WO2024116331A1

WO2024116331A1 - Control device and control method for internal combustion engine

Info

Publication number: WO2024116331A1
Application number: PCT/JP2022/044202
Authority: WO
Inventors: 広人石川; 伸也眞戸原
Original assignee: 日立Astemo株式会社
Priority date: 2022-11-30
Filing date: 2022-11-30
Publication date: 2024-06-06

Abstract

Provided is a control device 100 for an internal combustion engine that controls the internal combustion engine using a flow rate detection value from an airflow sensor that detects the air intake rate of the internal combustion engine, said control device comprising: an operational control unit 120, a ripple factor prediction unit 130, a permissible ripple factor output unit 140, and a limit target value output unit 110. The operational control unit 120 controls the operational state of the internal combustion engine on the basis of a control target value CTV of the internal combustion engine. The ripple factor prediction unit 130 outputs a predicted ripple factor PRe that predicts the ripple factor of the flow rate detection value on the basis of the control target value CTV. The permissible ripple factor output unit 140 outputs a permissible ripple factor PRa on the basis of a rotational speed ES that serves as the operational state of the internal combustion engine. If the predicted ripple factor PRe exceeds the permissible ripple factor PRa, the limit target value output unit 110 outputs a limit target value CTVr produced by changing the control target value CTV so as to lower the ripple factor. If the limit target value CTVr has been input, the limit target value output unit 110 controls the operational state of the internal combustion engine on the basis of the limit target value CTVr.

Description

Control device and control method for internal combustion engine

This disclosure relates to a control device and control method for an internal combustion engine.

　Inventions relating to engine control devices that control spark ignition internal combustion engines are known. For example, the conventional engine control device described in Patent Document 1 below controls an internal combustion engine that has a fuel injection device that supplies fuel to the cylinders and a throttle valve arranged in the intake passage.

This conventional engine control device includes a processor, an airflow sensor that is disposed in the intake passage upstream of the throttle valve and detects the intake air flow rate, and a throttle position sensor that detects the throttle opening of the throttle valve. The fuel injection control executed by the processor includes a first fuel injection process and a second fuel injection process.

In the first fuel injection process, the fuel injection device is controlled to inject an amount of fuel corresponding to a first intake air amount based on the intake air flow rate detected by the airflow sensor. In the second fuel injection process, the fuel injection device is controlled to inject an amount of fuel corresponding to a second intake air amount based on the throttle opening detected by the throttle position sensor.

The processor selects the first fuel injection process when the pulsation rate, which is the rate of change of the pulsation of the intake air flow rate detected by the air flow sensor, is equal to or lower than the pulsation rate threshold, and selects the second fuel injection process when the pulsation rate is higher than the pulsation rate threshold. The pulsation rate threshold is smaller when the temperature correlation value, which correlates with the temperature of the internal combustion engine, is low than when the temperature correlation value is high (Patent Document 1, paragraph 0008, claim 1, abstract, etc.).

JP 2021-076040 A

As described above, in the above conventional engine control device, when the intake air flow pulsation rate is higher than the pulsation rate threshold, a second fuel injection process is selected to inject an amount of fuel corresponding to a second intake air amount based on the throttle opening. Even when the second fuel injection process is selected in this conventional engine control device, a control is being considered in which a pulsation correction value is calculated to correct the intake air flow rate detection value by the airflow sensor, and an amount of fuel is injected corresponding to the corrected flow rate detection value.

The pulsation correction value is determined, for example, as follows: The internal combustion engine is operated under reference conditions within a specified temperature range, and when pulsation of the intake air occurs, the intake air volume is detected by the airflow sensor, and the intake air volume is calculated based on the operating conditions, such as the internal combustion engine speed, throttle opening, and exhaust components. The pulsation correction value is then determined so that the intake air volume detected by the airflow sensor matches the intake air volume calculated based on the operating conditions.

However, for example, at extremely low temperatures that deviate from the above-mentioned standard conditions, the resonant frequency of the intake air decreases, and the peak of the intake air pulsation rate shifts to the lower rotation speed side of the internal combustion engine. As a result, the relationship between the internal combustion engine rotation speed and the intake air pulsation rate falls outside the range for which the above-mentioned pulsation correction value is determined, making it impossible to correct the flow detection value of the airflow sensor, and there is a risk of deterioration in the operating performance of the internal combustion engine and exhaust components.

The present disclosure provides an internal combustion engine control device and control method that can prevent the relationship between the engine speed and the pulsation rate of the intake air from falling outside the range for which the pulsation correction value is determined, thereby preventing deterioration of the engine's operating performance and exhaust components.

One aspect of the present disclosure is a control device for an internal combustion engine that controls the internal combustion engine using a flow rate detection value of an air flow sensor that detects the amount of intake air into the internal combustion engine, and includes an operation control unit that controls the operating state of the internal combustion engine based on a control target value of the internal combustion engine, a pulsation rate prediction unit that outputs a predicted pulsation rate that predicts the pulsation rate of the flow rate detection value based on the control target value, an allowable pulsation rate output unit that outputs an allowable pulsation rate that is the maximum value of the pulsation rate that is allowable based on the operating state of the internal combustion engine, and a restriction target value output unit that outputs a restriction target value that changes the control target value so as to reduce the pulsation rate when the predicted pulsation rate exceeds the allowable pulsation rate, and the operation control unit controls the operating state of the internal combustion engine based on the restriction target value when the restriction target value is input.

According to one aspect of the present disclosure, it is possible to provide a control device for an internal combustion engine that can prevent the relationship between the rotation speed of the internal combustion engine and the pulsation rate of the intake air from going outside the range for which the pulsation correction value is determined, thereby preventing deterioration of the operating performance of the internal combustion engine and exhaust components.

1 is a schematic diagram showing a first embodiment of a control device for an internal combustion engine according to the present disclosure; FIG. 2 is a functional block diagram of the control device for the internal combustion engine of FIG. 1 . 3 is a block diagram showing details of a pulsation rate prediction unit and a permissible pulsation rate output unit in FIG. 2 . 3 is a flow diagram showing a control method using the control device for the internal combustion engine of FIG. 2; 5 is a graph showing the relationship between the rotation speed of an internal combustion engine and the pulsation rate of a detected flow rate value. 5 is a graph showing the relationship between the rotation speed of an internal combustion engine and the pulsation rate of a detected flow rate value. 5 is a graph showing the relationship between the rotation speed of an internal combustion engine and the pulsation rate of a detected flow rate value. FIG. 5 is a flow chart showing a first step of the control method for the internal combustion engine of FIG. 4 . FIG. 4 is a block diagram showing a second embodiment of a control device for an internal combustion engine according to the present disclosure.

Below, an embodiment of a control device and a control method for an internal combustion engine according to the present disclosure will be described with reference to the drawings.

[Embodiment 1]
1 is a schematic diagram of an engine system 200 which is an embodiment of an internal combustion engine control device according to the present disclosure. The engine system 200 includes, for example, an internal combustion engine 10, an intake passage 20, an exhaust passage 30, a turbocharger 40, an exhaust gas recirculation (EGR) passage 50, and an internal combustion engine control device 100. The internal combustion engine control device 100 of this embodiment is, for example, an electronic control unit (ECU) including a central processing unit (CPU) and a storage device (ROM, RAM, etc.).

