DE102019200491A1 - Method for controlling a drive train of a vehicle - Google Patents

Abstract

The present disclosure relates to a method for controlling a drive train of a vehicle, which has an internal combustion engine with an electrically assisted engine charging system and a further drive motor in the form of an electrical machine. In the method, a target drive torque that is to be generated by the drive train is detected. Furthermore, a lambda setpoint is determined as a function of the setpoint drive torque and a fuel supply for reaching the setpoint drive torque is determined. Taking into account the target lambda value, a gas supply is set with the aid of the electrically assisted engine charging system, taking into account the determined fuel supply, an actual lambda value is determined. A lambda control deviation is corrected by adjusting the fuel supply. A torque change of the internal combustion engine resulting from the correction of the lambda control deviation is compensated for by the electrical machine in order to achieve the target drive torque. Furthermore, a control device and a vehicle with a control device are disclosed.

Description

The invention relates to a method for controlling a drive train of a vehicle, a control device for executing a method and a vehicle with a control device.

In dynamic phases of internal combustion engines, the different settling times / reaction speed of the fuel path and gas path lead to increased emissions, e.g. Nitrogen oxide and soot. The reason for this is the deviation between the applied target air mass and the actual air mass in the cylinder during the dynamic phase, whereas the target fuel quantity to be injected can essentially be implemented immediately by an injection device. This means that there is not enough air available for the amount of fuel injected, so that combustion is not optimal for emissions. In order to reduce the emissions arising in the dynamics, i.a. the following approaches are known.

In the DE 197 08 721 A1 soot formation when starting an internal combustion engine is suppressed by a second compressor driven by an electric motor supporting a first compressor of an exhaust gas turbocharger. A pilot charge is achieved by the electrically operated second compressor, which, in feedback with the internal combustion engine, enables rapid startup without any significant soot formation.

Nevertheless, there may be a delay in adjusting the air mass to be applied, since the electrically operated second compressor is also subject to inertia and because there is a volume and / or a distance (given, for example, by the charge air pipe / air path, charge air cooler section, intake pipe and inlet duct) between the second compressor and the internal combustion engine must be bridged or a corresponding (charging) pressure must first be built up within the volume and / or the route. The emissions resulting from this delay in the gas or air supply can be overcome by controlling the electric compressor at an early stage, for which the driver's request (acceleration request) and thus the increase in fuel quantity can be predicted or the driver's request would have to be implemented with a delay. However, the former cannot be implemented and the latter deteriorates the driving dynamics.

Another possibility is to adapt the amount of fuel to the actual air mass supplied to the combustion chamber. However, this leads to a delay in the torque build-up and therefore, from the customer's point of view, to an unacceptable deterioration in driving dynamics. The remedy here is the support of an electric drive.

Out DE 10 2008 041 566 A1 It is known to check whether an actual lambda value detected when a torque request changes lies within an interval of permitted ranges and that, if it lies outside, a fuel quantity supplied to an internal combustion engine is corrected so that the actual lambda value returns within the permitted range. A change in the torque contribution resulting from the correction is compensated for by a controlled change in a torque contribution of the second drive motor, which can be an electrical machine.

A high level of driving dynamics can be achieved with simultaneous adaptation of the fuel supply to the air supply. However, compensation of the change in torque contribution by the electric drive is possible only to a limited extent, depending on the available electrical power.

The object of the present invention is to provide a method, a control device and a vehicle which at least partially overcome the disadvantages mentioned above.

This object is achieved by a method according to claim 1, a control device according to claim 9 and a vehicle according to claim 10. Further advantageous refinements of the invention result from the subclaims and the following description of preferred exemplary embodiments of the present invention.

