DE102019210027A1 - Method for determining at least one adaptation value of an exhaust gas recirculation rate - Google Patents

Abstract

Method for determining one or more adaptation values of an exhaust gas recirculation rate rEGR during operation of an internal combustion engine (1) which has an exhaust gas recirculation arrangement (2); wherein the internal combustion engine (1) has at least one cylinder (3) with an input side (4) and an output side (5), an air supply line (6) with an unfiltered air inlet (7) being arranged on the input side (4) An exhaust gas line (9) and an exhaust gas recirculation line (10) connecting the exhaust gas line (9) to the air supply line (6) are arranged on the outlet side (5), a recirculated EGR at least via a first control valve (11) arranged in the exhaust gas recirculation line (9) -Exhaust gas mass flow ṁEGR (12) can be regulated.

Description

The invention relates to a method for determining at least one adaptation value (or for regulating) an exhaust gas recirculation rate (or for determining one or more adaptation values for the EGR rate r _EGR ) during the operation of an internal combustion engine.

In an internal combustion engine that has at least one cylinder with an input side and an output side (for discharging the combustion gases from the cylinder into the exhaust line) and an external low-pressure (or high-pressure) exhaust gas recirculation arrangement, the external exhaust gas recirculation arrangement comprises at least one of the exhaust gas line with an air supply line Exhaust gas recirculation line connecting the internal combustion engine. A (first) control valve is arranged in the exhaust gas recirculation line, by means of which an exhaust gas mass flow can be recirculated in a controllable manner from the exhaust gas line into the air supply line. A cooling device for temperature control of the recirculated exhaust gas mass flow and a filter device can also be arranged in the exhaust gas recirculation line.

For the regulation of an exhaust gas recirculation rate in an internal combustion engine with an (external low-pressure or external high-pressure) exhaust gas recirculation arrangement (EGR arrangement), especially in Otto combustion processes but also in diesel combustion processes, very high levels of accuracy are required for modeling the exhaust gas recirculation rate is required. The requirements for accuracy result among other things. through the emission limits set in some cases by law, through the combustion stability required to operate the internal combustion engine, and through the consumption of fuel.

A variety of factors can affect the accuracy of the EGR rate. For example, the accuracy can be influenced by manufacturing tolerances of the various components of the exhaust gas recirculation arrangement. These can be checked in particular during an end-of-line test (that is to say during the manufacture of the internal combustion engine or a motor vehicle) and compensated for by an individual adaptation. Furthermore, the accuracy can be impaired by running time effects of the internal combustion engine, e.g. B. by sooting the cooling device, by a faulty pressure sensor, etc.

It is precisely these runtime effects that should be recognized and, if necessary, compensated for using suitable measures.

So far known is z. B. that a correction of the mass balance (mass flow in the cylinder, mass flow of raw air or fresh air and mass flow of recirculated exhaust gas) is made using a differential pressure on a (first) valve that regulates the exhaust gas recirculation rate. It is also known to perform a multi-model adaptation for a camshaft phasing.

From the DE 10 2004 029 642 A1 a method for the self-learning parameterization of parameterizable models and for the determination of systematic errors in system models is known. The exact determination of the fresh air mass supplied to an engine and the determination of the model parameters to describe the systematic errors of the sensors used there are explained as an example.

From the DE 10 2011 017 779 A1 a method for determining the low-pressure exhaust gas recirculation mass flow in the air system of an internal combustion engine is known. A fresh air mass flow is determined via a fresh air mass sensor.

From the DE 10 2016 205 680 A1 a method and a device for determining a fresh air mass flow in an internal combustion engine are known. An alternative solution for determining the fresh air mass flow with a hot-film air mass meter is proposed. A pressure difference on the charge air cooler is used.

The object of the present invention is to at least partially solve the problems cited with reference to the prior art. In particular, a method for regulating an exhaust gas recirculation rate is to be proposed, the regulation being carried out with increased accuracy through the adaptation.

A method with the features according to claim 1 contributes to achieving these objects. Advantageous further developments are the subject of the dependent claims. The features listed individually in the patent claims can be combined with one another in a technologically meaningful way and can be supplemented by explanatory facts from the description and / or details from the figures, with further design variants of the invention being shown.

