JP5246298B2 - Intake leakage diagnosis device for internal combustion engine - Google Patents

Description

  The present invention relates to an intake air leakage diagnosis device for an internal combustion engine.

  Patent Document 1 discloses a first cylinder intake air amount calculated based on a measurement result of an air flow sensor and a detection result of a sensor other than an air flow sensor that detects a value of a parameter representing an operating state of the internal combustion engine. When the difference from the calculated second cylinder intake air amount (air amount difference) is large, the first cylinder increases as the pressure difference between the pressure in the intake passage on the downstream side of the throttle valve and the pressure of the outside air increases. An abnormality detection device is disclosed that determines that there is a leak in the intake system when it is determined that the difference between the internal intake air amount and the second in-cylinder intake air amount (air amount difference) tends to increase. .

  Further, in Patent Document 2, when the oxygen concentration in the engine room is equal to or lower than the first predetermined concentration, EGR gas leaks from the intake system or the exhaust system connected to the engine disposed in the engine room. EGR gas recirculation is stopped by the EGR device that recirculates part of the exhaust gas from the exhaust system to the intake system as EGR gas, and after a predetermined time has elapsed since the EGR gas recirculation was stopped, oxygen in the engine room When the concentration is equal to or higher than the second predetermined concentration, it is determined that an EGR gas leak has occurred from the intake system, and when the concentration is lower than the second predetermined concentration, it is determined that an EGR gas leak has occurred from the exhaust system. A gas leak detection device is disclosed.

JP 2009-103114 A JP 2009-209664 A

  However, in a state where a part of the exhaust gas is recirculated to the intake passage, even if the intake air leaks from the intake passage, the first cylinder intake air amount based on the air flow sensor and the operating state of the internal combustion engine are represented. Since the difference from the second cylinder intake air amount based on the parameters (air amount difference) is small, the abnormality detection device as disclosed in Patent Document 1 leaks into the intake system in consideration of component variations and sensor variations. It may not be possible to accurately determine whether or not there is.

  In addition, when a supercharger is provided and feedback control of the supercharging pressure is performed so that the actual supercharging pressure becomes the target supercharging pressure, the supercharging pressure can be obtained even when intake air leaks from the intake passage. Since the supercharging pressure is restored by the feedback control, the difference between the first cylinder intake air amount and the second cylinder intake air amount is unlikely to occur, and there is a possibility that it cannot be determined whether or not there is a leak in the intake system. is there.

  Patent Document 2 determines whether an EGR gas leak has occurred from the intake system or the exhaust system based on the oxygen concentration in the engine room, and is upstream of the portion where the EGR gas merges in the intake system. When the intake air leaks on the side, there is a problem that the leakage of gas (intake air) from the intake system cannot be detected.

  In view of this, an intake air leakage diagnosis device for an internal combustion engine according to the present invention performs a primary determination of whether or not there is an intake air leak from the intake passage based on the control state of the turbocharger, and the intake air leakage from the intake passage by the primary determination. If the exhaust gas recirculation amount that is set according to the operating state is reduced, the intake air amount detected on the upstream side of the turbocharger compressor and the operation of the internal combustion engine are determined. Based on the estimated intake air amount estimated from the state, a secondary determination of the presence or absence of intake air leakage from the intake passage is performed, and as a result of the secondary determination, based on the intake air amount and the estimated intake air amount, the intake air passage It is characterized by determining that the intake air is leaking from.

