Leak diagnosis for intake devices

Abstract

The invention relates to a vehicle drive device having an internal combustion engine, an air guiding device, an exhaust device and a diagnostic unit for identifying a leak of the air guiding device of the internal combustion engine, wherein the diagnostic unit is designed to carry out a method for diagnosing a leak of the internal combustion engine, said method having at least the following method steps: determining a mass flow of the air guiding device, determining a leak mass flow.

Description

Technical Field

[0001] The present invention relates to a method for diagnosing leaks in the intake system of an internal combustion engine and a diagnostic unit for performing such a method, and to a vehicle drive system having an internal combustion engine, an intake system, an exhaust system and such a diagnostic unit. Background Technology

[0002] Occasionally, during the normal operation of known vehicle drive systems with internal combustion engines, intake devices, and exhaust devices, the fresh air guiding device and / or intake device may become unsealed, and the location of the unsealing cannot be accurately defined in the fresh air guiding device and / or intake device.

[0003] Known solutions offer a variety of general diagnostics for air systems. However, this makes it possible to diagnose only whether a leak exists at any one location within the air guide. This is achieved, for example, by considering the value of λ in US 2010 / 236218 A. Summary of the Invention

[0004] In this context, the objective of this invention is to improve the leak diagnosis in the intake system of an internal combustion engine of a motor vehicle.

[0005] Therefore, the present invention proposes a method for diagnosing leaks in internal combustion engines, the method comprising at least the following steps:

[0006] - Determine the mass flow rate of the air guiding device in an internal combustion engine.

[0007] - Establish a mass flow balance based on the calculated mass flow rate.

[0008] - Determine the leakage mass flow rate based on the established mass flow balance.

[0009] - The location and / or size of the leak are determined based on the determined leakage mass flow rate.

[0010] - Determine the overpressure leakage mass flow rate, and determine the characteristic values ​​of the overpressure parameters based on the determined overpressure leakage mass flow rate.

[0011] - Determine the negative pressure leakage mass flow rate, and determine the negative pressure parameter characteristic values ​​based on the determined negative pressure leakage mass flow rate.

[0012] - The location of the leak is determined by the ratio between the determined overpressure parameter characteristic value and the determined negative pressure parameter characteristic value.

[0013] The present invention also proposes a diagnostic unit for identifying leaks in the air guiding device of an internal combustion engine, wherein the diagnostic unit is designed to perform the method described in accordance with the present invention.

[0014] The present invention also proposes a vehicle drive device having an internal combustion engine, an air guiding device, and an exhaust device, wherein the vehicle drive device has the diagnostic unit described in the present invention.

[0015] According to one aspect, a method for diagnosing leaks in the air guiding device (especially the intake device) of an internal combustion engine (especially a motor vehicle) is disclosed. The method comprises at least one of the following method steps:

[0016] (i) Determine the mass flow rate of the air duct (especially the air collector of the intake system) (especially all conventionally configured). That is, in particular, determine all mass flow rates flowing into and out of the air duct (especially the intake system) during normal operation of the internal combustion engine. In other words, conventional mass flow rates should now be understood, in particular, as each mass flow rate in the air duct that can be configured to drive the vehicle during normal operation of the vehicle drive system—as opposed to unconventional or unconfigured leakage mass flow rates.

[0017] (ii) Establish a mass flow balance based on the obtained mass flow rate. The establishment of the mass flow balance is described in detail, especially with reference to the embodiments.

[0018] (iii) Determine the leakage mass flow rate based on the established mass flow rate balance. The determination of the leakage mass flow rate is described in detail, especially with reference to the embodiments.

[0019] Determining the leakage mass flow rate based on the established mass flow rate balance enables targeted and precise measures to compensate for the leakage mass flow rate, even during normal operation of the internal combustion engine. Compensating for leakage mass flow rate can be understood as measures to mitigate the undesirable effects of leakage mass flow rate and / or measures to eliminate leakage mass flow rate.

[0020] Currently, leakage can be understood in particular as holes (i.e., leaks) in components of air guiding devices, especially air intake devices.

[0021] The air guiding device particularly includes a boost air guiding device, a boost air cooler, and / or an intake device with an interface to the intake valve. Especially in the fresh air guiding device, a compressor for an exhaust turbocharger and / or a throttle valve for desired metering of fresh air entering the air collector are provided.