1. a) Betrieb der Verbrennungskraftmaschine in einem oder mehreren Betriebspunkten; wobei für eine erste Gruppe mit einer Mehrzahl von Betriebspunkten i, mit i = 1 bis n (wobei n eine natürliche Zahl ist), ein zumindest teilweise geöffnetes erstes Regelventil und für eine zweite Gruppe mit einer Mehrzahl von Betriebspunkten j, mit j = 1 bis m (wobei m eine natürliche Zahl ist), ein geschlossenes erstes Regelventil vorliegt;
2. b) Ermitteln eines Messwerts oder eines Modellwerts der Lambdaregelung oder eines Lambdawertes (z.B. des Abgases in der Abgasleitung) für jeden Betriebspunkt und Berechnen eines EGR-Faktors f_EGRij für jedes Betriebspunktpaar; und
3. c) Erstellen einer Massenbilanz (aus z. B. Modell- oder Messwerten) zumindest für die erste Gruppe (oder für beide Gruppen) von Betriebspunkten nach der Bedingung ṁ_Zyl- ṁ_Luft-ṁ_EGR, mit ṁ_EGR= 0 für Betriebspunkte j der zweiten Gruppe (bei geschlossenem ersten Regelventil liegt kein EGR-Abgasmassenstrom ṁ_EGR vor; ṁ_Zyl ist der über den Zylinder strömende Massestrom; ṁ_Luft ist der dem Zylinder zugeführte Rohluftmassenstrom); und Berechnen eines Luft-Faktors f_Luftij für jeden Betriebspunkt beider Gruppen;
4. d) Berechnen und Einstellen der (bzw. Korrektur der modellierten, gemessenen oder berechneten) Abgasrückführungsrate (in einem bevorzugt beliebigen Betriebspunkt) nach der Bedingung: $${\text{r}}_{\text{EGR}}={\text{f}}_{\text{EGR}}\ast {\dot{\text{m}}}_{\text{EGR}}/\left({\text{f}}_{\text{EGR}}\ast {\dot{\text{m}}}_{\text{EGR}}+{\text{f}}_{\text{Luft}}\ast {\dot{\text{m}}}_{\text{Luft}}\right).$$
   

The invention relates to a method for determining an adaptation value or a plurality of adaptation values (or for regulating) an exhaust gas recirculation rate r _{EGR when} an internal combustion engine is in operation. The internal combustion engine has an (external low-pressure or external high-pressure) exhaust gas recirculation arrangement. The internal combustion engine furthermore has at least one cylinder (with a combustion chamber for the combustion of at least air and fuel and for driving a piston moving in the cylinder) with an input side (for introducing air and possibly exhaust gas from an exhaust gas recirculation line and possibly fuel and / or or additives) and an output side (for carrying the combustion gases out of the cylinder into the exhaust pipe). An air supply line with a raw air inlet or a fresh air inlet and possibly a second control valve (a throttle valve) is arranged or connected on the inlet side. On the outlet side, an exhaust gas line and an exhaust gas line connecting the exhaust gas line to the air supply line (upstream or downstream of the second control valve, if present, connecting the exhaust gas recirculation line) are arranged or connected. At least via a first control valve arranged in the exhaust gas recirculation line there is an (from the exhaust gas line via the exhaust gas recirculation line EGR exhaust gas mass flow ṁ _EGR (exhaust gas mass flow in e.g. [kilograms / hour]) _recirculated into the air supply line and via the inlet side into the cylinder) can be regulated (i.e. adjustable with regard to the mass flow). The method comprises at least the following steps:

1. a) operation of the internal combustion engine in one or more operating points; where for a first group with a plurality of operating points i, with i = 1 to n (where n is a natural number), an at least partially open first control valve and for a second group with a plurality of operating points j, with j = 1 to m (where m is a natural number), a closed first control valve is present;
2. b) determining a measured value or a model value of the lambda control or a lambda value (for example of the exhaust gas in the exhaust line) for each operating point and calculating an EGR factor f _EGRij for each operating _{point pair} ; and
3. c) Creation of a mass balance (from e.g. model or measured values) at least for the first group (or for both groups) of operating points according to the condition ṁ _Cyl - ṁ _Air -R _EGR , with ṁ _EGR = 0 for operating points each second group (when the first control valve is closed, there is no EGR exhaust gas mass flow ṁ _EGR ; ṁ _cyl is the mass flow flowing over the cylinder; ṁ _air is the raw _air mass flow supplied to the cylinder); and calculating an air factor f _Luftij for each operating point of both groups;
4. d) Calculating and setting the (or correcting the modeled, measured or calculated) exhaust gas recirculation rate (at any preferred operating point) according to the condition: $${\text{r}}_{\text{EGR}}={\text{f}}_{\text{EGR}}\ast {\dot{\text{m}}}_{\text{EGR}}/\left({\text{f}}_{\text{EGR}}\ast {\dot{\text{m}}}_{\text{EGR}}+{\text{f}}_{\text{air}}\ast {\dot{\text{m}}}_{\text{air}}\right).$$
   

