JP7690873B2 - Engine Control Unit - Google Patents

Description

The present invention relates to an engine control device.

The method described in Patent Document 1 is known as a method for calculating the amount of intake air flowing into the combustion chamber of an engine, which is the amount of intake air flowing into the cylinder. The calculation method described in this document calculates the amount of intake air flowing into the cylinder by inputting the detected intake pressure value into an intake valve model. The intake valve model is a physical model of the behavior of the intake air flowing from the intake passage through the intake valve into the combustion chamber.

In addition to the intake valve model, a method of calculating the amount of intake air into the cylinder from the throttle opening is also known, which uses two physical models, a throttle model and an intake pipe model, to calculate the amount of intake air into the cylinder from the throttle opening. The throttle model is a physical model that describes the behavior of the intake air passing through the throttle valve. The intake pipe model is a physical model that describes the behavior of the intake air in the portion of the intake passage downstream of the throttle valve.

JP 2015-224611 A

The above physical models do not completely reproduce the actual intake behavior. Therefore, when calculating the amount of intake air in the cylinder using the above three physical models, errors may occur due to the discrepancy between the intake behavior of the physical model and the actual intake behavior. Since many factors are involved in these errors, it is difficult to correct them.

The engine control device that solves the above problem performs a throttle flow calculation process that uses a throttle model, which is a physical model of the behavior of the intake air passing through the throttle valve, to calculate the throttle flow rate based on the throttle opening, throttle upstream pressure, and throttle downstream pressure; a throttle downstream pressure calculation process that uses an intake pipe model, which is a physical model of the behavior of the intake air flowing through the portion of the intake passage downstream of the throttle valve, to calculate the throttle downstream pressure based on the throttle flow rate and the intake air amount in the cylinder; an intake valve model, which is a physical model of the behavior of the intake air flowing from the intake passage into the combustion chamber, to calculate the intake air amount in the cylinder based on the throttle downstream pressure; a first shift correction that corrects the calculated value of the throttle flow rate by the throttle model based on a state quantity indicating the operating state of the engine; and a second shift correction that corrects the calculated value of the intake air amount in the cylinder by the intake valve model based on a state quantity indicating the operating state of the engine. Note that the in-cylinder intake volume represents the amount of intake air flowing into the combustion chamber from the engine's intake passage, the throttle opening represents the opening of the throttle valve installed in the intake passage, the throttle upstream pressure represents the pressure of the intake air before it passes through the throttle valve, the throttle downstream pressure represents the pressure of the intake air after it passes through the throttle valve, and the throttle flow rate represents the flow rate of the intake air passing through the throttle valve.

The engine control device calculates the amount of intake air into the cylinder using each of the physical models, namely, the throttle model, the intake pipe model, and the intake valve model. The calculated amount of intake air into the cylinder is used to control the engine. The physical model used to calculate the amount of intake air into the cylinder needs to be a simplified model due to limitations in the processing power of the engine control device and the time required to complete the calculation. As a result, the intake behavior in the physical model may deviate from the actual behavior in some areas, which may result in an error in the calculation result of the amount of intake air into the cylinder.

The decrease in accuracy of the calculation of the in-cylinder intake volume caused by such errors in the physical model can be reduced by the following method. First, the in-cylinder intake volume for each engine operating state is measured using an actual engine to determine the error in the physical model. Then, the calculated value of the in-cylinder intake volume using the physical model is corrected according to the error measurement results. However, to perform such corrections with high accuracy, it is necessary to actually measure the in-cylinder intake volume at a huge number of operating points.

On the other hand, if it is not intended to be used in an engine control device, there are no limitations on processing power or calculation time, making it possible to create a simulation model that reproduces the intake behavior of the engine more accurately than a physical model implemented in the engine control device. However, since numerous factors affect the intake behavior of the entire engine intake system, and the mechanisms of these effects are complex, it is not easy to create such a simulation model. In comparison, it is easy to create a simulation model that is limited to the intake behavior at the throttle valve or the intake valve.

In the above engine control device, the error of the throttle model among the errors in the calculation result of the intake amount in the cylinder by the physical model is corrected by the first shift correction. In addition, in the above engine control device, the error of the intake valve model among the errors in the calculation result of the intake amount in the cylinder by the physical model is corrected by the second shift correction. As described above, a simulation model limited to the behavior of the intake at the throttle valve and a simulation model limited to the behavior of the intake at the intake valve can be created relatively easily. Therefore, data required for highly accurate correction of the throttle model error in the first shift correction and the intake valve model error in the second shift correction can be easily collected at the design stage of the engine control device.

If the errors in the throttle model and the intake valve model can be accurately corrected, the accuracy of the calculation of the amount of intake air in the cylinder using a physical model that includes them will improve. Therefore, the engine control device described above can calculate the amount of intake air in the cylinder with high accuracy.

The engine control device is applicable to an engine equipped with a variable valve mechanism that varies the valve characteristics of the engine valve. In such a case, it is desirable that the state quantity used to correct the calculated value of the throttle flow rate by the first shift correction includes the operating amount of the variable valve mechanism. Also, in such a case, it is desirable that the state quantity used to correct the calculated value of the in-cylinder intake air amount by the second shift correction includes the operating amount of the variable valve mechanism.

The engine control device is also applicable to an engine that recirculates exhaust gas into the intake air. In such a case, it is desirable that the state quantity used to correct the calculated value of the throttle flow rate by the first shift correction process includes a state quantity indicating the amount of exhaust gas recirculated. In such a case, it is also desirable that the state quantity used to correct the calculated value of the in-cylinder intake air volume by the second shift correction process includes a state quantity indicating the amount of exhaust gas recirculated.

The engine control device described above can be applied to an engine equipped with a filter device that collects particulate matter in the exhaust. In such a case, it is desirable to include a state quantity indicating the degree of clogging of the filter device in the state quantity used to correct the calculated value of the in-cylinder intake air amount by the second shift correction process.

1 is a diagram illustrating a configuration of a first embodiment of an engine control device; FIG. 2 is a control block diagram of a process related to calculation of an in-cylinder intake amount by the engine control device; A graph showing the relationship between the pressure ratio before and after the throttle and the phi value. 5 is a graph showing the relationship between the throttle downstream pressure and the amount of intake air in a cylinder. FIG. 4 is a control block diagram of a throttle flow rate calculation process. FIG. 4 is a control block diagram of a cylinder intake air amount calculation process. 6 is a graph showing the relationship between the throttle downstream pressure and a second shift correction value.

