Abnormality diagnosis device for internal combustion engine

Abstract

The invention relates to an abnormality diagnosis device for an internal combustion engine. The abnormality diagnosis device diagnoses the presence or absence of abnormality in the internal combustion engine. An internal combustion engine has a dry sump type lubrication system that circulates lubricating oil between the system and an oil tank external to the internal combustion engine. The internal combustion engine causes blow-by gas in the oil tank to flow back to an intake passage. The abnormality diagnosis device is provided with a pressure sensor that detects in-tank pressure, which is the pressure inside the oil tank. The abnormality diagnosis device is configured to perform a diagnosis process for diagnosing the presence or absence of an abnormality in the blow-by gas recirculation path on the basis of whether or not the tank pressure during low-load operation of the internal combustion engine exceeds a threshold value.

Description

Technical Field

[0001] This disclosure relates to an anomaly diagnostic device for an internal combustion engine with a dry oil sump lubrication system. Background Technology

[0002] As a diagnostic device for malfunctions in a dry sump type internal combustion engine that stores lubricating oil in an external oil tank, the device described in Japanese Patent Application Publication No. 2009-68452 is known. This diagnostic device places a resistor on the piping connecting the oil tank and the internal combustion engine, and detects detachment or breakage of the piping by monitoring the resistance value of this resistor. Summary of the Invention

[0003] Sometimes, holes are made in the piping. In this case, gas and / or lubricating oil may leak. Such piping openings cannot be detected in the aforementioned conventional diagnostic devices.

[0004] Methods for solving problems

[0005] One aspect of this disclosure provides an apparatus for diagnosing abnormalities in an internal combustion engine. The internal combustion engine has a dry sump lubrication system that circulates lubricating oil between itself and an external oil tank. The internal combustion engine allows blow-by gas from the oil tank to return to the intake passage. The abnormality diagnostic apparatus includes a pressure sensor that detects the internal pressure of the oil tank, i.e., the tank pressure. The abnormality diagnostic apparatus is configured to perform diagnostic processing to determine whether there is an abnormality in the blow-by gas return path based on whether the tank pressure exceeds a threshold when the internal combustion engine is operating under low load.

[0006] The aforementioned internal combustion engine fault diagnosis device has the following effect: it can include the opening of the piping that constitutes the return path, and diagnose whether there is any abnormality in the return path used to return the blow-by gas in the fuel tank to the intake passage. Attached Figure Description

[0007] Figure 1 This is a diagram schematically illustrating the structure of the fault diagnosis device for an internal combustion engine according to the first embodiment.

[0008] Figure 2 yes Figure 1 The flowchart shows the diagnostic process implemented by the abnormal diagnostic device.

[0009] Figure 3 This is a flowchart of the diagnostic process performed by the abnormality diagnostic device for the internal combustion engine according to the second embodiment. Detailed Implementation

[0010] (First Implementation)

[0011] The following is for reference Figure 1 and Figure 2The first embodiment of the fault diagnosis device for internal combustion engines is described in detail.

[0012] <Structure of an Internal Combustion Engine Malfunction Diagnosis Device>

[0013] Reference Figure 1 The structure of the internal combustion engine fault diagnosis device of this embodiment is explained.

[0014] First, the structure of the internal combustion engine 10 to which the fault diagnosis device of this embodiment is applied will be explained. The internal combustion engine 10 includes a cylinder 12 with a piston 11 flexibly arranged for reciprocating motion. Inside the cylinder 12, a combustion chamber 13 for combustion of the air-fuel mixture is formed by the piston 11. The piston 11 is connected to a crankshaft 15, which serves as the output shaft of the internal combustion engine 10, via a connecting rod 14. A crankcase 16 housing the crankshaft 15 is provided in the lower portion of the cylinder 12 in the internal combustion engine 10. The internal combustion engine 10 actually has multiple cylinders 12, but... Figure 1 Only one of them is shown. The combustion chamber 13 is connected to an intake passage 17, which serves as the intake air inlet, and an exhaust passage 18, which serves as the exhaust outlet. An air filter 19, a compressor 20, an intercooler 21, a throttle valve 22, and an intake manifold 23 are provided in the intake passage 17. A turbine 24, which rotates to receive the exhaust airflow, is provided in the exhaust passage 18. The air filter 19 is a filter device that filters dust and other contaminants from the intake air. The compressor 20 rotates in conjunction with the turbine 24, thereby compressing the intake air that has passed through the air filter 19. The intercooler 21 cools the intake air, which becomes hot due to compression by the compressor 20. The throttle valve 22 is a valve used to adjust the flow rate of the intake air in the intake passage 17, and is located downstream of the intercooler 21 in the intake passage 17. The intake manifold 23 is a branch pipe that distributes the intake air passing through the throttle valve 22 to the combustion chambers 13 of each cylinder 12.