The internal combustion engine 10 includes, for example, an intake valve 11, an exhaust valve 12, a fuel injection valve 13, a spark plug 14, a knock sensor 15, and a crank angle sensor 16. The internal combustion engine 10 is connected to an intake passage 20 and an exhaust passage 30. The intake valve 11 and the exhaust valve 12 each have a variable valve mechanism. The variable valve mechanism includes

sensors

11s, 12s that detect the opening and closing phases of the intake valve 11 and the exhaust valve 12, and is configured to continuously vary the phases of the intake valve 11 and the exhaust valve 12.

The fuel injection valve 13 is, for example, a direct injection valve that injects fuel directly into the cylinder of the internal combustion engine 10. The fuel injection valve 13 may also be a port injection type injection valve that injects fuel into an intake port. The spark plug 14 has an electrode portion exposed inside the cylinder of the internal combustion engine 10, and ignites the combustible mixture by a spark. The knock sensor 15 is provided in the cylinder block of the internal combustion engine 10 and detects the presence or absence of knock occurring in the combustion chamber. The crank angle sensor 16 is provided on the crankshaft of the internal combustion engine 10 and outputs a signal corresponding to the rotation angle of the crankshaft as a signal indicating the rotation speed of the crankshaft to the control device 100 of the internal combustion engine for each combustion cycle.

The intake flow path 20 has, for example, an upstream section 21, a midstream section 22, a downstream section 23, and a bypass section 24. The upstream section 21 is a flow path that connects an air cleaner (not shown) and a turbocharger 40. The midstream section 22 is a flow path that connects the turbocharger 40 and the downstream section 23 of the intake flow path 20. The downstream section 23 is an intake manifold connected to the internal combustion engine 10. The bypass section 24 is a flow path that connects the upstream section 21 and the midstream section 22.

In the upstream portion 21 of the intake flow path 20, for example, an airflow sensor 21s is provided that detects the flow rate of the intake air flowing through the intake flow path 20. In addition to the flow rate sensor, the airflow sensor 21s is equipped with a temperature sensor, a pressure sensor, and a humidity sensor, for example, and is configured as a physical quantity detection device that can detect the flow rate, temperature, pressure, and humidity of the intake air.

The airflow sensor 21s, for example, includes a thermal flow sensor and a bypass passage as a secondary passage that bypasses the air flowing through the intake passage 20 as the main passage. The thermal flow sensor is disposed in the bypass passage, and detects the temperature difference that occurs between the upstream and downstream sides of the heater due to the air flow using a bridge circuit including a resistance temperature sensor, thereby outputting a voltage signal corresponding to the flow rate of air flowing through the bypass passage.

In the midstream portion 22 of the intake passage 20, for example, an intercooler 22a, a supercharger temperature sensor 22b, and a throttle valve 22c are provided. The intercooler 22a cools the air whose temperature has increased due to adiabatic compression by the compressor 41 of the turbocharger 40, thereby lowering the temperature. The supercharger temperature sensor 22b is disposed downstream of the intercooler 22a, and measures the temperature of the air cooled by the intercooler 22a.

The throttle valve 22c is provided downstream of the supercharger temperature sensor 22b and narrows the intake passage 20 to control the amount of air flowing into the combustion chamber of the internal combustion engine 10. The throttle valve 22c is, for example, an electronically controlled butterfly valve whose valve opening can be controlled independently of the amount of depression of the accelerator pedal by the driver.

In the downstream portion 23 of the intake passage 20, for example, a boost pressure sensor 23a and a flow enhancement valve 23b are provided. The boost pressure sensor 23a is disposed downstream of the throttle valve 22c provided in the midstream portion 22. The flow enhancement valve 23b increases the turbulence in the flow inside the combustion chamber of the internal combustion engine 10 by causing a bias in the intake air.

The exhaust flow path 30 has, for example, an upstream section 31, a downstream section 32, and a bypass section 33. The upstream section 31 is an exhaust manifold that connects the internal combustion engine 10 and the turbocharger 40. The downstream section 32 is a flow path that connects the turbocharger 40 and a muffler (not shown). The bypass section 33 is a flow path that connects the upstream section 31 and the downstream section 32 of the exhaust flow path 30. The downstream section 32 of the exhaust flow path 30 is provided with, for example, an air-fuel ratio sensor 32a and an exhaust purification catalyst 32b.

The air-fuel ratio sensor 32a is provided downstream of the turbine 42 of the turbocharger 40, and outputs a signal indicating the detected oxygen concentration, i.e., the air-fuel ratio, to the internal combustion engine control device 60. The exhaust purification catalyst 32b is provided downstream of the air-fuel ratio sensor 32a, and purifies harmful exhaust gas components such as carbon monoxide, nitrogen compounds, and unburned hydrocarbons in the exhaust gas through catalytic reactions.

The turbocharger 40 is composed of a compressor 41 and a turbine 42, and is equipped with, for example, an air bypass valve 43 provided in the bypass section 24 of the intake passage 20, and a wastegate valve 44 provided in the bypass section 33 of the exhaust passage 30. The compressor 41 has compressor vanes, and the upstream section 21 of the intake passage 20 is connected to the upstream side of the compressor vanes, and the midstream section 22 of the intake passage 20 is connected to the downstream side of the compressor vanes.

The turbine 42 has turbine blades connected to the compressor blades, and the upstream portion 31 of the exhaust passage 30 is connected to the upstream side of the turbine blades, and the downstream portion 32 of the exhaust passage 30 is connected to the downstream side of the turbine blades. The turbine 42 converts the energy of the exhaust gas flowing through the exhaust passage 30 into rotational energy using the turbine blades. The compressor 41 compresses the air flowing through the intake passage 20 by rotating the compressor blades.

The air bypass valve 43, under the control of the internal combustion engine control device 100, prevents an excessive increase in pressure from downstream of the compressor 41 to the upstream of the throttle valve 22c. When the throttle valve 22c is suddenly closed in a supercharged state, the air bypass valve 43 is opened under the control of the internal combustion engine control device 100, causing the compressed intake air downstream of the compressor 41 to flow back through the bypass section 24 of the intake passage 20 to the upstream of the compressor 41. As a result, it becomes possible to reduce the supercharging pressure.

The wastegate valve 44 is an electrically operated valve whose opening can be freely controlled in relation to the boost pressure under the control of the internal combustion engine control device 100. The opening of the wastegate valve 44 is adjusted by the internal combustion engine control device 100 based on the boost pressure detected by the boost pressure sensor 23a provided in the downstream portion 23 of the intake passage 20. By allowing a portion of the exhaust gas to pass through the bypass portion 33 of the exhaust passage 30, the work that the exhaust gas imparts to the turbine 42 can be reduced, and as a result, the boost pressure can be maintained at the target pressure.

The EGR flow path 50 has one end connected to the downstream portion 32 of the exhaust flow path 30 and the other end connected to the upstream portion 21 of the intake flow path 20, and diverts exhaust gas from downstream of the exhaust purification catalyst 32b and returns it to the upstream of the compressor 41. The EGR flow path 50 is provided with, for example, an EGR cooler 51, an EGR valve 52, a temperature sensor 53, and a differential pressure sensor 54.

