JP5115327B2 - 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 only for determining whether 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 object, the present invention provides 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 . Abnormality diagnosis apparatus, an intake amount adjusting means for adjusting an intake air amount of the internal combustion engine to adjust an idle rotational speed of the internal combustion engine, and control means for feedback controlling the intake air amount adjusting means to a predetermined target idle rotational speed, and change means for the opening of the flow control valve in feedback control of the intake air quantity adjusting means by the control means a predetermined amount is changed, when the opening degree of the flow control valve by a predetermined amount changes, the intake air quantity adjusting means by the control means When the absolute value of the change amount of the feedback control amount is equal to or greater than a predetermined determination value, it is determined that there is no abnormality in the blow-by gas processing mechanism, and when it is less than the predetermined determination value, there is an abnormality in the blow-by gas processing mechanism. Determination means for determining.

The present invention also provides an abnormality diagnosis method for a blow-by gas processing mechanism that re-feeds blow-by gas of an internal combustion engine having an intake air amount adjusting means for adjusting the intake air amount of the internal combustion engine to an intake passage via a flow control valve. To do. In the abnormality diagnosis method , the intake air amount adjusting means is feedback-controlled so that the rotation speed of the internal combustion engine matches a predetermined target idle rotation speed, and the opening degree of the flow control valve is changed by a predetermined amount during the feedback control. If the absolute value of the change amount of the feedback control amount of the intake air amount adjusting means when the valve opening is changed by a predetermined amount is greater than or equal to a predetermined determination value, it is determined that there is no abnormality in the blow-by gas processing mechanism, If it is less than this determination value, it is determined that there is an abnormality in the blow-by gas processing mechanism.

  While the adjustment means is feedback controlled so that the rotation speed of the internal combustion engine matches a predetermined target idle rotation speed, the opening degree of the flow rate control valve is changed by a predetermined amount, and the amount of change in the feedback control amount of the adjustment means at that time By determining whether there is an abnormality in the blow-by gas processing mechanism, an abnormality diagnosis can be performed without using a sensor 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 an 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 injecting fuel from the fuel injector 3 into the air sucked into the combustion chamber from the intake passage 2 and burning the generated air-fuel mixture. 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. The intake throttle 5 is closed when the internal combustion engine 1 is idling, and air for idling is sucked into the combustion chamber of the internal combustion engine 1 from the intake passage 2 via 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 drawn into a combustion chamber formed in the cylinder block 1A from an intake port 6 provided in the cylinder head 1B. The air-fuel mixture burns in the combustion chamber and generates 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 mixture of blowby gas and air is re-supplied to the intake passage 2 downstream of the throttle 5 through the blowby 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.

  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. 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 controlled by adjusting the opening degree of the PCV valve 10.

  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 for idle speed control of the internal combustion engine 1 executed by the engine controller 20 in a separate routine, and is set to 1 when the internal combustion engine 1 is performing idle operation, and is performing 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 S12, maintains the opening of the PCV valve 10 at the normal control opening, and repeats the determination in step S1.

  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 S11 in the same manner as in step S12, and opens the PCV valve 10 for normal control. The determinations of steps S1 and S2 are repeated while maintaining each time.

  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 stores the opening of the PCV valve 10 at that time and the feedback correction value for idle speed control in the RAM in step S4. Further, the diagnosis start flag is set to 1.

  The feedback correction value for the idle speed control is based on the difference or ratio between the idle rotational speed and the idle target rotational speed by the engine controller 20 so that the idle rotational speed of the internal combustion engine 1 matches a predetermined idle target rotational speed. This is a correction value for feedback control of the opening degree of the idle speed control valve 12.

  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 the increasing direction or the decreasing direction.

  In step S6, 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 S6 is positive, the engine controller 20 performs the process in step S7. If the determination in step S6 is negative, that is, if the amount of change in the opening of the PCV valve 10 is less than the amount of change in the opening that is the diagnostic target, the engine controller 20 continues to step until the determination in step S6 turns positive. Repeat the process of S1-S5.

  In step S7, the engine controller 20 compares the absolute value of the correction value difference between the feedback correction value for the idle speed control at the start of diagnosis and the feedback correction value for the current idle speed control with a predetermined determination value.

  If the absolute value of the correction value difference is greater than or equal to the determination 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 S8. On the other hand, if the absolute value of the correction value difference is less than the determination value, the engine controller 20 displays on the display device that an abnormality has occurred in the blow-by gas processing mechanism in step S9.

  After the process of step S8 or S9, the engine controller 20 resets the diagnosis start flag to zero in step S10, returns the opening degree of the PCV valve 10 to the normal control opening degree, and then ends the routine.

