JP2010096031A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine with a fuel vapor treatment device and a blow-by gas recirculation device, for accurately learning the concentration of fuel vapor of purge gas guided to an air intake passage by the fuel vapor treatment device based on a change in an engine combustion state. <P>SOLUTION: The internal combustion engine 100 includes the fuel vapor treatment device 40 for guiding the purge gas to an air intake manifold 10, and the blow-by gas recirculation device 50 for recirculating the blow-by gas to the air intake manifold 10. An electronic control device 60 guides the purge gas to the air intake manifold 10, and leans the concentration of the fuel vapor in the purge gas based on the combustion state of a fuel-air mixture. The blow-by gas recirculation device 50 includes an electronic control type PCV valve 53 for adjusting the recirculation amount of the blow-by gas. The electronic control device 60 limits the recirculation amount of the blow-by gas by forcibly reducing the opening degree of the PCV valve 53 before learning the concentration of the fuel vapor. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine that includes a fuel vapor processing device that introduces fuel vapor generated in a fuel supply system into an intake passage, and a blow-by gas recirculation device that circulates blow-by gas in a crankcase to the intake passage.

  2. Description of the Related Art A fuel vapor processing apparatus is known in which fuel vapor generated in a fuel supply system of an internal combustion engine is once adsorbed by a canister, and then the adsorbed fuel vapor is introduced into an intake passage as purge gas together with air (for example, Patent Document 1). reference). Here, when the purge gas is introduced into the intake passage in this way, the fuel contained in the purge gas burns in the combustion chamber together with the fuel injected by the fuel injection valve, so that the operating state of the internal combustion engine is accurately controlled. For this purpose, it is necessary to grasp the concentration of the fuel vapor contained in the purge gas. Here, as a method of detecting the fuel vapor concentration, a concentration learning process is performed in which when the purge gas is purged into the intake passage, the fuel vapor concentration is learned based on a change in the engine combustion mode (for example, air-fuel ratio). Can be adopted.

On the other hand, as a blow-by gas recirculation device for recirculating gas leaking from a combustion chamber to a crankcase in a combustion stroke of an internal combustion engine, so-called blow-by gas, into an intake passage, for example, the one described in Patent Document 2 is known. The blow-by gas recirculation device includes a breather passage that connects a crankcase and an intake passage of an internal combustion engine, and a PCV valve that is provided in the breather passage and opens based on a pressure difference between the crankcase and the intake passage. Yes. In an internal combustion engine employing such a blow-by gas recirculation device, when the PCV valve is opened, blow-by gas in the crankcase can be introduced into the combustion chamber through the intake passage and recombusted. Accordingly, it is possible to prevent the hydrocarbons contained in the blowby gas from being discharged into the atmosphere and to suppress the deterioration of the engine oil caused by the blowby gas.
JP 2005-163677 A JP 2006-250080 A

  By the way, in the internal combustion engine provided with both the above-described fuel vapor processing device and blow-by gas recirculation device, the following inconvenience may occur. That is, since the PCV valve of the blow-by gas recirculation device opens based on the pressure difference between the crankcase and the intake passage, the PCV valve opens when the fuel vapor concentration learning described above is executed. Sometimes. When the fuel vapor concentration learning is executed while the PCV valve is open as described above, purge gas is introduced into the intake passage and blow-by gas is circulated through the intake passage by the blow-by gas circulation device. . As a result, not only the fuel contained in the purge gas but also the fuel contained in the blow-by gas enters the combustion chamber through the intake passage, and the fuel vapor concentration and the actual concentration of the purge gas learned based on the change in the engine combustion mode Deviations may occur between them, and the fuel vapor concentration may not be learned accurately.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an internal combustion engine including a fuel vapor processing device and a blow-by gas recirculation device to an intake passage by a fuel vapor processing device based on a change in engine combustion state. It is an object of the present invention to provide a control device for an internal combustion engine that can accurately learn the concentration of fuel vapor in the introduced purge gas.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
According to the first aspect of the present invention, there is provided a fuel vapor processing apparatus that once adsorbs fuel vapor generated in a fuel supply system to a canister and introduces the adsorbed fuel vapor into a intake passage as a purge gas, and a blow-by gas in a crankcase Is applied to an internal combustion engine including a blow-by gas recirculation device that recirculates gas to the intake passage, and the purge gas is introduced into the intake passage by the fuel vapor processing device and is included in the purge gas based on the combustion state of the air-fuel mixture In the control device for an internal combustion engine provided with a concentration learning means for learning the concentration of the fuel vapor, the blow-by gas recirculation device is provided with an electronically controlled blow-by gas rectifying valve for adjusting the recirculation flow rate of the blow-by gas, Force the opening of the blow-by gas rectifying valve prior to concentration learning of the fuel vapor by concentration learning means Providing the recirculation flow limiting means for limiting the recirculation amount of the blow-by gas by reducing the gist of.

