阅读说明：本技术 发动机控制装置及发动机控制方法以及存储介质 (Engine control device, engine control method, and storage medium ) 是由 山田贵文 阿南贵宏 栗田俊介 于 2020-08-14 设计创作，主要内容包括：提供发动机控制装置、发动机控制方法及存储介质。第二运算处理以不使用空气流量计的检测结果的方式运算进气量。判定处理在确认了进气脉动的周期中的进气流量的平均值即平均流量与该周期中的进气流量的最小值即最小流量之差处于大的状态的情况下,判定为进气脉动处于大的状态。运算方式切换处理在判定为进气脉动处于大的状态时,选择通过第二运算处理而得到的进气量的运算值。(An engine control device, an engine control method, and a storage medium are provided. The second arithmetic processing calculates the intake air amount without using the detection result of the air flow meter. The determination process determines that the intake pulsation is in a large state when it is confirmed that the difference between the average flow rate, which is the average value of the intake flow rate in a cycle of the intake pulsation, and the minimum flow rate, which is the minimum value of the intake flow rate in the cycle, is in a large state. The operation mode switching process selects the operation value of the intake air amount obtained by the second operation process when it is determined that the intake pulsation is in a large state.)

1. An engine control device applied to an engine having an air flow meter that detects an intake air flow rate in an intake passage, the engine control device controlling an operation of the engine by operating an actuator provided in the engine, wherein the engine control device is configured to perform:

a first calculation process of calculating an intake air amount to be introduced into a cylinder of the engine and detecting the intake air amount based on a detection result of the airflow meter;

a second calculation process of calculating the intake air amount based on at least one of a detected value of an intake pipe pressure and a throttle opening degree, without using a detection result of the air flow meter;

a determination process of determining whether or not an intake pulsation is in a large state based on the intake air flow rate detected by the airflow meter, and determining that the intake pulsation is in a large state when a difference between an average flow rate, which is an average value of the intake air flow rate in a cycle of the intake pulsation, and a minimum flow rate, which is a minimum value of the intake air flow rate in the cycle, is in a large state; and

and an operation manner switching process of selecting the operation value of the intake air amount obtained by the first operation process as the operation value of the intake air amount used for determining the operation amount of the actuator when it is not determined by the determination process that the intake air pulsation is in a large state, and selecting the operation value of the intake air amount obtained by the second operation process as the operation value of the intake air amount used for determining the operation amount of the actuator when it is determined by the determination process that the intake air pulsation is in a large state.

2. The engine control apparatus according to claim 1,

the determination process confirms that the difference between the average flow rate and the minimum flow rate is in a large state, based on the fact that the difference obtained by subtracting the instantaneous value of the intake air flow rate detected by the airflow meter from the average flow rate becomes a large value.

3. The engine control apparatus according to claim 1 or 2,

the determination process obtains a quotient obtained by dividing a difference between the average flow rate and the minimum flow rate by the average flow rate as a value of a pulsation rate, and determines that the intake pulsation is in a large state when the pulsation rate exceeds a predetermined pulsation determination value.

4. The engine control device according to any one of claims 1 to 3,

the determination process determines that the intake pulsation is not in a large state when the throttle opening is determined to be an opening smaller than a predetermined low opening determination value when it is determined that the intake pulsation is in a large state.

5. The engine control device according to any one of claims 1 to 4,

the determination process determines that intake pulsation is not in a large state when the intake pipe pressure is a pressure less than a predetermined low pressure determination value when it is determined that intake pulsation is in a large state.

6. The engine control device according to any one of claims 1 to 5,

the determination process determines that the intake pulsation is in a large state when a state in which the difference between the average flow rate and the minimum flow rate is large continues for two cycles of the intake pulsation.

7. An engine control method applied to an engine having an air flow meter that detects an intake air flow rate in an intake passage, the engine control method performing operation control of the engine by operating an actuator provided in the engine, the engine control method comprising:

calculating an intake air amount introduced into a cylinder of the engine based on a detection result of the air flow meter;

calculating the intake air amount based on at least one of a detected value of an intake pipe pressure and a throttle opening degree without using a detection result of the air flow meter;

determining whether or not an intake pulsation is in a large state based on the intake air flow rate detected by the airflow meter, and determining that the intake pulsation is in a large state when a difference between an average flow rate, which is an average value of the intake air flow rate in a cycle of the intake pulsation, and a minimum flow rate, which is a minimum value of the intake air flow rate in the cycle, is in a large state; and

when it is not determined that the intake pulsation is large, the calculated value of the intake air amount obtained by calculation based on the detection result of the airflow meter is selected as the calculated value of the intake air amount used for determining the operation amount of the actuator, and when it is determined that the intake pulsation is large, the calculated value of the intake air amount obtained by calculation based on at least one of the detection value of the intake pipe pressure and the throttle opening degree is selected as the calculated value of the intake air amount used for determining the operation amount of the actuator.

8. A non-transitory computer-readable storage medium storing a program for causing a processing device to execute an engine control process applied to an engine having an air flow meter that detects an intake air flow rate of an intake passage, the engine control process controlling operation of the engine by operating an actuator provided in the engine, the engine control process comprising:

calculating an intake air amount introduced into a cylinder of the engine based on a detection result of the air flow meter;

calculating the intake air amount based on at least one of a detected value of an intake pipe pressure and a throttle opening degree without using a detection result of the air flow meter;

determining whether or not an intake pulsation is in a large state based on the intake air flow rate detected by the airflow meter, and determining that the intake pulsation is in a large state when a difference between an average flow rate, which is an average value of the intake air flow rate in a cycle of the intake pulsation, and a minimum flow rate, which is a minimum value of the intake air flow rate in the cycle, is in a large state; and

when it is not determined that the intake pulsation is large, the calculated value of the intake air amount obtained by calculation based on the detection result of the airflow meter is selected as the calculated value of the intake air amount used for determining the operation amount of the actuator, and when it is determined that the intake pulsation is large, the calculated value of the intake air amount obtained by calculation based on at least one of the detection value of the intake pipe pressure and the throttle opening degree is selected as the calculated value of the intake air amount used for determining the operation amount of the actuator.

Technical Field

The present disclosure relates to an engine control device that calculates an intake air amount introduced into a cylinder and performs operation control of an engine by operating an actuator such as an injector based on a calculated value of the intake air amount.

Background

The control of the operating state of the engine is performed by operating an actuator such as an injector or a throttle. For example, the air-fuel ratio of the air-fuel mixture burned in the cylinder is controlled by "determining a fuel injection amount necessary for bringing the air-fuel ratio to a target value based on the intake air amount introduced into the cylinder, and operating the injector so as to inject the fuel of the determined fuel injection amount". In such an improvement in the control accuracy of the engine control performed by determining the operation amount of the actuator based on the intake air amount, it is necessary to precisely grasp the intake air amount.

Conventionally, as a calculation method of the intake air amount, 3 methods of a mass flow method, a speed density method, and a throttle speed method are known. In the mass flow method, the intake air amount is calculated from the intake air flow rate detected by an air flow meter provided in a portion of the intake passage upstream of the throttle valve. In the speed density method, an intake pipe pressure is detected by an intake pipe pressure sensor provided in a portion of an intake passage on the downstream side of a throttle valve, and an intake air amount is calculated from an intake air flow rate estimated based on the intake pipe pressure and an engine speed. In the throttle speed system, the intake air amount is calculated from an intake air flow rate estimated based on the throttle opening and the engine speed.