First Embodiment
Hereinafter, a first embodiment of an engine control device will be described in detail with reference to Figures 1 to 7. First, the configuration of the engine control device of this embodiment will be described with reference to Figure 1.

<Configuration of engine control device>
As shown in FIG. 1, the engine 10 includes a combustion chamber 11 in which the mixture is burned, an intake passage 12 which is a supply passage for intake air to the combustion chamber 11, and an exhaust passage 13 which is a discharge passage for exhaust gas from the combustion chamber 11. The engine 10 also includes an injector 14 which injects fuel into the intake air introduced into the combustion chamber 11 to form an air-fuel mixture. The engine 10 also includes an ignition device 15 which ignites the air-fuel mixture in the combustion chamber 11 by spark discharge. The combustion chamber 11 is connected to the intake passage 12 via an intake valve 19 which is an engine valve on the intake side. The combustion chamber 11 is also connected to the exhaust passage 13 via an exhaust valve 21 which is an engine valve on the exhaust side. The engine 10 also includes an intake-side variable valve mechanism 20 which changes the valve characteristics of the intake valve 19, and an exhaust-side variable valve mechanism 22 which changes the valve characteristics of the exhaust valve 21. The variable valve mechanisms 20, 22 are mechanisms that vary the valve timing of, for example, the intake valve 19 or the exhaust valve 21. In the following description, the amount of operation of the intake-side variable valve mechanism 20 will be referred to as intake valve timing VTI. Also, in the following description, the amount of operation of the exhaust-side variable valve mechanism 22 will be referred to as exhaust valve timing VTE.

An air cleaner 16 and a throttle valve 17 are installed in the intake passage 12. The air cleaner 16 is a filter that filters the intake air taken into the intake passage 12. The throttle valve 17 is a valve that changes the flow area of the intake air according to changes in the opening degree. The throttle valve 17 is driven to open and close by a throttle motor 18. In the following explanation, the opening degree of the throttle valve 17 is referred to as the throttle opening degree TA. The intake passage 12 is branched for each cylinder at an intake manifold 12A, which is a branch pipe installed downstream of the throttle valve 17. On the other hand, a filter device 23 that collects particulate matter in the exhaust is installed in the exhaust passage 13.

The engine 10 is further equipped with an EGR (exhaust gas recirculation) system that recirculates a portion of the exhaust gas into the intake air. The EGR system has an EGR passage 24 that connects the exhaust passage 13 and the intake passage 12. The EGR system also has an EGR cooler 25 and an EGR valve 26. The EGR cooler 25 cools the EGR gas, which is the exhaust gas that is recirculated into the intake air through the EGR passage 24. The EGR valve 26 is a valve for adjusting the EGR amount, which is the flow rate of the EGR gas that is recirculated into the intake air.

The engine 10 is controlled by an ECM (engine control module) 30. The ECM 30 includes a processing unit 31 and a storage unit 32. The storage unit 32 stores programs and data for controlling the engine 10. The processing unit 31 executes various processes for controlling the engine 10 by executing programs read from the storage unit 32. Various sensors are connected to the ECM 30. The sensors connected to the ECM 30 include an intake air temperature sensor 33, an atmospheric pressure sensor 34, a throttle opening sensor 35, a differential pressure sensor 36, a crank angle sensor 38, and an accelerator pedal sensor 40. The intake air temperature sensor 33 is a sensor that detects the intake air temperature THA, which is the temperature of the intake air taken into the intake passage 12 from the outside. The atmospheric pressure sensor 34 is a sensor that detects the atmospheric pressure PA. The throttle opening sensor 35 is a sensor that detects the throttle opening TA. The differential pressure sensor 36 is a sensor that detects the filter differential pressure ΔP, which is the pressure difference of the exhaust gas between the upstream and downstream portions of the filter device 23 in the exhaust passage 13. The crank angle sensor 38 is a sensor that detects the crank angle CRNK, which is the rotation angle of the crankshaft 37, which is the output shaft of the engine 10. The accelerator pedal sensor 40 is a sensor that detects the amount of depression ACC of the accelerator pedal 39 by the driver.

The ECM 30 calculates the engine speed NE based on the detection result of the crank angle CRNK. The ECM 30 also calculates the in-cylinder intake air amount MC, which is the amount of intake air introduced into the combustion chamber 11, based on the calculation result of the engine speed NE and the detection results of the atmospheric pressure PA, the intake air temperature THA, the throttle opening TA, etc. The ECM 30 controls the operating state of the engine 10 based on the calculation results of the engine speed NE and the in-cylinder intake air amount MC. The operating state of the engine 10 controlled by the ECM 30 includes the fuel injection amount QINJ of the injector 14, the ignition timing SA of the ignition device 15, the throttle opening TA, the intake valve timing VTI, and the exhaust valve timing VTE.

<Calculation process of cylinder intake air amount MC>
Next, the calculation process of the in-cylinder intake air amount MC performed by the ECM 30 will be described in detail with reference to FIGS.

Figure 2 shows the processing procedure of the ECM 30 for calculating the in-cylinder intake air amount MC. The ECM 30 calculates the in-cylinder intake air amount MC through throttle upstream pressure calculation process 100, throttle flow rate calculation process 101, throttle downstream pressure calculation process 102, and in-cylinder intake air amount calculation process 103. The throttle upstream pressure calculation process 100 is a process for calculating the throttle upstream pressure PAC, which is the pressure of the intake air flowing into the throttle valve 17. The throttle flow rate calculation process 101 is a process for calculating the throttle flow rate MT, which is the flow rate of the intake air passing through the throttle valve 17. The throttle downstream pressure calculation process 102 is a process for calculating the throttle downstream pressure PM, which is the pressure of the intake air in the intake manifold 12A. The in-cylinder intake air amount calculation process 103 is a process for calculating the in-cylinder intake air amount MC, which is the amount of intake air introduced from the intake passage 12 to the combustion chamber 11.

The throttle upstream pressure PAC is calculated in the throttle upstream pressure calculation process 100 using an air cleaner model 104. The air cleaner model 104 is a physical model that represents the behavior of the intake air passing through the air cleaner 16. The throttle flow rate MT is calculated in the throttle flow rate calculation process 101 using a throttle model 105. The throttle model 105 is a physical model that represents the behavior of the intake air passing through the throttle valve 17. The throttle downstream pressure calculation process 102 uses an intake pipe model 106 to calculate the throttle downstream pressure PM. The intake pipe model 106 is a physical model that represents the behavior of the intake air flowing through the intake manifold 12A. The cylinder intake air amount calculation process 103 uses an intake valve model 107 to calculate the cylinder intake air amount MC. The intake valve model 107 is a physical model that represents the behavior of intake air flowing from the intake passage 12 into the combustion chamber 11 via the intake valve 19.