  According to this configuration, since the blow-by gas recirculation device includes the electronically controlled blow-by gas rectification valve that adjusts the flow rate of the blow-by gas, for example, the rectification that opens based on the pressure difference between the crankcase and the intake passage. Compared with the case where a blowby gas recirculation device including a valve is employed, the flow rate of blowby gas can be freely adjusted without depending on the pressure difference. Further, when the fuel vapor concentration learning is executed by restricting the flow rate of the blow-by gas by forcibly reducing the opening of the blow-by gas rectifying valve prior to the concentration learning of the fuel vapor, the blow-by gas The change in the combustion state of the air-fuel mixture caused by the fuel contained in the fuel gas entering the combustion chamber through the intake passage can be suppressed. Therefore, in an internal combustion engine having such a fuel vapor processing device and a blow-by gas recirculation device, the fuel vapor concentration of the purge gas introduced into the intake passage by the fuel vapor processing device is accurately learned based on the combustion state of the air-fuel mixture. Will be able to.

  As described in claim 2, it is desirable to employ a configuration in which the blow-by gas rectifying valve is fully closed prior to the fuel vapor concentration learning. With such a configuration, when the fuel vapor concentration learning is executed, the ring flow rate of the blow-by gas can be limited as much as possible, and the fuel vapor concentration can be learned more accurately.

  According to a third aspect of the present invention, in the control device for an internal combustion engine according to the first or second aspect, the actual air-fuel ratio of the internal-combustion engine is centered on a predetermined center value so as to be maintained in the vicinity of the target air-fuel ratio. Air-fuel ratio feedback control means for setting an air-fuel ratio feedback correction coefficient that repeatedly increases and decreases and correcting the fuel injection amount based on the air-fuel ratio feedback correction coefficient is provided, and the concentration learning means is configured to intake the purge gas by the fuel vapor processing device. The gist is to learn the concentration of the fuel vapor based on the degree to which the predetermined center value deviates from the predetermined reference value when introduced into the passage.

  When such an air-fuel ratio feedback control means is employed, if the concentration of fuel vapor contained in the purge gas introduced into the intake passage by the fuel vapor processing device changes, the actual air-fuel ratio changes, and the center of the feedback correction coefficient The degree to which the value deviates from the reference value changes based on the actual change in the air-fuel ratio. Therefore, according to the above configuration, the concentration of the fuel vapor contained in the purge gas can be accurately learned based on the degree to which the center value of the feedback correction coefficient deviates from the reference value when the purge gas is introduced into the intake passage. .

  According to a fourth aspect of the present invention, in the control apparatus for an internal combustion engine according to the third aspect, an air-fuel ratio learning value for compensating for a steady deviation between the actual air-fuel ratio and the target air-fuel ratio is learned. The gist of the present invention is that the fuel vapor concentration learning is performed by the concentration learning means on condition that the air-fuel ratio learning means is provided and learning of the air-fuel ratio learning value by the air-fuel ratio learning means is completed.

  There may be a steady deviation between the actual air-fuel ratio and the target air-fuel ratio due to variations in internal combustion engines, changes with time, and the like. When such a steady deviation occurs, the air-fuel ratio feedback correction coefficient changes based on this deviation, so the fuel vapor concentration can be accurately learned based on the degree to which the center value of the correction coefficient deviates from its reference value. There is a risk of disappearing.

  In this regard, according to the above configuration, the fuel vapor concentration learning is executed on the condition that learning of the air-fuel ratio learning value for compensating for a steady deviation between the actual air-fuel ratio and the target air-fuel ratio is completed. Thus, the fuel vapor concentration can be learned in a state where the steady deviation is compensated, and the influence of the deviation on the learning result of the fuel vapor concentration can be suppressed.

  When the blow-by gas is introduced into the intake passage when learning the air-fuel ratio learning value described above, the actual air-fuel ratio changes depending on the amount of fuel contained in the blow-by gas. You may not be able to learn.

  Therefore, as described in claim 5, the ring flow rate limiting means forcibly reduces the opening of the blow-by gas rectifying valve prior to learning of the air-fuel ratio learning value by the air-fuel ratio learning means. It is desirable to employ a configuration in which the ring flow rate of the blow-by gas is limited. By adopting such a configuration, it is possible to suppress the fuel contained in the blow-by gas from entering the combustion chamber when learning the air-fuel ratio learning value, and to the learning result of the air-fuel ratio learning value by introducing the blow-by gas. The influence of can be suppressed.

