Control device for internal combustion engine and control method for internal combustion engine

Abstract

A control device for an internal combustion engine is provided with an in-cylinder air amount calculation unit for calculating the amount of air entering an internal combustion engine cylinder on the basis of an air flow sensor. Here, a control device for an internal combustion engine is provided with a calculation unit that calculates, on the basis of intake pipe pressure, an intermediate parameter indicating intake efficiency for calculating the amount of inflow air in a cylinder. The intermediate parameter is corrected on the basis of one or both of an estimated value and a measured value of a physical quantity that changes in accordance with a change in the combustion chamber wall surface temperature in the internal combustion engine cylinder.

Description

Technical Field

[0001] This invention relates to a control device and a control method for an internal combustion engine. Background Technology

[0002] It is essential to reduce the harmful components emitted from automobiles. Typically, to achieve this, a three-way catalytic converter is installed in the exhaust pipe of the car engine to purify these harmful components. For the three-way catalytic converter to effectively purify harmful components, the air-fuel ratio (air-fuel ratio) during combustion in the engine cylinders must be controlled within a specified range.

[0003] In the control used to maintain the air-fuel ratio within a specified range, an air flow sensor located in the engine's intake manifold and an intake manifold pressure sensor located in the intake manifold are used. The control then proceeds as follows: using these sensors, the air flow rate drawn into the engine cylinders is estimated, and the fuel injection quantity is determined based on the estimated value.

[0004] For example, in a system using an air flow sensor, the air flow rate measured by the sensor and the air flow rate drawn into the engine cylinders will differ under transient changes in engine operating conditions. Therefore, if the fuel injection quantity is determined based on the air flow rate measured by the air flow sensor, the air-fuel ratio may sometimes deviate from the specified range depending on the conditions.

[0005] Therefore, under conditions of transient changes in engine operating conditions, the estimated airflow into the engine cylinders is controlled. In the following description, this control will be referred to as intake air metering control.

[0006] Intake metering control of an engine equipped with an air flow sensor estimates the air flow rate drawn into the engine cylinder, for example, through the following process: The intake metering control estimates the intake manifold pressure (intake pipe pressure) based on the air flow rate measured by the air flow sensor, and estimates the air flow rate drawn into the engine cylinder based on the estimated intake pipe pressure and intermediate parameters calibrated in advance through experiments. This process of estimating the air flow rate drawn into the engine cylinder is repeated.

[0007] In conditions related to the performance of an internal combustion engine, such as the temperature of the combustion chamber walls (hereinafter referred to as wall temperature), suppose the engine's operating state switches from a low-output state to a high-output state, and then operates in a way that maintains a certain output. At this time, the temperature of the walls constituting the combustion chamber of the internal combustion engine, specifically the piston crown surface, cylinder liner wall surface, and cylinder head wall surface (combustion chamber wall temperature), will gradually increase until it reaches a certain temperature (stabilization temperature).

[0008] Conversely, if the engine's operating state switches from a high-output state to a low-output state, and then operates in a manner that maintains a certain output, the combustion chamber wall temperature will gradually decrease until it reaches a stable temperature. Under such conditions, the estimated intake manifold pressure value derived from intake metering control is prone to error. This is because the relationship between airflow determined by combustion chamber wall temperature and intake manifold pressure changes, and this change cannot be reproduced using conventional intake metering control.

[0009] As a prior art concerning the control of such internal combustion engines, a control device described in Patent Document 1 is known, for example. That is, Patent Document 1 discloses a control device for an internal combustion engine that has a mechanism for correcting the airflow drawn into the engine based on an estimated value of the combustion chamber wall temperature of the internal combustion engine.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent No. 7269104 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] However, in the prior art described in Patent Document 1, when correcting the airflow into the engine based on the estimated value of the combustion chamber wall temperature, it is necessary to know in advance the relationship between the combustion chamber wall temperature and intermediate parameters (intake efficiency), and investigating this relationship requires a large number of experiments. Furthermore, the calibration itself is required when estimating the combustion chamber wall temperature. Moreover, even if the combustion chamber wall temperature is estimated in the prior art, the accuracy of its correction needs to be confirmed.

[0015] The present invention was made in view of the above-mentioned problems, and its object is to provide a control device and a control method for an internal combustion engine, which can improve the reliability and accuracy of the estimation result when estimating the combustion chamber wall temperature by means of the change in combustion chamber wall temperature.

[0016] Methods for solving problems

[0017] To solve the above problems, for example, the configuration described in the technical solution may be adopted.

[0018] This application includes several mechanisms for solving the above-mentioned problems, but if we were to cite one example, it would be an in-cylinder air volume calculation unit that calculates the amount of air entering the cylinder of the internal combustion engine based on an air flow sensor.

[0019] Furthermore, the control unit of the internal combustion engine includes a calculation unit that calculates intermediate parameters representing intake efficiency based on the intake manifold pressure, used to calculate the amount of air flowing into the cylinder. These intermediate parameters are corrected based on one or both of the estimated or measured values ​​of a physical quantity that changes with the temperature of the combustion chamber wall inside the internal combustion engine cylinder.

[0020] The effects of the invention

[0021] According to the present invention, under conditions of transient changes in combustion chamber wall temperature, intermediate parameters used in intake air metering control for calculating the airflow into the engine based on measurements from an airflow sensor can be easily and appropriately corrected. Therefore, according to the present invention, the estimation error of the intake manifold pressure estimate can be reduced.

[0022] Other issues, structures, and effects not mentioned above will be clarified through the following description of the implementation methods. Attached Figure Description

[0023] Figure 1 This is a configuration diagram illustrating an example of the system configuration of an internal combustion engine according to the first embodiment of the present invention.

[0024] Figure 2 This is a block diagram illustrating an example of the hardware configuration of the ECU according to the first embodiment of the present invention.

[0025] Figure 3 This is a functional block diagram illustrating an intake metering control processing example of the first embodiment of the present invention.

[0026] Figure 4 This is a functional block diagram illustrating a processing example of the intake efficiency calculation unit in the first embodiment of the present invention.

[0027] Figure 5 This is a flowchart illustrating a processing example of the wall temperature correction unit of the intake efficiency calculation unit in the first embodiment of the present invention.

[0028] Figure 6 is a schematic diagram of the mapping for calculating the stable value of the intake manifold pressure according to the first embodiment of the present invention.

[0029] Figure 7 This is a characteristic graph showing the time variation of the estimated intake manifold pressure value when correcting the intermediate parameter (intake efficiency) based on the intake manifold pressure measurement value according to the first embodiment of the present invention.

[0030] Figure 8 is a schematic diagram illustrating an example of a mapping for calculating a stable value of airflow according to a first embodiment of the present invention.

[0031] Figure 9This is a characteristic diagram illustrating the time variation of the estimated intake manifold pressure value when correcting intermediate parameters (intake efficiency) based on the measured airflow value according to the first embodiment of the present invention.

[0032] Figure 10 is a schematic diagram illustrating an example of a mapping for calculating a stable value of gas flow rate according to a first embodiment of the present invention.

[0033] Figure 11 This is a characteristic graph showing the time variation of the estimated intake manifold pressure when correcting intermediate parameters (intake efficiency) based on the estimated gas flow rate in the first embodiment of the present invention.

[0034] Figure 12 This is a functional block diagram illustrating a processing example of the intake efficiency calculation unit in the second embodiment of the present invention.

[0035] Figure 13 This is a flowchart illustrating a processing example of the wall temperature correction unit of the intake efficiency calculation unit in the second embodiment of the present invention.

[0036] Figure 14 This is a schematic diagram illustrating an example of a mapping for calculating a stable wall temperature value according to a second embodiment of the present invention.

