JP4769166B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly, to a flexible fuel vehicle, that is, an internal combustion engine for a vehicle that can be operated with gasoline fuel, ethanol fuel, or a mixed fuel of gasoline and ethanol. The present invention relates to a control device.

In Patent Document 1 below, in an internal combustion engine for a flexible fuel vehicle (hereinafter referred to as “FFV”) in which blow-by gas is recirculated to an intake system, the engine temperature is prescribed based on the boiling point of alcohol. The lower limit value of the correction range for the fuel supply amount according to the air-fuel ratio is increased when the temperature is within the temperature range, and the decrease correction amount of the fuel injection amount is increased when a large amount of alcohol vapor is recirculated. Disclosed.
JP-A-4-308336

  The influence of alcohol vapor is large mainly in a low load region where the fuel injection amount is small, and is small in a high load region where the fuel injection amount is large. However, when the alcohol vapor is recirculated in a large amount as in the above-described prior art, if the feedback control correction coefficient corresponding to the air-fuel ratio is decreased, the correction coefficient becomes a small value in a low load state. After that, when sudden acceleration is performed and the load becomes high, the intake air amount and the basic fuel injection amount increase rapidly, but the correction coefficient cannot be increased suddenly. The fuel ratio becomes lean.

  Accordingly, an object of the present invention is to provide a control device for an internal combustion engine that solves the above-described problems and ensures start performance and idle stability.

In order to solve the above-mentioned object, according to claim 1, an air-fuel ratio detecting means for detecting an air-fuel ratio in the exhaust gas, and a fuel injection amount in accordance with a deviation between the detected air-fuel ratio and the target air-fuel ratio. An air-fuel ratio correction coefficient calculating means for calculating the air-fuel ratio correction coefficient, a learning value calculating means for calculating the learning value by smoothing the air-fuel ratio correction coefficient, at least based on the calculated air-fuel ratio correction coefficient and the learning value The fuel injection amount calculating means for calculating the fuel injection amount, the blow-by gas recirculation device for recirculating the blow-by gas in the crankcase to the intake system, and the region where the influence of evaporation of the fuel mixed in the oil in the crankcase is large and determining the oil mixed fuel vaporization judging means or near Luke not, to calculate the oil mixed fuel subtraction term in accordance with the determination result of the oil mixed fuel vaporization judging means for subtracting from the fuel injection amount The controller of an internal combustion engine and a fuel amount subtraction means morphism, the fuel injection amount subtraction means, wherein it is determined that the oil in the fuel that is mixed in the crankcase is evaporated Rutotomoni, the air-fuel ratio correction factor When the value is smaller than a value obtained by subtracting a predetermined value from the learning value, the value of the oil-mixed fuel subtraction term is increased .

The control apparatus for an internal combustion engine according to claim 2 further includes engine load detection means for detecting an engine load of the internal combustion engine, and alcohol concentration determination for determining whether or not the alcohol concentration of the fuel is higher than a predetermined value. Means for determining whether or not the warming-up of the internal combustion engine has been completed, the warming-up completion determining means is not completed, the alcohol concentration of the fuel is higher than the predetermined value, and the fuel injection amount An oil mixed fuel amount estimated value calculating means for calculating an oil mixed fuel amount estimated value so as to increase every time when it is determined that the oil injected fuel amount is greater than a predetermined injection amount. When the estimated amount of mixed fuel is larger than the predetermined value and the engine load is smaller than the predetermined load, it is determined that the influence of the evaporation of the fuel mixed in the oil in the crankcase is in a large region. It was constructed as that.

According to the first aspect, the oil-mixed fuel is evaporated by calculating the oil-mixed fuel subtraction term according to the determination result of the oil-mixed fuel evaporation determining means and subtracting it from the fuel injection amount calculated from the air-fuel ratio correction coefficient. Even when the air-fuel ratio correction coefficient is not correct, it can be converged to a value that converges, and even if the intake air amount and the basic fuel injection amount increase due to sudden acceleration, the fuel injection amount corresponding to it Thus, the starting performance and idle stability can be ensured. Further, when the air-fuel ratio correction coefficient is smaller than a value obtained by subtracting a predetermined value from the learning value obtained by smoothing the air-fuel ratio correction coefficient, that is, when the fuel-incorporated fuel correction term is changed to the side where the fuel is decreased. Therefore, it is possible to prevent an unnecessary increase in the correction amount of oil-mixed fuel and to stably converge the air-fuel ratio correction coefficient.

