DE102017100892A1 - Regeneration of a particulate filter or four-way catalytic converter in an exhaust system of an internal combustion engine - Google Patents

Abstract

The invention relates to a method for the regeneration of a particulate filter or a four-way catalyst in an exhaust system of an internal combustion engine, wherein an increase in nitrogen oxide emissions during the regeneration of the particulate filter or the four-way catalyst should be prevented or at least minimized. It is provided that in the exhaust system of an internal combustion engine, a particulate filter or a four-way catalytic converter and a NOx storage catalytic converter are arranged, wherein the NOx emissions occurring in a lean operation of the internal combustion engine for the regeneration of the particulate filter or the four-way catalytic converter in the NOx Storage catalytic converter are cached and regenerated in a subsequent engine fat phase of the NOx storage catalyst.

Description

The invention relates to a device and a method for the regeneration of a particulate filter or a four-way catalytic converter in an exhaust system of an internal combustion engine.

The continuous tightening of the exhaust emission legislation places high demands on the vehicle manufacturers, which are solved by appropriate measures for the reduction of the engine raw emissions and by a corresponding exhaust aftertreatment. With the introduction of the legislative level EU6, a limit value for gasoline engines is prescribed for a number of particles, which in many cases necessitates the use of an Otto particle filter. When driving, such a gasoline particulate filter is loaded with soot. So that the exhaust gas backpressure does not increase too much, this Otto particle filter must be regenerated continuously or periodically. In order to carry out a thermal oxidation of the soot retained in the Otto particle filter with oxygen, a sufficiently high temperature level in conjunction with simultaneously existing oxygen in the exhaust system of the gasoline engine is necessary. Since modern gasoline engines are normally operated without oxygen surplus with a stoichiometric combustion air ratio (λ = 1), additional measures are required. These come as measures, for example, a temperature increase by a Zündwinkelverstellung, a temporary lean adjustment of the gasoline engine, the injection of secondary air into the exhaust system or a combination of these measures in question. An ignition angle adjustment in the direction of late in combination with a lean adjustment of the gasoline engine is preferably used so far, since this method requires no additional components and can deliver a sufficient amount of oxygen in most operating points of the gasoline engine. Furthermore, the aim is to bring the catalysts in the exhaust passage of the internal combustion engine after a cold start as quickly as possible to an operating temperature in order to achieve as fast as possible a high conversion rate for harmful exhaust gas components. However, this lean adjustment of the internal combustion engine during the regeneration of the particulate filter can lead to a significant increase in nitrogen oxide (NOx) emissions during the regeneration of the particulate filter, since no components such as carbon monoxide (CO) are present in the exhaust gas at a lean of stoichiometric combustion air ratio. or unburned hydrocarbons (HC) are more, with which on the three-way catalyst, a catalytic reduction of nitrogen oxide emissions to molecular nitrogen is possible.

From the DE 10 2013 220 899 A1 a method for the regeneration of a particulate filter in an exhaust system of an internal combustion engine is known, wherein the temperature of the exhaust gas of the internal combustion engine is adjusted by a corresponding lambda control to ensure the necessary for the regeneration of the particulate filter temperature and a simultaneous presence of residual oxygen in the exhaust passage of the internal combustion engine. A disadvantage of such a method, however, is that it comes through the lean adjustment of the internal combustion engine to increase the nitrogen oxide emissions in the exhaust gas during the regeneration of the particulate filter.

From the WO 2015/169958 A1 a spark ignition internal combustion engine is known, in whose exhaust system, a particulate filter is arranged, wherein for the regeneration of the particulate filter, a multi-stage process is performed in order to reduce the ride comfort during the regeneration of the particulate filter as little as possible. For this purpose, a passive regeneration of the particulate filter in a coasting phase of the internal combustion engine is combined as a "mildest" measure with corresponding active measures for regeneration, wherein in a multi-stage process the measures are selected which are carried out with the least intervention in the ride comfort or the performance of the internal combustion engine can be. A disadvantage of such a method, however, is that even here comes in the active measures to a lean adjustment of the combustion air ratio of the internal combustion engine and an associated increase in nitrogen oxide emissions.