• Erfassen eines von dem Antriebsstrang zu erzeugenden Soll-Antriebsmoments;
• Bestimmen eines Lambda-Sollwerts in Abhängigkeit des Soll-Antriebsmoments;
• Ermitteln einer Kraftstoffzufuhr zum Erreichen des Solls-Antriebsmoments;
• Einstellen einer Gaszufuhr mit Hilfe des elektrisch unterstützten Motoraufladungssystems unter Beachtung des Lambda-Sollwerts;
• Ermitteln eines Lambda-Istwerts unter Berücksichtigung der ermittelten Kraftstoffzufuhr;
• Korrigieren einer Lambda-Regelabweichung durch Anpassen der Kraftstoffzufuhr; und Kompensieren, insbesondere zumindest teilweise, einer aus der Korrektur der Lambda-Regelabweichung resultierenden Drehmomentänderung des Verbrennungsmotors durch die elektrische Maschine zum Erreichen des Soll-Antriebsmoments.

A first aspect of the present disclosure relates to a method for controlling a drive train of a vehicle, which has an internal combustion engine with an electrically assisted engine charging system and a further drive engine in the form of an electrical machine, with:

• Detecting a target drive torque to be generated by the drive train;
• Determining a lambda setpoint as a function of the setpoint drive torque;
• Determining a fuel supply to achieve the target drive torque;
• Adjusting a gas supply with the aid of the electrically assisted engine charging system taking into account the lambda setpoint;
• Determining an actual lambda value taking into account the determined fuel supply;
• Correcting a lambda control deviation by adjusting the fuel supply; and compensating, in particular at least partially, one from the correction of the lambda Control deviation resulting torque change of the internal combustion engine by the electrical machine to achieve the target drive torque.

The target drive torque reflects a vehicle speed or acceleration desired by a driver. This driver request is detected, for example, by evaluating an accelerator pedal position and / or a change in the accelerator pedal value of the vehicle, e.g. using sensors. In particular, an acceleration request from the driver is recorded, that is to say a target drive torque increase.

A lambda setpoint is determined depending on the setpoint drive torque. The lambda value indicates a combustion air ratio used in the internal combustion engine. In particular, the desired lambda value can be determined from a map for operating the internal combustion engine. The lambda value can thus be dependent on the power of the internal combustion engine. The internal combustion engine is preferably designed as a diesel engine, the output (torque generation) of which can be controlled or regulated by qualitative mixture regulation (or also quality regulation). In order to generate a torque, the mixture quantity supplied to a combustion chamber of the diesel engine remains essentially unchanged, but the lambda value, that is to say the quality of the mixture, is changed.

The necessary fuel supply is determined so that the internal combustion engine can provide the desired drive torque. A target fuel quantity of the fuel is therefore calculated / ascertained, which must be supplied to the internal combustion engine so that the internal combustion engine alone can generate the target drive torque.

An air mass supplied to the internal combustion engine can be set via the gas supply. Furthermore, a combustion exhaust gas can be fed to the combustion engine in an adjustable manner via the gas supply (via an exhaust gas recirculation line). A target air mass is determined on the basis of the lambda target value and the corresponding (determined) target fuel quantity of the fuel, so that combustion of a fuel-air mixture, in which the target values for fuel and air mass are adhered to, the lambda Adheres to the setpoint. In other words, if the target values for air mass and fuel are observed, the target lambda value is reached.

However, the gas supply (as described above) is subject to a delay and cannot provide the desired air mass immediately. An actual air mass is therefore, at least for a certain time, below the target air mass. As a result, there is not enough air available for the amount of fuel injected, so that the combustion is not optimal for emissions. This delay can be at least partially compensated for with the aid of the electrically assisted charging system. At least a certain emission reduction in dynamic operation of the internal combustion engine is possible by means of the electrically assisted engine charging system. For example, electrically assisted exhaust gas turbochargers or eBoosters can be used.

Accordingly, an actual lambda value can be determined taking into account the determined target fuel quantity and the actual air mass. A lambda control deviation can be determined from the actual and target values for lambda, i.e. a difference between these two values.

