JP5109802B2 - Abnormality diagnosis apparatus and method for blow-by gas processing mechanism - Google Patents

Description

  The present invention relates to an abnormality diagnosis of a blow-by gas processing mechanism for re-supplying blow-by gas of an internal combustion engine to intake air.

  An apparatus for diagnosing the presence or absence of an abnormality in a blow-by gas processing mechanism for re-supplying blow-by gas of an internal combustion engine to an intake passage is known (see Patent Document 1).

  The blow-by gas processing mechanism is configured as follows. That is, the blow-by gas leaked from the piston sliding portion of the internal combustion engine to the crankcase is guided into the head cover of the engine and mixed with the air flowing in from the air duct. This air-fuel mixture is re-supplied to the intake passage downstream of the intake throttle of the engine via the blow-by gas passage.

  In order to control the flow rate of blow-by gas, a PCV (Positive Crankcase Ventilation) valve, which is a negative pressure responsive flow control valve, is provided in the blow-by gas passage. The PCV valve is a valve that reduces the flow area as the intake negative pressure of the engine increases. In an internal combustion engine, the suction negative pressure is large during idling when the intake throttle is throttled, and the suction negative pressure is small during acceleration. Therefore, the distribution area is reduced during idling of the engine, and the distribution area is increased during acceleration.

The prior art determines whether there is an abnormality in the blow-by gas processing mechanism by comparing a negative pressure detected by a pressure sensor provided downstream of the PCV valve with a predetermined pressure.
Japanese Patent Laid-Open No. 10-184336

  In the prior art, a pressure sensor must be provided in the blow-by gas passage only for determining whether or not there is an abnormality in the blow-by gas processing mechanism. Further, it is necessary to execute an independent abnormality diagnosis routine based on the pressure detected by the pressure sensor. However, such a request increases the cost of abnormality diagnosis.

  Accordingly, an object of the present invention is to detect an abnormality in a blow-by gas processing mechanism without using a sensor.

In order to achieve the above-described problems, the present invention provides an abnormality diagnosis device for a blow-by gas processing mechanism that re-feeds blow-by gas of an internal combustion engine to an intake passage via a flow control valve. Change means for changing the opening of the control valve by a predetermined amount, torque compensating means for compensating for fluctuations in the output of the internal combustion engine when the opening of the flow control valve is changed by a predetermined amount, by correcting the ignition timing of the internal combustion engine, An operating parameter detecting means for detecting an operating parameter of the internal combustion engine different from the ignition timing of the internal combustion engine, and a changing means while compensating for fluctuations in the output of the internal combustion engine by the output compensating means during idle operation of the internal combustion engine. Based on the amount of change in operating parameters when the opening of the flow control valve is changed by a predetermined amount, it is determined whether there is an abnormality in the blow-by gas processing mechanism. And a judging means for.

The present invention also provides an abnormality diagnosis method for a blow-by gas processing mechanism for re-supplying blow-by gas of an internal combustion engine to an intake passage via a flow control valve, and changes the opening of the flow control valve by a predetermined amount during idling operation of the internal combustion engine. To compensate for fluctuations in the output of the internal combustion engine when the flow control valve opening is changed by a predetermined amount by correcting the ignition timing of the internal combustion engine, and to compensate for fluctuations in the output of the internal combustion engine during idling of the internal combustion engine However, when the opening degree of the flow rate control valve is changed by a predetermined amount, a change amount of the operation parameter different from the ignition timing of the internal combustion engine is detected, and an abnormality of the blow-by gas processing mechanism is detected based on the change amount of the operation parameter. The presence or absence of is determined.

During idle operation of the internal combustion engine, determine whether there is an abnormality in the blow-by gas processing mechanism based on the amount of change in the operating parameter when the opening of the flow control valve is changed by a predetermined amount while compensating for fluctuations in the output of the internal combustion engine By doing so, an abnormality diagnosis can be performed without providing a pressure sensor in the blow-by gas passage and without impairing the drivability of the internal combustion engine.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 shows a schematic longitudinal section of a spark ignition type multi-cylinder internal combustion engine 1 for a vehicle for explaining an example of the configuration of a blow-by gas processing mechanism to which the present invention is applied.

