JP2018193875A - Abnormality detection device for internal combustion engine - Google Patents

Abstract

An abnormality detection device for an internal combustion engine capable of improving the detection accuracy of abnormality in PCV piping is provided. A control device 70 as an abnormality detection device for an internal combustion engine includes a throttle valve 31, an air flow meter 92 as a pulsation detection sensor, and a PCV pipe 40 for causing blow-by gas to flow from an engine body 10 to an intake passage. Applies to internal combustion engines. The control device 70 detects abnormality of the PCV pipe 40 from the engine body 10 or the intake passage based on the magnitude of the pulsation of the intake air flowing through the intake passage based on the output signal from the air flow meter 92. An abnormality detection unit 78 that performs processing is provided. The abnormality detection unit 78 performs an abnormality detection process based on the magnitude of intake pulsation when the opening of the throttle valve 31 is greater than or equal to a predetermined opening. [Selection] Figure 1

Description

  The present invention relates to an abnormality detection device for an internal combustion engine.

  The internal combustion engine described in Patent Document 1 is provided with a PCV pipe that communicates the intake downstream side of the intake passage with the crank chamber in the intake passage. The blow-by gas in the crank chamber flows into the intake passage through the PCV piping. The intake passage is also provided with an air flow meter disposed upstream of the throttle valve. Pulsation occurs in the intake passage because intake air and blow-by gas flow as the intake valve opens and closes. This pulsation is reduced when the PCV piping is clogged and the flow of blow-by gas is suppressed. In the abnormality detection device for an internal combustion engine described in Patent Document 1, it is determined that an abnormality has occurred in the PCV piping when the amplitude of the intake pulsation detected by the air flow meter is equal to or smaller than a determination value.

JP 2011-27073 A

  As described above, the pulsation generated in the intake passage is detected by the air flow meter arranged upstream of the throttle valve. That is, the intake pulsation in the intake passage caused by the opening and closing of the intake valve is transmitted from the intake downstream side to the intake upstream side. When the PCV pipe is disconnected from the engine main body or the intake passage of the internal combustion engine, the outside air flows into the intake passage from an opening on the engine main body side of the PCV pipe or a connection port with the PCV pipe in the intake passage. Due to such inflow of outside air, the intake pulsation in the intake passage caused by opening and closing of the intake valve is attenuated when transmitted to the upstream side of the intake air, and in this case also, the intake pulsation transmitted to the air flow meter is reduced. . Therefore, it is also possible to detect the disconnection of the PCV pipe by detecting this reduced pulsation with an air flow meter.

  Incidentally, a throttle valve is provided in the intake passage, and the transmission of pulsation in the intake passage depends on the opening of the throttle valve. When the opening of the throttle valve is small, the transmission of pulsation to the intake upstream side is suppressed, so the intake pulsation detected by the air flow meter is small. Therefore, in such a case, the magnitude of the intake pulsation detected by the air flow meter when the PCV pipe is connected to the intake passage and the intake air detected by the air flow meter when the PCV pipe is out of the intake passage. The difference from the magnitude of pulsation is reduced. Therefore, depending on the opening of the throttle valve, it may be difficult to determine whether the PCV piping is normal or abnormal. Therefore, there is a limit to improving the detection accuracy of PCV piping disconnection abnormality.

  An abnormality detection apparatus for an internal combustion engine for solving the above-described problems includes a throttle valve disposed in an intake passage of the internal combustion engine, a pulsation detection sensor disposed upstream of the throttle valve in the intake passage, and the internal combustion engine. A PCV pipe having one end connected to the engine body of the engine and the other end connected to the intake downstream side of the pulsation detection sensor in the intake passage, and for causing blow-by gas to flow from the engine body to the intake passage; And detecting the detachment of the PCV pipe from the engine body or the intake passage based on the magnitude of the pulsation of the intake air flowing through the intake passage based on the output signal from the pulsation detection sensor. An abnormality detection unit that performs an abnormality detection process that is a process to perform, the abnormality detection unit, the opening of the throttle valve is greater than or equal to a predetermined opening It performs the abnormality detection processing based on the magnitude of the pulsation in the state.

  According to the above configuration, based on the intake pulsation in a state where the opening of the throttle valve is equal to or greater than the predetermined opening, the detection processing of the PCV piping from the engine body or the intake passage, that is, the PCV piping abnormality detection processing is performed. . Therefore, intake pulsation in the intake passage is easy to be transmitted from the intake downstream side of the throttle valve to the intake upstream side, and when the PCV piping is not disconnected from the engine body and the intake passage, and when the PCV piping is disconnected from the engine body and the intake passage. It is possible to detect abnormality of the PCV piping based on the intake pulsation in a situation where a sufficient difference is likely to occur in the magnitude of the intake pulsation in the intake passage. Therefore, it is possible to improve detection accuracy of PCV piping abnormality by suppressing erroneous detection of normality and abnormality of PCV piping.

  In the abnormality detection apparatus for an internal combustion engine, when the abnormality detection process is performed by the abnormality detection unit, when the opening of the throttle valve is less than the predetermined opening, the opening of the throttle valve is opened. It is desirable to provide a throttle valve opening degree control unit that controls the angle more than 1 degree.

  In the above configuration, when the abnormality detection process is executed, if the opening degree of the throttle valve is less than the predetermined opening degree, the abnormality detection process is executed by controlling the opening degree of the throttle valve to be equal to or larger than the predetermined opening degree. Therefore, according to the above configuration, the detection frequency of the abnormality detection process can be increased.

  In the abnormality detection apparatus for an internal combustion engine, an EGR passage in which the internal combustion engine communicates an exhaust passage of the internal combustion engine and an intake downstream side of the throttle valve in the intake passage, and an EGR valve disposed in the EGR passage The abnormality detection device includes an EGR opening degree control unit that controls the opening degree of the EGR valve, and the EGR opening degree control unit is configured to execute the abnormality detection process by the abnormality detection unit. It is desirable to increase the opening of the EGR valve.

  When the EGR valve is open, the exhaust discharged from the combustion chamber of the engine body to the exhaust passage flows into the intake passage through the EGR passage. Since the phase of exhaust pulsation flowing into the intake passage is close to the phase of intake pulsation in the intake passage, when exhaust flows into the intake passage, the pulsation of intake air in the intake passage is amplified.

  In the above configuration, the EGR opening is increased when the abnormality detection process is executed. Thereby, the intake pulsation when the PCV piping is normal is amplified, and the difference in pulsation can be further increased with respect to the pulsation when the PCV piping is abnormal. Therefore, according to the above configuration, the PCV piping abnormality detection accuracy can be further improved.

  In the abnormality detection apparatus for an internal combustion engine, it is preferable that the abnormality detection unit performs the abnormality detection process based on the magnitude of the pulsation when the operation state of the internal combustion engine is during idle operation.

  In the above configuration, the abnormality detection process is executed based on the intake air pulsation during the idling operation in which the intake air pulsation is stable. Therefore, in the abnormality detection process based on the pulsation of intake air, it can contribute to the improvement of the detection accuracy.

1 is a cross-sectional view schematically showing the configuration of an embodiment of an abnormality detection device for an internal combustion engine. The flowchart which shows the flow of a series of processes which concern on the abnormality detection control which the abnormality detection apparatus of an internal combustion engine performs. (A)-(e) is a time chart which shows typically transition of a crank angle and the pulsation of the intake air which arises in an intake passage. The timing chart which shows typically the calculation aspect of the locus | trajectory length in the pulsation of intake. (A)-(i) is a timing chart which shows the abnormality determination aspect in abnormality detection control. The flowchart which shows the flow of a series of processes which concern on the abnormality detection control which the abnormality detection apparatus of the internal combustion engine of another example performs.

  An embodiment of an abnormality detection device for an internal combustion engine will be described with reference to FIGS. In the present embodiment, an abnormality detection device applied to an in-line four-cylinder diesel internal combustion engine will be described as an example.