The EGR cooler 51 cools the exhaust gas. The EGR valve 52 is provided downstream of the EGR cooler 51 and controls the flow rate of the exhaust gas. The temperature sensor 53 detects the temperature of the exhaust gas upstream of the EGR valve 52. The differential pressure sensor 54 detects the differential pressure between the upstream and downstream sides of the EGR valve 52.

The internal combustion engine control device 100 controls each part of the engine system 200 and executes various data processing. The internal combustion engine control device 100 is connected to the various sensors and actuators mentioned above. The various actuators drive, for example, the throttle valve 22c, the fuel injection valve 13, the intake valve 11 and exhaust valve 12 with a variable valve mechanism, and the EGR valve 52.

The internal combustion engine control device 100 controls the operation of these various actuators. The internal combustion engine control device 100 also detects the operating state of the internal combustion engine 10 based on signals input from various sensors, and ignites the spark plug 14 at a timing determined according to the operating state.

FIG. 2 is a functional block diagram explaining some of the functions of the internal combustion engine control device 100 shown in FIG. 1. The internal combustion engine control device 100 of this embodiment has a restriction target value output unit 110, an operation control unit 120, a pulsation rate prediction unit 130, and an allowable pulsation rate output unit 140. Each of these units of the internal combustion engine control device 100 represents each function of the internal combustion engine control device 100 that is realized, for example, by the CPU executing a program stored in memory.

For example, when a driver of a vehicle equipped with an internal combustion engine control device 100 puts the shift lever into drive and depresses the accelerator pedal, the amount of accelerator pedal operation is detected by an accelerator position sensor and input to the internal combustion engine control device 100. Alternatively, information on the driving route from the current location to the destination is input to the internal combustion engine control device 100 installed in the vehicle, and automatic driving of the vehicle begins.

Then, the control device 100 of the internal combustion engine generates a control target value CTV of the internal combustion engine 10 according to, for example, the vehicle speed and target speed, the accelerator pedal operation amount, the flow rate detection value of the air flow sensor 21s, and the shift position. The generated control target value CTV is input, for example, to the restriction target value output unit 110, as shown in FIG. 2.

Although not particularly limited, the control target value CTV of the internal combustion engine 10 includes, for example, a target valve timing VT, a target gear ratio GR, and a target throttle opening TP. The target valve timing VT is, for example, a target value for the opening and closing timing of the intake valve 11 and exhaust valve 12 of the internal combustion engine 10. The target gear ratio GR is, for example, a target value for the gear ratio of the automatic transmission of the vehicle in which the internal combustion engine 10 is mounted. The target throttle opening TP is, for example, a target value for the opening of the throttle valve 22c that controls the amount of intake air flowing through the intake passage 20.

For example, when a predetermined condition is satisfied, the limit target value output unit 110 changes the input control target value CTV and outputs the limit target value CTVr. Furthermore, when the predetermined condition is not satisfied, the limit target value output unit 110 outputs the input control target value CTV as is to the operation control unit 120. The limit target value CTVr includes, for example, a limit valve timing VTr, a limit gear ratio GRr, and a limit throttle opening TPr. The predetermined conditions and the limit target value CTVr determined by the limit target value output unit 110 will be described in detail later.

The operation control unit 120 outputs control signals CS1, CS2, and CS3 for controlling the operating state of the internal combustion engine 10 based on the control target value CTV of the internal combustion engine 10 input from the restriction target value output unit 110. More specifically, the control signals CS1, CS2, and CS3 are, for example, control signals for actuators that open and close the intake valve 11 and exhaust valve 12, the automatic transmission, and the electronically controlled throttle valve 22c.

In other words, the operation control unit 120 controls the operating state of the internal combustion engine 10, for example, by controlling actuators that operate the intake valve 11, the exhaust valve 12, the automatic transmission, and the throttle valve 22c, based on the control target value CTV of the internal combustion engine 10. Here, the operating state of the internal combustion engine 10 includes, for example, the rotation speed of the internal combustion engine 10.

The pulsation rate prediction unit 130 outputs a predicted pulsation rate PRe that predicts the pulsation rate of the flow rate detection value of the airflow sensor 21s based on the control target value CTV of the internal combustion engine 10. Here, the pulsation rate is the ratio of the amplitude of the flow rate detection value to the average value of the flow rate detection value of the airflow sensor 21s. The pulsation rate is correlated with the rotation speed and intake air temperature of the internal combustion engine 10. For example, when the intake air temperature is at normal temperature of about 25°C and the rotation speed of the internal combustion engine 10 is a low rotation speed of about 800 to 1000 rpm, the pulsation rate is around 100%.

The pulsation rate increases as the rotation speed of the internal combustion engine 10 increases. For example, when the intake air temperature is at normal temperature of about 25°C, the pulsation rate peaks at over 400% when the rotation speed is about 1600 rpm, but gradually decreases as the rotation speed increases further. Furthermore, the peak of the pulsation rate shifts to the lower rotation side of the internal combustion engine 10 as the intake air temperature decreases, and shifts to the higher rotation side of the internal combustion engine 10 as the intake air temperature increases. Furthermore, the peak of the pulsation rate also tends to increase as the intake air temperature decreases.

The allowable pulsation rate output unit 140 outputs the allowable pulsation rate PRa, which is the maximum allowable pulsation rate based on the operating state of the internal combustion engine 10. More specifically, the allowable pulsation rate output unit 140 outputs the allowable pulsation rate PRa based on, for example, the rotation speed ES of the internal combustion engine 10.

FIG. 3 is a block diagram showing details of the pulsation rate prediction unit 130 and the allowable pulsation rate output unit 140 of the internal combustion engine control device 100 of FIG. 2. The pulsation rate prediction unit 130 has a pulsation rate map 131 that specifies the relationship between the control target value CTV of the internal combustion engine 10 under reference conditions in a predetermined temperature range and the pulsation rate of the flow detection value of the airflow sensor 21s. The pulsation rate map 131 includes, for example, a maximum pulsation rate map 131a and a pulsation rate ratio map 131b.

The maximum pulsation rate map 131a is a map that defines, for example, the relationship between the rotation speed ES of the internal combustion engine 10 and the maximum value of the pulsation rate of the flow rate detection value of the air flow sensor 21s. More specifically, the maximum pulsation rate map 131a defines, for example, the relationship between the rotation speed ES of the internal combustion engine 10 and the temperature of the intake air flowing through the intake passage 20, i.e., the intake air temperature IT, and the maximum value of the pulsation rate. The maximum pulsation rate map 131a is defined, for example, for each target valve timing VT.

When the target valve timing VT and the rotation speed ES of the internal combustion engine 10 are input, the maximum pulsation rate map 131a outputs the maximum pulsation rate that is the maximum value of the pulsation rate at that rotation speed ES. More specifically, when the intake air temperature IT, the target valve timing VT, and the rotation speed ES are input, the maximum pulsation rate map 131a outputs the maximum pulsation rate when those conditions are met.

