DE102020116169B4 - Method for operating an internal combustion engine and motor vehicle with an internal combustion engine - Google Patents

Abstract

Method for operating an internal combustion engine (10) having at least one combustion chamber (12), wherein the internal combustion engine (10) is connected by its outlet (18) to an exhaust system (20), and the internal combustion engine (10) is connected to at least one auxiliary unit (52, 56, 72), wherein the power of the auxiliary unit (52, 56, 72) is reduced in the event of a dynamic load request to the internal combustion engine (10) in order to reduce the overall additional engine load for the internal combustion engine (10) and thus to reduce the raw emissions of the internal combustion engine (10), characterized in that the power of all auxiliary units (52, 56, 72) is reduced or all auxiliary units (52, 56, 72) are switched off.

Description

The invention relates to a method for operating an internal combustion engine and to a motor vehicle with an internal combustion engine for carrying out such a method according to the preamble of the independent patent claims.

Current emissions legislation, which will become increasingly stricter in the future, places high demands on raw engine emissions and exhaust gas aftertreatment in internal combustion engines. The demands for further reduced fuel consumption and the further tightening of emissions standards regarding permissible nitrogen oxide emissions pose challenges for engine developers. In gasoline engines, exhaust gas purification is achieved in the usual way via a three-way catalytic converter, as well as additional catalysts upstream and downstream of the three-way catalytic converter. Diesel engines currently use exhaust gas 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 possibly additional catalysts. To meet the stringent requirements for minimal nitrogen oxide emissions, exhaust aftertreatment systems are known that feature two SCR catalysts connected in series, with a metering element for metering a reducing agent upstream of each SCR catalyst. The reducing agent used is preferably a synthetic, aqueous urea solution, which is mixed with the hot exhaust stream in a mixing device upstream of the SCR catalyst. This mixing heats the aqueous urea solution, releasing ammonia into the exhaust duct. A commercially available aqueous urea solution generally consists of 32.5% urea and 67.5% water.

With the introduction of the EU6 legislation, a limit value for the number of particles is prescribed for gasoline engines, which in many cases requires the use of a gasoline particulate filter. Such soot particles are formed particularly after a cold start of the internal combustion engine due to incomplete combustion in combination with a substoichiometric combustion air ratio and cold cylinder walls during the cold start. The cold start phase is therefore crucial for compliance with the legally prescribed particle limits. During driving, such a gasoline particulate filter becomes further loaded with soot. To prevent the exhaust back pressure from increasing too much, this gasoline particulate filter must be regenerated continuously or periodically. The increase in exhaust back pressure can lead to increased consumption of the internal combustion engine, a loss of power and a deterioration in smooth running, even leading to misfiring. In order to achieve thermal oxidation of the soot trapped in the gasoline particulate filter with oxygen, a sufficiently high temperature level in conjunction with the simultaneous presence of oxygen in the exhaust system of the gasoline engine is necessary. Since modern gasoline engines are typically operated without excess oxygen and with a stoichiometric combustion air ratio (λ=1), additional measures are required. These measures include, for example, increasing the temperature by adjusting the ignition timing, temporarily leaning the gasoline engine, injecting secondary air into the exhaust system, or a combination of these measures. To date, retarding the ignition timing in combination with leaning the gasoline engine has been preferred, as this method requires no additional components and can deliver a sufficient amount of oxygen at most operating points of the gasoline engine.

Furthermore, electrically heatable 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.

From the EP 1 239 127 A1 A method for heating an electrically heatable catalyst during deceleration of a motor vehicle is known. The electrically heatable catalyst is electrically heated by a starter-generator unit during deceleration of the motor vehicle in order to keep the temperature of the catalyst above a light-off temperature of the catalyst. The mechanical energy during deceleration of the motor vehicle is converted into electrical energy by the starter-generator unit, and this energy is used to heat the electrically heatable catalyst.

