JP6673790B2 - Engine system - Google Patents

Description

  The present invention relates to a blow-by gas reducing device for flowing blow-by gas generated in an engine to an intake passage and reducing the blow-by gas to the engine, an abnormality diagnostic device for diagnosing abnormality of the device, an air-fuel ratio control device for controlling an air-fuel ratio of the engine, The present invention relates to an engine system provided with:

  BACKGROUND ART Conventionally, as an abnormality diagnosis device of a blow-by gas reduction device, for example, a device described in Patent Literature 1 below is known. This device includes a crankcase and a head cover for accumulating blow-by gas generated by the engine, a blow-by gas passage for flowing blow-by gas from the head cover to an intake passage (surge tank downstream of the throttle valve), and an intake passage (from the throttle valve to the head cover). A fresh air introduction passage for introducing fresh air from the upstream and downstream of the air cleaner), a PCV valve for adjusting a flow rate of the blow-by gas flowing through the blow-by gas passage, and a gas pressure sensor for detecting a gas pressure in the blow-by gas passage. And an electronic control unit (ECU) for diagnosing an abnormality such as gas leakage or clogging in the blow-by gas passage based on the detection value of the sensor. The crankcase, the head cover, the blow-by gas passage, and the fresh air introduction passage constitute a blow-by gas reduction system that communicates with one to provide a flow toward the blow-by gas passage to the blow-by gas.

  However, in the above-described abnormality diagnosis device, since the gas pressure in the blow-by gas passage connected to the intake passage is detected by the gas pressure sensor, the detection value of the gas pressure sensor is easily affected by the pressure fluctuation of the intake passage, It has been difficult to make accurate abnormality diagnosis based on stable detection values.

  Therefore, in order to obtain a stable detection value of the pressure in the blow-by gas reduction system at the time of abnormality diagnosis, the air side (fresh air introduction passage side) of the blow-by gas reduction system is closed with an on-off valve, and the entire blow-by gas reduction system is closed. Introduce intake air pressure with little fluctuation. Then, an alternative is conceivable in which the gas pressure in the blow-by gas passage is detected by a gas pressure sensor, and an accurate abnormality diagnosis is performed based on the detected value.

JP-A-10-184336

  By the way, as one of the engine controls, a fuel injection amount is calculated based on an intake air amount detected by an air flow meter arranged in the vicinity of an air cleaner, and fuel is supplied to the engine based on the fuel injection amount. Air-fuel ratio control for controlling the fuel ratio is known. Therefore, it is conceivable to execute the above-described alternative in an engine system that executes this type of air-fuel ratio control.

  However, in the above alternative, when the on-off valve is closed to start the abnormality diagnosis, air in the blow-by gas reduction system that does not pass through the air flow meter is sucked into the engine through the blow-by gas passage and the surge tank. Will be. Therefore, the ratio of the actual air to the fuel injection amount calculated based on the detection value of the air flow meter increases, and the air-fuel ratio of the engine tends to lean. On the other hand, when the on-off valve is opened to end the abnormality diagnosis, a part of the air that has passed through the air flow meter is introduced into the blow-by gas reduction system via the fresh air introduction passage. Therefore, the ratio of the actual air to the fuel injection amount calculated based on the detection value of the air flow meter decreases, and the air-fuel ratio of the engine tends to become rich. As described above, at the start and end of the abnormality diagnosis, the air-fuel ratio may become lean or rich. Here, the ratio of the actual air that decreases at the end of the abnormality diagnosis is larger than the actual air ratio that increases at the start of the abnormality diagnosis.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an engine system capable of terminating an abnormality diagnosis of a blow-by gas reducing device without affecting air-fuel ratio control of an engine. Is to do.

