Abnormality diagnostic device

Abstract

To improve accuracy of a diagnosis.SOLUTION: An internal combustion engine 10 is configured so that when an intake air amount becomes an intake air amount reference value or larger by actuating a supercharger 11, a PCV pressure sensor value that is a detection value obtained by a PCV pressure sensor 35 becomes lower than atmospheric pressure. A processing circuit 51 of an abnormality diagnostic device 50 executes: deriving a corrected intake air amount by applying correction processing to the intake air amount; updating a determination parameter so that an updating amount becomes larger as a difference between the PCV pressure sensor value and the atmospheric pressure becomes larger when the supercharger 11 is in operation and the corrected intake air amount increases in a situation where the corrected intake air amount is the intake air amount reference value or larger; and making a diagnosis to determine whether an abnormality occurs in a portion on an intake passage 24 side of a connecting portion of the PCV pressure sensor 35 in a blow-by gas passage 31 on the basis of a comparison between the determination parameter and a parameter threshold value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an abnormality diagnosis device that is applied to an internal combustion engine having a function of returning blow-by gas that has leaked from a combustion chamber into a crankcase to an intake passage. [Background technology]

[0002] The internal combustion engine disclosed in Patent Document 1 includes an accumulation section where blow-by gas accumulates, a blow-by gas passage that connects the accumulation section to the intake passage, and a pressure sensor that detects the pressure of the blow-by gas passage. The detected value of the pressure sensor is called a PCV pressure sensor value. The blow-by gas passage is connected to a portion of the intake passage upstream of the turbocharger compressor. In such an internal combustion engine, when the blow-by gas passage is normally connected to the intake passage, there is a correlation between changes in the intake air amount and changes in the PCV pressure sensor value. For example, when the intake air amount increases, the PCV pressure sensor value decreases.

[0003] Therefore, when the intake air amount is changing, the control device of the internal combustion engine derives a determination parameter based on the difference between the PCV pressure sensor value and atmospheric pressure.The control device diagnoses whether or not an abnormality in which blow-by gas leaks to the outside has occurred in a portion of the blow-by gas passage closer to the intake passage than the connection portion of the pressure sensor, based on a comparison between the determination parameter and a threshold value. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-186702 Summary of the Invention [Problem to be solved by the invention]

[0005] Depending on the position and shape of the pressure sensor and other detection systems, there may be a delay in the response of the PCV pressure sensor value to changes in the intake air volume. Depending on the degree of this delay, the accuracy of the above diagnosis may be reduced. [Means for solving the problem]

[0006] The abnormality diagnosis device for solving the above problem is applied to an internal combustion engine that includes a supercharger, an accumulation section that accumulates blow-by gas that has leaked from a combustion chamber into a crankcase, a blow-by gas passage that connects a portion of an intake passage upstream of a compressor of the supercharger with the accumulation section, and a PCV pressure sensor that is connected to the blow-by gas passage and detects the pressure of the blow-by gas passage, and is configured so that when the intake air amount becomes equal to or greater than an intake air amount reference value due to operation of the supercharger, the PCV pressure sensor value that is the detected value of the PCV pressure sensor becomes lower than atmospheric pressure. The abnormality diagnosis device includes a processing circuit. The processing circuit performs a correction process on the intake air amount according to a response delay of a change in the PCV pressure sensor value relative to a change in the intake air amount, thereby deriving a corrected intake air amount whose start of change is delayed relative to the start of the change in the intake air amount by the time of the response delay; when the supercharger is operating and the corrected intake air amount is equal to or greater than the intake air amount reference value and the corrected intake air amount is increasing, updates the determination parameter so that the update amount of the determination parameter increases as the magnitude of the difference between the PCV pressure sensor value and atmospheric pressure increases; and diagnoses whether or not an abnormality has occurred in a portion of the blow-by gas passage closer to the intake passage than the connection point of the PCV pressure sensor, based on a comparison between the determination parameter and a threshold value of the determination parameter. [Effects of the Invention]

