DE102017119906A1 - Method for operating a hybrid powertrain, control unit and motor vehicle - Google Patents

Abstract

The invention relates to a method for operating a hybrid drive train (1) of a motor vehicle (2) having a control unit (3) for controlling the drive train (1), wherein the drive train (1) comprises an internal combustion engine (4), a shiftable transmission (5). a first electric machine (6) and a second electric machine (7), wherein the first electric machine (6) and the internal combustion engine (4) are arranged on an input side of the switchable transmission (5), and wherein the second electric machine (7) an output side of the switchable transmission (5) is arranged. According to the method, a plurality of operating parameters of the motor vehicle (2) are determined, derived therefrom different torque distribution criteria (8, 9, 10, 11) and determined on this basis, a torque distribution between the first electric machine (6) and the second electric machine (7). Furthermore, the invention relates to a control unit (3) and a motor vehicle (2).

Description

The present invention relates to a method for operating a hybrid drive train of a motor vehicle having a control unit for controlling the drive train, wherein the drive train comprises an internal combustion engine, a shiftable transmission, a first electric machine and a second electric machine. Furthermore, the method relates to a control unit for a motor vehicle for controlling a hybrid drive train. Finally, the invention relates to a motor vehicle with a hybrid drive train.

There are known hybrid vehicles, which have at least two electric machines which are operable as electric motors. Such a vehicle concept is for example in the DE 10 2015 206 190 A1 disclosed. During operation of such a hybrid vehicle, different operating conditions, such as boost, instation equalization or load point shift, may occur. Boosting is an operating state in which at least one electric machine is operated as an electric motor and provides an additional drive torque for the drive torque of the internal combustion engine. In Instationärausgleich higher dynamics of at least one electric machine is used to compensate for lower dynamics of the internal combustion engine, for example, in a sudden power request or when temporarily switching off the internal combustion engine to improve a Rekuperationseffizienz or to accelerate enabling a purely electric drive. For example, load point shift includes load point boost. When the load point is increased by the internal combustion engine, a drive torque and an additional torque provided, which is converted by at least one operated as a generator electric machine into electrical energy, eg for charging an electrical energy storage of the vehicle.

This results in the problem of distributing a torque to be applied or to be absorbed by the entirety of the electric machines in these operating states described above particularly advantageously to the at least two electric machines. For this purpose, it is necessary to define decision criteria according to which the torque to be generated from electrical energy or to be absorbed to generate electrical energy is distributed between the at least two electric machines. With such a distribution, within the scope of the invention the individual electric machines can preferably be assigned between 0% and 100% of the torque to be distributed.

It is known, for example, to carry out such a torque distribution upon charging request or load point shift on the basis of efficiency considerations. The focus of such an efficiency consideration can be, for example, a cost-benefit analysis, an energy balance, an environmental audit or the like.

Known methods for operating a hybrid drive train with at least two electric motors have the disadvantage that, due to lack of distribution criteria, driving situations can occur which, for example, shorten a component's service life, adversely affect driving comfort or impair driving dynamics.

It is therefore the object of the present invention to provide a method for operating a hybrid drive train of a motor vehicle, a control unit for a motor vehicle for controlling a hybrid drive train and a motor vehicle with a hybrid drive train, which do not have the disadvantages of the prior art described above or at least partially fix it. In particular, it is an object of the present invention to provide a method for operating a hybrid drive train of a motor vehicle, a control unit for a motor vehicle for controlling a hybrid drive train and a motor vehicle with a hybrid drive train, in a simple and cost-effective manner, a torque distribution to at least improve two electric motors.

The above problem is solved by the claims. Accordingly, the object is achieved by a method having the features of claim 1, by a control unit having the features of claim 9 and by a motor vehicle having the features of claim 10. Further features and details of the invention will become apparent from the dependent claims, the description and the drawings. In this case, features and details that are described in connection with the inventive method, of course, also in connection with the control unit according to the invention and the motor vehicle according to the invention and in each case vice versa, so that with respect to the disclosure of the individual aspects of the invention always reciprocal reference is or may be.

