JP7271901B2 - engine controller - Google Patents

Description

The present invention relates to an engine control apparatus that calculates an intake air amount of an engine, determines a fuel injection amount based on the calculated value of the intake air amount, and controls fuel injection of an injector.

In order to appropriately control the air-fuel ratio (mass ratio of fuel to air) of the air-fuel mixture combusted in the cylinder, it is necessary to accurately grasp the intake air amount of the engine, that is, the mass of the intake air flowing into the cylinder. Conventionally, there are three known methods for calculating the amount of intake air: a mass flow method, a speed density method, and a throttle speed method. In the mass flow method, the amount of intake air is calculated from the amount of intake air detected by an air flow meter installed in the intake passage upstream of the throttle valve. In the speed density method, the intake pipe pressure is detected by an intake pipe pressure sensor installed downstream of the throttle valve in the intake passage. Calculate quantity. Further, in the throttle speed method, the intake air amount is calculated from the intake air flow rate estimated based on the throttle opening and the engine speed.

Normally, among these three calculation methods, the mass flow method can calculate the intake air amount during steady engine operation with the highest accuracy. However, since each cylinder of the engine intermittently draws in air according to the opening and closing of the intake valve, the flow of the intake air in the intake passage is accompanied by pulsation. Since the influence of intake pulsation also appears in the airflow meter detection value, the speed density method and throttle speed method can calculate the intake air amount with higher accuracy than the mass flow method in the operating range of the engine where the intake pulsation is large. Sometimes. Conventionally, as seen in Patent Document 1, when the intake pulsation is small, the intake air amount is calculated by the mass flow method, and when the intake pulsation is large, the intake air amount is calculated by the speed density method or the throttle speed method. An engine control device has been proposed that calculates the intake air amount while switching the calculation method according to the magnitude of the intake pulsation.

JP 2013-221418 A

In the speed density method and the throttle speed method, since the intake air amount is calculated from the estimated intake air flow rate, if there is an error in the estimation of the intake air flow rate, the calculated value will also have an error. In the above-described conventional engine control system, if such an error occurs when intake pulsation becomes large, the air-fuel ratio may deviate from a target value, resulting in deterioration of exhaust performance of the engine.

An engine control device for solving the above problems is an engine control device that calculates an intake air amount of an engine, determines a fuel injection amount based on the calculated value of the intake air amount, and controls fuel injection of an injector. a first intake air amount calculation process for calculating the intake air amount based on the detected value of the flow rate; and the difference obtained by subtracting the minimum value from the maximum detected value of the inspiratory flow rate in a specified period is divided by the average value of the detected inspiratory flow rate in the specified period If the quotient is a pulsation rate, and a state in which the value of the pulsation rate is equal to or greater than a predetermined pulsation determination value is defined as a state in which the intake air pulsation in the intake passage of the engine is large, whether or not the intake air pulsation is large. a pulsation determination process for determining whether the shift correction amount and one or more state variables selected from engine speed, intake pipe pressure, atmospheric pressure, intake air temperature, and engine water temperature are predetermined; Using the calculation map, the shift correction amount calculation process for calculating the shift correction amount from the state quantity and the calculation value of the intake air amount by the first intake air amount calculation process are set as the first intake air amount, and the first intake air amount is calculated. Assuming that the calculated value of the intake air amount in the second intake air amount calculation process is the second intake air amount, the second intake air amount with respect to the first intake air amount is calculated when it is determined in the pulsation determination process that the intake pulsation is not large. a learning process for updating the value of the deviation amount learning value so as to approach a value obtained by subtracting the shift correction amount from the difference in intake air; A first intake air amount is set as a calculated value of the intake air amount, and when it is determined in the pulsation determining process that the intake pulsation is large, the second intake air amount, the deviation amount learning value, and the shift correction are performed. A calculation method switching process for setting a value obtained by summing the intake air amount as a calculated value of the intake air amount, and a state in which the exhaust gas recirculation amount by the exhaust gas recirculation mechanism that recirculates part of the exhaust gas into the intake air cannot be grasped is described above. Abnormality determination processing for determining whether or not there is an abnormality in the exhaust gas recirculation mechanism when an abnormality has occurred in the exhaust gas recirculation mechanism, and processing for setting an upper limit value of the control range of the throttle opening, Throttle opening limit processing for setting the upper limit to a smaller value when it is determined that there is an abnormality in the exhaust gas recirculation mechanism in the abnormality determination process than when it is determined that there is no abnormality; and in the shift correction amount calculation process , when the recirculation amount is equal to or greater than a prescribed judgment value, the state in which the recirculation amount is equal to or greater than the judgment value is selected from among the plurality of calculation maps. The calculation map having a predetermined relationship between the amount and the shift correction amount is selected, and when the recirculation amount is less than the determination value, the recirculation amount is selected from among the plurality of calculation maps. The engine control device selects the calculation map in which the relationship between the state quantity and the shift correction amount when the shift correction amount is less than the determination value is determined in advance.

Further, an engine control device for solving the above problems is an engine control device that calculates an intake air amount of the engine, determines a fuel injection amount based on the calculated value of the intake air amount, and controls the fuel injection of the injector, and includes an air flow meter a first intake air amount calculation process for calculating an intake air amount based on the detected value of the intake air flow rate; and without using the detected value of the intake air flow rate, the A second intake air amount calculation process for calculating an intake air amount, and the difference obtained by subtracting the minimum value from the maximum value of the detected intake air flow rate during a specified period is the average value of the detected intake flow rates during the specified period. The divided quotient is defined as a pulsation rate, and when a state in which the value of the pulsation rate is equal to or greater than a predetermined pulsation determination value is defined as a state in which the intake air pulsation in the intake passage of the engine is large, the intake air pulsation is large. A pulsation determination process for determining whether the A shift correction amount calculation process for calculating the shift correction amount from the state quantity using a plurality of calculation maps, and a calculated value of the intake air amount by the first intake air amount calculation process is set as a first intake air amount, When the calculated value of the intake air amount obtained by the second intake air amount calculation process is the second intake air amount, when it is determined in the pulsation determination process that the intake pulsation is not large, the above-mentioned a learning process for updating the value of the deviation amount learning value so as to approach a value obtained by subtracting the shift correction amount from the difference in the second intake air amount; Sometimes, the first intake air amount is set as a calculated value of the intake air amount, and when it is determined in the pulsation determination process that the intake pulsation is large, the second intake air amount, the deviation amount learned value, and the The calculation method switching process for setting the sum of the shift correction amounts as the calculation value for the intake air amount, and the state in which the valve timing advance amount by the variable valve mechanism that makes the valve timing of the intake valve variable cannot be grasped is described above. an abnormality determination process for determining whether or not there is an abnormality in the variable valve mechanism when an abnormality has occurred in the variable valve mechanism; and a process for setting an upper limit value of the control range of the throttle opening, throttle opening limit processing for setting the upper limit to a smaller value when it is determined that there is an abnormality in the variable valve mechanism in the abnormality determination process than when it is determined that there is no abnormality; and in the shift correction amount calculation process , if the valve timing advance amount is equal to or greater than a prescribed judgment value, the valve timing advance amount is selected from among the plurality of calculation maps and is equal to or greater than the judgment value. selects the calculation map in which the relationship between the state quantity and the shift correction amount is predetermined, and selects one of the plurality of calculation maps when the valve timing advance amount is less than the determination value The engine control device selects from the calculation map in which the relationship between the state quantity and the shift correction amount is predetermined when the valve timing advance amount is less than the determination value.

