Internal combustion engine abnormality diagnosis device

Abstract

To provide an abnormality diagnostic device for an internal combustion engine that improves accuracy of an abnormality diagnosis of a blow-by gas treatment device.SOLUTION: An abnormality diagnostic device 50 includes: a change corresponding value derivation section 53 that derives a change corresponding value corresponding to a change amount of a PCV pressure sensor value in a predetermined monitoring section when the PCV pressure sensor value that is a pressure detected by a PCV pressure sensor 35 is negative pressure lower than atmospheric pressure; a parameter derivation section 54 that derives a determination parameter obtained by integrating the plurality of change corresponding values; and a leakage abnormality determination section 55 that makes a diagnosis to determine that an abnormality has occurred in a blow-by gas passage when the determination parameter is smaller than a parameter threshold value. The parameter derivation section 54 derives the determination parameter by integrating the change corresponding values derived when a boost pressure sensor value detected by a boost pressure sensor 291 is outside a preset determination pressure range in the vicinity of the atmospheric pressure and a suction air amount changes.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an abnormality diagnosis device for an internal combustion engine, and more particularly to an abnormality diagnosis device for an internal combustion engine that diagnoses an abnormality in a blow-by gas device of an internal combustion engine. [Background technology]

[0002] There is known an internal combustion engine equipped with a blow-by gas treatment device that returns the blow-by gas leaked from the combustion chamber into the crankcase to the intake passage. In such an internal combustion engine, if a blow-by gas passage through which the blow-by gas to be returned to the intake passage flows becomes detached from the intake passage or is damaged, the blow-by gas passing through the blow-by gas passage may leak to the outside. Such an abnormality in the blow-by gas passage can be detected based on the pressure in the blow-by gas passage.

[0003] For example, Patent Document 1 discloses an abnormality diagnosis device for an on-board internal combustion engine that is applied to an on-board internal combustion engine that includes a supercharger, a blow-by gas passage, and a PCV pressure sensor. The abnormality diagnosis device described in Patent Document 1 includes a parameter derivation unit that derives a judgment parameter so that when the PCV pressure sensor value is lower than the atmospheric pressure under a situation in which the amount of change in the intake air amount is equal to or greater than a judgment change amount, the value is larger when the difference between the PCV pressure sensor value and the atmospheric pressure is large than when the difference is small, and a leakage abnormality diagnosis unit that executes a leakage abnormality diagnosis process to diagnose that an abnormality has occurred in a portion of the blow-by gas passage closer to the intake passage than the connection part of the PCV pressure sensor when the judgment parameter is less than a parameter threshold value. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-186702 A Summary of the Invention [Problem to be solved by the invention]

[0005] In such an internal combustion engine, when the non-supercharging region where supercharging by the supercharger is not performed and the supercharging region where supercharging by the supercharger is performed are switched, the flow of the blow-by gas through the blow-by gas passage is reversed. Therefore, with the switch between the non-supercharging region and the supercharging region, a stagnation period occurs in which the negative pressure in the blow-by gas passage is unlikely to increase even if the intake air amount increases. Therefore, if an abnormality diagnosis is performed during this stagnation period using the technology described in Patent Document 1, the amount of change in the PCV pressure sensor value is small even in a normal state where no abnormality occurs in the blow-by gas passage, so that the amount of change in the PCV pressure sensor value is unlikely to differ between when the blow-by gas passage is in a normal state and when a leakage abnormality occurs. Therefore, there is a problem that an abnormality in the blow-by gas passage may be erroneously diagnosed during such a stagnation period.

[0006] The present disclosure has been made to solve such problems, and has an object to provide an abnormality diagnosis device for an internal combustion engine that improves the accuracy of abnormality diagnosis of a blow-by gas treatment device. [Means for solving the problem]

[0007] An abnormality diagnosis device for an internal combustion engine according to one embodiment is an abnormality diagnosis device for an internal combustion engine with a turbocharger, in which the internal combustion engine has a blow-by gas passage that communicates with an intake passage upstream of a compressor of the turbocharger and through which blow-by gas leaked from a combustion chamber into a crankcase flows, a PCV pressure sensor that detects the pressure in the blow-by gas passage, and a supercharging pressure sensor that detects the pressure in the intake passage downstream of the compressor, and the abnormality diagnosis device detects a P The system includes a change response value derivation unit that derives a change response value corresponding to an amount of change in the CV pressure sensor value, a parameter derivation unit that derives a judgment parameter by accumulating a plurality of change response values, and a leakage abnormality diagnosis unit that diagnoses that an abnormality has occurred in the blow-by gas passage when the judgment parameter is less than a parameter threshold value, and the parameter derivation unit derives the judgment parameter by accumulating the derived change response value when the boost pressure sensor value detected by the boost pressure sensor is outside a predetermined judgment pressure range near atmospheric pressure and the intake air amount is changing during a specified monitoring interval. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide an abnormality diagnosis device for an internal combustion engine that improves the accuracy of abnormality diagnosis of a blow-by gas treatment device. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing an outline of an internal combustion engine equipped with an abnormality diagnostic device according to a first embodiment. [Diagram 2] 1 is a block diagram showing a configuration of an abnormality diagnostic device according to a first embodiment. [Diagram 3] 4 is a graph showing the relationship between the intake air amount and the PCV pressure sensor value. [Figure 4] 10 is a flowchart illustrating a process for diagnosing whether or not a clogging abnormality has occurred. [Diagram 5] 10 is a flowchart illustrating a process flow when diagnosing whether or not a leakage abnormality has occurred. [Figure 6] 6 is a timing chart showing a transition of the PCV pressure sensor value for explaining a change response value. [Figure 7] 4 is a map showing the relationship between the intake air amount and the determined increase amount. [Figure 8] 5 is a timing chart for diagnosing whether or not a leakage abnormality has occurred while the vehicle is running. [Figure 9] 5 is a timing chart showing a transition of the PCV pressure sensor value accompanying switching between a non-supercharging region and a supercharging region. [Figure 10] FIG. 11 is a block diagram showing a configuration of a change correspondence value deriving unit in the abnormality diagnostic device according to the second embodiment. [Figure 11] 6 is a timing chart showing a transition of the PCV pressure sensor value for explaining a change response value. [Figure 12] 10 is a flowchart illustrating a process flow when the abnormality diagnostic device according to the second embodiment derives a determination parameter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] First embodiment Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In addition, in order to clarify the description, the following description and drawings are appropriately simplified. What is shown in the drawings is only a part of the whole, and in reality, many other configurations that are not shown are included. Furthermore, in the following description, the same or equivalent elements are given the same reference numerals, and duplicated descriptions are omitted.

[0011] First, referring to Fig. 1, an overview of an internal combustion engine 10 equipped with an internal combustion engine abnormality diagnosis device (abnormality diagnosis device 50) according to this embodiment will be described. Fig. 1 is a diagram showing an overview of an internal combustion engine equipped with an abnormality diagnosis device according to the first embodiment. As shown in Fig. 1, the internal combustion engine 10 is an on-vehicle internal combustion engine having a plurality of cylinders 17, an injector that injects fuel into each cylinder 17, an intake passage 24 for supplying intake air to each cylinder 17, an exhaust passage 25 for discharging exhaust gas from each cylinder 17, and an exhaust turbine type supercharger 11 that supercharges the intake air flowing through the intake passage 24. The supercharger 11 is configured to include a turbine 111 and a compressor 112.

[0012] The internal combustion engine 10 has a cylinder block 12, a crankcase 13, an oil pan 15, a cylinder head 16, and a head cover 18. The crankcase 13 is attached to the lower part of the cylinder block 12, and a crankshaft 14 is housed within the crankcase 13. The oil pan 15 is attached to the lower part of the crankcase 13, and oil circulating within the internal combustion engine 10 is stored within the oil pan 15.

[0013] On the other hand, a cylinder head 16 is attached to the upper part of the cylinder block 12, and a plurality of cylinders 17 are defined by the cylinder block 12 and the cylinder head 16. Note that only one cylinder 17 is shown in Fig. 1. A head cover 18 is attached to the upper part of the cylinder head 16.