In order to achieve the above object, an invention according to claim 1 is a blow-by gas reducing device for flowing blow-by gas generated in an engine to an intake passage and reducing the blow-by gas to the engine, and an abnormality diagnosis for diagnosing an abnormality of the blow-by gas reducing device. An engine system comprising: a device and an air-fuel ratio control device that controls an air-fuel ratio of the engine.The blow-by gas reducing device includes a blow-by gas storage unit for storing blow-by gas generated in the engine, and an intake passage. An intake air amount adjusting means provided in an intake passage for adjusting the amount of flowing intake air; and a blow-by for returning blow-by gas stored in a blow-by gas storage section to an engine by flowing the air into an intake passage downstream of the intake air amount adjusting means. Gas reducing passage and gas flow adjusting means for adjusting the flow of blow-by gas in the blow-by gas reducing passage A fresh air introduction passage connected to the intake passage upstream of the intake air amount adjusting means for introducing a part of the air flowing through the intake passage as fresh air to the blow-by gas storage section, and for opening and closing the fresh air introduction passage. Opening / closing means, the blow-by gas accumulating section, the blow-by gas returning passage and the fresh air introduction passage are connected to form one blow-by gas returning system, and the abnormality diagnosis device detects the pressure in the blow-by gas returning system. Pressure detection means, and abnormality diagnosis means for diagnosing an abnormality of the blow-by gas reduction system, wherein the abnormality diagnosis means closes the fresh air introduction passage by the opening / closing means during operation of the engine, and at that time, the pressure detection means The abnormality diagnosis is started based on the detected value of, and when ending the abnormality diagnosis, the fresh air introduction passage is opened by the opening / closing means, and the air-fuel ratio control device supplies fuel to the engine. Fuel supply means for supplying air, intake air amount detecting means for detecting the amount of intake air flowing through an intake passage upstream of a connection with the fresh air introduction passage, and intake air for adjusting the air-fuel ratio to a predetermined target value. Air-fuel ratio control means for calculating a control amount based on the detection value of the amount detection means, and controlling the fuel supply means based on the control amount, wherein the air-fuel ratio control means terminates the abnormality diagnosis. In addition, the control amount is corrected so that the air-fuel ratio likely to be enriched becomes the target value .

According to the configuration of the invention described above, the abnormality diagnosing means of the abnormality diagnosing device closes the fresh air introduction passage by the opening / closing means during operation of the engine, and at that time, the abnormality of the blow-by gas reduction system based on the detection value of the pressure detecting means. When the diagnosis is started and the abnormality diagnosis is completed, the opening / closing means opens the fresh air introduction passage. Therefore, when diagnosing an abnormality of the blow-by gas reduction system, the diagnosis is performed based on the stable pressure in the blow-by gas reduction system detected by the pressure detecting means. Further, the air-fuel ratio control means of the air-fuel ratio control device calculates a control amount based on the detection value of the intake air amount detection means to adjust the air-fuel ratio to a predetermined target value, and the abnormality diagnosis means ends the abnormality diagnosis. At this time, the calculated control amount is corrected so that the air-fuel ratio likely to become rich becomes the target value . Therefore, when the fresh air introduction passage is opened by the opening / closing means to end the abnormality diagnosis, a part of the intake air amount detected by the intake air amount detection means is introduced into the blow-by gas accumulation unit through the fresh air introduction passage and the engine is started. Even if the air-fuel ratio is likely to become rich, the air-fuel ratio is corrected so as to be a target value, and the enrichment is suppressed.

In order to achieve the above object, according to a second aspect of the present invention, in the first aspect of the invention, the air-fuel ratio control means is configured such that when the abnormality diagnosis device starts abnormality diagnosis, the air-fuel ratio is likely to become lean. The purpose is to correct the control amount so that is equal to the target value .

According to the configuration of the present invention, in addition to the operation of the invention according to claim 1, when the fresh air introduction passage is closed by the opening / closing means to start abnormality diagnosis, blow-by gas reduction not detected by the intake air amount detecting means. Even if the air of the system (mainly the blow-by gas storage unit) is sucked into the engine and the air-fuel ratio of the engine tends to lean, the air-fuel ratio is corrected to the target value and the leaning is suppressed.

  According to the first aspect of the present invention, it is possible to end the abnormality diagnosis of the blow-by gas reduction device without affecting the air-fuel ratio control of the engine, that is, without enriching the air-fuel ratio.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the blow-by gas reducing device can be used without affecting the air-fuel ratio control of the engine, that is, without making the air-fuel ratio lean. An abnormality diagnosis can be started.

1 is a schematic configuration diagram illustrating a gasoline engine system according to one embodiment. 6 is a flowchart showing the details of air-fuel ratio control according to one embodiment. 6 is a correction value map referred to for obtaining a correction value corresponding to an initial BGV pressure according to one embodiment. 6 is a time chart showing changes in various parameters when air-fuel ratio control is performed according to the embodiment. FIG. 1 is a schematic configuration diagram showing a flow of intake air and blow-by gas at the time of starting abnormality diagnosis of a BGV device in a gasoline engine system according to one embodiment. FIG. 1 is a schematic configuration diagram showing a flow of intake air and blow-by gas at the time of completion of abnormality diagnosis of a BGV device in a gasoline engine system according to one embodiment.

  Hereinafter, an embodiment of an engine system according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic configuration diagram of a gasoline engine system according to this embodiment. The engine 1 constituting this engine system includes an engine block 2 including a plurality of cylinders. A piston 3 is provided in each cylinder so as to be reciprocable. A crankcase 4 is provided below the engine block 2. The crankcase 4 is configured together with the oil pan 5. A crankshaft 6 is rotatably supported in the crankcase 4, and each piston 3 is connected to the crankshaft 6 via a connecting rod 7.