The pulsation rate ratio map 131b is a map that defines the relationship between the rotation speed ES and target throttle opening TP of the internal combustion engine 10 and the ratio to the maximum value of the pulsation rate, i.e., the pulsation rate ratio. The pulsation rate ratio map 131b is defined for each target valve timing VT, for example, in the same way as the maximum pulsation rate map 131a. When the rotation speed ES and target throttle opening TP are input, the pulsation rate ratio map 131b outputs the pulsation rate ratio when the conditions are met.

The pulsation rate map 131 estimates the pulsation rate at the input rotation speed ES, for example, by multiplying the maximum pulsation rate output from the maximum pulsation rate map 131a by the pulsation rate ratio output from the pulsation rate ratio map 131b. That is, the pulsation rate map 131 outputs a predicted pulsation rate PRe, which is an estimate of the pulsation rate of the flow rate detection value by the airflow sensor 21s, based on, for example, the intake air temperature IT, the target valve timing VT, and the rotation speed ES of the internal combustion engine 10.

As described above, the pulsation rate prediction unit 130 outputs the predicted pulsation rate PRe based on the rotation speed ES and intake air temperature IT of the internal combustion engine 10 in addition to the control target value CTV including the target throttle opening TP. Here, the target throttle opening TP is the opening of the throttle valve 22c that controls the intake air amount. The pulsation rate prediction unit 130 also outputs the predicted pulsation rate PRe based on the control target value CTV including the target valve timing VT. Here, the target valve timing VT is the opening and closing timing of the intake valve 11 and the exhaust valve 12 of the internal combustion engine 10. The pulsation rate prediction unit 130 may also output the predicted pulsation rate PRe based on the control target value CTV including the target boost pressure of the turbocharger 40 provided in the exhaust flow path 30 and the intake flow path 20 of the internal combustion engine 10.

The allowable pulsation rate output unit 140 is provided with, for example, an allowable pulsation rate map 141 that indicates the relationship between the operating state of the internal combustion engine 10 and the allowable pulsation rate PRa, which is the maximum value of the allowable pulsation rate. More specifically, the allowable pulsation rate output unit 140 is provided with, for example, an allowable pulsation rate map 141 that indicates the relationship between the rotation speed ES of the internal combustion engine 10 and the allowable pulsation rate PRa. The allowable pulsation rate map 141 is defined, for example, for each target valve timing VT. The allowable pulsation rate map 141 outputs the allowable pulsation rate PRa when the target valve timing VT and the rotation speed ES, which is the operating state of the internal combustion engine 10, are input, for example.

Below, with reference to FIG. 4, a method for controlling an internal combustion engine using the internal combustion engine control device 100 of this embodiment will be described. FIG. 4 is a flow diagram showing an internal combustion engine control method ECM using the internal combustion engine control device 100 of FIG. 2 and FIG. 3. When the internal combustion engine control device 100 starts the internal combustion engine control method ECM shown in FIG. 4, it first executes a pulsation rate prediction process S1 that outputs a predicted pulsation rate PRe based on the control target value CTV of the internal combustion engine 10.

In this step S1, the restriction target value output unit 110 outputs the input control target value CTV as is to the operation control unit 120, for example, as shown in FIG. 2. The pulsation rate prediction unit 130 outputs a predicted pulsation rate PRe, which is a pulsation rate predicted based on the control target value CTV input from the restriction target value output unit 110, using, for example, a pulsation rate map 131 shown in FIG. 3.

More specifically, as shown in FIG. 3, for example, the target valve timing VT and the target throttle opening TP, the intake air temperature IT detected by the airflow sensor 21s, and the rotation speed ES of the internal combustion engine 10 based on the detection result of the crank angle sensor 16 are input to the pulsation rate map 131. As a result, the pulsation rate map 131 outputs a predicted pulsation rate PRe, which is a prediction result of the pulsation rate of the flow rate detection value by the airflow sensor 21s when these conditions are satisfied.

Next, the internal combustion engine control device 100 executes an allowable pulsation rate output step S2 for outputting the allowable pulsation rate PRa, as shown in FIG. 4. In this step S2, the allowable pulsation rate output unit 140 uses, for example, an allowable pulsation rate map 141 shown in FIG. 3, and outputs the allowable pulsation rate PRa based on the operating state of the internal combustion engine 10. More specifically, as shown in FIG. 3, for example, the rotation speed ES and the target valve timing VT of the internal combustion engine 10 are input to the allowable pulsation rate map 141.

As a result, the allowable pulsation rate map 141 outputs the allowable pulsation rate PRa, which is the maximum allowable value of the pulsation rate of the flow rate detection value by the airflow sensor 21s when these conditions are met. In steps S1 and S2, the predicted pulsation rate PRe and the allowable pulsation rate PRa output from the pulsation rate prediction unit 130 and the allowable pulsation rate output unit 140, respectively, are input to the restriction target value output unit 110, for example, as shown in FIG. 2.

Next, the internal combustion engine control device 100 executes a comparison step S3 in which the predicted pulsation rate PRe is compared with the allowable pulsation rate PRa, as shown in FIG. 4. In this step S3, the restriction target value output unit 110 compares, for example, the predicted pulsation rate PRe and the allowable pulsation rate PRa input in steps S1 and S2. In this step S3, if the restriction target value output unit 110 determines that the predicted pulsation rate PRe is equal to or lower than the allowable pulsation rate PRa (YES), it outputs the control target value CTV input to the restriction target value output unit 110 as is to the operation control unit 120.

Figures 5 to 7 are graphs showing the relationship between the rotation speed ES of the internal combustion engine 10 and the pulsation rate of the flow rate detection value by the air flow sensor 21s. In Figures 5 to 7, the solid curve C1 shows the relationship between the rotation speed ES and the pulsation rate when the target throttle opening TP is fully open and the intake air temperature IT is 25°C. The flow rate detection value by the air flow sensor 21s is affected by the pulsation of the intake air flowing through the intake passage 20, for example, and an error occurs.

The pulsation correction value for correcting the error in the flow rate detection value of the air flow sensor 21s due to the pulsation of the intake air is determined, for example, by the following procedure. The internal combustion engine 10 is operated under reference conditions in a predetermined temperature range where the intake air temperature IT is 25°C, for example, while changing the rotation speed ES. The flow rate of the intake air flowing through the intake passage 20 is then detected by the air flow sensor 21s, and is also detected by a known method in which the effect of the intake air pulsation on the flow rate detection value is smaller than that of the air flow sensor 21s.

As a result, the relationship between the rotation speed ES of the internal combustion engine 10, the pulsation rate of the flow rate detection value by the airflow sensor 21s, and the error in the flow rate detection value by the airflow sensor 21s is obtained, and a pulsation correction value is determined so as to correct the error in the flow rate detection value. That is, as shown by the solid lines in Figures 5 to 7, the area on and below curve C1, which shows the relationship between the rotation speed ES and the pulsation rate when the target throttle opening TP is fully open and the intake air temperature IT is 25°C, is the area in which the pulsation correction value is determined and the flow rate detection value by the airflow sensor 21s is adapted.

