DE102020103899A1 - Method for operating an internal combustion engine and control unit - Google Patents

Abstract

The invention relates to a method for operating an internal combustion engine (10) which is connected to a control unit (80) in which several control subprograms (Sn) for operating the internal combustion engine (10) are stored A control subprogram (Ssel) is selected from the control subprograms (Sn) stored in the control unit (80), with which the current legal framework conditions and possibly other target variables are complied with. It is provided that in the case of a plurality of control sub-programs (Sn) possible to meet the legal framework conditions, the control sub-program (Ssel) which causes the lowest operating costs is selected. The invention also relates to a control unit (80) for carrying out such a method, wherein the The control device (80) has a memory (90) and a computing unit (92), a machine-readable program code (94) being stored in the memory (90), and the machine-readable program code (94) being executed by the computing unit (92). carries out such a procedure.

Description

The invention relates to a method for operating an internal combustion engine and a control device for carrying out such a method according to the preamble of the independent claims.

The current exhaust gas legislation, and one that will become increasingly strict in the future, place high demands on the engine-related raw emissions and the exhaust gas aftertreatment of internal combustion engines. The demands for a further decrease in consumption and the further tightening of the exhaust gas standards with regard to the permissible nitrogen oxide emissions represent a challenge for the engine developers. Exhaust aftertreatment systems are currently used in diesel engines, which use an oxidation catalytic converter, a catalytic converter for the selective catalytic reduction of nitrogen oxides (SCR catalytic converter). as well as a particle filter for separating soot particles and optionally further catalysts, in particular a NO _x storage catalyst. Ammonia is preferably used as the reducing agent for the SCR catalytic converter. Because dealing with pure ammonia is complex, a synthetic, aqueous urea solution is usually used in vehicles, which is mixed with the hot exhaust gas flow in a mixing device upstream of the SCR catalytic converter. As a result of this mixing, the aqueous urea solution is heated, the aqueous urea solution releasing ammonia in the exhaust gas duct. A commercially available, aqueous urea solution generally consists of 32.5% urea and 67.5% water.

In order to optimally adjust the internal combustion engine to the respective operating situation, different operating modes are stored in the control unit. The operating mode coordinator selects that operating mode as a function of a defined driving cycle which is considered to be optimal in this driving cycle with regard to emissions, driving comfort, performance or other target values.

From the DE 10 2016 112 610 B4 a method for operating an internal combustion engine is known, the internal combustion engine having at least one control device, at least one exhaust gas aftertreatment device and at least one exhaust gas recirculation device, which comprises the following steps: providing at least one operating parameter of the internal combustion engine to an input interface; Determining the current and / or long-term emission and / or consumption values from the operating parameters provided in a data collection block; Determining at least one target value of an internal combustion engine parameter on the basis of the values from the data collection block in a target value definition block; Prioritizing the determined target values taking into account the determined emission and / or consumption values in a prioritization block; Determining at least one internal combustion engine manipulated variable based on the deviation between the values and the emission and / or consumption values estimated by the target values according to the prioritization in a comparison block and transferring at least one internal combustion engine manipulated variable to an output interface.

A disadvantage of this method, however, is that it requires a high level of computing power. In addition, a fixed assignment of each operating point in a characteristic map to a respective control subroutine means that increased fuel consumption may be accepted, although this would not be necessary due to a change in the operating mode.

The invention is now based on the object of selecting the most cost-effective operating mode from the operating modes stored in the control unit with comparatively little effort, which meets the legal framework requirements, in particular the requirements for exhaust gas or noise emissions.