[0014] A piston 19 is housed in each cylinder 17, and each piston 19 is connected to the crankshaft 14 via a connecting rod 20. The reciprocating motion of each piston 19 in the cylinder 17 causes the crankshaft 14 to rotate.

[0015] The internal combustion engine 10 is provided with a communication passage 21 that communicates the space defined by the cylinder head 16 and the head cover 18 with the inside of the crankcase 13. The communication passage 21 is formed to straddle the cylinder block 12 and the cylinder head 16, with one end opening toward the inside of the crankcase 13 and the other end opening toward the inside of the head cover 18. Therefore, blow-by gas leaking from a combustion chamber 22 defined in the cylinder 17 into the crankcase 13 flows through the communication passage 21 into the space defined by the cylinder head 16 and the head cover 18. In other words, this space corresponds to an accumulation section 23 in which the blow-by gas accumulates.

[0016] A separator 40 that separates oil contained in the blow-by gas is provided in the communication passage 21. The separator 40 is disposed inside the head cover 18. The separator 40 is also connected to the intake manifold 29 of the intake passage 24 by a PCV passage 41.

[0017] An intake passage 24 is connected to the cylinder head 16 via an intake port, and an exhaust passage 25 is connected to the cylinder head 16 via an exhaust port. A turbine 111 is provided in the exhaust passage 25. A compressor 112 is connected to the turbine 111 so as to be rotatable together with the intake passage 24. The turbocharger 11 supercharges the intake air in the intake passage 24 by rotating the turbine 111 with exhaust gas flowing through the exhaust passage 25, thereby rotating the compressor 112 together with the turbine 111.

[0018] An air cleaner 26 is provided in the intake passage 24 upstream of the compressor 112. An intercooler 27 is provided in the intake passage 24 downstream of the compressor 112. A throttle valve 28 is provided in the intake passage 24 downstream of the intercooler 27. An intake manifold 29 is provided in the intake passage 24 downstream of the throttle valve 28. The intake manifold 29 is connected to the cylinder head 16 via an intake port, and is connected to a separator 40 via a PCV passage 41.

[0019] A supercharging pressure sensor 291 is connected to the intake manifold 29. The supercharging pressure sensor 291 is a sensor that detects the pressure (supercharging pressure) in the intake passage 24 downstream of the compressor 112. The supercharging pressure sensor 291 is a sensor that detects the pressure in the intake manifold 29 as a supercharging pressure sensor value PSUP, and outputs a signal corresponding to the detected supercharging pressure sensor value PSUP to the abnormality diagnosis device 50 as a detection signal.

[0020] In a non-supercharging region where the pressure in the intake passage 24 downstream of the compressor 112 is lower than the pressure in the intake passage 24 upstream of the compressor 112, the supercharging pressure sensor value PSUP is low. In a supercharging region where the pressure in the intake passage 24 downstream of the compressor 112 is higher than the pressure in the intake passage 24 upstream of the compressor 112, the supercharging pressure sensor value PSUP is high. Note that the supercharging pressure sensor 291 may be a sensor that detects absolute pressure, which is a relative pressure based on an absolute vacuum, or a sensor that detects gauge pressure, which is a relative pressure based on atmospheric pressure PHAC.

[0021] The intake air that flows through the intake passage 24 is introduced into the combustion chamber 22 via the intake port. An air-fuel mixture containing the intake air and fuel is burned in the combustion chamber 22. Exhaust gas generated in the combustion chamber 22 by the combustion of the air-fuel mixture is discharged to the exhaust passage 25 via the exhaust port.

[0022] The internal combustion engine 10 is equipped with a blow-by gas processing device 30 that returns blow-by gas leaked from the combustion chamber 22 into the crankcase 13 to the intake passage 24. Here, the intake passage 24 upstream of the compressor 112 and downstream of the air cleaner 26 (the portion between the compressor 112 and the air cleaner 26) is referred to as an upstream intake passage 241. The blow-by gas processing device 30 includes a blow-by gas passage 31 that connects the accumulation section 23 and the upstream intake passage 241, a PCV pressure sensor 35 that detects the pressure in the blow-by gas passage 31, and a PCV (Positive Crankcase Ventilation) valve 42 that opens and closes communication between the separator 40 and the intake manifold 29.

[0023] The blow-by gas passage 31 is configured to allow the blow-by gas leaked into the crankcase 13 to flow to the upstream intake passage 241. The PCV pressure sensor 35 is a sensor that detects the pressure in the blow-by gas passage 31 as a PCV pressure sensor value PCVS, and outputs a signal corresponding to the detected PCV pressure sensor value PCVS to the abnormality diagnosis device 50 as a detection signal.

[0024] The blow-by gas passage 31 has a joint 32 attached to the head cover 18, and a blow-by gas pipe 33 having one end connected to the tip of the joint 32 and the other end connected to the upstream intake passage 241. The base end of the joint 32 opens toward the accumulation section 23. The blow-by gas passage 31 communicates between the accumulation section 23 and the upstream intake passage 241. A PCV pressure sensor 35 is connected to the joint 32. That is, the PCV pressure sensor value PCVS detected by the PCV pressure sensor 35 is the pressure inside the joint 32. The PCV pressure sensor 35 may be a sensor that detects absolute pressure, or a sensor that detects gauge pressure.

[0025] The PCV valve 42 is provided in a PCV passage 41 between the intake manifold 29 and the separator 40. The PCV passage 41 allows the blow-by gas leaked into the crankcase 13 to flow to the intake manifold 29. The PCV valve 42 opens when the pressure in the intake manifold 29 is lower than the pressure in the separator 40 to communicate with the intake manifold 29. The PCV valve 42 also closes when the pressure in the intake manifold 29 is higher than the pressure in the separator 40 to block communication between the separator 40 and the intake manifold 29. In this way, the PCV valve 42 adjusts the flow rate of the blow-by gas passing through it and prevents the blow-by gas from flowing back into the separator 40.

[0026] In a non-supercharging region where supercharging by the supercharger 11 is not performed, the blow-by gas leaked into the crankcase 13 is returned to the intake passage 24 via the PCV valve 42. In detail, when the internal combustion engine 10 is operated in a non-supercharging state, negative pressure is generated in the intake manifold 29, the PCV valve 42 is opened, and the blow-by gas in the separator 40 passes through the PCV passage 41 and is returned to the intake passage 24. At this time, the blow-by gas in the accumulation section 23 and the crankcase 13 is drawn into the separator 40. When the blow-by gas passes through the PCV passage 41 and is sucked into the intake passage 24, the negative pressure generated in the accumulation section 23 and the crankcase 13 causes fresh air in the upstream intake passage 241 to pass through the blow-by gas passage 31 and be drawn into the accumulation section 23 and the crankcase 13. As a result, the accumulation section 23 and the crankcase 13 communicating with the accumulation section 23 can be ventilated with fresh air.

[0027] On the other hand, in the supercharging region where supercharging is performed by the supercharger 11, the blow-by gas leaked into the crankcase 13 is returned to the intake passage 24 via the blow-by gas passage 31. In detail, when the internal combustion engine 10 is operated in a supercharged state, the PCV valve 42 is closed as the pressure in the intake manifold 29 increases, and negative pressure is generated in the upstream intake passage 241, so that the blow-by gas in the blow-by gas passage 31 is returned to the intake passage 24. At this time, the blow-by gas in the crankcase 13 is drawn into the separator 40 and the accumulation section 23. As a result, the blow-by gas is accumulated in the separator 40 and the accumulation section 23 that is in communication with the separator 40.

[0028] Next, the abnormality diagnosis device 50 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the configuration of the abnormality diagnosis device according to the first embodiment. The abnormality diagnosis device 50 includes a so-called microcomputer equipped with, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a storage device. The CPU reads out programs and the like stored in the ROM, expands them in the RAM, and executes various processes according to the expanded programs, thereby executing various controls performed by the abnormality diagnosis device 50. The ROM stores various programs including a program for executing leakage abnormality diagnosis processing, various maps and various parameters for executing the leakage abnormality diagnosis processing, and the like.