From the EP 1 210 509 B1 a method for controlling a combustion process of an internal combustion engine during the regeneration of a NOx storage catalyst is known, which is arranged in an exhaust passage of an internal combustion engine. In this case, an injection start for the fuel injection in a regeneration operation of the NOx storage catalyst is set earlier than in a lean operation and increases the injection pressure, wherein a necessary for the regeneration of the NOx storage catalyst substoichiometric engine operation substantially by reducing a volume flow of intake air and by an exhaust gas recirculation is set. The EP 1 210 509 B1 However, does not refer to the regeneration of a particulate filter, but deals only with the reduction of nitrogen oxide emissions during normal operation of the vehicle and in the regeneration of the NOx storage catalyst.

In addition, exhaust aftertreatment systems are known in which the temperature of the particulate filter is increased by engine measures, in particular by an adjustment of the ignition angle in the "late" direction until the Regeneration temperature of the particulate filter is reached, and the oxygen required for the oxidation of the retained particulate matter in the carbon black filter is supplied to the exhaust gas passage via a secondary air system. But this always requires a secondary air system, which significantly increases the cost of the internal combustion engine.

The invention is based on the object, in an exhaust system without secondary air system to allow at least substantially neutral emissions regeneration of the particulate filter and overcome the known from the prior art disadvantages.

• - Betreiben des Verbrennungsmotors in einem Normalbetrieb mit stöchiometrischem Verbrennungsluftverhältnis, wobei die bei der Verbrennung entstehenden Rußpartikel in der Abgasanlage durch den Partikelfilter oder den Vier-Wege-Katalysator zurückgehalten werden,
• - Ermitteln eines Beladungszustandes des Partikelfilters oder des Vier-Wege-Katalysators, wobei bei Überschreiten eines Schwellenwertes der Beladung des Partikelfilters oder des Vier-Wege-Katalysators eine Regeneration eingeleitet wird,
• - Verstellen des Verbrennungsluftverhältnisses des Verbrennungsmotors von einem stöchiometrischen Verbrennungsluftverhältnis auf ein überstöchiometrisches oder unterstöchiometrisches Verbrennungsluftverhältnis, um dem Partikelfilter oder dem Vier-Wege-Katalysator den zur Oxidation des zurückgehaltenen Rußes notwendigen Sauerstoff zuzuführen, wobei
• - der NOx-Speicherkatalysator während der Regeneration des Partikelfilters oder des Vier-Wege-Katalysators beladen oder regeneriert wird.

According to the invention, this object is achieved by a method for exhaust aftertreatment of an internal combustion engine in whose exhaust system a particle filter or a four-way catalytic converter is arranged, and in whose exhaust system upstream or downstream of the particle filter or the four-way catalytic converter a NOx storage catalytic converter is arranged. solved, comprising the following steps:

• Operating the internal combustion engine in a normal operation with a stoichiometric combustion air ratio, wherein the soot particles formed in the combustion are retained in the exhaust system by the particle filter or the four-way catalytic converter,
• Determining a loading state of the particulate filter or of the four-way catalytic converter, wherein regeneration is initiated when a threshold value of the loading of the particulate filter or the four-way catalytic converter is exceeded,
• Adjusting the combustion air ratio of the internal combustion engine from a stoichiometric combustion air ratio to a superstoichiometric or substoichiometric combustion air ratio to supply the particulate filter or the four-way catalyst with the oxygen necessary for oxidation of the retained soot;
• - The NOx storage catalyst is loaded or regenerated during the regeneration of the particulate filter or the four-way catalyst.

In such a method, it can also be ensured during the regeneration of the particulate filter that efficient exhaust gas purification is ensured and, in particular, there is no increase in nitrogen oxide emissions.

The features listed in the dependent claims advantageous improvements and developments of the method specified in the independent claim for the exhaust aftertreatment of an internal combustion engine are possible.

