JP4985610B2 - Abnormality judgment device for blow-by gas processing system - Google Patents

Description

  The present invention relates to an abnormality determination device that determines whether there is an abnormality in a blowby gas processing system.

  As a system provided in an internal combustion engine, a blow-by gas processing system that discharges and processes combustion gas (blow-by gas) leaking into a crankcase from a gap between a cylinder and a piston into an intake passage has been put into practical use.

  Such a system includes a first communication passage that communicates a portion of the intake passage of the internal combustion engine that is downstream of the throttle valve in the intake flow direction and the inside of the crankcase. There is known a PCV valve to be changed and a second communication passage that communicates a portion of the intake passage upstream of the throttle valve in the intake flow direction with the inside of the crankcase (for example, see Patent Document 1).

In this system, the blow-by gas processing is performed such that the blow-by gas in the crankcase is discharged to the intake passage through the first communication passage using the intake negative pressure and the air is introduced into the crank case through the second communication passage. Executed.
Japanese Patent Laid-Open No. 10-184336

  By the way, in the blow-by gas processing system, when the PCV valve does not operate normally or the first passage or the second passage is clogged or perforated, an appropriate amount of blow-by gas cannot be discharged to the intake passage, and the blow-by gas is discharged. There is a risk that the gas cannot be properly processed. Further, if the amount of blow-by gas discharged to the intake passage through the first passage changes unnecessarily, or if air enters through the hole opened in the first passage and is introduced into the intake passage, the air-fuel mixture becomes empty. There is a possibility that the engine operating performance may be deteriorated by changing the fuel ratio unnecessarily. Therefore, in an internal combustion engine equipped with a blow-by gas processing system, it is desired to accurately determine the presence or absence of the abnormality in order to appropriately deal with the abnormality of the system.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an abnormality determination device that can accurately determine the presence or absence of an abnormality in a blow-by gas processing system.

In the following, means for achieving the above object and its operational effects will be described.
The invention according to claim 1 changes the passage cross-sectional area of the first communication passage that communicates with the portion of the intake passage of the internal combustion engine that is downstream of the throttle valve in the intake flow direction and the inside of the crankcase. The present invention is applied to a blow-by gas processing system having a PCV valve, a portion of the intake passage upstream of the throttle valve in the intake flow direction, and a second communication passage communicating with the inside of the crankcase. In the abnormality determination device for determining, the amount of air passing through a portion upstream of the connection portion of the second communication passage in the intake passage in the intake flow direction, the opening of the throttle valve, and the throttle valve in the intake passage Estimating means for estimating the amount of gas passing through the first communication path based on the pressure at the downstream side of the intake flow direction The gist of the invention includes: a calculation unit that calculates a reference flow rate based on the pressure; and a determination unit that determines whether there is an abnormality in the blow-by gas processing system based on a comparison result between the gas amount and the reference flow rate. And

  In the blow-by gas processing system, the crankcase is connected to the crankcase through the first communication passage by utilizing the difference between the pressure in the intake passage downstream of the throttle valve in the intake flow direction (intake pressure) and the upstream pressure in the intake flow direction. The blow-by gas inside is discharged into the intake passage and air is introduced into the crankcase through the second communication passage. That is, a flow path of gas that flows around the throttle valve (intake passage → second communication passage → crankcase → first communication passage “PCV valve” → intake passage) is formed.

  As such, the amount of gas that flows around the throttle valve is equal to the amount of gas passing through the first passage (PCV flow rate). The PCV flow rate is obtained by calculating the amount of air passing through the throttle valve (throttle passage flow rate) from the amount of air passing through the portion in the intake flow direction upstream of the connection portion of the second communication passage in the intake passage (passage intake amount). This is a subtracted value, and the throttle passage flow rate can be obtained based on the throttle valve opening and the intake pressure. Therefore, it can be said that the PCV flow rate can be accurately estimated based on the passage intake amount, the throttle valve opening, and the intake pressure.

  Further, since the gas (including blow-by gas) is discharged from the crankcase into the intake passage using the intake pressure, the PCV when no abnormality occurs in the blow-by gas processing system based on the intake pressure. It is possible to obtain a value corresponding to the flow rate (the reference flow rate).

  According to the above configuration, it is determined that there is an abnormality when the estimated PCV flow rate deviates from the reference flow rate as described above, and it is determined that there is no abnormality when the PCV flow rate and the reference flow rate do not deviate. As described above, by comparing the PCV flow rate with the reference flow rate, it is possible to accurately determine whether there is an abnormality in the blow-by gas processing system.

