JP2005139962A - Control device for an internal combustion engine detecting a failure of a cylinder deactivation mechanism - Google Patents

Abstract

A failure of cylinder deactivation control is detected by a simple method.
A control device for an internal combustion engine having a mechanism for performing cylinder deactivation control for deactivating a portion of a plurality of cylinders is provided in an intake system of the internal combustion engine, and an intake air amount to the internal combustion engine , A means for detecting a deceleration state of a vehicle on which the internal combustion engine is mounted, and a means for outputting a command for starting cylinder deactivation control to the internal combustion engine when the deceleration state is detected. The control device compares the detected intake air amount with a threshold set based on the rotational speed of the internal combustion engine after a command for starting cylinder deactivation control is output to the internal combustion engine. When the detected intake air amount is equal to or greater than the threshold value, it is determined that some failure has occurred in the cylinder deactivation control.
[Selection] Figure 4

Description

  The present invention relates to an apparatus for detecting a failure in cylinder deactivation control with respect to an internal combustion engine that has a plurality of cylinders and includes a mechanism for performing cylinder deactivation control that deactivates some of the plurality of cylinders.

  There is an internal combustion engine that includes a plurality of cylinders and includes a cylinder deactivation mechanism that deactivates some of the plurality of cylinders. In such an internal combustion engine, an all-cylinder operation in which all of the plurality of cylinders are operated and a cylinder deactivation operation in which the operations of some of the cylinders are stopped are switched according to the operation state. If any failure occurs in the operation of the cylinder deactivation mechanism, such switching is not appropriately performed, and thus the air-fuel ratio may deteriorate or a desired engine output may not be obtained.

Patent Document 1 below describes a technique for detecting such a switching failure between all-cylinder operation and cylinder deactivation operation. According to this method, the intake pipe pressure during all-cylinder operation estimated based on the detected engine speed and the throttle valve opening, and the actual intake pipe pressure detected by a sensor provided in the intake pipe, To determine the failure of the switching.
JP-A-6-146937

  According to the conventional method, a plurality of sensors are required to detect a failure in switching between all-cylinder operation and cylinder deactivation operation. The calculation using the detection values of the plurality of sensors may increase the load on the computer that controls the vehicle.

  Therefore, there is a need for a device that can detect any failure in cylinder deactivation control with good accuracy by a simple calculation without increasing the number of sensors.

  According to one aspect of the present invention, a control device for an internal combustion engine including a mechanism for performing cylinder deactivation control for deactivating a part of a plurality of cylinders is provided in an intake system of the internal combustion engine, and the internal combustion engine Means for detecting the amount of intake air to the vehicle, means for detecting the deceleration state of the vehicle on which the internal combustion engine is mounted, and outputs a command for starting cylinder deactivation control to the internal combustion engine when the deceleration state is detected. Means. Further, the control device compares the detected intake air amount with a threshold set based on the rotational speed of the internal combustion engine after a command for starting cylinder deactivation control is output to the internal combustion engine. And a failure determination unit that determines that a failure has occurred in cylinder deactivation control when the detected intake air amount is equal to or greater than the threshold value.

  According to the present invention, since it is possible to determine a failure in cylinder deactivation control based on the intake air amount, it is possible to detect a failure with a simple calculation while suppressing the number of sensors necessary for the failure determination. During deceleration, the difference in the change rate of the intake air amount between the all-cylinder operation and the cylinder deactivation operation is large. Therefore, it is possible to detect a cylinder deactivation control failure with good accuracy.

  In one embodiment of the present invention, the control device determines whether or not the rate of change of the detected intake air amount is stable. When it is determined that the rate of change is in a stable state, it is determined that a failure has occurred in the cylinder deactivation control when the detected intake air amount is equal to or greater than the threshold value.

  When the change rate of the intake air amount is stabilized, the difference in the intake air amount between the all cylinder operation and the cylinder deactivation operation is stabilized. Therefore, according to the present invention, a failure in cylinder deactivation control can be detected more stably.

  In one embodiment of the present invention, when the fuel supply to the internal combustion engine is stopped, the threshold value is corrected according to the target intake air amount.

  Normally, even when the deceleration is the same, the target intake air amount differs between when the fuel supply is stopped and when the fuel supply is not stopped, and thus the air actually sucked into the internal combustion engine. The amount is different. According to the present invention, even when the fuel supply is stopped, the threshold value is corrected according to the target intake air amount, so that it is possible to more reliably determine the failure of cylinder deactivation control.

