Method for operating a powertrain in a motor vehicle and motor vehicle

Abstract

Method for operating a powertrain (10) in a motor vehicle (100), wherein the powertrain (10) comprises an internal combustion engine (20) with an exhaust aftertreatment system (30) associated with the internal combustion engine (20) and a transmission (50) for transmitting a drive torque generated by the internal combustion engine (20) to at least one drive axle (12, 14) of the motor vehicle (100), comprising the following steps: - Starting the internal combustion engine (20), wherein a torque-transmitting connection between the internal combustion engine (20) and the drive axle (12, 14) is interrupted or is interrupted, - Heating at least one exhaust aftertreatment component (32, 34, 36, 38) of the exhaust aftertreatment system (30) by an exhaust gas flow (70) of the internal combustion engine (20) while the torque-transmitting connection is interrupted until at least one release condition is reached, - Closing the torque-transmitting connection between the internal combustion engine (20) and the drive axle (12, 14) when the release condition is reached, so that a drive torque from the internal combustion engine (20) is transmitted to the drive axle (12, 14), wherein - the release condition includes two different conditions, namely - a defined time interval, which begins from the start of the internal combustion engine (20), and - a determination of heat input into the exhaust aftertreatment system (30) includes, wherein the release takes place after reaching the defined time interval and a defined amount of heat in the exhaust aftertreatment system (30), and wherein - from the start of the combustion engine (20) until the release is achieved, additional internal engine heating measures are carried out to shorten the time until the release condition is reached.

Description

[0001] The invention relates to a method for operating a drive train in a motor vehicle and to a motor vehicle with a control unit for carrying out such a method according to the preamble of the independent patent claims.

[0002] In view of the further tightening of emissions standards, for example with the introduction of the EU7 standard, it is necessary to significantly reduce cold-start emissions, which account for a large proportion of total emissions. During cold-start operation, i.e. immediately after starting the combustion engine, the exhaust aftertreatment components are generally not sufficiently warmed up to enable conversion of the raw emissions produced during fuel combustion. This leads, in particular, to increased exhaust emissions during the cold-start phase, which, even with complete conversion of the raw emissions after the cold-start phase, means that the limit values ​​are no longer met. The level of cold-start emissions is significantly influenced by the engine load during the cold-start phase.In particular, high engine loads during the cold start phase lead to high raw emissions from the combustion engine and thus to a significant increase in cold-start emissions, which are released unconverted into the environment. To avoid this, customer restrictions such as a reduction in power immediately after the combustion engine starts up may be necessary for state-of-the-art combustion engines with exhaust aftertreatment systems to ensure compliance with the EU7 emission limits under all required conditions.

[0003] To meet the EU6 emissions standard for gasoline engines, exhaust aftertreatment systems comprising one or more three-way catalysts and a particulate filter have become widespread. A three-way catalyst is a vehicle catalyst for the exhaust aftertreatment of internal combustion engines. It converts carbon monoxide (CO), nitrogen oxides (NOx), and unburned hydrocarbons (HC) into carbon dioxide (CO2), molecular nitrogen (N2), and water vapor (H2O). The name of the catalyst derives from the simultaneous conversion of these three air pollutants.

[0004] Furthermore, to ensure compliance with the emissions standard, close monitoring of the corresponding control or regulation of the combustion engine and the exhaust gas aftertreatment system is necessary.

[0005] US 2015 / 0 032 356 A1 discloses a method for heating a catalytic converter in the exhaust system of a motor vehicle. The engine speed is maintained at a high speed when the engine is started. This high speed is also maintained when the driver shifts the transmission out of neutral at a time I. The engine speed is reduced when, at a time II, an indication is detected that the driver intends to drive off, for example, when the driver releases the brake pedal.

[0006] US 2005 / 0 187 069 A1 describes a method for operating an internal combustion engine. An engine idle speed control device sets a target idle speed for a non-driving range to a high value in order to activate the catalytic converter early after the engine has been started. When it is detected that the automatic transmission has been shifted from a non-driving range to a driving range, the target idle speed is lowered to a first driving idle speed for a prescribed period of time. After the prescribed period of time has elapsed, the target idle speed is further lowered to a second target idle speed while driving. When the target idle speed is set to the first driving target idle speed, the amount of ignition timing retardation is adjusted depending on the actual engine speed such that the higher the engine speed, the more the ignition timing is retarded.