[0007] The abnormality diagnosis device has the effect of improving the accuracy of diagnosis. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an internal combustion engine equipped with an abnormality diagnosis device according to an embodiment. [Figure 2] FIG. 2 is a diagram showing the transition of the intake air amount and the transition of the PCV pressure sensor value when supercharging is performed by operating the supercharger. [Figure 3] FIG. 3 is a diagram showing the transition of the corrected intake air amount and the transition of the PCV pressure sensor value when supercharging is performed by operating the supercharger. [Figure 4] FIG. 4 is a flowchart showing a series of processes executed by a processing circuit included in the abnormality diagnosis device of FIG. [Figure 5] FIG. 5 is a timing chart for diagnosing whether or not a leakage abnormality has occurred. [Figure 6] FIG. 6 is a diagram showing the transition of the corrected intake air amount and the transition of the PCV pressure sensor value when supercharging is performed by operating the supercharger in a modified example of the abnormality diagnostic device. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the abnormality diagnostic device will be described below with reference to FIGS. <Configuration of an internal combustion engine> 1 shows an internal combustion engine 10 equipped with an abnormality diagnosis device 50. The internal combustion engine 10 is equipped with an exhaust-driven supercharger 11. A crankcase 13 is attached to the bottom of a cylinder block 12 of the internal combustion engine 10. A crankshaft 14 is housed within the crankcase 13. An oil pan 15 is attached to the bottom of the crankcase 13 to store oil circulating within the internal combustion engine 10.

[0010] A cylinder head 16 is attached to the top of the cylinder block 12. A plurality of cylinders 17 are defined by the cylinder block 12 and the cylinder head 16. A head cover 18 is attached to the top of the cylinder head 16.

[0011] A piston 19 is housed in each of the cylinders 17. Each of the pistons 19 is connected to the crankshaft 14 via a connecting rod 20. The reciprocating motion of each of the pistons 19 within the cylinder 17 causes the crankshaft 14 to rotate.

[0012] The internal combustion engine 10 is provided with a communication passage 21 that connects the space defined by the cylinder head 16 and the head cover 18 with the inside of the crankcase 13. The communication passage 21 spans the cylinder block 12 and the cylinder head 16. Therefore, blow-by gas that leaks into the crankcase 13 from a combustion chamber 22 defined in each cylinder 17 flows into the space through the communication passage 21. In other words, the space defined by the cylinder head 16 and the head cover 18 functions as an "accumulation section 23" where blow-by gas accumulates.

[0013] An intake passage 24 and an exhaust passage 25 are connected to the cylinder head 16. Intake air that flows through the intake passage 24 is introduced into the combustion chamber 22. In the combustion chamber 22, an air-fuel mixture containing the intake air and fuel is burned. Exhaust gas generated in the combustion chamber 22 by the combustion of the air-fuel mixture is discharged into the exhaust passage 25.

[0014] The supercharger 11 includes a turbine 111 and a compressor 112. The turbine 111 is provided in the exhaust passage 25. The compressor 112 is provided in the intake passage 24 at a position upstream of the throttle valve 26.

[0015] The internal combustion engine 10 is equipped with a blow-by gas treatment device 30 that returns blow-by gas accumulated in the accumulation section 23 to the intake passage 24. Hereinafter, the blow-by gas treatment device 30 will be referred to as the "PCV treatment device 30." A portion of the intake passage 24 upstream of the compressor 112 will be referred to as the "upstream intake passage 241." The PCV treatment device 30 is equipped with a blow-by gas passage 31 that connects the accumulation section 23 and the upstream intake passage 241, and a PCV pressure sensor 35 that detects the absolute pressure in the blow-by gas passage 31. The PCV pressure sensor 35 outputs a detection signal corresponding to the absolute pressure in the blow-by gas passage 31 to the abnormality diagnosis device 50.

[0016] The blow-by gas passage 31 has a joint 32 attached to the head cover 18 and a blow-by gas pipe 33. One end of the blow-by gas pipe 33 is connected to the joint 32, while the other end of the blow-by gas pipe 33 is connected to the upstream intake passage 241. A PCV pressure sensor 35 is connected to the joint 32.

[0017] <Sensor> The internal combustion engine 10 is equipped with a plurality of sensors that output detection signals according to the detection results to the abnormality diagnosis device 50. The plurality of sensors includes an atmospheric pressure sensor 41 and an air flow meter 42 in addition to the PCV pressure sensor 35. The atmospheric pressure sensor 41 detects the atmospheric pressure, which is the pressure around the internal combustion engine 10. The air flow meter 42 detects the flow rate of intake air flowing through the intake passage 24. Hereinafter, the absolute pressure based on the detection signal of the PCV pressure sensor 35 will be referred to as the "PCV pressure sensor value PCVS." The pressure based on the detection signal of the atmospheric pressure sensor 41 will be referred to as the "atmospheric pressure PHAC." The flow rate of intake air based on the detection signal of the air flow meter 42 will be referred to as the "intake air amount GA."