Hereinafter, an embodiment in which the control device for an internal combustion engine according to the present invention is embodied as an electronic control device that comprehensively controls an in-vehicle internal combustion engine will be described with reference to FIGS.
FIG. 1 is a schematic configuration diagram schematically showing an internal combustion engine and an electronic control device thereof according to the present embodiment. As shown in FIG. 1, a plurality of cylinders 1 (only one of which is shown in the figure) are formed in a cylinder block of the internal combustion engine 100, and a piston 2 reciprocates in these cylinders 1. Each is accommodated as possible. The piston 2 is connected to the crankshaft 5 via the conroad 4, and the reciprocating motion of the piston 2 is converted into the rotational motion of the crankshaft 5 by the conroad 4 during engine operation. The conload 4 and the crankshaft 5 are accommodated in a crankcase 1 a located below the cylinder 1.

  A plurality of combustion chambers 3 are defined by the top surface of the piston 2 and the inner wall of the cylinder 1. Above these combustion chambers 3, spark plugs 6 are respectively provided so as to face the pistons 2, and intake ports 7 and exhaust ports 8 communicating with the respective combustion chambers 3 are formed. The intake port 7 is connected to the intake manifold 10 to constitute a part of the intake passage, and the exhaust port 8 is connected to the exhaust manifold 20 to constitute a part of the exhaust passage. The intake manifold 10 is provided with a throttle valve 12 for adjusting the amount of intake air, and the exhaust manifold 20 purifies hydrocarbons (HC) and nitrogen oxides (NOx) contained in the exhaust. An exhaust purification catalyst 22 is provided. Further, an intake valve 11 for communicating / blocking the intake port 7 and the combustion chamber 3 and an exhaust valve 21 for communicating / blocking the exhaust port 8 and the combustion chamber 3 are provided at the upper part of the combustion chamber 3. . These intake / exhaust valves 11 and 21 are opened and closed by an intake camshaft and an exhaust camshaft connected to the crankshaft 5.

  The internal combustion engine 100 is provided with an in-cylinder injection valve 9 that directly injects fuel into the combustion chamber 3, and a fuel system 30 including a fuel tank 31 is connected to the in-cylinder injection valve 9. . The fuel stored in the fuel tank 31 is sucked up by the feed pump 32 and supplied to the high pressure pump, and is further pressurized by the high pressure pump and injected from the in-cylinder injection valve 9 into the combustion chamber 3.

  Connected to the fuel tank 31 is a fuel vapor processing device 40 that introduces fuel vapor generated in the fuel tank 31 into the intake passage. The fuel vapor processing apparatus 40 includes a canister 41 for temporarily adsorbing fuel vapor generated in the fuel tank 31, a vapor passage 42 for communicating the fuel tank 31 and the canister 41, and a canister 41 and an intake passage, specifically A purge passage 43 that communicates with a surge tank 13 formed downstream of the throttle valve 12 in the intake manifold 10 is provided. The fuel vapor generated in the fuel tank 31 is first introduced into the canister 41 through the vapor passage 42, condensed into liquid phase fuel, and once adsorbed by the adsorbent provided inside the canister 41. Then, when air is introduced through the air introduction passage 44 provided in the canister 41, the fuel adsorbed by the adsorbent is introduced into the surge tank 13 through the purge passage 43 as purge gas together with the air. Thus, the fuel contained in the purge gas introduced into the surge tank 13 is combusted in the combustion chamber together with the fuel injected by the in-cylinder injection valve 9. The purge passage 43 is provided with a purge control valve 45 capable of changing the amount of purge gas introduced into the intake manifold 10 (hereinafter referred to as “purge amount”). The purge control valve 45 is an electromagnetic valve whose opening is adjusted based on an electrical signal, and the opening is controlled based on a change in the control duty value DUP. In this embodiment, the purge control valve 45 is fully closed when the control duty value DUP is “0%”, and is fully opened when the control duty value DUP is “100%”.

  In addition, the internal combustion engine 100 according to the present embodiment is provided with a blow-by gas recirculation device 50 that recirculates gas that leaks from the combustion chamber 3 to the crankcase 1a in the combustion stroke, so-called blow-by gas, into the intake passage. The blow-by gas recirculation device 50 includes an introduction passage 51 that communicates a portion of the intake manifold 10 that is located upstream of the throttle valve 12 and the crankcase 1 a, and a downstream side of the throttle valve 12 in the crankcase 1 a and the intake manifold 10. The breather passage 52 communicates with the surge tank 13 located at the position, and the PCV valve 53 provided in the breather passage 52 for adjusting the ring flow rate of blow-by gas. With this configuration, when the PCV valve 53 is opened based on the engine operating state, a part of the intake air in the intake manifold 10 is introduced into the crankcase 1a through the introduction passage 51, and the blow-by gas in the crankcase 1a is It is introduced into the surge tank 13 through the breather passage 52. Note that the PCV valve 53 according to the present embodiment is an electronically controlled type in which the opening degree is adjusted based on an electrical signal regardless of the pressure difference between the crankshaft 5 and the intake manifold 10.