In a preferred embodiment of the invention, it is provided that the NOx storage catalyst is disposed in the exhaust system downstream of the particulate filter or the four-way catalytic converter, wherein occurring in a regeneration of the particulate filter in a lean operation of the internal combustion engine nitrogen oxides are stored in the NOx storage catalyst and the NOx storage catalyst is regenerated by a subsequent rich operation of the internal combustion engine. By arranging the NOx storage catalyst downstream of the particulate filter or the four-way catalyst, the nitrogen oxides occurring in a lean operation of the internal combustion engine for regenerating the four-way catalyst or the particulate filter can be removed from the exhaust gas and thus an increase in nitrogen oxide emissions downstream of the NOx storage catalyst can be prevented or reduced. The NOx storage catalytic converter can then be regenerated again in a later engine operation with a substoichiometric combustion air mixture without there being any increase in nitrogen oxide emissions in the regeneration of the NOx storage catalytic converter.

In a further preferred embodiment of the method is provided that the internal combustion engine for the regeneration of the particulate filter or the four-way catalyst with a superstoichiometric combustion air ratio λ _E between 1.01 and 1.20, more preferably between 1.07 and 1.09 operated becomes. By a regeneration of the particulate filter or four-way catalyst at a superstoichiometric combustion air ratio of the internal combustion engine from 1.01 to 1.20 on the one hand sufficient oxygen for the regeneration of the particulate filter or the four-way catalyst is provided, on the other hand, an uncontrolled Rußabbrand, which can lead to a thermal component damage prevented. Particularly preferred is a range between 1.07 and 1.09, since in this area a sufficiently high regeneration rate is achieved and, secondly, the heat released in the oxidation of the soot particles causes the temperature of the particulate filter or four-way catalyst remains substantially constant and there is neither a thermal damage to the exhaust gas component nor to a termination of the regeneration by a temperature drop below the regeneration temperature.

According to an alternative embodiment of the method it is provided that the NOx storage catalyst is arranged in the exhaust system upstream of the particulate filter or the four-way catalyst, wherein the internal combustion engine for regenerating the particulate filter or the four-way catalyst with one of a stoichiometric combustion air ratio deviating combustion air ratio is operated. By a Arrangement of the NOx storage catalyst upstream of the particulate filter is a regeneration of the particulate filter with correspondingly high exhaust gas temperatures possible both at a stoichiometric and at a superstoichiometric combustion air ratio of the internal combustion engine.

In a preferred embodiment of the method it is provided that the internal combustion engine is operated with a superstoichiometric combustion air ratio, wherein the nitrogen oxide emissions occurring in the superstoichiometric combustion are retained in the NOx storage catalytic converter and a superstoichiometric exhaust gas passes through the NOx storage catalytic converter to the particle filter or the Way catalyst to supply the oxygen necessary for the oxidation of the retained carbon black. By means of a superstoichiometric, lean combustion air ratio, direct regeneration of the particulate filter is possible, with the nitrogen oxide emissions occurring during the lean combustion being retained in the NOx storage catalyst.

Alternatively, it is advantageously provided that the internal combustion engine is operated with a substoichiometric combustion air ratio, wherein the NOx storage catalyst is regenerated and releases oxygen during its regeneration, with which the soot retained in the particle filter or in the four-way catalyst is oxidized. In a regeneration of the NOx storage catalyst in a phase of superstoichiometric engine operation, in addition to nitrogen dioxide (NO ₂ ) also molecular oxygen is released, which can be used to regenerate the retained in the particulate filter or four-way catalyst soot. The released nitrogen dioxide emissions with the unburned fuel constituents, in particular with the unburned hydrocarbons, can be converted into elemental nitrogen, water vapor and carbon dioxide.

In a further improvement of the method is provided that the exhaust gas temperature is raised for the regeneration of the particulate filter or the four-way catalyst by internal engine measures. For the regeneration of the particulate filter or the four-way catalyst, in addition to the presence of residual oxygen in the exhaust gas channel, a temperature necessary for the oxidation of the soot is necessary. If the exhaust gas temperature does not lead to this necessary component temperature of the particulate filter or four-way catalytic converter with an unchanged operation of the internal combustion engine, the exhaust gas temperature can be raised by internal engine measures to achieve the regeneration temperature.

It is preferred if the internal engine measures include an adjustment of the ignition angle in the "late" direction. By adjusting the ignition angle of the internal combustion engine in the direction of "late", an increase in the exhaust gas temperature can be achieved, while the efficiency of the internal combustion engine is deteriorated in parallel and the measure should remain limited to the period of regeneration. This adjustment in the direction of "late" not only leads to an increase in consumption, but can also lead to a reduction in the raw emissions of nitrogen oxides in an unexpected, advantageous manner.