  According to a second aspect of the present invention, in the abnormality determination device for the blow-by gas processing system according to the first aspect, the estimation of the gas amount by the estimation unit and the calculation of the reference flow rate by the calculation unit are performed by an internal combustion engine. The gist is to execute it under the condition that a predetermined condition for determining that the change per unit time of the operating state is small is satisfied.

  According to the above configuration, the parameters used for determining whether there is an abnormality in the blow-by gas processing system (the passage intake amount, the throttle valve opening, the intake pressure) have a small change per unit time, that is, the above determination. Thus, the detection can be performed in a situation in which the disturbance is removed, and the determination can be performed with high accuracy.

  According to a third aspect of the present invention, in the abnormality determination device for the blow-by gas processing system according to the second aspect, the predetermined condition is that a change per unit time in the pressure in the downstream portion in the intake flow direction is small. The gist is to include the above conditions.

  When the PCV valve is fixed at a predetermined opening, if the change in the operating state of the internal combustion engine is small, the change in the intake pressure or the PCV flow rate becomes very small. Thus, when changes in intake pressure and PCV flow rate are very small, the PCV flow rate can be accurately estimated and the reference flow rate can be accurately calculated. Therefore, the blow-by gas processing system is compared with the PCV flow rate and the reference flow rate. It is possible to accurately determine whether or not there is an abnormality.

According to the above configuration, it is possible to execute abnormality determination in such a situation, and it is possible to accurately determine whether there is an abnormality in the blow-by gas processing system.
According to a fourth aspect of the present invention, in the abnormality determination device for a blow-by gas processing system according to any one of the first to third aspects, the internal combustion engine sends fuel vapor generated in a fuel tank to the intake passage. The gist of the present invention is that a fuel vapor processing system for discharging and processing is provided.

  When the gas in the crankcase (including blow-by gas) is discharged to the intake passage through the first communication passage, the oxygen concentration in the intake air and the oxygen concentration in the exhaust gas change accordingly. By using it, it is possible to determine whether there is an abnormality in the blow-by gas processing system. However, in an internal combustion engine provided with a fuel vapor processing system, when the fuel vapor is discharged into the intake passage, the oxygen concentration in the intake air and the oxygen concentration in the exhaust gas change accordingly. If abnormality determination based on the oxygen concentration of intake air or the oxygen concentration of exhaust gas is executed, the determination accuracy is significantly reduced. In order to avoid such a decrease in determination accuracy, it may be possible to execute the abnormality determination only when the discharge of the fuel vapor to the intake passage is stopped. In this case, however, an abnormality determination execution opportunity or the fuel vapor to the intake passage is considered. There is a risk that it will not be possible to secure a sufficient amount of discharge.

  In this regard, according to the above configuration, since the abnormality determination based on the PCV flow rate is executed, the blow-by gas processing system is used even when the fuel vapor is discharged into the intake passage by the fuel vapor processing system. It is possible to accurately determine whether or not there is an abnormality. For this reason, it is possible to ensure both an abnormality determination execution opportunity and a fuel vapor discharge amount into the intake passage.

  The estimating means, as in claim 5, obtains the amount of air passing through the throttle valve (the throttle passing flow rate) based on the throttle valve opening and the pressure (the intake pressure), and It is possible to adopt a configuration in which the estimated value of the gas amount is obtained by subtracting the obtained amount of air from the amount of air passing through the upstream portion in the intake flow direction (the passage intake amount).

Hereinafter, an embodiment embodying an abnormality determination device for a blow-by gas processing system according to the present invention will be described.
FIG. 1 shows a schematic configuration of an internal combustion engine and its peripheral devices to which the abnormality determination device according to the present embodiment is applied.

  As shown in FIG. 1, a throttle mechanism 12 is provided in the intake passage 11 of the internal combustion engine 10. The throttle mechanism 12 includes a throttle valve 13 and a throttle motor 14. The opening of the throttle valve 13 (throttle opening TA) is adjusted through the drive control (throttle control) of the throttle motor 14, thereby adjusting the amount of air taken into the combustion chamber 15 through the intake passage 11. The The intake passage 11 is provided with a fuel injection valve 16. The fuel injection valve 16 is driven to open through its operation control (fuel injection control), thereby injecting fuel into the intake passage 11 (specifically, the intake port 11a).

  In the combustion chamber 15 of the internal combustion engine 10, an air-fuel mixture composed of intake air and injected fuel is ignited and burned. By this combustion, the piston 18 reciprocates and the crankshaft 19 rotates. The air-fuel mixture after combustion is sent out from the combustion chamber 15 to the exhaust passage 20 as exhaust.