  The internal combustion engine 100 is provided with a plurality of sensors for detecting the engine operating state. For example, the intake manifold 10 is provided with an air flow meter 61 for detecting the amount of intake air and an opening sensor 62 for detecting the opening of the throttle valve 12. A crank sensor 63 for detecting the rotational position of the crankshaft 5 and the engine rotational speed NE is provided in the vicinity of the crankshaft 5, and the exhaust manifold 20 detects a rich / lean state of the air-fuel ratio. An air-fuel ratio sensor 64 is provided for this purpose. The cylinder block of the internal combustion engine 100 is provided with a water temperature sensor 65 for detecting the coolant temperature of the engine cooling water, and an accelerator opening for detecting the depression amount of the accelerator pedal is provided in the vicinity of the accelerator pedal. A degree sensor 66 is provided. The electronic control unit 60 detects the engine operating state based on the output signals of these sensors, and comprehensively controls various controls of the internal combustion engine 100.

  Hereinafter, the fuel injection amount control of the internal combustion engine 100 executed by the electronic control unit 60 of the present embodiment will be described with reference to the flowchart of FIG. The series of processes shown in FIG. 2 is executed for each engine cycle.

  In this control, after calculating the base value TAUb of the fuel injection amount based on the intake air amount Q detected by the air flow meter 61 (step S10), each calculation or learning is performed in other processing described later. A correction coefficient is read (step S20). Based on these correction coefficients, the base value TAUb is corrected to calculate the final value TAUf of the fuel injection amount (step S30), and the valve opening timing of the in-cylinder injection valve 9 is set based on this final value TAUf. Injection is performed (step S40). The correction coefficients described above include the following four.

(1) Air-fuel ratio feedback correction coefficient FAF
The air-fuel ratio feedback correction coefficient FAF is centered on a predetermined center value based on the amount of deviation between the actual air-fuel ratio and the target air-fuel ratio so that the actual air-fuel ratio is maintained in the vicinity of the target air-fuel ratio (theoretical air-fuel ratio). It is a correction coefficient that is set by repeatedly increasing and decreasing.

(2) Air-fuel ratio learning value KG
The air-fuel ratio learning value KG is a coefficient for compensating for a steady deviation between the actual air-fuel ratio and the target air-fuel ratio. Here, a steady deviation may occur between the actual air-fuel ratio and the target air-fuel ratio due to variations in the engine, changes over time, and the like. When such a steady deviation occurs, providing the air-fuel ratio feedback correction coefficient FAF calculated in the above-described air-fuel ratio feedback control with a function for compensating for the steady deviation ensures the stability of the control. Not preferred above. Therefore, for example, the engine operating state is divided into a plurality of regions based on the intake air amount Q and the like, and the air-fuel ratio learning value KG for compensating for a steady deviation between the actual air-fuel ratio and the target air-fuel ratio is used. By setting the fuel injection amount base value TAUb for each region, the control accuracy and responsiveness of the air-fuel ratio control can be improved.

(3) Purge rate PGR
The purge rate PGR is a coefficient indicating the ratio (flow rate ratio) of the purge gas introduced into the intake manifold 10 by the fuel vapor processing device 40 with respect to the intake air amount Q.

(4) Density learning value FGPG
The concentration learning value FGPG is a coefficient corresponding to the concentration of the fuel component contained in the purge gas introduced into the intake manifold 10. The influence of the purge gas on the air-fuel ratio is determined by the purge amount, in other words, the purge rate PGR and the concentration of the fuel component contained therein. Here, in the present embodiment, the purge rate PGR is directly controlled based on the opening degree of the purge control valve 45. Therefore, although the purge rate PGR can be directly grasped, the concentration of the fuel component is related. Cannot be grasped directly. Therefore, in the present embodiment, information regarding the concentration of the fuel component of the purge gas is indirectly grasped and stored as the concentration learning value FGPG.

Next, control for calculating or learning each of the above correction coefficients will be described.
[Air-fuel ratio feedback control]
FIG. 3 is a flowchart showing a processing procedure of air-fuel ratio feedback control for calculating the above-described air-fuel ratio feedback correction coefficient FAF. Note that the series of processing shown in FIG. 3 is repeatedly executed by the electronic control device 60 with a predetermined period.

  In this process, first, it is determined whether or not an execution condition for air-fuel ratio feedback control (hereinafter referred to as “F / B condition”) is satisfied based on the engine operating state detected by each of the sensors described above (step S110). ). Here, for example, when all of the following conditions are satisfied, it can be determined that the F / B condition is satisfied.

・ Do not start.
・ Do not cut fuel.
The cooling water temperature THW detected by the water temperature sensor 65 is equal to or higher than a predetermined value, that is, the internal combustion engine 100 is warmed up.