<About Air Cleaner Model 104>
First, the air cleaner model 104 will be described in detail. In the ECM 30, the air cleaner model 104 is implemented as a function that takes the intake air temperature THA, the atmospheric pressure PA, and the throttle flow rate MT as inputs and the throttle upstream pressure PAC as output. In the air cleaner model 104, the throttle flow rate MT is used as the flow rate of the intake air passing through the air cleaner 16. The air cleaner model 104 calculates a value that satisfies the relationship of equation (1) as the value of the throttle upstream pressure PAC based on the intake air temperature THA, the atmospheric pressure PA, and the throttle flow rate MT. "R" in equation (1) represents the gas constant of the intake air.

<About Throttle Model 105>
Next, the throttle model 105 will be described in detail. In the ECM 30, the throttle model 105 is implemented as a function that takes the intake air temperature THA, the throttle upstream pressure PAC, the throttle downstream pressure PM, and the throttle opening TA as inputs and outputs the throttle flow rate MT. The throttle model 105 calculates the throttle flow rate MT as a value that satisfies the relationship shown in equation (2). "μ" in equation (2) represents a flow coefficient. Furthermore, "RP" in equation (2) represents a throttle front/rear pressure ratio, which is the ratio of the throttle downstream pressure PM to the throttle upstream pressure PAC (=PM/PAC). Furthermore, "AT" in equation (2) represents the opening area of the throttle valve 17, and its value is calculated from the throttle opening TA.

The "Φ" in equation (2) is a value that satisfies the relationship shown in equation (3). In the following explanation, this value will be referred to as the Φ value. The "κ" in equation (3) represents the specific heat ratio of the intake air. The Φ value is uniquely determined by the pressure ratio RP before and after the throttle.

Figure 3 shows the relationship between the Φ value and the throttle front/rear pressure ratio RP. When the throttle front/rear pressure ratio RP is "1/(κ+1)" or less, the flow velocity of the intake air passing through the throttle valve 17 is equal to or greater than the sonic speed. In the following description, the region where the flow velocity of the intake air passing through the throttle valve 17 is equal to or greater than the sonic speed is referred to as the sonic speed region. The Φ value represents the rate of change of the throttle flow rate MT due to the throttle front/rear pressure ratio RP. When the throttle front/rear pressure ratio RP is "1", that is, when there is no pressure difference before and after the throttle valve 17, no intake air flows through the throttle valve 17. The Φ value at this time is "0". On the other hand, in the sonic speed region where the throttle front/rear pressure ratio RP is "1/(κ+1)" or less, the Φ value is a constant value. And, in the range where the throttle front/rear pressure ratio RP is "1/(κ+1)" or more and "1" or less, the Φ value increases as the throttle front/rear pressure ratio RP decreases.

The above formula (2) can be expressed as formula (4) using standard pressure PA0 and standard temperature TH0. "μs" in formula (4) represents the value of the flow coefficient μ when the throttle upstream pressure PAC is the standard pressure PA0 and the intake air temperature THA is the standard temperature TH0.

Here, the value of "B" that satisfies the relationship in equation (5) is defined as the B value. The B value is uniquely determined by the throttle opening TA. The value of "KTHA" that satisfies the relationship in equation (6) is defined as the temperature correction coefficient. Furthermore, the value of "KPAC" that satisfies the relationship in equation (7) is defined as the pressure correction coefficient. The throttle flow rate MT at this time can be expressed as the product of the B value, the temperature correction coefficient KTHA, the pressure correction coefficient KPAC, and the Φ value, as shown in equation (8). The throttle model 105 implemented in the ECM 30 is configured to calculate the throttle flow rate MT according to equation (8).

<Regarding the intake pipe model 106>
Next, the intake pipe model 106 will be described in detail. In the ECM 30, the intake pipe model 106 is implemented as a function that receives the throttle flow rate MT, the intake air temperature THA, and the in-cylinder intake air amount MC as inputs, and outputs the throttle downstream pressure PM and the throttle downstream temperature THM. The throttle downstream temperature THM represents the temperature of the intake air in the intake manifold 12A. The intake pipe model 106 calculates the throttle downstream pressure PM and the throttle downstream temperature THM based on the relational expressions (9) and (10). The relational expressions (9) and (10) are derived from the law of conservation of mass and the law of conservation of energy. "VM" in the expressions (9) and (10) represents the volume of the intake manifold 12A.

<Regarding the intake valve model 107>
Next, the intake valve model 107 will be described in detail. In the ECM 30, the intake valve model 107 is implemented as the following function. That is, it is a function that takes the throttle downstream pressure PM, the intake valve timing VTI, the intake air temperature THA, and the throttle downstream temperature THM as inputs, and the amount of intake air in the cylinder MC as output. The actual flow of intake air from the intake manifold 12A to the combustion chamber 11 occurs intermittently in response to the opening and closing of the intake valve 19. In the intake valve model 107, a flow rate that approximates this as a continuous uniform flow is obtained as the amount of intake air in the cylinder MC.

The curve L0 shown by the dashed line in FIG. 4 indicates the relationship between the throttle downstream pressure PM and the amount of intake air in the cylinder MC when the engine 10 is operated steadily with the engine speed NE and the operating amount of the variable valve mechanisms 20, 22 kept constant. In the intake valve model 107, the intake air amount MC in the cylinder is calculated by approximating this curve L0 using two straight lines L1 and L2 shown in FIG. 4. That is, in the intake valve model 107, the value of the intake air amount MC in the cylinder is calculated as a value that satisfies the relationship of equation (11). "GL", "GH", "PMC", and "MCC" in equation (11) are coefficients that are determined based on the engine speed NE and the intake valve timing VTI, respectively.

The calculated value of the in-cylinder intake air amount MC by the air cleaner model 104, throttle model 105, intake pipe model 106, and intake valve model 107 described above is set as the model value of the in-cylinder intake air amount MC. The model value may deviate from the actual in-cylinder intake air amount MC due to factors not taken into account in each of the above physical models. The engine control device of this embodiment corrects such deviations in the model values by the first shift correction 108 and the second shift correction 109. The first shift correction 108 is a correction to the calculated value of the throttle flow rate MT by the throttle model 105 in the throttle flow rate calculation process 101. The second shift correction 109 is a correction to the calculated value of the in-cylinder intake air amount MC by the intake valve model 107 in the in-cylinder intake air amount calculation process 103.