1 is a diagram schematically showing an embodiment of an engine control device and a configuration of an engine to which it is applied; FIG. FIG. 2 is a block diagram showing the flow of processing related to control of the fuel injection amount executed by the engine control device; FIG. 2 is a block diagram showing the flow of intake calculation processing executed by the engine control device; 4 is a graph showing a calculation mode of the pulsation rate used by the engine control device in the pulsation determination process; 4 is a flow chart of a pulsation determination routine executed by the engine control device during pulsation determination processing; FIG. 2 is a block diagram showing the flow of processing related to shift correction amount calculation processing executed by the engine control device; FIG. 4 is a diagram showing how a deviation amount learning region is set in the engine control system; 4 is a flowchart of a deviation amount learning routine executed by the engine control device; 7 is a graph showing the relationship between the update amount of the deviation amount learning value calculated in the deviation amount learning routine and the deviation amount; FIG. 2 is a block diagram showing the flow of processing related to throttle opening degree control executed by the engine control device; 4 is a flowchart of a throttle opening limit routine executed by the engine control device; 4 is a graph showing a setting mode of the upper limit opening during failure used in processing of the same throttle opening limiting routine; 4 is a graph showing calculated values of the first intake air amount and the second intake air amount, and the relationship between the deviation amount thereof and the intake pipe pressure; 5 is a graph showing the relationship between the calculated values of the first intake air amount and the second intake air amount and the intake pipe pressure when exhaust gas recirculation is performed and when exhaust gas recirculation is stopped;

An embodiment of the engine control device will be described in detail below with reference to FIGS. 1 to 14. FIG.
As shown in FIG. 1, an air cleaner 12 for filtering dust and the like in intake air is provided at the most upstream portion of an intake passage 11 of an engine 10 to which the engine control system of this embodiment is applied. An air flow meter 13 for detecting the flow rate of intake air is provided in a portion of the intake passage 11 downstream of the air cleaner 12 . Further, a throttle valve 14 that is a valve for adjusting the flow rate of intake air in the intake passage 11 is provided at a portion of the intake passage 11 downstream of the airflow meter 13 . In the vicinity of the throttle valve 14, a throttle motor 15 for opening and closing the throttle valve 14 and a throttle sensor 16 for detecting the opening degree of the throttle valve 14 (throttle opening degree TA) are provided. .

A portion of the intake passage 11 downstream of the throttle valve 14 is provided with an intake manifold (hereinafter referred to as an intake manifold 17 ) which is a branch pipe for distributing intake air to each cylinder of the engine 10 . Each branch pipe of the intake manifold 17 is connected to a combustion chamber 19 of each cylinder via an intake port 18 for each cylinder. The intake port 18 of each cylinder is provided with an injector 20 for injecting fuel into the intake air flowing into the combustion chamber 19 through the intake port 18 . Further, the combustion chamber 19 of each cylinder is provided with an ignition device 21 that ignites a mixture of fuel and intake air that has flowed into the cylinder by electric discharge. Each cylinder is provided with an intake valve 23 and an exhaust valve 24 that open and close in conjunction with rotation of a crankshaft 22 that is an output shaft of the engine 10 . When the intake valve 23 is opened, intake air flows into the combustion chamber 19 from the intake port 18 , and when the exhaust valve 24 is opened, the exhaust gas is discharged from the combustion chamber 19 .

The engine 10 is also provided with an exhaust gas recirculation mechanism (hereinafter referred to as an EGR (Exhaust Gas Recirculation) mechanism 35) that recirculates part of the exhaust gas into intake air. The EGR mechanism 35 includes an EGR passage 32 that communicates between the exhaust passage 31 and a portion of the intake passage 11 downstream of the throttle valve 14 (for example, the intake manifold 17). In the EGR passage 32, an EGR cooler 33 for cooling the exhaust gas (EGR gas) recirculated into the intake air through the EGR passage 32, and an EGR valve 34 which is a flow control valve for adjusting the flow rate of the EGR gas. and are provided. The engine 10 is also provided with a variable valve mechanism 36 that varies the valve timing (opening/closing valve timing) of the intake valve 23 .

In such an engine 10 , the throttle valve 14 is a mechanism that directly changes the amount of intake air by adjusting the flow rate of intake air introduced into the combustion chamber 19 through the intake passage 11 . On the other hand, when the exhaust gas is recirculated by the EGR mechanism 35, even if the amount of gas flowing into the combustion chamber 19 is constant, the amount of air (intake amount) in the gas decreases by the amount of the recirculated exhaust gas. . In addition, the intake air amount also changes when the valve timing of the intake valve 23 is changed by the variable valve mechanism 36 . In this manner, the EGR mechanism 35 and the variable valve mechanism 36 are mechanisms that indirectly vary the intake air amount of the engine 10 (indirect intake variable mechanism).

The engine 10 is controlled by an electronic control unit 25 as an engine control device. The electronic control unit 25 includes an arithmetic processing circuit 41 that performs various kinds of arithmetic processing related to engine control, and a memory 42 that stores control programs and data. In addition to the airflow meter 13 and the throttle sensor 16 described above, the electronic control unit 25 includes an accelerator pedal sensor 44 that detects the amount of depression of the accelerator pedal 43 (hereinafter referred to as accelerator opening ACCP), and rotation of the crankshaft 22. A detection signal of a crank angle sensor 45 for detecting a crank angle (crank angle CRNK) is input. The electronic control unit 25 also includes an intake air temperature sensor 46 for detecting the intake air temperature THA, an atmospheric pressure sensor 47 for detecting the atmospheric pressure PA, and a water temperature sensor 48 for detecting the temperature of the cooling water of the engine 10 (engine water temperature THW). A detection signal is also input. The electronic control unit 25 controls actuators such as the throttle motor 15, the injector 20, the ignition device 21, the EGR valve 34, and the variable valve mechanism 36 based on the detection signals of these sensors, thereby performing various controls of the engine 10. It is carried out. It should be noted that the electronic control unit 25 calculates the engine speed NE from the detection result of the crank angle CRNK by the crank angle sensor 45 .

In addition, in the engine control apparatus of this embodiment, the control mode of the engine 10 can be switched between two modes, a fuel consumption mode and a power mode. Switching between these control modes is performed, for example, by operating a switch provided in the driver's seat. The fuel economy mode is a control mode that improves the fuel economy of the engine 10 by implementing a large amount of exhaust gas recirculation. On the other hand, the power mode is a control mode that increases the maximum output of the engine 10 by reducing the amount of exhaust gas recirculation compared to the fuel consumption mode and increasing the amount of air introduced into the combustion chamber 19 accordingly. ing.

In the power mode, the variable valve mechanism 36 is controlled so that the closing timing of the intake valve 23 is later than the intake bottom dead center during high load operation. If the closing timing of the intake valve 23 is later than the intake bottom dead center, part of the intake air introduced into the combustion chamber 19 in the period from the intake bottom dead center to the closing of the intake valve 23 flows into the intake passage 11. It is pushed back, and the intake pipe pressure PM increases accordingly. On the other hand, the EGR mechanism 35 utilizes the intake negative pressure to recirculate part of the exhaust gas into the intake air. smaller) reduces the amount of exhaust that can be recirculated during intake. Therefore, in the fuel efficiency mode in which a large amount of exhaust gas is recirculated, the closing timing of the intake valve 23 is advanced so that the closing timing of the intake valve 23 is earlier than in the power mode. Incidentally, even in the fuel economy mode, a large amount of exhaust gas recirculation and advance control of the closing timing of the intake valve 23 are performed only in a limited operating range such as a high load operating range. Note that the operating region in which a large amount of exhaust gas recirculation is performed in the fuel economy mode and the operating region in which the valve closing timing advance control of the intake valve 23 is performed in the same fuel economy mode do not completely overlap, and only one of them does not overlap. may be implemented.