  According to one embodiment of the present invention, the threshold value is corrected according to the detected intake air temperature. The amount of air taken into the internal combustion engine may change depending on the intake air temperature. According to the present invention, since the threshold value is corrected according to the intake air temperature, it is possible to determine the failure of the cylinder deactivation control while suppressing the influence of the intake air temperature.

  According to another aspect of the present invention, the comparison means further includes the detected intake air amount and the rotation of the internal combustion engine immediately after a command for starting cylinder deactivation control is output to the internal combustion engine. The first comparison means for comparing the first threshold value set based on the number, and when the change rate of the detected intake air amount is stable, the detected intake air amount and the internal combustion engine Second comparing means for comparing with a second threshold value set based on the rotational speed. The failure determination unit further includes a first failure that determines that some failure has occurred in the cylinder deactivation control if the detected intake air amount is equal to or greater than the first threshold value in the comparison by the first comparison unit. In the comparison by the determination means and the second comparison means, a second failure determination means for determining that some failure has occurred in the cylinder deactivation control if the detected intake air amount is not less than the second threshold value. Prepare.

  If the cylinder deactivation control operates normally, immediately after the cylinder deactivation control is started, the intake air amount decreases at a large change rate compared to the all-cylinder operation. Therefore, according to this invention, it can be investigated at an early stage whether the cylinder deactivation control has started normally. Further, when the rate of change of the intake air amount is stabilized, the difference in the intake air amount between the all cylinder operation and the cylinder deactivation operation is stabilized. Therefore, according to the present invention, a failure in cylinder deactivation control can be detected more stably.

  In one embodiment of the present invention, the second threshold value is set smaller than the first threshold value. By setting in this way, the first threshold value is set so as to be close to the characteristics of the intake air amount at the time of all cylinder operation, and the second threshold value is the intake air amount at the time of cylinder deactivation operation. It is set to be close to the characteristics. By comparing with the first threshold value, the failure of cylinder deactivation control can be determined earlier. By comparing with the second threshold value, the cylinder deactivation control can be determined more reliably.

  Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of an internal combustion engine and its control device according to an embodiment of the present invention.

  An electronic control unit (hereinafter referred to as “ECU”) 1 includes an input interface 1a that receives data sent from each part of the vehicle, a CPU 1b that executes calculations for controlling each part of the vehicle, and a read-only memory (ROM) ) And a random access memory (RAM) 1c and an output interface 1d for sending control signals to various parts of the vehicle. The ROM of the memory 1c stores a program for controlling each part of the vehicle and various data. A program for realizing failure determination of cylinder deactivation control according to the present invention, and data and tables used when executing the program are stored in this ROM. The ROM may be a rewritable ROM such as an EPROM. The RAM is provided with a work area for calculation by the CPU 1b. Data sent from each part of the vehicle and control signals sent to each part of the vehicle are temporarily stored in the RAM.

  An internal combustion engine (hereinafter referred to as “engine”) 2 includes a plurality of cylinders. As an example, a V-type 6-cylinder engine is shown. A first cylinder group (hereinafter referred to as a first bank) 21 includes three cylinders (# 1 to # 3), and a second cylinder group ( Hereinafter, the second bank 22 is also provided with three cylinders (# 4 to # 6).

  The engine 2 is provided with a cylinder deactivation mechanism 23. The cylinder deactivation mechanism 23 is hydraulically driven using the lubricating oil of the engine 2. The cylinder deactivation mechanism 23 is an all-cylinder operation in which all six cylinders in the first bank 21 and the second bank 22 are operated, and a cylinder deactivation operation in which fuel supply to the three cylinders in the first bank 21 is stopped. The engine 2 is switched between. When performing the cylinder deactivation operation, the cylinder deactivation mechanism 23 maintains the intake valves and exhaust valves of the three cylinders of the first bank 21 in the closed state.

  The intake pipe 3 branches downstream of the throttle valve 4 into a passage 3a leading to the first bank and a passage 3b leading to the second bank. Further, the passage 3a is branched into passages reaching the cylinders # 1 to # 3 of the first bank, and the passage 3b is branched into passages reaching the cylinders # 4 to # 6 of the second bank.

  The fuel injection valve 5 is provided for each cylinder in a passage leading to each cylinder. In the figure, only one fuel injection valve 5 is shown for simplicity. The fuel injection valve 5 receives supply of fuel from a fuel tank (not shown) and injects the fuel. The valve opening time of the fuel injection valve 5 is controlled by a control signal from the ECU 1.

