DE102019108016B4 - Process for regenerating a particle filter - Google Patents

Abstract

Method for regenerating a particle filter (30) or a four-way catalytic converter (32) in an exhaust system (20) of an internal combustion engine (10), comprising the following steps: - regenerating the particle filter (30) or the four-way catalytic converter (32 ) in an unfired overrun mode of the internal combustion engine (10), in which no fuel is burned in a combustion chamber (12, 14, 16, 18) of the internal combustion engine (10), - oxidation in the particle filter (30) or in the four-way catalytic converter (32) retained soot particles in the overrun mode of the internal combustion engine (10), - determining a component temperature (TPF, TFWC) of the particle filter (30) or the four-way catalytic converter (32), - comparing the determined component temperature (TPF, TFWC) with a critical component limit temperature (Tcrit), - operating the internal combustion engine (10) in a partially fired operation when the critical component limit temperature (Tcrit) is exceeded or a gradient of the temperature rise of the component temperatures ture (TPF, TFWC) suggests that the critical component limit temperature (Tcrit) is exceeded, with at least one combustion chamber (12, 14, 16, 18) continuing to be operated without being fired, - oxidation of the particles in the particle filter (30) or in the four-way catalytic converter ( 32) retained soot particles in the partially fired operation of the internal combustion engine (10), with an over-stoichiometric exhaust gas/air ratio (λEG> 1) being set, which prevents a further rise in temperature in the particle filter (30) or in the four-way catalytic converter (32). or limited, wherein- an idling speed is increased in the part-fired operation of the internal combustion engine (10).

Description

The invention relates to a method for regenerating a particle filter in the exhaust system of an internal combustion engine, in particular an Otto engine, according to the preamble of the independent patent claim. The invention also relates to a motor vehicle with an Otto engine and a particle filter arranged in the exhaust system of the Otto engine for carrying out such a method.

The continuous tightening of the exhaust gas legislation places high demands on the vehicle manufacturers, which are solved by appropriate measures to reduce engine raw emissions and appropriate exhaust gas aftertreatment. With the introduction of the EU6 legislative stage, a limit value for a particle number is prescribed for petrol engines, which in many cases makes the use of a petrol particle filter necessary. Such an Otto particle filter is loaded with soot when driving. So that the exhaust back pressure does not increase too much, this Otto particle filter must be regenerated continuously or periodically. The increase in exhaust gas back pressure can lead to increased consumption by the combustion engine, loss of performance and an impairment of smooth running up to misfiring. In order to thermally oxidize the soot retained in the Otto particle filter with oxygen, a sufficiently high temperature level in conjunction with the oxygen present at the same time in the exhaust system of the Otto engine is necessary. Since modern Otto engines are normally operated with a stoichiometric combustion air ratio (λ=1) without excess oxygen, additional measures are required. In addition, possible measures include, for example, increasing the temperature by adjusting the ignition angle, temporarily leaning the gasoline engine, blowing secondary air into the exhaust system, or a combination of these measures. Up to now, retarding the ignition angle in combination with lean adjustment of the Otto engine has been preferred, since this method does not require any additional components and can supply a sufficient quantity of oxygen at most operating points of the Otto engine. Furthermore, the particle filter can be regenerated when the internal combustion engine is overrun. In the fuel cut-off phase, the injection of fuel into the combustion chambers of the combustion engine is deactivated and the combustion engine pumps fresh air and thus oxygen into the exhaust system. If the particle filter has a temperature of more than 500°C at this point, the soot particles retained in the particle filter are oxidized by the oxygen. This is called passive regeneration of the particulate filter.

In the phase of passive regeneration, the focus is on component protection. It is imperative to ensure that a component limit temperature for the particle filter is not exceeded in order to avoid thermal damage to the particle filter. As a result of the high oxygen content in the fresh air, the soot retained in the particle filter reacts exothermically with the oxygen and the temperature in the particle filter rises exponentially. In this case, the component limit temperature can be maintained by deactivating the fuel cutoff and injecting fuel into the combustion chambers of the internal combustion engine again. The combustion engine is operated stoichiometrically so that the exhaust gas does not contain any residual oxygen to oxidize the soot particles. However, this measure to protect components leads to increased consumption and possibly to a reduction in driving comfort.