In the control apparatus for an internal combustion engine according to claim 2, the above-described effect can be further obtained .

  The best mode for carrying out the control apparatus for an internal combustion engine according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing an overall control apparatus for an internal combustion engine according to an embodiment of the present invention.

  In FIG. 1, reference numeral 10 indicates a four-cylinder (cylinder) four-cycle internal combustion engine (only one cylinder is shown; hereinafter referred to as “engine”) mounted on an FFV (not shown). In the engine 10, the air (intake air) drawn from the air cleaner 12 and passing through the intake pipe 14 is adjusted in flow rate by the throttle valve 16 and flows through the intake manifold 18, and two intake valves (only one is shown) 20 are opened. When done, it flows into the combustion chamber.

  The throttle valve 16 is mechanically disconnected from an accelerator pedal (not shown) disposed on the floor surface of the FFV driver's seat, connected to a DC motor (actuator) 22, and driven by the DC motor 22 to open and close. . Thus, the opening degree of the throttle valve 16 is controlled by a DBW (Drive By Wire) method.

  A main injector 24 is disposed near the intake port in front of the intake valve 20. Fuel that is stored in the main fuel tank 26 and pumped up by the main fuel pump 28 disposed inside the main fuel tank 26 is pumped to the main injector 24 via the main fuel supply pipe 30.

  As the fuel stored in the main fuel tank 26, a mixed fuel of gasoline and ethanol (ethyl alcohol), specifically, a mixed fuel (E22) of 78% gasoline and 22% ethanol (E22) is ethanol of 0% gasoline and 100% ethanol. Alcohol fuel up to fuel (E100) is scheduled. Incidentally, the alcohol fuel has a stoichiometric air / fuel ratio that is richer than that of gasoline, and the deviation increases as the alcohol concentration increases.

  A sub-injector 32 is disposed upstream of the main injector 24 in the vicinity of the intake port. The sub fuel stored in the sub fuel tank 34 and pumped up by the sub fuel pump 36 is pumped to the sub injector 32 through the sub fuel supply pipe 38. As the sub fuel, gasoline fuel, E22 or the like is used.

  The main injector 24 and the sub injector 32 are electrically connected to an ECU (Electronic Control Unit) 40 through a drive circuit (not shown), and a drive signal indicating valve opening time is transmitted from the ECU 40 through the drive circuit. When supplied, the valve is opened, and fuel corresponding to the valve opening time is injected into the intake port. The injected fuel mixes with the air that flows in to form an air-fuel mixture (pre-air mixture), and flows into the combustion chamber when the intake valve 20 is opened. The sub fuel is used only when the engine 10 is started.

  A spark plug 44 is disposed in the combustion chamber. The spark plug 44 is connected to an ignition device (not shown) made of an igniter or the like. When an ignition signal is supplied from the ECU 40, the ignition device generates a spark discharge between the electrodes of the spark plug 44. The mixture is thereby ignited and burned, driving the piston 46 downward.

  A crankshaft (not shown) 50 is connected to the piston 46 and converts the vertical motion of the piston 46 into rotational motion inside the crankcase 48 below the cylinder block that encloses the piston 46. Reference numeral 50 denotes a pulsar plate attached thereto. ) Is housed. The lower part of the crankcase 48 constitutes an oil pan that receives oil (lubricating oil).

  Exhaust gas (exhaust gas) generated by combustion flows to the exhaust pipe 54 through the exhaust port 52 when two exhaust valves (not shown) are opened. A catalyst device 56 (consisting of a two-bed three-way catalyst) is disposed in the exhaust pipe 54. When the catalyst device 56 is in an active state, the exhaust gas is released into the atmosphere outside the engine after removing harmful components such as HC, CO, and NOx.

  The space above the liquid level of the main fuel tank 26 and the sub fuel tank 34 is connected to a canister 62 via charge passages 58 and 60, and the canister 62 is disposed on the intake pipe 14 via a purge passage 64. Connected downstream. The purge passage 64 is provided with a purge control valve 64a composed of an electromagnetic valve, and opens the purge passage 64 when excited.

  In the configuration described above, the fuel vapor evaporated from the main fuel tank 26 and the sub fuel tank 34 flows to the canister 62 through the charge passages 58 and 60 and is adsorbed by the adsorbent 62a accommodated therein. When the purge control valve 64a is excited inside the canister 62, a negative pressure is applied from the intake pipe 14, and the adsorbed fuel vapor is taken in through the purge passage 64 together with fresh air introduced from the atmosphere opening hole 62b. Purged into the system.

