DE102018213809A1 - Method and device for operating an internal combustion engine with a throttle valve and with an exhaust gas recirculation system for detecting a soaked EGR line - Google Patents

Abstract

Method and device for carrying out the method, which provides the following steps: opening an exhaust gas recirculation valve (108) of an internal combustion engine (100), closing a throttle valve (104) of the internal combustion engine (100), detecting a value for an intake manifold pressure of the internal combustion engine (100) when the exhaust gas recirculation valve ( 108) and closed throttle valve (104), comparing the value with a first threshold value and a second threshold value (B) which is greater than the first threshold value, recognizing an operating state of the internal combustion engine (100), depending on whether the value lies in a value range between the first threshold and the second threshold (B) or outside this range. This makes it possible to monitor various air system components, in particular sooting the EGR return path, and enables “pin pointing”, which can also be used to locate a defective component.

Description

State of the art

The invention relates to a method for operating an internal combustion engine with a throttle valve and with exhaust gas recirculation (EGR). In particular, the invention relates to a method for monitoring an EGR mass flow in which an air system of the internal combustion engine is operated with an open EGR valve and a closed throttle valve.

Revealed for monitoring the EGR mass flow DE 102008041804 A1 that a possibility of error is that sooting can occur in the exhaust gas recirculation arrangement, ie a deposit of soot and oil vapors, which can reduce the flow cross section through lines of the exhaust gas recirculation arrangement or can impair the functioning of the EGR valve. However, sooting cannot be detected by monitoring the control deviation, since in the case of control, this is compensated for by opening the EGR valve to a greater extent or by throttling the fresh air mass by the throttle valve.

Revealed for surveillance DE 10 2008 041 804 A1 the following steps: - performing a control for setting an exhaust gas recirculation rate by closing a throttle valve; - Providing a pressure difference indication which indicates a pressure difference in an air supply section of the internal combustion engine or a pressure difference via the exhaust gas recirculation arrangement; Determining a pressure difference reference value as a function of one or more operating variables of the internal combustion engine; - Detection of an error in the exhaust gas recirculation system depending on the pressure difference specification and the pressure difference reference value.

From the DE 10 2011 100 585 Another monitoring function is known which is based on monitoring a mass flow.

On the other hand, it is desirable to have expanded monitoring that can detect other possible errors.

Disclosure of the invention

Extended monitoring is achieved by the method and the device according to the independent claims.

The method includes opening an exhaust gas recirculation valve of an internal combustion engine, closing a throttle valve of the internal combustion engine, detecting a value for an intake manifold pressure (pressure between the throttle valve and cylinder inlet ducts) of the internal combustion engine with the exhaust gas recirculation valve open and the throttle valve closed, comparing the value with a first threshold value and a second threshold value that is greater than the first threshold value, recognizing an operating state of the internal combustion engine, depending on whether the value lies in a value range between the first threshold value and the second threshold value or outside this range. In this operating state of the internal combustion engine, a value of an intake manifold pressure sensor is compared with the first upper and second lower threshold values. The two threshold values define a range within which the air system operates normally. These values are set for a new engine. The monitoring function can also be used as an application function. If the measured value of the pressure sensor is lower than the lower threshold value, an increased soot of the exhaust gas recirculation (EGR), for example of the EGR cooler, the EGR valve, or an EGR venturi sensor, can be concluded from the soot in the normally operating air system , If the measured value of the pressure sensor is higher than the upper threshold value, there may either be soot in the cylinder intake ports or the throttle valve may have a leak. The latter case would also be recognized, for example, by an electronic throttle valve diagnostic function. This enables monitoring of various air system components and, in particular, sooting of the EGR return path. This also enables pin pointing, ie the defective component can also be localized. The device comprises a combustion chamber into which an air mass flow for combustion in the combustion chamber can be fed via a throttle valve which is arranged in an intake manifold. Exhaust gas from the combustion can be supplied for combustion in the combustion chamber via an exhaust gas recirculation valve which is arranged in an exhaust gas recirculation path. A pressure in the intake manifold can be measured by a pressure sensor. A control device is designed to carry out the method by detecting signals from the pressure sensor and outputting control signals for the throttle valve and the exhaust gas recirculation valve.