[0022] Currently, determining leakage mass flow rate should be understood in particular as identifying leakage mass flow rate, and especially as identifying the existence of leakage mass flow rate. Additionally, this should be understood in particular as providing a more detailed description of the leakage mass flow rate based on its location, size, and / or flow direction, especially in the sense of distinguishing it from other possible locations, sizes, and / or flow directions of leakage mass flow rate.

[0023] According to another aspect, a diagnostic unit is disclosed, which is particularly configured as a system component of the engine control unit of a vehicle drive system. This diagnostic unit is used to identify leaks in the air intake system (especially the intake system) of an internal combustion engine (particularly in motor vehicles). This diagnostic unit is designed to perform a method according to an embodiment of the invention.

[0024] According to another aspect, a vehicle drive system is disclosed, the vehicle drive system having an intake device, an internal combustion engine, and an exhaust device. This vehicle drive system has a diagnostic unit according to an embodiment of the invention.

[0025] According to one embodiment, the vehicle drive system has an exhaust gas recirculation line (AGR line) designed to connect the exhaust system and the intake system in a guided exhaust manner.

[0026] For vehicle drive systems incorporating exhaust gas recirculation (AGR), this invention, and the associated feasibility of diagnosing leaks during normal operation of the internal combustion engine, is particularly advantageous. This is because the exhaust gas guided along with it can reach a significantly higher temperature than the compressed but cooled supplied fresh air, even though the recirculated exhaust gas flows through the AGR cooler.

[0027] The intake system—the AGR line enters the intake system—is often constructed of plastic materials. Therefore, under very unfavorable operating conditions, such as high ambient temperatures and high AGR mass flow rates at the engine's operating point, leaks can occur, for example, due to the recirculated exhaust gas introducing heat into the plastic air collector, especially when there is already some soot on the walls under the greatest load.

[0028] This invention is based in particular on the following considerations: known leak diagnosis methods cannot pinpoint the specific fault mode of a leak in the intake system, and in particular, lack the precision to distinguish the location of other leaks. Furthermore, known leak diagnosis methods cannot reliably identify faults during normal operation.

[0029] In addition, the present invention is based in particular on the consideration that such differentiated diagnosis can serve as the basis for targeted alternative responses to leaks, even while the vehicle is already in operation.

[0030] The present invention is now particularly based on the concept of continuously determining the leakage mass flow rate by means of the conventional mass flow rate at the intake device according to embodiments. In the unsealed case, the basic leakage mass flow rate can be determined in the corresponding mass flow rate balance.

[0031] The present invention can be used, in particular—but not only—in turbocharged internal combustion engines, which have a throttle valve or other suitable throttling mechanism at the inlet of the fresh air guide device to the intake device and may be equipped with exhaust gas recirculation (AGR).

[0032] There are inflow and outflow (fluid) mass flow rates into the intake device, and the sum of the inflow and outflow (fluid) mass flow rates is balanced under ideal conditions (i.e., no balance error and / or actual leakage mass flow rate):

[0033] The mass flow rate enters through the throttle valve and, if necessary, through the AGR path. The mass flow rate exits into the combustion chamber of the internal combustion engine cylinder.

[0034] In the event of a leak, the leak mass flow rate is added, which is the inflow or outflow mass flow rate depending on the gas pressure ratio between the internal pressure of the air intake device and the ambient pressure.

[0035] The present invention is particularly based on the concept of considering the relationship between the pressure in the air intake device and the ambient air pressure.

[0036] Here, according to one implementation method, a distinction is made between the operating range where the boost pressure is higher than the ambient pressure and the operating range where the boost pressure is lower than the ambient pressure.

[0037] In the case of overpressure in the intake system, the leakage mass flow rate is defined as the mass flow rate flowing out of the intake system. In the case of negative pressure in the intake system, the leakage mass flow rate is the mass flow rate flowing in.

[0038] Only leaks with a root cause (i.e., the hole that causes the leak) in the intake device can be described by this consideration (especially the coupling consideration of the leak ratio under overpressure and negative pressure conditions).

[0039] Leaks at other locations are unrelated to assumptions made based on the implementation method, such as the coupling of mass flow rate and boost pressure. This assumption is described in particular with reference to the embodiments.