<Regarding First Shift Correction 108>
First, the first shift correction 108 will be described in detail. The intake air flows from the intake manifold 12A into the combustion chamber 11 intermittently in response to the opening and closing of the intake valve 19. As a result, intake air pulsation occurs in the intake passage 12 while the engine 10 is running. This intake air pulsation may cause intermittent backflow of intake air, where the intake air passes through the throttle valve 17 and flows upstream of the intake passage 12.

On the other hand, the throttle model 105 is configured on the assumption that intake air flows uniformly from upstream to downstream of the intake passage 12. Therefore, in a situation where intake air flows backward, the calculated value of the throttle flow rate MT by the throttle model 105 deviates from the actual value.

In FIG. 3, the relationship between the actual Φ value when backflow occurs and the throttle front/rear pressure ratio RP is shown by a broken line. When backflow occurs, the Φ value deviates by the amount shown by hatching in FIG. 3. Note that intake backflow is likely to occur when the intake flow rate is small, that is, when the throttle front/rear pressure ratio RP is close to "1". In the first shift correction 108, the deviation of the Φ value due to the occurrence of backflow is corrected. The range of the throttle front/rear pressure ratio RP in which backflow occurs and the deviation of the Φ value due to backflow vary depending on the opening and closing timing of the intake valve 19, the valve overlap amount of the intake valve 19 and the exhaust valve 21, and the amount of exhaust gas recirculated into the intake air. Therefore, the ECM 30 performs the first shift correction 108 to correct the Φ value based on the intake valve timing VTI, the exhaust valve timing VTE, and the EGR opening DEGR. In the first shift correction 108, the intake valve timing VTI and the exhaust valve timing VTE are used as state quantities indicating the operating amount of the variable valve mechanisms 20, 22 that determine the opening and closing timing of the intake valve 19 and the valve overlap amount of the intake valve 19 and the exhaust valve 21. In addition, the EGR opening DEGR is used as a state quantity indicating the amount of exhaust gas recirculated into the intake air.

Figure 5 shows a control block diagram of the throttle flow rate calculation process 101 to which the first shift correction 108 is applied. In the throttle flow rate calculation process 101, the ECM 30 calculates the throttle flow rate MT using the throttle model 105. That is, the ECM 30 calculates the B value from the throttle opening TA, the temperature correction coefficient KTHA from the intake air temperature THA, the pressure correction coefficient KPAC from the throttle upstream pressure PAC, and the Φ value from the throttle front-rear pressure ratio RP. The memory device 32 of the ECM 30 stores the B value for each value of the throttle opening TA, which has been previously obtained through experiments, etc., as a map 110. The memory device 32 also stores the Φ value for each value of the throttle front-rear pressure ratio RP, which has been previously obtained through experiments, etc., as a map 112. The ECM 30 calculates the B value using the map 110 and the Φ value using the map 112. In addition, the ECM 30 calculates the temperature correction coefficient KTHA according to the above-mentioned equation (6) and the pressure correction coefficient KPAC according to the above-mentioned equation (7). The throttle flow rate MT by the throttle model 105 is calculated as the product of the B value, the temperature correction coefficient KTHA, the pressure correction coefficient KPAC, and the Φ value calculated in this way.

Meanwhile, in the throttle flow calculation process 101, the ECM 30 corrects the Φ value using the first shift correction 108. During the first shift correction 108, the ECM 30 calculates three correction values SF11, SF12, and SF13.

The correction value SF11 is a correction value that corrects the change in the deviation amount of the Φ value due to a change in the intake valve timing VTI. The ECM 30 uses a map 113 stored in the storage device 32 to calculate the value of the correction value SF11 based on the intake valve timing VTI, the engine speed NE, and the throttle front-rear pressure ratio RP. The map 113 is created as follows. First, the deviation amount of the Φ value when the intake valve timing VTI is changed at each operating point of the engine 10 defined by the engine speed NE and the throttle front-rear pressure ratio RP is obtained by simulation or the like. Then, the deviation amount is stored as the correction value SF11 for each value of the engine speed NE, the throttle front-rear pressure ratio RP, and the intake valve timing VTI, and the map 113 is created.

The correction value SF12 is a correction value that corrects the change in the deviation amount of the Φ value due to a change in the exhaust valve timing VTE. The ECM 30 uses a map 114 stored in the storage device 32 to calculate the value of the correction value SF12 based on the exhaust valve timing VTE, the engine speed NE, and the throttle front-rear pressure ratio RP. The map 114 is created as follows. First, the deviation amount of the Φ value when the exhaust valve timing VTE is changed at each operating point of the engine 10 defined by the engine speed NE and the throttle front-rear pressure ratio RP is obtained by simulation or the like. Then, the deviation amount is stored as the correction value SF12 for each value of the engine speed NE, the throttle front-rear pressure ratio RP, and the exhaust valve timing VTE, and is created as the map 114.

The correction value SF13 is a correction value that corrects the change in the deviation amount of the Φ value due to the change in the EGR opening degree DEGR. The ECM 30 uses a map 115 stored in the storage device 32 to calculate the value of the correction value SF13 based on the EGR opening degree DEGR, the engine speed NE, and the throttle front-rear pressure ratio RP. The map 115 is created as follows. First, the deviation amount of the Φ value when the EGR opening degree DEGR is changed at each operating point of the engine 10 defined by the engine speed NE and the throttle front-rear pressure ratio RP is obtained by simulation or the like. Then, the deviation amount is stored as the correction value SF13 for each value of the engine speed NE, the throttle front-rear pressure ratio RP, and the EGR opening degree DEGR, and is created as the map 115.

Furthermore, in the first shift correction 108, the ECM 30 calculates the sum of the three correction values SF11, SF12, and SF13 as the value of the first shift correction value SF1. Next, the ECM 30 corrects the Φ value calculated using the map 112 in the throttle model 105 with the first shift correction value SF1. Then, the ECM 30 calculates the product of the B value, the temperature correction coefficient KTHA, the pressure correction coefficient KPAC, and the corrected Φ value as the value of the throttle flow rate MT.