  In each cylinder, a combustion chamber 8 is formed above each piston 3. An intake port 9 and an exhaust port 10 are formed in the upper part of the engine block 2 corresponding to each combustion chamber 8. The intake port 9 is provided with an intake valve 11, and the exhaust port 10 is provided with an exhaust valve 12. Each of the intake valves 11 and each of the exhaust valves 12 are configured to open and close by a well-known valve train 13 in conjunction with the rotation of the crankshaft 6. When the intake valve 11 and the exhaust valve 12 open and close, air is sucked into the combustion chamber 8 from the intake port 9, and the exhaust gas after combustion is discharged from the combustion chamber 8 to the exhaust port 10. A head cover 14 that covers the valve mechanism 13 and the like is provided above the engine block 2.

  An intake passage 15 is connected to the intake port 9. An air cleaner 16 is provided at an inlet of the intake passage 15. An electric electronic throttle device 18 including a throttle valve 17 and a surge tank 19 are provided in the intake passage 15. The intake passage 15 downstream of the electronic throttle device 18 includes a well-known intake manifold 31 including a surge tank 19. The electronic throttle device 18 is configured to open and close the throttle valve 17 by a motor (not shown) in conjunction with the operation of an accelerator pedal (not shown) provided in the driver's seat. The throttle valve 17 corresponds to an example of the intake air amount adjusting means of the present invention. The surge tank 19 has a function of suppressing pulsation of intake air flowing through the intake passage 15. The air purified by the air cleaner 16 is sucked into each combustion chamber 8 through the intake passage 15, the electronic throttle device 18, and the intake port 9. The amount of intake air (the amount of intake air) is adjusted according to the opening of the throttle valve 17. The engine block 2 is provided with an injector 20 for injecting and supplying fuel to each of the combustion chambers 8. Fuel is supplied to the injector 20 from a fuel tank via a fuel pump or the like. The fuel injected from each injector 20 into each combustion chamber 8 forms an air-fuel mixture with the intake air. An ignition plug 21 for igniting the air-fuel mixture in each combustion chamber 8 is provided above the engine block 2. The ignition plug 21 is operated by the high voltage applied by the igniter 22. The injector 20 corresponds to an example of a fuel supply unit of the present invention.

  The exhaust port 10 is connected to an exhaust passage 23 including an exhaust manifold. Exhaust gas generated in each combustion chamber 8 after combustion is discharged to the outside through the exhaust port 10 and the exhaust passage 23.

  In the gasoline engine system of this embodiment, the blow-by gas generated in each combustion chamber 8 flows to the intake passage 15 (intake manifold 31) downstream of the electronic throttle device 18 (throttle valve 17) and is returned to the engine 1. (Hereinafter referred to as “BGV device”). This device includes a blow-by gas storage unit for storing blow-by gas generated in the engine 1. The blow-by gas storage unit includes a crankcase 4 and a head cover 14. The crankcase 4 and the head cover 14 communicate with each other via a communication passage 2 a provided in the engine block 2. An oil separator 24 is provided in the crankcase 4. The oil separator 24 has a function of separating and capturing oil such as lubricating oil mixed in the blow-by gas from the blow-by gas inside the crankcase 4. Between the oil separator 24 and the intake passage 15 (intake manifold 31) downstream of the throttle valve 17, the blow-by gas accumulated in the crankcase 4 flows to the intake passage 15 downstream of the throttle valve 17 to the engine 1. A blow-by gas returning passage (hereinafter, referred to as “BGV passage”) 26 for returning is provided. The BGV passage 26 is configured by a pipe such as a hose. In the BGV passage 26, a PCV valve 27 for adjusting the flow rate of blow-by gas in the passage 26 is provided. Here, the PCV valve 27 is a well-known motorized valve configured to be variable in opening, and corresponds to an example of the gas flow rate adjusting means of the present invention. Between the intake passage 15 upstream of the throttle valve 17 and the head cover 14, a part of the air flowing through the intake passage 15 is introduced into the head cover 14 in order to scavenge blow-by gas in the head cover 14 and the crankcase 4. A fresh air introduction passage 28 for introducing as fresh air is provided. Fresh air introduced into the head cover 14 is guided into the crankcase 4 via the communication passage 2a. The fresh air introduction passage 28 is provided with an on-off valve 29 for opening and closing the passage 28. Here, the open / close valve 29 is a well-known motorized valve configured to be able to open and close the valve, and is directly attached (directly attached) to the intake passage 15 without using a pipe or the like. The on-off valve 29 corresponds to an example of the on-off means of the present invention. Here, the crankcase 4, the head cover 14, the BGV passage 26, and the fresh air introduction passage 28 communicate with each other to form one blow-by gas reduction system (hereinafter, referred to as "BGV system").