• - Ermitteln mindestens eines ersten Betriebsparameters des Kraftfahrzeugs mittels der Steuerungseinheit, wobei der mindestens eine erste Betriebsparameter eine Betriebsbelastung der ersten Elektromaschine und/oder der zweiten Elektromaschine beeinflusst,
• - Ableiten eines ersten Drehmomentverteilungskriteriums mittels der Steuerungseinheit auf Basis des ermittelten mindestens einen ersten Betriebsparameters und einer vorgegebenen Betriebsbelastungsgrenze der ersten Elektromaschine und/oder der zweiten Elektromaschine in Bezug auf den mindestens einen ermittelten ersten Betriebsparameter,
• - Ermitteln mindestens eines zweiten Betriebsparameters des Kraftfahrzeugs mittels der Steuerungseinheit, wobei der mindestens eine zweite Betriebsparameter ein Fahrkomfortverhalten des Kraftfahrzeugs beeinflusst,
• - Ableiten eines zweiten Drehmomentverteilungskriteriums mittels der Steuerungseinheit auf Basis des ermittelten mindestens einen zweiten Betriebsparameters und einer vorgegebenen Fahrkomfortvorgabe des Kraftfahrzeugs in Bezug auf den mindestens einen ermittelten zweiten Betriebsparameter,
• - Ermitteln mindestens eines dritten Betriebsparameters des Kraftfahrzeugs mittels der Steuerungseinheit, wobei der mindestens eine dritte Betriebsparameter einen Betriebszielzustand des Antriebsstrangs definiert,
• - Ableiten eines dritten Drehmomentverteilungskriteriums mittels der Steuerungseinheit auf Basis des ermittelten mindestens einen dritten Betriebsparameters und einer Zielzustandsvorgabe des Antriebsstrangs in Bezug auf den mindestens einen ermittelten dritten Betriebsparameter, und
• - Bestimmen einer Drehmomentverteilung zwischen der ersten Elektromaschine und der zweiten Elektromaschine mittels der Steuerungseinheit auf Basis des ersten Drehmomentverteilungskriteriums, des zweiten Drehmomentverteilungskriteriums und des dritten Drehmomentverteilungskriteriums.

According to a first aspect of the invention, the object is achieved by a method for operating a hybrid drive train of a motor vehicle. The motor vehicle has a control unit for controlling the drive train. The hybrid powertrain includes an internal combustion engine, a shiftable transmission, a first electric machine and a second electric machine, wherein the the first electric machine and the internal combustion engine are arranged on an input side of the shiftable transmission, and wherein the second electric machine is arranged on an output side of the shiftable transmission. The method according to the invention comprises the following steps:

• Determining at least one first operating parameter of the motor vehicle by means of the control unit, wherein the at least one first operating parameter influences an operating load of the first electric machine and / or the second electric machine,
• Deriving a first torque distribution criterion by means of the control unit on the basis of the determined at least one first operating parameter and a predetermined operating load limit of the first electric machine and / or the second electric machine with respect to the at least one determined first operating parameter,
• Determining at least one second operating parameter of the motor vehicle by means of the control unit, wherein the at least one second operating parameter influences a driving comfort behavior of the motor vehicle,
• Deriving a second torque distribution criterion by means of the control unit on the basis of the determined at least one second operating parameter and a predetermined driving comfort specification of the motor vehicle with respect to the at least one determined second operating parameter,
• Determining at least one third operating parameter of the motor vehicle by means of the control unit, wherein the at least one third operating parameter defines an operating target state of the drive train,
• Deriving a third torque distribution criterion by means of the control unit on the basis of the determined at least one third operating parameter and a target state specification of the drive train with respect to the at least one determined third operating parameter, and
• - Determining a torque distribution between the first electric machine and the second electric machine by means of the control unit based on the first torque distribution criterion, the second torque distribution criterion and the third torque distribution criterion.

First, at least one first operating parameter of the motor vehicle is determined. The first operating parameter influences the operating load of the first electric machine and / or the second electric machine. This means in particular that the operating load of the first electric machine and / or the second electric machine can at least be increased by the first operating parameter. The determination of the first operating parameter can be carried out, for example, by measuring or reading out a stored ACTUAL value or identifying a SETPOINT specification by means of the control unit. Possible first operating parameters may be, for example, a rotational speed, a torque, a speed, an accelerator pedal position, a temperature or the like. Preferably, in particular the first operating parameter of the second electric machine is determined. More preferably, a plurality of first operating parameters are determined. More preferably, at least one first operating parameter is determined, which influences the operating load of the first electric machine, and determines at least one first operating parameter, which influences the operating load of the second electric machine.