[0037] Figure 15 This is a characteristic diagram showing the time variation of the estimated intake manifold pressure when correcting the intermediate parameter (intake efficiency) based on the difference between the estimated wall temperature and the stable wall temperature (difference with the stable temperature) according to the second embodiment of the present invention.

[0038] Figure 16 This is a flowchart illustrating a processing example of the wall temperature correction unit of the intake efficiency calculation unit in the third embodiment of the present invention.

[0039] Figure 17 This is a characteristic graph showing the time variation of the estimated intake manifold pressure value when correcting the intermediate parameter (intake efficiency) based on the measured intake manifold pressure value and the estimated intake manifold pressure value according to the third embodiment of the present invention. Detailed Implementation

[0040] Hereinafter, control devices and control methods for internal combustion engines according to various embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, in the following embodiments, an internal combustion engine that uses gasoline as fuel and is installed in an automobile or the like will be used as an example for description; however, the present invention can also be applied to other internal combustion engines with different types, specifications, and uses of fuel.

[0041] <First Implementation Method>

[0042] Reference Figures 1-11 The first embodiment of the present invention will be described.

[0043] Figure 1 This is a diagram that roughly illustrates an example of the system configuration of an internal combustion engine mounted on a car, along with related components.

[0044] Figure 1 The internal combustion engine (ENG) illustrated is a spark-ignition, in-cylinder injection type internal combustion engine used in automobiles. That is, Figure 1 The internal combustion engine shown includes an in-cylinder fuel injection system that directly injects gasoline fuel into multiple cylinders, and an intake system that supplies air to the cylinders. Furthermore, Figure 1 The internal combustion engine shown includes an ignition mechanism for igniting the mixture of gasoline fuel and air injected into the cylinder, and an exhaust mechanism for expelling the combusted air from the cylinder. Additionally, in Figure 1 In this context, only one of the multiple cylinders is represented together with its associated components.

[0045] An internal combustion engine (ENG) includes an air flow sensor 1 that measures the amount of air intake (air flow rate) and intake air temperature, an intake pressure sensor 3 that measures intake manifold pressure (intake pressure), an electronically controlled throttle valve 2 that adjusts the intake manifold pressure, and an ECU 100 that controls the overall operation of the ENG. The intake manifold pressure regulated by the electronically controlled throttle valve 2 can be referred to as air flow rate. The air flow sensor 1 is called an AFS (Air Flow Sensor). The intake pressure sensor 3 is called a MAP (Manifold Absolute Pressure Sensor). ECU is an abbreviation for Electronic Control Unit.

[0046] The detection results (output information) of various sensors such as air flow sensor 1 and intake pressure sensor 3 are sent to ECU100.

[0047] Furthermore, the internal combustion engine ENG consists of a fuel injection device 13 (hereinafter also referred to as injector 13) that injects fuel into the cylinder block 14 of each cylinder, an ignition coil 16, and a spark plug 17. In addition, in the internal combustion engine ENG, each cylinder is equipped with an ignition device that supplies ignition energy to the fuel injected into the cylinder block 14.

[0048] The cylinder head is equipped with a variable valve 5 corresponding to each cylinder, which adjusts the air-fuel mixture flowing into the cylinder or the exhaust gas exiting the cylinder. Furthermore, by adjusting the variable valve 5, the intake volume and internal EGR of all cylinders in the cylinder head are adjusted.

[0049] Each cylinder has a fuel injection system 20 on the back of the piston to reduce piston temperature. The fuel injection system 20 is connected to a variable capacity (variable oil pressure) oil pump 20a, and the amount of oil injected from the fuel injection system 20 to the piston is adjusted by adjusting the output (flow rate, oil pressure) of the oil pump.

[0050] A high-pressure fuel pump (not shown) for supplying high-pressure fuel to the fuel injection device 13 is connected to the fuel injection device 13 via a fuel line. Additionally, the fuel injection device 13 includes a fuel pressure sensor for measuring fuel injection pressure. The detection result (output information) of the fuel pressure sensor is sent to the ECU 100.

[0051] A crank angle sensor 19 for detecting piston position is installed on the internal combustion engine ENG. The detection result (output information) of the crank angle sensor 19 is sent to the ECU 100.

[0052] The exhaust pipe 15 includes a three-way catalytic converter 10 for purifying exhaust gas and an air-fuel ratio sensor 9 for detecting the air-fuel ratio of the exhaust gas upstream of the three-way catalytic converter 10. Additionally, the internal combustion engine ENG includes a temperature sensor 18 for measuring the temperature of the cooling water surrounding the internal combustion engine ENG. The detection results (output information) from the air-fuel ratio sensor 9 and the temperature sensor 18 are sent to the ECU 100.

[0053] A throttle opening sensor 12 is installed on the accelerator pedal. The throttle opening sensor 12 detects the amount of pressure applied to the accelerator pedal, i.e., the throttle opening. The detection result (output information) of the throttle opening sensor 12 is sent to the ECU 100.

[0054] The ECU 100 calculates the required torque based on the output information from the throttle opening sensor 12. That is, the throttle opening sensor 12 can also be referred to as the required torque detection sensor for the internal combustion engine. Furthermore, the ECU 100 calculates the engine speed based on the output information from the crank angle sensor 19. Based on the engine's operating state obtained from the output information of various sensors, the ECU 100 appropriately calculates the main operating parameters of the internal combustion engine, such as airflow, fuel injection quantity, ignition timing, and fuel pressure.

[0055] The fuel injection quantity calculated by the ECU 100 is converted into a valve opening pulse signal and sent to the injector 13. Additionally, an ignition signal is sent to the ignition coil 16 to ensure ignition at the ignition timing calculated by the ECU 100. The throttle opening calculated by the ECU 100 is sent as a throttle actuation signal to the electronically controlled throttle 2.

[0056] Fuel is injected from injector 13 into the air flowing into cylinder block 14 from the intake manifold through the intake valve, thereby forming a mixture. The mixture is ignited (exploded) by a spark generated by spark plug 17 at a predetermined ignition timing. The combustion pressure generated by this ignition pushes down the piston, thereby driving the crankshaft (rotor shaft) connected to the piston via connecting rod, generating the driving force as an internal combustion engine (ENG).

[0057] Additionally, the exhaust gas after the explosion is sent to the three-way catalyst 10 via the exhaust pipe 15, where the exhaust components are purified and discharged to the outside. In the internal combustion engine ENG of this embodiment, a case of using variable valve timing control (VTC) that continuously adjusts the opening and closing timing of the intake valve according to the engine speed and load is illustrated.

[0058] Figure 2 This is a schematic diagram illustrating the hardware configuration of the ECU100, which serves as the control device for an internal combustion engine.

[0059] exist Figure 2 In this process, the following output information is input to the input circuit 21 of the ECU 100. Specifically, the input circuit 21 receives the airflow rate (intake air volume) from the airflow sensor 1 and the intake manifold pressure (intake pressure) from the intake pressure sensor 3. Additionally, although in Figure 2 Not shown in the figure, but the primary or secondary voltage of the voltage sensor from the ignition coil 16 is input to the input circuit 21.

[0060] Additionally, the input circuit 21 of the ECU 100 receives the following data: fuel injection pressure from the fuel pressure sensor of the fuel injection device 13, crank angle from the crank angle sensor 19, exhaust air-fuel ratio from the air-fuel ratio sensor 9, and coolant temperature from the temperature sensor 18. Furthermore, the input circuit 21 receives the following data: throttle opening from the throttle opening sensor 12, crankshaft speed, and various VTC settings.

[0061] The output information from these various sensors, etc., becomes the input information of ECU100. Furthermore, the input information input to ECU100 is not limited to these.