  According to the present invention, when intake air leakage is suspected by the primary determination, the estimated intake air amount estimated from the operating state of the internal combustion engine and the upstream side of the compressor are detected with the EGR reduced more than usual. Since the secondary determination using the intake air amount is performed, EGR is not reduced every time diagnosis is performed, and it is possible to accurately determine intake air leakage from the intake passage while suppressing deterioration of fuel consumption. It becomes possible.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed typically the whole structure of the diesel engine to which this invention is applied. Explanatory drawing which showed the correlation of exhaust pressure and a torque in contrast with the case where intake air is not leaking from an intake passage, and the case where predetermined amount of intake air is leaking from an intake passage. The correlation between the boost pressure and the intake air amount when the exhaust gas recirculation amount is less than or equal to a predetermined value, the case where the intake air is not leaking from the intake passage, the case where the predetermined amount Q of intake air is leaking from the intake passage, Explanatory drawing shown in contrast with. The flowchart which shows the flow of control regarding the intake air leakage diagnosis which concerns on this invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an overall configuration of a diesel engine 1 to which the present invention is applied. A diesel engine 1 as an internal combustion engine performs exhaust gas recirculation (EGR), and an EGR passage 4 is provided between an exhaust passage 2 and a collector portion 3 a of the intake passage 3. An EGR control valve 6 and an EGR cooler 7 are interposed in the EGR passage 4. The opening degree of the EGR control valve 6 is controlled by the control unit 5 so as to obtain a predetermined EGR rate corresponding to the operating conditions. For example, the EGR rate becomes maximum in the low speed and low load range, and the EGR rate decreases as the engine speed and load increase. That is, the EGR passage 4 and the EGR control valve 6 controlled by the control unit 5 constitute exhaust recirculation means for recirculating a part of the exhaust gas to the intake passage 3.

  A fuel injection valve 9 and a glow plug 10 are disposed in the combustion chamber 8 of the diesel engine 1.

  The diesel engine 1 has a turbocharger 21 that is provided with a turbine 22 and a compressor 23 on the same axis. The turbine 22 is located on the downstream side of the EGR passage 4 branch point of the exhaust passage 2 and has a variable displacement type structure including a variable nozzle 24 as a capacity adjusting means at the scroll inlet of the turbine 22. That is, when the opening of the variable nozzle 24 is small, the characteristics of the small capacity are suitable for conditions with a small exhaust flow rate such as a low speed region, and when the opening of the variable nozzle 24 is large, the characteristic is as in the high speed region. Large capacity characteristics suitable for conditions with a large exhaust flow rate. The variable nozzle 24 is driven by a diaphragm actuator 25 that responds to a control pressure (control negative pressure).

  On the upstream side of the turbine 22 interposed in the exhaust passage 2, an exhaust pressure sensor 31 is provided as exhaust pressure detection means for detecting an actual exhaust pressure that is a pressure in the exhaust passage 2 upstream of the turbine 22. Yes.

  An air flow meter 35 as an intake air amount detecting means for detecting the actual intake air amount Qair is disposed on the upstream side of the compressor 23 interposed in the intake passage 3, and an air cleaner 36 is positioned further upstream. On the inlet side of the air cleaner 36, an atmospheric pressure sensor 37 for detecting an outside air pressure, that is, an atmospheric pressure, and an outside air temperature sensor 38 for detecting an outside air temperature are arranged. An intercooler 39 that cools the supercharged high-temperature intake air is provided between the compressor 23 and the collector unit 3 a located on the downstream side of the compressor 23.

  Further, a throttle valve 40 that restricts the intake air amount is interposed on the inlet side of the collector portion 3 a of the intake passage 3. The throttle valve 40 is opened and closed by a control signal from the control unit 5.

  In addition, a supercharging pressure sensor 41 is provided in the collector portion 3 a of the intake passage 3 as supercharging pressure detection means for detecting a supercharging pressure that is a pressure in the intake passage 3 on the downstream side of the compressor 23.

  In addition to the above sensors, the control unit 5 that controls the injection amount and injection timing of the fuel injection valve 14, the opening degree of the EGR control valve 6, the opening degree of the variable nozzle 24, etc. Detection signals of sensors such as an accelerator opening sensor 46 to detect, a rotation speed sensor 47 to detect the engine speed, and a water temperature sensor 48 to detect the cooling water temperature are input.

  In the control unit 5, feedback control of the supercharging pressure is performed so that the detected value of the supercharging pressure sensor 41, which is the actual supercharging pressure, becomes the target supercharging pressure calculated according to the operating state of the diesel engine 1. ing. The target boost pressure is calculated, for example, by searching a predetermined map from the accelerator opening and the engine speed. In the supercharging pressure feedback control, the detected value of the supercharging pressure sensor 41 is set to the target supercharging pressure based on the basic control amount for the actuator 25 calculated by searching a predetermined map from the fuel injection amount and the engine speed. The control unit 5 outputs the sum of the boost pressure feedback correction amount calculated as described above to the actuator 25 as a command value.

