DE102020100564A1 - Process for exhaust aftertreatment of an internal combustion engine and internal combustion engine - Google Patents

Abstract

The invention relates to a method for exhaust gas aftertreatment of an internal combustion engine (10) with at least one combustion chamber (12). The internal combustion engine (10) is connected via its outlet (18) to an exhaust system (20) in which, in the flow direction of an exhaust gas flow from the internal combustion engine (10), there is an electrically heatable catalyst (26) and at least one further downstream of the electrically heatable catalyst (26) Catalyst (28, 30, 40) are arranged. It is provided that a temperature (TKAT) of a catalyst (28, 30, 40) is determined or calculated, this temperature (TKAT) being compared with a first threshold temperature (Ts1) . The electrically heatable catalytic converter (26) is activated when the calculated or determined temperature (TKAT) is below the first threshold temperature (Ts1). The temperature (TKAT) is compared with a second threshold temperature (Ts2), the electrically heated catalytic converter (26) being deactivated when the calculated or determined temperature (TKAT) is above the second threshold temperature (Ts2). The invention also relates to an internal combustion engine (10) to carry out such a procedure.

Description

The invention relates to a method for exhaust gas aftertreatment of an internal combustion engine and an internal combustion engine with an exhaust gas aftertreatment system for carrying out such a method according to the preamble of the independent claims.

The current exhaust gas legislation, and one that will become ever more stringent in the future, place high demands on the engine-related raw emissions and the exhaust gas aftertreatment of internal combustion engines. The demands for a further reduction in consumption and the further tightening of the exhaust gas standards with regard to the permissible nitrogen oxide emissions pose challenges for the engine developers. In gasoline engines, exhaust gas cleaning is carried out in the known manner via a three-way catalytic converter and a three-way catalytic converter. and downstream further catalytic converters. Exhaust gas aftertreatment systems are currently used in diesel engines, which have an oxidation catalytic converter or a NOx storage catalytic converter, a catalytic converter for the selective catalytic reduction of nitrogen oxides (SCR catalytic converter) and a particle filter for separating soot particles and possibly other catalytic converters. In order to meet the high requirements for minimal nitrogen oxide emissions, exhaust gas aftertreatment systems are known which have two SCR catalytic converters connected in series, each of the SCR catalytic converters being preceded by a metering element for metering in a reducing agent. A synthetic, aqueous urea solution is preferably used as the reducing agent, which is mixed with the hot exhaust gas flow in a mixing device upstream of the SCR catalytic converter. As a result of this mixing, the aqueous urea solution is heated, which releases ammonia in the exhaust gas duct. A commercially available, aqueous urea solution generally consists of 32.5% urea and 67.5% water.

With the introduction of legislative stage EU6, a limit value for the number of particles is prescribed for gasoline engines, which in many cases makes the use of a gasoline particle filter necessary. Such soot particles arise particularly after a cold start of the internal combustion engine due to incomplete combustion in combination with a substoichiometric combustion air ratio and cold cylinder walls during the cold start. The cold start phase is therefore decisive for compliance with the statutory particle limit values. Such a gasoline particulate filter continues to be loaded with soot while driving. This gasoline particulate filter must be regenerated continuously or periodically so that the exhaust gas back pressure does not increase too much. The increase in the exhaust gas back pressure can lead to increased consumption of the internal combustion engine, a loss of power and an impairment of the smoothness of running up to misfires. 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 connection with the simultaneous presence of oxygen in the exhaust system of the Otto engine is necessary. Since modern gasoline engines are normally operated with a stoichiometric combustion air ratio (A = 1) without excess oxygen, additional measures are required. In addition, possible measures include, for example, a temperature increase through an ignition angle adjustment, a temporary lean adjustment of the gasoline engine, the injection of secondary air into the exhaust system, or a combination of these measures. Up to now, an ignition angle adjustment in the late direction in combination with a lean adjustment of the gasoline engine has been preferred, since this method manages without additional components and can supply a sufficient amount of oxygen at most operating points of the gasoline engine.

Furthermore, electrically heatable catalytic converters are known from the prior art, with which heat can be introduced into the exhaust system essentially independently of the operation of the internal combustion engine in order to heat one or more exhaust gas aftertreatment components to their operating temperature.