[0040] Compared to the typical errors present in air system sensors and the resulting model inaccuracies of known leak diagnosis methods, the present invention achieves the required distinguishing accuracy to differentiate between typical system tolerances and sensor errors and failure modes of leaks in the intake system.

[0041] The balanced leakage mass flow rate depends on the corresponding gas state (pressure, temperature) in the intake system. This operating point dependence can be eliminated by calculating characteristic parameters. For this purpose, according to one implementation, the leakage can be calculated back to the throttle cross-section or throttle diameter using a flow equation (throttle equation).

[0042] If the results for the leakage cross-sections in the overpressure and negative pressure ranges are of similar magnitude, such that the two results are correlated with the assumptions made in the same way, then a reliable diagnosis of leakage in the intake system can be obtained according to one implementation. If valid calculation results exist in both the overpressure and negative pressure ranges, then very small leaks in the area between the intake system and the AGR system have been specifically detected.

[0043] Correspondingly, according to one implementation method, a specific alternative reaction can be introduced (to compensate for and / or eliminate leaked mass flow during normal operation or workshop stays) to ensure reliable and environmentally friendly vehicle operation.

[0044] If the leakage continues to increase despite the adoption of alternative measures, this is identified through diagnostics according to one implementation method, and a more stringent alternative measure is introduced. In the case of performing the original alternative measure during normal driving operation, further driving can be abandoned, for example, before inspection in the workshop.

[0045] According to one embodiment, the present invention is implemented as a diagnostic unit (i.e., diagnostic function) in an engine controller.

[0046] According to one embodiment, the method additionally includes the step of determining the location and / or size (especially the diameter) of the leak based on the determined leakage mass flow rate. This allows for more accurate demarcation, determining what measures need to be taken to compensate for the leakage mass flow rate during internal combustion engine operation and to what extent.

[0047] According to one implementation, the leakage mass flow rate is determined during normal operation of the internal combustion engine. This allows for measures to be taken directly after the initial occurrence of the leakage mass flow rate to compensate for it.

[0048] According to one embodiment, the method additionally includes the following method steps:

[0049] - Determine the overpressure leakage mass flow rate and, based on the determined overpressure leakage mass flow rate, determine the overpressure parameter characteristic values, especially for the first operating state (e.g., normal vehicle operation), and / or

[0050] - Determine the negative pressure leakage mass flow rate and, based on the determined negative pressure leakage mass flow rate, determine the negative pressure parameter characteristic values, especially for the second operating state (e.g., during the regeneration operation of a storage catalyst or particulate filter).

[0051] - The location of the leak is determined based on the ratio between the determined overpressure parameter characteristic value and the determined negative pressure parameter characteristic value.

[0052] The ratio between the determined overpressure parameter characteristic value and the determined negative pressure parameter characteristic value can be used as an indicator of the location of the leak. In particular, the diameter or area of ​​the leak can be considered as a parameter characteristic value of the leak.

[0053] For example, suppose that if the two parameter characteristic values ​​are approximately the same size before adjustment, that is, the ratio between them is approximately 1, then the leak exists in the region where the intake device establishes mass flow balance. If the ratio deviates significantly from 1, then it is assumed, for example, that the leak exists in another region of the intake device.

[0054] However, the ratio between the overpressure parameter characteristic value and the negative pressure parameter characteristic value can also be obtained by means of threshold observation, which is aimed at a predetermined threshold for the relevant leak, such as determining from which leak diameter or leak area the calculation results by means of the engine control device are generally interpreted as a leak, rather than as a measurement error, detection dispersion or similar situation.

[0055] If the determined overpressure parameter characteristic value and the determined negative pressure parameter characteristic value are greater than the threshold, then the intake device (i.e., especially after the throttle valve) can be identified as the location of the leak.

[0056] If only one of the determined overpressure parameter characteristic value and the determined negative pressure parameter characteristic value is greater than the threshold, then the pressurized air guiding device can be identified as the location of the leak.

[0057] According to one implementation, the size (especially the diameter) of the leak is determined based on one or more determined leakage mass flow rates. This also allows for a better definition of suitable measures to compensate for the leakage mass flow rate.