The first threshold value or the second threshold value is preferably determined as a function of a parameter which influences the intake manifold pressure. As a result, the monitoring is adapted for different operating states of the internal combustion engine.

The first threshold value or the second threshold value is preferably determined as a function of a rotational speed of the internal combustion engine. The function is possible in a wide range of engine speeds.

The first threshold value or the second threshold value is preferably determined or corrected as a function of an ambient pressure. The function is thus adapted to different ambient pressures, for example for different heights.

The first threshold value and the second threshold value preferably specify a tolerance range that characterizes an operating state in which the internal combustion engine has no sooting. The threshold values define a tolerance range within which the air system is assumed to work normally. For a new engine, for example, these values are determined by application or on the basis of calculations based on design data.

A sooting of an exhaust gas recirculation path of the internal combustion engine, in particular an exhaust gas recirculation cooler or an exhaust gas recirculation venturi sensor in the exhaust gas recirculation path, is preferably detected when the temperature falls below the first threshold value. If the intake manifold pressure drops below the lower threshold value, with the throttle valve closed and the exhaust gas recirculation valve open, it can be concluded that the exhaust gas recirculation path has a sooting that is greater than is desired for a normally operating air system. This reduces the exhaust gas mass flow into the intake manifold, which leads to an overall lower air / exhaust gas pressure in the intake manifold compared to the normally operating air system.

A sooting of a cylinder inlet port of the internal combustion engine or an increased leakage at a throttle valve of the internal combustion engine is preferably detected when the second threshold value is exceeded. If the intake manifold pressure rises above the upper threshold value, with the throttle valve closed and the exhaust gas recirculation valve open, it can be concluded that either one or more cylinder intake ports are sunk or that the throttle valve has a leak. In both cases, the air / exhaust gas pressure in the intake manifold increases compared to the normal working air system.

An air mass flow of the internal combustion engine or an electrical throttle valve diagnosis of the internal combustion engine is preferably evaluated in order to distinguish between an operating state of sooting of the intake manifold and an operating state with the leak on the throttle valve. The electrical throttle valve diagnosis detects a leak in the throttle valve regardless of the monitoring function. If the electrical throttle valve diagnosis does not detect a leak, the intake manifold must be soaked. If the electric throttle valve diagnosis has identified a leak, it is more likely that the monitoring function also recognized this leak and there is no excessive sooting of the intake manifold.

An feed-forward control for an exhaust gas recirculation of the internal combustion engine is preferably adapted and / or parameters for a calculation of an EGR mass flow are adjusted via a measured variable of an EGR venturi tube depending on a result of a comparison of the intake manifold pressure with the first threshold value and the second Threshold value, or an adaptation of a mass flow model of the internal combustion engine depending on a result of a comparison of the intake manifold pressure with the first threshold value and the second threshold value. This improves the control of the internal combustion engine, especially when sooting is detected.

An exhaust gas recirculation mass flow of the internal combustion engine is preferably compared in a comparison with a mass flow into the internal combustion engine, and, depending on the result of the comparison, a soiled exhaust gas recirculation venturi tube, a soaked venturi differential pressure sensor, an excessively high exhaust gas recirculation temperature sensor value or a soaked cylinder intake port are recognized. These additional errors can be distinguished by this additional comparison.

An exhaust gas recirculation temperature is preferably determined and a check is carried out to determine whether a value for the temperature lies in a temperature value range, an exhaust gas recirculation temperature sensor error being detected if the value for the temperature lies outside the temperature value range and the operating state of the internal combustion engine being recognized depending on whether the Value for the temperature is within the temperature range or outside. In the case of a warm internal combustion engine, this simple temperature monitoring can already detect an error in an exhaust gas recirculation temperature sensor signal and distinguish it as a further operating state of the internal combustion engine. This also simplifies the monitoring function, since the monitoring function, when knowing whether a temperature error is present or not, leads to a clear error diagnosis.