  A throttle valve 4 is disposed upstream of the intake pipe 3. A throttle valve opening sensor (TH) 6 connected to the throttle valve 4 sends an electric signal corresponding to the opening of the throttle valve 4 to the ECU 1. The opening degree of the throttle valve 4 is controlled by a control signal from the ECU 1. The air taken in through the throttle valve 4 passes through the intake pipe 3 and is mixed with the fuel injected from the fuel injection valve 5 and supplied to each cylinder.

  An air flow meter (AFM) 7 is provided upstream of the throttle valve 4. The air flow meter 7 detects the amount of air passing through the throttle valve 4 and sends it to the ECU 1. The air flow meter 7 can be a vane air flow meter, a Karman vortex air flow meter, a hot wire air flow meter, or the like.

  An intake pipe pressure (Pb) sensor 8 and an intake temperature (Ta) sensor 9 are provided on the downstream side of the throttle valve 4 of the intake pipe 3, and detect the intake pipe pressure Pb and the intake temperature TA, respectively, and send them to the ECU 1. .

  The engine water temperature (TW) sensor 11 is attached to a cylinder peripheral wall (not shown) filled with cooling water in the cylinder block of the engine 2, detects the temperature TW of engine cooling water, and sends it to the ECU 1.

  The engine 2 is provided with a crank angle (CRK) sensor 12. The crank angle sensor 12 outputs a CRK signal and a TDC signal, which are pulse signals, to the ECU 1 as the crankshaft rotates. The CRK signal is a pulse signal output at a predetermined crank angle (for example, 30 degrees). The ECU 1 calculates the rotational speed NE of the engine 2 according to the CRK signal. Further, a TDC signal is output at a crank angle related to the TDC position of the piston and sent to the ECU 1.

  An exhaust pipe 15a is connected to the first bank, and gas discharged from the cylinders of the first bank flows into the exhaust pipe 15a. An exhaust pipe 15b is connected to the second bank, and gas discharged from the cylinders of the second bank flows into the exhaust pipe 15b.

  Wide area air-fuel ratio sensors (LAF) sensors 16a and 16b are provided in the exhaust pipes 15a and 15b, respectively. The LAF sensors 16a and 16b linearly detect the oxygen concentration in the exhaust gas in a wide range of air-fuel ratios ranging from lean to rich. The detected oxygen concentration is sent to the ECU 1.

  Downstream of the LAF sensors 16a and 16b, catalyst devices 17a and 17b for purifying harmful components in the exhaust gas are provided, respectively. O2 (exhaust gas) sensors 18a and 18b are provided downstream of the catalyst devices 17a and 17b. The O2 sensors 17a and 17b are binary exhaust gas concentration sensors. The O2 sensors 18a and 18b output a high level signal when the air-fuel ratio is richer than the stoichiometric air-fuel ratio, and output a low-level signal when the air-fuel ratio is leaner than the stoichiometric air-fuel ratio. The output electrical signal is sent to the ECU 1.

  The exhaust pipes 15a and 15b join the exhaust passage 15 downstream of the O2 sensors 18a and 18b. Additional catalyst devices, LAF sensors, and O2 sensors may be provided in the exhaust passage 15.

  The vehicle speed (VP) sensor 19 detects the speed VP of the vehicle on which the engine 2 is mounted and sends it to the ECU 1.

  Input signals from various sensors are passed to the input interface 1a of the ECU 1. The input interface 1a converts an analog signal value into a digital signal value. The CPU 1b processes the converted digital signal, performs an operation according to a program stored in the memory 1c, and generates a control signal to be sent to the actuator of each part of the vehicle. This control signal is sent to the output interface 1d, and the output interface 1d sends a control signal to an actuator such as the fuel injection valve 5.

FIG. 2 schematically shows a hydraulic circuit for driving the cylinder deactivation mechanism 23. The intake-side hydraulic control valve 41 and the exhaust-side hydraulic control valve 42 are opened and closed in accordance with a control signal from the ECU 1. When the hydraulic control valves 41 and 42 are closed, the cylinders (# 1 to # 1) included in the first bank are closed. The intake and exhaust valves of # 3) are driven to open and close as usual, and all cylinder operation is performed. When the hydraulic control valves 41 and 42 are opened by a control signal from the ECU 1, hydraulic oil pressurized by the oil pump 43 is supplied to the cylinder deactivation mechanism 23. The intake valve and the exhaust valve of each cylinder (# 1 to # 3) included in the first bank are maintained in the closed state by the action of the hydraulic pressure, and the cylinder deactivation operation is performed.