The points on this solid curve C1 represent the allowable pulsation rate PRa for each rotation speed ES. Therefore, if the comparison step S3 in Figure 4 determines that the predicted pulsation rate PRe is equal to or lower than the allowable pulsation rate PRa (YES), the predicted pulsation rate PRe is in the region on or below the solid curve C1. As described above, this region is the region in which the pulsation correction value is determined and the flow rate detection value by the airflow sensor 21s is adapted, and this is the region in which the flow rate of air flowing through the intake flow path 20 can be accurately detected by the airflow sensor 21s.

Therefore, if the determination result in step S3 is positive, in operation control step S4 in FIG. 4, the restriction target value output unit 110 shown in FIG. 2 outputs the input control target value CTV of the internal combustion engine 10 to the operation control unit 120 without changing it. Then, the operation control unit 120 outputs control signals CS1, CS2, CS3 based on the control target value CTV of the internal combustion engine 10 to, for example, the actuators that open and close the intake valve 11 and exhaust valve 12, the automatic transmission, and the electronically controlled throttle valve 22c.

As a result, the operating state of the internal combustion engine 10 is controlled based on the control target value CTV. Furthermore, the internal combustion engine control device 100 calculates a new control target value CTV for the internal combustion engine 10, for example, using an adapted flow rate detection value of the air flow sensor 21s that detects the intake air amount of the internal combustion engine 10. Thereafter, the internal combustion engine control device 100 ends the internal combustion engine control method ECM shown in FIG. 4, and repeats it, for example, at a predetermined period.

On the other hand, when the intake air temperature IT drops drastically, for example in an extremely low temperature environment, the resonant frequency of the intake air drops. As a result, the relationship between the rotation speed of the internal combustion engine 10 and the pulsation rate of the flow detection value of the air flow sensor 21s when the intake air temperature IT is 25°C and the target throttle opening TP is fully open, as shown by the solid curve C1 in Figure 5, shifts to the lower rotation speed side.

For example, the relationship between the rotation speed of the internal combustion engine 10 and the pulsation rate of the flow detection value of the air flow sensor 21s when the intake air temperature IT is -40°C and the target throttle opening TP is fully open is shown by the dashed curve C2 in Figure 5. Among the points on this dashed curve C2 and the area below it, the area above the solid curve C1 exceeds the allowable pulsation rate PRa.

In other words, the region R1 between the dashed curve C2 and the solid curve C1 is a region in which the pulsation correction value for the flow rate detection value of the airflow sensor 21s is not specified, and errors in the flow rate detection value cannot be corrected. For example, assume that the intake air temperature IT is a low temperature of -40°C, and in step S3 shown in Figure 4, the restriction target value output unit 110 determines that the predicted pulsation rate PRe exceeds the allowable pulsation rate PRa (NO).

Then, as shown in FIG. 2, the restriction target value output unit 110 outputs a restriction target value CTVr obtained by changing the control target value CTV so as to reduce the pulsation rate. More specifically, the restriction target value output unit 110 executes step S5 of changing the target throttle opening TP, for example, as shown in FIG. 4. In this step S5, the restriction target value output unit 110 outputs a restriction throttle opening TPr obtained by reducing the target throttle opening TP, instead of the target throttle opening TP shown in FIG. 2.

Next, the restriction target value output unit 110 executes step S6 of changing the target gear ratio GR, for example, as shown in FIG. 4. In this step S6, instead of the target gear ratio GR shown in FIG. 2, the restriction target value output unit 110 outputs the restriction gear ratio GRr, which is obtained by increasing or decreasing the target gear ratio GR so as to reduce the predicted pulsation rate PRe.

More specifically, when the intake air temperature IT drops and the solid curve C1 in FIG. 5 shifts to the lower rotation speed side as shown by the dashed curve C2, the limiting gear ratio GRr is output to downshift and increase the rotation speed ES of the internal combustion engine 10. Conversely, when the intake air temperature IT rises and the solid curve C1 in FIG. 5 shifts to the higher rotation speed side as shown by the dashed curve C3, the limiting gear ratio GRr is output to upshift and decrease the rotation speed ES of the internal combustion engine 10.

Next, the restriction target value output unit 110 executes step S7 of changing the target valve timing VT, for example, as shown in FIG. 4. In this step S7, instead of the target valve timing VT shown in FIG. 2, the restriction target value output unit 110 outputs the restriction valve timing VTr that reduces the amount of air spit back from the combustion chamber to the intake passage 20 during the compression stroke of the internal combustion engine 10 compared to the target valve timing VT.

Then, in step S1 shown in FIG. 4, the limit valve timing VTr and limit throttle opening TPr, which are the limit target value CTVr, are input to the pulsation rate prediction unit 130 as shown in FIG. 2 and FIG. 3. In this case, the pulsation rate prediction unit 130 outputs the predicted pulsation rate PRe based on the limit valve timing VTr and limit throttle opening TPr, which are the limit target value CTVr.

In the next step S2, the allowable pulsation rate output unit 140, as shown in Figures 2 and 3, takes the restricted valve timing VTr, which is the restricted target value CTVr, as input instead of the target valve timing VT, which is the control target value CTV, and outputs the allowable pulsation rate PRa.

The predicted pulsation rate PRe based on the limit throttle opening TPr moves, for example, as shown by arrow A1 in FIG. 5, from region R1 above the solid curve C1 to a region above or below the dashed curve C2', which has a peak below the solid curve C1. Also, due to a change in the rotation speed ES of the internal combustion engine 10 based on the limit gear ratio GRr, the predicted pulsation rate PRe moves, for example, as shown by arrow A2 in FIG. 6, from region R1 above the solid curve C1 to a region below the solid curve C1.

Also, as shown in FIG. 7, the dashed curve C2 based on the target valve timing VT moves, for example, as indicated by arrow A3, to the region above or below dashed curve C2' based on the limit valve timing VTr below curve C2. However, if part of the region below curve C2' is above solid curve C1, the limit throttle opening TPr may also be used instead of target throttle opening TP. As a result, the predicted pulsation rate PRe moves, for example, as indicated by arrow A3, from region R2 above solid curve C1 to the region above or below dashed curve C2'', which has a peak below solid curve C1.

As shown in Figures 5 to 7, when the predicted pulsation rate PRe moves onto the solid curve C1 or into the area below the curve C1, the restriction target value output unit 110 determines in step S3 shown in Figure 4 that the predicted pulsation rate PRe is equal to or lower than the allowable pulsation rate PRa (YES). Then, the operation control unit 120 executes an operation control step S4 in which the operation state of the internal combustion engine 10 is controlled. In this step S4, when the restriction target value CTVr is input, the operation control unit 120 controls the operation state of the internal combustion engine 10 based on the input restriction target value CTVr.

On the other hand, if the restriction target value output unit 110 determines in step S3 shown in FIG. 4 that the predicted pulsation rate PRe exceeds the allowable pulsation rate PRa (NO), steps S5 to S7 are executed again to output the restriction target value CTVr by the restriction target value output unit 110. By repeating this process, in step S3, the restriction target value output unit 110 determines that the predicted pulsation rate PRe is equal to or lower than the allowable pulsation rate PRa (YES), and the restriction target value output unit 110 executes step S4 to control the operating state of the internal combustion engine 10.