The DE 197 40 971 A1 discloses a power supply control device for an electrically heated catalyst having an electric generator driven by an internal combustion engine, a battery, an electric heating device for heating a catalyst arranged in an exhaust system of the internal combustion engine, a battery charging circuit for connecting the battery to the generator and supplying an electric current for charging the battery, a catalyst heating circuit for directly connecting the heating device to the generator and An electric current is supplied from the generator to the heater to raise the temperature of the catalyst to an operating temperature. A temperature maintenance circuit is also provided for connecting the heater to the battery and supplying an electric current from the battery to the heater to maintain the temperature of the catalyst above the operating temperature. The power supply control device switches off the battery charging circuit and the temperature maintenance circuit and switches on the catalyst heating circuit when the internal combustion engine has been started, so that the catalyst is heated to the operating temperature. A second power supply control device switches off the catalyst heating circuit and switches on the battery charging circuit and the temperature maintenance circuit when the temperature of the catalyst has reached the operating temperature. This charges the battery while maintaining the catalyst at a temperature higher than the operating temperature.

From the DE 10 2016 122 304 A1 A method for heating an electrically heatable catalyst in an exhaust duct of a motor vehicle with an internal combustion engine is known. To heat the catalyst before the internal combustion engine starts, the catalyst is electrically heated before the engine starts, enabling efficient exhaust gas aftertreatment as soon as the engine starts. Following an electrical preheating phase after the engine starts, the catalyst is further heated through a combined electrical and chemical heating process resulting from the exothermic conversion of unburned fuel components on a catalytically active surface of the electrically heatable catalyst.

The DE 10 2005 024 411 B4 discloses a drive arrangement for a motor vehicle with an internal combustion engine that is drivingly connected to a generator and an electric motor, wherein the electric motor can be coupled and disconnected from the internal combustion engine by means of a switchable clutch, wherein the electric motor is drivingly connected to at least one auxiliary unit, in particular an air conditioning compressor, and wherein the drive arrangement has a regulating/control device that is connected to the internal combustion engine, the electric motor, the generator, and the clutch in such a way that, depending on predeterminable driving and operating parameters of the motor vehicle, the clutch can be opened or closed, so that the at least one auxiliary unit is driven by the internal combustion engine when the clutch is closed and by the electric motor when the clutch is open, wherein the electric motor is electrically connected, on the one hand, to the generator and, on the other hand, to an electrical energy storage device, so that the electric motor can be supplied with energy individually or simultaneously via the generator depending on predeterminable energetic parameters, wherein the electrical energy storage device is also connected to the regulating/control device.

WO 2006/108 521 A1 discloses a method for coordinating the actuation of at least one auxiliary unit of a motor vehicle that can be driven by a main unit of a motor vehicle. It is provided that a query unit queries limit values for the actuation of at least one auxiliary unit and an actual value of resources of the at least one auxiliary unit, and a decision unit controls the actuation of the at least one auxiliary unit at least as a function of its limit values and its actual value. Furthermore, an auxiliary unit for a motor vehicle that can be driven by a main unit of the motor vehicle and comprises a detection unit for detecting an actual value of a reserve of resources of the auxiliary unit is specified.

DE 102 32 354 A1 describes a method and a device for controlling the drive unit of a motor vehicle, which enables the central coordination of various reserve torque requirements. A reserve is created for an output variable of the drive unit. Various reserve requirements of different physical significance are compared with each other, and a resulting reserve requirement is created based on the comparison.

1. 1. Erfassen einer Abweichung eines momentan vorliegenden Regelistwerts von einem Idealwert des Regelistwert, der bei idealen Einflussgrößen vorliegen müsste,
2. 2. Verschiebung zumindest eines ersten momentanen Regelsollwerts einer Einflussgröße des Verbrennungsmotors zu einem zweiten Regelsollwert, bei dem zu erwarten ist, dass der Kraftstoffverbrauch und die Schadstoffemission unterhalb jeweiliger Grenzwerte liegen, bis der Idealwert wieder vorliegt.

From the DE 10 2018 220 485 A1 A method for controlling an internal combustion engine in a motor vehicle is known, with which fuel consumption and pollutant emissions can be adjusted to influencing factors in order to achieve optimal efficiency despite changing influencing factors. The method comprises the following steps:

1. 1. Detection of a deviation of a currently existing control actual value from an ideal value of the control actual value, which would have to be present with ideal influencing variables,
2. 2. Shifting at least a first instantaneous control setpoint of an influencing variable of the combustion engine to a second control setpoint at which it is expected that fuel consumption and pollutant emissions will be below the respective limit values until the ideal value is reached again.