From the DE 102 40 913 A1 a method for operating a diesel engine with a particle filter arranged in the exhaust system of the diesel engine is known, in which, in order to reach the burn-off temperature of the soot particles retained on the particle filter, the start of injection is gradually adapted to normal driving operation depending on the progress of regeneration and only then is it switched off a heat charge takes place when the particulate filter is fully regenerated.

From the DE 10 2012 022 153 A1 discloses a method for regenerating a particulate filter in the exhaust system of an Otto engine, in which a throttle device in the intake tract is opened in order to provide the oxygen necessary for regenerating the particulate filter. Alternatively, it is provided that the combustion air ratio is adjusted in the lean direction in order to provide the oxygen required for regeneration of the particle filter.

In addition, from the DE 10 2017 206 162 A1 discloses a device for controlling a diesel engine having a plurality of cylinders and a storage catalytic converter arranged in the exhaust system of the diesel engine. In order to reduce the emissions of pollutants, in particular nitrogen oxides, it is provided that the control unit checks whether regeneration of the storage catalytic converter is necessary and determines a catalytic converter temperature in the area of the storage catalytic converter. The temperature determined is compared with a threshold temperature and, if the temperature falls below the threshold, some of the cylinders are switched off and regeneration of the storage catalytic converter is then initiated.

the DE 10 2015 108 224 A1 discloses an exhaust aftertreatment system for a gasoline engine with a particle filter, regeneration of the particle filter being proposed when the internal combustion engine is overrun. The amount of exhaust gas recirculated via the low-pressure exhaust gas recirculation is regulated via an exhaust gas flap in order to control the oxygen content in the exhaust gas during an overrun phase of the internal combustion engine.

From the DE 10 2013 220 881 A1 a method for controlling the temperature of a particle filter of an exhaust gas aftertreatment system during a regeneration of the particle filter is known, which is arranged in an exhaust system of an internal combustion engine. The method has the following steps: measuring the temperature of the particle filter, detecting a loading condition of the particle filter, and setting a mass flow of air which flows through the particle filter, depending on the measured temperature and the detected loading condition of the particle filter. The mass flow of air is adjusted in such a way that the particle filter is cooled by the mass flow of air.

the DE 10 2016 101 105 A1 discloses a method for regenerating a particle filter in the exhaust system of an internal combustion engine. The particulate filter is regenerated during Deceleration Fuel Shut Off operating conditions (DFSO operating conditions). DFSO is a mode to improve fuel economy and reduce brake wear in motor vehicles with a powertrain that normally operates at stoichiometric conditions. With this approach, fuel injection to one or more cylinders is disabled during selected operating conditions to provide the oxygen needed to regenerate the particulate filter.

From the DE 603 11 758 T2 an exhaust aftertreatment system for an internal combustion engine with a particle filter is known. The idling speed of the internal combustion engine is increased during braking operation of the motor vehicle in order to enable a smooth transition from braking operation to idling operation.

A method for regenerating a particle filter in the exhaust system of an internal combustion engine in a motor vehicle is known from US 2017/0 051 652 A1. The procedure includes steps to protect the diesel particulate filter from overheating and premature aging. In this case, to control the particle filter temperature, a cylinder deactivation of the internal combustion engine or an engine speed of the internal combustion engine is controlled or regulated.

The disadvantage of the known solutions, however, is that the methods either relate to the regeneration of a diesel engine that is always operated with excess air and can therefore not be transferred to a stoichiometrically operated Otto engine, or the amount of boost air is limited in the known methods in order to avoid uncontrolled soot burn-off on the particle filter . The overrun air is throttled to such an extent that there are relatively long periods of time for the regeneration of the particle filter. In addition, the small amount of overrun air can lead to the temperature of the particle filter falling below the regeneration temperature required for the oxidation of the soot, so that the regeneration comes to a standstill and additional heating measures have to be initiated in order to heat the particle filter back to the regeneration temperature.