As a result, as described above, the pulsation correction value is determined, and the internal combustion engine 10 is operated in the region below the solid curve C1 shown in Figure 5, to which the flow rate detection value by the airflow sensor 21s is adapted. Therefore, the airflow sensor 21s can accurately detect the flow rate of air flowing through the intake passage 20. As a result, the internal combustion engine control device 100, which controls the internal combustion engine 10 using the flow rate detection value by the airflow sensor 21s, can prevent deterioration of the operability and exhaust components of the internal combustion engine 10.

FIG. 8 is a flow diagram showing the pre-process PP of the control method ECM for an internal combustion engine shown in FIG. 4. The pre-process PP of the control method ECM for an internal combustion engine includes, for example, a pulsation rate learning process PP1 and an allowable pulsation rate calibration process PP2. The pulsation rate learning process PP1 is a process for learning the relationship between the control target value CTV and the pulsation rate of the flow detection value of the airflow sensor 21s under the reference conditions of the internal combustion engine 10 described above by machine learning, and generating, for example, a pulsation rate map 131 including a maximum pulsation rate map 131a and a pulsation rate ratio map 131b.

The allowable pulsation rate calibration process PP2 is a process for generating the allowable pulsation rate map 141 based on the pulsation rate map 131. More specifically, for example, the maximum pulsation rate when the throttle opening is fully open for each rotation speed of the internal combustion engine 10 is derived from the maximum pulsation rate map 131a, and the maximum pulsation rate for each rotation speed of the internal combustion engine 10 is set as the allowable pulsation rate PRa.

The operation of the internal combustion engine control device 100 and the internal combustion engine control method ECM of this embodiment will be described below.

The internal combustion engine control device 100 of this embodiment controls the internal combustion engine 10 using the flow rate detection value of the air flow sensor 21s that detects the intake air volume of the internal combustion engine 10. The internal combustion engine control device 100 includes an operation control unit 120, a pulsation rate prediction unit 130, an allowable pulsation rate output unit 140, and a restriction target value output unit 110. The operation control unit 120 controls the operating state of the internal combustion engine 10 based on a control target value CTV of the internal combustion engine 10. The pulsation rate prediction unit 130 outputs a predicted pulsation rate PRe that predicts the pulsation rate of the flow rate detection value by the air flow sensor 21s based on the control target value CTV. The allowable pulsation rate output unit 140 outputs an allowable pulsation rate PRa that is the maximum value of the allowable pulsation rate based on the operating state of the internal combustion engine 10. When the predicted pulsation rate PRe exceeds the allowable pulsation rate PRa, the restriction target value output unit 110 outputs a restriction target value CTVr obtained by changing the control target value CTV so as to reduce the pulsation rate. In addition, when the restriction target value CTVr is input, the operation control unit 120 controls the operating state of the internal combustion engine 10 based on the restriction target value CTVr.

With this configuration, the internal combustion engine control device 100 of this embodiment obtains the predicted pulsation rate PRe and the allowable pulsation rate PRa based on the control target value CTV of the internal combustion engine 10. Then, when the predicted pulsation rate PRe exceeds the allowable pulsation rate PRa and enters the region R1, R3 above the solid curve C1 shown in Figures 5 to 7, the restriction target value output unit 110 outputs the restriction target value CTVr. As a result, the operation control unit 120 controls the operating state of the internal combustion engine 10 based on the restriction target value CTVr obtained by changing the control target value CTV so as to reduce the pulsation rate. As a result, as shown by the arrows A1 and A2 in Figures 5 and 6, the relationship between the pulsation rate of the flow rate detection value of the airflow sensor 21s and the rotation speed of the internal combustion engine 10 moves to the region on or below the solid curve C1. The region on or below this solid curve C1 is the region in which the pulsation correction value is determined and the flow rate detection value by the airflow sensor 21s is adapted. Therefore, the internal combustion engine 10 can be prevented from operating in the regions R1 and R3 where the pulsation error cannot be corrected, and the internal combustion engine 10 can be controlled using the flow rate detection value of the air flow sensor 21s in which the pulsation error has been corrected. Therefore, the internal combustion engine control device 100 of this embodiment can prevent deterioration of the operating performance and exhaust components of the internal combustion engine 10.

In addition, in the internal combustion engine control device 100 of this embodiment, the control target value CTV includes a target throttle opening TP, which is a target value for the opening of the throttle valve 22c that controls the intake air amount. In addition, the limit target value CTVr includes a limit throttle opening TPr that is a reduction of the target throttle opening TP.

With this configuration, as shown in FIG. 5, for example, when the intake air temperature IT is extremely low, such as -40°C, the dashed curve C2 showing the relationship between the pulsation rate of the flow detection value of the air flow sensor 21s and the rotation speed of the internal combustion engine 10 when the target throttle opening TP is fully open can be moved to the dashed curve C2' below the solid curve C1. This makes it possible to avoid operating the internal combustion engine 10 in the region R1 where the pulsation error cannot be corrected, as described above, and to control the internal combustion engine 10 using the flow detection value of the air flow sensor 21s with the pulsation error corrected.

Furthermore, in the internal combustion engine control device 100 of this embodiment, the control target value CTV includes a target valve timing VT, which is a target value for the opening and closing timing of the intake valve 11 and exhaust valve 12 of the internal combustion engine 10. Furthermore, the restriction target value CTVr includes a restriction valve timing VTr that reduces the amount of air spit back from the combustion chamber to the intake passage 20 during the compression stroke of the internal combustion engine 10 to less than the control target value CTV.

As shown in FIG. 7, this configuration allows the dashed curve C2, which indicates the relationship between the pulsation rate of the flow detection value of the air flow sensor 21s and the rotation speed of the internal combustion engine 10 when the target throttle opening TP is fully open at an extremely low intake temperature IT of -40°C, to be shifted downward to the dashed curve C2'. Furthermore, by including the limit throttle opening TPr in the restriction target value CTVr, the dashed curve C2' can be shifted downward to the dashed curve C2" below the solid curve C1. In this case, the difference between the target throttle opening TP and the limit throttle opening TPr can be reduced compared to when the restriction target value CTVr includes only the limit throttle opening TPr.

In addition, in the internal combustion engine control device 100 of this embodiment, the control target value CTV includes a target gear ratio GR of the automatic transmission of the vehicle in which the internal combustion engine 10 is mounted. The limit target value CTVr includes a limit gear ratio GRr that is obtained by increasing or decreasing the target gear ratio GR so as to reduce the predicted pulsation rate PRe.

With this configuration, as shown in FIG. 6, for example, the rotation speed of the internal combustion engine 10 can be increased when the intake air temperature IT is extremely low, such as -40°C. As a result, the point in region R1 above the solid curve C1 can be moved below the solid curve C1, as shown by arrow A2. This makes it possible to avoid operating the internal combustion engine 10 in region R1 where the pulsation error cannot be corrected, as described above, and to control the internal combustion engine 10 using the flow rate detection value of the air flow sensor 21s in which the pulsation error has been corrected.

Furthermore, in the internal combustion engine control device 100 of this embodiment, the pulsation rate prediction unit 130 outputs the predicted pulsation rate PRe based on the rotation speed ES and intake temperature IT of the internal combustion engine 10 in addition to the control target value CTV, which includes the opening degree of the throttle valve 22c that controls the intake air amount. This configuration enables the pulsation rate prediction unit 130 to output a more accurate predicted pulsation rate PRe that is closer to the actual pulsation rate.