  The internal combustion engine 1 reciprocates the piston 4 by burning an air-fuel mixture of air sucked into the combustion chamber of each cylinder from the intake passage 2 via the intake manifold 25 and the intake port 6 and fuel injected from the fuel injector 3. Exercise.

  The intake passage 2 is provided with an intake throttle 5 for adjusting the intake flow rate. Further, a bypass passage 11 that bypasses the intake throttle 5 and an idle speed control valve 12 that adjusts the flow rate of the bypass passage 11 are provided. During idling operation of the internal combustion engine 1, the intake throttle 5 is closed, and air for idling operation is sucked from the intake passage 2 into the combustion chamber of the internal combustion engine 1 through the bypass passage 11 and the idle speed control valve 12.

  The internal combustion engine 1 includes a cylinder block 1A housing the piston 4, a cylinder head 1B positioned above the cylinder block 1A, a head cover 1D covering the cylinder head 1B, and a crankcase 1C positioned below the cylinder block. Divided.

  The piston 4 is accommodated in a cylinder 7 formed in the cylinder block 1A, and the combustion chamber is formed above the piston 4 of the cylinder. The air-fuel mixture is ignited by the spark of the spark plug 26 and burned in the combustion chamber to generate high-pressure combustion gas. The combustion gas is discharged from the exhaust passage after the piston 4 is pushed down.

  A part of the high-pressure combustion gas in the combustion chamber flows out as blow-by gas into the lower crankcase 1 </ b> C through the sliding gap between the piston 4 and the cylinder 7.

  The internal combustion engine 1 guides this blow-by gas to the head cover 1 </ b> D and mixes it with air guided from the intake passage 2 upstream of the throttle 5 through the air duct 8. The air-fuel mixture of blow-by gas and air is supplied again to the intake manifold 25 downstream of the throttle 5 through the blow-by gas passage 9. A PCV valve 10 is provided in the blow-by gas passage 9. In the following description, the mixture of blowby gas and air is also simply referred to as blowby gas.

  The blow-by gas is mixed with the intake air of the intake passage 2 by the intake manifold 25 and then sucked into the combustion chamber from the intake port 6 of each cylinder.

  FIG. 2 shows a side view and a rear view including a partial longitudinal section of the PCV valve 10.

  The PCV valve 10 includes a port 16 communicating with the upstream side of the blowby gas passage 9 and a port 17 communicating with the blowby gas passage 9. An annular valve seat 22 is provided between the ports 16 and 17. The PCV valve 10 changes the flow cross-sectional area of blow-by gas when the valve body 18 driven by the solenoid 19 approaches or retracts from the valve seat 22.

  The present invention performs abnormality diagnosis of the blowby gas processing mechanism configured as described above.

  The abnormality diagnosis device for the blow-by gas processing mechanism includes an engine controller 20 that controls the operation of the internal combustion engine 1.

  The engine controller 20 receives a coolant temperature signal from a temperature sensor 21 that detects the coolant temperature of the internal combustion engine 1. Further, a pressure signal is input from a pressure sensor 23 that detects the pressure of the intake manifold 25 of the internal combustion engine 1. Further, a crank angle signal is input from the crank angle sensor 24 for a specific crank angle of the internal combustion engine 1. The engine controller 20 detects the rotational speed of the internal combustion engine 1 from the crank angle signal.

  The engine controller 20 adjusts the opening degree of the intake throttle 5 in accordance with the depression amount of the accelerator pedal provided in the vehicle. Further, when the internal combustion engine 1 is idling, the intake throttle 5 is closed, while the opening of the idle speed control valve 12 provided in the bypass passage 11 is adjusted so as to maintain the idling rotational speed of the internal combustion engine 1 at a predetermined speed. . Further, the blow-by gas flow rate is increased or decreased by changing the opening degree of the PCV valve 10. Further, the output fluctuation of the internal combustion engine 1 due to the increase / decrease in the blowby gas flow rate is compensated by adjusting the ignition timing of the spark plug 26.

  The engine controller 20 also feedback-controls the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber of the internal combustion engine 1 to a predetermined target air-fuel ratio through control of the fuel injection amount of the fuel injector 3 by a known method. .

  The engine controller 20 includes a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). It is also possible to configure the engine controller 20 with a plurality of microcomputers.