The object of the invention is to implement effective component protection for the particle filter and at the same time to enable continuous passive regeneration of the particle filter.

• - Regenerieren des Partikelfilters oder des Vier-Wege-Katalysators in einer ungefeuerten Schubphase des Verbrennungsmotors, in welcher kein Kraftstoff in den Brennräumen des Verbrennungsmotors verbrannt wird,
• - Oxidation der im Partikelfilter oder im Vier-Wege-Katalysator zurückgehaltenen Rußpartikel im Schubbetrieb des Verbrennungsmotors,
• - Ermitteln einer Bauteiltemperatur des Partikelfilters oder des Vier-Wege-Katalysators,
• - Vergleichen der ermittelten Bauteiltemperatur mit einer kritischen Bauteilgrenztemperatur,
• - Betreiben des Verbrennungsmotors in einem teilgefeuerten Betrieb, wenn die kritische Bauteilgrenztemperatur überschritten wird oder ein Gradient des Temperaturanstiegs der Bauteiltemperatur ein Überschreiten der kritischen Bauteilgrenztemperatur nahelegt, wobei mindestens ein Brennraum weiterhin ungefeuert betrieben wird,
• - Oxidation der im Partikelfilter oder im Vier-Wege-Katalysator zurückgehaltenen Rußpartikel im teilgefeuerten Betrieb des Verbrennungsmotors, wobei ein überstöchiometrisches Abgas-Luft-Verhältnis eingestellt wird, welches einen weiteren Temperaturanstieg im Partikelfilter oder im Vier-Wege-Katalysator verhindert oder begrenzt, wobei
• - eine Leerlaufdrehzahl in dem teilgefeuerten Betrieb des Verbrennungsmotors angehoben wird.

According to the invention, this object is achieved by a method for regenerating a particle filter or a four-way catalytic converter in the exhaust system of an internal combustion engine, which comprises the following steps:

• - Regeneration of the particle filter or the four-way catalytic converter in an unfired overrun phase of the internal combustion engine, in which no fuel is burned in the combustion chambers of the internal combustion engine,
• - Oxidation of the soot particles retained in the particulate filter or in the four-way catalytic converter when the combustion engine is overrun,
• - determining a component temperature of the particle filter or the four-way catalytic converter,
• - Comparing the determined component temperature with a critical component limit temperature,
• - Operating the internal combustion engine in a partially fired mode if the critical component limit temperature is exceeded or a gradient in the temperature rise of the component temperature suggests that the critical component limit temperature is exceeded, with at least one combustion chamber continuing to be operated unfired,
• - Oxidation of the soot particles retained in the particle filter or in the four-way catalytic converter in the partially fired operation of the internal combustion engine, with a super-stoichiometric exhaust gas/air ratio being set, which prevents or limits a further increase in temperature in the particulate filter or in the four-way catalytic converter, wherein
• - an idle speed is increased in the partially fired operation of the internal combustion engine.

In this context, a partially fired operation is to be understood as an operating state of the internal combustion engine in which fuel is injected into a first group of combustion chambers and this fuel is burned by ignition, while no fuel is injected into at least one combustion chamber and it consequently closes no heat is generated and no drive torque is transmitted from this cylinder to the crankshaft of the combustion engine.

A proposed method makes it possible to carry out passive regeneration of a particle filter or a four-way catalytic converter. The regeneration is not interrupted by the fact that the combustion engine is switched to normal stoichiometric operation to protect the component of the particle filter or four-way catalytic converter, but the combustion reaction can be maintained in overrun mode by switching the combustion engine from unfired overrun mode to partially fired operation with over-stoichiometric Exhaust gas is transferred. At the same time, the rise in temperature of the particulate filter or the four-way catalytic converter can be limited in such a way that thermal damage to the particulate filter or the four-way catalytic converter is prevented in an operationally reliable manner.

Advantageous improvements and further developments of the method for regenerating a particle filter specified in the independent claim are possible as a result of the features listed in the dependent claims.