<Regarding the Second Shift Correction 109>
Next, the second shift correction 109 will be described in detail. As shown in FIG. 4, the intake valve model 107 calculates the intake air amount MC in the cylinder by approximating the relationship between the throttle downstream pressure PM and the intake air amount MC in the cylinder by two straight lines L1 and L2. The calculated value of the intake air amount MC in the cylinder by the intake valve model 107 includes an approximation error. The magnitude of the approximation error varies depending on the opening and closing timing of the intake valve 19, the valve overlap amount of the intake valve 19 and the exhaust valve 21, and the EGR amount. In addition, the back pressure increase of the engine 10 due to clogging of the filter device 23 also affects the approximation error. The ECM 30 obtains the differential pressure increase rate RPF as a state quantity indicating the degree of clogging of the filter device 23 from the detection result of the filter differential pressure ΔP by the differential pressure sensor 36. The differential pressure increase rate RPF is the ratio of the current filter differential pressure ΔP to the filter differential pressure ΔP in a state without clogging. Then, the ECM 30 performs second shift correction 109 by correcting the calculated value of the in-cylinder intake air amount MC of the intake valve model 107 based on the intake valve timing VTI, the exhaust valve timing VTE, the EGR opening DEGR, and the differential pressure rise rate RPF. In this second shift correction 109, the intake valve timing VTI and the exhaust valve timing VTE are also used as operating amounts of the variable valve mechanisms 20, 22. The EGR opening DEGR is also used as a state amount indicating the amount of exhaust gas recirculated into the intake air. Furthermore, in the second shift correction 109, the differential pressure rise rate RPF is used as a state amount indicating the degree of clogging of the filter device 23.

Figure 6 shows a control block diagram of the in-cylinder intake air amount calculation process 103 to which the second shift correction 109 is applied. During the in-cylinder intake air amount calculation process 103, the ECM 30 uses a map 120 previously stored in the storage device 32 to calculate the values of the coefficients PMC, MCC, GL, and GH based on the engine speed NE and the intake valve timing VTI. Then, in process 121, the ECM 30 calculates the value of the in-cylinder intake air amount MC in the intake valve model 107 based on the results of these calculations as a value that satisfies the relationship of the above-mentioned equation (11).

Meanwhile, the ECM 30 corrects the in-cylinder intake air amount MC by the second shift correction 109. During the second shift correction 109, the ECM 30 calculates four correction values SF21, SF22, SF23, and SF24.

The correction value SF21 is a correction value that corrects the change in the approximation error of the intake air amount MC in the cylinder due to the change in the intake valve timing VTI. The ECM 30 uses a map 122 stored in the storage device 32 to calculate the value of the correction value SF21 based on the intake valve timing VTI, the engine speed NE, and the throttle downstream pressure PM. The map 122 is created as follows. First, by simulation or the like, the approximate error amount of the calculated value of the intake air amount MC in the cylinder by the intake valve model 107 when the intake valve timing VTI is changed at each operating point of the engine 10 defined by the engine speed NE and the throttle downstream pressure PM is obtained. Then, the approximate error amount is stored as the correction value SF21 for each value of the engine speed NE, the throttle downstream pressure PM, and the intake valve timing VTI, and the map 122 is created.

The correction value SF22 is a correction value that corrects the change in the approximate error amount of the intake air amount MC in the cylinder due to the change in the exhaust valve timing VTE. The ECM 30 uses a map 123 stored in the storage device 32 to calculate the value of the correction value SF22 based on the exhaust valve timing VTE, the engine speed NE, and the throttle downstream pressure PM. The map 122 is created as follows. First, by a simulation or the like, the approximate error amount of the calculated value of the intake air amount MC in the cylinder by the intake valve model 107 when the exhaust valve timing VTE is changed at each operating point of the engine 10 defined by the engine speed NE and the throttle downstream pressure PM is obtained. Then, the approximate error amount is stored as the correction value SF22 for each value of the engine speed NE, the throttle downstream pressure PM, and the exhaust valve timing VTE, and the map 122 is created.

The correction value SF23 is a correction value that corrects the change in the approximate error amount of the intake air amount MC in the cylinder due to the change in the EGR opening DEGR. The ECM 30 uses a map 124 stored in the storage device 32 to calculate the value of the correction value SF23 based on the EGR opening DEGR, the engine speed NE, and the throttle downstream pressure PM. The map 124 is created as follows. First, the approximate error amount of the intake air amount MC in the cylinder when the EGR opening DEGR is changed at each operating point of the engine 10 defined by the engine speed NE and the throttle downstream pressure PM is obtained by simulation or the like. Then, the approximate error amount is stored as the correction value SF23 for each value of the engine speed NE, the throttle downstream pressure PM, and the EGR opening DEGR, and the map 124 is created.

The correction value SF24 is a correction value that corrects the change in the approximate error amount of the intake air amount MC in the cylinder due to the change in the differential pressure rise rate RPF. The ECM 30 uses a map 125 stored in the memory device 32 to calculate the value of the correction value SF24 based on the differential pressure rise rate RPF, the engine speed NE, and the throttle downstream pressure PM. The map 125 is created as follows. First, the approximate error amount of the intake air amount MC in the cylinder when the differential pressure rise rate RPF is changed at each operating point of the engine 10 defined by the engine speed NE and the throttle downstream pressure PM is obtained by simulation or the like. Then, the approximate error amount is stored as the correction value SF24 for each value of the engine speed NE, the throttle downstream pressure PM, and the differential pressure rise rate RPF, and the map 125 is created.

Furthermore, in the second shift correction 109, the ECM 30 calculates the sum of the above four correction values SF21, SF22, SF23, and SF24 as the value of the second shift correction value SF2. Then, the ECM 30 calculates the value of the in-cylinder intake air amount MC calculated by the intake valve model 107, corrected by the second shift correction value SF2, as the final calculated value of the in-cylinder intake air amount MC in the in-cylinder intake air amount calculation process 103.

<Functions and Effects of First Embodiment>
The ECM 30 in the engine control device of this embodiment calculates the in-cylinder intake air amount MC using each of the physical models, namely, the air cleaner model 104, the throttle model 105, the intake pipe model 106, and the intake valve model 107. The physical models used to calculate the in-cylinder intake air amount MC need to be simplified models due to limitations in the processing capacity of the ECM 30 and the time required to complete the calculation. Therefore, the behavior of the intake air in the physical models may deviate from the actual behavior, which may cause an error in the calculation result of the in-cylinder intake air amount MC.

On the other hand, if the error of the physical model for each operating state of the engine 10 is known in advance, an adaptation map can be created to correct the error. However, creating such an adaptation map requires measuring the in-cylinder intake air amount MC of the engine 10 at a huge number of operating points, and the amount of work required for the measurement is also enormous. On the other hand, it is possible to create a simulation model that accurately reproduces the intake behavior of the engine 10 unless implementation in an engine control device is assumed. However, since numerous factors affect the intake behavior of the entire intake system of the engine 10, and the mechanisms of these effects are complex, creating such a simulation model is difficult. In comparison, it is easy to create a simulation model limited to the intake behavior at the throttle valve 17 or the intake valve 19.