[0029] As shown in FIG. 2, the abnormality diagnosis device 50 receives detection signals from various sensors necessary for controlling the internal combustion engine 10, such as the PCV pressure sensor 35 and the boost pressure sensor 291, as well as an atmospheric pressure sensor 71, an air flow meter 72, a battery voltage sensor 73, and a water temperature sensor 74. The atmospheric pressure sensor 71 detects the atmospheric pressure PHAC, which is the pressure around the internal combustion engine 10, and outputs a signal corresponding to the atmospheric pressure PHAC as a detection signal. The air flow meter 72 detects the intake air amount GA, which is the amount of intake air flowing through the intake passage 24, and outputs a signal corresponding to the intake air amount GA as a detection signal. The battery voltage sensor 73 detects a battery voltage Vbt, which is the voltage of the on-board battery, and outputs a signal corresponding to the battery voltage Vbt as a detection signal. The water temperature sensor 74 detects a water temperature Twt, which is the temperature of the cooling water for the internal combustion engine 10, and outputs a signal corresponding to the water temperature Twt as a detection signal.

[0030] The abnormality diagnosis device 50 diagnoses whether an abnormality has occurred in the blow-by gas processing device 30. Examples of abnormalities diagnosed by the abnormality diagnosis device 50 include clogging abnormality and leakage abnormality. The clogging abnormality is that a clogging occurs in a portion of the blow-by gas passage 31 that is closer to the upstream intake passage 241 than the connection portion of the PCV pressure sensor 35. If a clogging occurs in that portion, the blow-by gas accumulated in the accumulation portion 23 cannot be made to flow out to the intake passage 24 via the blow-by gas passage 31. The leakage abnormality is an abnormality that may cause the blow-by gas to 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 portion of the PCV pressure sensor 35. The leakage abnormality occurs when the blow-by gas pipe 33 comes off from the intake passage 24, the blow-by gas pipe 33 comes off from the joint 32, or the blow-by gas pipe 33 is damaged.

[0031] If the blow-by gas pipe 33 is disconnected from the intake passage 24, the blow-by gas leaks from the opening of the blow-by gas pipe 33 on the intake passage 24 side. If the blow-by gas pipe 33 is disconnected from the joint 32, the blow-by gas leaks from the joint 32. If the blow-by gas pipe 33 is damaged, the blow-by gas may leak from the damaged part to the outside. However, even if the blow-by gas passage 31 is damaged, the atmosphere may flow into the blow-by gas pipe 33 from the damaged part when the pressure in the accumulation section 23 is not so high.

[0032] When clogging occurs, communication between the accumulation portion 23 and the intake passage 24 via the blow-by gas passage 31 is blocked, so that the blow-by gas in the accumulation portion 23 is not returned to the intake passage 24 via the blow-by gas passage 31. Moreover, when the engine is operating, blow-by gas continues to be generated in the internal combustion engine 10. The amount of blow-by gas generated tends to increase as the intake air amount GA increases. Therefore, unlike when the blow-by gas passage 31 is in a normal state, even if the intake air amount GA increases and negative pressure is generated in the upstream intake passage 241, the pressure in the joint 32 does not decrease. More specifically, when the intake air amount GA is relatively large, the pressure in the joint 32 becomes higher than the atmospheric pressure PHAC. Conversely, when the intake air amount GA is relatively small, the pressure in the joint 32 becomes approximately equal to the atmospheric pressure PHAC.

[0033] If the blow-by gas piping 33 comes off the intake passage 24 or the joint 32, the inside of the joint 32 is opened to the atmosphere, so the pressure in the joint 32 is maintained near the atmospheric pressure PHAC regardless of the amount of intake air GA. If the blow-by gas passage 31 is damaged, the pressure in the joint 32 becomes closer to the atmospheric pressure PHAC, depending on the opening area of ​​the damaged part, because the inside of the blow-by gas passage 31 communicates with the atmosphere through the damaged part. In other words, when a leakage abnormality occurs, the amount of change in the pressure in the joint 32 with an increase in the amount of intake air GA becomes smaller than when no leakage abnormality occurs.

[0034] Therefore, the PCV pressure sensor value PCVS, which correlates with the pressure inside the joint 32, can be used to detect clogging abnormalities and leakage abnormalities.

[0035] Here, a state of the blow-by gas passage 31 where neither leakage nor clogging abnormality occurs is called a normal state. With reference to Fig. 3, the relationship between the intake air amount GA and the PCV pressure sensor value PCVS associated with switching between the non-supercharging region and the supercharging region when the blow-by gas passage 31 is in a normal state will be described. Fig. 3 is a graph showing the relationship between the intake air amount and the PCV pressure sensor value. Fig. 3 shows the transition of the PCV pressure sensor value PCVS associated with switching between the non-supercharging region where the intake air amount GA decreases and the supercharging region where the intake air amount GA increases.

[0036] As shown in Fig. 3, in a normal state without switching of the operating range, the flow direction of the blow-by gas (or fresh air) is constant, and the negative pressure generated increases with an increase in the intake air amount GA. Therefore, in the non-supercharging region, the flow rate of the fresh air passing through the blow-by gas passage 31 increases, and in the supercharging region, the flow rate of the blow-by gas passing through the blow-by gas passage 31 increases. That is, in a normal state, as the intake air amount GA increases, the PCV pressure sensor value PCVS decreases, and the change amount (decrease amount) of the PCV pressure sensor value PCVS increases.

[0037] However, when the non-supercharging region and the supercharging region are switched, the flow of the blow-by gas passing through the blow-by gas passage 31 is reversed, and the blow-by gas is likely to stagnate in the blow-by gas passage 31. Therefore, a stagnation period occurs during which the change amount of the PCV pressure sensor value PCVS is not likely to become large even if the intake air amount GA increases, compared to normal times. The stagnation period is a period from when supercharging by the supercharger 11 is started (stopped) until the flow direction of the blow-by gas passing through the blow-by gas passage 31 (PCV pressure sensor 35) becomes constant. During this stagnation period, the change amount of the PCV pressure sensor value PCVS is unlikely to differ between when the blow-by gas passage 31 is in a normal state and when a leakage abnormality occurs. Therefore, when performing an abnormality diagnosis of the blow-by gas device based on the PCV pressure sensor value PCVS, it is preferable not to target the stagnation period for the abnormality diagnosis.

[0038] Therefore, the abnormality diagnosis device 50 according to the present embodiment estimates the stagnation period that occurs with the switching of the operating range, and does not detect an abnormality in the blow-by gas passage 31 during the estimated stagnation period. This makes it possible to suppress erroneous diagnosis of an abnormality in the blow-by gas passage 31 during the stagnation period, and improve the accuracy of the abnormality diagnosis of the blow-by gas processing device 30.

[0039] As shown in FIG. 2, the abnormality diagnosis device 50 has, as functional units for diagnosing whether or not an abnormality has occurred in the blow-by gas treatment device 30, an increase determination unit 51, a clogging abnormality diagnosis unit 52, a change response value derivation unit 53, a parameter derivation unit 54, and a leakage abnormality diagnosis unit 55.

[0040] The increase determination unit 51 determines, based on the PCV pressure sensor value PCVS, whether or not increasing the intake air amount GA will increase the pressure in the blow-by gas passage 31. The details of this determination will be described later.

[0041] The clogging abnormality diagnosis unit 52 diagnoses that a clogging abnormality has occurred when the increase determination unit 51 determines that the pressure in the blow-by gas passage 31 will increase if the intake air amount GA is increased in a supercharged state.

[0042] When the intake air amount GA is changing and the PCV pressure sensor value PCVS is a negative pressure relative to the atmospheric pressure PHAC, the change response value derivation unit 53 derives a value corresponding to the amount of change in the PCV pressure sensor value PCVS during a predetermined monitoring interval PRD as a change response value X. The derivation process of the change response value X will be described later.

