Methods for exhaust aftertreatment of an internal combustion engine and internal combustion engine

Abstract

Method for exhaust 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 electrically heated catalyst (26) is arranged in the direction of flow of an exhaust stream of the internal combustion engine (10) and at least one further catalyst (28, 30, 40) is arranged downstream of the electrically heated catalyst (26), wherein a temperature (T KAT ) one of which at least one further catalyst (28, 30, 40) is determined or calculated, the calculated or determined temperature (T KAT ) with a first threshold temperature (T S1 ) is compared, wherein the electrically heated catalyst (26) is activated when the calculated or determined temperature (T KAT ) below the first threshold temperature (T S1 ) lies, and the calculated or determined temperature (TKAT ) with a second threshold temperature (T S2 ) is compared, whereby the electrically heated catalyst (26) is deactivated when the calculated or determined temperature (T KAT ) above the second threshold temperature (T S2 ) lies, the heating of the further catalyst (28, 30, 40) by the electrically heated catalyst (26) as a function of an expected temperature (T EX ) of the further catalyst (28, 30, 40) in the exhaust system (20) takes place, the calculated or determined temperature (T KAT ) of the further catalyst (28, 30, 40) and / or the expected temperature (T Ex ) of the further catalyst (28, 30, 40) is multiplied or added with an offset factor to eliminate an error in determining the calculated or determined temperature (T). KAT ) of the further catalyst (28, 30, 40) and / or the expected temperature (T EX) to compensate for the further catalyst (28, 30, 40), and the internal combustion engine (10) is coupled to a generator (52, 56), whereby the electrical energy for heating the electrically heated catalyst (26) is provided by the generator (52, 56).

Description

[0001] The invention relates to a method for exhaust aftertreatment of an internal combustion engine and to an internal combustion engine with an exhaust aftertreatment system for carrying out such a method according to the preamble of the independent claims.

[0002] Current and increasingly stringent emissions legislation places high demands on raw engine emissions and exhaust aftertreatment in combustion engines. The requirements for further reductions in fuel consumption and the tightening of emissions standards regarding permissible nitrogen oxide emissions pose challenges for engine developers. In gasoline engines, exhaust gas purification is achieved in the familiar manner via a three-way catalytic converter, as well as additional catalysts upstream and downstream of the three-way converter. Diesel engines currently employ exhaust aftertreatment systems that include an oxidation catalyst or a NOx storage catalyst, a catalyst for the selective catalytic reduction of nitrogen oxides (SCR catalyst), a particulate filter for the separation of soot particles, and, if necessary, further catalysts.To meet the stringent requirements for minimal nitrogen oxide emissions, exhaust aftertreatment systems are known which feature two SCR catalysts connected in series, with each SCR catalyst having a metering element upstream for the injection of a reducing agent. A synthetic aqueous urea solution is preferably used as the reducing agent, which is mixed with the hot exhaust gas stream in a mixing device upstream of the SCR catalyst. This mixing heats the aqueous urea solution, releasing ammonia into the exhaust gas duct. A commercially available aqueous urea solution generally consists of 32.5% urea and 67.5% water.

[0003] With the introduction of EU6 emissions standards, a limit for particle number is prescribed for gasoline engines, which in many cases necessitates the use of a gasoline particulate filter (GPF). These soot particles are produced particularly after a cold start of the combustion engine due to incomplete combustion combined with a substoichiometric air-fuel ratio and cold cylinder walls during the cold start. The cold start phase is therefore crucial for compliance with the legally prescribed particle limits. During normal driving, the GPF continues to accumulate soot. To prevent excessive exhaust backpressure, the GPF must be regenerated continuously or periodically. An increase in exhaust backpressure can lead to increased fuel consumption, reduced power output, impaired engine smoothness, and even misfires.To thermally oxidize the soot trapped in the gasoline particulate filter with oxygen, a sufficiently high temperature level combined with the simultaneous presence of oxygen in the exhaust system of the gasoline engine is necessary. Since modern gasoline engines are normally operated without excess oxygen at a stoichiometric air-fuel ratio (λ=1), additional measures are required. These measures include, for example, increasing the temperature by adjusting the ignition timing, temporarily leaning out the mixture, injecting secondary air into the exhaust system, or a combination of these measures. Currently, retarding the ignition timing in combination with leaning out the mixture is preferred, as this method requires no additional components and can supply a sufficient amount of oxygen at most operating points of the gasoline engine.