  This gasoline engine system further includes an electronic control unit (ECU) 50. The air cleaner 16 is provided with an air flow meter 51 for detecting an intake air amount Ga flowing through the intake passage 15. The air flow meter 51 corresponds to an example of the intake air amount detecting means of the present invention. The electronic throttle device 18 is provided with a throttle sensor 52 for detecting the opening degree (throttle opening degree) TA of the throttle valve 17. The surge tank 19 is provided with an intake pressure sensor 53 for detecting an intake pressure PM in the intake passage 15. The engine block 2 is provided with a rotation speed sensor 54 for detecting the rotation angle (crank angle) of the crankshaft 6 as the engine rotation speed NE. The engine block 2 is provided with a water temperature sensor 55 for detecting a temperature (cooling water temperature) THW of cooling water flowing inside the engine block 2. Further, the engine block 2 is provided with a BGV pressure sensor 56 for detecting the pressure in the communication passage 2a as a BGV system pressure (BGV pressure) PV. An oxygen sensor 57 for detecting the oxygen concentration Ox in the exhaust gas is provided in the exhaust passage 23. These various sensors 51 to 57 correspond to an example of an operating state detecting means for detecting the operating state of the engine 1. The ECU 50 controls the air-fuel ratio based on the intake air amount Ga, the throttle opening degree TA, the intake pressure PM, the engine rotation speed NE, the cooling water temperature THW, the BGV pressure PV, and the oxygen concentration Ox detected by the various sensors 51 to 57. Including fuel injection control, ignition timing control, BGV control, and the like.

  Here, in the fuel injection control, the ECU 50 controls each injector 20 according to the operating state of the engine 1 and controls the amount of fuel injection supplied to the engine 1. The engine 1 receives the supply of the fuel and generates a driving force. Further, when the engine 1 is decelerated, the ECU 50 stops the fuel injection from the injector 20 and shuts off the supply of fuel to the engine 1 (fuel cut) under a predetermined condition. In the ignition timing control, the ECU 50 controls the ignition plug 21 by operating the igniter 22 according to the operating state of the engine 1. In the BGV control, the ECU 50 controls the PCV valve 27 according to the operating state of the engine 1.

  This gasoline engine system further includes an abnormality diagnosis device that diagnoses an abnormality of the BGV device. This abnormality diagnosis device includes pressure detection means for detecting the pressure in the BGV system, and abnormality diagnosis means for diagnosing an abnormality in the BGV system. The BGV pressure sensor 56 corresponds to an example of the pressure detecting means of the present invention. The ECU 50 corresponds to an example of the abnormality diagnosis means of the present invention.

  Here, as an abnormality of the BGV system, disconnection of a pipe (a hose or the like) constituting the BGV passage 26 and the fresh air introduction passage 28 and a hole in the pipe (hereinafter, simply referred to as “hole”) may be assumed. it can. The ECU 50 executes the following abnormality diagnosis control to diagnose this abnormality. That is, the ECU 50 closes the on-off valve 29 to start abnormality diagnosis when the deceleration fuel of the engine 1 is cut. Thereby, the fresh air introduction passage 28 is shut off, and the intake negative pressure generated in the intake passage 15 downstream of the throttle valve 17 is introduced into the BGV system, and the inside of the system is made negative pressure. At this time, the ECU 5 diagnoses a BGV system hole abnormality based on the BGV pressure PV detected by the BGV pressure sensor 56. Here, when the drop in the BGV pressure PV becomes relatively large, the ECU 50 can determine that there is no hole. On the other hand, when the drop in the BGV pressure PV is relatively small, it can be determined that there is a hole. When terminating the abnormality diagnosis, the ECU 50 opens the on-off valve 29. Thus, the fresh air introduction into the fresh air introduction passage 28 is restarted.

  Next, the air-fuel ratio control executed when the ECU 50 executes the abnormality diagnosis of the BGV device will be described. FIG. 2 is a flowchart showing the details of the air-fuel ratio control.

  When the process proceeds to this routine, in step 100, the ECU 50 takes in the intake air amount Ga based on the detection value of the air flow meter 51.

  Next, in step 110, the ECU 50 determines whether or not the PCV influence flag XPCVR is “0”. The flag XPCVR is set to “1” when the effect of PCV fuel vaporization (blow-by gas) is confirmed, and is set to “0” when the effect is not confirmed. The ECU 50 shifts the processing to step 120 when this determination result is affirmative, and shifts the processing to step 400 when this determination result is negative.

