DE102018130799B4 - Internal combustion engine and method of operating an internal combustion engine - Google Patents

Abstract

Internal combustion engine (10) with a crankshaft (14) and at least one combustion chamber (12), wherein the internal combustion engine (10) is connected with its inlet (16) to an intake tract (20), and wherein the internal combustion engine (10) with its outlet ( 18) is connected to an exhaust system (40), and to an exhaust gas turbocharger (28) with a compressor (30) and a turbine (50), which are connected to one another by a drive shaft (36), wherein in the direction of flow of an exhaust gas from the internal combustion engine ( 10) a combustion chamber (44) is arranged through the exhaust system (40) downstream of the outlet (18) of the internal combustion engine (10) and upstream of the turbine (50) of the exhaust gas turbocharger (28), characterized in that the drive shaft (36) of the exhaust gas turbocharger (28) can be connected at least indirectly to the crankshaft (14) of the internal combustion engine (10), with at least one exhaust gas aftertreatment component (52, 54, 56) for exhaust gas aftertreatment in the exhaust system (40) downstream of the turbine (50). Treatment of an exhaust gas of the internal combustion engine (10) is arranged, and wherein a secondary air compressor (60) is provided, which is connected to the combustion chamber (44) via a secondary air line (66).

Description

The invention relates to an internal combustion engine with an air supply system and with an exhaust system and a method for operating such an internal combustion engine according to the preamble of the independent patent claims.

The current exhaust gas legislation and one that will become increasingly strict in the future place high demands on engine raw emissions and the exhaust gas aftertreatment of combustion engines. The demands for a further reduction in consumption and the further tightening of the exhaust gas standards with regard to the permitted nitrogen oxide emissions represent a challenge for the engine developers. Catalyst upstream and downstream further catalysts. In diesel engines, exhaust gas aftertreatment systems are currently used which have oxidation catalytic converters, catalytic converters for the selective catalytic reduction of nitrogen oxides (SCR catalytic converter) and a particle filter for separating soot particles and, if necessary, further catalytic converters. Ammonia is preferably used as the reducing agent. Because handling pure ammonia is complicated, vehicles usually use a synthetic, aqueous urea solution, which is mixed with the hot exhaust gas flow in a mixing device upstream of the SCR catalytic converter. This mixing heats up the aqueous urea solution, with the aqueous urea solution releasing ammonia in the exhaust gas duct. A commercially available, aqueous urea solution is generally made up of 32.5% urea and 67.5% water.

An important key to minimizing emissions from internal combustion engines is to bring the exhaust aftertreatment components to an operating temperature as quickly as possible after starting the internal combustion engine and then to operate them continuously in this temperature range in order to enable the most efficient possible exhaust aftertreatment.

In-engine heating measures such as retarding the ignition angle or the injection timing, late post-injection of fuel or lambda-split operation of the internal combustion engine are known from the prior art, in which a deterioration in the thermal efficiency of the internal combustion engine is deliberately accepted is used to introduce additional energy into the exhaust system and to achieve higher exhaust gas temperatures.

In addition, electric heating elements and exhaust gas burners are known, with which the exhaust gas flow or a component in the exhaust system can be heated. However, electrical heating elements and exhaust gas burners have the disadvantage that additional energy is required for heating. In addition, such engine-external heating measures have the disadvantage that although they increase the exhaust gas temperature, they neither lead to a reduction in the raw exhaust gas emissions nor can they be used to propel the motor vehicle.