The DE 198 38 333 A1 discloses a computer system with at least one processor and at least one memory for controlling a drive unit of a vehicle. The vehicle is viewed as an overall system consisting of functional units, simultaneously representing a first component. The overall system, consisting of functional units, is divided into various predeterminable components. The drive unit of the vehicle is defined as one component. The components and their interfaces, via which data is exchanged between the components, are programmed or stored in the at least one memory in the computer system. The drive unit is then controlled depending on the predefined components and/or the data exchanged between the components at the interfaces.

From the DE 10 2008 061 885 A1 An internal combustion engine for a motor vehicle with an accessory drive is known, via which at least one accessory can be operated and which is connected to a crankshaft. A continuously variable transmission is provided between the crankshaft and the accessory drive in order to variably translate a speed of the crankshaft into a speed suitable for the at least one accessory. Furthermore, the continuously variable transmission is designed such that an eccentric component is mounted on a drive shaft connected to the crankshaft, which can be rotated relative to the crankshaft and to which a plurality of crank elements are articulated. The crank elements each engage with their opposite ends directly or indirectly on stationary and rotatable wheels.

The DE 199 39 052 A1 describes a method for controlling an operating mode of at least one auxiliary unit in a motor vehicle, wherein the motor vehicle has a storage catalyst arranged in an exhaust duct of an internal combustion engine, and the internal combustion engine is set to a substoichiometric operating mode for regenerating the storage catalyst. It is provided that, at the start of regeneration, the operating mode of the at least one auxiliary unit is switched from a control mode to a regulated mode.

From the DE 10 2020 101 194 A1 A method for exhaust gas aftertreatment of an internal combustion engine with at least one combustion chamber is known. The internal combustion engine is connected via its exhaust to an exhaust system, in which an electrically heatable catalyst is arranged in the flow direction of an exhaust gas stream from the internal combustion engine, and at least one further catalyst is arranged downstream of the electrically heatable catalyst. The power of the electrically heatable catalyst is reduced when a dynamic load is applied to the internal combustion engine in order to reduce the overall engine load and thus reduce the engine's raw emissions.

The DE 10 2020 103 565 A1 Describes a method for exhaust gas aftertreatment of an internal combustion engine having at least one combustion chamber. The internal combustion engine is connected via its exhaust to an exhaust system in which an electrically heatable catalyst is arranged in the flow direction of an exhaust gas stream from the internal combustion engine, and at least one further catalyst is arranged downstream of the electrically heatable catalyst. The power of the electrically heatable catalyst is reduced when a dynamic load is required on the internal combustion engine in order to reduce the overall engine load when there is an unfavorable relationship between the additional power requirement and the raw emissions of the internal combustion engine. This is intended to reduce the raw emissions of the internal combustion engine.

From the DE 10 2016 001 792 A1 An exhaust aftertreatment system with a particulate collection system is known. To efficiently purify exhaust gases, the particulate collection system collects particles contained in an exhaust stream of an internal combustion engine. The particulate collection system includes a first particulate collection filter, a second particulate collection filter, a heating element for heating the second particulate collection filter, and a control element that selectively collects particles by the first particulate collection filter, collects particles by the first particulate collection filter and the second particulate collection filter, and heats the second particulate collection filter by the heating element.

• eine Massendurchflussrate eines Abgasstroms durch den Abgaskanal, eine Massengeschwindigkeit eines Abgasstroms, eine Strömungstemperatur stromaufwärts des mindestens einen elektrischen Heizers, eine Strömungstemperatur stromabwärts des mindestens einen elektrischen Heizers, eine Leistungseingabe an den mindestens einen elektrischen Heizer. Die Steuervorrichtung ist in der Lage, die Leistung des mindestens einen elektrischen Heizelements auf der Grundlage mindestens einer Eingabe zu modulieren.

Furthermore, US 2017/0 256 104 A1 describes a control system for an electrically heated exhaust system. The control system comprises at least one electric heater arranged in an exhaust duct and a control device adapted to receive at least one of the following input variables:

• a mass flow rate of an exhaust gas flow through the exhaust duct, a mass velocity of an exhaust gas flow, a flow temperature upstream of the at least one electric heater, a flow temperature downstream of the at least one electric heater, a power input to the at least one electric heater. The control device is capable of controlling the power of the at least one electric heater. ments based on at least one input.