In particular, a second control valve (a throttle valve) is also arranged in the air supply line (e.g. in the case of an Otto engine). In particular, an EGR exhaust gas mass flow ṁ _EGR (exhaust gas mass flow in e.g. [kilograms / hour]) and via the second is then via the first control valve arranged in the exhaust gas recirculation line (from the exhaust gas line via the exhaust gas recirculation line into the air supply line and via the inlet side into the cylinder) Control valve a total mass flow or cylinder mass flow ṁ _cyl (i.e. a sum of EGR exhaust gas mass flow ṁ _EGR and raw _air mass flow ṁ _air that is directed from an environment into the air supply line to the cylinder) controllable.

The above (non-exhaustive) division of the process steps into a) to d) is primarily intended only to serve as a distinction and not to force a sequence and / or dependency. The frequency of the process steps z. B. during operation of the internal combustion engine can vary. It is also possible that process steps overlap at least partially in time. In particular, steps a) to d) are carried out in the order mentioned, steps b) to d) taking place in particular during step a). Steps b) and c), if appropriate also b) to d), are in particular carried out repeatedly.

In particular, according to step d), the exhaust gas recirculation rate (for a currently existing operating point) is calculated taking into account the values already determined for the EGR factor f _EGRij and air factor f _Luftij and set on the internal combustion engine for each currently existing operating point. In particular, the current state of the internal combustion engine or the components influencing the exhaust gas recirculation rate is taken into account by the factors.

In particular, it should be ensured in this way that an exhaust gas recirculation rate provided for an operating point (which is required, for example, to comply with emission limits) is actually set.

In particular, on the basis of steps b) and c), a state of the exhaust gas recirculation arrangement (continuously or periodically during the running time of the internal combustion engine) is checked, so that the intended “target exhaust gas recirculation rate” also for a currently present operating point is actually feasible. According to steps b) and c), factors are determined for individual operating points.

In particular, these factors for performing step d) are combined into a characteristic map so that the appropriate factor can then be determined from the characteristic map for any operating point.

These factors are preferably combined to form a value for the EGR factor f _ECR and for the air factor f _air for performing step d).

For this combination of the individual factors into an EGR factor and air factor valid for all operating points, a mathematical check of the calculated factors can be provided before they are actually used for regulating the exhaust gas recirculation rate. In particular, the determined factors can only be used to set the exhaust gas recirculation rate if the check is successful (i.e. if the result is plausible) (e.g. as part of a step size control).

In particular, an unfiltered air flap can be provided as a further (third) control valve in the air supply line, upstream of the confluence of the exhaust gas recirculation line in the air supply line. In particular, the raw air flap is used to generate a defined differential pressure across the first control valve. As a result, higher levels of accuracy can be achieved at operating points with an otherwise low differential pressure. Alternatively, e.g. For example, an exhaust flap can also be used in the exhaust pipe, e.g. in the diesel combustion process.

In particular, the internal combustion engine does not include a device for charging or for increasing the boost pressure of the internal combustion engine.

In particular or as an alternative, the internal combustion engine comprises a device for charging or for increasing a boost pressure of the internal combustion engine. In particular, an exhaust gas turbocharger or a similar device is provided, with z. B. can be driven by a turbine arranged in the exhaust gas flow, a compressor which can generate a pressure increase in the air supply line.

In particular, the device is arranged in the exhaust line between the outlet side and the exhaust gas recirculation line and in the air supply line between the exhaust gas recirculation line and the inlet side. In this case, the exhaust gas recirculation arrangement forms an external low-pressure exhaust gas recirculation arrangement.

Alternatively, the device is arranged in the exhaust line such that the exhaust gas recirculation line is provided between the outlet side and the device (that is, upstream of the device). The device is arranged in the air supply line in particular between the exhaust gas recirculation line and the raw air inlet (that is, upstream of the exhaust gas recirculation line). In this case, the exhaust gas recirculation arrangement forms an external high pressure exhaust gas recirculation arrangement.

In particular, the second control valve is arranged upstream of the exhaust gas recirculation line and preferably downstream of the device.

In particular, an EGR factor f _EGRij can be calculated for each operating point in step b). This EGR factor compensates for a deviation of the EGR exhaust gas mass flow from a “target EGR exhaust gas mass flow”. In particular, the composition of the exhaust gas in the exhaust line can be determined using lambda probes. From the recorded manipulated variable of the mixture control or a recorded lambda value compared to a “target lambda value”, z. B. the EGR factor can be determined.