From the DE 10 2008 032 601 A1 an exhaust gas aftertreatment system for an internal combustion engine is known, in which an oxidation catalytic converter, downstream of the oxidation catalytic converter a NOx storage catalytic converter, downstream of the NOx storage catalytic converter an SCR catalytic converter and further downstream a particle filter are arranged. In this case, downstream of the SCR catalytic converter and upstream of the particle filter, an introduction point for a hot exhaust gas from an exhaust gas burner is provided in order to heat the particle filter to its regeneration temperature.

the DE 10 2016 205 182 A1 discloses an exhaust aftertreatment system for an internal combustion engine with a catalytically coated particulate filter and a NOx storage catalyst, with an exhaust gas burner being provided upstream of the NOx storage catalyst, which is operated with a substoichiometric combustion air ratio in order to heat up the exhaust gas and simultaneously regenerate the NOx storage catalyst with the to allow unburned hydrocarbons from the burner exhaust gas.

the EP 1 469 173 B1 discloses an exhaust gas aftertreatment system for an internal combustion engine, in which an oxidation catalytic converter is arranged in the flow direction of an exhaust gas through the exhaust gas aftertreatment system, an SCR catalytic converter is arranged downstream of the oxidation catalytic converter and a particle filter is arranged further downstream. A heat exchanger for cooling the exhaust gas flow is provided downstream of the oxidation catalytic converter and upstream of the SCR catalytic converter, and a heating element is provided downstream of the SCR catalytic converter and upstream of the particulate filter in order to heat the exhaust gas flow to a regeneration temperature before it enters the particulate filter.

From the DE 101 39 526 A1 a motor vehicle with an internal combustion engine and a turbocharger is known. The turbocharger is provided with an electrical machine that can be operated either as an electric motor or as a generator. The turbine of the turbocharger can be supplied with exhaust gas from a gas generation unit, for example from a burner, for driving the turbine and thus to drive the electrical machine as a generator to generate electricity when the combustion engine is switched off. A fresh air bypass can connect the outlet side of the compressor to the gas inlet side of the burner. A heat exchanger is preferably provided between the exhaust gases of the turbine and the fresh air in the fresh air bypass.

DE 10 2014 017 631 A1 describes an internal combustion engine with an exhaust gas turbocharger, the exhaust gas turbocharger being equipped with a first electric machine that can be operated as a motor and as a generator for driving or for driving support of the exhaust gas turbocharger. The internal combustion engine is operatively connected to a low-voltage on-board network of a motor vehicle, in which a second electric machine that can be operated as a motor and as a generator and that can be coupled or coupled to the crankshaft in a torque-transmitting manner, and an electrical energy store for supplying the electrical consumers arranged in the low-voltage on-board network are provided.

An internal combustion engine with an exhaust gas turbocharger and an exhaust gas aftertreatment system is known from US 2012/0 042 632 A1. A switchable bypass is provided on the turbocharger, with which an exhaust gas flow from the internal combustion engine can be routed past the turbine of the exhaust gas turbocharger. Furthermore, a fuel injection valve is provided on an exhaust gas duct of the internal combustion engine downstream of an outlet of the internal combustion engine and upstream of the bypass, with which fuel injection valve fuel can be injected into the exhaust system.

EP 2 535 539 A1 discloses an internal combustion engine for a boat, in which a combustion chamber is arranged in the exhaust system downstream of an outlet of the internal combustion engine and upstream of a turbine of an exhaust gas turbocharger, in which fuel can be burned in addition to the combustion chambers of the internal combustion engine.

The object of the invention is now to reduce the exhaust gas emissions of the internal combustion engine, the energy expended to reduce the exhaust gas emissions being able to be used at least in part.

According to the invention, this object is achieved by an internal combustion engine with a crankshaft and at least one combustion chamber, the intake of the internal combustion engine being connected to an intake tract and the exhaust of the internal combustion engine being connected to an exhaust system. The internal combustion engine has an exhaust gas turbocharger with a compressor and a turbine, which are connected to one another by a shaft. Provision is made for a combustion chamber to be arranged in the flow direction of an exhaust gas from the internal combustion engine through the exhaust system downstream of the outlet of the internal combustion engine and upstream of the turbine of the exhaust gas turbocharger. Provision is also made for the drive shaft of the exhaust gas turbocharger to be connected at least indirectly to the crankshaft of the internal combustion engine. At least one exhaust gas aftertreatment component for exhaust gas aftertreatment of an exhaust gas of the internal combustion engine is arranged in the exhaust system downstream of the turbine. In the case of the internal combustion engine according to the invention, it is possible in an advantageous manner to implement a heating measure as close as possible to the exhaust gas aftertreatment components in order to minimize the thermal inertia compared to internal engine heating measures. In addition, the waste heat losses through the walls of the exhaust gas duct are reduced. The heat generated in the combustion chamber can also be used to drive the turbine of the exhaust gas duct, as a result of which at least part of this heat can be used. In addition, internal engine heating measures to heat up the exhaust gas aftertreatment components, which are associated with increased fuel consumption and increased raw emissions from the internal combustion engine, can be omitted.