(fuel injection amount control)
FIG. 2 shows the flow of processing of the electronic control unit 25 related to control of the fuel injection amount of the injector 20. As shown in FIG. When controlling the fuel injection amount, the electronic control unit 25 first performs the intake air amount calculation process P1 based on the AFM detected intake air amount GA, which is the detected value of the intake air flow rate of the air flow meter 13, the throttle opening TA, and the engine speed NE. 10 is calculated. The intake air amount calculated in the intake air amount calculation process P1 (hereinafter referred to as intake air amount calculation value MC) represents an estimated value of the mass of the air used for combustion in the combustion chamber 19 . Subsequently, in the injection amount determination process P2, the electronic control unit 25 makes the air-fuel ratio of the air-fuel mixture combusted in the combustion chamber 19 reach a target value based on the intake air amount calculation value MC calculated in the intake air amount calculation process P1. The fuel injection amount QINJ is determined as follows. Then, in the injector driving process P3, the electronic control unit 25 drives the injector 20 of each cylinder so that the fuel injection amount QINJ is injected.

FIG. 3 shows the processing flow of the electronic control unit 25 in the intake air amount calculation processing P1. The intake air amount calculation process P1 is executed through a first intake air amount calculation process P10, a second intake air amount calculation process P11, a pulsation determination process P12, a learning process P13, a shift correction amount calculation process P14, and a calculation method switching process P15. .

In the first intake air amount calculation process P10, the intake air amount is calculated based on the AFM detected intake air amount GA, which is the detected value of the intake air flow rate of the air flow meter 13, and the engine speed NE. Specifically, in the first intake air amount calculation process P10, the product (=K×GA/NE) obtained by dividing the AFM-detected intake air amount GA by the engine speed NE and multiplying the quotient by a prescribed coefficient K is calculated. It is obtained as a value of the inspiratory volume. Then, the intake air amount is calculated as a value that gradually changes while following the intake air amount during steady operation. That is, in the first intake air amount calculation process P10, the intake air amount is calculated by a so-called mass flow method using the detected value of the intake air flow rate of the airflow meter 13 . In the following description, the value of the intake air amount calculated by the first intake air amount calculation process P10 is referred to as the first intake air amount MC1.

In the second intake air amount calculation process P11, the intake air amount is calculated based on the throttle opening TA and the engine speed NE. Specifically, in the second intake air amount calculation process P11, the intake air flow rate is estimated based on the throttle opening TA and the engine speed NE, and the estimated value of the intake air flow rate (estimated intake air flow rate GA*) is calculated as the engine speed. The product (=K×GA*/NE) obtained by multiplying the quotient divided by NE by the coefficient K is obtained as the value of the intake air amount during steady operation. Then, the intake air amount is calculated as a value that gradually changes while following the intake air amount during steady operation. That is, in the second intake air amount calculation process P11, instead of the detected value of the intake air flow rate of the air flow meter 13, an estimated value of the intake air flow rate based on the throttle opening TA and the engine speed NE is used. Quantity calculations are performed. In the following description, the calculated value of the intake air amount obtained by the second intake air amount calculation process P11 is referred to as a second intake air amount MC2.

In the pulsation determination process P12, it is determined whether or not the intake pulsation in the intake passage 11 is large. Further, in the learning process P13, learning of a deviation amount learning value DEV[i], which is a learning value of the deviation amount of the second intake air amount MC2 with respect to the first intake air amount MC1, is performed. Further, in the shift correction amount calculation process P14, the deviation amount learned value DEV[i] in the learning process P13 is updated, and the shift correction amount SFT used for calculation of the corrected second intake air amount MC3, which will be described later, is calculated. Details of the pulsation determination process P12, the learning process P13, and the shift correction amount calculation process P14 will be described later.

In the calculation method switching process P15, the intake air amount calculation value MC is set. The mode of setting the intake air amount calculated value MC here is switched according to the determination result of the pulsation determination process P12. Specifically, when it is determined in the pulsation determination process P12 that the intake air pulsation is not large (hereinafter referred to as when the pulsation is small), the first intake air amount MC1 is determined by the first intake air amount calculation process P10. The calculated value is set as it is as the intake air amount calculated value MC. On the other hand, when it is determined in the pulsation determination process P12 that the intake air pulsation is large (hereinafter referred to as "large pulsation determination"), the second intake air amount MC2, the deviation amount learning value DEV[i ] and the shift correction amount SFT, which is the corrected second intake air amount MC3 (=MC2+DEV[i]+SFT), is set as the calculated intake air amount MC.

(Pulsation determination processing)
Next, details of the pulsation determination process P12 will be described. For determination in the pulsation determination process P12, the maximum value GMAX, minimum value GMIN, and average value GAVE of the AFM-detected intake air amount GA in the prescribed period T, as shown in FIG. 4, are used. Note that the period T is set to be longer than the cycle of the intake pulsation.

FIG. 5 shows a flowchart of a pulsation determination routine executed in the pulsation determination process P12. The process of this routine is repeatedly executed by the electronic control unit 25 at each calculation period of the intake air amount while the engine 10 is running.

When the processing of this routine is started, first, in step S100, the pulsation rate RTE is calculated. The value of the pulsation rate RTE is calculated as the quotient (=(GMAX-GMIN)/GAVE) obtained by dividing the difference obtained by subtracting the minimum value GMIN from the maximum value GMAX of the AFM-detected intake air amount GA described above by the average value GAVE. Subsequently, in step S110, it is determined whether or not the value of the pulsation rate RTE is equal to or greater than a prescribed large pulsation determination value α.

If the value of the pulsation rate RTE is equal to or greater than the pulsation determination value α (S110: YES), the process proceeds to step S120, where the large pulsation flag F is set. Furthermore, in this case, after the value of the counter COUNT is reset to 0 in step S130, the processing of this routine is terminated. The large pulsation flag F is a flag indicating the determination result of the pulsation determination process P12. Specifically, the large pulsation flag F is set when the pulsation is determined to be large, and is cleared when the pulsation is determined to be small. In the learning process P13 and the calculation method switching process P15 described above, the determination result of the pulsation determination process P12 is confirmed by whether or not the large pulsation flag F is set.

On the other hand, when the value of the pulsation rate RTE is less than the large pulsation determination value α (S110: NO), the process proceeds to step S140. Then, in step S140, it is determined whether or not the large pulsation flag F is set. Here, if the large pulsation flag F is not set (S140: NO), the process proceeds to the above-described step S130. Processing is terminated. On the other hand, if the large pulsation flag F is set (S140: YES), the process proceeds to step S150.

When the process proceeds to step S150, the value of the counter COUNT is incremented in step S150. Then, in subsequent step S160, it is determined whether or not the incremented value of the counter COUNT is greater than or equal to the prescribed pulsation OFF determination value β. If the value of the counter COUNT at this time is less than the pulsation OFF determination value β (S160: NO), the processing of this routine ends as it is. On the other hand, if the value of the counter COUNT is greater than or equal to the pulsation off determination value β (S160: YES), the large pulsation flag F is cleared in step S170, and the processing of this routine ends.

In the pulsation determination routine described above, the large pulsation flag F is set from a cleared state when the value of the pulsation rate RTE increases from a value less than the large pulsation determination value α to a value equal to or greater than the large pulsation determination value α. state. The large pulsation flag F is switched from being set to being cleared when the pulsation rate RTE is less than the large pulsation judgment value α and the value of the counter COUNT is equal to or greater than the pulsation judgment value β. On the other hand, the value of the counter COUNT is incremented when the pulsation rate RTE is less than the large pulsation judgment value α and the large pulsation flag F is set, and is reset to 0 otherwise. . That is, the increment of the value of the counter COUNT is started when the pulsation rate RTE decreases from a value equal to or greater than the large pulsation judgment value α to a value less than the large pulsation judgment value α. This is continued until either the above is reached or the large pulsation flag F is cleared. At this time, the value of the counter COUNT is incremented each time the pulsation determination routine is executed, and the pulsation determination routine is executed each cycle of calculation of the intake air amount. Therefore, when the large pulsation flag F is switched from being set to being cleared, the pulsation rate RTE decreases from a value equal to or greater than the large pulsation determination value α to a value less than the large pulsation determination value α, and after that, the pulsation rate RTE becomes This is done when the value less than the value α continues for a certain period of time.