According to the invention, this object is achieved by a method for operating an internal combustion engine which is connected to a control device in which several control sub-programs for operating the internal combustion engine are stored. An operating mode coordinator selects a control subprogram from the control subprograms stored in the control device, with which the current legal framework conditions and, if necessary, other target variables are complied with. According to the invention, it is provided that in the case of a plurality of control sub-programs that are possible to meet the legal framework conditions, the control sub-program which causes the lowest operating costs is selected. For each operating mode of the internal combustion engine, a control sub-program is stored in the control unit of the internal combustion engine, so that the corresponding control sub-program can be executed as a function of the selected operating mode. The operating mode coordinator is stored as a software function in the control unit of the internal combustion engine. This can reduce the operating costs for the driver.

The further features listed in the dependent claims allow advantageous further developments and improvements of the method for operating an internal combustion engine specified in the independent claim.

In a preferred embodiment of the invention, it is provided that the corresponding subprogram is selected which has the lowest fuel consumption at this operating point of the internal combustion engine. By selecting the control sub-program with the lowest fuel consumption, the carbon dioxide emissions of the motor vehicle can be reduced.

In a further preferred embodiment of the invention it is provided that the corresponding control subprogram is selected which has the lowest consumption of auxiliary resources, in particular the lowest consumption of aqueous urea solution for the selective, catalytic reduction of nitrogen oxides, at this operating point of the internal combustion engine. This means that it is necessary to refill with aqueous urea solution less frequently.

In an advantageous embodiment of the method it is provided that the selection of the corresponding control subprogram by the operating mode coordinator is used for exhaust gas temperature management of the internal combustion engine. Exhaust gas temperature management can ensure that the exhaust gas aftertreatment components are always operated in a temperature range in which a maximum conversion of the pollutants contained in the exhaust gas flow of the internal combustion engine takes place. In particular, an SCR catalytic converter and / or a particle filter with a coating for the selective, catalytic reduction of nitrogen oxides can be kept in an operating temperature range in which a particularly efficient conversion of the nitrogen oxide emissions of the internal combustion engine is possible.

In a further improvement of the method it is provided that a cost function is stored in the control unit of the internal combustion engine for each control sub-program. A cost function enables different control sub-programs to be quantitatively compared with one another, so that the most cost-effective control sub-program can be selected for each driving situation.

It is particularly preferred if the cost function includes activation costs for activating the control sub-program and operating costs for executing the control sub-program. Different operating modes and thus the execution of different control subprograms lead to different operating costs. The activation of an operating mode can lead to additional costs, which differ greatly from the costs of the further implementation of the operating mode. Thus, these activation costs should be taken into account in addition to the operating costs when performing the respective operating mode. A further improvement of the operating mode coordinator is thus possible.

In a preferred embodiment of the method it is provided that the control sub-program with the lowest operating costs is selected on the basis of a prediction of the duration of activity of the selected control sub-program. If, on the basis of predictive data, it can be predicted how the internal combustion engine is likely to be operated in the upcoming operating phase, the corresponding control sub-programs can be selected in advance and coordinated accordingly in the process in such a way that the maximum efficiency of the internal combustion engine is achieved. As a result, the operating costs and, in particular, the fuel consumption can be reduced.

It is particularly preferred if the selection of the control sub-program is determined on the basis of statistics from driving cycles and / or driving situations carried out by the driver. If the driving habits of the driver are known, the suitable operating modes and thus the corresponding subprograms can be selected on the basis of the route likely to be covered and / or the likely expected power demand on the internal combustion engine in order to minimize the operating costs of the internal combustion engine.

In an advantageous further development of the method, it is provided that a calculation of the operating parameters using a model of the driving situation and the resulting courses of the operating parameters and / or an estimation from predictive route data for the planned route takes place. If a planned route has been determined by the navigation system, it can be determined on the basis of the general conditions to be expected, for example the selected roads, the topography and the traffic density, when which operating mode is particularly advantageous. For example, a regeneration of the particle filter can be planned during a longer high-load phase so that additional heating measures for heating the particle filter to its regeneration temperature can be omitted or at least severely restricted.

Another aspect of the invention relates to a control device for performing such a method, the control device having a memory and a computing unit, a machine-readable program code being stored in the memory, and the machine-readable program code executing such a method when executed by the computing unit.

