JP2017072076A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further properly determine a failure of an in-cylinder fuel injection valve, in an internal combustion engine having the in-cylinder fuel injection valve, a port fuel injection valve and an EGR device.SOLUTION: When an operation motion point (suction air amount Qa, rotation number Ne) of an internal combustion engine enters a determination execution region, and a determination execution condition is established, an EGR is stopped while the determination execution condition is established, a port fuel injection valve is stopped, fuel is injected from an in-cylinder fuel injection valve, and a failure of the in-cylinder fuel injection valve is determined. A hysteresis region for maintaining the establishment of the determination execution condition is set in a boundary of the determination execution region, and the hysteresis region is set wide as an EGR rate at the establishment of the determination execution condition is high. By this constitution, at the moment that the determination execution condition is established, and the EGR is stopped, the operation point is deviated from the determination execution region and the hysteresis region, and the generation of hunting at which the establishment and the non-establishment of the determination execution condition are repeated can be suppressed.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine including an in-cylinder fuel injection valve, a port fuel injection valve, and an EGR device.

  Conventionally, in a control device for an engine (internal combustion engine) including a direct injection injector, a port injector, and an EGR device, when a detection execution condition is satisfied, the recirculation of exhaust gas is stopped and the fuel injection from the port injector is stopped, There has been proposed a method for determining a failure of a direct injection injector by performing fuel injection from the direct injection injector (see, for example, Patent Document 1). In this apparatus, when the engine operation operating point (the number of revolutions, the air amount) enters a predetermined detection region, it is determined that the detection execution condition is satisfied, and a failure determination of the direct injection injector is performed. The detection region is a region where the engine operating state is stable when the engine speed is between Y1 and Y2 and when the amount of air taken into the engine is between Z1 and Z2.

Japanese Patent Laid-Open No. 2015-101983

  By the way, when the detection execution condition is satisfied in a state where the EGR gas is recirculated by the EGR device, the recirculation of the EGR gas is stopped, and the amount of air sucked into the cylinder greatly changes. At this time, the operating point of the engine may be outside the detection region, and the detection execution condition may not be satisfied. As described above, the direct injection injector failure determination is performed in a state where the fuel injection of the port injector is stopped. Therefore, if the detection execution condition is not satisfied immediately after the detection execution condition is satisfied, the fuel injection ratio of the port injector and the direct injection injector changes. Hunting occurs. The occurrence of such hunting causes deterioration of fuel consumption and emission, and causes misjudgment when making a direct-injector failure judgment.

  The control device for an internal combustion engine according to the present invention enables a failure determination of an in-cylinder fuel injection valve to be performed more appropriately in an internal combustion engine including an in-cylinder fuel injection valve, a port fuel injection valve, and an EGR device. The main purpose.

  The control device for an internal combustion engine of the present invention employs the following means in order to achieve the main object described above.

The control device for an internal combustion engine of the present invention comprises:
An internal combustion engine comprising: an in-cylinder fuel injection valve that directly injects fuel into a cylinder; a port fuel injection valve that injects fuel into an intake passage; and an EGR device that recirculates EGR gas from an exhaust passage to the intake passage. A control device of
An execution condition is established based on the operation operating point of the internal combustion engine being within a predetermined operation range, and while the execution condition is established, the recirculation of EGR gas is stopped and the port fuel injection valve Failure determination means for stopping the fuel injection, performing fuel injection from the in-cylinder fuel injection valve, and performing a failure determination of the in-cylinder fuel injection valve;
Hysteresis region setting means for setting a hysteresis region that maintains the execution condition at the boundary of the operation region;
With
The gist of the hysteresis region setting means is to set the hysteresis region so that the hysteresis region becomes wider as the EGR rate when the execution condition is satisfied is higher.