  A PCV (Positive Crankcase Ventilation) hole is formed in the upper part of the crankcase 48 and is connected to the downstream side of the position where the throttle valve 16 is disposed in the intake pipe 14 by a reflux passage 68. The recirculation passage 68 is provided with a check valve 68a, and the alcohol vapor mixed in the oil in the crankcase pushes and opens the check valve 68a when the pressure exceeds a predetermined pressure, and is purged to the intake system through the recirculation passage 68 as blow-by gas ( Reflux).

  The cylinder head above the cylinder block is provided with a valve operating mechanism 70 that is operated by hydraulic pressure, and changes the valve timing and lift amount of the intake valve 20 between two characteristics, high and low.

  A crank angle sensor 72 is disposed in the vicinity of the crankshaft of the engine 10, and a cylinder discrimination signal based on the rotation of the pulsar plate 50 described above, and a TDC signal indicating a TDC (top dead center) of each cylinder or a crank angle in the vicinity thereof. And a crank angle signal obtained by subdividing the TDC signal.

  An air flow meter 74 having a temperature detecting element is disposed in the vicinity of the air cleaner 12 and outputs a signal corresponding to the amount of air (intake air) Q taken from the air cleaner 12 and the intake air temperature TA.

  A MAP sensor 76 is disposed downstream of the throttle valve 16 in the intake pipe 14 and outputs a signal indicating the intake pipe pressure PBA in absolute pressure. A throttle opening sensor 78 is disposed in the throttle valve 16. A signal corresponding to the position (throttle opening) TH is output.

  A water temperature sensor 80 is disposed in a cooling water passage (not shown) of the engine 10 to output a signal corresponding to the engine cooling water temperature TW, and a knock sensor 82 is disposed in the cylinder block, so that vibrations generated in the engine 10 are detected. A corresponding signal is output.

A wide area air-fuel ratio sensor 84 is disposed upstream of the catalyst device 56 in the exhaust system, and outputs a signal corresponding to the oxygen concentration in the exhaust gas in a wide range from the stoichiometric air-fuel ratio to rich or lean. Based on the output of the wide area air-fuel ratio sensor 84, the detected air-fuel ratio KACT is calculated as an equivalence ratio. Further, an O ₂ sensor 86 is disposed between the catalyst beds of the catalyst device 56, and outputs a signal that reverses whenever the oxygen concentration in the exhaust gas changes from the stoichiometric air-fuel ratio to rich or lean.

  A fuel level sensor 88 is disposed in the main fuel tank 26 and outputs a signal corresponding to the fuel level.

  An accelerator opening sensor 90 is provided in the vicinity of the accelerator pedal, and outputs a signal corresponding to the accelerator position (indicating the engine load) AP indicating the amount by which the driver depresses the accelerator pedal. A vehicle speed sensor 92 is provided in the vicinity of the drive shaft (not shown), and a pulse signal is output per rotation of the drive shaft, and an atmospheric pressure sensor 94 is provided at an appropriate position of the FFV, depending on the atmospheric pressure PA. Output the signal.

  The output of the sensor group described above is input to the ECU 40. The ECU 40 includes a microcomputer, and includes a CPU, ROM, RAM, A / D conversion circuit, input / output circuit, and counter (all not shown). The ECU 40 counts the crank angle signal among the input signals to calculate (detect) the engine speed NE, and counts the output of the vehicle speed sensor 92 to calculate (detect) the vehicle speed VP.

  Based on the input value and the calculated value, the ECU 40 calculates the fuel injection amount and the like according to the command stored in the ROM, as described below, and calculates the intake valve 20 from the engine speed NE and the intake pipe absolute pressure PBA. The valve timing and the lift amount are changed between two characteristics, high and low.

  FIG. 2 is a block diagram functionally explaining the operation of the ECU 40.

  Reference numeral 40a denotes a fuel injection amount calculation block, in which a fuel injection amount TOUT to be supplied to the engine 10 is calculated according to the detected operating state.

  That is, the basic fuel injection amount TIM is calculated according to the engine load, and in the air-fuel ratio feedback control for controlling the detected air-fuel ratio KACT to the target air-fuel ratio KCMD (more precisely, the target air-fuel ratio correction coefficient KCMD). An air-fuel ratio correction coefficient (air-fuel ratio feedback correction coefficient) KAF is calculated in accordance with the deviation of the difference, and other correction coefficients such as an alcohol concentration correction coefficient KREFBS are calculated to correct the basic fuel injection amount, thereby fuel injection. A quantity TOUT is calculated.