  As shown in FIG. 1, an engine body 10 of an internal combustion engine mounted on a vehicle includes a cylinder block 11. The cylinder block 11 is formed with a cylinder 11A. Four cylinders 11A are arranged side by side in a predetermined direction (depth direction in FIG. 1). Each cylinder 11A accommodates a piston 12 in a reciprocating manner. One end of a connecting rod 13 is connected to the piston 12. The other end of the connecting rod 13 is connected to a crankshaft 14 that is an output shaft of the internal combustion engine. The crankshaft 14 has an arm portion 14A to which the connecting rod 13 is connected, and a shaft portion 14B to which the arm portion 14A is fixed. A disc-shaped timing rotor 15 that rotates integrally with the shaft portion 14 </ b> B is connected to one end of the crankshaft 14. On the outer peripheral surface of the timing rotor 15, a plurality of teeth (not shown) are provided side by side in the circumferential direction. A crank angle sensor 90 is provided in the internal combustion engine so as to face the outer peripheral surface of the timing rotor 15. The crank angle sensor 90 outputs an electrical signal according to the passage of teeth provided on the outer peripheral surface of the timing rotor 15.

  A crankcase 16 is attached to the lower end of the cylinder block 11. An oil pan 17 in which oil is stored is attached to the lower end of the crankcase 16. The cylinder block 11, the crankcase 16, and the oil pan 17 constitute a crank chamber 18 that houses the crankshaft 14.

  The internal combustion engine is provided with an oil supply system 19 that supplies oil stored in the oil pan 17 to each part of the internal combustion engine. The oil supply system 19 has an oil supply passage 19A, one end of which is disposed in the oil pan 17, and an oil pump 19B provided on the oil supply passage 19A. The oil pump 19B is, for example, an engine-driven pump, and pumps oil stored in the oil pan 17 into the oil supply passage 19A as the crankshaft 14 rotates. The other end of the oil supply passage 19 </ b> A is branched into a plurality of parts, each extending to each part of the engine body 10. Oil is supplied to each part of the engine body 10 through the oil supply passage 19A.

  A cylinder head 20 is connected to the upper end of the cylinder block 11. A combustion chamber 21 is configured by the cylinder 11 </ b> A, the piston 12, and the cylinder head 20. An intake port 22 and an exhaust port 23 communicating with the combustion chamber 21 are formed in the cylinder head 20. An intake valve 24 is disposed in the intake port 22. An exhaust valve 25 is disposed in the exhaust port 23.

  A cylinder head cover 26 is attached to the upper end portion of the cylinder head 20. A storage chamber 27 is configured by the cylinder head 20 and the cylinder head cover 26. A valve operating mechanism 28 that opens and closes the intake valve 24 and the exhaust valve 25 is stored in the storage chamber 27. Oil is supplied to the valve operating mechanism 28 through an oil supply system 19. The storage chamber 27 communicates with the crank chamber 18 through an oil return passage 29. The oil return passage 29 extends through the cylinder head 20 and the cylinder block 11. The oil that has lubricated the valve mechanism 28 is discharged to the crank chamber 18 through the oil return passage 29.

The engine body 10 of the internal combustion engine includes a cylinder block 11, a crankcase 16, an oil pan 17, a cylinder head 20, and a cylinder head cover 26.
An intake pipe 30 constituting an intake passage is connected to the engine body 10 of the internal combustion engine. Intake air is introduced into the combustion chamber 21 through the intake passage. The intake pipe 30 is provided with a throttle valve 31. The throttle valve 31 controls the amount of intake air flowing from the intake passage to the combustion chamber 21, and generates a negative pressure on the intake downstream side of the throttle valve 31. Note that, as the opening degree of the throttle valve 31 is smaller, the negative pressure generated on the downstream side of the intake air than the throttle valve 31 becomes larger. A throttle motor 32 that opens and closes a throttle valve 31 is connected to the intake pipe 30. A throttle sensor 91 that detects the opening of the throttle valve 31 is connected to the throttle motor 32. The intake pipe 30 is provided with an air flow meter 92 that detects the flow rate of the intake air flowing through the intake pipe 30 on the intake upstream side of the throttle valve 31 in the intake flow direction. When the valve mechanism 28 opens the intake valve 24 while the piston 12 of the engine body 10 is lowered, intake air flows into the combustion chamber 21 through the intake passage. Further, when the valve mechanism 28 closes the intake valve 24, the inflow of intake air to the combustion chamber 21 through the intake passage is stopped. By repeatedly flowing in and stopping the intake air into the combustion chamber 21 in each cylinder 11A, intake air pulsation occurs in the intake passage. Thus, the intake pulsation in the intake passage caused by opening and closing the intake valve 24 is transmitted from the intake downstream side to the intake upstream side.

  In the internal combustion engine, gas may leak from the combustion chamber 21 to the crank chamber 18 through between the piston 12 and the cylinder 11A. The gas leaking from the combustion chamber 21 to the crank chamber 18 in this way is called blow-by gas. The internal combustion engine is provided with a PCV pipe 40 for discharging blow-by gas from the crank chamber 18 to flow into the intake passage. One end of the PCV pipe 40 is connected to the cylinder head cover 26 of the engine body 10. The PCV pipe 40 communicates with the crank chamber 18 through the storage chamber 27 and the oil dropping passage 29. The other end of the PCV pipe 40 is connected between the throttle valve 31 and the air flow meter 92 in the intake pipe 30. That is, the other end of the PCV pipe 40 is connected to the intake upstream side of the throttle valve 31 in the intake passage and to the intake downstream side of the air flow meter 92.

  The intake pulsation transmitted from the intake pipe 30 to the intake upstream side of the throttle valve 31 is also transmitted to the PCV pipe 40. By transmitting the pulsation in this way, blow-by gas flows from the crank chamber 18 to the intake pipe 30 through the PCV pipe 40. That is, the pressure of the PCV pipe 40 fluctuates according to the intake pulsation, and the pressure of the PCV pipe 40 periodically becomes lower than the pressure of the crank chamber 18, so that the oil drop passage 29, the storage chamber 27, The blow-by gas flows into the intake pipe 30 through the PCV pipe 40.

  An exhaust pipe 50 constituting an exhaust passage is connected to the engine body 10 of the internal combustion engine. The exhaust pipe 50 communicates with the exhaust port 23. When the valve mechanism 28 opens the exhaust valve 25 while the piston 12 of the engine body 10 is rising, the exhaust is discharged from the combustion chamber 21 to the exhaust passage. Further, when the valve operating mechanism 28 closes the exhaust valve 25, the exhaust of the exhaust gas from the combustion chamber 21 to the exhaust passage is stopped. By repeatedly discharging and stopping exhaust from the combustion chamber 21 to the exhaust passage in each cylinder 11A, exhaust pulsation occurs in the exhaust passage. The exhaust pulsation has the same frequency as the intake pulsation, and the phase is substantially the same.

  The internal combustion engine is provided with an EGR device 60 for causing the exhaust to flow from the exhaust passage to the intake passage. The EGR device 60 has an EGR passage 61 having one end connected to the exhaust pipe 50 and the other end connected to the intake downstream side of the throttle valve 31 in the intake pipe 30. The EGR passage 61 communicates the exhaust passage and the intake downstream of the throttle valve 31 in the intake passage. An EGR cooler 62 is provided on the path of the EGR passage 61. The EGR cooler 62 cools the exhaust gas flowing through the EGR passage 61. Further, an EGR valve 63 is disposed in the EGR passage 61 closer to the intake pipe 30 than the EGR cooler 62. The EGR valve 63 is an electric valve, and the opening degree changes according to the energization amount to change the flow path cross-sectional area of the EGR passage 61. Since the pressure of the exhaust gas discharged into the exhaust pipe 50 is higher than the pressure of the intake air in the intake pipe 30, the exhaust gas flows into the intake pipe 30 through the EGR passage 61 when the EGR valve 63 is opened. Note that the amount of exhaust flowing through the EGR passage 61 to the intake passage can be adjusted by controlling the opening degree of the throttle valve 31 to adjust the negative pressure on the intake pipe 30 at the downstream side of the throttle valve 31.

  Output signals from the crank angle sensor 90, the throttle sensor 91, and the air flow meter 92 are input to the control device 70 for the internal combustion engine. The control device 70 also receives output signals from an accelerator sensor 93 that detects the amount of depression of the accelerator pedal, a vehicle speed sensor 94 that detects the vehicle speed, and the like. The control device 70 includes, as function units, a throttle opening calculation unit 71, a throttle opening control unit 72, a rotation speed calculation unit 73, an operating state detection unit 74, a pulsation detection unit 75, a trajectory length calculation unit 77, and an abnormality detection unit 78. And an EGR opening degree control unit 82. The control device 70 executes abnormality detection control for detecting abnormality whether the PCV pipe 40 is detached from the cylinder head cover 26 or the intake pipe 30.