[0004] Furthermore, electrically heated catalysts are known from the prior art, with which heat can be introduced into the exhaust system essentially independently of the operation of the combustion engine in order to heat one or more exhaust aftertreatment components to their operating temperature.

[0005] From US patent 2014 / 0366509 A1, a method for operating an exhaust aftertreatment device with an electric heating element for heating an exhaust gas stream from the internal combustion engine or a surface of the exhaust aftertreatment device is known. An additive is introduced into the exhaust system at a metering point in such a way that it comes into contact with the electric heating element to improve the evaporation of the additive. Based on at least one operating variable, an operating condition is identified in which deposits can form on the electric heating element. Depending on this operating condition, a switching frequency of the electrically heated catalyst is determined, whereby deposits on the electrically heated catalyst are prevented by the pulsed activation and deactivation of the electric heating element at a defined switching frequency.

[0006] DE 10 2009 038 110 A1 discloses a method for controlling an exhaust aftertreatment system for a motor vehicle with an internal combustion engine. In this method, an exhaust gas temperature profile of the internal combustion engine is determined based on a digital map and the expected operating data of the internal combustion engine.

[0007] From DE 10 2012 202935 A1, an internal combustion engine with a start-stop system is known. The internal combustion engine has a fuel type module that determines the fuel type of the fuel supplied to the engine. A threshold module determines a first threshold based on the fuel type. A temperature module estimates the temperature of a catalyst in the exhaust system of the internal combustion engine. A comparison module compares the temperature with the first threshold and generates a comparison signal. A power module sets the power output to a heating circuit based on the comparison signal. The heating circuit is configured to increase the temperature of the catalyst. The power module sets the power output to the heating circuit to increase the temperature of the catalyst when the internal combustion engine is switched off.A machine control module performs a shutdown and restart of the internal combustion engine to reduce the idle time of the internal combustion engine.

[0008] The invention is based on the objective of keeping the exhaust aftertreatment components permanently at a temperature level at which efficient conversion of the pollutants in the exhaust stream of the combustion engine is possible and of improving the energy efficiency of the exhaust aftertreatment system.

[0009] According to the invention, this problem is solved by a method for the exhaust aftertreatment of an internal combustion engine with at least one combustion chamber. The internal combustion engine is connected via its exhaust outlet to an exhaust system in which an electrically heated catalyst is arranged in the direction of flow of an exhaust stream from the internal combustion engine, and at least one further catalyst is arranged downstream of the electrically heated catalyst. It is provided that the temperature of one of the at least one further catalyst is determined or calculated, and this temperature is compared with a first threshold temperature. The electrically heated catalyst is activated when the calculated or determined temperature is below the first threshold temperature.The temperature is compared to a second threshold temperature, whereby the electrically heated catalyst is deactivated if the calculated or determined temperature is above the second threshold temperature. This enables particularly energy-efficient operation of the electrically heated catalyst, similar to a two-point controller. Electrical heating of the exhaust system only occurs when the temperatures of the exhaust aftertreatment components are too low to ensure efficient conversion of pollutants in the exhaust stream, and when insufficient heat is introduced into the exhaust system via the combustion engine's exhaust stream to heat the exhaust aftertreatment components to their operating temperature. This minimizes the period during which the electrically heated catalyst is activated, thereby reducing the combustion engine's fuel consumption.Furthermore, efficient conversion of these pollutants can be ensured in all operating conditions. After a cold start of the combustion engine or after low-load operation, the exhaust aftertreatment components are heated simultaneously by the exhaust gas flow of the combustion engine and by the electrically heated catalyst, allowing them to quickly reach their light-off temperature, above which efficient conversion of pollutants by the respective catalyst is possible.

[0010] The features listed in the dependent claims enable advantageous improvements and non-trivial further developments of the exhaust aftertreatment method for an internal combustion engine specified in the independent claim.