• 1 schematisch eine Brennkraftmaschine,
• 2 schematisch ein Blockschaltbild einer Überwachung für die Brennkraftmaschine,
• 3 schematisch Schritte in einem Verfahren.

Further advantageous configurations result from the following description and the drawing. In the drawing shows

• 1 schematically an internal combustion engine,
• 2 schematically a block diagram of a monitoring system for the internal combustion engine,
• 3 schematically steps in one process.

1 schematically shows an internal combustion engine 100 , It is a contraption 100 with a combustion chamber 102 , in the via a throttle valve 104 that are in an intake manifold 106 is arranged, an air mass flow for combustion in the combustion chamber 102 is feedable.

Exhaust gas from the combustion is via an exhaust gas recirculation valve 108 that in an exhaust gas recirculation path 110 is arranged for combustion in the combustion chamber 102 fed.

Through a pressure sensor 112 is a pressure in the intake manifold 106 measurable.

The internal combustion engine 100 comprises a control device 120 , which is designed, a method described below by detecting signals of the pressure sensor 112 and outputting control signals for the throttle valve 104 and the exhaust gas recirculation valve 108 perform.

The signals from the sensors mentioned can be sent directly from the control device 120 detected or received via a communication network, for example a controller area network. The control signals for the actuators mentioned can be sent directly from the control device 120 output to them or sent via the communication network, for example the controller area network. Communication or signal lines to and from the controller 120 are in 1 Not shown for clarity.

The control for opening and / or closing the throttle valve and the exhaust gas recirculation valve is preferably carried out for complete opening and / or closing. A monitoring function represented by the method works in an operating state of the internal combustion engine 100 with fully open exhaust gas recirculation valve 108 and fully closed throttle valve 104 particularly reliable. However, it cannot be ruled out that the opening and / or closing can also be incomplete.

Below is the air path through the throttle valve 104 , the intake manifold 106 , the exhaust gas recirculation valve 108 and the exhaust gas recirculation path 110 back to the intake manifold 106 as the air system of the internal combustion engine 100 designated. The air system of the internal combustion engine 100 can, as in 1 shown, also an exhaust gas recirculation cooler 114 or an exhaust gas recirculation venturi sensor 116 in the exhaust gas recirculation path 110 exhibit. The air system of the internal combustion engine can also have an exhaust gas turbocharger or compressor.

2 shows schematically a block diagram of a monitoring that realizes the monitoring function.

In the example there is a first threshold A as the lower threshold is less than a second threshold B used, which specifies an upper threshold value for a range in which the air system of the internal combustion engine 100 works normally. A value X for the intake manifold pressure is compared to the first threshold A and the second threshold B compared. If the value X within the range between the first threshold A and second threshold B lies, it is assumed that the air system of the internal combustion engine 100 works normally. Otherwise an error is recognized.

The procedure is described below with reference to 3 described.

The process comprises one step 302 opening the exhaust gas recirculation valve 108 the internal combustion engine 100 ,

The process comprises one step 304 closing the throttle valve 104 the internal combustion engine 100 ,

The process comprises one step 306 the detection of the value X for the intake manifold pressure of the internal combustion engine 100 with open exhaust gas recirculation valve 108 and closed throttle valve 104 ,

The process includes an optional step 308 determining the first threshold value A and / or the second threshold value B. As an alternative to this, they can also be read from a memory in which the threshold values are stored.

For example, the first threshold A or the second threshold B determined depending on a parameter that influences the intake manifold pressure. The calibration of the parameters can be done during the operation of the internal combustion engine 100 for example in an application.

For example, the first threshold A or the second threshold B depending on a speed of the internal combustion engine 100 can be determined as parameters.