The throttle opening calculation unit 71 calculates the opening of the throttle valve 31 based on the output signal from the throttle sensor 91.
The throttle opening control unit 72 controls the opening of the throttle valve 31 by operating the throttle motor 32 based on output signals from the crank angle sensor 90, the accelerator sensor 93, and the like. When the abnormality detection control is started, the throttle valve 31 is controlled to be fully opened when the opening of the throttle valve 31 calculated by the throttle opening calculator 71 is less than a predetermined opening.

  The rotational speed calculation unit 73 calculates the rotational speed of the crankshaft 14 of the internal combustion engine based on the output signal from the crank angle sensor 90. The operation state detection unit 74 detects the operation state of the internal combustion engine based on the rotation speed calculated by the rotation speed calculation unit 73 and the output signal from the accelerator sensor 93. This operation state includes a plurality of operation states such as an idle operation state.

  The pulsation detector 75 detects the pulsation of the intake air flowing through the intake passage based on the output signal from the air flow meter 92. The air flow meter 92 functions as a pulsation detection sensor. Further, the pulsation detecting unit 75 has a band pass filter 76 that passes an output signal in a frequency range corresponding to the intake pulsation in the intake passage among the output signals from the air flow meter 92. The band pass filter 76 changes the frequency range of the output signal to be passed among the output signals from the air flow meter 92 according to the rotation speed calculated by the rotation speed calculation unit 73.

  The trajectory length calculation unit 77 has a trajectory per one cycle of the intake pulsation, which is a correlation value correlated with the magnitude of the pulsation from the pulsation of the intake air detected by the pulsation detection unit 75 as a cycle of 720 ° CA. The length ΣTL is calculated. The pulsation detecting unit 75 and the trajectory length calculating unit 77 correspond to a correlation value calculating unit.

  In the abnormality detection control, the abnormality detection unit 78 performs an abnormality detection process on the condition that the opening of the throttle valve 31 calculated by the throttle opening calculation unit 71 is equal to or greater than a predetermined opening. In the abnormality detection process, the displacement of at least one of the cylinder head cover 26 and the intake pipe 30 of the PCV pipe 40 is detected based on the fact that the pulsation trajectory length ΣTL calculated by the trajectory length calculation unit 77 is equal to or less than the determination value. The abnormality detection unit 78 includes an opening degree determination unit 79, a determination value storage unit 80, and a temporary determination execution unit 81. The opening degree determination unit 79 determines whether the opening degree of the throttle valve 31 is equal to or greater than a predetermined opening degree as an execution condition for the abnormality detection process. The determination value storage unit 80 stores and holds in advance a determination value for performing the abnormality detection process. The provisional determination execution unit 81 compares the intake pulsation locus length ΣTL calculated by the locus length calculation unit 77 with the determination value stored in the determination value storage unit 80 to make a provisional determination of occurrence of abnormality. .

  When the abnormality detection control is started, the EGR opening degree control unit 82 executes energization control to the EGR valve 63 and controls the EGR valve 63 to a fully opened state. The abnormality detection device for the internal combustion engine is configured by a control device 70.

  Next, a flow of a series of processes related to the abnormality detection control executed by the control device 70 for the internal combustion engine will be described with reference to the flowchart of FIG. A series of processes related to the abnormality detection control is repeatedly executed at predetermined intervals (for example, 720 ° CA).

  As shown in FIG. 2, when this series of processing is executed, the control device 70 first determines whether or not the operating state of the internal combustion engine is idling (step S200). In this process, an affirmative determination is made when the operation state of the internal combustion engine calculated by the operation state detection unit 74 is an idle operation state. If it is determined in step S200 that the internal combustion engine is idling (step S200: YES), abnormality detection control is started, and the throttle opening control unit 72 then opens the opening θt of the throttle valve 31. Is calculated (step S201).

  When the opening degree θt of the throttle valve 31 is thus calculated, the control device 70 determines whether or not the opening degree θt of the throttle valve 31 is less than the predetermined opening degree θa (step S202). When the opening degree θt of the throttle valve 31 is small, the transmission of the intake pulsation from the intake downstream side to the intake upstream side is suppressed, so the intake pulsation detected by the air flow meter 92 becomes small. Further, even when there is an abnormality when the PCV pipe 40 is disconnected, the intake pulsation detected by the air flow meter 92 is reduced. When one end of the PCV pipe 40 is detached from the engine body 10, one end of the PCV pipe 40 becomes an open end. When the other end of the PCV pipe 40 is detached from the intake pipe 30, the connection port between the PCV pipe 40 and the intake pipe 30 is opened. As described above, when the PCV pipe 40 is disconnected, it is easy for the outside air to flow into the intake pipe 30 from the open end or the connection port, and the pulsation of the intake air transmitted through the intake passage is attenuated by the inflow of the outside air. The intake pulsation transmitted to the intake upstream side of the PCV pipe 40 becomes smaller.

  Therefore, the magnitude of the intake pulsation detected by the air flow meter 92 tends to be small both when the opening θt of the throttle valve 31 is small and when the abnormality of the PCV piping 40 occurs. Becomes smaller. In the present embodiment, the predetermined opening degree θa is set as follows. That is, the magnitude of the intake pulsation in the intake passage is normal when the PCV pipe 40 is not detached from the cylinder head cover 26 and the intake pipe 30 and when the PCV pipe 40 is abnormal from the cylinder head cover 26 and the intake pipe 30. Among the opening degrees of the throttle valve 31 that cause a sufficient difference, the minimum opening degree is set to the predetermined opening degree θa. The predetermined opening θa is obtained in advance through experiments or the like and stored in the control device 70, and is set to an opening smaller than the opening corresponding to the fully opened state of the throttle valve 31.

  When it is determined in step S202 that the opening degree θt of the throttle valve 31 is less than the predetermined opening degree θa (step S202: YES), the process proceeds to step S203. In the process of step S203, the throttle opening degree control unit 72 controls the throttle valve 31 to a fully open state. Thereby, the opening degree θt of the throttle valve 31 becomes equal to or larger than the predetermined opening degree θa. Thereafter, the EGR opening degree control unit 82 executes energization control to the EGR valve 63 and controls the EGR valve 63 to a fully open state (step S204).

  If it is determined in step S202 that the opening θt of the throttle valve 31 is equal to or greater than the predetermined opening θa (step S202: NO), the process proceeds to step S204 without performing step S203. Then, the EGR valve 63 is fully opened.

  Thereafter, the pulsation detecting unit 75 detects the pulsation of the intake air on the intake upstream side of the throttle valve 31 in the intake passage (step S205). In this process, the output signal of the air flow meter 92 is input to the pulsation detector 75.

  As shown in the time chart of FIG. 3, the control device 70 of the internal combustion engine detects the crank angle of the internal combustion engine based on the output signal from the crank angle sensor 90 (FIG. 3A). The intake pulsation in the intake passage caused by opening and closing of the intake valve 24 accompanying the operation of the internal combustion engine is transmitted from the intake downstream side to the intake upstream side and reflected in the output signal of the air flow meter 92 (FIG. 3B). . The air flow meter 92 outputs, for example, a voltage signal as an output signal corresponding to the flow rate of the intake air at every predetermined time (for example, 4 ms). In the pulsation detecting unit 75, when the output signal from the air flow meter 92 is captured, the band pass filter 76 extracts an output signal in a frequency range corresponding to the intake pulsation in the intake passage from the output signal from the air flow meter 92. The frequency of intake pulsation in the intake passage is affected by the rotational speed of the internal combustion engine. That is, the higher the rotational speed of the internal combustion engine, the higher the intake pulsation frequency. Therefore, the band pass filter 76 changes the frequency range of the output signal to be passed among the output signals from the air flow meter 92 according to the rotation speed calculated by the rotation speed calculation unit 73. In this way, the pulsation detecting unit 75 detects the pulsation of the intake air in the intake passage (FIG. 3C). Note that the pulsation detecting unit 75 amplifies the signal extracted by the bandpass filter 76 to increase its dynamic range. As shown by the solid line in FIG. 3C, the intake pulsation when the opening degree θt of the throttle valve 31 is equal to or larger than the predetermined opening degree θa is the opening of the throttle valve 31 as shown by the broken line in FIG. The degree θt is larger than the intake pulsation when it is less than the predetermined opening degree θa.