  In the control device for an internal combustion engine according to the present invention, the execution condition is established based on the operation point of the internal combustion engine being within a predetermined operation region, and the EGR gas recirculation is stopped while the execution condition is established. At the same time, the fuel injection from the port fuel injection valve is stopped, the fuel injection is performed from the in-cylinder fuel injection valve, and the failure determination of the in-cylinder fuel injection valve is executed. In addition, a hysteresis region that maintains the execution condition is set at the boundary of the operation region, and the hysteresis region becomes wider as the EGR rate when the execution condition is satisfied is higher. Thereby, even if the execution condition is satisfied in a state where the EGR gas is recirculated and the recirculation of the EGR gas is stopped, it is possible to suppress the occurrence of hunting in which the execution condition is not satisfied immediately thereafter. As a result, the failure determination of the in-cylinder fuel injection valve can be performed more appropriately. The “driving operation point” can be an operating point determined based on the rotational speed and load (intake air amount) of the internal combustion engine.

1 is a configuration diagram showing an outline of the configuration of an internal combustion engine 20 and its control device 24 as one embodiment of the present invention. 4 is a flowchart illustrating an example of an operation control routine executed by a CPU 24a of the control device 24. It is a flowchart which shows an example of the condition success / failure determination process performed by CPU24a of the control apparatus 24. It is explanatory drawing explaining the determination execution area | region. It is explanatory drawing which shows the relationship between the EGR rate at the time of determination execution condition satisfaction, and a hysteresis area | region.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a block diagram showing an outline of the configuration of an internal combustion engine 20 and its control device 24 as one embodiment of the present invention. As shown in FIG. 1, the internal combustion engine 20 of the embodiment has an in-cylinder fuel injection valve 25 that directly injects hydrocarbon-based fuel such as gasoline and light oil into a cylinder, and a port for injecting fuel into an intake port. And a fuel injection valve 26. The internal combustion engine 20 is equipped with the in-cylinder fuel injection valve 25 and the port fuel injection valve 26, so that the operation mode is any one of the port injection operation mode, the in-cylinder injection operation mode, and the common injection operation mode. Driving is possible. These operation modes are switched based on the current operation state of the internal combustion engine 20, the operation state required for the internal combustion engine 20, and the like.

  In the port injection operation mode, air cleaned by the air cleaner 22 is sucked through the throttle valve 24 and gasoline is injected from the port fuel injection valve 26 to mix the sucked air and fuel. Then, the air-fuel mixture is sucked into the combustion chamber via the intake valve 28 and explosively burned by an electric spark from the spark plug 30, and the reciprocating motion of the piston 32 pushed down by the energy is converted into the rotational motion of the crankshaft 26. .

  Similarly, in the in-cylinder injection operation mode, air is sucked into the combustion chamber, fuel is injected from the in-cylinder fuel injection valve 25 during the intake stroke or the compression stroke, and explosive combustion is performed by an electric spark from the spark plug 30. Thus, the rotational movement of the crankshaft 26 is obtained.

  In the common injection operation mode, when air is sucked into the combustion chamber, fuel is injected from the port fuel injection valve 26 and fuel is injected from the in-cylinder fuel injection valve 25 in the intake stroke or compression stroke, and this is exploded and burned. A rotational movement of the crankshaft 26 is obtained.

  Exhaust gas from the internal combustion engine 20 is supplied to outside air via a purification device 34 having a purification catalyst (three-way catalyst) 34a for purifying harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). And is supplied to the intake side via an EGR (Exhaust Gas Recirculation) system 60.

  The EGR system 60 includes an EGR pipe 62 that is connected to the rear stage of the purification device 34 and supplies exhaust gas to a surge tank on the intake side, and an EGR valve 64 that is disposed in the EGR pipe 62 and is driven by a stepping motor 63. . The EGR system 60 adjusts the supply amount of exhaust gas as non-combustion gas and supplies it to the intake side by adjusting the opening of the EGR valve 64. The internal combustion engine 20 can be operated by sucking a mixture of air, exhaust and gasoline into the combustion chamber. Hereinafter, supplying the exhaust gas of the internal combustion engine 20 to the intake side is referred to as EGR.

  The control device 24 is configured as a microprocessor centered on the CPU 24a. In addition to the CPU 24a, the control device 24 includes a ROM 24b for storing processing programs, a RAM 24c for temporarily storing data, an input / output port and a communication port (not shown). Prepare.