[0011] In a preferred embodiment of the invention, the heat transfer behavior from the electrically heated catalyst to the catalyst downstream in the flow direction is modeled. This allows for further optimization of the operation of the electrically heated catalyst, as the dead time between heat input from the electrically heated catalyst and an actual temperature increase at a catalyst downstream in the flow direction can be taken into account in the heating strategy. In particular, if the catalyst is at risk of cooling down, the electrically heated catalyst can be activated in time before the catalyst temperature drops below its light-off temperature. At low engine loads or during overrun, the exhaust gas may be colder than the light-off temperature of the respective catalyst or any other operating temperature of an exhaust aftertreatment component.Despite the combustion engine being actively running, the exhaust aftertreatment components would cool down in this operating state, so efficient conversion of pollutants in the exhaust stream would no longer be guaranteed. By modeling the heat transfer from the electrically heated catalyst to the downstream catalyst, the first threshold at which the electrically heated catalyst is activated can be selected close to the respective light-off temperature, thus further minimizing the operating time of the electrically heated catalyst.

[0012] According to the invention, the heating of the secondary catalyst by the electrically heated catalyst is determined by the expected temperature of the secondary catalyst in the exhaust system. If an increase in catalyst temperature is expected due to high-load operation of the combustion engine, the heating power of the electrically heated catalyst can be reduced or the heating element of the electrically heated catalyst can be switched off, since an increase in catalyst temperature is to be expected in such an operating condition. However, if a drop in catalyst temperature is expected due to overrun or a low-load phase, the electrically heated catalyst is activated to prevent the catalyst from cooling below its light-off temperature.

[0013] According to the invention, it is provided that the calculated or determined temperature of the further catalyst or the expected temperature of the further catalyst is multiplied or added by an offset factor in order to compensate for an error in determining the calculated or determined temperature of the further catalyst and / or the expected temperature of the further catalyst.

[0014] The more statistically uncertain / error-prone the expected temperature is, for example, because a longer cooling phase precedes the temperature calculation, the larger the offset factor is chosen. The expected temperature is the unique 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 uncertainty due to measurement errors, which can be compensated for alternatively or additionally by the offset factor. The activation threshold for the electrically heated catalyst is determined from the calculated target temperature and the offset factor, which can be added to or multiplicatively applied to the expected temperature.This ensures that even in the event of a model deviation, effective and efficient exhaust aftertreatment of the combustion engine's exhaust stream is always possible.

[0015] In an advantageous embodiment of the method, the electrically heated catalyst is operated for a defined time interval. Heating with defined intervals leads to varying temperature oscillations of the catalysts. This allows the operation of the electrically heated catalyst to be at least partially decoupled from the actual temperature or the heating and cooling behavior of the respective catalyst. This is advantageous because the electrically heated catalyst can be operated at combustion engine operating points that are favorable with regard to fuel consumption, emissions, acoustics, or driving comfort. Likewise, the electrically heated catalyst can be operated in particularly favorable driving situations.

[0016] According to the invention, the internal combustion engine is coupled to a generator, with the generator supplying the electrical energy for heating the electrically heated catalyst. The generator allows the engine's operating point to be shifted at low engine loads, thus minimizing the risk of the catalysts cooling below their respective light-off temperatures. Furthermore, the generator reduces the load on a battery connected to it, enabling electrical heating of the electrically heated catalyst without functional impairment even when the battery's charge is low.

[0017] In an advantageous embodiment of the exhaust aftertreatment method, the electrically heated catalyst is heated during engine braking. During engine braking, energy can be recuperated by the generator. This energy can then be used to heat the electrically heated catalyst, thus efficiently maintaining the exhaust aftertreatment components, particularly the catalysts, at their respective operating temperatures.

[0018] In a preferred embodiment of the invention, the electrically heated catalyst is controlled depending on the position of an exhaust aftertreatment component located downstream of the electrically heated catalyst in the exhaust system. Thus, the electrically heated catalyst can be used, for example, to maintain an SCR catalyst within its temperature range necessary for the efficient conversion of nitrogen oxides or to heat a particulate filter to its regeneration temperature.

[0019] Another aspect of the invention relates to an internal combustion engine with at least one combustion chamber, wherein the internal combustion engine is connected to an exhaust system via its exhaust outlet. An electrically heated catalyst and at least one further catalyst are arranged in the exhaust system of the internal combustion engine. The internal combustion engine is operatively connected to a control unit, which is configured to carry out an exhaust aftertreatment method according to the invention when a machine-readable program code is executed by the control unit. In such an internal combustion engine, pollutant emissions can be minimized by the electrically heated catalyst, since efficient conversion of the pollutants in the exhaust stream is ensured, and the selective control of the electrically heated catalyst minimizes increased fuel consumption and thus carbon dioxide emissions.