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

• 1 eine schematische Darstellung eines Verbrennungsmotors zur Durchführung eines erfindungsgemäßen Verfahrens zum Betreiben eines Verbrennungsmotors;
• 2 ein Kraftfahrzeug mit einem Verbrennungsmotor sowie einem Steuergerät, welches dazu eingerichtet ist, ein erfindungsgemäßes Verfahren zum Betreiben eines Verbrennungsmotors durchzuführen;
• 3 ein Ablaufdiagramm zur Auswahl des kostenoptimalen Steuerungsteilprogramms durch den Betriebsartenkoordinator;
• 4 ein Bewertungsschema zur Auswahl des kostenoptimalen Steuerungsteilprogramms;
• 5 eine Kostenfunktion beim Betrieb des Verbrennungsmotors in Abhängigkeit von dem ausgewählten Steuerungsteilprogramm; und
• 6 ein weiteres Ablaufdiagramm zur Auswahl einer kostenoptimalen Betriebsart des Verbrennungsmotors und des dazugehörigen Steuerungsteilprogramms durch den Betriebsartenkoordinator.

The invention is explained below in exemplary embodiments with reference to the accompanying drawings. Show it:

• 1 a schematic representation of an internal combustion engine for performing a method according to the invention for operating an internal combustion engine;
• 2 a motor vehicle with an internal combustion engine and a control device which is set up to carry out a method according to the invention for operating an internal combustion engine;
• 3 a flowchart for the selection of the most cost-effective control subprogram by the operating mode coordinator;
• 4th an evaluation scheme for selecting the most cost-effective control sub-program;
• 5 a cost function in the operation of the internal combustion engine as a function of the selected control subroutine; and
• 6th a further flow chart for the selection of a cost-optimal operating mode of the internal combustion engine and the associated control subprogram by the operating mode coordinator.

1 shows the schematic representation of an internal combustion engine 10 with an air supply system 20th and an exhaust system 40 . The internal combustion engine 10 is in this embodiment a direct injection diesel engine and has several combustion chambers 12th on. At the combustion chambers 12th is a fuel injector each 14th for injecting a fuel into the respective combustion chamber 12th arranged. The internal combustion engine 10 is with his inlet 16 with an air supply system 20th and with its outlet 18th with an exhaust system 40 tied together. The internal combustion engine 10 further comprises a high pressure exhaust gas recirculation 34 with an exhaust gas recirculation duct 36 and a high pressure EGR valve 38 , via which an exhaust gas from the internal combustion engine 10 from the outlet 18th to the inlet 16 can be traced back. At the combustion chambers 12th inlet valves and outlet valves are arranged, with which a fluidic connection from the air supply system 20th to the combustion chambers 12th or from the combustion chambers 12th to the exhaust system 40 can be opened or closed.

The air supply system 20th includes an intake duct 28 , in which in the direction of flow of fresh air through the intake duct 28 an air filter 22nd , downstream of the air filter 22nd an air mass meter 24 , in particular a hot film air mass meter, downstream of the air mass meter 24 a compressor 26th of an exhaust gas turbocharger 60 , downstream of the compressor 26th a throttle 30th and further downstream an intercooler 32 are arranged. The air mass meter can do this 24 also in a filter housing of the air filter 22nd be arranged so that the air filter 22nd and the air mass meter 24 forms an assembly. Downstream of the air filter 22nd and upstream of the compressor 26th a junction is provided at which an exhaust gas recirculation line 76 a low pressure exhaust gas recirculation 70 in the intake duct 28 flows out.