  Signals from various sensors that detect the state of the internal combustion engine 20 are input to the control device 24 via an input port. Specifically, the control device 24 includes the crank position θcr from the crank position sensor 40 that detects the rotational position of the crankshaft 26 and the cooling water temperature Tw from the water temperature sensor 42 that detects the temperature of the cooling water in the internal combustion engine 20. Entered. Further, the control device 24 includes an in-cylinder pressure Pin from a pressure sensor (not shown) installed in the combustion chamber, an intake cam shaft that opens and closes the intake valve 28 that performs intake and exhaust to the combustion chamber, and an exhaust cam that opens and closes the exhaust valve 29. A cam angle or the like is input from a cam position sensor 44 that detects the rotational position of the shaft. Further, the control device 24 includes a throttle opening TH from a throttle valve position sensor 46 that detects the position of the throttle valve 24 and an intake air amount from an air flow meter 48 that is attached to the intake pipe and detects the mass flow rate of the intake air. Qa or the like is input. Further, the control device 24 detects the intake air temperature Ta from the temperature sensor 49 attached to the intake pipe, the intake pipe pressure from the pressure sensor 58 that detects the pressure in the intake pipe, and the temperature of the purification catalyst 34a of the purification device 34. The catalyst temperature θc and the like are input from the temperature sensor 34b. The control device 24 receives an air-fuel ratio AF from an air-fuel ratio sensor 35a attached to the exhaust system, an oxygen signal O2 from an oxygen sensor 35b also attached to the exhaust system, and the like. Further, the EGR valve opening degree EV from the EGR valve opening degree sensor 65 that detects the opening degree of the EGR valve 64 is input to the control device 24.

  Further, the control device 24 outputs various control signals for driving the internal combustion engine 20 via the output port. Specifically, from the control device 24, a drive signal to the cylinder fuel injection valve 25, a drive signal to the port fuel injection valve 26, and a drive signal to the throttle motor 36 that adjusts the opening of the throttle valve 24. Is output. Further, the control device 24 sends a control signal to the ignition coil 38 integrated with the igniter, a control signal to the variable valve timing mechanism 50 that can change the opening / closing timing VT of the intake valve 28, and the opening degree of the EGR valve 64. A drive signal to the stepping motor 63 to be adjusted is output.

  The control device 24 calculates the rotational speed of the crankshaft 26, that is, the rotational speed Ne of the internal combustion engine 20 based on the crank position θcr from the crank position sensor 40. Further, the control device 24 calculates a knock intensity Kr indicating a knocking occurrence level based on the magnitude and waveform of the knock signal Ks from the knock sensor 59. Further, the control device 24 determines the EGR amount and the intake of the internal combustion engine 20 based on the intake air amount Qa from the air flow meter 48, the EGR valve opening EV from the EGR valve opening sensor 65, and the rotational speed Ne of the internal combustion engine 20. An EGR rate is calculated as a ratio of the EGR amount to the sum of the air amount Qa.

  The control device 24 determines whether or not misfire has occurred in the internal combustion engine 20 after operating the internal combustion engine 20 in the in-cylinder injection operation mode when a predetermined execution condition is satisfied. If the control device 24 determines that no misfire has occurred in the internal combustion engine 20, it determines that no failure has occurred in the in-cylinder fuel injection valve 25, and determines that a misfire has occurred in the internal combustion engine 20. Then, it is determined that a failure has occurred in the in-cylinder combustion injection valve 25. Note that the misfire determination is performed based on, for example, a signal detected by detecting the rotation of the crankshaft 26 between the cylinders, based on the in-cylinder pressure Pin, or detecting ions generated during combustion. You can go. Further, the control device 24 can perform failure determination of the port fuel injection valve 26 by a similar method.

  Further, when the failure determination of the in-cylinder fuel injection valve 25 is performed, the control device 24 closes the EGR valve 64 and stops the EGR. As described above, the failure determination of the cylinder fuel injection valve 25 is performed in a state where the fuel injection of the port fuel injection valve 26 is stopped. If EGR is performed in this state, the cooling effect by the fuel injection cannot be obtained, so the tip of the port fuel injection valve 26 becomes high temperature due to the heat of the exhaust, and deposits are likely to accumulate. In this embodiment, when the failure determination of the in-cylinder fuel injection valve 25 is performed, the EGR is stopped. Therefore, the tip of the port fuel injection valve 26 is prevented from becoming high temperature, and deposits are prevented from being accumulated. it can.