Generally, of these 3 calculation methods, the mass flow method can calculate the intake air amount at the time of steady operation of the engine with the highest accuracy. However, since each cylinder of the engine intermittently sucks intake air in accordance with opening and closing of the intake valve, the flow of intake air in the intake passage is accompanied by pulsation. Further, since the influence of such intake pulsation is also expressed in the detection value of the airflow meter, the intake air amount may be calculated with higher accuracy in the speed density method and the throttle speed method than in the mass flow method in the operating region of the engine where intake pulsation is large.

In contrast, conventionally, as disclosed in japanese patent application laid-open No. 1-265122, an engine control device has been proposed that calculates an intake air amount by switching a calculation method according to the magnitude of intake air pulsation. In the engine control device of this document, it is determined whether or not the intake pulsation is in a large state based on the output of the air flow meter. When it is determined that the intake pulsation is not in a large state, the intake air amount is calculated by the mass flow rate method, and when it is determined that the intake pulsation is in a large state, the intake air amount is calculated by the throttle speed method.

However, depending on the operating conditions of the engine, the intake air may flow back in the intake passage temporarily due to the intake pulsation. In particular, in an engine in which the atkinson cycle is realized by setting the closing timing of the intake valve to a timing later than compression bottom dead center, the intake air is pushed back into the intake passage from the cylinder after compression bottom dead center, and therefore, the backflow of the intake air is likely to occur.

On the other hand, the output characteristic of the air flow meter is set to be nonlinear with respect to the intake air flow rate, and the detection accuracy of the air flow meter is set to be higher as the flow rate range is used more frequently. Therefore, in a flow rate region where the flow of intake air is reversed, the detection error of the air flow meter increases. Therefore, if a reverse flow of intake air occurs, the magnitude of the intake pulsation cannot be accurately determined, and there is a possibility that the manner of calculating the intake air amount cannot be appropriately switched.

Disclosure of Invention

Hereinafter, each side of the present disclosure will be described.

As side 1 provided by one side of the present disclosure, an engine control device is applied to an engine having an air flow meter that detects an intake air flow rate of an intake passage, and operation control of the engine is performed by operating an actuator provided to the engine. The engine control device performs a first arithmetic operation for calculating an intake air amount to be introduced into a cylinder of the engine based on an intake air flow rate detected by the air flow meter, and detects the intake air amount based on a detection result of the air flow meter. The second calculation process calculates the intake air amount based on at least one of the detected value of the intake pipe pressure and the throttle opening degree, without using the detection result of the air flow meter. The determination process is a process of determining whether or not the intake pulsation is in a large state based on the intake air flow rate detected by the airflow meter, and determines that the intake pulsation is in a large state when it is confirmed that the difference between the average flow rate, which is the average value of the intake air flow rate in a cycle of the intake pulsation, and the minimum flow rate, which is the minimum value of the intake air flow rate in the cycle, is large. The operation manner switching process selects the operation value of the intake air amount obtained by the first operation process as the operation value of the intake air amount used for determining the operation amount of the actuator when it is not determined by the determination process that the intake air pulsation is in a large state, and selects the operation value of the intake air amount obtained by the second operation process as the operation value of the intake air amount used for determining the operation amount of the actuator when it is determined by the determination process that the intake air pulsation is in a large state.

In the first calculation process in the engine control device, the intake air amount is calculated by a mass flow method based on the detected value of the intake air flow rate of the air flow meter. In the second calculation process, the intake air amount is calculated based on the speed density pattern of the detected value of the intake pipe pressure or the throttle speed pattern. When the intake pulsation is in a large state, the accuracy of detecting the intake air flow rate of the air flow meter deteriorates, and the accuracy of calculating the intake air amount in the mass flow system decreases.

Then, in the engine control device, a determination process for determining whether or not the intake pulsation is in a large state is performed. The method of calculating the intake air amount used for determining the operation amount of the actuator is switched according to the magnitude of the intake air pulsation so that the mass flow rate method is performed when the intake air pulsation is small and the speed density method or the throttle speed method is performed when the intake air pulsation is large.

The magnitude of the intake pulsation is determined from the detection result of the intake air flow rate of the air flow meter. For example, the full amplitude of the fluctuation waveform of the intake air flow rate, the peak-side half amplitude thereof, or the valley-side half amplitude thereof can be obtained as the evaluation value of the magnitude of the intake pulsation from the detection result of the air flow meter. The air flow meter has a nonlinear output characteristic with respect to the intake air flow rate, and the detection error of the air flow meter increases in the counter flow region, which is a flow rate region where the intake air flow rate becomes a negative value. Therefore, when the intake pulsation reaching the reverse flow region occurs, an error occurs in the full amplitude, the half amplitude on the peak side, and the half amplitude on the valley side, which are obtained from the detection result of the air flow meter.

On the other hand, when the state is changed from the state in which the intake pulsation is generated in the range not reaching the reverse flow region to the state in which the intake pulsation is increased to reach the reverse flow region, the half amplitude increase rate on the valley side is larger than the half amplitude increase rate on the peak side. Therefore, the half amplitude on the valley side when the intake pulsation increases to reach the reverse flow field indicates a significant increase in the amount of error exceeding the air flow meter. Therefore, even when intake pulsation that reaches the reverse flow region occurs, the magnitude of the intake pulsation can be accurately grasped to some extent by observing the half amplitude on the bottom side of the fluctuation waveform of the intake flow rate detected by the airflow meter.

In contrast, in the determination process in the engine control device, when it is confirmed that the half amplitude on the bottom side of the fluctuation waveform of the intake air flow rate, which is the difference between the average flow rate and the minimum flow rate in the cycle of the intake air pulsation, is in a large state, it is determined that the intake air pulsation is in a large state. Therefore, even when the intake pulsation reaching the reverse flow region occurs, the magnitude of the intake pulsation is accurately determined, and therefore the method of calculating the intake air amount can be appropriately switched.

Hereinafter, the intake air flow rate detected by the air flow meter is referred to as an AFM detection flow rate. Since the minimum flow rate is not determined until the cycle of the intake pulsation rotates once, even if the intake pulsation increases, the cycle in which the intake pulsation occurs at maximum may be delayed in time until the increase in the intake pulsation can be confirmed as an increase in the difference between the average flow rate and the minimum flow rate. On the other hand, in the cycle of the intake air pulsation, the difference obtained by subtracting the instantaneous value of the AFM detection flow rate from the average flow rate is always equal to or less than the difference between the average flow rate and the minimum flow rate. Thus, at the time point when the difference obtained by subtracting the instantaneous value of the AFM detection flow rate from the average flow rate becomes a large value, it is ensured that the difference between the average flow rate and the minimum flow rate becomes a large value. In view of the above, as the side 2, in the determination process in the engine control device, it can be confirmed that the difference between the average flow rate and the minimum flow rate is large, based on the fact that the difference obtained by subtracting the instantaneous value of the intake air flow rate detected by the air flow meter from the average flow rate becomes large. Thus, it can be quickly determined that the intake pulsation has changed from a small state to a large state.

When an error occurs in the first calculated intake air amount due to the intake pulsation, the relative magnitude of the error with respect to the value of the calculated intake air amount may become a problem as compared with the absolute magnitude of the error. In this case, as the side 3, the determination process in the engine control device may obtain a quotient obtained by dividing a difference between the average flow rate and the minimum flow rate by the average flow rate as a value of the pulsation rate, and determine that the intake pulsation is in a large state when the pulsation rate exceeds a predetermined pulsation determination value.