In particular, in step c) an air factor f _airij can be determined for each operating point of the at least first or both groups. For this purpose, a mass balance is taken into account at least for the first group of operating points according to the condition ṁ _Cyl - ṁ _Air - ṁ _EGR , with ṁ _EGR = 0 for operating points j of the second group (with the first control valve closed). A deviation of the raw air mass flow from a “target raw air mass flow” is compensated by this air factor. This z. B. a change occurring at the second control valve can be recognized and compensated by the air factor.

In particular, the mass flow flowing over the cylinder can be determined from existing data of a control device of the internal combustion engine (e.g. from data from the fuel injection system, from measured values determined by pressure sensors, characteristic maps, etc.).

In particular, the results determined in each of steps b) and c) can be used for the respective other step c) and b). In particular, a mutual check (e.g. for plausibility) of the determined values is possible.

In particular, errors or deviations in the The raw air mass flow and the EGR exhaust gas mass flow are detected and compensated for by the factors mentioned. For this purpose, operating points are passed through in EGR mode (i.e. with the first control valve at least partially open) and in non-EGR mode (i.e. with the first control valve closed), and the values determined are compared with one another (with the formation of pairs of operating points i and j) and characteristic values (the factors) formed. This is intended, in particular, to eliminate other sources of error (i.e. apart from EGR exhaust gas mass flow and raw air mass flow). The two determined factors are, in particular by means of a least square method (see e.g. EP 1 715 165 A2 such as DE 10 2004 029 642 A1 ) recorded and calculated at a certain number of operating points.

In particular, an adaptation of the raw air mass flow and the EGR exhaust gas mass flow can be decoupled from one another by the method (that is to say by calculating the two factors).

In particular, each operating point includes stationary operating conditions of the internal combustion engine.

• • Drehzahl einer (über den in dem Zylinder bewegten Kolben angetriebenen) Kurbelwelle der Verbrennungskraftmaschine;
• • EGR-Abgasmassenstrom ṁ_EGR;
• • Rohluftmassenstrom bzw. Frischluftmassenstrom ṁ_Luft;
• • Lambdawert (des Abgases).

In particular, a stationary operating condition includes that at least the following parameters during steps b) and c) a deviation (i.e. a change in the respective parameter within the considered time interval, which is required for performing step b) or c)) from each for example at most 5%, preferably at most 2%:

• • speed of a crankshaft (driven by the piston moving in the cylinder) of the internal combustion engine;
• • EGR exhaust gas mass flow ṁ _EGR ;
• • Raw air mass flow or fresh _air mass flow ṁ _air ;
• • Lambda value (of the exhaust gas).

In particular, the raw _air mass flow ṁ _{air is} determined by a sensor or model.

In particular, the sensor is a (known) hot-film air mass sensor.

In particular, changes that occur (which, for example, influence the accuracy of the regulation of the second regulating valve or the throttle valve) are compensated for at the hot-film air mass sensor by the air factor.

• • pus (ein erster Druck in der Abgasrückführungsleitung stromaufwärts des ersten Regelventils),
• • p_DS (ein zweiter Druck in der Abgasrückführungsleitung stromabwärts des ersten Regelventils), und
• • Tus (eine Temperatur des Abgases im Bereich des ersten Regelventils oder stromaufwärts des ersten Regelventils)

ermittelt.In particular, the EGR exhaust gas mass flow ṁ _EGR , taking the parameters into account

• • pus (a first pressure in the exhaust gas recirculation line upstream of the first control valve),
• • p _DS (a second pressure in the exhaust gas recirculation line downstream of the first control valve), and
• • Tus (a temperature of the exhaust gas in the area of the first control valve or upstream of the first control valve)

determined.

mit

• Aeff: effektive Querschnittsfläche des ersten Regelventils;
• R: spezifische Gaskonstante;
• Ψ: Durchflussfunktion;
• K: Isentropenexponent.

In particular, the EGR exhaust gas mass flow z. B. on the basis of the following (known) equation (whereby detection via sensors or a map is also possible): $${\dot{\text{m}}}_{\text{EGR}}={\text{A.}}_{\text{eff}}\ast {\text{p}}_{\text{US}}\ast {\left(2/\left(\text{R.}\ast {\text{T}}_{\text{US}}\right)\right)}^{1/2}\ast \mathrm{\Psi }\left(\text{k},{\text{p}}_{\text{US}}/{\text{p}}_{\text{DS}}\right)$$

With

• Aeff: effective cross-sectional area of the first control valve;
• R: specific gas constant;
• Ψ: flow function;
• K: isentropic exponent.