[0062] Input information input to the input circuit 21 of the ECU 100 is sent to the input port side within the input / output port 22. The input information sent to the input / output port 22 is temporarily stored in RAM (Random Access Memory) 23c and processed in the CPU 23a according to a predetermined control program. The CPU 23a is an arithmetic processing unit called the Central Processing Unit. The control program describing the arithmetic processing performed by the CPU 23a is pre-written into ROM (Read-Only Memory) 23b.

[0063] The output information indicating the amount of action of the fuel injection valve or ignition coil of the internal combustion engine calculated according to the control program is temporarily stored in RAM23c and then sent to the output port side of input / output port 22, and then to ignition control unit 24 or fuel injection control unit 25, etc. In addition, although the internal combustion engine ENG also uses actuators other than those described above, their description is omitted here.

[0064] In this embodiment, the ECU100, as a drive circuit, includes an ignition control unit 24 and a fuel injection control unit 25.

[0065] The ignition control unit 24 acquires information related to the energizing period and energizing time of the ignition coil 16 as an operating quantity of the associated actuator, and controls the energizing period and energizing time of the ignition coil 16 based on the acquired operating quantity.

[0066] The fuel injection control unit 25 acquires information related to the valve opening period and valve opening duration of the fuel injection device 13 as the operating quantity of the associated actuator, and controls the opening and closing of the valve for pressure adjustment of the fuel injection device 13, the valve opening period, and the pressure adjustment valve of the fuel pressure pump based on the acquired operating quantity.

[0067] Furthermore, in this embodiment, the ECU 100 is configured to include an ignition control unit 24 for controlling the energizing time and the amount of discharge energy to the ignition coil, and a fuel injection control unit 25 for controlling the injection period and injection time of the fuel injection device. However, this is only one example. That is, a portion of each control unit of the ignition control unit 24 and the fuel injection control unit 25 may also be installed on a device different from the ECU 100.

[0068] Figure 3 This is a schematic functional block diagram illustrating the intake metering control in the ECU100 of this embodiment.

[0069] Figure 3The intake air metering control shown is a program executed by CPU 23a in ECU 100. In this intake air metering control, the airflow sensor reading, engine speed, and coolant temperature are used as inputs to calculate the airflow into the cylinder. The intake manifold pressure estimation unit 301 calculates the intake manifold pressure based on the mass and energy conservation formulas within the volume from the throttle valve to the engine, and the gas state equation. Furthermore, the mass conservation formula, energy conservation formula, and gas state equation can be described as follows.

[0070] [Formula 1]

[0071]

[0072] [Equation 2]

[0073]

[0074] [Formula 3]

[0075]

[0076] [Formula 4]

[0077]

[0078] Here, Equation 1 is the mass preservation equation, Equation 2 is the energy preservation equation, and Equation 3 is the equation of state for the gas.

[0079] In these formulas, t represents time [s], m in The mass of gas in the intake manifold [kg], m atm The measured value (air flow rate) [kg / s] of the air flow sensor, m egr EGR flow rate [kg / s], m cyl The gas flow rate into the cylinder (gas flow rate into the cylinder) [kg / s].

[0080] In addition, in these formulas, e in It is the specific internal energy of the gas inside the intake manifold [J / kg], γ atm It is the specific heat ratio of the atmosphere [-], γ egr It is the specific heat ratio of EGR gas [-], γ in It is the specific heat ratio of the gas in the intake pipe [-], R atm It is the atmospheric gas constant [J / kg / K], R egr It is the gas constant of EGR gas [J / kg / K].

[0081] Furthermore, in these formulas, R in It is the gas constant of the gas in the intake manifold, expressed in J / kg / K, or T. atm It is atmospheric temperature [K], Tegr It is the EGR gas temperature [K], T in It is the gas temperature inside the intake manifold (intake manifold temperature), V in It is the intake manifold volume [m 3 ], α in Thermal conductivity [W / m] 2 / K],S in It is the area of ​​contact between the intake pipe and the gas [m²] 2 ], T wall It is the temperature of the intake manifold wall [K], P in It's the intake manifold pressure.

[0082] In addition, m atm m egr m cyl As shown in the various formulas, the actual expression is to assign [·] above m. In the following description, the [·] above m will also be omitted.

[0083] Specific heat ratio and gas constant are physical quantities that vary depending on the composition of the gas. Assuming the respective gas compositions, these can be determined by referring to experimental results and literature values. Thermal conductivity can also be calibrated through pre-conducted experiments. The EGR flow estimation unit 306 calculates the EGR flow rate, and the cylinder block inflow gas flow calculation unit 303 calculates the cylinder block inflow gas flow rate.

[0084] The EGR gas temperature can be approximated by the cooling water temperature passing through the EGR cooler, or determined by referring to a mapping experimentally determined in advance with operating conditions and cooling water temperature as the axis.

[0085] Equations [1] and [2] calculate the gas mass m in the intake pipe by performing numerical integration based on the values ​​assigned to the variables on the right side. in The internal energy e of the intake manifold in The formula.

[0086] Furthermore, by calculating the gas mass m in the intake pipe from [Equation 1]... in The specific internal energy e in the intake pipe, obtained from [Equation 2] in Substituting into [Equation 3], the gas temperature T is calculated. in By substituting them into [Equation 4], the intake manifold pressure P can be calculated. in .

[0087] The intake efficiency calculation unit 302 calculates the intake efficiency, which is an intermediate parameter for intake metering control.

[0088] Regarding the calculation method for intake efficiency, use Figure 4 Detailed explanations will be provided.

[0089] The cylinder block inflow gas flow calculation unit 303 calculates the gas flow rate into the engine cylinder block based on the estimated intake manifold pressure and intake efficiency. Furthermore, the cylinder block gas flow rate is calculated using the following formula [5].

[0090] [Formula 5]

[0091]

[0092] Here, η represents the intake efficiency [-], and N e V represents the rotational speed [rpm]. D Displacement per cylinder [m] 3 ], n cyl The number of cylinders is [-].

[0093] The cylinder block inflow airflow calculation unit 304 calculates the cylinder block inflow gas flow based on the cylinder block gas flow and the EGR rate. That is, the cylinder block inflow airflow calculation unit 304 uses the gas flow calculated by the cylinder block gas flow calculation unit 303 and the EGR rate calculated by the EGR distribution estimation unit 307 (described later) to calculate the airflow into the cylinder (cylinder block inflow airflow).

[0094] Specifically, the airflow into the cylinder is calculated using Equation 6 below.

[0095] [Formula 6]

[0096]

[0097] Here, m air It is the airflow rate into the cylinder [kg / s], y EGR The EGR rate [-] is calculated by the EGR distribution estimation unit 307.

[0098] The exhaust pressure estimation unit 305 estimates the exhaust pressure based on the gas flow rate and rotational speed in the cylinder. For example, the exhaust pressure estimation unit 305 generates a calibration mapping of exhaust pressure with the gas flow rate and rotational speed in the cylinder as axes based on experiments and simulations in advance, and uses this mapping to estimate the exhaust pressure.

[0099] The EGR flow estimation unit 306 calculates the estimated intake manifold pressure, the estimated exhaust pressure, and the EGR gas flow rate flowing into the intake manifold. For example, the EGR flow estimation unit 306 generates a mapping based on experiments and simulations, with the differential pressure between the estimated exhaust pressure and the estimated intake manifold pressure and the EGR valve opening as axes, and uses this mapping to estimate the EGR flow rate.

[0100] The EGR distribution estimation unit 307 estimates the distribution of EGR gas in the intake manifold based on the EGR gas flow rate and calculates the EGR rate of the gas flowing into the cylinder. First, the EGR rate is calculated using the following formula [7].