  The intake air amount (estimated intake air amount Qin1) of the diesel engine 1 when there is no intake air leakage from the intake passage 3 is estimated from the operating state of the diesel engine 1. In the present embodiment, the boost pressure sensor 41 By calculating a predetermined map from the detected supercharging pressure and the engine speed, it is calculated in a form including the exhaust gas recirculation amount. The estimated intake air amount Qin1 is the supercharging pressure detected by the supercharging pressure sensor 41, the engine speed of the diesel engine 1 detected by the rotational speed sensor 47, and the outside air temperature (intake air temperature detected by the outside air temperature sensor 38). ) Etc. can also be used for estimation including the exhaust gas recirculation amount.

  On the other hand, the intake air amount (estimated intake air amount Qin2) of the diesel engine 1 when intake air leaks from the intake passage 3 is the actual intake air amount Qair detected by the air flow meter 35 and the exhaust gas recirculation amount Qegr returned to the intake system. From the sum, it can be expressed as a value obtained by subtracting the leaked amount Qleak of the intake air leaking from the intake passage 3.

  Here, in a state where exhaust gas recirculation is being performed, even if there is a leakage of intake air from the intake passage 3, the difference between the estimated intake air amount Qin1 and the estimated intake air amount Qin2 is small. Also. When the feedback control of the supercharging pressure is performed, the supercharging pressure is recovered even when the intake air leaks from the intake passage 3, and the actual intake air amount detected by the air flow meter 35 is recovered. Since Qair increases, a difference between the estimated intake air amount Qin1 and the estimated intake air amount Qin2 hardly occurs, and the estimated intake air amount Qin1 and the estimated intake air amount Qin2 are compared to determine intake air leakage from the intake passage 3. Is difficult.

  Therefore, in the present embodiment, when the diesel engine 1 is in a predetermined operating condition, the result of performing a predetermined primary determination when determining whether or not the intake air leaks from the intake passage 3 is When the execution of the diagnosis of the presence or absence of intake air leakage is permitted, the secondary determination that is the diagnosis of the presence or absence of intake air leakage from the intake passage 3 is performed. The primary determination and the secondary determination are processed in the control unit 5. Here, as a predetermined operating condition, in an operating state with a small intake amount, even if the intake air leaks from the intake passage 3, the leakage amount decreases, making it difficult to diagnose the presence or absence of intake air leakage. Therefore, the operating condition where the intake air amount increases to some extent is good. In terms of engine speed and load, the medium / high rotation / medium / high load region is suitable as the predetermined operating condition.

  When the intake air is leaking from the intake passage 3, the turbocharger 21 is controlled so that the supercharging pressure becomes the target supercharging pressure because the supercharging pressure decreases with respect to the target supercharging pressure. Therefore, the actual exhaust pressure detected by the exhaust pressure sensor 31 increases as compared with the case where intake air does not leak from the intake passage 3. That is, when the intake air is leaking from the intake passage 3, the actual exhaust pressure detected by the exhaust pressure sensor 31 is larger than the estimated exhaust pressure estimated from the operating state of the diesel engine 1. The estimated exhaust pressure is calculated, for example, by searching a predetermined map from the fuel injection amount and the engine speed.

  Therefore, as the above-described primary determination, when the difference between the actual exhaust pressure detected by the exhaust pressure sensor 31 and the estimated exhaust pressure becomes equal to or greater than a predetermined value set in advance, intake air leaks from the intake passage 3. It is determined that there is a high possibility that the intake air leaks from the intake passage 3 and the execution of the diagnosis of the presence or absence of leakage of the intake air is permitted.

  FIG. 2 shows the correlation between the exhaust pressure and the torque in comparison with the case where no intake air leaks from the intake passage 3 and the case where a predetermined amount Q of intake air leaks from the intake passage 3. FIG.