  To summarize the above routine, when the PCV valve 10 is changed equal to the diagnostic target opening change amount, if the difference in the correction value of the idle speed feedback control correction of the idle speed control valve 12 is equal to or greater than a predetermined determination value, If there is no abnormality in the blow-by gas processing mechanism and the correction value difference does not satisfy the predetermined determination value, it is determined that an abnormality has occurred in the blow-by gas processing mechanism. When the opening degree of the PCV valve 10 changes, the blow-by gas flow rate changes. Correspondingly, the feedback correction value for idle speed control should also change. Even if the opening degree of the PCV valve 10 is changed to the diagnosis target opening degree change amount, if the correction value difference of the idle speed feedback control correction does not satisfy the predetermined judgment value, the expected change in the flow rate of blow-by gas Is not shown. 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 detecting the negative pressure downstream of the PCV valve 10 using the pressure sensor.

  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, regardless of the opening degree of the PCV valve 10, the correction value of the idle speed feedback control when the opening degree change amount of the PCV valve 10 reaches the opening degree change amount targeted for diagnosis, and the PCV valve 10 The presence or absence of the blow-by gas processing mechanism is determined from the correction value difference with the correction value of the idle speed feedback control before the opening degree change. That is, the opening degree change of the PCV valve 10 is started from an arbitrary opening degree.

  On the other hand, in this routine, the opening degree change of the PCV valve 10 is always started from a predetermined diagnosis start target opening degree.

  In this routine, steps that perform the same processing as in the routine of FIG.

  Steps S1, S2, S11, and S12 are the same as the routine of FIG. 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 target attainment flag is 1 in step S101. The target reaching flag is a flag indicating whether or not the opening degree of the PCV valve 10 has reached the target opening degree for starting diagnosis. The initial value of the target attainment flag is zero. Therefore, when the determination in step S101 is first executed after the routine execution is started, the determination result is always negative. In this case, the engine controller 20 performs the processes after step S3.

  In step S3, the engine controller 20 determines whether or not the diagnosis start flag is zero. If the diagnosis start flag is not zero, the engine controller 20 skips step S102 and performs step S103. It should be noted that the initial value of the diagnosis start flag is zero. Therefore, when the determination in step S3 is first performed after the execution of the routine is started, the diagnosis start flag is necessarily zero, and the process of step S102 is always performed. Is done.

  In step S102, the engine controller 20 sets a diagnosis start flag to 1.

  In step S103, the engine controller 20 gradually changes the opening of the PCV valve 10 by a predetermined amount toward the diagnosis start target opening.

  In the next step S104, the engine controller 20 determines whether or not the opening of the PCV valve 10 has reached the diagnosis start target opening.

  If the opening degree of the PCV valve 10 has reached the diagnosis start target opening degree, the engine controller 20 stores the correction value of the idle speed feedback control at that time in the RAM in step S105. Also, the target achievement flag is set to 1. After the process of step S105, the engine controller 20 performs the process of step S5. Even when it is determined in step S101 that the target arrival flag is not zero, the engine controller 20 performs the process of step S5.

  In step S5, the engine controller 20 gradually changes the opening of the PCV valve 10 from the diagnosis start target opening by a predetermined amount.

  In the next step S106, the engine controller 20 determines whether or not the difference between the diagnosis start target opening of the PCV valve 10 and the current opening of the PCV valve 10 has reached the diagnosis permission opening change amount. If the opening degree difference of the PCV valve 10 has not reached the diagnosis permission opening degree change amount, the engine controller 20 repeats the processing from step S1 until the opening degree difference of the PCV valve 10 reaches the diagnosis permission opening degree change amount.

  When the opening difference of the PCV valve 10 reaches the diagnosis permission opening change amount in step S106, the engine controller 20 determines in step S7 the feedback correction value of the idle speed control at the start of diagnosis and the feedback correction value of the current idle speed control. The absolute value of the difference between the correction values is compared with a predetermined determination value.

  The subsequent processing in steps S8 to S10 based on the absolute value of the correction value difference is the same as the routine of FIG.

  In this embodiment, unlike the routine of FIG. 3, the opening degree of the PCV valve 10 is always changed from a predetermined diagnosis start target opening degree, and the presence or absence of abnormality in the blow-by gas processing mechanism is determined for the idle speed control during this change. Judgment is based on the difference in correction values. Therefore, the determination is always performed under the same conditions, and higher determination accuracy can be expected. Furthermore, by always performing the determination under the same conditions, an accurate determination result can always be obtained without being influenced by the opening degree-flow rate characteristic of the PCV valve 10.

  As described above, according to the present invention, the presence or absence of abnormality of the blow-by gas processing mechanism is determined from the correction value difference of the idle speed control according to the predetermined opening change of the PCV valve 10 without using the pressure sensor. The presence or absence of abnormality of the blow-by gas processing mechanism can be determined without using a dedicated pressure sensor.