Alternatively, it is provided that a first group of combustion chambers of the internal combustion engine with a superstoichiometric combustion air ratio and a second group of combustion chambers are operated with a substoichiometric combustion air ratio, wherein an exothermic reaction of the unburned fuel components in the exhaust system upstream of the particulate filter or the four-way catalyst takes place , This exothermic reaction of the unburned fuel components in the exhaust passage leads to an increase in the exhaust gas temperature, whereby the particulate filter or the four-way catalyst can be heated to its temperature necessary for regeneration. Alternatively, a heating of the particulate filter or the four-way catalyst by post-injection is possible.

According to the invention, a device for exhaust aftertreatment of an internal combustion engine with an exhaust system, in which a particulate filter or a four-way catalytic converter and a NOX storage catalytic converter are arranged, as well as with a control device with a machine-readable program code is achieved, wherein the control device in an execution of the program code to is set up to carry out a method according to the invention. By means of such an exhaust gas aftertreatment device, particularly efficient exhaust gas purification is also possible in operating phases, in particular during regeneration of the particulate filter, in which an increase in emissions may occur in exhaust systems known from the prior art.

In a preferred embodiment of the invention it is provided that the particle filter or the four-way catalyst is arranged close to the engine as the first component of the exhaust aftertreatment. By a close-coupled arrangement of the particulate filter or four-way catalyst, the regeneration temperature of at least 550 ° C can be achieved comparatively easily. Since the maximum storage capacity of NOx storage catalysts in a temperature range of about 250 ° C to 480 ° C, and thus below the regeneration temperature of the particulate filter or the four-way catalyst, It is advantageous if the hot exhaust gas first flows through the particle filter or four-way catalytic converter and then through the NOx catalytic converter in order to achieve optimum exhaust gas aftertreatment and the lowest possible emissions.

It is particularly preferred if a three-way catalytic converter is arranged between the particle filter or the four-way catalytic converter and the NOx storage catalytic converter. By means of an interposed three-way catalytic converter, in particular in an underfloor position of a motor vehicle, an efficient exhaust gas purification can be achieved, wherein the exhaust gas temperature is lowered before the NOx storage catalytic converter in order to achieve maximum performance of the NOx storage catalytic converter. In particular, such a three-way catalyst has a limited oxygen storage capacity in order to convert occurring during the regeneration of the particulate filter secondary emissions, in particular carbon monoxide.

In a further, preferred embodiment of the invention, it is provided that the NOx storage catalytic converter is arranged in the exhaust system upstream of the particle filter or the four-way catalytic converter. If the particle filter or the four-way catalyst is heated externally, the temperature of the particle filter can be increased substantially independently of the exhaust gas temperature of the internal combustion engine. Thus, even with such an arrangement for the NOx storage catalyst and for the particulate filter or four-way catalyst ideal thermal conditions can be achieved to allow the most efficient exhaust aftertreatment.

It is particularly preferred if the particle filter or the four-way catalyst is followed by a three-way catalyst. In addition to the known exhaust gas purification by the three-way catalyst during normal operation of the internal combustion engine, the arrangement of a three-way catalyst in the exhaust duct downstream of the particulate filter or the four-way catalyst can have further advantages. Depending on the residual oxygen content, the temperature and the pressure in the exhaust system, it is possible that the soot retained in the particulate filter or four-way catalyst is oxidized only incompletely and thereby secondary emissions of carbon monoxide occur. Through a three-way catalyst, these carbon monoxide emissions can be converted to carbon dioxide, thus reducing carbon monoxide emissions.

According to a further improvement of the invention, it is provided that the NOx storage catalytic converter and the particle filter or the NOx storage catalytic converter and the four-way catalytic converter are arranged close to the engine. By arranging both exhaust aftertreatment components close to the engine, both the NOx storage catalyst and the particle filter or the four-way catalyst can be brought to their ideal operating temperatures comparatively quickly so that internal engine measures for increasing the temperature are only necessary for a comparatively short time. As a result, the additional consumption during such a heating phase can be kept within narrow limits.