In order to correct this lambda control deviation, the fuel supply, in particular an actual fuel quantity, is adjusted. Since the actual air mass in dynamic phases of the internal combustion engine is below the target air mass at least for a certain period of time due to the delay in the gas supply, for example due to the inertia of the electrically assisted engine charging system, the actual fuel quantity is adapted to the actual air mass. In other words, the actual fuel quantity is also below the target fuel quantity. If the lambda control deviation is corrected, the actual fuel quantity falls below the target fuel quantity that has to be supplied to the internal combustion engine so that it could generate the target drive torque alone.

With the actual fuel quantity (and therefore with a combustion gas mixture with a lower lambda value), the internal combustion engine generates a lower torque than with the target fuel quantity. This torque difference (torque change) can be at least partially compensated for by operating the electrical machine. For this purpose, the electric machine generates a torque which acts in addition to the torque generated by the internal combustion engine. In the optimal case, the target drive torque is completely achieved by the sum of the torques from the electric drive and the internal combustion engine. As a result, driving dynamics to be achieved by the drive train can be at least partially maintained. The electrical machine can be designed, for example, as a belt / crankshaft starter generator or as an electrical drive machine (as in a plug-in hybrid vehicle).

Through the above method, the electrical drive and the electrical supported engine charging system, a combustion gas mixture provided for emission-optimized combustion is made available to the internal combustion engine in its dynamic phases as quickly as possible, while at the same time the driving dynamics can be implemented based on the driver's request.

In an alternative, the lambda control deviation can be corrected in such a way that the lambda control deviation is within an allowed interval. This interval can be set in such a way as to comply with certain upper emission limits, while at the same time high driving dynamics (through more fuel injection) is made possible.

In one variant, the electrically assisted engine charging system can have an exhaust gas turbocharger with a first compressor and an electrically driven second compressor. The electrical drive of the second compressor means that the torque generated by the internal combustion engine does not have to be used to operate the second compressor, as a result of which more engine power is available for driving the vehicle. Furthermore, due to its electrical drive, the second compressor is independent of an engine speed / power of the internal combustion engine and of an exhaust gas flow and can therefore be optionally switched on. By optionally switching on the second compressor, a turbo lag can be at least partially compensated for in the transient operation of the internal combustion engine. By decoupling the exhaust gas turbocharger and the power of the internal combustion engine, the second compressor can be arranged as desired along the air supply line / the air path of the internal combustion engine. This makes the second compressor particularly easy to integrate into a system concept.

In one embodiment, the second compressor can be arranged downstream of the first compressor. “Downstream” here means that the (fresh) air in a flow direction to the internal combustion engine first passes the first and then the second compressor. This downstream arrangement of the second compressor, in particular close to an intake side of the internal combustion engine, enables rapid boost pressure build-up and correspondingly good driving dynamics due to the shortened distance between the second compressor and the internal combustion engine.

The second compressor arranged downstream can enable a more precisely adjustable compression of the air mass supplied to the combustion chamber than a reverse arrangement of the first and second compressors. Thus, the air compressed by the second compressor arranged downstream is not impeded by an impeller of the first compressor, and the compression of the air mass is not influenced by the first compressor. Especially when the internal combustion engine is in stationary operation and a load request is made, the compressor of the exhaust gas turbocharger (due to its dependence on the exhaust gas flow to implement the load request) can only reach the required speed after a delay, while the second compressor can reach the required speed due to its electrical drive can deploy faster. Therefore, with the above-mentioned reverse arrangement of the compressors, the air mass compression would be less precise, since the first compressor would apply a lower compressor output than the second compressor, at least for a period of time.

In one variant, the second compressor is operated as long as it is switched on as long as the lambda control deviation is present (in particular during the transient operation of the internal combustion engine). This ensures that the air mass can be adjusted as quickly as possible with the support of the second compressor.