Advantageous further developments and non-trivial improvements of the internal combustion engine specified in the independent claim are provided by the features listed in the dependent claims.

In a preferred embodiment of the invention, it is provided that the drive shaft of the exhaust gas turbocharger is connected to an electrical machine, via which the compressor of the exhaust gas turbocharger can be driven independently of the exhaust gas flow of the internal combustion engine. With an electric machine on the drive shaft, the turbine of the exhaust gas turbocharger can be used to generate electrical energy. This energy can either be used directly or stored in a battery.

As a result, an alternator connected to the internal combustion engine can be relieved, which increases the efficiency of the internal combustion engine and thus improves fuel efficiency. By temporarily storing the energy, there is also the possibility of using this energy to increase the power and/or the torque of the internal combustion engine if required.

In a preferred embodiment of the invention it is provided that the shaft of the exhaust gas turbocharger is mechanically connected to the crankshaft of the internal combustion engine via a through drive. The waste heat from the combustion chamber can be used by a mechanical through drive to drive the crankshaft of the combustion engine via the drive shaft of the turbocharger and the through drive. As a result, the power at the crankshaft can be increased, which increases the efficiency of the combustion engine. The load point of the internal combustion engine can be shifted in the direction of a load point with lower raw emissions.

Alternatively, it is advantageously provided that the electric machine is driven by the turbine of the exhaust gas turbocharger and generates electric power, which is transmitted to an electric drive motor on the crankshaft. As an alternative to a mechanical through drive, an electrical connection can also be provided between the electric machine on the drive shaft of the exhaust gas turbocharger and an electric drive motor, which can be coupled to the crankshaft of the internal combustion engine. In this way, the waste heat from the combustion chamber can also be used to forward the energy obtained via the turbine to the crankshaft and thus to use it to drive a motor vehicle.

In an embodiment of the internal combustion engine that does not belong to the invention, it is provided that a supply line is provided, with which the intake tract is connected to the combustion chamber in the exhaust system downstream of the compressor. A partial quantity of the fresh air compressed by the compressor of the exhaust gas turbocharger can be branched off from the intake duct and fed to the combustion chamber through a supply line. As a result, a simple and inexpensive air supply to the combustion chamber is possible when the internal combustion engine is operated with a stoichiometric or super-stoichiometric combustion air ratio. This is particularly useful in Otto engines in order to reduce raw emissions and to enable maximum-efficiency after-treatment of the exhaust gases from the internal combustion engine.

A supply valve can be arranged in the supply line, via which the supply of fresh air to the combustion chamber can be controlled. The air supply to the combustion chamber can be controlled in a simple manner by means of a supply valve. In addition, it is possible to prevent exhaust gas from the combustion chambers of the internal combustion engine or from the combustion chamber from flowing back into the intake duct in an uncontrolled manner. Alternatively, the supply valve can be used for targeted exhaust gas recirculation in order to reduce raw emissions in the combustion engine's combustion chambers.

According to the invention, a secondary air compressor is advantageously provided, which is connected to the combustion chamber in the exhaust system via a secondary air line. As an alternative to an air supply from the intake tract, it is possible to use an external secondary air pump, with which the combustion chamber can be supplied with fresh air regardless of the operating state of the combustion engine. This is particularly advantageous at low speeds and low loads on the internal combustion engine, because in this operating state the turbine only feeds little power into the drive shaft and only little boost pressure is built up via the compressor of the exhaust gas turbocharger.