(Shift correction amount calculation processing)
Next, the details of the shift correction amount calculation process P14 will be described.
FIG. 6 shows the flow of the shift correction amount calculation process P14. As shown in the figure, in this embodiment, four calculation maps M20 to M23 are prepared as calculation maps for the shift correction amount SFT. Each of the calculation maps M20 to M23 stores in advance the relationship between each state quantity of the engine speed NE, the intake pipe pressure PM, the atmospheric pressure PA, the intake air temperature THA, and the engine water temperature THW and the shift correction amount SFT. . In the shift correction amount calculation process P14, a calculation map to be used for calculation of the present shift correction amount SFT is selected from the calculation maps M20 to M23 according to the intake valve advance flag VVTAD and the large EGR execution flag EGREX. Using the selected calculation map, the value of the shift correction amount SFT is calculated from the engine speed NE, the intake pipe pressure PM, the atmospheric pressure PA, the intake air temperature THA, and the engine coolant temperature THW.

The intake valve advance flag VVTAD is turned ON when the valve timing advance amount of the intake valve 23 is greater than or equal to the specified advance judgment value, and is turned OFF when it is less than the advance judgment value. is a flag that The value of the valve timing advance amount is the valve closing timing (crank angle) of the intake valve 23 when the valve timing of the intake valve 23 is the slowest timing of the changeable range by the variable valve mechanism 36, which is the most retarded timing. , represents the difference between the current closing timing (crank angle) of the intake valve 23 and the most retarded timing. The intake valve advance flag VVTAD is turned on when advance control of the closing timing of the intake valve 23 is being performed in the fuel efficiency mode. On the other hand, the large EGR execution flag EGREX is turned on (ON) when the amount of exhaust gas recirculated by the EGR mechanism 35 (hereinafter referred to as the EGR amount) is equal to or greater than the specified large EGR judgment value, and is less than the large EGR judgment value. This flag is turned off when Such a large amount of EGR implementation flag EGREX is turned on when a large amount of exhaust gas recirculation is being implemented in the fuel efficiency mode. Note that the calculation map M20 is calculated when the intake valve advance flag VVTAD and the large EGR implementation flag EGREX are both ON, and the calculation map M21 is calculated when the intake valve advance flag VVTAD is ON and the large EGR implementation flag EGREX is OFF. The map M22 is for when the intake valve advance flag VVTAD is off and the large EGR execution flag EGREX is on, and the calculation map M23 is for when both the intake valve advance flag VVTAD and the large EGR execution flag EGREX are off. This map is used to calculate the shift correction amount SFT.

Here, the fuselage of the engine 10 having average intake characteristics is assumed to be the standard fuselage. The value of the deviation amount DEV under each operating state and each environmental condition in the standard aircraft can be obtained in advance. For example, the value of the deviation amount DEV is measured for each operating state and each environmental condition in a plurality of aircraft. By averaging the measured values of the deviation amount DEV for each operating state and environmental condition of each aircraft, the deviation amount DEV for each operating state and environmental condition of the standard aircraft can be obtained.

Each calculation map is created based on the measurement results of the deviation amount DEV in such a standard aircraft. That is, in the calculation map M20, the engine speed NE, the intake pipe pressure PM, the atmospheric pressure PA, the intake air temperature THA, and the engine water temperature in the standard aircraft in which both the intake valve advance flag VVTAD and the large EGR execution flag EGREX are ON. The relationship between THW and deviation amount DEV is stored in advance. Similarly, the calculation map M21 indicates that the intake valve advance flag VVTAD is on and the large amount of EGR implementation flag EGREX is off, and the calculation map M21 indicates that the intake valve advance flag VVTAD is on and the large amount of EGR implementation flag EGREX is off. The state calculation map M22 stores the above relationship in each state in which the intake valve advance flag VVTAD is off and the large amount of EGR implementation flag EGREX is on.

(learning process)
Next, the details of the learning process P13 will be described.
In the engine control apparatus of the present embodiment, deviation amount learning, which is a learning value of the deviation amount of the second intake air amount MC2 with respect to the first intake air amount MC1, is performed for each of a plurality of deviation amount learning regions divided according to the engine speed NE. value learning. The learning of the deviation amount learning value is performed by setting the value of the deviation amount learning value in the deviation amount learning region in which the engine 10 is currently operating (hereinafter referred to as the current learning region) to the first intake air amount MC1 at the time of the small pulsation determination. This is done by updating according to the amount of deviation of the intake air amount MC2. The learning of the deviation amount learning value in the engine control system of the present embodiment will be described in detail below.

FIG. 7 shows an example of how the deviation amount learning area is set. As shown in the figure, in the present embodiment, a plurality of (five in the example of the figure) deviation amount learning regions are set, which are divided by the engine speed NE. A line L in the figure indicates the maximum value of the intake pipe pressure for each engine speed in the operating range of the engine 10 . The hatched pulsation region in the figure indicates the operating region of the engine 10 in which intake pulsation large enough to reduce the detection accuracy of the airflow meter 13 occurs. The pulsation region is limited to the operating region where the intake manifold pressure is high.

In the following description, the five deviation amount learning areas are arranged in order from the smaller engine speed NE: deviation amount learning area R[1], deviation amount learning area R[2], deviation amount learning area R[3], A deviation amount learning area R[4] and a deviation amount learning area R[5] are respectively described. Also, the learned value of the deviation amount DEV in the deviation amount learning region R[i] when "i" is any one of 1, 2, 3, 4, and 5 is described as the deviation amount learned value DEV[i].

FIG. 8 shows a flowchart of a deviation amount learning routine for learning the deviation amount learning value. The process of this routine is repeatedly executed by the electronic control unit 25 at each calculation period of the intake air amount while the engine 10 is running.

When the processing of this routine is started, first, in step S200, it is determined whether or not the learning execution condition is established. Then, if the learning execution condition is not satisfied (NO), the processing of this routine ends as it is. In this embodiment, (1) warm-up of the engine 10 is completed, (2) it is not a transitional time when the operating conditions of the engine 10 change significantly, and (3) there is no abnormality in the sensor or actuator system. It is a requirement for the learning execution condition to be satisfied that all of the above are satisfied.

If the learning execution condition is satisfied (S200: YES), the process proceeds to step S210, and in step S210, it is determined whether or not the pulsation is determined to be small. Specifically, the determination here is made based on the large pulsation flag F. That is, when the large pulsation flag F is cleared, it is determined that the pulsation is determined to be small, and when the pulsation large flag F is set, it is determined that the pulsation is not determined to be small (ie, the pulsation is determined to be large). be. If the pulsation is determined to be small (YES), the process proceeds to step S220, and if the pulsation is not determined to be small (NO), that is, if the pulsation is determined to be large, the processing of this routine ends.

When the process proceeds to step S220, the deviation amount DI is calculated in step S220. Specifically, the difference ΔMC (=MC1−MC2) between the second intake air amount MC2 and the first intake air amount MC1 is subtracted from the sum of the deviation learning value DEV[i] and the shift correction amount SFT in the current speed range. (=ΔMC-DEV[i]-SFT) is calculated as the value of the deviation amount DI.

Subsequently, in step S230, it is determined whether learning of the deviation amount learned value DEV[i] in the current learning region is incomplete. Here, if learning of the deviation amount learning value DEV[i] of the current learning region has not been completed (YES), the process proceeds to step S240, and if completed (NO), the process proceeds to step S270. be advanced.