[0058] According to one embodiment, an alternative response to the leaking mass flow rate, particularly for compensating for or eliminating the leak, is determined based on the location, size, and / or flow direction of the determined leaking mass flow rate. In this way, the internal combustion engine can continue to operate even with the presence of a leak, especially even with acceptable emissions, if necessary.

[0059] According to one embodiment, the leakage mass flow rate is determined based on the ambient pressure of the intake device. This allows for the description of the magnitude and / or flow direction of the leakage mass flow rate.

[0060] According to one embodiment, the mass flow rate, particularly the conventional mass flow rate and leakage mass flow rate of the intake device, is determined based on at least one pressure of the air, mixture, or exhaust gas, especially in the intake device, and / or on ambient pressure. Additionally or alternatively, the mass flow rate is determined based on at least one temperature of the air, mixture, or exhaust gas, especially in the intake device. Additionally or alternatively, the mass flow rate is determined based on the interface cross-section, particularly the inlet or outlet cross-section entering or leaving the intake device (especially entering or leaving the air collector).

[0061] Therefore, mass flow balance can be achieved by establishing the relationship between the fluid flow through the nozzle, especially the throttling equation. Attached Figure Description

[0062] Further advantages and applicability of the present invention will be apparent from the following description relating to the accompanying drawings.

[0063] Figure 1 A vehicle drive device having a diagnostic unit according to an exemplary embodiment of the present invention is shown.

[0064] Figure 2 Shown from Figure 1 The mass flow rate at the air intake of the air guide device of the vehicle drive equipment, by taking into account the mass flow rate, enables the execution of a method according to an exemplary embodiment of the present invention. Detailed Implementation

[0065] Figure 1 A vehicle drive system 1 with an internal combustion engine 2 is shown. In this embodiment, the internal combustion engine 2 is configured as a four-cylinder diesel engine. The internal combustion engine 2 is connected to an air intake device 4 to supply oxygen; and is connected to an exhaust device 6 to guide exhaust gas and purify exhaust gas if necessary.

[0066] The air guiding device 4 includes a boosted air guiding device 8, a boosted air cooler 10, a throttle valve 12, and an intake device 14.

[0067] The exhaust system 6 has an exhaust manifold 18 and an exhaust aftertreatment assembly 20 along the exhaust guide device 16. The exhaust aftertreatment assembly has at least one oxidation catalyst, but in particular has additional aftertreatment devices, such as at least one particulate filter and / or at least one SCR catalyst.

[0068] To increase the power of the internal combustion engine 2, a two-stage exhaust turbocharger 22 is provided in the boost air guide device 8 of the air guide device 4 and in the exhaust guide device 16 of the exhaust device 6. The compressor of the exhaust turbocharger 22 is located in the boost air guide device 8, and the turbine of the exhaust turbocharger 22 is located in the exhaust guide device 16. This embodiment illustrates an engine topology with two turbochargers arranged in series. Of course, the present invention and the exemplary embodiments described herein can also be applied in other engine topologies (e.g., those with a single turbocharger).

[0069] In this embodiment, the high-pressure compressor and high-pressure turbine of the exhaust turbocharger 22 are respectively bypassable by means of a switchable bypass configuration.

[0070] The air guide device 4 and the exhaust device 6 can be connected via a switchable high-pressure AGR line 24, allowing hot exhaust gas from the exhaust manifold 18 to be guided into the air collector 14 and mixed there with fresh air. In this embodiment, the exhaust gas in the AGR line 24 can be switched to pass through the AGR cooler and / or alongside the AGR cooler.

[0071] A hot-film air flow meter HFM for measuring air mass flow rate mHFM and a temperature sensor for measuring fresh air temperature T10 are installed at the fresh air inlet 7 of the pressurized air guiding device 8.

[0072] A pressure sensor is installed between the two compressors to measure the compressor pressure p12 in the booster air guiding device 8.

[0073] A temperature sensor for measuring the temperature T21 before the throttle valve in the fresh air guiding device is provided between the booster air cooler 10 and the throttle valve 12.

[0074] A pressure sensor for measuring the boost pressure p22 is provided in the air collector 14.

[0075] A temperature sensor is installed in AGR line 24 to measure the temperature T-nAGR of the AGR mixture entering the air collector 14.