In particular, the number of operating points for the first group corresponds to the number of operating points for the second group. The factors f _EGRij and f _Luftij determined for the individual operating _points are read out and combined in a least-square procedure to form a factor f _EGR and f _air , which applies to an entire operating map of the internal combustion engine (and according to step d) for the calculation and setting the EGR rate is used).

In particular, the first group and the second group each comprise at least five different operating points.

In particular, the method is carried out continuously or (preferably) periodically (that is to say at certain time intervals).

A motor vehicle is also proposed, at least having an internal combustion engine and a control device (a control device), the internal combustion engine having an (external low-pressure or external high-pressure) exhaust gas recirculation arrangement and at least one cylinder with an input side and an output side. An air supply line with an unfiltered air inlet (and possibly a second control valve) is arranged on the inlet side. At the outlet side is an exhaust pipe and one that Exhaust gas line with the air supply line (upstream or downstream of the possibly present second control valve) connecting exhaust gas recirculation line is arranged. During operation of the internal combustion engine, a recirculated EGR exhaust gas mass flow ṁ _EGR (and - if available - via the second control valve a raw _air mass flow ṁ _air or a total mass _flow or a cylinder mass _flow ) for setting an exhaust gas recirculation rate r _EGR is provided at least via a first control valve arranged in the exhaust gas recirculation line adjustable. At least the setting of the exhaust gas recirculation rate and the regulation of the at least one regulating valve (possibly both regulating valves or all regulating valves) are carried out by the control device. The control device is designed or equipped, configured or programmed to carry out the described method.

The statements relating to the method can in particular be transferred to the motor vehicle and vice versa.

Furthermore, the method can also be carried out by a computer or with a processor of the control device.

Accordingly, a system for data processing is also proposed which comprises a processor which is adapted / configured in such a way that it carries out the method or part of the steps of the proposed method.

A computer-readable storage medium can be provided which comprises instructions which, when executed by a computer / processor, cause the latter to execute the method or at least some of the steps of the proposed method.

The statements relating to the method can in particular be transferred to the motor vehicle or the computer-implemented method (that is to say the computer or the processor, the data processing system, the computer-readable storage medium) and vice versa.

In particular, the method can run as described below, the description of the individual steps also being valid regardless of the sequence described here and being combinable with other features of the method.

After the internal combustion engine has been started, in one step 1 ) Prerequisites are queried.

The following points can be checked to determine to what extent there are prerequisites for an adaptable (external low-pressure or external high-pressure) exhaust gas recirculation system: First, the mass flow controllers relevant for the EGR system, i.e. the first control valve and, if applicable, the second control valve, are adjusted to their sensory and physical plausibility and correctness are queried. The plausibility or correctnesses themselves are determined beforehand, e.g. B. as part of the so-called end-of-line test, in the so-called engine control unit run-on or before the current start of the internal combustion engine. In this step 1 ) the current characteristic values are checked for their existence or formal validity. In addition, useful operating conditions (operating mode, map area, etc.) are checked for system adaptation or for the process.

If the preconditions are met, it can be done in one step 2 ) a query is made regarding the presence of a stationary operating point. In this step 2 ) an operating point is checked for compliance with the criteria describing stationary operation (e.g. speed of the crankshaft, raw air mass flow, EGR mass flow, mixing ratio, i.e. lambda value, etc.). These criteria can be specifically defined for the present external low-pressure exhaust gas recirculation arrangement. A so-called stationary operation present in several dimensions is in particular a prerequisite for the further successful course of the system adaptation or the described method. For the positive detection of so-called stationary operation, a targeted selection of operating parameters is observed in their respective temporal course, subjected to a gradient calculation in an adapted time window and this gradient is each specific limitations, i.e. in the sense of stationary operation signed, permissible limit values (minimum and maximum values) juxtaposed. Stationary operation in the sense of this query is when all parameters of the above-mentioned relevant selection simultaneously meet the individual criteria at the present time and thus stationary operation in the sense of system adaptation is present in the form of a logical AND link.

If the operating point is stationary, it can be done in one step 3 ) a query is made regarding the use of the external low-pressure exhaust gas recirculation system. Here, from the point of view of the EGR system adaptation, it can be determined whether either an operation of the internal combustion engine without using the exhaust gas recirculation arrangement (ie closed first control valve) or an operation of the internal combustion engine with conscious use of the exhaust gas recirculation system (ie an at least partially open first control valve and possibly another existing one (third) control valve (unfiltered air flap) in position control mode) present. The distinction between the two operating states (with or without the use of the exhaust gas recirculation system), which are present in the sense of the system adaptation or the method at the respective point of consideration, is particularly (decisive) importance for the further logically and physically correct processing of the data or measurement data obtained subsequently.