The first torque distribution criterion is then derived by means of the control unit. For this purpose, a predetermined operating load limit of the first electric machine or of the second electric machine is determined with respect to the at least one first operating parameter. The operating load limit designates, for example, a maximum value which the first operating parameter may assume in order to still avoid excessive wear or damage to the second electric machine. By defining an operating load limit, a minimum service life of the second electric machine can thus be ensured. Exceeding the operating load limit, in particular exceeding it over a relatively long period of time, is therefore preferably to be avoided since this can shorten the service life of the second electric machine. The torque distribution criterion takes this requirement into account and will assign the second electric machine, preferably a maximum, such a torque proportion that exceeding the operating load limit does not occur or is prevented as far as possible. In the event that no reaching the operating load limit threatens, the first torque distribution criterion may for example be designed such that thereby a distribution bandwidth is set, within which a safe operation of the second electric machine is possible. In this case, the second electric machine may e.g. a torque share between 0% and x% are released, for example, from a share of x% may threaten an overload of the second electric machine.

Furthermore, at least one second operating parameter of the motor vehicle is determined by means of the control unit. This determination can for example be simultaneous or substantially be carried out simultaneously or with a time delay with the determination of the at least one first operating parameter. The second operating parameter influences a driving comfort behavior, such as vibrations, jerking or the like, of the motor vehicle. The determination of the second operating parameter can be carried out, for example, by measuring or reading out a stored ACTUAL value or identifying a SETPOINT specification by means of the control unit. Possible second operating parameters may be, for example, a rotational speed, a torque, a speed, an accelerator pedal position, a gear selection of the transmission or the like.

Subsequently, the second torque distribution criterion is derived by means of the control unit. In this case, a predetermined driving comfort specification is determined by the control device. The driving comfort specification defines a target, the achievement of which depends directly or at least indirectly on a design of the second operating parameter. The ride comfort specification may be determined, for example, by the driver, e.g. by deliberately choosing an economy, comfort, sports mode or the like. Negatively affect the ride comfort, for example, vibration, jerking or the like of the motor vehicle. For a high level of ride comfort, e.g. in comfort mode, vibrations and jerking are preferably to be reduced; in sports mode, for example, stronger vibrations or jerking, e.g. be allowed to provide a realistic as possible driving experience.

Furthermore, at least one third operating parameter of the motor vehicle is determined by means of the control unit. This determination can be carried out, for example, simultaneously or essentially simultaneously or with a time delay with the determination of the at least one first operating parameter or of the at least one second operating parameter. The third operating parameter determines the operating target state of the powertrain. This means that, based on the third operating parameter, it can be recognized which operating target state the drive state will subsequently assume. An operation target state is, for example, an uncoupled internal combustion engine. The determination of the third operating parameter can be carried out, for example, by measuring or reading out a stored actual value or identifying a target specification by means of the control unit. Possible third operating parameters may be, for example, a rotational speed, a torque, a speed, an accelerator pedal position, a gear selection of the transmission or the like.

The control unit then derives the third torque distribution criterion. For this purpose, the control unit first determines a destination state specification which describes a target operating state of the drive train to be reached. A target state specification is, for example, switching off the internal combustion engine for subsequent electric drive, recuperation or the like. The destination state specification can be predetermined, for example, ex works and / or the workshop and stored in a memory unit of the motor vehicle. The third operating parameter therefore preferably describes an event by which the target state specification is determined. The third operating parameter can be, for example, such a deceleration of the motor vehicle to a speed, so that switching off the internal combustion engine is advantageous for example from an economic point of view. Depending on the target state specification and the third operating parameter, the control unit derives the third torque criterion. In the present case of an intended shutdown of the internal combustion engine, a negative Instationärausgleich by an electric machine is advantageous. Since when switching off the internal combustion engine, a clutch to the transmission is only opened when it is free of load or torque, a negative Instationärausgleich is instructed by at least one electric machine to compensate for the lost torque from the engine for this process. This negative Instationärausgleich is preferably carried out by the first electric machine, since a torque transmission from the second electric machine via the clutch and the transmission takes place to the engine, which would cause a prolonged stop duration of the internal combustion engine.