  In the fuel injection amount calculation block 40a, the limit value of the air-fuel ratio correction coefficient KAF is set, and when the limit value is changed when the alcohol concentration is learned, when the air-fuel ratio correction coefficient KAF reaches the limit value, It is configured to change the limit value.

  Based on the calculated fuel injection amount TOUT, the main injector 24 is driven. Since the alcohol fuel has poor startability when the engine coolant temperature TW is low, the sub fuel is injected by driving the sub injector 32 in addition to the main injector 24 when the engine 10 is started.

  Reference numeral 40b denotes an alcohol concentration learning block in which the alcohol concentration contained in the fuel is learned based on the air-fuel ratio correction coefficient KAF. In other words, the alcohol concentration correction coefficient KREFBS is updated by calculating the alcohol concentration learning value KREFX by smoothing the air-fuel ratio correction coefficient KAF and multiplying it by the previous alcohol concentration correction coefficient KREFBS. The alcohol concentration correction coefficient KREFBS is sent to the block 40a.

  Reference numeral 40c denotes an ignition timing calculation block in which an ignition timing to be supplied to the engine 10 is calculated according to the detected operating state, and ignition of the spark plug 44 is controlled based on the calculated ignition timing. .

  Reference numeral 40d denotes a throttle opening control value calculation block, in which a throttle opening control value is calculated, and the DC motor 22 is driven based thereon.

  FIG. 3 is a flowchart showing the processing in the fuel injection amount calculation block 40a. The illustrated program is executed at a predetermined crank angle near the TDC of each cylinder.

  In the following description, it is obtained by multiplying the start-time increase correction term KAST, the acceleration correction term KACC calculated according to the acceleration, and the deceleration correction term KDEC calculated according to the deceleration calculated in a separate routine in S10. Let the product be ktotaltmp.

  Next, the routine proceeds to S12, where the intake air temperature correction term KTA calculated in accordance with the intake air temperature TA, the atmospheric pressure correction term KPA calculated in accordance with the atmospheric pressure PA, and the engine cooling water temperature TW, which are similarly calculated in another routine. Is multiplied by the water temperature correction term KTW calculated in this way, and the product thus obtained is defined as ktatwpa.

  Next, in S14, the two correction terms obtained by the processing of S10 and S12 are multiplied, and the obtained value is set as the multiplication correction term integrated value KTTL.

  Next, in S16, the fuel injection amount TOUT to be supplied to the engine 10 is calculated according to the equation shown.

  In the equation shown in S16, KREFBS: alcohol concentration correction coefficient, KAF: air-fuel ratio correction coefficient, KCMD: target air-fuel ratio or target air-fuel ratio correction coefficient (the air-fuel ratio is indicated by the equivalent ratio in the same manner as the detected air-fuel ratio KACT. KTTL: Multiplication correction term integrated value, TIM (basic fuel injection amount after warm-up, preset characteristics (map)) Engine load Gair (calculated by searching for the amount of air used for one combustion obtained by dividing the output Q of the air flow meter 74 by the engine speed NE), KEVACT: canister purge (intake system) Correction coefficient (fuel vapor recirculated to the fuel), KCTMFFV: alcohol transpiration correction coefficient (correction coefficient of alcohol vapor mixed in oil (lubricating oil)) A. All fuel injection amounts including the final fuel injection amount TOUT are defined by the valve opening time of the main injector 24.

  FIG. 4 is a flowchart showing processing in the alcohol concentration learning block 40b. The illustrated program is also executed at a predetermined crank angle near the TDC of each cylinder.

  In the following, it is determined whether or not the bit of the flag F_PGDLY is set to 1 in S100. Since this bit is set to 1 when canister purge is stopped in another routine, the determination in S100 means whether or not canister purge is stopped.

  When the result in S100 is negative, the subsequent processing is skipped. When the result is affirmative, the process proceeds to S102, and it is determined whether or not the engine speed NE exceeds a predetermined high speed NKREFXH. When the result in S102 is affirmative, the subsequent processing is skipped. When the result is negative, the process proceeds to S104, and it is determined whether or not the intake air temperature TA exceeds a predetermined high intake air temperature TAREF.

  When the result in S104 is affirmative, the subsequent processing is skipped. When the result is negative, the process proceeds to S106, and it is determined whether or not the bit of F_OCTMMCND is “1”. Since this bit is set to 1 when this flag is in a region where the influence of transpiration of alcohol fuel mixed in oil is large in another routine, the determination in S106 is to determine whether or not it is in such a region. Equivalent to.