-The air-fuel ratio sensor 64 is activated.
The internal combustion engine 100 is not in a high load, high speed operation state.
When starting the internal combustion engine 100 or during cold operation, the fuel injection amount is increased in order to stabilize the operation, and the operation is performed at an air fuel ratio smaller than the stoichiometric air fuel ratio. In addition, the amount of fuel is similarly increased in order to suppress an increase in exhaust gas temperature during high load and high speed operation. Further, fuel injection itself is not executed during fuel cut. Since the air-fuel ratio cannot be detected unless the air-fuel ratio sensor 64 is activated, feedback control cannot be executed. Therefore, each of the above conditions is set.

  If it is determined that the F / B condition is not satisfied (step S110: NO), the air-fuel ratio feedback correction coefficient FAF is set to the reference value “1” (step S121), and this process is temporarily performed. finish.

  On the other hand, when it is determined that the F / B condition is satisfied (step S110: YES), based on the deviation amount between the actual air-fuel ratio of the air-fuel mixture detected by the air-fuel ratio sensor 64 and the target air-fuel ratio. The air-fuel ratio feedback correction coefficient FAF calculated in the previous control cycle is updated (step S120). Specifically, when the actual air-fuel ratio detected by the air-fuel ratio sensor 64 is in a rich state, the air-fuel ratio feedback correction coefficient FAF is decreased by a predetermined amount, and when it is in a lean state, the air-fuel ratio feedback correction is performed. The coefficient FAF is increased by a predetermined amount. Further, in order to improve the responsiveness and control accuracy of the air-fuel ratio feedback control, when the actual air-fuel ratio is switched from the lean state to the rich state, or from the rich state to the lean state, a so-called “skip value” is added to the air-fuel ratio feedback correction coefficient FAF. The air-fuel ratio feedback correction coefficient FAF is increased or decreased step by step.

  By such control, the air / fuel ratio feedback correction coefficient FAF is repeatedly set to increase / decrease around a predetermined center value based on the deviation amount between the actual air / fuel ratio and the target air / fuel ratio. It is maintained near the fuel ratio. In the present embodiment, the average value FAFAV between the air-fuel ratio feedback correction coefficient FAFL before the skip value addition / subtraction is executed and the air-fuel ratio feedback correction coefficient FAFR after the addition / subtraction is executed is the air-fuel ratio feedback correction. Used as the center value of the coefficient FAF. The difference between the average value FAFAV and the reference value “1” indicates the degree to which the air-fuel ratio feedback correction coefficient FAF deviates from the reference value “1”.

  After updating the air-fuel ratio feedback correction coefficient FAF as described above, the upper and lower limits of the air-fuel ratio feedback correction coefficient FAF are checked (step S130). This is a process for guarding the value of the air-fuel ratio feedback correction coefficient FAF within a range from a predetermined lower limit value to an upper limit value. After the air-fuel ratio feedback correction coefficient FAF is calculated in this way, this process is temporarily terminated.

[Purge control]
FIG. 4 is a flowchart showing a purge control processing procedure for appropriately adjusting the amount of purge gas introduced into the intake air in accordance with the engine operating state. The processing shown in FIG. 4 is executed by the electronic control device 60 as interruption processing at predetermined time intervals.

  In this process, first, it is determined whether or not an execution condition of the purge control process, that is, a condition for introducing purge gas from the canister 41 to the intake manifold 10 (hereinafter referred to as “purge condition”) is satisfied (step S210). ). Here, for example, when all of the following conditions are satisfied, it can be determined that the purge condition is satisfied.

・ Do not cut fuel.
-The air-fuel ratio feedback control described above is being implemented.
When it is determined that the purge condition is not satisfied (step S210: NO), the purge control valve 45 is fully closed by setting the control duty value DUP of the purge control valve 45 to 0% (step S221). ), This process is temporarily terminated.

  On the other hand, when it is determined that the purge condition is satisfied (step S210: YES), the air-fuel ratio feedback correction coefficient FAF updated in the above-described air-fuel ratio feedback control is read (step S220). Based on the intake air amount Q detected by the air flow meter 61 and the engine rotational speed NE detected by the crank sensor 63, the maximum purge rate PGRMX is calculated with reference to the calculation map (step S230). Here, the maximum purge rate PGRMX is a flow rate ratio of the purge amount to the intake air amount Q when the purge control valve 45 is driven with the control duty value DUP = 100%, that is, when the purge control valve 45 is fully opened.

  Next, based on the read air-fuel ratio feedback correction coefficient FAF and the like, in order to introduce purge gas according to the operating state of the internal combustion engine 100, a target value (hereinafter referred to as the flow rate ratio of the purge amount to the intake air amount Q). (Referred to as “target purge rate PGR”) (step S240).

  Next, a control duty value DUP of the purge control valve 45 necessary for ensuring the target purge rate PGR is calculated based on the following equation (1), and the purge control valve is calculated based on the calculated control duty value DUP. By transmitting a duty signal to 45, the opening degree of the control valve is controlled (step S250).