The exhaust system 40 includes an exhaust duct 42 , in which in the flow direction of an exhaust gas of the internal combustion engine 10 through the first exhaust duct 42 a turbine 44 of the exhaust gas turbocharger 60 is arranged, which the compressor 26th in the air supply system 20th drives over a shaft. The exhaust gas turbocharger 60 is preferably used as an exhaust gas turbocharger 36 designed with variable turbine geometry. To do this are a turbine wheel of the turbine 44 adjustable guide vanes are connected upstream, via which the flow of the exhaust gas onto the blades of the turbine 44 can be varied. Downstream of the turbine 44 are several exhaust aftertreatment components 46 , 48 , 52 , 56 , 58 intended. This is immediately downstream of the turbine 44 the first component of exhaust gas aftertreatment is an oxidation catalytic converter 46 or a NOx storage catalytic converter 82 is arranged. The oxidation catalyst 46 or the NOx storage catalytic converter 82 follows in the flow direction of the exhaust gas of the internal combustion engine 10 a particulate filter 48 , which is preferably with a coating 52 is provided for the selective catalytic reduction of nitrogen oxides (SCR coating). Downstream of the particulate filter 48 are an SCR catalytic converter 56 and further downstream, an ammonia barrier catalyst 58 provided, which prevents the escape of unused ammonia and converts the unused ammonia into molecular nitrogen and water vapor.

Downstream of the particulate filter 48 and upstream of the first SCR catalyst 56 is in the exhaust duct 42 an exhaust flap 78 provided with which the cross section of the exhaust duct 42 can be at least partially blocked to reduce the exhaust gas back pressure in the exhaust gas duct 42 to increase. Downstream of the particulate filter 48 and upstream of the exhaust flap 78 is on the exhaust duct 42 a branch 68 provided on which an exhaust gas recirculation line 76 an exhaust gas recirculation 70 from the exhaust duct 42 branches off.

The exhaust gas recirculation 70 includes in addition to the exhaust gas recirculation line 76 an exhaust gas recirculation cooler 72 and an exhaust gas recirculation valve 74 , via which the exhaust gas recirculation through the exhaust gas recirculation line 76 is controllable. On the exhaust gas recirculation line 76 the exhaust gas recirculation 70 A temperature sensor can be provided via which an exhaust gas temperature in the exhaust gas recirculation 70 can be determined to the exhaust gas recirculation 70 to activate as soon as the exhaust gas temperature in the exhaust gas recirculation 70 has exceeded a defined threshold. It can thus be prevented that water vapor or reducing agent contained in the exhaust gas for the selective catalytic reduction of nitrogen oxides, in particular liquid urea solution, condenses out and in the exhaust gas recirculation 70 or in the air supply system 20th leads to damage or deposits.

In the exhaust system 40 is downstream of the first SCR catalyst 56 and upstream of the second SCR catalyst 58 a combination sensor 64 provided, with which the nitrogen oxide concentration and the ammonia concentration downstream of the first SCR catalyst 56 can be determined. A temperature sensor can also be installed in the exhaust system 62 be provided with which an exhaust gas temperature in the exhaust system 40 can be monitored to ensure effective and efficient exhaust gas aftertreatment of the exhaust gas of the internal combustion engine 10 to enable. There are also differential pressure sensors 66 provided to create a pressure difference across the particulate filter 48 to determine. In this way, the loading status of the particle filter 48 and a regeneration of the particle filter when a defined load level is exceeded 48 be initiated. It is also on the exhaust duct 42 at least one metering module 50, 54 is provided to add a reducing agent, in particular aqueous urea solution, upstream of the two SCR catalytic converters 52 , 56 in the exhaust duct 42 to be dosed. There is a first metering valve 54 provided, which is downstream of the junction 68 and upstream of the SCR catalyst 56 Reducing agent, in particular aqueous urea solution, into the exhaust duct 42 dosed. There is also another metering valve 50 provided with which the reducing agent downstream of the oxidation catalyst 46 or of the NOx storage catalytic converter 82 and upstream of the particulate filter 48 in the exhaust duct 42 is introduced. In the exhaust duct 42 can each downstream of the respective metering valve 50 , 54 Mixing elements can be arranged to allow the reducing agent to be mixed with the exhaust gas of the internal combustion engine 10 to favor.