[0015] <Structure of the lubrication system of internal combustion engine 10>

[0016] Next, the structure of the lubrication system of the internal combustion engine 10 will be described. The internal combustion engine 10 has a dry sump lubrication system. The dry sump lubrication system includes an oil tank 30 located outside the internal combustion engine 10. Moreover, this lubrication system is configured such that lubricating oil circulates between the oil tank 30 and the internal combustion engine 10 via a return oil pump 31 and a supply oil pump 32. The return oil pump 31 delivers lubricating oil from the crankcase 16 to the oil tank 30. The supply oil pump 32 supplies the lubricating oil stored in the oil tank 30 to the internal combustion engine 10. A pressure sensor 43 is provided in the oil tank 30 to detect the pressure inside. In the following description, the pressure inside the oil tank 30 will be referred to as the tank pressure.

[0017] <Ventilation System>

[0018] The lubricating oil delivered from the return oil pump 31 to the oil tank 30 contains blow-by gas, including combustion gases leaking from the combustion chamber 13 to the crankcase 16. The internal combustion engine 10 is equipped with a scavenging system that returns the blow-by gas flowing into the oil tank 30 to the intake air.

[0019] The ventilation system has two paths, a first return path 34 and a second return path 36, for returning cross-flow air from the oil tank 30 to the intake passage 17. The first return path 34 and the second return path 36 are constructed from hoses, pipes, and other piping, and PCV valves (described later). The end of the first return path 34 corresponding to the intake passage 17 is connected to the intake manifold 23. Conversely, the end of the second return path 36 corresponding to the intake passage 17 is connected to the portion of the intake passage 17 downstream of the air filter 19 and upstream of the compressor 20. A first PCV valve 35 and a second PCV valve 37 are respectively provided in the first return path 34 and the second return path 36 as one-way valves to prevent backflow of intake air from the intake passage 17 to the oil tank 30. The first PCV valve 35 is located at the connection point of the first return path 34 leading to the intake manifold 23. Conversely, the second PCV valve 37 is located at the connection point of the second return path 36 leading to the oil tank 30. It should be noted that the oil tank 30 is equipped with an oil separator 33 to separate oil mist from the blow-by gas. The oil tank 30 is configured to send blow-by gas to the first return path 34 and the second return path 36 via the oil separator 33.

[0020] Furthermore, the ventilation system includes an open valve 38 and an atmospheric inlet passage 39. The open valve 38, when opened, connects the portion of the intake passage 17 downstream of the air filter 19 and upstream of the compressor 20 to the fuel tank 30. The open valve 38 is designed to bring the pressure inside the fuel tank to near atmospheric pressure by opening the valve when the internal combustion engine 10 stops. The atmospheric inlet passage 39 is a passage that connects the portion of the intake passage 17 downstream of the air filter 19 and upstream of the compressor 20 to the crankcase 16.

[0021] exist Figure 1In the internal combustion engine 10, blow-by gas in the crankcase 16 is pumped to the oil reservoir 30 along with lubricating oil via the return oil pump 31. Based on the blow-by gas being pumped out, fresh air is supplied to the crankcase 16 via the atmospheric intake path 39. When the internal combustion engine 10 is operating at low load, the pressure inside the intake manifold 23 (hereinafter referred to as the intake manifold pressure) becomes negative. At this time, the blow-by gas in the oil reservoir 30 is drawn into the intake manifold 23 through the first return path 34 due to this negative pressure. When the load of the internal combustion engine 10 increases and it shifts to turbocharged operation, the intake manifold pressure becomes positive, and the suction of blow-by gas through the first return path 34 stops. If blow-by gas continues to be pumped from the crankcase 16 to the oil reservoir 30 using the return oil pump 31 in this state, the pressure inside the reservoir rises. During turbocharged operation, the pressure in the portion of the intake passage 17 upstream of the compressor 20 is also maintained near atmospheric pressure. Therefore, when the pressure inside the tank exceeds atmospheric pressure and becomes positive pressure, the gas leaking out of the oil tank 30 is sent to the air inlet passage 17 through the second return path 36. Thus, in Figure 1 In the internal combustion engine 10, blow-by gas from the crankcase 16 is returned to the intake via the oil tank 30, thereby scavenging the crankcase 16.