In an advantageous embodiment of the invention, it is provided that the secondary air compressor is designed as a mechanically driven additional compressor, which is driven by the internal combustion engine by a traction mechanism, in particular a chain or a belt. A mechanical drive of the secondary air compressor provides a simple and cost-effective option for the drive.

Alternatively, a further advantageous embodiment of the invention provides that the secondary air compressor is designed as an electric auxiliary compressor. With an electric drive, the secondary air compressor can be operated independently of the operating situation of the internal combustion engine, which makes it easier to control the amount of secondary air.

It is particularly preferred if a secondary air valve is arranged in the secondary air line, via which the fresh air supply to the combustion chamber can be controlled. The supply of fresh air to the combustion chamber can be controlled in a simple manner by a secondary air valve. In addition, exhaust gas from the combustion chambers of the internal combustion engine or from the combustion chamber can be prevented from escaping into the environment in an uncontrolled manner. In this case, the secondary air valve can in particular comprise a non-return valve in order to allow a flow of fresh air in the direction of the combustion chamber, but to prevent an exhaust gas flow counter to this flow.

• - Einbringen eines Brennstoffs in die Brennkammer,
• - Zufuhr von Sekundärluft in die Brennkammer, wobei
• - der Brennstoff mit dem Sauerstoff aus der Sekundärluft exotherm in der Brennkammer umgesetzt wird,
• - Beaufschlagen der Turbine des Abgasturboladers mit dem heißen Abgas aus der Brennkammer, wobei die Turbine die Antriebswelle antreibt und wobei
• - die mindestens eine Abgasnachbehandlungskomponente durch das heiße Abgas aus der Brennkammer auf eine Betriebstemperatur aufgeheizt oder auf dieser Betriebstemperatur gehalten wird.

According to the invention, a method for operating an internal combustion engine according to the invention is proposed, which comprises the following steps.

• - introducing a fuel into the combustion chamber,
• - Supply of secondary air into the combustion chamber, where
• - the fuel is reacted exothermically with the oxygen from the secondary air in the combustion chamber,
• - Applying the hot exhaust gas from the combustion chamber to the turbine of the exhaust gas turbocharger, the turbine driving the drive shaft and wherein
• - The at least one exhaust gas aftertreatment component is heated to an operating temperature by the hot exhaust gas from the combustion chamber or is kept at this operating temperature.

The method according to the invention makes it possible to heat the exhaust gas aftertreatment components to an operating temperature shortly after starting the internal combustion engine and to always keep these exhaust gas aftertreatment components at this operating temperature during further operation of the internal combustion engine. The waste heat from the combustion chamber can be used to drive the turbine of the exhaust gas turbocharger and thus recover at least part of the additional energy expended.

In an advantageous improvement of this method, it is provided that the drive shaft is connected at least indirectly to the crankshaft of the internal combustion engine, with the hot exhaust gas from the combustion chamber driving the crankshaft at least indirectly. As a result, the additional energy that is released during the combustion of the fuel in the combustion chamber can be transferred to the crankshaft of the internal combustion engine and thus used to drive a motor vehicle. Alternatively, the energy from the combustion chamber can be absorbed by the electric machine and temporarily stored in a battery. If necessary, this energy can then be delivered to an electric drive motor coupled to the crankshaft in order to correspondingly increase the power and/or the torque of the internal combustion engine.

In a variant of the method not belonging to the invention, it is provided that the internal combustion engine is operated with a superstoichiometric combustion air ratio, the oxygen required for combustion of the fuel introduced into the combustion chamber being supplied to the combustion chamber via the superstoichiometric exhaust gas.

