DE102018221467A1 - Method for operating a drive device - Google Patents

Abstract

The invention relates to a method for operating a drive device (10), in particular in a motor vehicle, comprising an internal combustion engine (12) and at least one further drive unit (28), which is not an internal combustion engine (12), an exhaust gas from the internal combustion engine (12) being used of an exhaust gas aftertreatment system (16), characterized in that a check is carried out to determine whether the internal combustion engine (12) is in an operating point which is defined as favorable for the diagnosis of the exhaust gas aftertreatment, and when it is determined that the internal combustion engine (12) is not located in an operating point defined as favorable for the diagnosis of exhaust gas aftertreatment, the operating point of the internal combustion engine (12) is brought into an area defined as favorable for the exhaust gas aftertreatment using the further drive unit (28). The invention further relates to a control and / or regulating device (44) for a motor vehicle, which is set up to carry out the method.

Description

State of the art

The invention relates to a method for operating a drive device, in particular in a motor vehicle, comprising an internal combustion engine and at least one further drive unit, which is not an internal combustion engine, an exhaust gas of the internal combustion engine being treated by means of an exhaust gas aftertreatment system. In addition, the invention relates to a control and / or regulating device and a computer program according to the independent claims.

Motor vehicles, in particular diesel vehicles, are known from the market which have an exhaust gas aftertreatment system which comprises, for example, an SCR catalytic converter (SCR means “selective catalytic reduction”). This makes it possible to reduce nitrogen oxides (NOx) in the exhaust gas. Depending on an operating state of an internal combustion engine of the motor vehicle, a temperature of the exhaust gas or the SCR catalytic converter, and on other parameters, the reduction in nitrogen oxides (“NOx conversion”) can be different.

Disclosure of the invention

The problem underlying the invention is solved by a method according to claim 1, and by a control and / or regulating device and a computer program according to the independent claims. Advantageous further developments are specified in the subclaims. Features important for the invention can also be found in the following description and in the drawings, the features being important for the invention both on their own and in different combinations, without being explicitly mentioned again.

The method according to the invention has the advantage that in a motor vehicle with a so-called hybrid drive, preferably a combination of an internal combustion engine and an electric motor, which can preferably be operated as a generator and / or motor, favorable operating conditions for diagnosis of the exhaust gas aftertreatment system are particularly good, reliable and can be set to be planned. This means that a diagnosis can be carried out without an interruption, which is necessary, for example, to adapt the operating points of the internal combustion engine as a result of external circumstances. An operating temperature of an exhaust gas aftertreatment system - in particular a catalytic converter - of the internal combustion engine and / or a proportion of raw NOx emissions in the exhaust gas and a load of the internal combustion engine can be optimally set within the system-related limits.

The invention relates to a method for operating a drive device, in particular in a motor vehicle, comprising an internal combustion engine and at least one further drive unit, which is not an internal combustion engine, an exhaust gas of the internal combustion engine being treated by means of an exhaust gas aftertreatment system. The exhaust gas aftertreatment system comprises at least one exhaust gas catalytic converter. According to the invention, it is checked whether the internal combustion engine is in an operating point that is defined as favorable for the diagnosis of exhaust gas aftertreatment. If it is determined that the internal combustion engine is not in an operating point that is defined as favorable for the diagnosis of exhaust gas aftertreatment, then the operating point of the internal combustion engine is brought into a range that is defined as favorable for exhaust gas aftertreatment using the additional drive unit.

A "favorable" operating point in the sense of the invention is when operating variables - in particular a torque and / or a rotational speed - of the internal combustion engine and / or operating variables of the exhaust gas aftertreatment system have values which have particularly low raw NOx emissions that are stable with respect to temporal fluctuations (upstream of the Nitrogen oxide-reducing catalyst) and / or a particularly low NOx content in the exhaust gas downstream of the catalyst and / or a particularly rapid reaching of an operating temperature of the catalyst, which is then as stable as possible over time, in the exhaust gas. Operating points with a load that is as constant as possible over time, which is preferably within a threshold value band specific for a drive device, can also be favorable operating points for diagnosis. These can be present, for example, when the vehicle is operated at a constant speed and / or load that is constant over time, in particular a load of 25% of the total output. In this case, at least at times, a compromise between the said operating parameters, which is selected according to predefinable criteria, can be a favorable operating point. It is known that a catalyst has only comparatively poor NOx conversion properties below a specific operating temperature. In the simplest case, the "favorable" operating point is defined by an operating parameter that is in a certain ratio to a defined limit.