In addition or as an alternative to this, the first threshold value A or the second threshold B can be determined or corrected depending on an ambient pressure.

Instead of calibrating the threshold values, a physical model can also be used. For this purpose, the two threshold values are not defined based on the intake manifold pressure, but rather as effective areas of the EGR feedback path 110 (incl. open exhaust gas recirculation valve 108 , Exhaust gas recirculation cooler 114 , and if available the EGR venturi 116 ). This includes the advantage that no or comparatively minimal corrections to the threshold values via engine speed, ambient pressure, etc. are necessary, since these dependencies are already implicit in the model.

For this, the mass flow into the internal combustion engine 100 calculated by a model. Since with the throttle valve closed ( 104 ) and open exhaust gas recirculation valve 108 this mass flow, neglecting the throttle valve leakage, corresponds to the mass flow through the exhaust gas recirculation path 110 this must also be the case. The pressure upstream of the exhaust gas recirculation path 110 , and thus also upstream of a turbine of the exhaust gas turbocharger, is approximately equal to the ambient pressure when the throttle valve is almost completely or completely closed. In this operating state, there is a steady state in which no gas flows through the turbine, since the gas is between the combustion chamber 102 and the exhaust gas recirculation path 110 circulated. Therefore, the pressure in the entire exhaust system and the turbine will equalize, in a steady state all pressures are then equal to the ambient pressure.

The temperature of the gas can be determined by a suitable temperature sensor or based on a temperature model as the temperature upstream of the exhaust gas recirculation cooler 114 , downstream of the exhaust gas recirculation cooler or in the intake manifold.

In the example, the following equations determine the relationship between the input parameters and reference area values (threshold values) by modeling as a throttle point.

mit

• p_pos Druck nach Abgasrückführpfad 110 mit effektivem Querschnitt A,
• p_pre Druck vor Abgasrückführpfad 110, im betrachteten Betrieb mit offenem Abgasrückführventil 108 und geschlossener Drosselklappe 104 gleich dem Umgebungsdruck.

A pressure ratio π across the exhaust gas recirculation path 110 (incl. open exhaust gas recirculation valve 108 , Exhaust gas recirculation cooler 114 and if available exhaust gas recirculation venturi tube 116 ) is given as $$\mathrm{\pi }=\text{p}\_\text{pos / p\_pre}$$

With

• p_pos pressure according to exhaust gas recirculation path 110 with an effective cross-section A .
• p_pre Pressure before exhaust gas recirculation path 110 , in the considered operation with open exhaust gas recirculation valve 108 and closed throttle valve 104 equal to the ambient pressure.

mit

• dm Massenstrom über den Abgasrückführpfad 110, der in diesem Betrieb mit geschlossener Drosselklappe 104 und geöffnetem Abgasrückführ-Ventil 108 näherungsweise gleich dem Massenstrom in die Brennkraftmaschine 100 ist
• R_gas Gaskonstante für Luft,
• TGastemperatur im Abgasrückführpfad 110,
• Ψ(π) Durchflussfunktion.

The effective area A over the exhaust gas recirculation path 110 is given as $$\text{A =}\text{dm*}\surd \left(\text{R\_gas * T}\right)/\left(\surd 2*\text{p\_pre *}\mathrm{\Psi }\left(\mathrm{\pi }\right)\right)$$

With

• dm mass flow over the exhaust gas recirculation path 110 that in this operation with the throttle valve closed 104 and open exhaust gas recirculation valve 108 approximately equal to the mass flow into the internal combustion engine 100 is
• R_gas gas constant for air,
• TGast temperature in the exhaust gas recirculation path 110 .
• Ψ (π) flow function.

mit

k

Isentropenexponent von Luft.

The flow function is indicated by $$\mathrm{\Psi }\left(\mathrm{\pi }\right)=\surd \left(1/\left(1-1/\text{k}\right)\right)*\surd \left(1-{\mathrm{\pi }}^{\wedge }\left(1-1/\text{k}\right)\right){\mathrm{\pi }}^{\wedge }\left(1/\text{k}\right)$$

With

k

Isentropic exponent of air.