Furthermore, in the internal combustion engine control device 100 of this embodiment, the pulsation rate prediction unit 130 outputs the predicted pulsation rate PRe based on a control target value CTV that includes the opening and closing timing of the intake valve 11 and the exhaust valve 12 of the internal combustion engine 10. With this configuration, the pulsation rate prediction unit 130 is able to output a more accurate predicted pulsation rate PRe that is closer to the actual pulsation rate.

Furthermore, in the internal combustion engine control device 100 of this embodiment, the pulsation rate prediction unit 130 can output the predicted pulsation rate PRe based on a control target value CTV including a target boost pressure of the turbocharger 40 provided in the intake passage 20 and exhaust passage 30 of the internal combustion engine 10. With this configuration, the pulsation rate prediction unit 130 can output a more accurate predicted pulsation rate PRe that is closer to the actual pulsation rate.

In addition, in the internal combustion engine control device 100 of this embodiment, when the restriction target value CTVr is input, the pulsation rate prediction unit 130 outputs the predicted pulsation rate PRe based on the restriction target value CTVr. With this configuration, the predicted pulsation rate PRe can be set to be equal to or less than the allowable pulsation rate PRa by repeating steps S1 to S7 shown in FIG. 4.

The internal combustion engine control method ECM of this embodiment is a method for controlling the internal combustion engine 10 using a flow rate detection value of the air flow sensor 21s that detects the amount of intake air of the internal combustion engine 10. The internal combustion engine control method ECM has an operation control step S4, a pulsation rate prediction step S1, an allowable pulsation rate output step S2, and a restriction target value output step S5-S7. The operation control step S4 is a step for controlling the operating state of the internal combustion engine 10 based on a control target value CTV of the internal combustion engine 10. The allowable pulsation rate output step S2 is a step for outputting a predicted pulsation rate PRe that predicts the pulsation rate based on the control target value CTV using a pulsation rate map 131 that specifies the relationship between the control target value CTV of the internal combustion engine 10 and the pulsation rate of the flow rate detection value of the air flow sensor 21s under reference conditions in a predetermined temperature range. The allowable pulsation rate output step S2 is a step of outputting the allowable pulsation rate PRa based on the operating state of the internal combustion engine 10 using an allowable pulsation rate map 141 that shows the relationship between the operating state of the internal combustion engine 10 and the allowable pulsation rate PRa, which is the maximum allowable pulsation rate. The restriction target value output steps S5-S7 are steps of outputting a restriction target value CTVr that changes the control target value CTV so as to reduce the pulsation rate when the predicted pulsation rate PRe exceeds the allowable pulsation rate PRa. The internal combustion engine control method ECM of this embodiment controls the operating state of the internal combustion engine 10 based on the restriction target value CTVr when the restriction target value CTVr is input in the operation control step S4.

With this configuration, according to the internal combustion engine control method ECM of this embodiment, the predicted pulsation rate PRe and the allowable pulsation rate PRa are obtained based on the control target value CTV of the internal combustion engine 10. Then, when the predicted pulsation rate PRe exceeds the allowable pulsation rate PRa and enters the region R1, R3 above the solid curve C1 shown in Figures 5 to 7, the restriction target value CTVr can be output. As a result, the operating state of the internal combustion engine 10 is controlled based on the restriction target value CTVr in which the control target value CTV is changed so as to reduce the pulsation rate. As a result, as shown by the arrows A1 and A2 in Figures 5 and 6, the relationship between the pulsation rate of the flow rate detection value of the airflow sensor 21s and the rotation speed of the internal combustion engine 10 moves to the region on or below the solid curve C1. The region on or below this solid curve C1 is the region in which the pulsation correction value is determined and the flow rate detection value by the airflow sensor 21s is adapted. Therefore, it is possible to avoid operating the internal combustion engine 10 in the regions R1 and R3 where the pulsation error cannot be corrected, and to control the internal combustion engine 10 using the flow rate detection value of the air flow sensor 21s in which the pulsation error has been corrected. Therefore, according to the internal combustion engine control method ECM of this embodiment, it is possible to prevent deterioration of the operating performance and exhaust components of the internal combustion engine 10.

Furthermore, as shown in FIG. 8, the internal combustion engine control method ECM of this embodiment includes a pulsation rate learning process PP1 and an allowable pulsation rate calibration process PP2 as pre-processes PP. The pulsation rate learning process PP1 is a process for learning the relationship between the control target value CTV and the pulsation rate under the reference conditions of the internal combustion engine 10 to generate a pulsation rate map 131. The allowable pulsation rate calibration process PP2 is a process for generating an allowable pulsation rate map 141 based on the pulsation rate map 131.

With this configuration, the internal combustion engine control method ECM of this embodiment can generate the pulsation rate map 131 and the allowable pulsation rate map 141 used in the above-mentioned pulsation rate prediction process S1 and allowable pulsation rate output process S2 by machine learning.

As described above, this embodiment can provide an internal combustion engine control device 100 and an internal combustion engine control method ECM that can prevent the relationship between the rotation speed of the internal combustion engine 10 and the pulsation rate of the intake air from going outside the range for which the pulsation correction value is determined, thereby preventing deterioration of the operating performance and exhaust components of the internal combustion engine 10.

[Embodiment 2]
Hereinafter, a second embodiment of the control device for an internal combustion engine according to the present disclosure will be described with reference to Fig. 9 in addition to Fig. 1 and Fig. 3 to Fig. 8 of the first embodiment described above. Fig. 9 is a block diagram showing an embodiment of the control device for an internal combustion engine according to the present disclosure, and corresponds to Fig. 2 of the first embodiment.

The internal combustion engine control device 100A of this embodiment differs from the internal combustion engine control device 100 of the above-described first embodiment in that it further includes a back calculation unit 150. The other configuration of the internal combustion engine control device 100A of this embodiment is similar to that of the internal combustion engine control device 100 of the above-described first embodiment, so similar parts are given the same reference numerals and descriptions thereof are omitted.

The inverse calculation unit 150 shown in FIG. 9 outputs an allowable target value, which is an allowable value of the control target value CTV of the internal combustion engine 10, based on the allowable pulsation rate PRa in the reverse procedure to that of the pulsation rate prediction unit 130. More specifically, the inverse calculation unit 150 shown in FIG. 9 receives, for example, the maximum pulsation rate PRg output from the maximum pulsation rate map 131a of the pulsation rate prediction unit 130 shown in FIG. 3, the rotation speed ES of the internal combustion engine 10, and the allowable pulsation rate PRa output from the allowable pulsation rate output unit 140.

The reverse calculation unit 150 is provided with, for example, a throttle opening reverse lookup map (not shown). The throttle opening reverse lookup map takes as input, for example, an allowable pulsation rate ratio obtained by dividing the predicted pulsation rate PRe by the maximum pulsation rate PRg, and outputs a limited throttle opening TPr based on the allowable pulsation rate ratio and the rotation speed ES.