  Next, the operation control of the internal combustion engine 20 when determining the failure of the cylinder fuel injection valve 25 will be described. FIG. 2 is a flowchart illustrating an example of an operation control routine executed by the CPU 24 a of the control device 24. This process is repeatedly executed every predetermined time (for example, every several msec).

  When the operation control routine is executed, the CPU 24a of the control device 24 first determines whether or not a determination execution condition for determining a failure of the in-cylinder fuel injection valve 25 is satisfied (step S100). This process is performed by executing a condition success / failure determination process of FIG. 3 described later. If the CPU 24a determines that the condition satisfaction flag is off and the determination execution condition is not satisfied ("NO" in step S110), the CPU 24a executes normal operation control (step S120) and ends the operation control routine. The process of step S120 selects any one of the port injection operation mode, the in-cylinder injection operation mode, and the common injection operation mode based on the operation state of the internal combustion engine 20, and the in-cylinder fuel injection valve corresponding to the selected operation mode. 25 and the fuel injection valve 26 for the port are controlled. Further, the EGR valve 64 is driven and controlled so that EGR is performed based on the operating state of the internal combustion engine 20.

  On the other hand, if the CPU 24a determines that the condition satisfaction flag is on and the determination execution condition is satisfied ("YES" in step S110), the CPU 24a closes the EGR valve 64 and stops EGR (step S130). Subsequently, the CPU 24a stops fuel injection from the port fuel injection valve 26 (step S140) and performs fuel injection from the in-cylinder fuel injection valve 25 (step S150). Then, the CPU 24a determines whether or not the failure determination of the in-cylinder fuel injection valve 25 has been completed (step S160). Note that the failure determination of the in-cylinder fuel injection valve 25 has been described above. If it is determined that the failure determination of the in-cylinder fuel injection valve 25 has not been completed, the operation control routine is temporarily ended while maintaining the condition satisfaction flag state. On the other hand, if it is determined that the failure determination of the in-cylinder fuel injection valve 25 has been completed, the condition satisfaction flag is changed from on to off (step S170), and the operation control routine ends.

  Next, the condition success / failure determination process of FIG. 3 will be described. In the condition success / failure determination process, the CPU 24a first determines whether or not a precondition for performing a failure determination of the in-cylinder fuel injection valve 25 is satisfied (step S200). The precondition may be a condition that is satisfied when the failure determination timing of the in-cylinder fuel injection valve 25 has arrived, for example, when the failure determination of the in-cylinder fuel injection valve 25 is performed at a predetermined frequency. For example, when the failure determination of the in-cylinder fuel injection valve 25 is performed only once after the system is started until the system is stopped, the failure determination of the in-cylinder fuel injection valve 25 is still completed after the system is started. The precondition is satisfied when not. When determining that the precondition is not satisfied, the CPU 24a ends the condition success / failure determination process as it is.

  On the other hand, when the CPU 24a determines that the precondition is satisfied, the CPU 24a inputs the EGR rate, the rotation speed Ne, and the intake air amount Qa (step S210), and determines whether or not the condition satisfaction flag is off (step S210). S220). If it is determined that the condition satisfaction flag is off, whether or not the input rotation speed Ne is equal to or higher than the lower limit rotation speed NL and equal to or lower than the upper limit rotation speed NH, the input intake air intake amount Qa is equal to or higher than the lower limit air amount QL and upper limit It is determined whether or not the air amount is equal to or less than QH (step S230). The determination in step S230 is to determine whether or not the operation point (intake air amount Qa, rotation speed Ne) of the internal combustion engine 20 is within the determination execution region as shown in FIG. Note that the determination execution region defines an operation region in which it can be determined that the operation state of the internal combustion engine 20 is stable. If any of the determinations in step S230 is negative (the driving operation point is outside the determination execution region), the CPU 24a ends the condition success / failure determination process without turning on the condition satisfaction flag. On the other hand, when all of the above-described determinations are positive determinations (the driving operation point is in the determination execution region), it is determined that the determination execution condition is satisfied, and the condition satisfaction flag is turned on (step S240). ). Accordingly, the failure determination of the in-cylinder fuel injection valve 25 is performed only when the operation state of the internal combustion engine 20 is stable. Therefore, the in-cylinder fuel injection valve 25 is used when the internal combustion engine 20 is in an unstable operation state. It is possible to prevent erroneous determination by preventing failure determination of the fuel injection valve 25. Note that the determination execution condition may include not only a condition based on the operation point of the internal combustion engine 20 but also other conditions such as a condition based on the cooling water temperature Ta. When the condition establishment flag is turned on, the CPU 24a sets the hysteresis amounts Nhis and Qhis (hysteresis region) based on the EGR rate input in step S210 (step S250), and ends the condition success / failure determination process. Here, the hysteresis region is a region set at the boundary of the above-described determination execution region in order to maintain the state after the determination execution condition is once established. Details of the hysteresis amounts Nhis and Qhis will be described later.