If the learning of the current learning region is incomplete and the process proceeds to step S240, it is determined in step S240 whether or not the absolute value of the deviation amount DI exceeds the specified convergence determination value ε. Here, when the absolute value of the deviation amount DI exceeds the convergence determination value ε (S240: YES), the process proceeds to step S250. On the other hand, when the absolute value of the deviation amount DI is equal to or less than the convergence judgment value ε (S240: NO), the process proceeds to step S260. After recording, the processing of this routine is terminated.

When the process proceeds to step S250, in step S250, the value of the deviation amount learning value DEV[i] of the current learning area is updated according to the deviation amount DI, and then the process of this routine ends. be done. At this time, the deviation amount learning value DEV[i] is updated so that the sum of the value before update and the update amount ΔDEV set according to the deviation amount DI becomes the value after update.

FIG. 9 shows the relationship between the deviation amount DI and the update amount ΔDEV of the deviation amount learning value DEV[i]. As shown in the figure, the value of the update amount ΔDEV is set to 0 in the range where the absolute value of the deviation amount DI is equal to or less than the convergence determination value ε. On the other hand, in the range where the absolute value of the deviation amount DI is equal to or greater than the convergence judgment value ε, the deviation amount DI is the same in positive and negative, the absolute value is smaller than the absolute value of the deviation amount DI, and the deviation amount DI When the absolute value of DEV is large, the value of the update amount ΔDEV is set so that the absolute value is larger than when the absolute value of the same deviation amount DI is small.

On the other hand, if the learning of the current learning region has been completed (S230: NO) and the process proceeds to step S270, then in step S270 the absolute value of the deviation amount DI is greater than or equal to the prescribed divergence judgment value ζ. value. A value larger than the convergence determination value ε is set to the divergence determination value ζ. Here, if the absolute value of the deviation amount DI is less than the divergence determination value ζ (NO), the processing of this routine ends as it is. On the other hand, if the absolute value of the deviation amount DI is greater than or equal to the divergence determination value ζ (YES), the process proceeds to step S280. Then, in step S280, the learning status of the current learning region is returned from completed to incomplete, and then the deviation amount learned value DEV[i] is updated in step S250.

(Throttle opening control)
Next, throttle opening control performed by the electronic control unit 25 as part of engine control will be described. The electronic control unit 25 adjusts the output of the engine 10 by changing the intake air amount through throttle opening control.

FIG. 10 shows the processing flow of the electronic control unit 25 relating to the throttle opening degree control.
The electronic control unit 25 diagnoses the engine 10 for abnormality while the engine 10 is running. The abnormality diagnosis of the engine 10 is performed by determining the presence/absence of abnormality in each sensor and each mechanism used for engine control in the abnormality determination process P40. The sensors for determining the presence or absence of an abnormality in the abnormality determination process P40 include the state variables (the intake air temperature THA, the atmospheric pressure PA, and the engine water temperature THW), an atmospheric pressure sensor 47, and a water temperature sensor 48 are included. Mechanisms for determining whether or not there is an abnormality in the abnormality determination process P40 include the EGR mechanism 35 and the variable valve mechanism 36 . As described above, the control states of these EGR mechanism 35 and variable valve mechanism 36 are used to calculate the shift correction amount SFT.

In the engine control system of the present embodiment, the throttle opening control is performed with reference to the determination result of the presence or absence of abnormality in the abnormality determination process P40. The throttle opening control is performed through a required opening calculation process P30, a throttle opening limit process P31, and a valve driving process P32.

In the required opening degree calculation process P30, a required opening degree TA*, which is a required value of the throttle opening degree TA, is calculated based on the engine speed NE and the accelerator opening degree ACCP. The calculation of the required opening degree TA* here is performed in the following procedure. That is, when calculating the required opening degree TA*, first, the required torque, which is the required value of the engine torque, is obtained from the accelerator opening degree ACCP. Subsequently, from the required torque and the engine speed NE, the load factor of the engine 10 required to generate the engine torque corresponding to the required torque is obtained as the value of the required load factor. Then, the throttle opening degree TA required to obtain the load factor for the required load factor is calculated as the value of the required opening degree TA*.

In the throttle opening limit processing P31, a value subjected to upper limit guard processing according to the result of the abnormality determination in the abnormality determination processing P40 is calculated as the value of the target opening TAT. Then, in the valve driving process P32, drive control of the throttle motor 15 is performed so that the throttle opening degree TA becomes the target opening degree TAT.

FIG. 11 shows a flowchart of a throttle opening limit routine executed by the electronic control unit 25 in the throttle opening limit processing P31. When this routine is started, first, in step S300, the required opening calculated in the required opening calculating process P30 is read. Furthermore, in steps S310 to S350, the following determinations are made. In step S310, it is determined whether or not the intake air temperature sensor 46 has been determined to be abnormal in the abnormality determination process P40. In step S320, it is determined whether or not the atmospheric pressure sensor 47 has been determined to be abnormal in the abnormality determination process P40. In step S330, it is determined whether or not the water temperature sensor 48 has been determined to be abnormal in the abnormality determination process P40. In step S340, it is determined whether or not the EGR mechanism 35 has been determined to be abnormal in the abnormality determination process P40. Then, in step S350, it is determined whether or not it is determined in the abnormality determination process P40 that the variable valve mechanism 36 has an abnormality.

Here, if a negative determination (NO) is made in any of steps S310 to S350, that is, in the abnormality determination process P40, the intake air temperature sensor 46, the atmospheric pressure sensor 47, the water temperature sensor 48, the EGR mechanism 35, and the variable valve If none of the mechanisms 36 have been determined to be abnormal, the process proceeds to step S360. Then, in step S360, the value of the required opening degree TA* is set as it is as the value of the target opening degree TAT, and then the processing of this routine ends.

On the other hand, if an affirmative determination (YES) is made in any of steps S310 to S350, that is, in the abnormality determination process P40, the intake air temperature sensor 46, the atmospheric pressure sensor 47, the water temperature sensor 48, the EGR mechanism 35, and the If it is determined that at least one of the variable valve mechanisms 36 is abnormal, the process proceeds to step S370. Then, in step S370, after the smaller value of the required opening degree TA* and the prescribed upper limit opening degree TAF during failure is set as the value of the target opening degree TAT, the processing of this routine is started. is terminated.

FIG. 12 shows a setting mode of the upper limit opening TAF during failure. The hatched pulsation opening region in FIG. 2 indicates the range of throttle opening TA in which intake pulsation large enough to reduce the detection accuracy of the airflow meter 13 occurs for each engine speed NE. Further, the maximum opening degree TAMAX shown in the figure indicates the maximum value of the throttle opening degree TA that can be set as the required opening degree TA*. Therefore, when none of the intake air temperature sensor 46, the atmospheric pressure sensor 47, the water temperature sensor 48, the EGR mechanism 35, and the variable valve mechanism 36 is determined to be abnormal, the upper limit of the control range of the throttle opening TA is The maximum opening is TAMAX.

On the other hand, the upper limit opening degree TAF at the time of failure is set to be smaller than the minimum value of the pulsation opening region, in other words, the upper limit value of the throttle opening degree TA at which the intake pulsation does not become large. there is Therefore, when it is determined that any one of the intake air temperature sensor 46, the atmospheric pressure sensor 47, the water temperature sensor 48, the EGR mechanism 35, and the variable valve mechanism 36 is abnormal, the upper limit at failure time smaller than the maximum opening TAMAX The opening degree TAF is set as the upper limit value of the control range of the throttle opening degree TA. As a result, the control range of the throttle opening TA is limited to a range in which intake pulsation does not increase.