  FIG. 3 shows an abnormality diagnosis routine of the blow-by gas processing mechanism executed by the engine controller 20. The engine controller 20 executes this routine immediately after starting the internal combustion engine. When the routine is terminated during the operation of the internal combustion engine 1, the engine controller 20 does not execute this routine until the next start of the internal combustion engine 1.

  In step S1, the engine controller 20 determines whether or not the idle flag fIDLE is 1. The idle flag fIDLE is a flag used in the idle operation control of the internal combustion engine 1 executed by the engine controller 20 in a separate routine. The idle flag fIDLE is set to 1 when the internal combustion engine 1 performs the idle operation, and performs the non-idle operation. In some cases it is set to zero.

  If the idle flag fIDLE is not 1 in step S1, the engine controller 20 clears the diagnosis start flag in step S13, maintains the opening of the PCV valve 10 at the normal control opening, and ignites the PCV opening change torque. After completing the correction based on the timing, the determination in step S1 is executed again. The correction by the ignition timing of the PCV opening change torque will be described later. The engine controller 20 repeatedly executes the process of step S13 and the determination of step S1 until the idle flag fIDLE changes to 1.

  When the idle flag fIDLE turns to 1 in step S1, the engine controller 20 determines whether or not the cooling water temperature of the internal combustion engine 1 detected by the temperature sensor 21 in step S2 exceeds the diagnosis permission water temperature.

  If the cooling water temperature of the internal combustion engine 1 does not exceed the diagnosis permission water temperature in step S2, the engine controller 20 clears the diagnosis start flag in step S12 in the same manner as in step S13, and opens the PCV valve 10 for normal control. After the correction by the ignition timing of the PCV opening change torque is completed, the determinations in steps S1 and S2 are performed again. Finally, the process of step S12 and the determinations of steps S1 and S2 are repeated until the cooling water temperature of the internal combustion engine 1 exceeds the diagnosis permission water temperature in step S2.

  If the cooling water temperature of the internal combustion engine 1 exceeds the diagnosis permission water temperature in step S2, the engine controller 20 determines whether or not the diagnosis start flag is zero in step S3. If the diagnosis start flag is not zero, the engine controller 20 skips step S4 and performs step S5. Note that the initial value of the diagnosis start flag is zero. Therefore, when the determination in step S3 is first performed after the routine execution is started, the diagnosis start flag is necessarily zero, and the process of step S4 is always performed. Is done.

  If the diagnosis start flag is zero in step S3, the engine controller 20 determines the opening of the PCV valve 10 at that time and the pressure of the intake manifold 25 detected by the pressure sensor 23 in step S4 at the time of diagnosis start. Is stored in the RAM as the value of. Further, the diagnosis start flag is set to 1.

  In the next step S5, the engine controller 20 gradually changes the opening of the PCV valve 10 from the normal control opening by a predetermined amount. The direction of change may be either an increasing direction or a decreasing direction.

  In step S6, the engine controller 20 performs output compensation of the internal combustion engine 1 corresponding to the opening degree change of the PCV valve 10. When the opening degree of the PCV valve 10 is increased, the fuel content of the air-fuel mixture in the combustion chamber increases. For this reason, engine output increases. The engine controller 20 counteracts the ignition timing of the spark plug 26 to keep the engine output constant.

  In the next step S7, the engine controller 20 determines whether or not the opening degree change amount of the PCV valve 10 has reached a predetermined diagnostic opening degree change amount.

  If the determination in step S7 is positive, the engine controller 20 performs the process in step S8. If the determination in step S7 is negative, that is, if the amount of change in opening of the PCV valve 10 does not reach the amount of change in opening that is the diagnostic target, the engine controller 20 continues to step until the determination in step S7 turns positive. The process of S1-S6 is repeated.

  In step S8, the engine controller 20 compares the absolute value of the pressure difference between the pressure of the intake manifold 25 at the start of diagnosis stored in the RAM and the current pressure of the intake manifold 25 with a predetermined lower limit value.

  If the absolute value of the difference in intake manifold pressure is greater than or equal to the lower limit value, the engine controller 20 displays on the display device, for example, that there is no abnormality in the blow-by gas processing mechanism in step S9. If the absolute value of the difference in intake manifold pressure is less than the lower limit value, the engine controller 20 displays on the display device that an abnormality has occurred in the blow-by gas processing mechanism in step S10.