The process comprises one step 310 comparing value X with the first threshold value A and the second threshold value B. The first threshold value A and the second threshold value B specify a tolerance range that characterizes an operating state in which the internal combustion engine 100 has no sooting.

The process comprises one step 312 the detection of an operating state of the internal combustion engine 100 , depending on whether the value X in a range of values between the first threshold A and the second threshold B or is outside this range.

Sooting the exhaust gas recirculation path 110 the internal combustion engine 100 , especially the exhaust gas recirculation cooler 114 or the exhaust gas recirculation venturi sensor 116 in the exhaust gas recirculation path 110 , is recognized when the first threshold A is undercut.

A sooting of the cylinder intake ports of the internal combustion engine 100 or increased leakage from a throttle valve 104 the internal combustion engine 100 is detected when the second threshold B is exceeded.

An electric throttle valve diagnosis of the internal combustion engine 100 can in addition to distinguishing between an operating state of the sooting of the cylinder intake ports and an operating state with an increased leakage at the throttle valve 104 be evaluated.

In an optional step 314 a feed-forward regulation for exhaust gas recirculation and / or an adjustment of the parameters for the Calculation of an EGR mass flow via the measured variables of the exhaust gas recirculation venturi tube 116 the internal combustion engine 100 depending on a result of a comparison of the intake manifold pressure with the first threshold A and the second threshold B carried out. As an alternative or in addition to this, a mass flow model of the internal combustion engine is adapted 100 depending on a result of a comparison of the intake manifold pressure with the first threshold A and the second threshold B ,

Alternatively or in addition, it can be provided in the crotch 312 an exhaust gas recirculation mass flow of the internal combustion engine 100 with an intake manifold mass flow of the internal combustion engine 100 in a comparison, and depending on the result of the comparison, a soaked exhaust gas recirculation venturi tube 116 to detect a defective EGR-Venturi pressure difference sensor, soiled cylinder intake ports or a defective exhaust gas recirculation temperature sensor.

Alternatively or in addition, it can be provided in the crotch 312 determine an exhaust gas recirculation temperature and check whether a value for the temperature lies in a temperature value range. In this case, an exhaust gas recirculation temperature sensor fault is detected if the temperature value is outside the temperature value range. In addition, the operating state of the internal combustion engine is recognized depending on whether the value for the temperature is within the temperature value range or outside.

The steps 302 to 314 are executed consecutively in the example. Other orders are also possible, whereby steps can be omitted.

1. 1) Überwachung mittels Vergleich der Luftmassenströme (Massenstrom in die Brennkraftmaschine verglichen mit Massenstrom berechnet durch Messgrößen am Abgasrückführ-Venturirohr 116):
   1. a) Luftmassenstrom im Saugrohr 106 größer als Massenstrom im Abgasrückführpfad 110.
   2. b) Luftmassenstrom im Saugrohr 106 gleich wie Massenstrom im Abgasrückführpfad 110
   3. c) Luftmassenstrom im Saugrohr 106 kleiner als Massenstrom im Abgasrückführpfad 110.
2. 2) Überwachung mittels Vergleich des Werts X des Saugrohrdrucks oder alternativ der berechneten effektiven Fläche des Abgasrückführpfads 110 mit erstem Schwellwert A und zweitem Schwellwert B:
   1. a) X größer oder gleich B
   2. b) X kleiner oder gleich A
   3. c) A < X < B

Overall, the monitoring function in the example provides monitoring depending on the mass flow, ie on air and possibly exhaust gas in the air system of the internal combustion engine 100 and depending on the pressure in the intake manifold 106 When using an exhaust gas recirculation venturi tube 116 differential pressure sensor, an absolute pressure sensor, an intake manifold pressure sensor and / or temperature sensor, the following cases are possible:

1. 1) Monitoring by means of a comparison of the air mass flows (mass flow into the internal combustion engine compared to mass flow calculated by means of measured variables on the exhaust gas recirculation venturi tube 116 ):
   1. a) Air mass flow in the intake manifold 106 greater than mass flow in the exhaust gas recirculation path 110 ,
   2. b) Air mass flow in the intake manifold 106 same as mass flow in the exhaust gas recirculation path 110
   3. c) Air mass flow in the intake manifold 106 smaller than mass flow in the exhaust gas recirculation path 110 ,
2. 2) Monitoring by comparing the value X the intake manifold pressure or, alternatively, the calculated effective area of the exhaust gas recirculation path 110 with the first threshold A and second threshold B :
   1. a) X greater or equal B
   2. b) X less than or equal to A
   3. c) A <X <B

1a, 2a:

Fehlerfall, der hier nicht betrachtet wurde, da durch andere Methoden einfach zu diagnostizieren, z. b. ein defekter Saugrohrdrucksensor,

1a, 2b:

versottetes Abgasrückführ-Venturirohr116

1a, 2c:

i) Saugrohrdifferenzdrucksensor zeigt zu niedrigen Wert, ii) Abgasrückführtemperatursensor zeigt zu niedrigen Wert

1b, 2a:

Fehlerfall, der hier nicht betrachtet wurde, eventuell Kombination aus mehreren Fehlern oder mit weiteren anderen Fehlern im System

1 b, 2b:

versotteter Abgasrückführkühler 114

1b, 2c:

System bezüglich der betrachteten Fehlerfälle in Ordnung

1c, 2a:

versottetes Saugrohr, insbesondere nahe dem Einlass in den Brennraum 102

1c, 2b:

Fehlerfall, der hier nicht betrachtet wurde, eventuell Kombination aus mehreren Fehlern oder mit weiteren anderen Fehlern im System

1c, 2c:

i) Saugrohrdifferenzdrucksensor zeigt zu hohen Wert, ii) Abgasrückführtemperatursensor zeigt zu hohen Wert

The following matrix shows the operating states of the internal combustion engine 100 distinguished:

1a, 2a:

Failure that was not considered here because it is easy to diagnose using other methods, e.g. a defective intake manifold pressure sensor,

1a, 2b:

mottled exhaust gas recirculation venturi tube 116

1a, 2c:

i) Intake manifold differential pressure sensor shows too low value, ii) Exhaust gas recirculation temperature sensor shows too low value

1b, 2a:

Failure that was not considered here, possibly a combination of several errors or with other errors in the system

1 b, 2b:

soiled exhaust gas recirculation cooler 114

1b, 2c:

System ok with regard to the considered error cases

1c, 2a:

mottled intake manifold, especially near the inlet to the combustion chamber 102

1c, 2b:

Failure that was not considered here, possibly a combination of several errors or with other errors in the system

1c, 2c:

i) Intake manifold differential pressure sensor shows too high value, ii) Exhaust gas recirculation temperature sensor shows too high value

In the cases 1a . 2c and 1c . 2c If the exhaust gas recirculation temperature sensor error is detected, a distinction is also made between sub-cases i) and ii).

QUOTES INCLUDE IN THE DESCRIPTION

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

Patent literature cited

• DE 102008041804 A1 [0002, 0003]
• DE 102011100585 [0004]

Claims (13)