[0043] In addition, in the case of the PCV pressure sensor 35 that detects absolute pressure, the PCV pressure sensor 35 has a temperature characteristic. In addition, when the vehicle is running by engine operation, the atmospheric pressure PHAC may change during the monitoring section PRD. Therefore, when deriving the change response value X, the length of the monitoring section PRD is set so that the degree to which the influence of the temperature characteristic and the influence of the change in the atmospheric pressure PHAC are reflected in the change response value X can be within an acceptable range.

[0044] The parameter derivation unit 54 derives the determination parameter Z based on the change response value X derived by the change response value derivation unit 53. In this embodiment, the parameter derivation unit 54 derives an integrated value of the change response value X of a preset predetermined number NTh as the determination parameter Z. In addition, in this embodiment, the parameter derivation unit 54 derives the determination parameter Z by integrating the change response value X derived when the supercharging pressure sensor value PSUP is not near the atmospheric pressure PHAC and the intake air amount GA is changing.

[0045] The leakage abnormality diagnosis unit 55 executes a leakage abnormality diagnosis process for diagnosing whether or not a leakage abnormality has occurred, based on the judgment parameter Z derived by the parameter derivation unit 54. Specifically, the leakage abnormality diagnosis unit 55 diagnoses that an abnormality has occurred in the blow-by gas passage 31 when the judgment parameter Z is less than the parameter threshold value ZTh.

[0046] Next, the flow of processing when diagnosing whether or not a clogging abnormality has occurred will be described with reference to Fig. 4. Fig. 4 is a flowchart illustrating the flow of processing when diagnosing whether or not a clogging abnormality has occurred. The series of processing shown in Fig. 4 is repeatedly executed while the engine is operating.

[0047] In the first step S11, the increase determination unit 51 determines whether the intake air amount GA is equal to or greater than the supercharging determination intake air amount GATh1. When a clogging abnormality occurs and the intake air amount GA is relatively small, the pressure in the joint 32, which correlates with the PCV pressure sensor value PCVS, is approximately equal to the atmospheric pressure PHAC. In other words, the influence of the clogging abnormality on the PCV pressure sensor value PCVS is not large. Therefore, the supercharging determination intake air amount GATh1 is set to an intake air amount GA that cannot be achieved in a supercharged state.

[0048] If the intake air amount GA is less than the supercharging judgment intake air amount GATh1 (S11: NO), the process is returned. In other words, a diagnosis of whether or not a clogging abnormality has occurred is not performed. On the other hand, if the intake air amount GA is equal to or greater than the supercharging judgment intake air amount GATh1 (S11: YES), the process proceeds to the next step S12. In step S12, the increase determination unit 51 determines whether or not the PCV pressure sensor value PCVS is higher than the atmospheric pressure PHAC. If the PCV pressure sensor value PCVS is higher than the atmospheric pressure PHAC, increasing the intake air amount GA increases the pressure in the joint 32. On the other hand, if the PCV pressure sensor value PCVS is equal to or less than the atmospheric pressure PHAC, there is a possibility that the pressure in the joint 32 will not increase even if the intake air amount GA is increased.

[0049] Therefore, when the PCV pressure sensor value PCVS is higher than the atmospheric pressure PHAC (S12: YES), the process proceeds to the next step S13. In step S13, the clogging abnormality diagnosis unit 52 sets the clogging abnormality diagnosis flag FLG to ON. That is, when the PCV pressure sensor value PCVS is higher than the atmospheric pressure PHAC, it is determined that the pressure inside the joint 32 will increase if the intake air amount GA is increased while supercharging is being performed by the supercharger 11, and therefore a diagnosis is made that a clogging abnormality has occurred. Then, the process returns to step S11 (RETURN).

[0050] On the other hand, in step S12, if the PCV pressure sensor value PCVS is equal to or lower than the atmospheric pressure PHAC (S12: NO), the process proceeds to the next step S14. In step S14, the clogging abnormality diagnosis unit 52 sets the clogging abnormality diagnosis flag FLG to OFF. That is, it is not diagnosed that a clogging abnormality has occurred. Then, the process returns to step S11 (RETURN).

[0051] Next, the flow of processing when diagnosing whether or not a leakage abnormality has occurred will be described with reference to Fig. 5. Fig. 5 is a flowchart illustrating the flow of processing when diagnosing whether or not a leakage abnormality has occurred. A series of processing shown in Fig. 5 is repeatedly executed while the engine is operating.

[0052] In the first step S21, it is determined whether or not the execution conditions for executing the leakage abnormality diagnosis process are satisfied. In this embodiment, it is determined that the execution conditions are satisfied when all of the following conditions (1) to (3) are satisfied.

[0053] Condition (1): The clogging abnormality diagnosis flag FLG is set to OFF. Condition (2): The battery voltage Vbt is equal to or higher than the determination voltage VbtTh. Condition (3): The water temperature Twt is equal to or higher than the judgment water temperature TwtTh.

[0054] On the other hand, when at least one of the conditions (1) to (3) is not satisfied, it is not determined that the execution conditions are satisfied. When the battery voltage Vbt is lower than the determination voltage VbtTh, a sufficiently high voltage may not be applied to the sensor used for diagnosis. On the other hand, when the water temperature Twt is lower than the determination water temperature TwtTh, clogging due to freezing may occur in the blow-by gas passage 31.

[0055] If it is not determined that the execution condition is satisfied (S21: NO), the process returns to the original state (RETURN). In other words, a diagnosis as to whether a leakage abnormality has occurred is not performed. On the other hand, if it is determined that the execution condition is satisfied (S21: YES), the process proceeds to the next step S22.

[0056] In step S22, it is determined whether the intake air amount GA is equal to or greater than a second determination intake air amount GATh2. The second determination intake air amount GATh2 is set to a value that causes a difference in the PCV pressure sensor value PCVS in the supercharging region between when a leakage abnormality occurs and when the blow-by gas passage 31 is in a normal state.

[0057] If the intake air amount GA is less than the second judgment intake air amount GATh2 (S22: NO), the process proceeds to the next step S23. In step S23, a measurement counter CNT and a change correspondence value X, which will be described later, are reset to "0 (zero)". Then, the process returns to step S21 (RETURN). On the other hand, if the intake air amount GA is equal to or greater than the second judgment intake air amount GATh2 in step S22 (S22: YES), the change correspondence value derivation unit 53 executes the derivation process of the change correspondence value X (steps S24 to S27).

[0058] In the derivation process of the change correspondence value X, in step S24, the measurement counter CNT is incremented by "1". The measurement counter CNT corresponds to the elapsed time since the derivation process of the change correspondence value X was started. In the next step S25, a PCV pressure decrease amount ΔPCVS, which is the decrease amount of the PCV pressure sensor value PCVS, is calculated. That is, the PCV pressure sensor value PCVS at the start of the current monitoring section PRD is set as the reference value PCVSb. Then, when the PCV pressure sensor value PCVS at the current time is equal to or less than the reference value PCVSb, the difference between the PCV pressure sensor value PCVS at the current time and the reference value PCVSb is calculated as the PCV pressure decrease amount ΔPCVS. On the other hand, when the PCV pressure sensor value PCVS at the current time is higher than the reference value PCVSb, "0 (zero)" is derived as the PCV pressure decrease amount ΔPCVS.

[0059] Next, in step S26, the sum of the current value of the change response value X and the PCV pressure decrease amount ΔPCVS is calculated as the latest value of the change response value X. Next, in step S27, it is determined whether or not the measurement counter CNT is equal to or greater than the determination counter CNTTh. The determination counter CNTTh is a criterion for determining whether or not the monitoring section PRD has ended, and is set appropriately depending on the model of the internal combustion engine 10 and the type of the PCV pressure sensor 35. For example, by setting a short time of about several hundred ms as the determination counter CNTTh, it is possible to improve the accuracy of diagnosis.