  As described above, in this embodiment, the pressure of the intake manifold is used as an engine operating parameter, and it is determined whether or not an abnormality has occurred in the blow-by gas processing mechanism based on the amount of change.

  After the process of step S9 or S10, the engine controller 20 resets the diagnosis start flag to zero in step S11, returns the opening of the PCV valve 10 to the normal control opening, and depends on the ignition timing of the PCV opening change torque. After the correction is finished, the routine is finished.

  To summarize the above routine, when the PCV valve 10 is changed equally to the diagnostic target opening change amount, the absolute value of the pressure difference between the intake manifold pressure at the start of diagnosis and the current intake manifold pressure is a predetermined lower limit. If the value is greater than or equal to the value, it is determined that there is no abnormality in the blow-by gas treatment mechanism, and that the blow-by gas treatment mechanism is abnormal if the absolute value of the pressure difference does not satisfy a predetermined lower limit. When the opening degree of the PCV valve 10 changes, the blow-by gas flow rate changes. Correspondingly, the pressure in the intake manifold 25 should also change. If the absolute value of the pressure difference between the intake manifold 25 before and after the change does not reach a predetermined lower limit even though the opening of the PCV valve 10 has changed to be equal to the diagnosis target opening change amount, the blow-by gas passage This means that the blowby gas flow rate of 9 has not changed as expected. That is, some abnormality has occurred in the blow-by gas processing mechanism including the PCV valve 10.

  In this way, it is possible to determine whether or not there is an abnormality in the blow-by gas processing mechanism without directly detecting the pressure in the blow-by gas passage 9.

  FIG. 4 shows another embodiment relating to an abnormality diagnosis routine of the blow-by gas processing mechanism executed by the engine controller 20.

  In the routine of FIG. 3, the engine controller 20 diagnoses whether there is an abnormality in the blow-by gas processing mechanism based on the pressure difference generated in the intake manifold 25 when the opening of the PCV valve 10 is changed by a predetermined amount. On the other hand, in this routine, the presence or absence of abnormality in the blow-by gas processing mechanism is diagnosed based on the speed difference generated in the rotational speed of the internal combustion engine 1 when the opening degree of the PCV valve 10 is changed by a predetermined amount.

  Specifically, in this routine, steps S104 and S108 are provided instead of steps S4 and S8 in FIG. The processing contents of the other steps are the same as the routine of FIG.

  In step S104, the engine controller 20 stores the opening degree of the PCV valve 10 at that time and the engine speed based on the crank angle signal of the crank angle sensor 24 in the RAM as respective values at the start of diagnosis. Further, the diagnosis start flag is set to 1.

  In step S108, the engine controller 20 compares the absolute value of the speed difference between the engine speed at the start of diagnosis stored in the RAM and the current engine speed with a predetermined upper limit value. In step S6, the engine controller 20 corrects the ignition timing of the internal combustion engine 1 so as to keep the output of the internal combustion engine 1 constant with respect to the opening degree change of the PCV valve 10. Nevertheless, the fact that a speed difference exceeding the upper limit value occurs in the engine rotation speed means that the blow-by gas flow rate does not show the assumed change. That is, it can be considered that some abnormality has occurred in the blow-by gas processing mechanism.

  Therefore, when the absolute value of the speed difference exceeds the upper limit value, the engine controller 20 determines that some abnormality has occurred in the blow-by gas processing mechanism, and that the blow-by gas processing mechanism has an abnormality in step S10. Is displayed on the display device. On the other hand, if the absolute value of the speed difference does not exceed the upper limit value, the engine controller 20 determines that there is no abnormality in the blow-by gas processing mechanism, and displays on the display device that there is no abnormality in the blow-by gas processing mechanism in step S9. To do.

  As described above, it is possible to determine whether or not there is an abnormality in the blow-by gas processing mechanism from the amount of fluctuation in the engine speed when the opening degree of the PCV valve 10 is changed.

  FIG. 5 shows still another embodiment relating to the abnormality diagnosis routine of the blow-by gas processing mechanism executed by the engine controller 20.