From US 2014/0 366 509 A1 a method for operating an exhaust gas aftertreatment device with an electrical heating element for heating up an exhaust gas flow of the internal combustion engine or a surface of the exhaust gas aftertreatment device is known. An additive is introduced into the exhaust system at a metering point in such a way that it strikes the electrical heating element in order to improve the evaporation of the additive. An operating state in which deposits can form on the electrical heating element is identified on the basis of at least one operating variable. Depending on this operating state, a clock frequency of the electrically heatable catalytic converter is set, with deposits on the electrically heatable catalytic converter being avoided by a clocked activation and deactivation of the electric heating element at a set clock frequency.

The invention is now based on the object of keeping the exhaust gas aftertreatment components permanently at a temperature level at which an efficient conversion of the pollutants in the exhaust gas flow of the internal combustion engine is possible and to improve the energy efficiency of the exhaust gas aftertreatment system.

According to the invention, this object is achieved by a method for exhaust gas aftertreatment of an internal combustion engine with at least one combustion chamber. The internal combustion engine is connected via its outlet to an exhaust system in which an electrically heatable catalytic converter is arranged in the flow direction of an exhaust gas flow of the internal combustion engine and at least one further catalytic converter is arranged downstream of the electrically heatable catalytic converter. It is provided that a temperature of a catalytic converter is determined or calculated, this temperature being compared with a first threshold temperature. The electrically heated catalytic converter is activated when the calculated or determined temperature is below the first threshold temperature. The temperature is compared with a second threshold temperature, the electrically heatable catalytic converter being deactivated if the calculated or ascertained temperature is above the second threshold temperature. This enables particularly energy-efficient operation of the electrically heated catalytic converter in the manner of a two-point controller, which means that the exhaust system is only heated electrically when the temperatures of the exhaust gas aftertreatment components are too low to ensure efficient conversion of the pollutants in the exhaust gas flow Not enough heat is introduced into the exhaust system via the exhaust gas flow of the internal combustion engine to heat the exhaust gas aftertreatment components to their operating temperature. As a result, the period in which the electrically heatable catalytic converter is activated can be minimized, whereby the consumption of the internal combustion engine can be minimized. In addition, it can be ensured in all operating states that these pollutants are efficiently converted. After a cold start of the internal combustion engine or after a low-load operation, the exhaust gas aftertreatment components are heated in parallel by the exhaust gas flow of the internal combustion engine and by the electrically heated catalytic converter, whereby they reach their light-off temperature in a short time, from which an efficient conversion of pollutants by the respective Catalyst is possible.

The features listed in the dependent claims allow advantageous improvements and non-trivial further developments of the method for exhaust gas aftertreatment of an internal combustion engine specified in the independent claim.

In a preferred embodiment of the invention it is provided that the transfer behavior of the heat transfer from the electrically heatable catalyst to the catalyst following in the flow direction is modeled. As a result, the operation of the electrically heatable catalytic converter can be further optimized, since the dead time between a heat input from the electrically heatable catalytic converter and an actual temperature increase at a catalytic converter downstream in the flow direction can be taken into account in the heating strategy. In particular, if the catalytic converter threatens to cool down, the electrically heatable catalytic converter can be switched on in good time before the temperature of the catalytic converter falls below its light-off temperature. At low loads on the internal combustion engine or in overrun mode, the exhaust gas can be colder than the light-off temperature of the respective catalytic converter or another operating temperature of an exhaust gas aftertreatment component. Despite active operation of the internal combustion engine, the exhaust gas aftertreatment components would cool down in this operating state, so that efficient conversion of the pollutants in the exhaust gas flow would no longer be guaranteed. By modeling the heat transfer from the electrically heatable catalytic converter to the subsequent catalytic converter, the first threshold value, from which the electrically heatable catalytic converter is switched on, can be selected with a short distance from the respective light-off temperature, so that the operating time of the electrically heatable catalytic converter continues can be minimized.

In a further preferred embodiment of the invention it is provided that a catalytic converter is heated by the electrically heatable catalytic converter as a function of the expected temperature of a catalytic converter in the exhaust system. If an increase in the catalytic converter temperature is to be expected due to high-load operation of the internal combustion engine, the heating power of the electrically heatable catalytic converter can be reduced or the heating element of the electrically heatable catalytic converter can be switched off, since an increase in the catalytic converter temperature is to be expected in such an operating state. However, if the catalyst temperature is expected to drop due to overrun operation or a low-load phase, the electrically heatable catalyst is switched on in order to prevent the catalyst from cooling down below its light-off temperature.