  When the result in S106 is negative, the program proceeds to S108, in which it is determined whether or not the intake pipe absolute pressure PBA exceeds a predetermined low load value PBAREFXL. Judge whether it is less than.

  When the result in S106 is affirmative, the routine proceeds to S112, where it is determined whether or not the intake pipe absolute pressure PBA exceeds a predetermined low load value PBAREFXLFFV. When the result is negative, the subsequent processing is skipped and when the result is affirmed. Proceed to S110.

  When the result in S110 is negative, the subsequent processing is skipped, and when the result is affirmative, the process proceeds to S114. As shown in the figure, the weighted average is performed using the weighting coefficient C to smooth the air-fuel ratio correction coefficient KAF and A density learning value KREFX is calculated.

  As described above, when the canister purge is stopped and the operating state of the engine 10 is in the predetermined operating range, the alcohol concentration learning value KREFX is calculated by smoothing the air-fuel ratio correction coefficient KAF.

  FIG. 5 is a flowchart showing similarly the processing of the alcohol concentration learning block 40b. The illustrated program is also executed at a predetermined crank angle near the TDC of each cylinder.

  In the following, it is determined whether or not the bit of the flag F_FSPAFFB is set to 1 in S200. Since this bit is set to 1 when the wide area air-fuel ratio sensor 84 has failed in another routine, the processing of S200 is equivalent to judging it.

  When the result in S200 is negative, the program proceeds to S202, in which it is determined whether or not the bit of the flag F_FCFFVDN is set to 1.

  FIG. 6 is a time chart for explaining the alcohol concentration learning.

  When the bits of F_FC (fuel cut execution flag) and F_KALCOK (alcohol concentration correction coefficient preparation completion flag) shown in FIG. 6 are set to 1, the flag of S202 is set to 1 in another routine.

  When the result in S202 is affirmative, the program proceeds to S204, in which it is determined whether or not the bit of the flag F_KREFBSON is set to 1. This flag is set to 1 when updating of the alcohol concentration correction coefficient, in other words, when the execution of learning of alcohol concentration is completed, so the determination in S204 is usually denied and the processing proceeds to S206, as shown in the figure. The product obtained by multiplying the alcohol concentration correction coefficient KREFBS by the alcohol concentration learning value KREFX is defined as KREFBST.

  Next, the process proceeds to S208, and when KREFBST exceeds the max value or falls below the min value, limit processing is performed to limit it, and the processed value is set to KREFBS. The process proceeds to S210, and the bit of the flag F_KREFBSON described above is set to 1 . If the determination at S204 is affirmative, S206 to S210 are skipped.

  On the other hand, when the result in S202 is NO, the program proceeds to S212, in which it is determined whether or not the bit of the flag F_WOT is set to 1. This flag is set to 1 when the target air-fuel ratio KCMD (target air-fuel ratio correction coefficient KCMD) is enriched to protect the catalyst device 56 in another routine. To do.

  When the result in S212 is affirmative, the program proceeds to S214, in which it is determined whether the F_AFFB bit is set to 1. This flag is set to 1 when the above-described air-fuel ratio feedback control is executed in another routine, so that it is determined in S214.

  When the result in S214 is negative, the program proceeds to S216, in which it is determined whether or not the bit of the alcohol concentration correction coefficient preparation completion flag F_KALCOK is set to 1. When the result in S216 is affirmative, the process proceeds to S204. When the result is negative, the process proceeds to S218, and the bit of the flag F_KREFBSON is reset to 0. The same applies when the result is negative in S212 or positive in S214. If the result in S200 is affirmative, the program proceeds to S220 and S222, and values such as the alcohol concentration correction coefficient are set to 1.0 (no correction).

  The alcohol concentration learning will be described with reference to FIG. 6. In this embodiment, the alcohol concentration is learned (detected) based on the alcohol concentration learning value KREFX obtained by smoothing the air-fuel ratio correction coefficient KAF. E100 to E22 are planned as fuels, but the alcohol concentration correction coefficient KREFBS is set to an initial value so as to be a value corresponding to E64 in the middle (1.0, no correction).

  As shown at the left end of FIG. 6, when the fuel is switched to E100 by refueling when using E64, the air-fuel ratio correction coefficient KAF and the alcohol concentration learning value KREFX that changes the same change accordingly, and the alcohol concentration correction coefficient Is corrected to 1.2.