  As shown in FIG. 3D, when the PCV pipe 40 is disconnected, the intake air pulsation in the intake passage is difficult to be transmitted to the air flow meter 92, and the fluctuation in the output signal of the air flow meter 92 is small. Become. Therefore, as shown in FIG. 3E, the intake pulsation detected by the pulsation detector 75 is smaller than when the PCV piping 40 is normal (solid line and broken line in FIG. 3C).

  In the present embodiment, the intake valves 24 are driven to open and close in all of the four cylinders 11A at 720 ° CA, so that the intake air flows into the combustion chamber 21 four times. For this reason, as shown in FIGS. 3C and 3E, the intake pulsation in the intake passage has four peaks and valleys around 720 ° CA.

  When the intake pulsation is detected in this way, the process proceeds to step S206 in FIG. 2, and the locus length calculation unit 77 calculates the locus length ΣTL of the pulsation per 720 ° CA from the pulsation of the intake air detected by the pulsation detection unit 75. To do.

As shown in FIG. 4, the trajectory length calculation unit 77 determines the difference between the previous value TL _(n−1) and the current value TL _(n) of the value corresponding to the signal obtained from the air flow meter 92 in the pulsation of intake air. The absolute value ΔTL _(n) (> 0) is calculated, and this is integrated for 720 ° CA to calculate the trajectory length ΣTL (= ΔTL ₍₁₎ + TL ₍₂₎ +... + ΔTL ₍₃₂₎ ). As described above, the air flow meter 92 outputs an output signal corresponding to the flow rate of the intake air every predetermined time. Therefore, the trajectory length calculation unit 77 calculates the trajectory length ΣTL by integrating the absolute value ΔTL calculated every predetermined time until the crank angle is changed from 0 ° CA to 720 ° CA. The trajectory length ΣTL correlates with the magnitude of intake air pulsation in the intake passage, and the trajectory length ΣTL increases as the pulsation increases.

  When the trajectory length ΣTL is calculated in this way, the abnormality detection unit 78 performs the processing after step S207 in FIG. First, the abnormality detection unit 78 determines whether the opening degree θt of the throttle valve 31 is equal to or larger than a predetermined opening θa by the opening degree determination unit 79 and determines whether or not an execution condition for the abnormality detection process is satisfied. In this embodiment, when a negative determination is made in the process of step S202 when the abnormality detection process is executed, that is, when the opening degree θt of the throttle valve 31 is less than the predetermined opening degree θa, the process of step S203 is executed. Thus, the opening degree θt of the throttle valve 31 becomes equal to or larger than the predetermined opening degree θa. Therefore, since the opening degree θt of the throttle valve 31 is equal to or larger than the predetermined opening degree θa and the execution condition is satisfied before the process of step S207, step S207 is performed after the process of step S206 is executed. In this process, the abnormality detection process is started.

  When starting the abnormality detection process, the abnormality detection unit 78 increments the execution counter (step S208). Thereby, the number of times of performing the abnormality detection process is counted. Thereafter, the process proceeds to step S <b> 209, and the provisional determination execution unit 81 determines whether or not the intake pulsation trajectory length ΣTL is equal to or less than the determination value stored in the determination value storage unit 80. In this embodiment, the determination value is set to be the same value as the intake pulsation trajectory length ΣTL when the opening degree θt of the throttle valve 31 is the predetermined opening degree θa. That is, the determination value is set within the range of the locus length ΣTL when the PCV pipe 40 is connected to the engine body 10 and the intake passage and is normal, and the opening θt of the throttle valve 31 is equal to or larger than the predetermined opening θa. Is set to a value that is smaller than the trajectory length ΣTL of the intake pulsation at a time that is greater than the trajectory length ΣTL of the intake pulsation when an abnormality occurs in the PCV pipe 40. The determination value is obtained in advance by experiments or the like and stored in the determination value storage unit 80.

  When it is determined in step S209 that the intake air pulsation trajectory length ΣTL is equal to or smaller than the determination value (step S209: YES), the process proceeds to step S210, and the abnormality detection unit 78 increments the abnormality counter. To do. The abnormality counter is a counter that indicates the number of times that the PCV pipe 40 is provisionally determined to be detached from at least one of the cylinder head cover 26 and the intake pipe 30. Thereafter, the process proceeds to step S211.

  If it is determined in step S209 that the intake air pulsation trajectory length ΣTL exceeds the determination value (step S209: NO), the process proceeds to step S211 without incrementing the abnormality counter.

  In the process of step S211, it is determined whether or not the execution counter is greater than or equal to a threshold value. For example, 100 is set as the threshold. When the execution counter reaches the threshold value (step S211: YES), the abnormality detection unit 78 next detects an abnormality in the PCV piping 40 (step S212). In this process, the ratio R (= abnormal counter / execution counter × 100) of the number of times that the PCV piping 40 is provisionally determined to be abnormal is greater than or equal to the abnormal ratio (for example, 90%) with respect to the number of executions of the abnormality detection process The abnormality of the PCV piping 40 is detected depending on whether or not. That is, if the ratio R is equal to or higher than the abnormal ratio, it is determined that an abnormality has occurred in the PCV piping 40 and an abnormality is detected. Thereafter, the process proceeds to step S213, the execution counter and the abnormality counter are reset, and the series of processes relating to the abnormality detection control is terminated.

  If the execution counter does not reach the threshold value in the process of step S211 (step S211: NO), the series of processes related to the abnormality detection control is terminated without executing the subsequent processes. Thus, the abnormality counter is held until the execution counter reaches the threshold value, and the number of times that the abnormality is detected temporarily in the PCV piping 40 is counted each time the abnormality detection processing by the abnormality detection unit 78 is executed. The processing from step S207 to step S213 corresponds to abnormality detection processing.

  When it is determined that the internal combustion engine is not idling (step S200: NO), the control device 70 ends the series of processes related to the abnormality detection control without performing the subsequent processes. When the series of processes relating to the abnormality detection control is thus completed, the throttle opening degree control unit 72 increases the opening degree of the throttle valve 31 before increasing the opening degree of the throttle valve 31 in the process of step S203. Return to the opening. Moreover, the EGR opening degree control part 82 returns the opening degree of the EGR valve 63 to the original opening degree before increasing the opening degree of the EGR valve 63 in the process of step S204.

  Next, an abnormality determination mode by abnormality detection control will be described with reference to the timing chart of FIG. In the present embodiment, an example will be described in which it is determined that the opening degree θt of the throttle valve 31 is less than the predetermined opening degree θa in the process of step S202 in the series of processes related to the abnormality detection control.

  As shown in FIG. 5A, the control device 70 for the internal combustion engine calculates a crank angle as the internal combustion engine is operated. Further, the control device 70 for the internal combustion engine starts the abnormality detection control assuming that the execution condition of the abnormality detection control is satisfied at the timing t1 when the internal combustion engine is in the idling operation. In this example, as shown in FIG. 5B, the timing t1 coincides with the time when the crank angle is 0 °. Thereafter, a series of processing relating to abnormality detection control is repeatedly executed at predetermined intervals.

  As shown by the solid line in FIGS. 5C and 5D, when the abnormality detection control is executed, the opening degree θt of the throttle valve 31 is less than the predetermined opening degree θa, so that the throttle valve 31 is fully opened. Thus, the EGR valve 63 is also controlled to be fully opened. As shown by the solid line in FIG. 5 (e), the air flow meter 92 detects the flow rate of the intake air upstream of the throttle valve 31 in the intake passage, and outputs the output signal to the control device 70 of the internal combustion engine at predetermined time intervals. Is entered.

  When the PCV piping 40 is normal, the abnormality detection control is started at the timing t1, and the opening degree of the throttle valve 31 is fully opened, so that the intake pulsation in the intake passage increases as compared to before. Further, since the EGR valve 63 is fully opened, the amount of exhaust gas flowing from the exhaust passage into the intake passage through the EGR passage 61 is maximized. The phase of the exhaust pulsation flowing into the intake passage is substantially the same as the phase of the intake pulsation in the intake passage. Therefore, when the amount of exhaust flowing into the intake passage increases, the intake pulsation in the intake passage is amplified. Therefore, when the opening degree of the EGR valve 63 is fully opened, the increase width of the intake pulsation in the intake passage is further increased. Therefore, the fluctuation of the output signal of the air flow meter 92 increases after the timing t1.