In a next step 4th ) the determination and storage of characteristic values for the holistic, factorial description of the so-called mixture deviation or the correction requirement from the perspective of the lambda control takes place. The physical basis of the system adaptation of the external low-pressure exhaust gas recirculation arrangement considered here is the determination of characteristic values that a factorial, ie multiplicative correction action of the lambda control that applies to the observation point in time or for a defined observation period in order to adjust the present "actual value" of the air ratio lambda to the Engine control (e.g. provided in the control device) describes the predetermined “setpoint” of the air ratio lambda. As a basis there are one or more, e.g. B. three separately determined characteristic values equipped with specific physical meanings (e.g. manipulated variable lambda control, mixture adaptation offset and mixture adaptation gain) that describe the action of the above-mentioned lambda control. In this step, these three characteristic values given from the point of view of the system adaptation or the process, together with a larger number of further operating characteristic values, based on the so-called mixture basic arithmetic _chain present in the engine control unit, become one of the _{above-mentioned} characteristic values (EGR factor f _EGRij ) , factorial description of the so-called mixture deviation or the need for correction from the perspective of the lambda control. The operating parameters required for this as input variables of the above equation are obtained over a defined period of time at a defined sampling frequency, ie thus in a specific number of sampling steps. The above equation for determining the characteristic value for the holistic, factorial description of the so-called mixture deviation or the correction requirement from the perspective of the lambda control is solved with the same frequency, ie in the respective sampling step. This set of characteristic values is stored in specific storage locations in association with the two operating modes.

When the internal combustion engine is in operation without using the exhaust gas recirculation arrangement (i.e. closed first control valve and (if available) fully open unfiltered air flap), a mass balance of all gas mass flows present in the internal combustion engine and flowing during engine operation is also formed via a parameterizable number of sampling steps in order to determine the measured value of the called. to determine the hot-film air-mass sensor an factorial correction value (air factor f _Luftij) so that the above-mentioned mass balance after application of the aforementioned factorial correction value (air factor f _Luf -tij) correct for the measured value of the so-called. hot-film air-mass sensor present. The above-mentioned factorial correction _value (air factor f _airij ) is also stored in specific memory locations (e.g. in the control device).

As part of a further step 5 ) can query the in step 4th ) stored data. For reasons of physical plausibility and mathematical stability, in both operating states (with or without the use of the exhaust gas recirculation arrangement), in particular, an equal amount of step 4th ) obtained characteristic values of the factorial lambda correction with reference to the engine operating point have been stored in order to represent a further usable state in terms of the system adaptation or the method. The amount of data that can be used positively in the above sense can be parameterized.

In a further step 6th ), if sufficient data is available, the above and within the framework of the step 4th ) (or of method steps b) and c)) data-occupied storage locations for the amount of factorial air correction _values (air factor f _Luftij ) and factorial lambda correction _values (EGR factor f _EGRij ) are read out and a so-called _lease -squares method z. B. be supplied on the basis of a so-called matrix solver. Alternatively, an iterative or analytical method can also be used as the calculation method. This procedure according to step 6th ) is particularly necessary and sensible, since the physical statement on the final adaptive correction requirement with recirculated EGR exhaust gas mass flow ṁ _EGR and exhaust gas recirculation mass flow ṁ _air (i.e. the core task and the end goal of the described system adaptation - or the method - of the existing exhaust gas recirculation arrangement) on the individually considered or The evaluated operating point may differ in magnitude and sign compared to the statement at another operating point. In the functional definition of the system adaptation or the method there is only one factorial air correction value valid for the entire operating map of the engine (i.e. only one air factor f _air ) and only one comparable factorial lambda correction value (i.e. only one EGR Factor f _EGR ). In particular, it must be possible to determine a solution for both factors that can be checked for mathematical trustworthiness. If the solution is successful, both factors for raw air mass flow and EGR exhaust gas mass flow are applied and a new run through all steps (the steps identified above 1 ) to 6) or a) to d) started.

A control device of an internal combustion engine is also proposed, the internal combustion engine being designed with an (external low-pressure or external high-pressure) exhaust gas recirculation arrangement having at least one (first) control valve, and means are also provided which are suitable for the steps of a method of the type proposed here.

In addition, a computer program product should also be recorded, comprising commands which have the effect that the control device (at least partially) executes the method steps specified here.