  The characteristic lines A1 and B1 are characteristic lines when the intake air is not leaking from the intake passage 3, and the characteristic line A1 shows a characteristic example when the variation in the output characteristic of the exhaust pressure sensor 31 is not taken into consideration. The characteristic line B1 These show characteristic examples when the variation of the output characteristics of the exhaust pressure sensor 31 is added to the characteristic line A1. The characteristic lines C1 and D1 are characteristic lines when a predetermined amount Q of intake air is leaking from the intake passage 3, and the characteristic line C1 shows a characteristic example when the variation of the output characteristic of the exhaust pressure sensor 31 is not taken into consideration. The characteristic line D1 shows a characteristic example when the variation of the output characteristic of the exhaust pressure sensor 31 is added to the characteristic line C1.

  As shown in FIG. 2, the actual exhaust pressure when the intake air leaks from the intake passage 3 is not leaked from the intake passage 3 even if the variation in the output characteristics of the exhaust pressure sensor 31 is taken into consideration. This is clearly different from the actual exhaust pressure. That is, even if the variation in the output characteristics of the exhaust pressure sensor 31 is taken into account, the possibility of leakage of intake air from the intake passage 3 using the actual exhaust pressure that is the pressure in the exhaust passage 2 upstream of the turbine 22. Can be determined. Therefore, the estimated exhaust pressure estimated from the actual exhaust pressure detected by the exhaust pressure sensor 31 and the operating state of the diesel engine 1 is larger than the predetermined value A set in consideration of variations in the output characteristics of the exhaust pressure sensor 31. When the absolute value of the difference is large, it is determined that the possibility of intake air leakage is large, and the execution of the diagnosis of the presence or absence of intake air leakage from the intake passage 3 is permitted.

  Then, as the above-described secondary determination, when execution of diagnosis of the presence or absence of intake air leakage from the intake passage 3 is permitted, control is performed so that the exhaust gas recirculation amount becomes zero, and the estimated intake air amount Qin1 in this state By comparing the estimated intake air amount Qin2 with the intake air passage 3, the presence or absence of intake air leakage from the intake passage 3 is determined. Here, when there is no leakage of intake air from the intake passage 3, the estimated intake air amount Qin1 and the estimated intake air amount Qin2 should be equal to each other. Qin1 = Qleak. At the time of the secondary determination, the exhaust gas recirculation amount is zero, and the exhaust gas recirculation amounts included in the exhaust gas recirculation amounts Qegr and Qin1 are each zero. Therefore, as the secondary determination, specifically, the difference between the actual intake air amount Qair detected by the air flow meter 35 and the estimated intake air amount Qin1 estimated using the detected value of the supercharging pressure sensor 41 in this state. Is greater than or equal to a predetermined value set in advance, it is determined that intake air is leaking from the intake passage 3.

  FIG. 3 shows the correlation between the boost pressure and the intake air amount when the exhaust gas recirculation amount is set to a predetermined value or less, and the case where the intake air does not leak from the intake passage 3 and the intake air of the predetermined amount Q leaks from the intake passage 3. It is explanatory drawing shown by contrasting with the case where it is carrying out.

  The characteristic lines A2 and B2 are characteristic lines when the intake air does not leak from the intake passage 3, and the characteristic line A2 indicates variations in parts and output characteristics of various sensors (sensors used for estimating the intake air amount). An example of the characteristic when not considered is shown. The characteristic line B2 is an example of the characteristic when the component line and the output characteristic variation of various sensors (sensors used when estimating the intake air amount) are added to the characteristic line A2. Show. Characteristic lines C2 and D2 are characteristic lines when a predetermined amount Q of intake air is leaking from the intake passage 3, and the characteristic line C2 is output of component variations and various sensors (sensors used when estimating the intake air amount). An example of the characteristic when the characteristic variation is not taken into consideration is shown. The characteristic line D2 is added to the characteristic line C2 by a component variation and an output characteristic variation of various sensors (sensors used for estimating the intake air amount). Examples of characteristics are shown.

  As shown in FIG. 3, the intake air amount when the intake air leaks from the intake passage 3 is not leaked from the intake passage 3 even if the variation in the output characteristics of the various sensors is taken into account. The intake air amount is clearly different from the case. That is, it is possible to determine the presence or absence of leakage of intake air from the intake passage 3 using the intake air amount even in consideration of variations in parts and output characteristics of various sensors.