[0018] <Abnormality diagnosis device> The abnormality diagnosis device 50 diagnoses whether or not a leakage abnormality has occurred in the PCV treatment device 30. A leakage abnormality is an abnormality in which blow-by gas may leak to the outside from a portion of the blow-by gas passage 31 that is closer to the upstream intake passage 241 than the connection point of the PCV pressure sensor 35. A leakage abnormality may occur when any of the following occurs: the blow-by gas pipe 33 comes off the intake passage 24, the blow-by gas pipe 33 comes off the joint 32, or the blow-by gas pipe 33 is damaged.

[0019] The abnormality diagnosis device 50 includes a processing circuit 51. One example of the processing circuit 51 is an electronic control device. In this case, the processing circuit 51 includes a CPU 52, a first memory 53, and a second memory 54. The first memory 53 stores a control program executed by the CPU 52. The second memory 54 stores the results of calculations by the CPU 52, etc. The CPU 52 executes the control program in the first memory 53, causing the processing circuit 51 to diagnose whether a leakage abnormality has occurred.

[0020] Here, referring to FIG. 2, the relationship between the intake air amount GA and the PCV pressure sensor value PCVS when no leakage abnormality occurs will be described. FIG. 2(A) shows an example of how the intake air amount GA changes when supercharging is performed by operating the supercharger 11. When the intake air amount GA changes as shown in FIG. 2(A), the PCV pressure sensor value PCVS changes in conjunction with the change in the intake air amount GA, as shown in FIG. 2(B). For example, when the intake air amount GA decreases, as in the period from timing t11 to timing t12, the PCV pressure sensor value PCVS increases. In other words, the PCV pressure sensor value PCVS increases toward 0 (zero). On the other hand, when the intake air amount GA increases, as in the period from timing t12 to timing t13, the PCV pressure sensor value PCVS decreases.

[0021] However, the connection portion of the PCV pressure sensor 35 in the blow-by gas passage 31 is separated from the connection portion of the blow-by gas passage 31 with the intake passage 24. Therefore, a response delay occurs in the change in the PCV pressure sensor value PCVS relative to the change in the intake air amount GA. The degree of this response delay depends on the position of the PCV pressure sensor 35. Therefore, the delay time TMart, which indicates the degree of this response delay, can be estimated.

[0022] Therefore, when diagnosing whether a leakage abnormality has occurred, the processing circuit 51 performs a correction process on the intake air amount GA according to the degree of response delay of the change in the PCV pressure sensor value PCVS relative to the change in the intake air amount GA, thereby deriving a corrected intake air amount GAa. The corrected intake air amount GAa is derived so that the start of change in the corrected intake air amount GAa is delayed by the time of the response delay from the start of change in the intake air amount GA.

[0023] In this embodiment, the processing circuit 51 executes a correction process to delay the change in the intake air amount GA by a delay time TMR, thereby deriving the corrected intake air amount GAa. The delay time TMR corresponds to the response delay time. In other words, by executing the correction process, the processing circuit 51 derives the intake air amount GA at a time point the delay time TMR before the current time as the corrected intake air amount GAa.

[0024] Figure 3 shows the changes in the corrected intake air amount GAa and the PCV pressure sensor value PCVS when no leakage abnormality occurs. As shown in (A) and (B) of Figure 3, the degree of response delay in the change in the PCV pressure sensor value PCVS to a change in the corrected intake air amount GAa is smaller than the degree of response delay in the change in the PCV pressure sensor value PCVS to a change in the intake air amount GA.

[0025] The processing circuit 51 uses the corrected intake air amount GAa to derive a determination parameter Z, which will be described later. Then, the processing circuit 51 diagnoses whether or not a leakage abnormality has occurred based on a comparison between the determination parameter Z and a parameter threshold Zth, which is a threshold value for the determination parameter Z.

[0026] <Diagnosis processing> The diagnostic process, which is a series of processes for diagnosing whether or not a leakage abnormality has occurred, will be described with reference to Fig. 4. The processing circuit 51 repeatedly executes the diagnostic process while the engine is running.

[0027] In step S11, the processing circuit 51 performs the above-described correction process on the intake air amount GA to derive a corrected intake air amount GAa. In the following step S13, the processing circuit 51 determines whether the corrected intake air amount GAa is equal to or greater than the intake air amount reference value GAth. The intake air amount reference value GAth is set to satisfy the following conditions (A1) and (A2). Therefore, even if the engine is running, if supercharging by the supercharger 11 is not being performed, the intake air amount GA will not be equal to or greater than the intake air amount reference value GAth.