In a further improvement of the method it is provided that the calculated or determined temperature of the catalyst or the expected temperature of the catalyst is multiplied or added by an offset factor in order to avoid an error in the determination of the calculated or determined temperature of the catalyst and / or the expected temperature Compensate for the temperature of the catalyst.

The statistically more uncertain / error-prone the temperature to be expected, for example because a longer cooling phase precedes the calculation of the temperature, the greater the offset factor elected. The temperature to be expected results as a clear solution of a calculation model to which a corresponding offset factor is assigned due to uncertainties and error deviations. The measured temperature is also subject to an uncertainty due to measurement errors, which can alternatively or additionally be compensated by the offset factor. The switch-on threshold for activating the electrically heatable catalytic converter is formed from the calculated target temperature and the offset factor, which can be linked additively or multiplicatively to the expected temperature. This ensures that an effective and efficient exhaust gas aftertreatment of the exhaust gas flow of the internal combustion engine is always possible even if there is a model deviation.

In an advantageous embodiment of the method, it is provided that the electrically heatable catalytic converter is operated for a defined time interval. A heating mode with defined heating intervals leads to a different oscillation of the temperature of the catalytic converters. In this way, the operation of the electrically heatable catalytic converter can take place at least partially decoupled in time from the current temperature or the heating or cooling behavior of the respective catalytic converter. This is advantageous because the electrically heatable catalytic converter can be operated at operating points of the internal combustion engine that are favorable in terms of consumption, emissions, acoustics or driving comfort. The electrically heatable catalytic converter can also be operated in particularly favorable driving situations.

In a preferred embodiment of the invention it is provided that the internal combustion engine is coupled to a generator, the electrical energy for heating the electrically heatable catalyst being provided by the generator. A load point of the internal combustion engine can be shifted by the generator at low engine loads, so that the risk of the catalytic converters cooling down below their respective light-off temperature is minimized. In addition, a battery that is actively connected to the generator is relieved, so that even when the battery is in a low state of charge, the electrically heated catalytic converter can be heated electrically without impairing its function.

In an advantageous embodiment of the method for exhaust gas aftertreatment, it is provided that the electrically heatable catalytic converter is heated up in overrun mode of the internal combustion engine. In an overrun mode, energy can be recuperated by the generator. This energy can be used to heat up the electrically heatable catalytic converter, so that precisely this energy is used efficiently to keep the exhaust gas aftertreatment components, in particular the catalytic converters, at their respective operating temperature.

In a preferred embodiment of the invention it is provided that the electrically heatable catalytic converter is activated as a function of the position of an exhaust gas aftertreatment component arranged downstream of the electrically heatable catalytic converter in the exhaust system. The electrically heatable catalytic converter can thus be used, for example, to keep an SCR catalytic converter in the temperature range required for the efficient conversion of nitrogen oxides or to heat a particle filter to its regeneration temperature.

Another aspect of the invention relates to an internal combustion engine with at least one combustion chamber, the internal combustion engine being connected with its outlet to an exhaust system. An electrically heatable catalytic converter is arranged in the exhaust system of the internal combustion engine and at least one further catalytic converter is arranged downstream of the electrically heatable catalytic converter. The internal combustion engine is in operative connection with a control device which is set up to carry out a method according to the invention for exhaust gas aftertreatment when a machine-readable program code is executed by the control device. In such an internal combustion engine, the pollutant emissions can be minimized by the electrically heated catalytic converter, since an efficient conversion of the pollutants in the exhaust gas flow is ensured, with the additional consumption and thus the carbon dioxide emissions being minimized through the selective control of the electrically heated catalytic converter.

In an advantageous embodiment of the internal combustion engine, it is provided that the electrically heatable catalytic converter has a heating power of at least 2 KW, preferably of at least 3 KW, particularly preferably of at least 4 KW. In order to ensure that the exhaust gas aftertreatment components, in particular the catalytic converters, are heated up sufficiently quickly to their respective operating temperature, in particular the respective light-off temperature of the catalytic converter, the electrically heatable catalytic converter must have a heating power of at least 2 KW. Due to a higher heating output, the respective light-off temperature is reached earlier with otherwise the same operating conditions.