In one embodiment, a feed line of the second compressor can branch off from an air path of the internal combustion engine and a discharge line of the second compressor can open into the air path downstream of the feed line branch into the air path. For example, the supply line and the discharge line can be designed as a “suction” or a “pressure connection” of the second compressor. Thus, when the second compressor is not needed and therefore is not operated, the air pre-compressed by the first compressor can bypass the second compressor. It is thus at least partially prevented that a flow of this pre-compressed air runs through the second compressor and thereby experiences an unnecessary deflection.

Furthermore, the gas supply to the internal combustion engine from the first and the second compressor can be adjustable via an actuating arrangement. In this case, the actuating arrangement can comprise, for example, a 3-way control flap which is arranged in the air path in such a way that it is located downstream of the first compressor and the derivative of the second compressor opens into the 3-way control flap. The 3-way control flap can be designed in such a way that in a first position of the 3-way control flap the air supplied to the internal combustion engine (downstream of the first compressor) can be conducted completely via the second compressor, in a second position the 3-way control valve Control flap has a maximum flow cross-section for the air pre-compressed by the first compressor and an air supply to the internal combustion engine is prevented in a third position. Other actuating arrangements that have the same function are also possible such as a 3-way mixing valve. This variant of the actuating arrangement represents a comparatively lower or even no flow resistance for air pre-compressed from the second compressor, which is conducted to the internal combustion engine via this actuating arrangement.

Alternatively, the actuating arrangement can comprise a throttle valve and a check valve. The check valve can be designed, for example, as a check valve or flap, although other forms of check valves are also possible. Other devices are also possible which have a mechanism for preventing backflow. In this case, the throttle valve can be arranged between the branch of the feed line of the second compressor and the confluence of the discharge line of the second compressor in the air path. The check valve can be arranged between the junction and the second compressor. The throttle valve can be controllable / adjustable in such a way that it can meter the amount of air mass pre-compressed by the first compressor, which is supplied to the internal combustion engine. This passive variant of the actuating arrangement is structurally simple and requires less or no additional actuators.

Furthermore, the electrical machine can be coupled to an output shaft of a transmission (of the drive train), to a transmission shaft or to a crankshaft of the internal combustion engine. In other words, a torque generated by the electrical machine can be introduced at the points / components described above in order to contribute to the drive torque of the vehicle.

A second aspect of the present disclosure relates to a control device for an in particular electrified drive train of a vehicle. The control device is set up and designed to carry out the method according to the invention as well as the above-described configurations and alternatives.

A third aspect of the present disclosure relates to a vehicle with the control device described above, the drive train of which can be controlled in accordance with the method according to the invention and the embodiments and alternatives described above.

• 1 eine schematische Darstellung eines Antriebsstrangs;
• 2 eine Steuerung von Antriebsstrangkomponenten;
• 3a-c ein Diagramm mit Verläufen von Betriebsgrößen des Antriebsstrangs; und
• 4 einen Ablauf eines Steuerverfahrens für den Antriebsstrang.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings. It shows

• 1 a schematic representation of a drive train;
• 2nd control of powertrain components;
• 3a-c a diagram with profiles of operating variables of the drive train; and
• 4th a flow of a control procedure for the drive train.

In 1 is a powertrain 1 of a vehicle 100 shown. The drivetrain 1 has an internal combustion engine 2nd , another drive motor in the form of an electrical machine 4th , a clutch 18th and a gear 20 , in particular change gear. A control unit 30th is set up, in particular programmed to control the sequence of one of the methods presented in the present disclosure. This is what the control unit is for 30th further set up the components of the drive train required for the sequence 1 to control.

The internal combustion engine 2nd is supplied with fresh air via a fresh air system, which is an air duct 5 (Air path / gas path). Furthermore, an injector 7 the internal combustion engine 2nd Fuel supplied, the injector 7 is designed to (from the control unit 30th ) certain injection periods, injection quantities and injection times into the (not shown) cylinders of the internal combustion engine 2nd to enable.