  FIG. 3 shows a principle for detecting a failure of cylinder deactivation control according to an embodiment of the present invention. The failure of cylinder deactivation control in this specification includes any that may interfere with the normal operation of the intended cylinder deactivation operation. For example, not only a failure in the cylinder deactivation mechanism 23 but also mechanical elements related to the cylinder deactivation mechanism 23 (for example, not only the hydraulic control valves 41 and 42 and the oil pump 43 shown in FIG. Including faulty wiring etc.). Further, it is possible to include an abnormality such as a program and data provided in the ECU 1 for operating the cylinder deactivation mechanism 23 to perform cylinder deactivation control.

  Assume that the vehicle starts to decelerate at time t1. The deceleration may be accompanied by a fuel cut operation for stopping the fuel supply to the internal combustion engine, for example. The deceleration of the vehicle can be detected by the vehicle speed sensor 19 described above. Alternatively, the deceleration of the vehicle may be detected from the opening of the throttle valve 4. For example, if the throttle valve 4 is fully closed, it can be determined that deceleration has started. When the vehicle starts to decelerate, the intake air amount QAIR starts to decrease as indicated by the solid line 51.

  At time t2, a control signal for starting the cylinder deactivation operation is output from the ECU 1 to the cylinder deactivation mechanism 23 as described with reference to FIG. The cylinder deactivation mechanism 23 attempts to start cylinder deactivation operation. When the cylinder deactivation operation operates normally, the intake air amount QAIR changes as indicated by the solid line 51. When all cylinder operation continues due to some failure in the cylinder deactivation operation, the intake air amount QAIR changes as indicated by the broken line 52. As is apparent from the figure, when normal cylinder deactivation operation is performed, the intake air amount QAIR is greatly reduced as compared to all cylinder operation. Therefore, it is possible to determine whether or not the cylinder deactivation operation has been started normally by examining the intake air amount QAIR.

  Immediately after the cylinder deactivation operation is started, the intake air amount QAIR in the cylinder deactivation operation decreases at a larger rate (change rate) than in the all-cylinder operation, as shown by the solid line at time t2 to t3. This large decrease rate of the intake air amount is due to the fact that the number of cylinders to be sucked is reduced at a stroke by the start of the cylinder deactivation operation.

  In an embodiment of the present invention, the intake air amount QAIR detected by the air flow meter 7 is calculated immediately after the control signal for starting the cylinder deactivation operation is output from the ECU 1, that is, at a given time from time t2 to time t3. Compare with the first threshold value NQAIR1. The first threshold value NQAIR1 is set according to the elapsed time from the start of the cylinder deactivation operation, as indicated by a line 53. If the detected intake air amount QAIR is equal to or greater than the first threshold value NQAIR1, it indicates that the cylinder deactivation has not started normally, and therefore it is determined that some failure has occurred in the cylinder deactivation control.

  When the cylinder deactivation operation is normally continued, the rate at which the intake air amount QAIR decreases is substantially constant as shown by the solid line 51 at times t3 to t4. The reduction in the intake air amount here is caused by the vehicle decelerating. As shown in the figure, when the decrease rate of the intake air amount 51 in the cylinder deactivation operation is stabilized, the deviation 55 from the intake air amount (indicated by the line 52) in the all cylinder operation is also stabilized.

  In one embodiment of the present invention, the intake air amount QAIR detected by the air flow meter 7 at the time when the rate of decrease of the intake air amount becomes stable, that is, at a given time from time t3 to time t4, is set to a second value. Compare with threshold NQAIR2. The second threshold value NQAIR2 is set according to the elapsed time from the start of the cylinder deactivation operation, as indicated by a line 54. If the detected intake air amount QAIR is equal to or greater than the second threshold value NQAIR2, it indicates that the cylinder deactivation operation is not operating normally, and therefore it is determined that some failure has occurred in the cylinder deactivation control.

  The first threshold value NQAIR1 is set to a value that will naturally exceed when all-cylinder operation is continued. The second threshold value NQAIR2 is set to a value that would be naturally lower if the cylinder deactivation operation is normally continued.

  When the vehicle decelerates, a large difference in the intake air amount appears between the all cylinder operation and the cylinder deactivation operation as shown in the figure. Therefore, the failure of the cylinder deactivation control can be detected with better accuracy by performing the failure determination when the vehicle decelerates.