  In the routines of FIGS. 3 and 4, whether or not there is an abnormality in the blow-by gas processing mechanism is determined only when the cooling water temperature of the internal combustion engine 1 exceeds the diagnosis-permitted water temperature. By limiting the presence / absence of abnormality of the blow-by gas processing mechanism to the temperature environment above the diagnosis-permitted water temperature in this way, the gasoline concentration in the blow-by gas is limited to a certain range. Therefore, it is possible to estimate the amount of air contained in the blow-by gas from the flow rate, and by controlling the air-fuel ratio of the internal combustion engine 1 based on the estimated amount of air, the accuracy of the air-fuel ratio control can be improved.

  In each of the above embodiments, the idle speed control valve 12 constitutes an adjusting means, and the engine controller 20 constitutes a control means, a changing means, a determining means, a limiting means, and an opening degree adjusting means. More specifically, another routine executed by the engine controller 20 corresponds to the control means, and steps S5 and S6 of the routines shown in FIGS. 3 and 4 executed by the engine controller 20 correspond to the changing means. S9 corresponds to the determining means, step S2 corresponds to the limiting means, and steps S103 and S104 correspond to the opening degree adjusting means.

  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, in each of the embodiments described above, a parameter necessary for control is detected using a sensor. However, the present invention does not depend on a parameter acquisition method, and any parameter that executes a claimed control using a parameter. It can also be applied to abnormality diagnosis of blow-by gas processing mechanisms.

  Each of the above embodiments is an embodiment in which the present invention is applied to the internal combustion engine 1 provided with the bypass passage 11 and the idle speed control valve 12. However, the intake throttle is not provided with the bypass passage 11 and the idle speed control valve 12. The present invention can also be applied to an internal combustion engine that controls the amount of intake air during idle operation. In that case, the presence or absence of abnormality of the blow-by gas processing mechanism may be determined from the difference in feedback correction value of the opening of the intake throttle 5 in accordance with a predetermined opening change of the PCV valve 10 during idle operation.

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.

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 Throttle 5 Intake throttle 6 Intake port 7 Cylinder 8 Air duct 9 Blow-by gas passage 10 PCV 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

Claims (6)

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,
And intake air amount adjusting means for adjusting the intake air amount of the internal combustion engine to adjust an idle rotational speed of the internal combustion engine, and control means for feedback controlling the intake air amount adjusting means to a predetermined target idle rotational speed, the intake air quantity by the control means and change means for the opening of the flow control valve in feedback control of the adjustment means varies the predetermined amount, in the case where the opening degree of the flow control valve by a predetermined amount changes, the change of the feedback control amount of the intake amount adjustment means by the control means Determining means for determining that there is no abnormality in the blow-by gas processing mechanism when the absolute value of the quantity is equal to or greater than a predetermined determination value, and determining that there is an abnormality in the blow-by gas processing mechanism if it is less than the predetermined determination value ; An abnormality diagnosis device for a blow-by gas processing mechanism. The abnormality diagnosis device for a blow-by gas processing mechanism according to claim 1, wherein the intake air amount adjusting means is a throttle for adjusting an intake air amount of the internal combustion engine. The abnormality diagnosis device for a blow-by gas processing mechanism according to claim 1, wherein the intake air amount adjusting means is an idle speed control valve provided in a bypass passage that bypasses the throttle of the internal combustion engine.   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 4. The abnormality diagnosis device for a blowby gas processing mechanism according to any one of Items 3 to 4.   2. The opening adjusting means for adjusting the opening of the flow control valve to a predetermined diagnosis start target opening prior to the start of change in the opening of the flow control valve by the changing means. The abnormality diagnosis apparatus for a blow-by gas processing mechanism according to claim 4. In the abnormality diagnosis method of the blow-by gas processing mechanism for re-supplying the blow-by gas of the internal combustion engine provided with the intake air amount adjusting means for adjusting the intake air amount of the internal combustion engine to the intake passage through the flow control valve,
The intake air amount adjusting means is feedback-controlled so that the rotation speed of the internal combustion engine matches a predetermined target idle rotation speed, and the opening degree of the flow control valve is changed by a predetermined amount during the feedback control, and the opening degree of the flow control valve is adjusted. When the absolute value of the change amount of the feedback control amount of the intake air amount adjusting means when the predetermined amount is changed is greater than or equal to a predetermined determination value, it is determined that there is no abnormality in the blow-by gas processing mechanism, and is less than the predetermined determination value and judging that there is an abnormality in the blow-by gas processing mechanism in the case, the abnormality diagnostic method of the blow-by gas processing mechanism.

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