[0022] <Structure of the Abnormal Diagnostic Device>

[0023] The internal combustion engine 10 is controlled by an engine control module (ECM) 40. The ECM 40 includes a storage device 41 storing engine control programs and data, and a processor 42 for executing the programs. The ECM 40 controls the internal combustion engine 10 by executing the programs stored in the storage device 41 through the processor 42. The detection results from various sensors used to detect the operating status of the internal combustion engine 10 are input to the ECM 40. The sensors that input detection results to the ECM 40 include the aforementioned pressure sensor 43.

[0024] <Diagnosis and Treatment>

[0025] As part of the control of the internal combustion engine 10, the ECM40 performs diagnostic processing to diagnose whether there are any abnormalities in the first return path 34. Abnormalities in the first return path 34, which are the objects of this diagnostic processing, include openings or detachments in the piping constituting the first return path 34, such as the valve sticking of the first PCV valve 35.

[0026] Figure 2 This is a flowchart illustrating the diagnostic process. ECM40 executes repeatedly according to a predetermined control cycle during the operation of the internal combustion engine 10. Figure 2 The processing.

[0027] When it begins Figure 2During the processing, ECM40 first determines in step S100 whether the preconditions for diagnosis are met. In this embodiment, the fulfillment of all the conditions required for implementing the anomaly diagnosis is taken as a precondition for the anomaly diagnosis. Examples of conditions required for implementing the anomaly diagnosis are that the internal combustion engine 10 has been preheated, the atmospheric pressure is above a certain level, and the open valve 38 has closed. If the preconditions are met (yes), ECM40 proceeds to step S105; if they are not met (no), the anomaly diagnosis processing in this control cycle ends.

[0028] In step S105, the ECM40 determines whether the internal combustion engine 10 is operating under low load. For example, the ECM40 determines that the internal combustion engine 10 is operating under low load based on the engine speed and load rate being below a predetermined value. If the internal combustion engine 10 is operating under low load (yes), the ECM40 proceeds to step S110; otherwise, it terminates the abnormality diagnosis process in the current control cycle (no). Here, low load operation refers to the operating state of the internal combustion engine 10 where the intake manifold pressure is lower than a certain level.

[0029] In step S110, ECM40 acquires the tank pressure detected by pressure sensor 43. Then, in step S115, ECM40 determines whether the tank pressure is below a predetermined threshold. The threshold is set to a pressure above the highest intake manifold pressure during low-load operation but below atmospheric pressure. If the tank pressure is below the threshold (yes), ECM40 increments the value of the normal counter C1 in step S120 and resets the value of the abnormal counter C2, then proceeds to step S130. If the tank pressure exceeds the threshold (no), ECM40 resets the value of the normal counter C1 to zero in step S125 and increments the value of the abnormal counter C2, then proceeds to step S130. The value of the normal counter C1, in this operation, represents the duration of the state where the tank pressure is below the threshold, and the value of the abnormal counter C2 represents the duration of the state where the tank pressure exceeds the threshold.

[0030] In step S130, ECM40 determines whether the value of the normal counter C1 is above or above the predetermined normal determination value. Then, if the value of the normal counter C1 is above the normal determination value (Yes), ECM40 performs a normal determination (no abnormality in the first return path 34) in step S135, and then ends the processing in this control cycle. Conversely, if the value of the normal counter C1 is below the normal determination value (S130: No), ECM40 determines whether the abnormal counter C2 is above or above the predetermined abnormal determination value in step S140. Then, if the value of the abnormal counter C2 is above the abnormal determination value (Yes), ECM40 performs an abnormal determination (abnormality determination) (no) in step S145, and then ends the processing in this control cycle. It should be noted that when ECM40 determines an abnormality, it notifies the driver of the occurrence of the abnormality, for example, by illuminating a warning light.

[0031] <The Role of the First Implementation Method>

[0032] When the internal combustion engine 10 is operating at low load, the negative pressure in the intake manifold 23 is used to draw in the blow-by gas in the fuel tank 30 through the first return path 34, thereby performing gas exchange. Therefore, the pressure inside the fuel tank during low load operation becomes the same negative pressure as that in the intake manifold 23.