In particular, according to the invention, the at least one further drive unit is used to change the operating point of the internal combustion engine, if necessary. For example, the internal combustion engine can be relieved by means of the additional drive unit if the drive unit is used in a supporting (motor) manner. So-called high-load operation, which generally represents an unfavorable (ie “not favorable”) operating point, can essentially be avoided. Likewise, depending on a particular embodiment of the further drive unit, the latter can optionally be operated such that the internal combustion engine is additionally loaded (generator operation). This also avoids so-called low-load operation of the internal combustion engine, which can also represent an unfavorable operating point.

In one embodiment of the method according to the invention, the range of the operating points of the internal combustion engine, which are defined as favorable for the diagnosis of exhaust gas aftertreatment, is defined by at least one map and corresponding limit values, the at least one map being determined by an effective mean pressure in a combustion chamber (cylinder) of the internal combustion engine and a speed the internal combustion engine or equivalent sizes is formed. The effective medium pressure essentially characterizes a torque of the internal combustion engine. For example, a map can be used to describe a three-dimensional relationship between the mean pressure, the speed and a NOx conversion in the catalytic converter. Likewise, a three-dimensional relationship between the mean pressure, the speed and a temperature of the catalytic converter and / or the exhaust gas can be described by means of the (or another) map. This brings essential operating variables of the internal combustion engine into a context that is particularly suitable for the method. Characteristic maps are particularly well suited for describing variables characterizing the internal combustion engine and the exhaust gas aftertreatment system.

• - Temperatur des Abgases;
• - Volumenstrom des Abgases;
• - Konzentration von Kohlenwasserstoffen (HC) im Abgas;
• - Konzentration von Stickoxiden im Abgas stromaufwärts des Abgasnachbehandlungssystems (NOx-Rohemissionen);
• - Konzentration von Stickoxiden im Abgas stromabwärts des Abgasnachbehandlungssystems;
• - Verhältnis von NO2 (Stickstoffdioxid) zu NOx (übrige Stickstoff-Sauerstoffverbindungen) im Abgas;
• - Enthalpie des Abgases;
• - Betriebszustand des Abgasnachbehandlungssystems;
• - Fahrerwunschmoment;
• - eingelegter Gang; und/oder
• - Ladezustand eines Energiespeichers;

Furthermore, the method according to the invention provides that at least one of the following input variables is taken into account when determining the operating point which is defined as favorable for the diagnosis of exhaust gas aftertreatment:

• - temperature of the exhaust gas;
• - volume flow of the exhaust gas;
• - concentration of hydrocarbons (HC) in the exhaust gas;
• - concentration of nitrogen oxides in the exhaust gas upstream of the exhaust gas aftertreatment system (raw NOx emissions);
• - concentration of nitrogen oxides in the exhaust gas downstream of the exhaust gas aftertreatment system;
• - ratio of NO2 (nitrogen dioxide) to NOx (other nitrogen-oxygen compounds) in the exhaust gas;
• - enthalpy of the exhaust gas;
• - operating state of the exhaust gas aftertreatment system;
• - driver request torque;
• - engaged gear; and or
• - State of charge of an energy store;

In addition to these variables, a quantity of a reducing agent introduced into the exhaust gas aftertreatment system and / or a quality of the mixing (“even distribution”) of the reducing agent in the exhaust gas can also determine the operating point defined as favorable. Furthermore, the operating point defined as favorable can depend on a particular embodiment of the internal combustion engine and / or the exhaust gas aftertreatment system, for example a respective catalyst technology. Taking into account at least one - preferably several - of the variables described here, the operating point defined as favorable can be advantageously determined, in particular with regard to the NOx conversion of the catalyst. This is preferably done using data stored in the map.

It is also provided that the internal combustion engine can be a diesel, gasoline and / or gas engine and that the exhaust gas aftertreatment system comprises an SCR catalytic converter (SCR means “selective catalytic reduction”). Diesel engines generally produce a particularly high proportion of NOx in relation to the raw exhaust gas emissions, and an SCR catalytic converter can reduce the nitrogen oxides in the exhaust gas particularly strongly. However, such a system can also be used advantageously in gasoline and / or gas engines in order to further reduce any NOx that may arise.