  The engine controller 20 feedback-controls the air-fuel ratio of the air-fuel mixture combusted in the combustion chamber to the target air-fuel ratio during operation of the internal combustion engine 1. This control is performed by, for example, detecting the air-fuel ratio of the burned air-fuel mixture from the oxygen concentration of the exhaust gas, and using the air-fuel ratio feedback correction coefficient calculated so that the detected air-fuel ratio is maintained in the vicinity of the target air-fuel ratio. This is executed by feedback control of the fuel injection amount of the injector 3. Since such air-fuel ratio feedback control is known, detailed description thereof is omitted.

  In this embodiment, an air-fuel ratio feedback correction coefficient used for air-fuel ratio feedback control is used as an operation parameter of the internal combustion engine 1.

  That is, in this routine, the engine controller 20 diagnoses whether there is an abnormality in the blow-by gas processing mechanism based on the amount of change that occurs in the air-fuel ratio feedback correction coefficient when the opening of the PCV valve 10 is changed by a predetermined amount.

  Specifically, in this routine, steps S114 and S118 are provided instead of steps S4 and S8 in FIG. The processing contents of the other steps are the same as the routine of FIG.

  In step S114, the engine controller 20 stores the opening degree of the PCV valve 10 and the air-fuel ratio feedback correction coefficient at that time in the RAM as respective values at the start of diagnosis. Further, the diagnosis start flag is set to 1.

  In step S118, the engine controller 20 compares the absolute value of the difference between the air-fuel ratio feedback correction coefficient at the start of diagnosis stored in the RAM and the current air-fuel ratio feedback correction coefficient with a predetermined lower limit value. # When the flow rate of blow-by gas changes, the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber changes. On the other hand, the engine controller 20 corrects the fuel injection amount of the fuel injector 3 so as to keep the air-fuel ratio in the vicinity of a predetermined target air-fuel ratio by air-fuel ratio feedback control executed in a separate routine. Therefore, the air-fuel ratio feedback correction coefficient used for this correction should change according to the flow rate change of the blow-by gas.

  Therefore, when the absolute value of the difference between the air-fuel ratio feedback correction coefficients is below the lower limit value, the engine controller 20 determines that some abnormality has occurred in the blow-by gas processing mechanism, and the blow-by gas processing mechanism has an abnormality in step S10. Is displayed on the display device. On the other hand, if the absolute value of the difference in the air-fuel ratio feedback correction coefficient does not fall below the lower limit value, the engine controller 20 determines that there is no abnormality in the blow-by gas processing mechanism, and that there is no abnormality in the blow-by gas processing mechanism in step S9. Is displayed on the display device.

  In this way, it is possible to determine whether or not there is an abnormality in the blow-by gas processing mechanism from the amount of change in the air-fuel ratio feedback correction coefficient when the opening of the PCV valve 10 is changed.

In each of the embodiments described above, steps S5 and S7 of the routines of FIGS. The spark plug 26 and step S6 of the routine of FIGS. 3 to 5 are output compensation means, step S8 of the routine of FIG. 3, step S108 of the routine of FIG. 4, and step S118 of the routine of FIG. Constitute. Further, in the embodiment of FIG. 3, the pressure sensor 23 constitutes an operation parameter detection means, in the embodiment of FIG. 4, the crank angle sensor 24 constitutes an operation parameter detection means, and in the embodiment of FIG. The air-fuel ratio feedback correction executed by 20 in another routine constitutes the operating parameter detection means. Further, step S2 of the routines of FIGS.

  As mentioned above, although this invention has been demonstrated through some specific embodiment, this invention is not limited to each said embodiment. Those skilled in the art can make various modifications or changes to these embodiments within the scope of the claims.

  For example, the present invention does not depend on the parameter acquisition method, and can be applied to abnormality diagnosis of any blow-by gas processing mechanism that executes the claimed control using the parameters.

  The present invention is also applicable to an internal combustion engine that does not include the bypass passage 11 and the idle speed control valve 12 and controls the intake air amount during idle operation by the intake throttle 5.