[0076] A pressure sensor for measuring the turbine inlet pressure p31 is installed in the exhaust manifold 18.

[0077] A λ sensor is provided between the low-pressure turbine of the exhaust turbocharger 22 and the exhaust aftertreatment assembly 20 for measuring the composition of the mixture before the exhaust enters the exhaust aftertreatment assembly 20.

[0078] Additionally, the vehicle drive unit 1 has an engine control unit 30, which is designed to operate the vehicle drive unit 1 and all its components according to the operating requirements of the motor vehicle. The engine control unit 30 is also designed to take into account the measurements of all the sensors mentioned above to optimize the operation of the vehicle drive unit and its components, and, when necessary, to access its own common operating models, lookup tables, etc., using the detected and / or processed sensor values.

[0079] The engine control unit 30 has a diagnostic unit 32, which is designed to perform an exemplary method for diagnosing a leak 40 in the air guide device 4 of the vehicle drive equipment 1 and thereby determine the leak mass flow rate.

[0080] The following will be based on the Figure 2 The illustrations provide a detailed description of the implementation of this exemplary method with several variations.

[0081] Figure 2 The schematic diagram illustrates the typical mass flow rate at air collector 14: throttle mass flow rate entering the air collector. and AGR mass flow And the mass flow rate of the filling gas from the air collector into the cylinder. .

[0082] Additionally, mark any potential leaks in mass flow rate that need to be diagnosed or determined. Leakage mass flow rate without prior consideration of flow direction. Mark; Leakage mass flow rate The flow can proceed in either direction, depending on whether the ambient pressure p0 is higher or lower than the boost pressure p. 22 —Therefore, a double arrow is used to represent it.

[0083] By using Figure 2 The temperature value T in the air collector 14 is marked in the attached text. 22 Furthermore, the diagnostic unit 32, utilizing the operating model and lookup table stored in the engine control unit 30 (and, if necessary, combined with additional measurements from the aforementioned sensors), is designed to perform a method for diagnosing leaks 40 in the air guide device 4 and, in particular, the air collector 14.

[0084] Therefore, the conventional mass flow rate (throttle mass flow rate) of the intake device 4 is first determined for the air collector 14. AGR mass flow rate and filling mass flow rate ).

[0085] Subsequently, a mass flow balance is established using the diagnostic unit 30 based on the calculated mass flow rate. Here, the mass flow balance of the optimized sealing intake device is obtained as follows:

[0086]

[0087] For intake devices with unoptimized seals, this results in an initially undetermined leakage mass flow rate. The mass flow balance established is applicable to determining the leakage mass flow rate as follows:

[0088]

[0089] in, and

[0090] In this way, the leakage mass flow rate is determined based on the established mass flow rate balance during normal operation of the internal combustion engine. .

[0091] General throttling equations for fluid flow

[0092]

[0093] It can depend on the determined leakage mass flow rate Determine the parameters of the leak section 40, here being the diameter d. Leck .

[0094] d Leck The calculation is based on d Leck In a leak-free intake system, it equals zero, or at least almost exactly zero, taking into account smaller calculation errors.

[0095] In this exemplary method, the overpressure leakage mass flow rate (i.e., at the boost pressure p) is determined. 22 Within the operating range exceeding the ambient pressure p0, such as during normal operation, the negative pressure leakage mass flow rate (i.e., at the boost pressure p) is determined. 22 In operating ranges below ambient pressure p0, such as during regeneration of storage catalysts or particulate filters, the overpressure parameter characteristic values ​​(here, the overpressure leakage cross-section) are determined based on the determined overpressure leakage mass flow rate. The negative pressure parameter characteristic values ​​(here, the negative pressure leakage cross-section) are determined based on the determined negative pressure leakage mass flow rate.

[0096] Then, the location of the leakage section 40 is determined based on the ratio between the overpressure leakage cross section and the negative pressure leakage cross section.

[0097] If the two leakage cross sections (as a parameter characteristic value for leakage) are approximately the same size before the adjustment sign, that is, the ratio between them is approximately 1, then it is assumed that the leakage section 40 exists in the region of the air guiding device 4 where mass flow balance is established, which is in the air collector 14. If the ratio deviates significantly from 1, then it is assumed that the leakage section 40 exists in another region of the air guiding device 4.

