Internal combustion engine and methods for heating the exhaust system of such an internal combustion engine

Abstract

Internal combustion engine (10), which is connected at its inlet (16) to an air supply system (20) and at its outlet (18) to an exhaust system (50), wherein a turbine (56) of an exhaust gas turbocharger (54) is arranged in the exhaust system (50) and a compressor (26) driven by the turbine (56) is arranged in the air supply system (20), wherein the internal combustion engine (10) has a high-pressure exhaust gas recirculation (44) which connects the exhaust system (50) upstream of the turbine (56) to the air supply system (20) downstream of the compressor (26), wherein the internal combustion engine (10) has a low-pressure exhaust gas recirculation (80) which connects the exhaust system (50) downstream of the turbine (56) to the air supply system (20) upstream of the compressor (26), wherein in the exhaust system (50) downstream of the turbine (56) and upstream of a branch (72) at which the low-pressure exhaust gas recirculation (80) branches off from the exhaust system (50),an exhaust aftertreatment component (60, 62, 64, 66, 68) is arranged, and wherein downstream of the branch (72) an exhaust flap (70) is arranged for controlling an exhaust gas flow recirculated via the low-pressure exhaust gas recirculation (80), wherein in the exhaust system (50) upstream of the exhaust aftertreatment component (60, 62, 64, 66, 68) an electrically heated catalyst (58) is arranged, by means of which the exhaust aftertreatment component (60, 62, 64, 66, 68) can be heated, and in the air supply system (20) an electrically driven compressor (40) is arranged, by means of which a fresh air flow can be supplied to the exhaust system (50) when the internal combustion engine (10) is at a standstill, characterized in that in the air supply system (20) downstream of an air filter (22) and upstream a junction (86) at which an exhaust gas recirculation channel (82) of the low-pressure exhaust gas recirculation (80) enters an intake channel (28) of the air supply system (20),a throttle valve (30) is arranged and the electrically heated catalyst (58) is arranged downstream of an oxidation catalyst (60) or a NOx storage catalyst (62) and upstream of a particulate filter (64).

Description

[0001] The invention relates to an internal combustion engine and a method for heating an exhaust system of such an internal combustion engine 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 (NOx) emissions pose a challenge 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 catalytic converter. Diesel engines currently employ exhaust aftertreatment systems that use an oxidation catalyst or a NOx reduction catalyst. XThe system comprises a storage catalyst, a catalyst for the selective catalytic reduction of nitrogen oxides (SCR catalyst), a particulate filter for the separation of soot particles, and optionally further catalysts. To meet the stringent requirements for minimal nitrogen oxide emissions, exhaust aftertreatment systems are known which have two SCR catalysts connected in series, with a metering element for adding a reducing agent upstream of each SCR catalyst. 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, causing it to release ammonia into the exhaust gas duct. A commercially available aqueous urea solution generally consists of 32.5% urea and 67.5% water.

[0003] DE 10 2017 213 004 A1 discloses an internal combustion engine with an intake manifold and an exhaust system, wherein the internal combustion engine has high-pressure and low-pressure exhaust gas recirculation. The internal combustion engine is turbocharged by means of an exhaust gas turbocharger. A heating device and, following the direction of flow, two exhaust aftertreatment components are arranged in the exhaust system of the internal combustion engine. DE 10 2017 213 004 A1 describes heating the exhaust aftertreatment components by means of a carrier airflow, which is generated by an electric auxiliary compressor in the intake manifold and is introduced into the exhaust system via the high-pressure exhaust gas recirculation, past the combustion chambers of the internal combustion engine.

[0004] From DE 10 2016 014 254 A1, a method for heating at least one exhaust aftertreatment device arranged in the exhaust tract of an internal combustion engine is known. The internal combustion engine is arranged in a motor vehicle, in particular in a hybrid vehicle, and serves to propel it. While combustion of fuel in the combustion chambers of the internal combustion engine is omitted, a flow path from the intake tract of the internal combustion engine to the exhaust tract is open, wherein an exhaust gas flow conveyed through the flow path is heated by an electric heating element.