[0020] In an advantageous embodiment of the combustion engine, the electrically heated catalyst has a heating output of at least 2 kW, preferably at least 3 kW, and particularly preferably at least 4 kW. To ensure sufficiently rapid heating of the exhaust aftertreatment components, especially the catalysts, to their respective operating temperatures, and in particular the respective light-off temperature of the catalyst, a heating output of at least 2 kW for the electrically heated catalyst is necessary. With a higher heating output, the respective light-off temperature is reached correspondingly sooner under otherwise identical operating conditions.

[0021] In a further advantageous embodiment of the internal combustion engine, the engine is coupled to a generator, in particular a belt-driven starter-generator, with the electrically heated catalyst being powered directly by the generator. The generator can provide the current for the electrically heated catalyst without the need for a battery. This is particularly helpful during cold starts at low ambient temperatures, especially below 0°C, to relieve the battery during this phase and generate the current directly. A belt-driven starter-generator offers a particularly simple and cost-effective generator option for providing the current to heat the electrically heated catalyst and for enabling the recuperation of the vehicle's kinetic energy during deceleration.

[0022] Unless otherwise stated in individual cases, the various embodiments of the invention mentioned in this application can be advantageously combined with one another.

[0023] The invention is explained below in exemplary embodiments with reference to the accompanying drawings. Identical components or components with the same function are identified by the same reference numerals in the different figures. The figures show: Fig. 1 a preferred embodiment for a motor vehicle with an internal combustion engine for carrying out a method according to the invention for exhaust aftertreatment; Fig. 2 a further embodiment for a motor vehicle with an internal combustion engine for carrying out a method according to the invention for exhaust aftertreatment; Fig. 3 a flowchart for the timed switching on and off of an electrically heated catalyst in the exhaust system of an internal combustion engine.

[0024] Fig. Figure 1 shows a schematic representation of a motor vehicle 1 with an internal combustion engine 10. In this embodiment, the internal combustion engine 10 is a direct-injection diesel engine and has several combustion chambers 12. A fuel injector 14 is arranged on each of the combustion chambers 12 for injecting fuel into the respective combustion chamber 12. The internal combustion engine 10 is connected to an exhaust system 20 via its exhaust outlet 18. Inlet and outlet valves are arranged on the combustion chambers 12, which can open or close a fluidic connection between the combustion chambers 12 and the exhaust system 20.

[0025] The exhaust system 20 comprises an exhaust channel 22 in which, in the direction of flow of an exhaust gas stream from the combustion engine 10 through the exhaust channel 22, a turbine 34 of an exhaust gas turbocharger 24 and, downstream of the turbine 34, an electrically heated catalyst 26 are arranged. A first catalyst 28, in particular an oxidation catalyst or a NOx storage catalyst, is connected downstream of the electrically heated catalyst 26 and can be heated by the electrically heated catalyst 26. Downstream of the first catalyst 28, a second catalyst 30, in particular a particulate filter 32 with a coating for the selective catalytic reduction of nitrogen oxides (SCR coating), and further downstream a third catalyst 40, in particular another SCR catalyst, are arranged.

[0026] Upstream of the electrically heated catalyst 26, a first temperature sensor 36 is arranged, and downstream of the first catalyst 28, a second temperature sensor 38 is arranged. Downstream of the first catalyst 28 and upstream of the second catalyst 30, a metering element 42 is provided for metering a reducing agent into the exhaust gas channel 22. An exhaust gas mixer 44 is connected downstream of the metering element 42 to improve the even distribution of the reducing agent across the exhaust gas stream. Downstream of the second catalyst 30 and upstream of the third catalyst 40, a second metering element 46 is arranged, followed by a second exhaust gas mixer 48.

[0027] The internal combustion engine 10 is coupled to a transmission 50, which drives the wheels 68 of a drive axle 66 of the motor vehicle 1. Furthermore, the internal combustion engine 10 is connected to a generator 52, which converts the kinetic energy of the internal combustion engine 10 into electrical energy. Preferably, the generator 52 is designed as a belt-driven starter-generator 56 and is connected to the internal combustion engine 10 via a belt 54. The generator 52, 56 is connected via a first electrical line 58 to a control unit 70 for controlling the electrically heated catalyst 26. The control unit 70 is connected via a second electrical line 60 to the electrically heated catalyst 26. The control unit 70 is connected via a third electrical line 62 to a battery 64 of the motor vehicle 1, which can be charged by the generator 52, 56.