Subsequently, taking into account the first torque distribution criterion, the second torque distribution criterion and the third torque distribution criterion, the control unit determines the preferred torque distribution between the first electric machine and the second electric machine. Is distributed in the context of the invention, the torque which is to be provided by the electric machines of the motor vehicle. For two electric machines, with an assigned torque share for the first electric machine of y%, the assigned torque share of the second electric machine is (100-y)%.

An inventive method for operating a hybrid drive train of a motor vehicle has the advantage over conventional methods that a torque distribution is provided by simple means and in a cost-effective manner by means of which component stresses can be reduced, driving characteristics improved and operating target states of the motor vehicle can be achieved faster.

According to a preferred development of the invention, it can be provided in a method that the first operating parameter is a Operating temperature of the second electric machine is determined. An operating limit of an electric machine can be determined via its operating temperature. From a limit temperature, rising temperatures lead to increased wear and thus to a reduced service life of an electric machine. The operating load limit accordingly denotes a maximum permissible operating temperature. By using the operating temperature as the first operating parameter and comparing the operating temperature with the operating load limit, it is thus possible to determine whether the second electric machine permits a further increase in the operating temperature and, for example, can continue to be actuated or if the second electric machine must be relieved so that the operating temperature does not continue increases or at least does not exceed the operating load limit. In addition or as an alternative to the operating temperature, a gradient of the operating temperature can be used as the first operating parameter. Such a first operating parameter has the advantage that it is easily ascertainable, in particular measurable, and that an operating load of the second electric machine can be reliably specified.

It is inventively preferred that a switching state of the transmission is determined as a second operating parameter. As a switching state is referred to in the context of the invention, for example, a selected gear or a gear change of the shiftable transmission. During a gear change, an instation equalization by the second electric machine is preferred according to the invention since, during the gear change, a drive torque which can be transmitted from the combustion engine and from the first electric machine to a drive axle of the motor vehicle is reduced. By Instationärausgleich thus a short-term thrust loss can be reduced. It is inventively preferred that during a gear change no redistribution of torque between the first electric machine and the second electric machine takes place. In other words, an already existing torque distribution during the gear change is not changed. A selected gear plays a special role especially when a low gear, in particular the 1st, 2nd or 3rd gear, or a particularly large gear ratio of the transmission is selected. In this state, a redistribution between the first electric machine and the second electric machine, in particular with a high redistribution rate, disadvantageous because a large translation leads to inaccuracies in the transmission behavior to larger torque errors on the wheel. Accordingly, in the case of large ratios, no or at most a slow rate of redistribution of the torque between the first electric machine and the second electric machine is preferred. This can reduce jerking of the vehicle and thus the ride comfort can be significantly improved.

Further preferably, an accelerator pedal position and / or propulsion input of a speed control system of the motor vehicle is determined as the third operating parameter. By means of the determination of the accelerator pedal position or the propulsion input of the speed control system, an operating state can be accurately determined in which a shutdown of the internal combustion engine is imminent or is to be carried out. Thus, a redistribution of the torque by means of the control unit can be so Induced that the discharge or torque freedom of the clutch is preferably carried out by the first electric machine. It is preferred that, in this context, a vehicle speed is also taken into account as a third operating parameter, since a shutdown of the internal combustion engine, in particular at lower speeds, e.g. within a city or in stop-and-go journeys or the like, is advantageous and is therefore instructed by the control unit.

In a particularly preferred embodiment of the method according to the invention, the torque distribution criteria are prioritized. In the context of the invention, a prioritization can be understood as an order of consideration and / or a weighting of the torque distribution criteria. It is inventively preferred that a specific torque distribution criterion can assume a value that overrules the other torque distribution criteria. Preferably, the highest priority can be assigned to the first torque distribution criterion, so that a component overload of the second electric machine is avoided in any case. According to the invention, the second torque distribution criterion may be prioritized higher than the third torque distribution criterion, e.g. if a ride comfort is given greater importance than a driving dynamics. Alternatively, it can be provided in the context of the invention that the third torque distribution criterion is prioritized higher than the second torque distribution criterion, in particular if a high driving dynamics is more important than the driving comfort. A prioritization has the advantage that a needs-based torque distribution is thus further improved.