The invention is based on the object of reducing the raw emissions of the combustion engine and improving the driving dynamics of a motor vehicle.

According to the invention, this object is achieved by a method for exhaust gas aftertreatment of an internal combustion engine having at least one combustion chamber. The internal combustion engine is connected to an exhaust system via its exhaust. The internal combustion engine is further connected to at least one auxiliary unit. It is provided that the power of the auxiliary unit is reduced in response to a dynamic load demand on the internal combustion engine in order to reduce the overall additional load for the internal combustion engine and thus reduce the raw emissions of the internal combustion engine. According to the invention, it is provided that the power of all auxiliary units is reduced or all auxiliary units are switched off.

The dynamic load demand on the combustion engine leads to an increase in raw emissions, particularly in raw nitrogen oxide emissions, which requires an increase in the exhaust gas recirculation rate to at least partially compensate for this increase. By simultaneously reducing the power of all auxiliary units, this dynamic increase in load for the combustion engine can be reduced, thereby limiting the increase in raw emissions of the combustion engine. By reducing the power of all auxiliary units or switching off all auxiliary units, the necessary additional power of the combustion engine can be reduced particularly efficiently during a dynamic load demand, thus dampening an increase in raw emissions. This is particularly helpful during a cold start phase of the combustion engine or after low-load operation, when the exhaust aftertreatment components have not yet reached their operating temperature and complete conversion of the harmful exhaust gas components by the catalytic converters cannot be guaranteed.

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

In a preferred embodiment of the invention, the auxiliary unit is shut down or mechanically decoupled from the combustion engine when the dynamic load demand exceeds a threshold. To improve the controllability of the method, it is advantageous if the method is only executed when a defined threshold for the dynamic load demand on the combustion engine is exceeded.

In an advantageous embodiment of the method, the dynamic load requirement exceeds an acceleration of the motor vehicle of at least 1 m/ ^s² . This requires a correspondingly large load jump for the combustion engine, which generally results in a deterioration in the engine's raw emissions in this operating state. In order to at least partially compensate for this deterioration in the engine's raw emissions, the power of the auxiliary units is reduced in order to limit the increase in total engine power for the drive and for the generation of electrical power for electrical auxiliary consumers. This can thus limit the increase in the engine's raw emissions. This leads to lower environmental emissions, particularly during a cold start phase of the combustion engine, since the conversion of pollutants in the exhaust stream by the exhaust gas aftertreatment components is still limited during a cold start phase. Alternatively, a limit value for a dynamic load requirement can be defined in the form of a combination of speed and acceleration. Since greater driving resistance occurs at higher speeds, a relatively higher power is required for the same acceleration at a higher speed. The limit value for the dynamic load requirement is considered to be a product of speed v and acceleration a, for which the following applies: v * a ≥ 3 m ² / s ³ .

In a preferred embodiment of the invention, the dynamic load requirement results from an uphill road with an average gradient of at least 5%. To negotiate an average gradient of 5%, a downhill force must be continuously overcome to at least maintain a constant speed. This leads to a high load requirement on the combustion engine. Such an incline therefore also leads to a dynamic load requirement and, associated with it, an increase in raw emissions, which can be minimized by simultaneously reducing the power of the auxiliary units.

In a preferred embodiment of the invention, it is provided that the power of the auxiliary units is reduced as soon as a control deviation of the exhaust gas recirculation rate due to a dynamic load requirement of >40%, preferably Typically >20%, particularly preferably >10%, is detected. Due to the dead time of the exhaust gas recirculation, a dynamic load demand on the combustion engine results in the current exhaust gas recirculation rate deviating from the emission-optimal exhaust gas recirculation rate at this load point of the combustion engine.

In a preferred embodiment of the invention, it is provided that the power of the auxiliary units is increased again when a control deviation of the exhaust gas recirculation rate of the internal combustion engine is less than 40%, preferably less than 20%, particularly preferably less than 10%.

It is particularly preferred if the increase in the power of the electrical auxiliary units or electrical auxiliary consumers occurs with a maximum gradient of 800 W/s, preferably with a maximum gradient of 500 W/s, particularly preferably with a maximum gradient of 300 W/s. This prevents the increase in the power of the auxiliary units or electrical auxiliary consumers from leading to a deterioration in the raw emissions, in particular the raw nitrogen oxide emissions, which cannot be compensated for by a corresponding adjustment of the exhaust gas recirculation rate.