In a preferred embodiment of the invention, it is provided that the fuel injection into the respective combustion chamber is switched off in unfired operation. By switching off the fuel injection, the respective combustion chamber can be switched to unfired operation. The intake and exhaust valves remain active, so that the respective cylinder compresses the fresh air and expels it into the exhaust system.

In an advantageous embodiment of the method, it is provided that the combustion chambers that are active in partially fired operation are operated with a stoichiometric combustion air ratio. The raw emissions in the respective combustion chamber can be minimized through stoichiometric operation. In addition, the remaining emissions can be easily converted by a three-way catalytic converter in the exhaust system, so that tailpipe emissions are minimized in partially fired operation.

Alternatively, it is advantageously provided that the combustion chambers that are active in partially fired operation are operated with a sub-stoichiometric combustion air ratio. A sub-stoichiometric air/fuel ratio means that unburned hydrocarbons and carbon monoxide get into the exhaust system of the combustion engine. These can be used on the three-way catalytic converter to reduce nitrogen oxides. However, a sub-stoichiometric combustion air ratio leads to exothermic conversion of the unburned or partially burned exhaust gas components, which can lead to a further increase in temperature in the exhaust system.

In a preferred embodiment of the method, it is provided that the exhaust gas/air ratio is regulated by the combustion air ratio in the combustion chambers that are active in partially fired operation. The exhaust air ratio can be controlled in a simple manner by the combustion air ratio in the active combustion chambers. This ensures that the exhaust gas does not contain too much oxygen, preventing uncontrolled soot burning off the particle filter.

It is particularly preferred if an exhaust gas/air ratio of 1.02<λ _EG <1.2 is set in partially fired operation. A sufficient excess of oxygen is provided in this area to achieve a sufficiently high rate of soot burn-off on the particle filter or the four-way catalytic converter for rapid regeneration and at the same time ensure that the critical component limit temperature is not exceeded by uncontrolled soot burn-off.

In an advantageous embodiment of the method, it is provided that the component limit temperature is in the range between 850°C and 950°C. Above this temperature range, premature aging or thermal damage to the particulate filter or the four-way catalytic converter is to be expected. It is therefore expedient to limit the temperature of the particle filter or the four-way catalytic converter to this upper limit temperature.

According to the invention it is provided that the idling speed of the internal combustion engine is increased in the partially fired operation of the internal combustion engine. This has the positive side effect that partially fired operation does not lead to uneven engine running and the associated loss of comfort. Furthermore, the acoustic behavior of the combustion engine is improved and "rumbling noises" are avoided.

In a preferred embodiment of the method, it is provided that the boost air quantity is adjusted by changing the position of a throttle valve in the intake tract of the internal combustion engine or by adjusting the opening times of the valves of the internal combustion engine. By changing the position of the throttle valve or extending the opening times of the valves, the amount of boost air can be adjusted in a correspondingly simple manner using existing components of the intake tract or of the internal combustion engine. No additional components are therefore necessary, as a result of which the method according to the invention can be carried out essentially cost-neutrally.

In this context, it is particularly preferred if the throttle flap is opened so far in overrun mode that maximum soot conversion on the particle filter or the four-way catalytic converter is achieved. In order to increase the soot conversion when the combustion engine is overrun, the throttle valve is opened, which increases the amount of air that is fed into the exhaust system via the combustion chambers. As a result, more fresh air is made available for oxidizing the soot retained in the particle filter, which speeds up the regeneration of the particle filter. Furthermore, the temperature of the particle filter increases with the conversion rate of the soot, so that internal engine heating measures or external heating can be dispensed with. Alternatively, the heating output can be reduced accordingly.

In an advantageous further development of the method, provision is made for the ignition in the active combustion chambers to be adjusted in the “advance” direction in partially fired operation in order to minimize additional heating of the exhaust gas flow. Adjusting the ignition point with the same amount of fuel tends to result in a lower exhaust gas temperature and thus less heat input into the exhaust system. This can further reduce the risk of exceeding the critical component limit temperature during passive regeneration of the particle filter or the four-way catalytic converter. Due to the earlier ignition timing, the exhaust gas temperature is lowered in partially fired operation.