[0060] If the measurement counter CNT is less than the determination counter CNTTh (S27: NO), the monitoring section PRD has not yet ended, and the process returns to step S21 (RETURN). That is, the derivation process of the change correspondence value X is not ended. On the other hand, if the measurement counter CNT is equal to or greater than the determination counter CNTTh (S27: YES), the monitoring section PRD has ended, and the derivation process of the change correspondence value X is ended. That is, the change correspondence value X is equal to the integrated value of the PCV pressure decrease amount ΔPCVS during one monitoring section PRD. Then, the process proceeds to the next step S28.

[0061] FIG. 6 shows an example of calculation of the change response value X. FIG. 6 is a timing chart showing the transition of the PCV pressure sensor value to explain the change response value. In the example shown in FIG. 6, the period from timing t11 to timing t12 is one monitoring section PRD. Therefore, the PCV pressure sensor value PCVS at timing t11 is the reference value PCVSb. In the example shown in FIG. 6, the PCV pressure sensor value PCVS continues to decrease after timing t11. Therefore, the area of ​​the hatched region in FIG. 6 corresponds to the change response value X. Therefore, the greater the decrease in the PCV pressure sensor value PCVS in the monitoring section PRD, the greater the change response value X is likely to be.

[0062] Returning to FIG. 5, in step S28, an increase amount ΔGA of the intake air amount GA during the monitoring section PRD is calculated. The increase amount ΔGA is calculated by subtracting the intake air amount GA at the start of the monitoring section PRD from the intake air amount GA at the end of the monitoring section PRD. Therefore, when the intake air amount GA has increased during the monitoring section PRD, the increase amount ΔGA is positive. In the next step S29, it is determined whether the calculated increase amount ΔGA is equal to or greater than the judgment increase amount ΔGATh. A value corresponding to the intake air amount GA at the start of the monitoring section PRD is set as the judgment increase amount ΔGATh. For example, the judgment increase amount ΔGATh is set using the map shown in FIG. 7.

[0063] Fig. 7 is a map showing the relationship between the intake air amount and the judged increase amount. The map shown in Fig. 7 shows the relationship between the judged increase amount ΔGATh and the intake air amount GA at the start of the monitoring section PRD. As shown in Fig. 7, the judged increase amount ΔGATh is set so that the smaller the intake air amount GA at the start of the monitoring section PRD is, the larger the value becomes.

[0064] Here, in a situation where the intake air amount GA is small at the start of the monitoring section PRD, the smaller the change in the intake air amount GA, the less likely it is that the change in the PCV pressure sensor value PCVS will differ between a case where the blow-by gas passage 31 is in a normal state and a case where a leakage abnormality has occurred. Therefore, the smaller the intake air amount GA at the start of the monitoring section PRD, the larger the judgment increase amount ΔGATh is set.

[0065] 5, in step S29, if the increase amount ΔGA is less than the judged increase amount ΔGATh (S29: NO), the process proceeds to the above-mentioned step S23. On the other hand, if the increase amount ΔGA is equal to or greater than the judged increase amount ΔGATh (S29: YES), the process proceeds to the next step S30.

[0066] In step S30, it is determined whether or not the supercharging pressure sensor value PSUP during the monitoring section PRD is outside a preset judgment pressure range R around the atmospheric pressure PHAC. The judgment pressure range R is a criterion for determining whether or not a stagnation period exists during the monitoring section PRD. As the judgment pressure range R, a range including a value corresponding to the supercharging pressure around the atmospheric pressure PHAC that may result in a stagnation period is set. The judgment pressure range R is appropriately set according to the type of the internal combustion engine 10. For example, it is preferable to set the judgment pressure range R to a range of about "atmospheric pressure PHAC±5 to 10 kPa". The judgment pressure range R is set based on data previously obtained by experiments or the like so that the degree to which the influence of the temperature characteristics of the supercharging pressure sensor 291 and the influence of the change in the atmospheric pressure PHAC are reflected in the stagnation period can be within an allowable range.

[0067] In step S30, if the supercharging pressure sensor value PSUP is within the determination pressure range R (S30: NO), the process proceeds to the above-mentioned step S23. On the other hand, if the supercharging pressure sensor value PSUP is outside the determination pressure range R (S30: YES), the process proceeds to the next step S31.

[0068] In step S31, the parameter derivation unit 54 increments the number of accumulations N by "1." Subsequently, in step S32, the parameter derivation unit 54 calculates the sum of the decision parameter Z and the change correspondence value X as the latest value of the decision parameter Z.

[0069] In the next step S33, it is determined whether the cumulative number N is equal to or greater than a predetermined number NTh. The predetermined number NTh is set appropriately depending on the type of the internal combustion engine 10. For example, it is preferable to set the predetermined number NTh to about 10 times. If the cumulative number N is less than the predetermined number NTh (S33: NO), the calculation of the judgment parameter Z has not yet been completed, and the process proceeds to the above-mentioned step S23. On the other hand, if the cumulative number N is equal to or greater than the predetermined number NTh (S33: YES), the calculation of the judgment parameter Z has been completed, and the leakage abnormality diagnosis unit 55 executes the leakage abnormality diagnosis process (steps S34 to S36). That is, the cumulative value of the change correspondence value X derived when the supercharging pressure sensor value PSUP is outside the judgment pressure range R and the increase amount ΔGA is equal to or greater than the judgment increase amount ΔGATh is calculated as the judgment parameter Z.

[0070] In the leakage abnormality diagnosis process, in step S34, it is determined whether the judgment parameter Z is equal to or greater than a parameter threshold value ZTh. The parameter threshold value ZTh is set as a criterion for determining whether the blow-by gas passage 31 is in a normal state based on the judgment parameter Z. If the judgment parameter Z is equal to or greater than the parameter threshold value ZTh (S34: YES), it can be determined that the judgment parameter Z is large, and the process proceeds to the next step S35. In step S35, it is determined that the blow-by gas passage 31 is in a normal state. Then, the leakage abnormality diagnosis process is ended, and the process proceeds to step S37.

[0071] On the other hand, in step S34, if the judgment parameter Z is less than the parameter threshold value ZTh (S34: NO), it can be determined that the judgment parameter Z is not large, and the process proceeds to the next step S36. In step S36, it is diagnosed that a leakage abnormality has occurred in the blow-by gas passage 31. Then, the leakage abnormality diagnosis process is ended, and the process proceeds to step S37.

[0072] In step S37, a reset process is executed. In the reset process, the measurement counter CNT, the change correspondence value X, the number of integrations N, and the judgment parameter Z are each reset to "0 (zero)." After that, the process returns to step S21.

[0073] Next, the operation and effect of this embodiment will be described with reference to Fig. 8. In Fig. 8, the timing chart showing the transition of the PCV pressure sensor value PCVS shows the transition of the PCV pressure sensor value PCVS when the blow-by gas passage 31 is in a normal state with a solid line, and the transition of the PCV pressure sensor value PCVS when a leakage abnormality occurs with a dashed line. In Fig. 8, the timing chart showing the transition of the determination parameter Z shows the transition of the determination parameter Z when the blow-by gas passage 31 is in a normal state with a solid line, and the transition of the determination parameter Z when a leakage abnormality occurs with a dashed line.

[0074] When the vehicle is running, the intake air is pressurized in the internal combustion engine 10 by driving the supercharger 11. Then, at timing t1, the intake air amount GA becomes equal to or larger than the second judgment intake air amount GATh2, and the derivation process of the change correspondence value X is started. The derivation process is ended at timing t2. The increase amount ΔGA of the intake air amount GA between timing t1 and timing t2 becomes equal to or larger than the judgment increase amount ΔGATh. In addition, there is a period between timing t1 and timing t2 during which the supercharging pressure sensor value PSUP is within the judgment pressure range R. Therefore, if the section from timing t1 to timing t2 is set as a monitoring section PRD1, the judgment parameter Z is updated by the change correspondence value X1 derived when the supercharging pressure sensor value PSUP is outside the judgment pressure range R during the monitoring section PRD1. Note that the hatched area in FIG. 8 corresponds to the judgment pressure range R.