[0007] DE 10 2009 027 642 A1 discloses a method for operating a hybrid vehicle having a drive system with at least two different drive units, wherein at least one electric motor and at least one internal combustion engine having a catalytic converter are provided as drive units. During an initial start with a cold internal combustion engine, the hybrid vehicle is started at least electrically, with the internal combustion engine being started before, during, or after starting and operated in a combustion mode separate from the electric operation of the electric motor to heat the catalytic converter.

[0008] DE 10 2006 022 384 A1 describes a method for heating or keeping warm an exhaust gas purification device of a vehicle with a drive train comprising a transmission, which is driven by an internal combustion engine and at least one second drive unit. It is proposed that, even in an operating state that is outside of idle, a speed or torque of the internal combustion engine be set differently from the speed or torque values ​​that would be present in the same driving condition without heating or keeping warm the exhaust gas purification device.

[0009] The document DE 102011 085 260 A1 discloses a method for heating an exhaust catalyst of a hybrid vehicle. The hybrid vehicle comprises an internal combustion engine as the first drive motor, an electric motor as the second drive motor, and a clutch arranged downstream of the internal combustion engine. According to the method, during a cold start of the vehicle, the vehicle is driven by operating the electric motor without the internal combustion engine initially being operated. The vehicle thus starts up purely electrically without operating the internal combustion engine. Only later is the internal combustion engine started to heat the exhaust catalyst. During this catalyst heating operation, the clutch is open, so that the internal combustion engine does not drive the vehicle.

[0010] DE 10 2019 113 745 A1 discloses a method for operating a hybrid vehicle. An internal combustion engine of the hybrid vehicle comprises an internal combustion engine forming a combustion chamber and an exhaust system integrating an exhaust aftertreatment device, wherein the discharge of exhaust gas from the combustion chamber is controllable by means of an exhaust valve. The exhaust valve is actuated by means of a valve actuating device designed to vary the valve opening of the exhaust valve during the exhaust stroke during operation of the internal combustion engine. Starting up the motor vehicle triggers a start-up operation of the motor vehicle, during which the internal combustion engine of the internal combustion engine is preferably also immediately started.The combustion engine is operated in a heating mode in which, in order to achieve a relatively high temperature of the exhaust gas emitted from the combustion chamber, the valve opening of the exhaust valve during an exhaust stroke of the combustion engine is set smaller than in normal operation.

[0011] DE 10 2021 109 520 A1 describes a method for operating an internal combustion engine of a drive train of a vehicle during start-up, as well as a vehicle. The vehicle has an exhaust aftertreatment system for purifying exhaust gases from the internal combustion engine. After starting the internal combustion engine, the drive train is operated in a first operating state. In this first operating state, the internal combustion engine is idling, the exhaust aftertreatment system is heated by the internal combustion engine, and a start-up lock is active.The start-up lock active in the first operating state prevents starting using the internal combustion engine, wherein after reaching a predefined state of the exhaust gas aftertreatment system, the drive train is operated in a second operating state, wherein in the second operating state the start-up lock is inactive, so that in the second operating state starting using the internal combustion engine is possible.

[0012] Furthermore, DE 10 2014 200 077 A1 discloses a method for operating a hybrid drive system for an electric hybrid vehicle, wherein the hybrid drive system has an internal combustion engine and one or more electric motors for driving the electric hybrid vehicle. In drive mode, the electric motors deliver power to drive the electric hybrid vehicle and, in generator mode, can absorb power to provide electrical energy, which is stored in an accumulator. To shorten the warm-up phase of an exhaust gas aftertreatment unit, the internal combustion engine is controlled during the warm-up phase of the exhaust gas aftertreatment unit such that the internal combustion engine delivers more power than the hybrid drive system demands, with the additional power delivered above the demanded power being absorbed by the electric motor.The provision of the additional power is also dependent on the respective operating state of the combustion engine and is selectively controlled in such a way that the provision of the additional power is carried out or increased in engine operating states in which the additional power can achieve a particularly significant shortening of the warm-up phase.

[0013] The invention is based on the object of further reducing the cold start emissions in an internal combustion engine and of reaching an operating range of the exhaust gas aftertreatment system as quickly as possible in which an effective conversion of the limited pollutant emissions in the exhaust gas stream of the internal combustion engine is possible.