In a preferred embodiment of the method, it is provided that the partially fired operation is started a maximum of 7 seconds, preferably a maximum of 5 seconds, after the start of the overrun operation. The oxygen input into the exhaust system of the internal combustion engine can be limited by a corresponding time limit of the unfired overrun operation. This ensures that the critical component limit temperature is not exceeded and there is no thermal damage to the particulate filter or the four-way catalytic converter.

According to the invention, a motor vehicle with an internal combustion engine is proposed, the outlet of which is connected to an exhaust system, a particle filter or a four-way catalytic converter being arranged in the exhaust system, the internal combustion engine being connected to an engine control unit which is set up to carry out a method according to the invention when a machine-readable program code is executed by the engine control unit. In such a motor vehicle it is possible to carry out a method according to the invention for regenerating the particle filter in an overrun phase of the internal combustion engine in order to achieve efficient and effective regeneration of the particle filter. In this way, both the regeneration time of the particulate filter can be reduced and the additional consumption for regenerating the particulate filter can be minimized

In a preferred embodiment of the invention, the internal combustion engine is designed as a four-cylinder engine, with three combustion chambers being fired and one combustion chamber being operated unfired in the partially fired mode. In a four-cylinder engine, an over-stoichiometric exhaust gas with a slight excess of oxygen can be achieved in a simple manner if three combustion chambers are fired and one combustion chamber is operated unfired in part-fired operation. The three fired combustion chambers are preferably operated with a stoichiometric combustion air ratio or a slightly sub-stoichiometric combustion air ratio in order to minimize the raw emissions of the internal combustion engine and to enable efficient exhaust gas aftertreatment.

Unless stated otherwise in the individual case, the various embodiments of the invention mentioned in this application can advantageously be combined with one another.

• 1 ein Kraftfahrzeug mit einem Verbrennungsmotor, in dessen Abgasanlage ein Partikelfilter oder ein Vier-Wege-Katalysator angeordnet ist, bei welchem ein erfindungsgemäßes Verfahren zur Regeneration des Partikelfilters durchgeführt werden kann; und
• 2 ein Ablaufdiagramm zur Durchführung eines erfindungsgemäßen Verfahrens zur Regeneration eines Partikelfilters oder eines Vier-Wege-Katalysators in der Abgasanlage eines Verbrennungsmotors.

The invention is explained below in exemplary embodiments with reference to the associated drawings. Identical components or components with the same function are identified with the same reference numbers. Show it:

• 1 a motor vehicle with an internal combustion engine, in whose exhaust system a Parti kelfilter or a four-way catalyst is arranged, in which an inventive method for regenerating the particle filter can be carried out; and
• 2 a flowchart for carrying out a method according to the invention for regenerating a particle filter or a four-way catalytic converter in the exhaust system of an internal combustion engine.

1 shows a schematic representation of a motor vehicle 100 which is driven by an internal combustion engine 10 . Internal combustion engine 10 is designed as a direct-injection Otto engine and includes a plurality of combustion chambers 12, 14, 16, 18, in which a fuel-air mixture is burned. The internal combustion engine 10 is preferably as in 1 shown as a spark-ignited internal combustion engine designed according to the Otto principle by means of spark plugs 44 . For this purpose, at least one spark plug 44 is arranged on each of the combustion chambers 12, 14, 16, 18 in order to ignite the fuel-air mixture. A fuel injector 46 is arranged on each of the combustion chambers 12, 14, 16, 18 in order to introduce a combustible fuel into the combustion chambers 12, 14, 16, 18. Furthermore, the combustion chambers 12, 14, 16, 18 each have at least one inlet valve 40 and one outlet valve 42, with which the gas exchange of the combustion chambers 12, 14, 16, 18 can be controlled. The intake valves 40 and the exhaust valves 42 can be actuated in a known manner via a corresponding mechanism by a camshaft of the internal combustion engine 10, which in 1 is not shown for reasons of clarity. The internal combustion engine 10 is connected to an air supply system 50 via an intake. The air supply system 50 comprises an intake duct 52 in which an air filter 54, downstream of the air filter 54 a compressor 58 of an exhaust gas turbocharger 24 and downstream of the compressor 58 a throttle valve 56 are arranged in the flow direction of the fresh air through the intake duct 52. Alternatively, the internal combustion engine 10 can also be designed as a naturally aspirated engine, in which case the exhaust gas turbocharger 24 and thus the compressor 58 in the intake passage 52 are omitted. Furthermore, the internal combustion engine 10 can be charged via a mechanical compressor or an electric compressor.