  In step 400, the ECU 50 stops the abnormality diagnosis of the BGV device because the influence of the PCV fuel vaporization is confirmed (the hole opening cannot be detected), and shifts the processing to step 410.

  In step 410, the ECU 50 sets the intake air amount Ga taken in step 100 as the final intake air amount GA, and shifts the processing to step 230.

  On the other hand, in step 120, the ECU 50 determines whether or not the PCV no effect flag XPCVS is “0”. This flag XPCVS is set to “1” when it is confirmed that there is no influence of PCV fuel vaporization, and is set to “0” when it is not confirmed that there is no influence. The ECU 50 shifts the processing to step 130 when the determination result is affirmative, and shifts the processing to step 250 when the determination result is negative.

  In step 130, the ECU 50 takes in the air-fuel ratio λ and stores it as the first air-fuel ratio AF1. Here, the ECU 50 can calculate the air-fuel ratio λ based on the detection value of the oxygen sensor 57.

  Next, in step 140, the ECU 50 executes the PCV flow rate increase. That is, the ECU 50 controls the PCV valve 27 to increase the flow rate of the blow-by gas flowing through the PCV valve 27.

  Next, in step 150, the ECU 50 determines whether a predetermined time T1 has elapsed. Here, for example, “0.5 seconds” can be applied as the predetermined time T1. The ECU 50 returns the process to step 140 when this determination result is negative, and shifts the process to step 160 when this determination result is positive.

  In step 160, the ECU 50 takes in the air-fuel ratio λ again and stores it as the second air-fuel ratio AF2.

  Next, in step 170, the ECU 50 stops increasing the PCV flow rate and returns to the original flow rate. That is, the ECU 50 stops increasing the flow rate of the blow-by gas flowing through the PCV valve 27 by controlling the PCV valve 27.

  Next, in step 180, the ECU 50 sets the intake amount Ga taken in in step 100 as the final intake amount GA.

  Next, at step 190, the ECU 50 calculates the air-fuel ratio change ΔAF by subtracting the second air-fuel ratio AF2 from the first air-fuel ratio AF1. This change ΔAF indicates the influence of PCV fuel vaporization (blow-by gas).

  Next, in step 200, the ECU 50 determines whether or not the air-fuel ratio change ΔAF is smaller than the reference value A1. The ECU 50 shifts the processing to step 210 when this determination result is affirmative, and shifts the processing to step 220 when this determination result is negative.

  In step 210, the ECU 50 sets the PCV non-effect flag XPCVS to "1", assuming that it is confirmed that there is no influence of the blow-by gas.

  On the other hand, in step 220, the ECU 50 sets the PCV influence flag XPCVR to “1”, assuming that the influence of the blow-by gas has been confirmed.

  Then, after shifting from step 210 or step 220, in step 230, the ECU 50 calculates the fuel injection amount TAU according to the final intake amount GA. In this embodiment, the fuel injection amount TAU corresponds to an example of the control amount of the present invention. The ECU 50 also calculates the fuel injection amount TAU in the same manner as described above when the process proceeds from step 410 to step 230, or when the process proceeds from step 300, step 350, or step 390 described below to step 230.

  Thereafter, at step 240, the ECU 50 controls the air-fuel ratio of the engine 1 by controlling the injector 20 based on the calculated fuel injection amount TAU.

  On the other hand, after shifting from step 120 to step 250, the ECU 50 determines whether or not the abnormality diagnosis condition is satisfied. The diagnosis condition may include that the engine 1 is in a deceleration fuel cut state. The ECU 50 shifts the processing to step 260 when this determination result is affirmative, and shifts the processing to step 410 when this determination result is negative.

  In step 260, the ECU 50 determines whether or not the diagnosis completion flag XPCVO is “0”. This flag XPCVO is set to “1” when the abnormality diagnosis is completed, and is set to “0” when the abnormality diagnosis is not completed. The ECU 50 shifts the processing to step 270 when this determination result is affirmative, and shifts the processing to step 310 when this determination result is negative.

At step 270, ECU 50 may be closed-off valve 29. Next, in step 280, the ECU 50 calculates the corrected final intake air amount GA by adding a predetermined correction value α to the intake air amount Ga taken in in step 100.

  Next, in step 290, the ECU 50 proceeds to step 300 after waiting for the diagnosis of the abnormality to be completed.

  In step 300, the ECU 50 sets the diagnosis completion flag XPCVO to “1”, and shifts the processing to step 230.

  On the other hand, after the process proceeds from step 260 to step 310, the ECU 50 determines whether or not the correction completion flag Xβ is “0”. The flag Xβ is set to “1” when the correction of the intake air amount Ga is completed, and is set to “0” when the correction is not completed. The ECU 50 shifts the processing to step 320 when this determination result is affirmative, and shifts the processing to step 360 when this determination result is negative.