[0075] When the intake air amount GA is increased in the monitoring section PRD1, negative pressure is generated in the upstream intake passage 241 and positive pressure is generated in the intake manifold 29. When the blow-by gas passage 31 is in a normal state, the blow-by gas in the blow-by gas passage 31 is sucked into the intake passage 24. Therefore, the PCV pressure sensor value PCVS becomes low. At this time, the supercharging pressure sensor value PSUP becomes high across the atmospheric pressure PHAC. On the other hand, when a leakage abnormality occurs, the inside of the blow-by gas passage 31 is in communication with the outside. Therefore, even if negative pressure is generated in the upstream intake passage 241, the PCV pressure sensor value PCVS is less likely to become low compared to when the blow-by gas passage 31 is in a normal state. Therefore, when a leakage abnormality occurs, the change response value X1 is less likely to become large compared to when the blow-by gas passage 31 is in a normal state.

[0076] During the monitoring section PRD1, when the supercharging pressure sensor value PSUP is within the judgment pressure range R, it is estimated that the period is stagnant. Therefore, even if the derivation process of the change response value X is executed, the judgment parameter Z is not updated by the change response value X derived at this time. Moreover, since the intake air amount GA is decreasing from the timing t2, that is, the supercharging pressure is decreasing, even if the derivation process of the change response value X is executed, the judgment parameter Z is not updated by the change response value X derived at this time. Note that, when the intake air amount GA is decreasing, the negative pressure generated in the upstream intake passage 241 becomes smaller, so that the PCV pressure sensor value PCVS approaches the atmospheric pressure PHAC from the timing t2. Moreover, from the timing t2, the supercharging pressure sensor value PSUP becomes lower by straddling the atmospheric pressure PHAC.

[0077] From timing t3, the intake air amount GA increases again due to the drive of the supercharger 11. Then, at timing t4, the intake air amount GA becomes equal to or greater than the second judgment intake air amount GATh2, and the derivation process of the change response value X is started. The derivation process ends at timing t5. The increase amount ΔGA of the intake air amount GA between timing t4 and timing t5 becomes equal to or greater than the judgment increase amount ΔGATh. Also, between timing t4 and timing t5, there is a period during which the supercharging pressure sensor value PSUP is within the judgment pressure range R. Therefore, if the section from timing t4 to timing t5 is set as the monitoring section PRD2, the judgment parameter Z is updated by the change response value X2 derived when the supercharging pressure sensor value PSUP is outside the judgment pressure range R during the monitoring section PRD2.

[0078] In the example shown in FIG. 8, at the timing t5 when the monitoring section PRD2 ends, the intake air amount GA is greater than the second judgment intake air amount GATh2, and the intake air amount GA increases even after the timing t5. Therefore, the derivation process of the change correspondence value X is started at the timing t5. The derivation process ends at the timing t6. The increase amount ΔGA of the intake air amount GA between the timing t5 and the timing t6 becomes equal to or greater than the judgment increase amount ΔGATh. Also, there is no period between the timing t5 and the timing t6 during which the supercharging pressure sensor value PSUP is within the judgment pressure range R. Therefore, if the section from the timing t5 to the timing t6 is set as the monitoring section PRD3, the judgment parameter Z is updated by the change correspondence value X3 derived during the monitoring section PRD3.

[0079] 8, the cumulative number N reaches a predetermined number NTh at timing t6. Therefore, the leakage abnormality diagnosis process is executed at timing t6. As shown by a solid line in the timing chart showing the transition of the determination parameter Z, when the determination parameter Z is equal to or greater than the parameter threshold value ZTh, it can be determined that the PCV pressure sensor value PCVS is decreasing in response to the decrease in pressure in the upstream intake passage 241 due to the drive of the turbocharger 11, and therefore the blow-by gas passage 31 is diagnosed as being in a normal state.

[0080] On the other hand, as shown by the dashed line in the timing chart showing the trend of the judgment parameter Z, when the judgment parameter Z is less than the parameter threshold value ZTh, it can be determined that the PCV pressure sensor value PCVS has not decreased significantly even if the pressure in the upstream intake passage 241 decreases due to the operation of the turbocharger 11, and therefore it is diagnosed that a leakage abnormality has occurred.

[0081] In other words, according to the abnormality diagnosis device 50 of this embodiment, by using the judgment parameter Z, it is possible to detect breakage of the blow-by gas piping 33, detachment of the blow-by gas piping 33 from the intake passage 24, and detachment of the blow-by gas piping 33 from the fitting 32.

[0082] Here, Fig. 9 is a timing chart showing the transition of the PCV pressure sensor value with the change of the operating range. In the timing chart showing the transition of the PCV pressure sensor value PCVS shown in Fig. 9, the transition of the PCV pressure sensor value PCVS during normal operation without the change of the operating range is shown by a solid line, and the transition of the PCV pressure sensor value PCVS when the operating range is changed is shown by a two-dot chain line.

[0083] As shown in FIG. 9, when the operating range is switched near the monitoring section PRD1, the monitoring section PRD1 includes a stagnation period. The PCV pressure sensor value PCVS during the stagnation period is closer to the atmospheric pressure PHAC than during normal operation, as in the case where a leakage abnormality occurs. That is, the change amount of the PCV pressure sensor value PCVS associated with an increase in the intake air amount GA during the monitoring section PRD1 becomes smaller, so that the change correspondence value X is unlikely to become large. Therefore, for example, when the leakage abnormality diagnosis process is executed using the determination parameter Z derived when the increase amount ΔGA satisfies only the condition that the increase amount ΔGA is equal to or larger than the determination increase amount ΔGATh, the determination parameter Z becomes less than the parameter threshold value ZTh. In this case, a diagnosis that a leakage abnormality occurs is made, which may lead to an erroneous diagnosis of an abnormality in the blow-by gas passage 31.

[0084] In contrast, in the abnormality diagnosis device 50 according to the present embodiment, when deriving the judgment parameter Z, the stagnation period is estimated by monitoring the supercharging pressure, and the judgment parameter Z is not calculated using the change correspondence value X derived during the stagnation period. This excludes the timing (stagnation period) at which the diagnostic accuracy decreases with the switching of the operating region between the non-supercharging region and the supercharging region from the target for abnormality detection, and as a result, erroneous diagnosis of an abnormality in the blow-by gas passage 31 can be suppressed.

[0085] In addition, in this embodiment, the following effects can be further obtained. (1-1) In this embodiment, a value corresponding to the amount of decrease in the PCV pressure sensor value PCVS within the monitoring section PRD is calculated as the change response value X, and an integrated value of the multiple change response values ​​X is calculated as the judgment parameter Z. The length of the monitoring section PRD is set in consideration of the temperature characteristics of the PCV pressure sensor 35 and the change in atmospheric pressure PHAC that accompanies vehicle travel.

[0086] The shorter the monitoring section PRD, the less likely it is that the temperature change amount of the PCV pressure sensor 35 during the monitoring section PRD will be large. Therefore, by shortening the monitoring section PRD, the influence of the temperature characteristics of the PCV pressure sensor 35 is less likely to be reflected in the change response value X.

[0087] A sensor that detects absolute pressure is preferably used as the PCV pressure sensor 35. Therefore, in a situation where the inside of the blow-by gas passage 31 is in communication with the atmosphere, when the vehicle is traveling on a slope, the atmospheric pressure PHAC changes, and the PCV pressure sensor value PCVS changes according to the change in the atmospheric pressure PHAC. Therefore, if the amount of change in the atmospheric pressure PHAC is large during one monitoring section PRD, the proportion of the amount of change in the PCV pressure sensor value PCVS caused by the change in the atmospheric pressure PHAC becomes large. That is, the influence of the change in the atmospheric pressure PHAC is easily reflected in the change correspondence value X. In this regard, in the present embodiment, the length of the monitoring section PRD is set to a length that takes into consideration the change in the atmospheric pressure PHAC accompanying the traveling of the vehicle. Therefore, even when the inside of the blow-by gas passage 31 is in communication with the atmosphere, the influence of the change in the atmospheric pressure PHAC is less likely to be reflected in the change correspondence value X.