[0005] DE 10 2018 213 349 A1 describes a proactive heating system for a vehicle, used to increase the temperature of an exhaust catalyst before engine ignition in order to reduce emissions. The proactive heating system is part of an exhaust system for a vehicle and comprises an electrically heated catalyst and an air pump, which are activated before engine ignition to raise the temperature of a three-way catalyst to such an extent that the catalyst is at the desired target threshold temperature or start-up temperature before engine ignition, thereby eliminating the delay in exhaust aftertreatment following a cold engine start. The proactive heating system addresses the high level of untreated emissions emitted by an internal combustion engine before the catalytic exhaust aftertreatment system reaches its start-up temperature.The proactive heating system heats the catalyst to the start-up temperature without burning hydrocarbon fuel, resulting in a reduction of raw engine emissions.

[0006] Furthermore, US patent 2009 / 0194079A1 discloses an internal combustion engine with an exhaust aftertreatment system, wherein the exhaust aftertreatment system has a low-pressure exhaust gas recirculation system and a throttle valve is arranged in the intake tract upstream of the inlet of the low-pressure exhaust gas recirculation system into the intake tract.

[0007] German patent DE 10 2017 113 366 A1 discloses a method for heating components of an exhaust aftertreatment system in a preheating phase before the combustion engine is started. An electrically heated catalyst is activated by a door contact switch, with the activation occurring well before the combustion engine is started. Simultaneously, fresh air is blown into the exhaust system or the cylinder head of the combustion engine by an electrically driven compressor designed as an air pump, in order to create an airflow through the exhaust system when the engine is stationary and to enable convective heat transfer.

[0008] German patent DE 10 2012 002 329 A1 discloses a method for heating components of an exhaust aftertreatment system before starting the internal combustion engine. An electrically heated catalyst is heated when the engine is not running, and an airflow generated by an electrically driven compressor is blown through the exhaust aftertreatment system while the engine is still not running. The airflow is further heated by other means while the engine remains off, heating a downstream underfloor catalyst to the start-up temperature before the internal combustion engine is started.

[0009] German patent application DE 10 2018 213 349 A1 discloses a method for heating components of an exhaust aftertreatment system before engine ignition. This method includes an electrically heated catalyst and a compressor designed as an air pump, which heat the temperature of a three-way catalyst to the desired start-up temperature before engine ignition. The compressor generates an airflow that passes through the electrically heated catalyst and the three-way catalyst. The temperature of the airflow increases in the electrically heated catalyst, thereby subsequently raising the temperature of the three-way catalyst to a predetermined temperature.

[0010] However, a disadvantage of the known solutions is that a lot of heat is lost through the exhaust duct, and therefore a correspondingly high heating power is needed to heat the catalyst to its light-off temperature before the combustion engine starts.

[0011] The invention is based on the objective of heating the exhaust aftertreatment components to their operating temperature as energy-efficiently as possible before the combustion engine is started, and of overcoming the disadvantages of the prior art.

[0012] According to the invention, this problem is solved by an internal combustion engine which is connected at its inlet to an air supply system and at its outlet to the exhaust system. A turbine of an exhaust gas turbocharger is arranged in the exhaust system, and a compressor driven by the turbine is arranged in the air supply system. The internal combustion engine has a high-pressure exhaust gas recirculation system that connects the exhaust system upstream of the turbine to the air supply system downstream of the compressor. In addition to the high-pressure exhaust gas recirculation system, the internal combustion engine has a low-pressure exhaust gas recirculation system that connects the exhaust system downstream of the turbine to the air supply system upstream of the compressor.In the exhaust system, an exhaust aftertreatment component is arranged downstream of the turbine and upstream of a branch where the low-pressure exhaust gas recirculation branches off from the exhaust system. Downstream of the branch, an exhaust flap is arranged to control the exhaust gas flow recirculated via the low-pressure exhaust gas recirculation. According to the invention, an electrically heated catalyst is arranged upstream of the exhaust aftertreatment component in the exhaust system, which heats the exhaust aftertreatment component. An electrically driven compressor is arranged in the air supply system. When the combustion engine is at a standstill, a fresh air flow is supplied to the exhaust system via this compressor to create a carrier air flow. This carrier air flow then heats the exhaust aftertreatment components convectively with the electrically heated catalyst before the combustion engine is started.Opening an exhaust gas recirculation valve in the high-pressure exhaust gas recirculation system creates a bypass to the combustion engine, allowing a carrier airflow generated by the electrically driven compressor to be fed into the exhaust system. Thanks to the electric drive, this can occur independently of the combustion engine's operation and therefore before the engine is started. The carrier airflow is heated by the electrically heated catalyst and transfers this heat convectively to the exhaust aftertreatment components located downstream of the catalyst. Closing the exhaust flap causes the carrier airflow to recirculate, enabling particularly efficient and rapid heating of the exhaust system and the exhaust aftertreatment components within it.This allows for efficient conversion of the pollutants contained in the exhaust stream of the combustion engine as soon as it is started, thereby reducing cold start emissions.