[0098] This ratio can also be obtained indirectly, for example by comparing a predetermined threshold of the relevant leakage cross-section with both a defined overpressure leakage cross-section and a defined negative pressure leakage cross-section.

[0099] Here, it is necessary to consider that small errors in the calculation of the conventional mass flow rate using the engine control unit 30 may lead to an incorrect calculation of the leakage diameter d. Leck The error in the estimation. For example, we can consider A as follows: Leck Estimated value:

[0100] Considering mass flow error

[0101]

[0102] And assume p 22 >0 and p 22 The area error behavior is the same when <0, resulting in

[0103]

[0104] And thus obtain the average area

[0105]

[0106] And regarding the leakage diameter

[0107]

[0108] Obtain the average leakage diameter

[0109]

[0110] To calculate the leakage area A Leck This will be used to leak mass flow rate. Equation 2 is inserted into Equation 1:

[0111] (3)

[0112] in,

[0113]

[0114] R is the gas constant

[0115] κ is the adiabatic exponent.

[0116] For overpressure operating points with p22 > p0 (boost pressure greater than ambient pressure), in Equation 3, p vor (p 前 ) is equivalent to the boost pressure p 22 ; p nach (p 后 ) is equivalent to the ambient pressure p0. These two values are provided to the engine control device 30 as sensor measurement values and thus to the diagnostic unit 32. Additionally, T vor (T 前 ) is equivalent to the temperature T in the intake device 14 22 . The engine control device 30 can obtain T 22 from the operating model and / or a look-up table. Taking into account the measurement values of the existing pressure sensors, the AGR mass flow can be obtained from the operating model. The throttle mass flow can be obtained from the value of the air mass sensor HFM through dynamic adaptation. Taking into account the measured pressure values and the measured engine speed N, the mass flow entering the combustion chamber can be obtained from the operating model. The required calculations are performed by the engine control device 30 and / or the diagnostic unit 32 respectively.

[0117] For negative pressure operating points with p 22 < p0 (boost pressure less than ambient pressure), in Equation 3, p nach (p 后 ) is equivalent to the boost pressure p 22 ; p vor (p 前 ) is equivalent to the ambient pressure p0. These two values are provided to the engine control device 30 as sensor measurement values and thus to the diagnostic unit 32. Additionally, the ambient temperature value can be approximately used for T vor (T 前 ), or for example, a combination of the weighted ambient temperature and the engine temperature - especially with the aid of a pre-filled characteristic curve family - can be used for T vor , the aim being to accurately reflect the true temperature depending on the operating point. The engine control device 30 can obtain T 22 from the operating model and / or a look-up table. Taking into account the measurement values of the existing pressure sensors, the AGR mass flow can be obtained from the operating model. The throttle mass flow can be obtained from the value of the air mass sensor HFM through dynamic adaptation. Taking into account the measured pressure values and the measured engine speed N, the mass flow entering the combustion chamber can be obtained from the operating model. The required calculations are performed by the engine control device 30 and / or the diagnostic unit 32 respectively.

[0118] The condition that applies to both overpressure and negative pressure operating points is: If for A Leck If a value is obtained that deviates only slightly from zero, it is still assumed that the air guide device 4 is at least substantially sealed. In this case, the value is typically not equal to zero only due to model tolerances and / or sensor tolerances. Therefore, the obtained value—depending on the application—is at most approximately 10 to 15 mm. 2 A Leck The value of A leads to a diagnosis of a "sealed system". Therefore, in general, the calculated A is significantly smaller than the expected leakage in a failure condition. Leck The value yields a diagnosis of a "sealed system." The limits of discriminative precision for the assumptions used in the diagnosis depend particularly on existing system tolerances.

[0119] If you get a higher A Leck The value of is then assumed to be 40 in the sense of the previously mentioned, predetermined threshold (similarly for the leakage diameter if necessary).

[0120] If A is obtained at the overpressure operating point and the negative pressure operating point Leck The values ​​correspond to some extent—that is, if the size ratio between them is particularly between 0.75 and 1.25, for example between 0.9 and 1.1—then the diagnosis performed also allows for the following statement:

[0121] The diagnosed leak 40 is located at the component of the air guide device 4 that establishes mass flow balance, here at the air collector 14.