The method according to the invention can be carried out particularly effectively if the further drive unit is at least one electric motor. The electric motor can be switched on or off in a simple manner while the motor vehicle is in motion, and can also be switched over just as easily between motor operation and generator operation. In generator operation, a battery or another electrical energy storage device of the motor vehicle can preferably be charged, as a result of which the internal combustion engine is additionally loaded in a low-load operation as mentioned above and can thus be operated at a more favorable operating point.

It is further provided that the internal combustion engine is controlled and / or regulated in this way is that the torque and / or the speed of the internal combustion engine preferably have an approximately medium value. In the present case, a “mean” value of the torque is understood to mean that the torque is approximately between 20 percent and 50 percent of a maximum torque of the internal combustion engine. An “average” value of the speed is understood to mean that the speed is approximately between 20 percent and 80 percent of a maximum speed of the internal combustion engine. So if the torque and speed each have “medium” values, then both the operating temperature of the SCR catalytic converter can be optimized and the NOx conversion achieved in the exhaust gas aftertreatment system can be set particularly favorably for diagnosis.

Furthermore, it is provided that, using at least one of the input variables described above, a variable characterizing a driver's desired torque and / or a variable characterizing a load ratio of the internal combustion engine and the electric motor is ascertained, and that the ascertained quantity or the ascertained quantities is sent to a control and / or control device for the internal combustion engine and for the electric motor are transmitted. In this way, taking into account a current driver's desired torque, a current operating point of the internal combustion engine and the electric motor, and further variables, the operating point of the internal combustion engine using the electric motor can be brought into a range which is rated as favorable for exhaust gas aftertreatment by means of the control and / or regulating device.

In addition, it is provided that a lower and an upper limit value are specified in order to limit the driver's desired torque or a “torque request” of the control and / or regulating device determined therefrom. Depending on a particular driving situation, the driver's desired torque can thus be limited to a reasonable amount, if necessary.

One embodiment of the invention provides that the electric motor is operated as a generator with a comparatively low torque and / or low speed of the internal combustion engine in order to additionally load the internal combustion engine and thus bring it into the desired operating point range. Thus, the internal combustion engine can be operated in a more favorable range of torque and speed by means of “load application” and thus the NOx conversion in the catalytic converter can be increased. The electrical energy obtained is preferably used to charge a battery assigned to the electric motor.

Correspondingly, at a comparatively high torque and / or high speed of the internal combustion engine, the further drive unit or the electric motor can be operated as a motor in order to relieve the load on the internal combustion engine and thus bring it into the desired operating point range. “High load points” of the internal combustion engine with a NOx conversion in the catalytic converter which is favorable for diagnosis and preferably constant over time can thus be avoided by connecting the further drive unit. In this case, in the case of the electric motor, the energy previously stored in generator operation can advantageously be used for driving. Such measures can also be predicted using environmental data, traffic conditions, route profile, etc. For example, the connection of the electric motor makes it possible to avoid high NOx fractions during operation outside an applicable range of exhaust gas recirculation of the internal combustion engine. It is also possible according to the invention to switch off the internal combustion engine completely for a certain duration and to use the electric motor (s) as the sole drive in the drive device. However, this typically takes place outside of the diagnostic cycles.

In addition, it can also be provided that a need for a diagnosis of the exhaust gas aftertreatment system is ascertained, and in the event that a diagnosis need is ascertained, an energy store coupled to the drive unit is discharged to a lower threshold, the diagnosis only after the lower one has been reached Threshold is initiated. As a result, the memory has sufficient capacity to operate an electrical machine as a generator. A corresponding procedure can also be provided for a filled energy store and motor operation. This is particularly advantageous in connection with the use of environmental data, traffic situation, route profile, etc., since the motor or generator operation can be coordinated advantageously in terms of time and energy.

The method according to the invention is particularly simple and reliable to carry out if it is carried out using stored data and / or at least one map and / or at least one mathematical operation. This takes place, for example, in the control and / or regulating device, which in particular comprises a computer program that is programmed to operate the drive device in the manner according to the invention.