  The internal combustion engine 10 is provided with an oil tank 21 for storing oil, and a pump 22 is provided inside the oil tank 21. The oil in the oil tank 21 is supplied to each operating part of the internal combustion engine 10 by being pumped by the pump 22. The oil after being used for lubrication of each operating part is stored in the oil tank 21 by being transferred down the inner wall of the internal combustion engine 10 or the like.

  The internal combustion engine 10 is provided with a fuel vapor processing system 30. The fuel vapor processing system 30 includes a canister 31 that adsorbs fuel vapor generated in the fuel tank 23, a vapor passage 32 that communicates the fuel tank 23 and the canister 31, and a throttle valve 13 in the intake passage 11 of the internal combustion engine 10. A purge passage 33 that communicates with a portion on the downstream side in the intake flow direction (hereinafter simply referred to as downstream side) and the canister 31 is provided.

  The fuel vapor generated in the fuel tank 23 is sent to the canister 31 through the vapor passage 32. The canister 31 includes an adsorbent therein, and temporarily stores fuel vapor (vapor phase fuel) from the fuel tank 23 by adsorbing the adsorbent while condensing it into liquid phase fuel. The canister 31 has a configuration that allows the fuel adsorbed on the adsorbent to be detached again.

  A purge control 34 is provided in the middle of the purge passage 33 that connects the canister 31 and the intake passage 11, and an electromagnetic control valve is employed as the purge control 34. The canister 31 is connected to an air introduction passage 35 for introducing air into the canister 31.

  The fuel vapor processing system 30 functions as follows. That is, first, fuel vapor generated in the fuel tank 23 is sent to the canister 31 through the vapor passage 32 and is adsorbed by the adsorbent of the canister 31. When the purge control 34 is opened through the operation control (purge control) of the purge control 34 based on the operating state of the internal combustion engine 10, the pressure downstream of the throttle valve 13 in the intake passage 11 (intake pressure “<large”). Atmospheric pressure ”) is supplied to the canister 31 via the purge passage 33, while atmospheric pressure is introduced to the canister 31 via the atmosphere introduction passage 35. As a result, the fuel adsorbed by the adsorbent of the canister 31 is separated as fuel vapor and discharged into the intake passage 11.

  The internal combustion engine 10 is provided with a fresh air introduction passage 41 that communicates a portion of the intake passage 11 upstream of the throttle valve 13 in the intake flow direction (hereinafter simply upstream) with the inside of the crankcase 24. The internal combustion engine 10 is also provided with a gas discharge passage 42 that communicates a portion of the intake passage 11 downstream of the throttle valve 13 with the inside of the crankcase 24. Further, a PCV valve 43 is provided in the gas discharge passage 42. An electromagnetic control valve is employed as the PCV valve 43, and the passage sectional area of the gas discharge passage 42 can be changed through opening control of the PCV valve 43. In the present embodiment, the fresh air introduction passage 41, the gas discharge passage 42, and the PCV valve 43 constitute a blow-by gas processing system 40 that discharges and processes the blow-by gas in the crankcase 24 into the intake passage 11. . The blow-by gas is gas (including fuel) that leaks from the combustion chamber 15 into the crankcase 24 through the gap between the piston ring 25 and the cylinder inner wall surface 26 of the internal combustion engine 10 during the compression stroke and expansion stroke of the internal combustion engine 10. That is.

  In this blow-by gas processing system 40, basically, the gas (including blow-by gas) in the crankcase 24 is sucked through the gas discharge passage 42 by utilizing the difference between the intake pressure and the pressure in the crankcase 24. It is discharged into the passage 11. Further, by utilizing the difference between the pressure in the crankcase 24 that decreases as the gas is discharged into the intake passage 11 and the pressure on the upstream side of the throttle valve 13 in the intake passage 11, fresh air in the intake passage 11 is used. Is introduced into the crankcase 24 through the fresh air introduction passage 41. Further, the amount of gas discharged to the intake passage 11 of the internal combustion engine 10 is adjusted through the opening degree control (PCV control) of the PCV valve 43.

<Electronic control unit>
The internal combustion engine 10 includes an electronic control unit 27 configured to include a microcomputer, for example. The electronic control unit 27 captures detection signals from various sensors for detecting the operating state of the internal combustion engine 10.