[0101] [Formula 7]

[0102]

[0103] Furthermore, the EGR distribution estimation unit 307, as a unit that estimates the distribution of EGR gas and calculates the EGR rate of the gas flowing into the cylinder, applies a first-order hysteresis filter to perform the calculation. For example, when calculating the EGR rate of the gas flowing into the cylinder, the EGR distribution estimation unit 307 can use the following [Equation 8] for calculation.

[0104] [Formula 8]

[0105]

[0106] Here, y EGR,d The EGR rate of the gas flowing into the cylinder is calculated by applying a first-order hysteresis filter [-], where Δt is the calculation period [s], and τ is the EGR rate of the gas flowing into the cylinder. EGR The delay time is [s]. In [Equation 8], the EGR rate y of the gas flowing into the cylinder is explicitly stated by applying a first-order hysteresis filter. EGR,d As a function of time, the value of time t+Δt (y EGR,d (t+Δt)) represents the value of y based on time t. EGR,d (t) and the EGR rate obtained from [Equation 7] are calculated.

[0107] In addition, the delay time τ EGR The flow rate depends on factors such as the length of piping from the EGR gas and air confluence to the engine block, and needs to be calibrated for each operating condition through engine testing or simulation. The airflow into the engine block is calculated using the process described above.

[0108] Figure 4 It means Figure 3 Functional block diagram of the processing content of the intake efficiency calculation unit 302.

[0109] The basic intake efficiency calculation unit 401 calculates the intake efficiency as a reference based on the estimated values ​​of engine speed and intake manifold pressure. In this embodiment, the intake efficiency is defined by the following [Equation 9].

[0110] [Formula 9]

[0111]

[0112] The intake efficiency η shown in [Equation 9] was calibrated through experiments and simulations under conditions where the engine had reached a steady state (steady-state conditions). For example, when the EGR flow rate is 0 and the engine is operating under steady-state conditions, the gas flow rate m into the cylinder block is... cyl The time average and the air flow rate (m) measured by the air flow sensorAFM The time average values ​​are consistent. Using this condition, the time average value of the airflow measured by the airflow sensor, obtained during the steady-state test, is substituted into the cylinder inflow gas flow rate (m). cyl It can calculate the baseline intake efficiency (basic intake efficiency).

[0113] The basic intake efficiency calculation unit 401 generates a mapping based on the calculated basic intake efficiency, with engine speed and intake manifold pressure as axes. During engine operation, the intake efficiency is calculated by retrieving estimated values ​​from this mapping based on engine speed and intake manifold pressure. Furthermore, this mapping is generated based on experimental results obtained under stable conditions, and therefore is generated from data measured when the combustion chamber wall temperature reaches a stable state.

[0114] Therefore, if the wall temperature is in a state different from the steady state (transitional state) during engine operation, the intake efficiency calculated by reference mapping will not be consistent with the intake efficiency during operation, resulting in an error in the calculated intake efficiency value. Consequently, the estimated intake manifold pressure will also be incorrect. In this embodiment, a wall temperature correction unit 402 is provided to correct the error in the calculated intake efficiency value when the engine is in a transitional state during operation.

[0115] The wall temperature correction unit 402 calculates a correction value for the intake efficiency, an intermediate parameter, based on physical quantities that change along with the combustion chamber wall temperature, i.e., wall temperature-related physical quantities, and determines whether the wall temperature is in a transitional state, and performs correction accordingly. The change in combustion chamber wall temperature can be one or both of an estimated value and a measured value.

[0116] The intake efficiency correction value K calculation unit 403 calculates the correction value for the intake efficiency, and the wall temperature transition determination unit 404 establishes a flag indicating whether the wall temperature is in a transition state. Next, the switching unit 405 selects the processing corresponding to the flag.

[0117] Figure 5 This is a flowchart showing the processing content of the wall temperature correction unit 402 of the intake efficiency calculation unit 302.

[0118] First, in step S501, the intake efficiency correction value K calculation unit 403 of the wall temperature correction unit 402 estimates a stable value for the wall temperature-related parameters. For example, when using the intake manifold pressure as a wall temperature-related parameter, the engine continues to operate under its normal operating conditions (torque, speed, etc.). Therefore, the wall temperature correction unit 402 can consider the intake manifold pressure when the wall temperature reaches a stable state as a stable value.

[0119] Next, in step S502, the intake efficiency correction value K calculation unit 403 of the wall temperature correction unit 402 calculates the intake efficiency correction value K according to the following formula 10.

[0120] [Formula 10]

[0121]

[0122] Here, C is the coefficient, F m These are the measured or estimated values ​​of wall temperature-related parameters during operation, F st These are the stable values ​​of the wall temperature-related parameters. The coefficient C is a value that varies in sign depending on its correlation with the wall temperature-related parameters.

[0123] If a physical quantity positively correlated with wall temperature (the physical quantity that increases when wall temperature increases) is used as the wall temperature-related parameter, then C is a negative value. Conversely, if a physical quantity negatively correlated with wall temperature (the physical quantity that decreases when wall temperature increases) is used as the wall temperature-related parameter, then C is a positive value.

[0124] Next, in step S503, the wall temperature transition determination unit 404 of the wall temperature correction unit 402 determines whether the wall temperature is in a transition state based on the following formula 11, that is, whether the wall temperature deviates from the stable temperature of the wall temperature.

[0125] [Equation 11]

[0126]

[0127] Here, 'e' is a coefficient set for transitional judgment, ideally 0. However, an appropriate value for 'e' should be chosen based on factors such as signal noise and vibration.

[0128] If the result is True (=transition) in step S503, the wall temperature correction unit 402 proceeds to step S504, determines that the wall temperature is in a transition state, and there is no need to change the intake efficiency correction value K, and ends the process.

[0129] If the determination in step S503 is False (=stable), the wall temperature correction unit 402 proceeds to step S505, changes the intake efficiency correction value K to 1, and ends the process.

[0130] Furthermore, steps S501 and S502 are processes performed by the intake efficiency correction value K calculation unit 403. Step S503 is a process performed by the wall temperature transition determination unit 404, and steps S504 and S505 are processes performed by the switching unit 405.

[0131] Next, we will explain the case where intake manifold pressure is used as a parameter related to wall temperature.

[0132] The intake manifold pressure is a physical quantity that increases with the increase of wall temperature, therefore C in [Equation 3] is set to a negative value. For example, if the value of C is set to -1, the modified formula becomes the following [Equation 12].

[0133] [Equation 12]

[0134]

[0135] Here, p in,m It is the measured value of the intake manifold pressure, p in,s It is the intake manifold pressure when the combustion chamber wall temperature reaches a stable value (stable intake manifold pressure).

[0136] Figure 6 is a schematic diagram of the mapping used to calculate the stable value of intake manifold pressure p_(in, st).

[0137] For example, such as Figure 6A As shown, the mapping is based on rotational speed and gas flow rate (air flow rate or the sum of air flow rate and EGR flow rate). In addition, as... Figure 6B As shown, mappings can also be based on axes such as engine speed, throttle opening, and EGR opening. Additionally, the intake manifold gas temperature can be set on each mapping axis. Furthermore, mappings using different axes can be switched depending on the conditions. These mappings are generated from data acquired by the engine under stable conditions.

[0138] Figure 7 This is a graph showing the time-varying value of the estimated intake manifold pressure when correcting intermediate parameters (intake efficiency) based on measured intake manifold pressure values. From... Figure 7 The values ​​above represent throttle opening, wall temperature, intake efficiency correction value, intake manifold pressure, and airflow, respectively. The horizontal axis represents time.

[0139] The wall temperature graph uses dashed lines to represent stable wall temperature values ​​and solid lines to represent measured values. The intake manifold pressure graph uses solid lines to represent measured values, dashed lines to represent estimated values ​​according to this application, single-dot dashed lines to represent estimated values ​​without correction (correction factor K is 1), and dashed lines to represent stable values.