• 1 eine Antriebseinrichtung eines Kraftfahrzeugs mit einer Brennkraftmaschine, einem Getriebe, einem Abgasnachbehandlungssystem und einem Elektromotor;
• 2 ein Diagramm mit einem NOx-Umsatz über einer Drehzahl und einem effektiven Mitteldruck;
• 3 ein Diagramm mit einer Temperatur eines SCR-Katalysators über der Drehzahl und dem effektiven Mitteldruck; und
• 4 ein Flussdiagramm zur Durchführung eines Verfahrens zum Betreiben der Antriebseinrichtung.

Exemplary embodiments of the invention are explained below with reference to the drawing. The drawing shows:

• 1 a drive device of a motor vehicle with an internal combustion engine, a transmission, an exhaust gas aftertreatment system and an electric motor;
• 2nd a diagram with a NOx conversion over a speed and an effective medium pressure;
• 3rd a diagram with a temperature of an SCR catalyst over the speed and the effective medium pressure; and
• 4th a flowchart for performing a method for operating the drive device.

The same reference numerals are used for functionally equivalent elements and sizes in all figures, even in different embodiments.

1 shows a drive device 10th a motor vehicle not shown. In an upper left area in the drawing is an internal combustion engine 12 symbolically represented, which over an exhaust pipe 14 Exhaust gas in an exhaust gas aftertreatment system 16 can flow in. The internal combustion engine is present 12 designed as a diesel engine. The exhaust aftertreatment system 16 is shown in a lower area in the drawing and in the drawing the exhaust gas flows essentially from left to right. The exhaust aftertreatment system 16 has a diesel oxidation catalyst in the direction of flow of the exhaust gas 18th , a diesel particulate filter 20th , a feed device 22 for an aqueous urea solution 24th , and an SCR catalyst 26 on (SCR means "selective catalytic reduction"). In an area on the left in the middle of the drawing are an electric motor 28 as well as a transmission 30th arranged. The electric motor 28 can be through an electrical wire 32 with a battery 34 exchange electrical energy. The gear 30th is about a wave 36 with the internal combustion engine 12 coupled, and over a shaft 38 with the electric motor 28 coupled. In the drawing on the left of the gearbox 30th are drive wheels 40a and 40b of the motor vehicle, each drawn over a shaft 42a and 42b with the gear 30th are coupled.

The exhaust aftertreatment system 16 the internal combustion engine 12 also includes a lambda probe 62 upstream of the diesel oxidation catalyst 18th , and one NOx sensor each 64 upstream and downstream of the SCR catalyst 26 . The exhaust aftertreatment system also includes 16 in addition four temperature sensors 66 which are located at various points in the exhaust gas aftertreatment system 16 are arranged. Furthermore, the urea solution 24th in a container 68 arranged, which via a hydraulic line 70 with the feed device 22 connected is.

In an upper middle area of the drawing is a control and / or regulating device 44 arranged which is a computer program 46 and a data store 48 includes. The data store 48 includes at least one map 49 . The control and / or regulating device 44 is about electrical wiring 50 and 52 with components of the internal combustion engine 12 connected and via electrical lines 54 and 56 with components of the exhaust gas aftertreatment system 16 .

Furthermore, the control and / or regulating device 44 with electrical wires 58 with the electric motor 28 connected, as well as via electrical lines 60 with the battery 34 . The electrical lines 50 , 52 , 54 , 56 , 58 and 60 each characterize a possible plurality of individual electrical connections which are in the 1 are not shown separately. Furthermore, signals from an accelerator pedal 57 , a brake pedal 59 and a clutch pedal 61 to the control and / or regulating device 44 transmitted. From an accelerator pedal position 57 , if necessary additionally of the brake pedal 59 and the clutch pedal 61 as well as from one in the gearbox 30th The gear engaged can be a variable that characterizes a driver's desired torque 63 be determined.

Likewise, a load ratio of the internal combustion engine 12 and the electric motor 28 characteristic size 120 (see the 4th ) be determined. The load ratio can be defined, for example, as the quotient of the current mechanical power of the electric motor 28 to a current mechanical performance of the internal combustion engine 12 , which in total cause the drive of the motor vehicle. In the present case, the control and / or regulating device leads 44 both determining the sizes 63 and 120 as well as the control or regulation of the internal combustion engine 12 and the electric motor 28 by. However, it is also possible to use the sizes 63 and 120 to be determined in a structurally separate unit and then to the control and / or regulating device 44 to transmit.

