichiometrically, is generated. 6. The method according to any one of the preceding claims, characterized  featured,  that the exhaust gas aftertreatment system (2) the main catalytic converter (s) (3) and the SCR catalytic converter (15) 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 / r comprises an oxidation catalytic converter coating, and / or one or more heating catalytic converter (s) and / or one or more gas engine particle filters (4) and / or one or more NOx storage catalytic converter (s), in particular coated with gaseous exhaust gas aftertreatment ) and / or one or more exhaust gas aftertreatment component (s), 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, which comprise an SCR coating, and / or comprises a secondary air injection,  or that the exhaust gas aftertreatment system (2) from the / the  Main catalyst (s) (3) and the SCR catalyst (15) 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 comprise an oxidation catalyst coating, and / or one or more heating catalyst (s) and / or one or more, in particular gaseous  Exhaust gas aftertreatment-coated, gasoline engine particle filter (s) (4) and / or one or more NOx storage catalytic converter (s) (10) and / or one or more exhaust gas aftertreatment component (s), which comprises a NOx storage catalytic converter coating, and / or one or more SCR system (s) and / or one or more Exhaust aftertreatment component / s, which comprises an SCR coating (s), and / or a secondary air injection is formed. 7. The method according to any one of the preceding claims, characterized  featured,  that the oxygen and in particular the air in the SCR catalytic converter (15) in its reduction mode via the after the main catalytic converter (3), in particular after a 3-way catalytic converter, and before the SCR catalytic converter (15) into the exhaust gas aftertreatment system (2) opening supply line (14) is supplied,  or that the oxygen and in particular the air are fed to the SCR catalytic converter (15) in its reduction mode via the feed line (14) leading into the exhaust gas aftertreatment system (2) before an Otto engine particle filter (4) and before the SCR catalytic converter (15),  or that the oxygen and in particular the air are fed to the SCR catalytic converter (15) in its reduction mode via the feed line (14) which opens into the exhaust gas aftertreatment system (2) after an Otto engine particle filter (4) and before the SCR catalytic converter (15). 8. The method according to any one of the preceding claims, characterized  featured,  that the SCR catalytic converter (15) is supplied with ambient air in the reduction mode,  that the ambient air from the environment, in particular unidirectionally, enters the supply line (14),  the ambient air before the SCR catalytic converter (15) and after the main catalytic converter (3) and / or after the gasoline engine particle filter (4) exits from the supply line (14),  or the air from the gasoline engine particulate filter (4) and upstream of the SCR catalytic converter (15) and after the main catalytic converter (3)  Feed line (14) emerges. 9. The method according to claim 8, characterized in that the ambient air automatically through the in the  Exhaust gas aftertreatment system (2) existing exhaust gas flow is sucked in,  and that the ambient air via a venturi nozzle (11) into the  Exhaust gas treatment system (2) is introduced. 10. The method according to any one of the preceding claims, characterized  featured,  that air, in particular air compressed by a turbocharger (5) of the gasoline engine (1), is supplied to the SCR catalytic converter (15), that the air between a compressor (7) and a charge air cooler (13) of the turbocharger (5) or enters the supply line (14) between a charge air cooler (13) of the turbocharger (5) and the gasoline engine (1),  the air after the main catalytic converter (3) and / or optionally after the gasoline engine particle filter (4) and before the SCR catalytic converter (15) exits from the supply line (14),  or wherein the air exits after the main catalytic converter (3) and optionally before the gasoline engine particle filter (4) and before the SCR catalytic converter (15) and from the supply line (14). 11. The method according to any one of the preceding claims, characterized  featured,  that after the gasoline engine (1) and before the SCR catalytic converter (15),  in particular in the front area of the SCR catalytic converter (15) Heating element (18) is provided for heating the SCR catalytic converter (15), and / or that after the gasoline engine (1) and before the gasoline engine particle filter (4), in particular in the front area of the gasoline engine particle filter (4), a heating element (18) is provided Heating of the gasoline engine particle filter (4) is provided and / or that a heating element (18) is provided for heating the main catalyst (3) after the gasoline engine (1) and before the main catalytic converter (3), in particular in the front area of the main catalytic converter (3) , and / or that a heating element (18) for heating the secondary catalyst is provided after the gasoline engine (1) and before the secondary catalyst, in particular in the front area of the secondary catalyst,  wherein the respective heating element (18) is preferably itself catalytically active. 