  As various sensors, for example, a crank sensor for detecting the rotational speed of the crankshaft 19 (engine rotational speed NE), an accelerator sensor for detecting the amount of depression of an accelerator pedal (not shown) (accelerator depression amount ACC), A throttle sensor for detecting the opening of the throttle valve 13 (throttle opening TA) is provided. Further, an air flow meter for detecting the amount of air flowing upstream from the connection portion of the intake passage 11 with the fresh air introduction passage 41 (passage intake air amount GA) and the temperature of the engine cooling water (cooling water temperature THW) are detected. There are also provided a temperature sensor for detecting the pressure, a pressure sensor for detecting a pressure (intake pressure PM) at a portion downstream of the throttle valve 13 in the intake passage 11 and the like.

  The electronic control unit 27 performs various calculations based on detection signals from various sensors, and executes various controls such as throttle control, fuel injection control, purge control, and PCV control based on the calculation results.

  In the present embodiment, PCV control is executed as follows. That is, first, the required value GBT for the amount of gas (PCV flow rate) passing through the gas discharge passage 42 is calculated based on the passage intake amount MA and the engine rotational speed NE. Thereafter, based on the required value GBT, the throttle opening degree TA, and the engine speed NE, it corresponds to the opening degree (PCV opening degree) of the PCV valve 43 that can make the actual PCV flow rate coincide with the required value GBT. A value to be calculated is calculated, and the same value is set as a control target value (target PCV opening) of the PCV opening. Then, the PCV control is executed so that the target PCV opening matches the actual PCV opening.

The required value GBT of the PCV flow rate is calculated based on the following idea.
FIG. 2 shows the relationship between the operating state of the internal combustion engine 10 and the required value GBT.
A curve GBT1 to a curve GBT5 shown in FIG. 2 indicate that the required value GBT of the PCV flow rate is the same, and the relationship between the magnitudes of the required values GBT between these curves is expressed by a relation expression “GBT1> GBT2 >GBT3>GBT4> GBT5 ”. Further, between one curve and another curve having different PCV flow rate required values GBT (for example, between the curve GBT1 and the curve GBT2), the PCV flow rate required value GBT is a curve (curve having a large required value GBT). It is set in such a manner that it gradually decreases from GBT1) toward a curve (curve GBT2) having a smaller required value GBT. Instead of this setting mode, for example, the required value GBT may be unified with one of these curves between one curve and another curve having the same or different PCV flow rate required values GBT. it can.

  As shown in FIG. 2, when the engine load (in this embodiment, passage intake air amount GA / engine rotational speed NE) is in the middle load region, the required value GBT is set to the largest value, and the engine load is from this region. The required value GBT gradually decreases as the shift to the high load region is performed, and is set to be minimum in the region on the highest load side. Further, as the engine load shifts from the middle load region to the low load region, the required value GBT gradually decreases, and the required value GBT is set smaller in the high rotation low load region in the low load region than in the other low load regions. The

  Here, when an abnormality occurs in the blow-by gas processing system 40, it is necessary to appropriately cope with the abnormality, for example, by turning on a warning light to prompt inspection and repair. In view of this point, in the present embodiment, the following processing (abnormality determination processing) is performed in order to accurately determine whether there is an abnormality in the blowby gas processing system 40.

Hereinafter, an execution mode of the abnormality determination process will be described.
FIG. 3 is a flowchart showing an execution procedure of the abnormality determination process, and a series of processes shown in this flowchart is executed by the electronic control unit 27 as an interrupt process for each predetermined cycle.

As shown in FIG. 3, in this process, it is first determined whether or not a predetermined condition is satisfied (step S101). Here, it is determined that the predetermined condition is satisfied when all of the following [Condition A] to [Condition C] are satisfied.
[Condition A] The internal combustion engine 10 has been warmed up (specifically, the coolant temperature THW is equal to or higher than a predetermined temperature “for example, 80 ° C.”).
[Condition b] A state in which the amount of change per unit time of the throttle opening degree TA (for example, the control cycle “several tens of milliseconds” of this process) is smaller than a predetermined value is continued for a predetermined period (for example, several seconds).
[Condition C] The amount of change per unit time (for example, the control cycle “several tens of milliseconds”) of the intake pressure PM is smaller than a predetermined value.

  If the predetermined condition is not satisfied (step S101: NO), the warm-up of the internal combustion engine 10 is not completed or the change per unit time of the operation state of the internal combustion engine 10 is relatively large, so Assuming that the abnormality of the gas processing system 40 cannot be accurately determined, the present process is temporarily terminated without executing the following process.

  On the other hand, if the predetermined condition is satisfied (step S101: YES), since the change per unit time of the operating state of the internal combustion engine 10 is very small and stable, the blow-by gas processing system 40 The following processing (steps S102 to S108) is executed on the assumption that the abnormality can be accurately determined.