The internal combustion engine 10 is connected to an exhaust system 30 by its outlet 48 . The exhaust system 30 comprises, in the flow direction of an exhaust gas from the internal combustion engine 10 through an exhaust gas duct 22 of the exhaust system 20, a turbine 26 of the exhaust gas turbocharger 24, which drives the compressor 58 in the intake duct 52 via a shaft. A three-way catalytic converter 28 is arranged downstream of the turbine 26 and a particle filter 30 further downstream. Alternatively, the particle filter 30 can also be designed as a so-called four-way catalytic converter 32 with a three-way catalytically active coating. A first lambda probe 34, preferably a broadband probe, is arranged in the exhaust gas duct 22 downstream of the turbine 26 and upstream of the three-way catalytic converter 28 in order to determine the combustion air ratio in the exhaust gas. A second lambda probe 36 is provided in the exhaust gas duct 22 downstream of the three-way catalytic converter 28 and upstream of the particle filter 30 and can be designed as a jump probe or as a broadband probe. Furthermore, a temperature sensor 38 is provided in the exhaust system, preferably on the particle filter 30, with which an exhaust gas temperature before entry into the particle filter 30 can be determined and on the basis of this a temperature of the particle filter 30 can be calculated. Furthermore, a first pressure sensor 62 is provided upstream of the particle filter 30 and a second pressure sensor 64 is provided downstream of the particle filter 30, with which a differential pressure across the particle filter 30 is determined. Since the pressure difference across the particle filter 30 increases with increasing loading of the particle filter 30, the loading state of the particle filter 30 can be estimated on the basis of this pressure difference and it can be determined when regeneration of the particle filter 30 is necessary. Alternatively, the loading of the particle filter 30 can also be determined using a loading model, which uses the engine parameters of the internal combustion engine 10 to calculate a soot entry into the particle filter 30 or a soot discharge from the particle filter 30 and thus calculates the loading of the particle filter 30.

Internal combustion engine 10 is connected to an engine control unit 60 . Engine control unit 60 controls the injection quantities and the injection point in time of fuel injectors 46 for injecting the fuel into combustion chambers 12, 14, 16, 18 of internal combustion engine 10 and the position of throttle valve 56 in intake port 52. Engine control unit 60 is also connected to lambda sensors 34 via signal lines , 36, the temperature sensor 38 and the sensors 62, 64 for measuring the differential pressure via the particle filter 30.

As an alternative to a three-way catalytic converter 28 with a particle filter 30 downstream in the direction of flow, the particle filter 30 can also be designed as a so-called four-way catalytic converter 32 with a catalytically active coating. In this case, an additional three-way catalytic converter 28 can be omitted. Alternatively, a further three-way catalytic converter 28 can also be arranged upstream of the four-way catalytic converter 32, in which case a small-volume further three-way catalytic converter 28 is provided which quickly heats up to its operating temperature after a cold start of the internal combustion engine 10 and can thus promptly ensure efficient conversion of the pollutants in the exhaust gas after a cold start of the internal combustion engine 10 .