Further preferred embodiments of the invention will become apparent from the remaining, mentioned in the dependent claims characteristics.

The various embodiments of the invention mentioned in this application are, unless otherwise stated in the individual case, advantageously combinable with each other.

• 1 eine erfindungsgemäße Abgasanlage eines Verbrennungsmotors, mit der die Emissionen während der Regeneration des Partikelfilters in einem erfindungsgemäßen Verfahren reduziert werden können;
• 2 eine alternative Ausführungsform der erfindungsgemäßen Abgasanlage, bei der anstelle eines Partikelfilters motornah ein Vier-Wege-Katalysator angeordnet ist;
• 3 ein weiteres Ausführungsbeispiel einer erfindungsgemäßen Abgasanlage eines Verbrennungsmotors, mit der die Emissionen während der Regeneration des Partikelfilters in einem weiteren erfindungsgemäßen Verfahren reduziert werden können; und
• 4 ein alternatives Ausführungsbeispiel der in 3 dargestellten Abgasanlage, bei welcher der Partikelfilter durch einen Vier-Wege-Katalysator ersetzt ist.

The invention will be explained below in embodiments with reference to the accompanying drawings. Show it:

• 1 an exhaust system according to the invention of an internal combustion engine, with which the emissions during the regeneration of the particulate filter can be reduced in a method according to the invention;
• 2 an alternative embodiment of the exhaust system according to the invention, in which instead of a particulate filter close to the engine, a four-way catalyst is arranged;
• 3 a further embodiment of an exhaust system according to the invention of an internal combustion engine, with which the emissions during the regeneration of the particulate filter can be reduced in a further inventive method; and
• 4 an alternative embodiment of the in 3 illustrated exhaust system in which the particulate filter is replaced by a four-way catalyst.

1 shows a schematic representation of an internal combustion engine 10 with one at an outlet 32 of the internal combustion engine 10 connected exhaust system 12 , In the exhaust system 12 is in the flow direction of an exhaust gas of the internal combustion engine 10 through the exhaust system 12 close to the engine a particle filter 14 arranged. Under a near-engine position in this context is a position in the exhaust system with a distance of less than 80 cm, preferably less than 50 cm, exhaust run length of the outlet 32 of the internal combustion engine 10 to understand. Downstream of the particulate filter 14 , especially in a subfloor position of a motor vehicle, are a three Way catalyst 16 and further downstream, a NOx storage catalyst 18 disposed through an exhaust passage 20 the exhaust system 12 connected to each other. The amount of fuel injected into the combustion chambers of the internal combustion engine 10 and thus the combustion air ratio λ _E of the internal combustion engine 10 is via a control unit 24 controllable. For controlling the combustion air ratio λ _E of the internal combustion engine 10 are in the exhaust duct 20 several lambda sensors 26 . 28 . 30 arranged.

With essentially the same structure as 1 is described in the in 2 illustrated embodiment of the (uncoated) particulate filter 14 by a particle filter with a three-way catalytically active coating, a so-called four-way catalyst 22 replaced. The four-way catalyst 22 combines the functions of a particulate filter and a three-way catalytic converter. By the arrangement of the other three-way catalyst 16 in the underfloor position of the motor vehicle, the four-way catalyst can be made comparatively small to a rapid heating to an operating temperature after a cold start of the engine 10 to enable.

In operation of the internal combustion engine 10 become the particles occurring during the combustion in the exhaust gas of the internal combustion engine 10 through the particle filter 14 or the four-way catalyst 22 retained. In this case, by the Abschiebemechanismus the particulate filter 14 or the four-way catalyst 22 loaded with soot. As a result of the loading effects such as increased fuel consumption, power loss and misfire can occur when the exhaust back pressure due to the loading of the particulate filter 14 or the four-way catalyst 22 rises above a certain threshold. Consequently, the particulate filter needs 14 or the four-way catalyst 22 be regenerated cyclically or depending on the load. For regeneration of the particle filter 14 or the four-way catalyst 22 In addition to reaching a regeneration temperature, the presence of residual oxygen in the exhaust system is necessary in order to those in the particulate filter 14 or in the four-way catalyst 22 oxidize retained carbon black particles. Due to the superstoichiometric operation of the internal combustion engine 10 lose the three-way catalyst 16 and the four-way catalyst 22 Their conversion properties for nitrogen oxides, since no reducing agent for the reduction of nitrogen oxides to elemental nitrogen is no longer present.