[0122] Assuming that the leak 40 there has at least substantially the same characteristics as A Leck The size corresponding to the average of the two values ​​obtained.

[0123] Appropriate measures (i.e., alternative responses) can be taken based on the location and size of the leak 40 diagnosed in this way to compensate for and / or eliminate the leak 40—which is already in normal operation and / or in a workshop stop where necessary.

[0124] List of reference numerals

[0125] 1. Vehicle drive system

[0126] 2. Internal Combustion Engine

[0127] 4. Air guiding device

[0128] 6. Exhaust system

[0129] 8. Pressurized air guiding device

[0130] 10. Boost Air Cooler

[0131] 12 Throttle valves

[0132] 14. Air intake device

[0133] 16. Exhaust guiding device

[0134] 20 Exhaust Aftertreatment Components

[0135] 22 Exhaust Turbocharger

[0136] 24 High-voltage AGR lines

[0137] 30 Engine control unit

[0138] 32 Diagnostic Units

[0139] 40. Leakage Department, or Leakage

[0140] A Leck Leakage area

[0141] d Leck diameter of the leak

[0142] HFM hot film air flow meter

[0143] AGR mass flow

[0144] Fill mass flow rate

[0145] Leakage mass flow

[0146] Throttle mass flow rate and one

[0147] p0 Environmental pressure

[0148] p 12 Compressor pressure

[0149] p 22 Boost pressure

[0150] p 31 Turbine inlet pressure

[0151] T 10 Fresh air temperature

[0152] T 21 Throttle body temperature

[0153] T 22 Air collector temperature

[0154] T-nAGR AGR mixture temperature

[0155] λ Fuel-air ratio

Claims

1. A method for diagnosing a leak (40) in an internal combustion engine (2), the method comprising at least the following method steps: - Determine the mass flow rate of the air guiding device (4) of the internal combustion engine. , , ), - Establish a mass flow balance based on the calculated mass flow rate. - Determine the leakage mass flow rate based on the established mass flow balance ( ), - The location and / or size of the leak are determined based on the determined leakage mass flow rate (A). Leck d Leck ), - Determine the overpressure leakage mass flow rate ( ), and the overpressure parameter characteristic value (A) is determined based on the determined overpressure leakage mass flow rate. Leck,ü d Leck,ü ),and - Determine the negative pressure leakage mass flow rate ( ), and the negative pressure parameter characteristic value (A) is determined based on the determined negative pressure leakage mass flow rate. Leck,U d Leck,U ), - The location of the leak is determined by the ratio between the determined overpressure parameter characteristic value and the determined negative pressure parameter characteristic value.

2. The method according to claim 1, characterized in that, Determine the leakage mass flow rate during the normal operation of the internal combustion engine.

3. The method according to claim 1 or 2, characterized in that, The size of the leak is determined based on one or more determined leakage mass flow rates.

4. The method according to claim 1 or 2, characterized in that, The alternative response to the leaking mass flow rate is determined based on the location, size, and / or flow direction of the identified leaking mass flow rate.

5. The method according to claim 1 or 2, characterized in that, The leakage mass flow rate is determined based on the ambient pressure (p0) of the intake device.

6. The method according to claim 1 or 2, characterized in that, Depends on at least one pressure (p0, p) 12 p 22 p 31 ), at least one temperature (T) 10 T 21 T 22 The mass flow rate can be obtained from the cross-section of the interface and / or the interface.

7. The method according to claim 1, characterized in that, The mass flow rate mentioned is the conventional mass flow rate.

8. The method according to claim 6, characterized in that, The mass flow rate mentioned is the conventional mass flow rate.

9. A diagnostic unit for identifying leaks (40) in the air guiding device (4) of an internal combustion engine (2), characterized in that, The diagnostic unit is designed to perform the method according to any one of claims 1 to 8.

10. A vehicle drive system (1), comprising an internal combustion engine (2), an air intake device (4), and an exhaust device (6), characterized in that, The vehicle drive system has a diagnostic unit (30) as described in claim 9.

11. The vehicle drive device according to claim 10, characterized in that, The vehicle drive system has an exhaust recirculation line (24) designed to connect the exhaust device to the intake device in a way that guides the exhaust.

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