  In addition, immediately after the control signal for starting the cylinder deactivation operation is output from the ECU 1, the failure determination is performed using the first threshold value to quickly determine whether the cylinder deactivation operation has started normally. Can be judged.

  Furthermore, when the failure rate is determined using the second threshold value when the rate of decrease of the intake air amount becomes stable, it can be determined whether the cylinder deactivation operation continues normally thereafter. Since the rate of decrease in the intake air amount is stable, the accuracy of failure determination can be increased.

  In one embodiment, the first threshold value NQAIR1 and the second threshold value NQAIR2 corresponding to the elapsed time since the control signal for starting the cylinder deactivation control is output to the cylinder deactivation mechanism 23 are stored in the memory 1c as a map. Is remembered. The map can be referred to based on the elapsed time, and the corresponding first threshold value NQAIR1 and second threshold value NQAIR2 can be obtained.

  The amount of intake air varies depending on the engine speed NE. Therefore, it is preferable that the lines 53 and 54 of the first threshold value NQAIR1 and the second threshold value NQAIR2 are set according to the detected engine speed.

  Preferably, the line 53 indicating the first threshold value NQAIR1 is above the line 56 passing through the middle of the intake air amount difference 55 between the all cylinder operation and the cylinder deactivation operation when the decrease rate is stable. Is set. The line 54 indicating the second threshold value NQAIR2 is set below the line 56 passing through the middle of the difference 55. By setting the two threshold lines in this way, the line 53 indicating the first threshold value NQAIR1 is set close to the line 52 indicating the intake air amount characteristic of all cylinder operation. Therefore, the state where the cylinder deactivation operation is not started can be detected earlier. In addition, since the line 54 indicating the second threshold value NQAIR2 is set near the line 51 indicating the intake air amount characteristic in the cylinder deactivation operation, it is more reliable that the cylinder deactivation control is not normally performed. Can be detected.

  In one embodiment of the present invention, when the fuel cut is performed, the first and second threshold values are corrected according to the target intake air amount. Even in the same deceleration state, the target intake air amount differs between when the fuel cut is performed and when the fuel cut is not performed, and thus the air amount actually sucked into the engine is different. If the threshold value is corrected according to the target intake air amount, it is possible to more reliably determine the failure of cylinder deactivation control even when the fuel cut is being performed.

  In another embodiment, the above threshold value is corrected according to the intake air temperature detected by the intake air temperature sensor 9 (FIG. 1). Depending on the intake air temperature, the amount of air actually taken into the engine may differ, but with such correction, the influence of the intake air temperature can be suppressed and a failure in cylinder deactivation control can be determined.

  FIG. 4 shows a flowchart for determining failure of cylinder deactivation control according to an embodiment of the present invention. The processing shown in this flowchart is repeatedly executed at predetermined time intervals.

  In step S11, it is determined whether the vehicle is decelerating. If the vehicle is not decelerating, this process ends. If the vehicle is decelerating, the process proceeds to step S12. In addition to whether the vehicle is decelerating, it may be determined whether a fuel cut is being performed. For example, by examining a flag that is set to a value of 1 when deceleration with fuel cut is started, it can be determined whether or not deceleration with fuel cut is being performed.

  In step S12, a cylinder deactivation operation flag that is set to 1 when the control signal for starting the cylinder deactivation operation is output to the cylinder deactivation mechanism 23 is checked. If the value of the cylinder deactivation operation flag is zero, this process ends. If the value of the cylinder deactivation operation flag is 1, the process proceeds to step S13.

  In step S13, the detection value QAIR of the air flow meter 7 is acquired. In step S14, the previous value QAIR1 of the intake air amount detected by the air flow meter 7 is stored as QAIR2, and the current value QAIR of the intake air amount is stored as QAIR1.

  In step S15, the first threshold value NQAIR1 and the second NQAIR2 are obtained by referring to a predetermined map based on the elapsed time from the output of the control signal for starting the cylinder deactivation operation and the engine speed. As described above, when the fuel cut is being performed, it is preferable to correct the first threshold value NQAIR1 and the second threshold value NQAIR2 according to the target intake air amount.

  In step S16, as described above with reference to FIG. 3, the current value QAIR1 of the intake air amount is compared with the first threshold value NQAIR1. If QAIR1 ≧ NQAIR1, it indicates that the cylinder deactivation operation has not started normally. In this case, in step S20, it is determined that some failure has occurred in the cylinder deactivation control. When it is determined that there is a failure, it is preferable to notify the driver by turning on a warning light (MIL), for example.