When the throttle opening is smaller than a certain degree, large intake pulsation is not generated beyond the allowable range and the accuracy of calculation of the first intake air amount is lowered. In view of the above, as the side surface 4, the determination process in the engine control device may determine that the intake pulsation is not in a large state when the throttle opening is determined to be an opening smaller than a predetermined low opening determination value when the intake pulsation is determined to be in a large state. In such a case, when the throttle valve is rapidly closed and the intake pulsation is reduced, it may be determined that the intake pulsation is reduced before the influence occurs in the difference between the average flow rate and the minimum flow rate. This makes it possible to quickly determine that the intake pulsation has changed from a large state to a small state. Further, as the throttle opening degree becomes smaller, the intake pipe pressure becomes lower. Therefore, as the side surface 5, in the determination process in the engine control device, it may be determined that the intake pulsation is not in a large state when the intake pipe pressure is a pressure smaller than a predetermined low pressure determination value when it is determined that the intake pulsation is in a large state. In this case, it can be also quickly determined that the intake pulsation has changed from the large state to the small state.

A case is considered in which a value that temporarily indicates a flow rate lower than the original flow rate due to superposition of noise on an output signal of the air flow meter or the like is obtained as a value of the minimum flow rate. In this case, even if the intake pulsation does not actually increase, the difference between the average flow rate and the minimum flow rate may increase, and it may be erroneously determined that the intake pulsation is in a large state. Since the influence of noise is temporary, as the side surface 6, the determination process in the engine control device may determine that the intake pulsation is in a large state when the state in which the difference between the average flow rate and the minimum flow rate is large continues for two cycles of the intake pulsation. This can suppress the above-described erroneous determination.

The side surface 7 is embodied as an engine control method for executing various processes described in any of the above-described side surfaces.

The side 8 is embodied as a non-transitory computer-readable recording medium storing a program for causing a processing device to execute various processes described in any of the above-described sides.

Drawings

Fig. 1 is a diagram schematically showing the configuration of an engine control device according to a first embodiment.

Fig. 2 is a control block diagram showing the flow of the process related to the fuel injection amount control executed by the engine control device.

Fig. 3 is an explanatory diagram of a calculation scheme of the pulse rate calculated by the engine control device in the determination process.

Fig. 4 is a diagram showing changes in AFM detection flow rates when a reverse flow occurs and when a reverse flow does not occur.

Fig. 5 is a diagram showing a configuration for setting a pulsation determination value in the engine control device according to the second embodiment.

Fig. 6 is a flowchart of a pulsation determination process performed by the engine control device of the third embodiment.

Fig. 7 is a time chart showing an example of the pulsation determination of the engine control device, where (a) shows a change in the value of the AFM detection flow rate, (b) shows a change in the value of the pulsation rate, (c) shows a change in the state of the large pulsation domain determination flag, and (d) shows a change in the value of the counter.

Fig. 8 is a flowchart of a forced determination shut-down process performed by the engine control device of the fourth embodiment.

Fig. 9 is a flowchart of a pulsation determination process performed by the engine control device of the fifth embodiment.

Detailed Description

(first embodiment)

A first embodiment of an engine control device will be described below with reference to fig. 1 to 4. First, the configuration of the engine control device according to the present embodiment will be described with reference to fig. 1. The engine control device of the present embodiment is applied to a multi-cylinder engine for vehicle mounting. Fig. 1 shows only one of the cylinders provided in the engine.

As shown in fig. 1, an air cleaner 12 for filtering dust and the like in intake air is provided in the most upstream portion of an intake passage 11 of an engine 10 to which the engine control device according to each embodiment is applied. An air flow meter 13 for detecting the intake air flow rate is provided in a portion of the intake passage 11 on the downstream side of the air cleaner 12.

A throttle valve 14, which is a valve for adjusting the intake air flow rate, is provided in a portion of the intake passage 11 on the downstream side of the airflow meter 13. A throttle motor 15 for driving the throttle valve 14 to open and close and a throttle sensor 16 for detecting the opening degree of the throttle valve 14 are provided in the vicinity of the throttle valve 14. Further, an intake pipe pressure sensor 17 that detects the pressure of intake air flowing inside is provided in a portion of the intake passage 11 on the downstream side of the throttle valve 14. In the following description, the opening degree of the throttle valve 14 is referred to as a throttle valve opening degree TA. The pressure of the intake air detected by the intake pipe pressure sensor 17 is referred to as an intake pipe pressure PM.

An injector 18 that injects fuel into intake air is provided in a portion of the intake passage 11 on the downstream side of the intake pipe pressure sensor 17. The intake passage 11 is connected to a combustion chamber 20 via an intake valve 19. The combustion chamber 20 is provided with an ignition device 21 that ignites an air-fuel mixture of intake air and fuel by spark discharge.

The combustion chamber 20 is connected to an exhaust passage 23 via an exhaust valve 22. An air-fuel ratio sensor 24 for detecting the air-fuel ratio of the air-fuel mixture burned in the combustion chamber 20 and a catalyst device 25 for purifying the exhaust gas are provided in the exhaust passage 23. The injector 18, the intake valve 19, the combustion chamber 20, the ignition device 21, and the exhaust valve 22 among the components of the engine 10 are provided individually for each cylinder of the engine 10.

The engine 10 is controlled by an electronic control unit 26 as an engine control device. The electronic control unit 26 includes an arithmetic processing circuit 27 that performs various arithmetic processes related to engine control, and a memory 28 in which programs and data for control are stored. Detection signals of the airflow meter 13, the throttle sensor 16, the intake pipe pressure sensor 17, and the air-fuel ratio sensor 24 are input to the electronic control unit 26. Further, detection signals of the crank angle sensor 30, the accelerator pedal sensor 32, the vehicle speed sensor 33, the water temperature sensor 34, the intake air temperature sensor 35, the atmospheric pressure sensor 36, and the like are also input to the electronic control unit 26. Crank angle sensor 30 is a sensor for detecting crank angle CRNK, which is a rotation angle of crankshaft 29, which is an output shaft of engine 10, and accelerator pedal sensor 32 is a sensor for detecting an accelerator pedal opening ACCP, which is an amount of depression of accelerator pedal 31. The vehicle speed sensor 33 is a sensor that detects a vehicle speed V that is a traveling speed of a vehicle on which the engine 10 is mounted, the water temperature sensor 34 is a sensor that detects a cooling water temperature THW of the engine 10, the intake air temperature sensor 35 is a sensor that detects an intake air temperature THA that is a temperature of intake air drawn into the intake passage 11, and the atmospheric pressure sensor 36 is a sensor that detects an atmospheric pressure PA.

The electronic control unit 26 determines the operation amounts of actuators such as the throttle motor 15, the injector 18, and the ignition device 21 based on detection signals of these sensors, and controls the operation state of the engine 10 by operating these actuators. The electronic control unit 26 calculates the engine speed NE based on the detection result of the crank angle CRNK by the crank angle sensor 30.

The electronic control unit 26 controls the amount of fuel injected by the injector 18 of each cylinder, that is, controls the fuel injection amount as part of engine control. In the fuel injection amount control, the electronic control unit 26 first calculates an intake air amount to be introduced into each cylinder of the engine 10. Next, the electronic control unit 26 calculates a quotient obtained by dividing the calculated value of the intake air amount by the stoichiometric air-fuel ratio as a value indicating the injection amount, and controls the fuel injection amount by operating the injector 18 of each cylinder so as to inject the fuel of the indicated injection amount.