If the control device and / or the exhaust gas recirculation arrangement and / or the (first) control valve for this purpose should be able to be monitored and / or controlled by the control device by means of sensors and / or actuators, reference can be made in full to the further explanations and the system supplemented.

As a precaution, it should be noted that the numerals used here (“first”, “second”, ...) primarily (only) serve to distinguish between several similar objects, sizes or processes, so in particular no dependency and / or sequence of these objects, sizes or prescribe processes to each other. Should a dependency and / or sequence be required, this is explicitly stated here or it is obvious to the person skilled in the art when studying the specifically described embodiment. If a component can occur several times (“at least one”), the description of one of these components can apply equally to all or part of the majority of these components, but this is not mandatory.

The invention and the technical environment are explained in more detail below with reference to the accompanying figure. It should be pointed out that the invention is not intended to be restricted by the exemplary embodiment cited. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figure and to combine them with other components and findings from the present description. In particular, it should be pointed out that the figure and in particular the size relationships shown are only schematic. 1 shows a motor vehicle 19th with an internal combustion engine 1 and a control device 20th .

The internal combustion engine 1 has an external low-pressure exhaust gas recirculation arrangement 2 and a plurality of cylinders 3 with an entry page 4th and an exit page 5 on. On the entrance side 4th is an air supply line 6th with a raw air inlet 7th and one at the unfiltered air inlet 7th arranged filter, a raw air flap 26th and a second control valve 8th arranged. On the exit side 5 is an exhaust pipe 9 and one, the exhaust pipe 9 with the air supply line 6th upstream of the second control valve 8th and downstream of the unfiltered air flap 26th connecting exhaust gas recirculation line 10 arranged. During operation of the internal combustion engine 1 are via one in the exhaust gas recirculation line 10 arranged first control valve 11 a recirculated EGR exhaust gas mass flow ṁ _EGR 12 and via the second control valve 8th a raw _air mass flow ṁ _air 13 or a total mass flow or cylinder mass flow (sum of raw _air mass flow and EGR exhaust gas mass flow) for setting an exhaust gas recirculation rate r _EGR . At least the setting of the exhaust gas recirculation rate and the regulation of the control valves 8th , 11 , 26th is done by the control device 20th .

The raw _air mass flow ṁ _air 13 is measured by a hot-film air mass sensor 15th determined. Changes that occur (e.g. the accuracy of the control of the second control valve 8th affect) on the hot film air mass sensor 15th are compensated by the air factor.

The EGR exhaust gas mass flow ṁ _EGR 12 is calculated taking into account a first pressure pus 16 in the exhaust gas recirculation line 10 upstream of the first control valve 11 , a second pressure p _DS 17 in the exhaust gas recirculation line 10 downstream of the first control valve 11 , and a temperature tus 18th of the exhaust gas upstream of the first control valve 11 determined.

To determine a steady-state operating condition, among other things a speed of rotation above that in the cylinder 4th moving piston driven, crankshaft 14th the internal combustion engine 1 be taken into account.

The internal combustion engine 1 comprises a device for charging or for increasing a boost pressure of the internal combustion engine 1 . That's why there's an exhaust gas turbocharger here 21st provided by one in the exhaust gas flow of the exhaust pipe 9 arranged turbine 22nd one in the air supply line 6th arranged compressor 23 is drivable.

In the exhaust gas recirculation line 10 are a filter 24 as well as a cooler 25th arranged. The exhaust gas recirculation line 10 opens upstream of the second control valve 8th into the air supply line 6th .

List of reference symbols

1

Internal combustion engine

2

Exhaust gas recirculation arrangement

3

cylinder

4th

Entry page

5

Exit page

6th

Air supply line

7th

Raw air intake

8th

second control valve

9

Exhaust pipe

10

Exhaust gas recirculation line

11

first control valve

12

EGR exhaust gas mass flow ṁ _EGR

13

Raw _air mass flow ṁ _air

14th

crankshaft

15th

Hot film air mass sensor

16

first pressure pus

17th

second pressure p _DS

18th

Temperature tus

19th

Motor vehicle

20th

Control device

21st

Exhaust gas turbocharger

22nd

turbine

23

compressor

24

filter

25th

cooler

26th

Raw air flap

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 102004029642 A1 [0007, 0031]
• DE 102011017779 A1 [0008]
• DE 102016205680 A1 [0009]
• EP 1715165 A2 [0031]

Claims (12)