[0028] (A1) When supercharging is performed by the operation of the supercharger 11, the intake air amount GA becomes equal to or greater than the intake air amount reference value GAth. (A2) When the intake air amount GA is equal to or greater than the intake air amount reference value GAth, the PCV pressure sensor value PCVS becomes lower than the atmospheric pressure PHAC.

[0029] If the corrected intake air amount GAa is equal to or greater than the intake air amount reference value GAth (S13: YES), the processing circuit 51 proceeds to step S15. If the corrected intake air amount GAa is less than the intake air amount reference value GAth (S13: NO), the processing circuit 51 proceeds to step S31.

[0030] In step S15, the processing circuit 51 updates the measurement counter CNT so that it increases by 1. The measurement counter CNT corresponds to the elapsed time since the derivation process of the change correspondence value X, which will be described later, started. The point at which the measurement counter CNT is updated from 0 (zero) to 1 by the process of step S15 can be said to be the start point of a predetermined monitoring period in which a decrease in the PCV pressure sensor value PCVS is monitored.

[0031] In the next step S17, the processing circuit 51 derives a PCV pressure decrease amount ΔPCVS, which is the amount of decrease in the PCV pressure sensor value PCVS. The PCV pressure sensor value PCVS at the start of the monitoring period is set to a reference value PCVSb. If the current PCV pressure sensor value PCVS is equal to or less than the reference value PCVSb, the processing circuit 51 derives the absolute value of the difference between the current PCV pressure sensor value PCVS and the reference value PCVSb as the PCV pressure decrease amount ΔPCVS. On the other hand, if the current PCV pressure sensor value PCVS is higher than the reference value PCVSb, the processing circuit 51 derives 0 (zero) as the PCV pressure decrease amount ΔPCVS. In the following step S19, the processing circuit 51 derives the sum of the change response value X and the PCV pressure decrease amount ΔPCVS as the latest value of the change response value X. That is, the processing circuit 51 can derive the change response value X by integrating the PCV pressure decrease amount ΔPCVS.

[0032] In the next step S21, the processing circuit 51 determines whether the measurement counter CNT is equal to or greater than the judgment counter CNTth. The judgment counter CNTth is set as a criterion for determining whether the monitoring period has ended. If the measurement counter CNT is equal to or greater than the judgment counter CNTth (S21: YES), the processing circuit 51 moves the processing to step S23. If the measurement counter CNT is less than the judgment counter CNTth (S21: NO), the processing circuit 51 temporarily ends the diagnostic processing.

[0033] In step S23, the processing circuit 51 determines whether the increase ΔGAa in the corrected intake air amount GAa during the monitoring interval is equal to or greater than the judgment increase ΔGAath. The processing circuit 51 can derive the increase ΔGAa by subtracting the corrected intake air amount GAa at the start of the monitoring interval from the corrected intake air amount GAa at the end of the monitoring interval. A criterion for determining whether the change in the intake air amount GA is large is set as the judgment increase ΔGAath. For example, the processing circuit 51 may set the judgment increase ΔGAath so that the higher the engine speed NE, the larger the value.

[0034] If the increase amount ΔGAa is equal to or greater than the determined increase amount ΔGAath (S23: YES), the processing circuit 51 proceeds to step S25. If the increase amount ΔGAa is less than the determined increase amount ΔGAath (S23: NO), the processing circuit 51 proceeds to step S31.

[0035] In step S25, the processing circuit 51 updates the number of accumulations N so that the number of accumulations N increases by 1. In the following step S27, the processing circuit 51 derives the sum of the decision parameter Z and the change correspondence value X as the latest value of the decision parameter Z. That is, the processing circuit 51 can derive the decision parameter Z by accumulating the change correspondence value X.

[0036] In the next step S29, the processing circuit 51 determines whether the number of accumulations N is equal to or greater than a predetermined number Nth. For example, the predetermined number Nth is set to a positive number equal to or greater than 2. If the number of accumulations N is equal to or greater than the predetermined number Nth (S29: YES), the processing circuit 51 shifts the processing to step S33. If the number of accumulations N is less than the predetermined number Nth (S29: NO), the processing circuit 51 shifts the processing to step S31.