Fig. 2 shows a flow of the processing of the electronic control unit 26 relating to such fuel injection amount control. As shown in the figure, the fuel injection amount control in the engine control device of the present embodiment is performed by each of the first arithmetic processing P1, the second arithmetic processing P2, the determination processing P3, the arithmetic manner switching processing P4, and the operation processing P5.

First, in the first calculation process P1, the intake air amount introduced into the cylinder of the engine 10 is calculated based on the AFM detection flow rate GA and the engine speed NE. That is, in the first calculation process P1, the mass flow type intake air amount is calculated based on the output of the airflow meter 13. In the following description, the intake air amount calculation value in the first calculation process P1 will be referred to as a first intake air amount calculation value MC 1.

In the second calculation process P2, the intake air amount is calculated based on the throttle opening degree TA and the engine speed NE. That is, in the second calculation process P2, the throttle speed type intake air amount is calculated based on the throttle opening TA. In the following description, the intake air amount calculation value in the second calculation process P2 will be referred to as a second intake air amount calculation value MC 2.

In the intake passage 11 of the engine 10, intermittent intake air flows into the combustion chamber 20 in accordance with the opening and closing of the intake valve 19, thereby generating pressure fluctuations of the intake air. Pressure fluctuations caused by opening and closing of the intake valve 19 are propagated through the intake passage 11 in the upstream direction, and as a result, are propagated to the entire intake passage 11. In the determination process P3, it is determined whether or not the pressure fluctuation of the intake air, that is, the intake air pulsation, is large at the installation location of the airflow meter 13 in the intake passage 11. In the following description, the determination of whether or not the intake pulsation is large is referred to as a pulsation determination.

The pulsation determination in the determination process P3 is performed by the following scheme. In the determination process P3, first, the minimum flow GMIN and the average flow GAVE are obtained based on the AFM detection flow GA. As shown in fig. 3, the minimum flow rate GMIN represents the minimum value of the AFM detection flow rate GA in the period T0 of the intake air pulsation, and the average flow rate GAVE represents the average value of the AFM detection flow rate GA in the period T0 of the intake air pulsation. The values of the minimum flow GMIN and the average flow GAVE are updated every period T0 of the intake pulsation. In the case of a 4-stroke engine in which the ignition sequence of each cylinder makes one rotation every 2 rotations of the crankshaft 29, the period T0 of the intake pulsation is a quotient obtained by dividing 720 ° ca by the number of cylinders of the engine 10.

Next, in the determination process P3, a quotient obtained by dividing the difference obtained by subtracting the minimum flow rate GMIN from the average flow rate GAVE by the average flow rate GAVE is obtained as the value of the pulse rate PR. On the other hand, in the determination process P3, the pulsation determination value PR0 is obtained based on the engine speed NE. In the determination process P3, when the pulsation rate PR is equal to or greater than the pulsation determination value PR0, it is determined that the intake pulsation is in a large state. More specifically, when the pulse rate PR is equal to or greater than the pulse determination value PR0, a large pulse domain determination flag, which is a flag indicating the result of pulse determination, is set, and when the pulse rate PR is smaller than the pulse determination value PR0, the large pulse domain determination flag is cleared.

The higher the engine speed NE is, the greater the number of times of intake to each cylinder of the engine 10 per unit time is. Simply considered, the intake air amount of each cylinder is a quotient obtained by dividing the intake air flow rate by the number of times of intake air per unit time. Thus, even if the pulse rate PR is the same, the error in the first calculated intake air amount MC1 due to the influence thereof is larger as the engine speed NE is lower. Reflecting this, the value of the pulsation determination value PR0 is set to be smaller when the engine speed NE is low than when the engine speed NE is high.

In the operation method switching process P4, the operation value of the intake air amount to be handed over to the operation process P5, out of the 2 operation values of the intake air amount, the first intake air amount operation value MC1 and the second intake air amount operation value MC2, is switched in accordance with the result of the pulsation determination in the determination process P3. Specifically, when the large pulsation domain flag is in the clear state, the first intake air amount calculated value MC1 is handed over to operation process P5 as the calculated value of the intake air amount, and when the large pulsation domain flag is in the on state, the second intake air amount calculated value MC2 is handed over to operation process P5 as the calculated value of the intake air amount.

In the operation process P5, the command value of the fuel injection amount of the injector 18, that is, the value of the command injection amount Q is calculated based on the calculated value of the intake air amount received from the calculation method switching process P4, and the injector 18 of each cylinder is operated so as to inject the fuel of the value of the command injection amount Q. More specifically, in the operation process P5, first, a quotient obtained by dividing the calculated value of the intake air amount received from the operation system switching process P4 by the stoichiometric air-fuel ratio is calculated as the value of the basic injection amount QBSE. Then, a value obtained by applying correction such as air-fuel ratio feedback correction based on the detection result of the air-fuel ratio sensor 24 to the base injection amount QBSE is set as a value indicating the injection amount Q, and the injector 18 is operated based on the value.

The operation and effect of the present embodiment will be described.

In the intake passage 11 of the engine 10, an intake pulsation is generated by intermittently opening the intake valve 19. When such intake pulsation increases, the detection accuracy of the airflow meter 13 is reduced due to the influence of the intake pulsation.

In contrast, in the present embodiment, the intake air amount is calculated by the mass flow rate method based on the output of the airflow meter 13 in the first calculation process P1, and the intake air amount is calculated by the throttle speed method based on the throttle opening degree TA in the second calculation process P2. If the detection accuracy of the airflow meter 13 decreases, the calculation accuracy of the intake air amount by the first calculation process P1 also decreases. Therefore, if the instructed injection amount Q of the injector 18 is determined using the first intake air amount calculation value MC1 based on the first calculation process P1 even when the intake pulsation becomes large, the control accuracy of the fuel injection amount deteriorates. In the present embodiment, the indicated injection amount Q is determined using the first calculated intake air amount MC1 calculated in the first calculation process P1 when the intake pulsation is small, while the indicated injection amount Q is determined using the second calculated intake air amount MC2 calculated in the second calculation process P2 when the intake pulsation is large. As described above, in the present embodiment, when the intake pulsation is large, the operation mode of the intake air amount used for determining the fuel injection amount is switched from the mass flow rate mode to the throttle speed mode, thereby suppressing deterioration of the control accuracy of the fuel injection amount due to increase of the intake pulsation.

On the other hand, as the quantities indicating the amplitude of the intake pulsation, there are the full amplitude Af, the peak-side half amplitude Ap, and the valley-side half amplitude Ab shown in fig. 3. The full amplitude Af of the intake pulsation represents the difference between the maximum flow rate GMAX and the minimum flow rate GMIN, which is the minimum value thereof, and the half amplitude Ap on the peak side represents the difference between the maximum flow rate GMAX and the average flow rate GAVE. The half amplitude Ab on the bottom side represents the difference between the average flow rate GAVE and the minimum flow rate GMIN. The maximum flow rate GMAX is the maximum value of the AFM detection flow rate GA in the period T0 of the intake air pulsation.

In contrast, in the present embodiment, in the determination process P3, the pulsation determination for switching the operation method of the intake air amount is performed based on the pulsation rate PR obtained from the AFM detection flow rate GA. As described above, the value of the pulse rate PR is obtained as a quotient obtained by dividing the difference between the average flow rate GAVE and the minimum flow rate GMIN in the period T0 of the intake air pulsation by the average flow rate GAVE. In the present embodiment, the pulsation determination is performed using the half amplitude Ab on the bottom side of the intake pulsation as a parameter for evaluating the amplitude of the intake pulsation.