[0014] The object is achieved by a method for operating a drive train in a motor vehicle. The drive train comprises an internal combustion engine with an exhaust aftertreatment system associated with the internal combustion engine, as well as a transmission for transmitting a drive torque generated by the internal combustion engine to at least one drive axle of the motor vehicle. The method comprises the following steps: - Starting the internal combustion engine, whereby a torque-transmitting connection between the internal combustion engine and the drive axle is interrupted or will be interrupted, - heating at least one exhaust aftertreatment component of the exhaust aftertreatment system by an exhaust gas flow of the internal combustion engine, while the torque-transmitting connection is interrupted, until at least one release condition is reached, - Closing the torque-transmitting connection between the combustion engine and the drive axle when the release condition is reached, so that a drive torque of the combustion engine is transmitted to the drive axle.

[0015] The idling time allows at least one exhaust gas aftertreatment component to be heated up until a release condition is met, thus significantly reducing engine-out emissions at the start of a journey, as the actual start of the vehicle already takes place with the exhaust gas aftertreatment system preheated. Furthermore, interrupting the torque-transmitting connection prevents the idling time from being skipped, as during this time no desired torque is accepted by the driver via the accelerator pedal or, in automatic transmissions, engagement of a gear is blocked. This minimizes distance-related tailpipe emissions. Furthermore, the costs of the exhaust gas aftertreatment system can be minimized, as additional external heating means such as an electric heating element or a burner in the exhaust system can be dispensed with.

[0016] The features listed in the dependent claims enable advantageous embodiments and improvements as well as further developments of the method for operating a drive train of a motor vehicle mentioned in the independent claim.

[0017] According to the invention, the release condition is a defined time interval beginning with the start of the combustion engine. During this predefined time interval, the exhaust aftertreatment system can be heated up, and the driver is shown, for example, via the instrument cluster, a precise time period that they must wait until release. The defined time interval is preferably in the range of 5 seconds to 20 seconds, preferably in the range of 10 seconds to 15 seconds, thereby achieving a significant heat-up of the exhaust aftertreatment component.

[0018] In a preferred embodiment of the method, the transmission is designed as an automatic transmission and the torque-transmitting connection between the internal combustion engine and the drive axle is or will be interrupted by preventing the automatic transmission from engaging a gear until the release condition is met. In this context, an automatic transmission is understood to mean, in particular, an automatic transmission in the form of a dual-clutch transmission or a torque converter automatic transmission. Preventing the engagement of a gear in this context means, in particular, holding the transmission in a "P" or "N" position and electronically or electromechanically preventing the transmission from engaging a "D" or "R" position.This provides a simple and reliable way to prevent the engine's drive torque from being transferred to a vehicle's drive axle, thereby increasing the engine's load. This allows for optimal emissions during the warm-up phase.

[0019] In a further preferred embodiment of the method, the transmission is designed as an automated manual transmission in which the clutch is controlled electronically or electromechanically. In this case, gear engagement is also inhibited until the release condition is met. This provides a simple and reliable way to prevent drive torque from the internal combustion engine from being transferred to a drive axle of the motor vehicle, thus increasing the load on the internal combustion engine. This allows for emission-optimized operating conditions to be achieved during the warm-up phase.

[0020] In a further preferred embodiment of the method, the release condition includes determining the temperature of at least one exhaust gas aftertreatment component, with the release occurring after reaching a defined minimum temperature for the exhaust gas aftertreatment component. Thus, the drive is only released when the exhaust gas aftertreatment system reaches a certain operating temperature and thus has a certain level of efficiency. This ensures that the exhaust gas aftertreatment system demonstrates a minimum level of efficiency at the start of the journey, thus reducing tailpipe emissions.

[0021] According to the invention, the release condition includes determining the heat input into the exhaust aftertreatment system, with the release occurring after reaching a defined heat quantity in the exhaust aftertreatment system. This offers a further possibility for controlling the departure deceleration, whereby reaching the predefined heat quantity ensures a minimum effectiveness of the exhaust aftertreatment, thus reducing emissions at the start of the journey.

[0022] In a further preferred embodiment of the method, the release condition includes determining a conversion efficiency of at least one exhaust gas aftertreatment component, with release occurring when the conversion efficiency of the exhaust gas aftertreatment component has reached a defined threshold. Determining the conversion efficiency provides the most direct control of the effectiveness of the exhaust gas aftertreatment and can thus ensure that the start of the journey is delayed until the exhaust gas aftertreatment reduces the tailpipe emissions to a prescribed level.