[0140] The airflow graph uses dashed lines to represent stable values ​​and solid lines to represent measured values. The throttle opening graph shows that the throttle opening begins at time t0 and remains constant after time t1.

[0141] After the throttle opening becomes constant, at time t s The wall temperature reaches a stable value. From time t1 to t... s Between these intervals, due to the changes in engine output accompanying the changes in throttle opening, the wall temperature gradually increases.

[0142] At this point, the measured intake manifold pressure (solid line) gradually increases, while the measured airflow (solid line) gradually decreases. A difference arises between the measured intake manifold pressure and the stable intake manifold pressure (dashed line).

[0143] This difference is the correlation between the stable wall temperature value (dashed line) and the measured value (solid line).

[0144] When formula (12) is used to correct the intake efficiency, an intake efficiency correction value greater than 0 is calculated. As shown in the intake manifold pressure graph, the estimated intake manifold pressure (dashed line) of this embodiment (with correction) shows good agreement with the measured value.

[0145] On the other hand, without correcting for intake efficiency (not applicable to this embodiment), the estimated value (without correction) becomes the estimated result of the intake manifold pressure shown by the dashed line, and the error between it and the measured value increases.

[0146] Here, as a supplement, the derivation process of Equation

[12] is explained, illustrating how the difference between the measured and stable intake manifold pressure values ​​becomes apparent due to the influence of cylinder wall temperature. Intake efficiency is a function of intake manifold pressure, engine speed, and cylinder wall temperature.

[0147] [Equation 13]

[0148]

[0149] Here, η represents the intake efficiency, and p in For intake manifold pressure, N e T is the engine speed. w Let be the combustion chamber wall temperature. Assuming the combustion chamber wall temperature is close to a steady-state temperature, perform a Taylor expansion on the right side.

[0150] [Formula 14]

[0151]

[0152] [Formula 15]

[0153]

[0154] Here, T w s t This is the stable value of the cylinder wall temperature. Since the change in the gas temperature inside the cylinder, which accompanies the change in cylinder wall temperature, causes a change in intake efficiency, the intake efficiency can be considered a function of the gas temperature inside the cylinder, thus requiring further transformation of the formula.

[0155] [Formula 16]

[0156]

[0157] Here, Tcyl It is the gas temperature inside the engine cylinder [K]. Furthermore, Equation 16 is transformed to be a function of the gas temperature inside the engine cylinder.

[0158] [Equation 17]

[0159]

[0160] Here, a partial differential equation relating the cylinder gas temperature to intake efficiency is derived. [Equation 17] is derived by expressing the amount of gas drawn into the cylinder in two ways. The amount of gas drawn into one combustion cycle is calculated by multiplying [Equation 1] by the time of one combustion cycle (2 engine revolutions).

[0161] [Formula 18]

[0162]

[0163] Here, M 1cyc It is the amount of gas drawn in during a combustion cycle [kg], R is the gas constant [J / kg / K], and T is the amount of gas drawn in during a combustion cycle. in It is the gas temperature [K] in the intake manifold, V D The displacement of a cylinder [m] 3 ], n cyl It is the number of cylinders [-].

[0164] Furthermore, assuming that the pressure in the cylinder during the intake valve closing period (IVC) is equal to the intake manifold pressure, and the temperature in the cylinder is equal to the gas temperature in the intake manifold, the amount of gas entering a cylinder at the moment the intake valve closes can be calculated using the following [Equation 19].

[0165] [Formula 19]

[0166]

[0167] Here, M cyl,gas It is the amount of gas in the cylinder when the intake valve is closed [kg], V IVC This is the cylinder volume when the intake valves are closed. The total volume, M, is equivalent to the number of cylinders. cyl,air The obtained value is the amount of gas drawn in during a combustion cycle, compared with M. 1cyc equal.

[0168] Therefore, by setting the product of [Equation 18] and the number of cylinders of the engine to be equal to [Equation 19], and rearranging it as the formula for intake efficiency, we obtain the following [Equation 20].

[0169] [Formula 20]

[0170]

[0171] By differentiating both sides of equation (20) with respect to the gas temperature inside the cylinder, we obtain the partial derivative [Equation 21] which is related to the gas temperature inside the cylinder and the intake efficiency.

[0172] [Equation 21]

[0173]

[0174] The intake efficiency modification formula of [Equation 22] is obtained from [Equation 17] and [Equation 21].

[0175] [Equation 22]

[0176]

[0177] [Equation 23]

[0178]

[0179] Here, T cyl,st This is the gas temperature inside the cylinder under stable cylinder wall temperature conditions [K]. Next, if we differentiate [Equation 19] under the condition of constant mass inside the cylinder, the relationship between the gas temperature inside the cylinder and the intake manifold pressure is obtained as shown in [Equation 24].

[0180] [Equation 24]

[0181]

[0182] Furthermore, as shown in Equation 25 below, the variation δ of the intake manifold pressure is determined. pin .

[0183] [Equation 25]

[0184]

[0185] If this decision is made, then Equation

[23] can be transformed as in Equation

[26] , and it can be seen that the intake efficiency correction amount is related to the change in intake manifold pressure.

[0186] [Equation 26]

[0187]

[0188] Thus, the intake efficiency correction formula is not simply derived from the correlation of phenomena. Although some approximations are required, it is a relationship derived based on physical formulas and is not equivalent to a simple combination.

[0189] Next, we will explain the case where airflow is used as a parameter related to wall temperature.

[0190] Airflow is a physical quantity that decreases as wall temperature increases, therefore C in [Equation 3] is set to a positive value. For example, if it is set to 1, the modified equation becomes [Equation 27] below.

[0191] [Equation 27]

[0192]

[0193] Here, m m This is the measured airflow rate, in meters (m). st It is the stable value of airflow.

[0194] Figure 8 shows the calculation of the stable value of airflow m. st A schematic diagram of the mapping. For example, such as... Figure 8A The diagram shows a mapping with engine speed and throttle opening as axes. In addition, as shown... Figure 8B As shown, mappings can also be based on axes such as engine speed and intake manifold pressure. Furthermore, the intake manifold gas temperature can be set on each mapping axis. Moreover, mappings using different axes can be switched depending on conditions. These mappings are generated from data acquired by the engine under stable conditions. Additionally, in reference... Figure 8B When mapping the data, the measured value of the intake manifold pressure is used.

[0195] Figure 9 This is a graph showing the time-varying value of the estimated intake manifold pressure when adjusting intermediate parameters (intake efficiency) based on measured airflow values. Figure 7 Similarly, the top and bottom axes represent throttle opening, wall temperature, intake efficiency correction value, intake manifold pressure, and airflow, respectively. The horizontal axis represents time.

[0196] The wall temperature graph uses dashed lines to represent stable wall temperature values ​​and solid lines to represent measured values. The intake manifold pressure graph uses solid lines to represent measured values, dashed lines to represent estimated values ​​of this application, and single-dot dashed lines to represent estimated values ​​without correction (correction factor K is 1).

[0197] The airflow graph uses dashed lines to represent stable values ​​and solid lines to represent measured values. The throttle opening graph shows that the throttle opening begins at time t0, and remains constant after time t1. After the throttle opening becomes constant, at time t... s The wall temperature reaches a stable value. From time t1 to t... s As the engine output changes with the throttle opening, the wall temperature gradually increases. At this point, a difference will occur between the measured airflow value (solid line) and the stable airflow value (dashed line). This difference is related to the difference between the stable wall temperature value (dashed line) and the measured value (solid line).

[0198] By calculating the intake efficiency correction value using Equation 27, it can be seen that the estimated intake manifold pressure (dashed line) in this embodiment (with correction) is in good agreement with the measured value. On the other hand, without correcting the intake efficiency, the estimated intake manifold pressure (without correction) becomes the estimated result of the intake manifold pressure shown by the dashed line, and the error between it and the measured value increases.