  Therefore, the actual intake air amount Qair detected by the air flow meter 35 and the supercharging pressure detected by the supercharging pressure sensor 41 are more than the predetermined value B set in consideration of variations in parts and output characteristics of various sensors. When the absolute value of the difference between the estimated intake air amount Qin1 estimated using the above is large, it is determined that the intake air is leaking from the intake passage 3.

  The calculation of the basic control amount and the feedback correction amount, the estimated exhaust pressure, and the estimated intake air amount in the feedback control of the target boost pressure and the boost pressure is performed in the control unit 5.

  In such an embodiment, when intake air leakage is suspected by the primary determination, the estimated intake air amount estimated from the operating state of the internal combustion engine and the upstream side of the compressor in a state where EGR is reduced than usual. Since the secondary determination using the detected intake air amount is performed, EGR is not reduced every time diagnosis is performed, and the leakage of intake air from the intake passage is accurately determined while suppressing deterioration of fuel consumption. It becomes possible to do.

  Also, the feedback control of the supercharging pressure seems to be performed so that the actual supercharging pressure becomes the target supercharging pressure by making the exhaust gas recirculation amount flowing into the intake passage 3 zero during the secondary determination. Even when the intake air is leaking from the intake passage 3, the estimated intake air amount Qin 1 estimated from the operating state of the diesel engine 1 and the actual intake air amount Qair detected upstream of the compressor 23. Therefore, it is possible to determine the leakage of intake air from the intake passage 3 even in consideration of variations in parts and output characteristics of various sensors (sensors used when estimating the intake air amount). Become.

  As a result of the primary determination, only when there is a high possibility that intake air is leaking from the intake passage 3, the secondary determination performed with the exhaust gas recirculation amount flowing into the intake passage 3 being zero is permitted. Further, it is possible to execute the diagnosis of the presence or absence of intake air leakage from the intake passage 3 while suppressing the rebound (influence) to the operation control of the diesel engine 1 by reducing the exhaust gas recirculation amount.

  FIG. 4 is a flowchart showing a control flow relating to the diagnosis of the presence or absence of intake air leakage from the intake passage 3 in the present embodiment described above.

  In S1, it is determined whether or not it is an operating condition in which it is possible to determine whether or not there is a leakage of intake air. If the operating condition can be determined, the process proceeds to S2, and if not, the current routine is terminated. To do.

  In S <b> 2, the actual exhaust pressure is detected by the exhaust pressure sensor 31. In S3, the estimated exhaust pressure is calculated from the operating state of the diesel engine 1.

  In S4, the absolute value of the difference between the actual exhaust pressure detected in S2 and the estimated exhaust pressure calculated in S3 is from a predetermined value A set in consideration of variations in the output characteristics of the exhaust pressure sensor 31. If it is larger, the process proceeds to S5, and if not, the current routine is terminated.

  In S5, control is performed so that the exhaust gas recirculation amount becomes zero. In S6, the actual intake air amount Qair is detected by the air flow meter 35.

  In S7, an estimated intake air amount Qin1 is calculated by searching a predetermined map from the boost pressure detected by the boost pressure sensor 41 and the engine speed.

  In S8, the absolute value of the difference between the actual intake air amount Qair detected in S6 and the estimated intake air amount Qin1 calculated in S7 is a predetermined value set in consideration of variations in parts and output characteristics of various sensors. It is determined whether or not it is greater than B. If it is greater, the process proceeds to S9, where it is determined that there is intake air leakage from the intake passage 3, and if not, the process proceeds to S10.

  In S10 and S11, the EGR control is switched to normal. That is, in S10 and S11, the EGR rate lowered in S5 is restored.

  Here, when it is determined in S9 that there is an intake air leak from the intake passage 3, for example, a warning light provided on the instrument panel of the driver's seat is turned on, and the driver leaks the intake air from the intake passage 3. Sense that there is. If it is determined in S9 that there is an intake air leak from the intake passage 3, the warning lamp is lit until the repair inspection for the intake air leak is completed at the factory or the like. Do not conduct a diagnosis of leakage.

  In FIG. 4, a series of control flow from S1 to S4 corresponds to primary determination, and a series of control flow from S5 to S9 corresponds to secondary determination.