Furthermore, the internal combustion engine 2nd an electrically assisted engine charging system that includes an exhaust gas turbocharger 6 with a first compressor 6a and a turbine 6b and an electrically driven second compressor 8th having. The first compressor 6a compresses the over the air line 5 the internal combustion engine 2nd supplied air. The second compressor 8th can the exhaust gas turbocharger 6 Support when building up the boost pressure when lifting a load. The second compressor 8th is downstream of the first compressor 6a arranged. A supply line to the second compressor 8th branches from the air duct 5 and a derivative of the second compressor 8th opens downstream of the branch of the feed line of the second compressor 8th back into the air line via a 3-way control flap 10 5 a. The 3-way control valve 10th is in the air line 5 downstream of the branch line of the second compressor 8th arranged. The 3-way control valve 10th can assume a first position, in the downstream of the first compressor 6a the (the internal combustion engine 2nd supplied) air is completely passed through the second compressor. In 1 this first position is shown by the dashed alignment of the 3-way control valve.
Furthermore, the 3-way control valve 10th assume a second position (not shown) in which the 3-way control flap 10th the largest possible flow cross-section for that of the first compressor 6a pre-compressed air through the 3-way control valve 10th flows / is flowable, provides. This second position corresponds to the 1 a (not shown) vertical alignment of the flap of the 3-way control flap 10th . In a third position, the 3-way control valve can 10th an air supply to the internal combustion engine 2nd prevent (completely). So neither is that from the first compressor 6a still from the second compressor 8a pre-compressed air to the internal combustion engine 2nd feedable. The third position is shown by the alignment of the 3-way control valve shown as a solid line. Via the 3-way control valve 10th can also the the internal combustion engine 2nd Air volume supplied can be adjusted by the 3-way control valve 10th occupies a position between the second and third position. In an alternative, the 3-way control valve 10th also take a position between the first and the second position for adjusting the amount of air. The 3-way control valve 10th can therefore perform a throttle function, such as with a classic throttle valve. It is also possible that the 3-way control valve 10th occupies other positions that are not described here.

In the operation of the internal combustion engine 2nd usually becomes the second compressor 8th operated while the 3-way control valve 10th is in the first position. In the second position without the second compressor operating 8th becomes the first compressor 6a Pre-compressed air follows the flow path with the least resistance and not via the second compressor 8th , but directly along the air duct 5 (and via the 3-way control valve 10th ) headed. In the third position, both compressors can 6a , 8th to be out of order.

Alternatively, instead of the 3-way control valve 10th another control arrangement is also possible, such as a 3-way mixing valve, as long as it has the functions of the 3-way control flap described above 10th can execute.

Furthermore, in 1 also an alternative actuator arrangement 10 ' shown (see circle). The alternative positioning arrangement 10 ' includes a throttle valve 10a and a check valve 10b . The throttle valve 10a is in the air line 5 between the branch and the junction of the second compressor 8th from or into the air line 5 arranged and is used to adjust the internal combustion engine 2nd amount of air supplied. The check valve 10b is between the junction and the second compressor 8th arranged. In other words, the check valve is in the discharge line of the second compressor 8th . The check valve 10b can, for example, be designed in such a way that it opens automatically, provided that the second compressor 8th a higher pressure than the first compressor 6a generated.

In the air line 5 is after the first and second compressor 6a , 8th a charge air cooler 22 arranged which the the internal combustion engine 2nd supplied compressed air can cool.

From the internal combustion engine 2nd Combustion exhaust gases are discharged via an exhaust gas discharge system, which is an exhaust pipe 15 having. An exhaust gas recirculation line also branches off 16 from the exhaust pipe 15 to exhaust gases into the fresh air system, e.g. into the air line 5 to initiate. The exhaust gas recirculation line opens 16 (downstream of the air line 5 seen from) after the intercooler 22 in the air line 5 . Alternatively, the exhaust gas recirculation line 16 can also be initiated at another sensible point in the fresh air system. A throttle 17th is in the exhaust gas recirculation line 16 arranged. Via the throttle valve 17th an exhaust gas quantity fed into the fresh air system can be controlled. Alternative metering devices, such as a valve, are instead of the throttle valve 17th possible.