In 2 a flowchart for carrying out a method according to the invention for regenerating the particle filter 30 or a four-way catalytic converter 32 is shown. In a first method step <100>, the particle filter 30 or the four-way catalytic converter 32 is loaded with soot particles when the internal combustion engine 10 is in normal operation. In a method step <110>, internal combustion engine 10 is towed by a drive train of motor vehicle 100 . In this case, fuel injection into the combustion chambers 12, 14, 16, 18 of the internal combustion engine 10 is switched off, so that the internal combustion engine pumps the fresh air into the exhaust system 20 in this unfired overrun mode. With the oxygen contained in the fresh air, the soot particles retained in the particle filter 30 or four-way catalytic converter 32 are oxidized in a method step <120> in this unfired overrun mode. Due to the high amount of oxygen in the exhaust gas, the soot particles are burned off more quickly, as a result of which the temperature of the particle filter 30 or the four-way catalytic converter 32 rises. In a method step <130>, the component temperature T _PF , T _FWC of the particle filter 30 or the four-way catalytic converter 32 is determined. In a method step <140>, this component temperature is compared with a critical component limit temperature Tcrit, in a method step if the critical component limit temperature Tcrit is exceeded or if the temperature rise gradient of the component temperature T _PF , T _FWC , which suggests that the critical component limit temperature Tcrit is exceeded <150> the internal combustion engine 10 is operated in a partially fired mode, in which at least one combustion chamber 12, 14, 16, 18 continues to be operated unfired, i.e. without fuel injection into the unfired combustion chamber 12, 14, 16, 18. In a method step <160>, the soot retained in the particle filter 30 or in the four-way catalytic converter 32 is oxidized in the partially fired operation of the internal combustion engine 10, with a super-stoichiometric exhaust gas/air ratio λ _EG >1 being set in order to prevent a further temperature increase in the component temperature T _PF of the particulate filter 30 or the component temperature T _FWC of the four-way catalytic converter 32 to prevent or limit such that thermal damage to the particulate filter 30 or the four-way catalytic converter 32 is reliably prevented. As a result of the partially fired operation, the excess oxygen in the exhaust gas stream of the internal combustion engine 10 is reduced in such a way that the burning rate of the soot particles on the particle filter 30 or the four-way catalytic converter 32 slows down. As a result, a further increase in temperature is prevented or at least greatly restricted. The combustion air ratio λ _E of the combustion chambers 12, 14, 16 operated in a fired manner can be adjusted accordingly in order to achieve the fastest possible regeneration of the particle filter 30 or the four-way catalytic converter 32. Furthermore, during idling operation of internal combustion engine 10, the idling speed can be increased in order to reduce the loss of comfort due to rough running of internal combustion engine 10 in partially fired operation. In addition, the ignition timing in the fired combustion chambers 12, 14, 16 can be adjusted and, in particular, shifted in the “advanced” direction in order to minimize engine heat development and thus keep the heat input into the exhaust system 20 as low as possible. Furthermore, in the partially fired operation, the throttle valve 66 can be closed in order to minimize the air throughput through the combustion chambers 12, 14, 16, 18 and thus to minimize the fuel quantity required for stoichiometric or sub-stoichiometric operation of the fired combustion chambers 12, 14, 16. As a result, the fuel consumption in the partially fired operation of the internal combustion engine 10 can be minimized, as a result of which the additional consumption for the regeneration of the particle filter 30 or the four-way catalytic converter 32 can be minimized.

If the regeneration of the particle filter 30 or the four-way catalytic converter 32 is complete, the internal combustion engine 10 is again operated in a method step <170> in normal operation, in which all the combustion chambers 12, 14, 16, 18 operate in a fired operating state.

reference list

10

combustion engine

12

combustion chamber

14

combustion chamber

16

combustion chamber

18

combustion chamber

20

exhaust system

22

exhaust duct

24

exhaust gas turbocharger

26

turbine

28

Three-way catalytic converter

30

particle filter

32

Four-way catalytic converter

34

first lambda probe

36

second lambda probe

38

temperature sensor

40

intake valve

42

outlet valve

44

spark plug

46

fuel injector

48

outlet

50

air supply system

52

intake duct

54

air filter

56

throttle

58

compressor

60

control unit

100

motor vehicle

Claims (13)