  In the embodiment described above, the exhaust gas recirculation amount is controlled to be zero at the time of the secondary determination. However, if the accuracy of the diagnosis of the presence or absence of intake air leakage from the intake passage 3 can be ensured, In the secondary determination, the EGR rate may be set to be a predetermined value or less.

  In the embodiment described above, the primary determination is performed using the exhaust pressure, but the control amount of the variable nozzle 24 of the turbocharger 21, the feedback correction amount in the feedback control of the supercharging pressure, or the compressor 23 It is also possible to perform the primary determination using the intake air amount on the upstream side.

  As described above, when the intake air leaks from the intake passage 3, the turbocharger 21 is controlled so that the supercharging pressure becomes the target supercharging pressure because the supercharging pressure decreases with respect to the target supercharging pressure. Therefore, compared with the case where the intake air does not leak from the intake passage 3, the control amount of the variable nozzle 24 of the turbocharger 21 and the feedback correction amount in the feedback control of the supercharging pressure are respectively on the supercharging side. Will take the value. Further, when the supercharging pressure feedback control is performed, the intake air upstream of the compressor 23 is not leaked from the intake passage 3 when the intake air leaks from the intake passage 3. More than the case.

  Therefore, when the primary determination is performed using the control amount of the variable nozzle 24 of the turbocharger 21, it is estimated from the actual control amount of the variable nozzle 24 of the turbocharger 21 and the operating state of the diesel engine 1. The estimated control amount of the variable nozzle 24 when the intake air is not leaking from the intake passage 3 is compared, and when the difference between the two is equal to or greater than a predetermined value set in advance, It is determined that there is a high possibility that the intake air is leaking. The estimated control amount of the variable nozzle 24 when the intake air is not leaking from the intake passage 3 estimated from the operation state of the diesel engine 1 is calculated using, for example, a map from the engine speed and the fuel injection amount.

  When the primary determination is performed using the feedback correction amount in the supercharging pressure feedback control, the intake air from the intake passage 3 estimated from the actual feedback correction amount in the supercharging pressure feedback control and the operating state of the diesel engine 1 is taken in. Is compared with the estimated feedback correction amount in the feedback control of the supercharging pressure when there is no leakage, and when the difference between the two exceeds a predetermined value, the intake air from the intake passage 3 It is determined that there is a high possibility of leakage. The estimated feedback correction amount in the feedback control of the boost pressure when the intake air is not leaking from the intake passage 3 estimated from the operation state of the diesel engine 1 uses, for example, a map from the engine speed and the fuel injection amount. Is calculated.

  When primary determination is performed using the intake air amount on the upstream side of the compressor 23, the intake air amount detected by the air flow meter 35 in the state where the supercharging pressure feedback control is being performed and the operating state of the diesel engine 1 are determined. The estimated intake air amount on the upstream side of the compressor 23 when the intake air does not leak from the intake passage 3 in the state where the estimated supercharging pressure feedback control is being performed is compared, and the difference between the two is set in advance. When the predetermined value is exceeded, it is determined that there is a high possibility that the intake air from the intake passage 3 is leaking. The estimated intake air amount on the upstream side of the compressor 23 when the intake air is not leaking from the intake passage 3 estimated from the operation state of the diesel engine 1 is calculated using, for example, a map from the engine speed and the fuel injection amount. The

DESCRIPTION OF SYMBOLS 1 ... Diesel engine 2 ... Exhaust passage 3 ... Intake passage 4 ... EGR passage 5 ... Control unit 21 ... Turbocharger 22 ... Turbine 23 ... Compressor 31 ... Exhaust pressure sensor 35 ... Air flow meter 41 ... Supercharging pressure sensor

Claims (6)