  After that, when the fuel is switched to E22 by refueling from the flag F_REFUELFFFV (refueling determination) at the end, the air-fuel ratio correction coefficient KAF and the learning value KREFX are inverted, and the alcohol concentration correction coefficient is corrected to 0.8. The

  Based on the above, the reduction correction of the fuel injection amount by the oil-mixed fuel, which is a feature of this embodiment, will be described.

FIG. 7 is a flowchart showing a process for determining the possibility of transpiration (evaporation) due to alcohol mixed in the process. The illustrated program is executed at a predetermined crank angle near TDC for each cylinder in the fuel injection amount calculation block 4 0a.

  Explaining below, in S300, it is determined whether or not the engine cooling water temperature TW is equal to or higher than the warm-up determination water temperature TWOCNTMFFV. If the determination is negative, it is determined that the engine 10 has not been warmed up. The total fuel injection amount USEDGAS from the start of 10 to the present is integrated, and the integrated value is held (stored) in UGSOCTMFFV.

  Next, in S304, it is determined whether or not the calculated alcohol concentration correction coefficient KREFBS is equal to or greater than a predetermined value KRBSOCTMFFV, in other words, whether or not the alcohol concentration of the fuel is high. When the result in S304 is affirmative, the program proceeds to S306, in which it is determined whether the calculated fuel injection amount TOUT is equal to or greater than a predetermined value TOUTOCTMFFV, that is, whether the alcohol injection amount is large.

  When the result in S306 is affirmative, the program proceeds to S308, in which a predetermined value DCTOCCTMP is added to the counter value COTMTMFFV for increase correction. Next, in S310, the bit of the flag F_OCTMMCND is reset to 0. This flag will be described later.

  The processes from S300 to S310 are processes for estimating the amount of fuel mixed in the oil from the number of occurrences of the condition that the fuel drops to the lower part of the crankcase 48 during the warm-up, and are subtracted from the fuel injection amount. This is the work to determine the basis for calculating the amount of evaporation. The reason why S308 is skipped when the determination in S304 or S306 is negative is that when the alcohol concentration is low or the fuel injection amount is small, the condition for the fuel to drip below the crankcase 48 is not satisfied.

  On the other hand, if the determination in S300 is affirmative, it is determined that the warm-up has been completed, and the process proceeds to S312, where the total fuel injection amount before completion of warm-up is retained from the total fuel injection amount USEDGAS integrated in another routine (not shown). UGSOCTMFFV is subtracted and the resulting difference is taken as DUGSOCTMFFV. This value DUGSOCTMFFV means the total fuel injection amount after completion of warm-up.

  Next, in S314, whether or not the total fuel injection amount after completion of warm-up calculated in S312 is greater than or equal to a predetermined value DUGSOCTMFFVL, in other words, the total fuel injection amount after warm-up (total heat generation amount) is greater than or equal to a predetermined value. Then, it is determined whether or not the oil temperature has become equal to or higher than a predetermined value (higher than the temperature at which oil-mixed fuel evaporates). If the result is affirmative, the process proceeds to S316, and the predetermined value DCTOCCTMM is subtracted from the counter value COTMTMFFV to correct for decrease. .

  Next, in S318, it is determined whether or not the counter value COCTMFFV is greater than or equal to a predetermined value CTOCTMFFVO. If the result in S318 is affirmative, it is determined that the amount of fuel mixed in the oil is large and evaporates from the oil, so that the process proceeds to S320, whether the intake air amount GAIR is less than or equal to the predetermined value GAIROCTMFFV, in other words, the load on the engine 10 is low. Determine whether or not.

  When the result in S320 is affirmative, since the fuel in the oil has evaporated and the load is low, it is determined that the influence of transpiration (evaporation) due to the alcohol mixed in the oil is large, the process proceeds to S322, and the flag F_OCTMMCND is set. Set the bit to 1.

  On the other hand, when the result in S314, S318, or S320 is negative, the influence is not determined to be large, so the process proceeds to S324, and the bit of the flag is reset to 0. Thus, setting the bit of this flag to 1 means that the influence of transpiration (evaporation) due to the oil-containing alcohol is determined to be large.

  FIG. 8 is a flowchart showing the calculation process of the oil-mixed fuel subtraction term executed in parallel with the process of FIG. The illustrated program is also executed at a predetermined crank angle near the TDC of each cylinder in the fuel injection amount calculation block 40a.