About the clutch 18th is one of the internal combustion engine 2nd generated torque, in particular a clutch torque, on the transmission 20 optionally transferable. The gear 20 is designed to use the clutch 18th transmitted torque of the internal combustion engine 2nd with desired gear ratios on an output shaft 28 of the transmission 20 transferred to.

The electrical machine 4th can be operated either as a motor or as a generator. Furthermore, the electrical machine 4th with a crankshaft 24th of the internal combustion engine 2nd , with a gear shaft 26 of the transmission 20 or with the output shaft 28 of the transmission 20 connected. This is schematic with the arrows 4a-d shown. That's one of the electrical machines 4th generated torque in the drive train 1 introductory. The electrical machine preferably acts 4th control side of the internal combustion engine 2nd on the crankshaft 24th , for example via a toothed belt.

2nd shows the control unit 30th as well as the components of the drive train 1 by the control unit 30th are controllable. The control unit 30th is set up to the internal combustion engine 2nd who have favourited electric machine 4th , the exhaust gas turbocharger 6 who have favourited Injector 7 , the second compressor 8th , the actuator assembly 10th or the throttle valve 10a the positioning arrangement 10 ' who have favourited Throttle 17th the exhaust gas recirculation line 16 , the coupling 18th , The gear 20 and the intercooler 22 to control and / or regulate.

The 3a-c show diagrams, the (target and actual) courses of one of the drive train 1 generated drive torque, a lambda value, an air mass, an (fuel) injection quantity, one from the internal combustion engine 2nd generated torque (e.g. clutch torque), one Electric compressor performance 8th and one from the electrical machine 4th represent generated torque.

The 3a shows a diagram of the courses described above without activation of the electrically driven second compressor 8th and the electrical machine 4th . The target drive torque M _{drive, target} is in this case solely on the torque of the internal combustion engine 2nd generated.

As in 3a can be seen, at time I there is a change in the target drive torque M _{drive, target} detected. The actual drive torque also corresponds M _{drive, actual} the target drive torque M _{drive, target} . To the target drive torque M _{drive, target} to achieve a corresponding target fuel quantity m _{F, target} depending on the target drive torque M _{drive, target} determined and injected. The target fuel quantity m _{F, target} is determined, for example, from a map. The injector 7 is designed in such a way that an injection change (including injection quantity, duration, time) takes place essentially immediately. In other words, the actual course of the fuel quantity m _{F, is} corresponds essentially to the target course m _{F, target} . In contrast, the actual air mass gives way m _{L, actual} from that of the internal combustion engine 2nd Target air mass to be supplied m _{L, target} from. This deviation arises, among other things, from the delay in the gas supply, for example from the inertia of the exhaust gas turbocharger 6 . As a result, an actual boost pressure lags behind a target boost pressure. The actual air mass m _{L, actual} therefore falls below the target air mass M _{L, target} .

In the present case it is shown, for example, that the actual air mass m _{L, actual} only after a time III at which the target drive torque M _{drive, target} is reached on the target air mass m _{L, target} is settled.

By falling below the target air mass m _{L, target} is also the target air ratio, that is, the lambda target value λ _target undershot. This is the internal combustion engine 2nd a enriched combustion gas mixture with an actual lambda value λ _is supplied, the combustion of which results in an undesirable increase in emissions, in particular of soot. As from the 3a As can be seen, the duration of a lambda control deviation corresponds essentially until the air mass is adjusted.

In the 3b a diagram is shown in which the electrically driven second compressor 8th to reach the target drive torque M _{drive, target} is operated. So the inertia of the exhaust gas turbocharger 6 and falling below the target air mass as described above m _{L, target} are at least partially compensated. With the support of the exhaust gas turbocharger 6 through the second compressor 8th becomes the target air mass m _{L, target} already reached at a point in time II which lies between the points in time I and III. However, the gas supply delay is due to the inertia of the second compressor 8th and because of the volume or the distance of the gas path, so that the lambda setpoint is still not reached λ _target between time I and II. This shortfall is compared to that in 3a shown shorter and lower, but still leads to increased emissions.