[0033] When abnormalities occur in the first return path 34, such as pipe detachment and / or opening, or valve sticking of the first PCV valve 35, blow-by gas cannot be introduced into the fuel tank 30 using the negative pressure of the intake manifold 23. Therefore, when an abnormality occurs, the pressure inside the tank will not become negative when the internal combustion engine 10 is operating at low load.

[0034] In response, the ECM40 checks whether the tank pressure exceeds a threshold during low-load operation. Furthermore, the ECM40 determines an anomaly if the tank pressure exceeds the threshold, thereby diagnosing any abnormalities in the first return path 34. Therefore, when an anomaly occurs in the first return path 34 as described above, the ECM40 diagnoses it as such.

[0035] <Effects of the First Implementation Method>

[0036] The anomaly diagnosis device of this embodiment can achieve the following effects.

[0037] (1) The ECM40 performs diagnostic processing to determine whether the pressure inside the tank exceeds a threshold when the internal combustion engine 10 is operating at low load. Therefore, the ECM40 can diagnose whether the first return path 34, which is used to return the blow-by gas in the oil tank 30 to the intake passage 17, is abnormal, including the opening of the piping.

[0038] (2) The internal combustion engine 10 using the fault diagnosis device of this embodiment includes a first PCV valve 35, which is a one-way valve for preventing intake air from flowing back from the intake passage 17 to the fuel tank 30 in the first return path 34. The first PCV valve 35 is provided at the connection portion in the first return path 34 that connects to the intake passage 17. Here, we consider the case where the first PCV valve 35 is provided at the connection portion in the first return path 34 that connects to the fuel tank 30. In this case, when the piping constituting the first return path 34 comes loose or is opened in the piping, external gas flows into the intake manifold 23 from there. Such external gas inflow can be detected by sensors already present in the internal combustion engine, such as an air flow meter or an air-fuel ratio sensor. In contrast, when the first PCV valve 35 is provided at the connection portion in the first return path 34 that connects to the intake passage 17, even if the piping comes loose and / or is opened, external gas will not flow into the intake manifold 23. Therefore, the abnormalities cannot be diagnosed using the sensors already provided. In the abnormality diagnosis device of this embodiment, even if the internal combustion engine 10 has a structure that cannot be diagnosed using the existing sensors, it is possible to diagnose whether there is an abnormality in the first return path 34.

[0039] (3) When the internal pressure of the tank exceeds the threshold for a predetermined period of time, the ECM40 will determine whether it is abnormal or normal. Therefore, it can suppress the influence of temporary changes in the detected internal pressure caused by noise and interference on the diagnostic results and improve the diagnostic accuracy.

[0040] (Second Implementation)

[0041] To perform high-precision anomaly diagnosis based on tank pressure during low-load operation using the anomaly diagnosis device of the first embodiment, it is preferable to perform the diagnosis when the difference between atmospheric pressure and intake manifold pressure is greater than a certain level. In the case of internal combustion engines with intermittent operation control, such as hybrid vehicles and vehicles with idle stop control, the engine often stops during low-load operation. Therefore, in internal combustion engines with intermittent operation control, the opportunity to perform anomaly diagnosis under preferred operating conditions that ensure diagnostic accuracy is limited. The anomaly diagnosis device of this embodiment is configured to control the opportunity for anomaly diagnosis in internal combustion engines with intermittent operation control. The hardware structure of the anomaly diagnosis device of this embodiment is similar to... Figure 1 Same. In the following description, in this embodiment, the same reference numerals are used for structures common to the first embodiment, and detailed descriptions thereof are omitted.

[0042] In this embodiment, the ECM40 performs anomaly diagnosis on the first return path 34 through preliminary diagnosis and formal diagnosis. Both preliminary and formal diagnosis are based on whether there is an anomaly in the first return path 34 according to the tank pressure. However, the execution conditions for the preliminary diagnosis are set such that, although easier to achieve than the execution conditions for the formal diagnosis, the diagnostic accuracy is lower. Furthermore, in this embodiment, the preliminary diagnosis is performed to determine whether there is a suspicion that an anomaly has occurred in the first return path 34, while the formal diagnosis is performed to confirm whether there is an anomaly in the first return path 34.