In operation of the drive device 10th , or the associated motor vehicle, controls the control and / or regulating device 44 the internal combustion engine 12 , the electric motor 28 and the exhaust aftertreatment system 16 . For this, the control and / or regulating device evaluates 44 current positions of the accelerator pedal 57 , the brake pedal 59 , the clutch pedal 61 as well as a variety of other operating states and / or signals. This applies in particular to the internal combustion engine 12 or that in the internal combustion engine 12 installed components, the electric motor 28 , the battery 34 , The gear 30th , the drive wheels 40a and 40b and signals from the sensors of the exhaust gas aftertreatment system described above 16 . Furthermore, the tax and / or control device 44 reading and writing to the data storage 48 access, using the stored data and / or the map 49 and / or mathematical operations of the internal combustion engine 12 , the electric motor 28 and the exhaust aftertreatment system 16 controls and / or regulates.

2nd shows a first diagram to illustrate operating states of the internal combustion engine 12 . There is a speed on the abscissa of the coordinate system shown 78 the internal combustion engine 12 applied. There is an effective medium pressure on the associated ordinate 80 in a combustion chamber of the cylinders of the internal combustion engine 12 applied. The effective medium pressure 80 characterizes a torque of the internal combustion engine 12 . The third quantity in the coordinate system is 2nd a NOx turnover 82 entered, areas in the drawing characterized by different types of graphic pattern corresponding value ranges of the NOx conversion 82 represent. An assignment of the values of the NOx conversion 82 to the graphic patterns is through a scale of values 84 in the right area of 2nd shown. The scale of values 84 is with value ranges 81 , 83 , 85 , 87 and 89 dimensioned between zero and one, with a value of zero representing poor NOx conversion 82 and a value of one means particularly good NOx conversion 82 in the SCR catalyst 26 characterized. The values of the present diagram can, for example, in the map 49 be saved.

It can be seen that there is a "favorable" area in an approximately middle area of the diagram, which essentially corresponds to the value area 89 corresponds. In the range of values 89 can have a good to maximum NOx conversion 82 with values between approximately 0.8 and 1. The NOx conversion is in an upper area of the diagram 82 in a range of approximately 0.1 to 0.4 and can therefore be described as unfavorable. Individual areas 91 have good values up to approximately one, but these areas are 91 comparatively small. The NOx conversion is in a lower area of the diagram 82 again unfavorable. The said “medium” range comprises values of the effective medium pressure 80 approximately between 20 percent and 50 percent of a maximum effective mean pressure 80 the internal combustion engine 12 , and values of the speed 78 approximately between 20 percent and 80 percent of a maximum speed 78 the internal combustion engine 12 .

The 2nd shows that there is an area for particularly good NOx sales 82 in the SCR catalyst 26 in a medium load range of the internal combustion engine 12 lies. At comparatively high and comparatively low loads (corresponding to a respective speed 78 and / or a respective torque of the internal combustion engine 12 ) is the NOx turnover 82 relatively inconvenient. Using the in the 2nd shown diagram or the map 49 as well as a number of other information (see the 1 ) can control or regulate the drive device 10th done optimized. In particular, the internal combustion engine 12 controlled and / or regulated such that the torque and / or the speed 78 preferably have an approximately medium value. Among other things, the electric motor 28 Enabled degrees of freedom (hybrid drive) exploited to both the efficiency of the drive device 10th as well as the exhaust gas composition - especially the NOx conversion 82 - to optimize. The control and / or regulating device 44 takes over the function of a "SCR operating point coordinator", so to speak.

Furthermore, the control and / or regulating device 44 with a cold start of the internal combustion engine 12 a rapid reaching of a minimum operating temperature of the SCR catalytic converter 26 enable, while thanks to the diagram operating states of the internal combustion engine 12 can be preferred, which thereby an optimized NOx conversion 82 enable. Further parameters, such as an exhaust gas enthalpy (catalyst heating) and a proportion of so-called NOx raw emissions, can be taken from the control and / or regulating device 44 also determined and for the control of the drive device 10th be used accordingly.