[0013] The features listed in the dependent claims enable advantageous improvements and non-trivial further developments of the internal combustion engine specified in the independent claim.

[0014] In a preferred embodiment of the invention, the air supply system comprises an intake duct from which a bypass branches off at a junction and rejoins the intake duct at an inlet, with the electrically driven compressor being arranged in the bypass. An electrically driven auxiliary compressor reduces the flow resistance in the intake duct, since the fresh air does not flow through the electrically driven compressor during normal operation, and thus the intake duct is not blocked by the electrically driven compressor.

[0015] In a further improvement of the invention, a three-way control flap is arranged at the inlet to control the airflow through the intake duct or the bypass. This prevents a carrier airflow generated by the electrically driven compressor from flowing back towards the air filter via the inlet and the intake duct. This reduces flow losses during the formation of a carrier airflow and its circulation through the intake duct, the exhaust duct, and the low-pressure exhaust gas recirculation system.

[0016] According to the invention, a throttle valve is arranged in the air supply system downstream of an air filter and upstream of an inlet where an exhaust gas recirculation channel of the low-pressure exhaust gas recirculation system opens into an intake channel of the air supply system. This prevents the carrier airflow recirculated via the low-pressure exhaust gas recirculation system from escaping towards the air filter. This minimizes flow losses during the circulation of the carrier airflow.

[0017] In an embodiment of the combustion engine not included in the invention, the electrically heated catalyst is arranged upstream of an oxidation catalyst or a NOx storage catalyst. This allows the oxidation catalyst or the NOx storage catalyst to be heated to its light-off temperature within a short time interval after the activation of the electrically heated compressor and the electrically heated catalyst. This shortens the time interval until the combustion engine can be started.

[0018] According to the invention, the electrically heated catalyst is arranged downstream of an oxidation catalyst or a NOx storage catalyst and upstream of a particulate filter. This allows the electrically heated catalyst to be used in an additional operating mode to heat the particulate filter to its regeneration temperature or to quickly reach the light-off temperature for the selective catalytic reduction of nitrogen oxides, provided the particulate filter has a corresponding (SCR) coating.

[0019] In a preferred embodiment of the internal combustion engine, the engine is a diesel engine. In principle, low-pressure exhaust gas recirculation offers an efficient way to reduce raw nitrogen oxide emissions, particularly in diesel engines. Therefore, such an exhaust aftertreatment system can be implemented in a diesel engine with few additional components and minimal extra effort.

[0020] Another aspect of the invention relates to a method for heating an exhaust system of such an internal combustion engine, which comprises the following steps: - Closing the exhaust flap, - Opening an exhaust gas recirculation valve in the high-pressure exhaust gas recirculation system, - Opening an exhaust gas recirculation valve in the low-pressure exhaust gas recirculation system, - Driving the electrically driven compressor, thereby creating a carrier airflow which is fed to the exhaust system via the intake manifold and the high-pressure exhaust gas recirculation, wherein the carrier airflow is heated by the electrically heated catalyst and the carrier airflow is fed back to an intake manifold of the air supply system via the low-pressure exhaust gas recirculation, wherein - the heating of the exhaust aftertreatment components is initiated even before the combustion engine is started.