  Specifically, first, the amount of air passing through the throttle valve 13 (throttle passage flow rate MT) is obtained based on the throttle opening degree TA and the intake pressure PM (step S102).

  In the present embodiment, a physical model that models the structure around the throttle valve 13 in the intake passage 11 is constructed, and the throttle passage flow rate MT is obtained through this physical model. More specifically, a model equation having the passage intake air amount MA and the throttle opening degree TA as variables is determined in advance and stored in the electronic control unit 27, and the throttle passage flow rate MT is obtained through the model equation.

  Incidentally, the model formula is determined based on a general “throttle formula”, experimental results, and the like, and a larger amount is calculated as the throttle opening TA as the throttle opening TA is larger. As shown in FIG. 4, the throttle passage flow rate MT decreases as the intake pressure PM decreases (specifically, the pressure ratio “the pressure PA between the upstream portion of the throttle valve 13“ ≈ atmospheric pressure ”and the intake pressure PM“ = PM / PA ”is a smaller value. As can be seen from FIG. 4, the same is applied to the region where the intake pressure PM is low (the region where the pressure ratio is small) in the entire pressure region. The change in the intake pressure PM does not affect the throttle passage flow rate MT because the flow velocity of the air passing through the throttle valve 13 exceeds the sonic velocity in the above region, and the pressure from the downstream side to the upstream side of the air flow. 4 is considered to be a phenomenon that occurs when the flow velocity of the air becomes faster than the propagation speed of the change. It shows the relationship between Le passing flow MT.

  Thereafter, a value obtained by subtracting the throttle passage flow rate MT from the passage intake air amount MA (= MA−MT) is calculated as an estimated value (estimated PCV flow rate MP) for the PCV flow rate (step S103).

  Here, in the blow-by gas processing system 40, the difference between the pressure in the portion upstream of the throttle valve 13 in the intake passage 11 and the pressure (intake pressure) in the portion downstream of the throttle valve 13 is used. Blow-by gas is discharged into the intake passage 11 through the gas discharge passage 42 and air is introduced into the crankcase 24 through the fresh air introduction passage 41. That is, a flow path of gas that flows around the throttle valve 13 (specifically, a path such as the intake passage 11 → the fresh air introduction passage 41 → the crankcase 24 → the gas discharge passage 42 “PCV valve 43” → the intake passage 11) is formed. Has been.

  As such, the amount of gas flowing around the throttle valve 13 is equal to the amount of gas passing through the gas discharge passage 42 (PCV flow rate). Therefore, the PCV flow rate is determined based on the amount of air passing through the throttle valve 13, in other words, the amount of air passing through the portion of the intake passage 11 upstream of the connection portion of the fresh air introduction passage 41 (passage intake amount MA). This amount is obtained by subtracting the amount of air passing through the valve 13 (throttle passage flow rate MT). Based on this point, in this process, the estimated PCV flow rate MP is calculated by subtracting the throttle passage flow rate MT from the passage intake air amount MA.

  In the present embodiment, by the processing in steps S102 and S103, a value corresponding to the actual PCV flow rate is accurately obtained as the estimated PCV flow rate MP based on the passage intake amount MA, the throttle opening degree TA, and the intake pressure PM. Be able to. In the present embodiment, the processes in steps S102 and S103 function as estimation means.

  After the estimated PCV flow rate MP is calculated in this way, the average value of the estimated PCV flow rate MP is calculated, and the count value of the calculation counter is incremented (step S104).

  If the count value is less than the predetermined value (step S105: NO), that is, the number of times of calculation of the estimated PCV flow rate MP after the previous blow-by gas processing system 40 abnormality determination (step S107 described later) is executed. If the predetermined number of times (for example, several times) has not been reached, this processing is temporarily terminated without executing the following processing.

  Thereafter, when this process is repeatedly executed and the count value becomes equal to or greater than the predetermined value (step S105: YES), the PCV flow rate reference value (reference flow rate) is determined based on the intake pressure PM, assuming that the calculated number has reached the predetermined number. MPb) is calculated (step S106). In the present embodiment, the process of step S106 functions as a calculation unit.

  Here, in the blow-by gas processing system 40, as described above, the discharge of gas (including blow-by gas) from the crankcase 24 to the intake passage 11 is performed using the intake pressure PM. Therefore, based on the intake pressure PM, it is possible to obtain a value (the reference flow rate MPb) corresponding to the PCV flow rate when no abnormality has occurred in the blow-by gas processing system 40.