Method for regenerating a particle filter (30) or a four-way catalytic converter (32) in an exhaust system (20) of an internal combustion engine (10), comprising the following steps: - regenerating the particle filter (30) or the four-way catalytic converter (32 ) in an unfired overrun mode of the internal combustion engine (10), in which no fuel is burned in a combustion chamber (12, 14, 16, 18) of the internal combustion engine (10), - oxidation in the particle filter (30) or in the four-way catalytic converter (32) retained soot particles in the overrun mode of the internal combustion engine (10), - determining a component temperature (T _PF , T _FWC ) of the particle filter (30) or the four-way catalytic converter (32), - comparing the determined component temperature (T _PF , T _FWC ) with a critical component limit temperature (T _crit ), - operating the internal combustion engine (10) in a partially fired operation when the critical component limit temperature (T _crit ) is exceeded or a gradient of the temperature rise d he component temperature (T _PF , T _FWC ) suggests that the critical component limit temperature (T _crit ) is exceeded, with at least one combustion chamber (12, 14, 16, 18) continuing to be operated unfired, - oxidation of the particles in the particle filter (30) or in the four- Way catalytic converter (32) retained soot particles in the partially fired operation of the internal combustion engine (10), wherein a super-stoichiometric exhaust gas-air ratio (λ _EG > 1) is set, which further increases the temperature in the particle filter (30) or in the four-way Catalyst (32) prevents or limits, wherein - an idling speed in the part-fired operation of the internal combustion engine (10) is increased. Method for regenerating a particle filter (30) or a four-way catalytic converter (32). claim 1 , characterized in that in non-fired operation fuel injection into the respective combustion chamber (12, 14, 16, 18) is switched off. Method for regenerating a particle filter (30) or a four-way catalytic converter (32). claim 1 or 2 , characterized in that the combustion chambers (12, 14, 16, 18) active in partially fired operation are operated with a stoichiometric combustion air ratio (λ _E = 1). Method for regenerating a particle filter (30) or a four-way catalytic converter (32). claim 1 or 2 , characterized in that the combustion chambers (12, 14, 16, 18) active in partially fired operation are operated with a sub-stoichiometric combustion air ratio (λ _E <1). Method for regenerating a particle filter (30) or a four-way catalytic converter (32) according to one of Claims 1 until 4 , characterized in that the exhaust gas/air ratio (λ _EG ) is regulated by the combustion air ratio (λ _E ) in the combustion chambers (12, 14, 16, 18) that are active in partially fired operation. Method for regenerating a particle filter (30) or a four-way catalytic converter (32) according to one of Claims 1 until 5 , characterized in that in partially fired operation an exhaust gas/air ratio (λ _EG ) of 1.02<λ _EG <1.2 is set. Method for regenerating a particle filter (30) or a four-way catalytic converter (32) according to one of Claims 1 until 6 , characterized in that the component limit temperature (T _crit ) is in the range between 850°C and 950°C. Method for regenerating a particle filter (30) or a four-way catalytic converter (32) according to one of Claims 1 until 7 , characterized in that a boost air quantity is adjusted by changing the position of a throttle valve in an intake tract of the internal combustion engine (10) or by adjusting the opening times of valves (40, 42) of the internal combustion engine (10). Method for regenerating a particle filter (30) or a four-way catalytic converter (32). claim 8 , characterized in that the throttle valve is opened so far in overrun that a maximum soot conversion on the Parti kelfilter (30) or the four-way catalyst (42) is achieved. Method for regenerating a particle filter (30) or a four-way catalytic converter (32) according to one of Claims 1 until 9 , characterized in that in partially fired operation, ignition in the active combustion chambers (12, 14, 16, 18) is adjusted in the “advanced” direction in order to minimize additional heating of an exhaust gas flow. Method for regenerating a particle filter (30) or a four-way catalytic converter (32) according to one of Claims 1 until 10 , characterized in that the partially fired operation is taken up a maximum of seven seconds after the start of the overrun operation. Motor vehicle (100) with an internal combustion engine (10) whose outlet (48) is connected to an exhaust system (20), a particle filter (30) or a four-way catalytic converter (32) being arranged in the exhaust system (20). is, and with an engine control unit (60), which is adapted to a method according to one of Claims 1 until 11 to be carried out when a machine-readable program code is executed by the engine control unit (60). Motor vehicle (100) according to claim 12 , characterized in that the internal combustion engine (10) is designed as a four-cylinder engine, with three combustion chambers (12, 14, 16) being fired in the partially fired operation and one combustion chamber (18) being operated unfired.

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