(Action and effect of the present embodiment)
In the engine control system of this embodiment described above, in the first intake air amount calculation process P10, the intake air amount (first intake air amount MC1 ) is calculated. In addition, in the engine control apparatus of the present embodiment, in the second intake air amount calculation process P11, the intake air amount (second intake air amount MC2) is calculated by the throttle speed method based on the throttle opening degree TA without using the AFM detected intake air amount GA. is calculated.

In the intake passage 11 of the engine 10, intermittent opening of the intake valve 23 causes pulsation of intake air. When the engine 10 is operated under a high load or the like, such intake pulsation increases and the detection accuracy of the air flow meter 13 may decrease. When the detection accuracy of the airflow meter 13 decreases, the calculation accuracy of the intake air amount (first intake air amount MC1) by the mass flow method using the detection value of the airflow meter 13 also decreases. In contrast, in the present embodiment, it is determined in the pulsation determination process P12 whether or not the intake pulsation is large. When the pulsation is determined to be small, the intake air amount is calculated by the mass flow method. When the pulsation is determined to be large, the intake air amount calculation method is switched from the mass flow method to the throttle speed method.

It should be noted that the calculation of the intake air amount by the throttle speed method is less accurate than the mass flow method using the result of the actual measurement of the intake air flow rate. Assuming that the first intake air amount MC1 is accurately calculated at the time of the small pulsation determination, the deviation of the second intake air amount MC2 from the first intake air amount MC1 at this time corresponds to the error in the calculated value of the second intake air amount MC2. . Therefore, in the present embodiment, in the learning process P13, the deviation of the second intake air amount MC2 from the first intake air amount MC1 at the time of the small pulsation determination is learned as the deviation amount learned value DEV[i]. By reflecting the learning result in the calculation of the intake air amount in the throttle speed method when the large pulsation is determined, the calculation accuracy of the intake air amount when the large pulsation is determined is ensured.

FIG. 13 shows the first intake air amount MC1 and the second intake air amount MC1 and the second 3 shows the calculated value of the intake air amount MC2 and the relationship between the deviation amount DEV and the intake pipe pressure PM. As shown in the figure, even if there is no change in the control state of the engine 10 other than the intake pipe pressure PM, if the intake pipe pressure PM changes, the deviation amount DEV will have a different value. Further, the engine speed NE is also a factor that changes the deviation amount DEV, like the intake pipe pressure PM.

In FIG. 14, the engine speed NE and the valve timing of the intake valve 23 are fixed when the EGR valve 34 is fully open (when EGR is on) and when the EGR valve 34 is fully closed (when EGR is off). The relationship between the intake pipe pressure PM and the calculated values of the first intake air amount MC1 and the second intake air amount MC2 when the intake pipe pressure PM is changed according to the state is shown. As shown in the figure, the deviation amount DEV also changes depending on whether or not a large amount of exhaust gas recirculation is performed.

In addition, the deviation amount DEV changes depending on whether or not advance control of the closing timing of the intake valve 23 is performed. Therefore, in the engine 10, in addition to the engine speed NE and the intake pipe pressure PM, the control states of the EGR mechanism 35 and the variable valve mechanism 36 are factors that determine the deviation amount DEV.

In addition to these factors, the environmental conditions under which the engine 10 is operated are also factors that change the deviation amount DEV. For example, when the atmospheric pressure PA is high, the intake air amount increases even if the engine speed NE and the throttle opening TA are the same. A change in the amount of intake air due to the atmospheric pressure PA appears in the detection value of the intake flow rate of the air flow meter 13 . Therefore, the influence of the atmospheric pressure PA on the intake air amount is accurately reflected to some extent in the first intake air amount MC1 calculated by the mass flow method using the intake air flow rate detected by the air flow meter 13 . On the other hand, the second intake air amount MC2 calculated by the throttle speed method using the estimated value of the intake air flow rate based on the throttle opening TA and the engine speed NE is not reflected as accurately as the first intake air amount MC1. It will be.

In addition, the intake air temperature THA and the engine water temperature THW are also factors that change the deviation amount DEV. As the intake air temperature THA increases, the intake air density decreases. On the other hand, when the engine water temperature THW is high and the wall surface temperature of the intake port 18 and the combustion chamber 19 is high, the temperature of the intake air flowing into the combustion chamber 19 increases due to the heat received from these wall surfaces. As the temperature of the intake air flowing into the combustion chamber 19 increases, the density of the intake air decreases. Therefore, even if the volumetric flow rate of the intake air passing through the throttle valve 14 is the same, the amount of intake air (the mass of the intake air flowing into the combustion chamber 19) decreases. When the amount of intake air changes due to such a change in the density of intake air, the flow rate of intake air detected by the air flow meter 13 also changes. On the other hand, the estimation result of the intake air flow rate based on the throttle opening TA and the engine speed NE in the throttle speed method does not reflect the influence of such a change in intake air density due to temperature. Therefore, the deviation amount DEV also changes depending on the intake air temperature THA and the engine water temperature THW.

As described above, the deviation amount DEV changes depending on the operating state of the engine 10 and environmental conditions. The effects of the operating state and environmental conditions of the engine 10 on the deviation amount DEV can be confirmed in advance by experiments or the like. On the other hand, the deviation amount DEV also changes due to individual differences in the intake characteristics of the engine 10 and changes over time, but changes due to such individual differences and changes over time cannot be confirmed in advance.

In the engine control system of the present embodiment, the operating state of the engine 10 (the engine speed NE, the intake pipe pressure PM, the control state of the exhaust gas recirculation mechanism and the variable valve mechanism 36) and the state quantity of the environmental conditions (atmospheric pressure PA , intake air temperature THA, and engine water temperature THW) is calculated as the shift correction amount SFT. Then, the difference obtained by subtracting the shift correction amount SFT from the deviation of the second intake air amount MC2 with respect to the first intake air amount MC1 when the pulsation is judged to be small is learned as the deviation amount learning value DEV[i]. Therefore, the deviation amount learned value DEV[i] is a value obtained by excluding changes due to the operating state and environmental conditions of the engine 10 from the deviation between the first intake air amount MC1 and the second intake air amount MC2. The amount of change in the above-mentioned deviation due to individual differences in intake characteristics and changes over time is learned. Then, the sum obtained by adding the shift correction amount SFT to the deviation amount learning value DEV[i] is calculated as the value of the deviation amount DEV, and the sum of adding the deviation amount DEV to the second intake air amount MC2 is calculated when large pulsation is determined. is obtained as the value of the corrected second intake air amount MC3 which is set as the calculated intake air amount MC. Therefore, even if the operating state and environmental conditions of the engine 10 are different when learning the deviation amount learning value DEV[i] and when reflecting the same deviation amount learning value DEV[i] to the intake air amount calculation value MC, the pulsation It is possible to appropriately calculate the intake air amount at the time of large determination. As a result, it becomes possible to expand the range of operating states and environmental conditions of the engine 10 in which the learning of the deviation amount learning value DEV[i] is carried out. It is possible to shorten the time required for

If an abnormality occurs in the intake air temperature sensor 46, atmospheric pressure sensor 47, or water temperature sensor 48, and the atmospheric pressure PA, intake air temperature THA, or engine water temperature THW cannot be properly detected, the shift correction amount SFT cannot be properly calculated. Gone. In addition, even if an abnormality occurs in the EGR mechanism 35 or the variable valve mechanism 36 and the control state thereof (EGR amount or valve timing advance amount) cannot be grasped, the shift correction amount SFT can be appropriately calculated. Gone. Therefore, when these abnormalities occur, learning of the deviation amount learning value DEV[i] at the time of small pulsation determination, and reflection of the deviation amount learning value DEV[i] to the intake air amount calculation value MC at the time of large pulsation determination cannot be performed accurately. That is, when the intake air pulsation increases, an inaccurate shift correction amount SFT is reflected in the intake air amount calculation value MC. There is a risk that the control accuracy of the fuel ratio will deteriorate, leading to deterioration of the exhaust performance of the engine 10 .