Method, characterized by opening (302) an exhaust gas recirculation valve (108) of an internal combustion engine (100), closing (304) a throttle valve (104) of the internal combustion engine (100), detecting (306) a value (X) for an intake manifold pressure of the internal combustion engine (100 ) with the exhaust gas recirculation valve (108) open and the throttle valve (104) closed, comparing (310) a value (X) with a first threshold value (A) and a second threshold value (B) which is greater than the first threshold value (A) (312) an operating state of the internal combustion engine (100), depending on whether the value (X) lies in a value range between the first threshold value (A) and the second threshold value (B) or outside this range. Procedure according to Claim 1 , characterized in that the first threshold value (A) or the second threshold value (B) is determined depending on a parameter that influences the intake manifold pressure. Method according to one of the preceding claims, characterized in that the first threshold value (A) or the second threshold value (B) is determined (308) as a function of a speed of the internal combustion engine (100). Method according to one of the preceding claims, characterized in that the first threshold value (A) or the second threshold value (B) is determined or corrected (308) depending on an ambient pressure. Method according to one of the preceding claims, characterized in that the first threshold value (A) and the second threshold value (B) specify a tolerance range which characterizes an operating state in which the internal combustion engine (100) has no sooting. Method according to one of the preceding claims, characterized in that soiling of an exhaust gas recirculation path (110) of the internal combustion engine (100), in particular an exhaust gas recirculation cooler (114) or an exhaust gas recirculation venturi sensor (116) in the exhaust gas recirculation path (110), is detected (312 ) when the first threshold (A) is undershot. Method according to one of the preceding claims, characterized in that a sooting of a cylinder inlet port of the internal combustion engine (100) or an increased leakage at a throttle valve (104) of the internal combustion engine (100) is detected (312) when the second threshold value (B) is exceeded , Procedure according to Claim 7 , characterized in that an air mass flow of the internal combustion engine (100) or an electrical throttle valve diagnosis of the internal combustion engine (100) is evaluated to distinguish between an operating state of the sooting of the intake manifold (106) and an operating state with the leak on the throttle valve (104). Method according to one of the preceding claims, characterized by adapting (314) a feed-forward control for exhaust gas recirculation of the internal combustion engine (100) and / or adapting parameters for calculating an EGR mass flow via a measured variable of an EGR Venturi tube depending on one Result of a comparison of the intake manifold pressure with the first threshold value (A) and the second threshold value (B), or adaptation (314) of a mass flow model of the internal combustion engine (100) depending on a result of a comparison of the intake manifold pressure with the first threshold value (A) and the second Threshold (B). Method according to one of the preceding claims, characterized in that an exhaust gas recirculation mass flow of the internal combustion engine (100) is compared in a comparison with a mass flow into the internal combustion engine (100) and, depending on the result of the comparison, a soaked exhaust gas recirculation venturi tube (116), a soaked one Venturi differential pressure sensor, an excessively high exhaust gas recirculation temperature sensor value or a soaked cylinder intake port is detected (312). Method according to one of the preceding claims, characterized in that an exhaust gas recirculation temperature is determined and a check is carried out to determine whether a value for the temperature lies in a temperature value range, an exhaust gas recirculation temperature sensor error being detected (312) if the value for the temperature lies outside the temperature value range and wherein the operating state of the internal combustion engine is recognized (312) depending on whether the value for the temperature lies within the temperature value range or outside. Method according to one of the preceding claims, characterized in that at least one of the threshold values is determined as the effective area (A) of the exhaust gas recirculation path (110), in particular as a function of a mass flow (dm) via the exhaust gas recirculation path (110), a gas constant for air (R_gas ), a gas temperature (T) upstream of the throttle valve (104) in the exhaust gas recirculation path (110), and a flow function (Ψ (π)) is determined. Device (100) characterized by a combustion chamber (102) in which a throttle valve (104) is arranged in an intake manifold (106), An air mass flow for combustion in the combustion chamber (102) can be supplied, whereby exhaust gas from the combustion can be supplied for combustion in the combustion chamber (102) via an exhaust gas recirculation valve (108), which is arranged in an exhaust gas recirculation path (110), whereby a pressure sensor ( 112), a pressure in the intake manifold (106) can be measured, and wherein a control device (120) is designed, the method according to one of the Claims 1 to 11 by detecting signals from the pressure sensor (112) and outputting control signals for the throttle valve (104) and the exhaust gas recirculation valve (108).

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