The internal combustion engine 10 is with an engine control unit 80 connected, which via signal lines, not shown, with the combination sensor 64 , the pressure and temperature sensors 62 , 66 , with the fuel injectors 14th of the internal combustion engine 10 as well as with the control devices 24 , 30th of the air supply system 20th connected is. The engine control unit 80 has at least one memory 90 and at least one processing unit 92 on. In the memory 90 is a program code 94 to control the internal combustion engine 10 filed. The program code 94 comprises several control sub-programs (S ₁ , S ₂ , S ₃ , ..., S _n ) for performing different operating modes of the internal combustion engine 10 . It is also on the engine control unit 80 an operating mode coordinator 88 which is the most cost-effective operating mode of the internal combustion engine to meet the legal framework conditions and other target achievement 10 and selects the associated control subprogram S _sel.

In 2 is a motor vehicle 100 with an internal combustion engine 10 shown. Here is the internal combustion engine 10 with its outlet 18th with an exhaust system 40 connected, which preferably as in 1 is carried out as described. The exhaust system 40 comprises several exhaust aftertreatment components 46 , 48 , 56 , 58 . The car 100 also has a navigation device 84 with which a route to a specific destination can be calculated. Furthermore, the motor vehicle 100 a data transfer system 86 , in particular an antenna and / or a GPS receiver, in order to receive data that can influence the planned route.

In 3 is a flowchart for the selection of the most cost-effective control subroutine S _sel by the mode coordinator 88 shown. _{In this case, three partial control programs S 1} , S ₂ , S _{3 that} can be executed at an operating point BP to achieve the goal are generated by the operating mode coordinator 88 the control _sub- program S sel selected, which causes the lowest operating costs and in particular the lowest fuel consumption. The operating mode coordinator takes this into account 88 in the selection of the control program unit S _sel the current target value _is z, the current operating cost _is k and the current constraints _N.

In 4th an evaluation scheme for selecting the most cost-effective control sub-program S _{sel is} shown. The operating mode coordinator has 88 basically the task of achieving the best possible compromise between target values and costs and selecting _{the associated operating mode and the control sub-program S sel.} For all operating modes BA2, BA5 available for selection here, it has already been checked that the target value and secondary conditions are met. Based on this preselection and the cost functions associated with operating modes BA2 and BA5, the operating mode with the lowest is now Operating costs and the associated control _sub- program S sel selected.

5 shows a cost function in the operation of the internal combustion engine 10 depending on the selected control sub-program S _sel and the associated cost and target value curve. The current actual cost value kist is shown over the distance s covered. The cost function K takes into account the activation costs K _inv for the activation of a control sub-program S _n

6th shows schematically an algorithm for selecting the most cost-effective operating mode and the associated control sub-program S _sel . In a method step I, the distance Sp to be traveled by the motor vehicle 100 on the basis of a predication, for example using the data from the navigation system 84 , determined. In particular, the expected speed n _e and the expected torque of the engine M _e are 10 determined. In a method step II, the costs, target values and secondary conditions for the possible operating modes and control subroutines S _{n are} determined. In a method step III, it is checked whether it is to be expected for the operating modes and control subroutines in question that the side effects N will be below the limit value. In a method step IV, the corresponding most cost-effective operating mode of the internal combustion engine is then determined on the basis of the costs, target values and secondary conditions 10 and the associated subprogram S _sel selected.

The cold start represents for the operating mode coordinator 88 a special case. When the exhaust system is cold 20th are the exhaust aftertreatment components 46 , 48 , 52 , 56 initially not or only partially functional. As a result, it is not possible to adhere to the target value limits in this phase. One of the most important functions of the engine control unit 80 is therefore the rapid heating of the exhaust aftertreatment components 46 , 48 , 52 , 56 .