Preferably, at least one fourth operating parameter of the motor vehicle is determined by means of the control unit, wherein a fourth torque distribution criterion is derived by means of the control unit on the basis of the determined at least one fourth operating parameter and a predetermined efficiency specification with respect to the at least one determined fourth operating parameter. This determination can be carried out, for example, simultaneously or substantially simultaneously or with a time delay with the determination of the at least one first operating parameter or of the at least one second operating parameter or the at least one third operating parameter. The determination of the fourth operating parameter can be carried out, for example, by measuring or reading out a stored actual value or identifying a target input by means of the control unit. Possible fourth operating parameters may be, for example, a rotational speed, a torque, a speed, an accelerator pedal position, a gear selection of the transmission, an operating temperature or the like. The efficiency specification can take into account, for example, a low energy consumption and / or a favorable power transmission. In this way, a particularly economical operation of the hybrid drive train is favored. In the case of prioritizing the torque distribution criteria, the fourth torque distribution criterion is preferably assigned a lower priority than the first torque distribution criterion.

It is inventively preferred that the at least one first operating parameter and / or the at least one second operating parameter and / or the at least one third operating parameter is determined by prediction. In this case, for example, a profile of the respective operating parameter can be considered and compared with further operating parameters. If, for example, the operating temperature of the second electric machine is selected as the first operating parameter and an imminent electric drive is predicted, the first torque distribution criterion could be derived such that the second electric machine is already allocated a lower torque proportion early, if possible to at least the second electric machine from the operating temperature To keep low and thus allow greater use of the second electric machine for the upcoming electric drive. A prediction of operating parameters has the advantage that the torque distribution can already be anticipatory. A redistribution of torque between the electric machines is thus already possible, for example, early before a gear change.

More preferably, a route history of the motor vehicle or a route predefined by a navigation system of the motor vehicle is used for the prediction of at least one operating parameter. Preferably, additionally current traffic information can be taken into account. Use of the route history is particularly advantageous if regularities of the routes traveled, such as Job paths with commuters, are recognizable. Routes predefined by a navigation system have the advantage that they usually allow very reliable predictions about the route which the motor vehicle will drive. The consideration of route data in the prediction has the advantage that already on the basis of a route, prospective operating states of the motor vehicle, such as e.g. electric driving, stopping times at traffic lights, speed limits, fast highway driving and the like, are reliably predictable.

According to a second aspect of the invention, the object is achieved by a control unit for a motor vehicle for controlling a hybrid drive train of the motor vehicle. The powertrain has an internal combustion engine, a shiftable transmission, a first electric machine and a second electric machine. The first electric machine and the internal combustion engine are preferably arranged on an input side of the shiftable transmission. The second electric machine is preferably arranged on an output side of the shiftable transmission. According to the invention, the control unit comprises a computing unit and a memory unit. In the memory unit, a program is stored, which performs an inventive method in at least partial execution in the arithmetic unit.

In the described control unit, all the advantages that have already been described for a method according to the first aspect of the invention. Accordingly, the control unit according to the invention has the advantage that with simple means and in a cost effective manner, a torque distribution can be provided by means of which component stresses reduced, improved driving characteristics and operating target states of the motor vehicle can be achieved faster.

According to a third aspect of the invention, the object is achieved by a motor vehicle having a hybrid drive train. The powertrain has an internal combustion engine, a shiftable transmission, a first electric machine and a second electric machine. The first electric machine and the internal combustion engine are preferably arranged on an input side of the shiftable transmission. The second electric machine is preferably arranged on an output side of the shiftable transmission. Preferably, the motor vehicle has an energy store for receiving and for providing electrical energy for operating the first electric machine and / or the second electric machine. The motor vehicle has a control unit according to the invention.

In the motor vehicle described, all the advantages that have already been described for a method according to the first aspect of the invention and the control unit according to the invention according to the second aspect of the invention. Accordingly, that has Motor vehicle according to the invention has the advantage that with simple means and in a cost effective manner a torque distribution can be provided by means of which component stresses can be reduced, driving characteristics improved and operating target states of the motor vehicle can be achieved faster.

• 1 in einem Ablaufdiagramm eine bevorzugte Ausführungsform des erfindungsgemäßen Verfahrens,
• 2 eine Zusammenschau mehrerer Drehmomentverteilungskriterien,
• 3 in einer Seitenansicht eine bevorzugte Ausführungsform eines erfindungsgemäßen Kraftfahrzeugs, und
• 4 in einer Draufsicht eine bevorzugte Ausführungsform einer erfindungsgemäßen Steuerungseinheit.