In the engine control device of this embodiment, the error of the physical model is separated into an error of the throttle model 105 and an error of the intake valve model 107. Then, the error of the throttle model 105 is corrected by the first shift correction 108, and the error of the intake valve model 107 is corrected by the second shift correction 109, respectively. In the first shift correction 108, the first shift correction value SF1, which is a correction value that corrects the error of the throttle model 105, is calculated using maps 113 to 115. The data required for creating these maps 113 to 115 can be collected using a simulation model limited to the behavior of the intake at the throttle valve 17. On the other hand, in the second shift correction 109, the second shift correction value SF2, which is a correction value that corrects the error of the intake valve model 107, is calculated using maps 122 to 125. The data required for creating these maps 122 to 125 can be collected using a simulation model limited to the behavior of the intake at the intake valve 19. Therefore, the engine control device of this embodiment has the effect of reducing the amount of work required for adaptation to correct errors in the physical model.

When the engine 10 is installed in multiple vehicle models, the operating range of the engine 10 may vary depending on the vehicle model. It is difficult to actually measure the errors of the throttle model 105 and the intake valve model 107 in operating conditions outside the operating range. Therefore, when checking the errors of the throttle model 105 and the intake valve model 107 by actual measurement, it may be necessary to actually measure the errors for each vehicle model in which the engine 10 is installed. In contrast, a simulation may be able to reproduce operating conditions that are difficult to achieve in an actual machine. Therefore, if it becomes possible to check the errors of the throttle model 105 and the intake valve model 107 by simulation, it will be easy to deploy the same model of engine 10 in multiple vehicle models.

According to the engine control device of the present embodiment described above, the following effects can be achieved.
(1) In this embodiment, the error of the calculated value of the in-cylinder intake air amount MC using the physical model is corrected by the following two corrections. One is a first shift correction 108 that corrects the calculated value of the throttle flow rate MT by the throttle model 105. The other is a second shift correction 109 that corrects the calculated value of the in-cylinder intake air amount MC by the intake valve model 107. By correcting the error of the physical model by these two corrections, it becomes possible to calculate the in-cylinder intake air amount MC with high accuracy. In addition, when the error of the physical model is corrected by the two corrections of the first shift correction 108 and the second shift correction 109, the man-hours required to create the adaptation map required for the correction are reduced. Therefore, the engine control device of this embodiment has the effect of easily improving the accuracy of the calculation of the in-cylinder intake air amount MC.

(2) Since the errors in the throttle model 105 and the intake valve model 107 can be measured by simulation, the same model of engine 10 can be easily applied to a variety of vehicle models.
(3) When the opening and closing timing of the intake valve 19 or the valve overlap amount of the intake valve 19 and the exhaust valve 21 changes, the occurrence state of intake pulsation in the intake passage 12 changes. Therefore, the error of the throttle model 105 changes depending on the operation amount of the variable valve mechanisms 20, 22. In this embodiment, the first shift correction 108 is performed using the intake valve timing VTI and the exhaust valve timing VTE, which indicate the operation amount of the variable valve mechanisms 20, 22. Therefore, by using the intake valve timing VTI and the exhaust valve timing VTE, the error of the throttle model 105 due to the backflow of intake air can be accurately corrected.

(4) When the opening and closing timing of the intake valve 19 or the valve overlap amount of the intake valve 19 and the exhaust valve 21 changes, the action of the inertia effect and the scavenging effect on the intake filling rate of the combustion chamber 11 changes. Therefore, the error of the intake valve model 107 also changes depending on the operation amount of the variable valve mechanisms 20, 22. In this embodiment, the second shift correction 109 is performed using the intake valve timing VTI and the exhaust valve timing VTE, which indicate the operation amount of the variable valve mechanisms 20, 22. Therefore, by using the intake valve timing VTI and the exhaust valve timing VTE, the error of the intake valve model 107 due to the change in the intake filling efficiency caused by the operation of the variable valve mechanisms 20, 22 can be accurately corrected.

(5) When the amount of exhaust gas recirculated changes, the mass of gas present in the intake passage 12 changes, and the occurrence of intake pulsation changes. Therefore, the error of the throttle model 105 also changes depending on the amount of exhaust gas recirculated. In this embodiment, the first shift correction 108 is performed using the EGR opening DEGR, which is a state quantity that indicates the amount of exhaust gas recirculated into the intake air. Therefore, by using the EGR opening DEGR, the error of the throttle model 105 due to the backflow of intake air can be accurately corrected.

(6) The exhaust gas recirculated during intake flows into the combustion chamber 11 together with the intake air. Therefore, even if the flow rate of gas flowing into the combustion chamber 11 is the same, if the amount of exhaust gas recirculation increases, the actual amount of intake air flowing into the combustion chamber 11 decreases. Therefore, the error of the intake valve model 107 also changes depending on the amount of exhaust gas recirculated. In this embodiment, the second shift correction 109 is performed using the EGR opening DEGR, which is a state quantity that indicates the amount of exhaust gas recirculated into the intake air. Therefore, the error of the intake valve model 107 due to exhaust gas recirculation can be accurately corrected.

(7) When the filter device 23 becomes clogged and the back pressure of the engine 10 increases, it becomes difficult for intake air to enter the combustion chamber 11. Therefore, the error of the intake valve model 107 also changes depending on the degree of clogging of the filter device 23. In this embodiment, the second shift correction 109 is performed using the differential pressure rise rate RPF, which is a state quantity that indicates the degree of clogging of the filter device 23. Therefore, the error of the intake valve model 107 caused by the increase in back pressure due to clogging of the filter device 23 can be accurately corrected.

Second Embodiment
Next, a second embodiment of the engine control device will be described in detail with reference to Fig. 7. In this embodiment, the same components as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. The difference between this embodiment and the first embodiment is in the method of correcting the error of the intake valve model 107 by the second shift correction 109.

In the engine control device of this embodiment, the ECM 30 calculates the second shift correction value SF2 during the second shift correction 109 as a value that satisfies the relationship of equation (12). In equation (12), "PM0", "AL", "AH", "BL", "BH", and "C" are coefficients calculated based on the engine speed NE, the intake valve timing VTI, the exhaust valve timing VTE, the EGR opening DEGR, and the differential pressure rise rate RPF, respectively.