[0199] Next, we will explain the case where gas flow rate is used as a parameter related to wall temperature.

[0200] Since the gas flow rate is a physical quantity that decreases as the wall temperature increases, C in Equation [3] is set to a positive value. For example, the gas flow rate can be set to 1, and the modification is shown in Equation

[28] below.

[0201] [Equation 28]

[0202]

[0203] Here, m g,m It is the gas flow rate during operation, m g,st This is the stable value of the gas flow rate. The gas flow rate is the flow rate of air and EGR gas. In a system equipped with a flow meter that measures the EGR gas flow rate, it can be given as a measured value. However, in the absence of a flow meter that measures the EGR gas flow rate, it needs to be estimated based on the inlet pipe pressure, exhaust pressure, and EGR valve opening.

[0204] For example, by pre-creating a calibration mapping of the stable EGR gas flow rate based on the difference between the intake manifold pressure and the exhaust pressure, and the EGR valve opening, estimations can be made during operation based on this mapping.

[0205] Figure 10 shows the calculation of the stable value of gas flow rate m. g,st A schematic diagram of the mapping.

[0206] For example, such as Figure 10A As shown, the mapping can be performed with engine speed, throttle opening, and EGR valve opening as axes. Furthermore, as... Figure 10B As shown, mappings can also be based on engine speed and intake manifold pressure as axes. Furthermore, the intake manifold gas temperature can be set on each mapping axis. Further, mappings using different axes can be switched depending on conditions. These mappings are generated from data acquired by the engine under stable conditions. Additionally, refer to... Figure 10B At that time, the measured value of the intake manifold pressure is used.

[0207] Figure 11 This is a graph showing the time-varying value of the estimated intake manifold pressure when the intermediate parameter (intake efficiency) is corrected based on the estimated gas flow rate. Figure 7 and Figure 9 same,Figure 11 The graph shows, in order, throttle opening, wall temperature, intake efficiency correction value, intake manifold pressure, and gas flow rate. The wall temperature graph uses dashed lines to represent stable wall temperature values ​​and solid lines to represent measured values. The intake manifold pressure graph uses solid lines to represent measured values, dashed lines to represent the estimated values ​​of this application, and single-dot lines to represent the estimated values ​​without correction (correction factor K = 1). The gas flow rate graph uses dashed lines to represent stable values ​​and solid lines to represent measured or estimated values.

[0208] The throttle opening diagram shows that the throttle opening starts at time t0 and remains constant after time t1.

[0209] After the throttle opening becomes constant, at time t s The wall temperature reaches a stable value. From time t1 to t... s During this period, due to the changes in engine output accompanying the changes in throttle opening, the wall temperature gradually increases. At this time, the measured or estimated value of gas flow will differ from the stable value of gas flow (dashed line). This difference is related to the difference between the stable value of wall temperature (dashed line) and the measured value (solid line).

[0210] Thus, by calculating the intake efficiency correction value using Equation 28, the estimated intake manifold pressure (dashed line) of this embodiment (with correction) shows good agreement with the measured value. On the other hand, without correction for intake efficiency, i.e. without correction, the estimated intake manifold pressure shown as a single-dot line has a larger error compared with the measured value shown as a solid line.

[0211] As described above, by using the estimated or measured values ​​of physical quantities that change with the temperature of the combustion chamber wall, the intake efficiency can be corrected using data obtained under steady-state conditions and a simple correction method. As a result, the correction can be achieved while suppressing the calibration time.

[0212] (Second Implementation Example)

[0213] Below, refer to Figures 12-15 The second embodiment of the present invention will be described. Furthermore, in this embodiment, the system configuration of the internal combustion engine, the hardware configuration of the ECU, and the intake air metering control processing example are respectively described in the first embodiment through… Figures 1-3 The explanation should be structured without repeating details.

[0214] Figure 12 This is a functional block diagram representing the processing content of the intake efficiency calculation unit 302.

[0215] The basic intake efficiency calculation unit 1201 is a processing unit that calculates a baseline intake efficiency based on an estimated value of engine speed or intake manifold pressure. The baseline intake efficiency is mapped along the axes of engine speed and intake manifold pressure; during operation, the estimated values ​​are retrieved and calculated based on these values. Furthermore, this mapping is suitable for data measured when the combustion chamber wall temperature has reached a stable state.

[0216] The wall temperature correction unit 1202 calculates a correction value for the intake efficiency, an intermediate parameter, based on the difference between the stable value of the wall temperature and the wall temperature during operation, which is a physical quantity that changes with the combustion chamber wall temperature. Then, the wall temperature correction unit 1202 determines whether the wall temperature is in a transitional state and makes corrections accordingly.

[0217] The wall temperature difference calculation unit 1203 calculates the difference between the stable value of the wall surface temperature and the wall surface temperature during operation (the difference from the stable temperature).

[0218] The intake efficiency correction value K calculation unit 1204 calculates the intake efficiency correction value based on the difference from the stable temperature.

[0219] The wall temperature transition determination unit 1205 establishes a flag indicating whether the wall temperature is in a transition state.

[0220] The switch unit 1206 performs selection processing based on the flag established by the wall temperature transition determination unit 1205.

[0221] Figure 13 This is a flowchart showing the processing content of the wall temperature correction unit 1202 of the intake efficiency calculation unit 302.

[0222] First, the wall temperature correction unit 1202 estimates the stable value of the wall temperature in step S1301.

[0223] Next, in step S1302, the wall temperature difference calculation unit 1203 calculates the difference from the stable wall temperature value as shown in [Equation 29].

[0224] [Equation 29]

[0225]

[0226] Here, T is corrected. w It is the measured or estimated value of the wall temperature, T. w,st This is the stable wall temperature value.

[0227] Next, in step S1303, the intake efficiency correction value K calculation unit 1204 calculates the intake efficiency correction value K as shown in [Equation 30].

[0228] [Formula 30]

[0229]

[0230] Here, T in It refers to the gas temperature in the intake manifold; any measured or estimated value will suffice.

[0231] Alternatively, Equation

[30] can also be derived in the following order.

[0232] When the temperature of the air drawn into the engine cylinder changes due to heat transfer from the cylinder wall surface, the energy storage formula is given by the following equation.

[0233] [Equation 31]

[0234]

[0235] Here, c p It is the constant pressure specific heat [J / kg / K], h tr Thermal conductivity [W / m] 2 / K],S cyl It is the cylinder block wall area [m 2 If we integrate equation

[31] with respect to all gas temperatures except the gas temperature inside the cylinder as a constant, and take the initial value as the gas temperature T in the intake manifold... in Then we get the formula for the gas temperature inside the cylinder as shown in [Equation 32].

[0236] [Equation 32]

[0237]

[0238] [Equation 33]

[0239]

[0240] Here, α can be calculated based on operating conditions and various detection values, or it can be assigned an approximate value. For example, a trial calculation could be a value of approximately 0.5 to 1.

[0241] Next, if we differentiate [Equation 32], we obtain [Equation 34], which is a partial derivative related to the cylinder wall temperature and the gas temperature inside the cylinder.

[0242] [Formula 34]

[0243]

[0244] From Equations 16, 33, and 34, we obtain Equation 35.

[0245] [Formula 35]

[0246]

[0247] Therefore, the intake efficiency correction K is given by the following formula [Equation 36].

[0248] [Formula 36]

[0249]

[0250] Thus, the intake efficiency correction K is not derived for simple combination, but is calculated based on the formula governing the physical phenomenon.

[0251] In step S1304, the wall temperature transition determination unit 1205 determines whether the wall temperature is in a transition state based on the following [Equation 37].