To the in the 3a and 3b To avoid the lambda deviations shown, the injected actual fuel quantity m _{L, actual} be reduced. By observing the lambda setpoint λ _target the emission increases mentioned above can be avoided. However, the reduced amount of fuel also reduces that of the internal combustion engine 2nd generated torque M _VM . The reduced torque M _VM but can by operating the electric drive 4th be compensated at least partially, if not entirely.

So it shows 3c a diagram, the curves of the air mass and fuel quantity and that of the internal combustion engine 2nd and the electrical machine 4th generated torques M _VM , M _EM to the target drive torque M _{drive, target} while maintaining the target lambda value λ _target to reach.

The actual fuel quantity injected m _{F, actual} reduced as long as the air mass has not yet been adjusted, in such a way that the actual fuel quantity m _{F, actual} and the actual air mass m _{L, actual} the Lambda setpoint λ _target to reach. In the 3c this happens between times I and II. Due to the reduced actual fuel quantity m _{F, actual} is that from the internal combustion engine 2nd generated torque M _VM correspondingly smaller in this period. This torque reduction is due to the operation of the electrical machine 4th compensated. In other words, the electrical machine 4th is operated as a function of a fuel quantity control deviation, in particular in such a way that a torque change of the internal combustion engine resulting from the fuel quantity control deviation 2nd (at least partially and preferably completely) is compensated.

Between times I and II there is a time I 'from which the actual air mass m _{L, actual} the target air mass m _{L, target} approximates. The actual fuel quantity is correspondingly m _{F, actual} to the actual air mass m _{L, actual} adjusted, which also changes the torque M _VM elevated. Therefore, this can be done by the electrical machine 4th generated torque MEM corresponding to the torque M _VM be reduced to the target drive torque M _{drive, target} to reach.

At time II the actual air mass is reached m _{L, actual} the target air mass m _{L, target} and the amount of fuel injected m _{F, actual} can on the target fuel quantity m _{F, target} be set to the internal combustion engine 2nd must be supplied so that the target drive torque M _{drive, target} generated alone. As a result, from time II, the electric machine can contribute to the drive torque 4th generated torque can be reduced to zero. The second compressor 8th will continue to operate since (as from 3a visible) the exhaust gas turbocharger 6 the target air mass only after time III m _{L, target} the internal combustion engine 2nd can supply. The second compressor 8th continues to operate, particularly between times II and III, to regulate the air mass. The performance of the second compressor 8th is then continuously lowered until time III, so that its performance is zero from time III.

The 4th shows a sequence of a method for controlling the drive train 1 . The target drive torque is set in S1 M _{drive, target} detected by the powertrain 1 should be generated. In S2 becomes the Lambda setpoint λ _target depending on the target drive torque M _{drive, target} certainly. In S3 becomes the target fuel quantity m _{F, target} of the fuel determined to reach the target drive torque M _{drive, target} is required. In S4 is through the air line 5 Air mass supplied taking the lambda setpoint into account λ _target set. Because the Lambda setpoint λ _target the target air mass results m _{L, target} , so that a combustion gas mixture consisting of the air mass and fuel quantity achieves the required quality, ie ratio of air and fuel, and thus the combustion engine 2nd the target drive torque M _{drive, target} can generate. However, the regulation of the air mass is subject to the delay described above, so that the actual air mass m _{L, actual} the target air mass m _{L, target} lagging behind, so falling short. So in S5 the actual lambda value becomes λ _actual determined from the actual air mass m _{L, actual} and the determined target fuel quantity _{mF, should be} determined. From this, a lambda control deviation can then be determined, which results from a difference between the desired lambda value and the actual lambda value. In S6 this lambda control deviation is corrected by adjusting the fuel supply. The fuel supply is adjusted in such a way that the actual fuel quantity m _{F, actual} to the actual air mass m _{L, actual} is adjusted so that the lambda control deviation is minimized as much as possible. A torque change of the internal combustion engine resulting from the correction of the lambda control deviation 2nd (because of the comparatively lower actual fuel quantity m _{F, actual} ) is by the electrical machine 4th compensated so that the powertrain 1 the target drive torque M _{drive, target} can generate.