  In the following description, it is determined in S400 whether or not the bit of the flag F_OCTMMCND is set to 1. If the determination is affirmative, the process proceeds to S402, where the alcohol concentration learning value KREFX (the air-fuel ratio correction coefficient KAF described above should converge) The predetermined value DKRFKCTMFFV is subtracted from the (convergence value), and the value thus obtained is defined as dkrfkctmffv.

  Next, in S404, it is determined whether or not the calculated air-fuel ratio correction coefficient KAF is less than this value. When the result in S404 is negative, the subsequent processing is skipped. When the result is affirmative, the air-fuel ratio correction coefficient KAF is smaller than the convergence value KREFX by a predetermined value DKRFKCTMFFV, that is, by a predetermined value or more. In step S406, the value DKCTMFFV in the oil-mixed fuel subtraction term KCTMFFV is added and corrected for increase.

  Next, in S408, when the corrected oil-mixed fuel subtraction term KCTMFFV exceeds the maximum value, limit processing is performed to limit it. As a result, in S20, the fuel injection amount TOUT is subtracted by the oil-mixed fuel subtraction term KCTMFFV.

  When the determination in S400 is negative, it is not determined that the influence of transpiration (evaporation) due to the oil-mixed alcohol is large. In other words, it is determined that the fuel mixed in the oil is not evaporated so as to affect it. From S410, the oil-mixed fuel subtraction term KCTMFFV is set to zero.

In this embodiment, as described above, the air-fuel ratio detecting means (wide-area air-fuel ratio sensor 84) for detecting the air-fuel ratio in the exhaust, and the fuel injection amount according to the deviation between the detected air-fuel ratio KACT and the target air-fuel ratio KCMD. Air-fuel ratio correction coefficient calculation means (fuel injection amount calculation block 40a) for calculating the air-fuel ratio correction coefficient KAF of TOUT, and learning value calculation means for calculating the learning value (alcohol concentration learning value KREFX) by smoothing the air-fuel ratio correction coefficient KAF When the air-fuel ratio correction coefficient KAF and the learning value to be at least the calculated fuel injection amount calculating means for calculating the fuel injection amount TOUT based on (alcohol concentration learned value KREFX) (fuel injection amount calculation block 40a), the crank blow-by gas recirculation system recirculates blow-by gas in the case 48 to the intake system (recirculation passage 68) in the crankcase And impact of evaporation of the fuel mixed into the oil is large area near Luca whether judges oil mixed fuel evaporative determination means (fuel injection amount calculation block 40a, S300 from S324, S400 from S410), the oil mixed fuel evaporative determination An internal combustion engine (engine) 10 comprising: an injected fuel amount subtraction means (fuel injection amount calculation blocks 40a, S20, S400 to S410) for calculating an oil-mixed fuel subtraction term according to the determination result of the means and subtracting it from the fuel injection amount . In the control device, the injected fuel amount subtracting means determines that the fuel mixed in the oil in the crankcase has evaporated, and the air-fuel ratio correction coefficient KAF is the learned value (alcohol concentration learned value KREFX). When the value is smaller than the value obtained by subtracting the predetermined value DKRFKCTMFFV from To increase the value of Sanko (from S400 S406) was as configuration.

In this way, by calculating the oil-mixed fuel subtraction term KCTMFFV according to the determination result of the oil-mixed fuel evaporation determining means and subtracting it from the fuel injection amount TOUT calculated from the air-fuel ratio correction coefficient KAF or the like, the oil-mixed fuel is evaporated Even when the air-fuel ratio correction coefficient KAF is not used, the air-fuel ratio correction coefficient KAF can be converged to a value that converges (alcohol concentration learning value KREFX), and the intake air amount GAIR and the basic fuel injection amount TIM are increased by rapid acceleration. However, it is possible to inject a fuel injection amount corresponding to the fuel injection amount, thereby ensuring start performance and idle stability. Further, when the air-fuel ratio correction coefficient KAF is smaller than the value obtained by subtracting the predetermined value DKRFKCTMFFV from the learning value (alcohol concentration learning value KREFX) obtained by smoothing the air-fuel ratio correction coefficient, that is, on the side of reducing the fuel. Since the oil-mixed fuel correction term KCTMFFV is increased when it changes, an unnecessary increase in the oil-mixed fuel correction amount can be prevented and the air-fuel ratio correction coefficient KAF can be converged stably.