  FIG. 5 shows the relationship between the intake pressure PM and the reference flow rate MPb. As shown in FIG. 5, the reference flow rate MPb is the largest when the intake pressure PM is a predetermined pressure P1. As the intake pressure PM becomes lower than the predetermined pressure P1, and as the intake pressure PM becomes higher than the predetermined pressure P1, a smaller amount is calculated as the reference flow rate MPb. Incidentally, in the present embodiment, since the PCV control is executed so that the relationship between the operating state of the internal combustion engine 10 and the PCV flow rate becomes the relationship shown in FIG. 2, the relationship between the intake pressure PM and the reference flow rate MPb is shown in FIG. The relationship shown in

  Thereafter, the average value of the estimated PCV flow rate MP and the reference flow rate MPb are compared, and the presence or absence of abnormality of the blow-by gas processing system 40 is determined based on the comparison result (step S107). In the present embodiment, the process of step S107 functions as a determination unit.

  Specifically, first, an absolute value of a difference between the average value of the estimated PCV flow rate MP and the reference flow rate MPb is obtained. When the absolute value is larger than the predetermined determination value, the average value of the estimated PCV flow rate MP and the reference flow rate MPb are deviated from each other, and there is a high possibility that an abnormality has occurred in the blowby gas processing system 40. A determination to this effect is made. On the other hand, when the absolute value is less than or equal to the predetermined determination value, the average value of the estimated PCV flow rate MP and the reference flow rate MPb are not deviated, and it is unlikely that an abnormality has occurred in the blow-by gas processing system 40. Then, it is determined that there is no abnormality.

  After such determination, the count value of the calculation counter is reset to “0”, and the average value of the estimated PCV flow rate MP is reset to the initial state (step S108), and this process is temporarily ended.

  By executing such an abnormality determination process, the throttle passage flow rate MT can be accurately calculated based on the passage intake air amount MA and the throttle opening degree TA, and this throttle passage flow rate MT is subtracted from the passage intake air amount MA. An estimated value of the flow rate (the estimated PCV flow rate MP) can be calculated. Further, based on the intake pressure PM, a value (the reference flow rate MPb) corresponding to the PCV flow rate when no abnormality occurs in the blow-by gas processing system 40 can be obtained. Then, by comparing the estimated PCV flow rate MP and the reference flow rate MPb, it is possible to accurately determine whether the blow-by gas processing system 40 is abnormal.

  In the abnormality determination process, the process for calculating the estimated PCV flow rate MP and the process for calculating the reference flow rate MPb satisfies a predetermined condition for determining that the change per unit time of the operating state of the internal combustion engine 10 is small. It is executed on the condition. For this reason, the parameters (specifically, the passage intake air amount GA, the throttle opening degree TA, and the intake pressure PM) used for calculating the estimated PCV flow rate MP and the reference flow rate MPb are in a state where changes per unit time are small, that is, It is possible to detect in a situation excluding the disturbance regarding the determination of the presence or absence of the abnormality. Therefore, it is possible to accurately calculate values that match the actual situation as the estimated PCV flow rate MP and the reference flow rate MPb, and to accurately determine whether there is an abnormality in the blow-by gas processing system 40.

  Here, when the change in the operating state of the internal combustion engine 10 is small when the PCV valve 43 is fixed at a predetermined opening, the change in the intake pressure PM and the PCV flow rate becomes very small. Thus, when changes in the intake pressure PM and the PCV flow rate are very small, both the value corresponding to the PCV flow rate (estimated PCV flow rate MP) and the reference flow rate MPb can be accurately calculated. By comparing the PCV flow rate MP and the reference flow rate MPb, it is possible to accurately determine whether or not the blow-by gas processing system 40 is abnormal. In this regard, in the abnormality determination process, a condition including a condition that the change per unit time of the intake pressure PM is small ([Condition C]) is set as the predetermined condition. Therefore, the presence or absence of abnormality of the blowby gas processing system 40 can be determined with high accuracy. In particular, when the PCV valve 43 is fixed at a predetermined opening, it can be determined with high accuracy and “abnormal” can be determined.

  When the gas (including blow-by gas) in the crankcase 24 is discharged to the intake passage 11 through the gas discharge passage 42, the oxygen concentration in the intake air and the oxygen concentration in the exhaust gas change accordingly. By doing so, it is possible to determine whether there is an abnormality in the blow-by gas processing system 40.

  However, in this embodiment, since the fuel vapor processing system 30 is provided in the internal combustion engine 10, even when the fuel vapor is discharged into the intake passage 11 by the system 30, the oxygen concentration of the intake air and the exhaust gas are exhausted. Will change the oxygen concentration. For this reason, if an abnormality determination based on the oxygen concentration of the intake air or the oxygen concentration of the exhaust gas is executed, the determination accuracy is significantly lowered.