[0088] The determination parameter Z is calculated by integrating a plurality of change correspondence values ​​X that do not largely reflect the influence of the temperature characteristics of the PCV pressure sensor 35 and the influence of the change in the atmospheric pressure PHAC. Therefore, the determination parameter Z can be calculated as a value that is not largely affected by the temperature characteristics of the PCV pressure sensor 35 and the change in the atmospheric pressure PHAC that accompanies vehicle running. By executing the leakage abnormality diagnosis process using such a determination parameter Z, it is possible to suppress a decrease in the accuracy of the diagnosis.

[0089] (1-2) In this embodiment, the integrated value of the decrease in the PCV pressure sensor value PCVS from the reference value PCVSb during the monitoring section PRD is calculated as the change response value X. Therefore, the difference in the change response value X between when the blow-by gas passage 31 is in a normal state and when a leakage abnormality occurs can be made large.

[0090] (1-3) In this embodiment, a clogging abnormality diagnosis process is also executed. In the clogging abnormality diagnosis process, when it is determined that the pressure in the blow-by gas passage 31 is higher than the atmospheric pressure PHAC while supercharging is being performed, it is diagnosed that a clogging abnormality has occurred. That is, according to this embodiment, it is also possible to detect that a clogging abnormality has occurred.

[0091] (1-4) Now consider a case where, when a clogging abnormality occurs, a judgment parameter Z is calculated and a leakage abnormality diagnosis process is executed using the judgment parameter Z. In this case, since the judgment parameter Z is less than the parameter threshold value ZTh, a diagnosis that a leakage abnormality has occurred is made. In this regard, in the present embodiment, when a diagnosis that a clogging abnormality has occurred is made, the leakage abnormality diagnosis process is not executed. Therefore, it is possible to prevent a misdiagnosis that a leakage abnormality has occurred when a clogging abnormality has occurred.

[0092] As described above, according to the abnormality diagnostic device 50 of this embodiment, the accuracy of abnormality diagnosis of the blow-by gas processing device 30 can be improved.

[0093] Embodiment 2 Next, an abnormality diagnosis device 50 according to a second embodiment will be described with reference to Fig. 10 to Fig. 12. The second embodiment differs from the first embodiment in terms of calculation of the change correspondence value X. Therefore, in the following description, the differences from the first embodiment will be mainly described, and the same reference numerals will be used to designate the same or corresponding members as those in the first embodiment, and duplicated description will be omitted.

[0094] Fig. 10 is a block diagram showing a configuration of a change correspondence value derivation unit in the abnormality diagnosis device according to the second embodiment. As shown in Fig. 10, the change correspondence value derivation unit 53 has a sensor value storage unit 53M that sequentially stores the PCV pressure sensor value PCVS during the monitoring section PRD. The sensor value storage unit 53M stores the PCV pressure sensor value PCVS at that time every time the measurement counter CNT is updated during the monitoring section PRD. That is, the change correspondence value derivation unit 53 can acquire multiple PCV pressure sensor values ​​PCVS during one monitoring section PRD.

[0095] In this embodiment, the change correspondence value derivation unit 53 executes the derivation process of the change correspondence value X when the intake air amount GA is increasing, as in the case of the above-mentioned embodiment 1. In this case, the change correspondence value derivation unit 53 stores the PCV pressure sensor value PCVS at that time in the sensor value storage unit 53M every time the measurement counter CNT is updated. When the measurement counter CNT becomes equal to or greater than the determination counter CNTTh, the change correspondence value derivation unit 53 ends the process of storing the PCV pressure sensor value PCVS in the sensor value storage unit 53M. Then, the change correspondence value derivation unit 53 sets the maximum value of the multiple PCV pressure sensor values ​​PCVS stored in the sensor value storage unit 53M as the reference value PCVSb. Next, the change correspondence value derivation unit 53 calculates the difference between the multiple PCV pressure sensor values ​​PCVS stored in the sensor value storage unit 53M and the reference value PCVSb, and calculates the integrated value of the multiple differences as the change correspondence value X. When the calculation of the change response value X is completed, the change response value derivation unit 53 erases the multiple PCV pressure sensor values ​​PCVS from the sensor value storage unit 53M, and then ends the derivation process.

[0096] FIG. 11 is a timing chart showing the transition of the PCV pressure sensor value to explain the change response value. In FIG. 11, the period from timing t31 to timing t32 is the monitoring section PRDA in which the intake air amount GA increases. When the intake air amount GA increases as in the monitoring section PRDA, the PCV pressure sensor value PCVS decreases in response to the increase in the intake air amount GA. Therefore, in the example shown in FIG. 12, the PCV pressure sensor value PCVS at timing t31, which is the start point of the monitoring section PRDA, is set as the reference value PCVSb. In this case, the area of ​​the hatched region in FIG. 11 corresponds to the change response value X in the monitoring section PRDA.

[0097] In this embodiment, the change correspondence value derivation unit 53 executes the derivation process of the change correspondence value X even when the intake air amount GA is decreasing. Even in this case, the change correspondence value derivation unit 53 stores the PCV pressure sensor value PCVS at that time in the sensor value storage unit 53M every time the measurement counter CNT is updated. When the measurement counter CNT becomes equal to or greater than the determination counter CNTTh, the change correspondence value derivation unit 53 ends the process of storing the PCV pressure sensor value PCVS in the sensor value storage unit 53M. Then, the change correspondence value derivation unit 53 sets the maximum value of the multiple PCV pressure sensor values ​​PCVS stored in the sensor value storage unit 53M as the reference value PCVSb. Next, the change correspondence value derivation unit 53 calculates the difference between the multiple PCV pressure sensor values ​​PCVS stored in the sensor value storage unit 53M and the reference value PCVSb, and calculates the integrated value of the multiple differences as the change correspondence value X. When the calculation of the change response value X is completed, the change response value derivation unit 53 erases the multiple PCV pressure sensor values ​​PCVS from the sensor value storage unit 53M, and then ends the derivation process.

[0098] In Fig. 11, the period from timing t33 ​​to timing t34 is the monitoring section PRDB in which the intake air amount GA decreases. When the intake air amount GA is decreasing as in the monitoring section PRDB, the PCV pressure sensor value PCVS increases in accordance with the decrease in the intake air amount GA. Therefore, in the example shown in Fig. 11, the PCV pressure sensor value PCVS at timing t34, which is the end point of the monitoring section PRDB, is set as the reference value PCVSb. In this case, the area of ​​the hatched region in Fig. 11 corresponds to the change correspondence value X in the monitoring section PRDB.

[0099] Next, a process flow from the completion of calculation of the change correspondence value X to the calculation of the judgment parameter Z will be described with reference to Fig. 12. The series of processes shown in Fig. 12 is started when the execution of the derivation process of the change correspondence value X by the change correspondence value derivation unit 53 is completed.

[0100] In the first step S41, the change amount ΔGAa of the intake air amount GA during the monitoring section PRD when the change correspondence value X is calculated is calculated. For example, the difference between the intake air amount GA at the start of the monitoring section PRD and the maximum value of the intake air amount GA during the monitoring section PRD is set as a first difference, and the difference between the intake air amount GA at the start of the monitoring section PRD and the minimum value of the intake air amount GA during the monitoring section PRD is set as a second difference. In this case, the larger of the first difference and the second difference is calculated as the change amount ΔGAa.

[0101] Next, in step S42, it is determined whether the change amount ΔGAa is equal to or greater than a reference change amount ΔGAaTh. The reference change amount ΔGAaTh is set to be larger as the intake air amount GA at the start of the monitoring period PRD is smaller, similar to the reference increase amount ΔGATh used in the first embodiment.