It is a schematic longitudinal cross-sectional view of the internal combustion engine explaining an example of a structure of the blowby gas processing mechanism to which this invention is applied. It is a longitudinal cross-sectional view of the PCV valve | bulb with which a blowby gas processing mechanism is provided. It is a flowchart explaining the abnormality diagnosis routine of the blowby gas processing mechanism which the controller by one Embodiment of this invention performs. It is a flowchart explaining the abnormality diagnosis routine of the blowby gas processing mechanism which the controller by another embodiment of this invention performs. It is a flowchart explaining the abnormality diagnosis routine of the blowby gas processing mechanism which the controller by another embodiment of this invention performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 1A Cylinder block 1B Cylinder head 1C Crankcase 1D Head cover 2 Intake passage 3 Fuel injector 4 Piston 5 Intake throttle 6 Intake port 7 Cylinder 8 Air duct 9 Blow-by gas passage 10 Valve 11 Bypass passage 12 Idle speed control valve 16 Port 17 port 18 Valve body 19 Solenoid 20 Engine controller 21 Temperature sensor 22 Valve seat 23 Pressure sensor 24 Crank angle sensor 25 Intake manifold 26 Spark plug

Claims (9)

In an abnormality diagnosis device for a blow-by gas processing mechanism for re-supplying blow-by gas of an internal combustion engine to an intake passage through a flow control valve,
Changing means for changing the opening of the flow control valve by a predetermined amount during idling of the internal combustion engine;
Output compensation means for compensating for fluctuations in the output of the internal combustion engine when the opening degree of the flow control valve is changed by a predetermined amount by correcting the ignition timing of the internal combustion engine;
An operation parameter detecting means for detecting an operation parameter of the internal combustion engine different from the ignition timing of the internal combustion engine;
During idle operation of the internal combustion engine, blow-by gas processing based on the amount of change in the operating parameter when the output compensation means compensates for fluctuations in the output of the internal combustion engine and the opening of the flow control valve by the changing means is changed by a predetermined amount. Determining means for determining the presence or absence of an abnormality in the mechanism;
An abnormality diagnosis device for a blow-by gas processing mechanism, comprising:   The abnormality diagnosis device for a blow-by gas processing mechanism according to claim 1, wherein the operating parameter is a pressure of an intake manifold of the internal combustion engine.   The blow-by gas processing mechanism according to claim 2, wherein the determination means is configured to determine that the blow-by gas processing mechanism is abnormal when the amount of change in the pressure of the intake manifold is less than a predetermined amount. Abnormality diagnosis device.   The abnormality diagnosis device for a blow-by gas processing mechanism according to claim 1, wherein the operating parameter is a rotation speed of the internal combustion engine.   The blow-by gas processing according to claim 4, wherein the determination means is configured to determine that the blow-by gas processing mechanism is abnormal when the amount of change in the rotational speed of the internal combustion engine exceeds a predetermined amount. Mechanism abnormality diagnosis device.   The abnormality diagnosis device for a blow-by gas processing mechanism according to claim 1, wherein the operating parameter is an air-fuel ratio feedback correction coefficient of the internal combustion engine.   The determination means is configured to determine that there is an abnormality in the blow-by gas processing mechanism when the amount of change in the air-fuel ratio feedback correction coefficient of the internal combustion engine is less than a predetermined amount. Abnormality diagnosis device for blow-by gas processing mechanism.   2. The apparatus according to claim 1, further comprising limiting means for limiting the determination of whether or not the blow-by gas processing mechanism is abnormal by the determination means when the cooling water temperature of the internal combustion engine is equal to or higher than a predetermined diagnosis-permitted water temperature. Item 8. The abnormality diagnosis device for a blowby gas processing mechanism according to any one of Items 7 to 9. In the abnormality diagnosis method of the blow-by gas processing mechanism for re-supplying the blow-by gas of the internal combustion engine to the intake passage via the flow control valve,
Changing the opening of the flow control valve by a predetermined amount during idling of the internal combustion engine;
Compensating for fluctuations in the output of the internal combustion engine when the opening degree of the flow control valve is changed by a predetermined amount by correcting the ignition timing of the internal combustion engine;
During idle operation of the internal combustion engine, the amount of change in the operation parameter different from the ignition timing of the internal combustion engine when the opening amount of the flow control valve is changed by a predetermined amount while compensating for fluctuations in the output of the internal combustion engine. Detect;
Determining whether there is an abnormality in the blow-by gas processing mechanism based on the amount of change in operating parameters;
An abnormality diagnosis method for a blowby gas processing mechanism.

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