  In order to avoid such a decrease in determination accuracy, the abnormality determination may be performed only when the fuel vapor processing system 30 stops discharging the fuel vapor to the intake passage 11, but in this case, There is a risk that it will not be possible to ensure a sufficient opportunity for executing the abnormality determination or the amount of fuel vapor discharged into the intake passage 11. In order to meet the recent demand for reduction in fuel consumption, it is conceivable to adopt a configuration in which the intake pressure PM during operation of the internal combustion engine 10 is increased to reduce the pumping loss. It is difficult to achieve both the securing of the execution opportunity and the securing of the discharge amount of the fuel vapor to the intake passage 11.

  In this regard, according to the present embodiment, even when the fuel vapor is discharged into the intake passage 11 by the fuel vapor processing system 30, the blow-by gas processing system is based on the accurately estimated PCV flow rate. The presence / absence of 40 abnormalities can be accurately determined. Therefore, compared with a device in which an abnormality determination based on the intake oxygen concentration and the exhaust oxygen concentration is performed, the abnormality determination execution opportunity for the blow-by gas processing system 40 and the amount of fuel vapor discharged into the intake passage 11 are determined. Both can be secured.

  Further, when the gas is discharged into the intake passage 11 by the blow-by gas processing system 40, the factor that changes the oxygen concentration of the intake air or the oxygen concentration of the exhaust gas is not the amount of the gas discharged to the intake passage 11, but the intake passage 11 This is the amount of the fuel component and oil component (specifically, hydrocarbon “HC”) contained in the gas discharged into the tank. The amount of HC contained in the gas discharged to the intake passage 11 is an amount obtained by multiplying the PCV flow rate and the HC concentration of the gas in the crankcase 24. This HC concentration changes in the operating state of the internal combustion engine 10. In addition, it is difficult to specify as it varies greatly. Therefore, in an apparatus that performs an abnormality determination based on the oxygen concentration of the intake air or the oxygen concentration of the exhaust gas, the oxygen concentration of the intake air or the oxygen concentration of the exhaust gas changes as the HC concentration in the crankcase 24 changes. This is unavoidable, and this contributes to a decrease in determination accuracy. In this respect, in the present embodiment, since the presence or absence of abnormality of the blow-by gas processing system 40 is determined based on the amount of gas passing through the gas discharge passage 42 (PCV flow rate), the HC of the gas in the crankcase 24 The determination can be performed with high accuracy without being affected by the density.

As described above, according to the present embodiment, the effects described below can be obtained.
(1) The throttle passage flow rate MT can be accurately calculated based on the passage intake amount MA and the throttle opening degree TA, and the estimated PCV flow rate MP is calculated by subtracting the throttle passage flow rate MT from the passage intake amount MA. Can do. Further, the reference flow rate MPb can be obtained based on the intake pressure PM. Then, by comparing the estimated PCV flow rate MP and the reference flow rate MPb, it is possible to accurately determine whether or not the blow-by gas processing system 40 is abnormal.

  (2) The process for calculating the estimated PCV flow rate MP and the process for calculating the reference flow rate MPb are performed on condition that a predetermined condition for determining that the change per unit time of the operating state of the internal combustion engine 10 is small is satisfied. I tried to run. Therefore, it is possible to accurately calculate values that match the actual situation as the estimated PCV flow rate MP and the reference flow rate MPb, and to accurately determine whether there is an abnormality in the blow-by gas processing system 40.

  (3) Since the condition including the condition that the change per unit time of the intake pressure PM is small (the [Condition C]) is set as the predetermined condition, the presence or absence of abnormality of the blow-by gas processing system 40 is accurately determined. Will be able to.

  (4) Even when fuel vapor is discharged into the intake passage 11 by the fuel vapor processing system 30, whether or not there is an abnormality in the blow-by gas processing system 40 based on the accurately estimated PCV flow rate is accurately detected. Can be determined. Therefore, compared with a device in which an abnormality determination based on the intake oxygen concentration and the exhaust oxygen concentration is performed, the abnormality determination execution opportunity for the blow-by gas processing system 40 and the amount of fuel vapor discharged into the intake passage 11 are determined. Both can be secured.

The embodiment described above may be modified as follows.
The predetermined condition can be arbitrarily changed as long as it can be determined that the change per unit time of the operating state of the internal combustion engine 10 is small.

  Instead of calculating the average value of the estimated PCV flow rate MP and using it for determining the presence or absence of abnormality, the estimated PCV flow rate MP itself is used for determining the presence or absence of abnormality at the timing when the estimated PCV flow rate MP is calculated. It may be.