12. The method according to any one of the preceding claims, characterized  featured,  that the gasoline engine assembly is in an operating phase, the  Normal operating phase, possibly an overrun phase and the regeneration mode,  that the gasoline engine (1) is operated and / or regulated in the lambda window preferably by l = 1 in the normal operating phase,  that the overrun phase by at least one unfired  Overrun phase and / or at least one fired overrun phase is formed,  that in the fired overrun phase, the gas flowing through the main catalyst (3) is low in oxygen, in particular essentially  is oxygen-free, and in particular is the exhaust gas from a stoichiometric or substoichiometric, in particular phase-by-phase stoichiometric, combustion,  The gasoline engine (1) in the unfired overrun operating phase is supplied with that exhaust gas via an exhaust gas recirculation line (9) which is before or during the transition from the normal operating phase to the unfired one  Overrun phase in the gasoline engine (1) was generated,  or wherein the gasoline engine (1) in the unfired overrun operating phase is supplied with the exhaust gas via an exhaust gas recirculation line (9) that was generated before or during the transition from a fired overrun operating phase to the unfired overrun operating phase in the Otto engine (1). 13. The method according to any one of the preceding claims, characterized  characterized in that the oxygen content of the in the main catalyst (3) located exhaust gas or that the oxygen content of the main catalyst (3) Exhaust gas flowing through in the unfired overrun operating phase essentially the oxygen content of the main catalyst (3)  flowing exhaust gas in the normal operating phase or in the fired overrun operating phase. 14. The method according to any one of the preceding claims, characterized  featured,  that the exhaust gas aftertreatment system (2) comprises the main catalytic converter (3), optionally a gasoline engine particle filter (4), the SCR catalytic converter (15) and optionally a NOx storage catalytic converter (10) downstream of the SCR catalytic converter (15),  wherein in the regeneration mode of the gasoline engine particle filter (4)  Gasoline engine particulate filter (4) over or in the  Exhaust gas aftertreatment system (2) opening supply line (14) oxygen and in particular air, preferably filtered and / or compressed ambient air, is supplied,  and / or wherein in the storage operation of the NOx storage catalytic converter (10) the NOx storage catalytic converter (10) via one or more in the  Exhaust gas treatment system (2) opening supply line (14) oxygen and in particular air, preferably filtered and / or compressed ambient air, is supplied. 15. The method according to any one of the preceding claims, characterized  featured,  that when oxygen, especially air, enters the  Exhaust gas treatment system (2) is introduced, the oxygen content of the exhaust gas flowing through the main catalyst (3) or in  Main catalyst (3) located exhaust gas is less than 5 vol .-% or substantially zero,  and / or that when oxygen, especially air, enters the Exhaust gas treatment system (2) is introduced, the amount of oxygen flowing through the main catalyst (3) of the exhaust gas or the amount of oxygen of the exhaust gas located in the main catalyst (3) is kept so low that the efficiency of the main catalyst (3) is unaffected. 16. The method according to any one of the preceding claims, characterized  characterized in that the operating material is introduced via the metering device (17) after the oxidation catalytic converter and before the SCR catalytic converter (15). 17. Otto engine arrangement,  the gasoline engine arrangement comprising a gasoline engine (1) and a  Exhaust gas aftertreatment system (2) comprises  The exhaust gas aftertreatment system (2) comprises a main catalytic converter (3) and an SCR catalytic converter (15) arranged downstream of the main catalytic converter (3),  in a normal operating phase in the gasoline engine (1), fuel and air are converted into exhaust gas,  The gasoline engine arrangement comprises a feed line (14) which opens into the exhaust gas aftertreatment system (2) and in particular can be flowed through unidirectionally,  characterized,  that the gasoline engine arrangement is set up to carry out the method according to one of claims 1 to 16. 18. Otto engine arrangement according to claim 17, characterized in that the  The gasoline engine (1) is designed as a gasoline engine (1) regulated in front of the exhaust gas aftertreatment system (2) in a lambda window by l = 1. 19. Otto engine arrangement according to claim 17 or 18, characterized in  that the feed line (14) opens before the SCR catalytic converter (15) into the exhaust gas aftertreatment system (2), wherein the feed line (14) branches off between a compressor (7) and a charge air cooler (13) of a turbocharger (5) of the gasoline engine (1), or wherein the feed line (14) between a charge air cooler (13) of a turbocharger (5) of the gasoline engine (1) and the gasoline engine (1) branches, or wherein the feed line (14) branches off between the air filter and a compressor (7) of a turbocharger (5) of the gasoline engine (1), or wherein the feed line (14) is open to the ambient air for introducing air from the environment outside the gasoline engine arrangement. 