As parameters for evaluating the magnitude of the intake pulsation, the full amplitude Af and the half amplitude Ap on the peak side of the intake pulsation may be used. In contrast, in the present embodiment, the bottom-side half-amplitude Ab is used as a parameter for evaluating the amplitude of the intake air pulsation in the pulsation determination, for the following reason.

In fig. 4, the waveform of the AFM detected flow rate GA when the engine 10 is operated in a range where the AFM detected flow rate GA is not 0 or less, that is, in a state where the intake pulsation does not reach the reverse flow region is shown by a solid line. In the following description, a state in which intake pulsation is generated in a range not reaching the reverse flow field is referred to as a reverse flow non-generation state. In fig. 4, the waveform of the AFM detection flow rate GA when the engine speed NE and the intake air amount are adjusted so as to be kept constant from the above-described operation state when the backflow is not generated, the valve timing of the intake valve 19 is retarded, and the intake pulsation increases until the upstream region is reached is shown by the two-dot chain line. In the following description, a state in which the intake pulsation increases until the intake pulsation reaches the reverse flow field is referred to as a reverse flow generation state. In the case of the transition from the backflow non-generating state to the backflow generating state in the above-described manner, since the engine speed NE and the intake air amount are constant, the average flow rate GAVE is kept at the same value.

In addition, in the transition from the backflow non-generating state to the backflow generating state in the above-described aspect, the throttle opening degree TA is increased. In a state where the throttle opening degree TA is large and the flow path area of the intake air at the throttle valve 14 is enlarged, the pressure variation generated by opening and closing of the intake valve 19 is easily transmitted to the air flow meter 13. Therefore, when the throttle opening degree TA is increased at the time of transition from the backflow non-generating state to the backflow generating state, the intake pulsation increases. The increase width of the bottom half amplitude Ab at the time of increase of the intake pulsation at this time is larger than the increase width of the peak half amplitude Ap. Therefore, in the backflow occurrence state, the bottom half-amplitude Ab is larger than the peak half-amplitude Ap. Thus, of the full amplitude Af, the peak-side half amplitude Ap, and the valley-side half amplitude Ab, the valley-side half amplitude Ab is the highest in the rate of increase of the value at the transition from the non-backflow state to the backflow state.

On the other hand, the air flow meter 13 has a nonlinear output characteristic with respect to the intake air flow rate. The detection accuracy of the air flow meter 13 is designed to be higher in a flow rate range with a high frequency of use. Since the backflow of the intake air occurs in a limited situation, the detection error of the airflow meter 13 becomes large in a backflow region that is a flow rate region in which the intake air flow rate has a negative value. Thus, when the full amplitude Af, the peak-side half amplitude Ap, and the valley-side half amplitude Ab are calculated based on the AFM detection flow rate GA, an error occurs in each of these calculated values in a state where the intake pulsation is increased to reach the reverse flow region. In this case as well, the rate of increase of the value of the valley side half amplitude Ab with respect to the increase of the intake pulsation is large, and therefore, the value of the valley side half amplitude Ab increases significantly as long as the intake pulsation increases, regardless of the error. Thus, when considering the occurrence of intake air pulsations that reach the reverse flow field, it is possible to achieve appropriate pulsation determination using the bottom-side half amplitude Ab, as compared to using the full amplitude Af and the peak-side half amplitude Ap.

Incidentally, the air flow meter 13 is of a type capable of detecting the flow direction of intake air and of a type incapable of detecting the flow direction, that is, a type that simply detects the flow rate of intake air regardless of forward flow or reverse flow. The waveform of the AFM measured flow rate GA shown in fig. 4 is a waveform of an air flow meter capable of measuring the flow direction of intake air, and the AFM measured flow rate GA in the case of reverse flow has a negative value. On the other hand, in the case where an air flow meter in which the flow direction of the intake air cannot be detected is used as the air flow meter 13, among the full amplitude Af, the peak-side half amplitude Ap, and the valley-side half amplitude Ab, the valley-side half amplitude Ab is the one with the largest rate of increase in the transition from the non-backflow state to the backflow state. Therefore, even when an air flow meter that cannot detect the flow direction of intake air is used, the pulsation determination of intake air can be appropriately performed using the half amplitude Ab on the valley side as compared with using the full amplitude Af and the half amplitude Ap on the peak side.

The engine control device according to the present embodiment described above can provide the following effects.

(1) In the present embodiment, when it is determined that the intake pulsation is not in a large state, the first calculated intake air amount MC1 calculated by the mass flow rate method is used as the calculated value of the intake air amount used in the fuel injection amount control, and when it is determined that the intake pulsation is in a large state, the second calculated intake air amount MC2 calculated by the throttle speed method is used as the calculated value of the intake air amount used in the fuel injection amount control. Therefore, it is possible to suppress a decrease in the control accuracy of the fuel injection amount when the calculation accuracy of the intake air amount of the mass flow system decreases due to an increase in the intake pulsation.

(2) In the present embodiment, it is determined that the intake pulsation is in a large state when the difference between the average flow rate GAVE, which is the average value of the AFM detected flow rates GA, and the minimum flow rate GMIN, which is the minimum value of the AFM detected flow rates GA, is large. Therefore, even when the intake air pulsation reaches the reverse flow region where the detection error of the airflow meter 13 becomes large, the pulsation determination can be accurately performed, and therefore the calculation method of the intake air amount can be appropriately switched.

(second embodiment)

Next, a second embodiment of the engine control device will be described in detail with reference to fig. 5. In this embodiment and the embodiments described later, the same reference numerals are given to the same components as those of the above-described embodiments, and detailed description thereof will be omitted.

Propagation of the pressure variation of the intake air via the throttle valve 14 is greatly affected by the throttle opening degree TA. Therefore, if the small change in the throttle opening degree TA is repeated frequently, the intake pulsation increases and decreases frequently, the intake air amount calculation method is frequently switched, and the engine control may become unstable. In contrast, in the engine control device of the present embodiment, a delay is set in the pulsation determination value PR0 in order to suppress the frequency of switching the operation method of the intake air amount. That is, in the present embodiment, 2 determination values, that is, the setup determination value PRs used when the large pulsation domain determination flag is in the clear state and the clear determination value PRC used when the large pulsation domain determination flag is in the setup state are prepared as the pulsation determination value PR 0. The setup determination value PRS and the purge determination value PRC are both determination values that are set based on the engine speed NE.

Fig. 5 shows the relationship of the engine speed NE with the set determination value PRS and the clear determination value PRC. The value of the setup determination value PRS is set in the same manner as the pulsation determination value PR0 in the first embodiment. On the other hand, as shown in the figure, the purge determination value PRC at each engine speed NE is set to a value smaller than the set determination value PRS at the same engine speed NE. In the determination process P3 in the engine control device according to the present embodiment, the pulsation determination is performed by setting the setup determination value PRS to the value of the pulsation determination value PR0 when the large pulsation domain determination flag is in the clear state, and setting the clear determination value PRC to the value of the pulsation determination value PR0 when the large pulsation domain determination flag is in the set state.

The engine control device of the present embodiment can also achieve the effects (1) and (2) described above. Further, according to the engine control device of the present embodiment, since the frequency of switching the intake air amount calculation method can be suppressed, the engine control can be easily stabilized.

(third embodiment)

Next, a third embodiment of the engine control device will be described with reference to fig. 6 and 7.