[0252] [Formula 37]

[0253]

[0254] Here, 'e' is a coefficient set for transitional judgment, ideally 0. However, an appropriate value for 'e' needs to be selected based on factors such as signal noise and vibration.

[0255] Next, if the result is True (=transition) in step S1304, proceed to step S1305. The switching unit 1206 determines that the wall temperature is in a transition state and no change to the correction value K is required, and the process ends.

[0256] If the condition is determined to be Flase (stable) in step S1304, proceed to step S1306, where the switch unit 1206 changes the correction value K to 1 and ends the process.

[0257] Figure 14 This is a schematic diagram of a mapping used to calculate the stable wall temperature. For example, the mapping could be based on engine speed and gas flow rate as axes. This mapping is generated from data acquired by the engine under steady-state conditions.

[0258] Figure 15 It is a graph showing the time change of the estimated intake manifold pressure when the intermediate parameter (intake efficiency) is corrected based on the difference between the estimated wall temperature and the stable wall temperature (the difference from the stable temperature). Figure 15 The parameters, from top to bottom, represent throttle opening, wall temperature, intake efficiency correction value, intake manifold pressure, and gas flow rate. The horizontal axis represents time.

[0259] The wall temperature graph uses dashed lines to represent stable wall temperature values ​​and solid lines to represent measured values. The intake manifold pressure graph uses solid lines to represent measured values, dashed lines to represent estimated values ​​of this application, and single-dot dashed lines to represent estimated values ​​without correction (correction factor K is 1).

[0260] The gas flow rate graph uses solid lines to represent measured or estimated values. The throttle opening graph shows that the throttle opens from time t0, and remains constant after time t1. After the throttle opening becomes constant, at time t... s The wall temperature reaches a stable value. From time t1 to t... s During this period, the wall temperature gradually increases due to the changes in engine output accompanying the changes in throttle opening. Of course, during this period, the wall temperature differs from the stable wall temperature. If we focus on this difference, we find that it can be easily corrected using a model formula, and the derived formula is [Equation 36].

[0261] According to this embodiment, the intake efficiency correction value is appropriately calculated using Equation 36, and the estimated intake manifold pressure (dashed line) shows good agreement with the measured value. On the other hand, it can be seen that without correction for intake efficiency, i.e. without correction, the estimated intake manifold pressure shown as a single-dot line has a larger error compared with the measured value.

[0262] As described above, according to the second embodiment, by using the difference with the stable value of the wall temperature, it is possible to correct the intake efficiency without having a mapping of the intermediate parameter (intake efficiency) relative to the wall temperature.

[0263] (Third implementation method)

[0264] Below, refer to Figures 16-17 The third embodiment of the present invention will be described. Furthermore, in this embodiment, the system configuration of the internal combustion engine, the hardware configuration of the ECU, and the intake air metering control processing example are respectively utilized in the first embodiment. Figures 1-3 The structure is explained. Furthermore, the processing configuration of the intake efficiency calculation unit is as described in the first embodiment. Figure 4 The configuration described herein, and the mapping used to calculate the stable intake manifold pressure value, are applicable to the mapping illustrated in FIG6 in the first embodiment. Repeated descriptions of the configuration and processing of these first embodiments are omitted.

[0265] Figure 16 It means Figure 4 A flowchart showing the processing of the wall temperature correction unit 402 in the intake efficiency calculation unit 302.

[0266] First, in step S1601, the intake efficiency correction value K calculation unit 403 of the wall temperature correction unit 402 estimates the stable value of the intake manifold pressure. This estimation can be performed using the relationship shown in Figure 6. Next, in step S1602, the intake efficiency correction value K calculation unit 403 calculates the intake efficiency correction value K based on the following formula.

[0267] [Formula 38]

[0268]

[0269] Where C is the coefficient, p in,e This is the estimated value of the intake manifold pressure. Coefficients C and D are negative real numbers. For example, C can be set to -1, and D can be set to -2, etc. Coefficients C and D can also be other settings. In addition, the second term on the right side of [Equation 38] is a term that corrects for the difference between the actual engine wall temperature and the steady-state wall temperature, and the third term on the right side of [Equation 38] is a term that corrects for the difference between the engine wall temperature and the steady-state wall temperature, which is not explicitly reflected in the intake metering control but is implicitly identified in the calculation.

[0270] Next, in step S1603, the wall temperature transition determination unit 404 determines whether the wall temperature is in a transition state based on the following formula, that is, whether the wall temperature deviates from the stable temperature of the wall.

[0271] [Formula 39]

[0272]

[0273] Here, 'e' is a coefficient set for transitional judgment, ideally 0. However, an appropriate value for 'e' needs to be selected based on factors such as signal noise and vibration.

[0274] If the result is True (=transition) in step S1603, proceed to step S1604. The switching unit 405 determines that the wall temperature is in a transition state and does not need to change the correction value K, and ends the process.

[0275] If the determination in step S1603 is False (=stable), proceed to step S1605, where the switch unit 405 changes the correction value K to 1 and ends the process.

[0276] In addition, steps S1601 and S1602 are... Figure 4 The process implemented by the intake efficiency correction value K calculation unit 403, step S1603 is... Figure 4 The processing of the wall temperature transition determination section 404, steps S1604 and S1605 are Figure 4 The processing of the switch section 405.

[0277] Figure 17 It is a graph showing the time change of the estimated intake manifold pressure when the intermediate parameter (intake efficiency) is corrected based on the measured intake manifold pressure value and the estimated intake manifold pressure value. Figure 17 The data displayed from top to bottom are throttle opening, wall temperature, intake efficiency correction value, intake manifold pressure, and airflow. The horizontal axis represents time.

[0278] The wall temperature graph uses dashed lines to represent stable wall temperature values ​​and solid lines to represent measured values. The intake manifold pressure graph uses solid lines to represent measured values, dashed lines to represent the estimated values ​​of this application, and single-dot dashed lines to represent the estimated values ​​without correction (correction factor K = 1), with dashed lines representing stable values. The airflow graph uses dashed lines to represent stable values ​​and solid lines to represent measured values.

[0279] Figure 17 The example illustrates the case where the throttle opening begins at time t0 and remains constant after time t1. After the throttle opening becomes constant, at time t... s The wall temperature reaches a stable value. From time t1 to t... s During this period, due to the changes in engine output accompanying the changes in throttle opening, the wall temperature gradually increases. At this time, the measured intake manifold pressure (solid line) gradually increases, while the measured airflow (solid line) gradually decreases. A difference will occur between the measured intake manifold pressure and the stable intake manifold pressure (dashed line). This difference is related to the difference between the stable wall temperature (dashed line) and the measured value (solid line).

[0280] By using Equation 38, the intake efficiency correction value is calculated to be greater than 0. The estimated intake manifold pressure (dashed line) in this embodiment (with correction) shows good agreement with the measured value. Furthermore, near time t1, a difference arises between the estimated and measured values. However, according to Equation 38, since the error between the wall temperature implicitly identified by the intake metering control and the wall temperature during operation is corrected, the time variation moves in the direction where the estimated and measured values ​​are consistent. On the other hand, without correcting for the intake efficiency, the estimated intake manifold pressure, shown as a single-dotted line, shows the error.

[0281] Therefore, according to the third embodiment, the intake efficiency can also be corrected by using data obtained under stable conditions and a simple correction procedure, and as a result, the correction can be achieved by suppressing the calibration time.

[0282] <Variation Example>

[0283] Furthermore, the embodiments described so far have been detailed for the purpose of easily understanding the present invention and are not necessarily limited to having all the described configurations. Additionally, some or all of the configurations or processes described in one embodiment may be combined with other embodiments.