  On the other hand, as shown by the broken line in FIG. 5E, when the PCV piping 40 is abnormal, the intake pulsation in the intake passage is difficult to be transmitted to the air flow meter 92, and fluctuations in the output signal of the air flow meter 92 are not. Get smaller. Thus, even when an abnormality has occurred in the PCV piping 40, the output signal of the air flow meter 92 slightly fluctuates.

  Such an output signal from the air flow meter 92 is input to the pulsation detector 75, and the intake pulsation in the intake passage is detected as shown in FIG. 5 (f). That is, the pulsation detection unit 75 detects intake pulsation when the throttle valve 31 has an opening θt that is equal to or larger than the predetermined opening θa and is in an idling operation. The output signal of the air flow meter 92 reflects not only the influence due to the pulsation of the intake air but also the influence of noise and disturbance of the air flow meter 92. Therefore, the pulsation detecting unit 75 processes the output signal of the air flow meter 92 by the band pass filter 76 and extracts the output signal corresponding to the frequency of the intake pulsation in the intake passage from the output signal from the air flow meter 92. The band pass filter 76 changes the frequency range of the signal to be passed among the output signals from the air flow meter 92 according to the operating state of the internal combustion engine.

  If the PCV piping 40 is normal, the detected intake pulsation increases as shown by the solid line in FIG. 5 (f), and if an abnormality occurs in the PCV piping 40, the broken line in FIG. 5 (f). As shown, the detected intake pulsation is reduced. Further, when the PCV piping 40 is normal, the intake air pulsation when the opening degree θt of the throttle valve 31 is equal to or larger than the predetermined opening degree θa is shown in FIG. As shown by the one-dot chain line, the opening degree θt of the throttle valve 31 is larger than the intake air pulsation when the opening degree θt is less than the predetermined opening degree θa. The magnitude of the intake pulsation when the opening θt of the throttle valve 31 is less than the predetermined opening θa is slightly larger than the magnitude of the intake pulsation when an abnormality occurs in the PCV pipe 40. Thereafter, as shown in FIG. 5G, the trajectory length ΣTL is integrated and calculated.

  When the trajectory length ΣTL is calculated, the abnormality detection unit 78 executes an abnormality detection process for the PCV pipe 40. In the abnormality detection process, first, as shown in FIG. 5 (i), the execution counter is incremented, and a temporary determination of abnormality detection is performed. That is, as indicated by a solid line in FIG. 5G, the intake pulsation trajectory length ΣTL when the PCV piping 40 is normal increases before reaching 720 ° CA and exceeds the determination value. On the other hand, as shown by a broken line in FIG. 5G, the trajectory length ΣTL of the intake pulsation when an abnormality occurs in the PCV piping 40 is not so large even at 720 ° CA, and is not more than the determination value. Become. Therefore, as shown by a solid line in FIG. 5 (h), if the PCV piping 40 is normal, the abnormality counter is not incremented, and an abnormality has occurred in the PCV piping 40 as shown by a broken line in FIG. 5 (h). If so, the abnormality counter is incremented. Thereafter, the execution counter is incremented by repeatedly executing the abnormality detection control at predetermined intervals. And abnormality determination is performed in abnormality detection control when an execution counter reaches 100 which is a threshold value. Thereby, the abnormality of the PCV piping 40 is detected. As indicated by the alternate long and short dash line in FIG. 5G, when the opening degree θt of the throttle valve 31 is less than the predetermined opening degree θa, the trajectory length ΣTL of the intake pulsation does not exceed the determination value. When an abnormality is detected, the abnormality detection unit 78 stores that fact, and enables an operator to detect that an abnormality has occurred by accessing the abnormality detection unit 78 during maintenance or the like. Thereafter, as shown in FIGS. 5H and 5I, the abnormality counter and the execution counter are reset at timing t2. Thus, in the present embodiment, based on the output signal from the air flow meter 92, the correlation value correlates with the magnitude of the intake pulsation when the opening degree θt of the throttle valve 31 is equal to or larger than the predetermined opening degree θa. A certain trajectory length ΣTL is calculated, and an abnormality in the PCV pipe 40 is detected based on the calculated trajectory length ΣTL in the abnormality detection process. In other words, the abnormality detection unit 78 performs an abnormality detection process based on the magnitude of intake pulsation when the opening degree θt of the throttle valve 31 is equal to or larger than the predetermined opening degree θa.

The effect of this embodiment is demonstrated.
(1) Based on the magnitude of the intake pulsation in the state where the opening degree θt of the throttle valve 31 is equal to or larger than the predetermined opening degree θa, the detection process of the PCV pipe 40 coming off from the engine body 10 or the intake passage, that is, the PCV pipe 40 Anomaly detection processing was performed. Therefore, the intake pulsation in the intake passage is easily transmitted from the intake downstream side of the throttle valve 31 to the intake upstream side, and when the PCV piping 40 is not separated from the engine body 10 and the intake passage, and when the PCV piping 40 is connected to the engine body 10 and The abnormality of the PCV pipe 40 can be detected based on the intake pulsation under a situation in which a sufficient difference is likely to occur in the magnitude of the intake pulsation in the intake passage at the time of abnormality that is out of the intake passage. That is, when the PCV piping 40 is normal, the trajectory length ΣTL (solid line in FIG. 5G) when the opening θt of the throttle valve 31 is equal to or larger than the predetermined opening θa is abnormal in the PCV piping 40. Is longer than the locus length ΣTL (broken line in FIG. 5G). Further, when the PCV piping 40 is normal, the trajectory length ΣTL (the one-dot chain line in FIG. 5G) when the opening θt of the throttle valve 31 is less than the predetermined opening θa is that the PCV piping 40 is abnormal. It is slightly longer than the trajectory length ΣTL at a certain time (broken line in FIG. 5G). Therefore, the difference between the trajectory length ΣTL when the throttle valve 31 opening θt is equal to or larger than the predetermined opening θa and the trajectory length ΣTL when the PCV piping 40 is abnormal is that the opening θt of the throttle valve 31 is predetermined open. It becomes larger than the difference between the trajectory length ΣTL when the degree is less than θa and the trajectory length ΣTL when the PCV pipe 40 is abnormal. For this reason, it is possible to suppress erroneous detection as abnormal even though no abnormality has occurred in the PCV piping 40, and erroneous detection as normal although abnormality has occurred in the PCV piping 40. Therefore, it is possible to improve the detection accuracy of the abnormality of the PCV pipe 40 by suppressing erroneous detection of normality and abnormality of the PCV pipe 40.

  (2) When performing the abnormality detection process by the abnormality detection unit 78, when the opening degree θt of the throttle valve 31 is less than the predetermined opening degree θa, the opening degree θt of the throttle valve 31 is set to a fully opened state that is equal to or larger than the predetermined opening degree θa. I have control. Therefore, when the abnormality detection process is executed, the opening degree θt of the throttle valve 31 is in a state equal to or larger than the predetermined opening degree θa, and the detection of intake pulsation in this state can be ensured. Therefore, the detection frequency of abnormality detection can be increased. In addition, since the abnormality detection process has an execution condition that the opening degree θt of the throttle valve 31 is equal to or larger than the predetermined opening degree θa, the execution condition can be adjusted in advance when the abnormality detection process is executed. Can be executed more frequently.

  (3) When the EGR valve 63 is open, the exhaust discharged from the combustion chamber 21 of the engine body 10 into the exhaust passage flows into the intake passage through the EGR passage 61. Since the phase of exhaust pulsation flowing into the intake passage is close to the phase of intake pulsation in the intake passage, when exhaust flows into the intake passage, the pulsation of intake air in the intake passage is amplified.

  In the present embodiment, when the abnormality detection process is executed, the opening degree of the EGR valve 63 is increased so as to be fully opened. Thereby, the intake pulsation when the PCV piping 40 is normal is amplified, and the difference in pulsation can be further increased with respect to the pulsation when the PCV piping 40 is abnormal. Therefore, the abnormality detection accuracy of the PCV pipe 40 can be further improved.