A further aspect of the invention relates to an internal combustion engine having at least one combustion chamber, wherein the internal combustion engine is connected by its exhaust to an exhaust system. The internal combustion engine is mechanically or electrically connected to at least one auxiliary unit. The internal combustion engine is operatively connected to a control unit configured to carry out a method according to the invention for operating an internal combustion engine when a machine-readable program code is executed by the control unit. In such an internal combustion engine, pollutant emissions can be minimized by demand-based power control of the auxiliary units, since in the event of a dynamic load requirement, the necessary additional power of the internal combustion engine can be reduced by reducing the power of the auxiliary units. Thus, an increase in raw emissions can be limited, and efficient conversion of the pollutants in the exhaust stream can be ensured by appropriate exhaust gas aftertreatment components in the exhaust system.

In an advantageous embodiment of the internal combustion engine, the auxiliary unit is a generator, in particular a starter belt generator, or an air conditioning compressor. A generator or an air conditioning compressor are auxiliary units that have a comparatively high power output and are generally driven directly by the internal combustion engine. Therefore, reducing the power output of one of these auxiliary units leads particularly efficiently to a reduction in the power requirement of the internal combustion engine.

In a preferred embodiment of the internal combustion engine, the internal combustion engine can be connected to the auxiliary unit via a separable clutch, wherein the separable clutch is opened when a dynamic load is required on the internal combustion engine in order to reduce the required additional power. Such a clutch can be designed, for example, as a magnetic clutch and can break a mechanical connection between the internal combustion engine and the auxiliary unit when a dynamic load is required on the internal combustion engine.

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

• 1 ein bevorzugtes Ausführungsbeispiel für Kraftfahrzeug mit einem Verbrennungsmotor zur Durchführung eines erfindungsgemäßen Verfahren zur Abgasnachbehandlung;
• 2 ein weiteres Ausführungsbeispiel für ein Kraftfahrzeug mit einem Verbrennungsmotor zur Durchführung eines erfindungsgemäßen Verfahren zur Abgasnachbehandlung;
• 3 ein Ablaufdiagramm eines erfindungsgemäßen Verfahrens zum Betreiben eines Verbrennungsmotors, bei welchem die Leistung eines Nebenaggregats des Verbrennungsmotors reduziert oder das Nebenaggregat vollständig von dem Verbrennungsmotor entkoppelt wird, wenn eine dynamische Lastanforderung an den Verbrennungsmotors steigt, um die dynamische Motorlast und somit die Rohemissionen zu reduzieren.

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. They show:

• 1 a preferred embodiment of a motor vehicle with an internal combustion engine for carrying out a method according to the invention for exhaust gas aftertreatment;
• 2 a further embodiment of a motor vehicle with an internal combustion engine for carrying out a method according to the invention for exhaust gas aftertreatment;
• 3 a flowchart of a method according to the invention for operating an internal combustion engine, in which the power of an auxiliary unit of the internal combustion engine is reduced or the auxiliary unit is completely decoupled from the internal combustion engine when a dynamic load requirement on the internal combustion engine increases in order to reduce the dynamic engine load and thus the raw emissions.

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

The exhaust system 20 comprises an exhaust duct 22, in which a turbine 34 of an exhaust gas turbocharger 24 and an electrically heatable catalyst 26 are arranged in the flow direction of an exhaust gas flow of the internal combustion engine 10 through the exhaust duct 22. A first catalyst 28, in particular an oxidation catalyst or a NOx storage catalyst, is arranged downstream of the electrically heatable catalyst 26 and can be heated by the electrically heatable catalyst 26. Downstream of the first catalyst 28 is 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 is a third catalyst 40, in particular another SCT catalyst.

A first temperature sensor 36 is arranged upstream of the electrically heatable catalytic converter 26, and a second temperature sensor 38 is arranged downstream of the first catalytic converter 28. Downstream of the first catalytic converter 28 and upstream of the second catalytic converter 30, a metering element 42 is provided for metering a reducing agent into the exhaust passage 42. An exhaust mixer 44 is arranged downstream of the metering element 42 for better even distribution of the reducing agent throughout the exhaust gas flow. Downstream of the second catalytic converter 30 and upstream of the third catalytic converter 40, a second metering element 46 is arranged downstream of the metering element 46, which is arranged downstream of a second exhaust mixer 48. In a simplified embodiment of the exhaust system 20, the electrically heatable catalytic converter 26 can also be omitted.