Figure 7 shows the relationship between the second shift correction value SF2 and the throttle downstream pressure PM when the coefficients PM0, AL, AH, BL, BH, and C are fixed. In this case, the second shift correction value SF2 is represented by two curves L3 and L4 with "PM0" as the boundary for the throttle downstream pressure PM. The two curves L3 and L4 are curves represented as quadratic functions of the throttle downstream pressure PM.

As described above, in the intake valve model 107, the relationship between the throttle downstream pressure PM and the in-cylinder intake air amount MC is approximated by two straight lines L1 and L2 (see FIG. 4). When the relationship between the in-cylinder intake air amount MC and the throttle downstream pressure PM is approximated by a quadratic function, the error of the intake valve model 107 can be expressed by two quadratic functions. Therefore, the correction method of this embodiment can correct the error of the intake valve model 107 in the same way as in the first embodiment.

The above embodiment can be modified as follows: The present embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.
In the above embodiment, the error of the throttle model 105 is corrected by the first shift correction value 108 by correcting the Φ value by the first shift correction value SF1. The error of the throttle model 105 may be corrected by the first shift correction value 108 in a different manner, such as by correcting the calculated value of the throttle flow rate MT of the throttle model 105 by the first shift correction value SF1.

- In the above embodiment, the first shift correction value SF1 is calculated based on five state quantities, namely, the engine speed NE, the throttle front/rear pressure ratio RP, the intake valve timing VTI, the exhaust valve timing VTE, and the EGR opening DEGR. One or more of the above five state quantities may be omitted from the state quantities used in the calculation of the first shift correction value SF1. Also, a state quantity other than the above five state quantities may be added to the state quantities used in the calculation of the first shift correction value SF1. In short, among the state quantities indicating the operating state of the engine 10, a state quantity that has a large effect on the error of the throttle model 105 may be selected and used in the calculation of the first shift correction value SF1.

- In the above embodiment, the second shift correction value SF2 is calculated based on six state quantities, namely, the engine speed NE, the throttle front/rear pressure ratio RP, the intake valve timing VTI, the exhaust valve timing VTE, the EGR opening DEGR, and the differential pressure rise rate RPF. One or more of the six state quantities may be omitted from the state quantities used to calculate the second shift correction value SF2. Also, a state quantity other than the six state quantities may be added to the state quantities used to calculate the second shift correction value SF2. In short, among the state quantities indicating the operating state of the engine 10, a state quantity that has a large effect on the error of the intake valve model 107 may be selected and used to calculate the second shift correction value SF2.

- In the above embodiment, variable valve mechanisms 20, 22 are used to vary the opening and closing timing of the intake valve 19 and exhaust valve 21, but a mechanism that varies valve characteristics other than the opening and closing timing, such as the valve lift amount, may also be used. Even in this case, the accuracy of calculating the in-cylinder intake air amount MC can be improved by performing the first shift correction 108 and the second shift correction 109 using a state quantity that indicates the operating amount of the variable valve mechanism.

In the above embodiment, the first shift correction 108 and the second shift correction 109 are performed using the EGR opening DEGR. Instead of the EGR opening DEGR, another state quantity indicating the amount of exhaust gas recirculated, such as a measured value or an estimated value of the recirculation amount, may be used.

- In the above embodiment, the second shift correction 109 was performed using the differential pressure rise rate RPF. Instead of the differential pressure rise rate RPF, another state quantity indicating the degree of clogging of the filter device 23, for example, an estimated value of the amount of particulate matter accumulated in the filter device 23, may be used.

The contents of the air cleaner model 104, the throttle model 105, the intake pipe model 106, and the intake valve model 107 may be changed as appropriate.
In cases where the influence of the intake pressure loss in the air cleaner 16 on the in-cylinder intake air amount MC is small, the air cleaner model 104 may not be included in the physical model used to calculate the in-cylinder intake air amount MC.

- In the case of an engine equipped with a turbocharger, it is advisable to use the pressure of the intake air after turbocharging as the throttle upstream pressure PAC used to calculate the throttle flow rate MT in the throttle model 105. In addition, in this case, it is advisable to use the temperature of the intake air after turbocharging in the throttle model 105 instead of the intake air temperature THA.

REFERENCE SIGNS LIST 10 engine 11 combustion chamber 12 intake passage 12A intake manifold 13 exhaust passage 14 injector 15 ignition device 16 air cleaner 17 throttle valve 18 throttle motor 19 intake valve 20, 22 variable valve mechanism 21 exhaust valve 23 filter device 24 EGR passage 25 EGR cooler 26 EGR valve 30 ECM (engine control module)
31: Processing device 32: Storage device 33: Intake pressure sensor 34: Intake temperature sensor 35: Throttle opening sensor 36: Differential pressure sensor 37: Crankshaft 38: Crank angle sensor 39: Accelerator pedal 40: Accelerator pedal sensor 100: Throttle upstream pressure calculation process 101: Throttle flow rate calculation process 102: Throttle downstream pressure calculation process 103: In-cylinder intake amount calculation process 104: Air cleaner model 105: Throttle model 106: Intake pipe model 107: Intake valve model 108: First shift correction 109: Second shift correction

Claims (5)