As described above, in the first and second embodiments, the pulsation determination is performed based on the half amplitude Ab on the valley side. The bottom half-amplitude Ab is determined as the difference between the average flow rate GAVE, which is the average value of the AFM measured flow rates GA in the period T0 of the intake pulse, and the minimum flow rate GMIN, which is the minimum value of the AFM measured flow rates GA in the period T0. The values of the average flow rate GAVE and the minimum flow rate GMIN are updated only every cycle T0 of the intake pulse. Therefore, the delay of the period T0 occurs at the maximum in time from when the intake pulsation actually increases until the operation mode for switching the intake air amount from the mass flow rate mode to the throttle speed mode. In contrast, in the present embodiment, the delay in switching the above-described manner of calculating the intake air amount is suppressed by performing the determination process P3 in accordance with the following embodiment.

Fig. 6 is a flowchart showing a pulsation determination process performed in the determination process P3 by the engine control device according to the present embodiment. The electronic control unit 26 repeatedly executes the pulsation determination process shown in fig. 6 every predetermined crank angle during operation of the engine 10. Incidentally, the execution interval T1 of the pulsation determination processing is set to a quotient obtained by dividing the cycle T0 of the intake pulsation by an integer M of 2 or more. That is, the pulsation determination process is executed M times in the period T0 of intake pulsation.

When the pulsation determination process is started, first, it is determined whether or not the large pulsation domain determination flag is in a clear state in step S100. If the large ripple domain determination flag is in the clear state (yes in S100), the process proceeds to step S110, and if the large ripple domain determination flag is in the set state (no in S100), the process proceeds to step S180.

When the process proceeds to step S110, the value of the counter CNT is cleared to 0 in this step S110. In the next step S120, the current value of the AFM detection flow rate GA is acquired. Then, in step S130, the corrected moving average MMA of the AFM detection flow rate GA is obtained, and this value is set as the value of the average flow rate GAVE 1. The corrected moving average MMA of the AFM detection flow rate GA is obtained by updating the value based on the formula (1). Incidentally, MMA [ i-1] in the formula (1) represents a value of the corrected moving average MMA before the update, and MMA [ i ] represents a value of the corrected moving average MMA after the update. N in the formula (1) is a constant, and an integer of 2 or more is set as the value of N.

MMA[i]←{(N-1)x MMA[i-1]+GA}/N…(1)

Then, in step S140, a quotient obtained by dividing the difference obtained by subtracting the AFM detection flow rate GA from the average flow rate GAVE1 by the average flow rate GAVE1 is obtained as the value of the pulse rate PR 1. In the next step S150, it is determined whether or not the pulsation rate PR1 is larger than the pulsation determination value PR 0. When the pulsation rate PR1 is greater than the pulsation determination value PR0 (yes in S150), the large pulsation domain determination flag is set in step S160, and the present pulsation determination process is ended. When the pulsation rate PR is equal to or less than the pulsation determination value PR0 (no in S150), the large pulsation region determination flag is cleared in step S170, and the present pulsation determination process is terminated.

On the other hand, in the case where the process proceeds to step S180 by determining in step S100 that the large pulsation domain determination flag is in the on state (S100: no), the value of the counter CNT is incremented by 1 in this step S180. Then, in the next step S190, it is determined whether or not the value of the counter CNT is equal to or greater than M, and if the value is equal to or greater than M (S190: yes), the current pulsation determination process is terminated as it is in the above step S110, and if the value is smaller than M (S190: no).

The operation and effect of the present embodiment will be described.

In the first and second embodiments, the pulsation determination is performed after obtaining a quotient obtained by dividing the average flow rate GAVE by the difference obtained by subtracting the minimum flow rate GMIN from the average flow rate GAVE, as a value of the pulsation rate PR. In contrast, in the present embodiment, the pulsation determination is performed after obtaining a quotient obtained by dividing the difference obtained by subtracting the instantaneous value of the AFM detection flow rate GA from the average flow rate GAVE1 by the average flow rate GAVE1 as the value of the pulsation rate PR 1.

Of course, the instantaneous value of the AFM probe flow GA will not be lower than its minimum value, i.e. the minimum flow GMIN. Thus, even when the pulsation rate PR1 obtained from the instantaneous value of the AFM detection flow rate GA exceeds the pulsation determination value PR0 at any instant in the period T0 of the intake pulsation, the pulsation rate PR obtained from the minimum flow rate GMIN in the period T0 naturally exceeds the pulsation determination value PR 0. Thus, by performing the pulsation determination using the instantaneous value of the AFM detection flow rate GA instead of using the minimum flow rate GMIN, it is possible to immediately perform the determination that the intake pulsation is in a large state and the switching of the operation method of the intake air amount corresponding to the increase in the intake pulsation without waiting for the end of the period T0 of the intake pulsation. That is, in the present embodiment, the pulsation determination is performed by confirming that the difference between the average flow rate GAVE and the minimum flow rate GMIN is large, based on the fact that the difference obtained by subtracting the instantaneous value of the AFM detection flow rate GA from the average flow rate GAVE1 becomes large.

Incidentally, in the present embodiment, the corrected moving average of the AFM measured flow rate GA is determined as an approximate value of the average flow rate in the period of the intake air pulsation. Further, this also enables the average flow rate GAVE1 to be updated every time the pulsation determination process is executed.

Fig. 7 shows an example of the embodiment of the pulsation determination in the present embodiment. Fig. 7(a) shows a transition of the value of the AFM detection flow rate GA, fig. 7(b) shows a transition of the value of the pulse rate PR1, fig. 7(c) shows a transition of the value of the large pulse domain determination flag, and fig. 7(d) shows a transition of the value of the counter CNT. Note that, points marked on the graph showing the transition of the pulse rate PR1 in fig. 7(b) indicate the timing of performing the pulsation determination processing based on the pulse rate PR 1.

The large pulsation domain determination flag is in the clear state during the period before time t1 in fig. 7. During this period, the value of the counter CNT is kept at 0. Further, every time the pulsation determination process is executed, that is, every execution interval T1, the calculation of the pulsation rate PR based on the instantaneous value of the AFM detection flow rate GA, which is the value of the AFM detection flow rate GA at that point in time (S130 and S140) and the pulsation determination based on the pulsation rate PR (S150) are performed.

In fig. 7, immediately before time t1, the fluctuation width of the AFM detection flow rate GA, that is, the intake pulsation, is increased. As described above, in the present embodiment, the pulsation rate PR1 is obtained using the instantaneous value of the AFM detection flow rate GA instead of using the minimum flow rate GMIN, and it can be determined that the intake pulsation is in a large state before the minimum flow rate GMIN in the period T0 of the intake pulsation is determined. In the case of fig. 7, at time t1, the pulse rate PR1 exceeds the pulse determination value PR0, and therefore the large pulse domain determination flag is switched from the clear state to the set state.

As described above, when the large ripple domain determination flag is in the on state, the value of the counter CNT is incremented by 1 each time the ripple determination process is performed. In the ripple determination process, if the large ripple domain determination flag is in the on state (S100: no) and the value of the counter CNT is smaller than M (S190: no), the process is terminated without performing substantial ripple determination (S150). As described above, the execution interval T1 of the pulsation determination processing is set to the quotient of the period T0 of the intake pulsation divided by M, and therefore, the period required for the counter CNT to increase from 0 to M is the same as the period T0 of the intake pulsation. Thus, the determination in step S150 in the pulsation determination process, that is, the implementation of the pulsation determination is suspended until the period T0 of the intake pulsation elapses after the large pulsation region determination flag is set.