[0037] In step S31, the processing circuit 51 resets both the measurement counter CNT and the change correspondence value X to 0 (zero). After that, the processing circuit 51 temporarily ends the diagnostic processing. In step S33, the processing circuit 51 determines whether the judgment parameter Z is equal to or greater than the parameter threshold value Zth. The judgment criterion for diagnosing whether a leakage abnormality has occurred using the judgment parameter Z is set as the parameter threshold value Zth. If the judgment parameter Z is equal to or greater than the parameter threshold value Zth (S33: YES), the processing circuit 51 shifts the processing to step S35. If the judgment parameter Z is less than the parameter threshold value Zth (S33: NO), the processing circuit 51 shifts the processing to step S37.

[0038] In step S35, the processing circuit 51 determines that no leakage abnormality has occurred, that is, that no abnormality has occurred in the portion of the blow-by gas passage 31 closer to the intake passage 24 than the connection portion of the PCV pressure sensor 35. Then, the processing circuit 51 temporarily ends the diagnostic process.

[0039] In step S37, the processing circuit 51 diagnoses that a leakage abnormality has occurred, that is, that an abnormality has occurred in a portion of the blow-by gas passage 31 closer to the intake passage 24 than the connection portion of the PCV pressure sensor 35. Then, the processing circuit 51 temporarily ends the diagnostic process.

[0040] <Actions and Effects of This Embodiment> The operation and effect of this embodiment will be described with reference to (A) to (D) of Figure 5. In (C) of Figure 5, the change in the PCV pressure sensor value PCVS when no leakage abnormality has occurred is shown by a solid line, while the change in the PCV pressure sensor value PCVS when a leakage abnormality has occurred is shown by a two-dot chain line. In (D) of Figure 5, the change in the determination parameter Z when no leakage abnormality has occurred is shown by a solid line, while the change in the determination parameter Z when a leakage abnormality has occurred is shown by a two-dot chain line.

[0041] When the intake air begins to be pressurized by the operation of the supercharger 11, the intake air amount GA begins to increase. Then, with a slight delay from when the intake air amount GA starts to increase, the PCV pressure sensor value PCVS begins to increase. While the engine is running, the processing circuit 51 derives the corrected intake air amount GAa by performing a correction process on the intake air amount GA. The timing at which the corrected intake air amount GAa due to supercharging by the supercharger 11 starts to increase is delayed compared to the timing at which the intake air amount GA due to supercharging by the supercharger 11 starts to increase. Therefore, the difference between the timing at which the corrected intake air amount GAa starts to increase and the timing at which the PCV pressure sensor value PCVS starts to decrease is almost eliminated.

[0042] At time t21, the corrected intake air amount GAa becomes equal to or greater than the intake air amount reference value GAth, and the monitoring section PRD begins, in which the PCV pressure sensor value PCVS is monitored for a decrease. After time t21, the corrected intake air amount GAa increases, and the PCV pressure sensor value PCVS decreases.

[0043] Here, immediately after the intake air amount GA starts to increase, the PCV pressure sensor value PCVS has not yet started to decrease. Therefore, if the monitoring section PRD starts when the intake air amount GA becomes equal to or greater than the intake air amount reference value GAth, the change response value X does not increase very much in the early stage of the monitoring section PRD. As a result, the determination parameter Z, which is the integrated value of the change response value X, does not increase very much. As a result, because the determination parameter Z does not increase, there is a risk that the processing circuit 51 will erroneously diagnose that a leakage abnormality has occurred even though no leakage abnormality actually has occurred.

[0044] In this regard, in this embodiment, the monitoring section PRD starts from the timing when the corrected intake air amount GAa becomes equal to or greater than the intake air amount reference value GAth. Therefore, even in the early stage of the monitoring section PRD, the change response value X increases as the corrected intake air amount GAa increases. As a result, when the corrected intake air amount GAa is increasing, the processing circuit 51 can update the decision parameter Z so that the update amount of the decision parameter Z increases as the magnitude of the difference between the PCV pressure sensor value PCVS and the atmospheric pressure PHAC increases.

[0045] When no leakage abnormality has occurred and blow-by gas can be properly introduced into the intake passage 24 via the blow-by gas passage 31, the determination parameter Z increases by an amount corresponding to the increase in the corrected intake air amount GAa. Therefore, the processing circuit 51 can prevent itself from diagnosing that a leakage abnormality has occurred when in fact no leakage abnormality has occurred.

[0046] On the other hand, when a leakage abnormality occurs, even if the corrected intake air amount GAa increases, the decrease in the PCV pressure sensor value PCVS is small. Therefore, the determination parameter Z does not increase compared to when no leakage abnormality occurs. As a result, in the example shown in Figure 5, the processing circuit 51 can diagnose that a leakage abnormality has occurred at timing t22 when the cumulative number N reaches the predetermined number Nth.