In other words, the reverse calculation unit 150 outputs the limit throttle opening TPr as an allowable target value that is an allowable value of the control target value CTV of the internal combustion engine 10 based on the maximum pulsation rate PRg according to the operating state of the internal combustion engine 10, in the reverse procedure of the pulsation rate prediction unit 130. The limit throttle opening TPr output from the reverse calculation unit 150 is input to the limit target value output unit 110. The limit target value output unit 110 outputs the limit throttle opening TPr as the allowable target value input from the reverse calculation unit 150 as the limit target value CTVr.

As described above, the internal combustion engine control device 100A of this embodiment further includes a reverse calculation unit 150 in addition to the components of the internal combustion engine control device 100 of the first embodiment described above. The reverse calculation unit 150 outputs the limit throttle opening TPr as an allowable target value that is an allowable value of the control target value CTV of the internal combustion engine 10, in the reverse procedure of the pulsation rate prediction unit 130, based on the maximum pulsation rate PRg according to the operating state of the internal combustion engine 10. In addition, the limit target value output unit 110 outputs the limit throttle opening TPr as an allowable target value input from the reverse calculation unit 150 as the limit target value CTVr.

With this configuration, the internal combustion engine control device 100A of this embodiment can output the limit throttle opening angle TPr using the reverse calculation unit 150 without repeatedly executing steps S1 to S7 shown in FIG. 4, as in the internal combustion engine control device 100 of the above-mentioned first embodiment. This makes it possible to reduce the calculation load of the internal combustion engine control device 100A.

　Although the embodiments of the control device and control method for an internal combustion engine according to the present disclosure have been described above, the control device and control method for an internal combustion engine according to the present disclosure are not limited to the above-described embodiments. Addition, omission, substitution, and other modifications of the configuration are possible within the scope of the spirit of the present disclosure.

10 Internal combustion engine 11 Intake valve 12 Exhaust valve 20 Intake flow path 21s Air flow sensor 22c Throttle valve 30 Exhaust flow path 40 Turbocharger 100 Internal combustion engine control device 100A Internal combustion engine control device 110 Restriction target value output unit 120 Operation control unit 130 Pulsation rate prediction unit 131 Pulsation rate map 140 Allowable pulsation rate output unit 141 Allowable pulsation rate map 150 Back calculation unit CTV Control target value CTVr Restriction target value ECM Internal combustion engine control method ES Revolution speed (operation state)
GR target gear ratio GRr limit gear ratio IT intake air temperature PP1 pulsation rate learning process PP2 allowable pulsation rate calibration process PRa allowable pulsation rate PRe predicted pulsation rate PRg maximum pulsation rate S1 pulsation rate prediction process S2 allowable pulsation rate output process S4 operation control process S5 limit target value output process S6 limit target value output process S7 limit target value output process TP target throttle opening TPr limit throttle opening (allowable target value)
VT Target valve timing VTr Limit valve timing

Claims

A control device for an internal combustion engine that controls an internal combustion engine using a flow rate detection value of an air flow sensor that detects an intake air amount of the internal combustion engine,
an operation control unit that controls an operation state of the internal combustion engine based on a control target value of the internal combustion engine;
a pulsation rate prediction unit that predicts the pulsation rate of the flow rate detection value based on the control target value and outputs a predicted pulsation rate;
an allowable pulsation rate output unit that outputs an allowable pulsation rate that is a maximum value of the pulsation rate that is allowable based on the operating state of the internal combustion engine;
a restriction target value output unit that outputs a restriction target value obtained by changing the control target value so as to reduce the pulsation rate when the predicted pulsation rate exceeds the allowable pulsation rate,
The control device for an internal combustion engine, wherein the operation control unit controls the operation state of the internal combustion engine based on the restriction target value when the restriction target value is input.
the control target value includes a target throttle opening, which is a target value of an opening of a throttle valve that controls the intake air amount,
2. The control device for an internal combustion engine according to claim 1, wherein the restriction target value includes a throttle opening limit obtained by reducing the target throttle opening.
the control target value includes a target valve timing that is a target value of an opening/closing timing of an intake valve and an exhaust valve of the internal combustion engine,
2. The control device for an internal combustion engine according to claim 1, wherein the restriction target value includes a restriction valve timing that reduces the amount of spit-back from a combustion chamber to an intake passage during a compression stroke of the internal combustion engine to a value less than the target valve timing.
the control target value includes a target gear ratio of an automatic transmission of a vehicle equipped with the internal combustion engine,
2. The control device for an internal combustion engine according to claim 1, wherein the limit target value includes a limit speed ratio obtained by increasing or decreasing the target speed ratio so as to reduce the predicted pulsation rate.
The control device for an internal combustion engine according to claim 1, characterized in that the pulsation rate prediction unit outputs the predicted pulsation rate based on the rotation speed and intake air temperature of the internal combustion engine in addition to the control target value including the opening degree of a throttle valve that controls the intake air amount.
The control device for an internal combustion engine according to claim 5, characterized in that the pulsation rate prediction unit outputs the predicted pulsation rate based on the control target value including the opening and closing timing of the intake valve and exhaust valve of the internal combustion engine.
The control device for an internal combustion engine according to claim 5, characterized in that the pulsation rate prediction unit outputs the predicted pulsation rate based on the control target value including a target boost pressure of a turbocharger provided in the exhaust flow path and the intake flow path of the internal combustion engine.
The control device for an internal combustion engine according to claim 1, characterized in that the pulsation rate prediction unit outputs the predicted pulsation rate based on the restriction target value when the restriction target value is input.
a reverse calculation unit that outputs an allowable target value, which is an allowable value of the control target value of the internal combustion engine, in a reverse procedure to that of the pulsation rate prediction unit, based on a maximum pulsation rate corresponding to the operating state of the internal combustion engine;
2. The control device for an internal combustion engine according to claim 1, wherein the restriction target value output unit outputs the permissible target value as the restriction target value.
A method for controlling an internal combustion engine using a flow rate detection value of an air flow sensor that detects an intake air amount of the internal combustion engine, comprising:
an operation control step of controlling an operation state of the internal combustion engine based on a control target value of the internal combustion engine;
a pulsation rate prediction step of predicting the pulsation rate based on the control target value of the internal combustion engine by using a pulsation rate map that defines a relationship between the control target value of the internal combustion engine and the pulsation rate of the flow rate detection value under a reference condition in a predetermined temperature range, and outputting a predicted pulsation rate obtained by predicting the pulsation rate based on the control target value;
an allowable pulsation rate output step of outputting the allowable pulsation rate based on the operating state of the internal combustion engine using an allowable pulsation rate map indicating a relationship between the operating state of the internal combustion engine and an allowable pulsation rate that is a maximum allowable value of the pulsation rate;
and a restriction target value output step of outputting a restriction target value obtained by changing the control target value so as to reduce the pulsation rate when the predicted pulsation rate exceeds the allowable pulsation rate,
A method for controlling an internal combustion engine, comprising the steps of: when the restriction target value is input, controlling the operating state of the internal combustion engine based on the restriction target value in the operation control step.
a pulsation rate learning step of learning a relationship between the control target value and the pulsation rate under the reference condition to generate the pulsation rate map;
11. The method according to claim 10, further comprising: a step of calibrating an allowable pulsation rate to generate the allowable pulsation rate map based on the pulsation rate map.