An oxygen-rich exhaust gas can be supplied to the combustion chamber in a simple manner by means of an over-stoichiometric combustion air ratio, with which the fuel can be exothermically converted. This is particularly easy in a diesel engine due to the principle-related excess air. Alternatively, it is also possible in a gasoline engine to carry out the combustion of the fuel in the combustion chambers of the combustion engine with a super-stoichiometric combustion air ratio, with a stoichiometric exhaust gas preferably being established downstream of the combustion chamber in order to achieve maximum-efficiency exhaust gas aftertreatment by the exhaust gas aftertreatment components downstream of the turbine of the exhaust gas turbocharger enable.

In a further variant not belonging to the invention it is provided that the intake air is compressed by the compressor and the compressed intake air is supplied to the combustion chamber via the supply line. In this case, the internal combustion engine can be operated by heating the exhaust gas through the combustion chamber without internal engine heating measures, as a result of which the efficiency can be optimized and/or the untreated emissions of the internal combustion engine can be minimized.

According to the invention it is provided that secondary air is compressed by a secondary air compressor, the compressed secondary air being fed to the combustion chamber via a secondary air line. By supplying air to the combustion chamber via a secondary air compressor, the amount of fresh air and thus the combustion air ratio in the combustion chamber can be adjusted independently of the operating situation of the internal combustion engine. In this way, an adequate supply of air can also be ensured when the compressor only builds up a low charge pressure and a supply of fresh air via a supply line from the intake tract is not possible.

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

• 1 ein erstes Ausführungsbeispiel eines Verbrennungsmotors mit einem Ansaugtrakt und einer Abgasanlage;
• 2 ein Ausführungsbeispiel eines nicht zur Erfindung gehörenden Verbrennungsmotors mit einem Ansaugtrakt und einer Abgasanlage, wobei die Ansaugleitung mit der Brennkammer über eine Versorgungsleitung verbunden ist;
• 3 ein Ausführungsbeispiel eines erfindungsgemäßen Verbrennungsmotors mit einem Ansaugtrakt und einer Abgasanlage, wobei eine Sekundärluftpumpe zur Luftversorgung der Brennkammer vorgesehen ist; und
• 4 ein Ablaufdiagramm zur Durchführung eines erfindungsgemäßen Verfahrens zum Betreiben eines Verbrennungsmotors.

The invention is explained below in exemplary embodiments with reference to the associated drawings. Show it:

• 1 a first embodiment of an internal combustion engine with an intake tract and an exhaust system;
• 2 an embodiment of an internal combustion engine not belonging to the invention with an intake tract and an exhaust system, wherein the intake line is connected to the combustion chamber via a supply line;
• 3 an embodiment of an internal combustion engine according to the invention with an intake tract and an exhaust system, wherein a secondary air pump is provided for supplying air to the combustion chamber; and
• 4 a flowchart for carrying out a method according to the invention for operating an internal combustion engine.

1 shows the schematic representation of an internal combustion engine 10 with an intake tract 20 and an exhaust system 40. In this exemplary embodiment, the internal combustion engine 10 is a direct-injection diesel engine and has a crankshaft 14 and a plurality of combustion chambers 12. A fuel injector for injecting a fuel into the respective combustion chamber 12 is arranged on each of the combustion chambers 12 . The internal combustion engine 10 is connected to an intake tract 20 at its inlet 16 and to an exhaust system 40 at its outlet 18 . The internal combustion engine 10 can have a high-pressure exhaust gas recirculation, not shown, with a high-pressure exhaust gas recirculation valve, via which an exhaust gas of 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 intake tract 20 to the combustion chambers 12 or from the combustion chambers 12 to the exhaust system 40 can be opened or closed.

The intake tract 20 comprises an intake duct 22, in which, in the flow direction of fresh air through the intake duct 22, is an air filter 24, downstream of the air filter 24 an air mass meter 26, in particular a hot-film air mass meter, downstream of the air mass meter 26 a compressor 30 of an exhaust gas turbocharger 28 and further downstream a charge air cooler 32 are arranged. The air mass meter 26 can also be arranged in a filter housing of the air filter 24, so that the air filter 24 and the air mass meter 26 form an assembly.