DUP ← (PGR / PGRMX) × 100 [%] (1)

[Learning process]
Since the steady deviation may change between the actual air-fuel ratio and the target air-fuel ratio due to changes over time or the like, the air-fuel ratio for learning the above-described air-fuel ratio learning value KG based on the air-fuel ratio feedback correction coefficient FAF It is necessary to execute a learning process.

  Further, since the concentration of the fuel contained in the purge gas changes as the engine operating state changes, it is necessary to learn the fuel vapor concentration in order to accurately grasp the amount of fuel contained in the purge gas. As a method for learning the fuel vapor concentration, for example, a concentration learning process for learning the concentration learning value FGPG based on a change in the air-fuel ratio feedback correction coefficient FAF when the above-described purge control is executed can be employed.

  By the way, in a conventional blow-by gas recirculation device having a PCV valve that opens based on a pressure difference between the crankcase and the intake passage, and an internal combustion engine having both a fuel vapor processing device, the following inconvenience may occur. . That is, since the PCV valve of the conventional blow-by gas recirculation device opens based on the pressure difference between the crankcase and the intake passage, the PCV valve opens when the above-described concentration learning process is executed. There is. When the concentration learning process is executed while the PCV valve is open as described above, purge gas is introduced into the intake passage, and blow-by gas is circulated through the intake passage by the blow-by gas recirculation device. As a result, not only the fuel contained in the purge gas but also the fuel contained in the blow-by gas enters the combustion chamber through the intake passage, and the concentration learning value FGPG learned based on the change in the air-fuel ratio feedback correction coefficient FAF and the actual concentration There is a possibility that a deviation occurs between and the concentration learning value FGPG cannot be accurately learned. Further, when the blow-by gas is introduced into the intake passage when learning the air-fuel ratio learning value KG, the actual air-fuel ratio changes depending on the amount of fuel contained in the blow-by gas. There is also a risk that it will not be possible to learn accurately.

  Therefore, in the present embodiment, as described above, the electronically controlled PCV valve 53 is adopted, and by appropriately controlling the PCV valve 53 in accordance with the above-described air-fuel ratio learning process and concentration learning process, such a PCV valve 53 is used. The inconvenience is suppressed.

  Hereinafter, learning processing including air-fuel ratio learning and concentration learning according to the present embodiment will be described with reference to the flowcharts of FIGS. 5 and 6 are repeatedly executed by the electronic control device 60 at a predetermined cycle.

  In this process, first, it is determined whether or not an execution condition for the air-fuel ratio learning process is satisfied (step S310). Here, for example, when all of the following conditions are satisfied, it can be determined that the execution condition is satisfied.

・ Air-fuel ratio feedback control is being executed.
-The cooling water temperature THW is equal to or higher than a predetermined temperature.
Here, when it is determined that the execution condition is not satisfied (step S310: NO), the series of processes is temporarily terminated without executing the air-fuel ratio learning process and the concentration learning process. On the other hand, if it is determined that this execution condition is satisfied (step S310: YES), the PCV valve 53 is forcibly fully closed (step S320), and then the air-fuel ratio learning process is executed (step S320). Step S330).

The flowchart of FIG. 6 shows the procedure of this air-fuel ratio learning process.
As shown in FIG. 6, when this process is executed, first, based on the intake air amount Q or the like, it is detected which of the plurality of operating regions the current engine operating state is divided in advance (step). S331). Then, the average value FAFAV of the air-fuel ratio feedback correction coefficient FAF when the above-mentioned “skip value” addition / subtraction is executed last time is read (step S332), and the current operation is performed based on the average value FAFAV. Learning is performed by updating the air-fuel ratio learning value KGi in the region i (step S333).

  Specifically, the air-fuel ratio learning value KGi is updated as follows. That is, when the average value FAFAV is larger than a preset update upper limit value FMX (for example, “1.02”), a predetermined gradual change value ΔK is added to the air-fuel ratio learning value KGi, and the average value FAFAV is When the update lower limit value FMN (for example, “0.98”) is smaller than a preset value, the gradual change value ΔK is subtracted from the air-fuel ratio learning value KGi. When the average value FAFAV is between the update upper limit value FMX and the update lower limit value FMN, it is determined that a steady deviation can be ignored between the actual air-fuel ratio and the target air-fuel ratio, and the air-fuel ratio learning value Do not change the value of KGi.

  After the air-fuel ratio learning process is completed as described above, the process proceeds to step S340 in FIG. 5 to determine whether or not the execution condition for the concentration learning process is satisfied. Here, for example, when all of the following conditions are satisfied, it can be determined that the execution condition is satisfied.

-The cooling water temperature THW is equal to or higher than a predetermined temperature.
The air-fuel ratio feedback correction coefficient FAF is not deviated from the center value “1” to a predetermined value or more, in other words, the air-fuel ratio learning value KG is stable.