The internal combustion engine 10 is coupled to a transmission 50, via which the wheels 68 of a drive axle 66 of the motor vehicle 1 are driven. The internal combustion engine 10 is further connected to a generator 52, which converts the kinetic energy of the internal combustion engine 10 into electrical energy. The generator 52 is preferably designed as a belt 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 of the motor vehicle 1, in particular a control unit for controlling the internal combustion engine 10 or the electrically heatable catalytic converter 26. The control unit 70 can be connected to the electrically heatable catalytic converter 26 via a second electrical line 60. 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. The internal combustion engine 10 is connected, preferably via a further drive belt, to an air conditioning compressor, which, as an auxiliary unit, is also driven by a crankshaft of the internal combustion engine 10 or a drive shaft connected to the crankshaft.

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

In the exhaust system 20, downstream of a turbine 34 of an exhaust gas turbocharger 24, an electrically heatable catalytic converter 26 is arranged, which is followed by a first catalytic converter 28, in particular a three-way catalytic converter or a four-way catalytic converter. Downstream of the first catalytic converter 28, a second catalytic converter 30 is provided, which is preferably designed as a three-way catalytic converter or a four-way catalytic converter. Downstream of the turbine 34 and upstream of the electrically heatable catalytic converter 26, a first temperature sensor 36 is arranged on the exhaust duct 22. Downstream of the first catalytic converter 28 and upstream of the second catalytic converter 30, a second temperature sensor is arranged on the exhaust duct 22. The temperature sensors are each connected to the control unit 70 via signal lines. In a simplified embodiment of the exhaust aftertreatment system, the electrically heatable catalyst 26 can also be omitted.

A known approach from the prior art aims at reducing the power of the auxiliary units in order to increase the peak power of the combustion engine. However, the prior art does not disclose that the power of the auxiliary units is reduced during a dynamic load demand in order to keep the necessary additional power of the combustion engine as low as possible and to avoid an increase in the engine's raw emissions. An example power curve during a dynamic load demand is shown in 3 shown in the Pt diagram in curve 1. Curve 2 represents this power curve including the load point shift of the auxiliary unit.

The present patent application is based on the idea of reducing the additional power of the internal combustion engine 10 when a dynamic demand is placed on the internal combustion engine 10. Reducing the load can, in particular, also mean completely shutting down the auxiliary units 52, 56, 72. The target power of the internal combustion engine 10 required by the dynamic demand is achieved by reducing or shutting down the auxiliary units, since the power provided by the internal combustion engine 10 for this purpose can be used directly to propel the motor vehicle 1. The difference between the target power and the actual power of the internal combustion engine 10, reduced by the generator power of the generator 52, 56 or the power of the air conditioning compressor 72, leads to reduced raw emissions from the internal combustion engine, since the intake path, in particular, reacts more stably to small changes.

Furthermore, the temperature inertia of the exhaust aftertreatment components 28, 30, 32, 40 leads to a delayed cooling of the exhaust aftertreatment components 28, 30, 32, 40. In relation to a driving cycle, it can be defined that during acceleration phases or when driving uphill, the power of the auxiliary units is reduced and is available without restriction during operating phases of the combustion engine 10 during constant speed or overrun. Such a course is shown in 3 represented by curve V1.

If a battery 64 with sufficient capacity is available, switching off the auxiliary units and the electrical auxiliary consumers can be avoided, with the energy for the electrical auxiliary consumers being made available directly by the battery 64 in order to relieve the load on the internal combustion engine 10.

In a first variant V1 of the method, it is provided that the reduction in the power of the auxiliary units 52, 56, 72 for the duration of the increased load demand on the internal combustion engine 10 occurs due to driving requirements such as an acceleration a of at least 1 m/s ² or a product of speed v and acceleration a of at least v * a ≥ 3 m ² / s ³ . Furthermore, the method can be triggered by driving up an incline with an average gradient of at least 5%.