Exhaust system 40 comprises an exhaust gas duct 42, in which, in the direction of flow of an exhaust gas from internal combustion engine 10 through exhaust gas duct 42, is a combustion chamber 44, downstream of combustion chamber 44 a turbine 50 of exhaust gas turbocharger 28, and further downstream a plurality of exhaust gas aftertreatment components 52, 54, 56 for exhaust gas aftertreatment of the exhaust gases of the Internal combustion engine 10 are arranged. The turbine 50 is connected to the compressor 30 of the exhaust gas turbocharger 28 via a drive shaft 36 . Furthermore, an electric machine 34 is arranged on the drive shaft 36, which can drive the compressor 30 independently of the exhaust gas flow of the internal combustion engine 10 or is rotated as a generator by the turbine 50 and thus converts the mechanical energy of the exhaust gas turbocharger 28 into electrical energy. The drive shaft 36 is mechanically connected to the crankshaft 14 of the internal combustion engine 10 via a through drive 38 so that the drive shaft 36 can transfer energy to the crankshaft 14 and can thus be used to drive a motor vehicle or a work machine. Alternatively or additionally, an electric drive motor 72 can be provided on the crankshaft 14 , which is supplied with electric power by the electric machine 34 on the drive shaft 36 .

A plurality of exhaust gas aftertreatment components 52, 54, 56 are arranged downstream of the turbine 50 of the exhaust gas turbocharger 28. A catalytic converter 52 , in particular an oxidation catalytic converter or a NOx storage catalytic converter, is arranged as the first exhaust gas aftertreatment component 52 in the direction of flow downstream of the turbine 50 . A metering module 58 is provided downstream of the catalytic converter 52 and can be used to meter a reducing agent 70 , in particular an aqueous urea solution, into the exhaust gas duct 42 . An exhaust gas mixer 76 is provided downstream of the dosing module 58 in order to achieve better mixing of the reducing agent with the exhaust gas flow of the internal combustion engine 10 . A particle filter 54 with a coating for the selective, catalytic reduction of nitrogen oxides is provided downstream of the exhaust gas mixer, which has the function of an SCR catalytic converter 56 . Alternatively, an SCR catalytic converter 56 and an uncoated particle filter 54 can also be provided downstream of the dosing module 58 .

Internal combustion engine 10 is connected to an engine control unit 80, which is connected via signal lines (not shown) to a temperature sensor, an NOx sensor, a differential pressure sensor, to the fuel injectors of internal combustion engine 10 and to dosing module 58 and combustion chamber 44.

The injection quantity and the injection time of the fuel into the combustion chambers 12 of the internal combustion engine 10, the injection quantity into the combustion chamber 44 and the metering of the reducing agent 70 for the selective catalytic reduction of nitrogen oxides into the exhaust gas duct 42 are controlled by this engine control unit 80. Furthermore, the combustion of the fuel in the combustor chamber 44 can be activated or deactivated by the engine controller 80 . Nitrogen monoxide (NO) can be oxidized to nitrogen dioxide (NO ₂ ) by the catalytic converter 52, so that the ratio of nitrogen monoxide (NO) to nitrogen dioxide (NO ₂ ) can be changed before entering the SCR catalytic converter 56 or the coated particulate filter 54 in order to to optimize the efficiency of selective catalytic reduction.

Alternatively, the internal combustion engine 10 can also be designed as an Otto engine, in which case the catalytic converter 52 is preferably designed as a three-way catalytic converter 52 . Furthermore, the particle filter 54 is preferably designed as an uncoated particle filter or as a four-way catalytic converter with a three-way catalytically active coating. The dosing module 58 is omitted in this exemplary embodiment.