  (4) In this embodiment, the abnormality detection process is performed based on the intake pulsation when the operating state of the internal combustion engine is idling. Therefore, the abnormality detection process can be executed based on the intake pulsation in a stable state, and the abnormality detection process based on the intake pulsation can contribute to improvement in detection accuracy.

  Further, when the operation state of the internal combustion engine is an idle operation state, the fuel injection amount is small. Therefore, even if the opening degree θt of the throttle valve 31 is increased during the abnormality detection process, the combustion temperature is hardly increased so that an increase in the amount of NOx contained in the exhaust can be suppressed. Therefore, by performing the abnormality detection process when the operating state of the internal combustion engine is idling, it is possible to suppress the influence on the deterioration of the exhaust property due to the change in the opening θt of the throttle valve 31.

  (5) During the idling operation where the rotational speed of the internal combustion engine is low, the time required for rotating the crank angle by 720 ° CA becomes longer. Therefore, the number of signals input from the air flow meter 92 to the control device 70 per 720 ° CA is larger than in an operation state in which the engine speed is higher than in an idle operation state. Therefore, by executing the abnormality detection control during the idle operation, the detection accuracy of pulsation is increased, and it is possible to contribute to increasing the abnormality detection accuracy of the PCV pipe 40.

  (6) In this embodiment, the determination value of the trajectory length ΣTL is set to be the same value as the trajectory length ΣTL of the intake pulsation when the opening θt of the throttle valve 31 is the predetermined opening θa. In order to determine when the PCV piping 40 is normal or abnormal by comparing the trajectory length ΣTL and the determination value, the determination value is the intake pulsation when the PCV piping 40 is normal. It is necessary to set the length to be shorter than the trajectory length ΣTL and larger than the trajectory length ΣTL of the intake pulsation when an abnormality occurs in the PCV pipe 40.

  Here, when the determination value is set so as to include when the opening degree θt of the throttle valve 31 is less than the predetermined opening degree θa (the one-dot chain line in FIG. 5G) in the normal state, the determination value is set in FIG. It is necessary to set a value smaller than the determination value shown in g). That is, when the opening degree θt of the throttle valve 31 is less than the predetermined opening degree θa, the magnitude of the intake pulsation is smaller than when the opening degree θt of the throttle valve 31 is equal to or larger than the predetermined opening degree θa. Therefore, the value of the trajectory length ΣTL calculated at 720 ° CA is small. Therefore, by setting the determination value to a small value, the determination value is set so that the locus length ΣTL exceeds the determination value even when the opening θt of the throttle valve 31 is less than the predetermined opening θa. Need to be set. Even in such a case, the determination value needs to be set to be longer than the intake pulsation trajectory length ΣTL when an abnormality occurs in the PCV piping 40. In such a case, the determination value is smaller than the determination value shown in FIG. 5G, and the position is set below the position of the determination value shown in FIG. As a result, as compared with the case where the determination value is set as shown in FIG. 5G, the difference between the locus length ΣTL (broken line in FIG. 5G) at the time of abnormality and the determination value becomes smaller. In this case, when noise is superimposed on the intake pulsation or the value of the trajectory length ΣTL slightly fluctuates, it is erroneously detected that there is no abnormality in the PCV piping 40, or there is an abnormality in the PCV piping 40. In spite of the occurrence, there is a risk of false detection as normal. In this embodiment, the determination value is set to the same value as the trajectory length ΣTL of the intake pulsation when the opening θt of the throttle valve 31 is the predetermined opening θa. Therefore, the determination value becomes a large value as shown in FIG. 5G, and is set when the opening angle θt of the throttle valve 31 is set within the range of the intake air pulsation trajectory length ΣTL when it is less than the predetermined opening θa. In comparison, the difference between the determination value and the locus length ΣTL at the time of abnormality becomes large. Therefore, by comparing the trajectory length ΣTL and the determination value, when detecting an abnormality in the PCV piping 40, it is possible to suppress the detection of normality or abnormality in the PCV piping 40, and further improve the detection accuracy. Can contribute.

  (7) In the present embodiment, the pulsation detector 75 is provided with a bandpass filter 76. Therefore, the pulsation detecting unit 75 can extract an output signal in a frequency range corresponding to the frequency of the intake pulsation in the intake passage from the output signal from the air flow meter 92. Therefore, it is possible to remove the noise of the air flow meter 92 and the influence of disturbance, etc., which are not related to the frequency of the intake pulsation. Therefore, when detecting the occurrence of abnormality in the PCV pipe 40 based on the intake pulsation, the detection accuracy can be improved.

  (8) The band pass filter 76 is configured to change the frequency range to be passed according to the rotation speed calculated by the rotation speed calculation unit 73. Therefore, even when the operating state of the internal combustion engine changes, the pulsation detection unit 75 can extract an output signal in a frequency range corresponding to the frequency of the intake pulsation from the output signal from the air flow meter 92. Therefore, the detection accuracy of intake pulsation can be ensured even if the operating state of the internal combustion engine changes.

  (9) In the present embodiment, the abnormality detection unit 78 determines whether the ratio R of the number of times that the PCV piping 40 is temporarily determined abnormal is greater than the abnormality ratio with respect to the number of executions of the abnormality detection process. The abnormality of the piping 40 was determined. As described above, by determining the abnormality of the PCV piping 40 based on the ratio that is temporarily determined to be abnormal, a situation has occurred in which it can be temporarily determined as abnormal for some reason despite being normal. However, the accuracy of the abnormality detection processing of the PCV piping 40 can be ensured by suppressing the influence.

The above embodiment can be implemented with the following modifications. The following modifications can be implemented in combination with each other as appropriate.
-Although the example which provided the airflow meter 92 which detects the flow volume of intake was shown as a pulsation detection sensor, the other sensor which can detect the intake pulsation in an intake passage is also employable. When the intake pulsation occurs, the pressure changes in the intake passage, and therefore, for example, a pressure sensor can be employed as the pulsation detection sensor.

  -The method of the abnormality detection process of the PCV piping 40 in the abnormality detection part 78 is not restricted to the thing based on the result of the multiple times of temporary determinations as mentioned above. For example, it is possible to determine that the PCV piping 40 is abnormal when the intake air pulsation trajectory length ΣTL in the intake passage is equal to or smaller than the determination value. That is, as in the above embodiment, the abnormality detection can be performed by considering the comparison result between the trajectory length ΣTL and the determination value for a plurality of times, but the abnormality is detected based on the single comparison result between the trajectory length ΣTL and the determination value. It is also possible to perform detection. In this case, it is possible to shorten the time until the abnormality detection process is completed as compared with the above embodiment.

  The band pass filter 76 changes the frequency range of the output signal to be passed among the output signals from the air flow meter 92 in accordance with the rotational speed of the internal combustion engine, but in addition to or instead of such a configuration, the internal combustion engine The frequency range of the output signal to be passed may be changed according to the number of operating cylinders. That is, the valve mechanism 28 of the internal combustion engine may include a pause device that pauses the opening / closing drive of some of the intake valves 24 arranged corresponding to each cylinder 11A. Then, when a predetermined execution condition is satisfied, the stop device of the valve mechanism 28 is driven, and the opening / closing drive of some of the intake valves 24 arranged corresponding to each cylinder 11A is stopped. The cylinder deactivation control is executed. In such an internal combustion engine, the frequency of the intake pulsation changes according to the number of operating cylinders. Therefore, in the abnormality detection device, the bandpass filter 76 operates the operating signal in the frequency range of the output signal to be passed among the output signals from the air flow meter 92. By changing according to the number, the detection accuracy of the intake pulsation can be improved.

  The band pass filter 76 may not have a function of changing the frequency range of the output signal to be passed among the output signals of the air flow meter 92. In this case, for example, the pulsation detector 75 is provided with a plurality of band-pass filters that pass output signals in different frequency ranges. The pulsation detecting unit 75 selects a bandpass filter that passes a signal in a frequency range including the frequency of the intake pulsation in the intake passage among the plurality of bandpass filters when the operating state of the internal combustion engine changes. The output signal from the air flow meter 92 is processed by this band pass filter to detect the intake pulsation in the intake passage. Even with this configuration, it is possible to obtain the same effect as the above (8). Needless to say, the pulsation detector 75 may have only one bandpass filter that allows a signal in a predetermined frequency range to pass therethrough.