  In step 320, the ECU 50 takes in the BGV system initial BGV pressure PVs. Next, in step 330, the ECU 50 obtains a correction value kβ corresponding to the initial BGV pressure PVs. The ECU 50 can determine the correction value kβ corresponding to the initial BGV pressure PVs by referring to a predetermined correction value map as shown in FIG. 3, for example. In this correction value map, the correction value kβ (vertical axis) according to the time TAR (horizontal axis) after the return from the abnormality diagnosis is different from the initial BGV pressure PVs (for example, −16 kPa, −12 kPa, −8 kPa, −4 kPa). ). The correction value kβ temporarily increases to a peak immediately after returning from the abnormality diagnosis, and then decreases in a curve as the post-recovery time TAR elapses.

Next, at step 340, ECU 50 will open the opening and closing valve 29. Next, in step 350, the ECU 50 sets the correction completion flag Xβ to “1”, and shifts the processing to step 230.

  On the other hand, the process proceeds from step 310 and in step 360, the ECU 50 determines whether or not the return correction completion flag XPCVA is “0”. The flag XPCVA is set to “1” when the correction of the intake air amount Ga is completed at the time of return from the abnormality diagnosis, and is set to “0” when the correction is not completed. The ECU 50 shifts the processing to step 370 when this determination result is affirmative, and shifts the processing to step 410 when this determination result is negative.

  In step 370, the ECU 50 calculates the corrected final intake air amount GA by subtracting the correction value kβ calculated in step 330 from the intake air amount Ga acquired in step 100.

Next, in step 380, the ECU 50 determines whether or not the correction value kβ is equal to or greater than “0”. The ECU 50 returns the process to step 370 if this determination is negative , and shifts the process to step 390 if this determination is positive .

  Then, in step 390, after setting the return correction completion flag XPCVA to “1”, the ECU 50 shifts the processing to step 230.

  FIG. 4 is a time chart showing changes in various parameters when the above-described air-fuel ratio control is executed. FIG. 4 shows (a) opening and closing of the on-off valve 29, (b) PCV flow rate (blow-by gas flow rate flowing through the PCV valve 27), (c) BGV pressure PV (pressure in the BGV system), and (d) intake air amount Ga ( (E) shows the amount of intake air detected by the air flow meter 51) and (e) the air-fuel ratio λ of the engine 1. FIG. 5 is a schematic configuration diagram showing the flow of intake air and blow-by gas at the start of abnormality diagnosis of a BGV device in a gasoline engine system. FIG. 6 is a schematic configuration diagram showing the flow of intake air and blow-by gas at the end of abnormality diagnosis of a BGV device in a gasoline engine system.

  In FIG. 4, when the on-off valve 29 is opened at time t0, the PCV flow rate shows a certain value, the BGV pressure PV approaches the atmospheric pressure, the intake air amount Ga shows a certain value, and the air-fuel ratio λ It has become a steak.

  Thereafter, when the PCV valve 27 is controlled and the PCV flow rate is increased between the time t1 and the time t2 while the on-off valve 29 is opened, the BGV pressure PV slightly decreases, and the intake air amount Ga Slightly increases, and the air-fuel ratio λ changes to the lean side. At this time, if the amount of fuel component mixed into the engine oil in the crankcase 4 is large, the air-fuel ratio λ may shift to the rich side. Accordingly, in this embodiment, the PCV flow rate is increased by controlling the PCV valve 27, and the air-fuel ratio change ΔAF is obtained by changing the air-fuel ratio λ, and the effect of PCV fuel vaporization (blow-by gas) is determined based on the value. I am to judge. For example, when it is determined that the influence of the blow-by gas is large, the influence on the air-fuel ratio λ is further added, so that the abnormality diagnosis (hole hole abnormality diagnosis) of the BGV device is stopped.

  Thereafter, in FIG. 4, when the PCV flow rate is fixed, at time t3, when the on-off valve 29 is closed to start abnormality diagnosis, the BGV pressure PV starts to decrease. At this time, as shown in FIG. 5, fresh air is not introduced into the fresh air introduction passage 28, but the intake air (indicated by a white arrow) detected by the air flow meter 51 passes through the throttle valve 17. Flows to engine 1. Further, as shown in FIG. 5, blow-by gas (indicated by black arrows) not detected by the air flow meter 51 flows through the BGV passage 26 to the intake passage 15 and is sucked into the engine 1. Therefore, the intake air amount Ga detected by the air flow meter 51 is smaller than the actual intake air amount sucked into the engine 1 by the amount of the blow-by gas flow. As a result, the fuel injection amount TAU calculated based on the intake air amount Ga becomes smaller than a required value (a value necessary to make the air-fuel ratio λ stoichiometric), and the air-fuel ratio λ of the engine 1 shifts to the lean side. become.