[0047] Therefore, the abnormality diagnostic device 50 can improve the accuracy of diagnosing whether or not a leakage abnormality has occurred. <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0048] The correction process may be different from the correction process executed in the above embodiment as long as it can delay the start of change in the corrected intake air amount GAa from the start of change in the intake air amount GA. For example, the processing circuit 51 may execute a smoothing process to smooth the change in the intake air amount as the correction process. One example of the smoothing process is a known filtering process.

[0049] Figure 6 shows the changes in the PCV pressure sensor value PCVS and the changes in the corrected intake air amount GAb when no leakage abnormality occurs. The corrected intake air amount GAb is a corrected intake air amount that can be derived by applying a smoothing process to the intake air amount GA. As shown in Figures 6(A) and 6(B), the degree of response delay in the change in the PCV pressure sensor value PCVS to a change in the corrected intake air amount GAb is smaller than the degree of response delay in the change in the PCV pressure sensor value PCVS to a change in the intake air amount GA.

[0050] As long as a value corresponding to the amount of change in the PCV pressure sensor value PCVS during the monitoring interval can be derived as the change response value, the processing circuit 51 may derive a value different from the values ​​described in the above embodiment as the change response value. For example, the processing circuit 51 may derive a trajectory length, which is the length of a line showing the change in the PCV pressure sensor value PCVS during the monitoring interval, as the change response value.

[0051] The processing circuit 51 may derive the average value of a plurality of change correspondence values ​​X as the determination parameter. The PCV pressure sensor 35 may be a sensor that detects gauge pressure, which is a relative pressure based on atmospheric pressure.

[0052] The processing circuit 51 is not limited to a circuit having a CPU and ROM and executing software processing. In other words, the processing circuit 51 may have any one of the following configurations (a), (b), and (c):

[0053] (a) The processing circuit 51 includes one or more processors that execute various processes according to a computer program. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or special-purpose computer.

[0054] (b) The processing circuit 51 includes one or more dedicated hardware circuits that perform various processes. Examples of dedicated hardware circuits include application-specific integrated circuits (ASICs) or FPGAs. ASIC stands for "Application Specific Integrated Circuit," and FPGA stands for "Field Programmable Gate Array."

[0055] (c) The processing circuitry 51 includes one or more processors that execute some of the various processes in accordance with a computer program, and one or more dedicated hardware circuits that execute the remaining processes among the various processes. [Explanation of symbols]

[0056] 10...internal combustion engine, 11...supercharger, 112...compressor, 13...crankcase, 22...combustion chamber, 23...accumulator, 24...intake passage, 241...upstream intake passage, 31...blow-by gas passage, 35...PCV pressure sensor, 50...abnormality diagnosis device, 51...processing circuit

Claims

1. the pressure sensor is adapted to an internal combustion engine including a turbocharger, an accumulation section for accumulating blow-by gas leaked from a combustion chamber into a crankcase, a blow-by gas passage communicating a portion of an intake passage upstream of a compressor of the turbocharger with the accumulation section, and a PCV pressure sensor connected to the blow-by gas passage and detecting the pressure of the blow-by gas passage, and configured such that when the intake air amount becomes equal to or greater than an intake air amount reference value due to operation of the turbocharger, the PCV pressure sensor value, which is the detected value of the PCV pressure sensor, becomes lower than atmospheric pressure; processing circuitry; The processing circuitry by applying a correction process to the intake air amount according to a response delay of a change in the PCV pressure sensor value relative to a change in the intake air amount, deriving a corrected intake air amount whose start of change is delayed relative to the start of the change in the intake air amount by the time of the response delay; updating the determination parameter such that the update amount of the determination parameter increases as the magnitude of the difference between the PCV pressure sensor value and atmospheric pressure increases, when the supercharger is operating and the corrected intake air amount is equal to or greater than the intake air amount reference value; and diagnosing whether or not an abnormality has occurred in a portion of the blow-by gas passage closer to the intake passage than a connection portion of the PCV pressure sensor based on a comparison between the determination parameter and a threshold value of the determination parameter. Abnormality diagnosis device.

2. The time corresponding to the degree of the response delay is a delay time, The correction process is a process of delaying the change in the intake air amount by the delay time. The abnormality diagnosis device according to claim 1 .

3. The correction process is a process for smoothing the change in the intake air amount, The degree of smoothing of the intake air amount by the smoothing process is a degree corresponding to the degree of the response delay. The abnormality diagnosis device according to claim 1 .

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