  The band-pass filter 76 may not be provided in the pulsation detection unit 75. In this case, the intake pulsation in the intake passage is detected without processing the output signal from the air flow meter 92 by the band pass filter 76.

  Although the determination value is set to be the same value as the intake air pulsation trajectory length ΣTL when the opening θt of the throttle valve 31 is the predetermined opening θa, the determination value setting mode can be changed as appropriate. is there. For example, the determination value may be set to be the same as the intake air pulsation trajectory length ΣTL when the opening degree θt of the throttle valve 31 is less than the predetermined opening degree θa. Moreover, although the example in which the determination value is a fixed value has been described, the determination value can be variably set according to, for example, the operating state of the internal combustion engine. Even in this case, the determination value is smaller than the trajectory length ΣTL of the intake passage when the PCV piping 40 is normal, and from the trajectory length ΣTL of the intake passage when the PCV piping 40 is abnormal. May be set to be larger. The determination value is set based on a value obtained through an experiment or the like, for example.

  The control device 70 for the internal combustion engine executes the abnormality detection control when the operation state of the internal combustion engine is idling, but these conditions can be changed as appropriate. For example, the abnormality detection control may be executed when the operation state of the internal combustion engine is idling and the vehicle is stopped. That is, abnormality detection may be performed based on the magnitude of intake air pulsation when the opening degree θt of the throttle valve 31 is equal to or greater than the predetermined opening degree θa, and during idling and when the vehicle is stopped. Good. It is also possible to execute abnormality detection control regardless of the operating state of the internal combustion engine and the state of the vehicle. In this case, the process of step S200 can be omitted in the flowchart of FIG.

  -When executing the abnormality detection process by the abnormality detection unit 78, the EGR valve 63 is fully opened to increase its opening. When the opening degree of the EGR valve 63 is increased, the amount of exhaust gas returned to the intake passage increases. Depending on the operating state of the internal combustion engine, if the amount of exhaust gas returned to the intake passage is too large, misfire may occur. Therefore, when increasing the opening of the EGR valve 63, the misfire does not occur in the internal combustion engine. The upper limit value of the opening degree of the EGR valve 63 may be set. Further, it is not always necessary to increase the EGR valve 63 when executing the abnormality detection process. For example, the process of step S204 in the flowchart of FIG. 2 may be omitted so that the opening degree of the EGR valve 63 is not increased when the abnormality detection process is performed.

  The throttle opening degree control unit 72 sets the opening degree θt of the throttle valve 31 to a predetermined opening degree when the opening degree θt of the throttle valve 31 is less than the predetermined opening degree θa when executing the abnormality detection process by the abnormality detecting unit 78. Any device may be used as long as it is controlled to θa or more. That is, the throttle opening degree control unit 72 only needs to increase the opening degree of the throttle valve 31 so that the opening degree is equal to or larger than the predetermined opening degree θa and equal to or smaller than the opening degree corresponding to the fully opened state. Thus, it is not always necessary to control the throttle valve 31 to the fully open state. Further, depending on the operation state of the internal combustion engine, if the opening degree of the throttle valve 31 is excessively increased, the amount of NOx discharged during combustion may exceed the allowable amount. In this case, when the opening degree of the throttle valve 31 is increased, an upper limit value may be set so that the NOx emission amount does not exceed the allowable amount.

  In the abnormality detection control, when an affirmative determination is made in the process of step S200 (step S200: YES), the process of step S203 may be executed without executing the process of step S202 after executing the process of step S201. . That is, when the abnormality detection control is started, the throttle valve 31 may always be controlled to be fully opened regardless of the opening degree of the throttle valve 31.

  When executing the abnormality detection process by the abnormality detection unit 78, the opening degree θt of the throttle valve 31 may not necessarily be controlled to be equal to or larger than the predetermined opening degree θa. In this case, a series of processes related to the abnormality detection control can be performed as shown in the flowchart of FIG.

  As shown in FIG. 6, when this series of processing is executed, the control device 70 first determines whether or not the operating state of the internal combustion engine is idling (step S600). If it is determined in step S600 that the internal combustion engine is idling (step S600: YES), the EGR opening degree control unit 82 performs energization control to the EGR valve 63 and controls the EGR valve 63. The fully open state is controlled (step S601).

  Thereafter, the pulsation detecting unit 75 detects intake air pulsation upstream of the throttle valve 31 in the intake passage (step S602). In this process, the output signal of the air flow meter 92 is input to the pulsation detector 75. The detection mode of intake pulsation in the process of step S602 is the same as the detection mode of intake pulsation in step S205 of the above embodiment. Thereafter, the process proceeds to step S603, and the trajectory length calculation unit 77 calculates the trajectory length ΣTL of the pulsation per 720 ° CA from the pulsation of the intake air detected by the pulsation detection unit 75. The calculation mode of the trajectory length ΣTL in the process of step S603 is the same as the calculation mode of the trajectory length ΣTL in step S206 of the above embodiment.

  Next, the process proceeds to step S604, and the opening degree determination unit 79 of the abnormality detection unit 78 determines whether or not the opening degree θt of the throttle valve 31 is equal to or larger than the predetermined opening degree θa, and executes the abnormality detection process. It is determined whether the condition is met (step S604). In the process of step S604, when it is determined that the opening degree θt of the throttle valve 31 is equal to or larger than the predetermined opening degree θa (step S604: YES), it is assumed that the condition for executing the abnormality detection process is satisfied, and the abnormality detection unit 78 Performs the processing from step S605 onward, and performs abnormality detection of the PCV piping 40.

  In the process of step S605, the execution counter is incremented. Thereby, the number of times of performing the abnormality detection process is counted. Thereafter, the process proceeds to step S606, and the provisional determination execution unit 81 determines whether the trajectory length ΣTL of the intake pulsation is equal to or less than the determination value stored in the determination value storage unit 80. In this process, when it is determined that the trajectory length ΣTL of the intake pulsation is equal to or smaller than the determination value (step S606: YES), the process proceeds to step S607, and the abnormality detection unit 78 increments the abnormality counter. The abnormality counter is a counter that indicates the number of times that the PCV pipe 40 is provisionally determined to be detached from at least one of the cylinder head cover 26 and the intake pipe 30. Thereafter, the process proceeds to step S608.

  When it is determined in step S606 that the intake pulsation trajectory length ΣTL exceeds the determination value (step S606: NO), the process proceeds to step S608 without incrementing the abnormality counter.

  In the process of step S608, it is determined whether or not the execution counter is greater than or equal to a threshold value. For example, 100 is set as the threshold. When the execution counter reaches the threshold value (step S608: YES), the abnormality detection unit 78 next detects an abnormality in the PCV piping 40 (step S609). The abnormality detection method in step S608 is the same as the abnormality detection method in step S212 of the above embodiment. Thereafter, the process proceeds to step S610, the execution counter and the abnormality counter are reset, and the series of processes relating to the abnormality detection control is terminated.

  If the execution counter has not reached the threshold value in the process of step S608 (step S608: NO), the series of processes related to the abnormality detection control is terminated without executing the subsequent processes. Thus, the abnormality counter is held until the execution counter reaches the threshold value, and the number of times that the abnormality is detected temporarily in the PCV piping 40 is counted each time the abnormality detection processing by the abnormality detection unit 78 is executed. The processing from step S604 to step S610 corresponds to abnormality detection processing.

  When the control device 70 determines that the internal combustion engine is not idling (step S600: NO), and the opening degree θt of the throttle valve 31 is less than the predetermined opening degree θa, the condition for executing the abnormality detection process is If it is determined that it has not been established (step S604: NO), a series of processing relating to abnormality detection control is terminated without performing the subsequent processing. When the series of processes related to the abnormality detection control is thus completed, the EGR opening degree control unit 82 sets the opening degree of the EGR valve 63 to the original opening degree before increasing the opening degree of the EGR valve 63 in the process of step S601. Return to.

  Even with such a configuration, the abnormality detection process for detecting an abnormality in the PCV pipe 40 can be performed on condition that the opening degree θt of the throttle valve 31 is equal to or larger than the predetermined opening degree θa. Therefore, the same effect as (1) can be obtained.