The nitrogen oxides (NO _x ) occurring in this superstoichiometric operation are stored in the NO _x storage catalytic converter 18. Since the storage capacity of the NOx storage catalyst 18 is limited, this must also periodically by a substoichiometric operation of the engine 10 be regenerated.

In 3 an alternative embodiment of an exhaust aftertreatment device according to the invention is shown. In this case, a NOx storage catalytic converter 18 is the first component of the exhaust aftertreatment in an exhaust system 12 an internal combustion engine 10 arranged. Downstream of the NOx storage catalyst 18 are in the exhaust system 12 a particle filter 14 and further downstream, a three-way catalyst 16 arranged. For controlling the combustion air ratio λ _E of the internal combustion engine 10 are in the exhaust duct 20 the exhaust system 12 several lambda sensors 26 . 28 . 30 arranged.

In a lean operation of the internal combustion engine 10 can the regeneration of the particulate filter 14 necessary oxygen will be delivered. The occurring nitrogen oxide emissions are retained in the NOx storage catalytic converter 18, which contains barium oxide as storage medium for the nitrogen oxides, and stored as barium nitrates. The regeneration of the particle filter 14 is analogous to that 1 and 2 described process. During the regeneration of the NOx storage catalytic converter 18 with a substoichiometric combustion air ratio of the internal combustion engine 10 The barium nitrite is again reduced to barium oxide and the released nitrogen oxides can be reacted with the unburned hydrocarbons in the exhaust gas of the internal combustion engine, so that it downstream of the three-way catalyst 16 there is no increase in nitrogen oxide emissions. In the reduction of barium nitrite to barium oxide elemental oxygen and water vapor are released in addition to the nitrogen oxides, which for the regeneration of the particulate filter 14 can be used. Thus, a regeneration of the particulate filter 14 both at a superstoichiometric and at a stoichiometric combustion air ratio of the internal combustion engine 10 , and thus in more operating situations than in the 1 and 2 illustrated embodiments, possible, without increasing the NOx emissions. Thus, an exhaust-neutral regeneration of the particulate filter 14 in the exhaust system of a spark-ignited internal combustion engine 10 possible without an increase in nitrogen oxide emissions.

In 4 is a further embodiment of an exhaust aftertreatment device according to the invention shown. With essentially the same structure as 3 shown, is the particle filter 14 through a four-way catalyst 22 replaced and thus has an additional coating to convert the harmful exhaust gas components.

LIST OF REFERENCE NUMBERS

10

internal combustion engine

12

exhaust system

14

particulate Filter

16

Three-way catalytic converter

18

NOx storage catalytic converter

20

exhaust duct

22

Four-way catalyst

24

control unit

26

first lambda probe

28

second lambda probe

30

third lambda probe

32

outlet

λ _E

Combustion air ratio of the internal combustion engine

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102013220899 A1 [0003]
• WO 2015/169958 A1 [0004]
• EP 1210509 B1 [0005]

Claims (15)