[0028] In Fig. Figure 2 shows a further embodiment of a motor vehicle 1 with an internal combustion engine 10 in schematic representation. With essentially the same construction as shown in Figure 2, the following applies: Fig. In this embodiment, the internal combustion engine 10 is designed as a direct-injection gasoline engine. For this purpose, a spark plug 16 is arranged in each of the combustion chambers 12 to ignite a combustible fuel-air mixture in the respective combustion chamber 12.

[0029] In the exhaust system 20, an electrically heated catalyst 26 is arranged downstream of a turbine 34 of an exhaust gas turbocharger 24. A first catalyst 28, preferably a three-way or four-way catalyst, is connected downstream of the first catalyst 28. A second catalyst 30, preferably a three-way or four-way catalyst, is provided downstream of the first catalyst 28. A first temperature sensor 36 is arranged on the exhaust gas duct 22 downstream of the turbine 34 and upstream of the electrically heated catalyst 26. A second temperature sensor 38 is arranged on the exhaust gas duct 22 downstream of the first catalyst 28 and upstream of the second catalyst 30. The temperature sensors are each connected to the control unit 70 via signal lines.

[0030] The approaches known from the prior art for using an electrically heated catalyst 26 aim, in the case of low engine loads, to additionally heat an excessively cold exhaust gas mass flow with a continuous power output of the electrically heated catalyst 26. This continuous power output should be kept as low as possible, as this leads to increased fuel consumption of the combustion engine 10. Furthermore, the additional load on the combustion engine 10 for generating the necessary electrical energy for electrically heating the electrically heated catalyst 26 can be perceived by the driver as a loss of comfort.

[0031] According to the invention, the proposed method for exhaust aftertreatment of an internal combustion engine 10 involves discontinuous operation of the electrically heated catalyst 26. The temporal response of at least part of the control loop in the exhaust aftertreatment system, from the electrically heated catalyst 26 to the catalyst 28, 30, 40 to be heated, is taken into account. The threshold temperatures T S1 , T S2 The threshold temperatures Te for switching the electrically heated catalyst 26 on and off are selected depending on the expected future temperature of the respective catalyst 28, 30, 40. S1 , T S2 They can consist of a target temperature and an offset temperature, or an implicit combination of these temperatures to form an overall temperature threshold.

[0032] In this context, the target temperature is the minimum achievable temperature of an exhaust aftertreatment component, specifically the light-off temperature of a catalyst. This target temperature can be variable. The offset temperature defines an additional margin by which the target temperature is increased.

[0033] The discontinuous operation of the electrically heated catalyst 26 leads to a delayed temperature response of the downstream exhaust aftertreatment components 28, 30, 32, 40. Heating operation with the same average heating power, but different intervals and / or durations of the heating phases, leads to different temperature oscillations of the exhaust aftertreatment components 28, 30, 32, 40. Such discontinuous heating operation is in Fig. Figure 3 illustrates this. Crucial for the efficient conversion of pollutants in the exhaust gas stream of the combustion engine 10 with respect to the minimum or maximum temperatures of the exhaust aftertreatment components 28, 30, 32, 40 is maintaining the respective target temperature. Larger oscillation amplitudes can lead to greater deviations between the expected and actual temperature of the respective exhaust aftertreatment component 28, 30, 32, 40, which can result, for example, from model errors in the heat transfer modeling of the exhaust system 20, measurement errors of sensors 36, 38, or sudden changes in the driving profile. The offset temperature takes such influences into account, for example, by a larger offset when the end of a heating period for the electrically heated catalyst 26 occurred some time ago.

[0034] The described approach makes it possible to represent discontinuous operation of the electrically heated catalyst 26. Thus, the operation of the electrically heated catalyst 26 can be at least partially decoupled from the current heating or cooling behavior of the exhaust aftertreatment components 28, 30, 32, 40. This is advantageous because, instead, operation can take place, for example, at operating points of the combustion engine 10 that are favorable with regard to fuel consumption, emissions, acoustics, or driving comfort. Likewise, the operation of the electrically heated catalyst can occur in particularly favorable driving situations, for example, when energy is provided from electric deceleration of the vehicle 1 during recuperation, or when the driving noise masks the acoustic disturbance.