[0284] Furthermore, in the block diagrams, control lines and information lines only represent lines deemed necessary for the description; they may not represent all control lines and information lines on the product. In reality, almost all components can be considered interconnected.

[0285] In addition, the process shown in each flowchart is also an example. If the processing results are the same, some processing order can be changed or multiple processes can be executed simultaneously.

[0286] Furthermore, in each embodiment, when calculating the physical quantity during the process of obtaining the correction value in the wall temperature correction unit, an estimated value or a measured value of that physical quantity is obtained. Alternatively, both the estimated value and the measured value of the physical quantity can be obtained, and corrections can be made based on both values.

[0287] For example, a physical quantity that changes with the temperature of the combustion chamber wall inside an internal combustion engine cylinder can be corrected based on one or both of the estimated or measured values.

[0288] In addition, for example, the stable intake manifold pressure value can be calculated based on one or both of the following: throttle opening, EGR valve opening, measured value of air flow sensor, measured or estimated value of EGR flow, engine speed, and measured or estimated value of intake manifold temperature.

[0289] In addition, physical quantities that change with the temperature of the combustion chamber wall can be calculated based on one or both of the measured values ​​of the air flow sensor, the measured or estimated values ​​of the gas flow, or the measured or estimated values ​​of the gas temperature in the intake manifold.

[0290] Furthermore, the correction value of the intermediate parameter can be calculated based on one or both of the reference value of the gas temperature in the intake manifold and the measured or estimated value of the gas temperature in the intake manifold.

[0291] Furthermore, such as Figure 2 As described above, the control device 100 is configured as a computer equipped with a CPU and memory, and installs a program that executes the processing described in each embodiment, thereby functioning as a control device. Configuring it as such a computer is one example; however, some or all of the functions performed by the control device 100 can also be implemented using hardware such as a FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0292] In addition, when the control device 100 is configured with a computer, the programs installed on the computer can be prepared in the memory within the control device 100, or they can be stored in external memory, IC card, SD card, optical disc, or other recording media for transmission.

[0293] Explanation of symbols

[0294] 1…Air flow sensor, 2…Electronic throttle control, 3…Intake pressure sensor, 5…Variable valve, 9…Air-fuel ratio sensor, 10…Three-way catalytic converter, 12…Throttle opening sensor, 13…Fuel injection device (injector), 14…Cylinder block, 15…Exhaust pipe, 16…Ignition coil, 17…Spark plug, 18…Temperature sensor, 19…Crank angle sensor, 20…Fuel injection system, 20a…Fuel pump, 21…Input circuit, 22…Input / output port, 23a…CPU, 23b…ROM, 23c…RAM, 24…Ignition control unit, 25…Fuel injection control unit, 100…ECU, 301…Intake manifold pressure estimation unit, 302…Intake… 303… Intake efficiency calculation unit, 304… Cylinder block inflow gas flow calculation unit, 305… Cylinder block flow air flow calculation unit, 306… Exhaust pressure estimation unit, 307… EGR flow estimation unit, 401… EGR distribution estimation unit, 402… Basic intake efficiency calculation unit, 403… Wall temperature correction unit, 404… Intake efficiency correction value K calculation unit, 405… Wall temperature transition determination unit, 1201… Basic intake efficiency calculation unit, 1202… Wall temperature correction unit, 1203… Wall temperature difference calculation unit, 1204… Intake efficiency correction value K calculation unit, 1205… Wall temperature transition determination unit, 1206… Switch unit, ENG… Internal combustion engine (engine).

Claims

1. A control device for an internal combustion engine, comprising an in-cylinder air volume calculation unit that calculates the amount of air entering the cylinder of the internal combustion engine based on an air flow sensor, characterized in that... It includes a calculation unit that, based on the intake manifold pressure, calculates intermediate parameters representing intake efficiency used to calculate the amount of air flowing into the cylinder. The intermediate parameters are corrected based on one or both of the estimated or measured values ​​of a physical quantity that changes with the temperature of the combustion chamber wall inside the internal combustion engine cylinder.

2. The control device for an internal combustion engine according to claim 1, characterized in that, The physical quantity that changes with the temperature of the combustion chamber wall is the intake manifold pressure.

3. The control device for an internal combustion engine according to claim 2, characterized in that, The calculation unit for calculating the intermediate parameters includes a unit for estimating the intake manifold pressure when the combustion chamber wall temperature reaches a stable state, i.e., the stable value of the intake manifold pressure. The estimation unit for the stable intake manifold pressure value calculates the correction value of the intermediate parameter based on the stable intake manifold pressure value and the estimated intake manifold pressure value or the intake manifold pressure gauge measurement value.

4. The control device for an internal combustion engine according to claim 2, characterized in that, The calculation unit that calculates the intermediate parameters calculates the correction value of the intermediate parameters based on the measured value of the intake manifold pressure and the estimated value of the intake manifold pressure.

5. The control device for an internal combustion engine according to claim 3, characterized in that, The stable intake manifold pressure value is calculated based on the throttle opening, EGR valve opening, measured values ​​from the air flow sensor, measured or estimated values ​​of EGR flow, engine speed, and measured or estimated values ​​of intake manifold temperature.

6. The control device for an internal combustion engine according to claim 1, characterized in that, The physical quantity that changes with the temperature of the combustion chamber wall is the measured value of the air flow sensor, or the measured or estimated value of the gas flow.

7. The control device for an internal combustion engine according to claim 6, characterized in that, The calculation unit for calculating the correction value of the intermediate parameter includes an estimation unit for the air flow rate (i.e., the stable air flow rate value) when the combustion chamber wall temperature reaches a stable state, or the gas flow rate (i.e., the stable gas flow rate value) when the combustion chamber wall temperature reaches a stable state. The estimation unit for the stable gas flow rate calculates a correction value for the intermediate parameter based on the stable air flow rate or the stable gas flow rate and the measured air flow rate.

8. The control device for an internal combustion engine according to claim 7, characterized in that, The stable airflow value or the stable gasflow value is calculated based on the throttle opening and engine speed.

9. The control device for an internal combustion engine according to claim 1, characterized in that, The physical quantity that changes with the temperature of the combustion chamber wall is the measured or estimated value of the gas temperature in the intake manifold.

10. The control device for an internal combustion engine according to claim 7, characterized in that, The correction value of the intermediate parameter is calculated based on the reference value of the gas temperature in the intake pipe and the measured or estimated value of the gas temperature in the intake pipe.

11. The control device for an internal combustion engine according to claim 10, characterized in that, The reference value for the gas temperature in the intake manifold is calculated based on the throttle opening, EGR valve opening, and engine speed.

12. The control device for an internal combustion engine according to claim 1, characterized in that, It includes a calculation unit that calculates the difference between the cylinder wall temperature and the baseline state based on the throttle opening and engine speed. The physical quantity that changes with the temperature of the combustion chamber wall is the difference between the temperature of the cylinder wall and the temperature under reference conditions.

13. The control device for an internal combustion engine according to claim 1, characterized in that, The calculation unit for calculating the correction value of the intermediate parameters includes a unit for estimating the wall temperature when the combustion chamber wall temperature reaches a stable state, i.e., the stable value of the wall temperature. The estimation unit for the stable wall temperature calculates the correction value of the intermediate parameter based on the difference between the wall temperature and the combustion chamber wall temperature.

14. A control method for an internal combustion engine, comprising calculating the in-cylinder air volume based on an air flow sensor, wherein the in-cylinder air volume is calculated. The system performs calculations based on intake manifold pressure to determine intermediate parameters representing intake efficiency used to calculate the amount of air flowing into the cylinder. The intermediate parameters are corrected based on one or both of the estimated or measured values ​​of a physical quantity that changes with the temperature of the combustion chamber wall within the internal combustion engine cylinder.

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