[0021] Through an exhaust aftertreatment method according to the invention, the exhaust aftertreatment components already reach a higher temperature than the ambient temperature at the start of the combustion engine, so that less energy is required to heat the exhaust aftertreatment components to their respective light-off temperature, above which efficient conversion of the exhaust components contained in the combustion engine's exhaust stream is possible. This allows emissions to be significantly reduced during a cold start phase of the combustion engine.

[0022] It is particularly preferred if the combustion engine is only started when at least one exhaust aftertreatment component has reached its operating temperature.

[0023] Thus, from the moment the combustion engine starts, efficient conversion of pollutants in the exhaust stream is possible, thereby reducing cold-start emissions. Furthermore, the circulation of the carrier air stream enables particularly efficient heating of the exhaust system and the exhaust aftertreatment components located within it, as only a small amount of heat is lost through the walls of the exhaust duct and through leakage, and the circulating carrier air stream is efficiently heated by the electrically heated catalyst.

[0024] In a preferred embodiment of the method, a throttle valve is arranged in the intake duct downstream of an air filter and upstream of the inlet of a low-pressure exhaust gas recirculation duct, the throttle valve being closed for the purpose of carrying out the method. This reduces the amount of leakage, as the circulating carrier air flow cannot escape via the intake duct and through the air filter.

[0025] In a further improvement of the method, the air supply system is provided with an intake duct from which a bypass branches off at a junction and rejoins the intake duct at a junction. The electrically driven compressor is located in the bypass, and a three-way control valve is arranged at the junction to control the airflow through the intake duct or the bypass. The three-way control valve is positioned such that the bypass is connected to the intake of the internal combustion engine, preventing backflow of the carrier airflow towards the air filter. This ensures that the carrier airflow at the junction, downstream of the electrically driven compressor, is directed towards the intake of the internal combustion engine and does not escape against the flow direction towards the air filter.

[0026] In a preferred embodiment of the method, it is provided that the process is triggered before the start of an internal combustion engine by a signal transmitter, in particular by a radio remote control, a keyless go system, a proximity sensor, a seatbelt buckle sensor, a mobile phone, or a seat occupancy sensor. A corresponding sensor or signal transmitter can detect that the start of the internal combustion engine is imminent. The heating of the exhaust system can then be initiated a correspondingly short time before the start of the internal combustion engine, so that the driver of a motor vehicle experiences no or only a minimal loss of time and the exhaust aftertreatment components in the exhaust system have already reached their light-off temperature when the internal combustion engine starts.

[0027] Unless otherwise specified in individual cases, the various embodiments of the invention mentioned in this application can be advantageously combined with one another.

[0028] The invention is explained below using exemplary embodiments with reference to the accompanying drawings. These show: Fig. 1 An embodiment of an internal combustion engine with an air supply system and an exhaust system to heat the exhaust aftertreatment components before the start of the internal combustion engine. Fig. 2 a further embodiment of an internal combustion engine for reducing cold start emissions, as well as Fig. 3 a third embodiment of an internal combustion engine whose exhaust system can be heated before the internal combustion engine is started.

[0029] Fig. Figure 1 shows a schematic representation of an internal combustion engine 10 with an air supply system 20 and an exhaust system 50. 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 combustion chamber 12 for injecting fuel into the respective combustion chamber 12. The internal combustion engine 10 is connected to an air supply system 20 via its inlet 16 and to an exhaust system 50 via its outlet 18. The internal combustion engine 10 also includes a high-pressure exhaust gas recirculation system 44 with an exhaust gas recirculation line 46 and an exhaust gas recirculation valve 48, through which an exhaust gas flow from the internal combustion engine 10 can be recirculated from the outlet 18 to the inlet 16.Inlet valves and outlet valves are arranged on the combustion chambers 12, with which a fluidic connection from the air supply system 20 to the combustion chambers 12 or from the combustion chambers 12 to the exhaust system 50 can be opened or closed.