  If QAIR1 <NQAIR1, the process proceeds to step S17, and the absolute value QAIR3 of the difference between the previous value QAIR2 of the intake air amount and the current value QAIR1 is calculated. QAIR3 indicates the magnitude of the reduction rate of the intake air amount.

  In step S18, QAIR3 is compared with a predetermined threshold value DQAIR. If QAIR3 ≧ DQAIR, it indicates that the decrease rate is not stable, and thus this processing is terminated. Thereafter, when this process is started again, if QAIR3 <DQAIR in step S18, it indicates that the rate of decrease of the intake air amount is stable, and the process proceeds to step S19.

  In step S19, the current value QAIR1 of the intake air amount is compared with the second threshold value NQAIR2. As described with reference to FIG. 3, if QAIR1 ≧ NQAIR2, it indicates that the cylinder deactivation control is not normally performed. In this case, in step S20, it is determined that some failure has occurred in the cylinder deactivation control. If QAIR1 <NQAIR2, it is determined that cylinder deactivation control is normal (S21).

  In the above embodiment, an internal combustion engine having six cylinders has been described. However, the present invention can be applied to an internal combustion engine having a plurality of arbitrary numbers of cylinders. For example, the present invention can also be applied to a four-cylinder engine that performs cylinder deactivation operation for only one of the four cylinders. Further, the present invention can be applied not only to gasoline vehicles but also to hybrid vehicles driven by gasoline and electricity, for example.

  The present invention can also be applied to other internal combustion engines (for example, outboard motors).

1 schematically shows an internal combustion engine and a control device according to one embodiment of the present invention. FIG. The figure which shows the outline | summary of the cylinder deactivation mechanism according to one Example of this invention. The figure for demonstrating the method of determining the failure of cylinder deactivation control according to one Example of this invention. The flowchart which determines the failure of cylinder deactivation control according to one Example of this invention.

Explanation of symbols

1 ECU
2 Engine 7 Air flow meter 23 Cylinder deactivation mechanism

Claims (6)

In a control device for an internal combustion engine including a mechanism for performing cylinder deactivation control for deactivating a part of a plurality of cylinders,
An intake air amount detection means provided in an intake system of the internal combustion engine for detecting an intake air amount to the internal combustion engine;
Deceleration state detecting means for detecting a deceleration state of a vehicle on which the internal combustion engine is mounted;
Command output means for outputting a command for starting the cylinder deactivation control to the internal combustion engine when the deceleration state is detected;
Comparing means for comparing the detected intake air amount with a threshold value set based on the rotational speed of the internal combustion engine after a command for starting the cylinder deactivation control is output to the internal combustion engine When,
Failure determination means for determining that a failure has occurred in the cylinder deactivation control when the detected intake air amount is equal to or greater than the threshold;
An internal combustion engine control device comprising: Furthermore, it comprises a change rate determination means for determining whether or not the change rate of the detected intake air amount is stable,
When the change rate determination means determines that the change rate is in a stable state, the failure determination means fails in the cylinder deactivation control when the detected intake air amount is greater than or equal to the threshold value. The control apparatus for an internal combustion engine according to claim 1, wherein it is determined that occurrence has occurred.   The control apparatus for an internal combustion engine according to claim 1 or 2, wherein the threshold value is corrected in accordance with a target intake air amount in a state in which fuel supply to the internal combustion engine is stopped.   The control apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the threshold value is corrected according to the detected intake air temperature. The comparison means further includes:
Immediately after the command for starting the cylinder deactivation control is output to the internal combustion engine, the detected intake air amount and a first threshold value set based on the rotational speed of the internal combustion engine are set. First comparing means for comparing;
When the change rate of the detected intake air amount is stable, the detected intake air amount is compared with a second threshold value set based on the rotational speed of the internal combustion engine. A comparison means,
The failure determination means further includes
First failure determination means for determining that some failure has occurred in the cylinder deactivation control if the detected intake air amount is not less than the first threshold value in the comparison by the first comparison means;
Second failure determination means for determining that some failure has occurred in the cylinder deactivation control if the detected intake air amount is equal to or greater than the second threshold value in the comparison by the second comparison means; The control device according to claim 1, further comprising:   The control apparatus for an internal combustion engine according to claim 5, wherein the second threshold value is set smaller than the first threshold value.

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