At time T2 when the time corresponding to the cycle T0 of the intake air pulsation has elapsed from time T1, the counter CNT is incremented to M (S190: yes), and the pulsation determination in step S150 in the pulsation determination processing is performed. Since the value of the pulse rate PR1 obtained based on the instantaneous value of the AFM detection flow rate GA increases and decreases in synchronization with the period T0 of the intake pulsation, the time T2 is the timing at which the pulse rate PR1 increases in the increase and decrease period of the pulse rate PR 1. This is because the time T1 before the period T0 of the time T2 is also the timing at which the pulse rate PR1 increases.

In the case of fig. 7, at time t2, the pulse rate PR1 also exceeds the pulse determination value PR0 (S150: yes), and therefore the large pulse domain determination flag is maintained in the on state (S160). At this point in time, the value of the counter CNT is cleared to 0(S110), and thereafter, 1 is incremented each time the ripple determination process is executed (S180). Thus, while the large pulsation region determination flag is continuously set (S100: NO), pulsation determination (S150) based on the pulsation rate PR1 is performed at intervals of the intake pulsation period T0 (S190: YES).

In the case of fig. 7, the large pulsation region determination flag remains in the on state from the time T3 when the time corresponding to the cycle T0 of the intake pulsation has elapsed from the time T2 until the time T4 when the time corresponding to the cycle T0 of the intake pulsation has further elapsed from the time T3 (S100: no). The intake pulsation is reduced at a timing between time t3 and time t4, and the large pulsation region determination flag is switched from the on state to the off state at time t4 at which the first pulsation determination after the reduction is performed (yes in S100).

The engine control device according to the present embodiment described above can achieve the following effects in addition to the effects (1) and (2) described above.

(3) It can be quickly determined that the intake pulsation has changed from a small state to a large state. As a result, the period during which the accuracy of calculating the intake air amount is reduced due to the increase in the intake pulsation, and the accuracy of controlling the fuel injection amount is reduced is shortened.

(fourth embodiment)

Next, a fourth embodiment of the engine control device will be described with reference to fig. 8. The engine control device of the present embodiment has the same configuration as the engine control device of the third embodiment except that the determination process P3 is performed in addition to the forced determination closing process described later.

In the engine control device according to the third embodiment, a rapid determination can be made as to a change from a small state to a large state of intake pulsation. However, since the pulsation determination is performed every cycle T0 of the intake pulsation while it is determined that the intake pulsation is in a large state, the determination that the intake pulsation has changed from a large state to a small state is delayed by a cycle T0 of the intake pulsation that is most likely to occur in terms of time. In contrast, the engine control device according to the present embodiment performs the forced determination closing process described below in the determination process P3, thereby suppressing the delay in the determination that the intake pulsation has changed from the large state to the small state.

Fig. 8 shows a flowchart of such forced determination closing processing. This process is repeatedly executed by the electronic control unit 26 every predetermined control cycle during operation of the engine 10.

When the present process is started, it is first determined in step S200 whether or not the large ripple domain determination flag is in the set state. If the large ripple domain determination flag is in the on state (yes in S200), the process proceeds to step S210, and if the large ripple domain determination flag is in the off state (no in S200), the present forced determination shutdown process is terminated as it is.

After the process proceeds to step S210, it is determined whether or not the intake pipe pressure PM is less than a predetermined low pressure determination value PM0 in step S210. If the intake pipe pressure PM is less than the low pressure determination value PM0 (yes in S210), the process proceeds to step S230, and if the intake pipe pressure PM is equal to or greater than the low pressure determination value PM0 (no in S210), the process proceeds to step S220.

When the process proceeds to step S220, it is determined whether or not the throttle opening degree TA is smaller than a predetermined low opening degree determination value TA0 in step S220. If the throttle opening degree TA is smaller than the low opening degree determination value TA0 (yes in S220), the process proceeds to step S230, and if the throttle opening degree TA is equal to or greater than the low opening degree determination value TA0 (no in S220), the present forced determination closing process is terminated as it is.

When the process proceeds to step S230, the large ripple region determination flag is cleared in step S230. Then, the present forced determination closing process is ended.

The operation and effect of the present embodiment will be described.

When the throttle opening degree TA is small, the pressure variation of the intake air hardly passes through the throttle valve 14, and therefore the intake pulsation becomes small. Therefore, large intake air pulsations that cause a reduction in the calculation accuracy of the first intake air amount calculation value MC1 occur only in a situation where the throttle opening degree TA is greater than a certain opening degree (a theoretical amount of opening degree). On the other hand, if the throttle opening degree TA is decreased, the intake pipe pressure PM decreases. Therefore, large intake air pulsations to the extent that the calculation accuracy of the first intake air amount calculated value MC1 is degraded are generated only in a situation where the intake pipe pressure PM is greater than a certain pressure.

In the present embodiment, the lower limit value of the throttle opening TA at which a large intake air pulsation occurs to the extent that the accuracy of calculation of the first intake air amount calculation value MC1 is degraded is set to the value of the above-described low opening determination value TA 0. The lower limit value of the intake pipe pressure PM at which large intake pulsation occurs to the extent that the accuracy of calculation of the first intake air amount calculated value MC1 is degraded is set to the value of the above-described low pressure determination value PM 0. When the large pulsation region determination flag is in the on state (yes in S200), if the intake pipe pressure PM decreases to be smaller than the low pressure determination value PM0 (yes in S210), or if the throttle opening degree TA decreases to be smaller than the low opening degree determination value TA0 (yes in S220), the large pulsation region determination flag is cleared at that point (S230). Therefore, when the throttle opening degree TA is suddenly closed as in the case of rapid deceleration, it is possible to quickly determine that the intake pulsation has changed from the large state to the small state without waiting for the result of the pulsation determination based on the pulsation rate PR1 performed every period T0 of the intake pulsation.

The engine control device according to the present embodiment described above can achieve the following effects in addition to the effects (1) and (2) described above.

(4) It can be quickly determined that the intake pulsation has changed from a large state to a small state.

(fifth embodiment)

Next, a fifth embodiment of the engine control device will be described with reference to fig. 9. The engine control device of the present embodiment performs the pulsation determination process in the engine control device of the third embodiment in the scheme shown in fig. 9. In the present embodiment, the pulsation determination processing is also executed by the electronic control unit 26 at the same intervals as in the case of the third embodiment.

When the pulsation determination process is started, first, in step S300, it is determined whether both the large pulsation region determination flag and the provisional determination flag are in the clear state. If both the large ripple domain determination flag and the temporary determination flag are in the clear state (yes in S300), the process proceeds to step S310, and if at least one of the large ripple domain determination flag and the temporary determination flag is in the set state (no in S300), the process proceeds to step S400.

When the process proceeds to step S310, the value of the counter CNT is cleared to 0 in this step S310. In the next step S320, the current value of the AFM detection flow rate GA is acquired. Then, in step S330, the corrected moving average MMA of the AFM detection flow rate GA is obtained, and the value thereof is set to the value of the average flow rate GAVE 1. Then, in step S340, a quotient obtained by dividing the difference obtained by subtracting the AFM detection flow rate GA from the average flow rate GAVE1 by the average flow rate GAVE1 is obtained as the value of the pulse rate PR 1. In the next step S350, it is determined whether or not the pulsation rate PR1 is larger than the pulsation determination value PR 0. When the pulsation rate PR1 is equal to or less than the pulsation determination value PR0 (no in S350), the large pulsation region determination flag is cleared in step S360, and the present pulsation determination process is terminated. On the other hand, when the pulsation rate PR1 is greater than the pulsation determination value PR0 (S350: yes), the process proceeds to step S370.