[0030] The air supply system 20 comprises an intake duct 28 in which, in the direction of fresh air flow through the intake duct 28, an air filter 22, an air mass meter 24 (in particular a hot-film air mass meter), and a compressor 26 of an exhaust gas turbocharger 54 are arranged. The air mass meter 24 can also be arranged in a filter housing of the air filter 22, so that the air filter 22 and the air mass meter 24 form a single assembly. An inlet 86 is provided downstream of the air filter 22 and upstream of the compressor 26, at which an exhaust gas recirculation duct 82 of a low-pressure exhaust gas recirculation system 80 opens into the intake duct 28 of the air supply system 20. Downstream of the compressor 26, a branch 34 is formed, at which a bypass 36 branches off from the extraction duct 28. An electrically driven compressor 40 is arranged in the bypass 36.Downstream of the electrically driven compressor 40, the bypass opens back into the intake duct 28 at an inlet 38. A 3-way control flap 42 is arranged at the inlet 38, with which the airflow through the intake duct 28 or through the bypass 36 can be controlled.

[0031] The exhaust system 50 comprises an exhaust duct 52 in which, in the direction of flow of exhaust gas from the combustion engine 10 through the exhaust duct 52, a turbine 56 of the exhaust gas turbocharger 54 is arranged, which drives the compressor 26 in the air supply system 20 via a shaft. The exhaust gas turbocharger 54 is preferably designed as an exhaust gas turbocharger with variable turbine geometry. For this purpose, adjustable guide vanes are arranged upstream of a turbine wheel of the turbine 56, by means of which the flow of exhaust gas onto the blades of the turbine 56 can be varied. Several exhaust gas aftertreatment components 58, 60, 62, 64, 66, 68 are provided downstream of the turbine 56. Immediately downstream of the turbine 56, an electrically heated catalyst 58 is provided as the first component of the exhaust gas aftertreatment, which is arranged upstream of an oxidation catalyst 60 or a NOx storage catalyst 62.Downstream of the exhaust gas flow from the combustion engine 10, following the oxidation catalyst 60 or the NOx storage catalyst 62, is a particulate filter 64, which is preferably provided with a coating 66 for the selective catalytic reduction of nitrogen oxides (SCR coating). Downstream of the particulate filter 64, a branch 72 is formed, at which an exhaust gas recirculation channel 82 branches off a low-pressure exhaust gas recirculation 80 from the exhaust gas channel 52. This exhaust gas recirculation channel 82 connects the exhaust gas channel 52 downstream of the particulate filter 64 with the intake channel 28 downstream of the air filter 22 and upstream of the compressor 26. An exhaust gas recirculation valve 84 is arranged in the exhaust gas recirculation channel 82, with which the exhaust gas recirculation channel 82 can be closed.

[0032] Downstream of branch 72, an exhaust flap 70 is provided in the exhaust channel 52, which can at least partially block the cross-section of the exhaust channel 52 in order to increase the exhaust back pressure in the exhaust channel 52 and thus control the exhaust gas recirculation rate via the low-pressure exhaust gas recirculation 80. A further exhaust aftertreatment component, in particular an SCR catalyst 68, can be arranged in the exhaust channel 52 downstream of branch 72. A metering valve 74 is arranged downstream of the oxidation catalyst 60 or the NOx storage catalyst 62 and upstream of the particulate filter 64, with which a reducing agent for the selective, catalytic reduction of nitrogen oxides, in particular an aqueous urea solution, can be metered into the exhaust channel 52.A metering valve 74 can be connected to an exhaust gas mixer 76 to improve the mixing of the exhaust gas flow with the reducing agent before it enters the particulate filter 64. Furthermore, a temperature sensor 88 is arranged in the exhaust system 50 to determine the temperature of the exhaust gas flow and / or the temperature of an exhaust aftertreatment component 60, 62, 64, 66, 68, so that the combustion engine 10 can be started when a threshold temperature T is reached in the exhaust system 50. S is achieved.

[0033] The internal combustion engine 10 is connected to an engine control unit 90, which is connected via signal lines (not shown) to the electrically heated catalytic converter 58, the fuel injectors 14 of the internal combustion engine 10, a control element for the exhaust flap 70, and a control element for the 3-way control flap 42. The electrically driven compressor 40 can also be controlled via the control unit 90 to generate a carrier airflow.