[0023] According to the invention, the release condition comprises at least two conditions from the following group: - a defined time interval from the start of the combustion engine, - a defined minimum temperature for the exhaust aftertreatment component, - a defined amount of heat introduced into the exhaust aftertreatment system, - a defined threshold value of the conversion performance of the exhaust gas aftertreatment component.

[0024] The combination of different release conditions offers the advantage of greater performance reliability of the exhaust aftertreatment system and the associated reduction in emissions.

[0025] According to the invention, additional internal engine heating measures are implemented from the start of the combustion engine until the release condition is reached, in order to shorten the time until the release condition is reached. For example, by delaying the ignition timing or by operating the secondary air pump, the exhaust gas temperature can be increased, thus heating the exhaust gas aftertreatment components. This allows the exhaust gas aftertreatment components to reach their operating temperature more quickly and shortens the time until the vehicle is released.

[0026] In a further preferred embodiment of the method, additional off-engine heating measures are implemented until the release condition is met in order to shorten the time until the release condition is met. Electrically heated catalysts or burner systems can additionally heat the exhaust aftertreatment systems off-engine, thereby reaching the operating temperature of the exhaust aftertreatment system more quickly and thus reducing idle time.

[0027] A further aspect of the invention relates to a control unit for a motor vehicle, comprising a memory unit and a computing unit as well as a computer program code stored in the memory unit, wherein the control unit is configured to carry out a method described in the preceding sections when the computer program code is executed by the computing unit.

[0028] A further aspect of the invention relates to a motor vehicle with such a control unit.

[0029] The various embodiments of the invention mentioned in this application can be advantageously combined with one another, unless otherwise stated in the individual case.

[0030] The invention is explained below in exemplary embodiments with reference to the accompanying drawings. They show: Fig. 1 preferred embodiment of a motor vehicle with a drive train for carrying out a method according to the invention, Fig. 2 shows a further preferred embodiment of a motor vehicle with a drive train for carrying out a method according to the invention for operating the drive train, and Fig. 3 a flow chart for carrying out a method according to the invention for operating a drive train in a motor vehicle.

[0031] Fig. 1 shows a preferred embodiment of a motor vehicle 100 with a drive train 10 for carrying out a method according to the invention. The drive train 10 has at least one drive axle 12, 14 with a differential 16, wherein the drive axles 12, 14 are connected to the wheels 18 of the motor vehicle. The first drive axle 12 is connected to the transmission 50, in particular an automated manual transmission 54, which is connected to an internal combustion engine 20 via a clutch 52. For this purpose, a shift element 56 for automatically actuating the clutch 52 is arranged on the clutch 52. Alternatively, the transmission 50 can also be designed as an automatic transmission 58. The internal combustion engine 20 has a plurality of combustion chambers 22. A fuel injector 24 for injecting a fuel into the respective combustion chamber 22 is arranged at each of the combustion chambers 22.Furthermore, a spark plug 26 is arranged on each combustion chamber 22 for igniting an ignitable fuel-air mixture in the respective combustion chamber 22. The combustion chamber 22 is heated by a spark plug 26. Fig. 1, which is slidably arranged in a cylinder of the internal combustion engine 20. The piston is connected via a connecting rod to a crankshaft of the internal combustion engine 20, wherein the connecting rod transmits an oscillating movement of the piston into a rotary movement of the crankshaft. The internal combustion engine 20 is connected with its inlet to a Fig. 1, and connected to an exhaust system 40 via its outlet 28. Inlet valves and outlet valves are arranged on the combustion chambers 22, with which a fluidic connection from the air supply system to the combustion chambers 22 or from the combustion chambers 22 to the exhaust system 40 can be opened or closed.

[0032] The exhaust system 40 comprises an exhaust duct 42 with an exhaust gas aftertreatment system 30, in which a turbine 46 of an exhaust gas turbocharger 48 is located in the flow direction of an exhaust gas flow 70 of the internal combustion engine 20 through the exhaust system 40, a first catalyst 32, in particular a three-way catalyst 38, downstream of the turbine 46 of the exhaust gas turbocharger 48, a particulate filter 34 downstream of the first catalyst 32, and a second catalyst 36, in particular a second three-way catalyst 38, downstream of the particulate filter 34.

[0033] Downstream of the turbine 46 of the exhaust gas turbocharger 48 and upstream of the first catalyst 32, a first temperature sensor 44 is arranged for measuring the temperature of the exhaust gas flow 70 in the exhaust system 40. Downstream of the particulate filter 34 and upstream of the second catalyst 36, a second temperature sensor 44 is provided for measuring the temperature of the exhaust gas flow 70 in the exhaust system 40.