-The purge control process has been executed.
Here, when it is determined that the execution condition of the concentration learning process is not satisfied (step S340: NO), the concentration learning process is not executed, and the fully closed state of the PCV valve 53 is released and the valve Normal control is resumed (step 360).

  On the other hand, when it is determined that the execution condition of the concentration learning process is satisfied (step S340: YES), the difference between the average value FAFAV used in the above-described air-fuel ratio learning process and the reference value “1”; Based on the target purge rate PGR set in the purge control described above, the concentration learning value FGPG is updated and learned through the following equation (2) (step S350).

FGPG ← FGPG + (FAFAV-1) / PGR (2)

Next, the fully closed state of the PCV valve 53 is released and normal control of the valve is resumed (step 360), and the air-fuel ratio learning process and the concentration learning process according to this embodiment are once ended.

According to the embodiment described above, the following effects can be obtained.
(1) An electronically controlled PCV valve 53 is employed as a rectifying valve for adjusting the ring flow rate of blow-by gas. Thereby, compared with the case where the rectifying valve which opens based on the pressure difference between the crankcase 1a and the intake passage is employed, for example, the ring flow rate of the blow-by gas is freely adjusted without depending on the pressure difference. Will be able to. In addition, the PCV valve 53 is forcibly fully closed prior to the concentration learning process to limit the flow rate of blow-by gas. Thereby, when the learning of the concentration learning value FGPG is executed, the change in the combustion state of the air-fuel mixture caused by the fuel contained in the blow-by gas entering the combustion chamber 3 through the intake passage can be suppressed as much as possible. It becomes like this. Therefore, in the internal combustion engine 100 including the fuel vapor processing device 40 and the blow-by gas recirculation device 50, the concentration corresponding to the fuel vapor concentration of the purge gas introduced into the intake passage by the fuel vapor processing device 40 based on the combustion state of the air-fuel mixture. The learning value FGPG can be learned accurately.

  (2) The concentration learning value FGPG is learned based on the difference between the average value FAFAV and the reference value “1”, in other words, the degree to which the center value of the air-fuel ratio feedback correction coefficient FAF deviates from the reference value “1”. did. Here, when the air-fuel ratio feedback control process is employed as in the present embodiment, if the concentration of the fuel vapor contained in the purge gas introduced into the intake passage by the blow-by gas recirculation device 50 changes, the actual change in the air-fuel ratio will occur. Accordingly, the degree to which the center value of the air-fuel ratio feedback correction coefficient FAF deviates from the reference value “1” changes. Therefore, the concentration learning value FGPG can be accurately learned based on the degree to which the center value of the air-fuel ratio feedback correction coefficient FAF deviates from the reference value “1”.

  (3) The learning of the concentration learning value FGPG is executed on the condition that the learning of the air-fuel ratio learning value KG is completed. Thereby, the concentration learning value FGPG can be learned in a state where the steady deviation between the actual air-fuel ratio and the target air-fuel ratio is compensated, and the influence of the deviation on the learning result of the concentration learning value FGPG is suppressed. be able to.

  (4) If the blow-by gas is introduced into the intake passage when learning the air-fuel ratio learning value KG, the actual air-fuel ratio changes depending on the amount of fuel contained in the blow-by gas. May not be able to learn correctly. Therefore, in the present embodiment, the PCV valve 53 is fully closed prior to learning of the air-fuel ratio learning value KG. Thereby, when learning the air-fuel ratio learning value KG, the fuel contained in the blow-by gas can be prevented from entering the combustion chamber 3, and the influence of the air-fuel ratio learning value KG on the learning result due to the introduction of the blow-by gas. Can be suppressed.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above embodiment, the PCV valve 53 is fully closed prior to learning the air-fuel ratio learning value KG. For example, if the learning result of the air-fuel ratio learning value KG due to the introduction of blow-by gas is small, learning of the concentration learning value FGPG starts after the learning of the air-fuel ratio learning value KG is completed. It is also possible to employ a configuration in which the PCV valve 53 is fully closed before.

  Further, when the change in the degree that the average value FAFAV deviates from the reference value “1” due to a steady deviation between the actual air-fuel ratio and the target air-fuel ratio can be ignored, the learning of the air-fuel ratio learning value KG is not necessarily performed. It is not necessary to execute the learning of the density learning value FGPG on the condition that is completed.

  In the above embodiment, the PCV valve 53 is fully closed in order to limit the flow rate of blow-by gas. However, the present invention is not limited to this. For example, the opening of the PCV valve 53 is set to an opening other than the fully closed. It is also possible to adopt a configuration that reduces the size to a minimum. By adopting such a configuration, it is possible to limit the ring flow rate of blow-by gas.