Method for determining one or more adaptation values of an exhaust gas recirculation rate r _EGR during operation of an internal combustion engine (1) which has an external exhaust gas recirculation arrangement (2); wherein the internal combustion engine (1) has at least one cylinder (3) with an input side (4) and an output side (5), an air supply line (6) with an unfiltered air inlet (7) being arranged on the input side (4) An exhaust gas line (9) and an exhaust gas recirculation line (10) connecting the exhaust gas line (9) to the air supply line (6) are arranged on the outlet side (5), a recirculated EGR at least via a first control valve (11) arranged in the exhaust gas recirculation line (9) Exhaust gas mass flow ṁ _EGR (12) can be regulated; wherein the method comprises at least the following steps: a) operation of the internal combustion engine (1) in one or more operating points; wherein for a first group with one or a plurality of operating points i, with i = 1 to n, an at least partially open first control valve (11) and for a second group with one or a plurality of operating points j, with j \ = 1 to m, a closed first control valve (11) is present; b) determining a measured value or a model value of the manipulated variable of the lambda control or a lambda value for each operating point and calculating an EGR factor f _EGRij for each operating point; and c) creating a mass balance at least for the first group of operating points according to the condition ṁ _cyl - ṁ _air - ṁ _EGR , with ṁ _EGR = 0 for operating points j of the second group; and calculating an air factor f _airij for each operating point of the groups; where ṁ _air (13) denotes the raw air mass flow supplied to the at least one cylinder (3); d) Calculating and setting the exhaust gas recirculation rate according to the condition: $${\text{r}}_{\text{EGR}}={\text{f}}_{\text{EGR}}\ast {\dot{\text{m}}}_{\text{EGR}}/\left({\text{f}}_{\text{EGR}}\ast {\dot{\text{m}}}_{\text{EGR}}+{\text{f}}_{\text{air}}\ast {\dot{\text{m}}}_{\text{air}}\right)$$

Procedure according to Claim 1 , each operating point comprising steady-state operating conditions of the internal combustion engine (1). Procedure according to Claim 2 , wherein a stationary operating condition comprises that at least the following parameters have a deviation of at most 5% during steps b) and c): • speed of a crankshaft (14) of the internal combustion engine (1); • EGR exhaust gas mass flow ṁ _EGR (12); • Raw _air mass flow ṁ _air (13); • Lambda value. Method according to one of the preceding claims, wherein the raw _air mass flow ṁ _air (13) is determined by a sensor. Procedure according to Claim 4 , wherein the sensor is a hot film air mass sensor (15). Method according to one of the preceding claims, wherein the EGR exhaust gas mass flow ṁ _EGR (12) taking into account the parameters • pus, a first pressure (16) in the exhaust gas recirculation line (9) upstream of the first control valve (11), • p _DS , a second Pressure (17) in the exhaust gas recirculation line (9) downstream of the first control valve (11), and • Tus (18), a temperature of an exhaust gas in the area of the first control valve (11) or upstream of the first control valve (11) is determined. Method according to one of the preceding claims, wherein the number of operating points for the first group corresponds to the number of operating points for the second group; The factors f _EGRij and f _Luftij determined for the individual operating _{points are} read out and combined within the framework of a least-square method to form a factor f _EGR and f _air each, which applies to an entire operating map of the internal combustion engine (1). Method according to one of the preceding claims, wherein the first group and the second group each comprise at least five different operating points. Method according to one of the preceding claims, wherein the method is carried out periodically. Motor vehicle (19), at least having an internal combustion engine (1) and a control device (20), the internal combustion engine (1) having an exhaust gas recirculation arrangement (2) and at least one cylinder (3) with an input side (4) and an output side (5) ; an air supply line (6) with an unfiltered air inlet (7) being arranged on the inlet side (4), an exhaust gas line (9) and an exhaust gas recirculation line (6) connecting the exhaust gas line (9) to the air supply line (6) on the outlet side (5). 10) is arranged, wherein during operation of the internal combustion engine (1) a recirculated EGR exhaust gas mass flow ṁ _EGR (12) for setting an exhaust gas recirculation rate r _{EGR can be} regulated at least via a first control valve (11) arranged in the exhaust gas recirculation line (10); wherein at least the setting of the exhaust gas recirculation rate and the regulation of the at least one regulating valve (11) takes place by the control device (20); where the Control device (20) is designed to be suitable for performing the method according to one of the preceding claims. Control device (20) of an internal combustion engine (1) with a low-pressure exhaust gas recirculation arrangement (2), having at least one control valve (11) and means which are suitable for the steps of a method according to one of the Claims 1 to 9 execute. Computer program product, comprising instructions which cause the control device of the Claim 11 the process steps according to one of the Claims 1 to 9 executes.

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