In 2 an exemplary embodiment of an internal combustion engine 10 not belonging to the invention is shown. With essentially the same structure as 1 A supply line 46 is additionally provided in this exemplary embodiment, which connects the intake channel 22 downstream of the compressor 30 of the exhaust gas turbocharger 28 to the combustion chamber 44 in the exhaust system 40 . A supply valve 48 is provided in the supply line 46 with which the supply of fresh air into the combustion chamber 44 can be controlled. The supply valve 48 also prevents exhaust gas from the combustion chamber 44 from flowing back into the intake tract 20 in an uncontrolled manner. In this case, the supply valve 48 can also be used as an exhaust gas recirculation valve in order to reduce the untreated emissions of the internal combustion engine 10 . In addition, an oxidation catalytic converter 52 or a NOx storage catalytic converter is provided downstream of the turbine 50 of the exhaust gas turbocharger 28 , a particle filter 54 is provided downstream of the oxidation catalytic converter 52 or the NOx storage catalytic converter and further downstream an SCR catalytic converter 56 is provided. A metering module 58 is arranged downstream of the particle filter 54 and upstream of the SCR catalytic converter 56 , with which a reducing agent 70 can be metered into the exhaust gas duct 42 upstream of the SCR catalytic converter 56 . An exhaust gas mixer 76 can be connected downstream of the metering module 58 in order to improve the mixing of the exhaust gas flow with the metered-in reducing agent 70 .

In 3 an exemplary embodiment of an internal combustion engine 10 according to the invention is shown. With essentially the same structure as 1 an additional secondary air compressor 60 for supplying air to the combustion chamber 44 is provided in this exemplary embodiment. The secondary air compressor 60 is connected to an inlet of the combustion chamber 44 via a secondary air line 66, a secondary air valve 68 being provided in the secondary air line 66, with which the air supply to the combustion chamber 44 is controlled. Secondary air valve 68 also prevents exhaust gas from flowing out of combustion chamber 44 into the environment in an uncontrolled manner. The secondary air compressor 60 is preferably designed as an electrically driven secondary air compressor 62 . Alternatively, the secondary air compressor 60 can also be designed as a mechanical additional compressor 64, the mechanical additional compressor being connected to the internal combustion engine 10 by a traction mechanism, in particular by a belt or a chain, and being driven by the latter. This embodiment also differs in that downstream of the turbine 50 of the exhaust gas turbocharger 28 there is a catalytic converter 52, in particular an oxidation catalytic converter or a NOx storage catalytic converter, downstream of the catalytic converter 52 a particle filter 54 with a coating for the selective, catalytic reduction of nitrogen oxides and further downstream an SCR -Catalyst 56 are arranged. A first dosing module 58 for dosing in a reducing agent 70 is provided downstream of the catalytic converter 52 and upstream of the particle filter 54, and a first exhaust gas mixer 76 is connected downstream of said dosing module. A second dosing module 74 is provided downstream of the particle filter 54 and upstream of the SCR catalytic converter 56, which is followed by a second exhaust gas mixer 78.

Alternatively, the exhaust gas mixers 76, 78 can also be omitted in all of the exemplary embodiments, provided that sufficient mixing of the reducing agent 70 and the exhaust gas of the internal combustion engine 10 is also achieved without the respective exhaust gas mixer 76, 78.

In 4 a flowchart for a method according to the invention for operating such an internal combustion engine 10 is shown. In a first method step <100>, a fuel, in particular the fuel of internal combustion engine 10, and oxygen-rich exhaust gas or fresh air are introduced into combustion chamber 44. In a second method step <110>, this fuel-air mixture is ignited and initiates combustion in the combustion chamber 44 in a method step <120>. In this case, continuous combustion is preferably provided in order to ensure a uniform input of energy into the exhaust system 20 and to heat the exhaust gas aftertreatment components 52, 54, 56 to an operating temperature as quickly as possible in a method step <140>. The hot exhaust gas from the combustion chamber 44 drives the turbine 50 of the exhaust gas turbocharger 28 in a method step <150> in addition to the exhaust gas flow of the internal combustion engine 10, whereby the waste heat from the combustion chamber 44 can be recovered at least partially.