[0102] If the amount of change ΔGAa is less than the judged amount of change ΔGAaTh (S42: NO), the process proceeds to the next step S43. In step S43, the measurement counter CNT and the change corresponding value X are reset to "0 (zero)". Then, a series of processes is ended. On the other hand, in step S42, if the amount of change ΔGAa is equal to or greater than the judged amount of change ΔGAaTh (S42: YES), the process proceeds to the next step S44.

[0103] In step S44, it is determined whether or not the supercharging pressure sensor value PSUP during the monitoring section PRD is outside a preset determination pressure range R near the atmospheric pressure PHAC. In step S44, if the supercharging pressure sensor value PSUP is within the determination pressure range R (S44: NO), the process proceeds to the above-mentioned step S43. On the other hand, if the supercharging pressure sensor value PSUP is outside the determination pressure range R (S44: YES), the process proceeds to the next step S45. In step S45, the parameter derivation unit 54 calculates the sum of the determination parameter Z and the change correspondence value X as the latest value of the determination parameter Z.

[0104] Next, in step S46, the parameter derivation unit 54 increments the number of integrations N by "1". Then, in step S47, it is determined whether the number of integrations N is equal to or greater than a predetermined number NTh. If the number of integrations N is less than the predetermined number NTh (S47: NO), the calculation of the judgment parameter Z has not yet been completed, and the process proceeds to the above-mentioned step S43. On the other hand, if the number of integrations N is equal to or greater than the predetermined number NTh (S47: YES), the calculation of the judgment parameter Z has been completed, and the series of processes is terminated. That is, a value obtained by accumulating a plurality of change correspondence values ​​X is calculated as the judgment parameter Z. Thereafter, the leakage abnormality diagnosis process is executed using the judgment parameter Z.

[0105] In this embodiment, the following effects can be further obtained. (2-1) In this embodiment, the judgment parameter Z is calculated using not only the change response value X calculated when the intake air amount GA is increasing, but also the change response value X calculated when the intake air amount GA is decreasing. Therefore, compared to the case where the judgment parameter Z is derived only from the change response value X calculated when the intake air amount GA is increasing as in the above-mentioned first embodiment, it is possible to increase the number of opportunities to calculate the change response value X. In addition, by increasing the number of opportunities to calculate the change response value X, it is possible to shorten the period required to complete the derivation of the judgment parameter Z. Therefore, the leakage abnormality diagnosis process can be started early.

[0106] The present disclosure is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit and scope of the present disclosure. The above-described embodiments and the following modified examples can be combined with each other within the scope of technical compatibility.

[0107] The PCV pressure sensor 35 may be connected to the blow-by gas piping 33. Even in this case, if the blow-by gas piping 33 is damaged in a portion closer to the intake passage 24 than the connection portion of the PCV pressure sensor 35, or if the blow-by gas piping 33 becomes detached from the intake passage 24, it can be diagnosed that a leakage abnormality has occurred.

[0108] A cause of clogging in the blow-by gas pipe 33 is freezing in the blow-by gas pipe 33. That is, when the water temperature Twt is low, clogging abnormality due to freezing may occur, but when the water temperature Twt is high, clogging abnormality due to freezing does not occur. In the series of processes shown in FIG. 5, the execution condition of the leakage abnormality diagnosis process includes that the water temperature Twt is equal to or higher than the judgment water temperature TwtTh. When the judgment water temperature TwtTh is set as a value at which it can be determined that no freezing has occurred in the blow-by gas passage 31, the execution condition of the leakage abnormality diagnosis process does not need to include that the clogging abnormality diagnosis flag FLG is set to OFF. That is, the clogging abnormality diagnosis process does not need to be executed.

[0109] If a value corresponding to the amount of change in the PCV pressure sensor value PCVS during the monitoring section PRD can be derived as the change response value, a value different from the values ​​described in the above embodiments may be calculated as the change response value. For example, a trajectory length, which is the length of a line showing the change in the PCV pressure sensor value PCVS during the monitoring section PRD, may be derived as the change response value.

[0110] The calculation of the change response value X may be repeatedly executed until the elapsed time from the time when the execution condition for the leakage abnormality diagnosis process is satisfied reaches the judgment elapsed time, and the sum of all the change response values ​​X that satisfy the processing condition may be calculated as the judgment parameter Z. In this case, the parameter threshold value ZTh is varied according to the number of times N that the change response value X is accumulated when the judgment parameter Z is calculated. That is, the parameter threshold value ZTh is set to a larger value as the number of times N that the accumulation is performed increases.

[0111] An average value of a plurality of change correspondence values ​​X may be derived as the judgment parameter Z. Using such judgment parameter Z also makes it possible to diagnose whether or not a leakage abnormality has occurred.

[0112] In the above-mentioned first embodiment, the determination increment ΔGATh does not have to be variable. In the above-mentioned second embodiment, the determination change amount ΔGAaTh does not have to be variable. The position of the boost pressure sensor 291 is not limited to a position where it can detect the pressure inside the intake manifold 29, but may be any position where it can detect the pressure inside the intake passage 24 downstream of the compressor 112.

[0113] The amount of decrease in the PCV pressure sensor value PCVS in a period longer than the monitoring section PRD described in each of the above embodiments may be derived as the judgment parameter Z. Even in this case, although the accuracy of diagnosis is lower than in each of the above embodiments, it is possible to diagnose whether or not a leakage abnormality has occurred.

[0114] The blow-by gas passage 31 may be a passage having one end connected to the crankcase 13 and the other end connected to the upstream intake passage 241. In this case, the inside of the crankcase 13 corresponds to the accumulation section 23.

[0115] The internal combustion engine 10 may be equipped with an engine-driven supercharger 11. [Explanation of symbols]

[0116] 10 Internal combustion engine 11. Turbocharger 12 Cylinder block 13 Crankcase 14 Crankshaft 15 Oil pan 16 Cylinder head 17 cylinders 18 Head Cover 19 Piston 20 Connecting rod 21 Communication path 22 Combustion chamber 23 Storage section 24 Intake passage 25 Exhaust passage 26 Air cleaner 27 Intercooler 28 Throttle valve 29 Intake manifold 30 Blow-by gas treatment device 31 Blow-by gas passage 32 Joints 33 Blow-by gas piping 35 PCV pressure sensor 40 Separator 41 PCV passage 42 PCV valve 50 Abnormality diagnosis device 51 Increase judgment section 52 Clogging and abnormality diagnosis section 53 Change correspondence value derivation part 53M sensor value storage section 54 Parameter Derivation Section 55 Leakage abnormality diagnosis section 71 Atmospheric pressure sensor 72 Air flow meter 73 Battery Voltage Sensor 74 Water temperature sensor 111 Turbine 112 Compressor 241 Upstream intake passage 291 Boost pressure sensor

Claims

[Claim 1] An abnormality diagnosis device for an internal combustion engine with a turbocharger, The internal combustion engine includes: a blow-by gas passage communicating with an intake passage upstream of a compressor of the turbocharger and through which blow-by gas leaking from a combustion chamber into a crankcase flows; a PCV pressure sensor for detecting a pressure in the blow-by gas passage; a boost pressure sensor for detecting a pressure in the intake passage downstream of the compressor; having The abnormality diagnosis device includes: a change correspondence value derivation unit that derives a change correspondence value corresponding to an amount of change in the PCV pressure sensor value during a predetermined monitoring period when a PCV pressure sensor value, which is a pressure detected by the PCV pressure sensor, is a negative pressure lower than atmospheric pressure; a parameter derivation unit that derives a judgment parameter by integrating a plurality of the change correspondence values; a leakage abnormality diagnosis unit that diagnoses that an abnormality has occurred in the blow-by gas passage when the determination parameter is less than a parameter threshold value; having The parameter derivation unit deriving the judgment parameter by integrating the change corresponding value derived when the boost pressure sensor value detected by the boost pressure sensor is outside a preset judgment pressure range near atmospheric pressure and the intake air amount is changing during the predetermined monitoring period; An abnormality diagnosis device for internal combustion engines.

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