A variable capacity turbocharger capable of variably controlling the nozzle opening degree of the turbine interposed in the exhaust passage of the internal combustion engine;
An intake air amount detection means for detecting an intake air amount upstream of a compressor of the turbocharger interposed in the intake passage of the internal combustion engine;
Exhaust recirculation means for recirculating part of the exhaust to the downstream side of the compressor in the intake passage;
Intake air amount estimating means for estimating the intake air amount from the operating state of the internal combustion engine,
In the intake air leakage diagnosis device for an internal combustion engine in which the supercharging pressure and the exhaust gas recirculation amount are controlled according to the operating state,
Based on the control state of the turbocharger, perform a primary determination of the presence or absence of intake air leakage from the intake passage,
When it is determined by the primary determination that there is a possibility of intake air leakage from the intake passage, the intake air amount detected by the intake air amount detection means in a state in which the exhaust gas recirculation amount set according to the operating state is reduced. Secondary determination of the presence or absence of leakage of intake air from the intake passage based on the amount of intake and the estimated intake air amount calculated by the intake air amount estimating means,
An intake air leakage diagnosis device for an internal combustion engine, wherein, as a result of secondary determination, it is determined that intake air is leaking from the intake passage based on an intake air amount and an estimated intake air amount.   2. The intake air leakage diagnosis device for an internal combustion engine according to claim 1, wherein the secondary determination is performed in a state where the exhaust gas recirculation amount is zero. Supercharging pressure detection means for detecting a supercharging pressure that is a pressure in the intake passage on the downstream side of the compressor is provided, and feedback control of the supercharging pressure is performed so that the actual supercharging pressure becomes the target supercharging pressure. An internal combustion engine,
Exhaust pressure detecting means for detecting an actual exhaust pressure which is a pressure in an exhaust passage upstream of the turbine;
Exhaust pressure estimating means for estimating the exhaust pressure that is the pressure in the exhaust passage on the upstream side of the turbine from the operating state of the internal combustion engine,
As the primary determination, the actual exhaust pressure detected by the exhaust pressure detecting means is compared with the estimated exhaust pressure calculated by the exhaust pressure estimating means, and the difference between the actual exhaust pressure and the estimated exhaust pressure is greater than or equal to a predetermined value. 3. The intake air leakage diagnosis device for an internal combustion engine according to claim 1, wherein execution of the secondary determination is permitted. Supercharging pressure detection means for detecting a supercharging pressure that is a pressure in the intake passage on the downstream side of the compressor is provided, and feedback control of the supercharging pressure is performed so that the actual supercharging pressure becomes the target supercharging pressure. An internal combustion engine,
A turbocharger control amount estimation means for estimating a control amount in variable control of the nozzle opening of the turbocharger from the operating state of the internal combustion engine;
As the primary determination, the actual control amount in the variable control of the nozzle opening of the turbocharger is compared with the estimated control amount calculated by the turbocharger control amount estimating means, and the actual control amount is estimated. The intake air leakage diagnosis apparatus for an internal combustion engine according to claim 1 or 2, wherein execution of the secondary determination is permitted when a difference in control amount is equal to or greater than a predetermined value. Supercharging pressure detection means for detecting a supercharging pressure that is a pressure in the intake passage on the downstream side of the compressor is provided, and feedback control of the supercharging pressure is performed so that the actual supercharging pressure becomes the target supercharging pressure. An internal combustion engine,
Feedback correction amount estimating means for estimating a feedback correction amount in feedback control of supercharging pressure from the operating state of the internal combustion engine,
As the primary determination, the actual feedback correction amount in the boost pressure feedback control is compared with the estimated feedback correction amount calculated by the feedback correction amount estimating means, and the difference between the actual feedback correction amount and the estimated feedback correction amount is determined. 3. The intake air leakage diagnosis apparatus for an internal combustion engine according to claim 1, wherein execution of the secondary determination is permitted when the value is equal to or greater than a predetermined value. 4. Supercharging pressure detection means for detecting a supercharging pressure that is a pressure in the intake passage on the downstream side of the compressor is provided, and feedback control of the supercharging pressure is performed so that the actual supercharging pressure becomes the target supercharging pressure. An internal combustion engine,
As the primary determination, the intake air amount detected by the intake air amount detecting means is compared with the estimated intake air amount calculated by the intake air amount estimating means in a state where feedback control of the supercharging pressure is being performed. The intake air leakage diagnosis device for an internal combustion engine according to claim 1 or 2, wherein execution of the secondary determination is permitted when a difference between the amount and the estimated intake air amount is a predetermined value or more.

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