  In FIG. 4, the decrease in the BGV pressure PV continues until the on-off valve 29 opens at time t4, that is, until the abnormality diagnosis ends (when returning to normal BGV control). Between t4 and time t5, the BGV pressure PV suddenly returns to a value close to the original atmospheric pressure. This is because, when the valve is opened, a part of the intake air flowing through the intake passage 15 flows to the fresh air introduction passage 28 at a stretch, as indicated by a white arrow in FIG. At this time, the intake air amount Ga detected by the air flow meter 51 increases in a pulsed manner by the amount flowing into the crankcase 4 and the head cover 14 through the fresh air introduction passage 28, and the increased amount b1 is actually increased by the engine. It is not the amount of intake air to be sucked into 1. As a result, the fuel injection amount TAU calculated based on the intake air amount Ga becomes larger than a required value (a value necessary for making the air-fuel ratio λ stoichiometric), and the air-fuel ratio λ of the engine 1 shifts to the rich side. Will be.

Therefore, in this embodiment, in FIG. 4D, the decrease a1 in the intake air amount Ga from time t3 to time t4 and the increase b1 in the intake air amount Ga from time t4 to time t5 are respectively corrected. The air-fuel ratio of the engine 1 is stoichiometrically controlled by correcting the value α and the correction value kβ to obtain the final intake amount GA, and calculating the fuel injection amount TAU based on the final intake amount GA. . That is, when starting the abnormality diagnosis of the BGV device, the ECU 50 corrects the fuel injection amount TAU by correcting the intake air amount Ga to the final intake air amount GA so that the air-fuel ratio likely to lean becomes the target value. When the abnormality diagnosis of the BGV device is completed, the fuel injection amount TAU is corrected by correcting the intake air amount Ga to the final intake air amount GA so that the air-fuel ratio likely to become rich becomes the target value. I have.

  According to the engine system of this embodiment described above, the abnormality of the BGV device is diagnosed when the deceleration fuel of the engine 1 is cut. Here, during the deceleration fuel cut, no torque is generated in the engine 1, the throttle valve 17 is closed, and the intake air passing through the throttle valve 17 is kept constant in the sonic state. Therefore, the ECU 50 closes the fresh air introduction passage 28 by the on-off valve 29 during the operation of the engine (during deceleration fuel cut), and at that time, starts the abnormality diagnosis of the BGV system based on the detection value of the BGV pressure sensor 56. When the abnormality diagnosis is completed, the on-off valve 29 opens the fresh air introduction passage 28. Therefore, when diagnosing an abnormality in the BGV system, the abnormality diagnosis is performed based on a stable pressure (BGV pressure PV) in the BGV system. For this reason, accurate abnormality diagnosis can be performed for the BGV system.

Further, according to the configuration of this embodiment, the ECU 50 calculates the fuel injection amount TAU based on the detection value of the air flow meter 51 in order to adjust the air-fuel ratio of the engine 1 to a predetermined target value, and detects an abnormality in the BGV system. When the diagnosis is started, the calculated fuel injection amount TAU is corrected so that the air-fuel ratio likely to lean becomes the target value . Specifically, the calculated fuel injection amount TAU is corrected by correcting the intake air amount Ga detected by the air flow meter 51. Therefore, when the fresh air introduction passage 28 is closed by the on-off valve 29 to start the abnormality diagnosis, undetected air of the BGV system (mainly in the crankcase 4 and the head cover 14) is sucked into the engine 1 and Even when the air-fuel ratio of the air-fuel ratio becomes lean, the air-fuel ratio is corrected so as to become the target value , and the air-fuel ratio is suppressed. Therefore, abnormality diagnosis of the BGV device can be started without affecting the air-fuel ratio control of the engine 1, that is, without making the air-fuel ratio lean.

Further, according to the configuration of this embodiment, the ECU 50 calculates the fuel injection amount TAU based on the detection value of the air flow meter 51 in order to adjust the air-fuel ratio of the engine 1 to a predetermined target value, and detects an abnormality in the BGV system. When ending the diagnosis, the calculated fuel injection amount TAU is corrected so that the air-fuel ratio likely to be enriched becomes the target value . Specifically, the calculated fuel injection amount TAU is corrected by correcting the intake air amount Ga detected by the air flow meter 51. Therefore, when the fresh air introduction passage 28 is opened by the on-off valve 29 to end the abnormality diagnosis, a part of the detected intake air amount Ga passes through the fresh air introduction passage 28 to the BGV system (mainly in the crankcase 4 or the head cover). 14), the air-fuel ratio of the engine 1 is likely to be enriched, so that the air-fuel ratio is corrected to the target value, and the enrichment is suppressed. Therefore, the abnormality diagnosis of the BGV device can be completed without affecting the air-fuel ratio control of the engine 1, that is, without enriching the air-fuel ratio.