[0043] Figure 3 This is a flowchart illustrating the diagnostic control routine executed by the ECM40 in the anomaly diagnostic device of this embodiment. The ECM40 repeatedly executes this routine according to a predetermined control cycle during the operation of the internal combustion engine 10. Figure 3 The processing.

[0044] When ECM40 begins this routine, it first determines in step S200 whether the execution conditions for the preliminary diagnosis are met. The execution conditions for the preliminary diagnosis include conditions that allow for diagnosis based on tank pressure, but the execution conditions for the formal diagnosis are not met. Specifically, the execution conditions for the preliminary diagnosis are set as the condition of low-load operation with negative intake manifold pressure and not in idle. Furthermore, if the execution conditions for the preliminary diagnosis are met (yes), ECM40 proceeds to step S205; otherwise (no), it proceeds to step S220.

[0045] In step S205, ECM40 performs a preliminary diagnostic. The preliminary diagnostic is successful. Figure 2 The processing after step S110 is performed. Next, in step S210, ECM40 determines whether an abnormality was detected during the preliminary diagnosis. If an abnormality is detected (yes), ECM40 stops the intermittent operation control of the internal combustion engine 10 in step S215 and then proceeds to step S220. Conversely, if no abnormality is detected (no), ECM40 skips step S215 and proceeds to step S220.

[0046] In step S220, ECM40 determines whether the execution conditions for formal diagnosis are met. In this embodiment, the condition for formal diagnosis is that the vehicle is idling. If the execution conditions for formal diagnosis are met (yes), ECM40 proceeds to step S225; otherwise, it terminates the processing of this routine in the current control cycle.

[0047] In step S225, ECM40 performs a formal diagnosis. The formal diagnosis is conducted in the same manner as the preliminary diagnosis. Figure 2The process is implemented after step S110. However, in the case of formal diagnosis, as used for... Figure 2 In step S115, the threshold for determination is set to a lower pressure than that used in the preliminary diagnosis to perform the diagnosis. Next, in step S230, the ECM40 determines whether an abnormality is detected during the formal diagnosis. Then, if an abnormality is detected (Yes), in step S235, based on the diagnostic result that the first return path 34 is abnormal, the ECM40 ends the processing of this routine in the current control cycle. Conversely, if no abnormality is detected during the formal diagnosis (S230: No), step S235 is skipped and the processing of this routine in the current control cycle ends.

[0048] <Function of the Second Implementation Method>

[0049] In the internal combustion engine 10 that performs intermittent operation control, the engine often stops operating under low load, thus limiting the opportunity to perform high-precision anomaly diagnosis based on the first return path 34 of the tank pressure. In contrast, in this embodiment, even if diagnostic accuracy cannot be guaranteed, the ECM 40 performs a preliminary diagnosis if the conditions for tank pressure-based diagnosis are met. If an anomaly is detected in this preliminary diagnosis, although it cannot be definitively determined that an anomaly has occurred, it is considered highly probable. If an anomaly is detected in the preliminary diagnosis, the ECM 40 stops the intermittent operation control of the internal combustion engine 10. When intermittent operation control stops, the operation of the internal combustion engine 10 continues in the low-load operating region where normal operation stops. Furthermore, the ECM 40 performs a formal diagnosis when the intake manifold pressure drops to a level where high-precision diagnosis is possible, specifically when the engine is idling. It should be noted that the ECM 40 performs a formal diagnosis when the execution conditions are met during the implementation of intermittent operation control.

[0050] <Effects of the Second Implementation>

[0051] In addition to the effects of (1) to (3) mentioned above, the abnormality diagnosis device of this embodiment can also achieve the following effects.

[0052] (4) If an abnormality is detected during the preliminary diagnosis of the intermittent operation control of the internal combustion engine 10, the intermittent operation control is stopped. The formal diagnosis is then performed after the intermittent operation control is stopped, thereby diagnosing whether there is an abnormality in the first return path 34. Therefore, in the internal combustion engine 10 with intermittent operation control, the opportunity to diagnose the abnormality of the first return path 34 can also be ensured.

[0053] (5) The ECM40 operates the internal combustion engine 10 at a low intake manifold pressure by stopping the intermittent operation control. Moreover, the ECM40 performs formal diagnostics when the internal combustion engine 10 is operating at a low intake manifold pressure. Therefore, even in the internal combustion engine 10, which operates at a low frequency under low intake manifold pressure due to the intermittent operation control, abnormalities in the first return path 34 can be diagnosed with high precision.