[0034] The drive train 10 is assigned a control unit 60 with a memory unit 62 and a computing unit 64. A computer program code 66 is stored in the memory unit 62, which, when the computer program code 66 is executed by the computing unit 64, executes a method according to the invention for operating a drive train of a motor vehicle 100. Furthermore, data is transmitted to an on-board monitoring unit 68 integrated in the control unit 60.

[0035] In addition, a combination instrument 102 with a display element 104 is provided for the motor vehicle 100.

[0036] In Fig. 2 shows an alternative embodiment of a motor vehicle 100 with a drive train 10, in particular with a hybrid drive 80 for carrying out a method according to the invention. The drive train 10 has two drive axles 12, 14, each with a differential 16, wherein the drive axles 12, 14 are connected to the wheels 18 of the motor vehicle 100. The drive train 10 further comprises an internal combustion engine 20, an electric drive motor 82 and a transmission 50, in particular an automatic transmission 58. The internal combustion engine 20 has a plurality of combustion chambers 22. A fuel injector 24 for injecting a fuel into the respective combustion chamber 22 is arranged at each of the combustion chambers 22. Furthermore, a spark plug 26 for igniting an ignitable fuel-air mixture in the respective combustion chamber 22 is arranged at each combustion chamber 22. The combustion chamber 22 is heated by a Fig. 2, which is slidably arranged in a cylinder of the internal combustion engine 20. The piston is connected to a crankshaft of the internal combustion engine 20 via a connecting rod, wherein the connecting rod transmits an oscillating movement of the piston into a rotary movement of the crankshaft.

[0037] In the Fig. 2, a clutch 52 is arranged between the internal combustion engine 10 and an electric drive motor 82 that can be connected to the transmission 50. The transmission 50 is preferably designed as an automatic transmission 58. The internal combustion engine 20 is connected with its inlet to a Fig. 2, and connected to an exhaust system 40 via its outlet 28. Inlet valves and outlet valves are arranged on the combustion chambers 22, with which a fluidic connection from the air supply system to the combustion chambers 22 or from the combustion chambers 22 to the exhaust system 40 can be opened or closed.

[0038] The exhaust system 40 comprises an exhaust duct 42 with an exhaust aftertreatment system 30, in which a turbine 46 of an exhaust gas turbocharger 48 is located in the flow direction of an exhaust gas flow 70 of the internal combustion engine 20 through the exhaust system 40, a first catalyst 32, in particular a three-way catalyst, downstream of the turbine 46 of the exhaust gas turbocharger 48, and a second catalyst 36, in particular a four-way catalyst 39, downstream of the first catalyst 32. A temperature sensor 44 for measuring the temperature of the exhaust gas flow 70 in the exhaust system 40 is arranged downstream of the turbine 46 of the exhaust gas turbocharger 48 and upstream of the first catalyst 32.

[0039] The drive train 10 is assigned a control unit 60 with a memory unit 62 and a computing unit 64. A computer program code 66 is stored in the memory unit 62, which, when the computer program code 66 is executed by the computing unit 64, executes a method according to the invention for operating a drive train of a motor vehicle 100. Furthermore, data is transmitted to an on-board monitoring unit 68 integrated in the control unit 60.

[0040] In addition, a combination instrument 102 with a display element 104 is provided for the motor vehicle 100.

[0041] In Fig.3 shows a flowchart for carrying out a method according to the invention for operating a drive train in a motor vehicle. In a first method step <100> The internal combustion engine 20 is started, whereby a torque-transmitting connection between the internal combustion engine 20 and the drive axle 12, 14 is interrupted or will be interrupted. This can occur, for example, by disengaging the clutch 52 in a manual transmission 54 or by engaging the "N" position in an automatic transmission 58.