Reference list

1

Powertrain

2nd

Internal combustion engine

4th

electric motor

5

Air duct

6

Exhaust gas turbocharger

6a

first compressor

6b

turbine

7

Injector

8th

second compressor

10th

3-way control valve

10 '

throttle

15

Exhaust pipe

16

Exhaust gas recirculation line (EGR)

17th

EGR throttle valve

18th

coupling

20

transmission

22

Intercooler

24th

crankshaft

26

Gear shaft

28

Output shaft (gear)

30th

Control unit

M _{drive, target}

Target drive torque

M _VM

Torque (internal combustion engine)

M _EM

Torque (electric machine)

m _{L, actual}

Actual air mass

m _{L, target}

Target air mass

m _{F, actual}

Actual fuel quantity

m _{F, target}

Target fuel quantity

λ _actual

Actual lambda value

λ _target

Lambda setpoint

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 19708721 A1 [0003]
• DE 102008041566 A1 [0006]

Claims (10)

Method for controlling a drive train (1) of a vehicle (100) which has an internal combustion engine (2) with an electrically assisted engine charging system (6, 8) and a further drive motor in the form of an electrical machine (4), comprising: (S1) detection a target drive torque (M _{drive, target} ) to be generated by the drive train (1); (S2) determining a lambda target value (λ _target ) as a function of the target drive torque (M _{drive, target} ); (S3) determining a fuel supply (m _{F, target} ) to achieve the target drive torque (M _{drive, target} ); (S4) adjusting a gas supply (m _{L, target} ) with the aid of the electrically assisted engine charging system, taking into account the lambda target value (λ _target ); (S5) determining an _actual lambda value (λ _actual ) taking into account the determined fuel supply (m _{F, target} ); (S6) correcting a lambda control deviation by adapting the fuel supply (m _{F, actual} ); and (S7) compensating for a change in torque of the internal combustion engine (2) resulting from the correction of the lambda control deviation by the electrical machine (4) in order to achieve the target drive torque (M _{drive, target} ). Procedure according to Claim 1 , wherein the correction of the lambda control deviation takes place in such a way that the lambda control deviation is in an allowed interval. Procedure according to one of the Claims 1 or 2nd The electrically assisted engine supercharging system comprises an exhaust gas turbocharger (6) with a first compressor (6a) and an electrically driven second compressor (8). Procedure according to Claim 3 , wherein the second compressor (8) is arranged downstream of the first compressor (6a) of the exhaust gas turbocharger (6). Procedure according to Claim 3 or 4th , wherein the second compressor (8) is operated as long as the lambda control deviation is present. Procedure according to one of the Claims 3 to 5 A feed line of the second compressor (8) branches off from an air path (5) of the internal combustion engine (2) and a discharge line of the second compressor (8) opens into the air path (5) downstream of the branch. Procedure according to Claim 6 A gas supply to the internal combustion engine (2) from the first compressor (6a) and the second compressor (8) can be set via an actuating arrangement (10; 10 ') Procedure according to one of the Claims 1 to 7 The electrical machine (4) is coupled to an output shaft (28) of a transmission (20) of the drive train (1), a transmission shaft (26) of the transmission (20) or to a crankshaft (24) of the internal combustion engine (2). Control device (30) for a drive train (1) of a vehicle, which is designed to carry out the method according to one of the preceding claims. Vehicle (100) with a control device according to Claim 9 whose drive train (1) according to the method according to one of the Claims 1 to 8th is controllable.

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