  According to this embodiment, since the on-off valve 29 is directly attached to the intake passage 15, there is no piping between the intake passage 15 and the on-off valve 29, and a portion for diagnosing a perforated abnormality is omitted by the amount of the piping. You. Therefore, the diagnosis of the perforation abnormality in the fresh air introduction passage 28 can be simplified by that much.

  Note that the present invention is not limited to the above-described embodiment, and may be implemented by appropriately changing a part of the configuration without departing from the spirit of the invention.

  (1) In the above embodiment, in order to correct the fuel injection amount TAU, which is a control amount, the intake air amount Ga detected by the air flow meter 51 is corrected. On the other hand, the fuel injection amount may be corrected by calculating the basic fuel injection amount based on the intake air amount detected by the air flow meter, and correcting the basic fuel injection amount.

  (2) In the above embodiment, the PCV valve 27 as the gas flow rate adjusting means is constituted by an electric valve, but may be constituted by a PCV valve which operates in response to pressure instead of an electric valve.

  (3) In the above embodiment, the open / close valve 29 is directly attached to the intake passage 15, but the open / close valve may be connected to the intake passage 15 via a pipe such as a pipe.

  INDUSTRIAL APPLICATION This invention can be utilized for the BGV apparatus provided in a gasoline engine etc.

1 Engine 4 Crankcase (Blow-by gas storage)
14 Head cover (blow-by gas storage unit)
15 Intake passage 17 Throttle valve (intake amount adjusting means)
20 Injector (fuel supply means)
26 BGV passage (blow-by gas return passage)
27 PCV valve (gas flow control means)
28 Fresh air introduction passage 29 Open / close valve (open / close means)
50 ECU (abnormality diagnosis means, air-fuel ratio control means)
51 air flow meter (intake air amount detection means)
56 BGV pressure sensor (pressure detection means)
Ga intake amount GA final intake amount PV BGV pressure TAU fuel injection amount (control amount)

Claims (2)

A blow-by gas reducing device for flowing blow-by gas generated by the engine to an intake passage and reducing the blow-by gas to the engine;
An abnormality diagnosis device that diagnoses an abnormality of the blow-by gas reduction device,
An engine system including an air-fuel ratio control device that controls an air-fuel ratio of the engine,
The blow-by gas reducing device includes a blow-by gas storage unit for storing blow-by gas generated in the engine, and an intake air amount adjusting unit provided in the intake passage for adjusting an intake air amount flowing through the intake passage. A blow-by gas returning passage for flowing the blow-by gas accumulated in the blow-by gas accumulating section to the intake passage downstream of the intake air amount adjusting means and returning the blow-by gas to the engine; and adjusting a blow-by gas flow rate in the blow-by gas returning passage. And a fresh air introduction for connecting a part of the air flowing through the intake passage as fresh air to the blow-by gas accumulation unit, the gas being supplied to the blower gas storage unit. A passage, and an opening / closing means for opening / closing the fresh air introduction passage; Baigasu returning passage and the fresh air introduction passage is formed is one of the blow-by gas reduction system communicates,
The abnormality diagnosis device includes a pressure detection unit for detecting a pressure in the blow-by gas reduction system, and an abnormality diagnosis unit for diagnosing an abnormality of the blow-by gas reduction system. During operation of the engine, the fresh air introduction passage is closed by the opening / closing means, and at that time abnormality diagnosis is started based on the detection value of the pressure detection means. Is configured to open the air introduction passage,
The air-fuel ratio control device includes a fuel supply unit configured to supply fuel to the engine, and an intake air amount detection unit configured to detect an amount of intake air flowing through the intake passage upstream of a connection with the fresh air introduction passage. An air-fuel ratio control unit that calculates a control amount based on a detection value of the intake air amount detection unit to adjust the air-fuel ratio to a predetermined target value, and controls the fuel supply unit based on the control amount. An engine, wherein the air-fuel ratio control means corrects the control amount so that the air-fuel ratio likely to be enriched becomes the target value when the abnormality diagnosis means ends the abnormality diagnosis. system. The air-fuel ratio control means corrects the control amount such that the air-fuel ratio that is likely to lean becomes the target value when the abnormality diagnosis device starts the abnormality diagnosis. An engine system according to claim 1.

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