In a further advantageous embodiment of the internal combustion engine, it is provided that the internal combustion engine is coupled to a generator, in particular to a belt starter generator, with a power supply of the electrically heated catalyst takes place directly through the generator. The electricity for the electrically heatable catalytic converter can be provided by a generator without the interposition of a battery. This is particularly helpful in a cold start phase at cold outside temperatures, especially at temperatures below 0 ° C, in order to relieve the battery in this phase and to generate the electricity directly by the generator. A belt starter generator enables a particularly simple and inexpensive variant of a generator to provide the electricity for heating the electrically heatable catalytic converter and to enable recuperation of the kinetic energy of a motor vehicle in overrun mode.

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

• 1 ein bevorzugtes Ausführungsbeispiel für ein Kraftfahrzeug mit einem Verbrennungsmotor zur Durchführung eines erfindungsgemäßen Verfahrens zur Abgasnachbehandlung;
• 2 ein weiteres Ausführungsbeispiel für ein Kraftfahrzeug mit einem Verbrennungsmotor zur Durchführung eines erfindungsgemäßen Verfahrens zur Abgasnachbehandlung;
• 3 ein Ablaufdiagramm zum getakteten An- und Abschalten eines elektrisch beheizbaren Katalysators in der Abgasanlage eines Verbrennungsmotors.

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

• 1 a preferred embodiment of a motor vehicle with an internal combustion engine for carrying out a method according to the invention for exhaust gas aftertreatment;
• 2 a further embodiment of a motor vehicle with an internal combustion engine for performing a method according to the invention for exhaust gas aftertreatment;
• 3 a flow chart for clocked switching on and off of an electrically heatable catalyst in the exhaust system of an internal combustion engine.

1 shows a schematic representation of a motor vehicle 1 with an internal combustion engine 10 . The internal combustion engine 10 is in this embodiment a direct injection diesel engine and has several combustion chambers 12th on. At the combustion chambers 12th is a fuel injector each 14th for injecting a fuel into the respective combustion chamber 12th arranged. The internal combustion engine 10 is with its outlet 18th with an exhaust system 20th connected. At the combustion chambers 12th inlet and outlet valves are arranged with which a fluidic connection from the combustion chambers 12th to the exhaust system 20th can be opened or closed.

The exhaust system 20th includes an exhaust duct 22nd , in which in the flow direction of an exhaust gas flow of the internal combustion engine 10 through the exhaust duct 22nd a turbine 34 of an exhaust gas turbocharger 24 and downstream of the turbine 34 an electrically heated catalyst 26th are arranged. The electrically heated catalytic converter 26th is a first catalyst 28 , in particular an oxidation catalytic converter or a NOx storage catalytic converter, connected downstream, which by the electrically heatable catalytic converter 26th can be heated. Downstream of the first catalyst 28 is a second catalyst 30th , especially a particulate filter 32 with a coating for the selective, catalytic reduction of nitrogen oxides (SCR coating) and further downstream a third catalytic converter 40 , in particular another SCR catalyst, arranged.

Upstream of the electrically heatable catalytic converter 26th is a first temperature sensor 36 and downstream of the first catalyst 28 a second temperature sensor 38 arranged. Downstream of the first catalyst 28 and upstream of the second catalyst 30th is a dosing element 42 for metering a reducing agent into the exhaust gas duct 22nd provided, which an exhaust mixer 44 is connected downstream for better uniform distribution of the reducing agent over the exhaust gas flow. Downstream of the second catalyst 30th and upstream of the third catalyst 40 is a second metering element 46 arranged, which a second exhaust mixer 48 is downstream.

The internal combustion engine 10 is with a gearbox 50 coupled over which the wheels 68 a drive axle 66 of the motor vehicle 1 are driven. Furthermore, the internal combustion engine 10 with a generator 52 connected, which is the kinetic energy of the internal combustion engine 10 converts it into electrical energy. Preferably the generator is 52 as a belt starter generator 56 executed and over a strap 54 with the internal combustion engine 10 connected. The generator 52 , 56 is via a first electrical line 58 with a control unit 70 to control the electrically heated catalytic converter 26th connected. The control unit 70 is via a second electrical line 60 with the electrically heated catalytic converter 26th connected. The control unit 70 is via a third electrical line 62 with a battery 64 of the motor vehicle 1 connected by the generator 52 , 56 is chargeable.

In 2 is another embodiment of a motor vehicle 1 with an internal combustion engine 10 shown in a schematic representation. With essentially the same structure as to 1 running is the internal combustion engine 10 in this exemplary embodiment designed as a direct-injection gasoline engine. This is on each of the combustion chambers 12th a spark plug 16 arranged to a combustible fuel-air mixture in the respective combustion chamber 12th to ignite.