  A method for comparing the estimated PCV flow rate MP and the reference flow rate MPb to determine whether there is an abnormality in the blow-by gas processing system 40 calculates, for example, a ratio (= MP / MPb) between the estimated PCV flow rate MP and the reference flow rate MPb. In addition, a method of comparing the same ratio with the determination value can be arbitrarily changed. In short, it is possible to determine “abnormal” when the estimated PCV flow rate MP and the reference flow rate MPb are deviated, and “no abnormality” when the estimated PCV flow rate MP and the reference flow rate MPb are not deviated. It is sufficient if it can be determined.

The present invention can also be applied to an internal combustion engine not equipped with a fuel vapor processing system.
The present invention is also applied to a blow-by gas processing system in which a mechanical operation valve that operates according to the difference between the pressure on the crankcase side in the gas discharge passage and the pressure on the intake passage side is provided as a PCV valve. be able to.

1 is a schematic diagram showing a schematic configuration of an internal combustion engine and peripheral devices to which an embodiment embodying an abnormality determination device according to the present invention is applied. The conceptual diagram which shows the relationship between the driving | running state of an internal combustion engine, and the request value of PCV flow volume. The flowchart which shows the execution procedure of an abnormality determination process. The graph which shows the relationship between the pressure ratio of the throttle upstream and downstream, and the throttle passage flow rate. The graph which shows the relationship between an intake pressure and a reference | standard flow volume.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Intake passage, 12 ... Throttle mechanism, 13 ... Throttle valve, 14 ... Throttle motor, 15 ... Combustion chamber, 16 ... Fuel injection valve, 18 ... Piston, 19 ... Crankshaft, 20 ... Exhaust passage, DESCRIPTION OF SYMBOLS 21 ... Oil tank, 22 ... Pump, 23 ... Fuel tank, 24 ... Crankcase, 25 ... Piston ring, 26 ... Cylinder inner wall surface, 27 ... Electronic control unit, 30 ... Fuel vapor processing system, 31 ... Canister, 32 ... Vapor Passage, 33 ... Purge passage, 34 ... Purge control valve, 35 ... Air introduction passage, 40 ... Blow-by gas treatment system, 41 ... New air introduction passage (first passage), 42 ... Gas discharge passage (second passage), 43 ... PCV valve.

Claims (5)

A first communication path that communicates a portion of the intake passage of the internal combustion engine that is downstream of the throttle valve in the intake flow direction and the inside of the crankcase; a PCV valve that changes a cross-sectional area of the first communication path; In an abnormality determination device that is applied to a blow-by gas processing system having a portion upstream of the throttle valve in the intake flow direction and a second communication path that communicates with the inside of the crankcase, and determines whether there is an abnormality in the system,
The amount of air passing through a portion upstream of the connection portion of the second communication passage in the intake passage in the intake flow direction, the opening of the throttle valve, and the downstream of the throttle valve in the intake passage in the intake flow direction Estimating means for estimating the amount of gas passing through the first communication path based on the pressure of the portion;
Calculating means for calculating a reference flow rate based on the pressure;
An abnormality determination device for a blowby gas processing system, comprising: a determination unit that determines whether there is an abnormality in the blowby gas processing system based on a comparison result between the gas amount and the reference flow rate. In the abnormality determination apparatus of the blowby gas processing system according to claim 1,
The condition that the estimation of the gas amount by the estimation unit and the calculation of the reference flow rate by the calculation unit are determined under the condition that a change per unit time of the operating state of the internal combustion engine is small is satisfied. An abnormality determination device for a blow-by gas processing system. In the abnormality determination apparatus of the blowby gas processing system according to claim 2,
The abnormality determination device for a blow-by gas processing system, wherein the predetermined condition includes a condition that a change per unit time in a pressure at a downstream side in the intake flow direction is small. In the abnormality determination apparatus of the blowby gas processing system according to any one of claims 1 to 3,
An abnormality determination device for a blow-by gas processing system, wherein the internal combustion engine is provided with a fuel vapor processing system for discharging and processing fuel vapor generated in a fuel tank into the intake passage. In the abnormality determination apparatus of the blow-by gas processing system according to any one of claims 1 to 4,
The estimating means obtains the amount of air passing through the throttle valve based on the opening degree of the throttle valve and the pressure, and calculates the amount of air obtained through the upstream portion in the intake flow direction. An abnormality determination device for a blow-by gas processing system, wherein an estimated value of the gas amount is obtained by subtracting from an amount.

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