A method for exhaust aftertreatment of an internal combustion engine (10), in the exhaust system (12) a particulate filter (14) or a four-way catalytic converter (22) is arranged, and in the exhaust system (12) upstream or downstream of the particulate filter (14) or Four-way catalytic converter (22) a NOx storage catalyst (18) is arranged, comprising the following steps: - Operating the internal combustion engine (10) in a normal operation with a stoichiometric combustion air ratio, wherein the resulting during combustion soot particles in the exhaust system (12) by the particulate filter (14) or the four-way catalyst (22) are retained, Determining a loading state of the particulate filter (14) or of the four-way catalytic converter (22), wherein regeneration is initiated when a threshold value of the loading of the particulate filter (14) or the four-way catalytic converter (22) is exceeded, - Adjusting the combustion air ratio of the internal combustion engine (10) from a stoichiometric combustion air ratio to a stoichiometric or stoichiometric combustion air ratio to the particulate filter (14) or the four-way catalyst (22) to supply the necessary oxygen for the oxidation of the retained soot, wherein - The NOx storage catalyst (18) during the regeneration of the particulate filter (14) or the four-way catalyst (22) is loaded or regenerated. Process for exhaust aftertreatment after Claim 1 , characterized in that the NOx storage catalyst (18) in the exhaust system (12) downstream of the particulate filter (14) or the four-way catalytic converter (22) is arranged, which in a regeneration of the particulate filter (14) in a lean operation of the internal combustion engine (10) occurring nitrogen oxides are stored in the NOx storage catalyst (18) and the NOx storage catalyst (18) is regenerated by a subsequent rich operation of the internal combustion engine (10). Process for exhaust aftertreatment after Claim 2 , characterized in that the internal combustion engine (10) for the regeneration of the particulate filter (14) or the four-way catalyst (22) with a superstoichiometric combustion air ratio λ _E between 1.03 and 1.20, more preferably between 1.07 and 1 , 09, is operated. Process for exhaust aftertreatment after Claim 1 characterized in that the NOx storage catalyst (18) is disposed in the exhaust system (12) upstream of the particulate filter (14) or the four-way catalyst (22), the internal combustion engine (10) for regenerating the particulate filter (14). or the four-way catalyst (22) is operated with a deviating from a stoichiometric combustion air ratio combustion air ratio. Process for exhaust aftertreatment after Claim 4 , characterized in that the internal combustion engine is operated with a superstoichiometric combustion air ratio, wherein the nitrogen oxide emissions occurring in the superstoichiometric combustion are retained in the NOx storage catalytic converter (18) and a superstoichiometric exhaust gas passes through the NOx storage catalytic converter (18) to the particle filter (14). or the four-way catalyst (22) to supply the oxygen necessary for the oxidation of the retained soot. Process for exhaust aftertreatment after Claim 4 , characterized in that the internal combustion engine is operated with a substoichiometric combustion air ratio, wherein the NOx storage catalyst (18) is regenerated and releases oxygen during its regeneration, with which in the particulate filter (14) or in the four-way catalyst (22) retained Soot is oxidized. Process for exhaust aftertreatment according to one of Claims 1 to 6 , characterized in that the exhaust gas temperature for the regeneration of the particulate filter (14) or the four-way catalyst (22) is raised by internal engine measures. Process for exhaust aftertreatment after Claim 7 , characterized in that the internal engine measures include an adjustment of the ignition angle in the "late" direction. Process for exhaust aftertreatment after Claim 7 characterized in that a first group of combustion chambers are operated with a superstoichiometric combustion air ratio and a second group of combustion chambers with a substoichiometric combustion air ratio, wherein an exothermic reaction of the unburned fuel components takes place in the exhaust system upstream of the particulate filter or the four-way catalyst. Device for the exhaust aftertreatment of an internal combustion engine (10) with an exhaust system (12), in which a particle filter (14) or a four-way catalytic converter (22) and a NOX storage catalytic converter (18) are arranged, as well as with a control device (24) with a machine-readable program code, which is set up when the program code is executed, a method according to one of Claims 1 to 9 perform. Device for exhaust aftertreatment after Claim 10 , characterized in that the particulate filter (14) or the four-way catalyst (22) is arranged close to the engine as a first component of the exhaust aftertreatment. Device for exhaust aftertreatment after Claim 11 , characterized in that between the particulate filter (14) or the four-way catalyst (22) and the NOx storage catalyst (18) a three-way catalyst (16) is arranged. Device for exhaust aftertreatment after Claim 10 , characterized in that the NOx storage catalyst (18) in the exhaust system (12) upstream of the particulate filter (14) or the four-way catalyst (22) is arranged. Device for exhaust aftertreatment after Claim 13 , characterized in that the particle filter (14) or the four-way catalyst (22) is followed by a three-way catalyst (16). Device for exhaust aftertreatment after Claim 13 or 14 , characterized in that the NOx storage catalytic converter (18) and the particulate filter (14) or the NOx storage catalytic converter (18) and the four-way catalytic converter (22) are arranged close to the engine.

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