In the exhaust system 20th is downstream of a turbine 34 of an exhaust gas turbocharger 24 an electrically heated catalyst 26th arranged, which a first catalyst 28 , in particular a three-way catalyst or a four-way catalyst, is connected downstream. Downstream of the first catalyst 28 is a second catalyst 30th provided, which is preferably designed as a three-way catalyst or four-way catalyst. Downstream of the turbine 34 and upstream of the electrically heatable catalyst 26th is a first temperature sensor 36 on the exhaust duct 22nd arranged. Downstream of the first catalyst 28 and upstream of the second catalyst 30th is a second temperature sensor 38 on the exhaust duct 22nd arranged. The temperature sensors are each connected to the control unit via signal lines 70 connected.

The approaches known from the prior art for using an electrically heatable catalyst 26th In the case of low engine loads, aim at additional heating of an exhaust gas mass flow that is too cold with a permanent performance of the electrically heated catalytic converter 26th from. This permanent power should be selected as low as possible, as this leads to increased fuel consumption of the internal combustion engine 10 leads. The additional load on the internal combustion engine 10 to generate the electrical energy required to electrically heat the electrically heated catalytic converter 26th can also be perceived acoustically by the driver as a loss of comfort.

According to the invention, the proposed method for exhaust gas aftertreatment of an internal combustion engine takes place 10 discontinuous operation of the electrically heatable catalyst 26th . The time response of at least part of the controlled system in the exhaust gas aftertreatment is provided by the electrically heatable catalytic converter 26th up to the catalytic converter to be heated 28 , 30th , 40 considered. The threshold temperatures T _S1 , T _S2 for switching the electrically heatable catalytic converter on and off 26th are dependent on the expected future temperature of the respective catalytic converter 28 , 30th , 40 elected. These threshold _{temperatures T S1} , T _S2 can be composed of a target temperature and an offset temperature, or an implicit combination of these temperatures to form an overall temperature threshold.

In this context, the target temperature is the minimum temperature to be achieved by an exhaust gas aftertreatment component, in particular the light-off temperature of a catalytic converter. This target temperature can be variable. The offset temperature defines an additional lead by which the target temperature is increased.

The discontinuous operation of the electrically heated catalytic converter 26th for a delayed temperature response of the downstream exhaust aftertreatment components 28 , 30th , 32 , 40 . A heating operation with the same average heating output but different intervals and / or durations of the heating phases leads to a different oscillation of the temperatures of the exhaust gas aftertreatment components 28 , 30th , 32 , 40 . Such a discontinuous heating operation is in 3 shown. Decisive for an efficient conversion of the pollutants in the exhaust gas flow of the internal combustion engine 10 regarding the minimum or maximum temperatures of the exhaust aftertreatment components 28 , 30th , 32 , 40 is maintaining the respective target temperature. With larger amplitudes of the oscillation, larger deviations between the expected and actual temperature of the respective exhaust gas aftertreatment component can occur 28 , 30th , 32 , 40 which arise, for example, from model errors in the modeling of the heat transfer in the exhaust system 20th , Measurement errors of sensors 36 , 38 or sudden changes in the driving profile. The offset temperature takes into account such influences, for example due to a larger offset when a heating period of the electrically heatable catalytic converter ended a long time ago 26th .

With the approach described, it is possible to operate the electrically heatable catalyst discontinuously 26th to represent. Thus, the operation of the electrically heatable catalytic converter 26th at least partially over time from the current heating or cooling behavior of the exhaust gas aftertreatment components 28 , 30th , 32 , 40 be carried out decoupled. This is advantageous because the operation instead, for example, at operating points of the internal combustion engine 10 can take place that are favorable in terms of consumption, emissions, acoustics or driving comfort. The electrically heatable catalytic converter can also be operated in particularly favorable driving situations, for example when energy is generated from an electrical deceleration of the motor vehicle 1 is provided as part of the recuperation, or the driving noises mask the acoustic impairment.