20. Otto engine arrangement according to one of claims 17 to 19, characterized  featured,  that the feed line (14) opens into the exhaust gas aftertreatment system (2) upstream of the SCR catalytic converter,  the feed line (14) comprising a blower (22) which is fed from the intake tract and / or ambient air,  and / or wherein the supply line (14) comprises a pressure accumulator (21), in particular a compressed air accumulator. 21. Otto engine arrangement according to one of claims 17 to 20, characterized  featured,  that the feed line (14) opens before the SCR catalytic converter (15) into the exhaust gas aftertreatment system (2),  and / or that the supply line (14) for introducing air from the environment outside the gasoline engine arrangement to the ambient air, in particular unidirectionally, is open in the direction of the exhaust gas aftertreatment system (2),  and / or that the ambient air automatically by the in the  Exhaust gas aftertreatment system (2) existing exhaust gas flow is sucked into the exhaust gas aftertreatment system (2),  and / or that the ambient air is introduced into the exhaust gas aftertreatment system (2) via a venturi nozzle (11). 22. Otto engine arrangement according to one of claims 17 to 21, characterized featured, that the gasoline engine particle filter (4) is uncoated or is designed as a 2-way catalytic converter, or as a 3-way catalytic converter, or as a 4-way catalytic converter,  or that the gasoline engine particle filter (4) does not comprise a catalytic converter, or a 2-way catalytic converter, or a 3-way catalytic converter or a 4-way catalytic converter. 23. Otto engine arrangement according to one of claims 17 to 22, characterized  featured,  that the gasoline engine particle filter (4) comprises the SCR catalytic converter (15), the SCR catalytic converter (15) being arranged in the rear region of the gasoline engine particle filter (4),  and / or that a coating acting as an SCR catalyst (15), such as in particular vanadium, an iron zeolite or a copper zeolite, is provided on the gasoline engine particle filter (4), the coating acting as an SCR catalyst (15) preferably is applied in the flow direction of the exhaust gas from the rear of the gasoline engine particle filter (4). 24. Otto engine arrangement according to one of claims 17 to 23, characterized  featured,  that between the main catalyst (3) and the gasoline engine particle filter (4) is coated with an oxidation catalyst coating  Oxidation catalyst is provided  or that the gasoline engine particle filter (4) is provided with an oxidation catalyst coating at least in its front area,  wherein the oxidation catalyst coating is set up to convert NO with O2 to NO2. 25. Otto engine arrangement according to one of claims 17 to 24, characterized  featured, that after the gasoline engine (1) and upstream of the main catalytic converter (3), in particular in the front area of the main catalytic converter (3), one, in particular catalytically coated heating element (18) is provided for heating the main catalyst (3),  and / or that after the gasoline engine (1), in particular after the  Main catalyst (3), and in front of the oxidation catalyst, in particular in the front area of the oxidation catalyst, a, in particular catalytically coated, heating element (18) is provided for heating the oxidation catalyst,  and / or that after the gasoline engine (1), in particular after the  Oxidation catalyst, and in front of the gasoline engine particle filter (4), in particular in the front area of the gasoline engine particle filter (4), a, in particular catalytically coated, heating element (18) for heating the  Gasoline engine particle filter (4) is provided,  and / or that after the gasoline engine, especially after the  Gasoline engine particle filter (4), and in front of a NOx storage catalytic converter (10), in particular in the front area of the NOx storage catalytic converter (10), a, in particular catalytically coated, heating element (18) is provided for heating the NOx storage catalytic converter (10). 26. Otto engine arrangement according to one of claims 17 to 25, characterized  featured,  that the gasoline engine arrangement a gasoline engine (1) and a  Exhaust gas aftertreatment system (2) with at least the main catalytic converter (3), the gasoline engine particle filter (4) and a NOx storage catalytic converter (10),  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 (4), which may act as a 4-way catalytic converter,  that the gasoline particle filter (4) is followed by the NOx storage catalytic converter (10), and that one or the oxidation catalytic converter is optionally arranged upstream of the NOx storage catalytic converter (10). 27. Gasoline engine arrangement according to one of claims 17 to 26, characterized in that the NOx storage catalytic converter (10) in the flow direction of the exhaust gas is the last catalyst of the exhaust gas aftertreatment system (2).