[0034] In Fig. Figure 2 shows a further embodiment of an internal combustion engine 10 with an air supply system 20 and an exhaust system 50. With essentially the same construction as shown in Figure 2, the following embodiments are also shown: Fig. As described in Figure 1, in this embodiment the electrically heated catalyst 58 is arranged downstream of the oxidation catalyst 60 or the NOx storage catalyst 62 and immediately upstream of the particulate filter 64. Thus, in another operating state, the electrically heated catalyst 58 can be used to heat the particulate filter 64 to a temperature necessary for its regeneration, to support in-engine heating measures for heating the particulate filter 64, or to quickly reach the light-off temperature for the selective catalytic reduction of nitrogen oxides (SCR) if the particulate filter has a corresponding coating. Furthermore, a charge air cooler 32 is arranged in the intake duct 28 downstream of the three-way control flap 42.Since no water circulates through the charge air cooler to dissipate heat from the intake air before the combustion engine 10 starts, heat loss is low during this phase. After the combustion engine 10 starts, the advantages of a charge air cooler 32 can be utilized in the usual manner.

[0035] In Fig. Figure 3 shows a further embodiment of an internal combustion engine 10 with an air supply system 20 and an exhaust system 50. With essentially the same construction as shown in Figure 3, the following embodiments are also shown: Fig.As illustrated in Figure 1, in this embodiment, a throttle valve 30 is provided in the air supply system 20 downstream of the air filter 22 and upstream of the inlet 86 of the exhaust gas recirculation channel 82 of the low-pressure exhaust gas recirculation system 80. This throttle valve prevents the circulating carrier air flow from flowing back out through the air filter 22. When the exhaust gas valve 70 and the throttle valve 30 are closed, and the exhaust gas recirculation valves 48 and 84 are open, a substantially closed circuit is created in which the carrier air flow can circulate. Furthermore, additional air can be supplied via the throttle valve 30 to compensate for losses due to leakage at the exhaust gas valve 70.

[0036] The basic idea of ​​the invention is to preheat the exhaust aftertreatment components before the combustion engine 10 is started. This is followed by activation of the electrically driven compressor, for example, by a remote control for unlocking the doors or another signal indicating an imminent start of the combustion engine 10. The battery 78 allows the electrically driven compressor 40 to be supplied with energy independently of the combustion engine 10. The battery 78 also provides the energy to close the exhaust flap 70 and open the exhaust gas recirculation valves 48, 84, thus creating a substantially closed circuit. The electrically driven compressor 40 generates a carrier airflow that circulates within this circuit and convectively transfers the heat generated by an electric heating element of the electrically heated catalyst 58 to the carrier airflow.In this way, the heat energy transferred to the air via the electrically heated catalyst 58 is utilized to the maximum extent. By arranging the electrically heated catalyst 58 directly upstream of an exhaust aftertreatment component 60, 62, 66, the corresponding exhaust aftertreatment component 60, 62, 66 is supplied with the maximum possible heat energy and heats up accordingly quickly to its operating temperature, so that the control unit 90 can enable the combustion engine 10 to be started. Reference symbol list 10 Internal combustion engine 12 Combustion chamber 14 Fuel injector 16 Admission 18 Outlet 20 Air supply system 22 air filters 24 air mass meters 26 compressors 28 Intake manifold 30 Throttle valve 32 Intercoolers 34 branching 36 Bypass 38 Junction 40 electrically driven compressors 42 3-way control valve 44 High-pressure exhaust gas recirculation 46 Exhaust gas recirculation line 48 Exhaust gas recirculation valve 50 Exhaust system 52 Exhaust duct 54 exhaust gas turbochargers 56 Turbine 58 electrically heated catalyst 60 Oxidation catalyst 62 NOx storage catalyst 64 particulate filters 66 SCR coating 68 SCR catalyst 70 Exhaust flap 72 branching 74 Metering valve 76 exhaust gas mixers 78 Battery 80 Low-pressure exhaust gas recirculation 82 Exhaust gas recirculation channel 84 Exhaust gas recirculation valve 86 Junction 88 Temperature sensor 90 Control unit