  When the condition satisfaction flag is turned on in step S240, the CPU 24a determines that the condition satisfaction flag is turned on in step S220 when the condition success / failure determination process is executed in the next round. Then, the CPU 24a determines whether or not the rotational speed Ne is smaller than the rotational speed obtained by subtracting the hysteresis amount Nhis from the lower limit rotational speed NL (NL-Nhis), and the rotational speed Ne is obtained by adding the hysteresis amount Nhis to the upper rotational speed NH. Whether the intake air amount Qa is smaller than the air amount obtained by subtracting the hysteresis amount Qhis from the lower limit air amount QL (QL-Qhis), or the intake air amount Qa is the upper limit air amount QH It is determined whether or not it is larger than the air amount (QH + Qhis) obtained by adding the hysteresis amount Qhis (step S260). The determination in step S260 is to determine whether or not the operating point of the internal combustion engine 20 has deviated from the determination execution region and the hysteresis region around it. When all of the determinations in step 260 are negative determinations (the driving operation point is in the determination execution region or the hysteresis region), the CPU 24a ends the condition success / failure determination process with the condition satisfaction flag turned on. . On the other hand, if any of the above-described determinations is affirmative (the driving operation point is outside the determination execution region and the hysteresis region), the condition satisfaction flag is turned off from on (step S270), and the condition success / failure determination processing is performed. Exit. Thus, since the CPU 24a determines that the condition satisfaction flag is OFF in step S110, even if the failure determination is in the middle of execution, the CPU 24a interrupts this and executes the operation control in step S120. That is, the CPU 24a selects an operation mode (port injection operation mode, in-cylinder injection operation mode, shared injection operation mode) according to the operation state of the internal combustion engine 20, and the in-cylinder fuel injection valve corresponding to the selected operation mode. 25 and the fuel injection control of the port fuel injection valve 26 are resumed. Further, the EGR valve 64 is driven and controlled so that the EGR is resumed according to the operating state of the internal combustion engine.

  Here, the hysteresis amounts Nhis and Qhis set in step S250 will be described. FIG. 5 is an explanatory diagram showing the relationship between the EGR rate and the hysteresis region when the determination execution condition is satisfied. As shown in the figure, the hysteresis amounts Nhis and Qhis are set to increase as the EGR rate when the determination execution condition is satisfied is higher. The hysteresis amounts Nhis and Qhis may be changed continuously with respect to the change in the EGR rate, or may be changed stepwise.

  As described above, the failure determination of the in-cylinder fuel injection valve 25 is performed in a state where the supply of exhaust gas (EGR) to the intake system is stopped. For this reason, if the determination execution condition for failure determination is satisfied while EGR is being performed, the intake air amount Qa greatly changes at the moment when EGR is stopped. The change in the intake air amount Qa becomes larger as the amount of exhaust gas supplied to the intake system when the determination execution condition is satisfied (the EGR rate is higher). In this case, even if the operation operating point (intake air amount Qa, rotation speed Ne) of the internal combustion engine 20 once enters the determination execution region and the determination execution condition is satisfied, the operation operation point is determined at the moment when EGR is stopped. There are cases where hunting occurs where the execution region and the hysteresis region are deviated and the determination execution condition is repeatedly satisfied and not satisfied. When the determination execution condition is satisfied or not satisfied, hunting may occur between a state where combustion injection is performed only from the cylinder fuel injection valve 25 and a state where combustion injection is performed also from the port fuel injection valve 26. In this case, inconveniences such as deterioration in fuel consumption, instability of the operating state of the internal combustion engine 20, and deterioration in determination accuracy of failure determination occur. On the other hand, in the present embodiment, the higher the EGR rate when the determination execution condition is satisfied, the larger the hysteresis amounts Nhis and Qhis (wider the hysteresis region) are set. Hunting can be suppressed, and the above-described inconvenience can be suppressed.