An inventive method, a control unit according to the invention and a motor vehicle according to the invention are explained in more detail with reference to drawings. Each show schematically:

• 1 in a flow chart a preferred embodiment of the method according to the invention,
• 2 a synopsis of several torque distribution criteria,
• 3 in a side view of a preferred embodiment of a motor vehicle according to the invention, and
• 4 in a plan view, a preferred embodiment of a control unit according to the invention.

Elements with the same function and mode of action are in the 1 to 4 each provided with the same reference numerals.

In 1 an inventive method is shown schematically in a flow chart. The components of the motor vehicle involved in the implementation of the method 2 are in particular in 3 shown. In a first process step 100 determines the control unit 3 at least one first operating parameter of the motor vehicle 2 , such as an operating temperature and / or an operating temperature gradient of the second electric machine 7 , In a second process step 200 directs the control unit 3 from the first operating parameter and a predetermined operating load limit, a first torque distribution criterion 8th from. In a third process step 300 determines the control unit 3 at least one second operating parameter of the motor vehicle 2 , such as a set gear or a gear change of the transmission 5 , In a fourth process step 400 directs the control unit 3 from the second operating parameter and a predetermined driving comfort specification, a second torque distribution criterion 9 from. In a fifth process step 500 determines the control unit 3 at least one third operating parameter of the motor vehicle 2 such as an accelerator pedal position and / or a speed and / or an acceleration or deceleration of the motor vehicle 2 , In a sixth process step 600 directs the control unit 3 from the third operating parameter and a predetermined target state specification of the drive train 1 a third torque distribution criterion 10 from. In a seventh process step 700 determines the control unit 3 a torque distribution based on the first torque distribution criterion 8th , the second torque distribution criterion 9 and the third torque distribution criterion 10 ,

2 shows a synopsis of several torque distribution criteria ( 8th . 9 . 10 . 11 ) in bar charts. The bars shown range from 0% to 100%, with 0% representing a complete distribution of torque to the first electric machine 6 and 100% a complete distribution of torque on the second electric machine 7 means. The shaded areas denote torque components, which according to the respective torque distribution criterion ( 8th . 9 . 10 . 11 ) of the second electric machine 7 should not be assigned. The white areas indicate possible torque components that are determined according to the respective torque distribution criterion ( 8th . 9 . 10 . 11 ) of the second electric machine 7 to be assigned. According to the first torque distribution criterion 8th becomes the second electric machine 7 assigned in this example a torque share between 0% and 40%. For example, with a torque share higher than 40%, the second electric machine could overheat 7 threatening. According to the second torque distribution criterion 9 becomes the second electric machine 7 Assigned a torque share between 20% and 80% in this example. According to the third torque distribution criterion 10 becomes the second electric machine 7 Assigned a torque share of 0% in this example. According to the fourth torque distribution criterion 11 becomes the second electric machine 7 Assigned a torque share of 100% in this example. Preferably, the first torque distribution criterion 8th prioritized such that a maximum possible torque allocation for the second electric machine 7 by the first torque distribution criterion 8th is fixed. Consequently, the second electric machine 7 potentially assigned between 0% and 40%. In the event that the second torque distribution criterion 9 Assigning a second highest prioritization could, for example, set the potential torque allocation between 20% and 40%. At a second highest prioritization of the third torque distribution criterion 10 , would the torque allocation for the second electric machine 7 0% in this example. According to the fourth torque distribution criterion 11 would the second electric machine 7 100% of the torque will be allocated in this example. However, this allocation would not be instructed since such allocation would be with the first torque distribution criterion 8th would collide.

In 3 is a preferred embodiment of a motor vehicle according to the invention 2 shown schematically in a side view. The components of the motor vehicle described below 2 are indicated in the drawing by dashed rectangles and can in the context of the invention also different on the motor vehicle 2 be arranged. The car 2 has a control unit 3 as well as a hybrid powertrain 1 with an internal combustion engine 4 , a switchable transmission 5 , a clutch 14 , a first electric machine 6 and a second electric machine 7 on. The internal combustion engine 4 and the first electric machine 6 are about the clutch 14 with a transmission input of the transmission 5 mechanically coupled. The second electric machine 7 is for example with a wheel 15 of the motor vehicle 2 mechanically coupled.

4 shows a preferred embodiment of a control unit according to the invention 3 schematically in a plan view. The control unit 3 has an arithmetic unit 12 and a storage unit 13 on.