Claims

[1] Internal combustion engine (10), which is connected at its inlet (16) to an air supply system (20) and at its outlet (18) to an exhaust system (50), wherein a turbine (56) of an exhaust gas turbocharger (54) is arranged in the exhaust system (50) and a compressor (26) driven by the turbine (56) is arranged in the air supply system (20), wherein the internal combustion engine (10) has a high-pressure exhaust gas recirculation (44) which connects the exhaust system (50) upstream of the turbine (56) to the air supply system (20) downstream of the compressor (26), wherein the internal combustion engine (10) has a low-pressure exhaust gas recirculation (80) which connects the exhaust system (50) downstream of the turbine (56) to the air supply system (20) upstream of the compressor (26), wherein in the exhaust system (50) downstream of the turbine (56) and upstream of a branch (72) at which the low-pressure exhaust gas recirculation (80) branches off from the exhaust system (50),an exhaust aftertreatment component (60, 62, 64, 66, 68) is arranged, and wherein downstream of the branch (72) an exhaust flap (70) is arranged for controlling an exhaust gas flow recirculated via the low-pressure exhaust gas recirculation (80), wherein in the exhaust system (50) upstream of the exhaust aftertreatment component (60, 62, 64, 66, 68) an electrically heated catalyst (58) is arranged, by means of which the exhaust aftertreatment component (60, 62, 64, 66, 68) can be heated, and in the air supply system (20) an electrically driven compressor (40) is arranged, by means of which a fresh air flow can be supplied to the exhaust system (50) when the combustion engine (10) is at a standstill, , characterized by, that in the air supply system (20) downstream of an air filter (22) and upstream of an inlet (86) at which an exhaust gas recirculation channel (82) of the low-pressure exhaust gas recirculation (80) opens into an intake channel (28) of the air supply system (20), a throttle valve (30) is arranged and the electrically heated catalyst (58) is arranged downstream of an oxidation catalyst (60) or a NOx storage catalyst (62) and upstream of a particulate filter (64). [2] Internal combustion engine (10) according to claim 1, characterized by , that the air supply system (20) has an intake duct (28) from which a bypass (36) branches off at a junction (34) and rejoins the intake duct (28) at an inlet (38), wherein the electrically driven compressor (40) is arranged in the bypass (36). [3] Internal combustion engine (10) according to claim 2, characterized by, that a three-way control flap (42) is arranged at the inlet (38) to control the airflow through the intake duct (28) or the bypass (36). [4] Internal combustion engine (10) according to any one of claims 1 to 3, characterized by , that the internal combustion engine (10) is a diesel engine. [5] Method for heating an exhaust system (50) of an internal combustion engine (10) according to any one of claims 1 to 4, comprising the following steps: - Closing the exhaust flap (70), - Opening an exhaust gas recirculation valve (48) in the high-pressure exhaust gas recirculation (44); - Opening an exhaust gas recirculation valve (84) in the low-pressure exhaust gas recirculation (80); - Driving the electrically driven compressor (40), thereby forming a carrier air flow which is supplied to the exhaust system (50) via the intake duct (28) and the high-pressure exhaust gas recirculation (44), wherein the carrier air flow is heated by the electrically heated catalyst (58) and the carrier air flow is supplied again to an intake duct (28) of the air supply system (20) via the low-pressure exhaust gas recirculation (80), wherein - the heating of the exhaust aftertreatment components (60, 62, 64, 66, 68) is initiated before the combustion engine (10) is started. [6] Method according to claim 5, characterized by , that a throttle valve (30) is arranged in the intake channel (28) downstream of an air filter (22) and upstream of an inlet of an exhaust gas recirculation channel (82) of the low-pressure exhaust gas recirculation (80), wherein the throttle valve (30) is closed to carry out the procedure. [7] Method according to one of claims 5 or 6, characterized by , that the procedure is triggered before the start of an internal combustion engine (10) by a signal transmitter, in particular by a radio remote control, a keyless go system, a proximity sensor, a seat belt sensor, a mobile phone or a seat occupancy detection sensor.

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