In this regard, in the engine control system of the present embodiment, when such an abnormality occurs, the throttle opening TA is limited to the upper limit opening at failure time or less. The failure upper limit opening degree is set to an opening degree smaller than the upper limit value of the throttle opening degree TA at which the intake pulsation is not large. Therefore, the engine 10 is operated within a range in which the intake air pulsation does not increase, thereby preventing the intake air amount calculation value MC from being calculated based on the inaccurate shift correction amount SFT.

This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
(Regarding the setting of the deviation amount learning area)
In the above embodiment, the deviation amount learning value DEV[i] is individually learned for each of the plurality of deviation amount learning areas divided by the engine speed NE. A single deviation learning value may be learned for the entire operating range of the engine.

(Calculation of shift correction amount)
In the above-described embodiment, the calculation map for the shift correction amount SFT is switched according to the control state of the exhaust gas recirculation mechanism and the variable valve mechanism 36. However, other modes may be used. 36 may be reflected in the shift correction amount SFT. For example, the engine speed NE, the intake pipe pressure PM, the atmospheric pressure PA, the intake air temperature THA, the engine water temperature THW, the EGR amount (or the opening of the EGR valve 34), and the valve timing advance amount of the intake valve 23 are used as input values, and the shift It is also possible to calculate the shift correction amount SFT using a single calculation map that returns the correction amount SFT.

(Regarding the variable indirect intake mechanism)
In the above embodiment, two control states, ie, the control state of the exhaust gas recirculation mechanism and the control state of the variable valve mechanism, are used as the control states of the variable indirect intake mechanism used to calculate the shift correction amount SFT. When either one of the exhaust gas recirculation mechanism and the variable valve mechanism is not provided in the engine, or when either one of them is controlled in conjunction with the throttle opening TA, The control state of only one of the exhaust gas recirculation mechanism and the variable valve mechanism may be used as the control state of the indirect intake variable mechanism used to calculate the shift correction amount SFT. In addition to these, if the engine is provided with a mechanism that is controlled independently of the throttle opening TA to cause a change in the intake air amount, the control state of the mechanism may be changed to the shift correction amount SFT. It may be adopted as the control state of the variable indirect intake mechanism used for calculation. Indirect intake variable mechanisms other than the exhaust gas recirculation mechanism and the variable valve mechanism include, for example, the following.

One type of variable valve mechanism is a mechanism that varies the valve lift amount of the intake valve 23 (lift amount variable mechanism). When the variable lift mechanism is controlled without being interlocked with the throttle opening TA, the relationship between the engine speed NE, the intake pipe pressure PM, and the deviation amount DEV depends on the control state of the variable lift mechanism (intake valve 23 valve lift amount). The variable lift mechanism in such a case corresponds to an indirect variable intake mechanism, which is a mechanism provided in the engine and which is controlled in a non-interlocking manner with the throttle opening TA to change the intake air amount of the engine. In such a case, it is preferable to use the control state of the variable lift mechanism as one of the control states of the variable indirect intake mechanism that is referred to when calculating the shift correction amount SFT.

Some engines with a plurality of turbochargers are provided with a variable supercharging mechanism that changes the number of operating turbochargers. When such a supercharging mechanism is controlled without being interlocked with the throttle opening TA, the relationship between the engine speed NE, the intake pipe pressure PM, and the deviation amount DEV depends on the control state of the variable supercharging mechanism (turbocharger operating number). The variable supercharging mechanism in such a case is a mechanism provided in the engine and corresponds to an indirect intake variable mechanism that is controlled independently of the throttle opening TA to cause a change in the intake air amount of the engine. In such a case, it is preferable to use the control state of the variable supercharging mechanism as one of the control states of the variable indirect intake mechanism referred to when calculating the shift correction amount SFT.

It has two types of fuel injection valves, a port injection valve that injects fuel into the intake port 18 and an in-cylinder injection valve that injects fuel into the combustion chamber 19, and injects fuel according to the operating conditions of the engine. Some engines have an injection switching mechanism that switches fuel injection valves. In such an engine, when fuel injection is performed by an in-cylinder injection valve, the inside of the combustion chamber 19 is cooled by the heat of vaporization of the injected fuel, and the density of the intake air introduced into the combustion chamber 19 increases. The amount of intake air, ie, the mass of the intake air introduced into the combustion chamber 19, is greater than when fuel is injected only by the port injection valve. When such an injection switching mechanism is controlled without being interlocked with the throttle opening TA, the relationship between the engine speed NE, the intake pipe pressure PM, and the deviation amount DEV depends on the control state of the injection switching mechanism (fuel for fuel injection). switching of the injection valve). In such a case, the injection switching mechanism is a mechanism provided in the engine and corresponds to an indirect variable intake mechanism that is controlled in a non-interlocking manner with the throttle opening TA to change the intake air amount of the engine. In such a case, it is preferable to use the control state of the injection switching mechanism as one of the control states of the variable indirect intake mechanism to be referred to when calculating the shift correction amount SFT.

Even in such a case, if it is determined that there is an abnormality in the variable indirect intake mechanism that refers to the control state when calculating the shift correction amount SFT, the upper limit value of the control range of the throttle opening TA is set to By setting the degree of opening to be smaller than when it is determined that the intake air amount is calculated with a lower degree of opening, it is possible to suppress the deterioration of the exhaust performance due to the deterioration of the calculation accuracy of the intake air amount.

(Regarding state quantities of environmental conditions)
In the above embodiment, three state quantities of the atmospheric pressure PA, the intake air temperature THA, and the engine water temperature THW are used as the state quantities of the environmental conditions to calculate the shift correction amount SFT. In addition, as the state quantity of the environmental condition of the engine 10 that causes a change in the deviation amount DEV, for example, pressure state quantities such as surge tank pressure and boost pressure in a supercharged engine, outside air temperature, engine oil temperature, intake air temperature, etc. There is a temperature state quantity such as the wall surface temperature of the port 18 . Depending on the configuration of the engine and the calculation logic of the intake air amount in the first intake air amount calculation process P10 and the second intake air amount calculation process P11, the state quantity that greatly affects the deviation amount may differ. Therefore, it is preferable to select the state quantity of the environmental condition that greatly affects the deviation amount DEV and use the selected state quantity for the calculation of the shift correction amount SFT. Even in such a case, if it is determined that there is an abnormality in the sensor that detects the state quantity used to calculate the shift correction amount SFT, the upper limit value of the control range of the throttle opening degree TA is determined to have no abnormality. By setting the degree of opening to be smaller than when it is set, it is possible to suppress the deterioration of the exhaust performance due to the deterioration of the calculation accuracy of the intake air amount.

If there is no state quantity of environmental conditions that greatly affects the deviation amount, the operating state of the engine (engine speed NE, intake pipe pressure PM, and The shift correction amount SFT may be calculated based on the control state of the variable indirect intake mechanism.

(Regarding the second intake air amount calculation process)
In the above-described embodiment, the calculation of the second intake air amount MC2 in the second intake air amount calculation process P11 is performed by a so-called throttle speed method using an estimated value of the intake air flow rate based on the throttle opening TA and the engine speed NE. . The calculation of the second intake air amount MC2 may be performed by a so-called speed density method using an estimated value of the intake air flow rate based on the detection results of the intake pipe pressure PM and the engine speed NE.

(Regarding throttle opening limit processing)
In the above-described embodiment, the target opening is set so that the upper limit of the control range of the throttle opening TA at the time of abnormality determination is lower than the upper limit at the time of failure after calculating the required opening. It was done by setting The opening of the upper limit of the control range of the throttle opening TA at the time of such an abnormality determination is performed in the required opening calculating process P30. An upper limit guard may be applied to the required opening so that the required opening is achieved.