Additional signals from the exhaust aftertreatment system are added 16 considered. For example, signals from the lambda sensor 62 , the NOx sensors 64 and the temperature sensors 66 . Furthermore, a regeneration operation of the diesel particle filter 20th , as well as a state of charge of the battery 34 determined and for the operation of the drive device 10th considered. Furthermore, the control and / or regulating device 44 trained to different "priorities", that is, certain rankings of different, the drive device 10th determining sizes to be taken into account. For example, the control and / or regulating device 44 prioritize a driver's desired torque if necessary higher than the requirements of an efficiency of the drive device 10th .

The function of the "SCR operating point coordinator" is therefore, taking into account various variables relevant to NOx sales, the most favorable and, so to speak, "ideal" operating point of the internal combustion engine 12 adjust. Boundary conditions, such as the driver's desired torque, and / or a possible regeneration of the diesel particle filter are thereby considered 20th and / or a state of charge of the battery 34 with used. The "SCR operating point coordinator" can, if necessary, derive a current "torque request" determine which in the control and / or regulating device 44 to control the drive device 10th is used. As described above, certain ranking sequences are also taken into account, in particular in relation to the driver's desired torque specified by the driver. The benefit of the "SCR operating point coordinator" generally increases with an increasing relative power of the electric motor 28 in relation to the internal combustion engine 12 to.

3rd shows one to the 2nd Similar coordinate system in which the speed on the abscissa 78 the internal combustion engine 12 and the effective medium pressure on the ordinate 80 are applied. Unlike that 2nd is in the 3rd the third variable is a temperature 90 in the SCR catalyst 26 registered. The diagram of the 3rd has areas 92 , 94 , 96 , 98 and 100 on what different temperature ranges of the SCR catalyst 26 characterize. For this purpose, the drawing has numbers shown in small rectangular fields, which represent a respective temperature of the SCR catalytic converter 26 in degrees Celsius.

The area 92 shows temperatures of the SCR catalyst 26 which for optimal NOx conversion 82 are too hot. The surface shows accordingly 100 a temperature range, which for an optimal NOx conversion 82 is too cold. Arrows 102 indicate a respective preferred direction in the diagram, which results in sufficient or good or very good NOx conversion 82 in the operation of the drive device 10th can be achieved. Optimal areas for a diagnosis D are in particular areas with an optimal NOx conversion 82 .

4th shows a flowchart for performing a method for operating the drive device 10th , in which a diagnosis of the exhaust gas aftertreatment system 16 is carried out. For example, the flowchart may be from the computer program 46 be processed. In a starting block 104 begins in the 4th procedure shown.

• - Temperatur des Abgases;
• - Volumenstrom des Abgases;
• - Konzentration von Kohlenwasserstoffen im Abgas;
• - Konzentration von Stickoxiden im Abgas stromaufwärts des Abgasnachbehandlungssystems 16;
• - Konzentration von Stickoxiden im Abgas stromabwärts des Abgasnachbehandlungssystems 16;
• - Verhältnis von NO2 (Stickstoffdioxid) zu NOx (übrige Stickoxide) im Abgas;
• - Enthalpie des Abgases;
• - Betriebszustand des Abgasnachbehandlungssystems 16;
• - Fahrerwunschmoment, welches aus der Position des Gaspedal 57, des Bremspedals 59, des Kupplungspedals 61 und eines eingelegten Gangs ermittelt wird; und/oder
• - Ladezustand der Batterie 34 bzw. eines sonstigen Energiespeichers.

In a subsequent block 106 becomes an operating state of the drive device 10th and the exhaust gas aftertreatment system 16 determined. For example, for the determination of the operating point of the drive device which is assessed as “favorable” for a diagnosis D. 10th , in particular the internal combustion engine 12 and the electric motor 28 , the following variables or parameters are taken into account as input variables:

• - temperature of the exhaust gas;
• - volume flow of the exhaust gas;
• - concentration of hydrocarbons in the exhaust gas;
• - concentration of nitrogen oxides in the exhaust gas upstream of the exhaust gas aftertreatment system 16 ;
• - Concentration of nitrogen oxides in the exhaust gas downstream of the exhaust gas aftertreatment system 16 ;
• - ratio of NO2 (nitrogen dioxide) to NOx (other nitrogen oxides) in the exhaust gas;
• - enthalpy of the exhaust gas;
• - Operating state of the exhaust gas aftertreatment system 16 ;
• - Driver request torque, which is from the position of the accelerator pedal 57 , the brake pedal 59 , the clutch pedal 61 and an engaged gear is determined; and or
• - Battery charge level 34 or other energy storage.