In a second variant V2 of the method, the power of the auxiliary units 52, 56, 72 is reduced for the duration of the control deviation ΔAGR of the exhaust gas recirculation rate, with the power then gradually increasing to its initial value. The power increase of the auxiliary units 52, 56, 72 is initiated when the control deviation ΔAGR is less than 40%, preferably less than 20%, particularly preferably less than 10%. The maximum gradient of the power increase of the auxiliary units 52, 56, 72 or of electrical auxiliary consumers is 800 W/s, preferably 500 W/s, particularly preferably 300 W/s, in order to avoid any negative secondary effects due to the power adjustment.

The advantage of these variants is that by deactivating the auxiliary units 52, 56, 72, the power of the internal combustion engine 10 previously required for the auxiliary units 52, 56, 72 is immediately available for propelling the motor vehicle 1. As a result, the jump to the target power for the internal combustion engine 10 is smaller during a dynamic load demand, which reduces the raw emissions during this dynamic operation.

In general, with both variants V1 and V2, the reduction in the power of the combustion engine 10 and the associated reduction in the power of the generator 52, 56 can be compensated via a current from the battery 64 if sufficient energy is available in the battery 64.

List of reference symbols

1

Motor vehicle

10

combustion engine

12

combustion chamber

14

fuel injector

16

spark plug

18

Outlet

20

exhaust system

22

exhaust duct

24

exhaust gas turbocharger

26

electrically heated catalyst

28

first catalyst

30

second catalyst

32

Particle filter

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 mixer

50

Gearbox

52

generator

54

belt

56

Belt starter generator

58

first electrical line

60

second electrical line

62

third electrical line

64

battery

66

drive axle

68

wheel

70

control unit

72

air conditioning compressor

a

acceleration

m

meter

s

second

t

Time

v

speed

DS

Threshold value for a dynamic load requirement on the combustion engine

KW

kilowatt

P

Performance

T

temperature

TEG

Exhaust gas temperature

I

inventive method

II

State-of-the-art procedures

V1

first variant of the method according to the invention

V2

second variant of the method according to the invention

Claims (9)

Method for operating an internal combustion engine (10) having at least one combustion chamber (12), wherein the internal combustion engine (10) is connected by its outlet (18) to an exhaust system (20), and the internal combustion engine (10) is connected to at least one auxiliary unit (52, 56, 72), wherein the power of the auxiliary unit (52, 56, 72) is reduced in the event of a dynamic load request to the internal combustion engine (10) in order to reduce the overall additional engine load for the internal combustion engine (10) and thus to reduce the raw emissions of the internal combustion engine (10), characterized in that the power of all auxiliary units (52, 56, 72) is reduced or all auxiliary units (52, 56, 72) are switched off. Procedure according to Claim 1 , characterized in that the auxiliary unit (52, 56, 72) is switched off or mechanically decoupled from the internal combustion engine (10) when the dynamic requirement exceeds a threshold value (D _S ). Method according to one of the Claims 1 or 2 , characterized in that the dynamic load requirement is an acceleration (a) of the motor vehicle (1) of at least 1 m/s ² or a combination of speed (v) and acceleration (a) exceeds a limit value for which the following applies: v * a ≥ 3 m ² /s ³ . Method according to one of the Claims 1 or 2 , characterized in that the dynamic load requirement results from an ascending road with an average gradient of at least 5%. Method according to one of the Claims 1 until 4 , characterized in that the power of the auxiliary units (52, 56, 72) is increased again when a control deviation of the exhaust gas recirculation rate of the internal combustion engine (10) is less than 40%. Procedure according to Claim 5 , wherein the increase in the power of the electrical auxiliary units (52, 56, 72) occurs with a maximum gradient of 800 W/s. 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), and the internal combustion engine (10) is connected with at least one auxiliary unit (52, 56, 72), and with a control unit (70) which is designed to carry out a method according to one of the Claims 1 until 6 to be carried out when a machine-readable program code is executed by the control unit (70). Internal combustion engine (10) after Claim 7 , characterized in that the auxiliary unit (52, 56, 72) is a generator (52, 56), in particular a starter belt generator (56), or an air conditioning compressor (72). Internal combustion engine (10) after Claim 7 or 8 , characterized in that the internal combustion engine (10) can be connected to the auxiliary unit (52, 56, 72) via a separable clutch, wherein the separable clutch is opened when a dynamic load is required on the internal combustion engine (10) in order to reduce the required additional power.