Further, in the above-described embodiment, as the upper limit opening at the time of failure, an opening smaller than the minimum value of the pulsation opening is set. Deterioration of exhaust performance due to deterioration of calculation accuracy can be suppressed to some extent. That is, even if the control range of the throttle opening degree TA at the time of abnormality determination includes the pulsation opening region, if the upper limit value of the control range of the throttle opening degree TA is set to a smaller opening than normal, the combustion chamber The amount of intake air flowing into the combustion chamber 19 and thus the amount of air-fuel mixture burning in the combustion chamber 19 is limited. Therefore, when an inaccurate shift correction amount SFT is reflected in the calculation result of the intake air amount and the control accuracy of the air-fuel ratio deteriorates, harmful components (CO, HC, NOx etc.), the deterioration of the exhaust performance can be suppressed to some extent.

DESCRIPTION OF SYMBOLS 10... Engine, 11... Intake passage, 12... Air cleaner, 13... Air flow meter, 14... Throttle valve, 15... Throttle motor, 16... Throttle sensor, 17... Intake manifold, 18... Intake port, 19... Combustion chamber, 20... Injector 21 Spark plug 22 Crankshaft 23 Intake valve 24 Exhaust valve 25 Electronic control unit (engine control device) 26 Arithmetic processing circuit 27 Memory 31 Exhaust passage 35 Exhaust gas recirculation (EGR) mechanism (indirect variable intake mechanism) 36 Variable valve mechanism (variable indirect intake mechanism) 43 Accelerator pedal 44 Accelerator pedal sensor 45 Crank angle sensor 46 Intake air temperature sensor 47 Atmospheric pressure sensor 48 Water temperature sensor P1 Intake amount calculation process P2 Injection amount determination process P3 Injector drive process P10 First intake air amount calculation process P11 Second intake air amount calculation process P12 Pulsation determination process P13 Learning process P14 Shift correction amount calculation process P15 Calculation method switching process P30 Requested opening calculation process P31 Throttle opening limit process P32 Valve drive process P40 Abnormality Determination process.

Claims (2)

In an engine control device that calculates the intake air amount of the engine and determines the fuel injection amount based on the calculated value of the intake air amount to control the fuel injection of the injector,
a first intake air amount calculation process for calculating the intake air amount based on the detected value of the intake air flow rate of the air flow meter;
a second intake air amount calculation process for calculating the intake air amount based on either one of the intake pipe pressure and the throttle opening without using the detected value of the intake air flow rate;
The quotient obtained by dividing the difference obtained by subtracting the minimum value from the maximum detected value of the inspiratory flow rate in a specified period by the average value of the detected inspiratory flow rate in the specified period is defined as the pulsation rate, and the value of the pulsation rate. is greater than or equal to a predetermined pulsation determination value, a pulsation determination process for determining whether or not the intake pulsation in the intake passage of the engine is large;
Using a plurality of calculation maps in which the relationship between one or more state variables selected from engine speed, intake pipe pressure, atmospheric pressure, intake air temperature, and engine coolant temperature and the shift correction amount is predetermined, the state shift correction amount calculation processing for calculating the shift correction amount from the amount;
When the calculated value of the intake air amount obtained by the first intake air amount calculation process is set as the first intake air amount and the calculated value of the intake air amount obtained by the second intake air amount calculation process is set as the second intake air amount, the pulsation determination process When it is determined that the intake pulsation is not large, the deviation amount learning value is updated so as to approach a value obtained by subtracting the shift correction amount from the difference between the second intake air amount and the first intake air amount. a learning process to
When it is determined in the pulsation determination process that the intake pulsation is not large, the first intake air amount is set as the calculated value of the intake air amount, and if the intake pulsation is large in the pulsation determination process. A calculation method switching process for setting a value obtained by summing the second intake air amount, the deviation amount learning value, and the shift correction amount as a calculated value of the intake air amount when the determination is made;
Abnormality of the exhaust gas recirculation mechanism when the exhaust gas recirculation mechanism, which recirculates a part of the exhaust gas into the intake air, cannot grasp the amount of exhaust gas recirculated. Abnormality determination processing for determining the presence or absence of
In the process of setting the upper limit value of the control range of the throttle opening, when it is determined that there is no abnormality in the abnormality determination process when it is determined that there is an abnormality in the exhaust gas recirculation mechanism Throttle opening limit processing for setting a value smaller than the upper limit value,
and
In the shift correction amount calculation process, when the recirculation amount is equal to or greater than a prescribed judgment value, the state quantity and the The calculation map having a predetermined relationship with the shift correction amount is selected, and when the recirculation amount is less than the judgment value, the recirculation amount is selected from among the plurality of calculation maps to be the judgment value. An engine control device that selects the arithmetic map in which the relationship between the state quantity and the shift correction amount when the shift correction amount is less than is predetermined. In an engine control device that calculates the intake air amount of the engine and determines the fuel injection amount based on the calculated value of the intake air amount to control the fuel injection of the injector,
a first intake air amount calculation process for calculating the intake air amount based on the detected value of the intake air flow rate of the air flow meter;
a second intake air amount calculation process for calculating the intake air amount based on either one of the intake pipe pressure and the throttle opening without using the detected value of the intake air flow rate;
The quotient obtained by dividing the difference obtained by subtracting the minimum value from the maximum detected value of the inspiratory flow rate in a specified period by the average value of the detected inspiratory flow rate in the specified period is defined as the pulsation rate, and the value of the pulsation rate. is greater than or equal to a predetermined pulsation determination value, a pulsation determination process for determining whether or not the intake pulsation in the intake passage of the engine is large;
Using a plurality of calculation maps in which the relationship between one or more state variables selected from engine speed, intake pipe pressure, atmospheric pressure, intake air temperature, and engine coolant temperature and the shift correction amount is predetermined, the state shift correction amount calculation processing for calculating the shift correction amount from the amount;
When the calculated value of the intake air amount obtained by the first intake air amount calculation process is set as the first intake air amount and the calculated value of the intake air amount obtained by the second intake air amount calculation process is set as the second intake air amount, the pulsation determination process When it is determined that the intake pulsation is not large, the deviation amount learning value is updated so as to approach a value obtained by subtracting the shift correction amount from the difference between the second intake air amount and the first intake air amount. a learning process to
When it is determined in the pulsation determination process that the intake pulsation is not large, the first intake air amount is set as the calculated value of the intake air amount, and if the intake pulsation is large in the pulsation determination process. A calculation method switching process for setting a value obtained by summing the second intake air amount, the deviation amount learning value, and the shift correction amount as a calculated value of the intake air amount when the determination is made;
Presence or absence of an abnormality in the variable valve mechanism when an abnormality occurs in the variable valve mechanism when the state in which the valve timing advance amount by the variable valve mechanism that makes the valve timing of the intake valve can be varied cannot be grasped. Abnormality determination processing for determining
In the process of setting the upper limit value of the control range of the throttle opening, when it is determined that there is no abnormality in the abnormality determination process when it is determined that there is an abnormality in the variable valve mechanism Throttle opening limit processing for setting a value smaller than the upper limit value,
and
In the shift correction amount calculation process, when the valve timing advance amount is equal to or greater than a prescribed judgment value, the above-described calculation map for the case where the valve timing advance amount is equal to or larger than the judgment value is selected from among the plurality of calculation maps. The calculation map in which the relationship between the state quantity and the shift correction amount is predetermined is selected, and when the valve timing advance amount is less than the determination value, the valve timing is selected from the plurality of calculation maps. The engine control device selects the arithmetic map in which the relationship between the state quantity and the shift correction amount is predetermined when the timing advance amount is less than the determination value.

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