  In the above embodiment, the concentration learning value FGPG is learned based on the degree to which the center value of the air-fuel ratio feedback correction coefficient FAF deviates from the reference value “1” when the purge control process is executed. For example, when the purge control process is executed, the concentration learning value FGPG can be learned based on other parameters indicating the fuel state of the air-fuel mixture, such as the combustion temperature and the rotation speed.

1 is a schematic configuration diagram schematically showing an internal combustion engine and an electronic control device thereof according to an embodiment of the present invention. The flowchart which shows the process sequence of the fuel-injection control performed by the electronic controller which concerns on the same embodiment. The flowchart which shows the process sequence of the air fuel ratio feedback control performed by the electronic control apparatus which concerns on the same embodiment. 6 is a flowchart showing a procedure of purge control executed by the electronic control apparatus according to the embodiment. 6 is a flowchart showing the procedure of a learning process including an air-fuel ratio learning process and concentration learning, which is executed by the electronic control apparatus according to the embodiment. 7 is a flowchart showing a processing procedure of air-fuel ratio learning executed by the electronic control apparatus according to the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cylinder, 1a ... Crankcase, 2 ... Piston, 3 ... Combustion chamber, 4 ... Comload, 5 ... Crankshaft, 6 ... Spark plug, 7 ... Intake port, 8 ... Exhaust port, 9 ... In-cylinder injection valve, 10 DESCRIPTION OF SYMBOLS ... Intake manifold, 11 ... Intake valve, 12 ... Throttle valve, 13 ... Surge tank, 20 ... Exhaust manifold, 21 ... Exhaust valve, 22 ... Exhaust purification catalyst, 30 ... Fuel system, 31 ... Fuel tank, 32 ... Feed pump, DESCRIPTION OF SYMBOLS 40 ... Fuel vapor processing apparatus, 41 ... Canister, 42 ... Vapor passage, 43 ... Purge passage, 44 ... Air introduction passage, 45 ... Purge control valve, 50 ... Blow-by gas recirculation device, 51 ... Introduction passage, 52 ... Breather passage, 53 ... PCV valve, 60 ... electronic control device (concentration learning means, ring flow rate limiting means, air-fuel ratio feedback control means, air-fuel ratio learning means) 61 ... flow meter, 62 ... opening sensor, 63 ... crank sensor, 64 ... air-fuel ratio sensor, 65 ... water temperature sensor, 66 ... accelerator opening sensor, 100 ... internal combustion engine.

Claims (5)

A fuel vapor treatment device that once adsorbs fuel vapor generated in the fuel supply system to the canister and introduces the adsorbed fuel vapor into the intake passage as a purge gas, and a blowby gas that circulates the blowby gas in the crankcase to the intake passage A concentration that is applied to an internal combustion engine including a recirculation device, introduces the purge gas into the intake passage by the fuel vapor processing device, and learns the concentration of the fuel vapor contained in the purge gas based on a combustion state of an air-fuel mixture In an internal combustion engine control device comprising learning means,
The blow-by gas recirculation device is provided with an electronically controlled blow-by gas adjustment valve that adjusts the flow rate of the blow-by gas, and the blow-by gas adjustment valve is opened prior to the concentration learning of the fuel vapor by the concentration learning means. A control device for an internal combustion engine, comprising: an annular flow rate restricting means for restricting an annular flow rate of the blowby gas by forcibly reducing the degree. The control apparatus for an internal combustion engine according to claim 1,
The control device for an internal combustion engine, wherein the circulation flow rate restricting means fully closes the blow-by gas rectifying valve prior to the concentration learning of the fuel vapor by the concentration learning means. The control apparatus for an internal combustion engine according to claim 1 or 2, wherein an air-fuel ratio feedback correction coefficient that repeatedly increases and decreases around a predetermined center value to maintain the actual air-fuel ratio of the internal combustion engine in the vicinity of the target air-fuel ratio. An air-fuel ratio feedback control means for setting and correcting the fuel injection amount based on the same air-fuel ratio feedback correction coefficient, and the concentration learning means, when the purge gas is introduced into the intake passage by the fuel vapor processing device, A control apparatus for an internal combustion engine, which learns the concentration of the fuel vapor based on the degree to which a predetermined center value deviates from a predetermined reference value. The control apparatus for an internal combustion engine according to claim 3,
An air-fuel ratio learning means for learning an air-fuel ratio learning value for compensating for a steady deviation between the actual air-fuel ratio and the target air-fuel ratio, and learning of the air-fuel ratio learning value by the air-fuel ratio learning means is completed The control apparatus for an internal combustion engine, wherein the concentration learning means performs the concentration learning of the fuel vapor on the condition. The control apparatus for an internal combustion engine according to claim 4,
The recirculation flow rate limiting means restricts the recirculation flow rate of the blow-by gas by forcibly reducing the opening of the blow-by gas rectifying valve prior to learning of the air-fuel ratio learning value by the air-fuel ratio learning means. A control device for an internal combustion engine characterized by the above.

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