Another special feature is that the activation duration of the control _{sub-programs S n} in the cold start phase depends less on the driving profile or the speed-load range of the internal combustion engine 10 depends, but mainly on the temperature profile in the exhaust gas aftertreatment components 46 , 48 , 52 , 56 .

In a preferred embodiment of the method it is therefore provided that whenever target value limits cannot be met temporarily, that operating mode and that control subprogram are selected for which the lowest target values are predicted.

List of reference symbols

10

Internal combustion engine

12th

Combustion chamber

14th

Fuel injector

16

inlet

18th

Outlet

20th

Air supply system

22nd

Air filter

24

Air mass meter

26th

compressor

28

Intake duct

30th

throttle

32

Intercooler

34

High pressure exhaust gas recirculation

36

Exhaust gas recirculation line

38

Exhaust gas recirculation valve

40

Exhaust system

42

Exhaust duct

44

turbine

46

Oxidation catalyst

48

Particle filter

50

first metering element

52

SCR coating

54

second metering element

56

SCR catalytic converter

58

Barrier catalytic converter

60

Exhaust gas turbocharger

62

NOx sensor

64

Temperature sensor

66

Differential pressure sensor

68

branch

70

Low pressure exhaust gas recirculation

72

Exhaust gas recirculation cooler

74

Exhaust gas recirculation valve

76

Exhaust gas recirculation duct

78

Exhaust flap

80

Control unit

82

NOx storage catalytic converter

84

navigation system

86

Data transfer system

88

Operating mode coordinator

90

Storage

92

Arithmetic unit

94

Program code

100

Motor vehicle

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• DE 102016112610 B4 [0004]

Claims (10)

Method for operating an internal combustion engine (10) which is connected to a control unit (80) in which several control subprograms (S _n ) for operating the internal combustion engine (10) are stored, with an operating mode coordinator (88) each selected from the control unit (80) stored control program units (S _n), a control program unit (S _sel) is selected to be adhered to which the current legal framework, characterized in that, for a plurality of possible to comply with the legal framework control part programs (S _n), the control program unit (S _sel ) is selected which causes the lowest operating costs. Procedure according to Claim 1 , characterized in that the corresponding subprogram (S _sel ) is selected which has the lowest fuel consumption at this operating point of the internal combustion engine (10). Procedure according to Claim 1 or 2 , characterized in that the corresponding subprogram (S _sel ) is selected which has the lowest consumption of auxiliary resources at this operating point of the internal combustion engine (10). Method according to one of the Claims 1 until 3 , characterized in that the selection of the corresponding control sub-program (S _sel ) by the operating mode coordinator (88) is used for exhaust gas temperature management of the internal combustion engine (10). Method according to one of the Claims 1 until 4th , characterized in that a cost function is stored in the control unit (80) of the internal combustion engine (10) for each control sub-program (S _n). Procedure according to Claim 5 , characterized in that the cost function includes activation costs for the activation of the control sub-program (S _n ) and operating costs for the implementation of the control sub-program (S _n ). Method according to one of the Claims 1 until 6th , characterized in that the control sub-program (S _sel ) with the lowest operating costs is selected on the basis of a prediction of the duration of activity of the selected control sub-program (S _sel ). Procedure according to Claim 7 , characterized in that the selection of the control sub-program (S _sel ) is determined on the basis of statistics from driving cycles and / or driving situations carried out by the driver. Procedure according to Claim 7 or 8th , characterized in that the calculation is carried out using a model of the driving situation and the resulting courses of the operating parameters and / or using an estimate from predictive route data for the planned route. Control unit (80) for carrying out a method according to one of the Claims 1 until 9 , characterized in that the control device (80) has a memory (90) and a computing unit (92), a machine-readable program code (94) being stored in the memory (90), the machine-readable program code (94) being executed by the computing unit (92) a method according to one of the Claims 1 until 9 executes.

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