In 3 is such a heating process in the exhaust system 20th shown. The soaking time of the monolith of the first catalyst 28 in this example is about 55 s. This time depends on the exhaust gas mass flow of the internal combustion engine 10 , whereby a higher exhaust gas mass flow leads to a lower soaking time. The time between switching off the electrically heated catalytic converter 26th and reaching the minimum operating temperature of the first catalyst 28 in this example is about 80 s The temperature of the first catalyst 28 drops by around 20 ° C in 30 s.An assumed deviation of 5% is an error that covers a probability of more than 95%. Thus, by choosing the lower threshold _{temperature T s1} , a distance of approximately 13% from the light-off temperature of the first catalytic converter 28 can be achieved that the exhaust gases of the internal combustion engine 10 even in the event of unforeseen operating conditions of the internal combustion engine 10 are always effectively converted.

List of reference symbols

1

Motor vehicle

10

Internal combustion engine

12th

Combustion chamber

14th

Fuel injector

16

spark plug

18th

Outlet

20th

Exhaust system

22nd

Exhaust duct

24

Exhaust gas turbocharger

26th

electrically heated catalytic converter

28

first catalyst

30th

second catalyst

32

Particle filter

34

turbine

36

first temperature sensor

38

second temperature sensor

40

third catalyst

42

first metering element

44

first exhaust mixer

46

second metering element

48

second exhaust mixer

50

transmission

52

generator

54

belt

56

Belt starter generator

58

first electrical line

60

second electrical line

62

third electrical line

64

battery

66

Drive axle

68

wheel

70

Control unit

Claims (10)

Method for exhaust gas aftertreatment of an internal combustion engine (10) with at least one combustion chamber (12), wherein the internal combustion engine (10) is connected with its outlet (18) to an exhaust system (20) in which an electric heatable catalyst (26) and downstream of the electrically heatable catalyst (26) at least one further catalyst (28, 30, 40) is arranged, characterized in that a temperature (T _KAT ) of a catalyst (28, 30, 40) is determined or calculated , this temperature (T _KAT ) being compared with a first threshold _{temperature (T s1} ), the electrically heatable catalyst (26) being activated when the calculated or determined temperature (T _KAT ) is below the first threshold _{temperature (T s1} ) and wherein this temperature (T _KAT ) is compared with a second threshold _{temperature (T s2} ), the electrically heatable catalytic converter (26) being deactivated if the calculated or determined temperature (T _KAT ) is above the second threshold _{temperature (T s2} ). Procedure according to Claim 1 , characterized in that the transfer behavior of the heat transfer from the electrically heatable catalytic converter (26) to the catalytic converter (28, 30, 40) following in the flow direction is modeled. Procedure according to Claim 1 or 2 , characterized in that a catalytic converter (28, 30, 40) is heated by the electrically heatable catalytic converter (26) as a function of the expected temperature (T _EX ) of a catalytic converter (28, 30, 40) in the exhaust system (20) . Method according to one of the Claims 1 to 3 , characterized in that the calculated or determined temperature (T _KAT ) of a catalytic converter (28, 30, 40) and / or the expected temperature (T _Ex ) of a catalytic converter (28, 30, 40) is multiplied or added by an offset factor in order to compensate for an error in the determination of the calculated or determined temperature (T _KAT ) of the catalytic converter (28, 30, 40) and / or the expected temperature (T _Ex ) of the catalytic converter (28, 30, 40). Method according to one of the Claims 1 to 4th , characterized in that the electrically heatable catalytic converter (26) is operated for a defined time interval. Method according to one of the Claims 1 to 5 , characterized in that the internal combustion engine (10) is coupled to a generator (52, 56), the electrical energy for heating the electrically heatable catalyst (26) being provided by the generator (52, 56). Method according to one of the Claims 1 to 6th , characterized in that the electrically heatable catalytic converter (26) is heated in overrun mode of the internal combustion engine (10). Method according to one of the Claims 1 to 7th , characterized in that the electrically heatable catalytic converter (26) is activated as a function of the position of an exhaust gas aftertreatment component (28, 30, 40) arranged downstream of the electrically heatable catalytic converter (26) in the exhaust system (20). Internal combustion engine (10) with at least one combustion chamber (12), the internal combustion engine (10) having its outlet (18) connected to an exhaust system (20), an electrically heatable catalytic converter (26) in the exhaust system (20) and downstream of the electrically heatable catalytic converter (26) at least one further catalytic converter (28, 30, 40) is arranged, as well as with a control unit (70) which is set up to implement a method according to one of the Claims 1 to 8th to be carried out when a machine-readable program code is executed by the control device (70). Internal combustion engine (10) after Claim 9 , wherein the electrically heatable catalyst (26) has a heating power of at least 2 KW.

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