[0054] (Other implementation methods)

[0055] The above embodiments can be implemented by modification as follows. The above embodiments and the following modifications can be combined with each other to implement them within the scope of technical inconsistency.

[0056] About Figure 3 Diagnostic control routines >

[0057] In the second embodiment, in both the preliminary diagnosis and the formal diagnosis, it is also possible to... Figure 2 The normal judgment value used in step S130 Figure 2 The different values ​​used in the abnormal judgment value in step S140 are determined.

[0058] • In the second embodiment, conditions other than those during idling stop can be set as execution conditions for formal diagnosis, as long as the conditions for diagnosis can be implemented with higher accuracy than those for the execution conditions of preliminary diagnosis.

[0059] About Figure 2 Diagnosis and treatment >

[0060] ·exist Figure 2 In the diagnostic process, a state where the tank pressure is below a threshold or exceeds the threshold for a predetermined period of time is considered normal / abnormal. Alternatively, the predetermined period of time can be omitted as a condition, and normal / abnormal can be determined solely by whether the tank pressure is below or exceeds the threshold.

[0061] • In the diagnostic process, it is also possible to skip the normal determination and only perform the abnormal determination. In this case, the diagnostic process is modified, for example, by omitting steps S120, S130, and S135, and proceeding to step S140 after the processing in step S125. Figure 2 The processing steps.

[0062] • Actions other than notifying the driver can also be taken when an abnormality is detected. For example, in order to reduce blow-by, the output of the internal combustion engine 10 can be limited when an abnormality is detected. Alternatively, the operation of the internal combustion engine 10 can be restricted before a normal operation determination is made, and the restriction can be lifted upon a normal operation determination.

[0063] <About the structure of the ventilation system>

[0064] • As long as it is the part of the intake passage 17 that is downstream of the throttle valve 22, the end of the first return path 34 corresponding to the intake passage 17 can also be connected to the part outside the intake manifold 23.

[0065] • The first PCV valve 35 may also be installed at a location other than the connection part that connects to the intake passage 17 in the first return path 34.

[0066] • In applications such as non-turbocharged internal combustion engines, it is also possible to... Figure 1 The ventilation system omits the second return path 36 and / or the second PCV valve 37. Alternatively, the open valve 38 may also be omitted.

[0067] <Other>

[0068] The anomaly diagnosis device described in the above embodiments and modifications can also be applied to... Figure 1 10 different internal combustion engines.

Claims

1. An abnormality diagnosing apparatus of an internal combustion engine that is configured to diagnose whether the internal combustion engine has an abnormality, wherein the internal combustion engine has a dry sump type lubrication system that circulates lubricating oil between an oil tank outside the internal combustion engine, and the internal combustion engine is configured to cause blow-by gas in the oil tank to flow back to an intake passage, the abnormality diagnosing apparatus includes a pressure sensor that detects a pressure inside the oil tank, that is, a tank internal pressure, and is configured to perform a diagnosis process that diagnoses whether the blow-by gas flow-back path has an abnormality based on whether the tank internal pressure exceeds a threshold value when the internal combustion engine is operating at a low load.

2. The abnormality diagnosing apparatus of the internal combustion engine according to claim 1, wherein the internal combustion engine includes a check valve that is provided at a connection portion in the flow-back path that is connected to the intake passage, and is configured to prevent intake air from flowing back from the intake passage to the oil tank.

3. The abnormality diagnosing apparatus of the internal combustion engine according to claim 1, wherein the abnormality diagnosing apparatus is configured to perform the diagnosis process while stopping an intermittent operation control of the internal combustion engine.

4. The abnormality diagnosing apparatus of the internal combustion engine according to claim 1, wherein the abnormality diagnosing apparatus is configured to perform the diagnosis process while the intermittent operation control of the internal combustion engine is being performed, and in the case where it is diagnosed in the diagnosis process that the flow-back path has an abnormality, the diagnosis process is performed again while the intermittent operation control is stopped.

5. The abnormality diagnosing apparatus of the internal combustion engine according to claim 1, wherein the diagnosis process includes diagnosing that the flow-back path has an abnormality in the case where a state in which the tank internal pressure exceeds the threshold value continues for a predetermined time or more. ​ ​ ​ ​ ​ ​ ​ ​

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