Reference List

10

combustion engine

12

combustion chamber

14

crankshaft

16

inlet

18

outlet

20

intake tract

22

intake duct

24

air filter

26

mass airflow meter

28

exhaust gas turbocharger

30

compressor

32

intercooler

34

electric machine

36

drive shaft

38

through drive

40

exhaust system

42

exhaust duct

44

combustion chamber

46

supply line

48

Supply valve / check valve

50

turbine

52

Oxidation catalytic converter / NOx storage catalytic converter / three-way catalytic converter

54

particle filter

56

SCR catalytic converter

58

dosing element

60

secondary air compressor

62

electric auxiliary compressor

64

mechanical booster

66

secondary air line

68

secondary air valve

70

reducing agent

72

electric drive motor

74

second dosing module

76

exhaust mixer

78

exhaust mixer

80

control unit

Claims (9)

Internal combustion engine (10) with a crankshaft (14) and at least one combustion chamber (12), wherein the internal combustion engine (10) is connected with its inlet (16) to an intake tract (20), and wherein the internal combustion engine (10) with its outlet ( 18) is connected to an exhaust system (40), and to an exhaust gas turbocharger (28) with a compressor (30) and a turbine (50), which are connected to one another by a drive shaft (36), wherein in the direction of flow of an exhaust gas from the internal combustion engine ( 10) a combustion chamber (44) is arranged through the exhaust system (40) downstream of the outlet (18) of the internal combustion engine (10) and upstream of the turbine (50) of the exhaust gas turbocharger (28), characterized in that the drive shaft (36) of the exhaust gas turbocharger (28) can be connected at least indirectly to the crankshaft (14) of the internal combustion engine (10), wherein in the exhaust system (40) downstream of the turbine (50) at least one exhaust gas aftertreatment component (52, 54, 56) for exhaust gas aftertreatment Treatment of an exhaust gas of the internal combustion engine (10) is arranged, and wherein a secondary air compressor (60) is provided, which is connected to the combustion chamber (44) via a secondary air line (66). Internal combustion engine (10) after claim 1 , characterized in that the drive shaft (36) of the exhaust gas turbocharger (28) is connected to an electrical machine (34) via which the compressor (30) can be driven independently of the exhaust gas flow of the internal combustion engine (10). Internal combustion engine (10) after claim 1 or 2 , characterized in that the shaft (36) of the exhaust gas turbocharger (28) via a through drive (38) is mechanically connected to the crankshaft (14). Internal combustion engine (10) after claim 2 , characterized in that the electric machine (34) generates electric power, which is transmitted to an electric drive motor (72) on the crankshaft (14). Internal combustion engine (10) according to one of Claims 1 until 4 , characterized in that the secondary air compressor (60) is designed as a mechanical additional compressor (64) which is driven by the internal combustion engine (10) by means of a traction device. Internal combustion engine (10) according to one of Claims 1 until 4 , characterized in that the secondary air compressor (60) is designed as an electric auxiliary compressor (62). Internal combustion engine (10) according to one of Claims 1 until 6 , characterized in that a secondary air valve (68) is arranged in the secondary air line (66). Method for operating an internal combustion engine (10) according to one of Claims 1 until 7 , comprising the following steps: - introducing a fuel into the combustion chamber (44), - supplying secondary air into the combustion chamber (44), - secondary air is compressed by a secondary air compressor (60), the compressed secondary air being fed to the combustion chamber (44) via a secondary air line (66), wherein - the fuel is reacted exothermically with the oxygen from the secondary air in the combustion chamber (44), - Applying the hot exhaust gas from the combustion chamber (44) to the turbine (50) of the exhaust gas turbocharger (28), the turbine (50) driving the drive shaft (36), and wherein - the at least one exhaust gas aftertreatment component (52, 54, 56) is heated to an operating temperature or maintained at this operating temperature by the hot exhaust gas from the combustion chamber (44). Method for operating an internal combustion engine (10). claim 8 , characterized in that the drive shaft (36) is at least indirectly connected to the crankshaft (14) of the internal combustion engine (10), the hot exhaust gas from the combustion chamber (44) at least indirectly driving the crankshaft (14).

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