LIST OF REFERENCE NUMBERS

1

powertrain

2

motor vehicle

3

control unit

4

internal combustion engine

5

transmission

6

first electric machine

7

second electric machine

8th

first torque distribution criterion

9

second torque distribution criterion

10

third torque distribution criterion

11

fourth torque distribution criterion

12

computer unit

13

storage unit

14

clutch

15

wheel

100

first process step

200

second process step

300

third process step

400

fourth process step

500

fifth process step

600

sixth process step

700

seventh process step

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely 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.

Cited patent literature

• DE 102015206190 A1 [0002]

Claims (10)

Method for operating a hybrid drive train (1) of a motor vehicle (2) with a control unit (3) for controlling the drive train (1), wherein the drive train (1) comprises an internal combustion engine (4), a shiftable transmission (5), a first electric machine (6) and a second electric machine (7), wherein the first electric machine (6) and the internal combustion engine (4) are disposed on an input side of the switchable transmission (5), and wherein the second electric machine (7) is on an output side of the switchable Gearbox (5) is arranged, comprising the following steps: Determining at least one first operating parameter of the motor vehicle (2) by means of the control unit (3), the at least one first operating parameter influencing an operating load of the first electric machine (6) and / or the second electric machine (7), - Deriving a first torque distribution criterion (8) by means of the control unit (3) based on the determined at least a first operating parameter and a predetermined operating load limit of the first electric machine (6) and / or the second electric machine (7) with respect to the at least one determined first operating parameter . Determining at least one second operating parameter of the motor vehicle (2) by means of the control unit (3), wherein the at least one second operating parameter influences a driving comfort behavior of the motor vehicle (2), Deriving a second torque distribution criterion (9) by means of the control unit (3) on the basis of the determined at least one second operating parameter and a predetermined driving comfort specification of the motor vehicle (2) with respect to the at least one determined second operating parameter, Determining at least one third operating parameter of the motor vehicle (2) by means of the control unit (3), wherein the at least one third operating parameter defines an operating target state of the drive train (1), Deriving a third torque distribution criterion (10) by means of the control unit (3) on the basis of the determined at least one third operating parameter and a target state specification of the drive train (1) with respect to the at least one determined third operating parameter, and - Determining a torque distribution between the first electric machine (6) and the second electric machine (7) by means of the control unit (3) based on the first torque distribution criterion (8), the second torque distribution criterion (9) and the third torque distribution criterion (10). Method according to Claim 1 , characterized in that an operating temperature of the second electric machine (7) is determined as the first operating parameter. Method according to Claim 1 or 2 , characterized in that a switching state of the transmission (5) is determined as the second operating parameter. Method according to one of the preceding claims, characterized in that an accelerator pedal position and / or propulsion input of a speed control system of the motor vehicle (2) is determined as the third operating parameter. Method according to one of the preceding claims, characterized in that a prioritization of the torque distribution criteria (8, 9, 10) takes place. Method according to one of the preceding claims, characterized in that at least a fourth operating parameter of the motor vehicle (2) by means of the control unit (3) is determined, and that a fourth torque distribution criterion (11) by means of the control unit (3) based on the determined at least a fourth Operating parameters and a predetermined efficiency specification with respect to the at least one determined fourth operating parameters is derived. Method according to one of the preceding claims, characterized in that the at least one first operating parameter and / or the at least one second operating parameter and / or the at least one third operating parameter are determined by prediction. Method according to Claim 7 , characterized in that a route history and / or a route predefined by a navigation system of the motor vehicle (2) are used for the prediction. Control unit (3) for a motor vehicle (2) for controlling a hybrid drive train (1) of the motor vehicle (2), wherein the drive train (1) comprises an internal combustion engine (4), a shiftable transmission (5), a first electric machine (6) and a second electric machine (7), characterized in that the control unit (3) comprises a computing unit (12) and a memory unit (13) and in the memory unit (13) a program is stored, which at at least partially execution in the arithmetic unit (12) a method according to one of Claims 1 to 8th performs. Motor vehicle (2) with a hybrid drive train (1), wherein the drive train (1) an internal combustion engine (4), a switchable transmission (5), a first electric machine (6) and a second electric machine (7), characterized in that the motor vehicle (2) according to a control unit (3) Claim 9 having.

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