When the amount of intake air flowing into the combustion chamber from the intake passage of the engine is defined as the in-cylinder intake air amount, the opening of a throttle valve installed in the intake passage is defined as the throttle opening, the pressure of the intake air before passing through the throttle valve is defined as the throttle upstream pressure, the pressure of the intake air after passing through the throttle valve is defined as the throttle downstream pressure, and the flow rate of the intake air passing through the throttle valve is defined as the throttle flow rate,
a throttle flow rate calculation process that calculates the throttle flow rate based on the throttle opening, the throttle upstream pressure, and the throttle downstream pressure by using a throttle model that is a physical model regarding the behavior of the intake air passing through the throttle valve;
a throttle downstream pressure calculation process that calculates the throttle downstream pressure based on the throttle flow rate and the in-cylinder intake air amount by using an intake pipe model that is a physical model regarding the behavior of the intake air flowing in a portion of the intake passage downstream of the throttle valve;
an intake air amount calculation process for calculating the intake air amount in the cylinder based on the throttle downstream pressure by using an intake valve model which is a physical model of the behavior of the intake air flowing from the intake passage into the combustion chamber;
a first shift correction for correcting a calculated value of the throttle flow rate by the throttle model based on a state quantity indicating an operating state of the engine;
a second shift correction for correcting a calculated value of the in-cylinder intake air amount by the intake valve model based on a state quantity indicating an operating state of the engine;
Do the following:
the engine is equipped with a variable valve mechanism that varies a valve characteristic of an engine valve, and the state quantity used to correct the calculated value of the throttle flow rate in the first shift correction includes an operating quantity of the variable valve mechanism . When the amount of intake air flowing into the combustion chamber from the intake passage of the engine is defined as the in-cylinder intake air amount, the opening of a throttle valve installed in the intake passage is defined as the throttle opening, the pressure of the intake air before passing through the throttle valve is defined as the throttle upstream pressure, the pressure of the intake air after passing through the throttle valve is defined as the throttle downstream pressure, and the flow rate of the intake air passing through the throttle valve is defined as the throttle flow rate,
a throttle flow rate calculation process that calculates the throttle flow rate based on the throttle opening, the throttle upstream pressure, and the throttle downstream pressure by using a throttle model that is a physical model regarding the behavior of the intake air passing through the throttle valve;
a throttle downstream pressure calculation process that calculates the throttle downstream pressure based on the throttle flow rate and the in-cylinder intake air amount by using an intake pipe model that is a physical model regarding the behavior of the intake air flowing in a portion of the intake passage downstream of the throttle valve;
an intake air amount calculation process for calculating the intake air amount in the cylinder based on the throttle downstream pressure by using an intake valve model which is a physical model of the behavior of the intake air flowing from the intake passage into the combustion chamber;
a first shift correction for correcting a calculated value of the throttle flow rate by the throttle model based on a state quantity indicating an operating state of the engine;
a second shift correction for correcting a calculated value of the in-cylinder intake air amount by the intake valve model based on a state quantity indicating an operating state of the engine;
Do the following:
The engine is equipped with a variable valve mechanism that varies the valve characteristics of an engine valve, and the state quantity used to correct the calculated value of the in-cylinder intake air amount in the second shift correction includes an operating quantity of the variable valve mechanism . When the amount of intake air flowing into the combustion chamber from the intake passage of the engine is defined as the in-cylinder intake air amount, the opening of a throttle valve installed in the intake passage is defined as the throttle opening, the pressure of the intake air before passing through the throttle valve is defined as the throttle upstream pressure, the pressure of the intake air after passing through the throttle valve is defined as the throttle downstream pressure, and the flow rate of the intake air passing through the throttle valve is defined as the throttle flow rate,
a throttle flow rate calculation process that calculates the throttle flow rate based on the throttle opening, the throttle upstream pressure, and the throttle downstream pressure by using a throttle model that is a physical model regarding the behavior of the intake air passing through the throttle valve;
a throttle downstream pressure calculation process that calculates the throttle downstream pressure based on the throttle flow rate and the in-cylinder intake air amount by using an intake pipe model that is a physical model regarding the behavior of the intake air flowing in a portion of the intake passage downstream of the throttle valve;
an intake air amount calculation process for calculating the intake air amount in the cylinder based on the throttle downstream pressure by using an intake valve model which is a physical model of the behavior of the intake air flowing from the intake passage into the combustion chamber;
a first shift correction for correcting a calculated value of the throttle flow rate by the throttle model based on a state quantity indicating an operating state of the engine;
a second shift correction for correcting a calculated value of the in-cylinder intake air amount by the intake valve model based on a state quantity indicating an operating state of the engine;
Do the following:
The engine control device is one in which exhaust gas is recirculated into an intake air, and the state quantity used to correct the calculated value of the throttle flow rate in the first shift correction includes a state quantity indicating an amount of exhaust gas recirculated . When the amount of intake air flowing into the combustion chamber from the intake passage of the engine is defined as the in-cylinder intake air amount, the opening of a throttle valve installed in the intake passage is defined as the throttle opening, the pressure of the intake air before passing through the throttle valve is defined as the throttle upstream pressure, the pressure of the intake air after passing through the throttle valve is defined as the throttle downstream pressure, and the flow rate of the intake air passing through the throttle valve is defined as the throttle flow rate,
a throttle flow rate calculation process that calculates the throttle flow rate based on the throttle opening, the throttle upstream pressure, and the throttle downstream pressure by using a throttle model that is a physical model of the behavior of the intake air passing through the throttle valve;
a throttle downstream pressure calculation process that calculates the throttle downstream pressure based on the throttle flow rate and the in-cylinder intake air amount by using an intake pipe model that is a physical model regarding the behavior of the intake air flowing in a portion of the intake passage downstream of the throttle valve;
an intake air amount calculation process for calculating the intake air amount in the cylinder based on the throttle downstream pressure by using an intake valve model which is a physical model of the behavior of the intake air flowing from the intake passage into the combustion chamber;
a first shift correction for correcting a calculated value of the throttle flow rate by the throttle model based on a state quantity indicating an operating state of the engine;
a second shift correction for correcting a calculated value of the in-cylinder intake air amount by the intake valve model based on a state quantity indicating an operating state of the engine;
Do the following:
The engine recirculates exhaust gas into the intake air, and the state quantity used to correct the calculated value of the in-cylinder intake air amount in the second shift correction includes a state quantity indicating the amount of exhaust gas recirculated . When the amount of intake air flowing into the combustion chamber from the intake passage of the engine is defined as the in-cylinder intake air amount, the opening of a throttle valve installed in the intake passage is defined as the throttle opening, the pressure of the intake air before passing through the throttle valve is defined as the throttle upstream pressure, the pressure of the intake air after passing through the throttle valve is defined as the throttle downstream pressure, and the flow rate of the intake air passing through the throttle valve is defined as the throttle flow rate,
a throttle flow rate calculation process that calculates the throttle flow rate based on the throttle opening, the throttle upstream pressure, and the throttle downstream pressure by using a throttle model that is a physical model of the behavior of the intake air passing through the throttle valve;
a throttle downstream pressure calculation process that calculates the throttle downstream pressure based on the throttle flow rate and the in-cylinder intake air amount by using an intake pipe model that is a physical model regarding the behavior of the intake air flowing in a portion of the intake passage downstream of the throttle valve;
an intake air amount calculation process for calculating the intake air amount in the cylinder based on the throttle downstream pressure by using an intake valve model which is a physical model of the behavior of the intake air flowing from the intake passage into the combustion chamber;
a first shift correction for correcting a calculated value of the throttle flow rate by the throttle model based on a state quantity indicating an operating state of the engine;
a second shift correction for correcting a calculated value of the in-cylinder intake air amount by the intake valve model based on a state quantity indicating an operating state of the engine;
Do the following:
The engine control device is equipped with a filter device that collects particulate matter in the exhaust gas, and the state quantity used to correct the calculated value of the in-cylinder intake air amount in the second shift correction includes a state quantity that indicates the degree of clogging of the filter device .

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