[0035] In Fig.Figure 3 shows such a heating process in the exhaust system 20. The heating time of the monolith of the first catalyst 28 is approximately 55 s in this example. This time depends on the exhaust mass flow rate of the combustion engine 10, with a higher exhaust mass flow rate resulting in a shorter heating time. The time between switching off the electrically heated catalyst 26 and reaching the minimum operating temperature of the first catalyst 28 is approximately 80 s in this example. The temperature of the first catalyst 28 drops by approximately 20°C in 30 s. An assumed deviation of 5% is an error that covers a probability of more than 95%. Thus, by selecting the lower threshold temperature T S1with a distance of about 13% from the light-off temperature of the first catalyst 28, that the exhaust gases of the combustion engine 10 are always effectively converted even under unforeseen operating conditions of the combustion engine 10. Reference symbol list 1 motor vehicle 10 Internal combustion engine 12 Combustion chamber 14 Fuel injector 16 Spark plug 18 Outlet 20 Exhaust system 22 Exhaust duct 24 exhaust gas turbochargers 26 electrically heated catalyst 28 first catalyst 30 second catalyst 32 particle filters 34 Turbine 36 first temperature sensor 38 second temperature sensor 40 third catalyst 42 first dosing element 44 first exhaust gas mixer 46 second dosing element 48 second exhaust gas mixer 50 gearboxes 52 Generator 54 belts 56 Belt-driven 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

[1] Method for exhaust 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 electrically heated catalyst (26) is arranged in the direction of flow of an exhaust stream of the internal combustion engine (10) and at least one further catalyst (28, 30, 40) is arranged downstream of the electrically heated catalyst (26), wherein a temperature (T KAT ) one of which at least one further catalyst (28, 30, 40) is determined or calculated, the calculated or determined temperature (T KAT ) with a first threshold temperature (T S1 ) is compared, wherein the electrically heated catalyst (26) is activated when the calculated or determined temperature (T KAT ) below the first threshold temperature (T S1 ) lies, and the calculated or determined temperature (TKAT ) with a second threshold temperature (T S2 ) is compared, whereby the electrically heated catalyst (26) is deactivated when the calculated or determined temperature (T KAT ) above the second threshold temperature (T S2 ) lies, the heating of the further catalyst (28, 30, 40) by the electrically heated catalyst (26) as a function of an expected temperature (T EX ) of the further catalyst (28, 30, 40) in the exhaust system (20) takes place, the calculated or determined temperature (T KAT ) of the further catalyst (28, 30, 40) and / or the expected temperature (T Ex ) of the further catalyst (28, 30, 40) is multiplied or added with an offset factor to eliminate an error in determining the calculated or determined temperature (T). KAT ) of the further catalyst (28, 30, 40) and / or the expected temperature (T EX) to compensate for the further catalyst (28, 30, 40), and the internal combustion engine (10) is coupled to a generator (52, 56), whereby the electrical energy for heating the electrically heated catalyst (26) is provided by the generator (52, 56). [2] Method according to claim 1, characterized by , that the heat transfer behavior from the electrically heated catalyst (26) to the subsequent catalyst (28, 30, 40) in the flow direction is modeled. [3] Method according to one of claims 1 or 2, characterized by , that the operation of the electrically heated catalyst (26) takes place for a defined time interval. [4] Method according to any one of claims 1 to 3, characterized by , that the heating of the electrically heated catalyst (26) takes place during overrun operation of the internal combustion engine (10). [5] Method according to any one of claims 1 to 4, characterized by, that the electrically heated catalyst (26) is controlled depending on the position of a catalyst (28, 30, 40) arranged downstream of the electrically heated catalyst (26) in the exhaust system (20). [6] Internal combustion engine (10) with at least one combustion chamber (12), wherein the internal combustion engine (10) is connected to an exhaust system (20) via its outlet (18), wherein an electrically heated catalyst (26) is arranged in the exhaust system (20) and at least one further catalyst (28, 30, 40) is arranged downstream of the electrically heated catalyst (26), and with a control unit (70) which is configured to carry out a method according to one of claims 1 to 5 when a machine-readable program code is executed by the control unit (70). [7] Internal combustion engine (10) according to claim 6, wherein the electrically heated catalyst (26) has a heating power of at least 2 kW.

Images