Further, engine load detection means (air flow meter 74) for detecting the engine load of the internal combustion engine, and alcohol concentration determination means (fuel injection amount calculation blocks 40a, S304) for determining whether or not the alcohol concentration of the fuel is higher than a predetermined value. ), A warm-up completion determination means (fuel injection amount calculation blocks 40a, S300) for determining whether or not the warm-up of the internal combustion engine has been completed, and the alcohol concentration of the fuel has not been completed. An oil-incorporated fuel amount estimated value calculating means for calculating an oil-injected fuel amount estimated value (counter value COTMFFV) so as to increase every time it is determined that the fuel injection amount is greater than a predetermined injection amount. (Fuel injection amount calculation blocks 40a, S300 to S308), and the oil-mixed fuel evaporation determining means When the value (counter value COTMTMFFV) is larger than the predetermined value CTOCTMFFVO and the engine load (intake air amount GAIR) is smaller than the predetermined load (predetermined value GAIROCTMFFV), the influence of evaporation of fuel mixed in the oil in the crankcase is affected. It was configured so as to be determined to be in a large area (S318 to S322) .

1 is a schematic diagram showing an overall control apparatus for an internal combustion engine according to an embodiment of the present invention. It is a block diagram explaining operation | movement of the apparatus shown in FIG. 1, more specifically operation | movement of ECU (electronic control unit) in the apparatus shown in FIG. 3 is a flowchart showing a process for calculating a fuel injection amount TOUT in a fuel injection amount calculation block shown in FIG. 2. It is a flowchart which shows the process of the alcohol concentration learning block of FIG. FIG. 3 is a flow chart similarly showing processing of the alcohol concentration learning block of FIG. 2. FIG. It is a time chart explaining the alcohol concentration learning of FIG. FIG. 3 is a flowchart showing an influence possibility determination process of transpiration (evaporation) due to oil-mixed alcohol in the process of the fuel injection amount calculation block of FIG. 2. It is a flowchart which shows the calculation process of the oil-mixed fuel subtraction term in the process of the fuel injection amount calculation block performed in parallel with the process of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Internal combustion engine (engine), 16 Throttle valve, 22 DC motor, 24 Main injector, 26 Main fuel tank, 40 ECU (electronic control unit), 44 Spark plug, 56 Catalytic device, 62 Canister, 68 Reflux passage (blow-by gas) Reflux unit), 70 Valve mechanism, 72 Crank angle sensor, 74 Air flow meter, 76 MAP sensor, 80 Water temperature sensor, 84 Wide area air-fuel ratio sensor, 90 Accelerator opening sensor, 92 Vehicle speed sensor, 94 Atmospheric pressure sensor

Claims (2)

And air-fuel ratio detecting means for detecting an air-fuel ratio in the exhaust, and air-fuel ratio correction coefficient calculating means for calculating an air-fuel ratio correction coefficient of the fuel injection quantity in accordance with the deviation between the detected air-fuel ratio and the target air-fuel ratio, the A learning value calculating means for calculating a learning value by smoothing an air-fuel ratio correction coefficient ; a fuel injection amount calculating means for calculating the fuel injection amount based on at least the calculated air-fuel ratio correction coefficient and the learning value; and a crankcase a blow-by gas recirculation system recirculates blow-by gas in the inner to the intake system, and oil entrained high impact areas near Luca whether judges oil mixed fuel vaporization judging means of the evaporation of the fuel in the crankcase, the a control system for an internal combustion engine having a fuel injection amount subtraction means the determination result of the oil mixed fuel vaporization judging means calculates the oil mixed fuel subtraction term in accordance subtracted from the fuel injection amount There are, the injection fuel quantity subtraction means, fuel mixed into the oil in the crankcase is determined to be evaporated Rutotomoni, value the air-fuel ratio correction coefficient is obtained by subtracting a predetermined value from the learning value When the value is smaller than the value, the value of the oil-mixed fuel subtraction term is increased . Further, engine load detection means for detecting the engine load of the internal combustion engine, alcohol concentration determination means for determining whether or not the alcohol concentration of the fuel is higher than a predetermined value, and whether or not warming up of the internal combustion engine is completed A warm-up completion determining unit for determining, and the warm-up is not completed, and the alcohol concentration of the fuel is higher than the predetermined value, and increases every time when it is determined that the fuel injection amount is larger than a predetermined injection amount. An oil mixed fuel amount estimated value calculating means for calculating an oil mixed fuel amount estimated value, wherein the oil mixed fuel evaporation determining means has the oil mixed fuel amount estimated value larger than a predetermined value and the engine when the load is less than a predetermined load, the internal combustion engine according to claim 1, wherein the determining and the region affected is greater evaporation of the oil in the fuel that is mixed in the crankcase Control device.

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