Preferably in the block 106 also lower and upper limit values 105 and 107 Specified in order to limit a “torque request” determined from the driver's desired torque and / or to adapt it to a value that is favorable for diagnosis, within a threshold value band defined by the predefined threshold values.

A "favorable" operating point D of the drive device 10th it is when these input variables have values which, in their entirety, have low and stable NOx raw emissions in the exhaust pipe 14 and / or a low and stable NOx component in the exhaust gas downstream of the SCR catalytic converter 26 and / or a particularly rapid and then stable over time the fluctuations in the operating temperature of the SCR catalytic converter 26 enable. Also operating points with a load that is as constant as possible over time, preferably within one for a drive device 10th specific threshold band 105 ; 107 lies, can be favorable operating points for a diagnosis. These can be present, for example, when the vehicle is operated at a constant speed and / or constant load, in particular a load of 25% of the total power. In this case, at least at times, a compromise of the said input variables selected according to predefinable criteria can also be a favorable operating point D for a diagnosis.

In a query block 108 it is determined whether an operating area of the exhaust gas aftertreatment system 16 has a favorable operating state D for diagnosis. In particular, the internal combustion engine 12 generated raw NOx emissions, a temperature of the SCR catalyst 26 and a volume flow of the exhaust gas in the exhaust gas aftertreatment system 16 determined, for example by comparing with corresponding limit values. If the operating range enables an at least approximately “optimal” operating point, a diagnosis is made 109 carried out and after successful diagnosis the procedure in step 122 completed. If the diagnosis was unsuccessful, the block can be input 106 be branched back.

Otherwise, in a subsequent block 110 queried whether the temperature of the exhaust gas aftertreatment system 16 , especially the SCR catalytic converter 26 , lies above one for the suitable range D, and / or whether the volume flow of the exhaust gas is possibly too high, and / or whether that of the internal combustion engine 12 generated raw NOx emissions are too high. If so, it becomes a following block 112 branches.

If this is not the case, another query block will be used 114 queried whether the temperature of the exhaust gas aftertreatment system 16 may be too low for a suitable area D for diagnosis. If the temperature is not too low, the diagnostic block is sent to the input 109 branched and the diagnosis carried out. Otherwise, the query block 114 to a subsequent block 116 branches.

In the block 112 is stored using data in the data storage 48 stored map 49 the torque and / or the speed 78 the internal combustion engine 12 shifted towards lower values to the internal combustion engine 12 thus to relieve. After that, the procedure is in one block 118 continued.

In the block 116 is stored using data in the data storage 48 stored map 49 the torque and / or the speed 78 the internal combustion engine 12 shifted towards higher values to the internal combustion engine 12 thus burden more. Then the procedure is also in the block 118 continued.

In the block 118 will be in the blocks earlier 112 and 116 Planned change in torque and / or speed 78 prioritize. For example, a current driver's desired torque can preferably be taken into account. In addition, a load ratio of the internal combustion engine 12 and the electric motor 28 characteristic size 120 determined. Then by means of a computer program 46 realized “hybrid coordinator” function, which can take over the data or quantities required from the “SCR operating point coordinator”, an operating state of the drive device 10th changed if necessary.

For example, with a comparatively low torque and / or low speed 78 the internal combustion engine 12 the electric motor 28 operated as a generator to the internal combustion engine 12 in addition to the power required for the current driving operation of the motor vehicle and thus to bring them into the desired operating point range D for diagnosis. If this desired operating point is reached, the diagnosis is carried out 109 carried out. In a subsequent end block 122 ends in the 4th illustrated diagnostic procedure.

If the diagnosis was unsuccessful, the block can be input 106 be branched back. Accordingly, at a comparatively high torque and / or high speed 78 the internal combustion engine 12 the electric motor 28 operated as a motor to the internal combustion engine 12 to relieve and thus bring them into the desired operating point range D. If this desired operating point is reached, the diagnosis is carried out 109 carried out. In a subsequent end block 122 ends in the 4th illustrated diagnostic procedure. If the diagnosis was unsuccessful, the block can be input 106 be branched back. The motor or generator loading of the electric motor 28 can also be carried out predictively depending on the state of charge of a battery or depending on the expected route profile, inclines or the traffic situation. The state of charge as such can also be carried out predictively as a function of the expected route profile, inclines or the traffic situation.