  According to the control device 24 of the internal combustion engine of the present embodiment described above, the determination execution is performed when the operation operating point (intake air amount Qa, rotation speed Ne) of the internal combustion engine 20 enters the determination execution region and the determination execution condition is satisfied. While the condition is satisfied, EGR is stopped, the port fuel injection valve 26 is stopped, fuel is injected from the in-cylinder fuel injection valve 25, and a failure determination of the in-cylinder fuel injection valve 25 is performed. In addition, a hysteresis region for maintaining the determination execution condition is established at the boundary of the determination execution region, and the hysteresis region becomes wider as the EGR rate when the determination execution condition is satisfied is higher. As a result, at the moment when the determination execution condition is satisfied and EGR is stopped, the operating point of the internal combustion engine 20 deviates from the determination execution region and the hysteresis region, and hunting occurs in which the determination execution condition is repeatedly satisfied and not satisfied. Can be effectively suppressed. As a result, it is possible to prevent inconveniences such as deterioration of fuel consumption due to the occurrence of hunting, instability of the operating state of the internal combustion engine 20, and deterioration of failure determination accuracy.

  In the embodiment, both the hysteresis amount Qhis of the intake air amount Qa and the hysteresis amount Nhis of the rotational speed Ne are changed based on the EGR rate when the determination execution condition is satisfied. However, only the hysteresis amount Qhis is changed and the hysteresis is changed. The amount Nhis may be constant regardless of the EGR rate.

    The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the in-cylinder fuel injection valve 25 corresponds to the “in-cylinder fuel injection valve”, the port fuel injection valve 26 corresponds to the “port fuel injection valve”, and the EGR system 60 corresponds to the “EGR device”. It corresponds to. Further, the CPU 24a of the control device 24 that executes the processes of S100, S110, and S130 to S170 of the operation control routine of FIG. 2 corresponds to “failure determination means”, and executes the process of S250 of the condition satisfaction determination process of FIG. The CPU 24a of the control device 24 corresponds to “hysteresis area setting means”.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention is applicable to the vehicle manufacturing industry.

  20 Internal combustion engine, 22 Air cleaner, 24 Throttle valve, 24a CPU, 24b ROM, 24c RAM, 25 In-cylinder fuel injection valve, 26 port fuel injection valve, 28 Intake valve, 29 Exhaust valve, 30 Spark plug, 32 Piston, 34 purification device, 34a purification catalyst, 34b temperature sensor, 35a air-fuel ratio sensor, 35b oxygen sensor, 36 throttle motor, 38 ignition coil, 40 crank position sensor, 42 water temperature sensor, 44 cam position sensor, 46 throttle valve position sensor, 48 Air flow meter, 49 Temperature sensor, 50 Variable valve timing mechanism, 58 Pressure sensor, 59 Knock sensor, 60 EGR system, 62 EGR pipe, 63 Stepping motor, 64 EG R valve, 65 EGR valve opening sensor.

Claims (1)

An internal combustion engine comprising: an in-cylinder fuel injection valve that directly injects fuel into a cylinder; a port fuel injection valve that injects fuel into an intake passage; and an EGR device that recirculates EGR gas from an exhaust passage to the intake passage. A control device of
An execution condition is established based on the operation operating point of the internal combustion engine being within a predetermined operation range, and while the execution condition is established, the recirculation of EGR gas is stopped and the port fuel injection valve Failure determination means for stopping the fuel injection, performing fuel injection from the in-cylinder fuel injection valve, and performing a failure determination of the in-cylinder fuel injection valve;
Hysteresis region setting means for setting a hysteresis region that maintains the execution condition at the boundary of the operation region;
With
The control apparatus for an internal combustion engine, wherein the hysteresis region setting means sets the hysteresis region so that the hysteresis region becomes wider as the EGR rate when the execution condition is satisfied is higher.

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