[0042] In one process step <105> An estimated idle time until release can be calculated and displayed to the driver, in particular by a symbol or text in the instrument cluster 102. In one process step <110> At least one exhaust aftertreatment component 32, 34, 36, 38 of the exhaust aftertreatment system 30 is heated by an exhaust gas flow 70 of the internal combustion engine 20, while the torque-transmitting connection is interrupted, until at least one release condition is met. The release condition can be a defined time interval, the reaching of a minimum temperature of an exhaust aftertreatment component, or the determination of a heat input, with the release occurring after a defined amount of heat has been reached in the exhaust aftertreatment system 30.Alternatively or additionally, the release condition may comprise the determination of a conversion performance of at least one exhaust gas aftertreatment component 32, 34, 36, 38, wherein release occurs when the conversion performance of the exhaust gas aftertreatment component 32, 34, 36, 38 has reached a defined threshold value. Furthermore, it may be provided that the release comprises a combination of different release conditions, with prioritization of the simultaneously evaluated release conditions taking place.

[0043] In one process step <115> The exhaust aftertreatment components 32, 34, 36, 38 can also be heated externally by an electric heating element or a burner system to shorten the time until release. Alternatively or additionally, the exhaust aftertreatment components 32, 34, 36, 38 can also be heated by internal engine heating measures, for example, by adjusting the ignition timing toward "retard."

[0044] In one process step <120> the torque-transmitting connection between the internal combustion engine 20 and the drive axle 12, 14 is closed when the release condition is reached, so that a drive torque of the internal combustion engine 20 is transmitted to the drive axle 12, 14. List of reference symbols 10 Drivetrain 12 first drive axle 14 second drive axle 16 Differential 18 wheel 20 combustion engine 22 combustion chamber 24 Fuel injector 26 Spark plug 28 Outlet 30 Exhaust aftertreatment system 32 first catalyst 34 particle filters 36 second catalyst 38 Three-way catalyst 39 Four-way catalyst 40 Exhaust system 42 exhaust duct 44 Temperature sensor 46 turbines 48 exhaust gas turbochargers 50 gearboxes 52 Clutch 54 manual transmissions 56 switching element 58 automatic transmissions 60 control unit 62 storage unit 64 computing unit 66 Computer program code 68 On-board monitoring unit 70 exhaust gas flow 80 hybrid drive 82 electric drive motor 100 motor vehicles 102 instrument cluster 104 Display element

Claims

[1] Method for operating a drive train (10) in a motor vehicle (100), wherein the drive train (10) has an internal combustion engine (20) with an exhaust gas aftertreatment system (30) assigned to the internal combustion engine (20) and a transmission (50) for transmitting a drive torque generated by the internal combustion engine (20) to at least one drive axle (12, 14) of the motor vehicle (100), comprising the following steps: - starting the internal combustion engine (20), wherein a torque-transmitting connection between the internal combustion engine (20) and the drive axle (12, 14) is or will be interrupted, - heating at least one exhaust gas aftertreatment component (32, 34, 36, 38) of the exhaust gas aftertreatment system (30) by an exhaust gas flow (70) of the internal combustion engine (20), while the torque-transmitting connection is interrupted until at least one release condition is reached, - closing the torque-transmitting connection between the internal combustion engine (20) and the drive axle (12, 14) when the release condition is reached, so that a drive torque of the internal combustion engine (20) is transmitted to the drive axle (12, 14), wherein - the release condition comprises two different conditions, namely - a defined time interval starting from the start of the combustion engine (20), and - a determination of a heat input into the exhaust gas aftertreatment system (30), wherein the release takes place after reaching the defined time interval and a defined amount of heat in the exhaust gas aftertreatment system (30), and wherein - from the start of the combustion engine (20) until the release is reached, additional internal engine heating measures are carried out in order to shorten the period until the release condition is reached. [2] Method according to claim 1, wherein the release condition comprises determining a temperature of at least one exhaust gas aftertreatment component (32, 34, 36, 38), wherein the release occurs after reaching a defined minimum temperature for the exhaust gas aftertreatment component (32, 34, 36, 38). [3] Method according to one of claims 1 or 2, wherein the release condition comprises a determination of a conversion performance of at least one exhaust gas aftertreatment component (32, 34, 36, 38), wherein a release occurs when the conversion performance of the exhaust gas aftertreatment component (32, 34, 36, 38) has reached a defined threshold value. [4] Method according to one of claims 1 to 3, wherein additional extra-engine heating measures are carried out until the release condition is reached in order to shorten the period until the release condition is reached. [5] Control unit (60) for a motor vehicle (100), comprising a memory unit (62) and a computing unit (64) and a computer program code (66) stored in the memory unit (62), wherein the control unit (60) is configured to carry out a method according to one of claims 1 to 4 when the computer program code (66) is executed by the computing unit (64). [6] Motor vehicle (100) with a control device according to claim 5.

Images