In particular, by means of the 4th procedure illustrated using the drive device 10th predetermined "degrees of freedom" the operating point of the internal combustion engine 12 optimized so that an optimal diagnosis can be carried out. NOx conversion is also particularly preferred 82 of the exhaust gas aftertreatment system 16 maximized. For example, the internal combustion engine 12 are controlled and / or regulated such that the torque and / or the speed 78 preferably have an approximately medium value. A “temperature profile” of the SCR catalytic converter can also be used 26 or the exhaust gas aftertreatment system 16 and / or a “raw NOx emission profile” of the internal combustion engine 12 efficiency can be realized.

Claims (11)

Method for operating a drive device (10), in particular in a motor vehicle, comprising an internal combustion engine (12) and at least one further drive unit (28) which is not an internal combustion engine (12), with an exhaust gas from the Internal combustion engine (12) is treated by means of an exhaust gas aftertreatment system (16), characterized in that it is checked whether the internal combustion engine (12) is in an operating point which is defined as favorable for a diagnosis of the exhaust gas aftertreatment, and when it is determined that the internal combustion engine (12) is not located in an operating point that is defined as favorable for the diagnosis of exhaust gas aftertreatment, the operating point of the internal combustion engine (12) is brought into an area defined as favorable for exhaust gas aftertreatment using the additional drive unit (28). Procedure according to Claim 1 , characterized in that the range of the operating points of the internal combustion engine (12) which are defined as favorable for the diagnosis of exhaust gas aftertreatment is defined by at least one map (49) and corresponding limit values, which map (49) by an effective mean pressure (80) and a speed (78) or equivalent sizes is formed. Method according to one of the preceding claims, characterized in that at least one of the following input variables is taken into account when determining the operating point which is defined as favorable for the diagnosis of exhaust gas aftertreatment: - temperature of the exhaust gas; - volume flow of the exhaust gas; - concentration of hydrocarbons in the exhaust gas; - Concentration of nitrogen oxides in the exhaust gas upstream of the exhaust gas aftertreatment system (16); - concentration of nitrogen oxides in the exhaust gas downstream of the exhaust gas aftertreatment system (16); - ratio of NO2 to NOx in the exhaust gas; - enthalpy of the exhaust gas; - Operating state of the exhaust gas aftertreatment system (16); - driver request torque; - engaged gear; and / or - state of charge of an energy store (34); Method according to one of the preceding claims, characterized in that the exhaust gas aftertreatment system (16) comprises an SCR catalytic converter (26) and in that the further drive unit (28) is an electric motor (28) which can be operated as a generator and / or motor. Method according to one of the preceding claims, characterized in that, using at least one of the input variables, a variable (63) characterizing a driver's desired torque and / or a variable (120) characterizing a load ratio of the internal combustion engine (12) and the drive unit (28) is determined , and that the determined size (63, 120) or the determined sizes (63, 120) are transmitted to a control and / or regulating device (44) for the internal combustion engine (12) and for the drive unit (28). Method according to one of the preceding claims, characterized in that the drive unit (28) is controlled in a generator manner in order to additionally load the internal combustion engine (12) and thus bring it to an operating point which is favorable for diagnosis of the exhaust gas aftertreatment system (16) and / or that the drive unit (28) is controlled by a motor in order to relieve the load on the internal combustion engine (12) and thus bring it to an operating point which is favorable for diagnosis of the exhaust gas aftertreatment system (16). Method according to one of the preceding claims, characterized in that a need for a diagnosis of the exhaust gas aftertreatment system (16) is determined, and in the event that a diagnosis need is determined, an energy store (34) coupled to the drive unit (28) up to one the lower threshold is discharged, the diagnosis being initiated only after the lower threshold value has been reached. Method according to one of the preceding claims, characterized in that activation of the drive unit (28) is predicted for at least one external condition for determining a diagnostic interval, in particular a route profile or an expected traffic situation. Computer program for a control and / or regulating device (44) of a motor vehicle, characterized in that it is programmed to implement a method according to one of the Claims 1 to 8th perform. Machine-readable storage medium on which a computer program according to the preceding claim is stored. Control and / or regulating device (44) for a motor vehicle, characterized in that it is set up to carry out a method according to one of the preceding claims.

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