  When a series of processes in the abnormality detection control is completed, the predetermined opening determined based on the operating state of the internal combustion engine is not performed, but the opening of the throttle valve 31 or the opening of the EGR valve 63 is not returned to the opening before the increase. You may make it control every time.

  When the abnormality detection unit 78 determines that an abnormality has occurred in the PCV piping 40, it stores that fact. In place of or in addition to such a configuration, a control lamp for an internal combustion engine is provided such that a notification lamp is provided in a driver's seat of a vehicle and the abnormality detection unit 78 turns on the notification lamp when an abnormality of the PCV piping 40 is detected. The driver or the operator may be notified of the abnormality without accessing the 70.

  The trajectory length calculation unit 77 calculates the trajectory length ΣTL per 720 ° CA, but the calculation mode of the trajectory length ΣTL can be changed as appropriate. For example, the trajectory length ΣTL per 360 ° CA that reflects the effect of two cylinders 11A may be calculated, or the trajectory length ΣTL per 180 ° CA that reflects the effect of one cylinder 11A is calculated. May be.

  Although an example in which the detected intake pulsation trajectory length ΣTL is calculated as a correlation value correlated with the magnitude of the intake pulsation has been described, the calculated correlation value is not limited to the trajectory length ΣTL. For example, the amplitude of the pulsation of intake air and the average value of the amplitude also increase as the intake pulsation increases. Therefore, the correlation value calculation unit may calculate the amplitude in the intake pulsation or the average value of the amplitude as the correlation value. When calculating the amplitude in the intake pulsation, for example, the difference between the maximum amplitude and the minimum amplitude among the intake pulsations at 720 ° CA may be taken. In the case of four cylinders, the pulsation for one cylinder may be taken. Of the reflected intake pulsation at 180 ° CA, the difference between the maximum amplitude and the minimum amplitude may be taken.

  In the abnormality detection control in each of the above embodiments, the abnormality detection process is performed under the condition that the opening degree θt of the throttle valve 31 is equal to or greater than the predetermined opening degree θa. Not limited to. For example, in the abnormality detection device for an internal combustion engine, a pulsation detection process (for example, a process from step S200 to step S206 in FIG. 2) and an abnormality detection process (for example, from step S207 to step S213 in FIG. 2) are detected. Can also be executed as independent controls. That is, it is possible to repeatedly execute the pulsation detection process every predetermined first period and to repeatedly execute the abnormality detection process every second period different from the first period. In this case, in the pulsation detection process, the magnitude of the intake pulsation when the opening degree θt of the throttle valve 31 is equal to or larger than the predetermined opening degree θa is detected and stored. In the abnormality detection process, the abnormality detection process is executed based on the magnitude of the intake pulsation stored in the pulsation detection process. In such a configuration, the abnormality detection process can be started regardless of the opening degree θt of the throttle valve 31. Therefore, for example, even when the opening degree θt of the throttle valve 31 is less than the predetermined opening degree θa at the start timing of the abnormality detection process, abnormality detection is performed based on the magnitude of the intake pulsation stored in the pulsation detection unit. Thus, it is possible to detect an abnormality based on the magnitude of the intake pulsation when the opening θt of the throttle valve 31 is equal to or larger than the predetermined opening θa.

  Although one end of the PCV pipe 40 is connected to the cylinder head cover 26 of the engine body 10, if the blow-by gas can flow from the crank chamber 18 to the intake passage through the PCV pipe 40, for example, the crankcase 16, etc. The PCV pipe 40 may be connected to this part.

  Although the other end of the PCV pipe 40 is connected to the intake upstream side of the throttle valve 31 in the intake passage, the other end of the PCV pipe 40 may be connected to the intake downstream side of the throttle valve 31 in the intake passage.

  The throttle opening calculation unit 71 calculates the opening of the throttle valve 31 based on the output signal from the throttle sensor 91, but the configuration for calculating the opening of the throttle valve 31 is not limited to this. For example, since the opening degree of the throttle valve 31 and the amount of intake air passing through the air flow meter 92 are correlated, the opening degree of the throttle valve 31 can be calculated based on an output signal from the air flow meter 92.

  -Although the example which applied the control apparatus of the internal combustion engine to the inline 4 cylinder internal combustion engine was demonstrated, the control apparatus of an internal combustion engine is not restricted to such a thing. For example, even in the case of an in-line 6-cylinder internal combustion engine or a V-type internal combustion engine, the same configuration as in the above embodiment can be adopted. The same applies to an internal combustion engine with a supercharger in which a compressor of the supercharger is disposed downstream of the throttle valve 31 in the intake passage. Further, although the diesel type internal combustion engine has been described as an example of the internal combustion engine, the same configuration as that of the above embodiment can be applied even to a gasoline type internal combustion engine. In the case of a gasoline internal combustion engine, when the opening degree of the throttle valve 31 is increased when the abnormality detection process is performed, the occurrence of misfire may be suppressed by increasing the fuel injection amount.

  DESCRIPTION OF SYMBOLS 10 ... Engine main body, 11 ... Cylinder block, 11A ... Cylinder, 12 ... Piston, 13 ... Connecting rod, 14 ... Crankshaft, 14A ... Arm part, 14B ... Shaft part, 15 ... Timing rotor, 16 ... Crankcase, 17 ... Oil pan, 18 ... crank chamber, 19 ... oil supply system, 19A ... oil supply passage, 19B ... oil pump, 20 ... cylinder head, 21 ... combustion chamber, 22 ... intake port, 23 ... exhaust port, 24 ... intake valve, 25 ... Exhaust valve, 26 ... Cylinder head cover, 27 ... Accommodating chamber, 28 ... Valve mechanism, 29 ... Oil return passage, 30 ... Intake pipe, 31 ... Throttle valve, 32 ... Throttle motor, 40 ... PCV piping, 50 ... Exhaust Pipe, 60 ... EGR passage, 61 ... EGR passage, 62 ... EGR cooler, 63 ... EGR valve, 70 Control device 71 ... Throttle opening calculator 72 ... Throttle opening controller 73 ... Rotational speed calculator 74 ... Operating state detector 75 ... Pulsation detector 76 ... Band pass filter 77 ... Trace length calculation 78: Abnormality detection unit, 79 ... Opening determination unit, 80 ... Determination value storage unit, 81 ... Temporary determination execution unit, 82 ... EGR opening control unit, 90 ... Crank angle sensor, 91 ... Throttle sensor, 92 ... Air flow meter, 93 ... accelerator sensor, 94 ... vehicle speed sensor.

Claims (4)

A throttle valve arranged in the intake passage of the internal combustion engine;
A pulsation detection sensor disposed upstream of the throttle valve in the intake passage;
One end is connected to the engine body of the internal combustion engine, the other end is connected to the intake downstream side of the pulsation detection sensor in the intake passage, and PCV for flowing blow-by gas from the engine body to the intake passage Applied to an internal combustion engine with piping,
An abnormality detection process is a process for detecting a detachment of the PCV pipe from the engine body or the intake passage based on the magnitude of the pulsation of the intake air flowing through the intake passage based on an output signal from the pulsation detection sensor. Equipped with an abnormality detection unit to perform,
The abnormality detection unit is an abnormality detection apparatus for an internal combustion engine that performs the abnormality detection process based on the magnitude of the pulsation in a state where the opening degree of the throttle valve is equal to or larger than a predetermined opening degree. When performing the abnormality detection process by the abnormality detection unit, a throttle opening degree control unit that controls the opening degree of the throttle valve to be equal to or greater than the predetermined opening degree when the opening degree of the throttle valve is less than the predetermined opening degree. The abnormality detection device for an internal combustion engine according to claim 1. The internal combustion engine includes an EGR passage that communicates an exhaust passage of the internal combustion engine and an intake downstream side of a throttle valve in the intake passage;
An EGR valve disposed in the EGR passage,
The abnormality detection device includes an EGR opening degree control unit that controls the opening degree of the EGR valve,
The abnormality detection device for an internal combustion engine according to claim 1, wherein the EGR opening degree control unit increases the opening degree of the EGR valve when the abnormality detection process is performed by the abnormality detection unit. The said abnormality detection part performs the said abnormality detection process based on the magnitude | size of the said pulsation when the driving | running state of the said internal combustion engine is idle driving | operation. The internal combustion engine of Claim 1 characterized by the above-mentioned. Anomaly detection device.