After the process advances to step S370, in this step S370, it is determined whether the temporary determination flag is in the set state. When the provisional determination flag is in the clear state (no in S370), the provisional determination flag is set in step S380, and the present routine ends. On the other hand, when the temporary determination flag is in the on state (yes in S370), the temporary determination flag is cleared and the large pulsation domain determination flag is set in step S390, and then the present pulsation determination processing is ended.

On the other hand, when the process proceeds to step S400 by determining in step S300 that at least one of the large pulsation domain determination flag and the provisional determination flag is in the on state (S300: no), the value of the counter CNT is incremented by 1 in step S400. Then, in the next step S410, it is determined whether or not the value of the counter CNT is equal to or greater than M, and if the value of the counter CNT is equal to or greater than M (S410: no), the process proceeds to the above-described step S310. When the value of the counter CNT is smaller than M (yes in S410), the current ripple determination process is terminated as it is.

In the engine control device of the present embodiment, as in the third embodiment, the pulsation determination is performed using the instantaneous value of the AFM detection flow rate GA instead of using the minimum flow rate GMIN. However, the instantaneous value of the AFM detected flow rate GA may temporarily become a value indicating a flow rate lower than the original flow rate due to the influence of noise or the like, and thus it may be erroneously determined that the intake pulsation is in a large state.

In contrast, in the present embodiment, when the pulsation rate PR1 reaches a value larger than the pulsation determination value for the first time (yes in S350 and no in S370), only the provisional determination flag is set in a state where the large pulsation region determination flag is cleared (S380). When the pulse rate PR1 becomes a value larger than the pulse determination value again after the period T0 of the intake pulse has elapsed (yes in S350 and yes in S370), a large pulse range determination flag is set (S390). That is, in the present embodiment, when the pulsation rate PR1 continuously exceeds the pulsation determination value in two cycles of the intake pulsation (yes in S370), it is determined that the intake pulsation is in a large state (S390).

The engine control device according to the present embodiment described above can achieve the following effects in addition to the effects (1) to (3) described above.

(5) When the pulsation rate PR1 continuously exceeds the pulsation determination value in two cycles of the intake pulsation, it is determined that the intake pulsation is in a large state. Erroneous determination due to the influence of temporary noise is almost impossible to continue for two cycles of intake pulsation, and therefore erroneous pulsation determination due to the influence of noise can be suppressed.

The above embodiments can be modified and implemented as follows. The embodiments and the following modifications can be combined and implemented within a range not technically contradictory to each other.

In the first and second embodiments, the average flow rate GAVE used for determining the pulsation is obtained by simply averaging the AFM detection flow rates GA in the cycle of the intake pulsation. In the third to fifth embodiments, the average flow rate GAVE1 used for determining pulsation is obtained by a corrected moving average of the AFM detection flow rate GA. The calculation method of these average flow rates GAVE and GAVE1 may be appropriately modified as long as the average value of the intake flow rate in the cycle of the intake pulsation can be calculated or the approximate value of the average value can be calculated. For example, the average flow rate GAVE used for determining pulsation in the first and second embodiments may be obtained by a modified moving average of the AFM detection flow rate GA.

The hysteresis as in the second embodiment may be set to the pulsation determination value used for determining the pulsation in the engine control devices according to the third to fifth embodiments.

The minimum flow rate GMIN may temporarily become a value indicating a flow rate lower than the original flow rate due to the influence of noise. Therefore, even when the pulsation determination is performed using the minimum flow rate GMIN as in the first embodiment, the intake pulsation is determined to be in a large state when the pulsation rate PR continuously exceeds the pulsation determination value in two cycles of the intake pulsation as in the fifth embodiment, and thus erroneous determination due to the influence of noise can be suppressed.

In the forced determination closing process in the fourth embodiment, when at least one of the intake pipe pressure PM being less than the low pressure determination value PM0 and the throttle opening degree TA being less than the low opening degree determination value TA0 is satisfied, the large pulsation region determination value is switched from the established state to the clear state. Not limited to this, the large pulsation region determination value may be switched from the established state to the purge state when both the intake pipe pressure PM is smaller than the low pressure determination value PM0 and the throttle valve opening degree TA is smaller than the low opening degree determination value TA0 are satisfied. Further, of the 2 determinations of step S210 and step S220 in fig. 8, only the determination of step S210 may be omitted, and the forced determination closing process may be performed based only on the throttle opening degree TA, or only the determination of step S220 in fig. 8 may be omitted, and the forced determination closing process may be performed based only on the intake pipe pressure PM.

In the first and second embodiments, the pulse rate PR is determined as a quotient obtained by dividing the difference between the average flow rate GAVE and the minimum flow rate GMIN by the average flow rate GAVE, and the pulsation determination is performed depending on whether or not the pulse rate PR exceeds the pulsation determination value. That is, the pulsation determination is performed with a state in which the relative magnitude of the amplitude of the intake pulsation with respect to the intake air flow rate exceeds the pulsation determination value as a state in which the intake pulsation is large. In contrast, when the magnitude of the intake pulsation is a problem, the pulsation determination may be performed based on whether or not the difference between the average flow rate GAVE and the minimum flow rate GMIN exceeds the pulsation determination value. Similarly, the pulsation determination in the third to fifth embodiments may be performed based on whether or not the difference obtained by subtracting the instantaneous value of the AFM detection flow rate GA from the average flow rate GAVE1 exceeds the pulsation determination value.

In the second calculation process P2 in each of the above embodiments, the intake air amount is calculated by the throttle speed method, but the intake air amount may be calculated by the speed density method based on the detected value of the intake pipe pressure PM. In this case, the intake air amount is also calculated in the second calculation process P2 without using the output of the airflow meter 13. Therefore, if the calculated value of the intake air amount in the second calculation process P2 is used as the calculated value of the intake air amount used for determining the instruction injection amount Q of the injector 18 when the intake pulsation is in a large state, it is possible to suppress a decrease in the control accuracy of the fuel injection amount due to an increase in the intake pulsation.

In each of the above embodiments, the calculated value of the intake air amount selected by the calculation method switching process P4 from the first and second calculated intake air amounts MC1 and MC2 is used for determining the instructed injection amount Q of the injector 18. The calculation value of the intake air amount selected by the calculation method switching process P4 may be used to determine the operation amount of an actuator other than the injector 18 provided in the engine 10. As the operation amount of the actuator, an instruction value of the throttle opening TA with respect to the throttle motor 15 and an instruction value of the ignition timing of the air-fuel mixture with respect to the ignition device 21 can be considered. In addition, the operation amount of the actuator can be set to an instruction value for the valve timing of the variable valve timing mechanism 19A, an instruction value for the recirculation amount of exhaust gas of the EGR device, an instruction value for the emission amount of fuel vapor of the vapor purge mechanism, and the like.

The electronic control unit 26 is not limited to being provided with the arithmetic processing circuit 27 and the memory 28 and executing various software processes. For example, a dedicated hardware circuit such as an ASIC may be provided for performing hardware processing on at least a part of the software processing in the above embodiment. That is, the electronic control unit may have any one of the following configurations (a) to (c). (a) The program storage device (including a non-transitory computer-readable storage medium) includes a processing device that executes all of the above-described processes in accordance with a program, and a program storage device (such as a ROM) that stores the program. (b) The apparatus includes a processing device and a program storage device for executing a part of the above-described processing in accordance with a program, and a dedicated hardware circuit for executing the remaining processing. (c) The apparatus includes a dedicated hardware circuit for executing all of the above-described processing. Here, the software executing apparatus and the dedicated hardware circuit provided with the processing apparatus and the program storage apparatus may be plural ones.